Silicon wafer rough polishing liquid

Abstract

The invention relates to the technical field of silicon wafer polishing, in particular to a silicon wafer rough polishing solution which comprises the following components in parts by weight: 20-50 parts of silica sol abrasive; 0.1 to 3 parts of a pH regulator; 0.01 to 1 part of a surfactant; the total part number is 100, and the balance is deionized water. The particle size of the grinding material in the silica sol grinding material is 20-150nm; the surfactant is selected from at least one of long-chain fatty alcohol-polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyoxyethylene fatty acid ester, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide and a polyether compound. According to the silicon wafer rough polishing liquid, unique advantages are given to the polishing liquid through the synergistic effect of the components, the polishing liquid can meet the rough polishing requirement, when the polishing liquid is applied to the rough polishing process, remarkable advantages are shown in the aspects of reducing the surface roughness, improving the surface quality and the like, the surface quality of a silicon wafer can be effectively improved, and wide application market prospects are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon wafer polishing, in particular to a silicon wafer rough polishing liquid. Background Art

[0002] Silicon wafers play an important role in modern technology, especially in the semiconductor and solar industries. Chemical mechanical polishing technology that reduces the roughness of silicon wafers is a key link in improving the surface quality of silicon wafers.

[0003] At present, chemical mechanical polishing technology mainly includes two key processes: rough polishing and fine polishing. Usually, the rough polishing process of silicon wafers tends to pursue how to improve the polishing rate. Therefore, traditional rough polishing liquids mostly use large-particle size and high-hardness abrasives to achieve higher polishing rates. However, traditional rough polishing liquids are prone to scratches, increased roughness and other defects on the surface of silicon wafers during the rough polishing process, affecting the surface quality of silicon wafers after subsequent fine polishing. Therefore, how to effectively improve the surface quality of silicon wafers, reduce surface roughness and improve the quality of polished products while ensuring the polishing rate is a technical problem that urgently needs to be solved. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a coarse polishing liquid which can significantly reduce the surface roughness of a silicon wafer.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A silicon wafer rough polishing liquid, comprising the following components in parts by weight:

[0007] 20-50 parts of silica sol abrasive;

[0008] pH regulator 0.1-3 parts;

[0009] Surfactant 0.01-1 part;

[0010] The total number of parts is 100, and the balance is deionized water;

[0011] The particle size of the abrasive in the silica sol abrasive is 20-150nm;

[0012] The surfactant is selected from at least one of long-chain fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides and polyether compounds.

[0013] Preferably, the surfactant is alkylphenol polyoxyethylene ether.

[0014] Preferably, the silica sol abrasive includes a first silica sol abrasive and a second silica sol abrasive; the particle size of the abrasive in the first silica sol abrasive is 20-60 nm; the particle size of the abrasive in the second silica sol abrasive is 90-150 nm.

[0015] Preferably, the mass ratio of the first silica sol abrasive to the second silica sol abrasive is (1-8):(1-3).

[0016] Preferably, the mass ratio of the first silica sol abrasive to the second silica sol abrasive is 7:3.

[0017] Preferably, the pH adjuster is selected from at least one of alkali metal hydroxides, alkali metal carbonates, quaternary ammonium hydroxides and amine compounds.

[0018] Preferably, the alkali metal hydroxide is selected from at least one of sodium hydroxide and potassium hydroxide.

[0019] Preferably, the alkali metal carbonate is selected from at least one of sodium carbonate and potassium carbonate.

[0020] The beneficial effects of the present invention are:

[0021] The silicon wafer rough polishing liquid provided in this application has core ingredients including sol-type silica, pH adjuster, high-quality surfactant and high-purity deionized water. The synergistic effect of these components gives the polishing liquid unique advantages, enabling it to meet the rough polishing needs. When used in the rough polishing process, it shows significant advantages in reducing surface roughness and improving surface quality. It can effectively improve the surface quality of silicon wafers and has broad application market prospects. DETAILED DESCRIPTION

[0022] The present invention is now further described in detail. The embodiments described below are exemplary and intended to be used to explain the present invention, but cannot be understood as limiting the present invention. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0023] In order to significantly reduce the surface roughness of a silicon wafer, the present application provides a silicon wafer rough polishing liquid, which comprises the following components in parts by weight:

[0024] 20-50 parts of silica sol abrasive;

[0025] pH regulator 0.1-3 parts;

[0026] Surfactant 0.01-1 part;

[0027] The total number of all components is 100 parts, and the balance is deionized water;

[0028] The particle size of the abrasive in the silica sol abrasive is 20-150nm; and the surfactant is preferably a non-ionic surfactant, and further preferably the surfactant is selected from at least one of long-chain fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide and polyether compounds.

[0029] Polishing liquid is usually composed of additives such as abrasives, surfactants, pH regulators, etc. The selection and ratio of various additives in the polishing liquid will seriously affect the surface quality of the silicon wafer, and the same additive may also play different roles in different polishing systems. Among them, the surfactant is a substance that can significantly reduce the surface tension of the target solution; the rough polishing liquid system provided in this application, according to the characteristics of the rough polishing process, is based on the fact that non-ionic surfactants exist in a molecular state in the solution, are not easily affected by the presence of strong electrolytes, are not easily affected by acids and alkalis, have high stability, and the molecules of non-ionic surfactants are uncharged, easy to get close, easy to form micelles and dense surface adsorption layers, and have high surface activity. The surface roughness of the silicon wafer is reduced by the synergistic effect of non-ionic surfactants, silica sol abrasives, and pH regulators. During the rough polishing process, macromolecular surfactants adhere to the surface of the silicon wafer to reduce the mechanical action of the abrasive and the chemical erosion of inorganic and organic bases, so as to achieve a high-quality surface with low roughness.

[0030] The silicon wafer rough polishing liquid provided in this application has core ingredients including sol-type silica, pH adjuster, high-quality surfactant and high-purity deionized water. The synergistic effect of these components gives the polishing liquid unique advantages, enabling it to meet the rough polishing needs. When used in the rough polishing process, it shows significant advantages in reducing surface roughness and improving surface quality. It can effectively improve the surface quality of silicon wafers and has broad application market prospects.

[0031] In order to further improve the surface quality of silicon wafers, the preferred surfactant in the present application is alkylphenol polyoxyethylene ether.

[0032] This application uses silica sol as an abrasive, utilizing the unique colloidal structure of sol-type silica and high concentration of silica colloidal particles. The nanoscale size of the colloidal particles enables them to easily penetrate into the microstructure of the workpiece surface, effectively increasing the removal rate of the silicon wafer.

[0033] In addition to removal rate and surface quality, with the continuous improvement of semiconductor equipment and performance, the requirements for the geometric accuracy of silicon wafers are getting higher and higher. At this time, traditional methods have been difficult to meet the strict requirements for the surface flatness and micro-geometric parameters of silicon wafers in modern microelectronics manufacturing. Therefore, in order to effectively improve the geometric parameters of the silicon wafer surface and ensure product quality while reducing surface roughness and improving polishing efficiency, the present application further prefers that the silica sol abrasive includes a first silica sol abrasive and a second silica sol abrasive; the particle size of the abrasive in the first silica sol abrasive is 20-60nm; the particle size of the abrasive in the second silica sol abrasive is 90-150nm.

[0034] Among them, small-particle silica sol has a faster removal rate, but it is easy to cause edge collapse, which has an adverse effect on geometric parameters; large-particle silica sol is easy to cause scratches and deteriorate geometric parameters. This application selects a combination of large and small particle sizes to ensure a higher removal rate while having a relatively reasonable filling efficiency and specific surface area. It is not easy to cause scratch damage and edge collapse effect, which helps to improve surface flatness and micro-geometric parameters.

[0035] Furthermore, in the present application, the geometric parameters are improved only by abrasive compounding, and the edge collapse phenomenon is avoided at the same time, and excessive chemical additives are not added. The principle of green chemistry is followed, and the discharge of chemical pollution waste is reduced.

[0036] The mixed composites of different abrasives have different effects on the geometric parameters of silicon wafers. The present application studies the effects of different mixed abrasives on the polishing liquid, thereby selecting a suitable ratio to significantly improve the surface geometric parameters of silicon wafers. Specifically, the present application prefers a mass ratio of the first silica sol abrasive to the second silica sol abrasive of (1-8): (1-3), and further prefers a mass ratio of the first silica sol abrasive to the second silica sol abrasive of 7:3.

[0037] The pH regulator of the present application is preferably selected from at least one of alkali metal hydroxides, alkali metal carbonates, quaternary ammonium hydroxides and amine compounds; and further preferably, the alkali metal hydroxide is selected from at least one of sodium hydroxide and potassium hydroxide; and the alkali metal carbonate is preferably selected from at least one of sodium carbonate and potassium carbonate.

[0038] The silicon wafer rough polishing liquid provided in the present application can keep the silicon wafer rough polishing liquid stable without adding too much additives, and make the surface roughness of the silicon wafer after polishing be within Within, it can well meet the production needs of industry.

[0039] In addition, the silicon wafer rough polishing liquid provided in the present application may also include a chelating agent according to needs; specifically, the chelating agent is preferably selected from at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentaethylenephosphonic acid and their derivatives.

[0040] The rough polishing liquid provided in this application plays an important role in improving the surface quality of silicon wafers and ensuring the geometric accuracy of silicon wafers. The TTV average value of the rough polishing liquid is <2.0, and the STIR average value is <0.62, which can meet the technical indicators of industrial production.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0042] Example 1

[0043] Polishing liquid ratio:

[0044] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 1 part of KOH; 0.02 parts of polyoxyethylene alkylamide; and the remainder is deionized water, with a total of 100 parts, to obtain No. 1 coarse polishing liquid, whose pH is about 10.8.

[0045] Polishing conditions:

[0046] Machine: Universal-300B; Pad: SUBA800; Polishing head / disc speed: 87 / 93rpm; Flow rate: 200ml / min; Polishing pressure: 2.00 / 0.00 / 2.13 / 2.15 / 4.00 / 5.25; Polishing plate temperature: 30±5℃, liquid dilution ratio is 1:20; Polishing time: 10min.

[0047] Example 2

[0048] Polishing liquid ratio:

[0049] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 1 part of KOH; 0.04 parts of polyoxyethylene alkylamide; and the remainder is deionized water, with a total of 100 parts, to obtain No. 2 coarse polishing liquid, whose pH is about 10.8.

[0050] Polishing conditions: same as in Example 1.

[0051] Example 3

[0052] Polishing liquid ratio:

[0053] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 1 part of KOH; 0.06 parts of polyoxyethylene alkylamide; and the remainder is deionized water, with a total of 100 parts, to obtain No. 3 coarse polishing liquid, whose pH is about 10.8.

[0054] Polishing conditions: same as in Example 1.

[0055] Example 4

[0056] Polishing liquid ratio:

[0057] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 1 part of KOH; 0.08 parts of polyoxyethylene alkylamide; and the remainder is deionized water, with a total of 100 parts, to obtain No. 4 coarse polishing liquid, whose pH is about 10.8.

[0058] Polishing conditions: same as in Example 1.

[0059] Example 5

[0060] Polishing liquid ratio:

[0061] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 1 part of KOH; 0.04 parts of fatty acid polyoxyethylene ester; and the remainder is deionized water, with a total of 100 parts, to obtain No. 5 coarse polishing liquid, whose pH is about 10.8.

[0062] Polishing conditions: same as in Example 1.

[0063] Example 6

[0064] Polishing liquid ratio:

[0065] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 1 part of KOH; 0.08 parts of fatty acid polyoxyethylene ester; and the remainder is deionized water, with a total of 100 parts, to obtain No. 6 coarse polishing liquid, whose pH is about 10.8.

[0066] Polishing conditions: same as in Example 1.

[0067] Example 7

[0068] Polishing liquid ratio:

[0069] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 1 part of KOH; 0.04 parts of alkylphenol polyoxyethylene ether; and the remainder is deionized water, with a total of 100 parts, to obtain No. 7 coarse polishing liquid, whose pH is about 10.8.

[0070] Polishing conditions: same as in Example 1.

[0071] Example 8

[0072] Polishing liquid ratio:

[0073] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 1 part of KOH; 0.08 parts of alkylphenol polyoxyethylene ether; and the remainder is deionized water, with a total of 100 parts, to obtain No. 8 coarse polishing liquid, whose pH is about 11.

[0074] Polishing conditions: same as in Example 1.

[0075] Example 9

[0076] Polishing liquid ratio:

[0077] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 0.5 parts of KOH; the remainder is deionized water, and the total number of parts is 100 parts, so as to obtain No. 9 rough polishing liquid, whose pH is about 10.8, which is the blank control group of the above embodiments 1-8.

[0078] Polishing conditions: same as in Example 1.

[0079] The surface roughness of the silicon wafers after polishing in the above-mentioned Examples 1-9 was tested, and the test results are shown in Table 1:

[0080] Table 1

[0081]

[0082] By comparing Examples 1-4, it can be seen that the roughness will be reduced by increasing polyoxyethylene alkylamide; by comparing Examples 5-6, it can be seen that the roughness will be reduced by increasing fatty acid polyoxyethylene ester; by comparing Examples 7-8, it can be seen that the roughness will be reduced by increasing alkylphenol polyoxyethylene ether; by comparing Examples 4, 6, 8, and 9, it can be seen that the effect of reducing the surface roughness is alkylphenol polyoxyethylene ether> fatty acid polyoxyethylene ester> polyoxyethylene alkylamide, and Example 8 has the best effect of reducing the surface roughness. Therefore, in order to improve the surface quality of silicon wafers on the production line, it is recommended to give priority to alkylphenol polyoxyethylene ether as a surfactant.

[0083] Example 10

[0084] Polishing liquid ratio:

[0085] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt%; 1 part of KOH; 0.05 parts of alkylphenol polyoxyethylene ether; and the remainder is deionized water, with a total of 100 parts, to obtain No. 10 coarse polishing liquid, whose pH is about 10.5.

[0086] Polishing conditions:

[0087] Machine: Universal-300B; Pad: SUBA800; Polishing head / disc speed: 87 / 93rpm; Flow rate: 200ml / min; Polishing pressure: 2.00 / 0.00 / 2.13 / 2.15 / 4.00 / 5.25; Polishing plate temperature: 30±5℃, liquid dilution ratio is 1:20; Polishing time: 20min.

[0088] Embodiment 11

[0089] Polishing liquid ratio:

[0090] Calculated by weight, it includes 30 parts of silica sol abrasive with a particle size of 120nm and a mass concentration of 40wt%; 1 part of KOH; 0.05 parts of alkylphenol polyoxyethylene ether; and the remainder is deionized water, with a total of 100 parts, to obtain No. 11 rough polishing liquid, whose pH is about 10.5.

[0091] Polishing conditions: same as Example 10.

[0092] Example 12

[0093] Polishing liquid ratio:

[0094] According to the weight proportion, it includes 30 parts of silica sol abrasive, which includes a first silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt% and a second silica sol abrasive with a particle size of 120nm and a mass concentration of 40wt%, and the mass ratio of the first silica sol abrasive to the second silica sol abrasive is 1:1; 1 part of KOH; 0.05 parts of alkylphenol polyoxyethylene ether; the remainder is deionized water, and the total number of parts is 100, so as to obtain No. 12 coarse polishing liquid, and its pH is about 10.5.

[0095] Polishing conditions: same as Example 10.

[0096] Embodiment 13

[0097] Polishing liquid ratio:

[0098] According to the weight proportion, it includes 30 parts of silica sol abrasive, which includes a first silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt% and a second silica sol abrasive with a particle size of 120nm and a mass concentration of 40wt%, and the mass ratio of the first silica sol abrasive to the second silica sol abrasive is 2:1; 1 part of KOH; 0.05 parts of alkylphenol polyoxyethylene ether; the remainder is deionized water, and the total number of parts is 100, so as to obtain No. 13 coarse polishing liquid, and its pH is about 10.5.

[0099] Polishing conditions: same as Example 10.

[0100] Embodiment 14

[0101] Polishing liquid ratio:

[0102] According to the weight proportion, it includes 30 parts of silica sol abrasive, which includes a first silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt% and a second silica sol abrasive with a particle size of 120nm and a mass concentration of 40wt%, and the mass ratio of the first silica sol abrasive to the second silica sol abrasive is 3:1; 1 part of KOH; 0.05 parts of alkylphenol polyoxyethylene ether; the remainder is deionized water, and the total number of parts is 100, so as to obtain No. 14 coarse polishing liquid, and its pH is about 10.5.

[0103] Polishing conditions: same as Example 10.

[0104] Embodiment 15

[0105] Polishing liquid ratio:

[0106] According to the weight proportion, it includes 30 parts of silica sol abrasive, which includes a first silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt% and a second silica sol abrasive with a particle size of 120nm and a mass concentration of 40wt%, and the mass ratio of the first silica sol abrasive to the second silica sol abrasive is 7:3; 1 part of KOH; 0.05 parts of alkylphenol polyoxyethylene ether; the remainder is deionized water, and the total number of parts is 100, so as to obtain No. 15 coarse polishing liquid, and its pH is about 10.5.

[0107] Polishing conditions: same as Example 10.

[0108] Example 16

[0109] Polishing liquid ratio:

[0110] According to the weight proportion, it includes 30 parts of silica sol abrasive, which includes a first silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt% and a second silica sol abrasive with a particle size of 120nm and a mass concentration of 40wt%, and the mass ratio of the first silica sol abrasive to the second silica sol abrasive is 8:2; 1 part of KOH; 0.05 parts of alkylphenol polyoxyethylene ether; the remainder is deionized water, and the total number of parts is 100, so as to obtain No. 16 coarse polishing liquid, and its pH is about 10.5.

[0111] Polishing conditions: same as Example 10.

[0112] Embodiment 17

[0113] Polishing liquid ratio:

[0114] According to the weight proportion, it includes 25 parts of silica sol abrasive, which includes a first silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt% and a second silica sol abrasive with a particle size of 120nm and a mass concentration of 40wt%, and the mass ratio of the first silica sol abrasive to the second silica sol abrasive is 7:3; 1 part of KOH; 0.05 parts of alkylphenol polyoxyethylene ether; the remainder is deionized water, and the total number of parts is 100, so as to obtain No. 17 coarse polishing liquid, and its pH is about 10.5.

[0115] Polishing conditions: same as Example 10.

[0116] Embodiment 18

[0117] Polishing liquid ratio:

[0118] According to the weight proportion, it includes 35 parts of silica sol abrasive, which includes a first silica sol abrasive with a particle size of 50nm and a mass concentration of 40wt% and a second silica sol abrasive with a particle size of 120nm and a mass concentration of 40wt%, and the mass ratio of the first silica sol abrasive to the second silica sol abrasive is 7:3; 1 part of KOH; 0.05 parts of alkylphenol polyoxyethylene ether; the remainder is deionized water, and the total number of parts is 100, so as to obtain No. 18 coarse polishing liquid, and its pH is about 10.5.

[0119] Polishing conditions: same as Example 10.

[0120] The flatness of the polished silicon wafer surface of Examples 10-18 was tested using an instrument for measuring geometric parameters. The geometric parameters of the polished silicon wafers of Examples 10-18 are shown in Table 2:

[0121] Table 2

[0122]

[0123] By comparing Examples 10-11, it can be seen that the geometric parameters of large-particle abrasives are slightly better, but the geometric parameters of single abrasives are worse than those of mixed abrasives; by comparing Examples 12-16, it can be seen that as the abrasive ratio gradually increases, the geometric parameters are increasingly optimized, reaching the optimum at 7:3; by comparing Examples 6, 8, and 9, it can be seen that increasing the solid content can also help improve the geometric parameters. In order to improve the geometric parameters and surface flatness of silicon wafers on the production line, it is recommended to give priority to the technical solution of Example 18.

[0124] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A silicon wafer rough polishing liquid, characterized in that: According to parts by weight, it includes the following components: 20-50 parts of silica sol abrasive; pH regulator 0.1-3 parts; Surfactant 0.01-1 part; The total number of parts is 100, and the balance is deionized water; The particle size of the abrasive in the silica sol abrasive is 20-150nm; The surfactant is selected from at least one of long-chain fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid polyoxyethylene esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides and polyether compounds.

2. The silicon wafer rough polishing liquid according to claim 1, characterized in that: The surfactant is alkylphenol polyoxyethylene ether.

3. The silicon wafer rough polishing liquid according to claim 1, characterized in that: The silica sol abrasive comprises a first silica sol abrasive and a second silica sol abrasive; the particle size of the abrasive in the first silica sol abrasive is 20-60 nm; the particle size of the abrasive in the second silica sol abrasive is 90-150 nm.

4. The silicon wafer rough polishing liquid as claimed in claim 3, characterized in that: The mass ratio of the first silica sol abrasive to the second silica sol abrasive is (1-8):(1-3).

5. The silicon wafer rough polishing liquid as claimed in claim 4, characterized in that: The mass ratio of the first silica sol abrasive to the second silica sol abrasive is 7:

3.

6. The silicon wafer rough polishing liquid according to claim 1, characterized in that: The pH adjuster is selected from at least one of alkali metal hydroxides, alkali metal carbonates, quaternary ammonium hydroxides and amine compounds.

7. The silicon wafer rough polishing liquid according to claim 6, characterized in that: The alkali metal hydroxide is selected from at least one of sodium hydroxide and potassium hydroxide.

8. The silicon wafer rough polishing liquid according to claim 6, characterized in that: The alkali metal carbonate is selected from at least one of sodium carbonate and potassium carbonate.

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