Inductively coupled plasma source and substrate processing apparatus
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SCREEN HOLDINGS CO LTD
- Filing Date
- 2025-11-10
- Publication Date
- 2026-07-30
Smart Images
Figure JP2025039341_30072026_PF_FP_ABST
Abstract
Description
Inductive coupling type plasma source and substrate processing apparatus
[0001] The present disclosure relates to an inductive coupling type plasma source and a substrate processing apparatus.
[0002] Conventionally, plasma generation apparatuses for generating inductive coupling plasma have been proposed (for example, Patent Documents 1 and 2). In Patent Document 1, plasma is generated around a planar coil antenna by flowing a high-frequency current through the coil antenna. In Patent Document 2, a plurality of U-shaped inductive coupling antennas are arranged. By flowing a high-frequency current through each inductive coupling antenna, plasma is generated around each inductive coupling antenna.
[0003] Japanese Patent Application Laid-Open No. 2004-31566, Japanese Patent Application Laid-Open No. 2016-160444
[0004] When the plasma source includes a U-shaped inductive coupling antenna, the plasma generated near the U-shaped central portion of the inductive coupling antenna can be used for processing a workpiece (for example, a substrate). The higher the maximum value of the potential at this central portion, the higher the electric field strength around the central portion and the more the ions in the plasma are accelerated. As a result, the damage to the workpiece to be plasma-processed becomes high.
[0005] Therefore, an object of the present disclosure is to provide a technique capable of reducing the potential of the antenna portion.
[0006] The inductive coupling type plasma source includes a conductive antenna portion, a first conductive portion having a rod shape, a first connection portion that is one end of the rod shape and is connected to the antenna portion, and a first power supply portion that is the other end of the rod shape and is connected to a high-frequency power supply portion. A second connection portion connected to the antenna portion, and a second power supply portion to which a ground potential is applied. Together with the first conductive portion and the antenna portion, a U-shaped current path is formed, and a second conductive portion having a cross-sectional area larger than the cross-sectional area of the first conductive portion is provided.
[0007] The substrate processing apparatus comprises a chamber, a substrate placement section provided within the chamber for supporting or holding a substrate, a pressure reduction section for reducing the pressure inside the chamber, a gas supply section for supplying plasma gas into the chamber, and the inductively coupled plasma source provided within the chamber.
[0008] The potential at the first connection point can be reduced.
[0009] Figure 1 is a schematic diagram showing an example of the configuration of a substrate processing apparatus including a plasma source according to an embodiment. Figure 2 is a schematic perspective view showing an example of the configuration of a conductive member. Figure 3 is a schematic cross-sectional view showing a part of the configuration of a conductive member. Figure 4 is a schematic graph showing an example of the potential distribution of a standing wave generated in a conductive member. Figure 5 is a schematic plan view showing another example of the configuration of a conductive member.
[0010] The embodiments will be described in detail below with reference to the drawings. Note that, for the purpose of ease of understanding, the dimensions and number of parts in the drawings are exaggerated or simplified as needed. Also, parts with similar configurations and functions are denoted by the same reference numerals, and redundant explanations will be omitted in the following description.
[0011] Furthermore, in the following explanations, similar components will be denoted by the same symbols, and their names and functions will also be the same. Therefore, detailed explanations of them may be omitted to avoid redundancy.
[0012] Furthermore, even if ordinal numbers such as "first" or "second" are used in the following descriptions, these terms are used for convenience to facilitate understanding of the embodiments and are not limited to the order that may result from these ordinal numbers.
[0013] When expressions indicating relative or absolute positional relationships are used (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.), unless otherwise specified, such expressions shall 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 tolerance or a range in which equivalent functionality is obtained. When expressions indicating equality are used (e.g., "identical," "equal," "homogeneous," etc.), unless otherwise specified, such expressions shall not only strictly represent a state in which there is a quantitatively exact equality but also represent a state in which there is a difference within a tolerance or a range in which equivalent functionality is obtained. When expressions indicating shape are used (e.g., "quadrilateral" or "cylindrical"), unless otherwise specified, such expressions shall not only strictly represent the geometrically exact shape but also represent a shape with features such as concavities or chamfers within a range in which equivalent effects are obtained. When expressions such as "equipped with," "possess," "possess," "include," or "have" a single component are used, such expressions are not exclusive expressions that exclude the existence of other components. When the expression "at least one of A, B, and C" is used, it includes A only, B only, C only, any two of A, B, and C, and all of A, B, and C.
[0014] Figure 1 is a schematic diagram showing an example of the configuration of a substrate processing apparatus 1 including a plasma source 50 according to an embodiment. Note that the plasma source 50 does not necessarily have to be provided in the substrate processing apparatus 1, but can be provided in any apparatus that utilizes plasma. In this embodiment, as an example, the case in which the plasma source 50 is provided in the substrate processing apparatus 1 will be described.
[0015] The substrate processing apparatus 1 is a single-wafer processing apparatus that processes substrates W one at a time. Substrates W include, for example, semiconductor wafers, liquid crystal display substrates, organic electroluminescence (EL) substrates, flat panel display (FPD) substrates, optical display substrates, magnetic disk substrates, optical disk substrates, magneto-optical disk substrates, photomask substrates, and solar cell substrates. Substrates W have a thin, flat shape. In the following, it is assumed that substrate W is a semiconductor wafer. As an example, substrate W is a silicon substrate. Substrate W has, for example, a disc shape. The diameter of substrate W is, for example, about 300 mm, and the thickness of substrate W is, for example, about 0.5 mm or more and about 3 mm or less.
[0016] The substrate processing apparatus 1 includes a chamber 10, a substrate placement section 20, a depressurization section 30, a gas supply section 40, a plasma source 50, and a control section 90.
[0017] Chamber 10 has a box-like shape. The internal space H1 of Chamber 10 corresponds to the processing space for processing the substrate W. Chamber 10 can switch between an loading / unloading state in which the internal space H1 is in communication with the external space, and a sealed state in which the internal space H1 is isolated from the external space. For example, Chamber 10 may be provided with an openable and closable shutter (not shown). When the shutter is opened, Chamber 10 enters the loading / unloading state, and when the shutter is closed, Chamber 10 enters the sealed state. A transport robot (not shown) provided in the external space loads the substrate W into Chamber 10 and unloads the substrate W from Chamber 10 when Chamber 10 is in the loading / unloading state. On the other hand, when Chamber 10 is in the sealed state, plasma processing is performed on the substrate W in the internal space H1 of Chamber 10.
[0018] In the example shown in Figure 1, the chamber 10 is conductive and has a ground potential applied to it. For example, the chamber 10 is made of metal. In the example shown in Figure 1, one end of the wiring 11 is connected to the chamber 10, and the other end of the wiring 11 is grounded.
[0019] The substrate placement section 20 is provided inside the chamber 10. The substrate placement section 20 supports or holds the substrate W in a horizontal position. A horizontal position here means that the thickness direction of the substrate W is aligned with the vertical direction. The substrate placement section 20 may also be a mounting table that supports the substrate W. In the example of Figure 1, the substrate placement section 20 includes a stage 21 and a bias application member 22. The stage 21 has a plate-like shape and is provided with its thickness direction aligned with the vertical direction. The bias application member 22 is provided on the stage 21. The bias application member 22 has, for example, a plate-like shape and is provided with its thickness direction aligned with the vertical direction. The bias application member 22 is conductive. For example, the bias application member 22 is made of metal. In the example of Figure 1, the substrate W is placed on the bias application member 22. The main surface (e.g., the top surface) of the substrate W is exposed inside the chamber 10, and as described later, active species (at least one of ions and radicals) originating from the plasma act on the main surface of the substrate W. This allows plasma treatment to be performed on the substrate W.
[0020] The bias application member 22 has a bias voltage applied by the bias power supply unit 25. The bias power supply unit 25 includes a high-frequency power supply 26 and a matching circuit 27. The high-frequency power supply 26 includes output terminals 26a and 26b, and outputs a high-frequency voltage between output terminals 26a and 26b. Output terminal 26a is connected to the bias application member 22 via the matching circuit 27. The matching circuit 27 is a circuit that matches the power supply impedance and the load impedance. Output terminal 26b is grounded.
[0021] The pressure reduction unit 30 reduces the pressure inside the chamber 10. Specifically, the pressure reduction unit 30 reduces the pressure inside the chamber 10 to a pressure range suitable for processing. For example, the pressure reduction unit 30 may reduce the pressure inside the chamber 10 to 1000 Pa or less, to 100 Pa or less, or to 10 Pa or less. In this way, by reducing the pressure inside the chamber 10 with the pressure reduction unit 30, the chamber 10 becomes a vacuum. The chamber 10 may also be called a vacuum chamber.
[0022] In the example shown in Figure 1, the depressurization unit 30 includes a suction tube 31 and a suction unit 32. The upstream end of the suction tube 31 is connected to the chamber 10. The suction unit 32 is connected to the downstream end of the suction tube 31 and draws gas from the chamber 10 through the suction tube 31. The suction unit 32 includes a pump (e.g., a vacuum pump).
[0023] The gas supply unit 40 supplies plasma gas into the chamber 10. The gas includes, for example, at least one of an inert gas and a reactive gas. The inert gas includes, for example, at least one of nitrogen gas and a noble gas. The noble gas is, for example, argon gas. The reactive gas may be, for example, oxygen gas, or it may be an etching gas for etching the target of etching on the substrate W. The etching gas may be, for example, a fluorine-containing gas containing fluorine. The fluorine-containing gas includes, for example, at least one of hydrogen fluoride gas, carbon fluoride gas, and sulfur fluoride gas.
[0024] The gas supply unit 40 includes a supply pipe 41, a supply valve 42, and a flow control valve 43. The downstream end of the supply pipe 41 is connected to the chamber 10, and the upstream end of the supply pipe 41 is connected to the gas supply source. The gas supply source includes a storage unit (tank) for storing gas. The supply valve 42 is inserted into the supply pipe 41 and switches the supply pipe 41 open and closed. The flow control valve 43 is inserted into the supply pipe 41 and adjusts the flow rate of gas flowing through the supply pipe 41.
[0025] The plasma source 50 is located inside the chamber 10 and generates plasma from the gas inside the chamber 10, causing the plasma-derived active species to act on the main surface of the substrate W. The plasma source 50 is an inductively coupled plasma source.
[0026] As shown in Figure 1, the plasma source 50 includes a conductive member 70. The conductive member 70 is made of a metal such as copper and is electrically conductive. The conductive member 70 functions as an antenna in an inductively coupled plasma source. The conductive member 70 is connected to a high-frequency power supply unit 65. The high-frequency power supply unit 65 supplies a high-frequency current to the conductive member 70. For example, the high-frequency power supply unit 65 supplies a high-frequency current of several tens of MHz (13.56 MHz as a specific example) to the conductive member 70. This creates a high-frequency magnetic field for the plasma around the conductive member 70, and this high-frequency magnetic field causes the gas to become plasma.
[0027] In the example shown in Figure 1, the plasma source 50 is located within the chamber 10, above the substrate placement section 20. The plasma source 50 is positioned perpendicular to the substrate W, which is supported or held by the substrate placement section 20. The gas in the space between the plasma source 50 and the substrate W (hereinafter also referred to as the plasma space) is converted into plasma by the plasma source 50.
[0028] Figure 2 is a schematic perspective view showing an example of the configuration of the conductive member 70. As shown in Figures 1 and 2, the conductive member 70 includes a conductive antenna portion 71, a first conductive portion 72, and a second conductive portion 73.
[0029] In the examples shown in Figures 1 and 2, the conductive member 70 includes a plurality of antenna portions 71. In the examples shown in Figures 1 and 2, each antenna portion 71 has a plate-like shape and is provided with its thickness direction aligned with the vertical direction. The antenna portion 71 may have a circular shape in plan view. Plan view here refers to viewing an object with the line of sight aligned with the vertical direction. As shown in Figure 2, the plurality of antenna portions 71 can be dispersed in a plan view. In the example in Figure 2, six antenna portions 71 are arranged in a ring around one antenna portion 71 in a plane. The number of antenna portions 71 can be changed as appropriate. The arrangement of the antenna portions 71 in a plan view can also be changed as appropriate. For example, the plurality of antenna portions 71 may be arranged in a matrix or staggered pattern in a plan view.
[0030] The first conductive part 72 has a rod-like shape. Hereinafter, one end of the first conductive part 72 in the longitudinal direction will be referred to as the first connection part 72a, and the other end will be referred to as the first power supply part 72b. The first connection part 72a is connected to the antenna part 71, and the first power supply part 72b is connected to the high-frequency power supply part 65. In the examples of Figures 1 and 2, the first conductive part 72 is provided with its longitudinal direction aligned with the vertical direction. In the examples of Figures 1 and 2, the lower end of the first conductive part 72 corresponds to the first connection part 72a, and the upper end of the first conductive part 72 corresponds to the first power supply part 72b. In the example of Figure 2, the first connection part 72a of the first conductive part 72 is connected to the central part of the antenna part 71. In the example of Figure 2, the first conductive part 72 has a cylindrical shape and is provided coaxially with the antenna part 71. That is, the first connection part 72a is connected to the center of the antenna part 71. The diameter of the antenna section 71 is larger than the diameter of the first conductive section 72.
[0031] In the examples shown in Figures 1 and 2, multiple first conductive parts 72 are provided in a one-to-one relationship with multiple antenna parts 71. Therefore, the multiple first conductive parts 72 are distributed in a plan view in the same arrangement as the antenna parts 71.
[0032] The second conductive portion 73 has a second connection portion 73a and a second power supply portion 73b. The second connection portion 73a is connected to the antenna portion 71, and the second power supply portion 73b is grounded. In other words, ground potential is applied to the second power supply portion 73b. The second conductive portion 73, together with the antenna portion 71 and the first conductive portion 72, forms a U-shaped current path, as will be described later (see also Figure 3 below).
[0033] In the example shown in Figure 2, the second conductive portion 73 has a first surface 731, a second surface 732, a side surface 733, and a plurality of holes 734. The first surface 731 corresponds to the second power supply portion 73b. In the examples shown in Figures 1 and 2, the first surface 731 is in contact with the chamber 10, and the ground potential is applied to the first surface 731 through the chamber 10. In the example shown in Figure 1, the first surface 731 (i.e., the second power supply portion 73b) is in contact with the lower surface of the ceiling of the chamber 10. In other words, the first surface 731 corresponds to the upper surface of the second conductive portion 73. The first surface 731 may have a circular shape in plan view. The second surface 732 is the surface of the second conductive portion 73 opposite to the first surface 731. Here, the second surface 732 corresponds to the lower surface of the second conductive portion 73. The second surface 732 may have a circular shape in plan view. The diameter of the second surface 732 may be greater than or equal to the diameter of the substrate W. In other words, the second surface 732 may be wider than the substrate W. The side surface 733 connects the periphery of the first surface 731 and the periphery of the second surface 732.
[0034] Multiple holes 734 are open on the first surface 731 and each extends along the vertical direction. In the example of Figure 2, each hole 734 has a circular shape in plan view. That is, each hole 734 has a cylindrical shape extending along the vertical direction. Each of the multiple holes 734 is provided with an antenna portion 71 and a first conductive portion 72. That is, the multiple holes 734 are provided one-to-one with the multiple antenna portions 71 and one-to-one with the multiple first conductive portions 72.
[0035] In the following, the inner circumferential surface that forms each of the multiple holes 734 in the second conductive portion 73 will simply be referred to as the inner circumferential surface of the second conductive portion 73.
[0036] In the examples shown in Figures 1 and 2, at least a portion of the first conductive portion 72 is located inside the corresponding hole 734. That is, the inner circumferential surface of the second conductive portion 73 has an annular shape that surrounds the first conductive portion 72 at a distance. Specifically, the inner circumferential surface of the second conductive portion 73 has a cylindrical shape with an axis along the longitudinal direction of the first conductive portion 72 as its central axis. The inner circumferential surface of the second conductive portion 73 is coaxial with the second conductive portion 73.
[0037] In the examples shown in Figures 1 and 2, the peripheral edge (second connection portion 73a) of the inner circumferential surface of the second conductive portion 73 on the second surface 732 side is connected to the peripheral portion (side surface) of the antenna portion 71. The antenna portion 71 may also have the hole 734 closed on the second surface 732 side. The main surface (in this case, the bottom surface) of the antenna portion 71 on the second surface 732 side may be flush with the second surface 732 of the second conductive portion 73. The bottom surface of the antenna portion 71 and the second surface 732 of the second conductive portion 73 may be flat surfaces.
[0038] In the examples shown in Figures 1 and 2, the first power supply portion 72b of the first conductive portion 72 is located above the first connection portion 72a, and the second power supply portion 73b of the second conductive portion 73 is located above the second connection portion 73a. In other words, the vertical positional relationship between the first connection portion 72a and the first power supply portion 72b is the same as the vertical positional relationship between the second connection portion 73a and the second power supply portion 73b. To put it another way, the direction in which the first conductive portion 72 extends from the antenna portion 71 is the same as the direction in which the second conductive portion 73 extends from the antenna portion 71.
[0039] In the example shown in Figure 1, a plurality of through holes 12 are formed in the ceiling of the chamber 10. The plurality of through holes 12 penetrate the ceiling of the chamber 10 in a vertical direction. The plurality of through holes 12 are provided one-to-one with a plurality of first conductive parts 72. The first conductive parts 72 penetrate the corresponding through holes 12. Therefore, the first power supply portion 72b of the first conductive part 72 is located in the external space of the chamber 10, and the first connection portion 72a of the first conductive part 72 is located in the internal space H1 of the chamber 10. Since the first power supply portion 72b is provided in the external space of the chamber 10, the high-frequency power supply unit 65 provided in the external space can be electrically connected to the first power supply portion 72b more easily. The through holes 12 may have a circular shape in plan view. The diameter of the through holes 12 may be larger than the diameter of the first conductive part 72. The diameter of the through holes 12 may be smaller than the diameter of the hole 734. This increases the contact area between the ceiling of the chamber 10 and the second conductive part 73 (second power supply part 73b, i.e., the first surface 731), thereby reducing the electrical resistance at the boundary between the chamber 10 and the second conductive part 73.
[0040] In the example shown in Figure 1, the first power supply portion 72b is located above the ceiling of the chamber 10, and the second power supply portion 73b is in contact with the lower surface of the ceiling of the chamber 10, so the first power supply portion 72b is located above the second power supply portion 73b. In other words, in the example shown in Figure 1, the first conductive portion 72 protrudes above the first surface 731 (second power supply portion 73b) of the second conductive portion 73.
[0041] In this embodiment, the cross-sectional area of the second conductive portion 73 is larger than the cross-sectional area of the first conductive portion 72. Here, the cross-sectional area is the area of the cross section perpendicular to the extending direction (i.e., longitudinal direction) of the first conductive portion 72. In the example of Figures 1 and 2, the conductive member 70 includes a plurality of first conductive portions 72. In this case, for example, the cross-sectional area of the second conductive portion 73 is larger than the sum of the cross-sectional areas of the plurality of first conductive portions 72. The cross-sectional area of the second conductive portion 73 may be twice or more the sum of the cross-sectional areas of the plurality of first conductive portions 72, or it may be three times or more.
[0042] In the example shown in Figure 1, the high-frequency power supply unit 65 includes a high-frequency power supply 66 and a matching circuit 67. The high-frequency power supply 66 includes output terminals 66a and 66b, and outputs a high-frequency voltage between output terminals 66a and 66b. Output terminal 66a is connected to each first power supply portion 72b of the first conductive part 72 via the matching circuit 67. The matching circuit 67 is a circuit that matches the power supply impedance with the load impedance. Output terminal 66b is grounded.
[0043] In the example shown in Figure 1, the plasma source 50 also includes a dielectric member 60. The dielectric member 60 may cover at least the portion of the conductive member 70 that avoids the first power supply portion 72b and the second power supply portion 73b. In the example shown in Figure 1, the dielectric member 60 covers at least the entirety of the second surface 732 and the side surface 733. The dielectric member 60 may also be provided inside the hole 734. The dielectric member 60 is formed of an insulating material such as alumina. The dielectric member 60 can protect the conductive member 70 from the plasma in the chamber 10.
[0044] A cooling unit for cooling the plasma source 50 may be provided. The cooling unit may be, for example, a liquid-cooled cooling unit. Specifically, a flow path (not shown) may be formed inside the plasma source 50, and a refrigerant may be flowed through the flow path. Thereby, the temperature rise of the plasma source 50 can be alleviated.
[0045] The control unit 90 controls the substrate processing apparatus 1. Specifically, the control unit 90 controls the decompression unit 30 (for example, the suction unit 32), the gas supply unit 40 (for example, the supply valve 42 and the flow rate adjustment valve 43), the bias power supply unit 25 (for example, the high-frequency power supply 26), and the high-frequency power supply unit 65 (for example, the high-frequency power supply 26). The control unit 90 is, for example, an electronic circuit and may include an arithmetic processing device such as a CPU (Central Processor Unit) and a storage unit. The storage unit may have a non-temporary storage unit (for example, ROM (Read Only Memory) or a hard disk) and a temporary storage unit (for example, RAM (Random Access Memory)). A program that defines the processing executed by the control unit 90 may be stored in the non-temporary storage unit. By the arithmetic processing device executing this program, the control unit 90 can execute the processing defined in the program. Of course, part or all of the processing executed by the control unit 90 may be executed by hardware such as a dedicated logic circuit.
[0046] For example, the control unit 90 controls the decompression unit 30 to reduce the pressure in the chamber 10 to a pressure range suitable for processing while the substrate placement unit 20 supports or holds the substrate W. Further, the control unit 90 controls the gas supply unit 40 to supply gas into the chamber 10. Then, the control unit 90 controls the bias power supply unit 25 and the high-frequency power supply unit 65 to apply a high-frequency voltage to the plasma source 50 while applying a bias voltage to the bias application member 22. Due to the output of the high-frequency voltage of the high-frequency power supply 66, a high-frequency current flows through the conductive member 70.
[0047] FIG. 3 is a cross-sectional view schematically showing a part of the conductive member 70. In FIG. 3, the flow of the high-frequency current is schematically indicated by arrows at both ends. As shown in FIG. 3, the high-frequency current mainly flows along the vertical direction through the first conductive portion 72, mainly flows along the horizontal direction through the antenna portion 71, and mainly flows along the vertical direction through the second conductive portion 73. That is, the high-frequency current flows through the conductive member 70 along a U-shaped current path having the first power supply portion 72b and each second power supply portion 73b at both ends. The high-frequency current flows along the horizontal direction between the first connection portion 72a and the second connection portion 73a (that is, the antenna portion 71) of the current path.
[0048] In the above example, the first connection portion 72a of the first conductive portion 72 is connected to the center of the antenna portion 71 (see FIG. 2), and the second connection portion 73a of the second conductive portion 73 has an annular shape and is connected to the peripheral portion of the antenna portion 71. Therefore, the high-frequency current mainly flows through the antenna portion 71 along the radial direction centered on the first connection portion 72a. That is, the high-frequency current flows radially through the antenna portion 71.
[0049] Due to the high-frequency current flowing through the antenna portion 71, a high-frequency magnetic field is generated in the plasma space between the plasma source 50 and the substrate W. Specifically, a high-frequency magnetic field is generated directly below the antenna portion 7l. As a result, the gas in the plasma space is plasmaized, and the active species derived from the plasma act on the main surface (here, the upper surface) of the substrate W. By this action, for example, the etching target of the substrate W is etched.
[0050] Moreover, in the conductive member 70 according to the present embodiment, the cross-sectional area of the second conductive portion 73 is larger than the cross-sectional area of the first conductive portion 72. Therefore, the electrical resistance of the second conductive portion 73 can be reduced. Therefore, the potential of the second connection portion 73a of the second conductive portion 73 can be made closer to the potential of the second power supply portion 73b (that is, the ground potential). As a result, as will be described in detail below, the potential of the first connection portion 72a of the first conductive portion 72 can be lowered.
[0051] Figure 4 is a schematic graph showing an example of the potential distribution of a standing wave generated in the conductive member 70. In the example in Figure 4, an example of the potential distribution (standing wave) of the conductive member 70 according to this embodiment is schematically shown by a solid line. As shown in Figure 4, the potential of the second connection portion 73a of the conductive member 70 is very close to the ground potential (i.e., 0). This is because the cross-sectional area of the second conductive portion 73 is large and the electrical resistance of the second conductive portion 73 is small, so the potential difference between the second connection portion 73a and the second power supply portion 73b is small. If we consider the potential of the second power supply portion 73b to be the ground potential, then the potential of the second connection portion 73a is close to the ground potential of the second power supply portion 73b. In other words, the second connection portion 73a is located near the node of the standing wave. For simplicity, we will assume here that the potential of the second connection portion 73a is the ground potential.
[0052] For comparison, a hypothetical first comparison structure in which the cross-sectional area of the second conductive part 73 is small will be described. In this first comparison structure, the electrical resistance of the second conductive part 73 is relatively large. As a result, the potential difference between the second connection part 73a and the second power supply part 73b becomes large, and the potential of the second connection part 73a moves away from the ground potential. In other words, the position of the ground potential shifts from the second connection part 73a to the second power supply part 73b side. In Figure 4, an example of the potential distribution (standing wave) over the first comparison structure is schematically shown by a dashed line. As can be seen from Figure 4, the antenna potential Va0 (maximum value) applied to the first connection part 72a in the first comparison structure is higher than the antenna potential Va (maximum value) applied to the first connection part 72a in this embodiment. Conversely, in the plasma source 50 of this embodiment, the antenna potential Va (maximum value) can be reduced.
[0053] As described above, since the cross-sectional area of the second conductive portion 73 in this embodiment is larger than the cross-sectional area of the first conductive portion 72, the antenna potential Va can be reduced. Therefore, the increase in ion velocity in the plasma caused by the antenna potential Va can be mitigated. For example, the electric field strength between the first connection portion 72a (antenna potential Va) and the chamber 10 (ground potential) can be reduced. Therefore, the increase in ion velocity due to the electric field can be mitigated. Consequently, damage to the substrate W by ions can be reduced.
[0054] As described above, when the depressurization unit 30 reduces the pressure inside the chamber 10, the density of gas molecules inside the chamber 10 is low. Therefore, accelerated ions are more likely to collide with the substrate W, and damage to the substrate W is likely to occur. Accordingly, a plasma source 50 that can reduce the antenna potential Va is particularly beneficial for a substrate processing apparatus 1 that processes the substrate W under low pressure conditions inside the chamber 10.
[0055] Furthermore, in the above example, the second conductive portion 73 surrounds the first conductive portion 72 at a distance, the lower end of the first conductive portion 72 (first connection portion 72a) is connected to the center of the antenna portion 71, and the peripheral edge of the hole 734 of the second conductive portion 73 (second connection portion 73a) is connected to the periphery of the antenna portion 71. Therefore, the high-frequency current flows radially through the antenna portion 71 with the first connection portion 72a as the center. In other words, the high-frequency current can flow widely through the antenna portion 71. Consequently, the high-frequency current in the antenna portion 71 can generate a high-frequency magnetic field over a wider area. Thus, the plasma source 50 can generate plasma over a wider area in a plan view.
[0056] Furthermore, in the above example, an antenna portion 71 and a first conductive portion 72 are provided in each of the multiple holes 734 formed in the second conductive portion 73. With this structure, the cross-sectional area of the second conductive portion 73 can be easily increased. Also, with this structure, in a plan view, the conductive member 70 occupies the entire area inside the side surface 733 of the second conductive portion 73. For this reason, the plasma source 50 can generate plasma more uniformly in a plan view compared to a planar coil antenna and a U-shaped inductively coupled antenna.
[0057] Furthermore, this structure allows for easy adjustment of the number of pairs of antenna sections 71 and first conductive sections 72. Figure 5 is a schematic plan view showing another example of the conductive member 70 configuration. In the example of Figure 5, pairs of antenna sections 71 and first conductive sections 72 are arranged in a matrix. By increasing the number of pairs, the total area occupied by the antenna section 71 in a plan view can be increased without increasing the antenna length L of the antenna section 71. The antenna length L here refers to the length of the current path in the portion of the antenna section 71 where the high-frequency current flows horizontally. The antenna length L can also be said to be the distance between the first connection section 72a and the second connection section 73a in a plan view.
[0058] As can be seen from Figure 4, the longer the antenna length L of the antenna section 71, the larger the antenna potential Va (maximum value) of the first connection section 72a becomes. In this embodiment, as described above, by increasing the number of pairs of antenna section 71 and first conductive section 72, the total area occupied by the antenna section 71 in a plan view can be increased without increasing the antenna length L of the antenna section 71. Therefore, while reducing damage to the substrate W, plasma can be generated more uniformly over a wider area. The antenna length L of the antenna section 71 may be one-fifth or less of the wavelength of the potential distribution (standing wave), one-sixth or less, one-seventh or less, one-eighth or less, one-ninth or less, or one-tenth or less. As a specific example, the antenna length L of the antenna section 71 may be set to 30 mm or less, or to 20 mm or less. The antenna length L of the antenna section 71 is set to, for example, about 13 mm.
[0059] For comparison, a U-shaped inductively coupled antenna will also be described. An inductively coupled antenna is made by bending a rod-shaped metal member into a U-shape. Therefore, there are limitations to the curvature of the inductively coupled antenna, making it difficult to reduce the antenna length. In contrast, the structure described above makes it easier to reduce the antenna length.
[0060] Furthermore, in the above example, the antenna portion 71 has a circular shape in plan view. That is, the second connection portion 73a of the second conductive portion 73 has an annular shape. As a result, the high-frequency current flows more isotropically and radially through the antenna portion 71. Therefore, the plasma source 50 can generate a high-frequency magnetic field more isotropically directly below the antenna portion 71, and generate plasma more uniformly.
[0061] Furthermore, in the above example, the first conductive part 72 has a circular shape in plan view. This also causes the high-frequency current to flow more isotropically and radially through the antenna part 71. As a result, the plasma source 50 can generate plasma more uniformly.
[0062] Referring to Figure 5, the minimum distance between the side surface 733 of the second conductive portion 73 and each hole 734 may be, for example, greater than or equal to the diameter of the first conductive portion 72. This allows for an appropriate reduction in the electrical resistance of the outer peripheral portion of the second conductive portion 73.
[0063] As described above, the plasma source 50 and the substrate processing apparatus 1 have been described in detail, but the above description is illustrative in all respects, and this disclosure is not limited thereto. Furthermore, the various modifications described above can be applied in combination as long as they do not contradict each other. And it is understood that a number of modifications not illustrated can be conceivable without falling outside the scope of this disclosure.
[0064] For example, each antenna portion 71 may have a through hole. For example, multiple through holes may be provided at equal intervals in the circumferential direction of the antenna portion 71. In a plan view, each through hole may have a fan shape, and the center of the fan shape may coincide with the center of the antenna portion 71.
[0065] Furthermore, the conductive member 70 may have a U-shaped rod-like form. In this case, the antenna portion 71, the first conductive portion 72, and the second conductive portion 73 all have a rod-like form. The antenna portion 71 corresponds to the central part of the U-shape, the first connection portion 72a of the first conductive portion 72 is connected to one end of the antenna portion 71, and the second connection portion 73a of the second conductive portion 73 is connected to the other end of the antenna portion 71. In other words, the conductive member 70 may be a U-shaped inductively coupled antenna. However, the cross-sectional area of the second conductive portion 73 is larger than the cross-sectional area of the first conductive portion 72. The conductive member 70 differs from conventional inductively coupled antennas in this respect. Even with this conductive member 70, the potential of the first connection portion 72a can be reduced.
[0066] This disclosure includes the following aspects:
[0067] The first embodiment is an inductively coupled plasma source comprising: a conductive antenna portion; a first conductive portion having a rod shape, the first connecting portion which is one end of the rod shape being connected to the antenna portion, and the first power supply portion which is the other end of the rod shape being connected to a high-frequency power supply portion; a second connecting portion which is connected to the antenna portion; and a second power supply portion to which a ground potential is applied, the second conductive portion which together with the first conductive portion and the antenna portion forms a U-shaped current path and has a cross-sectional area larger than the cross-sectional area of the first conductive portion.
[0068] A second embodiment is an inductively coupled plasma source according to the first embodiment, wherein the second conductive portion has an annular inner circumferential surface surrounding the first conductive portion, the first connection portion of the first conductive portion is connected to the central portion of the antenna portion, and the second connection portion, which is the peripheral edge of the inner circumferential surface of the second conductive portion, is connected to the peripheral portion of the antenna portion.
[0069] A third embodiment is an inductively coupled plasma source according to the second embodiment, wherein the second conductive portion has a first surface which is the second power supply portion, a second surface on the opposite side of the first surface, a side surface connecting the periphery of the first surface and the periphery of the second surface, and a plurality of holes opening in the first surface, the plurality of first conductive portions are each provided in the plurality of holes and surrounded by the second conductive portion, and the plurality of antenna portions are each connected to a first connection portion which is the end of the plurality of first conductive portions on the second surface side and to a second connection portion which is the peripheral edge end on the second surface side of the inner circumferential surface of the plurality of holes.
[0070] A fourth embodiment is an inductively coupled plasma source according to the third embodiment, wherein each of the plurality of holes has a circular shape in plan view.
[0071] A fifth embodiment is an inductively coupled plasma source according to the third or fourth embodiment, wherein each of the plurality of first conductive parts has a cylindrical shape.
[0072] The sixth embodiment is a substrate processing apparatus comprising a chamber, a substrate placement section provided within the chamber for supporting or holding a substrate, a pressure reduction section for reducing the pressure inside the chamber, a gas supply section for supplying plasma gas into the chamber, and an inductively coupled plasma source according to any one of the first to fifth embodiments provided within the chamber.
[0073] According to the first embodiment, the electrical resistance of the second conductive part can be reduced, thereby reducing the potential difference between the second connection part and the second power supply part. In other words, the potential of the second connection part can be brought closer to the ground potential. Therefore, in the potential distribution (standing wave) of the conductive member including the antenna part, the first conductive part, and the second conductive part, the second connection part is located near the node. Consequently, the potential (maximum value) of the first connection part can be reduced.
[0074] According to the second embodiment, since the second conductive part surrounds the first conductive part, the high-frequency current flows radially through the antenna part with the first connection part as the center. As a result, the high-frequency current in the antenna part can generate a high-frequency magnetic field over a wide area, and the plasma source can generate plasma over an even wider area.
[0075] According to the third embodiment, a pair of first conductive part and antenna part is provided in each of the multiple holes. Therefore, the plasma source can generate plasma over a wider area without increasing the length of the antenna part.
[0076] According to the fourth embodiment, the high-frequency current flows more isotropically and radially through the antenna. As a result, the plasma source can generate plasma more uniformly.
[0077] According to the fifth embodiment, the high-frequency current flows more isotropically and radially through the antenna. As a result, the plasma source can generate plasma more uniformly.
[0078] According to the sixth aspect, damage to the substrate caused by ions in the plasma can be reduced.
[0079] 1 Substrate processing apparatus 10 Chamber 20 Substrate placement section 30 Reduced pressure section 40 Gas supply section 50 Plasma source 71 Antenna section 72 First conductive section 72a First connection section 72b First power supply section 73 Second conductive section 731 First surface 732 Second surface 733 Side surface 734 Hole 73a Second connection section 73b Second power supply section W Substrate
Claims
1. An inductively coupled plasma source comprising: a conductive antenna section; a first conductive section having a rod shape, with one end of the rod shape being a first connecting section connected to the antenna section and the other end of the rod shape being a first power supply section connected to a high-frequency power supply section; a second connecting section connected to the antenna section; and a second power supply section to which ground potential is applied, the second conductive section together with the first conductive section and the antenna section forming a U-shaped current path and having a cross-sectional area larger than that of the first conductive section.
2. An inductively coupled plasma source according to claim 1, wherein the second conductive portion has an annular inner surface surrounding the first conductive portion, the first connection portion of the first conductive portion is connected to the central portion of the antenna portion, and the second connection portion, which is the peripheral edge of the inner surface of the second conductive portion, is connected to the peripheral portion of the antenna portion.
3. An inductively coupled plasma source according to claim 2, wherein the second conductive portion has a first surface which is the second power supply portion, a second surface on the opposite side of the first surface, a side surface connecting the periphery of the first surface and the periphery of the second surface, and a plurality of holes opening in the first surface, the plurality of first conductive portions are each provided in the plurality of holes and surrounded by the second conductive portion, and the plurality of antenna portions are each connected to a first connecting portion which is the end of the plurality of first conductive portions on the second surface side and to a second connecting portion which is the peripheral edge end on the second surface side of the inner circumferential surface of the plurality of holes.
4. An inductively coupled plasma source according to claim 3, wherein each of the plurality of holes has a circular shape in plan view.
5. An inductively coupled plasma source according to claim 3 or claim 4, wherein each of the plurality of first conductive parts has a cylindrical shape.
6. A substrate processing apparatus comprising: a chamber; a substrate placement section provided within the chamber for supporting or holding a substrate; a pressure reduction section for reducing the pressure inside the chamber; a gas supply section for supplying plasma gas into the chamber; and an inductively coupled plasma source according to any one of claims 1 to 4 provided within the chamber.