Cleaning treatment method for workpiece and cleaning treatment system for workpiece

Abstract

In the workpiece cleaning method and system of the present invention, the diameter of the hole of the upper side straightening plate is smaller than the diameter of the hole of the lower side straightening plate. In the workpiece cleaning method of the present invention, the total area A (mm) of the plurality of holes of the lower side straightening plate is calculated. 2 ) and the sum of the areas of the multiple holes of the upper rectifier plate B (mm 2 ), determine the supply flow rate Q (L / min) of the cleaning liquid, or, based on the supply flow rate Q (L / min), determine the total area A (mm 2 ) and / or the sum of the areas B (mm 2 The workpiece cleaning system of the present invention further comprises: a calculation unit, which calculates the total area A (mm 2 ) and the sum of the area B(m 2 ), determine the supply flow rate Q (L / min) of the cleaning liquid; and the control unit controls to supply the cleaning liquid at the determined supply flow rate Q (L / min). The total area A (mm 2 ), the sum of the areas B (mm 2 ) and the determined supply flow rate Q (L / min), or the supply flow rate Q (L / min) and the sum of the determined areas A (mm 2 ) and / or the sum of the areas B (mm 2 ) satisfies the prescribed relationship.

Description

Technical Field

[0001] The present invention relates to a workpiece cleaning method and a workpiece cleaning system, in particular to cleaning of semiconductor wafers such as silicon wafers, and more particularly to a cleaning method and a cleaning system related to single-wafer immersion cleaning. Background Art

[0002] One cleaning method used in silicon wafer manufacturing is single-wafer immersion cleaning. In this immersion cleaning, wafers placed in a cleaning tank are immersed in a cleaning solution (e.g., ozone water) to oxidize and remove organic matter adhering to the wafers (in the case of ozone water, the wafer surface is further coated with an oxide film).

[0003] Generally, a cleaning liquid such as ozone water flows from the bottom of a cleaning tank, filling it, then overflows at the top, flows into a drainage channel surrounding the tank, and then flows out of the tank. For example, in a single-wafer cleaning process, as described above, wafers are transported one by one by a robotic arm within the cleaning tank where the cleaning liquid flows, and are fully cleaned one by one.

[0004] In this cleaning method, in order to improve the uniformity of cleaning within the surface of the wafer, the flow of the cleaning liquid in the cleaning tank is rectified in various ways. For example, Patent Document 1 discloses that a branch pipe with multiple holes is horizontally arranged at the bottom of the cleaning tank, and the cleaning liquid is discharged from the holes, and multiple rectifying plates with multiple holes are arranged between the wafer and the pipe. Also, for example, Patent Document 2 discloses that a buffer tank with an inlet for the cleaning liquid is arranged at the bottom of the cleaning tank, and multiple rectifying porous plates are arranged. The rectifying porous plates are provided with multiple flow holes through which the cleaning liquid circulates. Furthermore, Patent Document 2 discloses that the diameter of the flow holes is formed so that the rectifying porous plates arranged at the upper position are smaller.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 04-056321

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 09-232272 Summary of the Invention

[0009] Technical problem to be solved by the invention

[0010] When cleaning wafers, it's desirable to minimize the amount of cleaning fluid used per wafer, so the cleaning tank is preferably as small as possible. In particular, single-wafer cleaning requires many more cleaning tanks because throughput is lower than in batch cleaning. Therefore, it's particularly desirable to keep each tank as small as possible. Furthermore, large cleaning tanks make it difficult to control the flow of cleaning fluid and to remove particles from the tank. For this reason, a small cleaning tank is also preferred.

[0011] However, the method of Patent Document 1 mitigates the flow rate by arranging a tube horizontally and spraying the cleaning liquid from the holes below it toward the bottom of the cleaning tank. This requires space for the tube, which increases the size of the cleaning tank. Furthermore, in Patent Document 2, if the flow of the cleaning liquid reaches the rectifying perforated plate in an insufficiently moderated state, it is possible that a large amount of cleaning liquid will flow through some of the holes, preventing a sufficient rectification effect. This requires a large buffer tank to address this, which also increases the size of the cleaning tank. Furthermore, the aforementioned problem occurs not only when the cleaning object is a wafer, but also when the entire workpiece undergoes the same cleaning.

[0012] Therefore, an object of the present invention is to provide a workpiece cleaning method and a workpiece cleaning system, which do not make the cleaning tank larger than necessary and can rectify the flow of cleaning liquid in the cleaning tank.

[0013] Solutions for solving technical problems

[0014] The gist of the present invention is as follows.

[0015] (1) A method for cleaning a workpiece, comprising the following steps:

[0016] Preparation of cleaning tank process;

[0017] The step of placing a workpiece in the cleaning tank; and

[0018] a step of supplying a cleaning liquid into the cleaning tank from a cleaning liquid supply port provided at the bottom of the cleaning tank to clean the workpiece;

[0019] The cleaning method of the workpiece is characterized in that:

[0020] Two rectifying plates are arranged between the position where the workpiece is set and the bottom, the two rectifying plates being composed of an upper rectifying plate and a lower rectifying plate, and the lower rectifying plate is located closer to the bottom side of the cleaning tank than the upper rectifying plate;

[0021] The upper rectifying plate and the lower rectifying plate each have a plurality of holes;

[0022] The diameter of the hole of the upper rectifying plate is smaller than the diameter of the hole of the lower rectifying plate;

[0023] It also includes the sum of the areas A (mm) of the plurality of holes of the lower side rectifying plate. 2 ) and the sum of the areas of the plurality of holes of the upper rectifying plate B (mm 2 ) to determine the supply flow rate Q (L / min) of the cleaning liquid, in the process of supplying the cleaning liquid and cleaning the workpiece, the cleaning liquid is supplied at the determined supply flow rate Q (L / min), or the process further includes determining the total area A (mm2) according to the supply flow rate Q (L / min) 2 ) and / or the sum of the areas B (mm 2 ) process, in the process of preparing the cleaning tank, the cleaning tank is prepared with the lower side rectifying plate and / or the upper side rectifying plate, and the lower side rectifying plate includes the total area A (mm 2 ) of the plurality of holes, the upper side rectifying plate includes a total area B (mm 2 ) of the plurality of holes;

[0024] The sum of the areas A (mm 2 ), the sum of the areas B (mm 2 ) and the determined supply flow rate Q (L / min), or the supply flow rate Q (L / min) and the sum A (mm2) of the determined areas 2 ) and / or the sum of the areas B (mm 2 ) satisfies the following relation (a),

[0025] B / A≥5.6×10 -2 exp(0.46Q) and

[0026] B / A≤-6.9×10 -2 Q 2 +1.2Q+3.4.

[0027] (2) The workpiece cleaning method according to (1), wherein:

[0028] The sum of the areas A (mm 2 ), the sum of the areas B (mm 2 ) and the determined supply flow rate Q (L / min), or the supply flow rate Q (L / min) and the sum A (mm2) of the determined areas 2 ) and / or the sum of the areas B (mm 2) also satisfies the following relation (b),

[0029] B / A≥3.2×10 -2 Q 2 +0.36Q-0.47 and

[0030] B / A≤-5.1×10 -2 Q 2 +1.1Q+0.62.

[0031] (3) The workpiece cleaning method according to (1) or (2), wherein:

[0032] The distance between the two rectifier plates is greater than 10 mm.

[0033] (4) The workpiece cleaning method according to any one of (1) to (3), wherein:

[0034] The workpiece is a wafer, and when the wafer is placed in the cleaning tank, the horizontal cross-sectional area of the cleaning tank at a height including the center of the wafer is 9000 mm. 2 Above and 60000mm 2 the following.

[0035] (5) A workpiece cleaning system comprising a cleaning tank, characterized in that:

[0036] The cleaning tank is configured so that a workpiece can be placed in the cleaning tank;

[0037] A cleaning liquid supply port is provided at the bottom of the cleaning tank for supplying cleaning liquid into the cleaning tank;

[0038] Two rectifying plates are arranged between the position where the workpiece is placed and the bottom of the cleaning tank. The two rectifying plates are composed of an upper rectifying plate and a lower rectifying plate, and the lower rectifying plate is located closer to the bottom of the cleaning tank than the upper rectifying plate.

[0039] The upper rectifying plate and the lower rectifying plate each have a plurality of holes;

[0040] The diameter of the hole of the upper rectifying plate is smaller than the diameter of the hole of the lower rectifying plate;

[0041] The system further includes a calculation unit that calculates the area of the plurality of holes of the lower straightening plate based on the total area A (mm 2 ) and the sum of the areas of the plurality of holes of the upper rectifying plate B (mm 2 ), determining a supply flow rate Q (L / min) of the cleaning liquid; and a control unit, controlling the supply of the cleaning liquid at the determined supply flow rate Q (L / min);

[0042] The sum of the areas A (mm 2 ), the sum of the areas B (mm 2 ) and the supply flow rate Q (L / min) determined by the calculation unit satisfy the following relational expression (a),

[0043] B / A≥5.6×10 -2 exp(0.46Q) and

[0044] B / A≤-6.9×10 -2 Q 2 +1.2Q+3.4.

[0045] (6) The workpiece cleaning system according to (5) above, wherein:

[0046] The sum of the areas A (mm 2 ), the sum of the areas B (mm 2 ) and the supply flow rate Q (L / min) determined by the calculation unit also satisfy the following relational expression (b),

[0047] B / A≥3.2×10 -2 Q 2 +0.36Q-0.47 and

[0048] B / A≤-5.1×10 -2 Q 2 +1.1Q+0.62.

[0049] (7) The workpiece cleaning system according to (5) or (6), wherein:

[0050] The distance between the two rectifier plates is greater than 10 mm.

[0051] (8) The workpiece cleaning system according to any one of (5) to (7), wherein:

[0052] The workpiece is a wafer, and when the wafer is placed in the cleaning tank, the horizontal cross-sectional area of the cleaning tank at a height including the center of the wafer is 9000 mm. 2 Above and 60000mm 2 the following.

[0053] Effects of the Invention

[0054] According to the present invention, a workpiece cleaning method and a workpiece cleaning system can be provided, which do not make the cleaning tank larger than necessary and can rectify the flow of the cleaning liquid in the cleaning tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of a workpiece cleaning system according to one embodiment of the present invention.

[0056] Figure 2 This is a flowchart of a workpiece cleaning method according to one embodiment of the present invention.

[0057] Figure 3 This is a graph showing the relationship between the flow rate of the cleaning liquid, B / A, and the effect.

[0058] Figure 4 This is a diagram showing the relationship between the distance between the rectifying plates and the time required to discharge the particles. DETAILED DESCRIPTION

[0059] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0060] <Workpiece cleaning system>

[0061] First, a workpiece cleaning system according to an embodiment of the present invention will be described. The embodiment of the workpiece cleaning method described below can be performed using this workpiece cleaning system, for example.

[0062] Figure 1 FIG is a schematic diagram of a workpiece cleaning system according to an embodiment of the present invention. Figure 1 As shown, a workpiece cleaning system 1 according to the present embodiment includes a cleaning tank 2 , a calculation unit 6 , and a control unit 7 .

[0063] The cleaning tank 2 is configured so that a workpiece W can be set in the cleaning tank 2. The workpiece W becomes the object of the cleaning process, and as an example, can be a semiconductor wafer such as a silicon wafer. In this example, the workpiece W is a silicon wafer. The cleaning tank 2 shown in the figure is a single-chip wafer cleaning tank configured to accommodate one wafer, and can be suitably used for immersion. The diameter of the workpiece W is not particularly limited. When the workpiece W is a wafer, it can be, for example, 200 mm, 300 mm, or 450 mm. The cleaning tank 2 is preferably relatively small within a range corresponding to the size of the workpiece W (a workpiece W of a specified size can be set). Specifically, when the workpiece W is a wafer, when the wafer is set in the cleaning tank 2, the horizontal cross-sectional area of the cleaning tank 2 at the height including the center of the wafer is preferably 9000 mm. 2 Above and 60000mm 2 If the horizontal cross-sectional area is 9000mm 2 For example, if the horizontal cross-sectional area is 60000mm, the wafer with a diameter of 450mm can be accommodated. 2The amount of cleaning fluid used can be reduced. The cleaning tank 2 is not particularly limited, but can be made of, for example, quartz glass. The workpiece W is supported by a rack (not shown) so that the surface of the workpiece W is perpendicular to the horizontal direction. The workpiece W is transported and placed into the cleaning tank 2 by, for example, a robotic arm (not shown). This robotic arm can also be used to remove the cleaned workpiece W from the cleaning tank.

[0064] like Figure 1 As shown, at the bottom of the cleaning tank 2, there are provided cleaning liquid supply ports (nozzles) 3 (two in this example) for supplying cleaning liquid into the cleaning tank 2. The number of cleaning liquid supply ports 3 is not particularly limited, and may be one or more than three. In order to ensure uniform flow of the cleaning liquid in the cleaning tank 2, the cleaning liquid supply ports 3 are preferably arranged symmetrically with respect to the workpiece W. For example, as shown in the figure, when observing the surface of the wafer from the front, the cleaning liquid supply ports 3 can be arranged equidistantly at a position slightly below the center of the wafer.

[0065] And, as Figure 1As shown, two straightening plates are arranged between the position where the workpiece W is placed and the bottom of the cleaning tank 2. The two straightening plates are composed of an upper straightening plate 4 and a lower straightening plate 5, with the lower straightening plate 5 being located closer to the bottom of the cleaning tank 2 than the upper straightening plate 4. As shown in the figure, the two straightening plates are arranged so that the upper and lower surfaces are horizontal. The upper straightening plate 4 and the lower straightening plate 5 respectively have multiple holes 4a and 5a through which the cleaning liquid can pass. The holes are arranged in a grid pattern, with the holes arranged at equal intervals in a row (without special restrictions, for example, a spacing of 5mm to 20mm), and they are arranged in multiple columns (in the row direction). For example, the holes can be arranged so that the odd and even columns overlap when projected in the row direction, or the odd and even columns can be arranged in a staggered manner so that they are staggered by half the spacing in the row direction when projected in the row direction. The multiple holes provided in the upper straightening plate 4 are preferably of equal size, and the multiple holes provided in the lower straightening plate 5 are preferably of equal size. In this embodiment, the diameter of the holes in the upper straightening plate 4 is smaller than that of the holes in the lower straightening plate 5. Furthermore, if the diameters of the holes in the upper straightening plate 4 and / or the diameters of the holes in the lower straightening plate 5 are not equal, the average diameter of the holes in each straightening plate can be taken to be smaller than that of the holes in the lower straightening plate 5. While not particularly limited, the diameter of the holes in the lower straightening plate 5 can be 2 to 7 mm, and the diameter of the holes in the upper straightening plate 4 can be 1 to 5 mm, within a smaller range than the diameter of the holes in the lower straightening plate 5. The distance (shortest distance) between the two straightening plates 4 and 5 is preferably at least 10 mm. The larger the distance between the two straightening plates 4 and 5, the larger the area that acts as a buffer to reduce the flow velocity after the cleaning liquid passes through the lower straightening plate 5. To achieve a more uniform flow, the distance is preferably 10 mm or greater. On the other hand, considering that a large cleaning tank 2 is not required, or that the buffer effect gradually saturates with increasing distance, the distance is preferably 40 mm or less.

[0066] In this example, ozone water is used as the cleaning liquid, which not only removes particles but also forms an oxide film on the surface of the wafer. As other examples of the cleaning liquid, liquids containing any cleaning agent components or pure water can also be used.

[0067] Here, when cleaning liquid is supplied from cleaning liquid supply port 3 to cleaning tank 2 using a pump or the like, the cleaning liquid passes through multiple holes 5a in lower rectifying plate 5, then through multiple holes 4a in upper rectifying plate 4, flows to the upper portion of cleaning tank 2, and is recovered by an overflow tank provided therein. The recovered cleaning liquid is then filtered or otherwise treated before being supplied again from cleaning liquid supply port 3 to cleaning tank 2 using a pump or the like.

[0068] The calculation unit 6 calculates the area of the plurality of holes 5a of the lower straightening plate 5 based on the total area A (mm 2 ) and the sum of the areas B (mm) of the plurality of holes 4a of the upper rectifying plate 4 2 ), determine the supply flow rate Q (L / min) of the cleaning liquid. The calculation unit 6 can use any known calculator. In the present embodiment, the calculation unit 6 determines the supply flow rate Q of the cleaning liquid based on B / A. More specifically, according to the relationship (a) (preferably, also according to the relationship (b)), the supply flow rate Q of the cleaning liquid is determined in a manner that satisfies the relationship. In this example, the method for determining the supply flow rate within the range that satisfies the relationship (a) (preferably the relationship (b)) is arbitrary. For example, in order to minimize the amount of cleaning liquid, the minimum value within the range and its vicinity can be used, and in order to shorten the cleaning time, the maximum value within the range and its vicinity can be used. Alternatively, in order to more reliably satisfy the above-mentioned relationship (a) (preferably also the relationship (b)) when the supply flow rate is uneven, the supply flow rate corresponding to the center of gravity position of the area and its vicinity when the horizontal axis is regarded as B / A and the vertical axis is regarded as Q.

[0069] The control unit 7 controls the supply of cleaning liquid at a predetermined supply flow rate Q (L / min). Specifically, as an example, the supply flow rate can be controlled to the predetermined supply flow rate Q by opening and closing a valve of the cleaning liquid supply port 3 to adjust the size of the flow path. The control unit 7 can include any known processor.

[0070] As will be shown in the embodiment described later, the total area A (mm) of the plurality of holes 5a of the lower straightening plate 5 is 2 ), the total area B (mm) of the plurality of holes 4a of the upper rectifying plate 4 2 ), and the supply flow rate Q (L / min) determined by the calculation unit 6 satisfies the following relational expression (a),

[0071] B / A≥5.6×10 -2 exp(0.46Q) and

[0072] B / A≤-6.9×10 -2 Q 2 +1.2Q+3.4.

[0073] Preferably, the total area A (mm2) of the plurality of holes 5a of the lower rectifying plate 5 is 2 ), the total area B (mm) of the plurality of holes 4a of the upper rectifying plate 4 2 ), and the supply flow rate Q (L / min) determined by the calculation unit 6 also satisfies the following relational expression (b),

[0074] B / A≥3.2×10 -2 Q 2 +0.36Q-0.47 and

[0075] B / A≤-5.1×10 -2 Q 2 +1.1Q+0.62.

[0076] Hereinafter, the effects of the workpiece cleaning system according to the present embodiment will be described.

[0077] First, in the workpiece cleaning system of this embodiment, the diameter of the holes 4a in the upper straightening plate 4 is smaller than the diameter of the holes 5a in the lower straightening plate 5. Consequently, the cleaning liquid that has passed through the holes 5a in the lower straightening plate 5 cannot flow directly through the holes 4a in the upper straightening plate 4 slightly above it, but instead flows toward other holes 4a and along the upper straightening plate 4. This reduces flow bias between the holes. Furthermore, if the diameter of the holes 4a in the upper straightening plate 4 is larger than or equal to the diameter of the holes 5a in the lower straightening plate 5, a sufficient straightening effect cannot be achieved even if the aforementioned equation (a) (or (a) and (b)) are satisfied.

[0078] Here, the present inventors have found that the relative relationship between the total area A and the total area B affects the flow-regulating effect and that the relative relationship also depends on the supply flow rate Q, as shown below.

[0079] Specifically, if the total area B is excessively greater than the total area A (e.g., if B / A is excessively large), the pressure applied to the holes 5a of the lower straightening plate 5 becomes excessively high (relative to the upper straightening plate), causing the flow of the cleaning fluid to become more biased when reaching the upper straightening plate 4. Furthermore, since no differential pressure is generated across the upper straightening plate 4, the flow straightening effect is reduced. On the other hand, if the total area B is excessively less than the total area A (e.g., if B / A is excessively small), the flow straightening at the lower straightening plate 5 becomes insufficient, and since the pressure acting on the holes of the upper straightening plate 4 is excessively high, the flow of the cleaning fluid after passing through the lower straightening plate 5 becomes biased, reducing the flow straightening effect.

[0080] Furthermore, as the supply flow rate Q increases, the difference in the relative relationship between the sum of the areas A and B required to achieve the desired flow straightening effect increases (for example, the value of B / A increases). This is because a high supply flow rate Q increases the skewness of the flow velocity through the straightening plates. To reduce this skewness, it is necessary to reduce the sum of the areas A of the holes 5a in the lower straightening plates 5, making it difficult for the cleaning liquid to pass through the holes 5a. Furthermore, the force of the cleaning liquid ejected from the cleaning liquid supply port 3 must be reduced before it passes through the lower straightening plates 5. Furthermore, a high supply flow rate Q increases the pressure acting on the upper straightening plates 4, causing the flow velocity of the cleaning liquid passing through the holes 4a in the upper straightening plates 4 to become excessively high, resulting in a greater skewness in the flow of the cleaning liquid after passing through. Therefore, it is necessary to relatively increase the sum of the areas B of the holes in the upper straightening plates 4 and reduce the pressure acting on the upper straightening plates 4 to reduce the skewness in the flow velocity of the cleaning liquid.

[0081] Based on these circumstances, as well as those shown in the embodiments described below, the present inventors have come to the conclusion that satisfying the aforementioned equation (a) (preferably also satisfying the aforementioned equation (b)) effectively achieves the desired effect. Specifically, the velocity of the cleaning liquid supplied from the cleaning liquid supply port 3 can be reduced at the lower straightening plate 5, and the flow bias can be reduced before the cleaning liquid reaches the upper straightening plate 4. Furthermore, by generating a pressure differential across the upper straightening plate 4, the cleaning liquid can pass uniformly through each of the holes 4a in the upper straightening plate 4, resulting in a uniform upward flow of the cleaning liquid after passing through the upper straightening plate 4. This uniform upward flow allows particles flowing within the cleaning tank 2 to be rapidly discharged.

[0082] According to this method, the calculation unit 6 calculates the total area A (mm 2 ) and the sum of the area B(mm 2 ), determine the supply flow rate Q (L / min) of the cleaning liquid, and control the cleaning liquid to be supplied at the supply flow rate Q (L / min) determined by the calculation unit 6 through the control unit 7, because the total area A (mm 2 ), the sum of the areas B (mm 2 ) and the determined supply flow rate Q (L / min) satisfy the above-mentioned relationship (a), so the cleaning liquid can be effectively rectified.

[0083] As described above, according to the workpiece cleaning system of this embodiment, the flow of the cleaning liquid in the cleaning tank can be rectified without increasing the size of the cleaning tank beyond necessity.

[0084] Here, in the workpiece cleaning system of the present invention, the total area A (mm 2 ), the sum of the areas B (mm 2) and the determined supply flow rate Q (L / min) preferably also satisfy the above-mentioned relational expression (b). As also shown in the embodiment described later, this is because the flow of the cleaning liquid in the cleaning tank can be rectified more evenly.

[0085] Furthermore, in the workpiece cleaning system of the present invention, the distance between the two straightening plates 4 and 5 is preferably at least 10 mm. This is because after the cleaning liquid passes through the lower straightening plate 5, a larger area is ensured to act as a buffer to reduce the flow rate, thereby ensuring a more uniform flow. Furthermore, the distance (the shortest distance) between the bottom of the cleaning tank 2 and the lower straightening plate 5 is also preferably at least 10 mm. This is because before the cleaning liquid is supplied from the cleaning liquid supply port 3 and reaches the lower straightening plate 5, a larger area is ensured to act as a buffer to reduce the flow rate, thereby ensuring a more uniform flow.

[0086] Furthermore, in the workpiece cleaning system of the present invention, the workpiece is a wafer, and when the wafer is placed in the cleaning tank 2, the horizontal cross-sectional area of the cleaning tank 2 at a height including the center of the wafer is preferably 9000 mm. 2 Above and 60000mm 2 If the horizontal cross-sectional area is 9000mm 2 If the above-mentioned horizontal cross-sectional area is 60000mm, for example, a wafer with a diameter of 450mm can be accommodated. 2 The amount of cleaning fluid used can be reduced. Furthermore, in a cleaning tank 2 of this size range, if the diameter of the holes 4a of the upper rectifying plate 4 is made smaller than the diameter of the holes 5a of the lower rectifying plate 5 and the above-mentioned relationship (a) (preferably the above-mentioned relationship (b)) is satisfied, a better rectifying effect can be obtained.

[0087] <Workpiece Cleaning Method>

[0088] Next, a workpiece cleaning method according to an embodiment of the present invention will be described.

[0089] Figure 2 FIG. 1 is a flow chart of a method for cleaning a workpiece according to an embodiment of the present invention. Figure 2 As shown, in this embodiment, first, the cleaning tank 2 is prepared (step S101). Since the cleaning tank 2 or the components of the cleaning tank 2 are the same as those described above for the workpiece cleaning system, description thereof will be omitted.

[0090] Next, the workpiece W is placed in the cleaning tank 2 (step S102). As described above, the workpiece W can be placed in the cleaning tank by, for example, supporting the workpiece W with its surface perpendicular to the horizontal direction by a rack (not shown). The workpiece W can be transported into the cleaning tank 2 and placed therein by, for example, a robot arm (not shown).

[0091] Then, according to the total area A (mm) of the plurality of holes 5a of the lower side rectifying plate 5, 2 ) and the sum of the areas B (mm) of the plurality of holes 4a of the upper rectifying plate 4 2 ), determine the supply flow rate Q (L / min) of the cleaning liquid (step S103). This determination can be performed, for example, by the above-mentioned calculation unit 6 as described above. In addition, step S103 can also be performed before step S101 or step S102.

[0092] Next, cleaning liquid is supplied into the cleaning tank 2 from the cleaning liquid supply port 3 provided at the bottom of the cleaning tank 2 to clean the workpiece W (step S104). The cleaning liquid used is as described above. Here, the cleaning liquid is supplied at the supply flow rate Q (L / min) determined in step S103.

[0093] Next, the cleaning process is completed and the workpiece W is removed from the cleaning tank (step S105). The removal can be performed using the above-mentioned robot arm, etc. Then, for the next workpiece W, by repeating step S102 (step S106), the workpiece W can be cleaned piece by piece.

[0094] Hereinafter, the effects of the workpiece cleaning method according to the present embodiment will be described.

[0095] In the workpiece cleaning method of this embodiment, since the diameter of the holes 4a of the upper straightening plate 4 is smaller than the diameter of the holes 5a of the lower straightening plate 5, the flow bias between the holes of the upper straightening plate 4 can be reduced in the same manner as described above.

[0096] And, in step S103, according to the sum of the areas A (mm 2 ) and the sum of the area B(mm 2 ), determine the supply flow rate Q (L / min) of the cleaning liquid, and in step S104, supply the cleaning liquid at the supply flow rate Q (L / min) determined in step S103 to clean the workpiece W. Since the total area A (mm 2 ), the sum of the areas B (mm 2 ) and the determined supply flow rate Q (L / min) satisfy the above-mentioned relationship (a), so the system is the same as the above-mentioned one, and the cleaning fluid can be effectively rectified.

[0097] As described above, according to the workpiece cleaning method of this embodiment, the flow of the cleaning liquid in the cleaning tank can be rectified without increasing the size of the cleaning tank more than necessary.

[0098] In the workpiece cleaning method of the present invention, the total area A (mm 2 ), the sum of the areas B (mm 2 ) and the determined supply flow rate Q (L / min), or the supply flow rate Q (L / min), and the sum of the determined areas A (mm 2 ) and / or the sum of the areas B (mm 2 ) preferably also satisfies the following relational expression (b),

[0099] B / A≥3.2×10 -2 Q 2 +0.36Q-0.47 and

[0100] B / A≤-5.1×10 -2 Q 2 +1.1Q+0.62.

[0101] As also shown in the embodiment described later, this is because the flow of the cleaning liquid in the cleaning tank can be rectified more evenly. In addition, a modified example of determining the sum of the areas A and / or the sum of the areas B according to the supply flow rate will be described later.

[0102] In the workpiece cleaning method of the present invention, the distance between the two straightening plates is preferably at least 10 mm. This is because after the cleaning liquid passes through the lower straightening plate 5, a larger area is ensured to act as a buffer to reduce the flow rate, thereby ensuring a more uniform flow. Furthermore, the distance (the shortest distance) between the bottom of the cleaning tank 2 and the lower straightening plate 5 is also preferably at least 10 mm. This is because before the cleaning liquid is supplied from the cleaning liquid supply port 3 and reaches the lower straightening plate 5, a larger area is ensured to act as a buffer to reduce the flow rate, thereby ensuring a more uniform flow.

[0103] In the workpiece cleaning method of the present invention, the workpiece is preferably a wafer, and when the wafer is placed in the cleaning tank, the horizontal cross-sectional area of the cleaning tank at a height including the center of the wafer is 9000 mm. 2 Above and 60000mm 2 If the horizontal cross-sectional area is 9000mm 2 If the above-mentioned horizontal cross-sectional area is 60000mm, for example, a wafer with a diameter of 450mm can be accommodated. 2The amount of cleaning fluid used can be reduced. Furthermore, in a cleaning tank 2 of this size range, if the diameter of the holes 4a of the upper rectifying plate 4 is made smaller than the diameter of the holes 5a of the lower rectifying plate 5 and the above-mentioned relationship (a) (preferably the above-mentioned relationship (b)) is satisfied, a better rectifying effect can be obtained.

[0104] The embodiments of the present invention have been described above, but the present invention is not limited to the above-mentioned embodiments. For example, in the above-mentioned example, the supply flow rate Q is determined based on the relationship between the total area A and the total area B, but the total area A and / or the total area B can also be determined based on the supply flow rate Q. As an example, the value of B / A can be determined and A and / or B can be determined in a manner that satisfies the above-mentioned relationship (a) (preferably, the above-mentioned relationship (b) is also satisfied). In the invention of the method, it is sufficient to prepare a cleaning tank having a lower side rectifying plate and / or an upper side rectifying plate, and the lower side rectifying plate includes a plurality of holes having the total area A determined as above, and the upper side rectifying plate includes a total area B (mm) determined as above. 2 ) multiple holes, specifically, the rectifying plate can be replaced with a suitable hole diameter, for example, by sliding the rectifying plate to adjust the hole diameter. In the invention of the system, the system can also include a robot arm for performing the above replacement or a sliding adjustment mechanism for adjusting the hole diameter.

[0105] Furthermore, the implementation method of the above-mentioned workpiece cleaning processing method represents an example of using the above-mentioned workpiece cleaning processing system, but is not limited to this. For example, the determination of the supply flow Q performed in step S103 can also be performed on a computer different from the system, and the control of the determined supply flow performed in step S104 can also be performed by manual input.

[0106] In addition, regarding the sum of the areas A and B (mm 2 ) is used to determine the supply flow rate Q. In the above embodiment, the supply flow rate is determined based on B / A (specifically, based on the relational expression (a) (and the relational expression (b)), but the present invention is not limited thereto. That is, as will be shown in the embodiments described later, the relational expressions (a) and (b) represent the boundary lines where the effect can be obtained. The specific numerical expressions are merely for convenience and can be replaced in various ways. For example, instead of B / A, B / (A+1), B / A 2 And if the mathematical expression of Q is also divided into domains, it can be expressed by only a linear equation, for example. When using alternative mathematical expressions such as these, it is also desirable to pay attention to the sum of the areas A and B (mm 2) is used to determine the supply flow rate Q. The determined (resultant) A, B, and Q satisfy the aforementioned equation (a) (preferably, they also satisfy equation (b)). When determining the total area A and / or the total area B based on the supply flow rate Q, various mathematical equations can also be used.

[0107] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.

[0108] Example

[0109] (Example 1)

[0110] Set up two rectifier plates in the cleaning tank (such as Figure 1 The cleaning tank shown in the figure was used to measure the change in the amount of particles in the cleaning tank when pure water was continuously supplied. The time required for the amount of particles to reach 1 / 10 of the initial supply was measured. If it was less than 5 minutes, it was judged as "effective"; if it was more than 5 minutes and less than 20 minutes, it was judged as "slightly effective"; if it was more than 20 minutes, it was judged as "poorly effective" ( Figure 3 ).

[0111] The flow rate of the supplied pure water is within the range of 1 to 10 L / min and is graduated at 1 L / min. The diameter of the holes in the two rectifier plates is an integer value of φ1 to 5 mm, and the diameter of the holes in the upper rectifier plate is always smaller than the diameter of the holes in the lower rectifier plate. The total area A and B of the rectifier plates are changed by adjusting the diameter and number of holes. The holes are drilled in the rectifier plates to be evenly distributed. The openings of the liquid supply nozzles are drilled in the horizontal direction so that the cleaning liquid will not be sprayed directly toward the lower rectifier plate. The two rectifier plates are set to be 20 mm apart. The horizontal cross-sectional area of the cleaning tank is approximately 25,000 mm. 2 A rectangular cleaning tank.

[0112] exist Figure 3 , the dotted line represents the boundary line between the area that becomes "effective" or "slightly effective" and the area that becomes "poor effect", and these two boundary lines correspond to relational expression (a) (when the sign is equal in relational expression (a)). In addition, the boundary line is calculated based on the fitting method (fitting). And, the solid line represents the boundary line between the area that becomes "effective" and the area that becomes "slightly effective", and these two boundary lines correspond to relational expression (b) (when the sign is equal in relational expression (b)). According to this method, in the area that satisfies relational expression (a), it is "effective" or "slightly effective", and a rectification effect can be obtained, and in the area that satisfies relational expression (b), it is "effective", and a higher rectification effect can be obtained.

[0113] (Example 2)

[0114] Furthermore, using the same cleaning tank as in Example 1, the distance between the two rectifier plates was changed while the cleaning liquid was continuously supplied. The time required for the amount of particles per unit volume of the cleaning liquid to reach 1 / 10 of the amount at the start of the cleaning liquid supply was measured ( Figure 4 Here, the total liquid flow rate is set to 5 L / min and B / A=3.8.

[0115] like Figure 4 As shown, it is found that when the distance between the rectifying plates is less than 10 mm, it takes more than 5 minutes to reduce the amount of particles to 1 / 10, and this time increases rapidly as the distance between the rectifying plates becomes shorter.

[0116] Description of Reference Numerals

[0117] 1-Cleaning treatment system, 2-Cleaning tank, 3-Cleaning liquid supply port, 4-Upper side straightening plate, 5-Lower side straightening plate, 6-Calculation unit, 7-Control unit.

Claims

1. A method for cleaning a workpiece, comprising the following steps: Preparation of cleaning tank process; The step of placing a workpiece in the cleaning tank; and a step of supplying a cleaning liquid into the cleaning tank from a cleaning liquid supply port provided at the bottom of the cleaning tank to clean the workpiece; The cleaning method of the workpiece is characterized in that: Two rectifying plates are arranged between the position where the workpiece is set and the bottom, the two rectifying plates being composed of an upper rectifying plate and a lower rectifying plate, and the lower rectifying plate is located closer to the bottom side of the cleaning tank than the upper rectifying plate; The upper rectifying plate and the lower rectifying plate each have a plurality of holes; The diameter of the hole of the upper rectifying plate is smaller than the diameter of the hole of the lower rectifying plate; It also includes the sum of the areas A (mm) of the plurality of holes of the lower side rectifying plate. 2 ) and the sum of the areas of the plurality of holes of the upper rectifying plate B (mm 2 ) to determine the supply flow rate Q (L / min) of the cleaning liquid, in the process of supplying the cleaning liquid and cleaning the workpiece, the cleaning liquid is supplied at the determined supply flow rate Q (L / min), or the process further includes determining the total area A (mm2) according to the supply flow rate Q (L / min) 2 ) and / or the sum of the areas B (mm 2 ) process, in the process of preparing the cleaning tank, the cleaning tank is prepared with the lower side rectifying plate and / or the upper side rectifying plate, and the lower side rectifying plate includes the total area A (mm 2 ) of the plurality of holes, the upper side rectifying plate includes a total area B (mm 2 ) of the plurality of holes; The sum of the areas A (mm 2 ), the sum of the areas B (mm 2 ) and the determined supply flow rate Q (L / min), or the supply flow rate Q (L / min) and the sum A (mm2) of the determined areas 2 ) and / or the sum of the areas B (mm 2 ) satisfies the following relation (a), B / A≥5.6×10 -2 exp(0.46Q) and B / A≤-6.9×10 -2 Q 2 +1.2Q+3.4。 2. The workpiece cleaning method according to claim 1, wherein: The sum of the areas A (mm 2 ), the sum of the areas B (mm 2 ) and the determined supply flow rate Q (L / min), or the supply flow rate Q (L / min) and the sum A (mm2) of the determined areas 2 ) and / or the sum of the areas B (mm 2 ) also satisfies the following relation (b), B / A≥3.2×10 -2 Q 2 +0.36Q-0.47 and B / A≤-5.1×10 -2 Q 2 +1.1Q+0.62。 3. The workpiece cleaning method according to claim 1 or 2, wherein: The distance between the two rectifier plates is greater than 10 mm.

4. The workpiece cleaning method according to claim 1 or 2, wherein: The workpiece is a wafer, and when the wafer is placed in the cleaning tank, the horizontal cross-sectional area of the cleaning tank at a height including the center of the wafer is 9000 mm. 2 Above and 60000mm 2 the following.

5. A workpiece cleaning system comprising a cleaning tank, characterized in that: The cleaning tank is configured so that a workpiece can be placed in the cleaning tank; A cleaning liquid supply port is provided at the bottom of the cleaning tank for supplying cleaning liquid into the cleaning tank; Two rectifying plates are arranged between the position where the workpiece is placed and the bottom of the cleaning tank. The two rectifying plates are composed of an upper rectifying plate and a lower rectifying plate, and the lower rectifying plate is located closer to the bottom of the cleaning tank than the upper rectifying plate. The upper rectifying plate and the lower rectifying plate each have a plurality of holes; The diameter of the hole of the upper rectifying plate is smaller than the diameter of the hole of the lower rectifying plate; The system further includes a calculation unit that calculates the area of the plurality of holes of the lower straightening plate based on the total area A (mm 2 ) and the sum of the areas of the plurality of holes of the upper rectifying plate B (mm 2 ), determining a supply flow rate Q (L / min) of the cleaning liquid; and a control unit, controlling the supply of the cleaning liquid at the determined supply flow rate Q (L / min); The sum of the areas A (mm 2 ), the sum of the areas B (mm 2 ) and the supply flow rate Q (L / min) determined by the calculation unit satisfy the following relational expression (a), B / A≥5.6×10 -2 exp(0.46Q) and B / A≤-6.9×10 -2 Q 2 +1.2Q+3.4。 6. The workpiece cleaning system according to claim 5, wherein: The sum of the areas A (mm 2 ), the sum of the areas B (mm 2 ) and the determined supply flow rate Q (L / min) also satisfy the following relational expression (b), B / A≥3.2×10 -2 Q 2 +0.36Q-0.47 and B / A≤-5.1×10 -2 Q 2 +1.1Q+0.62。 7. The workpiece cleaning system according to claim 5 or 6, wherein: The distance between the two rectifier plates is greater than 10 mm.

8. The workpiece cleaning system according to claim 5 or 6, wherein: The workpiece is a wafer, and when the wafer is placed in the cleaning tank, the horizontal cross-sectional area of the cleaning tank at a height including the center of the wafer is 9000 mm. 2 Above and 60000mm 2 the following.

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