A wafer processing method

Abstract

The application provides a wafer processing method, which comprises the following steps: providing a wafer after chemical mechanical polishing; performing first particle cleaning on the wafer, wherein the cleaning solution used in the first particle cleaning comprises a hydrofluoric acid solution, a hydrochloric acid solution, a sulfuric acid solution or a citric acid solution; and performing second particle cleaning on the wafer, wherein the cleaning solution used in the second particle cleaning comprises a mixed solution of an ammonia solution and a hydrogen peroxide solution. The wafer surface metal concentration is reduced through the first particle cleaning, the cleaning effect of the second particle cleaning is improved, the residual pollution particles on the wafer surface after cleaning are reduced, and the yield of the wafer is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and more specifically to a wafer processing method. Background Technology

[0002] Chemical-Mechanical Polishing (CMP), also known as Chemical-Mechanical Planarization, is a semiconductor device manufacturing process used to planarize wafers or other substrate materials during processing. The basic principle involves rotating the workpiece relative to a polishing pad under pressure and in the presence of a polishing slurry (a mixture of ultrafine abrasive particles, chemical oxidants, organic matter, and liquid media). The mechanical abrasion of the abrasive particles and the corrosive action of the chemical oxidants remove material from the workpiece surface, resulting in a smooth surface. However, during CMP polishing, a large number of fine abrasive particles and chemical additives in the polishing slurry, as well as debris shed from wafer wear, may adhere to the wafer surface. Common contaminants on wafers after polishing include metal ions, organic compounds, or abrasive particles.

[0003] In the semiconductor manufacturing industry, chemical cleaning refers to the process of removing various harmful impurities adsorbed on the surfaces of semiconductors, metal materials, and tools. Without an effective cleaning procedure to remove these contaminants, subsequent processes will be affected, and the yield and reliability of components will be reduced. Therefore, after chemical mechanical polishing (CMP), it is essential to remove residual metal ions, abrasive particles, and organic matter from the wafer surface to reduce surface defects. Current technology utilizes the weak alkalinity of ammonia to activate the surface of silicon wafers and abrasive particles, causing mutual repulsion between the wafer surface and the abrasive particles. Simultaneously, ammonia forms soluble complexes with some metal ions, removing insoluble metals. This method is effective for removing copper, but it is difficult to remove iron, aluminum (which exists in forms including metal oxides and ions), thus reducing wafer yield. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the large number of residual particles after existing wafer cleaning leads to a decrease in yield, and thus to provide a wafer processing method.

[0005] The present invention provides a wafer processing method, comprising: providing a wafer after chemical mechanical polishing; performing a first particulate cleaning on the wafer, wherein the cleaning solution used for the first particulate cleaning includes hydrofluoric acid solution, hydrochloric acid solution, sulfuric acid solution or citric acid solution; and performing a second particulate cleaning on the wafer, wherein the cleaning solution used for the second particulate cleaning includes a mixed solution of ammonia solution and hydrogen peroxide solution.

[0006] Optionally, the concentration of the hydrofluoric acid solution in the first particulate matter cleaning process is 4.5% to 5.5%, the concentration of the hydrochloric acid solution in the first particulate matter cleaning process is 5% to 6%, the concentration of the sulfuric acid solution in the first particulate matter cleaning process is 5.5% to 6.5%, the concentration of the hydrogen peroxide solution in the first particulate matter cleaning process is 15% to 20%, and the concentration of the citric acid solution in the first particulate matter cleaning process is 20% to 50%.

[0007] Optionally, the washing time for the first particulate matter is 20 to 30 seconds.

[0008] Optionally, the flow rate of the cleaning fluid used for the first particulate matter cleaning is 100 ml / min to 200 ml / min.

[0009] Optionally, a hydrogen peroxide solution with a concentration of 15% to 20% may be added to the cleaning solution used for the first particulate matter cleaning.

[0010] Optionally, the concentration of the ammonia solution in the second particulate matter cleaning process is 12% to 22%, the concentration of the hydrogen peroxide solution in the second particulate matter cleaning process is 15% to 20%, and the volume ratio of the ammonia solution to the hydrogen peroxide solution in the second particulate matter cleaning process is 3.5:1 to 5:1.

[0011] Optionally, the second particulate matter washing time is 25 to 35 seconds.

[0012] Optionally, the first particulate matter cleaning method includes any one or a combination of two or more of rotary brushing, spraying, or vibration cleaning; the second particulate matter cleaning method includes any one or a combination of two or more of rotary brushing, spraying, or vibration cleaning.

[0013] Optionally, the vibration cleaning includes megasonic cleaning.

[0014] Optionally, the frequency of the megaacoustic cleaning is 450 Hz to 550 Hz.

[0015] Optionally, after performing a second particulate cleaning on the wafer, the process further includes performing a first brushing on the wafer, wherein the cleaning solution used for the first brushing includes a hydrofluoric acid solution.

[0016] Optionally, the concentration of the hydrofluoric acid solution during the first scrubbing process is 4.5% to 5.5%.

[0017] Optionally, the first scrubbing time is 15 to 25 seconds.

[0018] Optionally, after the wafer is first washed, the method further includes: performing a second wash on the wafer, wherein the cleaning solution used in the second wash includes an ammonia solution.

[0019] Optionally, the concentration of the ammonia solution in the second scrubbing process is 12% to 22%.

[0020] Optionally, the second scrubbing time is 25 to 35 seconds.

[0021] Optionally, after the wafer undergoes the first particulate cleaning and before the wafer undergoes the second particulate cleaning, the method further includes: performing a first deionized water cleaning on the wafer.

[0022] Optionally, the first deionized water rinsing time is 15 to 20 seconds.

[0023] Optionally, after the wafer undergoes the first particulate cleaning and before the wafer undergoes the first brushing, the process further includes: performing a second deionized water cleaning on the wafer.

[0024] Optionally, the second deionized water rinsing time is 20 to 25 seconds.

[0025] Optionally, after the first brushing of the wafer and before the second brushing of the wafer, the method further includes: performing a third deionized water cleaning on the wafer.

[0026] Optionally, the third deionized water rinsing time is 10 to 25 seconds.

[0027] Optionally, after the wafer is subjected to a second brushing, the process further includes: performing a fourth deionized water cleaning on the wafer.

[0028] Optionally, the fourth deionized water rinsing time is 10 to 25 seconds.

[0029] Optionally, after performing a fourth deionized water cleaning on the wafer, the wafer is dried.

[0030] Optionally, the drying process includes nitrogen blowing and / or rotary spin drying.

[0031] The technical solution of this invention has the following advantages:

[0032] The wafer processing method of the present invention includes: providing a wafer after chemical mechanical polishing (CMP); performing a first particulate cleaning on the wafer, wherein the cleaning solution used for the first particulate cleaning includes hydrofluoric acid solution, hydrochloric acid solution, sulfuric acid solution, or citric acid solution; and performing a second particulate cleaning on the wafer, wherein the cleaning solution used for the second particulate cleaning includes a mixed solution of ammonia solution and hydrogen peroxide solution. The cations in the CMP polishing solution mainly include aluminum ions, boron ions, calcium ions, iron ions, and potassium ions, and the polishing solution is weakly alkaline. During the polishing process, some cations form insoluble metal oxides, such as iron oxide, aluminum oxide, and calcium oxide, which remain on the surface of the wafer after CMP polishing. The first particulate cleaning can dissolve and remove these alkaline oxides. The second particulate cleaning utilizes the weak alkalinity of the ammonia solution to activate the wafer and the surface of contaminant particles, causing mutual repulsion between the wafer surface and the contaminant particles, making the contaminant particles easier to remove. Furthermore, the ammonia solution can form soluble complexes with some metal ions in the contaminant particles, achieving the effect of removing contaminant particles. Furthermore, hydrogen peroxide oxidizes the wafer surface, and then an ammonia solution micro-etches the oxide layer to remove contaminant particles embedded in the wafer surface. These contaminant particles fall into the cleaning solution along with the oxide layer. Since the metal concentration on the wafer surface during the second particulate cleaning process is affected by the metal concentration in the cleaning solution, it is a dynamic equilibrium process of adsorption and desorption. The lower the metal concentration in the cleaning solution, the lower the metal concentration on the wafer surface. Therefore, reducing the metal concentration on the wafer surface through the first particulate cleaning can improve the cleaning effect of the second particulate cleaning, reduce the number of residual contaminant particles on the wafer surface after cleaning, and improve the wafer yield.

[0033] Furthermore, a 15%–20% hydrogen peroxide solution is added to the cleaning solution used for the first particulate cleaning. A suitable concentration of sulfuric acid solution combined with hydrogen peroxide solution can effectively remove residual organic matter on the wafer surface through an oxidation reaction. A suitable concentration of hydrogen fluoride solution combined with hydrogen peroxide solution can form a silicon dioxide layer on the wafer surface. Then, utilizing the characteristic that hydrogen fluoride solution easily dissolves silicon dioxide without reacting with it, the silicon dioxide layer is corroded away while simultaneously removing residual contaminant particles from the surface.

[0034] Furthermore, the vibration cleaning includes megasonic cleaning. Megasonic cleaning can remove particles larger than or equal to 0.2 micrometers, achieving good particle removal at room temperature while avoiding damage caused by ultrasonic cleaning of lenses.

[0035] Furthermore, after the second particulate cleaning of the wafer, the process further includes: performing a first brushing of the wafer, wherein the cleaning solution used for the first brushing includes a hydrofluoric acid solution. The hydrofluoric acid solution can completely remove the oxide layer formed during the second particulate cleaning without corroding the silicon wafer.

[0036] Furthermore, after the first rinsing of the wafer, the process further includes: performing a second rinsing of the wafer, wherein the cleaning solution used in the second rinsing includes an ammonia solution. The ammonia solution neutralizes any residual hydrofluoric acid solution from the first rinsing. Attached Figure Description

[0037] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 This is a schematic flowchart of the wafer processing method of the present invention;

[0039] Figure 2 This is a schematic diagram of the combination of the rotating brushing device and the spraying device in an embodiment of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] This embodiment provides a wafer processing method, such as... Figure 1 As shown, it includes the following steps:

[0045] Step S1: Provide the wafer after chemical mechanical polishing;

[0046] Step S2: Perform a first particulate cleaning on the wafer. The cleaning solution used for the first particulate cleaning includes hydrofluoric acid solution, hydrochloric acid solution, sulfuric acid solution or citric acid solution.

[0047] Step S3: Perform a second particulate cleaning on the wafer. The cleaning solution used for the second particulate cleaning includes a mixture of ammonia solution and hydrogen peroxide solution.

[0048] The cations in the polishing slurry of chemical mechanical polishing (CMP) mainly include aluminum, boron, calcium, iron, and potassium ions, and the slurry is weakly alkaline. During the polishing process, some cations form insoluble metal oxides, such as iron oxide, aluminum oxide, and calcium oxide, which remain on the wafer surface after CMP. The first particulate cleaning process dissolves and removes these alkaline oxides. The second particulate cleaning process utilizes the weak alkalinity of ammonia solution to activate the wafer and contaminant surface, creating mutual repulsion between the wafer surface and the contaminants, making the contaminants easier to remove. Furthermore, the ammonia solution can form soluble complexes with some metal ions in the contaminants, achieving the effect of removing contaminants. In addition, hydrogen peroxide oxidizes the wafer surface, and then the ammonia solution micro-etches the oxide layer, removing contaminants embedded in the wafer surface. These contaminants fall into the cleaning solution along with the oxide layer. Because the metal concentration on the wafer surface during the second particulate cleaning process is affected by the metal concentration in the cleaning solution, it is a dynamic equilibrium process of adsorption and desorption; the lower the metal concentration in the cleaning solution, the lower the metal concentration on the wafer surface. Therefore, reducing the metal concentration on the wafer surface through the first particulate cleaning can improve the cleaning effect of the second particulate cleaning, reduce the amount of contaminant particles remaining on the wafer surface after cleaning, and improve the wafer yield.

[0049] In one embodiment, the concentration of the hydrofluoric acid solution during the first particulate cleaning process is 4.5% to 5.5%, for example, 4.5%, 5%, or 5.5%; the concentration of the hydrochloric acid solution during the first particulate cleaning process is 5% to 6%, for example, 5%, 5.5%, or 6%; the concentration of the sulfuric acid solution during the first particulate cleaning process is 5.5% to 6.5%, for example, 5.5%, 6%, or 6.5%; the concentration of the hydrogen peroxide solution during the first particulate cleaning process is 15% to 20%, for example, 15%, 16%, 17%, 18%, 19%, or 20%; and the concentration of the citric acid solution during the first particulate cleaning process is 20% to 50%, for example, 20%, 30%, 40%, or 50%. Specifically, the first particulate cleaning time is 20 seconds to 30 seconds, for example, 20 seconds, 25 seconds, or 30 seconds. Specifically, the flow rate of the cleaning solution used for the first particulate matter cleaning is 100 ml / min to 200 ml / min, for example, 100 ml / min, 130 ml / min, 160 ml / min, or 200 ml / min. By adjusting the concentration, flow rate, and cleaning time of the cleaning solution during the first particulate matter cleaning process, the alkaline oxides on the wafer surface can be dissolved and removed.

[0050] In one embodiment, the first particulate matter cleaning method includes any one or a combination of two or more of rotary brushing, spraying, or vibration cleaning. In a specific embodiment, such as... Figure 2 As shown, the first particulate matter cleaning method involves clamping the wafer with a cleaning brush 1 and rotating it mechanically. At the same time, the wafer also rotates through a roller 2. The spray cleaning liquid cleans the metal ions and other residues on the wafer surface. The spray equipment can precisely adjust the flow rate of the cleaning liquid. At the same time, the liquid sprayed onto the wafer has a certain impact on the wafer surface. Combined with the mechanical rotation of the brush, a better cleaning effect can be obtained.

[0051] In this embodiment, the cleaning solution used for the first particulate matter cleaning contains a hydrogen peroxide solution with a concentration of 15% to 20%, such as 15%, 16%, 17%, 18%, 19%, or 20%. A suitable concentration of sulfuric acid solution combined with hydrogen peroxide solution can effectively remove residual organic matter on the wafer surface through an oxidation reaction. A suitable concentration of hydrogen fluoride solution combined with hydrogen peroxide solution can form a silicon dioxide layer on the wafer surface. Then, utilizing the characteristic that hydrogen fluoride solution easily dissolves silicon dioxide without reacting with it, the silicon dioxide layer is etched away while simultaneously removing residual particles from the surface.

[0052] In one embodiment, after the wafer undergoes a first particulate cleaning and before undergoing a second particulate cleaning, the process further includes performing a first deionized water cleaning on the wafer. The first deionized water cleaning removes residual waste liquid from the wafer surface after the first particulate cleaning. Specifically, the first deionized water cleaning takes 15 to 20 seconds, for example, 15 seconds, 17 seconds, or 20 seconds.

[0053] In one embodiment, the concentration of the ammonia solution in the second particulate matter cleaning process is 12% to 22%, for example, 12%, 15%, 18%, 20%, or 22%; the concentration of the hydrogen peroxide solution in the second particulate matter cleaning process is 15% to 20%, for example, 15%, 16%, 17%, 18%, 19%, or 20%; and the volume ratio of the ammonia solution to the hydrogen peroxide solution in the second particulate matter cleaning process is 3.5:1 to 5:1, for example, 3.5:1, 4:1, 4.5:1, or 5:1. Specifically, the cleaning time for the second particulate matter is 25 seconds to 35 seconds, for example, 25 seconds, 30 seconds, or 35 seconds.

[0054] In one embodiment, the second particulate cleaning method includes any one or a combination of two or more of rotary brushing, spraying, or vibration cleaning. Specifically, the vibration cleaning includes megasonic cleaning. Megasonic cleaning can remove particles larger than or equal to 0.2 micrometers, achieving good particle removal at room temperature while avoiding damage caused by ultrasonic cleaning of lenses. Specifically, the frequency of the megasonic cleaning is 450 Hz to 550 Hz, for example, 450 Hz, 480 Hz, or 500 Hz.

[0055] In one embodiment, after the wafer undergoes a first particulate cleaning and before the wafer undergoes a first brushing, the process further includes: performing a second deionized water cleaning on the wafer. The second deionized water cleaning removes residual waste liquid from the wafer surface after the second particulate cleaning. Specifically, the second deionized water cleaning takes 20 to 25 seconds, for example, 20 seconds, 22 seconds, or 25 seconds.

[0056] In this embodiment, after the wafer undergoes a second particulate cleaning, the process further includes a first brushing of the wafer, wherein the cleaning solution used in the first brushing includes a hydrofluoric acid solution. The hydrofluoric acid solution can completely remove the oxide layer formed during the second particulate cleaning without corroding the silicon wafer. Since only a portion of the oxide layer formed by the hydrogen peroxide solution oxidation during the second particulate cleaning is removed by the ammonia solution, the residual oxide layer has a significantly different etching rate compared to the silicon wafer in subsequent etching processes. Therefore, even a thin residual oxide layer can significantly impact subsequent etching processes. Furthermore, during the second particulate cleaning process, the selective corrosion by the ammonia solution results in uneven oxide layer thickness on the wafer surface after cleaning, leading to unstable linewidths in subsequent etching processes. This can also cause significant differences in critical dimensions (CD) between different wafers and between different locations on the same wafer, affecting the overall yield and performance of the wafer. Specifically, the concentration of the hydrofluoric acid solution in the first brushing process is 4.5% to 5.5%, for example, 4.5%, 5%, or 5.5%. Specifically, the first scrubbing time is 15 to 25 seconds, for example, 15 seconds, 20 seconds or 25 seconds.

[0057] In one embodiment, after the first brushing of the wafer and before the second brushing, the method further includes a third deionized water cleaning of the wafer. The third deionized water cleaning removes residual waste liquid from the wafer surface after the first brushing; this waste liquid is primarily hydrofluoric acid and fluorosilicic acid. Specifically, the third deionized water cleaning time is 10 to 15 seconds, for example, 10 seconds, 12 seconds, or 15 seconds.

[0058] In this embodiment, after the wafer undergoes a first rinsing, the process further includes a second rinsing of the wafer. The cleaning solution used in the second rinsing includes an ammonia solution. The ammonia solution neutralizes any residual hydrofluoric acid solution from the first rinsing process. Specifically, the concentration of the ammonia solution used in the second rinsing process is 12% to 22%, for example, 12%, 15%, 18%, 20%, or 22%. Specifically, the duration of the second rinsing is 25 to 35 seconds, for example, 25 seconds, 30 seconds, or 35 seconds.

[0059] In this embodiment, after the second brushing of the wafer, the process further includes a fourth deionized water cleaning. The fourth deionized water cleaning removes residual waste liquid from the wafer surface after the second brushing; this waste liquid is primarily ammonia. Specifically, the fourth deionized water cleaning takes 10 to 15 seconds, for example, 10 seconds, 12 seconds, or 15 seconds.

[0060] In this embodiment, after the wafer undergoes a fourth deionized water cleaning, it is dried. Specifically, the drying process includes nitrogen blowing and / or spin drying. After spin drying, the wafer is returned to the wafer cassette.

[0061] The wafer processing method in this embodiment is applicable to 8-inch or 12-inch chemical mechanical polishing machines and is suitable for various process requirements, including copper process, oxide process, tungsten process, polysilicon process, shallow trench isolation (STI), etc.

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method of processing a wafer, characterized by, The application relates to a chemical mechanical polishing method for a wafer. The wafer is a silicon wafer. The wafer is subjected to first particle cleaning, the cleaning liquid used in the first particle cleaning comprises a hydrofluoric acid solution; the cleaning liquid used in the first particle cleaning also comprises a hydrogen peroxide solution; the hydrogen peroxide solution is suitable for forming a silicon dioxide layer on the wafer surface in cooperation with the hydrofluoric acid solution, and the hydrofluoric acid solution is used to etch away the silicon dioxide layer and remove the residual particles on the surface; the concentration of the hydrofluoric acid solution in the first particle cleaning process is 4.5%-5.5%, the concentration of the hydrogen peroxide solution in the first particle cleaning process is 15%-20%, the first particle cleaning time is 20-30 seconds, and the flow rate of the cleaning liquid used in the first particle cleaning is 100-200 ml / min. The wafer is subjected to second particle cleaning, the cleaning liquid used in the second particle cleaning comprises a mixed solution of an ammonia solution and a hydrogen peroxide solution; the hydrogen peroxide solution is suitable for forming an oxidation layer on the wafer surface, and the ammonia solution is suitable for micro-etching the oxidation layer and removing the contaminated particles embedded in the wafer surface. After the second particle cleaning, the wafer is subjected to first brushing, the cleaning liquid used in the first brushing comprises a hydrofluoric acid solution; the hydrofluoric acid solution is suitable for completely removing the oxidation layer formed in the second particle cleaning; the concentration of the hydrofluoric acid solution in the first brushing process is 4.5%-5.5%, and the first brushing time is 15-25 seconds. After the first brushing, the wafer is subjected to second brushing, the cleaning liquid used in the second brushing comprises an ammonia solution; the ammonia solution is suitable for neutralizing the residual hydrofluoric acid solution in the first brushing process; the concentration of the ammonia solution in the second brushing process is 12%-22%, and the second brushing time is 25-35 seconds. The cleaning liquid used in the first particle cleaning is added with a hydrogen peroxide solution with a concentration of 15%-20%.

2. The wafer processing method according to claim 1, wherein In the second particle cleaning process, the concentration of the ammonia solution is 12%-22%, the concentration of the hydrogen peroxide solution is 15%-20%, and the volume ratio of the ammonia solution to the hydrogen peroxide solution is 3.5:1-5:

1.

3. The wafer processing method according to claim 1, wherein The second particle cleaning time is 25-35 seconds. The first particle cleaning mode comprises any one or a combination of two or more of rotary brushing, spraying and vibration cleaning; the second particle cleaning mode comprises any one or a combination of two or more of rotary brushing, spraying and vibration cleaning.

4. The wafer processing method according to claim 1, wherein The vibration cleaning in the first particle cleaning and the vibration cleaning in the second particle cleaning both comprise megasonic cleaning; the frequency of the megasonic cleaning is 450-550 Hz. After the first particle cleaning and before the second particle cleaning, the wafer is subjected to first deionized water cleaning.

5. The wafer processing method according to claim 1, wherein The first deionized water cleaning time is 15-20 seconds. ​ 6. The wafer processing method of claim 1, wherein The method further comprises, after the second particle cleaning and before the first brush cleaning, performing a second deionized water cleaning on the wafer. The second deionized water cleaning is performed for 20-25 seconds.

7. The wafer processing method of claim 1, wherein The method further comprises, after the first brush cleaning and before the second brush cleaning, performing a third deionized water cleaning on the wafer. The third deionized water cleaning is performed for 10-15 seconds.

8. The wafer processing method of claim 1, wherein The method further comprises, after the second brush cleaning, performing a fourth deionized water cleaning on the wafer. The fourth deionized water cleaning is performed for 10-15 seconds.

9. The wafer processing method according to claim 8, wherein The method further comprises, after the fourth deionized water cleaning, drying the wafer. The drying process comprises nitrogen blowing and / or spin-drying.

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