TWI872019B - Adhesive tape and method for manufacturing semiconductor device - Google Patents

Abstract

The subject of the present invention is to reduce the transfer defects of the chip 21 from the back grinding tape 10 to the pick-up tape 30 or the connecting tape, especially when a pre-cutting method is used to manufacture a tiny semiconductor chip. In addition, its purpose is to improve the transfer efficiency of the chip from the back grinding tape 10 to the pick-up tape 30 or the connecting tape. The solution of the present invention is to provide an adhesive tape 10, which is used as the above-mentioned back grinding tape and includes a substrate 11 and an adhesive layer 12 arranged on one side of the substrate, and its characteristics are: the aforementioned adhesive layer 12 is composed of an energy-ray-curable adhesive; and the adhesive after being cured by energy-ray irradiation has a storage elastic modulus _E'200 of 1.5MPa or more at 200°C.

Description

Adhesive tape and method for manufacturing semiconductor device

The present invention relates to an adhesive tape, and more particularly, to an adhesive tape suitable for temporarily fixing semiconductor wafers and chips when a semiconductor device is manufactured using a so-called predicing method, and a method for manufacturing a semiconductor device using the adhesive tape.

As various electronic devices are becoming more miniaturized and multifunctional, the semiconductor chips they carry are also required to be miniaturized and thinned. In order to thin the chips, the back of the semiconductor wafer is usually ground to adjust the thickness. In addition, there is also a technology called pre-cutting method, which is to form a groove of a predetermined depth on the surface side of the wafer, and then grind from the back side of the wafer. The bottom of the groove is removed by grinding to separate the wafer into pieces and obtain a chip. In the pre-cutting method, because the back grinding of the wafer and the singulation of the wafer can be performed at the same time, thin chips can be manufactured efficiently.

Previously, when grinding the back side of a semiconductor wafer and manufacturing chips using a pre-cutting method, an adhesive tape called a back grinding sheet was usually attached to the surface of the wafer to protect the circuits on the surface of the wafer in advance and to fix the semiconductor wafer and the semiconductor chip.

The following will explain the process of singulating the wafer using the pre-cutting method and then picking up the wafer with reference to the drawings. The semiconductor wafer is singulated by pre-cutting, and a wafer group 20 consisting of a plurality of singulated wafers 21 can be obtained on the back grinding tape 10 (FIG. 1). The wafer group 20 is transferred to an adhesive tape called a pick-up tape 30, and after the wafer spacing is expanded as needed, it is peeled off from the pick-up tape 30 (Patent Document 1: Patent Gazette No. 2012-209385). As the pick-up tape 30, an adhesive tape of the type used as a dicing tape is often used. The wafer group 20 is transferred from the back grinding tape 10 to the pick-up tape 30 as follows. That is, the pick-up tape 30 is attached to the wafer group 20 held on the back grinding tape 10. At this time, the outer periphery of the pick-up tape 30 is fixed using the ring frame 40 (FIG. 2). Next, the wafer group 20 can be transferred to the pick-up tape 30 by only peeling off the back grinding tape 10.

In the back grinding step, the back grinding tape 10 must have an adhesive force that can stably hold the wafer and the chip group, and must have an adhesive force that can be easily peeled off from the chip surface when the chip group is transferred to the pickup tape 30. Therefore, the adhesive layer 12 of the back grinding tape 10 is mostly made of an energy-ray-curable adhesive that can reduce the adhesive force by energy-ray irradiation. For example, Patent Document 2 (Japanese Patent Publication No. 2002-053819) discloses a back grinding tape whose adhesive force before energy-ray curing is more than 150g/25mm and whose adhesive force after energy-ray curing becomes less than 150g/25mm. The adhesive force here is the adhesive force measured according to the method specified in JIS Z-0237, using a SUS304-BA plate as the adherend and under the conditions of a peeling speed of 300 mm/min and a peeling angle of 180 degrees.

In addition, Patent Document 3 (Patent Publication No. 2016-72546) discloses an adhesive tape for protecting the surface of semiconductor wafers used in a pre-cutting method. The purpose of the adhesive tape is to suppress kerf shift during pre-cutting and eliminate the transfer of adhesive to the semiconductor chip and the poor peeling of the semiconductor chip. The substrate of the adhesive tape is specifically provided with at least one rigid layer with a tensile modulus of 1 to 10 GPa, and the peeling force of the adhesive layer at a peeling angle of 30° after radiation curing is 0.1 to 3.0 N/25 mm.

When the back grinding tape 10 is peeled off, the peeling tape 50 that serves as the trigger for peeling is fixed to the back side (substrate side (FIG. 3)) of the back grinding tape 10. The back grinding tape is roughly the same shape as the semiconductor wafer, and since there is no starting point for peeling off, the thin rectangular peeling tape 50 is fixed to serve as the starting point for peeling off. The peeling tape 50 is strongly fixed to the back side of the back grinding tape 10 by heat pressing. Prior technical literature Patent literature

[Patent Document 1] Japanese Patent Publication No. 2012-209385 [Patent Document 2] Japanese Patent Publication No. 2002-053819 [Patent Document 3] Japanese Patent Publication No. 2016-72546

Invention Problems to be Solved

When the peeling tape 50 is heat-pressed to the back grinding tape 10, the peeling tape 50 is heat-sealed to the back of the back grinding tape 10 by heating to about 140-230°C and applying pressure. Therefore, the adhesive layer of the back grinding tape at the heat-sealed portion is also heated and pressurized. As a result, the adhesive layer hardened by the energy ray irradiation flows and activates due to the heating and pressurization, and the hardened adhesive layer of the back grinding tape is heat-pressed to the wafer. In this state, when the back grinding tape 10 is peeled off starting from the peeling tape, the back grinding tape is peeled off while the wafer 21 is fixed to the back grinding tape 10 at the heat-sealed portion and its vicinity, resulting in a decrease in the wafer yield (FIG. 4 and FIG. 5). Hereinafter, this phenomenon is referred to as "wafer transfer failure".

When the wafer size is large, although the back grinding tape and the wafer surface can be peeled off well, as the wafer size decreases, the wafer is easily buried in the adhesive layer 12 of the back grinding tape. As a result, it becomes more difficult to peel the wafer from the back grinding tape and the transfer failure of the wafer increases. In addition, since a relatively hard substrate is often used as the substrate 11 of the back grinding tape in the pre-cutting method, the back grinding tape cannot be fully folded back when peeling, which also makes peeling difficult and becomes the main reason for the increase of transfer failure.

In Patent Document 3, since the substrate is hard, it is difficult to bend the adhesive tape. Therefore, the peeling angle becomes sharp, resulting in a strong peeling force and a time-consuming peeling process.

Therefore, the purpose of the present invention is to reduce the transfer failure of the chip 21 when transferring the chip group 20 from the back grinding tape 10 to other tapes such as the pick-up tape or the tape following the tape, especially when the micro semiconductor chip is manufactured by the pre-cutting method. Moreover, the purpose is to improve the transfer efficiency of the chip from the back grinding tape to other tapes such as the pick-up tape or the tape following the tape. Means for solving the problem

The purpose of the present invention is to solve this problem, and its gist is as follows: (1) An adhesive tape comprising a substrate and an adhesive layer disposed on one side of the substrate, wherein: the adhesive layer is composed of an energy-ray-curable adhesive; and the adhesive hardened by energy-ray irradiation has a storage elastic modulus _E'200 at 200°C of 1.5 MPa or more. (2) The adhesive tape as described in (1) is used as the aforementioned back grinding tape in a method for manufacturing a semiconductor device, which comprises the steps of attaching a grinding tape to the surface of a semiconductor wafer having grooves formed thereon, grinding the back side and singulating the semiconductor wafer into semiconductor chips by the grinding, and then transferring the singulated chip group to a pickup tape or a connecting tape. (3) A method for manufacturing a semiconductor device, comprising attaching a grinding tape to the surface of a semiconductor wafer having grooves formed thereon, grinding the back side and singulating the semiconductor wafer into semiconductor chips by the grinding, and then transferring the singulated chip group to a pickup tape or a connecting tape, using the adhesive tape described in (1) as the aforementioned back grinding tape. (4) A use of an adhesive tape, which is the use of the adhesive tape as described in (1) above, in a method for manufacturing a semiconductor device, which includes the steps of attaching a grinding tape to the surface of a semiconductor wafer having grooves formed thereon, grinding the back surface and singulating the semiconductor wafer into semiconductor chips by the grinding, and then transferring the singulated chip group to a pickup tape or a tape, which is the use of the back grinding tape. Effect of the Invention

According to the adhesive tape 10 of the present invention, after the energy beam curable adhesive layer is cured, even if the peeling tape 50 is thermally pressed, the adhesion between the adherend (semiconductor chip) and the adhesive tape is suppressed to a very low level, thereby preventing poor transfer of the chip.

The form used to implement the invention

The adhesive tape of the present invention is described in detail below. First, the main terms used in this specification are described. In this specification, for example, "(meth)acrylate" is used as a term to represent both "acrylate" and "methacrylate", and the same applies to other similar terms.

The so-called adhesive tape means a laminate including a substrate and an adhesive layer provided on one side thereof, and may also include other constituent layers other than the above. For example, a primer layer (easy-to-adhere layer) may be formed on the surface of the substrate on the side of the adhesive layer, and a peeling sheet may be stacked on the surface of the adhesive layer to protect the adhesive layer until use. In addition, the substrate may be a single layer or a multi-layer. The same applies to the adhesive layer. The so-called "surface" of a semiconductor wafer refers to the side where the circuit is formed, and the "back side" refers to the side where the circuit is not formed. The so-called singulation of a semiconductor wafer refers to dividing the semiconductor wafer into circuit units to obtain semiconductor chips.

The so-called bare silicon wafer is a silicon wafer before patterning and other processing, and the surface is mirror-polished. The so-called pre-cutting method refers to a method of forming a groove of a predetermined depth from the surface side of the wafer, and then grinding from the back side of the wafer to separate the wafers by grinding.

The so-called back grinding tape is an adhesive tape used to protect the wafer electrical path surface when grinding the back side of a semiconductor wafer. In particular, in this manual, it refers to an adhesive tape suitable for use in the pre-cutting method. The so-called pick-up tape is an adhesive tape used to transfer and pick up a chip group. Typically, an adhesive tape called a dicing tape can be used. The so-called adhesive tape means a thin layer that functions as an adhesive. Various tapes are used to transfer the adhesive layer to other objects to be bonded. Specifically, there can be cited a laminate of a film-like adhesive and a peeling sheet, a laminate of a dicing tape and a film-like adhesive, a dicing/die bonding tape composed of an adhesive layer having the functions of both a dicing tape and a die bonding tape, and a peeling sheet, and the like.

The adhesive tape of the present invention can be used as the above-mentioned back grinding tape in particular. The adhesive tape 10 of the present invention includes a substrate 11 and an adhesive layer 12 provided on one side thereof. The following describes in more detail the composition of each component of the adhesive tape 10 of the present invention. [Substrate 11] The substrate 11 of the adhesive tape 10 can use various resin films used as substrates of back grinding tapes.

An example of the substrate 11 used in the present invention is described in detail below, but it is described only because the substrate is easily available and should not be interpreted in any limiting sense.

The substrate of the present invention may be, for example, a relatively hard resin film. In addition, a buffer layer composed of a relatively soft resin film may be laminated on one or both sides of the substrate.

The Young's modulus of the substrate is preferably 1000 MPa or more. When a substrate with a Young's modulus of less than 1000 MPa is used, the holding performance of the adhesive tape on the semiconductor wafer or semiconductor chip is reduced, and vibration cannot be suppressed during back grinding, and the semiconductor chip is easily damaged or damaged. On the other hand, by setting the Young's modulus of the substrate to 1000 MPa or more, the holding performance of the adhesive tape on the semiconductor wafer or semiconductor chip is improved, vibration can be suppressed during back grinding, and the semiconductor chip can be prevented from being damaged or damaged. In addition, the stress when the adhesive tape is peeled off from the semiconductor chip can be reduced, and the chip defects and damage caused by peeling the tape can be prevented. Furthermore, the workability when attaching the adhesive tape to the semiconductor wafer can also be improved. From this point of view, the Young's modulus of the substrate is preferably 1800~30000MPa, and preferably 2500~6000MPa.

The thickness (D1) of the substrate 11 is not particularly limited, and is preferably 500 μm or less, more preferably 15 to 350 μm, and even more preferably 20 to 160 μm. By setting the thickness of the substrate to 500 μm or less, it is easy to control the peeling force of the adhesive tape. In addition, by setting the thickness of the substrate to 15 μm or more, the substrate can easily achieve the function of a support for the adhesive tape.

As the material of the substrate 11, various resin films can be used. Here, as the substrate having a Young's modulus of 1000 MPa or more, for example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyether ketone, biaxially stretched polypropylene, etc. can be cited. Among these resin films, a film containing at least one selected from polyester film, polyamide film, polyimide film, and biaxially stretched polypropylene film is preferred, a polyester film is more preferred, and a polyethylene terephthalate film is more preferred.

Furthermore, the substrate may contain plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, catalysts, etc. within the scope of not impairing the effect of the present invention. Furthermore, the substrate is transparent to the energy line irradiated when the adhesive layer is cured. Moreover, a bonding treatment such as a corona treatment may be performed on at least one surface of the substrate to improve the adhesion with at least one of the buffer layer and the adhesive layer. Furthermore, the substrate may also be a thing having the above-mentioned resin film and a coating on at least one surface of the resin film. Easy to bond layer (primer layer).

The composition for forming the easy-adhesion layer is not particularly limited, and for example, compositions containing polyester resins, urethane resins, polyesterurethane resins, acrylic resins, etc. can be cited. The composition for forming the easy-adhesion layer can also contain a crosslinking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, a rustproofing agent, a pigment, a dye, etc. as needed. The thickness of the easy-adhesion layer is preferably 0.01~10μm, and preferably 0.03~5μm. Furthermore, since the thickness of the easy-adhesion layer is smaller than that of the substrate and the material is softer, the influence on the Young's modulus is smaller. Even when the easy-adhesion layer is provided, the Young's modulus of the substrate is substantially the same as that of the resin film.

[Buffer layer] A buffer layer may be provided on one or both sides of the substrate 11. The buffer layer is composed of a relatively soft resin film, which can mitigate vibration caused by grinding of the semiconductor wafer and prevent cracks and defects from occurring in the semiconductor wafer. In addition, the semiconductor wafer with the adhesive tape attached is placed on the adsorption machine during back grinding, and the adhesive tape is provided with a buffer layer, so that it is easy to be properly held on the adsorption machine.

The thickness (D2) of the buffer layer is preferably 8-80 μm, more preferably 10-60 μm.

The buffer layer is preferably a polypropylene film, an ethylene-vinyl acetate copolymer film, an ionic polymer resin film, an ethylene-(meth)acrylic acid copolymer film, an ethylene-(meth)acrylic acid ester copolymer film, an LDPE film, or an LLDPE film. Alternatively, the buffer layer may be formed of a buffer layer-forming composition containing an energy ray polymerizable compound. The substrate having the buffer layer can be obtained by laminating the substrate to the above-mentioned film.

[Adhesive layer 12] The adhesive layer 12 is formed on one side of the substrate 11 directly or via a buffer layer. In the present invention, the adhesive layer is composed of an energy-ray-curable adhesive, and the adhesive after curing has a storage elastic modulus _E'200 of 1.5 MPa or more at 200°C. Hereinafter, the storage elastic modulus of the adhesive at 200°C after curing may be referred to as the storage elastic modulus after curing.

The storage elastic modulus after curing can be controlled by the composition of the adhesive. The general method for controlling the storage elastic modulus after curing is described below. The storage elastic modulus _E'200 of the adhesive after curing by energy beam irradiation at 200°C is preferably in the range of 2.0~100MPa, and more preferably in the range of 2.5~70MPa. By setting the storage elastic modulus _E'200 after curing to be in the above range, the chip group 20 can be stably held even after the adhesive layer is cured, and when the chip group is transferred to the pickup tape 30 or the connecting tape, the adhesive layer can be easily peeled off from the chip group without leaving any residue. When measuring the elastic modulus after curing and storage, the adhesive can be completely cured by energy ray irradiation. In other words, the adhesive is cured to the extent that the elastic modulus does not change even if further energy ray irradiation is performed.

In addition, the storage elastic modulus of a cured adhesive is usually high at room temperature, and tends to decrease as the temperature rises. However, the adhesive of the present invention maintains a high storage elastic modulus after curing even at high temperatures.

Therefore, even if the peeling tape 50 is hot-pressed at a high temperature, the hardened adhesive layer is not easy to soften when the adhesive tape of the present invention is used. As a result, even if the peeling tape is hot-pressed at a high temperature, chip transfer failure can be greatly reduced.

In addition, the storage elastic modulus of the adhesive at 23°C before energy beam curing is preferably 0.05~0.50MPa. Moreover, the loss positive contact (tanδ=loss elastic modulus/storage elastic modulus) at 23°C before energy beam curing is preferably above 0.2. On the surface of the semiconductor wafer, circuits are formed and usually have bumps. By making the storage elastic modulus and tanδ of the adhesive within the above range, when the adhesive tape is attached to the bumpy wafer surface, the bumps on the wafer surface can be fully contacted with the adhesive layer and the adhesion of the adhesive layer can be properly exerted. Therefore, the adhesive tape can be fixed to the semiconductor wafer reliably and the wafer surface can be properly protected during back grinding. From these viewpoints, the storage elastic modulus of the adhesive at 23°C before energy ray curing is preferably 0.10~0.35MPa.

Since the storage elastic modulus _E'200 after curing is within the above range, even if the peeling tape 50 is heat-pressed at a high temperature, the chip and the like will not be buried in the adhesive layer and the transfer failure of the chip can be greatly reduced. For example, after the adhesive layer 12 of the adhesive tape 10 is attached to the silicon wafer mirror surface, the adhesive layer is irradiated with energy rays to be cured, and after hot pressing at a pressure of 0.5 N/cm ² and 210° C. for 5 seconds, the adhesive force between the silicon wafer mirror surface and the adhesive layer at 23° C. (hereinafter referred to as "adhesion after hot pressing") is preferably 9.0 N/25 mm or less, more preferably 0.001 to 7 N/25 mm, and even more preferably 0.1 to 1 N/25 mm. In addition, the adhesive layer has appropriate pressure-sensitive adhesiveness at room temperature before energy ray curing. The adhesion of the adhesive layer to the silicon wafer mirror surface at 23°C before energy ray curing is preferably in the range of 10~1500mN/25mm, more preferably 10~700mN/25mm.

When measuring the adhesion after hot pressing, the adhesive layer is completely hardened by irradiation with energy beams. That is, it is hardened to the extent that the adhesion does not decrease even if the energy beam is further irradiated. Hot pressing is performed using a heat press or the like. At this time, the peeling tape 50 described later is simultaneously hot pressed on the substrate side surface of the adhesive tape. The peeling tape 50 serves as the starting point for peeling, and can also be used in conjunction with a measuring device. In addition, in the measurement of the adhesion after hot pressing described later, the measured adhesion may change as the peeling progresses. In the present invention, the maximum value until the peeling of the adhesive tape 10 is completed is referred to as the adhesive force after heat-press bonding.

The thickness (D3) of the adhesive layer 12 is preferably less than 200 μm, more preferably 5 to 55 μm, and even more preferably 10 to 50 μm. When the adhesive layer is thinned in this way, the proportion of the lower rigidity portion of the adhesive tape can be reduced, so it is easier to further prevent semiconductor chip defects generated during back grinding.

The adhesive layer 12 is formed of an energy ray-curable adhesive having an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, etc. as a main agent, and the acrylic energy ray-curable adhesive is preferred.

Furthermore, the adhesive layer 12 is formed by an energy-ray-curable adhesive, and before being cured by energy ray irradiation, the elastic modulus at 23°C can be set within the above range, and the peeling force can be easily set to 1000mN/50mm or less after curing. Moreover, the adhesive force referred to here refers to the adhesive force of the adhesive tape excluding the heat-sealed portion described later.

Furthermore, the fracture stress of the adhesive layer 12 after energy ray curing is preferably 10 MPa or more, and particularly preferably 15 MPa or more. Furthermore, the fracture elongation after energy ray curing is preferably 15% or more, and particularly preferably 20% or more. Thus, when the fracture stress value is 10 MPa or more and the fracture elongation value is 15% or more, the tensile properties of the energy ray curable adhesive layer are good, and even when the irradiation of ultraviolet rays or the like is insufficient and the energy ray curable adhesive layer is not sufficiently cured, the adhesive residue can be prevented from being attached to the wafer.

Specific examples of adhesives are described in detail below, but they are non-limiting examples, and the adhesive layer of the present invention should not be construed as being limited to these specific examples. As energy ray-hardening adhesives, for example, in addition to non-energy ray-hardening adhesive resins (also referred to as "adhesive resin I"), energy ray-hardening adhesive compositions (hereinafter also referred to as "X-type adhesive compositions") containing energy ray-hardening compounds other than adhesive resins can also be used. Furthermore, as an energy ray-curable adhesive, an adhesive composition (hereinafter also referred to as a "Y-type adhesive composition") containing an energy ray-curable adhesive resin (hereinafter also referred to as "adhesive resin II") as a main component and containing no energy ray-curable compound other than the adhesive resin may be used.

Furthermore, as the energy ray-curable adhesive, a combination of X-type and Y-type, that is, an energy ray-curable adhesive composition containing an energy ray-curable compound other than the adhesive resin in addition to the energy ray-curable adhesive resin II (hereinafter also referred to as an "XY-type adhesive composition") can also be used. Among these, the use of the XY-type adhesive composition is preferred. By using the XY-type, sufficient adhesion properties are obtained before curing, and on the other hand, the peeling force on the semiconductor wafer can be sufficiently reduced after curing.

In the following description, "adhesive resin" is used as a term to refer to one or both of the above-mentioned adhesive resin I and adhesive resin II. As specific adhesive resins, for example, acrylic resins, urethane resins, rubber resins, silicone resins, etc. can be cited, and acrylic resins are preferred. Hereinafter, as the adhesive resin, an acrylic adhesive using an acrylic resin is described in more detail.

The acrylic resin can use an acrylic polymer (b). The acrylic polymer (b) is obtained by polymerizing a monomer containing at least an alkyl (meth)acrylate and contains a structural unit derived from an alkyl (meth)acrylate. As the alkyl (meth)acrylate, there can be cited those having an alkyl group with 1 to 20 carbon atoms, and the alkyl group can be a straight chain or a branched chain. As specific examples of the alkyl (meth)acrylate, there can be cited methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, and the like. The alkyl (meth)acrylate can be used alone or in combination of two or more.

Furthermore, from the viewpoint of improving the adhesive force of the adhesive layer, the acrylic polymer (b) preferably contains a structural unit derived from an alkyl (meth)acrylate having an alkyl group with a carbon number of 4 or more. The carbon number of the alkyl (meth)acrylate is preferably 4 to 12, more preferably 4 to 6. Furthermore, the alkyl (meth)acrylate having an alkyl group with a carbon number of 4 or more is preferably an alkyl acrylate.

In the acrylic polymer (b), the amount of the (meth)acrylic acid alkyl ester having an alkyl group with 4 or more carbon atoms is preferably 40 to 98% by mass, more preferably 45 to 95% by mass, and even more preferably 50 to 90% by mass, relative to the total amount of monomers constituting the acrylic polymer (b) (hereinafter also referred to as "total amount of monomers").

The acrylic polymer (b) is preferably a copolymer containing structural units derived from (meth)acrylic acid alkyl esters having 4 or more carbon atoms in the alkyl group, in order to adjust the elastic modulus and adhesive properties of the adhesive layer; and the (meth)acrylic acid alkyl esters are preferably (meth)acrylic acid alkyl esters having 1 to 3 carbon atoms in the alkyl group; and the (meth)acrylic acid alkyl esters are preferably (meth)acrylic acid alkyl esters having 1 or 2 carbon atoms, more preferably (meth)acrylate, and most preferably methyl methacrylate. In the acrylic polymer (b), the (meth)acrylic acid alkyl esters having 1 to 3 carbon atoms in the alkyl group are preferably 1 to 30 mass %, preferably 3 to 26 mass %, and more preferably 6 to 22 mass %, relative to the total amount of the monomers.

The acrylic polymer (b) preferably has a structural unit derived from a monomer containing a functional group in addition to the structural unit derived from the above-mentioned (meth) alkyl ester. Examples of the functional group of the monomer containing a functional group include a hydroxyl group, a carboxyl group, an amino group, and an epoxy group. The monomer containing a functional group is capable of reacting with a crosslinking agent described below to become a crosslinking starting point, or reacting with an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the acrylic polymer (b).

As the functional group-containing monomer, there can be mentioned a hydroxyl-containing monomer, a carboxyl-containing monomer, an amine-containing monomer, an epoxy-containing monomer, etc. These monomers can be used alone or in combination of two or more. Among these, a hydroxyl-containing monomer and a carboxyl-containing monomer are preferred, and a hydroxyl-containing monomer is more preferred.

Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and unsaturated alcohols such as vinyl alcohol and allyl alcohols.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, and citric acid; and their anhydrides; and 2-carboxyethyl methacrylate.

The amount of the functional monomer is preferably 1 to 35% by mass, preferably 3 to 32% by mass, and more preferably 6 to 30% by mass, relative to the total amount of monomers constituting the acrylic polymer (b). In addition, the acrylic polymer (b) may contain structural units derived from monomers copolymerizable with the acrylic monomers, such as styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide, in addition to the above.

The acrylic polymer (b) can be used as a non-energy ray-curable adhesive resin I (acrylic resin). Energy ray-curable acrylic resins include those obtained by reacting a compound having a photopolymerizable unsaturated group (also referred to as an unsaturated group-containing compound) with a functional group of the acrylic polymer (b).

The unsaturated group-containing compound is a compound having both a substituent capable of bonding to the functional group of the acrylic polymer (b) and a photopolymerizable unsaturated group. As the photopolymerizable unsaturated group, (meth)acryloyl, vinyl, furyl, etc. can be cited, and (meth)acryloyl is preferred. In addition, as a substituent capable of bonding to the functional group possessed by the unsaturated group-containing compound, an isocyanate group, a glycidyl group, etc. can be cited. Therefore, as an unsaturated group-containing compound, for example, (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, (meth)glycidyl acrylate, etc. can be cited.

Furthermore, it is preferred that the unsaturated group-containing compound reacts with a portion of the functional groups of the acrylic polymer (b). Specifically, it is preferred that the unsaturated group-containing compound reacts with 50 to 98 mol% of the functional groups of the acrylic polymer (b), and it is more preferred that the unsaturated group-containing compound reacts with 55 to 93 mol%. In this way, in the energy-ray-curable acrylic resin, a portion of the functional groups do not react with the unsaturated group-containing compound and remain, and are easily cross-linked by a crosslinking agent. In addition, the weight average molecular weight (Mw) of the acrylic resin is preferably 300,000 to 1.6 million, preferably 400,000 to 1.4 million, and more preferably 500,000 to 1.2 million. Furthermore, the glass transition temperature (Tg) of the acrylic resin is preferably -70 to 10°C.

(Energy ray-hardening compound) As the energy ray-hardening compound contained in the X-type or XY-type adhesive composition, it is preferably a monomer or oligomer having an unsaturated group in the molecule and capable of being polymerized and hardened by energy ray irradiation. As such energy ray-hardening compounds, for example, poly(meth)acrylate monomers such as trihydroxymethylpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol (meth)acrylate, and oligomers such as urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and epoxy (meth)acrylate can be cited. The molecular weight (weight average molecular weight in the case of an oligomer) of the energy ray-curable compound is preferably 100 to 12,000, more preferably 200 to 10,000, more preferably 400 to 8,000, and particularly preferably 600 to 6,000.

Among these, urethane (meth)acrylate oligomers are preferred because they have a high molecular weight and are less likely to reduce the elastic modulus of the adhesive layer.

Preferred urethane (meth) acrylate oligomers are compounds containing isocyanate units and polyol units and having a (meth) acryloyl group at the terminal. Urethane (meth) acrylates include compounds obtained by reacting a polyol having a hydroxyl group at the terminal, such as an alkylene polyol, a polyether compound, or a polyester compound, with a polyisocyanate to generate a urethane oligomer, and reacting a compound having a (meth) acryloyl group with the functional group at the terminal. Such urethane (meth) acrylates have energy ray curability due to the (meth) acryloyl group.

As the above-mentioned polyisocyanate, diisocyanates such as isophorone diisocyanate (IPDI), 1,3-bis-(isocyanatomethyl)-cyclohexane (H6XDI), and 4,4'-dicyclohexylmethane diisocyanate (H12MDI) can be used. These polyisocyanates are preferably used in an amount of 40 to 49 mol% in the energy ray-curable urethane (meth)acrylate. Moreover, among these diisocyanates, isophorone diisocyanate (IPDI) is particularly preferably used because it can improve the compatibility of the energy ray-curable urethane (meth)acrylate with the energy ray-curable acrylic polymer.

As the acrylate for forming the (meth)acryl group, 2-hydroxypropyl acrylate (2HPA), 2-hydroxyethyl acrylate (2HEA), etc. can be used. These acrylates are preferably used in an amount of 4 to 40 mol% in the energy-ray-curable urethane (meth)acrylate.

The energy ray-curable urethane (meth) acrylate is preferably used in a ratio of 1 to 200 parts by mass, preferably 5 to 100 parts by mass, and more preferably 10 to 50 parts by mass, relative to 100 parts by mass of the energy ray-curable acrylic polymer. In addition, from the viewpoint of compatibility with the energy ray-curable acrylic polymer and processability of the energy ray-curable adhesive layer, the molecular weight of the urethane (meth) acrylate is preferably set to a range of about 300 to 30,000 in terms of number average molecular weight, and is preferably 20,000 or less, for example, an oligomer of 1,000 to 15,000.

The content of the energy ray curing compound in the X-type adhesive composition is preferably 40 to 200 parts by mass, preferably 50 to 150 parts by mass, and more preferably 60 to 90 parts by mass relative to 100 parts by mass of the adhesive resin. On the other hand, the content of the energy ray curing compound in the XY-type adhesive composition is preferably 1 to 30 parts by mass, preferably 2 to 20 parts by mass, and more preferably 3 to 15 parts by mass relative to 100 parts by mass of the adhesive resin. In the XY-type adhesive composition, since the adhesive resin is energy ray curable, even if the content of the energy ray curing compound is small, the peeling force can be sufficiently reduced after energy ray irradiation.

(Crosslinking agent) The adhesive composition preferably further contains a crosslinking agent. The crosslinking agent is, for example, a substance that reacts with a functional group of a functional group monomer of the adhesive resin to crosslink the adhesive resins. Examples of the crosslinking agent include isocyanate-based crosslinking agents such as toluene diisocyanate, hexamethylene diisocyanate, and adducts thereof; epoxy-based crosslinking agents such as 1,3-bis(N,N'-diepoxypropylaminomethyl)cyclohexane; azoxypropane-based crosslinking agents such as hexa[1-(2-methyl)-azoxypropane]triphosphatriazine; and clump-based crosslinking agents such as aluminum clumps. These crosslinking agents may be used alone or in combination of two or more.

Among these, isocyanate-based crosslinking agents are preferred from the perspective of increasing cohesive force and thus enhancing adhesive force, and from the perspective of ease of acquisition. From the perspective of promoting the crosslinking reaction, the amount of the crosslinking agent to be added is preferably 0.01 to 10 parts by mass, preferably 0.03 to 7 parts by mass, and more preferably 0.05 to 4 parts by mass relative to 100 parts by mass of the adhesive resin.

(Photopolymerization initiator) In addition, when the adhesive composition is energy-ray-curable, it is preferable that the adhesive composition further contains a photopolymerization initiator. By containing a photopolymerization initiator, even with energy rays of lower energy such as ultraviolet rays, the curing reaction of the adhesive composition can be fully carried out.

As the photopolymerization initiator, for example, benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, 9-oxosulfuron compounds can be cited. Compounds, peroxide compounds, and photosensitizers such as amines and benzoquinones, etc., more specifically, for example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, diacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, etc. can be cited.

These photopolymerization initiators can be used alone or in combination of two or more. The amount of the photopolymerization initiator to be added is preferably 0.01 to 10 parts by mass, preferably 0.03 to 5 parts by mass, and more preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the adhesive resin.

(Other additives) The adhesive composition may contain other additives within the range that does not impair the effects of the present invention. Examples of other additives include antistatic agents, antioxidants, softeners (plasticizers), fillers, rustproofing agents, pigments, dyes, etc. When these additives are prepared, the amount of the additive is preferably 0.01 to 6 parts by mass relative to 100 parts by mass of the adhesive resin.

In addition, from the viewpoint of improving the coating property on the substrate, the peeling sheet, etc., the adhesive composition can also be further diluted with an organic solvent to form a solution of the adhesive composition. As the organic solvent, for example, methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, etc. can be cited. In addition, these organic solvents can also be used directly as the organic solvents used in the synthesis of the adhesive resin, and it is also possible to add one or more organic solvents other than the organic solvents used in the synthesis in a manner that the solution of the adhesive composition can be uniformly coated.

(Control of storage elastic modulus after curing) By setting the storage elastic modulus _E'200 after curing of the energy beam curable adhesive constituting the above-mentioned adhesive layer 12 to the above-mentioned range, even if the peeling tape 50 is hot-pressed, the chip will not be buried in the adhesive layer and the transfer defect of the chip can be greatly reduced.

The storage modulus of elasticity after curing can be controlled by the composition of the adhesive. For example, the storage modulus of elasticity after curing can be increased by increasing the crosslinking degree of the adhesive after energy ray curing. Therefore, by increasing the amount of crosslinking agent in the adhesive or using a crosslinking agent with a large number of functional groups, the crosslinking degree of the adhesive becomes higher and the storage modulus of elasticity after hot pressing can be increased. In addition, as an adhesive resin, the storage modulus of elasticity after curing can be increased by using an acrylic resin with a higher Tg.

However, when these methods are used, the elastic modulus before energy ray curing becomes high and sufficient pressure-sensitive adhesiveness may not be obtained before energy ray curing. Therefore, for example, it is also effective to increase the density of energy ray polymerizable unsaturated groups contained in the adhesive. Specifically, by increasing the amount of energy ray polymerizable unsaturated groups introduced into the energy ray curable adhesive resin II, increasing the amount of energy ray curable compound, using a compound with a large number of unsaturated groups as the energy ray curable compound, or by increasing the amount of photopolymerization initiator, a highly cross-linked structure can be formed by energy ray curing, and the storage elastic modulus after curing can be controlled to be higher.

Generally, the storage modulus of the adhesive after curing is high at room temperature, and tends to decrease as the temperature rises. However, by introducing a highly cross-linked structure into the adhesive, the adhesive layer softens at high temperatures, and the flow is suppressed, thereby maintaining a high storage modulus. As a result, even if the peeling tape 50 is heat-pressed, the chip or the like is not buried in the adhesive layer, and transfer failure can be suppressed.

Furthermore, when the storage elastic modulus after curing is high, the adhesive tape is difficult to deform and the cured adhesive tape may be difficult to peel off. In this case, by using a substrate with high flexibility as the substrate 11, it may be easy to peel off. When the substrate is relatively flexible, the adhesive tape 10 can be folded back during peeling and the peeling angle becomes larger. Therefore, since the contact area between the chip and the adhesive layer becomes smaller in the part where peeling is in progress, it can be peeled off with less force. On the other hand, if the substrate is too hard, the peeling angle becomes smaller, and the contact area between the chip and the adhesive layer becomes larger in the part where the peeling is in progress, and the adhesion (peeling force) becomes higher. For the same reason, thinning the thickness of the substrate is also effective in terms of easy peeling. However, if the substrate is too soft or too thin, the operability of the adhesive tape is reduced, and there is a possibility that vibration during back grinding cannot be suppressed, or the semiconductor chip may be damaged or damaged.

Therefore, it is preferable to control the releasability of the adhesive tape 10 by appropriately setting the physical properties of the adhesive layer 12 and the Young's modulus and thickness of the substrate 11.

[Peeling sheet] A peeling sheet may be attached to the surface of the adhesive tape. Specifically, the peeling sheet is attached to the surface of the adhesive layer of the adhesive tape. The peeling sheet protects the adhesive layer during transportation and storage by being attached to the surface of the adhesive layer. The peeling sheet is attached to the adhesive tape in a removable manner and is peeled off from the adhesive tape before the adhesive tape is used (i.e., before the backside of the wafer is ground). The release sheet is a release sheet having at least one side subjected to a release treatment. Specifically, a release sheet having a release agent applied to the surface of a release sheet substrate can be cited.

As a substrate for a peeling sheet, a resin film is preferred. As a resin constituting the resin film, for example, polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin, polyolefin resins such as polypropylene resin and polyethylene resin, etc. can be cited. As a peeling agent, for example, rubber elastomers such as polysilicone resins, olefin resins, isoprene resins, and butadiene resins, long-chain alkyl resins, alkyd resins, fluorine resins, etc. can be cited. The thickness of the peeling sheet is not particularly limited, but is preferably 10 to 200 μm, more preferably 20 to 150 μm.

(Manufacturing method of adhesive tape 10) The manufacturing method of the adhesive tape 10 of the present invention is not particularly limited, and it can be manufactured using a known method. For example, an adhesive layer provided on a release sheet can be bonded to one side of a substrate to manufacture an adhesive tape having a release sheet attached to the surface of the adhesive layer. The release sheet attached to the surface of the adhesive layer can be appropriately peeled off and removed before using the adhesive tape. As a method for forming an adhesive layer on a release sheet, the adhesive composition can be directly applied on the release sheet using a known coating method, and then the solvent can be evaporated from the coating film by heat drying to form the adhesive layer.

Furthermore, the adhesive (adhesive composition) may be directly applied to one side of the substrate to form an adhesive layer. Examples of the adhesive application method include spin coating, spray coating, rod coating, scraper coating, roller coating, blade coating, die coating, and gravure coating.

[Manufacturing method of semiconductor device] The adhesive tape 10 of the present invention is particularly suitable for use as a back grinding tape attached to the wafer electrical surface when the back surface of the semiconductor wafer is ground while protecting the semiconductor wafer electrical surface in the pre-cutting method. The non-limiting use example of the back grinding tape is described in more detail using the manufacturing of semiconductor devices as an example.

Specifically, the method for manufacturing a semiconductor device includes at least the following steps 1 to 4. Step 1: forming grooves from the surface side of the semiconductor wafer; Step 2: attaching the above-mentioned adhesive tape 10 (back grinding tape) to the surface of the semiconductor wafer; Step 3: grinding the semiconductor wafer with the adhesive tape 10 attached to the surface and the above-mentioned grooves formed thereon from the back side and removing the bottom of the grooves to singulate into a plurality of chips (chip group 20) (refer to FIG. 1); and Step 4: transferring the chip group 20 to the pick-up tape 30 or the connecting tape (refer to FIG. 2 to FIG. 5), and peeling each chip from the pick-up tape or the connecting tape.

The following describes in detail each step of the method for manufacturing the semiconductor device. (Step 1) In step 1, a groove is formed from the surface side of the semiconductor wafer. The groove formed in this step is a groove having a depth shallower than the thickness of the semiconductor wafer. The formation of the groove can be performed by cutting using a previously known wafer cutting device or the like. In addition, the semiconductor wafer is divided into a plurality of semiconductor chips along the groove by removing the bottom of the groove in step 3 described later.

The semiconductor wafer used in this manufacturing method can be a silicon wafer, and can also be a wafer of gallium and arsenic, a glass wafer, a sapphire wafer, etc. The thickness of the semiconductor wafer before grinding is not particularly limited, and is usually about 500 to 1000 μm. In addition, the semiconductor wafer usually has a circuit formed on its surface. The circuit can be formed on the surface of the wafer by various methods including etching, lift-off method and other previously widely used methods.

(Step 2) In step 2, the adhesive tape 10 of the present invention is attached to the surface of the semiconductor wafer having the grooves formed thereon via the adhesive layer.

(Step 3) After Step 1 and Step 2, the back side of the semiconductor wafer on the adsorption machine is ground and the semiconductor wafer is singulated into a plurality of semiconductor chips. Here, when the semiconductor wafer has a groove formed therein, the back side grinding is performed to thin the semiconductor wafer to at least the bottom of the groove. By this back side grinding, the groove becomes a cut that passes through the wafer, and the semiconductor wafer is divided by the cut and singulated into individual semiconductor chips.

The shape of the semiconductor wafers cut into pieces may be square or rectangular. The thickness of the semiconductor wafers cut into pieces is not particularly limited, but is preferably about 5 to 100 μm, more preferably 10 to 45 μm. The size of the semiconductor wafers cut into pieces is not particularly limited, but is preferably less than 200 mm ² , more preferably less than 150 mm ² , and more preferably less than 120 mm ² .

After the above steps, a wafer group 20 can be obtained on the adhesive tape (back grinding tape) 10 as shown in Fig. 1. In addition, after the back grinding is completed, dry polishing can also be performed before the wafer is picked up.

(Step 4) Next, the singulated chip group 20 is transferred from the back grinding tape to the pick-up tape 30 or the connecting tape, and each chip 21 is peeled off from the pick-up tape or the connecting tape. This step is explained below based on the example of using the pick-up tape.

First, the adhesive layer 12 of the adhesive tape 10 is irradiated with energy rays to harden the adhesive layer. Next, the pick-up tape 30 is attached to the back side of the chip group 20 (FIG. 2) to align the position and direction in a manner that allows pickup. At this time, the annular frame 40 disposed on the outer peripheral side of the chip group 20 is also attached to the pick-up tape 30, and the outer peripheral portion of the pick-up tape 30 is fixed to the annular frame 40. The pick-up tape 30 can be attached to the chip group 20 and the annular frame 40 at the same time, and can also be attached according to separate timings. Next, only the back grinding tape 10 is peeled off and the chip group 20 is transferred to the pick-up tape.

When the back grinding tape 10 is peeled, the peeling tape 50, which is the starting point of the peeling, is fixed to the back side (substrate side) of the back grinding tape 10 (Figure 3). The back grinding tape is roughly the same shape as the semiconductor wafer, and since there is no starting point for the peeling, the thin rectangular peeling tape 50 is fixed as the starting point for the peeling. The peeling tape 50 is strongly fixed to the back side of the back grinding tape 10 by heat pressing. The peeling of the back grinding tape 10 is shown in Figures 4 and 5. It is better to peel with the peeling tape 50 as the starting point and fold the back grinding tape 10 back.

Then, the pick-up tape 30 is expanded and the chips are separated as needed, and each semiconductor chip 21 on the pick-up tape 30 is picked up and fixed on a substrate or the like to manufacture a semiconductor device.

In addition, the pick-up tape 30 is not particularly limited, and can be composed of, for example, an adhesive tape called a dicing tape having a base material and an adhesive layer provided on one side of the base material. The adhesive force of the pick-up tape 30 can be greater than the adhesive force of the back grinding tape 30 when peeled off. In addition, it is preferable to have a property that can reduce the adhesive force when the wafer 21 is peeled off from the pick-up tape 30. Therefore, as the pick-up tape, an energy ray-hardening adhesive tape can be suitably used.

Furthermore, a bonding tape can be used instead of a pickup tape. The bonding tape includes a laminate of a film adhesive and a peeling sheet, a laminate of a dicing tape and a film adhesive, a dicing and die bonding tape composed of an adhesive layer and a peeling sheet having the functions of both a dicing tape and a die bonding tape, and the like. Furthermore, before attaching the pickup tape, a film adhesive can be attached to the back side of the singulated semiconductor wafer. When a film adhesive is used, the film adhesive can also be in the same shape as the wafer.

When using adhesive tape, or when a film adhesive is applied to the back side of a singulated semiconductor wafer before attaching a pick-up tape, etc., a plurality of semiconductor chips on the adhesive tape, pick-up tape, etc. are picked up together with the adhesive layer separated into the same shape. Then, the semiconductor chip is fixed on the upper surface of a substrate, etc. through the adhesive layer to manufacture a semiconductor device. The separation of the adhesive layer can be performed using laser and expansion.

Furthermore, the peeling tape 50 is not particularly limited as long as it can be firmly heat-sealed to the back of the substrate of the adhesive tape 10. Therefore, the peeling tape 50 can be appropriately selected in consideration of the material of the substrate 11 of the adhesive tape 10. In the present invention, the substrate 11 is preferably made of a polyester film such as polyethylene terephthalate. Therefore, the peeling tape 50 can be suitably used as a polyolefin tape having good heat-sealing properties with a polyester film. Examples of such polyolefin tapes include polyethylene tapes, polypropylene tapes, etc., but the present invention is not limited thereto.

The peeling tape 50 is cut into a thin rectangular shape, and although not limited to this shape, the width is usually about 50 mm and the length is about 60 mm. The thickness of the peeling tape 50 may be about 10 to 150 μm.

When the peeling tape 50 is fixed to the back side (substrate 11) of the adhesive tape 10, the two can be firmly heat-sealed by hot pressing. The hot pressing conditions vary depending on the material of the substrate 11 and the material of the peeling tape 50. Usually, hot pressing is performed for about 0.5 to 10 seconds under the conditions of a pressure of about 0.2 to ¹ N/cm2 and a temperature of about 120 to 250°C. In addition, during hot pressing, the peeling tape 50 is provided with a heat-sealed portion on the substrate 11 in an area that can be sufficiently fixed. For example, it is preferable to set the heat-sealed portion in an area of about 0.1 to 3 mm from the outer edge of the substrate 11 toward the center of the substrate 11.

As described above, when the peeling tape 50 is heat-pressed to the back side (substrate 11) of the adhesive tape 10, heat and pressure are also transmitted to the adhesive layer 12 of the adhesive tape 10, and the chip 21 is heat-pressed to the adhesive layer 12. When the storage elastic modulus of the adhesive is reduced due to the heating during the heat-pressing, the chip 21 is buried in the adhesive layer, and when the adhesive tape 10 is peeled off, the chip may be peeled off together with the adhesive tape 10, resulting in poor chip transfer. However, in the present invention, the adhesive has a storage elastic modulus _E'200 after curing within the above range, and will not be excessively softened even under hot pressing conditions. Therefore, the chip is prevented from being buried in the adhesive layer, and chip transfer failure can be reduced.

Furthermore, as mentioned above, a highly cross-linked structure is formed in the adhesive layer after curing. Therefore, a photopolymerization initiator having a high energy-beam-polymerizable unsaturated base density and a large amount is added to the adhesive layer before curing. Therefore, even if the amount of energy beam irradiated is relatively small, the storage elastic modulus of the adhesive after curing can be sufficiently improved. Usually, the adhesive tape is heated by energy beam irradiation, which may cause deformation of the adhesive tape and poor chip transfer. However, according to the present invention, the amount of energy beam irradiation can be reduced. Therefore, deformation of the adhesive tape caused by heat during irradiation can be suppressed, and the poor chip transfer caused by this can also be suppressed.

The above mainly describes the example of using the adhesive tape of the present invention in a method of singulating semiconductor wafers by a pre-cutting method. The adhesive tape of the present invention can also be used in normal back grinding, and can also be used to temporarily fix the workpiece when processing glass, ceramics, etc. In addition, it can also be used as various re-peeling adhesive tapes. Examples

The present invention is described in more detail below based on examples, but the present invention is not limited to these examples. The measurement method and evaluation method of the present invention are as follows.

[Storage elastic modulus after curing] The adhesive composition prepared in the embodiment and the comparative example was applied to a peeling sheet (SP-PET3801 manufactured by LINTEC, thickness: 38 μm) obtained by peeling one side of a polyethylene terephthalate film using a silicone-based peeling agent and dried to produce an adhesive layer with a thickness of 20 μm. The obtained adhesive layer was stacked in multiple layers in such a way that the thickness became 3 mm. A cylinder with a diameter of 8 mm (height 3 mm) was punched out from the laminate of the obtained adhesive layer and used as a sample. The sample was irradiated with ultraviolet rays and the adhesive layer was completely cured. The above-mentioned ultraviolet irradiation conditions are: wavelength 365nm, illuminance 150mW/ ^cm2 , and light quantity 300mJ/ ^cm2 .

The storage elastic modulus E' of the hardened samples was measured at a frequency of 11 Hz and a temperature of 200°C using a dynamic viscoelasticity device (manufactured by ORIENTEC, trade name "Rheovibron DDV-11-EP1") for 10 samples.

[Adhesion after hot pressing] The adhesive tape with the peeling sheet obtained in the embodiment and the comparative example was mounted on a tape laminating machine (manufactured by LINTEC Co., Ltd., trade name "RAD-3510F/12") while peeling off the peeling sheet, and was attached to the polished surface of a bare wafer (diameter 12 inches, thickness 740μm, #2000 polishing). Subsequently, the outer periphery of the adhesive tape was cut off to obtain the same shape as the bare wafer.

Then, using a chip mounter with UV irradiation and tape peeling device (manufactured by LINTEC Co., Ltd., trade name "RAD-2700"), UV rays are irradiated from the substrate side of the adhesive tape to completely cure the adhesive layer. The UV irradiation conditions are wavelength 365nm, illumination 150mW/ ^cm2 , and light intensity 300mJ/ ^cm2 . Next, a dicing tape (manufactured by LINTEC Co., Ltd., Adwill ID-175) is attached to the other side of the bare wafer as a pickup tape. Next, a polypropylene film (manufactured by LINTEC Co., Ltd., Adwill S-750) with a width of 50mm and a length of 60mm is prepared as a peeling tape. Heat sealing was performed for 5 seconds using a heat sealing device at a pressure of 0.5 N/cm ² and a temperature of 210°C, and a peeling tape was heat-pressed onto the outer edge of the adhesive tape. The heat-sealed portion was set to be an area 2 mm from the outer edge of the adhesive tape toward the center.

Use a tensile tester (manufactured by Shimadzu Corporation, AUTOGRAPH AG-IS) to peel the adhesive tape from the bare wafer at a peeling speed of 300 mm/min and a peeling angle of 180°. Measure the maximum peeling force from the start of peeling to the complete peeling of the heat-sealed part (approximately 1 cm). Measure the maximum peeling force for 10 pieces of adhesive tape. The average value is taken as the adhesive force after hot pressing.

[Peeling evaluation] On the polished surface of the bare wafer, which is the same as the measurement of adhesion after hot pressing, grooves with a depth of 70μm and a width of 30μm were cut at 1mm intervals in the longitudinal and lateral directions of the wafer, and adhesive tape (back grinding tape) was attached to the same surface. Subsequently, the back side of the wafer was ground and singulated using the pre-cutting method into wafers with a thickness of 30μm and a chip size of 1mm×1mm.

After the back grinding is completed, a chip mounter with UV irradiation and tape peeling device (manufactured by LINTEC Co., Ltd., trade name "RAD-2700") is used to irradiate UV rays from the substrate side of the adhesive tape and completely cure the adhesive layer. The UV irradiation conditions are as follows: wavelength 365nm, illumination 150mW/ ^cm2 , light quantity 300mJ/ ^cm2 . Subsequently, a dicing tape (manufactured by LINTEC Co., Ltd., Adwill D-175) is used as a pick-up tape and attached to the chip group, and the outer periphery of the dicing tape is fixed with a ring frame. Next, a polypropylene film (manufactured by LINTEC Co., Ltd., Adwill S-750) with a width of 50mm and a length of 60mm is prepared as a peeling tape. Heat sealing was performed for 5 seconds using a heat sealing device at a pressure of 0.5 N/cm ² and a temperature of 210°C, and a peeling tape was heat-pressed onto the outer edge of the adhesive tape. The heat-sealed portion was set to be an area 2 mm from the outer edge of the adhesive tape toward the center.

Hold the peeling tape, fold the adhesive tape back, and peel the chip group from the adhesive tape. Check the number of chips remaining on the adhesive layer of the adhesive tape. Total the number of chips remaining on the adhesive tape in the above operation and evaluate based on the following criteria. Excellent: less than 10 Good: more than 10 and less than 30 Bad: more than 30

In addition, all the mass values of the following Examples and Comparative Examples are solid content values.

Composite substrate Polyethylene terephthalate (PET) film is used as the substrate. A composite substrate with the following buffer layer provided on the substrate is prepared. The buffer layer is made of low-density polyethylene (LDPE) with a thickness of 27.5μm. Composite substrate 1: LDPE (27.5μm)/PET (25.0μm)/LDPE (27.5μm) Composite substrate 2: LDPE (27.5μm)/PET (50μm)/LDPE (27.5μm) Composite substrate 3: LDPE (27.5μm)/PET (75.0μm)/LDPE (27.5μm)

Adhesive layer The following adhesive compositions A to D were prepared. (Preparation of adhesive composition A) An acrylic polymer (Mw: 800,000) was obtained by copolymerizing 89 parts by mass of butyl acrylate (BA), 8 parts by mass of methyl methacrylate (MMA), and 3 parts by mass of 2-hydroxyethyl acrylate (2HEA).

With respect to 100 parts by mass of the energy-ray-curable acrylic polymer, 1 part by mass (solid content) of a toluene diisocyanate crosslinking agent (manufactured by TOSOH, product name "CORONATE L"), 2 parts by mass (solid content) of an epoxy crosslinking agent (1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane), 45 parts by mass (solid content) of an ultraviolet-curable resin (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., product name "Ultraviolet UV-3210EA"), and 3.5 parts by mass (solid ratio) of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals Co., Ltd., product name "IRGACURE 184") were mixed to obtain an energy-ray-curable adhesive composition A. The obtained adhesive composition was used to measure the storage elastic modulus after curing.

(Preparation of adhesive composition B) An acrylic polymer obtained by copolymerizing 50 parts by mass of butyl acrylate (BA), 25 parts by mass of methyl methacrylate (MMA), and 25 parts by mass of 2-hydroxyethyl acrylate (2HEA) was reacted with 2-methylpropionyloxyethyl isocyanate (MOI) in such a manner that 90 mol% of hydroxyl groups in the total hydroxyl groups of the acrylic polymer were added to obtain an energy ray-curable acrylic resin (Mw: 500,000).

With respect to 100 parts by mass of the energy ray-curable acrylic polymer, 6 parts by mass of urethane acrylate oligomer (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name "UT-4220") as an energy ray-curable compound, 1 part by mass of toluene diisocyanate crosslinking agent (manufactured by TOSOH, product name "CORONATE"), and 1.16 parts by mass of photopolymerization initiator (manufactured by Ciba Specialty Chemicals, IRGACURE 184) (solid ratio) were mixed to obtain an energy ray-curable adhesive composition B. The obtained adhesive composition was used to measure the storage elastic modulus after curing.

(Preparation of adhesive composition C) An acrylic polymer obtained by copolymerizing 60 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 20 parts by mass of 2-hydroxyethyl acrylate (2HEA) was reacted with 2-methylpropionyloxyethyl isocyanate (MOI) in such a manner that 80 mol% of hydroxyl groups were added to the total hydroxyl groups of the acrylic polymer to obtain an energy ray-curable acrylic resin (Mw: 450,000).

With respect to 100 parts by mass of the energy ray-curable acrylic polymer, 0.7 parts by mass (solid content) of a toluene diisocyanate crosslinking agent (manufactured by TOSOH, trade name "CORONATE") and 1.16 parts by mass (solid ratio) of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, IRGACURE 184) were mixed to obtain an energy ray-curable adhesive composition C. The obtained adhesive composition was used to measure the storage elastic modulus after curing.

(Preparation of adhesive composition D) 89 parts by mass of butyl acrylate (BA), 8 parts by mass of methyl methacrylate (MMA), and 3 parts by mass of 2-hydroxyethyl acrylate (2HEA) were copolymerized to obtain an acrylic polymer (Mw: 800,000).

With respect to 100 parts by mass of the energy ray-curable acrylic polymer, 1 part by mass (solid content) of a toluene diisocyanate crosslinking agent (manufactured by TOSOH, product name "CORONATE L") as a crosslinking agent, 22 parts by mass (solid content) of an ultraviolet-curable resin (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., product name "UV-3210EA"), and 1.16 parts by mass (solid content) of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals Co., Ltd., product name "IRGACURE 184") were mixed to obtain an energy ray-curable adhesive composition D. The obtained adhesive composition was used to measure the storage elastic modulus after curing.

[Example 1] The coating liquid of the energy-beam-curable adhesive composition A obtained above was applied to the peeling-treated surface of a peeling sheet (manufactured by LINTEC, trade name "SP-PET381031"), and dried by heating at 100°C for 1 minute to form an adhesive layer with a thickness of 20 μm on the peeling sheet.

The adhesive layer is laminated to one side of a multi-layer substrate to produce an adhesive tape. The adhesive strength of the resulting adhesive tape after heat-press bonding is measured, and the peeling performance is evaluated.

[Example 2] An adhesive tape was produced in the same manner as in Example 1 except that the composite substrate 2 and the adhesive composition B were used and the thickness of the adhesive layer was set to 20 μm. The adhesive force of the obtained adhesive tape after hot pressing was measured and the peeling evaluation was performed.

[Example 3] An adhesive tape was produced in the same manner as in Example 1 except that the composite substrate 3 and the adhesive composition C were used and the thickness of the adhesive layer was set to 40 μm. The adhesive force of the obtained adhesive tape after hot pressing was measured and the peeling evaluation was performed.

[Comparison Example 1] The adhesive tape was produced in the same manner as in Example 1 except that the composite substrate 2 and the adhesive composition D were used and the thickness of the adhesive layer was set to 20 μm. The adhesive force after hot pressing of the obtained adhesive tape was measured and the peeling evaluation was performed. [Table 1]

From the above results, it is known that when the storage elastic modulus _E'200 after curing is 1.5 MPa or more, even if the peeling tape is hot-pressed, the chip transfer at the heat-sealed portion is not defective and the chip can be well transferred to the pickup tape or the connecting tape. In addition, according to the test using the adhesive tape described in detail in the embodiment and the comparative example, and various adhesive tapes, it can be confirmed that when _E'200 is 1.5 MPa or more, good results can be obtained.

10‧‧‧Adhesive tape (back grinding tape) 11‧‧‧Substrate 12‧‧‧Adhesive layer 20‧‧‧Chip group 21‧‧‧Chip 30‧‧‧Pick-up tape 40‧‧‧Ring frame 50‧‧‧Stripping tape

FIG. 1 shows a state where a chip group 20 is obtained on a back grinding tape 10 using a pre-cutting method. FIG. 2 shows a step of transferring the chip group 20 from the back grinding tape 10 to the pickup tape 30. FIG. 3 shows a state where a peeling tape 50 is heat-pressed and bonded to the back of the back grinding tape 10. FIG. 4 shows a state where the back grinding tape 10 is peeled off using the peeling tape 50 as a starting point. FIG. 5 shows an oblique view of FIG. 4.

10‧‧‧Adhesive tape (back grinding tape)

20‧‧‧Chip Group

21‧‧‧Chip

30‧‧‧Pick up the tape

40‧‧‧Ring frame

50‧‧‧Peeling tape

Claims (3)

An adhesive tape, which includes a back grinding tape attached to the surface of a semiconductor wafer having grooves formed thereon, and the back side is ground and the semiconductor wafer is singulated into semiconductor chips by the grinding, and then the singulated chip group is attached to a pickup tape or a connecting tape, and a peeling tape which is the start of peeling is hot-pressed to the back side of the back grinding tape, and the back grinding tape is peeled off by using the peeling tape as the starting point. , used as the aforementioned back grinding tape in a method for manufacturing a semiconductor device in the step of transferring a singulated chip group to a pickup tape or a connecting tape; and is an adhesive tape comprising a substrate and an adhesive layer disposed on one side of the substrate, wherein: the aforementioned adhesive layer is composed of an energy-ray-curable adhesive; and the storage elastic modulus _E'200 of the adhesive at 200°C after curing by energy-ray irradiation and before hot-pressing with a peeling tape is greater than 1.5 MPa and less than 100 MPa. A method for manufacturing a semiconductor device includes attaching a back grinding tape to a semiconductor wafer surface having grooves formed thereon, grinding the back side and singulating the semiconductor wafer into semiconductor chips by the grinding, then attaching the singulated chip group to a pickup tape or a connecting tape, and hot-pressing a peeling tape as a starting point of peeling to the back side of the back grinding tape, peeling the back grinding tape using the peeling tape as a starting point, and transferring the singulated chip group, and using the adhesive tape described in item 1 of the patent application scope as the aforementioned back grinding tape. A use of an adhesive tape is the use of the adhesive tape as described in item 1 of the patent application scope, in a method for manufacturing a semiconductor device including the steps of attaching a back grinding tape to a semiconductor wafer surface having grooves formed thereon, grinding the back side and singulating the semiconductor wafer into semiconductor chips by the grinding, then attaching the singulated chip group to a pickup tape or a connecting tape, and hot-pressing a peeling tape as a start of peeling to the back side of the back grinding tape, peeling the back grinding tape using the peeling tape as a starting point, and transferring the singulated chip group, the back grinding tape is used as the use of the back grinding tape.