Plasma processing apparatus

Abstract

To provide technique for use in suppression of accumulation of impurity in plasma processing.SOLUTION: A plasma processing apparatus is provided, comprising: an edge ring that surrounds an outer perimeter of a processing substrate; a guard ring that surrounds the outer perimeter of the edge ring; and a cover ring that is provided below the edge ring and a guard ring, and is formed from insulating material. An inner periphery of the edge ring is arranged apart from the edge ring, a lower surface of the edge ring is arranged apart from an upper surface of the edge ring. Processing gas during plasma processing passes to between the inner periphery of the edge ring and the outer periphery of the edge ring, and passes to between the lower surface of the edge ring and the upper surface of the edge ring.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a plasma processing apparatus. [Background technology]

[0002] For example, Patent Document 1 discloses a focus ring including a lower member formed in an annular shape and an upper member formed in an annular shape and disposed above the lower member, with a gap formed between the lower member and the upper member to serve as a gas flow path for the process gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-033062 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for suppressing deposition of impurities in a substrate support during plasma processing. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, there is provided a plasma processing apparatus comprising an edge ring surrounding an outer periphery of a processing substrate, a guard ring surrounding the outer periphery of the edge ring, and a cover ring formed of an insulating material and disposed below the edge ring and the guard ring, wherein an inner surface of the guard ring is positioned away from an outer periphery of the edge ring and a lower surface of the guard ring is positioned away from an upper surface of the cover ring, and a processing gas during plasma processing passes between the inner surface of the guard ring and the outer periphery of the edge ring, and passes between the lower surface of the guard ring and the upper surface of the cover ring. Effect of the Invention

[0006] The present disclosure provides techniques for suppressing impurity deposition during plasma processing. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a plasma processing system including a plasma processing apparatus according to this embodiment. [Diagram 2] FIG. 2 is a perspective view of a guard ring provided in the plasma processing apparatus according to this embodiment. [Diagram 3] FIG. 3 is a diagram for explaining an outline of the guard ring and its surroundings provided in the plasma processing apparatus according to this embodiment. [Figure 4] FIG. 4 is a diagram for explaining a flow of a processing gas around a guard ring provided in the plasma processing apparatus according to this embodiment. [Diagram 5] FIG. 5 is a diagram for explaining an outline of a guard ring and its surroundings provided in a modified example of the plasma processing apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments for carrying out the present disclosure will be described with reference to the drawings. In this specification and the drawings, the same reference numerals are used for substantially the same configurations to avoid redundant description. In order to facilitate understanding, the scale of each part in the drawings may differ from the actual scale. In directions such as parallel, right angle, orthogonal, horizontal, vertical, up and down, left and right, deviations are allowed to a degree that does not impair the effects of the embodiment. The shape of the corners is not limited to right angles and may be rounded. Parallel, right angle, orthogonal, horizontal, and vertical may include approximately parallel, approximately right angle, approximately orthogonal, approximately horizontal, and approximately vertical.

[0009] <Plasma processing system> An example of the configuration of the plasma processing system will be described below: Fig. 1 is a diagram illustrating an example of the configuration of a plasma processing system including a plasma processing apparatus 1, which is an example of a plasma processing apparatus according to this embodiment.

[0010] The plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a controller 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed in the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a part of a ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space. The sidewall 10a is grounded. The showerhead 13 and the substrate support 11 are electrically isolated from the plasma processing chamber 10 housing.

[0011] The substrate support 11 includes a main body 111, a ring assembly 112, and a cover ring 113. The main body 111 has a central region (substrate support surface) 111a for supporting a substrate (wafer) W, and an annular region (ring support surface) 111b for supporting the ring assembly 112. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The cover ring 113 is provided on the outside of the main body 111. The cover ring 113 is made of an insulating material. The cover ring 113 is made of, for example, ceramic or quartz. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 and the cover ring 113 so as to surround the substrate W on the central region 111a of the main body 111. In one embodiment, the main body 111 includes a base and an electrostatic chuck. The base includes a conductive member. The conductive member of the base functions as a lower electrode. The electrostatic chuck is disposed on the base. The upper surface of the electrostatic chuck has a substrate support surface 111a. The ring assembly 112 includes one or more annular members. At least one of the one or more annular members is an edge ring. The substrate support 11 includes an edge ring 112a and a guard ring 112b as the ring assembly 112. Although not shown, the substrate support 11 may include a temperature adjustment module configured to adjust at least one of the electrostatic chuck, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111a.

[0012] The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes a conductive member. The conductive member of the shower head 13 functions as an upper electrode. In addition to the shower head 13, the gas introduction unit may include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0013] The gas supply 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply 20 is configured to supply at least one process gas from a respective gas source 21 through a respective flow controller 22 to the showerhead 13. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply 20 may include one or more flow modulation devices to modulate or pulse a flow rate of the at least one process gas.

[0014] The power source 30 includes an RF power source 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power source 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to a conductive member of the substrate support 11 and / or a conductive member of the showerhead 13. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power source 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more processing gases in the plasma processing chamber 10. In addition, by supplying a bias RF signal to the conductive member of the substrate support 11, a bias potential is generated on the substrate W, and ion components in the formed plasma can be attracted to the substrate W.

[0015] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to the conductive member of the substrate support 11 and / or the conductive member of the shower head 13 via at least one impedance matching circuit, and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 13 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to the conductive member of the substrate support 11 and / or the conductive member of the shower head 13. The second RF generating unit 31b is coupled to the conductive member of the substrate support 11 via at least one impedance matching circuit, and is configured to generate a bias RF signal (bias RF power). In one embodiment, the bias RF signal has a lower frequency than the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 400 kHz to 13.56 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated bias RF signal or signals are provided to the conductive members of the substrate support 11. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0016] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to a conductive member of the substrate support 11 and configured to generate a first DC signal. The generated first bias DC signal is applied to the conductive member of the substrate support 11. In one embodiment, the first DC signal may be applied to another electrode, such as an electrode in an electrostatic chuck. In one embodiment, the second DC generator 32b is connected to a conductive member of the showerhead 13 and configured to generate a second DC signal. The generated second DC signal is applied to the conductive member of the showerhead 13. In various embodiments, at least one of the first and second DC signals may be pulsed. The first and second DC generating units 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided in place of the second RF generating unit 31b.

[0017] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0018] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various steps described in the present disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various steps described herein. In one embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control operations based on a program stored in the storage unit 2a2. The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0019] A description will now be given of the ring assembly 112 included in the plasma processing apparatus 1. An edge ring 112a in the ring assembly 112 is provided so as to surround the outer periphery of the substrate W. A guard ring 112b is provided so as to surround the outer periphery of the edge ring 112a.

[0020] The guard ring 112b included in the ring assembly 112 will be described. Fig. 2 is a perspective view of the guard ring 112b included in the ring assembly 112 of the plasma processing apparatus 1, which is an example of the plasma processing apparatus according to this embodiment. More specifically, Fig. 2 is a perspective view of the guard ring 112b as viewed obliquely from below.

[0021] The guard ring 112b has a circular ring shape in a top view. The guard ring 112b has an upper surface 112bA (see FIG. 3), a lower surface 112bB, an inner peripheral surface 112bC, and an outer peripheral surface 112bD. The upper surface 112bA is exposed to the plasma processing space 10s. The lower surface 112bB faces an upper surface 113A (see FIG. 3) of the cover ring 113. The inner peripheral surface 112bC faces an outer peripheral surface 112aD (see FIG. 3) of the edge ring 112a.

[0022] The guard ring 112b has an annular portion 112ba and a plurality of legs 112bb. In the example of Fig. 3, the guard ring 112b has six legs 112bb, but the number of legs 112bb is not limited to six and may be any number.

[0023] The annular portion 112ba constitutes the main body of the guard ring 112b. The annular portion 112ba has an upper surface 112bA, a lower surface 112bB, an inner peripheral surface 112bC, and an outer peripheral surface 112bD of the guard ring 112b (see FIG. 3).

[0024] The legs 112bb are provided to protrude downward from the lower surface 112bB. Since the guard ring 112b is provided with the legs 112bb, the lower surface 112bB of the guard ring 112b is provided at a distance from the upper surface 113A of the cover ring 113 (see FIG. 3).

[0025] The guard ring 112b may be entirely made of an insulating material. For example, the guard ring 112b may be made of quartz. When the guard ring 112b is made of an insulating material, the annular portion 112ba and the multiple legs 112bb may be integrally formed. The guard ring 112b may also be made of a combination of a conductive material and an insulating material. For example, the multiple legs 112bb of the guard ring 112b may be made of an insulating material, such as quartz, and the annular portion 112ba may be made of a conductive material, such as silicon.

[0026] Next, the positional relationship between the edge ring 112a and the guard ring 112b and the cover ring 113 when the edge ring 112a and the guard ring 112b are installed in the plasma processing apparatus 1 will be described.

[0027] 3 is a diagram for explaining an outline of the guard ring 112b and its periphery provided in the ring assembly 112 of the plasma processing apparatus 1 according to the present embodiment. FIG 3 is a diagram for explaining an outline of the guard ring 112b and its periphery indicated by the arrow A in FIG 1.

[0028] The edge ring 112a has an upper surface 112aA, a lower surface 112aB, and an outer circumferential surface 112aD. The upper surface 112aA is exposed to the plasma processing space 10s. The upper surface 112aA is provided at a position higher than the substrate W. The lower surface 112aB faces the annular region 111b of the substrate support 11 and the upper surface 113A of the cover ring 113. The outer circumferential surface 112aD faces an inner circumferential surface 112bC of the guard ring 112b.

[0029] The cover ring 113 is provided under the ring assembly 112, i.e., the edge ring 112a and the guard ring 112b. The cover ring 113 has an upper surface 113A and an outer circumferential surface 113D. The upper surface 113A faces a lower surface 112aB of the edge ring 112a and a lower surface 112bB of the guard ring 112b.

[0030] An inner peripheral surface 112bC of the guard ring 112b is disposed outside and spaced from an outer peripheral surface 112aD of the edge ring 112a. Therefore, an opening HA is formed between an upper surface 112aA of the edge ring 112a and an upper surface 112bA of the guard ring 112b. A gas flow path PA is formed between the outer peripheral surface 112aD of the edge ring 112a and the inner peripheral surface 112bC of the guard ring 112b.

[0031] A lower surface 112bB of the guard ring 112b is disposed above and spaced apart from an upper surface 113A of the cover ring 113. Therefore, an opening HB is formed between an outer circumferential surface 112bD of the guard ring 112b and an outer circumferential surface 113D of the cover ring 113. A gas flow path PB is formed between the lower surface 112bB of the guard ring 112b and an upper surface 113A of the cover ring 113.

[0032] A lower surface 112aB of the edge ring 112a is separated from an upper surface 113A of the cover ring 113. Therefore, a space SP1 is formed below the edge ring 112a between the lower surface 112aB of the edge ring 112a and the upper surface 113A of the cover ring 113. The inside of the space SP1 is a space that continues to the main body 111. Note that there is no space inside the space SP1 through which gas can pass, and the space SP1 is a space with a closed inside.

[0033] A distance H1 between a lower surface 112aB of the edge ring 112a and an upper surface 113A of the cover ring 113 is larger than a distance H2 between a lower surface 112bB of the guard ring 112b and an upper surface 113A of the cover ring 113.

[0034] Next, the flow of the processing gas during plasma processing will be described. Fig. 4 is a schematic diagram for explaining the flow of the processing gas around the guard ring 112b provided in the ring assembly 112 of the plasma processing apparatus 1, which is an example of the plasma processing apparatus according to this embodiment.

[0035] The processing gas PG supplied from the shower head 13 to the plasma processing space 10s passes laterally through the plasma processing space 10s above the edge ring 112a and the guard ring 112b from the center to the outer periphery of the plasma processing chamber 10. Then, the processing gas PG passes beside the outer periphery surface 112bD of the guard ring 112b and the outer periphery surface 113D of the cover ring 113, and flows into the exhaust system 40.

[0036] The pressure of the processing gas PG at the opening HB is lower than the pressure of the processing gas PG at the opening HA, which is the upstream side of the processing gas PG. Therefore, a part of the processing gas PG passes through the opening HA as the processing gas PGb, through the flow path PA and the flow path PB, and is discharged from the opening HB. In other words, the processing gas PGb, which is a part of the processing gas PG during plasma processing, passes between the inner circumferential surface 112bC of the guard ring 112b and the outer circumferential surface 112aD of the edge ring 112a (flow path PA). Then, the processing gas PGb that has passed through the flow path PA passes between the lower surface 112bB of the guard ring 112b and the upper surface 113A of the cover ring 113 (flow path PB). On the other hand, since the inside of the space SP1 is closed, the processing gas PGb does not flow into the space SP1.

[0037] If the flow path PB is not formed, impurities such as by-products and foreign matter contained in the process gas PG will enter the space SP1 from the flow path PA. The impurities that have entered the space SP1 will adhere to the lower surface 112aB of the edge ring 112a, etc. The adhered impurities may cause arcing.

[0038] In the plasma processing apparatus 1, a flow path PB is formed between the lower surface 112bB of the guard ring 112b and the upper surface 113A of the cover ring 113, so that impurities entering from the opening HA are caused to flow to the opening HB by the processing gas PGb branched from the processing gas PG. By causing the impurities entering from the opening HA to flow to the opening HB by the processing gas PGb branched from the processing gas PG, it is possible to suppress the impurities from accumulating in the space SP1 and adhering to the periphery of the space SP1.

[0039] The occurrence of arcing can be suppressed by suppressing impurities from accumulating in the space SP1 and adhering to the periphery of the space SP1. Even if the flow path PB is formed, impurities may enter the space SP1, but since gas is discharged from the flow path PB, gas is less likely to remain in the space SP1 compared to a case in which the flow path PB is not formed, and the accumulation of impurities in the substrate support 11 can be suppressed.

[0040] Next, a modified example of the plasma processing apparatus according to the present embodiment will be described. In the modified example of the plasma processing apparatus according to the present embodiment, a convex ring 114 is provided between the edge ring 112a and the cover ring 113. Fig. 5 is a diagram for explaining a schematic overview of the periphery of the guard ring 112b provided in the modified example of the plasma processing apparatus according to the present embodiment.

[0041] The convex ring 114 is provided between the edge ring 112a and the cover ring 113. The convex ring 114 is placed on the upper surface 113A of the cover ring 113. The edge ring 112a is placed on the convex ring 114. The convex ring 114 contacts the lower surface 112aB of the edge ring 112a. The outer peripheral surface 114D of the convex ring 114 is disposed so as to be recessed inward from the outer peripheral surface 112aD of the edge ring 112a. The convex ring 114 is formed in a ring shape. The convex ring 114 is formed of an insulating material. The convex ring 114 is formed of, for example, ceramic or quartz.

[0042] By providing the convex ring 114, the plasma processing apparatus can reduce the volume of the space SP1a between the edge ring 112a and the cover ring 113 compared to a case in which the convex ring 114 is not provided. By reducing the volume of the space SP1a, the space in which impurities accumulate is reduced, making it difficult for the impurities to enter the back of the space SP1a. Then, on the side of the space SP1a on the flow path PA and flow path PB side, the gas constantly flowing from the flow path PA to the flow path PB blows away the impurities in the space SP1a that are relatively close to this gas path with the gas flow, and moves the impurities to the flow path PB, thereby suppressing the accumulation of the impurities.

[0043] The substrate W is an example of a processing substrate.

[0044] The plasma processing apparatus according to the present embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The above-described embodiment can be modified and improved in various forms without departing from the scope and spirit of the appended claims. The matters described in the above-described embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0045] The above disclosed embodiments include, for example, the following aspects. (Appendix 1) an edge ring surrounding the outer periphery of the processing substrate; a guard ring surrounding the outer periphery of the edge ring; a cover ring provided under the edge ring and the guard ring and made of an insulating material; Equipped with an inner circumferential surface of the guard ring is spaced apart from an outer circumferential surface of the edge ring; a lower surface of the guard ring is spaced apart from an upper surface of the cover ring; a processing gas during plasma processing passes between an inner peripheral surface of the guard ring and an outer peripheral surface of the edge ring, and passes between a lower surface of the guard ring and an upper surface of the cover ring; Plasma processing equipment.

[0046] (Appendix 2) a lower surface of the edge ring spaced apart from an upper surface of the cover ring; 2. The plasma processing apparatus according to claim 1.

[0047] (Appendix 3) a gap between the lower surface of the edge ring and the upper surface of the cover ring is wider than a gap between the lower surface of the guard ring and the upper surface of the cover ring; 3. The plasma processing apparatus according to claim 1 or 2.

[0048] (Appendix 4) The upper surface of the edge ring is positioned above the processing substrate. 4. The plasma processing apparatus according to claim 1,

[0049] (Appendix 5) a convex ring between the edge ring and the cover ring; 5. The plasma processing apparatus according to claim 1,

[0050] (Appendix 6) The convex ring is made of an insulating material. 6. The plasma processing apparatus according to claim 5.

[0051] (Appendix 7) The outer circumferential surface of the convex ring is located inside the outer circumferential surface of the edge ring. 11. The plasma processing apparatus according to claim 5 or 6.

[0052] (Appendix 8) The guard ring is formed of an insulating material. 8. The plasma processing apparatus according to claim 1,

[0053] (Appendix 9) The guard ring is an annular portion formed of a conductive material; A leg portion formed of an insulating material; having 8. The plasma processing apparatus according to claim 1, [Explanation of symbols]

[0054] 1. Plasma processing equipment 10 Plasma Processing Chamber 11 Substrate support 13. Shower Head 20 Gas supply section 30 power supply 40 Exhaust system 111 Main body 112 Ring Assembly 112a エッジリング 112aA Above 112aB Below 112aD Outer surface 112b ガードリング 112bA Above 112bB Below 112bC Inner Surface 112bD Outer surface 112ba ring part 112bb Foot 113 カバーリング 113A Above 113D Outer Surface 114 コンベックスリング HA, HB opening PA, PB flow path SP1, SP1a space W substrate(ウェハ)

Claims

1. an edge ring surrounding the outer periphery of the processing substrate; a guard ring surrounding the outer periphery of the edge ring; a cover ring provided under the edge ring and the guard ring and made of an insulating material; Equipped with an inner circumferential surface of the guard ring is spaced apart from an outer circumferential surface of the edge ring; a lower surface of the guard ring is spaced apart from an upper surface of the cover ring; a processing gas during plasma processing passes between an inner peripheral surface of the guard ring and an outer peripheral surface of the edge ring, and passes between a lower surface of the guard ring and an upper surface of the cover ring; Plasma processing equipment.

2. a lower surface of the edge ring spaced apart from an upper surface of the cover ring; The plasma processing apparatus according to claim 1 .

3. a gap between the lower surface of the edge ring and the upper surface of the cover ring is wider than a gap between the lower surface of the guard ring and the upper surface of the cover ring; The plasma processing apparatus according to claim 2 .

4. The upper surface of the edge ring is positioned above the processing substrate. The plasma processing apparatus according to claim 1 .

5. a convex ring between the edge ring and the cover ring; The plasma processing apparatus according to claim 1 .

6. The convex ring is made of an insulating material. The plasma processing apparatus according to claim 5 .

7. The outer circumferential surface of the convex ring is located inside the outer circumferential surface of the edge ring. The plasma processing apparatus according to claim 5 .

8. The guard ring is formed of an insulating material. The plasma processing apparatus according to claim 1 .

9. The guard ring is an annular portion formed of a conductive material; A leg portion formed of an insulating material; having The plasma processing apparatus according to claim 1 .

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