Method for cleaning a pipeline of a single-wafer processing wafer cleaning device

Abstract

Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100), wherein the device comprises: a rotatable platform (11) on which a wafer is arranged, Feed nozzles (12, 12a, 12b) for chemical solutions, through which a chemical solution is fed to the wafer (W) arranged on the platform (11) from one or both of the wafer front and wafer back, Pure water supply nozzles (13, 13a, 13b) through which pure water is supplied to the wafer (W) arranged on the platform (11) from one or both of the wafer front and wafer back, a supply line (14) for chemical solutions, through which the chemical solution is supplied to the supply nozzles (12, 12a, 12b) for chemical solutions, a clean water supply line (15) through which the clean water is supplied to the clean water supply nozzles (13, 13a, 13b), and a waste liquid line (17) through which the supplied chemical solution and the supplied purified water are collected and discharged, the method comprising: a pipeline cleaning step of introducing purified water containing micro-nano bubbles into the purified water supply line (15) to clean a pipeline of the purified water supply line (15), wherein in the pipeline cleaning step the purified water containing micro-nano bubbles is delivered elsewhere than to the wafer (W) to prevent the purified water containing micro-nano bubbles from contacting the surfaces of the wafer (W).

Description

TECHNICAL AREA

[0001] This disclosure relates to a method for cleaning a pipeline of a single-wafer processing wafer cleaning device. BACKGROUND

[0002] Traditionally, silicon wafers are used as substrates for semiconductor devices. A silicon wafer can be obtained by performing a wafer processing process on a single silicon crystalline ingot, grown, for example, using the Czochralski process (CZ process) or similar methods. In the aforementioned processing process, particles, such as polishing powder, are deposited on the surfaces of the silicon wafer, and these particles are removed by cleaning the silicon wafer after the processing (see, for example, PTL 1).

[0003] Cleaning devices for semiconductor wafers, such as silicon wafers, include batch processing cleaning devices, which clean multiple wafers simultaneously, and single-wafer processing cleaning devices, which clean wafers sequentially. Of these, single-wafer processing cleaning devices have been used in recent years because, for example, the required amount of chemical solution is relatively small and cross-contamination between wafers can be avoided, and simultaneous processing of multiple wafers has become more difficult due to increasing wafer diameters.

[0004] Fig. Figure 1 shows an example of a single-wafer processing wafer cleaning device. The in Fig. 1 Wafer cleaning device 100 shown comprises a rotatable platform 11 on which a wafer W to be cleaned is arranged; feed nozzles 12 for chemical solutions for supplying chemical solutions to the front and back surfaces of the wafer W arranged on the platform 11; and pure water feed nozzles 13 for supplying pure water to the front and back surfaces of the wafer W.

[0005] The chemical solution feed nozzles 12 and the pure water feed nozzles 13 are formed by upper nozzles 12a, 13a and lower nozzles 12b, 13b. A chemical solution feed line 14, through which a chemical solution, such as ozonated water, a hydrofluoric acid solution, or an ammonia-hydrogen peroxide mixture, is supplied, is connected to the chemical solution feed nozzles 12, and a pure water feed line 15, through which pure water is supplied, is connected to the pure water feed nozzles 13. The number of such chemical solution feed nozzles 12 provided can correspond to the number of types of chemical solutions used. Furthermore, a rotating cup 16, which collects the chemical solutions and the sprays of pure water during cleaning, is arranged around the platform 11 such that it surrounds the wafer W.

[0006] Using the in Fig. In the wafer cleaning device 100 shown in Figure 1, the wafer W to be cleaned is cleaned, for example, as follows. First, the wafer W is inserted into the wafer cleaning device 100 and positioned on a wafer holder section 11a of the platform 11. Next, while the wafer W is rotated, chemical solutions are sprayed onto the front and back surfaces of the wafer from the chemical solution feed nozzles 12 to clean the wafer W (wafer cleaning step). After the cleaning step is completed, purified water is sprayed from the purified water feed nozzles 13 to rinse the front and back surfaces of the wafer (wafer rinsing step). The chemical solutions and the sprays of purified water from the wafer cleaning step and the wafer rinsing step are collected by the rotating cup 16 and conveyed through a waste liquid line 17 for removal.Finally, the wafer W is rotated at high speed to be dried (wafer drying step). In this way, the wafer W can be cleaned.

[0007] JP 2009-295 655 A discloses a method in which purified water is introduced into a resin water supply line, wherein the purified water contains micro-nano bubbles. These ensure that foreign substances such as metal ions and metal particles are safely removed.

[0008] US 2018 / 0 085 795 A1, US 2003 / 0 205 326 A1 and KR 10 2000 0 009 262 A disclose further purification procedures in the context of semiconductor manufacturing. LIST OF COUNTERPOINTS Patent Literature

[0009] PTL 1: JP 2011- 86 659 A SUMMARY (Technical Problem)

[0010] The wafer W, which has undergone the cleaning step, is delivered to a quality control step for various quality checks. It has been observed that when a silicon wafer is repeatedly cleaned using the single-wafer processing wafer cleaning device, the number of particles detected on the wafer surfaces in the quality control step suddenly increases.

[0011] This disclosure was made in view of the above problem and may be helpful in providing a method for preventing a sudden increase in the number of particles detected on wafer surfaces, even when a wafer is repeatedly cleaned using a single-wafer processing wafer cleaning device. (Solution to the problem)

[0012] The following features are proposed for solving the above problem. [1] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device, wherein the device comprises: a rotating platform on which a wafer is placed, Feed nozzles for chemical solutions, through which a chemical solution is fed to the wafer arranged on the platform from one or both the wafer front and the wafer back, Pure water supply nozzles, through which pure water is supplied to the wafer arranged on the platform from one or both the front and back of the wafer, a supply line for chemical solutions, through which the chemical solution is supplied to the supply nozzles for chemical solutions, a pure water supply line, through which the pure water is supplied to the pure water supply nozzles, and a waste liquid line through which the supplied chemical solution and the supplied purified water are collected and discharged, the method comprising: a pipeline cleaning step of introducing pure water containing micro-nano bubbles into the pure water supply line to clean a pipeline of the pure water supply line. [2] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to [1] above, wherein the clean water supply line is provided with a three-way valve, wherein one of two outlet openings of the three-way valve is connected to the clean water supply nozzle, and the other outlet opening is connected to the waste liquid line; and in the pipeline cleaning step, the clean water containing micro-nano bubbles is introduced into the clean water supply line, wherein the outlet opening of the three-way valve is selected on the side of the waste liquid line. [3] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to above [1], wherein in the pipeline cleaning step the pure water supply nozzle is withdrawn from the wafer and the pure water containing micro-nano bubbles is supplied to a treatment cup which is arranged adjacent to the platform and connected to the waste liquid line. [4] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to [1] above, wherein a three-way valve is provided between the clean water feed nozzle on the wafer back and the clean water feed line; and one of two outlet ports of the three-way valve is connected to the clean water feed nozzle on the wafer back, and the other outlet port is connected to the waste liquid line, and in the pipeline cleaning step, while the micro-nano-bubble-containing purified water is introduced into the purified water supply line, with the outlet port of the three-way valve selected on the side of the waste liquid line; the purified water supply nozzle on the wafer front is pulled away from the wafer, and the micro-nano-bubble-containing purified water is fed to a treatment cup located adjacent to the platform and connected to the waste liquid line. [5] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to one of the above [1] to [4], where the pipeline cleaning step is performed each time a wafer is cleaned. [6] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to one of the preceding [1] to [5], wherein the method comprises: a wafer cleaning step of performing a cleaning by spraying the chemical solution onto one or both of a front surface and a back surface of a wafer; a wafer rinsing step of performing a rinse by spraying the pure water, which is free of micro-nano bubbles, onto one or both of the front and back surfaces of the wafer; and a wafer drying step of performing drying by rotating the wafer without either of the chemical solution and the pure water, which is free of micro-nano bubbles, being introduced onto the wafer surfaces, where the pipeline cleaning step is carried out simultaneously with the wafer drying step. [7] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to [6] above, the pipeline cleaning step includes: a first step in the introduction of the pure water containing micro-nano bubbles; and a second step of adding pure water that is free of micro-nano bubbles, after the first step. [8] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to one of the above [1] to [4], the pipeline cleaning step is set up in such a way that it is carried out automatically at a predetermined cleaning interval. [9] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to [8] above, where the specified cleaning interval is automatically set depending on the result of an evaluation of the number of particles on the wafer.

[10] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to [8] above, wherein particles contained in the purified water flowing through the purified water supply nozzle are monitored using a particle counter used to count particles in a liquid, and the predetermined cleaning interval is set depending on the number of monitored particles. (Beneficial effect)

[0013] This disclosure can prevent a sudden increase in the number of particles detected on wafer surfaces, even when the cleaning of a wafer is repeatedly performed using a single-wafer processing wafer cleaning device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings show: Fig. 1 a diagram illustrating an example of a single-wafer processing wafer cleaning device; Fig. 2 a diagram in which a device generating micro-nano bubbles is connected to a pure water supply line of the in Fig. 1 is connected to the single wafer processing wafer cleaning device shown; Fig. 3A and Fig. 3B Diagrams illustrating a method for cleaning a pipeline of a single-wafer processing wafer cleaning device of this disclosure, wherein Fig. 3A is a side view and Fig. 3B is a top view; Fig. 4 a diagram illustrating another example of a method for cleaning a pipeline of a single-wafer processing wafer cleaning device of this disclosure; Fig. 5 a flowchart of a typical wafer cleaning process using a single-wafer processing wafer cleaning device in which a pipeline cleaning step of this disclosure is used; and Fig. 6A and Fig. 6B Diagrams showing the variation in the number of particles on silicon wafers when silicon wafers are cleaned successively, each referring to the conventional example and the example of the invention, respectively. DETAILED DESCRIPTION

[0015] Embodiments of this disclosure will now be described with reference to the drawings.This disclosure proposes a method for cleaning a pipeline of a single-wafer processing wafer cleaning device, comprising: a rotatable platform on which a wafer is arranged; chemical solution feed nozzles through which chemical solutions are supplied to the wafer arranged on the platform from one or both of the wafer's front and back faces; purified water feed nozzles through which purified water is supplied to the wafer arranged on the platform from one or both of the wafer's front and back faces; a chemical solution feed line through which the chemical solutions are supplied to the chemical solution feed nozzles; a purified water feed line through which the purified water is supplied to the purified water feed nozzles; and a waste liquid line through which the supplied chemical solution and the supplied purified water are collected and discharged.This process includes a pipeline cleaning step of introducing pure water containing micro-nano bubbles into the pure water supply line to clean the pure water supply line pipeline.

[0016] Considering that when a wafer W was repeatedly cleaned using a single-wafer processing wafer cleaning device, the number of particles detected on the surfaces of wafer W suddenly increased, as described above, the inventor of the present invention carefully investigated the cause of this. The inventor therefore considered that when clean water was supplied to wafer W during the wafer rinsing step, particles that had accumulated inside the pure water supply line 15 would have been discharged and deposited on the surfaces of the wafer.

[0017] In particular, purified water used in the wafer rinsing step of the cleaning process is diverted from the factory's main purified water supply line to be fed to cleaning equipment, and this feeding is carried out while metals and particles are removed using a filter. However, when removing particles using a filter as described above, the particles are in most cases not sufficiently removed, for example, depending on the filter orifice diameter. Furthermore, when a new purified water supply line 15 is installed, the inside of the line is cleaned by supplying purified water to the line for a period of time, and the line is put into use after it meets a predetermined requirement, when the quality of the purified water flowing inside has been tested; however, the line is often not subsequently maintained.Accordingly, it is possible that particles accumulated in the connections and valves of the clean water supply line 15 in each cleaning device are then suddenly discharged to be delivered to the surfaces of the wafer W in the wafer rinsing step and deposited on the wafer W.

[0018] Based on the foregoing assumption, the inventor of the present invention carefully investigated ways to remove the particles adhering to the interior of the pure water supply line 15 by cleaning the pipe. Flushing by continuously supplying pure water to the pure water supply line 15 can be effective, but is time-consuming and would not sufficiently remove particles accumulated in the connections and valves. Therefore, the inventor of the present invention carefully investigated methods other than flushing and devised a cleaning process for the interior of the pure water supply line 15 by supplying pure water containing micro-nano bubbles (which may also be referred to below as "micro-nano bubble-containing water").

[0019] Micro-nano bubble-containing water is a gas-liquid mixture that is pure water containing tiny micrometer and nanometer-sized bubbles. In recent years, it has been used as a cleaning solution to remove deposits that have accumulated on the surface of an object. For example, JP 2013-248582 A describes the use of micro-nano bubble-containing water as a cleaning solution for cleaning electronic materials enclosing a wafer.

[0020] However, during the wafer rinsing step, when the micro-nano-bubble-containing water introduced into the purified water supply line 15 is supplied to the surfaces of the wafer W from the purified water supply nozzles 13, the particles removed from the purified water supply line 15 by micro-nano-bubbles would be deposited on the surfaces of the wafer W. Therefore, the inventor of the present invention found that the particles could be effectively removed in a short time by introducing micro-nano-bubble-containing water into the water supply line 15 to deliver the micro-nano-bubble-containing water to a location other than the wafer W, and this disclosure was made accordingly.Although described in detail below, “delivering micro-nano-bubble-containing water to a location other than the wafer W” now refers, for example, to delivering the micro-nano-bubble-containing water directly to the waste liquid line 17 via a three-way valve, thereby preventing contact with the surface of the wafer W; and delivering the micro-nano-bubble-containing water to the upper nozzle 13a of the clean water supply nozzles 13 after the upper nozzle 13a has been retracted (pulled away) from above the wafer W, thereby delivering it to a treatment cup that is directly connected to the waste liquid line 17.

[0021] In this disclosure, the diameter of the micro-nano-bubbles in the water containing micro-nano-bubbles is preferably 0.1 µm or more and 10 µm or less. The micro-nano-bubbles with diameters in the aforementioned range can effectively remove the particles deposited on the surfaces of the wafer W.

[0022] Furthermore, the number density of the micro-nano bubbles is preferably 1 × 10 5 / cm 3 or more and 1 × 10 10 / cm 3 or less. If the number density of the micro-nano-bubbles is 1 × 10 5 / cm 3 or more, the cleaning effect on the interior of the pure water supply line 15 can be increased. Although the upper limit of the number density of micro-nano-bubbles is not limited with regard to the cleaning effect, since micro-nano-bubbles with a density of 1 × 10 10 / cm 3 Exceeding the number density, they are hardly formed, therefore the number density is preferably 1 × 10 10 / cm 3 or less.

[0023] The flow rate of the micro-nano-bubble-containing water is preferably 0.5 l / min or more and 2.0 l / min or less. If the flow rate of the micro-nano-bubble-containing water is 0.5 l / min or more, the cleaning effect on the interior of the pure water supply line 15 can be increased. Since the cleaning effect remains unchanged even if the flow rate of the micro-nano-bubble-containing water exceeds 2.0 l / min, the flow rate of the micro-nano-bubble-containing water is also 2.0 l / min or less.

[0024] The time during which the micro-nano-bubble-containing water is introduced is set to a time greater than or equal to the time it takes to replace the water in the pure water supply nozzles 13 and less than or equal to the time that does not affect the productivity of the wafer W. Specifically, the time during which the micro-nano-bubble-containing water is introduced is preferably 10 seconds or more and 30 seconds or less. If the introduction time of the micro-nano-bubble-containing water is 10 seconds or more, the cleaning effect on the interior of the pure water supply line 15 can be increased. Furthermore, even if the introduction time of the micro-nano-bubble-containing water exceeds 30 seconds, the cleaning effect remains unchanged; therefore, the introduction time of the micro-nano-bubble-containing water is preferably 30 seconds or less.

[0025] The purity of the micro-nano-bubble-containing pure water is not limited as long as an appropriate product quality can be achieved, and can be of so-called pure water level (for example, specific resistance: 0.1 MΩ·cm to 15 MΩ·cm), or can be of ultrapure water level (for example, specific resistance: higher than 15 MΩ·cm).

[0026] The aforementioned micro-nano-bubble-containing water can be generated by connecting a micro-nano-bubble-generating device 18 to the pure water supply line 15, as shown in Fig. 2 shown, and micro-nano bubbles generated by the micro-nano bubble generating device 18 are mixed into the pure water in the pure water supply line 15.

[0027] Introducing the micro-nano-bubble-containing water, generated as described above, into the pure water supply line 15 can clean the piping of the pure water supply line 15, thereby removing the particles deposited inside the piping.

[0028] Regarding the position at which the aforementioned micro-nano-bubble-containing water is introduced, since the timing of the wafer rinsing step varies in each single-wafer processing wafer cleaning device 100, if the micro-nano-bubble-containing water is introduced upstream of the branching point in the pure water supply line 15, where the water is divided into each single-wafer processing wafer cleaning device, the micro-nano-bubble-containing water can be supplied to the wafer W. Accordingly, the micro-nano-bubble-containing water is preferably introduced into the pure water supply line 15 of each cleaning device (that is, downstream of the aforementioned branching point).

[0029] Regarding the position at which the micro-nano-bubble-containing water is dispensed, since the purified water supply line 15 is connected to the purified water supply nozzles 13, the micro-nano-bubble-containing water introduced into the purified water supply line 15 is sprayed from the purified water supply nozzles 13. At this point, when the micro-nano-bubble-containing water is sprayed onto the wafer W, with the wafer W arranged on the platform 11 being rotated, the particles removed by the micro-nano-bubble-containing water would be deposited on the surfaces of the wafer W.

[0030] In a typical single-wafer processing wafer cleaning device, as in Fig. 3A and Fig. As shown schematically in Figure 3B, when the upper nozzle 12a of the chemical solution feed nozzles 12 and the upper nozzle 13a of the purified water feed nozzles 13 are withdrawn from the wafer W, the treatment cup 19, which collects the chemical solution and purified water dripping from the upper nozzles 12a and 13a, is positioned such that contact between the chemical solution and purified water collected by the treatment cup 19 and the wafer W is prevented. Furthermore, the bottom of the treatment cup 19 is provided with an outlet opening leading to the waste liquid line 17, and the chemical solution and purified water collected by the treatment cup 19 are discharged into the waste liquid line 17.The treatment cup 19 is arranged adjacent to the platform 11, leaving a space into which the upper nozzles 12a and 13a can be withdrawn, and is arranged, for example, adjacent to the outside of the rotating cup 16. Therefore, as in . Fig. Figure 3B shows that while the upper nozzle 13a of the clean water supply nozzles 13 is rotated radially along the wafer W to be pulled away from it, water containing micro-nano bubbles is introduced into the clean water supply line 15. This allows the clean water to be delivered, after cleaning, from a spray hole 13c of the upper nozzle 13a to the treatment cup 19. This discharge of the micro-nano bubble-containing water into the waste liquid line prevents it from contacting the wafer surface. As a result, the interior of the clean water supply line 15 can be cleaned, while preventing the particles removed from the interior of the clean water supply line 15 from being deposited on the surface of the wafer W.It should be noted that the design of the treatment cup 19 is not limited to the above, and the treatment cup can be designed such that it delivers the micro-nano-bubble-containing purified water received from the upper nozzle 13a to the waste liquid line 17 while preventing contact with the wafer W.

[0031] As schematically in Fig. As shown in Figure 4, the pure water supply line 15 is provided with a three-way valve 20, and one of the two outlet ports of the three-way valve 20 is connected to the pure water supply nozzle 13, and the other outlet port is connected to the waste liquid line 17; and water containing micro-nano bubbles is introduced into the pure water supply line 15, with the outlet port of the three-way valve 20 connected to the waste liquid line 17 being selected, so that the water containing micro-nano bubbles can be discharged into the waste liquid line 17 while preventing contact with the surfaces of the wafer W. As a result, the interior of the pure water supply line 15 can be cleaned while preventing the particles removed from the interior of the pure water supply line 15 from being deposited on the surfaces of the wafer W.

[0032] Alternatively, a three-way valve 20 is provided between the lower nozzle 13b, which represents the pure water supply nozzle on the back of the wafer, and the pure water supply line 15; one of the two outlet ports of the three-way valve 20 is connected to the lower nozzle 13b, and the other outlet port is connected to the waste liquid line 17; and in the pipeline cleaning step, while micro-nano-bubble-containing water is introduced into the pure water supply line 15, with the outlet port of the three-way valve 20 on the side of the waste liquid line 17 selected, the upper nozzle 13a, which represents the pure water supply nozzle on the front of the wafer, is pulled away from the wafer W, thereby supplying the micro-nano-bubble-containing water to the treatment cup 19, which is located adjacent to the platform 11 and is connected to the waste liquid line 17.

[0033] The preceding pipeline cleaning step is preferably performed after each cleaning of a wafer W. This can ensure that a sudden increase in the particles deposited on the wafer W is prevented.

[0034] It should be noted, however, that the pipe cleaning step is not necessarily performed every time a wafer W is cleaned and can be configured to be performed automatically at a predetermined cleaning interval. The predetermined cleaning interval can be set, for example, by first determining the interval in which particles suddenly increase and selecting an interval that is shorter than this interval. Alternatively, the predetermined cleaning interval can be automatically set based on the result of an evaluation of the number of particles on the wafer W during the quality control step.Furthermore, particles contained in the purified water flowing through the purified water supply nozzles 13 are monitored using a particle counter designed for counting particles in a liquid, and the predetermined cleaning interval can be adjusted depending on the number of monitored particles. Monitoring of the particles contained in the purified water is preferably carried out when the contents of the purified water supply line 15 are replaced with purified water by supplying micro-nano-bubble-free purified water to the purified water supply line 15 after the discharge of the micro-nano-bubble-containing water; when a sham discharge of micro-nano-bubble-free purified water is performed prior to wafer cleaning; or the like.

[0035] Furthermore, the pipeline cleaning step of this disclosure can be appropriately combined with an existing wafer cleaning process (i.e., a cleaning step in a wafer manufacturing process). Fig. Figure 5 shows a flowchart of a typical wafer cleaning process using a single-wafer processing wafer cleaning device, in which the pipeline cleaning step of this disclosure is used. As in Fig. Figure 5 shows a typical wafer cleaning process using a single-wafer processing wafer cleaning device: a wafer cleaning step S1 of performing a cleaning by spraying the chemical solution onto one or both of a front and a back surface of a wafer; a wafer rinsing step S2 of performing a rinsing by spraying pure water, free of micro-nano bubbles, onto one or both of the front and back surfaces of the wafer; and a wafer drying step S3 of performing a drying by rotating the wafer without spraying either of the chemical solution and the pure water, free of micro-nano bubbles, onto the wafer surfaces.The pipeline cleaning step S4 of this disclosure is preferably carried out simultaneously with the wafer drying step S3 of the aforementioned wafer cleaning process, so that cleaning of the wafer W and cleaning of the pipeline of the single-wafer processing wafer cleaning device can be carried out at the same time, while preventing the particles removed from the interior of the pipeline by the micro-nano-bubble-containing water from being deposited on the wafer W. It should be noted that "pure water free of micro-nano-bubbles" means pure water that is substantially free of micro-nano-bubbles, into which no micro-nano-bubbles are mixed by the micro-nano-bubble-generating device.

[0036] As described above, when the pipeline cleaning step of this disclosure is combined with the steps of the wafer cleaning process, the step of supplying purified water free of micro-nano-bubbles (second step) is preferably carried out after the step of supplying purified water containing micro-nano-bubbles (first step). This can prevent the remaining water containing micro-nano-bubbles from being delivered to the wafer W. EXAMPLES

[0037] Examples of this revelation will now be described; however, this revelation is not limited to the examples below. (Conventional example)

[0038] Nine hundred silicon wafers were successively processed using the in Fig. The silicon wafers were cleaned in the single-wafer processing wafer cleaning device 100 shown in Figure 1. Specifically, for each silicon wafer to be cleaned, the silicon wafer was inserted into the single-wafer processing wafer cleaning device 100 and positioned on the platform 11. Next, while the platform 11 was rotated, the front and back surfaces of the silicon wafer were cleaned by alternately and repeatedly spraying aqueous 1% hydrofluoric acid solution and ozonated water from the chemical solution feed nozzles 12 (wafer cleaning step). Subsequently, purified water was supplied from the purified water feed line 15 to rinse the front and back surfaces of the silicon wafer (wafer rinsing step). Afterward, the silicon wafer was rotated at high speed to dry it (wafer drying step).Subsequently, particles deposited on the surfaces of the cleaned silicon wafer were counted as light spot defects (LPDs) using a surface inspection system (Surfscan SP2, manufactured by KLA-Tencor Corporation). The detection mode used at this time was the DCO (Darkfield Composite Oblique) mode, and LPDs with a size of 45 nm or larger were counted. The results are presented in [reference missing]. Fig. 6A is shown. (Example of an invention)

[0039] As in the conventional example, 900 silicon wafers were cleaned sequentially. However, it should be noted that the silicon wafers were cleaned using the process described in the example. Fig. 2 single wafer processing wafer cleaning device 100 shown were cleaned, and at this time the cleaning of the pure water supply line 15 was carried out simultaneously with the wafer drying step, as shown in Fig. Figure 5 (pipeline cleaning step). In particular, in the pipeline cleaning step, a bubble-generating device, obtained by modifying a typical bubble device to have a structure applicable to pure water, was connected to the pure water supply line 15, and water containing micro-nano bubbles was supplied to the pure water supply line 15. All other conditions were the same as in the conventional example. The number of detected LPDs is shown in Fig. 6B is indicated.

[0040] As in Fig. As specified in 6A, the number of LPDs, that is, the number of particles, suddenly increased in the conventional example at a frequency of approximately every 600 silicon wafers. In the example as in Fig. In contrast, as stated in 6B, the number of particles did not suddenly increase even though 900 silicon wafers were cleaned consecutively. INDUSTRIAL APPLICABILITY

[0041] This disclosure can prevent a sudden increase in the number of particles detected on wafer surfaces, even when a wafer W is repeatedly cleaned using a single-wafer processing wafer cleaning device, which is why the method for cleaning a pipeline of a single-wafer processing wafer cleaning device according to this disclosure is useful in the semiconductor industry. LIST OF REFERENCE MARKS 11 Platform 11a Wafer holder section 12 feed nozzles for chemical solutions 12a, 13a Upper nozzle 12b, 13b Lower nozzle 13 Pure water feed nozzle 13c spray hole 14 Supply line for chemical solutions 15 Pure water supply line 16 rotating cups 17 Waste liquid line 18 Micro-nano bubble-generating device 19 treatment cups 20 Three-way valve 100 single wafer processing wafer cleaning devices W Wafer

Claims

[1] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100), wherein the device comprises: a rotatable platform (11) on which a wafer is arranged, Feed nozzles (12, 12a, 12b) for chemical solutions, through which a chemical solution is fed to the wafer (W) arranged on the platform (11) from one or both of the wafer front and wafer back, Pure water supply nozzles (13, 13a, 13b) through which pure water is supplied to the wafer (W) arranged on the platform (11) from one or both of the wafer front and wafer back, a supply line (14) for chemical solutions, through which the chemical solution is supplied to the supply nozzles (12, 12a, 12b) for chemical solutions, a clean water supply line (15) through which the clean water is supplied to the clean water supply nozzles (13, 13a, 13b), and a waste liquid line (17) through which the supplied chemical solution and the supplied purified water are collected and discharged, the method comprising: a pipeline cleaning step of introducing purified water containing micro-nano bubbles into the purified water supply line (15) to clean a pipeline of the purified water supply line (15), wherein in the pipeline cleaning step the purified water containing micro-nano bubbles is delivered elsewhere than to the wafer (W) to prevent the purified water containing micro-nano bubbles from contacting the surfaces of the wafer (W). [2] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100) according to claim 1, wherein the pure water supply line (15) is provided with a three-way valve (20), wherein one of two outlet openings of the three-way valve (20) is connected to the pure water supply nozzle (13, 13a, 13b), and the other outlet opening is connected to the waste liquid line (17); and in the pipeline cleaning step, the pure water containing micro-nano bubbles is introduced into the pure water supply line (15), wherein the outlet opening of the three-way valve is selected on the side of the waste liquid line (17). [3] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100) according to claim 1, wherein in the pipeline cleaning step the pure water supply nozzle (13, 13a, 13b) is withdrawn from the wafer (W) and the pure water containing micro-nano-bubbles is supplied to a treatment cup (19) which is arranged adjacent to the platform (11) and is connected to the waste liquid line (17). [4] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100) according to claim 1, wherein a three-way valve (20) is provided between the clean water feed nozzle (13, 13a, 13b) on the wafer back and the clean water feed line (15); and one of two outlet ports of the three-way valve (20) is connected to the clean water feed nozzle (13, 13a, 13b) on the wafer back, and the other outlet port is connected to the waste liquid line (17), and in the pipeline cleaning step, while the purified water containing micro-nano-bubbles is introduced into the purified water supply line (15), the outlet opening of the three-way valve (20) being selected on the side of the waste liquid line (17); the purified water supply nozzle (13, 13a, 13b) on the wafer front is pulled away from the wafer (W), and the purified water containing micro-nano-bubbles is fed to a treatment cup (19) located adjacent to the platform (11) and connected to the waste liquid line (17). [5] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100) according to any one of claims 1 to 4, wherein the pipeline cleaning step is performed each time after cleaning a wafer (W). [6] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100) according to any one of claims 1 to 5, wherein the method comprises: a wafer cleaning step of performing a cleaning by spraying the chemical solution onto one or both of a front surface and a back surface of a wafer(W); a wafer rinsing step of performing a rinse by spraying the pure water, which is free of micro-nano bubbles, onto one or both of the front and back surfaces of the wafer (W); and a wafer drying step of performing drying by rotating the wafer without either of the chemical solution and the purified water, which is free of micro-nano bubbles, being supplied to the wafer surfaces, wherein the pipeline cleaning step is performed simultaneously with the wafer drying step. [7] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100) according to claim 6, wherein the pipeline cleaning step comprises: a first step in the introduction of the pure water containing micro-nano bubbles; and a second step of adding pure water that is free of micro-nano bubbles, after the first step. [8] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100) according to any one of claims 1 to 4, wherein the pipeline cleaning step is arranged such that it is carried out automatically at a predetermined cleaning interval. [9] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100) according to claim 8, wherein the specified cleaning interval is automatically set depending on the result of an evaluation of a number of particles on the wafer (W). [10] Method for cleaning a pipeline of a single-wafer processing wafer cleaning device (100) according to claim 8, wherein particles contained in the purified water flowing through the purified water supply nozzle (13, 13a, 13b) are monitored using a particle counter used to count the particles in a liquid, and the predetermined cleaning interval is set depending on the number of monitored particles.

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