Substrate processing method

Abstract

The present invention provides a substrate processing method that can prevent or reduce the collapse of patterns that occurs when residual processing liquid inside the solidified film evaporates and forms voids. [Solution] The present invention relates to a substrate processing method for processing a pattern-forming surface of a substrate W, comprising: a supply step S3 for supplying a processing liquid containing a sublimable substance and a solvent to the pattern-forming surface; a solidification film forming step S4 for evaporating the solvent from a liquid film 103 of the processing liquid supplied to the pattern-forming surface to precipitate the sublimable substance and form a solidified film 106; a freezing step S5 (S5') for freezing residual processing liquid 105 remaining inside during or after the formation of the solidified film 106 in the solidification film forming step S4; and a sublimation step S6 (S6') for sublimating the solidified film 106 and the frozen residual processing liquid 105.

Description

Technical Field

[0001] The present invention relates to a substrate processing method for removing liquid adhered to various substrates such as a semiconductor substrate, a glass substrate for a photomask, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a substrate for a FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, and a substrate for a magneto-optical disk (hereinafter referred to as "substrate").

Background Art

[0002] In recent years, with the development of next-generation devices using miniaturization and new materials, when performing substrate processing on the substrate surface, a technique for suppressing pattern collapse has been demanded. Among substrate processing, the sublimation drying technique of solidifying a processing liquid to form a solidified film and then sublimating and removing the solidified film can prevent or reduce the action of the Laplace pressure derived from the processing liquid on the pattern. Therefore, this technique is regarded as promising as a technique capable of suppressing pattern collapse.

[0003] Here, as a drying technique for the purpose of preventing pattern collapse, for example, Patent Document 1 discloses a substrate drying method for removing liquid on a substrate having a concavo-convex pattern formed on its surface and drying the substrate. According to this substrate drying method, a processing liquid containing a sublimable substance and a solvent is supplied to the substrate, the solvent in the processing liquid is dried to precipitate the sublimable substance, and thereby a solidified film is formed that fills the concave portions of the pattern with the sublimable substance in a solid state. Further, the substrate is heated to a temperature higher than the sublimation temperature of the sublimable substance to remove the solidified film from the substrate. Thereby, in Patent Document 1, it is said that the stress that tries to collapse the convex portions of the pattern that may be caused by the surface tension of the liquid on the substrate is suppressed from acting on the convex portions of the pattern, and pattern collapse can be prevented.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] However, even when using the sublimation drying method described above, it may not be possible to completely prevent the collapse of the pattern. In other words, the solidified film is formed when the solvent evaporates from the surface of the liquid film of the processing solution, and the supersaturated sublimable substance begins to precipitate in the surface layer of the liquid film. That is, since the solidified film begins to form from the surface layer of the liquid film of the processing solution, some processing solution may remain inside the solidified film. When the processing solution remaining inside the solidified film evaporates, voids (cavities) are formed. And when these voids are formed, the surface tension of the processing solution acts on the pattern, resulting in the problem of the pattern collapsing.

[0006] The present invention has been made in view of the above-mentioned problems, and its objective is to provide a substrate processing method that can prevent or reduce the collapse of patterns that occurs when the processing liquid remaining inside the solidified film evaporates and forms voids. [Means for solving the problem]

[0007] The substrate processing method according to the present invention is a substrate processing method for processing a pattern-forming surface of a substrate in order to solve the above problems, and is characterized by comprising: a supply step of supplying a processing liquid containing a sublimable substance and a solvent to the pattern-forming surface; a solidification film formation step of evaporating the solvent from the liquid film of the processing liquid supplied to the pattern-forming surface to precipitate the sublimable substance and form a solidified film; a freezing step of freezing residual processing liquid remaining inside during or after the formation of the solidified film in the solidification film formation step; and a sublimation step of sublimating the solidified film and the frozen residual processing liquid and removing them from the pattern-forming surface.

[0008] According to the above configuration, liquid present on the pattern-forming surface of the substrate is removed while suppressing or preventing the collapse of the pattern by the principle of sublimation drying. Specifically, a processing liquid containing a sublimable substance and a solvent is supplied to the pattern-forming surface, a liquid film of the processing liquid is formed (supply step), and then the liquid film is solidified (solidification film formation step). Furthermore, in the above configuration, a freezing step is performed before the sublimation step of the solidified film. In the freezing step, the remaining processing liquid remaining inside the solidified film being formed in the solidification film formation step, or the solidified film formed after the solidification film formation step, is frozen to prevent the remaining processing liquid from evaporating and forming voids. As a result, in the above configuration, when the remaining processing liquid evaporates, its surface tension can act on the pattern and prevent it from collapsing. Furthermore, in the sublimation step, in addition to the solidified film, the remaining processing liquid frozen inside the solidified film is also sublimated and removed. Therefore, in the above configuration, substrate processing by sublimation drying can be performed while effectively reducing or preventing the collapse of the pattern.

[0009] In the above configuration, it is preferable that the freezing step is a step of cooling the solidified film at a temperature at least below the freezing point of the residual treatment liquid. Since the solidified film being formed in the solidified film formation step, or the solidified film after formation, is cooled at a temperature below the freezing point of the residual treatment liquid, the residual treatment liquid remaining inside the solidified film can be frozen effectively.

[0010] In the above configuration, the freezing step may also be a step of cooling the solidified film and freezing the residual treatment liquid by supplying a cooling gas that is at least inert to the sublimable substance to the solidified film.

[0011] In the above configuration, the freezing step may also be a step of supplying a cooling fluid to the surface of the substrate opposite to the pattern-forming surface, thereby cooling the solidified film through the substrate and freezing the residual treatment liquid.

[0012] In the above configuration, the freezing step may also be a step of cooling the solidified film through the substrate by bringing a cooling plate into contact with the surface of the substrate opposite to the pattern-forming surface, thereby freezing the residual treatment liquid.

[0013] Furthermore, in the above configuration, it is preferable that the sublimation step is a step of supplying a cooling fluid to the side of the substrate opposite to the pattern-forming surface, thereby cooling the solidified film through the substrate, while supplying a gas that is at least inert to the sublimable substance, at a temperature below the freezing point of the sublimable substance, toward the pattern-forming surface. According to the above configuration, by cooling the solidified film through the substrate with the cooling fluid, it is possible to prevent the residual treatment liquid frozen inside the solidified film from melting (or thawing). In other words, according to the above configuration, it is possible to sublimate the solidified film and the frozen residual treatment liquid while preventing the residual treatment liquid from becoming liquid, and the occurrence of pattern collapse can be further prevented. [Effects of the Invention]

[0014] According to the present invention, by freezing the residual treatment liquid remaining inside the solidified film containing a sublimable substance, it is possible to prevent the evaporation of the residual treatment liquid and the formation of voids inside the solidified film. This prevents or reduces the collapse of the pattern caused by the surface tension of the residual treatment liquid acting on the pattern during void formation. Furthermore, since the residual treatment liquid frozen inside the solidified film is sublimated along with the solidified film, it is possible to provide a substrate processing method that enables good substrate processing by sublimation drying while preventing or reducing the collapse of the pattern. [Brief explanation of the drawing]

[0015] [Figure 1] This is an explanatory diagram illustrating the schematic of a substrate processing apparatus according to the first embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view showing the basic structure of the substrate holding section and the cooling fluid supply section in a substrate processing apparatus. [Figure 3]FIG. 3(a) is a block diagram showing a schematic configuration of a processing liquid storage unit, and FIG. 3(b) is an explanatory diagram showing a specific configuration of the processing liquid storage unit. [Figure 4] It is a block diagram showing a schematic configuration of a gas storage unit in a substrate processing apparatus. [Figure 5] It is a block diagram showing a schematic configuration of a cooling fluid storage unit in a substrate processing apparatus. [Figure 6] It is a flowchart for explaining a substrate processing method using the substrate processing apparatus according to the first embodiment of the present invention. [Figure 7] FIG. 7(a) is a schematic diagram showing the state of a substrate at the end of a cleaning step, FIG. 7(b) is a schematic diagram showing the state of the substrate at the end of an IPA rinse step, and FIG. 7(c) is a schematic diagram showing the state of the substrate at the end of a supply step. [Figure 8] FIG. 8(a) is a schematic diagram showing the formation of a surface solidified layer of a sublimable substance on the surface of a liquid film of a processing liquid, FIG. 8(b) is a schematic diagram showing the Oswald growth of the surface solidified layer of the sublimable substance, and FIG. 8(c) is a schematic diagram showing the formation of a solidified film with residual processing liquid remaining inside. [Figure 9] FIG. 9(a) is a schematic diagram showing the freezing of residual processing liquid inside a solidified film, FIG. 9(b) is a schematic diagram showing the removal of the solidified film from the surface of a substrate, and FIG. 9(c) is a schematic diagram showing the removal of a frozen body from the surface of the substrate. [Figure 10] In the substrate processing apparatus according to the second embodiment of the present invention, it is a cross-sectional schematic diagram showing an overview of a substrate holding unit and a substrate contact cooling unit. [Embodiments for Carrying Out the Invention]

[0016] (First Embodiment) The first embodiment of the present invention will be described below.

[0017] [Substrate Processing Apparatus] The substrate processing apparatus according to the present embodiment can be used for various substrate processes, such as a cleaning process (including a rinse process) for removing contaminants such as particles adhering to the substrate, and a drying process after the cleaning process. The substrate processing apparatus of the present embodiment is a single wafer type substrate processing apparatus.

[0018] Here, in this specification, the "substrate" refers to various substrates such as a semiconductor substrate, a glass substrate for a photomask, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a substrate for a FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, and a substrate for a magneto-optical disk. Further, in this specification, the "pattern formation surface" means a surface on which a concavo-convex pattern is formed in an arbitrary region on the substrate, regardless of whether it is planar, curved, or concavo-convex. Also, in this specification, as an example of the substrate, one in which a circuit pattern or the like (hereinafter referred to as "pattern") is formed only on one main surface is described. Here, the pattern formation 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 "back surface". Also, 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 the present embodiment, the upper surface is described as the front surface.

[0019] The specific configuration of the substrate processing apparatus according to this embodiment will be described in more detail. As shown in Figure 1, the substrate processing apparatus 1 includes at least a chamber 10 which is a container for housing a substrate W, a substrate holding unit 20 which holds the substrate W, a control unit 30 which controls each part of the substrate processing apparatus 1, a processing liquid supply unit 40 which supplies processing liquid to the surface Wa of the substrate W, an IPA supply unit 50 which supplies IPA to the surface Wa of the substrate W, a gas supply unit 60 which supplies gas to the surface Wa of the substrate W, a splash prevention cup 11 which collects IPA, processing liquid, etc., a rotation drive unit 12 which independently rotates each of the arms described later, and a cooling unit 70 which cools the back surface Wb of the substrate W. The substrate processing apparatus 1 also includes a substrate loading / unloading means, a chuck pin opening / closing mechanism, and a wet cleaning means (none of which are shown). Note that only the parts used for drying are shown in Figure 1, and cleaning nozzles etc. used for cleaning are not shown, but the substrate processing apparatus 1 may include such nozzles etc. Figure 1 is an explanatory diagram illustrating the schematic of the substrate processing apparatus according to this embodiment. In Figure 1, the XYZ Cartesian coordinate axes are displayed as appropriate to clarify the directional relationships of the illustrated elements. In Figure 1, the XY plane represents the horizontal plane, and the +Z direction represents the vertically upward direction.

[0020] The various parts of the substrate processing apparatus 1 are described below. The substrate holding section 20 is a means for holding the substrate W, and as shown in Figure 2, it holds the substrate W in a horizontal position with the substrate surface Wa facing upward and rotates it. Figure 2 is a schematic cross-sectional view showing the general shape of the substrate holding section and the cooling fluid supply section in the substrate processing apparatus. This substrate holding section 20 has a spin chuck 23 in which a spin base 21 and a rotating support shaft 22 are integrally coupled. The spin base 21 has a substantially circular shape in plan view, and a hollow rotating support shaft 22 extending substantially vertically is fixed to its center. The rotating support shaft 22 is connected to the rotation axis of a chuck rotation mechanism 24 including a motor. The chuck rotation mechanism 24 is housed in a cylindrical casing 26, and the rotating support shaft 22 is rotatably supported by the casing 26 around a vertical rotation axis.

[0021] The chuck rotation mechanism 24 rotates the pivot shaft 22 around its axis of rotation, driven by the chuck drive unit (not shown) of the control unit 30. This causes the spin base 21, attached to the upper end of the pivot shaft 22, to rotate around its axis of rotation. The control unit 30 can control the chuck rotation mechanism 24 via the chuck drive unit to adjust the rotation speed of the spin base 21.

[0022] Multiple chuck pins 25 are erected near the periphery of the spin base 21 for gripping the peripheral edge of the substrate W. The number of chuck pins 25 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 are arranged at equal intervals along the periphery of the spin base 21 (see Figure 2). Each chuck pin 25 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 end face of the substrate W supported by the substrate support pin to hold the substrate W.

[0023] Furthermore, each chuck pin 25 can be switched between a pressed state, where the substrate holding pin presses against the outer edge surface of the substrate W, and a released state, where the substrate holding pin moves away from the outer edge surface of the substrate W. The state switching is performed in accordance with the operation command from the control unit 30 that controls the entire apparatus. More specifically, when loading or unloading the substrate W to the spin base 21, each chuck pin 25 is set to the released state, and when performing substrate processing on the substrate W, from the cleaning process to the removal process described later, each chuck pin 25 is set to the pressed state. When the chuck pin 25 is set to the pressed state, the chuck pin 25 grips the peripheral edge of the substrate W, and the substrate W is held in a horizontal position (XY plane) at a predetermined distance from the spin base 21. As a result, the substrate W is held horizontally with its surface Wa facing upward. Note that the method of holding the substrate W is not limited to this, and for example, the back surface Wb of the substrate W may be held by a suction method such as a spin chuck.

[0024] With the substrate W held in the spin chuck 23, or more specifically, with its peripheral edge held by the chuck pins 25 provided on the spin base 21, the chuck rotation mechanism 24 is activated, causing the substrate W to rotate around the vertical rotation axis A1.

[0025] The processing liquid supply unit 40 is a unit that supplies processing liquid to the surface Wa (pattern forming surface) of the substrate W held by the substrate holding unit 20. Specifically, as shown in Figure 1, the processing liquid supply unit 40 comprises at least a nozzle 41, an arm 42, a pivot shaft 43, a pipe 44, a valve 45, and a processing liquid storage unit 46.

[0026] As shown in Figures 3(a) and 3(b), the processing liquid storage unit 46 comprises at least a processing liquid storage tank 46a, a stirring unit 46b for stirring the processing liquid in the processing liquid storage tank 46a, a pressurizing unit 46c for pressurizing the processing liquid storage tank 46a and discharging the processing liquid, and a temperature control unit 46d for heating the processing liquid in the processing liquid storage tank 46a. Figure 3(a) is a block diagram showing the schematic configuration of the processing liquid storage unit 46, and Figure 3(b) is an explanatory diagram showing the specific configuration of the processing liquid storage unit 46.

[0027] The stirring unit 46b comprises a rotating unit 46i that stirs the processing liquid in the processing liquid storage tank 46a, and a stirring control unit 46e that controls the rotation of the rotating unit 46i. The rotating unit 46i is equipped with a propeller-shaped stirring blade at the tip of its rotating shaft (the lower end of the rotating unit 46i in Figure 3(b)). The stirring control unit 46e is electrically connected to the control unit 30. The control unit 30 issues an operation command to the stirring control unit 46e, causing the rotating unit 46i to rotate, which in turn stirs the processing liquid with the stirring blade, thereby homogenizing the concentration of sublimable substances (details of which will be described later) and the temperature of the processing liquid.

[0028] Furthermore, the method for making the concentration and temperature of the processing liquid in the processing liquid storage tank 46a uniform is not limited to the method described above, and known methods such as circulating the processing liquid by providing a separate circulation pump can be used.

[0029] The pressurized section 46c consists of a nitrogen gas tank 46f, which is the source of the gas that pressurizes the treated liquid storage tank 46a; a pump 46g for pressurizing the nitrogen gas; and piping 46h. The nitrogen gas tank 46f is connected to the treated liquid storage tank 46a by piping 46h, and the pump 46g is inserted into piping 46h.

[0030] The temperature control unit 46d is electrically connected to the control unit 30 and adjusts the temperature of the processing liquid stored in the processing liquid storage tank 46a by heating it according to the operation commands of the control unit 30. The temperature adjustment should be performed so that it is above the melting point of the processing liquid. This allows the processing liquid to be stored without solidifying. It is preferable that the upper limit of the temperature adjustment is lower than the boiling point of the processing liquid. Furthermore, the temperature control unit 46d is not particularly limited, and known temperature adjustment mechanisms such as resistance heaters, Peltier elements, and piping through temperature-adjusted water can be used. In this embodiment, the temperature control unit 46d has any configuration.

[0031] The processing liquid storage section 46 (more specifically, the processing liquid storage tank 46a) is connected to the nozzle 41 via piping 44, and a valve 45 is interposed in the middle of the piping 44.

[0032] A pressure sensor (not shown) is installed inside the processing liquid storage tank 46a and is electrically connected to the control unit 30. The control unit 30 maintains the pressure inside the processing liquid storage tank 46a at a predetermined pressure higher than atmospheric pressure by controlling the operation of the pump 46g based on the value detected by the pressure sensor. Meanwhile, the valve 45 is also electrically connected to the control unit 30 and is normally closed. The opening and closing of the valve 45 is also controlled by operation commands from the control unit 30. When the control unit 30 issues an operation command to the processing liquid supply unit 40 and opens the valve 45, the processing liquid is pumped from the pressurized processing liquid storage tank 46a and discharged from the nozzle 41 via the piping 44. This allows the processing liquid to be supplied to the surface Wa of the substrate W. As mentioned above, the processing liquid storage tank 46a is preferably airtight because it uses nitrogen gas pressure to pump the processing liquid.

[0033] The nozzle 41 is attached to the tip of a horizontally extending arm 42 and is positioned above the spin base 21. The rear end of the arm 42 is rotatably supported around axis J1 by a pivot shaft 43 extending in the Z direction, and the pivot shaft 43 is fixed inside the chamber 10. The arm 42 is connected to a pivot drive unit 12 via the pivot shaft 43. The pivot drive unit 12 is electrically connected to a control unit 30 and rotates the arm 42 around axis J1 according to operation commands from the control unit 30. As the arm 42 rotates, the nozzle 41 also moves.

[0034] The IPA supply unit 50 is a unit that supplies isopropyl alcohol (IPA) to the surface Wa (pattern forming surface) of the substrate W held by the substrate holding unit 20. Specifically, as shown in Figure 1, the IPA supply unit 50 comprises at least a nozzle 51, an arm 52, a pivot shaft 53, piping 54, a valve 55, and an IPA tank 56.

[0035] The IPA tank 56 is connected to the nozzle 51 via piping 54, with a valve 55 interposed in the middle of the piping 54. IPA is stored in the IPA tank 56, and the IPA in the IPA tank 56 is pressurized by a pressurizing means (not shown), and the IPA is sent from piping 54 towards the nozzle 51.

[0036] Valve 55 is electrically connected to the control unit 30 and is normally closed. The opening and closing of valve 55 is controlled by an operation command from the control unit 30. When valve 55 is opened by an operation command from the control unit 30, IPA is supplied through the piping 54 to the surface Wa of the substrate W from the nozzle 51.

[0037] The nozzle 51 is attached to the tip of a horizontally extending arm 52 and positioned above the spin base 21. The rear end of the arm 52 is rotatably supported around axis J2 by ​​a pivot shaft 53 extending in the Z direction, and the pivot shaft 53 is fixed inside the chamber 10. The arm 52 is connected to a pivot drive unit 12 via the pivot shaft 53. The pivot drive unit 12 is electrically connected to a control unit 30 and rotates the arm 52 around axis J2 according to operation commands from the control unit 30. As the arm 52 rotates, the nozzle 51 also moves.

[0038] In this embodiment, IPA is used in the IPA supply unit 50, but the present invention is not limited to IPA and may use any liquid that is soluble in sublimable substances and deionized water (DIW). Examples of substitutes for IPA in this embodiment include methanol, ethanol, acetone, benzene, carbon tetrachloride, chloroform, hexane, decalin, tetralin, acetic acid, cyclohexanol, ether, or hydrofluoroether.

[0039] The gas supply unit 60 is a unit that supplies gas to the surface Wa (pattern forming surface) of the substrate W held by the substrate holding unit 20. By supplying gas, the gas supply unit 60 cools the solidified film during or after its formation, thereby enabling the freezing of the residual processing liquid (details will be described later) remaining inside it. The gas supply unit 60 also enables the sublimation of the solidified film and the residual processing liquid after freezing. Specifically, as shown in Figure 1, the gas supply unit 60 comprises at least a nozzle 61, an arm 62, a pivot shaft 63, piping 64, a valve 65, and a gas storage unit 66.

[0040] As shown in Figure 4, the gas storage unit 66 comprises a gas tank 66a for storing gas and a gas temperature adjustment unit 66b for adjusting the temperature of the gas stored in the gas tank 66a. The same figure is a block diagram showing the schematic configuration of the gas storage unit 66. The gas temperature adjustment unit 66b is electrically connected to the control unit 30 and adjusts the temperature of the gas stored in the gas tank 66a by heating or cooling it according to the operation commands of the control unit 30. The gas temperature adjustment unit 66b is not particularly limited, and known temperature adjustment mechanisms such as a Peltier element or piping through temperature-controlled water can be used.

[0041] Furthermore, the gas storage section 66 (more specifically, the gas tank 66a) is connected to the nozzle 61 via piping 64, as shown in Figure 1, and a valve 65 is interposed in the middle of the piping 64. The gas in the gas storage section 66 is pressurized by a pressurizing means (not shown) and sent to the piping 64. Note that the pressurizing means can be achieved by pressurizing with a pump or the like, or by compressing and storing the gas in the gas storage section 66, so either pressurizing means may be used.

[0042] Valve 65 is electrically connected to the control unit 30 and is normally closed. The opening and closing of valve 65 is controlled by an operation command from the control unit 30. When valve 65 is opened by an operation command from the control unit 30, gas is supplied from nozzle 61 to the surface Wa of substrate W through piping 64.

[0043] The nozzle 61 is attached to the tip of a horizontally extending arm 62 and positioned above the spin base 21. The rear end of the arm 62 is rotatably supported around axis J3 by a pivot shaft 63 extending in the Z direction, and the pivot shaft 63 is fixed inside the chamber 10. The arm 62 is connected to a pivot drive unit 12 via the pivot shaft 63. The pivot drive unit 12 is electrically connected to a control unit 30 and rotates the arm 62 around axis J3 according to operation commands from the control unit 30. As the arm 62 rotates, the nozzle 61 also moves.

[0044] The gas tank 66a stores an inert gas that is inactive with respect to sublimable substances. When this inert gas is used to freeze the residual treatment liquid, the temperature of the inert gas is adjusted in the gas temperature control unit 66b to be below the freezing point of the residual treatment liquid, preferably within the range of -196°C to -89°C. When the inert gas is used to sublimate the solidified film and the frozen residual treatment liquid, the temperature of the inert gas is adjusted in the gas temperature control unit 66b to be below the freezing point of the sublimable substances, preferably within the range of 0°C to 15°C. By setting the temperature of the inert gas to 0°C or higher, it is possible to prevent water vapor present inside the chamber 10 from solidifying and adhering to the surface Wa of the substrate W, thereby preventing adverse effects on the substrate W.

[0045] The inert gas is not particularly limited and examples include nitrogen gas, argon gas, helium gas, or air (gas with a nitrogen gas concentration of 80% and an oxygen gas concentration of 20%). The inert gas may also be a mixture of several of these gases. Furthermore, a dry inert gas may be used in which the moisture content of these gases has been reduced to below a certain value. 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 reducing the moisture content of the dry inert gas to 1000 ppm or less, condensation during the freezing process and the sublimation process (details of these processes will be described later) can be prevented.

[0046] The splash-proof cup 11 is positioned to surround the spin base 21. The splash-proof cup 11 is connected to a lifting drive mechanism (not shown) and is capable of moving up and down in the Z direction. When supplying processing liquid or IPA to the pattern-forming surface of the substrate W, the splash-proof cup 11 is positioned by the lifting drive mechanism to a predetermined position as shown in Figure 1, surrounding the substrate W held by the chuck pin 25 from the side. This allows for the collection of processing liquid, IPA, and other liquids that splash from the substrate W or spin base 21.

[0047] The cooling unit 70 is a unit that supplies cooling fluid to the back surface Wb of the substrate W. The cooling unit 70 has the function of freezing the residual processing liquid inside the solidified film by cooling the solidified film through the substrate W. As shown in Figures 1 and 2, the cooling unit 70 comprises at least a cooling fluid storage unit 71, piping 72, a valve 73, and a cooling fluid supply unit 74.

[0048] As shown in Figure 5, the cooling fluid storage unit 71 includes a cooling fluid tank 71a for storing cooling fluid and a cooling fluid temperature adjustment unit 71b for adjusting the temperature of the cooling fluid stored in the cooling fluid tank 71a. Figure 5 is a block diagram showing the schematic configuration of the cooling fluid storage unit 71.

[0049] The cooling fluid temperature control unit 71b is electrically connected to the control unit 30 and adjusts the temperature of the cooling fluid stored in the cooling fluid tank 71a by heating or cooling it according to the operation commands of the control unit 30. The temperature adjustment should be performed so that the cooling fluid stored in the cooling fluid tank 71a is below the freezing point of the residual treatment liquid, preferably within the range of -196°C or higher and -89°C or lower. The cooling fluid temperature control unit 71b is not particularly limited, and known temperature control mechanisms such as a chiller using a Peltier element or piping through temperature-controlled water can be used.

[0050] The cooling fluid reservoir 71 is connected to the cooling fluid supply unit 74 via piping 72, with a valve 73 interposed in the middle of the piping 72. The cooling fluid in the cooling fluid reservoir 71 is pressurized by a pressurizing means (not shown) and sent to the piping 72. The pressurizing means can be achieved by pressurizing with a pump or the like, or by compressing and storing a gas in the cooling fluid reservoir 71; therefore, any pressurizing means may be used.

[0051] Valve 73 is electrically connected to the control unit 30 and is normally closed. The opening and closing of valve 73 is controlled by an operation command from the control unit 30. When valve 73 is opened by an operation command from the control unit 30, the cooling fluid is supplied to the cooling fluid supply unit 74 through the piping 72.

[0052] The cooling fluid supply unit 74 is located below the substrate W, which is supported in a horizontal position by the spin chuck 23. As shown in Figure 2, the cooling fluid supply unit 74 comprises at least an opposing member 74a whose horizontal upper surface is positioned opposite the back surface Wb of the substrate W, a supply pipe 74b attached to the center of the opposing member 74a and extending vertically downward, and a discharge unit 74c that discharges the cooling fluid toward the back surface Wb of the substrate W.

[0053] The opposing member 74a has a disc-shaped outer shape with a smaller area than the substrate W. Furthermore, the opposing member 74a is positioned at an arbitrary distance from the substrate W. The distance between the opposing member 74a and the substrate W is not particularly limited and can be set appropriately to allow sufficient cooling fluid to fill the space.

[0054] The supply pipe 74b is inserted through the center of the hollow rotating shaft 22. The discharge section 74c opens in the supply pipe 74b toward the center Cb of the back surface Wb of the substrate W, and discharges the cooling fluid supplied from the cooling fluid reservoir 71 toward the back surface Wb of the substrate W. The opening area of ​​the discharge section 74c is not particularly limited and can be set appropriately considering the discharge amount, etc. Note that the supply pipe 74b is not connected to the rotating shaft 22, so even if the spin chuck 23 rotates, the discharge section 74c will not rotate.

[0055] Examples of cooling fluids include liquids or gases having a temperature below the freezing point of the residual treatment liquid, preferably between -196°C and -89°C. Examples of liquid cooling fluids include chilled water. Examples of gaseous cooling fluids include gases inert to sublimable materials, more specifically nitrogen gas.

[0056] The control unit 30 is electrically connected to each part of the substrate processing apparatus 1 (see Figures 1, 3-5) and controls the operation of each part. The control unit 30 is composed of a computer having at least an arithmetic processing unit and memory (neither of which are shown). A CPU is used as the arithmetic processing unit to perform various arithmetic operations. The memory includes ROM, which is a read-only memory for storing the substrate processing program, RAM, which is a read-write memory for storing various information, and a magnetic disk for storing control software and data. The magnetic disk has substrate processing conditions (recipes) corresponding to the substrate W pre-stored on it. Substrate processing conditions include, for example, the supply conditions for processing liquid and IPA, the supply conditions for gas, the supply conditions for cooling fluid, and the cooling conditions. The CPU reads the substrate processing conditions into RAM and controls each part of the substrate processing apparatus 1 according to its contents.

[0057] [Processing solution] The processing solution according to this embodiment comprises at least a sublimable substance and a solvent. Preferably, the sublimable substance is dissolved in the solvent in the processing solution. The processing solution plays a function of assisting the drying process for removing liquid present on the surface of the substrate W. In this specification, "sublimable" means that an element, 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 phase, and "sublimable substance" means a substance having such sublimability.

[0058] Examples of sublimable substances include t-butanol, camphor, naphthalene, cyclohexane, cyclohexanol, cyclohexanone oxime, pinacolin oxime, and 4-tert-butylphenol. The solvent is not particularly limited as long as it is soluble in the sublimable substance. Specifically, examples include IPA, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether (PGEE), propylene glycol monomethyl ether (PGME), acetone, benzene, t-butanol, toluene, ethanol, and methanol. Among these solvents, solvents with a high vapor pressure, such as IPA, are preferred in this embodiment.

[0059] [Substrate Processing Method] Next, a substrate processing method using the substrate processing apparatus 1 of this embodiment will be described below with reference to Figures 6 to 9. Figure 6 is a flowchart showing the substrate processing method according to this embodiment. Figures 7 to 9 are schematic diagrams showing the state of the substrate W in each step of Figure 6. A pattern of bumps and depressions Wp is formed on the substrate W by the previous step. The pattern Wp comprises convex portions Wp1 and concave portions Wp2 (see Figures 7 to 9). In this embodiment, the convex portions Wp1 have a height in the range of 100 to 600 nm and a width in the range of 10 to 50 nm. The shortest distance between two adjacent convex portions Wp1 (the shortest width of the concave portion Wp2) is, for example, in the range of 10 to 50 nm. Furthermore, the aspect ratio of the convex portions Wp1, i.e., the value obtained by dividing the height by the width (height / width), is, for example, 10 to 20. In addition, each step is performed under atmospheric pressure unless otherwise specified. Here, "atmospheric pressure" refers to an environment between 0.7 atmospheres and 1.3 atmospheres, centered around standard atmospheric pressure (1 atmosphere, 1013 hPa). In particular, when the substrate processing device 1 is placed in a cleanroom under positive pressure, the environment on the surface Wa of the substrate W will be higher than 1 atmosphere.

[0060] In the substrate processing method of this embodiment, first, a substrate processing program corresponding to a predetermined substrate W is instructed to be executed by the operator. As described above, the substrate W used is one in which a pattern has been formed on its surface Wa in advance. In preparation for loading the substrate W, the substrate processing apparatus 1 performs the following operations according to the operation command of the control unit 30. That is, with the rotation of the chuck rotation mechanism 24 stopped, the chuck pins 25 are positioned to a position suitable for receiving the substrate W. Also, valves 45, 55, 65, and 73 are closed, and nozzles 41, 51, and 61 are positioned in their retracted positions. Furthermore, the chuck pins 25 are opened by an opening / closing mechanism (not shown). Subsequently, the unprocessed substrate W is loaded into the substrate processing apparatus 1 by a substrate loading / unloading mechanism (not shown), placed on the chuck pins 25, and the chuck pins 25 are closed by the opening / closing mechanism to hold the substrate W in the substrate holding section 20.

[0061] After the substrate W is held in the substrate holding section 20, a cleaning process S1 is performed on the substrate W (see Figure 6). In the cleaning process S1 of this embodiment, a cleaning solution is supplied to the surface Wa of the substrate W for cleaning, and then a rinsing process is performed to remove the cleaning solution. That is, a cleaning solution is supplied to the surface Wa of the substrate W, which rotates at a constant speed around axis A1 by an operation command from the control unit 30 to the chuck rotation mechanism 24, using a wet cleaning means (not shown). Subsequently, a rinsing solution is supplied by the wet cleaning means to remove the cleaning solution. Figure 7(a) is a schematic diagram showing the state of the substrate W at the end of the cleaning process S1. As shown in the figure, a liquid film 101 of the rinsing solution is formed on the surface Wa of the substrate W on which the pattern Wp is formed.

[0062] The cleaning solution used in cleaning step S1 is not particularly limited and can be, for example, SC-1 (a liquid containing ammonia, hydrogen peroxide, and water) or SC-2 (a liquid containing hydrochloric acid, hydrogen peroxide, and water). The rinsing solution is also not particularly limited and can be, for example, DIW. The supply amounts of the cleaning solution and rinsing solution are not particularly limited and can be set appropriately according to the area to be cleaned. The cleaning time and rinsing time are also not particularly limited and can be set as needed.

[0063] Next, IPA is supplied to the surface Wa of the substrate W on which the rinse film 101 has been formed (IPA rinsing process S2, see Figure 6). That is, the control unit 30 issues an operation command to the chuck rotation mechanism 24, causing the substrate W to rotate around axis A1 at a constant speed. Next, the control unit 30 issues an operation command to the swivel drive unit 12, positioning the nozzle 51 at the center of the surface Wa of the substrate W. Then, the control unit 30 issues an operation command to the valve 55, opening the valve 55. This supplies IPA from the IPA tank 56 to the surface Wa of the substrate W via the piping 54 and the nozzle 51.

[0064] The IPA supplied to the surface Wa of the substrate W flows from near the center of the surface Wa towards the circumference of the substrate W due to the centrifugal force generated by the rotation of the substrate W, and diffuses over the entire surface Wa of the substrate W. As a result, the liquid film 101 of the rinsing solution on the surface Wa of the substrate W is removed by the supply of IPA, and as shown in Figure 7(b), the entire surface Wa of the substrate W is covered with IPA, forming a liquid IPA film 102. Figure 7(b) is a schematic diagram showing the state of the substrate W at the end of the IPA rinsing process S2. Preferably, the rotation speed of the substrate W is set so that the thickness of the liquid IPA film 102 over the entire surface Wa is greater than the height of the protrusions Wp1. The amount of IPA supplied is not particularly limited and can be set as appropriate.

[0065] After the IPA rinsing process S2 is completed, the control unit 30 issues an operation command to the valve 55 to close the valve 55. The control unit 30 also issues an operation command to the swivel drive unit 12 to position the nozzle 51 in the retracted position.

[0066] Next, a processing solution containing a sublimable substance and a solvent is supplied to the surface Wa of the substrate W on which the IPA liquid film 102 has been formed (supply process S3, see Figure 6). That is, the control unit 30 issues an operation command to the chuck rotation mechanism 24, causing the substrate W to rotate around axis A1 at a constant speed. Subsequently, the control unit 30 issues an operation command to the swivel drive unit 12, positioning the nozzle 41 at the center of the surface Wa of the substrate W. Then, the control unit 30 issues an operation command to the valve 45, opening the valve 45. This supplies the processing solution from the processing solution storage tank 46a to the surface Wa of the substrate W via the piping 44 and the nozzle 41. The processing solution supplied to the surface Wa of the substrate W flows from near the center of the surface Wa of the substrate W toward the periphery of the substrate W due to the centrifugal force generated by the rotation of the substrate W, and diffuses over the entire surface Wa of the substrate W. Here, the rotation speed of the substrate W is preferably set such that the thickness of the liquid film 103 of the processing solution is greater than the height of the protrusions Wp1 over the entire surface Wa. Furthermore, the temperature of the supplied processing solution is preferably set by the temperature control unit 46d to a temperature range that is higher than the freezing point of the processing solution and lower than its boiling point. In addition, although the amount of processing solution supplied is not particularly limited, it is preferably set such that the thickness of the liquid film 103 of the processing solution is greater than the height of the protrusions Wp1 over the entire surface Wa.

[0067] When the processing solution is supplied, the IPA liquid film 102 that had formed on the surface Wa of the substrate W is removed, and as shown in Figure 7(c), the entire surface Wa of the substrate W is covered with the processing solution, forming a processing solution liquid film 103. Figure 7(c) is a schematic diagram showing the state of the substrate W at the end of the supply process S3. Here, the thickness of the processing solution liquid film 103 may be non-uniform, as shown in Figure 7(c). This is due to, for example, the presence of impurities such as Al2O3 or contaminating particles in the processing solution, the viscosity of the processing solution (concentration of sublimable substances), and / or insufficient rotation speed of the substrate W.

[0068] At the end of the supply process S3, the control unit 30 issues an operation command to the valve 45 to close the valve 45. The control unit 30 also issues an operation command to the swivel drive unit 12 to position the nozzle 41 in the retracted position.

[0069] Next, the solvent in the liquid film 103 of the processing solution is evaporated to precipitate the sublimable substance and form a solidified film (solidified film formation step S4, see Figure 6). That is, the control unit 30 issues an operation command to the chuck drive unit, which rotates the substrate W around axis A1. Since 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 rate greater than the evaporation rate of the sublimable substance. Therefore, the solvent begins to evaporate on the surface of the liquid film 103 of the processing solution (see Figure 8(a)). When the sublimable substance in the liquid film 103 of the processing solution becomes supersaturated due to the evaporation of the solvent, the sublimable substance begins to precipitate on the surface of the liquid film 103, and a surface solidified layer 104 is formed. Here, among the precipitated sublimable material particles, the smaller particles shrink and disappear, while the larger particles continue to grow (so-called Oswald growth). As a result, the concentration of the sublimable material inside the liquid film 103 of the processing solution decreases, and the concentration of the sublimable material is no longer supersaturated (see Figure 8(b)). This stops the precipitation of the sublimable material, and as shown in Figure 8(c), a solidified film 106 is formed with residual processing solution 105 remaining inside. Here, the residual processing solution 105 occurs on the pattern Wp side of the substrate W. Furthermore, the residual processing solution 105 is more likely to occur in regions where the film thickness of the liquid film 103 of the processing solution was large due to the presence of impurities, etc. Because the concentration of sublimable material in the residual processing solution 105 is low, it can sometimes be considered a solvent. Figure 8(a) is a schematic diagram showing how a surface solidification layer 104 of the sublimable substance is formed on the surface of the liquid film 103 of the processing liquid; Figure 8(b) is a schematic diagram showing how the concentration of the sublimable substance decreases inside the liquid film 103 of the processing liquid due to Oswald growth of the surface solidification layer 104 of the sublimable substance; and Figure 8(c) is a schematic diagram showing how a solidified film 106 is formed with residual processing liquid 105 remaining inside.

[0070] Next, the cooling unit 70 is used to freeze (solidify) the residual treatment liquid 105 inside the solidified film 106 (freezing (solidification) step S5, see Figure 6). That is, the control unit 30 issues an operation command to the valve 73, which opens the valve 73. As a result, the cooling fluid (for example, cold water at a predetermined temperature) stored in the cooling fluid tank 71a is discharged from the discharge unit 74c towards the back surface Wb of the substrate W via the piping 72 and the supply pipe 74b.

[0071] The cooling fluid supplied to the back surface Wb of the substrate W flows from near the center of the back surface Wb toward the periphery of the substrate W due to the centrifugal force generated by the rotation of the substrate W, and diffuses across the entire back surface Wb of the substrate W. As a result, the entire solidified film 106 formed on the surface Wa of the substrate W is cooled via the substrate W. Here, the temperature of the cooling fluid supplied to the back surface Wb of the substrate W is adjusted by the cooling fluid temperature adjustment unit 71b according to the operation command of the control unit 30, and is kept below the freezing point of the residual treatment liquid 105 remaining inside the solidified film 106. Therefore, the residual treatment liquid 105 freezes, and a frozen body 107 is formed as shown in Figure 9(a). As a result, in this embodiment, the residual treatment liquid 105 remaining inside the solidified film 106 evaporates, and the surface tension of the residual treatment liquid 105 acts on the pattern Wp, preventing the pattern from collapsing. Furthermore, the amount and duration of the cooling fluid supply (cooling time) are not particularly limited, as long as they are sufficient to freeze the residual treatment liquid 105 inside the solidified film 106. Figure 9(a) is a schematic diagram showing how the residual treatment liquid 105 freezes inside the solidified film 106.

[0072] Next, gas is supplied to the surface Wa of the substrate W on which the solidified film 106 is formed, and the solidified film 106 and the frozen body 107 are sublimated and removed from the surface Wa of the substrate W (sublimation step S6, see Figure 6). In sublimation step S6, the cooling fluid is continuously supplied to the back surface Wb of the substrate W by the cooling unit 70. This allows the solidified film 106 to be continuously cooled at a temperature below the freezing point of the residual treatment liquid 105, preventing the frozen body 107 from melting.

[0073] In the sublimation process S6, the control unit 30 first issues an operation command to the chuck rotation mechanism 24, causing the substrate W to rotate around axis A1 at a constant speed. The rotation speed of the substrate W is set to a speed at which gas (for example, nitrogen gas) is sufficiently supplied to the peripheral edge of the substrate W by the rotation of the substrate W.

[0074] Next, the control unit 30 issues an operation command to the swivel drive unit 12, positioning the nozzle 61 at the center of the substrate W's surface Wa. Then, the control unit 30 issues an operation command to the valve 65, opening the valve 65. This supplies gas from the gas tank 66a to the substrate W's surface Wa via the piping 64 and nozzle 61.

[0075] Here, the temperature of the gas, such as nitrogen gas, supplied to the solidification film 106 is adjusted by the gas temperature adjustment unit 66b according to the operation command of the control unit 30. Furthermore, the partial pressure of the vapor of the sublimable substance in the gas, such as nitrogen gas, is set lower than the saturated vapor pressure of the sublimable substance at the gas supply temperature. Therefore, when such a gas is supplied to the surface Wa of the substrate W and comes into contact with the solidification film 106, the sublimable substance sublimes from the solidification film 106 into the gas. In addition, since the gas, such as nitrogen gas, is at a lower temperature than the melting point of the sublimable substance, the solidification film 106 can be sublimated while preventing the solidification film 106 from melting. As a result, the solidification film 106 is removed from the surface Wa of the substrate W, as shown in Figure 9(b). Figure 9(b) is a schematic diagram showing the state after the solidification film 106 has been removed from the surface Wa of the substrate W.

[0076] Furthermore, in the sublimation process S6, the frozen body 107 that had formed inside the solidified film 106 is also removed. That is, even after the solidified film 106 has been removed by sublimation, the cooling unit 70 continues to supply cooling fluid and nitrogen gas to the back surface Wb of the substrate W. This prevents the frozen body 107 from melting (or thawing) while sublimating the frozen body 107, and removes the frozen body 107 from the surface Wa of the substrate W, as shown in Figure 9(c). Figure 9(c) is a schematic diagram showing the state after the frozen body 107 has been removed from the surface Wa of the substrate W.

[0077] Thus, in the sublimation process S6, the sublimation of the solidified film 106 and the frozen body 107 prevents surface tension from acting on the pattern Wp when removing substances such as IPA present on the surface Wa of the substrate W, thereby suppressing the occurrence of pattern collapse and allowing the surface Wa of the substrate W to be dried well.

[0078] After the sublimation process S6 is completed, the control unit 30 issues an operation command to the valve 65 to close the valve 65. The control unit 30 also issues an operation command to the swivel drive unit 12 to position the nozzle 61 in the retracted position.

[0079] This completes the series of substrate drying processes. After the substrate drying process described above, the dried substrate W is removed from the chamber 10 by a substrate loading / unloading mechanism (not shown).

[0080] As described above, in this embodiment, the residual treatment liquid 105 remaining inside the solidified film 106 is frozen, and furthermore, the frozen body 107 of the residual treatment liquid 105 is sublimated together with the solidified film 106 and removed from the surface Wa of the substrate W. In other words, in this embodiment, in order to prevent the residual treatment liquid 105 present inside the solidified film 106 from evaporating, the residual treatment liquid 105 does not exert surface tension on the pattern Wp during such evaporation. As a result, the substrate processing method of this embodiment can perform substrate processing well while suppressing or preventing the collapse of the pattern Wp.

[0081] (Second Embodiment) A second embodiment of the present invention will be described below. This embodiment differs from the first embodiment in that, in the freezing step S5, cooling is performed by a cooling plate instead of cooling by supplying a cooling fluid. Even with this configuration, the pattern formation surface of the substrate W can be processed well while suppressing pattern collapse.

[0082] [Substrate processing equipment] A substrate processing apparatus according to the second embodiment will be described with reference to Figures 1 and 10. Figure 10 is a schematic cross-sectional view showing the substrate holding section and the substrate contact cooling section in the substrate processing apparatus.

[0083] The substrate processing apparatus according to this embodiment has basically the same configuration as the substrate processing apparatus 1 according to the first embodiment, except that it is equipped with a substrate contact cooling unit 80 instead of a cooling unit 70 (see Figure 10). Therefore, components having the same function are given the same reference numerals and their detailed descriptions are omitted.

[0084] The substrate contact cooling unit 80 is a unit that cools the back surface Wb of the substrate W. The substrate contact cooling unit 80 has the function of freezing the residual processing liquid inside the solidified film by cooling the back surface Wb of the substrate W. As shown in Figure 10, the substrate contact cooling unit 80 comprises at least a cooling plate 81 and a lifting shaft 82 connected to the lower surface of the cooling plate 81 for raising and lowering the cooling plate 81.

[0085] The cooling plate 81 may be formed in the shape of a disc, for example. The size (diameter) of the cooling plate 81 is slightly smaller than that of the substrate W. The cooling plate 81 can be made of a metal such as aluminum, silver, or copper. Inside the cooling plate 81, there is a cooling fluid channel 83 through which a cooling fluid flows. As the cooling fluid flows through the cooling fluid channel 83, the substrate W in contact with the cooling plate 81 can be cooled from the back surface Wb side. This cools the solidified film provided on the surface Wa of the substrate W via the substrate W, and freezes the residual treatment liquid inside the solidified film. The cooling fluid can be the same as that described in the first embodiment. The cooling fluid is also temperature-controlled by a cooling fluid temperature control unit (not shown) so that it is below the freezing point of the residual treatment liquid. A specific example of the cooling fluid temperature control unit can be the one described in the first embodiment.

[0086] The cooling fluid passage 83 is connected to a cooling fluid supply pipe 84 that supplies cooling fluid to the cooling fluid passage 83, and a cooling fluid discharge pipe 86 that discharges cooling fluid from the cooling fluid passage 83. A valve 85 is also inserted along the path of the cooling fluid supply pipe 84.

[0087] Valve 85 is electrically connected to the control unit 30 and is normally closed. The opening and closing of valve 85 is controlled by an operation command from the control unit 30. When valve 85 is opened by an operation command from the control unit 30, the cooling fluid is supplied to the cooling fluid passage 83 through the cooling fluid supply pipe 84 and then discharged from the cooling fluid discharge pipe 86.

[0088] A lifting mechanism (not shown) including an actuator such as a motor is connected to the lifting shaft 82. The cooling plate 81 is raised and lowered by the lifting mechanism between a contact position in contact with the back surface Wb of the substrate W and a separated position spaced away from the bottom surface of the substrate W. The lifting mechanism includes an actuator such as an electric motor.

[0089] [Processing solution and substrate processing method] Next, a substrate processing method according to the second embodiment, using the substrate processing apparatus of the second embodiment, will be described. Note that the processing solution is the same as the processing solution described in the first embodiment, so its description will be omitted.

[0090] The substrate processing steps will be described below with reference to Figures 1, 6, and 10 as appropriate. In the second embodiment, the cleaning step S1, IPA rinsing step S2, supply step S3, and solidification film formation step S4 shown in Figure 6 are the same as in the first embodiment, so their descriptions will be omitted.

[0091] After the cleaning process S1, IPA rinsing process S2, supply process S3, and solidification film formation process S4 are performed sequentially, a freezing process S5' is carried out as shown in Figure 6. In this embodiment, the freezing process S5' is performed using a substrate contact cooling unit 80. Specifically, the control unit 30 issues an operation command to the lifting mechanism to raise the cooling plate 81 to a contact position where it contacts the back surface Wb of the substrate W, and the cooling plate 81 comes into contact with the back surface Wb of the substrate W. Subsequently, the control unit 30 issues an operation command to the valve 85, which opens the valve 85. As a result, the cooling fluid (for example, cold water at a predetermined temperature) flows through the cooling fluid supply pipe 84 and through the cooling fluid passage 83 provided inside the cooling plate 81, cooling the substrate W from its back surface Wb side. Here, the temperature of the cooling fluid flowing through the cooling fluid channel 83 is adjusted to be below the freezing point of the residual treatment liquid 105 remaining inside the solidified film 106, so that the residual treatment liquid 105 freezes and becomes a frozen body 107 (see Figure 9(a)). As a result, even in this embodiment, the residual treatment liquid 105 remaining inside the solidified film 106 does not evaporate, and the surface tension of the residual treatment liquid 105 acts on the pattern Wp, preventing the pattern from collapsing. The cooling fluid flowing through the cooling fluid channel 83 is discharged to the outside of the substrate processing apparatus via the cooling fluid discharge pipe 86 after the substrate W has cooled. Furthermore, the amount of cooling fluid supplied and the supply time (cooling time) are not particularly limited, and only need to be sufficient to freeze the residual treatment liquid 105 inside the solidified film 106.

[0092] Next, gas is supplied to the surface Wa of the substrate W on which the solidified film 106 has been formed, and the solidified film 106 and frozen body 107 are sublimated and removed from the surface Wa of the substrate W (sublimation step S6', see Figure 6). That is, the control unit 30 issues an operation command to the lifting mechanism, lowering the cooling plate 81 to the retracted position and separating it from the back surface Wb of the substrate W. Subsequently, the control unit 30 issues an operation command to the chuck rotation mechanism 24, rotating the substrate W around axis A1 at a constant speed. The rotation speed of the substrate W is set to a speed at which sufficient gas is supplied to the peripheral edge of the substrate W by the rotation of the substrate W. Subsequently, the control unit 30 issues an operation command to the swivel drive unit 12, positioning the nozzle 61 at the center of the surface Wa of the substrate W. Then, the control unit 30 issues an operation command to the valve 65, opening the valve 65. This supplies gas from the gas tank 66a to the surface Wa of the substrate W via the piping 64 and the nozzle 61. This causes the solidified film 106 and the frozen body 107 to sublimate and be removed from the surface Wa of the substrate W.

[0093] After the sublimation process S6' is completed, the control unit 30 issues an operation command to the valves 65 and 85 to close them. The control unit 30 also issues an operation command to the swivel drive unit 12 to position the nozzle 61 in the retracted position.

[0094] As described above, in this embodiment, the cooling plate 81 is used to freeze the residual treatment liquid 105 remaining inside the solidified film 106, and further sublimation of the frozen residual treatment liquid 105 107 together with the solidified film 106 is performed to remove it from the surface Wa of the substrate W. In other words, in this embodiment as well, in order to prevent the residual treatment liquid 105 from evaporating, the residual treatment liquid 105 does not exert surface tension on the pattern Wp during such evaporation. As a result, the substrate processing method of this embodiment can also perform substrate processing well while suppressing or preventing the collapse of the pattern Wp.

[0095] (Other matters) The above description has described the most preferred embodiments of the present invention. However, the present invention is not limited to these embodiments, and various modifications are possible within substantially the same scope as the technical idea described in the claims of the present invention.

[0096] For example, in the first embodiment, the case in which the cooling unit 70 is used in the freezing step S5 as a means of freezing the residual treatment liquid inside the solidified film was described as an example. However, the present invention is not limited to this embodiment. For example, the freezing step S5 may be performed using the gas supply unit 60 in combination with the cooling unit 70, or using only the gas supply unit 60. In this case, the gas supplied by the gas supply unit 60 is temperature-adjusted by the gas temperature adjustment unit 66b according to the operation command of the control unit 30 so that it is below the freezing point of the residual treatment liquid 105. As a result, the gas can be made to function as a cooling gas. Note that when the freezing step S5 is performed using only the gas supply unit 60, the cooling unit 70 may be omitted from the substrate processing apparatus 1.

[0097] Furthermore, in the second embodiment, the case in which the substrate contact cooling unit 80 is used in the freezing step S5 as a means of freezing the residual treatment liquid inside the solidified film was described as an example. However, the present invention is not limited to this embodiment. For example, the freezing step S5 may be performed using the gas supply unit 60 in combination with the substrate contact cooling unit 80. In this case as well, the gas supplied by the gas supply unit 60 is temperature-adjusted by the gas temperature adjustment unit 66b according to the operation command of the control unit 30 so that it is below the freezing point of the residual treatment liquid 105. As a result, the gas can be made to function as a cooling gas.

[0098] Furthermore, in the first and second embodiments, the case in which the freezing step S5 (S5') is performed after the solidification film formation step S4 has been completed has been described. However, the present invention is not limited to these embodiments. For example, the freezing step S5 (S5') may be started after the start of the solidification film formation step S4 and may be performed in parallel with the solidification film formation step S4. As described above, the solidification film 106 is formed from the surface layer of the liquid film as sublimable substances precipitate due to the evaporation of the solvent. Therefore, the residual treatment liquid inside the solidification film 106 can also be frozen by performing the freezing step S5 (S5') in parallel with the growth of the surface solidification layer 104. [Industrial applicability]

[0099] The present invention can be applied to drying techniques for removing liquid adhering to the pattern-forming surface of a substrate, and to substrate processing techniques in general that use said drying techniques to process the surface of a substrate. [Explanation of Symbols]

[0100] 1: Substrate processing device, 20: Substrate holding unit, 30: Control unit, 40: Processing liquid supply unit, 46: Processing liquid storage unit, 50: IPA supply unit, 60: Gas supply unit, 70: Cooling unit, 71: Cooling fluid storage unit, 72: Piping, 73: Valve, 74: Cooling fluid supply unit, 74a: Opposing member, 74b: Supply pipe, 74c: Discharge unit, 80: Cooling unit for substrate contact, 81: Cooling plate, 81a: Cooling fluid tank, 81b: Cooling fluid temperature adjustment unit, 82: Lifting shaft , 83: Cooling fluid channel, 84: Cooling fluid supply pipe, 85: Valve, 86: Cooling fluid discharge pipe, 103: Liquid film of processing liquid, 104: Surface solidification layer, 105: Processing liquid, 106: Solidification film, 107: Frozen body, S1: Washing process, S2: IPA rinsing process, S3: Supply process, S4: Solidification film formation process, S5, S5': Freezing process, S6, S6': Sublimation process, W: Substrate, Wa: Surface, Wb: Back surface, Wp: Pattern, Wp1: Convex part, Wp2: Recess

Claims

1. A substrate processing method for processing the pattern formation surface of a substrate, A supply step of supplying a processing solution containing a sublimable substance and a solvent to the pattern forming surface, A solidification film formation step involves evaporating the solvent from the liquid film of the processing liquid supplied to the pattern forming surface to precipitate the sublimable substance and form a solidified film, A freezing step in which residual treatment liquid remaining inside during or after the formation of the solidified film in the solidified film formation step is frozen, A sublimation step is performed to remove the solidified film and the frozen residual treatment liquid from the pattern-forming surface by sublimation. A substrate processing method, including the following.

2. A substrate processing method according to claim 1, A substrate processing method, wherein the freezing step is a step of cooling the solidified film to a temperature at least below the freezing point of the residual processing liquid.

3. A substrate processing method according to claim 1, A substrate processing method, wherein the freezing step is a step of cooling the solidified film and freezing the residual processing liquid by supplying the solidified film with a cooling gas that is at least inert to the sublimable substance.

4. A substrate processing method according to claim 1, A substrate processing method, wherein the freezing step is a step of supplying a cooling fluid to the surface of the substrate opposite to the pattern-forming surface, thereby cooling the solidified film through the substrate and freezing the residual processing liquid.

5. A substrate processing method according to claim 1, A substrate processing method, wherein the freezing step is a step of cooling the solidified film through the substrate by bringing a cooling plate into contact with the surface of the substrate opposite to the pattern-forming surface, thereby freezing the residual processing liquid.

6. A substrate processing method according to claim 1, The aforementioned sublimation process is By supplying the cooling fluid to the side of the substrate opposite to the pattern-forming surface, the solidified film is cooled through the substrate, A substrate processing method comprising the step of supplying a gas that is at least inert to the sublimable material toward the pattern-forming surface at a temperature below the freezing point of the sublimable material.

Images