Substrate processing method and substrate processing apparatus

Abstract

A recess 95 is formed on the substrate W. The width of the recess 95 is shorter than its depth. At least a portion of the upper part and at least a portion of the lower part of the side surface 95s exposes an object to be etched, representing at least one of monocrystalline silicon, polycrystalline silicon, and amorphous silicon. The object to be etched is etched by supplying a first alkaline etchant containing dissolved inert gases to the substrate W. The object to be etched is further etched by supplying a second alkaline etchant containing dissolved gases and having a higher dissolved oxygen concentration than the first etchant to the substrate W before or after the first etchant is supplied to the substrate W.

Description

Technical Field

[0001] This invention claims priority to Japanese Patent Application No. 2020-146098, filed on August 31, 2020, the entire contents of which are incorporated herein by reference.

[0002] This invention relates to a substrate processing method and a substrate processing apparatus for processing substrates. The substrate includes, for example, substrates for FPD (flat panel display) devices such as semiconductor wafers, liquid crystal display devices, and organic EL (electroluminescence) display devices; substrates for optical discs; substrates for magnetic disks; substrates for optical discs; substrates for photomasks; ceramic substrates; and substrates for solar cells. Background Technology

[0003] In the manufacturing processes of semiconductor devices and FPDs, there are instances where alkaline etching solutions such as TMAH (tetramethyl ammonium hydroxide) and KOH (potassium hydroxide) are supplied to substrates such as semiconductor wafers and glass substrates for FPDs. Patent Document 1 discloses a method of etching a polysilicon film formed on a substrate by supplying TMAH to the substrate. Patent Document 1 also describes how the dissolved oxygen concentration of TMAH is adjusted to an optimal level by dissolving nitrogen or dry air into the TMAH.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-19089 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] Although Patent Document 1 discloses etching the polysilicon film formed on the outermost layer of a substrate by supplying TMAH, it does not disclose whether a pattern is formed on the outermost layer of the substrate. Furthermore, although Patent Document 1 discloses supplying TMAH to multiple substrates while changing the dissolved oxygen concentration of TMAH, it does not disclose supplying TMAH with different dissolved oxygen concentrations to the same substrate.

[0009] In the manufacturing process of semiconductor devices, there are cases where an alkaline etchant such as TMAH is supplied to the surface of a substrate with a pattern such as recesses to etch the side surfaces of the recesses. In this case, there is a need for uneven etching of the side surfaces of the recesses, and the side surfaces of the recesses are intentionally etched unevenly. This need usually includes suppressing an increase in processing time. Patent Document 1 does not disclose a method or apparatus for addressing this need, nor does it provide any guidance.

[0010] Therefore, one of the objectives of this invention is to provide a substrate processing method and a substrate processing apparatus that can suppress the increase in processing time and intentionally and unevenly etch the sides of the recesses formed on the substrate.

[0011] means for solving problems

[0012] An embodiment of the present invention provides a substrate processing method for processing a substrate having a recess, the width of which is shorter than its depth, exposing an etchable object representing at least one of monocrystalline silicon, polycrystalline silicon, and amorphous silicon at least a portion of the upper part and at least a portion of the lower part of the side surface of the recess. The substrate processing method includes: a first etching step, in which the etchable object exposed on the side surface of the recess is etched by supplying the substrate with an alkaline first etching solution containing dissolved inert gas; and a second etching step, in which the etchable object exposed on the side surface of the recess is etched by supplying the substrate with an alkaline second etching solution containing dissolved gas and having a dissolved oxygen concentration higher than that of the first etching solution.

[0013] In this method, a first alkaline etchant solution containing dissolved inert gas is supplied to the substrate. This etches the side surfaces of the recesses formed on the substrate. Similarly, a second alkaline etchant solution containing dissolved gas is supplied to the substrate. This etches the side surfaces of the recesses. Therefore, the side surfaces of the recesses are etched in stages through the supply of the first and second etchant solutions.

[0014] The etched object, representing at least one of monocrystalline silicon, polycrystalline silicon, and amorphous silicon, has at least a portion of the upper part of the side surface of the recess and at least a portion of the lower part of the side surface of the recess exposed. When a liquid with a high dissolved oxygen concentration is supplied to the etched object, the surface layer of the etched object changes to silicon oxide. Silicon oxide is not etched by alkaline etchants or is hardly etched by alkaline etchants.

[0015] Dissolved oxygen present in the first etching solution is removed from the first etching solution through the dissolution of inactive gases. Because the dissolved oxygen concentration in the first etching solution is low, the object to be etched will not be oxidized or will hardly be oxidized even when the first etching solution comes into contact with it. Therefore, by supplying the first etching solution to the substrate, the object exposed on the side of the recess can be etched uniformly at a high etching rate.

[0016] On the other hand, since the dissolved oxygen concentration of the second etching solution is higher than that of the first etching solution, when the second etching solution comes into contact with the object to be etched, the surface of the object is oxidized, thus transforming into silicon oxide, which is difficult to be corroded by the second etching solution. However, the entire surface area of ​​the object to be etched is not uniformly oxidized but unevenly oxidized.

[0017] That is, due to the narrow width of the recess, when the second etchant is supplied to the recess, the dissolved oxygen contained in the second etchant comes into contact with the object to be etched near the entrance of the recess, thereby oxidizing the object. Therefore, although only slightly, the second etchant with a reduced dissolved oxygen concentration flows to the bottom of the recess. Even at a point slightly separated from the entrance of the recess, the dissolved oxygen in the second etchant comes into contact with the object to be etched and is consumed. This phenomenon repeats continuously, resulting in the dissolved oxygen concentration of the second etchant decreasing as it approaches the bottom of the recess.

[0018] If the objects within the recesses are at the same depth, they are uniformly etched by the second etching solution. However, the amount of etching occurs as the object approaches the bottom of the recess. That is, because the surface layer of the object near the entrance of the recess changes to silicon oxide, it is difficult for the object to be etched by the second etching solution. On the other hand, because the surface layer of the object near the bottom of the recess does not change to silicon oxide or hardly changes to silicon oxide, it is etched by the second etching solution. Therefore, the amount of etching occurs near the bottom of the recess more than near the entrance of the recess.

[0019] Thus, by supplying the first etchant to the substrate, the object to be etched exposed on the side of the recess can be uniformly etched at a high etching rate. Furthermore, by supplying the second etchant to the substrate, the object to be etched can be etched in a manner where the etching amount increases in stages or continuously as the bottom of the recess approaches. Therefore, by supplying the first and second etchants to the substrate separately, it is possible to suppress the increase in processing time and to intentionally etch the side of the recess unevenly.

[0020] The recess formed in the substrate can be a hole or a groove. That is, the side surface of the recess can be a continuous cylindrical surface covering the entire circumference, or it can be one or both of a pair of parallel side surfaces facing each other. The recess can also be recessed in the thickness direction of the substrate, or it can be recessed in the direction of a surface of the substrate orthogonal to the thickness direction of the substrate. In the former case, the recess can be recessed from the outermost surface of the substrate towards the thickness direction of the substrate, or it can be recessed from other planes towards the thickness direction of the substrate.

[0021] The first etching solution is an alkaline etching solution that forcibly dissolves inactive gases, and the second etching solution is an alkaline etching solution that forcibly dissolves dissolved gases. As long as the dissolved oxygen concentration of the second etching solution is higher than that of the first etching solution, the dissolved gas can be an inactive gas such as nitrogen or argon, or an oxygen-containing gas.

[0022] In the described embodiment, at least one of the following features may also be added to the substrate processing method.

[0023] The second etching process is as follows: after supplying the first etching solution to the substrate, the second etching solution is supplied to the substrate.

[0024] In this method, a first etchant with a low dissolved oxygen concentration is supplied to the substrate, followed by a second etchant with a relatively high dissolved oxygen concentration. When the second etchant is supplied to the substrate first, the object to be etched exposed on the side of the recess is oxidized. Therefore, when the first etchant is supplied, the object to be etched is etched unevenly, and the etching rate is reduced. By supplying the first etchant first, compared to supplying the second etchant first, the processing time can be shortened, and the actual shape of the etched object can be made closer to the desired shape.

[0025] The second etching process includes the following steps: supplying the second etching solution to the substrate, thereby replacing the first etching solution in contact with the substrate with the second etching solution.

[0026] In this method, after the first etchant is supplied to the substrate, a second etchant is supplied to the substrate instead of a liquid other than the second etchant. This replaces the first etchant that is in contact with the substrate with the second etchant. If a liquid other than the second etchant is supplied to the substrate before the second etchant is supplied, the object to be etched exposed on the side of the recess may be oxidized into an undesirable shape. By replacing the first etchant that is in contact with the substrate with the second etchant, such oxidation can be suppressed or prevented, thereby enabling high-precision etching of the object.

[0027] The width of the recess before being supplied with the first etchant and the second etchant decreases as it approaches the bottom of the recess; the second etching process is as follows: the side surface of the recess is etched in such a way that the amount of etching on the side surface of the recess increases as it approaches the bottom of the recess.

[0028] In this method, the recess, which tapers as it approaches the bottom, is etched using a first etching solution and a second etching solution. During the supply of the first etching solution, the object exposed on the side of the recess is etched uniformly; during the supply of the second etching solution, the amount of etching increases as the object approaches the bottom of the recess. After supplying the first and second etching solutions, the width of the recess becomes uniform from the entrance to the bottom, or any unevenness in the width of the recess is reduced. Therefore, even if the width of the recess is uneven before etching, the shape of the recess can be adjusted.

[0029] At least one of the first etching solution and the second etching solution is an alkaline etching solution comprising a compound for preventing hydroxide ions from contacting the object being etched.

[0030] Polycrystalline silicon is composed of multiple monocrystalline silicon units. When polycrystalline silicon is etched with an alkaline etchant that does not contain compounds, very fine unevenness is formed on the surface of the polycrystalline silicon. This is because the (110), (100), and (111) planes of silicon are exposed on the surface of the polycrystalline silicon, and the etching rates of the (110), (100), and (111) planes of silicon are different from each other. When monocrystalline silicon is etched, very fine unevenness is formed on the surface of the monocrystalline silicon for the same reason.

[0031] Hydroxide ions (OH-) in alkaline etching solutions - The compound reacts with silicon (Si) to etch polycrystalline silicon and other etchable objects. When the compound is added to an alkaline etching solution, it hinders the contact between hydroxide ions and silicon, reducing the etching rate of the (110), (100), and (111) planes of silicon. However, the etching rate does not decrease uniformly across the multiple crystal planes; rather, the etching rate decreases significantly on the crystal planes with high etching rates. Consequently, the difference in etching rates across the multiple crystal planes decreases.

[0032] Thus, by adding compounds to the alkaline etchant, the anisotropy of the etchant for etched objects such as polycrystalline silicon is reduced. That is, the etching of the object approaches isotropic etching, with a uniform etching amount regardless of the location. This mitigates the planar orientation dependence of the etching rate. Therefore, the formation of the aforementioned unevenness can be suppressed or prevented, thereby achieving a flattened surface on the etched object.

[0033] The concentration of the compound in the alkaline etching solution is set according to the required etching uniformity and the required etching rate.

[0034] The first etching process includes a first etching solution preparation process of preparing the first etching solution by diluting the stock solution of the alkaline etching solution with at least one of a first diluent and a second diluent with different dissolved oxygen concentrations. The second etching process includes a second etching solution preparation process of preparing the second etching solution by diluting the stock solution with at least one of the first diluent and the second diluent.

[0035] According to this method, a first etching solution and a second etching solution can be prepared by diluting the stock solution of an alkaline etching solution with at least one of a first diluent and a second diluent. The first diluent and the second diluent are liquids with different dissolved oxygen concentrations. Therefore, by making the proportions of the first diluent and the second diluent in the first etching solution different from the proportions of the first diluent and the second diluent in the second etching solution, the dissolved oxygen concentrations of the first etching solution and the second etching solution can be adjusted.

[0036] In the substrate processing method, multiple substrates are processed one by one.

[0037] In the substrate processing method, multiple substrates are processed together.

[0038] Another embodiment of the present invention provides a substrate processing apparatus for processing a substrate having recesses, the width of which is shorter than its depth, exposing an etchable object representing at least one of monocrystalline silicon, polycrystalline silicon, and amorphous silicon at least a portion of the upper part and at least a portion of the lower part of the side surface of the recess. The substrate processing apparatus includes: a first etching unit for etching the etchable object exposed on the side surface of the recess by supplying an alkaline first etching solution containing dissolved inert gases to the substrate; and a second etching unit for etching the etchable object exposed on the side surface of the recess by supplying a second alkaline etching solution containing dissolved gases and having a dissolved oxygen concentration higher than that of the first etching solution to the substrate. According to this structure, the same effect as the substrate processing method described above can be achieved.

[0039] The above-mentioned objects, other objects, features, and effects of the present invention will become more apparent from the accompanying drawings and from the following description of embodiments of the invention. Attached Figure Description

[0040] Figure 1A This is a schematic diagram of the substrate processing apparatus according to the first embodiment of the present invention, viewed from above.

[0041] Figure 1BThis is a schematic diagram of the substrate processing device viewed from the side.

[0042] Figure 2 This is a schematic diagram showing the interior of the processing unit of the substrate processing device viewed horizontally.

[0043] Figure 3 It is Figure 2 An enlarged image of a portion of the image.

[0044] Figure 4 This is an example graph showing the relationship between the etching rate of the three crystal faces of silicon and the concentration of propylene glycol in the etching solution.

[0045] Figure 5A This diagram illustrates the mechanism by which the contact between hydroxide ions and polycrystalline silicon is supposedly hindered by a barrier substance.

[0046] Figure 5B This diagram illustrates the mechanism by which the contact between hydroxide ions and polycrystalline silicon is supposedly hindered by a barrier substance.

[0047] Figure 6 This is a schematic diagram of a processing liquid supply unit of a substrate processing apparatus that supplies processing liquids such as etching solution to a substrate.

[0048] Figure 7 This is a block diagram showing the electrical structure of the substrate processing device.

[0049] Figure 8 This is a process diagram illustrating an example of substrate processing performed by a substrate processing apparatus.

[0050] Figure 9A , Figure 9B as well as Figure 9C This is a schematic diagram showing an example of a cross-section of a substrate.

[0051] Figure 10A This is a schematic diagram showing another example of a cross-section of a substrate.

[0052] Figure 10B This is a schematic diagram showing another example of a cross-section of a substrate.

[0053] Figure 10C This is a schematic diagram showing another example of a cross-section of a substrate.

[0054] Figure 11 This is a schematic diagram showing the etching unit included in the substrate processing apparatus according to the second embodiment of the present invention. Detailed Implementation

[0055] Figure 1AThis is a schematic diagram of the substrate processing apparatus 1 according to the first embodiment of the present invention, viewed from above. Figure 1B This is a schematic diagram of the substrate processing apparatus 1 viewed from the side.

[0056] like Figure 1A As shown, the substrate processing apparatus 1 is a single-sheet type apparatus for processing wafer-shaped substrates W, such as semiconductor wafers, one by one. The substrate processing apparatus 1 includes: a load port LP for holding a container C for accommodating the substrate W; multiple processing units 2 for processing the substrate W transported from the container C on the load port LP; a transport robot for transporting the substrate W between the container C on the load port LP and the processing units 2; and a control device 3 for controlling the substrate processing apparatus 1.

[0057] The handling robots include: an indexer robot IR, which moves substrate W into and out of a container C on a loading port LP; and a center robot CR, which moves substrate W into and out of multiple processing units 2. The indexer robot IR moves substrate W between the loading port LP and the center robot CR, and the center robot CR moves substrate W between the indexer robot IR and the processing units 2. The center robot CR includes a hand H1 for supporting substrate W, and the indexer robot IR includes a hand H2 for supporting substrate W.

[0058] Multiple processing units 2 are formed in multiple towers TW arranged around the central robot arm CR when viewed from above. Figure 1A An example of four tower TWs is shown. The central robot CR can also access any one of the tower TWs. Figure 1B As shown, each tower TW includes multiple (e.g., three) processing units 2 stacked vertically.

[0059] Figure 2 This is a schematic diagram showing the interior of the processing unit 2 of the substrate processing apparatus 1 viewed horizontally. Figure 3 It is Figure 2 An enlarged image of a portion of the image. Figure 2 The image shows the lifting frame 32 and the blocking member 33 in the lower position. Figure 3 The image shows the lifting frame 32 and the blocking member 33 in the upper position. In the following description, unless otherwise specified, TMAH refers to an aqueous solution of TMAH.

[0060] The processing unit 2 includes: a box-shaped chamber 4 having an internal space; a rotating chuck 10 that keeps a substrate W horizontal while rotating the substrate W about a vertical rotation axis A1 passing through the center of the substrate W within the chamber 4; and a cylindrical processing cup 23 that surrounds the rotating chuck 10 about the rotation axis A1.

[0061] The chamber 4 includes: a box-shaped partition 6 with an inlet / outlet 6b for the substrate W to pass through; and a shutter 7 for opening and closing the inlet / outlet 6b. The chamber 4 also includes a rectifier plate 8, which is positioned below an air outlet 6a that opens onto the top surface of the partition 6. An FFU (fan filter unit) 5 for supplying clean air (air filtered by a filter) is positioned above the air outlet 6a. An exhaust duct 9 for discharging gas from the chamber 4 is connected to the processing cup 23. The air outlet 6a is located at the upper end of the chamber 4, and the exhaust duct 9 is located at the lower end of the chamber 4. A portion of the exhaust duct 9 extends outside the chamber 4.

[0062] The rectifier plate 8 divides the internal space of the partition wall 6 into an upper space Su above the rectifier plate 8 and a lower space SL below the rectifier plate 8. The upper space Su between the top surface of the partition wall 6 and the upper surface of the rectifier plate 8 is a diffusion space for clean air diffusion. The lower space SL between the lower surface of the rectifier plate 8 and the bottom surface of the partition wall 6 is a processing space for processing the substrate W. The rotary chuck 10 and the processing cup 23 are disposed in the lower space SL. The vertical distance from the bottom surface of the partition wall 6 to the lower surface of the rectifier plate 8 is longer than the vertical distance from the upper surface of the rectifier plate 8 to the top surface of the partition wall 6.

[0063] FFU5 delivers clean air to the upper space Su via air outlet 6a. The clean air supplied to the upper space Su collides with the rectifier plate 8 and diffuses within the upper space Su. The clean air in the upper space Su flows downward from the entire rectifier plate 8 through multiple through holes running vertically through it. Clean air supplied to the lower space SL is drawn into the processing cup 23 and discharged from the lower end of the chamber 4 through the exhaust duct 9. Thus, a uniform downflow of clean air flowing downward from the rectifier plate 8 is formed in the lower space SL. The processing of the substrate W is performed under the condition of the formed downflow of clean air.

[0064] The rotary chuck 10 includes: a circular spin base 12 held in a horizontal position; a plurality of chuck pins 11 holding the substrate W in a horizontal position above the spin base 12; a rotation shaft 13 extending downward from the center of the spin base 12; and a spin motor 14 that rotates the spin base 12 and the plurality of chuck pins 11 by rotating the rotation shaft 13. The rotary chuck 10 is not limited to a clamping chuck in which the plurality of chuck pins 11 contact the outer peripheral surface of the substrate W, but can also be a vacuum chuck that holds the substrate W horizontally by adsorbing the back side (lower surface) of the substrate W, which is a non-component forming surface, onto the upper surface 12u of the spin base 12.

[0065] 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 opposing surface to the lower surface of the substrate W. The upper surface 12u of the rotating base 12 is annular around 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. A chuck pin 11 protrudes upward from the outer periphery of the upper surface 12u of the rotating base 12. The chuck pin 11 is held by the rotating base 12. The substrate W is held by a plurality of chuck pins 11 when the lower surface of the substrate W is separated from the upper surface 12u of the rotating base 12.

[0066] The processing unit 2 includes a lower surface nozzle 15, which sprays processing liquid toward the center of the lower surface of the substrate W. The lower surface nozzle 15 includes: a nozzle circular plate portion disposed between the upper surface 12u of the rotating base 12 and the lower surface of the substrate W; and a nozzle cylindrical portion extending downward from the nozzle circular plate portion. The liquid outlet 15p of the lower surface nozzle 15 opens at the center of the upper surface of the nozzle circular plate portion. When the substrate W is held by the rotating chuck 10, the liquid outlet 15p of the lower surface nozzle 15 is vertically aligned with the center of the lower surface of the substrate W.

[0067] The substrate processing apparatus 1 includes: a lower rinsing fluid piping 16 for guiding rinsing fluid to a lower surface nozzle 15; and a lower rinsing fluid valve 17 installed on the rinsing fluid piping 16. When the lower rinsing fluid valve 17 is opened, the rinsing fluid guided by the lower rinsing fluid piping 16 is sprayed upward from the lower surface nozzle 15 and supplied to the center of the lower surface of the substrate W. The rinsing fluid supplied to the lower surface nozzle 15 is pure water (DIW). The rinsing fluid supplied to the lower surface nozzle 15 is not limited to pure water, and may also be any one of IPA (isopropyl alcohol), carbonated water, electrolyzed ionized water, hydrogen water, ozone water, and hydrochloric acid water with a dilution concentration (e.g., about 1 ppm to 100 ppm).

[0068] Although not shown, the downflushing valve 17 includes: a valve body with an internal flow path for fluid flow and an annular valve seat surrounding the internal flow path; a valve body movable relative to the valve seat; and an actuator that moves the valve body between a closed position where the valve body is in contact with the valve seat and an open position where the valve body is separated from the valve seat. The same applies to other valves. The actuator can be a pneumatic actuator, an electric actuator, or an actuator other than these. The control device 3 controls the actuator to open and close the downflushing valve 17.

[0069] The outer peripheral surface of the lower surface nozzle 15 and the inner peripheral surface of the rotating base 12 form a lower cylindrical passage 19 extending vertically. The lower cylindrical passage 19 includes a lower central opening 18 that opens at the center of the upper surface 12u of the rotating base 12. The lower central opening 18 is disposed below the nozzle circular plate portion of the lower surface nozzle 15. The substrate processing apparatus 1 includes: a lower gas pipe 20 for guiding inactive gas supplied to the lower central opening 18 via the lower cylindrical passage 19; a lower gas valve 21 installed on the lower gas pipe 20; and a lower gas flow rate regulating valve 22 for changing the flow rate of the inactive gas supplied from the lower gas pipe 20 to the lower cylindrical passage 19.

[0070] 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; it can also be other inert gases such as helium or argon. These inert gases are low-oxygen gases with an oxygen concentration lower than that in air (approximately 21 vol%).

[0071] When the lower gas valve 21 is opened, 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 regulating valve 22. Subsequently, the nitrogen gas flows radially in all directions within the space between the lower surface of the substrate W and the upper surface 12u of the rotating base 12. Therefore, the space between the substrate W and the rotating base 12 is filled with nitrogen gas, thereby reducing the oxygen concentration in the ambient gas. The oxygen concentration in the space between the substrate W and the rotating base 12 changes according to the opening of the lower gas valve 21 and the lower gas flow regulating valve 22. The lower gas valve 21 and the lower gas flow regulating valve 22 are included in an ambient gas oxygen concentration changing unit, which is used to change the oxygen concentration in the ambient gas in contact with the substrate W.

[0072] The processing cup 23 includes: a plurality of guards 25 for receiving liquid discharged from the substrate W to the outside; a plurality of cups 26 for receiving liquid guided downward through the plurality of guards 25; and a cylindrical outer wall member 24 surrounding the plurality of guards 25 and the plurality of cups 26. Figure 2 An example is shown with two protective covers 25 and two cups 26.

[0073] The protective cover 25 includes: a cylindrical protective cover portion 25b surrounding the rotating chuck 10; and an annular protective cover top 25a extending obliquely upward from the upper end of the protective cover portion 25b toward the rotation axis A1. Multiple protective cover tops 25a overlap vertically, and multiple protective cover portions 25b are arranged concentrically. Multiple cups 26 are respectively disposed below the multiple protective cover portions 25b. Each cup 26 forms an annular liquid receiving tank that opens upwards.

[0074] Processing unit 2 includes a protective cover lifting unit 27, which allows multiple protective covers 25 to be raised and lowered individually. The protective cover lifting unit 27 positions the protective covers 25 at any position, from an upper position to a lower position. The upper position is a position where the upper end 25u of the protective cover 25 is positioned above the holding position of the substrate W, which is held by the rotating chuck 10. The lower position is a position where the upper end 25u of the protective cover 25 is positioned below the holding position. The annular upper end of the protective cover top 25a corresponds to the upper end 25u of the protective cover 25. When viewed from above, the upper end 25u of the protective cover 25 surrounds the substrate W and the rotating base 12.

[0075] When the processing liquid is supplied to the substrate W while the substrate W is rotated by the rotary chuck 10, the processing liquid supplied to the substrate W is thrown off the substrate W. During the supply of processing liquid to the substrate W, the upper end 25u of at least one protective cover 25 is positioned higher than the substrate W. Therefore, the processing liquid, such as medicine or rinsing solution, discharged from the substrate W is caught by one of the protective covers 25 and guided to the cup 26 corresponding to that protective cover 25.

[0076] like Figure 3 As shown, the processing unit 2 includes: a lifting frame 32 disposed above the rotary chuck 10; a blocking member 33 suspended from the lifting frame 32; a central nozzle 45 inserted into the blocking member 33; and a blocking member lifting unit 31, which raises and lowers the blocking member 33 and the central nozzle 45 by raising and lowering the lifting frame 32. The lifting frame 32, the blocking member 33, and the central nozzle 45 are disposed below the rectifier plate 8.

[0077] The blocking member 33 includes: a circular plate portion 36 disposed above the rotary chuck 10; and a cylindrical portion 37 extending downward from the outer periphery of the circular plate portion 36. The blocking member 33 includes an upwardly recessed cup-shaped inner surface. The inner surface of the blocking member 33 includes the lower surface 36L of the circular plate portion 36 and the inner peripheral surface 37i of the cylindrical portion 37. Hereinafter, the lower surface 36L of the circular plate portion 36 will be referred to as the lower surface 36L of the blocking member 33.

[0078] 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 peripheral surface 37i of the cylindrical portion 37 extends downward from the outer periphery 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 peripheral surface 37i of the cylindrical portion 37. The inner diameter at the lower end of the inner peripheral surface 37i of the cylindrical portion 37 is larger than the diameter of the substrate W. The inner diameter at the lower end of the inner peripheral surface 37i of the cylindrical portion 37 may also be larger than the outer diameter of the rotating base 12. The blocking member 33 is positioned in the lower position described later. Figure 2 When the substrate W is in the position shown, it is surrounded by the inner peripheral surface 37i of the cylindrical portion 37.

[0079] The lower surface 36L of the circular plate portion 36 is annular, surrounding the rotation axis A1. An upper central opening 38 is formed at the center of the lower surface 36L of the circular plate portion 36, with its inner periphery forming an opening at the center of the lower surface 36L. A through hole extending upward from the upper central opening 38 is formed on the inner peripheral surface of the blocking member 33. The through hole of the blocking member 33 extends vertically through the blocking member 33. A central nozzle 45 is inserted into the through hole of the blocking member 33. The outer diameter of the lower end of the central nozzle 45 is smaller than the diameter of the upper central opening 38.

[0080] The inner circumferential surface of the blocking member 33 is coaxial with the outer circumferential surface of the central nozzle 45. The inner circumferential surface of the blocking member 33 surrounds the outer circumferential surface of the central nozzle 45 at intervals in the radial direction (orthogonal to the rotation axis A1). The inner circumferential surface of the blocking member 33 and the outer circumferential surface of the central nozzle 45 form an upper cylindrical passage 39 extending vertically. The central nozzle 45 protrudes upward from the lifting frame 32 and the blocking member 33. When the blocking member 33 is suspended from the lifting frame 32, the lower end of the central nozzle 45 is positioned higher than the lower surface 36L of the circular plate portion 36. Treatment liquids such as medicine or rinsing liquid are sprayed downward from the lower end of the central nozzle 45.

[0081] 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 of the connecting portion 35. The flange portion 34 is positioned 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 the lower plate 32L of the lifting frame 32, which will be described later.

[0082] 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 disposed between the upper plate 32u and the lower plate 32L. The outer periphery of the flange 34 is movable vertically between the upper plate 32u and the lower plate 32L.

[0083] The lifting frame 32 and the blocking member 33 include: a positioning protrusion 41 and a positioning hole 42, which restrict the relative movement of the lifting frame 32 and the blocking member 33 in the circumferential direction (around the rotation axis A1) when the blocking member 33 is supported by the lifting frame 32. Figure 2 An example is shown where multiple positioning protrusions 41 are provided on the lower plate 32L and multiple positioning holes 42 are provided on the flange portion 34. The positioning protrusions 41 may also be provided on the flange portion 34, and the positioning holes 42 may also be provided on the lower plate 32L.

[0084] Multiple positioning protrusions 41 are arranged on a circle having a center on the rotation axis A1. Similarly, multiple positioning holes 42 are arranged on a circle having a center on the rotation axis A1. The multiple positioning holes 42 are arranged circumferentially with the same regularity as the multiple positioning protrusions 41. The positioning protrusions 41, which protrude upward from the upper surface of the lower plate 32L, are inserted into the positioning holes 42, which extend upward from the lower surface of the flange portion 34. This restricts the circumferential movement of the blocking member 33 relative to the lifting frame 32.

[0085] The blocking member 33 includes a plurality of upper support portions 43 protruding downward from the inner surface of the blocking member 33. The rotary chuck 10 includes a plurality of lower support portions 44 that respectively support the plurality of upper support portions 43. The plurality of upper support portions 43 are surrounded by the cylindrical portion 37 of the blocking member 33. The lower end of the upper support portion 43 is positioned higher than the lower end of the cylindrical portion 37. The radial distance from the rotation axis A1 to the upper support portion 43 is greater than the radius of the substrate W. Similarly, the radial distance from the rotation axis A1 to the lower support portion 44 is greater than the radius of the substrate W. The lower support portion 44 protrudes upward from the upper surface 12u of the rotating base 12. The lower support portion 44 is positioned further outward than the chuck pin 11.

[0086] Multiple upper support portions 43 are arranged on a circle having a center on the rotation axis A1. Similarly, multiple lower support portions 44 are arranged on a circle having a center on the rotation axis A1. The multiple lower support portions 44 are arranged circumferentially with the same regularity as the multiple upper support portions 43. The multiple lower support portions 44 rotate together with the rotating base 12 about the rotation axis A1. The rotation angle of the rotating base 12 is changed by the rotary motor 14. When the rotating base 12 is configured at a reference rotation angle, in a top view, the multiple upper support portions 43 overlap with the multiple lower support portions 44 respectively.

[0087] The blocking member lifting unit 31 is connected to the lifting frame 32. When the blocking member 33's flange 34 is supported by the lower plate 32L of the lifting frame 32, the blocking member lifting unit 31 lowers the lifting frame 32, and the blocking member 33 also lowers. When the rotating base 12 is configured such that, in a top view, the multiple upper support portions 43 overlap with the multiple lower support portions 44 at a reference rotation angle, the lower end of the upper support portion 43 contacts the upper end of the lower support portion 44. Thus, the multiple upper support portions 43 are supported by the multiple lower support portions 44.

[0088] After the upper support portion 43 of the blocking member 33 contacts the lower support portion 44 of the rotary chuck 10, when the lifting unit 31 of the blocking member 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 separates 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 central nozzle 45 move downward relative to the blocking member 33, the height difference between the lower end of the central nozzle 45 and the lower surface 36L of the circular plate portion 36 of the blocking member 33 decreases. At this time, the lifting frame 32 is positioned at a height (the lower position described later) where the flange portion 34 of the blocking member 33 will not contact the upper plate 32u of the lifting frame 32.

[0089] The blocking component lifting unit 31 positions the lifting frame 32 in the upper position. Figure 3 The position shown) to the next position ( Figure 2 The upper position is where the positioning protrusion 41 is inserted into the positioning hole 42 and the flange 34 of the blocking member 33 contacts the lower plate 32L of the lifting frame 32. That is, the upper position is where the blocking member 33 is suspended from the lifting frame 32. The lower position is 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 where the connection between the lifting frame 32 and the blocking member 33 is released and the blocking member 33 does not contact any part of the lifting frame 32.

[0090] 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 positioned further 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 blocked not only from the ambient gas above the blocking member 33, but also from the ambient gas 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.

[0091] Furthermore, when the lifting frame 32 and the blocking member 33 are in the lower position, even if the blocking member 33 rotates relative to the lifting frame 32 about the rotation axis A1, the blocking member 33 will 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 engage, thereby limiting the relative circumferential movement of the upper support portion 43 and the lower support portion 44. In this state, when the rotating motor 14 rotates, the torque of the rotating motor 14 is transmitted to the blocking member 33 via the upper support portion 43 and the lower support portion 44. Therefore, the blocking member 33 rotates in the same direction and at the same speed as the rotating base 12 when the lifting frame 32 and the central nozzle 45 are stationary.

[0092] The central nozzle 45 includes: multiple liquid outlets for dispensing liquid; and a gas outlet for dispensing gas. The multiple liquid outlets include: a chemical outlet 46 for dispensing chemical solution; an etchant outlet 47 for dispensing etchant; and an upper rinsing liquid outlet 48 for dispensing rinsing liquid. The gas outlet is an upper gas outlet 49 that dispenses inactive gas. The chemical outlet 46, etchant outlet 47, and upper rinsing liquid outlet 48 open at the lower end of the central nozzle 45. The upper gas outlet 49 opens on the outer peripheral surface of the central nozzle 45.

[0093] The etching solution is, for example, a liquid comprising at least one of the following: sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, acetic acid, ammonia, hydrogen peroxide solution, organic acid (e.g., citric acid, oxalic acid, etc.), organic base (e.g., TMAH), surfactant, polyhydric alcohol, and corrosion inhibitor. Sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, acetic acid, ammonia, hydrogen peroxide solution, citric acid, oxalic acid, and TMAH can also be used as etching solutions.

[0094] Figure 2 Examples are shown where the drug solution is DHF (dilute hydrofluoric acid). Furthermore, Figure 2Examples are shown where the flushing fluid supplied to the central nozzle 45 is pure water and the inert gas supplied to the central nozzle 45 is nitrogen. The flushing fluid supplied to the central nozzle 45 may also be a flushing fluid other than pure water. The inert gas supplied to the central nozzle 45 may also be an inert gas other than nitrogen.

[0095] The substrate processing apparatus 1 includes: a chemical solution pipe 50 for guiding chemical solution to a central nozzle 45; a chemical solution valve 51 installed on the chemical solution pipe 50; an etchant pipe 52 for guiding etchant to the central nozzle 45; an etchant valve 53 installed on the etchant pipe 52; an upper rinsing solution pipe 54 for guiding rinsing solution to the central nozzle 45; and an upper rinsing solution valve 55 installed on the upper rinsing solution pipe 54. The substrate processing apparatus 1 also includes: an upper gas pipe 56 for guiding gas to the central nozzle 45; an upper gas valve 57 installed on the upper gas pipe 56; and an upper gas flow rate regulating valve 58 for changing the flow rate of gas supplied from the upper gas pipe 56 to the central nozzle 45.

[0096] When the chemical solution valve 51 is opened, the chemical solution is supplied to the central nozzle 45 and sprayed downwards from the chemical solution outlet 46, which opens at the lower end of the central nozzle 45. When the etching solution valve 53 is opened, the etching solution is supplied to the central nozzle 45 and sprayed downwards from the etching solution outlet 47, which opens at the lower end of the central nozzle 45. When the upper rinsing solution valve 55 is opened, the rinsing solution is supplied to the central nozzle 45 and sprayed downwards from the upper rinsing solution outlet 48, which opens at the lower end of the central nozzle 45. Therefore, the processing liquid, such as the chemical solution, is supplied to the upper surface of the substrate W.

[0097] When the upper gas valve 57 is opened, nitrogen gas guided by the upper gas piping 56 is supplied to the central nozzle 45 at a flow rate corresponding to the opening of the upper gas flow rate regulating valve 58, and is ejected obliquely downward from the upper gas outlet 49, which has an opening on the outer peripheral surface of the central nozzle 45. Then, the nitrogen gas flows circumferentially and downward within the upper cylindrical passage 39. Nitrogen gas reaching the lower end of the upper cylindrical passage 39 flows downward from the lower end of the upper cylindrical passage 39. Then, the nitrogen gas flows radially in all directions within 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 gas, thereby reducing the oxygen concentration in the ambient gas. The oxygen concentration in 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 rate regulating valve 58. The upper gas valve 57 and the upper gas flow rate regulating valve 58 are included in the ambient gas oxygen concentration changing unit.

[0098] Figure 4 A graph illustrating an example of the relationship between the etching rate of the three crystalline faces of silicon and the concentration of propylene glycol in the etching solution. Figure 5Aas well as Figure 5B This diagram illustrates the mechanism by which a compound is assumed to impede the contact between hydroxide ions and polycrystalline silicon. Figure 4 , Figure 5A as well as Figure 5B In this context, "PG" represents propylene glycol.

[0099] The substrate processing apparatus 1 supplies the substrate W with an etching solution that dissolves a portion of the substrate W by etching it, and a compound that reduces the anisotropy of the etching solution relative to single-crystal silicon, or mixes them beforehand and supplies them to the substrate W.

[0100] The etching solution is an alkaline liquid that does not etch or barely etches non-etchable objects such as silicon oxide and silicon nitride, but etches objects representing at least one of monocrystalline silicon, polycrystalline silicon, and amorphous silicon 96 (refer to...). Figure 5A The pH (power of hydrogen) of the etching solution is, for example, 12 or higher. Provided the processing conditions are the same, the amount of material etched per unit time is greater than the amount of material etched per unit time.

[0101] The etching solution is a liquid used for anisotropic etching of monocrystalline silicon (including monocrystalline silicon in polycrystalline silicon). That is, provided the processing conditions are the same, when etching the (110), (100), and (111) planes of silicon with the etching solution, the etching rate of the (110) plane is the highest, and the etching rate of the (111) plane is the lowest. Therefore, the etching rate is different for each crystal plane of silicon.

[0102] The etching solution can be an aqueous solution containing a hydroxide of an alkaline metal such as sodium or potassium (an aqueous solution of NaOH or KOH), or an aqueous solution containing a quaternary ammonium hydroxide such as TMAH. The quaternary ammonium hydroxide can be at least one of TMAH, TBAH (tetrabutyl ammonium hydroxide), TPeAH (tetrapenty lammonium hydroxide), THAH (tetrahexyl ammonium hydroxide), TEAH (tetraethyl ammonium hydroxide), TPAH (tetrapropyl ammonium hydroxide), and choline hydroxide, or other substances. These all include organic bases. Furthermore, in this paragraph, TMAH is not an aqueous solution, but rather refers to an anhydrous form. The same applies to other quaternary ammonium hydroxides such as TBAH.

[0103] When quaternary ammonium hydroxide dissolves in water, it separates into cations (positive ions) and hydroxide ions. Therefore, hydroxide ions are present in the aqueous solution of quaternary ammonium hydroxide. Similarly, hydroxide ions are also present in aqueous solutions of alkali metal hydroxides such as sodium or potassium. The compound supplied to the substrate W is a barrier substance used to prevent the hydroxide ions from contacting the etched object 96. The molecules of the barrier substance are preferably larger than hydroxide ions. Furthermore, the barrier substance is preferably a water-soluble substance. The barrier substance can also be a surfactant having both hydrophilic and hydrophobic groups. As long as it is uniformly dispersed in the etching solution, the barrier substance can also be an insoluble substance.

[0104] The etching solution is supplied to the substrate W either mixed with the compound or unmixed. The compound is a substance soluble in the etching solution. The compound can be ethylene glycol or ether, or a substance other than ethylene glycol and ether, such as glycerin. The compound can be a mixture of two or more substances of different kinds, or a mixture of two or more substances of the same kind. In the latter case, the compound can also be two or more substances belonging to any one of ethylene glycol, ether, and glycerin.

[0105] Ethylene glycol can also be any one of ethylene glycol, diethylene glycol, and propylene glycol. Propylene glycol is preferred. Ethylene glycol is an example of a substance that does not participate in the reaction between silicon (Si) and hydroxide ions (OH). That is, ethylene glycol is an example of a substance that does not react with atoms that participate in the reaction between oxygen and hydroxide ions. Ethylene glycol is an example of a substance that does not act as a catalyst in such a reaction.

[0106] When an alkaline etching solution (a mixture of the compound, hydroxide, and water) including the compound is supplied to the substrate W, the concentration of the hydroxide, such as TMAH, is, for example, 0.1 wt% to 25 wt%, and the concentration of the compound is, for example, 0.001 wt% to 40 wt%. The concentration of the hydroxide is preferably 0.25 wt% to 20 wt%. The concentration of the compound is preferably 0.5 wt% to 30 wt%.

[0107] Figure 5A as well as Figure 5B An example is shown of supplying an etching solution (a mixture of etching solution and propylene glycol) including propylene glycol as an example of a compound to a polycrystalline silicon object 96, which is being etched. Figure 5A as well as Figure 5B "Positive ions" and "OH-" - "The substance that has been separated from the hydroxides (alkali metal hydroxides or quaternary ammonium hydroxides) contained in the etching solution."

[0108] The silicon contained in polycrystalline silicon and other etched objects 96 is expressed as follows: "Si + 4OH - →Si(OH)4+4e - The material reacts with hydroxide ions. Therefore, the silicon contained in the etched object 96 dissolves in the etching solution, and the etching of the etched object 96 continues. The compounds contained in the etching solution act as a steric barrier to the hydroxide ions. That is, compounds suspended in the etching solution or adsorbed and coordinated in the polycrystalline silicon prevent hydroxide ions in the etching solution from moving towards the polycrystalline silicon. Therefore, the number of hydroxide ions reaching the polycrystalline silicon decreases, and the etching rate of the polycrystalline silicon decreases. It is believed that this mechanism is due to the compounds hindering the contact between hydroxide ions and polycrystalline silicon.

[0109] Although the decrease in etching rate occurs across multiple crystal planes of silicon contained in polycrystalline silicon, the etching rate decreases relatively significantly on the crystal planes with the highest etching rates. Therefore, the difference in etching rates across multiple crystal planes decreases, and the anisotropy of the etchant for monocrystalline silicon decreases. That is, the polycrystalline silicon is etched uniformly, regardless of the orientation of the silicon faces exposed on the polycrystalline silicon surface. It is believed that through this mechanism, the polycrystalline silicon is etched with a uniform etching amount regardless of its location.

[0110] Figure 4 The etch rates of the (110), (100), and (111) planes of monocrystalline silicon are shown in the figures obtained by etching with three different concentrations of propylene glycol-based TMAH (zero, first, and second concentrations). Figure 4 The etching conditions for the measurements shown are the same except for the concentration of propylene glycol in the TMAH. For example, the TMAH temperature is 40°C, and the concentration of TMAH without added propylene glycol is 5 wt% (mass percentage concentration). The dissolved oxygen concentration of the TMAH is reduced beforehand.

[0111] like Figure 4 As shown, when the concentration of propylene glycol is zero, the etching rate of the (110) face is the highest, and the etching rate of the (111) face is the lowest. (Refer to...) Figure 4 The three curves show that the etching rate decreases when propylene glycol is added to TMAH. Moreover, the etching rate decreases for all crystal planes as the concentration of propylene glycol increases.

[0112] However, within the range of propylene glycol concentration from zero to the first concentration, the etching rate of the (110) and (100) faces decreases sharply, while the etching rate of the (111) face decreases very slowly. Therefore, within this range, the difference between the maximum and minimum etching rates decreases as the propylene glycol concentration increases.

[0113] When the concentration of propylene glycol exceeds the first concentration, although the rate of decrease in etching rate (the ratio of the absolute value of the change in etching rate to the absolute value of the change in propylene glycol concentration) decreases, the rate of decrease in etching rate for the (110) and (100) faces is greater than that for the (111) face in the range near the middle between the first and second concentrations. Therefore, even when the concentration of propylene glycol is in the range near the middle between the first and second concentrations, the difference between the maximum and minimum etching rates decreases as the concentration of propylene glycol increases.

[0114] Thus, when propylene glycol is added to the TMAH used to exhibit anisotropy in monocrystalline silicon, the difference between the maximum and minimum etching rates of the planar orientation selectivity decreases, and the anisotropy of the TMAH relative to monocrystalline silicon decreases. On the other hand, within the range of propylene glycol concentration near the middle of the first and second concentrations, the etching rates of the (110) and (100) planes decrease at a large rate as the concentration of propylene glycol increases. Therefore, the concentration of propylene glycol can be set according to the desired etching uniformity and the desired etching rate.

[0115] For example, propylene glycol or other substances that prevent excessive addition of solvents can be introduced into the etching solution. Based on... Figure 4 The results shown indicate that while the anisotropy mitigation effect is relatively small when propylene glycol is added in small amounts (e.g., around 5 wt% to 10 wt%), a significant anisotropy mitigation effect is confirmed when propylene glycol is added in large amounts (e.g., more than 20 wt%), i.e., when excessive propylene glycol is added. Conversely, the etching rate decreases; therefore, the concentration of propylene glycol should be selected based on the required quality and the allowable processing time.

[0116] Figure 4 The observed tendency was also confirmed in combinations other than TMAH and propylene glycol. Therefore, the etching solution is not limited to TMAH, and the compound is not limited to propylene glycol. Furthermore, Figure 4 The tendency shown is conceived not only in the case where the etchant containing the compound is supplied to the object to be etched 96, but also in the case where the compound and the etchant are supplied separately to the substrate W and the compound and the etchant are mixed on the object to be etched 96. Therefore, it is also possible to supply the compound and the etchant separately to the substrate W.

[0117] Provided that all other conditions are the same (including combinations of substances in the case of a mixture of two or more substances), the etching rates of at least one of the silicon (110), (100), and (111) surfaces will differ when the type of compound supplied to the object to be etched 96 is different. Therefore, the type of compound can be selected based on the required quality and the allowable processing time.

[0118] When the etchant is supplied to the object to be etched instead of the compound, the etching rate of the (110) and (100) surfaces increases by a larger amount than the change in the etching rate of the (111) surface when the temperature of the etchant rises. Furthermore, in this case, the etching rate of the (110) and (100) surfaces decreases by a larger amount than the change in the etching rate of the (111) surface when the temperature of the etchant decreases.

[0119] Therefore, when the etching solution is supplied to the object being etched 96 instead of the compound, the difference between the minimum and maximum etching rates of silicon increases as the temperature of the etching solution rises. Conversely, when the etching solution is supplied to the object being etched 96 instead of the compound, the difference between the minimum and maximum etching rates of silicon decreases as the temperature of the etching solution decreases. These phenomena also occur when both the etching solution and the compound are supplied to the object being etched 96. Therefore, the temperatures of the etching solution and the compound can be set according to the required quality and the allowable processing time.

[0120] Figure 6 This is a schematic diagram of a processing liquid supply unit 61 of a substrate processing apparatus 1 for supplying processing liquids such as etching solution to a substrate W. Figure 6 An example is shown where the etchant is mixed with a compound before being supplied to the substrate W.

[0121] The substrate processing apparatus 1 includes a processing liquid supply unit 61 for supplying processing liquids such as etching solution to the substrate W. The aforementioned central nozzle 45, etching liquid piping 52, and etching liquid valve 53 are included in the processing liquid supply unit 61. The processing liquid supply unit 61 is an example of a first etching unit and a second etching unit.

[0122] In addition to the center nozzle 45, the processing fluid supply unit 61 also includes: a raw material tank 62 for storing the raw material (undiluted alkaline etching solution); a first diluent tank 70 for storing a first diluent for diluting the raw material of the etching solution; and a second diluent tank 75 for storing a second diluent for diluting the raw material of the etching solution.

[0123] The first and second diluents are liquids with the same composition but different dissolved oxygen concentrations. Figure 6 Examples of first and second diluents are shown, in which pure water (DIW) containing the aforementioned compounds has been dissolved. The dissolved oxygen concentration of the first diluent is lower than that of the second diluent. Both the first and second diluents can be alkaline etching solutions, provided the hydroxide concentration is lower than that of the original etching solution.

[0124] The stock solution in the stock solution tank 62 is supplied to the central nozzle 45 via the mixing valve 80. Similarly, the first diluent in the first diluent tank 70 is supplied to the central nozzle 45 via the mixing valve 80, and the second diluent in the second diluent tank 75 is supplied to the central nozzle 45 via the mixing valve 80. The etchant stock solution is mixed with at least one of the first and second diluents within the mixing valve 80. Thus, a diluted stock solution, i.e., the etchant solution, is generated and supplied to the central nozzle 45.

[0125] The processing fluid supply unit 61 may also include an in-line mixer 81, which agitates the etching fluid that has passed through the mixing valve 80 before it is ejected from the central nozzle 45. Figure 6 This illustrates an example where the line mixer 81 is positioned upstream of the etching solution valve 53. The line mixer 81 is a static mixer and includes: a pipe 81p installed in the raw liquid piping 67; and stirring fins 81f disposed within the pipe 81p, which are twisted around an axis extending in the direction of liquid flow.

[0126] The processing fluid supply unit 61 includes: a circulation piping 63 for circulating the raw fluid in the raw fluid tank 62; a circulation pump 64 for delivering the raw fluid in the raw fluid tank 62 to the circulation piping 63; a filter 66 for removing particulate matter and other foreign matter from the raw fluid returning to the raw fluid tank 62; and a temperature regulator 65 for changing the temperature of the raw fluid in the raw fluid tank 62 by heating or cooling the raw fluid.

[0127] The circulation pump 64 continuously delivers the raw liquid from the raw liquid tank 62 to the circulation piping 63. The raw liquid in the raw liquid tank 62 flows into the circulation piping 63 through its upstream end and returns to the raw liquid tank 62 through its downstream end. Thus, the raw liquid circulates through the circulation path formed by the raw liquid tank 62 and the circulation piping 63.

[0128] Temperature regulator 65 maintains the temperature of the stock solution in stock solution tank 62 at a constant temperature, either higher or lower than room temperature (e.g., 20°C to 30°C). Temperature regulator 65 can be installed in circulation piping 63 or disposed within stock solution tank 62. Figure 6 This is an example illustrating the former. The temperature regulator 65 can be a heater that heats the liquid at a temperature higher than room temperature, or a cooler that cools the liquid at a temperature lower than room temperature, or it can have both heating and cooling functions.

[0129] The processing fluid supply unit 61 also includes: a raw fluid piping 67 that guides the raw fluid from the circulation piping 63 to the central nozzle 45; a flow regulating valve 69 that changes the flow rate of the raw fluid flowing downstream in the raw fluid piping 67; and an in-line heater 68 that heats the raw fluid flowing into the raw fluid piping 67.

[0130] The raw liquid in the circulating pipe 63 flows into the raw liquid pipe 67 through the upstream end of the raw liquid pipe 67, and is supplied to the mixing valve 80 through the downstream end of the raw liquid pipe 67. At this time, the raw liquid is supplied to the mixing valve 80 at a flow rate corresponding to the opening of the flow regulating valve 69. When raw liquid at a temperature higher than that in the raw liquid tank 62 is supplied to the mixing valve 80, the raw liquid is heated by the inline heater 68 before being supplied to the mixing valve 80.

[0131] The processing fluid supply unit 61 includes: a first diluent pipe 71 for guiding the first diluent from the first diluent tank 70 to the central nozzle 45; a first diluent pump 72 for delivering the first diluent in the first diluent tank 70 to the first diluent pipe 71; a filter 73 for removing particulate matter and other foreign objects from the first diluent flowing toward the central nozzle 45; and a flow regulating valve 74 for changing the flow rate of the first diluent flowing downstream in the first diluent pipe 71.

[0132] The processing fluid supply unit 61 further includes: a second diluent piping 76 for guiding the second diluent from the second diluent tank 75 to the central nozzle 45; a second diluent pump 77 for delivering the second diluent in the second diluent tank 75 to the second diluent piping 76; a filter 78 for removing particulate matter and other foreign objects from the second diluent flowing toward the central nozzle 45; and a flow regulating valve 79 for adjusting the flow rate of the second diluent flowing downstream in the second diluent piping 76.

[0133] When circulating the first diluent in the first diluent tank 70, the same configuration as the original solution can be used. That is, only the circulation piping 63 and circulation pump 64 for the first diluent need to be installed. When supplying the first diluent, which is higher or lower than room temperature, to the mixing valve 80, only one of the temperature regulator 65 for the first diluent and the line heater 68 needs to be installed. The same applies to the second diluent.

[0134] The mixing valve 80 includes: multiple valves that can be opened and closed individually; and multiple flow paths that are connected to the multiple valves. Figure 6 An example is shown where the mixing valve 80 includes three valves (first valve V1, second valve V2, and third valve V3), three inlet ports (first inlet port Pi1, second inlet port Pi2, and third inlet port Pi3), and one outlet port Po. The stock solution piping 67 is connected to the first inlet port Pi1. The first diluent piping 71 is connected to the second inlet port Pi2, and the second diluent piping 76 is connected to the third inlet port Pi3. The etching solution piping 52 is connected to the outlet port Po.

[0135] When the first valve V1 is opened, the raw solution in the raw solution pipe 67 flows into the mixing valve 80 through the first inlet port Pil and is discharged from the outlet port Po to the etching solution pipe 52. Similarly, when the second valve V2 is opened, the first diluent in the first diluent pipe 71 flows into the mixing valve 80 through the second inlet port Pi2 and is discharged from the outlet port Po to the etching solution pipe 52. When the third valve V3 is opened, the second diluent in the second diluent pipe 76 flows into the mixing valve 80 through the third inlet port Pi3 and is discharged from the outlet port Po to the etching solution pipe 52.

[0136] When the first valve V1 and the second valve V2 are opened, the raw solution is supplied to the mixing valve 80 at a flow rate corresponding to the opening of the flow regulating valve 69, and the first diluent is supplied to the mixing valve 80 at a flow rate corresponding to the opening of the flow regulating valve 74. Thus, the raw etching solution diluted by the first diluent is supplied from the mixing valve 80 to the etching solution piping 52 and sprayed from the central nozzle 45 toward the substrate W.

[0137] When the first valve V1 and the third valve V3 are opened, the raw solution is supplied to the mixing valve 80 at a flow rate corresponding to the opening of the flow regulating valve 69, and the second diluent is supplied to the mixing valve 80 at a flow rate corresponding to the opening of the flow regulating valve 79. Thus, the raw etching solution diluted by the second diluent is supplied from the mixing valve 80 to the etching solution piping 52 and sprayed from the central nozzle 45 toward the substrate W.

[0138] When the first valve V1, the second valve V2, and the third valve V3 are opened, the original solution, the first diluent, and the second diluent are supplied to the mixing valve 80. The original solution of the etching solution, diluted by the first and second diluents, is then supplied from the mixing valve 80 to the etching solution piping 52. The ratio of the first and second diluents in the etching solution is adjusted by the opening of the flow regulating valves 74 and 79.

[0139] Regardless of the type of diluent used to dilute the stock solution, the ratio of the diluent (at least one of the first and second diluents) to the stock solution remains constant. For example, if the ratio of the diluent (volume of diluent / volume of stock solution) when diluting the stock solution with only the first diluent is X, then the ratio of the diluent when diluting the stock solution with only the second diluent is also X. The ratio of the diluent when diluting the stock solution with both the first and second diluents is also X. Therefore, as long as the amount of stock solution supplied to the mixing valve 80 is constant, the stock solution is diluted with a fixed amount of diluent. The proportion of the stock solution contained in the etching solution can be smaller, larger, or equal to the proportion of the diluent contained in the etching solution.

[0140] The substrate processing apparatus 1 has a dissolved oxygen concentration adjustment unit for adjusting the dissolved oxygen concentration of the etching solution. Figure 6 The following example is shown: the dissolved oxygen concentration adjustment unit includes: a stock solution adjustment unit 82A for adjusting the dissolved oxygen concentration of the stock solution; a first diluent adjustment unit 82B for adjusting the dissolved oxygen concentration of the first diluent; and a second diluent adjustment unit 82C for adjusting the dissolved oxygen concentration of the second diluent.

[0141] The feedstock adjustment unit 82A includes a gas piping 83 that supplies gas to the feedstock tank 62, causing the gas to dissolve into the feedstock in the tank 62. The feedstock adjustment unit 82A also includes: an inactive gas piping 84 that supplies inactive gas to the gas piping 83; an inactive gas valve 85 that switches between an open state and a closed state, wherein the open state is when inactive gas flows from the inactive gas piping 84 to the gas piping 83, and the closed state is when inactive gas is blocked by the inactive gas piping 84; and a flow adjustment valve 86 that changes the flow rate of the inactive gas supplied from the inactive gas piping 84 to the gas piping 83.

[0142] Gas piping 83 is a bubbler piping system, including a gas outlet 83p disposed within the raw liquid tank 62. When the inactive gas valve 85 is switched from closed to open, inactive gases such as nitrogen are ejected from the gas outlet 83p at a flow rate corresponding to the opening of the flow regulating valve 86. Therefore, multiple bubbles are formed in the raw liquid within the raw liquid tank 62, and the inactive gases dissolve into the raw liquid. At this time, dissolved oxygen is discharged from the raw liquid, thereby reducing the dissolved oxygen concentration of the raw liquid. The dissolved oxygen concentration of the raw liquid within the raw liquid tank 62 is changed by altering the flow rate of nitrogen ejected from the gas outlet 83p.

[0143] The first diluent adjustment unit 82B includes a gas piping 87 that supplies gas to the first diluent tank 70, causing the gas to dissolve into the first diluent tank 70. The first diluent adjustment unit 82B also includes: an inactive gas piping 88 for supplying inactive gas to the gas piping 87; an inactive gas valve 89 that opens and closes between an open state (where the inactive gas flows from the inactive gas piping 88 to the gas piping 87) and a closed state (where the inactive gas is blocked by the inactive gas piping 88); and a flow adjustment valve 90 that changes the flow rate of the inactive gas supplied from the inactive gas piping 88 to the gas piping 87.

[0144] Gas piping 87 is a bubble-generating piping, including a gas outlet 87p disposed in the first diluent within the first diluent tank 70. When the inactive gas valve 89 is switched from a closed state to an open state, inactive gases such as nitrogen are ejected from the gas outlet 87p at a flow rate corresponding to the opening degree of the flow regulating valve 90. Therefore, multiple bubbles are formed in the first diluent within the first diluent tank 70, and the inactive gases dissolve into the first diluent within the first diluent tank 70. At this time, dissolved oxygen is discharged from the first diluent, thereby reducing the dissolved oxygen concentration of the first diluent. The dissolved oxygen concentration of the first diluent within the first diluent tank 70 is changed by altering the flow rate of nitrogen ejected from the gas outlet 87p.

[0145] The second diluent adjustment unit 82C includes a gas piping 91 that supplies gas to the second diluent tank 75, causing the gas to dissolve into the second diluent within the tank. The second diluent adjustment unit 82C also includes: an oxygen piping 92 for supplying oxygen-containing gas to the gas piping 91; an oxygen valve 93 that switches between an open state (where oxygen-containing gas flows from the oxygen piping 92 to the gas piping 91) and a closed state (where the oxygen-containing gas is blocked by the oxygen piping 92); and a flow regulating valve 94 for changing the flow rate of the oxygen-containing gas supplied from the oxygen piping 92 to the gas piping 91. The oxygen-containing gas is an example of a dissolved gas. It can be oxygen or a mixture of oxygen and gases other than nitrogen. Figure 6 An example is shown where a dry gas (dried clean air) containing nitrogen and oxygen in a ratio of approximately 8:2 is used as the oxygen-containing gas.

[0146] Gas piping 91 is a bubble-generating piping, including a gas outlet 91p disposed in the second diluent within the second diluent tank 75. When oxygen valve 93 is switched from a closed state to an open state, oxygen-containing gas is ejected from gas outlet 91p at a flow rate corresponding to the opening degree of flow regulating valve 94. This results in the formation of multiple bubbles in the second diluent within the second diluent tank 75, and the oxygen-containing gas dissolves into the second diluent. Dry gases such as air contain oxygen at approximately 21 vol%, while nitrogen contains no oxygen or only a very small amount of oxygen. Therefore, by dissolving oxygen-containing gas in the second diluent, the dissolved oxygen concentration of the second diluent can be increased.

[0147] The dissolved oxygen concentration of the second diluent is higher than that of the first diluent and higher than that of the original solution. The dissolved oxygen concentration of the first diluent may also be higher, lower, or equal to that of the original solution. For example, the dissolved oxygen concentration of the first diluent is less than 2 ppm compared to the original solution. The dissolved oxygen concentration of the second diluent is, for example, 6 to 7 ppm. The dissolved oxygen concentration of the original solution diluted only with the first diluent is, for example, less than 2 ppm. The dissolved oxygen concentration of the original solution diluted only with the second diluent is a value between the dissolved oxygen concentration of the original solution and the dissolved oxygen concentration of the second diluent.

[0148] When the dissolved oxygen concentration of the stock solution diluted only with the first diluent is used as the first dissolved oxygen concentration, and the dissolved oxygen concentration of the stock solution diluted only with the second diluent is used as the second dissolved oxygen concentration, an etching solution with a dissolved oxygen concentration between the first and second dissolved oxygen concentrations can be prepared by diluting the stock solution with both the first and second diluents (stock solution diluted with the first and second diluents). Moreover, by changing the ratio of the first and second diluents, the dissolved oxygen concentration of the etching solution can be varied between the first and second dissolved oxygen concentrations.

[0149] The first etchant, as described later, refers to the stock etchant diluted only with the first diluent, or the stock etchant diluted with both the first and second diluents. The second etchant, as described later, refers to the stock etchant diluted only with the second diluent, or the stock etchant diluted with both the first and second diluents. When both the first and second etchants include both the first and second diluents, the ratio of the first and second diluents is adjusted so that the dissolved oxygen concentration of the second etchant is higher than that of the first etchant.

[0150] Figure 7 This is a block diagram showing the electrical structure of the substrate processing apparatus 1.

[0151] The control device 3 is a computer comprising a main computer body 3a and peripheral devices 3d connected to the main computer body 3a. The main computer body 3a includes: a CPU (central processing unit) 3b, which executes various commands; and a main storage device 3c, which stores information. The peripheral devices 3d include: an auxiliary storage device 3e, which stores information such as program P; a reading device 3f, which reads information from removable media RM; and a communication device 3g, which communicates with other devices such as the host computer.

[0152] The control device 3 includes an input device and a display device. The input device is operated when an operator, such as a user or maintenance personnel, inputs information into the board processing device 1. The information is displayed on the screen of the display device. The input device can be any of a keyboard, a pointing device, or a touch panel, or other devices. Alternatively, the board processing device 1 may be equipped with a touch panel display that serves as both an input device and a display device.

[0153] CPU 3b executes program P stored in auxiliary storage device 3e. Program P in auxiliary storage device 3e may be a program P pre-installed on control device 3, a program P transferred to auxiliary storage device 3e from removable media RM via reading device 3f, or a program P transferred to auxiliary storage device 3e from external device such as host computer via communication device 3g.

[0154] Auxiliary storage device 3e and removable media RM are non-volatile memories that retain storage even without power supply. Auxiliary storage device 3e is, for example, a magnetic storage device such as a hard disk drive. Removable media RM is, for example, a semiconductor memory such as a compact disc (CD) or a memory card. Removable media RM is an example of a computer-readable storage medium storing a program P. Removable media RM is a non-transitory tangible storage medium.

[0155] The auxiliary storage device 3e stores multiple recipes. Each recipe specifies the processing content, processing conditions, and processing sequence for the substrate W. The multiple recipes differ from each other in at least one of the processing content, processing conditions, and processing sequence for the substrate W. The control device 3 controls the substrate processing device 1 to process the substrate W according to the recipe specified by the host computer. The control device 3 is programmed to execute the processes described later.

[0156] Figure 8 This is a process diagram illustrating an example of the processing of substrate W performed by substrate processing apparatus 1. Hereinafter, refer to... Figure 1A , Figure 2 , Figure 3 , Figure 6 as well as Figure 8 .

[0157] When the substrate W is processed by the substrate processing apparatus 1, a transfer process is performed to move the substrate W into the chamber 4. Figure 8 Step S1).

[0158] Specifically, with the lifting frame 32 and the blocking member 33 in the upper position and all the protective covers 25 in the lower position, the central robot CR, while supporting the substrate W with its hand H1, enters the chamber 4. Next, with the surface of the substrate W facing upwards, the central robot CR places the substrate W on the hand H1 onto multiple chuck pins 11. Then, the multiple chuck pins 11 are pressed against the outer peripheral surface of the substrate W and hold the substrate W. After placing the substrate W on the rotating chuck 10, the central robot CR retracts the hand H1 from the interior of the chamber 4.

[0159] Next, the upper gas valve 57 and the lower gas valve 21 are opened, and nitrogen gas 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. This reduces the oxygen concentration in the ambient gas in contact with the substrate W. 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 one of the protective covers 25 from the lower position to the upper position. At this time, the rotating base 12 is maintained at a reference rotation angle where, when viewed from above, the multiple upper supports 43 overlap with the multiple lower supports 44. Therefore, the upper supports 43 of the blocking member 33 are supported by the lower supports 44 of the rotating base 12, and the blocking member 33 moves away from the lifting frame 32. Then, the rotary motor 14 is driven, thereby starting to rotate the substrate W. Figure 8 Step S2).

[0160] Next, a drug supply process is performed in which DHF, as an example of a drug solution, is supplied to the upper surface of the substrate W. Figure 8 Step S3).

[0161] Specifically, with the blocking member 33 in the lower position, the liquid valve 51 is opened, and the central nozzle 45 begins to spray DHF. The DHF sprayed from the central nozzle 45 collides with the center of the upper surface of the substrate W and flows outward along the rotating upper surface of the substrate W. This forms a liquid film of DHF covering the entire upper surface of the substrate W, supplying DHF to the entire upper surface of the substrate W. After a predetermined time has elapsed since the liquid valve 51 was opened, the liquid valve 51 is closed, thereby stopping the spraying of DHF.

[0162] Next, a first rinsing solution supply process is performed, in which pure water, as an example of a rinsing solution, is supplied to the upper surface of the substrate W. Figure 8 Step S4).

[0163] Specifically, with the blocking member 33 in the lower position, the upper flushing fluid valve 55 is opened, and the central nozzle 45 begins to spray pure water. The pure water colliding with the center of the upper surface of the substrate W flows outward along the rotating upper surface of the substrate W. The DHF on the substrate W is rinsed by the pure water sprayed from the central nozzle 45. As a result, a liquid film of pure water covering the entire upper surface of the substrate W is formed. After a predetermined time has elapsed since the upper flushing fluid valve 55 was opened, the upper flushing fluid valve 55 is closed, thereby stopping the spraying of pure water.

[0164] Next, a first etching process is performed, in which a first etching solution, as an example of an etching solution, is supplied to the upper surface of the substrate W. Figure 8 Step S5).

[0165] Specifically, with the blocking member 33 in the lower position, the first valve V1 and the second valve V2 of the mixing valve 80 are opened, and the etching solution valve 53 is opened. As a result, the first etching solution, i.e., the original etching solution diluted with the first diluent, is supplied to the central nozzle 45, and the central nozzle 45 begins to spray the first etching solution. Before the first etching solution begins to spray, the protective cover lifting unit 27 can also move at least one protective cover 25 in the vertical direction to switch the protective cover 25 that receives the liquid discharged from the substrate W. The first etching solution that collides with the center of the upper surface of the substrate W flows outward along the rotating upper surface of the substrate W. The pure water on the substrate W is replaced by the first etching solution sprayed from the central nozzle 45. Thus, a liquid film of the first etching solution covering the entire upper surface of the substrate W is formed.

[0166] After the liquid film of the first etchant is formed, a second etching process is performed in which a second etchant, another example of an etchant, is supplied to the upper surface of the substrate W. Figure 8 Step S6).

[0167] Specifically, with the first valve V1 of the mixing valve 80 and the etching solution valve 53 open, the second valve V2 of the mixing valve 80 is closed, and the third valve V3 of the mixing valve 80 is opened. At this time, the flow regulating valve 69 can also be changed as needed (see...). Figure 6 The opening degree of the mixing valve 80. When the second valve V2 of the mixing valve 80 is closed and the third valve V3 of the mixing valve 80 is opened, the supply of the first diluent to the mixing valve 80 stops, and the supply of the second diluent to the mixing valve 80 begins. As a result, the second etchant, i.e., the original etchant diluted with the second diluent, is supplied to the central nozzle 45, and the central nozzle 45 begins to spray the second etchant. Before the second etchant is sprayed, the protective cover lifting unit 27 can also move at least one protective cover 25 in the vertical direction to switch the protective cover 25 that receives the liquid discharged from the substrate W.

[0168] With the blocking member 33 in the lower position, a second etchant is ejected from the central nozzle 45 toward the center of the upper surface of the substrate W. The second etchant, colliding with the center of the upper surface of the substrate W, flows outward along the rotating upper surface of the substrate W. The first etchant on the substrate W is replaced by the second etchant ejected from the central nozzle 45. As a result, a liquid film of the second etchant covering the entire upper surface of the substrate W is formed. Then, all valves of the mixing valve 80 (first valve V1, second valve V2, and third valve V3) are closed, and the etchant valve 53 is closed. Thus, with the entire upper surface of the substrate W covered by the liquid film of the second etchant, the ejection of the second etchant from the central nozzle 45 stops.

[0169] Next, a second rinsing solution supply process is performed, in which pure water, as an example of a rinsing solution, is supplied to the upper surface of the substrate W. Figure 8 Step S7).

[0170] Specifically, with the blocking member 33 in the lower position, the upper flushing fluid valve 55 is opened, and the central nozzle 45 begins to spray pure water. The pure water colliding with the center of the upper surface of the substrate W flows outward along the rotating upper surface of the substrate W. The second etching solution on the substrate W is rinsed by the pure water sprayed from the central nozzle 45. As a result, a liquid film of pure water covering the entire upper surface of the substrate W is formed. After a predetermined time has elapsed since the upper flushing fluid valve 55 was opened, the upper flushing fluid valve 55 is closed, thereby stopping the spraying of pure water.

[0171] Next, a drying process is performed to dry the substrate W by rotating it. Figure 8 Step S8).

[0172] Specifically, with the blocking member 33 in the lower position, the rotary motor 14 accelerates the substrate W in the rotational direction and rotates the substrate W at a high speed (e.g., several thousand rpm) greater than the rotational speed of the substrate W during the period from the liquid supply step to the second rinsing liquid supply step. This removes liquid from the substrate W, thereby drying it. After a predetermined time has elapsed since the substrate W began rotating at high speed, the rotary motor 14 stops rotating. At this time, the rotary motor 14 stops the rotating base 12 by a reference rotation angle. This stops the rotation of the substrate W. Figure 8 Step S9).

[0173] Next, the substrate W is removed from chamber 4 in a removal process. Figure 8 Step S10).

[0174] 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. Furthermore, the upper gas valve 57 and the lower gas valve 21 are closed, stopping the emission of nitrogen gas from the upper central opening 38 of the blocking member 33 and the lower central opening 18 of the rotating base 12. Then, the central robot CR moves its hand H1 into the chamber 4. After the multiple chuck pins 11 release the substrate W from its grip, the central robot CR supports the substrate W on the rotating chuck 10 with its hand H1. Then, while supporting the substrate W with its hand H1, the central robot CR retracts its hand H1 from inside the chamber 4. Thus, the processed substrate W is removed from the chamber 4.

[0175] Figure 9A It is shown in Figure 8 The schematic diagram shows an example of a cross-section of the substrate W before the first etching solution is supplied, in one example of the processing of the substrate W shown. Figure 9B It is shown in Figure 8 The schematic diagram shows an example of the cross-section of the substrate W after the first etchant has been supplied, in one example of the processing of the substrate W shown. Figure 9C It is shown in Figure 8 The schematic diagram shows an example of the cross-section of the substrate W after the second etching solution has been supplied, in one example of the processing of the substrate W shown.

[0176] During the drug supply process ( Figure 8 In step S3), when acidic solutions such as DHF are supplied to substrate W, the natural oxide film is removed from the surface of substrate W. Figure 9A An example of a cross-section of a substrate W with the natural oxide film removed is shown. Figure 9A The cross-section of the substrate W shown is the same as the cross-section of the substrate W before the acidic solution is supplied. A recess 95 is formed on the surface of the substrate W before the acidic solution is supplied. The recess 95 is recessed from the outermost surface of the substrate W in the thickness direction of the substrate W. The recess 95 can be a hole or a groove extending in the surface direction of the substrate W.

[0177] The width W1 of the recess 95 is smaller than the depth D1 of the recess 95. In other words, the maximum value of the spacing between the side surfaces 95s of the recess 95 is smaller than the length of the side surfaces 95s of the recess 95 in the depth direction. Before the substrate processing apparatus 1 processes the substrate W, the width W1 of the recess 95 can be constant from the entrance of the recess 95 to the bottom of the recess 95, or it can gradually change. Figure 9A An example is shown where the width W1 of the recess 95 decreases continuously as it approaches the bottom of the recess 95. The decrease in the width W1 of the recess 95 is not caused by the supply of acidic solution in the substrate processing apparatus 1, but is caused by a preprocessing step, such as a dry etching step, performed before the substrate W is placed into the substrate processing apparatus 1.

[0178] The width W1 of the recess 95 (which is at its maximum value when the width W1 of the recess 95 is not uniform) is, for example, 30 nm to 2000 nm. The depth D1 of the recess 95 is, for example, 60 nm to 4000 nm. The aspect ratio of the recess 95 (depth D1 of the recess 95 / width W1 of the recess 95) is, for example, 2 to 200. When the width W1 of the recess 95 continuously decreases as it approaches the bottom of the recess 95, the difference between the maximum and minimum width W1 of the recess 95 is, for example, 1 nm to 200 nm.

[0179] Figure 9AAn example is shown where the entire area of ​​the side surface 95s of the recess 95 is formed using polysilicon as an etching object 96. The entire area of ​​the side surface 95s of the recess 95 can also be formed using the etching object 96, or only a portion of the side surface 95s of the recess 95 can be formed using the etching object 96. In the latter case, the etching object 96 only needs to expose at least a portion of the upper part of the side surface 95s and at least a portion of the lower part of the side surface 95s. In this case, a portion of the side surface 95s can also be formed using a material other than the etching object 96, while the remaining portion of the side surface 95s is formed using the etching object 96. The upper part of the side surface 95s is the portion higher than the position that bisects the side surface 95s in the depth direction of the recess 95. The lower part of the side surface 95s is the portion lower than the position that bisects the side surface 95s in the depth direction of the recess 95.

[0180] During the drug supply process ( Figure 8 In step S3), when the acidic solution is supplied to the substrate W, the natural oxide film of the polysilicon, i.e., the silicon oxide film, is removed from the side surface 95 of the recess 95. Afterwards, a first etchant, which is alkaline and has a low dissolved oxygen concentration, is supplied to the substrate W. Figure 8 (Step S5). Because the dissolved oxygen concentration of the first etchant is low, the polysilicon exposed on the side surface 95s of the recess 95 is difficult to be oxidized by the dissolved oxygen in the first etchant. Therefore, when the first etchant is supplied to the substrate W, the side surface 95s of the recess 95 is uniformly etched at a high etching rate.

[0181] Figure 9B The cross-section of the substrate W after the supply of the acidic solution and before the supply of the first etchant is shown with a double-dotted line, and the cross-section of the substrate W after the supply of the first etchant is shown with a solid line. Since the width W1 of the recess 95 continuously decreases as it approaches the bottom of the recess 95, and the side surfaces 95s of the recess 95 are uniformly etched by the supply of the first etchant, the width W1 of the recess 95 also continuously decreases as it approaches the bottom of the recess 95 after the first etchant is supplied.

[0182] After the first etching solution is supplied to the substrate W, a second etching solution, which is alkaline and has a higher dissolved oxygen concentration than the first etching solution, is supplied to the substrate W. Figure 8 (Step S6). Therefore, all or almost all of the first etchant in contact with the substrate W is replaced by the second etchant, which enters the recess 95. Figure 9C The cross-section of the substrate W after the first etchant was supplied and before the second etchant was supplied is shown with a double-dotted line, and the cross-section of the substrate W after the second etchant was supplied is shown with a solid line.

[0183] like Figure 9CAs shown, when the second etchant is supplied to the recess 95, the dissolved oxygen (O2 in FIG. 9) contained in the second etchant comes into contact with the side surface 95s of the recess 95 near the entrance of the recess 95, causing the polysilicon, which is an example of the object 96 to be etched, to oxidize. Therefore, although only slightly, the dissolved oxygen concentration of the second etchant decreases as it flows towards the bottom of the recess 95. Even slightly away from the entrance of the recess 95, the dissolved oxygen concentration of the second etchant comes into contact with the side surface 95s of the recess 95 and is consumed. This phenomenon repeats continuously, resulting in the dissolved oxygen concentration of the second etchant continuously decreasing as it approaches the bottom of the recess 95.

[0184] Because the dissolved oxygen concentration of the second etchant is relatively high, when the second etchant is supplied to the substrate W, the side surfaces 95s of the recess 95 are oxidized by the dissolved oxygen in the second etchant. As described above, the dissolved oxygen concentration of the second etchant decreases as it approaches the bottom of the recess 95. As long as the positions in the depth direction within the recess 95 are the same, the side surfaces 95s of the recess 95 are uniformly oxidized. However, the amount of oxidation on the side surfaces 95s of the recess 95 decreases as it approaches the bottom of the recess 95. When polycrystalline silicon is oxidized, it transforms into silicon oxide, which is difficult to be etched by alkaline etchants. When monocrystalline silicon and amorphous silicon are also oxidized, they transform into silicon oxide. Therefore, compared... Figure 9C As can be seen from the solid lines and double-dotted lines, the amount of etching on the side 95s of the recess 95 increases as it approaches the bottom of the recess 95.

[0185] Since the etching amount on the side 95s of the recess 95 increases as it approaches the bottom of the recess 95, even before the substrate W is processed by the substrate processing apparatus 1, the width W1 of the recess 95 continuously decreases as it approaches the bottom of the recess 95. After the second etching solution is supplied, the width W1 of the recess 95 becomes uniform from the entrance of the recess 95 to the bottom of the recess 95, or the non-uniformity of the width W1 of the recess 95 is reduced. Therefore, even if the shape of the recess 95 when it is brought into the substrate processing apparatus 1 is different from the desired shape, the shape of the recess 95 can be made to match or be close to the desired shape after the second etching solution is supplied.

[0186] Thus, by supplying an alkaline etching solution with a low dissolved oxygen concentration to the recess 95, the sides 95s of the recess 95 can be uniformly etched from the entrance to the bottom of the recess 95. On the other hand, by supplying an alkaline etching solution with a relatively high dissolved oxygen concentration to the recess 95, the amount of etching on the sides 95s of the recess 95 increases as it approaches the bottom of the recess 95. In this case, by changing the dissolved oxygen concentration, the rate of change in the amount of etching can be increased or decreased. Therefore, by changing the dissolved oxygen concentration of the etching solution, the shape of the etched recess 95 can be controlled.

[0187] Figure 10A It is shown in Figure 8A schematic diagram of another example of the cross-section of the substrate W before the first etching solution is supplied, in one example of the processing of the substrate W shown. Figure 10B It is shown in Figure 8 A schematic diagram of another example of the cross-section of substrate W after the first etchant has been supplied, in one example of the processing of substrate W shown. Figure 10C It is shown in Figure 8 A schematic diagram of another example of the cross-section of substrate W after the second etchant has been supplied, in one example of the processing of substrate W shown.

[0188] exist Figures 10A to 10C In the example shown, polysilicon films P1 to P3, which are examples of objects to be etched 96, and silicon oxide films O1 to O3, which are examples of objects not to be etched, are exposed on the side 95s of the recess 95. The polysilicon films P1 to P3 and the silicon oxide films O1 to O3 are stacked alternately, and the recess 95 penetrates these polysilicon films P1 to P3 and silicon oxide films O1 to O3 in the thickness direction of the substrate W.

[0189] Figure 10B The cross-section of substrate W after being supplied with acidic solutions such as DHF and before being supplied with the first etchant is shown with a double-dotted line, and the cross-section of substrate W after being supplied with the first etchant is shown with a solid line. With the supply of the first etchant, the polysilicon films P1 to P3 are uniformly etched. At this time, the silicon oxide films O1 to O3 are also slightly etched.

[0190] After the first etchant is supplied to the substrate W, a second etchant, which is alkaline and has a higher dissolved oxygen concentration than the first etchant, is supplied to the substrate W. As a result, all or almost all of the first etchant in contact with the substrate W is replaced by the second etchant. Figure 10C The cross-section of the substrate W after the first etchant was supplied and before the second etchant was supplied is shown with a double-dotted line, and the cross-section of the substrate W after the second etchant was supplied is shown with a solid line.

[0191] like Figure 10C As shown, when the second etchant is supplied to the substrate W, the dissolved oxygen (O2 in Figure 9) contained in the second etchant comes into contact with the polysilicon film P1 and the silicon oxide film O1 located near the entrance of the recess 95, thereby oxidizing the polysilicon film P1. Therefore, although only slightly, the second etchant with a reduced dissolved oxygen concentration flows to the polysilicon film P2. This phenomenon repeats continuously, resulting in the dissolved oxygen concentration of the second etchant continuously decreasing as it approaches the bottom of the recess 95.

[0192] The dissolved oxygen concentration of the second etchant decreases as it approaches the bottom of the polysilicon film P3 located in the recess 95. As long as the depth-direction positions within the recess 95 are the same, the polysilicon films P1 to P3 are uniformly oxidized. However, the amount of oxidation of the polysilicon films P1 to P3 decreases as it approaches the bottom of the recess 95. When polysilicon is oxidized, it transforms into silicon oxide, which is difficult to be etched by alkaline etchants. When monocrystalline silicon and amorphous silicon are also oxidized, they transform into silicon oxide. Therefore, a comparison... Figure 10C As can be seen from the solid lines and double-dotted lines, the etching amount of polycrystalline silicon films P1 to P3 increases as the bottom of the recess 95 approaches.

[0193] Since the etching amount increases as it approaches the polysilicon film P3, even if the shape of the polysilicon films P1 to P3 when they are moved into the substrate processing apparatus 1 is different from the desired shape, the shape of the polysilicon films P1 to P3 can be changed to the desired shape or close to the desired shape after the second etching solution is supplied.

[0194] As described above, in the first embodiment, an alkaline first etching solution containing dissolved inert gas is supplied to the substrate W. As a result, the side surfaces 95s of the recess 95 formed on the substrate W are etched. Similarly, an alkaline second etching solution containing dissolved oxygen-containing gas (an example of a dissolved gas) is supplied to the substrate W. As a result, the side surfaces 95s of the recess 95 are etched. Therefore, the side surfaces 95s of the recess 95 are etched in stages by the supply of the first etching solution and the supply of the second etching solution.

[0195] The etchable object 96, representing at least one of monocrystalline silicon, polycrystalline silicon, and amorphous silicon, has at least a portion of the upper part of the side surface 95s of the recess 95 and at least a portion of the lower part of the side surface 95s of the recess 95 exposed. When a liquid with a high dissolved oxygen concentration is supplied to the etchable object 96, the surface layer of the etchable object 96 changes to silicon oxide. Silicon oxide is not etched by alkaline etching solutions or is hardly etched by alkaline etching solutions.

[0196] Dissolved oxygen present in the first etching solution is removed from the first etching solution by dissolving inactive gases. Because the dissolved oxygen concentration in the first etching solution is low, the object 96 to be etched will not be oxidized or will hardly be oxidized even when the first etching solution comes into contact with it. Therefore, by supplying the first etching solution to the substrate W, the object 96 exposed on the side 95 of the recess 95 can be etched uniformly at a high etching rate.

[0197] On the other hand, since the dissolved oxygen concentration of the second etching solution is higher than that of the first etching solution, when the second etching solution comes into contact with the object to be etched 96, the surface layer of the object to be etched 96 is oxidized, thereby transforming into silicon oxide, which is difficult to be corroded by the second etching solution. However, the entire surface area of ​​the object to be etched 96 is not uniformly oxidized, but rather unevenly oxidized.

[0198] That is, because the width W1 of the recess 95 is narrow, when the second etchant is supplied to the recess 95, the dissolved oxygen contained in the second etchant comes into contact with the object to be etched 96 near the entrance of the recess 95, thereby oxidizing the object to be etched 96. Therefore, although only slightly, the second etchant with a reduced dissolved oxygen concentration flows to the bottom of the recess 95. Even slightly away from the entrance of the recess 95, the dissolved oxygen in the second etchant comes into contact with the object to be etched 96 and is consumed. This phenomenon repeats continuously, resulting in the dissolved oxygen concentration of the second etchant decreasing as it approaches the bottom of the recess 95.

[0199] As long as the positions in the depth direction within the recess 95 are the same, the object to be etched 96 is uniformly etched by the second etching solution. However, the amount of etching of the object to be etched 96 increases as it approaches the bottom of the recess 95. That is, because the surface layer of the object to be etched 96 changes to silicon oxide near the entrance of the recess 95, the object to be etched 96 is difficult to be etched by the second etching solution. On the other hand, because the surface layer of the object to be etched 96 does not change to silicon oxide or hardly changes to silicon oxide near the bottom of the recess 95, the object to be etched 96 is etched by the second etching solution. Therefore, the amount of etching of the object to be etched near the bottom of the recess 95 is greater than the amount of etching of the object to be etched near the entrance of the recess 95.

[0200] Thus, by supplying the first etching solution to the substrate W, the object to be etched 96 exposed on the side surface of the recess 95 for 95 seconds can be uniformly etched at a high etching rate. Furthermore, by supplying the second etching solution to the substrate W, the object to be etched 96 can be etched in a manner where the etching amount increases stepwise or continuously as the bottom of the recess 95 approaches. Therefore, by supplying both the first and second etching solutions to the substrate W, it is possible to suppress the increase in processing time and intentionally achieve uneven etching of the side surface of the recess 95 for 95 seconds.

[0201] In this embodiment, a first etchant with a low dissolved oxygen concentration is supplied to the substrate W, followed by a second etchant with a relatively high dissolved oxygen concentration. When the second etchant is supplied to the substrate W first, the object to be etched, 96, exposed on the side of the recess 95 for 95 seconds, is oxidized. Therefore, when the first etchant is supplied, the object to be etched 96 is etched unevenly, and the etching rate is reduced. By supplying the first etchant first, compared to supplying the second etchant first, the processing time can be shortened, and the actual shape of the etched object 96 can be made closer to the desired shape.

[0202] In this embodiment, after the first etching solution is supplied to the substrate W, the second etching solution is supplied to the substrate W, but no liquid other than the second etching solution is supplied to the substrate W. Thus, the first etching solution in contact with the substrate W is replaced by the second etching solution. When a liquid other than the second etching solution is supplied to the substrate W before the second etching solution is supplied, the object to be etched 96 exposed on the side 95S of the recess 95 may be oxidized into an undesirable shape. By replacing the first etching solution in contact with the substrate W with the second etching solution, this oxidation can be suppressed or prevented, thereby enabling high-precision etching of the object to be etched 96.

[0203] In this embodiment, the recess 95, which tapers as it approaches the bottom, is etched using a first etching solution and a second etching solution. During the supply of the first etching solution, the object 96 exposed on the side 95s of the recess 95 is uniformly etched. During the supply of the second etching solution, the amount of etching of the object 96 increases as it approaches the bottom of the recess 95. After supplying the first and second etching solutions, the width W1 of the recess 95 becomes uniform from the entrance to the bottom of the recess 95, or any unevenness in the width W1 of the recess 95 is reduced. Therefore, if the width W1 of the recess 95 is uneven before etching, the shape of the recess 95 can be adjusted.

[0204] Polycrystalline silicon is composed of multiple monocrystalline silicon crystals. When polycrystalline silicon is etched with an alkaline etchant that does not contain compounds, very fine unevenness is formed on the surface of the polycrystalline silicon. This is because the (110), (100), and (111) planes of silicon are exposed on the surface of the polycrystalline silicon, and the etching rates of the (110), (100), and (111) planes of silicon are different from each other. In the case of etching monocrystalline silicon, for the same reason, very fine unevenness is formed on the surface of the monocrystalline silicon.

[0205] In an alkaline etching solution, hydroxide ions (OH) react with silicon (Si), thereby etching the polycrystalline silicon and other etchable objects 96. When a compound is added to the alkaline etching solution, it hinders the contact between hydroxide ions and silicon, reducing the etching rate of the (110), (100), and (111) planes of silicon. However, the etching rate does not decrease uniformly across the multiple crystal planes, but rather decreases significantly at the crystal planes with high etching rates. Consequently, the difference in etching rates across the multiple crystal planes decreases.

[0206] Thus, by adding a compound to the alkaline etching solution, the anisotropy of the etching solution for the etched object 96, such as polycrystalline silicon, is reduced. That is, the etching of the etched object 96 approaches isotropic etching, and the etched object 96 is etched with a uniform etching amount regardless of any part. As a result, the planar orientation dependence of the etching rate is mitigated. Therefore, the generation of the aforementioned unevenness can be suppressed or prevented, thereby enabling the surface of the etched object 96 to be flattened after etching.

[0207] Next, the second embodiment will be described.

[0208] The main difference between the second embodiment and the first embodiment is that the substrate processing apparatus 101 is a batch-type apparatus for processing multiple substrates W at the same time.

[0209] Figure 11 This is a schematic diagram showing the etching unit 104 included in the substrate processing apparatus 101 according to the second embodiment of the present invention. Figure 11 In the middle, regarding the above Figures 1 to 1... Figure 10C The structures shown are equivalent to those in Figure 1, and the descriptions are omitted.

[0210] The substrate processing apparatus 101 includes: multiple processing units for processing multiple substrates W simultaneously; a transport unit for transporting the multiple substrates W into the processing units and removing the multiple substrates W from the processing units; and a control device 3 for controlling the substrate processing apparatus 101. The multiple processing units include an etching unit 104 that simultaneously supplies etching solution to the multiple substrates W. Although not shown, the multiple processing units also include: a rinsing solution processing unit that simultaneously supplies rinsing solution to the multiple substrates W to which the etching solution is supplied; and a drying processing unit that simultaneously dries the multiple substrates W to which the rinsing solution is supplied.

[0211] The etching unit 104 includes an immersion tank 105 for storing etching solution and simultaneously transporting multiple substrates W. The transport unit includes: a holder 103 for holding multiple substrates W in a vertical position; and a lift 102 for moving the holder 103 between a lower position and an upper position, wherein the lower position is the position where the multiple substrates W held by the holder 103 are immersed in the etching solution in the immersion tank 105, and the upper position is the position where the multiple substrates W held by the holder 103 are above the etching solution in the immersion tank 105.

[0212] The etching unit 104 further includes: a plurality of etching solution nozzles 106, each having an etching solution outlet for ejecting etching solution; and a plurality of gas nozzles 114, each having a gas outlet for ejecting inactive gas. The etching solution nozzles 106 and gas nozzles 114 are cylindrical, extending horizontally within the immersion tank 105. The plurality of etching solution nozzles 106 and gas nozzles 114 are arranged parallel to each other in a horizontal orientation. One or more gas nozzles 114 are arranged between two adjacent etching solution nozzles 106. The retainer 103 is positioned in the lower position (…). Figure 11 When the position shown is such that multiple etchant nozzles 106 and multiple gas nozzles 114 are arranged below the multiple substrates W held by the holder 103.

[0213] Etching solution piping 107 is connected to a plurality of etching solution nozzles 106. Etching solution piping 107 includes: a common piping 107c for guiding the etching solution supplied to the plurality of etching solution nozzles 106; and a plurality of branch piping 107d for supplying the etching solution supplied from the common piping 107c to the plurality of etching solution nozzles 106. The common piping 107c is connected to a mixing valve 80. An etching solution valve 108 is installed on the common piping 107c. The plurality of branch piping 107d branches from the common piping 107c. The plurality of branch piping 107d are respectively connected to the plurality of etching solution nozzles 106. Figure 11 Although it is described that only the two etchant nozzles 106 on both sides are connected to the branch pipes 107d, the other etchant nozzles 106 are also connected to the branch pipes 107d.

[0214] Gas piping 115 is connected to a plurality of gas nozzles 114. Gas piping 115 includes: a common piping 115c for guiding gas supplied to the plurality of gas nozzles 114; and a plurality of branch piping 115d for supplying gas from the common piping 115c to the plurality of gas nozzles 114. The common piping 115c is connected to an inactive gas supply source. Gas valve 116 and flow regulating valve 117 are mounted on the common piping 115c. The plurality of branch piping 115d branches from the common piping 115c. The plurality of branch piping 115d are each connected to a plurality of gas nozzles 114. Figure 11Although it is described that only the two gas nozzles 114 on both sides are connected to the branch control pipes 115d, the other gas nozzles 114 are also connected to the branch control pipes 115d.

[0215] The etching unit 104 includes an overflow tank 113 to catch the etching solution overflowing from the immersion tank 105. The upstream end of a return pipe 112 is connected to the overflow tank 113, and the downstream end of the return pipe 112 is connected to a common pipe 107c of the etching solution pipe 107 downstream of the etching solution valve 108. The etching solution overflowing from the immersion tank 105 into the overflow tank 113 is pumped again by a pump 109 to a plurality of etching solution nozzles 106 and filtered by a filter 111 before reaching the plurality of etching solution nozzles 106. The etching unit 104 may also include a temperature regulator 110 that changes the temperature of the etching solution in the immersion tank 105 by heating or cooling the etching solution.

[0216] When the etching solution is ejected from the multiple etching nozzles 106, the etching solution is supplied to the immersion tank 105, and an upward flow of etching solution is formed in the immersion tank 105. The etching solution overflowing from the opening at the upper end of the immersion tank 105 is caught by the overflow tank 113 and returned to the multiple etching nozzles 106 via the return pipe 112. Thus, the etching solution is circulated. On the other hand, when the drain valve 119 installed in the drain pipe 118 is opened, the liquid in the immersion tank 105, such as the etching solution, is discharged into the drain pipe 118.

[0217] When a first etchant and a second etchant, both with different dissolved oxygen concentrations, are supplied to multiple substrates W held by a holder 103, the first etchant is supplied to the immersion tank 105 via multiple etchant nozzles 106 with the drain valve 119 closed. After a predetermined time has elapsed since the first etchant supply began, the drain valve 119 is opened to drain the first etchant from the immersion tank 105. Then, with the drain valve 119 closed, the second etchant is supplied to the immersion tank 105 via the multiple etchant nozzles 106.

[0218] The first etchant and the second etchant can also be mixed in the immersion tank 105. For example, the supply of the first etchant can be stopped after a predetermined time has elapsed, and then the supply of the second etchant can be started. In this case, the first etchant and the second etchant are mixed together in the immersion tank 105, thereby changing the dissolved oxygen concentration of the etchant supplied to the substrate W.

[0219] Instead of sequentially supplying the first and second etchants to a single immersion tank 105, it is possible to provide an immersion tank 105 containing the first etchant and an immersion tank 105 containing the second etchant, and then sequentially transfer multiple substrates W to form a batch into the two immersion tanks 105. This eliminates the need for replacing the etchant in the immersion tank 105 with the second etchant.

[0220] Other implementation methods

[0221] This invention is not limited to the above-described embodiments, and various modifications can be made.

[0222] For example, in the first embodiment, the etching solution may be supplied to the lower surface of the substrate W instead of the upper surface of the substrate W. Alternatively, the etching solution may be supplied to both the upper and lower surfaces of the substrate W. In these cases, it is sufficient to simply eject the etching solution from the lower surface nozzle 15.

[0223] In the first embodiment, the first etchant and the second etchant may be ejected from each nozzle. Alternatively, at least two of the undiluted etchant, the first diluent, and the second diluent may be ejected from each nozzle, thereby mixing in the space between the upper surface of the substrate W and the nozzle.

[0224] In the first embodiment, a first etching solution tank for storing a first etching solution and a second etching solution tank for storing a second etching solution may also be provided. In this case, the first etching solution and the second etching solution may be sprayed from the same nozzle toward the substrate W, or they may be sprayed from different nozzles toward the substrate W.

[0225] In the first embodiment, instead of replacing the first etchant on the substrate W with the second etchant, the first etchant on the substrate W may be replaced with a liquid other than the second etchant (an intermediate liquid), and then the intermediate liquid on the substrate W may be replaced with the second etchant. Alternatively, two or more types of liquids may be supplied to the substrate W sequentially between the supply of the first etchant and the supply of the second etchant. For example, the first etchant on the substrate W may be replaced with a first intermediate liquid, the first intermediate liquid on the substrate W may be replaced with a second intermediate liquid, and the second intermediate liquid on the substrate W may be replaced with the second etchant.

[0226] In both the first and second embodiments, the second etchant may be supplied to the substrate W before the first etchant is supplied to the substrate W. In this case, the second and first etchants may be supplied to the substrate W continuously, or a liquid other than the first etchant may be supplied to the substrate W before the first etchant is supplied.

[0227] In both the first and second embodiments, the compounds contained in the first etching solution may differ from those contained in the second etching solution.

[0228] In both the first and second embodiments, at least one of the first and second etching solutions may be an alkaline etching solution that does not contain the aforementioned compound. In this case, the aforementioned compound may be mixed with the etching solution before or after the alkaline etching solution that does not contain the compound is supplied to the substrate W. For example, the alkaline etching solution that does not contain the compound may be mixed with a compound-containing liquid on the surface or back side of the substrate W.

[0229] The cylindrical part 37 can also be omitted from the blocking member 33. The upper support part 43 and the lower support part 44 can also be omitted from the blocking member 33 and the rotating chuck 10.

[0230] Alternatively, the blocking member 33 can be omitted from the processing unit 2. In this case, it is sufficient to provide a nozzle in the processing unit 2 for spraying a processing liquid such as a medicinal liquid toward the substrate W. The nozzle can be a scanning nozzle that can move horizontally within the chamber 4, or a fixed nozzle that is fixed to the partition wall 6 of the chamber 4. The nozzle can also have multiple liquid outlets, which simultaneously spray the processing liquid toward multiple positions radially separated on the substrate W, thereby supplying the processing liquid to the upper or lower surface of the substrate W. In this case, at least one of the flow rate, temperature, and concentration of the sprayed processing liquid can be varied for each liquid outlet.

[0231] The substrate processing apparatus 1 is not limited to an apparatus for processing a circular substrate W, but may also be an apparatus for processing a polygonal substrate W.

[0232] Two or more of the above structures can also be combined. Two or more of the above processes can also be combined.

[0233] Although embodiments of the present invention have been described in detail, these embodiments are merely specific examples used to illustrate the technical content of the present invention, and the present invention should not be construed as being limited to these specific examples. The present invention is defined only by the appended claims.

[0234] Explanation of reference numerals in the attached figures:

[0235] 1: Substrate processing device

[0236] 61: Processing liquid supply unit (first etching unit and second etching unit)

[0237] 95: Concave

[0238] 95s: Side of the concave part

[0239] 96: Etched object

[0240] D1: Depth of the recess

[0241] W: substrate

[0242] W1: Width of the recess

Claims

1. A substrate processing method comprising processing a substrate having a recess formed thereon, the width of the recess being shorter than its depth, and exposing an etched object representing at least one of monocrystalline silicon, polycrystalline silicon, and amorphous silicon at least a portion of the upper part and at least a portion of the lower part of the side surface of the recess, wherein, The substrate processing method includes: The first etching step involves supplying an alkaline first etching solution containing dissolved inert gases to the substrate to etch the object to be etched exposed on the side of the recess; and The second etching process involves supplying a second, alkaline etching solution containing dissolved gases and having a higher dissolved oxygen concentration than the first etching solution to the substrate, thereby etching the object exposed on the side of the recess. The width of the recess before the first and second etchants are supplied decreases as it approaches the bottom of the recess; The second etching process is as follows: the side surface of the recess is etched in such a way that the amount of etching on the side surface of the recess increases as it approaches the bottom of the recess.

2. The substrate processing method as described in claim 1, wherein, The second etching process is as follows: after supplying the first etching solution to the substrate, the second etching solution is supplied to the substrate.

3. The substrate processing method as described in claim 2, wherein, The second etching process includes the following steps: supplying the second etching solution to the substrate, thereby replacing the first etching solution in contact with the substrate with the second etching solution.

4. The substrate processing method according to any one of claims 1 to 3, wherein, At least one of the first etching solution and the second etching solution is an alkaline etching solution comprising a compound for preventing hydroxide ions from contacting the object being etched.

5. The substrate processing method as described in claim 4, wherein, The concentration of the compound in the alkaline etching solution is set according to the required etching uniformity and the required etching rate.

6. The substrate processing method according to any one of claims 1 to 3, wherein, The first etching step includes a first etching solution preparation step, which involves diluting the stock solution of the alkaline etching solution with at least one of a first diluent and a second diluent of different dissolved oxygen concentrations to prepare the first etching solution. The second etching process includes a second etching solution preparation process, which involves diluting the stock solution by at least one of the first diluent and the second diluent to prepare the second etching solution.

7. The substrate processing method according to any one of claims 1 to 3, wherein, In the substrate processing method, multiple substrates are processed one by one.

8. The substrate processing method according to any one of claims 1 to 3, wherein, In the substrate processing method, multiple substrates are processed simultaneously.

9. A substrate processing apparatus for processing a substrate having a recess formed thereon, the width of the recess being shorter than its depth, and at least a portion of the upper part of a side surface of the recess and at least a portion of the lower part of the side surface exposing an etched object representing at least one of monocrystalline silicon, polycrystalline silicon, and amorphous silicon. The substrate processing apparatus includes: The first etching unit etches the object to be etched on the side of the recess by supplying an alkaline first etching solution containing dissolved inert gas to the substrate. as well as The second etching unit etches the object exposed on the side of the recess by supplying a second alkaline etching solution containing dissolved gases and having a higher dissolved oxygen concentration than the first etching solution to the substrate. The width of the recess before the first and second etchants are supplied decreases as it approaches the bottom of the recess; The second etching unit etches the side surface of the recess in such a manner that the amount of etching on the side surface of the recess increases as it approaches the bottom of the recess.

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