WO2015190230A1 - Dicing sheet - Google Patents

Abstract

This dicing sheet (1) is provided with a substrate (2), an adhesive layer (3) layered at one surface side of the substrate (2), and a peeling sheet (6) layered at the surface side of the adhesive layer (3) at the reverse of the substrate (2). The arithmetic mean roughness (Ra1) of the second surface of the substrate (2) is at least 0.2 μm, and the arithmetic means roughness (Ra2) of the second surface of the substrate (2) after the dicing sheet (1) is heated for two hours at 130°C is no greater than 0.25 μm.

Description

Dicing sheet

The present invention relates to a dicing sheet that can be used for dicing a workpiece such as a semiconductor wafer, particularly stealth dicing.
This application claims priority based on Japanese Patent Application No. 2014-120034 filed in Japan on June 10, 2014, the contents of which are incorporated herein by reference.

When manufacturing a workpiece made of a piece of semiconductor chip or the like from a workpiece such as a semiconductor wafer, conventionally, the workpiece is cut with a rotary blade while spraying a liquid for cleaning or the like on the workpiece. In general, blade dicing is performed to obtain a piece-like body. However, in recent years, stealth dicing (registered trademark; the same applies hereinafter) processing that can be divided into pieces in a dry process has been adopted (Patent Document 1).

For example, in Patent Document 2, a laminated pressure-sensitive adhesive sheet (two layers of pressure-sensitive adhesive sheets composed of a base material and a pressure-sensitive adhesive layer) is attached to an ultrathin semiconductor wafer, and the laminated pressure-sensitive adhesive sheet is used from the side of the laminated pressure-sensitive adhesive sheet. After irradiating the semiconductor wafer with laser light and forming a modified portion inside the semiconductor wafer, the adhesive sheet is expanded to divide the semiconductor wafer along the dicing line and produce semiconductor chips. A stealth dicing method is disclosed.

Japanese Patent No. 3762409 JP 2007-123404 A

As described above, when irradiating a workpiece with laser light, the laser beam needs to pass through the adhesive sheet to reach the workpiece, and therefore the adhesive sheet is required to have laser beam transparency.

Incidentally, a release sheet is often laminated on the side of the dicing sheet opposite to the base material of the adhesive layer in order to protect the adhesive layer. When such a dicing sheet is unwound from the roll state, the surface of the rolled dicing sheet opposite to the adhesive layer of the base material and the surface of the release sheet opposite to the adhesive layer are in close contact with each other, thereby blocking. It may occur, and a feeding failure from the roll may occur, or the substrate may be transferred to a release sheet on which the substrate is wound, so that the workpiece cannot be attached.

The present invention has been made in view of the actual situation as described above, and can suppress the occurrence of blocking when the dicing sheet is unwound from the roll-up state, and transmits laser light when irradiated with laser light. An object of the present invention is to provide a dicing sheet having excellent properties.

In order to achieve the above object, first, the present invention provides a base material, a pressure-sensitive adhesive layer laminated on the first surface side of the base material, and a surface of the pressure-sensitive adhesive layer opposite to the base material. A dicing sheet including a release sheet laminated on the side, wherein the arithmetic average roughness (Ra1) of the second surface of the base material is 0.2 μm or more, and the second surface of the base material The dicing sheet is characterized in that the arithmetic average roughness (Ra2) after heating the dicing sheet at 130 ° C. for 2 hours is 0.25 μm or less (Invention 1). In the present specification, the “sheet” includes, for example, a concept of a long tape or the like.

According to the said invention (invention 1), when the dicing sheet is wound up in a roll shape, the second surface of the base material and the release sheet that comes into contact with the second surface of the base material are hardly adhered, Blocking is unlikely to occur when the rolled-up dicing sheet is fed out. Further, after the dicing sheet is heated, when the laser beam is irradiated from the second surface side of the substrate, the laser beam is transmitted through the dicing sheet without being disturbed by the unevenness of the second surface of the substrate, Efficiently reaches (semiconductor wafer) and has excellent laser beam transmissivity.

In the above invention (Invention 1), the arithmetic average roughness (Ra2) after the heating on the second surface of the substrate is preferably smaller than the arithmetic average roughness (Ra1) (Invention 2).

In the above inventions (Inventions 1 and 2), the base material preferably has a melting point of 90 to 180 ° C. (Invention 3).

In the above inventions (Inventions 1 to 3), the storage elastic modulus of the substrate at 130 ° C. is preferably 1 to 100 MPa (Invention 4).

In the above inventions (Inventions 1 to 4), the light transmittance of the substrate after the heating at a wavelength of 1064 nm is preferably 40% or more (Invention 5).

In the above inventions (Inventions 1 to 5), the substrate is preferably a film composed of a copolymer of ethylene and propylene (Invention 6).

In the above inventions (Inventions 1 to 6), the dicing sheet preferably includes a jig pressure-sensitive adhesive layer laminated on a peripheral edge of the pressure-sensitive adhesive layer on the side opposite to the base material side (Invention 7). .

According to the dicing sheet according to the present invention, it is possible to suppress the occurrence of blocking when the dicing sheet is unwound from the state of being wound up in a roll shape, and is excellent in laser light transmittance when irradiated with laser light.

It is sectional drawing of the dicing sheet which concerns on one Embodiment of this invention. It is sectional drawing which shows the usage example of the dicing sheet which concerns on one Embodiment of this invention, specifically a laminated structure. It is sectional drawing of the dicing sheet which concerns on other embodiment of this invention. It is a top view of the dicing sheet produced in the Example.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a cross-sectional view of a dicing sheet according to an embodiment of the present invention. As shown in FIG. 1, the dicing sheet 1 according to the present embodiment includes a base material 2, a pressure-sensitive adhesive layer 3 laminated on the first surface side of the base material 2 (upper side in FIG. 1), and a pressure-sensitive adhesive. And a release sheet 6 laminated on the layer 3. The release sheet 6 is peeled and removed when the dicing sheet 1 is used, and protects the pressure-sensitive adhesive layer 3 until then. Here, the surface of the base material 2 on the pressure-sensitive adhesive layer 3 side is referred to as a “first surface”, and the opposite surface (the lower surface in FIG. 1) is referred to as a “second surface”.

The dicing sheet 1 according to the present embodiment is used, as an example, for holding a semiconductor wafer during dicing of a semiconductor wafer as a workpiece, but is not limited thereto.

The dicing sheet 1 according to the present embodiment is usually formed in a long shape, wound into a roll, and used in a roll-to-roll manner.

1. Base Material The arithmetic average roughness (Ra1) on the second surface of the base material 2 (hereinafter sometimes referred to as “the back surface of the base material 2”) is 0.2 μm or more. The arithmetic average roughness (Ra2) on the back surface of the substrate 2 after heating the dicing sheet 1 at 130 ° C. for 2 hours and cooling to room temperature (hereinafter sometimes simply referred to as “after heating”) is 0. 25 μm or less. In addition, the arithmetic mean roughness (Ra1) of the back surface of the base material 2 is the arithmetic average roughness of the back surface of the base material 2 before heating at 130 ° C. for 2 hours, and is hereinafter referred to as “arithmetic average roughness before heating”. (Ra1) ". The arithmetic average roughness (Ra1) before heating and the arithmetic average roughness (Ra2) after heating are measured based on JIS B0601: 2001, and the details of the measuring method are as shown in the test examples described later. is there.

It should be noted that when the rolled dicing sheet 1 is unwound, it is before heating, and the laser beam irradiation of stealth dicing is performed after heating.

Arithmetic average roughness (Ra1) before heating of the back surface of the base material 2 is 0.2 μm or more, so that the back surface of the base material 2 and the surface opposite to the adhesive layer 3 of the release sheet 6 are in close contact with each other. Difficult. Thereby, blocking is hard to generate | occur | produce when unwinding the roll-shaped dicing sheet 1 wound up. Therefore, it is possible to suppress the occurrence of feeding failure due to blocking or the transfer of the workpiece 2 to the release sheet 6 on which the base material 2 is wound and the attachment of the workpiece to be impossible.

From the above viewpoint, the arithmetic average roughness (Ra1) before heating on the back surface of the substrate 2 is preferably 0.25 μm or more, and particularly preferably 0.30 μm or more.

Here, the upper limit of the arithmetic average roughness (Ra1) before heating on the back surface of the substrate 2 is preferably 1.0 μm or less, particularly preferably 0.8 μm or less, and more preferably 0.7 μm. The following is preferable. If the arithmetic average roughness (Ra1) before heating exceeds 1.0 μm, it may be difficult to satisfy the arithmetic average roughness (Ra2) after heating described above.
That is, the arithmetic average roughness (Ra1) before heating on the back surface of the substrate 41 is preferably in the range of 0.25 to 1.0 μm, and more preferably in the range of 0.30 to 0.7 μm. .

On the other hand, when the arithmetic average roughness (Ra2) after heating under the above conditions on the back surface of the base material 2 is 0.25 μm or less, the laser beam was irradiated from the back side of the base material 2 after the dicing sheet 1 was heated. Sometimes, the laser beam passes through the dicing sheet 1 without being disturbed by the unevenness on the back surface of the base material 2, efficiently reaches the workpiece (semiconductor wafer), and has excellent laser beam transparency. Therefore, it is excellent in the work division property by stealth dicing.

From the above viewpoint, the arithmetic average roughness (Ra2) after heating on the back surface of the substrate 2 is preferably 0.20 μm or less, and particularly preferably 0.10 μm or less.

Here, the lower limit of the arithmetic average roughness (Ra2) after heating on the back surface of the substrate 2 is not particularly limited as long as the arithmetic average roughness (Ra1) before heating is satisfied. However, it is usually 0.001 μm or more, preferably 0.01 μm or more.
That is, the arithmetic average roughness (Ra2) after heating on the back surface of the substrate 41 is preferably in the range of 0.001 to 0.20 μm, and more preferably in the range of 0.01 to 0.10 μm. .

Moreover, in the base material 2, it is preferable that the arithmetic average roughness (Ra2) after the heating by the said conditions in the back surface of the base material 2 is smaller than the arithmetic average roughness (Ra1) before a heating. By setting in this way, both the blocking suppression effect before heating and the laser beam transparency after heating can be made more excellent.

Although it does not specifically limit as a method of adjusting arithmetic mean roughness (Ra1) before the heating in the back surface of the base material 2, Generally, the roll surface used when forming the resin film which comprises the base material 2 The surface roughness can be changed, sandblasting, or blending of fillers that melt and become flat by heating can be adjusted.

On the other hand, as a method for adjusting the arithmetic average roughness (Ra2) after heating on the back surface of the base material 2, the base material 2 is a resin film having a melting point within a predetermined range (a film mainly composed of a resin-based material). In particular, it is preferable to form a resin film having a melting point within a predetermined range and a storage elastic modulus at 130 ° C. within a predetermined range.

The melting point of the substrate 2 is preferably 90 to 180 ° C, particularly preferably 100 to 160 ° C, and more preferably 110 to 150 ° C. When the melting point of the base material 2 is in the above range, the arithmetic average roughness (Ra2) after heating on the back surface of the base material 2 can be easily adjusted to the above range. If the melting point of the substrate 2 is less than 90 ° C, the substrate 2 may be completely melted during heating. On the other hand, when the melting point of the base material 2 exceeds 180 ° C., the arithmetic average roughness on the back surface of the base material 2 may not be changed by heating at 130 ° C. for 2 hours. In addition, the said melting | fusing point was measured based on JISK7121 (ISO3146), and the detail of the measuring method is as showing to the test example mentioned later.

Although there is no restriction | limiting in particular in the method of adjusting the melting | fusing point of the base material 2, Generally, it can adjust mainly by melting | fusing point of the resin material to be used. Further, the base material 2 can be adjusted to an arbitrary melting point by mixing a plurality of resin materials having different melting points or by copolymerizing a plurality of monomers.

The storage elastic modulus of the substrate 2 at 130 ° C. is preferably 1 to 100 MPa, particularly preferably 2 to 80 MPa, and further preferably 5 to 50 MPa. When the storage elastic modulus at 130 ° C. of the base material 2 is in the above range, the arithmetic average roughness (Ra2) after heating on the back surface of the base material 2 can be easily adjusted to the above range. If the storage elastic modulus at 130 ° C. of the base material 2 is less than 1 MPa, the base material 2 may be greatly deformed during the heat treatment, and the workpiece may not be held. On the other hand, when the storage elastic modulus at 130 ° C. of the substrate 2 exceeds 100 MPa, the arithmetic average roughness on the back surface of the substrate 2 may not be changed even by heating at 130 ° C. for 2 hours. In addition, the measuring method of the said storage elastic modulus is as showing to the test example mentioned later.

The method for adjusting the storage elastic modulus of the substrate 2 at 130 ° C. is not particularly limited, but in general, it can be adjusted mainly by the storage elastic modulus of the resin material to be used. In general, even if the chemical structure is the same, if the molecular weight is high, the storage elastic modulus tends to increase, and the storage elastic modulus tends to increase due to cross-linking and narrow molecular weight distribution. Based on this tendency, the base material 2 can be adjusted to an arbitrary storage elastic modulus.

When laser light having a wavelength of 1064 nm is used in stealth dicing or the like, the light transmittance at a wavelength of 1064 nm after heating the substrate 2 is preferably 40% or more, particularly preferably 50% or more, and further 60 % Or more is preferable. Since the light transmittance at a wavelength of 1064 nm after the heating of the base material 2 is in the above range, the work can be easily divided by stealth dicing. In this embodiment, when the arithmetic mean roughness (Ra2) after heating on the back surface of the base material 2 is in the above range, the above light transmittance can be realized. The higher the light transmittance at a wavelength of 1064 nm after heating the substrate 2, the better, but the light transmittance that can be realized is about 99% at the maximum.

Specific examples of the resin film constituting the substrate 2 include polyethylene films such as low density polyethylene (LDPE) film, linear low density polyethylene (LLDPE) film, and high density polyethylene (HDPE) film, polypropylene film, and ethylene-propylene. Polyolefin films such as copolymer film, polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, norbornene resin film; ethylene-vinyl acetate copolymer film, ethylene- (meth) acrylic acid copolymer Polymer films, ethylene copolymer films such as ethylene- (meth) acrylate copolymer films; polyvinyl chloride films such as polyvinyl chloride films and vinyl chloride copolymer films Arm, polyethylene terephthalate film, a polyester film such as polyethylene terephthalate and polybutylene terephthalate film; polyurethane film; polyimide film; polystyrene films; polycarbonate films; and fluorine resin film. In addition, modified films such as these crosslinked films and ionomer films are also used. Furthermore, a laminated film in which a plurality of the above films are laminated may be used. In addition, “(meth) acrylic acid” in the present specification means both acrylic acid and methacrylic acid. The same applies to other similar terms.

In the case of a laminated film, for example, a film whose arithmetic average roughness changes before and after heating is disposed on the back side of the base material 2, and the adhesive layer 3 side of the base material 2 has heat resistance and does not deform even at high temperatures. It is preferable to arrange a film.

Among the above, polyolefin film is preferable, polyethylene film, polypropylene film and ethylene-propylene copolymer film are particularly preferable, and ethylene-propylene copolymer film is more preferable. According to these resin films, the above-described physical properties are easily satisfied. In particular, in the case of an ethylene-propylene copolymer film, the above-described physical properties are satisfied by adjusting the copolymerization ratio of the ethylene monomer and the propylene monomer. easy. Moreover, these resin films are preferable also from a viewpoint of workpiece sticking property or chip peelability.

For the purpose of improving the adhesiveness with the pressure-sensitive adhesive layer 3 laminated on the surface, the resin film is subjected to surface treatment by an oxidation method, a concavo-convex method, or a primer treatment on one side or both sides as desired. Can do. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, ultraviolet irradiation treatment, and the like. And a thermal spraying method.

In addition, the base material 2 may contain various additives, such as a coloring agent, a flame retardant, a plasticizer, an antistatic agent, a lubricant, a filler, in the said resin film.

The thickness of the substrate 2 is not particularly limited as long as it can function properly in each step in which the dicing sheet 1 is used, but is preferably 20 to 450 μm, more preferably 25 to 400 μm, It is preferably 50 to 350 μm.

2. Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer 3 included in the dicing sheet 1 according to the present embodiment may be made of a non-energy ray-curable pressure-sensitive adhesive or may be made of an energy-ray-curable pressure-sensitive adhesive. As the non-energy ray curable pressure-sensitive adhesive, those having desired adhesive strength and removability are preferable. For example, acrylic pressure-sensitive adhesive, rubber-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive, and polyester-based pressure-sensitive adhesive Polyvinyl ether-based pressure-sensitive adhesives can be used. Among these, in the dicing process or the like, an acrylic pressure-sensitive adhesive that can effectively prevent the workpiece or workpiece from falling off is preferable.

On the other hand, since the adhesive strength of the energy ray curable pressure-sensitive adhesive is reduced by energy ray irradiation, when the workpiece or workpiece and the dicing sheet 1 are to be separated, they can be easily separated by irradiation with energy rays. it can.

The energy ray-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 3 may be mainly composed of a polymer having energy ray-curability, or a polymer having no energy ray-curability and an energy ray-curable property. The main component may be a polyfunctional monomer and / or a mixture with an oligomer.

The case where the energy ray-curable pressure-sensitive adhesive is mainly composed of a polymer having energy ray-curability will be described below.

The polymer having energy ray curability is a (meth) acrylic acid ester (co) polymer (A) (hereinafter referred to as “energy ray”) in which a functional group having energy ray curability (energy ray curable group) is introduced into the side chain. It may be referred to as “curable polymer (A)”). This energy ray curable polymer (A) includes a (meth) acrylic copolymer (a1) having a functional group-containing monomer unit, and an unsaturated group-containing compound (a2) having a substituent bonded to the functional group. It is preferable that it is obtained by making it react.

The acrylic copolymer (a1) is composed of a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth) acrylic acid ester monomer or a derivative thereof.

The functional group-containing monomer as a constituent unit of the acrylic copolymer (a1) is a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, an amino group, a substituted amino group, or an epoxy group in the molecule. It is preferable that

More specific examples of the functional group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

Examples of the (meth) acrylic acid ester monomer constituting the acrylic copolymer (a1) include alkyl (meth) acrylates having 1 to 20 carbon atoms in the alkyl group, cycloalkyl (meth) acrylates, and benzyl (meth) acrylates. Is used. Among these, particularly preferred are alkyl (meth) acrylates having an alkyl group having 1 to 18 carbon atoms, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) ) Acrylate, 2-ethylhexyl (meth) acrylate and the like are used.

In the acrylic copolymer (a1), the structural unit derived from the functional group-containing monomer is usually 3 to 100% by mass, preferably 4 to 80%, based on the total mass of the acrylic copolymer (a1). More preferably, it is contained in a proportion of 5 to 40% by mass, and the structural unit derived from the (meth) acrylic acid ester monomer or derivative thereof is usually based on the total mass of the acrylic copolymer (a1). It is contained in a proportion of 0 to 97% by mass, preferably 60 to 95% by mass.

The acrylic copolymer (a1) can be obtained by copolymerizing a functional group-containing monomer as described above with a (meth) acrylic acid ester monomer or a derivative thereof in a conventional manner. Dimethylacrylamide, vinyl formate, vinyl acetate, styrene and the like may be copolymerized.

By reacting the acrylic copolymer (a1) having the functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a substituent bonded to the functional group, an energy beam curable polymer (A ) Is obtained.

The substituent of the unsaturated group-containing compound (a2) can be appropriately selected according to the type of functional group of the functional group-containing monomer unit of the acrylic copolymer (a1). For example, when the functional group is a hydroxyl group, an amino group or a substituted amino group, the substituent is preferably an isocyanate group or an epoxy group, and when the functional group is an epoxy group, the substituent is an amino group, a carboxyl group or an aziridinyl group. preferable.

Further, the unsaturated group-containing compound (a2) contains 1 to 5, preferably 1 to 2, energy-polymerizable carbon-carbon double bonds per molecule. Specific examples of such unsaturated group-containing compound (a2) include, for example, 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1- ( Bisacryloyloxymethyl) ethyl isocyanate; acryloyl monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth) acrylate; diisocyanate compound or polyisocyanate compound, polyol compound, and hydroxyethyl (meth) Acryloyl monoisocyanate compound obtained by reaction with acrylate; glycidyl (meth) acrylate; (meth) acrylic acid, 2- (1 -Aziridinyl) ethyl (meth) acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline and the like.

The unsaturated group-containing compound (a2) is usually used in a ratio of 10 to 100 equivalents, preferably 20 to 95 equivalents per 100 equivalents of the functional group-containing monomer of the acrylic copolymer (a1).

In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), depending on the combination of the functional group and the substituent, the reaction temperature, pressure, solvent, time, presence of catalyst, catalyst Can be selected as appropriate. As a result, the functional group present in the acrylic copolymer (a1) reacts with the substituent in the unsaturated group-containing compound (a2), so that the unsaturated group is contained in the acrylic copolymer (a1). It introduce | transduces into a side chain and an energy-beam curable polymer (A) is obtained.

The weight average molecular weight of the energy ray curable polymer (A) thus obtained is preferably 10,000 or more, particularly preferably 150,000 to 1,500,000, and more preferably 200,000 to 1,000,000. Is preferred. In addition, the weight average molecular weight (Mw) in this specification is the value of polystyrene conversion measured by the gel permeation chromatography method (GPC method).

Even when the energy ray-curable pressure-sensitive adhesive has a polymer having energy ray-curability as a main component, the energy ray-curable pressure-sensitive adhesive further contains an energy ray-curable monomer and / or oligomer (B). You may contain.

As the energy ray-curable monomer and / or oligomer (B), for example, an ester of a polyhydric alcohol and (meth) acrylic acid or the like can be used.

Examples of the energy ray-curable monomer and / or oligomer (B) include monofunctional acrylic acid esters such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, penta Erythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol Polyfunctional acrylic esters such as di (meth) acrylate and dimethyloltricyclodecane di (meth) acrylate, polyester oligo (meth) acrylate, polyurethane oligo (meta Acrylate, and the like.

When the energy ray curable monomer and / or oligomer (B) is blended, the content of the energy ray curable monomer and / or oligomer (B) in the energy ray curable adhesive is determined by the energy ray curable pressure sensitive adhesive. The total mass is preferably 5 to 80% by mass, more preferably 20 to 60% by mass.

Here, when using ultraviolet rays as an energy ray for curing the energy ray curable resin composition, it is preferable to add a photopolymerization initiator (C), and by using this photopolymerization initiator (C). The polymerization curing time and the amount of light irradiation can be reduced.

Specific examples of the photopolymerization initiator (C) include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyldiphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4 6-trimethylbenzyldiphenyl) phosphine oxide, 2-benzothiazole-N, N-diethyldithiocarbamate, oligo {2-hydroxy-2-me Le-1- [4- (1-propenyl) phenyl] propanone}, and 2,2-dimethoxy-1,2-and the like. These may be used alone or in combination of two or more.

The photopolymerization initiator (C) is energy beam curable copolymer (A) (when energy beam curable monomer and / or oligomer (B) is blended, energy beam curable copolymer (A). , And a total amount of energy ray-curable monomer and / or oligomer (B) of 100 parts by mass) in an amount of 0.1 to 10 parts by mass, in particular 0.5 to 6 parts by mass with respect to 100 parts by mass. Is preferably used.

In the energy ray-curable pressure-sensitive adhesive, other components may be appropriately blended in addition to the above components. Examples of other components include a polymer component or oligomer component (D) that does not have energy beam curability, and a crosslinking agent (E).

Examples of the polymer component or oligomer component (D) having no energy ray curability include polyacrylates, polyesters, polyurethanes, polycarbonates, polyolefins, etc., and polymers having a weight average molecular weight (Mw) of 3,000 to 2.5 million. Or an oligomer is preferable.

As the crosslinking agent (E), a polyfunctional compound having reactivity with the functional group of the energy beam curable copolymer (A) or the like can be used. Examples of such polyfunctional compounds include, for example, isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, Examples thereof include ammonium salts and reactive phenol resins.

By blending these other components (D) and (E) into the energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive layer 3 is hardened and peelable before curing, strength after curing, and adhesion to other layers. , Storage stability and the like can be improved. The blending amount of these other components is not particularly limited, and is appropriately determined in the range of 0 to 40 parts by mass with respect to 100 parts by mass of the energy beam curable copolymer (A).

Next, the case where the energy ray-curable adhesive is mainly composed of a mixture of a polymer component having no energy ray curability and an energy ray-curable polyfunctional monomer and / or oligomer will be described below.

As the polymer component having no energy beam curability, for example, the same components as those of the acrylic copolymer (a1) described above can be used. The content of the polymer component having no energy beam curability in the energy beam curable resin composition is preferably 20 to 99.9% by mass with respect to the total mass of the energy beam curable resin composition, In particular, it is preferably 30 to 80% by mass.

As the energy ray-curable polyfunctional monomer and / or oligomer, the same one as the above-mentioned component (B) is selected. The blending ratio of the polymer component having no energy ray curability and the energy ray curable polyfunctional monomer and / or oligomer is 10 to 150 parts by mass of the polyfunctional monomer and / or oligomer with respect to 100 parts by mass of the polymer component. The amount is preferably 25 to 100 parts by mass.

Also in this case, the photopolymerization initiator (C) and the crosslinking agent (E) can be appropriately blended as described above.

The thickness of the pressure-sensitive adhesive layer 3 is not particularly limited as long as it can function properly in each process in which the dicing sheet 1 is used. Specifically, the thickness of the pressure-sensitive adhesive layer 3 is preferably 1 to 50 μm, particularly preferably 2 to 30 μm, and further preferably 3 to 20 μm.

3. Release Sheet The release sheet 6 in the present embodiment protects the pressure-sensitive adhesive layer 3 until the dicing sheet 1 is used. The release sheet 6 in the present embodiment is directly laminated on the pressure-sensitive adhesive layer 3, but is not limited to this, and other layers (such as a die bonding film) are laminated on the pressure-sensitive adhesive layer 3, A release sheet 6 may be laminated on the other layer.

The configuration of the release sheet 6 is arbitrary, and examples include a plastic film that has been subjected to a release treatment with a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, for example, silicone-based, fluorine-based, long-chain alkyl-based, and the like can be used, and among these, a silicone-based material that can provide inexpensive and stable performance is preferable. The thickness of the release sheet 6 is not particularly limited, but is usually about 20 to 250 μm.

4). Manufacturing method of dicing sheet In order to manufacture the dicing sheet 1, as an example, an application for the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 3 and optionally a solvent on the release surface of the release sheet 6. An adhesive is applied and dried to form the pressure-sensitive adhesive layer 3. Then, the base material 2 is crimped | bonded to the exposed surface of the adhesive layer 3, and the dicing sheet 1 which consists of the base material 2, the adhesive layer 3, and the peeling sheet 6 is obtained.

It is preferable that the pressure-sensitive adhesive layer 3 in the present embodiment can be attached to a jig such as a ring frame. In this case, when the pressure-sensitive adhesive layer 3 is made of an energy beam-curable pressure-sensitive adhesive, it is preferable not to cure the energy beam-curable pressure-sensitive adhesive. Thereby, the adhesive force with respect to jigs, such as a ring frame, can be maintained highly.

The laminated body of the base material 2 and the pressure-sensitive adhesive layer 3 may have a desired shape, for example, by inserting a cutting blade from the side of the first release sheet or the second release sheet or half-cutting by laser irradiation, as desired. You may form in circular shapes etc. corresponding to a workpiece | work (semiconductor wafer). In this case, an excess portion generated by the half cut may be removed as appropriate.

5. Method for Using Dicing Sheet As an example using the dicing sheet 1 according to the present embodiment, a method for manufacturing a chip from a semiconductor wafer as a workpiece will be described below.

First, the rolled-up dicing sheet 1 is unwound and the adhesive layer 3 of the dicing sheet 1 is attached to the semiconductor wafer 7 and the ring frame 8 as shown in FIG.

In the dicing sheet 1 according to the present embodiment, since the arithmetic average roughness (Ra1) before heating of the back surface of the substrate 2 is 0.2 μm or more, blocking is unlikely to occur during the above-described feeding, so that feeding failure occurs. Or it becomes impossible to attach a workpiece.

Thereafter, a laminated structure having a configuration in which the semiconductor wafer 7 is laminated on the surface of the expandable dicing sheet 1 on the pressure-sensitive adhesive layer 3 side (hereinafter, sometimes referred to as “laminated structure L”) is obtained. The laminated structure L shown in FIG. 2 further includes a ring frame 8.

The dicing sheet 1 is subjected to heat treatment. The heating temperature at this time is preferably 50 to 200 ° C., particularly 90 to 150 ° C., and the heating time is preferably 0.1 to 10 hours, particularly 1 to 3 hours. In the dicing sheet 1 according to the present embodiment, the arithmetic average roughness (Ra2) of the back surface of the substrate 2 is 0.25 μm or less by the heat treatment.

Next, the laminated structure L is subjected to a stealth dicing process. Specifically, the laminated structure L is installed in a split processing laser irradiation apparatus, the position of the surface of the semiconductor wafer 7 is detected, and then laser light is applied to the semiconductor wafer 7 via the dicing sheet 1. Irradiation forms a modified layer in the semiconductor wafer 7. Thereafter, an expanding process for extending the dicing sheet 1 is performed to apply a force (tensile force in the main surface direction) to the semiconductor wafer 7. As a result, the semiconductor wafer 7 adhered to the dicing sheet 1 is divided to obtain chips. Thereafter, a chip is picked up from the dicing sheet 1 using a pickup device.

In the dicing sheet 1 according to the present embodiment, the arithmetic average roughness (Ra2) after heating of the back surface of the base material 2 is 0.25 μm or less, so that the laser light transmission is excellent, so in the stealth dicing step, Excellent work division by stealth dicing.

6). Other Embodiments of Dicing Sheet FIG. 3 is a cross-sectional view of a dicing sheet according to another embodiment of the present invention. As shown in FIG. 3, the dicing sheet 1 </ b> A according to this embodiment includes a base material 2, a pressure-sensitive adhesive layer 3 laminated on one surface side (the upper side in FIG. 1), and a pressure-sensitive adhesive layer. 3 includes a jig pressure-sensitive adhesive layer 5 laminated on the peripheral edge opposite to the substrate 2, and a release sheet 6 laminated on the pressure-sensitive adhesive layer 3 and the jig pressure-sensitive adhesive layer 5. Is done. The adhesive layer 5 for jigs is a layer for bonding the dicing sheet 1 to a jig such as a ring frame. The release sheet 6 protects the pressure-sensitive adhesive layer 3 and the jig pressure-sensitive adhesive layer 5 until the dicing sheet 1A is used. That is, the dicing sheet 1A shown in FIG. 3 is obtained by adding the jig adhesive layer 5 to the dicing sheet 1 shown in FIG.

As an adhesive which comprises the adhesive layer 5 for jig | tool, what has desired adhesive force and removability is preferable, for example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a urethane adhesive Polyester-based pressure-sensitive adhesives, polyvinyl ether-based pressure-sensitive adhesives, and the like can be used. Among these, the adhesive layer 5 for jigs has high adhesiveness with jigs such as a ring frame, and can effectively prevent the dicing sheet 1A from being peeled off from the ring frame or the like in a dicing process or the like. It is preferable to use an acrylic adhesive. In addition, the base material as a core material may interpose inside the thickness direction of the adhesive layer 5 for jig | tool. Moreover, the base material may exist in the adhesive layer 3 side of the adhesive layer 5 for jig | tool.

The thickness of the pressure-sensitive adhesive layer 5 for jigs is preferably 5 to 200 μm, particularly preferably 10 to 100 μm, from the viewpoint of adhesion to a jig such as a ring frame.

In the dicing sheet 1A according to the present embodiment, the material and thickness of each member other than the jig adhesive layer 5 are the same as the material and thickness of each member of the dicing sheet 1 described above.

As an example of manufacturing the dicing sheet 1A, first, a pressure-sensitive adhesive that constitutes the pressure-sensitive adhesive layer 3 and, if desired, a pressure-sensitive adhesive layer-containing coating agent are applied to the release surface of the release sheet. The pressure-sensitive adhesive layer 3 is formed by drying. Then, the base material 2 is crimped | bonded to the exposed surface of the adhesive layer 3, and the laminated body which consists of the base material 2, the adhesive layer 3, and a peeling sheet is obtained.

Here, when the pressure-sensitive adhesive layer 3 is made of an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive layer 3 may be irradiated with energy rays at this stage to cure the pressure-sensitive adhesive layer 3. When laminating these layers, the pressure-sensitive adhesive layer 3 may be cured after laminating with other layers. When the pressure-sensitive adhesive layer 3 is cured after being laminated with another layer, the pressure-sensitive adhesive layer 3 may be cured before the dicing step, or the pressure-sensitive adhesive layer 3 may be cured after the dicing step.

As energy rays, ultraviolet rays, electron beams, etc. are usually used. Irradiation of energy rays varies depending on the kind of energy rays, for example, in the case of ultraviolet rays, preferably 50 ~ 1000mJ / cm ² in quantity, especially 100 ~ 500mJ / cm ² preferably. In the case of an electron beam, about 10 to 1000 krad is preferable.

The laminate of the base material 2 and the pressure-sensitive adhesive layer 3 may be half-cut if desired, and formed into a desired shape, for example, a shape corresponding to a workpiece (semiconductor wafer). In this case, an excess portion generated by the half cut may be removed as appropriate.

Next, the release sheet is peeled off from the pressure-sensitive adhesive layer 3, and a jig pressure-sensitive adhesive layer 5 is formed on the exposed peripheral edge of the pressure-sensitive adhesive layer 3. The jig pressure-sensitive adhesive layer 5 can also be formed by coating in the same manner as the pressure-sensitive adhesive layer 3. Finally, a release sheet 6 is laminated on the exposed surfaces of the pressure-sensitive adhesive layer 3 and the jig pressure-sensitive adhesive layer 5 to obtain a dicing sheet 1A.

As mentioned above, although one manufacturing method of dicing sheet 1A was shown, it is not limited to this. For example, when the jig pressure-sensitive adhesive layer 5 has a base material, after forming a laminate constituting the jig pressure-sensitive adhesive layer 5 on the release sheet, an annular shape corresponding to the jig, etc. It is also possible to make a half cut into the shape and laminate the adhesive layer 3 on the adhesive layer 3.

The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, another layer may be interposed between the base material 2 and the pressure-sensitive adhesive layer 3 in the dicing sheets 1 and 1A. Further, another layer may be interposed between the adhesive layer 3 and the release sheet 6 in the dicing sheets 1 and 1A. Examples of the other layer include a die bonding film. In this case, the dicing sheets 1 and 1A can be used as a dicing die bonding sheet.

In the composite sheet for forming a protective film according to the present invention, the arithmetic average roughness (Ra1) before heating on the back surface of the substrate 2 is about 0.51 to 0.65 μm and heated at 130 ° C. for 2 hours. In addition to setting the arithmetic average roughness (Ra2) of about 0.08 to 0.22, the storage elastic modulus of the base material 2 at 130 ° C. is set to about 13 to 20 MPa. It will be excellent.

Hereinafter, the present invention will be described more specifically with reference to examples and the like, but the scope of the present invention is not limited to these examples and the like.

[Example 1]
In Example 1, a dicing sheet 1 as shown in FIGS. 1 and 4 was manufactured as follows.

(1) Production of Laminate The following components (A) and (B) were mixed and diluted with methyl ethyl ketone so that the solid content concentration was 30% by mass to prepare an adhesive layer coating agent.
(A) Adhesive main agent: (meth) acrylic acid ester copolymer (copolymer obtained by copolymerizing 40 parts by mass of butyl acrylate, 55 parts by mass of 2-ethylhexyl acrylate, and 5 parts by mass of 2-hydroxylethyl acrylate) , Weight average molecular weight: 600,000) 100 parts by mass (B) Crosslinker: aromatic polyisocyanate compound (Mitsui Chemicals, Takenate D110N) 10 parts by mass

Next, arithmetic average roughness (Ra1) before heating of one surface (back surface of the base material: corresponding to the second surface of the base material), and arithmetic average roughness after heating (130 ° C., 2 hours) (Ra2), an ethylene-propylene copolymer film having a melting point and a storage elastic modulus at 130 ° C. adjusted as shown in Table 1 below, and subjecting the other side of the film to corona treatment, did. In addition, the arithmetic mean roughness (Ra1) before the heating was adjusted by changing the arithmetic surface roughness of the surface of the metal roll on which the back side was wound up when the substrate was formed. The arithmetic average roughness (Ra2) after the heating was adjusted by changing the copolymerization ratio of ethylene and propylene constituting the ethylene-propylene copolymer of the base material.

Prepare a release sheet (SP-PET 381031 manufactured by Lintec Co., Ltd.) with a silicone release agent layer formed on one side of a 38 μm thick PET film, and use the adhesive layer on the release surface of the release sheet. The coating agent was applied with a knife coater so that the finally obtained pressure-sensitive adhesive layer had a thickness of 10 μm, and dried to form a pressure-sensitive adhesive layer. Thereafter, the above-mentioned corona-treated surface of the base material is laminated on the pressure-sensitive adhesive layer and bonded together, and the base material (base material 2 in FIG. 1), the pressure-sensitive adhesive layer (pressure-sensitive adhesive layer 3 in FIG. 1), the release sheet, A laminate comprising: This laminated body was long, wound up in a roll shape to obtain a rolled body, and then cut into a width direction of 300 mm (indicated by w ₁ in FIG. 4).

(2) Production of dicing sheet The laminate obtained in the above (1) was half-cut so as to cut the laminate of the substrate and the pressure-sensitive adhesive layer from the substrate side. Specifically, as shown in FIG. 4, a circular shape (diameter d ₁ : 270 mm; reference numeral 401 in FIG. 4; circular dicing sheet body) is formed, and an interval of 20 mm from the circular shape to the outside (in FIG. 4). , Indicated by w ₂ ) was formed (reference numeral 402 in FIG. 4). In addition, two straight lines (reference numeral 403 in FIG. 4) parallel to the end portions in the width direction of the stacked body were formed between the adjacent circles, and the adjacent arcs were connected by the straight lines.

Thereafter, the part between the circular dicing sheet main body and the arc and the part sandwiched between the two straight lines were removed, and the dicing sheet shown in FIGS.

[Examples 2 to 5 and Comparative Examples 1 to 3]
The arithmetic average roughness (Ra1) before heating and the arithmetic average roughness (Ra2) after heating, the melting point and the storage elastic modulus at 130 ° C. on the back surface of the base material were changed as shown in Table 1 below. In the same manner as in Example 1, dicing sheets of Examples 2 to 5 and Comparative Examples 1 to 3 were produced.

[Test Example 1] <Measurement of arithmetic average roughness of substrate>
The arithmetic average roughness before heating (Ra1: μm) and the arithmetic average roughness after heating (Ra2: μm) on the back surface of the base material used in Examples and Comparative Examples were measured using a contact-type surface roughness meter (manufactured by Mitutoyo Corporation). , SURFTEST SV-3000), the cut-off value λc was 0.8 mm, the evaluation length Ln was 4 mm, and the measurement was performed according to JIS B0601: 2001. The results are shown in Table 1 below.

Here, for the arithmetic average roughness (Ra2) after heating, the dicing sheets of the examples and comparative examples provided with the base material were fixed to a ring frame, and in an oven at 130 ° C. in an air atmosphere. After heating for 2 hours, the value after standing to cool to room temperature was measured. During the heat treatment, the measurement surface (the back surface of the base material) was not in contact with the inner wall or bottom of the oven.

[Test Example 2] <Measurement of melting point of substrate>
About the base material used by the Example and the comparative example, melting | dissolving peak temperature was calculated | required based on JISK7121 (ISO3146) using the differential scanning calorimeter (TA Instruments company make, Q2000). Specifically, the substrate was heated from 23 ° C. to 200 ° C. at 10 ° C. per minute to draw a DSC curve. The melting peak temperature (° C.) was determined from the obtained DSC curve at the time of temperature increase. The results are shown in Table 1 below.

[Test Example 3] <Measurement of storage elastic modulus of substrate>
With respect to the base materials used in Examples and Comparative Examples, the storage elastic modulus at 130 ° C. was measured with the following apparatus and conditions. The results are shown in Table 1 below.
Measuring device: Dynamic instrument measurement device “DMA Q800” manufactured by TA Instruments
Test start temperature: 0 ° C
Test end temperature: 200 ° C
Temperature increase rate: 3 ° C / min Frequency: 11Hz
Amplitude: 20 μm

[Test Example 4] <Measurement of light transmittance>
As shown in Test Example 1, the base materials used in the examples and comparative examples were heated at 130 ° C. for 2 hours, and then the heated base materials were subjected to UV-visible spectrophotometer (manufactured by Shimadzu Corporation, UV- 3101PC (without integrating sphere)), the light transmittance at a wavelength of 200 to 1200 nm was measured, and the measured value at a wavelength of 1064 nm was read. The results are shown in Table 1 below.

[Test Example 5] <Evaluation of blocking resistance>
The dicing sheets produced in the examples and comparative examples were set in a sticking apparatus (RAD-2700 F / 12, manufactured by Lintec Corporation), and roll-to-roll in a 70 ° C. environment at a silicon wafer (outer diameter: The dicing sheet main body was affixed to 8 inches, thickness: 100 μm) and a ring frame (made of stainless steel). At that time, 10 sheets were continuously applied, and blocking resistance was evaluated based on the following criteria. The results are shown in Table 1 below.
A: It was possible to apply without any problem (no blocking occurred at all).
B: Although pasting was possible, a part of the base material and the release sheet on the back side of the base material were in close contact, and the release sheet was partly released from the adhesive layer when the dicing sheet was fed out.
C: Even with one sheet, the dicing sheet main body was transferred to the release sheet on the back side of the base material, or a sticking failure such that the dicing sheet could not be fed out occurred (blocking occurred).

[Test Example 6] <Dicing division property evaluation>
The dicing sheets produced in the examples and comparative examples were set in a sticking apparatus (RAD-2700 F / 12, manufactured by Lintec Corporation), and the silicon wafer (outer diameter: 8 inches, thickness: 100 μm) in an environment of 70 ° C. ) And a ring frame (made of stainless steel). Thereafter, heat treatment was performed at 130 ° C. for 2 hours.

Next, the silicon wafer on the dicing sheet was subjected to division processing by stealth dicing consisting of the following steps using a laser saw (DFL 7360, manufactured by Disco Corporation).
(Step 1) The silicon wafer and the ring frame to which the dicing sheets of Examples and Comparative Examples are attached are placed at predetermined positions of the laser saw so that laser light can be irradiated from the back side of the substrate.
(Step 2) After detecting the position of the surface of the silicon wafer, the focal position of the laser beam of the laser saw is set, and the planned cutting line is set so that a 9 mm × 9 mm chip body is formed on the silicon wafer. Then, a laser beam having a wavelength of 1064 nm is irradiated from the laser saw 10 times from the back side of the substrate to form a modified layer in the silicon wafer.
(Step 3) The silicon wafer and the ring frame to which the dicing sheet is attached are placed on a die separator (DDS 2300, manufactured by Disco Corporation), and expanded at a pulling rate of 100 mm / second and an expanding amount of 10 mm.

Through the above-described steps, at least a part of the silicon wafer having the modified layer formed therein was divided along the line to be divided, and a plurality of chips were obtained. Based on the division ratio (= (number of chips actually obtained / number of chips planned to be divided) × 100) (%), the dicing division property was evaluated according to the following criteria. The results are shown in Table 1 below.
A: Chip division ratio 100% (excellent division)
B: Chip division ratio of 90% or more and less than 100% (having an acceptable division property)
C: Chip division rate of 80% or more and less than 90% (having an acceptable division property)
D: Chip division rate of less than 80% (does not have acceptable division)

As can be seen from Table 1, the arithmetic average roughness (Ra1) before heating on the back surface of the substrate is 0.2 μm or more, and the arithmetic average roughness (Ra2) after heating at 130 ° C. for 2 hours on the back surface of the substrate. ) Is 0.25 μm or less, the dicing sheet of the example was excellent in blocking resistance and also in dicing resolution.

The dicing sheet according to the present invention is suitably used when it includes a step of irradiating a laser beam so as to transmit the substrate, such as stealth dicing.

DESCRIPTION OF SYMBOLS 1,1A ... Dicing sheet 2 ... Base material 3 ... Adhesive layer 401 ... Circular 402 ... Arc 403 ... Straight line 5 ... Jig adhesive layer 6 ... Release sheet 7 ... Semiconductor wafer 8 ... Ring frame

Claims (7)

A substrate;
A pressure-sensitive adhesive layer laminated on the first surface side of the substrate;
A dicing sheet provided with a release sheet laminated on the side of the pressure-sensitive adhesive layer opposite to the base material,
The arithmetic average roughness (Ra1) on the second surface of the substrate is 0.2 μm or more,
The arithmetic average roughness (Ra2) of the second surface of the substrate after heating the dicing sheet at 130 ° C. for 2 hours is 0.25 μm or less. The dicing sheet according to claim 1, wherein the arithmetic average roughness (Ra2) after the heating on the second surface of the substrate is smaller than the arithmetic average roughness (Ra1). The dicing sheet according to claim 1 or 2, wherein the base material has a melting point of 90 to 180 ° C. The dicing sheet according to any one of claims 1 to 3, wherein the substrate has a storage elastic modulus at 130 ° C of 1 to 100 MPa. The dicing sheet according to any one of claims 1 to 4, wherein the substrate has a light transmittance of 40% or more at a wavelength of 1064 nm after the heating. The dicing sheet according to any one of claims 1 to 5, wherein the base material is a film composed of a copolymer of ethylene and propylene. The dicing sheet includes a jig pressure-sensitive adhesive layer laminated on a peripheral edge of the pressure-sensitive adhesive layer opposite to the base material side. The dicing sheet described.

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