Manufacturing method of semiconductor device

Abstract

To ensure worker's safety, reduce environmental impact, and more reliably remove particles and metal contamination without increasing manufacturing costs.SOLUTION: When a semiconductor substrate constituting a semiconductor device is cleaned, a first step (step S1) of generating strong alkaline cleaning solution in a range of pH 11 to 14 in a cathode cell and generating strong acidic cleaning solution in a range of pH 1 to 3 in an anode cell by executing electrolytic treatment while supplying pure water to the cathode cell and the anode cell in a triple-chamber electrolytic apparatus in a state where a potassium chloride aqueous solution is stored in an intermediate cell in the triple-chamber electrolytic apparatus, a second step (step S2) of cleaning the semiconductor substrates by using the strong alkaline cleaning solution, a third step (step S3) of cleaning the semiconductor substrates by using the pure water, a fourth step (step S4) of cleaning the semiconductor substrates by using the strong acidic cleaning solution, and a fifth step (step S5) of cleaning the semiconductor substrates by using the pure water are executed in this order.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing semiconductor devices such as transistors, capacitors, memory cards, sensors, and image pickup devices. [Background technology]

[0002] As a method for manufacturing this type of semiconductor device, the applicant has disclosed in the following patent document a method for manufacturing a semiconductor device characterized by cleaning a semiconductor substrate using a strong alkaline cleaning solution.

[0003] Specifically, the manufacturing method disclosed by the applicant first includes an electrolytic treatment tank having an anode electrode disposed therein and filled with an electrolyte solution, a cathode electrode disposed therein and connected to a first pipe for introducing ultrapure water and a second pipe for discharging electrolytically reduced water, and a cation exchange membrane disposed between the first and second tanks. A voltage is applied between the anode electrode and the cathode electrode by a DC power supply to generate electrolytically reduced water from the ultrapure water introduced into the second tank. The generated electrolytically reduced water is then used as a cleaning solution to clean semiconductor substrates using a single-wafer cleaning machine or an immersion cleaning machine. This removes particles and metal contamination from the surfaces of the semiconductor substrates. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6317580 (pages 3-5, figures 1-3) Summary of the Invention [Problem to be solved by the invention]

[0005] However, the semiconductor device manufacturing method disclosed by the applicant has the following problems that need to be improved.

[0006] Specifically, the manufacturing method disclosed by the applicant is characterized in that strongly alkaline electrolytically reduced water produced by electrolysis using a two-tank electrolytic processing device is used as a cleaning solution, and semiconductor substrates are cleaned using a single-wafer cleaning machine or an immersion cleaning machine to remove particles and metal contamination from the surface of the semiconductor substrate. As a result, unlike manufacturing methods that clean semiconductor substrates using, for example, an RCA cleaning solution, the manufacturing method disclosed by the applicant does not generate large amounts of toxic gas during cleaning, making it unnecessary to remove (treat) this toxic gas, and also making it possible to significantly reduce the processing costs required for treating the waste liquid (cleaning liquid) after cleaning.

[0007] However, depending on the content and processing environment of the processing steps performed before the cleaning step, the degree of metal contamination occurring on the semiconductor substrate to be cleaned may be high, making it difficult to adequately remove this contamination using the above-mentioned manufacturing method. In this case, it is possible to prepare a cleaning solution suitable for removing metal contamination in addition to the strongly alkaline cleaning solution used in the above-mentioned manufacturing method, but in that case, the manufacturing cost of the semiconductor device (the cost required to clean the semiconductor substrate) will rise due to the need to prepare two separate cleaning solutions. Furthermore, depending on the type of cleaning solution used, the processing costs required to treat the waste liquid so as not to cause environmental damage and the processing costs for removing toxic gases so as not to compromise the safety of workers will rise, which may make it difficult to reduce the manufacturing cost of the semiconductor device.

[0008] The present invention has been made in consideration of these problems, and its main object is to provide a method for manufacturing a semiconductor device that can more reliably remove particles and metal contamination from the surface of a semiconductor substrate without increasing manufacturing costs, while ensuring the safety of workers and reducing the environmental load. [Means for solving the problem]

[0009] To achieve the above object, a method for manufacturing a semiconductor device according to claim 1 includes, when cleaning a semiconductor substrate that constitutes a semiconductor device during the manufacture of the semiconductor device, performing an electrolysis process while storing a potassium chloride aqueous solution in an intermediate tank of a three-compartment electrolytic device and supplying pure water to each of a cathode tank and an anode tank of the three-compartment electrolytic device, thereby producing strong alkaline cleaning water having a pH of 11 to 14 in the cathode tank and strong acidic cleaning water having a pH of 1 to 3 in the anode tank; cleaning the semiconductor substrate with the strong alkaline cleaning solution; cleaning the semiconductor substrate with pure water; cleaning the semiconductor substrate with pure water; and cleaning the semiconductor substrate with pure water, in this order.

[0010] A semiconductor device manufacturing method according to claim 2 is the method according to claim 1, wherein the semiconductor substrate is cleaned using a single-wafer cleaning machine in the second, third, fourth and fifth steps.

[0011] A semiconductor device manufacturing method according to a third aspect of the present invention is the method of manufacturing a semiconductor device according to the first aspect of the present invention, wherein the semiconductor substrate is cleaned using an immersion cleaner in the second, third, fourth and fifth steps. [Effects of the Invention]

[0012] In a method for manufacturing a semiconductor device according to the present invention, a potassium chloride aqueous solution is stored in an intermediate tank of a three-compartment electrolysis system, and pure water is supplied to the cathode and anode tanks of the three-compartment electrolysis system while electrolysis is performed. This produces a strongly alkaline cleaning solution having a pH of 11 to 14 in the cathode tank and a strongly acidic cleaning solution having a pH of 1 to 3 in the anode tank. The following steps are performed in this order: a first step, in which a semiconductor substrate is cleaned using the strongly alkaline cleaning solution; a third step, in which the semiconductor substrate is cleaned using pure water; a fourth step, in which the semiconductor substrate is cleaned using the strongly acidic cleaning solution; and a fifth step, in which the semiconductor substrate is cleaned using pure water. Specifically, in the method for manufacturing a semiconductor device according to the present invention, the semiconductor substrate is cleaned using a single-wafer cleaning machine in the second, third, fourth, and fifth steps. Furthermore, in the method for manufacturing a semiconductor device according to the present invention, the semiconductor substrate is cleaned using an immersion cleaning machine in the second, third, fourth, and fifth steps.

[0013] Therefore, according to the semiconductor device manufacturing method of the present invention, metal contamination that is difficult to remove by cleaning with a strong alkaline cleaning solution alone can be effectively removed by cleaning with a strong acidic cleaning solution. Furthermore, as with the semiconductor device manufacturing method disclosed by the applicant, no toxic gases are generated during the generation of the strong alkaline cleaning solution or the cleaning using the generated cleaning solution, ensuring sufficient safety. Furthermore, waste liquid after cleaning can be easily disposed of, resulting in low-cost and reduced environmental impact. Furthermore, since the strong alkaline cleaning solution and the strong acidic cleaning solution can be simultaneously generated by a single electrolytic treatment, the cost of generating the cleaning solution can be significantly reduced. Therefore, the cost required for cleaning the substrate to be cleaned, and ultimately the cost of manufacturing various semiconductor devices manufactured using the substrate to be cleaned, can be significantly reduced. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing the configuration of a cleaning liquid generating device 1. FIG. [Figure 2]FIG. 2 is a diagram showing the configuration of a substrate cleaning apparatus 2. [Figure 3] 1 is a flowchart of a substrate cleaning process 30. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the "semiconductor device manufacturing method" will be described with reference to the accompanying drawings.

[0016] For example, when manufacturing semiconductor devices such as transistors, capacitors, memory cards, sensors, and image sensors, a cleaning process is performed to clean the processed semiconductor substrate after performing various processes such as film formation and polishing processes on the semiconductor substrate. Here, in the cleaning process in the semiconductor device manufacturing method according to the present invention, a cleaning liquid generating apparatus 1 shown in Fig. 1 and a substrate cleaning apparatus 2 shown in Fig. 2 are used to perform a substrate cleaning process 30 shown in Fig. 3, thereby cleaning a substrate X to be cleaned (see Fig. 2), which is an example of a semiconductor substrate.

[0017] 1, the cleaning solution generation apparatus 1 is an example of a "three-chamber electrolysis apparatus" and is equipped with an electrolytic cell 10 having a cathode cell 11 (cathode chamber) which is an example of a "cathode cell," an anode cell 12 (anode chamber) which is an example of an "anode cell," and an intermediate cell 13 (electrolyte storage chamber) which is an example of an "intermediate cell," and a DC power supply 15. In this cleaning solution generation apparatus 1, the cathode cell 11 and the intermediate cell 13 are separated by a cation exchange membrane 14a, and the anode cell 12 and the intermediate cell 13 are separated by an anion exchange membrane 14b, and the DC power supply 15 is connected to the cathode 11a (cathode electrode) disposed in the cathode cell 11 and the anode 12a (anode electrode) disposed in the anode cell 12.

[0018] 2, the substrate cleaning apparatus 2 is an example of a "single wafer cleaning machine" and is equipped with a turntable 21 configured to be able to place a substrate X to be cleaned, and a nozzle 22 that supplies various processing liquids to the substrate X to be cleaned on the turntable 21. Note that the configuration of the substrate cleaning apparatus 2 (single wafer cleaning machine) is well known, and therefore detailed illustrations and explanations will be omitted.

[0019] When cleaning a substrate X to be cleaned by this substrate cleaning process 30, first, a strong alkaline cleaning solution W1 and a strong acid cleaning solution W2 are generated using the cleaning solution generating apparatus 1 (step S1, an example of a "first step"). Specifically, as shown in FIG. 1, an aqueous potassium chloride solution Wa is stored in an intermediate tank 13 in the cleaning solution generating apparatus 1. In this case, the aqueous potassium chloride solution Wa is an aqueous solution whose potassium chloride concentration has been adjusted according to the conditions for generating the strong alkaline cleaning solution W1 and the strong acid cleaning solution W2 by the cleaning solution generating apparatus 1 (such as the amount generated per unit time and the electrolysis processing capacity of the cleaning solution generating apparatus 1). As described below, the aqueous potassium chloride solution Wb, whose potassium chloride concentration has been reduced by generating the strong alkaline cleaning solution W1 and the strong acid cleaning solution W2, is transferred from the intermediate tank 13 to a concentration adjustment processing tank (not shown), where the potassium chloride concentration is adjusted, and the aqueous potassium chloride solution Wa is stored again in the intermediate tank 13.

[0020] Next, ultrapure water W0, which is an example of "pure water," is flowed into the cathode chamber 11 and the anode chamber 12, respectively, and a DC voltage is applied between the cathode 11a and the anode 12a from the DC power supply 15. At this time, potassium ions (K+) move from the intermediate chamber 13 through the cation exchange membrane 14a into the cathode chamber 11, producing a strongly alkaline cleaning solution W1 with a pH in the range of about 11 to 14 (for example, about pH 13), and chloride ions (Cl-) move from the intermediate chamber 13 through the anion exchange membrane 14b into the anode chamber 12, producing a strongly acidic cleaning solution W2 with a pH in the range of 1 to 3 (for example, about pH 2). This completes the production of the "cleaning solution" for cleaning the substrate X to be cleaned.

[0021] Next, the substrate X to be cleaned is set on the turntable 21 of the substrate cleaning apparatus 2, and then cleaning of the substrate X to be cleaned is performed using the strong alkaline cleaning liquid W1 (step S2: an example of the "second process"). At this time, for example, the turntable 21 is rotated at 50 to 1000 rpm (for example, 100 rpm), and the strong alkaline cleaning liquid W1 is supplied from the nozzle 22 to the substrate X to be cleaned on the turntable 21, and this state is maintained for 30 to 90 seconds (for example, 60 seconds). As a result, foreign matter such as particles adhering to the surface of the substrate X to be cleaned is removed, as will be described later.

[0022] Next, the substrate X to be cleaned is cleaned using ultrapure water W0 (step S3, an example of a "third step"). At this time, for example, while the turntable 21 is rotated at 50 to 1000 rpm (for example, while maintaining 100 rpm), the ultrapure water W0 is supplied from the nozzle 22 to the substrate X to be cleaned on the turntable 21, and this state is maintained for 90 to 150 seconds (for example, 120 seconds). As a result, the strong alkaline cleaning solution W1 used in the cleaning in step S2 is removed from the substrate X to be cleaned.

[0023] Next, cleaning of the substrate X to be cleaned using the strong acid cleaning liquid W2 is performed (step S4, an example of the "fourth step"). At this time, for example, while the turntable 21 is rotated at 50 to 1000 rpm (for example, while maintaining 100 rpm), the strong acid cleaning liquid W2 is supplied from the nozzle 22 to the substrate X to be cleaned on the turntable 21, and this state is maintained for 30 to 90 seconds (for example, 60 seconds). As a result, as will be described later, metal contamination present on the surface of the substrate X to be cleaned is removed.

[0024] Next, the substrate X to be cleaned is cleaned using ultrapure water W0 (step S5, an example of the "fifth step"). At this time, for example, while the turntable 21 is rotated at 50 to 1000 rpm (for example, while maintaining 100 rpm), the ultrapure water W0 is supplied from the nozzle 22 to the substrate X to be cleaned on the turntable 21, and this state is maintained for 90 to 150 seconds (for example, 120 seconds). As a result, the strong acid cleaning solution W2 used in the cleaning in step S4 is removed from the substrate X to be cleaned.

[0025] Although an example has been described in which the rotation speed of the turntable 21 is maintained at 100 rpm in the four processes of steps S2 to S5, the rotation speed of the turntable 21 in each process can be appropriately changed, along with the supply amounts per unit time of both cleaning liquids W1, W2 and ultrapure water W0, and the time for which these are maintained in supply state, so as to perform suitable cleaning.

[0026] Thereafter, for example, the turntable 21 is rotated at 500 to 2000 rpm (for example, 1000 rpm) and this state is maintained for 30 to 90 seconds (for example, 60 seconds), thereby removing the ultrapure water W0 used for cleaning in step S5 and drying the cleaning target substrate X (step S6). Note that, regarding the drying process of the cleaning target substrate X, the time required for drying can also be shortened by blowing nitrogen or dry air onto the cleaning target substrate X while rotating the turntable 21 (cleaning target substrate X) as described above. With the above, cleaning of the cleaning target substrate X is completed.

[0027] In the cleaning target substrate X cleaned by the substrate cleaning process 30, foreign matter such as particles adhering to the surface of the cleaning target substrate X is preferably removed by the cleaning process in step S2 using the strong alkaline cleaning solution W1, just like in the semiconductor substrate cleaned by the cleaning step in the semiconductor device manufacturing method disclosed by the applicant in the aforementioned patent document. Furthermore, in the cleaning target substrate X cleaned by the substrate cleaning process 30, metal contamination on the surface of the cleaning target substrate X is also preferably removed by cleaning with the strong acid cleaning solution W2 performed after the cleaning process in step S2 (specifically, after step S3 in which the strong alkaline cleaning solution W1 is removed).

[0028] In this case, metal contamination on the surface of the substrate X to be cleaned often occurs at locations where foreign matter such as particles is attached, and when foreign matter is attached to the surface of the substrate X to be cleaned, it can be difficult to remove the metal contamination underneath. However, in the cleaning process (substrate cleaning process 30) in the semiconductor device manufacturing method of this example, the foreign matter on the surface of the substrate X to be cleaned is suitably removed by the cleaning process of step S2, as described above. As a result, the metal contamination is also sufficiently removed by the strong alkaline cleaning solution W1 during the cleaning process of step S2, and further, the metal contamination is even more suitably removed by the cleaning process of step S4 with the strong acidic cleaning solution W2. Therefore, even if the level of metal contamination on the surface of the substrate X to be cleaned is relatively high, it is possible to reliably remove it.

[0029] Furthermore, in the substrate cleaning process 30, similar to the semiconductor device manufacturing method disclosed by the applicant in the aforementioned patent document, no toxic gases harmful to humans are generated during the generation of the strong alkaline cleaning solution W1 or the strong acid cleaning solution W2 in step S1 or during the subsequent cleaning process, ensuring the safety of workers. Furthermore, in the substrate cleaning process 30, the used strong alkaline cleaning solution W1 or the strong acid cleaning solution W2, as well as the ultrapure water W0 used to remove them, can be easily disposed of without causing environmental damage, thereby making it possible to sufficiently reduce waste liquid disposal costs and sufficiently reduce the environmental load.

[0030] Although the above description concerns an example in which cleaning with the strong alkaline cleaning solution W1 or the strong acid cleaning solution W2 is performed using the substrate cleaning apparatus 2, which is a "single-wafer cleaning machine," it has been confirmed that similar effects to those achieved by the above-described substrate cleaning process 30 can also be achieved when cleaning with the strong alkaline cleaning solution W1 or the strong acid cleaning solution W2 is performed using an "immersion cleaning machine" (not shown) instead of the substrate cleaning apparatus 2. In this case, the drying process for the substrate X to be cleaned after cleaning with the "immersion cleaning machine" (the process corresponding to step S6 in the substrate cleaning process 30) can be performed by blowing dry air or nitrogen onto the substrate X to dry it, or by drying it by a hot pure water lift-up and alcohol substitution method.

[0031] Next, a specific description will be given of the change in metal contamination depending on whether or not steps S4 and S5 in the substrate cleaning process 30 are performed.

[0032] Two substrates X to be cleaned (e.g., 8-inch diameter silicon substrates) were produced under the same production environment. One of the substrates was subjected to Si polishing on its surface, and the other was subjected to finish polishing on its surface, and the levels of metal contamination were measured for sample A when only cleaning with the strong alkaline cleaning solution W1 and ultrapure water W0 in steps S2 and S3 of the substrate cleaning process 30 was performed (when cleaning with the strong acid cleaning solution W2 in step S4 was not performed), and when cleaning with the strong acid cleaning solution W2 and ultrapure water W0 in steps S4 and S5 was performed following cleaning in steps S2 and S3.

[0033] For Si polishing, a stock solution of 30 nm particle size silica slurry (Fujimi Incorporated's "GRANZOX-1302") dispersed in an alkaline solution of pH 11.6 was diluted 10 times with pure water. The polishing agent was used to polish the surface of the substrate X to a depth of 2 μm using a polishing machine (Okamoto Machine Tools Works: SPP800S) and a nonwoven fabric pad (Nitta Haas: SUBA#400). For finish polishing, a stock solution of 12 nm particle size silica slurry (Fujimi Incorporated's "GLANZOX3105") dispersed in an alkaline solution of pH 10.6 was diluted 30 times with pure water. The polishing agent was used to polish the surface to a surface roughness Ra ≦ 0.2 nm using a polishing machine (Okamoto Machine Tools Works: SPP800S) and a suede pad (Nitta Haas: RN-H).

[0034] Furthermore, the degree of metal contamination was measured by total reflection X-ray fluorescence analysis using, as an example, a total reflection X-ray fluorescence analyzer "TXRF" manufactured by Rigaku Electric Co., Ltd. (currently Rigaku Corporation). Regarding the measurement results, the level of metal contamination when only steps S2 and S3 were performed is shown in [Table 1], and the level of metal contamination when steps S2 to S5 were performed is shown in [Table 2].

[0035] [Table 1]

[0036] [Table 2]

[0037] As shown in "Table 1," sample A, which was subjected to only Si polishing, showed partial metal contamination with iron (Fe) and zinc (Zn) after cleaning with the strong alkaline cleaning solution W1. Similarly, sample B, which was subjected to Si polishing and finish polishing, also showed partial metal contamination with iron (Fe) after cleaning with the strong alkaline cleaning solution W1. On the other hand, as shown in "Table 2," samples A and B, which showed partial metal contamination after cleaning with the strong alkaline cleaning solution W1, showed a sufficiently low level of partial metal contamination with iron (Fe) and zinc (Zn) after cleaning with the strong acidic cleaning solution W2. These results demonstrate that cleaning with the strong alkaline cleaning solution W1 followed by cleaning with the strong acidic cleaning solution W2 effectively removes metal contamination from the surface of the substrate X to be cleaned.

[0038] Although the measurement results for one sample A and one sample B have been shown and explained, when the degree of metal contamination was measured for multiple samples A and multiple samples B using the same procedure as in the above example, it was confirmed that the degree of metal contamination was lower for each sample B that had been cleaned with the strong acid cleaning solution W2 than for each sample A that had not been cleaned with the strong acid cleaning solution W2. Furthermore, although the removal of metal contamination has been explained, it has been confirmed that foreign matter such as particles adhering to the surface of the substrate X to be cleaned can be suitably removed by cleaning in step S2 using the strong alkaline cleaning solution W1, in the same way as when cleaning is performed using the semiconductor device manufacturing method disclosed by the applicant in the aforementioned patent document.

[0039] Thus, in this semiconductor device manufacturing method (substrate cleaning process 30), an electrolysis process is performed while storing a potassium chloride aqueous solution (potassium chloride aqueous solution Wa) in the intermediate tank (intermediate tank 13) of a three-chamber electrolytic apparatus (cleaning solution generating apparatus 1) and supplying pure water (ultrapure water W0) to the cathode tank (cathode tank 11) and the anode tank (anode tank 12) of the three-chamber electrolytic apparatus, thereby producing a first step (step S0) of producing a strongly alkaline cleaning water (strongly alkaline cleaning solution W1) with a pH range of 11 to 14 in the cathode tank and a strongly acidic cleaning water (strongly acidic cleaning solution W2) with a pH range of 1 to 3 in the anode tank, a second step (step S2) of cleaning a semiconductor substrate with the strongly alkaline cleaning solution, a third step (step S3) of cleaning a semiconductor substrate with pure water, a fourth step (step S4) of cleaning a semiconductor substrate with the strongly acidic cleaning solution, and a fifth step (step S5) of cleaning a semiconductor substrate with pure water, in this order. Specifically, in this semiconductor device manufacturing method, the semiconductor substrate is cleaned using a single-wafer cleaning machine in the second, third, fourth, and fifth steps (steps S2 to S5). Also, in this semiconductor device manufacturing method, the semiconductor substrate is cleaned using an immersion cleaning machine in the second, third, fourth, and fifth steps (steps S2 to S5).

[0040] Therefore, according to this semiconductor device manufacturing method, metal contamination that is difficult to remove by cleaning with the strong alkaline cleaning solution W1 alone can be effectively removed by cleaning with the strong acid cleaning solution W2. Furthermore, as with the semiconductor device manufacturing method disclosed by the applicant, no toxic gases are generated during the generation of the strong alkaline cleaning solution W1 and the strong acid cleaning solution W2 or during cleaning using the generated cleaning solutions W1 and W2, ensuring sufficient safety. Furthermore, waste liquid after cleaning can be easily disposed of, resulting in low-cost and reduced environmental impact. Furthermore, since the strong alkaline cleaning solution W1 and the strong acid cleaning solution W2 can be simultaneously generated by a single electrolytic treatment, the cost of generating the cleaning solutions can be significantly reduced. Therefore, the cost required for cleaning the substrate X to be cleaned, and ultimately the cost of manufacturing various semiconductor devices manufactured using the substrate X to be cleaned, can be significantly reduced. [Industrial Applicability]

[0041] According to the present invention, cleaning is performed using a three-chamber electrolysis device and a strongly alkaline cleaning solution and a strongly acidic cleaning solution produced by electrolysis using an aqueous potassium chloride solution as the electrolyte. This makes it possible to effectively remove foreign matter such as particles and metal contamination from the surface of a semiconductor substrate without compromising the safety of workers or causing environmental damage, and therefore the present invention can be widely applied when manufacturing semiconductor devices using semiconductor substrates. [Explanation of symbols]

[0042] 1. Cleaning liquid generator 2. Substrate cleaning equipment 10 Electrolytic cell 11 Cathode bath 11a Cathode 12 Anode tank 12a anode 13 Intermediate tank 14a Cation exchange membrane 14b Anion exchange membrane 15 DC power supply 21 Turntable 22 nozzles 30 Substrate cleaning process W0 Ultrapure water Wa,Wb Potassium chloride aqueous solution W1 Strong alkaline cleaning solution W2 Strong Acid Cleaning Solution X Cleaning target substrate

Claims

1. When cleaning a semiconductor substrate that constitutes a semiconductor device during manufacturing of the semiconductor device, a first step of storing an aqueous potassium chloride solution in an intermediate tank of a three-compartment electrolysis device and supplying pure water to a cathode tank and an anode tank of the three-compartment electrolysis device, and performing electrolysis treatment to produce strong alkaline cleaning water having a pH in the range of 11 to 14 in the cathode tank and strong acidic cleaning water having a pH in the range of 1 to 3 in the anode tank; a second step of cleaning the semiconductor substrate using the strong alkaline cleaning solution; a third step of cleaning the semiconductor substrate with pure water; a fourth step of cleaning the semiconductor substrate using the strong acid cleaning solution; and a fifth step of cleaning the semiconductor substrate with pure water.

2. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate is cleaned using a single-wafer cleaning machine in the second, third, fourth and fifth steps.

3. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate is cleaned using an immersion cleaner in the second, third, fourth and fifth steps.

Images