WO2020044789A1

WO2020044789A1 - Substrate processing method and substrate processing device

Info

Publication number: WO2020044789A1
Application number: PCT/JP2019/026609
Authority: WO
Inventors: 世根来; 小林　健司
Original assignee: 株式会社Ｓｃｒｅｅｎホールディングス
Priority date: 2018-08-31
Filing date: 2019-07-04
Publication date: 2020-03-05

Abstract

In the present invention, an alkaline etchant containing a quaternary ammonium hydroxide, water, and an inhibitory substance for inhibiting contact between hydroxide ions generated from the quaternary ammonium hydroxide and objects P1 to P3 to be etched is prepared. The prepared etchant is supplied to a substrate in which the polysilicon-containing objects P1 to P3 to be etched and objects O1 to O3 not to be etched, which are different from the objects P1 to P3 to be etched, are exposed, thereby etching the objects P1 to P3 to be etched while preventing the objects O1 to O3 not to be etched from being etched.

Description

Substrate processing method and substrate processing apparatus

This application claims priority based on Japanese Patent Application No. 2018-163796 filed on August 31, 2018 and Japanese Patent Application No. 2019-075345 filed on April 11, 2019. Is incorporated herein by reference in its entirety.

The present invention relates to a substrate processing method and a substrate processing apparatus for processing a substrate. The substrates to be processed include, for example, semiconductor wafers, flat panel display (FPD) substrates such as liquid crystal displays and organic EL (electroluminescence) displays, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, Substrates for masks, ceramic substrates, solar cells, and the like are included.

製造 In a manufacturing process of a semiconductor device or a liquid crystal display device, a substrate processing apparatus for processing a substrate such as a semiconductor wafer or a glass substrate for a liquid crystal display device is used. Patent Literature 1 discloses a substrate processing apparatus that supplies TMAH to a substrate and etches a polysilicon film formed on the substrate.

JP 2013-258391 A

In a manufacturing process of a semiconductor device or a liquid crystal display device, when an etching solution such as TMAH is supplied to a substrate where a polysilicon film and a silicon oxide film are exposed, the polysilicon film is etched while suppressing the etching of the silicon oxide film. There is. In this case, it is necessary to uniformly etch the polysilicon film while maintaining the selectivity (etching rate of polysilicon film / etching rate of silicon oxide film) at a high value.

The polysilicon film is composed of a large number of fine silicon single crystals. Silicon single crystals exhibit anisotropy with respect to TMAH. That is, the etching rate (etching amount per unit time) when TMAH is supplied to the silicon single crystal differs for each silicon crystal plane (etching anisotropy). The orientation of the crystal plane exposed on the surface of the polysilicon film is various, and differs for each location of the polysilicon film. In addition, the orientation of the crystal plane exposed on the surface of the polysilicon film differs for each polysilicon film.

の Since the silicon single crystal has anisotropy, if the polysilicon film is etched with TMAH, the etching amount of the polysilicon film is slightly different depending on the location of the polysilicon film. When a plurality of polysilicon films are etched by TMAH, the etching amount of the polysilicon film is slightly different for each polysilicon film. With the miniaturization of the pattern formed on the substrate, such non-uniform etching may not be allowed.

Therefore, an object of the present invention is to provide a substrate processing method and a substrate processing apparatus capable of uniformly etching an etching target including polysilicon while suppressing etching of a non-etching target different from silicon single crystal or polysilicon. To provide.

One embodiment of the present invention is a substrate processing method for supplying an alkaline etching solution to a substrate on which an etching target including polysilicon and a non-etching target different from the etching target are exposed, Forming an alkaline etchant comprising a quaternary ammonium hydroxide, water, and an inhibitor that inhibits contact between the hydroxide ion generated from the quaternary ammonium hydroxide and the object to be etched; Etching the non-etching target object by supplying the etching liquid prepared in the etching liquid preparing step to the substrate where the etching target and the non-etching target are exposed. A selective etching step of etching the object to be etched while suppressing etching. That.

According to this configuration, an alkaline etching solution containing a quaternary ammonium hydroxide, water, and an inhibitor is applied to a substrate on which an etching target including polysilicon and a non-etching target different from the etching target are exposed. To supply. When the quaternary ammonium hydroxide is dissolved in water, the quaternary ammonium hydroxide separates into cations (cations) and hydroxide ions. The silicon single crystal contained in the etching target reacts with hydroxide ions and is dissolved in the etching solution. The etching rate of the etching target is higher than the etching rate of the non-etching target. Thereby, the etching target is selectively etched.

(4) The inhibitor inhibits contact between the hydroxide ion and the object to be etched. That is, the inhibitor acts as a three-dimensional barrier for hydroxide ions, and reduces the number of hydroxide ions that react with the etching target. Thereby, the etching rate of the etching target decreases. Further, the etching rate does not decrease uniformly on a plurality of crystal planes of the silicon single crystal, but relatively decreases on a crystal plane having a high etching rate among them. As a result, the difference between the etching rates in the plurality of crystal planes decreases, and the anisotropy of the silicon single crystal with respect to the etching solution decreases. That is, the etching of the silicon single crystal included in the etching object approaches the isotropic etching, and the etching object is etched with a uniform etching amount in any place.

エッチング The object to be etched may be a part of the substrate itself, or may be a part or all of a laminate formed on the substrate (a base material such as a silicon wafer). If the etching conditions such as the orientation of the crystal plane and the temperature are the same, the etching rate of the silicon single crystal when the alkaline etching solution containing the quaternary ammonium hydroxide, the water and the inhibitor is supplied, And an etching rate of a silicon single crystal when an alkaline etching solution containing the quaternary ammonium hydroxide and the water and not containing the inhibitor is supplied.

In the above embodiment, at least one of the following features may be added to the substrate processing method.

The etching solution forming step includes a concentration determining step of determining a concentration of the inhibitor in the etching solution based on a difference between etching rates on a plurality of crystal planes of the silicon single crystal constituting the polysilicon.

(4) The concentration of the inhibitor in the etching solution prepared in the etching solution forming step is not less than 20% by mass and less than 100% by mass.

分子 The molecule of the inhibitor is larger than the hydroxide ion.

よう As described above, hydroxide ions in the etching solution are blocked by the inhibitor in the etching solution. If the number of molecules of the inhibitor present in the etching solution is the same, the larger the molecule of the inhibitor, the more difficult it is for hydroxide ions to reach the etching target. When an inhibitor having one molecule larger than hydroxide ions is used as in this configuration, the number of hydroxide ions in contact with the etching target can be effectively reduced.

The etching liquid forming step includes a pre-discharge mixing step of mixing the quaternary ammonium hydroxide, the water, and the inhibitor before the etching liquid is discharged from a discharge port, and the selective etching step Includes an ejection step of ejecting the etching solution created in the etching solution creation step toward the substrate through the ejection port.

According to this configuration, the quaternary ammonium hydroxide, water, and the inhibitor are mixed not before being discharged from the discharge port but before being discharged from the discharge port. As a result, an etching solution is prepared in which the quaternary ammonium hydroxide, water, and the inhibitor are uniformly mixed. Thereafter, the etchant is discharged from the discharge port toward the substrate, and is supplied to the substrate. Therefore, the substrate can be treated more uniformly than in the case where the quaternary ammonium hydroxide, water, and the inhibitor are mixed after being discharged from the discharge port.

The pre-discharge mixing step may be an in-tank mixing step of mixing the quaternary ammonium hydroxide, the water, and the inhibitor in a tank connected to the discharge port via a pipe. Then, an in-flow channel mixing step of mixing the quaternary ammonium hydroxide, the water, and the inhibitor in a flow channel (pipe or nozzle) for guiding the liquid toward the discharge port may be employed. . The etching liquid forming step is an aerial mixing step of mixing the quaternary ammonium hydroxide, the water, and the inhibitor in a space between the discharge port and the substrate instead of the pre-discharge mixing step. And a mixing step on a substrate for mixing the quaternary ammonium hydroxide, the water and the inhibitor on the substrate.

The substrate processing method further includes, before the selective etching step, a natural oxide film removing step of supplying an oxide film removing solution to the substrate to remove a natural oxide film of the object to be etched.

According to this configuration, the oxide film removing liquid is supplied to the substrate, and the natural oxide film of the etching target is removed from the surface layer of the etching target. Thereafter, an etching solution is supplied to the substrate, and the object to be etched is selectively etched. The natural oxide film to be etched is mainly composed of silicon oxide. The etchant is a liquid that etches an etching target with little or no etching of silicon oxide. This is because hydroxide ions react with silicon, but do not or rarely react with silicon oxide. Therefore, the etching target can be efficiently etched by removing the natural oxide film of the etching target in advance.

The etching target is a thin film obtained by performing a plurality of steps including a deposition step of depositing polysilicon and a heat treatment step of heating the polysilicon deposited in the deposition step.

According to this configuration, the etching target that has been subjected to the heat treatment step of heating the deposited polysilicon is etched with an alkaline etchant. Heating the deposited polysilicon under appropriate conditions increases the polysilicon grain size. Therefore, the size of the silicon single crystal included in the etching target is increased as compared with the case where the heat treatment step is not performed. This means that the number of silicon single crystals exposed on the surface of the etching target decreases, and the influence of anisotropy increases. Therefore, by supplying an etching solution containing a quaternary ammonium hydroxide, water, and an inhibitor to such an etching target, the influence of anisotropy can be effectively reduced.

The etching solution forming step includes a dissolved oxygen concentration changing step of reducing a dissolved oxygen concentration of at least one of the quaternary ammonium hydroxide, the water, and the inhibitor.

According to this configuration, the dissolved oxygen concentration of at least one of the quaternary ammonium hydroxide, water, and the inhibitor is reduced. Accordingly, the concentration of dissolved oxygen in the etching solution prepared from these decreases. When an etching solution having a high dissolved oxygen concentration is supplied to the substrate, a part of the surface layer of the etching target is oxidized and changes to silicon oxide. This means that the etching rate of the object to be etched is further reduced. Therefore, by supplying an etchant having a low dissolved oxygen concentration to the substrate, it is possible to reduce the anisotropy of the silicon single crystal while suppressing a decrease in the etching rate of the etching target.

In the dissolved oxygen concentration changing step, at least one of the quaternary ammonium hydroxide, the water, and the inhibitor is lower than an oxygen concentration in air (about 21 vol% (volume percent concentration)). It may be a gas dissolving step of dissolving a low oxygen gas having an oxygen concentration, or the pressure in a tank for storing at least one of the quaternary ammonium hydroxide, the water, and the inhibitor. It may be a step other than the gas dissolving step, such as a pressure reducing step for lowering the pressure.

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

According to this configuration, the etchant is supplied to the substrate in a state where the oxygen concentration in the atmosphere is low. This reduces the amount of oxygen dissolved from the atmosphere into the etching solution, thereby suppressing an increase in the concentration of dissolved oxygen. When an etching solution having a high dissolved oxygen concentration is supplied to the substrate, the etching rate of the object to be etched is further reduced. Therefore, a further decrease in the etching rate can be suppressed by reducing the oxygen concentration in the atmosphere.

The inhibitor is glycol.

The etching solution forming step is a step of forming the alkaline etching solution containing TMAH (tetramethylammonium hydroxide) as the quaternary ammonium hydroxide, the water, and propylene glycol as the glycol. It is.

Another embodiment of the present invention is a substrate processing apparatus that supplies an alkaline etchant to an exposed substrate, including an etching target including polysilicon and a non-etching target different from the etching target, The alkaline etching solution containing a quaternary ammonium hydroxide, water, and an inhibitor that inhibits contact between the hydroxide ion generated from the quaternary ammonium hydroxide and the object to be etched. Etching liquid to be created, and the etching liquid created by the etching liquid creating means is supplied to the substrate where the etching target and the non-etching target are exposed, thereby etching the non-etching target. And a selective etching means for etching the object to be etched while suppressing the etching. That. According to this configuration, the same effect as the above-described effect can be obtained.

In the above embodiment, at least one of the following features may be added to the substrate processing apparatus.

The etching solution preparing means includes a concentration determining means for determining a concentration of the inhibitor in the etching solution based on a difference in etching rate between a plurality of crystal planes of the silicon single crystal constituting the polysilicon.

濃度 The concentration of the inhibitor in the etching solution prepared by the etching solution preparation means is not less than 20% by mass and less than 100% by mass.

分子 The molecule of the inhibitor is larger than the hydroxide ion. According to this configuration, the same effect as the above-described effect can be obtained.

The selective etching means includes a discharge port for discharging the etchant created by the etchant creation means toward the substrate, and the etching solution creation means includes a step before the etchant is discharged from the discharge port. And mixing means for mixing the quaternary ammonium hydroxide, the water and the inhibitor. According to this configuration, the same effect as the above-described effect can be obtained.

The substrate processing apparatus supplies an oxide film removing solution to the substrate before the etching solution created by the etching solution creating unit is supplied to the substrate, and removes a natural oxide film of the etching target. It further includes a natural oxide film removing means. According to this configuration, the same effect as the above-described effect can be obtained.

The etching solution preparing means includes a dissolved oxygen concentration changing means for lowering a dissolved oxygen concentration of at least one of the quaternary ammonium hydroxide, the water and the inhibitor. According to this configuration, the same effect as the above-described effect can be obtained.

The substrate processing apparatus further includes an atmosphere oxygen concentration changing unit that reduces an oxygen concentration in an atmosphere in contact with the etching solution held on the substrate. According to this configuration, the same effect as the above-described effect can be obtained.

The inhibitor is glycol.

The etching solution preparing means includes means for preparing the alkaline etching solution containing TMAH (tetramethylammonium hydroxide) as the quaternary ammonium hydroxide, the water, and propylene glycol as the glycol. It is.

The above or other objects, features, and effects of the present invention will be apparent from the following description of embodiments with reference to the accompanying drawings.

FIG. 1 is a schematic view of a substrate processing apparatus according to a first embodiment of the present invention as viewed from above. It is the schematic diagram which looked at the substrate processing apparatus from the side. FIG. 3 is a schematic view of the inside of a processing unit provided in the substrate processing apparatus as viewed horizontally. FIG. 3 is an enlarged view in which a part of FIG. 2 is enlarged. It is a schematic diagram which shows the chemical | medical solution preparation unit which produces | generates the chemical | medical solution supplied to a board | substrate, and the dissolved oxygen concentration change unit which adjusts the dissolved oxygen concentration of a chemical | medical solution. FIG. 3 is a block diagram illustrating hardware of a control device. FIG. 8 is a schematic diagram illustrating an example of a cross section of the substrate before and after the processing illustrated in FIG. 7 is performed. It is a flowchart for explaining an example of substrate processing performed by a substrate processing device. It is a figure for explaining a mechanism assumed when contact between hydroxide ion and polysilicon is inhibited by an inhibitor. It is a figure for explaining a mechanism assumed when contact between hydroxide ion and polysilicon is inhibited by an inhibitor. 4 is a graph showing an example of a relationship between an etching rate of three crystal planes of a silicon single crystal and a concentration of propylene glycol in an etching solution. FIG. 9 is a schematic diagram illustrating a chemical solution processing unit provided in a substrate processing apparatus according to a second embodiment of the present invention. FIG. 3 is a process diagram showing an example of a flow from creation of a new etching solution to discharge of a used etching solution from an immersion tank. It is a schematic diagram which shows the chemical | medical solution preparation unit which concerns on 3rd Embodiment of this invention.

FIG. 1A is a schematic view of the substrate processing apparatus 1 according to the first embodiment of the present invention as viewed from above. FIG. 1B is a schematic view of the substrate processing apparatus 1 as viewed from the side.

As shown in FIG. 1A, the substrate processing apparatus 1 is a single-wafer processing apparatus that processes a disk-shaped substrate W such as a semiconductor wafer one by one. The substrate processing apparatus 1 includes a load port LP that holds a carrier C containing a substrate W, a plurality of processing units 2 that process the substrate W transported from the carrier C on the load port LP, and a carrier on the load port LP. A transfer robot that transfers the substrate W between C and the processing unit 2 and a control device 3 that controls the substrate processing apparatus 1 are provided.

The transfer robot includes an indexer robot IR for loading and unloading the substrate W to and from the carrier C on the load port LP, and a center robot CR for loading and unloading the substrate W to and from the plurality of processing units 2. The indexer robot IR transports the substrate W between the load port LP and the center robot CR, and the center robot CR transports the substrate W between the indexer robot IR and the processing unit 2. The center robot CR includes a hand H1 that supports the substrate W, and the indexer robot IR includes a hand H2 that supports the substrate W.

(4) The plurality of processing units 2 form a plurality of towers TW arranged around the center robot CR in plan view. FIG. 1A shows an example in which four towers TW are formed. The center robot CR can access any of the towers TW. As shown in FIG. 1B, each tower TW includes a plurality (for example, three) of processing units 2 stacked vertically.

FIG. 2 is a schematic view of the inside of the processing unit 2 provided in the substrate processing apparatus 1 as viewed horizontally. FIG. 3 is an enlarged view in which a part of FIG. 2 is enlarged. FIG. 2 shows a state in which the lifting frame 32 and the blocking member 33 are located at the lower position, and FIG. 3 shows a state in which the lifting frame 32 and the blocking member 33 are located at the upper position. In the following description, TMAH means an aqueous solution of TMAH unless otherwise specified.

The processing unit 2 includes a box-shaped chamber 4 having an internal space, and a spin chuck 10 that rotates around a vertical rotation axis A1 passing through the center of the substrate W while horizontally holding one substrate W in the chamber 4. And a cylindrical processing cup 23 surrounding the spin chuck 10 around the rotation axis A1.

The chamber 4 includes a box-shaped partition wall 6 provided with a loading / unloading port 6b through which the substrate W passes, and a shutter 7 for opening and closing the loading / unloading port 6b. The chamber 4 further includes a rectifying plate 8 disposed below an air blow port 6 a opened on the ceiling surface of the partition wall 6. An FFU 5 (fan filter unit) that sends clean air (air filtered by a filter) is disposed above the air outlet 6a. The exhaust duct 9 for discharging the gas in the chamber 4 is connected to the processing cup 23. The air outlet 6 a is provided at the upper end of the chamber 4, and the exhaust duct 9 is arranged at the lower end of the chamber 4. Part of the exhaust duct 9 is arranged outside the chamber 4.

The rectifying plate 8 partitions the internal space of the partition 6 into an upper space Su above the rectifying plate 8 and a lower space SL below the rectifying plate 8. The upper space Su between the ceiling surface of the partition 6 and the upper surface of the current plate 8 is a diffusion space in which clean air is diffused. The lower space SL between the lower surface of the current plate 8 and the floor surface of the partition 6 is a processing space in which processing of the substrate W is performed. The spin chuck 10 and the processing cup 23 are arranged in the lower space SL. The vertical distance from the floor surface of the partition 6 to the lower surface of the current plate 8 is longer than the vertical distance from the upper surface of the current plate 8 to the ceiling surface of the partition 6.

The FFU 5 sends clean air to the upper space Su via the air outlet 6a. The clean air supplied to the upper space Su strikes the current plate 8 and diffuses in the upper space Su. The clean air in the upper space Su passes through a plurality of through holes vertically penetrating the current plate 8 and flows downward from the entire area of the current plate 8. 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. As a result, a uniform downward flow (downflow) of clean air flowing downward from the current plate 8 is formed in the lower space SL. The processing of the substrate W is performed in a state where a downward flow of clean air is formed.

The spin chuck 10 includes a disk-shaped spin base 12 held in a horizontal position, a plurality of chuck pins 11 for holding the substrate W in a horizontal position above the spin base 12, and a central portion of the spin base 12. It includes a spin shaft 13 extending downward, and a spin motor 14 that rotates the spin base 12 and the plurality of chuck pins 11 by rotating the spin shaft 13. The spin chuck 10 is not limited to a sandwich type chuck in which the plurality of chuck pins 11 are brought into contact with the outer peripheral surface of the substrate W, and causes the back surface (lower surface) of the substrate W, which is a non-device formation surface, to be attracted to the upper surface 12 u of the spin base 12. Thus, a vacuum-type chuck that holds the substrate W horizontally may be used.

The spin base 12 includes an upper surface 12u arranged below the substrate W. The upper surface 12u of the spin base 12 is parallel to the lower surface of the substrate W. The upper surface 12u of the spin base 12 is a facing surface facing the lower surface of the substrate W. The upper surface 12u of the spin base 12 has an annular shape surrounding the rotation axis A1. The outer diameter of the upper surface 12u of the spin base 12 is larger than the outer diameter of the substrate W. The chuck pin 11 protrudes upward from the outer peripheral portion of the upper surface 12u of the spin base 12. The chuck pin 11 is held on a spin base 12. The substrate W is held by the plurality of chuck pins 11 with the lower surface of the substrate W separated from the upper surface 12u of the spin base 12.

The processing unit 2 includes the lower surface nozzle 15 that discharges the processing liquid toward the center of the lower surface of the substrate W. The lower surface nozzle 15 includes a nozzle disk portion disposed between the upper surface 12u of the spin base 12 and the lower surface of the substrate W, and a nozzle cylindrical portion extending downward from the nozzle disk portion. The liquid discharge port 15p of the lower surface nozzle 15 is open at the center of the upper surface of the nozzle disk portion. In a state where the substrate W is held by the spin chuck 10, the liquid discharge port 15p of the lower surface nozzle 15 is vertically opposed to the center of the lower surface of the substrate W.

The substrate processing apparatus 1 includes a lower rinsing liquid pipe 16 for guiding the rinsing liquid to the lower surface nozzle 15, and a lower rinsing liquid valve 17 interposed in the lower rinsing liquid pipe 16. When the lower rinsing liquid valve 17 is opened, the rinsing liquid guided by the lower rinsing liquid pipe 16 is discharged upward from the lower nozzle 15 and supplied to the center of the lower surface of the substrate W. The rinsing liquid supplied to the lower nozzle 15 is pure water (deionized water: DIW (Deionized Water)). The rinsing liquid supplied to the lower surface nozzle 15 is not limited to pure water, but may be IPA (isopropyl alcohol), carbonated water, electrolytic ionic water, hydrogen water, ozone water, and hydrochloric acid water having a dilute concentration (for example, about 1 to 100 ppm). May be any of

Although not shown, the lower rinsing liquid valve 17 includes a valve body provided with an internal flow path through which liquid flows and an annular valve seat surrounding the internal flow path, a valve body movable with respect to the valve seat, and a valve. An actuator for moving the valve body between a closed position where the body contacts the valve seat and an open position where the valve body is away from the valve seat. The same applies to other valves. The actuator may be a pneumatic actuator or an electric actuator, or may be another actuator. The control device 3 opens and closes the lower rinse liquid valve 17 by controlling the actuator.

外周 An outer peripheral surface of the lower nozzle 15 and an inner peripheral surface of the spin base 12 form a lower tubular 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 spin base 12. The lower center opening 18 is arranged below the nozzle disk portion of the lower surface nozzle 15. The substrate processing apparatus 1 includes: a lower gas pipe 20 that guides an inert gas supplied to the lower central opening 18 through a lower cylindrical passage 19; a lower gas valve 21 interposed in the lower gas pipe 20; A lower gas flow control valve 22 for changing the flow rate of the inert gas supplied from the pipe 20 to the lower cylindrical passage 19 is provided.

不 The inert gas supplied from the lower gas pipe 20 to the lower cylindrical passage 19 is a nitrogen gas. The inert gas is not limited to nitrogen gas, but may be another inert gas such as helium gas or argon gas. These inert gases are low oxygen gases having an oxygen concentration lower than the oxygen concentration in air (about 21 vol%).

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

The processing cup 23 includes a plurality of guards 25 for receiving the liquid discharged outward from the substrate W, a plurality of cups 26 for receiving the liquid guided downward by the plurality of guards 25, a plurality of guards 25, and a plurality of cups. 26 and a cylindrical outer wall member 24 surrounding the outer wall member 24. FIG. 2 shows an example in which two guards 25 and two cups 26 are provided.

The guard 25 includes a cylindrical guard tubular portion 25b surrounding the spin chuck 10, and an annular guard ceiling 25a extending obliquely upward from the upper end of the guard tubular portion 25b toward the rotation axis A1. The plurality of guard ceiling portions 25a are vertically overlapped, and the plurality of guard tubular portions 25b are arranged concentrically. The plurality of cups 26 are respectively arranged below the plurality of guard tubular portions 25b. The cup 26 forms an annular liquid receiving groove that opens upward.

The processing unit 2 includes a guard elevating unit 27 for individually elevating and lowering a plurality of guards 25. The guard elevating unit 27 positions the guard 25 at an arbitrary position from the upper position to the lower position. The upper position is a position where the upper end 25u of the guard 25 is located above the holding position where the substrate W held by the spin chuck 10 is located. The lower position is a position where the upper end 25u of the guard 25 is disposed below the holding position. The annular upper end of the guard ceiling 25a corresponds to the upper end 25u of the guard 25. The upper end 25u of the guard 25 surrounds the substrate W and the spin base 12 in plan view.

(4) When the processing liquid is supplied to the substrate W while the spin chuck 10 is rotating the substrate W, the processing liquid supplied to the substrate W is shaken off from the substrate W. When the processing liquid is supplied to the substrate W, the upper end 25u of at least one guard 25 is disposed above the substrate W. Therefore, the processing liquid such as the chemical liquid or the rinsing liquid discharged from the substrate W is received by any of the guards 25 and guided to the cup 26 corresponding to the guard 25.

As shown in FIG. 3, the processing unit 2 includes a lifting frame 32 disposed above the spin chuck 10, a blocking member 33 suspended from the lifting frame 32, and a central nozzle 45 inserted into the blocking member 33. And a blocking member elevating unit 31 that raises and lowers the lifting frame 32 to raise and lower the blocking member 33 and the center nozzle 45. The lifting frame 32, the blocking member 33, and the center nozzle 45 are arranged below the current plate 8.

The blocking member 33 includes a disk portion 36 disposed above the spin chuck 10 and a cylindrical portion 37 extending downward from the outer peripheral portion of the disk portion 36. The blocking member 33 includes an upwardly concave cup-shaped inner surface. The inner surface of the blocking member 33 includes a lower surface 36L of the disk portion 36 and an inner peripheral surface 37i of the cylindrical portion 37. Hereinafter, the lower surface 36L of the disk portion 36 may be referred to as the lower surface 36L of the blocking member 33.

下面 A lower surface 36L of the disk portion 36 is a facing surface facing the upper surface of the substrate W. The lower surface 36L of the disk 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 disk portion 36. The inner diameter of the cylindrical portion 37 increases as approaching 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 be larger than the outer diameter of the spin base 12. When the blocking member 33 is arranged at a lower position (a position shown in FIG. 2) described later, the substrate W is surrounded by the inner peripheral surface 37i of the tubular portion 37.

下面 A lower surface 36L of the disk portion 36 is an annular shape surrounding the rotation axis A1. The inner peripheral edge of the lower surface 36L of the disk portion 36 forms an upper central opening 38 that opens at the center of the lower surface 36L of the disk portion 36. The inner peripheral surface of the blocking member 33 forms a through hole extending upward from the upper central opening 38. The through hole of the blocking member 33 penetrates the blocking member 33 up and down. The center nozzle 45 is inserted into a through hole of the blocking member 33. The outer diameter of the lower end of the center nozzle 45 is smaller than the diameter of the upper center opening 38.

内 The inner peripheral surface of the blocking member 33 is coaxial with the outer peripheral surface of the central nozzle 45. The inner peripheral surface of the blocking member 33 surrounds the outer peripheral surface of the central nozzle 45 at intervals in a radial direction (a direction orthogonal to the rotation axis A1). The inner peripheral surface of the blocking member 33 and the outer peripheral surface of the central nozzle 45 form an upper cylindrical passage 39 extending vertically. The center nozzle 45 protrudes upward from the lifting frame 32 and the blocking member 33. When the blocking member 33 is suspended from the lifting frame 32, the lower end of the center nozzle 45 is disposed above the lower surface 36 </ b> L of the disk portion 36. A processing liquid such as a chemical liquid or a rinsing liquid is discharged downward from the lower end of the central nozzle 45.

The blocking member 33 includes a cylindrical connecting portion 35 extending upward from the disk portion 36 and an annular flange portion 34 extending outward from the upper end of the connecting portion 35. The flange portion 34 is disposed above the disk portion 36 and the cylindrical portion 37 of the blocking member 33. The flange 34 is parallel to the disk 36. The outer diameter of the flange portion 34 is smaller than the outer diameter of the cylindrical portion 37. The flange portion 34 is supported by a lower plate 32L of the lifting frame 32 described later.

The elevating frame 32 includes an upper plate 32 u located above the flange portion 34 of the blocking member 33, a downward extending from the upper plate 32 u, a side ring 32 s surrounding the flange portion 34, and an inner side extending from the lower end of the side ring 32 s. And an annular lower plate 32L positioned below the flange portion 34 of the blocking member 33. The outer peripheral portion of the flange portion 34 is disposed between the upper plate 32u and the lower plate 32L. The outer peripheral portion of the flange portion 34 is vertically movable between the upper plate 32u and the lower plate 32L.

The lifting frame 32 and the blocking member 33 are positioned to restrict the relative movement of the lifting frame 32 and the blocking member 33 in the circumferential direction (direction around the rotation axis A1) in a state where the blocking member 33 is supported by the lifting frame 32. It includes a projection 41 and a positioning hole 42. FIG. 2 shows an example in which a plurality of positioning projections 41 are provided on the lower plate 32L, and a plurality of positioning holes 42 are provided on the flange portion 34. The positioning projection 41 may be provided on the flange portion 34, and the positioning hole 42 may be provided on the lower plate 32L.

The plurality of positioning protrusions 41 are arranged on a circle having a center arranged on the rotation axis A1. Similarly, the plurality of positioning holes 42 are arranged on a circle having a center located on the rotation axis A1. The plurality of positioning holes 42 are arranged in the circumferential direction with the same regularity as the plurality of positioning protrusions 41. The positioning protrusion 41 projecting upward from the upper surface of the lower plate 32L is inserted into a positioning hole 42 extending upward from the lower surface of the flange portion 34. Thereby, the movement of the blocking member 33 in the circumferential direction with respect to the lifting frame 32 is restricted.

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

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

The blocking member elevating unit 31 is connected to the elevating frame 32. When the blocking member lifting / lowering unit 31 lowers the lifting frame 32 in a state where the flange portion 34 of the blocking member 33 is supported by the lower plate 32L of the lifting frame 32, the blocking member 33 also moves down. When the shut-off member elevating unit 31 lowers the shut-off member 33 in a state where the spin base 12 is arranged at a reference rotation angle at which the plurality of upper support portions 43 respectively overlap the lower support portions 44 in plan view, the upper support The lower end of the part 43 contacts the upper end of the lower support part 44. Thereby, the plurality of upper support portions 43 are supported by the plurality of lower support portions 44, respectively.

After the upper supporting portion 43 of the blocking member 33 contacts the lower supporting portion 44 of the spin chuck 10 and the blocking member lifting / lowering unit 31 lowers the lifting frame 32, the lower plate 32 </ b> L of the lifting frame 32 moves to the flange portion of the blocking member 33. It moves downward with respect to 34. As a result, the lower plate 32L separates from the flange portion 34, and the positioning projection 41 comes out of the positioning hole 42. Furthermore, since the lifting frame 32 and the center nozzle 45 move downward with respect to the blocking member 33, the height difference between the lower end of the center nozzle 45 and the lower surface 36L of the disk portion 36 of the blocking member 33 is reduced. At this time, the lifting frame 32 is disposed at a height (a lower position described later) at which the flange portion 34 of the blocking member 33 does not contact the upper plate 32 u of the lifting frame 32.

The blocking member elevating unit 31 positions the elevating frame 32 at an arbitrary position from the upper position (the position shown in FIG. 3) to the lower position (the position shown in FIG. 2). The upper position is a position where the positioning projection 41 is inserted into the positioning hole 42 and the flange portion 34 of the blocking member 33 is in contact with the lower plate 32L of the lifting frame 32. That is, the upper position is a position where the blocking member 33 is suspended from the lifting frame 32. The lower position is a position where the lower plate 32L is separated from the flange portion 34 and the positioning protrusion 41 comes out of the positioning hole 42. That is, the lower position is a position where the connection between the lifting frame 32 and the blocking member 33 is released, and the blocking member 33 does not contact any part of the lifting frame 32.

When the lifting frame 32 and the blocking member 33 are moved to the lower position, the lower end of the cylindrical portion 37 of the blocking member 33 is disposed below the lower surface of the substrate W, and the upper surface of the substrate W and the lower surface 36L of the blocking member 33 are connected. The space therebetween is surrounded by the cylindrical portion 37 of the blocking member 33. Therefore, the space between the upper surface of the substrate W and the lower surface 36L of the blocking member 33 is shielded from not only the atmosphere above the blocking member 33 but also the atmosphere around the blocking member 33. Thereby, the degree of sealing of the space between the upper surface of the substrate W and the lower surface 36L of the blocking member 33 can be increased.

Further, when the lifting frame 32 and the blocking member 33 are arranged at the lower position, the blocking member 33 does not collide with the lifting frame 32 even if the blocking member 33 is rotated around the rotation axis A1 with respect to the lifting frame 32. When the upper support portion 43 of the blocking member 33 is supported by the lower support portion 44 of the spin chuck 10, the upper support portion 43 and the lower support portion 44 mesh with each other, and the relative positions of the upper support portion 43 and the lower support portion 44 in the circumferential direction. Movement is regulated. When the spin motor 14 rotates in this state, the torque of the spin motor 14 is transmitted to the blocking member 33 via the upper support 43 and the lower support 44. Thus, the blocking member 33 rotates at the same speed in the same direction as the spin base 12 with the lifting frame 32 and the center nozzle 45 stationary.

The center nozzle 45 includes a plurality of liquid discharge ports for discharging liquid and gas discharge ports for discharging gas. The plurality of liquid discharge ports include a first chemical liquid discharge port 46 for discharging a first chemical liquid, a second chemical liquid discharge port 47 for discharging a second chemical liquid, and an upper rinse liquid discharge port 48 for discharging a rinse liquid. The gas discharge port is an upper gas discharge port 49 for discharging an inert gas. The first chemical liquid discharge port 46, the second chemical liquid discharge port 47, and the upper rinse liquid discharge port 48 are open at the lower end of the center nozzle 45. The upper gas discharge port 49 is open on the outer peripheral surface of the center nozzle 45.

The first and second chemicals include, for example, sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, acetic acid, aqueous ammonia, aqueous hydrogen peroxide, organic acids (for example, citric acid, oxalic acid, etc.), and organic alkalis (for example, TMAH: Liquid containing at least one of tetramethylammonium hydroxide, a surfactant, a polyhydric alcohol, and a corrosion inhibitor. Sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, acetic acid, aqueous ammonia, aqueous hydrogen peroxide, citric acid, oxalic acid, and TMAH are etching solutions.

The first chemical solution and the second chemical solution may be the same type of chemical solution or different types of chemical solutions. FIG. 2 and the like show an example in which the first chemical is DHF (dilute hydrofluoric acid) and the second chemical is a mixture of TMAH and propylene glycol. 2 and the like show an example in which the rinsing liquid supplied to the central nozzle 45 is pure water, and the inert gas supplied to the central nozzle 45 is nitrogen gas. The rinsing liquid supplied to the center nozzle 45 may be a rinsing liquid other than pure water. The inert gas supplied to the center nozzle 45 may be an inert gas other than the nitrogen gas.

The substrate processing apparatus 1 includes a chemical solution preparation unit 61 for preparing an alkaline etching solution corresponding to the second chemical solution. The etching solution is, for example, a liquid having a pH (hydrogen ion index) of 12 or more. The etching solution is a solution containing a quaternary ammonium hydroxide, water (H2O), and an inhibitor. FIG. 2 and the like show an example in which the quaternary ammonium hydroxide is TMAH and the inhibitor is PG (propylene glycol). If the oxidizing agent is not an oxidizing agent that oxidizes the surface of the substrate W (the surface of the base material) or the surface of the stacked body formed on the substrate W, the etching solution is not quaternary ammonium hydroxide, water, and an inhibitor. It may further contain a substance.

The quaternary ammonium hydroxides are TMAH, TBAH (tetrabutylammonium hydroxide), TPeAH (tetrapentylammonium hydroxide), THAH (tetrahexylammonium hydroxide), TEAH (tetraethylammonium hydroxide), and TPAH (tetraethylammonium hydroxide). Propylammonium hydroxide), or may be other than these. These are all included in the organic alkali. In this paragraph, TMAH is not an aqueous solution but an anhydride. This is the same for other quaternary ammonium hydroxides such as TBAH.

と When the quaternary ammonium hydroxide is dissolved in water, the quaternary ammonium hydroxide separates into cations (cations) and hydroxide ions. The inhibitor is a substance that inhibits contact between hydroxide ions generated from the quaternary ammonium hydroxide and an etching target including polysilicon. Preferably, the inhibitor molecule is larger than the hydroxide ion. Further, the inhibitor is preferably a water-soluble substance that is soluble in water. The inhibitor may be a surfactant having both hydrophilic and hydrophobic groups. The inhibitor may be an insoluble substance that does not dissolve in water as long as it is uniformly dispersed in a solution containing a quaternary ammonium hydroxide and water.

The inhibitor is, for example, glycol. The glycol is, for example, at least one of ethylene glycol, diethylene glycol and propylene glycol. The inhibitor may be a substance other than glycol, such as glycerin. Glycol is an example of a substance that does not participate in the reaction between silicon (Si) and hydroxide ions (OH ⁻ ). That is, glycol is an example of a substance that does not react with atoms or the like involved in the reaction between silicon and hydroxide ions. Glycol is an example of a substance that does not act as a catalyst in this reaction. Preferably, the glycol is propylene glycol.

The substrate processing apparatus 1 guides the first chemical liquid to the central nozzle 45, the first chemical liquid valve 51 interposed in the first chemical liquid pipe 50, and guides the second chemical liquid to the central nozzle 45. A second chemical liquid pipe 52, a second chemical liquid valve 53 interposed in the second chemical liquid pipe 52, an upper rinse liquid pipe 54 for guiding the rinse liquid to the center nozzle 45, and an upper rinse liquid pipe 54 An upper rinse liquid valve 55 is provided. The substrate processing apparatus 1 further includes an upper gas pipe 56 for guiding a gas to the center nozzle 45, an upper gas valve 57 interposed in the upper gas pipe 56, and a gas supplied from the upper gas pipe 56 to the center nozzle 45. An upper gas flow control valve 58 for changing the flow rate is provided.

When the first chemical liquid valve 51 is opened, the first chemical liquid is supplied to the central nozzle 45 and is discharged downward from the first chemical liquid discharge port 46 opened at the lower end of the central nozzle 45. When the second chemical liquid valve 53 is opened, the second chemical liquid generated by the chemical liquid preparation unit 61 is supplied to the central nozzle 45 and is discharged downward from the second chemical liquid discharge port 47 opened at the lower end of the central nozzle 45. When the upper rinsing liquid valve 55 is opened, the rinsing liquid is supplied to the center nozzle 45 and discharged downward from the upper rinsing liquid discharge port 48 opened at the lower end of the center nozzle 45. Thereby, the chemical solution or the rinsing liquid is supplied to the upper surface of the substrate W.

When the upper gas valve 57 is opened, the nitrogen gas guided by the upper gas pipe 56 is supplied to the center nozzle 45 at a flow rate corresponding to the degree of opening of the upper gas flow rate adjustment valve 58, and is opened at the outer peripheral surface of the center nozzle 45. The gas is discharged obliquely downward from the upper gas discharge port 49. Thereafter, the nitrogen gas flows downward in the upper cylindrical passage 39 while flowing in the upper cylindrical passage 39 in the circumferential direction. The nitrogen gas that has reached the lower end of the upper tubular passage 39 flows downward from the lower end of the upper tubular passage 39. Thereafter, the nitrogen gas flows radially in all directions in the space between the upper surface of the substrate W and the lower surface 36L of the blocking member 33. Thereby, the space between the substrate W and the blocking member 33 is filled with the nitrogen gas, and the oxygen concentration in the atmosphere is reduced. The oxygen concentration in the space between the substrate W and the blocking member 33 is changed according to the degree of opening of the upper gas valve 57 and the upper gas flow control valve 58. The upper gas valve 57 and the upper gas flow control valve 58 are included in the atmospheric oxygen concentration changing unit.

FIG. 4 is a schematic diagram showing a chemical solution creating unit 61 for creating a chemical solution supplied to the substrate W, and a dissolved oxygen concentration changing unit 67 for adjusting the dissolved oxygen concentration of the chemical solution.

The chemical liquid preparation unit 61 includes a tank 62 for storing an alkaline etching liquid corresponding to the second chemical liquid, and a circulation pipe 63 for forming an annular circulation path for circulating the etching liquid in the tank 62. The chemical solution preparation unit 61 further includes a pump 64 for sending the etching solution in the tank 62 to the circulation pipe 63, and a filter 66 for removing foreign substances such as particles from the etching solution flowing in the circulation path. In addition to the above, the chemical solution preparation unit 61 may include a temperature controller 65 that changes the temperature of the etching solution in the tank 62 by heating or cooling the etching solution.

上流 The upstream end and the downstream end of the circulation pipe 63 are connected to the tank 62. The upstream end of the second chemical pipe 52 is connected to the circulation pipe 63, and the downstream end of the second chemical pipe 52 is connected to the center nozzle 45. The pump 64, the temperature controller 65, and the filter 66 are interposed in the circulation pipe 63. The temperature controller 65 may be a heater that heats the liquid at a temperature higher than room temperature (for example, 20 to 30 ° C.), a cooler that cools the liquid at a temperature lower than room temperature, And cooling functions.

The pump 64 always sends the etching solution in the tank 62 into the circulation pipe 63. The etchant is sent from the tank 62 to the upstream end of the circulation pipe 63, and returns to the tank 62 from the downstream end of the circulation pipe 63. Thereby, the etching solution in the tank 62 circulates in the circulation path. While the etching solution is circulating in the circulation path, the temperature of the etching solution is adjusted by the temperature controller 65. Thereby, the etching solution in the tank 62 is maintained at a constant temperature. When the second chemical liquid valve 53 is opened, a part of the etching liquid flowing in the circulation pipe 63 is supplied to the central nozzle 45 via the second chemical liquid pipe 52. The temperature of the etchant supplied to the central nozzle 45 may be room temperature or may be different from room temperature.

The substrate processing apparatus 1 includes a dissolved oxygen concentration changing unit 67 for adjusting the dissolved oxygen concentration of the etching solution. The dissolved oxygen concentration changing unit 67 includes a gas supply pipe 68 for supplying gas into the tank 62 to dissolve the gas into the etching solution in the tank 62. The dissolved oxygen concentration changing unit 67 further includes: an inert gas pipe 69 for supplying an inert gas to a gas supply pipe 68; an open state in which the inert gas flows from the inert gas pipe 69 to the gas supply pipe 68; An inert gas valve 70 that opens and closes between a closed state where the gas is blocked by an inert gas pipe 69, and an inert gas flow adjustment that changes the flow rate of the inert gas supplied from the inert gas pipe 69 to the gas supply pipe 68. And a valve 71.

The gas supply pipe 68 is a bubbling pipe including a gas discharge port 68p arranged in the etching solution in the tank 62. When the inert gas valve 70 is opened, that is, when the inert gas valve 70 is switched from the closed state to the open state, the inert gas such as the nitrogen gas flows at a flow rate corresponding to the opening of the inert gas flow rate adjustment valve 71. The gas is discharged from the gas discharge port 68p. Thereby, many bubbles are formed in the etching solution in the tank 62, and the inert gas dissolves in the etching solution in the tank 62. At this time, dissolved oxygen is discharged from the etching solution, and the concentration of dissolved oxygen in the etching solution decreases. The dissolved oxygen concentration of the etching solution in the tank 62 is changed by changing the flow rate of the nitrogen gas discharged from the gas discharge port 68p.

The dissolved oxygen concentration changing unit 67 includes, in addition to the inert gas pipe 69 and the like, an oxygen-containing gas pipe 72 for supplying an oxygen-containing gas such as clean air to the gas supply pipe 68, and a gas from the oxygen-containing gas pipe 72. An oxygen-containing gas valve 73 that opens and closes between an open state in which the oxygen-containing gas flows through the supply pipe 68 and a closed state in which the oxygen-containing gas is blocked by the oxygen-containing gas pipe 72, and supplies the gas from the oxygen-containing gas pipe 72 to the gas supply pipe 68. And an oxygen-containing gas flow control valve 74 for changing the flow rate of the oxygen-containing gas to be supplied.

When the oxygen-containing gas valve 73 is opened, air, which is an example of the oxygen-containing gas, is discharged from the gas discharge port 68p at a flow rate corresponding to the degree of opening of the oxygen-containing gas flow control valve 74. As a result, many bubbles are formed in the etching solution in the tank 62, and the air dissolves in the etching solution in the tank 62. Air contains oxygen at a rate of about 21 vol%, whereas nitrogen gas contains no or only trace amounts of oxygen. Therefore, the dissolved oxygen concentration of the etching solution in the tank 62 can be increased in a shorter time than when no air is supplied into the tank 62. For example, when the dissolved oxygen concentration of the etching solution becomes too low below the set value, air may be intentionally dissolved in the etching solution in the tank 62.

The dissolved oxygen concentration changing unit 67 may further include an oxygen concentration meter 75 for measuring the dissolved oxygen concentration of the etching solution. FIG. 4 shows an example in which an oxygen concentration meter 75 is interposed in a measurement pipe 76. The oxygen concentration meter 75 may be interposed in the circulation pipe 63. The upstream end of the measurement pipe 76 is connected to the filter 66, and the downstream end of the measurement pipe 76 is connected to the tank 62. The upstream end of the measurement pipe 76 may be connected to the circulation pipe 63. Part of the etching solution in the circulation pipe 63 flows into the measurement pipe 76 and returns to the tank 62. The oxygen concentration meter 75 measures the dissolved oxygen concentration of the etching solution flowing into the measurement pipe 76. The opening degree of at least one of the inert gas valve 70, the inert gas flow control valve 71, the oxygen-containing gas valve 73, and the oxygen-containing gas flow control valve 74 is changed according to the measurement value of the oxygen concentration meter 75.

The chemical preparation unit 61 includes a hydroxide pipe 78 for guiding the quaternary ammonium hydroxide supplied to the tank 62, a hydroxide valve 79 for opening and closing the hydroxide pipe 78, and a hydroxide pipe 78. And a hydroxide flow control valve 80 for changing the flow rate of the quaternary ammonium hydroxide supplied to the tank 62. The chemical preparation unit 61 further includes an inhibitor pipe 81 for guiding the inhibitor supplied to the tank 62, an inhibitor valve 82 for opening and closing the inhibitor pipe 81, and an inhibitor supplied to the tank 62 from the inhibitor pipe 81. An inhibitory substance flow control valve 83 for changing the flow rate of the substance.

When the hydroxide valve 79 is opened, the quaternary ammonium hydroxide is supplied to the tank 62 at a flow rate corresponding to the hydroxide flow rate adjustment valve 80. Similarly, when the inhibitory substance valve 82 is opened, the inhibitory substance is supplied to the tank 62 at a flow rate corresponding to the inhibitory substance flow rate adjustment valve 83. The quaternary ammonium hydroxide supplied from the hydroxide pipe 78 to the tank 62 may be a quaternary ammonium hydroxide liquid or an aqueous solution of a quaternary ammonium hydroxide. Good. Similarly, the inhibitor supplied from the inhibitor pipe 81 to the tank 62 may be a liquid of the inhibitor or an aqueous solution of the inhibitor. The chemical liquid preparation unit 61 may further include a stirrer for stirring the liquid in the tank 62.

(4) When at least one of the quaternary ammonium hydroxide and the inhibitor is supplied to the tank 62, the concentration of the inhibitor contained in the etching solution in the tank 62 changes. The control unit 3 controls the inhibitor concentration changing unit including the hydroxide valve 79, the hydroxide flow control valve 80, the inhibitor valve 82, and the inhibitor flow control valve 83. The hydroxide valve 79 and the inhibitor valve 82 are closed except when preparing an etchant or when changing the concentration of the inhibitor. In other words, when preparing the etchant or changing the concentration of the inhibitor, at least one of the hydroxide valve 79 and the inhibitor valve 82 is opened, and the concentration of the inhibitor in the etchant becomes an appropriate value. Be changed.

FIG. 5 is a block diagram showing hardware of the control device 3. As shown in FIG.

The control device 3 is a computer including a computer main body 3a and a peripheral device 3d connected to the computer main body 3a. The computer main body 3a includes a CPU 3b (central processing unit) for executing various instructions, and a main storage device 3c for storing information. The peripheral device 3d includes an auxiliary storage device 3e that stores information such as the program P, a reading device 3f that reads information from the removable medium RM, and a communication device 3g that communicates with another device such as a host computer.

The control device 3 is connected to the input device and the display device. The input device is operated when an operator such as a user or a maintenance person inputs information to the substrate processing apparatus 1. The information is displayed on the screen of the display device. The input device may be any of a keyboard, a pointing device, and a touch panel, or may be other devices. A touch panel display serving also as an input device and a display device may be provided in the substrate processing apparatus 1.

(4) The CPU 3b executes the program P stored in the auxiliary storage device 3e. The program P in the auxiliary storage device 3e may be installed in the control device 3 in advance, or may be transmitted from the removable medium RM to the auxiliary storage device 3e through the reading device 3f, It may be transmitted from an external device such as a host computer to the auxiliary storage device 3e through the communication device 3g.

(4) The auxiliary storage device 3e and the removable medium RM are non-volatile memories that retain data even when power is not supplied. The auxiliary storage device 3e is, for example, a magnetic storage device such as a hard disk drive. The removable medium RM is, for example, an optical disk such as a compact disk or a semiconductor memory such as a memory card. The removable medium RM is an example of a computer-readable recording medium on which the program P is recorded. The removable medium RM is a non-transitory tangible recording medium (non-transitory \ tangible \ recording \ medium).

The auxiliary storage device 3e stores a plurality of recipes. The recipe is information that defines processing contents, processing conditions, and processing procedures for the substrate W. The plurality of recipes differ from each other in at least one of the processing content, processing conditions, and processing procedure of the substrate W. The control device 3 controls the substrate processing apparatus 1 so that the substrate W is processed according to the recipe specified by the host computer. Each step described below is executed by the control device 3 controlling the substrate processing apparatus 1. In other words, the control device 3 is programmed to execute each step.

FIG. 6 is a schematic view showing an example of a cross section of the substrate W before and after the processing shown in FIG. 7 is performed.

6 shows a cross section of the substrate W before the processing (etching) shown in FIG. 7 is performed, and the right side of FIG. 6 shows a substrate W after the processing (etching) shown in FIG. 7 is performed. 2 shows a cross section of FIG. As shown on the right side of FIG. 6, when the substrate W is etched, a plurality of recesses R1 recessed in the surface direction of the substrate W (the direction orthogonal to the thickness direction Dt of the substrate W) are formed on the side surface 92s of the concave portion 92. You.

As shown in FIG. 6, the substrate W is composed of a laminated film 91 formed on a base material such as a silicon wafer and a thickness direction Dt of the substrate W from the outermost surface Ws of the substrate W (the surface W of the base material of the substrate W (In a direction perpendicular to). The laminated film 91 includes a plurality of polysilicon films P1, P2, P3 and a plurality of silicon oxide films O1, O2, O3. The polysilicon films P1 to P3 are examples of an etching target, and the silicon oxide films O1 to O3 are examples of a non-etching target. Silicon oxide is a substance that does not dissolve or hardly dissolves in an alkaline etching solution containing a quaternary ammonium hydroxide.

(4) The plurality of polysilicon films P1 to P3 and the plurality of silicon oxide films O1 to O3 are stacked in the thickness direction Dt of the substrate W such that the polysilicon film and the silicon oxide film are alternately replaced. The polysilicon films P1 to P3 are thin films on which a deposition step of depositing polysilicon on the substrate W and a heat treatment step of heating the deposited polysilicon have been performed (see FIG. 7). The polysilicon films P1 to P3 may be thin films on which no heat treatment process has been performed.

凹部 As shown in FIG. 6, the concave portion 92 penetrates the plurality of polysilicon films P1 to P3 and the plurality of silicon oxide films O1 to O3 in the thickness direction Dt of the substrate W. Side surfaces of the polysilicon films P1 to P3 and the silicon oxide films O1 to O3 are exposed at side surfaces 92s of the concave portions 92. The concave portion 92 may be any of a trench, a via hole, and a contact hole, or may be other than these.

前 Before the processing (etching) shown in FIG. 7 is started, a natural oxide film is formed on the surface layers of the polysilicon films P1 to P3 and the silicon oxide films O1 to O3. The two-dot chain line on the left side of FIG. 6 indicates the contour of the native oxide film. Hereinafter, the natural oxide films of the polysilicon films P1 to P3 and the silicon oxide films O1 to O3 are removed by supplying DHF, which is an example of an oxide film removing solution, and then the polysilicon films P1 to P3 are removed by supplying an etching solution. The selective etching process will be described.

FIG. 7 is a process diagram for describing an example of the processing of the substrate W performed by the substrate processing apparatus 1.

Hereinafter, an example of the processing of the substrate W performed by the substrate processing apparatus 1 will be described with reference to FIGS. 1A, 2, 3, and 7. In the substrate processing apparatus 1, the steps after the start in FIG. 7 are executed.

(4) When the substrate W is processed by the substrate processing apparatus 1, a loading step of loading the substrate W into the chamber 4 is performed (Step S1 in FIG. 7).

Specifically, the center robot CR supports the substrate W with the hand H1 in a state where the lifting frame 32 and the blocking member 33 are located at the upper position, and all the guards 25 are located at the lower position. , The hand H1 enters the chamber 4. Then, the center robot CR places the substrate W on the hand H1 on the plurality of chuck pins 11 with the surface of the substrate W facing upward. Thereafter, the plurality of chuck pins 11 are pressed against the outer peripheral surface of the substrate W, and the substrate W is gripped. After placing the substrate W on the spin chuck 10, the center robot CR retracts the hand H1 from inside the chamber 4.

Next, the upper gas valve 57 and the lower gas valve 21 are opened, and the upper central opening 38 of the blocking member 33 and the lower central opening 18 of the spin base 12 start discharging nitrogen gas. Thereby, the oxygen concentration in the atmosphere in contact with the substrate W is reduced. Further, the blocking member elevating unit 31 lowers the elevating frame 32 from the upper position to the lower position, and the guard elevating unit 27 raises one of the guards 25 from the lower position to the upper position. At this time, the spin base 12 is held at a reference rotation angle at which the plurality of upper support portions 43 respectively overlap the plurality of lower support portions 44 in plan view. Therefore, the upper support 43 of the blocking member 33 is supported by the lower support 44 of the spin base 12, and the blocking member 33 is separated from the lifting frame 32. Thereafter, the spin motor 14 is driven, and the rotation of the substrate W is started (Step S2 in FIG. 7).

Next, a first chemical liquid supply step of supplying DHF, which is an example of the first chemical liquid, to the upper surface of the substrate W is performed (Step S3 in FIG. 7).

Specifically, the first chemical liquid valve 51 is opened in a state where the blocking member 33 is located at the lower position, and the central nozzle 45 starts discharging DHF. The DHF discharged from the center nozzle 45 collides with the center of the upper surface of the substrate W, and then flows outward along the upper surface of the rotating substrate W. Thus, a DHF liquid film covering the entire upper surface of the substrate W is formed, and DHF is supplied to the entire upper surface of the substrate W. When a predetermined time has elapsed since the first chemical liquid valve 51 was opened, the first chemical liquid valve 51 is closed, and the discharge of DHF is stopped.

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

Specifically, the upper rinsing liquid valve 55 is opened while the blocking member 33 is located at the lower position, and the center nozzle 45 starts discharging pure water. The pure water colliding with the center of the upper surface of the substrate W flows outward along the upper surface of the rotating substrate W. DHF on the substrate W is washed away by pure water discharged from the center nozzle 45. As a result, a liquid film of pure water covering the entire upper surface of the substrate W is formed. When a predetermined time has elapsed since the opening of the upper rinsing liquid valve 55, the upper rinsing liquid valve 55 is closed, and the discharge of pure water is stopped.

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

Specifically, the second chemical liquid valve 53 is opened in a state where the blocking member 33 is located at the lower position, and the center nozzle 45 starts discharging the etching liquid. Before the discharge of the etching liquid is started, the guard elevating unit 27 may move at least one guard 25 vertically in order to switch the guard 25 that receives the liquid discharged from the substrate W. The etchant colliding 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 with an etchant discharged from the central nozzle 45. As a result, a liquid film of the etchant covering the entire upper surface of the substrate W is formed. When a predetermined time has elapsed since the second chemical liquid valve 53 was opened, the second chemical liquid valve 53 is closed, and the discharge of the etching liquid is stopped.

Next, a second rinsing liquid supply step of supplying pure water, which is an example of a rinsing liquid, to the upper surface of the substrate W is performed (Step S6 in FIG. 7).

Specifically, the upper rinsing liquid valve 55 is opened while the blocking member 33 is located at the lower position, and the center nozzle 45 starts discharging pure water. The pure water colliding with the center of the upper surface of the substrate W flows outward along the upper surface of the rotating substrate W. The etchant on the substrate W is washed away by pure water discharged from the center nozzle 45. As a result, a liquid film of pure water covering the entire upper surface of the substrate W is formed. When a predetermined time has elapsed since the opening of the upper rinsing liquid valve 55, the upper rinsing liquid valve 55 is closed, and the discharge of pure water is stopped.

Next, a drying step of drying the substrate W by rotating the substrate W is performed (Step S7 in FIG. 7).

Specifically, the spin motor 14 accelerates the substrate W in the rotation direction in a state in which the blocking member 33 is located at the lower position, and the substrate W during the period from the first chemical liquid supply step to the second rinse liquid supply step is removed. The substrate W is rotated at a high rotation speed (for example, several thousand rpm) higher than the rotation speed. Thereby, the liquid is removed from the substrate W, and the substrate W is dried. When a predetermined time has elapsed since the start of the high-speed rotation of the substrate W, the spin motor 14 stops rotating. At this time, the spin motor 14 stops the spin base 12 at the reference rotation angle. Thus, the rotation of the substrate W is stopped (Step S8 in FIG. 7).

Next, an unloading step of unloading the substrate W from the chamber 4 is performed (Step S9 in FIG. 7).

Specifically, the blocking member elevating unit 31 raises the elevating frame 32 to the upper position, and the guard elevating unit 27 lowers all the guards 25 to the lower position. Further, the upper gas valve 57 and the lower gas valve 21 are closed, and the upper central opening 38 of the blocking member 33 and the lower central opening 18 of the spin base 12 stop discharging nitrogen gas. After that, the center robot CR causes the hand H1 to enter the chamber 4. The center robot CR supports the substrate W on the spin chuck 10 with the hand H1 after the plurality of chuck pins 11 release the grip of the substrate W. Thereafter, the center robot CR retracts the hand H1 from the inside of the chamber 4 while supporting the substrate W with the hand H1. Thus, the processed substrate W is carried out of the chamber 4.

FIGS. 8A and 8B are diagrams for explaining a mechanism assumed when contact between hydroxide ions and polysilicon is inhibited by an inhibitor. 8A and 8B show an example where the inhibitor is propylene glycol.

When the quaternary ammonium hydroxide is dissolved in water, the quaternary ammonium hydroxide separates into a cation (cation) and a hydroxide ion (OH ⁻ ). Silicon contained in polysilicon reacts with hydroxide ions as represented by the formula “Si + 4OH ⁻ → Si (OH) ₄ + 4e ⁻ ”. Thereby, the silicon contained in the polysilicon is dissolved in the etching solution, and the etching of the polysilicon to be etched proceeds.

When an inhibitor is included in the etching solution, the inhibitor acts as a three-dimensional barrier for hydroxide ions, and the hydroxide ions are suspended by the etching solution or absorbed or coordinated with polysilicon by the inhibitor, Blocked from moving towards polysilicon. Therefore, the number of hydroxide ions reaching the polysilicon decreases, and the etching rate of the polysilicon decreases. By such a mechanism, it is considered that the contact between the hydroxide ion and the polysilicon is inhibited by the inhibitor.

Although the decrease in the etching rate occurs on a plurality of crystal planes of the silicon single crystal contained in the polysilicon, the etching rate is relatively largely reduced on the crystal plane having a high etching rate among the plurality of crystal planes of the silicon single crystal. . As a result, the difference between the etching rates in the plurality of crystal planes decreases, and the anisotropy of the silicon single crystal with respect to the etching solution decreases. That is, the polysilicon is uniformly etched regardless of the plane orientation of the silicon single crystal exposed on the surface of the polysilicon. By such a mechanism, it is considered that the polysilicon is etched with a uniform etching amount at any place.

FIG. 9 is a graph showing an example of the relationship between the etching rates of three crystal planes of a silicon single crystal and the concentration of propylene glycol in the etching solution.

FIG. 9 shows the (110) plane, the (100) plane, and the (100) plane when a silicon single crystal is etched using three types of TMAHs (zero concentration, first concentration, and second concentration) having different concentrations of propylene glycol. The measured value of the etching rate of the (111) plane is shown. The etching conditions when the measured values shown in FIG. 9 were obtained were the same except for the concentration of propylene glycol in TMAH. For example, the temperature of TMAH is 40 ° C., and the concentration of TMAH to which propylene glycol is not added is 5 wt% (mass percent concentration). The dissolved oxygen concentration of TMAH is previously reduced.

示す As shown in FIG. 9, when the concentration of propylene glycol is zero, the etching rate on the (110) plane is the highest and the etching rate on the (111) plane is the lowest. As can be seen from the three curves in FIG. 9, the addition of propylene glycol to TMAH decreases the etch rate. Further, the etching rate of each crystal plane decreases as the concentration of propylene glycol increases.

However, when the concentration of propylene glycol is in the range from zero to the first concentration, the etching rate of the (110) plane and the (100) plane is sharply reduced, while the etching rate of the (111) plane is very slow. Has decreased. Therefore, in this range, as the concentration of propylene glycol increases, the difference between the maximum value of the etching rate and the minimum value of the etching rate decreases.

When the propylene glycol concentration exceeds the first concentration, the rate of decrease in the etching rate (the ratio of the absolute value of the change in the etching rate to the absolute value of the change in the concentration of the propylene glycol) decreases, but the first concentration Up to a value near the middle between the second concentration and the second concentration, the rate of decrease in the etching rate on the (110) plane and the (100) plane is larger than the rate of decrease in the etching rate on the (111) plane. Therefore, even when the concentration of propylene glycol is in a range up to a value near the middle between the first concentration and the second concentration, the difference between the maximum value of the etching rate and the minimum value of the etching rate decreases as the concentration of propylene glycol increases. are doing.

As described above, when propylene glycol is added to TMAH exhibiting anisotropy with respect to a silicon single crystal, plane orientation selectivity, that is, the difference between the maximum value of the etching rate and the minimum value of the etching rate decreases, and the The anisotropy of the silicon single crystal decreases. On the other hand, when the concentration of propylene glycol is in a range up to a value near the middle between the first concentration and the second concentration, as the concentration of propylene glycol increases, the etching rates of the (110) plane and the (100) plane increase. Decreases at a decreasing rate. Therefore, the concentration of propylene glycol may be set according to the required etching uniformity and etching rate.

For example, an inhibitor such as propylene glycol may be excessively administered to the etching solution. According to the measurement results shown in FIG. 9, when a small amount of propylene glycol (for example, about 5 to 10 wt%) is added, the effect of relaxing anisotropy is relatively small, but a large amount of propylene glycol (for example, 20 wt% or more) is added. When added, that is, when propylene glycol is excessively administered, a remarkable effect of alleviating anisotropy is observed.

Although excessive administration of propylene glycol can significantly reduce the anisotropy, it also has the disadvantage of lowering the etching rate. And the balance between throughput requirements. For example, control device 3 may determine the concentration of the inhibitor in the etchant based on a target value of a difference between etching rates on a plurality of crystal planes of silicon single crystal constituting polysilicon. The target value of the difference between the etching rates may be specified in a recipe, or may be input to the control device 3 from an external device such as a host computer.

As described above, in the present embodiment, the alkaline etching solution containing the quaternary ammonium hydroxide, water, and the inhibitor is mixed with the etching objects P1 to P3 (see FIG. 6) and the etching objects P1 to P3. Different non-etching targets O1 to O3 (see FIG. 6) are supplied to the exposed substrate W. When the quaternary ammonium hydroxide is dissolved in water, the quaternary ammonium hydroxide separates into cations (cations) and hydroxide ions. The silicon single crystal contained in the etching objects P1 to P3 reacts with hydroxide ions and is dissolved in the etching solution. The etching rates of the etching objects P1 to P3 are higher than the etching rates of the non-etching objects O1 to O3. Thereby, the etching objects P1 to P3 are selectively etched.

The inhibitor inhibits contact between the hydroxide ions and the etching objects P1 to P3. That is, the inhibitor acts as a three-dimensional barrier for hydroxide ions, and reduces the number of hydroxide ions that react with the etching objects P1 to P3. Thereby, the etching rate of the etching objects P1 to P3 decreases. Further, the etching rate does not decrease uniformly on a plurality of crystal planes of the silicon single crystal, but relatively decreases on a crystal plane having a high etching rate among them. As a result, the difference between the etching rates in the plurality of crystal planes decreases, and the anisotropy of the silicon single crystal with respect to the etching solution decreases. That is, the etching of the silicon single crystal contained in the etching objects P1 to P3 approaches the isotropic etching, and the etching objects P1 to P3 are etched with a uniform etching amount in any place.

(4) As described above, hydroxide ions in the etching solution are prevented from moving toward the polysilicon by an inhibitor suspended in the etching solution or adsorbed or coordinated with the polysilicon. If the number of inhibitory molecules present in the etching solution is the same, the larger the inhibitory molecule, the more difficult it is for hydroxide ions to reach the etching objects P1 to P3. If an inhibitor whose one molecule is larger than a hydroxide ion is used as in this embodiment, the number of hydroxide ions in contact with the etching objects P1 to P3 can be effectively reduced.

In the present embodiment, the quaternary ammonium hydroxide, water, and the inhibitor are mixed not before being discharged from the discharge port 47 but before being discharged from the discharge port 47. As a result, an etching solution is prepared in which the quaternary ammonium hydroxide, water, and the inhibitor are uniformly mixed. After that, the etchant is discharged from the discharge port 47 toward the substrate W and supplied to the substrate W. Therefore, the substrate W can be treated more uniformly than when the quaternary ammonium hydroxide, water, and the inhibitor are mixed after being discharged from the discharge port 47.

In this embodiment, DHF, which is an example of the oxide film removing liquid, is supplied to the substrate W, and the natural oxide films of the etching objects P1 to P3 are removed from the surface layers of the etching objects P1 to P3. Thereafter, an etching solution is supplied to the substrate W, and the etching objects P1 to P3 are selectively etched. The natural oxide films of the etching objects P1 to P3 are mainly composed of silicon oxide. The etching liquid is a liquid that etches the etching objects P1 to P3 without etching or almost not etching the silicon oxide. This is because hydroxide ions react with silicon, but do not or rarely react with silicon oxide. Therefore, the etching objects P1 to P3 can be efficiently etched by removing the natural oxide films of the etching objects P1 to P3 in advance.

In this embodiment, the etching targets P1 to P3 subjected to the heat treatment step of heating the deposited polysilicon are etched with an alkaline etching solution. Heating the deposited polysilicon under appropriate conditions increases the polysilicon grain size. Therefore, as compared with the case where the heat treatment step is not performed, the silicon single crystal contained in the etching objects P1 to P3 is larger. This means that the number of silicon single crystals exposed on the surfaces of the etching objects P1 to P3 decreases, and the influence of anisotropy increases. Therefore, by supplying an etching solution containing a quaternary ammonium hydroxide, water and an inhibitor to the etching objects P1 to P3, the influence of anisotropy can be effectively reduced.

In this embodiment, the concentration of dissolved oxygen in at least one of the quaternary ammonium hydroxide, water, and the inhibitor is reduced. Accordingly, the concentration of dissolved oxygen in the etching solution prepared from these decreases. When an etching solution having a high dissolved oxygen concentration is supplied to the substrate W, a part of the surface layer of the etching objects P1 to P3 is oxidized and changes to silicon oxide. This means that the etching rates of the etching objects P1 to P3 are further reduced. Accordingly, by supplying an etching solution having a low dissolved oxygen concentration to the substrate W, it is possible to reduce the anisotropy of the silicon single crystal while suppressing a decrease in the etching rate of the etching objects P1 to P3.

In the present embodiment, the etching solution is supplied to the substrate W in a state where the oxygen concentration in the atmosphere is low. This reduces the amount of oxygen dissolved from the atmosphere into the etching solution, thereby suppressing an increase in the concentration of dissolved oxygen. When an etching solution having a high dissolved oxygen concentration is supplied to the substrate W, the etching rate of the etching objects P1 to P3 further decreases. Therefore, a further decrease in the etching rate can be suppressed by reducing the oxygen concentration in the atmosphere.

Next, a second embodiment will be described.

The main difference between the first embodiment and the second embodiment is that the substrate processing apparatus 101 is a batch-type apparatus that processes a plurality of substrates W at a time.

FIG. 10 is a schematic view showing a chemical processing unit 102 provided in a substrate processing apparatus 101 according to the second embodiment of the present invention. 10 and 11, the same components as those shown in FIGS. 1 to 9 are denoted by the same reference numerals as those in FIG. 1 and the like, and description thereof is omitted.

The substrate processing apparatus 101 includes a plurality of processing units that simultaneously supply a processing liquid to a plurality of substrates W, a loading operation for simultaneously loading the plurality of substrates W into the processing unit, and a unloading operation of the plurality of substrates W from the processing units. And a control unit 3 for controlling the substrate processing apparatus 101.

The plurality of processing units include the chemical processing unit 102 that supplies an alkaline etchant corresponding to the second chemical to the plurality of substrates W simultaneously. The chemical processing unit 102 includes an immersion tank 103 for storing an etching liquid and simultaneously carrying a plurality of substrates W, and an overflow tank 104 for receiving the etching liquid overflowing from the immersion tank 103. Although not shown, the plurality of processing units are a rinsing liquid processing unit for simultaneously supplying a rinsing liquid to the plurality of substrates W supplied with the etching liquid, and simultaneously drying the plurality of substrates W supplied with the rinsing liquid. A drying processing unit.

The chemical treatment unit 102 includes, in addition to the immersion tank 103 and the overflow tank 104, a housing 105 that houses the immersion tank 103 and the overflow tank 104, a shutter 106 that opens and closes a loading / unloading port 105 a provided at an upper part of the housing 105, An opening / closing unit 107 for moving the shutter 106 between a closed position where the carry-in / out port 105a is closed by the shutter 106 and an open position where the carry-in / out port 105a is opened is included. The plurality of substrates W pass vertically through the loading / unloading port 105a. The transport unit moves the plurality of substrates W between the lower position where the plurality of substrates W are immersed in the etching liquid in the immersion tank 103 and the upper position where the plurality of substrates W is positioned above the etching liquid in the immersion tank 103. Lifter 108 which moves up and down while holding the substrate W at the same time.

The chemical processing unit 102 includes two chemical nozzles 109 provided with a second chemical liquid outlet 47 for discharging an alkaline etching liquid corresponding to the second chemical, a drain pipe 116 for discharging the liquid in the immersion tank 103, including. When the chemical solution nozzle 109 discharges the etchant, the etchant is supplied into the immersion tank 103 and an upward flow is formed in the etchant in the immersion tank 103. Further, when the drain valve 117 interposed in the drain pipe 116 is opened, the liquid in the immersion tank 103 such as the etching solution is discharged to the drain pipe 116. The upstream end of the drainage pipe 116 is connected to the bottom of the immersion tank 103.

The circulation pipe 63 for circulating the etching liquid in the tank 62 of the chemical liquid preparation unit 61 is connected to two chemical liquid nozzles 109 via a chemical liquid pipe 110. The chemical pipe 110 guides the etchant supplied from the circulation pipe 63 toward the two chemical nozzles 109, and guides the etchant supplied from the common pipe 110c to the two chemical nozzles 109, respectively. And two branch pipes 110b. The upstream end of the branch pipe 110b is connected to the common pipe 110c, and the downstream end of the branch pipe 110b is connected to the chemical nozzle 109.

(4) When the empty immersion tank 103 is filled with the etching liquid, the chemical liquid valve 114 interposed in the common pipe 110c is opened. Thus, the etching liquid in the common pipe 110c is supplied to the two chemical liquid nozzles 109 via the two branch pipes 110b, and is discharged from the two chemical liquid nozzles 109. When the inside of the immersion tank 103 is filled with the etching liquid, the chemical liquid valve 114 is closed, and the supply of the etching liquid from the tank 62 to the immersion tank 103 is stopped. The chemical liquid valve 114 is closed except when the empty immersion tank 103 is filled with the etching liquid.

The overflow tank 104 is connected to a common pipe 110c via a return pipe 115. The upstream end of the return pipe 115 is connected to the overflow tank 104, and the downstream end of the return pipe 115 is connected to the common pipe 110 c at a position downstream of the chemical liquid valve 114. The etching liquid overflowing from the immersion tank 103 to the overflow tank 104 is sent again to the two chemical liquid nozzles 109 by the pump 113 and is filtered by the filter 111 before reaching the two chemical liquid nozzles 109. Chemical treatment unit 102 may include a temperature controller 112 that changes the temperature of the etching solution in immersion tank 103 by heating or cooling the etching solution.

The dissolved oxygen concentration changing unit 67 that adjusts the dissolved oxygen concentration of the etching solution includes at least one unit that dissolves a low oxygen gas having an oxygen concentration lower than the oxygen concentration in air (about 21 vol%) in the etching solution in the immersion tank 103. It further includes three gas nozzles 118. FIG. 10 shows an example in which two gas nozzles 118 are provided and the low oxygen gas is a nitrogen gas. The two gas nozzles 118 are attached to the immersion tank 103, and discharge nitrogen gas inside the immersion tank 103.

The dissolved oxygen concentration changing unit 67 includes a gas supply pipe 119 for supplying nitrogen gas to at least one gas nozzle 118, an open state in which nitrogen gas flows from the gas supply pipe 119 to at least one gas nozzle 118, and a gas supply pipe 119. A gas valve 120 that opens and closes between a closed state and a gas flow adjustment valve 121 that changes the flow rate of nitrogen gas supplied from the gas supply pipe 119 to at least one gas nozzle 118.

When the gas valve 120 is opened while the etchant is in the immersion tank 103, nitrogen gas is discharged from the two gas nozzles 118 at a flow rate corresponding to the degree of opening of the gas flow rate adjustment valve 121. As a result, many bubbles are formed in the etching solution in the immersion tank 103, and the nitrogen gas dissolves in the etching solution in the immersion tank 103. At this time, dissolved oxygen is discharged from the etching solution, and the concentration of dissolved oxygen in the etching solution decreases. This suppresses an increase in the concentration of dissolved oxygen in the etching solution in the immersion tank 103.

The dissolved oxygen concentration changing unit 67 further includes a purge gas supply pipe 122 for supplying a low oxygen gas such as a nitrogen gas into the housing 105, an open state in which the nitrogen gas flows from the purge gas supply pipe 122 to the housing 105, and a purge gas supply for the nitrogen gas. And a purge gas valve 123 that opens and closes between a closed state blocked by the supply pipe 122. The dissolved oxygen concentration changing unit 67 further includes a gas discharge pipe 124 for guiding the gas in the housing 105 to the outside of the housing 105, and a gas discharge pipe 124 when the pressure in the housing 105 exceeds the upper limit pressure. And a relief valve 125 for discharging gas.

(4) If the shutter 106 is closed while the purge gas valve 123 is open, the amount of gas discharged through the carry-in / out port 105a decreases, so that the air pressure in the housing 105 increases. When the pressure in the housing 105 exceeds the upper limit pressure, the relief valve 125 is opened, and the gas in the housing 105 is discharged to the gas discharge pipe 124. Thereby, air is discharged from the housing 105, and the inside of the housing 105 is filled with nitrogen gas. Therefore, the amount of oxygen dissolved in the etching solution in the immersion tank 103 from the atmosphere in the housing 105 is reduced, and an increase in the dissolved oxygen concentration is suppressed.

FIG. 11 is a process diagram showing an example of a flow from creation of a new etching solution to discharge of the used etching solution from the immersion tank 103.

{Operations to be described later are executed by the control device 3 controlling the substrate processing apparatus 101. In other words, the control device 3 is programmed to cause the substrate processing apparatus 101 to execute the following operation. Hereinafter, FIG. 10 and FIG. 11 will be referred to.

(4) The etching liquid supplied to the immersion tank 103 of the chemical processing unit 102 is created by the chemical creating unit 61 (step S11 in FIG. 11). Specifically, TMAH is supplied from the hydroxide pipe 78 into the tank 62, and propylene glycol is supplied from the inhibitory substance pipe 81 into the tank 62. Thereby, TMAH and propylene glycol are mixed in the tank 62, and an etchant is created. Further, an inert gas such as a nitrogen gas is supplied from the gas supply pipe 68 into the tank 62. Thereby, the dissolved oxygen concentration of the etching solution in the tank 62 decreases (Step S12 in FIG. 11).

When the preparation of the etching solution is completed, the purge gas valve 123 is opened, and the supply of the nitrogen gas from the purge gas supply pipe 122 to the housing 105 is started (Step S13 in FIG. 11). Thus, the inside of the housing 105 is filled with the inert gas. Thereafter, the chemical liquid valve 114 is opened, and the supply of the etching liquid from the tank 62 to the immersion tank 103 is started (Step S14 in FIG. 11). When the inside of the immersion tank 103 is filled with the etching liquid, the chemical liquid valve 114 is closed, and the supply of the etching liquid from the tank 62 to the immersion tank 103 is stopped. Thereafter, the gas valve 120 is opened, and the dissolution of the nitrogen gas into the etching solution in the immersion tank 103 is started (Step S15 in FIG. 11). This suppresses an increase in the concentration of dissolved oxygen in the etching solution in the immersion tank 103.

(4) After the discharge of the nitrogen gas from the gas nozzle 118 is started, the lifter 108 descends from the upper position to the lower position while holding the plurality of substrates W. Thereafter, the opening / closing unit 107 moves the shutter 106 from the open position to the closed position. Thereby, all the substrates W included in one batch are submerged in the etching solution in the immersion tank 103 (Step S16 in FIG. 11). Therefore, the etchant is simultaneously supplied to the plurality of substrates W, and the etching target such as the polysilicon films P1 to P3 (see FIG. 6) is etched. When a predetermined time elapses after the lifter 108 moves to the lower position, the opening / closing unit 107 moves the shutter 106 to the open position, and the lifter 108 moves up to the upper position.

にして Thus, all the substrates W included in one batch are immersed in the etching solution in the immersion tank 103, and then are unloaded from the immersion tank 103. This series of flows is repeated for each batch. That is, when all the substrates W included in one batch are unloaded from the immersion tank 103, all the substrates W included in another batch are immersed in the etching solution in the immersion tank 103, as described above. Is done. Then, when the number of uses or the use time of the etching solution in the immersion tank 103 reaches the upper limit, the etching solution in the immersion tank 103 is replaced with a new etching solution.

Specifically, the gas valve 120 is closed, and the dissolution of the nitrogen gas in the etching solution in the immersion tank 103 is stopped (Step S17 in FIG. 11). Further, the purge gas valve 123 is closed, and the supply of the nitrogen gas from the purge gas supply pipe 122 to the housing 105 is stopped (Step S18 in FIG. 11). Thereafter, the drain valve 117 is opened, and the etching solution in the immersion tank 103 is discharged to the drain pipe 116 (Step S19 in FIG. 11). When the inside of the immersion tank 103 becomes empty, a new etching solution prepared in advance is supplied to the immersion tank 103 (Steps S11 to S14 in FIG. 11).

Other Embodiments The present invention is not limited to the contents of the above-described embodiments, and various modifications are possible.

{For example, TMAH and propylene glycol may be mixed in the space between the discharge port 47 of the central nozzle 45 and the substrate W, or may be mixed on the substrate W. Alternatively, TMAH and propylene glycol may be mixed not between inside the tank 62 but between the tank 62 and the discharge port 47 of the center nozzle 45. Specifically, the inhibitory substance pipe 81 for guiding propylene glycol may be connected to the flow path of the chemical solution from the tank 62 to the discharge port 47 of the center nozzle 45 instead of the tank 62.

FIG. 12 shows an example in which the inhibitory substance pipe 81 is connected to the second chemical liquid pipe 52. In the example shown in FIG. 12, TMAH is stored in the tank 62, and an aqueous solution of propylene glycol is stored in the tank 131. The inhibitor pipe 81 may be connected to the center nozzle 45. Instead of the aqueous solution of propylene glycol, a liquid of propylene glycol may be stored in the tank 131.

Regardless of whether the inhibitory substance pipe 81 is connected to either the second chemical liquid pipe 52 or the center nozzle 45, the propylene glycol in the tank 131 is sent from the tank 131 to the inhibitory substance pipe 81 by the pump 132, and the second chemical liquid pipe It is mixed with TMAH in 52 or in the central nozzle 45. As a result, an alkaline etching solution containing TMAH, propylene glycol, and water is discharged from the discharge port 47 of the central nozzle 45.

(4) The alkaline etching solution containing TMAH and propylene glycol may be supplied not to the upper surface of the substrate W but to the lower surface of the substrate W. Alternatively, the etching liquid may be supplied to both the upper surface and the lower surface of the substrate W. In these cases, the etchant may be discharged to the lower surface nozzle 15.

The dissolved oxygen concentration changing unit 67 may be omitted from the substrate processing apparatus. That is, an etchant that does not reduce the concentration of dissolved oxygen may be supplied to the substrate W.

筒 The tubular portion 37 may be omitted from the blocking member 33. The upper support 43 and the lower support 44 may be omitted from the blocking member 33 and the spin chuck 10.

The blocking member 33 may be omitted from the processing unit 2. In this case, a nozzle for discharging a processing liquid such as a first chemical liquid toward the substrate W may be provided in the processing unit 2. The nozzle may be a scan nozzle movable horizontally in the chamber 4 or a fixed nozzle fixed to the partition 6 of the chamber 4. The nozzle may have a plurality of liquid discharge ports for supplying the processing liquid to the upper surface or the lower surface of the substrate W by simultaneously discharging the processing liquid toward a plurality of positions separated in the radial direction of the substrate W. In this case, at least one of the flow rate, temperature, and concentration of the processing liquid to be discharged may be changed for each liquid discharge port.

枚数 The number of polysilicon films included in the laminated film 91 may be one. Similarly, the number of silicon oxide films included in the stacked film 91 may be one.

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

The non-etching target may be a substance other than silicon oxide.

The substrate processing apparatus is not limited to an apparatus for processing a disk-shaped substrate W, but may be an apparatus for processing a polygonal substrate W.

２Two or more of all the above-described configurations may be combined. Two or more of all the steps described above may be combined.

In addition, various design changes can be made within the scope of the matters described in the claims.

(4) The chemical solution creating unit 61 is an example of an etchant creating means and an etchant manufacturer. The center nozzle 45 is an example of a selective etching unit and a selective etching nozzle. The second chemical liquid discharge port 47 is an example of a discharge port. The second chemical liquid pipe 52, the tank 62, the hydroxide pipe 78, and the inhibitory substance pipe 81 are an example of a mixing unit and a mixer. The central nozzle 45, particularly the first chemical liquid discharge port 46, is an example of a natural oxide film removing means and a natural oxide film remover. The dissolved oxygen concentration changing unit 67 is an example of a dissolved oxygen concentration changing unit and a dissolved oxygen concentration changer. The lower gas valve 21, the lower gas flow control valve 22, the upper gas valve 57, and the upper gas flow control valve 58 are an example of an atmosphere oxygen concentration changing unit and an atmosphere oxygen concentration changer.

Although the embodiments of the present invention have been described in detail, these are only specific examples used for clarifying the technical contents of the present invention, and the present invention is interpreted by limiting to these specific examples. Instead, the spirit and scope of the invention is limited only by the appended claims.

1: Substrate processing apparatus 15: Lower surface nozzle 18: Lower central opening 21: Lower gas valve 22: Lower gas flow control valve 45: Central nozzle 46: First chemical liquid discharge port 47: Second chemical liquid discharge port 49: Upper gas discharge port 52 : Second chemical liquid pipe 57: Upper gas valve 58: Upper gas flow rate adjusting valve 61: Chemical liquid preparation unit 62: Tank 67: Dissolved oxygen concentration changing unit 78: Hydroxide pipe 81: Inhibiting substance pipe 91: Laminated film 92: Depression 101 : Substrate processing apparatus 109: chemical solution nozzle 118: gas nozzles O1 to O3: silicon oxide films P1 to P3: polysilicon film W: substrate

Claims

An etching object including polysilicon, a non-etching object different from the etching object, and a substrate processing method for supplying an alkaline etching solution to an exposed substrate,
The alkaline etching solution containing quaternary ammonium hydroxide, water, and an inhibitor that inhibits contact between the hydroxide ion generated from the quaternary ammonium hydroxide and the object to be etched; An etching solution making process to be made;
By supplying the etchant created in the etchant creating step to the substrate where the etching target and the non-etching target are exposed, the etching target is suppressed while suppressing the etching of the non-etching target. A selective etching step of etching a substrate.
The etching solution forming step includes a concentration determining step of determining the concentration of the inhibitor in the etching solution based on a target value of a difference between etching rates on a plurality of crystal planes of the silicon single crystal constituting the polysilicon. The substrate processing method according to claim 1.
3. The substrate processing method according to claim 1, wherein the concentration of the inhibitor in the etching solution created in the etching solution creating step is equal to or greater than 20 percent by mass and less than 100 percent by mass.
(4) The substrate processing method according to any one of (1) to (3), wherein the molecule of the inhibitor is larger than the hydroxide ion.
The etching solution forming step includes, before the etching solution is discharged from a discharge port, a pre-discharge mixing step of mixing the quaternary ammonium hydroxide, the water, and the inhibitor,
The substrate processing according to any one of claims 1 to 4, wherein the selective etching step includes an ejection step of ejecting the etching solution created in the etching solution creation step toward the ejection port toward the substrate. Method.
The method according to any one of claims 1 to 5, further comprising, before the selective etching step, a natural oxide film removing step of supplying an oxide film removing liquid to the substrate to remove a natural oxide film of the object to be etched. 4. The substrate processing method according to 1.
The said etching object is a thin film obtained by performing a some process including the deposition process which deposits polysilicon, and the heat treatment process which heats the said polysilicon deposited in the said deposition process, The claim | item. 7. The substrate processing method according to any one of 1 to 6.
8. The method according to claim 1, wherein the etching solution forming step includes a dissolved oxygen concentration changing step of reducing a dissolved oxygen concentration of at least one of the quaternary ammonium hydroxide, the water, and the inhibitor. The substrate processing method according to claim 1.
The substrate processing method according to any one of claims 1 to 8, further comprising an atmosphere oxygen concentration changing step of reducing an oxygen concentration in an atmosphere in contact with the etching solution held on the substrate.
(10) The substrate processing method according to any one of (1) to (9), wherein the inhibitor is glycol.
The etching solution forming step is a step of forming the alkaline etching solution containing TMAH (tetramethylammonium hydroxide) as the quaternary ammonium hydroxide, the water, and propylene glycol as the glycol. The substrate processing method according to claim 10, wherein
An etching object including polysilicon, a non-etching object different from the etching object, and a substrate processing apparatus for supplying an alkaline etchant to an exposed substrate,
The alkaline etching solution containing quaternary ammonium hydroxide, water, and an inhibitor that inhibits contact between the hydroxide ion generated from the quaternary ammonium hydroxide and the object to be etched; Means for preparing an etchant to be prepared;
By supplying the etching solution created by the etching solution creating means to the substrate where the etching object and the non-etching object are exposed, the etching object is suppressed while suppressing the etching of the non-etching object. A substrate processing apparatus comprising: selective etching means for performing etching.
The etchant creating means includes a concentration determining means for determining a concentration of the inhibitor in the etchant based on a target value of a difference between etching rates on a plurality of crystal planes of the silicon single crystal constituting the polysilicon, The substrate processing apparatus according to claim 12.
14. The substrate processing apparatus according to claim 12, wherein the concentration of the inhibitor in the etching solution created by the etching solution creating unit is 20% by mass or more and less than 100% by mass.
The substrate processing apparatus according to any one of claims 12 to 14, wherein the molecule of the inhibitor is larger than the hydroxide ion.
The selective etching unit includes a discharge port that discharges the etchant created by the etchant creation unit toward the substrate,
16. The etching liquid producing means according to claim 12, further comprising a mixing means for mixing said quaternary ammonium hydroxide, said water and said inhibitor before said etching liquid is discharged from said discharge port. The substrate processing apparatus according to claim 1.
Before the etchant created by the etchant creating means is supplied to the substrate, a natural oxide film removing means for supplying an oxide film removing liquid to the substrate to remove a natural oxide film of the object to be etched is provided. The substrate processing apparatus according to any one of claims 12 to 16, further comprising:
18. The etching liquid producing means according to claim 12, wherein said etching liquid producing means includes a dissolved oxygen concentration changing means for decreasing a dissolved oxygen concentration of at least one of said quaternary ammonium hydroxide, said water and said inhibitor. The substrate processing apparatus according to claim 1.
The substrate processing apparatus according to any one of claims 12 to 18, further comprising: an atmosphere oxygen concentration changing unit that reduces an oxygen concentration in an atmosphere in contact with the etching solution held on the substrate.
(20) The substrate processing apparatus according to any one of (12) to (19), wherein the inhibitor is glycol.
The etching solution preparing means includes means for preparing the alkaline etching solution containing TMAH (tetramethylammonium hydroxide) as the quaternary ammonium hydroxide, the water, and propylene glycol as the glycol. 21. The substrate processing apparatus according to claim 20, wherein