Wafer cutting protection liquid as well as preparation method, use method and application thereof

Abstract

The invention discloses a wafer cutting protection liquid as well as a preparation method, a use method and application thereof, and the wafer cutting protection liquid comprises the following components in parts by mass: 10-40 parts of water-soluble resin, 40-70 parts of ultrapure water and 5-15 parts of an organic solvent, the water-soluble resin has a side chain for ion exchange, and the side chain is composed of a functional group containing negative charges and first metal ions; the functional group can react with the second metal ion, so that the first metal ion in the side chain is replaced by the second metal ion, and the water-soluble resin is changed into a water-insoluble state from a water-soluble state after replacement. The cutting protective liquid can form a protective coating which is insoluble in water and high in adhesive force on the surface of a wafer, pollution caused by falling of particles generated during wafer cutting and particles in the environment on the surface of the wafer can be avoided, and the preparation yield of the wafer is increased.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor chip cutting technology, and specifically relates to wafer cutting protection liquid, its preparation method, use method and purpose. Background Art

[0002] During the process of wheel cutting, particles will be generated at the cutting point of the ultra-thin wafer, and these particles are easily lifted and dropped onto the ultra-thin wafer. At the same time, during the transfer process of the cut ultra-thin wafer, many particles in the environment will fall on the surface of the ultra-thin wafer, causing pollution. At the same time, during the cutting process, water will be sprayed on the wheel and the cutting point of the ultra-thin wafer to cool it down. The high-speed rotating wheel will generate a water flow with a certain impact force and containing cutting debris. The water flow splashed onto the surface of the ultra-thin wafer will cause scratches, resulting in a further decrease in the qualified rate of the wafer. Summary of the invention

[0003] Purpose of application: This application provides a wafer cutting protection liquid, its preparation method, use method and purpose, in order to solve the problem that the ultra-thin wafer qualification rate is reduced due to particles generated during ultra-thin wafer cutting and particles in the environment falling on the surface of the ultra-thin wafer and debris generated during cutting scratching the surface of the ultra-thin wafer.

[0004] Technical solution: The present application provides a wafer cutting protection liquid, which comprises the following components, measured by mass: 10-40 parts of a water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of an organic solvent;

[0005] The water-soluble resin has a side chain for ion exchange, and the side chain is composed of a functional group containing a negative charge and a first metal ion; the functional group can react with a second metal ion, so that the first metal ion in the side chain is 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 the affinity of the first metal ion.

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

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

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

[0010] In some embodiments, the water-soluble resin is any one of sodium polystyrene sulfonate, sodium polyacrylate, sodium polymethacrylate, sodium polyethylene sulfonate, and sodium polyanisole 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, the present application also provides a method for preparing the wafer cutting protection liquid, comprising:

[0014] 10-40 parts of water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of organic solvent are weighed respectively, mixed and stirred to obtain the wafer cutting protection liquid.

[0015] In some embodiments, the present application also provides a method for using a wafer cutting protection liquid, comprising:

[0016] Applying a cutting protection liquid on the surface of the wafer;

[0017] After the surface of the cutting protection liquid is dry, continue to apply the salt solution containing the second metal ion and let it stand until the cutting protection liquid is completely dry to form a protective layer;

[0018] The wafer with the protective layer on the surface is cut and cleaned before entering 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 second metal ion salt solution is 5-10 wt %.

[0021] In some embodiments, the present application also provides a use of a wafer cutting protection liquid in wafer wheel cutting.

[0022] Compared with the prior art, the beneficial effect of the present application is that: a wafer cutting protection liquid of the present application includes the following components by mass: 10-40 parts of a water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of an organic solvent; the water-soluble resin has a side chain for ion exchange, and the side chain is composed of a functional group containing a negative charge and a first metal ion; the functional group can react with the second metal ion, so that the first metal ion in the side chain is 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. Since the cutting protection liquid of the present application can change from a water-soluble state to a water-insoluble state, it can form a layer of water-insoluble and highly adhesive protective coating on the surface of the wafer, which can avoid the pollution caused by particles generated during wafer cutting and particles in the environment falling on the surface of the wafer, and can also prevent the debris generated during cutting from scratching the surface of the wafer, which can greatly improve the preparation yield of the wafer.

[0023] The present application also provides a method for using a wafer cutting protection liquid, including: applying the cutting protection liquid to the surface of the wafer; after the surface of the cutting protection liquid is dry, continue to apply a salt solution containing a second metal ion, and let it stand until the cutting protection liquid is completely dry to form a protective layer; cut and clean the wafer with a protective layer on the surface, and enter the next process. The method of use of the present application utilizes the principle of ion exchange. By applying a salt solution containing a second metal ion, the water-soluble resin is converted into a hard, transparent and smooth protective coating that is insoluble in water and has high adhesion, thereby improving the protection of the wafer. In the method of use, the coating can obtain sufficient water resistance and adhesion by spin drying, without the need for baking, and is easy to operate.

[0024] It can be understood that the preparation method and use of the wafer cutting protection liquid provided in the embodiment of the present application have all the technical features and beneficial effects of the above-mentioned wafer cutting protection liquid, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0026] Figure 1 This is a photo of adhesion verification of Example 1;

[0027] Figure 2 This is a photo to verify the adhesion of Example 1;

[0028] Figure 3 This is a micrograph of the cutting path of Example 1 magnified 200 times;

[0029] Figure 4 This is a micrograph of the cutting path of Comparative Example 1 magnified 200 times. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0031] In the description of the present application, it should be noted that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise specified, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present application, the term "including" means "including but not limited to". The various embodiments of the present application may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and simplicity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within the 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which are applicable regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any quoted numbers (fractions or integers) within the indicated range.

[0032] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0033] The processed wafer needs to go through the cutting process in the packaging process to become a complete semiconductor chip. In this process, the wafer will be cut into several hexahedral individual chips. This process of obtaining independent chips is called "singulaton", and the process of sawing the wafer into independent rectangular blocks is called "die sawing". With the improvement of semiconductor integration, the thickness of wafers is getting thinner and thinner, which also brings a lot of difficulty to the "singularization" process.

[0034] In the process of wheel cutting, particles will be generated at the cutting point of the ultra-thin wafer, and these particles are easily lifted and fall onto the ultra-thin wafer. At the same time, many particles in the environment will fall on the surface of the ultra-thin wafer during the transfer process after cutting, causing pollution. In addition, during the cutting process, water will be sprayed on the cutting point of the wheel and the ultra-thin wafer to cool down. The high-speed rotating wheel will produce a water flow with a certain impact force and entrained with cutting debris. The water flow splashes on the surface of the ultra-thin wafer and scratches it, resulting in a further decrease in the qualified rate. In addition, the surface of the device formed on the wafer is covered with an oxide film. During cutting, the oxide film is partially cracked and peeled off. The peeled oxide film scatters and splashes, causing scratches on the surface of the ultra-thin wafer. In particular, in the imaging element (image sensor) used for the camera, even if a small amount of the cutting debris or fine pieces of adhesive as described above are attached to the lens (sensor pixel part) on the surface of the device (chip), or the pixel part is damaged, the performance of the element will be reduced, which will become the main reason for the increase in the defective rate. Therefore, it is very important to prevent particles generated during ultra-thin wafer cutting and particles in the environment from falling on the surface of the ultra-thin wafer, and to prevent debris generated during cutting from scratching the surface of the ultra-thin wafer, thereby reducing the yield of ultra-thin wafers.

[0035] An embodiment of the present application provides a wafer cutting protection liquid, which includes the following components, measured by mass: 10-40 parts of a water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of an organic solvent; the water-soluble resin has a side chain for ion exchange, and the side chain is composed of a functional group containing a negative charge and a first metal ion; the functional group can react with the second metal ion, so that the first metal ion in the side chain is 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] It is understandable that the cutting protection liquid provided by the present application utilizes the principle of ion exchange to convert the water-soluble resin into a water-insoluble one, and the formed coating has high adhesion. Among them, the water-soluble resin used has a side chain of ion exchange reaction. Before the ion exchange reaction occurs, the water-soluble resin can be evenly coated on the surface of the wafer to form a film; after the ion exchange reaction occurs, the resin changes from water-soluble to water-insoluble, and the water-insoluble resin can form a hard, transparent and smooth protective coating with high adhesion on the surface of the wafer, which plays a role in protecting the wafer during the whole process of blade cutting, avoiding the particles generated during the cutting of ultra-thin wafers and the particles in the environment from falling on the surface of the ultra-thin wafer, and the debris generated during the cutting scratches the surface of the ultra-thin wafer, thereby improving the qualified rate of ultra-thin wafer preparation.

[0037] In some embodiments, a preferred wafer cutting protection liquid includes the following components, in parts by mass: 15-35 parts of a water-soluble resin, 50-60 parts of ultrapure water, and 5-10 parts of an organic solvent.

[0038] In some embodiments, the functional group is selected from any one of sulfonic acid, phosphoric acid, phosphite, carboxyl, and phenol. It is understood that the functional group in the side chain is negatively charged, and the counterion is positively charged, and can exchange with cations or positively charged compounds in the solution. According to the strength of the charge group, it can be divided into strong acid type (sulfonic acid group), medium strong acid type (phosphite and phosphoric acid group) and weak acid type (carboxyl and phenol).

[0039] In some embodiments, the affinity of the second metal ion is greater than the affinity of the first metal ion. It is understood that the affinity of the second metal ion is greater than the affinity of the first metal ion, which is a key factor for the ion exchange reaction to occur. The affinity of the metal ion refers to the interaction strength between the metal ion and the electron, and can also be understood as the tendency of the metal atom to lose electrons and form a positively charged ion. The affinity of the metal ion is affected by many factors, including the electronic configuration of the metal atom, the atomic radius, etc.

[0040] It should be further explained that the reason why ion exchange reaction can occur is the result of thermal motion of exchangeable ions on functional groups, which can move freely in the resin network structure. When the second metal ion has the same charge sign as the first metal ion on the side chain of the resin and diffuses into the interior of the resin, and the affinity of the second metal ion is greater than the affinity of the first metal ion, an exchange reaction will occur between the two.

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

[0042] Furthermore, in general, the greater the affinity, the smaller the dissociation constant, indicating that the electrolyte molecules are not easy to dissociate into ions. + The affinity of + , the dissociation constants are smaller than Na + , then the solubility in water is low. This also explains why water-soluble substances such as sodium polystyrene sulfonate are + This is 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 carboxyl, and sodium phenol, preferably sodium sulfonate.

[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 polyanisole sulfonate (CAS No. 52993-95-0). It is understood that the sodium sulfonate group makes the resin water-soluble, which can ensure the uniform film formation of the cutting protection liquid on the wafer surface, and the structure of sodium sulfonate can undergo ion exchange. In the process of ion exchange, for example, K + It diffuses from the solution to the resin surface, enters the active center inside the resin from the resin surface, and undergoes double decomposition reaction with the resin with sodium sulfonate groups at the active center to desorb the ion Na + It diffuses from the inside of the resin to the surface of the resin and further diffuses into the solution; the resin after the exchange contains potassium sulfonate with poor solubility, thereby changing the solubility of the resin. It should be further explained that the above-mentioned water-soluble resins can be obtained commercially.

[0045] In some embodiments, the number average molecular weight of the water-soluble resin is 10000 to 100000. It is understood that the number average molecular weight of the water-soluble resin is any one of 10000, 30000, 50000, 70000, 100000 or a range between any two values.

[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 cutting protection liquid is provided, comprising: weighing 10-40 parts of a water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of an organic solvent, respectively, mixing and stirring to obtain the wafer cutting protection liquid.

[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 rate is any one of 200 rpm, 300 rpm, 400 rpm, 500 rpm, or a range between any two values.

[0050] In some embodiments, the present application also provides a method for using a wafer cutting protection liquid, including:

[0051] Applying a cutting protection liquid on the surface of the wafer;

[0052] After the surface of the cutting protection liquid is dry, continue to apply the salt solution containing the second metal ion and let it stand until the cutting protection liquid is completely dry to form a protective layer;

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

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

[0055] In some embodiments, the specific steps of coating the cutting protection liquid on the wafer surface are: dropping 10mL-50mL of the cutting protection liquid onto the surface of the ultra-thin wafer, and using a spin coater to rotate at a speed of 500-1000r / min for 60-90s.

[0056] In some embodiments, after the surface of the cutting protection liquid is dried, a salt solution containing a second metal ion is continuously coated and allowed to stand until the cutting protection liquid is completely dried to form a protective layer. The steps specifically include: spraying a potassium salt aqueous solution, such as potassium chloride and potassium sulfate aqueous solution, on the surface of the dried protection liquid, with a concentration of 5 to 10 wt%, and standing for 2 to 5 minutes; an ion exchange reaction can occur by spraying the potassium salt solution without the need for additional conditions, wherein the water-soluble resin is first spin-coated and then ion exchanged because after the ion exchange, the resin is precipitated from the system and cannot form a film, and the potassium ions and the sodium ions ionized from the sodium sulfonate groups on the polymer chains undergo ion exchange, and the sodium sulfonate group is converted into the potassium sulfonate group through ion exchange. The potassium sulfonate group has poor water solubility, making the resin insoluble in water.

[0057] In some embodiments, the preferred second metal ion is potassium ion. The resin is made insoluble in water by exchanging with potassium ion, and the coating can be made water-resistant.

[0058] In some embodiments, an ultra-thin wafer with a protective layer on its surface is cut to obtain individual grains, which can prevent the surface of the ultra-thin wafer from being contaminated or damaged during cutting, and then enter the next process after cleaning.

[0059] In some embodiments, the present application also provides the use of wafer cutting protection liquid in wafer wheel cutting. Wafer scribing (cutting) refers to the process of cutting a single wafer into multiple independent chips. This process is performed after all semiconductor manufacturing processes are completed on the wafer for subsequent packaging and testing. There are many ways to scribing, generally mechanical scribing and laser scribing. Mechanical scribing uses a diamond blade to physically cut the wafer. The diamond blade cuts the wafer at high speed, and the heat and debris generated are carried away by the water flow. The high-speed rotating wheel will generate a water flow with a certain impact force that carries cutting debris. The water flow splashed onto the surface of the ultra-thin wafer will cause scratches. At the same time, the particles generated during cutting and the particles in the environment will fall on the surface of the ultra-thin wafer. The above problems will cause the wafer qualification rate to further decrease. The protective liquid provided in this application can form a layer of hard, transparent and smooth protective coating that is insoluble in water and has high adhesion on the surface of the wafer, which protects the precision devices on the surface of the wafer during the entire process of blade cutting, and prevents particles generated during ultra-thin wafer cutting and particles in the environment from falling on the surface of the ultra-thin wafer, and debris generated during cutting from scratching the surface of the ultra-thin wafer, causing the problem of a decrease in the qualified rate of ultra-thin wafers. The protection method for ultra-thin wafer cutting has very good application prospects and large-scale industrial promotion potential in the field of ultra-thin wafer cutting.

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

[0061] It should be noted that all raw materials in the following examples can be obtained from commercial sources. The molecular weight range does not mean its exact molecular weight, but a suitable range of fluctuations (for example, the molecular weight can be measured by various viscosity methods).

[0062] Example 1

[0063] Provided is a wafer cutting protection liquid, which comprises, by mass, 25 parts of a water-soluble resin, 55 parts of ultrapure water, and 10 parts of an organic solvent; wherein the water-soluble resin is sodium polystyrene sulfonate resin, and the specific structural formula is: The molecular weight is 70000; the organic solvent is propylene glycol methyl ether.

[0064] The preparation process of the wafer cutting protection liquid 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 prepare the solution.

[0065] The use process of wafer cutting protection liquid: add 30mL of the above-prepared cutting protection liquid to the surface of the ultra-thin wafer, and use a spin coater to rotate at a speed of 500r / min for 80s; spray a 10wt% potassium chloride solution on the surface of the dried protection liquid, let it stand for 3min, form a protective layer after drying, and enter the subsequent cutting process.

[0066] Example 2

[0067] Provided is a wafer cutting protection liquid, which comprises, by mass, 10 parts of a water-soluble resin, 40 parts of ultrapure water, and 15 parts of an organic solvent; wherein the water-soluble resin is sodium polyacrylate, and the specific structural formula is: The molecular weight is 100000; the organic solvent is propylene glycol methyl ether.

[0068] The preparation process of the wafer cutting protection liquid 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 prepare the solution.

[0069] The use process of wafer cutting protection liquid: add 30mL of the above-prepared cutting protection liquid to the surface of the ultra-thin wafer, and use a spin coater to rotate at a speed of 500r / min for 80s; spray a 10wt% potassium chloride solution on the surface of the dried protection liquid, let it stand for 3min, form a protective layer after drying, and enter the subsequent cutting process.

[0070] Example 3

[0071] Provided is a wafer cutting protection liquid, which comprises, by mass, 40 parts of a water-soluble resin, 70 parts of ultrapure water, and 5 parts of an organic solvent; wherein the water-soluble resin is sodium polymethacrylate, and the specific structural formula is: The molecular weight is 10000; the organic solvent is propylene glycol methyl ether.

[0072] The preparation process of the wafer cutting protection liquid 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 prepare the solution.

[0073] The use process of wafer cutting protection liquid: add 30mL of the above-prepared cutting protection liquid to the surface of the ultra-thin wafer, and use a spin coater to rotate at a speed of 500r / min for 80s; spray a 10wt% potassium chloride solution on the surface of the dried protection liquid, let it stand for 3min, form a protective layer after drying, and enter the subsequent cutting process.

[0074] Example 4

[0075] Provided is a wafer cutting protection liquid, which comprises, by weight, 15 parts of a water-soluble resin, 50 parts of ultrapure water, and 5 parts of an organic solvent; wherein the water-soluble resin is sodium polyvinyl sulfonate, and the specific structural formula is: The molecular weight is 10000; the organic solvent is propylene glycol methyl ether.

[0076] The preparation process of the wafer cutting protection liquid 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 prepare the solution.

[0077] The use process of wafer cutting protection liquid: add 10mL of the above-prepared cutting protection liquid to the surface of the ultra-thin wafer, and use a spin coater to rotate at a speed of 1000r / min for 60s; spray a 5wt% potassium chloride solution on the surface of the dried protection liquid, let it stand for 2min, form a protective layer after drying, and enter the subsequent cutting process.

[0078] Example 5

[0079] Provided is a wafer cutting protection liquid, which comprises, by weight, 35 parts of a water-soluble resin, 60 parts of ultrapure water, and 15 parts of an organic solvent; wherein the water-soluble resin is sodium polyanisyl sulfonate, and the specific structural formula is: The molecular weight is 10000; the organic solvent is propylene glycol methyl ether.

[0080] The preparation process of the wafer cutting protection liquid 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 prepare the solution.

[0081] The use process of wafer cutting protection liquid: add 50mL of the above-prepared cutting protection liquid to the surface of the ultra-thin wafer, and use a spin coater to rotate at a speed of 800r / min for 90s; spray 8wt% potassium chloride solution on the surface of the dried protection liquid, let it stand for 5min, form a protective layer after drying, and enter the subsequent cutting process.

[0082] Comparative Example 1

[0083] Provided is a wafer cutting protection liquid, which comprises, by mass, 25 parts of a water-soluble resin, 55 parts of ultrapure water, and 10 parts of an organic solvent; wherein the water-soluble resin does not contain a side chain for ion exchange, specifically polyvinyl alcohol.

[0084] The wafer cutting protection liquid prepared in Comparative Example 1 is directly coated on the surface of the wafer, and after the surface is dried to form a film, the subsequent cutting process is performed.

[0085] Comparative Example 2

[0086] A wafer cutting protection liquid is provided, and the specific components are exactly the same as those in Example 1. The difference is that during use: the potassium chloride solution is not sprayed on the surface of the protection liquid that has been dried.

[0087] See also Figure 1 and Figure 2 , are respectively the adhesion verification diagrams of the cutting protection liquid of Example 1 and Comparative Example 1. It can be seen that Figure 1 After the rotary spray test, the protective film was intact and the bright silicon substrate was not exposed, indicating that the adhesion of Example 1 could meet the requirements. Figure 2After the rotary spray test, the protective film partially fell off, exposing the silicon substrate that was bright to the naked eye, indicating that the adhesion of Comparative Example 1 could not meet the requirements.

[0088] See also Figure 3 After using the cutting protection liquid of Example 1, the white bright edge in the microphotograph of the cutting path magnified 200 times 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 overlaps with the cutting path and does not expand outward along the cutting path, which can effectively protect the edge position of the chip.

[0089] See also Figure 4 After using the cutting protection liquid of comparative example 1, the white bright edge in the microphotograph of the cutting path magnified 200 times is the edge of the protective layer. It can be seen that after cutting, the edge of the protective film of comparative example 1 obviously expands outward along the cutting path and cannot protect the edge of the chip.

[0090] The wafer cutting protection liquids of Examples 1-5 and Comparative Example 1 were subjected to water resistance tests and adhesion tests. See Table 1 for their specific structures.

[0091] Among them, the water resistance test method is: soak the test piece (Dummy piece) with a protective layer formed by ion exchange in pure water for 60 minutes, and observe whether the protective film changes during the soaking process; then take out the Dummy piece and spin dry it, and observe whether the protective film falls off; during soaking or after drying, if the protective film does not change or fall off, it indicates that its water resistance can meet the requirements.

[0092] The adhesion test method is: cut the Dummy sheet with a protective layer formed by ion exchange into a size of 6mm*4mm using an ultra-thin wafer cutting machine, spray water on the cutting wheel to cool it down during the cutting process, and spin dry the Dummy sheet after cutting. If the protective film on the Dummy sheet does not fall off, it indicates that its adhesion can meet the requirements.

[0093] Table 1

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

[0095] It can be seen from the results in Table 1 that, compared with Comparative Examples 1 and 2, the cutting protection liquid of Examples 1-5, since the water-soluble resin has a side chain for ion exchange, after undergoing an ion exchange reaction with a salt solution containing a second metal ion, the water-soluble resin changes from a water-soluble state to a water-insoluble state, and can form a hard, transparent, and smooth protective coating that is insoluble in water and has high adhesion on the surface of the wafer, thereby protecting the wafer during the entire process of blade cutting, and preventing particles generated during ultra-thin wafer cutting and particles in the environment from falling on the surface of the ultra-thin wafer, and debris generated during cutting from scratching the surface of the ultra-thin wafer, thereby reducing the pass rate of ultra-thin wafers.

[0096] The above is a detailed introduction to the wafer cutting protection liquid, its preparation method, use method and purpose provided in the embodiments of the present application. Specific examples are used in this application to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical scheme and core idea of ​​the present application; ordinary technicians in this field should understand that: they can still modify the technical schemes recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical scheme deviate from the scope of the technical scheme of the embodiments of the present application.

Claims

1. A wafer cutting protection liquid, characterized in that: The composition comprises 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 a side chain for ion exchange, and the side chain is composed of a functional group containing a negative charge and a first metal ion; the functional group can react with a second metal ion, so that the first metal ion in the side chain is 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.

2. The wafer cutting protection liquid according to claim 1, characterized in that: The affinity of the second metal ion is greater than the affinity of the first metal ion.

3. The wafer cutting protection liquid according to claim 2, characterized in that: The first metal ion is selected from sodium ions; the second metal ion is selected from potassium ions.

4. The wafer cutting protection liquid according to claim 1, characterized in that: The functional group is selected from any one of a sulfonic acid group, a phosphoric acid group, a phosphite group, a carboxyl group, and a phenolic group; or The side chain is selected from any one of sodium sulfonate, sodium phosphate, sodium phosphite, sodium carboxyl and sodium phenol.

5. The wafer cutting protection liquid according to claim 4, characterized in that: The water-soluble resin is any one of sodium polystyrene sulfonate, sodium polyacrylate, sodium polymethacrylate, sodium polyethylene sulfonate, and sodium polyanisole sulfonate; or The number average molecular weight of the water-soluble resin is 10,000 to 100,000.

6. The wafer cutting protection liquid according to claim 1, characterized in that: 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.

7. A method for preparing the wafer cutting protection liquid according to any one of claims 1 to 6, characterized in that: include: 10-40 parts of water-soluble resin, 40-70 parts of ultrapure water, and 5-15 parts of organic solvent are weighed respectively, mixed and stirred to obtain the wafer cutting protection liquid.

8. A method for using the wafer cutting protection liquid according to any one of claims 1 to 7, characterized in that: include: Applying a cutting protection liquid on the surface of the wafer; After the surface of the cutting protection liquid is dry, continue to apply the salt solution containing the second metal ion and let it stand until the cutting protection liquid is completely dry to form a protective layer; The wafer with the protective layer on the surface is cut and cleaned before entering the next process.

9. The method for using a wafer cutting protection liquid according to claim 8, characterized in that: The salt in the salt solution containing the second metal ion is selected from at least one of potassium chloride and potassium sulfate; The concentration of the salt solution containing the second metal ion is 5-10 wt %.

10. Use of the wafer cutting protection liquid according to any one of claims 1 to 6 in wafer wheel cutting.

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