JPWO2019181732A1 - Manufacturing method of adhesive tape and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce transfer failure of a chip 21 from a back grind tape 10 to a pickup tape 30 or an adhesive tape, particularly at the time of manufacturing a micro semiconductor chip adopting a pre-dicing method. Another object of the present invention is to improve the transfer efficiency of the chip from the back grind tape 10 to the pickup tape 30 or the adhesive tape. An adhesive tape 10 according to the present invention is preferably used as the back grind tape, and includes a base material 11 and an adhesive layer 12 provided on one side thereof, and the adhesive layer 12 is an energy ray. It is made of a curable pressure-sensitive adhesive, and after a silicon wafer mirror surface is attached to the pressure-sensitive adhesive layer 12, the pressure-sensitive adhesive layer is cured by irradiating it with energy rays, and further heat-bonded at a pressure of 0.5 N / cm2 and 210 ° C. for 5 seconds. It is characterized in that the adhesive strength at 23 ° C. is 9.0 N / 25 mm or less. [Selection diagram] Fig. 5

Description

The present invention relates to an adhesive tape, and more specifically, an adhesive tape preferably used for temporarily fixing a semiconductor wafer or a chip when manufacturing a semiconductor device by a so-called pre-dicing method, and a semiconductor using the adhesive tape. Regarding the manufacturing method of the device.

As various electronic devices are becoming smaller and more multifunctional, the semiconductor chips mounted on them are also required to be smaller and thinner. In order to reduce the thickness of the chip, it is common to grind the back surface of the semiconductor wafer to adjust the thickness. Further, after forming a groove having a predetermined depth from the front surface side of the wafer, grinding is performed from the back surface side of the wafer, the bottom of the groove is removed by grinding to individualize the wafer, and a method called a pre-dicing method for obtaining chips is performed. It may be used. In the pre-dicing method, the back surface of the wafer can be ground and the wafer can be separated into individual pieces at the same time, so that a thin chip can be efficiently manufactured.

Conventionally, when the back surface of a semiconductor wafer is ground or when a chip is manufactured by a pre-dicing method, a back grind tape is called on the wafer surface in order to protect the circuit on the wafer surface and fix the semiconductor wafer and the semiconductor chip. It is common to attach an adhesive tape.

The chip pickup after the wafer is separated into individual pieces by the pre-dicing method will be described below with reference to the drawings. By the pre-dicing, the semiconductor wafer is fragmented, and a chip group 20 composed of a large number of fragmented chips 21 is obtained on the back grind tape 10 (FIG. 1). The chip group 20 is transferred to an adhesive tape called a pickup tape 30, expanded to expand the chip spacing as necessary, and then peeled off from the pickup tape 30 (Patent Document 1: Japanese Patent Application Laid-Open No. 2012-209385). Gazette). As the pickup tape 30, adhesive tapes called dicing tapes are often used. The transfer of the chip group 20 from the back grind tape 10 to the pickup tape 30 is performed as follows. That is, the pickup tape 30 is attached to the held chip group 20 on the back grind tape 10. At this time, the outer peripheral portion of the pickup tape 30 is fixed by the ring frame 40 (FIG. 2). Then, by peeling off only the back grind tape 10, the chip group 20 is transferred to the pickup tape 30.

The back grind tape 10 needs to have an adhesive force sufficient to stably hold the wafer and the chip group in the back surface grinding process, and can be easily peeled off from the chip surface when the chip group is transferred to the pickup tape 30. It needs to be adhesive. For this reason, an energy ray-curable pressure-sensitive adhesive that can reduce the adhesive force by irradiation with energy rays is often used for the pressure-sensitive adhesive layer 12 of the back grind tape 10. For example, Patent Document 2 (Japanese Unexamined Patent Publication No. 2002-053819) discloses a backgrind tape having an adhesive force of 150 g / 25 mm or more before energy ray curing and an adhesive force of 150 g / 25 mm or less after energy ray curing. Has been done. Here, the adhesive strength is the adhesive strength measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees using a SUS304-BA plate as an adherend in accordance with the method specified in JIS Z-0237. is there.

Further, Patent Document 3 (Japanese Unexamined Patent Publication No. 2016-72546) discloses an adhesive tape for protecting the surface of a semiconductor wafer used in the pre-dicing method. The purpose of this adhesive tape is to suppress calf shift during pre-dicing, to eliminate the transfer of the adhesive to the semiconductor chip and the peeling failure of the semiconductor chip, and the base material of the adhesive tape has a tensile elastic modulus of 1. It is specified that at least one rigid layer of 10 GPa is provided, and the peeling force at a peeling angle of 30 ° after the pressure-sensitive adhesive layer is radiation-cured is 0.1 to 3.0 N / 25 mm.

When the back grind tape 10 is peeled off, the peeling tape 50 that serves as a trigger for peeling is fixed to the back surface (base material surface) of the back grind tape 10 (FIG. 3). Since the back grind tape has substantially the same shape as the semiconductor wafer and does not have a starting point for peeling, the strip-shaped peeling tape 50 is fixed as a starting point for peeling. The peeling tape 50 is firmly fixed to the back surface of the back grind tape 10 by thermocompression bonding.

Japanese Unexamined Patent Publication No. 2012-209385 Japanese Unexamined Patent Publication No. 2002-0538919 Japanese Unexamined Patent Publication No. 2016-72546

When the peeling tape 50 is thermocompression bonded to the back grind tape 10, the peeling tape 50 is heat-sealed on the back surface of the back grind tape 10 by heating to about 140 to 230 ° C. and applying pressure. Therefore, the adhesive layer of the back grind tape located in the heat seal portion is also heated and pressurized. As a result, the pressure-sensitive adhesive layer cured by energy beam irradiation flows and is activated by heating and pressurizing, and the cured pressure-sensitive adhesive layer of the backgrind tape and the chip are thermocompression-bonded. When the back grind tape 10 is peeled off from the peeling tape as a starting point in this state, the back grind tape is peeled off with the chip 21 fixed to the back grind tape 10 in the heat-sealed portion and its vicinity, and the tip is collected. The rate decreases (FIGS. 4 and 5). Hereinafter, this phenomenon may be referred to as "chip transfer failure".

When the chip size was relatively large, the back grind tape and the chip surface were successfully peeled off, but as the chip size became smaller, the chip was more likely to be embedded in the adhesive layer 12 of the back grind tape. As a result, it becomes more difficult to peel the chip from the back grind tape, and transfer defects of the chip increase. Further, in the pre-dicing method, a relatively hard base material is often used as the base material 11 of the back grind tape. Therefore, when the back grind tape is peeled off, the back grind tape cannot be sufficiently folded back, which also makes peeling difficult and causes an increase in transfer defects.

In Patent Document 3, since the base material is hard, it becomes difficult to bend the adhesive tape. Therefore, the peeling angle becomes an acute angle, the peeling force is strong, and it takes time to peel.

Therefore, according to the present invention, particularly when the chip group 20 is transferred from the back grind tape 10 to another tape such as a pickup tape or an adhesive tape during the production of a micro semiconductor chip adopting the pre-dicing method, the chip 21 The purpose is to reduce transfer defects. It is also intended to improve the efficiency of chip transfer from back grind tapes to other tapes such as pickup tapes or adhesive tapes.

The gist of the present invention for solving such a problem is as follows.
(1) An adhesive tape containing a base material and an adhesive layer provided on one side thereof.
The pressure-sensitive adhesive layer comprises an energy ray-curable pressure-sensitive adhesive.
After a silicon wafer mirror surface is attached to the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is cured by irradiating it with energy rays, and further ^{thermocompression-bonded at a pressure of 0.5 N / cm 2} and 210 ° C. for 5 seconds, and the adhesive strength at 23 ° C. is 9. Adhesive tape of 0.0N / 25mm or less.
(2) A back grind tape was attached to the surface of the semiconductor wafer having grooves formed on the surface of the semiconductor wafer, the back surface was ground, and the semiconductor wafer was fragmented into semiconductor chips by the grinding, and then fragmented. The adhesive tape according to (1), which is used as the backgrinding tape in a method for manufacturing a semiconductor device including a step of transferring a group of chips to a pickup tape or an adhesive tape.
(3) A back grind tape was attached to the surface of the semiconductor wafer having grooves formed on the surface of the semiconductor wafer, the back surface was ground, and the semiconductor wafer was fragmented into semiconductor chips by the grinding, and then fragmented. A method for manufacturing a semiconductor device, which comprises a step of transferring a chip group to a pickup tape or an adhesive tape, wherein the adhesive tape according to (1) is used as the backgrinding tape.
(4) In the use of the adhesive tape according to (1) above, a back grind tape is attached to the surface of a semiconductor wafer having grooves formed on the surface of the semiconductor wafer, the back surface is ground, and the semiconductor is ground by the grinding. Use as the backgrinding tape in a method for manufacturing a semiconductor device, which comprises a step of fragmenting a wafer into semiconductor chips and then transferring the fragmented chips to a pickup tape or an adhesive tape.

According to the adhesive tape 10 according to the present invention, even if the peeling tape 50 is thermocompression bonded after the energy ray-curable pressure-sensitive adhesive layer is cured, the adhesive strength between the adherend (semiconductor chip) and the adhesive tape is extremely strong. By suppressing the level to a low level, it is possible to prevent poor transfer of the chip.

A state in which the chip group 20 is obtained on the back grind tape 10 by the pre-dicing method is shown. The process of transferring the chip group 20 from the back grind tape 10 to the pickup tape 30 is shown. A state in which the peeling tape 50 is thermocompression bonded to the back surface of the back grind tape 10 is shown. The state in which the background tape 10 is peeled off from the peeling tape 50 as a starting point is shown. The perspective view of FIG. 4 is shown.

Hereinafter, the adhesive tape according to the present invention will be specifically described. First, the main terms used in the present specification will be described.
In the present specification, for example, "(meth) acrylate" is used as a term indicating both "acrylate" and "methacrylate", and the same applies to other similar terms.

The adhesive tape means a laminate including a base material and an adhesive layer provided on one side thereof, and does not prevent the inclusion of other constituent layers other than these. For example, a primer layer (easy-adhesive layer) may be formed on the surface of the base material on the pressure-sensitive adhesive layer side, and a release sheet for protecting the pressure-sensitive adhesive layer is laminated on the surface of the pressure-sensitive adhesive layer. It may have been done. Further, the base material may be a single layer or may be a multilayer having a functional layer such as a buffer layer. The same applies to the pressure-sensitive adhesive layer.
The "front surface" of the semiconductor wafer refers to the surface on which the circuit is formed, and the "back surface" refers to the surface on which the circuit is not formed.
Fragmentation of a semiconductor wafer means dividing a semiconductor wafer into circuits to obtain a semiconductor chip.

The silicon bare wafer is a silicon wafer in a state before processing such as pattern formation, and its surface is mirror-polished.
The pre-dicing method is a method in which a groove having a predetermined depth is formed from the front surface side of the wafer, then grinding is performed from the back surface side of the wafer, and the wafer is separated by grinding.

The back grind tape is an adhesive tape used to protect the wafer circuit surface when grinding the back surface of a semiconductor wafer, and particularly, in this specification, refers to an adhesive tape preferably used in a pre-dicing method.
The pickup tape is an adhesive tape for transferring a group of chips and picking up the chips, and typically, adhesive tapes called dicing tapes are used.
Adhesive tape means various tapes that have a thin layer that functions as an adhesive and are used to transfer the adhesive layer to another adherend. Specifically, from a laminate of a film-like adhesive and a release sheet, a laminate of a dicing tape and a film-like adhesive, and an adhesive layer and a release sheet having the functions of both a dicing tape and a die bonding tape. Examples include dicing and die bonding tapes.

The adhesive tape according to the present invention is particularly preferably used as the back grind tape. The adhesive tape 10 according to the present invention includes a base material 11 and an adhesive layer 12 provided on one side thereof. Hereinafter, the configuration of each member of the adhesive tape 10 of the present invention will be described in more detail.
[Base material 11]
As the base material 11 of the adhesive tape 10, various resin films used as the base material of the back grind tape are used.

An example of the base material 11 used in the present invention will be described in detail below, but these are merely descriptions for facilitating the acquisition of the base material and should not be construed in any limited way.

The base material of the present invention may be, for example, a relatively hard resin film. Further, a buffer layer made of a relatively soft resin film may be laminated on one side or both sides of the base material.

A preferred substrate has a Young's modulus of 1000 MPa or more. If a base material having 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 deteriorates, vibration during backside grinding cannot be suppressed, and the semiconductor chip is chipped or damaged. It will be easier. On the other hand, by setting the Young's modulus of the base material to 1000 MPa or more, the holding performance of the adhesive tape on the semiconductor wafer or the semiconductor chip is enhanced, vibration or the like during backside grinding can be suppressed, and chipping or breakage of the semiconductor chip can be prevented. In addition, the stress when the adhesive tape is peeled from the semiconductor chip can be reduced, and the chip chipping or breakage that occurs when the tape is peeled can be prevented. Further, it is possible to improve the workability when the adhesive tape is attached to the semiconductor wafer. From this point of view, the Young's modulus of the base material is preferably 1800 to 30000 MPa, more preferably 2500 to 6000 MPa.

The thickness (D1) of the base material 11 is not particularly limited, but is preferably 500 μm or less, more preferably 15 to 350 μm, and further preferably 20 to 160 μm. By setting the thickness of the base material to 500 μm or less, it becomes easy to control the peeling force of the adhesive tape. Further, when the thickness is 15 μm or more, the base material easily functions as a support for the adhesive tape.

As the material of the base material 11, various resin films can be used. Here, as a base material having a Young ratio of 1000 MPa or more, for example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and total aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sulfide, and polysulfone, Examples thereof include resin films such as polyether ketone and biaxially stretched polypropylene.
Among these resin films, a film containing at least one selected from a polyester film, a polyamide film, a polyimide film, and a biaxially stretched polypropylene film is preferable, a polyester film is more preferable, and a polyethylene terephthalate film is further preferable. ..

Further, the base material may contain a plasticizer, a lubricant, an infrared absorber, an ultraviolet absorber, a filler, a colorant, an antistatic agent, an antioxidant, a catalyst, etc., as long as the effects of the present invention are not impaired. Good. In addition, the base material has transparency to the energy rays emitted when the pressure-sensitive adhesive layer is cured.
Further, the surface of at least one of the base materials may be subjected to an adhesive treatment such as a corona treatment in order to improve the adhesion with at least one of the buffer layer and the pressure-sensitive adhesive layer. Further, the base material may have the above-mentioned resin film and an easy-adhesion layer (primer layer) coated on at least one surface of the resin film.

The composition for forming the easy-adhesive layer for forming the easy-adhesive layer is not particularly limited, and examples thereof include compositions containing a polyester resin, a urethane resin, a polyester urethane resin, an acrylic resin, and the like. The composition for forming an easy-adhesive layer may contain a cross-linking agent, a photopolymerization initiator, an antioxidant, a softening agent (plasticizer), a filler, a rust preventive, a pigment, a dye, etc., if necessary. Good.
The thickness of the easy-adhesion layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm. Since the thickness of the easy-adhesion layer is small with respect to the thickness of the base material and the material is soft, the influence on the Young's modulus is small, and the Young's modulus of the base material is the resin film even when the easy-adhesion layer is provided. It is substantially the same as Young's modulus of.

[Cushioning layer]
A buffer layer may be provided on one side or both sides of the base material 11. The cushioning layer is made of a relatively soft resin film, which alleviates vibration caused by grinding the semiconductor wafer and prevents the semiconductor wafer from cracking and chipping. Further, the semiconductor wafer to which the adhesive tape is attached is placed on the suction table at the time of backside grinding, but the adhesive tape is easily held on the suction table by providing the cushioning layer.

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

The buffer layer includes polypropylene film, ethylene-vinyl acetate copolymer film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene (meth) acrylic acid ester copolymer film, LDPE film, and LLDPE film. preferable. Further, it may be a layer formed from a composition for forming a buffer layer containing an energy ray-polymerizable compound. The base material having a buffer layer is obtained by laminating the base material and the above film. Further, it is also a preferable embodiment that a composition for forming a buffer layer containing an energy ray-polymerizable compound is applied onto the base material and cured to form a buffer layer. The composition for forming a buffer layer containing an energy ray-polymerizable compound contains the energy ray-polymerizable compound and is cured by being irradiated with energy rays to form a buffer layer. The "energy ray" refers to ultraviolet rays, electron beams, etc., and preferably ultraviolet rays are used.

More specifically, the composition for forming a buffer layer contains urethane (meth) acrylate (a1) and a polymerizable compound (a2) having an alicyclic group or a heterocyclic group having 6 to 20 ring-forming atoms. Is preferable. It is more preferable that the composition for forming a buffer layer contains a polymerizable compound (a3) having a functional group in addition to the above components (a1) and (a2).
Further, the composition for forming a buffer layer preferably contains a photopolymerization initiator in addition to the above components (a1) and (a2) or (a1) to (a3), and does not impair the effects of the present invention. In the range, other additives and resin components may be contained.
Hereinafter, each component contained in the composition for forming a buffer layer will be described in detail.

(Urethane (meth) acrylate (a1))
The urethane (meth) acrylate (a1) is a compound having at least a (meth) acryloyl group and a urethane bond, and has a property of being polymerized and cured by irradiation with energy rays. Urethane (meth) acrylate (a1) is an oligomer or polymer.

The mass average molecular weight (Mw) of the component (a1) is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, and even more preferably 3,000 to 20,000. The mass average molecular weight (Mw) is a polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method, and is specifically measured under the following conditions.
(Measurement condition)
-Column: "TSK guard colon HXL-H""TSK gel GMHXL (x2)""TSK gel G2000HXL" (all manufactured by Tosoh Corporation)
-Column temperature: 40 ° C
・ Developing solvent: tetrahydrofuran ・ Flow rate: 1.0 mL / min
The number of (meth) acryloyl groups (hereinafter, also referred to as “functional number”) in the component (a1) may be monofunctional, bifunctional, or trifunctional or higher, but is preferably monofunctional or bifunctional. ..
The component (a1) can be obtained, for example, by reacting a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound with a polyhydric isocyanate compound with a (meth) acrylate having a hydroxyl group. The component (a1) may be used alone or in combination of two or more.

The polyol compound used as a raw material for the component (a1) is not particularly limited as long as it is a compound having two or more hydroxy groups. Specific examples of the polyol compound include alkylene diols, polyether-type polyols, polyester-type polyols, and polycarbonate-type polyols. Among these, polyester type polyol is preferable.
The polyol compound may be any of a bifunctional diol, a trifunctional triol, and a tetrafunctional or higher functional polyol, but a bifunctional diol is preferable, and a polyester type diol is more preferable.

Examples of the polyisocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; isophorone diisocyanate, norbornan diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and dicyclohexylmethane-2. , 4'-diisocyanate, ω, ω'-diisocyanate Diisocyanate diisocyanates such as dimethylcyclohexane; 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, trizine diisocyanate, tetramethylene xylylene diisocyanate, naphthalene- Examples thereof include aromatic diisocyanates such as 1,5-diisocyanate.
Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferable.

Urethane (meth) acrylate (a1) can be obtained by reacting a (meth) acrylate having a hydroxy group with a terminal isocyanate urethane prepolymer obtained by reacting the above-mentioned polyol compound with a polyhydric isocyanate compound. The (meth) acrylate having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group and a (meth) acryloyl group in at least one molecule.

Examples of the (meth) acrylate having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, and 5 -Hydroxycyclooctyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate and other hydroxyalkyl (Meta) acrylate; Hydroxyl group-containing (meth) acrylamide such as N-methylol (meth) acrylamide; Reactant obtained by reacting diglycidyl ester of vinyl alcohol, vinylphenol, bisphenol A with (meth) acrylic acid, etc. Can be mentioned.
Among these, hydroxyalkyl (meth) acrylate is preferable, and 2-hydroxyethyl (meth) acrylate is more preferable.

The conditions for reacting the terminal isocyanate urethane prepolymer and the (meth) acrylate having a hydroxy group are preferably conditions of reacting at 60 to 100 ° C. for 1 to 4 hours in the presence of a solvent and a catalyst added as necessary. ..
The content of the component (a1) in the buffer layer forming composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, based on the total amount (100% by mass) of the buffer layer forming composition. , More preferably 25 to 55% by mass, and even more preferably 30 to 50% by mass.

(Polymeric compound (a2) having an alicyclic group or a heterocyclic group having 6 to 20 ring-forming atoms)
The component (a2) is a polymerizable compound having an alicyclic group or a heterocyclic group having 6 to 20 ring-forming atoms, and is preferably a compound having at least one (meth) acryloyl group. By using this component (a2), the film forming property of the obtained buffer layer forming composition can be improved.

The number of ring-forming atoms of the alicyclic group or the heterocyclic group contained in the component (a2) is preferably 6 to 20, more preferably 6 to 18, still more preferably 6 to 16, and particularly preferably 7 to 12. is there. Examples of the atom forming the ring structure of the heterocyclic group include a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom and the like.
The number of ring-forming atoms represents the number of atoms constituting the ring itself of a compound having a structure in which atoms are cyclically bonded, and atoms not forming a ring (for example, hydrogen atoms bonded to atoms constituting the ring). Or, the atoms included in the substituent when the ring is substituted by the substituent are not included in the number of ring-forming atoms.

Specific components (a2) include, for example, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, and the like. Alicyclic group-containing (meth) acrylates such as adamantan (meth) acrylate; heterocyclic group-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate and morpholin (meth) acrylate; and the like can be mentioned.
The component (a2) may be used alone or in combination of two or more.
Among these, alicyclic group-containing (meth) acrylate is preferable, and isobornyl (meth) acrylate is more preferable.

The content of the component (a2) in the buffer layer forming composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, based on the total amount (100% by mass) of the buffer layer forming composition. , More preferably 25 to 55% by mass, and particularly preferably 30 to 50% by mass.

(Polymerizable compound having a functional group (a3))
The component (a3) is a polymerizable compound containing a functional group such as a hydroxyl group, an epoxy group, an amide group, and an amino group, and more preferably a compound having at least one (meth) acryloyl group.
The component (a3) has good compatibility with the component (a1), and makes it easy to adjust the viscosity of the buffer layer forming composition to an appropriate range. Further, when the component (a3) is contained, the buffering performance is improved even if the buffering layer is made relatively thin.
Examples of the component (a3) include a hydroxyl group-containing (meth) acrylate, an epoxy group-containing compound, an amide group-containing compound, and an amino group-containing (meth) acrylate.

Examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxy. Examples thereof include butyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and phenylhydroxypropyl (meth) acrylate.
Examples of the epoxy group-containing compound include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether, and among these, epoxy such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate. Group-containing (meth) acrylates are preferred.
Examples of the amide group-containing compound include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, and N. Examples thereof include -methoxymethyl (meth) acrylamide and N-butoxymethyl (meth) acrylamide.
Examples of the amino group-containing (meth) acrylate include a primary amino group-containing (meth) acrylate, a secondary amino group-containing (meth) acrylate, and a tertiary amino group-containing (meth) acrylate.

Among these, a hydroxyl group-containing (meth) acrylate is preferable, and a hydroxyl group-containing (meth) acrylate having an aromatic ring such as phenylhydroxypropyl (meth) acrylate is more preferable.
The component (a3) may be used alone or in combination of two or more.

The content of the component (a3) in the buffer layer forming composition is based on the total amount (100% by mass) of the buffer layer forming composition in order to improve the film forming property of the buffer layer forming composition. It is preferably 5 to 40% by mass, more preferably 7 to 35% by mass, still more preferably 10 to 30% by mass, and particularly preferably 13 to 25% by mass.
The content ratio [(a2) / (a3)] of the component (a2) to the component (a3) in the buffer layer forming composition is preferably 0.5 to 3.0, more preferably 1. It is 0 to 3.0, more preferably 1.3 to 3.0, and particularly preferably 1.5 to 2.8.

(Polymerizable compounds other than components (a1) to (a3))
The composition for forming a buffer layer may contain other polymerizable compounds other than the above-mentioned components (a1) to (a3) as long as the effects of the present invention are not impaired.
Other polymerizable compounds include, for example, alkyl (meth) acrylates having an alkyl group having 1 to 20 carbon atoms; styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, N-vinylcaprolactam. Vinyl compounds such as: and the like. In addition, these other polymerizable compounds may be used alone or in combination of 2 or more types.

The content of the other polymerizable compound in the buffer layer forming composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, and particularly preferably 0 to 2. It is mass%.

(Photopolymerization initiator)
The composition for forming a buffer layer preferably further contains a photopolymerization initiator from the viewpoint of shortening the polymerization time by light irradiation and reducing the amount of light irradiation when forming the buffer layer.
Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphinoxide compounds, titanosen compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. Specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfate, etc. Examples thereof include tetramethylthiuram monosulfide, azobisisobutyrolnitrile, dibenzyl, diacetyl, 8-chloranthraquinone, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide and the like.
These photopolymerization initiators can be used alone or in combination of two or more.
The content of the photopolymerization initiator in the buffer layer forming composition is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the energy ray-polymerizable compound. It is by mass, more preferably 0.3 to 5 parts by mass.

(Other additives)
The composition for forming a buffer layer may contain other additives as long as the effects of the present invention are not impaired. Examples of other additives include antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes and the like. When these additives are blended, the content of each additive in the buffer layer forming composition is preferably 0.01 to 6 parts by mass with respect to 100 parts by mass of the total amount of the energy ray-polymerizable compound. More preferably, it is 0.1 to 3 parts by mass.

(Resin component)
The composition for forming a buffer layer may contain a resin component as long as the effects of the present invention are not impaired. Examples of the resin component include polyene-thiol-based resins, polyolefin-based resins such as polybutene, polybutadiene, and polymethylpentene, and thermoplastic resins such as styrene-based copolymers.
The content of these resin components in the composition for forming a buffer layer is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, and particularly preferably 0 to 2% by mass. %.

[Adhesive layer 12]
The pressure-sensitive adhesive layer 12 is formed on one surface of the base material 11 directly or via a buffer layer. In the present invention, the pressure-sensitive adhesive layer is made of an energy ray-curable pressure-sensitive adhesive, and after the silicon wafer mirror surface is attached to the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is cured by irradiating the pressure-sensitive adhesive layer with energy rays, and the pressure is 0.5 N / cm ² , 210. It is characterized in that the adhesive force between the silicon wafer mirror surface and the adhesive layer at 23 ° C. after thermocompression bonding at ° C. for 5 seconds is 9.0 N / 25 mm or less.
Hereinafter, the above-mentioned adhesive force may be referred to as "adhesive force after thermocompression bonding".

The adhesive force after thermocompression bonding can be controlled by the composition of the adhesive. A general guideline for controlling the adhesive force after thermocompression bonding will be described later.
The adhesive strength after thermocompression bonding is preferably in the range of 0.001 to 7 N / 25 mm, more preferably 0.1 to 1 N / 25 mm. When the adhesive strength after thermocompression bonding is within the above range, the chip group 20 can be stably held even after the pressure-sensitive adhesive layer is cured, and when the chip group is transferred to the pickup tape 30 or the adhesive tape. , The adhesive layer can be easily peeled off from the chip group without leaving a residue. When measuring the adhesive strength after thermocompression bonding, the adhesive is completely cured by irradiation with energy rays. That is, even if further energy ray irradiation is performed, the material is cured to the extent that the adhesive strength does not change. At this time, the peeling tape 50, which will be described later, is thermocompression bonded to the surface of the adhesive tape on the substrate side at the same time. The peeling tape 50 serves as a starting point for peeling and is also used for engaging the measuring device. In the measurement of the adhesive force after thermocompression bonding described later, the measured adhesive force may fluctuate as the peeling progresses. In the present invention, the maximum value until the peeling of the adhesive tape 10 is completed is called the adhesive force after thermocompression bonding.

Generally, the adhesive after curing has a reduced adhesive strength at room temperature, but when thermocompression bonding is performed, it adheres firmly to the adherend and tends to be difficult to peel off. However, the pressure-sensitive adhesive of the present invention does not excessively increase the adhesive strength even when thermocompression bonding is performed after curing, and maintains a relatively low adhesive strength. Since the adhesive strength after thermocompression bonding is within the above range, even if the peeling tape 50 is thermocompression bonded at a high temperature, the chips and the like are not embedded in the adhesive layer, and transfer defects of the chips can be significantly reduced.

Further, it is preferable that the storage elastic modulus of the pressure-sensitive adhesive at 23 ° C. before energy ray curing is 0.05 to 0.50 MPa. Further, the loss tangent (tan δ = loss modulus / storage modulus) at 23 ° C. before the energy ray curing is preferably 0.2 or more. Circuits and the like are formed on the surface of the semiconductor wafer and are usually uneven. The adhesive tape has the storage elastic modulus and tan δ of the adhesive within the above ranges, so that when the adhesive tape is attached to the uneven wafer surface, the unevenness of the wafer surface and the adhesive layer are sufficiently brought into contact with each other, and the adhesive It becomes possible to appropriately exert the adhesiveness of the layer. Therefore, the adhesive tape can be reliably fixed to the semiconductor wafer, and the wafer surface can be appropriately protected during backside grinding. From these viewpoints, the storage elastic modulus of the pressure-sensitive adhesive at 23 ° C. before energy ray curing is more preferably 0.10 to 0.35 MPa.

Further, it is preferable that the storage elastic modulus E _'200 at 200 ° C. after curing of the adhesive is not less than 1.5 MPa. Hereinafter, the storage elastic modulus at 200 ° C. after curing of the pressure-sensitive adhesive may be referred to as the storage elastic modulus after curing.

The storage elastic modulus after curing is more preferably in the range of 2.0 to 100 MPa, particularly preferably 2.5 to 70 MPa. After curing storage elastic modulus E _'200 is that in the above range, even after curing of the adhesive layer can hold a chip group 20 stably, and chip group to pick the tape 30 or adhesive tape At the time of transfer, the pressure-sensitive adhesive layer can be easily peeled off from the chip group without leaving a residue. When measuring the storage elastic modulus after curing, the adhesive is completely cured by irradiation with energy rays. That is, even if further energy beam irradiation is performed, the product is cured to such an extent that the elastic modulus does not change. Generally, the cured adhesive has a relatively high storage elastic modulus at room temperature, and tends to decrease as the temperature rises. However, the pressure-sensitive adhesive of the present invention maintains a high post-curing modulus of elasticity even at high temperatures. Therefore, according to the adhesive tape of the present invention, the adhesive layer after curing is unlikely to soften even if the conditions for thermocompression bonding the release tape 50 are high. As a result, even if the peeling tape is thermocompression bonded at a high temperature, transfer defects of the chip can be significantly reduced.

Further, the pressure-sensitive adhesive layer has an appropriate pressure-sensitive adhesive property at room temperature before the energy ray curing. The adhesive force of the pressure-sensitive adhesive layer before energy ray curing on the mirror surface of the silicon wafer at 23 ° C. is preferably in the range of 10 to 1500 mN / 25 mm, more preferably 10 to 700 mN / 25 mm.

The thickness (D3) of the pressure-sensitive 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 pressure-sensitive adhesive layer is thinned in this way, the proportion of low-rigidity portions of the pressure-sensitive adhesive tape can be reduced, so that it becomes easier to prevent chipping of the semiconductor chip that occurs during backside grinding.

The pressure-sensitive adhesive layer 12 is formed of, for example, an energy ray-curable pressure-sensitive adhesive mainly composed of an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, or the like. Sex adhesives are preferred.

Since the pressure-sensitive adhesive layer 12 is formed of an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive force and elastic modulus at 23 ° C. are set within the above ranges before curing by energy ray irradiation, and the pressure-sensitive adhesive force after curing. Can be easily set to 1000 mN / 50 mm or less. Here, the adhesive strength refers to the adhesive strength of the adhesive tape in the portion excluding the heat-sealing portion described later.

Further, the adhesive layer 12 has a breaking stress of preferably 10 MPa or more, particularly preferably 15 MPa or more in a state after energy ray curing. The elongation at break after energy ray curing is preferably 15% or more, and particularly preferably 20% or more. As described above, when the breaking stress value is 10 MPa or more and the breaking elongation value is 15% or more, the tensile physical properties of the energy ray-curable pressure-sensitive adhesive layer are good, and even if irradiation with ultraviolet rays or the like is insufficient. Therefore, even when the energy ray-curable pressure-sensitive adhesive layer is not sufficiently cured, it is possible to prevent the pressure-sensitive adhesive residue from adhering to the wafer.

Specific examples of the pressure-sensitive adhesive will be described in detail below, but these are non-limiting examples, and the pressure-sensitive adhesive layer in the present invention should not be construed as being limited to these.
Examples of the energy ray-curable adhesive include an energy ray-curable adhesive containing an energy ray-curable compound other than the adhesive resin in addition to a non-energy ray-curable adhesive resin (also referred to as “adhesive resin I”). An agent composition (hereinafter, also referred to as “X-type pressure-sensitive adhesive composition”) can be used. Further, as an energy ray-curable adhesive, an energy ray-curable adhesive resin (hereinafter, also referred to as "adhesive resin II") in which an unsaturated group is introduced into the side chain of a non-energy ray-curable adhesive resin is used. A pressure-sensitive adhesive composition (hereinafter, also referred to as “Y-type pressure-sensitive adhesive composition”) containing as a main component and not containing an energy ray-curable compound other than a pressure-sensitive adhesive resin may also be used.

Further, as the energy ray-curable pressure-sensitive adhesive, an energy ray-curable adhesive containing both X-type and Y-type, that is, an energy ray-curable adhesive resin II and an energy ray-curable compound other than the adhesive resin. A pressure-sensitive adhesive composition (hereinafter, also referred to as “XY type pressure-sensitive adhesive composition”) may be used.
Among these, it is preferable to use an XY type pressure-sensitive adhesive composition. By using the XY type, it is possible to have sufficient adhesive properties before curing, but to sufficiently reduce the adhesive force to the semiconductor wafer after curing.

In the following description, "adhesive resin" is used as a term referring to one or both of the above-mentioned adhesive resin I and adhesive resin II. Specific examples of the adhesive resin include acrylic resin, urethane resin, rubber resin, silicone resin and the like, but acrylic resin is preferable.
Hereinafter, the acrylic pressure-sensitive adhesive in which an acrylic resin is used as the pressure-sensitive adhesive resin will be described in more detail.

As the acrylic resin, the acrylic polymer (b) is used. The acrylic polymer (b) is obtained by polymerizing a monomer containing at least an alkyl (meth) acrylate, and contains a structural unit derived from the alkyl (meth) acrylate. Examples of the alkyl (meth) acrylate include those having an alkyl group having 1 to 20 carbon atoms, and the alkyl group may be linear or branched. Specific examples of alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) methacrylate, and 2-ethylhexyl (meth). ) Acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate and the like. The alkyl (meth) acrylate may be used alone or in combination of two or more.

Further, the acrylic polymer (b) preferably contains a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms from the viewpoint of improving the adhesive strength of the pressure-sensitive adhesive layer. The alkyl (meth) acrylate has preferably 4 to 12 carbon atoms, more preferably 4 to 6 carbon atoms. The alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms is preferably an alkyl acrylate.

In the acrylic polymer (b), the alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms is based on the total amount of monomers constituting the acrylic polymer (b) (hereinafter, also simply referred to as “total amount of monomers”). It is preferably 40 to 98% by mass, more preferably 45 to 95% by mass, and further preferably 50 to 90% by mass.

The acrylic polymer (b) is composed of an alkyl group in order to adjust the elastic modulus and adhesive properties of the pressure-sensitive adhesive layer, in addition to the structural unit derived from the alkyl (meth) aclate having 4 or more carbon atoms in the alkyl group. A copolymer containing a structural unit derived from an alkyl (meth) acrylate having 1 to 3 carbon atoms is preferable. The alkyl (meth) acrylate is preferably an alkyl (meth) acrylate having 1 or 2 carbon atoms, more preferably methyl (meth) acrylate, and most preferably methyl methacrylate. In the acrylic polymer (b), the alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms is preferably 1 to 30% by mass, more preferably 3 to 26% by mass, based on the total amount of the monomers. More preferably, it is 6 to 22% by mass.

The acrylic polymer (b) preferably has a structural unit derived from a functional group-containing monomer in addition to the structural unit derived from the alkyl (meth) acrylate described above. Examples of the functional group of the functional group-containing monomer include a hydroxyl group, a carboxy group, an amino group, an epoxy group and the like. The functional group-containing monomer reacts with a cross-linking agent described later to serve as a cross-linking starting point, or reacts with an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the acrylic polymer (b). Is possible.

Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxy group-containing monomer, an amino group-containing monomer, and an epoxy group-containing monomer. These monomers may be used alone or in combination of two or more. Among these, a hydroxyl group-containing monomer and a carboxy group-containing monomer are preferable, and a hydroxyl group-containing monomer is more preferable.

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

Examples of the carboxy 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 citraconic acid, and their anhydrides. , 2-Carboxyethyl methacrylate and the like.

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

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

The unsaturated group-containing compound is a compound having both a substituent capable of binding to a functional group of the acrylic polymer (b) and an energy ray-polymerizable unsaturated group. Examples of the energy ray-polymerizable unsaturated group include a (meth) acryloyl group, a vinyl group, an allyl group and the like, and a (meth) acryloyl group is preferable.
Examples of the substituent that can be bonded to the functional group of the unsaturated group-containing compound include an isocyanate group and a glycidyl group. Therefore, examples of the unsaturated group-containing compound include (meth) acryloyloxyethyl isocyanate, (meth) acryloyl isocyanate, and glycidyl (meth) acrylate.

Further, the unsaturated group-containing compound preferably reacts with a part of the functional groups of the acrylic polymer (b), and specifically, 50 to 98 mol of the functional groups of the acrylic polymer (b). % Is preferably reacted with an unsaturated group-containing compound, more preferably 55 to 93 mol%. As described above, in the energy ray-curable acrylic resin, a part of the functional groups remains without reacting with the unsaturated group-containing compound, so that the resin is easily crosslinked by the cross-linking agent.
The weight average molecular weight (Mw) of the acrylic resin is preferably 300,000 to 1.6 million, more preferably 400,000 to 1.4 million, and even more preferably 500,000 to 1.2 million. The glass transition temperature (Tg) of the acrylic resin is preferably −70 to 10 ° C.

(Energy ray curable compound)
As the energy ray-curable compound contained in the X-type or XY-type pressure-sensitive adhesive composition, a monomer or oligomer having an unsaturated group in the molecule and capable of polymerizing and curing by energy ray irradiation is preferable.
Examples of such energy ray-curable compounds include trimethylpropantri (meth) acrylate, pentaerythritol (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 1,4-. Polyvalent (meth) acrylate monomers such as butylene glycol di (meth) acrylate and 1,6-hexanediol (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, epoxy ( Examples thereof include oligomers such as meta) acrylate. The molecular weight of the energy ray-curable compound (weight average molecular weight in the case of an oligomer) is preferably 100 to 12000, more preferably 200 to 10000, still more preferably 400 to 8000, and particularly preferably 600 to 6000.

Among these, urethane (meth) acrylate oligomers are preferable from the viewpoint of having a relatively high molecular weight and not easily lowering the elastic modulus of the pressure-sensitive adhesive layer.

A preferable urethane (meth) acrylate oligomer is a compound containing an isocyanate unit and a polyol unit and having a (meth) acryloyl group at the end. As the urethane (meth) acrylate, a urethane oligomer is produced by reacting a polyol having a hydroxyl group at the terminal such as an alkylene polyol, a polyether compound, or a polyester compound with polyisocyanate, and (meth) acryloyl is used as a functional group at the terminal. Examples thereof include a compound obtained by reacting a compound having a group. Such urethane (meth) acrylate has energy ray curability due to the action of the (meth) acryloyl group.

Examples of the above-mentioned polyisocyanate include isophorone diisocyanate (IPDI), 1,3-bis- (isocyanatomethyl) -cyclohexane (H6XDI), and 4,4'-dicyclohexylmethane diisocyanate (H12MDI). Used. These polyisocyanates are preferably used in an energy ray-curable urethane (meth) acrylate in an amount of 40 to 49 mol%. Further, among these diisocyanates, isophorone diisocyanate (IPDI), which can improve the compatibility of the energy ray-curable urethane (meth) acrylate with respect to the energy ray-curable acrylic polymer, can be used. Especially preferable.

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

The energy ray-curable urethane (meth) acrylate is preferably 1 to 200 parts by mass, more preferably 5 to 100 parts by mass, and further preferably 10 to 50 parts by mass with respect to 100 parts by mass of the energy ray-curable acrylic polymer. Used in proportions of parts. The molecular weight of the urethane (meth) acrylate is preferably 300 to 30,000 as a number average molecular weight from the viewpoint of compatibility with the energy ray-curable acrylic polymer, processability of the energy ray-curable pressure-sensitive adhesive layer, and the like. It is a range of degrees. More preferably, it is 20,000 or less, for example 1,000 to 15,000 oligomers.

The content of the energy ray-curable compound in the X-type pressure-sensitive adhesive composition is preferably 40 to 200 parts by mass, more preferably 50 to 150 parts by mass, and further preferably 60 to 60 parts by mass with respect to 100 parts by mass of the pressure-sensitive adhesive resin. It is 90 parts by mass.
On the other hand, the content of the energy ray-curable compound in the XY type pressure-sensitive adhesive composition is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, still more preferably, with respect to 100 parts by mass of the pressure-sensitive adhesive resin. Is 3 to 15 parts by mass. In the XY type pressure-sensitive adhesive composition, since the adhesive resin is energy ray-curable, even if the content of the energy ray-curable compound is small, the adhesive strength can be sufficiently lowered after the energy ray irradiation. Is.

(Crosslinking agent)
The pressure-sensitive adhesive composition preferably further contains a cross-linking agent. The cross-linking agent, for example, reacts with a functional group derived from a functional group monomer of the adhesive resin to cross-link the adhesive resins with each other. Examples of the cross-linking agent include isocyanate-based cross-linking agents such as tolylene diisocyanate, hexamethylene diisocyanate, and their adducts; epoxy-based cross-linking such as 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane. Agents; isocyanate-based cross-linking agents such as hexa [1- (2-methyl) -aziridinyl] triphosphatriazine; chelate-based cross-linking agents such as aluminum chelate; and the like. These cross-linking agents may be used alone or in combination of two or more.

Among these, an isocyanate-based cross-linking agent is preferable from the viewpoint of increasing the cohesive force to improve the adhesive force and the availability.
From the viewpoint of accelerating the cross-linking reaction, the amount of the cross-linking agent is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and further preferably 0 with respect to 100 parts by mass of the adhesive resin. .05-4 parts by mass.

(Photopolymerization initiator)
Further, the pressure-sensitive adhesive composition preferably further contains a photopolymerization initiator. By containing the photopolymerization initiator, the curing reaction of the pressure-sensitive adhesive composition can be sufficiently advanced even with relatively low-energy energy rays such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphinoxide compounds, titanosen compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. Specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl. Examples thereof include sulfide, tetramethylthiuram monosulfide, azobisisobutyrolnitrile, dibenzyl, diacetyl, 8-chloranthraquinone, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide and the like.

These photopolymerization initiators may be used alone or in combination of two or more.
The blending amount of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and further preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the adhesive resin. Is.

(Other additives)
The pressure-sensitive adhesive composition may contain other additives as long as the effects of the present invention are not impaired. Examples of other additives include antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes and the like. When these additives are blended, the blending amount of the additives is preferably 0.01 to 6 parts by mass with respect to 100 parts by mass of the adhesive resin.

Further, the pressure-sensitive adhesive composition may be further diluted with an organic solvent in the form of a solution of the pressure-sensitive adhesive composition from the viewpoint of improving the coatability on the base material or the release sheet.
Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol and the like.
As these organic solvents, the organic solvent used at the time of synthesizing the adhesive resin may be used as it is, or other than the organic solvent used at the time of synthesis so that the solution of the pressure-sensitive adhesive composition can be uniformly applied. One or more organic solvents of the above may be added.

(Control of adhesive force after thermocompression bonding)
Since the adhesive strength of the energy ray-curable adhesive constituting the pressure-sensitive adhesive layer 12 after thermocompression bonding is within the above range, even if the peeling tape 50 is thermocompression-bonded, the chips and the like are not embedded in the pressure-bonding layer, and the chips Transfer defects can be significantly reduced.

The adhesive force after thermocompression bonding can be controlled by the composition of the adhesive. For example, by increasing the degree of cross-linking of the pressure-sensitive adhesive after energy ray curing, the pressure-bonding force after thermocompression bonding can be reduced. Therefore, by increasing the amount of the cross-linking agent to be blended in the pressure-sensitive adhesive or by using a cross-linking agent having a large number of functional groups, the degree of cross-linking of the pressure-sensitive adhesive can be increased and the adhesive strength after thermocompression bonding can be lowered. Further, by using an acrylic resin having a relatively high Tg as the adhesive resin, it is possible to reduce the adhesive force after thermocompression bonding.

However, with these methods, the adhesive strength before the energy ray curing becomes low, and sufficient pressure-sensitive adhesiveness may not be obtained before the energy ray curing. Therefore, for example, it is also effective to increase the density of energy ray-polymerizable unsaturated groups contained in the pressure-sensitive adhesive. Specifically, the amount of the energy ray-curable unsaturated group introduced into the energy ray-curable adhesive resin II is increased, the amount of the energy ray-curable compound is increased, and the energy ray-curable compound is unsaturated. By using a compound having a large number of groups or by increasing the blending amount of the photopolymerization initiator, a highly crosslinked structure is formed by energy ray curing, and the adhesive strength after thermal pressure bonding can be controlled to be low.

Generally, the cured pressure-sensitive adhesive has a relatively low adhesive strength at room temperature, and the adhesive strength tends to increase as the temperature rises. However, by introducing a highly crosslinked structure into the pressure-sensitive adhesive, the pressure-sensitive adhesive layer is suppressed from softening and flowing at high temperatures, and maintains low adhesive strength. As a result, even if the peeling tape 50 is thermocompression bonded, the chips and the like are not embedded in the pressure-sensitive adhesive layer, and transfer defects can be suppressed.

Further, if the adhesive layer is excessively cured after curing, the adhesive tape is less likely to be deformed, which may make it difficult to peel off the adhesive tape after curing. In this case, by using a base material having a relatively high flexibility as the base material 11, peeling may be facilitated. If the base material is flexible, the adhesive tape 10 can be folded back at the time of peeling, and the peeling angle becomes large. For this reason, the contact area between the chip and the pressure-sensitive adhesive layer at the portion where the peeling is progressing becomes small, so that the peeling can be performed with a relatively small force. On the other hand, if the base material is too hard, the peeling angle becomes small, the contact area between the chip and the pressure-sensitive adhesive layer at the portion where the peeling is progressing is large, and the adhesive force (peeling force) becomes high. For the same reason, reducing the thickness of the base material is also effective in facilitating peeling. However, if the base material is excessively flexible or too thin, the operability of the adhesive tape deteriorates, vibration during backside grinding cannot be suppressed, and the semiconductor chip may be chipped or damaged. ..

Therefore, it is preferable to control the peelability of the adhesive tape 10 by appropriately setting the physical properties of the pressure-sensitive adhesive layer 12 and the Young's modulus and thickness of the base material 11.

[Peeling sheet]
A release sheet may be attached to the surface of the adhesive tape. Specifically, the release sheet is attached to the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape. The release sheet is attached to the surface of the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer during transportation and storage. The release sheet is detachably attached to the adhesive tape, and is peeled off from the adhesive tape before the adhesive tape is used (that is, before grinding the back surface of the wafer).
As the release sheet, a release sheet in which at least one surface has been peeled is used, and specific examples thereof include a release sheet coated with a release agent on the surface of the base material for the release sheet.

A resin film is preferable as the base material for the release sheet, and examples of the resin constituting the resin film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin, polypropylene resin, and polyethylene resin. Examples thereof include the polyolefin resin of. Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.
The thickness of the release 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 method for producing the adhesive tape 10 of the present invention is not particularly limited, and the adhesive tape 10 can be produced by a known method.
For example, by applying a buffer layer forming composition on a release sheet, curing the buffer layer, and the base material, and removing the release sheet, a laminate of the buffer layer and the base material can be obtained. can get. Then, the pressure-sensitive adhesive layer provided on the release sheet can be attached to the base material side of the laminate to produce an adhesive tape in which the release sheet is attached to the surface of the pressure-sensitive adhesive layer. When the buffer layer is provided on both sides of the base material, the pressure-sensitive adhesive layer is formed on the buffer layer. The release sheet attached to the surface of the pressure-sensitive adhesive layer may be appropriately peeled off and removed before using the pressure-sensitive adhesive tape.

As a method of forming a buffer layer on the release sheet, the buffer layer forming composition is directly applied onto the release sheet by a known coating method to form a coating film, and the coating film is irradiated with energy rays. By doing so, a buffer layer can be formed. Further, the buffer layer may be formed by directly coating the composition for forming a buffer layer on one side of the base material and drying by heating or irradiating the coating film with energy rays.

Examples of the coating method of the buffer layer forming composition include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method. Further, in order to improve the coatability, an organic solvent may be blended with the composition for forming a buffer layer and coated on a release sheet in the form of a solution.

When the composition for forming a buffer layer contains an energy ray-polymerizable compound, it is preferable that the coating film of the composition for forming a buffer layer is cured by irradiating the coating film with energy rays to form a buffer layer. The buffer layer may be cured by a single curing treatment or may be performed in a plurality of times. For example, the coating film on the release sheet may be completely cured to form a buffer layer and then bonded to the base material, or the coating film may not be completely cured to form a semi-cured buffer layer forming film. Then, after the buffer layer forming film is attached to the base material, the buffer layer may be formed by irradiating with energy rays again and completely curing the film. Ultraviolet rays are preferable as the energy rays to be irradiated in the curing treatment. When curing, the coating film of the buffer layer forming composition may be exposed, but the coating film is covered with a release sheet or a base material, and energy rays are irradiated in a state where the coating film is not exposed. It is preferable to cure.

As a method of forming the pressure-sensitive adhesive layer on the release sheet, a pressure-sensitive adhesive (adhesive composition) is directly applied onto the release sheet by a known coating method, and the coating film is heated and dried to obtain a pressure-sensitive adhesive. Layers can be formed.

Further, the pressure-sensitive adhesive (adhesive composition) may be directly applied on one side of the base material or on the buffer layer to form the pressure-sensitive adhesive layer. Examples of the method for applying the adhesive include the spin coating method, the spray coating method, the bar coating method, the knife coating method, the roll coating method, the blade coating method, the die coating method, and the gravure coating method shown in the method for producing the buffer layer. Be done.

[Manufacturing method of semiconductor devices]
The adhesive tape 10 of the present invention is particularly preferably used as a back grind tape to be attached to the wafer circuit surface when backside grinding is performed while protecting the semiconductor wafer circuit surface in the pre-dicing method. A non-limiting example of use as a backgrinding tape will be described in more detail by taking the production of a semiconductor device as an example.

Specifically, the method for manufacturing a semiconductor device includes at least the following steps 1 to 4.
Step 1: Forming a groove from the surface side of the semiconductor wafer Step 2: Attaching the above-mentioned adhesive tape 10 (back grind tape) to the surface of the semiconductor wafer Step 3: The adhesive tape 10 is attached to the surface and A step of grinding a semiconductor wafer having the grooves formed from the back surface side, removing the bottom of the grooves, and individualizing the semiconductor wafer into a plurality of chips (chip group 20) (see FIG. 1).
Step 4: The step of transferring the chip group 20 to the pickup tape 30 or the adhesive tape (see FIGS. 2 to 5) and peeling the individual chips from the pickup tape or the adhesive tape.

Hereinafter, each step of the method for manufacturing the semiconductor device will be described in detail.
(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 groove can be formed by dicing using a conventionally known wafer dicing apparatus or the like. Further, the semiconductor wafer is divided into a plurality of semiconductor chips along the groove by removing the bottom portion of the groove in step 3 described later.

The semiconductor wafer used in this manufacturing method may be a silicon wafer, a wafer such as gallium arsenide or arsenide, a sapphire wafer, or a glass wafer. The thickness of the semiconductor wafer before grinding is not particularly limited, but is usually about 500 to 1000 μm. Further, a semiconductor wafer usually has a circuit formed on its surface. The circuit can be formed on the wafer surface by various methods including a conventionally used method such as an etching method and a lift-off method.

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

(Step 3)
After the steps 1 and 2, the back surface of the semiconductor wafer on the suction table is ground to separate the semiconductor wafer into a plurality of semiconductor chips.
Here, when the groove is formed on the semiconductor wafer, the back surface grinding is performed so as to thin the semiconductor wafer at least to a position reaching the bottom of the groove. By this backside grinding, the groove becomes a notch penetrating the wafer, and the semiconductor wafer is divided by the notch and individualized into individual semiconductor chips.

The shape of the individualized semiconductor chip may be a square shape or an elongated shape such as a rectangle. The thickness of the fragmented semiconductor chip is not particularly limited, but is preferably about 5 to 100 μm, and more preferably 10 to 45 μm. The size of the fragmented semiconductor chip is not particularly limited, but the chip size is preferably ^{less than 200 mm 2} , more preferably less than 150 mm ² , and even more preferably less than ^{120 mm 2.}

Through the above steps, the chip group 20 is obtained on the adhesive tape (back grind tape) 10 as shown in FIG. Further, after the back surface grinding is completed, dry polishing may be performed prior to picking up the chips.

(Step 4)
Next, the individualized chip group 20 is transferred from the back grind tape to the pickup tape 30 or the adhesive tape, and the individual chips 21 are peeled off from the pickup tape or the adhesive tape. Hereinafter, this step will be described based on an example using a pickup tape.

First, the pressure-sensitive adhesive layer 12 of the pressure-sensitive adhesive tape 10 is irradiated with energy rays to cure the pressure-sensitive adhesive layer. Next, the pickup tape 30 is attached to the back surface side of the chip group 20 (FIG. 2), and the position and direction are adjusted so that the pickup can be picked up. At this time, the ring frame 40 arranged on the outer peripheral side of the chip group 20 is also attached to the pick-up tape 30, and the outer peripheral edge portion of the pickup tape 30 is fixed to the ring frame 40. The chip group 20 and the ring frame 40 may be attached to the pickup tape 30 at the same time, or may be attached at different timings. Next, only the back grind tape 10 is peeled off, and the chip group 20 is transferred onto the pickup tape.

When the back grind tape 10 is peeled off, the peeling tape 50 that serves as a trigger for peeling is fixed to the back surface (base material surface) of the back grind tape 10 (FIG. 3). Since the back grind tape has substantially the same shape as the semiconductor wafer and does not have a starting point for peeling, the strip-shaped peeling tape 50 is fixed as a starting point for peeling. The peeling tape 50 is firmly fixed to the back surface of the back grind tape 10 by thermocompression bonding.
As shown in FIGS. 4 and 5, it is preferable that the back grind tape 10 is peeled off so that the back grind tape 10 is folded back from the peeling tape 50 as a starting point.

After that, if necessary, the pickup tape 30 is expanded to separate the chip intervals, and the individual semiconductor chips 21 on the pickup tape 30 are picked up and fixed on a substrate or the like to manufacture a semiconductor device.

The pickup tape 30 is not particularly limited, but is composed of, for example, a base material and an adhesive tape called a dicing tape having an adhesive layer provided on one surface of the base material. The adhesive strength of the pickup tape 30 may be larger than the adhesive strength of the back grind tape 30 at the time of peeling. Further, when the chip 21 is peeled from the pickup tape 30, it is preferable that the chip 21 has a property of reducing the adhesive force. Therefore, as the pickup tape, an energy ray-curable adhesive tape is preferably used.

Also, an adhesive tape can be used instead of the pickup tape. The adhesive tape is composed of a laminate of a film-like adhesive and a release sheet, a laminate of a dicing tape and a film-like adhesive, and an adhesive layer and a release sheet having the functions of both a dicing tape and a die bonding tape. Examples include dicing and die bonding tapes. Further, before attaching the pickup tape, a film-like adhesive may be attached to the back surface side of the individualized semiconductor wafer. When a film-like adhesive is used, the film-like adhesive may have the same shape as the wafer.

When using an adhesive tape or when applying a film-like adhesive to the back side of a semiconductor wafer that has been separated before attaching the pickup tape, the plurality of semiconductor chips on the adhesive tape or pickup tape are semiconductors. It is picked up with an adhesive layer divided into the same shape as the chip. Then, the semiconductor chip is fixed on a substrate or the like via an adhesive layer, and a semiconductor device is manufactured. The division of the adhesive layer is performed by laser or expanding.

The peeling tape 50 is not particularly limited as long as it is a material that can be firmly heat-sealed on the back surface of the base material of the adhesive tape 10. Therefore, the peeling tape 50 is appropriately selected in consideration of the material of the base material 11 of the adhesive tape 10. The base material 11 in the present invention is preferably composed of a polyester-based film such as polyethylene terephthalate. Therefore, as the peeling tape 50, a polyolefin-based tape having good heat-sealing property with a polyester-based film is preferably used. Examples of such polyolefin tapes include, but are not limited to, polyethylene tapes and polypropylene tapes.

The peeling tape 50 is cut into strips and is not limited in any way, but usually has a width of about 50 mm and a length of 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 surface (base material 11) of the adhesive tape 10, both can be firmly heat-sealed by performing thermocompression bonding. The thermocompression bonding conditions vary depending on the material of the base material 11 and the material of the peeling tape 50. Generally, the pressure is ^{about 0.2 to 1 N / cm 2} and the temperature is about 120 to 250 ° C. for 0.5 to 10 seconds. Thermocompression bonding may be performed to some extent. Further, at the time of thermocompression bonding, a heat seal portion is provided with an area sufficient for the peeling tape 50 to be sufficiently fixed to the base material 11. For example, it is preferable that a region of about 0.1 to 3 mm from the outer edge portion of the base material 11 toward the base material 11 toward the center is a heat-sealed portion.

As described above, when the peeling tape 50 is thermocompression bonded to the back surface (base material 11) of the adhesive tape 10, heat and pressure propagate to the adhesive layer 12 of the adhesive tape 10, and the chip 21 and the adhesive layer 12 Is thermocompression bonded. When the adhesive strength increases after thermocompression bonding, the chip firmly adheres to the adhesive layer 12, and when the adhesive tape 10 is peeled off, the chip may be peeled off along with the adhesive tape 10 to cause transfer failure of the chip. .. However, in the present invention, since the adhesive force of the adhesive tape 10 after thermocompression bonding is controlled within a predetermined range, transfer defects of the chip can be reduced.

As described above, the "adhesive force after thermocompression bonding" in the present invention refers to the adhesive force at 23 ° C. after thermocompression bonding at a ^{pressure of 0.5 N / cm 2 and 210 ° C. for 5 seconds.} It has been experimentally confirmed that there is no significant difference in adhesive strength even if the pressure during thermocompression bonding is increased, the temperature is increased, or the time is lengthened. That is, the thermocompression bonding conditions (pressure 0.5 N / cm ² , 210 ° C. for 5 seconds) for measuring the adhesive force after thermocompression bonding specified in the present invention are sufficiently harsh conditions, and the conditions are more severe than this. There is no big difference in adhesive strength even if it is harsh. Therefore, by controlling the adhesive force after thermocompression bonding within the range specified in the present application, the adhesive force between the chip surface and the adhesive tape 10 can be maintained at a low level even under various thermocompression bonding conditions, and the effect of the present invention is exhibited. ..

The example in which the adhesive tape of the present invention is mainly used for the method of individualizing the semiconductor wafer by the pre-dicing method has been described, but the adhesive tape of the present invention can also be used for ordinary backside grinding. Also, it can be used to temporarily fix the workpiece during processing of glass, ceramics, etc. It can also be used as various removable adhesive tapes.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

The measurement method and evaluation method in the present invention are as follows.

[Storage modulus after curing]
The pressure-sensitive adhesive composition prepared in Examples and Comparative Examples is coated and dried on a release sheet (manufactured by Lintec Corporation, SP-PET3801, thickness: 38 μm) in which one side of a polyethylene terephthalate film is peeled off with a silicone-based release agent. Then, a pressure-sensitive adhesive layer having a thickness of 20 μm was prepared. A plurality of layers of the obtained pressure-sensitive adhesive layer were laminated so as to have a thickness of 3 mm. A cylinder (height 3 mm) having a diameter of 8 mm was punched out from the obtained laminated body of the pressure-sensitive adhesive layer, and this was used as a sample. The sample was irradiated with ultraviolet light to completely cure the pressure-sensitive adhesive layer. The above-mentioned ultraviolet irradiation conditions are a wavelength of 365 nm, an illuminance of 150 mW / cm ² , and a light intensity of 300 mJ / cm ² .

For the cured samples, the storage elastic modulus E'at a frequency of 11 Hz and a temperature of 200 ° C. was measured for 10 samples by a dynamic viscoelastic device (manufactured by Orientec, trade name "Rheovibron DDV-II-EP1"). ..
[Adhesive strength after thermocompression bonding]
Adhesive tape with a release sheet obtained in Examples and Comparative Examples is applied to the polished surface of a bare wafer (diameter 12 inches, thickness 740 μm, # 2000 polishing), and a tape laminator (manufactured by Lintec Corporation, product name) while peeling off the release sheet. It was set on "RAD-3510F / 12") and attached. Then, the outer peripheral portion of the adhesive tape was cut off to have the same shape as the bare wafer.

Then, with a mounter equipped with an ultraviolet irradiation / tape peeling device (manufactured by Lintec Corporation, trade name "RAD-2700"), ultraviolet rays were irradiated from the substrate surface side of the adhesive tape to completely cure the adhesive layer. The above-mentioned ultraviolet irradiation conditions are a wavelength of 365 nm, an illuminance of 150 mW / cm ² , and a light intensity of 300 mJ / cm ² . Next, as a pickup tape, a dicing tape (Adwill D-175 manufactured by Lintec Corporation) was attached to the other surface of the bare wafer. Next, as a peeling tape, a polypropylene film having a width of 50 mm and a length of 60 mm (Adwill S-75C manufactured by Lintec Corporation) was prepared. Heat sealing was performed at a pressure of 0.5 N / cm ² and 210 ° C. for 5 seconds with a heat sealing device, and a peeling tape was thermocompression bonded to the outer edge of the adhesive tape. The heat-sealed portion is a region of 2 mm from the outer edge portion of the adhesive tape toward the center.

The peeling tape was peeled from the bare wafer by a tensile tester (manufactured by Shimadzu Corporation, Autograph AG-IS) at a peeling speed of 300 mm / min and a peeling angle of 180 °. The maximum peeling force from the start of peeling to the complete peeling of the heat-sealed portion (about 1 cm) was measured. The maximum peeling force was measured for 10 adhesive tapes, and the average value was taken as the adhesive force after thermocompression bonding.

[Peeling evaluation]
Grooves with a depth of 70 μm and a width of 30 μm are formed on the polished surface of the bare wafer in the same manner as in the measurement of the adhesive force after thermocompression bonding at 1 mm intervals in the vertical and horizontal directions of the wafer, and the adhesive tape (back) is formed on the same surface. Grind tape) was attached. Then, the back surface side of the wafer was ground and separated into pieces having a thickness of 30 μm and a chip size of 1 mm × 1 mm by a pre-dicing method.

After the back surface grinding is completed, the adhesive layer is completely cured by irradiating the adhesive tape with ultraviolet rays from the base material surface side with a mounter with an ultraviolet irradiation / tape peeling device (manufactured by Lintec Corporation, trade name "RAD-2700"). did. The above-mentioned ultraviolet irradiation conditions are a wavelength of 365 nm, an illuminance of 150 mW / cm ² , and a light intensity of 300 mJ / cm ² . Then, as a pickup tape, a dicing tape (Adwill D-175 manufactured by Lintec Corporation) was attached to the chip group, and the outer peripheral portion of the dicing tape was fixed with a ring frame. Next, as a peeling tape, a polypropylene film having a width of 50 mm and a length of 60 mm (Adwill S-75C manufactured by Lintec Corporation) was prepared. Heat sealing was performed at a pressure of 0.5 N / cm ² and 210 ° C. for 5 seconds with a heat sealing device, and a peeling tape was thermocompression bonded to the outer edge of the adhesive tape. The heat-sealed portion is a region of 2 mm from the outer edge portion of the adhesive tape toward the center.

The adhesive tape was peeled off from the chip group while holding the peeling tape and folding back the adhesive tape. The number of chips left on the adhesive layer of the adhesive tape was confirmed.
By the above operation, the number of chips remaining on the adhesive tape was totaled and evaluated according to the following criteria.
Excellent: Less than 10 Good: 10 or more and less than 30 Defective: 30 or more

The mass parts of the following Examples and Comparative Examples are all solid content values.
The following multi-layer base material was prepared.
(1) Multi-layer base material 1
A polyethylene terephthalate film (Young's modulus: 2500 MPa) having a thickness of 50 μm was used as a base material. A multi-layer base material 1 provided with the following buffer layer on this base material was prepared.

(Composition for forming a buffer layer)
(Synthesis of urethane acrylate oligomer)
A urethane acrylate-based oligomer (UA-1) having a weight average molecular weight (Mw) of about 5000 by reacting 2-hydroxyethyl acrylate with a terminal isocyanate urethane prepolymer obtained by reacting a polycarbonate diol with isophorone diisocyanate. Got

50 parts by mass of urethane acrylate-based oligomer (UA-1) synthesized above, 30 parts by mass of isobornyl acrylate (IBXA), 40 parts by mass of tetrahydrofurfuryl acrylate (THFA), and dipentaerythritol hexaacrylate (DPHA) 15 A part by mass is blended, and further, 1.0 part by mass of 2-hydroxy-2-methyl-1-phenyl-propane-1-one (manufactured by BASF Japan, product name "DaroCure 1173") as a photopolymerization initiator is blended. Then, a composition for forming a buffer layer was prepared.

(Preparation of multi-layer base material 1)
The composition for forming a buffer layer was applied to the peeled surface of the peeling sheet (manufactured by Lintec Corporation, trade name "SP-PET38131") to form a coating film. Next, the coating film was irradiated with ultraviolet rays, and the coating film was semi-cured to form a buffer layer forming film having a thickness of 53 μm.
For the above ultraviolet irradiation, a belt conveyor type ultraviolet irradiation device (manufactured by Eye Graphics, device name "US2-0801") and a high-pressure mercury lamp (manufactured by Eye Graphics, device name "H08-L41") are used. The irradiation was performed under irradiation conditions of a lamp height of 230 mm, an output of 80 mW / cm, a light wavelength of 365 nm, an illuminance of 90 mW / cm ² , and an irradiation amount of 50 mJ / cm ^2.

Then, the surface of the formed buffer layer forming film and the PET base material are adhered to each other, and ultraviolet rays are irradiated again from the release sheet side on the buffer layer forming film to completely cure the buffer layer forming film to obtain a thickness. A 53 μm buffer layer was formed, and a multi-layer substrate 1 composed of a PET substrate and a buffer layer was prepared. The above-mentioned ultraviolet irradiation uses the above-mentioned ultraviolet irradiation device and a high-pressure mercury lamp, and irradiates with a lamp height of 220 mm, a conversion output of 120 mW / cm ^{, an illuminance of 160 mW / cm 2 with} a light wavelength of 365 nm, and an irradiation amount of 350 mJ / cm ² . It was performed under the conditions.

(2) Multi-layer base material 2-4
A polyethylene terephthalate (PET) film was used as a base material. A multi-layer base material provided with the following buffer layer on this base material was prepared. As the buffer layer, low density polyethylene (LDPE) having a thickness of 27.5 μm was used.
Multi-layer substrate 2: LDPE (27.5 μm) / PET (25.0 μm) / LDPE (27.5 μm)
Multi-layer substrate 3: LDPE (27.5 μm) / PET (50 μm) / LDPE (27.5 μm)
Multi-layer substrate 4: LDPE (27.5 μm) / PET (75.0 μm) / LDPE (27.5 μm)

(3) Adhesive Layer The following adhesive compositions A to E were prepared.
(Preparation of Adhesive Composition A)
An acrylic polymer obtained by copolymerizing 65 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 15 parts by mass of 2-hydroxyethyl acrylate (2HEA) in ethyl acetate. 2-methacryloyloxyethyl isocyanate (MOI) is reacted so as to be added to 80 mol% of all hydroxyl groups of the acrylic polymer to obtain an energy ray-curable acrylic resin (Mw: 500,000). It was.

1 part by mass (solid ratio) of a tolylene diisocyanate-based cross-linking agent (manufactured by Toso Co., Ltd., product name "Coronate L") and a photopolymerization initiator (Ciba) with respect to 100 parts by mass of the above-mentioned energy ray-curable acrylic polymer. Product name "Irgacure 184") manufactured by Specialty Chemicals Co., Ltd.) 3.3 parts by mass (solid ratio) was mixed to obtain an energy ray-curable pressure-sensitive adhesive composition A.

(Preparation of Adhesive Composition B)
89 parts by mass of n-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 above acrylic polymer, 1 part by mass (solid content) of a tolylene isocyanate-based cross-linking agent (manufactured by Toso Co., Ltd., product name "Coronate L") and an epoxy-based cross-linking agent (1,3- Bis (N, N-diglycidylaminomethyl) cyclohexane) 2 parts by mass (solid content) and UV curable resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name "Shikou UV-3210EA") 45 parts by mass (solid content) ) And 1 part by mass (solid content) of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals Co., Ltd., product name “Irgacure 184”) to obtain an energy ray-curable pressure-sensitive adhesive composition B. The storage elastic modulus after curing was measured using the obtained adhesive composition.

(Preparation of Adhesive Composition C)
The acrylic polymer is added to an acrylic polymer obtained by copolymerizing 50 parts by mass of n-butyl acrylate (BA), 25 parts by mass of methyl methacrylate (MMA), and 25 parts by mass of 2-hydroxyethyl acrylate (2HEA). 2-methacryloyloxyethyl isocyanate (MOI) was reacted so as to be added to 90 mol% of the total hydroxyl groups in the above, to obtain an energy ray-curable acrylic polymer (Mw: 500,000).

With respect to 100 parts by mass of the above-mentioned 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, tolylene diisocyanate-based cross-linking. 1 part by mass (solid content) of the agent (manufactured by Toso Co., Ltd., trade name "Coronate L") and 1.16 parts by mass (solid ratio) of the photopolymerization initiator (manufactured by Ciba Specialty Chemicals, Irgacure 184) are mixed. An energy ray-curable pressure-sensitive adhesive composition C was obtained. The storage elastic modulus after curing was measured using the obtained adhesive composition.

(Preparation of Adhesive Composition D)
The acrylic polymer is added to an acrylic polymer obtained by copolymerizing 60 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 20 parts by mass of 2-hydroxyethyl acrylate (2HEA). 2-methacryloyloxyethyl isocyanate (MOI) was reacted so as to be added to 80 mol% of the total hydroxyl groups in the above, to obtain an energy ray-curable acrylic polymer (Mw: 450,000).

To 100 parts by mass of the above-mentioned energy ray-curable acrylic polymer, 0.7 parts by mass (solid content) of a tolylene diisocyanate-based cross-linking agent (manufactured by Toso Co., Ltd., trade name "Coronate L") and a photopolymerization initiator (solid content) 1.16 parts by mass (solid ratio) of Irgacure 184) manufactured by Ciba Specialty Chemicals Co., Ltd. was mixed to obtain an energy ray-curable pressure-sensitive adhesive composition D. The storage elastic modulus after curing was measured using the obtained adhesive composition.

(Preparation of Adhesive Composition E)
89 parts by mass of n-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). ..

1 part by mass (solid content) of tolylene diisocyanate-based cross-linking agent (manufactured by Toso Co., Ltd., product name "Coronate L"), UV curable resin (Nippon Synthetic Chemical Industry Co., Ltd.) with respect to 100 parts by mass of the above acrylic polymer. Made by Co., Ltd., product name "Shikou UV-3210EA") 22 parts by mass (solid content) and photopolymerization initiator (manufactured by Ciba Specialty Chemicals Co., Ltd., product name "Irgacure 184") 1.16 parts by mass (solid content) Was mixed to obtain an energy ray-curable pressure-sensitive adhesive composition E. The storage elastic modulus after curing was measured using the obtained adhesive composition.

[Example 1]
The peeling surface of the peeling sheet (manufactured by Lintec Corporation, trade name "SP-PET38131") is coated with the coating liquid of the energy ray-curable adhesive composition A obtained above, and dried by heating at 100 ° C. for 1 minute. A pressure-sensitive adhesive layer having a thickness of 20 μm was formed on the release sheet.

An adhesive layer was attached to the opposite surface of the multi-layer base material 1 on which the buffer layer was formed to prepare an adhesive tape. The adhesive strength of the obtained adhesive tape after thermocompression bonding was measured, and peeling evaluation was performed.

[Example 2]
An adhesive tape was produced in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was 50 μm using the multilayer base material 2 and the pressure-sensitive adhesive composition B. The pressure-sensitive adhesive layer was provided on the LDPE layer, which is a buffer layer. The adhesive strength of the obtained adhesive tape after thermocompression bonding was measured, and peeling evaluation was performed.

[Example 3]
An adhesive tape was produced in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was set to 20 μm using the multilayer base material 3 and the pressure-sensitive adhesive composition C. The pressure-sensitive adhesive layer was provided on the LDPE layer, which is a buffer layer. The adhesive strength of the obtained adhesive tape after thermocompression bonding was measured, and peeling evaluation was performed.

[Example 4]
An adhesive tape was produced in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was set to 40 μm by using the multilayer base material 4 and the pressure-sensitive adhesive composition D. The pressure-sensitive adhesive layer was provided on the LDPE layer, which is a buffer layer. The adhesive strength of the obtained adhesive tape after thermocompression bonding was measured, and peeling evaluation was performed.

[Comparative Example 1]
An adhesive tape was produced in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was 20 μm using the multilayer base material 3 and the pressure-sensitive adhesive composition E. The pressure-sensitive adhesive layer was provided on the LDPE layer, which is a buffer layer. The adhesive strength of the obtained adhesive tape after thermocompression bonding was measured, and peeling evaluation was performed.

From the above results, if the adhesive strength after thermocompression bonding is 9.0 N / 25 mm or less, there is no chip transfer defect in the heat-sealed portion even if the peeling tape is thermocompression bonded, and the chip is attached to the pickup tape or the adhesive tape. It can be seen that the transfer can be performed well. In addition to the adhesive tapes described in detail in Examples and Comparative Examples, good results can be obtained if the adhesive strength after thermocompression bonding is 9.0 N / 25 mm or less in tests using various adhesive tapes. confirmed.

10 ... Adhesive tape (back grind tape)
11 ... Base material 12 ... Adhesive layer 20 ... Chip group 21 ... Chip 30 ... Pickup tape 40 ... Ring frame 50 ... Peeling tape

Claims (4)

An adhesive tape containing a base material and an adhesive layer provided on one side thereof.
The pressure-sensitive adhesive layer comprises an energy ray-curable pressure-sensitive adhesive.
After a silicon wafer mirror surface is attached to the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is cured by irradiating it with energy rays, and further ^{thermocompression-bonded at a pressure of 0.5 N / cm 2} and 210 ° C. for 5 seconds, and then the adhesive strength at 23 ° C. is 9. Adhesive tape of 0.0N / 25mm or less. A back grind tape is attached to the front surface of the semiconductor wafer having grooves formed on the surface of the semiconductor wafer, the back surface is ground, and the semiconductor wafer is fragmented into semiconductor chips by the grinding, and then the fragmented chip group is formed. The adhesive tape according to claim 1, which is used as the backgrinding tape in a method for manufacturing a semiconductor device including a step of transferring to a pickup tape or an adhesive tape. A back grind tape is attached to the front surface of the semiconductor wafer having grooves formed on the surface of the semiconductor wafer, the back surface is ground, and the semiconductor wafer is fragmented into semiconductor chips by the grinding, and then the fragmented chip group is formed. A method for manufacturing a semiconductor device, which comprises a step of transferring to a pickup tape or an adhesive tape, wherein the adhesive tape according to claim 1 is used as the backgrinding tape. The adhesive tape according to claim 1, wherein a back grind tape is attached to the surface of the semiconductor wafer having grooves formed on the surface of the semiconductor wafer, the back surface is ground, and the semiconductor wafer is formed into a semiconductor chip by the grinding. Use as the backgrinding tape in a method for manufacturing a semiconductor device, which comprises a step of separating the pieces into individual pieces and then transferring the individualized pieces to a pickup tape or an adhesive tape.

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