Substrate cleaning apparatus and substrate cleaning method

Abstract

This invention improves the throughput of a substrate cleaning method using a cryogenic cleaning method. The substrate cleaning apparatus of an embodiment includes: a rotating holding unit for holding a substrate; a liquid supply unit for supplying liquid to a first surface of the substrate; a first cooling medium supply unit for supplying a first cooling medium toward a second surface of the substrate opposite to the first surface; a second cooling medium supply unit for supplying a second cooling medium toward the first surface; and a control unit for controlling the rotating holding unit, the first cooling medium supply unit, the second cooling medium supply unit, and the liquid supply unit to perform a cleaning process on the substrate. The cleaning process includes: a first cooling process, in which the liquid on the first surface is frozen to form a frozen body by supplying the first cooling medium toward the second surface; and a second cooling process, in which the frozen body is further cooled by supplying the second cooling medium toward the first surface.

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a substrate cleaning apparatus and a substrate cleaning method. [Previous Technology]

[0002] Conventionally, cryogenic cleaning is known as a substrate cleaning method for removing foreign matter such as particles adhering to the surface of substrates such as semiconductor substrates, imprinting templates, and photolithography masks. In cryogenic cleaning, pure water is first supplied to the surface of the substrate, and the substrate is rotated, thereby forming a water film on the surface of the substrate. After the water film is formed, cooling gas is supplied to the substrate to freeze the water film, and the volume expansion force during the phase transition from liquid to solid is used to draw the particles into the ice film. Then, by supplying pure water to the substrate again to melt the ice film, the pure water and particles can be removed from the substrate together. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-026436 [Summary of the Invention]

[0004] [Problem to be Solved by the Invention] According to the described cryo-cleaning method, foreign matter such as particles adhering to the surface of a substrate can be effectively removed. However, for example, in the manufacturing process of semiconductor devices, since multiple semiconductor substrates are cleaned in each manufacturing step, the cleaning process alone takes a lot of time. Therefore, in recent years, there has been a desire to increase the throughput of the cleaning process.

[0005] One of the objectives of this invention is to increase the throughput of a substrate cleaning method using a cryogenic cleaning method.

[0006] In addition, one of the other issues of the present invention is to provide a substrate cleaning apparatus capable of performing a substrate cleaning method with increased throughput.

[0007] [Technical Means for Solving the Problem] A substrate cleaning apparatus according to an embodiment of the present invention includes: a rotating holding section for holding a substrate; a liquid supply section for supplying liquid to a first surface of the substrate; a first cooling medium supply section for supplying a first cooling medium to a second surface of the substrate opposite to the first surface; a second cooling medium supply section for supplying a second cooling medium to the first surface; and a control section for controlling the rotating holding section, the first cooling medium supply section, the second cooling medium supply section and the liquid supply section to perform a cleaning process on the substrate, the cleaning process including: a first cooling process, in which the liquid on the first surface is frozen to form a frozen body by supplying the first cooling medium to the second surface; and a second cooling process, in which the frozen body is further cooled by supplying the second cooling medium to the first surface.

[0008] A substrate cleaning method according to an embodiment of the present invention includes: supplying liquid to a first surface of a substrate, supplying a first cooling medium to a second surface of the substrate opposite to the first surface to freeze the liquid on the first surface to form a frozen body, and supplying a second cooling medium to the first surface to further cool the frozen body.

Implementation Method

[0010] Hereinafter, a substrate cleaning apparatus according to one embodiment of the present invention will be described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the description of the examples shown below. Furthermore, in the drawings referred to in this embodiment, the same symbols are sometimes used to mark the same parts or parts having the same function, or letters are used after the same symbols, and repeated descriptions are omitted.

[0011] In the specification and claims of this application, "upper" refers to the direction in which the mounting surface of the substrate cleaning apparatus (e.g., the factory floor) faces when the substrate cleaning apparatus is set to a state where it can be used normally, and "lower" refers to the opposite direction to "upper". In addition, with the center of the substrate cleaning apparatus when viewed from above as a reference, the direction away from the center is called "outer side", and the direction closer to the center is called "inner side".

[0012] <First Embodiment>

[0013] As an example of a substrate cleaning apparatus according to one embodiment of the present invention, a substrate cleaning apparatus for cleaning semiconductor substrates (e.g., semiconductor wafers) will be described. However, the embodiments of the substrate cleaning apparatus are not limited to an apparatus for cleaning semiconductor substrates, and can also be applied to an apparatus for cleaning other substrates. For example, it can also be applied to an apparatus for cleaning substrates such as imprinting templates, photolithography masks, and plate-shaped bodies used in microelectromechanical systems (MEMS).

[0014] In the following description, a semiconductor substrate without a film (insulating film or conductive film) formed on the surface (surface or back) to be processed is illustrated, but the example is not limited to this. For example, the semiconductor substrate may be a semiconductor substrate with an unprocessed film formed on the surface to be processed, or a semiconductor substrate with a processed film (pattern) formed on the surface to be processed. In addition, in the following description, an example is shown using cooling gas as the cooling medium and pure water as the cleaning fluid. Therefore, the liquid (cleaning fluid) held on the surface (surface) to be processed on the substrate W is sometimes referred to as a "water film" or "liquid film", and the frozen body formed by freezing the liquid is referred to as an "ice film" or "freezing film".

[0015] [Structure of the substrate cleaning apparatus 100]

[0016] FIG1 is a side view schematically showing the structure of the substrate cleaning apparatus 100 according to the first embodiment. FIG2 is a cross-sectional view schematically showing the structure of the main parts of the substrate cleaning apparatus 100 according to the first embodiment. Hereinafter, the substrate cleaning apparatus 100 will be described with reference to FIG1 and FIG2. The substrate cleaning apparatus 100 is, for example, an apparatus that is disposed in a semiconductor device manufacturing plant and performs a cleaning process using a freeze cleaning method on a substrate W, which is a cleaning object (workpiece), between various manufacturing processes of semiconductor devices.

[0017] The substrate cleaning apparatus 100 of this embodiment includes a rotating holding part 110, a first cooling medium supply part 120, a second cooling medium supply part 130, a liquid supply part 140, a discharge cup part 150, and a control part 160. However, the structure of the substrate cleaning apparatus 100 is not limited to the example described above. Some of the components shown in FIG1 may be omitted, and other components may be added.

[0018] (Structure of the rotating retaining part 110)

[0019] The rotation holding part 110 includes a base part 111, a cover part 112, a holding part 113, and a drive part 114. The rotation holding part 110 has the following functions: holding the substrate W with the surface to be processed (here, the surface) facing upward, and rotating the substrate W about a rotation axis 11 that passes through the center of the rotation holding part 110 in the vertical direction. However, the structure of the rotation holding part 110 is not limited to the example described above; a part of the component may be omitted, or other components may be added.

[0020] The base portion 111 is a rotating body supporting the cover portion 112 or the retaining portion 113, and is a component with a generally circular shape when viewed from above. When viewed from above, a cylindrical portion 111a extending downward is provided at the center of the base portion 111. That is, an opening extending downward is provided at the center of the base portion 111 when viewed from above. As described later, a portion (lower portion 121b) of the nozzle head 121 of the first cooling medium supply portion 120 is embedded inside (the hollow portion) of the cylindrical portion 111a. The nozzle head 121 is supported by a frame (not shown) and separated from the base portion 111. The base portion 111 is capable of rotating about a rotation axis 11 passing through the center of the cylindrical portion 111a.

[0021] The cover portion 112 is a component disposed on the base portion 111 and having a generally circular shape when viewed from above. The cover portion 112 has an inner portion 112a located further inward than the retaining portion 113, and an outer portion 112b located further outward than the retaining portion 113. The inner portion 112a of the cover portion 112 is a portion fixed to the base portion 111, and its upper surface is an inclined surface that is higher towards the outer side. As will be described in detail later, the inclined surface provided in the inner portion 112a functions as a guide surface for guiding the cooling medium supplied to the back side of the substrate W outward. An opening portion 112aa is provided at the center of the inner portion 112a, and a portion of the nozzle head 121 (upper portion 121a) is embedded therein. The outer portion 112b of the cover portion 112 serves as a cover to protect the internal structure of the rotating retaining portion 110. Furthermore, in this embodiment, an example is shown in which the base portion 111 and the cover portion 112 are composed of different components, but the base portion 111 and the cover portion 112 may also be integrally formed components.

[0022] The retaining part 113, also known as a chuck pin, is provided in multiple portions at predetermined intervals on the outer periphery of the base part 111. The retaining part 113 has a cylindrical main body 113a configured to be rotatable by a drive mechanism (not shown) and a pin 113b provided at the upper end of the main body 113a. The pin 113b is located at a position separated from the rotation axis of the main body 113a. When the main body 113a rotates, the pin 113b moves inward and abuts against the side end of the substrate W, thereby retaining the substrate W. Conversely, when the main body 113a rotates in the opposite direction, the pin 113b moves outward and disengages from the side end of the substrate W, thereby releasing the substrate W.

[0023] The drive unit 114 is supported by a frame (not shown) and is connected to the lower end of the base unit 111 (i.e., the lower end of the cylindrical portion 111a). The drive unit 114 has the function of rotating the base unit 111 about the rotation axis 11. An opening 114a is provided at the center of the drive unit 114, and a portion (lower portion 121b) of the nozzle head 121 is inserted inside it. Since the drive unit 114 is not connected to the nozzle head 121, the drive unit 114 can rotate the base unit 111 while the nozzle head 121 is fixed.

[0024] (Structure of the first cooling medium supply unit 120)

[0025] The first cooling medium supply unit 120 includes a nozzle head 121, a dispersion plate 122, and a cooling medium supply device 123. The first cooling medium supply unit 120 has the function of supplying a cooling medium (first cooling medium) to cool the substrate W from the back side (second side). However, the structure of the first cooling medium supply unit 120 is not limited to the example described above; a part of the components may be omitted, or other components may be added.

[0026] In this embodiment, a cooling gas is used as the cooling medium for cooling the back side of the substrate W. Specifically, in this embodiment, nitrogen gas cooled to -120°C is used as the cooling gas. However, the cooling medium is not limited to the example described above; other inert gases such as argon and helium may also be used, as well as gases formed by vaporizing liquid nitrogen. Furthermore, a cooled liquid may be used instead of a cooling gas as the cooling medium.

[0027] The nozzle head 121 is a component for supplying cooling gas to the back side of the substrate W. The nozzle head 121 is located above the cylindrical portion 111a of the base portion 111, and includes an upper portion 121a with a generally V-shaped cross-section and a lower portion 121b with a cylindrical shape. As shown in FIG2, the upper portion 121a is disposed inside the opening 112aa of the cover portion 112, and the lower portion 121b is inserted into the inside of the cylindrical portion 111a of the base portion 111. However, the base portion 111 and the cover portion 112 are separate from the nozzle head 121. The base portion 111 and the cover portion 112 can rotate about the rotation axis 11, while the nozzle head 121 is fixed and does not rotate.

[0028] A through hole 121c is provided at the center of the nozzle head 121, connecting the lower end and the upper end along the rotation axis 11. Specifically, the rotation axis 11 is located at the center of the through hole 121c. The through hole 121c is a path through which cooling gas supplied from the cooling medium supply device 123 passes, and the cooling gas supplied from the lower end of the through hole 121c is released from the upper end of the through hole 121c toward the dispersion plate 122.

[0029] An inclined surface 121aa is provided on the upper surface of the upper portion 121a of the nozzle head 121, which is positioned higher and further outwards. In other words, a conical recess is formed on the upper surface of the upper portion 121a of the nozzle head 121. Therefore, a portion of the cooling gas reaching the upper surface of the nozzle head 121 via the through hole 121c flows upwards and outwards along the inclined surface 121aa provided on the upper surface of the upper portion 121a. That is, the inclined surface 121aa functions as a guide surface for guiding the cooling gas supplied to the back side of the substrate W outwards.

[0030] Furthermore, a groove 121ab is provided on the lower surface of the upper portion 121a of the nozzle head 121 in a circular shape when viewed from above. On the other hand, a protrusion 111b protruding upward is provided on the base portion 111, and the groove 121ab of the nozzle head 121 and the protrusion 111b of the base portion 111 are arranged to be separated from each other and facing each other. In this way, by having a structure (labyrinth structure) with a curved shape formed by the gap between the base portion 111 and the nozzle head 121, the cleaning liquid supplied to the substrate W through the gap can be prevented from entering the interior of the cover portion 112. In addition, this structure can also prevent unclean gases (such as gases containing dust particles) from leaking from the interior of the cover portion 112 to the space side used for processing the substrate W.

[0031] The dispersion plate 122 is disposed on the upper portion 121a of the nozzle head 121. Specifically, the dispersion plate 122 is disposed above the nozzle head 121 with a predetermined gap using screws or pins. The gap between the nozzle head 121 and the dispersion plate 122 is provided to allow cooling gas flowing outward along the upper surface (inclined surface 121aa) of the nozzle head 121 to flow into the inner portion 112a of the shroud 112. In addition, the dispersion plate 122 is configured such that, when the substrate W is held by the holding portion 113, the gap between the dispersion plate 122 and the substrate W is, for example, 1 mm or more and 5 mm or less (2 mm in this embodiment).

[0032] A plurality of through holes 122a connecting the upper and lower surfaces are provided in the dispersion plate 122. Although not shown in the figure, in this embodiment, a through hole 122a is provided in the center and a plurality of through holes 122a are provided in a manner surrounding the center. Cooling gas supplied through the through hole 121c of the nozzle head 121 rises in this state and thereby collides with the lower surface of the dispersion plate 122. At this time, a portion of the cooling gas touches the back surface of the substrate W through the through hole 122a of the dispersion plate 122. Afterward, the cooling gas reaching the substrate W flows in the gap between the upper surface of the dispersion plate 122 and the back surface of the substrate W and is discharged to the outside of the rotating holding part 110.

[0033] In this embodiment, one of a plurality of through holes 122a is disposed at the center of the dispersion plate 122, but the through hole 122a disposed at the center of the dispersion plate 122 is preferably disposed at a position offset relative to the rotation axis 11. The center position of the substrate W (the position intersecting the rotation axis 11) becomes the rotation center. Therefore, when the cooling gas touches the center position of the substrate W, it is cooled locally compared to other parts, which raises concerns about hindering the uniform cooling of the substrate W. By setting the position of the through hole 122a disposed at the center of the dispersion plate 122 to a position offset relative to the center position of the substrate W, the undesirable situation of only the center of the substrate W being cooled locally can be suppressed.

[0034] On the other hand, even when the through hole 122a is arranged at a position overlapping with the rotation axis 11, for example, by making the diameter of the through hole 122a arranged in the center smaller than the diameter of the through holes 122a arranged in other positions, local cooling of the center of the substrate W can be suppressed. That is, by reducing the contact area of ​​the cooling gas touching the center of the substrate W, the deviation in the temperature distribution of the substrate W can be mitigated. In this case, the diameter of the through hole 122a arranged in the center of the dispersion plate 122 can be smaller overall than the diameter of the through holes 122a arranged in other positions, or the diameter of the opening end facing the substrate W can be increased only by making the opening end tapered.

[0035] The cooling medium supply device 123 is a device that supplies cooling medium (here, cooling gas) to the nozzle head 121. Although not shown in the figure, the nozzle head 121 and the cooling medium supply device 123 are connected by piping or the like. Between the nozzle head 121 and the cooling medium supply device 123, a flow adjustment unit for adjusting the flow rate of the cooling gas or a screening program unit for removing foreign matter contained in the cooling gas may also be provided. Although not shown in the figure, in this embodiment, the cooling medium supply device 123 includes a gas tank for storing nitrogen, a cooler (cooling water circulation device) for cooling nitrogen, and a pump for delivering the cooled nitrogen to the nozzle head 121. However, the structure of the cooling medium supply device 123 is not limited to the example described above; any device that can supply cooled gas or liquid to the nozzle head 121 can be used.

[0036] (Structure of the second cooling medium supply unit 130)

[0037] The second cooling medium supply unit 130 includes a blocking member 131, a detection unit 132, a lifting mechanism 133, and a cooling medium supply device 134. The second cooling medium supply unit 130 has the function of supplying a cooling medium (second cooling medium) to cool the surface (first surface) side of the substrate W. Specifically, the second cooling medium supply unit 130 supplies a cooling medium to further cool the frozen body (ice film in this embodiment) formed on the surface of the substrate W. However, the structure of the second cooling medium supply unit 130 is not limited to the example described above; a part of the component may be omitted, or other components may be added.

[0038] In this embodiment, the same cooling gas (specifically, nitrogen cooled to -120°C) as the cooling medium used to cool the surface side of the substrate W is used. However, it is not limited to this example; the second cooling medium supply unit 130 may also use a different cooling medium than the first cooling medium supply unit 120. Furthermore, other types of cooling media may be used as the same as those used in the first cooling medium supply unit 120.

[0039] The blocking member 131 is a member that supplies cooling gas to the frozen body (here, an ice film) formed on the surface (processed surface) of the substrate W. Specifically, the blocking member 131 is composed of a plate-shaped member having a through hole 131a for supplying cooling gas. The blocking member 131 has a circular shape when viewed from above, and has a through hole 131a in the center. Cooling gas supplied from the cooling medium supply device 134 is supplied to the ice film formed on the surface of the substrate W through the through hole 131a.

[0040] In the example shown in FIG2, the through hole 131a is provided at a position overlapping with the rotation axis 11 (i.e., facing the through hole 121c of the nozzle head 121). However, it is not limited to this example; the through hole 131a may also be provided at a position offset relative to the rotation axis 11. The reason is the same as that explained for the through hole 122a provided in the dispersion plate 122. By offsetting the position of the through hole 131a relative to the center position of the substrate W, the undesirable situation where the temperature of the center part of the ice film formed on the surface of the substrate W is locally lower than that of other parts can be suppressed. In this embodiment, the opening end 131c on the lower side of the through hole 131a has a tapered shape that extends downward. Therefore, the contact area when the released cooling gas touches the ice film is widened, and the deviation of the temperature distribution of the ice film can be suppressed.

[0041] It is desirable that the area of ​​the side of the blocking member 131 facing the substrate W is equal to or larger than the area of ​​the surface of the substrate W. As will be described later, when cooling gas is supplied toward the surface of the substrate W, the blocking member 131 is brought close to the substrate W, forming a small gap between the blocking member 131 and the substrate W. In FIG. 1, the blocking member 131 approaching the substrate W is shown in dashed lines. The cooling gas released from the through hole 131a extends outward through the gap formed between the blocking member 131 and the substrate W (strictly speaking, the ice film), thereby cooling the entire surface of the ice film. Therefore, the area of ​​the side of the blocking member 131 facing the substrate W is set to be greater than or equal to the area of ​​the surface of the substrate W, so that the gap is formed to the outer edge of the substrate W. Furthermore, the width of the gap formed between the substrate W and the blocking member 131 is preferably the same as the width of the gap formed between the substrate W and the dispersion plate 122. For example, the width of the gap formed between the substrate W and the blocking member 131 only needs to be set to 1 mm or more and 5 mm or less. In this embodiment, the width of the gap is set to 2 mm.

[0042] The detection unit 132 has the function of detecting the formation of an ice film on the surface of the substrate W. In other words, the detection unit 132 has the function of detecting whether the liquid held on the surface of the substrate W has undergone a phase change to a solid. In this embodiment, a radiation thermometer is used as the detection unit 132 to measure the radiation temperature of the water film or ice film held on the surface of the substrate W. In this embodiment, three radiation thermometers, which serve as the detection units 132, are installed at different radial positions on the blocking member 131 at intervals. The three radiation thermometers only need to be different in radial position and do not need to be arranged in a row on the same straight line. As shown in FIG2, each radiation thermometer is arranged on the upper side of the blocking member 131 (that is, the side opposite to the side facing the substrate W). In addition, an opening 131b for allowing infrared light to pass through is provided at the position where each radiation thermometer is installed on the blocking member 131.

[0043] In this embodiment, an example is shown where three radiation thermometers are arranged on the blocking member 131 as the detection unit 132, but the number of radiation thermometers arranged is not limited to three. In addition, in this embodiment, a structure in which the radiation thermometers are mounted on the blocking member 131 is shown, but it is also possible to configure the radiation thermometers to be fixed to a member located on the outside of the blocking member 131 and to measure the radiation temperature of the water film or ice film from the inclined direction.

[0044] In addition, as the detection unit 132, an imaging device can be configured instead of a radiation thermometer. That is, by using the imaging device to photograph the water film or ice film held on the surface of the substrate W, and analyzing the photographed image, it is possible to detect whether the water has undergone a phase transformation into ice.

[0045] The lifting mechanism 133 has the function of moving the blocking member 131 in the vertical direction (up and down direction). The lifting mechanism 133 includes a first support frame 133a, a second support frame 133b, a support arm 133c, and a connecting part 133d. The first support frame 133a and the second support frame 133b are both cylindrical components, and the second support frame 133b is inserted into the hollow part of the first support frame 133a. The second support frame 133b is connected to a drive mechanism (not shown) and can slide inside the first support frame 133a. That is, the second support frame 133b can move relative to the first support frame 133a in the vertical direction, forming a support frame that can extend and retract in the vertical direction as a whole.

[0046] A support arm 133c is fixed near the upper end of the second support frame 133b. The support arm 133c is a component that connects the second support frame 133b to the connecting portion 133d, and supports the blocking member 131 via the connecting portion 133d. The connecting portion 133d is a component that connects the support arm 133c to the blocking member 131, and as shown in FIG2, it has a through hole 133da communicating with the through hole 131a of the blocking member 131. Cooling gas supplied from the cooling medium supply device 134 is released toward the substrate W via the through hole 133da of the connecting portion 133d and the through hole 131a of the blocking member 131.

[0047] By means of the lifting action based on the lifting mechanism 133, the blocking member 131 is configured to be able to move to a retracted position relatively far from the substrate W and an approaching position relatively close to the substrate W. The retracted position is a position where the blocking member 131 is sufficiently far away from the rotating holding portion 110, and is a position where the substrate W can be moved in and out relative to the rotating holding portion 110. The approaching position is a position where the blocking member 131 is sufficiently close to the rotating holding portion 110, and is a position where cooling processing of the substrate W based on the second cooling medium supply portion 130 is performed. In the approaching position, there is a gap between the substrate W and the blocking member 131 that ensures that the blocking member 131 does not come into contact with the water film or ice film held on the substrate W. However, the structure of the lifting mechanism 133 is not limited to the example described above, and can be any structure as long as it is a structure that allows the blocking member 131 to move in the vertical direction.

[0048] The cooling medium supply device 134 is a device that supplies cooling medium (here, cooling gas) to the shut-off member 131. Although not shown in the figure, the shut-off member 131 and the cooling medium supply device 134 are connected by piping or the like. In this embodiment, the structure of the cooling medium supply device 134 is the same as that of the cooling medium supply device 123. That is, the cooling medium supply device 134 includes a gas tank for storing nitrogen, a cooler (cooling water circulation device) for cooling nitrogen, and a pump for delivering the cooled nitrogen to the shut-off member 131. However, the structure of the cooling medium supply device 134 is not limited to the example described above; any device that can supply cooled medium to the shut-off member 131 is acceptable.

[0049] (Structure of liquid supply unit 140)

[0050] The liquid supply unit 140 has the function of supplying a cleaning liquid (cleaning solution) to the surface of the substrate W. For example, pure water or a liquid with water as the main component can be used as the cleaning solution. In this embodiment, pure water is used as the cleaning solution.

[0051] The liquid supply unit 140 includes a first support frame 141, a second support frame 142, and a supply nozzle 143. The first support frame 141 and the second support frame 142 are both cylindrical components, with the second support frame 142 inserted into the hollow portion of the first support frame 141. The second support frame 142 is connected to a drive mechanism (not shown) and can rotate inside the first support frame 133a. That is, the second support frame 142 can rotate relative to the first support frame 141 about a rotation axis 12.

[0052] Thus, in the liquid supply section 140, the second support frame 142 and the supply nozzle 143 fixed to the second support frame 142 rotate about the rotation axis 12. That is, the liquid supply section 140 is configured such that the liquid outlet 143a of the supply nozzle 143 can move between a retracted position that does not overlap with the substrate W and a supply position located above the center of the substrate W.

[0053] The discharge cup portion 150 includes a cylindrical member surrounding the rotating holding portion 110, which prevents liquid discharged from the surface of the substrate W from scattering in the surrounding area. The discharge cup portion 150 can be raised and lowered in the vertical direction by a lifting mechanism (not shown). That is, when the substrate W is moved in and out relative to the rotating holding portion 110, the discharge cup portion 150 moves downward, and before the cleaning process begins, the discharge cup portion 150 moves upward. When the water film held on the surface of the substrate W is discharged by rotating the substrate W, the discharge cup portion 150 receives the liquid that scatters in the surrounding area. In addition, although not shown, the discharge cup portion 150 has a container-type structure that contains the cleaning liquid that flows downward from contact with the inner wall surface located on the side of the rotating holding portion 110, and the accumulated cleaning liquid can be discharged from the discharge port provided at the bottom.

[0054] The control unit 160 controls the operation of the substrate cleaning apparatus 100. Specifically, the control unit 160 controls the rotation holding unit 110, the first cooling medium supply unit 120, the second cooling medium supply unit 130, and the liquid supply unit 140 to control the cleaning process on the substrate W. The control unit 160 includes a processing unit 161 and a storage unit 162. The processing unit 161 is, for example, a central processing unit (CPU). The storage unit 162 is, for example, read-only memory (ROM). In the control unit 160, the processing unit 161 reads and executes the control program 162a stored in the storage unit 162, thereby controlling the operation of each component of the substrate cleaning apparatus 100. The control program 162a includes a set of instructions for performing the cleaning process. However, the components constituting the control unit 160 are not limited to those shown in FIG1. For example, the control unit 160 may also include other components such as a large storage area device like a hard drive for storing various data, or a communication interface for communicating with an external network.

[0055] Hereinafter, the cleaning process (substrate cleaning method) performed by the substrate cleaning apparatus 100 described above will be described in detail.

[0056] [Operation of the substrate cleaning apparatus 100]

[0057] The substrate cleaning apparatus 100 of this embodiment cleans a substrate, which is an object, using a cryogenic cleaning method. In the substrate cleaning method of the first embodiment, the back side of the substrate W on which cleaning liquid is held is first cooled by using a cooling gas to freeze the liquid film on the surface of the substrate W (first cooling process). Then, the surface of the frozen film obtained by freezing the liquid film is cooled by using a cooling gas to further cool the frozen film held on the surface of the substrate W (second cooling process). In the substrate cleaning method of this embodiment, by directly cooling the surface of the frozen film, the temperature drop gradient (temperature drop rate) of the frozen film can be made larger than before, the time to lower the frozen film to the desired temperature can be shortened, and the throughput of the cleaning process can be increased.

[0058] FIG3 is a flowchart showing the structure of the substrate cleaning method performed by the substrate cleaning apparatus 100 of the first embodiment. The substrate cleaning method shown in FIG3 illustrates the process from the time the substrate W is brought in to the time the substrate W is taken out. FIG4 is a diagram illustrating the relationship between the operation of the substrate cleaning apparatus 100 of the first embodiment and the temperature of the cleaning fluid. In the timing diagram shown in the upper part of FIG4, the ON / OFF operation 40 of the liquid supply unit 140, the ON / OFF operation 20 of the first cooling medium supply unit 120, and the ON / OFF operation 30 of the second cooling medium supply unit 130 are shown. The temperature change of the cleaning fluid (pure water) over time is shown in the lower part of FIG4. In the graph shown in the lower part of FIG4, the horizontal axis is time and the vertical axis is temperature. Furthermore, in the graph shown in the lower part of FIG4, P1 to P4 represent the state of pure water. Specifically, P1 and P4 represent pure water as liquid phase. P2 represents pure water as a solid-liquid mixture (a state in which solid and liquid phases are mixed). P3 represents pure water as solid phase.

[0059] The following description of the substrate cleaning process is based on FIG3. FIG4 will be used as needed to describe the operation of the substrate cleaning apparatus 100 and the state of the water film or ice film maintained on the surface of the substrate W.

[0060] As shown in FIG3, when the cleaning process begins, the control unit 160 controls the first cooling medium supply unit 120 to supply cooling gas to the back side of the substrate W (step S001 in FIG3). Then, the control unit 160 controls the liquid supply unit 140 to supply pure water to the surface of the substrate W (step S002 in FIG3). At this time, the control unit 160 controls the rotation holding unit 110 to rotate the substrate W at a predetermined speed (e.g., approximately 100 rpm). Since pure water is supplied while the substrate W is rotating, the supplied pure water continues to be discharged to the outside of the substrate W.

[0061] Steps S001 and S002 are performed between time T0 and time T1 as shown in FIG. 4. In this embodiment, the process performed between time T0 and time T1 is called the "preparation process". As shown in the upper part of FIG. 4, at time T0, the liquid supply unit 140 and the first cooling medium supply unit 120 are in the on state. That is, in the preparation process, pure water is supplied to the surface of the substrate W while cooling the substrate W. When the substrate W is cooled, frost may sometimes form on the surface due to the temperature difference. In this case, there is a concern that particles floating in the chamber may be taken in by the frost and adhere to the surface of the substrate W. In this embodiment, in the preparation process, pure water is supplied to the surface side while cooling the substrate W from the back side, thus preventing frost from adhering to the surface of the substrate W. Furthermore, in FIG. 3, the order of steps S001 and S002 may be reversed, or they may be performed completely simultaneously.

[0062] When time T1 is reached, the control unit 160 controls the rotation holding unit 110 to reduce the rotation speed of the substrate W to a predetermined speed (e.g., about 30 rpm). Here, a predetermined amount of pure water is maintained on the surface of the substrate W, and a water film of predetermined thickness is formed on the surface of the substrate W. In this embodiment, the process performed between time T1 and time T2 is called the "water film formation process".

[0063] Next, the control unit 160 controls the liquid supply unit 140 to stop supplying pure water to the surface of the substrate W (step S003 in FIG3). Step S003 is executed at time T2 as shown in FIG4. As shown in the upper part of FIG4, at time T2, the liquid supply unit 140 is in the off state, while the first cooling medium supply unit 120 remains in the on state. In addition, as shown in the lower part of FIG4, when the supply of pure water from the liquid supply unit 140 is stopped, the temperature of the water film maintained on the surface of the substrate W decreases. Therefore, in this embodiment, the process executed between time T2 and time T6 is referred to as the "cooling process".

[0064] When the process is transferred to the cooling step, the control unit 160 controls the detection unit 132 to measure the temperature of the water film held on the surface of the substrate W. Specifically, in this embodiment, a radiation thermometer constituting the detection unit 132 is used to measure the temperature of the water film. Then, based on the detection results obtained by the detection unit 132, the control unit 160 determines whether the water film held on the surface of the substrate W is frozen, that is, whether an ice film (frozen body) has formed (step S004 in FIG3). As will be described later, a significant temperature change is observed when pure water changes from a liquid phase to a solid phase, therefore, by monitoring the temperature change of the water film, it is possible to detect whether an ice film has formed.

[0065] Here, the state change of pure water from time T2 to time T4 will be explained. As shown in the lower part of Figure 4, after time T2, the temperature of the water film remaining on the surface of the substrate W decreases, and soon becomes a supercooled state with a temperature below the freezing point (0°C in this embodiment). If the substrate W continues to cool after the water film becomes supercooled, the water film eventually leaves the supercooled state. In this embodiment, the supercooled state is removed at time T3 when the temperature drops to 5°C. However, the timing of removal from the supercooled state can be due to various factors such as stimulation caused by vibration or crystallization with foreign matter as a nucleus. After the pure water leaves the supercooled state, the temperature of the water film rises to 0°C and transforms into a state where the solid and liquid phases are mixed (solid-liquid mixed phase). The period of the solid-liquid mixed phase (between time T3 and time T4) is actually a very short period, so there is no substantial difference between time T3 and time T4.

[0066] In the cryo-cleaning method, it is generally believed that foreign matter becomes crystal nuclei and detaches from the supercooled state, beginning a transformation into the solid phase. In the case of this embodiment, foreign matter adhering to the surface of the substrate W becomes crystal nuclei and is frozen with pure water, thus the foreign matter is taken into the ice. Therefore, it is believed that in the solid-liquid mixed phase after detaching from the supercooled state, the ice containing the foreign matter is floating in a water film. That is, foreign matter such as particles adhering to the surface of the substrate W can be separated from the surface of the substrate W.

[0067] In step S004 of FIG3, the temperature rise of the water can be used to detect whether the pure water has escaped the supercooled state based on the detection result of the detection unit 132 (the measurement result of the water film temperature). That is, the determination result of the control unit 160 is "NO" until at least time T3 has elapsed. In step S004 shown in FIG3, when the determination result of the control unit 160 is "NO", the control unit 160 controls the detection unit 132 and repeats the determination periodically. Afterwards, the water film held on the surface of the substrate W is completely frozen to become an ice film through the solid-liquid mixed phase. When the water film held on the surface of the substrate W is completely frozen to become an ice film, the temperature of the ice film drops again (time T4). In this embodiment, when the temperature change of the above example is detected (that is, after the temperature rise when escaping the supercooled state, the temperature drops again), the determination result of the control unit 160 is "YES".

[0068] As shown in FIG3, when the determination result is "yes", the control unit 160 controls the second cooling medium supply unit 130 to supply cooling gas to the surface of the ice film held on the surface of the substrate W (step S005 in FIG3). Before the operation of the second cooling medium supply unit 130 begins, the blocking member 131 moves to a position close to the substrate W between time T2 and time T4. In the timing diagram shown in the upper part of FIG4, after a certain time interval from the time T4 when the ice film is formed, the determination result of the control unit 160 becomes "yes", and the second cooling medium supply unit 130 is turned on. As described above, in this embodiment, three radiation thermometers are used as detection units 132 to measure the temperature at different locations on the substrate W. In step S004 of FIG3, when a temperature drop is detected by all radiation thermometers, the control unit 160 outputs "yes" as a determination result. The time interval is the time from the formation of the ice film at time T4 until the measurement results of all radiation thermometers are consistent.

[0069] As shown in the lower part of FIG4, when cooling gas is supplied from the second cooling medium supply unit 130, the temperature of the ice film held on the surface of the substrate W is further reduced. In this embodiment, since the first cooling medium supply unit 120 is continuously on, the back side of the substrate W is continuously cooled. That is, the ice film held on the surface of the substrate W is continuously cooled from the back side via the substrate W. In addition, the ice film is also further cooled from the surface side directly by the cooling gas supplied from the second cooling medium supply unit 130. Therefore, compared with the case where cooling is only performed from the back side of the substrate W by the first cooling medium supply unit 120, the cooling of the ice film can be accelerated.

[0070] When cooling based on the second cooling medium supply unit 130 begins, the control unit 160 determines, based on the detection results obtained by the detection unit 132, whether the ice film held on the surface of the substrate W has reached a predetermined temperature (step S006 in FIG. 3). In this embodiment, the predetermined temperature is set to -20°C, but it is not limited to this example. In this embodiment, an example is shown of determining whether the temperature of the ice film has reached the predetermined temperature based on the measurement results of a radiation thermometer, but it is not limited to this example. For example, by using an imaging device as the detection unit 132 to photograph the surface state of the ice film and analyzing the photographed image, it is also possible to determine whether the temperature of the ice film has reached the predetermined temperature.

[0071] In step S006 shown in FIG3, if the determination result of the control unit 160 is "no", the control unit 160 controls the detection unit 132 and repeats the determination periodically. If the determination result of the control unit 160 is "yes", the control unit 160 disconnects the first cooling medium supply unit 120 and the second cooling medium supply unit 130, stopping the supply of cooling gas to the substrate W and the ice film (step S007 in FIG3). As shown in the upper part of FIG4, in this embodiment, at time T5, if the determination result of step S006 is "yes", the operation of the first cooling medium supply unit 120 and the second cooling medium supply unit 130 is stopped. In step S007, when the first cooling medium supply unit 120 and the second cooling medium supply unit 130 are disconnected, the supply of cooling gas stops, and therefore the temperature drop of the ice film stops. Afterwards, the temperature of the ice film gradually rises.

[0072] Next, the control unit 160 controls the liquid supply unit 140 to begin supplying pure water to the surface of the ice film (step S008 in FIG3). As shown in the upper part of FIG4, in this embodiment, after the first cooling medium supply unit 120 and the second cooling medium supply unit 130 are disconnected at time T5, a small time interval is allowed, and the liquid supply unit 140 is turned on at time T6. As described above, in this embodiment, when the operation of the second cooling medium supply unit 130 is stopped, the blocking member 131 is moved to a retracted position away from the substrate W. The time interval is the time until the liquid outlet 143a of the liquid supply unit 140 moves above the center of the substrate W (liquid supply position) after the blocking member 131 is moved to the retracted position.

[0073] When pure water is supplied from the liquid supply unit 140, the ice film held on the surface of the substrate W melts upon contact with the pure water. At this time, the control unit 160 controls the rotation holding unit 110 to rotate the substrate W at a predetermined speed (e.g., about 100 rpm). Since pure water is supplied while the substrate W is rotating, the supplied pure water, the melted ice film, and any foreign matter removed from the ice film are discharged to the outside of the substrate W. In this embodiment, the process performed between time T6 and time T7 is referred to as the "thawing process".

[0074] After the defrosting process begins and a predetermined time has elapsed, as shown in the upper part of FIG4, the control unit 160 controls the liquid supply unit 140 to be in a disconnected state, stopping the supply of pure water to the substrate W (step S009 in FIG3). In this embodiment, the liquid supply unit 140 is in a disconnected state at time T7.

[0075] Finally, the control unit 160 controls the rotation holding unit 110 to rotate the substrate W at a predetermined speed (e.g., 1500 rpm) to perform rotational drying (step S010 in FIG. 3). Once the substrate W is dry, the cleaning process is complete. The cleaning process described here can be repeated multiple times. By repeatedly performing the cleaning process described in this embodiment on the substrate W, which is the object to be cleaned, a further improvement in the cleaning effect can be achieved.

[0076] As explained above, in the cleaning process using the cryo-cleaning method based on this embodiment, an ice film is formed on the surface side by cooling from the back side of the substrate W. After the ice film is formed, cooling gas is supplied to the surface of the ice film to further cool it. According to this embodiment, by directly cooling the ice film formed on the surface to be processed (the surface to be cleaned) of the substrate W, the ice film can be cooled faster than by cooling only from the back side of the substrate. As a result, the time required to lower the ice film to the desired temperature can be shortened, increasing the throughput of the cleaning process. In addition, if cooling gas is supplied directly to the water film, which is a liquid, the water film may evaporate or be pushed and moved by the cooling gas, raising concerns that the thickness of the water film may become uneven or that part of the substrate W may be exposed. However, according to this embodiment, since cooling gas is not supplied to the water film before it becomes an ice film, an ice film can be formed uniformly on the substrate W.

[0077] (Modified Example 1)

[0078] In this embodiment, the following example is described: the detection unit 132 detects whether an ice film has formed, and based on the result, the second cooling medium supply unit 130 is turned on to cool the ice film. However, this embodiment is not limited to the above example. For example, it is also possible to experimentally determine in advance the time from stopping the supply of pure water to the formation of an ice film (i.e., the time from time T2 to time T4 shown in the lower part of FIG4), and turn on the second cooling medium supply unit 130 by time control.

[0079] Similarly, in this embodiment, the time from the start of cooling the ice film to cooling the ice film to a predetermined set temperature can be experimentally determined in advance (i.e., the time from time T4 to time T5 shown in the lower part of FIG4), and the first cooling medium supply unit 120 and the second cooling medium supply unit 130 are disconnected by time control.

[0080] According to this modified example, the detection unit 132 for detecting the state of the water film or ice film can be omitted, which simplifies the structure of the substrate cleaning apparatus 100. In addition, since it is not necessary to perform determination processes such as whether an ice film has formed or whether the ice film has reached a specified temperature, the control program 162a for performing the cleaning process can be further simplified.

[0081] (Modified Example 2)

[0082] In this embodiment, an example of having a blocking member 131 as the structure of the second cooling medium supply unit 130 has been described, but the embodiment is not limited to this example, and the blocking member 131 can be omitted. That is, as long as the ice film held on the surface of the substrate W can be cooled uniformly, the ice film can be cooled without using the blocking member 131. For example, multiple cooling gas outlets (supply nozzles) can be arranged facing the surface of the substrate W, so that cooling gas can be uniformly supplied to the surface of the ice film. In this case, the position of the first outlet for supplying cooling gas to the center of the substrate W is preferably offset relative to the rotation axis 11 so that the cooling gas does not touch the center position of the substrate W. In addition, the positions of the second outlets for supplying cooling gas to positions other than the center of the substrate W are preferably arranged equally around the first outlet.

[0083] The structure of the modified example 2 is described as a modification of the second cooling medium supply section 130, but similarly, the dispersion plate 122 can be omitted from the first cooling medium supply section 120. That is, even if the cooling gas flows along the upper surface (inclined surface 121aa) of the upper portion 121a of the nozzle head 121 or the upper surface of the inner portion 112a of the cover 112, the back side of the substrate W can be cooled uniformly. In addition, for example, multiple cooling gas outlets (supply nozzles) can be arranged facing the back side of the substrate W, so that cooling gas can be supplied uniformly to the back side of the substrate W. In this case, the position of the first outlet for supplying cooling gas to the center of the substrate W is preferably offset relative to the rotation axis 11 so that the cooling gas does not touch the center position of the substrate W. In addition, the positions of the second outlets for supplying cooling gas to positions other than the center of the substrate W are preferably arranged equally around the first outlet.

[0084] <Second Embodiment>

[0085] In the second embodiment, an example in which the cleaning process performed by the substrate cleaning apparatus 100 is configured differently from that in the first embodiment will be described. Specifically, the cleaning process in this embodiment differs from that in the first embodiment in that the operation of the first cooling medium supply unit 120 is stopped when the cooling process based on the second cooling medium supply unit 130 is performed. The basic structure of the substrate cleaning apparatus is the same as that of the substrate cleaning apparatus 100 described in the first embodiment. In addition, the basic structure of the substrate cleaning method in this embodiment is the same as that of the substrate cleaning method in the first embodiment, therefore, in the following description, the different parts will be described, and repeated descriptions will sometimes be omitted.

[0086] FIG5 is a flowchart showing the structure of the substrate cleaning method performed by the substrate cleaning apparatus 100 of the second embodiment. FIG6 is a diagram illustrating the relationship between the operation of the substrate cleaning apparatus 100 of the second embodiment and the temperature of the cleaning fluid. Regarding the contents of the figures shown in FIG5 and FIG6, except for the timing diagram shown in the upper part of FIG6, they are the same as those in FIG3 and FIG4 described in the first embodiment, and therefore the description is omitted. Specifically, in this embodiment, the structure of the operation 20a of the first cooling medium supply unit 120 in the timing diagram shown in the upper part of FIG6 is different from that in the first embodiment.

[0087] When the cleaning process begins, steps S001 to S005 shown in FIG5 are performed. That is, the control unit 160 turns on the second cooling medium supply unit 130 in order to form an ice film on the surface of the substrate W. These processes are the same as the processes S001 to S005 in FIG3 described in the first embodiment, so the description is omitted.

[0088] Furthermore, in this embodiment, the control unit 160 disconnects the first cooling medium supply unit 120 and stops supplying cooling gas to the back surface of the substrate W (step S006 in FIG. 5). That is, in this embodiment, after an ice film is formed on the surface of the substrate W, the indirect cooling process via the substrate W is switched to a direct cooling process on the surface of the ice film. As shown in the upper part of FIG. 6, in this embodiment, after a certain time interval from the time T4 when it is determined that an ice film has formed, the second cooling medium supply unit 130 is turned on and the first cooling medium supply unit 120 is turned off.

[0089] Subsequently, the ice film remaining on the surface of the substrate W cools down due to cooling provided by the second cooling medium supply section 130. At this time, since cooling on the back side of the substrate W stops, the temperature of the substrate W gradually increases. That is, after time T4, the temperature of the ice film decreases over time, and therefore the volume of the ice film shrinks. On the other hand, the temperature of the substrate W increases over time, and therefore the volume of the substrate W expands. Due to the difference in the state changes of the substrate W and the ice film, strain occurs at the contact surface between the two. If the strain increases, cracks will soon appear in the ice film.

[0090] In view of the above phenomenon, in this embodiment, when cooling based on the second cooling medium supply unit 130 begins, the control unit 160 determines, based on the detection result obtained by the detection unit 132, whether the ice film held on the surface of the substrate W has cracked (step S007 in FIG. 5). In this embodiment, the surface state of the ice film is photographed using an imaging device as the detection unit 132, and the photographed image is analyzed to determine whether cracks have occurred. However, it is not limited to the above example; other methods can be applied as long as cracks on the surface of the ice film can be detected.

[0091] In step S007 shown in FIG5, if the determination result of the control unit 160 is "no", the control unit 160 controls the detection unit 132 and repeats the determination periodically. If the determination result of the control unit 160 is "yes", the control unit 160 sets the second cooling medium supply unit 130 to the off state and stops supplying cooling gas to the ice film (step S008 in FIG5). In FIG5, the processing of steps S009 to S011 is the same as the processing of steps S008 to S010 in FIG3 described in the first embodiment, so the description is omitted.

[0092] As explained above, in the cleaning process using the cryo-cleaning method based on this embodiment, an ice film is formed on the surface side by cooling from the back side of the substrate W (first cooling process). After the ice film is formed, cooling gas is supplied to the surface of the ice film to further cool it (second cooling process). When cooling gas is supplied to the surface of the ice film, by stopping the cooling of the back side of the substrate W, strain is intentionally generated between the substrate W and the ice film, causing cracks to form in the ice film. When cracks form in the ice film, foreign objects taken into the ice film are further moved away from the surface of the substrate W, thus improving the efficiency of foreign object removal when removing the ice film. Therefore, even if the next process (ice film defrosting process) is entered at the time when the ice film cracks, as in this embodiment, foreign objects can be removed efficiently. Thus, according to this embodiment, by intentionally causing cracks in the ice film formed on the surface to be processed (the surface to be cleaned) of the substrate W, the time until entering the next process (defrosting process) can be significantly shortened, and the throughput of the cleaning process can be increased.

[0093] (Modified Example 1)

[0094] In this embodiment, the detection unit 132 is used to detect whether an ice film is formed. However, similar to the variation 1 of the first embodiment, the time from stopping the supply of pure water to the formation of an ice film can be experimentally determined in advance, and the second cooling medium supply unit 130 is turned on by time control.

[0095] In addition, in this embodiment, the following example is described: the detection unit 132 detects whether the ice film has cracked, and the second cooling medium supply unit 130 is disconnected based on the result. However, this embodiment is not limited to the above example. For example, it is also possible to experimentally determine in advance the time from the start of cooling of the ice film to the time when the ice film cracks (i.e., the time from time T4 to time T5 shown in the lower part of FIG6), and disconnect the second cooling medium supply unit 130 by time control.

[0096] According to this modified example, the detection unit 132 for detecting the state of the water film or ice film can be omitted, which simplifies the structure of the substrate cleaning apparatus 100. In addition, since it is not necessary to perform determination processes such as whether an ice film has formed or whether the ice film has cracked, the control program 162a for performing the cleaning process can be further simplified.

[0097] The substrate cleaning apparatus and substrate cleaning method according to one embodiment of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the described embodiments (including variations; the same applies below), and can be appropriately modified without departing from the spirit of the present invention. For example, solutions obtained by those skilled in the art based on appropriate additions, deletions, or design changes to constituent components in each embodiment are also included within the scope of the present invention as long as they possess the spirit of the present invention. Furthermore, the structures of each embodiment can be appropriately combined as long as they do not contradict each other, and common technical matters in each embodiment are included in each structure even if not explicitly stated.

[0098] Even if there are other effects that are different from the effects brought about by the various embodiments described, if they are effects that are clear according to the description in this specification or effects that can be easily predicted by those skilled in the art, they can of course be understood as effects brought about by the present invention. [Simplified Explanation of the Diagram]

[0009] FIG1 is a side view schematically showing the structure of the substrate cleaning apparatus of the first embodiment. FIG2 is a cross-sectional view schematically showing the structure of the main parts of the substrate cleaning apparatus of the first embodiment. FIG3 is a flowchart showing the structure of the substrate cleaning method performed by the substrate cleaning apparatus of the first embodiment. FIG4 is a diagram illustrating the relationship between the operation of the substrate cleaning apparatus of the first embodiment and the temperature of the cleaning solution. FIG5 is a flowchart showing the structure of the substrate cleaning method performed by the substrate cleaning apparatus of the second embodiment. FIG6 is a diagram illustrating the relationship between the operation of the substrate cleaning apparatus of the second embodiment and the temperature of the cleaning solution.

Claims

1. A substrate cleaning apparatus, comprising: The rotating holding part holds the substrate; A liquid supply unit supplies liquid to a first surface of the substrate; a first cooling medium supply unit supplies a first cooling medium to a second surface of the substrate opposite to the first surface; a second cooling medium supply unit supplies a second cooling medium to the first surface; and a control unit controls the rotation holding unit, the first cooling medium supply unit, the second cooling medium supply unit, and the liquid supply unit to perform a cleaning process on the substrate, the cleaning process including: a first cooling process, in which the liquid on the first surface is frozen to form a frozen body by supplying the first cooling medium to the second surface; The second cooling process further cools the cryogenic body by supplying the second cooling medium toward the first surface; and the melting process, after the second cooling process, melts the cryogenic body by supplying liquid to the cryogenic body through the liquid supply section.

2. The substrate cleaning apparatus as claimed in claim 1, wherein, During the second cooling process, the first cooling medium supply unit stops supplying the first cooling medium toward the second surface.

3. The substrate cleaning apparatus as described in claim 1 or 2, wherein, The melting process is performed in response to the occurrence of cracks in the frozen body during the second cooling process.

4. The substrate cleaning apparatus as described in claim 1 or 2, wherein, The second cooling medium supply unit includes a blocking member that is supported in a manner facing the first surface and is capable of being raised and lowered, through which the second cooling medium is supplied toward the first surface.

5. The substrate cleaning apparatus as claimed in claim 4, wherein, The blocking member is composed of a plate-shaped member having a through hole for supplying the second cooling medium.

6. The substrate cleaning apparatus as claimed in claim 4, wherein, The second cooling medium supply unit also includes a detection unit, which is installed on the blocking member to detect the formation of the freezer.

7. The substrate cleaning apparatus as claimed in claim 6, wherein, The detection unit is a radiation thermometer.

8. The substrate cleaning apparatus as described in claim 1 or 2, wherein, The first cooling medium and the second cooling medium are cooling media at the same temperature.

9. A substrate cleaning method, comprising: Liquid is supplied to a first surface of a substrate. A first cooling medium is supplied to a second surface of the substrate opposite to the first surface, causing the liquid on the first surface to freeze and form a frozen body. A second cooling medium is supplied to the first surface to further cool the frozen body. After the frozen body has been cooled, liquid is supplied to the frozen body to melt it.

10. The substrate cleaning method as described in claim 9, wherein, When further cooling the cryobody, the supply of the first cooling medium toward the second surface is stopped.

11. The substrate cleaning method as described in claim 9 or 10, wherein, The melting of the frozen body is performed when cracks are generated in the frozen body during the cooling process.

12. The substrate cleaning method as described in claim 9 or 10, wherein, The supply of the second cooling medium toward the first surface is performed in order to form the frozen body on the first surface.

13. The substrate cleaning method as described in claim 12, wherein, The formation of the cryogenic body is determined based on the results of measurements taken by a radiation thermometer.

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