Wafer dicing protection fluid, method of making and using, and uses

Abstract

This application discloses a wafer dicing protective solution, its preparation method, usage method, and applications. By weight, it comprises the following components: 10-40 parts water-soluble resin, 40-70 parts ultrapure water, and 5-15 parts organic solvent. The water-soluble resin has side chains for ion exchange, each side chain consisting of a negatively charged functional group and a first metal ion. The functional group can react with a second metal ion, replacing the first metal ion in the side chain with the second metal ion. After this replacement, the water-soluble resin changes from a water-soluble state to a water-insoluble state. The dicing protective solution of this application can form a water-insoluble, highly adhesive protective coating on the wafer surface, preventing contamination caused by particles generated during wafer dicing and particles from the environment falling onto the wafer surface, thus improving wafer fabrication yield.

Description

Technical Field

[0001] This application belongs to the field of semiconductor chip dicing technology, specifically relating to wafer dicing protective liquid, its preparation method, usage method and application. Background Technology

[0002] During the dicing process, microparticles are generated at the cutting point of the ultrathin wafer. These particles are easily stirred up and fall onto the ultrathin wafer. Simultaneously, during the transfer of the cut ultrathin wafer, many environmental particles also settle on its surface, causing contamination. Furthermore, water is sprayed onto the cutting area of ​​the ultrathin wafer during the cutting process to cool it down. The high-speed rotating dicing wheel generates a powerful water jet carrying cutting debris, which splashes onto the ultrathin wafer surface, causing scratches and further reducing the wafer's yield. Summary of the Invention

[0003] Purpose of application: This application provides a wafer dicing protective liquid, its preparation method, usage method and application, in order to solve the problem of decreased yield of ultrathin wafers caused by particles generated during ultrathin wafer dicing and particles in the environment falling onto the surface of ultrathin wafers and debris generated during dicing scratching the surface of ultrathin wafers.

[0004] Technical solution: This application provides a wafer dicing protective liquid, which, by weight, comprises the following components: 10-40 parts of water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of organic solvent.

[0005] The water-soluble resin has side chains for ion exchange, the side chains being composed of a functional group containing a negative charge and a first metal ion; the functional group is capable of reacting with a second metal ion, causing the first metal ion in the side chain to be replaced by the second metal ion, and the water-soluble resin changes from a water-soluble state to a water-insoluble state after the replacement.

[0006] In some embodiments, the affinity of the second metal ion is greater than that of the first metal ion.

[0007] In some embodiments, the first metal ion is selected from sodium ions; the second metal ion is selected from potassium ions.

[0008] In some embodiments, the functional group is selected from any one of sulfonic acid group, phosphoric acid group, phosphorous acid group, carboxyl group, and phenolic group; or

[0009] The side chain is selected from any one of sodium sulfonate, sodium phosphate, sodium phosphite, sodium carboxylate, and sodium phenolate.

[0010] In some embodiments, the water-soluble resin is any one of sodium polystyrene sulfonate, sodium polyacrylate, sodium polymethacrylate, sodium polyethylene sulfonate, and sodium anisole sulfonate; or

[0011] The number average molecular weight of the water-soluble resin is 10,000 to 100,000.

[0012] In some embodiments, the organic solvent is selected from at least one of propylene glycol methyl ether, ethylene glycol butyl ether, ethylene glycol propyl ether, ethylene glycol ethyl ether, isopropanol, and ethanol.

[0013] In some embodiments, this application also provides a method for preparing the wafer dicing protective fluid, comprising:

[0014] Weigh 10-40 parts of water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of organic solvent, mix and stir to obtain the wafer dicing protective solution.

[0015] In some embodiments, this application also provides a method for using a wafer dicing protective fluid, including:

[0016] Apply the cutting protective fluid to the wafer surface;

[0017] After the surface of the cutting protective liquid dries, continue to coat with a salt solution containing the second metal ions, and let it stand until the cutting protective liquid is completely dry and forms a protective layer.

[0018] The wafer with the protective layer on its surface is cut and cleaned before proceeding to the next process.

[0019] In some embodiments, the salt in the salt solution containing the second metal ion is selected from at least one of potassium chloride and potassium sulfate;

[0020] The concentration of the salt solution of the second metal ion is 5–10 wt%.

[0021] In some embodiments, this application also provides the use of a wafer dicing protective fluid in wafer dicing.

[0022] Compared with the prior art, the beneficial effects of this application are as follows: The wafer dicing protective solution of this application, by weight, comprises the following components: 10-40 parts of water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of organic solvent; the water-soluble resin has side chains for ion exchange, the side chains being composed of functional groups containing negative charges and a first metal ion; the functional groups can react with a second metal ion, causing the first metal ion in the side chain to be replaced by the second metal ion, and the water-soluble resin changes from a water-soluble state to a water-insoluble state after the replacement. Because the dicing protective solution of this application can change from a water-soluble state to a water-insoluble state, it can form a water-insoluble, highly adhesive protective coating on the wafer surface, which can prevent contamination caused by particles generated during wafer dicing and particles from the environment falling onto the wafer surface, and can also prevent debris generated during dicing from scratching the wafer surface, thus significantly improving the wafer fabrication yield.

[0023] This application also provides a method for using a wafer dicing protective solution, including: applying the dicing protective solution to the wafer surface; after the surface of the dicing protective solution dries, continuing to coat it with a salt solution containing a second metal ion, allowing it to stand until the dicing protective solution is completely dry and forms a protective layer; dicing and cleaning the wafer with the protective layer on its surface, and proceeding to the next process. This application's method utilizes the principle of ion exchange. By coating with a salt solution containing a second metal ion, the water-soluble resin is converted into a water-insoluble, highly adhesive, hard, transparent, and smooth protective coating, improving the protection of the wafer. Furthermore, the coating achieves sufficient water resistance and adhesion simply by spin-drying, eliminating the need for baking and simplifying the operation.

[0024] It is understood that the preparation method and use of the wafer dicing protective liquid provided in the embodiments of this application have all the technical features and beneficial effects of the wafer dicing protective liquid described above, and will not be repeated here. Attached Figure Description

[0025] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0026] Figure 1 These are photos of adhesion verification in Example 1;

[0027] Figure 2 This is a photo verifying the adhesion of Comparative Example 1;

[0028] Figure 3 This is a photomicrograph of the cut surface in Example 1 magnified 200 times;

[0029] Figure 4 This is a micrograph of the cut surface magnified 200 times in Comparative Example 1. Detailed Implementation

[0030] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0031] In the description of this application, it should be noted that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0032] The following disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure of this application, the components and arrangements of specific examples are described below. Of course, these are merely examples and are not intended to limit this application.

[0033] After processing, the wafer needs to undergo a dicing process in the packaging step to become a complete semiconductor chip. This process cuts the wafer into several individual hexahedral chips; this process of obtaining individual chips is called "singulaton," while the process of sawing the wafer into individual cuboids is called "die shaving." As semiconductor integration increases, wafer thickness becomes increasingly thinner, which brings considerable challenges to the singulaton process.

[0034] During the dicing process, microparticles are generated at the cut point of the ultrathin wafer. These particles are easily stirred up and fall onto the ultrathin wafer. Simultaneously, during the transfer of the cut ultrathin wafer, many environmental particles also settle on its surface, causing contamination. Furthermore, water is sprayed onto the dicing area to cool it during the dicing process. The high-speed rotating dicing wheel generates a water stream with considerable impact force, carrying cutting debris. This water splashes onto the ultrathin wafer surface, causing scratches and further reducing the yield rate. Additionally, the surface of the device formed on the wafer is covered with an oxide film. During dicing, this oxide film partially cracks and peels off, scattering and causing scratches on the ultrathin wafer surface. Particularly in camera imaging elements (image sensors), even small amounts of cutting debris or adhesive flakes as described above adhering to the lens (sensor pixel) on the device (chip) surface, or damaging the pixel, can degrade device performance and become a major cause of increased defect rates. Therefore, it is quite important to avoid the problem of reduced yield of ultrathin wafers caused by particles generated during ultrathin wafer dicing and particles in the environment falling onto the surface of the ultrathin wafer, as well as by debris generated during dicing scratching the surface of the ultrathin wafer.

[0035] This application provides a wafer dicing protective solution, comprising the following components by weight: 10-40 parts of water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of organic solvent; the water-soluble resin has side chains for ion exchange, the side chains being composed of functional groups containing negative charges and a first metal ion; the functional groups are capable of reacting with a second metal ion, causing the first metal ion in the side chain to be replaced by the second metal ion, and the water-soluble resin changes from a water-soluble state to a water-insoluble state after the replacement.

[0036] Understandably, the cutting protective liquid provided in this application utilizes the principle of ion exchange to transform water-soluble resin into water-insoluble resin, resulting in a coating with high adhesion. The water-soluble resin used has side chains that undergo ion exchange reactions. Before the ion exchange reaction, the water-soluble resin can be uniformly coated onto the wafer surface to form a film. After the ion exchange reaction, the resin changes from water-soluble to water-insoluble. This water-insoluble resin forms a highly adhesive, hard, transparent, and smooth protective coating on the wafer surface, protecting the wafer throughout the entire cutting process. This prevents particles generated during ultrathin wafer cutting and particles from the environment from falling onto the ultrathin wafer surface, as well as preventing debris from scratching the ultrathin wafer surface, thus improving the yield rate of ultrathin wafer fabrication.

[0037] In some embodiments, the preferred wafer dicing protective solution comprises, by weight, the following components: 15-35 parts water-soluble resin, 50-60 parts ultrapure water, and 5-10 parts organic solvent.

[0038] In some embodiments, the functional group is selected from any one of sulfonic acid group, phosphoric acid group, phosphorous acid group, carboxyl group, and phenolic group. It is understood that the functional group in the side chain carries a negative charge, and the counterion carries a positive charge, allowing it to undergo exchange reactions with cations or positively charged compounds in solution. Based on the strength of the charged groups, they can be classified into strong acid type (sulfonic acid group), moderately strong acid type (phosphoric acid group and phosphorous acid group), and weak acid type (carboxyl group and phenolic group).

[0039] In some embodiments, the affinity of the second metal ion is greater than that of the first metal ion. It is understood that the greater affinity of the second metal ion than the first metal ion is a key factor in the occurrence of ion exchange reactions. The affinity of a metal ion refers to the strength of the interaction between the metal ion and electrons; it can also be understood as the tendency of a metal atom to lose electrons and form a positively charged ion. The affinity of a metal ion is influenced by various factors, including the electron configuration and atomic radius of the metal atom.

[0040] It should be further explained that the ion exchange reaction occurs because of the thermal motion of exchangeable ions on the functional groups, which can move freely within the resin network structure. When the second metal ion carries the same charge as the first metal ion on the resin side chain and diffuses into the resin, and the affinity of the second metal ion is greater than that of the first metal ion, an exchange reaction will occur.

[0041] In some embodiments, the first metal ion is selected from sodium ions, and the second metal ion is selected from potassium ions. The greater the charge of an ion, the greater its affinity; therefore, potassium ions have a greater affinity than sodium ions. When the charges are the same, the larger the ionic radius, the greater the affinity; therefore, potassium ions have a greater affinity than sodium ions.

[0042] Furthermore, generally speaking, the greater the affinity, the smaller the dissociation constant, indicating that electrolyte molecules are less likely to dissociate into ions. + The affinity of both is greater than that of Na. + The dissociation constants are all less than Na. + Therefore, it has low solubility in water. This also explains why substances that are soluble in water, such as sodium polystyrene sulfonate, have low solubility in water when combined with K. + The reason why the coating becomes insoluble in water after ion exchange.

[0043] In some embodiments, the side chain is selected from any one of sodium sulfonate, sodium phosphate, sodium phosphite, sodium carboxylate, and sodium phenolate. Sodium sulfonate is preferred.

[0044] In some embodiments, the water-soluble resin is any one of sodium polystyrene sulfonate (CAS No. 25704-18-1), sodium polyacrylate (CAS No. 9003-04-7), sodium polymethacrylate (CAS No. 25086-62-8), sodium polyethylene sulfonate (CAS No. 9002-97-5), and sodium anisole sulfonate (CAS No. 52993-95-0). It is understood that the sodium sulfonate groups give the resin water solubility, ensuring uniform film formation of the cutting protective solution on the wafer surface, and the structure of sodium sulfonate allows for ion exchange. During ion exchange, such as K... + It diffuses from the solution to the resin surface, enters the active sites inside the resin from the resin surface, and undergoes a metathesis reaction with the resin containing sodium sulfonate groups at the active sites, desorbing the Na+ ions. + The exchanged potassium sulfonate diffuses from the interior of the resin to its surface and further into the solution; the resin contains poorly soluble potassium sulfonate, thus altering its solubility. It should be further noted that all of the above-mentioned water-soluble resins are commercially available.

[0045] In some embodiments, the number average molecular weight of the water-soluble resin is 10,000 to 100,000. It is understood that the number average molecular weight of the water-soluble resin is any one or any two of the values ​​of 10,000, 30,000, 50,000, 70,000, and 100,000.

[0046] In some embodiments, the organic solvent is selected from at least one of propylene glycol methyl ether, ethylene glycol butyl ether, ethylene glycol propyl ether, ethylene glycol ethyl ether, isopropanol, and ethanol.

[0047] In some embodiments, a method for preparing a wafer dicing protective solution is provided, comprising: weighing 10-40 parts of water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of organic solvent, mixing and stirring to obtain the wafer dicing protective solution.

[0048] In some embodiments, the stirring time is 3 to 5 hours. The stirring time is any one of 3 hours, 4 hours, and 5 hours, or a range between any two values.

[0049] In some embodiments, the stirring rate is 200–500 rpm. The stirring speed is any one or a range between any two of 200 rpm, 300 rpm, 400 rpm, and 500 rpm.

[0050] In some embodiments, this application also provides a method for using a wafer dicing protective fluid, including:

[0051] Apply the cutting protective fluid to the wafer surface;

[0052] After the surface of the cutting protective liquid dries, continue to coat with a salt solution containing the second metal ions, and let it stand until the cutting protective liquid is completely dry and forms a protective layer.

[0053] The wafer with the protective layer on its surface is cut and cleaned before proceeding to the next process.

[0054] In some embodiments, the protective liquid used in the method of this embodiment utilizes the principle of ion exchange to convert a water-soluble resin containing sodium sulfonate groups into a water-insoluble resin, which can form a hard, transparent, and smooth protective coating that is water-insoluble and has high adhesion. The coating can obtain sufficient water resistance and adhesion by spin drying, without the need for baking, and the operation is simple.

[0055] In some embodiments, the specific steps for coating the wafer surface with the cutting protective liquid are as follows: 10 mL to 50 mL of the cutting protective liquid is dropped onto the surface of the ultrathin wafer, and a spin coater is used to rotate the wafer at a speed of 500-1000 r / min for 60-90 seconds.

[0056] In some embodiments, after the surface of the cutting protective liquid dries, a salt solution containing a second metal ion is applied, and the mixture is left to stand until the cutting protective liquid is completely dry and a protective layer is formed. Specifically, this includes: spraying a potassium salt aqueous solution onto the surface of the dried protective liquid, such as potassium chloride or potassium sulfate aqueous solution, at a concentration of 5-10 wt%, and allowing it to stand for 2-5 minutes; the spraying of the potassium salt solution can induce an ion exchange reaction without additional conditions. The reason for first spin-coating the water-soluble resin and then performing the ion exchange is that after the ion exchange, the resin precipitates out of the system and cannot form a film. The potassium ions and the sodium ions ionized from the sodium sulfonate groups on the polymer chain undergo ion exchange. The sodium sulfonate is converted into potassium sulfonate through ion exchange. Potassium sulfonate has poor water solubility, making the resin insoluble in water.

[0057] In some embodiments, the preferred second metal ion is potassium ion. Potassium ion exchange makes the resin insoluble in water and enables the coating to acquire water resistance.

[0058] In some embodiments, the ultrathin wafer with a protective layer on its surface is cut into individual grains, which can prevent the surface of the ultrathin wafer from being contaminated or damaged during cutting. After cleaning, it can proceed to the next process.

[0059] In some embodiments, this application also provides the use of wafer dicing protective fluid in wafer dicing. Wafer dicing (dicing) refers to the process of cutting a single wafer into multiple independent chips. This process is performed after all semiconductor manufacturing processes on the wafer have been completed, in order to facilitate subsequent packaging and testing. There are many dicing methods, generally including mechanical dicing and laser dicing. Mechanical dicing uses diamond blades to physically cut the wafer. The diamond blades cut the wafer at high speed, and the heat and debris generated are carried away by water flow. The high-speed rotating dicing wheel generates a water flow with a certain impact force, carrying cutting debris. This water splashes onto the surface of the ultrathin wafer, causing scratches. At the same time, particles generated during dicing and particles from the environment fall onto the surface of the ultrathin wafer. All of these problems will further reduce the wafer yield. The protective liquid provided in this application can form a water-insoluble, highly adhesive, hard, transparent, and smooth protective coating on the wafer surface. This coating protects the precision components on the wafer surface throughout the entire cutting process, preventing particles generated during ultra-thin wafer cutting and particles from the environment from falling onto the ultra-thin wafer surface, as well as preventing debris from scratching the surface and causing a decrease in the yield of ultra-thin wafers. This protective method for ultra-thin wafer cutting has excellent application prospects and large-scale industrial application potential in the field of ultra-thin wafer cutting.

[0060] In some embodiments, the deionized water is deionized water with a resistance ≥18MΩ.

[0061] It should be noted that all raw materials used in the following examples are commercially available. The range of molecular weights described does not represent the exact molecular weight, but rather a suitable fluctuation range (molecular weight can be determined using various viscosity methods).

[0062] Example 1

[0063] A wafer dicing protective solution is provided, comprising, by weight, 25 parts water-soluble resin, 55 parts ultrapure water, and 10 parts organic solvent; wherein the water-soluble resin is sodium polystyrene sulfonate resin, with the following specific structural formula: The molecular weight is 70,000; the organic solvent is propylene glycol methyl ether.

[0064] The preparation process of the wafer dicing protective solution is as follows: 25 parts of water-soluble resin, 55 parts of ultrapure water, and 10 parts of organic solvent are mixed and stirred for 3 hours to obtain the solution.

[0065] The process of using the wafer dicing protective solution is as follows: 30 mL of the dicing protective solution prepared above is dropped onto the surface of the ultrathin wafer and rotated at a speed of 500 r / min for 80 s using a spin coater; a 10 wt% potassium chloride solution is sprayed onto the surface of the surface-dried protective solution, and the wafer is allowed to stand for 3 min to dry to form a protective layer before proceeding to the subsequent dicing process.

[0066] Example 2

[0067] A wafer dicing protective solution is provided, comprising, by weight, 10 parts water-soluble resin, 40 parts ultrapure water, and 15 parts organic solvent; wherein the water-soluble resin is sodium polyacrylate, with the following specific structural formula: The molecular weight is 100,000; the organic solvent is propylene glycol methyl ether.

[0068] The preparation process of the wafer dicing protective solution is as follows: 10 parts of water-soluble resin, 40 parts of ultrapure water, and 15 parts of organic solvent are mixed and stirred for 3 hours to obtain the solution.

[0069] The process of using the wafer dicing protective solution is as follows: 30 mL of the dicing protective solution prepared above is dropped onto the surface of the ultrathin wafer and rotated at a speed of 500 r / min for 80 s using a spin coater; a 10 wt% potassium chloride solution is sprayed onto the surface of the surface-dried protective solution, and the wafer is allowed to stand for 3 min to dry to form a protective layer before proceeding to the subsequent dicing process.

[0070] Example 3

[0071] A wafer dicing protective solution is provided, comprising, by weight, 40 parts water-soluble resin, 70 parts ultrapure water, and 5 parts organic solvent; wherein the water-soluble resin is sodium polymethacrylate, with the following specific structural formula: The molecular weight is 10,000; the organic solvent is propylene glycol methyl ether.

[0072] The preparation process of the wafer dicing protective solution is as follows: 40 parts of water-soluble resin, 70 parts of ultrapure water, and 5 parts of organic solvent are mixed and stirred for 3 hours to obtain the solution.

[0073] The process of using the wafer dicing protective solution is as follows: 30 mL of the dicing protective solution prepared above is dropped onto the surface of the ultrathin wafer and rotated at a speed of 500 r / min for 80 s using a spin coater; a 10 wt% potassium chloride solution is sprayed onto the surface of the surface-dried protective solution, and the wafer is allowed to stand for 3 min to dry to form a protective layer before proceeding to the subsequent dicing process.

[0074] Example 4

[0075] A wafer dicing protective solution is provided, comprising, by weight, 15 parts water-soluble resin, 50 parts ultrapure water, and 5 parts organic solvent; wherein the water-soluble resin is sodium polyvinyl sulfonate, with the following specific structural formula: The molecular weight is 10,000; the organic solvent is propylene glycol methyl ether.

[0076] The preparation process of the wafer dicing protective solution is as follows: 15 parts of water-soluble resin, 50 parts of ultrapure water, and 5 parts of organic solvent are mixed and stirred for 3 hours to obtain the solution.

[0077] The process of using the wafer dicing protective solution is as follows: 10 mL of the dicing protective solution prepared above is dropped onto the surface of the ultrathin wafer and rotated at a speed of 1000 r / min for 60 s using a spin coater; a 5 wt% potassium chloride solution is sprayed onto the surface of the surface-dried protective solution, and the wafer is allowed to stand for 2 min. After drying, a protective layer is formed and the wafer is then used in the subsequent dicing process.

[0078] Example 5

[0079] A wafer dicing protective solution is provided, comprising, by weight, 35 parts water-soluble resin, 60 parts ultrapure water, and 15 parts organic solvent; wherein the water-soluble resin is sodium polyanisole sulfonate, with the following specific structural formula: The molecular weight is 10,000; the organic solvent is propylene glycol methyl ether.

[0080] The preparation process of the wafer dicing protective solution is as follows: 35 parts of water-soluble resin, 60 parts of ultrapure water, and 15 parts of organic solvent are mixed and stirred for 3 hours to obtain the solution.

[0081] The process of using the wafer dicing protective solution is as follows: 50 mL of the dicing protective solution prepared above is dropped onto the surface of the ultrathin wafer and rotated at a speed of 800 r / min for 90 s using a spin coater; an 8 wt% potassium chloride solution is sprayed onto the surface of the surface-dried protective solution, and the wafer is allowed to stand for 5 min to dry to form a protective layer before proceeding to the subsequent dicing process.

[0082] Comparative Example 1

[0083] A wafer dicing protective solution is provided, comprising, by weight, 25 parts of water-soluble resin, 55 parts of ultrapure water, and 10 parts of organic solvent; wherein the water-soluble resin does not contain side chains for ion exchange, specifically polyvinyl alcohol.

[0084] The wafer dicing protective solution prepared in Comparative Example 1 was directly coated onto the wafer surface. After the surface dried and formed a film, the subsequent dicing process was carried out.

[0085] Comparative Example 2

[0086] A wafer dicing protective solution is provided, with the same specific components as in Example 1. The difference lies in the application process: potassium chloride solution is not sprayed onto the already dried protective solution surface.

[0087] See Figure 1 and Figure 2 The images show the adhesion verification of the cutting protective fluid in Example 1 and Comparative Example 1, respectively. It can be seen that... Figure 1 After the rotary spray test, the protective film remained intact and did not expose the bright silicon substrate, indicating that the adhesion of Example 1 met the requirements. Figure 2After the rotational spray test, the protective film partially peeled off, exposing a bright silicon substrate, indicating that the adhesion of Comparative Example 1 was insufficient.

[0088] See further Figure 3 After using the cutting protective liquid of Example 1, the white bright edge in the 200x magnified photomicrograph of the cutting path is the edge of the protective layer. It can be seen that after cutting, the edge of the protective layer of Example 1 almost completely coincides with the cutting path and does not extend outward along the cutting path, which can effectively protect the edge position of the chip.

[0089] See further Figure 4 After using the cutting protective liquid of Comparative Example 1, the white bright edge in the 200x magnified micrograph of the cutting path is the edge of the protective layer. It can be seen that after cutting, the edge of the protective film in Comparative Example 1 obviously extends outward along the cutting path and cannot protect the edge of the chip.

[0090] Water resistance and adhesion tests were conducted on the wafer dicing protective solutions of Examples 1-5 and Comparative Example 1. The specific structures are shown in Table 1.

[0091] The water resistance test method is as follows: the test piece (dummy piece) with the protective layer formed by ion exchange is immersed in pure water for 60 minutes, and the protective film is observed to change during the immersion process; then the dummy piece is taken out and spun dry, and the protective film is observed to fall off; if the protective film does not change or fall off during immersion or after spun dry, it indicates that its water resistance meets the requirements.

[0092] The adhesion test method is as follows: the Dummy sheet with the protective layer formed by ion exchange is cut into 6mm*4mm size using an ultra-thin wafer dicing machine. During the cutting process, water is sprayed onto the cutting wheel to cool it down. After the cutting is completed, the Dummy sheet is dried. If the protective film on the Dummy sheet does not fall off, it indicates that its adhesion meets the requirements.

[0093] Table 1

[0094] Water resistance test Adhesion test Example 1 Meets requirements Meets requirements Example 2 Meets requirements Meets requirements Example 3 Meets requirements Meets requirements Example 4 Meets requirements Meets requirements Example 5 Meets requirements Meets requirements Comparative Example 1 Shedding Shedding Comparative Example 2 Shedding Shedding

[0095] As shown in Table 1, compared with Comparative Examples 1 and 2, the cutting protective liquids of Examples 1-5, due to the side chains of the water-soluble resin used for ion exchange, after undergoing an ion exchange reaction with a salt solution containing the second metal ion, change the water-soluble resin from a water-soluble state to a water-insoluble state. This allows the formation of a hard, transparent, and smooth protective coating on the wafer surface that is insoluble in water and has high adhesion. This protects the wafer throughout the entire cutting process, preventing particles generated during ultrathin wafer cutting and particles from the environment from falling onto the surface of the ultrathin wafer, as well as preventing debris generated during cutting from scratching the surface of the ultrathin wafer and causing a decrease in the yield of ultrathin wafers.

[0096] The wafer dicing protective liquid, its preparation method, usage method, and applications provided in the embodiments of this application have been described in detail above. Specific examples have been used in this application to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A protective layer for wafer dicing, characterized in that, Apply wafer dicing protective fluid to the wafer surface; After the surface of the wafer dicing protective solution dries, a salt solution containing the second metal ions is applied and allowed to stand until the wafer dicing protective solution is completely dry and the protective layer is formed. By weight, the wafer dicing protective solution comprises the following components: 10-40 parts water-soluble resin, 40-70 parts ultrapure water, and 5-15 parts organic solvent. The water-soluble resin has side chains for ion exchange, the side chains being composed of functional groups containing negative charges and a first metal ion; the functional groups are capable of reacting with a second metal ion, causing the first metal ion in the side chain to be replaced by the second metal ion, and the water-soluble resin changes from a water-soluble state to a water-insoluble state after the replacement. The first metal ion is selected from sodium ions; the second metal ion is selected from potassium ions; The functional group is selected from any one of sulfonic acid group, phosphoric acid group, phosphorous acid group, carboxyl group, and phenolic group; The side chain is selected from any one of sodium sulfonate, sodium phosphate, sodium phosphite, sodium carboxylate, and sodium phenolate.

2. The protective layer for wafer dicing according to claim 1, characterized in that, The water-soluble resin is any one of sodium polystyrene sulfonate, sodium polyacrylate, sodium polymethacrylate, sodium polyethylene sulfonate, and sodium anisole sulfonate.

3. The protective layer for wafer dicing according to claim 1, wherein The number average molecular weight of the water-soluble resin is 10,000 to 100,000.

4. The protective layer for wafer dicing according to claim 1, wherein The organic solvent is selected from at least one of propylene glycol methyl ether, ethylene glycol butyl ether, ethylene glycol propyl ether, ethylene glycol ethyl ether, isopropanol, and ethanol.

5. The protective layer for wafer dicing according to claim 1, wherein The method for preparing the wafer dicing protective fluid includes: Weigh 10-40 parts of water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of organic solvent, mix and stir to obtain the wafer dicing protective solution.

6. The protective layer for wafer dicing according to claim 1, wherein The salt in the salt solution containing the second metal ion is selected from at least one of potassium chloride and potassium sulfate.

7. The protective layer for wafer dicing according to claim 1, wherein The concentration of the salt solution containing the second metal ion is 5-10 wt%.

8. Use of a protective layer for wafer dicing according to any one of claims 1-7 in wafer dicing.

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