A fine polishing liquid for improving polishing marks on silicon wafer surface and its application

Abstract

The invention relates to a fine polishing liquid for improving the polishing marks on the surface of a silicon wafer and an application thereof. The fine polishing liquid is prepared by mixing the following materials in 100% by weight: 2-12% of silica sol, 0.1-1% of an amide wetting and dispersing agent, 0.1-1.5% of a polymer alcohol lubricant, more than 0.3% of a pH regulator, and the pH value of the fine polishing liquid is 9-11 as a whole, and the balance is deionized water. The fine polishing liquid can effectively solve the problem of micro scratches on the surface of a silicon wafer after polishing, and can improve the polishing marks on the surface of the silicon wafer after fine polishing, presenting a state of slight polishing marks or no polishing marks, thereby meeting the precision requirements of the semiconductor industry.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing, and in particular to a fine polishing liquid for improving polishing marks on a silicon wafer surface and application thereof. Background Art

[0002] With the rapid development of the integrated circuit industry, its feature size continues to shrink, which puts higher requirements on the quality of the silicon substrate surface. Chemical mechanical polishing is a key process to achieve global and local flattening of silicon wafers. The selection of appropriate polishing liquid can achieve high-quality surface polishing. Silicon wafer polishing is divided into rough polishing and fine polishing. Fine polishing is the last step of silicon wafer polishing, which will affect the surface quality of the entire silicon wafer. After fine polishing, the silicon wafer surface is required to have no polishing marks, no polishing fog, low roughness, no metal ion pollution, hydrophilicity and less than 10 96nm particles. Among them, the metal ions and particles on the surface of the silicon wafer can be further resolved by cleaning, while the polishing marks must be resolved by optimizing the fine polishing liquid.

[0003] CN101092541A discloses a fine polishing liquid for silicon wafers, which uses silica sol with a small particle size of 10-60nm and Al2O3 or CeO2 hydrosol to compound, so that the wafer surface is not damaged after polishing. However, the hardness of Al2O3 hydrosol is greater than that of silica sol, and CeO2 hydrosol is prone to stratification, which cannot guarantee the stability of the polishing liquid and the surface quality of the silicon wafer after CMP.

[0004] CN111978868A discloses a method for preparing a silicon wafer chemical mechanical polishing liquid, which uses modified nano-silicon dioxide sol as an abrasive. The silicon dioxide particles modified with macromolecules can reduce the damage to the polishing surface during the polishing process. However, the Na + The high content and complicated preparation process are not conducive to the production control process of the fine polishing liquid. Loss of control of the production process will also cause the fine polishing liquid to fail and cause damage to the surface of the silicon wafer.

[0005] CN113881347A discloses a chemical mechanical polishing liquid for silicon wafers, which uses a compound of poly-ellipsoidal and single-spherical silicon dioxide as abrasive particles so that large particles increase the friction area during the grinding process and small particles act as a lubricant during the grinding process, thereby reducing scratches on the silicon wafer.

[0006] CN102061131B discloses a polishing liquid for reducing micro scratches on the surface of silicon wafers. The polishing liquid mainly reduces the scratch problem on the surface of silicon wafers by optimizing the filtration process to control the amount of LPC in the polishing liquid. The polishing liquid is suitable for the rough polishing process of silicon wafers. Summary of the invention

[0007] In order to solve the problem that polishing marks are easily generated on the surface of silicon wafers during the fine polishing process, a fine polishing liquid for improving the polishing marks on the surface of silicon wafers and its application are provided. The fine polishing liquid of the present invention can solve the problem of polishing marks in the fine polishing process of silicon wafers, and can improve the polishing marks on the surface of silicon wafers after fine polishing, presenting a state of slight polishing marks or no polishing marks.

[0008] In order to achieve the above objectives, the present invention is implemented by the following technical solutions:

[0009] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 2-12% silica sol, 0.1-1% amide wetting and dispersing agent, 0.1-1.5% polymer alcohol lubricant, more than 0.3% pH regulator and making the overall pH value of the fine polishing liquid 9-11, and the balance is deionized water.

[0010] Preferably, a fine polishing liquid for improving polishing marks on the surface of silicon wafers is mixed with the following materials in 100% by weight: 8-10% silica sol, 0.2-0.5% amide wetting and dispersing agent, 0.1-0.3% polymer alcohol lubricant, more than 0.3% pH adjuster and making the overall pH value of the fine polishing liquid 9-11, and the balance is deionized water.

[0011] More preferably, a fine polishing liquid for improving polishing marks on the surface of silicon wafers is mixed by the following materials in 100% by weight: 9.5% silica sol, 0.3% amide wetting and dispersing agent, 0.2% polymer alcohol lubricant, more than 0.3% pH adjuster and making the overall pH value of the fine polishing liquid 9-11, and the balance is deionized water.

[0012] Furthermore, the amide wetting and dispersing agent is povidone and / or cationic polyacrylamide; and the polymer alcohol lubricant is polyvinyl alcohol and polyethylene glycol in an equal mass ratio.

[0013] Further, the polyvinyl alcohol is one or more of PVA3-98, PVA5-98, PVA28-98, PVA60-98, PVA17-94, PVA27-96, PVA3-88, PVA5-88, PVA22-88, PVA30-88, PVA44-88, PVA95-88, PVA3-80, PVA32-80, PVA35-80, PVA48-80, and PVA5-74;

[0014] The polyethylene glycol is one or more of PEG200, PEG400, PEG600, PEG1500, PEG2000, PEG3350, PEG4000, PEG6000, PEG8000, PEG10000, and PEG20000; preferably, the polyethylene glycol is one or more of PEG400, PEG600, PEG1500, PEG2000, PEG3350, PEG4000, and PEG6000.

[0015] Further, the pH adjuster is one or more of ammonia water, tetramethylammonium hydroxide (TMAH), diethylenetriamine, triethylenetetramine, monoethanolamine, triethanolamine, citric acid monohydrate, and glycine; preferably, the pH adjuster is ammonia water and tetramethylammonium hydroxide (TMAH), and the mass ratio of ammonia water to tetramethylammonium hydroxide (TMAH) is 5:3.

[0016] Furthermore, the silica particles in the silica sol have a size of 30-100 nm.

[0017] The above polishing liquid for improving polishing marks on the surface of silicon wafers is used in the polishing stage of chemical mechanical polishing. The polishing liquid is diluted with deionized water and then polished on the silicon wafer. The dilution is carried out according to a mass ratio of the polishing liquid to the deionized water of 1:30-40.

[0018] Beneficial technical effects:

[0019] The present invention adopts cationic polyacrylamide and / or polyvidone containing amide groups and polyvinyl alcohol containing hydroxyl groups as wetting / lubricating dispersants. Due to the presence of quaternary ammonium salt in cationic polyacrylamide, the nitrogen atoms therein are positively charged, and the nitrogen atoms in the amide groups of polyvidone are positively charged. Under alkaline conditions, the cationic polyacrylamide and / or polyvidone can be adsorbed on the negatively charged surface of silica sol through electrostatic action. However, due to the three-dimensional structure of cationic polyacrylamide and / or polyvidone, the adsorption area on the surface of silica sol particles is large, and the adsorption film strength is weak. The hydroxyl groups in polyvinyl alcohol are adsorbed on the surface of silica sol covered with Si-OH hydration film through hydrogen bonds, and the adsorption area is small, and the adsorption film strength is large. The gaps between cationic polyacrylamide and / or polyvidone and silica sol particles can be filled, so that the coating layer on the surface of silica sol is more solid, thereby improving the steric hindrance effect and the dispersibility of silica sol, preventing the problem of polishing marks caused by agglomeration of silica sol and direct contact with silicon wafers, and thus solving the problem of serious polishing marks in the process of fine polishing of silicon wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The actual pictures are the surface of the silicon wafer after being polished with the polishing liquid of Example 1 (slight polishing marks) and the actual pictures of the surface of the silicon wafer after being polished with the polishing liquid of Comparative 4 (severe polishing marks). DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Unless otherwise specifically stated, the numerical value set forth in these embodiments does not limit the scope of the present invention. The technology and method known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology and method should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values.

[0023] The experimental methods in the following examples without specifying specific conditions are usually measured according to national standards; if there is no corresponding national standard, it is carried out according to the general international standards or the standard requirements proposed by relevant enterprises. Unless otherwise specified, all parts are by weight and all percentages are by weight.

[0024] Example 1

[0025] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average particle size of silicon dioxide is 70 nm, mass concentration of silica sol is 19 wt%), 0.3% of povidone (K value is 30), 0.1% of PEG400, 0.1% of PVA 3-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0026] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0027] Example 2

[0028] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of povidone (K value 30), 0.1% of PEG400, 0.1% of PVA 5-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0029] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0030] Example 3

[0031] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 28-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the remainder is deionized water.

[0032] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0033] Example 4

[0034] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average particle size of silicon dioxide is 70 nm, mass concentration of silica sol is 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 60-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0035] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0036] Example 5

[0037] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 17-94, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0038] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0039] Example 6

[0040] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 27-96, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0041] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0042] Example 7

[0043] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average particle size of silicon dioxide is 70 nm, mass concentration of silica sol is 19 wt%), 0.3% of povidone (K value is 30), 0.1% of PEG400, 0.1% of PVA 3-88, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0044] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0045] Example 8

[0046] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of povidone (K value 30), 0.1% of PEG400, 0.1% of PVA 5-88, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0047] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0048] Example 9

[0049] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 22-88, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the remainder is deionized water.

[0050] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0051] Example 10

[0052] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 30-88, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the remainder is deionized water.

[0053] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0054] Embodiment 11

[0055] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 44-88, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the remainder is deionized water.

[0056] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0057] Example 12

[0058] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 95-88, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0059] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0060] Example 13

[0061] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of povidone (K value 30), 0.1% of PEG400, 0.1% of PVA 3-80, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0062] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0063] Embodiment 14

[0064] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 32-80, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the remainder is deionized water.

[0065] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0066] Embodiment 15

[0067] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 35-80, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0068] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0069] Example 16

[0070] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 48-80, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the remainder is deionized water.

[0071] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0072] Embodiment 17

[0073] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average particle size of silicon dioxide is 70 nm, mass concentration of silica sol is 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 5-74, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0074] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0075] Embodiment 18

[0076] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG600, 0.1% of PVA 3-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the remainder is deionized water.

[0077] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0078] Embodiment 19

[0079] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG1500, 0.1% of PVA 3-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the remainder is deionized water.

[0080] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0081] Embodiment 20

[0082] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average particle size of silicon dioxide is 70 nm, mass concentration of silica sol is 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG2000, 0.1% of PVA 3-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0083] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0084] Embodiment 21

[0085] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG4000, 0.1% of PVA 3-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0086] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0087] Embodiment 22

[0088] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG6000, 0.1% of PVA 3-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the balance is deionized water.

[0089] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0090] Embodiment 23

[0091] A fine polishing liquid for improving polishing marks on the surface of a silicon wafer is prepared by mixing the following materials in 100% by weight: 9.5% of silica sol (average silica particle size 70 nm, mass concentration of silica sol 19 wt%), 0.3% of cationic polyacrylamide, 0.1% of PEG400, 0.1% of PVA 3-98, 0.5% of ammonia water, 0.3% of TMAH, the overall pH value of the fine polishing liquid is between 9 and 11, and the remainder is deionized water.

[0092] The above materials can be uniformly mixed according to the proportion to obtain the fine polishing liquid of this embodiment.

[0093] Comparative Example 1

[0094] The polishing liquid components of this comparative example are the same as those of Example 3, except that there is no povidone, PEG400, or PVA 28-98.

[0095] Comparative Example 2

[0096] The polishing liquid components of this comparative example are the same as those of Example 3, except that PEG400 and PVA 28-98 are not present.

[0097] Comparative Example 3

[0098] The polishing liquid components of this comparative example are the same as those of Example 3, except that there is no povidone.

[0099] Comparative Example 4

[0100] The polishing liquid components of this comparative example are the same as those of Example 3, except that PEG400 is not present.

[0101] Comparative Example 5

[0102] The polishing liquid composition of this comparative example is the same as that of Example 3, except that PVA 28-98 is not present.

[0103] The formulas of the above embodiments and comparative examples are shown in Table 1.

[0104] Table 1 Formulas of Examples and Comparative Examples

[0105]

[0106]

[0107]

[0108] Application Example 1

[0109] The polishing liquids of the above embodiments and comparative examples were used to perform fine polishing and cleaning of silicon wafers under the following conditions.

[0110] Polishing conditions: as shown in Table 2.

[0111] Table 2 Polishing conditions

[0112]

[0113] The total number of experiments in each case is 100 silicon wafers. The severity of polishing marks is determined by visual inspection under strong light. The defective ratio refers to the ratio of silicon wafers with severe polishing marks (defective wafers) to the total number of experimental wafers. The polishing results are shown in Table 3.

[0114] Table 3 Results of polishing in each case

[0115]

[0116]

[0117] Note: No polishing marks indicate that the surface of the silicon wafer is normal upon visual inspection; slight polishing marks indicate that there are a few minor scratches on the surface of the silicon wafer upon visual inspection; severe polishing marks indicate that there are many severe scratches on the surface of the silicon wafer upon visual inspection.

[0118] The actual picture of the silicon wafer surface (slight polishing marks) after polishing with the polishing liquid of Example 1 and the actual picture of the silicon wafer surface (severe polishing marks) after polishing with the polishing liquid of Comparative 4 are as follows: Figure 1 shown.

[0119] It can be seen from Table 1 and Table 3 that when no amide wetting and dispersing agent and / or alcohol lubricant is contained, the surface of the silicon wafer shows obvious severe polishing marks after fine polishing; only when both amide wetting and dispersing agent and alcohol lubricant are contained, there is no polishing mark or slight polishing mark. Among them, when the degree of polymerization of polyvinyl alcohol is low (degree of polymerization ≤ 500), there will be slight polishing marks. This is because the low degree of polymerization causes the high molecular alcohol lubricant to be insufficient to completely cover the surface of the silica sol particles, thereby causing slight polishing marks on the surface of the silicon wafer. When the degree of polymerization of PVA is increased, the polishing mark problem can be completely solved.

[0120] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fine polishing liquid for improving polishing marks on the surface of a silicon wafer, characterized in that: The polishing liquid is made of the following materials in 100% by weight: 8-10% silica sol, 0.3% amide wetting and dispersing agent, 0.2% polymer alcohol lubricant, more than 0.3% pH regulator and making the overall pH value of the polishing liquid 9-11, and the balance is deionized water; The average particle size of silicon dioxide in the silica sol is 70 nm; The amide wetting and dispersing agent is povidone K value 30 or cationic polyacrylamide; The polymer alcohol lubricant is polyvinyl alcohol and polyethylene glycol in equal mass ratio; The polyvinyl alcohol is one or more of PVA3-98, PVA5-98, PVA28-98, PVA60-98, PVA17-94, PVA27-96, PVA3-88, PVA5-88, PVA22-88, PVA30-88, PVA44-88, PVA95-88, PVA3-80, PVA32-80, PVA35-80, PVA48-80, and PVA5-74; The polyethylene glycol is one or more of PEG400, PEG600, PEG1500, PEG2000, PEG3350, PEG4000, and PEG6000.

2. The fine polishing liquid for improving the polishing marks on the surface of a silicon wafer according to claim 1, characterized in that: The pH regulator is one or more of ammonia water, tetramethylammonium hydroxide, diethylenetriamine, triethylenetetramine, monoethanolamine, triethanolamine, citric acid monohydrate, and glycine.

3. Use of a fine polishing liquid for improving polishing marks on a silicon wafer surface according to any one of claims 1 to 2 in the fine polishing stage of chemical mechanical polishing, characterized in that: The fine polishing liquid is diluted with deionized water and then fine polished on the silicon wafer, and the dilution is carried out according to a mass ratio of the fine polishing liquid to the deionized water of 1:30-40.

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