Substrate processing method and substrate processing apparatus

Abstract

To provide a substrate processing method and a substrate processing apparatus, which, when forming a solidified film of a processing liquid in performing sublimation drying of a substrate surface by batch processing, can reduce or prevent the occurrence of pattern collapse by minimizing the effect of surface tension of the processing liquid on the pattern.SOLUTION: A substrate processing method to collectively process a group of substrates W, each substrate having a pattern formation surface on a surface thereof, includes: an immersion step S2 of collectively immersing the group of substrates W into a processing liquid that is stored in a processing tank 12 and that contains a sublimable substance and a solvent; and a solidified film formation step S3 of forming a solidified film containing the sublimable substance on a pattern formation surface while collectively lifting up the group of substrates W from the processing liquid in a standing posture. In the solidified film formation step S3, a time when the sublimable substance is precipitated by the evaporation of the solvent and the processing liquid is solidified on the pattern formation surface of a lifted-up substrate W is shorter than a collapse time required until a pattern collapse on the pattern formation surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a substrate processing method and a substrate processing apparatus capable of collectively performing sublimation drying on a plurality of substrates on which a stack such as a three-dimensional NAND structure is formed, by batch processing. [Background technology]

[0002] In the manufacturing process of a semiconductor device, a processing liquid is supplied to a substrate surface in the process of wet etching or surface cleaning, and then a process of drying the substrate surface is performed. However, for example, when a pattern with a large aspect ratio is formed on the substrate surface, there is a concern that the Laplace pressure of the processing liquid acts on the pattern when the processing liquid is dried, causing the pattern to collapse. In recent years, with the development of next-generation devices using miniaturization and new materials, a technology is required to suppress the collapse of a pattern formed on a substrate surface. Here, a sublimation drying technology that solidifies a processing liquid to form a solidified film and further sublimates and removes the solidified film can prevent or reduce the Laplace pressure derived from the processing liquid from acting on the pattern. Therefore, this technology is considered promising as a technology that can suppress the collapse of a pattern.

[0003] Sublimation drying technology in substrate processing is being established in the single-wafer processing in which substrates are processed one by one (for example, Patent Document 1 below). However, sufficient sublimation drying technology has not been established in the batch processing in which multiple substrates are processed at once. For example, in a 3D NAND structure such as a 3D NAND flash memory, a batch phosphoric acid treatment is required, but if the sublimation drying technology is not used, there is a concern that the pattern will collapse. Therefore, there is a demand for the establishment of a batch sublimation drying technology. However, when the sublimation drying of the substrate surface is performed in the batch process, there is a problem that the surface tension of the processing liquid acts on the pattern during the formation of a solidified film on the substrate surface, causing the pattern to collapse. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-70873 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a substrate processing method and substrate processing apparatus which, when performing sublimation drying of a substrate surface in a batch manner, can reduce or prevent the occurrence of pattern collapse by minimizing the effect of the surface tension of the processing liquid on a pattern when a solidified film of the processing liquid is formed. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the substrate processing method according to the present invention is a substrate processing method for collectively processing a plurality of substrates having a pattern-formed surface thereon, comprising: an immersion step of immersing the plurality of substrates collectively in a processing liquid stored in a processing tank and containing a sublimable substance and a solvent; and a solidified film formation step of evaporating the solvent while collectively pulling the plurality of substrates upright from the processing liquid to precipitate the sublimable substance and form a solidified film containing the sublimable substance on the surfaces of the substrates, wherein the time required for the sublimable substance to be precipitated by evaporation of the solvent to form the solidified film in the solidified film formation step is shorter than the collapse time required for the pattern on the pattern-formed surface to collapse.

[0007] In the above-mentioned configuration, by immersing a plurality of substrates in the processing liquid at once, for example, liquid adhering to the substrate surface can be replaced with the processing liquid (immersion process). Next, the plurality of substrates are lifted up in an upright position from the processing liquid at once, and during this lifting, the solvent in the processing liquid is evaporated to precipitate a sublimable substance, thereby forming a solidified film on the surface of each substrate (solidified film forming process). Here, when forming a solidified film on the surface of each substrate, there is a problem that the surface tension of the processing liquid acts on the pattern on the pattern forming surface, causing the pattern to collapse. However, in the above-mentioned configuration, when the substrate is lifted up, the time during which the solvent evaporates to cause the sublimable substance to precipitate and form a solidified film is set to be shorter than the time during which the surface tension of the processing liquid acts on the pattern and causes the pattern to collapse. As a result, in the above-mentioned configuration, a solidified film can be formed while solidifying the processing liquid before the pattern collapses due to the surface tension of the processing liquid. As a result, the occurrence of pattern collapse can be reduced or prevented compared to the conventional substrate processing method.

[0008] In the above configuration, it is preferable that the method further includes a heating step of heating the processing liquid before the processing liquid is stored in the processing tank, the immersion step is performed while immersing the plurality of substrates collectively in the processing liquid heated in the heating step, thereby heating the plurality of substrates collectively, and the solidified film formation step is performed while generating a Marangoni flow in which the processing liquid on the surfaces of the substrates flows toward the processing liquid stored in the processing tank when the plurality of heated substrates are pulled up collectively in an upright position.

[0009] According to the above-mentioned configuration, the processing liquid stored in the processing tank is preheated in the heating step, so that the multiple substrates can be immersed in the processing liquid at the same time, and the multiple substrates can be heated at the same time. Furthermore, in the solidified film forming step, the heated multiple substrates are lifted from the processing liquid, so that the temperature at the meniscus where the processing liquid contacts the substrate surface can be increased. On the other hand, the liquid surface of the processing liquid stored in the processing tank is in contact with the outside air, and therefore has a low temperature. Therefore, the surface tension at the meniscus becomes smaller than the surface tension at the liquid surface, and the processing liquid on the substrate surface flows so as to be drawn toward the liquid surface, so-called Marangoni flow can be generated. This allows the processing liquid to be well drained on the surface of the lifted substrate, and the solidified film can be formed on the pattern formation surface in a shorter time. As a result, the occurrence of pattern collapse can be further reduced or prevented.

[0010] Furthermore, in the above-mentioned configuration, it is preferable that the solvent in the processing liquid has a vapor pressure of 500 Pa or more and 90 kPa or less at 20° C. By using a solvent contained in the processing liquid having a vapor pressure of 500 Pa or more at 20° C., it is possible to promote evaporation of the solvent in the processing liquid on the pattern formation surface when multiple substrates are lifted up in an upright position at the same time in the solidified film formation step. This makes it possible to form a solidified film before the surface tension of the processing liquid acts to cause the pattern to collapse.

[0011] In the above configuration, the heating step preferably heats the processing liquid before being stored in the processing tank to a temperature range above room temperature and below the boiling point of the processing liquid. By previously heating the processing liquid to a temperature higher than room temperature in the heating step, it is possible to improve the generation of Marangoni flows when the substrate is pulled up from the processing liquid in the solidified film forming step. On the other hand, by heating the processing liquid to a temperature below the boiling point of the processing liquid in the heating step, it is possible to prevent a change in the composition of the processing liquid due to evaporation of the solvent.

[0012] In the above configuration, the outer surface of the treatment tank is preferably covered with a heat insulating material, and the immersion step and the solidified film formation step are preferably performed while maintaining the temperature of the treatment liquid heated in the heating step. By covering the outer surface of the treatment tank with a heat insulating material, it is possible to prevent a change in temperature of the treatment liquid in the treatment tank due to heat exchange with the outside air on the outer surface. As a result, the temperature of the treatment liquid stored in the treatment tank can be maintained, and the substrate can be well heated in the immersion step. Furthermore, in the solidified film formation step, a Marangoni flow can be well generated when the substrate is pulled up from the treatment liquid.

[0013] In order to solve the above-mentioned problems, the substrate processing apparatus of the present invention is a substrate processing apparatus for collectively processing a plurality of substrates having a pattern formation surface on a surface thereof, the substrate processing apparatus comprising: a processing liquid storage section for storing a processing liquid containing a sublimable substance and a solvent; a heating section for heating the processing liquid stored in the processing liquid storage section; a processing tank for storing the processing liquid heated by the heating section and supplied from the processing liquid storage section; a holding section for collectively holding the plurality of substrates in an upright position; a lifting mechanism for raising and lowering the holding section relative to the processing tank to immerse the plurality of substrates held by the holding section in the processing liquid collectively or to remove the plurality of substrates held by the holding section from the processing liquid collectively; and a control unit that controls the lifting mechanism, and the immersion and removal are performed to evaporate the solvent while lifting up the plurality of substrates immersed in the treatment liquid at the same time, thereby precipitating the sublimable substance and forming a solidified film containing the sublimable substance on the surfaces of the substrates, and the control unit controls the lifting mechanism to adjust the immersion time of the plurality of substrates in the treatment liquid, thereby heating the plurality of substrates at the same time in the treatment liquid heated by the heating unit, and further, when controlling the lifting mechanism to lift up the plurality of heated substrates at the same time in an upright position, a Marangoni flow is generated in which the treatment liquid on the surfaces of the substrates flows toward the treatment liquid stored in the treatment tank.

[0014] According to the above-mentioned configuration, the processing tank stores the processing liquid stored in the processing liquid storage unit and heated by the heating unit. The holding unit can hold the plurality of substrates in an upright position, and the lifting mechanism controlled by the control unit can raise and lower the holding unit holding the plurality of substrates relative to the processing tank. Therefore, in the above-mentioned configuration, the plurality of substrates are immersed in the processing liquid all at once, and then lifted up from the processing liquid all at once in an upright position, so that during the lifting up, a solidified film can be formed on the surface of each substrate while evaporating the solvent and precipitating a sublimable substance.

[0015] Here, since the processing liquid stored in the processing tank is preheated by the heating unit, the substrates can be immersed in the processing liquid while adjusting the immersion time, and thus the substrates can be heated all at once. As a result, when the control unit controls the lifting mechanism to lift the heated substrates all at once from the processing liquid, the temperature of the processing liquid can be increased at the meniscus portion where the processing liquid contacts the surface of each substrate. On the other hand, the liquid surface portion of the processing liquid stored in the processing tank is in contact with the outside air, and therefore has a low temperature. Therefore, the surface tension at the meniscus portion is smaller than the surface tension at the liquid surface, and the processing liquid on the substrate surface flows so as to be drawn toward the liquid surface side, which is called a Marangoni flow, can be generated. This allows the processing liquid to be well drained on the surface of the substrate being lifted, and the solidified film can be formed on the pattern formation surface in an even shorter time. As a result, the occurrence of pattern collapse can be further reduced or prevented.

[0016] Furthermore, in the above-mentioned configuration, it is preferable that the solvent in the processing liquid has a vapor pressure of 500 Pa or more and 90 kPa or less at 20° C. By using a solvent contained in the processing liquid having a vapor pressure of 500 Pa or more at 20° C., it is possible to promote evaporation of the solvent in the processing liquid on the pattern formation surface when the lifting mechanism lifts up multiple substrates in an upright position all at once. This makes it possible to form a solidified film before the surface tension of the processing liquid acts to collapse the pattern. As a result, it is possible to form a solidified film while preventing or reducing the collapse of the pattern.

[0017] In the above configuration, the heating unit preferably heats the processing liquid stored in the processing liquid storage unit to a temperature above room temperature and below the boiling point of the processing liquid. By heating the processing liquid in advance to a temperature higher than room temperature by the heating unit, it is possible to improve the generation of Marangoni flow when the lifting mechanism lifts the substrate from the processing liquid. On the other hand, by heating the processing liquid by the heating unit to a temperature below the boiling point of the processing liquid, it is possible to prevent a change in the composition of the processing liquid due to evaporation of the solvent.

[0018] In the above configuration, it is preferable that the outer surface of the treatment tank is covered with a heat insulating material, and the temperature of the treatment liquid heated by the heating unit is maintained. By covering the outer surface of the treatment tank with a heat insulating material, it is possible to prevent a change in temperature of the treatment liquid in the treatment tank due to heat exchange with the outside air at the outer surface. As a result, the temperature of the treatment liquid stored in the treatment tank is maintained, and the substrate can be well heated when immersed in the treatment liquid. Furthermore, when the lifting mechanism lifts the substrate from the treatment liquid, a Marangoni flow can be well generated. Effect of the Invention

[0019] According to the present invention, the solidified film is formed by immersing a plurality of substrates in a processing liquid containing a sublimable substance and a solvent, and then lifting the substrates in an upright position from the processing liquid at the same time, while evaporating the solvent and precipitating the sublimable substance. In addition, in the formation of the solidified film, the time required for the solidified film to be formed is shorter than the time required for the pattern to collapse due to the action of the surface tension of the processing liquid. Therefore, the present invention can form the solidified film before the pattern collapses. That is, the present invention can form the solidified film on a plurality of substrates at the same time by batch processing while reducing or preventing the occurrence of pattern collapse, thereby improving the throughput compared to conventional substrate processing. [Brief description of the drawings]

[0020] [Figure 1]FIG. 1(a) is an explanatory diagram showing the state before multiple substrates are immersed in a processing liquid or after they have been pulled out of a processing liquid in a substrate processing apparatus according to an embodiment of the present invention, and FIG. 1(b) is an explanatory diagram showing the state in which multiple substrates are immersed in the processing liquid. [Diagram 2] 2 is a block diagram showing a schematic configuration of a processing liquid supply unit in the substrate processing apparatus according to the embodiment of the present invention. FIG. [Diagram 3] 2 is a cross-sectional view illustrating an outline of a processing tank of a solidified film forming unit in the substrate processing apparatus according to an embodiment of the present invention. FIG. [Figure 4] 1 is a side view showing a schematic configuration of a holding unit and a lifting mechanism in a substrate processing apparatus according to an embodiment of the present invention. [Diagram 5] FIG. 2 is an explanatory diagram showing a schematic configuration of a control unit in the substrate processing apparatus according to an embodiment of the present invention. [Figure 6] 5A to 5C are explanatory views that diagrammatically show how a solidified film is formed on the surface of a substrate that has been pulled up from a processing liquid in a substrate processing method according to an embodiment of the present invention; [Figure 7] 2 is a flowchart showing an example of an overall flow of a substrate processing method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] (Substrate processing equipment) First, a substrate processing apparatus according to the present embodiment will be described below with reference to the drawings. The substrate processing apparatus according to the present embodiment is a batch-type substrate processing apparatus used for drying processing after cleaning processing, and can be used for processing various substrates, for example. Here, 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. The substrate processing apparatus according to the present embodiment is suitable for processing substrates having three-dimensional structures such as a three-dimensional NAND structure formed on the surface, for example.

[0022] 1(a) and 1(b), the substrate processing apparatus 1 of this embodiment specifically includes at least a solidified film forming section 10, a holding section (lifter) 20, a lifting mechanism 23, a processing liquid temperature measuring section 40, and a control unit 30 that controls each section of the substrate processing apparatus 1. Fig. 1(a) is an explanatory diagram showing a state before a plurality of substrates W are immersed in a processing liquid or after they are lifted up from the processing liquid in the substrate processing apparatus 1 of this embodiment, and Fig. 1(b) is an explanatory diagram showing a state in which a plurality of substrates W are immersed in the processing liquid.

[0023] The solidified film forming unit 10 is a batch processing unit that collectively forms a solidified film containing a sublimable substance on the surfaces of multiple substrates W (hereinafter sometimes referred to as a "group of substrates W"). The solidified film is formed while drying the solvent of the processing liquid when the group of substrates W immersed in the processing liquid is removed from the processing liquid (details will be described later). The solidified film forming unit 10 includes a processing liquid supply unit 11 and a processing tank 12.

[0024] The processing liquid supply unit 11 can supply a processing liquid to the processing tank 12. Specifically, as shown in Fig. 2, the processing liquid supply unit 11 at least includes a processing liquid storage unit 111, a heating unit 112, a pressurizing unit 113, a pipe 114, and a valve 115. Fig. 2 is a block diagram showing a schematic configuration of the processing liquid supply unit 11.

[0025] The treatment liquid storage section 111 can store the treatment liquid. The treatment liquid storage section 111 may be provided with an agitation section for agitating the treatment liquid stored therein. The agitation section is not particularly limited, and a known agitation section, such as one equipped with a propeller-shaped agitation blade or a circulation pump, can be used. When the agitation section is provided, the agitation section is electrically connected to the control unit 30. This allows the agitation section to agitate the treatment liquid in the treatment liquid storage section 111 based on an operation command from a control section (details of which will be described later) in the control unit 30. By agitating the treatment liquid, the concentration of the sublimable substance and the temperature of the treatment liquid can be made uniform.

[0026] The processing liquid includes at least a sublimable substance and a solvent. The sublimable substance is preferably dissolved in the solvent in the processing liquid. The processing liquid serves to assist the drying process in the drying process for removing the liquid present on the surface of the substrate W. In this specification, "sublimability" means that a single substance, compound, or mixture has a property of undergoing phase transition from solid to gas or gas to solid without passing through a liquid state, and "sublimable substance" means a substance having such sublimability.

[0027] Sublimable substances include t-butanol, camphor, naphthalene, cyclohexane, cyclohexanol, cyclohexanone oxime, pinacoline oxime, and 4-tert-butylphenol.

[0028] The solvent is not particularly limited as long as it dissolves the sublimable substance, but it is preferable that the vapor pressure at 20°C is 500 Pa or more and 90 kPa or less (preferably 2000 Pa or more and 65 kPa or less, more preferably 4000 Pa or more and 30 kPa or less). By using a solvent with a vapor pressure of 500 Pa or more at 20°C, it is possible to promote evaporation of the solvent in the processing liquid on the pattern formation surface when the group of substrates W is pulled up together in an upright position (details will be described later). As a result, it is possible to form a solidified film before the surface tension of the processing liquid acts to cause the pattern to collapse.

[0029] More specifically, examples of the solvent include isopropyl alcohol (IPA), propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether (PGEE), propylene glycol monomethyl ether (PGME), acetone, benzene, t-butanol, toluene, ethanol, methanol, etc. Among these solvents, in this embodiment, a solvent having a high vapor pressure such as IPA is preferable.

[0030] The concentration of the sublimable substance in the treatment liquid can be appropriately set according to need. The concentration of the sublimable substance is usually 0.2 mass% or more and 40 mass% or less, preferably 0.4 mass% or more and 11.4 mass% or less, more preferably 0.6 mass% or more and 4 mass% or less, based on the total mass of the treatment liquid.

[0031] The heating unit 112 heats the treatment liquid in the treatment liquid storage unit 111 to adjust the temperature. The lower limit of the temperature of the treatment liquid after the temperature adjustment is preferably higher than room temperature. On the other hand, the upper limit of the temperature of the treatment liquid after the temperature adjustment is preferably a temperature lower than the boiling point of the treatment liquid. When the precipitation temperature at which the sublimable substance starts to precipitate in the treatment liquid is higher than room temperature, it is preferable that the temperature of the treatment liquid after the temperature adjustment is higher than the precipitation temperature. This makes it possible to suppress changes in the concentration of the treatment liquid. In this specification, "room temperature" means a temperature range of 5°C to 35°C.

[0032] The heating part 112 is electrically connected to the control unit 30, and adjusts the temperature of the treatment liquid based on an operation command from a control part in the control unit 30. Specifically, the heating part 112 may be a known temperature adjustment mechanism, such as a resistance heater, a Peltier element, or a pipe through which temperature-adjusted water flows.

[0033] The pressurizing unit 113 pressurizes the inside of the processing liquid storage unit 111, thereby pressure-feeding the heated processing liquid stored in the processing liquid storage unit 111 to the processing tank 12. The pressurizing unit 113 may, for example, include a gas tank for storing gas, a pump for pressurizing the gas, and a pipe for supplying the gas to the processing liquid storage unit 111. The gas tank is connected to the processing liquid storage unit 111 via the pipe. A pump is also inserted in the pipe. The pump is electrically connected to the control unit 30, and can supply the gas stored in the gas tank to the processing liquid storage unit 111 via the pipe in response to an operation command from the control unit in the control unit 30. This makes it possible to adjust the pressure in the processing liquid storage unit 111, and to pressure-feed the heated processing liquid to the processing tank 12. It is preferable to use an inert gas, such as nitrogen gas, that is not active against the processing liquid as the gas. In addition, since the heated processing liquid in the processing liquid storage section 111 is pressure-fed using gas pressure, the processing liquid storage section 111 is preferably configured to be highly airtight.

[0034] One end of the pipe 114 is connected to the treatment liquid storage section 111. The other end of the pipe 114 is connected to the injection pipe 13 of the treatment tank 12 (see FIGS. 1(a) and 1(b)).

[0035] The valve 115 is provided midway along the path of the piping 114. The valve 115 is electrically connected to the control unit 30 and is usually closed. The opening and closing of the valve 115 is controlled by a control section in the control unit 30. For example, when the pump of the pressurizing section 113 supplies gas to the processing liquid storage section 111 and the valve 115 is opened in response to an operation command from the control section, the heated processing liquid in the pressurized processing liquid storage section 111 is pumped and supplied to the injection pipe 13 of the processing tank 12 via the piping 114.

[0036] 3, the processing tank 12 includes an injection pipe 13 for supplying the processing liquid into the processing tank 12, an inner tank 14 for storing the processing liquid, an outer tank 15 provided on the periphery of the upper opening of the inner tank 14, and a heat insulating material 16. Fig. 3 is a cross-sectional view showing an outline of the processing tank 12 of the solidified film forming unit 10 in the substrate processing apparatus 1 of this embodiment.

[0037] The injection pipe 13 is provided at the bottom of the processing tank 12, and enables the processing liquid to be supplied upflow to the inner tank 14. The inner tank 14 stores the processing liquid therein, thereby enabling the group of substrates W held in the holder 20 to be immersed in the processing liquid. The outer tank 15 enables the processing liquid that has overflowed from the inner tank 14 to be collected.

[0038] The heat insulating material 16 covers the outer surface of the treatment tank 12. More specifically, the heat insulating material 16 covers the outer surfaces of the inner tank 14 and the outer tank 15 without any gaps. This suppresses or reduces heat exchange with the outside air on the outer surfaces of the inner tank 14 and the outer tank 15, and prevents the temperature of the stored treatment liquid from changing. In this embodiment, the outer surface of the peripheral portion of the outer surface of the inner tank 14 surrounded by the outer tank 15 is not covered with the heat insulating material 16, but the present invention is not limited to this embodiment. In other words, the outer surface of the peripheral portion of the inner tank 14 of the present invention may also be covered with the heat insulating material 16.

[0039] The shape of the heat insulating material 16 is not particularly limited, and examples thereof include a sheet, plate, mat, or blanket shape. The constituent material of the heat insulating material 16 is not particularly limited, and examples thereof include ceramic fiber, silica fiber, alumina fiber, glass wool, rock wool, and the like. The thickness of the heat insulating material 16 is not particularly limited, and can be set appropriately. The method of covering the outer surface of the treatment tank 12 with the heat insulating material 16 is not particularly limited, and examples thereof include a method of adhering a sheet-shaped heat insulating material 16 with an adhesive or the like.

[0040] It is preferable that the temperature of the processing liquid in the processing tank 12 (i.e., the temperature measured by the processing liquid temperature measuring unit 40) is the same as the temperature of the processing liquid after heating by the heating unit 112 of the processing liquid supply unit 11. That is, it is preferable that the lower limit of the temperature of the processing liquid in the processing tank 12 is higher than room temperature. Also, it is preferable that the upper limit is a temperature lower than the boiling point of the processing liquid. Note that, when the precipitation temperature at which the sublimable substance starts to precipitate in the processing liquid is higher than room temperature, it is preferable that the temperature of the processing liquid in the processing tank 12 is higher than the precipitation temperature. This makes it possible to suppress changes in the concentration of the processing liquid in the processing tank 12.

[0041] As shown in FIG. 4, the holding part (lifter) 20 includes a flat back plate 21 and a plurality (three) of holding rods 22. The holding part 20 is a member configured to support a plurality of substrates W in an upright position by contacting them from below. FIG. 4 is a side view showing a schematic configuration of the holding part 20 and the lifting mechanism 23 in the substrate processing apparatus 1 of this embodiment. The back plate 21 stands upright, and at its lower end, the holding rods 22 extend in one direction so as to be perpendicular to the back plate 21. The holding rods 22 are provided with a plurality of grooves 24 arranged in the extending direction. The plurality of grooves 24 are arranged at equal intervals and spaced apart from each other. Furthermore, each groove 24 extends in a direction perpendicular to the extending direction of the holding rods 22, and can fit a plurality of substrates W in an upright position. As a result, the holding rods 22 can contact and support the group of substrates W from below in an upright position, thereby holding the group of substrates W collectively. The number of holding rods 22 is not particularly limited as long as there is more than one. The number of grooves 24 provided in the holding rods 22 is also not particularly limited, and may be set appropriately depending on the number of substrates W to be held. In this specification, the "upright position" refers to a position in which the surface (main surface, pattern-forming surface) of the substrate W is aligned approximately vertically to a horizontal plane, and includes the vertical position.

[0042] As shown in Fig. 4, the lifting mechanism 23 includes a connecting member 25, a lifting column 26, a ball screw 27, a lifting base 28, and a motor 29. The connecting member 25 extends from the upper end back surface of the back plate portion 21 in a direction perpendicular to the back plate portion 21 (parallel to the direction indicated by the arrow Y). The lifting column 26 is attached to the lower surface of the connecting member 25 at its upper end. The lifting column 26 is attached to the lifting base 28 at its lower end. The ball screw 27 is connected to a rotating shaft of the motor 29. The ball screw 27 is screwed into the lifting base 28 in a state where it penetrates the lifting base 28. The motor 29 is electrically connected to a control unit 30.

[0043] The lifting mechanism 23 can raise or lower the holding part 20 in the X direction shown in Figs. 1(a), 1(b) and 4 in response to an operation command from the control part 31 in the control unit 30. The lifting mechanism 23 can also stop the holding part 20 in the treatment tank 12. More specifically, when the motor 29 receives an operation command to raise from the control unit 30 and drives, the ball screw 27 rotates, and the lifting column 26 rises together with the lifting base 28. Accordingly, the back plate part 21 also rises via the connecting member 25 connected to the lifting column 26. Furthermore, when the motor 29 receives an operation command to lower from the control unit 30 and drives in the reverse direction, the ball screw 27 rotates in the reverse direction, and the lifting column 26 descends together with the lifting base 28. Accordingly, the back plate part 21 also descends via the connecting member 25 connected to the lifting column 26. In this manner, by raising and lowering the back plate 21 while the group of substrates W is supported from below by the holding rods 22, the holding part 20 holding the group of substrates W collectively can be moved into or removed from the processing tank 12. More specifically, the lifting mechanism 23 raises and lowers the holding part 20 between a retreat position shown in FIG. 1(a) and a processing position shown in FIG. 1(b). In FIG. 1(a), the holding part 20 holding the group of substrates W is in a retreat position above the processing tank 12 so as not to be immersed in the processing liquid. In FIG. 1(b), the holding part 20 holding the group of substrates W is in a processing position in the processing tank 12 so as to be immersed in the processing liquid stored in the inner tank 14 of the processing tank 12. In this specification, the "retreat position" means a position above the processing tank 12 where at least the holding part 20 does not contact the liquid surface of the processing liquid. In addition, in this specification, the "processing position" refers to a position within the inner bath 14 of the processing bath 12 where the group of substrates W are completely immersed in the processing liquid.

[0044] The treatment liquid temperature measuring section (thermometer) 40 measures the temperature of the treatment liquid stored inside the inner tank 14 (see FIGS. 1(a), 1(b) and 2).

[0045] The treatment liquid temperature measuring unit 40 may be, for example, a thermocouple. The treatment liquid temperature measuring unit 40 is electrically connected to the control unit 30 and can transmit measurement data relating to the temperature of the treatment liquid to the control unit 30.

[0046] The position of the processing liquid temperature measuring unit 40 in the inner bath 14 is not particularly limited, but it is preferably a position that does not interfere with the elevation and lowering of the holder 20. Furthermore, the position at which the processing liquid temperature measuring unit 40 measures the temperature of the processing liquid is preferably near the liquid surface of the processing liquid, taking into consideration the possibility that a temperature distribution may occur in the processing liquid stored in the inner bath 14. This makes it possible to grasp a temperature close to the temperature of the meniscus of the processing liquid that comes into contact with the surface of the substrate W and where a Marangoni flow may occur.

[0047] The processing liquid temperature measuring unit 40 may be configured to measure the temperature of the processing liquid at a plurality of different positions in the inner bath 14. Alternatively, the processing liquid temperature measuring unit 40 may be disposed at a plurality of different positions in the inner bath 14 to measure the temperature. By measuring the temperature of the processing liquid at a plurality of different positions in the inner bath 14, the uniformity of the temperature of the processing liquid stored in the inner bath 14 can be confirmed and evaluated. The measured temperature may be expressed as the average value of the temperatures measured at a plurality of different positions. In this case, the average value can be calculated by an arithmetic average, a weighted average, or the like.

[0048] The control unit 30 is electrically connected to each part of the substrate processing apparatus 1 and controls the operation of each part. For example, as shown in Fig. 5, the control unit 30 has at least a control unit 31, a storage unit 32, and an input unit 33. Fig. 5 is an explanatory diagram showing a schematic configuration of the control unit 30 in the substrate processing apparatus 1 of the present embodiment.

[0049] The control unit 31 is not particularly limited, and may be, for example, a central processing unit (CPU) or a micro processing unit (MPU) that performs various arithmetic processing. The storage unit 32 includes a ROM, which is a read-only memory that stores a basic program, a RAM, which is a readable and writable memory that stores various information, and a magnetic disk that stores control software, data, and the like. The magnetic disk stores substrate processing conditions corresponding to the substrate W in advance. The magnetic disk also stores film forming conditions (details of which will be described later) corresponding to the processing liquid. The control unit 31 reads out a substrate processing program from the storage unit 32, and the control unit 31 controls each unit of the substrate processing apparatus 1 according to the contents of the program. The input unit 33 may be, for example, a keyboard or a mouse. Data input from the input unit 33 is accepted by the control unit 31, and may be stored in the storage unit 32 as necessary.

[0050] The control unit 31 controls the heating unit 112 of the processing liquid supply unit 11 to adjust the temperature of the processing liquid stored in the processing liquid storage unit 111 based on the substrate processing conditions read out from the memory unit 32. This temperature adjustment makes it possible to control the processing liquid stored in the processing liquid storage unit 111 to be within a temperature range that is higher than room temperature and lower than the boiling point of the processing liquid.

[0051] Furthermore, the control unit 31 controls the pump in the pressurizing unit 113 of the processing liquid supply unit 11 to adjust the pressure in the processing liquid storage unit 111 based on the substrate processing conditions read out from the memory unit 32. This pressure adjustment makes it possible to control the supply amount of the heated processing liquid that is pumped from the processing liquid storage unit 111 to the processing tank 12. Furthermore, the control unit 31 controls the valve 115 in the processing liquid supply unit 11 to open and close based on the substrate processing conditions. This allows the control unit 31 to control the timing of supply of the processing liquid. Furthermore, when an agitation unit is provided in the processing liquid storage unit 111, the control unit 31 also controls the agitation unit based on the substrate processing conditions.

[0052] Furthermore, the control unit 31 raises and lowers or stops the holding unit 20 by controlling the raising and lowering operation of the lifting mechanism 23 based on the film formation conditions read out from the memory unit 32. The control unit 31 controls the raising and lowering operation of the lifting mechanism 23 to control the speed at which the holding unit 20 rises based on the film formation conditions. This controls the lifting speed of the group of substrates W collectively held by the holding unit 20. The control unit 31 also controls the stopping operation of the lifting mechanism 23 to control the time that the holding unit 20 remains in the processing bath 12 based on the film formation conditions. This controls the immersion time of the group of substrates W collectively held by the holding unit 20 in the processing liquid.

[0053] In this specification, the term "pull-up speed" refers to the speed at which the surface of the substrate W leaves the surface of the processing liquid. Therefore, when the height of the processing liquid surface does not decrease but remains constant, the pull-up speed refers to the rising speed of the substrate W relative to the surface of the processing liquid. When the height of the processing liquid surface decreases, the pull-up speed is expressed as the sum of the rising speed of the substrate W relative to the surface of the processing liquid and the falling speed of the surface of the processing liquid. In this specification, the term "immersion time" refers to the time during which the entire surface or the pattern-formed surface of the substrate W is immersed in the processing liquid and in contact with the processing liquid. In addition, the number of times that a group of substrates W are immersed in the processing liquid is usually one. Therefore, the immersion time refers to the contact time with the processing liquid during one immersion.

[0054] Here, the film formation conditions stored in the memory unit 32 include conditions that specify the lifting speed of the group of substrates W so that a solidified film having a target film thickness (hereinafter sometimes referred to as "target film thickness") is formed according to the temperature of the processing liquid in the processing tank 12. More specifically, the film formation conditions include the temperature of the processing liquid stored in the processing tank 12, the target film thickness of the solidified film to be formed, and the lifting speed of the substrates W, each of which is associated with the temperature of the processing liquid. The film formation conditions also include conditions that specify the immersion time of the group of substrates W required for the substrates W to be heated by the heated processing liquid in the processing tank 12 and reach a desired substrate temperature.

[0055] In this embodiment, the film formation conditions including those that define the immersion time of the group of substrates W are used for the following reason. That is, as shown in Fig. 6, for example, when the substrate W is immersed in a processing liquid 37 containing a solvent with a high vapor pressure and then the substrate W is pulled up, the solvent contained in the processing liquid 37 evaporates from the surface of the substrate W at the same time as the substrate W is pulled up. Therefore, solutes such as a sublimable substance 38 are precipitated on the surface of the substrate W due to the evaporation of the solvent, and as a result, a solidified film 36 containing the sublimable substance 38 is formed. Fig. 6 is an explanatory diagram that typically shows how the solidified film 36 is formed on the surface of the substrate W pulled up from the processing liquid 37.

[0056] Here, if the temperature of the processing liquid 37 is high, the substrate W immersed in the processing liquid 37 is heated and reaches a high temperature. When the substrate W is lifted up from the processing liquid 37 in this state, the meniscus portion 37A where the processing liquid 37 contacts the surface of the substrate W also reaches a high temperature, similar to the substrate W. On the other hand, the temperature of the liquid surface portion 37B of the processing liquid 37 is lower than the internal temperature due to contact with the outside air. As a result, the surface tension of the meniscus portion 37A of the processing liquid 37 is relatively smaller than that of the liquid surface portion 37B, and the surface tension becomes non-uniform. In general, when the surface tension of the liquid surface is non-uniform, a Marangoni flow occurs in which the liquid flows from a place with low surface tension to a place with high surface tension. In the present invention, the meniscus portion 37A of the processing liquid 37 tries to flow toward the processing bath 12 due to the non-uniformity of the surface tension between the meniscus portion 37A and the liquid surface portion 37B. As a result, the processing liquid 37 on the surface of the substrate W has good liquid drainage. When the drainage of the processing liquid 37 is improved, the time required from when the surface tension of the processing liquid 37 starts to act on the pattern until the solidified film 36 is formed can be shortened, and the solidified film 36 can be formed before the collapse of the pattern caused by the surface tension occurs. As a result, the solidified film 36 can be formed while reducing or preventing the collapse of the pattern caused by the surface tension of the processing liquid 37.

[0057] (Substrate processing method) Next, a substrate processing method using the substrate processing apparatus 1 of this embodiment will be described below with reference to the drawings.

[0058] As shown in Fig. 7, the substrate processing method of this embodiment includes at least a heating step S1 of heating a processing liquid, an immersion step S2 of immersing a group of substrates W collectively in the processing liquid, and a solidified film forming step S3 of forming a solidified film on each surface of the group of substrates W. Fig. 7 is a flowchart showing an example of an overall flow of the substrate processing method according to this embodiment.

[0059] The heating step S1 is a step of heating the processing liquid stored in the processing liquid storage section 111 of the processing liquid supply section 11. Based on an operation command from the control section 31, the heating section 112 heats the processing liquid stored in the processing liquid storage section 111. When the temperature of the processing liquid reaches a predetermined temperature by this heating, the control section 31 issues an operation command to the pressurizing section 113 to supply the gas stored in the gas tank to the processing liquid storage section 111 through the piping. The control section 31 also opens the valve 115. As a result, the heated processing liquid is pressure-fed to the injection pipe 13 of the processing tank 12 through the piping 114. Furthermore, the heated processing liquid pressure-fed to the injection pipe 13 is supplied in a predetermined amount into the inner tank 14 of the processing tank 12 by upflow supply.

[0060] Here, the outer surfaces of the inner tank 14 and the outer tank 15 are tightly covered with a heat insulating material 16. Therefore, the temperature of the heated treatment liquid supplied into the inner tank 14 is well maintained.

[0061] The immersion step S2 is a step of immersing the group of substrates W held by the holder 20 in the processing liquid 37 stored in the processing bath 12. That is, first, the plurality of substrates W are held by the holder 20 in the retreat position shown in FIG. 1(a). At this time, the plurality of substrates W are held so as to be in an upright position with respect to a horizontal plane. When the control unit 31 receives a film formation instruction for a solidified film from the input unit 33, it reads out the film formation conditions from the storage unit 32. Furthermore, the control unit 31 operates the lifting mechanism 23 based on the film formation conditions, and lowers the holder 20 to the processing position shown in FIG. 1(b), that is, into the inner bath 14 of the processing bath 12. As a result, the group of substrates W held by the holder 20 in an upright position are immersed in the processing liquid 37 all at once. The descent speed of the group of substrates W when the group of substrates W is immersed in the processing liquid 37 is not particularly limited, but is preferably a constant speed. The group of substrates W is immersed in the processing liquid 37 until the group of substrates W is heated and the temperature of the group of substrates W becomes equal to the temperature of the processing liquid 37 .

[0062] The solidified film forming step S3 is a step of lifting up the group of substrates W immersed in the processing liquid 37 stored in the processing tank 12 and forming a solidified film 36 on the surface of each substrate W. That is, after immersion, the control unit 31 operates the lifting mechanism 23 based on the film formation conditions to lift the holder 20 to the retreat position shown in Fig. 1(a), i.e., above the inner tank 14 of the processing tank 12. As a result, the group of substrates W in an upright position are lifted up collectively from the processing liquid 37.

[0063] The direction in which the group of substrates W are pulled up (the direction in which the holder 20 is raised) is not particularly limited, but is preferably a direction perpendicular to the liquid surface (horizontal surface) of the processing liquid 37.

[0064] When the group of substrates W is lifted up from the processing liquid 37, the solidified film 36 is formed on the surface of the group of substrates W during the lifting. That is, for example, when a solvent with a high vapor pressure is used as the solvent contained in the processing liquid 37, as shown in FIG. 6, when the substrate W is lifted up from the processing liquid 37, the solvent contained in the processing liquid 37 evaporates on the surface of the substrate W at the same time. As a result, solutes such as sublimable substance 38 are precipitated on the surface of the substrate W due to the evaporation of the solvent, and the solidified film 36 containing the sublimable substance 38 is formed. In addition, in this embodiment, due to the effect of the Marangoni flow described above, the processing liquid 37 is well drained when the substrate W is lifted up. Therefore, the solidified film 36 is formed before the surface tension of the processing liquid 37 acts on the pattern and the pattern collapses. As a result, the solidified film 36 can be formed while suppressing or reducing the occurrence of the collapse of the pattern.

[0065] The immersion time of the substrates W in the processing liquid 37 and the lifting speed of the substrates W are determined by the control unit 30, for example, as follows. That is, when the temperature of the processing liquid 37 in the inner tank 14 is measured by the processing liquid temperature measuring unit 40 and the target thickness of the solidified film to be formed is input by the input unit 33, the control unit 31 reads out information on the film formation conditions from the storage unit 32. Furthermore, the control unit 31 determines the immersion time of the substrates W in the processing liquid 37 and the lifting speed of the substrates W based on the target thickness and the temperature of the processing liquid 37 and with reference to the read-out film formation conditions. Next, the control unit 31 issues an operation command to the lifting mechanism 23 based on the determined immersion time, and performs immersion of the substrates W in the processing liquid 37 by the holder 20. Furthermore, when immersion of the substrates W in the processing liquid 37 is completed, the control unit 31 issues an operation command to the lifting mechanism 23 based on the determined lifting speed, and performs lifting of the substrates W by the holder 20.

[0066] While the group of substrates W is immersed in the processing liquid 37, the holder 20 preferably remains stationary in the processing liquid 37.

[0067] Furthermore, the lifting speed of the group of substrates W may be constant from the start to the end of lifting, or may be changed according to the lifting distance of the group of substrates W. When the lifting speed is constant, if there is no change over time in the physical properties (e.g., density, viscosity, etc.) of the processing liquid 37, the uniformity of the film thickness of the solidified film 36 can also be controlled with high precision. As a result, when the solidified film 36 is formed or sublimated, it is possible to reduce non-uniform application of stress to the pattern of the substrate W, and further reduce the occurrence of pattern collapse.

[0068] It is preferable that the surface of the processing liquid 37 is stationary when the group of substrates W is pulled up. As a result, while the substrates W are being pulled up from the processing liquid 37, the meniscus portion 37A of the surface of the processing liquid 37 formed by the interaction with the surfaces of the substrates W is constant, and therefore the cutting off of the processing liquid 37 is also constant, making it possible to form a solidified film 36 with even more uniform thickness.

[0069] Moreover, the substrates W are lifted up from the processing liquid 37 in an upright position. This method allows the deposited sublimable material 38 to grow in crystal in a plane, thereby forming the solidified film 36. That is, the deposited sublimable material 38 can be prevented from growing in crystal in three dimensions, which prevents film defects caused by grain boundary generation, and reduces or prevents pattern collapse. Furthermore, it is preferable that the upright position of the substrates W is constant while the substrates W are lifted up from the processing liquid 37. This allows the solidified film 36 to be formed with a further improved uniformity in film thickness. Furthermore, in the method of forming the solidified film 36 on the surface of the substrates W at the same time as the substrates W are lifted up from the processing liquid 37, the time during which the stress caused by the formation of the solidified film 36 is applied to the pattern on the surface of the substrates W can be shortened as much as possible. Particularly in the present invention, the Marangoni flow is generated when the substrates W are lifted up to improve the liquid cut-off of the processing liquid 37 on the surface of the substrates W, which shortens the time during which the surface tension of the processing liquid 37 acts on the pattern, thereby enabling the solidified film 36 to be formed before the pattern collapses. As a result, the occurrence of pattern collapse can be further reduced or prevented. Furthermore, in the formation of the solidified film 36 of this embodiment, the substrates W are immersed in the processing liquid 37 all at once, so that the liquid remaining on the surface of each substrate W can be replaced with the processing liquid 37 for the substrates W all at once. In particular, in a substrate having a three-dimensional structure such as a three-dimensional NAND structure, it takes a significant amount of time to replace the liquid in a trench formed in a direction perpendicular to the substrate surface and an ON (oxide film-nitride film) structure extending horizontally from the trench. Therefore, if a plurality of substrates are processed one by one by single-wafer processing, it takes a long time. However, in the substrate processing method of this embodiment, the substrates W are immersed in the processing liquid 37 all at once, so that the substrates W having such a three-dimensional structure can be replaced with the processing liquid 37 all at once. Therefore, the processing can be performed in an extremely short time compared to the case where a plurality of substrates W are processed one by one by single-wafer processing. Furthermore, the amount of processing liquid used can be reduced compared to the case where the processing liquid is replaced by the single-wafer method.

[0070] When the group of substrates W are collectively lifted out of the processing liquid 37 and the holder 20 returns to the retreat position, the solidified film forming step S3 is completed.

[0071] As described above, in the substrate processing method of the present embodiment, a plurality of substrates W are immersed in the processing liquid 37 at once, and then the solidified film 36 is formed while the substrates W are immersed in the processing liquid 37 at once and then pulled out of the processing liquid 37 at once. In addition, the substrates W are heated while being immersed in the processing liquid 37, so that a Marangoni flow is generated when the substrates W are pulled out, and the processing liquid 37 is smoothly drained off from the surface of each substrate W. As a result, in the present embodiment, the solidified film 36 can be formed before the surface tension of the processing liquid 37 acts on the pattern and causes the pattern to collapse. Therefore, compared to the case where a solidified film is formed on the surface of a substrate by a single-wafer processing method in which the substrates are processed one by one, the substrate processing can be performed while reducing or preventing collapse of the pattern.

[0072] <Other> In this embodiment, the present invention has been described by taking as an example a case where the outer surface of the treatment tank is covered with a heat insulating material. However, the present invention is not limited to this embodiment. For example, the treatment tank may be provided with a heat storage section instead of the heat insulating material.

[0073] The heat storage section may be, for example, a configuration in which the side and / or bottom of the treatment tank has a double structure, and a heat storage material is accommodated in the space between the inner wall and the outer wall. With such a structure, the heat storage material absorbs the heat discharged from the inner wall of the treatment tank, thereby increasing the heat capacity of the treatment tank itself. This makes it possible to stabilize the temperature environment in the treatment tank, and to maintain the temperature of the treatment liquid stored in the treatment tank constant. The heat storage material is not particularly limited, and may be, for example, a liquid such as water. [Explanation of symbols]

[0074] 1...substrate processing apparatus, 10...solidified film forming section, 11...processing liquid supply section, 12...processing tank, 13...injection tube, 14...inner tank, 15...outer tank, 16...insulating material, 20...holding section, 21...back plate section, 22...holding rod, 23...lifting mechanism, 24...groove section, 25...connecting member, 26...lifting column, 27...ball screw, 28...lifting base, 29...motor, 30...control unit, 31...control section, 32...storage section, 33...input section, 36...solidified film, 37...processing liquid, 38...sublimable substance, 40...processing liquid temperature measuring section (thermometer), 111...processing liquid storage section, 112...heating section, 113...pressurizing section, 114...piping, 115...valve, S1...heating process, S2...immersion process, S3...solidified film forming process

Claims

1. A substrate processing method for collectively processing a plurality of substrates each having a pattern-formed surface, comprising the steps of: an immersion step of immersing a plurality of the substrates collectively in a treatment liquid stored in a treatment tank and containing a sublimable substance and a solvent; a solidified film forming step of evaporating the solvent while simultaneously lifting the plurality of substrates in an upright position from the processing liquid to precipitate the sublimable substance, thereby forming a solidified film containing the sublimable substance on the surface of the substrate; Including, a time required for the sublimable substance to be precipitated by evaporation of the solvent to form the solidified film, the time required for the pattern on the pattern-formed surface to collapse, the substrate processing method comprising:

2. The method further includes a heating step of heating the treatment liquid before the treatment liquid is stored in the treatment tank; the immersion step is performed while collectively heating the plurality of substrates by immersing the plurality of substrates collectively in the treatment liquid heated in the heating step; 2. The substrate processing method according to claim 1, wherein the solidified film forming process is performed while generating a Marangoni flow in which the processing liquid on the surfaces of the substrates flows toward the processing liquid stored in the processing tank when the heated plurality of substrates are lifted up collectively in an upright position.

3. 2. The substrate processing method according to claim 1, wherein the solvent in the processing liquid has a vapor pressure of 500 Pa or more and 90 kPa or less at 20.degree.

4. 3. The substrate processing method according to claim 2, wherein the heating step heats the processing liquid before being stored in the processing bath to a temperature range above room temperature and below a boiling point of the processing liquid.

5. The outer surface of the treatment tank is covered with a heat insulating material, 3. The substrate processing method according to claim 2, wherein the immersion step and the solidified film forming step are performed while maintaining the temperature of the processing liquid heated in the heating step.

6. A substrate processing apparatus for collectively processing a plurality of substrates each having a pattern-formed surface, comprising: a treatment liquid storage section for storing a treatment liquid containing a sublimable material and a solvent; a heating unit that heats the treatment liquid stored in the treatment liquid storage unit; a processing tank that is heated by the heating unit and stores the processing liquid supplied from the processing liquid storage unit; a holding section for collectively holding the plurality of substrates in an upright position; a lifting mechanism that lifts and lowers the holding unit relative to the treatment bath to immerse the plurality of substrates held by the holding unit in the treatment liquid all at once, or remove the plurality of substrates held by the holding unit from the treatment liquid all at once; A control unit that controls the heating unit and the lifting mechanism; Equipped with The immersion and removal are performed by: a process for forming a solidified film containing the sublimable substance on a surface of the substrate by evaporating the solvent while simultaneously lifting up the substrates immersed in the processing liquid, The control unit is by controlling the lifting mechanism to adjust the immersion time of the plurality of substrates in the treatment liquid, the plurality of substrates are collectively heated in the treatment liquid heated by the heating unit; The substrate processing apparatus further comprises: a substrate lifting mechanism for controlling the lifting mechanism to lift the heated substrates collectively in an upright position, the substrate lifting mechanism generating a Marangoni flow in which the processing liquid on the surfaces of the substrates flows toward the processing liquid stored in the processing tank.

7. 7. The substrate processing apparatus according to claim 6, wherein the solvent in the processing liquid has a vapor pressure of 500 Pa or more and 90 kPa or less at 20.degree.

8. The substrate processing apparatus according to claim 6 , wherein the heating section heats the processing liquid stored in the processing liquid storage section to a temperature range above room temperature and below a boiling point of the processing liquid.

9. The outer surface of the treatment tank is covered with a heat insulating material, The substrate processing apparatus according to claim 6 , wherein the temperature of the processing liquid heated by the heating section is maintained.

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