Protective liquid for whole wafer thinning and cutting process and preparation method and application thereof

Abstract

The invention relates to a protection liquid for a wafer thinning and cutting whole process and a preparation method and application thereof. The protection liquid comprises a curing agent, water-soluble resin and deionized water; the mass part ratio of the curing agent to the water-soluble resin to the deionized water is (5-10): (10-50): (40-100). Wherein the curing agent has a special structure, so that the adhesive force, the water resistance and the pencil hardness of the resin can be comprehensively improved, thereby ensuring that a film layer is always firmly attached to the surface of a chip in a plurality of processes from wafer thinning to wafer cutting, and chip damage caused by chip sputtering and a clamp can be resisted. The protective liquid containing the curing agent can be coated on the surface of a wafer from the beginning of a wafer thinning process until the cutting of a blade is finished, the protective liquid covers more processes, and the protection on the wafer is more comprehensive.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor manufacturing technology, and in particular relates to a protective liquid used in the entire process of wafer thinning and cutting, and a preparation method and application thereof. Background Art

[0002] The basic process of chip packaging includes wafer thinning, wafer filming, wafer cutting, chip pasting and wire bonding. Wafer thinning is to grind the back of the wafer with a diamond grinding wheel. Before thinning, a film will be pasted on the chip device layer to prevent the circuit from being damaged. After three steps of rough grinding, fine grinding and polishing, the wafer is thinned to the required thickness. There are two main problems commonly encountered in the wafer thinning process. One is the warping caused by the introduction of mechanical stress, and the other is that the grinding process is accompanied by the generation of a large amount of heat, and the heat damage caused by untimely heat dissipation.

[0003] The most common method for cutting ultra-thin chips is diamond cutting blades, which separates chips by continuously shedding diamond abrasives to update the cutting surface. Silicon is a brittle material with high hardness and low melting point. Diamond abrasives will introduce greater stress when cutting silicon wafers. The most common problem is edge collapse, including metal layer edge collapse and back collapse. In addition, when cutting ultra-thin wafers, particles will be generated at the cut, and these particles are easily lifted and fall onto the ultra-thin wafers. At the same time, during the transfer process of the cut ultra-thin wafers, many particles in the environment will fall on the surface of the ultra-thin wafers. Many high-end ultra-thin wafers are highly sensitive to particles, so their qualified rate will be greatly reduced. At the same time, water will be sprayed on the blade and the ultra-thin wafer cutting point to cool down during the cutting process. The high-speed rotating blade wheel will generate a water flow with a certain impact force and carrying cutting debris, which will splash onto the surface of the ultra-thin wafer and cause scratches, resulting in a decrease in the qualified rate of the wafer.

[0004] In the entire process of ultra-thin wafers from wafer thinning to wafer cutting, it is very important to prevent the particles generated by the environment and cutting from falling onto the surface of the ultra-thin wafer, the debris generated during cutting from scratching the surface of the ultra-thin wafer, and the warping or edge collapse caused by grinding and cutting, which will cause the ultra-thin wafer qualification rate to drop. Therefore, it is urgent to develop a protective liquid and protection method for the entire process of ultra-thin wafers from wafer thinning to the end of cutting to protect the delicate structure on the wafer surface from damage. Summary of the invention

[0005] The technical problem solved by the present invention is: how to avoid the problem of particles generated by the environment and cutting falling onto the surface of the ultra-thin wafer, debris scratching the surface of the ultra-thin wafer, warping or edge collapse caused by grinding and cutting, etc. during the entire process from wafer thinning to wafer cutting of an ultra-thin wafer with a thickness not exceeding 100 microns.

[0006] In view of the technical problems existing in the prior art, the present invention designs a protective liquid for the whole process of wafer thinning and cutting, its preparation method and application, which protects the ultra-thin wafer throughout the whole process from grinding to cutting end, avoiding damage to the precise structures on the surface of the ultra-thin wafer, so as to improve the qualified rate of the ultra-thin wafer.

[0007] It should be noted that in the present invention, unless otherwise specified, the specific meaning of "including" involving component limitations and descriptions includes both the open "including", "containing" and their similar meanings, and also the closed "consisting of..." and their similar meanings.

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

[0009] [The first technical solution]

[0010] In a first aspect, a technical solution of the present invention lies in providing a curing agent. In the present invention, the curing agent is a waterborne isocyanate curing agent, and the curing agent is a compound of formula 1: Wherein, R 1 , R 2 , R 3 is a substituted or unsubstituted alkyl group with 10 or less carbon atoms or a substituted or unsubstituted aryl group; R 4 , R 5 is a substituted or unsubstituted alkyl group with 10 or less carbon atoms, a substituted or unsubstituted aryl group or hydrogen; m and n are integers from 1 to 12, and can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.

[0011] Furthermore, the aryl group is any one of phenyl, biphenyl, naphthyl, anthryl, phenanthryl, fluorenyl.

[0012] Furthermore, R 1 , R 2 , R 3 are substituted or unsubstituted alkyl groups with 1 to 6 carbon atoms, substituted or unsubstituted aryl groups; R 4 , R 5 are substituted or unsubstituted alkyl groups with 1 to 6 carbon atoms, substituted or unsubstituted aryl groups or hydrogen; n is an integer from 6 to 10, and m is an integer from 6 to 10.

[0013] Furthermore, R 1 is any one of -(CH 2 ) x1 -, among others, Among them, x1, y, and z are integers from 2 to 10, and can be, for example, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0014] Further, x1 is 4 or 6, y is 1, and z is 1.

[0015] Further, R 2 is -(CH 2 ) x2 -; x2 is an integer from 1 to 10, and can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0016] Further, x2 is an integer from 1 to 4.

[0017] Further, R 3 is -(CH 2 ) x3 -; x3 is an integer from 1 to 10, and can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0018] Further, x3 is an integer from 1 to 3.

[0019] Further, R 4 is -(CH 2 ) x4 CH 3 ; x4 is an integer from 0 to 9, and can be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9.

[0020] Further, x4 is 0 or 1.

[0021] Further, R 5 is H, phenyl, -(CH 2 ) x5 CH 3 , -CH-(CH 3 ) 2 any one of them, and x5 is an integer from 0 to 9, and can be, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9.

[0022] The curing agent of formula 1 provided by a technical solution of the present invention is a product obtained by reacting a triol, a diisocyanate, product A, and an imidazole compound; The said product A is a product obtained by reacting polyethylene glycol - polylysine and an amino - type silane coupling agent.

[0023] [Second technical solution]

[0024] Secondly, a technical solution of the present invention lies in providing a preparation method of the curing agent of formula 1, including the following steps:

[0025] Step 1: Under the condition of nitrogen protection at 100 - 120°C, add polyethylene glycol - polylysine and an amino - silane coupling agent to a reactor. After stirring for 2 - 4 h, product A is obtained;

[0026] Step 2: Add a trihydric alcohol and a diisocyanate to the reactor, heat up to 60 - 80°C, and react for 3 - 4 h under the condition of nitrogen protection. Then add product A prepared in Step 1 and continue to react at 60 - 80°C for 1 - 2 h to obtain product B;

[0027] Step 3: Add an imidazole - based compound to product B and react at 80 - 100°C for 2 - 3 h to obtain the curing agent shown in Formula 1.

[0028] Furthermore, the amino - silane coupling agent is any one of (3 - aminopropyl)triethoxysilane and (3 - aminopropyl)trimethoxysilane.

[0029] Furthermore, the trihydric alcohol is any one of 1,2,3 - propanetriol, 1,2,4 - butanetriol, and 1,2,6 - hexanetriol.

[0030] Furthermore, the diisocyanate is any one of hexamethylene diisocyanate, 1,3 - diisocyanatobenzene, isophorone diisocyanate, 2,6 - tolylene diisocyanate, p - phenylene diisocyanate, m - xylylene diisocyanate, and 1,4 - butanediisocyanate.

[0031] Furthermore, the imidazole - based compound is any one of imidazole, 2 - phenylimidazole, 2 - methylimidazole, 2 - ethylimidazole, and 2 - isopropylimidazole.

[0032] Furthermore, the molar ratio of polyethylene glycol - polylysine to the amino - silane coupling agent is 1 - 1.5:1.

[0033] Furthermore, the molar ratio of the trihydric alcohol to the diisocyanate is 1:3.5 - 4.

[0034] Furthermore, the molar ratio of the trihydric alcohol to the amino - silane coupling agent is 1.72 - 1:1.

[0035] Furthermore, the molar ratio of imidazole to the trihydric alcohol is 1 - 3:1.

[0036] [The third technical solution]

[0037] In a third aspect, a technical solution of the present invention is to provide a protective liquid for the whole process of wafer thinning and cutting, and the components include a curing agent, a water - soluble resin, and deionized water; the mass ratio of the curing agent, the water - soluble resin, and deionized water is 5 - 10:10 - 50:40 - 100.

[0038] Furthermore, the structural formula of the curing agent is Formula 1.

[0039] Furthermore, the water-soluble resin is a hydroxyl-containing acrylic resin with a molecular weight of 5000 - 20000.

[0040] Furthermore, the water-soluble resin is one or more of hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxyethyl methacrylate - acrylic acid copolymer, methyl methacrylate - hydroxyethyl methacrylate copolymer, butyl acrylate - hydroxyethyl acrylate copolymer, and methyl methacrylate - hydroxyethyl acrylate - acrylic acid copolymer.

[0041] Furthermore, the water-soluble resin is one or more of hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxyethyl methacrylate - acrylic acid copolymer, and methyl methacrylate - hydroxyethyl methacrylate copolymer.

[0042] [Fourth Technical Solution]

[0043] Fourthly, a technical solution of the present invention lies in providing a preparation method of the above protective liquid, comprising the following steps:

[0044] Step 1: Weigh the curing agent, water-soluble resin, and deionized water in their respective parts by mass.

[0045] Step 2: Stir the respective components at a speed of 200 - 500 r / min at room temperature for 1 - 5 h to obtain the protective liquid.

[0046] Furthermore, the stirring speed in Step 2 is 200 - 500 r / min, for example, it can be 200 r / min, 300 r / min, 400 r / min, or 500 r / min.

[0047] Furthermore, the stirring time in Step 2 is 1 - 5 h, for example, it can be 1 h, 2 h, 3 h, 4 h, or 5 h.

[0048] [Fifth Technical Solution]

[0049] Fifthly, a technical solution of the present invention lies in providing the use of the protective liquid in protecting the precise structure on the surface of the chip during the multi-process from wafer thinning to chip cutting.

[0050] [Sixth Technical Solution]

[0051] Sixthly, a technical solution of the present invention lies in providing a usage method of the protective liquid, including the following steps:

[0052] Step 1: Drop the protective liquid onto the surface of the wafer and rotate it at a speed of 500 - 1500 r / min for 30 - 60 s.

[0053] Step 2: Bake the wafer with the protective liquid spin-coated on its surface at 100 - 130 °C for 5 - 30 min to cure and form a film to form a protective layer; the protective layer is formed on the front precision structure of the wafer;

[0054] Step 3: Stick a tape on one side of the wafer covered with the protective layer, and the adhered tape is located on the front of the wafer; grind, polish, and thin the back of the wafer to the required thickness; remove the grinding tape;

[0055] Step 4: Stick a layer of blue film on the back of the wafer and cut the wafer;

[0056] Step 5: After screening and rearranging the obtained chips, clean the protective layer on the surface of the chips to remove the protective layer.

[0057] The curing agent of the present invention has unique advantages:

[0058] First, in the present invention, the protective liquid is coated on the surface of the wafer and heated and cured before the wafer thinning process. Under the heating condition, the curing agent in the protective liquid releases free isocyanate groups, which further react with the hydroxyl groups in the water-soluble resin, increasing the crosslinking density of the system.

[0059] Second, the hydrolysis of the siloxane in the curing agent can form Si - O - Si covalent bonds with the silicon substrate, enhancing the adhesion between the film layer and the wafer. At the same time, during the curing process, silicon atoms migrate to the surface of the film, improving the hydrophobicity of the film layer. The increase in the crosslinking density of the system makes the film layer structure more dense, further preventing the penetration of water molecules and improving the water resistance of the film.

[0060] Third, the introduction of rigid structures such as aryl groups and isocyanate groups in the curing agent also improves the pencil hardness of the film layer.

[0061] Fourth, the amino groups in the curing agent and the hydroxyl groups in the water-soluble resin form a hydrogen bond network, which can direct the reactants to approach, reduce the energy of the transition state, and accelerate the curing reaction process, so that the curing agent and the water-soluble resin can react fully in a short time.

[0062] Therefore, the curing agent with a special structure comprehensively improves the adhesion, water resistance, and pencil hardness of the water-soluble resin, ensuring that the film layer firmly adheres to the surface of the wafer throughout the processes from wafer thinning to wafer cutting, and can resist wafer damage caused by chip sputtering, etc.

[0063] The present invention provides a protective liquid for the whole process of wafer thinning and cutting, its preparation method and application, and has the following beneficial effects:

[0064] 1. The protective liquid of the present invention is coated on the surface of the wafer starting from the wafer thinning process until the cutting is completed. The protective liquid covers more processes and provides more comprehensive protection for the wafer.

[0065] 2. The protective liquid coating of the present invention has excellent adhesion, water resistance, and hardness. During the baking process, the isocyanate groups in the curing agent are released and react with the hydroxyl groups in the water-soluble resin, increasing the cross-linking degree of the water-soluble resin. In addition, the aryl, urethane, and siloxane groups introduced by the curing agent endow the film layer with higher water resistance, hardness, and adhesion. This can ensure that the coating adheres firmly to the wafer surface during grinding to cutting, protecting the precise structures on the wafer from being contaminated or damaged.

[0066] 3. The protective liquid of the present invention has excellent storage stability. Since the isocyanate groups have been blocked with imidazole compounds, the isocyanate groups will only be released when heated to the deblocking temperature. At room temperature, there are no free isocyanate groups in the protective liquid, and it will not react with water, so the protective liquid can be stored stably.

[0067] Therefore, the protective liquid and protection method of the present invention have very good application prospects and potential for large-scale industrial promotion in the field of ultra-thin wafer processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 : Infrared spectrum diagram of curing agent 1;

[0069] Figure 2 : Microscopic photograph of the electrode after soaking and cleaning in Comparative Example 2, magnified 1870 times;

[0070] Figure 3 : Microscopic photograph of the electrode after soaking and cleaning in Example 1, magnified 1870 times;

[0071] Figure 4 : Photograph of the film layer state after the water resistance test in Comparative Example 1;

[0072] Figure 5 : Photograph of the film layer state after the water resistance test in Example 1;

[0073] Figure 6 : Photograph after the adhesion test in Comparative Example 4;

[0074] Figure 7 : Photograph after the adhesion test in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0075] The following further describes the present invention in conjunction with specific examples and the accompanying drawings:

[0076] Preparation methods of curing agent 1 - curing agent 8:

[0077] Step 1: Under the condition of nitrogen protection at 120°C, add the polymer and the amino silane coupling agent into the reactor. After stirring for 3 hours, product A is obtained;

[0078] Step 2: Add the triol and the diisocyanate into the reactor, heat up to 80°C, and react for 4 hours under the condition of nitrogen protection. Then add product A prepared in Step 1, and continue to react at 80°C for 2 hours to obtain product B;

[0079] Step 3: Add the imidazole compound into product B and react at 100°C for 3 hours to obtain the curing agent shown in Formula 1.

[0080] Table 1: Curing Agents 1 - 8

[0081] Preparation methods of the protection liquid examples and comparative examples of the present invention:

[0082] Step 1: Weigh the curing agent, water-soluble resin, and deionized water in their respective parts by mass;

[0083] Step 2: Add each component into a mixing container equipped with a stirrer, and stir at a speed of 400 r / min at room temperature for 2 hours to obtain the protection liquid.

[0084] Table 2: Examples 1 - 9 of the protection liquid

[0085] Table 3: Comparative Examples 1 - 5 of the protection liquid

[0086] Table 4: Test data of Examples 1 - 9 and Comparative Examples 1 - 5

[0087] Regarding performance testing and description:

[0088] Usage methods of the protection liquid examples and comparative examples of the present invention:

[0089] Step 1: Drop 50 ml of the protection liquid onto the surface of the wafer, and use a spin coater to rotate at a speed of 1000 r / min for 60 s;

[0090] Step 2: Transfer the wafer with the protection liquid spin-coated on its surface to a forced air drying oven, and bake at 120°C for 10 min to cure into a film to form a protective layer; the protective layer is formed on the precise structure on the front side of this wafer;

[0091] Step 3: Attach tape to one side of the wafer covered with the protective layer, with the adhesive tape located on the front side of the wafer; grind, polish, and thin the back side of the wafer to the required thickness; remove the grinding tape;

[0092] Step 4: Stick a layer of blue film on the back of the wafer and cut the wafer;

[0093] Step 5: After screening and rearranging the cut chips, clean the protective layer on the surface of the chips and remove the protective layer.

[0094] Performance 1 The test method for aluminum electrode corrosion is:

[0095] The chip was immersed in the protective solution for 6 h in a static Class 100 clean room, then taken out and the chip surface was rinsed with ultrapure water for 2 min and dried with nitrogen. The corrosion of the electrode was observed under a dark field microscope at a magnification of 1870 times.

[0096] Performance 2 Water resistance test method is:

[0097] Spin-coat the protective liquid on the Dummy sheet and solidify it, soak it in water, take it out after 24 hours and spin-dry it, and observe the state of the film layer. If the protective film on the Dummy sheet does not fall off, it indicates that its water resistance can meet the requirements.

[0098] Performance 3 pencil hardness test method is:

[0099] The protective liquid was spin-coated on the dummy sheet and cured. The hardness of the paint film was measured using a portable pencil hardness tester (Zhonghua brand high-grade drawing pencil) according to GB / T 6739-2006. The hardness from soft to hard is: 9B-8B-7B-6B-5B-4B-3B-2B-1B-HB-FH-1H-2H-3H-4H-5H-6H-7H-8H-9H.

[0100] Performance 4 Adhesion test method is:

[0101] The protective liquid is spin-coated on the dummy sheet and cured, and the adhesion is tested by the Hundred Grid Method. Adhesion level judgment standard: 0B: There are flakes of coating falling off at the edge and intersection of the scribe line, and the total area of ​​​​falling off is greater than 65%; 1B: There are flakes of coating falling off at the edge and intersection of the scribe line, and the total area of ​​​​falling off is between 35-65%; 2B: There are flakes of coating falling off at the edge and intersection of the scribe line, and the total area of ​​​​falling off is between 15-35%; 3B: There are small flakes of coating falling off at the edge and intersection of the scribe line, and the total area of ​​​​falling off is between 5-15%; 4B: There are small flakes of coating falling off at the intersection of the scribe line, and the total area of ​​​​falling off is less than 5%; 5B: The edge of the scribe line is smooth, and there is no coating falling off at the edge and intersection of the scribe line.

[0102] Performance 5 Storage stability test method is:

[0103] Store the protective liquid at 25°C, observe its appearance and state every half a month, and test its viscosity. If the appearance, state, and viscosity of the protective liquid do not change, it is considered to be stable during storage, and then determine the maximum time the protective liquid can be stably stored, and record the time when the protective liquid gels. If the curing agent releases isocyanate, the protective liquid will gel; if the appearance and viscosity of the protective liquid do not change, there is no free isocyanate.

[0104] Analysis of the test results:

[0105] Based on Table 4, it can be seen that the protection liquid of the embodiment of the present invention significantly improves water resistance, adhesion, pencil hardness and storage time, and reduces corrosion of the aluminum electrode compared with the protection liquid of the comparative example.

[0106] Comparative Example 1 does not contain a curing agent, and the protective liquid only contains a water-based resin. The adhesion and water resistance on the substrate are very poor, and the absence of a rigid group also makes the pencil hardness of the film layer low.

[0107] The curing agent of Comparative Example 2 is Product B. The silane coupling agent in Product B can enhance the adhesion between the resin and the substrate, but the enhancement is small.

[0108] The curing agent of Comparative Example 3 is product A, i.e., an unblocked isocyanate curing agent. Although the film performance is significantly improved, the protective liquid contains free isocyanate groups, which react with water and resin. The protective liquid cannot be stored stably and quickly gels after being placed for one day, making it unusable subsequently.

[0109] The curing agent of Comparative Example 4 is toluene diisocyanate, which can increase the crosslinking density of the resin, but compared with the isocyanate curing agent containing a silane coupling agent in the embodiment, the improvement of the adhesion between the film layer and the substrate is smaller.

[0110] The curing agent of Comparative Example 5 is curing agent 8, which does not contain free amino groups and cannot direct the reactants to approach and accelerate the curing reaction process. Therefore, the resin and the curing agent cannot fully react in a short time. Therefore, the film performance is slightly improved, but still worse than the embodiment.

[0111] Further comparison is made through the attached drawings in the specification:

[0112] from Figure 1 It can be seen that 3336cm -1 The NH stretching vibration peak is at 1727 cm -1 The peak of C=O stretching vibration is at 1040cm -1 . At 2260cm -1No characteristic peak of the -N=C=O group was observed at this position, indicating that the isocyanate groups were completely reacted. Thus, it can be proved that the blocked curing agent 1 was successfully synthesized. From Figure 2 It can be seen that after soaking and cleaning in Comparative Example 2, a blue bright structure appeared on the surface of the chip electrode under the dark field of the microscope, indicating that the surface of the chip electrode was severely corroded. From Figure 3 It can be seen that after soaking and cleaning in Example 1, there were almost no irregular bright structures on the surface of the chip electrode under the dark field of the microscope, indicating that the surface of the chip electrode was not corroded. From Figure 4 It can be seen that after the water resistance test in Comparative Example 1, all the film layers peeled off, indicating that the water resistance of the film layer was poor. From Figure 5 It can be seen that after the water resistance test in Example 1, the film layer remained intact without any change, indicating that the water resistance of the film layer was good. From Figure 6 It can be seen that after the adhesion test in Comparative Example 4, the area of the film layer peeled off after the 3M tape was torn off exceeded 5% but was less than 15%, and the adhesion grade was judged to be 3B. From Figure 7 It can be seen that after the adhesion test in Example 1, the film layer remained intact without any peeling off after the 3M tape was torn off, and the adhesion grade was judged to be 5B.

[0113] The present invention has been described exemplarily above in combination with the embodiments and the drawings. Obviously, the implementation of the present invention is not limited by the above-mentioned methods. As long as various improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A curing agent, characterized in that The curing agent is a compound of the following formula 1: Wherein, R1, R2, and R3 are substituted or unsubstituted alkyl groups having 10 or less carbon atoms or substituted or unsubstituted aryl groups; R4 and R5 are substituted or unsubstituted alkyl having 10 or less carbon atoms, substituted or unsubstituted aryl or hydrogen; m and n are integers of 1-12.

2. A method for preparing the curing agent according to claim 1, characterized in that: The steps include: Step 1: Add polyethylene glycol-polylysine and amino silane coupling agent into a reactor at 100-120° C. under nitrogen protection, and stir for 2-4 hours to obtain product A; Step 2: Add triol and diisocyanate to the reactor, raise the temperature to 60-80°C, react for 3-4 hours under nitrogen protection, add product A obtained in step 1, keep the temperature at 60-80°C and continue to react for 1-2 hours to obtain product B; Step 3: Add an imidazole compound to product B, react at 0-100° C. for 2-3 hours to obtain a curing agent as shown in Formula 1.

3. The method for preparing a curing agent according to claim 2, characterized in that: The amino silane coupling agent is any one of (3-aminopropyl)triethoxysilane and (3-aminopropyl)trimethoxysilane; and / or the triol is any one of 1,2,3-propanetriol, 1,2,4-butanetriol and 1,2,6-hexanetriol; and / or the diisocyanate is any one of hexamethylene diisocyanate, 1,3-diisophenyl cyanate, isophorone diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, m-phenylenediisocyanate and 1,4-butyl diisocyanate; and / or the imidazole compound is any one of imidazole, 2-phenylimidazole, 2-methylimidazole, 2-ethylimidazole and 2-isopropylimidazole.

4. The method for preparing a curing agent according to claim 2, characterized in that: The molar ratio of the polyethylene glycol-polylysine to the amino silane coupling agent is 1-1.5:1; the molar ratio of the triol to the diisocyanate is 1:3.5-4; and the molar ratio of the imidazole to the triol is 1-3:

1.

5. A protective liquid for the whole process of wafer thinning and cutting, characterized in that: Contains the curing agent according to claim 1.

6. The protective liquid according to claim 5, characterized in that: The components include a curing agent, a water-soluble resin and deionized water; the mass ratio of the curing agent, the water-soluble resin and the deionized water is 5-10:10-50:40-100.

7. The protective liquid according to claim 6, characterized in that: The water-soluble resin is an acrylic resin containing hydroxyl groups and has a molecular weight of 5000-20000.

8. A method for preparing the protective solution according to any one of claims 5 to 7, characterized in that: The following steps are involved: Step 1: Weigh the curing agent, water-soluble resin and deionized water respectively by weight; Step 2: Stir the components at room temperature at a speed of 200-500 r / min for 1-5 hours to obtain the protective solution.

9. A method for using the protective liquid according to any one of claims 5 to 7, characterized in that: The steps include: Step 1: Add protective liquid droplets to the wafer surface and rotate at a speed of 500-1500r / min for 30-60s; Step 2: Bake the wafer with the protective liquid spin-coated on the surface at 100-130°C for 5-30 minutes to solidify the film and form a protective layer; the protective layer is formed on the front precision structure of the wafer; Step 3: Attach tape to one side of the wafer covered with the protective layer, with the adhesive tape located on the front side of the wafer; grind, polish, and thin the back side of the wafer to the required thickness; Remove the abrasive tape; Step 4: Stick a layer of blue film on the back of the wafer and cut the wafer; Step 5: After screening and rearranging the cut chips, clean the protective layer on the surface of the chips and remove the protective layer.

10. Use of the protective liquid according to any one of claims 5 to 7 for protecting the precise structure of the chip surface in multiple processes from wafer thinning to chip cutting.

Images