TW202233778A - adhesive sheet - Google Patents

Abstract

Provided is an adhesive sheet which has an appropriate adhesiveness to a sealing resin that seals a semiconductor chip and to the semiconductor chip, and can be easily peeled off from the sealing resin, and in which it is difficult for adhesive residue to occur during peeling, and after peeling off the adhesive sheet, it is difficult to create a height difference between the semiconductor chip and the sealing resin. The adhesive sheet of the present invention comprises: a base material; and an adhesive layer disposed on at least one side of the base material, wherein the adhesive layer contains an acrylic adhesive, the amount of subduction of the adhesive sheet in an environment of 23 DEG C using TMA is 5 [mu]m or less, and the T2 relaxation time (T2s) of an S component of the adhesive layer by pulse NMR is 45 [mu]sec or less.

Description

adhesive sheet

The present invention relates to an adhesive sheet.

In recent years, in order to prevent damage to the semiconductor wafer, spread metal wiring, and the like when manufacturing a semiconductor component including a semiconductor wafer, an operation of sealing the semiconductor wafer with a resin is sometimes performed. In the resin sealing step, from the viewpoint of workability and the like, an operation of sealing a semiconductor wafer with a resin may be performed on an adhesive sheet. For example, a plurality of semiconductor chips are arranged on a specific adhesive sheet as a temporary fixing material, and the semiconductor chips are once sealed on the adhesive sheet to prevent the semiconductor chips from moving. Thereafter, in a specific subsequent step, the above-mentioned adhesive sheet is peeled off from the resin in which the semiconductor chip is sealed.

In the above-mentioned steps, if the conventional adhesive sheet is used, there is a problem that the adhesive remains on the structure when the adhesive sheet is peeled off from the structure including the sealing resin and the semiconductor wafer. In addition, the semiconductor wafer is pressed into the adhesive sheet during sealing, and as a result, after the adhesive sheet is peeled off, there is a problem that a level difference occurs between the semiconductor wafer and the sealing resin. Such a level difference may lead to defects such as insufficient protection of the semiconductor wafer and inability to form metal wirings. In addition, paste residues are also likely to occur due to this level difference. [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2001-308116 Patent Document 2: Japanese Patent Laid-Open No. 2001-313350

[Problems to be Solved by Invention]

The present invention is intended to solve the above-mentioned problems, and its object is to provide an adhesive sheet which has moderate adhesiveness to a sealing resin for sealing a semiconductor chip and a semiconductor chip, can be easily peeled off from the sealing resin, and is less likely to produce paste during peeling The agent remains, and the level difference between the semiconductor wafer and the sealing resin is less likely to occur after the adhesive sheet is peeled off. [Technical means to solve problems]

The adhesive sheet of the present invention includes a base material and an adhesive layer disposed on at least one side of the base material, the adhesive layer contains an acrylic adhesive, and the adhesive sheet uses TMA (Thermomechanical Analyzer, thermomechanical analyzer) The measured amount of sinking in a 23°C environment was 5 μm or less, and the T ₂ relaxation time (T _2s ) of the S component of the adhesive layer obtained by pulse NMR was 45 μsec or less. In one embodiment, 4-tert-butylphenyl glycidyl ether is dropped on the surface of the adhesive layer, and the thickness change rate of the adhesive layer is less than 160% after standing for 1 minute. In one embodiment, 4-tert-butylphenyl glycidyl ether is dropped on the surface of the adhesive layer, and after standing for 1 minute, the thickness change of the adhesive layer is less than 20 μm. In one embodiment, the adhesive layer contains an adhesive, and the adhesive includes a sp (Solubility Parameter) value of 18 (cal/cm ³ ) ^1/2 to 20 (cal/cm ³ ) ^1/2 base polymer. In one embodiment, the above-mentioned acrylic adhesive includes a cross-linked body of an acrylic polymer as a base polymer. In one embodiment, the above-mentioned acrylic adhesive includes an epoxy-based crosslinking agent. In one embodiment, the mixing amount of the epoxy-based crosslinking agent is 0.6 parts by weight to 15 parts by weight with respect to 100 parts by weight of the acrylic polymer. In one Embodiment, the said base material is a resin sheet which consists of resin whose glass transition temperature (Tg) is 25 degreeC or more. In one embodiment, the thickness of the substrate is 20% to 90% relative to the total thickness of the adhesive sheet. In one embodiment, the sinking amount of the above-mentioned adhesive sheet obtained by using TMA in a 145° C. environment is 1 μm˜35 μm. In one embodiment, the amount of nitrogen gas generated when the adhesive layer is heat-treated is 0.06% by weight to 1% by weight. In one embodiment, the above-mentioned adhesive sheet includes: the above-mentioned substrate, the above-mentioned adhesive layer arranged on one side of the substrate, and a second adhesive arranged on the opposite side of the substrate and the adhesive layer Floor. In one embodiment, the above-mentioned adhesive sheet is a temporary fixing material used in the resin sealing step of the semiconductor chip. In one Embodiment, the said adhesive sheet is used when hardening a sealing resin on the said adhesive sheet. [Effect of invention]

According to the present invention, it is possible to provide an adhesive sheet which has moderate adhesiveness to the sealing resin for sealing the semiconductor chip and the semiconductor chip, can be easily peeled off from the sealing resin, is less likely to produce paste residue during peeling, and can be used when the adhesive sheet is peeled off. After the material is peeled off, the level difference between the semiconductor wafer and the sealing resin is less likely to occur.

A. Outline of Adhesive Sheet FIG. 1 is a schematic cross-sectional view of an adhesive sheet according to an embodiment of the present invention. The adhesive sheet 100 includes a substrate 10 and an adhesive layer (first adhesive layer) 20 arranged on at least one side of the substrate 10 . The adhesive layer contains an acrylic adhesive.

The adhesive sheet of the present invention can be preferably used as a temporary fixing material when resin-sealing a semiconductor wafer. More specifically, in the adhesive sheet of the present invention, semiconductor chips are arranged on the adhesive layer of the adhesive sheet, the semiconductor chips are covered with resin (usually epoxy resin), and the sealing resin is cured by curing the sealing resin. The semiconductor wafer is sealed with resin, and can be used as a temporary fixing material for the semiconductor wafer at this time. After sealing the semiconductor wafer with resin, in specific subsequent steps (such as backside grinding of the sealing resin, patterning, bump formation, and dicing (dicing into wafers)), the above-mentioned adhesive sheet can be separated from the sealing resin and the semiconductor wafer. The constituent structures are peeled off. The epoxy equivalent of the sealing resin is, for example, 50 g/eq to 500 g/eq.

The sinking amount of the above-mentioned adhesive sheet obtained by using TMA in a 23°C environment is 5 μm or less. In addition, the T ₂ relaxation time (T _2s ) of the S component of the adhesive layer obtained by pulse NMR was 45 μsec or less. With the adhesive sheet having these characteristics, after the semiconductor wafer is sealed with resin on the adhesive sheet, the level difference between the semiconductor wafer and the sealing resin is prevented when the adhesive sheet is peeled off.

It is considered that the important reasons for the level difference between the semiconductor wafer and the sealing resin are that the components of the adhesive layer are transferred to the sealing resin, and the semiconductor wafer is buried in the adhesive layer due to the force applied to the semiconductor wafer during resin sealing. A more detailed description is given using FIG. 2(a). FIG. 2( a ) shows an example of the case where the conventional adhesive sheet 100 ′ is used in resin sealing of semiconductor wafers. The adhesive sheet 100' has an adhesive layer, and the outer surface of the adhesive layer serves as an attachment surface. When sealing the semiconductor wafer with resin, the semiconductor wafer 1 (a-i) is firstly attached to the adhesive sheet 100'. Thereafter, the composition 2' containing a monomer as a precursor of the sealing resin 2 is coated in a manner of sealing the semiconductor wafer 1 (a-ii); thereafter, the composition 2' is hardened (a-iii). In addition, as said composition, the composition containing a naphthalene type difunctional epoxy resin (epoxy equivalent: 144) is used, for example. Then, in a specific subsequent step, the adhesive sheet 100 ′ (a-iv) is peeled off from the structure A including the semiconductor wafer 1 and the sealing resin 2 . In this operation process, the step (a-ii) and the step (a-iii) represent component transfer between the adhesive layer and the sealing resin, and the sealing resin forms a mixture of the adhesive component and the sealing resin component. Mutually. When the mixed phase is formed, when the adhesive sheet is peeled off, the mixed phase is destroyed, and a part of the sealing resin is peeled off together with the adhesive sheet, resulting in a level difference between the semiconductor wafer and the sealing resin. Moreover, in the step represented by (a-ii) and the step represented by (a-iii), the force applied to the semiconductor chip causes a part of the semiconductor chip to be buried in the adhesive layer. The embedding of the semiconductor chip into the adhesive layer is also an important cause of the level difference between the semiconductor chip and the sealing resin.

In the present invention, by setting the amount of sinking in a 23° C. environment obtained by using TMA to 5 μm or less, it is possible to prevent the transfer of the components of the adhesive layer into the sealing resin and the embedding of the semiconductor wafer into the adhesive layer. (especially the embedding of the semiconductor wafer into the adhesive layer) (FIG. 2(b)). In addition, by setting the T ₂ relaxation time (T _2s ) of the S component of the adhesive layer obtained by pulsed NMR to 45 μsec or less, the transfer of the adhesive layer component to the sealing resin and the transfer of the semiconductor wafer to the adhesive can be prevented Embedding within the layer (especially the transfer of the adhesive layer components into the sealing resin) (Fig. 2(b)).

The sinking amount of the adhesive sheet obtained by using TMA in a 23° C. environment is preferably 4 μm or less, more preferably 3.5 μm, and still more preferably 3 μm or less. Within such a range, the effect of the present invention is remarkable. The amount of sinking in the 23°C environment obtained by using TMA of the adhesive sheet is preferably as small as possible, and the lower limit is preferably 0.1 μm (preferably 0.01 μm). For example, by appropriately adjusting the composition of the adhesive constituting the adhesive layer and the structure (especially the crosslinking density) of the base polymer contained in the adhesive, the sinking amount in the above-mentioned range can be achieved.

"The amount of sinking in the 23°C environment obtained by using TMA of the adhesive sheet" means that the probe was brought into contact with the adhesive layer (the first adhesive layer) using a thermomechanical analyzer, and the sinking occurred after 60 minutes. quantity. The measurement conditions were set as probe: needle penetration, nitrogen flow rate: 50.0 ml/min, and pressure load: 0.01 N. In addition, in the case where the adhesive sheet has an adhesive layer only on one side of the base material (that is, when there is no second adhesive layer described later), the base material is opposite to the adhesive layer (first adhesive layer) After the standard adhesive layer was formed on one side, the above-mentioned measurement was carried out. The standard adhesive layer is an adhesive layer with a thickness of 45 μm formed by coating the composition for forming an adhesive layer. The composition for forming an adhesive layer is an acrylic copolymer (2-ethylhexyl acrylate (2EHA) , copolymer of ethyl acrylate (EA), methyl methacrylate (MMA) and 2-hydroxyethyl acrylate (HEA), 2EHA structural unit: EA structural unit: MMA structural unit: HEA structural unit=30:70: 5:5 (weight ratio) (molecular weight (Mw=450,000))) 100 parts by weight, adhesion imparting agent (manufactured by YASUHARA Chemicals, trade name "Mighty Ace G125") 10 parts by weight, isocyanate-based crosslinking agent (Tosoh Corporation) It was obtained by mixing 2 parts by weight of heat-expandable microspheres (manufactured by Matsumoto Oil Pharmaceutical Co., Ltd., trade name "Matsumoto Microsphere F-190D"), and toluene.

The sinking amount of the adhesive sheet obtained by using TMA in an environment of 145° C. is preferably 1 μm to 35 μm, more preferably 1 μm to 34 μm, and more preferably 2 μm to 34 μm. Within such a range, the effect of the present invention is remarkable. Moreover, even if it experiences a high temperature environment (for example, the heat processing environment at the time of resin sealing), a semiconductor chip is prevented from being buried in the adhesive layer.

3 is a schematic cross-sectional view of an adhesive sheet according to another embodiment of the present invention. The adhesive sheet 200 further includes a second adhesive layer 30 on the opposite side of the base material 10 from the adhesive layer 20 . That is, the adhesive sheet 200 includes the adhesive layer 20 , the base material 10 , and the second adhesive layer 30 in this order. By providing the 2nd adhesive bond layer 30, when performing resin sealing on a stage, the 2nd adhesive bond layer 30 side is stuck to this stage, and the adhesive sheet 200 can be arrange|positioned with good fixability.

In one embodiment, the second adhesive layer includes thermally expandable microspheres. The heat-expandable microspheres can expand at a specific temperature. By heating the adhesive layer containing such heat-expandable microspheres to a predetermined temperature or higher, the heat-expandable microspheres expand, resulting in unevenness on the adhesive surface (ie, the surface of the second adhesive layer), and the adhesive force decreases or disappears. When the second adhesive layer containing the thermally expandable microspheres is formed, the adhesiveness required when the adhesive sheet is fixed (for example, to a stage) can be exhibited, and when the adhesive sheet is peeled off (for example, peeled off from the stage) It exhibits good peelability due to the decrease or disappearance of the heating adhesive force.

The adhesive force A of the adhesive sheet of the present invention at 23° C. when the adhesive layer is attached to polyethylene terephthalate is preferably 0.05 N/20 mm to 1 N/20 mm, more preferably 0.1 N/20 mm to 10 N/20 mm, more preferably 0.1 N/20 mm to 5 N/20 mm, more preferably 0.2 N/20 mm to 2 N/20 mm, most preferably 0.2 N/20 mm ~1N/20mm. Within such a range, an adherend (eg, a semiconductor wafer) can be favorably fixed, and an adhesive sheet can be obtained that has less paste residue when peeled off. Furthermore, in this specification, the so-called "adhesive force at 23°C when the adhesive layer is attached to polyethylene terephthalate" refers to the following adhesive force: on the polyethylene terephthalate film (Thickness 25 μm) Laminate the adhesive layer of the adhesive sheet (width 20 mm × length 140 mm) (lamination conditions: roll back and forth with a 2 kg roller for 1 time), and place it at an ambient temperature of 23 ℃ for 30 minutes Then, the sample was subjected to a tensile test (peeling speed: 300 mm/min, peeling angle 180°) and measured.

The shear adhesion force B at 150° C. of the adhesive sheet of the present invention when the adhesive layer is attached to the silicon wafer is preferably 500 g or more, more preferably 700 g to 1500 g, and more preferably 800 g to 1200 g . Within this range, the cohesive force of the adhesive is high, and even at a high temperature (for example, a heating step for hardening the sealing resin), it has a good adhesive force, and can prevent the adhesive sheet disposed on the adhesive sheet from being stuck. A body, such as a semiconductor wafer, is displaced. The shear adhesion force can be measured by the following method: after vertically attaching a mirror surface of a silicon wafer (size: 5 mm × 5 mm) on the adhesive layer without touching the corner of the wafer, heating at 130°C for 30 minutes The silicon wafer is adhered to the surface of the adhesive, and then, at the measurement temperature (150°C in the case of the shear adhesion force B measurement), an external force is applied in a direction horizontal to the wafer at a shear rate of 500 μm/sec. A load-displacement curve is obtained from which the maximum failure load is read. As a measuring apparatus, for example, dage4000 manufactured by Nordson Corporation is used. In addition, in the above measurement, the measurement terminal can be located at a position 250 μm higher than the surface of the adhesive layer.

The shear adhesion force of the adhesive sheet of the present invention at 190° C. when the adhesive layer is attached to the silicon wafer is preferably 300 g-1000 g, more preferably 350 g-750 g, and more preferably 400 g-600 g g. Within such a range, when the above-mentioned pressure-sensitive adhesive sheet includes a second pressure-sensitive adhesive layer containing heat-expandable microspheres, when the second pressure-sensitive adhesive layer side is made to express releasability, that is, heating is performed so that the When the heat-expandable microspheres expand, the adherend on the adhesive layer can be well fixed.

The thickness of the adhesive sheet of the present invention is preferably 3 μm to 300 μm, more preferably 5 μm to 150 μm, and still more preferably 10 μm to 100 μm.

B. Adhesive layer The above-mentioned adhesive layer is composed of an adhesive including a base polymer. As described above, the T ₂ relaxation time (T _2s ) of the S component of the adhesive layer obtained by pulse NMR is 45 μsec or less. The relaxation time refers to the time elapsed for the atoms (groups) in the excited state to return to the ground state after irradiating a suitable energy to excite the atoms to be measured in pulsed NMR measurement. Which excited state an atom (cluster) becomes can be controlled by the irradiation energy value or irradiation time. In addition, when the atoms (groups) in the excited state return to the ground state, it is known that there are various energy relaxation mechanisms, and the relaxation time is determined according to the relaxation mechanism (for example, "The latest NMR introduction for chemists", Chemist (1997) )). The inventors of the present invention excited the ¹ H atom of the acrylic adhesive (substantially the acrylic polymer contained in the adhesive) under the following conditions, measured the relaxation behavior thereafter, and analyzed the measured values. As a result, it was found that the S component (T _2s ) of the T ₂ relaxation time can be used to understand the degree of cross-linking of the base polymer (representatively acrylic polymer) contained in the adhesive constituting the adhesive layer. information on molecular motion, and found that the above effect can be obtained by specifying the S component (T _2s ) of the T ₂ relaxation time. If T _2s is short, it means that the molecular motion related to the degree of cross-linking of the base polymer is restricted, that is, it means that the degree of freedom of movement of the polymer as a whole is also reduced due to further cross-linking. In the acrylic adhesive in this state, the gap between the base polymers is small, and the transfer of the components of the adhesive layer to the sealing resin and the transfer of the low molecular weight components contained in the sealing resin to the adhesive layer are suppressed. As a result, after sealing the semiconductor wafer with resin on the adhesive sheet, it is possible to prevent the occurrence of a level difference between the semiconductor wafer and the sealing resin when the adhesive sheet is peeled off.

The T ₂ relaxation time (T _2s ) of the S component of the adhesive layer obtained by pulsed NMR is preferably 10 μsec to 50 μsec, more preferably 10 μsec to 45 μsec, and more preferably 10 μsec to 40 μsec. Within such a range, the above-mentioned effects are remarkable.

The T ₂ relaxation time (T _2s ) of the S component obtained by pulsed NMR can be obtained as follows: 100 mg of the adhesive layer is taken as a measurement sample, and a T 2 relaxation curve is obtained by measuring the T ₂ relaxation curve by the solid echo method. ₂ The relaxation curve is substituted into the following equation (1). M(t)=α・exp(-(1/Wa)(t/T _2s ) ^Wa ) +β・exp(-(1/Wa)(t/T _2L ) ^Wa )・・・(1) M(t ): Free induced decay α: Proton ratio (%) of the component with a shorter relaxation time (S component) T _2s : T ₂ relaxation time of the S component (msec) β: Component with a longer relaxation time (L component) ) proton ratio (%) T _2L : T ₂ relaxation time of the L component (msec) t: Observation time (msec) Wa: shape factor (=1) The measurement conditions in the above measurement are as follows.・90° pulse width: 2.1 μsec ・Repeat time: 1 sec ・Number of accumulations: 32 ・Measurement temperature: 30℃

4-tert-butylphenyl glycidyl ether is dripped on the surface of the above-mentioned adhesive layer, and after standing for 1 minute, the thickness change rate of the adhesive layer is preferably 160% or less, more preferably 150% or less, and more preferably It is 120% or less, and it is especially preferable that it is 100% or less. The cross-linking density of the adhesive layer within this range of the thickness change rate is high, which prevents the transfer of components between the adhesive layer and the sealing resin. A level difference occurs between the semiconductor wafer and the sealing resin during peeling. The thickness change rate is preferably as small as possible, and the lower limit thereof is, for example, 20% (preferably 10%). The said thickness change rate (and the thickness change amount mentioned later) can be set to the said range by suitably selecting the base polymer (representatively an acrylic polymer) contained in an acrylic adhesive, for example. For example, by using an acrylic polymer having a large number of carbon atoms (for example, 4 or more, preferably 8 or more), an adhesive layer with a small thickness change rate (and thickness change amount described later) can be formed. The above-mentioned thickness change rate is obtained by the following method: drop a specific amount (using a syringe with a diameter of 22 mm, 0.02 g) of 4-tert-butylphenyl glycidyl ether on the surface of the adhesive layer, and at 23 ° C, 50 Place for 1 minute under the environment of %RH, after wiping off 4-tert-butylphenyl glycidyl ether, from the thickness (Dt) of the drop-dropping position and the thickness (It) of the position before the above-mentioned drop-dropping operation, according to Formula: (Dt-It)/It is calculated.

4-tert-butylphenyl glycidyl ether is added dropwise on the surface of the above-mentioned adhesive layer, and after standing for 1 minute, the thickness change of the adhesive layer is preferably 20 μm or less, more preferably 15 μm or less, and more preferably It is 10 micrometers or less, More preferably, it is 6 micrometers or less. The cross-linking density of the adhesive layer with the thickness variation in this range is high, which prevents the transfer of components between the adhesive layer and the sealing resin. As a result, after sealing the semiconductor wafer with the resin on the adhesive sheet, A level difference occurs between the semiconductor wafer and the sealing resin during peeling. The thickness variation is preferably as small as possible, and the lower limit thereof is, for example, 3 μm (preferably 1 μm). The said thickness change amount is calculated|required from the said Dt and It based on an arithmetic formula: Dt-It.

The gel fraction of the adhesive layer is preferably 75% or more, more preferably 85% or more, and still more preferably 90% or more. Within such a range, the molecular motion of the base polymer is well restrained by crosslinking, and an adhesive layer that prevents component transfer between the adhesive layer and the sealing resin can be obtained. The higher the gel fraction of the adhesive layer, the better, and the upper limit is, for example, 99.5%. In addition, the gel fraction was calculated|required by (dry weight after immersion/dry weight before immersion)*100 after immersing the crosslinked adhesive in ethyl acetate for 7 days and drying.

The amount of nitrogen gas generated when the adhesive layer is heat-treated is preferably 0.06 to 1.0% by weight, more preferably 0.06 to 0.9% by weight. When the amount of nitrogen gas generated during the heat treatment of the adhesive layer is within this range, the acrylic adhesive fully exerts its cohesive force and suppresses the transfer of low molecular weight components of the sealing resin into the adhesive layer, thereby preventing the formation of sticking. The mixed layer of the agent layer component and the sealing resin component is less likely to have a step difference at the interface between the semiconductor chip and the sealing resin. The amount of nitrogen gas in the adhesive layer when it is heated is obtained by the following method: collect 2 mg of the adhesive layer, put it on a ceramic plate, and weigh it with a microbalance. Heating was performed under the condition of 900°C, and the amount of generated nitrogen gas was determined using a TN (total trace nitrogen analyzer) apparatus. Each condition in the measurement can be set as follows.・Carrier gas: O ₂ (300 mL/min), Ar (300 mL/min) ・Standard sample: Pyridine/toluene solution ・Detector: Decompression chemiluminescence detector ・Range: High concentration

The thickness of the above-mentioned adhesive layer is preferably 1 μm to 50 μm, more preferably 3 μm to 30 μm, and still more preferably 5 μm to 20 μm. Within such a range, an adhesive sheet that does not easily embed the semiconductor wafer in the resin can be obtained even under pressure during the sealing step.

The elastic modulus of the adhesive layer measured by the nanoindentation method at 25°C is preferably less than 100 MPa, more preferably 0.1 MPa to 50 MPa, and still more preferably 0.1 MPa to 10 MPa. Within such a range, an adhesive sheet having moderate adhesive force can be obtained. The so-called elastic modulus measured by the nanoindentation method refers to the continuous measurement of the load applied to the indenter when the indenter is pressed into the sample and the indentation during the entire process including loading and unloading. Depth, modulus of elasticity obtained from the obtained load-load-indentation depth curve. In this specification, the so-called elastic modulus measured by nanoindentation method refers to the measurement obtained by the above method under the measurement conditions of load: 1 mN, load/unload speed: 0.1 mN/s, holding time: 1s modulus of elasticity.

The tensile modulus of elasticity of the adhesive layer at 25°C is preferably less than 100 MPa, more preferably 0.1 MPa to 50 MPa, and still more preferably 0.1 MPa to 10 MPa. Within such a range, an adhesive sheet having moderate adhesive force can be obtained. In addition, the tensile modulus of elasticity can be measured according to JIS K 7161:2008.

The probe tack value of the adhesive layer is preferably 50 N/5 mmϕ or higher, more preferably 75 N/5 mmϕ or higher, and more preferably 100 N/5 mmϕ or higher. Within such a range, positional displacement of the adherend (eg, semiconductor wafer) arranged on the adhesive sheet can be prevented. The measurement conditions of the probe viscosity value were set as follows: probe processing speed: 30 mm/min, test speed: 30 mm/min, contact load: 100 gf, contact retention time: 1 second, and probe area: 5 mmϕSUS.

The sp value of the above-mentioned base polymer is preferably 10(cal/cm ³ ) ^1/2 to 30(cal/cm ³ ) ^1/2 , more preferably 15(cal/cm ³ ) ^1/2 to 25(cal/cm 3 ) 1/2 cm ³ ) ^1/2 , more preferably 18(cal/cm ³ ) ^1/2 to 20(cal/cm ³ ) ^1/2 . Within such a range, the transfer of components between the adhesive layer and the sealing resin is preferably prevented.

(acrylic adhesive) As the above-mentioned acrylic adhesive, for example, an acrylic polymer (homopolymer or copolymer) obtained by using one or more (meth)acrylic acid alkyl esters as a monomer component can be mentioned as a prepolymer The cross-linked body of the prepolymer is used as the acrylic adhesive of the base polymer, etc. In addition, in this specification, the so-called "base polymer" contained in the acrylic adhesive in the adhesive layer means a polymer formed by crosslinking a prepolymer (uncrosslinked polymer). In one embodiment, the above-mentioned base polymer has a cross-linked structure based on an acrylic polymer and an epoxy cross-linking agent.

Specific examples of the above-mentioned alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and isopropyl (meth)acrylate. , butyl (meth)acrylate, isobutyl (meth)acrylate, 2-butyl (meth)acrylate, 3-butyl (meth)acrylate, amyl (meth)acrylate, (meth)acrylate Hexyl acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, ( isononyl meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, (meth)acrylate ) Tridecyl acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate C1-20 alkyl esters of (meth)acrylates such as octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among them, alkyl (meth)acrylates having a linear or branched alkyl group having a carbon number of 4 to 20 (more preferably 6 to 20, particularly preferably 8 to 18) are preferred, and (meth)acrylates are more preferred. 2-ethylhexyl meth)acrylate.

In one embodiment, an alkyl (meth)acrylate having a linear or branched alkyl group having 4 or more carbon atoms (preferably 8 or more) is used. When an alkyl (meth)acrylate is used, it is preferable to prevent the transfer of components between the adhesive layer and the sealing resin.

In order to improve cohesion, heat resistance, crosslinking properties, etc., the above-mentioned acrylic polymer (prepolymer) may contain other monomer components which can be copolymerized with the above-mentioned alkyl (meth)acrylate, if necessary. the unit. Examples of such monomer components include carboxyl-containing groups such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Monomers; anhydride monomers such as maleic anhydride and itaconic anhydride; hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, (meth)acrylic acid Hydroxyhexyl, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl methacrylate, etc. body; styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate , (meth)acryloyloxynaphthalenesulfonic acid and other monomers containing sulfonic acid groups; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (methyl) (N-substituted) amide monomers such as acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, etc.; (meth)acrylate amine Aminoalkyl (meth)acrylate monomers such as ethyl ethyl ester, N,N-dimethylaminoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate, etc.; ( (meth)acrylic acid alkoxyalkyl ester monomers such as methoxyethyl meth)acrylate and ethoxyethyl (meth)acrylate; N-cyclohexylmaleimide, N- Isopropyl maleimide, N-lauryl maleimide, N-phenylmaleimide and other maleimide monomers; N-methyl Iconimide, N-Ethyl Iconimide, N-Butyl Iconimide, N-Octyl Iconimide, N-2-Ethylhexyl Iconimide, N -Iconimide monomers such as Cyclohexyl Iconimide, N-Lauryl Iconimide, etc.; Butadiimide such as meth)acryloyl-6-oxyhexamethylene butadiimide, N-(meth)acryloyl-8-oxyoctamethylene butadiimide, etc. Monomers; vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperidone, vinyl Ethylene such as pyridine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxyamide, styrene, α-methylstyrene, N-vinylcaprolactam cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy-containing acrylic monomers such as glycidyl (meth)acrylate; polyethylene glycol (meth)acrylate, ( Glycol acrylate monomers such as polypropylene glycol meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; tetrahydrofurfuryl (meth)acrylate , fluorinated (meth)acrylate, (meth)acrylate silicone ester and other acrylate monomers containing heterocycles, halogen atoms, silicon atoms, etc.; hexanediol di(meth)acrylate, (poly) Ethylene glycol bis(methyl) Acrylates, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol Multifunctional monomers such as tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate; isoprene, butadiene, Olefin-based monomers such as isobutylene; vinyl ether-based monomers such as vinyl ether, etc. These monomer components may be used alone or in combination of two or more.

In one embodiment, the above-mentioned acrylic polymer (prepolymer) further includes a glass transition temperature (Tg) derived from the formation of a homopolymer of -5°C to 150°C (preferably 50°C to 150°C, more It is preferably the structural unit a of the monomer of 80°C to 120°C). If such a structural unit a is included, the molecular motion of the acrylic polymer is restricted, and an acrylic polymer whose T ₂ relaxation time (T _2s ) of the S component obtained by pulse NMR can be better adjusted can be obtained. Moreover, an adhesive sheet excellent in low-temperature adhesiveness can be obtained. The content of the above-mentioned structural unit a is preferably 0.1% by weight to 20% by weight, more preferably 1% by weight to 10% by weight, and particularly preferably 1.5% by weight to 8% by weight relative to all the structural units constituting the acrylic polymer. , the best is 3% by weight to 6% by weight.

As a monomer whose glass transition temperature (Tg) is -5°C to 150°C, for example, 2-hydroxyethyl acrylate (Tg: -3°C), 2-hydroxyethyl methacrylate (Tg: 77°C) can be mentioned. ), acrylic acid (Tg: 102°C), cyclohexyl methacrylate (Tg: 83°C), dicyclopentyl acrylate (Tg: 120°C), dicyclopentyl methacrylate (Tg: 175°C), acrylic acid Isocyanate (Tg: 94°C), isocyanate methacrylate (Tg: 150°C), tert-butyl methacrylate (Tg: 118°C), methyl methacrylate (Tg: 105°C), benzene Ethylene (Tg: 80°C), acrylonitrile (Tg: 97°C), N-acrylomorpholine (Tg: 145°C), and the like. Among them, methyl methacrylate improves the transparency of the adhesive layer, so it is preferable to improve the visibility of the adherend during processing, and acrylic acid strongly adheres to the adherend by intermolecular interaction, so When strong adhesion is required, hydroxyethyl acrylate and various cross-linking agents show higher reactivity, so it is better in controlling the relaxation time.

In one embodiment, the above-mentioned acrylic polymer (prepolymer) further includes a structural unit derived from a hydroxyl group-containing monomer. The content of the structural unit derived from the hydroxyl group-containing monomer is preferably 0.1% by weight to 20% by weight, more preferably 0.5% by weight to 10% by weight, particularly preferably 1 % by weight to 7% by weight.

The said acrylic adhesive may contain arbitrary appropriate additives as needed. As the additive, for example, a crosslinking agent, an adhesion imparting agent, a plasticizer (for example, a trimellitic acid ester-based plasticizer, a pyromellitic acid ester-based plasticizer, etc.), pigments, dyes, fillers, etc. may be mentioned. agent, anti-aging agent, conductive material, antistatic agent, ultraviolet absorber, light stabilizer, peeling regulator, softener, surfactant, flame retardant, antioxidant, etc.

Examples of the crosslinking agent contained in the acrylic adhesive include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, and urea-based crosslinking agents. agent, metal alkoxide-based cross-linking agent, metal chelate-based cross-linking agent, metal salt-based cross-linking agent, carbodiimide-based cross-linking agent, oxazoline-based cross-linking agent, aziridine-based cross-linking agent Linking agent, amine crosslinking agent, etc.

In one embodiment, the compounding amount of the crosslinking agent relative to the carboxyl group of the acrylic polymer (prepolymer) is preferably 0.08 mol equivalent to 2 mol equivalent, more preferably 0.1 mol equivalent to 1 mol equivalent equivalent. Within this range, an acrylic adhesive with a high crosslinking density can be formed, and the transfer of components between the adhesive layer and the sealing resin can be preferably prevented. Here, the compounding amount of the crosslinking agent means the content of the crosslinking agent before the crosslinking of the acrylic polymer.

Specific examples of the above-mentioned isocyanate-based crosslinking agent contained in the above-mentioned acrylic adhesive include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; cyclopentylene diisocyanate, Cyclohexylene diisocyanate, isophorone diisocyanate and other alicyclic isocyanates; 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and other aromatic isocyanates ; Trimethylolpropane/toluene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry, trade name "Coronate L"), trimethylolpropane/hexamethylene diisocyanate trimer adduct ( Isocyanate adducts such as Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), isocyanurate of hexamethylene diisocyanate (Nippon Polyurethane Industry, trade name "Coronate HX") and the like. The compounding amount of the isocyanate-based crosslinking agent can be set to any suitable amount according to the required adhesive force, with respect to 100 parts by weight of the acrylic polymer, typically 0.1 part by weight to 20 parts by weight, more preferably 1 part by weight ~10 parts by weight. Within such a range, an adhesive sheet with less residual carboxyl groups of components in the adhesive layer can be obtained. Here, the compounding amount of the crosslinking agent means the content of the crosslinking agent before the crosslinking of the acrylic polymer.

In one embodiment, as the above-mentioned cross-linking agent, an epoxy-based cross-linking agent is preferably used. When an epoxy-based crosslinking agent is used, an adhesive sheet which can preferably reduce the level difference between the semiconductor wafer and the sealing resin can be obtained. In addition, an adhesive layer with high cohesive force can be formed, and positional displacement of the adherend can be prevented more effectively.

As the epoxy-based crosslinking agent contained in the acrylic adhesive, for example, N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1, 3-bis(N,N-glycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (Kyoeisha Chemical Co., Ltd. manufactured by the company, trade name "Epolight 1600"), neopentyl glycol diglycidyl ether (manufactured by Kyeisha Chemical Co., Ltd., trade name "Epolight 1500NP"), ethylene glycol diglycidyl ether (manufactured by Kyeisha Chemical Co., Ltd., Trade name "Epolight 40E"), propylene glycol diglycidyl ether (manufactured by Kyeisha Chemical Co., Ltd., trade name "Epolight 70P"), polyethylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "EPIOL E-400" ”), polypropylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name “EPIOL P-200”), sorbitol polyglycidyl ether (manufactured by Nagase chemteX, trade name “DENACOL EX-611”), glycerin polyglycidyl Glyceryl ether (manufactured by Nagase chemteX, trade name "DENACOL EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase chemteX, trade name "DENACOL EX-512"), sorbitan polyglycidyl ether Glycidyl ether, trimethylolpropane polyglycidyl ether, diglycidyl adipate, diglycidyl phthalate, triglycidyl tris(2-hydroxyethyl) isocyanurate, isophthalic acid Phenol diglycidyl ether, bisphenol-S-diglycidyl ether, epoxy resins having two or more epoxy groups in the molecule, and the like. The compounding amount of the epoxy-based crosslinking agent can be set to any suitable amount according to the required adhesive force, with respect to 100 parts by weight of the acrylic polymer, typically 0.01 parts by weight to 50 parts by weight, more preferably 0.6 parts by weight parts by weight to 15 parts by weight, more preferably 2 parts by weight to 13 parts by weight, particularly preferably 3 parts by weight to 10 parts by weight. Within such a range, an adhesive sheet with less residual carboxyl groups of components in the adhesive layer can be obtained. Here, the compounding amount of the crosslinking agent means the content of the crosslinking agent before the crosslinking of the acrylic polymer.

In one embodiment, an N atom-containing crosslinking agent is used as the epoxy-based crosslinking agent. If a crosslinking agent containing N atoms is used, it is advantageous in that the crosslinking reaction is accelerated by the action of a catalyst, and the adhesive is easily gelled.

Any suitable adhesion-imparting agent can be used as the above-mentioned adhesion-imparting agent contained in the above-mentioned acrylic adhesive. As the adhesion imparting agent, for example, an adhesion imparting resin can be used. Specific examples of the adhesion-imparting resins include rosin-based adhesion-imparting resins (for example, unmodified rosin, modified rosin, rosin phenol-based resins, rosin ester-based resins, etc.), terpene-based adhesion-imparting resins (for example, terpenes). olefin-based resin, terpene-phenol-based resin, styrene-modified terpene-based resin, aromatic-modified terpene-based resin, hydrogenated terpene-based resin), hydrocarbon-based adhesion-imparting resin (such as aliphatic hydrocarbon resin, aliphatic Cyclic hydrocarbon resins, aromatic hydrocarbon resins (such as styrene resins, xylene resins, etc.), aliphatic-aromatic petroleum resins, aliphatic-alicyclic petroleum resins, hydrogenated hydrocarbon resins, benzos Furan-based resins, benzofuran-indene-based resins, etc.), phenol-based adhesion-imparting resins (such as alkylphenol-based resins, xylaldehyde-based resins, resole, novolak, etc.), ketone-based adhesion-imparting resins, polyphenolic Amine based adhesion imparting resin, epoxy based adhesion imparting resin, elastic system adhesion imparting resin, etc. Among them, rosin-based tackifying resins, terpene-based tackifying resins, or hydrocarbon-based tackifying resins (styrene-based resins, etc.) are preferred. The adhesion imparting agent may be used alone or in combination of two or more. The addition amount of the adhesion imparting agent is preferably 5 parts by weight to 100 parts by weight, more preferably 8 parts by weight to 50 parts by weight, relative to 100 parts by weight of the base polymer.

It is preferable to use a resin with a relatively high softening point or glass transition temperature (Tg) as the above-mentioned adhesion imparting resin. If a resin with a high softening point or glass transition temperature (Tg) is used, an adhesive layer that can exhibit high adhesion even in a high temperature environment (eg, in a high temperature environment such as processing during sealing of semiconductor wafers) can be formed. The softening point of the adhesion imparting agent is preferably 100°C to 180°C, more preferably 110°C to 180°C, and still more preferably 120°C to 180°C. The glass transition temperature (Tg) of the adhesion imparting agent is preferably 100°C to 180°C, more preferably 110°C to 180°C, and still more preferably 120°C to 180°C.

It is preferable to use a low-polarity adhesion-imparting resin as the above-mentioned adhesion-imparting resin. If a low-polarity adhesion-imparting resin is used, an adhesive layer with low affinity with the sealing material can be formed. Examples of low-polarity adhesion-imparting resins include aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aromatic hydrocarbon resins (eg, styrene-based resins, xylene-based resins, etc.), aliphatic/aromatic Hydrocarbon-based adhesion imparting resins such as family-based petroleum resins, aliphatic/alicyclic petroleum resins, and hydrogenated hydrocarbon resins. Among them, an adhesion imparting agent having 5 to 9 carbon atoms is preferable. The reason for this is that such an adhesion-imparting agent is not only low in polarity, but also has excellent compatibility with acrylic polymers, does not undergo phase separation in a wide temperature range, and can form an adhesive layer with excellent stability.

The acid value of the adhesion-imparting resin is preferably 40 or less, more preferably 20 or less, and still more preferably 10 or less. Within such a range, an adhesive layer having a low affinity with the sealing material can be formed. The hydroxyl value of the adhesion-imparting resin is preferably 60 or less, more preferably 40 or less, and still more preferably 20 or less. Within such a range, an adhesive layer having a low affinity with the sealing material can be formed.

C. Substrates As the above-mentioned substrates, for example, resin sheets, non-woven fabrics, paper, metal foils, woven fabrics, rubber sheets, foamed sheets, and laminates thereof (especially those containing resin sheets can be exemplified) laminate), etc. As resin constituting the resin sheet, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyimide (PI) ), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluorine-based resin, polyether ether ketone (PEEK), etc. Examples of non-woven fabrics include non-woven fabrics made of natural fibers having heat resistance, such as non-woven fabrics including Manila hemp, and synthetic resin non-woven fabrics such as polypropylene resin non-woven fabrics, polyethylene resin non-woven fabrics, and ester-based resin non-woven fabrics. As metal foil, copper foil, stainless steel foil, aluminum foil, etc. are mentioned. As paper, Japanese paper, kraft paper, etc. are mentioned.

In one embodiment, as the base material, a resin sheet composed of a resin having a glass transition temperature (Tg) of 25°C or higher (preferably 40°C or higher, more preferably 50°C or higher) is preferably used. If such a resin sheet is used, the shape of the base material is maintained even under heating during the sealing step, and the semiconductor wafer is prevented from being embedded in the resin. As resin which comprises such a resin sheet, a polyethylene terephthalate, a polyimide, polyethylene naphthalate, etc. are mentioned, for example.

The thickness of the above-mentioned base material can be set to any suitable thickness according to the required strength, flexibility, and purpose of use. The thickness of the substrate is preferably 1000 μm or less, more preferably 25 μm to 1000 μm, further preferably 40 μm to 500 μm, particularly preferably 60 μm to 300 μm, and most preferably 80 μm to 250 μm. In one embodiment, a substrate with a thickness of 25 μm or more is used. If such a base material is used, the shape of the base material is maintained even under pressure during the sealing step, and the semiconductor chip is prevented from being buried in the adhesive layer.

In one embodiment, the thickness of the base material is 20%-90% (preferably 20%-89%, more preferably 20%-88%) relative to the total thickness of the adhesive sheet. Within such a range, the semiconductor wafer is prevented from being buried in the adhesive layer.

The above-mentioned base material may also be subjected to surface treatment. As the surface treatment, for example, corona treatment, chromic acid treatment, ozone exposure, flame exposure, high voltage electric shock exposure, ionizing radiation treatment, treatment of coating a primer layer, etc. may be mentioned.

As the above-mentioned organic coating material, for example, the material described in Plastic Hard Coating Material II (CMC Publishing, (2004)) can be exemplified. Preferably, urethane-based polymers are used, and more preferably, polyacrylate urethane, polyester urethane, or these precursors are used. The reason is that the coating and coating on the substrate are simple, and there are many kinds of industrial products to choose from, and the acquisition cost is low. The urethane-based polymer is, for example, a polymer comprising a reaction mixture of an isocyanate monomer and an alcoholic hydroxyl group-containing monomer (eg, a hydroxyl group-containing acrylic compound or a hydroxyl group-containing ester compound). The organic coating material may also contain chain extenders such as polyamines, anti-aging agents, oxidation stabilizers, etc. as optional additives. The thickness of the organic coating is not particularly limited, for example, it is preferably about 0.1 μm to 10 μm, preferably about 0.1 μm to 5 μm, and more preferably about 0.5 μm to 5 μm.

D. 2nd adhesive layer The said 2nd adhesive layer can be an adhesive layer which consists of any suitable adhesive. In one embodiment, as described above, the second adhesive layer further includes thermally expandable microspheres.

The adhesive contained in the second adhesive layer may be a curable adhesive (eg, an active energy ray curable adhesive) or a pressure-sensitive adhesive. As a pressure-sensitive adhesive, an acrylic adhesive, a rubber-type adhesive, etc. are mentioned, for example. Details of the adhesive contained in the second adhesive layer can be referred to, for example, the description of Japanese Patent Laid-Open No. 2018-009050. The full text of the publication is incorporated by reference in this specification.

As the thermally expandable microspheres, any suitable thermally expandable microspheres can be used as long as the microspheres can be expanded or foamed by heating. As the above-mentioned thermally expandable microspheres, for example, microspheres formed by enclosing a substance that is easily expandable by heating in an elastic shell can be used. Such heat-expandable microspheres can be produced by any appropriate method, for example, a coacervation method, an interfacial polymerization method, or the like.

Examples of substances that can be easily expanded by heating include propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, heptane, Octane, petroleum ether, halides of methane, tetraalkylsilanes and other low-boiling liquids; azodimethylamides which are vaporized after thermal decomposition, etc.

Examples of the material constituting the above-mentioned shell include nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, and fumaric nitrile; acrylic acid, methacrylic acid, Iconic acid, maleic acid, fumaric acid, citraconic acid and other carboxylic acid monomers; vinylidene chloride; vinyl acetate; methyl (meth)acrylate, ethyl (meth)acrylate, n-Butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, cyclohexyl (meth)acrylate, (meth)acrylate (Meth)acrylates such as benzyl acrylate, β-carboxyethyl acrylate; styrene monomers such as styrene, α-methylstyrene, chlorostyrene; acrylamide, substituted acrylamide, methacrylamide A polymer composed of amide monomers such as amines and substituted methacrylamides. The polymer composed of these monomers may be a homopolymer or a copolymer. Examples of the copolymer include vinylidene chloride-methyl methacrylate-acrylonitrile copolymer, methyl methacrylate-acrylonitrile-methacrylonitrile copolymer, methyl methacrylate-acrylonitrile Copolymer, Acrylonitrile-Methacrylonitrile-Iconic Acid Copolymer, etc.

As the thermally expandable microspheres, an inorganic foaming agent or an organic foaming agent can be used. As an inorganic foaming agent, ammonium carbonate, ammonium hydrogencarbonate, sodium hydrogencarbonate, ammonium nitrite, sodium borohydride, various azides, etc. are mentioned, for example. In addition, as the organic foaming agent, for example, chlorofluoroalkane-based compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azobisisobutyronitrile, azodimethylamide, azobis Azo compounds such as barium formate; p-toluenesulfohydrazine, diphenyl-3,3'-disulfohydrazine, 4,4'-oxybis(benzenesulfohydrazine), allylbis(sulfohydrazine) hydrazine) and other hydrazine compounds; p-toluenesulfonamidourea, 4,4'-oxybis (benzenesulfonamidourea) and other aminourea compounds; 5-morpholino-1,2,3, Triazole compounds such as 4-thitriazole; N,N'-dinitrosopentamethylenetetramine, N,N'-dimethyl-N,N'-dinitrosoterephthalide N-nitroso compounds such as amines, etc.

A commercial item can also be used for the said heat-expandable microsphere. Specific examples of commercially available heat-expandable microspheres include trade name "Matsumoto Microsphere" (grades: F-30, F-30D, F-36D, F-36LV, F- 50, F-50D, F-65, F-65D, FN-100SS, FN-100SSD, FN-180SS, FN-180SSD, F-190D, F-260D, F-2800D), the trade name manufactured by Japan's Fillite company "Expancel" (Grades: 053-40, 031-40, 920-40, 909-80, 930-120), "DAIFOAM" manufactured by Kureha Chemical Industry Co., Ltd. (Grades: H750, H850, H1100, S2320D, S2640D, M330 , M430, M520), "ADVANCELL" manufactured by Sekisui Chemical Industry Co., Ltd. (grades: EML101, EMH204, EHM301, EHM302, EHM303, EM304, EHM401, EM403, EM501), etc.

The particle size of the heat-expandable microspheres before heating is preferably 0.5 μm to 80 μm, more preferably 5 μm to 45 μm, further preferably 10 μm to 20 μm, particularly preferably 10 μm to 15 μm. Therefore, the particle size of the thermally expandable microspheres before heating is preferably 6 μm to 45 μm, more preferably 15 μm to 35 μm, in terms of the average particle diameter. The above-mentioned particle diameter and average particle diameter are values that can be determined by a particle size distribution measurement method in a laser scattering method.

It is preferable that the said heat-expandable microspheres have suitable intensity|strength so that they do not break until the volume expansion rate becomes preferably 5 times or more, more preferably 7 times or more, and still more preferably 10 times or more. In the case of using such heat-expandable microspheres, the adhesive force can be efficiently reduced by heat treatment.

The content ratio of the heat-expandable microspheres in the above-mentioned adhesive layer can be appropriately set according to the desired reduction of the adhesive force and the like. With respect to 100 parts by weight of the base polymer forming the second adhesive layer, the content ratio of the heat-expandable microspheres is, for example, 1 part by weight to 150 parts by weight, preferably 10 parts by weight to 130 parts by weight, and more preferably 25 parts by weight ~100 parts by weight.

When the above-mentioned adhesive layer contains heat-expandable microspheres, the arithmetic surface roughness Ra of the adhesive layer before the expansion of the heat-expandable microspheres (that is, before heating) is preferably 500 nm or less, more preferably 400 nm or less, and further Preferably it is 300 nm or less. Within such a range, an adhesive sheet excellent in adhesion to an adherend can be obtained. Such an adhesive layer with excellent surface smoothness can be obtained, for example, by making the thickness of the adhesive layer within the above range, or by applying another adhesive layer to a release liner and then transferring the adhesive layer. Furthermore, as explained in the above-mentioned item A, when the adhesive sheet of the present invention is further provided with another adhesive layer, the other adhesive layer may include thermally expandable microspheres. In the case where the other adhesive layer includes thermally expandable microspheres, the arithmetic surface roughness Ra of the adhesive layer is also preferably within the above range.

When the above-mentioned adhesive layer contains thermally expandable microspheres, the above-mentioned adhesive layer preferably contains a dynamic storage modulus at 80°C in the range of 5 kPa to 1 MPa (more preferably 10 kPa to 0.8 MPa). Adhesive made from the base polymer. If it is such an adhesive layer, it can form the adhesive sheet which has moderate adhesiveness before heating, and the adhesive force is easily reduced by heating. Furthermore, the dynamic storage modulus can be measured under the measurement conditions of a frequency of 1 Hz and a heating rate of 10° C./min using a dynamic viscoelasticity measuring device (eg, trade name “ARES” manufactured by Rheometrics).

E. Manufacturing method of an adhesive sheet The adhesive sheet of this invention can be manufactured by any suitable method. For example, the adhesive sheet of the present invention can be exemplified by the method of directly coating the composition containing the acrylic adhesive on the substrate, or the method of coating the composition containing the acrylic adhesive on any suitable substrate. The method of transferring the coating layer to the substrate, etc. The composition containing the acrylic adhesive may contain any suitable solvent.

In the case of forming the adhesive layer containing the heat-expandable microspheres, the adhesive layer can be formed by coating a composition containing the heat-expandable microspheres, the adhesive and any suitable solvent on the substrate. Alternatively, the heat-expandable microspheres may be sprinkled on the adhesive coating layer, and the heat-expandable microspheres may be embedded in the adhesive using a laminating machine or the like to form an adhesive layer containing the heat-expandable microspheres.

As a coating method of the above-mentioned adhesive agent and each composition, any suitable coating method can be adopted. For example, each layer can be formed by drying after coating. As a coating method, the coating method using a multi-coater (Multi Coater), a die coater, a gravure coater, an applicator, etc. is mentioned, for example. As a drying method, natural drying, heat drying, etc. are mentioned, for example. In the case of heating and drying, the heating temperature can be set to any suitable temperature according to the properties of the material to be dried. [Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention should not be limited to the examples. The evaluation methods in the examples are as follows. In addition, in the Example, unless otherwise specified, "part" and "%" are based on weight.

(1) T ₂ relaxation time (T _2s ) of the S component of the adhesive layer obtained by pulse NMR Using Bruker's trade name "TD-NMR the minispecmq20", 100 mg of the adhesive layer was taken as a measurement sample, and the The T ₂ relaxation curve was obtained by measurement by the solid-state echo method, and the T ₂ relaxation curve was substituted into the following formula (1) to obtain the T ₂ relaxation time (T _2s ) of the S component of the adhesive layer obtained by pulse NMR. . M(t)=α・exp(-(1/Wa)(t/T _2s ) ^Wa ) +β・exp(-(1/Wa)(t/T _2L ) ^Wa )・・・(1) M(t ): Free induced decay α: Proton ratio (%) of the component with a shorter relaxation time (S component) T _2s : T ₂ relaxation time of the S component (msec) β: Component with a longer relaxation time (L component) ) proton ratio (%) T _2L : T ₂ relaxation time of the L component (msec) t: Observation time (msec) Wa: shape factor (=1) The measurement conditions in the above measurement are as follows.・90° pulse width: 2.1 μsec ・Repeat time: 1 sec ・Accumulation times: 32 ・Measurement temperature: 30℃ manufacturing), under the conditions of probe: needle penetration, nitrogen flow rate: 50.0 ml/min, press load: 0.01 N, measurement ambient temperature: 23.0°C, press load time: 60 min, the first adhesive layer was measured. sink amount. When N=5, five measurements are performed, the maximum value and the minimum value among the measured values are excluded, and the average value of N=3 is taken as the sinking amount of the sample. (3) Thickness change caused by dropwise addition of 4-tert-butylphenyl glycidyl ether A specific amount of 4-tert-butylphenyl (0.02 g using a syringe with a diameter of 22 mm) was added dropwise to the surface of the adhesive layer. Glycidyl ether was placed in an environment of 23°C and 50% RH for 1 minute. After 4-tert-butylphenyl glycidyl ether was wiped off, the thickness (Dt) at the dropwise position was determined from the thickness before the dropwise addition operation. For the thickness (It) at this position, the thickness change rate ((Dt−It)/It) and the thickness change amount (Dt−It) were obtained. (4) Adhesion (for PET) Using a 2 kg hand roller, the entire surface of the adhesive sheet (width 20 mm × length 140 mm) on the opposite side of the adhesive layer is covered with double-sided tape (manufactured by Nitto Denko Co., Ltd., Brand name "No.531") SUS304 board is attached. Next, a polyethylene terephthalate film (manufactured by Toray Co., Ltd., trade name "" Lumirror S-10”, thickness: 25 μm, width: 30 mm). The sample for evaluation obtained in the above manner was used for the tensile test. As a tensile tester, a trade name "Shimadzu Autograph AG-120kN" manufactured by Shimadzu Corporation was used. The tensile test was started after the sample for evaluation was installed in the tensile tester and left to stand at an ambient temperature of 23° C. for 30 minutes. The conditions of the tensile test were set as peeling angle: 180°, peeling speed (tensile speed): 300 mm/min. The load at the time of peeling the adhesive sheet from the PET film was measured, and the maximum load at that time was taken as the adhesive force of the adhesive sheet. (5) Adhesion (for sealing resin) Attach a mold frame (mold size: 35 mm x 90 mm rectangle, thickness: 564 μm) on the first adhesive layer of the adhesive sheet (width 50 mm × length 140 mm). ), sprinkle a granular epoxy resin-based sealant (manufactured by Sumitomo Bakelite Co., Ltd., G730) in the mold frame with a thickness of 0.3 mm after hardening, and then cover it with a silicone-treated release liner. "Hydraulic Press Forming Machine NS-VPF-50" manufactured by Meisho Press, at a temperature of 145°C, a forming time of 600 seconds, a pressure condition of 0.3 MPa (stage size of 300 mm□), a vacuum time of 600 seconds, and a degree of vacuum - Under the condition of 0.1 MPa, the sealing resin is heated and formed on the adhesive layer. Then, the sealing resin was cured in an oven under a heating environment of 150° C.×7 hours. After the sealing resin was cured, the sample was allowed to stand at 23°C and 50% RH for 2 hours, and the part of the sealing resin in contact with the first adhesive layer was cut into a size of 20 mm in width and 88 mm in length. The sample for evaluation obtained in the above manner was used for the tensile test. As a tensile tester, a trade name "Shimadzu Autograph AG-120kN" manufactured by Shimadzu Corporation was used. The tensile test was started after the sample for evaluation was installed in the tensile tester and left to stand at an ambient temperature of 23° C. for 30 minutes. The conditions of the tensile test were set as peeling angle: 180°, peeling speed (tensile speed): 300 mm/min. The load at the time of peeling the adhesive sheet from the sealing resin was measured, and the average load at that time was taken as the adhesive force of the adhesive sheet. (6) The level difference between the semiconductor chip and the sealing resin Under the conditions described below, the sealing step is performed on the surface of the adhesive of the adhesive tape, and the level difference between the semiconductor wafer (Si wafer) and the sealing resin is measured. amount (standoff)). Carrier: SUS carrier 220 mmϕ Wafer: Si mirror wafer 7 mm × 7 mm × 400 μm thickness Bonding device: FC3000W (manufactured by Toray Engineering) Bonding conditions: as follows N Crimping temperature: 23°C Sealing equipment: MS-150HP (manufactured by APIC YAMADA CORPORATION) Sealing resin: G730 (manufactured by Sumitomo Bakelite) Preheating conditions: 130°C x 30 seconds Preheating time before starting sealing: 1 hour for sealing Temperature: 145° C. Vacuum time: 5 seconds Sealing time: 600 seconds Clamping force: 3.6 MPa Sealing thickness: 600 μm The sealing operation was carried out according to the following procedure. 1) Attach the adhesive sheet to the SUS carrier. Attachment conditions: Attachment roller pressure at 23°C: 0.1 MPa Attachment speed: 0.5 m/min The SUS attachment surface is the outside of the second adhesive layer. When the adhesive sheet is a single-sided tape (without the second adhesive layer), use a silicone release liner (MRF38, manufactured by Mitsubishi Chemical) with a PET film thickness of 38 μm and a silicone release with a PET film thickness of 75 μm A liner (PET-75-SCA0, manufactured by FUJICO) was used to form an adhesive layer (48 μm) containing thermally expandable microspheres without a base material, and the SUS carrier and the single-sided tape were fixed by the adhesive layer, and the evaluation was carried out. 2) On the adhesive layer of the adhesive sheet attached to the SUS carrier, one Si mirror wafer was placed using a bonding apparatus. 3) Preheating for a specific time is performed on the SUS carrier in the state where the Si mirror wafer is attached. 4) After preheating, let it stand for 1 hour at 23°C and 50%RH, and then use specific sealing equipment and resin to carry out sealing under specific conditions. The SUS carrier is sprinkled with sealing resin, and the sealing operation is carried out. 5) The layered product obtained by the sealing operation is heated and hardened at 150°C for 4 hours using an oven. 6) After placing the heat-hardened laminate at 23°C and 50% RH for 5 days, heat the laminate on a hot plate to foam and peel the adhesive attached to the SUS carrier, and separate the SUS carrier. Tool. 7) The adhesive tape was peeled off from the laminated body separated from the SUS carrier to obtain a sealing body of the sealing resin and the Si wafer. 8) Using a laser confocal microscope (manufactured by OLS-4000 OLYMPUS), measure the level difference of the interface between the Si wafer and the sealing resin on the surface of the sealing body between the sealing resin and the Si wafer and the surface in contact with the adhesive, and measure the sealing resin and Si The step height of the interface of the chip.

[Example 1] 100 parts by weight of acrylic copolymer A (copolymer of 2-ethylhexyl acrylate and acrylic acid, 2-ethylhexyl acrylate structural unit: acrylic structural unit=95:5 (weight ratio)), epoxy-based cross-linked 5 parts by weight of a joint agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C") and 100 parts by weight of toluene were mixed to prepare a composition for forming an adhesive layer. The composition for forming an adhesive layer was coated on one surface of a polyethylene terephthalate film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 38 μm) as a substrate to obtain a substrate and a first An adhesive sheet (1) composed of an adhesive layer (thickness 10 μm). Acrylic copolymer C (copolymer of 2-ethylhexyl acrylate, ethyl acrylate, methyl methacrylate and 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate structural unit: ethyl acrylate structural unit : Methyl methacrylate Structural unit: Acrylic structural unit = 30:70:5:4 (weight ratio)) 100 parts by weight, thermally expandable microspheres (manufactured by Matsumoto Oil Pharmaceutical Co., Ltd., trade name "Matsumoto Microsphere F-190D") 30 parts by weight, 1.4 parts by weight of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L"), 10 parts by weight of an adhesion imparting agent (manufactured by YASUHARA Chemicals, trade name "Mighty Ace G125"), and 100 parts by weight of toluene The composition for forming an adhesive layer is prepared by mixing 100 parts, and the adhesive layer is coated on the opposite side of the polyethylene terephthalate film of the adhesive sheet (1) to the first adhesive layer to form a composition. Using the composition, a second adhesive layer (thickness: 45 μm) was formed to obtain a double-sided adhesive sheet.

[Example 2] 100 parts by weight of acrylic copolymer A (copolymer of 2-ethylhexyl acrylate and acrylic acid, 2-ethylhexyl acrylate structural unit: acrylic structural unit=95:5 (weight ratio)), epoxy-based cross-linked 5 parts by weight of a joint agent (manufactured by Mitsubishi Gas Chemicals, trade name "Tetrad C"), 10 parts by weight of an adhesion imparting agent (manufactured by YASUHARA Chemicals, trade name "Mighty Ace G125"), and 100 parts by weight of toluene were mixed to prepare A composition for forming an adhesive layer. The composition for forming an adhesive layer was coated on one surface of a polyethylene terephthalate film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 38 μm) as a substrate to obtain a substrate and a first An adhesive sheet (2) composed of an adhesive layer (thickness 10 μm). In the same manner as in Example 1, a second adhesive layer was formed on the opposite side of the polyethylene terephthalate film of the adhesive sheet (2) to the first adhesive layer to obtain a double-sided adhesive Sheet.

[Example 3] The acrylic copolymer B (copolymer of ethyl acrylate, butyl acrylate, acrylic acid and 2-hydroxyethyl acrylate, ethyl acrylate structural unit: butyl acrylate structural unit: acrylic acid: 2-hydroxyethyl acrylate structural unit structure Unit = 50:50:5:0.1 (weight ratio)) 100 parts by weight, epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemicals, trade name "Tetrad C") 5 parts by weight, adhesion imparting agent (manufactured by YASUHARA Chemicals) , trade name "Mighty Ace G125") 10 parts by weight and 100 parts by weight of toluene were mixed to prepare a composition for forming an adhesive layer. The composition for forming an adhesive layer was coated on one surface of a polyethylene terephthalate film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 38 μm) as a substrate to obtain a substrate and a first An adhesive sheet (3) composed of an adhesive layer (thickness 10 μm). In the same manner as in Example 1, a second adhesive layer was formed on the opposite side of the polyethylene terephthalate film of the adhesive sheet (3) to the first adhesive layer to obtain a double-sided adhesive Sheet.

[Example 4] A double-sided adhesive sheet was obtained in the same manner as in Example 2, except that a polyethylene terephthalate film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 100 μm) was used as a base material.

[Comparative Example 1] Acrylic copolymer C (copolymer of 2-ethylhexyl acrylate, ethyl acrylate, methyl methacrylate and 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate structural unit: ethyl acrylate structural unit : methyl methacrylate structural unit: 2-hydroxyethyl acrylate structural unit = 30:70:5:4 (weight ratio)) 100 parts by weight, isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L" ) 1.5 parts by weight, 5 parts by weight of an adhesion imparting agent (manufactured by YASUHARA Chemicals, trade name "Mighty Ace G125"), and 100 parts by weight of toluene were mixed to prepare a composition for forming an adhesive layer. The composition for forming an adhesive layer was coated on one surface of a polyethylene terephthalate film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 38 μm) as a substrate to obtain a substrate and an adhesive. Adhesive sheet (4) composed of layers (thickness 10 μm). In the same manner as in Example 1, a second adhesive layer was formed on the opposite side of the polyethylene terephthalate film of the adhesive sheet (4) to the first adhesive layer to obtain a double-sided adhesive Sheet.

[Comparative Example 2] Acrylic copolymer D (copolymer of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate structural unit: 2-hydroxyethyl acrylate structural unit=100:4 (weight ratio) )) 100 parts by weight, 1.5 parts by weight of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L"), and 100 parts by weight of toluene were mixed to prepare a composition for forming an adhesive layer. The composition for forming an adhesive layer was coated on one surface of a polyethylene terephthalate film (manufactured by Toray Corporation, trade name "Lumirror S10", thickness 38 μm) as a substrate to obtain a substrate and an adhesive. Adhesive sheet (5) composed of layers (thickness 10 μm). In the same manner as in Example 1, a second adhesive layer was formed on the opposite side of the polyethylene terephthalate film of the adhesive sheet (5) to the first adhesive layer to obtain a double-sided adhesive Sheet.

[Table 1] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Amount (parts by weight) of ingredients of the adhesive composition for forming a first adhesive layer prepolymer Polymer A (2EHA/AA=95/5) 100 100 100 Polymer B (EA/BA/AA/HEA=50/50/5/0.1) 100 Polymer C (2EHA/EA/MMA/HEA=30/70/5/4) 100 Polymer D (2EHA/HEA=100/4) 100 cross-linking agent Coronate L (Isocyanate Crosslinker) 1.5 1.5 Tetrad C (epoxy crosslinker) 5 5 5 5 adhesion imparting agent 10 10 10 5 Adhesive Thickness [μm] 10 10 10 10 10 10 Substrate thickness [μm] 38 38 38 100 38 38 Evaluation Thickness of the adhesive before 4-tert-butylphenyl glycidyl ether dropwise addition [μm] 10 10 10 10 10 10 Thickness of adhesive after dropwise addition of 4-tert-butylphenyl glycidyl ether [μm] 16 16 18 16 11 33 Variation of adhesive thickness [μm] 5 6 8 6 1 twenty three Rate of change in adhesive thickness 60% 60% 80% 60% 10% 230% Pulse NMR (S component) T2 [μsec] 28 28 25 28 52 61 Sp value of base polymer [(J/cm ³ )^ ^1/2 ] 19.3 19.3 19.6 19.3 20.7 19.1 Adhesion to resin [N/20 mm] 0.6 1.1 10 0.5 19 2.4 Adhesion to PET [N/20 mm] 0.12 0.23 0.52 0.23 4.73 4.6 TMA sinking amount [μm] 23℃ environment 1.8 2 1.1 2 3.1 4 TMA sinking amount [μm] 145℃ environment 34 34 34 15 33 35 Sealing resin/Si wafer interface step height [μm] 2.4 2.6 1.9 2.6 3.6 3.1

1: Semiconductor wafer 2: Sealing resin 2': A composition comprising a monomer as a precursor of a sealing resin 10: Substrate 20: Adhesive layer 30: Second adhesive layer 100,100',200: Adhesive sheet A: Structure including semiconductor chip and sealing resin

FIG. 1 is a schematic cross-sectional view of an adhesive sheet according to an embodiment of the present invention. FIG. 2( a ) is a diagram for explaining an example of the case where the previous adhesive sheet is used in the resin sealing step of the semiconductor wafer. (b) is a figure explaining an example of the case where the adhesive sheet of this invention is used in the resin sealing process of a semiconductor wafer. 3 is a schematic cross-sectional view of an adhesive sheet according to another embodiment of the present invention.

10: Substrate

20: Adhesive layer

100: Adhesive sheet

Claims (14)

An adhesive sheet, which is provided with a base material and an adhesive layer disposed on at least one side of the base material, the adhesive layer contains an acrylic adhesive, and the adhesive sheet is prepared by using TMA to precipitate in an environment of 23° C. The input amount is 5 μm or less, and the T ₂ relaxation time (T _2s ) of the S component of the adhesive layer obtained by pulse NMR is 45 μsec or less. The adhesive sheet of claim 1, wherein 4-tert-butylphenyl glycidyl ether is dropped on the surface of the adhesive layer, and the thickness change rate of the adhesive layer is less than 160% after standing for 1 minute. The adhesive sheet of claim 1 or 2, wherein 4-tert-butylphenyl glycidyl ether is added dropwise to the surface of the adhesive layer, and the thickness change of the adhesive layer after standing for 1 minute is 20 μm or less. The adhesive sheet according to any one of claims 1 to 3, wherein the adhesive layer contains an adhesive, and the adhesive contains an sp value of 18 (cal/cm ³ ) ^1/2 to 20 (cal/cm ³ ) ^{1 /2} of the base polymer. The adhesive sheet according to any one of claims 1 to 4, wherein the above-mentioned acrylic adhesive comprises a cross-linked body of an acrylic polymer as a base polymer. The adhesive sheet according to any one of claims 1 to 5, wherein the above-mentioned acrylic adhesive comprises an epoxy-based crosslinking agent. The adhesive sheet according to claim 6, wherein the blending amount of the epoxy-based crosslinking agent is 0.6 parts by weight to 15 parts by weight relative to 100 parts by weight of the acrylic polymer. The adhesive sheet according to any one of claims 1 to 7, wherein the base material is a resin sheet composed of a resin having a glass transition temperature (Tg) of 25°C or higher. The adhesive sheet according to any one of claims 1 to 8, wherein the thickness of the substrate is 20% to 90% relative to the total thickness of the adhesive sheet. The adhesive sheet according to any one of claims 1 to 9, wherein the amount of sinking in the 145° C. environment obtained by using TMA of the above-mentioned adhesive sheet is 1 μm˜35 μm. The adhesive sheet according to any one of claims 1 to 10, wherein the amount of nitrogen gas generated when the adhesive layer is heat-treated is 0.06% by weight to 1.0% by weight. The adhesive sheet according to any one of claims 1 to 11, comprising: the above-mentioned base material, the above-mentioned adhesive layer arranged on one side of the base material, and a side opposite to the adhesive layer arranged on the base material The second adhesive layer on the side. The adhesive sheet according to any one of claims 1 to 12, which is a temporary fixing material usable in a resin sealing step of a semiconductor wafer. The adhesive sheet according to claim 13 is used for curing the sealing resin on the above-mentioned adhesive sheet.

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