Substrate processing solution, substrate processing method, and substrate processing apparatus

Abstract

To provide a substrate processing liquid, a substrate processing method, and a substrate processing apparatus that have excellent drying performance and can remove liquids adhering to the surface of substrates well.SOLUTION: In this invention, the substrate processing liquid has a sublimable substance, a solvent that dissolves the sublimable substance, and an auxiliary agent that is added to the solution in which the sublimable substance is dissolved in the solvent to disperse particles of the sublimable substance in the solution that exceeds solubility. Therefore, the particles of the sublimable substance exceeding the solubility in the substrate processing liquid are uniformly dispersed and dissolved in the solvent. Therefore, more sublimable substances are supplied to the patterned surface of the substrate than in the conventional technology, and a large amount of sublimable substances (solid phase) exist inside the pattern. As a result, residual solvent between patterns is effectively suppressed, and sublimation drying is executed in a situation where the pattern is firmly held by the sublimable substance (solid phase).SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a substrate processing solution used to remove a liquid adhering to a substrate by utilizing the sublimation phenomenon of a sublimable substance, a substrate processing method for removing the liquid from a substrate using the substrate processing solution, and a substrate processing apparatus. The substrates include semiconductor wafers, substrates for liquid crystal displays, substrates for flat panel displays (FPDs) such as organic electroluminescence (EL) displays, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, and substrates for solar cells. [Background technology]

[0002] Manufacturing processes for electronic components such as semiconductor devices and liquid crystal display devices include a process of forming a pattern by repeatedly performing processes such as film formation and etching on the surface of a substrate. After forming this pattern, processes such as cleaning with a chemical solution, rinsing with a rinse solution, and drying are performed in that order. As patterns become finer, the importance of drying has become particularly important. In other words, techniques for suppressing or preventing pattern collapse during drying have become important. Therefore, a substrate processing technique has been proposed in which a substrate is sublimated and dried using a substrate processing solution in which a sublimable substance such as camphor or cyclohexanone oxime is dissolved in a solvent such as IPA (isopropyl alcohol) (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-9988 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described conventional technology, the following steps are performed to remove DIW (deionized water) adhering to the surface of the substrate after the rinsing process. IPA is supplied to the surface of the substrate to replace the DIW. Then, the substrate processing liquid is spin-coated on the surface of the substrate, and the solvent (IPA) of the substrate processing liquid is evaporated. This forms a solidified film of the sublimable substance on the surface of the substrate. Finally, the solidified film is sublimated and removed from the surface of the substrate.

[0005] As described above, conventional substrate processing solutions use a solution in which a sublimable substance is dissolved in a solvent, and the concentration of the sublimable substance in the solution is low, which can cause the sublimable substance to not fully fill the gaps in the pattern. In this case, a solidified film is not formed in the gaps in the pattern, resulting in the problem of the pattern not being retained. In addition, a solidified film may be formed on the top layer of the substrate surface, and the solvent may remain in the solidified film. Due to these factors, it may not be possible to prevent pattern collapse.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a substrate processing liquid, a substrate processing method, and a substrate processing apparatus that have excellent drying performance and can effectively remove liquid adhering to the surface of a substrate. [Means for solving the problem]

[0007] A first aspect of the present invention is a substrate processing solution used to remove a liquid on a substrate having a pattern-formed surface, the substrate processing solution comprising a sublimable substance, a solvent that dissolves the sublimable substance, and a solution in which the sublimable substance is dissolved in the solvent, the solution being added to disperse particles of the sublimable substance in excess of the solubility of the sublimable substance. , increasing the concentration of particles of the sublimable substance above the saturated concentration. and an auxiliary agent.

[0008] In addition, a second aspect of the present invention is a substrate processing method comprising: a processing liquid preparation step of preparing the substrate processing liquid; a liquid film formation step of supplying the substrate processing liquid prepared in the processing liquid preparation step to a surface of a substrate on which a pattern has been formed to form a liquid film of the substrate processing liquid on the surface of the substrate; a solidified film formation step of solidifying the liquid film of the substrate processing liquid to form a solidified film of a sublimable substance; and a sublimation step of sublimating the solidified film and removing it from the surface of the substrate.

[0009] Furthermore, a third aspect of the present invention is a substrate processing apparatus characterized by comprising: a storage section for storing the substrate processing liquid; and a processing liquid supply section for supplying the substrate processing liquid stored in the storage section to a surface of a substrate on which a pattern is formed.

[0010] In the invention configured as described above, particles of the sublimable substance exceeding the solubility in the substrate processing liquid are uniformly dispersed and dissolved in the solvent. Therefore, more sublimable substance is supplied to the pattern-formed surface of the substrate than in the prior art. Moreover, since the particles of the sublimable substance are in a metastable state, when the substrate processing liquid is supplied to the pattern-formed surface of the substrate and enters between the patterns, the sublimable substance particles recrystallize between the patterns. Therefore, a large amount of sublimable substance (solid phase) exists inside the patterns. This effectively prevents solvent from remaining between the patterns, and sublimation drying is performed in a state in which the patterns are firmly held by the sublimable substance (solid phase). [Effects of the Invention]

[0011] As described above, sublimation drying can be performed in a state where residual solvent between patterns is suppressed, and liquid adhering to the surface of the substrate can be effectively removed with excellent drying performance. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 10 is a graph showing an increase in the concentration of sublimable substances in a substrate processing solution due to the addition of an auxiliary agent. [Figure 2] 1 is a plan view showing a schematic configuration of a substrate processing system equipped with a first embodiment of a substrate processing apparatus according to the present invention. [Figure 3] FIG. 3 is a side view of the substrate processing system shown in FIG. [Figure 4] 1 is a partial cross-sectional view showing the configuration of a first embodiment of a substrate processing apparatus according to the present invention. [Figure 5] FIG. 2 is a block diagram showing an electrical configuration of a control unit that controls the substrate processing apparatus. [Figure 6] FIG. 2 is a diagram showing a configuration of a processing liquid supply unit. [Figure 7] 3 is a diagram showing the contents of substrate processing performed in the substrate processing apparatus of FIG. 2. FIG. [Figure 8] 7 is a flowchart showing the operation of the refining device shown in FIG. [Figure 9A] FIG. 7 is a diagram schematically illustrating a first operation example of the refining device shown in FIG. 6. [Figure 9B] FIG. 7 is a diagram schematically illustrating a second operation example of the refining device shown in FIG. 6. [Figure 9C] FIG. 7 is a diagram schematically illustrating a third operation example of the refining device shown in FIG. 6. [Figure 9D] FIG. 7 is a diagram schematically illustrating a fourth operation example of the refining device shown in FIG. 6. [Figure 9E] FIG. 7 is a diagram schematically illustrating a fifth operation example of the refining device shown in FIG. 6. [Figure 10] FIG. 10 is a diagram showing the configuration of a substrate processing system equipped with a substrate processing apparatus according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Substrate processing solution> A substrate processing solution according to an embodiment of the present invention will be described below.

[0014] As used herein, "substrate" refers to various substrates such as semiconductor substrates, glass substrates for photomasks, glass substrates for liquid crystal displays, glass substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical disks, substrates for magnetic disks, and substrates for magneto-optical disks. Furthermore, as used herein, "pattern-formed surface" refers to a surface of a substrate on which a concave-convex pattern is formed in any region, regardless of whether it is flat, curved, or concave-convex. Furthermore, as used herein, "sublimability" refers to a property in which a simple substance, compound, or mixture undergoes a phase transition from solid to gas or from gas to solid without passing through a liquid state, and "sublimable substance" refers to a substance having such sublimability.

[0015] The substrate processing solution according to the present invention includes a sublimable substance, such as camphor or cyclohexanone oxime, which is used in sublimation drying; a solvent, such as IPA, that dissolves the sublimable substance; and an auxiliary agent, added to the solution containing the sublimable substance in the solvent, that disperses particles of the sublimable substance beyond its solubility. In this manner, in this embodiment, the auxiliary agent is added to a substrate processing solution used in conventional technology (hereinafter referred to as the "conventional substrate processing solution") to increase the concentration of sublimable substance particles uniformly dispersed in the substrate processing solution above the saturated concentration of the sublimable substance in the conventional substrate processing solution, thereby dispersing the sublimable substance particles uniformly in a so-called metastable state. In other words, the substrate processing solution according to this embodiment is a supersaturated solution of the sublimable substance. For example, when cyclohexanone oxime is used as the sublimable substance, IPA can be used as the solvent and aqueous ammonia can be used as the auxiliary agent. Hereinafter, a substrate processing solution refined by mixing cyclohexanone oxime (sublimable substance), IPA (solvent), and aqueous ammonia (auxiliary agent) will be described with reference to FIG.

[0016] Before describing the substrate processing solution, the solubility of cyclohexanone oxime in IPA will be described. Patent Document 2 describes a substrate processing solution in which cyclohexanone oxime is dissolved in IPA. More specifically, it exemplifies sublimation drying using a substrate processing solution containing 0.1 vol% (0.13 wt%) to 10 vol% (12.97 wt%) of cyclohexanone oxime. These conventional substrate processing solutions have good solubility. As described in Patent Document 2, this "solubility" means that, for example, 10 g or more of cyclohexanone oxime dissolves in 100 g of solvent at 23°C. Furthermore, "room temperature" means a temperature range of 5°C to 35°C.

[0017] However, there is no clear description of the solubility of cyclohexanone oxime, i.e., the limit amount of cyclohexanone oxime that can be dissolved in a certain amount of IPA. Therefore, the inventors of the present invention poured 4 g of cyclohexanone oxime into transparent glass containers containing different amounts of IPA, stirred until thoroughly mixed, and then allowed each transparent glass container to stand to check for precipitation. As a result, it was found that 8.3 ml of IPA was required to dissolve 4 g of cyclohexanone oxime to a saturated state. In other words, the above demonstration experiment revealed that the saturated concentration of cyclohexanone oxime in the substrate processing solution was approximately 38 wt%.

[0018] In a solution in which cyclohexanone oxime is dissolved at its limiting concentration, i.e., a saturated solution, dissolution equilibrium is established. In other words, the dissolution reaction in which cyclohexanone oxime (solid phase) dissolves and the reaction in which cyclohexanone oxime particles dispersed in the solution crystallize appear to be stopped, but in reality, dissolution and recrystallization occur at the same rate. Therefore, if an auxiliary agent that inhibits crystallization (crystallization inhibitor) is added to the solution, the rate of recrystallization slows. The present inventors have reasoned that this disrupts the dissolution equilibrium, resulting in a metastable solution in which the concentration of cyclohexanone oxime particles is higher than the saturated concentration, i.e., a supersaturated solution of cyclohexanone oxime.

[0019] Furthermore, adjusting the pH of the solution gives the cyclohexanone oxime particles a negative zeta potential, increasing the repulsive force between the cyclohexanone oxime particles. As a result, crystallization is inhibited. Based on these considerations, the present inventors selected ammonia water as an example of a pH adjuster that negatively adjusts the zeta potential of the cyclohexanone oxime particles, i.e., the "auxiliary agent" of the present invention. As shown in FIG. 1, it was confirmed that by using ammonia water as the auxiliary agent, the concentration of cyclohexanone oxime particles in the substrate processing solution is higher than the saturated concentration, resulting in a metastable state. Note that the auxiliary agent is not limited to ammonia water, and any pH adjuster that negatively adjusts the zeta potential of the cyclohexanone oxime particles can be used.

[0020] FIG. 1 shows the increase in concentration of a sublimable substance in a substrate processing solution due to the addition of an auxiliary agent. In the figure, "Oxime" indicates the weight of cyclohexanone oxime, which is an example of a "sublimable substance" of the present invention; "IPA" indicates the amount of IPA, which is an example of a "solvent" of the present invention; and "NH4OH" indicates the amount of ammonia water, which is an example of an "auxiliary agent" of the present invention. Cyclohexanone oxime, IPA (and ammonia water) are stirred and mixed in a transparent glass container GC to produce a substrate processing solution L. The transparent glass container GC is then allowed to stand, and the dissolved state of cyclohexanone oxime is schematically shown. Note that "wt%" in the figure indicates the weight percent of cyclohexanone oxime in the substrate processing solution. Furthermore, the hatched solid OX in the "dissolved state" indicates cyclohexanone oxime (solid phase).

[0021] Here, a solution was prepared by dissolving 2 g of solid cyclohexanone oxime OX in 2 ml of IPA. As shown in column (a) of the figure, this solution contains 55.9 wt% cyclohexanone oxime, exceeding the saturated concentration (38 wt%). Therefore, a large amount of solid cyclohexanone oxime OX remains in the transparent glass container GC. When ammonia water is added to a solution with the same composition as this solution, the amount of solid cyclohexanone oxime OX remaining decreases as the amount of ammonia water added increases, as shown in columns (b) to (d) of the figure. When 0.3 ml of ammonia water is added, 2 g of solid cyclohexanone oxime OX is completely dissolved. A substrate processing solution L containing 52.06 wt% cyclohexanone oxime is produced. This means that cyclohexanone oxime particles are uniformly dispersed in the substrate processing solution L at a concentration approximately 4 to 400 times higher than that of the substrate processing solution described in Patent Document 2 (cyclohexanone oxime 0.13 wt % to cyclohexanone oxime 12.97 wt %). Thus, the substrate processing solution L containing a high concentration of cyclohexanone oxime particles is obtained. Therefore, as described below, after the substrate processing solution L is spin-coated onto the pattern-formed surface of the substrate, the solvent (IPA) of the substrate processing solution is evaporated. Furthermore, since the substrate processing solution according to the present invention is a supersaturated solution of cyclohexanone oxime and is in a so-called metastable state, recrystallization of cyclohexanone oxime particles begins immediately after spin-coating. Due to this recrystallization and solvent evaporation, more cyclohexanone oxime (solid phase) penetrates into the gaps in the pattern than when a conventional substrate processing solution is used. As a result, the substrate processing solution has excellent drying performance, allowing for effective removal of liquid adhering to the substrate surface.

[0022] In this embodiment, cyclohexanone oxime is used as the sublimable substance, but the same applies when other sublimable substances for sublimation drying, such as camphor, are used. Furthermore, while IPA is used as the solvent, any solvent capable of dissolving the sublimable substance may be used, and as described in Patent Document 1, for example, it may be at least one selected from the group consisting of alcohols, ketones, ethers, cycloalkanes, and water. Furthermore, while aqueous ammonia is used as the auxiliary agent, a crystallization inhibitor can also be used, which adjusts the pH of the solution in which the sublimable substance is dissolved in the solvent to inhibit recrystallization of particles of the sublimable substance dissolved in the solvent.

[0023] <Single-wafer substrate processing system> Next, a substrate processing system equipped with a substrate processing apparatus for processing a substrate having a pattern-formed surface using the substrate processing liquid (=sublimable substance+solvent+auxiliary agent) will be described.

[0024] FIG. 2 is a plan view showing a schematic configuration of a substrate processing system equipped with a first embodiment of a substrate processing apparatus according to the present invention. FIG. 3 is a side view of the substrate processing system shown in FIG. 2. These drawings do not show the external appearance of the apparatus, but are schematic views clearly showing the internal structure of the substrate processing system 100 by excluding the outer wall panels and other components. The substrate processing system 100 is a single-wafer processing apparatus installed, for example, in a clean room, for processing substrates W, each of which has a circuit pattern or the like (equivalent to an example of the above-mentioned "pattern") formed on only one main surface. A first embodiment of a substrate processing method according to the present invention is executed in the substrate processing system 100. In this specification, the pattern-formed surface (one main surface) on which the pattern is formed is referred to as the "front surface Wf," and the opposite main surface on which the pattern is not formed is referred to as the "back surface Wb." The surface facing downward is referred to as the "lower surface," and the surface facing upward is referred to as the "upper surface." The following description will be primarily based on a substrate processing system used for processing semiconductor wafers, but the present invention is equally applicable to processing the various types of substrates listed above.

[0025] 2, the substrate processing system 100 includes a substrate processing unit 110 that processes substrates W, and an indexer unit 120 coupled to the substrate processing unit 110. The indexer unit 120 includes a container holder 121 that can hold a plurality of containers C for accommodating substrates W (such as a FOUP (Front Opening Unified Pod), an SMIF (Standard Mechanical Interface) pod, or an OC (Open Cassette) that accommodates a plurality of substrates W in a sealed state), and an indexer robot 122 that accesses the containers C held by the container holder 121 to remove unprocessed substrates W from the container C or store processed substrates W in the container C. Each container C accommodates a plurality of substrates W in a substantially horizontal position.

[0026] The indexer robot 122 comprises a base 122a fixed to the apparatus housing, an articulated arm 122b rotatable about a vertical axis relative to the base 122a, and a hand 122c attached to the tip of the articulated arm 122b. The hand 122c is structured so that a substrate W can be placed on its upper surface and held thereon. Indexer robots having such articulated arms and hands for holding substrates are well known, and therefore a detailed description thereof will be omitted.

[0027] The substrate processing section 110 includes a substrate transfer robot 111 disposed approximately in the center in a plan view, and a plurality of substrate processing apparatuses 1 disposed to surround the substrate transfer robot 111. Specifically, a plurality of (eight in this example) substrate processing apparatuses 1 are disposed facing the space in which the substrate transfer robot 111 is disposed. The substrate transfer robot 111 randomly accesses these substrate processing apparatuses 1 to hand over substrates W. Meanwhile, each substrate processing apparatus 1 performs a predetermined process on the substrate W. In this embodiment, these substrate processing apparatuses 1 have the same functions. This enables parallel processing of multiple substrates W.

[0028] <Configuration of substrate processing apparatus 1> Fig. 4 is a partial cross-sectional view showing the configuration of a first embodiment of a substrate processing apparatus according to the present invention. Fig. 5 is a block diagram showing the electrical configuration of a control unit that controls the substrate processing apparatus. In this embodiment, a control unit 4 is provided for each substrate processing apparatus 1, but a single control unit may be configured to control multiple substrate processing apparatuses 1. Alternatively, the substrate processing apparatuses 1 may be controlled by a control unit (not shown) that controls the entire substrate processing system 100.

[0029] The substrate processing apparatus 1 includes a chamber 2 having an internal space 21 and a spin chuck 3 accommodated in the internal space 21 of the chamber 2 and holding a substrate W. As shown in FIGS. 2 and 3, a shutter 23 is provided on a side surface of the chamber 2. A shutter opening / closing mechanism 22 (FIG. 5) is connected to the shutter 23 and opens and closes the shutter 23 in response to an opening / closing command from the control unit 4. More specifically, in the substrate processing apparatus 1, when an unprocessed substrate W is loaded into the chamber 2, the shutter opening / closing mechanism 22 opens the shutter 23, and the unprocessed substrate W is loaded face-up onto the spin chuck 3 by the hand of the substrate transfer robot 111. That is, the substrate W is placed on the spin chuck 3 with its front surface Wf facing upward. After the substrate W is loaded, when the hand of the substrate transfer robot 111 retreats from the chamber 2, the shutter opening / closing mechanism 22 closes the shutter 23. Then, as described below, chemical solutions, DIW, IPA, a substrate processing liquid for sublimation drying, and nitrogen gas are supplied to the surface Wf of the substrate W within the internal space 21 of the chamber 2, and the desired substrate processing is performed in a room temperature environment. After the substrate processing is completed, the shutter opening / closing mechanism 22 opens the shutter 23 again, and the hand of the substrate transport robot 111 removes the processed substrate W from the spin chuck 3. In this way, in this embodiment, the internal space 21 of the chamber 2 functions as a processing space in which substrate processing is performed while maintaining a room temperature environment.

[0030] The spin chuck 3 includes a plurality of chuck pins 31 for gripping the substrate W, a spin base 32 formed in a disk shape extending horizontally and supporting the plurality of chuck pins 31, a central shaft 33 connected to the spin base 32 and rotatable about a rotation axis C1 parallel to a surface normal extending from the center of the surface of the substrate W, and a substrate rotation drive mechanism 34 that rotates the central shaft 33 about the rotation axis C1 using a motor. The plurality of chuck pins 31 are provided on the periphery of the upper surface of the spin base 32. In this embodiment, the chuck pins 31 are arranged at equal intervals in the circumferential direction. When the motor of the substrate rotation drive mechanism 34 is activated in response to a rotation command from the control unit 4 while the substrate W placed on the spin chuck 3 is gripped by the chuck pins 31, the substrate W rotates about the rotation axis C1. Furthermore, while the substrate W is being rotated in this manner, chemical liquid, IPA, DIW, substrate processing liquid and nitrogen gas are sequentially supplied onto the surface Wf of the substrate W from nozzles provided in the atmosphere blocking mechanism 5 in response to a supply command from the control unit 4.

[0031] The atmosphere shutoff mechanism 5 includes a shutoff plate 51, an upper spin shaft 52 rotatably mounted on the shutoff plate 51, and a nozzle 53 vertically penetrating the center of the shutoff plate 51. The shutoff plate 51 is finished in a circular disk shape with a diameter substantially equal to or greater than that of the substrate W. The shutoff plate 51 is disposed opposite, with a gap therebetween, the upper surface of the substrate W held by the spin chuck 3. Therefore, the lower surface of the shutoff plate 51 functions as a circular substrate-facing surface 51a that faces the entire front surface Wf of the substrate W. Furthermore, a cylindrical through-hole 51b that vertically penetrates the shutoff plate 51 is formed in the center of the substrate-facing surface 51a.

[0032] The upper spin shaft 52 is rotatably provided about a rotation axis (coincident with the rotation axis C1 of the substrate W) that passes through the center of the shielding plate 51 and extends vertically. The upper spin shaft 52 has a cylindrical shape. The inner peripheral surface of the upper spin shaft 52 is formed into a cylindrical surface centered on the rotation axis. The internal space of the upper spin shaft 52 communicates with the through-hole 51b of the shielding plate 51. The upper spin shaft 52 is supported by a support arm 54 that extends horizontally above the shielding plate 51 so as to be rotatable relative to the support arm 54.

[0033] The nozzle 53 is disposed above the spin chuck 3. The nozzle 53 is supported by the support arm 54 in a state where it cannot rotate relative to the support arm 54. The nozzle 53 can be raised and lowered integrally with the shielding plate 51, the upper spin shaft 52, and the support arm 54. A discharge port 53a is provided at the lower end of the nozzle 53, and faces the center of the front surface Wf of the substrate W held by the spin chuck 3.

[0034] A shielding plate rotation drive mechanism 55 (FIG. 5) including an electric motor and the like is coupled to the shielding plate 51. The shielding plate rotation drive mechanism 55 rotates the shielding plate 51 and the upper spin shaft 52 relative to the support arm 54 about the rotation axis C1 in response to a rotation command from the control unit 4. A shielding plate lift drive mechanism 56 is coupled to the support arm 54. The shielding plate lift drive mechanism 56 lifts and lowers the shielding plate 51, the upper spin shaft 52, and the nozzle 53 integrally with the support arm 54 in the vertical direction Z in response to a lift command from the control unit 4. More specifically, the shielding plate lift drive mechanism 56 lifts and lowers the shielding plate 51, the upper spin shaft 52, and the nozzle 53 together with the support arm 54 between a blocking position (position shown in FIG. 4) where the substrate facing surface 51a is close to the front surface Wf of the substrate W held on the spin chuck 3 and substantially blocks the space above the front surface Wf from the ambient atmosphere, and a retracted position retracted significantly above the blocking position.

[0035] The upper end of the nozzle 53 is connected to a chemical liquid supply unit 61 , a rinse liquid supply unit 62 , an organic solvent supply unit 63 , a processing liquid supply unit 64 and a gas supply unit 65 .

[0036] The chemical supply unit 61 has a chemical pipe 611 connected to the nozzle 53 and a valve 612 installed in the chemical pipe 611. The chemical pipe 611 is connected to a chemical supply source. In this embodiment, the chemical may be any chemical that has the function of cleaning the surface Wf of the substrate W. For example, an acidic chemical may be used, such as a chemical containing at least one of hydrofluoric acid (HF), hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid. Furthermore, an alkaline chemical may be used, such as a chemical containing at least one of ammonia and a hydroxyl group. In this embodiment, hydrofluoric acid is used as the chemical. Therefore, when the valve 612 is opened in response to an opening / closing command from the control unit 4, the hydrofluoric acid chemical is supplied to the nozzle 53 and discharged from the discharge port 53a toward the center of the surface of the substrate W.

[0037] The rinse liquid supply unit 62 has a rinse liquid pipe 621 connected to the nozzle 53 and a valve 622 installed in the rinse liquid pipe 621. The rinse liquid pipe 621 is connected to a rinse liquid supply source. In this embodiment, DIW is used as the rinse liquid, and when the valve 622 is opened in response to an opening / closing command from the control unit 4, the DIW is supplied to the nozzle 53 and discharged from the discharge port 53a toward the center of the surface of the substrate W. Note that, other than DIW, any of carbonated water, electrolytic ion water, hydrogen water, ozone water, and diluted hydrochloric acid water (for example, about 10 ppm to 100 ppm) may be used as the rinse liquid.

[0038] The organic solvent supply unit 63 is a unit for supplying an organic solvent as a low-surface-tension liquid having a specific gravity greater than that of air and a surface tension lower than that of water. The organic solvent supply unit 63 has an organic solvent pipe 631 connected to the nozzle 53 and a valve 632 attached to the organic solvent pipe 631. The organic solvent pipe 631 is connected to a supply source of the organic solvent. In this embodiment, IPA is used as the organic solvent. When the valve 632 is opened in response to an opening / closing command from the control unit 4, IPA is supplied to the nozzle 53 and ejected from the ejection port 53a toward the center of the surface of the substrate W. In addition to IPA, other organic solvents that can be used include, for example, methanol, ethanol, acetone, EG (ethylene glycol), and HFE (hydrofluoroether). The organic solvent may be composed of only a single component, or may be a liquid mixed with other components. For example, it may be a mixture of IPA and acetone, or a mixture of IPA and methanol.

[0039] The processing liquid supply unit 64 is a unit that supplies a substrate processing liquid for sublimation drying, which functions as a drying auxiliary liquid when drying the substrate W held on the spin chuck 3, to the front surface Wf of the substrate W. The processing liquid supply unit 64 has a processing liquid pipe 641 connected to the nozzle 53 and a valve 642 interposed in the processing liquid pipe 641. The processing liquid pipe 641 is connected to a processing liquid supply part that functions as a supply source of the substrate processing liquid for sublimation drying described above.

[0040] 6 is a diagram showing the configuration of the processing liquid supply unit. Processing liquid supply unit 400 includes a refinement device 500 that refines the substrate processing liquid, and a storage tank 401 that stores the substrate processing liquid refined by refinement device 500. Note that storage tank 401 is equipped with an ultrasonic wave applying unit 402 having a vibrator that generates ultrasonic waves. When ultrasonic wave applying unit 402 is activated in response to a vibration command from control unit 4, ultrasonic vibrations are applied to the substrate processing liquid stored in storage tank 401.

[0041] The purification apparatus 500 removes particles from used substrate processing liquid or from an undiluted substrate processing liquid provided by a chemical liquid manufacturer, and purifies the substrate processing liquid into a highly pure supersaturated solution of cyclohexanone oxime. Here, "used substrate processing liquid" refers to the substrate processing liquid recovered from the substrate W using a cup during spin coating, as will be described later. "Undiluted substrate processing liquid provided by a chemical liquid manufacturer" refers to a cyclohexanone oxime solution (e.g., a 3 wt % cyclohexanone oxime solution) prepared by the chemical liquid manufacturer, in which cyclohexanone oxime is dissolved in IPA.

[0042] In order to send the substrate processing liquid (= sublimable substance + solvent + auxiliary agent) refined by the refinement device 500 to the storage tank 401, the refinement device 500 and the storage tank 401 are connected by a pipe 403 having a filter 404 interposed therebetween. Therefore, while the substrate processing apparatus 1 is operating, the refinement device 500 also operates in parallel, and the substrate processing liquid for sublimation drying is intermittently refined and sent to the storage tank 401 via the pipe 403. The storage tank 401 then stores the refined substrate processing liquid. The configuration and refining operation of the refinement device 500 will be described in detail after the substrate processing method is explained.

[0043] The bottom of the storage tank 401 is connected to a processing liquid pipe 641 by a pipe 405. A pump 406, a valve 407, and a filter 408 are installed in this pipe 405. Therefore, when the pump 406 is operated and the valve 407 is opened based on a control command from the control unit 4, the substrate processing liquid is sent from the processing liquid supply unit 400 toward the nozzle 53. As a result, while the valve 642 is open, the substrate processing liquid (a supersaturated solution of cyclohexanone oxime) is supplied from the nozzle 53 to the surface Wf of the substrate W.

[0044] 6, an ultrasonic vibration applying unit is provided along the supply path (pipe 405, processing liquid pipe 641, and nozzle 53) of the substrate processing liquid from the storage tank 401. Therefore, ultrasonic vibration is continuously applied to the substrate processing liquid until it is supplied to the substrate W, and the metastable state is maintained, that is, crystallization of cyclohexanone oxime particles contained in the substrate processing liquid is effectively suppressed. As a result, the substrate processing liquid in a metastable state can be reliably supplied to the surface Wf of the substrate W. Note that the manner in which ultrasonic vibration is applied to the substrate processing liquid is arbitrary; for example, a vibrator may be built into the nozzle 53. Alternatively, a vibrator may be provided adjacent to the nozzle 53.

[0045] 4, when the substrate processing liquid is sent toward the nozzle 53 in the above-described manner, the substrate processing liquid is discharged from the discharge port 53a of the nozzle 53 toward the center of the surface of the substrate W.

[0046] The gas supply unit 65 has a gas supply pipe 651 connected to the nozzle 53 and a valve 652 for opening and closing the gas supply pipe 651. The gas supply pipe 651 is connected to a gas supply source. In this embodiment, dehumidified nitrogen gas is used as the gas, and when the valve 652 is opened in response to an opening / closing command from the control unit 4, the nitrogen gas is supplied to the nozzle 53 and sprayed from the outlet 53a toward the center of the surface of the substrate W. Note that, instead of nitrogen gas, an inert gas such as dehumidified argon gas may be used as the gas.

[0047] The substrate processing apparatus 1 is provided with an exhaust tub 80 surrounding the spin chuck 3. Also provided are a plurality of cups 81, 82 (first cup 81 and second cup 82) disposed between the spin chuck 3 and the exhaust tub 80, and a plurality of guards 84-86 (first guard 84 to third guard 86) for receiving processing liquid splashed around the substrate W. Guard lifting / lowering drive mechanisms 87-89 (first to third guard lifting / lowering drive mechanisms 87-89) are connected to the guards 84-86, respectively. The guard lifting / lowering drive mechanisms 87-89 independently raise and lower the guards 84-86 in response to lifting / lowering commands from the control unit 4. The first guard lifting / lowering drive mechanism 87 is not shown in FIG. 4. Of the three guards, the second guard 85 faces the peripheral edge of the substrate W during spin coating with the substrate processing liquid (a liquid film forming step S6-1, which will be described later). Therefore, the substrate processing liquid shaken off from the substrate W is captured by the second guard 85 and recovered in the second cup 82. The recovered substrate processing liquid is then sent to the refining device 500 via the recovery pipe 821, where it is refined and then reused.

[0048] The control unit 4 has an arithmetic unit such as a CPU, a storage unit such as a fixed memory device or a hard disk drive, and an input / output unit. The storage unit stores a program executed by the arithmetic unit. The control unit 4 controls each part of the apparatus in accordance with the program, thereby performing the substrate processing shown in FIG. 7 using a metastable substrate processing solution in which cyclohexanone oxime is dissolved to a supersaturated state.

[0049] <Substrate processing method> Next, a substrate processing method using the substrate processing system 100 shown in Fig. 2 will be described with reference to Fig. 7. Fig. 7 is a diagram showing the contents of the substrate processing performed in the substrate processing apparatus of Fig. 2. In Fig. 7, a flowchart of the substrate processing performed in one substrate processing apparatus 1 is shown on the left side. In addition, the upper right, middle right, and lower right sections are schematic diagrams of a liquid film forming process, a solidified film forming process, and a sublimation process, respectively, and an enlarged view of a portion of the surface Wf of the substrate W. However, for ease of understanding, the dimensions and number of each part are exaggerated or simplified as necessary.

[0050] The processing object in the substrate processing system 100 is, for example, a silicon wafer, and an uneven pattern PT is formed on the surface Wf, which is the pattern formation surface. In this embodiment, the protrusions PT1 have a height in the range of 100 to 600 nm and a width in the range of 5 to 50 nm. The shortest distance between two adjacent protrusions PT1 (the shortest width of the recess) is in the range of 5 to 150 nm. The aspect ratio of the protrusions PT1, i.e., the value obtained by dividing the height by the width (height H / width WD), is in the range of 5 to 35.

[0051] The pattern PT may also be a pattern in which line-shaped patterns formed by minute trenches are repeatedly arranged. The pattern PT may also be formed by providing a plurality of minute holes (voids or pores) in a thin film. The pattern PT includes, for example, an insulating film. The pattern PT may also include a conductive film. More specifically, the pattern PT is formed of a laminated film in which a plurality of films are stacked, and may further include an insulating film and a conductive film. The pattern PT may also be a pattern composed of a single layer film. The insulating film may be a silicon oxide film or a silicon nitride film. The conductive film may be an amorphous silicon film doped with impurities to reduce resistance, or may be a metal film (e.g., a TiN film). The pattern PT may also be formed in the front end or the back end. The pattern PT may also be a hydrophobic film or a hydrophilic film. An example of a hydrophilic film is a TEOS film (a type of silicon oxide film).

[0052] 7 are performed in an atmospheric pressure environment unless otherwise specified. Here, the atmospheric pressure environment refers to an environment of 0.7 atmospheres or more and 1.3 atmospheres or less, with the standard atmospheric pressure (1 atmosphere, 1013 hPa) at the center. In particular, when the substrate processing system 100 is placed in a clean room with a positive pressure, the environment of the surface Wf of the substrate W becomes higher than 1 atmosphere.

[0053] Before an unprocessed substrate W is loaded into the substrate processing apparatus 1, the control unit 4 issues commands to each unit of the apparatus to set the substrate processing apparatus 1 to its initial state. That is, the shutter 23 (FIGS. 2 and 3) is closed by the shutter opening / closing mechanism 22. The spin chuck 3 is positioned and stopped at a position suitable for loading the substrate W by the substrate rotation drive mechanism 34, and the chuck pins 31 are opened by a chuck opening / closing mechanism (not shown). The shielding plate 51 is positioned at a retracted position by the shielding plate lifting / lowering drive mechanism 56, and rotation of the shielding plate 51 by the shielding plate rotation drive mechanism 55 is stopped. All of the guards 84 to 86 have been moved downward and positioned. Furthermore, all of the valves 612, 622, 632, 642, and 652 are closed.

[0054] When an unprocessed substrate W is transported by the substrate transport robot 111, the shutter 23 opens. In synchronization with the opening of the shutter 23, the substrate W is transported into the internal space 21 of the chamber 2 by the substrate transport robot 111 and transferred to the spin chuck 3 with the front surface Wf facing upward. Then, the chuck pins 31 are closed, and the substrate W is held by the spin chuck 3 (Step S1: Transporting the Substrate).

[0055] After the substrate W is loaded, the substrate transport robot 111 retreats to the outside of the chamber 2, and the shutter 23 closes again. Then, the control unit 4 controls the motor of the substrate rotation drive mechanism 34 to rotate the spin chuck 3 at a predetermined processing speed (within a range of approximately 10 to 3000 rpm, for example, 800 to 1200 rpm). ) and maintains that processing speed. The control unit 4 also controls the shielding plate lifting drive mechanism 56 to lower the shielding plate 51 from the retracted position to the shielding position (step S2). The control unit 4 also controls the guard lifting drive mechanisms 87 to 89 to raise the first guard 84 to the third guard 86 to their upper positions, thereby positioning the first guard 84 opposite the peripheral edge surface of the substrate W.

[0056] When the rotation of the substrate W reaches the processing speed, the control unit 4 then opens the valve 612. This causes a chemical liquid (HF in this embodiment) to be discharged from the discharge port 53a of the nozzle 53 and supplied to the front surface Wf of the substrate W. On the front surface Wf of the substrate W, the HF is subjected to centrifugal force due to the rotation of the substrate W and moves to the peripheral edge of the substrate W. As a result, the entire front surface Wf of the substrate W is subjected to chemical cleaning with HF (step S3). At this time, the HF that has reached the peripheral edge of the substrate W is discharged from the peripheral edge to the side of the substrate W, received by the inner wall of the first guard 84, and sent to a waste liquid treatment facility outside the apparatus along a drainage path (not shown). This chemical cleaning with the supplied HF continues for a predetermined cleaning time, after which the control unit 4 closes the valve 612 to stop the discharge of HF from the nozzle 53.

[0057] Following the chemical cleaning, a rinse process using a rinse liquid (DIW) is performed (step S4). During this DIW rinse, the control unit 4 opens the valve 622 while maintaining the positions of the first guard 84 to the third guard 86. As a result, DIW is supplied as a rinse liquid from the outlet 53a of the nozzle 53 to the center of the front surface Wf of the substrate W that has been subjected to the chemical cleaning process. The DIW is then moved to the periphery of the substrate W by centrifugal force due to the rotation of the substrate W. As a result, HF adhering to the substrate W is washed away by the DIW. At this time, the DIW discharged from the periphery of the substrate W is discharged from the periphery of the substrate W to the side of the substrate W and, like HF, is sent to a waste liquid treatment facility outside the apparatus. This DIW rinse continues for a predetermined rinse time. After this time has elapsed, the control unit 4 closes the valve 622 to stop the discharge of DIW from the nozzle 53.

[0058] After the DIW rinse is completed, a replacement process using an organic solvent (IPA in this embodiment) having a surface tension lower than that of the DIW is performed (step S5). In the IPA replacement, the control unit 4 controls the guard lifting / lowering drive mechanisms 87 and 88 to lower the first guard 84 and the second guard 85 to their lower positions, thereby causing the third guard 86 to face the peripheral edge surface of the substrate W. Then, the control unit 4 opens the valve 632. As a result, IPA is discharged as a low-surface-tension liquid from the discharge port 53a of the nozzle 53 toward the center of the front surface Wf of the substrate W to which the DIW is attached. The IPA supplied to the front surface Wf of the substrate W is subjected to centrifugal force due to the rotation of the substrate W and spreads over the entire front surface Wf of the substrate W. As a result, the DIW (rinse liquid) attached to the front surface Wf of the substrate W is replaced with IPA over the entire front surface Wf of the substrate W. The IPA moving on the surface Wf of the substrate W is discharged from the peripheral edge of the substrate W to the side of the substrate W, received by the inner wall of the third guard 86, and sent to a recovery facility along a recovery path (not shown). This IPA replacement continues for a predetermined replacement time, and when that time has elapsed, the control unit 4 closes the valve 632 to stop the discharge of IPA from the nozzle 53.

[0059] After the IPA substitution, a sublimation drying step (step S6) corresponding to the first embodiment of the substrate processing method of the present invention is performed. This sublimation drying step includes a liquid film formation step (step S6-1) of forming a liquid film of the substrate processing liquid, a solidified film formation step (step S6-2) of solidifying the liquid film of the substrate processing liquid to form a solidified film of cyclohexanone oxime, and a sublimation step (step S6-3) of sublimating the solidified film and removing it from the surface Wf of the substrate W.

[0060] In step S6-1, the control unit 4 controls the second guard lifting / lowering drive mechanism 88 to raise the second guard 85 to the upper position, thereby causing the second guard 85 to face the peripheral edge surface of the substrate W. Then, the control unit 4 opens the valve 642. As a result, as shown in the upper right diagram of FIG. 7 , the substrate processing liquid (a supersaturated solution of cyclohexanone oxime) is discharged as a drying auxiliary liquid from the discharge port 53a of the nozzle 53 toward the center of the surface Wf of the substrate W to which the IPA is attached, and is supplied to the surface Wf of the substrate W. The substrate processing liquid on the surface Wf of the substrate W is subjected to centrifugal force due to the rotation of the substrate W and spreads over the entire surface Wf of the substrate W. As a result, the IPA attached to the surface Wf of the substrate W is replaced by the substrate processing liquid over the entire surface Wf of the substrate W, and a liquid film LF of the substrate processing liquid is formed on the surface Wf, as shown in the upper right diagram of FIG. 7 . The substrate processing liquid shaken off from the substrate W is collected by the second guard 85 and recovered in the second cup 82. The recovered substrate processing liquid is then sent to the refining device 500 via the recovery pipe 821. The refining process of the substrate processing liquid by the refining device 500 will be described in detail later.

[0061] A portion of the substrate processing solution that has spread over the entire surface Wf of the substrate W penetrates into the pattern PT. However, this embodiment differs significantly from the invention described in Patent Document 2 in the following respect: The concentration of cyclohexanone oxime particles uniformly dispersed in the substrate processing solution that has penetrated into the pattern PT is high. More specifically, this concentration is four to 400 times higher than that of the invention described in Patent Document 2. Furthermore, since the cyclohexanone oxime particles are uniformly dispersed in the substrate processing solution at a concentration exceeding the solubility limit, i.e., the substrate processing solution is in a metastable state, recrystallization of the cyclohexanone oxime particles begins once the particles penetrate into the pattern PT and flow diffusion decreases. Furthermore, in this embodiment, the recrystallization is further promoted by evaporation of the solvent component in the substrate processing solution, i.e., IPA, due to rotation of the substrate W and the subsequent supply of nitrogen gas (step S6-2).

[0062] Even after the metastable state is resolved, the rotation of the substrate W and the supply of nitrogen gas continue. That is, in step S6-2, the control unit 4 opens the valve 652, and dehumidified nitrogen gas is discharged toward the surface Wf of the substrate W, which is rotating and covered with the liquid film LF of the substrate processing liquid, as shown in the middle right of FIG. 7 . As a result, a high-concentration solidified film SF of cyclohexanone oxime is formed within the pattern PT. The timing for opening the valve 652, i.e., the timing for starting the discharge of nitrogen gas, may be either before or after the start of recrystallization of cyclohexanone oxime particles. Although the discharge of nitrogen gas is not essential for forming a solidified film of cyclohexanone oxime, it is desirable to use the discharge of nitrogen gas in combination to improve throughput.

[0063] Next, the control unit 4 executes the sublimation step (step S6-3). The control unit 4 controls the second guard lifting / lowering drive mechanism 88 to lower the second guard 85 to the lower position, thereby positioning the third guard 86 opposite the peripheral edge surface of the substrate W. In this embodiment, the control unit 4 maintains the rotation speed of the substrate W from the solidified film SF formation step (step S6-2), but may also accelerate it to a high speed. The control unit 4 also controls the shielding plate rotation drive mechanism 55 to rotate the shielding plate 51 in the same direction and at the same speed as the rotation of the substrate W. As the substrate W rotates, the contact speed between the solidified film SF and the surrounding atmosphere increases. This accelerates the sublimation of the solidified film SF, enabling the solidified film SF to be sublimated within a short period of time. However, the rotation of the shielding plate 51 is not a required component of the sublimation step and is an optional component.

[0064] Furthermore, in the sublimation step S6-3, the control unit 4 maintains the valve 652 open from the formation of the solidified film SF, and dehumidified nitrogen gas is discharged from the outlet 53a of the nozzle 53 toward the center of the surface Wf of the rotating substrate W, as shown in the lower right of FIG. 7 . This allows the sublimation step to be performed while maintaining a low humidity in the shielded space between the surface Wf of the substrate W and the substrate-facing surface 51a of the shielding plate 51. In this sublimation step S6-3, heat of sublimation is removed as the solidified film SF sublimes, maintaining the solidified film SF at or below the freezing point (melting point) of cyclohexanone oxime. This effectively prevents the sublimable substance constituting the solidified film SF, i.e., cyclohexanone oxime, from melting. Because no liquid phase exists between the patterns PT on the surface Wf of the substrate W, the substrate W can be dried while mitigating the problem of the patterns PT collapsing.

[0065] When a predetermined sublimation time has elapsed since the start of the sublimation drying step S6, in step S7, the control unit 4 controls the motor of the substrate rotation drive mechanism 34 to stop the rotation of the spin chuck 3. The control unit 4 also controls the shielding plate rotation drive mechanism 55 to stop the rotation of the shielding plate 51, and controls the shielding plate lift drive mechanism 56 to lift the shielding plate 51 from the shielding position to position it at the retracted position. The control unit 4 also controls the third guard lift drive mechanism 89 to lower the third guard 86, and retracts all of the guards 86 to 88 downward from the peripheral edge surface of the substrate W.

[0066] Thereafter, the control unit 4 controls the shutter opening / closing mechanism 22 to open the shutter 23 (FIGS. 2 and 3), and then the substrate transfer robot 111 enters the internal space of the chamber 2 and transfers the processed substrate W, which has been released from the chuck pins 31, out of the chamber 2 (step S8). Note that, once the transfer of the substrate W is completed and the substrate transfer robot 111 moves away from the substrate processing apparatus 1, the control unit 4 controls the shutter opening / closing mechanism 22 to close the shutter 23.

[0067] As described above, in this embodiment, like the invention described in Patent Document 1, the substrate W is dried using cyclohexanone oxime, which is one of the sublimable substances used for sublimation drying. However, the cyclohexanone oxime (solid phase) present inside the pattern PT is significantly different. That is, in this embodiment, a large amount of cyclohexanone oxime (solid phase) is present inside the pattern PT, effectively suppressing the remaining solvent component (IPA). In other words, sublimation drying is performed in a state where the pattern PT is firmly held by cyclohexanone oxime (solid phase). Therefore, it is possible to suppress the occurrence of pattern collapse more effectively than in the invention described in Patent Document 2.

[0068] In this embodiment, the substrate processing liquid shaken off from the substrate W is collected in the second cup 82, and the collected substrate processing liquid is purified by the purification device 500 and reused. In other words, the amount of cyclohexanone oxime used, which is relatively expensive, can be reduced, and running costs can be reduced.

[0069] Furthermore, as will be described below, the purification apparatus 500 increases the purity of cyclohexanone oxime by utilizing the recrystallization of cyclohexanone oxime particles in a metastable state, thereby reducing the number of particles contained in the substrate processing solution and further reducing the occurrence of pattern collapse.

[0070] <Purification equipment> When a substrate processing solution containing metastable cyclohexanone oxime particles is left standing, the excess cyclohexanone oxime particles recrystallize. For example, when a transparent glass container (GC) containing a substrate processing solution with the composition shown in column (d) of Figure 1 is left standing at room temperature, cyclohexanone oxime precipitates in the transparent glass container. Analysis of this precipitate using Fourier transform infrared spectroscopy and gas chromatography (with a flame ionization detector) confirmed that the precipitate was 99.99% pure cyclohexanone oxime (solid phase). In other words, even from a substrate processing solution containing submerged particles, high-purity cyclohexanone oxime (solid phase) can be obtained by utilizing recrystallization. Furthermore, by dissolving the precipitated cyclohexanone oxime (solid phase) in a solvent (IPA) and adding an auxiliary (NH4OH), a high-purity substrate processing solution (supersaturated solution of cyclohexanone oxime) without any submerged particles can be purified.

[0071] Therefore, in this embodiment, a refining apparatus 500 shown in Fig. 6 is incorporated into the substrate processing apparatus 1. Below, the configuration of the refining apparatus 500 will be described with reference to Fig. 6, and then the operation of the refining apparatus 500 will be described with reference to Fig. 8 and Fig. 9A to Fig. 9E.

[0072] As shown in FIG. 6 , the refining apparatus 500 has two ultrasonic tanks 510 and 520. The ultrasonic tank 510 has a tank 511 capable of storing a substrate processing solution, and an ultrasonic wave applying unit 512 attached to the tank 511. The operation of the ultrasonic wave applying unit 512 is controlled in response to a command from the control unit 4. When the ultrasonic wave applying unit 512 is activated in response to an operation command from the control unit 4 while the substrate processing solution containing cyclohexanone oxime particles in a metastable state is stored in the ultrasonic tank 510, ultrasonic vibrations are applied to the substrate processing solution stored in the tank 511, and the metastable state is maintained. On the other hand, when the ultrasonic wave applying unit 512 is stopped in response to an operation stop command from the control unit 4, recrystallization of the cyclohexanone oxime particles progresses in the ultrasonic tank 510, and high-purity cyclohexanone oxime (solid phase) is precipitated in the tank 511. Like the ultrasonic bath 510, the ultrasonic bath 520 also has a bath 521 capable of storing a substrate processing liquid and an ultrasonic wave applying unit 522 attached to the bath 521, and performs the same functions.

[0073] The ultrasonic tanks 510 and 520 are interconnected by a connecting pipe 530. One end of the connecting pipe 530 is connected to the bottom of the ultrasonic tank 510, and the other end is connected to the bottom of the ultrasonic tank 510. A pump 531 is installed in the center of the connecting pipe 530. A three-way valve 532 is installed between one end of the connecting pipe 530 and the installation position of the pump 531, and a three-way valve 533 is installed between the other end of the connecting pipe 530 and the installation position. Therefore, when the pump 531 operates in response to a command from the control unit 4 and the three-way valves 532 and 533 are switched to the liquid delivery position (see FIG. 9C ) in response to a command from the control unit 4, the substrate processing liquid is delivered between the ultrasonic tanks 510 and 520. The three-way valves 532 and 533 have a third port for draining the liquid from the ultrasonic tank 510, in addition to first and second ports for controlling the delivery of the substrate processing liquid. Therefore, when three-way valve 533 closes all ports and the first and third ports of three-way valve 532 open in response to a command from control unit 4, liquid can be drained from ultrasonic tank 510 via piping 534 (see FIG. 9D). Also, when three-way valve 532 closes all ports and the first and third ports of three-way valve 533 open in response to a command from control unit 4, liquid can be drained from ultrasonic tank 520 via piping 535.

[0074] Pipes 513 to 515 are connected to the ultrasonic bath 510. Pipe 515 is connected to a supply source of cyclohexanone oxime. Therefore, cyclohexanone oxime is replenished from the supply source to the ultrasonic bath 510 in response to a replenishment command from control unit 4. Note that what is supplied from the supply source may be cyclohexanone oxime (solid phase) or a relatively high concentration cyclohexanone oxime solution dissolved in the same solvent as the solvent component in the substrate processing solution.

[0075] The pipe 514 is connected to a supply source of the solvent (IPA in this embodiment) of the substrate processing liquid. Therefore, IPA is supplied from the supply source to the ultrasonic bath 510 in response to a supply command from the control unit 4.

[0076] The pipe 513 is connected to a supply source of an auxiliary agent (ammonia water in this embodiment) for the substrate processing liquid. Therefore, ammonia water is supplied from the supply source to the ultrasonic bath 510 in response to a supply command from the control unit 4.

[0077] Furthermore, a branch pipe 822 of the recovery pipe 821 extending from the second cup 82 is extended to the ultrasonic tank 510, and guides the used substrate processing liquid recovered in the second cup 82 to the ultrasonic tank 510. A valve 516 is provided in this branch pipe 822, and is controlled to open and close in response to an open / close command from the control unit 4. That is, when the valve 516 is opened, the recovered substrate processing liquid is sent to the ultrasonic tank 510 (recovery process). Conversely, when the valve 516 is closed, the sending of the recovered substrate processing liquid to the ultrasonic tank 510 is stopped.

[0078] Furthermore, in order to measure the concentration of cyclohexanone oxime in the ultrasonic bath 510, a concentration meter 541 is provided in the ultrasonic bath 510.

[0079] In this way, cyclohexanone oxime, IPA, NH4OH, and used substrate processing solution can be independently supplied to the ultrasonic tank 510. Therefore, when the concentration meter 541 detects that the cyclohexanone oxime concentration in the substrate processing solution stored in the ultrasonic tank 510 is low, the control unit 4 supplies cyclohexanone oxime to raise the concentration above the saturated concentration. The cyclohexanone oxime concentration can be adjusted by adding IPA to the substrate processing solution stored in the ultrasonic tank 510. Furthermore, NH4OH can be added to a substrate processing solution containing cyclohexanone oxime at a concentration exceeding the saturated concentration, thereby adjusting the cyclohexanone oxime particles to a metastable state. Furthermore, as described below, by supplying IPA while leaving only the cyclohexanone oxime (solid phase) precipitated in the ultrasonic tank 510, it is possible to thinly peel off the surface layer of the precipitate (cyclohexanone oxime (solid phase)) and remove impurities adhering to the precipitate. As a result, only high-purity cyclohexanone oxime (solid phase) remains in the ultrasonic tank 510, and by supplying appropriate amounts of IPA and NH4OH, a substrate processing solution containing high-purity, metastable cyclohexanone oxime particles can be obtained (purification process).

[0080] In order to send the thus-purified substrate processing liquid to the storage tank 401, a pipe 517 is provided connecting the bottom of the ultrasonic tank 510 to the pipe 403. A pump 518 and a valve 519 are interposed in the pipe 517. Therefore, the purified substrate processing liquid is sent to the storage tank 401 via the pipe 517 by operating the pump 518 in response to an operation command from the control unit 4 while the valve 519 is opened in response to an open command from the control unit 4. In this manner, the substrate processing liquid is replenished. In this manner, the ultrasonic tank 510 can alternately perform the recovery / purification process and the replenishment process.

[0081] Similarly to ultrasonic tank 510, pipes 523 to 525 are connected to the other ultrasonic tank 520. Based on the measurement results of concentration meter 542, cyclohexanone oxime can be replenished via pipe 525, IPA (solvent) can be supplied via pipe 524, and ammonia water (auxiliary) can be replenished via pipe 523. A branch pipe 823 of recovery pipe 821 extending from second cup 82 is connected to ultrasonic tank 520. Opening valve 526 on branch pipe 823 transfers the recovered substrate processing liquid to ultrasonic tank 520. Conversely, closing valve 527 stops the transfer of the recovered substrate processing liquid to ultrasonic tank 520. Therefore, similar to ultrasonic tank 510, recovery / purification and replenishment can be alternately performed in ultrasonic tank 520.

[0082] Fig. 8 is a flowchart showing the operation of the refining device shown in Fig. 6. Fig. 9A to Fig. 9E are diagrams each schematically showing an example of the operation of the refining device shown in Fig. 6. In these drawings, the symbols ON and OFF indicate the operation / non-operation of ultrasound application units 521 and 522, and in the symbols showing valves and three-way valves, those with black triangles indicate that the ports and valves are open, and those with white triangles indicate that the ports and valves are closed. Furthermore, the thick lines indicate the flow of liquid.

[0083] Each part of the refining apparatus 500 operates in accordance with a refining program pre-stored in the control unit 4 in parallel with the substrate processing in the substrate processing apparatus 1 shown in Fig. 6, as follows. As a result, while a recovery / refining process is performed in one of the ultrasonic baths 510, 520, a replenishment process is performed in the other. Note that in this embodiment, the refining apparatus 500 is controlled by the control unit 4 that controls the entire substrate processing apparatus 1. However, a dedicated control unit for controlling the refining apparatus 500 may be provided, and each part of the refining apparatus 500 may be controlled by the control unit.

[0084] In step S11, the control unit 4 sets the functions of the ultrasonic tanks 510 and 520 so that they can alternately switch between the ultrasonic tank performing the recovery and purification process and the ultrasonic tank performing the replenishment process. Here, it is assumed that the control unit 4 sets the ultrasonic tanks 510 and 520 to perform the recovery and purification process and the replenishment process, respectively, in step S11. At this point, the valves 516 and 526 are closed, and the supply of the substrate processing liquid recovered in the second cup 82 to the purification device 500 is stopped. Furthermore, all ports of the three-way valves 532 and 533 are closed, thereby restricting the flow of the substrate processing liquid before purification (hereinafter referred to as the "pre-purification processing liquid") between the ultrasonic tanks 510 and 520. Furthermore, both the ultrasonic wave applying units 522 and 523 are operating. The ultrasonic tank 510 stores the pre-purification processing liquid, while the ultrasonic tank 520 stores the purified substrate processing liquid.

[0085] In ultrasonic tank 520 where the replenishment process is performed, valve 529 is opened and pump 528 is operated, as shown in FIG. 9A. This causes the refined substrate processing liquid to be sent via pipe 527 to storage tank 401 (FIG. 6) of processing liquid supply unit 400 (step S12). As the substrate processing liquid is sent, the amount of substrate processing liquid stored in ultrasonic tank 520 gradually decreases and becomes empty ("YES" in step S13). Then, pump 528 stops and valve 529 closes (step S14). This completes the replenishment process.

[0086] In parallel with the replenishment process, recovery and purification processes are performed in the ultrasonic tank 510 (steps S15 to S19). In step S15, as shown in Fig. 9A, the valve 516 is opened, and the substrate processing liquid recovered in the second cup 82 is recovered into the ultrasonic tank 510, which functions as an ultrasonic purification tank, via pipes 821 and 822, and mixed with the pre-purification processing liquid already stored therein. When this process is completed, the valve 516 is closed.

[0087] If the measurement results from concentration meter 541 show that the concentration of cyclohexanone oxime particles contained in the purification pretreatment liquid is below the saturated concentration, i.e., if the purification pretreatment liquid is not supersaturated ("NO" in step S16), cyclohexanone oxime, IPA, or NH4OH is supplied to ultrasonic bath 510, the concentration of cyclohexanone oxime particles in the purification pretreatment liquid is adjusted (step S17), and then the process returns to step S16.

[0088] On the other hand, if it is confirmed that the concentration of cyclohexanone oxime particles exceeds the saturation concentration and that a supersaturated purification pretreatment solution exists in the ultrasonic bath 510 ("YES" in step S16), the ultrasonic wave application unit 512 stops and stops applying ultrasonic vibrations to the purification pretreatment solution (step S18), as shown in FIG. 9B. This initiates recrystallization of the metastable cyclohexanone oxime particles, and cyclohexanone oxime (solid phase) OX precipitates in the ultrasonic bath 510. When it is confirmed that the recrystallization is complete based on the measurement results of the concentration meter 541 and that the replenishment process is also complete, the first and second ports of the three-way valves 532 and 533 open, and the pump 531 is operated to empty the purification pretreatment solution stored in the ultrasonic bath 510 into the ultrasonic bath 520 via the piping 530, as shown in FIG. 9C. That is, the pre-purification solution is sent from the ultrasonic purification tank 510 to the empty ultrasonic purification tank 520 (step S19), and the ultrasonic purification tank 520 receives the pre-purification solution from the ultrasonic purification tank 510 (step S20). As a result, only the precipitate (cyclohexanone oxime (solid phase)) remains in the ultrasonic purification tank 510, while the ultrasonic purification tank 520 stores the pre-purification solution containing cyclohexanone oxime particles at a concentration below the saturation point, resulting in a state similar to that of the ultrasonic purification tank 510 before the start of the recovery and purification process.

[0089] When the transfer of the purification pretreatment liquid is completed, the pump 531 is stopped. Furthermore, the first and second ports of the three-way valves 532 and 533 are closed. Then, as shown in FIG. 9D, only IPA is supplied to the ultrasonic bath 510. This thinly peels off the surface layer of the precipitate, and impurities adhering to the precipitate are removed, i.e., the cyclohexanone oxime (solid phase) OX is washed. After this washing, the first and third ports of the three-way valve 532 are opened, and the washed IPA is discharged from the ultrasonic bath 510 along with the impurities through the drainage path formed by the pipe 530, the three-way valve 532, and the pipe 534. By repeating this washing of the precipitate, high-purity cyclohexanone oxime (solid phase) OX is obtained (step S21). Subsequently, as shown in FIG. 9E, IPA and NH4OH are supplied to the ultrasonic bath 510, and the operation of the ultrasonic wave applying unit 512 is resumed. As a result, the supersaturated substrate processing liquid is purified and stored in the ultrasonic bath 510 as a substrate processing liquid suitable for sublimation drying, similar to the ultrasonic bath 520 before the above-described replenishment process was performed (step S22).

[0090] When the replenishment process and the recovery and purification process are completed in this way, the process returns to step S11 and the replenishment process and the recovery and purification process are repeated. That is, the replenishment process, the recovery and purification process, and the replenishment process are performed in the ultrasonic baths 510 and 520, respectively.

[0091] As described above, the refining apparatus 500 refines the substrate processing solution using cyclohexanone oxime (solid phase) OX obtained by recrystallizing metastable cyclohexanone oxime particles. Therefore, the substrate processing solution obtained is free of impurities and submerged particles. Furthermore, by performing sublimation drying using this substrate processing solution, collapse of the pattern PT can be further suppressed.

[0092] <Batch-type substrate processing system> The application of the present invention is not limited to single-wafer substrate processing apparatuses, but can also be applied to substrate processing apparatuses installed in so-called batch-type substrate processing systems.

[0093] 10 is a diagram showing the configuration of a substrate processing system equipped with a second embodiment of the substrate processing apparatus according to the present invention. The substrate processing system 200 is a batch-type substrate processing system that processes a plurality of substrates W at once. The substrate processing system 200 includes a chemical liquid storage tank 210 that stores a chemical liquid, a rinse liquid storage tank 220 that stores a rinse liquid (e.g., water), a sublimation agent storage tank 230 that stores the substrate processing liquid for sublimation drying used in the first embodiment, and a supply liquid storage tank 240 that stores a supply liquid (e.g., a water-containing liquid). The sublimation agent storage tank 230 is connected to a pipe 405 extending from the processing liquid supply unit 400. The substrate processing liquid recovered by an overflow tank provided in the sublimation agent storage tank 230 is recovered in a purification device 500 via a pipe 821. The recovery and purification process is performed in this purification device 500. The refined substrate processing liquid is then returned to the sublimation agent storage tank 230 via the processing liquid supply unit 400. Furthermore, although not shown in Fig. 10, an ultrasonic generator as described in, for example, JP 2021-034442 A is provided below the sublimation agent storage tank 230, and it is possible to switch between applying and stopping ultrasonic waves to the substrate processing liquid in the sublimation agent storage tank 230.

[0094] The substrate processing system 200 further includes a lifter 250 that immerses the substrates W in the supply liquid stored in the supply liquid storage tank 240, and a lifter lifting unit 260 that raises and lowers the lifter 250. The lifter 250 supports each of the plurality of substrates W in a vertical position. The lifter lifting unit 260 raises and lowers the lifter 250 between a processing position (position indicated by a solid line in FIG. 10) where the substrates W held by the lifter 250 are located in the supply liquid storage tank 240, and a retracted position (position indicated by a two-dot chain line in FIG. 10) where the substrates W held by the lifter 250 are retracted upward from the supply liquid storage tank 240.

[0095] In a series of processes in the substrate processing system 200, a plurality of substrates W carried into a processing unit of the substrate processing system 200 are immersed in a chemical stored in a chemical storage tank 210. As a result, a chemical process (cleaning process or etching process) is performed on each substrate W (chemical process). After a predetermined period has elapsed since the start of immersion in the chemical storage tank 210, the plurality of substrates W are pulled out of the chemical storage tank 210 and transferred to the rinse liquid storage tank 220. Next, the plurality of substrates W are immersed in a rinse liquid stored in the rinse liquid storage tank 220. As a result, a rinse process is performed on the substrates W (rinsing process). After a predetermined period has elapsed since the start of immersion in the rinse liquid, the plurality of substrates W are pulled out of the rinse liquid storage tank 220 and transferred to the sublimation agent storage tank 230. Next, the plurality of substrates W are immersed in the substrate processing liquid stored in the sublimation agent storage tank 230. After a predetermined period of time has elapsed since the start of immersion in the substrate processing liquid, the plurality of substrates W are pulled up from the sublimation agent storage tank 230. During this pulling up, cyclohexanone oxime particles in the substrate processing liquid precipitate, and a solidified film begins to form on the surface of each substrate W. Then, the substrates W with the solidified film are transferred to the supply liquid storage tank 240.

[0096] A solidified film of the substrate processing liquid is formed over the entire surface of each substrate W transferred to the supply liquid storage tank 240. Then, the lifter lifting / lowering unit 260 is controlled to move the lifter 250 from the retracted position to the processing position, thereby immersing the multiple substrates W held by the lifter 250 in the supply liquid.

[0097] When a predetermined period of time has elapsed since the substrates W began to be immersed in the supply liquid, the lifter lifting unit 260 is controlled to move the lifter 250 from the processing position to the retracted position, thereby lifting the substrates W immersed in the supply liquid out of the supply liquid.

[0098] When the substrate W is pulled up from the supply liquid, a pull-up drying process (supply liquid removal process) is carried out. The pull-up drying process is carried out by blowing gas (for example, an inert gas such as nitrogen gas) onto the surface of the substrate W pulled up from the supply liquid storage tank 240 and pulling up the substrate W at a relatively slow speed (for example, several mm / sec). This removes the supply liquid from the entire surface of the substrate W.

[0099] The solidified film, i.e., cyclohexanone oxime (solid phase), then sublimes into a gas, which allows the solidified film to be removed from the surface of the substrate W without passing through a liquid state, thereby drying the surface of the substrate W while effectively suppressing or preventing pattern collapse.

[0100] 8 corresponds to an example of the "first step" of the present invention, step S18 corresponds to an example of the "second step" of the present invention, steps S21 and S22 correspond to an example of the "third step" of the present invention, and step S12 corresponds to an example of the "fourth step" of the present invention. Also, storage tank 401 corresponds to an example of the "storage unit" of the present invention.

[0101] The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described embodiment without departing from the spirit of the present invention. For example, in the above-described embodiment, the recovered substrate processing liquid is mixed and then used in the purification device 500, but the mixing is not essential and is optional. However, the mixing is beneficial in terms of reducing running costs, etc.

[0102] In the above embodiment, the precipitated cyclohexanone oxime OX is subjected to a washing treatment, but this may be omitted.

[0103] In the above embodiment, the pre-purification treatment liquid moves back and forth between the ultrasonic baths 510 and 520, and as the number of reciprocating movements increases, the amount of impurities and particles in the pre-purification treatment liquid increases. Therefore, the pre-purification treatment liquid may be configured to be drained through the pipes 534 and 535 when the number of reciprocating movements reaches a certain value.

[0104] In the above embodiment, the substrate processing liquid used is purified by the purification device 500, but it is not essential to perform the purification process. For example, a supersaturated solution of a sublimable substance may be used as the substrate processing liquid, which is obtained by adding an auxiliary agent when dissolving a sublimable substance (solid phase) in a solvent, thereby uniformly dispersing particles of the sublimable substance in the solution in excess of the solubility. [Industrial Applicability]

[0105] The present invention is applicable to all substrate processing liquids used to remove liquids adhering to substrates by utilizing the sublimation phenomenon of sublimable substances, as well as to all substrate processing techniques in which such substrate processing liquids are used to remove such liquids from substrates. [Explanation of symbols]

[0106] 1...Substrate processing equipment 4...Control unit 53...Nozzle 64...Processing liquid supply unit 230...Sublimation agent reservoir 400... Processing liquid supply unit 401...Storage tank (storage section) 402, 512, 522, 523...Ultrasonic wave application unit 500…Refining equipment 510, 520...Ultrasonic bath L...Substrate processing solution LF…Liquid film PT...pattern SF…solidified film W...Substrate Wf...(substrate) surface

Claims

1. 1. A substrate processing liquid for use in removing a liquid on a substrate having a patterned surface, comprising: a sublimable material; a solvent that dissolves the sublimable substance; an auxiliary agent that is added to a solution in which the sublimable substance is dissolved in the solvent to disperse particles of the sublimable substance that exceed the solubility in the solution, thereby increasing the concentration of the particles of the sublimable substance above a saturated concentration; A substrate processing solution comprising:

2. The substrate processing solution according to claim 1 , The substrate processing solution, wherein the auxiliary is a crystallization inhibitor that inhibits the sublimable substance in the solution from crystallizing.

3. 3. The substrate processing solution according to claim 1, the sublimable substance is cyclohexanone oxime; The auxiliary agent is a substrate processing solution that adjusts the pH of the solution so that the zeta potential of the sublimable substance in the solution becomes negative.

4. The substrate processing solution according to claim 3, The substrate processing solution, wherein the auxiliary agent is aqueous ammonia.

5. a processing solution preparation step of preparing the substrate processing solution according to claim 1; a liquid film forming step of supplying the substrate processing liquid prepared in the processing liquid preparing step onto a surface of a substrate on which a pattern has been formed, to form a liquid film of the substrate processing liquid on the surface of the substrate; a solidified film forming step of solidifying the liquid film of the substrate processing liquid to form a solidified film of the sublimable substance; a sublimation step of sublimating the solidified film and removing it from the surface of the substrate; A substrate processing method comprising:

6. 6. The substrate processing method according to claim 5, The substrate processing method, wherein the processing liquid preparation step includes a step of storing the substrate processing liquid in a storage tank to which ultrasonic vibrations are applied.

7. 7. The substrate processing method according to claim 6, The treatment liquid preparation step includes: a first step of preparing a supersaturated solution of the sublimable substance; a second step of precipitating the sublimable substance from the supersaturated solution; a third step of refining the substrate processing solution by adding the auxiliary to a solution obtained by dissolving the precipitated sublimable substance in the solvent; a fourth step of replenishing the substrate processing solution purified in the third step to the storage tank; A substrate processing method comprising:

8. 8. The substrate processing method according to claim 7, The substrate processing method, wherein the third step includes a step of washing the deposited sublimable substance before dissolving the deposited sublimable substance with the solvent.

9. 9. The substrate processing method according to claim 7 or 8, The first step is carried out in an ultrasonic bath to which ultrasonic vibrations are applied, the second step is carried out by stopping the application of ultrasonic waves to the ultrasonic bath in which the supersaturated solution is stored, The third step is performed by restarting application of ultrasonic vibration to the ultrasonic bath.

10. 10. The substrate processing method according to claim 6, further comprising: The liquid film forming step includes a step of supplying the substrate processing liquid onto the surface of the substrate by discharging the substrate processing liquid from a nozzle onto the surface of the substrate while applying ultrasonic vibrations to the substrate processing liquid within the nozzle.

11. 11. The substrate processing method according to claim 10, The liquid film forming step includes a step of delivering the substrate processing liquid from the storage tank to the nozzle while applying ultrasonic vibrations to the substrate processing liquid.

12. a reservoir for storing the substrate processing liquid according to claim 1; a processing liquid supply unit that supplies the substrate processing liquid stored in the storage unit to a surface of a substrate on which a pattern is formed; A substrate processing apparatus comprising:

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