Polyester resin, plasma cutting protection liquid, preparation method and use method

Abstract

The invention provides polyester resin, plasma cutting protection liquid, a preparation method and a use method. The polyester resin has a structure as shown in a formula I in the specification. The plasma cutting protection liquid provided by the invention is good in stability, good in coating effect, easy to wash, high in etching resistance and narrow in heat affected zone.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor manufacturing technology, and specifically relates to a polyester resin, a plasma cutting protection liquid, a preparation method and a use method, in particular to a water-soluble polyester resin with UV absorption function, a preparation method, a plasma cutting protection liquid, a preparation method and a use method. Background Art

[0002] With the increasing integration and sophistication of the semiconductor industry, the density of grains on wafers has gradually increased, and the width of etched paths has gradually decreased. Compared with traditional wheel cutting and laser cutting, plasma cutting processes can meet the cutting requirements of rapidly developing chips. Plasma cutting protective fluids must have certain UV absorption and heat resistance to ensure the formation of a well-formed mask during the etching process. During the etching process, the protective film must be chemically stable to the etchant and have a certain thickness to withstand the anisotropic ion bombardment of the plasma. After the plasma etching is completed, the protective film must be washed. Therefore, the resin used in the protective film must ensure that it will not excessively cross-link during the high temperature of the plasma etching process, which would affect the water washability of the protective film.

[0003] To meet the process requirements for plasma cutting protective fluids, researchers have conducted extensive research and achieved certain results. For example, CN 118772722 A discloses a method for preparing a plasma cutting protective fluid and its application in a process. The plasma cutting protective fluid comprises a water-soluble polyvinylamine resin or polyacrylamide resin, a water-soluble UV absorber, and a cleaning material. The protective fluid and the cleaning material work together to easily remove the protective film formed, reducing particle residue on the chip surface. However, the system contains a large number of components, resulting in poor storage stability.

[0004] CN113710753A discloses a heat-resistant and plasma-resistant water-washable coating protective liquid for laser mutual application, which includes a water-soluble polyester resin, a water-soluble UV absorber, an additive and a solvent. The invention provides the coating with the ability to highly interact with specific lasers, allowing low-energy patterning without damaging the chip, while also providing subsequent resistance to plasma etching. Similarly, due to its large number of system components, the product storage stability is poor.

[0005] CN 119529643 A discloses a method using a combination of water-soluble polyester, sodium polystyrene sulfonate, and a green light absorber to make the mask less susceptible to plasma etching. The etching selectivity is relatively high (approximately 150:1), and the required etching depth of the substrate can be achieved with minimal loss of the protective film. However, the heat-affected zone is too large (>3 μm), making it difficult to meet the requirements of the plasma cutting process.

[0006] Plasma cutting protection fluid is generally composed of a main resin, an external light absorber, and a solvent. The main resin can be polyester resin, but polyester resin does not have UV absorption capacity. Therefore, a UV absorber must be added to the polyester resin to enhance its UV absorption capacity. However, due to the increase in system components, the components may repel each other. For example, polyester resin and UV absorber may repel each other, resulting in insufficient product stability and a relatively limited storage time (usually less than six months). Furthermore, the etching resistance of current plasma cutting protection fluids still needs to be improved, and the heat-affected zone needs to be further reduced.

[0007] Therefore, it is necessary to develop a plasma cutting protective fluid that can be stably stored for more than one year, has strong corrosion resistance and a narrow heat-affected zone. Summary of the Invention

[0008] In view of the shortcomings of the prior art, the present invention provides a polyester resin, a plasma cutting protection fluid, and a preparation method and use method thereof. The plasma cutting protection fluid provided by the present invention has good stability, good coating effect, easy water washing, strong etching resistance, and a narrow heat-affected zone.

[0009] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a polyester resin having a structure shown in the following formula I:

[0011]

[0012] in,

[0013] “UV—” indicates the residue of UV absorber;

[0014] R1 and R3 are each independently selected from the residue of a polycarboxylic acid, the residue of an acid anhydride or the residue of a polycarboxylic acid ester;

[0015] R2 and R4 are each independently selected from the residue of an alkyl diol, the residue of an aromatic diol or the residue of a cycloalkyl diol;

[0016] n is an integer from 20 to 300, for example, 20, 30, 40, 50, 60, 80, 100, 120, 140, 150, 160, 180, 200, 220, 250, 280, 300, etc.

[0017] As the requirements for wafer cutting process become increasingly higher, plasma cutting technology has been introduced into the wafer cutting process. During the plasma cutting process, a layer of plasma cutting protection liquid with UV absorption ability needs to be coated on the wafer surface to achieve the purpose of protecting the chip.

[0018] The polyester resin provided by the present invention has UV absorbing groups. When used in a plasma cutting process, no additional UV light absorber needs to be added. Moreover, since the polyester resin is connected to the UV absorbing groups through a chemical bond, there is no problem of unstable storage performance caused by the mutual repulsion between the two. That is, the polyester resin provided by the present invention has excellent storage stability, and at the same time has relatively excellent high-temperature resistance, good coating effect, easy water washing, a small heat-affected zone and a high selective etching ratio.

[0019] Preferably, the UV absorber is selected from salicylate UV absorbers, benzophenone UV absorbers, benzotriazole UV absorbers or triazine UV absorbers, preferably benzophenone UV absorbers.

[0020] Preferably, the structural formula of the salicylate UV absorber is Y is selected from methyl, ethyl, n-propyl or octyl, preferably octyl.

[0021] Preferably, the benzophenone UV absorber The compound is selected from 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone, and is preferably 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

[0022] Preferably, the benzotriazole UV absorber is selected from UV-326 or UV-327 UV-327 is preferred.

[0023] Preferably, the triazine UV absorber is selected from ethylhexyl triazone, UV-1577, UV-1164 or UV-400 (CAS: 153519-44-9), preferably UV-1577 or UV-400.

[0024] Preferably, R1 and R3 are each independently selected from in:

[0025] X is O, N or S.

[0026] Indicates the group attachment site.

[0027] Preferably, R2 and R4 are each independently selected from

[0028] in: Preferably, the polyester resin is selected from any one of the following resins:

[0029]

[0030]

[0031] Wherein, n is an integer of 20-300, for example, 20, 30, 50, 60, 80, 100, 120, 150, 180, 200, 220, 250, 280, 300, etc., preferably an integer of 20-50.

[0032] Preferably, the weight average molecular weight of the polyester resin is 20,000-200,000, for example, 20,000, 25,000, 30,000, 35,000, 40,000, 450,000, 50,000, 60,000, 80,000, 100,000, 120,000, 140,000, 160,000, 180,000, 200,000, etc., preferably 50,000-100,000.

[0033] The polyester resin provided by the present invention is water-soluble and high-temperature resistant, with a thermal decomposition temperature exceeding 350° C. Furthermore, the molecular weight of the polyester resin provided by the present invention can be controlled by controlling the polymerization time, thereby meeting different viscosity requirements.

[0034] In a second aspect, the present invention provides a method for preparing the polyester resin according to the first aspect, the preparation method comprising:

[0035] reacting a polyester polymer with a UV absorber containing a hydroxyl group to obtain the polyester resin;

[0036] in:

[0037] The structural formula of polyester polymer is

[0038] R1 and R3 are each independently selected from the residue of a polycarboxylic acid, the residue of an acid anhydride or the residue of a polycarboxylic acid ester;

[0039] R2 and R4 are each independently selected from the residue of an alkyl diol, the residue of an aromatic diol or the residue of a cycloalkyl diol;

[0040] n is an integer of 20-300, for example, 20, 30, 50, 60, 80, 100, 120, 150, 180, 200, 220, 250, 280, 300, etc.

[0041] Preferably, the The preparation method of polyester polymer includes:

[0042] The carboxylic acid, anhydride or carboxylate compound with an R1 group, the diol compound with an R2 group, the carboxylic acid, anhydride or carboxylate compound with an R3 group and the diol compound with an R4 group undergo polymerization reaction to obtain the polyester polymer.

[0043] Preferably, the carboxylic acid, anhydride or carboxylate compound with an R1 group, and the carboxylic acid, anhydride or carboxylate compound with an R3 group are independently selected from D-camphoric acid, 1,1-cyclopropanedicarboxylic acid, diethyl 1,1-cyclopropanedicarboxylate, cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,3-adamantanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and other fatty carboxylic acids or fatty acid anhydrides; phthalic acid / phthalic anhydride, isophthalic acid / dimethyl isophthalate, sodium 5-sulfonate of isophthalic acid, dimethyl isophthalate-5-sulfonate, terephthalic acid, dimethyl phthalate, phthalic acid The present invention also includes aromatic carboxylic acids or anhydrides or esters such as diethyl phthalate, dibutyl phthalate, dioctyl phthalate, 3-fluorophthalic acid, and 4-nitrophthalic acid; trivalent aromatic carboxylic acids / esters such as trimesic acid, trimellitic anhydride, pyromellitic dianhydride, pyromellitic acid, 1,2,3-benzenetricarboxylic acid, and 1,2,4-benzenetricarboxylic acid; any one or a combination of at least two of heteroaryl carboxylic acids or esters such as furandicarboxylic acid / dimethyl furandicarboxylate, pyrrole dicarboxylic acid, and thiophenedicarboxylic acid, and more preferably any one or a combination of at least two of D-camphoric acid, 1,1-cyclopropanedicarboxylic acid, dimethyl phthalate, sodium 5-sulfoisophthalate, isophthalic acid, trimellitic anhydride, or dimethyl furandicarboxylate.

[0044] Preferably, R1 and / or R3 contain a sodium sulfonate group. Preferably, at least one of the carboxylic acid, anhydride or carboxylate compound having an R1 group and the carboxylic acid, anhydride or carboxylate compound having an R3 group is selected from compounds having a sodium sulfonate group, preferably sodium 5-sulfoisophthalate.

[0045] Preferably, the diol compound with an R2 group and the diol compound with an R4 group are selected from alkyl diols, cycloalkyl diols or aromatic diols.

[0046] Preferably, the alkyl glycol is selected from any one of 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, triethylene glycol or neopentyl glycol, or a combination of at least two thereof.

[0047] Preferably, the cycloalkyl diol is selected from 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,3-cyclopentanediol, 1,3-adamantanediol, 1,3-cyclohexanediol, piperanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, inositol, D-pinitol, D-chiral alcohol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, preferably 1,4-cyclohexanediol or 1,4-cyclohexanedimethanol.

[0048] Preferably, the aromatic diol is selected from bisphenol A, bisphenol S, bisphenol C, bisphenol Z, bisphenol AP, 4,4′-biphenol and terephthalic acid, preferably terephthalic acid and bisphenol Z.

[0049] Preferably, the polymerization reaction is carried out in the presence of a catalyst.

[0050] Preferably, the catalyst is selected from any one or a combination of at least two of tetrabutyl titanate, tetraisopropyl titanate, tetraisobutyl titanate, tetraisooctyl titanate, zinc lactate, zinc acetate, diethyl zinc, cobalt lactate or cobalt acetate, preferably zinc acetate.

[0051] Preferably, the polymerization reaction temperature is 120-270°C, for example, 120°C, 130°C, 140°C, 150°C, 160°C, 180°C, 200°C, 220°C, 240°C, 260°C, 270°C, etc., and the reaction time is 3-15h, for example, 3h, 5h, 8h, 10h, 12h, 14h, 15h, etc.

[0052] Preferably, the viscosity of the polyester polymer solution obtained by the polymerization reaction is lower than 30 mPa·s, for example, 29 mPa·s, 28 mPa·s, 25 mPa·s, 24 mPa·s, 22 mPa·s, 20 mPa·s, etc.

[0053] Preferably, the UV absorber containing a hydroxyl group is selected from methyl salicylate, octyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone, UV-326, UV-327, ethylhexyl triazone , UV-1577, UV-1164 or UV-400 or a combination of at least two thereof, preferably octyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, UV-327, UV-1577 or UV-400 or a combination of at least two thereof, further preferably 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

[0054] Preferably, the added amount of the hydroxyl-containing UV absorber is 1-2% by mass of the polyester polymer, for example, 1%, 1.1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, etc.

[0055] Preferably, the reaction temperature is 120-200°C, for example, 120°C, 130°C, 140°C, 150°C, 160°C, 180°C, 200°C, etc., and the reaction time is 5-8h, for example, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, etc.

[0056] Preferably, the preparation method comprises:

[0057] (1) Preparation of polyester resin solution

[0058] The dicarboxylic acid is dissolved in the corresponding diol compound under nitrogen protection, and then zinc acetate is added as a catalyst. The mixture is stirred at 200°C for 6-14 hours. When no more water flows out of the reaction system, 1-2% of the corresponding UV absorber is added and stirred for another 5-8 hours to obtain a polyester resin solution.

[0059] (2) Preparation of polyester resin precipitate

[0060] The polyester resin solution is diluted with deionized water, and the mixture is filtered to obtain a polyester resin precipitate;

[0061] (3) Preparation of polyester resin powder

[0062] The polyester resin is precipitated and dried in a vacuum drying oven to obtain polyester resin powder;

[0063] (4) Preparation of water-soluble polyester resin

[0064] The polyester resin powder is dissolved in deionized water, and a neutralizing agent (triethylamine) is added to adjust the pH of the solution to neutral to obtain a water-soluble polyester resin solution.

[0065] Preferably, the temperature of the vacuum drying oven is 50-70°C, for example, 50°C, 52°C, 55°C, 58°C, 60°C, 62°C, 65°C, 68°C, 70°C, etc., and the drying time is 20-30h, for example, 20h, 22h, 24h, 25h, 26h, 28h, 30h, etc.

[0066] Preferably, the neutralizing agent is selected from any one or a combination of at least two of ethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, aqueous ammonia, tributylamine, n-butylamine, sodium hydroxide or potassium hydroxide, preferably triethylamine.

[0067] The polyester resin provided by the present invention has excellent high temperature resistance, is easy to wash with water, and has good storage stability. Therefore, when it is applied to a plasma cutting protective liquid, it can make the plasma cutting protective liquid resistant to high temperatures and easy to wash with water, and has high selectivity and a high selective etching ratio.

[0068] In the present invention, the plasma cutting protection liquid containing the water-soluble polyester resin can be resistant to high temperatures, has high selectivity, has a high selective etching ratio, and is easy to wash with water.

[0069] In a third aspect, the present invention provides a plasma cutting protection liquid comprising the following components in parts by weight:

[0070] 20-40 parts of the polyester resin described in the first aspect;

[0071] 50-80 parts of solvent.

[0072] In the present invention, the content of the polyester resin can be 20 parts, 23 parts, 25 parts, 28 parts, 30 parts, 33 parts, 35 parts, 38 parts, 40 parts, etc. The content of the solvent can be 50 parts, 55 parts, 58 parts, 60 parts, 63 parts, 65 parts, 68 parts, 70 parts, 73 parts, 75 parts, 78 parts, 80 parts, etc.

[0073] Preferably, the solvent is a mixed solvent of an inorganic solvent and an organic solvent.

[0074] Preferably, the organic solvent is selected from one or more of propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, glycerol methyl ether, ethylene glycol ethyl ether, glycerol trimethyl ether, glycerol ethyl ether, and diethylene glycol butyl ether, preferably propylene glycol methyl ether.

[0075] Preferably, the inorganic solvent is water, preferably deionized water.

[0076] Preferably, the mass ratio of the organic solvent to the inorganic solvent is 1:4-6, for example, 1:4, 1:4.3, 1:4.5, 1:4.8, 1:5, 1:5.3, 1:5.5, 1:5.8, 1:6, etc., preferably 1:4.5.

[0077] In a fourth aspect, the present invention provides a method for preparing the plasma cutting protection liquid as described in the third aspect, the preparation method comprising: mixing a polyester resin and a solvent to obtain the plasma cutting protection liquid.

[0078] Preferably, the preparation method comprises: adding polyester resin into water, heating and stirring to dissolve, then cooling and adding organic solvent, stirring and mixing, and filtering to obtain the plasma cutting protection liquid.

[0079] Preferably, the temperature is raised to 50-80°C, such as 50°C, 55°C, 58°C, 60°C, 65°C, 68°C, 70°C, 75°C, 78°C, 80°C, etc.

[0080] Preferably, the heating and stirring time is 2-4 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, etc.

[0081] Preferably, the cooling is to below 30°C, such as 30°C, 28°C, 25°C, 20°C, 18°C, 15°C, etc.

[0082] Preferably, the stirring time after adding the organic solvent is 0.5-2 h, for example, 0.5 h, 0.8 h, 1 h, 1.5 h, 1.8 h, 2 h, etc.

[0083] Preferably, the filtration is performed using 1.0 μm, 0.5 μm, and 0.1 μm filter membranes in sequence.

[0084] In a fifth aspect, the present invention provides an application of the plasma cutting protection liquid as described in the third aspect in a chip etching process.

[0085] The polyester resin provided by the present invention is a water-soluble polyester resin, which has excellent high-temperature resistance. When interacting with laser, it can prevent the resin from undergoing a cross-linking reaction and losing its water-solubility. At the same time, during the plasma gas etching process, the heat resistance of the film can significantly reduce the plasma etching rate, protect the underlying chip from damage, improve the chip etching yield, and will not affect the cleanability of the protective film.

[0086] The polyester resin provided by the present invention can control the molecular weight of the obtained resin by controlling the condensation time. The low molecular weight resin can obtain a denser protective film after coating, resist the influence of physical etching and chemical etching, and can form a thinner film layer to protect the functional area.

[0087] In a sixth aspect, the present invention provides a method for using the plasma cutting protection liquid as described in the third aspect, the method comprising:

[0088] placing the plasma cutting protection liquid on the surface of the wafer to form a protective film;

[0089] When the size of the wafer is 4 inches, the dosage is 10-20mL, for example, 10mL, 12mL, 15mL, 18mL, 20mL, etc.; when the size of the wafer is 8 inches, the dosage is 20-40mL, for example, 20mL, 25mL, 30mL, 35mL, 40mL, etc., and so on. Preferably, the dosage of the plasma cutting protection liquid is 10-160mL.

[0090] Preferably, the thickness of the protective film is 2-10 μm, for example, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., preferably 4-6 μm.

[0091] Preferably, the method of use comprises:

[0092] Apply the plasma cutting protection liquid to the center of the wafer surface, spin-coat the protection liquid evenly on the wafer surface and spin dry.

[0093] Preferably, the spin coating speed is 600-1500 rpm, for example, 600 rpm, 800 rpm, 1000 rpm, 1200 rpm, 1500 rpm, etc., and the spin coating time is 150-250 s, for example, 150 s, 180 s, 200 s, 220 s, 240 s, 250 s, etc.

[0094] According to the usage method provided by the present invention, the plasma cutting protection liquid is spin-coated to form a protective film, and wafer grooving, plasma etching, etc. can be performed. After the wafer etching is completed, deionized water can be used to dissolve and clean the remaining residues, stains, and the protective film.

[0095] Compared with the prior art, the present invention has the following beneficial effects:

[0096] (1) The polyester resin provided by the present invention has UV absorbing groups, and no additional UV light absorber needs to be added, thereby avoiding the problem of unstable storage performance caused by the mutual repulsion between the polyester resin and the UV absorber;

[0097] (2) The polyester resin provided by the present invention is not only water-soluble and easy to wash, but also has excellent high-temperature resistance, which can prevent the polyester resin from losing its water-washability due to cross-linking at high temperatures;

[0098] (3) The plasma cutting protection liquid provided by the present invention is resistant to high temperatures, easy to wash with water, has good coating and film-forming effect, has a smaller heat-affected zone and a higher selective etching ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 This is the infrared spectrum of the polyester resin provided in Preparation Example 1.

[0100] Figure 2 This is a diagram showing the heat-affected zone results of a dry etching experiment using the plasma cutting protection fluid provided in Example 1.

[0101] Figure 3 This is a film thickness diagram before dry etching using the plasma cutting protection liquid prepared in Example 1.

[0102] Figure 4This is a film thickness diagram after dry etching using the plasma cutting protection liquid prepared in Example 1.

[0103] Figure 5 This is an etching depth map after dry etching using the plasma cutting protection liquid prepared in Example 1. DETAILED DESCRIPTION

[0104] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0105] Preparation Example 1

[0106] This preparation example provides a method for preparing a polyester resin, as follows:

[0107] (1) Preparation of polyester resin solution

[0108] Dimethyl isophthalate (1.05 mol), sodium isophthalate-5-sulfonate (1.0 mol), and ethylene glycol (2 mol) were heated to react under nitrogen protection, and then zinc acetate (0.01 mol) was added, and the mixture was stirred at 200° C. for 8 h. When no water flowed out of the reaction system, the corresponding UV-326 (0.004 mol) was added and stirred for another 30 min to obtain a polyester resin solution; after keeping the temperature at 220° C. for 2 hours, N2 was turned off, and the mixture was evacuated, a large amount of by-product ethylene glycol was distilled out, and the vacuum degree was slowly increased to 10 Pa. After evacuating the mixture for 5 h, the reaction was terminated, and the product was poured out to obtain the water-soluble polyester resin;

[0109] (2) Preparation of polyester resin precipitate

[0110] Dilute the polyester resin solution 2 times with deionized water, and filter the mixture to obtain polyester resin precipitate;

[0111] (3) Preparation of polyester resin powder

[0112] The polyester resin precipitate was dried in a vacuum drying oven at 60°C for 24 hours to obtain polyester resin powder;

[0113] (4) Preparation of water-soluble polyester resin

[0114] 100 g of polyester resin powder was dissolved in 250 g of deionized water, and triethylamine was added to adjust the pH of the solution to neutral to obtain a water-soluble polyester resin solution; the molecular weight was approximately 20,000 (weight-average molecular weight was measured using an ultra-high performance polymer chromatograph (ACQUITY APC) from Waters).

[0115] Performance Testing

[0116] The infrared performance analysis of the polyester resin obtained in Preparation Example 1 was performed, and the results were as follows:

[0117] Figure 1 The infrared spectrum of the polyester resin provided in Preparation Example 1 is Figure 1 It can be seen that at 1700cm -1 There are two new infrared absorption peaks near the wave number, indicating that a new ester bond is generated, proving that the esterification reaction can proceed smoothly

[0118] Preparation Example 2-4

[0119] This preparation example provides a method for preparing a polyester resin.

[0120] The difference from Preparation Example 1 is that in this Preparation Example, the added UV absorbers are 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (Preparation Example 2), 2,4-dihydroxybenzophenone (Preparation Example 3), and 2,2',4,4'-tetrahydroxybenzophenone (Preparation Example 4).

[0121] Preparation Example 5-10

[0122] This preparation example provides a method for preparing a polyester resin.

[0123] The preparation method refers to Preparation Example 1. The specific composition and addition amount of each component are shown in Table 1, unit mol:

[0124] Table 1

[0125]

[0126] Examples 1-10

[0127] This embodiment provides a plasma cutting protection liquid and a preparation method thereof, as follows:

[0128] (1) Weigh 22 g of the polyester resin solid provided in Preparation Example 1-10, 10 g of propylene glycol methyl ether, and 45 g of deionized water and mix them;

[0129] (2) Add 45 g of deionized water to a container, add the polyester resin solid to the deionized water in small amounts and in multiple batches, heat to 80°C, and stir for 2 h until uniform and transparent;

[0130] (3) Turn off the heating device, continue to stir the polyester resin aqueous solution until the temperature drops below 30°C, add propylene glycol methyl ether, and stir for 30 minutes;

[0131] (4) The solution in step 3 is filtered in sequence with a filtration accuracy of 1.0 μm, 0.5 μm, and 0.1 μm to obtain the plasma cutting protection liquid.

[0132] Example 11

[0133] This embodiment provides a plasma cutting protection liquid and a preparation method thereof, as follows:

[0134] (1) Weigh 40 g of the polyester resin solid provided in Preparation Example 1, 11 g of propylene glycol methyl ether, and 66 g of deionized water and mix them;

[0135] (2) Add 66 g of deionized water to a container, add the polyester resin solid to the deionized water in small amounts and in multiple batches, heat to 80°C, and stir for 2 h until uniform and transparent;

[0136] (3) Turn off the heating device, continue to stir the polyester resin aqueous solution until the temperature drops below 30°C, add propylene glycol methyl ether, and stir for 30 minutes;

[0137] (4) The solution in step 3 is filtered in sequence with a filtration accuracy of 1.0 μm, 0.5 μm, and 0.1 μm to obtain the plasma cutting protection liquid.

[0138] Comparative Example 1

[0139] This comparative example provides a plasma cutting protective liquid.

[0140] The difference from Example 1 is that in this example, the polyester resin solid provided in Preparation Example 1 is replaced by an equal weight portion of polyester resin without UV monomer but with consistent molecular chains and an equal weight portion of an added UV absorber (UV-326).

[0141] Comparative Examples 2-4

[0142] This comparative example provides a plasma cutting protective liquid.

[0143] The difference from Example 1 is that in this embodiment, the polyester resin solid provided in Preparation Example 1 is replaced by an equal weight part of a polyester resin having no UV monomer but a consistent molecular chain and an equal weight part of an added UV absorber (2-hydroxy-4-methoxybenzophenone, Comparative Example 2), (2,4-dihydroxybenzophenone, Comparative Example 3), and (2,2',4,4'-tetrahydroxybenzophenone, Comparative Example 4).

[0144] Performance Test 2

[0145] The performance test of the plasma cutting protection liquid provided in the examples and comparative examples was carried out as follows:

[0146] (1) Storage stability at room temperature: The samples were stored at room temperature and the storage conditions of the protective solution were observed for 10 days, 30 days, 60 days, 100 days, 150 days, 200 days, and 400 days to determine whether there was particle precipitation. The test results are shown in Table 2:

[0147] Table 2

[0148] Storage time 10d 30d 60d 100d 150d 200d 400d Example 1 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Example 2 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Example 3 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Example 4 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Example 5 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Example 6 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Example 7 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Example 8 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Example 9 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Example 10 No precipitation No precipitation No precipitation No precipitation No precipitation precipitation - Example 11 No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation No precipitation Comparative Example 1 No precipitation No precipitation precipitation Comparative Example 2 No precipitation No precipitation precipitation Comparative Example 3 No precipitation No precipitation precipitation Comparative Example 4 No precipitation No precipitation precipitation

[0149] From the examples and performance tests, the plasma cutting protection fluid provided by the present invention has better storage stability, which can exceed 150 days, and optimally exceed 400 days; while the storage stability time of the plasma cutting protection fluid provided by the comparative example fails to exceed 60 days.

[0150] (2) Heat resistance test: Using a TGA instrument (Netzsch: TG209F3, Germany), the 2% and 5% thermal weight loss temperatures of the plasma cutting protective liquid after film formation were tested. The test results are shown in Table 3 below:

[0151] Table 3

[0152]

[0153]

[0154] As can be seen from Table 4, the adhesive films prepared using the plasma cutting protective liquid provided by the embodiments of the present invention have a 2% thermal weight loss temperature exceeding 350°C and a 5% thermal weight loss temperature exceeding 355°C, showing excellent heat resistance.

[0155] From the comparison between Example 1 and Comparative Examples 1-4, it can be seen that replacing the polyester resin disclosed in the present invention with a polyester resin without a UV absorber and introducing an additional UV absorber will lead to a decrease in the thermal stability of the plasma cutting protection liquid. Among them, the 2% thermal weight loss temperature of the adhesive film prepared by the plasma cutting protection liquid provided by Comparative Examples 1 and 2 is lower than 300°C, and the thermal stability is poor due to high-temperature denaturation. The thermal stability of Comparative Examples 3-4 also decreases.

[0156] (3) Cleaning Ability: 20 mL of each of the plasma cutting protection solutions provided in the above examples and comparative examples were applied to a 12-inch wafer using spin coating parameters of 1000 rpm and 120 s, respectively, and then laser cutting was immediately performed. After chip cutting was completed, the remaining residue and stains were dissolved and cleaned along with the plasma cutting protection solution film using deionized water. The cleaning effect was observed, and the test results are shown in Table 4 below.

[0157] Table 4

[0158]

[0159]

[0160] It can be seen from Table 4 that the protective films made by the plasma cutting protective liquid provided by the embodiment of the present invention can be cleaned under water drop conditions and have excellent water solubility and cleaning ability, while the protective film made by the plasma cutting protective liquid provided by Comparative Example 4 cannot be cleaned by water flow.

[0161] (4) Vacuum film surface: Place the film-formed wafer in a vacuum environment and observe the film surface. The test results are shown in Table 5.

[0162] Table 5

[0163] Test subjects Vacuum membrane surface Example 1 intact Example 2 intact Example 3 intact Example 4 intact Example 5 intact Example 6 intact Example 7 intact Example 8 intact Example 9 intact Example 10 intact Example 11 intact Comparative Example 1 intact Comparative Example 2 intact Comparative Example 3 intact Comparative Example 4 intact

[0164] It can be seen from Table 5 that the membrane surfaces of the embodiment and the comparative example are intact under vacuum conditions.

[0165] (5) Absorption coefficient: Spin-coat the plasma cutting protection liquid on a 4-inch glass, use clean glass as the substrate, select a wavelength of 300-800nm ​​for testing, select the transmittance value at 355nm, and then use a step meter to measure the film thickness. Calculate the absorption coefficient according to the absorption coefficient formula.

[0166] Heat-affected zone: After the laser cutting process is completed, the wafer is placed under an optical microscope to observe the edge exposed by the laser cutting path and measure the size of the area with burrs on the edge. The test results are as follows:

[0167] Figure 2 This is a result diagram of the heat-affected zone of a dry etching experiment conducted with the plasma cutting protection liquid provided in Example 1. As can be seen from the figure, the heat-affected zone caused by the plasma cutting protection liquid provided in Example 1 is less than 0.9 μm.

[0168] The results of the remaining embodiments and comparative examples are shown in Table 6:

[0169] Table 6

[0170] Test subjects Absorption coefficient Heat affected zone size / μm Example 1 1.55 ＜1.9 Example 2 1.60 ＜0.9 Example 3 1.50 ＜1.6 Example 4 1.59 ＜1.9 Example 5 1.61 ＜0.8 Example 6 1.63 ＜0.9 Example 7 1.62 ＜1.0 Example 8 1.60 ＜0.9 Example 9 1.58 ＜0.8 Example 10 1.50 ＜1.6 Example 11 1.55 ＜1.9 Comparative Example 1 0.82 ＜4.6 Comparative Example 2 0.71 ＜4.5 Comparative Example 3 0.93 ＜5.0 Comparative Example 4 1.13 ＜4.0

[0171] As can be seen from Table 6, the absorption coefficients of the films made from the plasma cutting protection fluid provided by the embodiments of the present invention are all ≥1.5, and they have extremely strong absorption capacity for a light source with a wavelength of 355nm, while the absorption coefficients of the films made from the plasma cutting protection fluid provided by the comparative example are all lower than 1.2, and their absorption capacity for a light source with a wavelength of 355nm is relatively poor; for the heat-affected zone data analysis: the heat-affected zone caused by the plasma cutting protection fluid provided by the present invention is less than 2.0μm, while the heat-affected zone of the comparative example is greater than 4.0μm, indicating that the plasma cutting protection fluid provided by the present invention is more suitable for the plasma cutting process.

[0172] (6) Etching depth: Use an etcher to perform a plasma dry etching test and observe the cross section.

[0173] Selectivity: Use an etcher to conduct a plasma dry etching test, measure the film thickness based on a refractive index of 1.3, and calculate the selectivity. The test results are as follows:

[0174] Figure 3 This is the film thickness map before dry etching using the plasma cutting protection liquid prepared in Example 1. Figure 4 This is the film thickness diagram after dry etching using the plasma cutting protection liquid prepared in Example 1. Figure 5 The etching depth diagram after dry etching using the plasma cutting protection liquid prepared in Example 1 is shown. As can be seen from the figure, the etching depth of Example 1 of the present invention is 84 μm, which is relatively deep, and the etching consumption is below 0.25, and the etching selectivity is greater than 300.

[0175] The results of the remaining embodiments and comparative examples are shown in Table 7:

[0176] Table 7

[0177] Test subjects Cross-section depth / μm Etching consumption / μm Etching selectivity Example 1 83 0.276 301 Example 2 85 0.246 346 Example 3 82 0.258 318 Example 4 82 0.244 336 Example 5 85 0.237 359 Example 6 85 0.243 350 Example 7 84 0.250 336 Example 8 83 0.244 340 Example 9 80 0.258 310 Example 10 81 0.260 312 Example 11 83 0.276 301 Comparative Example 1 77.6 2.01 39 Comparative Example 2 78.1 2.60 30 Comparative Example 3 77.5 1.72 45 Comparative Example 4 80.1 0.598 134

[0178] It can be seen from Table 7 that the etching depths of the embodiments of the present invention are all greater than 80 μm, and the etching depths are relatively deep, while the etching depths of the comparative examples are relatively low, but the difference is not significant.

[0179] It can also be seen from Table 7 that the selectivity of the embodiments of the present invention can all exceed 300, indicating that the plasma cutting protection liquid provided by the invention has a higher unit etching ability, and with the same film thickness loss, the etching depth is higher.

[0180] The applicant states that while the above-described embodiments illustrate the process of the present invention, the present invention is not limited to the above-described process steps, nor does it imply that the present invention must rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A polyester resin, characterized in that The polyester resin has a structure shown in the following formula I: in, "UV—" indicates the residue of a UV absorber; R1 and R3 are each independently selected from the residue of a polycarboxylic acid, the residue of an acid anhydride or the residue of a polycarboxylic acid ester; R2 and R4 are each independently selected from the residue of an alkyl diol, the residue of an aromatic diol or the residue of a cycloalkyl diol; n is an integer from 20 to 300.

2. The polyester resin according to claim 1, wherein The UV absorber is selected from salicylate UV absorbers, benzophenone UV absorbers, benzotriazole UV absorbers or triazine UV absorbers, preferably benzophenone UV absorbers; Preferably, the structural formula of the salicylate UV absorber is Y is selected from methyl, ethyl, n-propyl or octyl, preferably octyl; Preferably, the benzophenone UV absorber is selected from 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone, preferably 2,2'-dihydroxy-4,4'-dimethoxybenzophenone; Preferably, the benzotriazole UV absorber is selected from UV-326 or UV-327, preferably UV-327; Preferably, the triazine UV absorber is selected from ethylhexyl triazone, UV-1577, UV-1164 or UV-400, preferably UV-1577 or UV-400.

3. The polyester resin according to claim 1 or 2, characterized in that R1 and R3 are each independently selected from in: X is O, N or S; Indicates the group attachment site.

4. The polyester resin according to any one of claims 1 to 3, characterized in that R2 and R4 are each independently selected from in: Indicates the group attachment site.

5. The polyester resin according to any one of claims 1 to 4, characterized in that The polyester resin is selected from any one of the following resins: wherein n is an integer of 20-300, preferably an integer of 20-50; Preferably, the weight average molecular weight of the polyester resin is 20,000-200,000, preferably 50,000-100,000.

6. A method for preparing a polyester resin according to any one of claims 1 to 5, characterized in that: The preparation method comprises: reacting a polyester polymer with a UV absorber containing a hydroxyl group to obtain the polyester resin; in: The structural formula of polyester polymer is R1 and R3 are each independently selected from the residue of a polycarboxylic acid, the residue of an acid anhydride or the residue of a polycarboxylic acid ester; R2 and R4 are each independently selected from the residue of an alkyl diol, the residue of an aromatic diol or the residue of a cycloalkyl diol; n is an integer from 20 to 300; Preferably, the added amount of the hydroxyl-containing UV absorber is 1-2% of the mass of the polyester polymer; Preferably, the reaction temperature is 120-200° C. and the reaction time is 5-8 h.

7. A plasma cutting protective liquid, characterized in that: Calculated by weight, it includes the following components: 20-40 parts of the polyester resin according to any one of claims 1-5; 50-80 parts of solvent; Preferably, the solvent is a mixed solvent of an inorganic solvent and an organic solvent; Preferably, the organic solvent is selected from one or more of propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol butyl ether, glycerol methyl ether, ethylene glycol ethyl ether, glycerol trimethyl ether, glycerol ethyl ether, and diethylene glycol butyl ether, preferably propylene glycol methyl ether; Preferably, the inorganic solvent is water, preferably deionized water; Preferably, the mass ratio of the organic solvent to the inorganic solvent is 1:4-6, preferably 1:4.

5.

8. A method for preparing a plasma cutting protection liquid according to claim 7, characterized in that: The preparation method comprises: mixing polyester resin and solvent to obtain the plasma cutting protection liquid.

9. Use of the plasma cutting protection liquid according to claim 7 in a chip etching process.

10. A method for using the plasma cutting protection liquid according to claim 7, characterized in that: The method of use includes: placing the plasma cutting protection liquid on the surface of the wafer to form a protective film; Preferably, the amount of the plasma cutting protection liquid is 10-160 mL; Preferably, the thickness of the protective film is 2-10 μm, preferably 4-6 μm.

Images