Bump chip ultrasonic spray laser protection fluid, preparation method, application and spraying method

Abstract

The present application relates to a kind of bump chip ultrasonic wave spray laser protection fluid, preparation method, application and the spray laser cutting protection method using it, the protection fluid includes water-soluble resin, ultraviolet absorber, organic solvent, auxiliary agent and ultrapure water, wherein by containing using water-soluble resin with lower viscosity and excellent water-solubility, can be realized under the premise of low resin content and low dosage to wafer and bump surface formation uniform and comprehensive coverage, and by using specific auxiliary agent, very beneficial to the spreading of atomized droplets on wafer surface, can promote good contact between wafer and the molecules of film layer, further improve the adhesion of film layer on wafer, with good synergy with polyester.Therefore the protection fluid is particularly suitable for bump chip ultrasonic spray laser cutting protection, it has profound significance in the field of semiconductor chip processing and packaging.

Description

Technical Field

[0001] This invention relates to a composition used in semiconductor processing, a preparation method thereof, its uses, and a spraying method thereof. More specifically, it relates to multiple technical solutions, including an ultrasonic spraying laser protective liquid for bump chips, its preparation method, its application, and a spraying laser cutting protection method thereof, belonging to the fields of semiconductor processing technology and packaging technology. Background Technology

[0002] The dicing process in semiconductor chip packaging typically includes four steps: film application, wafer grinding, laser grooving, and dicing. Before laser grooving, a laser protective solution is applied to the wafer surface to effectively prevent the influence of impurities such as silicon slag, oxides, or molten metal, reducing the heat-affected zone (HAZ) during the cutting process and thus improving the yield of laser cutting.

[0003] Currently, the laser protective liquid is mostly applied by centrifugal spin coating in this operation. This coating method is relatively simple and convenient, and has thus become the mainstream process.

[0004] With the rapid development of the semiconductor packaging field and the increasing demands on process technology, some wafers have bumps with a height of >100μm. The top of such bumps is very smooth. Under the influence of gravity, the laser protective liquid applied by spin coating process is difficult to form a uniform covering film on the top of the bump. As a result, it is impossible to effectively avoid the influence of impurities such as silicon slag and oxides. This has become a technical difficulty and defect in the current packaging field.

[0005] Ultrasonic spraying is a coating method based on ultrasonic atomizing nozzle technology. It uses an ultrasonic atomizing device to atomize a protective liquid into fine particles, which are then uniformly coated onto the substrate surface with a certain amount of carrier gas, forming a protective film. Compared to traditional spin coating methods such as centrifugal spin coating, ultrasonic spraying offers greater flexibility and controllability. The coating thickness can be controlled between tens of nanometers and several micrometers, and it exhibits better uniformity and precision, significantly improving coating accuracy and product yield.

[0006] However, existing laser protective liquids have high viscosity, which easily clogs the nozzles and damages the machine, making ultrasonic spraying unsuitable. While reducing the resin content or using low molecular weight resins to lower the viscosity of the protective liquid solves the problem of excessive viscosity, it introduces new issues such as insufficient viscosity, discontinuous film formation, and inability to uniformly cover the bump.

[0007] Therefore, for the reasons mentioned above, ultrasonic spraying technology is currently mainly used in fields such as photoresist and developer. It has not yet been applied to laser protective liquids for chip packaging, especially for bump chips. Furthermore, there are no reports on the process parameters for this spraying and the requirements for the composition / physicochemical parameters of the protective liquid. This greatly increases the difficulty of applying ultrasonic spraying in the field of laser protective liquids.

[0008] For the reasons mentioned above, developing a laser protective liquid suitable for ultrasonic spraying of bump chips and a method for ultrasonic spraying and laser cutting protection using this protective liquid is of profound significance to the technological development of the semiconductor chip packaging field. Summary of the Invention

[0009] In order to avoid and solve the above-mentioned defects such as contamination by impurities such as silicon slag and oxides, and the inability of the protective liquid viscosity to be suitable for ultrasonic spraying (hereinafter sometimes referred to as "ultrasonic spraying"), as well as the uniformity of film formation, the inventors conducted in-depth research and innovation, and completed the present invention, thus solving the above-mentioned defects.

[0010] More specifically, this invention aims to provide a laser protective liquid for ultrasonic spraying of bump chips and related technical solutions (including its preparation method, its uses, and ultrasonic spraying laser cutting protection methods using it). The laser protective liquid exhibits excellent film-forming properties, capable of forming a uniform and dense protective film layer, and can prevent contamination of the substrate by impurities such as silicon slag and oxides during laser cutting. These significant advantages can substantially improve the processing yield of precision semiconductor components, greatly increase processing efficiency, and significantly reduce production costs.

[0011] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition definition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," etc., and similar meanings.

[0012] The present invention mainly relates to the following specific technical solutions.

[0013] [First technical solution]

[0014] The first technical solution, an object of the present invention, is to provide a laser protective liquid for ultrasonic spraying of bump chips (hereinafter sometimes also referred to as "protective liquid" or "laser protective liquid" or "laser cutting protective liquid", all of which have the same meaning).

[0015] The laser protective solution comprises water-soluble resin, ultraviolet absorber, organic solvent, additives, and ultrapure water.

[0016] More specifically, the laser protective liquid comprises, by weight, the following components:

[0017]

[0018] In the laser protective liquid of the present invention, the water-soluble resin has a mass fraction of 10-20 parts, for example, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts or 20 parts.

[0019] The water-soluble resin is a polyethylene glycol-organic polyacid hyperbranched polyester.

[0020] More specifically, the polyethylene glycol-organic polyacid hyperbranched polyester is prepared according to the following method:

[0021] A1: Add polyethylene glycol and organic polyacids in a molar ratio of 1:1.5-2.5 into a reaction vessel, stir and heat to 150-180℃ to obtain a colorless, transparent, viscous liquid;

[0022] A2: Add p-toluenesulfonic acid as a catalyst to the viscous liquid, stir and react at the same temperature for 6-10 hours, add chloroform, and stir thoroughly to obtain a solution; add diethyl ether to the solution to obtain a precipitate, filter and dry thoroughly to obtain the polyethylene glycol-organic polyacid hyperbranched polyester.

[0023] In step A1 of the preparation method, the organic polyacid is any one or a mixture of any combination of citric acid, oxalic acid, 1,6-adipic acid, succinic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

[0024] In step A1 of the preparation method, the molar ratio of polyethylene glycol to organic polyacid is 1:1.5-2.5, for example, it can be 1:1.5, 1:2 or 1:2.5.

[0025] In step A1 of the preparation method, after adding polyethylene glycol and organic polyacid to the reaction vessel, the mixture is stirred and heated to 150-180°C, for example, 150°C, 160°C, 170°C or 180°C.

[0026] The molecular weight of the polyethylene glycol is 200-600, for example, it can be 200, 300, 400 or 600 (that is, polyethylene glycol 200, PEG-200, polyethylene glycol 300, PEG-300, polyethylene glycol 400, PEG-400 or polyethylene glycol 600, which are known in the art). The most preferred molecular weight is 200 (that is, polyethylene glycol 200, or PEG-200). These polyethylene glycols are very mature and conventional commercial products that can be purchased through various commercial channels, and will not be described in detail here.

[0027] In step A2 of the preparation method, p-toluenesulfonic acid is 0.1-0.3% by mass of the viscous liquid, for example, it can be 0.1%, 0.2% or 0.3%.

[0028] In step A2 of the preparation method, after adding p-toluenesulfonic acid, the reaction is carried out for 6-10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours.

[0029] In step A2 of the preparation method, there is no particular limitation on the amount of chloroform added, as long as it can easily dissolve the reaction product (i.e., the product obtained after 6-10 hours of reaction) and facilitate subsequent ether precipitation. Those skilled in the art can make appropriate selections and determinations for the specific amount, which will not be described in detail here.

[0030] In step A2 of the preparation method, the amount of diethyl ether added is not strictly limited, as long as it facilitates the precipitation. Those skilled in the art can make appropriate selections and determinations for the specific amount, which will not be described in detail here.

[0031] In steps A1-A2 of the preparation method, there are no particular limitations on the stirring, as long as the components are mixed evenly and / or the reaction is favorable. Those skilled in the art can make appropriate selections and determinations according to the actual situation. For example, a stirring speed of 150-300 rpm can usually be selected, which will not be described in detail here.

[0032] The inventors have discovered that the polyester obtained by the above preparation method can guarantee low viscosity and excellent water solubility, making it particularly suitable for ultrasonic atomization spraying. Furthermore, its molecular structure contains a large number of ester groups, exhibiting excellent adhesion and film-forming properties. Under conditions of low resin content (i.e., low dosage) in the laser protective liquid, it can form a uniform, dense, and comprehensive coverage of the wafer and bump surface, avoiding the contamination problem of silicon slag, oxides, and other impurities on the wafer during subsequent laser cutting. This solves a major drawback and technical difficulty in the existing technology.

[0033] In the laser protective liquid of the present invention, the mass fraction of the ultraviolet absorber is 0.2-1 parts, for example, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts or 1 part.

[0034] The ultraviolet absorber is selected from any one or a mixture of any combination of 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, phenyl benzoate, hexamethylphosphoric acid triamine, and resorcinol monobenzoate.

[0035] In the laser protective liquid of the present invention, the organic solvent has a mass fraction of 20-50 parts, for example, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts or 50 parts.

[0036] The organic solvent is selected from any one or a mixture of any of the following: methanol, ethanol, n-propanol, isopropanol, ethylene glycol, ethylene glycol butyl ether (i.e., ethylene glycol monobutyl ether), propylene glycol butyl ether (i.e., propylene glycol monobutyl ether), di-n-butyl ether, methyl tert-butyl ether, acetone, and propylene glycol methyl ether acetate.

[0037] In the laser protective liquid of the present invention, the mass fraction of the additive is 2-4 parts, for example, 2 parts, 2.5 parts, 3 parts, 3.5 parts or 4 parts.

[0038] The additive mentioned above is a vinylpyrrolidone-vinyl acetate copolymer, for example, a vinylpyrrolidone-vinyl acetate copolymer with a molecular weight of 40,000-50,000 and a degree of polymerization of repeating units of 80-100 can be selected. This copolymer is a very common commercial product, and various specifications and grades of this copolymer can be purchased through various commercial channels, and will not be described in detail here.

[0039] The inventors discovered that the additive has the effects of reducing surface tension and improving wettability, which is beneficial to the spreading of atomized droplets on the wafer surface, can promote good contact between the molecules of the wafer and the film layer, further improve the adhesion of the film layer on the wafer, and has a good synergistic effect with polyester.

[0040] In the laser protective solution of the present invention, the mass fraction of ultrapure water is 30-50 parts, for example, 30 parts, 35 parts, 40 parts, 45 parts or 50 parts.

[0041] The ultrapure water is deionized water with a resistance ≥18MΩ.

[0042] As described above, the present invention provides a laser protective liquid for ultrasonic spraying of bump chips. The inventors have discovered that by selecting specific water-soluble resins and specific additives in the laser protective liquid of the present invention, the best technical effects can be achieved (see the subsequent performance test section for details). These effects include excellent film-forming properties, the ability to form a uniform and dense protective film layer, and the ability to avoid contamination of the substrate by impurities such as silicon slag and oxides during laser cutting. The liquid is particularly suitable for ultrasonic spraying of bump chips and subsequent laser processing protection, which can significantly improve the processing qualification rate and yield of precision semiconductor components, and solve current technical problems and difficulties.

[0043] [Second Technical Solution]

[0044] The second technical solution, an objective of the present invention, is to provide a method for preparing the aforementioned laser protective liquid.

[0045] The preparation method includes the following steps:

[0046] B1: Weigh out the required mass proportions of water-soluble resin, ultraviolet absorber, organic solvent, additives, and ultrapure water respectively;

[0047] B2: Add the UV absorber, organic solvent, additives and ultrapure water to a container, stir thoroughly, then add the water-soluble resin and continue stirring until a uniform and transparent solution is obtained, which is the laser protection solution.

[0048] In the preparation method of the present invention, the stirring in step B2 is not particularly limited, as long as the components can be mixed evenly. Those skilled in the art can make appropriate selections and determinations according to the actual situation. For example, a stirring speed of 150-300 rpm can usually be selected, which will not be described in detail here.

[0049] [Third technical solution]

[0050] The third technical solution, an object of the present invention, is to provide the use of the above-mentioned laser protective liquid for ultrasonic spraying treatment of bump chips.

[0051] As described above, the laser protective liquid exhibits excellent film-forming properties, enabling the formation of a uniform and dense protective film layer. Furthermore, it prevents contamination of the substrate by impurities such as silicon slag and oxides during subsequent laser cutting. These significant advantages significantly improve the processing yield and quality of precision semiconductor components, overcoming current technical deficiencies and challenges.

[0052] [Fourth technical solution]

[0053] The fourth technical solution, an objective of this invention, is to provide a method for ultrasonic spraying and laser cutting protection of bump chips using the aforementioned laser protective liquid, the cutting protection method comprising the following steps:

[0054] Step 1: The laser protective liquid is ultrasonically sprayed onto the wafer with bump to obtain a coating layer;

[0055] Step 2: Dry the coating layer into a film to obtain a protective film;

[0056] Step 3: Perform laser cutting to form trenches on the wafer;

[0057] Step 4: Thoroughly clean the wafers cut in Step 3 with ultrapure water to complete the cutting protection treatment.

[0058] In the cutting protection method, the spraying frequency in step 1 is not strictly limited, as long as it is convenient for spraying and adaptable to the speed of the entire production line, for example, 40-50kHz, or even 40kHz, 45kHz or 50kHz.

[0059] In the cutting protection method, in step 1, the distance between the ultrasonic spray nozzle and the wafer is 40-60mm, for example, 40mm, 50mm or 60mm.

[0060] In the cutting protection method, in step 1, the number of spraying times can be 3-6 times, for example, 3 times, 4 times, 5 times or 6 times.

[0061] In the cutting protection method, in step 2, the drying temperature is 50-70℃, for example, it can be 50℃, 60℃ or 70℃.

[0062] In the cutting protection method, in step 3, the power of the laser cutting is 2-8W, for example, it can be 2W, 3W, 4W, 5W, 6W, 7W or 8W.

[0063] In the cutting protection method, in step 4, the ultrapure water is deionized water with a resistance ≥18MΩ.

[0064] In summary, this invention provides several technical solutions, including an ultrasonic spraying protective liquid for laser cutting of bump chips, a preparation method, applications, and a method for protecting bump wafers during cutting using this protective liquid. All of these technical solutions have numerous advantages, such as:

[0065] 1. The protective liquid, by using a specific water-soluble resin, ensures low viscosity and excellent water solubility, making it particularly suitable for ultrasonic atomization spraying. Furthermore, its molecular structure contains a large number of ester groups, exhibiting excellent adhesion and film-forming properties. Under conditions of low resin content (i.e., low dosage), the laser protective liquid can form a uniform, dense, and comprehensive coverage of the wafer and bump surface, avoiding contamination problems caused by impurities such as silicon slag and oxides during subsequent laser cutting. This solves a major drawback and technical difficulty in the current technology.

[0066] 2. The additives used have the functions of reducing surface tension and improving wettability, which are conducive to the spreading of atomized droplets on the wafer surface, can promote good contact between the molecules of the wafer and the film layer, further improve the adhesion of the film layer on the wafer, and have a good synergistic effect with polyester.

[0067] 3. The laser cutting protective liquid of the present invention can be used for ultrasonic spraying. Due to the above-mentioned excellent properties of the protective liquid, it can be applied to ultrasonic spraying, thereby atomizing fine particles with high particle surface activity. Small droplet particles can adhere well to the wafer surface, effectively ensuring uniform film layer and achieving complete coverage of the wafer and bump surface.

[0068] 4. The laser cutting protective fluid is environmentally friendly and pollution-free. After laser grooving is completed, the slag and protective film on the wafer surface can be cleaned with ultrapure water without the need for any organic solvents. It does not cause any damage to the machine or human body, has excellent green production capabilities, and eliminates the generation of waste liquid. Attached Figure Description

[0069] Appendix Figure 1 : is the infrared spectrum of the polyethylene glycol-citric acid hyperbranched polyester obtained in Example 1.

[0070] Appendix Figure 2 (a) is a SEM image of the bump wafer surface after ultrasonic spraying using the laser protective liquid Y1 of Example 1, with a magnification of 50x; (b) is a magnified SEM image of the bump surface, with a magnification of 500x.

[0071] Appendix Figure 3 (a) is a SEM image of the bump wafer surface after ultrasonic spraying with laser protective liquid D3 of Comparative Example 3, with a magnification of 50x; (b) is a magnified SEM image of the bump surface, with a magnification of 500x.

[0072] Appendix Figure 4 (a) is a SEM image of the bump wafer surface after ultrasonic spraying with laser protective liquid D5 (Comparative Example 5), with a magnification of 50x; (b) is a magnified SEM image of the bump surface, with a magnification of 500x.

[0073] Appendix Figure 5 (a) is a SEM image of the bump wafer surface after ultrasonic spraying using laser protective liquid D7 of Comparative Example 7, with a magnification of 50x; (b) is a magnified SEM image of the bump surface, with a magnification of 500x.

[0074] Appendix Figure 6 (a) is a SEM image of the bump wafer surface after ultrasonic spraying with laser protective liquid D9 (Comparative Example 9), with a magnification of 50x; (b) is a magnified SEM image of the bump surface, with a magnification of 500x.

[0075] Appendix Figure 7This is a microscope image magnified 100 times after the bump wafer has been cut and protected using the laser protective liquid Y1 of Example 1.

[0076] Appendix Figure 8 This is a microscope image magnified 50 times of the size of a bump wafer after it has been cut and protected using laser protective liquid D1 (Comparative Example 1).

[0077] Appendix Figure 9 This is a microscope image magnified 50 times after the bump wafer was cut and protected using the laser protective liquid D4 (Comparative Example 4). Detailed Implementation

[0078] The present invention will be described in detail below through specific embodiments. However, the uses and purposes of these exemplary embodiments are only for illustrating the present invention and do not constitute any limitation on the actual protection scope of the present invention, nor are they intended to limit the protection scope of the present invention to these embodiments.

[0079] Unless otherwise specified, the ultrapure water used in any step of the preparation examples, embodiments and / or performance tests below is deionized water with a resistance ≥18MΩ, and therefore will not be listed individually.

[0080] All of the components used below can be purchased through commercial channels, and will not be described in detail here.

[0081] Preparation Example 1: Preparation of Polyethylene Glycol-Citrate Hyperbranched Polyester

[0082] A1: Polyethylene glycol PEG-200 and citric acid were added to a reaction vessel in a 1:2 molar ratio, and the mixture was stirred and heated to 165°C to obtain a colorless, transparent, viscous liquid.

[0083] A2. Add p-toluenesulfonic acid as a catalyst to the viscous liquid, stir at 165°C for 8 hours, add an appropriate amount of chloroform, and stir thoroughly to obtain a solution; add an appropriate amount of diethyl ether to the solution to obtain a precipitate, filter and dry thoroughly to obtain polyethylene glycol-citric acid hyperbranched polyester, which is named J1.

[0084] Of which, by mass, p-toluenesulfonic acid accounts for 0.2% of the viscous liquid.

[0085] The infrared spectrum of the polyethylene glycol-citric acid hyperbranched polyester is shown in the attached image. Figure 1 In the middle, 3400cm -1 and 2860cm -1 The characteristic peaks at 1640 cm⁻¹ are attributed to the stretching vibrations of -OH and -CH₂ in citric acid, respectively. -1 and 1730cm -1The peaks are attributed to the stretching vibrations of the C=C and C=O groups of α,β-unsaturated esters, respectively, while the stretching vibration of the -CO group appears at 1060 cm⁻¹. -1 Therefore, the infrared spectrum confirms the presence of polyethylene glycol-citric acid hyperbranched polyester. Preparation Example 2: Preparation of Polyethylene Glycol-Citrate Hyperbranched Polyester

[0086] A1: Polyethylene glycol PEG-200 and citric acid were added to a reaction vessel at a molar ratio of 1:1.5, and the mixture was stirred and heated to 180°C to obtain a colorless, transparent, viscous liquid.

[0087] A2. Add p-toluenesulfonic acid as a catalyst to the viscous liquid, stir at 180°C for 6 hours, add an appropriate amount of chloroform, and stir thoroughly to obtain a solution; add an appropriate amount of diethyl ether to the solution to obtain a precipitate, filter and dry thoroughly to obtain polyethylene glycol-citric acid hyperbranched polyester, which is named J2. Its infrared spectrum is highly similar to that of the attached [previous product / product]. Figure 1 Therefore, they will not be listed again.

[0088] In steps A1-A2, the stirring speed is 300 rpm. In step A2, p-toluenesulfonic acid accounts for 0.1% of the viscous liquid by mass.

[0089] Preparation Example 3: Preparation of Polyethylene Glycol-Citrate Hyperbranched Polyester

[0090] A1: Polyethylene glycol PEG-200 and citric acid were added to a reaction vessel at a molar ratio of 1:2.5, and the mixture was stirred and heated to 150°C to obtain a colorless, transparent, viscous liquid.

[0091] A2. Add p-toluenesulfonic acid as a catalyst to the viscous liquid, stir at 150°C for 10 hours, add an appropriate amount of chloroform, and stir thoroughly to obtain a solution; add an appropriate amount of diethyl ether to the solution to obtain a precipitate, filter and dry thoroughly to obtain polyethylene glycol-citric acid hyperbranched polyester, named J3, whose infrared spectrum is highly similar to the attached... Figure 1 Therefore, they will not be listed again.

[0092] In steps A1-A2, the stirring speed is 300 rpm. In step A2, the p-toluenesulfonic acid content is 0.3% of the viscous liquid by mass.

[0093] Comparative Preparation Examples 1-3: Preparation of Polyethylene Glycol-Citrate Hyperbranched Polyester

[0094] Except for replacing the polyethylene glycol PEG-200 in Preparation Examples 1-3 with PEG-300, PEG-400 and PEG-600 respectively, all other operations remained unchanged, and the resulting polyethylene glycol-citric acid hyperbranched polyesters were named DJ1, DJ2 and DJ3 in sequence.

[0095] Comparative Preparation Examples 4-9: Preparation of Polyethylene Glycol-Organic Polyacid Hyperbranched Polyester

[0096] Except for replacing citric acid in Preparation Examples 1-3 with oxalic acid (Preparation Example 1), succinic acid (Preparation Example 2), 1,6-adipic acid (Preparation Example 3), isophthalic acid (Preparation Example 1), terephthalic acid (Preparation Example 2), and pyromellitic acid (Preparation Example 3) respectively (where the parentheses indicate the corresponding preparation example), all other operations remained unchanged. The resulting polyethylene glycol-organic polyacid hyperbranched polyesters were named DJ4, DJ5, DJ6, DJ7, DJ8, and DJ9 in sequence.

[0097] Example 1: Preparation of laser protective solution

[0098] B1: Weigh out 15 parts by weight of water-soluble resin J1, 0.6 parts by weight of UV absorber 2,4-dihydroxybenzophenone, 35 parts by weight of organic solvent ethanol, 3 parts by weight of auxiliary agent vinylpyrrolidone-vinyl acetate copolymer (with a molecular weight between 40,000 and 50,000 and a degree of polymerization of repeating units between 80 and 100) and 40 parts by weight of ultrapure water respectively;

[0099] B2: Add the ultraviolet absorber, the organic solvent, the additive and the ultrapure water into a container, stir thoroughly, then add the water-soluble resin, and continue stirring until a uniform and transparent solution is obtained, which is the laser protective solution, named Y1.

[0100] The stirring speed in step B2 is 300 r / min.

[0101] Example 2: Preparation of laser protective solution

[0102] B1: Weigh out 10 parts by weight of water-soluble resin J2, 1 part by weight of ultraviolet absorber 2-hydroxy-4-n-octyloxybenzophenone, 20 parts by weight of organic solvent ethylene glycol butyl ether, 4 parts by weight of auxiliary agent vinylpyrrolidone-vinyl acetate copolymer (with a molecular weight between 40,000 and 50,000 and a degree of polymerization of repeating units between 80 and 100) and 30 parts by weight of ultrapure water respectively;

[0103] B2: Add the ultraviolet absorber, the organic solvent, the additive and the ultrapure water into a container, stir thoroughly, then add the water-soluble resin, and continue stirring until a uniform and transparent solution is obtained, which is the laser protective solution, named Y2.

[0104] The stirring speed in step B2 is 300 r / min.

[0105] Example 3: Preparation of laser protective solution

[0106] B1: Weigh out 20 parts by weight of water-soluble resin J3, 0.2 parts by weight of UV absorber resorcinol monobenzoate, 50 parts by weight of organic solvent acetone, 2 parts by weight of auxiliary agent vinylpyrrolidone-vinyl acetate copolymer (with a molecular weight between 40,000 and 50,000 and a degree of polymerization of repeating units between 80 and 100), and 50 parts by weight of ultrapure water respectively;

[0107] B2: Add the ultraviolet absorber, the organic solvent, the additive and the ultrapure water into a container, stir thoroughly, then add the water-soluble resin, and continue stirring until a uniform and transparent solution is obtained, which is the laser protective solution, named Y3.

[0108] The stirring speed in step B2 is 300 r / min.

[0109] Comparative Examples 1-3: Preparation of Laser Protective Solution

[0110] Except for replacing the water-soluble resins in Examples 1-3 with DJ1, DJ2, and DJ3 respectively, all other operations remained unchanged, and the resulting laser protective solutions were named D1, D2, and D3 sequentially. Comparative Examples 4-9: Preparation of Laser Protective Solutions

[0111] Except for replacing the water-soluble resin in Examples 1-3 with DJ4 (Example 1), DJ5 (Example 2), DJ6 (Example 3), DJ7 (Example 1), DJ8 (Example 2), and DJ9 (Example 3) respectively (where the parentheses indicate the corresponding examples), all other operations remain unchanged, and the resulting laser protective liquids are named D4, D5, D6, D7, D8, and D9 in sequence.

[0112] After obtaining the aforementioned laser protective solutions, the following performance tests were conducted, as detailed below.

[0113] Bump chip ultrasonic spraying laser cutting protection test

[0114] The ultrasonic spraying and laser cutting protection test for the bump chip (i.e., the I-II test below) includes the following steps:

[0115] Step 1: Apply laser protective liquid to the bumped wafer using ultrasonic spraying at a frequency of 45kHz to obtain a coating layer;

[0116] In the ultrasonic spraying process, the distance between the nozzle and the wafer is 50mm, and the spraying is performed 4 times.

[0117] Step 2: Dry the coating layer at 60°C to form a film, thus obtaining a protective film;

[0118] Step 3: Perform laser cutting at a power of 5W to form trenches on the wafer;

[0119] Step 4: fully cleaning the wafer diced in Step 3 with ultrapure water, so as to complete the dicing protection treatment.

[0120] I. Wafer and bump protection performance testing

[0121] After implementing the above steps 1 to 2 with different laser protective solutions, the properties of the obtained protective films are shown in the following drawings, specifically as follows:

[0122] 1. Dra Figure 2 wing: (a) is an SEM image of the surface of a bump wafer after ultrasonic spraying with the laser protective solution Y1 of Example 1, with a magnification of 50 times; (b) is an enlarged SEM image of the bump surface therein, with a magnification of 500 times.

[0123] It can be seen that the obtained protective film is uniform and smooth, and completely covers the entire wafer surface and the entire bump surface, thereby providing very excellent subsequent dicing protection for the wafer surface and the bump surface.

[0124] When the laser protective solutions Y2 to Y3 are used, the morphology and protection performance of the protective film are exactly the same as those of Dra Figure 2 wing, and similarly the obtained protective film is uniform and smooth, and completely covers the entire wafer surface and the entire bump surface, thereby providing very excellent subsequent dicing protection for the wafer surface and the bump surface, which will not be listed one by one.

[0125] 2. Dra Figure 3 wing: (a) is an SEM image of the surface of a bump wafer after ultrasonic spraying with the laser protective solution D3 of Comparative Example 3, with a magnification of 50 times; (b) is an enlarged SEM image of the bump surface therein, with a magnification of 500 times.

[0126] It can be seen that the overall obtained protective film is uniform and smooth, and completely covers the wafer surface, but cannot completely cover the bumps. Although the covered portion of the bumps is uniform and smooth, a plurality of bumps have exposed areas (see the plurality of bumps in the upper right and lower right portions of (a)), and it can be further clearly seen from (b) that complete coverage of the bumps is not achieved, and obvious exposed areas exist.

[0127] When the laser protective solutions D1 to D2 are used, the morphology and protection performance of the protective film are highly similar to those of Dra Figure 3 wing, that is, they also uniformly and smoothly cover the wafer surface completely. Although they still cannot completely cover the bumps, the relationship of the area of the exposed areas is D1<D2<D3, that is, as the molecular weight of PEG increases, the area of the exposed areas increases. Since the overall coverage is highly similar, it will not be listed one by one here.

[0128] Therefore, it is evident that the molecular weight of PEG can significantly affect its protective performance. The inventors believe this is because the molecular weight influences the viscosity and spatial molecular structure of the resulting polyester. When using PEG-200, on the one hand, the viscosity of the resulting laser protective liquid is optimal, facilitating spraying; on the other hand, the suitable spatial shape of the molecular structure, such as appropriate overall molecular length and resistance to entanglement into a three-dimensional network structure, results in uniform film formation and excellent film-forming effect. However, when using high molecular weight PEG, not only does the viscosity of the laser protective liquid increase, reducing film uniformity, but the increased molecular length also makes it easier for the molecules to entangle and form a three-dimensional network structure, making it more difficult to achieve uniform film formation on the raised spherical bump.

[0129] Therefore, the optimal PEG is PEG-200.

[0130] 3. Appendix Figure 4 (a) is a SEM image of the bump wafer surface after ultrasonic spraying with laser protective liquid D5 (Comparative Example 5), with a magnification of 200x; (b) is a magnified SEM image of the bump surface.

[0131] When using laser protective solutions D4 and D6, the protective film morphology and protective condition are highly similar to those of the attached [product / service]. Figure 4 Therefore, they will not be listed one by one.

[0132] 4. Appendix Figure 5 (a) is a SEM image of the bump wafer surface after ultrasonic spraying using laser protective liquid D7 of Comparative Example 7, with a magnification of 50x; (b) is a magnified SEM image of the bump surface, with a magnification of 500x.

[0133] When using laser protective fluid D8, the protective film morphology and protective condition are highly similar to those of the attached... Figure 5 Therefore, they will not be listed again.

[0134] 5. Appendix Figure 6 (a) is a SEM image of the bump wafer surface after ultrasonic spraying with laser protective liquid D9 (Comparative Example 9), with a magnification of 50x; (b) is a magnified SEM image of the bump surface, with a magnification of 500x.

[0135] From the appendix Figure 4-6 It is evident that altering the organic polyacids in the solution significantly degrades the film-forming properties of the resulting laser protective solution: it fails to form a uniform and smooth protective film, resulting in uneven and inconsistent thicknesses on the wafer surface; furthermore, it cannot completely cover the bump, leaving large exposed areas, and even when covered, the coverage is merely blocky or sheet-like, rendering it unsuitable for practical applications.

[0136] The inventors believe this is because citric acid contains both hydroxyl and carboxyl groups in its structure. The carboxyl group forms an ester group with PEG, while the hydroxyl group can enhance the interaction between the film and the substrate through hydrogen bonding. Furthermore, due to its suitable carbon chain length, it is easier to form a dense protective layer on the substrate.

[0137] In summary, citric acid is the most preferred organic polyacid in this invention.

[0138] II. Cutting Protection Performance Test

[0139] After performing steps 1-4 above using different laser protective solutions, the cutting protection performance of the resulting protective film is shown in the following figures, as detailed below:

[0140] 1. Appendix Figure 7 This is a microscope image magnified 100 times after the bump wafer has been cut and protected using the laser protective liquid Y1 of Example 1.

[0141] This demonstrates that even under 100x magnification, there is no silicon slag or oxide contaminant on the wafer surface, indicating a very high level of overall cleanliness. The area around the dicing groove (the straight groove in the middle) is also very clean, free of any silicon slag or oxide contaminant.

[0142] The microscope images after cutting protection treatment with laser protective fluid Y2-Y3 are exactly the same as those in the attached image. Figure 7 Similarly, there is no silicon slag or oxide contaminants on the wafer surface, and the overall cleanliness is very high. The area around the dicing groove (i.e., the straight groove in the middle) is also very clean, with no silicon slag or oxide contaminants, so they will not be listed individually.

[0143] 2. Appendix Figure 8 This is a microscope image magnified 50 times of the size of a bump wafer after it has been cut and protected using laser protective liquid D1 (Comparative Example 1).

[0144] Compared to using Y1 to magnify 100 times, when using D1 to magnify 50 times, as shown in the two white ellipses in the figure, it is clear that there is a lot of obvious silicon slag around the cutting path.

[0145] The microscope image after cutting protection treatment using laser protective fluid D2-D3 is similar in height to the attached image. Figure 8 This refers to the presence of silicon slag and dirt around the cutting path, which will not be listed individually due to their similar overall height.

[0146] 3. Appendix Figure 9 This is a microscope image magnified 50 times after the bump wafer was cut and protected using the laser protective liquid D4 (Comparative Example 4).

[0147] Compared to using Y1 with 100x magnification, when using D4 with 50x magnification, as shown in the six white ellipses in the figure, it is clear that there are some contaminants such as silicon slag and oxides on the wafer surface. At the same time, it is clear that there is more severe silicon slag contamination around the dicing track. The quantity and severity are significantly worse than when using D1-D3.

[0148] The microscope image after cutting protection treatment using laser protective fluid D5-D9 is similar in height to the attached image. Figure 9 This means that there is more silicon slag and oxides on the wafer surface and around the dicing track, especially severe silicon slag contamination around the dicing track. Due to the overall similarity, they will not be listed one by one.

[0149] In summary, this invention provides a laser protective liquid for ultrasonic spraying of bump chips and its related technical solutions (including its preparation method, its uses, and ultrasonic spraying laser cutting protection methods using it). The laser protective liquid exhibits excellent film-forming properties, capable of forming a uniform and dense protective film layer, providing excellent comprehensive and dense coverage protection for the wafer surface and bump, and preventing contamination from silicon slag, oxides, and other impurities during laser cutting. These significant advantages can substantially improve the yield rate of precision semiconductor components, greatly increase processing efficiency, and significantly reduce production costs.

[0150] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention. Furthermore, it should be understood that after reading the technical description of this invention, those skilled in the art can make various alterations, modifications, and / or variations to the invention, and all such equivalent forms also fall within the scope of protection defined by the appended claims.

Claims

1. A laser protective liquid for ultrasonic spraying of bump chips, wherein the laser protective liquid comprises, by weight, the following components: 10-20 parts of water-soluble resin; 0.2-1 part of ultraviolet absorber; Organic solvent 20-50 parts; 2-4 parts of auxiliary agent; 30-50 parts ultrapure water; The water-soluble resin is polyethylene glycol-organic polyacid hyperbranched polyester; The polyethylene glycol-organic polyacid hyperbranched polyester is prepared according to the following method: A1: Add polyethylene glycol and organic polyacids in a molar ratio of 1:1.5-2.5 into a reaction vessel, stir and heat to 150-180℃ to obtain a colorless, transparent, viscous liquid; A2: Add p-toluenesulfonic acid as a catalyst to the viscous liquid, stir and react at the same temperature for 6-10 hours, add chloroform, and stir thoroughly to obtain a solution; add diethyl ether to the solution to obtain a precipitate, filter and dry thoroughly to obtain the polyethylene glycol-organic polyacid hyperbranched polyester.

2. The laser protective liquid as described in claim 1, characterized in that: In step A2, p-toluenesulfonic acid is 0.1-0.3% of the viscous liquid by mass.

3. The method for preparing the laser protective liquid according to claim 1 or 2, characterized in that: The preparation method includes the following steps: B1: Weigh out the required mass proportions of water-soluble resin, ultraviolet absorber, organic solvent, additives, and ultrapure water respectively; B2: Add the UV absorber, organic solvent, additives and ultrapure water to a container, stir thoroughly, then add the water-soluble resin and continue stirring until a uniform and transparent solution is obtained, which is the laser protection solution.

4. The use of the laser protective liquid according to claim 1 or 2 for ultrasonic spraying treatment of bump chips.

5. A method for ultrasonically spraying laser cutting protection of bump chips using the laser protective liquid according to claim 1 or 2, the cutting protection method comprising the following steps: Step 1: The laser protective liquid is ultrasonically sprayed onto the wafer with bump to obtain a coating layer; Step 2: Dry the coating layer into a film to obtain a protective film; Step 3: Perform laser cutting to form trenches on the wafer; Step 4: Thoroughly clean the wafer cut in Step 3 with ultrapure water to complete the cutting protection treatment.

6. The cutting protection method as described in claim 5, characterized in that: In step 1, the spraying operation frequency is 40-50kHz.

7. The cutting protection method as described in claim 5 or 6, characterized in that: In step 1, the distance between the ultrasonic spray nozzle and the wafer is 40-60 mm.

8. The cutting protection method as described in claim 7, characterized in that: In step 3, the power of the laser cutting is 2-8 W.

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