Method for washing piping of a single wafer cleaning apparatus

Abstract

The present invention provides a method that can suppress a sudden increase in the number of particles detected on the surface of a wafer even when washing of a wafer (W) is repeatedly performed using a single-wafer wafer washing device. The present invention is characterized in that a single-wafer wafer washing device (100) is provided with a table (11) that can rotate, a chemical liquid supply nozzle (12) that supplies chemical liquid to a wafer (W) placed on the table (11), a pure water supply nozzle (13) that supplies pure water to the wafer (W) placed on the table (11), a chemical liquid supply line (14) that supplies chemical liquid to the chemical liquid supply nozzle (12), a pure water supply line (15) that supplies pure water to the pure water supply nozzle (13), and a waste liquid line (17) that discharges the supplied chemical liquid and pure water by recovering them. The present invention includes a pipe washing process of introducing pure water containing micro-nano bubbles into the pure water supply line (15) of the single-wafer wafer washing device (100) to wash the piping of the pure water supply line (15).

Description

TECHNICAL FIELD

[0001] The present application relates to a washing method of a piping of a single wafer washing apparatus. BACKGROUND

[0002] Conventionally, a silicon wafer is used as a substrate of a semiconductor device. A single crystal silicon ingot grown by a Czochralski (CZ) method or the like is subjected to a wafer processing treatment, and thus a silicon wafer is obtained. At the time of the above processing treatment, particles such as polishing powder adhere to the surface of the silicon wafer, and thus a washing treatment is performed on the silicon wafer after the processing treatment to remove the particles (see, for example, Patent Literature 1).

[0003] Among washing apparatuses for semiconductor wafers such as silicon wafers, there are batch-type washing apparatuses in which a plurality of wafers are simultaneously washed, and single-wafer-type washing apparatuses in which wafers are washed one by one. In recent years, the single-wafer-type washing apparatuses are being used because the amount of necessary chemical liquid is small, mutual contamination between wafers can be avoided, and it is difficult to simultaneously process a plurality of wafers due to large-diameter.

[0004] Figure 1 An example of a single-wafer-type wafer washing apparatus is shown. Figure 1 The wafer washing apparatus 100 shown in FIG. 1 is provided with a rotatable table 11 on which a wafer W to be washed is placed, a chemical liquid supply nozzle 12 that supplies a chemical liquid to the front and back surfaces of the wafer W placed on the table 11, and a pure water supply nozzle 13 that supplies pure water to the front and back surfaces of the wafer W.

[0005] The chemical liquid supply nozzle 12 and the pure water supply nozzle 13 are each composed of an upper nozzle 12a, 13a and a lower nozzle 12b, 13b. The chemical liquid supply nozzle 12 is connected to a chemical liquid supply line 14 that supplies a chemical liquid such as ozone water, a hydrofluoric acid solution, or hydrogen peroxide, and the pure water supply nozzle 13 is connected to a pure water supply line 15 that supplies pure water. In addition, a plurality of chemical liquid supply nozzles 12 can be prepared for each type of chemical liquid. Further, around the table 11, a rotary cup 16 that collects chemical liquid and pure water scattered during washing is disposed so as to surround the wafer W.

[0006] Utilization Figure 1The wafer cleaning apparatus 100 shown in FIG. 1 cleans a wafer W as a cleaning target as follows. First, the wafer W is introduced into the wafer cleaning apparatus 100 and placed on the wafer holding portion 11a of the stage 11. Next, while the wafer W is being rotated, a chemical liquid is sprayed from the chemical liquid supply nozzle 12 toward both the front and back surfaces of the wafer W to clean the wafer W (wafer cleaning step). After the cleaning step, pure water is sprayed from the pure water supply nozzle 13 toward both the front and back surfaces of the wafer W to rinse the wafer W (wafer rinsing step). The chemical liquid and the pure water scattered during the wafer cleaning step and the wafer rinsing step are caught by the rotating cup 16 and recovered by the waste liquid line 17 to be discharged. Finally, the wafer W is rotated at high speed to dry the wafer W (wafer drying step). In this way, the wafer W can be cleaned.

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-086659

[0008] The wafer W that has undergone the cleaning step is transported to a quality inspection step to be subjected to various quality inspections, but it has been found that, when the cleaning of a silicon wafer is repeatedly performed using a single-wafer type wafer cleaning apparatus, the number of particles detected at the surface of the wafer suddenly increases in the quality inspection step. SUMMARY

[0009] The present application has been made in view of the above problems, and has an object to provide a method that can suppress a sudden increase in the number of particles detected at the surface of a wafer even when the cleaning of the wafer is repeatedly performed using a single-wafer type wafer cleaning apparatus.

[0010] The present application that solves the above problems is described below.

[0011] [1] A cleaning method of piping of a single-wafer type wafer cleaning apparatus, which is a method of cleaning piping of a single-wafer type wafer cleaning apparatus, the single-wafer type wafer cleaning apparatus including a stage, a chemical liquid supply nozzle, a pure water supply nozzle, a chemical liquid supply line, a pure water supply line, and a waste liquid line, the stage being capable of rotating and on which a wafer is placed, the chemical liquid supply nozzle supplying a chemical liquid to a wafer placed on the stage from a front surface side and / or a back surface side of the wafer, the pure water supply nozzle supplying pure water to the wafer placed on the stage from the front surface side and / or the back surface side of the wafer, the chemical liquid supply line supplying the chemical liquid to the chemical liquid supply nozzle, the pure water supply line supplying the pure water to the pure water supply nozzle, and the waste liquid line recovering and discharging the supplied chemical liquid and pure water, the cleaning method of piping of the single-wafer type wafer cleaning apparatus being characterized by including a piping cleaning step of introducing pure water containing micro-nano bubbles into the pure water supply line to clean piping of the pure water supply line.

[0012] [2] The pipe washing method of the single-wafer wafer washing apparatus according to the preceding [1], characterized in that a three-way valve is provided at the pure water supply line, one of the two outlets is connected to the pure water supply nozzle, and the other is connected to the waste liquid line, and in the pipe washing process, pure water containing the micro-nano bubbles is introduced into the pure water supply line with the outlet of the three-way valve switched to the waste liquid line side.

[0013] [3] The pipe washing method of the single-wafer wafer washing apparatus according to the preceding [1], characterized in that in the pipe washing process, the pure water supply nozzle is retracted from the wafer, and pure water containing the micro-nano bubbles is supplied to a treatment cup connected to the waste liquid line and provided adjacent to the table.

[0014] [4] The pipe washing method of the single-wafer wafer washing apparatus according to the preceding [1], characterized in that a three-way valve is provided between the pure water supply nozzle on the back side of the wafer and the pure water supply line, one of the two outlets is connected to the pure water supply nozzle on the back side of the wafer, and the other is connected to the waste liquid line, and in the pipe washing process, pure water containing the micro-nano bubbles is introduced into the pure water supply line with the outlet of the three-way valve switched to the waste liquid line side, and on the other hand, the pure water supply nozzle on the front side of the wafer is retracted from the wafer, and pure water containing the micro-nano bubbles is supplied to a treatment cup connected to the waste liquid line and provided adjacent to the table.

[0015] [5] The pipe washing method of the single-wafer wafer washing apparatus according to any one of the preceding [1] to [4], characterized in that the pipe washing process is performed for the washing of one wafer at a time.

[0016] [6] The pipe washing method of the single-wafer wafer washing apparatus according to any one of the preceding [1] to [5], characterized in that the pipe washing process is performed simultaneously with the wafer drying process in a wafer washing method including a wafer washing process, a wafer rinsing process, and a wafer drying process, in the wafer washing process, the chemical liquid is sprayed onto the front and / or back side of the wafer to wash it, in the wafer rinsing process, pure water not containing the micro-nano bubbles is sprayed onto the front and / or back side of the wafer to rinse it, and in the wafer drying process, the wafer is rotated to dry it without supplying the chemical liquid and / or the pure water not containing the micro-nano bubbles to the front side of the wafer.

[0017] [7] The pipe washing method of the single-wafer wafer washing apparatus according to the preceding [6], characterized in that the pipe washing process has a first process and a second process, in the first process, pure water containing the micro-nano bubbles is supplied, and in the second process, pure water not containing the micro-nano bubbles is supplied after the first process.

[0018] [8] The pipe washing method of the single-wafer wafer washing apparatus according to any one of the preceding [1] to [4], characterized in that the pipe washing process is automatically performed at a predetermined washing treatment interval.

[0019] [9] The pipe washing method of the single-wafer wafer washing apparatus according to the preceding [8], characterized in that the predetermined washing treatment interval is automatically set based on an evaluation result of the number of particles on the wafer.

[0020]

[10] The pipe washing method of the single-wafer wafer washing apparatus according to the preceding [8], characterized in that the number of particles contained in the pure water passing through the pure water supply nozzle is monitored by means of a particle counter that counts particles in a liquid, and the predetermined washing treatment interval is set based on the number of particles monitored.

[0021] Effects of the Invention

[0022] According to the present invention, the number of particles detected on the surface of the wafer can be prevented from abruptly increasing even when the washing of the wafer is repeatedly performed using the single-wafer wafer washing apparatus. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a view showing an example of a general single-wafer wafer washing apparatus.

[0024] Figure 2 is a view showing a single-wafer wafer washing apparatus to which a micro-nano bubble generating apparatus is connected. Figure 1 is a view showing a pure water supply line of the single-wafer wafer washing apparatus shown in

[0025] Figure 3 is a view showing an example of a pipe washing method of the single-wafer wafer washing apparatus of the present invention, (a) is a side view, and (b) is a plan view.

[0026] Figure 4 is a view showing another example of the pipe washing method of the single-wafer wafer washing apparatus of the present invention.

[0027] Figure 5 is a flowchart showing a general wafer washing method using a single-wafer wafer washing apparatus to which the pipe washing process of the present invention is added.

[0028] Figure 6 is a view showing the variation in the number of particles on a silicon wafer when the washing of the silicon wafer is continuously performed, (a) is a view regarding a conventional example, and (b) is a view regarding an inventive example. DETAILED DESCRIPTION

[0029] An embodiment of the present application will be described below with reference to the accompanying drawings. The present application is a method of washing piping of a single-wafer type wafer cleaning apparatus, the single-wafer type wafer cleaning apparatus including a table on which a wafer is placed and which is rotatable, a chemical liquid supply nozzle that supplies a chemical liquid to the wafer placed on the table from a front side and / or a back side of the wafer, a pure water supply nozzle that supplies pure water to the wafer placed on the table from the front side and / or the back side of the wafer, a chemical liquid supply line that supplies the chemical liquid to the chemical liquid supply nozzle, a pure water supply line that supplies the pure water to the pure water supply nozzle, and a waste liquid line that discharges the supplied chemical liquid and pure water. The present application is characterized by including a piping washing step of washing piping of the pure water supply line by introducing pure water containing micro-nano bubbles into the pure water supply line.

[0030] As described above, when the wafer W is repeatedly cleaned by the single-wafer type wafer cleaning apparatus, the number of particles detected on the surface of the wafer W suddenly increases, and the present inventors have conducted intensive studies on the cause thereof. As a result, it is considered that particles accumulated in the piping of the pure water supply line 15 are discharged when the wafer W is supplied with pure water in the wafer rinsing step, and adhere to the surface of the wafer W.

[0031] That is, the pure water used in the wafer rinsing step of the cleaning step is branched from the main pure water supply line of the factory to each cleaning apparatus, but at this time, the metal and particles are removed by the filter. However, in the removal by the filter as described above, the particles are not sufficiently removed depending on the opening diameter of the filter and the like. In addition, the piping of the pure water supply line 15 is supplied with pure water for a short period of time when new, the piping is cleaned, the quality of the pure water circulating inside is checked, and the piping is used at a stage where the established criteria are satisfied, but after that, maintenance is not performed in many cases. Therefore, particles are accumulated in the joints and valves of the piping of the pure water supply line 15 of each cleaning apparatus, suddenly flow out in the wafer rinsing step, are supplied to the surface of the wafer W, and have the possibility of adhering to the wafer W.

[0032] Based on the above-described assumption, the present inventors have conducted intensive studies on a method of removing particles adhering inside the piping of the pure water supply line 15. As a method of removing the particles, it is considered that the flushing of continuously supplying pure water to the pure water supply line 15 is effective, but requires a large amount of time, and in addition, there is a possibility that the particles accumulated at the joints and valves cannot be sufficiently removed. Therefore, the present inventors have conducted intensive studies on a method other than the flushing, and as a result, it is conceived to supply pure water containing micro-nano bubbles (hereinafter, also referred to as "water containing micro-nano bubbles") to clean the inside of the piping of the pure water supply line 15.

[0033] Water containing micro-nano bubbles is water containing fine bubbles of micro size and nano size, and in recent years, has been used as washing water for removing adherents adhering to the surface of a washing object. For example, in Japanese Patent Application Publication No. 2013-248582, it is used as washing water for washing electronic materials such as wafers.

[0034] However, when water containing micro-nano bubbles introduced into the pure water supply line 15 is supplied from the pure water supply nozzle 13 to the surface of the wafer W in the wafer rinsing process, there is a possibility that the particles in the pipe of the pure water supply line 15 removed by the micro-nano bubbles adhere to the surface of the wafer W. Therefore, the present inventors found that, by introducing water containing micro-nano bubbles into the pure water supply line 15 and supplying it to other than the wafer W, particles can be removed efficiently in a short time, and the sudden increase of particles can be suppressed, and completed the present application. Here, regarding "supplying water containing micro-nano bubbles to other than the wafer W", it will be described in detail later, but for example, water containing micro-nano bubbles is supplied directly to the waste liquid line 17 without contacting the surface of the wafer W, the upper nozzle 13a of the pure water supply nozzle 13 is retracted from the wafer W and water containing micro-nano bubbles is supplied to the upper nozzle 13a, and is supplied to a treatment cup directly communicating with the waste liquid line 17, and the like.

[0035] In the present application, the diameter of the micro-nano bubbles of water containing micro-nano bubbles is preferably 0.1 μm or more and 10 μm or less. By making the diameter of the micro-nano bubbles in the above range, particles adhering to the surface of the wafer W can be removed efficiently.

[0036] Further, the density of the micro-nano bubbles is preferably 1 x 10 5 particles / cm 3 or more and 1 x 10 10 particles / cm 3 or less. By making the density of the micro-nano bubbles 1 x 10 5 particles / cm 3 or more, the washing effect inside the pipe of the pure water supply line 15 can be improved. Further, the upper limit of the density of the micro-nano bubbles is not limited in terms of the washing effect, but it is difficult to form micro-nano bubbles at a density exceeding 1 x 10 10 particles / cm 3 , so the density is preferably 1 x 10 10 particles / cm 3 or more.

[0037] The flow rate of water containing micro-nano bubbles is preferably between 0.5 L / min and 2.0 L / min. By ensuring the flow rate of water containing micro-nano bubbles is 0.5 L / min or higher, the washing effect inside the piping of the pure water supply line 15 can be improved. Furthermore, even if the flow rate of water containing micro-nano bubbles exceeds 2.0 L / min, the washing effect remains unchanged, so the flow rate of water containing micro-nano bubbles is preferably below 2.0 L / min.

[0038] The introduction time of water containing micro-nano bubbles is set to be longer than the time required for the water in the pure water supply nozzle 13 to be replaced, but shorter than the time required to avoid affecting the productivity of wafer W. Specifically, the introduction time of water containing micro-nano bubbles is preferably 10 seconds to 30 seconds. By making the introduction time of water containing micro-nano bubbles 10 seconds or more, the washing effect inside the piping of the pure water supply line 15 can be improved. Furthermore, even if the introduction time of water containing micro-nano bubbles exceeds 30 seconds, the washing effect remains unchanged, so the introduction time of water containing micro-nano bubbles is preferably 30 seconds or less.

[0039] The purity of pure water containing micro-nano bubbles is not particularly limited as long as it is sufficient to achieve product quality. It can also be set as the purity level of so-called pure water (e.g., resistivity: 0.1 to 15 MΩ·cm) or ultrapure water (e.g., resistivity: over 15 MΩ·cm).

[0040] like Figure 2 As shown, the pure water supply line 15 is connected to the micro-nano bubble generator 18, so that the pure water in the pure water supply line 15 is mixed with the micro-nano bubbles generated by the micro-nano bubble generator 18, thereby generating the water containing micro-nano bubbles.

[0041] Water containing micro-nano bubbles, generated as described above, is introduced into the pure water supply line 15, thereby washing the piping of the pure water supply line 15 and removing particles attached to the inside of the piping.

[0042] Regarding the location where the water containing micro-nano bubbles is introduced, the timing of the wafer rinsing process in each monolithic wafer washing apparatus 100 differs. Therefore, when the water containing micro-nano bubbles is introduced from the pure water supply line 15 at a position upstream of the branching point of each monolithic wafer washing apparatus, there is a possibility of supplying the water containing micro-nano bubbles to the wafer W. Therefore, it is preferable to introduce the water containing micro-nano bubbles at the pure water supply line 15 of each washing apparatus (i.e., at a position downstream of the aforementioned branching point).

[0043] On the other hand, regarding the location of the water containing micro-nano bubbles, the pure water supply line 15 is connected to the pure water supply nozzle 13, so the water containing micro-nano bubbles introduced into the pure water supply line 15 is sprayed from the pure water supply nozzle 13. At this time, when the wafer W is placed on the stage 11 and the water containing micro-nano bubbles is sprayed onto the wafer W, there is a possibility that particles removed by the water containing micro-nano bubbles may adhere to the surface of the wafer W.

[0044] In typical single-wafer washing equipment, such as Figure 3 As schematically shown in (a) and (b), the processing cup 19, which receives the liquid medicine and pure water falling from the upper nozzles 12a and 13a of the liquid medicine supply nozzle 12 and the pure water supply nozzle 13 respectively, is configured such that when these nozzles retract from the wafer W, the liquid medicine and pure water collected by the processing cup 19 do not come into contact with the wafer W. Furthermore, a discharge port communicating with the waste liquid line 17 is provided at the bottom of the processing cup 19, configured such that the liquid medicine and pure water collected by the processing cup 19 are discharged into the waste liquid line 17. The processing cup 19 is configured to be adjacent to the stage 11 within the range where the upper nozzles 12a and 13a can retract, for example, adjacent to the outside of the rotating cup 16. Therefore, as... Figure 3 As shown in (b), with the upper nozzle 13a of the pure water supply nozzle 13 rotating radially along the wafer W and retracting from the wafer W, water containing micro-nano bubbles is introduced into the pure water supply line 15. The washed pure water is then discharged from the spray port 13c of the upper nozzle 13a into the processing cup 19. This allows the water containing micro-nano bubbles to be discharged to the waste liquid line without contacting the wafer surface. Consequently, the inside of the pure water supply line 15 piping can be washed without particles removed from inside the piping adhering to the surface of the wafer W. Furthermore, the structure of the processing cup 19 is not limited to the above structure; it can be configured to discharge the water containing micro-nano bubbles received from the upper nozzle 13a to the waste liquid line 17 without contacting the wafer W.

[0045] In addition, such as Figure 4 The diagram schematically illustrates that a three-way valve 20 is installed at the pure water supply line 15. One of the two outlets is connected to the pure water supply nozzle 13, and the other outlet is connected to the waste liquid line 17. When the outlet of the three-way valve 20 is switched to the waste liquid line 17, water containing micro-nano bubbles is introduced into the pure water supply line 15. This allows the water containing micro-nano bubbles to be discharged into the waste liquid line 17 without contacting the surface of the wafer W. Therefore, the inside of the pure water supply line 15 piping can be cleaned without particles removed from the piping of the pure water supply line 15 adhering to the surface of the wafer W.

[0046] Further, a three-way valve 20 is provided between the lower nozzle 13b, which is a pure water supply nozzle on the back side of the wafer, and the pure water supply line 15, and one of the two outlets of the three-way valve 20 is connected to the lower nozzle 13b and the other is connected to the waste line 17. In the pipe washing process, the outlet of the three-way valve 20 is switched to the waste line 17 side, and the water containing micro- and nano-bubbles is introduced into the pure water supply line 15. On the other hand, the upper nozzle 13a, which is a pure water supply nozzle on the front side of the wafer, is retracted from the wafer W, and the water containing micro- and nano-bubbles can be supplied to the treatment cup 19 connected to the waste line 17, which is provided adjacent to the table 11.

[0047] The above pipe washing process is preferably performed for the washing treatment of one wafer W at a time. Thus, the sudden increase in the particles adhering to the wafer W can be prevented.

[0048] However, the pipe washing process is not necessarily performed for the washing treatment of one wafer W at a time, and can be configured to be automatically performed at a predetermined washing treatment interval. The predetermined washing treatment interval can be set to an interval shorter than the above interval of the sudden increase, for example, by grasping the interval of the sudden increase in the particles in advance. Further, the predetermined washing treatment interval can be configured to be automatically set based on the evaluation result of the number of particles on the wafer W in the quality inspection process. Furthermore, the predetermined washing treatment interval can be configured to be set based on the number of particles monitored in the pure water supplied through the pure water supply nozzle 13 by means of a particle counter that counts the particles in the liquid. The monitoring of the particles contained in the above pure water is preferably performed before the wafer washing treatment, when the pipe inside the pure water supply line 15 is replaced with pure water by supplying the pure water not containing micro- and nano-bubbles to the pure water supply line 15 after the water containing micro- and nano-bubbles is ejected, and when the pure water not containing micro- and nano-bubbles is virtually dispensed.

[0049] Further, the pipe washing process of the present application can be appropriately combined with the conventional wafer washing method (i.e., the washing process in the wafer manufacturing process). Figure 5 A flowchart showing a general wafer washing method using a single-wafer type wafer washing apparatus to which the pipe washing process of the present application is added is shown in FIG. 6. As shown in FIG. 6, the general wafer washing method includes a wafer washing process and a quality inspection process. Figure 5As shown, the general wafer washing method using a single wafer wafer includes a wafer washing step SI in which a chemical solution is sprayed to the front and / or back surface of the wafer to wash the wafer, a wafer rinsing step S2 in which pure water not containing micro-nano bubbles is sprayed to the front and / or back surface of the wafer to rinse the wafer, and a wafer drying step S3 in which the wafer is rotated without spraying a chemical solution and / or pure water not containing micro-nano bubbles to the surface of the wafer to dry the wafer. The pipe washing step S4 of the present application is performed simultaneously with the wafer drying step S3 in the above wafer washing method, whereby the washing of the wafer W and the washing of the pipe of the single wafer wafer washing apparatus can be performed simultaneously without the particles removed from the pipe by the water containing micro-nano bubbles being attached to the wafer W, and thus is preferable. In addition, the "pure water not containing micro-nano bubbles" means pure water not containing micro-nano bubbles substantially without mixing micro-nano bubbles by means of a micro-nano bubble generating apparatus.

[0050] As described above, preferably, when the pipe washing step of the present application is combined with the steps of the wafer washing method, the step of supplying pure water containing micro-nano bubbles (1st step) is followed by the step of switching to the supply of pure water not containing micro-nano bubbles (2nd step). Thereby, the remaining portion of the water containing micro-nano bubbles can be prevented from being supplied to the wafer W.

[0051] Example

[0052] Hereinafter, the embodiments of the present application will be described, but the present application is not limited by the embodiments.

[0053] (Conventional Example)

[0054] By using Figure 1 The single wafer wafer washing apparatus 100 represented in FIG. 1 washed 900 silicon wafers continuously. Specifically, the silicon wafers as the objects to be washed were introduced to the single wafer wafer washing apparatus 100 to be placed on the stage 11. Next, while rotating the stage 11, 1% hydrofluoric acid aqueous solution and ozone water were alternately sprayed repeatedly from the chemical solution supply nozzle 12 to wash the front and back surfaces of the silicon wafers (wafer washing step). Next, pure water was supplied from the pure water supply line 15 to rinse the front and back surfaces of the silicon wafers (wafer rinsing step). After that, the silicon wafers were rotated at high speed to dry the silicon wafers (wafer drying step). Next, the particles attached to the surface of the silicon wafers after the washing were detected as light point defects (LPD) by using a surface inspection apparatus (Surfscan SP2 manufactured by KLA-Tencor Corporation). At this time, the detection mode was set to the DCO (Darkfield Composite Oblique) mode, and the number of LPDs having a size of 45 nm or more was counted. The obtained results are represented in (a) of FIG. 1. Figure 6 As described above, preferably, when the pipe washing step of the present application is combined with the steps of the wafer washing method, the step of supplying pure water containing micro-nano bubbles (1st step) is followed by the step of switching to the supply of pure water not containing micro-nano bubbles (2nd step). Thereby, the remaining portion of the water containing micro-nano bubbles can be prevented from being supplied to the wafer W.

[0055] (Inventive Example)

[0056] 900 silicon wafers were continuously washed as in the conventional example. However, the washing of the silicon wafers was performed using the single-wafer wafer washing apparatus 100 shown in Figure 2 At this time, as shown in Figure 5 , the washing of the piping of the pure water supply line 15 (piping washing process) was performed simultaneously with the wafer drying process. The piping washing process was specifically that a micro-nano bubble generator of a form capable of being applied to pure water was connected to the pure water supply line 15 by modifying a general foam device, and water containing micro-nano bubbles was supplied to the pure water supply line 15. The other conditions were completely the same as in the conventional example. The number of LPDs detected is shown in Figure 6 (b).

[0057] As shown in Figure 6 (a), in the conventional example, the number of LPDs, that is, the number of particles, increased suddenly at a frequency of about 1 in 600 silicon wafers. In contrast, as shown in Figure 6 (b), in the inventive example, it was found that the number of particles did not suddenly increase even when 900 silicon wafers were continuously washed.

[0058] Industrial applicability

[0059] According to the present application, even when the washing of the wafer W is repeatedly performed using the single-wafer wafer washing apparatus, the sudden increase in the number of particles detected at the surface of the wafer can be suppressed, and thus the present application is useful in the semiconductor industry.

[0060] Explanation of Reference Numerals

[0061] 11 table

[0062] 11a wafer holding portion

[0063] 12 chemical liquid supply nozzle

[0064] 12a, 13a upper nozzle

[0065] 12b, 13b lower nozzle

[0066] 13 pure water supply nozzle

[0067] 13c jet port

[0068] 14 chemical liquid supply line

[0069] 15 pure water supply line

[0070] 16 rotating cup

[0071] 17 waste liquid line

[0072] 18 micro-nano bubble generating device

[0073] 19 process cup

[0074] 20 tee valve

[0075] 100 single wafer cleaning apparatus

[0076] W wafer

Claims

1. A method of washing piping of a single-wafer cleaning apparatus, the method of washing piping of a single-wafer cleaning apparatus, the single-wafer cleaning apparatus having a stage, a chemical liquid supply nozzle, a pure water supply nozzle, a chemical liquid supply line, a pure water supply line, a waste liquid line, the stage on which a wafer is placed and is rotatable, the chemical liquid supply nozzle which supplies a chemical liquid to the wafer placed on the stage from a front side and / or a back side of the wafer, the pure water supply nozzle which supplies pure water to the wafer placed on the stage from the front side and / or the back side of the wafer, the chemical liquid supply line which supplies the chemical liquid to the chemical liquid supply nozzle, the pure water supply line which supplies the pure water to the pure water supply nozzle, the waste liquid line which discharges the chemical liquid and the pure water supplied, the method of washing piping of a single-wafer cleaning apparatus being characterized in that, in the piping washing step, the pure water containing micro-nano bubbles is supplied to a place other than the wafer without contacting a surface of the wafer.

2. The method of washing piping of a single-wafer cleaning apparatus according to claim 1, characterized in that, a three-way valve is provided at the pure water supply line, one of two outlets is connected to the pure water supply nozzle, the other is connected to the waste liquid line, and in the piping washing step, the pure water containing the micro-nano bubbles is introduced to the pure water supply line in a state where the outlet of the three-way valve has been switched to the waste liquid line side.

3. The method of washing piping of a single-wafer cleaning apparatus according to claim 1, characterized in that, in the piping washing step, the pure water supply nozzle is retracted from the wafer, and the pure water containing the micro-nano bubbles is supplied to a treatment cup connected to the waste liquid line and provided adjacent to the stage.

4. The method of washing piping of a single-wafer cleaning apparatus according to claim 1, characterized in that, a three-way valve is provided between the pure water supply nozzle on the back side of the wafer and the pure water supply line, one of two outlets is connected to the pure water supply nozzle on the back side of the wafer, the other is connected to the waste liquid line, and in the piping washing step, the pure water containing the micro-nano bubbles is introduced to the pure water supply line in a state where the outlet of the three-way valve has been switched to the waste liquid line side, and on the other hand, the pure water supply nozzle on the front side of the wafer is retracted from the wafer, and the pure water containing the micro-nano bubbles is supplied to a treatment cup connected to the waste liquid line and provided adjacent to the stage.

5. The method of washing piping of a single-wafer cleaning apparatus according to any one of claims 1 to 4, characterized in that, the piping washing step is performed for washing treatment of one wafer at a time.

6. The method of washing piping of a single-wafer cleaning apparatus according to any one of claims 1 to 4, characterized in that, the piping washing step is performed simultaneously with the wafer drying step in a wafer cleaning method including a wafer cleaning step, a wafer rinsing step, and the wafer drying step, and in the wafer cleaning step, the chemical liquid is sprayed to the front side and / or the back side of the wafer to clean. ​ ​ This includes introducing a substance with a density of 1×10 into the aforementioned pure water supply line. 5 pcs / cm 3 Above 1×10 10 pcs / cm 3 The following micro-nano bubble pure water is used to clean the piping of the aforementioned pure water supply line in a piping cleaning process. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In the wafer rinsing process, pure water not containing the aforementioned micro-nano bubbles is sprayed to the front surface and / or the back surface of the wafer to rinse the wafer. In the wafer drying process, the wafer is rotated without supplying the aforementioned chemical liquid to the front surface of the wafer and / or pure water not containing the aforementioned micro-nano bubbles to dry the wafer.

7. The single-wafer piping washing method according to claim 6, wherein the piping washing process is performed simultaneously with the wafer rinsing process. The piping washing process has a first process and a second process. In the first process, pure water containing the aforementioned micro-nano bubbles is supplied. In the second process, pure water not containing the aforementioned micro-nano bubbles is supplied after the first process.

8. The single-wafer piping washing method according to any one of claims 1 to 4, wherein the piping washing process is automatically performed at a predetermined washing interval.

9. The single-wafer piping washing method according to claim 8, wherein the predetermined washing interval is automatically set based on the evaluation result of the number of particles on the wafer.

10. The single-wafer piping washing method according to claim 8, wherein the predetermined washing interval is set based on the number of particles detected by a particle counter that counts particles in a liquid, the particle counter monitoring particles contained in the pure water that passes through the pure water supply nozzle.

11. The single-wafer piping washing method according to claim 5, wherein the piping washing process is performed simultaneously with the wafer rinsing process in the wafer washing method including a wafer washing process, a wafer rinsing process, and a wafer drying process, In the wafer washing process, the aforementioned chemical liquid is sprayed to the front surface and / or the back surface of the wafer to wash the wafer. In the wafer rinsing process, pure water not containing the aforementioned micro-nano bubbles is sprayed to the front surface and / or the back surface of the wafer to rinse the wafer. In the wafer drying process, the wafer is rotated without supplying the aforementioned chemical liquid to the front surface of the wafer and / or pure water not containing the aforementioned micro-nano bubbles to dry the wafer. ​ ​ ​ ​

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