Substrate processing method and substrate processing device

Abstract

An alkaline etching solution containing TMAH, hydrogen peroxide and water but not containing a hydrogen fluoride compound is prepared by mixing TMAH, hydrogen peroxide and water. The prepared etching solution is supplied to a substrate with a polysilicon film and a silicon oxide film exposed, and the polysilicon film is etched while suppressing etching of the silicon oxide film.

Description

Technical Field

[0001] The present invention relates to a substrate processing method and a substrate processing device for processing a substrate. The substrate to be processed includes, for example, a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for an optical disk, a substrate for a magnetic disk, a substrate for an optical magneto-magnetic disk, a substrate for a photomask, a ceramic substrate, a substrate for a solar cell, a substrate for an organic EL (electroluminescence) display device, and the like. Background Art

[0002] In the manufacturing process of semiconductor devices, liquid crystal display devices, etc., a substrate processing device is used to process substrates such as semiconductor wafers and glass substrates for liquid crystal display devices. Patent document 1 discloses a substrate processing device that supplies TMAH (tetramethylammonium hydroxide) to a substrate to etch a polysilicon film formed on the substrate.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-258391 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the manufacturing process of semiconductor devices, liquid crystal display devices, etc., an etching solution such as TMAH is supplied to a substrate with a polysilicon film and a silicon oxide film exposed, and the polysilicon film is etched while suppressing etching of the silicon oxide film.

[0008] The polycrystalline silicon film is composed of a large number of tiny silicon single crystals. The silicon single crystal shows anisotropy with respect to TMAH. That is, the etching speed when TMAH is supplied to the silicon single crystal varies depending on the crystal plane of silicon (etching anisotropy). The orientation of the crystal plane exposed on the surface of the polycrystalline silicon film is various, and varies depending on the location of the polycrystalline silicon film. In addition, the orientation of the crystal plane exposed on the surface of the polycrystalline silicon film varies depending on the polycrystalline silicon film.

[0009] Since silicon single crystals are anisotropic, when a polysilicon film is etched using TMAH, the amount of etching of the polysilicon film varies depending on the location of the polysilicon film (although only slightly). When multiple polysilicon films are etched using TMAH, the amount of etching of the polysilicon film also varies depending on the polysilicon film (although only slightly). With the miniaturization of the pattern formed on the substrate, there are cases where even this degree of uneven etching is not allowed.

[0010] Therefore, one of the objects of the present invention is to provide a substrate processing method and a substrate processing apparatus capable of uniformly etching a polysilicon film while suppressing etching of a silicon oxide film.

[0011] Means for solving problems

[0012] One embodiment of the present invention provides a substrate processing method, which includes the following steps: an etching solution preparation step, in which an organic base, an oxidant and water are mixed to prepare an alkaline etching solution containing an organic base, an oxidant and water but not containing a hydrogen fluoride compound; and a selective etching step, in which the etching solution prepared in the etching solution preparation step is supplied to a substrate with a polycrystalline silicon film and a silicon oxide film exposed, and the polycrystalline silicon film is etched while the etching of the silicon oxide film is suppressed.

[0013] According to this configuration, an alkaline etching solution containing an organic base, an oxidant, and water is supplied to a substrate where a polysilicon film and a silicon oxide film are exposed. The etching solution is a liquid that etches polysilicon without etching or substantially etching silicon oxide. The etching rate of silicon oxide is lower than the etching rate of polysilicon. Therefore, the polysilicon film can be selectively etched.

[0014] The etching solution supplied to the substrate contacts the surface of the polycrystalline silicon film. The surface of the polycrystalline silicon film is composed of a large number of tiny silicon single crystals. The oxidant contained in the etching solution reacts with the surface of the large number of tiny silicon single crystals to generate silicon oxide. Therefore, if the etching solution contains an oxidant, the etching rate of the polycrystalline silicon film is reduced.

[0015] However, the oxidant contained in the etching solution does not react uniformly with the multiple crystal faces of the silicon single crystal, but preferentially reacts with the crystal faces with high active energy among these crystal faces. Therefore, the etching rate of the crystal faces with high active energy is relatively greatly reduced, and the difference in etching rate of each face orientation is reduced. As a result, the anisotropy of the silicon single crystal relative to the etching solution is reduced. That is, the etching of the silicon single crystal constituting the polycrystalline silicon film is close to isotropic.

[0016] In addition, the etching solution does not contain a hydrogen fluoride compound. The hydrogen fluoride compound reacts with the silicon oxide film and dissolves the silicon oxide film in the etching solution. The silicon oxide generated by the reaction of the polysilicon film and the oxidant also reacts with the hydrogen fluoride compound and dissolves in the etching solution. Therefore, by excluding the hydrogen fluoride compound from the components of the etching solution, it is possible to prevent the selectivity (etching speed of the polysilicon film / etching speed of the silicon oxide film) from being reduced, and it is possible to prevent the effect caused by the oxidant from being reduced. As a result, the polysilicon film can be etched uniformly while suppressing the etching of the silicon oxide film.

[0017] It should be noted that hydrogen fluoride compounds are substances different from organic bases (anhydrous substances), oxidants, and water. Hydrogen fluoride compounds refer to compounds containing HF in the chemical formula. Hydrogen fluoride (HF) is included in hydrogen fluoride compounds.

[0018] In this embodiment, at least one of the following features may be added to the above-mentioned substrate processing method.

[0019] The etching solution preparation step is a step of preparing an alkaline liquid composed of the organic base, the oxidizing agent, and the water.

[0020] According to this configuration, an alkaline etching solution containing only an organic base, an oxidizing agent, and water, and not containing any other components, is supplied to a substrate where a polycrystalline silicon film and a silicon oxide film are exposed. As a result, the difference in etching speed of each face orientation of the silicon single crystal can be reduced, and the anisotropy of the silicon single crystal constituting the polycrystalline silicon film can be reduced. Therefore, the polycrystalline silicon film can be uniformly etched while suppressing the etching of the silicon oxide film.

[0021] The above-mentioned substrate includes: a stacked film, which includes a plurality of the above-mentioned polysilicon films and a plurality of the above-mentioned silicon oxide films stacked in the thickness direction of the above-mentioned substrate in a manner that the above-mentioned polysilicon films and the above-mentioned silicon oxide films are alternately stacked; and a recessed portion, which is recessed from the outermost surface of the above-mentioned substrate along the thickness direction of the above-mentioned substrate and penetrates the above-mentioned plurality of polysilicon films and the above-mentioned plurality of silicon oxide films, and the above-mentioned selective etching process includes a process of supplying the above-mentioned etching solution into at least the above-mentioned recessed portion.

[0022] According to this configuration, the side surfaces of the polysilicon film and the silicon oxide film included in the stacked film are exposed on the side surfaces of the recessed portion formed in the substrate. The etching liquid is supplied into the recessed portion of the substrate. As a result, the side surfaces of the plurality of polysilicon films are etched and moved along the surface direction of the substrate (so-called side etching). That is, a plurality of recesses (recesses) are formed in the recessed portion, which are recessed from the side surfaces of the plurality of silicon oxide films along the surface direction of the substrate.

[0023] When the anisotropy of silicon single crystal with respect to the etching solution is high, the etching rate of the polysilicon film is slightly different depending on the polysilicon film. In this case, the depth of the notch formed in the concave portion (the distance in the surface direction of the substrate) will be different depending on the notch. Therefore, by including an oxidant in the etching solution, the difference in etching rate between multiple polysilicon films can be reduced, and the deviation in notch depth can be suppressed.

[0024] The substrate processing method further includes, before the selective etching step, a natural oxide film removing step of supplying an oxide film removing solution to the substrate to remove a natural oxide film of the polysilicon film.

[0025] According to this configuration, an oxide film removing liquid is supplied to the substrate, and the natural oxide film of the polycrystalline silicon film is removed from the surface layer of the polycrystalline silicon film. Then, an etching liquid is supplied to the substrate, and the polycrystalline silicon film is selectively etched. The natural oxide film of the polycrystalline silicon film is mainly composed of silicon oxide. The etching liquid is a liquid that etches the polycrystalline silicon without etching or substantially etching silicon oxide. Therefore, by removing the natural oxide film of the polycrystalline silicon film in advance, the polycrystalline silicon film can be etched efficiently.

[0026] The polysilicon film is a thin film obtained by performing a plurality of steps including: a deposition step of depositing polysilicon; and a heat treatment step of heating the polysilicon deposited in the deposition step.

[0027] According to this configuration, a polycrystalline silicon film that has undergone a heat treatment process (in which the deposited polycrystalline silicon is heated) is etched by an alkaline etching solution containing an oxidant. If the deposited polycrystalline silicon is heated under appropriate conditions, the particle size (grain size) of the polycrystalline silicon increases. Therefore, compared with the case where the heat treatment process is not performed, the silicon single crystals constituting the polycrystalline silicon film are enlarged. This means that the number of silicon single crystals exposed on the surface of the polycrystalline silicon film is reduced, and the influence of anisotropy is increased. Therefore, by supplying an etching solution containing an oxidant to such a polycrystalline silicon film, the influence of anisotropy can be effectively reduced.

[0028] The etching solution preparation step includes a dissolved oxygen concentration changing step of reducing the dissolved oxygen concentration of the etching solution.

[0029] According to this configuration, an etching solution with a reduced dissolved oxygen concentration is supplied to the substrate. As described above, the oxidant reduces the anisotropy of the silicon single crystal constituting the polycrystalline silicon film, but also reduces the etching rate of the polycrystalline silicon film. On the other hand, if the dissolved oxygen concentration of the etching solution is reduced, the etching rate of the polycrystalline silicon film is increased. Therefore, by supplying an etching solution with a reduced dissolved oxygen concentration to the substrate, the anisotropy of the silicon single crystal can be reduced while suppressing the reduction in the etching rate of the polycrystalline silicon film.

[0030] The substrate processing method further includes an atmospheric oxygen concentration changing step of reducing the oxygen concentration in an atmosphere in contact with the etching solution held on the substrate.

[0031] According to this configuration, the etching solution is supplied to the substrate in a state where the oxygen concentration in the atmosphere is low. As a result, the amount of oxygen dissolved in the etching solution from the atmosphere is reduced, and the increase in the dissolved oxygen concentration is suppressed. As described above, the oxidant reduces the anisotropy of the silicon single crystal constituting the polycrystalline silicon film, but also reduces the etching rate of the polycrystalline silicon film. If the dissolved oxygen concentration of the etching solution increases, the etching rate of the polycrystalline silicon film is further reduced. Therefore, by reducing the oxygen concentration in the atmosphere, it is possible to suppress a further decrease in the etching rate.

[0032] The etching solution preparation step includes an oxidant concentration changing step of changing the concentration of the oxidant in the etching solution.

[0033] According to this configuration, the concentration of the oxidant in the etching solution is changed. When an oxidant (even a very small amount) is added to an etching solution containing an organic base and water, the difference in etching speed between multiple crystal planes is reduced, and the anisotropy of the silicon single crystal constituting the polysilicon film is reduced. The difference in etching speed decreases as the concentration of the oxidant increases. On the other hand, the etching speed of the polysilicon film decreases as the concentration of the oxidant increases. If the reduction of anisotropy is prioritized, the concentration of the oxidant can be increased. If the etching speed is prioritized, the concentration of the oxidant can be reduced. Therefore, the etching of the polysilicon film can be controlled by changing the concentration of the oxidant.

[0034] Another embodiment of the present invention provides a substrate processing device, which includes: a substrate holding unit that holds a substrate with a polysilicon film and a silicon oxide film exposed; an etching solution preparation unit that prepares an alkaline etching solution containing an organic base, an oxidant and water but does not contain a hydrogen fluoride compound by mixing an organic base, an oxidant and water; an etching solution supply unit that supplies the etching solution prepared by the etching solution preparation unit to the substrate held by the substrate holding unit; and a control device that controls the etching solution preparation unit and the etching solution supply unit.

[0035] The control device executes the following steps: an etching solution preparation step, causing the etching solution preparation unit to prepare the etching solution; and a selective etching step, causing the etching solution supply unit to supply the etching solution to the substrate to etch the polysilicon film while suppressing the etching of the silicon oxide film. According to this configuration, the same effect as that described in relation to the aforementioned substrate processing method can be obtained.

[0036] In this embodiment, at least one of the following features may be added to the substrate processing apparatus.

[0037] The etching solution preparation unit is a unit for preparing an alkaline liquid formed of the organic base, the oxidant, and the water. According to this configuration, the same effects as those described above with respect to the substrate processing method can be obtained.

[0038] The substrate includes: a stacked film including a plurality of polysilicon films and a plurality of silicon oxide films stacked in a thickness direction of the substrate in a manner that the polysilicon films and the silicon oxide films are alternately stacked; and a recessed portion recessed from the outermost surface of the substrate in the thickness direction of the substrate and penetrating the plurality of polysilicon films and the plurality of silicon oxide films, and the etching liquid supply unit includes a unit for supplying the etching liquid at least into the recessed portion. According to this configuration, the same effect as that described in relation to the aforementioned substrate processing method can be obtained.

[0039] The substrate processing apparatus further includes an oxide film removal liquid supply unit, which supplies the oxide film removal liquid to the substrate held by the substrate holding unit, and the control unit further performs a natural oxide film removal step: before the selective etching step, the oxide film removal liquid supply unit supplies the oxide film removal liquid to the substrate, thereby removing the natural oxide film of the polysilicon film. According to this configuration, the same effect as that described in relation to the aforementioned substrate processing method can be obtained.

[0040] The polysilicon film is a thin film obtained by performing the following multiple steps, the multiple steps including: a deposition step of depositing polysilicon; and a heat treatment step of heating the polysilicon deposited in the deposition step. According to this configuration, the same effect as that described in the above substrate processing method can be obtained.

[0041] The etching solution preparation unit includes a dissolved oxygen concentration changing unit for reducing the dissolved oxygen concentration of the etching solution. According to this configuration, the same effects as those described above with respect to the substrate processing method can be obtained.

[0042] The substrate processing apparatus further includes an atmospheric oxygen concentration changing unit for reducing the oxygen concentration in the atmosphere in contact with the etching solution held on the substrate. According to this configuration, the same effects as those described above with respect to the substrate processing method can be obtained.

[0043] The etching solution preparation unit includes an oxidant concentration changing unit for changing the concentration of the oxidant in the etching solution. According to this configuration, the same effects as those described above with respect to the aforementioned substrate processing method can be obtained.

[0044] The above and other objects, features and effects of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] [ Figure 1 ] is a schematic diagram of a substrate processing device involved in one embodiment of the present invention viewed from above.

[0046] [ Figure 2 ] is a schematic diagram of the interior of a processing unit of a substrate processing apparatus when viewed horizontally.

[0047] [ Figure 3 ] Figure 2 A magnified image of a portion of the image.

[0048] [ Figure 4 ] is a schematic diagram showing a chemical solution preparation unit for preparing a chemical solution to be supplied to a substrate, and a dissolved oxygen concentration changing unit for adjusting the dissolved oxygen concentration of the chemical solution.

[0049] [ Figure 5 ] is a block diagram showing the hardware of the control device.

[0050] [ Figure 6 ] is a schematic diagram showing an example of a cross section of a substrate processed using a substrate processing apparatus.

[0051] [ Figure 7 ] is a process diagram for illustrating an example of substrate processing performed using a substrate processing apparatus.

[0052] [ Figure 8 ] is a coordinate diagram showing the relationship between the concentration of hydrogen peroxide in the etching solution and the etching rate of each crystal plane of silicon.

[0053] [ Fig. 9 ] is a schematic diagram showing a drug solution preparation unit involved in other embodiments of the present invention. DETAILED DESCRIPTION

[0054] Figure 1 It is a schematic diagram of a substrate processing apparatus 1 according to an embodiment of the present invention as viewed from above.

[0055] The substrate processing device 1 is a single-wafer device that processes disc-shaped substrates W such as semiconductor wafers one by one. The substrate processing device 1 includes: a loading port LP that holds a carrier C that stores one or more substrates W constituting a batch; a plurality of processing units 2 that process the substrates W transported from the carrier C on the loading port LP using a processing fluid such as a processing liquid and a processing gas; a transport robot that transports the substrates W between the carrier C on the loading port LP and the processing unit 2; and a control device 3 that controls the substrate processing device 1.

[0056] The transport robot includes an indexer robot IR that carries substrates W in and out of a carrier C on a load port LP, and a central robot CR that carries substrates W in and out of a plurality of processing units 2. The indexer robot IR carries substrates W between the load port LP and the central robot CR, and the central robot CR carries substrates W between the indexer robot IR and the processing units 2. The indexer robot IR and the central robot CR include arms H1 and H2 that support the substrates W.

[0057] Figure 2 It is a schematic diagram showing the interior of a processing unit 2 included in a substrate processing apparatus 1 when viewed horizontally. Figure 3 For the general Figure 2 A magnified image of a portion of the image. Figure 2 The lifting frame 32 and the blocking member 33 are shown in the state of being in the lower position. Figure 3 The state where the lifting frame 32 and the blocking member 33 are located at the upper position is shown. In the following description, TMAH refers to an aqueous solution unless otherwise specified.

[0058] The processing unit 2 includes: a box-shaped chamber 4 having an internal space; a rotating chuck 10 that horizontally holds a substrate W in the chamber 4 and rotates it around a vertical rotation axis A1 passing through the center of the substrate W; and a cylindrical processing cup 23 that surrounds the rotating chuck 10 around the rotation axis A1.

[0059] The chamber 4 includes: a box-shaped partition wall 6, which is provided with a loading and unloading port 6b for the substrate W to pass through; and a gate 7, which opens and closes the loading and unloading port 6b. The chamber 4 also includes a rectifying plate 8, which is arranged below the air supply port 6a opened at the top surface of the partition wall 6. The FFU5 (fan filter unit) that transports clean air (air filtered by a filter) is arranged on the air supply port 6a. The exhaust duct 9 that exhausts the gas in the chamber 4 is connected to the processing cup 23. The air supply port 6a is arranged at the upper end of the chamber 4, and the exhaust duct 9 is arranged at the lower end of the chamber 4. A part of the exhaust duct 9 is arranged outside the chamber 4.

[0060] The rectifying plate 8 divides the internal space of the partition wall 6 into an upper space Su above the rectifying plate 8 and a lower space SL below the rectifying plate 8. The upper space Su between the top surface of the partition wall 6 and the upper surface of the rectifying plate 8 is a diffusion space for the diffusion of clean air. The lower space SL between the lower surface of the rectifying plate 8 and the bottom surface of the partition wall 6 is a processing space for processing the substrate W. The spin chuck 10 and the processing cup 23 are arranged in the lower space SL. The vertical distance from the bottom surface of the partition wall 6 to the lower surface of the rectifying plate 8 is longer than the vertical distance from the upper surface of the rectifying plate 8 to the top surface of the partition wall 6.

[0061] The FFU5 delivers clean air to the upper space Su via the air supply port 6a. The clean air supplied to the upper space Su collides with the rectifying plate 8 and diffuses in the upper space Su. The clean air in the upper space Su passes through a plurality of through holes that penetrate the rectifying plate 8 from top to bottom, and flows downward from the entire area of ​​the rectifying plate 8. The clean air supplied to the lower space SL is sucked into the processing cup 23, passes through the exhaust pipe 9, and is discharged from the lower end of the chamber 4. As a result, a uniform downflow of clean air is formed in the lower space SL, flowing downward from the rectifying plate 8. The processing of the substrate W is performed in a state where a downflow of clean air is formed.

[0062] The spin chuck 10 includes: a disk-shaped spin base 12 held in a horizontal posture; a plurality of chuck pins 11 holding the substrate W in a horizontal posture above the spin base 12; a rotation shaft 13 extending downward from the center of the spin base 12; and a rotation motor 14 that rotates the spin base 12 and the plurality of chuck pins 11 by rotating the rotation shaft 13. The spin chuck 10 is not limited to a clamping chuck in which the plurality of chuck pins 11 are in contact with the outer peripheral surface of the substrate W, but may be a vacuum chuck in which the back surface (lower surface) of the substrate W, which is a non-device forming surface, is adsorbed to the upper surface 12u of the spin base 12 to hold the substrate W in a horizontal state.

[0063] The rotating base 12 includes an upper surface 12u disposed below the substrate W. The upper surface 12u of the rotating base 12 is parallel to the lower surface of the substrate W. The upper surface 12u of the rotating base 12 is an opposite surface to the lower surface of the substrate W. The upper surface 12u of the rotating base 12 is an annular shape surrounding the rotation axis A1. The outer diameter of the upper surface 12u of the rotating base 12 is larger than the outer diameter of the substrate W. The chuck pins 11 protrude upward from the outer periphery of the upper surface 12u of the rotating base 12. The chuck pins 11 are held on the rotating base 12. The substrate W is held on the plurality of chuck pins 11 in a state where the lower surface of the substrate W is separated from the upper surface 12u of the rotating base 12.

[0064] The processing unit 2 includes a lower surface nozzle 15 that sprays the processing liquid toward the center of the lower surface of the substrate W. The lower surface nozzle 15 includes: a nozzle disk portion disposed between the upper surface 12u of the spin base 12 and the lower surface of the substrate W; and a nozzle cylindrical portion extending downward from the nozzle disk portion. The liquid spray port 15p of the lower surface nozzle 15 opens at the center of the upper surface of the nozzle disk portion. When the substrate W is held on the spin chuck 10, the liquid spray port 15p of the lower surface nozzle 15 is opposite to the center of the lower surface of the substrate W in the vertical direction.

[0065] The substrate processing apparatus 1 includes: a lower rinse liquid pipe 16 for guiding the rinse liquid to the lower surface nozzle 15; and a lower rinse liquid valve 17 installed on the lower rinse liquid pipe 16. When the lower rinse liquid valve 17 is opened, the rinse liquid guided by the lower rinse liquid pipe 16 is ejected upward from the lower surface nozzle 15 and supplied to the central part of the lower surface of the substrate W. The rinse liquid supplied to the lower surface nozzle 15 is pure water (deionized water: DIW (Deionized Water)). The rinse liquid supplied to the lower surface nozzle 15 is not limited to pure water, and can be any of IPA (isopropyl alcohol), carbonated water, electrolytic ion water, hydrogen-rich water, ozone water, and a hydrochloric acid aqueous solution with a diluted concentration (for example, about 1 to 100 ppm).

[0066] Although not shown, the lower rinse liquid valve 17 includes: a valve body, which is provided with an internal flow path for liquid flow and an annular valve seat surrounding the internal flow path; a valve core, which can move relative to the valve seat; and an actuator, which moves the valve core between a closed position where the valve core contacts the valve seat and an open position where the valve core is separated from the valve seat. The same is true for other valves. The actuator can be a pneumatic actuator or an electric actuator, or an actuator other than these. The control device 3 opens and closes the lower rinse liquid valve 17 by controlling the actuator.

[0067] The outer circumferential surface of the lower surface nozzle 15 and the inner circumferential surface of the rotating base 12 form a lower cylindrical passage 19 extending in the vertical direction. The lower cylindrical passage 19 includes a lower central opening 18 opened at the central portion of the upper surface 12u of the rotating base 12. The lower central opening 18 is arranged below the nozzle disk portion of the lower surface nozzle 15. The substrate processing apparatus 1 includes: a lower gas pipe 20 that guides the inert gas supplied to the lower central opening 18 via the lower cylindrical passage 19; a lower gas valve 21 that is installed on the lower gas pipe 20; and a lower gas flow rate regulating valve 22 that changes the flow rate of the inert gas supplied from the lower gas pipe 20 to the lower cylindrical passage 19.

[0068] The inert gas supplied from the lower gas pipe 20 to the lower cylindrical passage 19 is nitrogen. The inert gas is not limited to nitrogen, and may be other inert gases such as helium and argon. These inert gases are low-oxygen gases having an oxygen concentration lower than that in air (about 21 vol%).

[0069] When the lower gas valve 21 is opened, the nitrogen gas supplied from the lower gas pipe 20 to the lower cylindrical passage 19 is ejected upward from the lower central opening 18 at a flow rate corresponding to the opening of the lower gas flow rate control valve 22. Then, the nitrogen gas flows radially in all directions between the lower surface of the substrate W and the upper surface 12u of the spin base 12. As a result, the space between the substrate W and the spin base 12 is filled with nitrogen gas, and the oxygen concentration in the atmosphere is reduced. The oxygen concentration in the space between the substrate W and the spin base 12 changes according to the opening of the lower gas valve 21 and the lower gas flow rate control valve 22. The lower gas valve 21 and the lower gas flow rate control valve 22 are included in an atmosphere oxygen concentration changing unit that changes the oxygen concentration in the atmosphere in contact with the substrate W.

[0070] The processing cup 23 includes: a plurality of protective covers 25 that receive liquid discharged from the substrate W to the outside; a plurality of cups 26 that receive liquid guided downward by the plurality of protective covers 25; and a cylindrical outer wall member 24 that surrounds the plurality of protective covers 25 and the plurality of cups 26. Figure 2 An example in which two protective covers 25 and two cups 26 are provided is shown.

[0071] The shield 25 includes: a cylindrical shield barrel portion 25b, which surrounds the rotating chuck 10; and an annular shield top portion 25a, which extends obliquely upward from the upper end of the shield barrel portion 25b toward the rotation axis A1. A plurality of shield top portions 25a overlap up and down, and a plurality of shield barrel portions 25b are arranged in concentric circles. A plurality of cups 26 are respectively arranged below the plurality of shield barrel portions 25b. The cups 26 form an annular liquid receiving tank that opens upward.

[0072] The processing unit 2 includes a protective cover lifting unit 27 for lifting and lowering a plurality of protective covers 25. The protective cover lifting unit 27 positions the protective cover 25 at any position from an upper position to a lower position. The upper position is when the upper end 25u of the protective cover 25 is arranged at a position higher than the holding position at which the substrate W held on the spin chuck 10 is arranged. The lower position is when the upper end 25u of the protective cover 25 is arranged at a position lower than the holding position. The annular upper end of the protective cover top 25a is equivalent to the upper end 25u of the protective cover 25. In a top view, the upper end 25u of the protective cover 25 surrounds the substrate W and the spin base 12.

[0073] When the processing liquid is supplied to the substrate W while the spin chuck 10 is rotating the substrate W, the processing liquid supplied to the substrate W is thrown off around the substrate W. When the processing liquid is supplied to the substrate W, the upper end 25u of at least one protective cover 25 is arranged above the substrate W. Therefore, the processing liquid such as the chemical solution and the rinsing liquid discharged around the substrate W is received by any protective cover 25 and guided to the cup 26 corresponding to the protective cover 25.

[0074] like Figure 3 As shown, the processing unit 2 includes: a lifting frame 32 disposed above the rotating chuck 10; a blocking member 33 suspended downward from the lifting frame 32; a central nozzle 45 inserted into the blocking member 33; and a blocking member lifting unit 31 that lifts and lowers the blocking member 33 and the central nozzle 45 by lifting and lowering the lifting frame 32. The lifting frame 32, the blocking member 33, and the central nozzle 45 are disposed below the rectifying plate 8.

[0075] The blocking member 33 includes: a disk portion 36 disposed above the rotating chuck 10; and a cylindrical portion 37 extending downward from the outer peripheral portion of the disk portion 36. The blocking member 33 includes a cup-shaped inner surface that is concave upward. The inner surface of the blocking member 33 includes a lower surface 36L of the disk portion 36 and an inner peripheral surface 37i of the cylindrical portion 37. Hereinafter, the lower surface 36L of the disk portion 36 is sometimes referred to as the lower surface 36L of the blocking member 33.

[0076] The lower surface 36L of the circular plate portion 36 is an opposing surface to the upper surface of the substrate W. The lower surface 36L of the circular plate portion 36 is parallel to the upper surface of the substrate W. The inner circumferential surface 37i of the cylindrical portion 37 extends downward from the outer peripheral edge of the lower surface 36L of the circular plate portion 36. The inner diameter of the cylindrical portion 37 increases as it approaches the lower end of the inner circumferential surface 37i of the cylindrical portion 37. The inner diameter of the lower end of the inner circumferential surface 37i of the cylindrical portion 37 is larger than the diameter of the substrate W. The inner diameter of the lower end of the inner circumferential surface 37i of the cylindrical portion 37 may also be larger than the outer diameter of the rotation base 12. The blocking member 33 is arranged at the lower position ( Figure 2 When the substrate W is in the position shown in the figure, it is surrounded by the inner peripheral surface 37i of the cylindrical portion 37.

[0077] The lower surface 36L of the circular plate portion 36 is annular and surrounds the rotation axis A1. The inner peripheral edge of the lower surface 36L of the circular plate portion 36 is formed with an upper central opening 38 opened at the central portion of the lower surface 36L of the circular plate portion 36. The inner peripheral surface of the blocking member 33 is formed with a through hole extending upward from the upper central opening 38. The through hole of the blocking member 33 penetrates the blocking member 33 from top to bottom. The center nozzle 45 is inserted into the through hole of the blocking member 33. The outer diameter of the lower end of the center nozzle 45 is smaller than the diameter of the upper central opening 38.

[0078] The inner circumference of the blocking member 33 is coaxial with the outer circumference of the center nozzle 45. The inner circumference of the blocking member 33 surrounds the outer circumference of the center nozzle 45 at intervals in the radial direction (in the direction orthogonal to the rotation axis A1). The inner circumference of the blocking member 33 and the outer circumference of the center nozzle 45 form an upper cylindrical passage 39 extending up and down. The center nozzle 45 protrudes upward from the lifting frame 32 and the blocking member 33. When the blocking member 33 is suspended downward from the lifting frame 32, the lower end of the center nozzle 45 is arranged at a position higher than the lower surface 36L of the circular plate portion 36. Treatment liquids such as liquid medicine and rinse liquid are sprayed downward from the lower end of the center nozzle 45.

[0079] The blocking member 33 includes: a cylindrical connecting portion 35 extending upward from the circular plate portion 36; and an annular flange portion 34 extending outward from the upper end portion of the connecting portion 35. The flange portion 34 is arranged at a position higher than the circular plate portion 36 and the cylindrical portion 37 of the blocking member 33. The flange portion 34 is parallel to the circular plate portion 36. The outer diameter of the flange portion 34 is smaller than the outer diameter of the cylindrical portion 37. The flange portion 34 is supported by a lower plate 32L of the lifting frame 32 described later.

[0080] The lifting frame 32 includes: an upper plate 32u located above the flange 34 of the blocking member 33; a side ring 32s extending downward from the upper plate 32u and surrounding the flange 34; and an annular lower plate 32L extending inward from the lower end of the side ring 32s and located below the flange 34 of the blocking member 33. The outer periphery of the flange 34 is arranged between the upper plate 32u and the lower plate 32L. The outer periphery of the flange 34 can move up and down between the upper plate 32u and the lower plate 32L.

[0081] The lifting frame 32 and the blocking member 33 include positioning protrusions 41 and positioning holes 42 for restricting relative movement of the lifting frame 32 and the blocking member 33 in the circumferential direction (direction around the rotation axis A1 ) when the blocking member 33 is supported by the lifting frame 32 . Figure 2 The example in which the plurality of positioning protrusions 41 are provided on the lower plate 32L and the plurality of positioning holes 42 are provided on the flange portion 34 is shown. The positioning protrusions 41 may be provided on the flange portion 34 and the positioning holes 42 may be provided on the lower plate 32L.

[0082] A plurality of positioning protrusions 41 are arranged on a circle having a center arranged on the rotation axis A1. Similarly, a plurality of positioning holes 42 are arranged on a circle having a center arranged on the rotation axis A1. The plurality of positioning holes 42 are arranged circumferentially with the same regularity as the plurality of positioning protrusions 41. The positioning protrusions 41 protruding upward from the upper surface of the lower plate 32L are inserted into the positioning holes 42 extending upward from the lower surface of the flange portion 34. Thus, the movement of the blocking member 33 relative to the lifting frame 32 in the circumferential direction is restricted.

[0083] The blocking member 33 includes a plurality of upper supporting portions 43 protruding downward from the inner surface of the blocking member 33. The spin chuck 10 includes a plurality of lower supporting portions 44 that respectively support the plurality of upper supporting portions 43. The plurality of upper supporting portions 43 are surrounded by the cylindrical portion 37 of the blocking member 33. The lower end of the upper supporting portion 43 is arranged above the lower end of the cylindrical portion 37. The radial distance from the rotation axis A1 to the upper supporting portion 43 is greater than the radius of the substrate W. Similarly, the radial distance from the rotation axis A1 to the lower supporting portion 44 is greater than the radius of the substrate W. The lower supporting portion 44 protrudes upward from the upper surface 12u of the spin base 12. The lower supporting portion 44 is arranged outside the chuck pin 11.

[0084] The plurality of upper support portions 43 are arranged on a circle having a center arranged on the rotation axis A1. Similarly, the plurality of lower support portions 44 are arranged on a circle having a center arranged on the rotation axis A1. The plurality of lower support portions 44 are arranged in the circumferential direction with the same regularity as the plurality of upper support portions 43. The plurality of lower support portions 44 rotate around the rotation axis A1 together with the rotating base 12. The rotation angle of the rotating base 12 is changed by the rotating motor 14. When the rotating base 12 is arranged at the reference rotation angle, the plurality of upper support portions 43 overlap with the plurality of lower support portions 44 in a top view.

[0085] The blocking member lifting unit 31 is connected to the lifting frame 32. When the flange 34 of the blocking member 33 is supported by the lower plate 32L of the lifting frame 32, the blocking member 33 is also lowered when the blocking member lifting unit 31 lowers the lifting frame 32. When the rotating base 12 is configured at a reference rotation angle in which the plurality of upper supporting parts 43 overlap the plurality of lower supporting parts 44 in a top view, the lower end of the upper supporting part 43 contacts the upper end of the lower supporting part 44 when the blocking member lifting unit 31 lowers the blocking member 33. Thus, the plurality of upper supporting parts 43 are supported by the plurality of lower supporting parts 44, respectively.

[0086] After the upper support portion 43 of the blocking member 33 contacts the lower support portion 44 of the rotary chuck 10, when the blocking member lifting unit 31 lowers the lifting frame 32, the lower plate 32L of the lifting frame 32 moves downward relative to the flange portion 34 of the blocking member 33. As a result, the lower plate 32L is separated from the flange portion 34, and the positioning protrusion 41 is pulled out from the positioning hole 42. Furthermore, since the lifting frame 32 and the center nozzle 45 move downward relative to the blocking member 33, the height difference between the lower end of the center nozzle 45 and the lower surface 36L of the circular plate portion 36 of the blocking member 33 is reduced. At this time, the lifting frame 32 is arranged at a height (the lower position described later) at which the flange portion 34 of the blocking member 33 does not contact the upper plate 32u of the lifting frame 32.

[0087] The blocking member lifting unit 31 makes the lifting frame 32 located from the upper position ( Figure 3 position shown) to the lower position ( Figure 2 The upper position is a position where the positioning protrusion 41 is inserted into the positioning hole 42 and the flange 34 of the blocking member 33 is in contact with the lower plate 32L of the lifting frame 32. That is, the upper position is a position where the blocking member 33 is suspended downward from the lifting frame 32. The lower position is a position where the lower plate 32L is separated from the flange 34 and the positioning protrusion 41 is pulled out of the positioning hole 42. That is, the lower position is a position where the connection between the lifting frame 32 and the blocking member 33 is released and the blocking member 33 is not in contact with any part of the lifting frame 32.

[0088] When the lifting frame 32 and the blocking member 33 are moved to the lower position, the lower end of the cylindrical portion 37 of the blocking member 33 is arranged below the lower surface of the substrate W, and the space between the upper surface of the substrate W and the lower surface 36L of the blocking member 33 is surrounded by the cylindrical portion 37 of the blocking member 33. Therefore, the space between the upper surface of the substrate W and the lower surface 36L of the blocking member 33 is not only blocked from the atmosphere above the blocking member 33, but also blocked from the atmosphere around the blocking member 33. Thus, the airtightness of the space between the upper surface of the substrate W and the lower surface 36L of the blocking member 33 can be improved.

[0089] Furthermore, when the lifting frame 32 and the blocking member 33 are arranged in the lower position, even if the blocking member 33 is rotated relative to the lifting frame 32 around the rotation axis A1, the blocking member 33 does not collide with the lifting frame 32. When the upper support portion 43 of the blocking member 33 is supported by the lower support portion 44 of the rotating chuck 10, the upper support portion 43 and the lower support portion 44 are engaged, and the relative movement of the upper support portion 43 and the lower support portion 44 in the circumferential direction is restricted. In this state, when the rotary motor 14 rotates, the torque of the rotary motor 14 is transmitted to the blocking member 33 via the upper support portion 43 and the lower support portion 44. Thus, when the lifting frame 32 and the center nozzle 45 are stationary, the blocking member 33 rotates in the same direction and at the same speed as the rotating base 12.

[0090] The central nozzle 45 includes a plurality of liquid outlets for ejecting liquid and a gas outlet for ejecting gas. The plurality of liquid outlets include: a first liquid outlet 46 for ejecting a first liquid, a second liquid outlet 47 for ejecting a second liquid, and an upper rinse liquid outlet 48 for ejecting a rinse liquid. The gas outlet is an upper gas outlet 49 for ejecting an inert gas. The first liquid outlet 46, the second liquid outlet 47, and the upper rinse liquid outlet 48 are open at the lower end of the central nozzle 45. The upper gas outlet 49 is open at the outer peripheral surface of the central nozzle 45.

[0091] The first chemical solution and the second chemical solution are liquids containing at least one of sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, acetic acid, ammonia water, hydrogen peroxide solution, organic acid (such as citric acid, oxalic acid, etc.), organic base (such as TMAH: tetramethylammonium hydroxide, etc.), surfactant, and anticorrosive agent. Sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, acetic acid, ammonia water, hydrogen peroxide solution, citric acid, oxalic acid, and TMAH are etching liquids.

[0092] The first chemical solution and the second chemical solution may be of the same type or of different types. Figure 2 The example in which the first chemical liquid is DHF (dilute hydrofluoric acid) and the second chemical liquid is a mixed liquid of TMAH, hydrogen peroxide (H2O2), and water (H2O) is shown. Figure 2 The examples in which the rinsing liquid supplied to the central nozzle 45 is pure water and the inert gas supplied to the central nozzle 45 is nitrogen are shown in FIG. The rinsing liquid supplied to the central nozzle 45 may be a rinsing liquid other than pure water. The inert gas supplied to the central nozzle 45 may be an inert gas other than nitrogen.

[0093] The substrate processing apparatus 1 is provided with a liquid preparation unit 61 for preparing a second liquid. As described below, the liquid preparation unit 61 prepares an alkaline etching liquid containing TMAH (anhydrous form of TMAH), hydrogen peroxide, and water. The etching liquid is equivalent to the second liquid. The etching liquid is, for example, a liquid having a pH (hydrogen ion index) of 12 or more. The etching liquid may also contain components other than TMAH, hydrogen peroxide, and water.

[0094] TMAH is an example of an organic base. TMAH is also an example of a quaternary ammonium hydroxide solution. The organic base may also be a compound other than TMAH. As organic bases other than TMAH, TEAH (tetraethylammonium hydroxide), TPAH (tetrapropylammonium hydroxide), TBAH (tetrabutylammonium hydroxide) and the like may be cited. They are all included in quaternary ammonium hydroxide.

[0095] Hydrogen peroxide is an example of an oxidizing agent. Aqueous hydrogen peroxide solution (30 vol%) is placed in a tank 62 (see Figure 4 ) is mixed with TMAH. When the volume ratio of anhydrous TMAH to water is 1 to 4 (water is 4), the volume ratio of the aqueous hydrogen peroxide solution added to TMAH is, for example, 0.005 to 1, preferably 0.005 to 0.5. The oxidant may be a liquid or gas other than hydrogen peroxide. For example, ozone gas, as an example of an oxidant, may be dissolved in TMAH instead of hydrogen peroxide.

[0096] The substrate processing apparatus 1 includes: a first chemical liquid pipe 50 for introducing a first chemical liquid to the center nozzle 45; a first chemical liquid valve 51 installed in the first chemical liquid pipe 50; a second chemical liquid pipe 52 for introducing a second chemical liquid to the center nozzle 45; a second chemical liquid valve 53 installed in the second chemical liquid pipe 52; an upper rinse liquid pipe 54 for introducing a rinse liquid to the center nozzle 45; and an upper rinse liquid valve 55 installed in the upper rinse liquid pipe 54. The substrate processing apparatus 1 further includes: an upper gas pipe 56 for introducing a gas to the center nozzle 45; an upper gas valve 57 installed in the upper gas pipe 56; and an upper gas flow rate regulating valve 58 for changing the flow rate of the gas supplied from the upper gas pipe 56 to the center nozzle 45.

[0097] When the first chemical liquid valve 51 is opened, the first chemical liquid is supplied to the central nozzle 45 and is ejected downward from the first chemical liquid ejection port 46 opened at the lower end of the central nozzle 45. When the second chemical liquid valve 53 is opened, the second chemical liquid produced in the chemical liquid preparation unit 61 is supplied to the central nozzle 45 and is ejected downward from the second chemical liquid ejection port 47 opened at the lower end of the central nozzle 45. When the upper rinse liquid valve 55 is opened, the rinse liquid is supplied to the central nozzle 45 and is ejected downward from the upper rinse liquid ejection port 48 opened at the lower end of the central nozzle 45. Thus, the chemical liquid or the rinse liquid is supplied to the upper surface of the substrate W.

[0098] When the upper gas valve 57 is opened, the nitrogen gas guided by the upper gas pipe 56 is supplied to the central nozzle 45 at a flow rate corresponding to the opening of the upper gas flow regulating valve 58, and is ejected obliquely downward from the upper gas ejection port 49 opened at the outer peripheral surface of the central nozzle 45. Then, the nitrogen gas flows circumferentially in the upper tubular passage 39 while flowing downward in the upper tubular passage 39. The nitrogen gas reaching the lower end of the upper tubular passage 39 flows downward from the lower end of the upper tubular passage 39. Then, the nitrogen gas flows radially in all directions in the space between the upper surface of the substrate W and the lower surface 36L of the blocking member 33. Thus, the space between the substrate W and the blocking member 33 is filled with nitrogen, and the oxygen concentration in the atmosphere is reduced. The oxygen concentration of the space between the substrate W and the blocking member 33 is changed according to the opening of the upper gas valve 57 and the upper gas flow regulating valve 58. The upper gas valve 57 and the upper gas flow regulating valve 58 are included in the atmosphere oxygen concentration changing unit.

[0099] Figure 4 1 is a schematic diagram showing a chemical solution preparation unit 61 for preparing a chemical solution to be supplied to a substrate W, and a dissolved oxygen concentration changing unit 67 for adjusting the dissolved oxygen concentration of the chemical solution.

[0100] The chemical solution preparation unit 61 includes a tank 62 for storing an etching solution to be supplied to the substrate W, and a circulation pipe 63 forming a loop-shaped circulation path for circulating the etching solution in the tank 62. The chemical solution preparation unit 61 further includes a pump 64 for conveying the etching solution in the tank 62 to the circulation pipe 63, and a filter 66 for removing foreign matter such as particles from the etching solution flowing in the circulation path. In addition to these, the chemical solution preparation unit 61 may also include a temperature regulator 65 for changing the temperature of the etching solution in the tank 62 by heating or cooling the etching solution.

[0101] The upstream end and the downstream end of the circulation pipe 63 are connected to the tank 62. The upstream end of the second liquid medicine pipe 52 is connected to the circulation pipe 63, and the downstream end of the second liquid medicine pipe 52 is connected to the center nozzle 45. The pump 64, the temperature regulator 65, and the filter 66 are installed on the circulation pipe 63. The temperature regulator 65 can be a heater that heats the liquid at a temperature higher than the room temperature (for example, 20 to 30° C.), or a cooler that cools the liquid at a temperature lower than the room temperature, or can have both heating and cooling functions.

[0102] The pump 64 always delivers the etching liquid in the tank 62 to the circulation pipe 63. The etching liquid is delivered from the tank 62 to the upstream end of the circulation pipe 63, and returns to the tank 62 from the downstream end of the circulation pipe 63. Thus, the etching liquid in the tank 62 circulates in the circulation path. While the etching liquid circulates in the circulation path, the temperature of the etching liquid is adjusted by the temperature regulator 65. Thus, the etching liquid in the tank 62 is maintained at a constant temperature. When the second liquid valve 53 is opened, a part of the etching liquid flowing in the circulation pipe 63 is supplied to the center nozzle 45 via the second liquid pipe 52.

[0103] The substrate processing apparatus 1 is provided with a dissolved oxygen concentration changing unit 67 for adjusting the dissolved oxygen concentration of the etching solution. The dissolved oxygen concentration changing unit 67 includes a gas supply pipe 68 for dissolving the gas into the etching solution in the tank 62 by supplying the gas into the tank 62. The dissolved oxygen concentration changing unit 67 further includes: an inert gas pipe 69 for supplying the inert gas to the gas supply pipe 68; an inert gas valve 70 for opening and closing between an open state in which the inert gas flows from the inert gas pipe 69 into the gas supply pipe 68 and a closed state in which the inert gas is blocked in the inert gas pipe 69; and an inert gas flow rate regulating valve 71 for changing the flow rate of the inert gas supplied from the inert gas pipe 69 to the gas supply pipe 68.

[0104] The gas supply piping 68 is a bubbling piping including a gas ejection port 68p disposed in the etching liquid in the tank 62. When the inert gas valve 70 is opened, that is, when the inert gas valve 70 is switched from a closed state to an open state, an inert gas such as nitrogen is ejected from the gas ejection port 68p at a flow rate corresponding to the opening of the inert gas flow rate regulating valve 71. As a result, a large number of bubbles are formed in the etching liquid in the tank 62, and the inert gas is dissolved in the etching liquid in the tank 62. At this time, dissolved oxygen is discharged from the etching liquid, and the dissolved oxygen concentration of the etching liquid is reduced. The dissolved oxygen concentration of the etching liquid in the tank 62 is changed by changing the flow rate of the nitrogen gas ejected from the gas ejection port 68p.

[0105] In addition to the inert gas piping 69, etc., the dissolved oxygen concentration changing unit 67 may further include: an oxygen-containing gas piping 72 for supplying oxygen-containing gas such as clean air to the gas supply piping 68; an oxygen-containing gas valve 73 that opens and closes between an open state in which the oxygen-containing gas flows from the oxygen-containing gas piping 72 into the gas supply piping 68 and a closed state in which the oxygen-containing gas is blocked in the oxygen-containing gas piping 72; and an oxygen-containing gas flow regulating valve 74 that changes the flow rate of the oxygen-containing gas supplied from the oxygen-containing gas piping 72 to the gas supply piping 68.

[0106] When the oxygen-containing gas valve 73 is opened, air as an example of oxygen-containing gas is ejected from the gas ejection port 68p at a flow rate corresponding to the opening of the oxygen-containing gas flow control valve 74. As a result, a large number of bubbles are formed in the etching liquid in the tank 62, and the air is dissolved in the etching liquid in the tank 62. Air contains oxygen at a ratio of about 21 vol%, while nitrogen does not contain oxygen or contains only a very small amount of oxygen. Therefore, compared with the case where air is not supplied to the tank 62, the dissolved oxygen concentration of the etching liquid in the tank 62 can be increased in a short time. For example, when the dissolved oxygen concentration of the etching liquid becomes too low compared to the set value, air can be intentionally dissolved in the etching liquid in the tank 62.

[0107] The dissolved oxygen concentration changing unit 67 may further include an oxygen concentration meter 75 for measuring the dissolved oxygen concentration of the etching solution. Figure 4 An example is shown in which the oxygen concentration meter 75 is installed in the measuring pipe 76. The oxygen concentration meter 75 may also be installed in the circulation pipe 63. The upstream end of the measuring pipe 76 is connected to the filter 66, and the downstream end of the measuring pipe 76 is connected to the tank 62. The upstream end of the measuring pipe 76 may be connected to the circulation pipe 63. A part of the etching liquid in the circulation pipe 63 flows into the measuring pipe 76 and returns to the tank 62. The oxygen concentration meter 75 measures the dissolved oxygen concentration of the etching liquid flowing into the measuring pipe 76. The opening degree of at least one of the inert gas valve 70, the inert gas flow control valve 71, the oxygen-containing gas valve 73, and the oxygen-containing gas flow control valve 74 is changed according to the measured value of the oxygen concentration meter 75.

[0108] The chemical solution preparation unit 61 includes an oxidant concentration changing unit 77 for changing the concentration of the oxidant in the etching solution. The oxidant concentration changing unit 77 includes an oxidant piping 78 for guiding the oxidant supplied to the tank 62; an oxidant valve 79 for opening and closing the oxidant piping 78; and an oxidant flow rate regulating valve 80 for changing the flow rate of the oxidant supplied from the oxidant piping 78 to the tank 62. When the oxidant valve 79 is opened, an aqueous hydrogen peroxide solution, which is an example of an oxidant, is supplied to the tank 62 at a flow rate corresponding to the oxidant flow rate regulating valve 80. The aqueous hydrogen peroxide solution is mixed with the etching solution in the tank 62 by the flow of the liquid (generated in the tank 62 by the suction force of the pump 64 and the supply of gas). The chemical solution preparation unit 61 may include a stirrer for stirring the liquid in the tank 62.

[0109] The oxidant concentration changing unit 77 including the oxidant valve 79 and the oxidant flow rate regulating valve 80 is controlled by the control device 3. The oxidant valve 79 is closed except when the etching solution including TMAH, hydrogen peroxide and water is prepared and the concentration of hydrogen peroxide is changed. In other words, when the etching solution including TMAH, hydrogen peroxide and water is prepared and the concentration of hydrogen peroxide is changed, the oxidant valve 79 is opened and an appropriate amount of hydrogen peroxide aqueous solution is supplied to the tank 62. As described later, the concentration of hydrogen peroxide in the etching solution is set so that the anisotropy of the silicon single crystal with respect to the etching solution including TMAH, hydrogen peroxide and water is reduced.

[0110] Figure 5 2 is a block diagram showing the hardware of the control device 3 .

[0111] The control device 3 is a computer, which includes a computer main body 81 and a peripheral device 84 connected to the computer main body 81. The computer main body 81 includes: a CPU 82 (central processing unit) that executes various commands; and a main storage device 83 that stores information. The peripheral device 84 includes: an auxiliary storage device 85 that stores information such as a program P; a reading device 86 that reads information from a removable medium M; and a communication device 87 that communicates with other devices such as a host computer.

[0112] The control device 3 is connected to an input device 88 and a display device 89. The input device 88 is operated when an operator such as a user or a maintenance worker inputs information into the substrate processing device 1. The information is displayed on the screen of the display device 89. The input device 88 may be any of a keyboard, a pointing device, and a touch panel, or may be a device other than these. A touch panel display that serves as both the input device 88 and the display device 89 may also be provided in the substrate processing device 1.

[0113] The CPU 82 executes the program P stored in the auxiliary storage device 85. The program P in the auxiliary storage device 85 may be pre-installed in the control device 3, or may be transferred from the removable medium M to the auxiliary storage device 85 via the reading device 86, or may be transferred from an external device such as a host computer to the auxiliary storage device 85 via the communication device 87.

[0114] The auxiliary storage device 85 and the removable medium M are non-volatile memories that retain storage even when power is not supplied. The auxiliary storage device 85 is, for example, a magnetic storage device such as a hard disk drive. The removable medium M is, for example, an optical disk such as a CD or a semiconductor memory such as a memory card. The removable medium M is an example of a computer-readable recording medium on which the program P is recorded.

[0115] The auxiliary storage device 85 stores a plurality of recipes. The recipe is information that specifies the processing content, processing conditions, and processing steps of the substrate W. The plurality of recipes differ from each other in at least one of the processing content, processing conditions, and processing steps of the substrate W. The control device 3 controls the substrate processing device 1 in a manner that the substrate W is processed according to the recipe specified by the host computer. Each of the processes described below is executed by the control device 3 controlling the substrate processing device 1. In other words, the control device 3 is programmed in a manner that each process is executed.

[0116] Figure 6 1 is a schematic diagram showing an example of a cross section of a substrate W processed by the substrate processing apparatus 1 . Figure 7 1 and 2 are process diagrams for explaining an example of processing of a substrate W performed by the substrate processing apparatus 1 .

[0117] Figure 6 The left side of FIG. 1 shows a cross section of a substrate W before etching. Figure 6 The right side of FIG shows a cross section of the substrate W after etching. Figure 6 As shown on the right side of FIG. 9 , when the substrate W is etched, a plurality of recesses R1 recessed along the surface direction of the substrate W (a direction perpendicular to the thickness direction Dt of the substrate W) are formed on the side surface 92 s of the recessed portion 92 .

[0118] like Figure 6 As shown, the substrate W includes: a stacked film 91 formed on a mother material such as a silicon wafer; and a recessed portion 92 recessed from the outermost surface Ws of the substrate W along the thickness direction Dt of the substrate W (a direction perpendicular to the surface of the mother material of the substrate W). The stacked film 91 includes a plurality of polysilicon films P1, P2, and P3 and a plurality of silicon oxide films O1, O2, and O3.

[0119] A plurality of polysilicon films P1 to P3 and a plurality of silicon oxide films O1 to O3 are stacked in the thickness direction Dt of the substrate W in a manner that the polysilicon films and the silicon oxide films are alternately stacked. Figure 7As shown, the polysilicon films P1 to P3 are thin films formed by performing a deposition step of depositing polysilicon and a heat treatment step of heating the deposited polysilicon on a substrate W. The polysilicon films P1 to P3 may be thin films that have not been subjected to the heat treatment step.

[0120] like Figure 6 As shown, the recess 92 penetrates the plurality of polysilicon films P1 to P3 and the plurality of silicon oxide films O1 to O3 along the thickness direction Dt of the substrate W. The side surfaces of the polysilicon films P1 to P3 and the silicon oxide films O1 to O3 are exposed at the side surfaces 92s of the recess 92. The recess 92 may be any of a groove, a through hole, and a contact hole, or may be other than these.

[0121] Before the processing by the substrate processing apparatus 1 starts, a natural oxide film is formed on the surface layers of the polysilicon films P1 to P3 and the silicon oxide films O1 to O3. Figure 6 The double-dashed line on the left shows the outline of the natural oxide film. Hereinafter, a process of removing the natural oxide films of the polysilicon films P1 to P3 and the silicon oxide films O1 to O3 by supplying DHF as an example of an oxide film removing solution and then selectively etching the polysilicon films P1 to P3 by supplying an etching solution will be described.

[0122] Below, refer to Figure 1 , Figure 2 , Figure 3 ,and Figure 7 An example of processing of a substrate W performed by the substrate processing apparatus 1 is described below. In the substrate processing apparatus 1, Figure 7 The process after the start.

[0123] When the substrate W is processed by the substrate processing apparatus 1, a loading step ( Figure 7 Step S1).

[0124] Specifically, in a state where the lifting frame 32 and the blocking member 33 are located at the upper position and all the protective covers 25 are located at the lower position, the central robot CR supports the substrate W using the arm H1 and causes the arm H1 to enter the chamber 4. Then, the central robot CR places the substrate W on the arm H1 on the plurality of chuck pins 11 with the surface of the substrate W facing upward. Then, the plurality of chuck pins 11 press against the outer peripheral surface of the substrate W to hold the substrate W. After the central robot CR places the substrate W on the spin chuck 10, it causes the arm H1 to withdraw from the interior of the chamber 4.

[0125] Next, the upper gas valve 57 and the lower gas valve 21 are opened, and nitrogen begins to be ejected from the upper central opening 38 of the blocking member 33 and the lower central opening 18 of the rotating base 12. As a result, the oxygen concentration in the atmosphere in contact with the substrate W is reduced. Furthermore, the blocking member lifting unit 31 lowers the lifting frame 32 from the upper position to the lower position, and the protective cover lifting unit 27 raises any protective cover 25 from the lower position to the upper position. At this time, the rotating base 12 is maintained at a reference rotation angle at which the plurality of upper supporting parts 43 overlap with the plurality of lower supporting parts 44, respectively, when viewed from above. Therefore, the upper supporting part 43 of the blocking member 33 is supported by the lower supporting part 44 of the rotating base 12, and the blocking member 33 is separated from the lifting frame 32. Then, the rotating motor 14 is driven to start the rotation of the substrate W ( Figure 7 Step S2).

[0126] Next, a first chemical solution supplying step ( ) is performed in which DHF, which is an example of a first chemical solution, is supplied to the upper surface of the substrate W. Figure 7 Step S3).

[0127] Specifically, the first chemical liquid valve 51 is opened with the blocking member 33 in the lower position, and the center nozzle 45 starts to eject DHF. The DHF ejected from the center nozzle 45 lands on the center portion of the upper surface of the substrate W, and then flows outward along the upper surface of the substrate W that is rotating. Thus, a liquid film of DHF is formed that covers the entire upper surface of the substrate W, and DHF is supplied to the entire upper surface of the substrate W. When a predetermined time has passed since the first chemical liquid valve 51 was opened, the first chemical liquid valve 51 is closed to stop ejecting DHF.

[0128] Next, a first rinse liquid supplying step ( ) is performed in which pure water, which is an example of a rinse liquid, is supplied to the upper surface of the substrate W. Figure 7 Step S4).

[0129] Specifically, the upper rinsing liquid valve 55 is opened with the blocking member 33 in the lower position, and the central nozzle 45 starts to spray pure water. The pure water that has landed on the center of the upper surface of the substrate W flows outward along the upper surface of the rotating substrate W. The DHF on the substrate W is rinsed by the pure water sprayed from the central nozzle 45. Thus, a liquid film of pure water covering the entire upper surface of the substrate W is formed. When a predetermined time has passed since the upper rinsing liquid valve 55 was opened, the upper rinsing liquid valve 55 is closed to stop spraying pure water.

[0130] Next, a second chemical liquid supplying step ( ) is performed in which an etching liquid, which is an example of a second chemical liquid, is supplied to the upper surface of the substrate W. Figure 7 Step S5).

[0131] Specifically, the second liquid medicine valve 53 is opened with the blocking member 33 in the lower position, and the central nozzle 45 starts to spray the etching liquid. Before the etching liquid starts to be sprayed, in order to switch the protective cover 25 that receives the liquid discharged from the substrate W, the protective cover lifting unit 27 can move at least one protective cover 25 vertically. The etching liquid that lands on the central part of the upper surface of the substrate W flows outward along the upper surface of the rotating substrate W. The pure water on the substrate W is replaced by the etching liquid sprayed from the central nozzle 45. As a result, a liquid film of the etching liquid covering the entire area of ​​the upper surface of the substrate W is formed. When a predetermined time has passed since the second liquid medicine valve 53 was opened, the second liquid medicine valve 53 is closed to stop the spraying of the etching liquid.

[0132] Next, a second rinse liquid supplying step ( ) is performed in which pure water, which is an example of a rinse liquid, is supplied to the upper surface of the substrate W. Figure 7 Step S6).

[0133] Specifically, the upper rinsing liquid valve 55 is opened with the blocking member 33 in the lower position, and the central nozzle 45 starts to spray pure water. The pure water landing on the center of the upper surface of the substrate W flows outward along the upper surface of the rotating substrate W. The etching liquid on the substrate W is rinsed by the pure water sprayed from the central nozzle 45. Thus, a liquid film of pure water covering the entire upper surface of the substrate W is formed. When a predetermined time has passed since the upper rinsing liquid valve 55 was opened, the upper rinsing liquid valve 55 is closed to stop the spraying of pure water.

[0134] Next, a drying step ( Figure 7 Step S7).

[0135] Specifically, when the blocking member 33 is in the lower position, the rotating motor 14 accelerates the substrate W in the rotation direction, and rotates the substrate W at a high rotation speed (for example, several thousand rpm) that is higher than the rotation speed of the substrate W during the period from the first chemical solution supply process to the second rinse solution supply process. As a result, the liquid is removed from the substrate W, and the substrate W is dried. When a predetermined time has passed since the substrate W started to rotate at a high speed, the rotating motor 14 stops rotating. At this time, the rotating motor 14 stops the rotating base 12 at the reference rotation angle. As a result, the rotation of the substrate W stops ( Figure 7 Step S8).

[0136] Next, a step of carrying out the substrate W from the chamber 4 is performed ( Figure 7 Step S9).

[0137] Specifically, the blocking member lifting unit 31 raises the lifting frame 32 to the upper position, and the protective cover lifting unit 27 lowers all the protective covers 25 to the lower position. Then, the upper gas valve 57 and the lower gas valve 21 are closed, and the upper central opening 38 of the blocking member 33 and the lower central opening 18 of the rotating base 12 stop spraying nitrogen. Then, the central robot CR causes the arm H1 to enter the chamber 4. After the plurality of chuck pins 11 release the grip of the substrate W, the central robot CR supports the substrate W on the rotating chuck 10 with the arm H1. Then, the central robot CR supports the substrate W with the arm H1 while withdrawing the arm H1 from the interior of the chamber 4. Thus, the processed substrate W is carried out from the chamber 4.

[0138] Figure 8 It is a graph showing the relationship between the concentration of hydrogen peroxide in the etching solution and the etching speed of each crystal plane of silicon. The etching speed (etching amount per unit time) is equivalent to the etching rate.

[0139] Figure 8 The vertical axis represents the etching rate. Figure 8 The horizontal axis in represents the concentration of hydrogen peroxide. Figure 8 The circular mark, triangular mark, and square mark in represent the etching speed of Si(110) surface, Si(100) surface, and Si(111) surface, respectively. The maximum difference in the following description refers to the difference between the maximum value and the minimum value of the etching speed of Si(110) surface, Si(100) surface, and Si(111) surface. That is, the maximum difference refers to the anisotropy of the etching speed (the difference in etching speed between the plane orientations).

[0140] lie in Figure 8 The circular mark, triangular mark, and square mark on the vertical axis in the figure represent the etching rates of the Si(110) surface, Si(100) surface, and Si(111) surface when no hydrogen peroxide is added to the etching solution, that is, when the concentration of hydrogen peroxide is zero. When the concentration of hydrogen peroxide is zero, the circular mark is the largest and the square mark is the smallest. The triangular mark is located on the side of the circular mark.

[0141] When the concentration of hydrogen peroxide is concentration 1, that is, when hydrogen peroxide is added to the etching solution, the circle mark, triangle mark, and square mark are all greatly reduced compared to the case where no etching solution is added. The maximum difference when the concentration of hydrogen peroxide is concentration 1 is greatly reduced compared to the maximum difference when the concentration of hydrogen peroxide is zero. For concentration 1, the triangle mark is the largest and the square mark is the smallest. The circle mark is located near the triangle mark.

[0142] When the concentration of hydrogen peroxide is concentration 2 which is higher than concentration 1, the circle mark, triangle mark, and square mark are all lower than those of concentration 1. The maximum difference when the concentration of hydrogen peroxide is concentration 2 is smaller than the maximum difference when the concentration of hydrogen peroxide is concentration 1. With respect to concentration 2, the triangle mark is the largest and the circle mark is the smallest. The square mark is located near the middle between the triangle mark and the circle mark.

[0143] When the concentration of hydrogen peroxide is concentration 3, which is higher than concentration 2, the circular mark, the triangular mark, and the square mark have substantially the same value and overlap. Compared with concentration 2, the triangular mark and the square mark are lower, and the circular mark is slightly higher. The maximum difference when the concentration of hydrogen peroxide is concentration 3 is smaller than the maximum difference when the concentration of hydrogen peroxide is concentration 2.

[0144] according to Figure 8 The measurement results shown in FIG. 1 show that when hydrogen peroxide is added to an etching solution composed of TMAH and water, the etching rates of the Si(110) plane, the Si(100) plane, and the Si(111) plane decrease. The maximum difference in etching rate decreases as the concentration of hydrogen peroxide increases. In other words, the anisotropy of silicon decreases as the concentration of hydrogen peroxide increases. The etching rate of each crystal plane tends to decrease as the concentration of hydrogen peroxide increases.

[0145] According to the above analysis, if hydrogen peroxide is added to the etching solution formed by TMAH and water, the anisotropy of the silicon single crystal relative to the etching solution can be reduced. In addition, if the concentration of hydrogen peroxide is increased, the anisotropy of the silicon single crystal can be further reduced. However, when the concentration of hydrogen peroxide is too high, the overall etching rate of the polycrystalline silicon films P1 to P3 is reduced. Therefore, the concentration of hydrogen peroxide can be determined based on which one is prioritized, anisotropy or etching rate.

[0146] As described above, in this embodiment, an alkaline etching solution containing TMAH, hydrogen peroxide, and water is supplied to a substrate W on which polysilicon films P1 to P3 and silicon oxide films O1 to O3 are exposed. The etching solution is a liquid that etches polysilicon without etching or substantially etching silicon oxide. The etching rate of silicon oxide is lower than the etching rate of polysilicon. Therefore, the polysilicon films P1 to P3 can be selectively etched.

[0147] The etching liquid supplied to the substrate W contacts the surface of the polysilicon films P1 to P3. The surface of the polysilicon films P1 to P3 is composed of a large number of tiny silicon single crystals. The hydrogen peroxide contained in the etching liquid reacts with the surface of the large number of tiny silicon single crystals to generate silicon oxide. Therefore, if the etching liquid contains hydrogen peroxide, the etching rate of the polysilicon films P1 to P3 will decrease.

[0148] However, the hydrogen peroxide contained in the etching solution does not react uniformly with the multiple crystal faces of the silicon single crystal, but preferentially reacts with the crystal faces with high activity energy among these crystal faces. Therefore, the etching rate of the crystal faces with high activity energy is relatively greatly reduced, and the difference in etching rate between the plane orientations is reduced. As a result, the anisotropy of the silicon single crystal with respect to the etching solution is reduced. That is, the etching of the silicon single crystal constituting the polycrystalline silicon films P1 to P3 is close to isotropic.

[0149] In addition, the etching solution does not contain hydrogen fluoride compounds. Hydrogen fluoride compounds react with silicon oxide films O1 to O3 to dissolve silicon oxide films O1 to O3 in the etching solution. Silicon oxide generated by the reaction of polysilicon films P1 to P3 with hydrogen peroxide also reacts with hydrogen fluoride compounds and dissolves in the etching solution. Therefore, by excluding hydrogen fluoride compounds from the components of the etching solution, it is possible to prevent a decrease in selectivity (etching rate of polysilicon films P1 to P3 / etching rate of silicon oxide films O1 to O3), and to prevent a decrease in the effect caused by hydrogen peroxide. As a result, it is possible to uniformly etch polysilicon films P1 to P3 while suppressing the etching of silicon oxide films O1 to O3.

[0150] In this embodiment, an alkaline etching solution containing only TMAH, hydrogen peroxide, and water without any other components is supplied to the substrate W on which the polycrystalline silicon films P1 to P3 and the silicon oxide films O1 to O3 are exposed. As a result, the difference in etching rate of each plane orientation of the silicon single crystal can be reduced, and the anisotropy of the silicon single crystal constituting the polycrystalline silicon films P1 to P3 can be reduced. Therefore, the polycrystalline silicon films P1 to P3 can be uniformly etched while suppressing the etching of the silicon oxide films O1 to O3.

[0151] In this embodiment, the side surfaces of the polysilicon films P1 to P3 and the silicon oxide films O1 to O3 included in the stacked film 91 are exposed on the side surfaces 92s of the recessed portion 92 formed in the substrate W. The etching liquid is supplied into the recessed portion 92 of the substrate W. As a result, the side surfaces of the plurality of polysilicon films P1 to P3 are etched and moved in the surface direction of the substrate W (so-called side etching). That is, a plurality of notches R1 that are recessed in the surface direction of the substrate W from the side surfaces of the plurality of silicon oxide films O1 to O3 are formed in the recessed portion 92.

[0152] When the anisotropy of silicon single crystal with respect to the etching solution is high, the etching speed of the polysilicon films P1 to P3 is slightly different depending on the polysilicon films P1 to P3. In this case, the depth (distance in the surface direction of the substrate W) of the notch R1 formed in the concave portion 92 will be different depending on the notch R1. Therefore, by including hydrogen peroxide in the etching solution, the difference in etching speed between the plurality of polysilicon films P1 to P3 can be reduced, and the variation in the depth of the notch R1 can be suppressed.

[0153] In this embodiment, DHF, which is an example of an oxide film removing liquid, is supplied to the substrate W, and the natural oxide film of the polysilicon films P1 to P3 is removed from the surface layer of the polysilicon films P1 to P3. Then, an etching liquid is supplied to the substrate W to selectively etch the polysilicon films P1 to P3. The natural oxide film of the polysilicon films P1 to P3 is mainly composed of silicon oxide. The etching liquid is a liquid that etches polysilicon without etching or substantially etching silicon oxide. Therefore, by removing the natural oxide film of the polysilicon films P1 to P3 in advance, the polysilicon films P1 to P3 can be efficiently etched.

[0154] In the present embodiment, the polycrystalline silicon films P1 to P3 that have undergone a heat treatment process (in which the deposited polycrystalline silicon is heated) are etched by an alkaline etching solution containing hydrogen peroxide. If the deposited polycrystalline silicon is heated under appropriate conditions, the particle size (grain size) of the polycrystalline silicon increases. Therefore, compared with the case where the heat treatment process is not performed, the silicon single crystals constituting the polycrystalline silicon films P1 to P3 are enlarged. This means that the number of silicon single crystals exposed on the surface of the polycrystalline silicon films P1 to P3 is reduced, and the influence of anisotropy is increased. Therefore, by supplying an etching solution containing hydrogen peroxide to such polycrystalline silicon films P1 to P3, the influence of anisotropy can be effectively reduced.

[0155] In this embodiment, an etching solution with a reduced dissolved oxygen concentration is supplied to the substrate W. As described above, hydrogen peroxide reduces the anisotropy of silicon single crystals constituting the polysilicon films P1 to P3, but also reduces the etching rate of the polysilicon films P1 to P3. On the other hand, if the dissolved oxygen concentration of the etching solution is reduced, the etching rate of the polysilicon films P1 to P3 is increased. Therefore, by supplying an etching solution with a reduced dissolved oxygen concentration to the substrate W, the anisotropy of the silicon single crystal can be reduced while suppressing the reduction in the etching rate of the polysilicon films P1 to P3.

[0156] In this embodiment, the etching liquid is supplied to the substrate W in a state where the oxygen concentration in the atmosphere is low. As a result, the amount of oxygen dissolved in the etching liquid from the atmosphere is reduced, and the increase in the dissolved oxygen concentration is suppressed. As described above, hydrogen peroxide reduces the anisotropy of the silicon single crystals constituting the polysilicon films P1 to P3, but also reduces the etching rate of the polysilicon films P1 to P3. If the dissolved oxygen concentration of the etching liquid increases, the etching rate of the polysilicon films P1 to P3 is further reduced. Therefore, by reducing the oxygen concentration in the atmosphere, it is possible to suppress a further decrease in the etching rate.

[0157] In this embodiment, the concentration of hydrogen peroxide in the etching solution is changed. When hydrogen peroxide (even a very small amount) is added to the etching solution containing TMAH and water, the difference in etching rate between multiple crystal planes is reduced, and the anisotropy of the silicon single crystals constituting the polysilicon films P1 to P3 is reduced. The difference in etching rate decreases as the concentration of hydrogen peroxide increases. On the other hand, the etching rate of the polysilicon films P1 to P3 decreases as the concentration of hydrogen peroxide increases. If the reduction of anisotropy is prioritized, the concentration of hydrogen peroxide can be increased. If the etching rate is prioritized, the concentration of hydrogen peroxide can be reduced. Therefore, the etching of the polysilicon films P1 to P3 can be controlled by changing the concentration of hydrogen peroxide.

[0158] Other Implementations

[0159] The present invention is not limited to the contents of the above-described embodiment, and various modifications can be made.

[0160] For example, TMAH and the aqueous hydrogen peroxide solution may be mixed between the tank 62 and the discharge port 47 of the center nozzle 45 instead of inside the tank 62. Specifically, the oxidant pipe 78 for guiding the aqueous hydrogen peroxide solution as an example of the oxidant may be connected to the path of the chemical solution from the tank 62 to the discharge port 47 of the center nozzle 45 instead of being connected to the tank 62.

[0161] For example, you can Fig. 9 The oxidant pipe 78 may be connected to the second chemical liquid pipe 52 as shown in the figure, or the oxidant pipe 78 may be connected to the center nozzle 45. In these cases, the hydrogen peroxide solution is pumped from the tank 82 to the oxidant pipe 78 by the pump 81, and mixed with TMAH in the second chemical liquid pipe 52 or in the center nozzle 45. Thus, the alkaline etching solution containing TMAH, hydrogen peroxide and water is ejected from the ejection port 47 of the center nozzle 45.

[0162] When TMAH and the aqueous hydrogen peroxide solution are mixed, TMAH may be degraded. In such a case, if TMAH and the aqueous hydrogen peroxide solution are mixed just before the etching solution is supplied to the substrate W, the degree of degradation of TMAH can also be reduced. If TMAH and the aqueous hydrogen peroxide solution are mixed in the center nozzle 45 instead of in the second chemical liquid pipe 52, the degree of degradation of TMAH can be further reduced. On the other hand, if TMAH and the aqueous hydrogen peroxide solution are mixed in the second chemical liquid pipe 52 instead of in the center nozzle 45, a uniform etching solution can be supplied to the substrate W compared with the case where the etching solution is mixed in the center nozzle 45.

[0163] The etching liquid such as TMAH may be supplied to the lower surface of the substrate W instead of the upper surface of the substrate W. Alternatively, the etching liquid may be supplied to both the upper surface and the lower surface of the substrate W. In these cases, the lower surface nozzle 15 may be made to eject the etching liquid.

[0164] The dissolved oxygen concentration changing unit 67 may be omitted from the substrate processing apparatus 1. That is, the etching solution may be supplied to the substrate W without reducing the dissolved oxygen concentration.

[0165] In addition to or instead of supplying the aqueous hydrogen peroxide solution to the tank 62 , at least one of TMAH and water may be supplied into the tank 62 to change the concentration of hydrogen peroxide in the etching solution.

[0166] The cylindrical portion 37 may be omitted from the blocking member 33 . The upper support portion 43 and the lower support portion 44 may be omitted from the blocking member 33 and the spin chuck 10 .

[0167] The blocking member 33 may be omitted from the processing unit 2. In this case, a nozzle for spraying a processing liquid such as the first chemical liquid toward the substrate W may be provided in the processing unit 2. The nozzle may be a scanning nozzle that can move horizontally in the chamber 4, or a fixed nozzle that is fixed relative to the partition wall 6 of the chamber 4. The nozzle may also include a plurality of liquid spray ports that simultaneously spray the processing liquid toward a plurality of positions spaced apart in the radial direction of the substrate W, thereby supplying the processing liquid to the upper surface or the lower surface of the substrate W. In this case, at least one of the flow rate, temperature, and concentration of the sprayed processing liquid may be changed for each liquid spray port.

[0168] The number of polysilicon films included in the stacked film 91 may be 1. Similarly, the number of silicon oxide films included in the stacked film 91 may be 1.

[0169] When a silicon oxide film is formed on the polysilicon film, the recess 92 may penetrate only the silicon oxide film in the thickness direction Dt of the substrate W. That is, the surface of the polysilicon film may be the bottom surface of the recess 92. In this case, a plurality of recesses 92 may be provided on the substrate W.

[0170] The substrate processing apparatus 1 is not limited to an apparatus that processes a disc-shaped substrate W, and may be an apparatus that processes a polygonal substrate W.

[0171] The substrate processing apparatus 1 may be a batch type apparatus that processes a plurality of substrates W at a time.

[0172] Two or more of all the aforementioned configurations may be combined. Two or more of all the aforementioned steps may be combined.

[0173] This application corresponds to Japanese Patent Application No. 2018-038993 filed with the Japan Patent Office on March 5, 2018, and all disclosed contents of the application are incorporated herein by reference.

[0174] Although the embodiments of the present invention have been described in detail, they are merely specific examples used to clarify the technical content of the present invention, and the present invention should not be limited to these specific examples. The spirit and scope of the present invention are limited only by the attached claims.

[0175] Description of Reference Numerals

[0176] 1: Substrate processing device

[0177] 3: Control device

[0178] 10: Rotary chuck (substrate holding unit)

[0179] 15: Lower surface nozzle (etching liquid supply unit)

[0180] 21: Lower gas valve (atmospheric oxygen concentration change unit)

[0181] 22: Lower gas flow control valve (atmospheric oxygen concentration change unit)

[0182] 45: Center nozzle

[0183] 46: First chemical liquid discharge port (oxide film removal liquid supply unit)

[0184] 47: Second liquid discharge port (etching liquid supply unit)

[0185] 57: Upper gas valve (atmospheric oxygen concentration change unit)

[0186] 58: Upper gas flow control valve (atmospheric oxygen concentration change unit)

[0187] 61: Chemical solution preparation unit (etching solution preparation unit)

[0188] 67: Dissolved oxygen concentration changing unit (dissolved oxygen concentration changing unit)

[0189] 77: Oxidant concentration changing unit (Oxidant concentration changing unit)

[0190] 79: Oxidant valve (oxidant concentration changing unit)

[0191] 80: Oxidant flow control valve (oxidant concentration changing unit)

[0192] 91: Laminated film

[0193] 92: Concave

[0194] 92s: Side of the concave part

[0195] Dt: thickness direction of substrate

[0196] O1, O2, O3: Silicon oxide film

[0197] P1, P2, P3: Polysilicon film

[0198] W: substrate

[0199] Ws: Outermost surface

Claims

1. A substrate processing method, comprising the following steps: an etching solution preparation step, wherein an organic base, an oxidant and water are mixed to prepare an alkaline etching solution containing an organic base, an oxidant and water but not containing a hydrogen fluoride compound; A selective etching step of supplying the etching solution to the substrate from which the polysilicon film and the silicon oxide film are exposed before the etching solution prepared in the etching solution preparation step is supplied, and etching the polysilicon film while suppressing etching of the silicon oxide film; and In the natural oxide film removing step, an oxide film removing solution is supplied to the substrate before the selective etching step to remove the natural oxide films of the polysilicon film and the silicon oxide film, thereby exposing the polysilicon film and the silicon oxide film.

2. The substrate processing method according to claim 1, wherein: The etching solution preparation step is a step of preparing an alkaline liquid formed of the organic base, the oxidant, and the water.

3. The substrate processing method according to claim 1 or 2, wherein: The substrate comprises: a stacked film including a plurality of the polysilicon films and a plurality of the silicon oxide films stacked in a thickness direction of the substrate in such a manner that the polysilicon films and the silicon oxide films are alternately stacked; and a recessed portion that is recessed from the outermost surface of the substrate in the thickness direction of the substrate and penetrates the plurality of polysilicon films and the plurality of silicon oxide films, The selective etching step includes a step of supplying the etching solution at least into the recessed portion.

4. The substrate processing method according to claim 1 or 2, wherein: The polysilicon film is a thin film obtained by performing a plurality of steps including: a deposition step of depositing polysilicon; and a heat treatment step of heating the polysilicon deposited in the deposition step.

5. The substrate processing method according to claim 1 or 2, wherein: The etching solution preparation step includes a dissolved oxygen concentration changing step of reducing the dissolved oxygen concentration of the etching solution. 6 . The substrate processing method according to claim 1 , further comprising an atmospheric oxygen concentration changing step of reducing an oxygen concentration in an atmosphere in contact with the etching solution held on the substrate.

7. The substrate processing method according to claim 1 or 2, wherein: The etching solution preparation step includes an oxidant concentration changing step of changing the concentration of the oxidant in the etching solution.

8. The substrate processing method according to claim 1 or 2, wherein: From the start of supplying the oxide film removing liquid until the supplying of the etching liquid, the polysilicon film and the silicon oxide film are maintained in a state of being in contact with the liquid.

9. The substrate processing method according to claim 1 or 2, wherein: In the etching solution preparation process, the concentration of the oxidant in the etching solution is determined based on which of the reduction in the anisotropy of the etching of the polysilicon film relative to the etching solution and the etching speed of the polysilicon film is prioritized, thereby preparing the etching solution with the determined concentration of the oxidant.

10. A substrate processing apparatus comprising: a substrate holding unit that holds the substrate with the polysilicon film and the silicon oxide film exposed; An etching solution preparation unit, which prepares an alkaline etching solution containing an organic base, an oxidant and water but not containing a hydrogen fluoride compound by mixing an organic base, an oxidant and water; an etching liquid supply unit that supplies the etching liquid prepared by the etching liquid preparation unit to the substrate held by the substrate holding unit and from which the polysilicon film and the silicon oxide film are exposed since before the etching liquid is supplied; an oxide film removing liquid supply unit that supplies the oxide film removing liquid to the substrate held by the substrate holding unit; and A control device controls the etching solution preparation unit, the etching solution supply unit and the oxide film removal solution supply unit, The control device performs the following steps: An etching solution preparation step, wherein the etching solution preparation unit prepares the etching solution; In a selective etching step, the etching liquid supply unit supplies the etching liquid to the substrate to etch the polysilicon film while suppressing etching of the silicon oxide film; and Natural oxide film removal process: before the selective etching process, the oxide film removal liquid supply unit supplies the oxide film removal liquid to the substrate, thereby removing the natural oxide films of the polysilicon film and the silicon oxide film, thereby exposing the polysilicon film and the silicon oxide film.

11. The substrate processing apparatus according to claim 10, wherein: The etching solution preparation unit is a unit for preparing an alkaline liquid formed by the organic base, the oxidant and the water.

12. The substrate processing apparatus according to claim 10 or 11, wherein: The substrate comprises: a stacked film including a plurality of the polysilicon films and a plurality of the silicon oxide films stacked in a thickness direction of the substrate in such a manner that the polysilicon films and the silicon oxide films are alternately stacked; and a recessed portion that is recessed from the outermost surface of the substrate in the thickness direction of the substrate and penetrates the plurality of polysilicon films and the plurality of silicon oxide films, The etching liquid supply unit includes a unit that supplies the etching liquid at least into the recessed portion.

13. The substrate processing apparatus according to claim 10 or 11, wherein: The polysilicon film is a thin film obtained by performing a plurality of steps including: a deposition step of depositing polysilicon; and a heat treatment step of heating the polysilicon deposited in the deposition step.

14. The substrate processing apparatus according to claim 10 or 11, wherein: The etching solution preparation unit includes a dissolved oxygen concentration changing unit that reduces the dissolved oxygen concentration of the etching solution. 15 . The substrate processing apparatus according to claim 10 , further comprising an atmospheric oxygen concentration changing unit for reducing an oxygen concentration in an atmosphere in contact with the etching solution held on the substrate.

16. The substrate processing apparatus according to claim 10 or 11, wherein: The etching solution preparation unit includes an oxidant concentration changing unit that changes the concentration of the oxidant in the etching solution.

17. The substrate processing apparatus according to claim 10 or 11, wherein: From the start of supplying the oxide film removing liquid until the supplying of the etching liquid, the polysilicon film and the silicon oxide film are maintained in a state of being in contact with the liquid.

18. The substrate processing apparatus according to claim 10 or 11, wherein: In the etching solution preparation process, the concentration of the oxidant in the etching solution is determined based on which of the reduction in the anisotropy of the etching of the polysilicon film relative to the etching solution and the etching speed of the polysilicon film is prioritized, thereby preparing the etching solution with the determined concentration of the oxidant.

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