Water-soluble scribing liquid for wafer blade cutting and preparation method of water-soluble scribing liquid

Abstract

According to the water-soluble scribing liquid for wafer blade cutting and the preparation method of the water-soluble scribing liquid, the ionic liquid is introduced to achieve the synergistic effect with the anionic surfactant and the Gemini cationic surfactant, the interfacial tension of a blade and a wafer can be effectively reduced, scratches and damage to the surface of the blade and the surface of the wafer are reduced, and in addition, the water-soluble scribing liquid can be used for wafer blade cutting. The polar groups can adsorb chips through the electrostatic interaction, coalescence and removal are carried out through the micelle compatibilization effect of the surfactant, the chips are prevented from being adsorbed on the surfaces of the blade and the wafer, and the blade and the wafer are prevented from rusting in the machining process.

Description

Technical Field

[0001] This invention belongs to the field of wafer processing technology, and specifically relates to a water-soluble dicing solution for wafer blade cutting and its preparation method. Background Technology

[0002] During wafer fabrication, intense friction occurs between the cutting tool and the wafer, generating static electricity, vibration, a large amount of heat, and debris. This can easily lead to edge chipping and corner breakage, blade wear and breakage, debris adhesion, corrosion, and rust. Therefore, dicing fluid is generally added during wafer fabrication to provide multiple functions such as cooling, lubrication, cleaning, rust prevention, and vibration damping. This ensures high efficiency and quality in the processing, absorbs and dissipates heat to prevent wafer damage due to overheating, reduces friction between the cutting tool and the wafer, thereby reducing blade wear and extending tool life, and minimizing scratches and damage to the wafer surface. It also removes debris and dust generated during the cutting process, keeping the cutting area clean and preventing these debris from affecting cutting accuracy and quality. Furthermore, it absorbs some vibration during the cutting process, improving cutting stability and accuracy, and preventing the cutting tool and wafer from rusting during processing.

[0003] Existing scribing solutions are generally water-based, with various functional additives added to the aqueous solution to improve their effectiveness. For example, CN 107142145 A describes a scribing solution composed of 1%-3% surfactant, 0.5%-1.5% extreme pressure agent, 4%-6% lubricant, and the balance being deionized water. The surfactant is a phosphate ester surfactant, sodium dodecylbenzenesulfonate, or coconut oil fatty acid diethanolamide; the extreme pressure agent is octylphenol polyoxyethylene ether; and the lubricant is polyethylene glycol 400. By adding surfactants, good lubrication is achieved while increasing wetting and preventing edge chipping; the addition of extreme pressure agents can better prevent fragment breakage and effectively increase the yield of the cutting process. CN 103113972A describes a dicing solution composed of 2%-7% of either polyethylene glycol or polyvinyl alcohol (molecular weight between 2000 and 20000), or a mixture of these two polymers with different molecular weights; 0.001%-0.5% of a polysiloxane surfactant or a phosphate surfactant; and 0.01%-0.5% of a quinoline or thiazole agent. The polysiloxane surfactant or the phosphate surfactant has at least two branches in its lipophilic group. This dicing solution can reduce debris and contamination generated during the dicing process, while also slowing down the corrosion of the solder pads. However, silicone or phosphate surfactants are extremely foaming and produce abundant foam. Excessive foam can inhibit the adsorption of the surfactant on the cutting blade and its contact surface with the wafer, as well as the effect of reducing interfacial tension. Therefore, defoamers are usually added. However, the addition of defoamers can easily lead to reduced stability of the dicing solution and even precipitation and stratification. Summary of the Invention

[0004] To overcome the problems existing in the prior art, the purpose of this invention is to provide a water-soluble dicing solution for wafer cutting and its preparation method. By introducing ionic liquids and anionic surfactants and Gemini cationic surfactants, the interfacial tension between the blade and the wafer can be effectively reduced, thereby reducing scratches and damage to the blade and wafer surfaces. Furthermore, the polar groups can adsorb debris through electrostatic interaction and aggregate and remove it through the micellar compressive effect of the surfactants, preventing debris from adsorbing on the blade and wafer surfaces and preventing the blade and wafer from rusting during processing.

[0005] The objective of this invention is achieved through the following technical solution: A water-soluble dicing solution for wafer cutting comprises 1-6% anionic surfactant, 1-3% Gemini cationic surfactant, 0.5-2% ionic liquid, 0.5-3% polyethylene glycol, and the balance being deionized water.

[0006] Preferably, the Gemini cationic surfactant is a hyperbranched Gemini cationic surfactant.

[0007] Preferably, the hyperbranched Gemini cationic surfactant includes one or more of symmetrical alkyl hyperbranched Gemini cationic surfactants and asymmetrical hyperbranched Gemini cationic surfactants.

[0008] Preferably, the hyperbranched Gemini cationic surfactant includes one or more of C12-18 dialkyltrimethylammonium chloride, C12-18 dialkylimidazoline ammonium chloride, and C12-18 dialkylpyridine ammonium chloride.

[0009] Preferably, the ionic liquid is one or more of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0010] Preferably, the ionic liquid is one or both of 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and 1-hexyl-3-methylimidazolium hexafluorophosphate.

[0011] Preferably, the anionic surfactant comprises one or more of C12-18 alkyl sulfate, C12-18 alkylbenzene sulfonate, C12-18 alkyl sulfosuccinate, C12-18 alkyl carboxylate, and C12-18 alkyl sulfonate.

[0012] Preferably, the anionic surfactant includes one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dioctyl sulfosuccinate, and sodium stearate.

[0013] A method for preparing a water-soluble dicing solution for wafer cutting includes the following reaction steps: Step 1: Weigh each component according to the mass ratio; Step 2: Mix Gemini cationic surfactant, anionic surfactant, ionic liquid, and deionized water, heat to 30-45℃, and stir for 10-30 minutes; Step 3: Add polyethylene glycol PEG4000 to the aqueous solution from Step 2 and continue stirring for 10-30 minutes to obtain a water-soluble streak solution.

[0014] The present invention has achieved the following beneficial effects: 1) The introduction of ionic liquids, in synergy with anionic surfactants and Gemini cationic surfactants, forms a dense interface layer with oriented arrangement on the surface of the cutting tool and wafer. This effectively reduces interfacial tension, thereby reducing scratches and damage to the surface of the cutting tool and wafer. Furthermore, the polar groups can adsorb debris through electrostatic interaction and aggregate and remove it through the micellar compressive effect of the surfactants, preventing debris from adsorbing on the surface of the cutting tool and wafer and preventing the cutting tool and wafer from rusting during processing.

[0015] 2) Hyperbranched Gemini cationic surfactants are used. Through their long alkyl chains and branched structure, they provide a three-dimensional network structure, which improves the adsorption capacity of debris, prevents debris from adsorbing on the blade and wafer surface, and prevents the blade and wafer from rusting during processing. Detailed Implementation

[0016] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0017] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0018] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means. Example

[0019] A water-soluble dicing solution for wafer cutting comprises 3% by weight of anionic surfactant sodium dodecyl sulfate, 1% by weight of hyperbranched Gemini cationic surfactant, 1.5% by weight of ionic liquid 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 2% by weight of polyethylene glycol PEG4000, and the balance being deionized water. The hyperbranched Gemini cationic surfactant is a hyperbranched Gemini quaternary ammonium salt propylene [(dodecyl polyoxyethylene / octadecyl polyoxyethylene) chloride / ammonium bromide].

[0020] The preparation method of the above-mentioned water-soluble scrubbing solution includes the following reaction steps: Step 1: Weigh each component according to the mass ratio; Step 2: Mix the hyperbranched Gemini cationic surfactant, sodium dodecyl sulfate, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and deionized water, heat to 35°C, and stir for 20 minutes; Step 3: Add polyethylene glycol PEG4000 to the aqueous solution from Step 2 and continue stirring for 15 minutes to obtain a water-soluble streak solution.

[0021] A water-soluble dicing solution for wafer cutting blades is prepared according to the method of Example 1, except that the anionic surfactant sodium dodecyl sulfate is replaced with the cationic surfactant dodecyltrimethylammonium chloride.

[0022] A water-soluble dicing solution for wafer cutting blades is prepared according to the method of Example 1, the only difference being that the ionic liquid 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is replaced with the anionic surfactant sodium dodecyl sulfate.

[0023] A water-soluble dicing solution for wafer cutting blades is prepared according to the method of Example 1, the only difference being that the hyperbranched Gemini quaternary ammonium salt propene group [(dodecyl polyoxyethylene / octadecyl polyoxyethylene) chloride / ammonium bromide] is replaced with the anionic surfactant sodium dodecyl sulfate.

[0024] A water-soluble dicing solution for wafer cutting blades is prepared according to the method of Example 1, the only difference being that the hyperbranched Gemini quaternary ammonium salt propylene group [(dodecyl polyoxyethylene / octadecyl polyoxyethylene) chloride / ammonium bromide] is replaced with propylene group (dodecyl dimethyl ammonium chloride / octadecyl dimethyl ammonium chloride).

[0025] The water-soluble dicing solutions for wafer cutting obtained in Example 1 and Comparative Examples 1-4 were characterized as follows: Surface tension: The dynamic surface tension was tested using a dynamic surface tension tester. Deionized water at room temperature was used as calibration. The sample was diluted 1000 times with deionized water and the dynamic surface tension was tested for 1000 ms at room temperature.

[0026] Particle residue: The sample to be tested was diluted 1000 times with deionized water and cut with a wafer dicing machine. After cutting, the surface particle residue and damage were observed with a microscope.

[0027] Table 1. Performance of water-soluble dicing solution for wafer cutting Surface tension / mN / m Particle residue Number of cracks / cm Crack length / µm Example 1 21.76 none 2 3 Comparative Example 1 25.48 small amount 4 7 Comparative Example 2 23.39 small amount 3 8 Comparative Example 3 27.14 small amount 4 7 Comparative Example 4 26.35 small amount 3 5 A comparison of Examples 1, 1, 2, and 3 shows that the water-soluble scribing solution prepared in Example 1 of this application exhibits superior performance in terms of surface tension, particle residue, crack number, and length. This is likely because the ionic liquid, anionic surfactant, and Gemini cationic surfactant all possess both hydrophilic and hydrophobic groups. Their synergistic effect forms a densely packed, oriented interface layer on the blade and wafer surface, effectively reducing interfacial tension, minimizing scratches and damage to the blade and wafer surface, inhibiting crack generation and growth during processing, and reducing crack length. The quantity and length of the debris are also reduced, which also inhibits the adsorption of debris. On the other hand, the cationic polar groups can adsorb negatively charged silicon debris through electrostatic interaction, and the anionic polar groups can adsorb positively charged metal debris through electrostatic interaction. In particular, the ionic liquid 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt has abundant positive and negative charges and polar groups, which can improve the adsorption effect on debris. It can also promote the aggregation and removal of debris through the micellar compressive effect of surfactants, prevent the adsorption of debris on the blade and wafer surface, and inhibit the generation and growth of cracks and surface particle residues during processing.

[0028] As can be seen from the comparison between Example 1 and Comparative Example 4, the water-soluble scribing solution prepared in Example 1 of this application has better effects in terms of surface tension, particle residue, number and length of cracks. This may be because Example 1 uses hyperbranched Gemini cationic surfactant propylene group [(dodecyl polyoxyethylene / octadecyl polyoxyethylene) chloride / ammonium bromide], while Comparative Example 4 uses conventional Gemini cationic surfactant propylene group (dodecyl dimethyl ammonium chloride / octadecyl dimethyl ammonium chloride). Propylene group [(dodecyl polyoxyethylene / octadecyl polyoxyethylene) chloride / ammonium bromide] has a hyperbranched structure compared to propylene group (dodecyl dimethyl ammonium chloride / octadecyl dimethyl ammonium chloride). The long alkyl chain and hyperbranched structure provide a three-dimensional network structure, which can further improve the adsorption capacity of debris, prevent debris from adsorbing on the blade and wafer surface, inhibit the generation and growth of cracks and surface particle residue during processing, and prevent the blade and wafer from rusting during processing.

[0029] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A water-soluble dicing solution for wafer cutting, comprising 1-6% anionic surfactant, 1-3% Gemini cationic surfactant, 0.5-2% ionic liquid, 0.5-3% polyethylene glycol, and the balance being deionized water; wherein the Gemini cationic surfactant is a hyperbranched Gemini cationic surfactant.

2. The water-soluble dicing solution for wafer cutting according to claim 1, characterized in that, The hyperbranched Gemini cationic surfactant includes one or more of symmetrical alkyl hyperbranched Gemini cationic surfactants and asymmetrical hyperbranched Gemini cationic surfactants.

3. The water-soluble dicing solution for wafer cutting according to claim 1, characterized in that, The hyperbranched Gemini cationic surfactant includes one or more of C12-18 dialkyltrimethylammonium chloride, C12-18 dialkylimidazoline ammonium chloride, and C12-18 dialkylpyridinium chloride.

4. The water-soluble dicing solution for wafer cutting according to claim 1, characterized in that, The hyperbranched Gemini cationic surfactant is propylene [(dodecyl polyoxyethylene / octadecyl polyoxyethylene) chloride / ammonium bromide].

5. The water-soluble dicing solution for wafer cutting according to claim 1, characterized in that, The ionic liquid is one or more of the following: 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

6. The water-soluble dicing solution for wafer cutting according to claim 1, characterized in that, The ionic liquid is one or both of 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and 1-hexyl-3-methylimidazolium hexafluorophosphate.

7. The water-soluble dicing solution for wafer cutting according to claim 1, characterized in that, The anionic surfactant includes one or more of C12-18 alkyl sulfate, C12-18 alkylbenzene sulfonate, C12-18 alkyl sulfosuccinate, C12-18 alkyl carboxylate, and C12-18 alkyl sulfonate.

8. The water-soluble dicing solution for wafer cutting according to claim 1, characterized in that, The anionic surfactant includes one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dioctyl sulfosuccinate, and sodium stearate.

9. A method for preparing the water-soluble dicing solution for wafer cutting according to any one of claims 1-8, comprising the following reaction steps: Step 1: Weigh each component according to the mass ratio; Step 2: Mix Gemini cationic surfactant, anionic surfactant, ionic liquid, and deionized water, heat to 30-45℃, and stir for 10-30 minutes; Step 3: Add polyethylene glycol PEG4000 to the aqueous solution from Step 2 and continue stirring for 10-30 minutes to obtain a water-soluble streak solution.