A cutting fluid suitable for large-size ultra-thin silicon wafers and a preparation method thereof

Abstract

This invention discloses a cutting fluid suitable for large-size ultra-thin silicon wafers and its preparation method. The cutting fluid comprises the following components by mass percentage: 20-50% functional lubricating dispersant, 10-30% low-foaming wetting agent, 0.5-5% defoamer, 0.1-2% stabilizer, and the balance being pure water. The cutting fluid for large-size ultra-thin silicon wafers of this invention exhibits outstanding wetting, dispersing, lubricating, and chip removal properties. It has low foaming, rapid defoaming, and is environmentally friendly. It is suitable for cutting large-size, ultra-thin silicon wafers, significantly reducing diamond wire breakage rate and TTV value, and solving problems such as color difference, wire marks, and edge chipping in the large-size, thin-wafer cutting process. This invention also discloses a method for preparing the above-mentioned cutting fluid for large-size ultra-thin silicon wafers.

Description

Technical Field

[0001] This invention relates to the field of diamond wire silicon wafer cutting technology, and in particular to a cutting fluid suitable for large-size ultra-thin silicon wafers and its preparation method. Background Technology

[0002] In recent years, the photovoltaic industry has developed rapidly, with a surge in demand for photovoltaic silicon wafers, driving continuous iteration of diamond wire silicon wafer cutting technology. Silicon wafer cutting is one of the core processes in silicon wafer manufacturing; its processing technology and quality directly affect the entire silicon wafer production process and subsequent cell manufacturing, and also directly impact cell performance. Cutting fluid plays a role in lubrication, cooling, and cleaning during silicon wafer cutting. It also disperses and removes silicon powder generated during cutting, providing a certain degree of wetting to the diamond wire and silicon wafer, effectively protecting the diamond wire, ensuring smooth cutting, significantly reducing the probability of wire breakage, and guaranteeing the yield of cut products.

[0003] The increasing size and thinning of silicon wafers are indicators of advancements in silicon wafer cutting technology and cost reduction. Larger sizes reduce manufacturing costs and increase module power output, while thinner wafers reduce wafer usage and production costs. Currently, mainstream silicon wafer sizes have upgraded from 166mm to larger sizes, primarily 182mm and 210mm, and wafer thicknesses have also iterated from 180μm and 150μm to 130μm, 120μm, and 110μm. Cutting larger wafers significantly increases the risk of fragmentation, while cutting ultra-thin wafers generates more silicon powder, which is unevenly dispersed or not carried out in time, making it difficult to control wafer yield. This innovative iteration places extremely high demands on the cutting fluid. Currently, the diamond wire cutting fluids used in the market do not have outstanding overall performance. Although they have improved the problems of difficult silicon powder dispersion and difficulty in wetting the cutting seam to some extent, issues such as wire breakage, color difference, wire marks, edge chipping, and TTV have not been significantly improved, resulting in low yield and difficulty in meeting the requirements of cutting-edge technology. Therefore, there is an urgent need to develop a cutting fluid suitable for large-size ultra-thin silicon wafers that can effectively solve the above problems. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem solved by the present invention is to provide a cutting fluid suitable for large-size ultra-thin silicon wafers and its preparation method. The large-size ultra-thin silicon wafer cutting fluid provided by the present invention has outstanding wetting, dispersing, lubricating, and chip removal properties; it has low foaming, rapid defoaming, and is environmentally friendly. It is suitable for cutting large-size, ultra-thin silicon wafers, and can significantly reduce diamond wire breakage rate and TTV value, solving problems such as color difference, wire marks, and edge chipping in the large-size, thin-wafer cutting process. The present invention also provides a method for preparing the above-mentioned large-size ultra-thin silicon wafer cutting fluid.

[0005] To address the aforementioned technical problems, this invention provides a cutting fluid suitable for large-size ultrathin silicon wafers, comprising the following components by mass percentage:

[0006]

[0007] As a preferred embodiment of the above technical solution, the cutting fluid for large-size ultra-thin silicon wafers provided by the present invention further includes some or all of the following technical features:

[0008] As an improvement to the above technical solution, the functional lubricating dispersant is a fatty alcohol random polyether synthesized from at least two of monohydroxy, dihydroxy, and polyhydroxy fatty alcohols, with the following structural formula:

[0009]

[0010] Where R is a C4-C10 alkyl group, R1 and R3 are -CH-, R2 is -CH-, -CH2- or -CH2-CH2-CH2-CH2-, R4 and R5 are -H or -CH3, R6 is two of -H and -CH3, the mass ratio of -H / -CH3 in R6 is 0.5 to 2.0, m1 and m2 are 10 to 80, and n is 0 to 1.

[0011] As a preferred embodiment of the above technical solution, the low-foaming wetting agent is at least two of the following: decantyne glycol polyoxyethylene ether or dodecyne glycol polyoxyethylene ether, and branched alcohol block polyether. The structural formula of the branched alcohol block polyether is as follows:

[0012]

[0013] Where R is 2,6,8-trimethyl-4-nonyl, m is 3 to 10, n is 2 to 6, and p is 0 to 5.

[0014] As a preferred embodiment of the above technical solution, the conductivity of the 10% aqueous solution of the functional lubricating dispersant is ≤10 μS / cm, and the conductivity of the 10% aqueous solution of the low-foaming wetting agent is ≤10 μS / cm.

[0015] As a preferred embodiment of the above technical solution, the defoamer is an acetylenic diol defoamer, one or more of TL-104E, TL-110D, TL-110BC, and TL-110DPG.

[0016] As a preferred embodiment of the above technical solution, the stabilizer is ethylenediamine polyoxyethylene polyoxypropylene ether, with the following structural formula:

[0017]

[0018] Where m is 0 to 2 and n is 0 to 2.

[0019] A method for preparing a cutting fluid suitable for large-size ultrathin silicon wafers as described above, comprising the following steps:

[0020] (S1) After cleaning the reactor, add pure water and start stirring; the washing water should meet the requirements of COD≤100 and foam height 0ml;

[0021] (S2) Add the functional lubricating dispersant, low-foaming wetting agent, defoamer, and stabilizer in sequence, and stir continuously;

[0022] (S3) The temperature of the reactor is controlled at 30-60℃. Stir for 2-4 hours until the added material is completely dissolved and becomes a transparent and homogeneous liquid.

[0023] (S4) Cool down to below 30°C and filter to obtain a cutting fluid suitable for large-size ultra-thin silicon wafers.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] The functional lubricant and dispersant of this invention is a fatty alcohol random polyether synthesized from at least two of monohydroxy, dihydroxy, and polyhydroxy fatty alcohols. Its composite structure provides excellent synergistic effects on dispersion, lubrication, wetting, and system compatibility. Furthermore, the random polyether segments consist of ethylene oxide (EO) and propylene oxide (PO) arranged randomly on the molecular chain, unlike block polyethers which form longer individual segments. Its comb-like structure contains more anchoring groups, resulting in better stability, superior silicon powder dispersion and lubrication capabilities, and significant low-foaming properties. Therefore, it effectively prevents the aggregation and agglomeration of silicon powder, metals, and organic impurities generated during the cutting of large-size thin silicon wafers, preventing adhesion to the wafer surface and blockage of channels, effectively improving slicing yield and reducing the difficulty of silicon wafer cleaning and wastewater treatment.

[0026] The low-foaming wetting agent of this invention is at least two of the following: decantyne glycol polyoxyethylene ether, dodecantyne glycol polyoxyethylene ether, and branched alcohol block polyether. All belong to the hyperbranched polyether structure, have low hydrophobic carbon chain cohesion, significantly reduced dynamic and static surface tension, low foaming and rapid defoaming, and excellent wetting and penetration capabilities. It can quickly wet the silicon powder generated during cutting, as well as the diamond wire and silicon wafer surface, promptly carrying away the heat generated by high-speed cutting, reducing silicon powder residue, lowering the diamond wire breakage rate, and minimizing damage to the silicon wafer surface.

[0027] The stabilizer of this invention is ethylenediamine polyoxyethylene polyoxypropylene ether, which has the function of complexing metals and balancing pH value. Through complexation, it can eliminate metal particles generated during the cutting process and eliminate the impact on the subsequent silicon wafer texturing and cleaning process. In addition, it can maintain the acid-base balance of the system and maintain the charge balance of the cutting fluid system to achieve optimal cutting efficiency.

[0028] The silicon wafer cutting fluid of the present invention has outstanding wetting, dispersing, lubricating and chip removal properties, as well as excellent foam control ability, low electrical conductivity and green environmental protection. It can significantly reduce the diamond wire breakage rate and TTV value, and solve the problems of color difference, wire marks and edge chipping in the cutting process of large size and thin wafers. It can be used for cutting silicon wafers with a size of 182mm or more and a thickness of 150μm or less.

[0029] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, the following detailed description is provided in conjunction with preferred embodiments. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be described in full below. 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.

[0031] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the invention in any way.

[0032] In the following embodiments, the functional lubricating dispersant has the following general structural formula:

[0033]

[0034] Where R is a C4 to C10 alkyl group, R1 and R3 are -CH-, R2 is -CH-, -CH2- or -CH2-CH2-CH2-CH2-, R4 and R5 are -H or -CH3, R6 is two of -H and -CH3, the mass ratio of -H / -CH3 in R6 is 0.5 to 2.0, m1 and m2 are 10 to 80, and n is 0 to 1.

[0035] In the following embodiments, the general formula of the branched alcohol block polyether structure is as follows:

[0036]

[0037] Where R is 2,6,8-trimethyl-4-nonyl, m is 3 to 10, n is 2 to 6, and p is 0 to 5.

[0038] In the following embodiments, the general structural formula of the stabilizer ethylenediamine polyoxyethylene polyoxypropylene ether is as follows:

[0039]

[0040] Where m is 0 to 2 and n is 0 to 2.

[0041] Example 1:

[0042] A cutting fluid suitable for large-size ultra-thin silicon wafers comprises the following components by weight percentage:

[0043] 35% functional lubricating dispersant

[0044] Where R is a C4 alkyl group, the mass ratio of -H / -CH3 in R6 is 1.05, m1 is 62, and the mass percentage is 20%; where R1 and R3 are -CH-, R2 is -CH2-, R4 and R5 are -H, the mass ratio of -H / -CH3 in R6 is 1.05, m2 is 30, n is 0, and the mass percentage is 15%.

[0045] Low-foaming wetting agent 20%.

[0046] Among them, the decynyl diol polyoxyethylene ethers are TL-J40 and TL-J65A, with a mass ratio of 6% and 10%, respectively; in the branched alcohol block polyether, R is 2,6,8-trimethyl-4-nonyl, m is 5, n is 3, p is 0, and the mass ratio is 4%.

[0047] Defoamer 1.0%.

[0048] The mass percentages of TL-104E and TL-110DPG were 0.2% and 0.8%, respectively.

[0049] Stabilizer 0.5%.

[0050] In this case, ethylenediamine polyoxyethylene polyoxypropylene ether has m = 0 and n = 1.

[0051] The remainder is pure water.

[0052] The preparation method of this embodiment includes the following steps: (S1) After cleaning the reactor, add pure water and start stirring; the washing water meets the requirements of COD≤100 and foam height of 0ml; (S2) Add functional lubricating dispersant, low foaming wetting agent, defoamer and stabilizer in sequence, and stir continuously; (S3) Control the temperature of the reactor at 30-60℃, stir for 2-4 hours until the added materials are completely dissolved and become a transparent and homogeneous liquid; (S4) Cool down to below 30℃, and after filtration, obtain a cutting fluid suitable for large-size ultra-thin silicon wafers.

[0053] Example 2:

[0054] A cutting fluid suitable for large-size ultra-thin silicon wafers comprises the following components by weight percentage:

[0055] Functional lubricating dispersant 30%.

[0056] Where R is a C8 alkyl group, the mass ratio of -H / -CH3 in R6 is 1.0, m1 is 55, and the mass percentage is 25%; where R1 and R3 are -CH-, R2 is -CH2-, R4 and R5 are -H, the mass ratio of -H / -CH3 in R6 is 0.9, m2 is 25, n is 1, and the mass percentage is 5%.

[0057] Low-foaming wetting agent 18%.

[0058] Among them, decynylene glycol polyoxyethylene ether is TL-J65A and dodecynylene glycol polyoxyethylene ether is TL-604, with a mass ratio of 10% and 4% respectively; in the branched alcohol block polyether, R is 2,6,8-trimethyl-4-nonyl, m is 4, n is 4, p is 2, with a mass ratio of 4%.

[0059] Defoamer 1.3%.

[0060] The mass percentages of TL-110D and TL-110BC were 0.3% and 1.0%, respectively.

[0061] Stabilizer 0.8%.

[0062] In this case, ethylenediamine polyoxyethylene polyoxypropylene ether has m = 1 and n = 1.

[0063] The remainder is pure water.

[0064] The preparation method in this embodiment is the same as in Embodiment 1.

[0065] Example 3:

[0066] A cutting fluid suitable for large-size ultra-thin silicon wafers comprises the following components by weight percentage:

[0067] Functional lubricant dispersant 28%.

[0068] Where R is a C4 alkyl group, the mass ratio of -H / -CH3 in R6 is 1.2, m1 is 48, and the mass percentage is 18%; where R1 and R3 are -CH-, R2 is -CH2-CH2-CH2-CH2-, R4 and R5 are -H, the mass ratio of -H / -CH3 in R6 is 0.8, m2 is 36, n is 0, and the mass percentage is 10%.

[0069] Low-foaming wetting agent 22%

[0070] Among them, decynylene glycol polyoxyethylene ether is TL-J40 and dodecynylene glycol polyoxyethylene ether is TL-607, with a mass ratio of 5% and 10% respectively; in the branched alcohol block polyether, R is 2,6,8-trimethyl-4-nonyl, m is 6, n is 4 and p is 3, with a mass ratio of 5%.

[0071] Defoamer 1.7%.

[0072] The mass percentages of TL-104E and TL-110BC were 0.2% and 1.5%, respectively.

[0073] Stabilizer 0.5%.

[0074] In this case, ethylenediamine polyoxyethylene polyoxypropylene ether has m = 1 and n = 0.

[0075] The remainder is pure water.

[0076] The preparation method in this embodiment is the same as in Embodiment 1.

[0077] Example 4:

[0078] A cutting fluid suitable for large-size ultra-thin silicon wafers comprises the following components by weight percentage:

[0079] Functional lubricating dispersant 32%.

[0080] Where R is a C10 alkyl group, the mass ratio of -H / -CH3 in R6 is 0.95, m1 is 60, and the mass percentage is 22%; where R1 and R3 are -CH-, R2 is -CH2-, R4 and R5 are -H, the mass ratio of -H / -CH3 in R6 is 1.1, m2 is 27, n is 0, and the mass percentage is 10%.

[0081] Low-foaming wetting agent 20%

[0082] Among them, dodecynediol polyoxyethylene ether is TL-604 and TL-607, with a mass ratio of 3% and 12% respectively; in the branched alcohol block polyether, R is 2,6,8-trimethyl-4-nonyl, m is 3, n is 3, p is 1, and the mass ratio is 5%.

[0083] Defoamer 1.5%.

[0084] The mass percentages of TL-110D and TL-110DPG were 0.3% and 1.2%, respectively.

[0085] Stabilizer 1.0%.

[0086] In this case, ethylenediamine polyoxyethylene polyoxypropylene ether has m = 1 and n = 1.

[0087] The remainder is pure water.

[0088] The preparation method in this embodiment is the same as in Embodiment 1.

[0089] Comparative Examples 1-3 are three commercially available products of the same type.

[0090] Table 1 Test results of Examples 1-4 and Comparative Examples 1-3

[0091]

[0092] Examples 1-4 and Comparative Examples 1-3 all used the same equipment and process, and were diluted with pure water at a ratio of 1-300 to conduct cutting experiments on silicon wafers with a size of 210 mm and a thickness of 150 μm.

[0093] Examples 1-4 can significantly reduce the diamond wire breakage rate and TTV value, improve the A-grade yield, and solve problems such as silicon shedding, contamination, wire marks, edge chipping, and color difference in the large-size, thin-wafer cutting process. Furthermore, the silicon wafer cutting fluid of this invention not only has outstanding wetting, dispersing, lubricating, and chip removal properties, but also excellent foam control capabilities, low conductivity, and is environmentally friendly with low wastewater treatment difficulty, meeting the trend requirements of large-size, thin-wafer cutting.

[0094] All the raw materials listed in this invention, as well as the upper and lower limits and ranges of the raw materials and the upper and lower limits and ranges of the process parameters (such as temperature, time, etc.), can realize this invention. Examples are not listed one by one here.

[0095] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A cutting fluid suitable for large-size ultra-thin silicon wafers, characterized in that, Includes the following components by mass percentage: Functional lubricating dispersant 20-50%; Low-foaming wetting agent: 10-30%; Defoamer 0.5-5%; Stabilizer 0.1~2%; The remainder is pure water; The low-foaming wetting agent is at least two of the following: decantyne glycol polyoxyethylene ether or dodecyne glycol polyoxyethylene ether, and branched alcohol block polyether. The structural formula of the branched alcohol block polyether is as follows: Where R is 2,6,8-trimethyl-4-nonyl, m is 3~10, n is 2~6, and p is 0~5; The stabilizer is ethylenediamine polyoxyethylene polyoxypropylene ether, with the following structural formula: Where m is 0~2 and n is 0~2.

2. The cutting fluid for large-size ultra-thin silicon wafers as described in claim 1, characterized in that: The functional lubricating dispersant is a fatty alcohol random polyether synthesized from at least two of monohydroxy, dihydroxy, and polyhydroxy fatty alcohols, with the following structural formula: or Where R is a C4-C10 alkyl group, R1 and R3 are -CH-, R2 is -CH-, -CH2- or -CH2-CH2-CH2-CH2-, R4 and R5 are -H or -CH3, R6 is either -H or -CH3, the mass ratio of -H / -CH3 in R6 is 0.5~2.0, m1 and m2 are 10~80, and n is 0~1.

3. The cutting fluid for large-size ultra-thin silicon wafers as described in claim 1, characterized in that: The conductivity of the functional lubricating dispersant in a 10% aqueous solution is ≤10 μS / cm, and the conductivity of the low-foaming wetting agent in a 10% aqueous solution is ≤10 μS / cm.

4. The cutting fluid for large-size ultra-thin silicon wafers as described in claim 1, characterized in that: The defoamer is an acetylenic diol defoamer, one or more of TL-104E, TL-110D, TL-110BC, and TL-110DPG.

5. A method for preparing a cutting fluid suitable for large-size ultrathin silicon wafers as described in any one of claims 1-4, characterized in that, It includes the following steps: (S1) After cleaning the reactor, add pure water and start stirring; (S2) Add the functional lubricating dispersant, low-foaming wetting agent, defoamer, and stabilizer in sequence, and stir continuously; (S3) The temperature of the reactor is controlled at 30~60℃, and the mixture is stirred for 2~4 hours until the added material is completely dissolved and becomes a transparent and homogeneous liquid; (S4) Cool down to below 30°C and filter to obtain a cutting fluid suitable for large-size ultra-thin silicon wafers.

6. The method for preparing the cutting fluid suitable for large-size ultra-thin silicon wafers as described in claim 5, characterized in that: In step (S1), the washing water meets the requirements of COD≤100 and foam height is 0ml.

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