JP2015185668A - Substrate processing method and substrate processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate processing method capable of enhancing a particle removal rate in frozen cleaning and to provide a substrate processing apparatus.SOLUTION: A liquid film covering a top face of a substrate W is formed. Then, after freezing a portion other than a peripheral part of the liquid film, a thickness of the peripheral part of the liquid film is reduced so that a difference between a thickness of the peripheral part of the liquid film and a thickness of the liquid film in a center part is reduced. Then, the peripheral part of the liquid film is frozen. Thus, a whole liquid film is frozen and a frozen film covering the top face of the substrate W is formed.

Description

  The present invention relates to a substrate processing method and a substrate processing apparatus for processing a substrate. Examples of substrates to be processed include semiconductor wafers, liquid crystal display substrates, plasma display substrates, FED (Field Emission Display) substrates, optical disk substrates, magnetic disk substrates, magneto-optical disk substrates, and photomasks. Substrate, ceramic substrate, solar cell substrate and the like.

In a manufacturing process of a semiconductor device or a liquid crystal display device, a cleaning process is performed to remove contaminants such as particles from a substrate such as a semiconductor wafer or a glass substrate for a liquid crystal display device.
Patent Document 1 discloses a single-wafer type substrate processing apparatus that performs freeze cleaning. Freezing cleaning is a cleaning method in which a liquid film covering the upper surface of a substrate is frozen and then the thawed liquid film is removed from the substrate. Contaminants such as particles are weakened in adhesion to the substrate by the force generated by freezing of the liquid film.

JP 2012-74554 A

As described in Patent Document 1, in order to ensure a high particle removal rate in freeze cleaning, it is necessary to adjust the thickness of the liquid film within a predetermined range, and the thickness of the liquid film is larger than that range. Even if it is small, the particle removal rate is lowered. Therefore, it is desirable that the thickness of the liquid film is within an optimum range over the entire area.
However, the thickness of the liquid film partially increases at the outer periphery of the upper surface of the substrate due to the centrifugal force due to the rotation of the substrate and the surface tension of the liquid on the substrate. It cannot be adjusted within the optimum range. When the thickness of the portion other than the outer peripheral portion of the liquid film is adjusted within the optimum range, the particle removal rate at the outer peripheral portion of the upper surface of the substrate is deteriorated.

  Accordingly, one of the objects of the present invention is to provide a substrate processing method and a substrate processing apparatus that can increase the particle removal rate in freeze cleaning.

  The invention according to claim 1 for achieving the object includes a liquid film forming step of forming a liquid film covering an upper surface of a substrate, a freezing step of freezing the liquid film after the liquid film forming step, Is a substrate processing method. In the freezing step, after the liquid film forming step, the first freezing step for freezing the portion other than the outer peripheral portion of the liquid film, and after the first freezing step, the thickness of the outer peripheral portion of the liquid film is reduced. The film thickness equalizing step for reducing the difference between the thickness of the outer peripheral portion of the liquid film and the thickness of the central portion of the liquid film, and the outer peripheral portion of the liquid film is frozen after the film thickness equalizing step. And a second freezing step.

  According to this method, a liquid film covering the upper surface of the substrate is formed. And after freezing parts other than the outer peripheral part of a liquid film, the thickness of the outer peripheral part of a liquid film is reduced. Thereafter, the outer periphery of the liquid film is frozen. As a result, the entire liquid film is frozen, and a frozen film (liquid film after freezing) covering the upper surface of the substrate is formed. Since the thickness of the outer peripheral portion of the liquid film is reduced, the difference between the thickness of the outer peripheral portion of the liquid film and the thickness of the central portion of the liquid film is reduced, and the uniformity of the film thickness is increased. For this reason, the thickness of the frozen membrane can be set within the optimum range over the entire area. Thereby, the particle removal rate can be increased.

A second aspect of the present invention is the substrate processing method according to the first aspect, wherein the film thickness uniforming step includes an acceleration step of accelerating the substrate in a direction around a rotation axis passing through a central portion of the substrate.
According to this method, after the portion other than the outer peripheral portion of the liquid film is frozen, the substrate is accelerated in the rotation direction. As a result, the centrifugal force applied to the liquid on the substrate increases, and the liquid is discharged from the substrate. Therefore, the thickness of the outer periphery of the liquid film is reduced. On the other hand, the portions other than the outer peripheral portion of the liquid film are already frozen and are not discharged from the substrate. Thereby, the difference between the thickness of the outer peripheral portion of the liquid film and the thickness of the central portion of the liquid film is reduced, and the uniformity of the film thickness is increased. For this reason, the thickness of the frozen membrane can be set within the optimum range over the entire area.

According to a third aspect of the present invention, there is provided a substrate holding means for holding a substrate, a liquid film forming means for forming a liquid film covering an upper surface of the substrate held by the substrate holding means, and freezing for freezing the liquid film. A substrate processing apparatus comprising: a means; a film thickness uniformizing means for reducing the thickness of the outer peripheral portion of the liquid film; and a control means for controlling the liquid film forming means, the freezing means, and the film thickness uniformizing means. is there.
The control means executes a liquid film forming step for forming a liquid film covering the upper surface of the substrate, and a freezing step for freezing the liquid film after the liquid film forming step. In the freezing step, after the liquid film forming step, the first freezing step for freezing the portion other than the outer peripheral portion of the liquid film, and after the first freezing step, the thickness of the outer peripheral portion of the liquid film is reduced. The film thickness equalizing step for reducing the difference between the thickness of the outer peripheral portion of the liquid film and the thickness of the central portion of the liquid film, and the outer peripheral portion of the liquid film is frozen after the film thickness equalizing step. And a second freezing step. According to this configuration, it is possible to achieve an effect similar to the effect described with respect to the invention of claim 1.

It is the schematic diagram which looked at the inside of the processing unit with which the substrate processing apparatus concerning one embodiment of the present invention was equipped horizontally. It is process drawing which shows an example of the process performed by the process unit. It is a schematic diagram which shows the state of a board | substrate when the process shown in FIG. 2 is performed. 6 is a graph showing a difference in particle removal rate (PRE) of a substrate processed by the method of the prior art and the method of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view of the inside of a processing unit 2 provided in a substrate processing apparatus 1 according to an embodiment of the present invention viewed horizontally.
The substrate processing apparatus 1 is a single-wafer type apparatus that processes a disk-shaped substrate W such as a semiconductor wafer one by one. The substrate processing apparatus 1 includes a processing unit 2 that processes the substrate W, a transfer robot (not shown) that transfers the substrate W to the processing unit 2, and a control device 3 that controls the substrate processing apparatus 1.

  The processing unit 2 is a single-wafer type unit that processes a plurality of substrates W one by one using a processing liquid. The processing unit 2 includes a box-shaped chamber 4 having an internal space, and a substrate W around the vertical rotation axis A1 passing through the central portion of the substrate W while holding a single substrate W in a horizontal posture in the chamber 4. A spin chuck 5 for rotating W. The processing unit 2 further includes a cup 37 surrounding the spin chuck 5 around the rotation axis A1, and a disc-shaped blocking plate 39 disposed above the spin chuck 5 in a horizontal posture.

  The spin chuck 5 includes a disc-shaped spin base 6 held in a horizontal posture, a plurality of chuck pins 7 projecting upward from the outer peripheral portion of the upper surface of the spin base 6, and the spin base 6 and the chuck pins 7 as rotational axes. A spin motor 8 that rotates about A1. The plurality of chuck pins 7 are between a closed position where the plurality of chuck pins 7 hold the substrate W horizontally above the spin base 6 and an open position where the gripping of the substrate W by the plurality of chuck pins 7 is released. , Movable with respect to the spin base 6. Although not shown, the spin chuck 5 includes a chuck opening / closing mechanism that moves a plurality of chuck pins 7 between a closed position and an open position.

  The processing unit 2 includes a lower surface nozzle 9 that discharges the processing liquid toward the center of the lower surface of the substrate W. The processing unit 2 is further provided with a lower room temperature pure water pipe 10 that guides pure water (deionized water: Deionzied Water) at room temperature (for example, 20 to 30 ° C.) to the lower surface nozzle 9 and a lower room temperature pure water pipe 10. The lower room temperature pure water valve 11, the cold water pipe 12 for guiding cold water (pure water having a temperature lower than room temperature) lower than room temperature (for example, pure water lower than room temperature) to the lower surface nozzle 9, and the lower cold water pipe 12 It includes an intervening chilled water valve 13 and a cooler (not shown) that lowers the temperature of pure water supplied from the chilled water pipe 12 to the lower surface nozzle 9 to a temperature lower than room temperature.

  The processing unit 2 further includes a cylindrical lower gas flow path 15 formed by the outer peripheral surface of the lower surface nozzle 9 and the inner peripheral surface of the spin base 6, and a lower gas for introducing nitrogen gas at room temperature to the lower gas flow path 15. A pipe 16, a lower gas valve 17 interposed in the lower gas pipe 16, and a lower gas flow rate adjusting valve 18 that increases or decreases the flow rate of nitrogen gas supplied from the lower gas pipe 16 to the lower gas flow path 15. . The lower gas flow path 15 includes an annular upward discharge port 14 that opens at the center of the upper surface of the spin base 6.

  The processing unit 2 includes a chemical solution nozzle 19 that discharges SC-1 (an aqueous solution containing ammonia and hydrogen peroxide), which is an example of a chemical solution, a nozzle arm 20 having a chemical solution nozzle 19 attached to the tip, and a nozzle. And a chemical nozzle moving unit 21 that moves the chemical nozzle 19 between the processing position and the retracted position by moving the arm 20. The processing unit 2 further includes a chemical liquid pipe 22 that guides the chemical liquid to the chemical liquid nozzle 19 and a chemical liquid valve 23 interposed in the chemical liquid pipe 22. The processing position is a position where the processing liquid discharged from the chemical liquid nozzle 19 is deposited on any position within the upper surface of the substrate W. The retracted position is a position where the chemical nozzle 19 is retracted from above the substrate W. In the following description, the position of the nozzle is represented by a distance R (mm) from the rotation axis A1 of the substrate W held by the spin chuck 5. For example, when the substrate W is a circular semiconductor wafer having a diameter of 300 mm, the processing position is represented by R = 0 to 150.

  The processing unit 2 includes a pure water nozzle 24 for discharging pure water downward, a nozzle arm 25 to which the pure water nozzle 24 is attached at the tip, and a movement of the nozzle arm 25 to thereby change the processing position and the retreat position. And a pure water nozzle moving unit 26 for moving the pure water nozzle 24 therebetween. The processing unit 2 further includes a room temperature pure water pipe 27 that guides room temperature pure water to the pure water nozzle 24, a room temperature pure water valve 28 interposed in the room temperature pure water pipe 27, and a temperature lower than room temperature (for example, 0 .5 ° C.) cold water pipe 29 for introducing cold water to the pure water nozzle 24, a cold water valve 30 interposed in the cold water pipe 29, and the temperature of pure water supplied from the cold water pipe 29 to the pure water nozzle 24 from room temperature. And a cooler (not shown) for lowering the temperature to a lower temperature.

  The processing unit 2 includes a cooling gas nozzle 31 that discharges nitrogen gas having a temperature lower than the freezing point of water at one atmospheric pressure (for example, −100 to −20 ° C., specifically −150 ° C.) downward, and a cooling gas nozzle 31. A nozzle arm 32 attached to the tip portion and a cooling gas nozzle moving unit 33 for moving the cooling gas nozzle 31 between the processing position and the retracted position by moving the nozzle arm 32 are included. The processing unit 2 further includes a cooling gas pipe 34 for introducing a low-temperature nitrogen gas to the cooling gas nozzle 31, a cooling gas valve 35 interposed in the cooling gas pipe 34, and a gas supplied from the cooling gas pipe 34 to the cooling gas nozzle 31. A cooler (not shown) that lowers the temperature of water to a temperature lower than the freezing point of water, and a cooling gas flow rate adjustment valve 36 that increases or decreases the flow rate of nitrogen gas supplied from the cooling gas pipe 34 to the cooling gas nozzle 31. Including.

  The cup 37 can be moved up and down in the vertical direction between an upper position and a lower position. The upper position is a processing position where the upper end of the cup 37 is positioned above the holding position of the substrate W by the spin chuck 5. The lower position is a retracted position (position shown in FIG. 1) in which the upper end of the cup 37 is positioned below the holding position of the substrate W by the spin chuck 5. The processing unit 2 includes a cup elevating unit 38 that elevates and lowers the cup 37 between an upper position and a lower position. In a state where the cup 37 is positioned at the upper position, the processing liquid discharged from the substrate W to the periphery thereof is received by the cup 37 and collected in the cup 37. Then, the processing liquid collected in the cup 37 is recovered or discarded.

  The blocking plate 39 is supported in a horizontal posture by a support shaft 41 extending in the vertical direction along the rotation axis A1. The center line of the blocking plate 39 is disposed on the rotation axis A1. The blocking plate 39 includes a circular lower surface (opposing surface) whose outer diameter is larger than the diameter of the substrate W, and a downward discharge port 40 that opens at the center of the lower surface of the blocking plate 39. The blocking plate 39 is disposed below the support shaft 41. The support shaft 41 is supported by a support arm 42 that extends horizontally above the blocking plate 39.

  The processing unit 2 includes a blocking plate lifting / lowering unit 43 that lifts and lowers the blocking plate 39. The blocking plate lifting / lowering unit 43 moves the support arm 42 in the vertical direction, so that the lower surface of the blocking plate 39 is lowered to the height at which the scan nozzle such as the chemical solution nozzle 19 cannot enter between the substrate W and the blocking plate 39. The blocking plate 39 is moved up and down between a proximity position close to the upper surface and a retracted position (position shown in FIG. 1) above the proximity position. The blocking plate lifting / lowering unit 43 can position the blocking plate 39 at an arbitrary position (height) from the lower position to the upper position.

  The processing unit 2 includes an upper surface nozzle 44 that discharges the processing liquid downward via a downward discharge port 40 that opens at the center of the lower surface of the blocking plate 39. The processing unit 2 further includes an upper hot water pipe 45 that guides hot water (pure water having a temperature higher than normal temperature) having a temperature higher than normal temperature (for example, 50 to 90 ° C .; specifically, 80 ° C.) to the upper surface nozzle 44; An upper hot water valve 46 interposed in the hot water pipe 45, a heater (not shown) for raising the temperature of pure water supplied from the upper hot water pipe 45 to the upper surface nozzle 44 to a temperature higher than normal temperature, and a rinse liquid An upper rinse liquid pipe 47 that guides the liquid to the upper surface nozzle 44, and an upper rinse liquid valve 48 interposed in the upper rinse liquid pipe 47.

The processing unit 2 includes a cylindrical upper gas passage 49 formed by the outer peripheral surface of the upper surface nozzle 44 and the inner peripheral surface of the blocking plate 39, and an upper gas pipe 50 that guides nitrogen gas at room temperature to the upper gas passage 49. And an upper gas valve 51 interposed in the upper gas pipe 50. The upper gas flow path 49 is disposed above the downward discharge port 40 that opens on the opposing surface of the blocking plate 39.
FIG. 2 is a process diagram illustrating an example of a processing method performed by the processing unit 2. FIG. 3 is a schematic diagram illustrating a state of the substrate W when the process illustrated in FIG. 2 is performed. In the following, reference is made to FIG. 1 and FIG. Reference is made to FIG. 3 as appropriate.

When the substrate W is processed by the processing unit 2, a loading process (step S <b> 1 in FIG. 2) for loading the substrate W into the processing unit 2 is performed.
Specifically, the control device 3 opens the lower gas valve 17 and starts discharging nitrogen gas to the upward discharge port 14 of the spin base 6. Thereafter, the control device 3 controls the transport robot so that the substrate W held by the hand of the transport robot is placed on the plurality of chuck pins 7 in a state where the blocking plate 39 and the like are retracted. In addition, after the substrate W is placed on the plurality of chuck pins 7, the control device 3 causes the plurality of chuck pins 7 to grip the substrate W and retracts the hand of the transfer robot from the chamber 4.

Next, a chemical supply process (step S2 in FIG. 2) for supplying SC-1 as an example of the chemical to the upper surface of the substrate W is performed.
Specifically, the control device 3 causes the spin motor 8 to start rotating the substrate W so that the substrate W rotates at a liquid processing speed (for example, 800 rpm), and the chemical nozzle 19 is moved from the retracted position to the processing position. The chemical nozzle moving unit 21 is controlled to move and reciprocate between R = 0 and R = 150. Thereafter, the control device 3 opens the chemical liquid valve 23 and causes the chemical liquid nozzle 19 to start discharging SC-1. Thereby, SC-1 is supplied to the entire upper surface of the substrate W, and an SC-1 liquid film covering the entire upper surface of the substrate W is formed on the substrate W. When a predetermined time elapses after the chemical liquid valve 23 is opened, the control device 3 closes the chemical liquid valve 23 and causes the chemical nozzle 19 to finish discharging SC-1. Thereafter, the control device 3 moves the chemical nozzle 19 to the retracted position. While the chemical nozzle 19 is discharging SC-1, the control device 3 may stop the SC-1 liquid landing position on the upper surface of the substrate W at the central portion, or between the central portion and the peripheral portion. You may move it with.

Next, an upper surface rinsing liquid supply step (step S3 in FIG. 2) for supplying room temperature pure water, which is an example of a rinsing liquid, to the upper surface of the substrate W, and a lower surface of the substrate W, which is an example of a rinsing liquid, The lower surface rinsing liquid supply step (step S3 in FIG. 2) to be supplied to is performed in parallel.
Regarding the upper surface rinsing liquid supply process, the control device 3 controls the pure water nozzle moving unit 26 so that the pure water nozzle 24 moves from the retracted position to the processing position R = 0. Thereafter, the control device 3 opens the normal temperature pure water valve 28 and causes the pure water nozzle 24 to start discharging normal temperature pure water. Thereby, SC-1 adhering to the upper surface of the substrate W is washed away with pure water, and the entire upper surface of the substrate W is covered with a liquid film of pure water. When a predetermined time elapses after the room temperature pure water valve 28 is opened, the control device 3 closes the room temperature pure water valve 28 and causes the pure water nozzle 24 to finish discharging pure water.

  Regarding the lower surface rinsing liquid supply step, the control device 3 opens the lower room temperature pure water valve 11 and causes the lower surface nozzle 9 to start discharging normal temperature pure water. Thereby, the SC-1 mist and the like adhering to the lower surface of the substrate W are washed away with pure water. When a predetermined time elapses after the lower normal temperature valve is opened, the control device 3 closes the lower normal temperature pure water valve 11 and causes the lower surface nozzle 9 to finish discharging pure water. The control device 3 opens and closes the lower room temperature pure water valve 11 so that the lower surface nozzle 9 discharges pure water during at least a part of the period during which the pure water nozzle 24 discharges pure water.

Next, a liquid film forming step (step S4 in FIG. 2) is performed in which cold water, which is an example of a coagulation target liquid (a liquid to be frozen for freeze cleaning), is supplied to the upper surface of the substrate W.
Specifically, the control device 3 controls the spin motor 8 so that the substrate W rotates at a liquid film formation speed (for example, 150 rpm) smaller than the liquid processing speed. Further, the control device 3 opens the cold water valve 30 and causes the pure water nozzle 24 located at the processing position R = 0 to start discharging cold water. When a predetermined time elapses after the cold water valve 30 is opened, the control device 3 closes the cold water valve 30 and causes the pure water nozzle 24 to finish discharging pure water. Thereafter, the control device 3 moves the pure water nozzle 24 to the retracted position.

  The cold water discharged from the pure water nozzle 24 cools the substrate W and forms a liquid film covering the entire upper surface of the substrate W. At this time, the thickness of the liquid film of the cold water is adjusted to a size depending on a plurality of factors (such as the rotation speed of the substrate W, the surface tension of the liquid, and the surface state of the substrate W (whether it is hydrophobic)). As shown in FIG. 3A, the thickness of the outer peripheral portion of the liquid film covering the outer peripheral portion of the upper surface of the substrate W is larger than the thickness of the portion other than the outer peripheral portion of the liquid film. The thickness of the liquid film is, for example, 50 μm in the region inside the outer peripheral part of the liquid film, and is larger than that in the outer peripheral part of the liquid film.

Next, in succession to step S4, pure nitrogen covering the upper surface of the substrate W is discharged by discharging low-temperature nitrogen gas, which is an example of a cooling gas lower than the freezing point of the solidification target liquid, toward the upper surface of the substrate W. A freezing step (step S5 to step S7 in FIG. 2) for freezing the liquid film of water is performed.
(Step S5: Freezing the portion other than the outer peripheral portion of the liquid film) Specifically, the control device 3 causes the substrate W to rotate at a first freezing speed (for example, 50 rpm) smaller than the liquid film formation speed. The spin motor 8 is controlled. Furthermore, the control device 3 controls the cooling gas nozzle moving unit 33 so that the cooling gas nozzle 31 moves from the retracted position to the processing position (R = 60). Thereafter, the control device 3 opens the cooling gas valve 35 with the cooling gas nozzle 31 staying at that position, and causes the cooling gas nozzle 31 to discharge low temperature nitrogen gas at a flow rate of 90 liters / minute for 4 seconds. The supplied nitrogen gas spreads from directly under the cooling gas nozzle 31 to the surroundings, and the surrounding liquid film is frozen from the supply position. Then, the control device 3 moves the cooling gas nozzle 31 outward (in a direction away from the rotation axis A1) in a state in which the cooling gas nozzle 31 is discharging low-temperature nitrogen gas toward the upper surface of the substrate W, for 9 seconds. Therefore, it is moved to the position of R = 150. Thereby, the frozen part of the liquid film spreads outward, and the part other than the outer peripheral part of the liquid film freezes (see FIG. 3B).

When freezing the portion other than the outer peripheral portion of the liquid film, the control device 3 moves the supply position of the low-temperature nitrogen gas to the upper surface of the substrate W outward from the central portion R = 0 to the outer peripheral portion R = 150. May be.
(Step S6: Reducing the thickness of the outer peripheral portion of the liquid film) At the end of step S5, the control device 3 moves the supply position of the low-temperature nitrogen gas to the upper surface of the substrate W outward to reach the outer peripheral portion of the liquid film. . When the supply position of the low-temperature nitrogen gas reaches the outer peripheral portion of the liquid film, the inner portion of the liquid film is frozen and solidified, but the outer peripheral portion (generally R = about 140 to 150). Has not been frozen yet because of its thick liquid film. The control device 3 rotates the substrate W at a film thickness uniformizing speed (for example, 500 rpm) larger than the first freezing speed at the same time when the supply position of the low-temperature nitrogen gas to the liquid film reaches the outer periphery of the liquid film. In this way, the spin motor 8 is controlled to increase in speed. Due to this increased high-speed rotation, a part of the unfrozen liquid film on the outer periphery is shaken off from the substrate W, and the thickness of the liquid film thicker than 50 μm is reduced to 50 μm.

  (Step S7: Freezing of the outer peripheral portion of the liquid film) After the substrate W rotates for a predetermined time at the film thickness uniforming speed, the control device 3 keeps the supply position of the low-temperature nitrogen gas at the outer peripheral portion R = 150 of the liquid film. In this state, the spin motor 8 is controlled so that the substrate W rotates at a second freezing speed (for example, 50 rpm) smaller than the film thickness uniformization speed. Then, the control device 3 rotates the substrate W at the second freezing speed for 14 seconds while supplying nitrogen gas at a flow rate of 90 liters / minute. Thereby, the liquid film in the outer peripheral portion is also frozen. Thereafter, the control device 3 closes the cooling gas valve 35 and terminates the discharge of the low-temperature nitrogen gas to the cooling gas nozzle 31. Thereafter, the control device 3 moves the cooling gas nozzle 31 to the retracted position.

  Here, a supplementary description will be given of steps S6 and S7. The acceleration time for the rotation speed of the substrate W to increase from the first freezing speed to the film thickness uniformization speed is shorter than the constant speed rotation time during which the substrate W rotates at the film thickness uniformization speed. Similarly, the deceleration time during which the rotation speed of the substrate W decreases from the film thickness uniformization speed to the second freezing speed is shorter than the constant speed rotation time. The acceleration time is, for example, 0.5 seconds, and the deceleration time is, for example, 0.5 seconds. The constant speed rotation time is, for example, 1.0 second. The deceleration time may be longer than the acceleration time, but is preferably equal to or less than the acceleration time from the viewpoint of shortening the processing time.

  As shown in FIG. 3B, when the acceleration of the substrate W is started, the portion inside the outer peripheral portion of the liquid film is frozen and solidified, but the outer peripheral portion of the liquid film remains liquid. (Step S5 in FIG. 2). Therefore, as shown in FIG. 3C, the liquid on the substrate W is discharged by acceleration and high-speed rotation of the substrate W (step S6 in FIG. 2). Thereby, as shown in FIG.3 (d), the thickness of the outer peripheral part of a liquid film reduces, and the difference of the thickness of the outer peripheral part of a liquid film and the thickness of the center part of a liquid film becomes small. Since the supply position of the low-temperature nitrogen gas stays at the outer peripheral portion of the liquid film, the outer peripheral portion of the liquid film is frozen after the thickness is reduced (step S7 in FIG. 2). As a result, the entire liquid film is frozen. Therefore, as shown in FIG. 3E, a frozen film (liquid film after freezing) having a small difference in thickness between the central portion and the outer peripheral portion is formed on the substrate W.

Next, a frozen film removing step (FIG. 5) of thawing and removing the frozen film on the substrate W by discharging hot water, which is an example of a thawing solution having a temperature higher than the freezing point of the solidification target liquid, toward the upper surface of the substrate W. 2 step S8) is performed.
Specifically, the control device 3 controls the spin motor 8 so that the substrate W rotates at a frozen film removal speed (for example, 2000 rpm) larger than the freezing speed. Further, the control device 3 opens the upper gas valve 51 to start the discharge of nitrogen gas to the downward discharge port 40 of the blocking plate 39. Further, the control device 3 controls the shielding plate lifting / lowering unit 43 so that the shielding plate 39 moves from the retracted position to the processing position. Thereafter, the control device 3 opens the upper hot water valve 46 and causes the upper surface nozzle 44 to start discharging hot water at 80 ° C. The frozen film on the substrate W is thawed by supplying hot water and discharged from the substrate W to the periphery thereof. Thereby, the entire upper surface of the substrate W is covered with hot water. When a predetermined time elapses after the upper hot water valve 46 is opened, the control device 3 closes the upper hot water valve 46 and causes the upper surface nozzle 44 to finish discharging hot water.

Next, a final rinsing liquid supply step (step S9 in FIG. 2) for supplying pure water at room temperature, which is an example of a rinsing liquid, to the upper surface of the substrate W is performed.
Specifically, the control device 3 controls the spin motor 8 so that the substrate W rotates at a final rinse speed (for example, 500 rpm) smaller than the frozen film removal speed. Thereafter, the control device 3 opens the upper rinse liquid valve 48 in a state where the blocking plate 39 is located at the processing position, and causes the upper surface nozzle 44 to start discharging pure water at room temperature. As a result, the pure water liquid film on the substrate W is replaced with the pure water discharged from the upper surface nozzle 44, and a pure water liquid film covering the entire upper surface of the substrate W is formed. When a predetermined time elapses after the upper rinse liquid valve 48 is opened, the control device 3 closes the upper rinse liquid valve 48 and causes the upper surface nozzle 44 to finish discharging pure water.

Next, a drying process (step S10 in FIG. 2) for drying the substrate W by high-speed rotation of the substrate W is performed.
Specifically, the control device 3 has a drying speed (for example, higher than the final rinse speed) in a state where the blocking plate 39 is close to the upper surface of the substrate W and the downward discharge port 40 is discharging nitrogen gas. The spin motor 8 is controlled so that the substrate W rotates at 2500 rpm. Thereby, a large centrifugal force is applied to the liquid adhering to the substrate W, and the liquid is shaken off from the substrate W to the periphery thereof. Therefore, the liquid is removed from the substrate W, and the substrate W is dried. When a predetermined time elapses after the high-speed rotation of the substrate W is started, the control device 3 causes the spin motor 8 to stop the rotation of the substrate W.

Next, an unloading step (Step S11 in FIG. 2) for unloading the substrate W from the processing unit 2 is performed.
Specifically, the control device 3 controls the shield plate lifting / lowering unit 43 so that the shield plate 39 moves to the retracted position. Further, the control device 3 closes the upper gas valve 51 and the lower gas valve 17 to end the discharge of nitrogen gas from the downward discharge port 40 and the upward discharge port 14. Further, the control device 3 causes the plurality of chuck pins 7 to release the grip of the substrate W. In this state, the control device 3 causes the hand of the transfer robot to enter the chamber 4. Then, the control device 3 holds the substrate W on the plurality of chuck pins 7 in the hand of the transfer robot. Thereafter, the control device 3 and the hand of the transfer robot are retracted from the chamber 4. Thereby, the processed substrate W is unloaded from the chamber 4.

  As described above, in the present embodiment, the liquid film that covers the upper surface of the substrate W is formed. And after freezing parts other than the outer peripheral part of a liquid film, the thickness of the outer peripheral part of a liquid film is reduced. Thereafter, the outer periphery of the liquid film is frozen. As a result, the entire liquid film is frozen, and a frozen film covering the upper surface of the substrate W is formed. In order to ensure a high particle removal rate in freeze cleaning, it is necessary to adjust the thickness of the liquid film within a predetermined range, and the particle removal rate decreases regardless of whether the thickness of the liquid film is larger or smaller than that range. . As described above, since the thickness of the outer peripheral portion of the liquid film is reduced, the difference between the thickness of the outer peripheral portion of the liquid film and the thickness of the central portion of the liquid film is reduced, and the uniformity of the film thickness is increased. For this reason, the thickness of the frozen membrane can be set within the optimum range over the entire area. Thereby, the particle removal rate can be increased. FIG. 4 shows the difference in particle removal rate (PRE) of the substrate W processed by the prior art method and the method of the above embodiment of the present invention. According to the prior art, the removal rate is reduced at R> 145, but according to the method of the present invention, the reduction of the removal rate is remarkably improved.

  Next, a modification of the above processing method will be described. In the above embodiment, at the end of step S5, the cooling gas nozzle 31 reaches the outer periphery of the substrate W, and at the same time, the spin motor 8 is controlled to be accelerated to a film thickness uniformizing speed larger than the first freezing speed. Further, after the cooling gas nozzle 31 reaches the outer peripheral portion of the substrate W, the spin motor 8 may be controlled to increase in speed after a predetermined time has elapsed. For example, when the speed of the spin motor 8 is controlled to increase after about 3 seconds, the outer periphery of the substrate W is cooled during that time, and the time until the outer periphery of the liquid film is frozen in the subsequent step S7 is set. It can be shortened to about 11 seconds.

Although the description of the embodiment of the present invention has been described above, the present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the present invention.
For example, in the above-described embodiment, the case of accelerating the substrate W in the rotation direction when reducing the thickness of the outer peripheral portion of the liquid film has been described. However, a gas (for example, nitrogen gas) is directed toward the upper peripheral portion of the substrate W. The thickness of the outer peripheral portion of the liquid film may be reduced by discharging an inert gas).

  In the above-described embodiment, the case where the supply flow rate of the cooling gas (low-temperature nitrogen gas) to the upper surface of the substrate W is constant has been described. However, the substrate W has a larger flow rate than when the discharge of the cooling gas is started. A cooling gas may be supplied to the outer peripheral portion of the upper surface (the outer peripheral portion of the liquid film). In this case, since the outer peripheral portion of the liquid film can be frozen in a shorter time, the processing time of the substrate W can be shortened. Specifically, for example, in step S7 of the above embodiment, nitrogen gas was supplied at a flow rate of 90 liters / minute for 14 seconds. At this time, by increasing the flow rate of nitrogen gas to 150 liters / minute, The time until freezing in this step S7 can be shortened to about 6 seconds.

  In the above-described embodiment, the case where the chemical solution is SC-1 has been described. However, the chemical solution is sulfuric acid, acetic acid, nitric acid, hydrochloric acid, hydrofluoric acid, aqueous ammonia, hydrogen peroxide solution, organic acid (for example, citric acid, oxalic acid). Etc.), an organic alkali (for example, TMAH: tetramethylammonium hydroxide, etc.), a surfactant, and a liquid containing at least one of a corrosion inhibitor.

In the above-described embodiment, the case where the rinse liquid is pure water has been described. However, the rinse liquid is carbonated water, electrolytic ion water, hydrogen water, ozone water, IPA (isopropyl alcohol), and dilution concentration (for example, 10 Or about 100 ppm of hydrochloric acid water. IPA is an example of a volatile solvent that is more volatile than water.
Moreover, although the above-mentioned embodiment demonstrated the case where the pure water nozzle 24 discharges the pure water and cold water of normal temperature, the nozzle for exclusive use which discharges the cold water which is an example of the coagulation target liquid (coagulation target liquid nozzle) May be provided. In this case, the coagulation target liquid nozzle may be attached to a dedicated nozzle arm, or may be attached to a nozzle arm for another nozzle.

  Further, two or more of all the embodiments described above may be combined.

1: Substrate processing device 3: Control device (control means)
5: Spin chuck (substrate holding means)
8: Spin motor (means for uniform film thickness)
24: Pure water nozzle (liquid film forming means)
28: Room temperature pure water valve (liquid film forming means)
30: Cold water valve (liquid film forming means)
31: Cooling gas nozzle (freezing means)
35: Cooling gas valve (freezing means)
36: Cooling gas flow rate adjustment valve (freezing means)
W: Substrate

Claims (3)

A liquid film forming step of forming a liquid film covering the upper surface of the substrate;
A freezing step of freezing the liquid film after the liquid film forming step,
The freezing step includes
After the liquid film forming step, a first freezing step of freezing a portion other than the outer peripheral portion of the liquid film;
After the first freezing step, by reducing the thickness of the outer peripheral portion of the liquid film, the film thickness equalizing step for reducing the difference between the thickness of the outer peripheral portion of the liquid film and the thickness of the central portion of the liquid film When,
A substrate processing method including a second freezing step of freezing an outer peripheral portion of the liquid film after the film thickness uniformizing step.   The substrate processing method according to claim 1, wherein the film thickness uniforming step includes an acceleration step of accelerating the substrate in a direction around a rotation axis passing through a central portion of the substrate. Substrate holding means for holding the substrate;
A liquid film forming means for forming a liquid film covering an upper surface of the substrate held by the substrate holding means;
Freezing means for freezing the liquid film;
A film thickness uniformizing means for reducing the thickness of the outer peripheral portion of the liquid film;
Control means for controlling the liquid film forming means, freezing means, and film thickness uniformizing means,
The control means performs a liquid film forming step for forming a liquid film covering the upper surface of the substrate, and a freezing step for freezing the liquid film after the liquid film forming step,
The freezing step includes
After the liquid film forming step, a first freezing step of freezing a portion other than the outer peripheral portion of the liquid film;
After the first freezing step, by reducing the thickness of the outer peripheral portion of the liquid film, the film thickness equalizing step for reducing the difference between the thickness of the outer peripheral portion of the liquid film and the thickness of the central portion of the liquid film When,
A substrate processing apparatus comprising: a second freezing step of freezing an outer peripheral portion of the liquid film after the film thickness uniformizing step.

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