Substrate processing method and substrate processing apparatus

Abstract

Etching is performed on an etching object indicating at least one of single crystal silicon and polycrystal silicon by supplying a basic first etching liquid to a substrate. Before or after the first etching liquid is supplied to the substrate, etching is performed on the etching object by supplying a basic second etching liquid to the substrate, the second etching liquid containing a compound that prevents hydroxide ions from coming into contact with the etching object, and the difference between the maximum and minimum values of the etching rate for the (110) surface, the (100) surface, and the (111) surface of silicon is smaller than that of the first etching liquid, and the maximum value of the etching rate is smaller than that of the first etching liquid.

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2020-146097, filed on August 31, 2020, and incorporates the entire contents of that application.

[0002] This invention relates to a substrate processing method and a substrate processing apparatus for processing substrates. Substrates include, 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, substrates for solar cells, etc. Background Technology

[0003] In the manufacturing processes of semiconductor devices, FPDs, etc., 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. If a single-crystal silicon is etched using an alkaline etching solution, the etching rate will vary on each crystal plane of the silicon. Patent Document 1 discloses that, in order to mitigate the face orientation dependence of the etching rate, TMAH containing propylene glycol is supplied to the substrate.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-038956 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] If TMAH containing propylene glycol is supplied to the substrate as described in Patent Document 1, while this reduces the anisotropy of the etching, it also leads to a decrease in the etching rate (the amount of material etched per unit time), thus increasing the processing time. While acidic etchants such as a mixture of hydrofluoric acid and nitric acid can achieve uniform etching of the target material in a short time, depending on the substrate condition, there are cases where alkaline etchants are preferred. For example, in selective etching where etching of non-target materials such as silicon oxide and silicon nitride is suppressed while etching of target materials such as monocrystalline silicon and polycrystalline silicon is performed, a high selectivity cannot be obtained without using an alkaline etchant.

[0009] Therefore, one of the objectives of the present invention is to provide a substrate processing method and substrate processing apparatus that can shorten processing time and uniformly etch an object representing at least one of monocrystalline silicon or polycrystalline silicon.

[0010] means for solving problems

[0011] An embodiment of the present invention provides a substrate processing method for processing a substrate containing an etchable object representing at least one of monocrystalline silicon and polycrystalline silicon; the method includes a first etching step and a second etching step; the first etching step etches the etchable object by supplying an alkaline first etching solution to the substrate; the second etching step etches the etchable object by supplying an alkaline second etching solution to the substrate before or after supplying the first etching solution to the substrate; the second etching solution contains a compound that hinders the contact between hydroxide ions and the etchable object, and the difference between the maximum and minimum etching rates of the (110), (100), and (111) surfaces of silicon is smaller than that of the first etching solution, and the maximum value of the etching rate is smaller than that of the first etching solution.

[0012] In this method, an alkaline first etchant is supplied to a substrate exposing at least one of monocrystalline silicon and polycrystalline silicon as the object to be etched. This etches the object. Then, before or after the first etchant is supplied to the substrate, an alkaline second etchant is supplied to the substrate. This further etches the object.

[0013] The second etchant is a liquid containing a compound that hinders the contact between hydroxide ions and the object being etched. This compound causes variations in etching anisotropy and etching rate. Specifically, the difference between the maximum and minimum etching rates of the second etchant on the (110), (100), and (111) planes of silicon is smaller than that of the first etchant. That is, the etching anisotropy of the second etchant is smaller than that of the first etchant. In addition, the maximum etching rate of the second etchant on these crystalline planes is smaller than that of the first etchant.

[0014] If the first etchant is supplied to the substrate, although the etching uniformity is worse than that of the second etchant, the object to be etched will be etched at a higher speed. If the second etchant is supplied to the substrate, although the etching is slower than that of the first etchant, the object to be etched can be etched uniformly. Therefore, by supplying the first and second etchants, which have different etching anisotropy and etching rates, to the substrate, the processing time can be shortened and the object to be etched can be etched uniformly compared to the case of continuously supplying the second etchant.

[0015] In the above embodiments, at least one of the following features may also be added to the above substrate processing method.

[0016] The second etching step includes the step of replacing the first etching solution that is in contact with the substrate with the second etching solution by supplying the second etching solution to the substrate.

[0017] In this method, after the first etchant is supplied to the substrate, instead of supplying a liquid other than the second etchant, the second etchant is supplied to the substrate. This replaces the first etchant in contact with the substrate with the second etchant. If the object to be etched is oxidized, its surface layer will change to silicon oxide. Silicon oxide is not etched by alkaline etchants, or is hardly etched at all.

[0018] If the second etchant is supplied to the substrate immediately after the first etchant is supplied, the time from the supply of the first etchant to the supply of the second etchant can be shortened, thus suppressing or preventing oxidation of the etched object. Therefore, compared to the case of continuously supplying the second etchant, the processing time can be shortened, and the actual shape of the etched object can be closer to the desired shape.

[0019] The first etching solution is an alkaline etching solution containing the above-mentioned compound, and the first etching solution and the second etching solution are different from each other in at least one of the following: composition, concentration and temperature.

[0020] In this method, not only the second etchant but also the first etchant contains compounds. Therefore, the first etchant also reduces the anisotropy of the etching process. The first and second etchants differ from each other in at least one of their composition, concentration, and temperature. If at least one of these differs, the anisotropy of the etching and the etching rate will change. Thus, compared to a continuously supplied second etchant, the processing time can be shortened, and the object being etched can be etched more uniformly.

[0021] When the alkaline etching solution containing the compound is a solution containing the etching substance, the compound, and the solvent, the first etching solution and the second etching solution may differ in the type of at least one of the etching substance and the compound, or at least one of the first etching solution and the second etching solution may contain substances other than the etching substance, the compound, and the solvent. The first etching solution and the second etching solution may differ in the concentration of the etching substance or the compound, or both the concentration of the etching substance and the compound may differ.

[0022] The second etching step described above includes at least one of the following steps: mixing the compound into the first etching solution that is in contact with the substrate; and mixing the first etching solution into the compound-containing solution while the substrate is in contact with the compound-containing solution.

[0023] In this method, after the first etchant is supplied to the substrate, a compound is then supplied to the substrate. Thus, the compound is mixed into the first etchant in contact with the substrate, and the first etchant containing the compound is supplied to the substrate as the second etchant. Alternatively, a compound-containing solution is supplied to the substrate, and then the first etchant is supplied to the substrate. Thus, the first etchant is mixed into the compound-containing solution in contact with the substrate, and the mixture of the compound-containing solution and the first etchant is supplied to the substrate as the second etchant. If the first etchant is continuously supplied, the compound-containing solution will disappear from the vicinity of the substrate, and only the first etchant is supplied to the substrate. In this way, because the second etchant is prepared using the first etchant, the amount of etchant used can be reduced.

[0024] This includes repeating a cycle that includes the first etching step and the second etching step described above multiple times.

[0025] In this method, the first etchant and the second etchant are alternately supplied to the substrate multiple times. If the first etchant, which has a greater anisotropy, is continuously supplied to the substrate, the area of ​​the exposed portion of the (111) surface, which has a lower etching rate, will increase. In this case, because the contact area between the crystal surfaces other than the (111) surface and the first etchant is reduced, the etching rate decreases. If the second etchant, which has a smaller anisotropy, is supplied, the (111) surface will be etched, and the area of ​​the exposed portion of the crystal surface will decrease. Then, if the first etchant is supplied to the substrate, the substrate can be etched again at a higher etching rate.

[0026] Another embodiment of the present invention provides a substrate processing apparatus for processing a substrate containing an etchable object representing at least one of monocrystalline silicon and polycrystalline silicon. The apparatus includes a substrate holding unit, a first etching unit, and a second etching unit. The substrate holding unit holds the substrate. The first etching unit etches the etchable object by supplying an alkaline first etching solution to the substrate held by the substrate holding unit. The second etching unit etches the etchable object by supplying an alkaline second etching solution to the substrate held by the substrate holding unit before or after supplying the first etching solution to the substrate. The second etching solution contains a compound that inhibits the contact between hydroxide ions and the etchable object. The difference between the maximum and minimum etching rates of the (110), (100), and (111) surfaces of silicon is smaller than that of the first etching solution, and the maximum etching rate is smaller than that of the first etching solution. With this configuration, the same effect as the aforementioned substrate processing method can be achieved.

[0027] The foregoing or other objects, features and effects of the present invention will become clear from the accompanying drawings and the following description of the embodiments. Attached Figure Description

[0028] Figure 1A This is a schematic diagram of the substrate processing apparatus according to the first embodiment of the present invention, viewed from above.

[0029] Figure 1B This is a schematic diagram of the substrate processing device viewed from the side.

[0030] Figure 2 This is a schematic diagram of the interior of the processing unit in a horizontally inspected substrate processing device.

[0031] Figure 3 It is magnification Figure 2 A magnified view of a portion of it.

[0032] Figure 4 This is an example graph showing the relationship between the etching rate of the three crystal planes of silicon and the concentration of propylene glycol in the etching solution.

[0033] Figure 5A This is a diagram used to illustrate the hypothetical mechanism when the contact between hydroxide ions and polycrystalline silicon is hindered by a barrier substance.

[0034] Figure 5B This is a diagram used to illustrate the hypothetical mechanism when the contact between hydroxide ions and polycrystalline silicon is hindered by a barrier substance.

[0035] Figure 6 This is a schematic diagram of a processing liquid supply unit in a substrate processing apparatus that supplies processing liquids such as etching solutions to a substrate.

[0036] Figure 7 This is a block diagram showing the electrical configuration of the substrate processing device.

[0037] Figure 8 This is a step diagram illustrating an example of substrate processing performed using a substrate processing apparatus.

[0038] Figure 9A It means in Figure 8 A schematic diagram of a cross-section of the substrate after the first etching solution has been supplied in one example of substrate processing shown.

[0039] Figure 9B It means in Figure 8 A schematic diagram of a cross-section of the substrate after the second etching solution has been supplied in one example of substrate processing shown.

[0040] Figure 10 It means in Figure 8 A graph illustrating the relationship between processing time and etching rate when the first etchant and the second etchant are supplied alternately multiple times in one example of substrate processing.

[0041] Figure 11This is a schematic diagram showing the cross-section of a silicon fin after it has been etched using an etchant that does not contain compounds.

[0042] Figure 12 It means in Figure 8 The schematic diagram shows a cross-section of a silicon fin after alternating supply of a first etchant and a second etchant to etch it, as shown in an example of substrate processing.

[0043] Figure 13 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

[0044] Figure 1A This 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 device 1 viewed from the side.

[0045] like Figure 1A As shown, the substrate processing apparatus 1 is a single-sheet device that processes wafer-shaped substrates W one by one, such as semiconductor wafers. The substrate processing apparatus 1 includes a load port LP, multiple processing units 2, a transfer robot, and a control device 3. The load port LP holds a container C for accommodating the substrates W. The multiple processing units 2 process the substrates W transferred from the container C on the load port LP. The transfer robot transfers the substrates W between the container C on the load port LP and the processing units 2. The control device 3 controls the substrate processing apparatus 1.

[0046] The transport robot includes: an indexing robot IR that moves substrate W into and out of a container C on a loading port LP; and a central robot CR that moves substrate W into and out of multiple processing units 2. The indexing robot IR moves substrate W between the loading port LP and the central robot CR, and the central robot CR moves substrate W between the indexing robot IR and the processing units 2. The central robot CR has a hand H1 that supports substrate W, and the indexing robot IR has a hand H2 that supports substrate W.

[0047] Multiple processing units 2 are formed in multiple towers TW arranged around the central robot arm CR in a top view. Figure 1A This example illustrates the formation of four tower TWs. The central robotic arm CR can access any of the tower TWs. For example... Figure 1B As shown, each tower TW has multiple (e.g., 3) processing units 2 stacked on top of each other.

[0048] Figure 2 This is a schematic diagram of the interior of the processing unit 2 included in the horizontal observation substrate processing device 1. Figure 3 It is Figure 2One of the enlarged images. Figure 2 This indicates that the lifting frame 32 and the barrier component 33 are in the lower position. Figure 3 This indicates that the lifting frame 32 and the barrier member 33 are in the upper position. In the following description, unless otherwise stated, TMAH refers to an aqueous solution of TMAH.

[0049] The processing unit 2 includes a box-shaped chamber 4, a rotary chuck 10, and a cylindrical processing cup 23. The box-shaped chamber 4 has an internal space. The rotary chuck 10 holds a substrate W horizontally within the chamber 4 while rotating about a vertical rotation axis A1 passing through the center of the substrate W. The cylindrical processing cup 23 surrounds the rotary chuck 10 about the rotation axis A1.

[0050] The chamber 4 includes a box-shaped partition 6 and a gate 7. The box-shaped partition 6 has an inlet / outlet 6b for the substrate W to pass through, and the gate 7 opens and closes the inlet / outlet 6b. The chamber 4 further includes a rectifier plate 8 disposed below an air inlet 6a that is open on the top surface of the partition 6. An FFU5 (fan filter unit) for supplying clean air (air filtered by a filter) is disposed on the air inlet 6a. An exhaust duct 9 for discharging gas from the chamber 4 is connected to the processing cup 23. The air inlet 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 is disposed outside the chamber 4.

[0051] 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 ground 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 ground 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.

[0052] 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 rectifier plate 8 through multiple through holes running vertically through it. The 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 downward flow of clean air from the rectifier plate 8 is formed in the lower space SL. The processing of the substrate W is performed while the downward flow of clean air is forming.

[0053] The rotary chuck 10 includes a circular plate-shaped rotating base 12 held in a horizontal position, a plurality of chuck pins 11 holding the substrate W in a horizontal position above the rotating base 12, a rotating shaft 13 extending downward from the center of the rotating base 12, and a rotary motor 14 that rotates the rotating base 12 and the plurality of chuck pins 11 by rotating the rotating 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 may also be a vacuum chuck that holds the substrate W horizontally by adsorbing the back side (lower surface) of the substrate W (non-device forming surface) onto the upper surface 12u of the rotating base 12.

[0054] 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 facing the lower surface of the substrate W. The upper surface 12u of the rotating base 12 is annular in shape surrounding the rotation axis A1. The outer diameter of the upper surface 12u of the rotating base 12 is larger than the outer diameter of the substrate W. 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 with the lower surface of the substrate W away from the upper surface 12u of the rotating base 12.

[0055] The processing unit 2 includes a lower surface nozzle 15 that 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 spray outlet 15p of the lower surface nozzle 15 opens at the center of the upper part of the nozzle circular plate portion. When the substrate W is held by the rotating chuck 10, the liquid spray outlet 15p of the lower surface nozzle 15 faces the center of the lower surface of the substrate W vertically.

[0056] The substrate processing apparatus 1 includes a lower rinsing fluid pipe 16 that guides rinsing fluid to a lower surface nozzle 15, and a lower rinsing fluid valve 17 installed in the lower rinsing fluid pipe 16. When the lower rinsing fluid valve 17 is opened, the rinsing fluid guided by the lower rinsing fluid pipe 16 is sprayed upwards from the lower surface nozzle 15 and supplied to the central portion of the lower surface of the substrate W. The rinsing fluid supplied to the lower surface nozzle 15 is pure water (deionized water). The rinsing fluid supplied to the lower surface nozzle 15 is not limited to pure water; it can also be any of IPA (isopropanol), carbonated water, electrolyzed ionized water, hydrogen water, ozone water, and hydrochloric acid water with a diluted concentration (e.g., approximately 1–100 ppm).

[0057] Although not shown in the figure, the downflushing fluid valve 17 includes: a valve body having an internal flow path for liquid flow and an annular valve seat surrounding the internal flow path; a valve core movable relative to the valve seat; and an actuator that moves the valve core between a closed position where the valve core contacts the valve seat and an open position where the valve core moves away from the valve seat. Other valves are similar. 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 fluid valve 17.

[0058] 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 in the lower gas pipe 20; and a lower gas flow rate regulating valve 22 for changing the flow rate of inactive gas supplied from the lower gas pipe 20 to the lower cylindrical passage 19.

[0059] 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 and argon. These inert gases are low-oxygen gases with an oxygen concentration lower than that in air (approximately 21 vol%).

[0060] When the lower gas valve 21 is opened, nitrogen gas supplied from the lower gas pipe 20 to the lower cylindrical passage 19 at a flow rate corresponding to the opening of the lower gas flow rate regulating valve 22 is ejected upwards from the lower central opening 18. Then, 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. As a result, 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 rate regulating valve 22. The lower gas valve 21 and the lower gas flow rate regulating valve 22 are included in an ambient gas oxygen concentration changing unit that changes the oxygen concentration in the ambient gas in contact with the substrate W.

[0061] The processing cup 23 includes: a plurality of protective covers 25 for receiving liquid discharged outward from the substrate W, a plurality of cups 26 for receiving liquid guided downward by the plurality of protective covers 25, and a cylindrical outer wall member 24 surrounding the plurality of protective covers 25 and the plurality of cups 26. Figure 2 This example shows a structure with two protective shields 25 and two cups 26.

[0062] The protective cover 25 includes: a cylindrical protective cover portion 25b surrounding the rotating chuck 10, and an annular protective cover top plate portion 25a extending obliquely upward from the upper end of the protective cover cylindrical portion 25b toward the rotation axis A1. Multiple protective cover top plates 25a overlap vertically, and multiple protective cover cylindrical portions 25b are arranged concentrically. Multiple cups 26 are respectively disposed below the multiple protective cover cylindrical portions 25b. The cups 26 form annular liquid receiving grooves with upward openings.

[0063] Processing unit 2 includes a protective cover lifting unit 27 that 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 between an upper position and a lower position. The upper position is a position where the upper end 25u of the protective cover 25 is higher than the holding position of the substrate W held by the rotating chuck 10. The lower position is a position where the upper end 25u of the protective cover 25 is lower than the holding position. The annular upper end of the protective cover top plate portion 25a corresponds to the upper end 25u of the protective cover 25. Viewed from above, the upper end 25u of the protective cover 25 surrounds the substrate W and the rotating base 12.

[0064] If the processing liquid is supplied to the substrate W while the substrate W is rotated by the rotating chuck 10, the processing liquid supplied to the substrate W will be thrown off the substrate W. When the processing liquid is supplied to the substrate W, the upper end 25u of at least one protective cover 25 is positioned above the substrate W. Therefore, the processing liquid, such as medicine and rinsing liquid, discharged from the substrate W can be received by a protective cover 25 and guided into the cup 26 corresponding to that protective cover 25.

[0065] like Figure 3 As shown, the processing unit 2 includes: a lifting frame 32 disposed above the rotary chuck 10, a barrier member 33 suspended from the lifting frame 32, a central nozzle 45 inserted into the barrier member 33, and a barrier member lifting unit 31 that raises and lowers the barrier member 33 and the central nozzle 45 by raising and lowering the lifting frame 32. The lifting frame 32, the barrier member 33, and the central nozzle 45 are disposed below the rectifier plate 8.

[0066] The barrier 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 barrier member 33 includes an upwardly recessed cup-shaped inner surface. The inner surface of the barrier 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 is also referred to as "the lower surface 36L of the barrier member 33".

[0067] The lower surface 36L of the circular plate portion 36 is an opposing surface facing 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 peripheral edge of the lower surface 36L of the circular plate portion 36. The inner diameter of the cylindrical portion 37 gradually increases as it approaches the lower end of the inner peripheral surface 37i of the cylindrical portion 37. The inner diameter of 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 of 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. If the blocking member 33 is disposed in the lower position described later ( Figure 2 (As shown in the figure), the substrate W is surrounded by the inner peripheral surface 37i of the cylindrical portion 37.

[0068] The lower surface 36L of the circular plate portion 36 is annular, surrounding the rotation axis A1. The inner periphery of the lower surface 36L of the circular plate portion 36 forms an upper central opening 38 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 penetrates the blocking member 33 vertically. 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.

[0069] The inner circumferential surface of the barrier member 33 is coaxial with the outer circumferential surface of the central nozzle 45. The inner circumferential surface of the barrier 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 barrier member 33 and the outer circumferential surface of the central nozzle 45 form an upwardly extending cylindrical passage 39. The central nozzle 45 protrudes upward from the lifting frame 32 and the barrier member 33. When the barrier 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 pharmaceuticals and rinsing solutions are sprayed downward from the lower end of the central nozzle 45.

[0070] The barrier 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 both the circular plate portion 36 and the cylindrical portion 37 of the barrier 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.

[0071] The lifting frame 32 includes: an upper plate 32u located above the flange portion 34 of the blocking member 33; a side ring 32s extending downward from the upper plate 32u and surrounding the flange portion 34; and an annular lower plate 32L extending inward from the lower end of the side ring 32s and located below the flange portion 34 of the blocking member 33. The outer periphery of the flange portion 34 is disposed between the upper plate 32u and the lower plate 32L. The outer periphery of the flange portion 34 can move up and down between the upper plate 32u and the lower plate 32L.

[0072] The lifting frame 32 and the blocking member 33 include: a positioning protrusion 41 and a positioning hole 42 that 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 This example shows a plurality of positioning protrusions 41 disposed on the lower plate 32L, and a plurality of positioning holes 42 disposed on the flange portion 34. Alternatively, the positioning protrusions 41 may be disposed on the flange portion 34, and the positioning holes 42 may be disposed on the lower plate 32L.

[0073] Multiple positioning protrusions 41 are arranged on a circle centered on the rotation axis A1. Similarly, multiple positioning holes 42 are arranged on a circle centered on the rotation axis A1. The multiple positioning holes 42, like the multiple positioning protrusions 41, are arranged regularly in the circumferential direction. The positioning protrusions 41, protruding upward from the upper surface of the lower plate 32L, are inserted into the positioning holes 42 extending upward from the lower surface of the flange portion 34. This restricts the circumferential movement of the blocking member 33 relative to the lifting frame 32.

[0074] The barrier member 33 includes a plurality of upper support portions 43 protruding downward from the inner surface of the barrier member 33. The rotary chuck 10 includes a plurality of lower support portions 44, each supporting one of the upper support portions 43. The plurality of upper support portions 43 are surrounded by the cylindrical portion 37 of the barrier 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.

[0075] 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 regularly in the circumferential direction, just like 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. If the rotating base 12 is positioned at a reference rotation angle, then in top view, the multiple upper support portions 43 overlap the multiple lower support portions 44 respectively.

[0076] The barrier member lifting unit 31 is connected to the lifting frame 32. When the flange 34 of the barrier member 33 is supported by the lower plate 32L of the lifting frame 32, if the barrier member lifting unit 31 lowers the lifting frame 32, the barrier member 33 will also lower. When the rotating base 12 is positioned such that, in plan view, the multiple upper support portions 43 overlap the multiple lower support portions 44 at a reference rotation angle, if the barrier member lifting unit 31 lowers the barrier member 33, the lower end of the upper support portion 43 will contact the upper end of the lower support portion 44. Thus, the multiple upper support portions 43 are each supported by the multiple lower support portions 44.

[0077] After the upper support portion 43 of the barrier member 33 contacts the lower support portion 44 of the rotary chuck 10, if the barrier member lifting unit 31 lowers the lifting frame 32, the lower plate 32L of the lifting frame 32 moves downward relative to the flange portion 34 of the barrier member 33. As a result, the lower plate 32L moves away from the flange portion 34, and the positioning protrusion 41 is pulled out of the positioning hole 42. Furthermore, because the lifting frame 32 and the central nozzle 45 move downward relative to the barrier 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 barrier member 33 is reduced. At this time, the lifting frame 32 is positioned at a height where the flange portion 34 of the barrier member 33 will not contact the upper plate 32u of the lifting frame 32 (the lower position described later).

[0078] The barrier lifting unit 31 positions the lifting frame 32 in the upper position. Figure 3 The position shown) to the next position ( Figure 2 The positions shown are any positions between the indicated positions. The upper position is when the positioning protrusion 41 is inserted into the positioning hole 42, and the flange portion 34 of the blocking member 33 contacts the lower plate 32L of the lifting frame 32. That is, the upper position is the position where the blocking member 33 is suspended from the lifting frame 32. The lower position is the position where the lower plate 32L is away from the flange portion 34, and the positioning protrusion 41 is pulled out of the positioning hole 42. That is, the lower position is the position where the connection between the lifting frame 32 and the blocking member 33 is released, and the blocking member 33 will not contact any part of the lifting frame 32.

[0079] If the lifting frame 32 and the barrier member 33 are moved to the lower position, the lower end of the cylindrical portion 37 of the barrier 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 barrier member 33 is surrounded by the cylindrical portion 37 of the barrier member 33. Therefore, the space between the upper surface of the substrate W and the lower surface 36L of the barrier member 33 is isolated not only from the ambient gas above the barrier member 33 but also from the ambient gas surrounding the barrier member 33. This improves the airtightness of the space between the upper surface of the substrate W and the lower surface 36L of the barrier member 33.

[0080] Furthermore, if the lifting frame 32 and the blocking member 33 are positioned in the lower position, the blocking member 33 will not collide with the lifting frame 32 even if it rotates relative to the lifting frame 32 around the rotation axis A1. If 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, restricting the relative movement of the upper support portion 43 and the lower support portion 44 in the circumferential direction. In this state, if 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. Thus, the blocking member 33 rotates at the same speed in the same direction as the rotating base 12 while the lifting frame 32 and the central nozzle 45 are stationary.

[0081] The central nozzle 45 includes multiple liquid outlets for ejecting liquid and a gas outlet for ejecting gas. The multiple liquid outlets include a liquid outlet 46 for ejecting a chemical solution, an etching solution outlet 47 for ejecting an etching solution, and an upper rinsing solution outlet 48 for ejecting a rinsing solution. The gas outlet is an upper gas outlet 49 for ejecting an inactive gas. The liquid outlet 46, etching solution outlet 47, and upper rinsing solution 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.

[0082] The etching solution may be a liquid containing at least one of the following: sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, acetic acid, ammonia, hydrogen peroxide, organic acid (e.g., citric acid, oxalic acid, etc.), organic base (e.g., TMAH: tetramethylammonium hydroxide, etc.), surfactant, polyol, and corrosion inhibitor. Sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, acetic acid, ammonia, hydrogen peroxide, citric acid, oxalic acid, and TMAH can also be used as etching solutions.

[0083] Figure 2 Examples indicating that the drug solution is DHF (dilute hydrofluoric acid). Additionally, Figure 2 Examples given include pure water as the flushing fluid supplied to the central nozzle 45 and nitrogen as the inert gas supplied to the central nozzle 45. The flushing fluid supplied to the central nozzle 45 may also be a flushing fluid other than pure water. Similarly, the inert gas supplied to the central nozzle 45 may also be an inert gas other than nitrogen.

[0084] The substrate processing apparatus 1 includes: a chemical solution pipe 50 for guiding a chemical solution to a central nozzle 45; a chemical solution valve 51 installed on the chemical solution pipe 50; an etching solution pipe 52 for guiding an etching solution to the central nozzle 45; an etching solution valve 53 installed on the etching solution pipe 52; an upper rinsing solution pipe 54 for guiding a 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 further 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 gas flow rate supplied from the upper gas pipe 56 to the central nozzle 45.

[0085] 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. Thus, the chemical solution and other processing liquids are supplied to the upper surface of the substrate W.

[0086] When the upper gas valve 57 is opened, nitrogen gas guided by the upper gas pipe 56 is supplied to the central nozzle 45 at a flow rate corresponding to the opening of the upper gas flow rate regulating valve 58, and is ejected obliquely downward from the upper gas outlet 49, which is open 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 in the space between the upper surface of the substrate W and the lower surface 36L of the barrier member 33. Thus, the space between the substrate W and the barrier member 33 is filled with nitrogen gas, reducing the oxygen concentration in the ambient gas. The oxygen concentration in the space between the substrate W and the barrier member 33 changes 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.

[0087] Figure 4 This is an example graph showing the relationship between the etching rate of the three crystal planes of silicon and the concentration of propylene glycol in the etching solution. Figure 5A and Figure 5B This is a diagram used to illustrate the hypothetical mechanism that is hindered by compounds when the contact between hydroxide ions and polycrystalline silicon is impeded. Figure 4 , Figure 5A ,and Figure 5B In this context, "PG" represents propylene glycol.

[0088] The substrate processing apparatus 1 supplies the substrate W with an etchant that dissolves a portion of the substrate W by etching it, and a compound that reduces the anisotropy of the etchant on the single-crystal silicon, either separately or in advance.

[0089] The etching solution is used to etch at least one of monocrystalline silicon and polycrystalline silicon (refer to) without etching or with minimal etching of non-etchable materials such as silicon oxide and silicon nitride. Figure 5A An alkaline liquid is used for etching. The pH (hydrogen ion index) of the etching solution is, for example, 12 or higher. Under the same processing conditions, the amount of etching of the object 91 per unit time is greater than the amount of etching of the non-etched object per unit time.

[0090] Etching solution is a liquid used to anisotropically etch monocrystalline silicon (including monocrystalline silicon in polycrystalline silicon). That is, if the processing conditions are the same, and the (110), (100), and (111) planes of silicon are etched using 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.

[0091] The etching solution can be an aqueous solution of alkali metal hydroxides such as sodium and potassium (aqueous solution of NaOH or KOH), or an aqueous solution of quaternary ammonium hydroxides such as TMAH. Quaternary ammonium hydroxides can be at least one of TMAH, TBAH (tetrabutylammonium hydroxide), TPeAH (tetrapentammonium hydroxide), THAH (tetrahexammonium hydroxide), TEAH (tetraethylammonium hydroxide), TPAH (tetrapropylammonium hydroxide), and cholecysteine ​​hydroxide, or other substances. These are all included in organic bases. Furthermore, in this paragraph, TMAH does not refer to an aqueous solution, but rather to an anhydrous form. This also applies to other quaternary ammonium hydroxides such as TBAH.

[0092] If quaternary ammonium hydroxide dissolves in water, it will decompose into cations and hydroxide ions. Therefore, hydroxide ions will be present in aqueous solutions of quaternary ammonium hydroxide. Similarly, hydroxide ions will also be present in aqueous solutions of alkali metal hydroxides such as sodium and potassium. The compound supplied to the substrate W is a barrier substance that prevents the hydroxide ions from contacting the etched object 91. Preferably, the molecules of the barrier substance are larger than hydroxide ions. Furthermore, it is preferable that the barrier substance is a water-soluble substance. The barrier substance may also be a surfactant having both hydrophilic and hydrophobic groups. If it can be uniformly dispersed in the etching solution, the barrier substance may also be an insoluble substance that does not dissolve in water.

[0093] The etching solution can be supplied to the substrate W either mixed with or undiluted with the compound. The compound is a substance dissolved in the etching solution. The following description uses an example where the compound is a first compound and a second compound. The first compound and the second compound are different substances. The first compound is, for example, a glycol. The second compound is, for example, an ether. The first compound and the second compound can also be substances other than glycols and ethers, such as glycerol.

[0094] The diol can be any of ethylene glycol, diethylene glycol, and propylene glycol. Propylene glycol is preferred. A diol is an example of a substance that does not participate in the reaction between silicon (Si) and hydroxide ions (OH-). That is, a diol is an example of a substance that does not react with atoms that participate in the reaction between silicon and hydroxide ions. A diol is also an example of a substance that does not act as a catalyst in this reaction.

[0095] When an alkaline etching solution containing a compound (a mixture of the compound, hydroxide, and water) is supplied to substrate W, the concentration of hydroxides such as TMAH is, for example, 0.1 to 25 wt%, and the concentration of the compound is, for example, 0.001 to 40 wt%. Preferably, the concentration of the quaternary ammonium hydroxide is 0.25 to 20 wt%. Preferably, the concentration of the compound is 0.5 to 30 wt%.

[0096] Figure 5A and Figure 5B This refers to an example of an etching solution (a mixture of etching solution and propylene glycol) containing propylene glycol, which is an example of a compound, supplied to a polycrystalline silicon object 91. Figure 5A and Figure 5B The "cations" and "OH-" in the etching solution are separated from the hydroxides (alkali metal hydroxides or quaternary ammonium hydroxides) contained in the etching solution.

[0097] The silicon contained in the polycrystalline silicon object 91, as shown in the formula "Si + 4OH- → Si(OH)4 + 4e-", reacts with hydroxide ions. As a result, the silicon contained in the object 91 dissolves in the etching solution, and the object 91 is etched. The compounds contained in the etching solution act as a steric barrier for the hydroxide ions. That is, compounds suspended in the etching solution, or adsorbed or coordinated in the polycrystalline silicon, block the movement of hydroxide ions towards the polycrystalline silicon. Therefore, the number of hydroxide ions reaching the polycrystalline silicon decreases, leading to a reduction in the etching rate. Under this mechanism, it can be considered that the contact between hydroxide ions and polycrystalline silicon is hindered by the compounds.

[0098] Although the decrease in etching rate occurs across multiple crystal planes of the silicon contained in polycrystalline silicon, the etching rate is significantly lower on each of these planes compared to the higher crystal planes. This reduces the etching rate difference across the multiple crystal planes, leading to a decrease in the anisotropy of the etchant on the monocrystalline silicon. In other words, regardless of the orientation of the exposed silicon facets on the polycrystalline silicon surface, the polycrystalline silicon can be etched uniformly. Under this mechanism, it can be considered that the polycrystalline silicon is etched with a uniform etching amount everywhere.

[0099] Figure 4 This represents the measured etching rates of the (110), (100), and (111) planes when etching monocrystalline silicon using three different concentrations of TMAH (zero, first, and second concentrations) of propylene glycol. [Original data is missing from the original text.] Figure 4 The etching conditions for the measured values ​​shown were the same except for the concentration of propylene glycol in the TMAH. For example, the TMAH temperature was 40°C, and the concentration of TMAH without added propylene glycol was 5 wt% (mass percentage concentration). The dissolved oxygen concentration was reduced beforehand with TMAH.

[0100] 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. Observation Figure 4 The three curves show that adding propylene glycol to TMAH reduces the etching rate. Furthermore, the etching rate decreases for any crystal plane as the concentration of propylene glycol increases.

[0101] 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.

[0102] When the concentration of propylene glycol exceeds the first concentration, although the rate of reduction 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 reduction in etching rate for the (110) and (100) faces is greater than that for the (111) face up to a value near the midpoint between the first and second concentrations. Therefore, even if the concentration of propylene glycol is within the range near the midpoint between the first and second concentrations, the difference between the maximum and minimum etching rates decreases as the concentration of propylene glycol increases.

[0103] Thus, if propylene glycol is added to the TMAH, which is anisotropic to monocrystalline silicon, the facet selectivity, i.e., the difference between the maximum and minimum etch rates, will decrease, and the anisotropy of the TMAH to monocrystalline silicon will be reduced. On the other hand, the propylene glycol concentration is in the range of values ​​near the middle of the first and second concentrations. As the concentration of propylene glycol increases, the etch rates of the (110) and (100) faces decrease at a greater rate. Therefore, the concentration of propylene glycol can be set according to the desired etch uniformity and etch rate.

[0104] For example, excess propylene glycol or other hindering substances can be added to the etching solution. Figure 4 The test results show that when a small amount of propylene glycol is added (e.g., about 5-10 wt%), the anisotropy mitigation effect is relatively small. However, when a large amount of propylene glycol is added (e.g., more than 20 wt%), i.e., when excess propylene glycol is added, a significant anisotropy mitigation effect can be observed. On the other hand, since the etching rate will decrease, it is preferable to select the concentration of propylene glycol according to the required quality and the allowable processing time.

[0105] Figure 4 The trend shown can be confirmed even with 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 trend shown is confirmed not only when the compound-containing etchant is supplied to the object to be etched 91, but also when the compound and etchant are supplied separately to the substrate W and then mixed on the object to be etched 91. Therefore, it is also possible to supply the compound and etchant separately to the substrate W.

[0106] The compound supplied to the substrate W can be either the first compound or the second compound, or both of the first compound and the second compound. In the former case, the etching solution and the second compound can be supplied to the etching target 91 before or after the etching solution and the first compound are supplied to the etching target 91. That is, the first compound and the second compound can be present on the etching target 91 as long as the liquid on the etching target 91 is replaced by another liquid. In the latter case, the etching solution containing the first compound and the second compound can be supplied to the etching target 91, or the first compound, the second compound, and the etching solution can be mixed on the etching target 91.

[0107] When the compound supplied to the substrate W is one of the first compound and the second compound, two or more compounds belonging to the first compound or the second compound may also be supplied to the etching target 91. For example, two or more compounds belonging to the first compound may be supplied to the etching target 91. In this case, an etching solution containing all the compounds may also be supplied to the etching target 91, or all the compounds may be mixed with the etching solution on the etching target 91. Alternatively, the remaining compounds may be supplied to the etching target 91 before or after an etching solution containing several compounds is supplied to the etching target 91.

[0108] If the conditions other than the type of compound (including combinations of compounds) are the same, at least one of the etching rates of the (110), (100), and (111) faces of silicon will be different when different types of compounds are supplied to the object to be etched 91. Therefore, it is preferable to select the type of compound based on the required quality and the allowable processing time.

[0109] When the etching solution is supplied to the object to be etched 91 without supplying the compound, if the temperature of the etching solution rises, the etching rate of the (110) and (100) surfaces will increase by a greater amount than the change in the etching rate of the (111) surface. Conversely, if the temperature of the etching solution decreases, the etching rate of the (110) and (100) surfaces will decrease by a greater amount than the change in the etching rate of the (111) surface.

[0110] Therefore, when the etching solution is supplied to the object being etched 91 without supplying the compound, if the temperature of the etching solution rises, the difference between the minimum and maximum etching rates of silicon increases. Conversely, when the etching solution is supplied to the object being etched 91 without supplying the compound, if the temperature of the etching solution decreases, the difference between the minimum and maximum etching rates of silicon decreases. These phenomena also occur when both the etching solution and the compound are supplied to the object being etched. Therefore, it is preferable to set the temperature of the etching solution and the compound according to the required quality and the permissible processing time.

[0111] Figure 6 This is a schematic diagram of a processing liquid supply unit 61 of a substrate processing apparatus 1 that supplies processing liquids such as etching solution to a substrate W. Figure 6 This illustrates an example of etchant being mixed with a compound before being supplied to substrate W.

[0112] 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 center nozzle 45, etching liquid piping 52, and etching liquid valve 53 are included in the processing liquid supply unit 61.

[0113] In addition to the central nozzle 45, the processing fluid supply unit 61 also includes: an etching fluid tank 62 for storing etching fluid, a first compound tank 70 for storing a solution containing a first compound (an example of a compound), and a second compound tank 75 for storing a solution containing a second compound (an example of a second compound). The solution containing the first compound can be a liquid (melt) of the first compound or a solution of the first compound. When the solution containing the first compound is a solution of the first compound, the solvent can be water or a liquid other than water, such as etching fluid. The same applies to the solution containing the second compound.

[0114] The etching solution in the etching solution tank 62 is supplied to the central nozzle 45 via the mixing valve 80. Similarly, the solution containing the first compound in the first compound tank 70 is supplied to the central nozzle 45 via the mixing valve 80, and the solution containing the second compound in the second compound tank 75 is supplied to the central nozzle 45 via the mixing valve 80. When the etching solution containing at least one of the first compound and the second compound is sprayed toward the central nozzle 45, at least one of the solutions containing the first compound and the second compound, along with the etching solution, is supplied to the mixing valve 80 for mixing.

[0115] The processing fluid supply unit 61 may further include an inline mixer 81 that stirs the etching fluid containing at least one of the first compound and the second compound before it is ejected from the central nozzle 45 through the mixing valve 80. Figure 6 This illustrates an example where an in-line mixer 81 is positioned upstream of an etching solution valve 53. The in-line mixer 81 is a static mixer comprising a pipe 81p and a stirring fin 81f; the pipe 81p is installed in an upstream etching solution piping 67; the stirring fin 81f is disposed within the pipe 81p and performs static mixing around an axis extending in the direction of liquid flow.

[0116] The processing fluid supply unit 61 includes a circulation piping 63, a circulation pump 64, a filter 66, and a temperature regulator 65. The circulation piping 63 circulates the etching fluid in the etching fluid tank 62. The circulation pump 64 delivers the etching fluid in the etching fluid tank 62 to the circulation piping 63. The filter 66 removes foreign matter such as particles from the etching fluid returning to the etching fluid tank 62. The temperature regulator 65 changes the temperature of the etching fluid in the etching fluid tank 62 by heating or cooling the etching fluid.

[0117] The circulation pump 64 always delivers the etching solution from the etching solution tank 62 to the circulation piping 63. The etching solution in the etching solution tank 62 flows into the circulation piping 63 through its upstream end and returns to the etching solution tank 62 through its downstream end. Thus, the etching solution circulates in the circulation path formed by the etching solution tank 62 and the circulation piping 63.

[0118] Temperature regulator 65 maintains the temperature of the etching solution in etching solution tank 62 at a certain temperature, which is higher or lower than room temperature (e.g., 20-30°C). Temperature regulator 65 can also be installed in circulation piping 63 or disposed in etching solution tank 62. Figure 6 This refers to an example of the former. Temperature regulator 65 is a heater that can heat liquids at temperatures above room temperature, or a cooler that can cool liquids at temperatures below room temperature, or it can have both heating and cooling functions.

[0119] The processing fluid supply unit 61 further includes: an upstream etching fluid pipe 67 that guides the etching fluid from the circulation pipe 63 to the central nozzle 45; a flow regulating valve 69 that changes the flow rate of the etching fluid flowing downstream in the upstream etching fluid pipe 67; and an in-line heater 68 that heats the etching fluid flowing into the upstream etching fluid pipe 67.

[0120] The etching solution in the circulating piping 63 flows into the upstream etching solution piping 67 through its upstream end, and is then supplied to the mixing valve 80 through its downstream end. At this time, the etching solution is supplied to the mixing valve 80 at a flow rate corresponding to the opening of the flow regulating valve 69. When supplying etching solution with a temperature higher than that in the etching solution tank 62 to the mixing valve 80, the etching solution is heated by the in-line heater 68 before being supplied to the mixing valve 80.

[0121] The substrate processing apparatus 1 may also include a dissolved oxygen concentration adjustment unit 82 for adjusting the dissolved oxygen concentration of the etching solution. The dissolved oxygen concentration adjustment unit 82 includes a gas pipe 83 that dissolves gas into the etching solution within the etching solution tank 62 by supplying gas into the etching solution tank 62. The dissolved oxygen concentration adjustment unit 82 further includes an inactive gas pipe 84, an inactive gas valve 85, and a flow regulating valve 86. The inactive gas pipe 84 supplies inactive gas to the gas pipe 83. The inactive gas valve 85 opens and closes between an open state where inactive gas flows from the inactive gas pipe 84 into the gas pipe 83 and a closed state where inactive gas is blocked in the inactive gas pipe 84. The flow regulating valve 86 adjusts the flow rate of inactive gas supplied from the inactive gas pipe 84 to the gas pipe 83.

[0122] Gas piping 83 is a foaming pipe containing a gas outlet 83p within the etching solution in the etching solution tank 62. When the inactive gas valve 85 is opened (i.e., switched from a closed to an open state), inactive gases such as nitrogen are ejected from the gas outlet 83p at a flow rate corresponding to the opening degree of the flow regulating valve 86. This forms multiple bubbles in the etching solution within the etching solution tank 62, and the inactive gases dissolve into the etching solution. At this time, dissolved oxygen is expelled from the etching solution, reducing its concentration. The dissolved oxygen concentration in the etching solution tank 62 is changed by altering the flow rate of nitrogen ejected from the gas outlet 83p.

[0123] The processing fluid supply unit 61 includes: a first compound pipe 71, a first compound pump 72, a filter 73, and a flow regulating valve 74. The first compound pipe 71 guides the first compound-containing solution from the first compound tank 70 to the central nozzle 45. The first compound pump 72 delivers the first compound-containing solution in the first compound tank 70 to the first compound pipe 71. The filter 73 removes foreign matter such as particles from the first compound-containing solution flowing into the central nozzle 45. The flow regulating valve 74 changes the flow rate of the first compound-containing solution flowing downstream in the first compound pipe 71.

[0124] The processing fluid supply unit 61 further includes: a second compound piping 76, a second compound pump 77, a filter 78, and a flow regulating valve 79. The second compound piping 76 guides the solution containing the second compound from the second compound tank 75 to the central nozzle 45. The second compound pump 77 delivers the solution containing the second compound in the second compound tank 75 to the second compound piping 76. The filter 78 removes foreign matter such as particles from the solution containing the second compound flowing into the central nozzle 45. The flow regulating valve 79 changes the flow rate of the solution containing the second compound flowing downstream in the second compound piping 76.

[0125] When circulating the solution containing the first compound in the first compound tank 70, the same configuration as the etching solution can be used. That is, only the circulation piping 63 and circulation pump 64 for the solution containing the first compound need to be installed. When supplying the solution containing the first compound at a temperature higher or lower than room temperature to the mixing valve 80, only at least one of the temperature regulator 65 for the solution containing the first compound and the in-line heater 68 needs to be installed. When reducing the dissolved oxygen concentration of the solution containing the first compound, only the gas piping 83 for the solution containing the first compound needs to be installed. The same applies to the solution containing the second compound.

[0126] The mixing valve 80 includes: multiple valves that can be opened and closed individually, and multiple flow paths connecting the multiple valves. Figure 6This example illustrates a mixing valve 80 comprising three valves (valve V1, valve V2, and valve V3), three inlets (inlet Pi1, inlet Pi2, and inlet Pi3), and one outlet Po. An upstream etchant piping 67 is connected to inlet Pi1. A first compound piping 71 is connected to inlet Pi2, and a second compound piping 76 is connected to inlet Pi3. An etchant piping 52 is connected to outlet Po.

[0127] If valve V1 is opened, the etching solution in the upstream etching solution pipe 67 flows into the mixing valve 80 through the first inlet Pi1 and is discharged from the outlet Po to the etching solution pipe 52. Similarly, if valve V2 is opened, the solution containing the first compound in the first compound pipe 71 flows into the mixing valve 80 through the second inlet Pi2 and is discharged from the outlet Po to the etching solution pipe 52. If valve V3 is opened, the solution containing the second compound in the second compound pipe 76 flows into the mixing valve 80 through the third inlet Pi3 and is discharged from the outlet Po to the etching solution pipe 52.

[0128] For example, when valves V1 and V2 are opened, the etching solution is supplied to the mixing valve 80 at a flow rate corresponding to the opening of the flow control valve 69, while the solution containing the first compound is supplied to the mixing valve 80 at a flow rate corresponding to the opening of the flow control valve 74. Thus, the etching solution containing the first compound is supplied from the mixing valve 80 to the etching solution piping 52 and ejected from the central nozzle 45 toward the substrate W. The concentration of the first compound in the etching solution ejected from the central nozzle 45 is varied using the flow control valves 69 and 74. The temperature of the etching solution containing the first compound ejected from the central nozzle 45 is varied using the temperature regulator 65 and the in-line heater 68.

[0129] Figure 7 This is a block diagram showing the electrical configuration of the substrate processing apparatus 1.

[0130] The control device 3 is a computer comprising a computer body 3a and peripheral devices 3d connected to the computer body 3a. The computer body 3a includes a CPU 3b (central processing unit) that executes various commands and a main storage device 3c that stores information. The peripheral devices 3d include an auxiliary storage device 3e that stores information such as the program P, a reading device 3f that reads information from a removable medium RM, and a communication device 3g that communicates with the host computer and other devices.

[0131] The control device 3 is connected to the input device and the display device. The input device is operated by the user or maintenance personnel when inputting 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, and a touchpad, or other devices. A touchpad display that serves as both an input device and a display device can also be provided in the board processing device 1.

[0132] CPU 3b executes the program P stored in auxiliary storage device 3e. The program P in auxiliary storage device 3e can be pre-installed in control device 3, or it can be transferred to auxiliary storage device 3e from removable medium RM via reading device 3f, or it can be transferred to auxiliary storage device 3e from external devices such as host computer via communication device 3g.

[0133] Auxiliary storage device 3e and removable medium RM are non-volatile memories that retain storage even when no power is supplied. Auxiliary storage device 3e is a magnetic storage device such as a hard disk drive. Removable medium RM is a semiconductor memory such as a compact disc (CD) or a memory card. Removable medium RM is an example of a computer-readable recording medium that records a program P. Removable medium RM is a non-transitory tangible recording medium.

[0134] The auxiliary storage device 3e stores multiple procedures. Each procedure specifies the processing content, processing conditions, and processing sequence of the substrate W. The multiple procedures differ from each other in at least one of the processing content, processing conditions, and processing sequence of the substrate W. The control device 3 controls the substrate processing device 1 to process the substrate W according to the procedures specified by the host computer. The control device 3 is programmed to execute the steps described later.

[0135] Figure 8 This is a step 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 ,and Figure 8 .

[0136] When the substrate W is processed by the substrate processing apparatus 1, a transfer step is performed to transfer the substrate W into the chamber 4. Figure 8 Step S1 in the process.

[0137] Specifically, with the lifting frame 32 and the barrier member 33 in the upper position and all protective covers 25 in the lower position, the central robotic arm CR supports the substrate W with its hand H1 while extending the hand H1 into the chamber 4. Then, with the surface of the substrate W facing upwards, the central robotic arm CR places the substrate W on the hand H1 onto multiple chuck pins 11. The multiple chuck pins 11 then press against the outer peripheral surface of the substrate W, holding the substrate W in place. After placing the substrate W onto the rotating chuck 10, the central robotic arm CR withdraws the hand H1 from inside the chamber 4.

[0138] 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 barrier 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. Additionally, the barrier 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 one of the protective covers 25 from the lower position to the upper position. At this time, the rotating base 12 maintains a reference rotation angle where, from a top view, the multiple upper supports 43 overlap the multiple lower supports 44. Therefore, the upper supports 43 of the barrier member 33 are supported by the lower supports 44 of the rotating base 12, and the barrier member 33 moves away from the lifting frame 32. Then, the rotary motor 14 is driven to begin the rotation of the substrate W. Figure 8 Step S2 in the process.

[0139] Next, a solution supply step is performed, in which DHF, an example of a solution, is supplied to the upper surface of the substrate W. Figure 8 Step S3 in the process.

[0140] Specifically, with the barrier 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, after colliding with the center of the upper surface of the substrate W, 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, thus supplying DHF to the entire upper surface of the substrate W. If a predetermined time elapses after opening the liquid valve 51, the liquid valve 51 is closed, stopping the spraying of DHF.

[0141] Next, a first rinsing solution supply step is performed, in which pure water, an example of a rinsing solution, is supplied to the upper surface of the substrate W. Figure 8 Step S4 in the process.

[0142] Specifically, with the barrier member 33 in the lower position, the upper flushing fluid valve 55 is opened, and pure water is sprayed from the central nozzle 45. The pure water that collides with the center of the upper surface of the substrate W flows outward along the upper surface of the rotating substrate W. The DHF on the substrate W is rinsed by the pure water sprayed from the central nozzle 45. As a result, a pure water film covering the entire upper surface of the substrate W is formed. If a predetermined time has elapsed since the upper flushing fluid valve 55 was opened, the upper flushing fluid valve 55 is closed, and the spraying of pure water stops.

[0143] Next, a first etching step is performed, in which an example of an etching solution, namely the first etching solution, is supplied to the upper surface of the substrate W. Figure 8 Step S5 in the process.

[0144] Specifically, with the barrier 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 also opened. As a result, the first etching solution, i.e., the etching solution containing the first compound, is supplied to the central nozzle 45, and the central nozzle 45 begins to spray the first etching solution. Before the first etching solution is sprayed, the protective cover lifting unit 27 can also vertically move at least one protective cover 25 to switch the receiving 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 upper surface of the rotating substrate W. The pure water on the substrate W is replaced by the first etching solution sprayed from the central nozzle 45. Thus, a first etching solution film covering the entire upper surface of the substrate W is formed.

[0145] After the first etchant film is formed, a second etching step is performed by supplying another type of etchant, namely the second etchant, to the upper surface of the substrate W. Figure 8 Step S6 in the process.

[0146] Specifically, while keeping 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 [reference]). Figure 6 The opening degree of the mixing valve 80. If 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 solution containing the first compound to the mixing valve 80 stops, and the supply of the solution containing the second compound to the mixing valve 80 begins. As a result, the second etchant, i.e., the etchant containing the second compound, is supplied to the central nozzle 45, and the central nozzle 45 begins to spray the second etchant. Before the second etchant is sprayed, in order to switch the protective cover 25 that receives the liquid discharged from the substrate W, the protective cover lifting unit 27 can also move at least one protective cover 25 vertically.

[0147] With the barrier member 33 in the lower position, the second etchant is ejected from the central nozzle 45 toward the center of the upper surface of the substrate W. The second etchant, impacting 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. This forms a second etchant film covering the entire upper surface of the substrate W.

[0148] After the liquid film of the second etchant is formed, the first etchant can be supplied to the substrate W again, and then the second etchant can be supplied to the substrate W. That is, the first etching step ( Figure 8 Step S5) to the second etching step ( Figure 8 Step S6) is performed more than twice in one loop. Figure 8 Step S7 in the process. Figure 8 In step S7, "N" represents an integer greater than or equal to 0. When N is greater than or equal to 1, the process is repeated at least twice. When N is 0, only the first and second etching steps are performed in the first iteration, while subsequent first and second etching steps are not performed.

[0149] After the final second etching step begins, forming a second etchant film covering the entire upper surface of the substrate W, all valves of the mixing valve 80 (valve V1, valve V2, and valve V3) are closed, and the etchant valve 53 is also closed. Thus, with the entire upper surface of the substrate W covered by the second etchant film, the ejection of the second etchant from the central nozzle 45 ceases.

[0150] Next, a second rinsing solution supply step is performed, in which pure water, an example of a rinsing solution, is supplied to the upper surface of the substrate W. Figure 8 Step S8 in the process.

[0151] Specifically, with the barrier member 33 in the lower position, the upper rinsing fluid valve 55 is opened, and pure water is sprayed from the central nozzle 45. The pure water that collides with the center of the upper surface of the substrate W flows outward along the upper surface of the rotating 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 pure water film covering the entire upper surface of the substrate W is formed. After a predetermined time has elapsed since the upper rinsing fluid valve 55 was opened, the upper rinsing fluid valve 55 is closed, and the spraying of pure water stops.

[0152] Next, a drying step is performed to dry the substrate W by rotating the substrate W. Figure 8 Step S9 in the process.

[0153] Specifically, with the barrier member 33 in the lower position, the rotary motor 14 accelerates the substrate W in the rotational direction to a high rotational 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. As a result, liquid is removed from the substrate W, and the substrate W is dried. If a predetermined time elapses after the substrate W begins high-speed rotation, the rotary motor 14 stops rotating. At this time, the rotary motor 14 stops rotating the base 12 at a reference rotation angle. Thus, the rotation of the substrate W is stopped. Figure 8 Step S10 in the process.

[0154] Next, the removal step of removing the substrate W from chamber 4 is performed. Figure 8 Step S11 in the process.

[0155] Specifically, the barrier lifting unit 31 raises the lifting frame 32 to the upper position, and the protective cover lifting unit 27 lowers all protective covers 25 to the lower position. Additionally, 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 barrier member 33 and the lower central opening 18 of the rotating base 12. Then, the central robotic arm CR extends its hand H1 into the chamber 4. After the multiple chuck pins 11 release the substrate W, the central robotic arm 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 robotic arm CR withdraws its hand H1 from inside the chamber 4. Thus, the processed substrate W is removed from the chamber 4.

[0156] Table 1 below shows several examples of substrate W processing performed by substrate processing apparatus 1. In Table 1, “Compound X” indicates at least one of compound 1 and compound 2, and “+” in Table 1 indicates that a mixture of etchant and compound is supplied to the upper surface of substrate W.

[0157] [Table 1]

[0158]

[0159] Compound X is at least one of compound 1 and compound 2.

[0160] The third processing example requires a second etching step after the first one.

[0161] In the foregoing description, an example (first processing example) is described in which a first etchant (etchant containing a first compound) is supplied to the upper surface of the substrate W, and then a second etchant (etchant containing a second compound) is supplied to the upper surface of the substrate W.

[0162] As shown in the second processing example in Table 1, an etch solution without the first compound and the second compound can be supplied to the upper surface of the substrate W in the first etching step, and an etch solution containing at least one of the first compound and the second compound can be supplied to the upper surface of the substrate W in the second etching step.

[0163] Alternatively, as shown in the third processing example in Table 1, in the first etching step, an etch solution without the compound is supplied to the upper surface of the substrate W, and in the second etching step, a compound-containing solution is supplied to the upper surface of the substrate W. In this case, if the compound-containing solution is supplied to the entire upper surface of the substrate W, etching of the entire upper surface of the substrate W stops or almost stops. If, after supplying the compound-containing solution, an etch solution without the compound is supplied to the upper surface of the substrate W (the second first etching step), the compound contained in the compound-containing solution on the substrate W will dissolve into the etch solution, and the compound-containing etch solution will be supplied to the entire upper surface of the substrate W. Therefore, the anisotropy of etching can be reduced in the second and subsequent first etching steps compared to the first first etching step. Therefore, anisotropic etching is performed in the first first etching step, while isotropic etching is performed in the second and subsequent first etching steps.

[0164] Alternatively, as shown in the fourth processing example in Table 1, in the first etching step, an etching solution with a concentration of at least one of the first compound and the second compound of Cx% (Cx is a value greater than 0) is supplied to the upper surface of the substrate W, and in the second etching step, an etching solution with a concentration of at least one of the first compound and the second compound of Cy% (Cy is a value greater than 0 and different from Cx) is supplied to the upper surface of the substrate W.

[0165] Alternatively, as shown in the fifth processing example in Table 1, in the first etching step, an etching solution containing at least one of the first compound and the second compound and at a temperature of Tx is supplied to the upper surface of the substrate W, and in the second etching step, an etching solution containing at least one of the first compound and the second compound and at a temperature of Ty (Ty is different from Tx) is supplied to the upper surface of the substrate W.

[0166] Figure 9A It means in Figure 8 A schematic diagram of a cross-section of substrate W after the first etching solution has been supplied, in one example of substrate W processing shown. Figure 9B It means in Figure 8 A schematic diagram of a cross-section of substrate W after the second etching solution has been supplied, in one example of substrate W processing shown. Figure 10 It means in Figure 8 The graph shown illustrates the relationship between processing time and etching rate when the first etchant and the second etchant are supplied alternately multiple times in one example of substrate W processing. Figure 10In the figure, Pt represents the period during which the second etchant was ejected.

[0167] exist Figures 9A-9B In the example shown, the substrate W is a silicon wafer before patterning (a so-called "bare wafer" (a disc-shaped monocrystalline silicon wafer)), and the etched object 91 is the upper surface of the silicon wafer. The upper surface of the silicon wafer is, for example, the (100) surface.

[0168] Figure 9A The double-dotted line in the figure represents the shape of the upper surface of the silicon wafer after the natural oxide film of silicon has been removed by supplying DHF and before the first etchant is supplied. Figure 9A The solid line in the figure represents the shape of the upper surface of the silicon wafer after the first etch solution has been supplied. Figure 9B The double-dotted line in the figure represents the shape of the upper surface of the silicon wafer after the first etchant is supplied and before the second etchant is supplied. Figure 9B The solid line in the figure represents the shape of the upper surface of the silicon wafer after the second etching solution is supplied.

[0169] In the following description, the maximum etching rate when the first etchant is supplied to the (110), (100), and (111) faces of silicon is greater than the maximum etching rate when the second etchant is supplied to the (110), (100), and (111) faces of silicon. The difference between the maximum and minimum etching rates when the first etchant is supplied is greater than the difference between the maximum and minimum etching rates when the second etchant is supplied. That is, compared to the second etchant, although the anisotropy of etching is greater with the first etchant, the etching rate is higher (etch rate is higher).

[0170] As mentioned above, the first etchant is an etchant containing the first compound. If the etchant contained in the first etchant is used to etch the monocrystalline silicon, the etching rate will be different on each crystal surface. However, before the first etchant is initially supplied to the substrate W, the upper surface of the substrate W (the upper surface of the disc-shaped monocrystalline silicon) is a (100) surface, and the (100) surface is exposed at any point on the upper surface of the substrate W. Therefore, if the first etchant is supplied to the upper surface of the substrate W, the upper surface of the substrate W will be etched uniformly while the upper surface of the substrate W is flat.

[0171] However, as Figure 9A As shown by the solid line, if the upper surface of substrate W is etched, the upper surface of substrate W will become non-flat. This is because cracks and defects exist in single-crystal silicon. That is, if cracks and defects exist, the (111) surface with a relatively low etching rate will be exposed, resulting in uneven etching. Therefore, multiple protrusions 92 will be formed on the upper surface of substrate W. Figure 9AThis example illustrates the formation of multiple pyramid-shaped protrusions 92 on the upper surface of a substrate W. The sides of the pyramid-shaped protrusions 92 are (111) surfaces, resulting in a relatively low etching rate. If such protrusions 92 remain on the substrate W after processing, the substrate W will be deemed to have poor quality, such as rough surface or insufficient etching.

[0172] like Figure 10 As shown, if the first etchant is supplied, the etching rate decreases over time. This is because the protrusion 92 exposed on the (111) surface gradually increases in size, resulting in a reduction in the contact area between the (100) surface and the first etchant. After a predetermined time has elapsed since the first etchant was supplied, a second etchant with a lower anisotropy than the first etchant is supplied to the upper surface of the substrate W. Therefore, although the etching rate is lower than that of the first etchant (see reference...), the etching rate decreases over time. Figure 10 During the period Pt), not only the flat portion of the upper surface of the substrate W (the portion exposing the (100) surface) but also the side surface of the protrusion 92 (the portion exposing the (111) surface) is etched. Thus, as Figure 9B As shown, the protrusion 92 gradually becomes smaller or the protrusion 92 disappears from the upper surface of the substrate W.

[0173] After a predetermined time has elapsed since the start of the second etchant supply, the first etchant is supplied to the upper surface of the substrate W again. Because the protrusion 92 is miniaturized or removed by the supply of the second etchant, supplying the first etchant to the upper surface of the substrate W allows for uniform etching of the upper surface of the substrate W while it remains flat or approximately flat. Even if the protrusion 92 is re-formed or enlarged due to the second supply of the first etchant, the protrusion 92 can still be miniaturized or removed by the second supply of the second etchant. Therefore, the flatness (planarity) of the upper surface of the processed substrate W can be improved.

[0174] Therefore, by alternately supplying the substrate W with a first etchant that has a relatively high etching rate and a second etchant that has relatively low anisotropy, the processing time can be shortened, and the upper surface of the substrate W can be etched uniformly. That is, if only the second etchant is continuously supplied, although the upper surface of the substrate W can be etched uniformly, the etching time is long because the etching rate of the second etchant is relatively low. In contrast, by alternately supplying the first and second etchants to the substrate W, the processing time can be shortened while ensuring the same flatness of the upper surface of the substrate W, compared to the case of continuously supplying only the second etchant.

[0175] Figure 11 This is a schematic diagram showing the cross-section of the aforementioned fin after etching with a compound-free etching solution. Figure 12 It means in Figure 8The schematic diagram shows a cross-section of the silicon fin after alternating supply of a first etchant and a second etchant to etch the substrate W in one example of substrate W processing.

[0176] Figure 11 The double-dotted line in the image indicates the shape of the fin before the supply of the etchant containing the compound. Figure 11 The solid lines in the figure represent the shape of the fins after the supply of etchant without compounds. Figure 12 The double-dotted line in the image indicates the shape of the fin before the first etchant is supplied. Figure 12 The dotted lines in the diagram represent the fin shape after the first etchant was supplied and before the second etchant was supplied. Figure 12 The solid line in the figure represents the shape of the fin after the second etching solution is supplied.

[0177] exist Figure 11 and Figure 12 In the example shown, the substrate W is a patterned silicon wafer, and the object to be etched 91 is the surface layer of a fin formed on the upper surface of the substrate W. The fin is formed of monocrystalline silicon. The upper surface of the fin is a (100) plane, and the right and left sides of the fin are (110) planes. Although not shown, in addition to the object to be etched, i.e., the fin, non-etchable materials such as silicon oxide and silicon nitride may also be exposed on the surface of the substrate W. In this case, selective etching of the object to be etched 91 is performed while suppressing the etching of the object to be etched.

[0178] Because alkaline etchants are anisotropic, supplying a compound-free etchant to the upper surface of substrate W is like... Figure 11 As shown, the fin surface formed from monocrystalline silicon will be etched unevenly. Figure 11 This example illustrates how the etching amount decreases as you approach the lower end of the fin, and how the fin becomes thicker as you get closer to the lower end. The reason is that the (100) and (110) surfaces, with relatively high etching rates, are located on the upper and side surfaces of the fin, while the (111) surface, with a relatively low etching rate, faces upwards. Therefore, etching downwards and in the width direction is relatively faster, while etching downwards at an angle is relatively slower.

[0179] like Figure 12 As shown by the dashed lines, if the first etchant, which has a relatively high etching rate, is supplied to the upper surface of the substrate W, the surface layer of the fin will be etched rapidly. However, compared to the second etchant, due to its greater anisotropy, the amount of fin etched decreases as it approaches the lower end of the fin, similar to the case where the etchant without compounds is supplied to the upper surface of the substrate W.

[0180] After a predetermined time has elapsed since the first etchant was supplied, a second etchant, with a lower anisotropy than the first etchant, is supplied to the upper surface of the substrate W. This reduces the difference between the maximum and minimum etching rates, thus increasing the etching rate of the (111) face. Consequently, the fin shape before the first etchant was supplied, i.e. Figure 12 The shape shown by the double-dotted lines allows for uniform etching of the fin surface. This enables the fin to precisely approximate the desired shape while reducing processing time.

[0181] In this embodiment as described above, an alkaline first etchant (an alkaline etchant containing a first compound) is supplied to the substrate W, which exposes the etchable object 91 representing at least one of monocrystalline silicon and polycrystalline silicon. As a result, the etchable object 91 is etched. Then, before (or after) the first etchant is supplied to the substrate W, an alkaline second etchant (an alkaline etchant containing a second compound) is supplied to the substrate W. This further etches the etchable object 91.

[0182] The second etchant is a liquid containing a compound that hinders the contact between hydroxide ions and the object being etched, 91. This compound causes variations in etching anisotropy and etching rate. Specifically, the difference between the maximum and minimum etching rates for the (110), (100), and (111) planes of silicon is smaller in the second etchant than in the first etchant. That is, the etching anisotropy of the second etchant is smaller than that of the first etchant. Furthermore, the maximum etching rate of the second etchant for these crystalline planes is smaller than that of the first etchant.

[0183] If the first etchant is supplied to the substrate W, although the etching uniformity is worse than that of the second etchant, the object 91 can be etched at a higher speed. If the second etchant is supplied to the substrate W, although the etching is slower than that of the first etchant, the object 91 can be etched uniformly. Therefore, by supplying the first and second etchants, which have different etching anisotropy and etching rates, to the substrate W, the processing time can be shortened compared to the case of continuously supplying the second etchant, and the object 91 can be etched uniformly.

[0184] In this embodiment, after the first etchant is supplied to the substrate W, instead of supplying a liquid other than the second etchant, the second etchant is supplied to the substrate W. As a result, the first etchant on the substrate W is replaced by the second etchant. If the object to be etched 91 is oxidized, the surface layer of the object to be etched 91 will change to silicon oxide. Silicon oxide is not, or hardly is, etched by alkaline etchants.

[0185] If the second etchant is supplied to the substrate W immediately after the first etchant is supplied, the time from the supply of the first etchant to the supply of the second etchant can be shortened, thus suppressing or preventing oxidation of the etched object 91. Therefore, compared to continuously supplying the second etchant, the processing time can be shortened, and the actual shape of the etched object 91 can be made closer to the desired shape.

[0186] In this embodiment, not only the second etchant but also the first etchant contains compounds. Therefore, the first etchant also reduces the anisotropy of etching. The first and second etchants differ from each other in at least one of their composition, concentration, and temperature. If at least one of these differs, the anisotropy of etching and the etching rate will change. Thus, compared to continuously supplying the second etchant, the processing time can be shortened, and the object 91 can be etched uniformly.

[0187] In this embodiment, the first etchant and the second etchant are alternately supplied to the substrate W multiple times. If the first etchant, which has a greater anisotropy, is continuously supplied to the substrate W, the area of ​​the (111) surface exposed at a lower etching rate will increase. In this case, because the contact area between the crystal surfaces other than the (111) surface and the first etchant is reduced, the etching rate decreases. If the second etchant, which has a smaller anisotropy, is supplied, the (111) surface is etched. The area of ​​the crystal surface exposed decreases. Then, if the first etchant is supplied to the substrate W, the substrate W can be etched again at a higher etching rate.

[0188] Next, the second embodiment will be described.

[0189] The main difference between the first and second embodiments is that the substrate processing apparatus 101 is a batch processing apparatus that processes multiple substrates W at the same time.

[0190] Figure 13 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 13 In the middle, regarding the aforementioned Figure 1~ Figure 12 The configuration shown is the same as that in Figure 1, and the description is omitted.

[0191] The substrate processing apparatus 101 includes multiple processing units, a conveying unit, and a control device 3. The multiple processing units process multiple substrates W simultaneously. The conveying unit performs an infeeding operation to move the multiple substrates W into the processing unit and an outfeeding operation to move the multiple substrates W out of the processing unit. The control device 3 controls 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 further include a rinsing solution processing unit that simultaneously supplies rinsing solution to the multiple substrates W to which etching solution has been supplied, and a drying processing unit that simultaneously dries the multiple substrates W to which rinsing solution has been supplied.

[0192] The etching unit 104 includes an immersion tank 105 for storing etching solution and simultaneously transferring multiple substrates W. The transfer unit includes a support frame 103 and a lift 102. The support frame 103 holds the multiple substrates W in a vertical position. The lift 102 moves the support frame 103 up and down between a lower position and an upper position. The lower position is where the multiple substrates W held by the support frame 103 are immersed in the etching solution in the immersion tank 105. The upper position is where the multiple substrates W held by the support frame 103 are located above the etching solution in the immersion tank 105.

[0193] The etching unit 104 further includes: a plurality of etching solution nozzles 106 with etching solution outlets for ejecting etching solution, and a plurality of gas nozzles 114 with gas outlets for ejecting inactive gases. The etching solution nozzles 106 and gas nozzles 114 are both horizontally extending cylindrical sections within the immersion tank 105. The plurality of etching solution nozzles 106 and gas nozzles 114 are arranged horizontally parallel to each other. One or more gas nozzles 114 are arranged between two adjacent etching solution nozzles 106. When the support frame 103 is positioned in the lower position (… Figure 13 At the position shown, multiple etchant nozzles 106 and multiple gas nozzles 114 are arranged below multiple substrates W held by the support frame 103.

[0194] Etching solution piping 107 is connected to multiple etching solution nozzles 106. Etching solution piping 107 includes a common piping 107c for guiding the etching solution supplied to the multiple etching solution nozzles 106, and multiple branch pipes 107d for supplying the etching solution supplied from the common piping 107c to the multiple 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 multiple branch pipes 107d branch off from the common piping 107c. The multiple branch pipes 107d are respectively connected to the multiple etching solution nozzles 106. Figure 13 In the diagram, only two etchant nozzles 106 on each side are shown connected to the branch pipe 107d, but other etchant nozzles 106 are also connected to the branch pipe 107d.

[0195] Gas piping 115 is connected to multiple gas nozzles 114. Gas piping 115 includes a common piping 115c for guiding gas supplied to the multiple gas nozzles 114, and multiple branch pipes 115d for supplying gas from the common piping 115c to the multiple gas nozzles 114. The common piping 115c is connected to an inactive gas supply source. Gas valve 116 and flow regulating valve 117 are installed on the common piping 115c. Multiple branch pipes 115d branch off from the common piping 115c. The multiple branch pipes 115d are respectively connected to the multiple gas nozzles 114. Figure 13 In the diagram, only two gas nozzles 114 on each side are shown connected to the branch pipe 115d, but other gas nozzles 114 are also connected to the branch pipe 115d.

[0196] The etching unit 104 includes an overflow tank 113 for receiving 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 piping 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 within the immersion tank 105 by heating or cooling the etching solution.

[0197] If etching solution is ejected from the multiple etching solution 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. Etching solution overflowing from the opening provided at the upper end of the immersion tank 105 is received by the overflow tank 113 and returned to the multiple etching solution nozzles 106 via the return pipe 112. Thus, the etching solution is circulated. On the other hand, if 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.

[0198] When the first etching solution (an etching solution containing the first compound) and the second etching solution (an etching solution containing the second compound) are supplied to the multiple substrates W held by the support frame 103, the first etching solution is supplied to the immersion tank 105 through multiple etching solution nozzles 106 with the drain valve 119 closed. After a predetermined time from the start of the supply of the first etching solution, the drain valve 119 is opened to drain the first etching solution from the immersion tank 105. Then, with the drain valve 119 closed, the second etching solution is supplied to the immersion tank 105 through the multiple etching solution nozzles 106.

[0199] Alternatively, instead of sequentially supplying the first and second etchants to a single immersion tank 105, an immersion tank 105 for storing the first etchant and another for storing the second etchant can be designed, and then multiple substrates W constituting a batch can be sequentially transferred into the two immersion tanks 105. This eliminates the need to replace the etchant in the immersion tank 105 with the second etchant.

[0200] The first and second etchants can also be mixed in the immersion tank 105. For example, the supply of the first etchant can be stopped after a predetermined time from the start of the supply, and then the supply of the second etchant can be started. In this case, the first and second etchants are mixed in the immersion tank 105, thereby changing the dissolved oxygen concentration of the etchant supplied to the substrate W.

[0201] Alternatively, instead of sequentially supplying the first and second etchants to the substrates W, the etchant can be initially supplied only to the immersion tank 105, and then the etchant in the immersion tank 105 can be mixed with at least one of a solution containing the first compound or a solution containing the second compound. In this case, the etchant without the compound is supplied to the multiple substrates W held by the support frame 103, and then the etchant containing the compound is supplied to the multiple substrates W held by the support frame 103.

[0202] [Other Implementation Methods]

[0203] The present invention is not limited to the aforementioned embodiments, and various modifications can be made.

[0204] For example, in the first embodiment, the etching solution may be supplied to the lower surface of the substrate W, rather than the upper surface. 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 spray the etching solution from the lower surface nozzle 15.

[0205] In the first embodiment, the first etchant and the second etchant can also be ejected from their respective nozzles, and the etchant, the solution containing the first compound, and the solution containing the second compound can also be ejected from their respective nozzles. In the latter case, at least two of the etchant, the solution containing the first compound, and the solution containing the second compound are mixed on the upper surface of the substrate W, or mixed in the space between the upper surface of the substrate W and the nozzle.

[0206] In the first embodiment, a first etching solution tank for storing the first etching solution and a second etching solution tank for storing the second etching solution can also be designed. In this case, the first etching solution and the second etching solution can be sprayed toward the substrate W from the same nozzle, or they can be sprayed toward the substrate W from their respective nozzles.

[0207] In the first embodiment, the first etchant on the substrate W may not be replaced by the second etchant. Instead, the first etchant on the substrate W may be replaced by a liquid other than the second etchant (intermediate liquid), and then the intermediate liquid on the substrate W may be replaced by the second etchant. Alternatively, two or more 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 by the first intermediate liquid, the first intermediate liquid on the substrate W may be replaced by the second intermediate liquid, and the second intermediate liquid on the substrate W may be replaced by the second etchant.

[0208] The cylindrical part 37 can also be omitted from the barrier member 33. The upper support part 43 and the lower support part 44 can also be omitted from the barrier member 33 and the rotating chuck 10.

[0209] Alternatively, the barrier 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 to spray the treatment liquid, such as the pharmaceutical solution, toward the substrate W. The nozzle can be a scanning nozzle that can move horizontally within the chamber 4, or it can be a fixed nozzle that is fixed relative to the partition wall 6 of the chamber 4. The nozzle can also have multiple liquid spray outlets that supply the treatment liquid to the upper or lower surface of the substrate W by simultaneously spraying the treatment liquid at multiple positions that are radially separated toward the substrate W. In this case, at least one of the flow rate, temperature, and concentration of the sprayed treatment liquid can be varied for each liquid spray outlet.

[0210] 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.

[0211] Two or more of the aforementioned components can also be combined. Two or more of the aforementioned steps can also be combined.

[0212] The rotary chuck 10 and support frame 103 are examples of a substrate holding unit. The processing liquid supply unit 61 is a first etching unit. The processing liquid supply unit 61 is also an example of a second etching unit.

[0213] The embodiments of the present invention will be described in detail, but these are merely specific examples used to illustrate the technical content of the present invention. The present invention should not be limited to these specific examples, and the spirit and scope of the present invention are limited only by the appended claims.

[0214] Explanation of reference numerals in the attached figures

[0215] 1: Substrate processing device

[0216] 10: Rotary chuck

[0217] 45: Center nozzle

[0218] 47: Etching solution spray outlet

[0219] 61: Processing fluid supply unit

[0220] 62: Etching solution tank

[0221] 70: Compound Tank No. 1

[0222] 75: Compound Tank No. 2

[0223] 91: Etched object

[0224] 92: convex part

[0225] 101: Substrate Processing Apparatus

[0226] 103: Support frame

[0227] 104: Etching Unit

[0228] W: substrate

Claims

1. A substrate processing method for processing a substrate containing an etched object representing at least one of monocrystalline silicon and polycrystalline silicon, comprising: The first etching step involves etching the object to be etched by supplying an alkaline first etching solution to the substrate. as well as In the second etching step, before or after the first etching solution is supplied to the substrate, an alkaline second etching solution is supplied to the substrate to etch the object to be etched. This second etching solution contains a compound that hinders the contact between hydroxide ions and the object to be etched. The difference between the maximum and minimum etching rates of the (110), (100), and (111) surfaces of the silicon is smaller than that of the first etching solution, and the maximum etching rate is smaller than that of the first etching solution. The first etching solution mentioned above is an alkaline etching solution containing the aforementioned compound; The first etching solution and the second etching solution are different from each other in at least one of the following: composition, concentration and temperature.

2. The substrate processing method as described in claim 1, wherein, The second etching step includes the step of replacing the first etching solution that is in contact with the substrate with the second etching solution by supplying the second etching solution to the substrate.

3. The substrate processing method as described in claim 1 or 2, wherein, The second etching step includes at least one of the following steps: mixing the compound into the first etching solution that is in contact with the substrate; and mixing the first etching solution into the compound-containing solution while the substrate is in contact with a compound-containing solution containing the compound.

4. A substrate processing method for processing a substrate containing an etched object representing at least one of monocrystalline silicon and polycrystalline silicon, comprising: The first etching step involves etching the object to be etched by supplying an alkaline first etching solution to the substrate. In the second etching step, before or after the first etching solution is supplied to the substrate, an alkaline second etching solution is supplied to the substrate to etch the object to be etched. This second etching solution contains a compound that hinders the contact between hydroxide ions and the object to be etched. The difference between the maximum and minimum etching rates of the (110), (100), and (111) surfaces of the silicon is smaller than that of the first etching solution, and the maximum etching rate is smaller than that of the first etching solution. The process involves repeating the first and second etching steps in one cycle multiple times.

5. A substrate processing apparatus for processing a substrate containing an etchable object representing at least one of monocrystalline silicon and polycrystalline silicon, comprising: A substrate holding unit holds the aforementioned substrate; The first etching unit etches the object to be etched by supplying an alkaline first etching solution to the substrate held by the substrate holding unit; and The second etching unit etches the object to be etched by supplying an alkaline second etching solution to the substrate held by the substrate holding unit before or after supplying the first etching solution to the substrate. The second etching solution contains a compound that hinders the contact between hydroxide ions and the object to be etched. The difference between the maximum and minimum etching rates of the (110), (100), and (111) surfaces of silicon is smaller than that of the first etching solution, and the maximum etching rate is smaller than that of the first etching solution. The first etching solution mentioned above is an alkaline etching solution containing the aforementioned compound; The first etching solution and the second etching solution are different from each other in at least one of the following: composition, concentration and temperature.

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