Substrate cleaning method and substrate cleaning device

Abstract

The present invention provides a substrate cleaning method, which includes the following steps: supplying a mixed gas of a cluster-forming gas that forms clusters through adiabatic expansion and a carrier gas with a smaller molecular weight or atomic weight than the cluster-forming gas to a nozzle; forming the clusters by ejecting the mixed gas from the nozzle; removing particles attached to the substrate through the clusters; and continuing to supply the carrier gas to the nozzle during a set time from the time when the supply of the cluster-forming gas to the nozzle ends.

Description

Technical Field

[0001] The present disclosure relates to a substrate cleaning method and a substrate cleaning device. Background Art

[0002] The substrate cleaning method described in Patent Document 1 includes the steps of: forming clusters of chlorine trifluoride by spraying a mixed gas of chlorine trifluoride gas and argon gas from a nozzle; and causing the formed clusters to collide with the surface of single crystal silicon.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-46001 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] One embodiment of the present disclosure provides a technology capable of suppressing the generation of defects on a substrate when spraying a mixed gas of a cluster forming gas and a carrier gas toward a substrate ends.

[0008] Solutions for solving problems

[0009] A substrate cleaning method according to one embodiment of the present disclosure includes the following steps:

[0010] supplying a mixed gas of a cluster forming gas that forms clusters by adiabatic expansion and a carrier gas having a smaller molecular weight or atomic weight than the cluster forming gas to a nozzle;

[0011] forming the clusters by ejecting the mixed gas from the nozzle;

[0012] removing particles attached to the substrate by using the clusters; and

[0013] From the time when the supply of the cluster forming gas to the nozzle is ended, the supply of the carrier gas to the nozzle is continued for a set time period.

[0014] Effects of the Invention

[0015] According to one embodiment of the present disclosure, when a mixed gas of a cluster forming gas and a carrier gas is sprayed toward a substrate, generation of defects on the substrate can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a side view showing a substrate cleaning device according to one embodiment.

[0017] Figure 2 It is a top view showing a nozzle moving mechanism according to one embodiment.

[0018] Figure 3 It is a cross-sectional view showing the formation of a cluster according to one embodiment.

[0019] Figure 4 This is a diagram showing the components of a control unit according to one embodiment using functional blocks.

[0020] Figure 5 1 is a flowchart showing a substrate cleaning method according to one embodiment.

[0021] Figure 6 It is a diagram showing the operation timing of the substrate cleaning device involved in one embodiment.

[0022] Figure 7 It is a figure which shows the contamination state of the substrate after cleaning which concerns on Example.

[0023] Figure 8 It is a diagram showing the contamination state of a substrate after cleaning according to a conventional example. DETAILED DESCRIPTION

[0024] Below, the embodiments of the present disclosure are described with reference to the accompanying drawings. In addition, sometimes the same or corresponding structures are marked with the same or corresponding figure marks in each drawing, and the description is omitted. In the following description, the X-axis direction, the Y-axis direction, and the Z-axis direction are mutually perpendicular directions, the X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is a vertical direction. In addition, the bottom refers to the vertical downward direction (negative direction of the Z-axis), and the top refers to the vertical upward direction (positive direction of the Z-axis).

[0025] Figure 1 1 is a side view showing a substrate cleaning device according to an embodiment. The substrate cleaning device 10 removes particles 5 attached to the main surface 3 of the substrate 2 by ejecting gas toward the main surface 3 of the substrate 2 (see Figure 3 The substrate 2 is, for example, a semiconductor substrate such as a silicon wafer. The substrate cleaning device 10 includes a processing container 20, a substrate holding portion 30, a rotating shaft portion 34, a rotating driving portion 36, a lifting driving portion 38, a nozzle 40, a driving portion 50, a gas supply portion 60, a gas suction portion 70, and a control portion 90.

[0026] The processing container 20 has a space for processing the substrate 2. The processing container 20 has a cylindrical space, for example. The processing container 20 has a gate (not shown) as a loading and unloading port for the substrate 2 and a gate valve (not shown) for opening and closing the gate.

[0027] The substrate holder 30 is disposed inside the processing container 20 and has a substrate holding surface 31 for holding the substrate 2. The substrate holder 30 holds the substrate 2 horizontally with, for example, the main surface 3 of the substrate 2 from which particles are to be removed facing upward.

[0028] The rotating shaft 34 extends downward from the center of the substrate holding portion 30 and is vertically arranged. The upper end of the rotating shaft 34 is arranged inside the processing container 20 , and the lower end of the rotating shaft 34 is arranged outside the processing container 20 .

[0029] The rotation drive unit 36 ​​rotates the substrate holding unit 30 by rotating the rotation shaft unit 34 about the vertical axis. The rotation drive unit 36 ​​includes, for example, a rotation motor and a transmission mechanism that transmits the rotational driving force of the rotation motor to the rotation shaft unit 34 .

[0030] The lifting drive unit 38 lifts the substrate holding unit 30. The lifting drive unit 38 is formed of, for example, a fluid pressure cylinder. The lifting drive unit 38 lifts the substrate holding unit 30 via the rotation drive unit 36, but the substrate holding unit 30 may be lifted or lowered without the rotation drive unit 36.

[0031] The nozzle 40 sprays gas toward the main surface 3 of the substrate 2 held by the substrate holding portion 30. The nozzle 40 is disposed above the substrate holding portion 30 so that a spray port 41 of the gas faces downward.

[0032] The nozzle 40 sprays gas in a direction perpendicular to the main surface 3 of the substrate 2 held by the substrate holding portion 30 (e.g., vertical direction). Since the gas hits the main surface 3 of the substrate 2 perpendicularly, the pattern collapse of the concave-convex pattern previously formed on the main surface 3 of the substrate 2 can be suppressed.

[0033] The driving unit 50 moves the nozzle 40 in the radial direction of the substrate holding unit 30. The driving unit 50 moves the nozzle 40 between a position directly above the center of the substrate holding unit 30 and a position directly above the outer periphery of the substrate holding unit 30. In addition, the driving unit 50 moves the nozzle 40 to a position radially outward of the substrate holding unit 30. The position radially outward of the substrate holding unit 30 is a standby position for standby when no gas is sprayed.

[0034] Figure 2 FIG. 2 is a top view showing a driving unit according to an embodiment of the present invention. Figure 2 As shown, the driving unit 50 includes, for example, a rotating arm 51 and a rotating driving unit 52 for rotating the rotating arm 51. The rotating arm 51 is horizontally arranged, and the nozzle 40 is held at the front end of the rotating arm 51 in a manner that the injection port 41 of the nozzle 40 faces downward. The rotating driving unit 52 rotates the rotating arm 51 around a rotating shaft 53 extending downward from the base end of the rotating arm 51.

[0035] In addition, the driving unit 50 may include a guide rail and a linear motion mechanism instead of the rotation arm 51 and the rotation driving unit 52. The guide rail is arranged horizontally, and the linear motion mechanism moves the nozzle 40 along the guide rail.

[0036] like Figure 1 As shown, the driving unit 50 may further include a lifting driving unit 54 for lifting the nozzle 40. The lifting driving unit 54 is constituted by, for example, a fluid pressure cylinder. The lifting driving unit 54 lifts the nozzle 40 via the rotation driving unit 52, but the nozzle 40 may be lifted or lowered without the rotation driving unit 52.

[0037] The gas supply unit 60 supplies the cluster forming gas to the nozzle 40. The cluster forming gas is ejected from the nozzle 40. The cluster forming gas is adiabatically expanded inside the processing container 20 which has been depressurized in advance, and is thus cooled to a condensation temperature to form clusters 4 which are aggregates of molecules or atoms. The cluster forming gas includes, for example, at least one gas selected from carbon dioxide (CO2) gas and argon (Ar) gas.

[0038] In addition, the gas supply unit 60 supplies a carrier gas to the nozzle 40. The carrier gas has a smaller molecular weight or atomic weight than the cluster forming gas. Therefore, the carrier gas has a higher condensation temperature than the cluster forming gas. Therefore, the carrier gas does not form clusters 4. The carrier gas includes, for example, at least one gas selected from hydrogen (H2) gas and helium (He) gas.

[0039] The gas supply unit 60 supplies a mixed gas of a cluster forming gas and a carrier gas to the nozzle 40. In this embodiment, CO2 gas is used as the cluster forming gas, and H2 gas is used as the carrier gas. In addition, the combination of the cluster forming gas and the carrier gas is not particularly limited.

[0040] The gas supply unit 60 includes a common line L1 whose downstream end is connected to the nozzle 40, a first branch line L2 extending from the upstream end of the common line L1 to a first supply source 61, and a second branch line L3 extending from the upstream end of the common line L1 to a second supply source 62. The first supply source 61 is a supply source of CO2 gas. In addition, the second supply source 62 is a supply source of H2 gas.

[0041] The common line L1 is provided with a pressure regulator 63 for regulating the supply pressure P of the gas supplied to the nozzle 40. The pressure regulator 63 regulates the supply pressure P of the gas supplied to the nozzle 40 under the control of the control unit 90. In addition, a pressure booster such as a gas booster may be further provided on the upstream side of the pressure regulator 63 in the common line L1.

[0042] The first branch line L2 is provided with a first on-off valve 64 and a first flow rate regulating valve 65. When the control unit 90 opens the first on-off valve 64, CO2 gas is supplied from the first supply source 61 to the nozzle 40. During this period, the control unit 90 adjusts the flow rate of CO2 gas through the first flow rate regulating valve 65. When the control unit 90 closes the first on-off valve 64, the supply of CO2 gas from the first supply source 61 to the nozzle 40 is stopped.

[0043] The second branch line L3 is provided with a second on-off valve 66 and a second flow rate regulating valve 67. When the control unit 90 opens the second on-off valve 66, H2 gas is supplied from the second supply source 62 to the nozzle 40. During this period, the control unit 90 adjusts the flow rate of H2 gas through the second flow rate regulating valve 67. When the control unit 90 closes the second on-off valve 66, the supply of H2 gas from the second supply source 62 to the nozzle 40 is stopped.

[0044] The gas suction unit 70 reduces the pressure inside the processing container 20. The gas suction unit 70 includes, for example, a suction pump 71 that sucks gas inside the processing container 20, a suction line 72 that extends from a suction port 27 formed on the inner wall surface 22 of the processing container 20 to the suction pump 71, and a pressure regulator 73 that is provided in the middle of the suction line 72. The pressure regulator 73 adjusts the gas pressure inside the processing container 20 under the control of the control unit 90.

[0045] Figure 3 4 is a cross-sectional view showing the formation of a cluster according to one embodiment. The nozzle 40 is, for example, a nozzle generally called a Laval nozzle, and has a neck 43 having a smaller diameter than both the injection port 41 and the supply port 42. The nozzle 40 has a tapered hole 45 between the neck 43 and the injection port 41, the diameter of which increases as it moves from the neck 43 toward the injection port 41.

[0046] The nozzle 40 is disposed inside the processing container 20. The inside of the processing container 20 is depressurized in advance by the gas suction unit 70. The gas supplied to the supply port 42 of the nozzle 40 is accelerated by passing through the neck 43 and is ejected from the ejection port 41. The ejected CO2 gas is adiabatically expanded inside the processing container 20 that has been depressurized in advance, and is therefore cooled to the condensation temperature. As a result, the CO2 molecules are bonded to each other by van der Waals forces to form a cluster 4 that is an aggregate of CO2 molecules.

[0047] The cluster 4 collides with the particles 5 attached to the main surface 3 of the substrate 2 to blow away the particles 5. Even if the cluster 4 collides with the main surface 3 without directly colliding with the particles 5, the particles 5 around the collision position can be blown away. In addition, the cluster 4 becomes high temperature by the collision, so it is crushed and decomposed, and is attracted by the gas attraction unit 70.

[0048] In addition, when the size of the cluster 4 is too small, the removal efficiency of the particles 5 is too low. On the other hand, when the size of the cluster 4 is too large, the concave-convex pattern pre-formed on the main surface 3 of the substrate 2 collapses. In addition, when the size of the cluster 4 is too large, spot-like defects will also be generated on the main surface 3 of the substrate 2.

[0049] Therefore, the size of the cluster 4 is adjusted. The size of the cluster 4 can be adjusted by, for example, the supply pressure P of the gas supplied to the nozzle 40, the flow ratio of the cluster forming gas to the carrier gas, and the gas pressure inside the processing container 20. The supply pressure P of the gas supplied to the nozzle 40 is, for example, 0.5MPa to 5Mpa, preferably 0.5MPa to 0.9MPa. The flow ratio of the cluster forming gas to the carrier gas is, for example, 10:90 to 90:10. The flow rate refers to the normal flow rate (unit: slm) measured at 0°C and atmospheric pressure. The temperature of the nozzle 40 is, for example, -50°C to -10°C. The gas pressure inside the processing container 20 is, for example, 5Pa to 120Pa.

[0050] The control unit 90 is constituted by, for example, a computer, and includes a CPU (Central Processing Unit) 91 and a storage medium 92 such as a memory. The storage medium 92 stores a program for controlling various processes executed in the substrate cleaning device 10. The control unit 90 controls the operation of the substrate cleaning device 10 by causing the CPU 91 to execute the program stored in the storage medium 92. In addition, the control unit 90 includes an input interface 93 and an output interface 94. The control unit 90 receives signals from the outside through the input interface 93 and sends signals to the outside through the output interface 94.

[0051] The program may also be stored in a computer-readable storage medium and installed from the storage medium to the storage medium 92 of the control unit 90. Examples of computer-readable storage media include a hard disk (HD), a floppy disk (FD), a compact disk (CD), a magneto-optical disk (MO), a memory card, etc. In addition, the program may be downloaded from a server via the Internet and installed to the storage medium 92 of the control unit 90.

[0052] Figure 4 This is a diagram showing the components of a control unit according to one embodiment using functional blocks. Figure 4 The functional blocks shown in the figure are conceptual and do not necessarily need to be physically configured as shown. All or part of each functional block can be functionally or physically dispersed / combined in arbitrary units to form a structure. All or any part of each processing function performed by each functional block can be implemented by a program executed by a CPU, or can be implemented as hardware based on wiring logic.

[0053] like Figure 4As shown, the control unit 90 includes a gas supply control unit 95, a heater control unit 96, a refrigerant supply control unit 97, and a relative position control unit 98. The gas supply control unit 95 controls the gas supply unit 60. The gas supply unit 60 supplies the cluster forming gas and the carrier gas to the nozzle 40. The heater control unit 96 controls the heater 80. The heater 80 heats the nozzle 40. The heater 80 is, for example, an electric heating wire arranged inside the nozzle 40. The refrigerant supply control unit 97 controls the refrigerant supply unit 81. The refrigerant supply unit 81 adjusts the temperature of the nozzle 40 by supplying refrigerant to the nozzle 40. A flow path for the refrigerant to flow is formed around the nozzle 40. The refrigerant can be either a gas or a liquid. The temperature of the refrigerant is lower than the room temperature. When the refrigerant supply control unit 97 prohibits the refrigerant from being supplied to the nozzle 40, the temperature of the nozzle 40 naturally rises even if the nozzle 40 is not heated. The relative position control unit 98 controls the drive unit 50. The driving unit 50 moves the relative position of the nozzle 40 and the substrate holding unit 30 between a position where the gas is ejected from the nozzle 40 toward the substrate 2 and a position where the gas is ejected from the nozzle 40 toward the outside of the substrate 2 .

[0054] Figure 5 1 is a flowchart showing a substrate cleaning method according to one embodiment. Figure 5 Each of the steps shown is performed under the control of the control unit 90 .

[0055] The substrate cleaning method includes a step S101 of carrying a substrate 2 into a processing container 20. In the step S101, a transport device (not shown) carries the substrate 2 from the outside of the processing container 20 into the processing container 20, and arranges the carried substrate 2 on the substrate holding surface 31 of the substrate holding portion 30. The substrate holding portion 30 holds the substrate 2 horizontally with the main surface 3 of the substrate 2 facing upward.

[0056] The substrate cleaning method includes a step S102 of supplying a mixed gas of a cluster forming gas and a carrier gas to the nozzle 40. In the step S102, the gas supply unit 60 supplies the mixed gas to the nozzle 40. The cluster forming gas is, for example, CO2 gas, and the carrier gas is, for example, H2 gas. The carrier gas suppresses liquefaction of the cluster forming gas inside the nozzle 40 and increases the supply pressure P of the gas supplied to the nozzle 40 to a desired gas pressure.

[0057] When the supply pressure P is too low, the adiabatic expansion of the cluster-forming gas, that is, the acceleration of the cluster-forming gas, is insufficient, and the clusters 4 do not grow to a size sufficient to remove the particles 5. On the other hand, when the supply pressure P is increased to a desired pressure only by the cluster-forming gas, the pressure of the cluster-forming gas exceeds the saturated vapor pressure, and the cluster-forming gas is liquefied inside the nozzle 40.

[0058] The carrier gas suppresses the liquefaction of the cluster forming gas inside the nozzle 40 by reducing the partial pressure of the cluster forming gas. In addition, the carrier gas can sufficiently accelerate the cluster forming gas by increasing the supply pressure P of the gas supplied to the nozzle 40 to the desired gas pressure, thereby enabling the clusters 4 to grow to a size sufficient to remove the particles 5.

[0059] While the gas supply unit 60 supplies the mixed gas to the nozzle 40 , the gas suction unit 70 suctions the gas inside the processing container 20 to maintain the gas pressure inside the processing container 20 at a constant level.

[0060] The substrate cleaning method includes a step S103 of forming clusters 4 by spraying a mixed gas from a nozzle 40. The CO2 gas included in the mixed gas is adiabatically expanded in the interior of the processing container 20 which has been depressurized in advance, and is therefore cooled to a condensation temperature. As a result, CO2 molecules are bonded to each other by van der Waals forces to form clusters 4 which are aggregates of CO2 molecules.

[0061] The substrate cleaning method includes a step S104 of removing particles 5 attached to the main surface 3 of the substrate 2 by the clusters 4. The clusters 4 collide with the particles 5 to blow away the particles 5. Even if the clusters 4 collide with the main surface 3 in a manner not directly colliding with the particles 5, the particles 5 around the collision position can be blown away.

[0062] The above-mentioned steps S102 to S104 are repeatedly performed while changing the position where the cluster 4 collides with the main surface 3 of the substrate 2. For example, the change is performed by the drive unit 50 moving the nozzle 40 in the radial direction of the substrate 2 while the substrate holding unit 30 is rotated by the rotation drive unit 36. The cluster 4 can collide with the entire main surface 3 of the substrate 2, so that the entire main surface 3 of the substrate 2 can be cleaned.

[0063] In addition, in the present embodiment, the substrate holding part 30 is rotated and the nozzle 40 is moved in the radial direction of the substrate 2, thereby changing the position where the cluster 4 hits the main surface 3 of the substrate 2, but the technology disclosed in the present invention is not limited to this. For example, the substrate holding part 30 can be moved in the X-axis direction and the Y-axis direction while the nozzle 40 is fixed.

[0064] After the above-mentioned steps S102 to S104 , a step of ending the supply of the cluster forming gas to the nozzle 40 (step S105 ) and a step of ending the supply of the carrier gas to the nozzle 40 (step S107 ) are performed.

[0065] The substrate cleaning method includes a step S105 of ending the supply of the cluster forming gas to the nozzle 40. In the step S105, the gas supply control unit 95 closes the first opening and closing valve 64 to end the supply of the cluster forming gas to the nozzle 40. At this time, the gas supply control unit 95 does not close the second opening and closing valve 66, but continues to open the second opening and closing valve 66.

[0066] The substrate cleaning method includes a step S106 of continuing to supply a carrier gas to the nozzle 40 during a set time Δt from the time when the supply of the cluster forming gas to the nozzle 40 is finished. In the step S106, the gas supply control unit 95 continues to open the second on-off valve 66 to continue to supply the carrier gas to the nozzle 40. Thus, the cluster forming gas remaining inside the nozzle 40 can be replaced with the carrier gas. The set time Δt is predetermined by experiments, etc., so that the cluster forming gas is not liquefied inside the nozzle 40, that is, the partial pressure of the cluster forming gas is sufficiently lower than the saturated vapor pressure as described later.

[0067] The substrate cleaning method includes a step S107 of ending the supply of the carrier gas to the nozzle 40. In the step S107, the gas supply control unit 95 closes the second on-off valve 66 to end the supply of the carrier gas to the nozzle 40. The gas supply control unit 95 ends the supply of the carrier gas to the nozzle 40 after replacing the cluster forming gas remaining inside the nozzle 40 with the carrier gas.

[0068] The substrate cleaning method includes a step S108 of carrying out the substrate 2 from the inside of the processing container 20 to the outside of the processing container 20. In the step S108, the substrate holding portion 30 releases the holding of the substrate 2, and the unillustrated conveying device receives the substrate 2 from the substrate holding portion 30 and carries the received substrate 2 out of the processing container 20. Thereafter, the current processing is completed.

[0069] Conventionally, the supply of the cluster forming gas to the nozzle 40 (step S105 ) and the supply of the carrier gas to the nozzle 40 (step S107 ) are terminated at the same time. This is one of the causes of the generation of spot-shaped defects on the main surface 3 of the substrate 2 .

[0070] When the supply of the cluster forming gas is terminated (step S105) and the supply of the carrier gas is terminated (step S107) at the same time, the carrier gas leaves the nozzle 40 earlier than the cluster forming gas. This is because the molecular weight or atomic weight of the carrier gas is smaller than that of the cluster forming gas.

[0071] Since the carrier gas leaves the nozzle 40 earlier than the cluster forming gas, the proportion of the cluster forming gas in the internal space of the nozzle 40 increases. As a result, in the internal space of the nozzle 40, the cluster forming gas or impurities inevitably included in the cluster forming gas may liquefy.

[0072] When the liquefied gas is ejected from the nozzle 40, it adheres to the main surface 3 of the substrate 2. The adhered matter becomes a spot-like defect. In addition, there is the following problem: when the cluster-forming gas or its impurities are liquefied inside the nozzle 40, a huge cluster 4 is formed, which causes the concave-convex pattern of the main surface 3 of the substrate 2 to collapse.

[0073] The substrate cleaning method of this embodiment terminates the supply of the carrier gas (step S107) after the supply of the cluster forming gas is terminated (step S105). That is, the substrate cleaning method of this embodiment includes step S106 of continuing to supply the carrier gas to the nozzle 40 for a set time Δt after the supply of the cluster forming gas is terminated.

[0074] According to this embodiment, after the cluster forming gas remaining inside the nozzle 40 is replaced with the carrier gas, the supply of the carrier gas to the nozzle 40 is stopped. As a result, it is possible to suppress the generation of spot-like defects on the main surface 3 of the substrate 2. In addition, it is possible to suppress the collapse of the concavo-convex pattern on the main surface 3 of the substrate 2.

[0075] Figure 6 2 is a diagram showing the operation timing of the substrate cleaning apparatus according to one embodiment. For example, the gas supply control unit 95 starts supplying both the cluster forming gas and the carrier gas to the nozzle 40 at time t0.

[0076] The gas supply control unit 95 supplies both the cluster forming gas and the carrier gas to the nozzle 40 from time t0 to time t1. The gas supply control unit 95 supplies the carrier gas to the nozzle 40 at the first flow rate FR1 from time t0 to time t1.

[0077] Furthermore, the heater control unit 96 prohibits heating of the nozzle 40 by the heater 80 from time t0 to time t1. Thus, the nozzle 40 can be cooled to a temperature close to the condensation temperature of the cluster forming gas, and the formation of the clusters 4 can be assisted.

[0078] The refrigerant supply control unit 97 supplies the refrigerant to the nozzle 40 from time t0 to time t1. Thus, the nozzle 40 can be cooled to a temperature close to the condensation temperature of the cluster forming gas, and the formation of the clusters 4 can be assisted.

[0079] Thereafter, at time t1, the gas supply control unit 95 stops supplying the cluster forming gas to the nozzle 40. Next, the gas supply control unit 95 continues supplying the carrier gas to the nozzle 40 from time t1 to time t2. The time from time t1 to time t2 is the set time Δt.

[0080] The gas supply control unit 95 supplies the carrier gas to the nozzle 40 at a second flow rate FR2 (FR2>FR1) greater than the first flow rate FR1 from time t1 to time t2. Thus, the cluster forming gas remaining in the nozzle 40 can be quickly replaced with the carrier gas.

[0081] In addition, the timing of switching the flow rate of the carrier gas from the first flow rate FR1 to the second flow rate FR2 may not be time t1, and the timing may be a time just before time t1 or a time after time t1. The gas supply control unit 95 only needs to supply the carrier gas to the nozzle 40 at the second flow rate FR2 during the set time Δt. The cluster forming gas remaining inside the nozzle 40 can be quickly replaced with the carrier gas.

[0082] The heater control unit 96 heats the nozzle 40 with the heater 80 from time t1 to time t2. Since heat is supplied to the nozzle 40, the temperature of the nozzle 40 becomes high. As a result, the cluster forming gas or its impurities can be suppressed from liquefying inside the nozzle 40.

[0083] In addition, the timing for starting to heat the nozzle 40 may not be time t1, but may be a time just before time t1 or a time after time t1. The heater control unit 96 may heat the nozzle 40 by the heater 80 during the set time Δt. Since heat is supplied to the nozzle 40, the temperature of the nozzle 40 becomes high. As a result, the cluster forming gas or its impurities can be suppressed from liquefying inside the nozzle 40.

[0084] The refrigerant supply control unit 97 prohibits the supply of refrigerant to the nozzle 40 from time t1 to time t2. Since the refrigerant is not supplied to the nozzle 40, the temperature of the nozzle 40 becomes high. As a result, the cluster forming gas or its impurities can be suppressed from liquefying inside the nozzle 40.

[0085] In addition, the timing for ending the supply of the refrigerant may not be time t1, but may be a time just before time t1 or a time after time t1. The refrigerant supply control unit 97 may prohibit the supply of the refrigerant to the nozzle 40 during the set time Δt. Since the refrigerant is not supplied to the nozzle 40, the temperature of the nozzle 40 naturally becomes high even if the nozzle 40 is not heated. As a result, the cluster forming gas or its impurities can be suppressed from liquefying inside the nozzle 40.

[0086] The relative position control unit 98 makes the relative position of the nozzle 40 and the substrate 2 be at a position where the gas is ejected from the nozzle 40 toward the substrate 2 from time t1 to time t2. If the relative position of the nozzle 40 and the substrate 2 is made to be at a position where the gas is ejected from the nozzle 40 toward the outside of the substrate 2 from time t1 to time t2, the gas collides with the inner wall surface of the processing container 20. As a result, the deposits attached to the inner wall surface of the processing container 20 are peeled off. Sometimes the peeled deposits fly up and adhere to the main surface 3 of the substrate 2.

[0087] In this embodiment, the relative position control unit 98 makes the relative position of the nozzle 40 and the substrate 2 be at a position where the gas is ejected from the nozzle 40 toward the substrate 2 from time t1 to time t2. The gas ejected from the nozzle 40 collides with the substrate 2, thereby reducing the flow rate. The gas with a low flow rate collides with the inner wall surface of the processing container 20. Therefore, it is possible to prevent the deposits attached to the inner wall surface of the processing container 20 from being peeled off, thereby preventing the deposits from being attached to the main surface 3 of the substrate 2.

[0088] Figure 7 It is a figure which shows the contamination state of the substrate after cleaning which concerns on Example. Figure 8 2 is a diagram showing the contamination status of a substrate after cleaning according to a conventional example. Figure 7 and Figure 8 In the figure, the black dots indicate the locations of the defects.

[0089] exist Figure 7 In the embodiment shown, from time t0 to time t1, the supply pressure P of the mixed gas supplied to the nozzle 40 is 0.9 MPa, the flow ratio of the cluster forming gas to the carrier gas is 25:75, the temperature of the nozzle 40 is -40°C, the gas pressure inside the processing container 20 is, for example, 100 Pa, and the distance between the nozzle 40 and the substrate 2 is 60 mm. The cluster forming gas is CO2 gas, and the carrier gas is H2 gas. In addition, the set time Δt is 30 seconds.

[0090] In addition, Figure 7 In the embodiment shown, from time t1 to time t2, no Figure 6 The flow rate of the carrier gas shown in FIG. 1 is increased, the heater 80 is heated, and the refrigerant is stopped. That is, Figure 7 In the illustrated embodiment, from time t0 to time t2 , the flow rate of the carrier gas is fixed, the heater 80 does not heat the nozzle 40 , and the refrigerant supplier 81 continues to supply refrigerant to the nozzle 40 .

[0091] exist Figure 8 In the conventional example shown in FIG. 1 , except that the supply of the carrier gas is terminated at the same time as the supply of the cluster forming gas is terminated, Figure 7 The illustrated embodiment also performs cleaning of the substrate.

[0092] As the general Figure 7 and Figure 8 As is clear from the comparison, by continuing to supply the carrier gas to the nozzle 40 for the set time Δt after the supply of the cluster forming gas is finished, it is possible to suppress the occurrence of spot-shaped defects on the main surface 3 of the substrate 2 .

[0093] The above describes the embodiments of the substrate cleaning method and substrate cleaning device involved in the present disclosure, but the present disclosure is not limited to the above embodiments, etc. Various changes, corrections, substitutions, additions, deletions and combinations can be made within the scope of the claims. These also naturally belong to the technical scope of the present disclosure.

[0094] The substrate 2 in the above embodiment is a silicon wafer, but may also be a silicon carbide substrate, a sapphire substrate, a glass substrate, or the like.

[0095] This application claims the priority of Japanese Patent Application No. 2019-193049 filed with the Japan Patent Office on October 23, 2019, and the entire contents of Japanese Patent Application No. 2019-193049 are incorporated herein by reference.

[0096] Description of Reference Numerals

[0097] 2: substrate; 3: main surface; 4: cluster; 5: particle; 10: substrate cleaning device; 20: processing container; 30: substrate holding part; 40: nozzle; 50: driving part; 60: gas supply part; 80: heater; 81: refrigerant supply part; 90: control part; 95: gas supply control part; 96: heater control part; 97: refrigerant supply control part; 98: relative position control part.

Claims

1. A substrate cleaning method, comprising the following steps: supplying a mixed gas of a cluster forming gas that forms clusters by adiabatic expansion and a carrier gas having a smaller molecular weight or atomic weight than the cluster forming gas to a nozzle; forming the clusters by ejecting the mixed gas from the nozzle; removing particles attached to the substrate by using the clusters; and From the time when the supply of the cluster forming gas to the nozzle ends, the supply of the carrier gas to the nozzle continues for a set time, in, The set time is predetermined so that the cluster forming gas does not liquefy inside the nozzle.

2. The substrate cleaning method according to claim 1, characterized in that: The step of supplying the mixed gas to the nozzle includes supplying the carrier gas to the nozzle at a first flow rate, The substrate cleaning method includes the step of supplying the carrier gas to the nozzle at a second flow rate greater than the first flow rate during the set time.

3. The substrate cleaning method according to claim 1 or 2, characterized in that: The step of supplying the mixed gas to the nozzle includes a step of prohibiting heating the nozzle by a heater, The substrate cleaning method includes a step of heating the nozzle by a heater during the set time.

4. The substrate cleaning method according to claim 1 or 2, characterized in that: The step of supplying the mixed gas to the nozzle includes the step of supplying a refrigerant to the nozzle. The substrate cleaning method includes the step of prohibiting the supply of the refrigerant to the nozzle during the set time.

5. The substrate cleaning method according to claim 1 or 2, characterized in that: The method further includes the step of setting the relative position of the nozzle and the substrate to a position where the gas is sprayed from the nozzle toward the substrate for the set time.

6. The substrate cleaning method according to claim 1 or 2, characterized in that: The cluster forming gas includes one or more gases selected from carbon dioxide gas and argon gas, The carrier gas includes one or more gases selected from hydrogen and helium.

7. A substrate cleaning device comprising: a substrate holding portion that holds a substrate; a nozzle that sprays a gas toward the substrate held by the substrate holding portion; a gas supply unit that supplies a cluster forming gas that forms clusters by being ejected from the nozzle and adiabatically expanded, and a carrier gas having a smaller molecular weight or atomic weight than the cluster forming gas to the nozzle; and a gas supply control unit that controls the gas supply unit, in, The gas supply control unit supplies a mixed gas of the cluster forming gas and the carrier gas to the nozzle, and continues to supply the carrier gas to the nozzle for a set time after the supply of the cluster forming gas to the nozzle ends. The set time is predetermined so that the cluster forming gas does not liquefy inside the nozzle.

8. The substrate cleaning device according to claim 7, characterized in that: In the step of supplying the mixed gas to the nozzle, the gas supply control unit supplies the carrier gas to the nozzle at a first flow rate. During the set time, the gas supply control unit supplies the carrier gas to the nozzle at a second flow rate greater than the first flow rate.

9. The substrate cleaning device according to claim 7 or 8, characterized in that: have: a heater that heats the nozzle; and a heater control unit that controls the heater, In the step of supplying the mixed gas to the nozzle, the heater control unit prohibits heating the nozzle by the heater, and during the set time, the heater control unit heats the nozzle by the heater.

10. The substrate cleaning device according to claim 7 or 8, characterized in that: have: a refrigerant supply unit configured to adjust a temperature of the nozzle by supplying refrigerant to the nozzle; and a refrigerant supply control unit, which controls the refrigerant supply unit, In the step of supplying the mixed gas to the nozzle, the refrigerant supply control unit supplies the refrigerant to the nozzle, and during the set time, the refrigerant supply control unit prohibits supplying the refrigerant to the nozzle.

11. The substrate cleaning device according to claim 7 or 8, characterized in that: have: a driving unit that moves the nozzle and the substrate holding unit relatively; and a relative position control unit, which controls the driving unit, The relative position control unit makes the relative position of the nozzle and the substrate holding unit be at a position where the gas is sprayed from the nozzle toward the substrate held by the substrate holding unit for the set time.

12. The substrate cleaning device according to claim 7 or 8, characterized in that: The cluster forming gas includes one or more gases selected from carbon dioxide gas and argon gas, The carrier gas includes one or more gases selected from hydrogen and helium. 13 . A computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the substrate cleaning method according to claim 1 is implemented.

Images