JP2005285989A - Method for cleaning semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove the contamination of a wafer back face without deteriorating the components of a cleaning device such as a nozzle to be used for cleaning the wafer back face, by cleaning the wafer back face by using chemical which does not generate heat even when it is mixed with water at the time of carrying out resist peeling and cleaning in a sheet type cleaning device. <P>SOLUTION: At the time of carrying out the resist peeling and cleaning of a semiconductor wafer by a sheet type cleaning device, the back face of the wafer is cleaned by using chemical which does not generate heat even when it is mixed with water. In this case, solution obtained by mixing aqueous ammonia and oxygenated water which is alkali system chemical and water, or solution constituted of dilution aqueous ammonia or potassium hydroxide solution may be used as chemical. Also, solution obtained by mixing chlorine and oxygenated water which is acid system chemical and water, or solution obtained by mixing hydrogen fluoride, hydrogen chloride, oxygenated water and water or solution obtained by mixing hydrogen fluoride, oxygenated water and water may be used as chemical. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for cleaning a semiconductor wafer. More specifically, the present invention relates to wafer back surface cleaning in resist strip cleaning.

For example, in a process of removing a photoresist film in a cleaning process of a semiconductor wafer such as silicon, a so-called resist peeling process, a chemical solution (hereinafter referred to as an SPM solution) in which sulfuric acid and hydrogen peroxide water are mixed (H ₂ SO ₄ / H ₂ O ₂ ). (Abbreviated) is generally used. Also, in recent years, the trend of large-diameter semiconductor wafers and small-lot, multi-product production has progressed, and the transition from the conventional dip-type batch cleaning system to the spray-type single wafer cleaning system has been studied. Yes.

As a resist stripping apparatus and resist stripping method required when manufacturing a semiconductor device, a semiconductor wafer is supported on a rotary table, and while rotating the semiconductor wafer, from the nozzle toward the center of the resist coating surface of the semiconductor wafer Patent Document 1 describes a technique in which a resist stripping solution is dropped, and the resist stripping solution is spread over the entire surface by centrifugal force to react with the resist and strip.
Japanese Patent Laid-Open No. 11-288871

  By the way, when performing SPM solution cleaning by the single wafer cleaning method, it is conceivable to perform resist removal of the semiconductor wafer surface by SPM solution cleaning and also to perform SPM solution cleaning on the back surface of the semiconductor wafer. On the other hand, as a single wafer cleaning apparatus, a single wafer cleaning apparatus having a wafer rotating mechanism is conceivable. In the case of a single wafer cleaning device having this wafer rotation mechanism, a plurality of nozzles such as a nozzle for discharging a chemical solution and a nozzle for rinsing (washing with water, etc.) after cleaning the wafer surface are disposed on the wafer surface side. The nozzle for discharging chemicals on the back side of the wafer can be installed only at the rotating shaft. For this reason, it is common to have only one nozzle on the back side of the wafer.

  Also, since rinsing (washing, etc.) after wafer backside cleaning is indispensable, if both water washing and SPM solution washing are performed with a single nozzle, each reacts and generates heat, including a chemical solution discharge nozzle. Equipment parts will deteriorate. For this reason, it is necessary to use a chemical solution that does not deteriorate the device parts by reacting with water for the wafer back surface cleaning.

  In addition, since contaminants such as organic substances such as resist adhere to the back surface of the wafer before the resist stripping process, the contamination of the chamber introduced after the resist stripping process and further transfer from the chamber. Problems such as a reduction in the yield rate due to wafer contamination occur.

  In view of the above, the present invention provides a method for cleaning a semiconductor wafer in which organic contamination such as resist on the back surface of the wafer can be removed during resist peeling cleaning of the semiconductor wafer without deteriorating the components of the cleaning apparatus. Is.

  The semiconductor wafer cleaning method according to the present invention is characterized in that, when performing resist peeling cleaning of a semiconductor wafer by a single wafer cleaning apparatus, cleaning of the back surface of the wafer is performed using a chemical solution that does not generate heat even when mixed with water. .

As the chemical used for cleaning the back surface of the wafer, it is preferable to use a chemical that can remove organic contamination. As the chemical solution, an alkaline chemical solution or an acid chemical solution can be used.
Examples of the alkaline chemical solution include a mixed solution of ammonia water (NH ₄ OH), hydrogen peroxide solution (H ₂ O ₂ ), and water (H ₂ O) (abbreviated as SC1 solution), or diluted ammonia water (dNH ₄ OH) or potassium hydroxide (KOH) solution can be used.
As an acid chemical solution, a solution (abbreviated as SC2 solution) in which hydrogen chloride (HCl), hydrogen peroxide solution (H ₂ O ₂ ), and water (H ₂ O) are mixed, or hydrogen fluoride (HF) and chloride. A mixed solution of hydrogen (HCl), hydrogen peroxide solution (H ₂ O ₂ ), and water (H ₂ O) (abbreviated as FHPM solution), or hydrogen fluoride (HF) and hydrogen peroxide solution (H ₂ O) ₂ ) and water (H ₂ O) mixed solution (abbreviated as FPM solution) can be used.

  In the wafer backside cleaning, when the chemical treatment is performed, it is preferable to cover the wafer surface with an inert liquid or gas.

  According to the method for cleaning a semiconductor wafer according to the present invention, at the time of resist stripping cleaning in a single wafer cleaning apparatus, the wafer backside cleaning is performed by using a chemical solution that does not generate heat even when mixed with water. Contamination on the back surface of the wafer can be removed without deteriorating the parts of the cleaning device such as the nozzle.

As a chemical solution for wafer back surface cleaning, a solution (NH ₄ OH / H ₂ O ₂ / H ₂ O) obtained by mixing ammonia water, hydrogen peroxide water and water, which is an alkaline chemical solution, or diluted ammonia water (dNH ₄ OH). By using a chemical solution such as a solution or a potassium hydroxide (KOH) solution, the contamination level on the wafer back surface can be further reduced.
Alternatively, as a chemical solution for cleaning the wafer back surface, a solution (HCl / H ₂ O ₂ / H ₂ O) in which hydrogen chloride, which is an acid chemical solution, hydrogen peroxide water, and water is mixed, or hydrogen fluoride, hydrogen chloride, and hydrogen peroxide. A solution in which water and water are mixed (HF / HCl / H ₂ O ₂ / H ₂ O), or a solution in which hydrogen fluoride, hydrogen peroxide water and water are mixed (HF / H ₂ O ₂ / H ₂ O), etc. By using this chemical solution, the contamination level on the back surface of the wafer can be further reduced.

Further, by covering the wafer surface with an inert liquid or gas during the wafer back surface cleaning, even if a chemical solution used for wafer back surface processing wraps around the wafer surface, the wafer surface is not altered.
Therefore, by using the semiconductor wafer cleaning method according to the present invention described above, it is possible to increase the non-defective product rate in the state of the semiconductor wafer, and further the non-defective product rate of semiconductor devices manufactured from the semiconductor wafer. In addition, the maintenance frequency of the processing chamber itself of the single wafer cleaning apparatus can be reduced. That is, since the wafer back surface cleaning is performed using a chemical solution that does not generate heat even when mixed with water, for example, the frequency of replacement of components such as nozzles can be reduced.

  Embodiments of the present invention will be described below.

  FIG. 1 shows an outline of a single wafer rotary cleaning apparatus having a wafer rotating mechanism, particularly an apparatus main body, which is applied to the semiconductor wafer cleaning method of the present invention. This single wafer rotary cleaning apparatus 1 has a rotating substrate 3 that is rotatably arranged by a rotating shaft 2, and a wafer support member 4 that supports a plurality of, for example, four semiconductor wafers 6 is implanted on the rotating substrate 3. Is standing. Above the rotating substrate 3, there are a plurality of nozzles 5 [5A, 5A, 5A, 5A, 5A, etc. 5B] is disposed. For example, the nozzle 5A can be used for an SPM solution, and the nozzle 5B can be used for an SC1 / rinse solution, for example. In addition, since it is easy to arrange a plurality of nozzles on the wafer surface side, it is preferable to use one nozzle for one chemical solution. On the other hand, at the portion of the rotating shaft 2 corresponding to the wafer back surface 6b, a single nozzle 7 serving both as a chemical solution discharge and a rinse solution (for example, water) discharge for cleaning contamination of the wafer back surface 6b is disposed. The nozzle 7 is integrally formed so as to penetrate the shaft core portion of the rotating shaft 2. In this single wafer cleaning apparatus 1, a semiconductor wafer 6 to be cleaned is disposed on the wafer support member 4 so as to support the periphery of the semiconductor wafer 6, and in this state, the rotating shaft 2 is rotated to rotate the rotating substrate 3 together with the semiconductor. The wafer 6 is rotated. On the other hand, a chemical solution 8 for removing the resist is discharged from above through the nozzle 5A, and the resist film on the semiconductor wafer surface 6a is peeled and removed, and then, for example, water is discharged from the nozzle 5B for cleaning (rinsing treatment). Is done. For the wafer back surface 6b, a required chemical solution is discharged through a nozzle 7 provided integrally with the rotary shaft 2 to decontaminate the wafer, and then, for example, water or the like of the rinse liquid is discharged to clean the wafer back surface 6b (rinse treatment). Do.

  In the present embodiment, when the resist film on the semiconductor wafer surface 6a is peeled and removed by using the single wafer rotary cleaning apparatus 1 described above, as a chemical liquid for resist peeling, a commonly used chemical liquid, for example, SPM is used. Use solution. On the other hand, as the chemical solution for removing the contamination on the wafer back surface 6b, an alkaline chemical solution or an acid chemical solution can be used. The alkaline chemical solution and the acid chemical solution require a chemical solution that does not generate heat even when mixed with water. Further, the alkaline chemical solution and the acid chemical solution require a chemical solution that can remove organic contamination such as a resist.

For this reason, as the alkaline chemical, a solution (SC1 solution) obtained by mixing ammonia water (NH ₄ OH), hydrogen peroxide water (H ₂ O ₂ ), and water (H ₂ O), or diluted aqueous ammonia (dNH ₄ Suitably a solution consisting of OH) or a potassium hydroxide (KOH) solution is used. In addition, as an acid chemical solution, a solution (SC2 solution) obtained by mixing hydrogen chloride (HCl), hydrogen peroxide solution (H ₂ O ₂ ), and water (H ₂ O), or hydrogen fluoride (HF) and hydrogen chloride. (HCl), hydrogen peroxide solution (H ₂ O ₂ ) and water (H ₂ O) mixed solution (FHPM solution), or hydrogen fluoride (HF), hydrogen peroxide solution (H ₂ O ₂ ) and water It is appropriate to use a solution (FPM solution) mixed with (H ₂ O).

In addition, when cleaning the wafer backside with the above chemical solution, in order to prevent chemicals from flowing into the wafer surface side and oxidizing the elements on the wafer surface, the wafer surface is inactive such as with water during chemical cleaning on the wafer backside. Or an inert gas such as N ₂ gas, Ar gas, H ₂ gas, or forming gas.

As the cleaning process for cleaning the resist on the wafer back surface along with the resist peeling cleaning of the wafer surface 6a using the above-described chemical solution, the following processes can be employed. For example, contamination removal can be performed on the wafer back surface 6b using the above chemical solution in a pre-process and / or a post-process of a resist stripping process using an SPM solution for the wafer front surface 6a. When the contamination removal of the wafer back surface 6b is performed with the chemical solution in the previous step, the chemical solution treatment may be performed only on the wafer surface 6a in the subsequent step. When the wafer back surface 6b is decontaminated with the chemical solution, it is preferable to cover the wafer surface 6a with an inert liquid or gas. In any case, the front and back surfaces 6a and 6b of the wafer are rinsed with a liquid such as pure water, warm pure water or diluted hydrogen chloride water in the final step.
Further, the chemical treatment for the wafer surface 6a and / or the wafer back surface 6b in the post-process is omitted, and the wafer front and back surfaces 6a and 6b are immediately rinsed after the resist stripping process with the SPM solution for the wafer surface 6a. You can also.

It is also possible to first perform the resist stripping process on the wafer front surface 6a with the SPM solution, then perform the above chemical treatment on the wafer back surface 6b, and finally perform the rinse processing on the wafer front and back surfaces 6a and 6b. At the time of the chemical treatment for the wafer back surface 6b, the wafer surface 6a may be simultaneously covered with the chemical treatment or an inert liquid or gas.
Furthermore, the wafer surface 6a can be first subjected to resist stripping with the SPM solution, and at the same time, the wafer back surface 6b can be subjected to the above chemical treatment, and then the wafer front and back surfaces 6a and 6b can be rinsed.

  According to the present embodiment, in the photoresist peeling cleaning in the semiconductor cleaning process, since the cleaning of the wafer back surface 6b uses a liquid that does not generate heat by reacting with water, the wafer back surface without deteriorating apparatus parts such as nozzles. The contamination of 6b can be removed. Further, by using the liquid, the contamination level of the wafer back surface 6b can be further reduced.

  Further, when the wafer back surface 6b is cleaned, the chemical solution used for the wafer back surface processing wraps around the wafer surface 6a by covering the wafer surface 6a with an inert liquid such as water or an inert gas such as N2 gas. The element formed on the wafer surface 6a is not oxidized. As a result, it is possible to improve the yield rate of semiconductor devices and reduce the frequency of maintenance of the processing chamber itself, for example, the frequency of replacement of components such as nozzles.

  Next, based on an Example, this invention is explained in full detail. As the cleaning apparatus, the single wafer cleaning apparatus 1 having the wafer rotation mechanism shown in FIG. 1 was used.

[Example 1]
In step 1, a semiconductor wafer to be resist-removed and cleaned, that is, a semiconductor wafer 6 on which a resist film is formed on the surface 6a is set so as to be supported by the wafer support member 4 in the apparatus main body. While this semiconductor wafer is rotated at 200 rpm to 1000 rpm, an SC1 solution (NH ₄ OH / H ₂ O ₂ / H ₂ O) is supplied to the wafer back surface 6b through the lower nozzle 7 so that the resist or the like adhered to the wafer back surface 6b Remove organic contamination. At this time, the wafer surface 6a is covered with water or an inert gas such as nitrogen gas (N ₂ gas) so that the SC1 solution does not enter the wafer surface 6a.
In the next step 2, while rotating the semiconductor wafer 6 at 10 rpm to 2000 rpm, an SPM solution (H ₂ SO ₄ / H ₂ O ₂ ) is supplied to the wafer surface 6a through the upper nozzle 5A to resist the film on the wafer surface 6a. Remove.
In the next step 3, the SC1 solution is supplied to the wafer surface 6a and the wafer back surface 6b through the nozzles 5A and 7 respectively while rotating the semiconductor wafer 6 at 200 rpm to 1000 rpm, and the sulfuric acid and resist remaining on the wafer surface 6a are removed. Further, sulfuric acid marks and resist contamination adhering to the wafer back surface 6b are removed.
In the next step 4, while the semiconductor wafer 6 is rotated at 200 rpm to 1000 rpm, a rinsing liquid such as pure water, warm pure water or dilute hydrogen chloride (HCl) aqueous solution is supplied to the wafer front surface 6 a and the wafer back surface 6 b through the nozzles 5 B and 7. And rinse.
In the next step 5, the rinsing liquid is shaken and dried while rotating the semiconductor wafer 6 at 1500 rpm to 3000 rpm, and the cleaning process is completed.

[Example 2]
In Step 3 of Example 1, the SC1 solution is not supplied to the wafer back surface 6b, but the SC1 solution is supplied only to the wafer front surface 6a. Other steps 1, 2, 4, and 5 are the same as those in the first embodiment. In this way, it is also possible to supply the SC1 solution only to the wafer surface 6a in step 3. However, in Example 2, there is a possibility that contamination such as sulfuric acid marks may remain on the wafer back surface 6b.

[Example 3]
In Step 3 of Example 1, the SC1 solution is supplied to the wafer back surface 6b, and water or an inert gas such as nitrogen gas (N ₂ gas) is supplied to the wafer front surface 6a. Other steps 1, 2, 4, and 5 are the same as those in the first embodiment. In this way, it is also possible to supply water or nitrogen gas to the wafer surface 6a in step 3. In Example 3, although it is effective in the process which wants to suppress the oxidation of the wafer surface 6a, the contamination of the wafer surface 6a may not be completely removed.

[Example 4]
Step 3 of Example 1 is omitted. Other steps 1, 2, 4, and 5 are the same as those in the first embodiment. In this way, step 3 can be omitted. However, since there is a possibility that the treatment traces may be contaminated by the SPM solution, it is preferable to use warm pure water or diluted hydrogen chloride (HCl) water for the rinsing process in this case.

[Example 5]
In step 1, a semiconductor wafer to be resist-removed and cleaned, that is, a semiconductor wafer 6 on which a resist film is formed on the surface 6a is set so as to be supported by the wafer support member 4 in the apparatus main body. While rotating the semiconductor wafer 6 at 10 rpm to 2000 rpm, an SPC solution (H ₂ SO ₄ / H ₂ O ₂ ) is supplied to the wafer surface 6a through the upper nozzle 5A, and the resist film on the wafer surface 6a is removed.
In the next step 2, the SC1 solution is supplied to the wafer surface 6a and the wafer back surface 6b through the nozzles 5A and 7 while rotating the semiconductor wafer 6 at 200 rpm to 1000 rpm, and the sulfuric acid and resist remaining on the wafer surface 6a are removed. Resist contamination and the like attached to the wafer back surface 6b are removed.
In the next step 3, while the semiconductor wafer 6 is rotated at 200 rpm to 1000 rpm, a rinsing liquid such as pure water, hot pure water or dilute hydrogen chloride (HCl) aqueous solution is supplied to the wafer front surface 6 a and the wafer back surface 6 b through the nozzles 5 B and 7. And rinse.
In the next step 4, the rinsing liquid is shaken and dried while rotating the semiconductor wafer 6 at 1500 rpm to 3000 rpm, and the cleaning process is completed.

[Example 6]
In Step 2 of Example 5, the SC1 solution is supplied to the wafer back surface 6b, and water or an inert gas such as nitrogen gas (N ₂ gas) is supplied to the wafer front surface 6a. Other steps 1, 3, and 4 are the same as those in the fifth embodiment. Thus, in step 2, it is possible to cover the wafer front surface 6a with water or N2 gas and clean the wafer back surface 6b with the SC1 solution. In Example 6, contamination such as sulfuric acid marks may remain on the wafer surface 6a.

[Comparative Example 1]
In step 1, a semiconductor wafer to be resist-removed and cleaned, that is, a semiconductor wafer 6 on which a resist film is formed on the surface 6a is set so as to be supported by the wafer support member 4 in the apparatus main body. While rotating the semiconductor wafer 6 at 10 rpm to 2000 rpm, the SPM solution is supplied to the wafer front surface 6a and the wafer back surface 6b through the nozzles 5A and 7, respectively, and the resist film on the wafer front surface 6a is removed and attached to the wafer back surface 6b. Remove organic contamination such as resist.
In the next step 2, while rotating the semiconductor wafer 6 at 200 rpm to 1000 rpm, the SC1 solution is supplied to the wafer surface 6a through the upper nozzle 5A to remove sulfuric acid, resist, etc. remaining on the wafer surface 6a.
In the next step 3, while the semiconductor wafer 6 is rotated at 200 rpm to 1000 rpm, a rinsing liquid such as pure water, warm pure water or dilute hydrogen chloride (HCl) aqueous solution is supplied to the wafer front surface 6 a and the wafer back surface 6 b through the nozzles 5 B and 7. And rinse.
In the next step 4, the rinsing liquid is shaken and dried while rotating the semiconductor wafer 6 at 1500 rpm to 3000 rpm, and the cleaning process is completed.

[Comparative Example 2]
Step 2 of Comparative Example 1 is omitted. Other steps 1, 3, and 4 are the same as those in Comparative Example 1.

  Table 1 shows the results of evaluating the wafer back surface decontamination state and the state of apparatus parts such as nozzles for each of Examples 1 to 6 and Comparative Examples 1 and 2 described above. In the evaluation in Table 1, ◎ is very good, ○ is good, and Δ is slightly good.

According to Table 1, in each of the first to sixth embodiments, the contamination removal of the wafer front surface 6a and the wafer back surface 6b is satisfactorily performed, and deterioration of apparatus parts such as the cleaning nozzle 7 on the wafer back surface 6b is avoided. Can be confirmed. And as a resist peeling process, there exist a case of FIG.4 and FIG.5, for example. In the semiconductor wafer 6 of FIG. 4, the silicon oxide film 12 is formed on the surface of the silicon substrate 11, and the silicon oxide film 12 is patterned by etching through the resist mask 13. As the resist stripping process on the semiconductor wafer 6 from which a part of the silicon substrate 11 is exposed, the wafer back surface 6b is covered with a liquid or gas that does not affect elements on the surface of the exposed silicon substrate 11 and the wafer back surface 6b is covered. The method of Example 6 for washing with the SC1 solution may be used.
In the semiconductor wafer 6 of FIG. 5, a silicon nitride film 14 and a silicon oxide film 12 are stacked on the surface of the silicon substrate 11, and the silicon oxide film 12 is patterned by etching through a resist mask 13. As the resist stripping process in the semiconductor wafer 6 where the silicon substrate 11 is not exposed by the silicon nitride film 14, the wafer surface 6a is protected by the silicon nitride film 14, and therefore, the method of Example 5 can be used. Therefore, the resist stripping method can be selected according to the surface state of the semiconductor wafer 6.

  Further, as in the fourth embodiment, the sixth embodiment is more preferable with respect to the contamination removal of the wafer back surface 6b than the cleaning with the SC1 solution before the SPM solution cleaning. Actually, in Example 4 in which the SC1 solution treatment of the wafer back surface 6b was performed before the SPM solution treatment of the wafer surface 6a, the residual contamination of the wafer back surface 6b is in the state shown in FIG. In the case of Example 6 in which the SC1 solution treatment of the wafer back surface 6b was performed after the SPM solution treatment of FIG. 3, the residual contamination was in the state shown in FIG. 3, the residual number of contaminants 16 was completely different, and Example 6 (see FIG. 3). ) Is less.

[Example 7]
In Examples 1 to 6 in Table 1, the SC1 solution was used as the chemical solution for wafer backside cleaning, but instead of this SC1 solution, a solution made of diluted ammonia water, which is an alkaline chemical solution, or a potassium hydroxide solution, an acid type solution SC2 solution (HCl / H ₂ O ₂ / H ₂ O), FHPM solution (HF / HCl / H ₂ O ₂ / H ₂ O), and FPM solution (HF / H ₂ O ₂ / H ₂ O) which are chemicals The semiconductor wafer was cleaned by the same cleaning method as in Examples 1 to 6 for these chemical solutions. Also when the chemical | medical solution concerning wafer back surface washing | cleaning was used, the result similar to Examples 1-6 was obtained.

It is a schematic block diagram of the single wafer type washing apparatus applied to the washing method of the present invention. FIG. 6 is an explanatory view showing a contamination remaining state after cleaning the wafer back surface of Example 4; It is explanatory drawing which shows the contamination residual state after the washing | cleaning of the wafer back surface of Example 6. FIG. It is sectional drawing which shows an example of the cross-section of the semiconductor wafer which should carry out resist peeling cleaning. It is sectional drawing which shows the other example of the cross-section of the semiconductor wafer which should carry out resist peeling cleaning.

Explanation of symbols

  1 .... Single wafer cleaning device 2 .... Rotary shaft 3 .... Rotating substrate 4 .... Wafer support member 5 [5A, 5B] ... Nozzle 6, ... Semiconductor wafer 6a ... Wafer surface, 6b .. backside of wafer, 7 .. nozzle, 11 .. silicon substrate, 12 .. silicon oxide film, 13 .. resist mask, 14 .. silicon nitride film, 16.

Claims (7)

When performing resist removal cleaning of semiconductor wafers with a single wafer cleaning device,
A method for cleaning a semiconductor wafer, comprising cleaning the back surface of the wafer using a chemical solution that does not generate heat when mixed with water. The method for cleaning a semiconductor wafer according to claim 1, wherein a chemical solution capable of removing organic contamination is used as the chemical solution. The method for cleaning a semiconductor wafer according to claim 1, wherein an alkaline chemical solution is used as the chemical solution. 4. The method for cleaning a semiconductor wafer according to claim 3, wherein the alkaline chemical solution is a solution obtained by mixing ammonia water, hydrogen peroxide water, and water, a solution comprising diluted ammonia water, or a potassium hydroxide solution. . The method for cleaning a semiconductor wafer according to claim 1, wherein an acid-based chemical solution is used as the chemical solution. The acid chemical solution is a solution in which chlorine, hydrogen peroxide solution and water are mixed, a solution in which hydrogen fluoride, hydrogen chloride, hydrogen peroxide solution and water are mixed, or hydrogen fluoride, hydrogen peroxide solution and water. The method for cleaning a semiconductor wafer according to claim 5, wherein the solution is a mixed solution. The method for cleaning a semiconductor wafer according to claim 1, wherein the wafer surface is covered with an inert liquid or gas during the chemical treatment.

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