Substrate processing apparatus

Abstract

To provide a substrate processing apparatus capable of improving a removal ratio of pollutant.SOLUTION: A substrate processing apparatus according to the present embodiment includes: a mounting board for supporting a substrate so that a cleaning surface of the substrate is turned to the underside in a gravity direction and capable of rotating the supported substrate; a cooling unit capable of supplying cooling gus from the upper side in the gravity direction to the surface opposite to the cleaning surface of the substrate; a first liquid supply unit capable of supplying first liquid from the underside in the gravity direction to the cleaning surface of the substrate; a second liquid supply unit capable of supplying second liquid from the upper side in the gravity direction to the surface opposite to the cleaning surface of the substrate; and a controller capable of controlling rotation of the substrate, supply of the cooling gas, supply of the first liquid, and supply of the second liquid.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a substrate processing apparatus.

Background Art

[0002] As a method for removing contaminants such as particles adhering to the surface of a substrate such as an imprint template, a photolithography mask, or a semiconductor wafer, a freeze cleaning method has been proposed.

[0003] In a general freeze cleaning method, first, a substrate is placed on a mounting table. At this time, the surface of the substrate on the side where freeze cleaning is to be performed (for example, the surface on which uneven portions serving as a pattern are formed) is oriented upward in the direction of gravity. Next, for example, when pure water is used as the liquid for cleaning, pure water and a cooling gas are supplied to the surface of the rotating substrate on the side where freeze cleaning is to be performed (hereinafter simply referred to as the cleaning surface). Next, the supply of pure water is stopped, and a part of the supplied pure water is discharged to form a water film on the cleaning surface of the substrate. The water film is frozen by the cooling gas supplied to the substrate. When the water film freezes to form an ice film, contaminants such as particles are incorporated into the ice film and separated from the cleaning surface of the substrate. Next, pure water is supplied to the ice film to melt the ice film, and the contaminants are removed from the cleaning surface of the substrate together with the pure water. (See, for example, Patent Document 1) If freeze cleaning is performed, contaminants can be efficiently removed from the cleaning surface of the substrate. However, in recent years, it has been desired to further improve the removal rate of contaminants.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide a substrate processing apparatus capable of improving the removal rate of contaminants.

Means for Solving the Problem

[0006] The substrate processing apparatus according to the embodiment includes a mounting table that supports the substrate with the cleaning surface of the substrate facing downward in the direction of gravity and is capable of rotating the supported substrate, a cooling unit capable of supplying a cooling gas from above in the direction of gravity to the surface of the substrate opposite to the cleaning surface, a first liquid supply unit capable of supplying a first liquid from below in the direction of gravity to the cleaning surface of the substrate, a second liquid supply unit capable of supplying a second liquid from above in the direction of gravity to the surface of the substrate opposite to the cleaning surface, a controller capable of controlling the rotation of the substrate, the supply of the cooling gas, the supply of the first liquid, and the supply of the second liquid, and is provided with 、 The controller controls the supply of the first liquid to continuously supply the first liquid to the cleaning surface of the substrate in a preliminary step of equalizing the in-plane temperature of the substrate, stop the supply of the first liquid in a liquid film forming step of forming a liquid film of the first liquid having a predetermined thickness on the cleaning surface of the substrate after the preliminary step, continue to stop the supply of the first liquid in a supercooling step of supercooling the liquid film of the first liquid on the cleaning surface of the substrate, continuously supply the first liquid to the cleaning surface of the substrate and continuously supply the second liquid to the surface opposite to the cleaning surface of the substrate in a thawing step of thawing the frozen liquid film of the first liquid after the supercooling step .

Effect of the Invention

[0007] According to the embodiment of the present invention, a substrate processing apparatus capable of improving the removal rate of contaminants is provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Best Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments will be exemplified with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and detailed descriptions thereof are omitted as appropriate. The substrate 100 exemplified below can be, for example, a semiconductor wafer, an imprint template, a photolithography mask, a plate-like body used for MEMS (Micro Electro Mechanical Systems), or the like.

[0010] Note that, on the cleaning surface of the substrate 100, uneven portions that are patterns may or may not be formed. A substrate on which uneven portions are not formed can be, for example, a substrate before the uneven portions are formed (for example, a so-called bulk substrate).

[0011] In the following, as an example, a case where the substrate 100 is a photolithography mask will be described. When the substrate 100 is a photolithography mask, the planar shape of the substrate 100 can be substantially rectangular.

[0012] FIG. 1 is a schematic diagram for exemplifying a substrate processing apparatus 1 according to the present embodiment. As shown in FIG. 1, the substrate processing apparatus 1 is provided with a mounting unit 2, a cooling unit 3, a first liquid supply unit 4, a second liquid supply unit 5, a housing 6, a blower unit 7, a detection unit 8, an exhaust unit 9, and a controller 10.

[0013] The mounting unit 2 includes a mounting table 2a, a rotating shaft 2b, and a driving unit 2c. The mounting table 2a can rotate the substrate 100. The mounting table 2a is rotatably provided inside the housing 6. The mounting table 2a has a plate shape. On one main surface of the mounting table 2a, a plurality of support portions 2a1 for supporting the substrate 100 are provided. When the substrate 100 is supported by the plurality of support portions 2a1, the cleaning surface 100b (the surface on the side where cryogenic cleaning is performed) of the substrate 100 faces the mounting table 2a side. For example, when uneven portions which are patterns are formed on one surface of the substrate 100, the surface on which the uneven portions are formed of the substrate 100 faces the mounting table 2a side. That is, the mounting table 2a supports the substrate 100 with the cleaning surface 100b of the substrate 100 facing downward in the gravitational direction.

[0014] The edges of the cleaning surface 100b of the substrate 100 contact the plurality of support portions 2a1. The portion of the support portion 2a1 that contacts the edge of the cleaning surface 100b can be a tapered surface or an inclined surface. If the portion of the support portion 2a1 that contacts the edge of the cleaning surface 100b is a tapered surface, point contact can be made between the support portion 2a1 and the edge of the cleaning surface 100b. If the portion of the support portion 2a1 that contacts the edge of the cleaning surface 100b is an inclined surface, line contact can be made between the support portion 2a1 and the edge of the cleaning surface 100b. If point contact or line contact is made between the support portion 2a1 and the edge of the cleaning surface 100b, generation of dirt, damage, etc. on the substrate 100 can be suppressed.

[0015] In addition, a hole 2aa penetrating in the thickness direction of the mounting table 2a is provided in the central portion of the mounting table 2a.

[0016] One end portion of the rotating shaft 2b is fitted into the hole 2aa of the mounting table 2a. The other end portion of the rotating shaft 2b is provided outside the housing 6. The rotating shaft 2b is connected to a drive portion 2c outside the housing 6.

[0017] The rotating shaft 2b has a cylindrical shape. The end portion of the rotating shaft 2b on the mounting table 2a side may be open or closed.

[0018] At the end of the rotating shaft 2b opposite to the mounting table 2a side, a pipe connecting a flow control unit 4c and a liquid nozzle 4d, which will be described later, is attached. A rotary shaft seal (not shown) is provided between the end of the rotary shaft 2b opposite to the mounting table 2a side and the pipe. Therefore, the end of the rotary shaft 2b opposite to the mounting table 2a side is sealed to be airtight.

[0019] The drive unit 2c is provided outside the housing 6. The drive unit 2c is connected to the rotary shaft 2b. The drive unit 2c has a rotating device such as a motor. The rotational force of the drive unit 2c is transmitted to the mounting table 2a via the rotary shaft 2b. Therefore, the drive unit 2c can rotate the mounting table 2a, and thus the substrate 100 placed on the mounting table 2a.

[0020] In addition, the drive unit 2c can change not only the start and stop of rotation but also the rotation speed (rotational speed). In this case, the drive unit 2c can be provided with a control motor such as a servo motor, for example.

[0021] The cooling unit 3 supplies the cooling gas 3a1 from the upper side in the gravitational direction to the surface 100a of the substrate 100 opposite to the cleaning surface 100b (hereinafter simply referred to as the back surface 100a). The cooling unit 3 has, for example, a coolant unit 3a, a filter 3b, a flow control unit 3c, and a cooling nozzle 3d. The coolant unit 3a, the filter 3b, and the flow control unit 3c are provided outside the housing 6.

[0022] The coolant unit 3a stores the coolant and generates the cooling gas 3a1. The coolant is the liquefied cooling gas 3a1. The cooling gas 3a1 is not particularly limited as long as it is a gas that hardly reacts with the material of the substrate 100. The cooling gas 3a1 can be, for example, an inert gas such as nitrogen gas, helium gas, or argon gas.

[0023] In this case, if a gas with a high specific heat is used, the cooling time of the substrate 100 can be shortened. For example, if helium gas is used, the cooling time of the substrate 100 can be shortened. Also, if nitrogen gas is used, the processing cost of the substrate 100 can be reduced.

[0024] The coolant section 3a includes a tank for storing the coolant and a vaporizing section for vaporizing the coolant stored in the tank. A cooling device for maintaining the temperature of the coolant is provided in the tank. The vaporizing section raises the temperature of the coolant to generate the cooling gas 3a1 from the coolant. The vaporizing section can utilize, for example, the outside air temperature or heating by a heat medium. The temperature of the cooling gas 3a1 may be a temperature below the freezing point of the liquid 101 (corresponding to an example of the first liquid), and can be, for example, -170°C.

[0025] The filter 3b is connected to the coolant section 3a via a pipe. The filter 3b suppresses contaminants such as particles contained in the coolant from flowing out to the substrate 100 side.

[0026] The flow rate control section 3c is connected to the filter 3b via a pipe. The flow rate control section 3c controls the flow rate of the cooling gas 3a1. The flow rate control section 3c can be, for example, an MFC (Mass Flow Controller) or the like. Also, the flow rate control section 3c may indirectly control the flow rate of the cooling gas 3a1 by controlling the supply pressure of the cooling gas 3a1. In this case, the flow rate control section 3c can be, for example, an APC (Auto Pressure Controller) or the like.

[0027] The temperature of the cooling gas 3a1 generated from the coolant in the coolant section 3a is substantially at a predetermined temperature. Therefore, by controlling the flow rate of the cooling gas 3a1 by the flow rate control section 3c, the temperature of the substrate 100, and thus the temperature of the liquid 101 on the cleaning surface 100b of the substrate 100, can be controlled. For example, by controlling the flow rate of the cooling gas 3a1 by the flow rate control section 3c, a supercooled state of the liquid 101 can be caused in the supercooling process described later.

[0028] The cooling nozzle 3d is provided above the substrate 100 in the direction of gravity. The cooling nozzle 3d has a cylindrical shape. One end of the cooling nozzle 3d is connected to the flow rate control unit 3c via a pipe. The pipe connecting the cooling nozzle 3d and the flow rate control unit 3c is connected to a horizontally extending arm (not shown) that supports the cooling nozzle 3d. The arm (not shown) rotates about an end on the side opposite to the cooling nozzle 3d as a fulcrum. Therefore, the cooling nozzle 3d reciprocates (oscillates) along an arc-shaped locus between the central portion and the outer peripheral side of the mounting table 2a. A discharge port is provided at the other end of the cooling nozzle 3d. When the cooling nozzle 3d moves along an arc-shaped locus toward the central portion of the mounting table 2a, the discharge port faces the back surface 100a of the substrate 100.

[0029] The cooling nozzle 3d supplies the cooling gas 3a1 whose flow rate is controlled by the flow rate control unit 3c to the substrate 100. The cooling gas 3a1 discharged from the discharge port of the cooling nozzle 3d is directly supplied to the back surface 100a of the substrate 100.

[0030] The first liquid supply unit 4 supplies the liquid 101 to the cleaning surface 100b of the substrate 100 from below in the direction of gravity. In the freezing process (solid-liquid phase) described later, when the liquid 101 changes to a solid, its volume changes, so a pressure wave is generated. It is considered that the contaminants adhering to the cleaning surface 100b of the substrate 100 are separated by this pressure wave. Therefore, the liquid 101 is not particularly limited as long as it is difficult to react with the material of the substrate 100.

[0031] However, if the liquid 101 is a liquid whose volume increases when frozen, it is also considered that the physical force associated with the volume increase can be used to separate the contaminants adhering to the cleaning surface of the substrate 100. Therefore, the liquid 101 is preferably a liquid that is difficult to react with the material of the substrate 100 and whose volume increases when frozen. For example, the liquid 101 can be water (e.g., pure water, ultrapure water, etc.) or a liquid mainly composed of water.

[0032] The liquid mainly composed of water can be, for example, a mixture of water and alcohol, a mixture of water and an acidic solution, a mixture of water and an alkaline solution, etc. If it is a mixture of water and alcohol, the surface tension can be reduced, so it becomes easy to supply the liquid 101 into the fine concavo-convex portions formed on the cleaning surface 100b of the substrate 100.

[0033] If it is a mixture of water and an acidic solution, contaminants such as particles and resist residues attached to the cleaning surface 100b of the substrate 100 can be dissolved. For example, if it is a mixture of water and sulfuric acid, etc., contaminants composed of resist and metal can be dissolved. If it is a mixture of water and an alkaline solution, the zeta potential can be reduced, so it is possible to suppress the reattachment of the contaminants separated from the cleaning surface 100b of the substrate 100 to the cleaning surface 100b of the substrate 100.

[0034] However, if the components other than water become too much, it becomes difficult to utilize the physical force accompanying the volume increase, so there is a possibility that the removal rate of contaminants decreases. Therefore, the concentration of the components other than water is preferably 5 wt% or more and 30 wt% or less.

[0035] Also, a gas can be dissolved in the liquid 101. The gas can be, for example, carbon dioxide gas, ozone gas, hydrogen gas, etc. If carbon dioxide gas is dissolved in the liquid 101, the conductivity of the liquid 101 can be increased, so static elimination and antistatic of the substrate 100 can be performed. If ozone gas is dissolved in the liquid 101, contaminants composed of organic substances can be dissolved.

[0036] The first liquid supply unit 4 has, for example, a liquid storage unit 4a, a supply unit 4b, a flow rate control unit 4c, and a liquid nozzle 4d. The liquid storage unit 4a, the supply unit 4b, and the flow rate control unit 4c are provided outside the housing 6.

[0037] The liquid storage part 4a stores the aforementioned liquid 101. The liquid 101 is stored in the liquid storage part 4a at a temperature higher than the freezing point. The liquid 101 is stored, for example, at room temperature (20°C).

[0038] The supply part 4b is connected to the liquid storage part 4a via a pipe. The supply part 4b supplies the liquid 101 stored in the liquid storage part 4a toward the liquid nozzle 4d. The supply part 4b can be, for example, a pump having resistance to the liquid 101. Although the case where the supply part 4b is a pump is exemplified, the supply part 4b is not necessarily limited to a pump. For example, the supply part 4b may supply gas into the liquid storage part 4a and pump the liquid 101 stored in the liquid storage part 4a.

[0039] The flow rate control part 4c is connected to the supply part 4b via a pipe. The flow rate control part 4c controls the flow rate of the liquid 101 supplied by the supply part 4b. The flow rate control part 4c can be, for example, a flow rate control valve. Also, the flow rate control part 4c can also start and stop the supply of the liquid 101.

[0040] The liquid nozzle 4d is provided inside the housing 6. The liquid nozzle 4d is provided on the lower side in the gravitational direction of the substrate 100. One end of the liquid nozzle 4d is connected to the flow rate control part 4c via a pipe. The other end of the liquid nozzle 4d (the discharge port of the liquid 101) faces the cleaning surface 100b of the substrate 100 placed on the mounting table 2a. Also, the other end of the liquid nozzle 4d is located substantially at the center of the cleaning surface 100b of the substrate 100.

[0041] The liquid 101 discharged from the liquid nozzle 4d is supplied to the cleaning surface 100b of the substrate 100. At this time, the liquid nozzle 4d is sealed with the end of the rotating shaft 2b on the mounting table 2a side through a rotating shaft seal (not shown), for example, so that the liquid 101 that has fallen from the cleaning surface 100b of the substrate 100 does not enter the inside of the rotating shaft 2b. Alternatively, when the end of the rotating shaft 2b on the mounting table 2a side is open, the other end of the liquid nozzle 4d is preferably larger than the end of the rotating shaft 2b on the mounting table 2a side so that the liquid 101 does not enter the inside of the rotating shaft 2b. It is preferable that the liquid 101 discharged from the liquid nozzle 4d is supplied to a wider area of the cleaning surface 100b. Therefore, the liquid nozzle 4d can be, for example, a single-fluid nozzle capable of diffusing and ejecting the liquid so as to supply the liquid to a wide range (the entire cleaning surface of the substrate). That is, the first liquid supply unit 4 can have a single-fluid nozzle provided on the lower side in the gravitational direction of the substrate 100.

[0042] The liquid 101 discharged from the liquid nozzle 4d adheres to the cleaning surface 100b of the substrate 100. The liquid 101 adhering to the cleaning surface 100b spreads toward the periphery of the substrate 100 as the substrate 100 rotates. Therefore, a film of the liquid 101 having a substantially constant thickness is formed on the cleaning surface 100b of the substrate 100. Hereinafter, the film of the liquid 101 formed on the cleaning surface 100b of the substrate 100 will be referred to as a liquid film.

[0043] The second liquid supply unit 5 supplies the liquid 102 (corresponding to an example of the second liquid) to the back surface 100a of the substrate 100 from the upper side in the gravitational direction. The second liquid supply unit 5 has, for example, a liquid storage unit 5a, a supply unit 5b, a flow rate control unit 5c, and a liquid nozzle 5d. The liquid storage unit 5a, the supply unit 5b, and the flow rate control unit 5c are provided outside the housing 6.

[0044] Liquid 102 is used in the back surface cleaning process described later. Therefore, Liquid 102 is not particularly limited as long as it hardly reacts with the material of the substrate 100 and hardly remains on the back surface 100a of the substrate 100 in the drying process described later. Liquid 102 can be, for example, water (e.g., pure water, ultrapure water, etc.) or a mixture of water and alcohol. The temperature of Liquid 102 is not particularly limited. The temperature of Liquid 102 can be, for example, about room temperature (20 °C).

[0045] The liquid storage part 5a can be the same as the liquid storage part 4a described above. The supply part 5b can be the same as the supply part 4b described above. The flow rate control part 5c can be the same as the flow rate control part 4c described above.

[0046] When Liquid 102 and Liquid 101 are the same, the liquid storage part 4a and the supply part 4b may be shared by the first liquid supply part 4 and the second liquid supply part 5.

[0047] The liquid nozzle 5d is provided inside the housing 6. The liquid nozzle 5d is provided above the substrate 100 in the direction of gravity. The liquid nozzle 5d has a cylindrical shape. One end of the liquid nozzle 5d is connected to the flow rate control part 5c via a pipe. The other end of the liquid nozzle 5d faces the back surface 100a of the substrate 100 placed on the mounting table 2a. The other end of the liquid nozzle 5d is the discharge port of Liquid 102. Therefore, the Liquid 102 discharged from the liquid nozzle 5d is supplied to the back surface 100a of the substrate 100.

[0048] Also, the pipe connecting the liquid nozzle 5d and the flow control unit 5c is, for example, a flexible tube. The flexible tube is connected to a horizontally extending arm (not shown) that supports the liquid nozzle 5d. The arm (not shown) rotates about an end on the side opposite to the liquid nozzle 5d as a fulcrum. Therefore, the liquid nozzle 5d reciprocates (oscillates) along an arcuate locus between the central portion and the outer peripheral side of the mounting table 2a. When the other end of the liquid nozzle 5d moves along the arcuate locus toward the central portion of the mounting table 2a, it is positioned substantially at the center of the back surface 100a of the substrate 100. The liquid 102 discharged from the liquid nozzle 5d spreads from substantially the center of the back surface 100a of the substrate 100 and is discharged from the periphery of the back surface 100a of the substrate 100.

[0049] The housing 6 has a box shape. A cover 6a is provided inside the housing 6. The cover 6a receives the liquids 101 and 102 that are supplied to the substrate 100 and discharged to the outside of the substrate 100 as the substrate 100 rotates. The cover 6a has a cylindrical shape. The vicinity of the end of the cover 6a on the side opposite to the mounting table 2a side (near the upper end of the cover 6a) is bent toward the center of the cover 6a. Therefore, it is possible to facilitate the capture of the liquids 101 and 102 that splash above the substrate 100.

[0050] Also, a partition plate 6b is provided inside the housing 6. The partition plate 6b is provided between the outer surface of the cover 6a and the inner surface of the housing 6.

[0051] A plurality of discharge ports 6c are provided on the side surface on the bottom side of the housing 6. In the case of the housing 6 illustrated in FIG. 1, two discharge ports 6c are provided. The used cooling gas 3a1, air 7a, liquid 101, and liquid 102 are discharged from the discharge ports 6c to the outside of the housing 6.

[0052] The discharge ports 6c are provided below the substrate 100. Therefore, a downflow is created when the cooling gas 3a1 is exhausted from the discharge ports 6c. As a result, it is possible to prevent the particles from rising.

[0053] In a plan view, the plurality of discharge ports 6c are provided symmetrically with respect to the center of the housing 6. In this way, with respect to the center of the housing 6, the exhaust directions of the cooling gas 3a1 are symmetric. If the exhaust directions of the cooling gas 3a1 are symmetric, the exhaust of the cooling gas 3a1 becomes smooth.

[0054] The blower unit 7 is provided on the ceiling surface of the housing 6. Note that the blower unit 7 can also be provided on the side surface of the housing 6 as long as it is on the ceiling side. The blower unit 7 can include a blower such as a fan and a filter. The filter can be, for example, a HEPA filter (High Efficiency Particulate Air Filter) or the like.

[0055] The blower unit 7 supplies air 7a (outside air) to the space between the partition plate 6b and the ceiling of the housing 6. Therefore, the pressure in the space between the partition plate 6b and the ceiling of the housing 6 becomes higher than the external pressure. As a result, it becomes easy to guide the air 7a supplied by the blower unit 7 to the discharge port 6c. Also, it is possible to suppress contaminants such as particles from entering the inside of the housing 6 from the discharge port 6c.

[0056] Also, the blower unit 7 can supply dry room-temperature air 7a to the substrate 100. Therefore, the blower unit 7 can also promote the drying of the liquids 101 and 102 in the drying process described later.

[0057] The detection unit 8 is provided inside the housing 6. The detection unit 8 detects, for example, the temperature of the liquid film (liquid 101), the temperature of the film in which the frozen liquid 101 and the liquid 101 are mixed, and the temperature of the frozen liquid 101 (frozen film). In this case, the detection unit 8 can be, for example, a radiation thermometer, a thermoviewer, a thermocouple, or a resistance thermometer. Also, the detection unit 8 may be configured to detect the thickness of the film or the surface position of the film. In this case, the detection unit 8 can be, for example, a laser displacement meter, an ultrasonic displacement meter, or the like. Also, the detection unit 8 may be an optical sensor, an image sensor, or the like that detects the surface state of the film.

[0058] For example, the detected temperature, thickness, and surface state of the liquid film can be used to control the supercooled state of the liquid 101 in the supercooling process described later. Note that controlling the supercooled state means controlling the curve of the temperature change of the liquid 101 in the supercooled state so that the liquid 101 is not frozen by being rapidly cooled, that is, the supercooled state is maintained.

[0059] For example, the detected temperature, thickness, and surface state of the frozen film can be used to detect the occurrence of cracks in the frozen film (hereinafter referred to as "occurrence of cracks") in the freezing process (solid phase) described later. For example, when the detection unit 8 detects temperature, the occurrence of cracks can be indirectly detected from the temperature of the frozen film in the freezing process (solid phase) described later. When the detection unit 8 detects thickness, the occurrence of cracks can be detected from the change in the surface position of the frozen film in the freezing process (solid phase) described later. When the detection unit 8 detects the surface state, the occurrence of cracks can be detected from the surface state of the frozen film in the freezing process (solid phase) described later. Details regarding cracks will be described later.

[0060] The exhaust unit 9 is connected to the exhaust port 6c via the exhaust pipe 6c1. The exhaust unit 9 discharges the used cooling gas 3a1 and air 7a to the outside of the housing 6. The exhaust unit 9 can be, for example, a pump or a blower. Note that the used liquids 101 and 102 are discharged to the outside of the housing 6 via the discharge pipe 6c2 connected to the exhaust pipe 6c1.

[0061] The controller 10 controls the operations of the respective elements provided in the substrate processing apparatus 1. For example, the controller 10 can control the rotation of the substrate 100, the supply of the cooling gas 3a1, the supply of the liquid 101, and the supply of the liquid 102. The controller 10 has, for example, an arithmetic unit such as a CPU (Central Processing Unit) and a storage unit such as a semiconductor memory. The controller 10 is, for example, a computer. The storage unit can store a control program for controlling the operations of the respective elements provided in the substrate processing apparatus 1. The arithmetic unit controls the operations of the respective elements provided in the substrate processing apparatus 1 using the control program stored in the storage unit, data input by the operator, data from the detection unit 8, and the like.

[0062] For example, the cooling rate of the liquid 101 is correlated with the thickness of the liquid film. For example, the thinner the liquid film, the faster the cooling rate of the liquid 101. Conversely, the thicker the liquid film, the slower the cooling rate of the liquid 101. Therefore, the controller 10 can control the flow rate of the cooling gas 3a1, and thus the cooling rate of the liquid 101, based on the thickness of the liquid 101 (the thickness of the liquid film) detected by the detection unit 8. Note that the control of the temperature and cooling rate of the liquid 101 is performed, for example, when controlling the supercooled state of the liquid 101 in the supercooling process described later.

[0063] Therefore, for example, the controller 10 controls at least one of the rotation speed of the substrate 100, the flow rate of the cooling gas 3a1, and the supply amount of the liquid 101 so that the liquid 101 on the cleaning surface 100b of the substrate 100 is in a supercooled state.

[0064] Next, an example of the operation of the substrate processing apparatus 1 will be given. FIG. 2 is a timing chart for exemplifying the operation of the substrate processing apparatus 1. FIG. 3 is a graph for exemplifying the temperature change of the liquid 101 supplied to the substrate 100. Note that FIGS. 2 and 3 show the case where the substrate 100 is a 6025 quartz (Qz) substrate (152 mm × 152 mm × 6.35 mm) and the liquids 101 and 102 are pure water.

[0065] First, the substrate 100 is carried into the housing 6 through a loading / unloading port (not shown) of the housing 6. The loaded substrate 100 is placed and supported on a plurality of support portions 2a1 of the mounting table 2a. At this time, the cleaning surface 100b of the substrate 100 is oriented toward the mounting table 2a side (the lower side in the direction of gravity). For example, the substrate 100 is transported by a transport robot (not shown) equipped with a mechanism for reversing the orientation of the substrate 100. Alternatively, a reversing unit equipped with a mechanism for reversing the orientation of the substrate 100 is provided outside the housing 6.

[0066] After the substrate 100 is supported by the mounting table 2a, a freezing cleaning process including a preliminary process, a liquid film forming process, a cooling process, a thawing process, a back surface cleaning process, and a drying process is performed as shown in FIG. 2.

[0067] First, as shown in FIGS. 2 and 3, the preliminary process is executed. In the preliminary process, the controller 10 controls the supply unit 4b and the flow rate control unit 4c to supply a liquid 101 at a predetermined flow rate to the cleaning surface 100b of the substrate 100. Further, the controller 10 controls the flow rate control unit 3c to supply a cooling gas 3a1 at a predetermined flow rate to the back surface 100a of the substrate 100. Further, the controller 10 controls the drive unit 2c to rotate the substrate 100 at a third rotational speed.

[0068] Here, when the atmosphere in the housing 6 is cooled by the supply of the cooling gas 3a1 by the cooling unit 3, frost containing dust in the atmosphere may adhere to the substrate 100, which may cause contamination. In the preliminary process, since the liquid 101 is continuously supplied to the cleaning surface 100b of the substrate 100, it is possible to prevent the adhesion of frost to the cleaning surface 100b of the substrate 100 while uniformly cooling the substrate 100. Further, since the cleaning surface 100b of the substrate 100 faces the lower side in the direction of gravity, it is possible to more reliably prevent the adhesion of frost to the cleaning surface 100b of the substrate 100.

[0069] In the case illustrated in FIG. 2, the third rotation speed of the substrate 100 is, for example, about 50 rpm to 500 rpm. Also, the flow rate of the liquid 101 is, for example, about 0.1 L / min to 1.0 L / min. Further, the flow rate of the cooling gas 3a1 is, for example, about 40 NL / min to 200 NL / min. Also, the process time of the preliminary process is, for example, about 1800 seconds. Note that the process time of the preliminary process may be a time when the in-plane temperature of the substrate 100 becomes substantially uniform, and can be obtained by performing experiments or simulations in advance.

[0070] In the preliminary process, the temperature of the liquid film is almost the same as the temperature of the supplied liquid 101 because the liquid 101 is in a flowing-over state. For example, when the temperature of the supplied liquid 101 is about room temperature (20 °C), the temperature of the liquid film is about room temperature (20 °C).

[0071] Next, as shown in FIGS. 2 and 3, a liquid film forming process is executed. In the liquid film forming process, the controller 10 controls the drive unit 2c to rotate the substrate 100 at the second rotation speed.

[0072] Here, if the thickness of the liquid film is made too thin, it becomes difficult to remove contaminants. Also, since the cleaning surface 100b of the substrate 100 faces downward in the gravitational direction, if the thickness of the liquid film is made too thick, the in-plane distribution of the liquid film thickness becomes large. When the in-plane distribution of the liquid film thickness becomes large, the in-plane distribution of the contaminant removal rate becomes large.

[0073] In this case, if the thickness of the liquid film is set to 20 μm or more and 500 μm or less, the in-plane distribution of the liquid film thickness can be reduced, and thus the in-plane distribution of the contaminant removal rate can be reduced. For example, the controller 10 controls at least one of the rotation speed of the substrate 100 and the supply amount of the liquid 101 to make the thickness of the liquid film (film of the liquid 101) on the cleaning surface 100b of the substrate 100 be 20 μm or more and 500 μm or less. In this case, if the second rotation speed is 100 rpm or more and 300 rpm or less, it becomes easy to make the thickness of the liquid film be 20 μm or more and 500 μm or less. That is, the controller 10 rotates the substrate 100 at the same rotation speed as that during the preliminary process or at a rotation speed lower than that during the preliminary process.

[0074] In the liquid film forming process, for example, as shown in FIG. 2, the supply of the liquid 101 supplied during the preliminary process is stopped, and the substrate 100 is rotated at the second rotation speed until it reaches a predetermined thickness. Whether it has reached the predetermined thickness may be confirmed by measuring the thickness of the liquid film with the detection unit 8. The thickness of the liquid film may be measured by the detection unit 8, and the second rotation speed may be maintained for a time from the measured thickness to the predetermined thickness calculated in advance.

[0075] Thereafter, the rotation speed of the substrate 100 is set to the first rotation speed. The first rotation speed is a rotation speed at which the liquid film formed on the cleaning surface 100b of the substrate 100 is maintained at a uniform thickness. The first rotation speed may be any rotation speed that can suppress the variation in the thickness of the liquid film due to centrifugal force. For example, it may be about 0 rpm to 50 rpm.

[0076] Note that the flow rate of the cooling gas 3a1 in the liquid film forming process is the same as that in the preliminary process. As described above, in the preliminary process, the in-plane temperature of the substrate 100 is made substantially uniform. By maintaining the flow rate of the cooling gas 3a1 in the liquid film forming process to be the same as that in the preliminary process, the state where the in-plane temperature of the substrate 100 is substantially uniform can be maintained.

[0077] Also, when it is desired to increase the thickness of the liquid film, it is also possible to set it to the first rotation speed without changing from the third rotation speed to the second rotation speed. In this case, the first rotation speed is preferably a rotation speed close to 0 rpm. Note that the rotation speed in the preliminary process and the liquid film formation process may be the first rotation speed. Also, the third rotation speed may be slower than the first rotation speed.

[0078] Also, when transitioning from the preliminary process to the liquid film formation process, the liquid 101 supplied in the preliminary process may be discharged by rotating the substrate 100 at a high speed. In this case, after discharging the liquid 101, the rotation speed of the substrate 100 may be set as the second rotation speed, and a predetermined amount of the liquid 101 may be supplied to the cleaning surface 100b of the substrate 100. By doing so, a liquid film having a predetermined thickness can be easily formed.

[0079] Next, as shown in FIGS. 2 and 3, a cooling process is executed. In the present embodiment, among the cooling process, the period until before the freezing of the supercooled liquid 101 starts is referred to as the "supercooling process", the period from when the freezing of the supercooled liquid 101 starts until before the freezing is completely completed is referred to as the "freezing process (solid-liquid phase)", and the process of further cooling the frozen liquid 101 is referred to as the "freezing process (solid phase)".

[0080] For example, in the supercooling process, only the liquid 101 exists on the cleaning surface 100b of the substrate 100. For example, in the freezing process (solid-liquid phase), both the liquid 101 and the frozen liquid 101 exist on the cleaning surface 100b of the substrate 100. For example, in the freezing process (solid phase), only the frozen liquid 101 exists on the cleaning surface 100b of the substrate 100. Note that the solid-liquid phase means a state in which both the liquid 101 and the frozen liquid 101 are present as a whole. Also, the state in which only the frozen liquid 101 remains is called the frozen film 101a.

[0081] First, in the supercooling process, the temperature of the liquid film formed on the cleaning surface 100b is further lowered than the temperature of the liquid film in the liquid film formation process by the cooling gas 3a1 continuously supplied to the back surface 100a of the substrate 100, and a supercooled state is achieved.

[0082] Here, if the cooling rate of the liquid 101 is too high, the liquid 101 will not enter a supercooled state and will freeze immediately. Therefore, the controller 10 controls at least one of the rotation speed of the substrate 100, the flow rate of the cooling gas 3a1, and the supply amount of the liquid 101 so that the liquid 101 on the cleaning surface 100b of the substrate 100 enters a supercooled state.

[0083] The control conditions for the liquid 101 to enter a supercooled state are affected by factors such as the size of the substrate 100, the viscosity of the liquid 101, and the specific heat of the cooling gas 3a1. Therefore, it is preferable to appropriately determine the control conditions for the liquid 101 to enter a supercooled state through experiments or simulations.

[0084] In the supercooled state, for example, due to factors such as the temperature of the liquid film, the presence of contaminants such as particles and bubbles, and vibration, the freezing of the liquid 101 starts. For example, when there are contaminants such as particles, the freezing of the liquid 101 starts when the temperature T of the liquid 101 is -35°C or higher and -20°C or lower. Also, by applying vibration to the liquid 101, such as by varying the rotation speed of the substrate 100, the freezing of the liquid 101 can be started.

[0085] When the freezing of the supercooled liquid 101 starts, it transitions from the supercooling process to the freezing process (solid-liquid phase). In the supercooled liquid 101, a certain proportion of the starting point of freezing becomes contaminants. It is considered that the contaminants become the starting point of freezing, a pressure wave is generated due to the volume change when the liquid 101 changes to a solid, and a physical force is generated due to the volume increase, causing the contaminants attached to the cleaning surface 100b of the substrate 100 to be separated.

[0086] Also, as described above, since the cleaning surface 100b of the substrate 100 faces downward in the gravitational direction, gravity makes it easier for the contaminants attached to the cleaning surface 100b to be separated.

[0087] That is, in the case of the substrate processing apparatus 1 according to the present embodiment, contaminants adhering to the cleaning surface 100b of the substrate 100 can be separated by the pressure wave and physical force generated when a part of the liquid 101 freezes, and gravity. Therefore, the removal rate of contaminants can be improved.

[0088] In the freezing process (solid-liquid phase), the liquid film does not freeze instantaneously. In the freezing process (solid-liquid phase), the liquid 101 and the frozen liquid 101 exist on the entire cleaning surface 100b of the substrate 100.

[0089] When the liquid 101 freezes, latent heat is generated. By releasing the latent heat, the temperature of the frozen liquid 101 rises to the freezing point.

[0090] Even in the freezing process (solid-liquid phase), the cooling gas 3a1 is supplied to the back surface 100a of the substrate 100. For this reason, the generation rate of latent heat and the cooling rate are balanced, and the temperature is kept constant at a temperature slightly lower than the freezing point. When the liquid film is completely frozen and the frozen film 101a is formed, the generation of latent heat stops. On the other hand, the supply of the cooling gas 3a1 to the back surface 100a of the substrate 100 is maintained. Therefore, when the frozen film 101a is formed, the temperature of the frozen film 101a begins to decrease.

[0091] When the liquid film on the cleaning surface 100b of the substrate 100 is completely frozen, the freezing process (solid-liquid phase) shifts to the freezing process (solid phase). As described above, in the freezing process (solid phase), the temperature of the frozen film 101a on the cleaning surface 100b of the substrate 100 further decreases.

[0092] Here, the liquid 101 mainly contains water. Therefore, when the liquid film on the cleaning surface 100b of the substrate 100 is completely frozen to form the frozen film 101a and the temperature of the frozen film 101a further decreases, the volume of the frozen film 101a shrinks and stress is generated in the frozen film 101a. In this case, when the temperature of the frozen film becomes -50°C or lower, the frozen film 101a cracks because it cannot withstand the increased stress.

[0093] When cracks occur in the freezing film 101a, contaminants adhering to the cleaning surface 100b of the substrate 100 are separated from the cleaning surface 100b. The mechanism by which the contaminants are separated from the cleaning surface 100b is not necessarily clear. However, since the freezing film 101a has taken in contaminants, it is considered that when cracks occur (when the freezing film 101a is deformed convexly outward), the contaminants are separated from the cleaning surface 100b.

[0094] However, when cracks occur, an impact force is generated. When an impact force is generated, the uneven portions formed on the cleaning surface 100b of the substrate 100 may collapse. Therefore, depending on the state of the cleaning surface 100b, it may be preferable to generate cracks in some cases, and it may be preferable not to generate cracks in other cases.

[0095] For example, the detection unit 8 obtains in advance the temperature at which cracks occur or the time from the start of freezing of the liquid film until cracks occur. Then, according to the state of the cleaning surface 100b of the substrate 100, the temperature at which the freezing film 101a is thawed or the time from the start of freezing of the liquid film until thawing is selected. When freeze-cleaning a substrate 100 for which the occurrence of cracks is not preferable, if the detection unit 8 detects the occurrence of cracks, it is possible to warn of the collapse of the uneven portions.

[0096] Next, as shown in FIGS. 2 and 3, after the freezing process (solid phase), a thawing process and a back surface cleaning process are executed. The thawing process and the back surface cleaning process may be executed simultaneously, for example. In the thawing process, the controller 10 controls the supply unit 4b and the flow rate control unit 4c to supply a liquid 101 at a predetermined flow rate to the cleaning surface 100b of the substrate 100. In the back surface cleaning process, the controller 10 controls the supply unit 5b and the flow rate control unit 5c to supply a liquid 102 at a predetermined flow rate to the back surface 100a of the substrate 100. That is, the controller 10 controls the supply of the liquid 101 to supply the liquid 101 to the frozen liquid film (frozen film 101a) on the cleaning surface 100b of the substrate 100. When the controller 10 supplies the liquid 101 to the frozen liquid film, it controls the supply of the liquid 102 to supply the liquid 102 to the back surface 100a of the substrate 100.

[0097] Further, the controller 10 controls the flow rate control unit 3c to stop the supply of the cooling gas 3a1. Further, the controller 10 controls the drive unit 2c to increase the rotation speed of the substrate 100 to a fourth rotation speed. The fourth rotation speed can be, for example, about 200 rpm to 700 rpm.

[0098] If the rotation of the substrate 100 becomes faster, the liquid 101 and the frozen liquid 101 can be shaken off by centrifugal force. Therefore, the liquid 101 and the frozen liquid 101 can be discharged from the cleaning surface 100b of the substrate 100. At this time, the contaminants separated from the cleaning surface 100b of the substrate 100 are also discharged together with the liquid 101 and the frozen liquid 101. Also, if the rotation of the substrate 100 becomes faster, the liquid 102 can be shaken off by centrifugal force. Therefore, the liquid 102 can be discharged from the back surface 100a of the substrate 100. At this time, the contaminants adhering to the back surface 100a of the substrate 100 are also discharged together with the liquid 102.

[0099] Note that the supply amount of the liquid 101 is not particularly limited as long as thawing is possible. Also, the supply amount of the liquid 102 is not particularly limited as long as the back surface 100a of the substrate 100 can be cleaned. Also, the fourth rotation speed of the substrate 100 is not particularly limited as long as the liquid 101, the frozen liquid 101, and the contaminants can be discharged from the cleaning surface 100b of the substrate 100, and the liquid 102 and the contaminants can be discharged from the back surface 100a of the substrate 100.

[0100] Next, as shown in FIGS. 2 and 3, a drying process is performed. In the drying process, the controller 10 controls the supply unit 4b and the flow rate control unit 4c to stop the supply of the liquid 101. Further, the controller 10 controls the supply unit 5b and the flow rate control unit 5c to stop the supply of the liquid 102.

[0101] Also, the controller 10 controls the drive unit 2c to increase the rotation speed of the substrate 100 to a fifth rotation speed faster than the fourth rotation speed. If the rotation of the substrate 100 becomes faster, the drying of the substrate 100 can be performed quickly. Note that the fifth rotation speed of the substrate 100 is not particularly limited as long as drying is possible.

[0102] The substrate 100 for which the freeze cleaning process has ended is carried out of the housing 6 through a carry-in / carry-out port (not shown) of the housing 6. By doing the above, one freeze cleaning process can be performed.

[0103] Note that the freeze cleaning process can also be performed a plurality of times. When the freeze cleaning process is performed a plurality of times, the drying process in the currently executed freeze cleaning process (the freeze cleaning process) can be omitted. For example, when the freeze cleaning process is repeatedly performed a plurality of times, one freeze cleaning process may include at least a supercooling process, a freezing process (solid-liquid phase), a freezing process (solid phase), a thawing process, and a back surface cleaning process.

[0104] As described above, according to the present embodiment, the freeze cleaning treatment process (pre-cooling process, liquid film formation process, freezing process, thawing process, drying process) is performed with the cleaning surface 100b of the substrate 100 facing downward in the gravity direction. As a result, the force in the direction away from the cleaning surface 100b (substrate 100) due to gravity acts on the contaminants attached to the cleaning surface 100b of the substrate 100. Therefore, in addition to the pressure wave and physical force generated when the liquid film freezes, the contaminants can be removed with the assistance of gravity. Thereby, the removal rate of the contaminants can be improved. In addition, by performing the cleaning with the cleaning surface 100b of the substrate 100 facing downward in the gravitational direction, the back surface 100a of the substrate 100 faces upward in the gravitational direction. Therefore, it becomes possible to clean the back surface 100a, which could not be performed when the back surface 100a faced downward in the gravitational direction. As a result, during the thawing process of the frozen film 101a on the cleaning surface 100b, by cleaning the back surface 100a of the substrate 100 in parallel, it is possible to suppress the reattachment of particles to the substrate 100 during the thawing process.

[0105] As described above, the embodiments have been illustrated. However, the present invention is not limited to these descriptions. Regarding the above-described embodiments, those in which a person skilled in the art appropriately adds, deletes, or changes the design of components, or adds, omits, or changes conditions of processes, are also included in the scope of the present invention as long as they have the features of the present invention.

[0106] For example, the shape, dimensions, number, arrangement, etc. of each element included in the substrate processing apparatus 1 are not limited to those illustrated and can be appropriately changed.

Explanation of Reference Numerals

[0107] 1 Substrate processing apparatus, 2 Mounting portion, 3 Cooling portion, 3a1 Cooling gas, 4 First liquid supply portion, 5 Second liquid supply portion, 6 Housing, 10 Controller, 100 Substrate, 100a Back surface, 100b Cleaning surface, 101 Liquid, 101a Frozen film, 102 Liquid

Claims

1. A substrate processing apparatus comprising: a mounting table that supports the substrate with the cleaning surface of the substrate facing downward in the direction of gravity and is rotatable; a cooling unit capable of supplying a cooling gas from above in the direction of gravity to the surface of the substrate opposite to the cleaning surface; a first liquid supply unit capable of supplying a first liquid from below in the direction of gravity to the cleaning surface of the substrate; a second liquid supply unit capable of supplying a second liquid from above in the direction of gravity to the surface of the substrate opposite to the cleaning surface; a controller capable of controlling the rotation of the substrate, the supply of the cooling gas, the supply of the first liquid, and the supply of the second liquid; wherein the controller controls the supply of the first liquid to continuously supply the first liquid to the cleaning surface of the substrate in a preliminary process of equalizing the in-plane temperature of the substrate; stop the supply of the first liquid in a liquid film forming process of forming a liquid film of the first liquid having a predetermined thickness on the cleaning surface of the substrate after the preliminary process; continue to stop the supply of the first liquid in a supercooling process of supercooling the liquid film of the first liquid on the cleaning surface of the substrate; continuously supply the first liquid to the cleaning surface of the substrate and continuously supply the second liquid to the surface of the substrate opposite to the cleaning surface in a thawing process of thawing the frozen liquid film of the first liquid after the supercooling process.

2. The substrate processing apparatus according to claim 1, wherein the controller controls at least one of the rotation speed of the substrate and the supply amount of the first liquid in the liquid film forming process to make the thickness of the film of the first liquid on the cleaning surface of the substrate 20 μm or more and 500 μm or less.

3. The substrate processing apparatus according to claim 2, wherein the rotation speed of the substrate is 100 rpm or more and 300 rpm or less.

4. The substrate processing apparatus according to claim 2 or 3, wherein the controller controls at least one of the rotation speed of the substrate, the flow rate of the cooling gas, and the supply amount of the first liquid in the supercooling process to make the first liquid on the cleaning surface of the substrate in a supercooled state.

5. The substrate processing apparatus according to any one of claims 1 to 4, wherein the first liquid supply unit has a single-fluid nozzle provided below the substrate in the direction of gravity. ​

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