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

Abstract

To provide a substrate processing method, a substrate processing apparatus, and a substrate processing solution capable of performing sublimation drying while further preventing collapse of pattern formed on the surface of a substrate.SOLUTION: A substrate processing method according to the present invention is a substrate processing method for processing a pattern-formed surface of a substrate W, and includes a supplying step of supplying a substrate processing liquid containing a sublimable substance and a solvent to the pattern-formed surface, a solidifying step of evaporating the solvent in a liquid film of the substrate processing liquid supplied to the pattern-formed surface in the supplying step to precipitate the sublimable substance and form a solidified film containing the sublimable substance; and a sublimation step of sublimating the solidified film to remove the solidified film, wherein the sublimable substance contains methyl 5-bromo-2-furancarboxylate.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a substrate processing method, a substrate processing apparatus, and a substrate processing solution for removing liquid adhering to various substrates (hereinafter referred to as "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. [Background technology]

[0002] In recent years, with the miniaturization of patterns formed on substrates such as semiconductor substrates, the aspect ratio (the ratio of height to width of the convex portion of the pattern) of the convex portion of the uneven pattern has been increasing. As a result, during the drying process, the surface tension acting on the interface between a liquid such as a cleaning liquid or a rinse liquid that has entered the concave portion of the pattern and a gas in contact with the liquid attracts adjacent convex portions in the pattern and causes them to collapse, which is a problem known as pattern collapse.

[0003] As a drying technique aimed at preventing such pattern collapse, for example, Patent Document 1 discloses a substrate drying method for removing a liquid on a substrate having a concave-convex pattern formed on its surface and drying the substrate. This substrate drying method involves supplying a solution of a sublimable substance to the substrate, filling the recesses of the pattern with the solution, drying the solvent in the solution to fill the recesses of the pattern with the sublimable substance in a solid state, and heating the substrate to a temperature higher than the sublimation temperature of the sublimable substance to remove the sublimable substance from the substrate. Patent Document 1 claims that this method prevents pattern collapse by suppressing stress acting on the convex portions of the pattern that may arise due to the surface tension of the liquid on the substrate and collapsing the convex portions of the pattern.

[0004] Furthermore, Patent Document 2 discloses a substrate processing method that uses a substrate processing solution containing at least one sublimable substance selected from camphor and naphthalene and a solvent such as isopropyl alcohol to perform sublimation drying of the surface of a substrate on which a fine pattern has been formed. This substrate processing method is said to be able to effectively prevent partial or localized pattern collapse compared to conventional substrate processing solutions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-243869 [Patent Document 2] Japanese Patent Application Publication No. 2020-4948 Summary of the Invention [Problem to be solved by the invention]

[0006] However, even if the above-mentioned sublimation drying method is used, there is a problem that if the mechanical strength of the pattern is extremely low, the collapse of the pattern cannot be sufficiently prevented.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a substrate processing method, a substrate processing apparatus, and a substrate processing solution that are capable of performing sublimation drying while further preventing collapse of a pattern formed on the surface of a substrate. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, a substrate processing method according to the present invention is a substrate processing method for processing a pattern-formed surface of a substrate, comprising: a supplying step of supplying a substrate processing liquid containing a sublimable substance and a solvent onto the pattern-formed surface; a solidifying step of evaporating the solvent in a liquid film of the substrate processing liquid supplied onto the pattern-formed surface in the supplying step to precipitate the sublimable substance and form a solidified film containing the sublimable substance; and a sublimation step of sublimating the solidified film to remove the solidified film, wherein the sublimable substance contains methyl 5-bromo-2-furancarboxylate.

[0009] According to the substrate processing method having the above configuration, for example, when a liquid is present on the pattern-formed surface of a substrate, the liquid can be removed while preventing collapse of the pattern by the principle of sublimation drying. Specifically, after a substrate processing liquid is supplied to the pattern-formed surface in a supplying step, a sublimable substance is precipitated by evaporating the solvent in the liquid film of the substrate processing liquid in a solidifying step to form a solidified film. The solidified film is then removed by sublimation. Here, in the above configuration, the sublimable substance contained in the substrate processing liquid is one containing methyl 5-bromo-2-furancarboxylate. This allows sublimation drying to be performed while effectively preventing collapse of the pattern, even in the case of a pattern with extremely low mechanical strength, compared to substrate processing liquids using conventional sublimable substances.

[0010] In the above configuration, it is preferable that the method further includes a thinning step of thinning the liquid film of the substrate processing liquid supplied in the supply step onto the pattern formation surface by rotating the substrate at a first rotation speed around a rotation axis parallel to the vertical direction of the pattern formation surface, and the solidification step is a step of rotating the substrate around the rotation axis at a second rotation speed faster than the first rotation speed to evaporate the solvent in the liquid film.

[0011] In the above-described configuration, the solidifying step may promote the formation of the solidified film by supplying an inert gas to the pattern formation surface after the sublimable substance is deposited.

[0012] Furthermore, in the above-described configuration, it is preferable that the content of the sublimable substance is in the range of 3.1 vol% or more and 6.3 vol% or less with respect to the total volume of the substrate processing solution. By setting the content of the sublimable substance to 3.1 vol% or more, pattern collapse can be more effectively suppressed even for substrates having fine patterns with large aspect ratios. On the other hand, by setting the content of the sublimable substance to 6.3 vol% or less, the thickness of the solidified film can be suppressed from becoming excessively large, and the rate of pattern collapse can be prevented from becoming too high.

[0013] In the above-mentioned configuration, it is preferable to use a solvent having a vapor pressure at room temperature greater than that of the sublimable substance, which facilitates precipitation of methyl 5-bromo-2-furancarboxylate by evaporation of the solvent and allows for satisfactory formation of a solidified film containing the sublimable substance.

[0014] Furthermore, in the above-mentioned configuration, it is preferable that the solvent is at least one of methanol, butanol, isopropyl alcohol, and acetone.

[0015] In order to solve the above-mentioned problems, the present invention also provides a substrate processing apparatus for processing a pattern-formed surface of a substrate, comprising: a substrate holding unit that holds the substrate rotatably about a rotation axis parallel to a direction perpendicular to the pattern-formed surface; a supply unit that supplies a substrate processing liquid containing a sublimable substance and a solvent to the pattern-formed surface of the substrate held by the substrate holding unit; and a sublimation unit that sublimes a solidified film containing the sublimable substance and removes the solidified film, wherein the substrate holding unit rotates the substrate about the rotation axis to evaporate the solvent in the liquid film of the substrate processing liquid supplied to the pattern-formed surface by the supply unit, thereby precipitating the sublimable substance and forming a solidified film containing the sublimable substance, and the sublimable substance in the substrate processing liquid supplied by the supply unit comprises methyl 5-bromo-2-furancarboxylate.

[0016] The substrate processing apparatus having the above configuration, for example, when a liquid is present on the pattern-formed surface of a substrate, can remove the liquid while preventing collapse of the pattern by utilizing the principle of sublimation drying. Specifically, the substrate holder holds the substrate so that it can rotate about a rotation axis parallel to the perpendicular direction of the pattern-formed surface. The supply unit supplies the substrate processing liquid to the pattern-formed surface of the substrate held by the substrate holder. The substrate holder rotates the substrate to evaporate the solvent from the liquid film of the substrate processing liquid. This allows the sublimable substance to precipitate and form a solidified film. The sublimation unit then sublimates the solidified film containing the sublimable substance, thereby removing the solidified film. In the above configuration, the sublimable substance contained in the substrate processing liquid is methyl 5-bromo-2-furancarboxylate. This allows sublimation drying to be performed while effectively preventing collapse of the pattern, even for patterns with extremely low mechanical strength, compared to substrate processing liquids using conventional sublimable substances.

[0017] In the above configuration, it is preferable that the substrate holding unit thins the liquid film of the substrate processing liquid supplied to the pattern formation surface by the supply unit by rotating the substrate around the rotation axis at a first rotation speed, and evaporates the solvent in the liquid film by rotating the substrate around the rotation axis at a second rotation speed that is faster than the first rotation speed when thinning the liquid film of the substrate processing liquid.

[0018] In the above configuration, the sublimation section is a gas supply section that supplies an inert gas toward the pattern formation surface, and the gas supply section may also promote the formation of the solidified film by supplying the inert gas toward the pattern formation surface after deposition of the sublimable substance during the formation of the solidified film.

[0019] Furthermore, in the above-described configuration, it is preferable that the content of the sublimable substance is in the range of 3.1 vol% or more and 6.3 vol% or less with respect to the total volume of the substrate processing solution. By setting the content of the sublimable substance to 3.1 vol% or more, pattern collapse can be more effectively suppressed even for substrates having fine patterns with large aspect ratios. On the other hand, by setting the content of the sublimable substance to 6.3 vol% or less, the thickness of the solidified film can be suppressed from becoming excessively large, and the rate of pattern collapse can be prevented from becoming too high.

[0020] In the above-described configuration, it is preferable to use a solvent having a vapor pressure at room temperature greater than that of the sublimable substance, which facilitates precipitation of methyl 5-bromo-2-furancarboxylate by evaporation of the solvent and allows for satisfactory formation of a solidified film containing the sublimable substance.

[0021] Furthermore, in the above-mentioned configuration, it is preferable that the solvent is at least one of methanol, butanol, isopropyl alcohol, and acetone.

[0022] In order to solve the above-mentioned problems, the present invention also provides a substrate processing liquid used to remove a liquid on a substrate having a pattern-formed surface, the substrate processing liquid comprising a sublimable substance and a solvent, wherein the sublimable substance comprises methyl 5-bromo-2-furancarboxylate.

[0023] According to the above-described configuration, by including methyl 5-bromo-2-furancarboxylate as a sublimable substance in the substrate processing solution, it is possible to perform sublimation drying while effectively suppressing pattern collapse, even in the case of a pattern having extremely low mechanical strength, as compared with substrate processing solutions using conventional sublimable substances.

[0024] Furthermore, in the above-described configuration, it is preferable that the content of the sublimable substance is in the range of 3.1 vol% or more and 6.3 vol% or less with respect to the total volume of the substrate processing solution. By setting the content of the sublimable substance to 3.1 vol% or more, pattern collapse can be more effectively suppressed even for substrates having fine patterns with large aspect ratios. On the other hand, by setting the content of the sublimable substance to 6.3 vol% or less, the thickness of the solidified film can be suppressed from becoming excessively large, and the rate of pattern collapse can be prevented from becoming too high.

[0025] In the above-mentioned configuration, it is preferable that the solvent has a vapor pressure at room temperature greater than that of the sublimable substance, which facilitates precipitation of methyl 5-bromo-2-furancarboxylate by evaporation of the solvent and allows for successful formation of a solidified film containing the sublimable substance.

[0026] Furthermore, in the above-mentioned configuration, it is preferable that the solvent is at least one of methanol, butanol, isopropyl alcohol, and acetone. [Effects of the Invention]

[0027] According to the present invention, it is possible to provide a substrate processing method, a substrate processing apparatus, and a substrate processing solution that can suppress pattern collapse on the pattern-forming surface of a substrate, compared to conventional substrate processing solutions containing sublimable substances, and that can effectively suppress pattern collapse even for patterns with extremely low mechanical strength. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a plan view illustrating a schematic configuration of a substrate processing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory view illustrating an outline of a processing unit in the substrate processing apparatus. [Figure 3] FIG. 3(a) is a block diagram showing a schematic configuration of a substrate processing liquid storage unit, and FIG. 3(b) is an explanatory view showing a specific configuration of the substrate processing liquid storage unit. [Figure 4] FIG. 2 is a block diagram showing a schematic configuration of a gas storage unit in the substrate processing apparatus. [Figure 5] 10 is a flowchart illustrating a substrate processing method using the substrate processing apparatus according to the present embodiment. [Figure 6] FIG. 6(a) is a schematic diagram showing the state of the substrate W after the substrate processing liquid supply process is completed, and FIG. 6(b) is a schematic diagram showing the state of the substrate W after the thinning process is completed. [Figure 7] Figure 7(a) is a schematic diagram showing the state of the substrate W at the start of the solidification process, Figure 7(b) is a schematic diagram showing the state where a solidified film has been formed on the surface of the substrate, and Figure 7(c) is a schematic diagram showing the state where the solidified film has been removed by sublimation. [Figure 8] 10 is a graph showing an example of an image of a decrease in thickness of a liquid film (thin film) of a substrate processing liquid on a substrate W due to evaporation of a solvent. DETAILED DESCRIPTION OF THE INVENTION

[0029] An embodiment of the present invention will be described below. In this specification, the term "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, in this specification, the term "pattern-formed surface" refers to a surface of a substrate, regardless of whether it is flat, curved, or uneven, on which an uneven pattern is formed in any region. In this specification, the substrate is exemplified as having a circuit pattern or the like (hereinafter referred to as "pattern") formed on only one main surface. Here, the pattern-formed surface (main surface) on which the pattern is formed is referred to as the "front surface," and the opposite main surface on which the pattern is not formed is referred to as the "rear surface." Furthermore, the surface of the substrate facing downward is referred to as the "lower surface," and the surface of the substrate facing upward is referred to as the "upper surface." In this embodiment, the upper surface is referred to as the upper surface.

[0030] (Substrate processing liquid) First, the substrate processing liquid according to this embodiment will be described. The substrate processing liquid of this embodiment contains a sublimable substance and a solvent. The substrate processing liquid of this embodiment may consist only of a sublimable substance and a solvent. The substrate processing liquid of this embodiment functions to assist in a drying process for removing a liquid present on the pattern-formed surface of a substrate. In this specification, "sublimability" means that a single substance, compound, or mixture has the property of undergoing a phase transition from solid to gas or from gas to solid without passing through a liquid state, and "sublimable substance" means a substance having such sublimability.

[0031] The sublimable substance includes methyl 5-bromo-2-furancarboxylate, and may consist solely of methyl 5-bromo-2-furancarboxylate.

[0032] Methyl 5-bromo-2-furancarboxylate is represented by the following chemical formula: Methyl 5-bromo-2-furancarboxylate can function as a sublimable substance in the substrate processing solution of this embodiment.

[0033] [ka]

[0034] Methyl 5-bromo-2-furancarboxylate is preferably present in the substrate processing solution in a dissolved state in the solvent. In this specification, "dissolved state" means that 0.1 g or more of methyl 5-bromo-2-furancarboxylate is dissolved in 100 g of the solvent at 23°C, for example.

[0035] The content (concentration) of methyl 5-bromo-2-furancarboxylate can be appropriately set depending on, for example, the thickness of the solidified film of the substrate processing solution formed on the pattern-formed surface of the substrate. Specifically, the content of methyl 5-bromo-2-furancarboxylate is preferably 3.1 vol% or more and 6.3 vol% or less, more preferably 3.7 vol% or more and 6.0 vol% or less, and particularly preferably 4.2 vol% or more and 5.4 vol% or less, based on the total volume of the substrate processing solution. Specific examples of the content of methyl 5-bromo-2-furancarboxylate include 3.1, 3.5, 3.7, 4.0, 4.2, 4.3, 4.5, 4.7, 5.0, 5.3, 5.4, 5.5, 5.7, 6.0, and 6.3 vol%, and may be within a range between any two of the values ​​exemplified here. By setting the content of methyl 5-bromo-2-furancarboxylate to 3.1 vol% or more, pattern collapse can be more effectively suppressed even for substrates with fine patterns having a large aspect ratio.On the other hand, by setting the content of methyl 5-bromo-2-furancarboxylate to 6.3 vol% or less, the thickness of the solidified film can be suppressed from becoming excessively large, and the rate of pattern collapse can be prevented from becoming too high.

[0036] In this embodiment, the substrate processing solution may contain a known sublimable substance other than methyl 5-bromo-2-furancarboxylate within a range that does not impair the effects of the present invention. In this case, the content of the other sublimable substance can be appropriately set depending on the type of the other sublimable substance.

[0037] The solvent can function as a solvent that dissolves methyl 5-bromo-2-furancarboxylate. The solvent preferably has a vapor pressure at room temperature that is greater than the vapor pressure of methyl 5-bromo-2-furancarboxylate at room temperature. This facilitates evaporating the solvent to precipitate methyl 5-bromo-2-furancarboxylate. In this specification, "room temperature" refers to a temperature within the range of 5°C or higher and 35°C or lower, 10°C or higher and 30°C or lower, or 20°C or higher and 25°C or lower.

[0038] The solvent is preferably at least one of alcohols such as methanol, butanol, and isopropyl alcohol, and acetone. Of these solvents, isopropyl alcohol is preferred in this embodiment because the vapor pressure of isopropyl alcohol at room temperature is greater than the vapor pressure of methyl 5-bromo-2-furancarboxylate at room temperature.

[0039] The method for producing the substrate processing solution according to this embodiment is not particularly limited, and examples thereof include a method in which crystalline methyl 5-bromo-2-furancarboxylate is added to a solvent at room temperature and atmospheric pressure so as to achieve a certain content. Note that "atmospheric pressure" refers to an environment within the range of 0.7 to 1.3 atmospheres, with standard atmospheric pressure (1 atmosphere, 1013 hPa) as the center.

[0040] In the method for producing a substrate processing solution, crystalline methyl 5-bromo-2-furancarboxylate may be added to a solvent, followed by filtration. This reduces or prevents the generation of residues from the substrate processing solution on the pattern-formed surface of a substrate when the substrate processing solution is supplied to the pattern-formed surface and used to remove the liquid. The filtration method is not particularly limited, and for example, filter filtration can be used.

[0041] The substrate processing solution of this embodiment can be stored at room temperature. However, from the viewpoint of suppressing changes in the concentration of methyl 5-bromo-2-furancarboxylate due to evaporation of the solvent, it is preferable to store it at a low temperature (for example, about 20°C). Furthermore, in order to prevent evaporation of the solvent, it is more preferable to store the substrate processing solution in a sealed, dark place. When using the substrate processing solution stored at a low temperature, it is preferable to use it after allowing the temperature of the substrate processing solution to return to the operating temperature or room temperature, etc., from the viewpoint of preventing the inclusion of moisture due to condensation.

[0042] (Substrate processing equipment) <Overall configuration of substrate processing equipment> A substrate processing apparatus according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a plan view showing a schematic configuration of a substrate processing apparatus 100 according to this embodiment. The substrate processing apparatus 100 of this embodiment is a single-wafer type substrate processing apparatus used for cleaning processing (including rinsing processing) for removing contaminants such as particles adhering to a substrate, and for drying processing after the cleaning processing.

[0043] As shown in FIG. 1, the substrate processing apparatus 100 includes a substrate processing section 110 that performs various processes on substrates W, and an indexer section 120.

[0044] The indexer unit 120 has the function of supplying substrates W to the substrate processing unit 110 or retrieving substrates W from the substrate processing unit 110. Specifically, the indexer unit 120 has four container holders 121, each of which is provided with one container C. Examples of the container C include a FOUP (Front Opening Unified Pod), a SMIF (Standard Mechanical Interface) pod, and an OC (Open Cassette), which accommodate multiple substrates W in a sealed state. Note that, in this embodiment, an example will be described in which there are four container holders 121, but the present invention is not limited to this. There may be more than one container holder 121.

[0045] The indexer unit 120 further includes a first transport unit 122 for transporting substrates W. The first transport unit 122 is provided between the container holding unit 121 and the substrate processing unit 110. The first transport unit 122 includes a base unit 122a fixed to the apparatus housing, an articulated arm 122b rotatable about a vertical axis relative to the base unit 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 and held on its upper surface. The first transport unit 122 can access a container C held by the container holding unit 121 to remove an unprocessed substrate W from the container C or store a processed substrate W in the container C.

[0046] The substrate processing unit 110 performs cleaning processing (including rinsing processing) and drying processing after cleaning processing on substrates. The substrate processing unit 110 includes a second transport unit 111 located approximately in the center in a plan view, and four processing units 1 arranged to surround the second transport unit 111. For example, a substrate transport robot can be used as the second transport unit 111. The second transport unit 111 randomly accesses each processing unit 1 to hand over the substrate W. The substrate processing unit 110 includes multiple processing units 1, enabling parallel processing of multiple substrates W.

[0047] <Processing unit configuration> Next, the configuration of the processing unit 1 will be described with reference to FIGS. Fig. 2 is an explanatory diagram showing an outline of a substrate processing apparatus according to this embodiment. Fig. 3(a) is a block diagram showing a schematic configuration of a substrate processing liquid storage unit, and Fig. 3(b) is an explanatory diagram showing a specific configuration of the substrate processing liquid storage unit. Fig. 4 is a block diagram showing a schematic configuration of a gas storage unit. In Fig. 2, XYZ orthogonal coordinate axes are appropriately displayed to clarify the directional relationships of the objects shown. In Fig. 2, the XY plane represents the horizontal plane, and the +Z direction represents the vertical upward direction.

[0048] The processing unit 1 includes at least a chamber 11 which is a container for accommodating a substrate W, a substrate holding part 51 which holds the substrate W, a processing liquid supply part (supply part) 21 which supplies a substrate processing liquid to the substrate W held by the substrate holding part 51, an IPA supply part 31 which supplies IPA (isopropyl alcohol) to the substrate W held by the substrate holding part 51, a gas supply part 41 (sublimation part) which supplies gas to the substrate W held by the substrate holding part 51, a splash prevention cup 12 which collects IPA, substrate processing liquid, etc. which are supplied to the substrate W held by the substrate holding part 51 and discharged outside the peripheral edge of the substrate W, and a rotation drive part 14 which independently rotates the arms of each part of the processing unit 1, which will be described later.

[0049] The substrate holding unit 51 includes a rotation drive unit 52, a spin base 53, and chuck pins 54. The spin base 53 has a planar size slightly larger than the substrate W. A plurality of chuck pins 54 for gripping the peripheral edge of the substrate W are provided upright near the peripheral edge of the spin base 53. The number of chuck pins 54 to be provided is not particularly limited, but it is preferable to provide at least three or more in order to securely hold the circular substrate W. In this embodiment, three chuck pins 54 are arranged at equal intervals along the peripheral edge of the spin base 53. Each chuck pin 54 includes a substrate support pin that supports the peripheral edge of the substrate W from below, and a substrate holding pin that presses against the outer peripheral edge of the substrate W supported by the substrate support pin to hold the substrate W.

[0050] In this embodiment, the substrate W is held by the spin base 53 and the chuck pins 54, but the present invention is not limited to this substrate holding method. For example, the back surface Wb of the substrate W may be held by an adsorption method such as a spin chuck.

[0051] The spin base 53 is connected to a rotation drive unit 52. The rotation drive unit 52 rotates around an axis A1 along the Z direction in response to an operation command from the control unit 13. The rotation drive unit 52 is composed of a known belt, motor, and rotation shaft. When the rotation drive unit 52 rotates around the axis A1, the substrate W held by the chuck pins 54 above the spin base 53 rotates together with the spin base 53 around a rotation axis parallel to the vertical direction of the surface Wf of the substrate W, i.e., around the axis A1.

[0052] Next, the processing liquid supply unit (supply unit) 21 will be described. The processing liquid supply unit 21 is a unit that supplies a substrate processing liquid to the pattern formation surface of the substrate W. As shown in FIG. 2 , the processing liquid supply unit 21 includes at least a nozzle 22, an arm 23, a pivot shaft 24, a pipe 25, a valve 26, and a substrate processing liquid storage unit 27.

[0053] The nozzle 22 is attached to the tip of a horizontally extending arm 23 and is disposed above the spin base 53. The rear end of the arm 23 is supported rotatably about an axis J1 by a pivot shaft 24 extending in the Z direction, and the pivot shaft 24 is fixedly disposed within the chamber 11. The arm 23 is connected to a rotation drive unit 14 via the pivot shaft 24. The rotation drive unit 14 is electrically connected to the control unit 13 and rotates the arm 23 about the axis J1 in response to an operation command from the control unit 13. As the arm 23 rotates, the nozzle 22 also moves. Note that the nozzle 22 is normally disposed at a retracted position outside the peripheral edge of the substrate W and outside the splash prevention cup 12. When the arm 23 rotates in response to an operation command from the control unit 13, the nozzle 22 is disposed above the center of the surface Wf of the substrate W (at or near the axis A1).

[0054] The valve 26 is electrically connected to the control unit 13 and is normally closed. Opening and closing of the valve 26 is controlled by an operation command from the control unit 13. When the valve 26 is opened by an operation command from the control unit 13, the substrate processing liquid passes through the pipe 25 and is supplied from the nozzle 22 onto the surface Wf of the substrate W.

[0055] As shown in Figures 3(a) and 3(b), the substrate processing liquid storage unit 27 at least includes a substrate processing liquid storage tank 271, an agitation unit 277 that agitates the substrate processing liquid in the substrate processing liquid storage tank 271, a pressurization unit 274 that pressurizes the substrate processing liquid storage tank 271 to discharge the substrate processing liquid, and a temperature adjustment unit 272 that heats the substrate processing liquid in the substrate processing liquid storage tank 271.

[0056] The substrate processing liquid storage tank 271 includes a stock solution tank 281 that stores a stock solution of the substrate processing liquid, and a solvent tank 282 that stores a solvent. The stock solution tank 281 is connected to the substrate processing liquid storage tank 271 via a pipe 283, and a valve 284 is inserted in the pipe 283. The stock solution of the substrate processing liquid contains at least a sublimable substance and a solvent, and the concentration of the sublimable substance is higher than the concentration of the sublimable substance contained in the substrate processing liquid during use. The solvent tank 282 is connected to the substrate processing liquid storage tank 271 via a pipe 285, and a valve 286 is inserted in the pipe 285. The solvent stored in the solvent tank 282 is preferably the same type as the solvent contained in the stock solution of the substrate processing liquid. The valves 284 and 286 are electrically connected to the control unit 13 and are normally closed. The opening and closing of the valves 284 and 286 is controlled by operation commands from the control unit 13.

[0057] When valve 284 is opened in response to an operation command from control unit 13, the undiluted substrate processing liquid is pressure-fed from undiluted liquid tank 281 and supplied to substrate processing liquid storage tank 271 via pipe 283. When valve 286 is opened in response to an operation command from control unit 13, the solvent is pressure-fed from solvent tank 282 and supplied to substrate processing liquid storage tank 271 via pipe 285. As a result, the undiluted substrate processing liquid and the solvent are mixed in substrate processing liquid storage tank 271, and the undiluted substrate processing liquid is diluted, thereby preparing a substrate processing liquid containing a sublimable substance at a desired concentration. The concentration of the sublimable substance can be adjusted by adjusting the time and opening degree for which valves 284 and 286 are opened by control unit 13 (i.e., the flow rates of the undiluted substrate processing liquid and the solvent).

[0058] 3(b), the agitation unit 277 includes a rotation unit 279 that agitates the substrate processing liquid in the substrate processing liquid storage tank 271, and an agitation control unit 278 that controls the rotation of the rotation unit 279. The agitation control unit 278 is electrically connected to the control unit 13. The rotation unit 279 includes a propeller-shaped agitation blade at the tip of the rotation shaft (the lower end of the rotation unit 279 in FIG. 3(b)). The control unit 13 issues an operation command to the agitation control unit 278, causing the rotation unit 279 to rotate, thereby agitating the substrate processing liquid and homogenizing the concentration of the sublimable substance in the substrate processing liquid and the temperature of the substrate processing liquid.

[0059] Furthermore, the method for making the concentration and temperature of the substrate processing liquid in the substrate processing liquid storage tank 271 uniform is not limited to the method described above, and any known method can be used, such as a method of circulating the substrate processing liquid using a separate circulation pump.

[0060] The pressurizing unit 274 is composed of a nitrogen gas tank 275, which is a supply source of inert gas that pressurizes the inside of the substrate processing liquid storage tank 271, a pump 276 that pressurizes the nitrogen gas, and a pipe 273. The nitrogen gas tank 275 is connected to the substrate processing liquid storage tank 271 by the pipe 273, and the pump 276 is inserted into the pipe 273.

[0061] The temperature adjustment unit 272 is electrically connected to the control unit 13 and adjusts the temperature of the substrate processing liquid stored in the substrate processing liquid storage tank 271 by, for example, heating the substrate processing liquid in response to an operation command from the control unit 13. The temperature adjustment is performed, for example, so as to prevent sublimable substances dissolved in the substrate processing liquid from precipitating. The upper limit of the temperature adjustment is preferably a temperature lower than the boiling point of the solvent, such as IPA. This prevents evaporation of the solvent and prevents the substrate processing liquid with the desired composition from being unable to be supplied to the substrate W. The temperature adjustment unit 272 is not particularly limited, and any known temperature adjustment mechanism, such as a resistance heater, a Peltier element, or a pipe through which temperature-adjusted water flows, can be used.

[0062] 2, the IPA supply unit 31 is a unit that supplies IPA to the substrate W held by the substrate holder 51. The IPA supply unit 31 includes a nozzle 32, an arm 33, a pivot shaft 34, a pipe 35, a valve 36, and an IPA tank 37.

[0063] The nozzle 32 is attached to the tip of a horizontally extending arm 33 and is disposed above the spin base 53. The rear end of the arm 33 is supported rotatably about an axis J2 by ​​a pivot shaft 34 extending in the Z direction, and the pivot shaft 34 is fixedly disposed within the chamber 11. The arm 33 is connected to a rotation drive unit 14 via the pivot shaft 34. The rotation drive unit 14 is electrically connected to the control unit 13 and rotates the arm 33 about the axis J2 in response to an operation command from the control unit 13. The nozzle 32 also moves as the arm 33 rotates. The nozzle 32 is normally disposed at a retracted position outside the peripheral edge of the substrate W and outside the splash prevention cup 12. When the arm 33 rotates in response to an operation command from the control unit 13, the nozzle 32 is disposed above the center of the surface Wf of the substrate W (at or near the axis A1).

[0064] The valve 36 is electrically connected to the control unit 13 and is normally closed. Opening and closing of the valve 36 is controlled by an operation command from the control unit 13. When the valve 36 is opened by an operation command from the control unit 13, IPA is supplied from the nozzle 32 through the pipe 35 onto the front surface Wf of the substrate W.

[0065] The IPA tank 37 is connected to the nozzle 32 via a pipe 35, and a valve 36 is inserted midway along the route of the pipe 35. IPA is stored in the IPA tank 37, and the IPA in the IPA tank 37 is pressurized by a pump (not shown), and the IPA is sent from the pipe 35 toward the nozzle 32.

[0066] In this embodiment, IPA is used in the IPA supply unit 31, but the present invention is not limited to IPA and any liquid that is soluble in sublimable substances and deionized water (DIW) may be used. Alternatives to IPA in this embodiment include methanol, ethanol, acetone, benzene, carbon tetrachloride, chloroform, hexane, decalin, tetralin, acetic acid, cyclohexanol, ether, and hydrofluoroether.

[0067] As shown in FIG. 2, the gas supply unit 41 is a unit that supplies gas to the substrate W held by the substrate holder 51, and includes a nozzle 42, an arm 43, a support shaft 44, piping 45, a valve 46, a gas storage unit 47, a shielding plate 48, a lifting mechanism 49, and a shielding plate rotation mechanism (not shown).

[0068] 4, the gas storage section 47 includes a gas tank 471 that stores gas, and a gas temperature adjustment section 472 that adjusts the temperature of the gas stored in the gas tank 471. The gas temperature adjustment section 472 is electrically connected to the control unit 13, and adjusts the temperature by heating or cooling the gas stored in the gas tank 471 in response to an operation command from the control unit 13. The gas temperature adjustment section 472 is not particularly limited, and any known temperature adjustment mechanism can be used, such as a Peltier element or piping through which temperature-adjusted water flows.

[0069] 2, gas storage section 47 (more specifically, gas tank 471) is connected to nozzle 42 via piping 45, and a valve 46 is inserted midway along the path of piping 45. The gas in gas storage section 47 is pressurized by a pressurizing means (not shown) and sent to piping 45. Note that the pressurizing means can be realized by compressing and storing the gas in gas storage section 47, in addition to pressurizing with a pump or the like, and therefore any pressurizing means may be used.

[0070] Valve 46 is electrically connected to control unit 13 and is normally closed. Opening and closing of valve 46 is controlled by an operation command from control unit 13. When valve 46 is opened by an operation command from control unit 13, an inert gas such as nitrogen gas stored in gas tank 471 passes through pipe 45 and is discharged from nozzle 42.

[0071] The nozzle 42 is provided at the tip of a support shaft 44. The support shaft 44 is held at the tip of an arm 43 that extends horizontally. As a result, the nozzle 42 is disposed above the spin base 53, more specifically, above the center of the surface Wf of the substrate W (on or near the axis A1).

[0072] The arm 43 extends in a substantially horizontal direction, and its rear end is supported by a lifting mechanism 49. The arm 43 is also connected to the lifting drive unit 16 via the lifting mechanism 49. The lifting drive unit 16 is electrically connected to the control unit 13, and the lifting mechanism 49 is raised and lowered in the vertical direction in response to an operation command from the control unit 13, thereby lifting and lowering the arm 43 as a unit. This allows the nozzle 42 and the shielding plate 48 to approach or move away from the spin base 53. Specifically, the control unit 13 controls the operation of the lifting mechanism 49 to raise the nozzle 42 and the shielding plate 48 to a spaced position (position shown in FIG. 2) above the spin chuck 55 when the substrate W is loaded or unloaded from the processing unit 1, and to lower the nozzle 42 and the shielding plate 48 to a height position that establishes a set distance from the surface Wf of the substrate W when a sublimation process, described later, is performed. The lifting mechanism 49 is fixedly provided within the chamber 11.

[0073] Support shaft 44 has a hollow, generally cylindrical shape, and a gas supply pipe (not shown) is inserted therein. The gas supply pipe is connected to piping 45. This allows nitrogen gas stored in gas storage section 47 to flow through the gas supply pipe. The tip of the gas supply pipe is connected to nozzle 42 described above.

[0074] The shielding plate 48 has a disk-like shape of any thickness with an opening in the center, and is attached approximately horizontally to the lower end of the support shaft 44. The lower surface of the shielding plate 48 serves as a substrate-facing surface that faces the surface Wf of the substrate W and is approximately parallel to the surface Wf of the substrate W. The shielding plate 48 is formed to have a diameter equal to or greater than the diameter of the substrate W. The shielding plate 48 is provided so that the nozzle 42 is positioned at its opening. A shielding plate rotation mechanism including an electric motor and the like is connected to the shielding plate 48. The shielding plate rotation mechanism rotates the shielding plate 48 around the rotation axis C1 relative to the support shaft 44 in response to an operation rotation command from the control unit 13. The shielding plate rotation mechanism can rotate in synchronization with the rotation of the substrate W during the sublimation process described below.

[0075] The gas tank 471 stores a gas that is at least inert to the substrate processing liquid (sublimable substance), more specifically, nitrogen gas. The nitrogen gas is adjusted to a temperature below the freezing point of the sublimable substance by a gas temperature adjustment unit 472. The temperature of the nitrogen gas is not particularly limited as long as it is below the freezing point of the sublimable substance, but can usually be set within a range of 0°C to 15°C. By setting the temperature of the nitrogen gas to 0°C or higher, water vapor present inside the chamber 11 can be prevented from solidifying and adhering to the surface Wf of the substrate W, thereby preventing adverse effects on the substrate W.

[0076] Furthermore, the nitrogen gas used in this embodiment is preferably a dry gas with a dew point of 0°C or lower. When nitrogen gas is sprayed onto a solidified film of the substrate processing liquid under atmospheric pressure, the sublimable substances contained in the solidified film sublimate into the nitrogen gas. Since nitrogen gas is continuously supplied to the solidified film, the partial pressure of the gaseous sublimable substances generated by sublimation in the nitrogen gas is maintained lower than the saturated vapor pressure of the gaseous sublimable substances at the temperature of the nitrogen gas, and at least the surface of the solidified film is filled with an atmosphere in which the gaseous sublimable substances exist at or below their saturated vapor pressure.

[0077] In this embodiment, nitrogen gas is used as the gas stored in the gas storage section 47, but the present invention is not limited to this as long as it is a gas inert to the sublimable substance. Examples of gases that can be used instead of nitrogen gas include argon gas, helium gas, and air (gas with a nitrogen gas concentration of 80% and an oxygen gas concentration of 20%). Alternatively, a mixed gas containing a plurality of these gases may be used. Alternatively, a dry inert gas in which the moisture content of these gases has been reduced to a certain value or less may be used. The moisture content of the dry inert gas is preferably 1000 ppm or less, more preferably 100 ppm or less, and particularly preferably 10 ppm or less. By keeping the moisture content of the dry inert gas at 1000 ppm or less, condensation during the sublimation process can be prevented.

[0078] Incidentally, gas supply unit 41 may have a configuration in which a substrate processing liquid supply unit is incorporated. In this case, nozzle 22 of the substrate processing liquid supply unit is provided at the tip of support shaft 44 so as to coexist with nozzle 42 for discharging an inert gas or the like. A supply pipe (not shown) for supplying the substrate processing liquid is also inserted inside support shaft 44, and this supply pipe is configured to communicate with piping 25. This allows the substrate processing liquid stored in substrate processing liquid storage unit 27 to flow through the supply pipe.

[0079] The splash prevention cup 12 is provided to surround the spin base 53. The splash prevention cup 12 is connected to a lifting drive mechanism (not shown) and is capable of moving up and down in the Z direction. When supplying the substrate processing liquid or IPA to the pattern-formed surface of the substrate W, the splash prevention cup 12 is positioned at a predetermined position as shown in FIG. 2 by the lifting drive mechanism, and surrounds the substrate W held by the chuck pins 54 from a lateral position. This makes it possible to collect liquids such as the substrate processing liquid and IPA that splash from the substrate W or the spin base 53.

[0080] The substrate processing apparatus 100 of this embodiment may further include, in the processing unit 1, a chemical liquid supply unit that supplies a chemical liquid to the pattern-formed surface of the substrate W, and a rinse liquid supply unit that supplies a rinse liquid to the pattern-formed surface.

[0081] The chemical liquid supply unit and the rinse liquid supply unit may include, for example, a nozzle, an arm, a pivot, piping, a valve, and a chemical liquid storage tank, similar to the IPA supply unit 31. Therefore, detailed description of these components will be omitted. Examples of chemical liquids supplied by the chemical liquid supply unit include those containing at least one of sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, acetic acid, aqueous ammonia, hydrogen peroxide, organic acids (e.g., citric acid, oxalic acid, etc.), organic alkalis (e.g., TMAH (tetramethylammonium hydroxide)), surfactants, and corrosion inhibitors. Examples of rinse liquids supplied by the rinse liquid supply unit include DIW, carbonated water, electrolytic ionized water, hydrogen water, ozone water, and diluted hydrochloric acid (e.g., about 10 to 100 ppm).

[0082] <Control unit configuration> The control unit 13 is electrically connected to each part of the processing unit 1 (see Figures 2 to 4) and controls the operation of each part. The control unit 13 is composed of a computer having an arithmetic processing unit and a memory. The arithmetic processing unit uses a CPU that performs various arithmetic processing. The memory also includes a ROM, which is a read-only memory that stores a substrate processing program, a RAM, which is a read / write memory that stores various information, and a magnetic disk that stores control software, data, etc. The magnetic disk pre-stores substrate processing condition information (processing recipe) corresponding to the substrate W, control condition information for controlling the processing unit 1, etc. The CPU reads the substrate processing condition information, control condition information, etc. into the RAM and controls each part of the processing unit 1 according to the contents thereof.

[0083] (Substrate processing method) Next, a substrate processing method using the substrate processing apparatus 100 of this embodiment will be described below with reference to FIGS. FIG. 5 is a flowchart illustrating a substrate processing method using the substrate processing apparatus 100 according to this embodiment. FIG. 6(a) is a schematic diagram illustrating the state of the substrate W after the substrate processing liquid supply process is completed, and FIG. 6(b) is a schematic diagram illustrating the state of the substrate W after the thinning process is completed. FIG. 7(a) is a schematic diagram illustrating the state of the substrate W at the start of the solidification process, FIG. 7(b) is a schematic diagram illustrating the state where a solidified film 63 has been formed on the surface Wf of the substrate W, and FIG. 7(c) is a schematic diagram illustrating the state where the solidified film 63 has been removed by sublimation. FIG. 8 is a graph illustrating an example of an image of the reduction in thickness of the liquid film (thin film) of the substrate processing liquid on the substrate W due to evaporation of the solvent.

[0084] A concave-convex pattern Wp has been formed on the substrate W in a previous process (see FIG. 6(a) and the like). The pattern Wp has convex portions Wp1 and concave portions Wp2. In this embodiment, the convex portions Wp1 have a height in the range of 100 nm to 600 nm, for example, and a width in the range of 5 nm to 50 nm. The shortest distance between two adjacent convex portions Wp1 (the shortest width of the concave portions Wp2) is in the range of 5 to 150 nm, for example. The aspect ratio of the convex portions Wp1, i.e., the value obtained by dividing the height by the width (height / width), is in the range of 5 to 35, for example.

[0085] The substrate processing method according to this embodiment includes a substrate loading / substrate rotation start step S1, a chemical liquid supply step S2, a rinsing liquid supply step S3, a replacement liquid supply step S4, a substrate processing liquid supply step S5, a thinning step S6, a solidification step S7, a sublimation step S8, and a substrate rotation stop / substrate unloading step S9. Unless otherwise specified, each of these steps is performed under atmospheric pressure. Here, atmospheric pressure refers to an environment of 0.7 to 1.3 atmospheres, with standard atmospheric pressure (1 atmosphere, 1013 hPa) at its center. In particular, when the substrate processing apparatus 100 is disposed in a clean room with a positive pressure, the environment of the surface Wf of the substrate W becomes higher than 1 atmosphere.

[0086] Step S1: Substrate loading and substrate rotation start process First, an operator instructs the execution of a substrate processing program corresponding to a predetermined substrate W. Then, in preparation for loading the substrate W into the processing unit 1, the control unit 13 issues an operation command to perform the following operations: The rotation of the rotation drive unit 52 is stopped, and the chuck pins 54 are positioned to positions suitable for transferring the substrate W. The valves 26, 36, and 46 are closed, and the nozzles 22, 32, and 42 are positioned to their respective retracted positions. The chuck pins 54 are then opened by an opening / closing mechanism (not shown).

[0087] An unprocessed substrate W, which is stored in a sealed state in a container C of the indexer part 120, is carried into the processing unit 1 by the first transport part 122 and the second transport part 111 and placed on the chuck pins 54, and then the chuck pins 54 are closed by an opening / closing mechanism (not shown). This causes the unprocessed substrate W to be held by the substrate holding part 51. The unprocessed substrate W is held by the substrate holding part 51 so as to be in a substantially horizontal position.

[0088] Next, in response to an operation command from the control unit 13, the rotation driver 52 of the substrate holder 51 rotates the spin base 53. This causes the substrate W held by the chuck pins 54 above the spin base 53 to rotate about the rotation axis. The rotation speed (number of rotations) of the spin chuck 55 (the rotation speed (number of rotations) of the substrate W) can be set, for example, within a range of approximately 10 rpm to 3000 rpm, preferably 800 to 1200 rpm.

[0089] Step S2: Chemical solution supply process Next, while the substrate W is being rotated by the substrate holder 51, a chemical solution is supplied from the chemical solution supply unit onto the front surface Wf of the substrate W in response to an operation command from the control unit 13. This etches the native oxide film formed on the front surface Wf of the substrate W. After etching is completed, the supply of the chemical solution is stopped.

[0090] Step S3: Rinse liquid supply process Next, while the substrate W is being rotated by the substrate holder 51, a rinse liquid is supplied from the rinse liquid supply unit onto the surface Wf of the substrate W in response to an operation command from the control unit 13. The rinse liquid supplied to the surface Wf flows from near the center of the surface Wf of the substrate W toward the periphery of the substrate W due to centrifugal force generated by the rotation of the substrate W, and is spread over the entire surface Wf of the substrate W. As a result, the chemical liquid adhering to the surface Wf of the substrate W is removed by the supply of rinse liquid, and the entire surface Wf of the substrate W is covered with rinse liquid. After the entire surface Wf of the substrate W is covered with rinse liquid, the supply of rinse liquid is stopped.

[0091] Step S4: Substitute liquid supply process Next, while the substrate W is being rotated by the substrate holder 51, IPA is supplied as a substitute liquid onto the surface Wf of the substrate W. That is, the control unit 13 issues an operation command to the rotation drive unit 14 to position the nozzle 32 at the center of the surface Wf of the substrate W. Then, the control unit 13 issues an operation command to the valve 36 to open the valve 36. As a result, IPA is supplied from the IPA tank 37 to the surface Wf of the substrate W via the pipe 35 and the nozzle 32.

[0092] The IPA supplied to the surface Wf of the substrate W flows from near the center of the surface Wf of the substrate W toward the periphery of the substrate W due to centrifugal force generated by the rotation of the substrate W, and is dispersed over the entire surface Wf of the substrate W. As a result, the rinse liquid adhering to the surface Wf of the substrate W is removed by the supplied IPA, and the entire surface Wf of the substrate W is covered with IPA. The rotation speed of the substrate W is preferably set so that the thickness of the IPA film over the entire surface Wf is greater than the height of the protrusions Wp1. The amount of IPA supplied is not particularly limited and can be set appropriately. At the end of the replacement liquid supply process, the control unit 13 issues an operation command to the valve 36 to close the valve 36. The control unit 13 also issues an operation command to the rotation drive unit 14 to position the nozzle 32 at the retracted position.

[0093] Step S5: Substrate processing liquid supply process (supply process) Next, a substrate processing liquid is supplied to the front surface Wf of the substrate W to which the IPA is attached. That is, the control unit 13 issues an operation command to the rotation drive unit 52 to rotate the substrate W around the axis A1 at a constant speed. Next, the control unit 13 issues an operation command to the swivel drive unit 14 to position the nozzle 22 at the center of the surface Wf of the substrate W. Then, the control unit 13 issues an operation command to the valve 26 to open the valve 26. As a result, the substrate processing liquid is supplied from the substrate processing liquid storage tank 271 to the surface Wf of the substrate W via the piping 25 and the nozzle 22. The substrate processing liquid supplied to the surface Wf of the substrate W flows from near the center of the surface Wf of the substrate W toward the peripheral edge of the substrate W due to centrifugal force generated by the rotation of the substrate W, and is spread over the entire surface Wf of the substrate W. As a result, as shown in FIG. 6( a), the IPA adhering to the surface Wf of the substrate W is removed by the supply of the processing liquid, and the entire surface Wf of the substrate W is covered with the substrate processing liquid, forming a liquid film 60 of the substrate processing liquid.

[0094] When the substrate processing liquid supplying process is completed, the control unit 13 issues an operation command to the valve 26 to close the valve 26. The control unit 13 also issues an operation command to the rotation drive unit 14 to position the nozzle 22 at the retracted position.

[0095] Step S6: Thinning process Subsequently, the liquid film 60 of the substrate processing liquid formed on the front surface Wf of the substrate W is thinned. That is, the control unit 13 issues an operation command to the rotation drive unit 52 to rotate the substrate W around the axis A1 at a constant speed (first rotation speed). As a result, the excess substrate processing liquid is shaken off from the surface Wf of the substrate W by utilizing the action of centrifugal force generated by the rotation of the substrate W. By shaking off the liquid from the surface Wf of the substrate W, the liquid film 60 can be made into a thin film 61 with an optimum thickness, as shown in FIG. 6(b). Note that in the substrate processing liquid supply step, if the liquid film 60 can be made thin by controlling the amount of substrate processing liquid supplied, the rotation speed of the substrate W, etc., this step may be omitted.

[0096] In this step, the first rotation speed of the substrate W is set according to the film thickness of the liquid film 60. The first rotation speed is usually set in the range of 100 rpm or more and 1500 rpm or less, preferably in the range of 100 rpm or more and 1000 rpm or less, and more preferably in the range of 100 rpm or more and 500 rpm or less.

[0097] Step S7: Solidification process Next, the solvent is evaporated from the thin film 61 of the substrate processing liquid to precipitate a sublimable substance, thereby forming a solidified film. That is, the control unit 13 issues an operation command to the rotation drive unit 52 to rotate the substrate W around the axis A1 at a second rotation speed that is faster than the first rotation speed. Because the vapor pressure of the solvent is higher than the vapor pressure of the sublimable substance corresponding to the solute, the solvent evaporates at a faster evaporation rate than the evaporation rate of the sublimable substance. Therefore, as shown in FIG. 7(a), the solvent in the thin film 61 begins to evaporate. Then, as shown in FIG. 8, the concentration of the sublimable substance gradually increases, and the film thickness of the thin film 61 gradually decreases.

[0098] Furthermore, when the sublimable substance in the thin film 61 becomes supersaturated, the sublimable substance begins to precipitate, and a solidified film 62 is formed from the surface layer portion of the thin film 61, and then, as shown in Fig. 7(b), a solidified film 63 is formed to cover the entire surface Wf of the substrate W. The thickness of the solidified film 63 can be controlled by adjusting the concentration of the sublimable substance in the substrate processing solution.

[0099] In this process, the second rotation speed of the substrate W is set to be faster than the first rotation speed and is within the range of 500 rpm or more and 3000 rpm or less, preferably within the range of 500 rpm or more and 2000 rpm or less, and more preferably within the range of 500 rpm or more and 1500 rpm or less.

[0100] The thickness of the solidified film 63 can be controlled by adjusting the concentration of the sublimable substance in the substrate processing solution. Furthermore, in the present invention, by using methyl 5-bromo-2-furancarboxylate as the sublimable substance, the range of solidified film thicknesses that can effectively suppress pattern collapse can be relatively widened compared to conventional sublimable substances. That is, with the substrate processing method of the present invention, the range of conditions for effectively suppressing pattern collapse with respect to the thickness of the solidified film 63 can be set wide, resulting in an excellent process window.

[0101] Step S8: Sublimation process Subsequently, the solidified film 63 formed on the surface Wf of the substrate W is sublimated and removed. That is, the control unit 13 issues an operation command to the lifting drive unit 16, causing the lifting mechanism 49 to lower the nozzle 42 and the shielding plate 48 until the distance between them and the surface Wf of the substrate W reaches a preset value, and bring them closer to the substrate W. After the nozzle 42 and the shielding plate 48 have approached the surface Wf of the substrate W to the set distance, the control unit 13 rotates the shielding plate 48 at a constant speed around the axis A1 so as to synchronize with the substrate W.

[0102] Next, the control unit 13 issues an operation command to the valve 46, which opens the valve 46. As a result, the inert gas is supplied from the gas tank 471 toward the surface Wf of the substrate W via the pipe 45 and the nozzle 42. At this time, the substrate W and the shielding plate 48 are rotating synchronously, and therefore the centrifugal force generated by this rotation causes the inert gas to flow from near the center of the surface Wf of the substrate W toward the periphery of the substrate W, and diffuse over the entire surface Wf of the substrate W. This increases the contact speed between the solidified film 63 and the inert gas, and promotes sublimation of the solidified film 63.

[0103] Furthermore, the air present on the surface Wf of the substrate W can be replaced with an inert gas. By replacing the air with an inert gas, the solidified film 63 formed on the surface Wf is placed under a flow of inert gas, preventing it from being exposed to air, etc., and the solidified film 63 can be sublimated while maintaining a low temperature in the space between the substrate W and the shielding plate 48. As the solidified film 63 sublimes, heat of sublimation is removed, and the solidified film 63 is maintained at a temperature below the freezing point (melting point) of the sublimable substance. Therefore, melting of the sublimable substance contained in the solidified film 63 can be effectively prevented. As a result, as shown in FIG. 7(c), there is no liquid phase between the patterns on the surface Wf of the substrate W, and the substrate W can be dried while suppressing pattern collapse.

[0104] In this process, the rotation speed of the substrate W and the shielding plate 48 is not particularly limited, but is usually set within the range of 500 rpm or more and 3000 rpm or less, preferably 500 rpm or more and 2000 rpm or less, and more preferably 500 rpm or more and 1500 rpm or less.

[0105] The flow rate of the inert gas is preferably in the range of 200 L / min or less, more preferably in the range of 40 L / min to 200 L / min, and even more preferably in the range of 40 L / min to 50 L / min. By setting the flow rate of the inert gas to 200 L / min or less, it is possible to prevent the pattern from collapsing due to the spraying of the inert gas. Furthermore, the ejection time of the inert gas can be appropriately set depending on the sublimation time of the sublimable substance.

[0106] When a predetermined sublimation time has elapsed since the start of the sublimation step S8, the control unit 13 issues an operation command to the valve 46 to close the valve 46.

[0107] Step S9: Stopping the rotation of the substrate and removing the substrate After the sublimation step S8 is completed, the control unit 13 issues an operation command to the rotation drive unit 52 to stop the rotation of the spin base 53. The control unit 13 also controls the shielding plate rotation mechanism to stop the rotation of the shielding plate 48, and controls the elevation drive unit 16 to raise the shielding plate 48 from the shielding position and position it at the retracted position.

[0108] Thereafter, the second transfer part 111 enters the internal space of the chamber 11 and carries the processed substrate W, which has been released from the chuck pins 54, out of the chamber 11, thereby completing a series of substrate drying processes.

[0109] As described above, in this embodiment, by using a substrate processing solution containing methyl 5-bromo-2-furancarboxylate as a sublimable substance, pattern collapse on the substrate W can be effectively suppressed compared to conventional sublimation drying techniques using sublimable substances. In particular, this embodiment can effectively suppress pattern collapse even in patterns with extremely low mechanical strength. The pattern collapse rate is preferably 20% or less, more preferably 16% or less, and particularly preferably 10% or less. The collapse rate can be calculated, for example, by calculating the collapse rates in any seven regions using the following formula and then averaging the calculated values. Collapse rate (%) = (number of collapsed convex parts in any area) ÷ (total number of convex parts in that area) × 100

[0110] (Variation) The above description has been given of preferred embodiments of the present invention. However, the present invention is not limited to these embodiments and can be implemented in various other forms. Other main forms are exemplified below.

[0111] In the above embodiment, the sublimation step S8 is performed after the solidification step S7 is completed. However, the present invention is not limited to this embodiment. For example, the sublimation step S8 may be started after the start of the solidification step S7 and may be performed in parallel with the solidification step S7. As described above, the solidified film is formed from the surface layer of the liquid film as the sublimable substance is precipitated due to evaporation of the solvent. Therefore, the sublimation step S8 may be started before the end of the solidification step S7. This allows the substrate W to be dried by sublimation in a short period of time.

[0112] In the above embodiment, the gas supply unit is provided with a shielding plate. However, the present invention is not limited to this. For example, the sublimation step S8 may be performed using a gas supply unit that does not have a shielding plate.

[0113] In the above-described embodiment, the solidification step S7 is described as forming a solidified film by rotating the substrate W about the axis A1 at a rotation speed faster than that in the thinning step S6. However, the present invention is not limited to this example. For example, the substrate W may be rotated about the axis A1 at a rotation speed faster than that in the thinning step S6, and after the deposition of the sublimable substance, a solidified film may be formed while supplying an inert gas toward the surface Wf of the substrate W. Note that "after the deposition of the sublimable substance" refers to the time when the sublimable substance begins to deposit in the liquid film (i.e., when the liquid film of the substrate processing liquid becomes supersaturated), as well as the period from the deposition of the sublimable substance until the formation of the solidified film.

[0114] The means for supplying the inert gas in the solidification step S7 can be, for example, the above-mentioned gas supply unit 41. Furthermore, the gas supply unit 41 may be one that does not include the shielding plate 48.

[0115] The inert gas is not particularly limited, and examples thereof include nitrogen gas, argon gas, helium gas, and air (a gas with a nitrogen gas concentration of 80% and an oxygen gas concentration of 20%). Alternatively, a mixed gas of these gases may be used. Alternatively, a dry inert gas in which the moisture content of these gases has been reduced to a certain value or less may be used. The moisture content of the dry inert gas is preferably 1000 ppm or less, more preferably 100 ppm or less, and particularly preferably 10 ppm or less.

[0116] The flow rate of the sprayed inert gas is preferably 200 L / min or less, more preferably 40 L / min to 200 L / min, and even more preferably 40 L / min to 50 L / min. By setting the flow rate of the inert gas to 200 L / min or less, it is possible to prevent the pattern from collapsing due to the spraying of the inert gas. Furthermore, the spray time of the inert gas can be appropriately set depending on the time required to form the solidified film.

[0117] The temperature of the inert gas is preferably in the range of -50°C or higher and 100°C or lower, more preferably in the range of 0°C or higher and 50°C or lower, and particularly preferably in the range of 20°C or higher and 50°C or lower. When the temperature of the inert gas is 20°C or higher, condensation on the substrate can be prevented. [Example]

[0118] Preferred examples of the present invention are described in detail below. However, the materials and blending amounts described in the examples are not intended to limit the scope of the present invention unless otherwise specified.

[0119] (patterned substrate) A silicon substrate with a model pattern formed on its surface was prepared as a patterned substrate, and a coupon (specimen) measuring 1 cm on each side was cut from the silicon substrate. The model pattern used was an array of cylinders with a height of approximately 300 nm.

[0120] Example 1 In this example, a coupon cut out from the above-mentioned silicon substrate was subjected to a sublimation drying process according to the procedure described below, and the effect of suppressing pattern collapse was evaluated.

[0121] First, the coupon was immersed in 10% by mass hydrofluoric acid for 20 seconds (chemical solution supply step), then rinsed by immersing in DIW for 1 minute (rinse solution supply step).Furthermore, after rinsing with DIW, the coupon was immersed in IPA for 1 minute to replace the DIW present on the patterned surface of the coupon with IPA (replacement solution supply step).

[0122] Next, the coupon with the remaining IPA on its surface was immersed in a substrate processing solution (liquid temperature: 25°C) at room temperature (25°C) and atmospheric pressure (1 atm) for 30 seconds to replace the IPA on the patterned surface of the coupon with the substrate processing solution (substrate processing solution supply step).The substrate processing solution used was a mixture of 3.2 vol% methyl 5-bromo-2-furancarboxylate (a sublimable substance) and IPA.

[0123] Furthermore, the coupon after the supply of the substrate processing liquid was rotated around the rotation axis at a rotation speed of 10 rpm for 5 seconds to thin the liquid film of the substrate processing liquid on the pattern-formed surface (thinning step).

[0124] Next, the coupon after the thinning process was rotated around the rotation axis at a rotation speed of 1500 rpm, the IPA was evaporated, methyl 5-bromo-2-furancarboxylate was precipitated, and a solidified film consisting of the methyl 5-bromo-2-furancarboxylate was formed (solidification process).

[0125] After a solidified film was formed on the patterned surface of the coupon, nitrogen gas was sprayed onto the solidified film to sublimate it (sublimation process). The sublimation process was carried out while the coupon was rotated around its axis at a rotation speed of 1500 rpm. The flow rate of the nitrogen gas was 40 L / min. The total processing time for the solidification and sublimation processes was 120 seconds.

[0126] The pattern collapse rate was calculated from SEM images of the coupons obtained after sublimation drying, and the effect of suppressing pattern collapse on the patterned surface was evaluated based on the collapse rate. The collapse rate was calculated by averaging the collapse rates in seven arbitrary regions using the following formula. Collapse rate (%) = (number of collapsed convex parts in any area) ÷ (total number of convex parts in that area) × 100

[0127] As a result, the collapse rate after drying was 17.23% compared to the pattern-formed surface of the coupon before drying. This confirmed that when methyl 5-bromo-2-furancarboxylate was used as the sublimable substance, pattern collapse could be suppressed extremely well and it was effective for sublimation drying.

[0128] Example 2 In this example, the concentration of methyl 5-bromo-2-furancarboxylate was changed to 4.8 vol% relative to the total volume of the substrate processing solution. Otherwise, the same procedure as in Example 1 was repeated to evaluate the effect of suppressing pattern collapse on the patterned surface. As a result, the collapse rate was 9.49%.

[0129] Example 3 In this example, the concentration of methyl 5-bromo-2-furancarboxylate was changed to 6.3 vol% relative to the total volume of the substrate processing solution. Otherwise, the same procedure as in Example 1 was repeated to evaluate the effect of suppressing pattern collapse on the patterned surface. The resulting collapse rate was 15.94%.

[0130] (Comparative Example 1) In this comparative example, camphor, represented by the following chemical formula, was used as the sublimable substance, and its concentration was changed to 0.62 vol% relative to the substrate processing solution. Other than that, the same procedure as in Example 1 was repeated to evaluate the effect of suppressing pattern collapse on the patterned surface. As a result, the collapse rate was 60.85%.

[0131] [ka]

[0132] (Comparative Example 2) In this comparative example, the camphor concentration was changed to 0.71 vol% in the substrate processing solution. Otherwise, the effect of suppressing pattern collapse on the pattern-formed surface was evaluated in the same manner as in Comparative Example 1. As a result, the collapse rate was 40.57%.

[0133] (Comparative Example 3) In this comparative example, the camphor concentration was changed to 0.99 vol% in the substrate processing solution. Otherwise, the effect of suppressing pattern collapse on the pattern-formed surface was evaluated in the same manner as in Comparative Example 1. As a result, the collapse rate was 28.82%.

[0134] Comparative Example 4 In this comparative example, the camphor concentration was changed to 2.41 vol% of the substrate processing solution. Otherwise, the effect of suppressing pattern collapse on the pattern-formed surface was evaluated in the same manner as in Comparative Example 1. As a result, the collapse rate was 55.70%.

[0135] (Comparative Example 5) In this comparative example, the camphor concentration was changed to 3.23 vol% of the substrate processing solution. Otherwise, the effect of suppressing pattern collapse on the pattern-formed surface was evaluated in the same manner as in Comparative Example 1. As a result, the collapse rate was 60.78%.

[0136] (Comparative Example 6) In this comparative example, the camphor concentration was changed to 4.76 vol% of the substrate processing solution. Otherwise, the effect of suppressing pattern collapse on the pattern-formed surface was evaluated in the same manner as in Comparative Example 1. As a result, the collapse rate was 83.55%.

[0137] [Table 1]

[0138] (result) As can be seen from Table 1, in Examples 1 to 3, in which methyl 5-bromo-2-furancarboxylate was used as the sublimable substance, the pattern collapse rate could be suppressed. Furthermore, as can be seen from the results of Examples 1 to 3, when methyl 5-bromo-2-furancarboxylate was used as the sublimable substance, a wide range of conditions for satisfactorily suppressing pattern collapse could be set, and it was confirmed that the process window was excellent. On the other hand, in Comparative Examples 1 to 6, in which camphor was used as the sublimable substance, the pattern collapse rate was higher than in Examples 1 to 3, and it was confirmed that pattern collapse could not be sufficiently suppressed. [Industrial Applicability]

[0139] The present invention can be applied to a drying technique for removing liquid adhering to a pattern-formed surface of a substrate, and to a general substrate processing technique for processing the surface of a substrate using the drying technique. [Explanation of symbols]

[0140] 1 Processing Unit 13 Control Unit 21 Processing liquid supply unit 27 Substrate processing liquid storage section 41 Gas supply section 47 Gas reservoir 48 Breaker 51 Board holding part 52 Rotation drive unit 60 liquid film 61 Thin Film 62, 63 Solidified film 271 Substrate processing liquid storage tank 272 Temperature adjustment section 275 Nitrogen Gas Tank 471 Gas Tank 472 Gas temperature control unit W substrate Wf (substrate) surface Wb (back side of board) Wp (surface of board) pattern Wp1 (pattern) convex part Wp2 (pattern) recess

Claims

1. A substrate processing method for processing a pattern-formed surface of a substrate, comprising: a supplying step of supplying a substrate processing solution containing a sublimable substance and a solvent onto the pattern forming surface; a solidification step of evaporating a solvent in the liquid film of the substrate processing liquid supplied to the pattern formation surface in the supply step to precipitate the sublimable substance and form a solidified film containing the sublimable substance; a sublimation step of sublimating the solidified film and removing the solidified film; Including, The method for processing a substrate, wherein the sublimable material comprises methyl 5-bromo-2-furancarboxylate.

2. 2. The substrate processing method according to claim 1, a thinning step of thinning the liquid film of the substrate processing liquid supplied in the supply step onto the pattern formation surface by rotating the substrate at a first rotation speed around a rotation axis parallel to a direction perpendicular to the pattern formation surface, The solidifying step is a step of rotating the substrate about the rotation axis at a second rotation speed that is faster than the first rotation speed, thereby evaporating the solvent in the liquid film.

3. 2. The substrate processing method according to claim 1, The solidification step of the substrate processing method includes supplying an inert gas to the pattern formation surface after the deposition of the sublimable substance, thereby promoting the formation of the solidified film.

4. 2. The substrate processing method according to claim 1, A substrate processing method, wherein the content of the sublimable substance is in the range of 3.1 vol % or more and 6.3 vol % or less with respect to the total volume of the substrate processing solution.

5. 3. The substrate processing method according to claim 2, A substrate processing method, wherein the solvent has a vapor pressure at room temperature greater than that of the sublimable substance.

6. 6. The substrate processing method according to claim 5, The substrate processing method, wherein the solvent is at least one of methanol, butanol, isopropyl alcohol, and acetone.

7. A substrate processing apparatus for processing a pattern-formed surface of a substrate, comprising: a substrate holder that holds the substrate rotatably around a rotation axis that is parallel to a direction perpendicular to the pattern formation surface; a supply unit that supplies a substrate processing liquid containing a sublimable substance and a solvent to a pattern formation surface of the substrate held by the substrate holding unit; a sublimation unit that sublimes the solidified film containing the sublimable substance and removes the solidified film; Equipped with The substrate holder includes: a solvent in the liquid film of the substrate processing liquid supplied to the pattern formation surface by the supply unit is evaporated by rotating the substrate about the rotation axis, thereby precipitating the sublimable substance and forming a solidified film containing the sublimable substance; In the substrate processing apparatus, the sublimable substance in the substrate processing solution supplied by the supply unit contains methyl 5-bromo-2-furancarboxylate.

8. 8. The substrate processing apparatus according to claim 7, The substrate holder includes: rotating the substrate about the rotation axis at a first rotation speed to thin the liquid film of the substrate processing liquid supplied by the supply unit to the pattern formation surface; a substrate processing apparatus for rotating the substrate about the rotation axis at a second rotation speed that is faster than the first rotation speed when thinning the liquid film of the substrate processing liquid, thereby evaporating a solvent in the liquid film.

9. 8. The substrate processing apparatus according to claim 7, the sublimation unit is a gas supply unit that supplies an inert gas toward the pattern formation surface, The substrate processing apparatus, wherein the gas supply unit also promotes the formation of the solidified film by supplying the inert gas toward the pattern formation surface after deposition of the sublimable substance during the formation of the solidified film.

10. 8. The substrate processing method according to claim 7, A substrate processing method, wherein the content of the sublimable substance is in the range of 3.1 vol % or more and 6.3 vol % or less with respect to the total volume of the substrate processing solution.

11. 9. The substrate processing apparatus according to claim 8, The substrate processing apparatus uses, as the solvent, a solvent having a vapor pressure at room temperature greater than that of the sublimable substance.

12. The substrate processing apparatus according to claim 11, The substrate processing apparatus, wherein the solvent is at least one of methanol, butanol, isopropyl alcohol, and acetone.

13. 1. A substrate processing liquid for use in removing a liquid on a substrate having a patterned surface, comprising: a sublimable material; a solvent; Including, The substrate processing solution, wherein the sublimable substance comprises methyl 5-bromo-2-furancarboxylate.

14. The substrate processing solution according to claim 13, The substrate processing solution has a content of the sublimable substance in the range of 3.1 vol % to 6.3 vol % based on the total volume of the substrate processing solution.

15. The substrate processing solution according to claim 13, The substrate processing liquid, wherein the solvent has a vapor pressure at room temperature greater than that of the sublimable substance.

16. The substrate processing solution according to claim 15, The substrate processing solution, wherein the solvent is at least one of methanol, butanol, isopropyl alcohol, and acetone.

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