Technological method for reducing scratches on polished surface

Abstract

The invention relates to a process method for reducing scratches on a polished surface, which belongs to the technical field of silicon wafer processing and comprises the following operation steps: step 1, taking a line body with crystals in a polishing head and a pipeline for experiment; 2, 200 light boron-doped silicon wafers are taken to be subjected to removal comparison before and after crystallization and divided into two groups, and each group comprises 100 silicon wafers; and thirdly, 100 pieces in the first group are normally attached and polished, and SP1 test statistics is conducted on the scratch occurrence rate after dewaxing and final cleaning. And 4, soaking the pipeline and the polishing head in 48% KOH and water in a ratio of 1: 2 for 4-6 hours in the second group. And 5, adhering and polishing the treated 100 pieces in the second group, dewaxing, finally cleaning, and carrying out SP1 test to count the scratch occurrence rate. And 6, comparing the scratch incidence rates of the polished surface of the silicon wafer twice. The method has the advantages of convenient operation and good operation stability. The problem that the surface of the silicon wafer is easily scratched in the polishing process is solved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon wafer processing, and in particular to a process method for reducing scratches on a polished surface. Background Art

[0002] At present, the semiconductor IC industry has entered the era of large-scale and ultra-large-scale integrated circuits. The characteristics of integrated circuits are developing towards nanometer sizes, which requires integrated circuits to use single-crystal silicon wafers or epitaxial silicon wafers with increasingly higher surface quality. In order to ensure qualified product performance during the manufacturing process of integrated circuit components, the surface of the front-end product wafer is required to be free of surface damage and sub-damage. Mechanical chemical polishing without surface and sub-surface damage is the key point of single-crystal silicon polishing technology, and is also the key to the stable operation of integrated circuit electronic components in the electronics industry and the continuous development of smaller line width processes.

[0003] 8-inch silicon wafers are mostly polished in wax-coated multi-wafer mode. Polishing is divided into three processes: rough polishing, medium polishing, and fine polishing. Rough polishing is mainly used to remove damage to the previous material and ensure that the silicon wafer has a good flatness. Medium polishing is mainly used to ensure that the silicon wafer has a low roughness and high-quality silicon wafer surface. The main removal amount is concentrated in rough polishing, so a high-concentration, high-particle-size, and high-pH polishing liquid is required. The reaction mainly relies on potassium hydroxide to oxidize the silicon wafer surface.

[0004] When the chemical action is stronger than the mechanical action, it will lead to excessive corrosion of the surface. When the mechanical action is stronger than the chemical action, the incidence of scratches will rise sharply. Therefore, a suitable pH and polishing fluid are important factors in reducing scratches. When the alkali solution and Si are not fully reacted and removed in time, crystals will be produced and remain in the pipes, cloth, and liquid, which will also cause scratches on the polished surface of the silicon wafer. Appropriate liquid to remove crystals is also an important measure to prevent scratches. Summary of the invention

[0005] The present invention mainly solves the deficiencies in the prior art and provides a process for reducing scratches on the polished surface, which has the advantages of convenient operation and good running stability, and solves the problem that the surface of the silicon wafer is easily scratched during polishing.

[0006] The above technical problems of the present invention are mainly solved by the following technical solutions: A process for reducing scratches on a polished surface comprises the following steps: Step 1: Take a wire with crystals on the polishing head and pipe for experiment.

[0007] Step 2: Take 200 lightly doped borosilicate wafers and compare them before and after crystallization, and divide them into 2 groups of 100 wafers each.

[0008] Step 3: The first group of 100 pieces are polished normally, dewaxed and finally cleaned, and then SP1 test is carried out to calculate the scratch rate.

[0009] Step 4: The second group first soaks the pipes and polishing heads in 48% KOH: water = 1:2 for 4 to 6 hours.

[0010] Step 5: The second group of 100 pieces are polished, dewaxed and finally cleaned, and then the SP1 test is carried out to measure the incidence of planned damage.

[0011] Step 6: Compare the scratch incidence of the two polished silicon wafers. The scratch incidence is reduced from 2% in the control group to 0.5%.

[0012] Preferably, during rough polishing and medium polishing, the ratio of the rough polishing liquid to the medium polishing liquid is 1:20; during fine polishing, the ratio of the fine polishing liquid is 1:15.

[0013] Preferably, the main components of the rough polishing liquid, silicon wafer intermediate polishing liquid and fine polishing liquid include solvent, additive and abrasive.

[0014] Preferably, during the rough polishing process, the rough polishing liquid flow rate is 8±2 L / min, the fixed plate speed is 35 rpm / min, the center speed is 77 rpm / min, and the processing time is 6 min.

[0015] Preferably, during the middle polishing process, the flow rate of the middle polishing liquid is 8±2 L / min, the fixed plate speed is 30 rpm / min, the center speed is 66 rpm / min, and the processing time is 6 min.

[0016] Preferably, during the fine polishing process, the fine polishing liquid flow rate is 2±0.2 L / min, the fixed plate speed is 20 rpm / min, the polishing head speed is 20 rpm / min, and the processing time is 6 min.

[0017] As a preference, the polishing line of FUJIKOSHUI was selected as the experimental machine.

[0018] The SP1 test preferably uses a fixed laser to illuminate a rotating wafer, using either normal or oblique incidence beams, and collects the scattered light of particles in dark field (DF) for particle size and count.

[0019] The present invention can achieve the following effects: The present invention provides a process for reducing scratches on the polishing surface, which has the advantages of convenient operation and good running stability compared with the prior art, and solves the problem that the surface of the silicon wafer is easily scratched during the polishing process. DETAILED DESCRIPTION

[0020] The technical solution of the invention is further specifically described below through embodiments.

[0021] Embodiment: A process for reducing scratches on a polished surface comprises the following steps: Step 1: Take a polishing line with crystals on the polishing head and pipe for experiment. Choose the polishing line of Fujikoshi as the experimental machine.

[0022] Step 2: Take 200 lightly doped borosilicate wafers and compare them before and after crystallization, and divide them into 2 groups of 100 wafers each.

[0023] Step 3: The first group of 100 pieces are polished normally, dewaxed and finally cleaned, and then SP1 test is carried out to calculate the scratch rate.

[0024] Step 4: The second group first soaks the pipes and polishing heads in 48% KOH: water = 1:2 for 4 to 6 hours.

[0025] Step 5: The second group of 100 pieces are polished, dewaxed and finally cleaned, and then SP1 test is performed to calculate the incidence of planned damage. The SP1 test uses a fixed laser to illuminate the rotating wafer, using a normal or oblique incident beam to collect the scattered light particle size and number of particles in the dark field.

[0026] When performing rough polishing and medium polishing, the ratio of the rough polishing liquid to the medium polishing liquid is 1:20; when performing fine polishing, the ratio of the fine polishing liquid is 1:15. The main components of the rough polishing liquid, the silicon wafer medium polishing liquid, and the fine polishing liquid include solvents, additives, and abrasives.

[0027] During the rough polishing process, the rough polishing liquid flow rate is 8±2L / min, the fixed plate speed is 35rpm / min, the center speed is 77rpm / min, and the processing time is 6min.

[0028] During the middle polishing process, the flow rate of the middle polishing liquid is 8±2L / min, the fixed plate speed is 30rpm / min, the center speed is 66rpm / min, and the processing time is 6min.

[0029] During the fine polishing process, the fine polishing liquid flow rate is 2±0.2L / min, the fixed plate speed is 20rpm / min, the polishing head speed is 20rpm / min, and the processing time is 6min.

[0030] Step 6: Compare the scratch incidence of the two polished silicon wafers. The scratch incidence is reduced from 2% in the control group to 0.5%.

[0031] In summary, the process for reducing scratches on the polished surface has the advantages of convenient operation and good running stability. It solves the problem of easy scratches on the surface during the polishing process of silicon wafers. The incidence of scratches on the surface of silicon wafers during polishing is reduced from 5% to 0.5%.

[0032] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A process for reducing scratches on a polished surface, characterized in that The steps are as follows: Step 1: Take a line with crystals on the polishing head and pipe for experiment; Step 2: Take 200 lightly doped boron silicon wafers and compare them before and after crystallization, and divide them into 2 groups of 100 wafers each; Step 3: The first group of 100 pieces are polished normally, dewaxed and finally cleaned, and then SP1 test is performed to calculate the scratch rate; Step 4: The second group first soaks the pipe and polishing head in 48% KOH: water = 1:2 for 4 to 6 hours; Step 5: The second group of 100 pieces are polished, dewaxed and finally cleaned, and then the SP1 test is carried out to calculate the incidence of planned damage; Step 6: Compare the scratch incidence rates of the two polished surfaces of the silicon wafer.

2. The process for reducing scratches on a polished surface according to claim 1, characterized in that: When performing rough polishing and medium polishing, the ratio of the rough polishing liquid to the medium polishing liquid is 1:20; when performing fine polishing, the ratio of the fine polishing liquid is 1:

15.

3. The process for reducing scratches on a polished surface according to claim 2, characterized in that: The main components of the rough polishing liquid, silicon wafer intermediate polishing liquid and fine polishing liquid include solvent, auxiliary agent and abrasive.

4. The process for reducing scratches on a polished surface according to claim 2, characterized in that: During the rough polishing process, the rough polishing liquid flow rate is 8±2L / min, the fixed plate speed is 35rpm / min, the center speed is 77rpm / min, and the processing time is 6min.

5. The process for reducing scratches on a polished surface according to claim 2, characterized in that: During the middle polishing process, the flow rate of the middle polishing liquid is 8±2L / min, the fixed plate speed is 30rpm / min, the center speed is 66rpm / min, and the processing time is 6min.

6. The process for reducing scratches on a polished surface according to claim 2, characterized in that: During the fine polishing process, the fine polishing liquid flow rate is 2±0.2L / min, the fixed plate speed is 20rpm / min, the polishing head speed is 20rpm / min, and the processing time is 6min.

7. The process for reducing scratches on a polished surface according to claim 1, characterized in that: The polishing line of Fujikoshi was selected as the experimental machine.

8. The process for reducing scratches on a polished surface according to claim 1, characterized in that: The SP1 test uses a fixed laser to illuminate a rotating wafer, using either normal or oblique incidence beams, and collects the scattered light of particles in a dark field to measure particle size and count.