CN111668151B - Electrostatic chuck and processing apparatus - Google Patents
Electrostatic chuck and processing apparatus Download PDFInfo
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- CN111668151B CN111668151B CN202010143616.XA CN202010143616A CN111668151B CN 111668151 B CN111668151 B CN 111668151B CN 202010143616 A CN202010143616 A CN 202010143616A CN 111668151 B CN111668151 B CN 111668151B
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- 238000010891 electric arc Methods 0.000 description 66
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- 239000000463 material Substances 0.000 description 23
- 239000000853 adhesive Substances 0.000 description 18
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 12
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- 238000005229 chemical vapour deposition Methods 0.000 description 5
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- 230000003746 surface roughness Effects 0.000 description 5
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 239000002826 coolant Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000001307 helium Substances 0.000 description 4
- 229910052734 helium Inorganic materials 0.000 description 4
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 4
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 3
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- 238000005240 physical vapour deposition Methods 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000002679 ablation Methods 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000013464 silicone adhesive Substances 0.000 description 2
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- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
- H01L21/6831—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using electrostatic chucks
- H01L21/6833—Details of electrostatic chucks
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32431—Constructional details of the reactor
- H01J37/3244—Gas supply means
- H01J37/32449—Gas control, e.g. control of the gas flow
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32431—Constructional details of the reactor
- H01J37/32715—Workpiece holder
- H01J37/32724—Temperature
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67011—Apparatus for manufacture or treatment
- H01L21/67017—Apparatus for fluid treatment
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
- H01L21/6831—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using electrostatic chucks
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/002—Cooling arrangements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67011—Apparatus for manufacture or treatment
- H01L21/67098—Apparatus for thermal treatment
- H01L21/67109—Apparatus for thermal treatment mainly by convection
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Plasma & Fusion (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)
Abstract
The electrostatic chuck of the present invention comprises: a ceramic dielectric substrate having a1 st main surface on which an object to be adsorbed is placed, a 2 nd main surface on the opposite side of the 1 st main surface, and a groove opening to the 1 st main surface; a base plate which supports the ceramic dielectric substrate and has a gas introduction path; and a1 st porous portion provided between the gas introduction passages, the ceramic dielectric substrate having a plurality of holes that communicate the grooves with the gas introduction passages, the 1 st porous portion penetrating the ceramic dielectric substrate in a1 st direction from the base plate toward the ceramic dielectric substrate, the 1 st porous portion having: a porous region having a plurality of pores; and a dense region which is denser than the porous region, wherein the porous region further has a dense portion, and at least 1 of the plurality of holes provided in the ceramic dielectric substrate is configured to overlap at least 1 of the dense portions when projected onto a plane perpendicular to the 1 st direction.
Description
Technical Field
The present invention relates to an electrostatic chuck and a processing apparatus.
Background
An electrostatic chuck made of ceramic is manufactured by sandwiching an electrode between ceramic dielectric substrates such as alumina and firing the sandwiched electrodes, and is a substrate in which electrostatic attraction power is applied to the built-in electrodes, and silicon wafers and the like are attracted by electrostatic force. In such an electrostatic chuck, an inert gas such as helium (He) is introduced between the front surface of the ceramic dielectric substrate and the back surface of the substrate, which is the object to be adsorbed, to control the temperature of the substrate, which is the object to be adsorbed.
For example, among apparatuses for processing a substrate such as a chemical vapor deposition (CVD (Chemical Vapor Deposition)) apparatus, a sputtering (sputtering) apparatus, an ion implantation apparatus, and an etching (etching) apparatus, there are apparatuses that cause a temperature rise of the substrate during the processing. In an electrostatic chuck used in such a device, an inert gas such as He is introduced between a ceramic dielectric substrate and a substrate as an object to be adsorbed, and the inert gas is brought into contact with the substrate to suppress a temperature rise of the substrate.
In an electrostatic chuck in which the substrate temperature is controlled by an inert gas such as He, holes (gas introduction passages) for introducing the inert gas such as He are provided in a ceramic dielectric substrate and a susceptor plate for supporting the ceramic dielectric substrate. In addition, a through hole communicating with a gas introduction path of the base plate is provided in the ceramic dielectric substrate. Thus, the inert gas introduced from the gas introduction path of the base plate is introduced to the back surface of the substrate through the through-hole of the ceramic dielectric substrate.
Here, when a substrate is processed in the apparatus, discharge (arc discharge) from plasma in the apparatus to the metal susceptor plate may occur. The gas introduction path of the susceptor and the through-hole of the ceramic dielectric substrate may easily form a discharge path. Then, there is a technology of providing a porous portion in a gas introduction path of a base plate and a through hole of a ceramic dielectric substrate to improve resistance to arc discharge (dielectric strength and the like). For example, patent document 1 discloses an electrostatic chuck in which a ceramic sintered porous body is provided in a gas introduction path, and the structure and film pores of the ceramic sintered porous body are used as gas flow paths, thereby improving the insulation properties in the gas introduction path. Patent document 2 discloses an electrostatic chuck in which a discharge preventing member for a process gas flow path, which is made of a ceramic porous body and prevents discharge, is provided in a gas diffusion gap. Patent document 3 discloses an electrostatic chuck in which a dielectric insert is provided as a porous dielectric such as alumina to reduce arcing. Patent document 4 discloses a technique in which a plurality of fine holes communicating with a gas supply hole are provided in an electrostatic chuck made of aluminum nitride or the like by a laser processing method.
In such an electrostatic chuck, further reduction of arc discharge is required.
Patent literature
Patent document 1: japanese patent application laid-open No. 2010-123712
Patent document 2: japanese patent laid-open No. 2003-338492
Patent document 3: japanese patent application laid-open No. 10-50813
Patent document 4: japanese patent application laid-open No. 2009-218592
Disclosure of Invention
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an electrostatic chuck and a processing apparatus capable of reducing arc discharge.
The 1 st invention is an electrostatic chuck, comprising: a ceramic dielectric substrate having a1 st main surface on which an object to be adsorbed is placed, a2 nd main surface on the opposite side of the 1 st main surface, and at least 1 groove opening to the 1 st main surface; a base plate which supports the ceramic dielectric substrate and has a gas introduction path; and a1 st porous portion provided between the groove and the gas introduction path, wherein the ceramic dielectric substrate has a plurality of holes that communicate the groove and the gas introduction path, and penetrates the ceramic dielectric substrate in a1 st direction from the base plate toward the ceramic dielectric substrate, and the 1 st porous portion has: at least 1 porous region having a plurality of pores; and at least 1 dense region denser than the porous region, wherein the porous region further has at least 1 dense portion, and at least 1 of the plurality of holes provided in the ceramic dielectric substrate is configured to overlap at least 1 of the dense portions when projected onto a plane perpendicular to the 1 st direction.
According to this electrostatic chuck, when an electric current flows in the porous portion, the electric current flows around the dense portion. Therefore, since the distance (conduction path) over which the current flows can be lengthened, electrons are difficult to accelerate, so that the occurrence of arc discharge can be suppressed.
In the invention 2, the 1 st porous portion is provided on the ceramic dielectric substrate in the invention 1.
According to the electrostatic chuck, the mechanical strength (rigidity) of the ceramic dielectric substrate can be improved.
The 3 rd aspect is the electrostatic chuck according to the 1 st or 2 nd aspect, further comprising a2 nd porous portion provided between the groove and the gas introduction path, wherein the 2 nd porous portion is provided on the base plate.
According to the electrostatic chuck, an effective reduction of arc discharge can be achieved.
In the invention 4, in the invention 1, the 1 st porous portion is provided on the base plate.
According to the electrostatic chuck, arcing in the susceptor plate can be suppressed.
The 5 th aspect of the present invention is the electrostatic chuck according to any one of the 1 st to 4 th aspects of the present invention, wherein the porous region includes: a plurality of loose portions having a plurality of holes; and a compact portion having a density higher than that of the loose portion, a dimension in a 2 nd direction substantially orthogonal to the 1 st direction being smaller than a dimension of the compact region in the 2 nd direction, the plurality of loose portions extending in the 1 st direction, respectively, the compact portion being located between each other of the plurality of loose portions, the loose portion having wall portions provided between each other of the plurality of holes, a minimum value of the dimension of the wall portions being smaller than a minimum value of the dimension of the compact portion in the 2 nd direction substantially orthogonal to the 1 st direction.
According to this electrostatic chuck, since the porous portion is provided with the loose portion and the tight portion extending in the 1 st direction, the mechanical strength (rigidity) of the porous portion can be improved while ensuring the resistance to arc discharge and the gas flow rate.
In the electrostatic chuck according to the invention 6, in the invention 5, the sizes of the plurality of holes provided in the plurality of loose portions in the direction 2 are smaller than the sizes of the tight portions.
According to the electrostatic chuck, the occurrence of arc discharge can be more effectively suppressed.
The 7 th aspect of the present invention is the electrostatic chuck according to the 5 th or 6 th aspect of the present invention, wherein the aspect ratio of the plurality of holes provided in the plurality of loose portions is 30 or more.
According to the electrostatic chuck, the resistance to arc discharge can be further improved.
An 8 th aspect of the present invention is the electrostatic chuck according to any one of the 5 th to 7 th aspects of the present invention, wherein the plurality of holes provided in the plurality of loose portions in the 2 nd direction have a size of 1 μm or more and 20 μm or less.
According to the electrostatic chuck, since holes extending in 1 direction and having a hole size of 1 to 20 μm can be arranged, high resistance to arc discharge can be achieved.
The 9 th aspect of the present invention is the electrostatic chuck according to any one of the 5 th to 8 th aspects of the present invention, wherein the plurality of holes include a1 st hole located in a center portion of the loose portion when viewed in the 1 st direction, and a number of holes adjacent to the 1 st hole and surrounding the 1 st hole is 6 among the plurality of holes.
According to this electrostatic chuck, a plurality of holes can be arranged with a high isotropy and a high density in a plan view. This can ensure resistance to arc discharge and a gas flow rate of the gas flowing, and can improve the rigidity of the 1 st porous portion.
The 10 th aspect of the present invention is the electrostatic chuck according to any one of the 1 st to 9 th aspects of the present invention, wherein a length of the dense portion in the 1 st direction is smaller than a length of the 1 st porous portion in the 1 st direction.
According to the electrostatic chuck, the occurrence of arc discharge can be suppressed and the gas flow can be smoothed.
The 11 th invention is the electrostatic chuck according to any one of the 1 st to 9 th inventions, wherein a length of the dense portion in the 1 st direction is substantially equal to a length of the 1 st porous portion in the 1 st direction.
According to this electrostatic chuck, the length of the dense portion in the 1 st direction is substantially equal to the length of the porous portion in the 1 st direction, so that the occurrence of arcing can be more effectively suppressed.
In the invention 12, in any one of inventions 1 to 11, at least a part of an edge of the opening on the ceramic dielectric substrate side of the gas introduction path is formed by a curve.
According to this electrostatic chuck, since at least a part of the edge of the opening of the gas introduction path is formed by a curve, electric field concentration can be suppressed, so that reduction of arc discharge can be achieved.
The 13 th aspect of the present invention is the electrostatic chuck according to any one of the 1 st to 12 th aspects of the present invention, wherein at least 1 of the plurality of holes provided in the ceramic dielectric substrate has: part 1, open to the trough; and a2 nd portion which is connected to the 1 st portion and opens to the 2 nd main surface, wherein the 1 st portion has a smaller size than the 2 nd portion in the 2 nd direction substantially orthogonal to the 1 st direction.
According to the electrostatic chuck, the occurrence of arc discharge can be more effectively suppressed.
The 14 th aspect of the present invention is the electrostatic chuck according to any one of the 1 st to 13 th aspects of the present invention, wherein when an angle formed by an edge of an opening of the hole on the groove side and a bottom surface of the groove is defined as α and an angle formed by an edge of an opening of the hole on the 2 nd main surface side and the 2 nd main surface is defined as β, at least 1 of the plurality of holes provided in the ceramic dielectric substrate satisfies α < β.
According to the electrostatic chuck, electric field concentration can be suppressed, so that reduction of arc discharge can be achieved.
The 15 th aspect of the present invention is the electrostatic chuck according to any one of the 1 st to 14 th aspects of the present invention, wherein at least 1 of the plurality of holes provided in the ceramic dielectric substrate is inclined to the 1 st direction.
According to the electrostatic chuck, since at least 1 of the plurality of holes is inclined to the 1 st direction, electrons are considered to be difficult to accelerate when a current flows inside the holes. Therefore, the occurrence of arc discharge can be effectively suppressed.
In the 15 th aspect, the angle inclined to the 1 st direction is 5 ° or more and 30 ° or less.
According to the electrostatic chuck, the occurrence of arc discharge can be suppressed without reducing the diameter of the hole.
The 17 th invention is an electrostatic chuck, comprising: a ceramic dielectric substrate having a 1 st main surface on which an object to be adsorbed is placed, a2 nd main surface on the opposite side of the 1 st main surface, and at least 1 groove opening to the 1 st main surface; a base plate which supports the ceramic dielectric substrate and has a gas introduction path; and a 1 st porous portion provided between the groove and the gas introduction path, wherein the ceramic dielectric substrate has a plurality of holes communicating the groove and the gas introduction path, the ceramic dielectric substrate is penetrated in a 1 st direction from the base plate toward the ceramic dielectric substrate, and at least 1 of the plurality of holes is inclined to the 1 st direction.
If at least 1 of the plurality of holes is inclined to the 1 st direction, electrons are difficult to accelerate when a current flows inside the holes. Therefore, the occurrence of arc discharge can be effectively suppressed.
The 18 th aspect of the present invention is a processing apparatus comprising: any one of the electrostatic chucks described above; and a supply unit configured to supply a gas to a gas introduction path provided in the electrostatic chuck.
According to this processing apparatus, reduction of arc discharge can be achieved.
According to an aspect of the present invention, there is provided an electrostatic chuck and a processing apparatus capable of reducing arc discharge.
Drawings
Fig. 1 is a schematic cross-sectional view illustrating an electrostatic chuck according to the present embodiment.
Fig. 2 (a) to (d) are schematic views illustrating electrostatic chucks according to the embodiment.
Fig. 3 (a) and (b) are schematic views illustrating porous portions of an electrostatic chuck according to an embodiment.
Fig. 4 is a schematic plan view illustrating a porous portion of an electrostatic chuck according to an embodiment.
Fig. 5 is a schematic plan view illustrating a porous portion of an electrostatic chuck according to an embodiment.
Fig. 6 (a) and (b) are schematic plan views illustrating porous portions of an electrostatic chuck according to an embodiment.
Fig. 7 (a) and (b) are schematic views illustrating the 1 st porous portion 90 according to another embodiment.
Fig. 8 is a schematic cross-sectional view illustrating an electrostatic chuck according to an embodiment.
Fig. 9 (a) and (b) are schematic cross-sectional views illustrating an electrostatic chuck according to an exemplary embodiment.
Fig. 10 is a schematic cross-sectional view illustrating a porous portion of an electrostatic chuck according to an embodiment.
Fig. 11 is a schematic cross-sectional view illustrating a porous portion according to another embodiment.
Fig. 12 (a) and (b) are schematic cross-sectional views illustrating porous portions according to other embodiments.
Fig. 13 (a) to (d) are schematic cross-sectional views illustrating porous portions according to other embodiments.
Fig. 14 (a) to (c) are schematic cross-sectional views illustrating porous portions according to other embodiments.
Fig. 15 (a) and (b) are schematic cross-sectional views illustrating porous portions according to other embodiments.
Fig. 16 is a schematic cross-sectional view illustrating an electrostatic chuck according to another embodiment.
Fig. 17 (a) and (b) are enlarged views of the region C shown in fig. 16.
Fig. 18 is a schematic cross-sectional view illustrating a plurality of holes according to another embodiment.
Fig. 19 (a) and (b) are schematic cross-sectional views illustrating the shape of the opening portion of the hole.
Fig. 20 is a schematic cross-sectional view illustrating an electrostatic chuck according to another embodiment.
Fig. 21 is a schematic cross-sectional view illustrating an electrostatic chuck according to another embodiment.
Fig. 22 is a schematic cross-sectional view illustrating an electrostatic chuck according to another embodiment.
Fig. 23 is an enlarged view of the area E shown in fig. 22.
Fig. 24 is an enlarged view showing another embodiment of the region E shown in fig. 22.
Fig. 25 is a schematic diagram illustrating a processing device according to the present embodiment.
Symbol description
11-A ceramic dielectric substrate; 11 a-1 st main face; 11 b-main 2; 11 c-a ceramic dielectric substrate; 12-electrode; 14-groove; 14 a-bottom surface; 15-through holes; 15 a-hole portion; 15 b-hole portion; 15 c-hole portion; 15c 1-side; 15 d-hole portion; 16-holes; 16 h-hole; 16 i-edges; 16 j-edge; 50-base plate; 53-a gas introduction path; 53 b-edge; 60-joint; 70-a porous portion; 70 a-a porous portion; 71-a porous region; 72-dense region; 90-a porous portion; 90 a-a porous portion; 90 b-a porous portion; 92 a-densification; 92 b-dense part; 96-well; 110-an electrostatic chuck; 110 a-an electrostatic chuck; 200-a processing device; 210-a power supply; 230-a supply section; w-object.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.
In each drawing, the direction from the base plate 50 toward the ceramic dielectric substrate 11 is referred to as the Z direction (corresponding to one example of the 1 st direction), 1 of the directions substantially orthogonal to the Z direction is referred to as the Y direction (corresponding to one example of the 2 nd direction), and the directions substantially orthogonal to the Z direction and the Y direction are referred to as the X direction (corresponding to one example of the 2 nd direction).
Electrostatic chuck
Fig. 1 is a schematic cross-sectional view illustrating an electrostatic chuck according to the present embodiment.
As shown in fig. 1, the electrostatic chuck 110 according to the present embodiment includes a ceramic dielectric substrate 11, a base plate 50, and a porous portion 90. In this example, the electrostatic chuck 110 further includes a porous portion 70.
The ceramic dielectric substrate 11 is a flat plate-shaped base material formed of, for example, sintered ceramic. For example, the ceramic dielectric substrate 11 contains alumina (Al 2O3). For example, the ceramic dielectric substrate 11 is made of high purity alumina. The concentration of alumina in the ceramic dielectric substrate 11 is, for example, 99 atomic% or more and 100 atomic% or less. By using alumina of high purity, the plasma resistance of the ceramic dielectric substrate 11 can be improved. The ceramic dielectric substrate 11 has: a 1 st main surface 11a on which an object W (adsorption object) is placed; and a 2 nd main surface 11b located on the opposite side of the 1 st main surface 11 a. The object W is a semiconductor substrate such as a silicon wafer.
An electrode 12 is provided in the ceramic dielectric substrate 11. The electrode 12 is provided between the 1 st main surface 11a and the 2 nd main surface 11b of the ceramic dielectric substrate 11. The electrode 12 is formed so as to be inserted into the ceramic dielectric substrate 11. The power supply 210 is electrically connected to the electrode 12 via the connection portion 20 and the wiring 211. By applying a voltage for holding the object W to the electrode 12 by the power supply 210, electric charges are generated on the 1 st main surface 11a side of the electrode 12, and the object W can be held by electrostatic force.
The electrode 12 is thin in shape along the 1 st main surface 11a and the 2 nd main surface 11b of the ceramic dielectric substrate 11. The electrode 12 is an adsorption electrode for adsorbing and holding the object W. The electrode 12 may be either monopolar or bipolar. The electrode 12 illustrated in fig. 1 is bipolar, and 2-pole electrodes 12 are provided on the same surface.
The electrode 12 is provided with a connection portion 20 extending toward the 2 nd main surface 11b of the ceramic dielectric substrate 11. The connection portion 20 is, for example, a Via (Via) (solid type) or a Via (Via Hole) (hollow type) that is connected to the electrode 12. The connection portion 20 may be a metal terminal connected by a suitable method such as soldering.
The base plate 50 is a member for supporting the ceramic dielectric substrate 11. The ceramic dielectric substrate 11 is fixed to the base plate 50 via the joint 60 illustrated in fig. 2 (a). For example, a portion where the silicone adhesive is cured can be used as the joint 60.
The base plate 50 is made of metal, for example. The base plate 50 is divided into an upper portion 50a and a lower portion 50b made of aluminum, for example, and a communication passage 55 is provided between the upper portion 50a and the lower portion 50 b. One end of the communication path 55 is connected to the input path 51, and the other end of the communication path 55 is connected to the output path 52. The base plate 50 may further have a plating portion (not shown) at the end portion on the 2 nd main surface 11b side. The plating section is formed by, for example, plating. The plating section may also constitute an end surface (upper surface 50U) of the base plate 50 on the 2 nd main surface 11b side. The plating section is provided as needed and may be omitted.
The base plate 50 also functions as a temperature regulator for the electrostatic chuck 110. For example, when the electrostatic chuck 110 is cooled, the cooling medium flows in from the input path 51 and flows out from the output path 52 through the communication path 55. Thereby, the ceramic dielectric substrate 11 mounted thereon can be cooled by absorbing heat of the base plate 50 by the cooling medium. On the other hand, when the electrostatic chuck 110 is insulated, a heat insulating medium may be placed in the communication path 55. The heat generator may be placed inside the ceramic dielectric substrate 11 and the base plate 50. By adjusting the temperatures of the base plate 50 and the ceramic dielectric substrate 11, the temperature of the object W held by the electrostatic chuck 110 can be adjusted.
Further, on the 1 st main surface 11a side of the ceramic dielectric substrate 11, dots 13 are provided as necessary, and grooves 14 are provided between the dots 13. That is, the 1 st main surface 11a is a concave-convex surface, and has a concave portion and a convex portion. The convex portion of the 1 st main surface 11a corresponds to the point 13, and the concave portion of the 1 st main surface 11a corresponds to the groove 14. The grooves 14 may extend continuously in the XY plane, for example. This allows the gas such as He to be distributed over the entire 1 st main surface 11 a. A space is formed between the back surface of the object W placed on the electrostatic chuck 110 and the 1 st main surface 11a including the groove 14.
The ceramic dielectric substrate 11 has a through hole 15 connected to the groove 14. The through holes 15 are provided in a span from the 2 nd main surface 11b to the 1 st main surface 11 a. That is, the through-hole 15 extends in the Z direction from the 2 nd main surface 11b to the 1 st main surface 11a, and penetrates the ceramic dielectric substrate 11. The through hole 15 includes, for example, a hole 15a, a hole 15b, a hole 15c, and a hole 15d (described in detail later).
By appropriately selecting the height of the point 13, the depth of the groove 14, the area ratio of the point 13 to the groove 14, the shape, and the like, the temperature of the object W and the particles adhering to the object W can be controlled to a preferable state.
The gas introduction path 53 is provided in the base plate 50. The gas introduction path 53 is provided so as to penetrate the base plate 50, for example. The gas introduction path 53 may be provided on the ceramic dielectric substrate 11 side without penetrating the base plate 50 and branching off from the other gas introduction path 53. The gas introduction passages 53 may be provided at a plurality of positions on the base plate 50.
The gas introduction passage 53 communicates with the through hole 15. That is, the gas (helium (He) or the like) flowing into the gas introduction path 53 flows into the through-hole 15 after passing through the gas introduction path 53.
The gas flowing into the through-hole 15 passes through the through-hole 15 and then flows into the space provided between the object W and the 1 st main surface 11a of the containing groove 14. Thereby, the object W can be directly cooled by the gas.
The porous portion 90 is provided between the base plate 50 and the 1 st main surface 11a of the ceramic dielectric substrate 11, for example, in the Z direction. The porous portion 90 may be provided at a position facing the gas introduction path 53, for example. For example, the porous portion 90 is provided in the through hole 15 of the ceramic dielectric substrate 11. For example, the porous portion 90 is inserted into the through hole 15.
Fig. 2 (a) and (b) are schematic views illustrating an electrostatic chuck according to an embodiment. Fig. 2 (a) illustrates the periphery of the porous portion 90 and the porous portion 70. Fig. 2 (a) corresponds to an enlarged view of the region a shown in fig. 1. Fig. 2 (b) is a plan view illustrating the porous portion 90.
Fig. 2 (c) and (d) are schematic cross-sectional views illustrating the hole 15c and the hole 15d according to another embodiment.
In order to avoid complication, the point 13 (for example, see fig. 1) is omitted in fig. 2 (a), (c), and (d).
In this example, the through hole 15 has a hole portion 15a and a hole portion 15b (1 st hole portion). One end of the hole 15a is located on the 2 nd main surface 11b of the ceramic dielectric substrate 11.
The ceramic dielectric substrate 11 may have a hole portion 15b located between the 1 st main surface 11a and the porous portion 90 in the Z direction. The hole 15b communicates with the hole 15a and extends to the 1 st main surface 11a of the ceramic dielectric substrate 11. That is, one end of the hole 15b is located on the 1 st main surface 11a (the bottom surface 14a of the groove 14). The hole 15b is located between the 1 st main surface 11a of the ceramic dielectric substrate 11 and the 1 st porous portion 90. The hole 15b is a connection hole connecting the porous portion 90 and the groove 14. The diameter (length in the X direction) of the hole portion 15b is smaller than the diameter (length in the X direction) of the hole portion 15 a. By providing the hole 15b having a small diameter, the degree of freedom in designing the space (for example, the 1 st main surface 11a including the groove 14) formed between the ceramic dielectric substrate 11 and the object W can be improved. For example, as shown in fig. 2 (a), the width (length in the X direction) of the groove 14 can be made smaller than the width (length in the X direction) of the porous portion 90. This makes it possible to suppress discharge in a space provided between the ceramic dielectric substrate 11 and the object W, for example.
The diameter of the hole 15b is, for example, 0.05 millimeters (mm) or more and 0.5mm or less. The diameter of the hole 15a is, for example, 1mm to 5 mm. The hole 15b may be indirectly connected to the hole 15a. That is, a hole 15c (2 nd hole) connecting the hole 15a and the hole 15b may be provided. As illustrated in fig. 2 (a), the hole 15c may be provided in the ceramic dielectric substrate 11. As illustrated in fig. 2 (c), the hole 15c may be provided in the porous portion 90. As illustrated in fig. 2 (d), the holes 15c may be provided in the ceramic dielectric substrate 11 and the porous portion 90. That is, at least one of the ceramic dielectric substrate 11 and the porous portion 90 may have a hole portion 15c located between the hole portion 15b and the porous portion 90. In this case, if the hole 15c is provided in the ceramic dielectric substrate 11, strength around the hole 15c can be improved, and occurrence of inclination or the like around the hole 15c can be suppressed. Therefore, the occurrence of arc discharge can be more effectively suppressed. If the hole 15c is provided in the porous portion 90, the hole 15c and the porous portion 90 can be easily aligned. Therefore, it is easier to simultaneously reduce arc discharge and smooth gas flow. The hole 15a, the hole 15b, and the hole 15c are, for example, cylindrical and extend in the Z direction.
At this time, the size of the hole 15c can be made smaller than the size of the porous portion 90 and larger than the size of the hole 15b in the X direction or the Y direction. According to the electrostatic chuck 110 of the present embodiment, the porous portion 90 provided at a position facing the gas introduction path 53 can ensure the flow rate of the gas flowing through the hole portion 15b and can improve the resistance to arc discharge. Since the dimension of the hole 15c in the X direction or the Y direction is larger than that of the hole 15b, most of the gas introduced into the large-sized porous portion 90 can be introduced into the small-sized hole 15b through the hole 15 c. That is, the arc discharge can be reduced and the gas flow can be smoothed.
As described above, the ceramic dielectric substrate 11 has at least 1 groove 14 which opens to the 1 st main surface 11a and communicates with the through hole 15. In addition, the dimension of the hole 15c in the Z direction can be made smaller than the dimension of the groove 14 in the Z direction. This can shorten the time for the gas to pass through the hole 15 c. That is, the occurrence of arc discharge can be more effectively suppressed while smoothing the gas flow. In addition, the size of the hole 15c can be made larger than the size of the groove 14 in the X direction or the Y direction. In this way, the gas easily flows into the groove 14. Therefore, the object W can be cooled effectively by the gas.
In addition, the arithmetic average surface roughness Ra of the surface 15c1 (top surface) on the 1 st main surface 11a side of the hole 15c is preferably smaller than the arithmetic average surface roughness Ra of the bottom surface 14a (surface on the 2 nd main surface 11b side) of the groove 14. In this way, since the large uneven portion does not exist on the surface 15c1 of the hole 15c, the occurrence of arc discharge can be effectively suppressed.
In addition, the arithmetic average surface roughness Ra of the surface 14a of the groove 14 on the 2 nd main surface 11b side is preferably made smaller than the arithmetic average surface roughness Ra of the 2 nd main surface 11 b. In this way, since the large uneven portion does not exist on the surface 14a of the groove 14, the occurrence of arc discharge can be effectively suppressed.
In addition, a hole 15d (3 rd hole) provided between the hole 15b and the hole 15c may be provided. The hole 15d can be larger in size than the hole 15b and smaller than the hole 15c in the X direction or the Y direction. If the hole 15d is provided, the gas flow can be smoothed.
As described above, the joint portion 60 can be provided between the ceramic dielectric substrate 11 and the base plate 50. In the Z direction, the size of the hole portion 15c can be made smaller than the size of the joint portion 60. In this way, the bonding strength between the ceramic dielectric substrate 11 and the base plate 50 can be improved. In addition, since the size of the hole portion 15c in the Z direction is made smaller than the size of the joint portion 60, it is possible to more effectively suppress the occurrence of arc discharge while achieving the smoothness of the gas flow.
In this example, the porous portion 90 is provided in the hole portion 15a. Therefore, the upper surface 90U of the porous portion 90 is not exposed to the 1 st main surface 11 a. That is, the upper surface 90U of the porous portion 90 is located between the 1 st main surface 11a and the 2 nd main surface 11 b. On the other hand, the lower surface 90L of the porous portion 90 is exposed to the 2 nd main surface 11 b.
The porous portion 90 will be described next. The porous portion 90 has a plurality of loose portions 94 and a plurality of tight portions 95, which will be described later. Although fig. 2 illustrates the case where the porous portion 90 is provided on the ceramic substrate 11, the porous portion 90 may be provided on the base plate 50 (for example, fig. 12 (b)) as described later.
The porous portion 90 has: porous region 91 (one example of the 1 st porous region and the 2 nd porous region) has a plurality of holes 96; and a dense region 93 (an example of the 1 st dense region and the 2 nd dense region) which is denser than the porous region 91. Porous region 91 is configured to be gas-permeable. The gas circulates inside each of the plurality of holes 96. Dense region 93 is a region with fewer holes 96 than porous region 91 or a region with substantially no holes 96. The porosity (percent:%) of the dense region 93 is lower than the porosity (%) of the porous region 91. The density of the dense region 93 (g/cc: g/cm 3) is higher than the density of the porous region 91 (g/cm 3). Since the dense region 93 is denser than the porous region 91, for example, the rigidity (mechanical strength) of the dense region 93 is higher than that of the porous region 91.
The porosity of the dense region 93 is, for example, the volume ratio of the space (the hole 96) included in the dense region 93 to the entire volume of the dense region 93. The porosity of the porous region 91 is, for example, the volume ratio of the space (the holes 96) included in the porous region 91 to the entire volume of the porous region 91. For example, the porosity of the porous region 91 is 5% or more and 40% or less, preferably 10% or more and 30% or less, and the porosity of the dense region 93 is 0% or more and 5% or less.
The porous portion 90 has a columnar shape (e.g., a cylindrical shape). The porous region 91 has a columnar shape (e.g., a cylindrical shape). The dense region 93 contacts the porous region 91 or is continuous with the porous region 91. As shown in fig. 2 (b), when projected to a plane (XY plane) perpendicular to the Z direction, the dense region 93 encloses the outer periphery of the porous region 91. The dense region 93 has a cylindrical shape (for example, a cylindrical shape) surrounding the side surface 91s of the porous region 91. In other words, the porous region 91 is provided to penetrate the dense region 93 in the Z direction. The gas flowing from the gas introduction path 53 into the through hole 15 is supplied to the groove 14 through a plurality of holes provided in the porous region 91.
By providing the porous portion 90 having such a porous region 91, the resistance to arc discharge can be improved while ensuring the gas flow rate flowing through the through hole 15. Further, since the porous portion 90 has the dense region 93, the rigidity (mechanical strength) of the porous portion 90 can be improved.
In the case where the porous portion 90 is provided on the ceramic dielectric substrate 11, the porous portion may be integrated with the ceramic dielectric substrate 11, for example. The state in which 2 members are integrated means that 2 members are in a chemically bonded state. Between the 2 members, no material (e.g., adhesive) is provided for securing one member to the other. That is, in this example, other members such as an adhesive are not provided between the porous portion 90 and the ceramic dielectric substrate 11, and the porous portion 90 and the ceramic dielectric substrate 11 are integrated.
By integrating with the ceramic dielectric substrate 11 in this way, the strength of the electrostatic chuck 110 can be further improved when the porous portion 90 is fixed to the ceramic dielectric substrate 11 than when the porous portion 90 is fixed to the ceramic dielectric substrate 11 by an adhesive or the like. For example, the electrostatic chuck is not degraded by corrosion, ablation, etc. of the adhesive.
When the porous portion 90 and the ceramic dielectric substrate 11 are integrated, the side surface of the outer periphery of the porous portion 90 may receive a force from the ceramic dielectric substrate 11. On the other hand, when a plurality of holes are provided in the porous portion 90 to ensure the flow rate of the gas, the mechanical strength of the porous portion 90 is reduced. Therefore, when the porous portion 90 is integrated with the ceramic dielectric substrate 11, the porous portion 90 may be broken by a force applied from the ceramic dielectric substrate 11 to the porous portion 90.
In contrast, since the porous portion 90 has the dense region 93, the rigidity (mechanical strength) of the porous portion 90 can be improved, and the porous portion 90 can be integrated with the ceramic dielectric substrate 11.
In the embodiment, the porous portion 90 may not necessarily be integrated with the ceramic dielectric substrate 11. For example, as shown in fig. 11, the porous portion 90 may be mounted on the ceramic dielectric substrate with an adhesive.
The dense region 93 is located between the inner wall 15w of the ceramic dielectric substrate 11 where the through-hole 15 is formed and the porous region 91. That is, the porous region 91 is provided inside the porous portion 90, and the dense region 93 is provided outside. By providing the dense region 93 outside the porous portion 90, the rigidity against the force applied from the ceramic dielectric substrate 11 to the porous portion 90 can be improved. This makes it possible to easily integrate the porous portion 90 with the ceramic dielectric substrate 11. In addition, for example, when the adhesive member 61 is provided between the porous portion 90 and the ceramic dielectric substrate 11 (see fig. 11), the dense region 93 can suppress the gas passing through the inside of the porous portion 90 from contacting the adhesive member 61. This can suppress the occurrence of aging of the adhesive member 61. Further, by providing the porous region 91 inside the porous portion 90, the through-holes 15 of the ceramic dielectric substrate 11 are prevented from being blocked by the dense region 93, and the flow rate of the gas can be ensured.
The thickness of the dense portion 93 (length L0 between the side surface 91s of the porous region 91 and the side surface 93s of the dense region 93) is, for example, 100 μm or more and 1000 μm or less.
As a material of the porous portion 90, a ceramic having insulating properties is used. The porous portion 90 (each of the porous region 91 and the dense region 93) contains at least one of alumina (Al 2O3), titania (TiO 2), and yttria (Y 2O3). This can provide the porous portion 90 with high dielectric strength and high rigidity.
For example, the porous portion 90 contains any one of alumina, titania, and yttria as a main component.
In this case, the purity of alumina of the ceramic dielectric substrate 11 can be made higher than that of alumina of the porous portion 90. In this way, the performance such as plasma resistance of the electrostatic chuck 110 can be ensured, and the mechanical strength of the porous portion 90 can be ensured. As an example, by incorporating a small amount of an additive in the porous portion 90, sintering of the porous portion 90 is promoted, and control of pores and mechanical strength can be ensured.
In the present specification, the purity of ceramics such as alumina of the ceramic dielectric substrate 11 can be measured by fluorescent X-ray analysis, ICP-AES method (Inductively Cou PLED PLASMA-Atomic Emission Spectrometry: inductively coupled plasma atomic emission spectrometry), or the like.
For example, the porous region 91 is of the same material as the dense region 93. The material of porous region 91 may also be different from the material of dense region 93. The composition of the material of porous region 91 may also be different from the composition of the material of dense region 93.
Fig. 3 (a) and (b) are schematic views illustrating the porous portion 90 of the electrostatic chuck according to the embodiment.
Fig. 3 (a) is a plan view of the porous portion 90 as viewed along the Z direction, and fig. 3 (b) is a cross-sectional view of the porous portion 90 in the ZY plane.
As shown in fig. 3 (a) and 3 (b), the porous region 91 of the porous portion 90 includes a plurality of porous portions 94 (1 st porous portion, one example of 2 nd porous portion) and a compact portion 95 (1 st compact portion, one example of 2 nd compact portion). There may also be a plurality of tight portions 95. The plurality of loose portions 94 each have a plurality of holes 96. The dense portion 95 is denser than the loose portion 94. That is, the compact portion 95 is a portion less porous than the loose portion 94 or a portion substantially having no pores. The size of the compact portion 95 in the X direction or the Y direction is smaller than the size of the compact region 93 in the X direction or the Y direction. The porosity of the dense portion 95 is lower than that of the loose portion 94. Thus, the density of the dense portion 95 is higher than that of the loose portion 94. The porosity of the dense portion 95 may also be the same as the porosity of the dense region 93. Since the compact portion 95 is denser than the loose portion 94, the rigidity of the compact portion 95 is higher than that of the loose portion 94.
The porosity of 1 loose portion 94 is, for example, the volume ratio of the space (hole 96) included in the loose portion 94 to the entire volume of the loose portion 94. The porosity of the compact portion 95 is, for example, the volume ratio of the space (the hole 96) included in the compact portion 95 to the entire volume of the compact portion 95. For example, the porosity of the loose portion 94 is 20% or more and 60% or less, preferably 30% or more and 50% or less, and the porosity of the compact portion 95 is 0% or more and 5% or less.
The plurality of loose portions 94 extend in the Z direction, respectively. For example, the plurality of loose portions 94 are each columnar (cylindrical or polygonal columnar) and are provided so as to penetrate the porous region 91 in the Z direction. The tight portion 95 is located between each other of the plurality of loose portions 94. The compact portion 95 is in the form of a wall separating the mutually adjoining loose portions 94. As shown in fig. 3 (a), the compact portion 95 is provided so as to enclose the respective outer circumferences of the plurality of loose portions 94 when projected to a plane (XY plane) perpendicular to the Z direction. The dense section 95 is continuous with the dense region 93 at the outer periphery of the porous region 91.
The number of the loose portions 94 provided in the porous region 91 is, for example, 50 or more and 1000 or less. As shown in fig. 3 (a), when projected onto a plane (XY plane) perpendicular to the Z direction, the plurality of loose portions 94 are substantially the same size as each other. For example, when projected to a plane (XY plane) perpendicular to the Z direction, the plurality of loose portions 94 are isotropically equally dispersed within the porous region 91. For example, the distance between adjacent loose portions 94 (i.e., the thickness of the tight portion 95) is substantially constant.
For example, when projected onto a plane (XY plane) perpendicular to the Z direction, a distance L11 between the side surface 93s of the dense region 93 and the loose portion 94 closest to the side surface 93s among the plurality of loose portions 94 is 100 μm or more and 1000 μm or less.
By providing the porous region 91 with the plurality of loose portions 94 and the dense portions 95 denser than the loose portions 94 in this manner, the rigidity of the porous portion 90 can be improved while ensuring the resistance to arc discharge and the gas flow rate flowing through the through-holes 15, as compared with the case where the plurality of holes are randomly dispersed in 3 dimensions in the porous region.
For example, if the porosity of the porous region 91 becomes large, the flow rate of the gas increases, and the resistance to arc discharge and rigidity decrease. In contrast, even when the porosity is increased by providing the dense portion 95 having the X-direction or Y-direction smaller than the X-direction or Y-direction of the dense region 93 in the porous region 91, the reduction in resistance to arc discharge and rigidity can be suppressed.
For example, when projected to a plane (XY plane) perpendicular to the Z direction, a smallest circle, ellipse, or polygon including all of the plurality of loose portions 94 is envisaged. The inner side of the circle, ellipse, or polygon can be regarded as the porous region 91 and the outer side of the circle, ellipse, or polygon can be regarded as the dense region 93.
As described above, the porous portion 90 may include: a plurality of loose portions 94 having a plurality of holes 96 including a1 st hole 96, a 2 nd hole 96; and a compact portion 95 having a density higher than that of the loose portion 94. The plurality of loose portions 94 extend in the Z direction, respectively. The tight portion 95 is located between each other of the plurality of loose portions 94. The loose portion 94 has wall portions 97 (examples of the 1 st wall portion and the 2 nd wall portion) provided between each other (between the 1 st hole 96 and the 2 nd hole 96) of the plurality of holes 96. The minimum value of the dimension of the wall portion 97 can be made smaller than the minimum value of the dimension of the compact portion 95 in the X-direction or the Y-direction. In this way, since the porous portion 90 is provided with the loose portion 94 and the tight portion 95 extending in the Z direction, the mechanical strength (rigidity) of the porous portion 90 can be improved while ensuring the resistance to arc discharge and the gas flow rate.
As illustrated in fig. 5 described later, the size of the plurality of holes 96 provided in the plurality of loose portions 94 can be made smaller than the size of the compact portion 95 in the X-direction or the Y-direction. In this way, since the size of the plurality of holes 96 can be sufficiently reduced, the resistance to arc discharge can be further improved.
In addition, the aspect ratio (aspect ratio) of the plurality of holes 96 provided in the plurality of loose portions 94 can be set to 30 or more and 10000 or less. In this way, the resistance to arc discharge can be further improved. More preferably, the aspect ratio (aspect ratio) of the plurality of holes 96 has a lower limit of 100 or more and an upper limit of 1600 or less.
In addition, the size of the plurality of holes 96 provided in the plurality of loose portions 94 may be 1 μm or more and 20 μm or less in the X-direction or the Y-direction. In this way, since the holes 96 extending in 1 direction with the size of the holes 96 being 1 to 20 μm can be aligned, a high resistance to arc discharge can be achieved.
As will be described later with reference to fig. 6 (a) and (b), when projected on a plane (X Y plane) perpendicular to the Z direction, the hole 96a is located at the center of the loose portion 94, and the number of holes 96b to 96g adjacent to the hole 96a and surrounding the hole 96a may be 6 among the plurality of holes 96. In this way, the plurality of holes can be arranged with high isotropy and high density in a plan view. This can ensure resistance to arc discharge and a flow rate of the flowing gas, and can improve the rigidity of the porous portion 90.
Fig. 4 is a schematic plan view illustrating the porous portion 90 of the electrostatic chuck according to the embodiment.
Fig. 4 shows a part of the porous portion 90 as seen along the Z direction, which corresponds to an enlarged view of fig. 3 (a).
The plurality of loose portions 94 are each substantially hexagonal (substantially regular hexagonal) when projected to a plane (XY plane) perpendicular to the Z direction. When projected to a plane (XY plane) perpendicular to the Z direction, the plurality of loose portions 94 have: a loose portion 94a located at the center of the porous region 91; and 6 loose portions 94 (loose portions 94b to 94 g) surrounding the loose portion 94a.
The loose portions 94 b-94 g are adjacent to the loose portion 94a. The loose portions 94b to 94g are disposed closest to the loose portion 94a among the plurality of loose portions 94.
The loose portion 94b and the loose portion 94c are juxtaposed with the loose portion 94a in the X direction. That is, the loose portion 94a is located between the loose portion 94b and the loose portion 94 c.
The length L1 of the loose portion 94a in the X direction (the diameter of the loose portion 94 a) is longer than the length L2 between the loose portion 94a and the loose portion 94b in the X direction, and longer than the length L3 between the loose portion 94a and the loose portion 94c in the X direction.
The length L2 and the length L3 correspond to the thickness of the compact portion 95, respectively. That is, the length L2 is the length of the compact portion 95 between the loose portion 94a and the loose portion 94b in the X direction. The length L3 is the length of the compact portion 95 between the loose portion 94a and the loose portion 94c in the X direction. The length L2 can be made substantially the same as the length L3. For example, the length L2 may be set to be 0.5 to 2.0 times the length L3.
In addition, the length L1 can be made substantially the same as the length L4 of the loose portion 94b in the X direction (the diameter of the loose portion 94 b). The length L1 can be made substantially the same as the length L5 of the loose portion 94c in the X direction (the diameter of the loose portion 95 c). For example, the length L4 and the length L5 may be set to be 0.5 times or more and 2.0 times or less, respectively, of the length L1.
As such, the loose portion 94a adjoins and is enclosed by 6 loose portions 94 among the plurality of loose portions 94. That is, when projected onto a plane (XY plane) perpendicular to the Z direction, the number of loose portions 94 adjacent to 1 loose portion 94 is 6 at the center portion of the porous region 91. Thus, the plurality of loose portions 94 can be arranged with a high isotropy and a high density in a plan view. This can ensure resistance to arc discharge and a gas flow rate flowing through the through-hole 15, and can improve the rigidity of the porous portion 90. Further, variations in the resistance to arc discharge, variations in the flow rate of the gas flowing through the through-hole 15, and variations in the rigidity of the porous portion 90 can be suppressed.
The diameter (length L1, L4, L5, etc.) of the loose portion 94 is, for example, 50 μm or more and 500 μm or less. The thickness (length L2 or L3, etc.) of the compact portion 95 is, for example, 10 μm or more and 100 μm or less. The loose portion 94 has a diameter greater than the thickness of the tight portion 95. In addition, as described above, the thickness of the dense portion 95 is smaller than the thickness of the dense region 93.
Fig. 5 is a schematic plan view illustrating the porous portion 90 of the electrostatic chuck according to the embodiment.
Fig. 5 shows a part of the porous portion 90 as viewed along the Z direction. Fig. 5 is an enlarged view of the periphery of 1 loose portion 94.
As shown in fig. 5, in this example, the loose portion 94 has: a plurality of holes 96; and a wall portion 97 provided between the plurality of holes 96.
The plurality of holes 96 extend in the Z direction, respectively. The plurality of holes 96 are each in the form of a capillary tube extending in 1 direction (1-dimensional capillary configuration), and penetrate the loose portion 94 in the Z direction. The wall portion 97 is shaped like a wall separating the mutually adjacent holes 96. As shown in fig. 5, when projected onto a plane (XY plane) perpendicular to the Z direction, the wall portion 97 is provided so as to enclose the respective outer circumferences of the plurality of holes 96. The wall portion 97 is continuous with the compact portion 95 at the outer periphery of the loose portion 94.
The number of the holes 96 provided in the 1 loose portion 94 is, for example, 50 or more and 1000 or less. As shown in fig. 5, when projected onto a plane (XY plane) perpendicular to the Z direction, the plurality of holes 96 are substantially the same size as each other. For example, when projected to a plane (XY plane) perpendicular to the Z direction, the plurality of holes 96 are isotropically equally dispersed in the loose portion 94. For example, the distance between adjacent holes 96 (i.e., the thickness of wall 97) is substantially constant.
By arranging the holes 96 extending in 1 direction in the loose portion 94 in this manner, a higher resistance to arc discharge can be achieved with a smaller deviation than in the case where a plurality of holes are randomly dispersed in 3 dimensions in the loose portion.
The "capillary structure" of the plurality of holes 96 is further described herein.
In recent years, miniaturization of circuit line width and miniaturization of circuit pitch have been advanced for the purpose of high integration of semiconductor devices. A higher power is applied to the electrostatic chuck, and it is required to control the temperature of the object W at a higher level. Under such circumstances, it is required to control the flow rate with high accuracy while ensuring a sufficient gas flow rate while reliably suppressing arcing even in a high-power environment. In the electrostatic chuck 110 according to the present embodiment, in a ceramic plug (porous portion 90) that has been conventionally provided to prevent arc discharge in a helium supply hole (gas introduction path 53), the diameter of the hole (diameter of hole 96) is reduced to a level of several micrometers to ten micrometers, for example (the diameter of hole 96 will be described in detail later). If the diameter is reduced up to this level, it may be difficult to control the flow rate of the gas. Thus, in the present invention, for example, the shape of the hole 96 is further studied so as to be in the Z direction. Specifically, conventionally, the flow rate is ensured by a large hole, and the arc discharge is prevented by complicating the shape thereof in 3 dimensions. On the other hand, in the present invention, for example, the diameter of the hole 96 is reduced to a level of several micrometers to ten micrometers to prevent arc discharge, and on the contrary, the flow rate is ensured by simplifying the shape thereof. That is, the present invention has been developed based on a completely different concept from the prior art.
Also, the shape of the loose portion 94 is not limited to a hexagon, but may be a circle (or ellipse) and other polygons. For example, when projection is performed to a plane (XY plane) perpendicular to the Z direction, a smallest circle, ellipse, or polygon including a plurality of holes 96 all arranged at intervals of 10 μm or less is envisaged. The inner side of the circle, ellipse or polygon can be regarded as the loose portion 94 and the outer side of the circle, ellipse or polygon can be regarded as the tight portion 95.
Fig. 6 (a) and (b) are schematic plan views illustrating the porous portion 90 of the electrostatic chuck according to the embodiment.
Fig. 6 (a) and 6 (b) are enlarged views showing a part of the porous portion 90 as viewed along the Z direction, and the holes 96 in 1 loose portion 94.
As shown in fig. 6 (a), when projected onto a plane (XY plane) perpendicular to the Z direction, the plurality of holes 96 have: a hole 96a located at the center of the loose portion 94; and 6 wells 96 (wells 96b to 96 g) surrounding the well 96a. Holes 96 b-96 g are adjacent to hole 96a. The wells 96b to 96g are the wells 96 closest to the well 96a among the plurality of wells 96.
The hole 96b and the hole 96c are aligned with the hole 96a in the X direction. That is, the hole 96a is located between the holes 96b and 96 c.
For example, a length L6 of the hole 96a in the X direction (a diameter of the hole 96 a) is longer than a length L7 of the hole 96a and the hole 96b in the X direction, and longer than a length L8 of the hole 96a and the hole 96c in the X direction.
The length L7 and the length L8 correspond to the thickness of the wall 97, respectively. That is, the length L7 is the length of the wall portion 97 between the holes 96a and 96b in the X direction. The length L8 is the length of the wall portion 97 between the holes 96a and 96c in the X direction. The length L7 can be made substantially the same as the length L8. For example, the length L7 may be set to be 0.5 to 2.0 times the length L8.
The length L6 can be made substantially the same as the length L9 of the hole 96b in the X direction (the diameter of the hole 96 b). The length L6 can be made substantially the same as the length L10 of the hole 96c in the X direction (the diameter of the hole 96 c). For example, the length L9 and the length L10 may be set to be 0.5 times or more and 2.0 times or less, respectively, of the length L6.
For example, if the diameter of the hole is small, the resistance to arc discharge and rigidity are improved. On the other hand, if the diameter of the hole is large, the gas flow rate can be increased. The diameter (length L6, L9, L10, etc.) of the hole 96 is, for example, 1 micrometer (μm) or more and 20 μm or less. By arranging holes with a diameter of 1 to 20 μm extending in 1 direction, a higher resistance to arc discharge can be achieved with a smaller deviation. More preferably, the diameter of the hole 96 is 3 μm or more and 10 μm or less.
Here, a method for measuring the diameter of the hole 96 will be described. Images were obtained with a scanning electron microscope (e.g., hitachi high technology Co., ltd., S-3000) at a magnification of 1000 times or more. Using commercially available image analysis software, diameters corresponding to 100 circles were calculated for the holes 96, and the average value was used as the diameter of the holes 96.
It is further preferable to suppress the diameter variation of the plurality of holes 96. By reducing the diameter variation, the flow rate and the dielectric strength of the flowing gas can be controlled more precisely. As the deviation of the diameters of the plurality of holes 96, cumulative distribution of diameters corresponding to 100 circles obtained in the calculation of the diameters of the holes 96 can be used. Specifically, the concept of the particle diameter D50 (median diameter) at 50vol% of cumulative distribution and the particle diameter D90 at 90vol% of cumulative distribution, which are commonly used in particle size distribution measurement, was applied, and the pore diameter (corresponding to D50 diameter) at 50vol% of cumulative distribution and the pore diameter (corresponding to D90 diameter) at 90vol% of cumulative distribution of the pore diameter were obtained from the cumulative distribution curve of the pores 96 with the pore diameter (μm) on the horizontal axis and the relative pore volume (%). The variation in the diameters of the plurality of holes 96 is preferably suppressed to satisfy D50: d90 is less than or equal to 1:2, the degree of relationship.
The thickness (length L7, L8, etc.) of the wall portion 97 is, for example, 1 μm or more and 10 μm or less. The thickness of the wall portion 97 is thinner than the thickness of the compact portion 95.
As such, the hole 96a adjoins and is enclosed by 6 holes 96 among the plurality of holes 96. That is, when projected onto a plane (XY plane) perpendicular to the Z direction, the number of holes 96 adjacent to 1 hole 96 is 6 at the center portion of the loose portion 94. Thus, the plurality of holes 96 can be arranged with high isotropy and high density in a plan view. This can ensure resistance to arc discharge and a gas flow rate flowing through the through-hole 15, and can improve the rigidity of the porous portion 90. Further, variations in the resistance to arc discharge, variations in the flow rate of the gas flowing through the through-hole 15, and variations in the rigidity of the porous portion 90 can be suppressed.
Fig. 6 (b) shows another example of the arrangement of the plurality of holes 96 in the loose portion 94. As shown in fig. 6 (b), in this example, the plurality of holes 96 are arranged concentrically around the hole 96 a. Thus, when projection is performed on a plane (XY plane) perpendicular to the Z direction, a plurality of holes can be arranged with high isotropy and high density.
The lengths L0 to L10 can be measured by observation using a microscope such as a scanning electron microscope.
The evaluation of the porosity in the present specification will be described. Here, an evaluation of the porosity in the porous portion 90 will be described as an example.
An image as shown in a plan view of fig. 3 (a) is obtained, and the ratio R1 of the porous portion 91 to the plurality of loose portions 94 is calculated by image analysis. Images were taken using a scanning electron microscope (e.g., hitachi high technology Co., S-3000). The acceleration voltage was set to 15kV and the magnification was set to 30 times, so that a BSE image was obtained. For example, the image size is 1280×960 pixels, and the image gradation is 256-level gradation.
The ratio R1 of the porous portions 94 in the porous portion 91 is calculated using image analysis software (for example, win-roover 6.5 (san francisco).
The ratio R1 can be calculated as described below using Win-ROOFVer6.5.
The evaluation range ROI1 (see fig. 3 (a)) is set as a smallest circle (or ellipse) including all the loose portions 94.
Binarization processing based on a single threshold (for example, 0) is performed to calculate the area S1 of the evaluation range ROI 1.
Binarization processing based on 2 threshold values (e.g., 0 and 136) is performed to calculate the total area S2 of the plurality of loose portions 94 in the evaluation range ROI 1. At this time, the hole-filling treatment in the loose portion 94 is performed, and the small area region considered as the disturbance is removed (threshold: 0.002 or less). The 2 thresholds are appropriately adjusted by the brightness and contrast of the image.
The ratio R1 is calculated as the ratio of the area S2 to the area S1. That is, the ratio r1 (%) = (area S2)/(area S1) ×100.
In the embodiment, the ratio R1 of the porous portions 94 in the porous portion 91 is, for example, 40% to 70%, preferably 50% to 70%. The ratio R1 is, for example, about 60%.
An image as shown in the plan view of fig. 5 is obtained, and the proportion R2 of the loose portion 94 occupied by the plurality of holes 96 is calculated by image analysis. The ratio R2 corresponds to, for example, the porosity of the loose portion 94. Images were taken using a scanning electron microscope (e.g., hitachi high technology Co., S-3000). The acceleration voltage was set to 15kV and the magnification was set to 600 times to obtain a BSE image. For example, the image size is 1280×960 pixels, and the image gradation is 256-level gradation.
The proportion R2 of the plurality of holes 96 in the loose portion 94 is calculated using image analysis software (for example, win-roover 6.5 (san francisco).
The ratio R1 can be calculated as described below using Win-ROOFVer6.5.
The evaluation region ROI2 (see fig. 5) is formed in a shape of the loose portion 94 to be approximately hexagonal. The evaluation range ROI2 includes all the holes 96 provided in 1 loose portion 94.
Binarization processing based on a single threshold (for example, 0) is performed to calculate the area S3 of the evaluation range ROI 2.
Binarization processing based on 2 threshold values (e.g., 0 and 96) is performed, and the total area S4 of the plurality of holes 96 in the evaluation range ROI2 is calculated. At this time, the hole-filling process in the hole 96 is performed, and the small area region considered to be a disturbance is removed (threshold: 1 or less). The 2 thresholds are appropriately adjusted by the brightness and contrast of the image.
The ratio R2 is calculated as the ratio of the area S4 to the area S3. That is, the ratio r2 (%) = (area S4)/(area S3) ×100.
In the embodiment, the proportion R2 of the plurality of holes 96 in the loose portion 94 (the porosity of the loose portion 94) is, for example, 20% to 60%, preferably 30% to 50%. The ratio R2 is, for example, about 40%.
The porosity of the porous region 91 corresponds to, for example, a product of a ratio R1 of the plurality of porous portions 94 in the porous region 91 and a ratio R2 of the plurality of holes 96 in the porous portion 94. For example, when the ratio R1 is 60% and the ratio R2 is 40%, the porosity of the porous region 91 can be calculated to be about 24%.
By using the porous portion 90 having the porous region 91 having such a porosity, the insulating strength can be improved while ensuring the gas flow rate flowing through the through-hole 15.
Similarly, the porosities of the ceramic dielectric substrate 11 and the porous portion 70 can be calculated. The magnification of the scanning electron microscope is preferably selected to be in the range of, for example, several tens to several thousands of times in accordance with the observation target.
Fig. 7 (a) and (b) are schematic views illustrating the 1 st porous portion 90 according to another embodiment.
Fig. 7 (a) is a plan view of the porous portion 90 as viewed along the Z direction, and fig. 7 (b) corresponds to an enlarged view of a part of fig. 7 (a).
As shown in fig. 7 (a) and 7 (b), in this example, the planar shape of the loose portion 94 is a circle. As such, the planar shape of the loose portion 94 may also be other than hexagonal.
Fig. 8 is a schematic cross-sectional view illustrating an electrostatic chuck according to an embodiment.
Fig. 8 corresponds to an enlarged view of the region B shown in fig. 2. That is, fig. 8 shows the vicinity of the interface F1 between the porous portion 90 (dense region 93) and the ceramic dielectric substrate 11. In this example, alumina is used as the material of the porous portion 90 and the ceramic dielectric substrate 11.
As shown in fig. 8, the porous portion 90 includes: the 1 st region 90p, which is located on the ceramic dielectric substrate 11 side in the x direction or the Y direction; and a 2 nd region 90q, which is continuous with the 1 st region 90p in the x direction or the Y direction. The 1 st region 90p and the 2 nd region 90q are part of the dense region 93 of the porous portion 90.
The 1 st region 90p is located between the 2 nd region 90q and the ceramic dielectric substrate 11 in the X direction or the Y direction. The 1 st region 90p is a region separated from the interface F1 by about 40 to 60 μm in the X direction or the Y direction. That is, the width W1 of the 1 st region 90p in the X direction or the Y direction (the length of the 1 st region 90p in the direction perpendicular to the interface F1) is, for example, 40 μm or more and 60 μm or less.
The ceramic dielectric substrate 11 further includes: the 1 st substrate region 11p is located on the porous portion 90 (1 st region 90 p) side in the x direction or the Y direction; and a2 nd substrate region 11q, which is continuous with the 1 st substrate region 11p in the x direction or the Y direction. The 1 st region 90p is provided in contact with the 1 st substrate region 11p. The 1 st substrate region 11p is located between the 2 nd substrate region 11q and the porous portion 90 in the X direction or the Y direction. The 1 st substrate region 11p is a region separated from the interface F1 by about 40 to 60 μm in the X direction or the Y direction. That is, the width W2 of the 1 st substrate region 11p in the X direction or the Y direction (the length of the 1 st substrate region 11p in the direction perpendicular to the interface F1) is, for example, 40 μm or more and 60 μm or less.
Fig. 9 (a) and (b) are schematic cross-sectional views illustrating an electrostatic chuck according to an exemplary embodiment.
Fig. 9 (a) is an enlarged view of a part of the 1 st region 90p shown in fig. 8. Fig. 9 (b) is an enlarged view of a part of the 1 st substrate region 11p shown in fig. 8.
As shown in fig. 9 (a), the 1 st region 90p includes a plurality of particles g1 (crystal grains). As shown in fig. 9 b, the 1 st substrate region 11p includes a plurality of particles g2 (crystal grains).
The average particle diameter (average of diameters of the plurality of particles g 1) in the 1 st region 90p is different from the average particle diameter (average of diameters of the plurality of particles g 2) in the 1 st substrate region 11 p.
Since the average particle diameter in the 1 st region 90p is different from the average particle diameter in the 1 st substrate region 11p, the bonding strength (interface strength) between the crystal grains of the porous portion 90 and the crystal grains of the ceramic dielectric substrate 11 can be improved at the interface F1. For example, the porous portion 90 can be prevented from peeling off from the ceramic dielectric substrate 11 and the crystal grains from falling off.
As the average particle diameter, an average value of equivalent circle diameters of crystal grains in the cross-sectional images shown in fig. 9 (a) and 9 (b) can be used. The equivalent circle diameter is a diameter of a circle having the same area as that of the planar shape as the object.
It is also preferable to integrate the ceramic dielectric substrate 11 with the porous portion 90. The porous portion 90 is integrated with the ceramic dielectric substrate 11, and thus can be fixed to the ceramic dielectric substrate 11. This can improve the strength of the electrostatic chuck as compared with the case where the porous portion 90 is fixed to the ceramic dielectric substrate 11 with an adhesive or the like. For example, the electrostatic chuck can be prevented from being aged due to corrosion, ablation, or the like of the adhesive.
In this example, the average particle diameter in the 1 st substrate region 11p is smaller than the average particle diameter in the 1 st region 90 p. Since the particle diameter in the 1 st substrate region 11p is small, the bonding strength between the porous portion 90 and the ceramic dielectric substrate can be improved at the interface between the porous portion 90 and the ceramic dielectric substrate. Further, since the particle size in the 1 st substrate region is small, the strength of the ceramic dielectric substrate 11 can be improved, and the risk of occurrence of cracks or the like due to stress occurring during production and flow can be suppressed. For example, the average particle diameter in the 1 st region 90p is 3 μm or more and 5 μm or less. For example, the average particle diameter in the 1 st substrate region 11p is 0.5 μm or more and 2 μm or less. The average particle diameter in the 1 st substrate region 11p is 1.1 to 5 times the average particle diameter in the 1 st region 90 p.
In addition, for example, the average particle diameter in the 1 st substrate region 11p is smaller than the average particle diameter in the 2 nd substrate region 11 q. In the 1 st substrate region 11p provided in contact with the 1 st region 90p, the interface strength with the 1 st region 90p is preferably improved by interaction such as diffusion with the 1 st region 90 p. On the other hand, in the 2 nd substrate region 11q, the intrinsic characteristics of the material of the ceramic dielectric substrate 11 are preferably exhibited. By making the average particle diameter in the 1 st substrate region 11p smaller than the average particle diameter in the 2 nd substrate region 11q, it is possible to realize both securing of the interface strength in the 1 st substrate region 11p and the characteristics of the ceramic dielectric substrate 11 in the 2 nd substrate region 11 q.
The average particle diameter in the 1 st region 90p may also be smaller than the average particle diameter in the 1 st substrate region 11 p. This can improve the bonding strength between the porous portion 90 and the ceramic dielectric substrate at the interface between the porous portion 90 and the ceramic dielectric substrate. Further, since the average particle diameter in the 1 st region 90p is small, the strength of the porous portion 90 is improved, and therefore, the occurrence of particle fall-off during the flow can be suppressed, and particles can be reduced.
In addition, as in the foregoing, the average particle diameter in the 1 st region 90p may be smaller than the average particle diameter in the 2 nd substrate region 11 q. In this way, the mechanical strength in the 1 st region 90p can be improved.
The structure of the electrostatic chuck 110 will be further described with reference to fig. 2 (a). The electrostatic chuck 110 may further include a porous portion 70 (1 st porous portion, 2 nd porous portion) as described above. The porous portion 70 does not have the plurality of loose portions 94 and the plurality of tight portions 95 described in fig. 3 to 7. In this example, the porous portion 70 is provided on the base plate and is disposed so as to face the gas introduction path 53. The porous portion 70 may be provided between the porous portion 90 and the gas introduction path 53, for example, in the Z direction. For example, the porous portion 70 is embedded in the ceramic dielectric substrate 11 side of the base plate 50. As illustrated in fig. 2 (a), for example, a countersink 53a is provided on the ceramic dielectric substrate 11 side of the base plate 50. The spot facing 53a is provided in a cylindrical shape. The porous portion 70 is fitted into the spot facing portion 53a by appropriately designing the inner diameter of the spot facing portion 53a. As will be described later, the porous portion 70 may be provided on the ceramic substrate 11.
In this example, the upper surface 70U of the porous portion 70 is exposed to the upper surface 50U of the base plate 50. The upper surface 70U of the porous portion 70 faces the lower surface 90L of the porous portion 90. In this example, a space SP is formed between the upper surface 70U of the porous portion 70 and the lower surface 90L of the porous portion 90. The 1 st porous portion can be either the porous portion 90 or the porous portion 70. The 2 nd porous portion may be either the porous portion 90 or the porous portion 70.
The porous portion 70 includes: a porous region 71 (examples of the 1 st porous region and the 2 nd porous region) having a plurality of pores; and dense region 72 (examples of 1 st dense region and 2 nd dense region) is denser than porous region 71. The porous region 71 is provided in a cylindrical shape (for example, a cylindrical shape) and fitted in the spot facing portion 53a. The porous portion 70 is preferably cylindrical in shape, but is not limited to cylindrical. The porous portion 70 is made of an insulating material. The material of the porous portion 70 may be, for example, al 2O3、Y2O3、ZrO2、MgO、SiC、AlN、Si3N4. The material of the porous portion 70 may be glass such as SiO 2. The material of the porous portion 70 may be Al2O3-TiO2、Al2O3-MgO、Al2O3-SiO2、Al6O13Si2、YAG、ZrSiO4 or the like.
The porosity of the porous region 71 is, for example, 20% or more and 60% or less. The density of the porous region 71 is, for example, 1.5g/cm 3 or more and 3.0g/cm 3 or less. The gas such as He flowing through the gas introduction path 53 is sent to the groove 14 from the through-holes 15 provided in the ceramic dielectric substrate 11 through the plurality of holes 71p of the ceramic porous body 71.
The dense region 72 has a portion made of, for example, a ceramic insulating film. The ceramic insulating film is provided between the porous region 71 and the gas introduction path 53. The ceramic insulating film is denser than the porous region 71. The porosity of the ceramic insulating film is, for example, 10% or less. The density of the ceramic insulating film is, for example, 3.0g/cm 3 or more and 4.0g/cm 3 or less. The ceramic insulating film is provided on the side surface of the porous portion 70.
For example, al 2O3、Y2O3、ZrO2, mgO, or the like is used as a material of the ceramic insulating film. Also, Al2O3-TiO2、Al2O3-MgO、Al2O3-SiO2、Al6O13Si2、YAG、Z rSiO4 or the like can be used as the material of the ceramic insulating film.
The ceramic insulating film can be formed on the side surface of the porous portion 70 by sputtering, physical vapor deposition (PVD (Physical Vapor Deposition)), chemical Vapor Deposition (CVD), sol-gel method, aerosol deposition method, or the like, for example. The thickness of the ceramic insulating film is, for example, 0.05mm or more and 0.5mm or less.
The porosity of the ceramic dielectric substrate 11 is, for example, 1% or less. The density of the ceramic dielectric substrate 11 is, for example, 4.2g/cm 3.
As described above, the porosities in the ceramic dielectric substrate 11 and the porous portion 70 were measured by a scanning electron microscope. Density was measured according to JIS (Japanese Industrial Standard) C2141.5.4.3.
When the porous portion 70 is fitted in the countersunk portion 53a of the gas introduction path 53, the ceramic insulating film 72 is in contact with the base plate 50. That is, between the through hole 15 for introducing a gas such as He into the groove 14 and the metal base plate 50, there is a porous portion 70 having a porous region 71 and a dense region 73 with high insulation. By using such porous portion 70, the porous region 71 can exhibit higher insulation than when it is provided only in the gas introduction path 53.
The plurality of holes 71p provided in the porous portion 70 are 3-dimensionally more dispersed than the plurality of holes 96 provided in the porous portion 90, and the ratio of holes penetrating in the Z direction of the porous portion 90 can be made larger than the porous portion 70. Since a higher insulating strength can be obtained by providing the porous portion 70 having the plurality of holes 71p dispersed in 3 dimensions, it is possible to achieve a smooth gas flow and to more effectively suppress the occurrence of arc discharge. Further, as shown in fig. 2 (a), by providing the porous portion 90 having a high proportion of holes penetrating in the Z direction on the ceramic dielectric substrate 11, for example, even when the plasma density is high, the occurrence of arc discharge can be more effectively suppressed.
The average value of the plurality of holes provided in the porous portion (porous portion 2, porous portion 70 in fig. 2 (a)) provided in the base plate 50 can be made larger than the average value of the plurality of holes provided in the porous portion (porous portion 1, porous portion 90 in fig. 2 (a)) provided in the ceramic dielectric substrate 11. In this way, since the porous portion having a large diameter of the hole is provided on the gas introduction path 53 side, the gas flow can be smoothed. Further, since the porous portion having a small pore diameter is provided on the adsorption object side, the occurrence of arc discharge can be more effectively suppressed.
In the case where the porous portion 70 is provided on the base plate 50 and the porous portion 90 is provided on the ceramic dielectric substrate 11, the average value of the diameters of the plurality of holes 71p provided in the porous portion 70 can be made larger than the average value of the diameters of the plurality of holes 96 provided in the porous portion 90. In this way, since the porous portion 70 having a large pore diameter is provided, the gas flow can be smoothed. Further, since the porous portion 90 having a small hole diameter is provided on the adsorption object side, the occurrence of arc discharge can be more effectively suppressed.
In addition, since the variation in diameters of the plurality of holes can be reduced, arcing can be suppressed more effectively.
Fig. 10 is a schematic cross-sectional view illustrating the porous portion 70 of the electrostatic chuck according to the embodiment.
Fig. 10 is an enlarged view of a portion of the cross section of the porous region 71.
Inside the porous region 71, a plurality of holes 71p provided in the porous region 71 are dispersed in 3 dimensions in the X direction, the Y direction, and the Z direction. In other words, the porous region 71 has a 3-dimensional network structure in which the pores 71p diffuse in the X direction, the Y direction, and the Z direction. In the porous portion 70, the plurality of holes 71p are, for example, randomly or uniformly dispersed in the porous region 71.
Since the plurality of holes 71p are dispersed in 3 dimensions, a part of the plurality of holes 71p is also exposed to the surface of the porous region 71. Therefore, fine concave-convex portions are formed on the surface of the porous region 71. That is, the surface of the porous region 71 can be roughened. By the surface roughness of the porous region 71, for example, a ceramic insulating film (dense region 72) can be easily formed on the surface of the porous region 71. For example, the contact of the ceramic insulating film (dense region 72) with the porous region 71 is improved. In addition, peeling of the ceramic insulating film (dense region 72) can be suppressed.
The average value of the diameters of the plurality of holes 71p provided in the porous region 71 is larger than the average value of the diameters of the plurality of holes 96 provided in the porous region 91, for example. The diameter of the hole 71p is, for example, 10 μm or more and 50 μm or less. The porous portion 91 having the small diameter of the hole 96 can control (restrict) the flow rate of the gas flowing through the through hole 15. This can suppress the variation in the gas flow rate caused by the ceramic porous body 71. As described above, the diameter of the hole 71p and the diameter of the hole 96 can be measured by a scanning electron microscope.
Fig. 11 is a schematic cross-sectional view illustrating a porous portion 90 according to another embodiment.
Like fig. 2 (a), fig. 11 illustrates the periphery of the porous portion 90.
In this example, the porous portion 90 is provided on the ceramic dielectric substrate 11. The porous portion 70 is provided on the base plate 50. That is, the 1 st porous portion 90 is used. The porous portion 70 is used as the 2 nd porous portion. The porous portion 90 may be provided on both the ceramic dielectric substrate 11 and the base plate 50.
In this example, an adhesive member 61 (adhesive) is provided between the porous portion 90 and the ceramic dielectric substrate 11. The porous portion 90 is bonded to the ceramic dielectric substrate 11 by the bonding member 61. For example, the adhesive member 61 is provided between the side surface of the porous portion 90 (the side surface 93s of the dense region 93) and the inner wall 15w of the through hole 15. The porous portion 90 may not be in contact with the ceramic dielectric substrate 11.
For example, a silicone adhesive is used as the adhesive member 61. The adhesive member 61 is, for example, an elastic member having elasticity. The elastic modulus of the adhesive member 61 is lower than that of the dense region 93 of the porous portion 90 and lower than that of the ceramic dielectric substrate 11, for example.
In the structure in which the porous portion 90 and the ceramic dielectric substrate 11 are bonded by the adhesive member 61, the adhesive member 61 can be used as a buffer material for a difference between heat shrinkage of the porous portion 90 and heat shrinkage of the ceramic dielectric substrate 11.
Fig. 12 (a) and (b) are schematic cross-sectional views illustrating porous portions 90 according to other embodiments.
In the foregoing embodiment (see fig. 2), the porous portion 90 is provided on the ceramic dielectric substrate 11, and the porous portion 70 is provided on the base plate 50.
However, in the case of using the porous portion 90, any of the porous portion provided on the base plate 50 and the porous portion provided on the ceramic dielectric substrate 11 may be omitted.
For example, in the example shown in fig. 12 (a), the porous portion 90 is provided on the ceramic dielectric substrate 11, and the gas introduction path 53 is provided on the base plate 50. In this way, the flow resistance of the gas such as He supplied to the porous portion 90 can be reduced.
In the example shown in fig. 12 (b), the hole 15b is provided in the ceramic dielectric substrate 11, and the porous portion 90 is provided in the base plate 50. In this way, the flow resistance of the gas such as He supplied to the porous portion 90 can be reduced.
As shown in fig. 12 (a), at least a part of the edge 53b of the opening of the gas introduction path 53 on the ceramic dielectric substrate 11 side can be formed by a curve. For example, the edge 53b of the opening of the gas introduction path 53 may be subjected to so-called "R-surface processing". At this time, the edge 53b of the opening of the gas introduction path 53 can be formed by a curve having a radius of about 0.2 millimeters (mm).
As described above, the base plate 50 is formed of a metal such as aluminum. Therefore, if the edge of the opening of the gas introduction path 53 is relatively sharp, electric field concentration is likely to occur, and arc discharge is likely to occur.
In the present embodiment, since at least a part of the edge 53b of the opening of the gas introduction path 53 is formed by a curve, electric field concentration can be suppressed, so that reduction of arc discharge can be achieved.
Fig. 13 (a) to (d) are schematic cross-sectional views illustrating porous portions 90a and 70a according to other embodiments.
Fig. 14 (a) to (c) are schematic cross-sectional views illustrating porous portions 90a and 90b according to other embodiments.
Fig. 13 (a) shows an example in which a porous portion 90a in which the dense region 93 of the porous portion 90 is changed is provided in the ceramic dielectric substrate 11, and a porous portion 70a in which the dense region 72 of the porous portion 70 is changed is provided in the base plate 50. Fig. 14 (a) shows an example in which a porous portion 90a in which the dense region 93 of the porous portion 90 is changed and a porous portion 70b in which the dense region 72 of the porous portion 70 is changed are provided in the ceramic dielectric substrate 11 and the base plate 50, respectively.
As shown in fig. 13 (a), 13 (b) and 14 (a), the porous region 91 further includes a dense portion 92a in the porous portion 90a provided on the ceramic dielectric substrate 11. That is, the porous portion 90a is a portion where the dense portion 92a is further added to the porous portion 90.
As shown in fig. 13 (a) and 13 (b), the dense portion 92a can be made plate-shaped (for example, disk-shaped). As shown in fig. 14 (a), the dense portion 92a may be columnar (e.g., columnar). The material of the dense portion 92a can be the same as that of the dense region 93 described above, for example. The dense portion 92a is denser than the porous region 91. The density of the densified portion 92a and the densified region 93 may also be the same degree. When projected onto a plane (XY plane) perpendicular to the Z direction, the dense portion 92a overlaps the hole portion 15 b. More preferably, the porous region 91 and the hole 15b are not overlapped. With this structure, the generated current flows around the dense portion 92 a. Therefore, since the distance (conduction path) over which the current flows can be lengthened, electrons are difficult to accelerate, so that the occurrence of arc discharge can be suppressed.
In addition, when projection is performed to a plane (XY plane) perpendicular to the Z direction, it is preferable that the size of the dense portion 92a is the same as the size of the hole portion 15b, or the size of the dense portion 92a is larger than the size of the hole portion 15 b. In this way, the current flowing in the hole 15b can be guided to the dense portion 92 a. Therefore, the distance (conduction path) over which the current flows can be effectively lengthened.
In this example, when projected on a plane perpendicular to the Z direction, a porous region 91 is provided around the dense portion 92 a. Since the dense portion 92a is arranged at a position facing the hole portion 15b to improve the resistance to arc discharge and the periphery thereof is used as the porous region 91, a sufficient gas flow can be ensured. That is, the reduction of arc discharge and the smoothing of gas flow can be simultaneously achieved.
As shown in fig. 13 (a), the length of the dense portion 92a in the Z direction may be smaller than the length of the porous portion 90a in the Z direction, or may be substantially the same as the length of the porous portion 90a in the Z direction, as shown in fig. 14 (a). If the length of the dense portion 92a in the Z direction is lengthened, the occurrence of arcing can be more effectively suppressed. If the length of the dense portion 92a in the Z direction is made smaller than the length of the porous portion 90a in the Z direction, the gas flow can be smoothed.
The dense portion 92a may be formed of a dense body having substantially no holes, or may be formed to have a plurality of holes if it is denser than the porous region 91. When the dense portion 92a has a plurality of holes, the diameter of the holes is preferably made smaller than the diameter of the holes of the porous region 91. The porosity (percentage:%) of the dense portion 92a can be made lower than the porosity (%) of the porous region 91. Thus, the density (g/cc: g/cm 3) of the dense portion 92a can be made higher than the density (g/cm 3) of the porous region 91. The porosity of the dense portion 92a can be made the same as that of the dense region 93 described above, for example.
Here, when a current flows from the ceramic dielectric substrate 11 side toward the base plate 50 side in the hole 15b, arc discharge sometimes occurs. Therefore, if the dense portion 92a having a relatively low porosity is provided in the vicinity of the hole portion 15b, the current 200 flows around the dense portion 92a as shown in fig. 13 (a) and 14 (a). Therefore, since the distance (conduction path) over which the current 200 flows can be lengthened, electrons are difficult to accelerate, so that occurrence of arc discharge can be suppressed.
As shown in fig. 13 (a), for example, a porous portion 70a having a dense portion 92b in the porous region 71 provided in the porous portion 70 of the base plate 50 may be used.
As shown in fig. 14 (a), a porous portion 90a may be provided on the ceramic dielectric substrate 11, and a porous portion 70b may be provided on the base plate 50. The porous region 71 of the porous portion 70b also has a dense portion 92b. That is, the porous portion 70b is a portion where the dense portion 92b is further added to the porous portion 70.
That is, a dense portion 92b may be added to the porous portion 70 or the porous portion 90 provided in the base plate 50.
At least 1 dense portion 92b can be provided. As shown in fig. 13 (c) and 14 (b), a plurality of dense portions 92b may be provided in a plate shape (for example, a disk shape) or a columnar shape (for example, a columnar shape). As shown in fig. 13 (d) and 14 (c), a dense portion 92b may be provided in a ring shape (for example, a circular ring shape) or a tubular shape (for example, a tubular shape). The material, density, porosity, and the like of the dense portion 92b can be made the same as those of the dense portion 92 a.
When projection is performed on a plane (XY plane) perpendicular to the Z direction, it is preferable that at least a part of the dense portion (for example, dense portion 92 b) of the porous portion provided on the base plate 50 is overlapped with the dense portion (for example, dense portion 92 a) of the porous portion provided on the ceramic dielectric substrate 11. According to such a configuration, for example, when the current flowing through the dense portion 92a by bypassing the dense portion 90a (porous portion on the ceramic dielectric substrate 11 side) flows through the porous portions 70 and 90b (porous portion on the base plate 50 side) provided in the dense portion 92b, the current does not flow through the porous regions (for example, the porous regions 71 and 91) of the porous portion provided on the base plate 50 side, but flows through the dense portion 92 b. Therefore, since the distance (conduction path) over which the current flows can be further lengthened, electrons are further difficult to accelerate, so that the occurrence of arc discharge can be effectively suppressed.
Fig. 15 (a) and (b) are schematic cross-sectional views illustrating porous portions according to other embodiments.
As shown in fig. 15 (a) and (b), when projected on a plane (XY plane) perpendicular to the Z direction, the dense portion 92a and the dense portion 92b can be overlapped. In addition, when projection is performed to a plane (XY plane) perpendicular to the Z direction, the dense portion 92a may be brought into contact with the dense portion 92 b. When the projection is performed on a plane (XY plane) perpendicular to the Z direction, if the gap between the dense portion 92a and the dense portion 92b is small, it is possible to suppress the flow of current between the dense portion 92a and the dense portion 92 b. Therefore, if the current can be suppressed from flowing between the dense portion 92a and the dense portion 92b, a gap may be provided between the dense portion 92a and the dense portion 92 b.
In this way, the current flowing through the porous portion 90a can be suppressed from flowing through the porous portion 70a without passing through the dense portion 92 b. Therefore, the distance (conduction path) over which the current flows can be effectively lengthened.
As shown in fig. 15 (a) and (b), when the projection is performed on a plane (XY plane) perpendicular to the Z direction, it is preferable that the dense portion 92b overlaps the dense region 93. In addition, when projection is performed to a plane (XY plane) perpendicular to the Z direction, the dense portion 92b may be brought into contact with the dense region 93. In this way, since the distance (conduction path) over which the current flows can be further lengthened, electrons are further difficult to accelerate, so that the occurrence of arc discharge can be effectively suppressed.
Fig. 16 is a schematic cross-sectional view illustrating an electrostatic chuck according to another embodiment.
Fig. 17 (a) and (b) are enlarged views corresponding to the region C shown in fig. 16.
As shown in fig. 16 and fig. 17 (a) and (b), the electrostatic chuck 110a includes a ceramic dielectric substrate 11c and a base plate 50. That is, the ceramic dielectric substrate 11c is not provided with a porous portion (the porous portion 70 or the porous portion 90).
The ceramic dielectric substrate 11c is directly provided with a plurality of holes 16. The plurality of holes 16 can be formed in the ceramic dielectric substrate 11c by, for example, laser irradiation, ultrasonic processing, or the like. In this example, one end of the plurality of holes 16 is located at the face 14a of the slot 14. The other ends of the plurality of holes 16 are located on the 2 nd main surface 11b of the ceramic dielectric substrate 11c. That is, the plurality of holes 16 penetrate the ceramic dielectric substrate 11c in the Z direction.
As shown in fig. 17 (a) and (b), a porous portion (for example, a porous portion 70 a) may be provided in the base plate 50. The porous portion 90b may be provided in the base plate 50. As illustrated in fig. 12 (a), the gas introduction path 53 may be provided in the base plate 50 instead of the porous portion 70 or the porous portion 90.
As shown in fig. 17 (a) and (b), the upper surface 70U of the porous portion 70 (or the upper surface 90U of the porous portion 90) provided on the base plate 50 may not be in contact with the 2 nd main surface 11b of the ceramic dielectric substrate 11 c. In addition, as in the above, at least a part of the edge 53b of the opening on the ceramic dielectric substrate 11c side of the gas introduction path 53 may be formed by a curved line.
If the plurality of holes 16 are provided in the ceramic dielectric substrate 11c, the resistance to arc discharge can be improved while ensuring the flow rate of gas supplied between the back surface of the object W placed on the electrostatic chuck 110a and the 1 st main surface 11a including the groove 14.
The length of the dense portion 92b in the Z direction can be made smaller than the lengths of the porous portions 70a, 90b in the Z direction. The length of the dense portion 92b in the Z direction may be substantially the same as the lengths of the porous portions 70a and 90b in the Z direction. If the length of the dense portion 92b in the Z direction is shortened, the gas flow can be smoothed. If the length of the dense portion 92b in the Z direction is lengthened, the occurrence of arcing can be more effectively suppressed.
When projected to a plane (XY plane) perpendicular to the Z direction, at least 1 of the plurality of holes 16 may be overlapped with the dense portion 92 b. The material, density, porosity, and the like of the plurality of dense portions 92b are, for example, the same as those described above.
As shown in fig. 17 (a), a porous portion 70a having a plurality of dense portions 92b may be provided on the base plate 50. As shown in fig. 17 (b), a porous portion 90b having a plurality of dense portions 92b may be provided on the base plate 50.
Fig. 18 is a schematic cross-sectional view illustrating a plurality of holes 16h according to another embodiment.
The plurality of holes 16h can be formed in the ceramic dielectric substrate 11 by laser irradiation, ultrasonic processing, or the like.
As shown in fig. 18, at least 1 of the plurality of holes 16h provided in the ceramic dielectric substrate 11 may have: a1 st portion 16h1 opening to the groove portion 14; and a2 nd portion 16h2 opening to the 2 nd main surface 11 b. The size of the 1 st portion 16h1 can be made smaller than the size of the 2 nd portion 16h2 in the X direction or the Y direction. In the X-direction or the Y-direction, the opening dimension D4 on the surface 14a side of the groove 14 of at least 1 of the plurality of holes 16h can be made smaller than the opening dimension D3 on the base plate 50 side. Further, although the hole 16h having a stepped structure is illustrated in fig. 18, the hole 16h having a tapered structure may be formed. For example, the diameter of the opening dimension D4 can be set to 0.01 millimeters (mm) to 0.1 mm. For example, the diameter of the opening D3 can be set to about 0.15 millimeters (mm) to about 0.2 mm. If the opening size D4 is smaller than the opening size D3, the occurrence of arc discharge can be effectively suppressed.
The aspect ratio (aspect ratio) of the hole 16h can be set to, for example, 3 to 60. In the calculation of the aspect ratio, for example, "vertical" is taken as the Z-direction length of the hole 16h in fig. 18, and "horizontal" is taken as the average length of the X-direction length of the hole 16h on the upper surface (surface 14 a) and the X-direction length of the hole 16h on the lower surface (2 nd main surface 11 b) of the hole 16 h. In addition, for measurement of the length of the hole 16h in the X direction, an optical microscope such as a laser microscope or an industrial microscope, a digital microscope, or the like can be used.
In addition, the opening dimension D4 can be made smaller than the length L1 of the loose portion 94a (the length L4 of the loose portion 94b, the length L5 of the loose portion 94 c) illustrated in fig. 4.
Fig. 19 (a) and (b) are schematic cross-sectional views illustrating the shape of the opening portion of the hole 16.
Fig. 19 (b) corresponds to an enlarged view of the region D shown in fig. 19 (a). In fig. 19 (a), the portion of the opening dimension D3 of fig. 18 is not present in the hole 16. That is, the opening size of the hole 16 corresponds to the opening size D4 in fig. 18.
As shown in fig. 19 (a) and (b), the edge 16i of the opening on the 1 st main surface 11a side (the surface 14a side of the groove 14) of the hole 16 can be inclined more gently than the edge 16j of the opening on the 2 nd main surface 11b side of the hole 16. In this example, at least 1 of the plurality of holes 16 is "α < β" when α is defined as an angle formed by an edge 16i of the opening of the hole 16 on the side of the groove 14 and a surface 14a of the groove 14 on the side of the 2 nd main surface 11b, and β is defined as an angle formed by an edge 16j of the opening of the hole 16 on the side of the 2 nd main surface 11b and the 2 nd main surface 11 b. In this way, the occurrence of electric field concentration can be suppressed, so that reduction in arc discharge can be achieved. Also, in this example, the edge 16i is formed by a straight line. The edges 16i may be formed by curves, but may also be formed by straight lines and curves. When the edges 16i and 16j are formed by curves, the radius of curvature of the edge 16i can be made larger than the radius of curvature of the edge 16 j. When the edges 16i and 16j are formed of straight lines and curved lines, at least one of the relationship between the straight line portions and the relationship between the curved line portions may satisfy the above-described relationship.
If the edge 16i is inclined more gently than the edge 16j, the occurrence of inclination and the like and electric field concentration can be suppressed. Therefore, the occurrence of arc discharge can be more effectively suppressed.
Also, as an example, the shape of the opening portion of the hole 16 is exemplified, but the same applies to the case of the hole 16h having a stepped structure or a tapered structure.
Fig. 20 is a schematic cross-sectional view illustrating an electrostatic chuck according to another embodiment.
Fig. 20 corresponds to an enlarged view of the region C shown in fig. 16.
The plurality of holes 16 illustrated in fig. 17 (a) extend in the substantially Z direction, respectively. In contrast, at least 1 of the plurality of holes 16 illustrated in fig. 20 can be inclined to the Z direction. If at least 1 of the plurality of holes 16 extends in a direction oblique to the Z direction, electrons are considered to be difficult to accelerate when a current flows inside the holes 16. Therefore, the occurrence of arc discharge can be effectively suppressed. According to the knowledge obtained by the present inventors, if the angle θ inclined to the Z direction is set to 5 ° or more and 30 ° or less, preferably 5 ° or more and 15 ° or less, the occurrence of arc discharge can be suppressed without reducing the diameter of the hole 16.
Also, as an example, the case of the hole 16 is illustrated, but the same applies to the case of the hole 16h having a stepped structure or a tapered structure.
The holes 16 inclined to the Z direction can be directly formed in the ceramic dielectric substrate 11c by laser irradiation, ultrasonic processing, or the like. Therefore, the region where at least 1 hole 16 inclined to the Z direction is provided contains the same material as the ceramic dielectric substrate 11.
Fig. 21 is a schematic cross-sectional view illustrating an electrostatic chuck according to another embodiment.
Fig. 21 corresponds to an enlarged view of the region C shown in fig. 16.
As shown in fig. 21, the porous region 91 of the porous portion 90b further has a dense portion 92b. That is, the porous portion 90b is a portion where the dense portion 92b is further added to the porous portion 90. That is, a dense portion 92b may be added to the porous portion 70 or the porous portion 90 provided in the base plate 50.
When projected onto a plane (XY plane) perpendicular to the Z direction, at least 1 of the openings on the dense portion 92b side of the plurality of holes 16 can be overlapped with the dense portion 92 b. The material, density, porosity, and the like of the plurality of dense portions 92b are, for example, the same as those described above.
Fig. 22 is a schematic cross-sectional view illustrating an electrostatic chuck according to another embodiment.
Fig. 23 is an enlarged view of the area E shown in fig. 22.
Fig. 24 is an enlarged view showing another embodiment of the region E shown in fig. 22.
As shown in fig. 22, 23, and 24, the electrostatic chuck 110b includes a ceramic dielectric substrate 11d and a base plate 50. The ceramic dielectric substrate 11d is provided with a porous portion 90b or a porous portion 90a.
The ceramic dielectric substrate 11d is provided with a plurality of holes 16. The plurality of holes 16 can be formed in the ceramic dielectric substrate 11d by, for example, laser irradiation, ultrasonic processing, or the like. In this example, one end of the plurality of holes 16 is located at the face 14a of the slot 14. The other ends of the plurality of holes 16 are located at the bottom surface of the hole portion 15 c. That is, the plurality of holes 16 penetrate the ceramic dielectric substrate 11d in the Z direction.
As shown in fig. 23, when projected onto a plane (XY plane) perpendicular to the Z direction, at least 1 of the plurality of holes 16 can be overlapped with the dense portion 92 b. The material, density, porosity, etc. of the dense portion 92b are, for example, the same as those described above.
As shown in fig. 24, when projected onto a plane (XY plane) perpendicular to the Z direction, at least 1 of the plurality of holes 16 can be overlapped with the dense portion 92 a. The material, density, porosity, etc. of the dense portion 92a are, for example, the same as those described above.
Processing device
Fig. 25 is a schematic diagram illustrating a processing device 200 according to the present embodiment.
As shown in fig. 25, the processing apparatus 200 may be provided with an electrostatic chuck 110, a power supply 210, a medium supply unit 220, and a supply unit 230.
The power supply 210 is electrically connected to the electrode 12 provided to the electrostatic chuck 110. The power supply 210 can be, for example, a dc power supply. The power supply 210 applies a predetermined voltage to the electrode 12. In addition, a switch for switching between application of the voltage and application of the stop voltage may be provided to the power supply 210.
The medium supply unit 220 is connected to the input path 51 and the output path 52. The medium supply unit 220 can supply a liquid composed of a cooling medium or a heat-insulating medium, for example.
The medium supply unit 220 includes, for example, a housing unit 221, a control valve 222, and a discharge unit 223.
The storage unit 221 can be, for example, a tank for storing liquid, a factory piping, or the like. Further, a cooling device or a heating device for controlling the temperature of the liquid may be provided in the housing portion 221. The housing 221 may further include a pump or the like for delivering the liquid.
The control valve 222 is connected between the input path 51 and the housing 221. The control valve 222 can control at least one of the flow rate and the pressure of the liquid. In addition, the control valve 222 may be configured to switch between supply and stop supply of the liquid.
The discharge portion 223 is connected to the output path 52. The discharge portion 223 can be a tank, a drain pipe, or the like for collecting the liquid discharged from the output passage 52. The discharge portion 223 is not necessarily required, and the liquid discharged from the output passage 52 may be supplied to the storage portion 221. In this way, the cooling medium or the heat-insulating medium can be circulated, and thus, resource saving can be achieved.
The supply unit 230 includes a gas supply unit 231 and a gas control unit 232.
The gas supply unit 231 can be a high-pressure bottle or a factory piping for housing a gas such as helium. Although the case where 1 gas supply portion 231 is provided is illustrated, a plurality of gas supply portions 231 may be provided.
The gas control unit 232 is connected between the plurality of gas supply paths 53 and the gas supply unit 231. The gas control unit 232 can control at least one of the gas flow rate and the gas pressure. The gas control unit 232 may also have a function of switching between supply and stop of the gas. The gas control unit 232 may be, for example, a Mass Flow controller (Mass Flow Controller) or a Mass Flow Meter (Mass Flow Meter).
As shown in fig. 25, a plurality of gas control units 232 can be provided. For example, the gas control portion 232 may be provided in each of a plurality of regions of the 1 st main surface 11 a. In this way, the control of the gas supply can be performed in each of the plurality of regions. In this case, the gas control unit 232 may be provided in each of the plurality of gas supply paths 53. In this way, gas control in a plurality of regions can be performed more precisely. Although the case where the plurality of gas control units 232 are provided is exemplified, 1 gas control unit 232 may be used if it is capable of independently controlling the gas supply in the plurality of supply systems.
Here, there are vacuum chucks, mechanical chucks, and the like in the method of holding the object W. But the vacuum chuck cannot be used in an environment where the pressure is reduced more than the atmospheric pressure. In addition, if a mechanical chuck is used, there is a possibility that the object W is damaged or particles are generated. For this reason, for example, an electrostatic chuck is used in a processing apparatus used in a semiconductor manufacturing process or the like.
In such a processing apparatus, it is necessary to isolate the processing space from the external environment. Thus, the processing device 200 may also have a chamber 240. The chamber 240 can have an airtight structure that can maintain, for example, an atmosphere that is depressurized more than atmospheric pressure.
The processing apparatus 200 may further include a plurality of lift pins and a driving device for lifting and lowering the plurality of lift pins. When receiving the object W from the conveying device or transferring the object W to the conveying device, the lift pins are raised by the driving device and protrude from the 1 st main surface 11 a. When the object W received from the conveying device is placed on the 1 st main surface 11a, the lift pins are lowered by the driving device and accommodated in the ceramic dielectric substrate 11.
In addition, various devices can be provided in the processing device 200 in accordance with the processing contents. For example, a vacuum pump or the like that exhausts the interior of the chamber 240 may be provided. A plasma generating device that generates plasma inside the chamber 240 can be provided. A process gas supply unit that supplies a process gas into the chamber 240 can be provided. A heater that heats the object W or the process gas can be provided in the chamber 240. The device provided in the processing device 200 is not limited to the illustrated one. Since a known technique can be applied to the apparatus provided in the processing apparatus 200, a detailed description thereof will be omitted.
The embodiments of the present invention have been described above. The present invention is not limited to the above. For example, a structure using coulomb force is exemplified as the electrostatic chuck 110, but a structure using johnson-type radson-type force may be applied. In addition, the foregoing embodiments are also included in the scope of the present invention as long as the features of the present invention are provided, and those skilled in the art can appropriately design and modify the present invention. The elements of the embodiments described above may be combined as long as the technology is technically feasible, and the combined technology is also included in the scope of the present invention as long as the technology includes the features of the present invention.
Claims (17)
1. An electrostatic chuck is provided with: a ceramic dielectric substrate having a1 st main surface on which an object to be adsorbed is placed, a2 nd main surface on the opposite side of the 1 st main surface, and at least 1 groove opening to the 1 st main surface;
A base plate which supports the ceramic dielectric substrate and has a gas introduction path;
and a1 st porous portion provided between the tank and the gas introduction path, characterized in that,
The ceramic dielectric substrate has a plurality of holes communicating the grooves and the gas introduction path, and penetrates the ceramic dielectric substrate in a1 st direction from the base plate toward the ceramic dielectric substrate,
The 1 st porous portion has: at least 1 porous region having a plurality of pores; and at least 1 dense region denser than the porous region, the porous region further having at least 1 dense portion configured to be provided with the porous region therearound when projected to a plane perpendicular to the 1 st direction,
When projected onto a plane perpendicular to the 1 st direction, at least 1 of the plurality of holes provided in the ceramic dielectric substrate is configured to overlap at least 1 of the dense portions.
2. The electrostatic chuck of claim 1, wherein the 1 st porous portion is disposed on the ceramic dielectric substrate.
3. An electrostatic chuck according to claim 1 or 2, wherein,
Further comprises a2 nd porous portion provided between the groove and the gas introduction path,
The 2 nd porous portion is provided on the base plate.
4. The electrostatic chuck of claim 1, wherein the 1 st porous portion is disposed on the base plate.
5. An electrostatic chuck according to claim 1 or 2, wherein,
The porous region has: a plurality of loose portions having a plurality of holes; and a dense portion having a density higher than that of the loose portion, a dimension in a2 nd direction orthogonal to the 1 st direction being smaller than a dimension of the dense region in the 2 nd direction,
The plurality of loose portions extend in the 1 st direction respectively,
The tight portion is located between each other of the plurality of loose portions,
The loose portion has wall portions disposed between each other of the plurality of holes,
In the 2 nd direction orthogonal to the 1 st direction, a minimum value of the dimension of the wall portion is smaller than a minimum value of the dimension of the compact portion.
6. The electrostatic chuck of claim 5, wherein the plurality of holes respectively provided in the plurality of loose portions in the 2 nd direction have a smaller size than the tight portion.
7. The electrostatic chuck of claim 5, wherein the aspect ratio of the plurality of holes respectively provided in the plurality of loose portions is 30 or more.
8. The electrostatic chuck of claim 5, wherein the plurality of holes respectively provided in the plurality of loose portions in the 2 nd direction have a size of 1 micron or more and 20 microns or less.
9. The electrostatic chuck according to claim 5, wherein,
The plurality of holes includes a1 st hole located at a center portion of the loose portion when viewed along the 1 st direction,
Of the plurality of holes, the number of holes adjacent to the 1 st hole and surrounding the 1 st hole is 6.
10. The electrostatic chuck according to claim 1 or 2, wherein a length of the dense portion in the 1 st direction is smaller than a length of the 1 st porous portion in the 1 st direction.
11. The electrostatic chuck according to claim 1 or 2, wherein a length of the dense portion in the 1 st direction is the same as a length of the 1 st porous portion in the 1 st direction.
12. The electrostatic chuck according to claim 1 or 2, wherein at least a part of an edge of the opening of the gas introduction path on the ceramic dielectric substrate side is formed by a curve.
13. An electrostatic chuck according to claim 1 or 2, wherein,
At least 1 of the plurality of holes provided in the ceramic dielectric substrate has: part 1, open to the trough; and a 2 nd portion connected to the 1 st portion and opened to the 2 nd main surface,
In a2 nd direction orthogonal to the 1 st direction, the 1 st portion has a smaller size than the 2 nd portion.
14. The electrostatic chuck according to claim 1 or 2, wherein at least 1 of the plurality of holes provided in the ceramic dielectric substrate satisfies α < β when an angle formed by an edge of an opening of the hole on the groove side and a bottom surface of the groove is α and an angle formed by an edge of an opening of the hole on the 2 nd main surface side and the 2 nd main surface is β.
15. The electrostatic chuck of claim 1 or 2, wherein at least 1 of the plurality of holes provided in the ceramic dielectric substrate is inclined to the 1 st direction.
16. The electrostatic chuck of claim 15, wherein the angle oblique to the 1 st direction is 5 ° or more and 30 ° or less.
17. A processing device is characterized in that,
The device is provided with: the electrostatic chuck according to any one of claims 1 to 16;
and a supply unit configured to supply a gas to a gas introduction path provided in the electrostatic chuck.
Applications Claiming Priority (4)
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| JP2019-039864 | 2019-03-05 | ||
| JP2019039864 | 2019-03-05 | ||
| JP2020013663A JP7441404B2 (en) | 2019-03-05 | 2020-01-30 | Electrostatic chuck and processing equipment |
| JP2020-013663 | 2020-01-30 |
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| CN109037096A (en) * | 2017-06-09 | 2018-12-18 | 三星电子株式会社 | The method of electrostatic chuck, plasma processing apparatus and manufacturing semiconductor devices |
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| JP5633766B2 (en) * | 2013-03-29 | 2014-12-03 | Toto株式会社 | Electrostatic chuck |
| US9805963B2 (en) * | 2015-10-05 | 2017-10-31 | Lam Research Corporation | Electrostatic chuck with thermal choke |
| US10770270B2 (en) * | 2016-06-07 | 2020-09-08 | Applied Materials, Inc. | High power electrostatic chuck with aperture-reducing plug in a gas hole |
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