A mortar cutting fluid for semiconductor silicon wafers and its preparation method and application

Abstract

The present invention relates to a mortar cutting fluid for semiconductor silicon wafers and a preparation method and application thereof. The mortar cutting fluid comprises the following components calculated by weight: 10-40 parts of polyethylene glycol; 1-10 parts of an anti-settling agent; 1-5 parts of a chelating agent; 1-5 parts of a pH buffer pair; and 30-50 parts of ultrapure water. The cutting fluid of the present invention has excellent dispersion and anti-settling properties, and the cutting fluid of the present invention has a good pH buffering effect, and can maintain the pH between 6.5-7.5 during the cutting process. At the same time, it has an excellent anti-corrosion effect, and can avoid the problem of silicon powder agglomeration and corrosion disconnection during the mortar cutting process, and can also avoid the performance difference caused by pH mutation.

Description

Technical Field

[0001] The invention belongs to the technical field of cutting fluids, and in particular relates to a mortar cutting fluid for semiconductor silicon wafers, and a preparation method and application thereof. Background Art

[0002] In the process of cutting silicon ingots into silicon wafers, Si and C with high hardness (hardness between corundum and diamond), small particle size (6.5-24μm) and concentrated particle size distribution are used as the main cutting media. Si and C powders need to be evenly dispersed during the cutting process, and the huge friction heat generated during the cutting process also needs to be taken away in time. In this case, Si and C powders are generally added to the oil-soluble or water-soluble silicon wafer cutting fluid whose main raw material is polyethylene glycol in a certain proportion, and they also need to be prepared into a stable and uniform cutting mortar before silicon wafer cutting.

[0003] The principle of this technology is to use a high-speed moving steel wire to drive the cutting blade attached to it to rub the material to be cut. When the steel wire rubs the cutting material, the cutting fluid attached to the steel wire moves with the silicon carbide, and the cutting effect is achieved through the mutual friction between the three. Among them, the silicon carbide particles play a "rolling-fracture" role between the silicon rod and the steel wire, and are the core material for cutting. The cutting fluid has three functions: cutting, viscosity, and cooling, which can effectively improve the production efficiency and quality of silicon wafers.

[0004] The present invention improves the dispersibility of the cutting fluid so that the mortar in the cutting fluid is dispersed more evenly, thereby improving the contact between the mortar and the silicon ingot during the cutting process and improving the quality of the silicon wafer. Summary of the invention

[0005] The technical problem solved by the present invention is to improve the performance of the cutting fluid, thereby improving the contact between the mortar and the silicon ingot during the cutting process and improving the quality of the silicon wafer.

[0006] In view of the technical problems existing in the prior art, the present invention designs a mortar cutting fluid for semiconductor silicon wafers and its preparation method and application. The cutting fluid has excellent dispersion and anti-settling properties, and has a good pH buffering effect, which can maintain the pH between 6.5-7.5 during the cutting process. It also has an excellent anti-corrosion effect, which can avoid silicon powder agglomeration and corrosion disconnection problems during the mortar cutting process, and also avoid performance differences caused by pH mutations.

[0007] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising" and similar meanings, and closed-ended "consisting of..." and similar meanings.

[0008] In order to solve the above-mentioned technical problems, the present invention adopts the following solutions:

[0009] A mortar cutting fluid for semiconductor silicon wafers, characterized in that it comprises the following components calculated by weight:

[0010] 10-40 parts of polyethylene glycol;

[0011] 1-10 parts of anti-settling agent;

[0012] 1-5 parts of chelating agent;

[0013] pH buffer pair 1-5 parts;

[0014] 30-50 parts of ultrapure water;

[0015] The anti-settling agent is at least two of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride (CAS No.: 1310812-52-2, structural formula see the figure below), o-aminobenzamide, succinimide, formamide, and benzamide.

[0016]

[0017] Furthermore, the anti-settling agent is a mixture of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride and o-aminobenzamide.

[0018] Furthermore, the mass ratio of the (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride to o-aminobenzamide is (1-5):1.

[0019] Furthermore, the chelating agent is one or more of disodium ethylenediaminetetraacetic acid, nitrilotriacetic acid, and N-hydroxyethylethylenediaminetriacetic acid.

[0020] Furthermore, the pH buffer pair is a mixture of potassium dihydrogen phosphate and sodium hydroxide, or a mixture of sodium dihydrogen phosphate and disodium hydrogen phosphate, or a mixture of phthalic acid and potassium hydrogen phthalate.

[0021] Furthermore, the pH buffer pair is a mixture of potassium dihydrogen phosphate and sodium hydroxide.

[0022] Furthermore, the mass ratio of potassium dihydrogen phosphate to sodium hydroxide is 5:(2-3).

[0023] Furthermore, the mass ratio of potassium dihydrogen phosphate to sodium hydroxide is 5:2.

[0024] Furthermore, the pH of the cutting fluid of the present invention is 6.5-7.5.

[0025] Furthermore, the ultrapure water is deionized water with a resistance greater than or equal to 18 MΩ.

[0026] The present invention also provides a method for preparing a mortar cutting fluid for semiconductor silicon wafers, which is characterized by comprising the following steps:

[0027] Step 1: Weigh each component in its respective amount;

[0028] Step 2: Add all components except ultrapure water into the container and inject ultrapure water while stirring continuously.

[0029] The present invention also provides a use of a mortar cutting fluid for semiconductor silicon wafers in cutting semiconductor silicon wafers.

[0030] In the present invention, in order to further optimize the effect of the cutting fluid, the various components thereof can be preferably selected as follows: 20-30 parts of polyethylene glycol; 4-8 parts of anti-settling agent; 1-2 parts of chelating agent; 1-2 parts of pH buffer; and 35-45 parts of ultrapure water.

[0031] In the present invention, the mass ratio of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride to o-aminobenzamide is preferably (3-4):1, and the mass ratio of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride to o-aminobenzamide can also be most preferably 4:1.

[0032] In the present invention, the chelating agent is preferably disodium ethylenediaminetetraacetate.

[0033] The invention provides a mortar cutting fluid for silicon wafer cutting. The cutting fluid of the invention can be directly used in the silicon wafer cutting process without any special steps.

[0034] The inventors have found that o-aminobenzamide has an excellent anti-settling effect, and also has high strength, high temperature stability and corrosion resistance.

[0035] The inventors have found that the amino group and amide group at the ortho position of o-aminobenzamide will form an ortho effect, and there is a steric hindrance effect between the substituents in the ortho effect; the steric hindrance effect mainly refers to the spatial hindrance caused by the proximity of certain atoms or groups in the molecule. If the atoms are too close, two adjacent atoms will form overlapping electron clouds (manifested as repulsion), and this repulsive force makes it have excellent dispersion performance.

[0036] The inventors have found that o-aminobenzamide has charge repulsion, which makes it have excellent dispersibility and can work together with (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride. Due to the special functional group amino group of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride, it can form a network space structure with o-aminobenzamide, thereby achieving more excellent dispersibility and anti-sedimentation performance; in addition, due to its special five-membered ring structure, it has excellent stability, so that the formed network structure is extremely strong, thereby achieving excellent dispersibility.

[0037] The present invention provides a mortar cutting fluid for semiconductor silicon wafers and a preparation method and application thereof, which have the following beneficial effects:

[0038] 1. The anti-settling agent of the present invention is preferably a mixture of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride and o-aminobenzamide. The o-aminobenzamide has charge repulsion, which makes it have excellent dispersibility and can work together with (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride. Due to the special functional group amino group of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride, it can form a network space structure with o-aminobenzamide, thereby achieving more excellent dispersibility and anti-settling performance; in addition, due to its special five-membered ring structure, it has excellent stability, so that the formed network structure is extremely strong, thereby achieving excellent dispersibility.

[0039] 2. The buffer pair used in the present invention can maintain the pH of the cutting fluid at 6.5-7.5, thereby avoiding instability caused by large-scale pH fluctuations or the occurrence of acid corrosion and wire breakage problems.

[0040] 3. The chelating agent used in the present invention can chelate with the metal ions remaining in the water, thereby playing the role of anti-corrosion and synergism.

[0041] 4. The cutting fluid of the present invention has no special requirements for the silicon wafer cutting process, no special processing flow, and low volatile loss. After cutting, the silicon wafer only needs to be rinsed with pure water, which is harmless to the environment and human body. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 : A schematic diagram of the test results of particle size distribution of cutting fluids prepared using Comparative Example 1, Comparative Example 2, Comparative Example 3 and Example 1;

[0043] Figure 2: An optical microscope picture of a diamond wire magnified 900 times after cutting using the cutting fluid prepared in Example 1;

[0044] Figure 3 : An optical microscope picture of the diamond wire magnified 900 times after cutting using the cutting fluid prepared in Comparative Example 1. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with specific embodiments and accompanying drawings:

[0046] Table 1 Example 1-Example 8

[0047]

[0048] Table 2 Comparative Example 1-Comparative Example 3

[0049]

[0050] Table 3 Test results

[0051]

[0052] About the preparation method of the cutting fluid of the present invention:

[0053] The present invention involves multiple groups of cutting fluid preparation methods, all of which are completed by referring to the following steps:

[0054] Step 1: Weigh each component in its respective amount;

[0055] Step 2: Add all components except ultrapure water into the container and inject ultrapure water while stirring continuously.

[0056] About performance testing and description:

[0057] The cutting fluid and silicon carbide were mixed and stirred, wherein the silicon carbide was 300 mesh and the mass ratio of the cutting fluid to the silicon carbide was 95:5, and a performance test was performed.

[0058] The test method for performance 1 disconnection rate is:

[0059] The wire breakage rate refers to the ratio of the number of wire breaks during cutting on the same day to the total number of wire breaks during cutting on the same day.

[0060] The calculation formula is: number of broken knives / total number of knives*100%=broken wire rate.

[0061] Performance 2 The test method for pH change is:

[0062] The buffering properties of the cutting fluid were evaluated by the pH value fluctuation during the cutting process.

[0063] The test method for performance 3 particle size distribution is:

[0064] The test was carried out using a laser particle size analyzer.

[0065] Analysis of the test results:

[0066] It can be seen from the test results in Table 3 that in the embodiments of the present invention, the overall pH change is small and the wire breakage rate is low, which means that the cutting fluid of the present invention is more stable and has a better cutting effect.

[0067] In Comparative Example 1, the addition of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride in the anti-settling agent is missing, resulting in the cutting fluid lacking the dispersing effect generated by electrostatic repulsion, the dispersing performance of the cutting fluid deteriorates, the silicon powder agglomerates severely, and the agglomerated silicon powder particles adhere to the surface of the silicon ingot, increasing the diamond wire sticking and breaking rate. Therefore, the addition of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride can effectively improve the silicon powder agglomeration problem, thereby reducing the wire breakage rate.

[0068] In Comparative Example 2, the addition of o-aminobenzamide in the anti-settling agent is missing, resulting in the lack of synergistic effect with (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride, and the inability to form a network structure to achieve a better dispersion and anti-settling effect, which also leads to an increase in the line breakage rate; therefore, the addition of o-aminobenzamide can cooperate well with (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride, play an excellent anti-settling and dispersing role, and effectively reduce the line breakage rate.

[0069] In Comparative Example 3, the anti-settling agent of the present invention was not added, resulting in severe agglomeration of silicon powder during the cutting process, causing a high rate of wire jumper breakage. In summary, the introduction of two anti-settling agents for joint use can greatly reduce the wire breakage rate.

[0070] Further comparison is made through the attached drawings in the specification:

[0071] Figure 1 It is a schematic diagram of the test results of particle size distribution of cutting fluids prepared using Comparative Example 1, Comparative Example 2, Comparative Example 3 and Example 1;

[0072] like Figure 1 The results of the particle size distribution show:

[0073] Compared with Comparative Example 3, the particle size agglomeration of the single addition of o-aminobenzamide was improved, and the average particle size decreased from 26.69 μm to 23.76 μm.

[0074] The improvement was more obvious when (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride was added alone, and the average particle size decreased from 26.69 μm to 14.84 μm.

[0075] The synergistic use of the two improves the effect even more. The particle size of Example 1 can be reduced to 10.53 μm; the degree of particle agglomeration becomes smaller, indicating that the dispersibility and anti-settling properties of the cutting fluid are improved.

[0076] Figure 2 This is an optical microscope picture of a diamond wire magnified 900 times after cutting using the cutting fluid prepared in Example 1; Figure 3 This is an optical microscope picture of the diamond wire magnified 900 times after cutting using the cutting fluid prepared in Comparative Example 1.

[0077] from Figure 2 and Figure 3 It can be seen from the comparison that the cutting fluid prepared in Example 1 has better cutting effect and excellent anti-corrosion effect, and can effectively avoid the problem of corrosion and wire breakage during the mortar cutting process. However, after cutting with the cutting fluid prepared in Comparative Example 1, obvious corrosion and wire breakage occurred.

[0078] The cutting fluid of the present invention has excellent dispersion and anti-settling properties, and has good pH buffering effect, and can maintain the pH between 6.5-7.5 during the cutting process. It also has excellent anti-corrosion effect, and can avoid silicon powder agglomeration problems and corrosion and disconnection problems during the mortar cutting process, and can also avoid performance differences caused by pH mutations.

[0079] The present invention is described exemplarily above in conjunction with the embodiments and drawings. It is obvious that the implementation of the present invention is not limited to the above-mentioned methods. As long as various improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A mortar cutting fluid for semiconductor silicon wafers, characterized in that: Calculated by weight, it includes the following components: 10-40 parts of polyethylene glycol; 1-10 parts of anti-settling agent; 1-5 parts of chelating agent; pH buffer pair 1-5 parts; 30-50 parts of ultrapure water; The anti-settling agent is a mixture of (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride and o-aminobenzamide.

2. The mortar cutting fluid for semiconductor silicon wafers according to claim 1, characterized in that: The mass ratio of the (2S)-2-[(4-aminophenyl)methyl]hexahydro-1H-1,4,7-triazine-1,4,7-triacetic acid hydrochloride and o-aminobenzamide is (1-5):

1.

3. The mortar cutting fluid for semiconductor silicon wafers according to claim 1, characterized in that: The chelating agent is one or more of disodium ethylenediaminetetraacetic acid, nitrilotriacetic acid, and N-hydroxyethylethylenediaminetriacetic acid.

4. The mortar cutting fluid for semiconductor silicon wafers according to claim 1, characterized in that: The pH buffer pair is a mixture of potassium dihydrogen phosphate and sodium hydroxide or a mixture of sodium dihydrogen phosphate and disodium hydrogen phosphate or a mixture of phthalic acid and potassium hydrogen phthalate.

5. The mortar cutting fluid for semiconductor silicon wafers according to claim 4, characterized in that: The pH buffer pair is a mixture of potassium dihydrogen phosphate and sodium hydroxide, The mass ratio of potassium dihydrogen phosphate to sodium hydroxide is 5:(2-3).

6. The mortar cutting fluid for semiconductor silicon wafers according to claim 5, characterized in that: The mass ratio of potassium dihydrogen phosphate to sodium hydroxide is 5:

2.

7. A method for preparing a mortar cutting fluid for semiconductor silicon wafers according to any one of claims 1 to 6, characterized in that The following steps are involved: Step 1: Weigh each component in its respective amount; Step 2: Add all components except ultrapure water into the container and inject ultrapure water while stirring continuously.

8. Use of the mortar cutting fluid for semiconductor silicon wafers according to any one of claims 1 to 6 in cutting semiconductor silicon wafers.

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