JP2012033788A - Machining and peeling method of planar article to be ground - Google Patents

Abstract

【Task】
[Problems to be solved by the invention]
An object of the present invention is to provide a method for fixing a wafer that can be stably processed without cracking or chipping when a plate-like workpiece such as a wafer is thinned by a method such as grinding or polishing.
[Solution]
That is, the present invention relates to a method for reducing the thickness of a plate-shaped workpiece by grinding and polishing, in which the main surface is an adhesive tape, the side surface (peripheral portion) is (A) polyfunctional (meth) acrylate, and (B) monofunctional. It is characterized by fixing with an ultraviolet curable adhesive of an acrylic resin composition comprising (meth) acrylate and (C) a polymerization initiator.
[Selection figure] None

Description

The present invention relates to a wafer fixing method that can be stably processed without cracking or chipping when a plate-like workpiece such as a wafer is thinned by a method such as grinding or polishing.

Conventionally, a plate-like material such as a silicon wafer or a sapphire wafer is processed to a thickness suitable for mounting by reducing the thickness with a grindstone after a desired surface processing. However, with the miniaturization of electronic devices, for example, the finished thickness of silicon wafers has been reduced, causing a problem of cracking during or after processing. In addition, the sapphire wafer has a problem that the substrate breaks during grinding due to distortion.

In order to improve such a problem, a method is known in which a workpiece is fixed with wax and is ground and polished (Patent Document 1). However, it takes a lot of labor for cleaning and has a large environmental load. In order to solve this problem, UV curable adhesives that can be peeled into a film with UV rays are also known. However, it is difficult to ensure the thickness accuracy of the paste while high finish thickness accuracy is required. It was.

Patent Document 1 Patent 2767196 (Nichika Seiko)

An object of the present invention is to provide a method for fixing a wafer that can be stably processed without cracking or chipping when a plate-like workpiece such as a wafer is thinned by a method such as grinding or polishing.

Therefore, as a result of intensive studies, the present inventors have developed a wafer fixing method that can be stably processed without cracking or chipping when a plate-like workpiece such as a wafer is thinned by a method such as grinding or polishing. It came to do.

That is, the present invention
In a method of reducing the thickness of a plate-like workpiece by grinding and polishing, the main surface of the plate-like workpiece is an adhesive tape, the side surface (outer peripheral portion) is (A) a polyfunctional (meth) acrylate, (B) It is a processing method characterized by fixing with an ultraviolet curable adhesive of an acrylic resin composition comprising a monofunctional (meth) acrylate and (C) a polymerization initiator, and more preferably (A) 1 to 50 Parts by mass, (B) 5 to 95 parts by mass, and (C) 0.1 to 20 parts by mass.

In another invention, the main surface of the plate-shaped workpiece is an adhesive tape, the side surface (peripheral portion) is (A) polyfunctional (meth) acrylate, (B) monofunctional (meth) acrylate, and (C) polymerization initiation An acrylic resin composition composed of an agent is fixed with an ultraviolet curable adhesive and processed by grinding and polishing, and then the workpiece is fixed by irradiating with ultraviolet rays. It is a peeling method, More preferably, (A) 1-50 mass parts, (B) 5-95 mass parts, (C) 0.1-20 mass parts is contained.

As the (A) polyfunctional (meth) acrylate used for the ultraviolet curable adhesive, two or more (meth) acryloylated polyfunctional (meth) acrylate oligomers / polymers and two oligomers / polymer terminals or side chains are used. Monomers having the above (meth) acryloyl groups can be used.

(A) The polyfunctional (meth) acrylate is more preferably hydrophobic. However, in the case of water-solubility, the cured product of the resin composition swells during grinding, which may cause misalignment and poor processing accuracy. Even if it is hydrophilic, it can be used as long as the cured product of the composition is not greatly swollen or partially dissolved by water.

(A) As a polyfunctional (meth) acrylate oligomer / polymer, for example, 1,2-polybutadiene-terminated urethane (meth) acrylate, its hydrogenated product, 1,4-polybutadiene-terminated urethane (meth) acrylate, polyisoprene end ( Examples thereof include (meth) acrylate, polyester-based urethane (meth) acrylate, polyether-based urethane (meth) acrylate, polyester (meth) acrylate, and bis A type epoxy (meth) acrylate.

As bifunctional (meth) acrylate monomers, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexadiol di (meth) acrylate, 1,9-nonane Diol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, 2-ethyl-2-butyl-propanediol (meth) acrylate, neopentyl glycol modified trimethylolpropane di ( (Meth) acrylate, stearic acid-modified pentaerythritol diacrylate, polypropylene glycol di (meth) acrylate, 2,2-bis (4- (meth) acryloxydiethoxyphenyl) propane, 2,2-bis (4- (meta ) Acryloxypropoxy Phenyl) propane, 2,2-bis (4- (meth) acryloxytetraethoxyphenyl) propane, etc., and trifunctional (meth) acrylate monomers include tomethylolpropane tri (meth) acrylate, tris [(meta ) Acryloylethyl] isocyanurate, etc., and the tetrafunctional or higher (meth) acrylate monomers include dimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol ethoxytetra (meth) acrylate. , Dipentaerystol penta (meth) acrylate, dipentaerystol hexa (meth) acrylate, and the like.

The addition amount of (A) used in the acrylic resin composition is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass in 100 parts by mass of the total amount of (A) and (B). If it is 1 part by mass or more, the peelability does not deteriorate, and it can be recovered integrally with the adhesive tape at the time of peeling the adhesive tape while having the shape applied by the cured acrylic resin composition. Moreover, if it is 50 mass parts or less, hardening shrinkage will become large too much and initial adhesiveness will not fall.

(B) Monofunctional (meth) acrylate monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate , Isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclo Pentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, methoxylated cyclodecatriene (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxy Propyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, glycidyl (meth) acrylate , Caprolactone-modified tetrahydrofurfuryl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, t-butyl Aminoethyl (meth) acrylate, ethoxycarbonylmethyl (meth) acrylate, phenol ethylene oxide modified acrylate, phenol (ethylene oxide 2 mol modified) acrylate, Nord (ethylene oxide 4 mol modified) acrylate, paracumylphenol ethylene oxide modified acrylate, nonylphenol ethylene oxide modified acrylate, nonylphenol (ethylene oxide 4 mol modified) acrylate, nonylphenol (ethylene oxide 8 mol modified) acrylate, nonylphenol (propylene oxide 2. 5 mol modified) acrylate, 2-ethylhexyl carbitol acrylate, ethylene oxide modified phthalic acid (meth) acrylate, ethylene oxide modified succinic acid (meth) acrylate, trifluoroethyl (meth) acrylate, acrylic acid, methacrylic acid, maleic acid, Fumaric acid, ω-carboxy-polycaprolactone mono (meth) acrylate, phthalic acid monohydroxy ester Le (meth) acrylate, (meth) acrylic acid dimer, beta-(meth) acryloyloxyethyl hydrogen succinate, n-(meth) acryloyloxy alkyl hexahydrophthalimide and the like.

(B) The monofunctional (meth) acrylate is more preferably a hydrophobic one as in (A), and if it is water-soluble, the resin composition hardens when it is swelled during grinding and causes a displacement. Processing accuracy may be inferior. Even if it is hydrophilic, it can be used if the cured product of the resin composition does not swell or partially dissolve with water.

The addition amount of (B) used in the acrylic resin composition is preferably 5 to 95 parts by mass and more preferably 10 to 80 parts by mass in 100 parts by mass of the total amount of (A) and (B). If it is 5 parts by mass or more, the initial adhesiveness can be sufficiently obtained, and if it is 95 parts by mass or less, sufficient peelability can be obtained, and the cured acrylic resin composition can be obtained as it is applied.

(C) As the polymerization initiator, those which are sensitized with visible light or ultraviolet actinic rays to promote photocuring of the resin composition are preferred. Specifically, benzophenone and its derivatives, benzyl and its Derivatives, enthraquinone and derivatives thereof, benzoin derivatives such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, acetophenone derivatives such as diethoxyacetophenone, 4-t-butyltrichloroacetophenone, 2-dimethylaminoethyl benzoate, p-dimethylaminoethyl benzoate, diphenyl disulfide, thioxanthone and derivatives thereof, camphorquinone, 7,7-dimethyl-2,3-dioxobisic [2.2.1] Heptane-1-carboxylic acid, 7,7-dimethyl-2,3-dioxobicyclo [2.2.1] heptane-1-carboxy-2-bromoethyl ester, 7,7- Dimethyl-2,3-dioxobicyclo [2.2.1] heptane-1-carboxy-2-methyl ester, 7,7-dimethyl-2,3-dioxobicyclo [2.2.1] heptane-1 -Camphorquinone derivatives such as carboxylic acid chloride, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpho Α-aminoalkylphenone derivatives such as linophenyl) -butanone-1, benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine Examples thereof include acylphosphine oxide derivatives such as oxide, benzoyldiethoxyphosphine oxide, 2,4,6-trimethylbenzoyldimethoxyphenylphosphine oxide, and 2,4,6-trimethylbenzoyldiethoxyphenylphosphine oxide. A photoinitiator can be used 1 type or in combination of 2 or more types.

As for the addition amount of (C) used by the said acrylic resin composition, 0.1-20 mass parts is preferable with respect to 100 mass parts of total amounts of (A) and (B), and 3-20 mass parts Is more preferable. The effect of accelerating curing can be obtained at 0.1 parts by mass or more, and a sufficient curing rate can be obtained at 20 parts by mass or less.

The acrylic resin composition in the present embodiment contains A) a polyfunctional (meth) acrylate, (B) a monofunctional (meth) acrylate, and (C) a polymerization initiator. The acrylic resin composition can be blended with other materials within a range that does not impair the effects of the invention. Examples thereof include resins having a cyclopentadiene skeleton, polar organic solvents, polybutadiene; polyisoprene; hydrogenated polybutadiene polyisoprene, and inorganic fillers.

As the pressure-sensitive adhesive used for the pressure-sensitive adhesive tape, pressure-sensitive adhesives such as acrylic polymers and elastomers can be used. Moreover, when making this adhesive layer exhibit an ultraviolet curing effect, an ultraviolet curable compound or an ultraviolet curing initiator is added.

As the ultraviolet curable compound, specifically, a functional ultraviolet curable product having two or more functional groups may be used. For example, acrylate compounds, urethane acrylates, urethane acrylate oligomers and / or monomers, epoxy acrylates, polyesters There are single or mixed systems such as acrylate.

Examples of the acrylate compound include trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, or 1,4-butylene glycol. Examples include diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, and oligoester acrylate.

Examples of the urethane acrylate include polyester urethane acrylate, polyether urethane acrylate, and polyfunctional urethane acrylate.

The urethane acrylate oligomer is an ultraviolet curable compound having at least two carbon-carbon double bonds. For example, a polyol compound such as a polyester type or a polyether type and a polyvalent isocyanate compound such as (2,4 Terminal obtained by reacting tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc. Acrylate or methacrylate having hydroxyl group on isocyanate urethane prepolymer (for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene) Recall acrylate include those obtained by reacting a polyethylene glycol methacrylate).

As a method for producing the pressure-sensitive adhesive tape, there is a method in which a pressure-sensitive adhesive layer is laminated on a substrate to form a pressure-sensitive adhesive sheet, and there are a method for applying a pressure-sensitive adhesive and a method for printing. As a method for applying the pressure-sensitive adhesive, for example, there is a method in which the pressure-sensitive adhesive is directly or indirectly applied onto the substrate with a coater such as a gravure coater, comma coater, bar coater, knife coater, die coater or roll coater. As a printing method, there are convex plate printing, concave plate printing, flat plate printing, flexographic printing, offset printing, and screen printing.

As a fixing method when a plate-like workpiece such as a wafer fixed by the method of the present invention is set in a processing apparatus such as grinding / polishing, suction fixing by air suction of the apparatus, an adhesive and an adhesive tape, an adhesive There is fixing by wax or the like, but suction fixing by air suction is desirable from the viewpoint of the cost of the process and the material used and the post-treatment.

The embodiment according to the present invention and the wafer back grinding method will be described in detail.
The main formulation and results of the examples are shown in Table 1.

Example 1
Adhesive tape made by applying UV curable adhesive to PET base film is bonded to an 8-inch silicon wafer (725 μm thick), and 5 parts by mass of polyfunctional acrylate and 95 parts by mass of monofunctional acrylate are started on the outer periphery. A sample was prepared by applying an ultraviolet curable adhesive consisting of 5 parts by mass of the agent and fixing the work piece by irradiation with ultraviolet rays, and then the wafer was ground to 75 μm. Further, the cured adhesive layer on the outer periphery of the wafer was collected in a state of being integrated with the tape when the adhesive tape was peeled off.

(Example 2)
A 6-inch sapphire wafer (1300 μm thick) was bonded with an adhesive tape formed by applying an ultraviolet curable adhesive to a PET substrate film in the same manner as in Example 1, and an ultraviolet curable adhesive was applied to the outer periphery of the sample. Then, the wafer was ground to 75 μm. Here, the same adhesive tape and adhesive as in Example 1 were used.

(Example 3)
An adhesive tape formed by applying a UV curable adhesive to a PET base film is bonded to an 8-inch silicon wafer (725 μm thick) in the same manner as in Example 1, and 20 parts by mass of a polyfunctional acrylate and a monofunctional acrylate are attached to the outer periphery. A sample was prepared by applying an ultraviolet curable adhesive comprising 80 parts by mass and 10 parts by mass of a polymerization initiator, and then the wafer was ground to 75 μm. Here, the same adhesive tape as in Example 1 was used.

Example 4
A 6-inch sapphire wafer (1300 μm thick) was bonded with an adhesive tape formed by applying an ultraviolet curable adhesive to a PET substrate film in the same manner as in Example 1, and an ultraviolet curable adhesive was applied to the outer periphery of the sample. Then, the wafer was ground to 75 μm. Here, the same adhesive tape as in Example 1 and the same adhesive as in Example 3 were used.

The experiment which changed the composition of the ultraviolet curable adhesive using the 6-inch sapphire wafer similarly to Examples 2 and 4 was conducted (Examples 5 to 10). The procedure of the experiment is as described above. Here, the same adhesive tape as in Example 1 was used.

(Comparative Example 1)
An adhesive tape formed by applying an ultraviolet curable adhesive to a PET base film was bonded to an 8-inch silicon wafer (725 μm thick), and then the wafer was ground to 75 μm. Here, the same adhesive tape as in Example 1 was used.

(Comparative Example 2)
After a 6 inch sapphire wafer (1300 μm thick) was bonded with an adhesive tape obtained by applying an ultraviolet curable adhesive to a PET base film in the same manner as in Example 1, the wafer was ground to 75 μm. Here, the same adhesive tape as in Example 1 was used.

(Comparative Example 3)
After fixing an 8-inch silicon wafer (725 μm thick) with wax, the wafer was ground to 75 μm.

(Comparative Example 4)
After fixing a 6 inch sapphire wafer (1300 μm thick) with wax, the wafer was ground to 75 μm.

(Evaluation)
In Example 1 to Comparative Example 4, after 10 wafers were ground, the following items were evaluated.
(Wafer cracking)
Confirmation of the number of wafers with cracks (chipping on the outer periphery)
Excellent: Chipping was less than 1 μm.
Good: Chipping was 1 μm or more and less than 3 μm.
Impossible: The chipping was 3 μm or more.
(With or without residue)
After grinding, the fixed surface of the wafer was observed with a microscope to confirm the number of wafers with residues.

In this example, even when the back surface of the wafer was ground by the fixing method of Example 1 to Example 7, both the grindability (cracking and chipping) and the residue were satisfactory. About Example 8 to Example 10, although it was different in comparison with Example 1 to Example 7, it was a usable range. The wafer fixing methods of Comparative Example 1 to Comparative Example 4 cannot be employed in the evaluation shown in Table 1.

Claims (4)

In a method of thinning a plate-like workpiece by grinding and polishing, the main surface of the plate-like workpiece is an adhesive tape, the side surface (outer peripheral portion) is (A) a polyfunctional (meth) acrylate, (B And a fixing method using an ultraviolet curable adhesive of an acrylic resin composition containing a monofunctional (meth) acrylate and (C) a polymerization initiator. The main surface of the plate-shaped workpiece contains an adhesive tape, the side surface (peripheral part) contains (A) polyfunctional (meth) acrylate, (B) monofunctional (meth) acrylate, and (C) a polymerization initiator. A method for peeling a workpiece, comprising fixing an acrylic resin composition with an ultraviolet curable adhesive, grinding and polishing, and then irradiating ultraviolet rays to remove the workpiece. . (A) 1-50 mass parts, (B) 5-95 mass parts, (C) The processing method of Claim 1 which is 0.1-20 mass parts. (A) 1-50 mass parts, (B) 5-95 mass parts, (C) 0.1-20 mass parts, The peeling method of Claim 2.