A protective liquid for green light cutting and its preparation method and use

Abstract

The present application discloses a protective liquid for green light cutting, its preparation method and use. The protective liquid includes the following components, measured by mass: 20-40 parts of a water-soluble resin, 0.25-0.5 parts of a green light absorber, and 50-100 parts of a solvent; wherein the water-soluble resin includes a water-soluble polyester and sodium polystyrene sulfonate; and the green light absorber includes allura red and lac acid. The water-soluble resin of the present application is not easily etched and has a high etching selectivity, which can meet the etching depth required by the substrate with minimal loss of the protective film layer; the higher solubility of sodium polystyrene sulfonate helps to increase the resin solid content, increase the film thickness, and improve the stability of the protective liquid; in addition, the green light absorber adopts a combination of allura red and lac acid, which can ensure the stability of the solution and the photostability of the green light absorber, while increasing the amount of absorber added and the absorbance.

Description

Technical Field

[0001] The present application belongs to the field of laser cutting technology, and specifically relates to a protective liquid for green light cutting, a preparation method thereof, and an application thereof. Background Art

[0002] Several light sources are commonly used in the semiconductor wafer cutting process: red, violet, and green. Green light, with a wavelength between red and violet, offers a smaller spot size and a shorter focal length, and is a cold-processing method, making it irreplaceable in precision cutting. Currently, the protective fluids used for cutting are mostly designed to absorb violet wavelengths and have no significant absorption for green light. This results in a larger heat-affected zone (HAZ) on wafers cut with green light, potentially affecting the chip surface and significantly reducing wafer cutting yield. Summary of the Invention

[0003] Purpose of application: This application provides a protective liquid for green light cutting and its preparation method and use, so as to improve the yield and productivity in the semiconductor manufacturing process.

[0004] Technical solution: The present application provides a protective liquid for green light cutting, which comprises the following components, calculated by mass: 20-40 parts of a water-soluble resin, 0.25-0.5 parts of a green light absorber, and 50-100 parts of a solvent;

[0005] Wherein, the water-soluble resin includes water-soluble polyester and sodium polystyrene sulfonate;

[0006] The green light absorbers include allura red and lactic acid.

[0007] In some embodiments, the mass ratio of the water-soluble polyester to the sodium polystyrene sulfonate is (2-5):1.

[0008] In some embodiments, the water-soluble polyester has a glass transition temperature of 42-58°C; and / or

[0009] The number average molecular weight of the water-soluble polyester is 7000-12000; and / or

[0010] The glass transition temperature of the sodium polystyrene sulfonate is 40-50° C.; and / or

[0011] The number average molecular weight of the sodium polystyrene sulfonate is 3000-4000.

[0012] In some embodiments, the water-soluble polyester is selected from at least one of EW100G, EW100Q, EW210, and EW100D.

[0013] In some embodiments, the water-soluble polyester is a water-soluble saturated polyester resin containing a benzene ring and an ester group;

[0014] The water-soluble saturated polyester resin is selected from at least one of Korean SK saturated polyester resins Skybon EW100G, SK EW100Q, SK EW210, and SK EW100D.

[0015] In some embodiments, the mass ratio of the allura red to the lac acid is (1-4):1.

[0016] In some embodiments, the lac acid is selected from at least one of lac acid A, lac acid B, lac acid C, and lac acid E; or

[0017] The green light absorber is used to absorb light with a wavelength of 500-600 nm.

[0018] In some embodiments, the solvent is selected from at least one of deionized water, methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, isobutanol, ethyl ether, methyl ethyl ether, di-n-butyl ether, propylene glycol methyl ether, ethylene glycol propyl ether, and ethylene glycol butyl ether.

[0019] In some embodiments, the solvent consists of deionized water and ethylene glycol butyl ether; wherein the mass ratio of the deionized water to the ethylene glycol butyl ether is (30-90):(5-40).

[0020] In some embodiments, the present application further provides a method for preparing a protective liquid for green light cutting, comprising the following steps:

[0021] Weigh 20-40 parts of water-soluble resin, 0.25-0.5 parts of green light absorber and 50-100 parts of solvent respectively;

[0022] Mix the water-soluble resin, green light absorber and solvent, and stir at 40-50° C. and 200-500 rpm for 1-5 hours to obtain a protective solution for green light cutting;

[0023] The water-soluble resin includes water-soluble polyester and sodium polystyrene sulfonate; and the green light absorber includes allura red and lac acid.

[0024] In some embodiments, the present application also provides a use of a protective liquid for green light cutting in semiconductor wafer laser cutting and / or plasma cutting processes.

[0025] Beneficial effects: The present application discloses a protective liquid for green light cutting, comprising the following components, in parts by mass: 20-40 parts of a water-soluble resin, 0.25-0.5 parts of a green light absorber, and 50-100 parts of a solvent; wherein the water-soluble resin comprises a water-soluble polyester and sodium polystyrene sulfonate; and the green light absorber comprises allura red and lac acid. The water-soluble resin of the present application adopts a combination of water-soluble polyester and sodium polystyrene sulfonate, is not easily etched, has a high etching selectivity, and can meet the etching depth required by the substrate with minimal loss of the protective film layer; the higher solubility of sodium polystyrene sulfonate helps to increase the solid content of the resin, increase the thickness of the film layer, and improve the stability of the protective liquid; in addition, the green light absorber adopts a combination of allura red and lac acid, which can ensure the stability of the solution and the photostability of the green light absorber. At the same time, the amount of absorber added is increased to improve the absorbance.

[0026] It is understandable that the preparation method and use of the protective liquid for green light cutting provided in the embodiments of the present application have all the technical features and beneficial effects of the above-mentioned protective liquid, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0028] Figure 1 This is the UV spectrum of the protective solution provided in Example 1 of the present application;

[0029] Figure 2 This is the infrared spectrum of the water-soluble polyester EW210 in Example 1 of the present application;

[0030] Figure 3 This is a picture of a silicon wafer cut using the protective solution of Example 1;

[0031] Figure 4 This is a picture after silicon wafer cutting using the protective liquid of Comparative Example 3. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present application and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0033] 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", specifically refer to 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 presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood 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 the range. For example, the range description from 1 to 6 should be considered to have 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 apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any quoted number (fractional or integer) within the indicated range.

[0034] 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 components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0035] Laser cutting machines are essential tools in the cutting field, known as the fastest "knife." Their principle is to illuminate the material surface with a high-density, high-energy laser beam, causing it to melt, vaporize, ablate, or reach a ignition point. Simultaneously, a high-speed airflow coaxial with the beam blows away the molten material, thereby separating the workpiece and creating a cut. Semiconductor wafer cutting machines commonly use three light sources: red, violet, and green. Violet light has a wavelength of 355nm, red light has a wavelength of 1064nm, and green light has a wavelength of 532nm. Green light, with a wavelength between red and violet, has a smaller spot size and a shorter focal length, operating in a cold working mode. It plays an irreplaceable role in precision cutting. Currently, most protective fluids used in laser cutting absorb 355nm wavelengths. They do not significantly absorb green light (532nm wavelength). This results in a larger heat-affected zone (HAZ) on wafers cut with green light, potentially affecting the chip surface and significantly reducing wafer cutting yield. Therefore, the development of laser protective fluids specifically designed to absorb green light is imperative. Furthermore, the application of protective fluids that absorb green light should not be limited to laser cutting processes. Plasma cutting also requires laser grooving before plasma cutting. This requires that the plasma cutting protective fluid be applied to the chip surface to form a water-soluble protective mask of a certain thickness, which can simultaneously protect the Low-K layer on the chip surface during laser grooving and plasma cutting, effectively protecting the chip surface from plasma etching.

[0036] An embodiment of the present application provides a protective liquid for green light cutting, which includes the following components, in parts by mass: 20-40 parts of a water-soluble resin, 0.25-0.5 parts of a green light absorber, and 50-100 parts of a solvent; wherein the water-soluble resin includes a water-soluble polyester and sodium polystyrene sulfonate; and the green light absorber includes allura red and lac acid.

[0037] It is understood that the water-soluble resin of this application, which uses a combination of water-soluble polyester and sodium polystyrene sulfonate, is not easily etched and has a high etching selectivity, allowing the desired etching depth of the substrate to be achieved with minimal loss of the protective film layer. The high solubility of sodium polystyrene sulfonate helps increase the resin solid content, increase the film thickness, and improve the stability of the protective solution. In addition, the green light absorber, which uses a combination of allura red and lac acid, ensures solution stability and the photostability of the green light absorber. This also increases the absorber dosage and improves absorbance.

[0038] In some embodiments, the present application provides a protective liquid for green light cutting, which includes the following components, in parts by mass: 20-35 parts of a water-soluble resin, 0.25-0.45 parts of a green light absorber, and 60-90 parts of a solvent.

[0039] In some embodiments, the embodiments of the present application provide a protective liquid for green light cutting, which includes the following components, in parts by mass: 20-34 parts of a water-soluble resin, 0.25-0.4 parts of a green light absorber, and 70-85 parts of a solvent.

[0040] In some embodiments, the mass ratio of the water-soluble polyester to the sodium polystyrene sulfonate is (2-5): 1. For example, the mass ratio of the water-soluble polyester to the sodium polystyrene sulfonate can be any one of 2:1, 3:1, 4:1, 5:1, or a range between any two thereof.

[0041] It is understandable that the mass ratio of the water-soluble polyester to sodium polystyrene sulfonate needs to be within the above range. This is because the water-soluble polyester needs to ensure the stability of the film formed by the protective liquid on the one hand, and on the other hand, it also needs to make the film formed by the protective liquid resistant to etching. If the amount of water-soluble polyester is too small, the etching resistance of the protective liquid will decrease; if the content of the water-soluble polyester is too much, the film structure will be unstable and prone to cracking.

[0042] In some embodiments, the glass transition temperature of the water-soluble polyester is 42-58° C. For example, the glass transition temperature can be any one of 42° C., 43° C., 44° C., 45° C., 46° C., 47° C., 48° C., 49° C., 50° C., 51° C., 52° C., 53° C., 54° C., 55° C., 56° C., 57° C., and 58° C., or a range between any two of the values.

[0043] In some embodiments, the glass transition temperature of sodium polystyrene sulfonate is 40-50° C. For example, it can be any one of 40° C., 41° C., 42° C., 43° C., 44° C., 45° C., 46° C., 47° C., 48° C., 49° C., and 50° C., or a range between any two of these values.

[0044] It can be understood that when the glass transition temperature of water-soluble polyester is 42-58°C and the glass transition temperature of sodium polystyrene sulfonate is 40-50°C, a higher glass transition temperature can ensure that the resin has better mechanical properties and thermal stability, the film layer is not easily scratched, and it is not easy to flow into the cutting path due to heat, affecting the plasma or laser cutting process.

[0045] In some embodiments, the number average molecular weight of the water-soluble polyester is 7000-12000, for example, any one of 7000, 8000, 9000, 10000, 11000, and 12000, or a range between any two of these values.

[0046] In some embodiments, the number average molecular weight of sodium polystyrene sulfonate is 3000-4000, for example, any value among 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, or a range between any two values.

[0047] It can be understood that when the molecular weight of the water-soluble polyester in this embodiment is 7000-12000 and the molecular weight of sodium polystyrene sulfonate is 3000-4000, the resin has excellent film-forming properties within this molecular weight range and forms a complete protective film on the surface of the substrate, and a high-thickness protective liquid can be prepared at a low viscosity.

[0048] In some embodiments, the water-soluble polyester is selected from at least one of EW100G, EW100Q, EW210, and EW100D.

[0049] It is understood that the water-soluble polyester is the Skybon EW series of water-soluble saturated polyester resins provided by SK of South Korea. EW100G, EW100Q, EW210, and EW100D represent the models of this series of resins.

[0050] In some embodiments, performance parameters of the products EW100G, EW100Q, EW210, and EW100D are shown in Table 1 below.

[0051] Table 1

[0052]

[0053]

[0054] It is understandable that the water-soluble polyester is preferably EW210. This is because EW210 has a high glass transition temperature and an appropriate number average molecular weight. Therefore, EW210 greatly improves the film-forming properties and service life in the protective liquid, and at the same time can improve the stability of EW210 in the protective liquid.

[0055] In some embodiments, the EW series water-soluble polyester structure contains groups such as benzene rings and ester groups, which have high bond energies. Plasma etching or laser cutting processes are chemical etching, utilizing plasma to chemically react with the etched material to generate volatile gases. The greater the bond energy of the etched material, the less likely it is to break; in other words, the more stable the chemical bond, the less susceptible it is to etching. Therefore, the water-soluble polyester of this embodiment has a high etching selectivity, allowing the desired etching depth of the substrate to be achieved with minimal loss of the protective film layer.

[0056] In some embodiments, sodium polystyrene sulfonate has a high solubility and can cooperate with water-soluble polyester to increase the solid content of the resin, increase the thickness of the film layer, and further improve the stability of the protective liquid. In some embodiments, the mass ratio of allura red and lac acid is (1-4): 1. For example, the mass ratio of allura red and lac acid can be any one of 1: 1, 2: 1, 3: 1, 4: 1 or a range between any two values. It is understandable that the green light absorber adopts a combination of allura red and lac acid. The allura red in the green light absorber has poor light stability, but good stability in solution. The lac acid in the green light absorber has strong light stability, but its stability in solution is weaker than allura red. The use of the two can ensure the stability of the solution and the light stability of the absorber, and at the same time increase the amount of absorber added, increase the absorbance, and control the heat affected zone to a minimum.

[0057] In some embodiments, the lac acid is selected from at least one of lac acid A, lac acid B, lac acid C, and lac acid E. The CAS number of lac acid A is 15979-35-8, the CAS number of lac acid B is 17249-00-2, the CAS number of lac acid C is 23241-56-7, and the CAS number of lac acid E is 14597-16-1.

[0058] In some embodiments, Allura Red is a small molecule, water-soluble electrolyte with the CAS number 25956-17-6. When it comes into contact with water in the coating, it creates a charge difference and also acts as a detergent. Therefore, Allura Red can both absorb light and improve the cleaning effect of the film.

[0059] In some embodiments, the green light absorber is used to absorb light with a wavelength of 500-600 nm.

[0060] In some embodiments, the solvent is selected from any one of water, alcohol, and ether, or any combination thereof. Specifically, the solvent is selected from at least one of deionized water, methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, isobutanol, ethyl ether, methyl ethyl ether, di-n-butyl ether, propylene glycol methyl ether, ethylene glycol propyl ether, and ethylene glycol butyl ether.

[0061] In some embodiments, the solvent is composed of deionized water and ethylene glycol butyl ether, wherein the mass ratio of deionized water to ethylene glycol butyl ether is (30-90):(5-40). For example, the amount of deionized water is 30-90 parts by mass, preferably 40-80 parts by mass, and most preferably 50-75 parts by mass; the amount of ethylene glycol butyl ether is 5-40 parts by mass, preferably 5-30 parts by mass, and most preferably 5-20 parts by mass.

[0062] It is understandable that ethylene glycol butyl ether serves as both a solvent and a film plasticizer, because ethylene glycol butyl ether is an organic solvent, has good compatibility with the resin, and will not remain in the film for a long time, affecting the film etching selectivity.

[0063] In some embodiments, the water-soluble polyester, sodium polystyrene sulfonate and allura red used in the protective solution of this embodiment are all sulfonate systems, which have excellent compatibility and are conducive to forming a uniform and stable film layer.

[0064] In some embodiments, this embodiment further provides a method for preparing a protective liquid for green light cutting, comprising the following steps:

[0065] Weigh 20-40 parts of water-soluble resin, 0.25-0.5 parts of green light absorber and 50-100 parts of solvent respectively;

[0066] Mixing a water-soluble resin, a green light absorber and a solvent, stirring at 40-50° C. and a speed of 200-500 rpm for 1-5 hours to obtain a protective liquid for green light cutting;

[0067] The water-soluble resin includes water-soluble polyester and sodium polystyrene sulfonate; the green light absorber includes allura red and lac acid.

[0068] In some embodiments, the stirring speed may be any one of 200 rpm, 300 rpm, 400 rpm, 500 rpm, or a range between any two of the values.

[0069] In some embodiments, the stirring time can be any one of 1 h, 2 h, 3 h, 4 h, 5 h, or a range between any two values.

[0070] In some embodiments, the present application also provides a method for using a protective liquid for green light cutting, as follows: first clean the wafers of different sizes to be coated; set the spin coating program, add cutting protection material on the wafer, the amount is 10ml / 4 inch, 15ml / 6 inch, 25ml / 8 inch, 35ml / 12 inch, and spin coat at 1000rpm for 2 minutes; after spin coating, proceed to the next cutting process.

[0071] In some embodiments, this embodiment also provides the use of a protective liquid for green light cutting in a semiconductor wafer laser cutting and / or plasma cutting process. The protective liquid for green light cutting of the present application can be used to protect wafers during cutting. It can adapt to various wafer structures and form a protective film on the wafer surface to ensure that the wafer is not scratched by debris during the cutting process, thereby improving the yield of semiconductor products and the efficiency of cutting.

[0072] It should be noted that all raw materials in the examples of the present application can be obtained commercially. Among them, the molecular weight range of the water-soluble resin, that is, the specific molecular weight of the water-soluble resin, does not mean its exact molecular weight, but rather a suitable fluctuation range (for example, the molecular weight can be measured by various viscosity methods).

[0073] Examples 1-7

[0074] A protective liquid for green light cutting is provided. The specific substances and quantities of the components used in Examples 1-7 are shown in Table 2.

[0075] Comparative Example 1

[0076] A protective liquid for green light cutting is provided. Among the specific components, polyvinyl alcohol is used as the water-soluble resin, and no water-soluble polyester is used. See Table 2 for details.

[0077] Comparative Example 2

[0078] A protective liquid for green light cutting is provided. Among the specific components, the water-soluble resin uses water-soluble polyester, but sodium polystyrene sulfonate is not used. See Table 2 for details.

[0079] Comparative Example 3

[0080] A protective liquid for green light cutting is provided. Among the specific components, the green light absorber does not use allura red, but only uses lac acid. See Table 2 for details.

[0081] Comparative Example 4

[0082] A protective liquid for green light cutting is provided. Among the specific components, the green light absorber does not use lac acid, but only uses allura red. See Table 2 for details.

[0083] Table 2

[0084]

[0085]

[0086] The protective solution was prepared according to the specific components and quantities in Table 2. Specifically, the water-soluble resin, green light absorber, and solvent were weighed in parts by mass; each component was added to a mixing container equipped with a stirrer and stirred at 45°C and 300 rpm for 3 hours to obtain a protective solution for green light cutting.

[0087] The absorbance test of the protective solution obtained in Example 1 was performed, and the obtained UV spectrum was shown in FIG. Figure 1 , it can be seen from the spectrum that there are obvious absorption peaks in the range of 500-550nm, including the absorption peak at 532nm, which shows that the protective solution prepared in Example 1 can absorb green light with a wavelength of 532nm.

[0088] The water-soluble polyester EW210 in Example 1 was subjected to infrared testing, and the infrared spectrum obtained was shown in FIG. Figure 2 , it can be seen from the figure that at 1720cm -1 The characteristic peak of ester group is at 1450cm -1 The peak at 4 is the characteristic peak of C=C bond of benzene ring, which proves that there are ester groups and benzene rings in water-soluble polyester.

[0089] See also Figure 3 and Figure 4 , are pictures after silicon wafer cutting using the protective liquids of Example 1 and Comparative Example 3, Figure 3 It can be seen in the figure that after the silicon wafer is cut, the heat-affected zone near the cutting path is small, about 3.45μm; Figure 4 As can be seen in the figure, after the silicon wafer is cut, the heat-affected zone near the cutting path is large, about 10.35 μm. Therefore, the use of the protective liquid provided in this embodiment can reduce the heat-affected zone of the silicon wafer and significantly improve the cutting yield of the wafer.

[0090] Silicon wafer cutting was further performed using the protective solutions of Examples 1-7 and Comparative Examples 1-4. The heat-affected zone size and etching selectivity data obtained are shown in Table 3.

[0091] Among them, the size of the heat-affected zone is obtained by measuring under a microscope after laser cutting (3.5W); the etching selectivity refers to the ratio of the etching rate of the film layer to the substrate (wafer) after plasma cutting, which is obtained by SEM section measurement. The etching selectivity is defined as the ratio of the etching rate of the etched material to the etching rate of another material.

[0092] Table 3

[0093]

[0094]

[0095] As shown in Table 3, the thermal impact of Examples 1-7 is within 5 microns, and the etch selectivity is all above 1:150. Within this range, the thermal impact will not affect the chip and reduce chip yield. The etch selectivity is relatively high, eliminating the risk of missed etching, which would damage the chip and reduce yield.

[0096] However, since comparative example 1 uses polyvinyl alcohol as the water-soluble resin, the etching selectivity is significantly reduced and the size of the heat-affected zone becomes larger; comparative example 2 does not add sodium polystyrene sulfonate, the resin content is insufficient, and the film layer is thin, which causes the film layer to be etched through during etching and the substrate to be etched, resulting in leakage.

[0097] Experimental verification shows that when the amount of mixed green light absorbers exceeds 0.5 parts, or when the amount of a single green light absorber exceeds 0.25 parts, the protective solution tends to become turbid, forming a turbid solution that cannot form a uniform and stable film, making it unsuitable for application as a protective solution on the wafer surface. Comparative Example 3, using only lac acid A as the green light absorber, resulted in a significant increase in the heat-affected zone (HAZ) size and a decrease in etch selectivity. Comparative Example 4, using only allura red as the green light absorber, also resulted in a significant increase in the HAZ size and a decrease in etch selectivity.

[0098] In summary, the use of water-soluble polyester, especially the combination of Skybon EW series water-soluble saturated polyester resin and sodium polystyrene sulfonate provided by South Korea's SK, as a water-soluble resin is not easily etched and has a high etching selectivity; and the addition of a combination of allura red and lactic acid as a green light absorber can not only reduce the size of the heat-affected zone, but also increase the etching selectivity, thereby improving the yield and productivity in the semiconductor manufacturing process.

[0099] The above is a detailed introduction to a protective liquid for green light cutting, its preparation method and use in the present application. Specific examples are used in the present 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 solutions and core ideas of the present application; ordinary technicians in this field should understand that: they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A protective liquid for green light cutting, characterized in that: The composition comprises the following components in parts by mass: 20-40 parts of a water-soluble resin, 0.25-0.5 parts of a green light absorber, and 50-100 parts of a solvent; Wherein, the water-soluble resin includes water-soluble polyester and sodium polystyrene sulfonate; The green light absorbers include allura red and lactic acid.

2. The protective liquid for green light cutting according to claim 1, characterized in that: The mass ratio of the water-soluble polyester to the sodium polystyrene sulfonate is (2-5):

1.

3. The protective liquid for green light cutting according to claim 1, characterized in that: The glass transition temperature of the water-soluble polyester is 42-58° C.; and / or The number average molecular weight of the water-soluble polyester is 7000-12000; and / or The glass transition temperature of the sodium polystyrene sulfonate is 40-50° C.; and / or The number average molecular weight of the sodium polystyrene sulfonate is 3000-4000.

4. The protective liquid for green light cutting according to claim 3, characterized in that: The water-soluble polyester is selected from at least one of EW100G, EW100Q, EW210, and EW100D.

5. The protective liquid for green light cutting according to claim 1, characterized in that: The mass ratio of the allura red to the lac acid is (1-4):

1.

6. The protective liquid for green light cutting according to claim 5, characterized in that: The lac acid is selected from at least one of lac acid A, lac acid B, lac acid C, and lac acid E; or The green light absorber is used to absorb light with a wavelength of 500-600 nm.

7. The protective liquid for green light cutting according to claim 1, characterized in that: The solvent is selected from at least one of deionized water, methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, isobutanol, ethyl ether, methyl ethyl ether, di-n-butyl ether, propylene glycol methyl ether, ethylene glycol propyl ether, and ethylene glycol butyl ether.

8. The protective liquid for green light cutting according to claim 7, characterized in that: The solvent consists of deionized water and ethylene glycol butyl ether; wherein the mass ratio of the deionized water to the ethylene glycol butyl ether is (30-90):(5-40).

9. A method for preparing a protective liquid for green light cutting, characterized in that: The following steps are involved: Weigh 20-40 parts of water-soluble resin, 0.25-0.5 parts of green light absorber and 50-100 parts of solvent respectively; Mix the water-soluble resin, green light absorber and solvent, and stir at 40-50° C. and 200-500 rpm for 1-5 hours to obtain a protective solution for green light cutting; The water-soluble resin includes water-soluble polyester and sodium polystyrene sulfonate; and the green light absorber includes allura red and lac acid.

10. Use of the protective liquid for green light cutting according to any one of claims 1 to 8 in semiconductor wafer laser cutting and / or plasma cutting processes.

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