Plasma processing device and plasma processing method

Abstract

This plasma processing device comprises: a processing container; a first stage and a second stage that are arranged in an internal space of the processing container and on which substrates are placed individually; an antenna arranged outside the internal space and above the first stage and the second stage; and a high-frequency power supply for supplying high-frequency power to the antenna. A ceiling section of the processing container is composed of a dielectric member. The internal space comprises a plasma generation space in which plasma is generated by induced electromotive force from the antenna, and a substrate processing space in which the first stage and the second stage are arranged. The plasma generation space communicates with an area between the area above the first stage and the area above the second stage, and the substrate processing space communicates with the area between the area above first stage and the area above the second stage.

Description

Plasma processing apparatus and plasma processing method

[0001] The present disclosure relates to a plasma processing apparatus and a plasma processing method.

[0002] Patent Document 1 discloses a substrate processing apparatus capable of appropriately removing reaction products generated when etching a film to be etched. The apparatus disclosed in Patent Document 1 includes a configuration equipped with a high-frequency antenna, and the high-frequency antenna includes an inner antenna element and an outer antenna element each having a spiral coil shape.

[0003] Japan Patent Publication No. 2017-85161

[0004] The techniques disclosed herein appropriately generate plasma.

[0005] One aspect of the present disclosure is a plasma processing apparatus comprising: a processing vessel; first and second stages disposed within the internal space of the processing vessel and each stage supporting a substrate; an antenna disposed outside the internal space above the first and second stages; and a high-frequency power supply that supplies high-frequency power to the antenna; wherein the ceiling of the processing vessel is constructed from a dielectric material; the internal space comprises a plasma generation space in which plasma is generated by induced electromotive force from the antenna; and a substrate processing space in which the first and second stages are disposed; the plasma generation space is connected between the upper portion of the first stage and the upper portion of the second stage; and the substrate processing space is connected between the upper portion of the first stage and the upper portion of the second stage.

[0006] According to the present disclosure, plasma can be generated appropriately.

[0007] Fig. 1 is a plan view showing an example of the configuration of a vacuum processing system according to an embodiment; Fig. 2 is a longitudinal sectional view showing an outline of the configuration of a plasma processing apparatus according to an embodiment; Fig. 3 is a plan view showing an outline of the configuration of a processing vessel and an antenna according to an embodiment; Fig. 4 is an explanatory view showing an outline of a high-frequency circuit according to an embodiment; Fig. 5 is a plan view showing an outline of the configuration of an antenna according to a modified example; Fig. 6 is a plan view showing an outline of the configuration of an antenna according to another modified example.

[0008] In a manufacturing process for semiconductor devices and the like, a plasma process such as etching is performed on a semiconductor substrate (hereinafter simply referred to as a "substrate") using plasma. As an example, in this plasma process, an RF (Radio Frequency) signal is supplied to an RF antenna element (hereinafter simply referred to as an "antenna") including a coil disposed above a processing chamber that contains the substrate to be processed, thereby generating inductively coupled plasma (ICP) in the processing chamber.

[0009] The antenna constituting the RF circuit is disposed above a stage on which a substrate is placed. For example, Patent Document 1 discloses an antenna disposed above the upper wall of a processing vessel. In Patent Document 1, the upper wall of the processing vessel is made of a conductive material such as aluminum, and a cylindrical hole is formed in a portion of the upper wall facing the antenna, and a dielectric window is fitted into the hole. The induced electromotive force generated by the antenna passes through the dielectric window directly below and is transmitted to a plasma generation space inside the processing vessel, generating plasma.

[0010] However, in a conductive member such as aluminum outside the dielectric window on the top wall of the processing vessel, a current flows in a direction that cancels out the induced electromotive force generated by the antenna, weakening the induced electromotive force transmitted to the plasma generation space. Furthermore, the diameter and thickness of the dielectric window limit the outer diameter of the antenna, the distance between the outer periphery of the inner antenna and the inner periphery of the outer antenna, and the distance from the antenna to the plasma generation space. If the configuration and arrangement of the outer periphery of the inner coil and the outer coil included in the antenna are limited, for example, the generated plasma may have a ring shape, and the adjustment range of the plasma density distribution is also limited.

[0011] An apparatus for performing plasma processing, in which a processing chamber is provided with multiple stages and a substrate is placed on each stage, is known. In this apparatus, an antenna is provided above each stage, and the plasma generation space and the substrate processing space corresponding to each stage are separated by a partition wall. When the antenna disclosed in Patent Document 1 is used in this apparatus, the antenna configuration and placement are more limited to avoid interference between adjacent antennas. Therefore, there is room for improvement in terms of appropriate plasma generation, such as increasing the degree of freedom in the antenna configuration and placement, and increasing the size and adjustable range of the plasma diameter.

[0012] The technology disclosed herein has been made in consideration of the above circumstances, and appropriately generates plasma. Hereinafter, a plasma processing apparatus and a plasma processing method using the plasma processing apparatus according to this embodiment will be described with reference to the drawings. Note that in this specification and the drawings, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0013] 1, the vacuum processing system 1 includes an atmospheric section 10 and a decompression section 30, which are integrally connected via a load lock module 20.

[0014] The atmospheric section 10 has a load port 11 on which a FOUP F capable of storing multiple substrates W is placed, a cooling storage 12 for cooling the substrates W after processing in the reduced pressure section 30, an aligner module 13 for adjusting the horizontal orientation of the substrates W, and a loader module 14 for transporting the substrates W within the atmospheric section 10.

[0015] The loader module 14 comprises a rectangular housing, and the interior of the housing is maintained at atmospheric pressure. A plurality of, for example, three load ports 11 are arranged side by side on one side that constitutes the long side of the housing of the loader module 14. A plurality of, for example, two load lock modules 20 are arranged side by side on the other side that constitutes the long side of the housing of the loader module 14. A cooling storage 12 is provided on one side that constitutes the short side of the housing of the loader module 14. An aligner module 13 is provided on the other side that constitutes the short side of the housing of the loader module 14.

[0016] A wafer transport mechanism (not shown) for transporting the substrate W is provided inside the loader module 14. The wafer transport mechanism has a transport arm (not shown) that holds and moves the substrate W, and is configured to be able to transport the substrate W to each of the FOUP F placed on the load port 11, the cooling storage 12, the aligner module 13, and the load lock module 20.

[0017] Each load lock module 20 temporarily holds a substrate W transferred from a loader module 14 (described later) in the atmospheric section 10, in order to transfer the substrate W to a transfer module 31 (described later) in the decompression section 30. The load lock module 20 has multiple stockers (not shown) therein, for example, two stockers, which allow two substrates W to be held simultaneously. Each load lock module 20 also has a gate valve (not shown) for ensuring airtightness with respect to the loader module 14 and the transfer module 31 (described later). These gate valves ensure airtightness and mutual communication between the loader module 14 and the transfer module 31 and the loader module 14. Furthermore, each load lock module 20 is connected to a gas inlet (not shown) and a gas outlet (not shown), allowing the interior to be switched between atmospheric pressure and reduced pressure. That is, the load lock module 20 is configured to appropriately transfer a substrate W between the atmospheric section 10, which has an atmospheric pressure atmosphere, and the reduced pressure section 30, which has a reduced pressure atmosphere.

[0018] The decompression section 30 has a transfer module 31 that simultaneously transports two substrates W, and a plasma processing device 32 that performs desired plasma processing on the substrates W carried in from the transfer module 31. The interiors of the transfer module 31 and the plasma processing device 32 are each maintained in a decompressed atmosphere. A plurality of, for example, six plasma processing devices 32 are provided for each transfer module 31.

[0019] The transfer module 31 has an internal rectangular housing, and as described above, is connected to each of the load lock modules 20 via gate valves. The transfer module 31 transports the substrate W loaded into the load lock module 20 to one of the plasma processing devices 32, where it is subjected to plasma processing, and then transports the substrate W via the load lock module 20 to the atmospheric section 10.

[0020] A wafer transfer mechanism 40 for transferring substrates W is provided inside the transfer module 31. The wafer transfer mechanism 40 has transfer arms 41, 41 that hold and move two substrates W aligned vertically, a rotary table 42 that rotatably supports the transfer arms 41, 41, and a rotary table 43 on which the rotary table 42 is mounted. Also, a guide rail 44 extending in the longitudinal direction of the transfer module 31 is provided inside the transfer module 31. The rotary table 43 is mounted on the guide rail 44, and the wafer transfer mechanism 40 is configured to be movable along the guide rail 44.

[0021] The plasma processing apparatus 32 has a gate valve 32a (see FIG. 2) for ensuring airtightness relative to the transfer module 31. This gate valve 32a ensures airtightness between the transfer module 31 and the plasma processing apparatus 32 while also allowing communication between them. The plasma processing apparatus 32 also has two stages, a first stage 51 and a second stage 52, on which two substrates W are placed side by side in the horizontal direction. Hereinafter, the first stage 51 and the second stage 52 may be collectively referred to simply as "stages 51, 52." The plasma processing apparatus 32 performs any desired plasma processing on two substrates W simultaneously by placing the substrates W side by side on the stages 51, 52. The detailed configuration of the plasma processing apparatus 32 will be described later.

[0022] The vacuum processing system 1 described above is provided with at least one controller 50, as shown in FIG. 1 . The controller 50 processes computer-executable instructions that cause the vacuum processing system 1 to perform the various processes described herein. The controller 50 may be configured to control each element of the vacuum processing system 1 to perform the various processes described herein. In one embodiment, part or all of the controller 50 may be included in the vacuum processing system 1. The controller 50 may include a processing unit, a memory unit, and a communication interface. The controller 50 may be implemented, for example, by a computer. The processing unit may be configured to read from the memory unit a program that provides logic or routines that enable various control operations and execute the read program to perform the various control operations. This program may be stored in the memory unit in advance or may be acquired via a medium when needed. The acquired program is stored in the memory unit and read from the memory unit by the processing unit for execution. The medium may be various computer-readable storage media or a communication line connected to the communication interface. The storage medium may be temporary or non-temporary. The processing unit may be a CPU (Central Processing Unit) or one or more circuits. The storage unit may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface may communicate with the vacuum processing system 1 via a communication line such as a LAN (Local Area Network).

[0023] <Plasma Processing Apparatus> Next, the configuration of the above-mentioned plasma processing apparatus 32 will be described in detail. Fig. 2 is a longitudinal cross-sectional view taken along the line A-A in Fig. 3, showing an outline of the configuration of the plasma processing apparatus 32. Fig. 3 is a plan view showing an outline of the configuration of the processing vessel 60 and the antenna 91. For ease of explanation, the housing, matching box, and power splitter are omitted from Fig. 3.

[0024] 2 and 3 , the plasma processing apparatus 32 includes a sealed processing vessel 60 that accommodates a substrate W. The processing vessel 60 includes a wall 61 that serves as a sidewall and a bottom wall and is made of, for example, aluminum or an aluminum alloy. The upper end of the processing vessel 60 is open, and the upper end of the processing vessel 60 is airtightly closed by a lid 62 that serves as a ceiling. The lid 62 of the processing vessel 60 is made of a dielectric material such as alumina and serves as a dielectric window. In other words, the entire ceiling of the processing vessel 60 according to this embodiment is made of a dielectric material.

[0025] A loading / unloading port (not shown) for the substrate W is provided on the side of the processing vessel 60, and the loading / unloading port can be opened and closed by the gate valve 32a described above.

[0026] The internal space of the processing vessel 60 is divided into an upper plasma generation space S1 and a lower substrate processing space S2 by a partition plate 70. The plasma generation space S1 is a space where plasma is generated, and the substrate processing space S2 is a space where plasma processing is performed on the substrate W.

[0027] The partition plate 70 includes at least two (three in this embodiment) plate-like members 71-73, arranged to overlap with a gap from the plasma generation space S1 toward the substrate processing space S2. Each of the plate-like members 71-73 has a slit 71a-73a formed through it in the overlapping direction. In this embodiment, the slits 71a-73a are arranged so that they do not overlap with adjacent plate-like members in a planar view. This allows the partition plate 70 to function as a so-called ion trap, preventing ions in the plasma from passing into the substrate processing space S2 when plasma is generated in the plasma generation space S1. More specifically, the labyrinth structure in which the slits 71a-73a are arranged so as not to overlap prevents anisotropically moving ions from passing through while allowing isotropically moving radicals to pass through. In one embodiment, at least some of the slits are arranged so that they overlap in a planar view. This reduces radical deactivation. In another embodiment, a voltage is applied to the plate-like members 71-73 of the partition plate 70. In this case, the amount of ions and radicals transmitted can be adjusted by adjusting the applied voltage.

[0028] The plasma generation space S1 communicates with the space above the first stage 51 and the space above the second stage 52. The substrate processing space S2 communicates with the space above the first stage 51 and the space above the second stage 52. In other words, the plasma generation space S1 does not have a partition wall that separates the space above the first stage 51 from the space above the second stage 52. The substrate processing space S2 does not have a partition wall that separates the space above the first stage 51 from the space above the second stage 52.

[0029] The plasma generating space S1 is provided with a gas supply unit 80 that supplies a processing gas into the processing vessel 60, and a plasma generating unit 90 that converts the processing gas supplied into the processing vessel 60 into plasma.

[0030] A plurality of gas supply sources (not shown) are connected to the gas supply unit 80, and a desired processing gas is supplied into the processing vessel 60 according to the purpose of the plasma processing of the substrate W. The processing gas supplied to the processing vessel 60 is, for example, O２ The processing gas may be an oxygen-containing gas such as nitrogen or a mixed gas containing a dilution gas such as Ar gas. The gas supply unit 80 is also provided with a flow rate regulator (not shown) for regulating the amount of processing gas supplied to the plasma generation space S1. The flow rate regulator includes, for example, an on-off valve and a mass flow controller. The gas supply unit 80 may also be configured to supply gas to the substrate processing space S2.

[0031] The plasma generating unit 90 is configured as an inductively coupled device that uses an RF antenna (hereinafter referred to as "antenna 91").

[0032] The antenna 91 according to this embodiment is embedded inside the lid 62 in the thickness direction. The antenna 91 is connected to a high-frequency power supply 93 that outputs high-frequency power at a constant frequency (usually 13.56 MHz or higher) suitable for generating plasma at an arbitrary output value via a matching device 92 having a matching circuit for matching the impedances on the power supply side and the load side.

[0033] As shown in FIG. 3 , the antenna 91 is an antenna assembly including multiple coils. Specifically, the antenna 91 includes a first main coil 101 and a first sub-coil 102 provided above the first stage 51, and a second main coil 103 and a second sub-coil 104 provided above the second stage 52. The first main coil 101 is provided radially outward of the first sub-coil 102 so as to surround the first sub-coil 102 in a planar view. The second main coil 103 is provided radially outward of the second sub-coil 104 so as to surround the second sub-coil 104 in a planar view. Hereinafter, the first main coil 101, the first sub-coil 102, the second main coil 103, and the second sub-coil 104 may be collectively referred to simply as "coils 101 to 104." Each of the coils 101 to 104 is made of a conductor such as copper, aluminum, or stainless steel.

[0034] 3, in a plan view seen from above, the first main coil 101 and the first sub coil 102 are configured in a right-handed spiral shape, and the second main coil 103 and the second sub coil 104 are configured in a left-handed spiral shape. In this specification, "right-handed" refers to the direction from the inner peripheral end to the outer peripheral end of the coil being clockwise, and "left-handed" refers to the direction from the inner peripheral end to the outer peripheral end of the coil being counterclockwise.

[0035] The first main coil 101 and the second main coil 103 are connected at an outer circumferential end 101 a of the first main coil 101 and an outer circumferential end 103 a of the second main coil 103 .

[0036] Each of the coils 101 to 104 is connected to a high-frequency power supply 93 and a power splitter 110 (described later). In this embodiment, an outer peripheral end 101a of the first main coil 101, an outer peripheral end 102a of the first sub-coil 102, an outer peripheral end 103a of the second main coil 103, and an outer peripheral end 104a of the second sub-coil 104 are connected to the high-frequency power supply 93 via conductors 111. An inner peripheral end 101b of the first main coil 101, an inner peripheral end 102b of the first sub-coil 102, an inner peripheral end 103b of the second main coil 103, and an inner peripheral end 104b of the second sub-coil 104 are connected to the power splitter 110 (described later) via conductors 112, 113, 114, and 115, respectively.

[0037] A first stage 51 and a second stage 52 are disposed within the substrate processing space S2, each of which horizontally supports a single substrate W. Each stage 51, 52 has a generally cylindrical shape and includes an upper stage 51 a, 52 a on which the substrate W is supported, and a lower stage 51 b, 52 b that supports the upper stage 51 a, 52 a. Temperature control mechanisms 121, 122 for adjusting the temperature of the substrate W are provided within the upper stage 51 a, 52 a. The lower stage 51 b, 52 b is provided with rotation mechanisms 123, 124 for rotating at least the support surfaces 51 c, 52 c of the upper stage 51 a, 52 a, on which the substrate is supported, in a horizontal direction in situ. Drive devices 125, 126 for driving the rotation of the rotation mechanisms 123, 124 are connected to the rotation mechanisms 123, 124. By rotating the mounting surfaces 51c and 52c, the substrates W mounted on the stages 51 and 52 can be rotated in place in the horizontal direction.

[0038] An exhaust unit 130 is provided at the bottom of the processing vessel 60. The exhaust unit 130 is connected to an exhaust mechanism (not shown), such as a vacuum pump, via an exhaust pipe connected to the substrate processing space S2. An automatic pressure control valve (APC) is also provided in the exhaust pipe. The pressure inside the processing vessel 60 is controlled by the exhaust mechanism and the automatic pressure control valve.

[0039] The operation of the plasma processing apparatus 32 can be controlled by the above-described control device 50. In other words, the above-described control device 50 may store a program for controlling the processing of the substrate W in the plasma processing apparatus 32. However, the control device that controls the operation of the plasma processing apparatus 32 does not necessarily have to be the above-described control device 50 provided outside the plasma processing apparatus 32. For example, the operation of the plasma processing apparatus 32 or each of its components may be controlled by using a control unit (not shown) that is provided independently in the plasma processing apparatus 32 or each of its components.

[0040] 4 is an explanatory diagram showing an outline of a high-frequency circuit 200 including an antenna 91, a high-frequency power supply 93, and a power splitter 110 according to this embodiment. In FIG. 4, variable capacitors 201 to 204 included in the power splitter 110 are connected to the first main coil 101, the first sub-coil 102, the second main coil 103, and the second sub-coil 104, respectively. In one embodiment, the variable capacitors 201 to 204 are variable capacitors. The end of the power splitter 110 opposite to the end connected to the antenna 91 is connected to ground potential.

[0041] In the following description, in the parallel portion of the high-frequency circuit 200, the branch path including the first main coil 101 and the variable capacitor 201 will be referred to as the first system, the branch path including the first sub-coil 102 and the variable capacitor 202 will be referred to as the second system, the branch path including the second main coil 103 and the variable capacitor 203 will be referred to as the third system, and the branch path including the second sub-coil 104 and the variable capacitor 204 will be referred to as the fourth system.

[0042] The power splitter 110 includes a desired measuring unit (not shown) that measures or calculates the current or power and impedance of the first to fourth systems. The power splitter 110 is controlled to change the capacitive reactance by changing the positions of the variable capacitors 201 to 204 based on the current or power and impedance measured or calculated by the measuring unit, thereby changing the impedance of the first to fourth systems. By adjusting the first to fourth systems to the desired impedance ratio, the current ratio or power ratio of each of the coils 101 to 104 is adjusted.

[0043] Furthermore, by changing the capacitive reactance of the variable capacitors 201 to 204, the direction (current phase) of the AC current flowing through each of the coils 101 to 104 can be reversed.

[0044] Furthermore, when generating plasma, the impedance of the high frequency circuit 200 is matched to the impedance of the plasma as a load by the matching box 92 while the power splitter 110 maintains the coils 101 to 104 at a desired current ratio or power ratio.

[0045] According to the lid body 62 of this embodiment, the entire body is configured as a dielectric window, so that a conductive member is not adjacent to the induced electromotive force generated in the antenna 91. Therefore, no current flows in a direction that cancels out the induced electromotive force, and the induced electromotive force can be efficiently transmitted to the plasma generation space S1.

[0046] From another perspective, in the past, when the antenna 91 was adjacent to a conductive member, it was necessary to design the antenna 91 so as to be spaced apart from the conductive member, which forced the outer diameter of the outer coil corresponding to the first main coil 101 or the second main coil 103 according to this embodiment to be small. In such a conventional case, the generated plasma had a small diameter, which posed a problem in terms of improving the plasma density near the edge of the substrate W. In contrast, with the lid 62 and antenna 91 according to this embodiment, the antenna 91 is not adjacent to a conductive member, so the outer diameters of the first main coil 101 and the second main coil 103 can be made large. Specifically, as an example, the outer diameters of the first main coil 101 and the second main coil 103 can be made larger than the outer diameter of the substrate W. This makes it possible to generate plasma with a large diameter relative to the diameter of the substrate W, thereby increasing the plasma density, particularly near the edge of the substrate W.

[0047] Furthermore, in the processing vessel 60 according to this embodiment, the plasma generation space S1 and the substrate processing space S2 are not provided with a partition wall that separates the space above the first stage 51 from the space above the second stage 52. By adopting a configuration without a partition wall, a conductive member is not adjacent to the induced electromotive force generated in the antenna 91, and the outer diameters of the first main coil 101 and the second main coil 103 can be made larger.

[0048] Furthermore, since the antenna 91 according to this embodiment is embedded in the lid 62, the distance between the antenna 91 and the plasma generation space S1 can be made shorter than when the antenna 91 is provided above the lid 62. This makes it possible to improve the plasma generation efficiency or reduce the RF power required for plasma generation.

[0049] In one embodiment, the antenna 91 is provided above, not inside, the lid body 62. Even in this case, the distance between the antenna 91 and the plasma generation space S1 is greater than when the antenna 91 is provided inside, but the effect of being able to increase the outer diameters of the first main coil 101 and the second main coil 103 can be sufficiently obtained.

[0050] Furthermore, by increasing the outer diameters of the first main coil 101 and the second main coil 103, it is possible to increase the distance between the first main coil 101 and the first sub-coil 102 and the distance between the second main coil 103 and the second sub-coil 104. This reduces the influence of the coil currents between the first main coil 101 and the first sub-coil 102 and between the second main coil 103 and the second sub-coil 104. This makes it possible to position the peak of the combined induced electromotive force generated in the plasma generation space S1 by the coil currents of both coils near directly below each coil. As a result, plasma can be generated independently in each coil 101 to 104, improving the controllability of the plasma density distribution.

[0051] It is also possible to increase the number of turns of each coil by increasing the outer diameter of the first main coil 101 and the second main coil 103. Note that the number of turns of each coil is not limited to the examples shown in Figures 2 and 3, and can be set to a desired number of turns in consideration of the desired plasma density, power consumption, and the like.

[0052] Furthermore, the power splitter 110 according to this embodiment can control the current ratio or power ratio in the coils 101 to 104 and the current phase in each of the coils 101 to 104. The induced electromotive forces generated by the currents in the coils 101 to 104 influence each other, and strengthen or weaken each other depending on the current phase (in-phase or opposite phase) in each of the coils. By combining the current phases in the coils 101 to 104 (2 x 2 x 2 = 8 combinations), the distribution characteristics of the composite induced electromotive force, and therefore the plasma density distribution characteristics, can be changed.

[0053] Furthermore, the first stage 51 and the second stage 52 according to this embodiment can rotate the mounting surfaces 51 c and 52 c using the rotation mechanisms 123 and 124, thereby rotating the substrate W mounted on each stage 51, 52 in the horizontal direction on the spot. In this regard, in the antenna 91 according to this embodiment, the first main coil 101 and the second main coil 103 are in contact with each other at their outer peripheral ends 101 a and 103 a. Therefore, in the vicinity of the outer peripheral ends 101 a and 103 a where the first main coil 101 and the second main coil 103 are in contact (hereinafter referred to as the "antenna central portion"), when the current phases in the first main coil 101 and the second main coil 103 are in phase, the induced electromotive forces reinforce each other, thereby increasing the plasma density. On the other hand, when the current phases are opposite, the induced electromotive forces weaken each other, thereby decreasing the plasma density. Therefore, a higher or lower density plasma can be generated in this antenna central portion compared to other regions. Even in this case, by rotating the substrate W placed on each stage 51, 52 horizontally on the spot, it is possible to average out the plasma density imbalance between the center of the antenna and other areas within the surface of the substrate W.

[0054] Furthermore, the high-frequency power supply 93 according to this embodiment is provided as a single power supply commonly used for the first main coil 101, the first sub-coil 102, the second main coil 103, and the second sub-coil 104 of the antenna 91. Therefore, the high-frequency power oscillated by the high-frequency power supply 93 is single-phase. As a result, when two or more high-frequency power supplies are connected to each of the coils 101 to 104 as in the conventional case, frequency interference that may occur in each of the coils 101 to 104 due to a phase shift in the high-frequency power oscillated from each high-frequency power supply can be suppressed.

[0055] Furthermore, since a single high-frequency power supply 93 is provided in this embodiment, and a single matching device 92 is also provided, costs can be reduced and space can be saved compared to the conventional case in which two or more high-frequency power supplies and matching devices are used for each of the coils 101 to 104.

[0056] <Plasma Processing Method> Next, a plasma processing method for a substrate W performed using the plasma processing apparatus 32 will be described.

[0057] When plasma processing a substrate W, first, the substrate W to be processed is placed on each of the stages 51, 52 in the substrate processing space S2. The substrate W to be processed is removed from the FOUP F placed on the load port 11 by a wafer transfer mechanism (not shown), and after its horizontal orientation is adjusted in the aligner module 13, it is carried into the plasma processing apparatus 32 via the load lock module 20 and the wafer transfer mechanism 40, and then placed on each of the stages 51, 52.

[0058] During plasma processing, plasma generated in the plasma generation space S1 is supplied to the substrate processing space S2 via the partition plate 70. Here, because the partition plate 70 has a labyrinth structure as described above, only radicals generated in the plasma generation space S1 penetrate into the substrate processing space S2. The radicals supplied to the substrate processing space S2 are then made to act on the substrate W on each stage 51, 52, thereby performing plasma processing on the substrate W.

[0059] A high-frequency circuit 200 is used to generate plasma in the plasma generation space S1. Specifically, high-frequency power is supplied from a high-frequency power supply 93 to each of the coils 101 to 104 constituting the antenna 91. At this time, the positions of the variable capacitors 201 to 204 included in the power splitter 110 are controlled to adjust the impedance ratio of the first to fourth systems, thereby adjusting the current ratio or power ratio. The current phase of each of the coils 101 to 104 is also adjusted. In one embodiment, the positions of the variable capacitors 201 to 204 are controlled so that the current phases of the coils 101 to 104 are in phase. In another embodiment, the positions of the variable capacitors 201 to 204 are controlled so that the impedances of the first to fourth systems are inductive. In this case, the induced electromotive forces generated by the currents in the coils 101 to 104 reinforce each other, increasing the plasma density at the center of the antenna.

[0060] When plasma is generated, the matching device 92 is controlled so that the impedance of the high-frequency circuit 200 matches the impedance of the plasma. In one embodiment, impedance matching is performed in the matching device 92 while the current ratio or power ratio of each of the coils 101 to 104 is kept constant.

[0061] In one embodiment, a correlation between the current ratio or power ratio of each of the coils 101-104 and the position of each of the variable capacitors 201-204 is obtained in advance. Specifically, for example, while high-frequency power is supplied to the high-frequency circuit 200, the positions of the variable capacitors 201-204 are changed while the current ratio or power ratio of the coils 101-104 is monitored by a measurement unit (not shown) in the power splitter 110. At this time, the current ratio or power ratio of the coils 101-104 for each position of the variable capacitors 201-204 is stored and determined as the correlation. In one embodiment, when plasma is generated, the positions of the variable capacitors 201-204 corresponding to the desired current ratio or power ratio of the coils 101-104 are read out, and control is performed to move the variable capacitors to those positions.

[0062] In one embodiment, during plasma generation, the positions of the variable capacitors 201 to 204 are feedback-controlled while the current ratio or power ratio of the coils 101 to 104 is monitored by a measuring unit (not shown) in the power splitter 110. This allows the current ratio or power ratio of the coils 101 to 104 to be controlled in real time during plasma generation, improving the degree of freedom in adjusting the plasma density distribution.

[0063] During the plasma processing, the stages 51 and 52 rotate the mounting surfaces 51c and 52c by the rotation mechanisms 123 and 124, thereby rotating the substrate W mounted on each stage 51 and 52 in place in the horizontal direction.

[0064] Thereafter, when the desired processing result is obtained for the substrate W, the plasma processing is terminated in the plasma processing apparatus 32. When the plasma processing is terminated, the supply of high frequency power to the antenna 91 and the supply of processing gas from the gas supply unit 80 are stopped. In addition, the exhaust unit 130 is operated to exhaust the processing gas remaining in the substrate processing space S2.

[0065] Next, the substrates W that have been subjected to plasma processing are transferred from each stage 51, 52 to the wafer transfer mechanism 40 and are then transferred out of the processing vessel 60. The substrates W transferred out of the processing vessel 60 are transferred by the wafer transfer mechanism 40 to the load lock module 20, and then stored in the FOUP F placed on the load port 11 after being cooled in the cooling storage 12. Then, when the desired plasma processing is completed for all of the substrates W stored in the FOUP F and the last substrate W is stored in the FOUP F, the series of wafer processing steps in the vacuum processing system 1 is completed.

[0066] According to the plasma processing method of this embodiment, it is possible to adjust the current ratio or power ratio of each of the coils 101 to 104. Furthermore, it is possible to match the impedance between the high-frequency circuit 200 and the plasma while maintaining the desired current ratio or power ratio of the coils 101 to 104. This allows both optimal adjustment of the plasma distribution according to the desired process conditions and stable plasma generation, enabling flexible operation to change the plasma distribution.

[0067] <Antenna Modification> An antenna 220 according to a modification of the present embodiment will now be described. Fig. 5 is a plan view showing an outline of the configuration of the antenna 220 according to the modification. In the antenna 220 according to the modification, the second main coil 103 and the second sub-coil 104 are configured in a clockwise direction as shown in Fig. 5. The antenna 220 according to the modification also has a high-frequency circuit 200 similar to that shown in Fig. 4.

[0068] The antenna 220 according to the modified example can also achieve the same effects and advantages as those of the above-described embodiment, and can implement a similar plasma processing method. In the antenna 220 according to the modified example, to increase the plasma density at the center of the antenna, the positions of the variable capacitors 201 to 204 are controlled so that the impedances of the first and second systems and the impedances of the third and fourth systems are different, being inductive and capacitive. For example, the impedances of the first and second systems are inductive, and the impedances of the third and fourth systems are capacitive. This causes the induced electromotive forces generated by the currents in the coils 101 to 104 to reinforce each other, thereby increasing the plasma density at the center of the antenna.

[0069] <Another Modification of the Antenna> An antenna 230 according to another modification of the present embodiment will now be described. Fig. 6 is a plan view showing an outline of the configuration of the antenna 220 according to the modification. As shown in Fig. 6, the antenna 230 according to the modification is configured such that the first subcoil 102 is eccentric in a direction away from the second main coil 103 and the second subcoil 104, and the second subcoil 104 is eccentric in a direction away from the first main coil 101 and the second main coil 103. In other words, the first subcoil 102 and the second subcoil 104 are eccentrically disposed in a direction away from the center of the antenna. The antenna 220 according to the modification also has a high-frequency circuit 200 similar to that shown in Fig. 4.

[0070] The antenna 230 according to the modified example can also achieve the same functions and effects as those of the above embodiment, and can implement a similar plasma processing method.

[0071] In the above embodiment, when the substrate W on each stage 51, 52 and the first subcoil 102 and the second subcoil 104 are respectively arranged concentrically, a region of low plasma density occurs at the center of the first subcoil 102 and the second subcoil 104. Even if the substrate W placed on each stage 51, 52 is rotated in place in the horizontal direction, this region is located at the center of rotation of the substrate W, and therefore is not averaged within the plane of the substrate W. On the other hand, in the antenna 230 according to this modification, the first subcoil 102 and the second subcoil 104 are arranged eccentrically, so that the region of low plasma density is shifted from the center of rotation. As a result, by rotating the substrate W placed on each stage 51, 52 in place in the horizontal direction, the unevenness of the plasma density can be more evened out within the plane of the substrate W.

[0072] In the antenna 230 according to the modified example, it is preferable to make the impedances of the first to fourth systems inductive and control the plasma density at the center of the antenna to be high. This causes the first sub-coil 102 and the second sub-coil 104 to be eccentric so as to be away from the high-density region at the center of the antenna, and by rotating the substrate W placed on each stage 51, 52 in place in the horizontal direction, it is possible to more even out the unevenness in the plasma density within the plane of the substrate W. From this perspective, yet another modified example is also conceivable in which the first sub-coil 102 and the second sub-coil 104 are configured eccentrically so as to be closer to the center of the antenna and controlled so that the plasma density at the center of the antenna is low.

[0073] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0074] For example, in the above embodiment, one plasma processing apparatus 32 is configured to process two substrates W using two stages 51, 52. However, a configuration may be adopted in which more than two stages, for example, four stages, are used to process four substrates W. In this case, a single high-frequency power supply 93 may be connected to multiple sets of main coils and sub-coils provided above each stage. Alternatively, as in the above embodiment, one high-frequency power supply 93 may be connected to two sets of main coils and sub-coils (the set of the first main coil 101 and the first sub-coil 102, and the set of the second main coil 103 and the second sub-coil 104), and another high-frequency power supply 93 may be connected to the other two sets of main coils and sub-coils.

[0075] Furthermore, for example, the components of the above-described embodiments can be combined in any manner, and such combinations will naturally provide the functions and effects of the respective components involved in the combination, as well as other functions and effects that will be apparent to those skilled in the art from the description herein.

[0076] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects.

[0077] The following configuration examples also fall within the technical scope of the present disclosure: (1) A plasma processing apparatus comprising: a processing vessel; a first stage and a second stage disposed in an internal space of the processing vessel and on which a substrate is respectively placed; an antenna disposed outside the internal space and above the first and second stages; and a high-frequency power supply that supplies high-frequency power to the antenna, wherein a ceiling of the processing vessel is made of a dielectric material, and the internal space comprises a plasma generation space in which plasma is generated by an induced electromotive force from the antenna, and a substrate processing space in which the first and second stages are disposed, wherein the plasma generation space communicates with the area above the first stage and the area above the second stage, and the substrate processing space communicates with the area above the first stage and the area above the second stage. (2) The plasma processing apparatus according to (1), wherein the antenna includes: a first main coil and a first sub-coil arranged above the first stage; and a second main coil and a second sub-coil arranged above the second stage, wherein the first main coil is arranged radially outside the first sub-coil to surround the first sub-coil in a planar view, and the second main coil is arranged radially outside the second sub-coil to surround the second sub-coil in a planar view. (3) The plasma processing apparatus according to (2), wherein a single high-frequency power supply is provided in common for the first main coil, the first sub-coil, the second main coil, and the second sub-coil. (4) The plasma processing apparatus according to (2) or (3), wherein the first stage and the second stage include a rotation mechanism that rotates a mounting surface on which the substrate is mounted on each of the first stage and the second stage. (5) The plasma processing apparatus according to any one of (2) to (4), wherein, in a plan view of the antenna, the first main coil and the second main coil are arranged so that at least a part of their outer peripheries overlap. (6) The plasma processing apparatus according to any one of (2) to (5), wherein, in a plan view of the antenna, the first sub-coil and the second sub-coil are arranged eccentrically in a direction away from a center of the antenna.(7) The plasma processing apparatus according to any one of (2) to (6), wherein, in a plan view of the antenna, outer diameters of the first main coil and the second main coil are each larger than an outer diameter of the substrate. (8) The plasma processing apparatus according to any one of (2) to (7), comprising a power splitter connected to the antenna and configured to be able to individually adjust impedances of the first main coil, the first sub coil, the second main coil, and the second sub coil. (9) The plasma processing apparatus according to (8), wherein the power splitter comprises variable capacitors connected to the first main coil, the first sub coil, the second main coil, and the second sub coil, respectively. (10) The plasma processing apparatus according to (8) or (9), further comprising: a matching box connected between the high-frequency power supply and the antenna and configured to be capable of impedance matching between the high-frequency circuit including the high-frequency power supply, the antenna, and the power splitter and plasma; and a control unit, wherein the control unit executes control including performing the impedance matching in the matching box while maintaining a constant current ratio or power ratio of the first main coil, the first sub-coil, the second main coil, and the second sub-coil in the power splitter. (11) The plasma processing apparatus according to any one of (1) to (10), further comprising:(12) A plasma processing method for processing a substrate using a plasma processing apparatus, the plasma processing apparatus comprising: a processing vessel; a first stage and a second stage disposed in an internal space of the processing vessel and on which a substrate is respectively placed; an antenna including a first main coil and a first sub-coil disposed above the first stage and a second main coil and a second sub-coil disposed above the second stage; a single high-frequency power supply for supplying high-frequency power to the antenna; a power splitter connected to the antenna and configured to be able to individually adjust the impedances of the first main coil, the first sub-coil, the second main coil, and the second sub-coil; and a matching box connected between the antenna and the high-frequency power supply and configured to be able to match impedances between a high-frequency circuit including the antenna, the high-frequency power supply, and the power splitter and plasma; and the plasma processing method includes performing the impedance matching in the matching box while maintaining a constant current ratio or power ratio of the first main coil, the first sub-coil, the second main coil, and the second sub-coil in the power splitter.

[0078] 32 Plasma processing apparatus 51 First stage 52 Second stage 60 Processing container 62 Lid 91 Antenna 93 High frequency power supply W Substrate S1 Plasma generation space S2 Substrate processing space

Claims

1. A plasma processing apparatus comprising: a processing vessel; a first stage and a second stage disposed in the internal space of the processing vessel and on which substrates are respectively placed; an antenna disposed outside the internal space above the first stage and the second stage; and a high frequency power supply for supplying high frequency power to the antenna, wherein the ceiling of the processing vessel is made of a dielectric material; the internal space comprises a plasma generation space in which plasma is generated by induced electromotive force from the antenna, and a substrate processing space in which the first stage and the second stage are disposed; the plasma generation space is connected between the upper part of the first stage and the upper part of the second stage; and the substrate processing space is connected between the upper part of the first stage and the upper part of the second stage.

2. The plasma processing apparatus of claim 1, wherein the antenna comprises: a first main coil and a first sub-coil arranged above the first stage; and a second main coil and a second sub-coil arranged above the second stage, wherein the first main coil is arranged radially outside the first sub-coil so as to surround the first sub-coil in a planar view; and the second main coil is arranged radially outside the second sub-coil so as to surround the second sub-coil in a planar view.

3. The plasma processing apparatus according to claim 2, wherein the high frequency power supply is a single power supply commonly provided for the first main coil, the first sub-coil, the second main coil, and the second sub-coil.

4. The plasma processing apparatus according to claim 2, wherein the first stage and the second stage are provided with a rotation mechanism for rotating the mounting surfaces of the first stage and the second stage on which the substrate is mounted.

5. The plasma processing apparatus according to claim 4, wherein, in a plan view of the antenna, the first main coil and the second main coil are arranged so that at least a portion of their outer peripheries overlap.

6. The plasma processing apparatus according to claim 4, wherein, in a plan view of the antenna, the first sub-coil and the second sub-coil are eccentrically positioned in a direction away from the center of the antenna.

7. The plasma processing apparatus according to any one of claims 2 to 6, wherein, in a plan view of the antenna, the outer diameters of the first main coil and the second main coil are each larger than the outer diameter of the substrate.

8. A plasma processing apparatus according to any one of claims 2 to 6, further comprising a power splitter connected to the antenna and configured to be able to individually adjust the impedances of the first main coil, the first sub coil, the second main coil, and the second sub coil.

9. The plasma processing apparatus according to claim 8, wherein the power splitter comprises variable capacitors connected to the first main coil, the first sub-coil, the second main coil, and the second sub-coil, respectively.

10. A plasma processing apparatus as described in claim 8, comprising: a matching box connected between the high frequency power supply and the antenna and configured to enable impedance matching between the high frequency circuit including the high frequency power supply, the antenna, and the power splitter and plasma; and a control unit, wherein the control unit executes control including performing the impedance matching in the matching box while maintaining a constant current ratio or power ratio of the first main coil, the first sub-coil, the second main coil, and the second sub-coil in the power splitter.

11. The plasma processing apparatus according to any one of claims 1 to 6, wherein the antenna is embedded inside the dielectric member in the thickness direction.

12. A plasma processing method for processing a substrate using a plasma processing apparatus, the plasma processing apparatus comprising: a processing vessel; a first stage and a second stage disposed in the internal space of the processing vessel and on which a substrate is respectively placed; an antenna including a first main coil and a first sub-coil disposed above the first stage and a second main coil and a second sub-coil disposed above the second stage; a single high-frequency power supply for supplying high-frequency power to the antenna; a power splitter connected to the antenna and configured to be able to individually adjust the impedances of the first main coil, the first sub-coil, the second main coil, and the second sub-coil; and a matching box connected between the antenna and the high-frequency power supply and configured to be able to match the impedance of a high-frequency circuit including the antenna, the high-frequency power supply, and the power splitter with plasma, the plasma processing method comprising performing the impedance matching in the matching box while maintaining a constant current ratio or power ratio of the first main coil, the first sub-coil, the second main coil, and the second sub-coil in the power splitter.

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