CN119170474B - Plasma processing apparatus - Google Patents

Abstract

A plasma processing device comprises: a reaction chamber; a gas shower head, arranged at the top of the reaction chamber; a lower electrode assembly, arranged at the bottom of the reaction chamber, the lower electrode assembly being arranged opposite to the gas shower head; a conductive moving ring, arranged at the periphery of the gas shower head and movable up and down; a grounded plasma confinement ring, arranged at the periphery of the lower electrode assembly; a conductive gasket, arranged between the plasma confinement ring and the moving ring, when the moving ring moves downward to a process position, the moving ring is electrically connected to the plasma confinement ring and grounded through the conductive gasket. The plasma processing device is conducive to reducing the deposition of polymer on the surface of the moving ring.

Description

Plasma processing apparatus

Technical Field

The invention relates to the field of semiconductors, in particular to a plasma processing device.

Background

In a plasma processing apparatus, in order to achieve transfer of a substrate, a wafer transfer port is generally provided on a side wall of a reaction chamber, but the presence of the wafer transfer port makes plasma distribution uniformity in the reaction chamber poor. In order to solve the problem, a moving ring is generally arranged in the reaction cavity, the moving ring can move up and down, when a wafer is required to be transferred, the moving ring is lifted to expose the wafer transfer port, the substrate is transferred through the wafer transfer port, and when the process is required to be processed in the reaction cavity, the moving ring is lowered to a process position, and at the moment, the moving ring covers the wafer transfer port, so that the uniformity of the distribution of plasma above the substrate is improved.

The temperature of the moving ring is typically much lower than the temperature of other parts, and in some processes where large amounts of polymer are produced, the polymer may preferentially deposit on low temperature surfaces, and when such polymers accumulate to a certain level, they may fall off to form particulate contaminants, which may be detrimental to the substrate yield.

Disclosure of Invention

The invention aims to provide a plasma processing device which can reduce the deposition of polymer on the surface of a movable ring and reduce particle pollutants.

The invention provides a plasma processing device which comprises a reaction cavity, a gas spray head, a lower electrode assembly, a conductive moving ring, a grounded plasma limiting ring and a conductive gasket, wherein the gas spray head is arranged at the top of the reaction cavity, the lower electrode assembly is arranged at the bottom in the reaction cavity, the lower electrode assembly is opposite to the gas spray head, the conductive moving ring is arranged at the periphery of the gas spray head and can move up and down, the grounded plasma limiting ring is arranged at the periphery of the lower electrode assembly, and the conductive gasket is arranged between the plasma limiting ring and the moving ring, and when the moving ring moves downwards to a process position, the moving ring is electrically connected with the plasma limiting ring through the conductive gasket to be grounded.

Optionally, the conductive pad is at least one of a metal material or a semiconductor material.

Optionally, when the conductive pad is a metal material, the material of the conductive pad includes at least one of copper, beryllium copper, or nickel.

Optionally, the conductive gasket further comprises a metal layer arranged on the surface of the conductive gasket, wherein the material of the metal layer comprises at least one of silver, gold and nickel.

Optionally, the conductive gasket comprises an inner part and a conductive layer wrapped on the surface of the inner part.

Optionally, the material of the inner part is rubber material, and the material of the conductive layer comprises at least one of copper, beryllium copper or nickel.

Optionally, the conductive gasket is disposed at a position of the plasma confinement ring opposite to the moving ring.

Optionally, the conductive gasket is disposed on an upper surface of the plasma confinement ring.

Optionally, the plasma confinement ring is provided with a first recess recessed in an upper surface thereof, the first recess being for placing the conductive pad.

Optionally, the plasma confinement ring comprises a confinement ring body and a second corrosion-resistant coating layer positioned on the surface of the confinement ring body, wherein the confinement ring body is made of a metal material, the confinement ring body is provided with the first groove which is recessed in the upper surface of the confinement ring body, the side wall and the bottom wall of the first groove are not provided with the second corrosion-resistant coating layer, and the surface of the confinement ring body around the first groove is provided with the second corrosion-resistant coating layer.

Optionally, the material of the plasma confinement ring comprises silicon or silicon carbide.

Optionally, the lower surface of the movable ring is a plane, or the movable ring is provided with a second groove sunk in the lower surface of the movable ring, the second groove is opposite to the first groove, and the second groove is used for accommodating the top of the conductive gasket.

Optionally, when the moving ring moves downwards to the process position, the gas spray head, the lower electrode assembly and the moving ring form a plasma environment, and the plasma processing device further comprises a sealing ring, which is arranged on the inner side of the conductive gasket and used for blocking plasma and reducing corrosion of the plasma to the conductive gasket.

Optionally, a third groove recessed in the upper surface of the plasma confinement ring is further formed in the top of the plasma confinement ring, and the third groove is used for accommodating the sealing ring.

Optionally, the conductive pad is disposed on the lower surface of the movable ring, and the movable ring is provided with a fourth groove recessed on the lower surface of the movable ring, where the fourth groove is used for placing the conductive pad.

Optionally, the material of the movable ring comprises silicon or silicon carbide.

Optionally, the movable ring comprises a movable ring body and a first corrosion-resistant coating, wherein the movable ring body is made of a conductor material, the movable ring body is provided with a fourth groove which is concaved in the lower surface of the movable ring body, the side wall and the bottom wall of the fourth groove are not provided with the first corrosion-resistant coating, and the surface of the constraint ring body around the fourth groove is provided with the first corrosion-resistant coating.

Optionally, the plasma confinement ring further comprises a middle grounding ring, wherein the middle grounding ring is arranged below the plasma confinement ring and is grounded, and the plasma confinement ring is electrically connected with the middle grounding ring to be grounded.

Optionally, the reaction chamber further comprises an upper grounding ring which is arranged on the periphery of the gas spray header and positioned between the gas spray header and the movable ring, wherein the upper grounding ring is grounded, and the chamber wall of the reaction chamber is grounded.

Compared with the prior art, the technical scheme of the invention has at least the following beneficial effects:

In the plasma processing device provided by the invention, the movable ring is electrically connected with the plasma confinement ring through the conductive gasket to be grounded only when the movable ring is lowered to the process position, and in addition, the movable ring is not grounded, so that a metal connecting piece is not required to be additionally arranged to realize the grounding of the movable ring, and the movable ring is not influenced by the metal connecting piece in the up-and-down movement process. When the movable ring is lowered to the process position, the movable ring is grounded, so that the plasma bombards the movable ring more severely, the temperature of the movable ring is higher, and therefore, polymers are not easy to deposit on the surface of the movable ring, and the particle pollution is reduced.

Further, the upper grounding ring, the plasma confinement ring and the chamber wall of the reaction chamber are all grounded, and the moving ring is also grounded, so that no potential difference exists between the moving ring and surrounding components, and therefore, arc discharge is not easy to occur between the moving ring and the surrounding components.

Drawings

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

FIG. 2 is a top view of the plasma confinement ring and conductive gasket of FIG. 1;

FIG. 3 is an enlarged partial view of area A of FIG. 1;

FIG. 4 is another partial enlarged view of area A of FIG. 1;

FIG. 5 is a schematic view of a conductive gasket of the present invention;

FIG. 6 is a schematic view of another plasma processing apparatus according to the present invention;

fig. 7 is a top view of the plasma confinement ring and conductive gasket of fig. 6.

Detailed Description

The following describes the technical scheme, the constructional features, the achieved objects and the effects of the embodiments of the present invention in detail with reference to fig. 1 to fig. 7 in the embodiments of the present invention.

It should be noted that, the drawings are in very simplified form and all use non-precise proportions, which are only used for the purpose of conveniently and clearly assisting in describing the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention, so that the present invention has no technical significance, and any modification of structure, change of proportion or adjustment of size, without affecting the efficacy and achievement of the present invention, should still fall within the scope covered by the technical content disclosed by the present invention.

It is noted that in the present invention, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

As described in the background, in existing plasma processing apparatus, the surface of the moving ring is prone to depositing polymer.

In order to solve the technical problem, the invention provides a plasma processing device, wherein a conductive gasket is arranged between a plasma confinement ring and a movable ring, when the movable ring descends to a process position, the movable ring is electrically connected with the plasma confinement ring through the conductive gasket, and the plasma confinement ring is grounded, so that the movable ring is grounded when in the process position, the bombardment of plasma on the surface of the movable ring is enhanced, the temperature of the movable ring is favorably increased, and the deposition of polymer on the surface of the movable ring is reduced.

Fig. 1 is a schematic view of a plasma processing apparatus according to the present invention.

In this embodiment, the plasma processing apparatus 100 is a capacitively coupled plasma etching apparatus, which is a device that generates plasma in a reaction chamber by capacitive coupling from a radio frequency power source applied to a plate and is used for etching. It includes a reaction chamber 101, the reaction chamber 101 includes a substantially cylindrical reaction chamber sidewall made of a metal material, and a wafer transfer port (not shown) is provided on the reaction chamber sidewall for receiving a substrate therein and therein. A gas shower head 102 and a lower electrode assembly 103 opposite to the gas shower head 102 are disposed in the reaction chamber 101, the gas shower head 102 is used for delivering reaction gas into the reaction chamber 101, and meanwhile, is used as an upper electrode of the reaction chamber, and a reaction area is formed between the upper electrode and the lower electrode assembly. At least one radio frequency power supply (not shown in the figure) is applied to one of the upper electrode or the lower electrode assembly through a matching network, a radio frequency electric field is generated between the upper electrode and the lower electrode assembly, the radio frequency electric field is used for dissociating the reaction gas into plasma, the plasma contains a large number of active particles such as electrons, ions, atoms in an excited state, molecules, free radicals and the like, and the active particles can react with the surface of the substrate to be processed in a plurality of physical and chemical ways, so that the shape of the surface of the substrate W is changed, and the etching process is completed. An exhaust port 140 is also provided below the reaction chamber 101 for exhausting reaction byproducts out of the reaction chamber to maintain a vacuum environment of the reaction chamber.

The lower electrode assembly 103 includes an electrostatic electrode (not shown) for generating electrostatic suction to support and fix the substrate W during the process. A heating device (not shown) is provided below the electrostatic chuck for controlling the temperature of the substrate during processing. A focus ring (not shown) is disposed around the susceptor for adjusting an electric field or temperature distribution around the substrate to improve uniformity of substrate processing. The plasma confinement ring 105 is disposed around the periphery of the lower electrode assembly 103, an exhaust channel is disposed on the plasma confinement ring 105, and by reasonably setting the aspect ratio of the exhaust channel, the plasma is confined in the plasma region P between the upper electrode and the lower electrode assembly 103 while the discharge of the reaction gas is realized, so as to avoid leakage of the plasma to an undesired region and damage to components in the undesired region.

In order to reduce the adverse effect of the transfer port, the plasma processing apparatus 100 further includes a moving ring 104, where the moving ring 104 is connected to a driving device (not shown in the figure) for driving the moving ring 104 to move up and down. When the substrate W surface of the lower electrode assembly 103 is required to be processed, the moving ring 104 is lowered, so that the moving ring 104 covers the substrate W port, the plasma distribution difference in the circumferential direction of the substrate W is smaller, and the uniformity of the substrate W surface treatment is improved.

In this embodiment, the movable ring 104 is made of a conductive material, specifically, the material of the movable ring 104 includes at least one of silicon or silicon carbide, and silicon or silicon carbide is selected as the material of the movable ring 104, so that the movable ring 104 has good electrical conductivity, good electrical connection between the movable ring 104 and the plasma confinement ring 105, and good corrosion resistance of the movable ring 104 without metal contamination, and therefore no additional corrosion-resistant coating is required to be formed on the surface of the movable ring 104.

In another embodiment, the moving ring 104 includes a moving ring body and a first corrosion-resistant coating, wherein the moving ring body is made of a conductive material, and in order to prevent plasma from corroding the moving ring body, the moving ring body is coated with the first corrosion-resistant coating except for a portion of a lower surface of the moving ring body opposite to the plasma confinement ring 103, and the first corrosion-resistant coating is coated on other surfaces of the moving ring, and the portion of the moving ring body not coated with the corrosion-resistant coating is used for subsequent electrical connection with a conductive gasket.

In this embodiment, the plasma confinement ring 105 is schematically shown in fig. 2, and the plasma confinement ring 105 includes a plurality of concentric annular members 1051 and gas passages 1052 formed between adjacent annular members 1051, wherein the annular members 1051 include a confinement ring body and a second corrosion-resistant coating on a surface of the confinement ring body. The material of the confinement ring body is a conductive material, for example, the confinement ring body is made of a metal material, the conductive gasket 106 is disposed on the upper surface of the confinement ring body opposite to the moving ring 104, in order to prevent metal contamination, the second corrosion-resistant coating is disposed on the surface of the confinement ring body around the conductive gasket 106, so that when the moving ring 104 descends to the process position, the moving ring abuts against the conductive gasket 106 and is electrically connected with the conductive gasket 106, and since the conductive gasket 106 is electrically connected with the plasma confinement ring 105 and the plasma confinement ring 105 is grounded, the moving ring 104 is also grounded.

In another embodiment, the material of the plasma confinement ring comprises silicon or silicon carbide. When silicon or silicon carbide is selected as the material of the plasma confinement ring, no additional formation of a second corrosion resistant coating is required as no metal contamination exists.

In this embodiment, the plasma processing apparatus 100 further includes an upper ground ring 107 disposed on the outer periphery of the gas showerhead 102 and between the gas showerhead 102 and the moving ring 104. The upper grounding ring 107 is grounded, the chamber wall of the reaction chamber 101 is grounded, the plasma confinement ring 105 is grounded, and the moving ring 104 is also grounded, so that no potential difference exists between the moving ring 104 and surrounding parts, and therefore, arc discharge is not easy to occur between the moving ring 104 and adjacent parts. Moreover, the movable ring 104 is grounded, so that the plasma has a strong bombardment capability on the surface of the movable ring 104, and the temperature of the surface of the movable ring 104 is high, and therefore, polymer is not easy to deposit on the surface of the movable ring 104.

In addition, in the present embodiment, when the moving ring 104 is at the transfer position, the moving ring 104 is separated from the conductive pad 106, at this time, the moving ring 104 is not grounded, only when the moving ring 104 is lowered to the process position, the moving ring 104 is pressed against the plasma confinement ring 105, the moving ring 104 is electrically connected to the plasma confinement ring 105 through the conductive pad 106, and since the plasma confinement ring 105 is grounded, the moving ring 104 is grounded at the process position. In order to ground the movable ring 104, it is common practice to electrically connect the movable ring 104 with a metal connector, and the movable ring 104 is at a transfer position or a process position, even in the moving process, the movable ring 104 is grounded through the metal connector, however, in the moving process of the movable ring 104 up and down, the metal connector is driven to move, so that the grounding stability of the movable ring 104 is poor. In the present embodiment, the moving ring 104 is not directly grounded, but only grounded during the process, but not grounded during the up-and-down movement, so that the up-and-down movement of the moving ring 104 is not limited by the metal connector, and the situation that the grounding of the moving ring 104 is unstable during the movement is avoided. And, the moving ring 104 is pressed down on the plasma confinement ring 105, so that a sufficient contact area and pressure are provided between the moving ring 104 and the conductive gasket 106, and a stable grounding effect is provided between the moving ring 104 and the plasma confinement ring 105. The structure of the embodiment is relatively simple, the modification to the existing device is small, and the compatibility with the existing plasma processing device is large.

The positional relationship among the plasma confinement ring 105, the movable ring 104, and the conductive gasket 106 is as follows:

in one embodiment, as shown in fig. 3, the plasma confinement ring 105 has a first recess 1053 recessed in an upper surface thereof, the conductive pad 106 is disposed in the first recess 1053, and a lower surface of the movable ring 104 is planar, so that when the movable ring 104 is lowered to a process position, no alignment is required, and only the movable ring 10 is pressed against the conductive pad 106, thereby achieving stable grounding of the movable ring 104 through the conductive pad 106.

In another embodiment, as shown in FIG. 4, except that the plasma confinement ring 105 has a first recess 1053 recessed in its upper surface, the bottom of the conductive pad 106 is disposed within the first recess 1053, except that the moving ring 104 is provided with a second recess 1041 recessed in its lower surface, the second recess 1041 being disposed opposite the first recess 1053, such that the top of the conductive pad 106 can be just placed into the second recess 1041 when the moving ring 104 is lowered to a process position, thereby achieving grounding of the moving ring 104.

The conductive pad 106 is made of at least one of a metal material or a semiconductor material, and the conductive pad 106 is used for electrically connecting the moving ring 104 and the plasma confinement ring 105.

In one embodiment, the conductive pad 106 is a metallic material comprising at least one of copper, beryllium copper, or nickel.

In another embodiment, the conductive pad 106 is made of a metal material, and the material of the conductive pad includes at least one of copper, beryllium copper or nickel, and further includes a metal layer provided on the surface of the conductive pad, and the material of the metal layer includes at least one of silver or gold.

In yet another embodiment, as shown in FIG. 5, the conductive gasket 106 includes an inner member 1061 and a conductive layer 1062 wrapped around a surface of the inner member 1061. The material of the inner part 1061 is an elastic material, for example, a rubber material, and the material of the conductive layer includes at least one of copper, beryllium copper, gold, silver, stainless steel, or nickel. The surface of the conductive layer may also include a metal plating layer, and the material of the metal plating layer includes at least one of silver, gold and nickel. The conductive gasket 106 with such design, because the conductive gasket 106 includes the inner member 1061 made of rubber, makes the conductive gasket 106 have good elasticity, so that when the moving ring 104 descends to the conductive gasket 106, the conductive gasket 106 can be pressed, and the conductive gasket 106, the moving ring 104 and the plasma confinement ring 105 have good grounding effect.

In this embodiment, the conductive pad 106 is in a ring-like structure, which has the advantage of making the interface between the entire movable ring 104 and the plasma confinement ring 105 RF-grounded, so that the movable ring 104 has better electrical grounding.

In other embodiments, the conductive pad 106 may also be an arcuate structure.

Fig. 6 is a schematic view showing the structure of another plasma processing apparatus according to the present invention, and fig. 7 is a top view of a plasma confinement ring and a conductive gasket in the embodiment of fig. 6.

In this embodiment, the materials, positions and functions of the moving ring 204, the plasma confinement ring 205 and the conductive pad 206 in the plasma processing apparatus 200 are the same as those in the embodiment of fig. 1, and are not described herein.

The embodiment of fig. 6 is similar to the embodiment of fig. 1, except that it further includes a sealing ring 208 disposed on the inner side of the conductive pad 206, for blocking plasma and reducing corrosion of the conductive pad 206 by the plasma.

In this embodiment, the seal 208 comprises rubber.

The top of the plasma confinement ring 205 is further provided with a third recess recessed in its upper surface for receiving the sealing ring 208.

The above embodiments have been described taking the example that the conductive pad 206 is disposed on the upper surface of the plasma confinement ring 205, and in practice, the conductive pad 206 may be disposed on the lower surface of the moving ring 204. Specifically, the movable ring 204 is provided with a fourth groove recessed in a lower surface thereof, and the fourth groove is used for placing the conductive pad.

In one embodiment, the material of the moving ring comprises silicon or silicon carbide.

In another embodiment, the movable ring comprises a movable ring body and a first corrosion-resistant coating, the material of the movable ring body is a conductor material, the fourth groove is formed in the lower surface of the movable ring body, the first corrosion-resistant coating is not formed on the side wall and the bottom wall of the fourth groove, and the first corrosion-resistant coating is formed on the surface of the constraint ring body around the fourth groove.

The principle of arranging the conductive gasket on the lower surface of the movable ring is the same as that of arranging the conductive gasket on the upper surface of the plasma confinement ring, and the movable ring is electrically connected with the plasma confinement ring through the conductive gasket to be grounded only when the movable ring descends to the process position, besides, the movable ring is not grounded, so that the movable ring is not influenced by the metal connecting piece in the process of moving up and down. When the movable ring is lowered to the process position, the movable ring is grounded, so that the bombardment of plasma on the movable ring is severe, the temperature of the movable ring is high, and therefore, polymers are not easy to deposit on the surface of the movable ring, and particle pollution is reduced.

Further, the upper grounding ring, the plasma confinement ring and the chamber wall of the reaction chamber are all grounded, and the moving ring is also grounded, so that no potential difference exists between the moving ring and surrounding components, and therefore, arc discharge is not easy to occur between the moving ring and the surrounding components.

While the present invention has been described in detail through the foregoing description of the preferred embodiment, it should be understood that the foregoing description is not to be considered as limiting the invention. Many modifications and substitutions of the present invention will become apparent to those of ordinary skill in the art upon reading the foregoing. Accordingly, the scope of the invention should be limited only by the attached claims.

Claims (19)

1. A plasma processing apparatus includes a reaction chamber;

The gas spray head is arranged at the top of the reaction cavity;

The lower electrode assembly is arranged at the bottom of the reaction cavity and is opposite to the gas spray head;

The conductive movable ring is arranged on the periphery of the gas spray header and can move up and down;

a grounded plasma confinement ring disposed about a periphery of the lower electrode assembly;

The conductive gasket is arranged between the plasma confinement ring and the movable ring, and when the movable ring moves downwards to a process position, the movable ring is electrically connected with the plasma confinement ring through the conductive gasket so as to be grounded.

2. The plasma processing apparatus of claim 1 wherein the conductive pad is at least one of a metallic material or a semiconductor material.

3. The plasma processing apparatus according to claim 2, wherein when the conductive pad is a metal material, the material of the conductive pad includes at least one of copper, beryllium copper, or nickel.

4. The plasma processing apparatus according to claim 3, further comprising a metal layer provided on a surface of said conductive pad, wherein a material of said metal layer comprises at least one of silver, gold and nickel.

5. The plasma processing apparatus as recited in claim 1 wherein said conductive gasket comprises an inner member and a conductive layer wrapped around a surface of said inner member.

6. The plasma processing apparatus according to claim 5, wherein the material of the inner member is a rubber material, and the material of the conductive layer includes at least one of copper, beryllium copper, and nickel.

7. The plasma processing apparatus of claim 1 wherein said conductive gasket is disposed opposite said plasma confinement ring from said motion ring.

8. The plasma processing apparatus of claim 1 wherein said conductive gasket is disposed on an upper surface of said plasma confinement ring.

9. The plasma processing apparatus of claim 8 wherein said plasma confinement ring is provided with a first recess recessed in an upper surface thereof for placement of said conductive gasket.

10. The plasma processing apparatus according to claim 9, wherein the plasma confinement ring comprises a confinement ring body and a second corrosion-resistant coating layer on a surface of the confinement ring body, the confinement ring body is made of a metal material, the confinement ring body is provided with the first groove recessed in an upper surface thereof, the second corrosion-resistant coating layer is not provided on a side wall and a bottom wall of the first groove, and the second corrosion-resistant coating layer is provided on a surface of the confinement ring body around the first groove.

11. The plasma processing apparatus as recited in claim 9 wherein the material of the plasma confinement ring comprises silicon or silicon carbide.

12. The plasma processing apparatus according to claim 9, wherein the lower surface of the moving ring is a plane, or the moving ring is provided with a second recess recessed in the lower surface thereof, the second recess being disposed opposite to the first recess, the second recess being for receiving the top of the conductive pad.

13. The plasma processing apparatus according to claim 1, wherein the gas shower head, the lower electrode assembly and the moving ring enclose a plasma environment when the moving ring moves downward to a process position, and further comprising a sealing ring provided inside the conductive gasket for blocking the plasma and reducing corrosion of the conductive gasket by the plasma.

14. The plasma processing apparatus of claim 13 wherein the top of the plasma confinement ring is further provided with a third recess recessed in an upper surface thereof for receiving the sealing ring.

15. The plasma processing apparatus according to claim 1, wherein the conductive pad is provided on a lower surface of a moving ring, and the moving ring is provided with a fourth groove recessed in a lower surface thereof, the fourth groove being for placing the conductive pad.

16. The plasma processing apparatus as recited in claim 15 wherein the material of the moving ring comprises silicon or silicon carbide.

17. The plasma processing apparatus as recited in claim 15 wherein said traveling ring comprises a traveling ring body and a first corrosion-resistant coating, said traveling ring body being of conductive material, said traveling ring body being provided with a fourth recess recessed in a lower surface thereof, said first corrosion-resistant coating not being provided on a side wall and a bottom wall of said fourth recess, said first corrosion-resistant coating being provided on a surface of said confinement ring body surrounding said fourth recess.

18. The plasma processing apparatus according to claim 1, further comprising a middle ground ring disposed below said plasma confinement ring, said middle ground ring being grounded, said plasma confinement ring being electrically connected to said middle ground ring for grounding.

19. The plasma processing apparatus according to claim 1, further comprising an upper ground ring disposed on an outer periphery of said gas showerhead and between said gas showerhead and said moving ring, said upper ground ring being grounded, and a chamber wall of said reaction chamber being grounded.