Plasma processing equipment

Abstract

To reduce a potential difference which may occur during plasma processing, between a conductive member provided in the vicinity of the outside of a focus ring and the focus ring.SOLUTION: A conductive ring is mounted on a cover ring. A high frequency power source is coupled to a mounting base. A first power supply line is electrically connected to a focus ring. A second power supply line is electrically connected to the conductive ring. A DC power unit is electrically connected to the focus ring via the first power supply line and electrically connected to the conductive ring via the second power supply line. The DC power unit is configured to apply equal or different DC voltages to the focus ring and the conductive ring. A first surface in an outer peripheral part of the focus ring and a second surface in an inner peripheral part of the conductive ring are isolated while being opposed to each other. The cover ring includes an isolation part isolating the focus ring and the conductive ring.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An exemplary embodiment of the present disclosure relates to a plasma processing apparatus. [Background technology]

[0002] A plasma processing apparatus for performing substrate processing may have a configuration including a focus ring and a cover ring, as disclosed in, for example, Patent Document 1. By disposing a conductive focus ring so as to surround the periphery of a semiconductor substrate, discontinuities in the bias potential at the edge of the substrate are alleviated, improving the uniformity of plasma processing. A quartz cover ring is provided around the periphery of this focus ring (also called an edge ring). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-206913 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for reducing a potential difference that may occur during plasma processing between a focus ring and a conductive member provided near the outside of the focus ring. [Means for solving the problem]

[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a mounting table, a focus ring, a cover ring, a conductive ring, a radio frequency power supply, a first feed line, a second feed line, and a DC power supply. The mounting table has a substrate mounting portion for mounting a substrate thereon and a peripheral portion surrounding the substrate mounting portion. The focus ring is mounted on the peripheral portion of the mounting table and is conductive. The cover ring surrounds the outer periphery of the mounting table and is made of a dielectric material. The conductive ring is mounted on the cover ring. The radio frequency power supply is coupled to the mounting table. The first feed line is electrically connected to the focus ring. The second feed line is electrically connected to the conductive ring. The DC power supply is electrically connected to the focus ring via the first feed line and electrically connected to the conductive ring via the second feed line. The DC power supply is configured to apply the same or different DC voltages to the focus ring and the conductive ring. The first surface on the outer periphery of the focus ring and the second surface on the inner periphery of the conductive ring face each other and are spaced apart from each other. The cover ring has a spacer that separates the focus ring and the conductive ring. [Effects of the Invention]

[0006] According to one exemplary embodiment, a technique is provided for reducing a potential difference that may occur during plasma processing between a focus ring and a conductive member provided near the exterior of the focus ring. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of the configuration of a plasma processing apparatus according to an exemplary embodiment; [Figure 2] 1A and 1B illustrate an example of a conductive ring configuration according to one exemplary embodiment. [Figure 3] 2 is a diagram illustrating an example of the configuration of a direct-current power supply DC illustrated in FIG. 1. FIG. [Figure 4] 1. FIG. 4 is a diagram showing another example of the configuration of the direct-current power supply DC shown in FIG. [Figure 5]FIG. 10 illustrates another example of a conductive ring configuration according to an exemplary embodiment. [Figure 6] FIG. 10 illustrates another example of a conductive ring configuration according to an exemplary embodiment. [Figure 7] FIG. 10 illustrates another example of a conductive ring configuration according to an exemplary embodiment. [Figure 8] FIG. 10 illustrates another example of a conductive ring configuration according to an exemplary embodiment. [Figure 9] FIG. 10 illustrates another example of a conductive ring configuration according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Various exemplary embodiments are described below.

[0009] Etching techniques using plasma processing equipment often require higher power to improve productivity. This requires addressing issues such as accelerated wear of chamber components and increased particle generation due to increased sputtering. To address these issues, a conductive ring (conductive member) made of a highly durable conductive material may be used. The conductive ring is mounted on a cover ring and may form a capacitor with the outer periphery of the focus ring. During plasma processing, the conductive ring, like the focus ring, may develop an offset potential (Vdc). In processes with a high amount of deposits, it is conceivable to reduce the capacitance between the focus ring and the conductive ring to generate a higher Vdc to increase sputtering. However, in such cases, the potential difference between the focus ring and the conductive ring (the electric field within the capacitor) becomes stronger, which can lead to discharge between the focus ring and the conductive ring.

[0010] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a mounting table, a focus ring, a cover ring, a conductive ring, a radio frequency power supply, a first feed line, a second feed line, and a DC power supply. The mounting table has a substrate mounting portion for mounting a substrate thereon and a peripheral portion surrounding the substrate mounting portion. The focus ring is mounted on the peripheral portion of the mounting table and is conductive. The cover ring surrounds the outer periphery of the mounting table and is made of a dielectric material. The conductive ring is mounted on the cover ring. The radio frequency power supply is coupled to the mounting table. The first feed line is electrically connected to the focus ring. The second feed line is electrically connected to the conductive ring. The DC power supply is electrically connected to the focus ring via the first feed line and electrically connected to the conductive ring via the second feed line. The DC power supply is configured to apply the same or different DC voltages to the focus ring and the conductive ring. The first surface on the outer periphery of the focus ring and the second surface on the inner periphery of the conductive ring face each other and are spaced apart from each other. The cover ring has a spacer that separates the focus ring and the conductive ring.

[0011] In this manner, the plasma processing apparatus having the above-described configuration is configured such that the same or different DC voltages can be applied to the focus ring and the conductive ring from the DC power supply via the first and second power feed lines, respectively, and therefore the potential difference between the focus ring and the conductive ring is reduced or eliminated by the DC voltages supplied via the first and second power feed lines, respectively.

[0012] In one exemplary embodiment, the inner periphery of the focus ring is supported by the periphery of the stage, and the outer periphery of the focus ring covers the upper surface of the inner periphery of the cover ring.

[0013] In one exemplary embodiment, the focus ring and the conductive ring are capacitively coupled at the first and second surfaces.

[0014] In one exemplary embodiment, the distance between the first surface and the second surface is greater than zero and less than the thickness of the focus ring.

[0015] In one exemplary embodiment, the lower surface of the inner periphery of the conductive ring is located below the lower surface of the outer periphery of the focus ring.

[0016] In one exemplary embodiment, the separating portion is a stepped portion formed on the surface of the cover ring, configured to be abutted by the side surface of the inner periphery of the conductive ring.

[0017] In one exemplary embodiment, the standoff is a groove formed in the surface of the cover ring, with the lower surface of the inner periphery of the conductive ring received within the groove.

[0018] In one exemplary embodiment, the first surface is an outer peripheral side surface of a focus ring, and the second surface is an inner peripheral side surface of a conductive ring.

[0019] In one exemplary embodiment, the first surface is a lower surface of an outer periphery of the focus ring, and the second surface is an upper surface of an inner periphery of the conductive ring.

[0020] In one exemplary embodiment, an outer peripheral side surface of the focus ring and an inner peripheral side surface of the conductive ring are spaced apart and face each other.

[0021] In one exemplary embodiment, the area of ​​the upper surface of the inner periphery of the conductive ring facing the lower surface of the outer periphery of the focus ring is larger than the area of ​​the side surface of the inner periphery of the conductive ring facing the side surface of the outer periphery of the focus ring.

[0022] In one exemplary embodiment, the gap between the lower surface of the outer periphery of the focus ring and the upper surface of the inner periphery of the conductive ring is narrower than the gap between the side surface of the outer periphery of the focus ring and the side surface of the inner periphery of the conductive ring.

[0023] In one exemplary embodiment, the first surface is an upper surface of an outer periphery of a focus ring, and the second surface is a lower surface of an inner periphery of a conductive ring.

[0024] In one exemplary embodiment, the DC power supply device includes a first filter, a second filter, and a DC power supply. The first filter is electrically connected to the focus ring via a first power supply line. The second filter is electrically connected to the conductive ring via a second power supply line. The DC power supply is electrically connected to the focus ring via the first filter and the first power supply line. The DC power supply is electrically connected to the conductive ring via the second filter and the second power supply line. The DC power supply is configured to apply a common DC voltage to the focus ring and the conductive ring. The first filter and the second filter are configured to block input of high frequency signals output from the high frequency power supply to the DC power supply.

[0025] In one exemplary embodiment, the DC power supply device includes a first DC power supply and a second DC power supply. The first DC power supply is electrically connected to the focus ring via a first power supply line. The first DC power supply is configured to apply a DC voltage to the focus ring. The second DC power supply is electrically connected to the conductive ring via a second power supply line. The second DC power supply is configured to apply a DC voltage to the conductive ring. The first DC power supply and the second DC power supply are configured to output DC voltages independently of each other.

[0026] In one exemplary embodiment, the plasma processing apparatus further includes a controller configured to control DC voltages output from the first DC power supply and the second DC power supply, respectively, so as to reduce a potential difference between the focus ring and the conductive ring.

[0027] In one exemplary embodiment, the control unit controls the DC voltages output from the first DC power supply and the second DC power supply so as to match the potential of the focus ring and the potential of the conductive ring.

[0028] In one exemplary embodiment, the plasma processing apparatus includes a plurality of first feed lines and a plurality of second feed lines. The focus ring has a shape extending along the periphery of the mounting table. The conductive ring has a shape extending to surround the focus ring. The plurality of first feed lines are spaced apart from one another in the circumferential direction of the focus ring. The plurality of second feed lines are spaced apart from one another in the circumferential direction of the conductive ring.

[0029] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0030] A plasma processing apparatus 1 according to one exemplary embodiment includes a chamber 10. The chamber 10 provides an internal space 12c therein. The chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The material of the chamber body 12 may be, for example, aluminum. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. The material of the film may be a ceramic such as aluminum oxide or yttrium oxide.

[0031] A passage 12p is formed in the sidewall of the chamber body 12. The substrate W is transferred between the internal space 12c and the outside of the chamber 10 through the passage 12p. The passage 12p is opened and closed by a gate valve 12g provided along the sidewall of the chamber body 12.

[0032] A cylindrical portion 28 is provided on the bottom of the chamber body 12. The cylindrical portion 28 may be made of an insulating material. The cylindrical portion 28 has a substantially cylindrical shape. The cylindrical portion 28 extends upward from the bottom of the chamber body 12 within the internal space 12c.

[0033] Within the internal space 12c, the support 15 extends upward from the bottom of the chamber body 12 along the inner side surface of the approximately cylindrical tubular portion 28. The support 15 has a generally cylindrical shape. The support 15 may be made of an insulating material such as ceramic. A mounting table 16 is mounted on the support 15. The mounting table 16 is supported by the support 15. The mounting table 16 is configured to support the substrate W within the internal space 12c.

[0034] The mounting table 16 is provided on the support portion 15. The mounting table 16 includes a mounting portion 31, a base 18, and an electrode plate 21.

[0035] The mounting portion 31 includes a substrate mounting portion 31a where the substrate W is mounted, and a peripheral portion 31b surrounding the substrate mounting portion 31a. A conductive focus ring FR is mounted on the peripheral portion 31b. The conductive ring DR is mounted on the cover ring CR concentrically along the outer periphery OPc of the focus ring FR. The mounting portion 31 may be formed of an electrostatic chuck 20.

[0036] The covering CR is provided on the cylindrical portion 28. The covering CR is an insulator and extends along the outer periphery of the mounting table 16. When viewed from above the mounting portion 31 (when viewed from the upper electrode 30 side), the covering CR is provided so as to surround the outer periphery of the mounting portion 31. The covering CR is made of an insulating material, and may be, for example, a ceramic such as quartz or alumina. The covering CR may be composed of multiple dielectric components.

[0037] The conductive ring DR is disposed above the cover ring CR. When viewed from above the mounting portion 31, the conductive ring DR is provided to surround the focus ring FR. The conductive ring DR has a substantially annular plate shape and is made of a conductive material. The material of the conductive ring DR may be, for example, silicon (Si) or silicon carbide (SiC).

[0038] The electrode plate 21 is made of a conductive material such as aluminum and has a substantially disc shape. The base 18 is provided on the electrode plate 21. The base 18 is made of a conductive material such as aluminum and has a substantially disc shape. The base 18 is electrically connected to the electrode plate 21 and functions as a lower electrode.

[0039] The electrostatic chuck 20 is provided on the base 18 as a mounting portion 31. A substrate W is mounted on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body and an electrode. The main body of the electrostatic chuck 20 has a substantially disk shape. The main body of the electrostatic chuck 20 is made of a dielectric material. The electrode of the electrostatic chuck 20 is a film-like electrode and is provided inside the main body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the electrode of the electrostatic chuck 20, an electrostatic attractive force is generated between the electrostatic chuck 20 and the substrate W. The substrate W is held by the electrostatic chuck 20 by the electrostatic attractive force.

[0040] The focus ring FR is disposed in the peripheral portion 31b so as to surround the outer periphery of the substrate W placed on the substrate placement portion 31a. The focus ring FR improves the in-plane uniformity of the plasma processing on the substrate W. The focus ring FR has a substantially annular plate shape and is made of a conductive material. The material of the focus ring FR may be, for example, silicon (Si) or silicon carbide (SiC).

[0041] A flow path 18f is provided inside the base 18. A heat exchange medium (e.g., a refrigerant) is supplied to the flow path 18f from a chiller unit (not shown) provided outside the chamber 10 via a pipe 23a. The heat exchange medium supplied to the flow path 18f is returned to the chiller unit via a pipe 23b. In the plasma processing apparatus 1, the temperature of the substrate W placed on the electrostatic chuck 20 can be adjusted by heat exchange between the heat exchange medium and the base 18.

[0042] The plasma processing apparatus 1 is provided with a gas supply line 25. The gas supply line 25 supplies a heat transfer gas (for example, He gas) from a heat transfer gas supply mechanism to between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

[0043] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the mounting table 16. The upper electrode 30 is supported on the upper part of the chamber body 12 via a member 32. The member 32 may be made of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the chamber body 12.

[0044] The upper electrode 30 may include a top plate 34 and a support 36. The bottom surface of the top plate 34 is the bottom surface on the side of the internal space 12c and defines the internal space 12c. The top plate 34 may be formed from a low-resistance conductor or semiconductor that generates little Joule heat. The top plate 34 has a plurality of gas discharge holes 34a that penetrate the top plate 34 in its thickness direction.

[0045] The support 36 detachably supports the top plate 34. The support 36 may be made of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support 36. The support 36 has a plurality of gas holes 36b extending downward from the gas diffusion chamber 36a. The plurality of gas holes 36b are connected to the plurality of gas discharge holes 34a, respectively. A gas inlet 36c is formed in the support 36. The gas inlet 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet 36c.

[0046] A valve group 44, a flow rate controller group 42, and a gas source group 40 are connected to the gas supply pipe 38. The gas source group 40, the valve group 44, and the flow rate controller group 42 constitute a gas supply unit. The gas source group 40 includes a plurality of gas sources. The valve group 44 includes a plurality of on-off valves. The flow rate controller group 42 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers in the flow rate controller group 42 is a mass flow controller or a pressure-controlled flow rate controller. Each of the plurality of gas sources in the gas source group 40 is connected to the gas supply pipe 38 via a corresponding on-off valve in the valve group 44 and a corresponding flow rate controller in the flow rate controller group 42.

[0047] A baffle plate 48 is provided between the cylindrical portion 28 and the side wall of the chamber body 12. The baffle plate 48 is formed, for example, by forming a corrosion-resistant film (a film of yttrium oxide or the like) on the surface of a base material made of aluminum. A plurality of through holes are formed in the baffle plate 48. An exhaust port is provided below the baffle plate 48 and at the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust port via an exhaust pipe 52. The exhaust device 50 includes a pressure adjustment valve and a vacuum pump such as a turbomolecular pump.

[0048] The plasma processing apparatus 1 includes a first high-frequency power supply 62 and a second high-frequency power supply 64. The first high-frequency power supply 62 is a power supply that generates a first high-frequency power. The first high-frequency power has a frequency suitable for generating plasma. The frequency of the first high-frequency power is, for example, within the range of 27 to 100 MHz. The first high-frequency power supply 62 is connected to the base 18 via a matching box 66 and the electrode plate 21. The matching box 66 has a circuit for matching the output impedance of the first high-frequency power supply 62 with the impedance on the load side (the side of the base 18). The first high-frequency power supply 62 may also be connected to the upper electrode 30 via the matching box 66.

[0049] The second high-frequency power supply 64 is a power supply that generates second high-frequency power. The second high-frequency power has a frequency lower than that of the first high-frequency power. When the second high-frequency power is used together with the first high-frequency power, the second high-frequency power is used as bias high-frequency power for attracting ions into the substrate W. The frequency of the second high-frequency power is, for example, within a range of 400 kHz to 13.56 MHz. The second high-frequency power supply 64 is connected to the base 18 via a matching box 68 and the electrode plate 21. The matching box 68 has a circuit for matching the output impedance of the second high-frequency power supply 64 with the impedance on the load side (the base 18 side). Alternatively, a bias DC voltage for attracting ions into the substrate W may be applied instead of the second high-frequency power. The bias DC voltage may be a negative voltage pulse. Alternatively, the bias DC voltage may be applied to an electrode provided inside the electrostatic chuck 20.

[0050] Alternatively, plasma may be generated using the second high-frequency power without using the first high-frequency power, i.e., using only a single high-frequency power. In this case, the frequency of the second high-frequency power may be greater than 13.56 MHz, for example, 40 MHz. The plasma processing apparatus 1 may not include the first high-frequency power supply 62 and the matching box 66.

[0051] In the plasma processing apparatus 1, a gas is supplied from the gas supply unit to the internal space 12c to generate plasma. By supplying at least one of the first high-frequency power and the second high-frequency power, a high-frequency electric field is generated between the upper electrode 30 and the base 18 (lower electrode). The generated high-frequency electric field generates plasma.

[0052] The plasma processing apparatus 1 may further include a control unit MC. The control unit MC may be a computer including a processor, a storage unit such as a memory, an input device, a display device, a signal input / output interface, etc. The control unit MC controls each unit of the plasma processing apparatus 1.

[0053] In the control unit MC, an operator can use an input device to input commands and perform other operations to manage the plasma processing apparatus 1. In addition, the control unit MC can visualize and display the operating status of the plasma processing apparatus 1 using a display device. Furthermore, a control program and recipe data are stored in the memory unit. The control program is executed by a processor to perform various processes in the plasma processing apparatus 1. The processor executes the control program and controls each part of the plasma processing apparatus 1 in accordance with the recipe data.

[0054] 2 in addition to Fig. 1, the configuration of the region ER of the mounting table 16 shown in Fig. 1 will be further described. In particular, the configurations of the conductive ring DR and the focus ring FR will be described in detail.

[0055] As shown in the example of Fig. 2, the covering CR is composed of two dielectric members, an inner covering CRa and an outer covering CRb. The covering CR may be composed of one dielectric member or three or more dielectric members.

[0056] The inner circumferential side (inner peripheral portion) of the focus ring FR is placed on the electrostatic chuck 20, which is the peripheral portion 31b of the mounting portion 31, and the outer circumferential side (outer peripheral portion) is disposed so as to cover the inner covering ring CRa. The outer circumferential portion of the focus ring FR may be placed on the inner covering ring CRa. To ensure that the inner circumferential portion of the focus ring FR is supported by the peripheral portion 31b, the upper surface SFa of the inner covering ring CRa may be formed lower than the upper surface of the peripheral portion 31b, thereby providing a gap between the lower surface of the outer circumferential portion of the focus ring FR and the upper surface SFa of the inner covering ring CRa. In other words, the outer circumferential portion of the focus ring FR does not have to be placed on the inner covering ring CRa. The thickness of the main body of the electrostatic chuck 20 is extremely small compared to the thickness of the inner covering ring CRa. Therefore, the focus ring FR is coupled to the first high-frequency power supply 62 and the second high-frequency power supply 64 via the electrostatic chuck 20 as a high-frequency circuit.

[0057] The power supply line SP is electrically connected to the focus ring FR. The power supply line SQ is electrically connected to the conductive ring DR. The DC power supply DC is electrically connected to the focus ring FR via the power supply line SP and to the conductive ring DR via the power supply line SQ. The DC power supply DC is configured to apply the same or different DC voltages to the focus ring FR and the conductive ring DR.

[0058] The DC power supply DC has either the configuration shown in FIG. 3 or the configuration shown in FIG. 4. The configuration of the DC power supply DC will be described with reference to FIGS. 3 and 4. First, the configuration of the DC power supply DC shown in FIG. 3 will be described. The DC power supply DC includes a filter FT1, a filter FT2, and a DC power supply DCS. The filter FT1 is electrically connected to the focus ring FR via a power feed line SP. The filter FT2 is electrically connected to the conductive ring DR via a power feed line SQ. The DC power supply DCS is electrically connected to the focus ring FR via the filter FT1 and the power feed line SP. The DC power supply DCS is electrically connected to the conductive ring DR via the filter FT2 and the power feed line SQ. The DC power supply DCS is configured to apply a common DC voltage to the focus ring FR and the conductive ring DR. The filters FT1 and FT2 are configured to block input of high frequency signals output from the first high frequency power supply 62 and the second high frequency power supply 64 to the DC power supply DCS. For example, filter FT1 blocks high-frequency waves input from focus ring FR via power supply line SP, and filter FT2 blocks high-frequency waves input from conductive ring DR via power supply line SQ. Filters FT1 and FT2 can reduce or eliminate the effects of high-frequency waves on DC power supply DCS. Controller MC is configured to control the DC voltage output from DC power supply DCS.

[0059] 3 has a configuration in which a common (same) DC voltage can be applied to the focus ring FR and the conductive ring DR from the DC power supply DC via the power supply line SP and the power supply line SQ, respectively. Therefore, the potential difference between the focus ring FR and the conductive ring DR is reduced by the DC voltage supplied via the power supply line SP and the power supply line SQ, respectively.

[0060] The application of a DC voltage when the plasma processing apparatus 1 includes a DC power supply DC having the configuration shown in FIG. 3 will be briefly described below. First, based on the inclination (inclination from a direction perpendicular to the substrate surface) of a groove formed at an edge of a substrate that has previously been subjected to an etching process, a DC voltage (DC voltage output from the DC power supply DCS) to be applied to the focus ring FR required to eliminate the inclination is obtained. For example, the correspondence between the inclination of the groove and the DC voltage output from the DC power supply DCS is previously established using a table or the like. When plasma processing is being performed (when high frequency power is being output from the first high frequency power supply 62 and the second high frequency power supply 64), the controller MC controls the DC power supply DCS to output the DC voltage obtained from the table or the like.

[0061] Next, the configuration of the DC power supply DC shown in FIG. 4 will be described. The DC power supply DC includes a DC power supply DCS1 and a DC power supply DCS2. The DC power supply DCS1 is electrically connected to the focus ring FR via a power supply line SP. The DC power supply DCS1 is configured to apply a DC voltage to the focus ring FR. The DC power supply DCS2 is electrically connected to the conductive ring DR via a power supply line SQ. The DC power supply DCS2 is configured to apply a DC voltage to the conductive ring DR. The DC power supplies DCS1 and DCS2 are configured to output DC voltages independently of each other. The controller MC is configured to control the DC voltages output from the DC power supplies DCS1 and DCS2. The controller MC controls the DC voltages output from the DC power supplies DCS1 and DCS2 so as to reduce the potential difference between the focus ring FR and the conductive ring DR. For example, the controller MC controls the DC voltages output from the DC power supplies DCS1 and DCS2 so as to equalize the potential of the focus ring FR and the potential of the conductive ring DR.

[0062] 4 has a configuration in which different DC voltages can be applied to the focus ring FR and the conductive ring DR from the DC power supply DC via the power supply lines SP and SQ, respectively. Therefore, the potential difference between the focus ring FR and the conductive ring DR is reduced or eliminated by the DC voltages supplied via the power supply lines SP and SQ, respectively.

[0063] The application of DC voltages when the plasma processing apparatus 1 includes a DC power supply DC having the configuration shown in FIG. 4 will be briefly described. First, based on the inclination (inclination from a direction perpendicular to the substrate surface) of a groove formed at the edge of a substrate that has previously been subjected to an etching process, a DC voltage required to eliminate the inclination is obtained. The obtained DC voltages are a DC voltage to be applied to the focus ring FR (a DC voltage output from the DC power supply DCS1) and a DC voltage to be applied to the conductive ring DR (a DC voltage output from the DC power supply DCS2). For example, a correspondence relationship between the inclination of the groove, the DC voltage output from the DC power supply DCS1, and the DC voltage output from the DC power supply DCS2 is previously established using a table or the like. When plasma processing is being performed (when high frequency waves are being output from the first high frequency power supply 62 and the second high frequency power supply 64), the controller MC controls the DC power supplies DCS1 and DCS2 to output the DC voltages obtained from the table or the like.

[0064] Returning to Fig. 2, the conductive ring DR is placed on the outer covering ring CRb. Because the outer covering ring CRb is thick, the conductive ring DR is not coupled to the first high frequency power supply 62 and the second high frequency power supply 64 as a high frequency circuit via the outer covering ring CRb.

[0065] The outer covering ring CRb has an inner upper surface SFc and an outer upper surface SFd. The inner side of the outer covering ring CRb is closer to the focus ring FR and therefore more easily worn than the outer side. Therefore, in the example of FIG. 2, the conductive ring DR is disposed so as to cover only the portion that is more easily worn (the inner upper surface SFc of the outer covering ring CRb). That is, the outer periphery OPd of the conductive ring DR is disposed inside the outer periphery OPe of the covering ring CR, and the outer upper surface of the covering ring CR is exposed to the plasma processing space (internal space 12c). The conductive ring DR may be disposed so as to cover the entire upper surface of the outer covering ring CRb. Also, in the example of FIG. 2, the outer upper surface SFd and the inner upper surface SFc covered by the conductive ring DR are configured to be coplanar, but they may be configured to be non-coplanar. For example, the upper surface SFd of the outer covering ring CRb that is not covered by the conductive ring DR may be higher than the upper surface SFb of the conductive ring DR or may be at the same height.

[0066] 2, a gap AS is provided between the focus ring FR and the conductive ring DR. More specifically, a first side surface SSa on the outer periphery OPc of the focus ring FR and a second side surface SSb on the inner periphery IPb of the conductive ring DR face each other and are spaced apart from each other. An inner circumferential lower surface ILSb of the conductive ring DR is located below an outer circumferential lower surface ILSa of the focus ring FR.

[0067] 2, the area of ​​the second side surface SSb is configured to be smaller than the area of ​​the top surface SFb of the conductive ring DR. The top surface SFb of the conductive ring DR is higher than the top surface of the focus ring FR. In other words, the thickness of the inner circumference IPb of the conductive ring DR is thicker than the thickness of the outer circumference OPc of the focus ring FR.

[0068] The distance GA between the first side surface SSa and the second side surface SSb is the width of the gap AS. As will be described later, the first side surface SSa and the second side surface SSb function as a capacitor. Therefore, the distance GA can be greater than zero and smaller than the thickness SH of the focus ring FR.

[0069] The cover ring CR further includes a separation portion DT that separates the first side surface SSa of the focus ring FR from the second side surface SSb of the conductive ring DR.

[0070] 2, the inner peripheral upper surface SFc of the outer covering CRb is configured lower than the upper surface SFa of the inner covering CRa, thereby providing a step between the inner covering CRa and the outer covering CRb, thereby forming the separation portion DT. Because the step abuts against the second side surface SSb of the conductive ring DR, the second side surface SSb of the conductive ring DR does not come into contact with the first side surface SSa of the focus ring FR. In other words, providing the separation portion DT can prevent the first side surface SSa and the second side surface SSb from coming into contact with each other, preventing the capacitor from functioning properly.

[0071] In the mounting table 16 configured as described above, the conductive ring DR is disposed on the cover ring CR. Because the thickness of the cover ring CR is greater than the thickness of the main body of the electrostatic chuck 20, the conductive ring DR is not coupled to the first and second RF power supplies 62 and 64 via the cover ring CR as a RF circuit. Furthermore, the first side surface SSa of the outer periphery OPc of the focus ring FR and the second side surface SSb of the inner periphery IPb of the conductive ring DR face each other and are spaced apart from each other. Therefore, the first and second side surfaces SSa and SSb function as a capacitor. That is, the focus ring FR and the conductive ring DR are capacitively coupled at the first and second side surfaces SSa and SSb. When RF power is applied to the base 18, electrostatic induction occurs inside the conductive ring DR due to positive or negative charges present on the first side surface SSa of the outer periphery OPc of the focus ring FR. Therefore, charges of equal and opposite magnitude to those collected on the second side surface SSb of the conductive ring DR are attracted by the plasma potential and collected on the upper surface SFb of the conductive ring DR. Because the area of ​​the top surface SFb is larger than the area of ​​the second side surface SSb, the amount of charge per unit area present on the top surface SFb is smaller than the amount of charge per unit area present on the second side surface SSb. Therefore, the potential of the conductive ring DR is lower than the potential of the focus ring FR, and the acceleration of ions in the plasma toward the conductive ring DR is reduced. As a result, the conductive ring DR (i.e., the region outside the focus ring FR) is less likely to be sputtered.

[0072] The conductive ring DR is arranged to cover the portions of the covering ring CR that are prone to wear, and is made of a material that is more resistant to sputtering than the covering ring CR. Furthermore, since the acceleration of ions toward the conductive ring DR is reduced, the conductive ring DR itself is less susceptible to sputtering. Therefore, wear of the covering ring CR around the outer periphery of the focus ring FR can be suppressed, thereby suppressing fluctuations in the area of ​​the focus ring FR as a cathode. This can suppress process fluctuations, such as tilting at the edge of the substrate.

[0073] Moreover, by adjusting the area of ​​the upper surface SFb of the conductive ring DR, the potential of the upper surface SFb of the conductive ring DR can be adjusted.

[0074] Furthermore, the conductive ring DR is disposed opposite the first side surface SSa of the focus ring FR. Because an object (the conductive ring DR) is present on the lateral side of the first side surface SSa of the focus ring FR, ions heading toward the first side surface SSa are blocked by the conductive ring DR. Therefore, the focus ring FR is less likely to be sputtered from the first side surface SSa, thereby suppressing wear of the focus ring FR.

[0075] In the example shown in FIG. 2, the substrate mounting portion 31a and the peripheral portion 31b on which the focus ring FR is mounted are configured with electrostatic chucks 20, but this is not limiting. The electrostatic chucks on the substrate mounting portion 31a and the peripheral portion 31b may be provided independently. Alternatively, as shown in FIG. 5, only the substrate mounting portion 31a may be configured with electrostatic chuck 20, and the peripheral portion 31b may be configured with base 18. Alternatively, the entire focus ring FR may be mounted on the peripheral portion 31b, not just the inner periphery thereof. The peripheral portion 31b may be formed lower than the substrate mounting portion 31a, forming a step.

[0076] In addition, as shown in the example of FIG. 2, the separation portion DT is formed by configuring the inner circumferential upper surface SFc of the outer covering ring CRb lower than the upper surface SFa of the inner covering ring CRa, but this is not limited to this. As shown in FIG. 6, a concave groove may be formed in the covering ring CR on which the conductive ring DR is mounted, and the inner circumferential lower surface ILSb of the conductive ring DR may be configured to be convex facing downward. In this case, the inner circumferential lower surface ILSb of the conductive ring DR is accommodated in the concave (groove) of the covering ring CR. By fitting the convex inner circumferential lower surface ILSb into the concave groove, the position of the conductive ring DR on the covering ring CR can be stably maintained. Note that, although a groove is formed in the outer covering ring CRb as the separation portion DT in FIG. 6, it may also be formed on the inner covering ring CRa. In this case, the inner circumferential side of the conductive ring DR is mounted on the inner covering ring CRa, and the outer circumferential side of the conductive ring DR is mounted on the outer covering ring CRb. 6, the top surface SFa of the covering ring CR on which the focus ring FR is mounted and the top surface SFc of the covering ring CR on which the conductive ring DR is mounted are configured to be at the same height, but they may be configured to be at different heights. For example, the top surface SFc of the covering ring CR on which the conductive ring DR is mounted may be configured to be higher than the top surface SFa of the covering ring CR on which the focus ring FR is mounted.

[0077] In the example shown in FIG. 2, the first side surface SSa of the focus ring FR and the second side surface SSb of the conductive ring DR are opposed to and spaced apart from each other to function as a capacitor, but this is not limiting. As shown in FIG. 7, the lower surface of the outer periphery of the focus ring FR and the upper surface of the inner periphery of the conductive ring DR may be opposed to and spaced apart from each other. In the conductive ring DR shown in FIG. 7, the lower part of the inner periphery protrudes toward the inner periphery. The upper surface of the protruding lower inner periphery of the conductive ring DR and the lower surface of the focus ring FR are opposed to and spaced apart from each other. In addition, the first side surface SSa of the focus ring FR and the second side surface SSb, which is the side surface of the upper inner periphery of the conductive ring DR, are opposed to and spaced apart from each other.

[0078] The inner circumferential upper surface SFc of the outer covering ring CRb is lower than the upper surface SFa of the inner covering ring CRa, forming a step portion serving as the separation portion DT between the inner covering ring CRa and the outer covering ring CRb. Because the third side surface SSc, which is the side surface of the lower inner circumferential portion of the conductive ring DR, abuts against the step portion (the outer circumferential side surface of the inner covering ring CRa), the second side surface SSb, which is the side surface of the upper inner circumferential portion of the conductive ring DR, does not come into contact with the first side surface SSa of the focus ring FR. Furthermore, the upper surface SFa of the inner covering ring CRa is formed at a position higher than the upper surface of the lower inner circumferential portion of the conductive ring DR. Therefore, because the lower surface of the focus ring FR abuts against the upper surface SFa of the inner covering ring CRa, the upper surface of the lower inner circumferential portion of the conductive ring DR does not come into contact with the lower surface of the focus ring.

[0079] 7, not only the first side surface SSa and the second side surface SSb but also the lower surface of the outer circumferential portion of the focus ring FR and the upper surface of the lower inner circumferential portion of the conductive ring DR can function as a capacitor, thereby increasing the capacitance between the focus ring FR and the conductive ring DR.

[0080] The distance GB between the lower surface of the outer periphery of the focus ring FR and the upper surface of the lower inner periphery of the conductive ring DR may be configured to be smaller than the distance GA between the first side surface SSa and the second side surface SSb. Because the distance GB is smaller than the distance GA, the capacitance between the lower surface of the outer periphery of the focus ring FR and the upper surface of the lower inner periphery of the conductive ring DR is greater than the capacitance between the first side surface SSa and the second side surface SSb. Therefore, even if the areas of the first side surface SSa and the second side surface SSb change due to wear of the focus ring FR and the conductive ring DR, the change in capacitance between the focus ring FR and the conductive ring DR can be reduced. Furthermore, because the distance GA between the first side surface SSa and the second side surface SSb can be increased, it is possible to prevent the gap AS from being blocked by deposits, preventing it from functioning as a capacitor (or causing large fluctuations in capacitance).

[0081] The area of ​​the upper surface of the lower inner periphery of the conductive ring DR, which faces the lower surface of the outer periphery of the focus ring FR, may be configured to be larger than the area of ​​the side surface of the inner periphery of the conductive ring DR, which faces the side surface of the outer periphery of the focus ring FR. This increases the capacitance between the lower surface of the outer periphery of the focus ring FR and the upper surface of the lower inner periphery of the conductive ring DR, thereby reducing fluctuations in capacitance between the focus ring FR and the conductive ring DR.

[0082] 7, a sloped portion may be formed between the inner peripheral side surface and the top surface of the conductive ring DR. By providing the sloped portion, the change in height between the top surface of the focus ring FR and the top surface of the conductive ring DR can be reduced, and the discontinuity of the sheath formed above the conductive ring DR and the focus ring FR can be reduced.

[0083] 2 to 7, the upper surface SFb of the conductive ring DR is configured to be higher than the upper surface of the focus ring FR, but this is not limiting. The upper surface SFb of the conductive ring DR may be configured to be flush with the upper surface of the focus ring FR, or may be configured to be lower than the upper surface of the focus ring FR.

[0084] 7, the lower surface of the outer periphery of the focus ring FR and the upper surface of the inner periphery of the conductive ring DR are opposed to and spaced apart from each other. Alternatively, as shown in FIG. 8, the upper surface of the outer periphery of the focus ring FR and the lower surface of the inner periphery of the conductive ring DR may be opposed to and spaced apart from each other.

[0085] 8, the upper part of the inner circumferential portion of the conductive ring DR protrudes inward. The lower surface of the protruding upper inner circumferential portion of the conductive ring DR and the upper surface of the focus ring FR face each other and are spaced apart. In addition, the first side surface SSa of the focus ring FR and the second side surface SSb, which is the side surface of the lower inner circumferential portion of the conductive ring DR, face each other and are spaced apart.

[0086] The inner circumferential upper surface SFc of the outer covering ring CRb is lower than the upper surface SFa of the inner covering ring CRa, forming a step portion serving as the separation portion DT between the inner covering ring CRa and the outer covering ring CRb. The second side surface SSb, which is the side surface of the lower inner circumferential portion of the conductive ring DR, abuts against the step portion (the outer circumferential side surface of the inner covering ring CRa), so the second side surface SSb, which is the side surface of the upper inner circumferential portion of the conductive ring DR, does not come into contact with the first side surface SSa of the focus ring FR. Furthermore, the lower surface of the protruding upper inner circumferential portion of the conductive ring DR is formed at a position higher than the upper surface of the outer circumferential portion of the focus ring. Therefore, the lower surface of the upper inner circumferential portion of the conductive ring DR does not come into contact with the upper surface of the focus ring.

[0087] 7, the distance GC between the outer peripheral upper surface of the focus ring FR and the upper inner peripheral lower surface of the conductive ring DR may be configured to be smaller than the distance GA between the first side surface SSa and the second side surface SSb. The area of ​​the upper inner peripheral lower surface of the conductive ring DR facing the outer peripheral upper surface of the focus ring FR may be larger than the area of ​​the inner peripheral side surface of the conductive ring DR facing the outer peripheral side surface of the focus ring FR.

[0088] As shown in the example of Figure 8, the gap AS is covered by the upper inner periphery of the conductive ring DR, which prevents the gap AS from being blocked by deposits and causing it to no longer function as a capacitor (or causing large fluctuations in capacitance).

[0089] 7 and 8, the lower surface (upper surface) of the outer periphery of the focus ring FR and the upper surface (lower surface) of the inner periphery of the conductive ring DR face each other and are spaced apart. Furthermore, the first side surface SSa of the focus ring FR and the second side surface SSb of the conductive ring DR face each other and are spaced apart. However, only the lower surface (upper surface) of the outer periphery of the focus ring FR and the upper surface (lower surface) of the inner periphery of the conductive ring DR may face each other and be spaced apart.

[0090] 2 to 8, the focus ring FR is disposed so that its outer circumferential side (outer circumferential portion) covers the inner covering ring CRa. However, the entire focus ring FR may be disposed on the electrostatic chuck 20 or the base 18. That is, not only the inner circumferential side (inner circumferential portion) of the focus ring FR but also the outer circumferential side (outer circumferential portion) may be mounted on the electrostatic chuck 20 or the base 18, which is the peripheral portion 31b of the mounting portion 31.

[0091] 9 shows an example in which only the upper surface of the outer periphery of the focus ring FR and the lower surface of the inner periphery of the conductive ring DR are opposed to and spaced apart from each other, and the entire focus ring FR is placed on an electrostatic chuck 20.

[0092] The inner periphery of the cover ring CR is mounted on the outer periphery of the focus ring FR. A conductive ring DR is mounted on the cover ring CR. The inner periphery of the conductive ring DR has a protrusion that protrudes downward, and the lower surface of the protrusion (the lower surface of the inner periphery) faces and is spaced apart from the upper surface of the outer periphery of the focus ring FR. Because the conductive ring DR is mounted on the cover ring CR, the upper surface of the cover ring CR and the lower surface of the outer periphery of the conductive ring DR abut against each other. In other words, the upper surface of the cover ring CR forms a separation portion DT, and the lower surface of the protrusion of the conductive ring DR does not contact the upper surface of the outer periphery of the focus ring FR. Note that, as shown in the example of FIG. 9, a protrusion that protrudes downward is formed on the inner periphery of the conductive ring DR. However, if sufficient capacitance can be obtained between the lower surface of the inner periphery of the conductive ring DR and the upper surface of the outer periphery of the focus ring FR, the protrusion need not be formed.

[0093] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various omissions, substitutions, and modifications may be made. Furthermore, elements in different exemplary embodiments may be combined to form other exemplary embodiments.

[0094] For example, a plasma processing apparatus 1 according to one exemplary embodiment includes a plurality of power feed lines SP and a plurality of power feed lines SQ. The focus ring FR has a shape extending along the peripheral edge portion 31b of the mounting table 16. The conductive ring DR has a shape extending to surround the focus ring FR. The plurality of power feed lines SP are arranged spaced apart from one another in the circumferential direction of the focus ring FR. The plurality of power feed lines SQ are arranged spaced apart from one another in the circumferential direction of the conductive ring DR.

[0095] A configuration in which a filter is provided for each of two independent DC power supplies is also possible. Specifically, the filters FT1 and FT2 of the DC power supply DC shown in FIG. 3, which has one DC power supply DCS, can also be applied to the DC power supply DC shown in FIG. 4, which has multiple DC power supplies (DC power supplies DCS1 and DCS2). In this case, the filter FT1 can be electrically connected to the focus ring FR via a power supply line SP, and the filter FT2 can be electrically connected to the conductive ring DR via a power supply line SQ. The DC power supply DCS1 can be electrically connected to the focus ring FR via the filter FT1 and the power supply line SP, and the DC power supply DCS2 can be electrically connected to the conductive ring DR via the filter FT2 and the power supply line SQ.

[0096] From the foregoing, it will be understood that various exemplary embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various exemplary embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0097] 1...plasma processing apparatus, 10...chamber, 16...mounting table, 20...electrostatic chuck, 20p...DC power supply, 31b...periphery, CR...covering, DC...DC power supply apparatus, DCS...DC power supply, DR...conductive ring, DT...separator, FR...focus ring, FT1...filter, FT2...filter, MC...controller, SP...power supply line, SQ...power supply line, W...substrate.

Claims

1. a mounting table having a substrate mounting portion on which a substrate is mounted and a peripheral portion surrounding the substrate mounting portion; a conductive focus ring placed on the peripheral portion of the mounting table; a cover ring made of a dielectric material and surrounding the outer periphery of the mounting table; a conductive ring placed on the cover ring; a high frequency power source coupled to the mounting table; a plurality of first power supply lines arranged spaced apart from one another in a circumferential direction of the focus ring and electrically connected to the focus ring; a plurality of second feed lines arranged spaced apart from one another in a circumferential direction of the conductive ring and electrically connected to the conductive ring; a first DC power supply electrically connected to the focus ring via the plurality of first power supply lines; a second DC power supply electrically connected to the conductive ring via the plurality of second power supply lines and configured to apply a DC voltage to the conductive ring that is different from the DC voltage applied to the focus ring from the first DC power supply; a control unit configured to control the DC voltages output from the first DC power supply and the second DC power supply; Equipped with a first surface on an outer periphery of the focus ring and a second surface on an inner periphery of the conductive ring are opposed to and spaced apart from each other; the cover ring has a separation portion that separates the focus ring and the conductive ring, the control unit controls the DC voltages output from the first DC power supply and the second DC power supply so as to reduce a potential difference between the focus ring and the conductive ring. Plasma processing equipment.

2. an inner peripheral portion of the focus ring is supported by the peripheral edge portion of the mounting table, and the outer peripheral portion of the focus ring covers an upper surface of the inner peripheral portion of the cover ring; The plasma processing apparatus according to claim 1 .

3. the focus ring and the conductive ring are capacitively coupled at the first surface and the second surface.

3. The plasma processing apparatus according to claim 1 or 2.

4. a distance between the first surface and the second surface is greater than zero and less than a thickness of the focus ring; The plasma processing apparatus according to any one of claims 1 to 3.

5. a lower surface of an inner periphery of the conductive ring is located lower than a lower surface of an outer periphery of the focus ring; The plasma processing apparatus according to any one of claims 1 to 4.

6. the separating portion is configured to abut against a side surface of an inner circumferential portion of the conductive ring, and is a stepped portion formed on a surface of the cover ring. The plasma processing apparatus according to any one of claims 1 to 5.

7. the separation portion is a groove portion formed on the surface of the cover ring, The lower surface of the inner periphery of the conductive ring is accommodated in the groove. The plasma processing apparatus according to any one of claims 1 to 5.

8. the first surface is a side surface of an outer periphery of the focus ring, and the second surface is a side surface of an inner periphery of the conductive ring. The plasma processing apparatus according to any one of claims 1 to 7.

9. the first surface is a lower surface of an outer periphery of the focus ring, and the second surface is an upper surface of an inner periphery of the conductive ring; The plasma processing apparatus according to any one of claims 1 to 6.

10. an outer peripheral side surface of the focus ring and an inner peripheral side surface of the conductive ring are opposed to and spaced apart from each other; The plasma processing apparatus according to any one of claims 1 to 8.

11. an area of ​​an upper surface of an inner periphery of the conductive ring facing a lower surface of an outer periphery of the focus ring is larger than an area of ​​a side surface of the inner periphery of the conductive ring facing a side surface of the outer periphery of the focus ring; 10. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is a plasma processing apparatus.

12. a gap between a lower surface of an outer periphery of the focus ring and an upper surface of an inner periphery of the conductive ring is narrower than a gap between a side surface of the outer periphery of the focus ring and a side surface of the inner periphery of the conductive ring; The plasma processing apparatus according to any one of claims 1 to 6, 9 and 11.

13. the first surface is an upper surface of an outer periphery of the focus ring, and the second surface is a lower surface of an inner periphery of the conductive ring; The plasma processing apparatus according to any one of claims 1 to 4.

14. a first filter electrically connected to the focus ring via the first power supply line; a second filter electrically connected to the conductive ring via the second feed line; Further provided with the first DC power supply is electrically connected to the focus ring via the first filter and the first power supply line; the second DC power supply is electrically connected to the conductive ring via the second filter and the second power supply line; the first filter and the second filter are configured to block input of a high frequency wave output from the high frequency power supply to the first DC power supply and the second DC power supply. The plasma processing apparatus according to any one of claims 1 to 13.

15. the control unit controls the DC voltages output from the first DC power supply and the second DC power supply so as to equalize a potential of the focus ring and a potential of the conductive ring. The plasma processing apparatus according to any one of claims 1 to 14.

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