TWI759345B - Adhesive sheet for stealth dicing and manufacturing method of semiconductor device - Google Patents

Abstract

The present invention provides an adhesive sheet for stealth dicing, which is an adhesive sheet for stealth dicing comprising a base material and an adhesive layer laminated on one side of the base material, and the base material has a tensile modulus of elasticity at 23° C. 50 MPa or more and 450 MPa or less, the adhesive layer is composed of an energy ray-curable adhesive containing an acrylic copolymer, wherein the acrylic copolymer contains n-butyl acrylate, 2-hydroxyethyl acrylate, and carbon of an alkyl group The number of alkyl (meth)acrylates is 2 or less as a constituent monomer. The adhesive sheet for stealth dicing is excellent in solvent resistance and thermal shrinkage.

Description

Adhesive sheet for stealth dicing and manufacturing method of semiconductor device

The present invention relates to an adhesive sheet for stealth dicing (registered trademark), preferably an adhesive sheet for stealth dicing that uses a semiconductor wafer having a through electrode as a processing object.

In response to the increase in capacity and high functionality of electronic circuits, the development of multilayer circuits in which a plurality of semiconductor chips are stacked three-dimensionally is in progress. In such a multilayer circuit, the conductive connection of semiconductor wafers has been conventionally performed by wire bonding. The semiconductor wafer is provided with electrodes (TSV) penetrating from the circuit formation surface to the back surface, and the method of electrically connecting the wafers located directly above and below is an effective method. As a method of manufacturing a wafer with through electrodes, for example, a through hole is formed in a predetermined position of a semiconductor wafer by plasma or the like, and a conductor such as copper is poured into the through hole, and then etching or the like is performed to form a through hole in the semiconductor wafer. The method of providing circuits and through electrodes on the surface of the circle, etc. At this point, the wafer will be heated.

Such ultra-thin wafers and TSV wafers are easily broken, so they may be broken during a back grinding step, a subsequent processing step, and a transport step. Therefore, in these steps, the wafer is held on a rigid support such as glass through an adhesive. As this adhesive, a general-purpose adhesive such as acrylic, epoxy, and inorganic may be used. In addition, when the wafer is exposed to high temperature during the processing, the wafer and the rigid support are bonded with a high heat-resistant adhesive, such as a polyimide-based adhesive.

After the back-grinding and processing of the wafer is completed, the wafer is transferred from the hard support to the dicing plate, and the peripheral portion of the dicing plate is fixed with a ring frame, and the wafer is divided into chips by circuit units. The wafer is then picked up from the dicing sheet. When the wafer is transferred from the rigid support to the dicing plate, the wafer-side surface of the rigid support to which the wafer is fixed is attached to the dicing plate, the rigid support is peeled off from the wafer, and the wafer is removed. The circle is transferred to the cutting board. When the hard support is peeled off, the adhesive is softened by heating to perform thermal sliding to make the hard support slide; or the adhesive is decomposed by laser light irradiation to peel off the hard support. However, there may be cases where adhesive or its decomposition products remain attached to the wafer surface after the hard support has been peeled off.

In order to clean and remove the remaining adhesive residue, the wafer fixed on the dicing board is sometimes cleaned with an organic solvent. For this cleaning, for example, the laminate of the dicing plate and the wafer is immersed in an organic solvent; or a frame slightly larger than the wafer is arranged around the wafer, and an organic solvent is poured into the frame to clean the wafer . When peeling the wafer from the hard support, in addition to the above method, the wafer and the hard support are also immersed in an organic solvent.

During the above cleaning, the adhesive layer of the dicing board will swell or dissolve due to the organic solvent, and the adhesive force will be lost, and sometimes the wafer and the ring frame will fall off from the dicing board. In addition, since the substrate of the dicing sheet is wrinkled due to the organic solvent, when it is attached to a thin wafer like a TSV wafer, there is a problem that the wafer is broken.

One of the problems of Patent Document 1 is that the adhesive will not dissolve and contaminate the semiconductor element even if it comes into contact with a cleaning solution. It discloses an adhesive tape for semiconductor processing, which includes a base resin film, and a predetermined proportion of silicon Adhesive layer of acrylate or fluoro oligomer.

Moreover, the subject of Patent Document 2 is to provide an adhesive sheet for processing electronic parts which can maintain the adhesive force of the adhesive layer even if it comes into contact with an organic solvent, and has no wrinkles on the substrate and is excellent in chip pick-up properties, and discloses an electronic component. An adhesive sheet for parts processing, comprising: a base material containing polybutylene terephthalate, and an adhesive layer containing a predetermined energy ray-curable polymer.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5607847

[Patent Document 2] Japanese Patent Laid-Open No. 2015-72997

When the semiconductor wafer obtained by the above-mentioned dicing is picked up, a step of expanding the adhesive sheet to which the semiconductor wafer is attached is performed. Thereby, the semiconductor wafers are separated from each other, and the semiconductor wafers are easily picked up. Such an expansion is carried out by supporting the area of the adhesive sheet with the semiconductor chip from the opposite side to the surface where the semiconductor chip is attached, so that the annular frame attached to the peripheral edge of the adhesive sheet is formed. The height is lower relative to the height of the pedestal.

In addition, when the above-mentioned expansion is performed, after the dicing plate is adsorbed by the suction table while maintaining the expanded state, the region between the region to which the annular frame is attached and the region to which the semiconductor wafer is attached in the dicing plate may be implemented. A process of heating and shrinking it (heat shrink). Since the shrinkage generates a force in the dicing plate to expand the region where the semiconductor wafer is attached in the direction of the peripheral portion, as a result, even after the dicing plate is released from the suction by the suction table, the semiconductor wafers can be kept separated from each other. state.

However, among the dicing methods, there are a dicing method using a dicing blade, a dicing method (stealth dicing) in which a modified portion is formed by irradiation with laser light and divided in the modified portion when expanded. Among them, in the method using the dicing blade, since the portion of the semiconductor wafer that the dicing blade contacts is cut, the obtained semiconductor wafers are separated by the cut width component even if they are not expanded. On the other hand, in the case of stealth dicing, a modified portion is formed in the semiconductor wafer by irradiation of laser light, and the semiconductor wafer is divided into a plurality of wafers in the modified portion. Therefore, the portion cut as described above does not appear in the semiconductor wafer, and most of the obtained semiconductor wafers are in contact with each other without spreading.

Therefore, when performing the aforementioned heat shrinking, it is more difficult to maintain a state in which the wafers are separated from each other by a large distance in the stealth dicing than in the dicing using a dicing blade, and problems such as poor pickup are likely to occur.

Therefore, the adhesive sheet used in the aforementioned cleaning with an organic solvent and also used in stealth dicing is particularly required to have solvent resistance, and at the same time, the adhesive sheet can be satisfactorily shrunk due to thermal shrinkage, and the semiconductor wafer can be maintained. A state in which they are well separated from each other (hereinafter sometimes referred to as "good heat shrinkability").

However, as in the adhesive tape for semiconductor wafer processing disclosed in Patent Document 1, the adhesive layer exhibits predetermined solvent resistance, but a material that cannot exhibit sufficient solvent resistance is used as the base material. Therefore, in the cleaning step, the base material is When exposed to a solvent, there is a problem that the adhesive tape for semiconductor processing is wrinkled and the semiconductor wafer is broken.

In addition, the adhesive sheet for processing electronic parts disclosed in Patent Document 2 uses a polybutylene terephthalate film that is not easily shrunk by heating as a base material, and therefore, it is difficult to maintain good quality between semiconductor wafers by thermal shrinkage. state of separation.

In view of this situation, the present invention aims to provide an adhesive sheet for stealth dicing excellent in solvent resistance and thermal shrinkage.

In order to achieve the above object, the first aspect of the present invention provides an adhesive sheet for stealth dicing (Invention 1), which is an adhesive sheet for stealth dicing comprising a base material and an adhesive layer laminated on one side of the base material, It is characterized in that: the tensile modulus of elasticity of the substrate at 23°C is above 50 MPa and below 450 MPa, and the adhesive layer is composed of an energy ray-curable adhesive containing an acrylic copolymer, wherein the acrylic copolymer contains acrylic acid positive. Butyl ester, 2-hydroxyethyl acrylate, and alkyl (meth)acrylate having 2 or less carbon atoms in the alkyl group are used as constituent monomers.

The adhesive sheet for stealth dicing of the above invention (Invention 1) is excellent in thermal shrinkage because the tensile modulus of elasticity at 23° C. of the base material is in the above range. In addition, since the adhesive layer is composed of the above-mentioned energy ray-curable adhesive, excellent solvent resistance is exhibited. By laminating such an adhesive on one side of the substrate, even if the solvent comes into contact with the adhesive layer side of the adhesive sheet for stealth dicing, the adhesive layer can still be used to block the contact between the substrate and the solvent. , it is possible to suppress the occurrence of wrinkles in the base material and the cracking of the workpiece caused by this.

In the above invention (Invention 1), it is preferable that the content of the 2-hydroxyethyl acrylate in all monomers constituting the main chain of the acrylic copolymer is 5 mass % or more and 40 mass % or less, which constitutes the acrylic copolymer. Content of the alkyl (meth)acrylate whose carbon number of the alkyl group is 2 or less is 5 mass % or more and 40 mass % or less in all the monomers of the main chain of a copolymer (Invention 2).

In the above-mentioned inventions (Inventions 1 and 2), it is preferable that the content of the alkyl (meth)acrylate having a carbon number of 2 or less in the alkyl group in all the monomers constituting the main chain of the acrylic copolymer is relative to the content of the alkyl (meth)acrylate. Alkyl (meth)acrylate in which the content of n-butyl acrylate is 0.08 or more and 1.0 or less, and in all monomers constituting the main chain of the acrylic copolymer, the carbon number of the alkyl group is 2 or less The mass ratio of the content to the content of the 2-hydroxyethyl acrylate is 0.3 or more and 4.0 or less (Invention 3).

In the above inventions (Inventions 1 to 3), it is preferable that the glass transition temperature (Tg) of the acrylic copolymer is -50°C or higher and 0°C or lower (Invention 4)

In the above inventions (Inventions 1 to 4), it is preferable that the dissolution parameter (SP value) of the acrylic copolymer is 9.06 or more and 10 or less (Invention 5).

In the above inventions (Inventions 1 to 5), it is preferable that the alkyl (meth)acrylate having a carbon number of 2 or less in the alkyl group is methyl methacrylate, methyl acrylate or ethyl acrylate (Invention 6).

In the above inventions (Inventions 1 to 6), preferably the base material is selected from the group consisting of random polypropylene, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and ethylene-(meth)acrylic acid At least one of the copolymers is formed (Invention 7).

In the above inventions (Inventions 1 to 7), it is preferable to use a semiconductor wafer having a through electrode as a processing object (Invention 8).

In the above inventions (Inventions 1 to 8), it is preferably used in a method of manufacturing a semiconductor device including a step of cleaning the object to be processed laminated on the adhesive sheet for stealth dicing with a solvent (Invention 9).

In the above-mentioned inventions (Inventions 1 to 9), it is preferable to use a semiconductor device having a step of shrinking by heating a region of the adhesive sheet for stealth dicing on which the object is laminated, where the object is not laminated. In the production method (Invention 10).

The adhesive sheet for stealth dicing of the present invention is excellent in solvent resistance and thermal shrinkage.

Embodiments of the present invention will be described below.

The adhesive sheet for stealth dicing of the present invention includes a base material and an adhesive layer laminated on one side of the base material.

In the adhesive sheet for stealth dicing of the present embodiment, the tensile modulus of elasticity of the base material at 23° C. is 50 MPa or more and 450 MPa or less. The base material shrinks well when heated, so the adhesive sheet for stealth dicing provided with the base material has excellent thermal shrinkage.

In addition, in the adhesive sheet for stealth dicing of the present embodiment, the adhesive layer is composed of an energy ray-curable adhesive containing an acrylic copolymer, wherein the acrylic copolymer contains n-butyl acrylate, 2-hydroxyethyl acrylate , and an alkyl (meth)acrylate having 2 or less carbon atoms in the alkyl group as a constituent monomer. The adhesive exhibits excellent solvent resistance, so when the adhesive layer comes into contact with an organic solvent, the components in the adhesive layer can be prevented from being eluted into the organic solvent to contaminate the object to be processed, and the adhesive sheet for stealth dicing can be inhibited from affecting the object to be processed. The adhesion of the material decreases.

In addition, by laminating the above-mentioned solvent-resistant adhesive layer on one side of the substrate, when the organic solvent contacts the adhesive layer side in the adhesive sheet for stealth dicing, the adhesive layer can be used to block the contact of the organic solvent. As a result, the base material can be prevented from wrinkling due to contact with an organic solvent, and as a result, cracks of the object to be processed attached to the adhesive sheet for stealth dicing can be suppressed.

Moreover, as a process object using the adhesive sheet for stealth dicing of this embodiment, for example, semiconductor members, such as a semiconductor wafer and a semiconductor package, glass members, such as a glass plate, are mentioned. The above-mentioned semiconductor wafer may also be a semiconductor wafer with through electrodes (TSV wafer). The adhesive sheet for stealth dicing of the present embodiment can suppress the occurrence of wrinkles due to contact with an organic solvent as described above, so even if the thickness of the object to be processed is thin, the cracking of the object to be processed can be suppressed. Therefore, generally, a semiconductor wafer having a through-electrode having a very thin thickness is suitable as an object to be processed for use as an adhesive sheet for stealth dicing.

1. Components of the adhesive sheet for stealth cutting

(1) Substrate

In the adhesive sheet for stealth dicing of the present embodiment, the tensile modulus of elasticity of the base material at 23° C. is 450 MPa or less, preferably 400 MPa or less, especially 300 MPa or less. Moreover, the tensile elastic modulus is preferably 50 MPa or more, preferably 70 MPa or more, and particularly preferably 100 MPa or more. If the tensile elasticity coefficient exceeds 450 MPa, the substrate cannot be sufficiently shrunk even if heated. Therefore, after thermal shrinkage, when the semiconductor wafer and glass wafer are adsorbed and released from the adhesive sheet for stealth dicing from the adsorption stage, the semiconductor The wafer and the glass wafer cannot be maintained in a sufficiently separated state. On the other hand, if the tensile elastic modulus is less than 50 MPa, the base material cannot have sufficient rigidity, and the workability and handleability of the adhesive sheet for stealth dicing are lowered. In addition, the details of the measuring method of this tensile elastic modulus are as described in the later-mentioned test example.

As the material of the base material, as long as it can exhibit the above-mentioned tensile elasticity coefficient, and can exhibit a desired function in the use step of the adhesive sheet for stealth dicing, it is preferably capable of being irradiated with energy rays for curing the adhesive layer. Good penetrability is exerted, and there are no special restrictions. For example, the substrate is preferably a resin film mainly composed of a resin-based material, and specific examples thereof include polyethylene films, polypropylene films, polybutene films, polybutadiene films, and polymethylpentene. Polyolefin-based films such as films, ethylene-norbornene copolymer films, norbornene resin films; ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)acrylate copolymer films, other ethylene- (Meth)acrylate copolymer film etc. vinyl copolymer film; ethylene vinyl acetate copolymer film; polyvinyl chloride film, vinyl chloride copolymer film etc. polyvinyl chloride film; (meth)acrylate Copolymer film; polyurethane film; polystyrene film; fluororesin film, etc. In the polyolefin-based film, the polyolefin may be a block copolymer or a random copolymer. As an example of a polyethylene film, a low density polyethylene (LDPE) film, a linear low density polyethylene (LLDPE) film, a high density polyethylene (HDPE) film, etc. are mentioned. In addition, modified films such as their cross-linked films and ionomer films can also be used. In addition, the base material may be a laminated film obtained by laminating several layers of the above-mentioned films. In this laminated film, the materials constituting the respective layers may be the same or different. In addition, in this specification, "(meth)acrylic acid" means both acrylic acid and methacrylic acid. The same applies to other similar terms.

As the base material, among the above-mentioned films, from the viewpoint of easily exerting a tensile elastic modulus, a low-density polyethylene (LDPE) film, a linear low-density polyethylene (LLDPE) film, and a polypropylene film of a random copolymer are preferably used. (random polypropylene film) or ethylene-methacrylic acid copolymer film.

The base material may contain various additives such as flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, and ion trapping agents. The content of these additives is not particularly limited, but is preferably set within a range in which the substrate exhibits a desired function.

Surface treatments such as primer treatment, corona treatment, plasma treatment, etc. can also be performed on the surface of the substrate with the adhesive layer in order to improve the adhesiveness with the adhesive layer.

The thickness of the base material is preferably 450 μm or less, particularly 400 μm or less, and more preferably 350 μm or less. In addition, the thickness is preferably 20 μm or more, particularly 25 μm or more, and more preferably 50 μm or more. Since the thickness of the base material is 450 μm or less, the base material is easily thermally shrunk, and the semiconductor wafer and the glass wafer can be well separated and maintained. In addition, since the thickness of the base material is 20 μm or more, the base material has good rigidity, and the adhesive sheet for stealth dicing can effectively support the object to be processed.

(2) Adhesive layer

In the adhesive sheet for stealth dicing of the present embodiment, the adhesive layer is composed of an energy ray-curable adhesive containing an acrylic copolymer (hereinafter sometimes referred to as "acrylic copolymer (a1)"), wherein the acrylic The type copolymer contains n-butyl acrylate, 2-hydroxyethyl acrylate, and alkyl (meth)acrylate having 2 or less carbon atoms in the alkyl group as constituent monomers. Since the adhesive layer is composed of the above-mentioned adhesive, excellent solvent resistance is exhibited.

Examples of alkyl (meth)acrylates having an alkyl group containing 2 or less carbon atoms as a constituent monomer in the acrylic copolymer (a1) include methyl methacrylate, methyl acrylate, and methacrylic acid. ethyl ester and ethyl acrylate. Among them, from the viewpoint of exhibiting excellent solvent resistance, the alkyl (meth)acrylate whose alkyl group has 2 or less carbon atoms is preferably methyl methacrylate, methyl acrylate, or ethyl acrylate.

The acrylic copolymer (a1) may contain monomers other than n-butyl acrylate, 2-hydroxyethyl acrylate, and alkyl (meth)acrylate having 2 or less carbon atoms as constituent monomers. body.

For example, the acrylic copolymer (a1) may further contain functional group-containing monomers other than 2-hydroxyethyl acrylate as a constituent monomer. Such a functional group-containing monomer is preferably a monomer having a polymerizable double bond in the molecule and a functional group such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, and an epoxy group.

As a monomer containing a hydroxyl group in the molecule, for example, 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, (methyl) 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. may be used alone or in combination of two or more.

As a monomer containing a carboxyl group in a molecule|numerator, ethylenically unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid, is mentioned, for example. These can be used alone or in combination of two or more.

As a monomer containing an amino group in a molecule|numerator or a monomer containing a substituted amino group, for example, aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. are mentioned. These can be used alone or in combination of two or more.

In addition, the acrylic copolymer (a1) may contain an alkyl (meth)acrylate having 3 to 20 carbon atoms in an alkyl group other than n-butyl acrylate as a constituent monomer, and may have an alicyclic ring in the molecule. Monomer of formula structure (monomer containing alicyclic structure).

As an example of the alkyl (meth)acrylate having 3 to 20 carbon atoms, propyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like can be suitably used. These can be used alone or in combination of two or more.

As the alicyclic structure-containing monomer, for example, cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, adamantyl (meth)acrylate, and (meth)acrylic acid can be suitably used. Isobornate, dicyclopentenyl (meth)acrylate, cyclopentenyloxyethyl (meth)acrylate, etc. are preferable. These can be used alone or in combination of two or more.

In addition, the acrylic copolymer (a1) can also be used for n-butyl acrylate, 2-hydroxyethyl acrylate, alkyl (meth)acrylate having 2 or less carbon atoms in the alkyl group, and other monomers as needed. The formed main chain is bonded as a side chain compound. As an example of such a compound, the unsaturated group containing compound (a2) mentioned later is mentioned, for example.

Among all the monomers constituting the main chain of the acrylic copolymer (a1), the content of n-butyl acrylate is preferably 20% by mass or more. Moreover, it is preferable that this content is 85 mass % or less. By containing n-butyl acrylate in the main chain of the acrylic copolymer (a1) in the content of the above-mentioned range as a constituent monomer, the adhesive layer tends to exhibit excellent solvent resistance.

Among all the monomers constituting the main chain of the acrylic copolymer (a1), the content of 2-hydroxyethyl acrylate is preferably 5% by mass or more, particularly preferably 10% by mass or more. Moreover, it is preferable that this content is 40 mass % or less, and it is especially preferable that it is 30 mass % or less. By containing 2-hydroxyethyl acrylate in the main chain of the acrylic copolymer (a1) in the content of the above-mentioned range as a constituent monomer, the adhesive layer tends to exhibit excellent solvent resistance.

Among all the monomers constituting the main chain of the acrylic copolymer (a1), the content of the alkyl (meth)acrylate having an alkyl group with a carbon number of 2 or less is preferably 5% by mass or more, particularly 10% by mass or more better. Moreover, it is preferable that this content is 40 mass % or less, and it is especially preferable that it is 30 mass % or less. By containing an alkyl (meth)acrylate having an alkyl group with a carbon number of 2 or less in the main chain of the acrylic copolymer (a1) in the above-mentioned range as a constituent monomer, the adhesive layer tends to exhibit excellent resistance. Solvent.

In addition, in all the monomers constituting the main chain of the acrylic copolymer (a1), the mass ratio of the content of the alkyl (meth)acrylate having the carbon number of the alkyl group of 2 or less to the content of n-butyl acrylate was 0.08 More preferably, it is more preferably 0.1 or more. In addition, the mass ratio is preferably 1.0 or less, particularly 0.9 or less. When the mass ratio is within the above-mentioned range, the adhesive layer tends to exhibit excellent solvent resistance.

Among all the monomers constituting the main chain of the acrylic copolymer (a1), the mass ratio of the content of the alkyl (meth)acrylate having an alkyl group with a carbon number of 2 or less to the content of 2-hydroxyethyl acrylate is 0.3 More preferably, it is more preferably 0.4 or more. Moreover, it is preferable that this mass ratio is 4.0 or less, and it is especially preferable that it is 3.5 or less. When the mass ratio is within the above-mentioned range, the adhesive layer tends to exhibit excellent solvent resistance.

In the adhesive sheet for stealth dicing of the present embodiment, the glass transition temperature (Tg) of the acrylic copolymer (a1) is preferably -50°C or higher, particularly -48°C or higher. Moreover, it is preferable that the said glass transition temperature (Tg) is 0 degrees C or less, and it is especially preferable that it is -8 degrees C or less. When the glass transition temperature (Tg) is in the above-mentioned range, the adhesive layer tends to exhibit excellent solvent resistance. In addition, the details of the measuring method of the said glass transition temperature (Tg) are as described in the test example mentioned later.

In the adhesive sheet for stealth dicing of the present embodiment, the dissolution parameter (SP value) of the acrylic copolymer (a1) is 9.06 or more, and the above-mentioned dissolution parameter (SP value) is 10 or less. When the dissolution parameter (SP value) is in the above-mentioned range, the adhesive layer tends to exhibit excellent solvent resistance.

In the adhesive sheet for stealth dicing of the present embodiment, the adhesive layer is composed of an energy-ray-curable adhesive containing the above-mentioned acrylic copolymer (a1). Since the adhesive layer is made of an energy ray-curable adhesive, the adhesive layer can be hardened by irradiating the energy ray, and the adhesive force of the adhesive sheet for stealth dicing to the object to be processed can be reduced. Thereby, the semiconductor wafer obtained by stealth dicing can be easily picked up from the adhesive sheet for stealth dicing.

The energy-ray-curable adhesive constituting the adhesive layer may be a polymer with energy-ray-curability as the main component, or a non-energy-ray-curable polymer (polymer without energy-ray-curability) A mixture with at least one or more monomers and/or oligomers having an energy ray-curable group as the main component. Furthermore, it may be a mixture of a polymer having energy ray curability and a non-energy ray curable polymer, or may be a polymer having energy ray curability and at least one or more monomers having an energy ray curable group And/or a mixture of oligomers, a mixture of these three types may be used. Here, the aforementioned acrylic copolymer (a1) may be contained in the energy ray-curable adhesive in the form of a polymer having energy ray curability, or may be contained in the form of a polymer not having energy ray curability contain.

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

The polymer having energy ray curability is preferably a (co)polymer in which a functional group having energy ray curability (energy ray curable group) is introduced into the side chain of the aforementioned acrylic copolymer (a1). A) (hereinafter sometimes referred to as "energy ray-curable polymer (A)"). The energy ray-curable polymer (A) is preferably obtained by combining the aforementioned acrylic copolymer (a1) with a functional group (for example, derived from 2-hydroxyethyl acrylate) bonded to the acrylic copolymer (a1). It is obtained by reacting the unsaturated group-containing compound (a2) with the functional group of the hydroxyl group.

The energy ray-curable polymer (A) can be obtained by reacting the above-mentioned acrylic copolymer (a1) with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group.

The functional group possessed by the unsaturated group-containing compound (a2) can be appropriately selected according to the type of the functional group possessed by the acrylic copolymer (a1). The acrylic copolymer (a1) has a hydroxyl group derived from 2-hydroxyethyl acrylate, and when the hydroxyl group is used to react with the functional group possessed by the unsaturated group-containing compound (a2), it is used as the unsaturated group-containing compound (a2) The functional group possessed is preferably an isocyanate group or an epoxy group. In addition, when the acrylic copolymer (a1) has an amino group or a substituted amino group as a functional group, and they are used to react with the functional group possessed by the unsaturated group-containing compound (a2), the unsaturated group-containing compound (a2) ) has a functional group, preferably an isocyanate group or an epoxy group. In addition, when the acrylic copolymer (a1) has an epoxy group as a functional group, and is used to react with the functional group possessed by the unsaturated group-containing compound (a2), the unsaturated group-containing compound (a2) possesses As for the functional group, an amine group, a carboxyl group or an aziridinyl group is preferred.

Furthermore, in the above-mentioned unsaturated group-containing compound (a2), at least one, preferably 1 to 6, more preferably 1 to 4 energy ray polymerizable carbon-carbon double bonds are contained in one molecule . Specific examples of such an unsaturated group-containing compound (a2) include, for example, 2-methacryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, methyl Acryloyl isocyanate, allyl isocyanate, 1,1-(bisacrylooxymethyl)ethyl isocyanate; obtained by reaction of diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth)acrylate Acryloyl monoisocyanate compound; Acryloyl monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound, polyol compound, and hydroxyethyl (meth)acrylate; (meth)acrylic ring Oxypropyl ester; (meth)acrylic acid, (meth)acrylic acid 2-(1-aziridinyl)ethyl ester, 2-vinyl-2-oxazoline (2-vinyl-2-oxazoline), 2 -Isopropenyl-2-oxazoline (2-isopropenyl-2-oxazoline) and the like.

The above-mentioned unsaturated group-containing compound (a2) is preferably 50 mol % or more, particularly preferably 60 mol % or more, relative to the molar number of the functional group-containing monomer in the above-mentioned acrylic copolymer (a1). , and more preferably used in a proportion of 70 mol% or more. In addition, the above-mentioned unsaturated group-containing compound (a2) is preferably 95 mol % or less, particularly preferably 93 mol %, relative to the molar number of the functional group-containing monomer of the above-mentioned acrylic copolymer (a1). % or less, more preferably 90 mol% or less.

In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the difference between the functional group possessed by the acrylic copolymer (a1) and the functional group possessed by the unsaturated group-containing compound (a2) can be adjusted. The reaction temperature, pressure, solvent, time, presence or absence of a catalyst, and the type of catalyst are appropriately selected according to the combination. Thereby, the functional group present in the acrylic copolymer (a1) reacts with the functional group in the unsaturated group-containing compound (a2), and the unsaturated group is introduced into the side chain of the acrylic copolymer (a1) to obtain Energy ray curable polymer (A).

The weight average molecular weight (Mw) of the energy ray-curable polymer (A) obtained in this way is preferably 10,000 or more, particularly 150,000 or more, and further preferably 200,000 or more. In addition, the weight average molecular weight (Mw) is preferably 1.5 million or less, particularly preferably 1 million or less. In addition, the weight average molecular weight (Mw) in this specification is the conversion value of the standard polystyrene measured by gel permeation chromatography (GPC method).

Energy ray-curable adhesives, even when energy ray-curable polymers such as the energy ray-curable type (A) as the main component, the energy ray-curable adhesives may further contain energy ray-curable monomers and/or oligomer (B).

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

As the energy ray-curable monomer and/or oligomer (B), for example, monofunctional acrylates such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, trihydroxy acrylates, etc. can be used. trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate acrylate), dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate , Polyethylene glycol di(meth)acrylate, dimethylol tricyclodecane di(meth)acrylate, etc. acrylates, polyester oligo (meth) acrylate (oligo (meth) acrylate), polyurethane oligo (meth) acrylate (polyurethane oligo (meth) acrylate).

When the energy-ray-curable monomer and/or oligomer (B) is blended with the energy-ray-curable polymer (A), the energy-ray-curable monomer and/or oligomer (B) will The content in the radiation-curable adhesive is preferably more than 0 parts by mass, particularly preferably 60 parts by mass or more, relative to 100 parts by mass of the energy ray-curable polymer (A). Moreover, the content is preferably 250 parts by mass or less, particularly preferably 200 parts by mass or less, relative to 100 parts by mass of the energy ray-curable polymer (A).

Here, when ultraviolet rays are used as energy rays for curing the energy ray-curable adhesive, it is preferable to add a photopolymerization initiator (C). By using this photopolymerization initiator (C), the polymerization curing time can be reduced and light exposure.

Specific examples of the photopolymerization initiator (C) include benzoin, acetophenone, benzoin, benzoin methyl ether, and benzoin ethyl ether. ), benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin benzoate methyl, Benzoin dimethyl ketal (benzoin dimethyl ketal), 2,4-diethylthioxanthone (2,4-diethylthioxanthone), 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide (benzyl diphenyl sulfide) sulfide), tetramethylthiuram monosulfide, azobisisobutyronitrile, benzil, dibenzil, diacetyl (diacetyl), β-croll anthraquinone, (2,4,6-trimethylbenzyldiphenyl)phosphine oxide (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, 2- 2-benzothiazole-N,N-diethyl dithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propene base)phenyl]acetone}(oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}), 2,2-dimethoxy-1,2-diphenyl Ethane-1-one (2,2-Dimethoxy-1,2-diphenylethane-1-one) etc. These may be used alone or in combination of two or more.

The photopolymerization initiator (C) is an energy-ray-curable copolymer (when the energy-ray-curable monomer and/or oligomer (B) is blended with respect to the energy-ray-curable copolymer (A) ( The total amount of A) and the energy ray-curable monomer and/or oligomer (B) is 100 parts by mass) 100 parts by mass, preferably 0.1 part by mass or more, particularly preferably 0.5 part by mass or more. In addition, the photopolymerization initiator (C) is an energy ray-curable copolymer (when the energy ray-curable monomer and/or oligomer (B) is blended with respect to the energy-ray-curable copolymer (A) The total amount of the substance (A) and the energy ray-curable monomer and/or oligomer (B) is 100 parts by mass) 100 parts by mass, preferably 10 parts by mass or less, particularly preferably 6 parts by mass or less use.

In the energy ray-curable adhesive, other components may be appropriately blended in addition to the above-mentioned components. As other components, a non-energy-ray curable polymer component or oligomer component (D), a crosslinking agent (E), etc. are mentioned, for example.

Examples of the non-energy ray-curable polymer component or oligomer component (D) include polyacrylates, polyesters, polyurethanes, polycarbonates, polyolefins, etc. Preferably, the weight average molecular weight (Mw) is 30 million to 2.5 million polymers or oligomers. By blending this component (D) with the energy ray-curable adhesive, the adhesiveness and peelability before hardening, the strength after hardening, the adhesiveness with other layers, storage stability, and the like can be improved. The blending amount of the component (D) is not particularly limited, and can be appropriately determined within the range of more than 0 parts by mass and 50 parts by mass or less with respect to 100 parts by mass of the energy ray-curable copolymer (A).

As the crosslinking agent (E), a polyfunctional compound having reactivity with a functional group possessed by the energy ray-curable copolymer (A) and 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, oxazoles Oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, reactive phenolic resins, and the like.

The blending amount of the crosslinking agent (E) is preferably 0.01 part by mass or more, particularly preferably 0.03 part by mass or more, and more preferably 0.04 part by mass or more with respect to 100 parts by mass of the energy ray-curable copolymer (A). better. In addition, the blending amount of the crosslinking agent (E) is preferably 8 parts by mass or less, particularly preferably 5 parts by mass or less, and more preferably 3.5 parts by mass with respect to 100 parts by mass of the energy ray-curable copolymer (A). A portion or less is better.

Next, the following describes the case where the energy ray-curable adhesive is mainly composed of a mixture of a non-energy ray-curable polymer component and a monomer and/or oligomer having at least one energy ray-curable group .

As the non-energy-ray curable polymer component, the aforementioned acrylic copolymer (a1) can be used.

The weight average molecular weight (Mw) of the acrylic copolymer (a1) is preferably at least 100,000, particularly preferably at least 200,000. In addition, the weight average molecular weight (Mw) is preferably 1.3 million or less, particularly preferably 1 million or less.

As the monomer and/or oligomer having at least one or more energy ray-curable groups, those similar to those of the aforementioned component (B) can be selected. In terms of the blending ratio of the non-energy-ray-curable polymer component and the monomer and/or oligomer having at least one energy-ray-curable group, relative to the non-energy-ray-curable polymer component 100 The amount of monomers and/or oligomers having at least one energy ray-curable group is preferably 1 part by mass or more, particularly preferably 60 parts by mass or more, and the blending ratio is relative to the mass part. 100 parts by mass of non-energy ray-curable polymer components, preferably 200 parts by mass or less, especially 160 parts by mass or less of monomers and/or oligomers having at least one energy ray-curable group .

In this case, similarly to the above, the photopolymerization initiator (C) and the crosslinking agent (E) may be appropriately blended.

The thickness of the adhesive layer is preferably 1 μm or more, particularly 2 μm or more, and more preferably 3 μm or more. The thickness is preferably 50 m or less, particularly 30 m or less, and more preferably 20 m or less. When the thickness of the adhesive layer is 1 μm or more, the adhesive layer can be used to effectively block the organic solvent from contacting the substrate, and the substrate can be effectively prevented from wrinkling. Moreover, since the thickness of an adhesive bond layer is 50 micrometers or less, the adhesive force of the adhesive sheet for stealth dicing can be suppressed from becoming too high, and the occurrence of a pickup failure etc. can be suppressed effectively.

(3) Peel off the sheet

In the adhesive sheet for stealth dicing of the present embodiment, until the adhesive surface of the adhesive layer adheres to the object to be processed, in order to protect the surface, the sheet may be peeled off at the area layer. The composition of the peeling sheet is arbitrary, and a plastic film can be exemplified by peeling treatment with a peeling agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polypropylene, polyethylene, and the like. of polyolefin films. As the release agent, polysiloxane-based, fluorine-based, long-chain alkyl-based, etc. can be used, and among them, polysiloxane-based ones that are inexpensive and can obtain stable performance are preferred. The thickness of the peeling sheet is not particularly limited, but is usually 20 μm or more and 250 μm or less.

2. Manufacturing method of adhesive sheet for invisible dicing

In the adhesive sheet for stealth dicing of the present embodiment, the manufacturing method of the base material is not particularly limited as long as the base material can achieve the aforementioned tensile elastic coefficient and the adhesive layer is composed of the aforementioned energy ray-curable adhesive.

For example, an adhesive sheet for stealth dicing can be obtained by transferring the adhesive layer formed on the release sheet to one side of the base material. In this case, by preparing a coating solution containing an adhesive composition constituting an adhesive layer, and optionally a solvent or a dispersion medium, the peeling-treated side of the peeling sheet (hereinafter sometimes referred to as the On the "peeling surface"), use a die coater, curtain coater, sprayer, slot coater, knife coater, etc. to apply the coating liquid to form a coating film, and dry the coating film to form an adhesive layer. The properties of the coating liquid are not particularly limited as long as it can be applied, and the components for forming the adhesive layer may be contained as a solute or may be contained as a dispersoid. The peeling sheet in this layered product can be peeled off as a step material, and can also be used to protect the adhesive surface of the adhesive layer until the adhesive sheet for stealth dicing is attached to the object to be processed.

When the coating liquid used to form the adhesive layer contains a cross-linking agent, the above drying conditions (temperature, time, etc.) can be changed, or heat treatment can be performed separately, so that the energy ray hardening polymer ( A) or the crosslinking reaction of the non-energy ray-curable polymer component and the crosslinking agent (E) proceeds, and a crosslinked structure is formed at a desired density in the adhesive layer. In order to make this cross-linking reaction sufficiently proceed, after laminating the adhesive layer on the base material according to the above method, etc., the obtained adhesive sheet for stealth dicing can be carried out, for example, in a static environment of 23°C and a relative humidity of 50%. Let it mature for a few days.

Instead of transferring the adhesive layer formed on the release sheet to one side of the substrate as described above, the adhesive layer may be directly formed on the substrate. In this case, a coating film is formed by applying the coating liquid for forming the above-mentioned adhesive layer on one side of the substrate, and the coating film is dried to form an adhesive layer.

3. How to use the adhesive sheet for invisible cutting

The adhesive sheet for stealth dicing of this embodiment can be used for stealth dicing. Moreover, the adhesive sheet for stealth dicing of this embodiment can be used for the manufacturing method of the semiconductor device provided with the step of stealth dicing.

As described above, the adhesive sheet for stealth dicing of the present embodiment can be suitably used for a thin-thickness object because the cracking of the object can be suppressed. For example, the adhesive sheet for stealth dicing of the present embodiment can be suitably used for a semiconductor wafer (TSV) having through electrodes.

An example of the manufacturing method of the semiconductor device provided with the step of stealth dicing is demonstrated below. First, a step of backgrinding is performed on one side of the object to be processed (semiconductor wafer) fixed to the hard support. The semiconductor wafer is fixed to a rigid support, for example by means of an adhesive. As a rigid support, glass etc. can be used, for example. Back grinding can be carried out by a general method.

Then, the back-grinded semiconductor wafer is transferred from the hard support to an adhesive sheet for stealth dicing. At this time, after bonding the back-grinded surface of the semiconductor wafer and the surface on the adhesive layer side of the adhesive sheet for stealth dicing, the hard support is separated from the semiconductor wafer. The separation of the hard support from the semiconductor wafer can be carried out according to the method of the type of adhesive used to fix the hard support and the semiconductor wafer. The method of circular sliding; the method of decomposing the adhesive by laser irradiation, etc. In addition, after separating the semiconductor wafer from the rigid support, the peripheral portion of the adhesive sheet for stealth dicing is attached to the annular frame.

Then, a step of cleaning the semiconductor wafer laminated on the adhesive sheet for stealth dicing with a solvent is performed. Thereby, the adhesive agent remaining in the semiconductor wafer can be removed. The cleaning can be performed according to a general method, for example, a method of immersing a laminate of an adhesive sheet for stealth dicing and a semiconductor wafer in a solvent; a frame slightly larger than the semiconductor wafer is arranged to surround the wafer A method of injecting a solvent into a frame on an adhesive sheet for stealth dicing, etc. As the solvent, an organic solvent or the like can be used, and in particular, it is preferable to use an organic solvent from the viewpoint of effectively removing the adhesive. As a kind of organic solvent, p-menthane (p-menthane), d-limonene (d-limonene), 1,3,5- mesitylene (mesitylene) etc. can be used.

In the adhesive sheet for stealth dicing of the present embodiment, since the adhesive layer is composed of the aforementioned energy ray-curable adhesive, the adhesive layer exhibits excellent solvent resistance. Thereby, the components in the adhesive layer can be inhibited from being eluted into the organic solvent, the contamination of the semiconductor wafer caused by this can be inhibited, and the adhesive force of the adhesive sheet for stealth dicing to the semiconductor wafer can be inhibited from decreasing. In addition, since the adhesive with excellent solvent resistance is laminated on one side of the substrate, even if the solvent comes into contact with the adhesive layer side of the adhesive sheet for stealth dicing, the adhesive layer can still be used to block the substrate. contact with solvents. Thereby, it is possible to suppress the occurrence of wrinkles in the base material and the breakage of the semiconductor wafer or the like caused by this.

Then, if necessary, another semiconductor wafer may be laminated on the semiconductor wafer already laminated on the adhesive sheet for stealth dicing. At this time, the semiconductor wafers may be fixed to each other using an adhesive, for example, a non-conductive adhesive film (NCF) may be used. The stacking of semiconductor wafers can be repeated until the number of stacking layers becomes necessary. The lamination of such semiconductor wafers is particularly suitable when manufacturing a multilayer circuit using a TSV wafer as a semiconductor wafer.

Then, a semiconductor wafer or a laminate of semiconductor wafers (hereinafter referred to as "semiconductor wafer", unless otherwise specified, refers to a semiconductor wafer or a laminate of semiconductor wafers) is applied to the adhesive sheet for stealth dicing. Stealth cutting. In this step, the semiconductor wafer is irradiated with laser light to form a modified portion in the semiconductor wafer. Irradiation with laser light can be performed using equipment and conditions generally used in stealth dicing.

Then, the semiconductor wafer is divided in the modified portion formed by stealth dicing, and a plurality of semiconductor wafers are obtained. This division can be performed by, for example, setting the laminate of the adhesive sheet for stealth dicing and the semiconductor in a spreading device, and spreading it at 0° C. to room temperature.

Then, the adhesive sheet for stealth dicing is extended again. The main purpose of this extension is to separate the obtained semiconductor wafers from each other. The expanded state is further maintained, and the adhesive plate for stealth dicing is absorbed by the suction table. The expansion here can be carried out at room temperature or in a heated state. In addition, the expansion can be carried out by a general method using a general apparatus, and the suction stage used can also be carried out by using a general one.

Then, the adhesive sheet for stealth dicing is maintained to be sucked by the suction stage, and the area of the adhesive sheet for stealth dicing of the obtained laminated semiconductor wafer is shrunk by heating (thermal shrinkage). Specifically, the area between the area of the adhesive sheet for stealth dicing where the semiconductor wafer is laminated and the area where the annular frame is attached to the adhesive sheet for stealth dicing is heated to shrink the area. As a heating condition at this time, it is preferable that the temperature of the adhesive sheet for stealth dicing is 90 degreeC or more. Moreover, it is preferable that the temperature of the adhesive sheet for stealth dicing is 200 degrees C or less. The adhesive sheet for stealth dicing of the present embodiment is excellent in thermal shrinkage because the tensile modulus of elasticity of the base material at 23° C. is within the aforementioned range.

Then, the adhesive sheet for stealth dicing is released from the suction by the suction table. In the above-mentioned heat shrinking step, the area between the area where the semiconductor chip is laminated in the adhesive sheet for stealth dicing and the area where the ring-shaped frame is attached in the adhesive sheet for stealth dicing is shrunk. In the adhesive sheet for dicing, a force is generated that pulls the region to which the semiconductor wafer is attached toward the peripheral edge. As a result, even after the adhesive sheet for stealth dicing is released from suction by the suction stage, the semiconductor wafers can be kept separated from each other.

Then, each semiconductor wafer is picked up from the adhesive sheet for stealth dicing in the state separated from the adjacent semiconductor wafer. This pick-up can be performed in a conventional manner using conventional equipment. As described above, the adhesive sheet for stealth dicing of the present embodiment exhibits excellent thermal shrinkage properties, and as a result, the semiconductor wafers can be kept in a well-separated state, whereby pickup can be performed well.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-mentioned embodiment also includes all design changes and equivalents which belong to the technical scope of the present invention.

For example, another layer may be provided between the substrate and the adhesive layer, or on the surface of the substrate on the opposite side to the adhesive layer.

[Example]

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]

(1) Fabrication of base material

A resin composition containing two kinds of random copolymers of polypropylene in a ratio of 1:1 (manufactured by PRIMEPOLYMER, product name "PRIME TPO F-3740" 50 parts by mass and PRIMEPOLYMER company make, product name "PRIME TPO J- 5710 "50 parts by mass of the mixture) was extruded with a small T-die extruder (manufactured by Toyo Seiki Co., Ltd., product name "LABO PLASTOMILL") to obtain a substrate with a thickness of 70 μm.

(2) Preparation of adhesive composition

Acrylic copolymer (a1) obtained by reacting 50 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl acrylate (MA), and 30 parts by mass of 2-hydroxyethyl acrylate (HEA), with respect to The HEA of the acrylic copolymer (a1) was 80 mol % of methacryloyloxyethyl isocyanate (MOI) reacted to obtain an energy ray-curable polymer (A). This energy ray-curable polymer (A) was measured by the method described later, and the weight average molecular weight (Mw) was 500,000. Moreover, the solubility parameter (SP value) of the said acrylic copolymer (a1) was computed from the solubility parameter (SP value) of each monomer which comprises this acrylic copolymer (a1), and it was 9.61.

100 parts by mass of the obtained energy ray-curable polymer (in terms of solid content, the same below) and 1.0 part by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator and 1.0 part by mass of toluene diisocyanate (manufactured by Tosoh Corporation, product name "CORONATE L") as a crosslinking agent, mixed in a solvent to obtain an adhesive composition.

(3) Formation of the adhesive layer

For a release sheet (manufactured by LINTEC, product name "SP-PET381031") formed by forming a polysiloxane-based release agent layer on one side of a polyethylene terephthalate (PET) film with a thickness of 38 μm The said adhesive composition was apply|coated to the peeling surface, and it was made to dry by heating, and the adhesive layer with a thickness of 20 micrometers was formed on the peeling sheet.

(4) Production of adhesive sheet for invisible cutting

The surface of the adhesive layer formed in the above step (3) is on the opposite side to the peeling sheet, and the single side of the base material produced in the above step (1) is laminated to obtain an adhesive sheet for stealth dicing.

[Examples 2 to 5]

Except having changed the composition in the adhesive composition as shown in Table 1, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Example 6]

Using a resin composition containing ethylene-methacrylic acid copolymer (manufactured by Mitsui Dupont Polychemical Co., product name "NUCREL N0903HC"), a small T-die extruder (manufactured by Toyo Seiki Co., Ltd., product name "LABO PLASTOMILL") was used. ”), except that the base material having a thickness of 70 μm obtained by extrusion was carried out in the same manner as in Example 1 to produce an adhesive sheet for stealth dicing.

[Example 7]

Using a resin composition containing low density polyethylene (manufactured by Sumitomo Chemical Co., Ltd., product name "SUMIKATHENE F-412-1"), a small T-die extruder (manufactured by Toyo Seiki Co., Ltd., product name "LABO PLASTOMILL") Except for the base material of thickness 70 micrometers obtained by extrusion molding, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Example 8]

Except having changed the composition in the adhesive composition as shown in Table 1, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Comparative Example 1]

Except having changed the composition in the adhesive composition as shown in Table 1, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Comparative Example 2]

Except having changed the composition of the adhesive composition as shown in Table 1, and using a polybutylene terephthalate film having a thickness of 80 μm as a base material, it was carried out in the same manner as in Example 1, and a stealth was produced. Adhesive boards for cutting.

[Comparative Example 3]

Except having changed the composition of the adhesive composition as shown in Table 1, and using a polyethylene terephthalate film having a thickness of 50 μm as a base material, it was carried out in the same manner as in Example 1, and a stealth product was produced. Adhesive boards for cutting.

Here, the above-mentioned weight average molecular weight (Mw) is the weight average molecular weight in terms of polystyrene obtained by measurement (GPC measurement) using gel permeation chromatography (GPC) under the following conditions.

In addition, the details of the structural components shown in Table 1 are as follows.

[Composition of adhesive composition]

BA: n-butyl acrylate

MA: methyl acrylate

MMA: methyl methacrylate

EA: Ethyl Acrylate

HEA: 2-hydroxyethyl acrylate

[Material of base material]

PP: Polypropylene

EMAA: Ethylene-Methacrylic Acid Copolymer

PE: polyethylene

PBT: Polybutylene terephthalate

PET: polyethylene terephthalate

[Test Example 1] (Measurement of glass transition temperature)

Using a differential scanning calorimeter (manufactured by TA Instrument Japan, product name "DSC Q2000"), the adhesive layer constituting the adhesive sheets for stealth dicing produced in the Examples and Comparative Examples was measured at a heating and cooling rate of 20°C/min. The glass transition temperature Tg of the adhesive. The results are shown in Table 1.

[Test Example 2] (Measurement of the tensile modulus of elasticity of the base material)

The substrates produced in the examples and comparative examples were cut into test pieces of 15 mm×140 mm, and the tensile elastic coefficient was measured at a temperature of 23° C. and a relative humidity of 50% according to JIS K7161:2014. Specifically, the above-mentioned test piece was subjected to a tensile test at a speed of 200 mm/min using a tensile testing machine (manufactured by ORIENTEC, product name "TENSILON RTA-T-2M"), after setting the distance between the chucks to 100 mm. , to determine the tensile modulus of elasticity. In addition, the measurement was performed for both the extrusion direction (MD) and the direction (CD) at right angles to the base material during molding, and the average value of these measurement results was defined as the tensile modulus of elasticity elongation at break. The results are shown in Table 1.

[Test Example 3] (Evaluation of Solvent Resistance)

The peeling sheet was peeled off from the adhesive sheet for stealth dicing produced in the Example and the comparative example, and the peripheral edge part of the adhesive surface of the exposed adhesive layer was attached to a 6-inch ring frame, and used as an evaluation sample.

The surface of the annular frame side of this evaluation sample was turned up, and p-menthane as a solvent was dropped on the center portion of the adhesive surface of the adhesive layer. This dripping was performed until the solvent dripped to the whole area|region where the annular frame was not adhered on this adhesive surface, and it was left to stand for 5 minutes after the completion of dripping.

After that, the solvent was removed from the adhesive surface, and it was visually confirmed whether or not there was a change in the appearance of the adhesive sheet before and after the solvent was dropped, and the solvent resistance was evaluated. Then, those with no change in appearance were evaluated as "○", and those with appearance changes such as wrinkles or whitening were evaluated as "x".

[Test Example 4] (Evaluation of Heat Shrinkage)

The peeling sheet was peeled off from the adhesive sheet for stealth dicing manufactured in the Examples and Comparative Examples, and the adhesive surface of the exposed adhesive layer was applied with a sticking device (manufactured by LINTEC, product name "RAD-2700 F/12") , attached to a silicon wafer (outer diameter: 8 inches, thickness: 100μm, with dry polishing) and ring frame (stainless steel).

Then, the above-mentioned silicon wafer attached to the adhesive sheet for stealth dicing was irradiated with laser light with a wavelength of 1342 nm using a laser saw (manufactured by DISCO, product name "DFL7361"), so that the size of the obtained chip was 8 mm × 8 mm the modified part is formed in the silicon wafer.

Then, the silicon wafer and the ring frame on which the laser light was attached to which the adhesive sheet for stealth dicing was attached were set in a separation wafer expander (manufactured by DISCO, product name "DDS 2300"), and pulled down at 0°C. Expand at a speed of 100mm/sec and an expansion amount of 10mm (cold expansion). Thereby, the semiconductor wafer was divided in the reforming part, and a plurality of semiconductor wafers each having a wafer size of 8 mm×8 mm were obtained.

Then, the adhesive sheet for stealth dicing was expanded at a pull-down speed of 1 mm/sec and an expansion amount of 7 mm. After further maintaining the expanded state, the adhesive sheet for stealth dicing is sucked by the suction table, and then the area where the semiconductor wafer is attached and the area where the ring frame is attached in the adhesive sheet for stealth dicing is heated. The heating conditions at this time were as follows: the set temperature of the IR heater was 600° C., the rotation speed was 1 deg/sec, and the distance between the suction table supporting the adhesive sheet for stealth dicing and the heater was set to 13 mm. Thereby, the adhesive sheet for stealth dicing is heated to about 180 degreeC.

Then, the adhesive sheet for stealth dicing was released from the suction by the suction stage, the distance between adjacent semiconductor wafers was measured at 5 points, and the average value was calculated. Then, when the average value was 20 μm or more, it was evaluated as “○”, and when the average value was less than 20 μm, it was evaluated as “×”, and the heat shrinkability was evaluated. The results are shown in Table 1.

Table 1

As can be seen from Table 1, the adhesive sheets for stealth dicing obtained in the examples are excellent in solvent resistance and thermal shrinkage.

[industrial availability]

The adhesive sheet for stealth dicing of the present invention can be suitably used when a semiconductor wafer having through electrodes is used as an object to be processed.

Claims (12)

An adhesive sheet for stealth dicing, which is an adhesive sheet for stealth dicing comprising a base material and an adhesive layer laminated on one side of the base material, characterized in that: the base material has a tensile elasticity at 23° C. The coefficient is 50MPa or more and 450MPa or less, the base material is formed of at least one of a polyolefin-based film and an ethylene-based copolymer film, and the adhesive layer is composed of an energy ray-curable adhesive containing an acrylic copolymer, wherein This acrylic copolymer contains n-butyl acrylate, 2-hydroxyethyl acrylate, and alkyl (meth)acrylate having 2 or less carbon atoms in the alkyl group as constituent monomers. The adhesive sheet for stealth dicing according to claim 1, wherein, in all the monomers constituting the main chain of the acrylic copolymer, the content of the 2-hydroxyethyl acrylate is 5% by mass or more and 40% by mass Hereinafter, the content of the alkyl (meth)acrylate having the carbon number of the alkyl group of 2 or less is 5 mass % or more and 40 mass % or less in all the monomers constituting the main chain of the acrylic copolymer. The adhesive sheet for stealth dicing according to claim 1, wherein, among all the monomers constituting the main chain of the acrylic copolymer, the carbon number of the alkyl group is an alkyl (meth)acrylate of 2 or less. The mass ratio of the content to the content of the n-butyl acrylate is 0.08 or more and 1.0 or less, and among all the monomers constituting the main chain of the acrylic copolymer, the carbon number of the alkyl group is 2 or less (methyl) The mass ratio of the content of the alkyl acrylate to the content of the 2-hydroxyethyl acrylate is 0.3 or more and 4.0 or less. For the adhesive sheet for invisible dicing in item 1 of the scope of the application, wherein the The glass transition temperature (Tg) of the acrylic copolymer is -50°C or higher and 0°C or lower. As for the adhesive sheet for stealth dicing according to claim 1, wherein the dissolution parameter (SP value) of the acrylic copolymer is 9.06 or more and 10 or less. According to the adhesive sheet for stealth dicing according to claim 1, wherein the alkyl (meth)acrylate with the carbon number of the alkyl group being 2 or less is methyl methacrylate, methyl acrylate or ethyl acrylate. For the adhesive sheet for stealth dicing according to claim 1, wherein the base material is selected from the group consisting of random polypropylene, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and ethylene- At least one of (meth)acrylic copolymers is formed. The adhesive sheet for stealth dicing according to claim 1, wherein a semiconductor wafer having through electrodes is used as a processing object. The adhesive sheet for stealth dicing as claimed in claim 1 is used in a method of manufacturing a semiconductor device including a step of cleaning an object to be processed laminated on the adhesive sheet for stealth dicing with a solvent. The adhesive sheet for stealth dicing according to claim 1 of the scope of claim 1 is used in the adhesive sheet for stealth dicing on which the object to be laminated is applied to shrink the region where the object to be processed is not laminated by heating. In a method of manufacturing a semiconductor device. A method for manufacturing a semiconductor device, comprising: a step of back-grinding a single side of an object to be processed fixed on a hard support; transferring the object for which the back-grinding has been completed from the hard support To the transfer step of the side surface of the adhesive layer in the adhesive sheet for stealth dicing according to any one of items 1 to 10 of the scope of application; the process of laminating on the adhesive sheet for stealth dicing A cleaning step of cleaning an object with a solvent; a modified portion forming step of irradiating the cleaned object with laser light to form a modified portion in the object; and by using the adhesive sheet for stealth dicing A division step of expanding and dividing the object to be processed in the modified portion to obtain a plurality of pieces of the object to be processed. The method for manufacturing a semiconductor device according to claim 11 of the scope of the application includes: after the dividing step, the adhesive sheet for invisible dicing is expanded again to separate the plurality of pieces of the object to be processed from each other; the invisible dicing In the adhesive sheet for dicing, a heat shrinking step of shrinking the region of the object that is not laminated into a plurality of sheets by heating; A pick-up step in which the object to be processed is picked up from the adhesive sheet for stealth dicing.