Substrate processing device and substrate processing method

Abstract

This substrate processing device is provided with a holding unit, a nozzle, an imaging unit, a cooling unit, and a control circuit. The holding unit rotatably holds a substrate. The nozzle discharges a treatment liquid onto the surface of the substrate. The imaging unit images the surface of the substrate. The cooling unit cools the substrate. The control circuit executes liquid treatment, imaging processing, determination processing, and cooling processing. In the liquid treatment, the treatment liquid is discharged from the nozzle toward the surface of the rotating substrate. In the imaging processing, the imaging unit is used to capture an image of the surface of the substrate during the liquid treatment. In the determination processing, it is determined, on the basis of the captured image obtained by the imaging processing, whether or not a reaction due to the treatment liquid is complete, for each of a plurality of positions along the radial direction of the substrate on the surface of the substrate, during the liquid treatment. In the cooling processing, the cooling unit is used to cool the substrate if it is determined that the reaction due to the treatment liquid is complete for at least one of the plurality of positions on the surface of the substrate.

Description

SUBSTRATE PROCESSING APPARATUS AND SUBSTRATE PROCESSING METHOD

[0001] The present disclosure relates to a substrate processing apparatus and a substrate processing method.

[0002] 2. Description of the Related Art Conventionally, there has been known a substrate processing apparatus that processes a substrate such as a semiconductor wafer by rotating the substrate and supplying a processing liquid to the surface of the rotating substrate.

[0003] Japanese Patent Application Laid-Open No. 2022-45616

[0004] The present disclosure provides a technique that can suppress damage to exposed portions on the surface of a substrate during liquid processing.

[0005] A substrate processing apparatus according to one aspect of the present disclosure includes a holding unit, a nozzle, an imaging unit, a cooling unit, and a control circuit. The holding unit rotatably holds a substrate. The nozzle ejects a processing liquid onto the surface of the substrate held by the holding unit. The imaging unit captures an image of the surface of the substrate held by the holding unit. The cooling unit cools the substrate held by the holding unit. The control circuit executes a liquid processing, an imaging process, a determination process, and a cooling process. The liquid processing involves ejecting a processing liquid from the nozzle toward the surface of the rotating substrate. The imaging process involves using the imaging unit to capture an image of the surface of the substrate during the liquid processing. The determination process involves determining, based on the images captured by the imaging process, whether a reaction caused by the processing liquid has ended for each of multiple positions along the radial direction of the substrate on the surface of the substrate during the liquid processing. The cooling process involves cooling the substrate using the cooling unit when it is determined that a reaction caused by the processing liquid has ended for at least one of the multiple positions on the surface of the substrate during the liquid processing.

[0006] According to the present disclosure, damage to exposed portions on the surface of a substrate during liquid processing can be suppressed.

[0007] FIG. 1 is a diagram showing a schematic configuration of a substrate processing system according to an embodiment. FIG. 2 is a schematic diagram showing an example of the configuration of a processing unit according to an embodiment. FIG. 3 is a block diagram showing the configuration of a control device according to an embodiment. FIG. 4 is a flowchart showing a procedure for substrate processing performed by a processing unit according to an embodiment. FIG. 5 is an explanatory diagram showing an example of a luminance detection process performed by a determination unit. FIG. 6 is a diagram showing an example of a luminance detection result performed by the determination unit. FIG. 7 is a diagram showing the relationship between a wafer position and an etching amount of an underlayer film. FIG. 8 is a flowchart showing a procedure for wafer surface monitoring performed by a substrate processing system according to an embodiment. FIG. 9 is a schematic diagram showing an example of the operation of the substrate processing system. FIG. 10 is a schematic diagram showing an example of the operation of the substrate processing system. FIG. 11 is a schematic diagram showing an example of the configuration of a processing unit according to a first modification of the embodiment. FIG. 12 is a schematic diagram showing an example of the configuration of a processing unit according to a second modification of the embodiment.

[0008] Hereinafter, a substrate processing apparatus and a substrate processing method according to the present disclosure (hereinafter referred to as "embodiments") will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments. Furthermore, the embodiments can be appropriately combined as long as the processing content is not contradictory. Furthermore, the same components in the following embodiments will be assigned the same reference numerals, and redundant explanations will be omitted.

[0009] In the drawings referred to below, for ease of understanding, the X-axis, Y-axis, and Z-axis directions are defined as being orthogonal to each other, and an orthogonal coordinate system is shown in which the positive Z-axis direction is the vertically upward direction. The rotation direction around the vertical axis is also referred to as the θ direction.

[0010] Furthermore, in the following embodiments, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not necessarily mean "constant," "orthogonal," "perpendicular," or "parallel" in the strict sense. In other words, the above expressions allow for deviations due to manufacturing precision, installation precision, etc.

[0011] Conventionally, substrate processing apparatuses have been known that process substrates, such as semiconductor wafers, by rotating the substrates and supplying a processing liquid to the surface of the rotating substrates. For example, such substrate processing apparatuses remove resist films formed on the substrates using a sulfuric acid hydrogen peroxide (SPM) process. The SPM process is performed by supplying an SPM liquid, a processing liquid formed by mixing sulfuric acid and hydrogen peroxide, to the resist film on the substrate.

[0012] The removal efficiency of the resist film can be improved by increasing the temperature of the SPM liquid. However, in an SPM process using a high-temperature SPM liquid, the underlying film exposed at the position where the resist film has been removed by reaction with the SPM liquid on the substrate surface is exposed to the high-temperature SPM liquid for a relatively long time, which may result in increased damage to the underlying film.

[0013] Therefore, there is a need for a technology that can suppress damage to the exposed surface of the substrate during liquid processing such as SPM processing.

[0014] (Embodiment) <Outline of Substrate Processing System> First, a schematic configuration of a substrate processing system 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing a schematic configuration of the substrate processing system 1 according to an embodiment. Note that the substrate processing system 1 is an example of a substrate processing apparatus.

[0015] 1, the substrate processing system 1 includes a loading / unloading station 2 and a processing station 3. The loading / unloading station 2 and the processing station 3 are provided adjacent to each other.

[0016] The loading / unloading station 2 includes a carrier placement unit 11 and a transport unit 12. A plurality of carriers C are placed on the carrier placement unit 11, each of which accommodates a plurality of substrates, in this embodiment, semiconductor wafers W (hereinafter referred to as wafers W), in a horizontal position.

[0017] The transfer section 12 is provided adjacent to the carrier placement section 11 and includes a substrate transfer device 13 and a transfer section 14. The substrate transfer device 13 includes a wafer holding mechanism that holds the wafer W. The substrate transfer device 13 is capable of moving horizontally and vertically and rotating about a vertical axis, and transfers the wafer W between the carrier C and the transfer section 14 using the wafer holding mechanism.

[0018] The processing station 3 is provided adjacent to the transport part 12. The processing station 3 includes a transport part 15 and a plurality of processing units 16. The processing unit 16 is an example of a substrate processing part. The plurality of processing units 16 are provided side by side on both sides of the transport part 15.

[0019] The transfer section 15 includes a substrate transfer device 17 therein. The substrate transfer device 17 includes a wafer holding mechanism that holds the wafer W. The substrate transfer device 17 is capable of moving in the horizontal and vertical directions and rotating about a vertical axis, and transfers the wafer W between the delivery section 14 and the processing unit 16 using the wafer holding mechanism.

[0020] The processing unit 16 performs a predetermined substrate processing on the wafer W transferred by the substrate transfer device 17. The processing unit 16 will be described in detail later.

[0021] The substrate processing system 1 also includes a control device 4. The control device 4 is, for example, a computer, and includes a control unit 18 and a storage unit 19. The storage unit 19 stores programs that control various processes executed in the substrate processing system 1. The control unit 18 controls the operation of the substrate processing system 1 by reading and executing the programs stored in the storage unit 19.

[0022] The program may be recorded on a computer-readable storage medium and installed from the storage medium into the storage unit 19 of the control device 4. Examples of computer-readable storage media include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetic optical disk (MO), and a memory card.

[0023] In the substrate processing system 1 configured as described above, first, the substrate transfer device 13 in the loading / unloading station 2 removes the wafer W from the carrier C placed on the carrier placement unit 11 and places the removed wafer W on the transfer unit 14. The wafer W placed on the transfer unit 14 is then removed from the transfer unit 14 by the substrate transfer device 17 in the processing station 3 and carried into the processing unit 16.

[0024] The wafer W carried into the processing unit 16 is processed by the processing unit 16, and then carried out of the processing unit 16 by the substrate transfer device 17 and placed on the transfer section 14. Then, the processed wafer W placed on the transfer section 14 is returned to the carrier C on the carrier placement section 11 by the substrate transfer device 13.

[0025] <Configuration of Processing Unit> Next, the configuration of the processing unit 16 will be described with reference to Fig. 2. Fig. 2 is a schematic diagram showing an example configuration of the processing unit 16 according to the embodiment. As shown in Fig. 2, the processing unit 16 includes a chamber 20, a liquid processing section 30, a liquid supply section 40, a collection cup 50, an imaging section 60, and a back surface supply section 70 (an example of a cooling section).

[0026] Chamber 20 accommodates liquid processing section 30, liquid supply section 40, collection cup 50, imaging section 60, and back surface supply section 70. A fan filter unit (FFU) 21 is provided on the ceiling of chamber 20. FFU 21 forms a downflow within chamber 20.

[0027] Liquid processing unit 30 includes a holder 31, a support 32, and a drive unit 33, and performs liquid processing on a placed wafer W. Holder 31 holds wafer W horizontally. Support 32 is a member extending in the vertical direction, and its base end is rotatably supported by drive unit 33, with its tip end supporting holder 31 horizontally. Drive unit 33 rotates support 32 about a vertical axis.

[0028] The liquid processing unit 30 rotates the support part 32 using the drive part 33, thereby rotating the holding part 31 supported by the support part 32, and thereby rotating the wafer W held by the holding part 31.

[0029] A gripping portion 31a is provided on the upper surface of a holding portion 31 included in the liquid processing portion 30, and holds the wafer W from the side. The wafer W is held horizontally by the gripping portion 31a while being slightly spaced from the upper surface of the holding portion 31. As a result, the wafer W is held by the holding portion 31 with the surface on which substrate processing is performed facing upward. A resist film is formed on the surface (upper surface) of the wafer W. An underlayer film (e.g., a SiN film) is located below the resist film, and the resist film covers the underlayer film.

[0030] The liquid supply unit 40 supplies a processing liquid to the wafer W. The liquid supply unit 40 includes nozzles 41 a, 41 b, arms 42 a, 42 b that horizontally support the nozzles 41 a, 41 b, respectively, and swivel-elevating mechanisms 43 a, 43 b (an example of a moving unit) that swivel and elevate the arms 42 a, 42 b, respectively. The swivel-elevating mechanism 43 a enables the arm 42 a to move the nozzle 41 a within a predetermined movement range above the wafer W.

[0031] The nozzle 41 a is, for example, a bar nozzle that extends linearly in the horizontal direction. The nozzle 41 a has a length that is shorter than the radius of the wafer W. When the tip end of the nozzle 41 a in the longitudinal direction is positioned above the center of the wafer W, the base end of the nozzle 41 a in the longitudinal direction is positioned above a position that is spaced from the center of the wafer W toward the outer periphery of the wafer W.

[0032] The nozzle 41 a is connected to an SPM liquid supply unit 44 through an SPM liquid supply path 47 , and discharges the SPM liquid supplied from the SPM liquid supply unit 44 onto the surface of the wafer W.

[0033] The SPM liquid supplied from the SPM liquid supply unit 44 is an example of a processing liquid, and is sulfuric acid (H ２ SO ４ ) and hydrogen peroxide (H ２ O ２ ) and a given ratio (e.g., H ２ SO ４ : H ２ O ２The SPM liquid is used, for example, in a process for removing a resist film formed on the surface of a wafer W.

[0034] The SPM liquid supply unit 44 includes a sulfuric acid supply source 44a, a valve 44b, a flow rate regulator 44c, a hydrogen peroxide supply source 44d, a valve 44e, a flow rate regulator 44f, and a confluence unit 44g.

[0035] The sulfuric acid supply source 44a supplies sulfuric acid maintained at a given temperature (for example, 120° C.) to the confluence 44g through a valve 44b and a flow rate regulator 44c. The flow rate regulator 44c regulates the flow rate of the sulfuric acid supplied to the confluence 44g.

[0036] The hydrogen peroxide solution supply source 44d supplies hydrogen peroxide solution to a junction 44g via a valve 44e and a flow rate regulator 44f. The flow rate regulator 44f regulates the flow rate of the hydrogen peroxide solution supplied to the junction 44g. The junction 44g is also connected to an SPM solution supply path 47.

[0037] The SPM liquid produced by mixing the sulfuric acid and the hydrogen peroxide solution at the confluence 44g is supplied to the nozzle 41a through the SPM liquid supply path 47. Because the SPM liquid generates heat when the sulfuric acid and the hydrogen peroxide solution mix, the temperature of the SPM liquid is raised to a temperature (for example, 140°C) higher than that of the sulfuric acid by the time it reaches the nozzle 41a.

[0038] The nozzle 41b is connected to a rinse liquid supply unit 46. The rinse liquid supplied from the rinse liquid supply unit 46 is used for, for example, a rinse process. Examples of the rinse liquid according to the embodiment include hydrogen peroxide, DIW, ozone water, and diluted ammonia water.

[0039] The rinse liquid supply unit 46 includes a rinse liquid supply source 46 a, a valve 46 b, and a flow rate regulator 46 c. The rinse liquid supply source 46 a supplies the rinse liquid to the nozzle 41 b. The flow rate regulator 46 c regulates the flow rate of the rinse liquid supplied to the nozzle 41 b via the valve 46 b.

[0040] Recovery cup 50 is disposed to surround holder 31, and collects the processing liquid scattered from wafer W by the rotation of holder 31. A drain outlet 51 is formed in the bottom of recovery cup 50, and the processing liquid collected by recovery cup 50 is discharged from drain outlet 51 to the outside of processing unit 16.

[0041] In addition, an exhaust port 52 is formed at the bottom of the collection cup 50 to exhaust the gas supplied from the FFU 21 to the outside of the processing unit 16 .

[0042] The imaging unit 60 captures an image of the upper surface of the wafer W. As the imaging unit 60, for example, a CCD camera is used.

[0043] The back surface supply unit 70 is, for example, a long member disposed in a hollow portion that vertically penetrates the holding unit 31 and the support unit 32. A flow path 71 is formed inside the back surface supply unit 70.

[0044] A cooling fluid supply source 72 is connected to the flow path 71 of the back surface supply unit 70 via a valve 73 and a flow rate regulator 74. The cooling fluid supply source 72 supplies a fluid (hereinafter referred to as "cooling fluid") having a lower temperature than the SPM liquid. The cooling fluid supplied from the cooling fluid supply source 72 is, for example, an inert gas such as N2 gas or a rare gas. The cooling fluid supplied from the cooling fluid supply source 72 may also be, for example, a liquid different from the SPM liquid. For example, sulfuric acid can be used as the liquid different from the SPM liquid.

[0045] The back surface supply unit 70 supplies the cooling fluid supplied from the cooling fluid supply source 72 to the back surface (lower surface) of the wafer W via the valve 73, the flow rate regulator 74, and the flow path 71. In this way, the back surface supply unit 70 can cool the wafer W.

[0046] <Configuration of Control Device> Next, the configuration of the control device 4 according to the embodiment will be described with reference to Fig. 3. Fig. 3 is a block diagram showing the configuration of the control device 4 according to the embodiment. As shown in Fig. 3, the control device 4 includes a control unit 18 and a storage unit 19.

[0047] The storage unit 19 is realized by, for example, a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, or a storage device such as a hard disk, an optical disk, etc. The storage unit 19 stores recipe information 191.

[0048] The control unit 18 is realized, for example, by a central processing unit (CPU) or a micro processing unit (MPU) executing various programs stored in a storage device within the control device 4 using RAM as a work area. The control unit 18 is also realized, for example, by an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). In other words, in this disclosure, the control unit 18 refers to an electronic circuit such as a CPU, FPGA, or ASIC, which executes instruction codes stored in memory or is designed as a circuit for a specific application, thereby performing the various control operations described in this specification. The control unit 18 is an example of a control circuit.

[0049] The control unit 18 includes an operation control unit 181, an imaging control unit 182, a determination unit 183, and a cooling control unit 184, and realizes or executes the functions and actions of the control processing described below. Note that the internal configuration of the control unit 18 is not limited to the configuration shown in Fig. 3, and may be any other configuration as long as it is capable of performing substrate processing, etc., as described below.

[0050] The operation control unit 181 controls the processing unit 16 based on the recipe information 191 stored in the storage unit 19 to cause the processing unit 16 to perform a series of substrate processing operations on the wafer W.

[0051] The recipe information 191 is information that indicates the content and order of substrate processing to be performed by the processing unit 16 .

[0052] An example of substrate processing executed under the control of the operation control unit 181 will now be described with reference to Fig. 4. Fig. 4 is a flowchart showing the procedure of substrate processing executed by the processing unit 16 according to the embodiment. The series of substrate processing shown in Fig. 4 is executed in accordance with recipe information 191.

[0053] First, processing unit 16 uses holder 31 of liquid processing unit 30 to hold wafer W, which has been loaded into chamber 20 by substrate transfer device 17 (see FIG. 1 ). Specifically, processing unit 16 uses multiple grippers 31a to grip an edge of wafer W. Thereafter, processing unit 16 rotates wafer W by rotating holder 31 around a vertical axis using drive unit 33.

[0054] Next, the processing unit 16 performs an SPM process (an example of a liquid process) (step S01). In the SPM process, first, the swivel lift mechanism 43a of the liquid supply unit 40 moves the nozzle 41a to a position above the center of the wafer W. Then, the processing unit 16 controls the SPM liquid supply unit 44 and the like to eject the SPM liquid from the nozzle 41a onto the upper surface of the rotating wafer W. The SPM liquid supplied to the center of the wafer W spreads over the entire surface of the wafer W as the wafer W rotates. As a result, the resist film formed on the upper surface of the wafer W is removed by a reaction with the SPM liquid on the upper surface of the wafer W, exposing the base film.

[0055] In addition, during SPM processing, the processing unit 16 may control the rotating lifting mechanism 43a to horizontally move the nozzle 41a between above the center of the wafer W and above the periphery of the wafer W, while ejecting SPM liquid from the nozzle 41a toward the top surface of the rotating wafer W.

[0056] Next, processing unit 16 controls rinse liquid supply unit 46 and the like to rinse wafer W with rinse liquid (step S02). Then, processing unit 16 controls processing unit 16 to dry wafer W (e.g., spin drying) (step S03). Thereafter, wafer W is unloaded from chamber 20 by substrate transfer device 17. This completes the series of substrate processing steps for one wafer W.

[0057] 3, the imaging control unit 182 images the surface of the wafer W during the SPM processing using the imaging unit 60. The imaging control unit 182 images the surface of the wafer W during the SPM processing using the imaging unit 60 multiple times per unit time.

[0058] The determination unit 183 determines whether or not the reaction by the SPM liquid has finished during the SPM processing at each of a plurality of positions on the surface of the wafer W along the radial direction of the wafer W, based on the image captured by the imaging unit 60. Specifically, first, the determination unit 183 detects the brightness at each of a plurality of positions on the surface of the wafer W along the radial direction of the wafer W, based on the image captured by the imaging unit 60, during the SPM processing.

[0059] An example of the luminance detection process by the determination unit 183 will now be described with reference to FIG. 5 . FIG. 5 is an explanatory diagram illustrating an example of the luminance detection process by the determination unit 183. FIG. 5 illustrates the state of the surface (top surface) of the wafer W imaged using the imaging unit 60. During the SPM process, regions where the resist film has already been removed by the reaction with the SPM liquid (hereinafter referred to as "removed regions") and regions where the resist film remains unremoved (hereinafter referred to as "remaining regions") are generated on the surface of the wafer W. The color of the removed regions is closer to white than the color of the remaining regions. That is, in the captured image of the surface of the wafer W, the removed regions have a relatively high luminance, and the remaining regions have a relatively low luminance. Therefore, the luminance at each of multiple positions on the surface of the wafer W along the radial direction of the wafer W indicates the progress of the reaction with the SPM liquid (removal of the resist film). The determination unit 183 detects the luminance at each of multiple (here, five) positions P1 to P5 on the surface of the wafer W along the radial direction of the wafer W. Position P1 is the center position of the wafer W, and position P5 is the peripheral position of the wafer W. Positions P2 to P4 are arranged in this order from the center side of the wafer W toward the peripheral side of the wafer W.

[0060] Fig. 6 is a diagram showing an example of the results of luminance detection by the determination unit 183. The horizontal axis of time in the graph shown in Fig. 6 indicates the elapsed time from time t0 when the nozzle 41a starts to discharge the SPM liquid onto the wafer W. The vertical axis of luminance in the graph shown in Fig. 6 indicates a value obtained by quantifying the color shading at each of multiple (here, five) positions P1 to P5 (see Fig. 5) on the surface of the wafer W into gradations of 0 to 255. A luminance of "0" corresponds to black, and a luminance of "255" corresponds to white.

[0061] As shown in FIG. 6 , for each of the multiple positions P1 to P5 on the surface of the wafer W, the luminance begins to decrease from the initial value toward a value of "0" corresponding to black after a predetermined time has elapsed since the start of discharging the SPM liquid. The luminance then reaches a minimum value. The luminance then increases from the minimum value toward a value of "255" corresponding to white, and stabilizes at a constant final value that is closer to the value of "255" corresponding to white than the initial value. For each of the multiple positions P1 to P5 on the surface of the wafer W, the final luminance value is higher than the initial luminance value. That is, in the detection results shown in FIG. 6 , the final luminance value corresponds to the color of the removal region (see FIG. 5 ), and the initial luminance value corresponds to the color of the remaining region (see FIG. 5 ).

[0062] Alternatively, the determination unit 183 may create an average image of multiple captured images of the surface of the wafer W captured multiple times per unit time using the imaging unit 60, and detect the luminance using the average image. For example, the determination unit 183 adds the luminance of each pixel in the multiple captured images of the surface of the wafer W for each pixel. The determination unit 183 then creates an average image by dividing the added luminance of each pixel by the number of multiple images of the surface of the wafer W, and uses the created average image to detect the luminance at each of multiple positions on the surface of the wafer W along the radial direction of the wafer W. During SPM processing, vapor is generated from the high-temperature SPM liquid present on the surface of the wafer W. The influence of the vapor of the SPM liquid may reduce the resolution of the captured image of the surface of the wafer W, thereby reducing the accuracy of luminance detection. In response to this, by creating an average image of multiple captured images and detecting the luminance from the average image, it is possible to suppress the decrease in accuracy of luminance detection due to the influence of the vapor of the SPM liquid.

[0063] Returning to FIG. 3 , the description of the determination unit 183 continues. When the determination unit 183 detects the luminance at each of the positions P1 to P5 on the surface of the wafer W during the SPM process, it determines whether the reaction (removal of the resist film) caused by the SPM liquid has ended based on the change in the luminance. For example, the determination unit 183 determines whether the reaction (removal of the resist film) caused by the SPM liquid has ended based on the change in the luminance shown in FIG. 6 . Specifically, the determination unit 183 first determines that the reaction caused by the SPM liquid has ended when the luminance at each of the positions P1 to P5 on the surface of the wafer W changes in a predetermined manner. The predetermined change may include, for example, a change in the color of the remaining region (see FIG. 5 ) toward the color of the removed region (see FIG. 5 ). For example, the predetermined change may be a change in the luminance increasing from a minimum value toward a final value corresponding to the removed region. The predetermined change may also be a change in the luminance increasing from a minimum value to a final value corresponding to the removed region. Then, for each of the multiple positions P1 to P5, the determining unit 183 determines that the reaction by the SPM liquid has ended at time points t1 to t5 at which the brightness starts to increase from the minimum value toward the final value corresponding to the removal region.

[0064] The cooling control unit 184 performs a cooling process in which a cooling fluid is supplied from the back surface supply unit 70 to the back surface (lower surface) of the wafer W when it is determined that the reaction by the SPM liquid has ended at at least one of the multiple positions P1 to P5 on the front surface of the wafer W during the SPM process.

[0065] In the SPM process, a relatively high-temperature SPM solution is used to improve the efficiency of removing the resist film, for example, an SPM solution heated to about 140° C.

[0066] During the SPM process, the surface (upper surface) of the wafer W contains a mixture of regions where the resist film has already been removed by a reaction with the SPM liquid (removed regions) and regions where the resist film remains unremoved (remaining regions). Therefore, until the SPM process is completed, the base film exposed in the removed regions is exposed to the high-temperature SPM liquid for a relatively long time. As a result, there is a risk of increased damage to the base film.

[0067] Therefore, in this embodiment, when it is determined that the reaction by the SPM liquid has ended at at least one of the positions P1 to P5 on the front surface of the wafer W during the SPM process, a cooling process is performed in which a cooling fluid is supplied from the back surface supply unit 70 to the back surface (lower surface) of the wafer W. This makes it possible to lower the temperature of the SPM liquid on the front surface (upper surface) of the wafer W, thereby preventing the base film exposed in the removal region from being exposed to the high-temperature SPM liquid. As a result, damage to the base film exposed on the front surface (upper surface) of the wafer W from the SPM liquid can be prevented.

[0068] Here, the specific details of the cooling process will be described. Fig. 7 is a diagram showing the relationship between the wafer position and the etching amount of the base film. In Fig. 7, the "wafer position" on the horizontal axis indicates the distance from the center position of the wafer W when the center position is set as the reference (0 mm). In Fig. 7, the solid line graph shows the results when the cooling process was not performed, i.e., when only the SPM process was performed, and the dashed line graph shows the results when the cooling process was performed.

[0069] 7, it can be seen that the etching amount of the base film is reduced when the cooling process is performed compared to when the cooling process is not performed. This is thought to be because the temperature of the SPM liquid on the front surface (top surface) of the wafer W is lowered by the cooling fluid supplied to the back surface (bottom surface) of the wafer W.

[0070] In this manner, in the substrate processing system 1 according to the embodiment, by performing the cooling process, damage to the base film exposed on the surface of the wafer W during the SPM process can be suppressed.

[0071] Furthermore, in the substrate processing system 1 according to the embodiment, a cooling process is performed when it is determined that the reaction caused by the SPM liquid has ended at at least one of the positions P1 to P5 on the surface of the wafer W during the SPM process. In other words, in the substrate processing system 1, a cooling process is not performed when the reaction caused by the SPM liquid has not ended at any of the positions P1 to P5 on the surface of the wafer W, that is, when the resist film has not been removed from all regions on the surface of the wafer W. Therefore, compared to when a cooling process is performed throughout the entire SPM process, the resist film removal performance of the SPM liquid can be maintained, thereby suppressing a decrease in the resist film removal efficiency.

[0072] <Regarding the Procedure of Wafer Surface Monitoring Processing> Next, the procedure of the wafer surface monitoring processing executed by the substrate processing system 1 according to the embodiment will be described with reference to Fig. 4. Fig. 8 is a flowchart showing the procedure of the wafer surface monitoring processing executed by the substrate processing system 1 according to the embodiment. Figs. 9 and 10 are schematic diagrams showing an example of the operation of the substrate processing system 1. The wafer surface monitoring processing shown in Fig. 8 is executed during SPM processing.

[0073] As shown in FIG. 8, the imaging control unit 182 of the control unit 18 uses the imaging unit 60 to image the surface of the wafer W during the SPM processing (step S101, imaging processing).

[0074] The determination unit 183 of the control unit 18 detects the luminance at each of a plurality of positions P1 to P5 on the surface of the wafer W along the radial direction of the wafer W during the SPM processing based on the image captured by the imaging unit 60 (step S102). The determination unit 183 determines whether the reaction by the SPM liquid (removal of the resist film) has ended based on the change in the detected luminance at each of the plurality of positions P1 to P5 on the surface of the wafer W along the radial direction of the wafer W during the SPM processing (step S103, determination processing).

[0075] If it is not determined that the reaction by the SPM liquid has ended at any of the positions P1 to P5 on the surface of the wafer W during the SPM process (No at step S103), the control unit 18 returns to the process at step S101. Then, the control unit 18 continues to execute the SPM process. That is, the control unit 18 controls the SPM liquid supply unit 44 and the like to continue to discharge the SPM liquid from the nozzle 41 a onto the top surface of the rotating wafer W (see FIG. 9 ).

[0076] On the other hand, if it is determined that the reaction by the SPM liquid has ended at at least one of the multiple positions P1 to P5 on the surface of the wafer W during the SPM processing (step S103, Yes), the cooling control unit 184 of the control unit 18 performs a cooling process (step S104).

[0077] During the SPM process, the surface (upper surface) of the wafer W contains a mixture of regions where the resist film has already been removed by a reaction with the SPM liquid (removed regions) and regions where the resist film remains unremoved (remaining regions). Therefore, until the SPM process is completed, the base film exposed in the removed regions is exposed to the high-temperature SPM liquid for a relatively long time. As a result, there is a risk of increased damage to the base film.

[0078] Therefore, the cooling control unit 184 performs the cooling process when it is determined that the reaction caused by the SPM liquid has ended at at least one of the positions P1 to P5 on the surface of the wafer W during the SPM process. For example, when it is determined that the reaction caused by the SPM liquid has ended at position P1 on the surface of the wafer W, the cooling control unit 184 opens the valve 73 (see FIG. 2) to supply a cooling fluid from the back surface supply unit 70 to the back surface (lower surface) of the rotating wafer W (see FIG. 10). This reduces the temperature of the SPM liquid on the front surface (upper surface) of the wafer W, thereby preventing the base film exposed in the removal region from being exposed to high-temperature SPM liquid. As a result, damage to the base film exposed on the front surface (upper surface) of the wafer W from the SPM liquid can be suppressed.

[0079] Thereafter, the cooling control unit 184 continues to execute the cooling process until the SPM process is completed, and terminates the wafer surface monitoring process upon completion of the SPM process.

[0080] (Modifications) Next, various modifications of the embodiment will be described with reference to Fig. 11 and Fig. 12. Fig. 11 is a schematic diagram showing a configuration example of a processing unit 16 according to Modification 1 of the embodiment. As shown in Fig. 11, the processing unit 16 according to Modification 1 includes a back surface supply unit 70A (an example of a cooling unit) and a moving unit 75 (an example of another moving unit).

[0081] The back surface supply unit 70A is a nozzle having a jet outlet, and is connected to the cooling fluid supply source 72 via a valve 73 and a flow rate regulator 74. The back surface supply unit 70A supplies the cooling fluid supplied from the cooling fluid supply source 72 to the back surface (lower surface) of the wafer W via the valve 73 and the flow rate regulator 74. This allows the back surface supply unit 70A to cool the wafer W.

[0082] The moving unit 75 moves the back surface supply unit 70A along the back surface (lower surface) of the wafer W. The moving unit 75 may have, for example, a guide rail and a linear motion mechanism provided on the upper surface of the holding unit 31, and may move the back surface supply unit 70A along the back surface (lower surface) of the wafer W using the guide rail and the linear motion mechanism.

[0083] During the cooling process, the control unit 18 controls the moving unit 75 to move the back surface supply unit 70A along the back surface (lower surface) of the wafer W, while supplying cooling fluid from the back surface supply unit 70A to the back surface (lower surface) of the wafer W.

[0084] Specifically, the control unit 18 supplies the cooling fluid from the backside supply unit 70A while moving the backside supply unit 70A within a range that overlaps in plan view with the positions where it is determined that the reaction by the SPM liquid has ended among the multiple positions P1 to P5 on the front side of the wafer W. For example, when it is determined that the reaction by the SPM liquid has ended at the positions P1 to P3 on the front side of the wafer W, the control unit 18 moves the backside supply unit 70A within a range that overlaps in plan view with the positions P1 to P3.

[0085] This makes it possible to lower the temperature of the SPM liquid on the surface (upper surface) of the wafer W, thereby further preventing the base film exposed in the removal region from being exposed to the high-temperature SPM liquid, thereby further preventing damage from the SPM liquid to the base film exposed on the surface (upper surface) of the wafer W.

[0086] 12 is a schematic diagram showing a configuration example of a processing unit 16 according to Modification 2 of the embodiment. As shown in FIG. 12, the processing unit 16 according to Modification 2 includes a plurality (five in this case) of back surface supply units 70B1 to 70B5 (examples of cooling units). When no particular distinction is made between the plurality of back surface supply units 70B1 to 70B5, they will be collectively referred to as the "back surface supply unit 70B."

[0087] Each of the multiple back surface supply units 70B1 to 70B5 is a nozzle having a jet port. Back surface supply unit 70B1 is connected to cooling fluid supply source 72 via valve 73a and flow rate regulator 74a. Back surface supply unit 70B2 is connected to cooling fluid supply source 72 via valve 73b and flow rate regulator 74b. Back surface supply unit 70B3 is connected to cooling fluid supply source 72 via valve 73c and flow rate regulator 74c. Back surface supply unit 70B4 is connected to cooling fluid supply source 72 via valve 73d and flow rate regulator 74d. Back surface supply unit 70B5 is connected to cooling fluid supply source 72 via valve 73e and flow rate regulator 74e.

[0088] The multiple back surface supply units 70B1 to 70B5 are arranged corresponding to multiple positions P1 to P5 (see FIG. 5 ) on the front surface of the wafer W. Specifically, the back surface supply unit 70B1 is arranged below position P1 on the front surface of the wafer W and supplies the cooling fluid supplied from the cooling fluid supply source 72 to the back surface (lower surface) of the wafer W located below position P1 via a valve 73 a and a flow rate regulator 74 a. The back surface supply unit 70B2 is arranged below position P2 on the front surface of the wafer W and supplies the cooling fluid supplied from the cooling fluid supply source 72 to the back surface (lower surface) of the wafer W located below position P2 via a valve 73 b and a flow rate regulator 74 b. The back surface supply unit 70B3 is arranged below position P3 on the front surface of the wafer W and supplies the cooling fluid supplied from the cooling fluid supply source 72 to the back surface (lower surface) of the wafer W located below position P3 via a valve 73 c and a flow rate regulator 74 c. The back surface supply unit 70B4 is disposed below a position P4 on the front surface of the wafer W, and supplies the cooling fluid supplied from the cooling fluid supply source 72 to the back surface (lower surface) of the wafer W located below the position P4 via a valve 73d and a flow rate regulator 74d. The back surface supply unit 70B5 is disposed below a position P5 on the front surface of the wafer W, and supplies the cooling fluid supplied from the cooling fluid supply source 72 to the back surface (lower surface) of the wafer W located below the position P5 via a valve 73e and a flow rate regulator 74e. This allows the multiple back surface supply units 70B1 to 70B5 to cool the wafer W.

[0089] In the cooling process, the control unit 18 supplies the cooling fluid to the back surface (lower surface) of the wafer W in order from the back surface supply unit 70B corresponding to the position where it is determined that the reaction by the SPM liquid has ended among the plurality of positions P1 to P5 on the front surface of the wafer W. For example, when it is determined that the reaction by the SPM liquid has ended in the order of positions P1 to P5 for the plurality of positions P1 to P5 on the front surface of the wafer W, the control unit 18 supplies the cooling fluid to the back surface (lower surface) of the wafer W in order from the back surface supply units 70B1 to 70B5.

[0090] This makes it possible to lower the temperature of the SPM liquid on the surface (upper surface) of the wafer W, thereby further preventing the base film exposed in the removal region from being exposed to the high-temperature SPM liquid, thereby further preventing damage from the SPM liquid to the base film exposed on the surface (upper surface) of the wafer W.

[0091] As described above, the substrate processing apparatus (for example, the substrate processing system 1) according to the embodiment includes a holding unit (for example, the holding unit 31), a nozzle (for example, the nozzle 41a), an imaging unit (for example, the imaging unit 60), a cooling unit (for example, the backside supply units 70, 70A, and 70B), and a control circuit (for example, the control unit 18). The holding unit rotatably holds a substrate (for example, a wafer W). The nozzle ejects a processing liquid (for example, an SPM liquid) onto the surface of the substrate held by the holding unit. The imaging unit captures an image of the surface of the substrate held by the holding unit. The cooling unit cools the substrate held by the holding unit. The control circuit executes a liquid process (for example, an SPM process), an imaging process, a determination process, and a cooling process. In the liquid process, the processing liquid is ejected from the nozzle toward the surface of the rotating substrate. In the imaging process, the imaging unit captures an image of the surface of the substrate during the liquid process. The determination process determines whether or not a reaction caused by the processing liquid has been completed at each of a plurality of positions (e.g., positions P1 to P5) on the surface of the substrate along the radial direction of the substrate during the liquid processing, based on the captured image obtained by the imaging process. The cooling process cools the substrate using a cooling unit when it is determined that a reaction caused by the processing liquid has been completed at at least one of the plurality of positions on the surface of the substrate during the liquid processing.

[0092] Therefore, the substrate processing apparatus according to the embodiment can suppress damage to the exposed portion on the surface of the substrate (for example, the base film located under the resist film) during liquid processing.

[0093] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0094] REFERENCE SIGNS LIST 1 Substrate processing system 4 Control device 16 Processing unit 18 Control unit 19 Memory unit 20 Chamber 30 Liquid processing unit 31 Holding unit 40 Liquid supply unit 41a Nozzle 43a Swivel lifting mechanism 44 SPM liquid supply unit 50 Collection cup 60 Imaging unit 70, 70A, 70B Back surface supply unit 75 Moving unit 181 Operation control unit 182 Imaging control unit 183 Determination unit 184 Cooling control unit 191 Recipe information W Wafer

Claims

1. A substrate processing apparatus comprising: a holding unit that rotatably holds a substrate; a nozzle that ejects a processing liquid onto the surface of the substrate held by the holding unit; an imaging unit that images the surface of the substrate held by the holding unit; a cooling unit that cools the substrate held by the holding unit; and a control circuit, wherein the control circuit performs a liquid processing step of ejecting the processing liquid from the nozzle toward the surface of the rotating substrate; an imaging process that uses the imaging unit to image the surface of the substrate during the liquid processing; a determination process that determines whether a reaction caused by the processing liquid has completed for each of a plurality of positions on the surface of the substrate along a radial direction of the substrate based on the images captured by the imaging process; and a cooling process that cools the substrate using the cooling unit when it is determined that the reaction caused by the processing liquid has completed for at least one of the plurality of positions on the surface of the substrate during the liquid processing.

2. The substrate processing apparatus according to claim 1, wherein the control circuit, in the determination process, detects the brightness at each of the plurality of positions on the surface of the substrate based on the image captured by the imaging process, and determines whether or not the reaction by the processing liquid has completed based on the detected change in brightness.

3. The substrate processing apparatus according to claim 1, further comprising a moving unit that moves the nozzle in a horizontal direction, wherein the control circuit controls the moving unit to move the nozzle during the liquid processing, while discharging the processing liquid from the nozzle toward the surface of the rotating substrate.

4. The substrate processing apparatus according to claim 1, wherein the control circuit cools the substrate during the cooling process by supplying a fluid having a lower temperature than the processing liquid from the cooling unit to the back surface of the substrate held by the holding unit.

5. A substrate processing apparatus as described in claim 4, further comprising: another moving unit that moves the cooling unit along the back surface of the substrate; and the control circuit, during the cooling process, controls the other moving unit to move the cooling unit within a range that overlaps in a planar view with a position among the multiple positions on the surface of the substrate where it is determined that the reaction by the processing liquid has ended, while supplying the fluid from the cooling unit to the back surface of the substrate.

6. A substrate processing apparatus as described in claim 4, comprising a plurality of cooling units arranged corresponding to the plurality of positions on the surface of the substrate, and wherein the control circuit supplies the fluid to the back surface of the substrate in the cooling process in order from the cooling unit corresponding to a position among the plurality of positions on the surface of the substrate where it is determined that a reaction by the processing liquid has completed.

7. The substrate processing apparatus according to claim 4, wherein the fluid is a liquid different from the processing liquid.

8. The substrate processing apparatus according to claim 4, wherein the fluid is an inert gas.

9. The substrate processing apparatus according to claim 1, wherein the processing liquid is an SPM liquid, which is a mixture of sulfuric acid and hydrogen peroxide solution.

10. The substrate processing apparatus according to claim 1, wherein the substrate is a substrate having a resist film formed on the surface thereof to cover an undercoat film, and during the liquid processing, the resist film is removed by a reaction with the processing liquid on the surface of the substrate, thereby exposing the undercoat film.

11. A substrate processing method comprising: a liquid processing step of performing liquid processing on a substrate using a processing unit having a holding part that rotatably holds the substrate and a nozzle that ejects a processing liquid onto the surface of the substrate; an imaging step of imaging the surface of the substrate using an imaging part; a determination step of determining whether a reaction caused by the processing liquid has completed at each of a plurality of positions along the radial direction of the substrate on the surface of the substrate during the liquid processing based on the images captured by the imaging step; and a cooling step of cooling the substrate using a cooling part when it is determined that the reaction caused by the processing liquid has completed at at least one of the plurality of positions on the surface of the substrate during the liquid processing.

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