Liquid treatment apparatus and cleaning method

Abstract

To prevent remaining of a coating liquid adhering to an inner cup after cleaning the inner cup of a liquid processing apparatus.SOLUTION: A liquid processing apparatus for applying a coating liquid onto a substrate, comprises: a holding part configured to hold and rotate the substrate; a coating liquid supplying part configured to supply the coating liquid to the substrate; and an inner cup configured to surround the holding part from a side, the inner cup having an upper surface on a peripheral edge side inclined downward and outward in a radial direction from a top part located below a peripheral edge side of the held substrate. The inner cup has a plurality of discharge holes formed in the top part along the peripheral direction, and the cleaning liquid discharged from the discharge holes flows down along the upper surface on the peripheral edge side of the inner cup to clean the upper surface on the peripheral edge side. Each discharge hole is formed to discharge the cleaning liquid radially outward and obliquely upward, and the inner cup further includes a storage chamber which is provided in an annular shape along the peripheral direction inside the inner cup, communicates with each of the discharge holes, and stores the cleaning liquid, and an introduction hole which is connected to the storage chamber and introduces the cleaning liquid into the storage chamber.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a liquid processing apparatus and a cleaning method. [Background Art]

[0002] Patent Document 1 discloses an apparatus that performs spin coating, in which various coating liquids such as resist are supplied onto the surface of a semiconductor wafer (hereinafter referred to as "wafer"), and the wafer is rotated to apply the coating liquid over the entire surface of the wafer.

[0003] Patent Document 2 discloses a coating processing apparatus including: a spin chuck that sucks and holds a wafer; a shaft to which the spin chuck is attached; a cup base provided so as to surround the shaft; and a guide ring with a chevron-shaped cross-section provided on the outer peripheral portion of the cup base. This coating processing apparatus is further provided with a cup so as to surround the wafer W held by the spin chuck and the guide ring. The cup can catch and recover liquid splashed or dropped from the wafer. Patent Document 2 also discloses that a rinsing liquid is supplied into the cup from a rinsing liquid discharge port formed at the upper end of the guide ring to clean the inside of the cup. [Prior Art Literature] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Laid-Open No.2019-46833 [Patent Document 2] Japanese Patent Laid-Open No.2012-33886 [Summary of Invention] [Problem to be Solved by the Invention]

[0005] The technology according to the present disclosure prevents coating liquid adhered to the inner cup from remaining after cleaning the inner cup of a liquid processing apparatus. [Means for Solving the Problem]

[0006] One aspect of the present disclosure is a liquid processing apparatus for applying a coating liquid to a substrate, comprising: a holding unit for holding and rotating the substrate; a coating liquid supply unit for supplying a coating liquid to the substrate held by the holding unit; and an inner cup surrounding the holding unit from the side, the inner cup having a plurality of discharge holes formed along the circumferential direction at its top, and the cleaning liquid discharged from the discharge holes is supplied to the The cleaning solution is washed by allowing it to flow down along the upper peripheral surface of the inner cup to which the coating solution has adhered. The discharge holes are formed to discharge the cleaning solution radially outward and diagonally upward. The inner cup is further provided with a storage chamber that is annularly arranged inside the inner cup along the circumferential direction and communicates with each of the discharge holes, storing the cleaning solution, and an introduction hole that is connected to the storage chamber and introduces the cleaning solution into the storage chamber. The radial angle of the discharge port is 0° or greater and parallel to the radial direction. [Effects of the Invention]

[0007] According to this disclosure, after cleaning the inner cup of the liquid processing device, no coating liquid that was adhering to the inner cup remains. [Brief explanation of the drawing]

[0008] [Figure 1] This is a longitudinal cross-sectional view schematically showing the configuration of a resist coating apparatus as a liquid processing apparatus according to the first embodiment. [Figure 2] This is a schematic cross-sectional view showing the configuration of a resist coating apparatus as a liquid processing apparatus according to the first embodiment. [Figure 3] This is a plan view showing the general structure of the cup. [Figure 4] This is a magnified section showing an overview of the cup's structure. [Figure 5] This diagram illustrates an example of the direction of discharge of cleaning fluid from the discharge port in a plan view. [Figure 6]It is a diagram for explaining the reason why the discharge direction of the cleaning liquid from the discharge hole is set to obliquely upward. [Figure 7] It is a diagram for explaining the reason why the discharge direction of the cleaning liquid from the discharge hole is set to obliquely upward. [Figure 8] It is a vertical cross-sectional view schematically showing the configuration of a resist coating apparatus as a liquid processing apparatus according to a second embodiment. [Figure 9] It is a timing chart for explaining an example of supplying cleaning liquid and nitrogen gas. [Figure 10] It is a timing chart for explaining an example of supplying cleaning liquid and nitrogen gas. [Figure 11] It is a timing chart for explaining an example of supplying cleaning liquid and nitrogen gas. [Figure 12] It is a timing chart for explaining an example of supplying cleaning liquid and nitrogen gas. [Figure 13] It is a timing chart for explaining an example of supplying cleaning liquid and nitrogen gas. [Figure 14] It is a timing chart for explaining an example of supplying cleaning liquid and nitrogen gas. [Figure 15] It is a partially enlarged cross-sectional view explaining another example of the discharge hole. [Figure 16] It is a partial cross-sectional view showing an outline of the configuration of another example of an inner cup. [Figure 17] It is a partial cross-sectional view showing an outline of the configuration of another example of an inner cup. [Figure 18] It is a diagram showing an outline of a communication hole. [Figure 19] It is a diagram showing another example of a communication hole. [Figure 20] It is a partial cross-sectional view showing an outline of the configuration of another example of an inner cup. [Figure 21] It is a partial cross-sectional view showing an outline of the configuration of another example of an inner cup. DETAILED DESCRIPTION OF THE INVENTION

[0009] For example, in a photolithography step in a semiconductor device manufacturing process, a coating process is performed in which a coating liquid is applied onto a substrate such as a wafer to form a coating film.

[0010] So-called spin coating, in which a coating liquid is supplied from a nozzle to a rotating substrate and spread over the entire substrate by centrifugal force, is widely used in the above-mentioned coating process (see Patent Documents 1 and 2).

[0011] Some liquid processing apparatuses for performing spin coating include the following substrate holding portion, outer cup, and inner cup. The substrate holding portion holds and rotates the substrate, and the outer cup surrounds the periphery of the substrate held by the substrate holding portion. The inner cup is provided inside the outer cup and surrounds the substrate holding portion from the side, and the upper surface on the peripheral side thereof is an inclined surface that slopes downward toward the outside in the radial direction. In this liquid processing apparatus, the coating liquid scattered or dropped from the substrate is received and recovered by the outer cup, or after being received by the inner cup, flows along the inclined surface on the upper surface of the peripheral side of the inner cup, falls into the outer cup, and is recovered.

[0012] If the coating liquid remains uncollected and adheres to the outer cup or the inner cup, it causes particles and other problems, so it is necessary to wash and remove the coating liquid. As disclosed in Patent Document 2, the inside of the outer cup is cleaned by supplying a cleaning liquid into the outer cup from a discharge hole formed at the upper end of the inner cup. It is also considered that the upper surface on the peripheral side of the inner cup can be cleaned by supplying the cleaning liquid from the discharge hole.

[0013] Incidentally, in recent years, there has been a need to form a thick coating film on a substrate using a coating liquid such as a high-viscosity resist liquid. When the coating liquid is high viscosity, compared to when it is low viscosity, a larger amount of the coating liquid that falls from the substrate remains on the upper peripheral surface of the inner cup. Furthermore, according to the inventors' diligent investigation, when the coating liquid is high viscosity, even if cleaning is performed by supplying cleaning liquid from the discharge hole formed at the upper end of the guide ring, as disclosed in Patent Document 2, some of the coating liquid that was adhering to the upper peripheral surface of the inner cup may remain even after cleaning.

[0014] Therefore, the technology disclosed herein appropriately removes the coating liquid adhering to the inner cup by washing.

[0015] The liquid processing apparatus and cleaning method according to this embodiment will be described below with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant explanations will be omitted.

[0016] (First Embodiment) Figures 1 and 2 are schematic cross-sectional and transverse views, respectively, showing the configuration of a resist coating apparatus as a liquid processing apparatus according to the first embodiment. As shown in Figures 1 and 2, the resist coating apparatus 1 has a housing 10 that can be sealed inside. A wafer W loading / unloading port (not shown) is formed on the side of the housing 10.

[0017] A spin chuck 20 is provided inside the housing 10 as a holding part for holding and rotating the wafer W. The spin chuck 20 can be rotated at a predetermined speed by a chuck drive unit 21 having an actuator such as a motor. The chuck drive unit 21 is also provided with a lifting drive mechanism having an actuator such as a cylinder, allowing the spin chuck 20 to move up and down.

[0018] Furthermore, the housing 10 is provided with a cup 30 that houses the spin chuck 20 and exhausts the liquid from the bottom. This cup 30 receives the coating liquid that is shaken off or falls from the wafer W held by the spin chuck 20 and guides it to be discharged outside the resist coating apparatus 1. Details of this cup 30 will be described later.

[0019] As shown in Figure 2, a rail 40 is formed on the negative X-direction side (downward direction in Figure 2) of the cup 30, extending along the Y-direction (left-right direction in Figure 2). The rail 40 is formed, for example, from the outer side of the cup 30 in the negative Y-direction (leftward direction in Figure 2) to the outer side in the positive Y-direction (rightward direction in Figure 2). An arm 41 is provided on the rail 40.

[0020] An arm 41 supports a discharge nozzle 42, which serves as a coating liquid supply unit. The discharge nozzle 42 discharges a resist liquid as a coating liquid and supplies it to the wafer W held in the spin chuck 20. The viscosity of the resist liquid supplied by the discharge nozzle 42 is, for example, 50 cp to 10000 cP. The arm 41 is movable on the rail 40 by a nozzle drive unit 43, which has an actuator such as a motor. This allows the discharge nozzle 42 to move from a standby unit 44 located outside the cup 30 on the positive Y-direction side to above the center of the wafer W inside the cup 30. Furthermore, the arm 41 can be raised and lowered by the nozzle drive unit 43, allowing the height of the discharge nozzle 42 to be adjusted.

[0021] A supply pipe 51 is connected to the discharge nozzle 42, which communicates with a supply source 50 that stores the resist liquid. The supply pipe 51 is equipped with a group of supply devices 52, including a valve that controls the flow of the resist liquid and a flow rate adjustment unit that adjusts the flow rate of the resist liquid.

[0022] Furthermore, in the resist coating apparatus 1, a supply pipe 61 is connected to the cup 30, which communicates with a supply source 60 that stores a cleaning solution for cleaning the cup 30. Specifically, the supply pipe 61 is connected to the inlet hole of the inner cup of the cup 30, which will be described later. The supply pipe 61 is equipped with a group of supply devices 62, including a valve for controlling the flow of the cleaning solution and a flow rate adjustment unit for adjusting the flow rate of the cleaning solution.

[0023] Furthermore, the resist coating apparatus 1 is provided with a control unit U. The control unit U is, for example, a computer equipped with a CPU and memory, and has a program storage unit (not shown). The program storage unit also stores a program for controlling the nozzle drive unit 43, the supply equipment group 52, the supply equipment group 62, etc., to realize the resist film formation process and cleaning process described later. The above-mentioned program may have been recorded on a storage medium readable by the computer and installed from that storage medium to the control unit U. Part or all of the program may be implemented on dedicated hardware (circuit board).

[0024] Next, referring to Figure 1, the cup 30 will be described using Figures 3 to 7. Figures 3 and 4 are a plan view and a partially enlarged view showing the general configuration of the cup 30. Figure 5 is a diagram illustrating an example of the direction in which the discharge hole, described later, discharges the cleaning liquid in a plan view. Figures 6 and 7 are diagrams illustrating the reason why the direction in which the cleaning liquid is discharged from the discharge hole, described later, is diagonally upward.

[0025] As shown in Figure 1, the cup 30 has an outer cup 100 that surrounds the periphery of the wafer W held by the spin chuck 20, and an inner cup 110 that is located inside the outer cup 100 and below the wafer W held by the spin chuck 20, and surrounds the shaft portion 20a of the spin chuck 20 from the side.

[0026] The outer cup 100 has a cylindrical outer circumferential wall 101, an inclined wall 102 that extends diagonally inward and upward around the entire circumference from the upper end of the outer circumferential wall 101, and a bottom wall 103 that is annular in plan view and extends horizontally inward around the entire circumference from the lower end of the outer circumferential wall 101. Furthermore, the outer cup 100 has a cylindrical inner circumferential wall 104 that extends vertically upward from the inner circumferential end of the bottom wall 103, and a cylindrical intermediate wall 105 that extends vertically upward from between the outer circumferential wall 101 and the inner circumferential wall 104 in the bottom wall 103.

[0027] A drain port 106 for discharging the liquid collected by the cup 30 is formed between the outer peripheral wall 101 and the intermediate wall 105 of the bottom wall 103, and a drain pipe 107 is connected to this drain port 106. Furthermore, an exhaust port 108 is formed between the intermediate wall 105 and the inner peripheral wall 104 in the bottom wall 103 to exhaust the atmosphere around the wafer W, and an exhaust pipe 109 is connected to this exhaust port 108.

[0028] The inner cup 110 has a guide portion 111 that is formed in a mountain shape in cross-section and an annular shape in plan view, extending around its entire circumference. The upper surface 112 on the peripheral side of the guide portion 111 is an inclined surface that slopes downward radially outward from the top portion 113 located below the peripheral edge of the wafer W held by the spin chuck 20. Hereinafter, the upper surface 112 on the peripheral side may be referred to as the inclined surface 112. Note that "radial direction" refers to the radial direction around the central axis of the cup 30, which coincides with the rotation axis of the spin chuck 20, the central axis of the outer cup 100, and the central axis of the inner cup 110, and the same applies in the following description. The inner cup 110 is supported within the outer cup 100 by the guide portion 111 being supported by the inner peripheral wall 104 of the outer cup 100. Furthermore, the inner cup 110 has a cylindrical vertical wall 114 that extends vertically downward from the outer peripheral end of the guide portion 111. The vertical wall 114 is located between the outer peripheral wall 101 and the intermediate wall 105 of the outer cup 100.

[0029] A gap forming an exhaust path d is created between the vertical wall 114 and the outer peripheral wall 101 of the outer cup 100. Furthermore, a bent passage is formed by the vertical wall 114, the bottom wall 103, the intermediate wall 105, the guide section 111, and the inner peripheral wall 104. This bent passage constitutes the gas-liquid separation section.

[0030] In cup 30, the coating liquid that is scattered or falls from the wafer W is received and collected in the outer cup 100, or it is received by the inclined surface 112 of the inner cup 110, flows along the inclined surface 112, falls into the outer cup 100 and is collected.

[0031] Furthermore, as shown in Figures 3 and 4, the inner cup 110 has a discharge hole 120 for discharging the cleaning solution. As the cleaning solution, for example, thinner, which is a solvent for resist solutions, can be used.

[0032] Multiple discharge holes 120 are formed along the circumferential direction on the top 113 of the inner cup 110. Specifically, the discharge holes 120 are formed at predetermined intervals along the circumferential direction such that their tips are located above the inclined surface 112. The term "circumferential direction" refers to the circumferential direction around the central axis of the cup 30, which coincides with the rotation axis of the spin chuck 20, the central axis of the outer cup 100, and the central axis of the inner cup 110, and the same applies to the following explanation.

[0033] The total number of discharge holes 120 is, for example, 100 to 300. Each discharge hole 120 is located outside the outer edge of the spin chuck 20 in a plan view. Furthermore, the flow paths constituting each discharge port 120 are, for example, cylindrical in shape. Furthermore, the diameter of the flow path constituting the discharge port 120 is, for example, common to all discharge ports 120.

[0034] Furthermore, a storage chamber 121 communicating with each discharge hole 120 is provided inside the guide portion 111 of the inner cup 110. The storage chamber 121 is provided as a single annular chamber along the circumferential direction. The storage chamber 121 may be divided into multiple chambers (for example, 2 to 5) along the circumferential direction, as long as the number of chambers is less than the total number of discharge holes 120.

[0035] Furthermore, the inner cup 110 is connected to an inlet 122 that is connected to a storage chamber 121 and introduces cleaning fluid into the storage chamber 121. A cleaning fluid supply pipe 61 (see Figure 1) is connected to the inlet 122. In the example in Figure 3, one inlet 122 is provided for each storage chamber 121. The number of inlet 122s for one storage chamber 121 may be multiple (for example, 2 to 5) as long as it is less than the total number of discharge holes 120.

[0036] The cleaning liquid supplied to the storage chamber 121 via the supply pipe 61 and the inlet hole 122 is discharged from each discharge hole 120. The cleaning liquid discharged from each discharge hole 120 flows down along the inclined surface 112 of the inner cup 110 to which the resist liquid has adhered. This removes the resist adhering to the inclined surface 112. In other words, the inclined surface 112 is cleaned.

[0037] In a plan view, the discharge direction Dt of the cleaning liquid from each discharge hole 120 is radially outward through the discharge hole 120. The discharge direction Dt may be parallel to the radial direction Dr, or, as shown in Figure 5, it may be a direction having an angle α (α>0°) with respect to the radial direction Dr. By setting the discharge direction to a direction having an angle α with respect to the radial direction Dr, the cleaning liquid can be supplied more uniformly to the outer peripheral edge of the inclined surface 112 of the inner cup 110 in the circumferential direction of the cup 30. Therefore, the possibility of resist liquid remaining attached to the inclined surface 112 of the inner cup 110 can be further reduced.

[0038] Furthermore, as shown in Figure 4, the discharge direction Ds of the cleaning fluid from each discharge hole 120 in a side view is diagonally upward. In other words, the discharge direction Ds is a direction having an angle β (β>0°) with respect to the horizontal direction Dh.

[0039] According to the inventor's diligent investigation, when the discharge direction Ds is horizontal, after a predetermined amount of cleaning liquid is discharged from the discharge hole 120 and used for cleaning, the resist liquid sometimes remains on the outer edge of the inclined surface 112 of the inner cup 110 in a striped pattern along the radial direction. This is thought to be because, when the discharge direction Ds is horizontal, the cleaning liquid discharged from the discharge hole 120 comes into contact with the inclined surface 112 immediately after discharge and is susceptible to the influence of the surface energy of the inclined surface 112.

[0040] Unlike the above, if the cleaning liquid discharged from the discharge hole 120 does not immediately contact the inclined surface 112 after discharge and is away from the inclined surface, it will spread circumferentially in the space above the inclined surface 112, then collide with the inclined surface 112, and then flow radially. In this case, as shown in Figure 6, the region R1 on the inclined surface 112 to which the cleaning liquid is supplied from each discharge hole 120 is wide on the outer edge side of the inclined surface 112. In contrast, if the discharged liquid discharged from the discharge hole 120 immediately contacts the inclined surface 112 after discharge, it does not spread circumferentially around the cup 30, but flows along the radial direction of the cup 30 on the inclined surface 112. In this case, as shown in Figure 7, the region R2 on the inclined surface 112 to which the cleaning liquid is supplied from each discharge hole 120 is narrow on the outer edge side of the inclined surface 112. Therefore, it is thought that areas with insufficient supply of cleaning liquid occur in a striped pattern along the radial direction on the outer edge side of the inclined surface 112, resulting in the resist liquid remaining in a striped pattern.

[0041] Therefore, in this embodiment, the discharge direction Ds is set to be diagonally upward.

[0042] Next, an example of the resist coating process in the resist coating apparatus 1 will be described. The following series of processes are performed under the control of the control unit U.

[0043] In the resist coating process, first, the wafer W is held by adsorption on the upper surface of the spin chuck 20. Then, the discharge nozzle 42 is moved to the upper center of the wafer W. Next, the wafer W is rotated at a low speed (e.g., 100 rpm), and during this rotation, resist liquid is supplied onto the wafer W from the discharge nozzle 42.

[0044] Then, when the amount of resist liquid supplied from the discharge nozzle 42 reaches a predetermined amount, the supply of resist liquid is stopped, and the discharge nozzle 42 is retracted. After that, the wafer W is rotated at a higher rotational speed (e.g., 3000 rpm), and the resist liquid supplied to the center of the wafer W is diffused over the entire surface of the wafer W to form a coating film of a predetermined thickness. Next, the wafer W is rotated at a predetermined rotational speed (e.g., 1000 rpm) to dry the coating film on the wafer W.

[0045] Subsequently, the wafer W, which was held by adsorption on the spin chuck 20, is removed from the resist coating apparatus 1. This completes the series of processes involved in the resist coating process.

[0046] Next, an example of the cleaning process in the resist coating apparatus 1 will be described. The following cleaning process is performed under the control of the control unit U. The cleaning process is performed, for example, in parallel with the resist coating process. Furthermore, the cleaning process may be performed each time the number of wafers W that have undergone resist coating (i.e., the number of processed wafers) exceeds a certain number, or after a certain amount of time has elapsed, or it may be performed during maintenance.

[0047] During the cleaning process, the supply of cleaning solution to the storage chamber 121 is initiated, and the discharge of cleaning solution from all discharge holes 120 begins. The discharge flow rate of the cleaning solution from the discharge holes 120 at this time is, for example, 100 ml / min to 1000 ml / min. As described above, the cleaning solution discharged from each discharge hole 120 spreads circumferentially in the space above the inclined surface 112, then collides with the peripheral edge of the inclined surface 112, and then flows radially along the inclined surface 112. As a result, the cleaning solution is supplied to the entire peripheral edge of the inclined surface 112, and all of the resist solution adhering to the peripheral edge of the inclined surface 112 is removed.

[0048] When the discharge time of the cleaning solution from the discharge port 120 reaches a predetermined time (for example, 5 seconds to 300 seconds), the supply of the cleaning solution to the storage chamber 121 is stopped, and the cleaning process is completed.

[0049] As described above, in this embodiment, multiple discharge holes 120 for discharging cleaning liquid radially outward are provided on the top 113 of the inner cup 110 along the circumferential direction. The direction of discharge of the cleaning liquid from each discharge hole 120 is diagonally upward. Therefore, the cleaning liquid discharged from each discharge hole 120 flies away from the inclined surface 112 of the inner cup 110 and is not affected by the surface energy of the inclined surface 112. Consequently, the cleaning liquid discharged from the discharge holes 120 spreads circumferentially in the space above the inclined surface 112 and then flows over the inclined surface 112. Thus, the cleaning liquid can be supplied to the entire outer peripheral edge region, which is the region on the inclined surface 112 where the resist liquid mainly adheres, and the resist liquid can be completely removed from the inclined surface 112. In other words, according to this embodiment, the coating liquid adhering to the inclined surface 112 of the inner cup 110 can be appropriately removed by cleaning.

[0050] (Second Embodiment) Figure 8 is a schematic longitudinal cross-sectional view showing the configuration of a resist coating apparatus as a liquid processing apparatus according to the second embodiment. In the resist coating apparatus 1a shown in Figure 8, a supply pipe 201, which communicates with a supply source 200 that stores nitrogen (N2) gas as an inert gas, is connected to the supply pipe 61. In other words, nitrogen gas, as well as the cleaning solution, is introduced into the storage chamber 121 (see Figure 3, etc.) through the inlet 122 (see Figure 3, etc.) to which the supply pipe 61 is connected.

[0051] The supply pipe 201 is equipped with a group of supply equipment 202, which includes valves for controlling the flow of nitrogen gas and a flow rate control unit for adjusting the flow rate of nitrogen gas. The group of supply equipment 202 is controlled by a control unit U.

[0052] Figures 9 to 14 are timing charts illustrating examples of cleaning solution and nitrogen gas supply.

[0053] (Example 1 of supplying cleaning solution and nitrogen gas) For example, under the control of the control unit U, the supply of cleaning fluid to the storage chamber 121 and the supply of nitrogen gas to the storage chamber 121 are performed simultaneously, as shown in Figure 9. At that time, under the control of the control unit U, both the flow rate of the cleaning fluid supplied to the storage chamber 121 and the flow rate of the nitrogen gas supplied to the storage chamber 121 are kept constant. In this way, by supplying nitrogen gas along with the cleaning liquid to the storage chamber 121 simultaneously, the cleaning liquid can be discharged from the discharge holes 120 (see Figure 3, etc.) at a higher flow rate. The cleaning liquid discharged from the discharge holes 120 spreads more in the circumferential direction the longer it travels in the space above the inclined surface 112, before colliding with the inclined surface 112 of the inner cup 110. As mentioned above, if the flow rate of the cleaning liquid discharged from the discharge holes 120 is high, it travels further in the space above the inclined surface 112. Therefore, by supplying nitrogen gas along with the cleaning liquid to the storage chamber 121, the cleaning liquid can be supplied from each discharge hole 120 to a wider area in the circumferential direction on the outer edge of the inclined surface 112.

[0054] (Example 2 of supplying cleaning solution and nitrogen gas) In this example, similar to supply example 1, the supply of cleaning solution to the storage chamber 121 and the supply of nitrogen gas to the storage chamber 121 are performed simultaneously, and the flow rate of nitrogen gas supplied to the storage chamber 121 is constant. However, in this example, the flow rate of cleaning solution supplied to the storage chamber 121 is switched alternately between a high flow rate and a low flow rate, as shown in Figure 10. Specifically, it is as follows.

[0055] In supply examples 1 and 2, when the cleaning solution and nitrogen gas are supplied simultaneously, even if the supply flow rate of the cleaning solution is constant, a peak in the flow velocity of the cleaning solution discharged from the discharge port 120 occurs at a predetermined interval (each time the amount of cleaning solution in the storage chamber 121 is at its maximum). In this example, the supply flow rate of the cleaning solution to the storage chamber 121 is switched to a high flow rate at the timing when the flow velocity of the cleaning solution discharged from the discharge port 120 peaks, i.e., when the cleaning solution is discharged from the discharge port 120. Subsequently, the supply flow rate of the cleaning solution to the storage chamber 121 is switched to a low flow rate when the discharge of the cleaning solution from the discharge port 120 is interrupted or when the flow rate falls below a predetermined level.

[0056] In supply examples 1 and 2, when the cleaning solution and nitrogen gas are supplied simultaneously, flow interference occurs between the supply flow rate of the cleaning solution and the supply flow rate of the nitrogen gas. This can reduce the peak flow velocity of the cleaning solution discharged from the discharge port 120, and consequently, the flow rate of the cleaning solution discharged from the discharge port 120 at that peak. In contrast, in cleaning example 2, the supply flow rate of the cleaning solution to the storage chamber 121 becomes high at the timing when the peak flow velocity of the cleaning solution discharged from the discharge port 120 occurs. Therefore, a decrease in the flow rate of the cleaning solution discharged from the discharge port 120 at that peak can be prevented.

[0057] (Example 3 of supplying cleaning solution and nitrogen gas) In this example, similar to supply example 1, the supply of cleaning solution to the storage chamber 121 and the supply of nitrogen gas to the storage chamber 121 are performed simultaneously, and the flow rate of the cleaning solution supplied to the storage chamber 121 is constant. However, in this example, the flow rate of the nitrogen gas supplied to the storage chamber 121 is switched alternately between a high flow rate and a low flow rate, as shown in Figure 11. Specifically, it is as follows.

[0058] In this example, the nitrogen gas supply flow rate to the storage chamber 121 is switched to a high flow rate at the moment when the flow velocity of the cleaning liquid discharged from the discharge port 120 peaks, that is, at the moment when the cleaning liquid is discharged from the discharge port 120. Subsequently, the nitrogen gas supply flow rate to the storage chamber 121 is switched to a low flow rate at the moment when the discharge of the cleaning liquid from the discharge port 120 is interrupted, etc.

[0059] In cleaning example 3, the nitrogen gas supply flow rate to the storage chamber 121 becomes high at the timing when the flow velocity of the cleaning liquid discharged from the discharge port 120 peaks. Therefore, it is possible to prevent a decrease in the flow rate of the cleaning liquid discharged from the discharge port 120 at the aforementioned peak.

[0060] (Example 4 of supplying cleaning solution and nitrogen gas) In this supply example, under the control of the control unit U, the supply of cleaning fluid to the storage chamber 121 and the supply of nitrogen gas to the storage chamber 121 are performed alternately, as shown in Figure 12. At that time, under the control of the control unit U, the supply pressure of nitrogen gas is set higher than that of the cleaning fluid. Simultaneously, under the control of the control unit U, both the supply flow rate of cleaning fluid to the storage chamber 121 and the supply flow rate of nitrogen gas to the storage chamber 121 are kept constant.

[0061] As in this example, by alternately supplying cleaning solution to the storage chamber 121 and supplying nitrogen gas to the storage chamber 121, and by keeping the nitrogen gas supply pressure high, the cleaning solution can be discharged from the discharge port 120 at a higher flow rate. Furthermore, by performing the process alternately as in this example, the aforementioned flow interference does not occur, so the cleaning solution can be discharged from the discharge port 120 efficiently and at a large flow rate.

[0062] (Example 5 of supplying cleaning solution and nitrogen gas) In this example, similar to supply example 4, the supply of cleaning liquid to the storage chamber 121 and the supply of nitrogen gas to the storage chamber 121 are performed alternately, and the flow rate of nitrogen gas supplied to the storage chamber 121 is constant. However, in this example, the flow rate of cleaning liquid supplied to the storage chamber 121 changes as shown in Figure 13. Specifically, the flow rate of the cleaning liquid is set to a low flow rate for a predetermined time after switching from nitrogen gas supply to cleaning liquid supply, and then gradually increased. This prevents the cleaning liquid from flowing back into the supply pipe 201 leading to the nitrogen gas supply source 200. Furthermore, the flow rate of the cleaning liquid is set to a high flow rate in the latter half of the cleaning liquid supply stage. This eliminates air bubbles in the storage chamber 121 of the inner cup 110.

[0063] (Example 6 of supplying cleaning solution and nitrogen gas) In this example, similar to supply example 4, the supply of cleaning solution to the storage chamber 121 and the supply of nitrogen gas to the storage chamber 121 are performed alternately, and the flow rate of the cleaning solution supplied to the storage chamber 121 is constant. However, in this example, the flow rate of the nitrogen gas supplied to the storage chamber 121 changes as shown in Figure 14. Specifically, the flow rate of the nitrogen gas supplied is set to a high flow rate in the first half of the nitrogen gas supply stage and to a low flow rate in the second half.

[0064] When the supply of cleaning solution and nitrogen gas are performed alternately, as in supply examples 4 to 6, a liquid film of the cleaning solution may form at the opening of the tip of the discharge hole 120 at the end of the nitrogen gas supply stage. If nitrogen gas is supplied while a liquid film of cleaning solution has formed, droplets of cleaning solution will be released from the discharge hole 120 and float inside the housing 10. These floating droplets of cleaning solution may adversely affect the resist solution coating film on the wafer W, for example, when the cleaning process and the resist coating process are performed in parallel.

[0065] In contrast, in this example, as described above, the nitrogen gas supply flow rate is reduced in the latter half of the nitrogen gas supply stage. Therefore, even if a liquid film of the cleaning solution forms at the opening of the tip of the discharge hole 120 at the end of the nitrogen gas supply stage, and splashes of the cleaning solution are generated, the resulting splashes of the cleaning solution will have a larger particle size. Consequently, the splashes of the cleaning solution will not float inside the housing 10 for a long time. As a result, the possibility that splashes of the cleaning solution scattered from the discharge hole 120 will affect the resist solution coating film on the wafer W can be reduced.

[0066] Furthermore, as in this example, setting the nitrogen gas supply flow rate to a high rate in the first half of the nitrogen gas supply stage means setting the nitrogen gas supply flow rate to a high rate in the first half of the cleaning liquid discharge stage from the discharge port 120. In addition, the cleaning liquid is discharged at a high flow rate in the first half of the cleaning liquid discharge stage from the discharge port 120. By setting the nitrogen gas supply flow rate to a high rate in the first half of the cleaning liquid discharge stage, where the cleaning liquid is discharged at a high flow rate, and increasing the flow velocity of the cleaning liquid discharged from the discharge port 120, a larger volume of cleaning liquid can be supplied to a wider area on the outer edge of the inclined surface 112. In other words, the supply distribution of the cleaning liquid can be further improved.

[0067] (Variations of the inner cup) Figure 15 is a partially enlarged cross-sectional view illustrating another example of a discharge port. In the above example, the flow paths constituting each discharge hole 120 were cylindrical. That is, the flow paths constituting each discharge hole 120 had a uniform diameter from the base to the tip. Alternatively, as shown in Figure 15, the flow paths constituting each discharge hole 120a may be narrower at the tip compared to the base. This allows the cleaning fluid to be discharged from each discharge hole 120a at a higher flow velocity.

[0068] Furthermore, in the above example, the diameter of the flow path constituting the discharge hole 120 was the same among the discharge holes 120. Alternatively, the diameter of the flow path constituting the discharge hole 120 may be varied according to the distance from the discharge hole 120 to the inlet hole 122. Specifically, the diameter of the flow path constituting the discharge hole 120 may be made wider the further the distance from the discharge hole 120 to the inlet hole 122. This makes it possible to increase the flow velocity during discharge even from discharge holes 120 that tend to have lower discharge pressure, i.e., lower flow velocity during discharge, due to the distance to the inlet hole 122. Therefore, the flow velocity of the cleaning liquid discharged from the discharge holes 120 can be made uniform among the discharge holes 120. As a result, the possibility of unevenness in the supply distribution of the cleaning liquid to the inclined surface 112 can be further reduced.

[0069] Furthermore, the upward diagonal discharge angle of the cleaning solution from the discharge hole 120 may be varied depending on the distance from the discharge hole 120 to the inlet hole 122. Specifically, the upward diagonal discharge angle of the cleaning solution from the discharge hole 120 may be increased as the distance from the discharge hole 120 to the inlet hole 122 increases. Discharge holes 120 that are far from the inlet hole 122 tend to have lower discharge pressure, i.e., lower flow velocity during discharge, and the discharged cleaning liquid is more susceptible to the surface energy of the inclined surface 112. In contrast, as in this example, by increasing the upward discharge angle of the cleaning liquid to discharge holes 120 that are far from the inlet hole 122, the cleaning liquid discharged from these discharge holes 120 is less susceptible to the surface energy. Therefore, the area in which each discharge hole 120 supplies cleaning liquid to the outer edge of the inclined surface 112 can be made uniform among the discharge holes 120. As a result, the possibility of unevenness in the supply distribution of cleaning liquid to the inclined surface 112 can be further reduced.

[0070] Figure 16 is a partial cross-sectional view illustrating a schematic configuration of another example of the inner cup. As mentioned above, splashes of cleaning solution may be released from the discharge hole 120. To prevent the diffusion of these splashes of cleaning solution, a shielding plate 300 may be provided on the inclined surface 112. More specifically, the shielding plate 300 is intended to prevent splashes of cleaning solution released from the discharge hole 120 from diffusing inward from the discharge hole 120. The shielding plate 300 is formed, for example, to extend horizontally from a position above the discharge hole 120 on the inclined surface 112. The length of the shielding plate 300 is such that a clump of cleaning solution discharged from the discharge hole 120 under normal conditions does not collide with the tip of the shielding plate 300. Note that "under normal conditions" means a period during which no splashes of cleaning solution are released.

[0071] Figure 17 is a partial cross-sectional view illustrating the configuration of another example of the inner cup. Figure 18 is a schematic diagram of the communication hole, which will be discussed later. As shown in Figure 17, the storage chamber 121a may be divided into two annular buffers 410 and 411 in a plan view along the circumferential direction by a partition wall 400 that divides the interior of the storage chamber 121a into two regions along the fluid flow. In this case, the partition wall 400 has multiple communication holes 401. The communication holes 401 connect the upstream buffer (hereinafter sometimes referred to as the "primary buffer") 410 and the downstream buffer (hereinafter sometimes referred to as the "secondary buffer") 411, which are separated by the partition wall 400.

[0072] The communication holes 401 are formed in the shape of slits that are long in the circumferential direction and short in the radial direction, as shown in Figure 18, for example. Furthermore, the communication holes 401 are provided at predetermined intervals along the entire circumference. The number of communication holes 401 is, for example, the number such that the total length of communication holes 401 in the circumferential direction is 180° or more.

[0073] As described above, by providing two buffers 410 and 411, and by providing communication holes 401 at predetermined intervals along the entire circumference of the partition wall 400 separating these buffers 410 and 411, the following effects are obtained. That is, the cleaning liquid is supplied from the primary buffer 410 to the secondary buffer 411 which communicates with the discharge hole 120 at a uniform pressure in the circumferential direction. Therefore, the cleaning liquid is discharged from the discharge hole 120 at a uniform pressure, i.e., flow velocity, in the circumferential direction. Consequently, the cleaning liquid can be supplied uniformly in the circumferential direction to the outer edge of the inner cup 110a.

[0074] Figure 19 shows another example of a communication hole. The shape of the communication hole 401a may be a frustoconical shape, as shown in Figure 19. In this shape as well, the communication holes 401a are provided at predetermined intervals along the circumferential direction, extending around the entire circumference.

[0075] Figure 20 is a partial cross-sectional view illustrating a schematic configuration of another example of the inner cup. In the example in Figure 18, the storage chamber 121a was divided into two buffers 410 and 411. The storage chamber is not limited to this example and may be divided into three or more buffers. For example, in the inner cup 110b of Figure 20, the storage chamber 121b is divided into three buffers 500 to 502, and these buffers 500 to 502 are stacked horizontally in the figure.

[0076] A partition wall 510 is provided between the upstream buffer 500 and the intermediate buffer 501, and a partition wall 511 is provided between the intermediate buffer 501 and the downstream buffer 502. Furthermore, a communication hole 512 is provided in the partition wall 510 to connect buffer 500 and buffer 501, and a communication hole 513 is provided in the partition wall 511 to connect buffer 501 and buffer 502. Of the communication holes 512 and 513, at least the communication hole 513 is provided at predetermined intervals along the entire circumference of the cup 30, similar to the communication hole 401 in Figure 17. In the following, the communication hole 512 is assumed to be formed in an annular shape in plan view.

[0077] Furthermore, it is preferable that the communication holes 512 and 513 do not lie on the same straight line in their through-directions. This is because, when they are aligned on the same straight line, the cleaning fluid is supplied from the communication hole 513 to the downstream buffer 502 communicating with the discharge hole 120 at a higher pressure compared to when they are not, and as a result, the discharge pressure of the cleaning fluid from the discharge hole 120 becomes more uneven in the circumferential direction of the cup 30.

[0078] Furthermore, it is preferable that the direction in which the cleaning fluid is introduced into the storage chamber 121b through the inlet hole 122 and the direction in which the communication hole 512 provided in the uppermost partition wall 510 penetrates are not aligned on the same line. This is because if they are aligned on the same line, the discharge pressure of the cleaning fluid from the discharge hole 120 closest to the inlet hole 122 may be higher than that from the other discharge holes 120.

[0079] Similarly, when there are two buffers as shown in Figure 17, it is preferable that the direction in which the cleaning liquid is introduced into the storage chamber 121a through the inlet hole 122 and the direction in which the communication hole 401 penetrates are not aligned on the same line. This is because cleaning liquid is supplied to the secondary buffer 411 at a higher pressure from the communication hole 401 that penetrates in a direction aligned with the direction in which the cleaning liquid is introduced through the inlet hole 122 than from the other communication hole 401, and as a result the discharge pressure of the cleaning liquid from the discharge hole 120 becomes uneven in the circumferential direction of the cup 30.

[0080] Figure 21 is a partial cross-sectional view illustrating a schematic configuration of another example of the inner cup. In the inner cup 110c shown in Figure 21, a recessed area 520 is formed at the bottom of the buffer 500, where the nitrogen gas introduced into the storage chamber 121c collides as it travels along the uppermost buffer 500. Therefore, the nitrogen gas introduced into the storage chamber 121c enters the recessed area 520, reducing its flow velocity before being supplied to the buffer 501. Consequently, the high flow velocity of the cleaning liquid supplied to the buffer 501 prevents the discharge pressure of the cleaning liquid from the discharge hole 120 from becoming uneven in the circumferential direction.

[0081] Furthermore, in the inner cup 110c shown in Figure 21, a recess 521 is formed at the lower end of the partition wall 510, which is cut out to be recessed upward. This recess 521 is provided at predetermined intervals along the entire circumference of the cup 30.

[0082] By providing such a recess 521, the nitrogen gas introduced into the storage chamber 121 can only escape through this recess 521. Therefore, the distribution of nitrogen gas can be improved.

[0083] Unlike the above examples, a separate discharge port for an inert gas such as nitrogen gas may be provided above the discharge port for the cleaning solution on the inclined surface 112, thereby assisting the diffusion of the cleaning solution with the inert gas.

[0084] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of Symbols]

[0085] 1. Resist coating apparatus 1a Resist coating apparatus 20 Spin Chuck 42 Discharge nozzles 100 Outer cups 110 inner cup 110a inner cup 110cm inner cup 112 Peripheral side upper surface (slanted surface) 113 Top 120 Discharge hole 120a Discharge hole W wafer

Claims

1. A liquid processing apparatus for applying a coating solution onto a substrate, A holding part that holds and rotates the substrate, A coating liquid supply unit that supplies coating liquid to the substrate held by the holding unit, The retaining portion is surrounded from the side, and its peripheral upper surface is an inner cup that slopes downward radially outward from the top located below the peripheral edge of the substrate held by the retaining portion, The inner cup has a plurality of discharge holes formed along the circumferential direction at its top, The discharge hole is formed to discharge the cleaning liquid radially outward and diagonally upward. The aforementioned inner cup is The inner cup is provided with a storage chamber that is circularly arranged along the circumferential direction, communicates with each of the discharge holes, and stores the cleaning liquid. A liquid processing apparatus further comprising an inlet connected to the storage chamber for introducing a cleaning liquid into the storage chamber.

2. The storage chamber is divided into multiple annular buffers along the circumferential direction by partition walls that divide the interior of the storage chamber into multiple regions along the fluid flow. The liquid processing apparatus according to claim 1, wherein the partition wall is provided with a communication hole that connects the buffers separated by the partition wall.

3. The liquid processing apparatus according to claim 1 or 2, wherein the diameter of the flow path constituting the discharge hole varies depending on the distance from the discharge hole to the inlet hole.

4. The liquid processing apparatus according to any one of claims 1 to 3, wherein an inert gas is also introduced into the storage chamber through the introduction hole.

5. The supply of the cleaning liquid to the storage chamber and the supply of the inert gas to the storage chamber are performed simultaneously. The liquid processing apparatus according to claim 4, wherein the flow rate of the cleaning liquid supplied to the storage chamber and the flow rate of the inert gas supplied to the storage chamber are constant.

6. The supply of the cleaning liquid to the storage chamber and the supply of the inert gas to the storage chamber are performed simultaneously. The liquid processing apparatus according to claim 4, wherein the flow rate of the cleaning liquid supplied to the storage chamber is constant, and the flow rate of the inert gas supplied to the storage chamber is alternately switched between a high flow rate and a low flow rate.

7. The supply of the cleaning liquid to the storage chamber and the supply of the inert gas to the storage chamber are performed alternately. The liquid processing apparatus according to claim 4, wherein the flow rate of the cleaning liquid supplied to the storage chamber and the flow rate of the inert gas supplied to the storage chamber are constant.

8. The supply of the cleaning liquid to the storage chamber and the supply of the inert gas to the storage chamber are performed alternately. The liquid processing apparatus according to claim 4, wherein the flow rate of the inert gas supplied to the storage chamber is constant, and the flow rate of the cleaning liquid supplied to the storage chamber changes.

9. The supply of the cleaning liquid to the storage chamber and the supply of the inert gas to the storage chamber are performed alternately. The liquid processing apparatus according to claim 4, wherein the flow rate of the cleaning liquid supplied to the storage chamber is constant, and the flow rate of the inert gas supplied to the storage chamber changes.

10. The liquid processing apparatus according to claim 2, wherein the direction in which the cleaning liquid is introduced through the introduction hole and the direction in which the communication hole provided in the uppermost partition wall penetrates are not aligned on the same straight line.

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