JP2011124293A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus capable of achieving more uniform processing. <P>SOLUTION: The plasma processing apparatus is disclosed in which a wafer mounted on a sample stage arranged in a processing chamber in a vacuum vessel is processed using a plasma formed in the processing chamber. The plasma processing apparatus includes a dielectric bell jar that makes up the upper part of the vacuum vessel and surrounds the processing chamber; a coil-shaped antenna that is arranged in a state that is wound on the outer periphery of the bell jar and supplied with the high-frequency power to form the plasma; and a Faraday shield of a conductive material that is formed of double layers including inner and outer layers arranged in spaced relation to each other between the antenna and the bell jar, each layer having a plurality of slits and set at a predetermined potential. The slits of the inner and outer layers of the Faraday shield are arranged so as to be covered in staggered fashion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus that performs processing such as etching on a sample using plasma formed in a processing chamber by supplying a high frequency to a coiled antenna wound around the outer periphery of a processing container.

  In the etching apparatus as described above, in general, a reaction product formed from the material constituting the film disposed on the surface of the substrate-like sample such as a semiconductor wafer to be etched and the kind of the processing gas is processed in the processing container. It adheres to the inner wall surface of the processing chamber disposed inside the chamber. It is known that when the amount of such non-adhering material deposited on the surface of the inner wall becomes large, it will peel off or dissociate from the surface of the wall and re-adhere to the surface of the sample, causing foreign matter to contaminate it. It has been.

In addition, it is known that the deposition of such a product lowers the stability of the process when, for example, Al ₂ O ₃ is etched with Cl ₂ or SiO ₂ is etched with CF or the like. Therefore, conventionally, there has been known a technique having a configuration for reducing the adhesion of a product on the wall surface of the processing chamber.

  For example, by setting a Faraday shield between the coiled antenna and the plasma arranged so as to wrap around the outside of the vacuum vessel and supplying high frequency power to this, the deposition of the inner wall of the vacuum vessel is suppressed, Or what can be removed is known. As an example of such a prior art, what was disclosed by Unexamined-Japanese-Patent No. 2000-323298 (patent document 1) is known. In Patent Document 1, plasma generated by an induction electric field or magnetic field is formed inside a processing container made of an insulator by high-frequency power supplied to a coiled antenna. Charged particles constituting this plasma are supplied to a Faraday shield. There is disclosed a technique that removes by pulling in a potential difference with a predetermined magnitude of electric potential maintained on the inner wall surface of the processing vessel by the generated electric power and colliding with a product on the inner wall surface.

  Furthermore, as one method for constructing such a Faraday shield, there is known a method in which a specific metal film is disposed on the outer wall surface of a processing vessel and functions as a Faraday shield. For example, Japanese Patent Application Laid-Open No. 2004-235545 (Patent Document 2) discloses a technique of spraying a tungsten film on the outer wall surface of an insulating processing container.

JP 2000-323298 A JP 2004-235545 A

  In the above-described prior art, problems have arisen because the following points are not sufficiently considered.

  That is, as disclosed in Patent Document 2, in the case where a film is formed on the outer surface of the vacuum vessel, there is no gap between the Faraday shield of the film and the outer wall surface between the vacuum vessels, thereby the static between the Faraday shield and the plasma. The electric capacity can be made as small as possible. And, for this reason, while the effect of suppressing or removing deposition can be improved as compared with the conventional one, the shape of the formed Faraday shield in the surface direction is conventionally constituted by a plate-like member. Since the shape has a slit extending in the vertical direction (vertical direction), the Faraday seed is supplied to the inner wall surface inside the processing vessel corresponding to the space inside the slit. The electrostatic field formed by the generated power does not work.

  In other words, charged particles are not drawn into the inner wall surface of the vacuum vessel in this slit portion, or charged particles are compared to the left and right non-slit portions (inner wall surface covered with a plate-like or film-like member). The amount of entrainment is greatly reduced, in other words, ion sputtering is reduced. For this reason, there is a large difference in the amount of product adhesion and the amount of deposition on the inner surface of the vacuum vessel inner wall corresponding to the slit portion and the non-slit portion, and it is difficult to remove the deposit uniformly. It was. This is because the processing is negatively uniform and unstable in the circumferential direction of the sample (circumferential direction of a processing vessel having a cylindrical shape or a cone (trapezoid) shape), and the above-described Faraday shield configuration impairs the realization of uniform processing. There was a problem that it would end up.

  The objective of this invention is providing the plasma processing apparatus which can implement | achieve a more uniform process. Another object of the present invention is to provide a plasma processing apparatus that improves the yield by suppressing the generation of foreign matter.

  An object of the present invention is a plasma processing apparatus for processing a wafer placed on a sample stage disposed in a processing chamber inside a vacuum chamber using plasma formed in the processing chamber, and constituting an upper portion of the vacuum chamber. A dielectric bell jar surrounding the processing chamber, a coiled antenna wound around the bell jar and supplied with high-frequency power to form the plasma, and between the antenna and the bell jar And a Faraday shield made of a conductor which is arranged in a double manner with a gap between the inner side and the outer side, each having a plurality of slits and being set to a predetermined potential, and the outer Faraday shield and the inner Faraday shield. Is achieved by a plasma processing apparatus disposed at a position where each slit alternately covers.

  Further, this is achieved by the Faraday shield being composed of a plurality of film layers disposed on the outer peripheral wall surface of the bell jar.

  Furthermore, this is achieved by supplying high-frequency power to the Faraday shield.

  Furthermore, this is achieved by arranging the member between the adjacent slits of the outer Faraday shield so as to cover the entire gap in the circumferential direction of the wafer of the slits of the inner Faraday shield.

  Furthermore, this is achieved by disposing an insulating film between the inner and outer Faraday shields.

  Furthermore, this is achieved by forming the inner or outer Faraday shield by thermal spraying.

It is a figure explaining the outline of a structure of the plasma processing apparatus which concerns on the Example of this invention. It is a perspective view which shows typically the structure of a typical prior art Faraday shield. It is a figure which expands and shows the outline of the structure of the Example upper part shown in FIG. FIG. 4 is an enlarged view schematically showing a cross section of the Faraday shield and the bell jar 12 shown in FIG. 3. It is a figure which shows typically distribution of the processing container in the plasma processing apparatus using the Faraday shield which concerns on a prior art, and the electrostatic field or magnetic field inside it. It is a figure which shows typically distribution of the processing container in the Example shown in FIG. 1, and the electrostatic field or magnetic field inside it.

  Embodiments of a plasma processing apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram for explaining the outline of the configuration of a plasma processing apparatus according to an embodiment of the present invention. In the plasma processing apparatus 100 of the present embodiment, a radio wave source or a magnetic field source that has a vacuum vessel 2 that surrounds a vacuum processing chamber and supplies an electric field or a magnetic field that is arranged outside the vessel and is supplied to the vacuum processing chamber. And an exhaust means for exhausting the inside of the container and decompressing it.

  The container is a bell jar made of a cylindrical vacuum container 2 and an insulating material (for example, a non-conductive material such as quartz or ceramic) disposed above and connected to the vacuum container 2 to close the cylindrical space inside. 12 is provided. The bell jar 12 has a trapezoidal shape in vertical section, and has a truncated cone shape having a shape of an axial object around a central axis in the vertical direction passing through the circular center of the cross section. The vacuum processing chamber, which is a space arranged inside these, is surrounded by the inner wall surface of the vacuum vessel 2 and the bell jar 12, and these connections are airtight against the atmospheric pressure atmosphere outside the plasma processing apparatus 100. The inside can be sealed.

  The vacuum processing chamber, which is the space inside the container, includes a mounting table 5 on which a substrate-like sample 13 is mounted so as to be parallel to the inner wall surface of the flat portion at the top of the bell jar 12. Yes. The space inside the vacuum processing chamber above the mounting table 5 is an area where the sample 13 is processed using the plasma 6 that is decompressed to a predetermined degree of vacuum as described later. The mounting table 5 constitutes an upper part of a sample holding unit 9 having a cylindrical shape including the mounting table 5. The space between the outer periphery of the sample holder 9 and the cylindrical inner wall of the vacuum vessel 2 is a space that constitutes a vacuum processing chamber, and includes plasma 6 formed above the sample 13, the supplied processing gas and sample. This is a passage through which a gas containing particles such as a product generated in the process 13 flows downward and is exhausted.

  On the outer peripheral surface of the inclined surface of the bell jar 12, the coiled antenna 1 is disposed by being wound a plurality of times along the outer wall. The antenna 1 of the present embodiment is divided into a plurality of height positions, and an upper antenna 1a and a lower antenna 1b are arranged. Further, a film-like Faraday shield 8 is arranged along the outer surface of the outer surface of the inclined surface of the bell jar 12 so as to cover the inclined surface.

  The bell jar 12 of the present embodiment is attached above the vacuum vessel 2 and is airtightly connected, and its lower end is positioned above the sample mounting surface on the upper surface of the mounting table 5 and a circular lower end is placed thereon. The sample 13 is arranged so as to surround the sample 13 in the circumferential direction. The Faraday shield 8 disposed on the outer peripheral side of the bell jar 12 and the coiled antenna 1 wound and disposed on the outer side of the bell jar 12 are formed with the plasma 6 above the mounting table 5 or the sample 13 mounted thereon. The vacuum processing chamber is arranged so as to surround it from the outer peripheral side.

  The Faraday shield 8 of the present embodiment is disposed so as to cover the outer wall surface including the inclined surface of the bell jar 12 and the flat portion at the top. It is connected in series to a high-frequency power source (first high-frequency power source) 10 via a matching unit (matching box) 3, and has a predetermined potential throughout the processing of the sample 13, and a specific potential as a dielectric. It couple | bonds with the plasma 6 which has it electrostatically. The upper antenna 1a, the lower antenna 1b, and the Faraday shield 8 are also connected to a series resonant circuit (variable capacitor VC3 and reactor L2) that can change the magnitude of the impedance in parallel between the Faraday shield 8 and the ground.

  The potential of the Faraday shield 8 is adjusted so as to become the desired value by the matching unit 3 including the series resonance circuit. In particular, the potential of the Faraday shield 8 of this embodiment can be adjusted to an arbitrary positive or negative value as well as the ground potential. This value draws charged particles in the plasma in the vacuum processing chamber in the direction of the Faraday shield 8, for example. Can be set to collide with the surface of the bell jar 12. The product attached by the collision of the charged particles is released again physically and chemically into the space in the vacuum processing chamber, and the attached matter can be reduced.

  A gas supply pipe 4 a that connects between the vacuum vessel 2 and a gas source 4 of processing gas supplied into the vacuum processing chamber is connected to the upper end of the vacuum vessel 2. The processing gas from the gas source 4 flowing through the gas supply pipe 4a is supplied to the inside through an opening facing the vacuum processing chamber. Further, the gas in the vacuum processing chamber is exhausted from an opening in the lower portion of the vacuum processing chamber connected to the vacuum chamber 2 by the operation of the exhaust device 7 connected to the vacuum chamber 2 below the vacuum chamber 2, so that the inside of the vacuum processing chamber has a predetermined pressure. The pressure is reduced to

  The exhaust device 7 includes an exhaust pump that is generally used in the technical field of the present invention, such as a turbo molecular pump. The opening that communicates this with the inside of the vacuum processing chamber is designed from the central axis of the mounting table 5 below the vacuum vessel 2. They are set apart by a specified horizontal distance. A plurality of exhaust valves are arranged on a passage communicating between this opening and the inlet of the exhaust pump, and rotate around an axis arranged in the horizontal direction to increase or decrease the open area of the passage. The pressure is adjusted by adjusting the flow passage area of the passage and adjusting the displacement rate.

  The processing gas supplied into the vacuum processing chamber through the gas supply pipe 4a is turned into plasma by the action of an electric field or magnetic field generated by the power supplied to the upper antenna 1a and the lower antenna 1b. A substrate bias power source (second high-frequency power source) 11 is connected to the electrode disposed inside the mounting table 5, and the mounting table 5 and the electrode are placed on the mounting table 5 by power supplied to the electrode from the substrate bias power source 11. A bias potential is formed above the sample 13. Depending on the potential difference between the bias potential and the potential of the plasma 6, charged particles such as ions existing in the plasma 6 can be drawn onto the sample 13 and the desired sample 13 can be processed at high speed.

  Note that the power supplied from the high-frequency power supply 10 uses, for example, 13.56 MHz as a frequency or high-frequency power such as a VHF band having a higher frequency. By supplying such high-frequency power to the antenna 1 or the Faraday shield 8, an induction electric field or magnetic field for generating the plasma 6 is formed in the vacuum processing chamber. At this time, the matching unit (matching box) 3 can be used to adjust the impedance of the antenna 1 to match the output impedance of the high-frequency power source 10 so as to suppress the reflection of power. In this embodiment, as the matching unit 3, for example, as shown in the figure, a variable capacitor VC1, VC2 connected in an inverted L shape is used.

  In such an embodiment, a sample such as a semiconductor wafer that has been transported (held by a vacuum robot arm (not shown)) in a transport chamber in a container connected to the outer side wall of the vacuum container 2 and depressurized inside. 13 is transferred onto a plurality of pins on the mounting table 5 in the vacuum processing chamber, and then placed on the circular upper surface of the mounting table 5 and is sucked and held. In a state where the heat transfer gas is supplied between the back surface of the sample 13 and the mounting table 5, the particles of the processing gas supplied into the vacuum processing chamber above the sample 13 are dissociated by the induction electric field or magnetic field supplied from the antenna 1. Thus, plasma by inductive coupling, that is, so-called inductive plasma 6 is formed, and a substrate bias is formed above the sample 13 by the power supplied to the electrode in the mounting table 5, and the processing is performed.

  After the processing is started and it is detected that the predetermined processing of the sample 13 has been completed, the suction is released and the sample 13 is carried out by reversing the loading procedure.

  In the present embodiment, the Faraday shield 8 exhibits an important effect in generating the plasma 6. When the Faraday shield 8 is not provided, each part of the coil of the antenna 1 to which a voltage is applied by the high-frequency power supplied to the antenna 1 has a potential that is arbitrarily determined, and thus has a potential in the coil of the antenna 1 and the vacuum processing chamber. Electrostatic coupling with the plasma 6 occurs, whereby the inner wall surface of the bell jar 12 in the vicinity of the antenna 1 wound around the outer periphery of the inclined surface portion is locally scraped by the collision of charged particles from the plasma 6. Thus, the inner wall surface of the vacuum processing chamber is consumed unevenly.

  Furthermore, the coupling state between the antenna 1 and the plasma 6 in the bell jar 12 changes due to such a change in the state of the wall surface, and etching characteristics on the surface of the sample 13 such as speed and uniformity thereof, processing verticality, etc. Will be adversely affected. In order to reduce such a problem, the plasma 6 and the Faraday shield 8 are installed, and a predetermined potential is applied to the Faraday shield 8 so as to reduce the potential difference between the inner wall surface of the bell jar 12 and the plasma. Further, as in the present invention, the potential supplied to the Faraday shield 8 and formed thereon is adjusted so that the deposits adhered to and deposited on the inner wall surface of the bell jar 12 by collision of charged particles from the plasma 6 are removed. By doing so, it is possible to improve the yield by suppressing the uniformity of processing and the change over time while suppressing the consumption of the inner wall surface of the bell jar 12.

  FIG. 2 is a perspective view schematically showing the configuration of the Faraday shield according to the prior art. In this figure, the upper side of the figure is the upper side of the bell jar 12, and the Faraday shield 8 made of a conductor such as metal is put on the bell jar 12 through a predetermined gap so as to cover the upper surface and the inclined surface. In the portion covering the inclined surface of the Faraday shield 8, a plurality of slits extending in the vertical direction so as to cross the winding direction of the coil of the antenna 1 arranged insulated on the outer peripheral side of the Faraday shield 8 are circular. They are arranged radially around the center axis of the top surface. These slits are arranged for the purpose of introducing a part of them into the inside of the vacuum processing chamber in order to prepare for ignition of the plasma 6 instead of shielding all the electric field or magnetic field formed by the antenna 1.

  In such a processing apparatus using the Faraday shield 8 according to the prior art, the amount of deposits differs between the inner wall surface of the bell jar 12 immediately below the slit portion and the member between the slits of the Faraday shield 8 as shown below. Will occur greatly. That is, the amount of deposits is large on the inner wall surface of the bell jar 12 immediately inside the slit, and the amount of deposits on the inner side between the slits is small. The circumferential direction of the cylindrical shape becomes non-uniform, and the processing of the sample 13 becomes non-uniform in the circumferential direction.

  FIG. 3 is a longitudinal sectional view showing an enlarged main part of the embodiment shown in FIG. As shown in the figure, the bell jar 12 is made of an insulating material (for example, non-conductive material such as quartz or aluminum oxide) and has a trapezoidal longitudinal section and is wound around the outer periphery of the inclined portion of the bell jar 12. Thus, the antenna 1 (upper antenna 1a, lower antenna 1b) is arranged. A Faraday shield 8 is located between the upper antenna 1a and lower portion 1b and the outer peripheral wall surface of the bell jar 1b.

The gas ring 14 is a ring-shaped member disposed below the circular lower end of the bell jar 12 and is disposed so as to surround the outer peripheral side of the vacuum processing chamber. The gas ring 14 is a member disposed at a location where at least one opening through which the supplied processing gas is introduced into the vacuum processing chamber faces the vacuum processing chamber. A processing gas (for example, fluorocarbons such as Cl ₂ , BCl ₃ , C ₄ F ₈ , C ₅ F ₈ , CO, CF _4, etc.) supplied from the gas supply pipe 4 a flows through the gas ring 14. A gas passage (not shown) is arranged. The processing gas that has passed through the gas passage flows out into the vacuum processing chamber from a gas outlet 16 that is installed facing the vacuum processing chamber side of the gas ring 14.

  In the present embodiment, a ring-shaped deposition preventing plate 15 covering the inside of the inner wall surface of the gas ring 14 facing the vacuum processing chamber is disposed through a gap, and the surface of the gas ring 14, particularly the gas outlet 16. It is possible to prevent deposits such as products from accumulating. The processing gas introduced from the gas blowing port 16 into the vacuum processing chamber passes through the blowing opening 15 a formed on the deposition preventing plate 15 and flows into and diffuses into the space above the sample 13. The upper end of the deposition preventing plate 15 is arranged between the lower surface of the bell ring 12 and the upper end surface of the gas ring 14 at the lower end of the bell jar 12 in this embodiment. You may extend and arrange | position so that an inner wall surface may be covered.

In this embodiment, the Faraday shield 8 is composed of a conductive thin film 17 covering the outer peripheral wall surface of the bell jar 12. In particular, as shown in FIG. 3, it is composed of a plurality of film layers. The conductive thin film 17a as the lower film and the conductive thin film 17b (for example, W) as the upper film and the interlayer and the bell jar 12 are connected to each other. An insulating material layer 18 made of, for example, Al ₂ O ₃ is disposed to insulate the gap. The insulating material layer 18 is also composed of a plurality of layers to insulate the plurality of conductive thin films 17a and 17b, and the lower insulating material layer 18a and the upper insulating material layer 18b are alternately laminated with the conductive thin films 17a and 17b. Has been placed.

  These film layers are formed on the outer surface of the bell jar 12 by a specific film forming method. In particular, in this embodiment, they are arranged by thermal spraying. By forming the Faraday shield 8 and the insulating material layer 18 as a thin film by thermal spraying, the thickness can be accurately configured in the circumferential direction and the vertical direction. For this reason, the distance between the Faraday shield 8 and the plasma 6 can be managed with high accuracy, the uniformity of the amount of deposits on the inner wall surface of the bell jar 12 is improved, and the deposition removal on the inner wall surface of the bell jar 12 is made uniform. The

  Furthermore, since the Faraday shield 8 is configured as a plurality of film layers arranged at a predetermined distance, the depot can be removed with a low voltage (Faraday Shield Voltage; FSV) applied to the Faraday shield 8. It becomes possible. Thereby, the consumption of the inner wall surface of the bell jar by the Faraday shield 8 having the slit can be reduced. Details of the Faraday shield bell jar inner wall cleaning principle and the method of optimizing the FSV are described in detail in the aforementioned Patent Document 4.

  FIG. 4 is a cross-sectional view schematically showing an outline of the configuration of the Faraday shield and the vacuum vessel according to the embodiment shown in FIG. As shown in this figure, in this embodiment, the plurality of layers of conductive thin films 17a and 17b constituting the Faraday shield 8 are alternately arranged with the insulating material layers 18a and 18b interposed therebetween, and the slit portions of the Faraday shield 8 are three-dimensionally arranged. It is configured.

  That is, the conductive thin film 17a made of tungsten, the insulating material layer 18a which is a thin film made of alumina, the conductive thin film 17b made of tungsten, and the insulating material layer 18b made of alumina are sequentially formed upward (outside) from the outer peripheral surface of the bell jar 12. is set up. The upper conductive thin film 17b and the lower conductive thin film 17a are respectively disposed so as to cover the entire inclined surface portion and the top of the bell jar 12, and the direction in which the antenna 1 is wound (in the present embodiment, the left-right direction). And a plurality of slit portions extending in the vertical direction.

  These slit portions are arranged to suppress a back electromotive force generated in the Faraday shield 8 by the induction electric field or magnetic field of the antenna 1 or the plasma 6 from flowing in a direction that prevents the formation of the electric field or magnetic field. Or it is arrange | positioned in many places as wide as possible in the range which a magnetic field covers. That is, the configuration of FIG. 2 is provided.

  The film portion between the slits of the upper conductive thin film 17b is disposed so as to cover the lower conductive thin film 17a on the outside (upper) of the slit portion. That is, the conductive thin films 17a and 17b have a configuration in which each slit portion is vertically covered with a member between the other slits. In other words, the conductive thin films 17a and 17b of the Faraday shield 8 arranged in multiple are arranged so that the plurality of slit portions or members between the slits are staggered.

  As shown in FIG. 4, the relative positions of the end portions in the left-right direction of the film portion between the slits of the conductive thin films 17a and 17b may have a gap when viewed in the outer direction (the radial direction). However, the film portions may enter the inside from the end portion and overlap each other. In the present embodiment, the end points of the film portions between the slits overlap with each other on a straight line or are overlapped so that the operation and effect are not significantly impaired.

  On the other hand, when a large gap is formed between the end points of the film portions between the slits of the upper and lower conductive thin films 17a and 17b as indicated by α in the figure, the inner wall surface of the bell jar 12 immediately inside the gap portion α is formed. The product is deposited larger than the surrounding area. Further, when the tungsten thin films are largely overlapped as in β, the larger the overlap region is, the more easily the circulating current is generated between the conductive thin films 17a and 17b via the stray capacitance. At this time, since the induction magnetic field generated from the antenna 1 may be canceled out by the circulating current and it may be difficult to obtain the desired density and distribution of the plasma 6, in order to realize the specifications It is desirable to have an appropriate amount of overlap.

  The thickness of each film that realizes the film layer structure of the Faraday shield 8 of this embodiment is formed such that the conductive thin films 17a and 17b are 100 μm each, and the insulating material layers 18a and 18b are each 150 μm. In the present invention, these thickness values are not limited to those in the present embodiment, and are set to appropriate film thicknesses that do not generate a circular current in the entire conductive thin films 17a and 17b. Furthermore, the width of the slit and the width of the inter-slit film portion are also appropriately selected according to specifications such as the magnitude of the supplied power, the frequency, the material of the bell jar 12, and the thickness.

  Further, in this embodiment, the insulating layer 18b is disposed so as to cover the entire top and the inclined surface of the bell jar 12 together with the lower film layer, and covers the bell jar 12, and the conductive thin films 17a and 17b are outside air. Is no longer exposed. Therefore, when the bell jar 12 is removed from the main body of the plasma processing apparatus 100 and cleaned, the conductive thin films 17a and 17b are less likely to be corroded by contact with the atmosphere or the cleaning material, and the handling is facilitated and the cleaning is facilitated. Efficiency is improved.

  Next, the action of the electrostatic field or magnetic field of this embodiment will be described with reference to FIGS. FIG. 5 is a view schematically showing a processing container and a distribution of an electrostatic field or a magnetic field therein in a plasma processing apparatus using a Faraday shield according to the prior art. FIG. 6 is a diagram schematically showing the distribution of the processing container and the electrostatic or magnetic field therein in the embodiment shown in FIG. In these drawings, the contour lines indicated by thick solid lines connect the equal strengths of the electrostatic field or magnetic field supplied from the Faraday shield 8 or the conductive thin films 17a and 17b. The flatter the contour lines, the more the plasma 6 The magnitude of the action of drawing the charged particles therein becomes flatter, that is, the degree of collision of the charged particles with the inner wall surface of the bell jar 12 becomes more uniform.

  In the configuration of the Faraday shield 8 shown in FIG. 5 according to the prior art, the electrostatic field 20 to be generated from the supplied electric power has a portion where the strength of the electrostatic field 20 is reduced in the slit portion as described above, and the contour lines thereof. Therefore, the electrostatic field 20 reaches the plasma 6 in a non-uniform state on the inner wall surface of the bell jar 12. For this reason, the density and the amount of ions reaching the inner wall surface of the bell jar, and the amount of adhesion, are not uniform in the circumferential direction on the surface.

  On the other hand, in this embodiment, as shown in FIG. 6, the slits of the multi-layered conductive thin films 17a and 17b constituting the Faraday shield 8 are alternately arranged with the insulating material layer 18a interposed therebetween. In this configuration, an electrostatic field or a magnetic field is supplied to the slit portion of the conductive thin film 17a, which is a film below the insulating material layer 18a, and to the upper portion thereof from the film portion between the slits of the upper conductive thin film 17b. The electric or magnetic field increases the strength of the electrostatic or magnetic field of the conductive thin film 17a at the slit (between the film end portions of the lower conductive thin film 17a), thereby increasing the static electric field generated from the conductive thin film 17b. In the state in which the electrostatic field or magnetic field 21 is coupled with the electric field or magnetic field 21 and the electrostatic field or magnetic field 21 reaching the inner wall surface of the bell jar 12 is suppressed by the decrease of the electrostatic field or magnetic field 21 at the slit portion of the conductive thin film 17a below. It can face the plasma 6. For this reason, it is possible to remove the deposit with higher uniformity than in the prior art.

  On the other hand, the slits of the upper and lower conductive thin films 17a and 17b are mutually covered by the film portion, but the induction electric field or magnetic field from the antenna 1 is between the conductive thin films 17a and 17b stacked in the vertical direction. An electric field and a magnetic field can be formed inside the vacuum processing chamber through the bell jar 12 from the slit portion of the conductive thin film 17a through the disposed insulating material layers 18a and 18b. For this reason, the electric field and the magnetic field required to ignite and maintain the plasma 6 are suppressed from being significantly damaged by the Faraday shield 8 having the configuration of the present embodiment as compared with the prior art.

  As described above, according to the present embodiment, the amount of deposits or the amount of wear on the inner wall surface of the vacuum processing chamber whose outer wall surface is covered with the Faraday shield 8 is equalized in the circumferential direction of the sample 13 or the vacuum processing chamber. A plasma processing apparatus with improved reliability and life can be realized. Further, the processing of the sample in the circumferential direction is equalized, or the generation of foreign matters is suppressed and the distribution of foreign matters is equalized, thereby improving the processing efficiency and yield.

  The above-described configuration of the present invention is not limited to this embodiment, and is appropriate according to specifications required within a range that does not impair the operation and effect of equalization of adhesion and treatment, or improvement of reliability and efficiency. You can choose anything. For example, in the present embodiment, high-frequency power is supplied to the Faraday shield 8 and a bias potential is formed on the inner wall surface of the bell jar 12 to draw charged particles. The supplied power may be adjusted so as to be at a potential that is appropriately adhered and maintained at an equal amount.

DESCRIPTION OF SYMBOLS 1 Antenna 2 Vacuum container 3 Matching device 4 Gas source 5 Mounting base 6 Plasma 7 Exhaust device 8 Faraday shield 9 Sample holding part 10 High frequency power supply 11 Substrate bias power supply 12 Berja 13 Sample 14 Gas ring 15 Deposition plate 16 Gas outlet 17 Conductivity Thin film 18 Insulating material layer

Claims (7)

A plasma processing apparatus for processing a wafer placed on a sample stage disposed in a processing chamber inside a vacuum vessel using plasma formed in the processing chamber,
An insulator bell jar that forms an upper part of the vacuum vessel and surrounds the processing chamber; a coiled antenna that is wound around the bell jar and supplied with high-frequency power to form the plasma; and A Faraday shield made of a conductor that is arranged in a double manner with a gap between the antenna and the bell jar between the inside and the outside and each of which has a plurality of slits and has a predetermined potential,
The plasma processing apparatus, wherein the outer Faraday shield and the inner Faraday shield are arranged at positions where respective slits alternately cover.   2. The plasma processing apparatus according to claim 1, wherein the Faraday shield is composed of a plurality of film layers disposed on an outer peripheral wall surface of the bell jar. A sample stage disposed in a processing chamber disposed inside a processing container whose inside is depressurized and on which a circular wafer is placed, and an upper part of the processing container are formed above the sample stage, and an outer periphery of the sample stage is formed. A surrounding insulator bell jar, a coiled antenna wound around the sample stage outside the outer wall surface of the bell jar, a power source for supplying high frequency power to the antenna, and between the bell jar and the antenna A membrane-like Faraday shield disposed at a predetermined potential, and an exhaust means coupled to the lower part of the processing vessel and disposed in communication with the processing chamber,
The Faraday shield is doubled with a gap and each has inner and outer Faraday shields having a plurality of slits, and a member between the plurality of slits of the inner and outer Faraday shields connects the other slit to each other. A plasma processing apparatus disposed in a covering position.   4. The plasma processing apparatus according to claim 1, wherein high-frequency power is supplied to the Faraday shield.   5. The plasma processing apparatus according to claim 1, wherein a member between the adjacent slits of the outer Faraday shield covers the entire gap in the circumferential direction of the wafer of the slit of the inner Faraday shield. Plasma processing apparatus.   6. The plasma processing apparatus according to claim 1, wherein a film made of an insulator is disposed between the inner and outer Faraday shields.   The plasma processing apparatus according to any one of claims 1 to 6, wherein the inner or outer Faraday shield is formed by thermal spraying.

Images