JP3058530B2 - Plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus.

[0002]

2. Description of the Related Art As is well known, active species such as ions, complex ions, and radicals are present in plasma obtained by discharging a certain kind of gas. Surface treatment of a semiconductor wafer; Plasma processing is used in a semiconductor wafer manufacturing process to perform various kinds of film etching, film formation, and the like because, for example, high-precision process control can be performed.

One method of generating plasma is to apply high-frequency power to a processing gas. A plasma processing apparatus using this method, for example, a single wafer type etching apparatus, has a lower electrode and a lower electrode in a processing chamber having an airtight seal structure. An upper electrode forming a gas supply unit is arranged so as to face the same, a high-frequency voltage is applied between the upper electrode and the lower electrode to generate plasma, and the object to be processed placed on the lower electrode For example, it is configured to etch the surface of a semiconductor wafer.

Conventionally, in such a plasma processing apparatus, a coaxial cable has been used as a means for connecting the lower electrode and the high-frequency power supply. However, the connection between the shielded wire and the processing chamber is troublesome, and the method of this connection is difficult. Recently, there is a problem that the impedance of the device changes due to the fact that Teflon used as a dielectric of a coaxial cable for high power is expensive. Sticks are being considered.

FIG. 4 shows a conventional example of an etching apparatus using such a high-frequency power supply rod. An upper electrode 11 also serving as a gas supply unit in a processing chamber 1 and a susceptor 13 supported on a susceptor support 12 are provided. The lower conductor 10 is disposed in opposition to the lower conductor 10, the inner conductor rod 14 of the high-frequency power supply rod projects from the lower side of the processing chamber 1 to the susceptor 13, and the outer conductor tube 15 of the high-frequency power supply rod is Connected to the wall. This bottom wall is connected to the upper electrode 11 via the side wall of the processing chamber 1.
Is electrically connected to

The lower ends of the inner conductor rod 14 and the outer conductor tube 15 are electrically connected to a high-frequency power source E and a ground via a matching circuit MC in a matching box M, respectively. The lower ends of the inner conductor rod 14 and the outer conductor tube 15 and the matching circuit part MC are connected to the power supply rods 14a, 15
a. In FIG. 4, reference numeral 16 denotes an exhaust pipe, 1
Reference numerals 7 and 18 denote insulating portions, reference numeral 19 denotes a coolant reservoir for circulating a cooling medium, and reference numeral W denotes a wafer to be processed.

[0007]

By the way, a pipe for circulating a cooling medium, such as liquid nitrogen, into the coolant reservoir 19 and a back side (not shown) on the back side of the wafer W are provided below the processing chamber 1. There are gas introduction pipes for supplying gas. Therefore, the matching box M is located considerably below the bottom wall of the processing chamber 1, so that the line length of the high-frequency power supply rod is considerably long. When the high-frequency power supply rod is long as described above, the axes of the internal conductor rod 14 and the external conductor pipe 15 become large when the internal conductor rod 14 and the external conductor pipe 15 are attached to the power supply rods 14a and 15a by screws, for example. There was a shift.

On the other hand, recently, the diameter of a wafer has tended to increase from a conventional 6-inch size to an 8-inch size and further to a 12-inch size. In addition, the technology of liquid crystal panels has rapidly progressed and the size thereof has been increased, and apparatuses for performing processes such as film formation and etching on such LCD substrates have been developed.

When plasma processing, for example, etching is performed on an object to be processed such as a wafer or LCD substrate having such a large size, the high-frequency power must be as large as about 4 Kw. Here, the high-frequency power supply rod is
Since the design must be made so as to have a predetermined characteristic impedance, the ratio of the diameter of the inner conductor rod 14 to the diameter of the outer conductor tube 15 is determined based on this characteristic impedance. For this reason, when the high-frequency power is increased, the axes of the inner conductor rod 14 and the outer conductor tube 15 are shifted and approach to each other, and there is a possibility that discharge occurs between the inner conductor rod 14 and the outer conductor tube 15.

When a discharge occurs in the high-frequency power supply rod, the supply efficiency of the high-frequency power is reduced to lower the etching rate, and the plasma becomes unstable, impedance cannot be matched, and stable plasma processing cannot be performed. . Further, the high-frequency power supply rod itself is damaged by the discharge.

The present invention has been made under such circumstances, and an object of the present invention is to provide a plasma processing apparatus capable of reliably preventing discharge inside a high-frequency power supply rod.

[0012]

According to a first aspect of the present invention, a high-frequency power is supplied between a lower electrode and an upper electrode in a processing chamber to convert a processing gas into a plasma, and the plasma causes a process target on the lower electrode to be processed. In the plasma processing apparatus for processing the body, the lower end side is electrically connected to a high-frequency power supply, an internal conductor rod provided from the lower side of the processing chamber to the lower electrode,
Lower end is grounded, and a high-frequency power feed rod become more double pipe structure and an outer conductor tube upper end side connected to the bottom of the processing chamber, the outer
A peripheral surface is on the inner peripheral surface of the outer conductor tube, and an inner peripheral surface is the inner conductor surface.
A ring-shaped fixing member which is provided between the inner conductor bar and the outer conductor tube so as to be in contact with the outer peripheral surface of the body bar, and is made of an insulating material for fixing the mutual positions of the inner conductor bar and the outer conductor tube. characterized by comprising a and.

In this case, the upper surface of the ring-shaped fixing member and
On at least one surface of the lower surface,
It is preferable to form recesses and / or protrusions along
Between the inner conductor rod of the high-frequency power supply rod and the outer conductor tube.
Gas introducing means for introducing a drying gas into the
The space between the inner conductor rod of the power supply rod and the outer conductor tube is, for example, SF6.
It is preferable to use a dry gas atmosphere such as a gas.

[0014]

The fixing member made of an insulating material is formed in a ring shape corresponding to, for example, the outer diameter of the inner conductor rod and the inner diameter of the outer conductor pipe, and is fitted between the inner conductor rod and the outer conductor pipe. The axes of the inner conductor bar and the outer conductor tube coincide, and the distance between the inner conductor bar and the outer conductor tube becomes constant. A concave portion and / or a concave portion is provided on at least one of the upper surface and the lower surface of the fixing member.
Alternatively , when the convex portion is formed, the creepage distance increases, and there is no possibility of discharging along the surface of the fixing member.

Further, if a dry gas atmosphere is provided between the inner conductor rod and the outer conductor tube, for example, even when the lower electrode is cooled by a cooling medium, the inside of the high-frequency power supply rod is less likely to condense and discharge occurs. It becomes difficult. In this case SF
6 High frequency power supply due to high insulation in a gas atmosphere
Discharge in the rod can be more reliably prevented.

[0016]

Embodiments of the present invention will be described below. FIG.
1 is a schematic cross-sectional view showing the overall configuration of a plasma processing apparatus, for example, an etching apparatus according to one embodiment of the present invention. FIG.
It is sectional drawing to which the principal part of this Example was expanded. The processing chamber 2 shown in FIG. 1 is provided with gate valves 21 and 22 for hermetically sealing the space between the processing chamber 2 and a load lock chamber (not shown) on the outer wall. For example, a columnar susceptor support 31 made of a conductive metal is provided.

A susceptor 32 made of a conductive metal such as aluminum is mounted on the susceptor support 31 by, for example, a bolt. In this example, the susceptor support 31 and the susceptor 32 constitute a lower electrode. You. On the upper surface of the susceptor 32, the electrostatic chuck sheet 3
The electrostatic chuck sheet 33 is formed by covering an electrode plate 34 made of, for example, electrolytic foil copper from both sides with an insulating film made of, for example, a polyimide film 35. It is placed on the susceptor 32 via the sheet 33.

A coolant reservoir 41 for circulating a cooling medium is formed inside the susceptor support 31, and the coolant reservoir 41 is provided therein.
1A and a discharge pipe 41B are provided, and a cooling medium, such as liquid nitrogen, supplied into the refrigerant reservoir 41 via the introduction pipe 41A is discharged to the outside of the apparatus via the discharge pipe 41B. A ground member 43 that is continuous with the wall of the processing chamber 2 is provided around the susceptor support base 31 and the susceptor 32 via an insulating part 42.

A matching box 6 is disposed below the processing chamber 1 via a high-frequency power supply rod 5. The high-frequency power supply rod 5 has a double-tube structure in which an inner conductor rod 51 formed of a tubular body and an outer conductor tube 52 are concentrically arranged. It is made of a less conductive material, for example, silver or copper. When copper is used, its surface is plated with silver.
The upper end of the inner conductor rod 51 is joined to the lower surface of the susceptor 32, and the lower end of the inner conductor rod 51 is connected to a power supply rod 53.
And a high-frequency power supply 61 via a matching circuit unit 60 including a blocking capacitor and the like in the matching box 6. In addition, this internal conductor rod 5
A vent hole 51a for venting the dry gas is formed in the tube wall of one as described later.

The upper end of the outer conductor tube 52 is, for example, threaded on the outer peripheral surface thereof and is screwed to the bottom wall (ground member 43) of the processing chamber 2 to be electrically connected thereto. O-ring 50 between 52 and the bottom wall (see FIG. 2)
Is interposed. The lower end of the outer conductor tube 52 is grounded via a feed rod 54 and the matching circuit section 60. An insulating ring 55 is interposed between the insulating portion 42 and the ground member 43 and the inner conductor bar 51, and a lower end surface of the insulating ring 55 closes an upper end portion of the outer conductor tube 52. Inner conductor rod 51 and outer conductor tube 52
And the inner conductor rod 51 is exposed on the exposed surface.
A concave portion 56 (see FIG. 2) is formed in a ring shape so as to surround.

A power supply line 62 is provided through the inner conductor rod 51. The lower side of the power supply line 62 is connected to a DC power supply 63 in the matching box 6 via a switch 64. The upper end is electrically connected to the electrode plate 35 of the electrostatic chuck sheet 33.

Between the inner conductor rod 51 and the outer conductor tube 52, there are two internal positions, for example, near the middle position in the longitudinal direction of the outer conductor tube 52 and above the power supply rod 54 at the lower end. Fixing members 7 and 8 for fixing the mutual positions of the conductor rod 51 and the external conductor tube 52 are provided respectively.
These fixing members 7 and 8 are formed by molding an insulating material such as Teflon into a ring shape so that the outer peripheral surface contacts the inner peripheral surface of the outer conductor tube 52 and the inner peripheral surface contacts the outer peripheral surface of the inner conductor rod 51. It is inserted.

As shown in FIGS. 2 and 3, the upper fixing member 7 has, for example, concave portions 71 on the upper and lower sides near the middle portion between the inner conductor rod 51 and the outer conductor tube 52. The recessed portion 71 has a bottom surface formed with a ventilation hole 72 penetrating the fixing member 7.

The lower fixing member 8 has a recess 81 similarly formed on the upper surface side, and O-rings 82 and 83 interposed between the inner conductor rod 51 and the outer conductor tube 52, respectively. The space above the fixing member 8 is hermetically sealed from the outside.

Each of the outer conductor tubes 52 has a valve V
1, a gas introduction pipe 91 provided with V2 and an exhaust pipe 92 are connected. On the upstream side of the gas introduction pipe 91, a dry gas having a very small amount of moisture, for example, a high insulating property is provided. The SF6 gas supply source is connected and the exhaust pipe 92
The exhaust means 93 is connected to the downstream side of. However, the exhaust unit 93 may also be used as an exhaust unit such as a vacuum pump for evacuating the inside of the processing chamber 2. In this example, the gas introduction pipe 91 and the valve V1 show a part of the gas introduction means.

Further, above the susceptor 32, the processing chamber 2
The upper electrode 23 which is electrically connected to the side wall of the substrate and serves also as a gas supply unit is disposed so as to face the upper electrode 23. A gas supply pipe 24 for supplying a processing gas such as CHF3 or CF4 or an inert gas into the processing chamber 2 is connected to the upper electrode 23, and a processing gas is provided on the lower surface of the upper electrode 24. Is provided in the processing chamber 1 for example in the form of a shower. An exhaust pipe 26 connected to a vacuum pump (not shown) is provided below the processing chamber 2.

Next, the operation of the above embodiment will be described. First, the valve V2 of the exhaust pipe 92 connected to the external conductor pipe 52 is opened in advance, and the external conductor pipe 52 is
Exhaust the inside. As described above, the fixing member 7 has the ventilation hole 72.
Is formed, the space above the fixing member 7 is also exhausted. Further, since the inner conductor rod 51 is formed with the ventilation hole 51a, the inside of the inner conductor rod 51 is also evacuated through the vent hole 51a, and for example, the pressure in the high-frequency power supply rod 5 becomes about 10 -2 Torr.
The pressure is reduced to Subsequently, the valve V2 is closed, and the valve V1 is closed.
To open a dry gas such as SF from a gas supply source (not shown).
6 Gas is introduced into the high-frequency power supply rod 5, the valve V1 is closed, and the inside of the high-frequency power supply rod 5 is filled with, for example, SF of about 2 kgf / cm 2.
6 Create a gas atmosphere.

Then, the semiconductor wafer W to be processed is carried into the processing chamber 2 by a transfer arm (not shown) via the gate valve 21 and, for example, liquid nitrogen is allowed to flow through the cooling reservoir 41 to a predetermined temperature, for example, 0 ° C. The susceptor 32, which has been cooled to -100C, is adsorbed and placed via the electrostatic chuck sheet 33. Then, the processing gas is supplied into the processing chamber 2 through the upper electrode 23 and the gas diffusion plate 25 by the gas supply pipe 24, and the processing chamber 2 is evacuated through the exhaust pipe 26.
The inside of the processing chamber 2 is maintained at a predetermined pressure.

On the other hand, high-frequency power supply 61 → matching circuit section 6
0 → inner conductor rod 51 → susceptor 32 (lower electrode) → upper electrode 23 → wall of processing chamber 2 → outer conductor tube 52 → high-frequency power of, for example, 13.56 MHz, 1 Kw is applied in a loop of grounding and upper electrode 23 Then, plasma is generated between the susceptor 32 and the semiconductor wafer W is etched. The frequency of the high frequency power supply 61 is, for example, 40
MHz may be used. After the plasma processing, the semiconductor wafer W is transferred to the gate valve 22 by a transfer arm (not shown).
Through a load lock chamber (not shown).

According to the above-described embodiment, since the ring-shaped fixing members 7 and 8 are provided at two positions in the length direction between the inner conductor rod 51 and the outer conductor tube 52, the inner conductor rod 51 is provided. Since the axes of the inner conductor rod 52 and the outer conductor tube 52 coincide with each other, the distance between them becomes the same at any position in the longitudinal direction and the local conductors do not abnormally approach each other.
There is no possibility of discharging through the space between the first conductor tube 52 and the outer conductor tube 52. Since ring-shaped concave portions 71 and 81 are formed on both upper and lower surfaces of the fixing members 7 and 8,
8 has a large creepage distance, and therefore there is no danger of discharging along the surfaces of the fixing members 7, 8.

Although the lower electrode 3 is cooled by the cooling medium as described above, the high-frequency power supply rod 5 also has a considerably low temperature. However, since the high-frequency power supply rod 5 is filled with SF6 gas, dew condensation is suppressed. And the SF6 gas has a large insulating property.
Discharge between the first and outer conductor tubes 52 becomes difficult.

In the above description, the number of fixing members in the high-frequency power supply rod 5 may be appropriately determined according to the length of the high-frequency power supply rod 5, and may be, for example, one or three or more. Further, the fixing member may not be formed over the entire circumference, may be formed on a part of the circumference, and may be formed not only with the concave part but also with the convex part in increasing the creepage distance. Both may be formed.

The present invention is not limited to the etching apparatus, but may be any apparatus that supplies power through the high-frequency power supply rod 4 and performs plasma processing on an object to be processed such as a semiconductor wafer or an LCD substrate. The present invention can also be applied to a heat treatment apparatus such as CVD, an ashing apparatus, and the like. In addition, since the high-frequency power supply rod may be dewed by moisture in the atmosphere, the present invention can be applied to a case where the susceptor support has no cooling reservoir. The dry gas may be a gas other than SF6 gas, for example, an inert gas such as nitrogen gas, or air from which moisture has been sufficiently removed.

[0034]

According to the first aspect of the present invention, a fixing member is provided between the inner conductor rod of the high-frequency power supply rod and the outer conductor pipe so that the axes of the inner conductor rod and the outer conductor pipe do not shift. Is
Therefore, discharge inside the high-frequency power supply rod can be prevented,
The effect is that the reduction in power supply efficiency can be suppressed.
is there. According to the second aspect of the present invention, the fixing member has a concave portion and a concave portion.
Large creepage distances due to the formation of
And discharge can be more reliably prevented. The invention of claim 3
According to the present invention, since a dry gas atmosphere is provided between the inner conductor rod and the outer conductor tube, dew condensation in the high-frequency power supply rod can be prevented, and discharge in the high-frequency power supply rod can be more reliably prevented. Since the corrosion of the power supply rod can be suppressed, a decrease in the supply efficiency of the high-frequency power can be suppressed from this point as well. In this case, insulation is provided by using SF6 gas atmosphere.
Discharge in the high-frequency power supply rod
It can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall configuration of an etching apparatus (plasma processing apparatus) according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of an etching apparatus (plasma processing apparatus) according to an embodiment of the present invention.

FIG. 3 is a cutaway perspective view showing a fixing member used in the embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional plasma processing apparatus (etching apparatus).

[Description of Signs] 2 Processing chamber 23 Upper electrode 3 Lower electrode 41 Refrigerant reservoir 5 High-frequency power supply rod 51 Internal conductor rod 52 External conductor pipe 7, 8 Fixing member 61, 71 Recess 91 Gas introduction pipe

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05H 1/46 H01L 21/3065

Claims (4)

(57) [Claims] 1. A plasma processing apparatus for supplying a high-frequency power between a lower electrode and an upper electrode in a processing chamber to convert a processing gas into a plasma and processing an object to be processed on the lower electrode with the plasma, wherein a lower end is provided. A double conductor comprising an internal conductor rod electrically connected to a high-frequency power source and provided from the lower side of the processing chamber to the lower electrode, and an outer conductor pipe grounded at the lower end and connected at the upper end to the bottom of the processing chamber. A high-frequency power supply rod having a tube structure, an outer peripheral surface on the inner peripheral surface of the outer conductor tube, and an inner peripheral surface on the inner conductor surface.
A ring-shaped solid body made of an insulating material is provided between the inner conductor bar and the outer conductor tube so as to be in contact with the outer peripheral surface of the conductor bar, and fixes the mutual position of the inner conductor bar and the outer conductor tube. br /> plasma processing apparatus characterized a constant member, further comprising a. 2. An upper and lower surface of the ring-shaped fixing member.
At least on one side, along the circumferential direction of the high-frequency power supply rod
Claims characterized in that concave portions and / or convex portions are formed.
Item 2. A plasma processing apparatus according to item 1. 3. An internal conductor rod and an external conductor tube of a high-frequency power supply rod.
And a gas introducing means for introducing the dry gas between the
Dry the gap between the inner conductor rod and the outer conductor tube of the high-frequency power supply rod.
3. An atmosphere as defined in claim 1, wherein
Plasma processing equipment. 4. The plasma processing apparatus according to claim 3 , wherein the drying gas is SF6 gas.