PROCESS SOLUTION FOR POLYMER PROCESSING

The present disclosure relates to a process solution for polymer processing, containing a polar aprotic solvent, a fluorine-based compound, and a sulfur-containing compound. The process solution for polymer processing may have excellent storage stability and minimize damage to the metal layer while improving an ability to remove the adhesive polymer remaining on a circuit surface of a semiconductor wafer.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to Korean Patent Application No. 10-2020-0173172, filed on Dec. 11, 2020, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

Technical Field

The present disclosure relates to a process solution for polymer processing capable of minimizing damage to a metal layer while improving an ability to remove an adhesive polymer.

Description of the Related Art

In the manufacturing process of a semiconductor element, after an electronic circuit, etc. is formed on a surface of a semiconductor wafer (hereinafter also referred to as a ‘wafer’), back grinding of the wafer is sometimes performed in order to reduce a thickness of the wafer. In this case, in order to protect a circuit surface of the wafer and to fix the wafer, a support is usually attached to the circuit surface of the wafer with an adhesive polymer such as a silicon polymer interposed therebetween. When the support is attached to the circuit surface of the wafer, it is possible to reinforce the wafer whose thickness has been reduced after back grinding of the wafer, and a back electrode, etc., may be formed on the ground surface of the wafer.

When a process such as the back grinding of the wafer and the formation of the back electrode is completed, the support is removed from the circuit surface of the wafer, the adhesive polymer is peeled off and removed, and the wafer is cut to manufacture a chip.

Meanwhile, recently, a chip stacking technique using a through electrode (e.g., a silicon through electrode) installed through a wafer has been developed. According to this chip stacking technique, since the electronic circuits of a plurality of chips are electrically connected by using through electrodes instead of conventional wires, it is possible to achieve high integration of the chips and speed up the operation. When this chip stacking technique is used, in many cases, the back grinding of the wafer is performed in order to reduce the thickness of an aggregate on which a plurality of chips are stacked, and thus, an opportunity to use a support or an adhesive polymer increases.

However, because the support is generally attached to the circuit surface of the wafer with the adhesive polymer interposed therebetween and thermal curing is then performed for firm attachment of the wafer and the support, when the adhesive polymer is peeled off, the cured adhesive polymer may remain on the support and the circuit surface of the wafer. Therefore, there is a need for a means capable of efficiently removing the cured adhesive polymer remaining on the circuit surface of the wafer while preventing damage to the wafer or a metal film.

Meanwhile, Korean Patent Laid-Open Publication No. 10-2014-0060389 discloses a composition for removing an adhesive polymer, but has problems in that the removal rate for a network polymer is slow or removability of a linear polymer is reduced, and damage to the metal layer occurs.

RELATED ART DOCUMENT

SUMMARY

The present disclosure is to improve the problems of the prior art described above, and an object of the present disclosure is to provide a process solution for polymer processing capable of minimizing damage to a metal layer while improving an ability to remove an adhesive polymer remaining on a circuit surface of wafer in a semiconductor manufacturing process.

However, the problem to be solved by the present disclosure is not limited to those mentioned above, and the other unmentioned problems will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the present disclosure provides a process solution for polymer processing, containing a polar aprotic solvent, a fluorine-based compound, and a sulfur-containing compound.

Advantageous Effects

The present disclosure provides a process solution for polymer processing capable of preventing damage to a metal layer while improving an ability to remove an adhesive polymer remaining on a circuit surface of a wafer in a semiconductor manufacturing process by containing a polar aprotic solvent, a fluorine-based compound, and a sulfur-containing compound.

DETAILED DESCRIPTION

The present disclosure relates to a process solution for polymer processing, containing a polar aprotic solvent, a fluorine-based compound, and a sulfur-containing compound, and the process solution for polymer processing may prevent damage to a metal layer while improving an ability to remove an adhesive polymer remaining on the circuit surface of a semiconductor wafer or the metal layer.

The adhesive polymer includes a silicone-based resin, and may contain not only a linear non-reactive polydimethylsiloxane-based polymer, but also a polyorganosiloxane resin that forms a network polymer through curing.

In the present disclosure, a process solution for polymer processing contains a polymer cleaning solution, a polymer stripping solution, and a polymer etching solution, and the polymer cleaning solution is most preferable.

Throughout the present specification, the term “alkyl group” refers to a hydrocarbon group linked by a single bond.

<Process Solution for Polymer Processing>

The process solution for polymer processing according to the present disclosure may contain a polar aprotic solvent, a fluorine-based compound, and a sulfur-containing compound, and may further contain other additives.

In addition, the process solution for polymer processing according to the present disclosure does not contain water that is artificially injected, and does not preferably contain substantially water. However, a hydrate of the fluorine-based compound may be used if necessary, and as a result, a small amount of water may be contained. In this case, the small amount of water may be contained in an amount of less than 4% by weight based on the total weight of the composition. When water is optionally contained, the removability to a polymer such as a silicone resin may be lowered, and damage to a metal film may be increased.

In addition, it is preferable that the process solution for polymer processing according to the present disclosure does not contain a compound including a hydroxide (—OH) group in a molecular structure, such as an alcohol-based compound. When a hydroxide group is included in the molecular structure, there may be a problem in that the activity of the fluorine-based compound is inhibited, such that the removability of the silicone resin is reduced.

The process solution for polymer processing according to the present disclosure contains one or more polar aprotic solvents, and two or more polar aprotic solvents may be used together, if necessary. The polar aprotic solvent swells a silicone polymer and serves to dissolve the fluorine-based compound and the decomposed silicone polymer.

The polar aprotic solvent according to the present disclosure may contain one or more selected from the group consisting of ketone-based, acetate-based, amide-based, pyridine-based, morpholine-based, pyrrolidone-based, urea-based, phosphate-based, sulfoxide-based, nitrile-based, carbonate-based, oxazolidone-based, piperazine-based, and furan-based solvents.

Meanwhile, in the case of water or alcohol-based compounds (e.g., diethylene glycol nomomethyl ether, ethylene glycol, isopropyl alcohol, etc.), which are generally known solvents, it is difficult to remove the polymer by hydrogen bonding with the fluorine ion. Therefore, it is preferable that a solvent of a process solution for polymer processing according to the present disclosure contains substantially no water and alcohol-based compounds.

The ketone-based solvent may contain a compound represented by the following Formula 7-1:

wherein R23and R24are each independently a C1-C18linear or branched aliphatic hydrocarbon group, and the sum of carbon atoms of R23and R24is preferably 2 or more and less than 30.

The pyridine-based solvent may contain a compound represented by the following Formula 7-2:

wherein R25to R27may be each independently hydrogen, a C1-C10linear or branched aliphatic hydrocarbon group, a halogen (e.g., F, Cl, Br, or I), an aldehyde group (—CHO), an acetaldehyde group (—COCH3), a C1-C4alkoxy group, a vinyl group, an acetylene group, a cyano group (—CN), or a methylsulfide group (—SCH3).

The morpholine-based solvent may contain a compound represented by the following Formula 7-3:

wherein R28is hydrogen; a C1-C6linear or branched aliphatic hydrocarbon group; a vinyl group; a cyano group (—CN); a C1-C4aliphatic hydrocarbon group substituted with a tertiary amine; a phenyl group or a pyridine group substituted with a C1-C4alkyl group, a cyano group (—CN), a halogen group (e.g., F, Cl, Br, or I) or an aldehyde group (—CHO), X is oxygen or —NR29—, and R29is a C1-C4aliphatic hydrocarbon group.

The urea-based solvent may contain a compound represented by the following Formula 7-4:

wherein X is oxygen or —NR29—, R29and R30are each independently a C1-C6linear, branched or cyclic aliphatic hydrocarbon group; or a C1-C4aliphatic hydrocarbon group substituted with a vinyl group, a phenyl group, an acetylene group, a methoxy group, or a dimethylamino group.

For example, the urea-based solvent may include, but is not limited to, tetramethylurea, tetraethylurea, or tetrabutylurea, etc.

The phosphate-based solvent may contain a compound represented by the following Formula 7-5:

wherein R31to R33are each independently a C1-C8linear or branched aliphatic hydrocarbon group; a C3-C8divalent aliphatic hydrocarbon group forming a ring together with adjacent oxygen; a phenyl group unsubstituted or substituted with a C1-C4aliphatic hydrocarbon group; a C2-C4aliphatic hydrocarbon group substituted with halogen (e.g., F, Cl, Br, or I), or a phenyl group substituted with halogen.

For example, the oxazolidone-based solvent may include, but is limited to, 2-oxazolidone, 3-methyl-2-oxazolidone, etc.

For example, the piperazine-based solvent may include, but is not limited to, dimethylpiperazine, dibutylpiperazine, etc.

The furan-based solvent may contain a compound represented by the following Formula 7-6 or 7-7:

wherein R34to R39may be each independently hydrogen; or a C1-C5linear or branched aliphatic hydrocarbon group unsubstituted or substituted with an alkoxy group, a cyano group or a halogen, or a C1-C5alkyl group substituted with an alkoxy group, a cyano group, or a halogen.

The polar aprotic solvent is contained in an amount of 66 to 99.89% by weight, preferably 70 to 99.45% by weight, based on the total weight of the process solution for polymer processing. If the polar aprotic solvent is contained in an amount of less than 66% by weight, there may be a problem in that the metal film is damaged. If the polar aprotic solvent is contained in an amount of exceeding 99.89% by weight, there may be a problem in that the silicone-based resin attached to an electronic component may not be effectively removed.

The process solution for polymer processing according to the present disclosure contains one or more fluorine-based compounds, and the fluorine-based compound serves to reduce a molecular weight by breaking a ring of the silicone polymer.

The fluorine-based compound according to the present disclosure may contain one or more compounds selected from the group consisting of alkylammonium fluoride, alkylphosphonium fluoride, and alkylsulfonium fluoride.

The alkylammonium fluoride may contain a compound represented by the following Formula 4-1 or 4-2:

wherein R9to R12are each independently an alkyl group having 3 to 10 carbon atoms. When R9to R12are an alkyl group having 2 or less carbon atoms, the solubility of the fluorine-based compound in the solvent is reduced, and thus precipitation occurs immediately after mixing, or precipitation occurs after some time has elapsed.

wherein R13to R15are each independently an alkyl group having 1 to 10 carbon atoms.

In addition, the alkylammonium fluoride may exist in the form of a hydrate, such as alkylammonium fluoride.n(H2O), where n is an integer of 5 or less. Examples of the alkylammonium fluoride may include, but is not limited to, tetra-n-butylammonium fluoride hydrate, tetra-n-butylammonium fluoride trihydrate, or benzyltrimethylammonium fluoride hydrate, etc.

In addition, the alkylphosphonium fluoride may contain a compound represented by the following Formula 5:

wherein R16to R19are each independently an aliphatic hydrocarbon having 1 to 22 carbon atoms or an aromatic hydrocarbon having 6 to 20 carbon atoms.

In addition, the alkylsulfonium fluoride may contain a compound represented by the following Formula 6:

wherein R20to R22are each independently an aliphatic hydrocarbon having 1 to 22 carbon atoms or an aromatic hydrocarbon having 6 to 20 carbon atoms.

The fluorine-based compound is contained in an amount of 0.1 to 20% by weight, preferably 0.5 to 17% by weight, based on the total weight of the process solution for polymer processing. If the fluorine-based compound is contained in an amount of less than 0.1% by weight, there may be a problem that the silicone-based resin attached to electronic parts, etc., may not be effectively removed. If the fluorine-based compound is contained in an amount of exceeding 20% by weight, the moisture content is increased over time, and damage to the metal film may increase due to a decrease in the removal performance of the silicone resin and an increase in fluoride.

The process solution for polymer processing according to the present disclosure contains one or more sulfur-containing compounds in order to reduce damage to a metal film exposed to a lower portion of the adhesive, and the sulfur-containing compound preferably includes a thiol group (—SH). In addition, the sulfur-containing compound may provide a metal anticorrosive effect without impairing a polymer removal performance of the process solution for polymer processing.

In the present disclosure, when the sulfur-containing compound deviates from the structures of Formulas 1 to 3 described later, for example, when it contains —OH or —NH—, NH2, a hydrogen bond is formed with the fluorine-based compound, so that the removal performance of the polymer is rapidly reduced, which makes it impossible to meet the purpose of the present disclosure.

The sulfur-containing compound according to the present disclosure may be a component additionally contained in addition to the polar aprotic solvent and the fluorine-based compound contained in the composition of the present disclosure.

The sulfur-containing compound may contain one or more compounds represented by any one of the following Formulas 1-1 to 3:

wherein R1is a linear or branched alkyl group having 3 to 12 carbon atoms unsubstituted or substituted with a thiol group, a cyclic hydrocarbon group having 3 to 12 carbon atoms unsubstituted or substituted with a thiol group or halogen, and the halogen is fluorine, chlorine, bromine, or iodine.

For example, the sulfur-containing compound represented by Formula 1-2 may include, but is not limited to, diethyldisulfide, dipropyldisulfide, diisopropyldisulfide, diisoamyldisulfide, diamyldisulfide, dibutyldisulfide, diisobutyldisulfide, di-tert-butyldisulfide, methylpropyldisulfide, diphenyldisulfide, didodecyldisulfide, bis(1,1,3,3-tetramethylbutyl)disulfide, or di-tert-dodecyldisulfide, etc. The sulfur-containing compound represented by Formula 1-2 may be formed by oxidation of a compound containing a thiol group (e.g., the compound represented by Formula 1-1).

wherein R2to R4and R6are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an unsaturated hydrocarbon group having 2 to 5 carbon atoms including a double bond, and R5is a direct linkage or an alkylene group having 1 to 5 carbon atoms.

For example, the sulfur-containing compound represented by Formula 2 may include, but is not limited to, (3-mercaptopropyl)trimethoxysilane, 2-(trimethylsilyl)ethanethiol, trimethyl(2-methylsulfanylethyl)silane, (3-mercaptopropyl)methyldimethoxysilane, or (ethylthio)trimethylsilane, etc.

wherein R7and R8may be connected to each other to form an alicyclic or aromatic monocyclic or polycyclic ring, and the monocyclic or polycyclic ring may include one or more hetero atoms selected from nitrogen (N), oxygen (O), or sulfur (S), and may be substituted with one or more substituents.

In addition, the sulfur-containing compound represented by Formula 3 may have a resonance structure with a sulfur atom by connecting R7and R8to each other to form a ring, and may include a thiol group due to the resonance structure.

For example, the sulfur-containing compound represented by Formula 3 may include, but is not limited to, 2-mercaptothiazoline, 2-amino-5-mercapto-1,3,4-thiadiazole, 2-mercaptobenzoxazole, or 2-mercaptobenzothiazole, etc.

The sulfur-containing compound is contained in an amount of 0.01 to 10% by weight, preferably 0.05 to 7% by weight, based on the total weight of the process solution for polymer processing. If the sulfur-containing compound is included in an amount of less than 0.01% by weight, there may be a problem that the damage to the metal film exposed to the lower portion of the adhesive may not be sufficiently suppressed. If the sulfur-containing compound is included in an amount exceeding 10% by weight, there may be a problem that the removability of the adhesive is reduced.

(D) Other Additives

In the range that does not impair the polymer removal performance of the process solution for polymer processing according to the present disclosure, the process solution for polymer processing may further include components such as corrosion inhibitors and surfactants commonly used in this field in addition to the above components.

The corrosion inhibitor is used to effectively inhibit corrosion of the metal-containing lower layer when the resin is removed, is generally commercially available from various sources, and may be used without further purification.

The surfactant may be used to enhance cleaning properties. For example, an anionic surfactant, a cationic surfactant, and a nonionic surfactant may be used, but among them, it is particularly preferable to use a nonionic surfactant having excellent wettability and less foaming, and these may be used alone or in combination of two or more.

In addition, the present disclosure provides a method for removing a polymer from a device using the process solution for polymer processing according to the present disclosure. A method of removing the polymer according to the present disclosure may be applied to all of the contents described for a process solution for polymer processing according to the present disclosure and detailed descriptions of overlapping parts are omitted, but the same may be applied even if the description is omitted.

Specifically, the method of removing the polymer is to remove a polymer such as a silicon adhesive used in the process of making a device wafer thin, and a process of making the device wafer thin includes a process of forming a silicon adhesive and a silicon release layer between a carrier wafer and a device wafer to make a semiconductor substrate thin. The silicon release layer does not cause damage to the device wafer at a location where separation occurs in the process of removing the carrier wafer after processing. The silicone adhesive bonds the device wafer and the carrier wafer and undergoes a curing process. After such a process, the cured polymer is removed using the process solution for polymer processing according to the present disclosure.

Hereinafter, the present disclosure will be described in more detail through the examples. However, the following examples are for describing the present disclosure in more detail, and the scope of the present disclosure is not limited by the following examples.

Examples 1 to 26 and Comparative Examples 1 to 5: Preparation of Process Solutions for Polymer Processing

A process solution for polymer processing was prepared according to the components and composition ratios shown in Tables 1 and 2 below.

The fluorine-based compounds used in Tables 1 and 2 are as follows.

Experimental Example 1: Evaluation of Removability of Thin Film Substrate—Network Polymer

A wafer on which a cured silicone polymer was coated at a thickness of 50 μm and which was cut into a size of 2×2 cm2was used, and the prepared sample was immersed in a composition solution at 25° C. for 1 minute while rotating the composition solution at 400 rpm, washed with isopropyl alcohol (IPA), and then dried. After evaluation, a thickness of the film of the cured silicone polymer was measured by SEM. Then, by measuring a film thickness of the remaining silicone-based resin was measured by a scanning electron microscope (SEM), the removal rate was calculated and summarized in Tables 3 and 4 below.

Removal rate (μm/min)=[Thickness before evaluation (μm)−Thickness after evaluation (μm]/Evaluation time (min)

Experimental Example 2: Evaluation of Removability of Thin Film Substrate Linear PDMS

A silicon wafer on which a blend obtained by mixing a polydimethylsiloxane prepolymer and a curing agent in a predetermined mass ratio was spin-coated and which was cut into a size of 2×2 cm2was used, and the prepared sample was immersed in a composition solution at 25° C. for 1 minute while rotating the composition solution at 400 rpm, washed with IPA and then dried. After evaluation, the residues on the wafer surface were observed by an optical microscope and SEM. The presence/absence of residues is shown in Tables 3 and 4 below according to the following criteria.

O: Absence of residue

X: Presence of residue

Experimental Example 3: Metal Damage Evaluation 1

A wafer on which 1011 bump balls composed of Sn, Sn/Ag alloy, Sn/Au alloy, Sn/Ag/Cu alloy, etc., were formed and which was cut into a size of 2×2 cm2was used, and the prepared sample was immersed for 30 minutes while rotating a composition solution at 25° C. at 400 rpm, washed with IPA and then dried. After evaluation, the number of bump ball damage was confirmed by SEM, and the number of occurrences was summarized in Tables 3 and 4 below.

Experimental Example 4: Metal Damage Evaluation 2

In addition, a wafer on which an aluminum thin film was formed and which was cut into a size of 2×2 cm2was used, and the prepared sample was immersed for 30 minutes while rotating the composition solution at 25° C. at 400 rpm, washed with IPA and then dried. In addition, after evaluation, pad defects were confirmed by an optical microscope, and the results according to the following evaluation criteria are summarized in Tables 3 and 4 below.

O: No change in surface morphology and no discoloration

Referring to Tables 3 and 4, it can be seen that the process solutions for polymer processing of Examples 1 to 26 according to the present application contains a sulfur-containing compound, and thus the removability to silicon-based network polymers and linear polymers was excellent, and the damage to the metal was significantly reduced. In particular, it can be seen that among the sulfur-containing compounds, in the case of Examples 1 to 23 using a sulfur-containing compound satisfying the structures of Formulas 1-1 to 3, the polymer removal ability was excellent, the bump ball damage was 5 or less or did not occur at all, and the Al damage did not occur, so the metal damage prevention effect was more excellent.

Meanwhile, it was seen that in Comparative Example 2 in which only a fluorine-based compound was used without a polar aprotic solvent, polymer removal was impossible, even if the fluorine-based compound and the polar aprotic solvent were contained, when the sulfur-containing compound was not used or other additives were used, the number of bump ball damage was significantly increased, and there was also damage to the aluminum.