Substrate processing apparatus and substrate processing method

Abstract

The present invention relates to a substrate processing apparatus and a substrate processing method. In the substrate processing apparatus, a nozzle supplies a processing liquid for etching toward an upper surface of a substrate from above the substrate, and brings it into contact with a processed film. A nozzle moving mechanism swings the nozzle horizontally above the substrate in rotation between a central portion of the substrate and a peripheral portion of the substrate. A first electrode is electrically connected to the substrate. A second electrode is electrically connected to the processing liquid ejected from the nozzle. A power supply portion performs application of a voltage between the first electrode and the second electrode. By control of a control portion, in a state where the processing liquid is continuously supplied from the nozzle toward the upper surface of the substrate, and a voltage is applied between the first electrode and the second electrode, a rotational speed of the substrate is repeatedly switched between a first rotational speed and a second rotational speed different from each other at a prescribed rotational speed switching period, with the nozzle swung above the substrate in rotation.

Description

[0001] [Reference to relevant applications] This application claims priority based on Japanese Patent Application JP2025-074557 filed on April 28, 2025, the entire contents of which are disclosed in that application and are incorporated herein by reference. Technical Field

[0002] This invention relates to a technique for etching a substrate. Background Technology

[0003] In the past, various processes were performed on semiconductor substrates (hereinafter referred to as "substrate") during the fabrication process. For example, wet etching is performed in the substrate fabrication process, that is, an etching solution is supplied to the substrate to remove the film on the substrate. It is known that in this wet etching, the etching rate of the film in the micro-recesses such as trenches and holes on the substrate is low.

[0004] Therefore, Japanese Patent Application Publication No. 2020-155614 (Document 1) proposes a technique in which a conductive etching solution is supplied to a substrate, and a fixed-magnitude direct current is applied between the etching solution and the substrate, thereby allowing the conductive components of the etching solution to rapidly enter the gaps within the microstructures. Furthermore, International Patent Publication No. 2021 / 192502 (Document 2) proposes a technique in which an alternating voltage of 0.1 kHz or 1 kHz is applied to a pair of electrodes positioned between a substrate in contact with the etching solution, thereby increasing the etching rate.

[0005] However, in the substrate etching process, a further increase in etching rate is required. This is especially true for etching films within fine recesses where the etching rate is significantly reduced in conventional etching methods. Summary of the Invention

[0006] The present invention relates to a substrate processing apparatus for etching a substrate, with the aim of increasing the etching rate.

[0007] Embodiment 1 of the present invention is a substrate processing apparatus for etching a substrate, comprising: a substrate holding section for holding a substrate having a film to be processed on its upper surface in a horizontal state; a substrate rotation mechanism for rotating the substrate holding section about a central axis in the vertical direction; a nozzle for supplying etching processing liquid from above the substrate toward the upper surface of the substrate and bringing it into contact with the film to be processed; a nozzle moving mechanism for oscillating the nozzle horizontally between the center and the periphery of the rotating substrate; a first electrode electrically connected to the substrate; a second electrode electrically connected to the processing liquid ejected from the nozzle; a power supply section for applying a voltage between the first electrode and the second electrode; and a control section for controlling the substrate rotation mechanism, the nozzle, and the power supply section. Under the control of the control unit, while the processing liquid is continuously supplied from the nozzle to the upper surface of the substrate and a voltage is applied between the first electrode and the second electrode, the rotational speed of the substrate repeatedly switches between different first and second rotational speeds at a predetermined rotational speed switching cycle, wherein the nozzle oscillates above the rotating substrate.

[0008] According to the present invention, the etching rate can be increased.

[0009] Embodiment 2 of the present invention is a substrate processing apparatus of Embodiment 1, wherein, under the control of the control unit, in parallel with the switching of the rotational speed of the substrate, the applied voltage is repeatedly switched between different first and second voltages at a predetermined voltage switching cycle, thereby repeatedly switching the potential of the sidewall surface of the recessed portion forming the pattern on the substrate between a first potential and a second potential less than the first potential. The first potential is 0 V or higher. The second potential is 0 V or lower.

[0010] The third aspect of the present invention is the substrate processing apparatus of aspect 2, wherein the voltage switching cycle is 0.05 seconds or more.

[0011] The fourth embodiment of the present invention is a substrate processing apparatus of the second embodiment (or the third embodiment), wherein the rotation speed switching period is an integer multiple of the voltage switching period.

[0012] The fifth embodiment of the present invention is the substrate processing apparatus of the fourth embodiment, wherein the rotation speed switching period is an even multiple of the voltage switching period.

[0013] The sixth embodiment of the present invention is a substrate processing apparatus of any one of embodiments 2 to 5, wherein the switching of the substrate rotation speed and the switching of the applied voltage are performed simultaneously under the control of the control unit.

[0014] Embodiment 7 of the present invention is a substrate processing method for etching a substrate, comprising the following steps: a) holding a substrate having a film to be processed on its upper surface in a horizontal position; b) continuously supplying an etching solution to the upper surface of the substrate from a nozzle, wherein the nozzle is positioned above the substrate rotating about a central axis in the vertical direction and oscillating horizontally between the center and periphery of the substrate; c) in parallel with step b), repeatedly switching the rotational speed of the substrate between a first rotational speed and a second rotational speed at a predetermined rotational speed switching cycle; and d) in parallel with step c), applying a voltage between the substrate and the etching solution ejected from the nozzle, and repeatedly switching the applied voltage between a first voltage and a second voltage at a predetermined voltage switching cycle, thereby causing the potential of the sidewall surface of the recesses forming the pattern on the substrate to repeatedly switch between a first potential and a second potential less than the first potential. The first potential is 0 V or higher. The second potential is 0 V or lower.

[0015] The objectives, other objectives, features, forms, and advantages of the present invention are set forth in the following detailed description with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a top view of the substrate processing system.

[0018] Figure 2 This is a side view of the substrate processing apparatus according to the first embodiment.

[0019] Figure 3 It is a diagram showing an enlarged view of the area near the clamping pin.

[0020] Figure 4 It is a cross-sectional view that is magnified and represents a portion of the substrate.

[0021] Figure 5 This is a diagram showing the substrate processing flow.

[0022] Figure 6 This is a side view of the substrate processing apparatus.

[0023] Figure 7 This is a diagram showing the switching of the substrate's rotational speed.

[0024] Figure 8A It is a diagram showing the waveform of the applied voltage.

[0025] Figure 8B It is a diagram showing the waveform of the applied voltage.

[0026] Figure 9AIt is a cross-sectional view that is magnified and represents a portion of the substrate.

[0027] Figure 9B It is a cross-sectional view that is magnified and represents a portion of the substrate.

[0028] Figure 9C It is a cross-sectional view that is magnified and represents a portion of the substrate.

[0029] Figure 9D It is a cross-sectional view that is magnified and represents a portion of the substrate.

[0030] Figure 10A It is a cross-sectional view that is magnified and represents a portion of the substrate.

[0031] Figure 10B It is a cross-sectional view that is magnified and represents a portion of the substrate.

[0032] Figure 10C It is a cross-sectional view that is magnified and represents a portion of the substrate.

[0033] Figure 10D It is a cross-sectional view that is magnified and represents a portion of the substrate.

[0034] Figure 11 This is a diagram showing the experimental setup.

[0035] Figure 12 It is a cross-sectional view that is magnified and represents a portion of the substrate.

[0036] Figure 13 This is a side view of another substrate processing device. Detailed Implementation

[0037] Figure 1 This is a schematic top view showing the layout of the substrate processing system 10. The substrate processing system 10 is a system for processing a semiconductor substrate 9 (hereinafter simply referred to as "substrate 9"). The substrate processing system 10 includes a transfer module 101 and a processing module 102 coupled to the transfer module 101.

[0038] The transfer module 101 includes a carrier holding section 104, a transfer robot 105, and an IR moving mechanism 106. The carrier holding section 104 holds multiple carriers 107 capable of accommodating multiple substrates 9. The multiple carriers 107 (e.g., FOUP) are held in the carrier holding section 104 in a state arranged along a predetermined carrier arrangement direction. The IR moving mechanism 106 moves the transfer robot 105 along the carrier arrangement direction. The transfer robot 105 performs a removal action to take the substrate 9 out of the carrier 107 and a loading action to load the substrate 9 into the carrier 107 held in the carrier holding section 104. The transfer robot 105 transfers the substrate 9 in a horizontal posture.

[0039] The processing module 102 includes multiple (e.g., four or more) processing units 108 for processing substrate 9, and a central robot 109. The multiple processing units 108 are arranged to surround the central robot 109 in a top-view configuration. Various processes are performed on the substrate 9 within the multiple processing units 108. The substrate processing apparatus described below is one of the multiple processing units 108. The central robot 109 performs a loading action to load the substrate 9 into the processing units 108 and a unloading action to remove the substrate 9 from the processing units 108. Furthermore, the central robot 109 transports the substrate 9 between the multiple processing units 108. The substrate 9 is transported horizontally by the central robot 109. The central robot 109 receives the substrate 9 from the transfer robot 105 and also delivers the substrate 9 to the transfer robot 105.

[0040] Figure 2 This is a side view showing the configuration of the substrate processing apparatus 1 according to the first embodiment of the present invention. The substrate processing apparatus 1 is a monolithic apparatus for processing substrates 9 one by one. The substrate processing apparatus 1 is an apparatus for etching the film to be processed provided on the upper main surface (hereinafter also referred to as "upper surface 91") of the substrate 9. Figure 2 In the image, a portion of the substrate processing apparatus 1 is shown in cross-section.

[0041] The substrate processing apparatus 1 includes a substrate holding section 21, a substrate rotation mechanism 23, a cup section 4, a processing liquid supply section 5, a voltage application section 6, a housing 11, and a control section 8. The substrate holding section 21, the substrate rotation mechanism 23, and the cup section 4 are housed within the internal space of the housing 11. An airflow forming section 12 is provided on the top cover of the housing 11 to supply gas to the internal space, forming a downward airflow (so-called downflow). For example, an FFU (fan filter unit) is used as the airflow forming section 12. The control section 8 is located outside the housing 11 and controls the substrate holding section 21, the substrate rotation mechanism 23, the processing liquid supply section 5, and the voltage application section 6.

[0042] The control unit 8 is, for example, a general-purpose computer system including a CPU, ROM, RAM, hard disk, display, input unit, reading device, communication unit, and bus. The processor, such as the CPU, executes calculations and other processing according to instructions stored in memory such as ROM, RAM, and hard disk. The control unit 8 includes a power control unit 81 and an operation control unit 82 to perform the functions implemented by the processor. The power control unit 81 controls the power supply unit 63 (described below) of the voltage application unit 6. The operation control unit 82 controls the processing liquid supply unit 5 and the substrate rotation mechanism 23, etc. Alternatively, the control unit 8 can also be a programmable logic controller (PLC) or a circuit board. The control unit 8 can also include any combination of computer systems, PLCs, and circuit boards.

[0043] The substrate holding part 21 and the substrate rotating mechanism 23 are both parts of a rotating chuck that holds and rotates a generally circular substrate 9. The substrate holding part 21 supports the horizontally positioned substrate 9 from below. Figure 2 The substrate holding section 21 shown is a mechanical clamp that holds the substrate 9 mechanically.

[0044] The substrate holding portion 21 includes a base portion 211, a plurality of (e.g., 4 or 6) clamping pins 212, and a shaft 217. The base portion 211 is a generally circular plate-shaped component centered on a central axis J1 pointing vertically. The substrate 9 is disposed above the base portion 211, separated from it. In other words, the base portion 211 of the substrate holding portion 21 faces the lower surface 92 (hereinafter also referred to as "lower surface 92") vertically, separated from the lower side main surface of the substrate 9. The diameter of the base portion 211 is slightly larger than the diameter of the substrate 9. The shaft 217 is a generally cylindrical or generally cylindrical component centered on the central axis J1. The shaft 217 extends vertically and is connected to the center of the lower surface of the base portion 211.

[0045] In the substrate holding portion 21, a plurality of clamping pins 212 are arranged circumferentially (hereinafter also simply referred to as "circumferential") around the central axis J1 and erected on the outer periphery of the upper surface of the base portion 211. The plurality of clamping pins 212 are located at approximately the same position radially (hereinafter also simply referred to as "radial") around the central axis J1. In other words, the plurality of clamping pins 212 are located on approximately the same circumference around the central axis J1. The plurality of clamping pins 212 are arranged, for example, at approximately equal angular intervals in the circumferential direction. The plurality of clamping pins 212 contact the periphery of the substrate 9 to hold the substrate 9.

[0046] Figure 3 This is an enlarged view of the area near a clamping pin 212 on the base portion 211. The shape of the plurality of clamping pins 212 is similar to... Figure 3 The illustrated shapes are generally the same. The radially inner side surface of the upper part of the clamping pin 212 (hereinafter also referred to as "upper inner side surface 213") is in direct contact with the periphery of the substrate 9. In the clamping pin 212, the central portion 214 of the upper inner side surface 213 in the vertical direction is recessed radially outward. In other words, the central portion 214 of the upper inner side surface 213 of the clamping pin 212 is located radially outward compared to the upper portion 215 above the central portion 214 and the lower portion 216 below the central portion 214. When the substrate 9 is held by the substrate holding portion 21, the upper portion 215 of the upper inner side surface 213 of the clamping pin 212 is in direct contact with the periphery of the upper surface 91 of the substrate 9, and the lower portion 216 of the upper inner side surface 213 of the clamping pin 212 is in direct contact with the periphery of the lower surface 92 of the substrate 9.

[0047] like Figure 2 As shown, the substrate rotation mechanism 23 is disposed inside the cover portion 24 located below the substrate holding portion 21. The cover portion 24 is a covered, generally cylindrical component centered on the central axis J1. The upper surface of the cover portion 24 is separated from the lower surface of the base portion 211 and faces each other in the vertical direction. A small gap is provided between the upper surface of the cover portion 24 and the lower surface of the base portion 211.

[0048] The substrate rotation mechanism 23 rotates the substrate 9 together with the substrate holding portion 21 around a central axis J1 that extends substantially parallel to the vertical direction. The substrate rotation mechanism 23 includes a motor 232. The motor 232 is an electric rotary motor that rotates the shaft 217 of the substrate holding portion 21. Alternatively, the substrate rotation mechanism 23 may also be a motor with other structures (e.g., a hollow motor).

[0049] The processing solution supply unit 5 supplies processing solution to the substrate 9. Figure 2 In the example shown, the processing liquid supply unit 5 includes a nozzle 51. The nozzle 51 is located above the substrate 9, separated from the upper surface 91 of the substrate 9. The nozzle 51 can spray processing liquid onto the upper surface 91 of the substrate 9. The processing liquid sprayed from the nozzle 51 contacts the film to be processed disposed on the upper surface 91 of the substrate 9.

[0050] The nozzle 51 is supported above the substrate 9 by a generally horizontally extending arm 53. The nozzle 51 is a generally cylindrical tubular component extending generally parallel to the vertical direction. The end of the arm 53 opposite to the nozzle 51 is connected to a nozzle moving mechanism 55. The nozzle moving mechanism 55 moves the nozzle 51 horizontally by rotating the arm 53 horizontally. The nozzle 51 can move, for example, between a position above the substrate 9 and a retracted position radially outward from the periphery of the substrate 9. Additionally, the nozzle moving mechanism 55 raises and lowers the nozzle 51 by moving the arm 53 vertically. The nozzle moving mechanism 55 can be, for example, a ball screw or an electric rotary motor. The nozzle moving mechanism 55 can also be an electric rotary motor, an electric linear motor, or a cylinder, etc.

[0051] The processing liquid supplied from nozzle 51 to the upper surface 91 of substrate 9 is, for example, a liquid (i.e., an etching solution) used to etch the film to be processed disposed on the upper surface 91 of substrate 9. This processing liquid is generally conductive. The etching solution contains etchants such as hydrogen peroxide (H2O2), hydrofluoric acid (HF), nitric acid (HNO3), ammonia (NH3), TMAH (tetramethylammonium hydroxide), or TBAH (tetrabutylammonium hydroxide).

[0052] Nozzle 51 can also spray a processing liquid (i.e., rinsing solution) for rinsing the upper surface 91 of substrate 9. DIW (deionized water) or similar solutions can be used as the rinsing solution. Additionally, nozzle 51 can also spray processing liquids other than etching solutions and rinsing solutions, and / or inactive gases such as nitrogen (N2).

[0053] The cup portion 4 includes a cup 41 and a cup lifting mechanism (not shown in the figure). The cup 41 is an annular component centered on the central axis J1. The cup 41 is arranged across the entire circumference of the substrate 9 and the substrate holding portion 21, covering the sides and bottom of the substrate 9 and the substrate holding portion 21. The cup 41 is a liquid receiving container for receiving liquids such as processing liquid that are scattered from the rotating substrate 9. The inner surface of the cup 41 is formed, for example, by a water-repellent material. The cup 41 remains stationary in the circumferential direction regardless of whether the substrate 9 is rotating or stationary. At the bottom of the cup 41, a drain port (not shown in the figure) is provided for discharging the processing liquid or the like received in the cup 41 to the outside of the outer casing 11.

[0054] The cup-holding lifting mechanism causes the cup 41 to move vertically relative to the substrate holding part 21. The cup-holding lifting mechanism can be, for example, an electric linear motor, a cylinder, or a ball screw and electric rotary motor connected to the cup 41. Through the cup-holding lifting mechanism, the cup 41 can... Figure 2 The processing position shown is located around the substrate 9 and moves vertically between the processing position and the retreat position located below the processing position.

[0055] The cup portion 4 may also have multiple cups 41 stacked radially. When the cup portion 4 has multiple cups 41, the multiple cups 41 can move independently in the vertical direction, and the multiple cups 41 can be switched to receive the processing liquid depending on the type of processing liquid that is dispersed from the substrate 9.

[0056] The voltage application unit 6 includes a first electrode 61, a second electrode 62, a power supply unit 63, a first transmission unit 64, and a second transmission unit 65. The first electrode 61 is provided on each clamping pin 212 of the substrate holding unit 21. Specifically, as shown... Figure 3 As shown, the first electrode 61 is a generally plate-shaped conductive component disposed on the upper inner surface 213 of the clamping pin 212. The radially inner surface of the first electrode 61 protrudes from the upper inner surface 213 of the clamping pin 212 and is not covered by the clamping pin 212.

[0057] The first electrode 61 is disposed on the upper inner side 213 of the clamping pin 212, spanning the upper part 215, the central part 214 and the lower part 216 of the upper inner side 213. The first electrode 61 is electrically connected to the substrate 9 by directly contacting the peripheral part of the substrate 9. Figure 3In the example shown, the first electrode 61 is located at the periphery of the substrate 9 and is in direct contact with both the upper surface 91 and the lower surface 92 of the substrate 9.

[0058] The multiple first electrodes 61, each disposed on a plurality of clamping pins 212, are formed of a material with high chemical resistance and conductivity. Each first electrode 61 is formed, for example, of platinum (Pt) or glassy carbon (GC). Furthermore, the shape and material of each first electrode 61 can be varied. The surface of each clamping pin 212, other than the first electrode 61, is formed of, for example, an insulator. This surface can also be formed of a conductor.

[0059] The second electrode 62 is electrically connected to the treatment liquid ejected from the nozzle 51. Figure 2 In the example shown, the second electrode 62 is disposed inside the nozzle 51 and is in direct contact with the processing liquid flowing through the flow path inside the nozzle 51, and is electrically connected to the processing liquid. Thus, the second electrode 62 is electrically connected to the processing liquid ejected from the nozzle 51 before the processing liquid exits the nozzle 51. The second electrode 62 is formed of a material with high chemical resistance and electrical conductivity. For example, the second electrode 62 is formed of platinum (Pt) or glassy carbon (GC). Furthermore, the material and arrangement of the second electrode 62 can be varied.

[0060] The second electrode 62 does not necessarily need to be located inside the nozzle 51. For example, if the nozzle 51 is made of a highly conductive material such as glassy carbon, the second electrode 62 may be disposed in direct contact with the surface of the nozzle 51. Thus, the second electrode 62 and the treatment liquid ejected from the nozzle 51 are electrically connected via the nozzle 51 before the treatment liquid is ejected from the nozzle 51.

[0061] Alternatively, if the piping 511 is a conductive pipe such as an AS (Anti-Static) pipe, the second electrode 62 can also be disposed in direct contact with the surface of the piping 511. In this case, the second electrode 62 is electrically connected to the treatment liquid ejected from the nozzle 51 via the piping 511 before the treatment liquid is ejected from the nozzle 51. Various changes can be made to the materials of the nozzle 51 and the piping 511.

[0062] Furthermore, if the nozzle 51 and the piping 511 are conductive, the second electrode 62 can be electrically connected to at least one of the nozzle 51 and the piping 511. Alternatively, if the nozzle 51 is conductive, the nozzle 51 can also be used as the second electrode 62. Additionally, if the piping 511 is conductive, the piping 511 can also be used as the second electrode 62.

[0063] The power supply unit 63 is electrically connected to the first electrode 61 and the second electrode 62, and applies a voltage between the first electrode 61 and the second electrode 62. In the following description, the voltage applied between the first electrode 61 and the second electrode 62 via the power supply unit 63 will also be referred to as the "applied voltage". For example, a power source capable of applying both DC and AC voltages can be used as the power supply unit 63. The power supply unit 63 is controlled by the power control unit 81 of the control unit 8.

[0064] Figure 2 In the example shown, the power supply unit 63 is mechanically and electrically connected to the second electrode 62 via wires. Additionally, the power supply unit 63 is electrically connected to each of the first electrodes 61 via the second transmission unit 65 and the first transmission unit 64. The first transmission unit 64 is disposed in the base portion 211 of the substrate holding portion 21. Specifically, the first transmission unit 64 is disposed inside the base portion 211, for example, near the lower surface of the base portion 211. The first transmission unit 64 rotates with the substrate holding portion 21 when the substrate holding portion 21 rotates. The first transmission unit 64 is a generally annular plate-shaped receiving substrate centered on the central axis J1. A receiving coil is provided on the lower surface of the first transmission unit 64, and circuit components for receiving electricity are mounted on the upper surface of the first transmission unit 64. The first transmission unit 64 is mechanically and electrically connected to each of the first electrodes 61 via wires disposed inside the base portion 211.

[0065] The second transmission section 65 is located inside the cover section 24, near the upper surface of the cover section 24. That is, the second transmission section 65 is arranged downwards, separated from the base section 211 of the substrate holding section 21. The second transmission section 65 remains stationary independently of the rotation of the substrate holding section 21 when the substrate holding section 21 rotates. The second transmission section 65 is, for example, a generally annular plate-shaped power transmission substrate centered on a central axis J1. The second transmission section 65 is separated from the first transmission section 64 and faces each other in the vertical direction. The shape of the second transmission section 65 in plan view is, for example, substantially the same as the shape of the first transmission section 64 in plan view. A power transmission coil is provided on the upper surface of the second transmission section 65, and circuit components for power transmission are mounted on the lower surface of the second transmission section 65. The second transmission section 65 is mechanically and electrically connected to the power supply section 63 via wires.

[0066] When a voltage is applied between the first electrode 61 and the second electrode 62 via the power supply unit 63, the transmitting coil of the second transmission unit 65 is magnetically coupled to the receiving coil of the first transmission unit 64, and power is transmitted from the second transmission unit 65 to the first transmission unit 64 in a contactless manner. That is, the first transmission unit 64 and the second transmission unit 65 are magnetically coupled wireless feeding elements. Furthermore, the shape, structure, and arrangement of the first transmission unit 64 and the second transmission unit 65 can be varied. For example, the first transmission unit 64 and the second transmission unit 65 can also be electric field coupled wireless feeding elements.

[0067] Figure 4 This is a cross-sectional view showing an enlarged portion of substrate 9. Figure 4 In the example shown, two of the many microstructures 94 constituting the micropattern (hereinafter also referred to as "micropattern 93") disposed on the surface of the substrate 9 are shown. The microstructure 94 is a microstructure disposed on the upper surface of the substrate body formed of silicon (Si), for example, it can be a structure formed of a single material or a multilayer structure formed by stacking multiple materials.

[0068] The microstructure 94 is, for example, a nanosheet channel with a GAA (Gate All Around) structure, and the recess 95 is a trench between these nanosheet channels. The processed film 96 is a metal gate electrode material in an RMG (Replacement Metal Gate). The sidewall surface 942 of the microstructure 94 forming the recess 95 (i.e., the inner surface of the recess 95) is formed, for example, from a High-k material (high dielectric constant material) with a higher dielectric constant than SiO2 (silicon dioxide). Hafnium-based, tungsten-based, or cobalt-based materials can be used as the High-k material.

[0069] The two microstructures 94 are along with Figure 4 The paper extends in a roughly straight line in a direction approximately perpendicular to the surface (hereinafter also referred to as the "length direction"). That is, in Figure 4 The image shows a longitudinal section of two microstructures 94, and also shows a longitudinal section of a micro-gap, i.e., a recess 95, provided between the two microstructures 94.

[0070] The width direction of the recess 95 perpendicular to the length direction (i.e., Figure 4 The width (in the vertical direction) is, for example, less than 10 nm. Figure 4 The depth of the recess 95 in the left-right direction is, for example, 20 nm or more. In addition, the ratio of the depth to the width of the recess 95, that is, the depth-to-width ratio (i.e., the value obtained by dividing the depth of the recess 95 by the width), is, for example, 5 or more.

[0071] Furthermore, the recess 95 can also be a recess other than a groove, such as a roughly circular hole when viewed from above. When the recess 95 is a hole, the width of the recess 95 is the diameter of the hole when viewed from above.

[0072] exist Figure 4The image shows a substrate 9 before etching by the substrate processing apparatus 1. In the substrate 9 before etching, the interior of the recess 95 and the end faces 941 of the two microstructures 94 are covered by a film 96 to be processed. The film 96 is, for example, a conductive film formed of a conductor. The film 96 is, for example, a metal film containing one or more metals selected from titanium (Ti), tantalum (Ta), tungsten (W), copper (Cu), and aluminum (Al). The film 96 contains, for example, at least one of TiN (titanium nitride), TaN (tantalum nitride), TiAl (titanium aluminum), and TiAlC (titanium aluminum carbide). Furthermore, the film 96 may also be formed from a material other than the aforementioned materials (e.g., MnO). The thickness of the film 96 on the end faces 941 of the microstructures 94 (i.e., the thickness of the film 96) is... Figure 4 The thickness in the left and right directions is, for example, more than 1 nm and less than 5 nm.

[0073] Next, refer to Figure 5 and Figure 6 The processing flow of substrate 9 in substrate processing apparatus 1 is described. Figure 5 This is a diagram showing the processing flow of substrate 9. Figure 6 This is a side view of the substrate processing apparatus 1 during the processing of substrate 9.

[0074] When processing substrate 9, firstly, as... Figure 2 As shown, the substrate 9 is moved into the substrate processing apparatus 1 and held in a generally horizontal position by the substrate holding part 21 (step S11). Thus, the first electrode 61 provided on each clamping pin 212 is in direct contact with the substrate 9 and electrically connected. During the movement of the substrate 9 in step S11, the nozzle 51 is in the retracted position.

[0075] After the substrate 9 is held by the substrate holding part 21, the nozzle moving mechanism 55 is controlled by the operation control part 82 of the control part 8, thereby causing the nozzle 51 to move horizontally, as... Figure 6 As shown, it is located above the substrate 9. For example, the nozzle 51 is located above the central portion of the substrate 9 (i.e., the radially central portion of the substrate 9).

[0076] Next, the substrate rotation mechanism 23 is driven by the motion control unit 82 of the control unit 8, thereby initiating the rotation of the substrate 9. Additionally, the processing liquid supply unit 5 is controlled by the motion control unit 82, thereby continuously supplying the etching processing liquid from the nozzle 51 to the upper surface 91 of the substrate 9. This processing liquid utilizes the centrifugal force generated by the rotation of the substrate 9 to diffuse across the entire upper surface 91 of the substrate 9, and interacts with the film 96 to be processed on the substrate 9 (see reference). Figure 4 Contact (step S12).

[0077] In this embodiment, the film 96 to be treated is a conductive film formed of titanium nitride (TiN), and the sidewall surface 942 of the microstructure 94 (refer to...) Figure 4 The solution used is hafnium oxide (HfO2). The treatment solution is a conductive liquid formed by adding an electrolyte to hydrogen peroxide water, which is used as an etching solution. The resistivity of this treatment solution is, for example, 0.1 Ω·m or less, preferably 0.05 Ω·m or less. As the electrolyte, for example, aqueous solutions of hydrochloric acid (HCl), sulfuric acid (H2SO4), ammonia, etc., can be used. Furthermore, the resistivity of the treatment solution can also be greater than 0.1 Ω·m. Alternatively, the treatment solution can be pure hydrogen peroxide water without the addition of hydrochloric acid, etc. The treatment solution can also be a mixed solution of hydrogen peroxide water and hydrochloric acid aqueous solution, i.e., SC2.

[0078] In step S12, approximately the entire upper surface 91 of the substrate 9 is covered with the etching solution. The processing solution supplied to the substrate 9 is dispersed radially outward from the periphery of the substrate 9 by the centrifugal force generated by the rotation of the substrate 9, and is received by the cup portion 4. The rotational speed of the substrate 9 in step S12 is, for example, 10 rpm or more, preferably 100 rpm to 3000 rpm, and more preferably 300 rpm to 1500 rpm.

[0079] In step S12, the nozzle moving mechanism 55 is controlled by the motion control unit 82, thereby causing the nozzle 51 to swing horizontally above the rotating substrate 9. For example, in top view, the nozzle 51 moves back and forth between the center of the substrate 9 (i.e., near the central axis J1) and the periphery of the substrate 9. Alternatively, in top view, the nozzle 51 moves back and forth along a path from one point on the periphery of the substrate 9, through the center of the substrate 9, to another point on the periphery of the substrate 9. That is, in top view, the nozzle 51 swings approximately horizontally between at least the center and the periphery of the substrate 9.

[0080] When the nozzle 51 moves back and forth between the center and the periphery of the substrate 9, the oscillation period of the nozzle 51 (i.e., the time required for one round trip) is, for example, 15 seconds to 2700 seconds. When the nozzle 51 moves back and forth between the periphery of the substrate 9, the oscillation period is, for example, 30 seconds to 5400 seconds.

[0081] In the substrate processing apparatus 1, in parallel with the supply of processing liquid in step S12, the substrate rotation mechanism 23 is controlled by the action control unit 82, thereby switching the rotational speed of the substrate holding unit 21 and the substrate 9. Specifically, the rotational speed of the substrate 9 repeatedly switches between two different first and second rotational speeds at a predetermined rotational speed switching cycle (step S13). The first rotational speed is, for example, 300 rpm to 600 rpm. The second rotational speed is greater than the first rotational speed, for example, 600 rpm to 1500 rpm. In step S13, the acceleration and deceleration of the substrate 9 rotational speed repeatedly alternate between the first and second rotational speeds. The absolute value of the rotational acceleration of the substrate 9 is, for example, 3000 rpm / s or more. The absolute value of the rotational acceleration of the substrate 9 is, for example, 15000 rpm / s or less, preferably 12500 rpm or less.

[0082] Figure 7 This is a diagram showing the acceleration and deceleration of the rotation of the substrate 9 in step S13. Figure 7 In the example shown, the first speed is 300 rpm and the second speed is 900 rpm. The absolute value of the rotational acceleration when accelerating from the first speed to the second speed and when decelerating from the second speed to the first speed is, for example, 9000 rpm / s. The speed switching period T... R For example, the time interval is 2 to 10 seconds, preferably 4 to 10 seconds. During each cycle T of the speed switching... R The substrate 9 is rotated at a first rotational speed for a specified time, and then at a second rotational speed for a specified time. The duration of each rotational speed is, for example, 2 to 5 seconds.

[0083] In addition, the first rotational speed, the second rotational speed, the rotational acceleration, the duration of holding the first and second rotational speeds, and the rotational speed switching period T. R The values ​​or ranges are not limited to those values ​​and can be varied. For example, the duration of each of the first and second rotational speeds can be 0 seconds. In addition, in step S13, there may be an instant when the rotational speed of the substrate 9 is 0 rpm, and the substrate 9 can be rotated in the reverse direction in the circumferential direction by switching the rotational speed.

[0084] On the rotating substrate 9, there exists a recess 95 (see reference). Figure 4 The processing liquid inside the recess 95 is restricted in its movement due to the fine structure 94, and moves circumferentially along with the substrate 9 at a speed approximately the same as the rotational speed of the substrate 9. On the other hand, the processing liquid existing on the upper surface 91 of the substrate 9 outside the recess 95 is not substantially restricted in its movement due to the fine structure 94. Therefore, during the acceleration and deceleration of the rotation of the substrate 9, the circumferential movement speed of the processing liquid outside the recess 95 is affected by inertia and deviates from the rotational speed of the substrate 9.

[0085] Thus, during the acceleration and deceleration of the substrate 9's rotation, a difference in circumferential movement speed arises between the processing liquid inside the recess 95 and the processing liquid above the recess 95 (i.e., the processing liquid located vertically above and outside the recess 95). As a result, vortices are generated in the upper part of the recess 95. These vortices, for example, move in a direction perpendicular to the depth of the recess 95 (i.e., Figure 4 A vortex is centered on an axis that is approximately perpendicular to the left-right direction of the recess 95. If a vortex is generated in the upper part of the recess 95, the flow of the processing liquid caused by the vortex is transferred downward, thereby causing the processing liquid to flow within the recess 95. As a result, the new processing liquid becomes easier to contact the sidewall surface 942 of the microstructure 94, and therefore, the etching rate of the film 96 being processed within the recess 95 increases.

[0086] In the substrate processing apparatus 1, in parallel with the supply of the processing liquid in step S12 and the switching of the rotation speed in step S13, the power supply unit 63 is controlled by the power control unit 81 of the control unit 8 to apply a voltage between the first electrode 61 and the second electrode 62. Thus, the voltage is applied through the processing liquid on the substrate 9 to the substrate 9 and the second electrode 62, which are electrically connected to the first electrode 61. In other words, the substrate 9 and the second electrode 62 are a pair of electrodes separated by the processing liquid, and a voltage is applied between these electrodes.

[0087] The applied voltage between the first electrode 61 and the second electrode 62 is controlled by the power supply control unit 81, and is repeatedly switched between different first and second voltages at a predetermined voltage switching cycle. Thus, the sidewall surface 942 of the microstructure 94 (refer to...) Figure 4 The potential of the voltage is repeatedly switched between the first potential and the second potential according to the voltage switching cycle (step S14).

[0088] The power supply unit 63 applies a voltage to the first electrode 61 based on the potential of the second electrode 62. Both the first and second potentials are based on the second electrode 62. The first potential is 0 V or higher. The second potential is 0 V or lower than the first potential. Therefore, when the first potential is 0 V, the second potential is less than 0 V. The first potential is, for example, +8 V or lower. The second potential is, for example, -8 V or higher. The upper limit of the first potential and the lower limit of the second potential can be varied.

[0089] The voltage switching period is preferably 0.05 seconds or more. The voltage switching period is preferably 20 seconds or less. When the applied voltage is a DC voltage, the voltage switching period is preferably 0.5 seconds or more, more preferably 1 second or more, and even more preferably 2 seconds or more. Furthermore, when the applied voltage is a DC voltage, the voltage switching period is preferably 18 seconds or less, more preferably 12 seconds or less, and even more preferably 6 seconds or less.

[0090] When the applied voltage is AC, a voltage switching period of 0.05 seconds or more corresponds to a frequency of 20 Hz or less, and a voltage switching period of 20 seconds or less corresponds to a frequency of 0.05 Hz or more. When the applied voltage is AC, the voltage switching period is preferably 0.1 seconds or more (i.e., a frequency of 10 Hz or less), more preferably 0.2 seconds or more (i.e., a frequency of 5 Hz or less). When the applied voltage is AC, the voltage switching period is preferably 2 seconds or less (i.e., a frequency of 0.5 Hz or more), more preferably 1 second or less (i.e., a frequency of 1 Hz or more).

[0091] The voltage switching period in step S14 is shorter than the oscillation period of the nozzle 51. This oscillation period is, for example, 300 to 600 times the voltage switching period. Alternatively, the voltage switching period is, for example, less than or equal to the rotational speed switching period. This rotational speed switching period is preferably an integer multiple of the voltage switching period (i.e., 1 or 2 times or more), and more preferably an even multiple of the voltage switching period. The switching of the substrate 9's rotational speed in step S13 (i.e., the start of acceleration or deceleration of the substrate 9's rotation) occurs approximately simultaneously with the switching of the applied voltage in step S14. Furthermore, the voltage switching period may also be longer than the rotational speed switching period.

[0092] The switching of the rotational speed of the substrate 9 in step S13 and the switching of the applied voltage in step S14 (i.e., the switching of the potential of the sidewall surface 942) are performed in parallel with the supply of processing liquid to the rotating substrate 9 and are carried out continuously for a predetermined time. As such, the film 96 to be processed on the substrate 9 is etched (so-called electrolytic etching) as described above.

[0093] Figure 8A and Figure 8B This is a diagram showing an example of the waveform of the applied voltage applied from the power supply unit 63 in step S14. Figure 8A This is an example of a waveform when a DC voltage is applied. Figure 8B This is an example of a waveform when an AC voltage is applied. Figure 8A and Figure 8B The horizontal axis represents elapsed time, and the vertical axis represents the applied voltage between the first electrode 61 and the second electrode 62. In this specification, the applied voltage is set to positive when the potential of the first electrode 61 is higher than the potential of the second electrode 62, and the applied voltage is set to negative when the potential of the first electrode 61 is lower than the potential of the second electrode 62. In the following description, when the applied voltage is positive, it will be stated as "a positive voltage is applied to the first electrode 61", and when the applied voltage is negative, it will be stated as "a negative voltage is applied to the first electrode 61".

[0094] Figure 8AIn the example shown, the applied voltage waveform is a rectangular wave. The maximum applied voltage (i.e., the first voltage) is +8 V, and the minimum applied voltage (i.e., the second voltage) is -8 V. As described above, the applied voltage is applied at a specified voltage switching period T. D The voltage repeatedly switches between the first voltage and the second voltage. In the following description, the voltage switching period T during each applied voltage period... D The time during which a positive voltage is applied is also called the "first application time T". Dp The time during which a negative voltage is applied is also called the "second application time T". Dm ". Figure 8A In the example shown, the first application time T Dp With the second application time T Dm Same, T D / 2. Furthermore, the first and second voltages can be appropriately varied, and their absolute values ​​do not need to be the same. Additionally, the first application time T... Dp With the second application time T Dm They don't have to be the same; they can also be different.

[0095] Figure 8B This is an example of a waveform when an AC voltage is applied. Figure 8B In the example shown, the waveform of the AC voltage is a sine wave. Figure 8B The vertical axis represents the instantaneous value of the applied voltage. The maximum applied voltage (i.e., the first voltage) is +8 V, and the minimum applied voltage (i.e., the second voltage) is -8 V. As described above, the applied voltage is applied at a specified voltage switching period T. A The voltage repeatedly switches between the first voltage and the second voltage. In the following description, the voltage switching period T during each applied voltage period... A The time during which a positive voltage is applied is also called the "first application time T". Ap The time during which a negative voltage is applied is also called the "second application time T". Am ". Figure 8B In the example shown, the first application time T Ap With the second application time T Am Same, T A / 2. Furthermore, the first and second voltages can be appropriately varied, and their absolute values ​​do not need to be the same. Additionally, the first application time T... Ap With the second application time T Am They don't necessarily have to be the same; they can also be different. When the applied voltage is an alternating current voltage, the waveform of the applied voltage is not limited to a sine wave; for example, it can also be a triangular wave or a sawtooth wave.

[0096] In step S14, the power supply unit 63 is controlled by the power supply control unit 81, causing the applied voltage to repeatedly switch between a first voltage and a second voltage. This promotes the etching of the film 96 to be processed, thereby increasing the etching rate. In particular, it promotes the etching of the film 96 to be processed within the recess 95, thereby increasing the etching rate.

[0097] The principle behind increasing the etching rate of the film 96 within the recess 95 by repeatedly switching the applied voltage is not rigorously defined. Several alternative principles considered as such are explained below.

[0098] First, refer to and Figure 4 Roughly the same sectional view, i.e. Figures 9A to 9D The first principle will be explained. Figures 9A to 9D The situation shown is that, Figure 4 The etching of the treated film 96 shown progresses to some extent; the treated film 96 on the end face 941 of the microstructure 94 is removed, and the treated film 96 inside the recess 95 is also slightly removed. Additionally, in Figures 9A to 9D In the diagram, for simplicity, the surface of the treated film 96 (i.e., the end face opposite to the bottom of the recess 95, i.e., the face on the left side of the diagram) is schematically drawn as being perpendicular to the left-right direction. The following... Figures 10A to 10D The same applies to China. Furthermore, Figures 9A to 9D In the example shown, the etching solution contains hydrogen peroxide as an etchant.

[0099] exist Figure 9A In the diagram, the first electrode 61 (reference) is shown. Figure 2 A positive voltage is applied. By applying a positive voltage to the first electrode 61, the surface of the film 96 to be treated within the recess 95 becomes positively charged. Additionally, the sidewall surfaces 942 (i.e., the inner surfaces of the recess 95) and end faces 941 of the two microstructures 94 located on either side of the recess 95 also become positively charged. Therefore, hydrogen peroxide molecules 71 and water molecules 72, which are polar molecules (also called polarized molecules), are adsorbed onto the surface of the film 96 to be treated, and onto the surface of the microstructures 94 (i.e., the sidewall surfaces 942 and end faces 941). Specifically, the negatively charged portions of the hydrogen peroxide molecules 71 and the negatively charged portions of the water molecules 72 are adsorbed onto the surfaces of the film 96 to be treated and the microstructures 94.

[0100] exist Figure 9AIn the diagram, hydrogen peroxide molecules 71 are schematically represented by circles, and arrows inside these circles indicate the charge concentration of hydrogen peroxide molecules 71. Specifically, the head (i.e., the arrowhead) of the arrow indicates the location of positive charge concentration in hydrogen peroxide molecules 71, and the end of the arrow opposite to the head indicates the location of negative charge concentration. Water molecules 72 are treated in a similar manner. Furthermore, the circle schematically representing water molecules 72 is drawn smaller than the circle schematically representing hydrogen peroxide molecules 71. Figure 9B and Figure 9D The same applies to China.

[0101] When a positive voltage is applied to the first electrode 61, the treated film 96 is etched by hydrogen peroxide molecules 71 adsorbed on the surface of the treated film 96. Furthermore, the hydrogen peroxide molecules 71 used to etch the treated film 96 are converted into hydroxide ions (OH-). - Hydrogen peroxide molecules 71 disappear from the surface of the treated film 96 as etching of the treated film 96 progresses. Consequently, hydrogen peroxide molecules 71 decrease or disappear on the surface of the treated film 96 and in the area near the treated film 96 (i.e., the inner surface of the recess 95) of the microstructure 94. Figure 9B As shown, the surface of the treated film 96 and the inner side of the recess 95 are covered with water molecules 72. As a result, the adsorption of hydrogen peroxide molecules 71 onto the surface of the treated film 96 is hindered, the etching rate of the treated film 96 decreases, or the etching of the treated film 96 stops.

[0102] Therefore, in the substrate processing apparatus 1, by switching the positive and negative values ​​of the voltage applied to the first electrode 61 at predetermined times, a negative voltage is applied to the first electrode 61, and so on. Figure 9C As shown, the surfaces of the treated membrane 96 and the microstructure 94 are negatively charged. Consequently, water molecules 72 adsorbed on the surfaces of the treated membrane 96 and the microstructure 94 (e.g., the inner surface of the recess 95) are electrolyzed into hydrogen molecules and hydroxide ions, and removed from the surfaces of the treated membrane 96 and the microstructure 94. As a result, a state is achieved where hydrogen peroxide molecules 71 can be adsorbed onto the surface of the treated membrane 96.

[0103] In the substrate processing apparatus 1, a positive voltage is applied to the first electrode 61 by switching the positive and negative values ​​of the voltage applied to the first electrode 61 at predetermined times, and so on. Figure 9D As shown, the surfaces of the treated film 96 and the microstructure 94 (e.g., the inner surface of the recess 95) are positively charged. Hydrogen peroxide molecules 71 are thus adsorbed onto the surface of the treated film 96, and etching of the treated film 96 is achieved through these hydrogen peroxide molecules 71. As a result, etching of the treated film 96 within the recess 95 is promoted, increasing the etching rate.

[0104] Secondly, refer to Figures 10A to 10DThe second principle will be explained. Figure 10A In the diagram, the first electrode 61 (reference) is shown. Figure 2 A positive voltage is applied. By applying a positive voltage to the first electrode 61, the sidewall surfaces 942 (i.e., the inner surfaces of the recess 95) of the two microstructures 94 located on both sides of the recess 95 become positively charged. In other words, the potential of the sidewall surfaces 942 of the microstructures 94 becomes higher than the potential of the processing liquid. Therefore, the etchant, i.e., the negative ions 73, present around the recess 95, easily enters the recess 95. As a result, the contact between the surface of the treated film 96 and the negative ions 73, which act as the etchant, increases, and the etching of the treated film 96 is promoted.

[0105] As the etching of the treated film 96 progresses, such as Figure 10B As shown, the negatively charged product 74 generated by etching increases and remains within the recess 95, making it difficult for the negative ions 73, acting as the etchant, to penetrate the recess 95. Consequently, the contact between the negative ions 73 and the treated film 96 decreases, the etching rate of the treated film 96 decreases, or the etching of the treated film 96 stops. Furthermore, in Figure 10B In order to make the diagram easier to understand, product 74 is marked with parallel diagonal lines ( Figure 10C The same applies to China.

[0106] Therefore, the positive and negative values ​​of the voltage applied to the first electrode 61 are switched at a predetermined time to apply a negative voltage to the first electrode 61. Thus, as... Figure 10C As shown, the sidewall surfaces 942 of the two microstructures 94 located on both sides of the recess 95 (i.e., the inner surfaces of the recess 95) are negatively charged. In other words, the potential of the sidewall surfaces 942 of the microstructures 94 becomes lower than the potential of the processing liquid. As a result, positive ions 75 present around the recess 95 enter the recess 95, and the products 74 retained in the recess 95 are discharged to the outside of the recess 95.

[0107] Then, the polarity of the voltage applied to the first electrode 61 is switched at a predetermined time to apply a positive voltage to the first electrode 61. Thus, as... Figure 10D As shown, the sidewall surface 942 of the microstructure 94 (i.e., the inner surface of the recess 95) is positively charged. As a result, the etchant present around the recess 95, i.e., negative ions 73, enters the recess 95, contacts the film 96 being treated, and promotes the etching of the film 96 being treated, thereby increasing the etching rate.

[0108] Next, the third principle will be explained. During the etching of the film 96 being processed, positive and negative voltages are alternately applied to the first electrode 61. It was then confirmed that when one voltage (positive or negative) is applied, bubbles are generated within the recess 95, while when the other voltage is applied, no bubbles are generated. Therefore, if only this single voltage is continuously applied to the first electrode 61, bubbles will increase and become trapped within the recess 95, reducing the etching rate of the film 96, or even stopping the etching process. Therefore, by switching the positive and negative voltages applied to the first electrode 61 at predetermined times, these bubbles are expelled from the recess 95. This suppresses the bubbles from hindering etching, thereby increasing the etching rate.

[0109] Next, the fourth principle will be explained. The following explanation assumes that the film being treated 96 is a TiN film, and the etching solution is a liquid formed by adding hydrochloric acid to an aqueous hydrogen peroxide solution as an electrolyte. If a positive voltage is applied to the first electrode 61, then the ligands in the etching solution, namely chloride ions (Cl... - The ligands easily enter the recess 95. This promotes the etching of the treated film 96, increasing the etching rate. As etching progresses, the complex (Ti-Cl) generated by etching increases and remains within the recess 95, making it difficult for ligands to enter the recess 95. As a result, the etching rate of the treated film 96 decreases, or the etching of the treated film 96 stops.

[0110] Therefore, by switching the voltage applied to the first electrode 61 from positive to negative at predetermined times, a negative voltage is applied to the first electrode 61, thereby discharging the complex out of the recess 95. Then, by applying a positive voltage to the first electrode 61, as described above, the ligands in the processing solution are made to easily enter the recess 95. This promotes the etching of the treated film 96, increasing the etching rate.

[0111] Furthermore, it is not clearly stated which of the first to fourth principles is dominant. Additionally, the increase in etching rate may be due to a combination of these principles with other principles, or it may be due to principles other than these. In either case, in step S14, the applied voltage is repeatedly switched at a voltage switching cycle of 0.05 seconds or more, causing the potential of the sidewall surface 942 of the microstructure 94 to repeatedly switch between the first potential and the second potential, thereby promoting the etching of the film 96 to be processed within the recess 95.

[0112] In the substrate processing apparatus 1, after a predetermined processing time has elapsed since step S14, the etching of the substrate 9 is stopped by several actions: stopping the supply of processing liquid to the substrate 9, oscillating the nozzle 51, switching the rotation speed of the substrate 9, and applying voltage through the power supply unit 63. After etching is completed, rinsing liquid is supplied from the nozzle 51 to the center of the upper surface 91 of the substrate 9, and the rotation speed of the substrate 9 is increased.

[0113] The rinsing liquid supplied to the substrate 9 diffuses across the entire upper surface 91 of the substrate 9 using the centrifugal force generated by the rotation of the substrate 9. This performs a rinsing process, i.e., washing away the processing liquid and the like adhering to the substrate 9 (step S15). The rotational speed of the substrate 9 in step S15 is, for example, 800 rpm or more. The rinsing liquid on the substrate 9 is dispersed radially outward from the periphery of the substrate 9 using the centrifugal force generated by the rotation of the substrate 9 and is received by the cup portion 4. Furthermore, the vertical position of the nozzle 51 when supplying the rinsing liquid can be the same as or different from the vertical position of the nozzle 51 in step S12.

[0114] After rinsing the substrate 9 for a predetermined time, the supply of rinsing solution is stopped. Then, the rotational speed of the substrate 9 is further increased. The rinsing solution on the substrate 9 is then removed, thereby performing a drying process on the substrate 9 (step S16). The rotational speed of the substrate 9 in step S16 is, for example, 1000 rpm or more. Furthermore, the drying process can be performed using various known methods. After the drying process of the substrate 9 is completed, the rotation of the substrate 9 is stopped, and the substrate 9 is removed from the substrate processing apparatus 1.

[0115] Next, referring to Tables 1 to 7, Examples 1 to 28 and Comparative Examples 1 to 3 of etching the treated film 96 in the recess 95 will be described.

[0116] [Table 1]

[0117]

[0118] [Table 2]

[0119]

[0120] [Table 3]

[0121]

[0122] [Table 4]

[0123]

[0124] [Table 5]

[0125]

[0126] [Table 6]

[0127]

[0128] [Table 7]

[0129]

[0130] In Examples 1-28 and Comparative Example 2, the etching of the film 96 to be processed in the substrate processing apparatus 1 was simulated, and the etching was performed using… Figure 11 The experimental apparatus 97 shown was used to treat the test piece 98 in steps S11 to S16. In Comparative Examples 1 and 3, the voltage application in step S14 was omitted. Furthermore, these treatments performed on the test piece 98 were carried out in an atmospheric environment at room temperature (e.g., 25°C).

[0131] The experimental apparatus 97 includes an electrolytic cell 971, a test electrode 972, a counter electrode 973, a reference electrode 974, and a power supply unit 975. An "VM-3" manufactured by EC FRONTIER Inc. is used as the electrolytic cell 971. The test piece 98 is placed on the base 976 of the electrolytic cell 971, and the tank cover 977 on the base 976 is filled with a processing solution for etching. The upper surface of the test piece 98 is in contact with the processing solution inside the tank cover 977. The contact area between the test piece 98 and the processing solution is defined as 1 cm² by an O-ring. 2 On the upper surface of the test piece 98, a plurality of recesses 95 are formed (see reference). Figure 4 ) multiple microstructures 94.

[0132] Use alligator clips as a reference to the first electrode 61 (see). Figure 2 The corresponding test electrode 972 is used. The test electrode 972 is electrically connected to the test piece 98 by clamping the end of the test piece 98 with the alligator clip. The "CE-100" manufactured by EC FRONTIER Inc. is used as the relative electrode 973. The "RE-T16" manufactured by EC FRONTIER Inc. is used as the reference electrode 974. The "RE-T16" is a silver-silver chloride electrode (Ag / AgCl electrode) using a 3.0 mol / L potassium chloride (KCl) aqueous solution as the internal solution, and its potential relative to the NHE (standard hydrogen electrode) is +0.208 V at 25°C. The relative electrode 973 and the reference electrode 974 are inserted into the tank cover 977 from the top, and come into contact with the processing solution inside the tank cover 977. A potentiostat "VSP-300-SC" manufactured by Bio-Logic Science Inc. is used as the power supply unit 975.

[0133] In Examples 1-17 and Comparative Examples 1-2 shown in Tables 1-4, the processing solution used for etching was SC2, and the etching time (i.e., the processing time of step S14) was 60 minutes. This processing solution was a mixture of approximately 20 mol% hydrogen peroxide water, approximately 22 mol% hydrochloric acid aqueous solution, and DIW mixed in a volume ratio of 1:1:8.

[0134] In Examples 18-28 and Comparative Example 3 shown in Tables 5-7, the etching solution used was hydrogen peroxide water, and the etching time (i.e., the processing time of step S14) was 120 minutes. This etching solution was a mixture of approximately 20 mol% hydrogen peroxide water and DIW at a volume ratio of 1:8. No other chemical solutions such as hydrochloric acid were added to this etching solution. That is, the concentration of hydrochloric acid in the etching solution was 0 mol% and 0% by mass.

[0135] The etching amounts in Tables 1 through 7 are... Figure 12 The surface 961 of the film 96 being processed, indicated by a double-dotted line, is in the state before etching begins. Figure 12 The depth direction of the recess 95 between the surfaces 962 of the treated film 96 after etching at the specified time (represented by solid lines) is shown in the image. Figure 12 The distance D1 in the left and right directions (within the range). Furthermore, as... Figure 12 As shown, distance D1 is the distance between the surface 961 of the film being processed 96 and the lowest point of the surface 962 of the film being processed 96 within the recess 95 (i.e., the position furthest from surface 961 in the depth direction). This etching amount is the arithmetic mean of the distances D1 of the six recesses 95. This distance D1 is obtained by observing a cross-sectional SEM image of the substrate 9.

[0136] As described above, SC2 was used as the processing solution in Examples 1-17 and Comparative Examples 1-2 shown in Tables 1-4. In Examples 1-5 shown in Table 1, the first and second applied voltages in step S14 were changed, and the etching amount of the treated film 96 was measured. In Example 1, the applied voltage from the power supply unit 975 was a DC voltage, the second voltage was set to -8 V, and the first voltage was set to +8 V. Furthermore, the voltage switching cycle of the applied voltage was 6 seconds. That is, in Example 1, the potential of the sidewall surface 942 of the microstructure 94 (i.e., the inner surface of the recess 95) switched between -8 V (the second potential) and +8 V (the first potential) with a voltage switching cycle of 6 seconds. In Example 1, the etching amount was 24 nm.

[0137] Example 2 is identical to Example 1 except that the second voltage is set to -1 V and the first voltage is set to +1 V. In Example 2, the potential of the sidewall surface 942 of the microstructure 94 switches between -1 V (the second potential) and +1 V (the first potential) with a voltage switching cycle of 6 seconds. In Example 2, the etching depth is 26 nm.

[0138] Example 3 is identical to Example 1 except that the second voltage is set to -0.8 V and the first voltage is set to +0.8 V. In Example 3, the potential of the sidewall surface 942 of the microstructure 94 switches between -0.8 V (the second potential) and +0.8 V (the first potential) at a voltage switching cycle of 6 seconds. In Example 3, the etching depth is 25.5 nm.

[0139] Example 4 is identical to Example 1 except that the second voltage is set to -0.6 V and the first voltage is set to +0.6 V. In Example 4, the potential of the sidewall surface 942 of the microstructure 94 switches between -0.6 V (the second potential) and +0.6 V (the first potential) at a voltage switching cycle of 6 seconds. In Example 4, the etching depth is 25.5 nm.

[0140] Example 5 is identical to Example 1 except that the second voltage is set to -0.5 V and the first voltage is set to +0.5 V. In Example 5, the potential of the sidewall surface 942 of the microstructure 94 switches between -0.5 V (the second potential) and +0.5 V (the first potential) at a voltage switching cycle of 6 seconds. In Example 5, the etching depth is 27.5 nm.

[0141] In Comparative Example 1, as described above, the voltage application in step S14 was omitted. In Comparative Example 1, the etching depth was 11 nm.

[0142] Comparing Examples 1 to 5 with Comparative Example 1, it can be seen that by performing step S14 (switching the applied voltage), the etching rate of the film 96 to be processed in the recess 95 will increase even when the applied voltage is different.

[0143] In Examples 6-10 and Comparative Example 2 shown in Table 2, the first and second applied voltages in step S14 were changed, and the etching amount of the treated film 96 was measured. In Example 6, the applied voltage from the power supply unit 975 was a DC voltage, the second voltage was set to -8 V, and the first voltage was set to 0 V. Furthermore, the voltage switching cycle of the applied voltage was 6 seconds. That is, in Example 6, the potential of the sidewall surface 942 of the microstructure 94 (i.e., the inner surface of the recess 95) switched between -8 V (the second potential) and 0 V (the first potential) with a voltage switching cycle of 6 seconds. In Example 6, the etching amount was 26 nm.

[0144] Example 7 is identical to Example 6 except that the first voltage is set to +1 V. In Example 7, the potential of the sidewall surface 942 of the microstructure 94 switches between -8 V (the second potential) and +1 V (the first potential) at a voltage switching cycle of 6 seconds. In Example 7, the etching depth is 25.5 nm.

[0145] Example 8 is identical to Example 6 except that the power supply unit 975 is turned off at a predetermined time after the first voltage is applied. With the power supply unit 975 turned off, the open-circuit potential of the surface of the test piece 98 is +0.6 V to +0.8 V. In Example 8, the potential of the sidewall surface 942 of the microstructure 94 switches between -8 V (the second potential) and the open-circuit potential (the first potential) at a voltage switching cycle of 6 seconds. In Example 8, the etching depth is 25.5 nm.

[0146] Example 9 is identical to Example 6 except that the first voltage is set to +8 V. In Example 9, the potential of the sidewall surface 942 of the microstructure 94 switches between -8 V (the second potential) and +8 V (the first potential) with a voltage switching cycle of 6 seconds. In Example 9, the etching depth is 27 nm.

[0147] Example 10 is identical to Example 7 except that the second potential is set to -1 V. In Example 10, the potential of the sidewall surface 942 of the microstructure 94 switches between -1 V (the second potential) and +1 V (the first potential) at a voltage switching cycle of 6 seconds. In Example 10, the etching depth is 25.5 nm.

[0148] Furthermore, in Examples 9 and 10, the experimental conditions were the same as in Examples 1 and 2 of Table 1, but the experimental dates and other factors were different. Therefore, the etching amount was slightly different compared to Examples 1 and 2. Similarly, in other examples, when the experimental conditions were the same but the etching amount was different, the difference in experimental dates and other factors was the reason.

[0149] Comparative Example 2 is identical to Example 6 except that the first voltage is set to -2 V. In Comparative Example 2, the potential of the sidewall surface 942 of the microstructure 94 switches between -8 V and -2 V with a voltage switching cycle of 6 seconds. In Comparative Example 2, the etching depth is 11 nm, which is substantially the same as in Comparative Example 1 (refer to Table 1).

[0150] Comparing Examples 6-10 with Comparative Example 2, it can be seen that when performing step S14 (switching the applied voltage), if both the first potential and the second potential of the sidewall surface 942 are negative (i.e., have the same sign) (Comparative Example 2), the etching rate of the film 96 to be processed in the recess 95 will not increase. On the other hand, if the first potential and the second potential of the sidewall surface 942 do not have the same sign, the etching rate of the film 96 to be processed in the recess 95 will increase in roughly the same way as in the case where the absolute values ​​of the first potential and the second potential are different (Examples 6-8) and in the case where the absolute values ​​of the first potential and the second potential are the same (Examples 9-10).

[0151] Furthermore, Comparative Example 2 is ultimately only a comparative example of etching the film 96 to be processed within the recess 95. Regarding the end face 941 of the microstructure 94 (see reference...) Figure 4 It was confirmed that by applying voltage as described above, the etching rate increased compared to Comparative Example 1 where no voltage was applied, on the treated film 96 (i.e., the treated film 96 outside the recess 95).

[0152] In Examples 11-14 shown in Table 3, the voltage switching cycle of the applied voltage in step S14 was changed, and the etching amount of the treated film 96 was measured. In Example 11, the applied voltage from the power supply unit 975 was a DC voltage, the second voltage was set to -1 V, and the first voltage was set to +1 V. Furthermore, the voltage switching cycle of the applied voltage was 2 seconds. That is, in Example 11, the potential of the sidewall surface 942 of the microstructure 94 (i.e., the inner surface of the recess 95) switched between -1 V (the second potential) and +1 V (the first potential) with a voltage switching cycle of 2 seconds. In Example 11, the etching amount was 20.5 nm.

[0153] Example 12 is identical to Example 11 except that the voltage switching period is set to 6 seconds. In Example 12, the potential of the sidewall surface 942 of the microstructure 94 switches between -1 V (the second potential) and +1 V (the first potential) with a voltage switching period of 6 seconds. In Example 12, the etching depth is 21.5 nm.

[0154] Example 13 is identical to Example 11 except that the voltage switching period is set to 12 seconds. In Example 13, the potential of the sidewall surface 942 of the microstructure 94 switches between -1 V (the second potential) and +1 V (the first potential) with a voltage switching period of 12 seconds. In Example 13, the etching depth is 22 nm.

[0155] Example 14 is identical to Example 11 except that the voltage switching period is set to 18 seconds. In Example 14, the potential of the sidewall surface 942 of the microstructure 94 switches between -1 V (the second potential) and +1 V (the first potential) with an 18-second voltage switching period. In Example 14, the etching depth is 19.5 nm.

[0156] In Comparative Example 1, as described above, the voltage application in step S14 was omitted. In Comparative Example 1, as described above, the etching amount was 11 nm.

[0157] Comparing Examples 11-14 with Comparative Example 1, it can be seen that by performing step S14 (switching the applied voltage), the etching rate of the film 96 processed in the recess 95 will increase even when the voltage switching cycle is different.

[0158] In Examples 15-17 shown in Table 4, the applied voltage in step S14 was set to an AC voltage, and the frequency of this AC voltage was changed (i.e., the voltage switching cycle was changed), and the etching amount of the treated film 96 was measured. In Example 15, the applied voltage from the power supply unit 975 was an AC voltage, the second voltage was set to -1 V, and the first voltage was set to +1 V. Furthermore, the frequency of the applied voltage was 0.5 Hz (i.e., the voltage switching cycle: 2 seconds). That is, in Example 15, the potential of the sidewall surface 942 of the microstructure 94 (i.e., the inner surface of the recess 95) switched between -1 V (the second potential) and +1 V (the first potential) with a voltage switching cycle of 2 seconds. In Example 15, the etching amount was 21 nm.

[0159] Example 16 is identical to Example 15 except that the frequency is set to 1 Hz (voltage switching cycle: 1 second). In Example 16, the potential of the sidewall surface 942 of the microstructure 94 switches between -1 V (the second potential) and +1 V (the first potential) with a voltage switching cycle of 1 second. In Example 16, the etching depth is 22 nm.

[0160] Example 17 is identical to Example 15 except that the frequency is set to 5 Hz (voltage switching cycle: 0.2 seconds). In Example 17, the potential of the sidewall surface 942 of the microstructure 94 switches between -1 V (the second potential) and +1 V (the first potential) with a voltage switching cycle of 0.2 seconds. In Example 17, the etching depth is 16.5 nm.

[0161] In Comparative Example 1, as described above, the voltage application in step S14 was omitted. In Comparative Example 1, as described above, the etching amount was 11 nm.

[0162] Comparing Examples 15-17 with Comparative Example 1, it can be seen that by performing step S14 (switching the applied voltage), the etching rate of the film 96 processed in the recess 95 increases even when the frequency of the AC voltage is different (i.e., the voltage switching cycle is different). Furthermore, comparing Examples 15 with Example 11 (Table 3), it can be seen that when the first voltage, the second voltage, and the voltage switching cycle are the same, the etching rate is substantially the same regardless of whether the applied voltage is DC or AC.

[0163] As described above, in Examples 18-28 and Comparative Example 3 shown in Tables 5-7, hydrogen peroxide water was used as the treatment solution. In Examples 18-22 shown in Table 5, the first and second applied voltages in step S14 were changed, and the etching amount of the treated film 96 was measured. In Example 18, the applied voltage from the power supply unit 975 was a DC voltage, the second voltage was set to -1 V, and the first voltage was set to +1 V. Furthermore, the voltage switching cycle of the applied voltage was 2 seconds. That is, in Example 18, the potential of the sidewall surface 942 of the microstructure 94 (i.e., the inner surface of the recess 95) switched between -1 V (the second potential) and +1 V (the first potential) with a voltage switching cycle of 2 seconds. In Example 18, the etching amount was 18 nm.

[0164] Example 19 is identical to Example 18 except that the second voltage is set to -2 V and the first voltage is set to +2 V. In Example 19, the potential of the sidewall surface 942 of the microstructure 94 switches between -2 V (the second potential) and +2 V (the first potential) at a voltage switching cycle of 2 seconds. In Example 19, the etching depth is 18.5 nm.

[0165] Example 20 is identical to Example 18 except that the second voltage is set to -3 V and the first voltage is set to +3 V. In Example 20, the potential of the sidewall surface 942 of the microstructure 94 switches between -3 V (the second potential) and +3 V (the first potential) at a voltage switching cycle of 2 seconds. In Example 20, the etching depth is 19 nm.

[0166] Example 21 is identical to Example 18 except that the second voltage is set to -5 V and the first voltage is set to +5 V. In Example 21, the potential of the sidewall surface 942 of the microstructure 94 switches between -5 V (the second potential) and +5 V (the first potential) at a voltage switching cycle of 2 seconds. In Example 21, the etching depth is 22.5 nm.

[0167] Example 22 is identical to Example 18 except that the second voltage is set to -8 V and the first voltage is set to +8 V. In Example 22, the potential of the sidewall surface 942 of the microstructure 94 switches between -8 V (the second potential) and +8 V (the first potential) at a voltage switching cycle of 2 seconds. In Example 22, the etching depth is 24.5 nm.

[0168] In Comparative Example 3, as described above, the voltage application in step S14 was omitted. In Comparative Example 3, the etching depth was 15.5 nm.

[0169] Comparing Examples 18-22 with Comparative Example 3, it can be seen that by performing step S14 (switching the applied voltage), the etching rate of the film 96 in the recess 95 will increase even when the applied voltage is different.

[0170] In Examples 23-25 ​​shown in Table 6, the voltage switching cycle of the applied voltage in step S14 was changed, and the etching amount of the treated film 96 was measured. In Example 23, the applied voltage from the power supply unit 975 was a DC voltage, the second voltage was set to -5 V, and the first voltage was set to +5 V. Furthermore, the voltage switching cycle of the applied voltage was 0.5 seconds. That is, in Example 23, the potential of the sidewall surface 942 of the microstructure 94 (i.e., the inner surface of the recess 95) switched between -5 V (the second potential) and +5 V (the first potential) with a voltage switching cycle of 0.5 seconds. In Example 23, the etching amount was 19 nm.

[0171] Example 24 is identical to Example 23 except that the voltage switching period is set to 1 second. In Example 24, the potential of the sidewall surface 942 of the microstructure 94 switches between -5 V (the second potential) and +5 V (the first potential) with a voltage switching period of 1 second. In Example 24, the etching depth is 21 nm.

[0172] Example 25 is identical to Example 23 except that the voltage switching period is set to 2 seconds. In Example 25, the potential of the sidewall surface 942 of the microstructure 94 switches between -5 V (the second potential) and +5 V (the first potential) with a voltage switching period of 2 seconds. In Example 25, the etching depth is 20 nm.

[0173] In Comparative Example 3, as described above, the voltage application in step S14 was omitted. In Comparative Example 3, as described above, the etching depth was 15.5 nm.

[0174] Comparing Examples 23-25 ​​with Comparative Example 3, it can be seen that by performing step S14 (switching the applied voltage), the etching rate of the film 96 to be processed in the recess 95 will increase even when the voltage switching cycle is different.

[0175] In Examples 26-28 shown in Table 7, the applied voltage in step S14 was set to an AC voltage, and the frequency of this AC voltage was changed (i.e., the voltage switching cycle was changed), and the etching amount of the treated film 96 was measured. In Example 26, the applied voltage from the power supply unit 975 was an AC voltage, the second voltage was set to -5 V, and the first voltage was set to +5 V. Furthermore, the frequency of the applied voltage was 1 Hz (i.e., the voltage switching cycle: 1 second). That is, in Example 26, the potential of the sidewall surface 942 of the microstructure 94 (i.e., the inner surface of the recess 95) switched between -5 V (the second potential) and +5 V (the first potential) with a voltage switching cycle of 1 second. In Example 26, the etching amount was 20.5 nm.

[0176] Example 27 is identical to Example 26 except that the frequency is set to 10 Hz (voltage switching cycle: 0.1 seconds). In Example 27, the potential of the sidewall surface 942 of the microstructure 94 switches between -5 V (the second potential) and +5 V (the first potential) with a voltage switching cycle of 0.1 seconds. In Example 27, the etching depth is 26 nm.

[0177] Example 28 is identical to Example 26 except that the frequency is set to 20 Hz (voltage switching period: 0.05 seconds). In Example 28, the potential of the sidewall surface 942 of the microstructure 94 switches between -5 V (the second potential) and +5 V (the first potential) with a voltage switching period of 0.05 seconds. In Example 28, the etching depth is 17.5 nm.

[0178] In Comparative Example 3, as described above, the voltage application in step S14 was omitted. In Comparative Example 3, as described above, the etching depth was 15.5 nm.

[0179] Comparing Examples 26-28 with Comparative Example 3, it can be seen that by performing step S14 (switching the applied voltage), the etching rate of the film 96 processed in the recess 95 increases even when the frequency of the AC voltage is different (i.e., the voltage switching cycle is different). Furthermore, comparing Examples 26 and 24 (Table 6), it can be seen that when the first voltage, the second voltage, and the voltage switching cycle are the same, the etching rate is substantially the same regardless of whether the applied voltage is DC or AC.

[0180] As described above, the substrate processing apparatus 1 includes a substrate holding section 21, a substrate rotation mechanism 23, a nozzle 51, a nozzle moving mechanism 55, a first electrode 61, a second electrode 62, a power supply section 63, and a control section 8. The substrate holding section 21 holds a substrate 9 with a film 96 to be processed on its upper surface 91 in a horizontal position. The substrate rotation mechanism 23 rotates the substrate holding section 21 about a central axis J1 pointing vertically. The nozzle 51 supplies etching solution to the upper surface 91 of the substrate 9 from above, bringing it into contact with the film 96 to be processed. The nozzle moving mechanism 55 causes the nozzle 51 to swing horizontally between the center and periphery of the rotating substrate 9.

[0181] The first electrode 61 is electrically connected to the substrate 9. The second electrode 62 is electrically connected to the processing liquid ejected from the nozzle 51. The power supply unit 63 applies a voltage between the first electrode 61 and the second electrode 62. The control unit 8 controls the substrate rotation mechanism 23, the nozzle 51, and the power supply unit 63. Under the control of the control unit 8, while continuously supplying processing liquid from the nozzle 51 to the upper surface 91 of the substrate 9 and applying a voltage between the first electrode 61 and the second electrode 62, the rotational speed of the substrate 9 repeatedly switches between different first and second rotational speeds at a predetermined rotational speed switching cycle, wherein the nozzle 51 oscillates above the rotating substrate 9.

[0182] In the substrate processing apparatus 1, as described above, by switching the rotational speed of the substrate 9, the processing liquid can flow within the recess 95 on the substrate 9, thereby increasing the etching rate of the film 96 to be processed within the recess 95. Furthermore, in this state, by applying a voltage between the substrate 9 and the processing liquid, the etching rate of the film 96 to be processed can be further increased.

[0183] As described above, the rotation speed switching period is preferably an integer multiple of the voltage switching period. Therefore, a predetermined number of voltage switching operations are performed during the period when the rotation speed of the substrate 9 accelerates and decelerates once each. As a result, the etching rate of the film 96 being processed can be optimally increased.

[0184] More preferably, the rotation speed switching period is an even multiple of the voltage switching period. Therefore, during the period from the start of acceleration of the substrate 9's rotation speed to the start of deceleration, the switching of the applied voltage from the first voltage to the second voltage and from the second voltage to the first voltage is performed at least once. Furthermore, during the period from the start of deceleration of the substrate 9's rotation speed to the start of acceleration, the switching of the applied voltage from the first voltage to the second voltage and from the second voltage to the first voltage is also performed at least once. As a result, the etching rate of the processed film 96 can be further increased.

[0185] As described above, the switching of the rotational speed of the substrate 9 and the switching of the applied voltage are performed simultaneously under the control of the control unit 8. As a result, the etching rate of the film 96 being processed can be increased more effectively.

[0186] As described above, in the substrate processing apparatus 1, under the control of the control unit 8, a voltage is applied and repeatedly switched between a first voltage and a second voltage at a predetermined voltage switching cycle, in parallel with the switching of the rotational speed of the substrate 9. As a result, the potential of the sidewall surface 942 of the recess 95 forming the pattern 93 on the substrate 9 repeatedly switches between a first potential and a second potential less than the first potential. The first potential is 0 V or higher, and the second potential is 0 V or lower. Therefore, as illustrated in Examples 1 to 28, the etching rate of the film 96 being processed within the recess 95 can be increased. The reason for this increased etching rate can be considered, for example, as described below.

[0187] In the first principle, by repeatedly switching the potential of the sidewall surface 942, water molecules and other substances adsorbed on the surface of the film 96 to be treated within the recess 95 can be better electrolyzed, and etchants such as hydrogen peroxide can be better adsorbed onto the film 96 to be treated. As a result, the etching rate of the film 96 to be treated can be increased.

[0188] Furthermore, in the second principle, by repeatedly switching the potential of the sidewall surface 942, the etched products (hereinafter also referred to as "etched products") that increase within the recess 95 can be better discharged out of the recess 95. As a result, the etchant becomes easier to enter the recess 95, thus increasing the etching rate of the treated film 96.

[0189] In the third principle, by repeatedly switching the potential of the sidewall surface 942, bubbles generated inside the recess 95 can be better discharged to the outside of the recess 95. As a result, the etchant becomes easier to enter the recess 95, thus increasing the etching rate of the treated film 96.

[0190] In the fourth principle, by repeatedly switching the potential of the sidewall surface 942, the complexes generated by etching that increase within the recess 95 can be better discharged out of the recess 95. As a result, the etchant becomes easier to enter the recess 95, thus increasing the etching rate of the treated film 96.

[0191] As described above, the voltage switching cycle for applying the voltage is preferably 0.05 seconds or more. This allows for a further increase in the etching rate of the film 96 being processed within the recess 95. The reasons for this further increase in etching rate can be considered, for example, as described below.

[0192] In the first principle, when the voltage switching cycle is less than 0.05 seconds, the applied voltage is switched before sufficient electrolysis of water molecules and the like adsorbed on the surface of the film 96 being treated, which may result in insufficient electrolysis of the water molecules and the like. Therefore, the adsorption of the etchant onto the film 96 being treated is hindered by water molecules and the like, and the increase in the etching rate may not be sufficient. On the other hand, when the voltage switching cycle is 0.05 seconds or more, the electrolysis of water molecules and the like will proceed better, and the etching rate of the film 96 being treated will further increase.

[0193] In the second principle, when the voltage switching cycle is less than 0.05 seconds, the applied voltage is switched before the etched product is fully discharged from the recess 95, resulting in insufficient discharge of the etched product from the recess 95. Therefore, the entry of the etchant into the recess 95 is hindered, and the increase in the etching rate may be insufficient. On the other hand, when the voltage switching cycle is 0.05 seconds or more, the discharge of the etched product from the recess 95 is better, and the etching rate of the treated film 96 is further increased.

[0194] In the third principle, when the voltage switching cycle is less than 0.05 seconds, the applied voltage is switched before the bubbles are fully expelled from the recess 95, which may result in insufficient expulsion of the bubbles from the recess 95. Therefore, the entry of the etchant into the recess 95 is hindered, and the increase in the etching rate may be insufficient. On the other hand, when the voltage switching cycle is 0.05 seconds or more, the expulsion of the bubbles from the recess 95 is more efficient, and the etching rate of the treated film 96 is further increased.

[0195] In the fourth principle, when the voltage switching cycle is less than 0.05 seconds, the applied voltage switches before the complex is fully discharged from the recess 95, which may result in insufficient discharge of the complex from the recess 95. Therefore, the entry of the etchant into the recess 95 is hindered, and the increase in the etching rate may be insufficient. On the other hand, when the voltage switching cycle is 0.05 seconds or more, the discharge of the complex from the recess 95 will proceed better, and the etching rate of the treated film 96 will further increase.

[0196] As described above, when the applied voltage is a DC voltage, the voltage switching cycle is preferably 0.5 seconds or more. This allows for a better increase in the etching rate of the film 96 being processed.

[0197] As described above, when the applied voltage is an alternating current voltage, the voltage switching cycle is preferably 0.2 seconds or more. This allows for a better increase in the etching rate of the film 96 being processed.

[0198] The substrate processing method includes the following steps: holding a substrate 9 with a film 96 to be processed on its upper surface 91 in a horizontal state (step S11); continuously supplying a processing liquid for etching from a nozzle 51 to the upper surface 91 of the substrate 9, wherein the nozzle 51 is above the substrate 9 which is rotating about a central axis J1 in the vertical direction, and swings horizontally between the center and the periphery of the substrate 9 (step S12); in parallel with step S12, repeatedly switching the rotational speed of the substrate 9 between a first rotational speed and a second rotational speed that are different from each other at a predetermined rotational speed switching cycle (step S13); and in parallel with step S13, applying a voltage between the substrate 9 and the processing liquid ejected from the nozzle 51, and repeatedly switching the applied voltage between a first voltage and a second voltage that are different from each other at a predetermined voltage switching cycle, thereby causing the potential of the sidewall surface 942 of the recess 95 forming the pattern 93 (i.e., the micro-pattern 93) on the substrate 9 to repeatedly switch between a first potential and a second potential that is less than the first potential (step S14). The first potential is above 0 V, and the second potential is below 0 V. Therefore, as described above, the etching rate of the film 96 to be processed located within the recess 95 can be increased.

[0199] The configuration of the substrate processing apparatus 1 is not limited to the example described, and various modifications can be made. For example, in Figure 13 In the illustrated substrate processing apparatus 1a, the plurality of first electrodes 61 (refer to) that are disposed on the plurality of clamping pins 212 are replaced. Figure 2 A first electrode 61a is disposed on the upper surface of the base portion 211 of the substrate holding portion 21. The first electrode 61a is a conductive component that is approximately annular or approximately circular in shape and centered on the central axis J1. The first electrode 61a is formed, for example, of platinum (Pt) or glassy carbon (GC), in a substantially similar manner to the first electrode 61. In plan view, the outer diameter of the first electrode 61a is, for example, slightly smaller than the diameter of the substrate 9. Furthermore, in a plane, the outer diameter of the first electrode 61a may be larger than or approximately equal to the diameter of the substrate 9. The first electrode 61a, like the plurality of first electrodes 61, is electrically connected to the power supply portion 63 via the first transmission portion 64 and the second transmission portion 65. Furthermore, the shape and material of the first electrode 61a can be varied in various ways.

[0200] The upper surface 611 of the first electrode 61a protrudes from the upper surface of the base portion 211 and is not covered by the base portion 211. The upper surface 611 of the first electrode 61a spans approximately the entire lower surface 92 of the substrate 9 and is in direct surface contact with the lower surface 92 in the vertical direction. Thus, the first electrode 61a is electrically connected to the substrate 9. In the substrate processing apparatus 1a, regardless of the position of the oscillating nozzle 51, the upper surface 611 of the first electrode 61a is always facing the nozzle 51, on which the second electrode 62 is provided, across the substrate 9 in the vertical direction.

[0201] In the substrate processing apparatus 1a, a first electrode 61a is provided that makes surface contact with the lower surface 92 of the substrate 9 over a relatively large area. Therefore, compared to the substrate processing apparatus 1 where the first electrode 61a is electrically connected to the substrate 9 only at its periphery, current concentration at the periphery of the substrate 9 is alleviated during etching in step S14. This allows for suppression of the current concentration at the treated film 96 (see reference 1a). Figure 4 Because of its radial position on the substrate 9, a potential difference arises. Furthermore, the first electrode 61a spans the entire circumferential direction centered on the central axis J1 and is in direct contact with the substrate 9. Therefore, it is also possible to suppress potential differences in the processed film 96 due to its circumferential position on the substrate 9 (e.g., in the substrate processing apparatus 1, the angle between the circumferential direction and the clamping pin 212). As a result, the uniformity of the etching rate on the substrate 9 is improved in both the radial and circumferential directions.

[0202] In the substrate processing apparatus 1a, the first electrode 61a can also move vertically relative to the base portion 211. In this case, when the substrate 9 is placed into the substrate processing apparatus 1a and held by the substrate holding portion 21, the first electrode 61a can be separated from the substrate 9 downwards. After the substrate 9 is held by multiple clamping pins 212, the first electrode 61a can be raised vertically relative to the base portion 211 and come into direct contact with the lower surface 92 of the substrate 9. The mechanism for moving the first electrode 61a vertically relative to the base portion 211 can be, for example, an electric linear motor, a cylinder, or a ball screw and an electric rotary motor connected to the first electrode 61a.

[0203] As explained above, the substrate processing apparatus 1a includes a first electrode 61a disposed on the upper surface of the base portion 211 and in contact with the lower surface 92 of the substrate 9. This improves the uniformity of the etching rate on the substrate 9.

[0204] Furthermore, in the substrate processing apparatus 1a, in addition to the first electrode 61a, a plurality of first electrodes 61 respectively disposed on the upper inner surface 213 of a plurality of clamping pins 212 may also be provided (see reference). Figure 2In this case, the plurality of first electrodes 61, like the first electrode 61a, are electrically connected to the power supply unit 63 via the first transmission unit 64 and the second transmission unit 65. During the etching in step S14, by applying a voltage from the power supply unit 63, the first electrode 61a and the plurality of first electrodes 61 are brought to the same potential.

[0205] like Figure 13 As illustrated, in the substrate processing apparatus 1a, a heating section 25 for heating the substrate 9 from below may also be provided. The heating section 25 includes a heating plate 251 disposed inside the base portion 211 of the substrate holding portion 21. The heating plate 251 is disposed below the first electrode 61a disposed on the upper surface of the base portion 211. In other words, the first electrode 61a is disposed between the heating plate 251 built into the base portion 211 and the lower surface 92 of the substrate 9.

[0206] The heating plate 251 is a generally annular or generally circular plate-shaped component centered on the central axis J1. The outer diameter of the heating plate 251 is, for example, slightly smaller than the diameter of the substrate 9. The heating plate 251 is an electric heater formed by embedding electric heating wires (not shown) inside the heating plate body. By supplying electricity to these electric heating wires, the heating plate body, made of ceramic or the like, is heated.

[0207] In the substrate processing apparatus 1a, during etching in step S14, a heating plate 251 disposed below the first electrode 61a indirectly contacts the lower surface 92 of the substrate 9 via the first electrode 61a. The substrate 9 is heated from below via the first electrode 61a through the heating plate 251. The first electrode 61a is preferably formed of a material with relatively high thermal conductivity, such as glassy carbon.

[0208] In the substrate processing apparatus 1a, the substrate 9 is heated by the heating unit 25, thereby heating the film 96 to be processed (see reference). Figure 4 As the temperature increases, the etching rate of the film 96 being processed increases. Furthermore, the resistance of the substrate 9 decreases with increasing temperature; therefore, by heating the substrate 9, the applied voltage required to promote etching can be reduced. Additionally, during etching in step S14, the temperature of the upper surface 91 of the substrate 9 is preferably set to, for example, 40°C to 100°C.

[0209] In the substrate processing apparatus 1a, the heating unit 25 can also be controlled by the operation control unit 82 in such a way that the temperature of the heating plate 251 varies according to its radial position. In other words, by controlling the heating unit 25 through the operation control unit 82, the amount of heat per unit area supplied from the heating plate 251 to the lower surface 92 of the substrate 9 varies according to the radial distance on the substrate 9 from the central axis J1.

[0210] Specifically, for example, within the heating plate body of the heating plate 251, a plurality of heating wires are arranged in a substantially concentric circle around the central axis J1. The power supplied to these heating wires can be controlled independently. In the heating plate 251, the temperature of the heating plate 251 is adjusted at each radial position by individually adjusting the power supplied to these heating wires. Thus, the heat per unit area imparted from the heating plate 251 to the lower surface 92 of the substrate 9 is adjusted at each radial position.

[0211] In the substrate processing apparatus 1a, for example, if the etching rate at the periphery of the substrate 9 becomes lower than the etching rate at the center of the substrate 9 after uniform heating, the heating section 25 is controlled to make the temperature at the periphery of the heating plate 251 higher than the temperature at the center of the heating plate 251. This improves the radial uniformity of the etching rate of the substrate 9.

[0212] As explained above, the substrate processing apparatus 1a also includes a heating section 25 that heats the substrate 9 from below. This allows the temperature of the substrate 9 to rise, thereby increasing the etching rate of the film 96 being processed.

[0213] As described above, the heating element 25 is preferably capable of varying the amount of heat applied to the lower surface 92 of the substrate 9 per unit area based on its distance from the center (i.e., the central axis J1) of the substrate 9. This improves the radial uniformity of the etching rate of the substrate 9.

[0214] Various modifications can be made to the substrate processing apparatuses 1 and 1a.

[0215] For example, in steps S13 and S14, the switching of the rotational speed of the substrate 9 (i.e., the start of acceleration or deceleration of the rotational speed of the substrate 9) does not necessarily have to be performed simultaneously with the switching of the applied voltage, and can also be performed at a different time than the switching of the applied voltage.

[0216] The rotational speed switching period of substrate 9 does not necessarily have to be an even multiple of the voltage switching period of the applied voltage; it can also be an odd multiple. Alternatively, the rotational speed switching period may not be an integer multiple of the voltage switching period. Furthermore, as mentioned above, the rotational speed switching period can also be shorter than the voltage switching period.

[0217] In the substrate processing apparatus 1, similarly to the substrate processing apparatus 1a, a heating plate 251 can also be provided within the base portion 211 of the substrate holding portion 21. In the substrate processing apparatus 1, as described above, the first electrode 61 is provided on the clamping pin 212, and the design freedom of the base portion 211 is relatively high. This allows for a more optimized configuration of the heating portion 25. Alternatively, the heating plate 251 can be provided between the upper surface of the base portion 211 and the lower surface 92 of the substrate 9, and directly facing the lower surface 92 of the substrate 9 in the vertical direction (i.e., without any other components in between). In this case, a heating plate moving mechanism can be provided to move the heating plate 251 in the vertical direction, and the distance between the heating plate 251 and the lower surface 92 of the substrate 9 can be made variable.

[0218] In the substrate processing apparatuses 1 and 1a, the shape and arrangement of the heating plate 251 are not limited to the examples described above, and various modifications can be made. For example, the outer diameter of the heating plate 251 may be slightly larger than or approximately equal to the diameter of the substrate 9. Furthermore, the heating section 25 for heating the substrate 9 does not necessarily have a heating plate 251, and the structure of the heating section 25 can be modified in various ways. For example, the heating section 25 may replace the heating plate 251 and be equipped with a lamp that heats the substrate 9 by irradiating light onto the lower surface 92 of the substrate 9.

[0219] In substrate processing apparatus 1, during the rinsing process in step S15, rinsing liquid may be supplied to the upper surface 91 of substrate 9 from a nozzle different from nozzle 51. The same applies to substrate processing apparatus 1a.

[0220] In the substrate processing apparatus 1, the electrical connection between the first electrode 61 and the power supply unit 63 does not necessarily have to be non-contact. For example, the first electrode 61 and the power supply unit 63 can be mechanically and electrically connected via a slip ring or the like provided on the shaft 217. The same applies to the first electrode 61a of the substrate processing apparatus 1a. In this case, the first transmission unit 64 and the second transmission unit 65 can also be omitted.

[0221] In substrate processing apparatus 1, the switching period of the applied voltage can also be less than 0.05 seconds. Furthermore, in substrate processing apparatus 1, it is not necessary to switch the applied voltage; the applied voltage can be kept constant. The same applies to substrate processing apparatus 1a.

[0222] The substrate holding portion 21 does not necessarily have to be a mechanical chuck, but can be a chuck with various structures. For example, the substrate holding portion 21 can also be a vacuum chuck that adsorbs and holds the substrate 9 by directly contacting the lower surface 92 of the substrate 9. In this case, for example, the upper surface of the vacuum chuck that contacts the lower surface 92 of the substrate 9 is a first electrode that is approximately circular, and the substrate 9 is electrically connected to the first electrode by directly contacting the lower surface 92 of the substrate 9 with the first electrode.

[0223] The substrate processing apparatuses 1 and 1a can also be used to process glass substrates used in flat panel displays such as liquid crystal displays or organic EL (electroluminescence) displays, or glass substrates used in other display devices, in addition to semiconductor substrates. Furthermore, the substrate processing apparatuses 1 and 1a can also be used to process substrates for optical discs, magnetic disks, magneto-optical discs, photomasks, ceramic substrates, and solar cells.

[0224] The components in the described implementation methods and variations can be appropriately combined as long as they do not contradict each other.

[0225] The invention has been described in detail, but the description above is illustrative and not limiting. Therefore, it can be said that various modifications and forms can be achieved without departing from the scope of the invention.

[0226] [Explanation of Symbols]

[0227] 1, 1a: Substrate processing apparatus

[0228] 8: Control Department

[0229] 9: Substrate

[0230] 21: Substrate holding section

[0231] 23: Substrate Rotation Mechanism

[0232] 51: Nozzle

[0233] 55: Nozzle moving mechanism

[0234] 61, 61a: First electrode

[0235] 62: Second electrode

[0236] 63: Power Supply Section

[0237] 91: (Substrate) Upper surface

[0238] 93: Pattern

[0239] 95: concave part

[0240] 96: The membrane being treated

[0241] 942: Sidewall Surface

[0242] J1: Central axis

[0243] S11~S16: Steps.

Claims

1. A substrate processing apparatus for etching a substrate, comprising: The substrate holding section holds the substrate with the film to be processed on its upper surface in a horizontal state; A substrate rotation mechanism that allows the substrate holding portion to rotate about a central axis in the vertical direction; A nozzle supplies etching solution from above the substrate toward the upper surface of the substrate and brings it into contact with the film being treated. A nozzle moving mechanism that causes the nozzle to swing horizontally between the center and the periphery of the rotating substrate above it. The first electrode is electrically connected to the substrate; The second electrode is electrically connected to the treatment liquid ejected from the nozzle; The power supply unit applies a voltage between the first electrode and the second electrode; as well as The control unit controls the substrate rotation mechanism, the nozzle, and the power supply unit; and Under the control of the control unit, while the processing liquid is continuously supplied from the nozzle to the upper surface of the substrate and a voltage is applied between the first electrode and the second electrode, the rotational speed of the substrate repeatedly switches between different first and second rotational speeds at a predetermined rotational speed switching cycle, wherein the nozzle oscillates above the rotating substrate.

2. The substrate processing apparatus according to claim 1, wherein Under the control of the control unit, in parallel with the switching of the substrate's rotational speed, the applied voltage repeatedly switches between different first and second voltages at a predetermined voltage switching cycle. Consequently, the potential of the sidewall surface of the recesses forming the pattern on the substrate repeatedly switches between a first potential and a second potential lower than the first potential. The first potential is above 0 V. The second potential is below 0 V.

3. The substrate processing apparatus according to claim 2, wherein The voltage switching cycle is 0.05 seconds or more.

4. The substrate processing apparatus according to claim 2, wherein The speed switching cycle is an integer multiple of the voltage switching cycle.

5. The substrate processing apparatus according to claim 4, wherein The speed switching cycle is an even multiple of the voltage switching cycle.

6. The substrate processing apparatus according to any one of claims 2 to 5, wherein The switching of the substrate's rotational speed and the switching of the applied voltage are performed simultaneously under the control of the control unit.

7. A substrate processing method, comprising etching a substrate, including the following steps: a) Hold the substrate with the film to be treated on its upper surface in a horizontal position; b) Continuously supplying etching solution from a nozzle to the upper surface of the substrate, wherein the nozzle is above the substrate rotating about a central axis in the up-down direction and oscillating horizontally between the center and the periphery of the substrate. c) In parallel with step b), the rotational speed of the substrate is repeatedly switched between two different rotational speeds, a predetermined rotational speed switching cycle; and d) In parallel with step c), a voltage is applied between the substrate and the processing liquid ejected from the nozzle, and the applied voltage is repeatedly switched between different first and second voltages at a predetermined voltage switching cycle, thereby causing the potential of the sidewall surface of the recesses forming the pattern on the substrate to repeatedly switch between a first potential and a second potential lower than the first potential; and The first potential is above 0 V. The second potential is below 0 V.

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