Silicon wafer polishing process

Abstract

The invention provides a silicon wafer polishing process which comprises rough polishing, medium polishing and fine polishing, after fine polishing is completed, regional scrubbing is conducted in the radial direction of a polishing pad, and the scrubbing rate of the middle region of the polishing pad is larger than that of the outer side region and the inner side region of the polishing pad. The method has the beneficial effects that the polishing solution for primary fine polishing adopts the mixed solution of the polishing solution for medium polishing and the polishing solution for secondary fine polishing, the particle size of an abrasive in the polishing solution used in the primary fine polishing process is increased, and the removal amount of the primary fine polishing is increased, so that defects caused by rough polishing and medium polishing are repaired, and particles on the surface of a silicon wafer are effectively reduced. After polishing is completed, regional scrubbing is conducted in the radial direction of the polishing pad, the scrubbing rate of the middle region is larger than that of the outer side region and that of the inner side region, the outer side region and the inner side region with many polishing residues are fully scrubbed, the cleanliness of the polishing pad is improved, and the polishing effect of the polishing pad is guaranteed; and the flatness of the silicon wafer is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a silicon wafer polishing process. Background Art

[0002] Semiconductor silicon wafers are generally manufactured through processes such as single crystal growth, rolling, slicing, chamfering, grinding, etching, backside processing (polycrystalline, back sealing), edge removal, edge polishing, frontside polishing, cleaning, testing, and finally packaging. Frontside polishing uses chemical mechanical planarization (CMP), a process that uses simultaneous chemical and mechanical action to remove contamination and damage layers from the silicon wafer surface to obtain a mirror-like surface. Chemical mechanical planarization technology uses polishing pads to mechanically polish the surface of silicon wafers. It is usually divided into three steps: rough polishing, medium polishing, and fine polishing. After fine polishing, silicon wafers are usually required to have extremely low surface defects such as surface metal, surface particles, and scratches. Many factors affect the surface particles of polished wafers, such as the polishing process temperature, polishing pressure, and rotation speed. Therefore, the use of different process methods has a significant impact on the surface particles of silicon polished wafers. Fine polishing liquid often has a small particle size and a low removal volume, which cannot completely repair defects caused by rough polishing and medium polishing. In addition, with the reduction of semiconductor feature size and the increase of integration, the requirements for the flatness of the silicon wafer surface are becoming higher and higher. The original polishing process cannot meet the higher flatness requirements. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a silicon wafer polishing process, which effectively solves the technical problems that fine polishing cannot completely repair the defects caused by rough polishing and medium polishing during the silicon wafer polishing process, there are many particles on the silicon wafer surface, and the flatness of the silicon wafer cannot be guaranteed.

[0004] The technical solution adopted by the present invention is: a silicon wafer polishing process, including rough polishing, medium polishing and fine polishing. After completing the fine polishing, the polishing pad is scrubbed in different areas along the radial direction, and the scrubbing rate of the middle area of the polishing pad is greater than the scrubbing rate of the outer area and the inner area of the polishing pad.

[0005] Furthermore, the scrubbing rate of the middle area of the polishing pad is set to 0.4-1.2 rpm, and the scrubbing rates of the outer area and the inner area of the polishing pad are set to 0.3-0.5 rpm.

[0006] Furthermore, the fine polishing includes a primary fine polishing and a secondary fine polishing, and the abrasive particle size of the polishing liquid used in the primary fine polishing process is larger than the abrasive particle size of the polishing liquid used in the secondary fine polishing process.

[0007] Furthermore, the polishing liquid used in the rough polishing process is the first polishing liquid, the polishing liquid used in the intermediate polishing process is the second polishing liquid, the polishing liquid used in the first fine polishing process is the third polishing liquid, the polishing liquid used in the second fine polishing process is the fourth polishing liquid, and the third polishing liquid is a mixture of the second polishing liquid and the fourth polishing liquid.

[0008] Furthermore, during the coarse grinding process, the pressure per unit area is set to 150-430 g / cm 3 The abrasive of the first polishing liquid is silicon dioxide particles with a particle size of 70 to 80 nm, and the flow rate of the first polishing liquid is set to 8 to 16 L / min.

[0009] Furthermore, during the middle polishing process, the pressure per unit area is set to 100-250 g / cm 3 The abrasive of the second polishing liquid is silicon dioxide particles with a particle size of 40 to 50 nm, and the flow rate of the second polishing liquid is set to 4 to 8 L / min.

[0010] Furthermore, during the secondary polishing process, the pressure per unit area is set to 100-160 g / cm 3 The abrasive of the fourth polishing liquid is silicon dioxide particles with a particle size of 32 to 38 nm, and the flow rate of the fourth polishing liquid is set to 1.5 to 2.5 L / min.

[0011] Furthermore, during the fine polishing process, the pressure per unit area is set to 100-250 g / cm 3 In the third polishing liquid, the volume ratio of the second polishing liquid to the fourth polishing liquid is set to 1:2-4, and the flow rate of the third polishing liquid is set to 2-6 L / min.

[0012] Furthermore, during the scrubbing of the polishing pad, the rotation speed of the large disk is set to 25-50 rpm.

[0013] Furthermore, during the polishing process, the rotation speed of the large disk is set to 15 to 35 rpm.

[0014] The advantages and positive effects of the present invention are as follows: Due to the adoption of the above-mentioned technical solution, the polishing liquid for the first fine polishing process uses a mixture of the polishing liquids for the second fine polishing process, which increases the particle size of the abrasive in the polishing liquid used in the first fine polishing process and improves the amount of abrasive removed during the first fine polishing process, thereby repairing defects caused by the rough polishing and the second fine polishing process and effectively reducing particles on the silicon wafer surface. After polishing is completed, the polishing pad is scrubbed radially along different areas, with the scrubbing rate of the central area being greater than that of the outer and inner areas. The outer and inner areas with more polishing residues are thoroughly scrubbed, thereby improving the cleanliness of the polishing pad, ensuring the polishing effect of the polishing pad, and further improving the flatness of the silicon wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other objects, features, and advantages of the present invention will become more apparent through a more detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. The accompanying drawings are provided to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and are not intended to limit the present invention. In the drawings, the same reference numerals generally represent the same components or steps.

[0016] Figure 1 The present invention is a flow chart of a silicon wafer polishing process according to an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of a silicon wafer polishing process and a polishing pad scrubbing process according to an embodiment of the present invention.

[0018] Figure 3 This is a box plot of particles on the surface of a silicon wafer in a silicon wafer polishing process according to an embodiment of the present invention.

[0019] Figure 4 This is a STIR box plot of silicon wafer flatness in a silicon wafer polishing process according to an embodiment of the present invention.

[0020] Figure 5 This is a TTV box plot of silicon wafer flatness in a silicon wafer polishing process according to an embodiment of the present invention.

[0021] Figure 6 This is a grid diagram of silicon wafer flatness in a silicon wafer polishing process according to an embodiment of the present invention.

[0022] Figure 7 This is a box plot of particles on the surface of a silicon wafer in a silicon wafer polishing process according to another embodiment of the present invention.

[0023] Figure 8 This is a STIR box plot of silicon wafer flatness in a silicon wafer polishing process according to another embodiment of the present invention.

[0024] Figure 9 This is a TTV box diagram of silicon wafer flatness in a silicon wafer polishing process according to another embodiment of the present invention.

[0025] Figure 10 This is a grid diagram of silicon wafer flatness in a silicon wafer polishing process according to another embodiment of the present invention.

[0026] In the picture:

[0027] 1. Polishing pad 2. Brush arm 3. Rotating shaft

[0028] 4. Outer area 5. Middle area 6. Inner area DETAILED DESCRIPTION

[0029] An embodiment of the present invention provides a silicon wafer polishing process, which will be described below with reference to the accompanying drawings.

[0030] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "setting" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be a communication between the internal parts of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood based on specific circumstances.

[0031] like Figure 1 As shown, a silicon wafer polishing process according to an embodiment of the present invention includes rough polishing, medium polishing and fine polishing. After each car of silicon wafer polishing is completed, there will be residue on the surface of the polishing pad 1. In order to ensure the cleanliness and polishing effect of the polishing pad 1, a high-pressure water jet is used to brush the polishing pad 1 in different areas, such as Figure 2 As shown in the figure, a high-pressure water jet is connected to a scrubbing arm 2. Driven by a rotating shaft 3, the scrubbing arm 2 rotates above the polishing pad 1, moving the high-pressure water jet radially from the outer edge to the inner edge of the polishing pad 1. When the high-pressure water jet reaches the inner edge of the polishing pad 1, the rotating shaft 3 drives the scrubbing arm 2 to reverse its rotation, moving the high-pressure water jet radially from the inner edge to the outer edge of the polishing pad 1. The polishing pad 1 is radially divided from the outer side to the inner side into an outer region 4, a middle region 5, and an inner region 6. Due to the higher linear velocity on the outer side of the polishing pad 1, the outer region 4 leaves more residue after polishing than the middle region 5, while the inner region 6 is prone to residue accumulation. Therefore, the scrubbing rate of the middle region 5 is greater than that of the outer and inner regions 4 and 6. In other words, the outer and inner regions 4 and 6 use a slower scrubbing rate. The scrubbing rate is represented by the rotation rate of the scrubbing arm 2. A slower rotation rate of the scrubbing arm 2 allows for more thorough scrubbing of the outer and inner regions 4 and 6. The size division of the outer region 4 , the middle region 5 and the inner region 6 is not limited here.

[0032] Specifically, the scrubbing rate of the central region 5 of the polishing pad 1 is set to 0.4-1.2 rpm, and the scrubbing rate of the outer region 4 and the inner region 6 of the polishing pad 1 is set to 0.3-0.5 rpm. Preferably, the scrubbing rates of the outer region 4 and the inner region 6 of the polishing pad 1 are the same.

[0033] Specifically, during the process of scrubbing the polishing pad 1 in different areas, the rotation speed of the large disk is set to 25-50 rpm.

[0034] Specifically, the rough polishing includes the first rough polishing and the second rough polishing. The rough polishing pressure per unit area is set to 150-430 g / cm 3 The polishing liquid used in the rough polishing process is the first polishing liquid. The abrasive in the first polishing liquid is silica particles with a particle size of 70-80 nm. The volume ratio of the silica colloidal finished polishing liquid to deionized water in the first polishing liquid is 1:10-40. The flow rate of the first polishing liquid is set to 8-16 L / min.

[0035] Specifically, the pressure per unit area of the medium polishing is set to 100-250g / cm 3 The polishing liquid used in the intermediate polishing process is the second polishing liquid. The abrasive in the second polishing liquid is silica particles with a particle size of 40-50 nm. The volume ratio of silica colloidal finished polishing liquid to deionized water in the second polishing liquid is 1:25-50. The flow rate of the second polishing liquid is set at 4-8 L / min.

[0036] Specifically, fine polishing includes primary and secondary polishing. The abrasive particle size of the polishing slurry used in the primary polishing process is larger than that used in the secondary polishing process. Traditional fine polishing slurries have smaller abrasive particle sizes, resulting in a low removal rate during fine polishing and an inability to completely repair defects caused by rough and intermediate polishing. Consequently, the silicon wafer's particle size and surface condition are unsatisfactory for subsequent use. Increasing the abrasive particle size in the polishing slurry used in the primary polishing process increases the removal rate during the primary polishing process, thereby repairing defects caused by rough and intermediate polishing.

[0037] Specifically, during the secondary polishing process, the pressure per unit area is set to 100-160 g / cm 3 The polishing liquid used in the secondary fine polishing process is the fourth polishing liquid. The abrasive in the fourth polishing liquid is silicon dioxide particles with a particle size of 32-38 nm. The volume ratio of the silicon dioxide colloidal finished polishing liquid to deionized water in the fourth polishing liquid is 1:30-60. The flow rate of the fourth polishing liquid is set at 1.5-2.5 L / min.

[0038] Specifically, during a fine polishing process, the pressure per unit area is set to 100-250 g / cm 3 The polishing liquid used in the first fine polishing process is the third polishing liquid, which is a mixture of the second polishing liquid and the fourth polishing liquid. The volume ratio of the second polishing liquid to the fourth polishing liquid is set to 1:2-4. The volume ratio of the finished silica colloidal polishing liquid contained in the third polishing liquid to deionized water is 1:30-50. The flow rate of the third polishing liquid is set to 2-6 L / min.

[0039] Specifically, during the polishing process, the disk speed is set at 15-35 rpm, the polishing removal amount is 9-11 μm thinning, the polishing rate is controlled at 0.4-0.8 μm / min, the ice machine temperature is set at 15-25°C, and the polishing liquid temperature is set at 20±5°C.

[0040] Specifically, during the scrubbing of the polishing pad 1 , the rotation speed of the large disk is set to 25-50 rpm.

[0041] Example 1: A silicon wafer polishing process, wherein a wafer to be polished with a diameter of 200 mm is selected, and the silicon wafers are sorted into grades according to a thickness difference of 1 μm using an automatic sorter. After sorting, the wafers are loaded into a special loading basket of a polishing machine, and the wafer mounting operation is performed with the polished surface facing the H surface of the wafer basket. Polishing wax is used during the mounting process, and the wax dripping amount for a single wafer is 1.6±0.1 ml / wax. The mounting equipment is an automatic wafer mounting machine, and the mounted silicon wafers are stored on a ceramic tray loader, waiting for polishing.

[0042] S1, primary rough polishing and secondary rough polishing

[0043] The rough polishing pressure per unit area is set to 430g / cm 3 The polishing liquid used during the rough polishing process was the first polishing liquid. The abrasive in the first polishing liquid consisted of 70 nm silica particles. The volume ratio of silica colloidal finished polishing liquid to deionized water was 1:20. The flow rate of the first polishing liquid was set to 8 L / min. The disk speed was set to 25 rpm.

[0044] S3, medium throw

[0045] The pressure per unit area of the medium polishing is set to 150g / cm 3 The polishing liquid used in the intermediate polishing process was the second polishing liquid. The abrasive in the second polishing liquid consisted of 40nm silica particles. The volume ratio of silica colloidal finished polishing liquid to deionized water was 1:40. The flow rate of the second polishing liquid was set to 4L / min. The disk speed was set to 25rpm.

[0046] S4, first polishing and second polishing

[0047] During the secondary polishing process, the pressure per unit area is set to 120g / cm 3 The polishing liquid used in the secondary fine polishing process was the fourth polishing liquid. The abrasive in the fourth polishing liquid consisted of 32nm silica particles. The volume ratio of silica colloidal finished polishing liquid to deionized water was 1:60. The flow rate of the fourth polishing liquid was set to 1.5L / min. The platter speed was set to 25rpm.

[0048] During a fine polishing process, the pressure per unit area is set to 120g / cm 3The polishing liquid used in the first fine polishing process was the third polishing liquid, which was a mixture of the second and fourth polishing liquids. The volume ratio of the second polishing liquid, the fourth polishing liquid, and deionized water was set to 0.25:0.75:40, and the flow rate of the third polishing liquid was set to 2 L / min. The disk speed was set to 25 rpm.

[0049] S5. Cleaning silicon wafers

[0050] S51: After polishing is completed, the polishing wafer is peeled off from the ceramic plate by the automatic wafer unloader, placed in a special wafer unloading basket, and placed in the polishing transfer water cart; the polished silicon wafer is placed in 18 megohm pure water and waits for cleaning, isolating it from the air to prevent tiny particles and metals in the environment from contaminating the silicon wafer.

[0051] S52: Polished wafers are loaded into the pre-cleaning equipment in baskets to clean the polishing wax left on the back of the wafer during placement. The pre-cleaning process requires passing through a dewaxing tank, a liquid tank, and a slow pull tank. The dewaxing tank contains a dewaxing agent at a temperature of 30±5°C, and the liquid tank contains a mixture of NH4OH and H2O2 at a temperature of 70±5°C.

[0052] S6. Clean the polishing pad 1 in different areas

[0053] Driven by the rotating shaft 3, the scrubbing arm 2 rotates above the polishing pad 1, driving the high-pressure water jet to scrub the polishing pad 1 radially from the outer edge to the inner edge. The polishing pad 1 is divided radially from the outer side to the inner side into an outer region 4, a middle region 5, and an inner region 6. The scrubbing rate is set at 0.3 rpm for the outer region 4 and the inner region 6, and 0.6 rpm for the middle region 5. During the scrubbing of the polishing pad 1, the disc rotates at 25 rpm.

[0054] The surface particle size of the polished silicon wafer is tested, such as Figure 3 As shown, there are less than 5 particles with a diameter of 65 nm.

[0055] The surface flatness of the polished silicon wafer is tested, such as Figure 4 、 Figure 5 and Figure 6 As shown, the average STIR value is 0.18 μm and the average TTV value is 0.51 μm.

[0056] Example 2: A silicon wafer polishing process, wherein a wafer to be polished with a diameter of 200 mm is selected, and the silicon wafers are sorted into grades according to a thickness difference of 1 μm using an automatic sorter. After sorting, the wafers are loaded into a special loading basket for the polishing machine, and the wafer mounting operation is performed with the polished surface facing the H surface of the wafer basket. Polishing wax is used during the mounting process, and the wax dripping amount for a single wafer is 1.6±0.1 ml / wax. The mounting equipment is an automatic wafer mounting machine, and the mounted silicon wafers are stored on a ceramic tray loader, waiting for polishing.

[0057] S1, primary rough polishing and secondary rough polishing

[0058] The rough polishing pressure per unit area is set to 430g / cm 3 The polishing liquid used during the rough polishing process was the first polishing liquid. The abrasive in the first polishing liquid consisted of 80 nm silica particles. The volume ratio of silica colloidal finished polishing liquid to deionized water was 1:20. The flow rate of the first polishing liquid was set to 16 L / min. The platter speed was set to 25 rpm.

[0059] S3, medium throw

[0060] The pressure per unit area of the medium polishing is set to 150g / cm 3 The polishing liquid used in the intermediate polishing process was the second polishing liquid. The abrasive in the second polishing liquid consisted of 50nm silica particles. The volume ratio of silica colloidal finished polishing liquid to deionized water was 1:40. The flow rate of the second polishing liquid was set to 8L / min. The platter speed was set to 25rpm.

[0061] S4, first polishing and second polishing

[0062] During the secondary polishing process, the pressure per unit area is set to 120g / cm 3 The polishing liquid used in the secondary fine polishing process was the fourth polishing liquid. The abrasive in the fourth polishing liquid consisted of 38nm silica particles. The volume ratio of silica colloidal finished polishing liquid to deionized water was 1:60. The flow rate of the fourth polishing liquid was set to 2.5L / min. The platter speed was set to 25rpm.

[0063] During a fine polishing process, the pressure per unit area is set to 120g / cm 3 The polishing liquid used in the first fine polishing process was the third polishing liquid, which was a mixture of the second and fourth polishing liquids. The volume ratio of the second polishing liquid, the fourth polishing liquid, and deionized water was set to 0.2:0.8:40, and the flow rate of the third polishing liquid was set to 6 L / min. The disk speed was set to 25 rpm.

[0064] S5. Cleaning silicon wafers

[0065] S51: After polishing is completed, the polishing wafer is peeled off from the ceramic plate by the automatic wafer unloader, placed in a special wafer unloading basket, and placed in the polishing transfer water cart; the polished silicon wafer is placed in 18 megohm pure water and waits for cleaning, isolating it from the air to prevent tiny particles and metals in the environment from contaminating the silicon wafer.

[0066] S52: Polished wafers are loaded into the pre-cleaning equipment in baskets to clean the polishing wax left on the back of the wafer during placement. The pre-cleaning process requires passing through a dewaxing tank, a liquid tank, and a slow pull tank. The dewaxing tank contains a dewaxing agent at a temperature of 30±5°C, and the liquid tank contains a mixture of NH4OH and H2O2 at a temperature of 70±5°C.

[0067] S6. Clean the polishing pad 1 in different areas

[0068] Driven by the rotating shaft 3, the scrubbing arm 2 rotates above the polishing pad 1, driving the high-pressure water jet to scrub the polishing pad 1 radially from the outer edge to the inner edge. The polishing pad 1 is divided radially from the outer side to the inner side into an outer region 4, a middle region 5, and an inner region 6. The scrubbing rate for the outer region 4 and the inner region 6 is set to 0.5 rpm, while the scrubbing rate for the middle region 5 is set to 1.2 rpm. During the scrubbing of the polishing pad 1, the disc rotation speed is set to 25 rpm.

[0069] The surface particle size of the polished silicon wafer is tested, such as Figure 7 As shown, there are less than 7 particles with a diameter of 65 nm.

[0070] The surface flatness of the polished silicon wafer is tested, such as Figure 8 、 Figure 9 and Figure 10 As shown, the average STIR value is 0.25 μm and the average TTV value is 0.65 μm.

[0071] The advantages and positive effects of the present invention are:

[0072] 1. The polishing liquid for the first fine polishing is a mixture of the polishing liquids for the medium polishing and the second fine polishing. The particle size of the abrasive in the polishing liquid used in the first fine polishing process is increased, and the removal amount of the first fine polishing is increased, thereby repairing the defects caused by the rough polishing and the medium polishing, and effectively reducing the particles on the surface of the silicon wafer.

[0073] 2. After polishing is completed, the polishing pad is scrubbed in different areas along its radial direction. The scrubbing rate of the middle area is greater than that of the outer and inner areas. The outer and inner areas with more polishing residues are fully scrubbed, which improves the cleanliness of the polishing pad and ensures the polishing effect of the polishing pad, thereby further improving the flatness of the silicon wafer.

[0074] The embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that any implementations not depicted or described in the drawings or the main text of the specification are known to those skilled in the art and are not described in detail. Furthermore, the definitions of the various components described above are not limited to the specific structures, shapes, or methods described in the embodiments; those skilled in the art may easily modify or replace them.

[0075] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A silicon wafer polishing process, including rough polishing, medium polishing and fine polishing, characterized in that: After the fine polishing is completed, brushing is performed in different areas along the radial direction of the polishing pad, and the brushing rate of the middle area of the polishing pad is greater than the brushing rates of the outer area and the inner area of the polishing pad.

2. A silicon wafer polishing process according to claim 2, characterized in that: The scrubbing rate of the middle area of the polishing pad is set to 0.4-1.2 rpm, and the scrubbing rates of the outer area and the inner area of the polishing pad are set to 0.3-0.5 rpm.

3. A silicon wafer polishing process according to claim 1 or 2, characterized in that: The fine polishing includes primary fine polishing and secondary fine polishing, and the abrasive particle size of the polishing liquid used in the primary fine polishing process is larger than the abrasive particle size of the polishing liquid used in the secondary fine polishing process.

4. A silicon wafer polishing process according to claim 3, characterized in that: The polishing liquid used in the rough polishing process is the first polishing liquid, the polishing liquid used in the intermediate polishing process is the second polishing liquid, the polishing liquid used in the first fine polishing process is the third polishing liquid, and the polishing liquid used in the second fine polishing process is the fourth polishing liquid. The third polishing liquid is a mixture of the second polishing liquid and the fourth polishing liquid.

5. A silicon wafer polishing process according to claim 4, characterized in that: During the coarse grinding process, the pressure per unit area is set to 150-430 g / cm 3 The abrasive of the first polishing liquid is silicon dioxide particles with a particle size of 70 to 80 nm, and the flow rate of the first polishing liquid is set to 8 to 16 L / min.

6. A silicon wafer polishing process according to claim 5, characterized in that: During the middle polishing process, the pressure per unit area is set to 100-250 g / cm 3 The abrasive of the second polishing liquid is silicon dioxide particles with a particle size of 40 to 50 nm, and the flow rate of the second polishing liquid is set to 4 to 8 L / min.

7. A silicon wafer polishing process according to claim 6, characterized in that: During the secondary polishing process, the pressure per unit area is set to 100-160 g / cm 3 The abrasive of the fourth polishing liquid is silicon dioxide particles with a particle size of 32 to 38 nm, and the flow rate of the fourth polishing liquid is set to 1.5 to 2.5 L / min.

8. A silicon wafer polishing process according to claim 7, characterized in that: During the first fine polishing process, the pressure per unit area is set to 100-250 g / cm 3 In the third polishing liquid, the volume ratio of the second polishing liquid to the fourth polishing liquid is set to 1:2-4, and the flow rate of the third polishing liquid is set to 2-6 L / min.

9. A silicon wafer polishing process according to any one of claims 1-2 and 4-8, characterized in that: During the scrubbing of the polishing pad, the rotation speed of the large disk is set to 25-50 rpm.

10. A silicon wafer polishing process according to claim 9, characterized in that: During the polishing process, the rotation speed of the large disk is set to 15-35 rpm.

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