JP2022143646A - Substrate processing apparatus - Google Patents

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

An embodiment of the present invention relates to a substrate processing apparatus.

A freeze cleaning method has been proposed as a method for removing contaminants such as particles adhering to the surfaces of substrates such as imprint templates, photolithography masks, and semiconductor wafers.

In a general freeze cleaning method, first, a substrate is mounted on a mounting table. At this time, the surface of the substrate on which the freeze cleaning is to be performed (for example, the surface on which the pattern of unevenness is formed) faces upward in the direction of gravity. Next, for example, when pure water is used as the liquid used for cleaning, pure water and cooling gas are supplied to the surface of the rotated substrate on the freeze cleaning side (hereinafter simply referred to as the cleaning surface). Next, the supply of pure water is stopped, and 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 captured by the ice film and separated from the substrate to be cleaned. Next, pure water is supplied to the ice film to melt the ice film, and contaminants are removed from the cleaning surface of the substrate together with the pure water. (See Patent Document 1, for example)
Freeze cleaning can efficiently remove contaminants from the cleaned surface of the substrate.
However, in recent years, it has been desired to further improve the removal rate of contaminants.

JP 2008-71875 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate processing apparatus capable of improving the removal rate of contaminants.

The substrate processing apparatus according to the embodiment supports the substrate with the surface to be cleaned facing downward in the direction of gravity, and includes a mounting table capable of rotating the supported substrate, and a mounting table on a surface opposite to the surface to be cleaned of the substrate. a cooling unit capable of supplying a cooling gas from above in the direction of gravity; a first liquid supply unit capable of supplying a first liquid to the cleaning surface of the substrate from below in the direction of gravity; and a cleaning surface of the substrate. A second liquid supply unit capable of supplying a second liquid from above in the gravitational direction to the opposite surface, rotating the substrate, supplying the cooling gas, supplying the first liquid, and a controller capable of controlling the supply of the liquid.

Embodiments of the present invention provide a substrate processing apparatus capable of improving the removal rate of contaminants.

1 is a schematic diagram for illustrating a substrate processing apparatus according to an embodiment; FIG. 4 is a timing chart for illustrating the action of the substrate processing apparatus; 4 is a graph for illustrating temperature changes of liquid supplied to a substrate;

Hereinafter, embodiments will be illustrated with reference to the drawings. In addition, in each drawing, the same reference numerals are given to the same constituent elements, and detailed description thereof will be 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.

The surface to be cleaned of the substrate 100 may have an uneven portion as a pattern, or may not have an uneven portion. The substrate on which the uneven portion is not formed can be, for example, a substrate before the uneven portion is formed (for example, a so-called bulk substrate).

Moreover, 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 mask for photolithography, the planar shape of the substrate 100 can be substantially rectangular.

FIG. 1 is a schematic diagram for illustrating a substrate processing apparatus 1 according to this embodiment.
As shown in FIG. 1, the substrate processing apparatus 1 includes a mounting portion 2, a cooling portion 3, a first liquid supply portion 4, a second liquid supply portion 5, a housing 6, a blower portion 7, a detection portion 8, an exhaust gas A unit 9 and a controller 10 are provided.

The mounting section 2 has a mounting table 2a, a rotating shaft 2b, and a driving section 2c.
The mounting table 2 a can rotate the substrate 100 . The mounting table 2 a is rotatably provided inside the housing 6 . The mounting table 2a has a plate shape. A plurality of support portions 2a1 for supporting the substrate 100 are provided on one main surface of the mounting table 2a. When the substrate 100 is supported by the plurality of supporting portions 2a1, the cleaning surface 100b of the substrate 100 (the surface on which freeze cleaning is performed) faces the mounting table 2a. For example, when the concave-convex pattern is formed on one surface of the substrate 100, the surface of the substrate 100 on which the concave-convex portion is formed faces the mounting table 2a.
That is, the mounting table 2a supports the substrate 100 with the cleaning surface 100b of the substrate 100 facing downward in the direction of gravity.

Edges of the cleaning surface 100b of the substrate 100 are in contact with the plurality of supporting portions 2a1. A 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 support portion 2a1 that contacts the edge of cleaning surface 100b is tapered, point contact between support portion 2a1 and the edge of cleaning surface 100b can be achieved. If the portion of support portion 2a1 that contacts the edge of cleaning surface 100b is an inclined surface, support portion 2a1 and the edge of cleaning surface 100b can be in line contact. If the support portion 2a1 and the edge of the cleaning surface 100b are brought into point contact or line contact, the substrate 100 can be prevented from being soiled or damaged.

Further, a hole 2aa is provided in the central portion of the mounting table 2a so as to extend through the mounting table 2a in the thickness direction.

One end of the rotary shaft 2b is fitted into the hole 2aa of the mounting table 2a. The other end of the rotating shaft 2b is provided outside the housing 6. As shown in FIG. The rotating shaft 2b is connected to the driving portion 2c outside the housing 6. As shown in FIG.

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

A pipe connecting a flow controller 4c and a liquid nozzle 4d, which will be described later, is attached to the end of the rotating shaft 2b opposite to the mounting table 2a side. 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 portion of the rotating shaft 2b opposite to the mounting table 2a side is sealed so as to be airtight.

The drive unit 2c is provided outside the housing 6. As shown in FIG. The driving portion 2c is connected to the rotating shaft 2b. The drive unit 2c has a rotating device such as a motor. The rotational force of the driving portion 2c is transmitted to the mounting table 2a via the rotating shaft 2b. Therefore, the driving unit 2c can rotate the mounting table 2a and the substrate 100 mounted on the mounting table 2a.

Further, the drive unit 2c can change not only the start and stop of rotation, but also the number of rotations (rotational speed). In this case, the drive unit 2c can be provided with a control motor such as a servomotor, for example.

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

The coolant unit 3a stores the coolant and generates the coolant gas 3a1. The cooling liquid is obtained by liquefying the cooling gas 3a1. The cooling gas 3 a 1 is not particularly limited as long as it is a gas that does not readily react 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.

In this case, the cooling time of the substrate 100 can be shortened by using a gas with a high specific heat. 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.

The cooling liquid unit 3a has a tank that stores the cooling liquid and a vaporization unit that vaporizes the cooling liquid contained in the tank. The tank is provided with a cooling device for maintaining the temperature of the coolant. The evaporator raises the temperature of the cooling liquid to generate cooling gas 3a1 from the cooling liquid. For example, the vaporization section can use the temperature of the outside air or heat with 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 may be -170° C., for example.

The filter 3b is connected to the cooling liquid section 3a via a pipe. The filter 3b prevents contaminants such as particles contained in the coolant from flowing out to the substrate 100 side.

The flow controller 3c is connected to the filter 3b via piping. The flow controller 3c controls the flow rate of the cooling gas 3a1. The flow controller 3c can be, for example, an MFC (Mass Flow Controller). Further, the flow control unit 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 control unit 3c can be, for example, an APC (Auto Pressure Controller).

The temperature of the cooling gas 3a1 generated from the cooling liquid in the cooling liquid section 3a is approximately a predetermined temperature. Therefore, the temperature of the substrate 100 and the temperature of the liquid 101 on the cleaning surface 100b of the substrate 100 can be controlled by controlling the flow rate of the cooling gas 3a1 by the flow control unit 3c. For example, by controlling the flow rate of the cooling gas 3a1 with the flow control unit 3c, the supercooled state of the liquid 101 can be generated in the supercooling step described later.

The cooling nozzle 3d is provided on the upper side of 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 controller 3c via a pipe. A pipe connecting the cooling nozzle 3d and the flow controller 3c is connected to a horizontally extending arm (not shown) that supports the cooling nozzle 3d. An arm (not shown) rotates with the end opposite to the cooling nozzle 3d as a fulcrum. Therefore, the cooling nozzle 3d reciprocates (swings) along an arc-shaped trajectory 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 3 d moves to the center of the mounting table 2 a along the arc-shaped trajectory, the discharge port faces the back surface 100 a of the substrate 100 .

The cooling nozzle 3d supplies the substrate 100 with the cooling gas 3a1 whose flow rate is controlled by the flow control unit 3c. The cooling gas 3a1 emitted from the outlet of the cooling nozzle 3d is directly supplied to the back surface 100a of the substrate 100. As shown in FIG.

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 step (solid-liquid phase), which will be described later, when the liquid 101 changes to a solid, the volume changes and pressure waves are generated. It is believed that this pressure wave separates contaminants adhering to the cleaning surface 100b of the substrate 100 . Therefore, the liquid 101 is not particularly limited as long as it hardly reacts with the material of the substrate 100 .

However, if the liquid 101 is a liquid whose volume increases when frozen, it is conceivable that contaminants adhering to the cleaning surface of the substrate 100 can be separated using the physical force associated with the volume increase. Therefore, the liquid 101 is preferably a liquid that does not easily react with the material of the substrate 100 and that increases in volume when frozen. For example, the liquid 101 can be water (eg, pure water, ultrapure water, etc.), or a liquid containing water as its main component.

The liquid containing water as a main component can be, for example, a mixture of water and alcohol, a mixture of water and an acid solution, a mixture of water and an alkali solution, or the like.
Since the surface tension can be lowered by using a mixture of water and alcohol, it becomes easier to supply the liquid 101 to the inside of the fine irregularities formed on the cleaning surface 100b of the substrate 100 .

A mixed solution of water and an acid solution can dissolve contaminants such as particles and resist residues adhering to the cleaning surface 100b of the substrate 100 . For example, a mixture of water and sulfuric acid can dissolve contaminants such as resist and metal.
Since the mixed liquid of water and alkaline solution can lower the zeta potential, the contaminants separated from the cleaning surface 100b of the substrate 100 can be prevented from reattaching to the cleaning surface 100b of the substrate 100. can be done.

However, if there are too many components other than water, it becomes difficult to utilize the physical force that accompanies the increase in volume, so there is a risk that the contaminant removal rate will decrease. Therefore, the concentration of components other than water is preferably 5 wt % or more and 30 wt % or less.

Further, gas can be dissolved in the liquid 101 . The gas can be, for example, carbon dioxide gas, ozone gas, hydrogen gas, or the like. Dissolving carbon dioxide gas in the liquid 101 can increase the electrical conductivity of the liquid 101, so that the substrate 100 can be neutralized and prevented from being charged. By dissolving ozone gas in the liquid 101, contaminants made of organic substances can be dissolved.

The first liquid supply section 4 has, for example, a liquid storage section 4a, a supply section 4b, a flow control section 4c, and a liquid nozzle 4d. The liquid storage section 4a, the supply section 4b, and the flow control section 4c are provided outside the housing 6. As shown in FIG.

The liquid storage portion 4a stores the liquid 101 described above. The liquid 101 is stored in the liquid storage portion 4a at a temperature higher than its freezing point. The liquid 101 is stored at room temperature (20° C.), for example.

The supply portion 4b is connected to the liquid storage portion 4a via a pipe. The supply unit 4b supplies the liquid 101 stored in the liquid storage unit 4a toward the liquid nozzle 4d. The supply unit 4b can be, for example, a pump that is resistant to the liquid 101, or the like. In addition, although the case where the supply part 4b was a pump was illustrated, the supply part 4b is not necessarily limited to a pump. For example, the supply unit 4b may supply gas to the inside of the liquid storage unit 4a to pump the liquid 101 stored in the liquid storage unit 4a.

The flow control unit 4c is connected to the supply unit 4b via piping. The flow control section 4c controls the flow rate of the liquid 101 supplied by the supply section 4b. The flow controller 4c can be, for example, a flow control valve. The flow control unit 4 c can also start and stop the supply of the liquid 101 .

The liquid nozzle 4 d is provided inside the housing 6 . The liquid nozzle 4d is provided on the lower side of the substrate 100 in the direction of gravity. One end of the liquid nozzle 4d is connected to the flow controller 4c via a pipe. The other end of the liquid nozzle 4d (ejection port for the liquid 101) faces the cleaning surface 100b of the substrate 100 mounted on the mounting table 2a. The other end of the liquid nozzle 4 d is positioned substantially in the center of the cleaning surface 100 b of the substrate 100 .

A liquid 101 ejected from the liquid nozzle 4 d is supplied to the cleaning surface 100 b of the substrate 100 . At this time, the liquid nozzle 4d is attached to the mounting table of the rotating shaft 2b via, for example, a rotating shaft seal (not shown) so that the liquid 101 dropped from the cleaning surface 100b of the substrate 100 does not enter the inside of the rotating shaft 2b. It is sealed with the end on the side of 2a. 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 connected to the rotating shaft 2b so that the liquid 101 does not enter the inside of the rotating shaft 2b. It is preferably larger than the end on the mounting table 2a side. It is preferable that the liquid 101 ejected 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 over a wide area (the entire cleaning surface of the substrate). That is, the first liquid supply unit 4 can have a one-fluid nozzle provided on the lower side of the substrate 100 in the gravitational direction.

The liquid 101 ejected from the liquid nozzle 4 d adheres to the cleaning surface 100 b 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 liquid 101 having a substantially constant thickness is formed on cleaning surface 100b of substrate 100 . Note that the film of the liquid 101 formed on the cleaning surface 100b of the substrate 100 is hereinafter referred to as a liquid film.

The second liquid supply unit 5 supplies the liquid 102 (corresponding to an example of the second liquid) to the rear surface 100a of the substrate 100 from the upper side in the direction of gravity. The second liquid supply section 5 has, for example, a liquid storage section 5a, a supply section 5b, a flow control section 5c, and a liquid nozzle 5d. The liquid storage section 5a, the supply section 5b, and the flow rate control section 5c are provided outside the housing 6. As shown in FIG.

The liquid 102 is used in the back surface cleaning process, which will be described later. Therefore, the liquid 102 is not particularly limited as long as it hardly reacts with the material of the substrate 100 and does not easily remain on the rear surface 100a of the substrate 100 in the drying process described below. The liquid 102 can be, for example, water (eg, pure water, ultrapure water, etc.), a mixture of water and alcohol, or the like.
The temperature of liquid 102 is not particularly limited. The temperature of the liquid 102 can be, for example, normal temperature (20° C.).

The liquid storage portion 5a can be the same as the liquid storage portion 4a described above. The supply unit 5b can be similar to the supply unit 4b described above. The flow control unit 5c can be the same as the flow control unit 4c described above.

When the liquid 102 and the liquid 101 are the same, the first liquid supply section 4 and the second liquid supply section 5 may share the liquid storage section 4a and the supply section 4b.

The liquid nozzle 5 d is provided inside the housing 6 . The liquid nozzle 5d is provided on the upper side of 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 controller 5c via a pipe. The other end of the liquid nozzle 5d faces the rear surface 100a of the substrate 100 mounted on the mounting table 2a. The other end of the liquid nozzle 5 d is an outlet for the liquid 102 . Therefore, the liquid 102 ejected from the liquid nozzle 5 d is supplied to the back surface 100 a of the substrate 100 .

Further, the piping that connects the liquid nozzle 5d and the flow controller 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. An arm (not shown) rotates with the end opposite to the liquid nozzle 5d as a fulcrum. Therefore, the liquid nozzle 5d reciprocates (swings) along an arc-shaped trajectory between the central portion and the outer peripheral side of the mounting table 2a. The other end of the liquid nozzle 5d is positioned substantially at the center of the rear surface 100a of the substrate 100 when the liquid nozzle 5d moves along the arc-shaped trajectory to the center of the mounting table 2a. The liquid 102 ejected from the liquid nozzle 5 d spreads from substantially the center of the back surface 100 a of the substrate 100 and is discharged from the periphery of the back surface 100 a of the substrate 100 .

The housing 6 has a box shape. A cover 6 a is provided inside the housing 6 . The cover 6a receives the liquids 101 and 102 supplied to the substrate 100 and discharged to the outside of the substrate 100 as the substrate 100 rotates. The cover 6a has a tubular shape. The vicinity of the end of the cover 6a opposite to the mounting table 2a side (the vicinity of the upper end of the cover 6a) is bent toward the center of the cover 6a. Therefore, the liquids 101 and 102 splashing above the substrate 100 can be easily captured.

A partition plate 6 b is provided inside the housing 6 . The partition plate 6 b is provided between the outer surface of the cover 6 a and the inner surface of the housing 6 .

A plurality of outlets 6c are provided on the side surface of the housing 6 on the bottom side. 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 to the outside of the housing 6 from the discharge port 6c.

The outlet 6 c is provided below the substrate 100 . Therefore, the cooling gas 3a1 is discharged from the discharge port 6c to create a downflow flow. As a result, it is possible to prevent the particles from soaring.

In a plan view, the plurality of discharge ports 6c are provided symmetrically with respect to the center of the housing 6. As shown in FIG. By doing so, the exhaust direction of the cooling gas 3a1 becomes symmetrical with respect to the center of the housing 6. FIG. If the cooling gas 3a1 is discharged symmetrically, the cooling gas 3a1 can be discharged smoothly.

The air blower 7 is provided on the ceiling surface of the housing 6 . Note that the air blower 7 can also be provided on the side surface of the housing 6 as long as it is on the ceiling side. The blower section 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).

The air blower 7 supplies air 7 a (outside air) to the space between the partition plate 6 b 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 air blower 7 to the discharge port 6c. In addition, it is possible to prevent contaminants such as particles from entering the housing 6 through the outlet 6c.

In addition, the air blower 7 can also supply dry room temperature air 7 a to the substrate 100 . Therefore, the air blower 7 can also accelerate the drying of the liquids 101 and 102 in the drying process described below.

The detector 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 liquid 101 and the frozen liquid 101 are mixed, and the temperature of the frozen liquid 101 (frozen film). In this case, the detector 8 can be, for example, a radiation thermometer, a thermoviewer, a thermocouple, or a resistance temperature detector. Further, the detection unit 8 may detect the thickness of the film and the surface position of the film. In this case, the detector 8 can be, for example, a laser displacement gauge, an ultrasonic displacement gauge, or the like. Further, the detection unit 8 may be an optical sensor, an image sensor, or the like that detects the surface state of the film.

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. Controlling the supercooled state means controlling the temperature change curve of the liquid 101 in the supercooled state to prevent the liquid 101 from freezing due to rapid cooling. to ensure that it is maintained.

For example, the detected temperature, thickness, and surface state of the frozen film are used to detect the occurrence of cracks in the frozen film (hereinafter referred to as "occurrence of cracks") in the freezing step (solid phase) described later. can be used for
For example, when the detection unit 8 detects temperature, it is possible to indirectly detect "occurrence of cracks" from the temperature of the frozen film in the freezing step (solid phase), which will be described later. When the detector 8 detects the thickness, it is possible to detect "occurrence of cracks" from changes in the surface position of the frozen film in the freezing step (solid phase) described later. When the detection unit 8 detects the surface state, it is possible to detect "occurrence of cracks" from the surface state of the frozen film in the freezing step (solid phase) described later.
Details of cracks will be described later.

The exhaust part 9 is connected to the exhaust port 6c via an exhaust pipe 6c1. The exhaust unit 9 exhausts the used cooling gas 3 a 1 and the air 7 a to the outside of the housing 6 . The exhaust unit 9 can be, for example, a pump or a blower. The used liquids 101 and 102 are discharged to the outside of the housing 6 via a discharge pipe 6c2 connected to the exhaust pipe 6c1.

The controller 10 controls the operation of each element 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 .
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. Controller 10 is, for example, a computer. The storage unit can store a control program for controlling the operation of each element provided in the substrate processing apparatus 1 . The calculation unit controls the operation of each element 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.

For example, the cooling rate of the liquid 101 has a correlation with the thickness of the liquid film. For example, the thinner the liquid film is, the faster the liquid 101 is cooled. Conversely, as the thickness of the liquid film increases, the cooling rate of the liquid 101 decreases. 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 (thickness of the liquid film) detected by the detection unit 8, for example. The temperature and cooling rate of the liquid 101 are controlled, for example, when controlling the supercooled state of the liquid 101 in the supercooling step described later.

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 supercooled. so that

Next, the operation of the substrate processing apparatus 1 will be illustrated.
FIG. 2 is a timing chart for illustrating the action of the substrate processing apparatus 1. FIG.
FIG. 3 is a graph for illustrating temperature changes of the liquid 101 supplied to the substrate 100. FIG.
2 and 3, 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.

First, the substrate 100 is loaded into the housing 6 through a loading/unloading port (not shown) of the housing 6 . The loaded substrate 100 is placed and supported on the plurality of supporting portions 2a1 of the placing table 2a.
At this time, the cleaning surface 100b of the substrate 100 is made to face the mounting table 2a side (lower side in the direction of gravity). For example, the substrate 100 is transported by a transport robot (not shown) having a mechanism for reversing the orientation of the substrate 100 . Alternatively, a reversing unit having a mechanism for reversing the orientation of the substrate 100 is provided outside the housing 6 .

After the substrate 100 is supported on the mounting table 2a, as shown in FIG. 2, 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.

First, preliminary steps are performed as shown in FIGS. In the preliminary process, the controller 10 controls the supply section 4b and the flow rate control section 4c to supply the liquid 101 at a predetermined flow rate to the cleaning surface 100b of the substrate 100 . Further, the controller 10 controls the flow control unit 3c to supply the cooling gas 3a1 at a predetermined flow rate to the back surface 100a of the substrate 100. FIG. Further, the controller 10 controls the drive section 2c to rotate the substrate 100 at the third rotation speed.

Here, if 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 and cause contamination. Since the liquid 101 is continuously supplied to the cleaning surface 100b of the substrate 100 in the preparatory step, the substrate 100 can be uniformly cooled and frost can be prevented from adhering to the cleaning surface 100b of the substrate 100. FIG. In addition, since the cleaning surface 100b of the substrate 100 faces downward in the direction of gravity, it is possible to more reliably prevent frost from adhering to the cleaning surface 100b of the substrate 100. FIG.

In the case illustrated in FIG. 2, the third rotation speed of the substrate 100 is, for example, approximately 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. Also, the flow rate of the cooling gas 3a1 is, for example, about 40 NL/min to 200 NL/min. Moreover, the process time of the preliminary process is, for example, about 1800 seconds. It should be noted that the process time of the preparatory process may be any time during which the in-plane temperature of the substrate 100 becomes substantially uniform, and can be obtained by performing experiments or simulations in advance.

The temperature of the liquid film in the preliminary step is almost the same as the temperature of the supplied liquid 101 because the liquid 101 is in a flowing state. For example, if the temperature of the supplied liquid 101 is about normal temperature (20° C.), the temperature of the liquid film is about normal temperature (20° C.).

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

Here, if the thickness of the liquid film is made too thin, it becomes difficult to remove contaminants. Further, since the cleaning surface 100b of the substrate 100 faces downward in the direction of gravity, if the thickness of the liquid film is excessively increased, the in-plane distribution of the thickness of the liquid film becomes large. As the in-plane distribution of the thickness of the liquid film increases, the in-plane distribution of the contaminant removal rate also increases.

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 thickness of the liquid film can be reduced, and the in-plane distribution of the contaminant removal rate can be reduced. .
For example, the controller 10 controls at least one of the number of rotations of the substrate 100 and the amount of supply of the liquid 101 to increase the thickness of the liquid film (film of the liquid 101) on the cleaning surface 100b of the substrate 100 to 20 μm or more. 500 μm or less. In this case, if the second rotational speed is set to 100 rpm or more and 300 rpm or less, the thickness of the liquid film can be easily made 20 μm or more and 500 μm or less. That is, the controller 10 rotates the substrate 100 at the same number of rotations as in the preliminary process or at a number of rotations smaller than that in the preliminary process.

In the liquid film forming process, for example, as shown in FIG. 2, the supply of the liquid 101 that has been supplied in the preliminary process is stopped, and the substrate 100 is rotated at the second rotation speed until the substrate 100 reaches a predetermined thickness. It may be confirmed by measuring the thickness of the liquid film with the detection unit 8 whether or not the predetermined thickness has been reached. The thickness of the liquid film may be measured by the detection unit 8, and the second number of rotations may be maintained for a pre-calculated time for the liquid film to reach a predetermined thickness from the measured thickness.

After that, the rotation speed of the substrate 100 is set to the first rotation speed. The first number of rotations is a number of rotations at which the liquid film formed on the cleaning surface 100b of the substrate 100 is maintained to have a uniform thickness. The first rotation speed may be any rotation speed that can suppress variations in the thickness of the liquid film due to centrifugal force, and may be, for example, about 0 rpm to 50 rpm.

The flow rate of the cooling gas 3a1 in the liquid film forming process is the same as the flow rate of the cooling gas 3a1 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 same flow rate of the cooling gas 3a1 as in the preliminary process in the liquid film forming process, the in-plane temperature of the substrate 100 can be kept substantially uniform.

Further, when it is desired to increase the thickness of the liquid film, the number of rotations can be changed from the third number of rotations to the first number of rotations instead of the second number of rotations. In this case, it is preferable that the first rotation speed be a rotation speed close to 0 rpm.
The number of revolutions in the preliminary process and the process of forming the liquid film may be the first number of revolutions. Also, the third rotation speed may be a rotation speed slower than the first rotation speed.

Further, when shifting from the preliminary process to the liquid film forming process, the liquid 101 supplied in the preliminary process may be discharged by rotating the substrate 100 at high speed. In this case, after the liquid 101 is discharged, the rotation speed of the substrate 100 is set to the second rotation speed, and a predetermined amount of the liquid 101 is supplied to the cleaning surface 100b of the substrate 100 . By doing so, a liquid film having a predetermined thickness can be easily formed.

A cooling step is then performed as shown in FIGS. In the present embodiment, in the cooling process, the period before the supercooled liquid 101 starts to freeze is referred to as the "supercooling process", and the supercooled liquid 101 starts to freeze and freezes. The period before complete completion is called the “freezing step (solid-liquid phase)”, and the step of further cooling the frozen liquid 101 is called the “freezing step (solid phase)”.

For example, in the supercooling process, only the liquid 101 exists on the cleaning surface 100b of the substrate 100. FIG. For example, in the freezing process (solid-liquid phase), the liquid 101 and the frozen liquid 101 exist on the cleaning surface 100b of the substrate 100 . For example, in the freezing step (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 the liquid 101 and the frozen liquid 101 exist entirely. A state in which only the frozen liquid 101 is present is called a frozen film 101a.

First, in the supercooling process, the cooling gas 3a1 continuously supplied to the back surface 100a of the substrate 100 makes the temperature of the liquid film formed on the cleaning surface 100b higher than the temperature of the liquid film in the liquid film forming process. fall and become supercooled.

Here, if the cooling rate of the liquid 101 is too high, the liquid 101 will not be in a supercooled state and will freeze immediately. Therefore, the controller 10 controls at least one of the number of rotations of the substrate 100, the flow rate of the cooling gas 3a1, and the amount of supply of the liquid 101 so that the liquid 101 on the cleaning surface 100b of the substrate 100 is supercooled. be.

The control conditions for the supercooled state of the liquid 101 are affected by the size of the substrate 100, the viscosity of the liquid 101, the specific heat of the cooling gas 3a1, and the like. Therefore, it is preferable to appropriately determine the control conditions under which the liquid 101 is in the supercooled state through experiments and simulations.

In the supercooled state, freezing of the liquid 101 starts due to, for example, the temperature of the liquid film, the presence of contaminants such as particles and air bubbles, vibration, and the like. For example, when contaminants such as particles are present, the liquid 101 starts to freeze when the temperature T of the liquid 101 becomes -35°C or higher and -20°C or lower. Further, by vibrating the liquid 101 by, for example, changing the rotation speed of the substrate 100, freezing of the liquid 101 can be started.

When the supercooled liquid 101 starts to freeze, the supercooling process shifts to the freezing process (solid-liquid phase). In the liquid 101 in the supercooled state, some percentage of starting points of freezing become contaminants. The cleaning surface 100b of the substrate 100 is affected by the fact that the contaminant becomes the starting point of freezing, the pressure wave is generated due to the change in volume when the liquid 101 changes to solid, and the physical force is generated due to the increase in volume. Adhering contaminants are believed to be separated.

In addition, as described above, since the cleaning surface 100b of the substrate 100 faces downward in the direction of gravity, the contaminants adhering to the cleaning surface 100b are easily separated by gravity.

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

In the freezing step (solid-liquid phase), the liquid film does not freeze instantly. In the freezing step (solid-liquid phase), the liquid 101 and the frozen liquid 101 are present all over the cleaning surface 100b of the substrate 100 .

Latent heat is generated when the liquid 101 freezes. The release of latent heat raises the temperature of the frozen liquid 101 to its freezing point.

The cooling gas 3a1 is supplied to the back surface 100a of the substrate 100 also in the freezing step (solid-liquid phase). Therefore, the rate of latent heat generation and the rate of cooling 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, no latent heat is generated. On the other hand, the supply of cooling gas 3a1 to back surface 100a of substrate 100 is maintained. Therefore, once the frozen film 101a is formed, the temperature of the frozen film 101a begins to drop.

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

Here, the liquid 101 mainly contains water. Therefore, the liquid film on the cleaning surface 100b of the substrate 100 is completely frozen to form a frozen film 101a. When the temperature of the frozen film 101a further decreases, the volume of the frozen film 101a is reduced and stress is applied to the frozen film 101a. Occur. In this case, when the temperature of the frozen film drops below −50° C., cracks occur in the frozen film 101a because the increased stress cannot be endured.

When the frozen film 101a cracks, contaminants attached to the cleaning surface 100b of the substrate 100 are separated from the cleaning surface 100b. The mechanism by which contaminants are separated from the cleaning surface 100b is not necessarily clear. However, since contaminants are trapped in the frozen film 101a, when a crack occurs (when the frozen film 101a deforms convexly toward the outside), the contaminants are separated from the cleaning surface 100b. Conceivable.

However, when cracks occur, an impact force is generated. When the impact force is generated, the irregularities 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, or it may be preferable not to generate cracks.

For example, the temperature at which cracking occurs or the time from the start of freezing of the liquid film until the cracking occurs is determined in advance by the detector 8 . Then, depending on the state of the cleaning surface 100b of the substrate 100, the temperature for thawing the frozen film 101a or the time from the start of freezing of the liquid film to thawing is selected. When the substrate 100 on which cracking is undesirable is subjected to freeze cleaning, if the detection unit 8 detects cracking, it is possible to issue a warning that the uneven portion will collapse.

Next, as shown in FIGS. 2 and 3, a freezing step (solid phase) is followed by a thawing step and a back surface cleaning step. The thawing step and the backside cleaning step, for example, may be performed simultaneously.
In the thawing process, the controller 10 controls the supply unit 4b and the flow rate control unit 4c to supply the liquid 101 at a predetermined flow rate to the cleaning surface 100b of the substrate 100. FIG.
In the back surface cleaning process, the controller 10 controls the supply unit 5b and the flow control unit 5c to supply the liquid 102 at a predetermined flow rate to the back surface 100a of the substrate 100. FIG.
That is, the controller 10 controls the supply of the liquid 101 to supply the liquid 101 to the frozen liquid 101 film (frozen film 101 a ) on the cleaning surface 100 b of the substrate 100 . When supplying the liquid 101 to the frozen film of the liquid 101 , the controller 10 controls the supply of the liquid 102 to supply the liquid 102 to the rear surface 100 a of the substrate 100 .

Further, the controller 10 controls the flow control section 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 the fourth rotation speed. The fourth rotation speed can be, for example, approximately 200 rpm to 700 rpm.

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

The amount of liquid 101 to be supplied is not particularly limited as long as it can be thawed.
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.
Further, the fourth rotation speed of the substrate 100 can discharge the liquid 101, the frozen liquid 101, and the contaminants from the cleaning surface 100b of the substrate 100, and the liquid 102, And there is no particular limitation as long as it can discharge contaminants.

Next, a drying process is performed as shown in FIGS. In the drying process, the controller 10 controls the supply section 4b and the flow control section 4c to stop the supply of the liquid 101. FIG. The controller 10 also controls the supply unit 5b and the flow control unit 5c to stop the supply of the liquid 102. FIG.

Also, the controller 10 controls the drive unit 2c to increase the rotation speed of the substrate 100 to a fifth rotation speed higher than the fourth rotation speed. The faster the substrate 100 rotates, the faster the substrate 100 can be dried. Note that the fifth number of rotations of the substrate 100 is not particularly limited as long as the substrate can be dried.

The substrate 100 for which the freeze cleaning process has been completed is carried out of the housing 6 through a loading/unloading port (not shown) of the housing 6 .
By doing so, one freeze cleaning step can be performed.

In addition, the freeze washing process can also be performed several times. When the freeze cleaning process is performed multiple times, the drying process in the current freeze cleaning process (the freeze cleaning process) can be omitted.
For example, when the freeze cleaning process is repeated multiple times, one freeze cleaning process includes 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. should be

As described above, according to the present embodiment, the freeze cleaning process (pre-cooling process, liquid film forming process, freezing process, thawing process, drying process) is performed with the cleaning surface 100b of the substrate 100 facing downward in the direction of gravity. I made it As a result, a force directed away from the cleaning surface 100 b (substrate 100 ) due to gravity acts on the contaminants attached to the cleaning surface 100 b of the substrate 100 . Therefore, in addition to the pressure waves and physical force generated when the liquid film freezes, the gravitational assistance can remove contaminants. This can improve the removal rate of contaminants.
In addition, since the cleaning is performed with the surface 100b of the substrate 100 facing downward in the direction of gravity, the back surface 100a of the substrate 100 becomes the upper side in the direction of gravity. Therefore, the back surface 100a can be cleaned, which cannot be performed when the back surface 100a faces downward in the direction of gravity. By cleaning the back surface 100a of the substrate 100 in parallel with the step of thawing the frozen film 101a on the cleaning surface 100b, particles can be prevented from reattaching to the substrate 100 during the step of thawing.

The embodiments have been illustrated above. However, the invention is not limited to these descriptions. Regarding the above-described embodiments, those in which those skilled in the art appropriately add, delete, or change the design of components, or add, omit, or change the conditions of steps, as long as they have the features of the present invention. are included within the scope of the present invention.

For example, the shape, size, number, arrangement, etc. of each element provided in the substrate processing apparatus 1 are not limited to those illustrated and can be changed as appropriate.

Reference Signs List 1 substrate processing apparatus 2 placement section 3 cooling section 3a1 cooling gas 4 first liquid supply section 5 second liquid supply section 6 housing 10 controller 100 substrate 100a back surface 100b cleaning surface 101 liquid, 101a frozen film, 102 liquid

Claims (7)

a mounting table that supports the substrate with the surface to be cleaned of the substrate facing downward in the direction of gravity, and that can rotate 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 surface to be cleaned;
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 gravitational direction to the surface of the substrate opposite to the cleaning surface;
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;
A substrate processing apparatus with The controller controls at least one of the number of rotations of the substrate and the amount of supply of the first liquid to increase the thickness of the film of the first liquid on the cleaning surface of the substrate to 20 μm or more and 500 μm. 2. The substrate processing apparatus according to claim 1, wherein: 3. The substrate processing apparatus according to claim 2, wherein the rotation speed of said substrate is 100 rpm or more and 300 rpm or less. The controller controls at least one of the number of rotations of the substrate, the flow rate of the cooling gas, and the amount of supply of the first liquid, so that the first liquid on the cleaning surface of the substrate is in a supercooled state. 4. The substrate processing apparatus according to claim 2 or 3, wherein: The controller is
controlling the supply of the first liquid to supply the first liquid to the frozen first liquid film on the cleaning surface of the substrate;
5. The method according to any one of claims 1 to 4, wherein in parallel with the supply of the first liquid, the supply of the second liquid is controlled to supply the second liquid to the surface of the substrate opposite to the surface to be cleaned. 1. The substrate processing apparatus according to claim 1. 6. The substrate processing apparatus according to any one of claims 1 to 5, wherein the first liquid supply section has a one-fluid nozzle provided below the substrate in the direction of gravity. The controller controls the supply of the first liquid,
continuously supplying the first liquid to the cleaning surface of the substrate in a preliminary step of equalizing the in-plane temperature of the substrate;
In the 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, the supply of the first liquid is stopped;
continuing to stop the supply of the first liquid in the supercooling step of bringing the liquid film of the first liquid on the cleaning surface of the substrate into a supercooled state;
In the thawing step of thawing the frozen liquid film of the first liquid after the supercooling step, the first liquid is continuously supplied to the cleaning surface of the substrate, and the second liquid is supplied. The substrate processing apparatus according to any one of claims 1 to 6, wherein the surface of the substrate opposite to the surface to be cleaned is continuously supplied.

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