CN110942969B

CN110942969B - Gas shower head assembly and plasma processing equipment thereof

Info

Publication number: CN110942969B
Application number: CN201811108496.9A
Authority: CN
Inventors: 杨金全; 徐朝阳; 倪图强
Original assignee: Advanced Micro Fabrication Equipment Inc Shanghai
Current assignee: Advanced Micro Fabrication Equipment Inc Shanghai
Priority date: 2018-09-21
Filing date: 2018-09-21
Publication date: 2022-08-23
Anticipated expiration: 2038-09-21
Also published as: CN110942969A

Abstract

The invention discloses a gas shower head assembly, comprising: the device comprises a mounting base, a heat conducting pad, a grounding ring and a gas spray head; a heat conducting pad is arranged between the grounding ring and the mounting base, and the three parts are fixed together; a heat conducting pad is arranged between the gas spray head and the mounting base, and the three parts are fixed together; the method is characterized in that: the thermal pad includes: the heat conduction structure comprises a first Teflon material layer, a first heat conduction layer, a heat conduction support layer, a second heat conduction layer and a second Teflon material layer which are sequentially stacked; and plasma processing apparatus employing the gas showerhead assembly.

Description

Gas shower head assembly and plasma processing equipment thereof

Technical Field

The invention relates to the field of semiconductor equipment, in particular to a gas spray head assembly and plasma processing equipment thereof.

Background

During some semiconductor processes, a substrate or wafer is processed by a substrate processing apparatus. For example, substrate processing apparatuses are used to process substrates, such as semiconductor, glass, or polymer substrates, by techniques including etching, Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD), Plasma Enhanced Chemical Vapor Deposition (PECVD), Atomic Layer Deposition (ALD), Plasma Enhanced Atomic Layer Deposition (PEALD), Pulsed Deposition Layer (PDL), Plasma Enhanced Pulsed Deposition Layer (PEPDL), resist removal. When a wafer or a substrate is subjected to a plasma etching process in an etching chamber of Inductively Coupled Plasma (ICP) or Capacitively Coupled Plasma (CCP), a process gas is allowed to enter the chamber through a showerhead provided in the chamber, and a vibrating electric energy of a Radio Frequency (RF) is applied to the chamber to excite the gas into a plasma. The gas reacts with the surface of the substrate or wafer exposed to the plasma to form a film on the wafer or to clean the substrate or wafer from the components of the process gas.

In the prior art, a gas spray header is made of monocrystalline silicon or silicon carbide material. A ground ring is installed at the periphery of the gas shower head for implementing a Radio Frequency (RF) signal loop. The gas spray header is fixed together with the mounting base through screws or attaching agents, and a heat conduction pad needs to be added between the contact surfaces of the two parts to help improve the contact area, so that the temperature of the gas spray header can be adjusted conveniently, and a Radio Frequency (RF) signal loop is not influenced. However, in the prior art, the traditional heat conducting pad between the gas spray head and the mounting base has two disadvantages, the first one is that the mounting base and the gas spray head are made of different materials, and under different working temperatures of the etching cavity, the two materials slide relatively due to different thermal expansion coefficients, so that the contact surface of the heat conducting pad is abraded, particles are generated, and when the particles enter a process gas path of the gas spray head assembly, the particles float to the surface of a wafer along with air flow or fall into a plasma environment of the cavity, so that particle pollution is generated on the wafer, the quality of the plasma etching wafer is damaged, and the processing rate is influenced. The second disadvantage is that the surface material of the conventional heat conducting pad becomes sticky after being used for a period of time under a high-temperature environment, which is not beneficial to the disassembly and maintenance of the gas spray header and increases the cost.

Disclosure of Invention

The invention aims to provide a gas shower head assembly and plasma processing equipment thereof, which can effectively reduce particles generated by abrasion of a heat conducting pad and prevent wafers from being polluted. In addition, the surface of the heat conducting pad is smooth, so that the disassembly and maintenance of the gas spray head are facilitated, and the cost is reduced.

In order to achieve the above purpose, the invention is realized by the following technical scheme:

the first technical scheme of the invention is as follows: a gas showerhead assembly, comprising: the device comprises a mounting base, a heat conducting pad, a grounding ring and a gas spray head; heat conducting pads are arranged between the grounding ring and the mounting base as well as between the gas spray header and the mounting base, and the three parts are fixed together; the method is characterized in that: a thermal pad, comprising: the heat conduction device comprises a first Teflon material layer, a first heat conduction layer, a heat conduction supporting layer, a second heat conduction layer and a second Teflon material layer which are sequentially stacked.

Preferably, the thermally conductive support layer is composed of a hard material.

Preferably, the hard material comprises one or more of gold, silver, aluminum, or stainless steel.

Preferably, the first and second soft heat conduction layers comprise one or a mixture of graphite and heat conduction silica gel.

Preferably, the sides of said first and second layers of Teflon material, first and second layers of heat conducting layer and thermally conductive support layer are provided with a third layer of Teflon material.

Preferably, the first Teflon material layer comprises one or more of PTFE, FEP, PFA or ETFE.

Preferably, the second Teflon material layer comprises one or more of PTFE, FEP, PFA or ETFE.

Preferably, the third Teflon material layer comprises one or more than two of PTFE, FEP, PFA or ETFE

Preferably, the first and second layers of Teflon material can withstand between 150 degrees Celsius and 260 degrees Celsius.

Preferably, the third layer of Teflon material can withstand between 150 degrees Celsius and 260 degrees Celsius.

Preferably, the first and second layers of Teflon material have a thickness between 5 and 70 microns.

Preferably, the thickness of the third Teflon material layer is between 5 and 70 micrometers

The second technical scheme of the invention is as follows: a plasma processing apparatus, comprising: the reaction cavity is defined by the outer wall, and the base is arranged in the reaction cavity and used for supporting the substrate to be processed; the gas supply device is connected with the reaction cavity and used for conveying reaction gas into the reaction cavity through the gas spray head assembly, and the gas spray head assembly comprises a mounting base, a cooling pipeline, a heating element, a heat conducting pad, a grounding ring and a gas spray head.

The third technical scheme of the invention is as follows: a method for manufacturing a gas shower head assembly, comprising the steps of providing a mounting base having cooling lines and heating elements disposed therein, providing a thermal pad between the mounting base and a ground ring, and between the mounting base and a gas shower head, and processing the thermal pad by: the method comprises the steps of respectively arranging a first heat conduction layer and a second heat conduction layer on the upper surface and the lower surface of a heat conduction support layer, smearing Teflon material solution on the surfaces of the first heat conduction layer and the second heat conduction layer, solidifying, repeatedly smearing and solidifying to form a Teflon material layer with a specified thickness, wherein the Teflon material layer has the characteristics of high temperature resistance, wear resistance and no viscosity.

Preferably, the first and second Teflon material layers, the first and second heat-conducting layers and the heat-conducting support layer are coated with Teflon material solution and cured, and the coating and curing steps are repeated to form a third Teflon material layer with a specified thickness.

Compared with the prior art, the invention has the following advantages:

according to the invention, through the laminated arrangement of the heat conducting pads used in the gas spray head assembly, the heat conduction is improved, and meanwhile, when the gas spray head and the mounting base slide relatively due to different thermal expansion coefficients, the generation of particles on the surface of the heat conducting pad can be effectively reduced, so that the pollution of the particles on the surface of the wafer can be prevented, and meanwhile, because the surface of the heat conducting pad is smooth and non-adhesive, the gas spray head can be conveniently disassembled from the mounting base when the gas spray head is replaced, and the cost is reduced.

Drawings

FIG. 1 is a schematic sectional view showing the main components of a plasma processing apparatus according to the present invention;

FIG. 2 is a schematic cross-sectional view of a gas showerhead assembly of the present invention;

FIG. 3 is a schematic cross-sectional view of a thermal pad according to the present invention;

fig. 4 is a schematic cross-sectional view of a thermal pad according to another embodiment of the present invention.

Detailed Description

The invention will be further described by the detailed description of two preferred embodiments in conjunction with the drawings.

As shown in fig. 1, a plasma processing apparatus of the present invention is disclosed, comprising: a gas showerhead assembly 400, an electrostatic chuck 120, a Radio Frequency (RF) power supply 126, and a process chamber wall 124; the gas shower head assembly 400 is in the shape of an inverted disk on the side opposite to the electrostatic chuck 120, wherein a plurality of gas injection holes 416 are annularly distributed on the flat surface of the gas shower head assembly 400, and each gas injection hole penetrates through the gas shower head assembly 400 and is used for providing process gas into the reaction chamber. Process gas flows from gas source 102 through gas line 103 and into gas showerhead assembly 400. The gas shower head assembly 400 includes: mounting base 104, cooling lines 112, heating element 114, thermal pad 106, ground ring 108, and gas showerhead 110; a heat conducting pad 106 is arranged between the mounting base 104 and the gas shower head 110, and the heat conducting pad 106 is arranged in a stacked mode; the process gas is excited into a plasma 118 in a process chamber 119 defined by a process chamber wall 124 by a Radio Frequency (RF) power supply 126 applied to an electrostatic chuck 120, and processes the surface of the wafer 116 by a Radio Frequency (RF) electric field. The exhaust gas is pumped out of the process chamber 119 through an exhaust line 127 by a gas pump 128. additionally, the gas pressure in the process chamber 119 can be adjusted by the gas pump 128.

As shown in fig. 2, there is a schematic view of the gas shower head assembly 400 of the present invention and a single process gas circuit 500. The cooling pipeline 112 and the heating element 114 are arranged in the mounting base 104 and used for controlling the temperature of the gas spray header 110, the heating element 114 can emit heat after being electrified through cooling liquid with specified temperature in the cooling pipeline 112, and the heating element and the cooling pipeline can work simultaneously, so that the purposes of adjusting the temperature and controlling the temperature uniformity of the gas spray header 110 can be achieved. An air passage 410 is provided on the mounting base 104, the air passage 410 may be a through hole or a groove, and penetrates from the upper surface 104a to the first lower surface 104b of the mounting base 104, and the first lower surface 104b is lower than the second lower surface 104c in the vertical direction, and the first lower surface 104b and the second lower surface 104c are connected by a sidewall 105, the first lower surface 104c and the sidewall 107 of the adjacent air passage 420, and a common groove is used for mounting the groove of the thermal pad 106. The top surface 106a of the thermal pad 106 contacts the second bottom surface 104c of the mounting base, the bottom surface 106b of the thermal pad 106 contacts the top surface 110a of the showerhead 110 or the top surface 108a of the ground ring, thereby conducting heat and Radio Frequency (RF) return signals between the mounting base 104 and the showerhead 110, and between the mounting base 104 and the ground ring 108, the side 106c of the thermal pad 106 contacts the sidewall 105, and the sidewall 105 prevents the sidewall 106c of the thermal pad from directly contacting the process gas, reducing particles on the thermal pad 106 from being carried by the process gas to the interior of the process chamber 119. The mounting base 104, the thermal pad 106, and the gas showerhead 110 are coupled together by screws 402. A ground ring 108 is disposed about the periphery of the gas showerhead assembly 400 and is coupled to the thermal pad 106 and the mounting base 104 by screws 402. To ensure good thermal contact between the thermal pad 106 and the second lower surface 104c of the mounting base 104 and the upper surface 110a of the showerhead 110, the vertical distance h1 between the first lower surface 104b and the second lower surface 104c is made smaller than the thickness h2 of the thermal pad 106 during the process of supporting the base 104. When the screw 402 is tightened, the thermal pad 106 compresses and the first lower surface 104b of the mounting base and the upper surface 110a of the showerhead may move closer together, but due to manufacturing tolerances, the two surfaces do not fit completely together, thereby forming a gap defined by the first lower surface 104b of the mounting base and the upper surface 110a of the showerhead 110.

The showerhead assembly 400 may be constantly switched between different temperatures for process requirements or machine maintenance, and temperature regulation may be achieved by the interaction of the cooling conduits 112 and the heating elements 114. Since the material of the mounting base 104 is an aluminum alloy, and the material of the gas shower head 110 is single crystal silicon or silicon carbide, the coefficient of thermal expansion of the aluminum alloy is between 1.881 × 10 e-5/deg.C and 2.360 × 10 e-5/deg.C, and the coefficient of thermal expansion of the single crystal silicon or silicon carbide is 2.5 × 10 e-6/deg.C, the difference in the thermal expansion systems is close to one order of magnitude. Therefore, with the frequent temperature changes, a significant relative displacement between the showerhead 110 and the mounting base 104 occurs, and the thermal pad has a thermal expansion coefficient of 2.5 × 10 e-5/deg.c, which is close to that of aluminum alloy, so that the lower surface 106b of the thermal pad 106 and the upper surface 110a of the showerhead generate significant friction, and particles may be generated and accumulated in the gap formed between the first lower surface 104b of the mounting base and the upper surface 110a of the showerhead 110. As the process gas flows through the gas path 410, particles are blown out of the gaps and through the gas injection holes 416, and eventually drift with the gas flow to the wafer surface or fall into the plasma environment of the chamber, thereby causing particle contamination to the wafer, impairing the quality of the plasma etched wafer, and affecting the processing rate. In addition, the thermal pad 106 is exposed to an ambient temperature of up to 260 degrees, so the thermal pad 106 is required to be resistant to high temperature. Meanwhile, in order to facilitate the disassembly and maintenance of the gas shower head 110, the thermal pad 106 is required to have the characteristic of no viscosity after passing through a high-temperature environment.

For the above reasons, the present invention provides a laminated thermal pad 106, as shown in fig. 2 and 3, the thermal pad 106 of the present invention is composed of a first Teflon material layer 608, a first thermal conductive layer 604, a thermal conductive support layer 602, a second thermal conductive layer 606, and a second Teflon material layer 610, which are sequentially laminated. The thermally conductive support layer 602 is composed of a hard material comprising one or more of gold, silver, aluminum, or stainless steel, and in this embodiment is composed of aluminum. A first heat conducting layer 604 and a second heat conducting layer 606 are respectively disposed on the upper and lower surfaces of the heat conducting supporting layer 602, and the first and second

heat conducting layers

604 and 606 include one or two of graphite and heat conducting silica gel, and in this embodiment, are composed of a mixture of graphite and heat conducting silica gel. First and

second layers

608 and 610 of Teflon material are disposed on the surfaces of the first and second thermally

conductive layers

604 and 606, respectively. Further, the first and second layers of Teflon

material

608 and 610 include one or more of PTFE, FEP, PFA, or ETFE. Since the high temperature of the plasma of the showerhead assembly 400 during operation is conducted to the showerhead 110, through the thermal pad 106, further to the support assembly 104, and through the cooling conduit 112 mounted in the support assembly 104, there is a high temperature requirement for the thermal pad 106, and the first and second Teflon material layers 608 and 610 of the thermal pad 106 of the present invention can withstand operating temperatures between 150 c and 260 c. Because the thermal pad 106 must have good thermal conductivity and the Teflon material layers are not good conductors of heat, the thickness of the first and second Teflon material layers 608 and 610 is required to affect the heat conduction of the thermal pad 106 if it is too thick and to affect the strength of the first and second Teflon material layers 608 and 610 if it is too thin. Tests show that the thickness of the first and second Teflon material layers 608 and 610 is between 5 micrometers and 70 micrometers, which is good for both good thermal conductivity and strength of the high temperature resistant plastic layer. And at the same time, the conduction of a Radio Frequency (RF) signal loop is not influenced. Because first and second

Teflon material layer

608 and 610 have high temperature resistant, wear-resisting and inviscid's characteristics, consequently when heat conduction pad 106 takes place the friction with mounting base 104 and gas shower head 110, can obviously reduce the production of granule to avoid producing particle pollution to the wafer, when changing gas shower head 110, conveniently disassemble gas shower head 110 from mounting base 104 simultaneously.

The manufacturing method of the heat conducting pad 106 comprises the following steps of respectively arranging a first heat conducting layer 604 and a second heat conducting layer 606 on the upper surface and the lower surface of a heat conducting support layer 602, coating a Teflon material solution on the surfaces of the first heat conducting layer 604 and the second heat conducting layer 606 and solidifying, wherein the composition of the Teflon material solution can be one or more than two of PTFE, FEP, PFA or ETFE, repeating the coating and solidifying steps to form a first Teflon material layer 608 and a second Teflon material layer 610, and the material compositions of the first Teflon material layer 608 and the second Teflon material layer 610 can be the same or different, and the thickness of the first Teflon material layer 608 and the second Teflon material layer 610 can be controlled to be between 5 micrometers and 70 micrometers.

In another embodiment, as shown in fig. 4, the thermal pad 700 is fabricated by disposing a first thermal conductive layer 604 and a second thermal conductive layer 606 on the upper and lower surfaces of a thermal conductive support layer 602, respectively, applying a Teflon material solution, which may be one or more of PTFE, FEP, PFA, or ETFE, on the surfaces of the first and second thermal conductive layers 604 and 606 and on the sides of the thermal conductive support layer 602 and the first and second thermal conductive layers 604 and 606, and curing, repeatedly applying and curing, forming first and second Teflon material layers 608 and 610 on the surfaces of the first and second thermal conductive layers 604 and 606, forming a third Teflon material layer 702 on the sides of the first and second Teflon material layers 608 and 610, the first and second thermal conductive layers 604 and 606, and the thermal conductive support layer 602, the first Teflon material layer 608, the second Teflon material layer 610, and the third Teflon material layer 702 may have the same material composition, alternatively, the thickness of the first, second and third layers of Teflon material 608, 610 and 702 are controlled to be between 5 microns and 70 microns, and finally, the first, second and third layers of Teflon material 608, 610 and 702 together form the outer surface of the thermal pad 700. This embodiment has an advantage in that the wear resistance of the side wall of the thermal pad can be further improved, reducing the generation of particles.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be limited only by the attached claims.

Claims

1. A gas showerhead assembly, comprising: the device comprises a mounting base, a heat conducting pad, a grounding ring and a gas spray head; a heat conducting pad is arranged between the grounding ring and the mounting base, and the three parts are fixed together; a heat conducting pad is arranged between the gas spray head and the mounting base, and the three parts are fixed together; the method is characterized in that: the first lower surface of the mounting base is lower than the second lower surface in the vertical direction, and the upper surface of the thermal pad is in contact with the second lower surface of the mounting base, the thermal pad including: the first Teflon material layer, the first heat-conducting layer, the heat-conducting supporting layer, the second heat-conducting layer and the second Teflon material layer are sequentially stacked, and the first heat-conducting layer and the second heat-conducting layer comprise one type of heat-conducting silica gel.

2. A gas showerhead assembly according to claim 1, wherein: the heat-conducting supporting layer is made of a hard material.

3. A gas showerhead assembly according to claim 2, wherein: the hard material comprises one or more than two of gold, silver, aluminum or stainless steel.

4. A gas showerhead assembly according to claim 1, wherein: the first and second thermally conductive layers comprise a mixture of graphite and thermally conductive silica gel.

5. A gas showerhead assembly according to claim 1, wherein: and the side surfaces of the first and second Teflon material layers, the first and second heat conduction layers and the heat conduction support layer are provided with a third Teflon material layer.

6. A gas showerhead assembly according to claim 1, wherein: the first Teflon material layer comprises one or a mixture of more than two of PTFE, FEP, PFA or ETFE.

7. A gas showerhead assembly according to claim 1, wherein: the second Teflon material layer comprises one or more than two of PTFE, FEP, PFA or ETFE.

8. A gas showerhead assembly according to claim 5, wherein: the third Teflon material layer comprises one or more than two of PTFE, FEP, PFA or ETFE.

9. A gas showerhead assembly according to claim 1, wherein: the first and second layers of teflon material withstand temperatures between 150 degrees celsius and 260 degrees celsius.

10. A gas showerhead assembly according to claim 5, wherein: the third layer of teflon material withstands temperatures between 150 degrees celsius and 260 degrees celsius.

11. A gas showerhead assembly according to claim 1, wherein: the first and second layers of teflon material have a thickness between 5 and 70 microns.

12. A gas showerhead assembly according to claim 5, wherein: the thickness of the third teflon material layer is between 5 microns and 70 microns.

13. A plasma processing apparatus comprising a gas shower head assembly, characterized by: the gas shower head assembly as claimed in any one of claims 1 to 12 for use in a plasma processing apparatus.

14. A method of making a gas showerhead assembly comprising the steps of providing a mounting base, providing a thermal pad between the mounting base and a ground ring and between the mounting base and a gas showerhead, the mounting base having a first lower surface vertically lower than a second lower surface, contacting an upper surface of the thermal pad with the second lower surface of the mounting base, the method comprising: the upper surface and the lower surface of the heat conduction supporting layer are respectively provided with a first heat conduction layer and a second heat conduction layer, Teflon material solution is smeared on the surfaces of the first heat conduction layer and the second heat conduction layer and is cured, and the steps of smearing and curing are repeated to form a first Teflon material layer and a second Teflon material layer with appointed thickness, wherein the first heat conduction layer and the second heat conduction layer comprise graphite or heat conduction silica gel.

15. A method of making a gas showerhead assembly as defined in claim 14 wherein: and coating a Teflon material solution on the side surfaces of the first Teflon material layer, the second Teflon material layer, the first heat conduction layer, the second heat conduction layer and the heat conduction support layer, curing, and repeating the coating and curing steps to form a third Teflon material layer with a specified thickness.

16. The method of claim 14, wherein the step of forming a showerhead assembly further comprises the steps of: placing a heat conducting pad between the grounding ring and the mounting base, and fixing the three parts together through a connecting device; the heat conducting pad is arranged between the gas spray head and the mounting base, and the three components are fixed together through the connecting device.