Etching device

Abstract

Provided is a technology capable of applying a bias potential to a support part. This etching device comprises a mount part (20), a potential application member (30), a raising / lowering drive unit (40), a plasma generator (50), and a heating unit (80). A transportable support part (21) supporting a substrate (W) is mounted on the mount part (20). The heating unit (80) includes a light source (81) that is located below the mount part (20) and produces a heating light to heat the substrate (W). The potential application member (30) is provided above the mount part (20), and a prescribed bias potential is applied thereto. The raising / lowering drive unit (40) raises and lowers the mount part (20) between an upper position, where the potential application member (30) is in contact with the substrate (W) or the support part (21), and a lower position, where the potential application member (30) is separated from the substrate (W) and the support part (21). The plasma generator (50) generates a plasma, supplies the plasma to the upper surface of the substrate (W) on the support part (21) mounted on the mount part (20), and etches the upper surface of the substrate (W) by means of the plasma.

Description

Etching equipment

[0001] The present disclosure relates to an etching apparatus.

[0002] Apparatuses for etching Group III nitride semiconductors have been proposed in the past (e.g., Patent Documents 1 and 2). In Patent Documents 1 and 2, the etching apparatus heats a substrate while generating a chlorine-based gas containing chlorine into plasma and supplies the plasma to the substrate. Ions and radicals in the plasma act on the substrate, thereby etching the Group III nitride semiconductor on the substrate.

[0003] Furthermore, in conventional plasma devices, a substrate is placed on a placement section on which a base material to which a bias potential is applied is placed together with a heater-integrated electrostatic chuck (see, for example, Patent Document 3).

[0004] JP 2020-80349 A JP 2018-152415 A JP 2009-170509 A

[0005] In the case of a mounting section that includes both an electrostatic chuck with a built-in heater and a substrate to which a bias potential is applied, a design that suppresses interference of electric fields is required, resulting in a complex mechanism.

[0006] Meanwhile, a support part supporting a substrate may be transported into a chamber of an etching apparatus. Inside the chamber, the support part is placed on a mounting part. When a bias potential is applied to the mounting part inside the chamber, an electric field resulting from the bias potential can be generated in the space above the substrate. This allows ions of the plasma above the substrate to move toward the substrate. However, heating by an electric resistance heater can cause thermal expansion of the mounting part's components, which can lead to warping of the mounting part's components. Furthermore, processing using corrosive gases at high temperatures using an electric resistance heater can cause deformation of the mounting part's components due to electrical discharge corrosion. When the mounting part's components warp or deform, the formation of an electric field in the space above the substrate becomes unstable.

[0007] Therefore, an object of the present disclosure is to provide a technique capable of forming a stable electric field in the space above a substrate.

[0008] A first aspect is an etching apparatus comprising: a mounting section on which a portable support section supporting a substrate is placed; a heating section located below the mounting section and including a light source that emits heating light to heat the substrate; a potential application member located above the mounting section and to which a predetermined bias potential is applied; an elevation drive section that raises and lowers the mounting section between an upper position where the potential application member contacts the substrate or the support section and a lower position where the potential application member is spaced apart from the substrate and the support section; and a plasma generator that generates plasma, supplies the plasma to an upper surface of the substrate on the support section placed on the mounting section, and etches the upper surface of the substrate with the plasma.

[0009] A second aspect is the etching apparatus according to the first aspect, wherein the mounting portion is translucent to the light.

[0010] A third aspect is the etching apparatus according to the second aspect, wherein, in the upper position, the potential application member contacts the upper surface of the substrate.

[0011] A fourth aspect is an etching apparatus according to any one of the first to third aspects, comprising a chamber, the chamber including a cylindrical portion that houses the potential application member and the placement portion, and an entry portion that is connected to a portion of the side wall of the cylindrical portion that is lower than the potential application member and through which the substrate and the support portion pass.

[0012] A fifth aspect is the etching apparatus according to any one of the first to fourth aspects, wherein the potential application member includes conductive carbon and a silicon carbide film formed on a surface of the conductive carbon.

[0013] A sixth aspect is the etching apparatus according to any one of the first to fifth aspects, wherein the potential application member includes a circular member having a circular ring shape in a plan view.

[0014] According to the first aspect, a stable electric field can be formed in the space above the substrate.

[0015] According to the second aspect, the light from the light source passes through the mounting portion and enters the support portion, which allows the support portion, which is closer to the substrate, to be heated, thereby improving the heating efficiency for the substrate.

[0016] According to the third aspect, the potential application member can press the substrate toward the support portion, thereby improving the adhesion between the lower surface of the substrate and the upper surface of the support portion, thereby more effectively transferring heat from the support portion to the substrate.

[0017] According to the fourth aspect, the portion of the inner circumferential surface of the cylindrical portion above the substrate can be formed into a cylindrical shape. This makes it possible to make the flow of plasma in the space above the substrate uniform. This allows the plasma to act more uniformly on the upper surface of the substrate.

[0018] According to the fifth aspect, the reliability of the potential application member can be improved.

[0019] According to the sixth aspect, the flow of plasma in the space above the substrate can be made more uniform, so that the plasma can act more uniformly on the upper surface of the substrate.

[0020] FIG. 1 is a diagram schematically showing an example of the configuration of an etching apparatus; FIG. 2 is a top view schematically showing an example of the configuration of a chamber; FIG. 3 is a perspective view schematically showing an example of the configuration of a circular ring member; FIG. 4 is a diagram schematically showing an example of the configuration of an etching apparatus; and FIG. 5 is a diagram schematically showing an example of the configuration of an etching apparatus.

[0021] Hereinafter, the embodiments will be described in detail with reference to the drawings. In the drawings, the dimensions and numbers of each part are exaggerated or simplified as necessary for ease of understanding. Parts having similar configurations and functions are assigned the same reference numerals, and duplicate explanations will be omitted below.

[0022] In the following description, the same components are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed descriptions of them may be omitted to avoid duplication.

[0023] Furthermore, in the following description, even if ordinal numbers such as "first" or "second" are used, these terms are used for convenience to facilitate understanding of the contents of the embodiments, and are not limited to the ordering that may result from these ordinal numbers.

[0024] When expressions indicating relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) are used, unless otherwise specified, the expressions not only strictly represent the positional relationship but also represent a state in which there is a relative displacement in terms of angle or distance within a range in which tolerance or equivalent functionality is obtained. When expressions indicating an equal state (e.g., "identical," "equal," "homogeneous," etc.) are used, the expressions not only represent a state in which there is strict quantitative equality but also represent a state in which there is a difference in which tolerance or equivalent functionality is obtained, unless otherwise specified. When expressions indicating a shape (e.g., "rectangular shape" or "cylindrical shape," etc.) are used, the expressions not only represent a geometrically strict shape but also represent a shape with, for example, irregularities or chamfers within a range in which equivalent effects are obtained. When the expressions "comprise," "include," "have," "includes," "includes," or "have" are used to describe one component, the expressions are not exclusive expressions that exclude the presence of other components. When the phrase "at least one of A, B, and C" is used, the phrase includes A only, B only, C only, any two of A, B, and C, and all of A, B, and C.

[0025] <Etching Apparatus> FIG. 1 is a diagram schematically illustrating an example of the configuration of an etching apparatus 1. The etching apparatus 1 performs etching on a substrate W. A group III nitride semiconductor film, which is an etching target, is formed on the upper surface of the substrate W. As the group III nitride semiconductor, for example, a gallium nitride (GaN) semiconductor is applied. Gallium nitride semiconductors can be used in devices such as power devices, high-frequency devices, and optical devices. The gallium nitride semiconductor film can be formed on, for example, a silicon (Si) substrate or a silicon carbide (SiC) substrate. On the upper surface of the substrate W, a resist having a predetermined pattern may be formed on the group III nitride semiconductor film. The substrate W has, for example, a circular shape in a plan view.

[0026] The etching apparatus 1 includes a mounting unit 20 , a potential application member 30 , a lifting / lowering drive unit 40 , a plasma generator 50 , a heating unit 80 , and a control unit 90 .

[0027] As shown in FIG. 1 , the etching apparatus 1 may be provided with a chamber 10. The chamber 10 is a housing that forms a processing chamber in which etching is performed on a substrate W. The internal space surrounded by the inner circumferential surface of the chamber 10 corresponds to the processing chamber. FIG. 2 is a top view schematically illustrating an example of the configuration of the chamber 10. In the example of FIGS. 1 and 2 , the chamber 10 includes a cylindrical section 11 and a loading section 12. The cylindrical section 11 has a cylindrical shape with both ends closed. Specifically, the cylindrical section 11 includes a ceiling section that is circular in plan view, a floor section that is circular in plan view, and a cylindrical sidewall section that connects the periphery of the ceiling section to the periphery of the floor section. The loading section 12 is connected to the sidewall section of the cylindrical section 11 and has a substantially rectangular box shape. The internal space of the loading section 12 is connected to the internal space of the cylindrical section 11. Inside the loading section 12, the substrate W and the support section 21 are transported by a transport robot, as described below. The loading section 12 is provided with a shutter (not shown) that can be opened and closed. The loading section 12 may be a gate valve. The processing chamber mainly corresponds to the internal space of the cylindrical section 11. As shown in FIG. 1, the chamber 10 is conductive and can be grounded.

[0028] In the example of FIG. 1 , a pressure reducing unit 70 is connected to the chamber 10. The pressure reducing unit 70 is a device that reduces the pressure inside the chamber 10. The pressure reducing unit 70 includes an exhaust pipe 71 and a suction drive unit 72. The upstream end of the exhaust pipe 71 is connected to the chamber 10. For example, the upstream end of the exhaust pipe 71 is connected to a sidewall of the chamber 10. Note that the upstream ends of the multiple exhaust pipes 71 may be connected to the sidewall of the chamber 10 at positions that are equally spaced circumferentially. The suction drive unit 72 is provided on the exhaust pipe 71. The suction drive unit 72 includes, for example, a vacuum pump. The suction drive unit 72 sucks gas from the chamber 10 through the exhaust pipe 71. This reduces the pressure inside the chamber 10. The suction drive unit 72 is controlled by a control unit 90. A pressure sensor that measures the pressure inside the chamber 10 may be provided. The control unit 90 may control the suction drive unit 72 so that the pressure measured by the pressure sensor falls within a predetermined pressure range.

[0029] The mounting part 20 is provided in the chamber 10. As described below, a support part 21 is placed on the upper surface of the mounting part 20. The upper surface of the mounting part 20 may be a horizontal flat surface. The mounting part 20 has, for example, a circular shape in a plan view.

[0030] The support portion 21 has, for example, a plate-like shape. The support portion 21 is placed on the mounting portion 20 in a horizontal position with its thickness direction aligned with the vertical direction. The support portion 21 supports the substrate W in a horizontal position with the thickness direction of the substrate W aligned with the vertical direction. The upper surface of the support portion 21 may be a horizontal, flat surface. The upper surface of the support portion 21 is in contact with the lower surface of the substrate W. The support portion 21 may be wider than the substrate W in a planar view. That is, the periphery 21a of the support portion 21 may be located outside the periphery of the substrate W in a planar view. The support portion 21 has, for example, a circular shape in a planar view. In this case, the diameter of the support portion 21 may be larger than the diameter of the substrate W. The support portion 21 may be provided with a holding mechanism for holding the substrate W.

[0031] The support portion 21 is electrically conductive. The support portion 21 may be made of, for example, a metal material or conductive carbon. A silicon carbide (SiC) film may be formed on the surface of the support portion 21.

[0032] The support part 21 is transported together with the substrate W. That is, a transport robot external to the etching apparatus 1 transports the support part 21 supporting the substrate W. The transport robot transports the unprocessed substrate W and the support part 21 together into the chamber 10. Specifically, the transport robot transports the substrate W and the support part 21 into the cylindrical part 11 through the inside of the load part 12 and places the support part 21 on the platform 20. The etching apparatus 1 performs etching on the substrate W, as described below. The transport robot transports the processed substrate W and the support part 21 together from the chamber 10. Specifically, the transport robot takes out the substrate W and the support part 21 from the platform 20 and transports them out through the inside of the load part 12. Such a support part 21 can also be considered a portable support part. The support part 21 can also be called a susceptor. On the other hand, the platform 20 can also be considered a stationary platform installed in the etching apparatus 1.

[0033] 1 , the mounting part 20 is the upper part of a storage member 82 that houses the heating part 80. Specifically, the mounting part 20 is a plate-shaped portion at the top of the storage member 82. The storage member 82 includes the plate-shaped mounting part 20 and a cylindrical side wall part 821 that extends vertically downward from the periphery of the mounting part 20. The internal space of the storage member 82 may be isolated from the processing chamber in the chamber 10. The side wall part 821 may be connected to the floor of the chamber 10 via a bellows (not shown), for example.

[0034] The heating unit 80 includes a light source 81. The light source 81 is provided inside the storage member 82. The light source 81 is provided at a position vertically opposite to the placement unit 20, and emits light for heating. The light for heating may be, for example, infrared light. The light source 81 may be, for example, a halogen lamp. As shown in FIG. 1 , a plurality of light sources 81 may be provided. The plurality of light sources 81 may be lined up in the horizontal direction inside the storage member 82.

[0035] The mounting portion 20 may be translucent to the light emitted by the light source 81. The transmittance of the mounting portion 20 to the light may be, for example, 60% or more, 80% or more, or 95% or more. The mounting portion 20 may be formed of, for example, quartz glass. The mounting portion 20 may also be insulating. If the mounting portion 20 contains a conductive material, the transmittance of the mounting portion 20 will decrease. However, by employing an insulating mounting portion 20, the transmittance of the mounting portion 20 can be easily increased.

[0036] Light emitted by the light source 81 passes through the mounting part 20 and is absorbed by at least one of the support part 21 and the substrate W. This heats the substrate W. As a specific example, the absorptivity of the support part 21 for the light is higher than the absorptivity of the mounting part 20 for the light. In this case, at least a portion of the light emitted by the light source 81 is absorbed by the support part 21. This heats the support part 21, and the heat of the support part 21 is transferred to the substrate W, increasing the temperature of the substrate W. This increase in the temperature of the substrate W can improve the etching rate of the group III nitride semiconductor film on the substrate W. In other words, the light source 81 emits light so that the temperature of the substrate W falls within a predetermined temperature range suitable for etching. This shortens the time the substrate W is exposed to plasma, which will be described later, and reduces damage to the substrate W caused by the plasma, which will be described later.

[0037] In the example of FIG. 1 , a reflecting portion 83 is provided inside the storage member 82. The reflecting portion 83 is provided on the opposite side of the light source 81 from the mounting portion 20 (vertically downward in this case). The reflecting portion 83 is reflective to the light emitted by the light source 81. The reflecting portion 83 may be formed of a metal such as aluminum. The reflectance of the reflecting portion 83 with respect to the light may be, for example, 60% or more, 80% or more, or 95% or more. Light from the light source 81 toward the reflecting portion 83 is reflected by the reflecting portion 83 and travels toward the mounting portion 20. This increases the amount of light traveling toward the mounting portion 20, thereby improving heating efficiency.

[0038] The potential application member 30 is a member for applying a bias potential to the support part 21 or the substrate W. The potential application member 30 is conductive. The potential application member 30 may be made of, for example, conductive carbon, or may have a silicon carbide film formed on the surface of the conductive carbon.

[0039] In the example of FIG. 1 , the potential application member 30 includes a conductive circular member 31 and conductive support columns 32. FIG. 3 is a perspective view schematically illustrating an example of the configuration of the circular member 31. The circular member 31 has a plate-like shape and is circular in a plan view. In the example of FIG. 1 , the circular member 31 is provided vertically above the mounting unit 20. An inner peripheral edge 31 a of the circular member 31 is located inside the peripheral edge 21 a of the support unit 21 in a plan view, and an outer peripheral edge 31 b of the circular member 31 is located outside the peripheral edge 21 a of the support unit 21 in a plan view. In other words, the inner diameter (diameter) of the circular member 31 is smaller than the diameter of the support unit 21, and the outer diameter (diameter) of the circular member 31 is larger than the diameter of the support unit 21. In the example of FIG. 1 , the inner peripheral edge 31 a of the circular member 31 is located outside the peripheral edge of the substrate W. In other words, the inner diameter (diameter) of the circular member 31 is larger than the diameter of the substrate W.

[0040] As shown in Figures 1 and 3, the circular member 31 may be inclined downward as it goes inward. The circular member 31 may be rotationally symmetrical with respect to an imaginary axis that passes through the center of the substrate W and extends in the vertical direction. In the example of Figures 1 and 3, the circular member 31 has a plate-like shape that follows the side surface of a truncated cone. In this shape, the diameter of the circular member 31 in a horizontal cross section becomes wider as it goes vertically upward. The upper surface of the circular member 31 may be flat.

[0041] The support pillar 32 has a rod-like shape extending in the vertical direction, and the upper end of the support pillar 32 is connected to the annular member 31, and the lower end of the support pillar 32 is connected to, for example, the floor surface of the chamber 10. The upper end of the support pillar 32 is connected to, for example, the lower surface of the annular member 31. The support pillar 32 is located outside the storage member 82, and supports the annular member 31. The support pillar 32 is electrically connected to a power supply unit 60, which will be described later.

[0042] The circular member 31 may be supported not only by the support columns 32 but also by the support columns 33. More specifically, one or more support columns 32 and one or more support columns 33 may be provided. The support columns 33 have a rod-like shape extending along the vertical direction and are provided at positions different from the support columns 32 in a plan view. For example, the support columns 32 and 33 are provided at intervals so as to surround the support unit 21 and the storage member 82. The upper end of the support column 33 is connected to the circular member 31, and the lower end of the support column 33 is connected to the floor of the chamber 10. The support columns 33 may be insulating. Note that the support columns 32 and 33 are each provided at a position that avoids the transport path of the substrate W and the support unit 21.

[0043] A bias power supply unit 60 is electrically connected to the potential application member 30. The power supply unit 60 includes, for example, a matching circuit 61 and a high-frequency power supply 62. The matching circuit 61 is connected in series to the potential application member 30 and the high-frequency power supply 62. The matching circuit 61 is a circuit that matches the power supply impedance with the load impedance. One end of the high-frequency power supply 62 is electrically connected to the potential application member 30 (e.g., the support column 32) through the matching circuit 61, and the other end of the high-frequency power supply 62 is electrically grounded. The high-frequency power supply 62 applies a high-frequency voltage (bias potential) between the potential application member 30 and the ground through the matching circuit 61. The frequency of the bias potential is, for example, 2 MHz.

[0044] The lifting drive unit 40 lifts and lowers the mounting unit 20 between an upper position and a lower position. Fig. 4 is a diagram schematically showing an example of the configuration of the etching apparatus 1. Fig. 1 shows the etching apparatus 1 in a state where the mounting unit 20 is located in the lower position, and Fig. 4 shows the etching apparatus 1 in a state where the mounting unit 20 is located in the upper position.

[0045] The upper position is a position where at least one of the support part 21 and the substrate W (the support part 21 in FIG. 4 ) is in contact with the potential application member 30. Therefore, the potential application member 30 is electrically connected to the support part 21. With the potential application member 30 in contact with the support part 21, a bias potential can be applied to the support part 21. As shown in FIG. 1 , the lower position is a position vertically lower than the upper position, where both the support part 21 and the substrate W are separated from the potential application member 30. With the platform 20 in the lower position, the substrate W and the support part 21 are taken out of the platform 20 or transferred to the platform 20 by a transfer robot outside the chamber 10.

[0046] The lifting drive unit 40 includes, for example, a drive source such as a motor and a power conversion unit such as a ball screw mechanism, etc. Alternatively, the lifting drive unit 40 may include an air cylinder.

[0047] 1 , the upper part of the loading section 12 is located vertically below the circular member 31. The internal space of the loading section 12 is horizontally connected to the space between the circular member 31 and the platform 20 located at the lower position. The transport robot moves the substrate W and the support section 21 horizontally through the internal space of the loading section 12, and moves the substrate W and the support section 21 to directly above the platform 20. The transport robot then places the support section 21 on the platform 20.

[0048] When the lifting / lowering drive unit 40 moves the substrate W, the support unit 21, and the mounting unit 20 together to the upper position, the inner periphery of the potential application member 30 (e.g., the lower end of the inner periphery 31 a) comes into contact with the upper surface of the support unit 21. In this state, the power supply unit 60 applies a bias potential to the potential application member 30, thereby applying a bias potential to the support unit 21.

[0049] The plasma generator 50 is provided vertically above the substrate W on the support 21 placed on the mounting part 20. The plasma generator 50 is provided at a position vertically facing the substrate W. In the examples of FIGS. 1 and 4, the plasma generator 50 is provided on the ceiling of the chamber 10. The plasma generator 50 may be, for example, a capacitively coupled plasma type, an inductively coupled plasma type, a microwave plasma type, an electron cyclotron resonance plasma (ECR) type, a helicon wave excited plasma (HWP) type, or a microwave excited surface wave plasma (SWP) type. In the examples of FIGS. 1 and 4, the plasma generator 50 is an inductively coupled plasma type, and includes an inductively coupled antenna 51 and a plasma power supply unit 52.

[0050] The inductive coupling antenna 51 is formed of a conductive material. For example, the inductive coupling antenna 51 has a U-shaped rod shape. The inductive coupling antenna 51 is provided on the ceiling of the chamber 10 with both ends of the U-shape positioned vertically upward. The inductive coupling antenna 51 may also be embedded in the ceiling of the chamber 10. In the examples of FIGS. 1 and 4 , multiple inductive coupling antennas 51 are provided. A power supply unit 52 is electrically connected to the inductive coupling antenna 51. The power supply unit 52 applies a plasma voltage (e.g., a high-frequency voltage) to both ends of the inductive coupling antenna 51, thereby generating an electric field for plasma around the inductive coupling antenna 51. For example, the power supply unit 52 includes a matching circuit 521 and a high-frequency power supply 522. The matching circuit 521 is connected in series to the high-frequency power supply 522 and the inductive coupling antenna 51. The matching circuit 521 is a circuit that matches the source impedance and the load impedance. One end of the high-frequency power supply 522 is electrically connected to one end of the inductively coupled antenna 51 through a matching circuit 521, and the other end of the high-frequency power supply 522 is electrically connected to the other end of the inductively coupled antenna 51 and is also grounded. The high-frequency power supply 522 applies a high-frequency voltage to the inductively coupled antenna 51 through the matching circuit 521. The frequency of the high-frequency voltage is, for example, 13.56 MHz.

[0051] 1 and 4, a gas flow path 53a is formed so as to be surrounded by a plurality of inductively coupled antennas 51. The gas flow path 53a is formed by, for example, a gas pipe 53. The internal flow path of the gas pipe 53 corresponds to the gas flow path 53a. The gas pipe 53 extends in the vertical direction, and the inductively coupled antennas 51 are provided around the gas pipe 53. The lower end of the gas pipe 53 opens in the chamber 10. In other words, the lower end of the gas pipe 53 corresponds to the outlet of the gas flow path 53a. The upstream end of the gas pipe 53 is connected to a gas supply source 54. The gas supply source 54 includes a reservoir for storing gas and a valve. The gas supply source 54 supplies, for example, a chlorine-based gas containing chlorine (Cl) element to the upstream end of the gas pipe 53. The chlorine-based gas may be, for example, chlorine (Cl ２ ) gas, and chlorine gas and boron chloride (BCl ３ The gas supply source may supply a mixed gas containing at least one of hydrogen gas, nitrogen gas, and a rare gas together with the chlorine-based gas to the gas pipe 53.

[0052] The electric field generated by the inductively coupled antenna 51 acts on the gas in the gas pipe 53, converting the gas into plasma. This generates, for example, chlorine ions and chlorine radicals. These ions and radicals flow into the chamber 10 from the outlet of the gas pipe 53 and flow toward the substrate W. The ions and radicals act on the upper surface of the substrate W, etching the group III nitride semiconductor film on the upper surface of the substrate W.

[0053] The control unit 90 comprehensively controls the etching apparatus 1. Specifically, the control unit 90 controls the shutter of the chamber 10, the lifting / lowering drive unit 40, the plasma generator 50, the power supply unit 60, and the pressure reducing unit 70. The control unit 90 is an electronic circuit, and includes, for example, a data processing unit and a memory unit. The data processing unit and the memory unit are interconnected, for example, via a bus. The data processing unit may be, for example, an arithmetic processing device such as a central processing unit (CPU). The memory unit may include a non-transitory memory unit (e.g., a read-only memory (ROM)) and a temporary memory unit (e.g., a random access memory (RAM)). The non-transitory memory unit may store, for example, a program that defines the processing to be performed by the control unit 90. The data processing unit executes this program, allowing the control unit 90 to perform the processing defined in the program. Of course, some or all of the processing performed by the control unit 90 may be performed by hardware such as a dedicated logic circuit.

[0054] <Example of Operation of Etching Apparatus> Next, an outline of an example of operation of the etching apparatus 1 will be described. The operation of this etching apparatus 1 is realized by the control of the control unit 90.

[0055] First, with the lifting drive unit 40 stopping the mounting unit 20 at the lower position, the transport robot loads the substrate W and the support unit 21 into the chamber 10. Specifically, the support unit 21 supporting the substrate W is moved by the transport robot through the internal space of the loading unit 12 and placed on the mounting unit 20. Next, the control unit 90 closes the shutter of the loading unit 12 and controls the pressure reducing unit 70 to reduce the pressure in the chamber 10 to within a predetermined pressure range. The control unit 90 also controls the lifting drive unit 40 to raise the mounting unit 20 from the lower position to the upper position. This brings the potential application member 30 into contact with the support unit 21. The control unit 90 then controls the power supply unit 60 to apply a bias potential to the potential application member 30 and the support unit 21. The control unit 90 also controls the light source 81 to emit light for heating. This heats the substrate W.

[0056] Next, the control unit 90 controls the plasma generator 50 to generate plasma. Specifically, the gas supply source 54 supplies a gas containing a chlorine-based gas into the chamber 10 through the gas pipe 53, and the power supply unit 52 supplies high-frequency power to the inductively coupled antenna 51. As a result, an electric field generated around the inductively coupled antenna 51 acts on the gas in the gas pipe 53, converting the gas into plasma.

[0057] The ions and radicals generated by the plasma generation flow into the chamber 10 from the outlet of the gas pipe 53. The ions move toward the support 21 in response to the electric field caused by the bias potential of the support 21. As a result, many ions reach the upper surface of the substrate W. On the other hand, the force of the electric field does not act on the radicals, and therefore, although the directionality of the radical movement is not as high as that of the ions, they can reach the upper surface of the substrate W, for example, by following the airflow. The ions and radicals that reach the upper surface of the substrate W act on the Group III nitride semiconductor film, etching the Group III nitride semiconductor film.

[0058] In the above example, since the substrate W is heated by the light source 81, the etching rate by ions and radicals can be improved. Therefore, the time required for etching can be shortened. In other words, the time during which the substrate W is exposed to plasma is shortened, and therefore damage to the substrate W caused by plasma can be reduced.

[0059] When the group III nitride semiconductor film of the substrate W has been sufficiently etched (for example, when a predetermined etching time has elapsed), the control unit 90 terminates the etching. Specifically, the control unit 90 stops the operation of the power supply unit 60 and the plasma generator 50, and causes the lifting drive unit 40 to lower the mounting unit 20 to the lower position. This separates the support unit 21 from the potential application member 30, making it possible for the transfer robot to remove it. The control unit 90 also stops the operation of the pressure reducing unit 70. The transfer robot then carries the support unit 21, which is supporting the processed substrate W, out of the chamber 10.

[0060] As described above, the etching apparatus 1 can etch a group III nitride semiconductor film on the substrate W. Moreover, in the above example, the lifting driver 40 raises the mounting unit 20 to the upper position, thereby bringing the potential application member 30 into contact with the portable support 21 and applying a bias potential to the portable support 21. This allows the bias potential to be applied to the support 21, which is closer to the substrate W. In other words, compared to a comparative structure in which a bias potential is applied to the conductive mounting unit 20, the potential application member 30 can apply a bias voltage directly to the support 21, which is closer to the substrate W. This makes it possible to more effectively generate an electric field in the space above the substrate W that directs ions toward the substrate W. This allows ions in the plasma to be effectively moved to the upper surface of the substrate W.

[0061] In the above example, the stationary mounting part 20 in the chamber 10 is translucent to the light from the light source 81. Furthermore, since the mounting part 20 is insulating, the transmittance of the mounting part 20 to the light can be increased. This allows a greater amount of light from the light source 81 to be incident on the support part 21, thereby improving the heating efficiency of the support part 21. In this way, the light source 81 can heat the support part 21 that is closer to the substrate W.

[0062] As a comparative example, consider a structure in which light is absorbed by the mount 20. In this structure, heat is generated in the mount 20 and transferred to the substrate W via the support 21. In this structure, heat is transferred to the substrate W via the support 21, so the heating efficiency of the substrate W is relatively low. Furthermore, since the mount 20 itself becomes hot, the support 21 is likely to thermally deform when the substrate W and support 21 are placed on the high-temperature mount 20. In contrast, in this embodiment, light is transmitted through the mount 20 and absorbed by the support 21. Therefore, heat generated in the support 21 is transferred directly to the substrate W. This increases the heating efficiency of the substrate W. Furthermore, it is possible to suppress a temperature rise in the mount 20 and thermal deformation of the support 21.

[0063] As described above, the etching apparatus 1 can improve the heating efficiency of the support portion 21 and simultaneously apply a bias potential to the support portion 21 .

[0064] Furthermore, in the above example, the substrate W is heated by the light source 81. Therefore, compared to a structure using an electric resistance heater, the occurrence of unwanted discharge can be suppressed. Here, as a comparative example, consider a structure in which the mounting unit 20 is an electric resistance heater. In this structure, for example, unwanted discharge may occur due to an electric field between the support unit 21 to which a bias potential is applied and a heating wire in the mounting unit 20. If such discharge occurs, discharge corrosion may occur in the support unit 21 or the mounting unit 20. In contrast, in the above example, the substrate W is heated by the light source 81, so the occurrence of such discharge corrosion can be suppressed or prevented. Consequently, deformation of the support unit 21 and the mounting unit 20 due to discharge corrosion can be suppressed or prevented, and a stable electric field can be formed in the space above the substrate W.

[0065] Furthermore, in this embodiment, there is no need to provide a conductive member for applying a bias potential or a built-in heater of an electric resistance type inside the mounting section 20, and the configuration of the mounting section 20 can be simplified.

[0066] Furthermore, in the above example, the loading section 12 is located vertically below the annular member 31 of the potential application member 30. Therefore, the inner circumferential surface of the sidewall of the chamber 10 (cylindrical section 11) that is vertically above the potential application member 30 can be made cylindrical. This makes it possible to make the flow of gas and plasma in the space vertically above the substrate W more uniform. This in turn makes it possible to make ions and radicals act more uniformly on the top surface of the substrate W. Therefore, the etching apparatus 1 can etch the top surface of the substrate W more uniformly.

[0067] In the above example, the annular member 31 of the potential application member 30 has an annular shape. Specifically, the upper surface of the annular member 31 has a shape that follows the side surface of a truncated cone. This allows the gas flow to be uniform around the substrate W. This allows the etching apparatus 1 to etch the upper surface of the substrate W more uniformly.

[0068] In the above example, the potential application member 30 includes conductive carbon and a silicon carbide film formed on the surface of the conductive carbon. This means that even if plasma containing chlorine ions acts on the potential application member 30, the potential application member 30 is hardly corroded. In other words, the reliability of the potential application member 30 can be improved.

[0069] <Another Example> Fig. 5 is a diagram schematically illustrating another example of the configuration of the etching apparatus 1. In the example of Fig. 5, the lifting drive unit 40 stops the mounting unit 20 at the upper position, and in this state, the potential application member 30 is in contact with the peripheral portion of the upper surface of the substrate W. That is, in a plan view, the inner peripheral edge 31a of the circular member 31 of the potential application member 30 is located inside the peripheral edge of the substrate W. In other words, the inner diameter (diameter) of the circular member 31 is smaller than the diameter of the substrate W. It is preferable that the potential application member 30 be in contact with the peripheral portion of the upper surface of the substrate W where no devices are formed.

[0070] According to this structure, the substrate W is sandwiched between the annular member 31 of the potential application member 30 and the support portion 21. The potential application member 30 presses the peripheral portion of the substrate W toward the support portion 21, so that the lower surface of the substrate W can be brought into closer contact with the upper surface of the support portion 21. This allows the heat of the support portion 21 to be transferred to the substrate W more efficiently. In other words, the heating efficiency for the substrate W can be improved. Furthermore, there is no need to provide a support chuck that contacts and supports the peripheral portion of the substrate W.

[0071] Although the etching apparatus 1 has been described in detail above, the above description is merely an example in all respects, and this disclosure is not limited thereto. Furthermore, the various modifications described above can be combined and applied as long as they are not mutually inconsistent. It is understood that numerous modifications not illustrated can be envisioned without departing from the scope of this disclosure.

[0072] REFERENCE SIGNS LIST 1 Etching device 10 Chamber 11 Cylindrical part 12 Carrying-in part 20 Placement part 21 Support part 30 Potential application member 31 Circular ring member 40 Elevation driving part 50 Plasma generator 81 Light source W Substrate

Claims

1. An etching apparatus comprising: a mounting section on which a portable support section supporting a substrate is placed; a heating section located below the mounting section and including a light source that emits heating light to heat the substrate; a potential application member located above the mounting section and to which a predetermined bias potential is applied; a lifting drive section that raises and lowers the mounting section between an upper position where the potential application member contacts the substrate or the support section and a lower position where the potential application member is separated from the substrate and the support section; and a plasma generator that generates plasma, supplies the plasma to an upper surface of the substrate on the support section placed on the mounting section, and etches the upper surface of the substrate with the plasma.

2. An etching apparatus according to claim 1, wherein the mounting portion is translucent to the light.

3. An etching apparatus according to claim 2, wherein, in the upper position, the potential application member contacts the upper surface of the substrate.

4. An etching apparatus as defined in any one of claims 1 to 3, comprising a chamber, the chamber including: a cylindrical portion for housing the potential application member and the placement portion; and an entrance portion connected to a portion of a side wall of the cylindrical portion below the potential application member, the entrance portion through which the substrate and the support portion pass.

5. An etching apparatus according to any one of claims 1 to 3, wherein the potential application member includes conductive carbon and a silicon carbide film formed on a surface of the conductive carbon.

6. An etching apparatus according to any one of claims 1 to 3, wherein the potential application member includes a ring member having a ring shape in a plan view.

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