JP7077072B2 - Plasma processing equipment and plasma processing method - Google Patents

Description

The present invention relates to a plasma processing apparatus that processes an object using microwave plasma, and a plasma processing method.

The above-mentioned plasma processing apparatus irradiates a gas with microwaves output from a microwave source to generate microwave plasma, and supplies radicals contained in the microwave plasma mainly to a processing target. The plasma processing apparatus includes a generation space for generating microwave plasma and a processing space for accommodating a processing target in communication with the generation space. The generation space is partitioned by a microwave transmission window that transmits microwaves, and the output port of the waveguide is connected to the microwave transmission window. Then, the plasma processing device supplies gas to the generation space, and also transmits the microwave propagating through the waveguide into the generation space through the microwave transmission window to generate microwave plasma in the generation space (). For example, see Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-29559

By the way, the chamber wall for partitioning the generation space includes an opening opened toward the output port of the waveguide, an annular fitting groove surrounding the opening, and a sealing member fitted in the fitting groove. The microwave transmission window is pressed against the sealing member to close the opening from outside the chamber wall. On the other hand, the gas supplied to the generation space may stay in a slight gap between the chamber wall and the microwave transmission window to generate microwave plasma. In particular, the gap between the fitting groove and the microwave transmission window is larger than that of other parts by the depth of the groove, and it is easy to generate microwave plasma. As a result, some of the sealing members continue to be exposed to microwave plasma, leading to the formation of cracks and the progress of hardening. In the above-mentioned field of plasma processing, the output of microwaves is steadily increasing in order to improve the efficiency of processing, so that suppression of deterioration in the sealing member has become a more serious problem.

An object of the present invention is to provide a plasma processing apparatus capable of suppressing deterioration of a sealing member interposed between a chamber wall and a microwave transmission window, and a plasma processing method.

A plasma processing device for solving the above problems is provided between a chamber wall provided with a fitting groove and grounded, a microwave transmission window facing the chamber wall, and the chamber wall and the microwave transmission window. It is provided with an intervening seal member. The sealing member is fitted in the fitting groove to partition the gap between the chamber wall and the microwave transmission window into a generation space and an external space. The fitting groove includes a first groove side surface on the generation space side and a second groove side surface on the external space side, and the first groove side surface has an inclination with respect to the groove depth direction, and the microwave is used. A portion closer to the transmission window has a shape that is farther from the generation space, and a sealing portion that comes into contact with the sealing member is provided between the groove bottom and the groove opening. The distance between the groove opening and the sealing portion is less than the sheath length of the plasma generated in the generation space.

A plasma processing method for solving the above problems includes a sealing member interposed between a chamber wall provided with a fitting groove and grounded, and a microwave transmission window facing the chamber wall, and the sealing member comprises a sealing member. It is a plasma processing method using a plasma processing apparatus that is fitted in the fitting groove and divides a gap between the chamber wall and the microwave transmission window into a generation space and an external space. The fitting groove includes a first groove side surface on the generation space side and a second groove side surface on the external space side, and the first groove side surface has an inclination with respect to the groove depth direction, and the microwave is used. A portion closer to the transmission window has a shape that is farther from the generation space, and a sealing portion that comes into contact with the sealing member is provided between the groove bottom and the groove opening. Then, gas is supplied to the generation space so that the distance between the groove opening and the sealing portion is less than the sheath length in the generation space, and microwaves are supplied from the microwave transmission window to the generation space. Propagate.

The region facing the above-mentioned microwave transmission window is a region to be irradiated with microwaves transmitted through the microwave transmission window. The chamber wall is located in the region facing the microwave transmission window and forms a slight gap with the microwave transmission window. The distance between the fitting groove and the microwave transmission window is larger than that of other parts in the gap between the chamber wall and the microwave transmission window by the depth of the fitting groove. In this respect, in each of the above-described configurations, the distance between the groove opening and the sealing portion is less than the sheath length in the generation space, so that there is sufficient space between the groove opening and the sealing portion to form a sheath. Is hard to exist. Therefore, it is possible to suppress the generation of microwave plasma in the fitting groove. As a result, deterioration of the sealing member interposed between the chamber wall and the microwave transmission window can be suppressed.

The plasma processing apparatus further includes a waveguide that guides microwaves to the microwave transmission window along the traveling direction. The microwave transmission window extends in a plane including the traveling direction, and the chamber wall is connected to the fitting groove and has a depth equal to or higher than the groove depth of the fitting groove, and the above-mentioned Further provided with a circular hole having a diameter of the same size as the groove width of the fitting groove. When viewed from the direction facing the microwave transmission window, the straight line extending in the traveling direction through the center of the microwave transmission window is the center line, and the circular hole is located outside the center line. You may.

A plasma processing device for solving the above problems is provided between a chamber wall provided with a fitting groove and grounded, a microwave transmission window facing the chamber wall, and the chamber wall and the microwave transmission window. It includes an intervening seal member and a waveguide that guides microwaves to the microwave transmission window along the traveling direction. The sealing member is fitted in the fitting groove to partition the gap between the chamber wall and the microwave transmission window into a generation space and an external space, and the microwave transmission window is a plane including the traveling direction. The chamber wall is connected to the fitting groove, has a depth equal to or larger than the groove depth of the fitting groove, and has a circular hole having a groove width of the fitting groove as a diameter. Further prepare. When viewed from the direction facing the microwave transmission window, the straight line extending in the traveling direction through the center of the microwave transmission window is the center line, and the circular hole is located outside the center line. do.

In the plasma processing apparatus, the range in which the central angle around the center with respect to the center line is −60 ° or more and 60 ° or less is the high irradiation region, and the circular hole is formed in a region other than the high irradiation region. It may be located.

In the method for forming the fitting groove described above, for example, the chamber wall is machined by using a drill whose diameter is increased toward the tip so as to form a dovetail groove. At this time, a circular hole formed by the tip of the drill is formed in the chamber wall prior to the formation of the fitting groove, and then the fitting groove is formed so as to extend radially from the inner peripheral surface of the circular hole. It begins to be done. As a result, the above-mentioned circular hole is connected to the fitting groove and has a depth equal to or higher than the groove depth of the fitting groove and has a groove width of the fitting groove as a diameter.

Here, the inner peripheral surface of the circular hole does not have the above-mentioned first groove side surface, and it is difficult to come into contact with the sealing member. The portion of the circular hole that comes into contact with the seal member is not the inner peripheral surface of the circular hole but the bottom of the groove. As a result, the distance between the portion in contact with the seal member and the groove opening may be greater than or equal to the sheath length of the plasma generated in the generated space in the circular hole. In this respect, in each of the above-mentioned configurations, the circular holes are arranged so as to avoid the region where the microwave irradiation is relatively high. Therefore, deterioration of the sealing member due to the presence of the circular hole can be suppressed.

In the plasma processing apparatus, the fitting groove may be a dovetail groove. According to this configuration, deterioration of the seal member can be suppressed, and the seal member fitted in the fitting groove can be suppressed from coming off the fitting groove.

In the plasma processing apparatus, the side surface of the second groove may extend in the groove depth direction. According to this configuration, it is possible to reduce the fitting load of the sealing member on the fitting groove, suppress the sealing member fitted in the fitting groove from coming off from the fitting groove, and achieve a balance between them. Become.

The apparatus diagram which shows the apparatus configuration of one Embodiment of a plasma processing apparatus. The cross-sectional view which shows the 1st example of the seal structure in one Embodiment. The cross-sectional view which shows the 2nd example of the seal structure in one Embodiment. The plan view which shows the arrangement of the circular hole in one Embodiment.

An embodiment of a plasma processing apparatus and a plasma processing method will be described.
[Plasma processing equipment]
As shown in FIG. 1, the plasma processing apparatus includes a chamber 11, a partition member 13, a diffusion member 14, and a seal member 20. Further, the plasma processing apparatus includes a microwave transmission window 21, a waveguide 22, and a microwave source 23.

The chamber 11 has, for example, an aluminum box shape and partitions the processing space 11S. The chamber 11 is grounded and includes an upper wall of the chamber 11 as an example of the chamber wall. The upper wall of the chamber 11 includes a partition hole 12 that penetrates upward.

The partition hole 12 is a hole for partitioning the generation space 20S above the processing space 11S. The partition hole 12 has, for example, a two-stage circular hole shape whose diameter is reduced upward. The partition hole 12 communicates with the gas port 11H.

The gas port 11H is a passage for gas G for generating microwave plasma. The gas G supplied from the gas port 11H is at least one selected from the group consisting of, for example, an oxidizing gas such as oxygen and ozone, a nitride gas such as nitrogen and ammonia, and a rare gas such as helium and argon.

The partition member 13 is a member for partitioning the generation space 20S in the partition hole 12. The partition member 13 has, for example, a two-stage disc shape made of aluminum whose diameter is reduced upward. The partition member 13 includes an outer surface that follows the inner surface of the partition hole 12.

The small diameter portion of the partition member 13 is connected to the small diameter portion of the partition hole 12. The upper end surface of the partition member 13 is located below the upper end of the partition hole 12, and partitions the lower end of the generation space 20S. The large diameter portion of the partition member 13 faces the outlet of the gas port 11H.

The large diameter portion of the partition member 13 guides the gas G coming out of the gas port 11H into the small diameter portion of the partition member 13. The small diameter portion of the partition member 13 is provided with a hole opened in the upper end surface of the partition member 13, and the gas G guided to the small diameter portion of the partition member 13 is above the upper end surface of the partition member 13 (generation space 20S). Derived towards.

The microwave transmission window 21 is a member for partitioning the generation space 20S in the partition hole 12. The microwave transmission window 21 is a member that transmits microwaves, and has, for example, a disk shape made of quartz or aluminum oxide.

The microwave transmission window 21 has a larger diameter than the small diameter portion of the partition hole 12. The microwave transmission window 21 is located directly above the partition hole 12 and partitions the upper end of the generation space 20S. The lower surface of the microwave transmission window 21 and the upper end surface of the partition member 13 sandwich the upper end portion of the partition hole 12 in the vertical direction, thereby partitioning the generation space 20S in the partition hole 12. The generation space 20S is surrounded by the inner surface of the partition hole 12, the upper end surface of the partition member 13, and the lower surface of the microwave transmission window 21.

The partition member 13 includes a lead-out hole 13H at the center of the partition member 13. The lead-out hole 13H communicates the processing space 11S and the generation space 20S. The diffusion member 14 is connected to the lower surface of the partition member 13 via a leg and faces the outlet of the outlet hole 13H.
The diffusion member 14 receives the plasma derived from the outlet hole 13H and diffuses the plasma throughout the processing space 11S.

The waveguide 22 propagates the microwave output from the microwave source 23 to the waveguide space 22S partitioned by the waveguide 22. The microwave transmission window 21 is connected to the output port of the waveguide 22. The size of the output port of the waveguide 22 is wider than the small diameter portion (generation space 20S) of the partition hole 12 when viewed from the direction facing the microwave transmission window 21.

The waveguide 22 propagates the microwave output from the microwave source 23 in the traveling direction, and propagates the microwave to almost the entire microwave transmission window 21. The microwave transmission window 21 extends in a plane including the traveling direction of the microwave (direction from the left to the right of the paper). The frequency of the microwave output by the microwave source 23 is 860 MHz, 2.45 GHz, 8.35 GHz, 5.8 GHz, 1.98 GHz or the like.

The plasma processing apparatus propagates the microwave output to the microwave source 23 to the generation space 20S through the microwave transmission window 21. The microwave propagating in the generation space 20S generates plasma without electrodes in the generation space 20S. At this time, the control unit of the plasma processing apparatus adjusts the flow rate of the gas G supplied to the generation space 20S and the microwave power output to the microwave source ²³ to adjust the plasma density in the generation space 20S to 109 cm. ³ or more and 10 ¹¹ cm ³ or less. Further, the plasma processing apparatus has a sheath length of 0.8 mm or more and 1.0 mm or less in the plasma generated in the generation space 20S. The microwave plasma generated in the generation space 20S is supplied to the processing space 11S while being diffused by the diffusion member 14 through the lead-out hole 13H.

[Seal structure]
FIG. 2 shows an example of a sealing structure between the upper wall of the chamber 11 and the microwave transmission window 21, and FIG. 3 shows another example of the sealing structure. In addition, in FIGS. 2 and 3, for convenience of explaining the gap between the upper wall of the chamber 11 and the microwave transmission window 21 and the stay of the gas G in the gap, the upper wall of the chamber 11 and the microwave are used. The size of the gap with the transmission window 21 is exaggerated.

As shown in FIG. 2, in the first example of the sealing structure, the upper wall of the chamber 11 includes a fitting groove 11G. The fitting groove 11G is an annular groove extending over the entire circumference of the microwave transmission window 21. The sealing member 20 is an O-ring made of an insulating resin such as fluororubber or silicone rubber.

The seal member 20 is fitted in the fitting groove 11G, and divides the gap between the upper wall of the chamber 11 and the microwave transmission window 21 into the generation space 20S and the external space (atmospheric space). The seal member 20 suppresses the gas G supplied to the generation space 20S from leaking into the atmospheric space.

The fitting groove 11G is a dovetail groove provided with two groove side surfaces 11G1 and 11G2. The two groove side surfaces are composed of a first groove side surface 11G1 on the generation space 20S side and a second groove side surface 11G2 on the external space side. The distance between the first groove side surface 11G1 and the second groove side surface 11G2 gradually decreases from the groove bottom toward the groove opening.

The first groove side surface 11G1 has an inclination of, for example, 25 ° with respect to the groove depth direction, and the portion closer to the microwave transmission window 21 has a shape farther from the generation space 20S. Further, the first groove side surface 11G1 is provided with a seal portion P in contact with the seal member 20 in the middle of the groove depth direction. The distance H between the groove opening and the sealing portion P is less than the sheath length of the plasma generated in the generation space 20S.

The second groove side surface 11G2 has an inclination of, for example, 25 ° with respect to the groove depth direction, and the portion closer to the microwave transmission window 21 has a shape closer to the generation space 20S. The second groove side surface 11G2 also has a sealing portion in contact with the sealing member 20 in the middle of the groove depth direction. That is, the seal member 20 is separated from the groove opening of the fitting groove 11G.

The upper wall of the chamber 11 is located in a region facing the microwave transmission window 21, and forms a slight gap between the chamber 11 and the microwave transmission window 21 due to the sealing member 20. The distance between the fitting groove 11G and the microwave transmission window 21 is larger than that of other parts in the gap between the upper wall of the chamber 11 and the microwave transmission window 21 by the depth of the fitting groove 11G. big. These regions facing the microwave transmission window 21 are regions that are irradiated with the microwave transmitted through the microwave transmission window 21.

Here, since the distance H between the groove opening and the seal portion P is less than the sheath length in the generation space 20S, it is difficult for a space sufficient for forming the sheath to exist between the groove opening and the seal portion P. .. Therefore, even if the microwave is irradiated toward the fitting groove 11G, it is possible to suppress the generation of microwave plasma in the fitting groove 11G. As a result, deterioration of the seal member 20 can be suppressed.

As shown in FIG. 3, in the second example of the sealing structure, the upper wall of the chamber 11 includes a fitting groove 11G. The fitting groove 11G is an annular groove extending over the entire circumference of the microwave transmission window 21. Similar to the first example, the first groove side surface 11G1 of the fitting groove 11G has an inclination with respect to the groove depth direction, and the portion closer to the microwave transmission window 21 has a shape farther from the generation space 20S. Also, on the first groove side surface 11G1, the distance H between the groove opening and the sealing portion P is less than the sheath length of the plasma generated in the generation space 20S.

The second groove side surface 11G2 extends in the groove depth direction (vertical direction) and is substantially orthogonal to the upper end surface of the upper wall of the chamber 11 and the lower end surface of the microwave transmission window 21. The groove opening of the fitting groove 11G is narrower than the width (groove width) of the groove bottom portion, and the distance between the first groove side surface 11G1 and the second groove side surface 11G2 gradually decreases from the groove bottom portion toward the groove opening. The second groove side surface 11G2 is separated from the seal member 20 and forms a gap between the second groove side surface 11G2 and the seal member 20.

Again, since the distance H between the groove opening and the seal portion P is less than the sheath length in the generation space 20S, it is difficult for a space sufficient to form the sheath to exist between the groove opening and the seal portion P. .. Therefore, it is possible to suppress the generation of microwave plasma in the fitting groove 11G, and it is possible to suppress the deterioration of the seal member 20.

[Fit groove]
As shown in FIG. 4, the waveguide 22 which is an example of the waveguide is a microwave wave from the microwave source 23 to the microwave transmission window 21 along one direction (traveling direction) toward the microwave transmission window 21. To guide. The microwave transmission window 21 extends in a plane including the traveling direction.

When viewed from the direction facing the microwave transmission window 21, the straight line extending in the traveling direction through the center C of the microwave transmission window 21 is the center line. The range in which the central angle θ around the center C with respect to the center line is −60 ° or more and 60 ° or less is a high irradiation region where the intensity of microwave irradiation is higher than that of other parts.

The upper wall of the chamber 11 comprises a circular hole 11G3 connected to the fitting groove 11G. The circular hole 11G3 has a depth equal to or greater than the groove depth of the fitting groove 11G, and has a diameter having the same size as the width (groove width) of the groove bottom portion of the fitting groove 11G. In FIG. 4, the groove opening of the fitting groove 11G is shown by a thick solid line, and the groove width of the fitting groove 11G has the same size as the diameter of the circular hole 11G3. The circular hole 11G3 is located outside the center line. The circular hole 11G3 is preferably located outside the high irradiation region.

In order to form the fitting groove 11G of the first example, for example, the upper wall of the chamber 11 is machined by using a drill whose diameter is expanded toward the tip. At this time, a circular hole 11G3 is first formed on the upper wall of the chamber 11 by cutting with the tip of the drill, and then the drill moves from the circular hole 11G3 so as to draw a fitting groove 11G, thereby drawing a fitting groove 11G. , The fitting groove 11G is formed.

It is difficult to form a portion of the inner peripheral surface of the circular hole 11G3 that comes into contact with the seal member 20, and the portion of the circular hole 11G3 that comes into contact with the seal member 20 is the groove bottom portion of the circular hole 11G3. As a result, in the circular hole 11G3, the distance between the portion in contact with the seal member 20 and the groove opening may be longer than the sheath length of the plasma generated in the generation space 20S. That is, microwave plasma is more likely to be generated in the circular hole 11G3 than in the fitting groove 11G.

In this respect, if the circular hole 11G3 is located outside the center line, and in particular, if the configuration is located outside the high irradiation region, the circular hole 11G3 is arranged while avoiding the region where the microwave irradiation is relatively high. Therefore, deterioration of the sealing member 20 due to the presence of the circular hole 11G3 can be suppressed.

As described above, according to the above embodiment, the effects listed below can be obtained.
(1) Since the distance between the groove opening and the seal portion P is less than the sheath length in the generation space 20S, it is difficult for a space sufficient for forming the sheath to exist between the groove opening and the seal portion P. Therefore, it is possible to suppress the generation of microwave plasma in the fitting groove 11G. As a result, deterioration of the seal member 20 interposed between the chamber 11 and the microwave transmission window 21 can be suppressed.

(2) The circular hole 11G3 not provided with the first groove side surface 11G1 is arranged so as to avoid a region where microwave irradiation is relatively high. Therefore, deterioration of the sealing member 20 due to the presence of the circular hole 11G3 can be suppressed.

(3) When the fitting groove 11G is a dovetail groove provided with the first groove side surface 11G1, deterioration of the sealing member 20 is suppressed, and the sealing member 20 fitted in the fitting groove 11G is the fitting groove. It is possible to suppress deviation from 11G.

(4) When the second groove side surface 11G2 of the fitting groove 11G extends in the groove depth direction, the fitting load of the sealing member 20 on the fitting groove 11G should be reduced, and the sealing member fitted in the fitting groove 11G should be reduced. It is also possible to prevent the 20 from coming off the fitting groove 11G and to balance these.

The above embodiment can be appropriately modified and implemented as follows.
-In the first example of the seal structure, it is also possible to further provide a backup ring in close contact with the second groove side surface 11G2 between the second groove side surface 11G2 of the fitting groove 11G and the seal member 20.
-The plasma processing device may further include a slot antenna having conductivity on the side opposite to the generation space 20S with respect to the microwave transmission window 21.

θ ... central angle, C ... center, H ... distance, P ... seal location, 11 ... chamber, 11G ... fitting groove, 11G1 ... first groove side surface, 11G2 ... second groove side surface, 11G3 ... circular hole, 11H ... gas Port, 11S ... processing space, 12 ... partition hole, 13 ... partition member, 13H ... lead hole, 14 ... diffusion member, 20 ... seal member, 20S ... generation space, 21 ... microwave transmission window, 22 ... waveguide, 22S ... Waveguide space, 23 ... Microwave source.

Claims (6)

A grounded chamber wall with a fitting groove,
A microwave transmission window facing the chamber wall,
A sealing member interposed between the chamber wall and the microwave transmission window is provided.
The sealing member is fitted in the fitting groove to partition the gap between the chamber wall and the microwave transmission window into a generation space and an external space.
The fitting groove includes a first groove side surface on the generation space side and a second groove side surface on the external space side.
The side surface of the first groove has an inclination with respect to the depth direction of the groove, has a shape in which a portion closer to the microwave transmission window is separated from the generation space, and the seal is provided between the bottom of the groove and the opening of the groove. Equipped with a sealing point that comes into contact with the member,
The distance between the groove opening and the sealing portion is less than the sheath length of the plasma generated in the generation space .
Further provided with a waveguide that guides microwaves along the traveling direction to the microwave transmission window.
The microwave transmission window spreads in a plane including the traveling direction,
The chamber wall has a circular hole and has a circular hole.
The circular hole is
The fitting has a circular hole opening that partially overlaps the groove opening when viewed from a direction facing the microwave transmission window, and the hole opening and the upper end of the side surface of the first groove are connected to each other. It is connected to the groove and extends along the depth direction of the fitting groove so that the fitting groove is connected to the inner peripheral surface of the circular hole, and is deeper than the groove depth of the fitting groove. And has a diameter of the same size as the groove width at the groove bottom of the fitting groove.
When viewed from the direction facing the microwave transmission window, the straight line extending in the traveling direction through the center of the microwave transmission window is the center line, and the circular hole is located outside the center line. To do
Plasma processing equipment. The plasma processing apparatus according to claim 1 , wherein the fitting groove is a dovetail groove. The plasma processing apparatus according to claim 1 , wherein the side surface of the second groove extends in the depth direction of the groove. A grounded chamber wall with a fitting groove,
A microwave transmission window facing the chamber wall,
A sealing member interposed between the chamber wall and the microwave transmission window,
A waveguide that guides microwaves to the microwave transmission window along the traveling direction is provided.
The sealing member is fitted in the fitting groove to partition the gap between the chamber wall and the microwave transmission window into a generation space and an external space.
The fitting groove includes a first groove side surface on the generation space side and a second groove side surface on the external space side.
The microwave transmission window spreads in a plane including the traveling direction,
The chamber wall has a circular hole and has a circular hole.
The circular hole is
When viewed from the direction facing the microwave transmission window, it has a circular hole opening that partially overlaps the groove opening of the fitting groove, and the hole opening and the upper end of the side surface of the first groove are connected to each other. The fitting groove is connected to the fitting groove and extends along the depth direction of the fitting groove so that the fitting groove is connected to the inner peripheral surface of the circular hole. It has a depth greater than that and has a diameter of the same size as the groove width of the fitting groove.
When viewed from the direction facing the microwave transmission window, the straight line extending in the traveling direction through the center of the microwave transmission window is the center line, and the circular hole is located outside the center line. Plasma processing equipment. The high irradiation region is a range in which the central angle around the center with respect to the center line is -60 ° or more and 60 ° or less with the traveling direction as 0 ° from the center .
The plasma processing apparatus according to any one of claims 1 to 4 , wherein the circular hole is located outside the high irradiation region. A sealing member is provided between a chamber wall grounded with a fitting groove and a microwave transmission window facing the chamber wall, and the sealing member is fitted into the fitting groove to the chamber wall. It is a plasma processing method using a plasma processing apparatus that divides a gap between the microwave transmission window into a generation space and an external space.
The fitting groove includes a first groove side surface on the generation space side and a second groove side surface on the external space side.
The side surface of the first groove has an inclination with respect to the depth direction of the groove, has a shape in which a portion closer to the microwave transmission window is separated from the generation space, and the seal is provided between the bottom of the groove and the opening of the groove. Equipped with a sealing point that comes into contact with the member,
The plasma processing device is
Further provided with a waveguide that guides microwaves along the traveling direction to the microwave transmission window.
The microwave transmission window spreads in a plane including the traveling direction,
The chamber wall has a circular hole and has a circular hole.
The circular hole is
The fitting has a circular hole opening that partially overlaps the groove opening when viewed from a direction facing the microwave transmission window, and the hole opening and the upper end of the side surface of the first groove are connected to each other. It is connected to the groove and extends along the depth direction of the fitting groove so that the fitting groove is connected to the inner peripheral surface of the circular hole, and is deeper than the groove depth of the fitting groove. And has a diameter of the same size as the groove width at the groove bottom of the fitting groove.
When viewed from the direction facing the microwave transmission window, the straight line extending in the traveling direction through the center of the microwave transmission window is the center line, and the circular hole is located outside the center line.
Gas is supplied to the generation space and microwaves are propagated from the microwave transmission window to the generation space so that the distance between the groove opening and the sealing portion is less than the sheath length in the generation space. Plasma processing method to make.

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