Method for solving particle aggregation at polishing edge of wafer

Abstract

The invention discloses a method for solving wafer polishing edge particle aggregation, and belongs to the technical field of semiconductor manufacturing. The method comprises the following steps: before a wafer final polishing procedure is carried out, a wafer is sequentially and respectively soaked in an SC1 solution, an HF solution and an O3 aqueous solution to obtain a wafer with a hydrophilic surface, and then final polishing operation is carried out; wherein the treatment time of the wafer in the SC1 solution is 1-6 min, and the temperature of the SC1 solution is 30-70 DEG C; the treatment time of the wafer in the HF solution is 1-200 s; the treatment time of the wafer in the O3 aqueous solution is 1-200 s. According to the method, the surface state of the wafer before polishing is changed in a chemical mode, and the polishing solution can be completely cleaned in time after the wafer is polished, so that edge particle aggregation caused by the fact that the polishing solution cannot be cleaned in time in the polishing process is avoided. The method is wide in practicability, simple in technological process, short in treatment time, low in cost and good in application prospect.

Description

Technical Field

[0001] The invention relates to a method for solving the problem of particle aggregation at the polishing edge of a wafer, and belongs to the technical field of semiconductor manufacturing. Background Art

[0002] Semiconductor technology has developed rapidly in the past few decades. The size of silicon wafers has gradually increased from 50 mm to 300 mm, while the critical size is constantly shrinking. As the device size gradually decreases and the focal depth of optical lithography equipment decreases, the requirements of the integrated circuit manufacturing process for the silicon wafer surface are also increased to the nanometer level. The number and distribution of particles on the wafer surface will greatly affect the final yield.

[0003] After the final polishing, the wafer needs to be cleaned to remove the polishing liquid on the surface, and further remove the particles and metal on the surface. If the polishing liquid cannot be removed in time and comprehensively, it will micro-corrode the surface of the wafer, thus affecting the surface state of the wafer and easily causing local particle aggregation on the wafer. Summary of the invention

[0004] Based on the above problems existing in the prior art, the purpose of the present invention is to provide a method for solving the problem of particle aggregation at the polishing edge of the wafer. The method is used in the cleaning process before fine polishing to solve the problem of particle aggregation at the edge of the wafer caused by corrosion of the polishing liquid after polishing.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A method for solving the problem of particle aggregation at the polishing edge of a wafer, the method comprising: before performing a final polishing process of the wafer, immersing the wafer in an SC1 solution, an HF solution, and an O3 aqueous solution in sequence to obtain a wafer with a hydrophilic surface, and then performing a final polishing operation; wherein the processing time of the wafer in the SC1 solution is 1-6 min, and the temperature of the SC1 solution is 30-70° C.; the processing time of the wafer in the HF solution is 1-200 s; the processing time of the wafer in the O3 aqueous solution is 1-200 s, and the concentration of O3 in the O3 aqueous solution is 5-30 ppm.

[0006] According to the technical solution, three different solutions are used to treat the wafer before the final polishing operation. SC1 solution, hydrofluoric acid solution and ozone aqueous solution are used to treat the wafer in turn, and the wafer is finally immersed in O3 aqueous solution to make the surface of the wafer have a certain thickness of oxide film, instead of using SC1 to obtain the oxide film. The use of hydrofluoric acid solution and ozone aqueous solution can reduce the metal level on the surface of the wafer while obtaining the oxide film, thereby reducing the contamination of the metal to the fine polishing machine.

[0007] Furthermore, the wafers are washed with deionized water after being immersed in each solution. The final polishing operation is fine polishing, and the wafers are dried before the final polishing.

[0008] Preferably, the SC1 solution is a mixture of an ammonia solution, a hydrogen peroxide solution and water, and the volume ratio of the ammonia solution, the hydrogen peroxide solution and water is (0.5-10):1:(10-30). The mass percentage concentration of the ammonia solution is 20-37%; the mass percentage concentration of the hydrogen peroxide solution is 14-30%.

[0009] Preferably, the mass percentage concentration of the HF solution is 10-23%.

[0010] Preferably, the flow rate of the O3 aqueous solution is 5-30 L / min.

[0011] The technical solution provided by the embodiment of the present invention has the following advantages compared with the prior art: (1) The present invention changes the surface state of the wafer before polishing by chemical means, so that the polishing liquid of the wafer can be cleaned up in time and completely after polishing, thereby avoiding the edge particle aggregation caused by the inability to remove the polishing liquid in time during the polishing process.

[0012] (2) The method provided by the present invention has wide practicability and can be used in the cleaning process before fine polishing; the process flow is simple, the processing time is short, and the cost is low; at the same time, the damage to the wafer is small, and the metal content on the wafer surface is low, which can completely solve the problem of edge particle aggregation caused by the polishing process and improve the subsequent final cleaning effect, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a picture of the integrated output channel (DC) output of the SP5 XP wafer defect detector used in Example 1 to detect wafer edge particles.

[0014] Figure 2 This is a picture of the integrated output channel (DC) output of the SP5 XP wafer defect inspector used to detect wafer edge particles in the comparative example. DETAILED DESCRIPTION

[0015] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the scheme of the present invention will be further described below.

[0016] The method for solving the problem of particle aggregation at the polishing edge of a wafer provided by the present invention comprises: before polishing the wafer, immersing the wafer in an SC1 solution, an HF solution, and an O3 aqueous solution in sequence, specifically: immersing the wafer in an SC1 solution at 30-70° C. for 1-6 min, then taking it out and immersing it in an HF solution for 1-200 s, and finally immersing it in an O3 aqueous solution with an O3 concentration of 5-30 ppm and a flow rate of 5-30 L / min for 1-200 s to obtain a wafer with a hydrophilic surface, and then performing a final polishing operation after drying.

[0017] As a specific embodiment of the present invention, the SC1 solution is a mixture of an ammonia solution, a hydrogen peroxide solution and water, preferably a volume ratio of an ammonia solution, a hydrogen peroxide solution and water is (0.5-10):1:(10-30), such as 0.5:1:10, 10:1:10, 0.5:1:30, 10:1:30, etc. Wherein, the mass percentage concentration of the ammonia solution is 20-37%, such as 22%, 25%, 28%, 30%, 32%, 35%, etc. The mass percentage concentration of the hydrogen peroxide solution is 14-30%, such as 14%, 17%, 20%, 23%, 26%, 30%, etc.

[0018] As a specific implementation of the present invention, the processing time of the wafer in the SC1 solution is 1-6 min, for example, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, etc.

[0019] As a specific embodiment of the present invention, the mass percentage concentration of the hydrofluoric acid solution is 10-23%, for example, 10%, 13%, 16%, 20%, 23%, etc.

[0020] As a specific implementation of the present invention, the processing time of the wafer in the hydrofluoric acid solution is 1-200s, for example, 1s, 10s, 60s, 100s, 200s, etc.

[0021] As a specific embodiment of the present invention, the mass percentage concentration of the ozone aqueous solution is 5-30ppm, such as 5ppm, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, etc. The flow rate of the ozone aqueous solution is 5-30L / min, such as 5L / min, 10L / min, 15L / min, 20L / min, 30L / min, etc.

[0022] As a specific embodiment of the present invention, the processing time of the wafer in the ozone aqueous solution is 1-200s, for example, 1s, 10s, 60s, 100s, 200s, etc.

[0023] Example 1 The processing object involved in this embodiment is a 300 mm wafer, and the method used includes the following steps: (1) Mix 1.5 L of 37% ammonia water and 3 L of 30% hydrogen peroxide with 30 L of water to prepare SC1 solution.

[0024] (2) Place the wafer in a 30°C SC1 solution for 1 min, then wash with deionized water to remove the SC1 solution on the wafer surface.

[0025] (3) Then place the wafer in a 10% by mass HF solution for 1 min, and then wash it with deionized water to remove the HF solution on the surface of the wafer.

[0026] (4) Place the wafer in an O3 aqueous solution with a concentration of 5 ppm and a flow rate of 5 L / min for 10 s, and then wash it with deionized water to remove the O3 aqueous solution on the surface of the wafer.

[0027] (5) The processed wafer is dried and then fine-polished to obtain a polished wafer.

[0028] Example 2 The processing object involved in this embodiment is a 300 mm wafer, and the method used includes the following steps: (1) Mix 1.5 L of 22% ammonia water and 3 L of 14% hydrogen peroxide with 30 L of water to prepare SC1 solution.

[0029] (2) First, place the wafer in a 70°C SC1 solution for 6 min, and then wash it with deionized water to remove the SC1 solution on the wafer surface.

[0030] (3) The wafer is then placed in a 0.9% by mass HF solution for 6 minutes and then washed with deionized water to remove the HF solution on the surface of the wafer.

[0031] (4) Place the wafer in an O3 aqueous solution with a concentration of 25 ppm and a flow rate of 25 L / min for 100 s, and then wash it with deionized water to remove the O3 aqueous solution on the surface of the wafer.

[0032] (5) The processed wafer is dried and then fine-polished to obtain a polished wafer.

[0033] Comparative Example The difference between this comparative example and Example 1 is that in this comparative example, steps (3) and (4) are omitted.

[0034] Performance test 1: Surface morphology analysis Use SP5 XP wafer defect detector to detect particles on the edge of polished wafers. Figure 1 , Figure 2 The wafer edge detection results of the embodiment and the comparative example are shown respectively. The figure shows the output of the integrated output channel (DC) in the SP5 XP detection, and the particle size range corresponding to each color block is marked below the picture. By comparison, it can be seen that after the cleaning process of the present invention and then polishing, there is no aggregation of edge particles on the wafer surface.

[0035] Performance Test 2: Surface Metal Analysis ICP-MS was used to detect the metal on the surface of the wafers after cleaning and polishing in Example 1 and the comparative example. The results are shown in Table 1.

[0036] Table 1 Metal levels on the wafer surface after wafer cleaning and polishing in Example 1 and Comparative Example

[0037] It can be seen from Table 1 that the surface metal level of the wafer in the comparative example is worse than that in the embodiment.

[0038] In summary, it can be seen from the embodiments, comparative examples and performance test results that the method provided by the present invention can completely solve the problem of wafer edge aggregation, and within the preferred range of the present invention, the aggregation problem can be solved, and the metal level of the wafer before polishing can be reduced, reducing the pollution of the fine polishing machine during the processing.

Claims

1. A method for solving particle aggregation at the edge of a wafer polish, characterized in that: The method comprises: before the final polishing process of the wafer, immersing the wafer in SC1 solution, HF solution and O3 aqueous solution in sequence to obtain a wafer with a hydrophilic surface, and then performing the final polishing operation; wherein the processing time of the wafer in the SC1 solution is 1-6 min, and the temperature of the SC1 solution is 30-70°C; the processing time of the wafer in the HF solution is 1-200 s; and the processing time of the wafer in the O3 aqueous solution is 1-200 s.

2. The method according to claim 1, characterized in that After the wafers were immersed in each solution, they were washed with deionized water.

3. The method according to claim 2, characterized in that The final polishing operation is fine polishing, and the wafer is dried before the final polishing.

4. The method according to any one of claims 1 to 3, characterized in that The SC1 solution is a mixture of an ammonia solution, a hydrogen peroxide solution and water, and the volume ratio of the ammonia solution, the hydrogen peroxide solution and water is (0.5-10):1:(10-30).

5. The method according to claim 4, characterized in that The mass percentage concentration of the ammonia solution is 20-37%; the mass percentage concentration of the hydrogen peroxide solution is 14-30%.

6. The method according to any one of claims 1 to 3, characterized in that The mass percentage concentration of the HF solution is 10-23%.

7. The method according to any one of claims 1 to 3, characterized in that The concentration of O3 in the O3 aqueous solution is 5-30 ppm, and the flow rate of the O3 aqueous solution is 5-30 L / min.

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