A kind of diamond wire fine line cutting monocrystalline large size thin silicon wafer cutting fluid

Abstract

The present application relates to a kind of diamond wire thin wire cutting monocrystalline large size thin silicon wafer cutting fluid, the diamond wire cutting fluid includes the following components: molecular weight wide distribution dispersant 20%~30%, wetting penetrant 15%~22%, lubricating dispersant 8%~15%, deionized water is the balance.This product has excellent dispersing performance and wetting performance, in the process of thin wire diameter diamond wire cutting large size silicon wafer, can play excellent dispersion effect, wetting band liquid performance, steel wire surface silicon powder chip removal capacity, wetting penetrant and wetting dispersant in high carbon number naphthenic alcohol head can form lubricating film layer on the surface of silicon wafer, reduce the adhesion between silicon wafer after cutting piece, reduce the lifting rod resistance, avoid lifting rod card line and silicon wafer surface scratch, while the dispersant of molecular weight wide distribution can provide more persistent fast silicon powder dispersion rate and efficiency.

Description

Technical Field

[0001] This invention relates to a cutting fluid for diamond wire cutting, and more particularly to a cutting fluid for cutting large-size thin single-crystal silicon wafers using fine diamond wire. Background Technology

[0002] Since the beginning of the 21st century, the production cost of renewable energy power generation, represented by solar and wind power, has continued to decrease. In the future, it will be highly competitive with fossil fuels, creating the necessary conditions for the formation of a new power system with renewable energy as its core. Photovoltaic power generation is one of the important means to support zero carbon. In the future, 90% of the world's energy will be renewable energy, of which more than 70% will be photovoltaic and wind power. Therefore, photovoltaics will become a major energy source in the future.

[0003] The silicon wafer segment is located in the mid-to-upstream of the photovoltaic industry chain. It not only supports the development of upstream silicon materials but also provides raw material solutions for the technological innovation and efficiency improvement of downstream cells and modules. Silicon wafers also account for a large proportion of the overall module cost structure, and cost reduction in silicon wafers plays a crucial role in the photovoltaic industry, contributing significantly to grid parity. High-quality silicon wafers are mainly characterized by low total thickness variance (TTV) and low wire marks. For large-size and thin wafers, low fragmentation, no edge chipping, bending, and warping also need to be considered. The development of the photovoltaic slicing segment will inevitably revolve around continuous technological innovation in the directions of "thinner," "larger," and "deformed" silicon wafers, and "higher cutting speed," "fineer wires," "higher quality," "lower cost," "automation," and "intelligentization." Diamond wire cutting fluid is an essential auxiliary material in this processing, and its performance directly affects the development and progress of the diamond wire slicing industry. Therefore, to specifically match the progress of larger and thinner silicon wafers and finer diamond wires, we have developed a high-performance water-based diamond wire cutting fluid. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of the present invention is that the silicon powder concentration generated during the cutting process of large-size silicon wafers using fine-diameter diamond wire is increased, the wear contact surface of the diamond wire participating in the cutting process is increased, the heat generated during the cutting process is increased, and the difficulty of water immersion at the cutting interface is increased. To address these problems, the present invention aims to improve the dispersion performance of the large amount of silicon powder generated during the cutting process of large-size silicon wafers; protect the wear of diamond particles on the surface of the diamond wire; and increase the water penetration between the cutting seams during the cutting process. This can better remove the fresh silicon powder and frictional heat generated during the cutting process, effectively reduce the problems of wire breakage and overcutting during the cutting process, and also better control the average TTV and wire mark values, as well as the yield of small indicators such as edge chipping and silicon drop, ensuring that the wafer yield is maintained at a high level.

[0005] To solve the above technical problems, the present invention is achieved through the following technical solution: This invention provides a cutting fluid for diamond wire cutting of large-size thin single-crystal silicon wafers. The cutting fluid for diamond wire multi-wire cutting of large-size thin single-crystal silicon wafers comprises the following components: 20%~30% of a wide molecular weight dispersant, 15%~22% of a wetting and penetrating agent, 8%~15% of a lubricating dispersant, and the balance being deionized water. The broad molecular weight dispersant is a polyoxyethylene polyoxypropylene ether with cyclohexanol as an initiator, wherein the molecular weight is controlled between 1000-5000, and the general chemical formula is as follows: ; Where 10≤x≤20, 20≤y≤40, 10≤z≤20, and x, y, and z are all integers; The wetting and penetrating agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where 3≤m≤5, 2≤n≤4, 5≤m+n≤8, and m and n are both integers; The wetting and dispersing agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where 8≤p≤12, 4≤q≤6, 12≤p+q≤18, and p and q are both integers.

[0006] Implementing the embodiments of the present invention has the following beneficial effects: 1) The dispersant used in this invention is a polyoxyethylene polyoxypropylene ether cis-block polyether structure with benzyl alcohol as the initiator. Its characteristics are that benzyl alcohol is single-ended, and its static and dynamic surface tensions are lower than those of conventional ethylene oxide and propylene oxide block polyethers. Cyclohexane, which has a certain rigidity, can provide a certain steric hindrance and enhance the dispersion performance. The main chain length of the ring structure is shorter than that of the straight chain structure with the same number of carbons, and its foaming performance is lower than that of the straight chain structure with the same number of carbons. When used at low concentrations, its foaming performance is comparable to that of ethylene oxide and propylene oxide block polyethers, and therefore it also has low foaming properties.

[0007] 2) In this invention, the polyethylene oxide and polypropylene oxide cis-block polyether in the dispersant has a wide molecular weight distribution. The wide distribution can provide a better emulsification effect. At the same time, a small amount of high molecular weight polyether has a large molecular weight and slow migration speed, which can fully replace the small molecule polyether on the surface of silicon powder in the cutting cylinder, ensuring that the effective concentration of small molecule polyether remains at a high level. This better helps to quickly disperse silicon powder during the cutting process and provides a more durable and faster silicon powder dispersion rate and efficiency.

[0008] 3) The wetting and penetrating agent of this invention uses polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator. The cycloalkane lipophilic group structure has the characteristics of large steric hindrance, less curling and lower foaming compared with the straight-chain lipophilic group of the same number of carbons. It can increase the number of carbons in the alcohol head, enhance the hydrophobicity of the lipophilic group, and reduce the surface tension of the wetting and penetrating agent. The number of polymerization units of propylene oxide and ethylene oxide can adjust the hydrophilic-lipophilic balance value (HLB value) and foaming performance. At a lower number of polymerization units, the dynamic surface tension can be effectively improved.

[0009] 4) This invention uses a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator for wetting and dispersing. It has the same starting alcohol head as the wetting and penetrating agent. The difference is that it has more ethylene oxide and propylene oxide polymer units than the wetting and dispersing agent. The surfactant with the same alcohol head structure has good compatibility and good consumption uniformity during use. At the same time, the dispersion effect increases with the increase of the amount of ethylene oxide. However, the foaming performance also increases with the increase of the number of ethylene oxide units. Therefore, propylene oxide segments are introduced to improve the foaming performance of the product.

[0010] 5) The cutting fluid of this invention has excellent dispersion and wetting properties. In the process of cutting large-size silicon wafers with fine-diameter diamond wire, it can exert excellent dispersion effect, wetting and liquid carrying performance, and silicon powder chip removal ability on the steel wire surface. Furthermore, by adjusting the number of polymerization units of ethylene oxide and propylene oxide, low foaming performance can be achieved without affecting the wetting effect. The alcohol head 3-methylcyclopentadecan-1-ol in the wetting penetrant and wetting dispersant can form a lubricating film layer on the silicon wafer surface, reducing the adhesion and adsorption force between silicon wafers after cutting, thereby reducing the lifting rod resistance and avoiding wire jamming and scratches on the silicon wafer surface. Detailed Implementation

[0011] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0012] The composition of the cutting fluid for diamond wire multi-wire dicing of large-size thin single-crystal silicon wafers is as follows: 25% molecular weight broad-distribution dispersant 20% wetting and penetrating agent 10% lubricating dispersant 45% deionized water The broad molecular weight dispersant is a polyoxyethylene polyoxypropylene ether with cyclohexanol as an initiator, wherein the molecular weight is controlled to be 1980~4500, and the general chemical formula is as follows: ; Where x=14, y=34, z=14; The wetting and penetrating agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where m=3, n=3; The wetting and dispersing agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where p=10 and q=5. Example

[0013] The composition of the cutting fluid for diamond wire multi-wire dicing of large-size thin single-crystal silicon wafers is as follows: 20% broad molecular weight dispersant 15% wetting and penetrating agent 8% lubricating dispersant 57% deionized water The broad molecular weight dispersant is a polyoxyethylene polyoxypropylene ether with cyclohexanol as an initiator, wherein the molecular weight is controlled between 1000-3000, and the general chemical formula is as follows: ; Where x=10, y=20, z=10; The wetting and penetrating agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where m=5, n=4; The wetting and dispersing agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: Where p=12 and q=6. Example

[0014] The composition of the cutting fluid for diamond wire multi-wire dicing of large-size thin single-crystal silicon wafers is as follows: 30% broad molecular weight dispersant 16% wetting and penetrating agent Lubricating dispersant 12% 42% deionized water The broad molecular weight dispersant is a polyoxyethylene polyoxypropylene ether with cyclohexanol as an initiator, wherein the molecular weight is controlled between 1500-3500, and the general chemical formula is as follows: ; Where x=12, y=24, z=12; The wetting and penetrating agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where m=5, n=2; The wetting and dispersing agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where p=8 and q=4. Example

[0015] The composition of the cutting fluid for diamond wire multi-wire dicing of large-size thin single-crystal silicon wafers is as follows: 30% broad molecular weight dispersant 22% wetting and penetrating agent 15% lubricating dispersant 39% deionized water The broad molecular weight dispersant is a polyoxyethylene polyoxypropylene ether with cyclohexanol as an initiator, wherein the molecular weight is controlled between 3000-5000, and the general chemical formula is as follows: ; Where x=20, y=38, z=20; The wetting and penetrating agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where m=4, n=3; The wetting and dispersing agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where p=11 and q=6. Example

[0016] The composition of the cutting fluid for diamond wire multi-wire dicing of large-size thin single-crystal silicon wafers is as follows: Broad molecular weight dispersant, 28%. 18% wetting and penetrating agent 9% lubricating dispersant 45% deionized water The broad molecular weight dispersant is a polyoxyethylene polyoxypropylene ether with cyclohexanol as an initiator, wherein the molecular weight is controlled between 1500-5000, and the general chemical formula is as follows: ; Where x=14, y=36, z=14; The wetting and penetrating agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where m=3, n=2; The wetting and dispersing agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ; Where p=8 and q=4.

[0017] The performance test conditions for the cutting fluid and commercially available cutting fluid in the example were as follows: the test wire cutting equipment was Yujing YJ-XQL921H type, the silicon rod specification was 210mm*210mm single crystal silicon wafer, the crystal rod type was N-type single crystal silicon rod, the rod length was 830mm, the wafer thickness was 130μm, the diamond wire busbar material was carbon steel, the busbar diameter was φ30μm, the single-blade cutting fluid addition amount was 1%, the cutting process conditions were the same, the cutting process time was 122 minutes, and the number of test cuts was 1000.

[0018] Table 1 Comparison of Silicon Wafer Cutting Yield Data ; According to the experimental results in Table 1, the A+B data and A-grade rate data of Examples 1 to 5 of the present invention have significant advantages over currently commercially available cutting fluid products. They also have significant advantages in comparing small index data (TTV, color difference, silicon shedding, line marks, dirt, etc.). Moreover, they have significant advantages in indicators such as wire jamming, additional cutting, and wire breakage. Among them, Example 5 is the best example.

[0019] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cutting fluid for cutting large-size thin single-crystal silicon wafers with diamond wire, characterized in that, The cutting fluid for cutting large-size thin silicon wafers with diamond wire fine wire comprises the following components: 20%~30% of a wide molecular weight dispersant, 15%~22% of a wetting and penetrating agent, 8%~15% of a lubricating dispersant, and the balance being deionized water; The broad molecular weight dispersant is a polyoxyethylene polyoxypropylene ether with cyclohexanol as an initiator, wherein the molecular weight is controlled between 1000-5000, and the general chemical formula is as follows: ； Where 10≤x≤20, 20≤y≤40, 10≤z≤20, and x, y, and z are all integers; The wetting and penetrating agent is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ； Where 3≤m≤6, 3≤n≤5, 6≤m+n≤8, and m and n are both integers; The lubricating dispersant is a polyoxyethylene polyoxypropylene ether with 3-methylcyclopentadecan-1-ol as the initiator, and its general chemical formula is as follows: ； Where 5≤p≤8, 0≤q≤2, 6≤p+q≤9, and p and q are both integers.

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