A water-soluble polyester resin, a plasma etching protection solution containing the same, and a preparation method and application thereof

Abstract

The present invention provides a water-soluble polyester resin, a plasma etching protection liquid containing the same, and a preparation method and application thereof. The water-soluble polyester resin has a structure shown in Formula I. The plasma etching protection liquid of the present invention can solve the problems in the prior art that the resin has poor water solubility and uncontrollable molecular weight; the plasma etching protection liquid has poor high temperature resistance, poor coating effect, is not easy to wash with water, and generates a large heat-affected zone and a low selective etching ratio during etching.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor manufacturing technology, and relates to a water-soluble polyester resin, a plasma etching protection liquid containing the same, and a preparation method and application thereof, and in particular to a plasma etching protection liquid with a high selectivity, and a preparation method and application thereof. Background Art

[0002] With the development of highly integrated and sophisticated semiconductors, the grain density on the wafer has gradually increased and the etch path width has gradually decreased, which has brought greater challenges to the wafer etching process.

[0003] Plasma etching of materials is divided into physical etching and chemical etching. In the past, the more common plasma deep silicon etching was used to create more space in the vertical direction of the silicon wafer and prepare more sophisticated micro-nano structures. Therefore, before etching, a nano-level mask needs to be realized through a photolithography process, which is difficult to implement and has high process costs. Plasma etching is to separate the manufactured grains from the wafer, and the width of the etching path is usually in the micron level, so the etching process window is much larger. However, for plasma etching technology, it is only necessary to coat a layer of protective film on the surface of the wafer, and then use the wafer to cut the protective film and other film layers applied by the previous process on the surface of the silicon substrate at the location where etching is required, to form a micron-level mask for plasma etching. Compared with photolithography, this process of making masks greatly saves process costs and reduces implementation difficulties, but it also puts forward new requirements for the function of the protective film.

[0004] The plasma etching protective liquid needs to have a certain light absorption ability and heat resistance to ensure that a mask with good morphology is formed during the etching process, so that the protective film at the etching position will not cause the surrounding film layer to be lifted up and affect the protectiveness of the film while the wafer is etched and vaporized. In addition, during the etching process, the protective film needs to be able to resist the physical and chemical etching of the plasma, that is, the protective film needs to have chemical stability to the etchant and needs to have a certain thickness to withstand the anisotropic ion bombardment of the plasma. Finally, the protective film needs to be washed after the plasma etching is completed, so the resin used for the protective film needs to ensure that it will not be excessively cross-linked during the high temperature process of plasma etching, thereby affecting the water washability of the protective film.

[0005] It is precisely because of the existence of the above problems that researchers have studied how to protect the wafer during cutting and have achieved certain results. For example, CN 118772722 A discloses a plasma etching protection material and a preparation method, a cleaning material and an application. The plasma etching protection material includes a water-soluble polyethylene amine resin or a polyacrylamide resin, an ultraviolet light absorber, a moisturizer and a first solvent, and the cleaning material includes a cleaning medium and a second solvent. Among them, the cleaning medium can adsorb the positively charged cationic polymer formed after the water-soluble resin is ionized by ionizing the negatively charged acid ions. The etching protection material and the cleaning material are used in combination with each other, so that the formed protective film can be easily cleaned and removed, reducing the particle residue on the chip surface.

[0006] CN 117777802 A discloses a plasma etching protective material, the components of which include: acrylic resin, toughening agent, hydrolysis aid and solvent. In the plasma etching protective material, the resin is partially hydrolyzed by the hydrolysis aid so that the hydrophilicity of the resin is enhanced, the miscibility with the solvent is improved, and a complete protective film can be formed on the surface of the wafer to resist plasma etching. The protective film formed after the cutting process is completed has extremely strong water solubility and can be easily removed, making the cleaning process simple.

[0007] CN118271608 A discloses a plasma etching protection solution composed of a water-soluble polyamide resin, the solution comprising a water-soluble polyamide resin, a cosolvent, an ultraviolet absorber and a solvent. The plasma etching protection solution of the invention has the advantages of good protection performance, easy water washing, no residue, etc., and can form a uniform and dense protection film through simple coating, providing good high temperature resistance and protection performance during the etching process, no cracking and slag after etching, and forming a good etching morphology.

[0008] Based on the above analysis of the prior art, it is found that the plasma etching protection liquid currently available on the market generally adds polyethylene amine resin, acrylic resin or polyamide resin. Although these resins have certain water solubility, when using high-energy plasma, these polymer coatings will be cross-linked after thermal activation and lose water solubility or the resin structure will be destroyed, resulting in a larger heat-affected zone and a lower etching selectivity, which brings great challenges to the subsequent etching of chips or particle cleaning. Therefore, it is urgent to develop a plasma etching protection liquid with high temperature resistance, high selectivity, smooth and dense film surface after film formation, and easy water washing. Summary of the invention

[0009] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a water-soluble polyester resin, a plasma etching protection liquid containing the same, and a preparation method and application thereof. The plasma etching protection liquid of the present invention can solve the problems of the prior art such as poor water solubility of the resin and uncontrollable molecular weight; poor high temperature resistance of the plasma etching protection liquid, poor coating effect, difficulty in water washing, large heat-affected zone during etching, and low selective etching ratio.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] In one aspect, the present invention provides a water-soluble polyester resin having a structure as shown in the following formula I:

[0012]

[0013] Wherein R1 and R3 are independently selected from the residues of polycarboxylic acids, acid anhydrides or polycarboxylic acid esters, and at least one of R1 and R3 contains a sodium sulfonate group, R2 and R4 are independently selected from the residues of alkyl diols, the residues of aromatic diols or the residues of cycloalkyl diols, and n is selected from an integer of 20-300 (for example, 20, 30, 40, 50, 80, 100, 120, 150, 180, 200, 230, 250, 280 or 300, etc.).

[0014] Preferably, R1 and R3 are independently selected from Where X is O, N or S, and the wavy line represents the attachment site of the group.

[0015] Preferably, R2 and R4 are independently selected from

[0016] The wavy lines represent the attachment sites of the groups.

[0017] Preferably, the water-soluble polyester resin is selected from any one of the following resins:

[0018]

[0019]

[0020]

[0021] Preferably, the water-soluble polyester resin has a weight average molecular weight of 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 or 200,000.

[0022] In another aspect, the present invention provides a method for preparing the water-soluble polyester resin as described above, the preparation method comprising the following steps:

[0023] A carboxylic acid, anhydride or carboxylate compound with an R1 group, a diol compound with an R2 group, a carboxylic acid, anhydride or carboxylate compound with an R3 group and a diol compound with an R4 group are polymerized to obtain the water-soluble polyester resin;

[0024] Preferably, the carboxylic acid, anhydride or carboxylate compound with an R1 group or the carboxylic acid, anhydride or carboxylate compound with an R3 group is selected from any one or a combination of at least two of the following compounds:

[0025] 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 acid anhydrides; phthalic acid / phthalic anhydride, isophthalic acid / dimethyl isophthalate, isophthalic acid-5-sulfonic sodium, isophthalic acid-5-sulfonic sodium dimethyl ester, terephthalic acid, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, phthalic acid Aromatic carboxylic acids or anhydrides or esters such as dioctyl ester, 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; heteroaryl carboxylic acids or esters such as furandicarboxylic acid / furandicarboxylic acid dimethyl ester, pyrrole dicarboxylic acid, and thiophene dicarboxylic acid, and one or more combinations of the above compounds are preferably D-camphoric acid, 1,1-cyclopropanedicarboxylic acid, dimethyl phthalate, sodium 5-sulfonate of isophthalic acid, isophthalic acid, trimellitic anhydride, and furandicarboxylic acid dimethyl ester.

[0026] In the present invention, since at least one of R1 and R3 contains a sodium sulfonate group, at least one of the carboxylic acid, anhydride or carboxylate compound with an R1 group or the carboxylic acid, anhydride or carboxylate compound with an R3 group is selected from compounds with a sodium sulfonate group, preferably sodium 5-sulfoisophthalic acid.

[0027] Preferably, the diol compound with an R2 group or the diol compound with an R4 group is selected from an alkyl diol, a cycloalkyl diol or an aromatic diol.

[0028] Preferably, the alkyl diol 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.

[0029] 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-pinetol, D-chiral alcohol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, preferably 1,4-cyclohexanediol or 1,4-cyclohexanedimethanol.

[0030] 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.

[0031] Preferably, the polymerization reaction is carried out in the presence of a catalyst.

[0032] 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.

[0033] 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 or 270°C, and the reaction time is 3-15h, for example 3h, 5h, 8h, 10h, 12h, 14h or 15h.

[0034] In the present invention, the viscosity of the water-soluble polyester resin solution obtained by the polymerization reaction is lower than 30 mPa·s.

[0035] In the present invention, the preparation method of the water-soluble polyester resin comprises the following steps:

[0036] Step 1: Preparation of polyester resin solution;

[0037] Dissolve the dicarboxylic acid in the corresponding diol compound under nitrogen protection, then add zinc acetate as a catalyst; stir at 200°C for 6 to 14 hours to obtain a polyester resin solution;

[0038] Step 2: Preparation of polyester resin precipitate;

[0039] The polyester resin solution is diluted with ultrapure water, and the mixture is filtered to obtain a polyester resin precipitate;

[0040] Step 3: Preparation of polyester resin powder;

[0041] The polyester resin is precipitated and dried in a vacuum drying oven to obtain polyester resin powder;

[0042] Step 4: synthesizing water-soluble polyester resin;

[0043] The polyester resin powder is dissolved in ultrapure water, and triethylamine is added to adjust the pH of the solution to neutral to obtain a water-soluble polyester resin solution;

[0044] The temperature of the vacuum drying oven in step 3 is 50-70° C., and the drying time is 20-30 hours.

[0045] The neutralizing agent in step 4 can also be any one or more combinations of ethylamine, diethylamine, monoethanolamine, diethanolamine, triethanolamine, ammonia water, tributylamine, n-butylamine, sodium hydroxide, and potassium hydroxide, preferably triethylamine.

[0046] On the other hand, the present invention provides a plasma etching protection solution, wherein the plasma etching protection solution comprises the following components in parts by weight:

[0047]

[0048]

[0049] In the present invention, the plasma etching protection solution 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.

[0050] In the plasma etching protection solution of the present invention, the content of the water-soluble polyester resin can be 20 parts, 23 parts, 25 parts, 28 parts, 30 parts, 33 parts, 35 parts, 38 parts or 40 parts.

[0051] In the plasma etching protection solution of the present invention, the content of the ultraviolet absorber can be 0.1 parts, 0.5 parts, 0.8 parts, 1 parts, 1.5 parts, 1.8 parts, 2 parts, 2.3 parts, 2.5 parts, 2.8 parts or 3 parts.

[0052] In the plasma etching protection solution of the present invention, 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 or 80 parts.

[0053] In the plasma etching protection solution of the present invention, the content of the co-solvent can be 1 part, 3 parts, 5 parts, 8 parts, 10 parts, 12 parts or 15 parts.

[0054] Preferably, the ultraviolet absorber may be one or a combination of at least two of 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-acrylate benzophenone dimethylaminopropyl acrylate copolymer, 2,2'-dihydroxy 4,4'-dimethoxybenzophenone-5,5'-disulfonate sodium, 4-diethylaminoketo acid, coumarin 3-carboxylic acid, 4,4'-bis(2-sulfonic styrene)1,1'-biphenyl, and diethylhexyl butyl triazone, preferably 4,4'-bis(2-sulfonic styrene)1,1'-biphenyl.

[0055] Preferably, the solvent is a mixed solvent of an inorganic solvent and an organic solvent.

[0056] 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.

[0057] Preferably, the inorganic solvent is water, preferably ultrapure water.

[0058] 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 or 1:6, preferably 1:4.5.

[0059] Preferably, the co-solvent is one or a combination of at least two of isopropanol, isobutanol, 1,3-propylene glycol, 1,3-butylene glycol, diethylene glycol or glycerol, preferably glycerol.

[0060] On the other hand, the present invention also provides a method for preparing the plasma etching protection solution as described above, the preparation method comprising the following steps:

[0061] The water-soluble polyester resin is dissolved in water, the temperature is increased, stirred, and then the temperature is decreased, an organic solvent and an ultraviolet absorber are added, stirred, and then filtered to obtain the plasma etching protection solution.

[0062] Preferably, the heating is to 50-80°C, for example, 50°C, 55°C, 58°C, 60°C, 65°C, 68°C, 70°C, 75°C, 78°C or 80°C.

[0063] Preferably, the stirring time after heating is 2 to 4 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours.

[0064] Preferably, the cooling is to below 30°C, such as 30°C, 28°C, 25°C, 20°C, 18°C ​​or 15°C.

[0065] Preferably, the stirring time after adding the organic solvent and the ultraviolet absorber is 0.5 to 2 h, for example, 0.5 h, 0.8 h, 1 h, 1.5 h, 1.8 h or 2 h.

[0066] Preferably, the filtration is performed using filter membranes of 1.0 μm, 0.5 μm, and 0.1 μm in sequence.

[0067] On the other hand, the present invention provides a method for using the plasma etching protection solution as described above, the method comprising the following steps:

[0068] Apply the plasma etching protection liquid to the center of the wafer surface, spin-coat the protection liquid evenly on the wafer surface and spin dry.

[0069] Preferably, when the plasma etching protection liquid is coated on the center of the wafer surface, the amount of the protection liquid is 10-30 mL, for example, 10 mL, 13 mL, 15 mL, 18 mL, 20 mL, 23 mL, 25 mL, 28 mL or 30 mL.

[0070] Preferably, when the protective liquid is evenly spin-coated on the wafer surface, the spin-coating speed is 600-1500rpm, for example, 600rpm, 800rpm, 1000rpm, 1200rpm or 1500rpm, and the spin-coating time is 150-250s, for example, 150s, 180s, 200s, 220s, 240s or 250s.

[0071] On the other hand, the present invention provides use of the plasma etching protection solution as described above in a chip etching process.

[0072] In the present invention, the water-soluble polyester resin has excellent high temperature resistance, which can prevent the resin from undergoing a cross-linking reaction and losing its water-soluble properties when interacting with the laser; at the same time, during the plasma gas etching process, the heat resistance of the film can significantly reduce the plasma etching rate, protecting the underlying chip from damage, thereby not affecting the cleanability of the protective film and improving the chip etching yield.

[0073] In addition, a low molecular weight resin can be obtained by shortening the polymerization time, so that a denser protective film can be obtained after coating, which can resist the influence of physical etching and chemical etching and protect the functional area with a thinner film layer.

[0074] In the present invention, the main function of the co-solvent is to help the formed protective film to be easily and thoroughly peeled off from the wafer surface with deionized water during the cleaning stage after etching, so that no particles remain on the wafer surface.

[0075] The inventors have found that the water-soluble polyester resin synthesized by the present invention can have high temperature resistance while ensuring water solubility, and the thermal decomposition temperature exceeds 350° C. In addition, polymers with different molecular weight ranges (20,000 to 200,000) can be obtained by controlling the polymerization reaction time to meet different viscosity requirements.

[0076] In the present invention, after the plasma etching protection liquid is spin-coated to form a protection film according to the steps in the method of use, wafer grooving and plasma etching can be performed. After the chip etching is completed, the remaining residues and stains can be dissolved and cleaned together with the protection liquid film using deionized water.

[0077] Compared with the prior art, the present invention has the following beneficial effects:

[0078] (1) The present invention synthesizes a water-soluble resin with an ester structure. The unique structure of the resin ensures the etching resistance and high temperature resistance of the film layer while taking into account the cleanability of the film layer. The molecular weight of the resin can be controlled, thereby adjusting the film thickness of the protective liquid film layer according to different chip surface structures.

[0079] (2) The present invention provides a plasma etching protection liquid that is easy to form a film, has good protection performance, is easy to wash with water, and has no residue. The plasma etching protection liquid can form a uniform and dense protection film by simple coating, provides good protection performance in the etching process, has no cracking or slag after etching, forms a good etching morphology, and improves the chip etching yield. After use, the protective film can be peeled off by simply washing with deionized water to avoid residual protection liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 This is the infrared spectrum of the water-based polyester resin prepared in Example 1.

[0081] Figure 2 This is a result diagram of the heat affected zone of a dry etching experiment using the plasma etching protection solution prepared in Example 1.

[0082] Figure 3A This is a film thickness diagram before dry etching using the plasma etching protection solution prepared in Example 1;

[0083] Figure 3B This is a film thickness diagram after dry etching using the plasma etching protection solution prepared in Example 1;

[0084] Figure 3CThis is an etching depth map after dry etching using the plasma etching protection solution prepared in Example 1. DETAILED DESCRIPTION

[0085] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0086] Preparation method of polyester resin

[0087] Example 1

[0088] Step 1: Preparation of polyester resin solution;

[0089] Trimellitic anhydride (1.0 mol), sodium dimethyl isophthalate-5-sulfonate (1.0 mol), and ethylene glycol (3.05 mol) were heated to react under nitrogen protection, and then zinc acetate (0.01 mol) was added and stirred at 200° C. for 8 hours to obtain a polyester resin solution.

[0090] Step 2: Preparation of polyester resin precipitate;

[0091] The polyester resin solution is diluted to 2 times with ultrapure water, and the polyester resin precipitate is obtained after filtering.

[0092] Step 3: Preparation of polyester resin powder;

[0093] The mixture was filtered and the precipitate was dried in a vacuum drying oven at 60° C. for 24 h to obtain polyester resin powder.

[0094] Step 4: Synthesize water-soluble polyester resin

[0095] 100 g of polyester resin powder was dissolved in 250 g of ultrapure water, and triethylamine was added to adjust the pH of the solution to neutral to obtain a water-soluble polyester resin solution, and a polymer with a molecular weight of about 20,000 (the weight average molecular weight was tested using an ultra-high performance polymer chromatograph, whose manufacturer is: Waters, model: ACQUITY APC) was obtained.

[0096] The infrared spectrum of the prepared water-soluble polyester resin is as follows: Figure 1 As shown by Figure 1 It can be seen that at 1700cm -1 There are two new infrared absorption peaks near the wave number, indicating that new ester bonds are generated, proving that the esterification reaction can proceed smoothly.

[0097] Example 2

[0098] Step 1: Preparation of polyester resin solution;

[0099] Isophthalic acid (1.0 mol), sodium dimethyl isophthalate-5-sulfonate (1.0 mol), diethylene glycol (1.05 mol), and 1,3-propylene glycol (2.0 mol) were heated to react under nitrogen protection, and then zinc acetate (0.01 mol) was added and stirred at 200° C. for 8 hours to obtain a polyester resin solution.

[0100] Step 2: Preparation of polyester resin precipitate;

[0101] The polyester resin solution is diluted to 2 times with ultrapure water, and the polyester resin precipitate is obtained after filtering.

[0102] Step 3: Preparation of polyester resin powder;

[0103] The mixture was filtered and the precipitate was dried in a vacuum drying oven at 60° C. for 24 h to obtain polyester resin powder.

[0104] Step 4: Synthesize water-soluble polyester resin

[0105] 100 g of polyester resin powder was dissolved in 250 g of ultrapure water, and triethylamine was added to adjust the pH of the solution to neutral to obtain a water-soluble polyester resin solution, and a polymer with a molecular weight of about 50,000 (weight average molecular weight was tested using an ultra-high performance polymer chromatograph, whose manufacturer is: Waters, model: ACQUITY APC) was obtained.

[0106] Example 3

[0107] Step 1: Preparation of polyester resin solution;

[0108] Dimethyl terephthalate (1.0 mol), sodium dimethyl isophthalate-5-sulfonate (1.0 mol), tetraethylene triol (2.05 mol), and adamantane diol (1.0 mol) were heated to react under nitrogen protection, and then zinc acetate (0.01 mol) was added and stirred at 200° C. for 8 h to obtain a polyester resin solution.

[0109] Step 2: Preparation of polyester resin precipitate;

[0110] The polyester resin solution is diluted to 2 times with ultrapure water, and the polyester resin precipitate is obtained after filtering.

[0111] Step 3: Preparation of polyester resin powder;

[0112] The mixture was filtered and the precipitate was dried in a vacuum drying oven at 60° C. for 24 h to obtain polyester resin powder.

[0113] Step 4: Synthesize water-soluble polyester resin

[0114] 100 g of polyester resin powder was dissolved in 250 g of ultrapure water, and triethylamine was added to adjust the pH of the solution to neutral to obtain a water-soluble polyester resin solution, and a polymer with a molecular weight of about 40,000 (weight average molecular weight was tested using an ultra-high performance polymer chromatograph, whose manufacturer is: Waters, model: ACQUITY APC) was obtained.

[0115] Preparation method of plasma etching protection solution:

[0116] Step 1: Weigh the respective components in their respective amounts: 40 g of water-based polyester resin solid, 10 g of propylene glycol methyl ether, 0.5 g of 4,4'-bis(2-sulfonatophenylvinyl)-1,1'-biphenyl, and 100 g of ultrapure water.

[0117] Step 2: Add 45 g of ultrapure water into a container, add the water-soluble polyester resin into the ultrapure water in small amounts and multiple times, heat to 80°C, and stir for 2 hours until it becomes uniform and transparent;

[0118] Step 3: Turn off the heating device, continue to stir the polyester resin aqueous solution until the temperature drops below 30°C, add the organic solvent propylene glycol methyl ether and the ultraviolet absorber 4,4'-bis(2-sulfonylphenyl)-1,1'-biphenyl, and stir for 30 minutes;

[0119] Step 4: Filter the solution in step 3 in sequence with a filtration accuracy of 1.0 μm-0.5 μm-0.1 μm to obtain a high temperature resistant plasma etching protection solution.

[0120] Performance Test Results

[0121] The plasma etching protection solution prepared as above was used to perform a picosecond laser grooving experiment to observe the heat affected zone of 1.8 μm (such as Figure 2 As shown in the figure, the heat affected zone generated by the plasma etching protection liquid currently sold on the market during the etching process is all above 2.5μm.

[0122] As can be seen from Figure 3, the film thickness before etching is 5.98μm, the film thickness after etching is 5.61μm, the etching consumption is 0.37μm, the etching depth is 88.6μm, and the obtained selectivity is 239. The plasma etching protection solution currently sold on the market produces a selectivity of less than 130 during the etching process, which has met the needs of industrial production.

[0123] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A water-soluble polyester resin, characterized in that The water-soluble polyester resin has a structure as shown in the following formula I: Wherein R1 and R3 are independently selected from the residues of polycarboxylic acids, anhydrides or polycarboxylic acid esters, and at least one of R1 and R3 contains a sodium sulfonate group, R2 and R4 are independently selected from the residues of alkyl diols, aromatic diols or cycloalkyl diols; and n is selected from an integer of 20-300.

2. The water-soluble polyester resin according to claim 1, characterized in that R1 and R3 are independently selected from Where X is O, N or S, and the wavy line represents the attachment site of the group; Preferably, R2 and R4 are independently selected from The wavy lines represent the attachment sites of the groups.

3. The water-soluble polyester resin according to claim 1 or 2, characterized in that The water-soluble polyester resin is selected from any one of the following resins:

4. The water-soluble polyester resin according to any one of claims 1 to 3, characterized in that The weight average molecular weight of the water-soluble polyester resin is 20,000-200,000.

5. A method for preparing a water-soluble polyester resin as claimed in any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: The water-soluble polyester resin is obtained by polymerizing a carboxylic acid, anhydride or carboxylate compound with an R1 group, a diol compound with an R2 group, a carboxylic acid, anhydride or carboxylate compound with an R3 group and a diol compound with an R4 group.

6. The preparation method according to claim 5, characterized in that: The carboxylic acid, anhydride or carboxylate compound with an R1 group or the carboxylic acid, anhydride or carboxylate compound with an R3 group is selected from any one or a combination of at least two of the following compounds: 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 acid anhydrides; phthalic acid / phthalic anhydride, isophthalic acid / dimethyl isophthalate, isophthalic acid-5-sulfonic sodium, isophthalic acid-5-sulfonic sodium dimethyl ester, terephthalic acid, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, phthalic acid Aromatic carboxylic acids or anhydrides or esters such as dioctyl ester, 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; heteroaryl carboxylic acids or esters such as furandicarboxylic acid / furandicarboxylic acid dimethyl ester, pyrrole dicarboxylic acid, and thiophene dicarboxylic acid, one or more combinations of the above compounds, preferably D-camphoric acid, 1,1-cyclopropanedicarboxylic acid, dimethyl phthalate, sodium 5-sulfonate of isophthalic acid, isophthalic acid, trimellitic anhydride, and furandicarboxylic acid dimethyl ester; Preferably, at least one of the carboxylic acid, anhydride or carboxylate compound with an R1 group or the carboxylic acid, anhydride or carboxylate compound with an R3 group is selected from compounds with a sodium sulfonate group, preferably sodium 5-sulfoisophthalate; Preferably, the diol compound with an R2 group or the diol compound with an R4 group is selected from an alkyl diol, a cycloalkyl diol or an aromatic diol; Preferably, the alkyl diol is selected from any one or a combination of at least two of 1,2-propylene glycol, 1,3-propylene glycol, diethylene glycol, triethylene glycol or neopentyl glycol; 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; 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; Preferably, the polymerization reaction is carried out in the presence of a catalyst; 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; Preferably, the polymerization reaction temperature is 120-270°C, and the reaction time is 3-15h; Preferably, the viscosity of the water-soluble polyester resin solution obtained by the polymerization reaction is lower than 30 mPa·s.

7. A plasma etching protection solution, characterized in that: The plasma etching protection solution comprises the following components in parts by weight: Preferably, the ultraviolet absorber can be one or a combination of at least two of 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-acrylate benzophenone dimethylaminopropyl acrylate copolymer, 2,2'-dihydroxy 4,4'-dimethoxybenzophenone-5,5'-disulfonate sodium, 4-diethylamino keto acid, coumarin 3-carboxylic acid, 4,4'-bis(2-sulfonic acid styrene) 1,1'-biphenyl, and diethylhexyl butyl ester triazone, preferably 4,4'-bis(2-sulfonic acid styrene) 1,1'-biphenyl; 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 ultrapure water; Preferably, the mass ratio of the organic solvent to the inorganic solvent is 1:4-6; Preferably, the co-solvent is one or a combination of at least two of isopropanol, isobutanol, 1,3-propylene glycol, 1,3-butylene glycol, diethylene glycol or glycerol, preferably glycerol.

8. The method for preparing a plasma etching protection solution according to claim 7, characterized in that: The preparation method comprises the following steps: Dissolving a water-soluble polyester resin in water, heating, stirring, and then cooling, adding an organic solvent and an ultraviolet absorber, stirring, and then filtering to obtain the plasma etching protection solution; Preferably, the temperature is increased to 50-80°C; Preferably, the stirring time after heating is 2 to 4 hours; Preferably, the cooling is to below 30°C; Preferably, the stirring time after adding the organic solvent and the ultraviolet absorber is 0.5 to 2 hours; Preferably, the filtration is performed using filter membranes of 1.0 μm, 0.5 μm, and 0.1 μm in sequence.

9. The method for using the plasma etching protection solution according to claim 7, characterized in that: The method of use comprises the following steps: Applying plasma etching protection liquid to the center of the wafer surface, evenly spin-coating the protection liquid on the wafer surface and spin-drying it; Preferably, when the plasma etching protection liquid is coated on the center of the wafer surface, the amount of the protection liquid is 10-30 mL; Preferably, when the protection liquid is evenly spin-coated on the wafer surface, the spin-coating speed is 600-1500 rpm and the spin-coating time is 150-250 s.

10. Use of the plasma etching protection solution according to claim 7 in a chip etching process.

Images