Plasma cutting protective fluid and preparation method, application and use method

Abstract

The present application discloses a plasma cutting protection fluid and its preparation method, application, and use method. The plasma cutting protection fluid comprises the following components, by mass: 10-20 parts of a water-soluble resin, 0.3-1 parts of a UV absorber, 20-30 parts of an organic solvent, 0.5-1 parts of a corrosion inhibitor, 2-4 parts of an auxiliary agent, and 30-50 parts of ultrapure water. (E)-2-styryl-1H-phenanthro[9,10-d]imidazole is synthesized using 1,10-o-phenanthroline-5,6-diketone and cinnamaldehyde as raw materials. (E)-2-styryl-1H-phenanthro[9,10-d]imidazole is added to the plasma cutting fluid formula as a small molecule corrosion inhibitor. The prepared protection fluid, after spraying into a film, can form a uniform and complete coverage of the wafer and the surface bumps or grooves without corroding the metal on the wafer surface.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor packaging technology, and specifically relates to a plasma cutting protective liquid and its preparation method, purpose and use method. Background Art

[0002] Plasma cutting is a processing technology that performs dry etching under vacuum to chip (single-wafer) the wafer. It can achieve high-speed, high-aspect-ratio, and narrow-cut chip formation. Therefore, the demand for protective fluids suitable for plasma cutting will also increase. The widely used plasma cutting protective fluid is mainly suitable for spin coating processes and cannot effectively protect the high bumps on the wafer surface. Therefore, it is necessary to develop a plasma cutting protective fluid suitable for ultrasonic spraying processes. However, after ultrasonic spraying, metal corrosion problems are often found on the wafer surface, which brings great hidden dangers to the application of plasma cutting protective fluids. Summary of the Invention

[0003] Purpose of application: This application provides a plasma cutting protective liquid with strong material compatibility and no corrosion to the metal on the wafer surface, as well as its preparation method, purpose and use method.

[0004] Technical solution: The present application provides a plasma cutting protection liquid, which comprises the following components, calculated by weight: 10-20 parts of a water-soluble resin, 0.3-1 parts of a UV absorber, 20-30 parts of an organic solvent, 0.5-1 parts of a corrosion inhibitor, 2-4 parts of an additive, and 30-50 parts of ultrapure water;

[0005] Wherein, the structure of the corrosion inhibitor is shown in the following formula:

[0006]

[0007] In some embodiments, the water-soluble resin is selected from at least one of poly (N-vinylacetamide), polyvinyl pyrrolidone, poly (2-ethyl-2-oxazoline), sodium polystyrene sulfonate, polyethylene glycol, and polymaleic anhydride; and / or

[0008] The number average molecular weight of the water-soluble resin is 10,000-30,000.

[0009] In some embodiments, the ultraviolet absorber is selected from at least one of 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, phenyl o-hydroxybenzoate, hexamethylphosphoric triamide, and resorcinol monobenzoate.

[0010] In some embodiments, the auxiliary agent is selected from at least one of ethylene glycol, propylene glycol, dodecyl alcohol ester, propylene glycol ethyl ether, propylene glycol butyl ether, and ethylene glycol butyl ether acetate.

[0011] In some embodiments, the organic solvent is selected from at least one of methanol, ethanol, glycerol, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, acetone, propylene glycol methyl ether, isopropyl alcohol, and propylene glycol methyl ether acetate.

[0012] In some embodiments, the present application further provides a method for preparing a plasma cutting protective liquid, comprising the following steps:

[0013] Weigh 10-20 parts of water-soluble resin, 0.3-1 parts of UV absorber, 20-30 parts of organic solvent, 0.5-1 parts of corrosion inhibitor, 2-4 parts of additive and 30-50 parts of ultrapure water respectively;

[0014] The corrosion inhibitor is dissolved in an organic solvent to obtain a mixed solution, and then the ultraviolet absorber, additives and ultrapure water are added to the mixed solution and stirred until the materials are completely dissolved. Then, the water-soluble resin is added and stirred again until the mixture is uniform and transparent, and filtered to obtain the plasma cutting protection liquid;

[0015] Wherein, the structure of the corrosion inhibitor is shown in the following formula:

[0016]

[0017] In some embodiments, the method for preparing the corrosion inhibitor further comprises:

[0018] Mixing 1,10-phenanthroline-5,6-dione, cinnamaldehyde and ammonium acetate until completely dissolved, and heating to react to obtain a mixed solution;

[0019] After the mixed solution is cooled, ammonia water is added to adjust the pH of the solution to neutral, so that solid is precipitated, which is then filtered and washed to obtain the corrosion inhibitor.

[0020] In some embodiments, the mass ratio of the 1,10-phenanthroline-5,6-dione, the cinnamaldehyde and the ammonium acetate is 1-1.2:1.1-1.5:18-22;

[0021] The temperature of the temperature-raising reaction is 100-150° C., and the time of the temperature-raising reaction is 2-5 hours.

[0022] In some embodiments, the present application also provides an application of a plasma cutting protection liquid in ultrasonic spraying.

[0023] In some embodiments, the present application further provides a method for using a plasma cutting protective fluid, comprising:

[0024] Spraying a plasma cutting protection liquid on the surface of the wafer by ultrasonic spraying to form a protective film, wherein the protective film is used to cover the bumps and / or grooves on the surface of the wafer;

[0025] The wafer covered with the protective film is plasma cut and cleaned to obtain semiconductor chips.

[0026] Beneficial effects: The plasma cutting protection liquid of the present application comprises the following components, in parts by mass: 10-20 parts of a water-soluble resin, 0.3-1 parts of a UV absorber, 20-30 parts of an organic solvent, 0.5-1 parts of a corrosion inhibitor, 2-4 parts of an additive, and 30-50 parts of ultrapure water. The present application synthesizes (E)-2-phenylvinyl-1H-phenanthro[9,10-d]imidazole using 1,10-phenanthroline-5,6-dione and cinnamaldehyde as raw materials, and adds it to the formula of the plasma cutting liquid as a small molecule corrosion inhibitor. After the prepared protection liquid is sprayed into a film, it can form a uniform and complete coverage on the wafer and the surface bumps or grooves, and will not cause corrosion problems to the metal on the wafer surface.

[0027] It can be understood that the preparation method, application and use method of the plasma cutting protection liquid provided in the embodiments of the present application have all the technical features and beneficial effects of the above-mentioned plasma cutting protection liquid, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] Figure 1 1H NMR spectrum of the corrosion inhibitor provided in the examples of the present application;

[0030] Figure 2 This is an OM image of the wafer surface after the corrosion resistance test using the protective solution of Example 1, magnified 100 times;

[0031] Figure 3 This is an OM image of the wafer surface after the corrosion resistance test using the protective solution of Comparative Example 1, magnified 100 times;

[0032] Figure 4 This is an optical microscope (OM) image of the surface of the Dummy sheet after cleaning and spraying the protective solution of Example 1 for high temperature resistance test, with a magnification of 200 times;

[0033] Figure 5 This is an optical microscope (OM) image of the surface of the Dummy sheet after cleaning, which was sprayed with the protective liquid of Comparative Example 1 for high temperature resistance test, with a magnification of 200 times;

[0034] Figure 6 This is an SEM image of the wafer surface after plasma dicing after spraying the protective liquid of Example 1, with a magnification of 350 times;

[0035] Figure 7 This is a SEM image of the wafer surface after plasma dicing after spraying the protective liquid of Comparative Example 1, with a magnification of 350 times. DETAILED DESCRIPTION

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Plasma dicing is a process that uses dry etching under vacuum to create wafer chips (single-wafers). This technology enables high-speed, high-aspect-ratio, and narrow-slice dicing. In the processing of artificial intelligence, discrete components, and radio frequency identification (RFID) chips, the trend toward narrower dicing lanes is increasing to increase the number of chips that can be obtained per wafer. Overall, plasma dicing offers several advantages over traditional laser dicing, including increased productivity for small chip components, compatibility with a variety of processing shapes, a highly clean process, and improved chip strength.

[0040] With the rapid development of semiconductor packaging and increasingly stringent process requirements, plasma cutting applications are becoming increasingly widespread, leading to a growing demand for protective fluids suitable for plasma cutting. Previously, the plasma cutting protective fluids widely used in the market were primarily suitable for spin coating processes, which were unable to effectively protect the bumps and grooves on the wafer surface. These technical challenges necessitated the use of ultrasonic spraying. However, during the development of ultrasonic spraying plasma protective fluids, varying degrees of corrosion on the metal surface of the wafer were often observed, posing a significant risk to their future application.

[0041] Based on this, the embodiments of the present application provide a safe, environmentally friendly, efficient and suitable ultrasonic spray protective liquid for plasma cutting and its preparation method. A uniform and dense film layer can be obtained through ultrasonic spraying, which can achieve uniform coverage of wafers and surface bumps, grooves and other structures without causing any corrosion problems to the metal on the wafer surface. It can be used in advanced packaging grinding and scratching processes.

[0042] The present application provides a plasma cutting protection liquid, which comprises the following components, in parts by mass: 10-20 parts of a water-soluble resin, 0.3-1 parts of a UV absorber, 20-30 parts of an organic solvent, 0.5-1 parts of a corrosion inhibitor, 2-4 parts of an additive, and 30-50 parts of ultrapure water;

[0043] Wherein, the structure of the corrosion inhibitor is shown in the following formula:

[0044]

[0045] It is understood that the above corrosion inhibitor is synthesized from 1,10-phenanthroline-5,6-dione and cinnamaldehyde to synthesize (E)-2-phenylvinyl-1H-phenanthro[9,10-d]imidazole. Among them, the CAS number of 1,10-phenanthroline-5,6-dione is 27318-90-7, and the molecular formula is C 12 H6N2O2, molecular weight is 210.188; CAS number of cinnamaldehyde is 104-55-2, molecular formula is C9H8O, molecular weight is 132.159.

[0046] The structure of the corrosion inhibitor of the present application contains a large number of N atoms and unsaturated bonds, which can form a dense film on the surface of the wafer by physical adsorption or coordination bond, so as to achieve uniform coverage of the bumps or grooves on the surface of the wafer, and at the same time, it can isolate the penetration of corrosive media such as water vapor and oxygen, and improve the corrosion resistance of the metal on the surface of the wafer. In addition, an aromatic ring is introduced into the structure to further improve the conjugation ability of the molecule, promote the π electron to undergo π→π transition, thereby improving the ultraviolet absorption capacity; At the same time, thanks to its own conjugated system and chemical bond structure, since the double bond is located between the aromatic ring and the imidazole structure, the synergistic structure of the aromatic ring and the double bond jointly gives the corrosion inhibitor molecule high heat resistance, thereby improving the cleanability of the film layer after plasma cutting. The protective liquid containing the above-mentioned structure corrosion inhibitor can simultaneously have multiple characteristics such as high corrosion resistance, good temperature resistance, strong ultraviolet absorption capacity, and excellent water cleaning properties during ultrasonic spray plasma cutting.

[0047] Furthermore, cinnamaldehyde is used as a raw material for synthesis because it has a trans structure. When it is introduced into the molecular structure of the corrosion inhibitor, the double bonds in the trans structure can make the molecules more compact and improve the antioxidant effect, thereby further reducing the corrosion of the cutting protection liquid on the metal on the wafer surface.

[0048] It can be understood that the plasma cutting protection liquid of the present application uses the substance shown in the above formula as a corrosion inhibitor, and a uniform and dense film layer can be obtained through ultrasonic spraying, which can achieve uniform coverage of wafers and surface bumps (Bumps), grooves and other structures without corrosion, and can be used in advanced packaging grinding processes.

[0049] In some embodiments, the water-soluble resin is selected from at least one of poly(N-vinylacetamide), poly(vinylpyrrolidone), poly(2-ethyl-2-oxazoline), sodium polystyrene sulfonate, polyethylene glycol, and polymaleic anhydride. Poly(N-vinylacetamide) is prepared by polymerizing N-vinylacetamide (CAS No. 5202-78-8); poly(vinylpyrrolidone) has a CAS No. 9003-39-8; poly(2-ethyl-2-oxazoline) has a CAS No. 25805-17-8; sodium polystyrene sulfonate has a CAS No. 25704-18-1; polyethylene glycol has a CAS No. 25322-68-3; and polymaleic anhydride has a CAS No. 24937-72-2. The water-soluble resin has excellent solubility and is used to form a protective coating on the surface of the wafer to prevent oxidation and corrosion during the cutting process. In addition, the water-soluble resin can also adhere to the wafer surface to improve the adhesion of the coating on the cutting surface. The film layer formed can prevent the intrusion of oxygen and other harmful substances, and can absorb part of the laser energy to reduce melting and burning of the cutting surface.

[0050] In some embodiments, the number average molecular weight of the water-soluble resin is 10,000-30,000. For example, the number average molecular weight can be any one of 10,000, 15,000, 20,000, 25,000, and 30,000, or a range between any two values. Using a water-soluble resin with such a number average molecular weight, a moderate and uniform film can be formed at a low resin content, without surface cracking, bubbles, or coating leaks, and complete coverage of bumps and grooves on the wafer surface.

[0051] In some embodiments, the UV absorber is selected from at least one of 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, phenyl o-hydroxybenzoate, hexamethylphosphoric acid triamide, and resorcinol monobenzoate. The UV absorber enhances the protective film's absorption of UV light, preventing laser damage to the edges of the cut lanes during the laser grooving process or scattered laser light from damaging other areas. Among them, the CAS number of 2,4-dihydroxybenzophenone is 131-56-6; 2-hydroxy-4-methoxybenzophenone is ultraviolet absorber UV-9, with a CAS number of 131-57-7; the CAS number of 2-hydroxy-4-n-octyloxybenzophenone is 1843-05-6; the CAS number of phenyl o-hydroxybenzoate is 118-55-8; the CAS number of hexamethylphosphoric triamide is 680-31-9; and the CAS number of resorcinol monobenzoate is 136-36-7.

[0052] In some embodiments, the auxiliary agent is selected from at least one of ethylene glycol, propylene glycol, dodecyl alcohol ester, propylene glycol ethyl ether, propylene glycol butyl ether, and ethylene glycol butyl ether acetate. The introduction of ethylene glycol butyl ether acetate as an auxiliary agent is intended to improve the wettability of the protective liquid on the wafer surface, further improve the adhesion of the protective liquid film layer on the metal structure by increasing the spreading of the liquid film on the wafer surface, and enhance the spraying effect. The auxiliary agent can improve the wettability of the protective liquid on the metal surface. This is because the wetting effect affects the adhesion. In order to achieve good adhesion between the film layer molecules and the metal on the wafer, the protective liquid must first be able to spread spontaneously on the metal. If there is no contact between the molecules, there will be no interaction, and there will be no promoting effect on the adhesion. Therefore, the auxiliary agent is an important factor in generating interaction.

[0053] In some embodiments, the organic solvent is selected from at least one of methanol, ethanol, glycerol, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, acetone, propylene glycol methyl ether, isopropyl alcohol, and propylene glycol methyl ether acetate.

[0054] In some embodiments, the present application further provides a method for preparing a plasma cutting protective liquid, comprising the following steps:

[0055] Weigh 10-20 parts of water-soluble resin, 0.3-1 parts of UV absorber, 20-30 parts of organic solvent, 0.5-1 parts of corrosion inhibitor, 2-4 parts of additive and 30-50 parts of ultrapure water respectively;

[0056] The corrosion inhibitor is dissolved in an organic solvent to obtain a mixed solution, and then the ultraviolet absorber, additives and ultrapure water are added to the mixed solution and stirred until the materials are completely dissolved. Then, the water-soluble resin is added and stirred again until the mixture is uniform and transparent, and filtered to obtain the plasma cutting protection liquid;

[0057] The structure of the corrosion inhibitor is shown below:

[0058]

[0059] In the method of the present application, (E)-2-phenylvinyl-1H-phenanthro[9,10-d]imidazole was synthesized using 1,10-phenanthroline-5,6-dione and cinnamaldehyde as raw materials, and added to the formula as a small molecule corrosion inhibitor. After the protective liquid is sprayed into a film, it can form a uniform and complete coverage of the wafer and the surface bumps without causing corrosion problems to the metal on the wafer surface.

[0060] In some embodiments, the specific preparation process of the above-mentioned plasma cutting protection liquid is: first weigh each component material in its respective amount; then dissolve the corrosion inhibitor in an organic solvent to obtain a mixed solution, and then add the other components (including the mixed solution) except the water-soluble resin into the container in sequence, start stirring, and add the water-soluble resin of all components after the material is completely dissolved, stir until it is uniform and transparent, and then filter with a 0.1μm filter element to obtain the semiconductor chip ultrasonic spray plasma cutting protection liquid.

[0061] In some embodiments, the preparation method of the corrosion inhibitor further includes: mixing 1,10-phenanthroline-5,6-dione, cinnamaldehyde and ammonium acetate until completely dissolved, heating the mixture to react to obtain a mixed solution; after the mixed solution is cooled, ammonia water is added to adjust the pH of the solution to neutral to obtain a solid precipitate, which is then filtered and washed to obtain the corrosion inhibitor.

[0062] In some embodiments, the mass ratio of 1,10-phenanthroline-5,6-dione, cinnamaldehyde, and ammonium acetate is 1-1.2:1.1-1.5:18-22. For example, the mass ratio can be any one of 1:1.1:18, 1.1:1.2:20, 1.2:1.5:22, 1.1:1.5:18, and 1.2:1.1:19.

[0063] In some embodiments, the temperature of the elevated temperature reaction is 100-150° C. For example, it can be any one of 100° C., 110° C., 120° C., 130° C., 140° C., and 150° C., or a range between any two of these values.

[0064] In some embodiments, the temperature-elevated reaction time is 2 to 5 hours, for example, any one of 2 hours, 3 hours, 4 hours, and 5 hours, or a range between any two of these values.

[0065] Specifically: the corrosion inhibitor is synthesized using 1,10-phenanthroline-5,6-dione and cinnamaldehyde as raw materials, and the synthesis method is as follows:

[0066] First, a fixed ratio of 1,10-phenanthroline-5,6-dione, cinnamaldehyde, and ammonium acetate was dissolved in 30 mL of glacial acetic acid. A condensation reflux apparatus was set up, stirring was started, and the temperature was raised to 100 ° C until the mixed solution was completely dissolved. Then the temperature was continued to rise to 120 ° C for 3 hours of condensation reflux. After the reaction was completed, it was naturally cooled to room temperature. The resulting solution was diluted with deionized water and the pH value was adjusted to neutral with concentrated ammonia water. A large amount of light yellow solid was precipitated. After filtration, the filter cake was repeatedly washed with deionized water several times, and then dried in a vacuum drying oven at 80 ° C to obtain the pure product. The synthesis route is as follows:

[0067]

[0068] In some embodiments, the present application also provides an application of a plasma cutting protection fluid in ultrasonic spraying. The provided plasma protection fluid for ultrasonic spraying of semiconductor chips can achieve uniform coverage of the wafer, as well as surface bumps and grooves, effectively preventing the effects of silicon slag and plasma gas on the wafer, thereby improving cutting yield and productivity.

[0069] In some embodiments, a method for using a protective liquid for ultrasonic spraying plasma cutting of semiconductor chips is provided, comprising the following steps:

[0070] Ultrasonic spraying is used to spray plasma cutting protection liquid on the surface of the wafer to form a protective film, which is used to cover the bumps and / or grooves on the surface of the wafer;

[0071] The wafer covered with the protective film is plasma cut and cleaned to obtain semiconductor chips.

[0072] The specific process is:

[0073] Step 1: Use the semiconductor chip ultrasonic spray plasma cutting protection liquid as the stock solution;

[0074] Step 2: Select a wide-width nozzle, set the spraying mode to fan-shaped area, spray operating frequency to 50kHz, adjust the flow rate to 1mL / min, fix the distance between the nozzle and the wafer to 70mm, spray 5 times, and set the heating stage temperature to 60℃;

[0075] Step 3: The 8-inch wafer covered with the protective film is laser grooved using a 2-8W power energy beam, followed by a plasma cutting process;

[0076] Step 4: The plasma-cut wafer is cleaned with ultrapure water to complete the plasma cutting operation.

[0077] It is understandable that the plasma cutting protection liquid of the present application can be used for ultrasonic spraying. Ultrasonic spraying is a spraying method based on ultrasonic atomization technology, which has higher uniformity and precision than spin coating. First, the coating material to be deposited is formulated into a liquid such as a solution, sol or suspension, and then these liquids are atomized into micron-sized droplets through a special ultrasonic atomization device called an ultrasonic nozzle. These tiny droplets are then evenly deposited on the surface of the substrate through a certain amount of carrier gas, thereby forming a thin film coating. Because the atomized particles are fine and the particle surface activity is high, the small droplet particles can adhere well to the wafer surface.

[0078] In some embodiments, ultrapure water is deionized water with a resistance of ≥18 MΩ.

[0079] It should be noted that all raw materials in the examples of the present application can be obtained commercially. Among them, the molecular weight of the water-soluble resin satisfies the range of 10,000-30,000. The specific molecular weight of the water-soluble resin does not mean its exact molecular weight, but rather a variation within a suitable upper and lower fluctuation range (for example, the molecular weight can be determined by various viscosity methods).

[0080] Examples 1-6

[0081] A plasma cutting protection liquid is provided. The specific substances and quantities of the components used in Examples 1-6 are shown in Table 1.

[0082] The specific preparation process is as follows: first, weigh each component material in its respective amount; then, dissolve the corrosion inhibitor in an organic solvent to obtain a mixed solution; then, add the other components (including the mixed solution) except the water-soluble resin into the container in sequence, start stirring, and add the water-soluble resin of all components until the material is completely dissolved; stir until uniform and transparent; and finally filter with a 0.1μm filter element to obtain the semiconductor chip ultrasonic spray plasma protective liquid.

[0083] The corrosion inhibitor in Example 1-6 is (E)-2-phenylvinyl-1H-phenanthro[9,10-d]imidazole, and its structure is shown below:

[0084]

[0085] In this embodiment, the specific preparation method of the corrosion inhibitor is:

[0086] First, 1,10-phenanthroline-5,6-dione, cinnamaldehyde, and ammonium acetate were dissolved in 30 mL of glacial acetic acid at a mass ratio of 1:1.1:20. A reflux apparatus was set up, stirring was initiated, and the mixture was heated to 100°C until it was completely dissolved. The temperature was then raised to 120°C for 3 hours of reflux. After the reaction was complete, the mixture was naturally cooled to room temperature. The resulting solution was diluted with deionized water and the pH was adjusted to neutral with concentrated ammonia. A large amount of pale yellow solid precipitated. The filter cake was filtered, washed repeatedly with deionized water, and then dried in a vacuum oven at 80°C to obtain the pure product.

[0087] See further Figure 1 The 1H NMR spectrum of the obtained (E)-2-phenylvinyl-1H-phenanthro[9,10-d]imidazole is shown below:

[0088]

[0089] In the 1H NMR spectrum, the peaks at δ:7.39-8.80 are attributed to the 11 hydrogens on the benzene ring (a, b, c, g, h, i and their symmetrical positions), the peaks at δ:6.95 and 6.99 are attributed to the two hydrogens at the double bond (e, f) positions in the molecular structure, and the peak at δ:12.54 is attributed to one hydrogen on the imidazole ring (d).

[0090] Table 1

[0091]

[0092]

[0093] Comparative Example 1

[0094] A plasma cutting protection fluid is provided, which differs from Example 1 in that it does not contain the corrosion inhibitor used in Example 1. The specific components include: 15 parts of a water-soluble resin poly (N-vinylacetamide) with a molecular weight of 20,000; 0.6 parts of a UV absorber 2,4-dihydroxybenzophenone; 3 parts of an additive ethylene glycol butyl ether acetate; 25 parts of an organic solvent isopropyl alcohol; and 40 parts of ultrapure water.

[0095] Comparative Example 2

[0096] A plasma cutting protection fluid is provided, which differs from Example 1 in that the corrosion inhibitor used is commercially available benzimidazole. The fluid comprises: 15 parts of a water-soluble resin (poly(N-vinylacetamide) with a molecular weight of 20,000); 0.6 parts of a UV absorber (2,4-dihydroxybenzophenone); 0.8 parts of a corrosion inhibitor (benzimidazole); 3 parts of an additive (ethylene glycol butyl ether acetate); 25 parts of an organic solvent (isopropyl alcohol); and 40 parts of ultrapure water. Benzimidazole does not contain a large number of nitrogen atoms and lacks the synergistic structure of double bonds and benzene rings.

[0097] The plasma cutting protection fluids of Examples 1-6 and Comparative Examples 1-2 were tested for corrosion resistance, high temperature resistance, and protection degree, respectively. The test results are shown in Table 2.

[0098] Among them, the test method for corrosion resistance is:

[0099] Wafers of equal size were split and immersed in 50 mL of ultrasonic spray plasma protective solution for 4, 8, 12, 24, 48, and 36 hours. The wafer surface was then observed under a microscope. Poor corrosion resistance means obvious corrosion damage is observed under OM after immersion; good corrosion resistance means no obvious abnormalities under OM after immersion.

[0100] The test method for high temperature resistance is:

[0101] A bare Si wafer was ultrasonically sprayed. After the film was completely dry, it was placed on a heating plate and baked at 300°C for 30 minutes. The wafer was then cleaned with a second fluid and dried, and the surface of the dummy wafer was observed under a microscope. Poor high-temperature resistance means that the second fluid cannot completely clean the film after baking; good high-temperature resistance means that the second fluid can completely clean the film after baking.

[0102] The test method for the degree of protection is:

[0103] The full plasma dicing process was verified on wafers. The top of the wafer was observed using a scanning electron microscope before and after cleaning. The wafers were 8 inches in size and had Cu pillars and Sn balls on their surfaces. Incomplete protection means the film layer fails to completely cover the bump tops or sidewalls; good protection means the film layer completely covers the bump tops or sidewalls.

[0104] Table 2

[0105] Corrosion resistance High temperature resistance (cleanability) Degree of protection Example 1 good good good Example 2 good good good Example 3 good good good Example 4 good good good Example 5 good good good Example 6 good good good Comparative Example 1 Difference Difference Not fully protected Comparative Example 2 Difference Difference Not fully protected

[0106] As can be seen from Table 2, the use of the plasma cutting protection liquid of Examples 1-6 of the present application can avoid the problem of corrosion of the metal on the wafer surface, and does not affect the morphology of the wafer surface at high temperatures, has excellent high temperature resistance, and can well protect the structure of the wafer surface after plasma cutting. Therefore, the plasma cutting protection liquid of this embodiment can form a uniform and complete coverage of the wafer and surface bumps, grooves, etc., and will not cause corrosion problems to the metal on the wafer surface. At the same time, the high heat resistance also improves the cleanability of the film layer after plasma cutting. In Comparative Examples 1-2, since the corrosion inhibitor of this embodiment is not used, the corrosion resistance, high temperature resistance and degree of protection of the wafer of the plasma cutting protection liquid are reduced, and cannot meet the cutting requirements.

[0107] See further Figure 2 and Figure 3 , respectively, are OM images of the wafer surface after corrosion resistance tests using the protective solutions provided in Example 1 and Comparative Example 1 of the present application. As can be seen from the figures, the wafer surface in Comparative Example 1 exhibits significant corrosion after the corrosion resistance test, while the wafer surface in Example 1 remains smooth and free of any abnormalities. This demonstrates that the addition of the corrosion inhibitor in this example helps improve the corrosion resistance of the plasma cutting protective solution.

[0108] See further Figure 4 and Figure 5 , respectively, show the surface OM images of the dummy sheets after cleaning after spraying the protective fluids of Example 1 and Comparative Example 1 for high-temperature resistance testing. As can be seen from the images, a large area of ​​film remains on the surface of the dummy sheet of Comparative Example 1 after cleaning during the high-temperature performance test, while the surface of the dummy sheet of Example 1 is highly clean with no obvious abnormalities. This demonstrates that the addition of the corrosion inhibitor of this example helps improve the high-temperature resistance of the plasma cutting protective fluid.

[0109] See further Figure 6 and Figure 7 , respectively, are SEM images of Example 1 and Comparative Example 1 after plasma dicing with the protective solution. As can be seen in Comparative Example 1, after plasma dicing, no film remains on the top of the bump, posing a risk of damage. In contrast, Example 1 maintains relatively complete film coverage on the top of the bump after plasma dicing, demonstrating excellent protective performance.

[0110] The above is a detailed introduction to the plasma cutting protective liquid and its preparation method, application and use method 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 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 make equivalent replacements for some of the technical features therein; 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 this application.

Claims

1. A plasma cutting protective liquid, characterized in that: The invention comprises the following components in parts by mass: 10-20 parts of a water-soluble resin, 0.3-1 parts of an ultraviolet absorber, 20-30 parts of an organic solvent, 0.5-1 parts of a corrosion inhibitor, 2-4 parts of an auxiliary agent and 30-50 parts of ultrapure water; Wherein, the structure of the corrosion inhibitor is shown in the following formula:

2. The plasma cutting protection liquid according to claim 1, characterized in that: The water-soluble resin is at least one selected from poly (N-vinylacetamide), polyvinylpyrrolidone, poly (2-ethyl-2-oxazoline), sodium polystyrene sulfonate, polyethylene glycol, and polymaleic anhydride; and / or The number average molecular weight of the water-soluble resin is 10,000-30,000.

3. The plasma cutting protection liquid according to claim 1, characterized in that: The ultraviolet absorber is selected from at least one of 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, phenyl o-hydroxybenzoate, hexamethylphosphoric triamide, and resorcinol monobenzoate.

4. The plasma cutting protection liquid according to claim 1, characterized in that: The auxiliary agent is selected from at least one of ethylene glycol, propylene glycol, dodecyl alcohol ester, propylene glycol ethyl ether, propylene glycol butyl ether, and ethylene glycol butyl ether acetate.

5. The plasma cutting protection liquid according to claim 1, characterized in that: The organic solvent is selected from at least one of methanol, ethanol, glycerol, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, acetone, propylene glycol methyl ether, isopropyl alcohol, and propylene glycol methyl ether acetate.

6. A method for preparing a plasma cutting protective liquid, characterized in that: The following steps are involved: Weigh 10-20 parts of water-soluble resin, 0.3-1 parts of UV absorber, 20-30 parts of organic solvent, 0.5-1 parts of corrosion inhibitor, 2-4 parts of additive and 30-50 parts of ultrapure water respectively; The corrosion inhibitor is dissolved in an organic solvent to obtain a mixed solution, and then the ultraviolet absorber, additives and ultrapure water are added to the mixed solution and stirred until the materials are completely dissolved. Then, the water-soluble resin is added and stirred again until the mixture is uniform and transparent, and filtered to obtain the plasma cutting protection liquid; Wherein, the structure of the corrosion inhibitor is shown in the following formula:

7. The method for preparing a plasma cutting protection liquid according to claim 6, characterized in that: The preparation method of the corrosion inhibitor further comprises: Mixing 1,10-phenanthroline-5,6-dione, cinnamaldehyde and ammonium acetate until completely dissolved, and heating to react to obtain a mixed solution; After the mixed solution is cooled, ammonia water is added to adjust the pH of the solution to neutral, so that solid is precipitated, which is then filtered and washed to obtain the corrosion inhibitor.

8. The method for preparing a plasma cutting protection liquid according to claim 7, characterized in that: The mass ratio of the 1,10-phenanthroline-5,6-dione, the cinnamaldehyde and the ammonium acetate is 1-1.2:1.1-1.5:18-22; The temperature of the temperature-raising reaction is 100-150° C., and the time of the temperature-raising reaction is 2-5 hours.

9. Application of plasma cutting protection liquid in ultrasonic spraying, characterized in that: The plasma cutting protection liquid is the plasma cutting protection liquid according to any one of claims 1 to 5; or, the plasma cutting protection liquid is prepared by the method according to any one of claims 6 to 8.

10. A method for using the plasma cutting protection liquid according to any one of claims 1 to 5, characterized in that: include: Spraying a plasma cutting protection liquid on the surface of the wafer by ultrasonic spraying to form a protective film, wherein the protective film is used to cover the bumps and / or grooves on the surface of the wafer; The wafer covered with the protective film is plasma cut and cleaned to obtain semiconductor chips.

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