Temporary protection material and solution of temporary protection material

Abstract

The purpose of the present invention is to provide: a temporary protection material which can be easily removed with water having ordinary temperature or a low temperature; and a solution of the temporary protection material. A temporary protection material according to the present invention is for use as a protection material during semiconductor production, and includes a poly(vinyl alcohol)-based resin including a modified poly(vinyl alcohol)-based resin. When ultrasonic vibration is applied to the temporary protection material for three minutes in water having a temperature of 35±5°C at the time of initiation of the ultrasonic application, under the conditions of a frequency of 45±5 kHz and an ultrasonic output of 100±10 W / 2.5±0.5 L of water, then the temporary protection material has a gel content of 50 wt% or less.

Description

Temporary protective material and temporary protective material solution

[0001] The present invention relates to a temporary protective material and a temporary protective material solution.

[0002] During processing of electronic components such as semiconductors, in order to facilitate handling of the electronic components and prevent damage, the electronic components are protected by being fixed to a support plate via a pressure-sensitive adhesive composition or by being attached with a pressure-sensitive adhesive tape. For example, when a thick-film wafer cut from a high-purity silicon single crystal or the like is ground to a predetermined thickness to obtain a thin-film wafer, the thick-film wafer is adhered to a support plate via a pressure-sensitive adhesive composition.

[0003] Thus, adhesive compositions and adhesive tapes used for electronic components are required to have high adhesiveness sufficient to firmly secure electronic components during processing, as well as the ability to peel the electronic components without damaging them after the processing is completed (hereinafter also referred to as "high adhesive and easy peeling"). As a means of achieving high adhesive and easy peeling, for example, Patent Document 1 discloses a method in which an adhesive is applied to the surface of a temporary holding substrate to form a temporary adhesive layer, a semiconductor wafer is adhered and fixed so that the tip ends of the bumps are embedded in this temporary adhesive layer, and then the temporary adhesive layer is dissolved with a solvent to remove the chip-type electronic components from the temporary holding substrate. Patent Document 2 also discloses a configuration in which a protective layer is formed by covering the surface of a wafer with a liquid mixture of polyvinyl alcohol, sodium lauryl ether sulfate, and sodium α-olefin sulfonate. Furthermore, Patent Document 3 discloses a wafer dividing method in which a film containing a polyvinyl alcohol-based polymer having a degree of polymerization of 100 to 3000 and a saponification degree of 70 to 99 mol% is bonded to the semiconductor wafer.

[0004] Patent No. 4078760 Utility Model Registration No. 3221770 Patent No. 5563341

[0005] In recent years, 3D packaging has been adopted for mounting electronic components with the aim of increasing the density and yield of integrated circuits. In 3D packaging, peripheral elements such as capacitors and solder balls are mounted on various surfaces, including the top and back surfaces of chip-type electronic components, in addition to integrated circuits. In 3D packaging, due to process constraints, peripheral elements may be placed on the back surface before the integrated circuit is mounted on the top surface. In such cases, there is a risk of scratches or damage to the chip-type electronic component due to the back surface elements coming into contact with the stage when the integrated circuit is mounted on the top surface. For this reason, protective sheets are used to protect the elements that are mounted on the back surface first, but these protective sheets must be removed after multiple integrated circuits are placed on the front surface. Removal using organic solvents or other chemicals poses problems such as increased environmental impact and the generation of protective sheet residue. Therefore, a temporary protective material that can be removed in a short time using room-temperature or low-temperature water is needed.

[0006] An object of the present invention is to provide a temporary protective material and a temporary protective material solution that can be easily removed with water at room temperature or low temperature.

[0007] The present disclosure (1) is a temporary protective material used as a protective material during semiconductor manufacturing, the temporary protective material containing a polyvinyl alcohol-based resin including a modified polyvinyl alcohol-based resin, wherein the gel fraction is 50% by weight or less when ultrasonic vibrations are applied for 3 minutes in water having a water temperature of 35±5°C at the start of ultrasonic application under conditions of a frequency of 45±5 kHz, an ultrasonic output of 100±10 W / 2.5±0.5 L of water. The present disclosure (2) is the temporary protective material of the present disclosure (1), in which the modified polyvinyl alcohol-based resin has a structural unit having a polar group. The present disclosure (3) is the temporary protective material of the present disclosure (2), in which the polar group is a sulfonic acid group. The present disclosure (4) is the temporary protective material of any one of the present disclosures (1) to (3), in which the modified polyvinyl alcohol-based resin has a degree of saponification of 70 mol% or more and 100 mol% or less and an average degree of polymerization of 300 or more and 4500 or less. The present disclosure (5) is the temporary protective material of any one of the present disclosures (1) to (4), in which the polyvinyl alcohol-based resin contains 50% by weight or more and 100% by weight or less of a modified polyvinyl alcohol-based resin. The present disclosure (6) is the temporary protective material of any one of the present disclosures (1) to (5), in which the crosslinking agent is not contained or the content of the crosslinking agent is 0.1% by weight or less. The present disclosure (7) is the temporary protective material of any one of the present disclosures (1) to (6), further containing an alcohol compound, the alcohol compound having two or more hydroxyl groups and a hydroxyl value of 40 or less. The present disclosure (8) is the temporary protective material of the present disclosure (7), in which the content of the alcohol compound is 5% by weight or more and 50% by weight or less. The present disclosure (9) is a temporary protective material solution containing the temporary protective material of any one of the present disclosures (1) to (8) and a solvent containing water. The present disclosure (10) is a temporary protective material solution containing the temporary protective material of the present disclosure (6) and a solvent containing water. The present invention will be described in detail below.

[0008] The present inventors discovered that by making a temporary protective material containing a modified polyvinyl alcohol resin and having a gel fraction of 50% by weight or less as measured by a specified method, it is possible to make a temporary protective material that can protect the component mounting surface during the mounting process of a semiconductor substrate and can be easily removed with low-temperature water, and thus completed the present invention.

[0009] <Polyvinyl alcohol-based resin> The temporary protective material of the present invention contains a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin includes a modified polyvinyl alcohol-based resin. By containing the modified polyvinyl alcohol-based resin, it is possible to provide a temporary protective material that can sufficiently protect the component mounting surface in the mounting process of a semiconductor substrate and can be easily removed with water.

[0010] The saponification degree of the polyvinyl alcohol resin is preferably 70 mol% or more and preferably 100 mol% or less. By adjusting the degree within this range, a temporary protective material exhibiting water solubility suitable for cleaning can be obtained. The saponification degree is more preferably 80 mol% or more, even more preferably 85 mol% or more, particularly preferably 91 mol% or more, more preferably 99.9 mol% or less, even more preferably 99 mol% or less, and particularly preferably 97 mol% or less. The saponification degree can be measured, for example, by a method conforming to JIS K6726. The saponification degree indicates the proportion of vinyl ester units that can be converted to vinyl alcohol units by saponification that are actually converted to vinyl alcohol units. The saponification degree can be controlled, for example, by adjusting the saponification conditions, i.e., the hydrolysis conditions.

[0011] The average degree of polymerization of the polyvinyl alcohol resin is preferably 300 or more, more preferably 450 or more, even more preferably 600 or more, particularly preferably 800 or more, and is preferably 4500 or less, more preferably 3000 or less, even more preferably 2000 or less, particularly preferably 1500 or less. The average degree of polymerization can be determined, for example, by measuring the viscosity of polyvinyl acetate before saponification by gel permeation chromatography (GPC) or by measuring the viscosity of an aqueous solution in accordance with JIS K6726.

[0012] The polyvinyl alcohol resin may contain the modified polyvinyl alcohol resin, and may be a mixed resin of multiple modified polyvinyl alcohol resins with different compositions, or a mixed resin of a modified polyvinyl alcohol resin and an unmodified polyvinyl alcohol resin. When the polyvinyl alcohol resin is a mixed resin of multiple polyvinyl alcohol resins with different compositions, the saponification degree can be determined by multiplying the content (wt%) of each polyvinyl alcohol resin in the polyvinyl alcohol resin by the saponification degree (mol%), dividing the result by 100, and then adding up the results. Similarly, the weight average molecular weight, number average molecular weight, and average degree of polymerization of the mixed resin can be determined by multiplying the content (wt%) of each polyvinyl alcohol resin in the polyvinyl alcohol resin by the respective values, dividing the result by 100, and then adding up the results.

[0013] The polyvinyl alcohol resin includes a modified polyvinyl alcohol resin. The modified polyvinyl alcohol resin preferably has a structural unit having a polar group. By adopting the above-mentioned configuration, a temporary protective material can be obtained that can sufficiently protect a component mounting surface during a mounting process of a semiconductor substrate and can be more easily removed with water.

[0014] Examples of the polar group include a sulfonic acid group, a pyrrolidone ring group, an amino group, an amide group, a carboxyl group, etc. Among these, a sulfonic acid group is preferred because it is more easily removed with water.

[0015] When the polar group has a sulfonic acid group, examples of the structural unit having a sulfonic acid group include a structural unit represented by the following formula (1).

[0016]

[0017] In the above formula (1), R １ and R ２ each independently represents an alkylene group having 0 to 4 carbon atoms, an amide group (—CONH—), an ester group (—COO—), or an ether group (—O—); X １ represents a hydrogen atom, a metal atom, or an alkyl group having 1 to 3 carbon atoms.

[0018] Examples of the alkylene group having 0 to 4 carbon atoms include a single bond, a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, or a tetramethylene group, and a branched alkylene group such as a propylene group (1-methylethylene group, 2-methylethylene group), a butylene group (1-ethylethylene group, 2-ethylethylene group), a 1,2-dimethylethylene group, a 2,2-dimethylethylene group, a 1-methyltrimethylene group, a 2-methyltrimethylene group, or a 3-methyltrimethylene group. Of these, a 2,2-dimethylethylene group is preferred.

[0019] In the above formula (1), X １ represents a hydrogen atom, a metal atom, or an alkyl group having 1 to 3 carbon atoms. Examples of the metal atom include a sodium atom, a lithium atom, and a potassium atom, and among these, a sodium atom is preferred. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, and a propyl group. １ As the atom, a metal atom is preferred, and a sodium atom is more preferred.

[0020] The structural unit having a sulfonic acid group is preferably a structural unit having a salt of a sulfonic acid group represented by the following formula (1-1).

[0021]

[0022] In the above formula (1), R ３ represents an alkylene group having 0 to 4 carbon atoms, and among these, a 2,2-dimethylethylene group is preferred.

[0023] When the polar group has a pyrrolidone ring group, examples of the structural unit having a pyrrolidone ring group include structural units represented by the following formula (2).

[0024]

[0025] When the polar group has an amino group, examples of the structural unit having the amino group include a structural unit represented by the following formula (3).

[0026]

[0027] In the above formula (3), R ４is a single bond or an alkylene group having 1 to 10 carbon atoms, R ５ and R ６ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

[0028] Examples of the alkylene group having 1 to 10 carbon atoms include linear alkylene groups, branched alkylene groups, and cyclic alkylene groups. Examples of the linear alkylene group include a methylene group, a vinylene group, an n-propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, and a decamethylene group. Examples of the branched alkylene group include a methylmethylene group, a methylethylene group, a 1-methylpentylene group, and a 1,4-dimethylbutylene group. Examples of the cyclic alkylene group include a cyclopropylene group, a cyclobutylene group, and a cyclohexylene group. Of these, linear alkylene groups are preferred, with a methylene group, a vinylene group, and an n-propylene group being more preferred, and a methylene group and a vinylene group being even more preferred.

[0029] Examples of the alkyl group having 1 to 10 carbon atoms include linear alkyl groups such as methyl, ethyl, propyl, n-butyl, n-pentyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups; branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2,2-dimethylpropyl, 1,1,3,3-tetramethylbutyl, and 2-ethylhexyl groups; and cycloalkyl groups such as cyclopropyl, cyclopropylmethyl, cyclobutyl, cyclopentyl, and cyclohexyl groups.

[0030] When the polar group has an amide group, examples of the structural unit having the amide group include a structural unit represented by the following formula (4).

[0031]

[0032] In the above formula (4), R ７ is an alkylene group having 1 to 10 carbon atoms, R ８ represents an alkyl group having 1 to 10 carbon atoms. The alkylene group having 1 to 10 carbon atoms includes R ４Examples of the alkyl group having 1 to 10 carbon atoms include the alkyl group R ５ , R ６ The same can be mentioned.

[0033] The content of the structural unit having a polar group in the modified polyvinyl alcohol resin is preferably 1 mol% or more, more preferably 3 mol% or more, and particularly preferably 5 mol% or more, and is preferably 20 mol% or less, more preferably 15 mol% or less, and particularly preferably 12 mol% or less. The content of the structural unit having a polar group can be measured, for example, by NMR.

[0034] The saponification degree of the modified polyvinyl alcohol resin is preferably 70 mol% or more and preferably 100 mol% or less. By setting it within this range, sufficient strength and hardness as a temporary protective material can be imparted, and water resistance and cleanability can be highly compatible. The saponification degree is more preferably 80 mol% or more, even more preferably 85 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, more preferably 99.9 mol% or less, even more preferably 99 mol% or less, and particularly preferably 98 mol% or less.

[0035] The average degree of polymerization of the modified polyvinyl alcohol resin is preferably 300 or more, more preferably 500 or more, even more preferably 700 or more, particularly preferably 900 or more, and is preferably 4500 or less, more preferably 3000 or less, even more preferably 2000 or less, particularly preferably 1500 or less. By setting it within the above range, removability with water can be further improved.

[0036] The content of the structural unit having a polar group in the polyvinyl alcohol-based resin is preferably 1 mol% or more, more preferably 2 mol% or more, even more preferably 3.5 mol% or more, and preferably 20 mol% or less, more preferably 15 mol% or less, and even more preferably 10 mol% or less. When the polyvinyl alcohol-based resin is a mixed resin of multiple polyvinyl alcohol-based resins with different compositions, the content of the structural unit having a polar group can be determined by multiplying the content (% by weight) of each polyvinyl alcohol-based resin in the polyvinyl alcohol-based resin by the content (mol%) of the structural unit having a polar group, and dividing the result by 100, and then adding up the results.

[0037] From the viewpoint of removability with water, the content of the modified polyvinyl alcohol resin in the polyvinyl alcohol resin is preferably 5% by weight or more, more preferably 25% by weight or more, even more preferably 50% by weight or more, and particularly preferably 85% by weight or more, with the upper limit being 100% by weight.

[0038] The content of the modified polyvinyl alcohol resin in the temporary protective material of the present invention is preferably 50% by weight or more, more preferably 70% by weight or more, even more preferably 85% by weight or more, and is preferably 100% by weight or less, more preferably 95% by weight or less, even more preferably 90% by weight or less.

[0039] In the temporary protective material of the present invention, the content of the polyvinyl alcohol-based resin is preferably 50% by weight or more, more preferably 75% by weight or more, and even more preferably 85% by weight or more, and is preferably 100% by weight or less, more preferably 95% by weight or less, and even more preferably 90% by weight or less.

[0040] The polyvinyl alcohol resin can be obtained by polymerizing a vinyl ester to obtain a polymer, and then saponifying the polymer, i.e., by hydrolysis, in accordance with a conventionally known method. An alkali or an acid is generally used as a saponification catalyst.

[0041] Examples of the vinyl ester include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl laurate, vinyl stearate, and vinyl benzoate.

[0042] The method for polymerizing the vinyl ester is not particularly limited, but examples thereof include solution polymerization, bulk polymerization, and suspension polymerization.

[0043] Examples of polymerization catalysts used in polymerizing the vinyl ester include 2-ethylhexyl peroxydicarbonate ("Trigonox EHP" manufactured by Tianjin McEIT Co., Ltd.), 2,2'-azobisisobutyronitrile (AIBN), t-butyl peroxyneodecanoate, bis(4-t-butylcyclohexyl)peroxydicarbonate, di-n-propyl peroxydicarbonate, di-n-butyl peroxydicarbonate, di-cetyl peroxydicarbonate, and di-s-butyl peroxydicarbonate. One type of the polymerization catalyst may be used alone, or two or more types may be used in combination.

[0044] The polyvinyl alcohol resin may be a saponified polymer of a vinyl ester and another unsaturated monomer. Examples of the other unsaturated monomer include monomers other than the vinyl esters, which have an unsaturated double bond, such as a vinyl group. Specific examples include olefins, (meth)acrylic acid and salts thereof, (meth)acrylic acid esters, unsaturated acids other than (meth)acrylic acid, salts and esters thereof, (meth)acrylamides, N-vinylamides, vinyl ethers, nitriles, vinyl halides, allyl compounds, vinylsilyl compounds, isopropenyl acetate, sulfonic acid group-containing compounds, and amino group-containing compounds.

[0045] Examples of olefins include ethylene, propylene, 1-butene, and isobutene. Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Examples of unsaturated acids other than (meth)acrylic acid, and their salts and esters include maleic acid and its salts, maleic acid esters, itaconic acid and its salts, itaconic acid esters, methylenemalonic acid and its salts, and methylenemalonic acid esters. Examples of (meth)acrylamides include acrylamide, n-methylacrylamide, N-ethylacrylamide, and N,N-dimethylacrylamide. Examples of N-vinylamides include N-vinylpyrrolidone. Examples of vinyl ethers include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, and n-butyl vinyl ether. Examples of nitriles include (meth)acrylonitrile. Examples of vinyl halides include vinyl chloride and vinylidene chloride. Examples of allyl compounds include allyl acetate and allyl chloride. Examples of vinyl silyl compounds include vinyltrimethoxysilane. Examples of sulfonic acid group-containing compounds include (meth)acrylamidoalkanesulfonic acids such as (meth)acrylamidopropanesulfonic acids, such as 2-acrylamido-2-methylpropanesulfonic acid, and salts thereof; and olefinsulfonic acids such as ethylenesulfonic acid, allylsulfonic acid, and methallylsulfonic acid, and salts thereof. Examples of amino group-containing compounds include allylamine, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, and polyoxypropylene vinylamine.

[0046] <Alcohol Compound> The temporary protective material of the present invention may further contain an alcohol compound. The alcohol compound has two or more hydroxyl groups. By including the alcohol compound, removability with water can be further improved. Note that the alcohol compound is different from the organic solvent.

[0047] From the viewpoint of removability with water, the hydroxyl value of the alcohol compound is preferably 40 or less, more preferably 36 or less, and particularly preferably 33 or less. There is no particular limitation on the lower limit, but it is preferably 18 or more, more preferably 25 or more. The hydroxyl value is a value obtained by dividing the molecular weight of the alcohol compound by the number of hydroxyl groups in one molecule. When the alcohol compound contains a plurality of alcohol compounds with different hydroxyl values, the hydroxyl value can be determined by summing the product of the content (wt%) of each alcohol compound in the entire alcohol compound and the hydroxyl value, divided by 100.

[0048] Examples of the alcohol compounds include glycols, glycerins, and sugar alcohols. Examples of the glycols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, isoprene glycol, 1,3-butylene glycol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, and 1,2-decanediol. Examples of the glycerins include glycerin, diglycerin, and polyglycerin. Examples of the sugar alcohols include xylitol, trehalose, maltitol, mannitol, sorbitol, erythritol, arabitol, ribitol, galactitol, glucitol, and raffinose. Among these, glycerins and sugar alcohols are preferred, and glycerin, erythritol, and xylitol are more preferred.

[0049] In the temporary protective material of the present invention, the content of the above alcohol compound is preferably 1% by weight or more, more preferably 3% by weight or more, even more preferably 5% by weight or more, particularly preferably 10% by weight or more, from the viewpoint of removability with water, and is preferably 50% by weight or less, more preferably 30% by weight or less, and even more preferably 15% by weight or less.

[0050] <Crosslinking Agent> The temporary protective material of the present invention may contain a crosslinking agent, but preferably does not contain a crosslinking agent.

[0051] Examples of the crosslinking agent include oxoacids, boron compounds, diamines, polyamines, etc. Metal salts of the above acids may also be used.

[0052] Examples of the oxoacid include boric acid, polycarboxylic acid, and hydroxycarboxylic acid. The polycarboxylic acid is an acid having two or more carboxyl groups, and the hydroxycarboxylic acid is preferably an acid having two or more carboxyl groups. Metal salts of the above acids may also be used. Examples of boric acid include orthoboric acid, metaboric acid, and tetraboric acid. Examples of the boron compound include, in addition to the boric acids listed as the oxoacids, salts of boric acid. The boron compound may also be a hydrate. Examples of the salts of boric acid include alkali metal salts such as borax, alkaline earth metal salts such as calcium salts, and organic amine salts such as triethylamine. Examples of the polycarboxylic acid include oxalic acid, malonic acid, succinic acid, and phthalic acid. Examples of the hydroxycarboxylic acid include tartronic acid, malic acid, tartaric acid, citramalic acid, citric acid, and isocitric acid.

[0053] The content of the crosslinking agent in the temporary protective material of the present invention is preferably 0.1% by weight or less, and more preferably 0% by weight, from the viewpoint of removability with water.

[0054] The temporary protective material of the present invention may contain other components such as a storage stabilizer, a mechanical property improver, a thickener, a preservative, an antifungal agent, a dispersion stabilizer, a surfactant, and a spacer (gap adjusting material) as necessary, but it is preferable that the main components consist of a polyvinyl alcohol resin and a crosslinking agent.

[0055] The temporary protective material of the present invention has a gel fraction of 50% by weight or less when subjected to ultrasonic vibrations for 3 minutes in water with a water temperature of 35±5°C at the start of ultrasonic application under conditions of a frequency of 45±5 kHz, an ultrasonic output of 100±10 W / 2.5±0.5 L of water. A gel fraction of 50% by weight or less can ensure excellent removability with water. The gel fraction is preferably 30% by weight or less, more preferably 10% by weight or less, even more preferably 5% by weight or less, and particularly preferably 3% by weight or less. The lower the gel fraction, the better from the viewpoint of improved cleanability. Therefore, the preferred lower limit is not particularly limited, but is essentially 0% by weight or more. The temporary protective material of the present invention preferably has a low gel fraction; however, the gel fraction may increase due to additives added for purposes such as improving the moisture resistance of the protective film or for various other purposes. For example, the gel fraction may increase due to the addition of polycarboxylic acids or polyvalent metal ions as preservatives to the temporary protective material solution, or the addition of surfactants to improve cleanability. Even in this case, it is important to keep the content within the above range, but it is generally possible to control the gel fraction by controlling the amount added. For example, boric acid is a typical crosslinking agent for polyvinyl alcohol resins. By setting the molar ratio of boric acid to polyvinyl alcohol resin to less than 1, the crosslinking coefficient can be made less than 1, thereby preventing gelation. The crosslinking coefficient that can achieve a gel fraction of 50% by weight or less varies depending on the system and cannot be generally stated. However, since the gel fraction rapidly decreases as the crosslinking coefficient decreases, in most cases, if the content of the crosslinking agent is 0.1% by weight or less, the crosslinking coefficient is significantly below 1, and the gel fraction can be controlled to 50% by weight or less. The gel fraction can be determined by applying the temporary protective material of the present invention, drying it, and molding it to obtain a molded body, immersing it in water with a water temperature of 35±5°C at the start of ultrasonic application, stirring it using an ultrasonic cleaner to dissolve it, and then measuring the weight of the undissolved components and calculating the ratio of the weight of the undissolved components to the weight of the molded body before immersion. Depending on the formulation and supply form of the temporary protective material, it may be difficult to obtain a molded body by drying after coating as described above. In such cases, a predetermined, measurable weight of the temporary protective material may be collected as the dry weight, and ultrasonic waves may be applied as described above to determine the gel fraction.Such cases may include, for example, when the composition is fragile and unable to maintain its shape by itself. In such cases, it is possible to collect the composition in the form of scales, powder, or the like and store it in a stainless steel mesh basket before use. The frequency of the applied ultrasonic waves is appropriately selected within the range of 45±5 kHz, taking into consideration factors such as cleaning performance and damage to the object being cleaned. An example is 45 kHz. At lower frequencies, the cleaning power is improved but the load on the object being cleaned increases. Conversely, at higher frequencies, the cleaning power is slightly reduced but the load on the object being cleaned decreases. Furthermore, the ultrasonic output is appropriately selected within the range of 100±10 W / 2.5±0.5 L of water, an example being 100 W / 2.5 L of water.

[0056] The temporary protective material of the present invention is preferably removable within one minute when a protective film is formed by applying a 1 μm thick coating to a passivated silicon wafer and then performing shower cleaning by spraying pure water at 20°C. Examples of the application method include casting, roll coating, lip coating, spin coating, screen coating, fountain coating, dipping, and spraying. Examples of drying methods include natural drying and heat drying at a temperature below the glass transition temperature of the polyvinyl alcohol resin. Examples of methods for spraying pure water include, for example, a general manual or electric sprayer, as well as a simple device combining a water pump and a spray nozzle. Passivation refers to the oxidization and passivation of the surface of a metal or the like. In particular, in semiconductors, passivation refers to coating the surface of an element with a passive film to prevent the influence of external air and the adhesion of dust. For example, in silicon elements, a quartz film (SiO ) is formed during the manufacturing process. ２ The surface is protected by a layer of silicon nitride (SiN) or glass that is automatically formed on the surface, but it is common to further coat it with silicon nitride (SiN) by CVD (chemical vapor deposition) before dicing.

[0057] The method for producing the temporary protective material of the present invention is not particularly limited, and examples include a method in which a polyvinyl alcohol-based resin including a modified polyvinyl alcohol-based resin having a polar group, a solvent including water, and additives such as an alcohol compound are mixed to prepare a temporary protective material solution, which is then coated and dried. The temporary protective material solution further contains a solvent in addition to the components of the temporary protective material of the present invention. The temporary protective material of the present invention and a temporary protective material solution containing a solvent including water also constitute one aspect of the present invention.

[0058] <Solvent> The temporary protective material solution of the present invention contains a solvent. The solvent includes water. By using the above-mentioned configuration, it is possible to improve the coatability.

[0059] The solvent content in the temporary protective material solution of the present invention is preferably 75% by weight or more, more preferably 85% by weight or more, particularly preferably 88% by weight or more, and is preferably 98% by weight or less, more preferably 96% by weight or less, particularly preferably 94% by weight or less.

[0060] From the viewpoint of coatability, the water content in the solvent is preferably 50% by weight or more, more preferably 60% by weight or more, and even more preferably 80% by weight or more, and is preferably 100% by weight or less, more preferably 95% by weight or less, and even more preferably 90% by weight or less.

[0061] The solvent may contain an organic solvent. To minimize environmental impact, it is preferable to not contain an organic solvent. However, a certain amount of organic solvent may be contained for the purposes of improving fluidity during application, wettability to the substrate to be protected, and drying speed. Examples of the organic solvent include alcohols such as methanol, ethanol, and isopropanol, and ketones such as acetone and methyl ethyl ketone.

[0062] The content of the organic solvent in the solvent is preferably 0% by weight or more, more preferably 5% by weight or more, and even more preferably 10% by weight or more, and is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 20% by weight or less.

[0063] The use of the temporary protective material of the present invention is not particularly limited, but it is preferably used in the manufacturing process of electronic components such as semiconductor devices, display devices, etc. For example, in the mounting process of a semiconductor substrate, the temporary protective material of the present invention can protect the component mounting surface by applying the temporary protective material solution of the present invention to the component mounting surface and drying it to form a protective film, which can be easily removed with water.

[0064] Examples of methods for applying the temporary protective material solution of the present invention include casting, roll coating, lip coating, spin coating, screen coating, fountain coating, dipping, spraying, etc. Examples of drying methods include natural drying and heat drying at a temperature equal to or lower than the glass transition temperature of the polyvinyl alcohol-based resin.

[0065] According to the present invention, it is possible to provide a temporary protective material and a temporary protective material solution that can be easily removed with water at room temperature or low temperature.

[0066] 1 is a photograph showing the cleaning properties of the temporary protective material obtained in Example 1. FIG. 2 is a photograph showing the cleaning properties of the temporary protective material obtained in Comparative Example 1.

[0067] The following examples will explain the present invention in more detail, but the present invention is not limited to these examples.

[0068] (Example 1) A temporary protective material solution was prepared by dissolving 100 parts by weight of a polyvinyl alcohol-based resin in 900 parts by weight of water. As the polyvinyl alcohol-based resin, a modified polyvinyl alcohol-based resin PVA-A (saponification degree 95.4 mol%, average polymerization degree 1200, content of structural units having sulfonic acid groups 4 mol%) having a structural unit having a sulfonic acid group represented by the following formula (1-1-1) was used. The saponification degree of the polyvinyl alcohol-based resin was measured by a method in accordance with JIS K6726. The average polymerization degree of the polyvinyl alcohol-based resin was determined by measuring the viscosity of an aqueous solution in accordance with JIS K6726. Furthermore, the content of structural units having sulfonic acid groups was １３ Measurement was performed using C-NMR.

[0069]

[0070] (Examples 2 to 10, Comparative Example 1) Temporary protective material solutions were prepared in the same manner as in Example 1, except that the polyvinyl alcohol-based resin, alcohol compound, and type and content of solvent were as shown in Table 1. As the polyvinyl alcohol-based resin, PVA-A and unmodified polyvinyl alcohol-based resin PVA-B (saponification degree 88 mol%, average polymerization degree 600) were used.

[0071] (Evaluation) The temporary protective materials and temporary protective material solutions obtained in the Examples and Comparative Examples were evaluated as follows. The results are shown in Table 1.

[0072] <Measurement of gel fraction (45 kHz ultrasonic dissolution test)> The obtained temporary protective material solution was applied to a release-treated polyethylene terephthalate (PET) film using a Baker applicator so that the thickness after drying was 20 μm, and the solution was dried in a hot air circulating oven at 80 ° C. to remove the solvent, and a molded body (temporary protective material) was produced on the PET film. The molded body was peeled from the PET film and cut to 5 cm x 5 cm to prepare a test piece, and the initial weight was measured. 200 ml of pure water was placed in a 500 ml beaker, and the test piece was immersed. The beaker was then placed in an ultrasonic cleaner. The water temperature in the beaker was set to 35 ° C., and the ultrasonic cleaner was placed under conditions of a frequency of 45 kHz, an ultrasonic output of 100 W / 2.5 L of water, and then filtered through a 200 mesh stainless steel wire mesh, and the wire mesh was dried in an oven at 80 ° C. The weight of the undissolved component was calculated from the difference between the weight of the wire mesh before filtration and the weight of the wire mesh after filtration and drying. The gel fraction (wt %) was determined by calculating the ratio of the weight of the undissolved components to the initial weight of the test piece.

[0073] <Cleanability> The obtained temporary protective material solution was applied to a substrate (a test silicon wafer passivated with silicon nitride) using a spin coater so that the thickness after drying was 1 μm, and then dried by leaving it to stand in an oven at 80 ° C. for 30 minutes to form a protective film (temporary protective material). 10 ° C. pure water was sprayed onto the obtained protective film at a rate of 280 g / min using a sprayer (Koshin battery-powered sprayer 3LGT-3S) from a distance of 10 cm from the protective film, and after 10 seconds, water droplets on the surface were immediately removed with an air duster to check for any remaining protective film. If any remaining protective film was remaining, a test piece prepared separately in the same manner was sprayed for 20 seconds, and then water droplets on the surface were immediately removed with an air duster to check for any remaining protective film. In this way, the spray time was extended by 10 seconds until all the protective film was removed, and the time until the protective film was removed from the area sprayed with pure water was confirmed. The same operation was performed using pure water at 20 ° C., and the time until the protective film was removed was confirmed. Photographs of the temporary protective materials obtained in Example 1 and Comparative Example 1 when their cleanability was confirmed are shown in Figures 1 and 2. As can be seen from Figure 1, the temporary protective material obtained in Example 1 was sufficiently removed from the substrate after spraying at 10°C for 20 seconds. On the other hand, as can be seen from Figure 2, the temporary protective material obtained in Comparative Example 1 was not sufficiently removed from the substrate after spraying at 10°C for 20 seconds, with some of the temporary protective material remaining.

[0074]

[0075] According to the present invention, it is possible to provide a temporary protective material and a temporary protective material solution that can be easily removed with water at room temperature or low temperature.

Claims

1. A temporary protective material used as a protective material during semiconductor manufacturing, which contains a polyvinyl alcohol-based resin including a modified polyvinyl alcohol-based resin, and has a gel fraction of 50% by weight or less when ultrasonic vibrations are applied for 3 minutes in water with a water temperature of 35±5°C at the start of ultrasonic application under conditions of a frequency of 45±5 kHz and an ultrasonic output of 100±10 W / 2.5±0.5 L of water.

2. The temporary protective material according to claim 1, wherein the modified polyvinyl alcohol resin has a structural unit having a polar group.

3. The temporary protective material according to claim 2, wherein the polar group is a sulfonic acid group.

4. A temporary protective material described in any one of claims 1 to 3, wherein the modified polyvinyl alcohol resin has a degree of saponification of 70 mol% or more and 100 mol% or less and an average degree of polymerization of 300 or more and 4,500 or less.

5. A temporary protective material according to any one of claims 1 to 4, wherein the polyvinyl alcohol resin contains 50% by weight or more and 100% by weight or less of a modified polyvinyl alcohol resin.

6. The temporary protective material according to any one of claims 1 to 5, which does not contain a crosslinking agent or contains 0.1% by weight or less of a crosslinking agent.

7. The temporary protective material according to any one of claims 1 to 6, further comprising an alcohol compound, the alcohol compound having two or more hydroxyl groups and a hydroxyl value of 40 or less.

8. The temporary protective material according to claim 7, wherein the content of the alcohol compound is 5% by weight or more and 50% by weight or less.

9. A temporary protective material solution comprising the temporary protective material according to any one of claims 1 to 8 and a solvent containing water.

10. A temporary protective material solution comprising the temporary protective material according to claim 6 and a solvent containing water.

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