WO2011078193A1

WO2011078193A1 - Adhesive tape for protecting surface of semiconductor wafer

Info

Publication number: WO2011078193A1
Application number: PCT/JP2010/073054
Authority: WO
Inventors: 啓時横井; 祥文岡; 正三矢野
Original assignee: 古河電気工業株式会社
Priority date: 2009-12-22
Filing date: 2010-12-21
Publication date: 2011-06-30
Also published as: TW201124503A; JP2011151355A; JP4851613B2; KR20120066685A; KR101230736B1; TWI465541B; CN102754200A; CN102754200B

Abstract

An adhesive tape for protecting the surface of a semiconductor wafer comprises a substrate resin film and an adhesive layer directly on the substrate resin film with an intermediate resin layer, in which base resin components containing an acrylic polymer and/or polyurethane acrylate are cross-linked, interposed therebetween. The repulsion coefficient (γ) obtained by dividing repulsion force (α) per unit width, which is found from the load of loop stiffness obtained by measuring the adhesive tape for protecting the surface of the semiconductor wafer under a specific condition, by the square of the thickness (β) of a substrate is 100 mN/mm³ or more, the repulsion force (α) is 13 mN/mm or less, and the difference between tensile fracture elongations in a longitudinal direction and a lateral direction is 35% or less.

Description

Adhesive tape for semiconductor wafer surface protection

The present invention relates to an adhesive tape for protecting a semiconductor wafer surface. More specifically, the present invention relates to a semiconductor wafer surface protecting adhesive tape used when grinding a semiconductor wafer into a thin film.

A semiconductor package is manufactured by slicing a high-purity silicon single crystal or the like into a semiconductor wafer, and then forming an integrated circuit on the wafer surface by ion implantation, etching, or the like. By grinding and polishing the back surface of the semiconductor wafer on which the integrated circuit is formed, the semiconductor wafer has a desired thickness. At this time, in order to protect the integrated circuit formed on the surface of the semiconductor wafer, an adhesive tape for protecting the surface of the semiconductor wafer is used. The back-ground semiconductor wafer is stored in a wafer cassette after the back-side grinding is completed, transported to a dicing process, and processed into semiconductor chips.

Conventionally, the thickness of a semiconductor wafer has been reduced to about 200 to 400 μm by backside grinding. However, with the recent progress of high-density mounting technology, it is necessary to reduce the size of the semiconductor chip, and the thickness of the semiconductor wafer is being reduced. Depending on the type of semiconductor chip, it is necessary to reduce the thickness to about 100 μm. In addition, in order to increase the number of semiconductor chips that can be manufactured by one processing, the diameter of the wafer tends to be increased. Until now, wafers with diameters of 5 inches and 6 inches have been mainstream, but in recent years, processing of semiconductor chips from semiconductor wafers with diameters of 8 to 12 inches has become the mainstream.
The trend of thinning and increasing the diameter of semiconductor wafers has shown a remarkable tendency, particularly in the field of flash memory where NAND type and NOR type exist, and in the field of DRAM, which is a volatile memory. For example, it is not uncommon to grind to a thickness of 150 μm or less using a semiconductor wafer having a diameter of 12 inches. When a large-diameter semiconductor wafer is ground to a thin thickness, the rigidity of the wafer is lowered and warpage is likely to occur.

Usually, a semiconductor wafer is taken out one by one from a dedicated case called a wafer cassette by a robot arm, held by a semiconductor wafer fixing jig in a grinding machine, and backside grinding is performed. The back-ground semiconductor wafer is stored in a wafer cassette by a robot arm and transferred to the next process. When the semiconductor wafer is warped when held by the semiconductor wafer fixing jig, the semiconductor wafer may not be adsorbed well, or in the worst case, the semiconductor wafer may be damaged. Further, when the semiconductor wafer is warped when stored in the wafer cassette, there is a problem that the robot arm comes into contact with the semiconductor wafer after storage and damages the semiconductor wafer.

Therefore, an apparatus (in-line apparatus) has been proposed in which a thin wafer after grinding is not stored in a wafer cassette but is collectively performed from the back surface grinding process to the dicing tape mounting process. In addition, methods have been proposed that are less susceptible to the effects of wafer warping due to improved performance of wafer fixing jigs and robot arms.

On the other hand, a method for reducing the warpage of the semiconductor wafer by reducing the stress applied to the semiconductor wafer when the semiconductor wafer surface protecting adhesive tape is bonded to the semiconductor wafer has been proposed. For example, in Patent Document 1, a base material in which a rigid film and a stress relaxation film are laminated via a peelable adhesive layer, and an adhesive layer provided on the stress relaxation film of the base material An adhesive sheet for processing semiconductor wafers has been proposed.
Moreover, in patent document 2, the adhesive sheet for a process which has an intermediate | middle layer which has the storage elastic modulus of a specific range between a base material and an adhesive layer is proposed, and in patent document 3, a base film consists of at least 3 layers. Thus, an adhesive film for protecting a semiconductor wafer has been proposed in which the storage elastic modulus of the outermost and innermost layers of the base film is within a specific range. Further, Patent Document 4 proposes a multilayer sheet in which specific materials are laminated.
However, when using the semiconductor wafer surface protecting adhesive tape of Patent Document 1, after the semiconductor wafer processing, the interface between the peelable adhesive layer and the rigid film, the peelable adhesive layer and the stress relaxation property A complicated process of peeling at the interface with the film or inside the layer constituting the peelable adhesive layer is required. Further, the pressure-sensitive adhesive layer and the stress relaxation layer are stacked in layers, and the cushioning property is excessive. Therefore, when a semiconductor wafer is ground to a thickness of 50 μm or less, there is a high possibility of causing wafer cracks.
Moreover, when the adhesive sheet for semiconductor wafer protection of the adhesive sheet for semiconductor wafer processing of patent document 2 is bonded to the semiconductor wafer in which the polyimide film was formed, and the back surface grinding of the semiconductor wafer was performed, the thickness of the semiconductor wafer was When the thickness is less than 100 μm, the insulating film coated on the surface of the semiconductor wafer contracts, and the semiconductor wafer itself may warp. In this case, there is a problem that the semiconductor wafer falls when the semiconductor wafer is held on the wafer fixing jig.
Furthermore, when the adhesive sheet for semiconductor wafer processing of Patent Document 3 is bonded to a semiconductor wafer on which a polyimide film is formed and the backside grinding of the semiconductor wafer is performed, there is no problem with respect to the point of transporting the wafer with the adhesive sheet. When a semiconductor wafer is ground to a thin film having a thickness of 50 μm or less, edge cracks or wafer cracks may occur.

JP 2003-261842 A JP 2004-107644 A JP 2002-69396 A JP 2006-264296 A

The present invention provides an adhesive tape for protecting a semiconductor wafer surface, which can be formed into a thin film, for example, a thin film wafer having a thickness of 100 μm or less, even if the back surface of the wafer is ground while the adhesive tape for protecting a semiconductor wafer surface is bonded to the semiconductor wafer. The issue is to provide.

The present inventors diligently studied the above problems. As a result, a semiconductor wafer having a base resin film and an adhesive layer directly through an intermediate resin layer in which a base resin component containing an acrylic polymer and / or polyurethane acrylate is crosslinked on the base resin film A surface protection adhesive tape having a repulsive force α and a restitution coefficient γ per unit width determined from a load load of a loop stiffness obtained by measuring the semiconductor wafer surface protection adhesive tape under specific conditions in a specific range. It was found that a pressure-sensitive adhesive tape for protecting a semiconductor wafer surface in which the difference between the tensile elongation at break in the machine direction and the transverse direction is not more than a specific value can solve the above problems. The present invention has been made based on this finding.

That is, the present invention provides the following inventions.
<1> A semiconductor wafer having a pressure-sensitive adhesive layer directly through a base resin film and an intermediate resin layer in which a base resin component containing an acrylic polymer and / or polyurethane acrylate is crosslinked on the base resin film A surface protective adhesive tape, which is obtained by applying a repulsive force α per unit width obtained from a load load of loop stiffness measured on the semiconductor wafer surface protective adhesive tape under the following conditions (a) to (d): The restitution coefficient γ divided by the square of the thickness β of the material is 100 mN / mm ³ or more, the repulsion force α is 13 mN / mm or less, and the difference between the tensile breaking elongation in the longitudinal direction and the transverse direction is 35% or less. An adhesive tape for protecting a surface of a semiconductor wafer.
(A) Equipment Loop step tester (trade name, manufactured by Toyo Seiki Co., Ltd.)
(B) Loop (test piece) shape Length 50 mm or more, width 10 mm
(C) Indenter pushing speed 3.3 mm / sec
(D) Indentation amount of indenter 5 mm from the point of contact of the indenter with the loop <2> The acrylic polymer of the intermediate resin layer has a hydroxyl group and a carboxyl group, for protecting a semiconductor wafer surface according to <1> Adhesive tape.
<3> The adhesive tape for protecting a semiconductor wafer surface according to <1>, wherein the polyurethane acrylate of the intermediate resin layer has a hydroxyl group and a carboxyl group.
<4> The adhesive tape for protecting a semiconductor wafer surface according to any one of <1> to <3>, wherein the glass transition temperature after crosslinking of the intermediate resin layer is −10 ° C. to 30 ° C.
<5> The adhesive tape for protecting a semiconductor wafer surface according to any one of <1> to <4>, wherein the base resin film is a polyester resin film.
<6> The adhesive tape for protecting a semiconductor wafer surface according to <5>, wherein the polyester resin film is a polyethylene terephthalate film.
<7> The adhesive tape for protecting a semiconductor wafer surface according to <5> or <6>, wherein the polyester resin film has a thickness of 25 to 75 μm.
<8> The adhesive tape for protecting a semiconductor wafer surface is a pressure-sensitive adhesive tape, has an adhesive strength to a SUS polished surface at 20 to 25 ° C. of 0.5 N / 25 mm or more, and has an adhesive strength to a SUS polished surface at 50 ° C. The adhesive tape for protecting a semiconductor wafer surface according to any one of <1> to <7>, wherein the adhesive tape is 0.5 N / 25 mm or less.
<9> The adhesive tape for protecting a semiconductor wafer surface according to <8>, wherein the weight average molecular weight of the base resin constituting the pressure-sensitive adhesive layer is 1,000,000 or more.
<10> The adhesive tape for protecting a surface of a semiconductor wafer according to any one of <1> to <7>, wherein the adhesive layer has low adhesive strength when irradiated with radiation.
<11> A base resin whose main component is a polymer in which the pressure-sensitive adhesive layer contains, as a constituent unit, an acrylic monomer having at least one radiation-polymerizable carbon-carbon double bond-containing group with respect to the main chain. The adhesive tape for surface protection of a semiconductor wafer according to <10>, wherein the tape is used.

Even when the semiconductor wafer surface protecting adhesive tape of the present invention is bonded to the semiconductor wafer surface and the back surface of the wafer is ground to form a thin film wafer of 100 μm or less, the warpage of the semiconductor wafer can be reduced. it can. For this reason, the drop mistake at the time of wafer conveyance by the curvature of a semiconductor wafer can be reduced, and it can implement without trouble until the dicing tape and dicing die-bonding film mounting which are a post process, and exfoliation of surface protection tape. The adhesive tape for protecting the surface of a semiconductor wafer of the present invention can be used for semiconductor wafer processing that requires thin film grinding, such as DRAM and NAND flash.

The above and other features and advantages of the present invention will become more apparent from the following description with reference to the accompanying drawings as appropriate.

FIG. 1 is a cross-sectional view showing an embodiment of the adhesive tape for protecting a semiconductor wafer surface according to the present invention.

A preferred semiconductor wafer surface protecting adhesive tape of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view showing a preferred embodiment of the adhesive tape for protecting a semiconductor wafer surface of the present invention. As can be seen from FIG. 1, the base resin film 1 and the pressure-sensitive adhesive layer 2 are formed on the base resin film 1 via the intermediate resin layer 3.

The semiconductor wafer surface protective adhesive tape of the present invention can suppress the amount of warpage of a semiconductor wafer even when a semiconductor wafer with an insulating film such as polyimide is ground to a thin film. Usually, an insulating film such as polyimide is formed on the surface of a semiconductor wafer by about several μm. Since the insulating film is often cross-linked by heating or the like, residual stress may exist in the insulating film on the surface of the semiconductor wafer. However, before the backside grinding of the semiconductor wafer, the semiconductor wafer is thick and rigid so that the semiconductor wafer does not warp due to residual stress. However, as the semiconductor wafer is thinly ground, the rigidity of the semiconductor wafer itself decreases. Along with this, a phenomenon occurs in which the residual stress due to thermal shrinkage or the like when the insulating film such as a polyimide film is crossed exceeds the rigidity of the semiconductor wafer and the semiconductor wafer itself warps. When the semiconductor wafer surface protective adhesive tape of the present invention is bonded to the wafer surface and ground, the adhesive tape of the present invention exhibits a warp correction rate exceeding the residual stress of the insulating film, and after grinding. The warpage of the semiconductor wafer can be reduced.

The adhesive tape for protecting the surface of a semiconductor wafer according to the present invention is peeled off after grinding the back surface of the semiconductor wafer. The adhesive tape for protecting the surface of a semiconductor wafer of the present invention has a restitution coefficient γ obtained by dividing the repulsive force α per unit width by the square of the thickness β of the substrate, which is determined from the loop stiffness measured under the following conditions, of 100 N / mm. ³ or more, the repulsive force α is 18 N / mm or less, and the difference in tensile breaking elongation between the longitudinal direction and the transverse direction is 35% or less.
If the coefficient of restitution is within this range, the adhesive tape for protecting a semiconductor wafer surface of the present invention can be wound up in a roll shape. If the coefficient of restitution γ is too small, it is not preferable because the force for correcting the warpage of the wafer itself is small. On the other hand, if the repulsive force α is too large, the rigidity of the tape becomes too strong, and the tape itself is difficult to bend when the tape is peeled off, and the wafer after thin film grinding is liable to break, which is not preferable. The repulsive force α is 18 N / mm or less to obtain good peeling performance, preferably 10 N / mm or less, and more preferably 8 N / mm or less. The repulsive force α is preferably 1 N / mm or more from the viewpoint of suppressing deflection.
Moreover, even if the adhesive tape for protecting the semiconductor wafer surface has rigidity capable of suppressing warpage of the semiconductor wafer after grinding, if the adhesive tape itself warps, the semiconductor wafer to which the adhesive tape is bonded is warped. It becomes. In this case, a transport error may occur when the semiconductor wafer is transported while the adhesive tape is bonded, or the edge portion of the semiconductor wafer may be warped. As a result, when the semiconductor wafer is ground, the wafer may flutter and cause edge chipping or edge cracks. Therefore, in order to suppress the warpage of the semiconductor wafer surface protecting adhesive tape itself, the difference between the tensile breaking elongation in the longitudinal direction and the transverse direction is set to 35% or less. Thereby, the curvature of adhesive tape itself can be reduced.

The loop stiffness in the present invention is an index for evaluating the restitution coefficient and repulsion force of a tape-shaped test piece. The loop stiffness can be obtained from the load applied to the indenter when the semiconductor wafer surface protecting adhesive tape of the present invention is formed into a loop shape and the loop-shaped test piece is pressed with the indenter and the loop is deformed.
The loop stiffness in the present invention can be measured using, for example, a loop stiffness tester (trade name, manufactured by Toyo Seiki Co., Ltd.). The loop stiffness is measured under the following conditions (a) to (c).
(A) Loop (test piece) shape 50 mm or more in length and 10 mm in width
(B) Indenter pushing speed 3.3 mm / sec
(C) Pushing amount of indenter Push in 5 mm from the time when the indenter comes into contact with the loop. The repulsive force α of the semiconductor wafer surface protecting adhesive tape in the present invention is the load load obtained by (c) described above per width of the test piece. It means the converted one. The restitution coefficient γ of the semiconductor wafer surface protecting adhesive tape is a value obtained by dividing the repulsion force α by the square of the base resin film of the test piece.

As shown in FIG. 1, the adhesive tape 20 for protecting a semiconductor wafer surface of the present invention has a specific intermediate resin layer 3 described later between a base resin film 1 and an adhesive layer 2. Further, a release film (not shown) may be laminated on the pressure-sensitive adhesive layer 2.
The adhesive tape for protecting a semiconductor wafer surface of the present invention shown in FIG. 1, for example, applies an intermediate resin layer obtained by applying a composition constituting the intermediate resin layer 2 on a release film and drying it onto the base film 1. The intermediate resin layer 3 is formed by transferring the intermediate resin layer composition directly onto the base resin film 1, and then the adhesive layer 2 is similarly transferred onto the intermediate resin layer 3. It can be produced by direct application.

As the base resin component of the intermediate resin layer composition, an acrylic polymer can be used from the viewpoint of heat resistance. Examples of the acrylic polymer include the following (meth) acrylic acid ester monomers and (meth) acrylic acid cycloalkyl esters as constituent components. Examples of the (meth) acrylic acid alkyl ester used as the monomer include methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester, Isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester, tridecyl ester, tetradecyl ester, hexadecyl ester , Octadecyl esters, eicosyl esters, benzyl esters, etc., (meth) alkyl esters having 1 to 30 carbon atoms, particularly 1 to 18 carbon atoms. . Examples of the (meth) acrylic acid cycloalkyl ester used as the monomer include cyclopentyl ester and cyclohexyl ester. An acrylic polymer using one or more of these monomers as a constituent component can be used as the base resin component of the intermediate resin component. In particular, n-butyl methacrylate (n-BMA) is preferable from the viewpoint of improving flexibility due to an increase in the distance between cross-linking points. These (meth) acrylic acid ester monomers are preferably used as the main constituent (for example, 90 to 100%) in the acrylic polymer.

As an acrylic polymer used as a base resin component of the intermediate resin layer composition, an acrylic copolymer containing as a constituent component another monomer copolymerizable with the (meth) acrylic acid alkyl ester or cycloalkyl ester. Can be mentioned. For example, one or more of the following monomers can be used.
(1) Carboxyl group-containing monomers Carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid (2) acid anhydride single monomer Forms Anhydride monomer such as maleic anhydride, itaconic anhydride (3) Hydroxy-containing monomer (2-hydroxyethyl (meth) acrylate), 2-hydroxypropyl (meth) acrylate, (meth) acrylic acid 4 -Hydroxybutyl, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) ) Hydroxyl group-containing monomer such as methyl acrylate

Furthermore, in addition to the above monomers, the following polyfunctional monomers can be used. For example, hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, tri Examples include methylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. These polyfunctional monomers can also be used alone or in combination of two or more.

The acrylic polymer preferably has a hydroxyl group and a carboxyl group. The hydroxyl value of the acrylic polymer is preferably 1-30, more preferably 1-10. Here, the hydroxyl value refers to a value measured by a method based on JIS K 0070. Further, the acid value of the acrylic polymer is preferably 1 to 20, and more preferably 1 to 15. Here, the acid value means a value measured by the method described in JIS K 5407.
The hydroxyl group reacts with an isocyanate cross-linking agent or an isocyanurate cross-linking agent used as a cross-linking agent described later to cross-link the intermediate resin layer. Moreover, a carboxyl group reacts with the epoxy crosslinking agent used as a below-mentioned crosslinking agent, and bridge | crosslinks an intermediate resin layer.

The acrylic polymer can be obtained by subjecting one or more monomer mixtures to polymerization. The polymerization can be performed by any method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization and the like. The weight average molecular weight of the acrylic polymer is preferably 50,000 or more, more preferably about 100,000 to 1,000,000. Here, the weight average molecular weight of the acrylic polymer can be measured by the method described later. Other resins can be blended in the intermediate resin layer composition as long as it is compatible with the acrylic polymer.

Cohesive force can be added to the intermediate resin layer by crosslinking the acrylic polymer. By adding a cohesive force to the intermediate resin layer, even if the semiconductor wafer is warped after the thickness of the semiconductor wafer is ground to 100 μm or less, the intermediate resin layer is formed between the base resin film layer and the adhesive layer. By being directly present between them, warpage of the semiconductor wafer can be suppressed. In particular, this effect can be achieved even when a polyimide film is formed on the surface of the semiconductor wafer. For this reason, a crosslinking agent is mix | blended with an intermediate | middle resin layer composition. Examples of the crosslinking agent include, as described above, an isocyanate crosslinking agent, an isocyanurate crosslinking agent, an epoxy crosslinking agent, a metal chelate crosslinking agent, an aziridine crosslinking agent, and an amine resin corresponding to the base resin component. Furthermore, the intermediate resin layer composition may contain various additive components as desired within a range not impairing the object of the present invention.

As the intermediate resin layer composition, polyurethane acrylate can be used in addition to the acrylic polymer. Examples of the polyurethane acrylate include those having the following urethane (meth) acrylate monomers as constituent components. For example, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, phenylhydroxypropyl acrylate, and the like can be given. These can use 1 type (s) or 2 or more types. When forming the intermediate layer, the urethane acrylate oligomer can be diluted with a photopolymerizable monomer, coated and dried, and effected by ultraviolet irradiation or the like, and this method is preferred as a method for forming the intermediate layer.
The polyurethane acrylate preferably has a hydroxyl group and a carboxyl group. The hydroxyl value of the polyurethane acrylate is preferably 1 to 30, more preferably 1 to 10. Here, the hydroxyl value means a value measured according to the following JIS K 0070. The acid value of the polyurethane acrylate is preferably 1-20, and more preferably 1-15. Here, the acid value is a value measured by the method described in JIS K 5601-2-1.

(Measuring method of hydroxyl value (JIS K 0070))
(1) Reagents used • Acetylation reagent (acetic anhydride-pyridine)
N / 2 potassium hydroxide-ethanol solution (2) Titration method After acetylating a sample with an acetylating reagent, excess acetic acid is titrated with an N / 2 potassium hydroxide-ethanol solution.
(3) Calculation formula The hydroxyl value is determined by the following formula.
Hydroxyl value = ((VB−V) × F × 28.5) / S
However,
V: titration of N / 2 potassium hydroxide-ethanol solution in this test (mL)
VB: Titrate of N / 2 potassium hydroxide-ethanol solution for blank test (mL)
F: Factor of N / 2 potassium hydroxide-ethanol solution S: Sampling amount (g)
AV: Acid value of the sample (mgKOH / g)

The hydroxyl group reacts with an isocyanate-based cross-linking agent or an isocyanurate-based cross-linking agent used as a cross-linking agent, which will be described later, to cross-link the intermediate resin layer. Moreover, a carboxyl group reacts with the epoxy type crosslinking agent used as a below-mentioned crosslinking agent, and bridge | crosslinks an intermediate resin layer. When polyurethane acrylate is used as the intermediate resin layer, a cohesive force can be applied to the intermediate resin layer as in the case of the acrylic polymer, and the surface of the semiconductor wafer ground to a thickness of 100 μm or less. This effect can be achieved even when a polyimide film is formed.

The intermediate resin layer of the adhesive tape for protecting a semiconductor wafer surface of the present invention can provide cushioning properties to the base resin film, and can relieve the tension applied when the adhesive tape is bonded. The intermediate resin layer preferably has a higher elastic modulus than the pressure-sensitive adhesive layer.
In order to give rigidity at normal temperature, the preferable range of the glass transition point (Tg) by DSC of the intermediate resin layer after crosslinking is −10 ° C. to 30 ° C., more preferably 0 ° C. to 20 ° C. If the glass transition temperature after crosslinking of the intermediate layer is too low, the semiconductor wafer surface protecting adhesive tape has flexibility, so that the cushioning property is improved, but the thin film grindability may be lowered. In the final finishing process of a thin film wafer such as dry polish, a high pressure is applied to the semiconductor wafer. If the thin film grindability is low, the semiconductor wafer may be cracked due to the sinking effect of the surface protecting adhesive tape at the high pressure. In particular, when grinding a semiconductor wafer to a thickness of 50 μm or less, dry polishing, chemical mechanical polishing, polygrinding, etc. are performed to finish the back surface in a mirror state in order to increase the strength of the semiconductor wafer. There may be many cracks due to the sinking of the protective adhesive tape.
On the other hand, if the glass transition temperature after cross-linking of the intermediate resin layer is too high, the cushioning property is lowered, and when the patterned wafer is processed, the semiconductor wafer may be cracked. Moreover, the material which hardens | cures by radiation irradiation may be used for the intermediate resin layer composition, and you may make it harden | cure by radiation irradiation and may adjust the hardness of an intermediate resin layer.
The thickness of the intermediate resin layer is preferably 10 to 100 μm, more preferably 20 to 80 μm, and more preferably 30 to 70 μm, from the viewpoint of cushioning in the back grinding process. If the intermediate resin layer is too thin, the cushioning property during the back surface grinding process is reduced, and if the intermediate resin layer is too thick, the probability that the wafer is broken from the center due to the sinking effect during thin film grinding is increased. This phenomenon is particularly noticeable in the polishing process used in thin film grinding, which is considered to be because the pressure on the wafer is higher than in the grinding process. The intermediate resin layer may have a configuration in which a plurality of layers are laminated.

The base resin film refers to the layer having the highest elastic modulus among the materials (types) constituting the semiconductor wafer surface protecting adhesive tape of the present invention. The base resin film can protect the semiconductor wafer from warping and can prevent warping of the semiconductor wafer while protecting the semiconductor wafer from the back surface grinding and back surface polishing. In particular, the base resin film needs to have water resistance against water washing or the like at the time of back surface grinding or back surface polishing of the semiconductor wafer, and to have flexibility enough to hold the semiconductor wafer. More importantly, the correction force can be applied to the warp stress of the semiconductor wafer caused by the residual stress in the insulating film such as polyimide on the semiconductor wafer. The base resin film is not particularly limited as long as it satisfies these characteristics. In particular, from the point that the warp of the semiconductor wafer after thin film grinding can be corrected, a resin composition containing a polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polybutylene terephthalate (PBT) Polyimide is preferred. More preferably, it is PET or PEN. It is preferable to use a polyester-based resin for the outermost layer on the side opposite to the pressure-sensitive adhesive layer because heat resistance can be imparted simultaneously. In this case, when the semiconductor wafer surface protecting adhesive tape of the present invention is stuck to the semiconductor wafer surface and adsorbed to the semiconductor wafer holding member (for example, a chuck table) with the base resin film surface of the tape, Even if heating is performed when the dicing die-bonding tape is bonded to the back surface of the semiconductor wafer, it is possible to reduce the adhesion of the surface-protecting adhesive tape to the chuck table. For this reason, wafer cracking can be reduced.

Moreover, the resin composition which mix | blended the resin which has a softness | flexibility rather than a polyester-type resin with a polyester-type resin can be used as a base resin film. By setting it as the resin composition which blended 2 or more types of resin, it can be set as the base material which gave rigidity and a softness | flexibility. For example, a resin composition in which a thermoplastic elastomer is blended with a polyester-based resin can be used as the base resin film.
In that case, a semiconductor wafer with an 8-inch polyimide film to which the adhesive tape for protecting the surface of the semiconductor wafer of the present invention is bonded has a warp correction rate of 75% or less and an 8-inch semiconductor with a polyimide film formed on the surface. The surface warp adhesive tape is bonded to the wafer surface and the back surface of the semiconductor wafer is ground to a thickness of 50 μm. The amount of forward warping of the 8-inch wafer to which the adhesive tape is bonded is 20 mm or less. preferable.

When the radiation curable resin composition is used as the adhesive layer described later, the base resin film is preferably a radiation transmissive one. The thickness of the base resin film is not particularly limited, but is preferably 10 to 500 μm, more preferably 40 to 500 μm, and particularly preferably 80 to 250 μm. When the base film 3 is a polyester resin, the thickness of the base resin film is preferably 12 to 80 μm.

As the base resin constituting the pressure-sensitive adhesive layer, a conventional resin can be used. Among them, an acrylic pressure-sensitive adhesive is preferable, specifically, an acrylic polymer selected from a homopolymer and a copolymer having an acrylate ester as a main constituent monomer unit, and other functional monomers. Copolymers and mixtures of these polymers are used. For example, as the acrylic ester, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, etc., and those obtained by replacing the above acrylic ester with, for example, methacrylic ester, etc. Can also be preferably used.
Furthermore, monomers such as acrylic acid, methacrylic acid, acrylonitrile, and vinyl acetate may be copolymerized for the purpose of controlling adhesiveness and cohesive force.

The pressure-sensitive adhesive as described above can further set the pressure-sensitive adhesive force and cohesive force to arbitrary values by using a crosslinking agent. Examples of such a crosslinking agent include a polyvalent isocyanate compound, a polyvalent epoxy compound, a polyvalent aziridine compound, and a chelate compound. Specific examples of the polyvalent isocyanate compound include toluylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and adduct type compounds thereof.
Specific examples of the polyvalent epoxy compound include ethylene glycol diglycidyl ether, terephthalic acid diglycidyl ester acrylate, and the like. Specific examples of the polyvalent aziridine compound include tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, tris [1- (2-methyl) -aziridinyl] phosphine oxide, hexa [ 1- (2-Methyl) -aziridinyl] triphosphatriazine and the like are used. As the chelate compound, specifically, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) or the like is used.

As the pressure-sensitive adhesive layer used for the semiconductor wafer surface protecting pressure-sensitive adhesive tape of the present invention, any of a radiation-curable pressure-sensitive adhesive that is peeled off by reducing the adhesive strength by radiation irradiation and a pressure-sensitive adhesive that is not cured by radiation are used as appropriate. can do. In this specification, an adhesive that is not cured by radiation is referred to as a pressure-sensitive adhesive tape. When the pressure-sensitive adhesive is pressure sensitive, the adhesive strength to the SUS polished surface at 20 to 25 ° C. is 0.5 N / 25 mm or more, and the adhesive strength to the SUS polished surface at 50 ° C. is 0.5 N / 25 mm or less. It is preferable. If the adhesive strength to the SUS polished surface at 20 to 25 ° C. is too low, the holding force is not sufficient, and the wafer may be displaced or cracked during backside grinding of the wafer. Preferably, the adhesive strength to the SUS polished surface at 20 to 25 ° C. is 1.0 N / 25 mm or more.
Usually, the pressure-sensitive adhesive tape is peeled off by heating. If the adhesive force to the SUS polished surface by heat peeling at 50 ° C. is too large, the peeling after thin film grinding may be hindered and the wafer may be cracked. The pressure-sensitive adhesive tape of the present invention preferably has an adhesive strength to a SUS280 polished surface at 50 ° C. of 0.3 N / 25 mm or less.
In the present invention, the “SUS polished surface” is a SUS304 steel plate defined in JIS G 4305, finished using JIS R 6253, No. 280 abrasive paper, based on JIS Z 0237. Say something.

When the pressure-sensitive adhesive is pressure-sensitive, the weight average molecular weight of the base resin is preferably 1,000,000 or more. If the molecular weight is too small, organic contaminants tend to adhere to the wafer surface, which is not preferable. Although there is no restriction | limiting in particular about the upper limit of molecular weight, In consideration of the ease of superposition | polymerization etc., it is preferable that a weight average molecular weight is 2.5 million or less.
The weight average molecular weight can be measured by GPC (gel permeation chromatograph) under the following conditions.
GPC device: HLC-8120GPC (trade name, manufactured by Tosoh Corporation)
Column: TSK gel SuperHM-H / H4000 / H3000 / H2000 (trade name, manufactured by Tosoh Corporation)
Flow rate: 0.6 mL / min,
Concentration: 0.3% by mass
Injection volume: 20 μL,
Column temperature: 40 ° C

In the present invention, a radiation-curable pressure-sensitive adhesive can be used as the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer. Among them, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is a polymer containing an acrylic monomer having a radiation-polymerizable carbon-carbon double bond-containing group with respect to the main chain as a constituent unit (hereinafter referred to as polymer (a It is preferable to use a base resin whose main component is. In this specification, this polymer (a) is also called a reactive polymer. The polymer (a) may be produced by any method. For example, a copolymer (a1) comprising (meth) acrylic acid ester, hydroxyl group-containing unsaturated compound, carboxyl group-containing unsaturated compound, and the like. Obtained by subjecting a compound (a2) having a carbon-carbon double bond and a functional group capable of undergoing an addition reaction to the functional group of the copolymer (a1). Things.

Examples of the (meth) acrylic acid ester include hexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, decyl acrylate, or a monomer having 5 or less carbon atoms. Specific examples include pentyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl acrylate, methyl acrylate, and methacrylates similar to these. In this case, as the monomer having a larger carbon number is used as the monomer, the glass transition point becomes lower, so that the desired glass transition point can be produced. In addition to the glass transition point, a low molecular compound having a carbon-carbon double bond such as vinyl acetate, styrene or acrylonitrile can be added within the range of 5% by mass or less for the purpose of improving compatibility and various performances. .

Examples of hydroxyl group-containing unsaturated compounds include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and the like. Examples of the carboxyl group-containing unsaturated compound include acrylic acid and methacrylic acid.

As the functional group of the compound (a2) having a functional group capable of undergoing addition reaction and a carbon-carbon double bond, the functional group of the copolymer (a1) is a carboxyl group or a cyclic acid anhydride group. In the case, a hydroxyl group, an epoxy group, an isocyanate group, etc. can be mentioned. When the functional group of (a2) is a hydroxyl group, a cyclic acid anhydride group, an isocyanate group, etc. can be mentioned. When the functional group of (a2) is an amino group, an isocyanate group can be exemplified. Specific examples of the compound (a2) include acrylic acid, methacrylic acid, cinnamic acid, itaconic acid, fumaric acid, phthalic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, glycol monoacrylates, glycol monoacrylate. Methacrylates, N-methylolacrylamide, N-methylolmethacrylamide, allyl alcohol, N-alkylaminoethyl acrylates, N-alkylaminoethyl methacrylates, acrylamides, methacrylamides, maleic anhydride, itaconic anhydride, fumaric anhydride Acid, phthalic anhydride, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, a part of isocyanate groups of polyisocyanate compounds are hydroxyl groups or carboxyl groups and photopolymerizable carbon It is possible to enumerate such as those urethanization a monomer having a carbon-carbon double bond.

In the synthesis of the acrylic copolymer (a), as the organic solvent when the copolymerization is performed by solution polymerization, a ketone, ester, alcohol, or aromatic solvent can be used. Among them, generally good solvents for acrylic polymers, such as toluene, ethyl acetate, isopropyl alcohol, benzene methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, and solvents having a boiling point of 60 to 120 ° C. are preferred, and polymerization initiators include α, α Radical generators such as azobis compounds such as' -azobisisobutylnitrile and organic peroxide compounds such as benzoberperoxide are usually used. At this time, if necessary, a catalyst and a polymerization inhibitor can be used in combination, the polymerization temperature and the polymerization time are adjusted, and then an addition reaction at a functional group is performed, whereby an acrylic copolymer (a ) Can be obtained. In terms of adjusting the molecular weight, it is preferable to use a mercaptan or carbon tetrachloride solvent. The copolymerization is not limited to solution polymerization, and other methods such as bulk polymerization and suspension polymerization may be used.

Further, by containing a photopolymerizable compound in the pressure-sensitive adhesive, the pressure-sensitive adhesive force can be further reduced by irradiating the pressure-sensitive adhesive layer with radiation, particularly preferably ultraviolet rays. Examples of such a photopolymerizable compound include photopolymerizable carbon in a molecule that can be three-dimensionally reticulated by light irradiation as disclosed in, for example, JP-A-60-196956 and JP-A-60-223139. -Low molecular weight compounds having at least two carbon double bonds are widely used. Specifically, for example, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6-hexane Diol diacrylate, polyethylene glycol diacrylate, commercially available oligoester acrylate, and the like are used.

Further, by blending a photoinitiator in the pressure-sensitive adhesive, it is possible to reduce the polymerization curing time and light irradiation amount by light irradiation. Specific examples of such photoinitiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyldiphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β -Chloranthraquinone and the like. The photoinitiator is usually used in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the photopolymerizable compound. By irradiating the photocrosslinkable pressure-sensitive adhesive layer thus formed with light, preferably ultraviolet rays, the initial adhesive strength is greatly reduced, and the pressure-sensitive adhesive tape can be easily peeled off from the adherend. it can.

A release liner (not shown) can be provided on the adhesive layer 2 of the adhesive tape 20 for protecting a semiconductor wafer surface of the present invention shown in FIG.
As the release liner, a polyethylene terephthalate film subjected to silicon release treatment or the like is used. If necessary, polypropylene or the like that is not subjected to silicon release treatment is also used.

The adhesive tape for surface protection of a semiconductor wafer of the present invention has a warp correction rate C represented by the following formula (1) of 75% or less in a semiconductor wafer with an 8-inch polyimide film to which the tape is bonded. Can do. More preferably, the warp correction rate C can be 50% or less.
C = (A / B) × 100 Formula (1)
In formula (1), A, B, and C represent the following.
A: A polyimide film having a thickness of 6 μm is formed on the surface, and the entire thickness of the wafer is 725 μm. A surface protective adhesive tape is bonded to the polyimide film surface of an 8-inch silicon semiconductor wafer, and the back surface of the semiconductor wafer is The amount of forward warping (mm) of the 8-inch wafer to which the adhesive tape was ground after being ground to a thickness of 50 μm
B: A polyimide film having a thickness of 6 μm is formed on the surface, the thickness of the whole wafer is 725 μm, and an adhesive tape for surface protection is bonded to the surface of the polyimide film of an 8-inch diameter silicon semiconductor wafer, The amount of forward warping (mm) of the 8-inch wafer after grinding to 50 μm thickness and peeling of the adhesive tape
C: Warpage correction rate (%)
In the above formula (1), the polyimide film is non-photosensitive polyimide PIX-3400 (trade name, manufactured by Hitachi Chemical DuPont Microsystems Co., Ltd.), and the film thickness after drying is 6 μm while edge rinsing with a spin coater. Then, a silicon semiconductor wafer having a diameter of 8 inches is applied, and then prebaked at 200 ° C. for 30 minutes, followed by baking at 350 ° C. for 1 hour to form a polyimide film having a thickness of 6 μm. Say.

Even if the semiconductor wafer surface protective adhesive tape of the present invention is ground to a thin film of a semiconductor wafer with an insulation film such as polyimide, the stress relaxation effect of the intermediate resin layer reduces the tension applied at the time of tape bonding. Along with the effect and the warp correction effect of the base resin film layer, the layer including the base resin film layer, the intermediate resin layer and the pressure-sensitive adhesive layer is subjected to stress during grinding evenly in the vertical and horizontal directions. Without setting a proper bonding condition, the warp correction rate exceeding the residual stress of the polyimide insulating film can be exhibited, and the warpage of the semiconductor wafer after grinding can be reduced.
In addition, an insulating film such as polyimide formed on the surface of a semiconductor wafer is often crosslinked by heating or the like. For this reason, residual stress may exist in the insulating film. Even in this case, even if the semiconductor wafer surface protective adhesive tape of the present invention is bonded to the wafer surface and ground, the warp correction rate exceeding the residual stress of the insulating film is exhibited and the warp of the semiconductor wafer after grinding is reduced. be able to.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.
<Example 1>
For 100 parts by mass of an acrylic copolymer having a weight average molecular weight of 800,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxyl group-containing group, the adduct isocyanate crosslinker Coronate L ( 1 part by mass of product name (manufactured by Nippon Polyurethane Co., Ltd.) and 3 parts by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan) were mixed, and the concentration was adjusted with ethyl acetate to obtain an adhesive composition.
In addition, 100 parts by mass of an acrylic copolymer (having an acid value of 10 and a hydroxyl value of 2) having n-butyl methacrylate as a main component and having a hydroxyl group and a carboxyl group as monomers of other components 2 parts by mass of adduct isocyanate crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane) and 2 parts by mass of epoxy crosslinking agent TETRAD-C (trade name, manufactured by Mitsubishi Gas Chemical) are mixed with ethyl acetate. Were adjusted to obtain an intermediate resin layer composition.
The intermediate resin layer composition was applied on one side of a 38 μm thick polyethylene terephthalate base resin film (PET) and then dried to laminate an intermediate resin layer having a dry film thickness of 42 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was 0 ° C. This glass transition temperature is a value measured by a differential scanning calorimeter (DSC).
Furthermore, said adhesive composition was apply | coated on 25-micrometer-thick PET separator, and was dried. Then, this adhesive composition layer and the intermediate resin layer formed on said base resin film were faced | matched, and the adhesive tape for semiconductor wafer surface protection which has an adhesive layer with a dry film thickness of 20 micrometers was produced.
The weight average molecular weight of the acrylic copolymer was measured by GPC (gel permeation chromatography) under the following conditions.
GPC device: HLC-8120GPC (trade name, manufactured by Tosoh Corporation)
Column: TSK gel SuperHM-H / H4000 / H3000 / H2000 (trade name, manufactured by Tosoh Corporation)
Flow rate: 0.6 mL / min,
Concentration: 0.3% by mass
Injection volume: 20 μL,
Column temperature: 40 ° C
For the acrylic copolymers used in Examples 2 to 11 and Comparative Examples 1 to 6 below, the weight average molecular weight was measured in the same manner, and the results are shown in Tables 1 to 3. Also in Examples 2 to 11 and Comparative Examples 1 to 6 below, the glass transition temperature of the intermediate resin layer was measured by DSC as in Example 1.

<Example 2>
For 100 parts by mass of an acrylic copolymer having a weight-average molecular weight of 800,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxyl group-containing group, adduct isocyanate crosslinking agent Coronate L (product Name, manufactured by Nippon Polyurethane Co., Ltd.) and 1 part by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan Co., Ltd.) were mixed, and the concentration was adjusted with ethyl acetate to obtain an adhesive composition.
In addition, 100 parts by mass of an acrylic copolymer (having an acid value of 11 and a hydroxyl value of 3) containing n-butyl methacrylate as a main component and having a hydroxyl group and a carboxyl group as monomers of other components 1 part by weight of adduct isocyanate crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane) and 2 parts by weight of epoxy crosslinking agent TETRAD-C (trade name, manufactured by Mitsubishi Gas Chemical Company) Were adjusted to obtain an intermediate resin layer composition.
The intermediate resin layer composition was applied on one side of a 38 μm thick polyethylene terephthalate base film (PET) and then dried to laminate an intermediate resin layer having a dry film thickness of 42 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was −15 ° C.
Furthermore, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 20 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Example 3>
For 100 parts by mass of an acrylic copolymer having a weight-average molecular weight of 800,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxyl group-containing group, adduct isocyanate crosslinking agent Coronate L (product Name, manufactured by Nippon Polyurethane Co., Ltd.) and 1 part by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan Co., Ltd.) were mixed, and the concentration was adjusted with ethyl acetate to obtain an adhesive composition.
In addition, polyisocyanate cross-linking agent TKA-100 (trade name, manufactured by Asahi Kasei Chemicals Corporation) with respect to 100 parts by mass of an acrylic copolymer having a hydroxyl group (hydroxyl value 35) having n-butyl methacrylate as one of the constituent components. 12 parts by mass, and the concentration was adjusted with ethyl acetate to obtain an intermediate resin layer composition.
The intermediate resin layer composition was applied onto one side of a 25 μm thick polyethylene naphthalate base film (PEN) and then dried to laminate an intermediate resin layer having a dry film thickness of 50 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was 30 ° C.
Further, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 30 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Example 4>
4 parts by mass of an isocyanate-based crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is blended with 100 parts by mass of an acrylic copolymer having a weight average molecular weight of 1,000,000, and the concentration is adjusted with ethyl acetate. Produced.
In addition, 100 parts by mass of an acrylic copolymer (having an acid value of 11 and a hydroxyl value of 4) having n-butyl methacrylate as a main component and having a hydroxyl group and a carboxyl group, the adduct isocyanate cross-linking agent Coronate L 1 part by mass (trade name, manufactured by Nippon Polyurethane Co., Ltd.) and 1 part by weight of epoxy-based cross-linking agent TETRAD-C (trade name, manufactured by Mitsubishi Gas Chemical Co., Ltd.), the concentration is adjusted with ethyl acetate, and the intermediate resin layer composition Got.
The intermediate resin layer composition was applied on one side of a 38 μm thick polyethylene terephthalate base film (PET) and then dried to laminate an intermediate resin layer having a dry film thickness of 62 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was −10 ° C.
Further, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 30 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Example 5>
2 parts by mass of isocyanate-based crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane) and 100% by mass of acrylic copolymer having a weight average molecular weight of 1,200,000 and epoxy-based crosslinking agent TETRAD-C (trade name, Mitsubishi Gas Chemical) 4 parts by mass) was prepared, and the pressure-sensitive adhesive composition was prepared by adjusting the concentration with ethyl acetate.
Furthermore, adduct isocyanate coronate L (100 parts by mass of an acrylic copolymer having a main component of n-butyl methacrylate and having a hydroxyl group and a carboxyl group (acid value 11 and hydroxyl value 3) ( 2 parts by mass of a trade name (manufactured by Nippon Polyurethane Co., Ltd.) and 2 parts by mass of an epoxy-based cross-linking agent TETRAD-C (trade name, manufactured by Mitsubishi Gas Chemical Company), and adjusting the concentration with ethyl acetate, an intermediate resin layer composition Got.
The intermediate resin layer composition was applied on one side of a 38 μm thick polyethylene terephthalate base film (PET) and then dried to laminate an intermediate resin layer having a dry film thickness of 42 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was 0 ° C.
Furthermore, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 20 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Example 6>
0.5 parts by mass of an isocyanate-based crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is blended with 100 parts by mass of an acrylic copolymer having a weight average molecular weight of 800,000, and the concentration is adjusted with ethyl acetate. A product was made.
Furthermore, adduct isocyanate coronate L (100 parts by mass of an acrylic copolymer having a main component of n-butyl methacrylate and having a hydroxyl group and a carboxyl group (acid value: 12, hydroxyl value: 5) ( 2 parts by mass of a trade name (manufactured by Nippon Polyurethane Co., Ltd.) and 4 parts by mass of an epoxy-based cross-linking agent TETRAD-C (trade name, produced by Mitsubishi Gas Chemical Co., Ltd.), adjusting the concentration with ethyl acetate, and intermediate resin layer composition Got.
The intermediate resin layer composition was applied on one side of a 50 μm thick polyethylene terephthalate base film (PET) and then dried to laminate an intermediate resin layer having a dry film thickness of 50 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was 15 ° C.
Further, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 30 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Example 7>
4 parts by mass of isocyanate cross-linking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) per 100 parts by mass of an acrylic base resin having a molecular weight of 700,000 which is a copolymer of 2-ethylhexyl acrylate, methyl acrylate and 2-hydroxyethyl acrylate 1 part by mass of 100 parts of tetramethylolmethane tetraacrylate having a photopolymerizable carbon-carbon double bond as an oligomer and 1 part by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan), and the concentration is adjusted with ethyl acetate. It adjusted and produced the adhesive composition.
In addition, adduct isocyanate coronate L (100 parts by mass of an acrylic copolymer having n-butyl methacrylate as a main component and having a hydroxyl group and a carboxyl group (acid value 11 and hydroxyl value 2) ( 2 parts by mass of a trade name (manufactured by Nippon Polyurethane Co., Ltd.) and 2 parts by mass of an epoxy-based cross-linking agent TETRAD-C (trade name, manufactured by Mitsubishi Gas Chemical Company), and adjusting the concentration with ethyl acetate, an intermediate resin layer composition Got.
The intermediate resin layer composition was applied on one side of a 38 μm thick polyethylene terephthalate base film (PET) and then dried to laminate an intermediate resin layer having a dry film thickness of 42 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was 0 ° C.
Furthermore, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 20 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Example 8>
1.5 parts by mass of the isocyanate-based cross-linking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is blended with 100 parts by mass of the acrylic copolymer having a weight average molecular weight of 800,000, and the concentration is adjusted with ethyl acetate. A product was made.
In addition, 3 parts by mass of an epoxy crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) and 100 parts by mass of an epoxy crosslinking agent with respect to 100 parts by mass of a polyurethane acrylate having a hydroxyl group and a carboxyl group (acid value: 2, hydroxyl value: 35) 4 parts by mass of the agent TETRAD-C (trade name, manufactured by Mitsubishi Gas Chemical Company) was blended, and the concentration was adjusted with ethyl acetate to obtain an intermediate resin layer composition.
The intermediate resin layer composition was applied onto one side of a 25 μm thick polyethylene naphthalate base film (PEN) and then dried to laminate an intermediate resin layer having a dry film thickness of 50 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was 30 ° C.
Further, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 30 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Example 9>
For 100 parts by mass of an acrylic copolymer having a weight-average molecular weight of 800,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxyl group-containing group, adduct isocyanate crosslinking agent Coronate L (product Name, manufactured by Nippon Polyurethane Co., Ltd.) and 1 part by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan Co., Ltd.) were mixed, and the concentration was adjusted with ethyl acetate to obtain an adhesive composition.
Further, an adduct isocyanate coronate L (100 parts by mass of an acrylic copolymer having a hydroxyl group and a carboxyl group (acid value is 10 and hydroxyl value is 2) having n-butyl methacrylate as one of the constituent components. 2 parts by mass of a trade name (manufactured by Nippon Polyurethane Co., Ltd.) and 2 parts by mass of an epoxy-based cross-linking agent TETRAD-C (trade name, manufactured by Mitsubishi Gas Chemical Company), and adjusting the concentration with ethyl acetate, an intermediate resin layer composition Got.
The intermediate resin layer composition was applied on one side of a 75 μm thick polyethylene terephthalate base film (PET) and then dried to laminate an intermediate resin layer having a dry film thickness of 25 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was 0 ° C.
Further, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 30 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Example 10>
For 100 parts by mass of an acrylic copolymer having a weight-average molecular weight of 800,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxyl group-containing group, adduct isocyanate crosslinking agent Coronate L (product Name, manufactured by Nippon Polyurethane Co., Ltd.) and 1 part by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan Co., Ltd.) were mixed, and the concentration was adjusted with ethyl acetate to obtain an adhesive composition.
Further, an adduct isocyanate coronate L (100 parts by mass of an acrylic copolymer having a hydroxyl group and a carboxyl group (acid value is 10 and hydroxyl value is 2) having n-butyl methacrylate as one of the constituent components. 2 parts by mass of a trade name (manufactured by Nippon Polyurethane Co., Ltd.) and 2 parts by mass of an epoxy-based cross-linking agent TETRAD-C (trade name, manufactured by Mitsubishi Gas Chemical Company), and adjusting the concentration with ethyl acetate, an intermediate resin layer composition Got.
The intermediate resin layer composition was applied on one side of a polyimide base film having a thickness of 40 μm and then dried to laminate an intermediate resin layer having a dry film thickness of 30 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was −5 ° C.
Further, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 30 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Example 11>
For 100 parts by mass of an acrylic copolymer having a weight average molecular weight of 800,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxyl group-containing group, the adduct isocyanate crosslinker Coronate L ( 1 part by mass of product name (manufactured by Nippon Polyurethane Co., Ltd.) and 3 parts by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan) were mixed, and the concentration was adjusted with ethyl acetate to obtain an adhesive composition.
An isocyanate-based cross-linking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is 0.5 per 100 parts by mass of an acrylic copolymer having a hydroxyl group with a weight average molecular weight of 400,000 (acid value is 4, hydroxyl value is 33). An intermediate resin layer composition was prepared by blending parts by mass and adjusting the concentration with ethyl acetate.
The intermediate resin layer composition was applied on one side of a 38 μm thick polyethylene terephthalate substrate film (PET), dried, and then laminated several times to laminate an intermediate resin layer having a dry film thickness of 132 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was −50 ° C.
A pressure-sensitive adhesive composition is applied on a PET separator having a thickness of 50 μm, dried and laminated on one side of a multilayer film of PET and EVA, and a pressure-sensitive adhesive layer having a thickness of 10 μm is laminated. An adhesive tape for protecting the surface of a semiconductor wafer was produced.

<Comparative Example 1>
For 100 parts by mass of an acrylic copolymer having a weight average molecular weight of 800,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxyl group-containing group, the adduct isocyanate crosslinker Coronate L ( 1 part by mass of product name (manufactured by Nippon Polyurethane Co., Ltd.) and 3 parts by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan) were mixed, and the concentration was adjusted with ethyl acetate to obtain an adhesive composition.
In addition, adduct isocyanate coronate L (for 100 parts by mass of an acrylic copolymer (having an acid value of 11 and a hydroxyl value of 2) having n-butyl methacrylate as one of the components and having a hydroxyl group and a carboxyl group ( 2 parts by mass of a trade name (manufactured by Nippon Polyurethane Co., Ltd.) and 2 parts by mass of an epoxy-based cross-linking agent TETRAD-C (trade name, manufactured by Mitsubishi Gas Chemical Company), and adjusting the concentration with ethyl acetate, an intermediate resin layer composition Got.
The intermediate resin layer composition was applied on one side of a 40 μm thick polypropylene (PP) substrate film and then dried to laminate an intermediate resin layer having a dry film thickness of 40 μm. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was 0 ° C.
Furthermore, a pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on a tape provided with an intermediate resin layer, and a pressure-sensitive adhesive layer with a thickness of 20 μm is laminated to form a semiconductor. An adhesive tape for protecting the wafer surface was produced.

<Comparative Example 2>
1.0 part by mass of an isocyanate-based crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) and 100 parts by weight of an acrylic copolymer having a weight average molecular weight of 400,000, and an epoxy-based crosslinking agent TETRAD-C (trade name, Mitsubishi 2.5 parts by mass of Gas Chemical Co., Ltd.) was blended, and the concentration was adjusted with ethyl acetate to prepare an adhesive composition.
A pressure-sensitive adhesive composition is applied onto a 25 μm-thick PET separator, dried and laminated on one side of a 165 μm-thick ethylene vinyl acetate copolymer (EVA) film, and the pressure-sensitive adhesive has a thickness of 40 μm. The adhesive layer for semiconductor wafer surface protection was produced by laminating the agent layer.

<Comparative Example 3>
Isocyanate-based crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is added to 100 parts by mass of an acrylic base resin having a molecular weight of 700,000 which is a copolymer of 2-ethylhexyl acrylate, methyl acrylate and 2-hydroxyethyl acrylate. 1 part by mass of 100 parts by mass of tetramethylol methane tetraacrylate having a photopolymerizable carbon-carbon double bond as an oligomer and 1 part by mass of a photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan Co., Ltd.) is added and concentrated with ethyl acetate. The pressure-sensitive adhesive composition was prepared.
On one side of a polyethylene terephthalate base film (PET) having a thickness of 100 μm, the pressure-sensitive adhesive composition was applied and then dried, and a pressure-sensitive adhesive layer having a dried thickness of 15 μm was laminated. Further, a PET separator was laminated on this pressure-sensitive adhesive layer to produce a semiconductor wafer surface protective pressure-sensitive adhesive tape.

<Comparative Example 4>
4 parts by mass of isocyanate cross-linking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) per 100 parts by mass of an acrylic base resin having a molecular weight of 700,000 which is a copolymer of 2-ethylhexyl acrylate, methyl acrylate and 2-hydroxyethyl acrylate , 100 parts of tetramethylolmethane tetraacrylate having a photopolymerizable carbon-carbon double bond as an oligomer and 1 part by weight of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan Co., Ltd.), and the concentration is adjusted with ethyl acetate A pressure-sensitive adhesive composition was prepared.
A pressure-sensitive adhesive composition was applied onto a PET separator having a thickness of 25 μm, dried, and a multilayer film substrate of a high-density polyethylene (HDPE) having a thickness of 30 μm and an ethylene-vinyl acetate copolymer having a thickness of 70 μm was formed. An adhesive tape for protecting the surface of a semiconductor wafer was prepared by laminating by sticking on an ethylene-vinyl acetate copolymer layer and laminating an adhesive layer having a thickness of 30 μm.

<Comparative Example 5>
For 100 parts by mass of an acrylic copolymer having a weight average molecular weight of 800,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxyl group-containing group, the adduct isocyanate crosslinker Coronate L ( 1 part by mass of product name (manufactured by Nippon Polyurethane Co., Ltd.) and 3 parts by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan) were mixed, and the concentration was adjusted with ethyl acetate to obtain an adhesive composition.
With respect to 100 parts by mass of an acrylic copolymer having a weight-average molecular weight of 200,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a group containing a carboxyl group (acid value is 4, hydroxyl value is 33) 0.5 parts by mass of adduct isocyanate crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) and 5 parts by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan Co., Ltd.) The pressure-sensitive adhesive composition was obtained by adjusting the concentration.
A pressure-sensitive adhesive composition was applied onto a PET separator having a thickness of 50 μm, dried, and a multilayer film substrate of high-density polyethylene (HDPE) having a thickness of 20 μm and an ethylene-vinyl acetate copolymer having a thickness of 180 μm was formed. Lamination was performed by laminating several times on the ethylene-vinyl acetate copolymer layer, and an intermediate resin layer having a thickness of 130 μm was laminated. At this time, the glass transition temperature after crosslinking of the intermediate resin layer was −50 ° C.
Apply a pressure-sensitive adhesive composition on a 50 μm thick PET separator, dry it, and laminate it by laminating it on a film laminated with an intermediate resin layer. Laminate a 5 μm thick pressure-sensitive adhesive layer on the surface of the semiconductor wafer A protective adhesive tape was prepared.

<Comparative Example 6>
For 100 parts by mass of an acrylic copolymer having a weight average molecular weight of 800,000 each having a radiation-curable carbon-carbon double bond-containing group, a hydroxyl group, and a carboxyl group-containing group, an adduct isocyanate crosslinker Coronate L 1 part by mass (trade name, manufactured by Nippon Polyurethane Co., Ltd.) and 3 parts by mass of photopolymerization initiator Irgacure 184 (trade name, manufactured by Ciba Japan Co., Ltd.) were mixed, and the concentration was adjusted with ethyl acetate to obtain an adhesive composition. .
An EVA resin layer having a thickness of 50 μm was formed by extruding an ethylene vinyl acetate copolymer (EVA) resin on one surface of a polyethylene terephthalate base film (PET) having a thickness of 100 μm. On the other side, an EVA resin layer having a thickness of 150 μm was formed by extrusion using the same ethylene vinyl acetate copolymer (EVA) resin. The glass transition temperature of this 150 μm EVA resin layer was −42 ° C.
A pressure-sensitive adhesive composition is applied onto a 50 μm-thick PET separator, dried, and this pressure-sensitive adhesive layer composition layer and the above-mentioned 150 μm EVA resin layer are laminated to form a pressure-sensitive adhesive having a thickness of 30 μm. A semiconductor wafer surface protecting adhesive tape having a layer was prepared.

The following tests were conducted on the semiconductor wafer surface protecting adhesive tapes produced in the above examples and comparative examples, and their performance was evaluated. The evaluation results are shown in Tables 1 to 3.

1. Measurement of glass transition temperature after crosslinking of intermediate resin layer (Test method)
Ethyl acetate was sprayed on the intermediate resin layer to swell the intermediate resin layer, and the intermediate resin layer after crosslinking was collected with a spatula. Thereafter, all the solvents were removed by vacuum drying, and then measured with a differential scanning calorimeter (DSC).

2. Production of semiconductor wafer with polyimide film A semiconductor wafer with a polyimide film was produced by the following method.
The thickness of the entire wafer is 725μm, and an 8-inch silicon semiconductor wafer is coated with non-photosensitive polyimide PIX-3400 (trade name, manufactured by Hitachi Chemical DuPont Microsystems Co., Ltd.) and edged with a spin coater. Coating was performed while rinsing so that the film thickness after drying was 6 μm. Thereafter, pre-baking was performed at 200 ° C. for 30 minutes, and main baking was performed at 350 ° C. for 1 hour to form a polyimide film having a thickness of 6 μm. Thus, an 8-inch semiconductor wafer having a total thickness of 725 μm was obtained.
Using this semiconductor wafer with a polyimide film, the following tests 3 to 5 were performed, and the performance was evaluated.

3. Thin film grindability test (test method)
1. Using DR8500II (trade name) manufactured by Nitto Seiki Co., Ltd. as the pasting machine The adhesive tape for protecting the surface of the semiconductor wafer prepared in Examples and Comparative Examples was bonded to a silicon semiconductor wafer with a polyimide film having a thickness of 725 μm. In this case, the parameters are controlled by a regulator attached to the apparatus, and the tape winding is 0.11 MPa, the tape feeding is 0.26 MPa, the separator is 0.20 MPa, the tape presser is 0.17 MPa, and the tape is stuck. The adhesive tape for semiconductor wafer surface protection was bonded on the conditions of 0.26 MPa. Thereafter, 25 wafers were each polished to a thickness of 50 μm, 30 μm, and 20 μm using a grinder having an inline mechanism (DFG8760 (trade name) manufactured by DISCO Corporation). Moreover, the final finishing was performed by dry polishing in order to improve the strength of the wafer.
(Evaluation)
The adhesive tape for protecting the surface of a semiconductor wafer produced in each example and each comparative example was evaluated. As a result, it determined as follows, (circle) and (triangle | delta) were set as the pass, and x was set as the disqualification.
There were almost no edge cracks and all 25 wafers could be ground: ○
Although some edge cracks were observed, the wafer could be ground without cracks, or 25 wafers had 1 to 2 cracks in the wafer: △
Three or more wafers broken: ×

4). Peel test (test method)
3. above. Twenty-five peelability tests were performed using a wafer with a polyimide film ground in a thin film grindability test, using a peeling machine (DFM2700 (trade name) manufactured by DISCO Corporation) attached to the grinder. The pressure-sensitive pressure-sensitive adhesive tape was peeled at 50 ° C., and the radiation-curing pressure-sensitive adhesive tape was measured at room temperature after irradiation with ultraviolet rays at 500 mJ / cm ² .
(Evaluation)
The adhesive tape for protecting the surface of a semiconductor wafer produced in each example and each comparative example was evaluated. As a result, the determination was made as follows, and ○ and Δ were regarded as acceptable.
All 25 tapes were peeled off from the wafer without any problem: ○
The tape could be peeled without damaging the wafer, but an error occurred more than once due to failure of peeling:
A wafer that was damaged during peeling, or a tape that could not be peeled from the wafer: ×

5. Conveyance test (test method)
3. above. In a thin film grinding test, an in-line device (DFG8760 (trade name) manufactured by DISCO Corporation and DFM2700 manufactured by DISCO Corporation) The product was transported from the back grinding process to the dicing die bonding film bonding process and the peeling process. The dicing die bond film used was FH-900-20 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and the bonding was performed at 60 ° C.
(Evaluation)
The adhesive tape for protecting the surface of a semiconductor wafer produced in each example and each comparative example was evaluated. As a result, it determined as follows and made (circle) the pass.
What could be transported without any adsorption error: ○
A suction error has occurred and a transport error has occurred: ×

6). Contamination test (test method)
Using a DR8500II (trade name) manufactured by Nitto Seiki Co., Ltd. as the pasting machine, the adhesive tape for protecting the surface of the semiconductor wafer produced in Examples and Comparative Examples was bonded to a silicon mirror wafer having a thickness of 725 μm. did. Thereafter, the pressure-sensitive adhesive tape was peeled off at 50 ° C., and the radiation-curable pressure-sensitive adhesive tape was peeled off at room temperature after irradiation with ultraviolet rays of 500 mJ / cm ² .
Next, the element ratio of contaminants on the wafer surface after peeling the semiconductor wafer surface protecting adhesive tape was measured by XPS (X-ray photoelectron spectroscopy). The amount of increase in carbon derived from transfer contaminants from the adhesive tape was calculated as mol% compared to a blank wafer to which the adhesive tape was not bonded. XPS was measured under the following conditions.
X-ray source: MgKα, X-ray Take off angle: 45 °,
Measurement area: 1.1mmφ
(Evaluation)
The adhesive tape for protecting the surface of a semiconductor wafer produced in each example and each comparative example was evaluated. As a result, it determined as follows and made (circle) the pass.
C (carbon) amount (atomic%) was 25 or less: ○
C (carbon) content (atomic%) greater than 25: x

7). Restitution coefficient and resilience measurement test (test method)
Using a loop step tester (trade name) manufactured by Toyo Seiki Seisakusho Co., Ltd., the restitution coefficient γ and the repulsion force α were measured.
The semiconductor wafer surface protecting adhesive tape prepared in each Example and each Comparative Example was cut into a width of 1 cm and placed on a loop stiffness tester. At that time, a circular loop having a loop length of 50 mm was formed in the vicinity of the center of the belt-like adhesive tape having a loop length of 50 mm or more, and the load applied when the circular loop was pushed in from the outside by 5 mm was measured. The load obtained at this time was converted to the width of the pressure-sensitive adhesive tape, and the value displayed in mN / mm was defined as the repulsive force α. A value obtained by dividing the repulsive force α by the square of the thickness of the base resin film of the adhesive tape was defined as a restitution coefficient γ.
(Evaluation)
The adhesive tape for protecting the surface of a semiconductor wafer produced in each example and each comparative example was evaluated. As a result, the case where the restitution coefficient was 100 mN / mm ³ or more and the repulsion force was 13 mN / mm or less was regarded as acceptable. Moreover, the repulsive force was 20 mN / mm or more, and measurement was impossible.

8. Adhesive strength measurement test at 25 ° C and 50 ° C (test method)
Among the pressure-sensitive adhesive tapes for protecting the semiconductor wafer surface produced in each example and each comparative example, the adhesive strength at 50 ° C. was measured.
Three test pieces each having a width of 25 mm and a length of 300 mm were collected from the adhesive tape, and finished with a No. 280 water-resistant abrasive paper specified in JIS R 6253. The thickness specified in JIS G 4305 was 1.5 mm to 2. A 2 kg rubber roller was pressure-bonded on a 0 mm SUS304 steel plate by three reciprocations. After standing for 1 hour, the adhesive strength of the test piece of the adhesive tape pressure-bonded to the SUS plate was measured at 50 ° C. and a relative humidity of 49% using a tensile tester specified in JIS B 7721. The measurement was performed by a 180-degree peeling method, and the tensile speed at this time was 300 mm / min.

9. Measurement of tensile elongation at break in longitudinal (MD) and transverse (TD) directions (test method)
A sample of an adhesive tape for protecting the surface of a semiconductor wafer is punched out with a dumbbell according to dumbbell shape No. 1 (JIS K 6301), and the winding direction with respect to the roll is set to the vertical direction (MD), and the width direction is set to the horizontal direction (TD). Each sample was subjected to n = 3 sampling, and a line was drawn at a place 20 mm above and below from the center of each sample sampled. Using a tensile tester (JIS B 7721), the sample was pulled at a tensile speed of 300 mm / min, and the elongation at break in the line was measured. The average value of three measurements was used as the actual value, and the difference between the tensile rupture elongation in the longitudinal direction and the tensile rupture elongation in the transverse direction was calculated.

As shown in Tables 1 to 3, in Comparative Example 1, the difference in tensile elongation at break between the longitudinal direction and the transverse direction exceeded 35%, and the adhesive tape for protecting the semiconductor wafer surface was warped. became. In Comparative Example 2, since the coefficient of restitution is too small, the warpage of the wafer itself cannot be corrected, the transportability is rejected, and the difference in tensile breaking elongation exceeds 35%, so that the tape itself is also warped. It became. In Comparative Example 3, since PET was used for the base resin film, the transportability was acceptable, but since there was no intermediate resin layer, the cushioning property was insufficient during thin film grinding, and the thin film grindability was poor and edge cracks occurred. As a result. Furthermore, since the repulsive force is high, the tape itself is not easily bent when the tape is peeled off, resulting in the wafer cracking or peeling failure during peeling. In Comparative Examples 4 and 5, the coefficient of restitution was too small and the transportability was rejected. Since the core material PET was used in Comparative Example 6, there was no problem in transportability, but the thin film grindability was poor, and many cracks were generated during thin film grinding.
On the other hand, it was found that all of the semiconductor wafer surface protecting adhesive tapes of Examples 1 to 11 had acceptable results in the conveyance test and thin film grinding test, and could be peeled off without any problem. In particular, Example 1, Example 3, Example 4 and Example 10 resulted in excellent thin film grindability and transportability. When polyimide is used as the base material, the performance is good, but the cost is high. Therefore, Example 1, Example 3 and Example 4 are the best overall results.

According to the present invention, a thin film wafer having a thickness of 100 μm or less can be obtained by grinding the back surface of the semiconductor wafer while the adhesive tape for protecting the surface of the semiconductor wafer is bonded to the semiconductor wafer. Therefore, this invention is suitable as an adhesive tape for surface protection used by bonding to the surface of a semiconductor wafer.

While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

This application claims priority based on Japanese Patent Application No. 2009-291497 filed in Japan on December 22, 2009 and Japanese Patent Application No. 2010-220068 filed on September 29, 2010 in Japan. All of which are hereby incorporated herein by reference in their entirety.

DESCRIPTION OF SYMBOLS 1 Base resin film 2 Adhesive layer 3 Intermediate resin layer 20 Adhesive tape for semiconductor wafer surface protection

Claims

For protecting a semiconductor wafer surface, having a base resin film and an adhesive layer directly through an intermediate resin layer in which a base resin component containing an acrylic polymer and / or polyurethane acrylate is crosslinked on the base resin film An adhesive tape, the repulsive force α per unit width obtained from the load load of the loop stiffness measured on the adhesive tape for protecting a semiconductor wafer surface under the following conditions (a) to (d): The restitution coefficient γ divided by the square of β is 100 mN / mm 3 or more, the repulsion force α is 13 mN / mm or less, and the difference in tensile breaking elongation between the longitudinal direction and the transverse direction is 35% or less. An adhesive tape for protecting the surface of a semiconductor wafer.
(A) Equipment Loop step tester (trade name, manufactured by Toyo Seiki Co., Ltd.)
(B) Loop (test piece) shape Length 50 mm or more, width 10 mm
(C) Indenter pushing speed 3.3 mm / sec
(D) Indenter push-in amount Push in 5 mm from the point when the indenter contacts the loop.
2. The adhesive tape for protecting a semiconductor wafer surface according to claim 1, wherein the acrylic polymer of the intermediate resin layer has a hydroxyl group and a carboxyl group.
2. The adhesive tape for protecting a semiconductor wafer surface according to claim 1, wherein the polyurethane acrylate of the intermediate resin layer has a hydroxyl group and a carboxyl group.
The adhesive tape for protecting a semiconductor wafer surface according to any one of claims 1 to 3, wherein the glass transition temperature after crosslinking of the intermediate resin layer is -10 ° C to 30 ° C.
The adhesive tape for protecting a semiconductor wafer surface according to any one of claims 1 to 4, wherein the base resin film is a polyester resin film.
6. The adhesive tape for protecting a semiconductor wafer surface according to claim 5, wherein the polyester resin film is a polyethylene terephthalate film.
The adhesive tape for protecting a semiconductor wafer surface according to claim 5 or 6, wherein the polyester resin film has a thickness of 25 to 75 µm.
The adhesive tape for protecting a semiconductor wafer surface is a pressure-sensitive adhesive tape, and has an adhesive force to a SUS polished surface at 20 to 25 ° C. of 0.5 N / 25 mm or more, and an adhesive force to a SUS polished surface at 50 ° C. is 0. The adhesive tape for protecting a semiconductor wafer surface according to any one of claims 1 to 7, wherein the pressure-sensitive adhesive tape is 5 N / 25 mm or less.
9. The adhesive tape for protecting a semiconductor wafer surface according to claim 8, wherein the weight average molecular weight of the base resin constituting the adhesive layer is 1 million or more.
The adhesive tape for protecting a surface of a semiconductor wafer according to any one of claims 1 to 7, wherein the adhesive layer has a low adhesive strength when irradiated with radiation.
The pressure-sensitive adhesive layer is made of a base resin composed mainly of a polymer containing as a constituent unit an acrylic monomer having at least one radiation-polymerizable carbon-carbon double bond-containing group with respect to the main chain. The pressure-sensitive adhesive tape for protecting a surface of a semiconductor wafer according to claim 10.