TWI687500B - Adhesive sheet - Google Patents

Abstract

The present invention provides an adhesive sheet having a rigid substrate with a Young's modulus of 1000 MPa or more, a buffer layer provided on one side of the rigid substrate, and an adhesive provided on the other side of the rigid substrate The adhesive sheet of the adhesive layer is characterized in that the buffer layer is a layer formed from a composition for forming a buffer layer containing an energy ray polymerizable compound, and has a triangular hammer-shaped indenter with a radius of curvature of 100 nm and an angle of 115° between edges At the tip of 10μm/min, the squeezing depth (X) necessary to reach 2mN when the compression load when squeezed into the buffer layer is 2.5μm or more, is an adhesive sheet, excellent in foreign body adsorption, as a semiconductor wafer Grinding of processed BG sheets can prevent cracking of semiconductor wafers.

Description

Adhesive sheet

The present invention relates to an adhesive sheet. More specifically, for example This is an adhesive sheet that prevents the semiconductor wafer from cracking when used as a back-grinding sheet for semiconductor wafer grinding.

The thinning, miniaturization, and multi-functionalization of information terminal devices are progressing rapidly, and the semiconductor wafers equipped with these are also the same, and are seeking thinning and high density. In the past, it was necessary to produce semiconductor wafers with a thickness of about 350 μm to a thickness of 50 to 100 μm or less. In order to meet the requirements for thinning of such semiconductor wafers, the inner surface of the semiconductor wafer is being ground for thinning.

In recent years, bumps (electrodes) composed of solders with a height of about 30 μm to 100 μm are sometimes formed on the surface, and the inner surface of a semiconductor wafer having irregularities is ground. When grinding the semiconductor wafer with such bumps on the inner surface, in order to protect the surface of the bump portion, a dedicated adhesive sheet (back ground grinding sheet (BG sheet)) is attached to the surface where the bump portion is formed.

For example, in Patent Document 1, it is disclosed that after forming a groove of a specific depth from the surface side of the wafer, the first cutting is performed from the inner side of the wafer. In the dicing method, the adhesive sheet used to protect the surface side of the wafer. The adhesive sheet disclosed in Patent Document 1 has a configuration in which a vibration relaxation layer is provided on the surface on one side of the rigid substrate and an adhesive layer is provided on the surface on the other side.

The adhesive sheet disclosed in this Patent Document 1 adjusts the thickness of the rigid substrate and Young's modulus, and the thickness of the vibration alleviation layer and the maximum value of the dynamic viscoelastic tan δ to a specific range, and the first cutting method is used as BG When the sheet is used, it can manufacture extremely thin semiconductor wafers without cracks or discoloration.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2005-343997

However, when cutting the inner surface of the semiconductor wafer, when the BG sheet of the semiconductor wafer to which the BG sheet is attached is placed on the chuck base of the wafer inner surface cutting machine, the BG sheet is attached to the chuck base The foreign matter is the cause. Due to the cutting process of the semiconductor wafer, the semiconductor wafer may be cracked.

That is, when a BG sheet of a semiconductor wafer with a BG sheet is provided on a chuck base to which a foreign substance is attached, the BG sheet is only the thickness of the foreign substance, and the opposite side of the foreign substance swells to form a convex portion on the inner surface of the semiconductor wafer . In this state, when the inner surface of the semiconductor wafer is cut, the vicinity of the protruding portion formed on the inner surface of the semiconductor wafer is thinner than other parts, and is prone to cracking.

Still, in Patent Document 1, there is no research on wafer cracking caused by such foreign objects on the chuck base.

Therefore, the adhesive sheet used in such a semiconductor wafer cutting process seeks to suppress the degree of swelling of the foreign substance on the opposite side of the foreign substance even if the adhesive sheet is provided on the seat where the foreign substance is attached.

The present invention is intended to provide an adhesive sheet that is excellent in adsorption of foreign substances and, for example, is used as a BG sheet for grinding and processing semiconductor wafers to prevent cracking of the semiconductor wafer.

The inventors found that a rigid substrate with a Young's modulus above a certain value has a buffer layer on one side and an adhesive layer on the other side. The buffer layer squeezes a specific shape of indenter into the buffer layer When the compressive load at the time reaches 2mN, the adhesive sheet with a squeezing depth of more than a certain value can solve the above-mentioned problems and complete the present invention.

That is, the present invention provides the following [1] to [9].

[1] An adhesive sheet comprising a rigid substrate having a Young's modulus of 1000 MPa or more, a buffer layer provided on one side of the rigid substrate, and an adhesive provided on the other side of the rigid substrate The adhesive sheet of the layer is characterized in that the aforementioned buffer layer is a layer formed of a composition for forming a buffer layer containing an energy ray polymerizable compound, and a triangular hammer-shaped indenter having a apex curvature radius of 100 nm and an inter-angle of 115° At the speed of 10μm/min, the squeezing depth (X) necessary for the compression load to reach 2mN when squeezed into the buffer layer is 2.5μm or more.

[2] The adhesive sheet according to [1] above, wherein the composition for forming a buffer layer as the energy ray polymerizable compound contains ethyl urethane (meth)acrylate (a1) and has a ring-forming atom Number 6 to 20 of the alicyclic group or heterocyclic group polymerizable compound (a2), and the functional group of the polymerizable compound (a3).

[3] The adhesive sheet according to [2] above, wherein the content ratio of the component (a2) to the component (a3) in the buffer layer forming composition [(a2)/(a3)] is 0.5 to 3.0.

[4] The adhesive sheet as described in [2] or [3] above, wherein the component (a2) is an alicyclic group-containing (meth)acrylate.

[5] The adhesive sheet according to any one of [2] to [4] above, wherein the component (a3) is a hydroxyl group-containing (meth)acrylate.

[6] The adhesive sheet according to any one of [1] to [5] above, wherein the thickness of the buffer layer is 5 to 100 μm.

[7] The adhesive sheet according to any one of [1] to [6] above, wherein the maximum value of the tan δ of the dynamic viscoelasticity at -5 to 120° C. of the buffer layer is 0.5 or more.

[8] The adhesive sheet according to any one of [1] to [7] above, wherein at least one of the rigid substrate and the buffer layer and the rigid substrate and the adhesive layer With easy adhesion layer.

[9] The adhesive sheet according to any one of the above [1] to [8], which is used for cutting a semiconductor wafer and is used as a back grinding sheet for protecting the surface side of the semiconductor wafer.

The adhesive sheet of the present invention is excellent in foreign substance adsorption. Therefore, when the adhesive sheet of the present invention is used as a BG sheet for grinding a semiconductor wafer, for example, it can prevent cracking of the semiconductor wafer.

1a, 1b, 1c, 1d

11‧‧‧Rigid substrate

12‧‧‧buffer layer

13‧‧‧Adhesive layer

14a, 14b ‧‧‧ peel sheet

15a, 15b‧‧‧easy adhesion layer

1 is a cross-sectional view of an adhesive sheet showing an example of the configuration of the adhesive sheet of the present invention.

In the description of this specification, the "energy rays" refer to ultraviolet rays, electron beams, etc., and preferably ultraviolet rays or electron beams.

In addition, in the description of this specification, "mass average molecular weight (Mw)" refers to the value converted to standard polystyrene measured by gel permeation chromatography (GPC) method, specifically, according to the method described in the examples The measured value.

In addition, in the description of this specification, for example, "(meth)acrylate" means both "acrylate" and "methacrylate", and other similar terms are also the same.

[Composition of Adhesive Sheet]

The adhesive sheet of the present invention is not particularly limited as long as it has a rigid substrate, a buffer layer provided on one side of the rigid substrate, and an adhesive layer provided on the other side of the rigid substrate.

1 is a cross-sectional view of an adhesive sheet showing an example of the configuration of the adhesive sheet of the present invention.

As an example of the configuration of the adhesive sheet of the present invention, as shown in FIG. 1( a ), it can be cited that the rigid substrate 11 has a buffer layer 12 on the surface side, and the rigid substrate 11 has an adhesive layer on the other surface side. The adhesive sheet 1a of the adhesive layer 13.

Moreover, the adhesive sheet of the present invention is adhered as shown in FIG. 1(a) The sheet 1a can serve as an adhesive sheet on which at least one side of the buffer layer 12 and the adhesive layer 13 further has a peeling sheet.

Although the adhesive sheet 1b shown in FIG. 1(b) is provided on both sides of the buffer layer 12 and the adhesive layer 13 with peeling sheets 14a and 14b, respectively, the adhesive sheet of the present invention may be only on the buffer layer 12 and one side of the adhesive layer 13 are provided with a release sheet.

In addition, the adhesive sheet of the present invention is shown in FIGS. 1(a) and (b) The adhesive sheets 1a and 1b can be used as at least one side between the rigid substrate 11 and the buffer layer 12 and between the rigid substrate 11 and the adhesive layer 13 and have an easy-adhesive layer.

The configuration of the adhesive sheets 1c, 1d shown in FIGS. 1(c) and (d) with respect to the above-mentioned adhesive sheets 1a, 1b is further between the rigid substrate 11 and the buffer layer 12, and between the rigid substrate 11 and the adhesive layer Between 13, there is a configuration in which easy-adhesion layers 15a and 15b are provided. Still, the adhesive sheet of the present invention may be configured to provide only the side of the easy-adhesion layers 15a and 15b.

In addition, although the adhesive sheet 1d shown in FIG. 1(d) has the peeling sheets 14a and 14b provided on both surfaces of the buffer layer 12 and the adhesive layer 13, respectively Structure, but the adhesive sheet of the present invention may be configured to provide a release sheet only on one side of the buffer layer 12 and the adhesive layer 13.

Hereinafter, each layer constituting the adhesive sheet of the present invention will be described in detail.

<rigid substrate>

The rigid substrate of the adhesive sheet of the present invention is a rigid substrate with a Young's modulus of 1000 MPa or more. When using a substrate with a Young's modulus of less than 1000 MPa, when the resulting adhesive sheet is attached to a semiconductor wafer, due to the greater extension of the substrate, stress is likely to occur because the semiconductor after the adhesive sheet is attached is likely to occur Wafer warpage is therefore poor.

In addition, in the adhesive sheet of the present invention, even when a semiconductor substrate is attached by using a rigid substrate having a Young's modulus of 1000 MPa or more, the substrate can be suppressed from being warped due to the small extension of the substrate. For example, even on the surface of a semiconductor wafer, a structure such as warpage provided with an organic film is likely to occur. Since the entire adhesive sheet has rigidity, the warpage of the semiconductor wafer can be suppressed.

Young's mold as a rigid substrate used in the present invention Amount, from the viewpoint of suppressing warpage of the semiconductor wafer when attaching the obtained adhesive sheet to the semiconductor wafer, and from the viewpoint of improving workability (mechanical suitability) when attaching the adhesive sheet to the semiconductor wafer In view of this, it is preferably 1,000 to 30,000 MPa, more preferably 1,300 to 20,000 MPa, even more preferably 1,600 to 15,000 MPa, and still more preferably 1,800 to 10,000 MPa.

Still, the Young's modulus of the rigid substrate of the present invention means the value measured by the method described in the examples.

The thickness of the rigid substrate if the Young's modulus of the rigid substrate is above Although the scope is not particularly limited, from the viewpoint of improving the workability (mechanical suitability) when attaching the adhesive sheet of the present invention to a semiconductor wafer, and reducing the peeling of the adhesive sheet from the semiconductor wafer (wafer) From the viewpoint of stress, it is preferably 10 to 1000 μm, more preferably 20 to 400 μm, still more preferably 25 to 150 μm, and still more preferably 30 to 120 μm.

As the rigid substrate used in the present invention, if the Young's modulus Although the above range is not particularly limited, it is preferably a resin film from the viewpoint of water resistance and heat resistance.

Examples of the resin constituting the resin film include polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and fully aromatic polyesters, and polyamides. , Polyimide, Polyacetal, Polycarbonate, Modified Polyphenylene Ether, Polysulfide Benzene, Polysulfone, Polyether Ketone, Biaxially Drawn Polypropylene, etc.

Among these resins, one or more selected from the group consisting of polyester, polyamide, polyimide, and biaxially drawn polypropylene are preferred, more preferably polyester, and even more preferably polyterephthalic acid Ethylene glycol.

Still, the rigid substrate used in the present invention may be a single-layer film selected from a resin film composed of one or more of the above resins, or may be a laminate of two or more of these resin films Laminated film.

In addition, the rigid substrate used in the present invention Within the scope of the effects of the invention, fillers, colorants, antistatic agents, antioxidants, organic lubricants, catalysts, etc. may also be included.

In addition, the substrate can be transparent or opaque, and can be Coloring or evaporation.

In addition, in order to improve the adhesion to the buffer layer and/or the adhesive layer on the surface of at least one side of the rigid substrate used in the present invention, a subsequent treatment such as corona treatment may be performed, and the following may be provided. Easy to layer.

<buffer layer>

The buffer layer of the adhesive sheet of the present invention is a layer formed of a composition for forming a buffer layer containing an energy ray polymerizable compound, and a triangular hammer-shaped indenter with a tip radius of curvature of 100 nm and an inter-angle of 115° Adjust the squeezing depth (X) necessary for the compression load when the compressive load reaches 2mN when squeezing into the buffer layer at a speed of 10μm/minute (hereinafter also referred to as "squeezing depth (X)") to a layer of 2.5μm or more .

Since the buffer layer is formed of a composition for forming a buffer layer containing an energy ray polymerizable compound, it is relatively easy to adjust the viscoelasticity by selecting the composition of the composition for forming a buffer layer. Therefore, when the adhesive sheet is used as a BG sheet, for example, the vibration caused by grinding of the semiconductor wafer cannot be alleviated, and the occurrence of problems such as cracks or cracks in the semiconductor wafer or floating of the adhesive sheet from the vacuum seat can be suppressed.

In addition, the inventors found that in the structure of the adhesive sheet, by providing a buffer layer that adjusts the above-mentioned squeezing depth (X) to 2.5 μm or more, the foreign substance adsorption is improved, for example, the adhesive sheet of the present invention is used as a semiconductor crystal When using the round ground BG sheet, it can effectively prevent the semiconductor wafer from cracking.

In addition, the adhesive layer having the buffer layer with a penetration depth (X) of less than 2.5 μm When the wafer is stuck, the foreign substance adsorption cannot be sufficiently improved. When this adhesive sheet is used as a BG sheet for semiconductor wafer grinding, there is a tendency for the semiconductor wafer to crack.

The above-mentioned squeeze into the depth (X), the adhesive sheet obtained from lifting From the viewpoint of foreign substance adsorption, it is preferably 2.5 to 20.0 μm, more preferably 2.8 to 15.0 μm, even more preferably 3.0 to 10.0 μm, and still more preferably 3.2 to 7.0 μm.

In the present invention, the penetration depth (X) means the value measured by the method described in the examples.

In addition, the penetration depth (X) can be adjusted within the above-mentioned range by appropriately changing the type or content of the components included in the buffer layer forming composition for forming the buffer layer, the degree of hardening of the buffer layer, and the like.

The maximum viscoelastic tanδ of the buffer layer at -5~120℃ A large value (hereinafter also referred to simply as "the maximum value of tan δ") is preferably 0.5 or more, more preferably 0.8 or more, even more preferably 1.0 or more, and still more preferably 1.2 or more.

If the maximum value of tan δ of the buffer layer is 0.5 or more, in the first dicing method, the obtained adhesive sheet is attached to the wafer group, and when the inner surface of the wafer group is ground, the buffer layer absorbs the vibration of the abrasive particles or The impact effect is higher. Even if the wafer group is ground to 100 μm or less, corner cracking and discoloration of the ground surface can be suppressed.

Still, tan δ is called the loss tangent, and is defined as "loss elastic modulus/storage elastic modulus", which is determined by the dynamic viscoelasticity measuring device by the response to stress such as tensile stress or torsional stress given to the object Measured The value, specifically, means the value measured by the method described in the examples.

In addition, the maximum value of tan δ of this buffer layer does not depend on the above-mentioned penetration depth (X).

The buffer layer of the adhesive sheet of the present invention is composed of The buffer layer containing the energy ray polymerizable compound is formed by the composition.

The energy ray polymerizable compound included in the composition for forming a buffer layer is not particularly limited as long as it can form a buffer layer having an extrusion depth (X) within the above range, for example, photocurable Resin or monomer, etc.

However, from the viewpoint of adjusting the squeeze depth (X) to the above range, as the energy ray polymerizable compound, it is preferable to include ethyl urethane (meth)acrylate (a1) and have a ring formation A composition for forming a buffer layer of a polymerizable compound (a2) of an alicyclic group or a heterocyclic group having 6 to 20 atoms, and a polymerizable compound (a3) having a functional group.

In addition, the composition for forming a buffer layer preferably contains a photopolymerization initiator, and may contain other additives or resin components within a range that does not impair the effects of the present invention.

Hereinafter, each component included in the buffer layer forming composition will be described.

(Ethyl urethane (meth)acrylate (a1))

Ethyl urethane (meth)acrylate used as the present invention (a1) is a compound having at least a (meth)acryloyl group and an urethane bond, and has a property of being polymerized and hardened by energy ray irradiation.

The urethane (meth)acrylate (a1) may be any of an oligomer, a high molecular weight body, or a mixture of these, but it is preferably an urethane (meth)acrylate oligomer Polymer.

The mass average molecular weight (Mw) of the component (a1) is preferably 1,000 ~100,000, better 2,000~60,000, even better 3,000~20,000.

In addition, as the number of (meth)acryloyl groups (hereinafter also referred to as "number of functional groups") in the component (a1), although it may be monofunctional, bifunctional, or more than 3 functional, it is preferably monofunctional or 2 Functional.

The component (a1) can be used, for example, to make the polyol compound different from polyvalent The terminal isocyanate urethane prepolymer obtained by the reaction of the cyanate compound is obtained by reacting (meth)acrylate having a hydroxyl group.

Still, the component (a1) can be used alone or in combination of two or more.

The polyol compound that becomes the raw material of the component (a1) is not particularly limited if it is a compound having two or more hydroxyl groups.

Examples of specific polyol compounds include alkylene glycols, polyether polyols, polyester polyols, and polycarbonate polyols.

Among these, polyester polyols are preferred.

Still, as the polyol compound, although it may be any of a difunctional diol, a trifunctional triol, and a polyhydric alcohol of more than four functionalities, it is preferably a difunctional diol, and more preferably a polyester type two alcohol.

Examples of polyvalent isocyanate compounds include Siya Aliphatic polyisocyanates such as methyl diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate; isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4, 4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, ω,ω'-diisocyanate dimethylcyclohexane and other alicyclic diisocyanates; 4,4'-diphenyl Aromatics such as methane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, naphthalene-1,5-diisocyanate Department of diisocyanates and so on.

Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferred.

For the above-mentioned polyol compound, and polyvalent isocyanate The terminal isocyanate urethane prepolymer obtained by the reaction of the compound is reacted with a (meth)acrylate having a hydroxyl group to obtain urethane (meth)acrylate (a1).

As the (meth)acrylate having a hydroxyl group, if it is a compound having a hydroxyl group and a (meth)acryloyl group in at least one molecule, it is not particularly limited.

As the (meth)acrylate having a specific hydroxyl group, for example, List 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5 -Hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene glycol mono(meth)acrylate , Hydroxyalkyl (meth)acrylates such as polypropylene glycol mono(meth)acrylate; N-hydroxymethyl (meth)acrylamide and other containing hydroxyl groups (Meth) acrylamide; reactants obtained by reacting diglycidyl ester of vinyl alcohol, vinyl phenol, bisphenol A with (meth) acrylic acid, etc.

Among these, hydroxyalkyl (meth)acrylate is preferable, and 2-hydroxyethyl (meth)acrylate is more preferable.

As a terminal isocyanate urethane prepolymer and The conditions for the reaction of (meth)acrylic acid esters with hydroxyl groups are preferably such that the reaction is carried out at 60 to 100°C for 1 to 4 hours in the presence of a solvent and a catalyst added if necessary.

The content of the component (a1) in the composition for buffer layer formation is from From the viewpoint of forming a buffer layer having a penetration depth (X) within the above range, it is preferably 10 to 70% by mass, and more preferably 20 to 60 relative to the total amount (100% by mass) of the buffer layer forming composition The mass% is even better at 25~55 mass%, and still better at 30~50 mass%.

(Polymer compound (a2) having an alicyclic group or heterocyclic group having 6 to 20 ring-forming atoms)

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

The number of ring-forming atoms of the alicyclic group or heterocyclic group possessed by the component (a2) is preferably 6-20, but more preferably 6-18, even more preferably 6-16, and even more preferably 7 ~12.

Examples of the atoms forming the ring structure of the heterocyclic group include carbon Son, nitrogen atom, oxygen atom, sulfur atom, etc.

Still, in the present invention, the number of ring-forming atoms refers to the number of atoms constituting the ring itself of the compound in which the atoms are bonded into a ring structure, and atoms that do not constitute a ring (such as hydrogen atoms bonded to atoms constituting the ring) ), or the atoms included in the substituent when the ring is substituted with a substituent, are not included in the number of ring-forming atoms.

As a specific component (a2), for example, isobornyl (method Group) acrylate, dicyclopentenyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, Aliphatic group-containing (meth)acrylates such as adamantane (meth)acrylate; heterocyclic groups such as tetrahydrofurfuryl (meth)acrylate, morpholine (meth)acrylate, etc. ) Acrylate; etc.

Still, the component (a2) can be used alone or in combination of two or more.

Among these, (meth)acrylates containing an alicyclic group are preferred, and isobornyl (meth)acrylates are more preferred.

The content of the component (a2) in the composition for buffer layer formation is from From the viewpoint of forming the buffer layer having the indentation depth (X) within the above range, and from the viewpoint of improving the film-forming properties of the resulting buffer layer forming composition, the total amount (100% by mass) relative to the buffer layer forming composition It is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, even more preferably 25 to 55% by mass, and still more preferably 30 to 50% by mass.

(Polymeric compound with functional group (a3))

The component (a3) used in the present invention contains a hydroxyl group, an epoxy group, and an amide The polymerizable compound having a functional group such as a group and an amine group is preferably a compound having at least one (meth)acryloyl group.

The component (a3) has good compatibility with the component (a1), and the viscosity of the composition for forming a buffer layer can be adjusted to an appropriate range, and the elastic modulus of the buffer layer formed of the composition can also be adjusted to an appropriate range. Therefore, by using this component (a3), a buffer layer having a squeezing depth (X) within the above range can be formed.

Examples of the component (a3) include hydroxyl-containing (meth)acrylates, epoxy-containing (meth)acrylates, amide group-containing compounds, and amine group-containing (meth)acrylates.

Examples of hydroxyl-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3- Hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenylhydroxypropyl (meth)acrylate, etc.

Examples of epoxy group-containing (meth)acrylates include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether.

Examples of the compound containing an amide group include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hydroxymethyl (Meth)acrylamide, N-methylolpropane (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acryl Acylamine, etc.

Examples of the amine group-containing (meth)acrylate include, for example, a (meth)acrylate containing a first-stage amine group, and a (meth)acrylic acid containing a second-stage amine group. Ester, (meth)acrylic acid esters containing third-level amine groups, etc.

Still, the component (a3) can be used alone or in combination of two or more.

Among these, the formation depth (X) becomes the above range From the viewpoint of the buffer layer, the hydroxyl group-containing (meth)acrylate is preferable, and the hydroxyl group-containing (meth)acrylate having an aromatic ring such as phenylhydroxypropyl (meth)acrylate is more preferable. .

The content of the component (a3) in the buffer layer forming composition is from From the viewpoint of forming the buffer layer having the indentation depth (X) within the above range, and from the viewpoint of improving the film-forming properties of the resulting buffer layer forming composition, the total amount (100% by mass) relative to the buffer layer forming composition It is preferably 5 to 40% by mass, more preferably 7 to 35% by mass, even more preferably 10 to 30% by mass, and still more preferably 13 to 25% by mass.

Moreover, the content ratio of the component (a2) to the component (a3) in the composition for buffer layer formation [(a2)/(a3)] is preferably 0.5 to 3.0, more preferably 1.0 to 3.0, and even more preferably 1.3~3.0, and even better is 1.5~2.8.

If the content ratio is 0.5 or more, the resulting buffer layer forming composition can have good film-forming properties. In addition, if the content ratio is 3.0 or less, a buffer layer having a penetration depth (X) within the above range can be formed.

(Polymerizable compounds other than components (a1) to (a3))

The buffer layer forming composition may contain other polymerizable compounds other than the above-mentioned components (a1) to (a3) in a range that does not impair the effects of the present invention.

Examples of other polymerizable compounds include carbon atoms having 1 to 20 Alkyl (meth)acrylates of alkyl; styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, N-vinylcaprolactam Vinyl compounds such as amines: etc.

Still, these other polymerizable compounds can be used alone or in combination of two or more.

Other polymerizable compounds in the composition for forming the buffer layer The content of is preferably 0-20% by mass, more preferably 0-10% by mass, even more preferably 0-5% by mass, and still more preferably 0-2% by mass.

(Photopolymerization initiator)

In the composition for forming a buffer layer, when the buffer layer is formed, it is preferable to further contain a photopolymerization initiator from the viewpoint of shortening the polymerization time by light irradiation and reducing the light irradiation amount.

Examples of the photopolymerization initiator include photopolymerization initiators such as benzoin compounds, acetophenone compounds, acyl phosphinoxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds. Photosensitizers such as amines and quinones, more specifically, for example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin Ether, benzoin ethyl ether, benzoin isopropyl ether, etc.

These photopolymerization initiators can be used alone or in combination of two or more.

The content of the photopolymerization initiator in the composition for forming the buffer layer The amount is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass relative to 100 parts by mass of the total energy ray polymerizable compound.

(Other additives)

The buffer layer-forming composition may contain other additives within a range that does not impair the effects of the present invention.

Examples of other additives include antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, and dyes.

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, more preferably 0.1 to 3, relative to 100 parts by mass of the total energy ray polymerizable compound. Quality parts.

(Resin component)

The buffer layer-forming composition may contain a resin component within a range that does not impair the effects of the present invention.

Examples of the resin component include polyene thiol resins, polyolefin resins such as polybutene, polybutadiene, and polymethylpentene, and thermoplastic resins such as styrene copolymers.

The content of these resin components in the buffer layer forming composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, even more preferably 0 to 5% by mass, and still more preferably 0 to 2% by mass.

<adhesive layer>

As the adhesive that forms the adhesive layer of the adhesive sheet of the present invention, the type of the adhesive is not limited if it is a moderately releasable adhesive with respect to an object such as a semiconductor wafer.

Examples of such adhesives include acrylic adhesives, urethane adhesives, silicone adhesives, rubber adhesives, polyester adhesives, energy ray-curable adhesives, and heating foams. Type adhesive, water swelling type adhesive, etc.

These adhesives can be used alone or in combination of two or more.

Still, as an energy ray-curable adhesive, for example, The adhesive described in Japanese Patent Laid-Open No. 60-196956, Japanese Patent Laid-Open No. 60-223139, etc. is preferably an ultraviolet curing adhesive.

The mass average molecular weight (Mw) of the resin contained in these adhesives is preferably 20,000 to 1.5 million, more preferably 50,000 to 1.2 million, and still more preferably 100,000 to 1 million.

In addition, if necessary, these adhesives may contain energy ray-curable resins, hardeners, crosslinking agents, photopolymerization initiators, antioxidants, softeners (plasticizers), fillers, rust inhibitors, Pigments, dyes, etc.

Although the thickness of the adhesive layer can be the semiconductor The conditions of the shape, surface condition and polishing method of the bumps of the wafer are appropriately set, but it is preferably 5 to 500 μm, more preferably 10 to 300 μm, and still more preferably 15 to 100 μm.

<easy adhesion layer>

The adhesive sheet of the present invention can be used between the rigid substrate and the buffer layer, and between the rigid substrate and the adhesive layer from the viewpoint of improving the adhesion between the rigid substrate and the buffer layer and/or the adhesive layer At least one side is provided with an easy adhesion layer.

The composition for forming an easy-adhesive layer for forming an easy-adhesive layer is not particularly limited, but examples thereof include polyester resins, urethane resins, polyester urethane resins, and acrylic resins. Resin and other components.

In addition, if necessary, the composition for forming an easy-adhesive layer may contain a crosslinking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, a rust inhibitor, a pigment, a dye, and the like.

The thickness of the easy-adhesion layer is preferably 0.01 to 10 μm, and more preferably 0.03 to 5 μm.

Still, the thickness of the easy-adhesive layer is smaller than that of the rigid substrate, and the material is also softer. Therefore, the Young's modulus of the rigid substrate with the easy-adhesive layer and the rigid substrate without the easy-adhesive layer The difference in Young's modulus of the material is extremely small.

Therefore, in the present invention, "Young's modulus of a rigid substrate provided with an easy-adhesion layer" = "Young's modulus of a rigid substrate" is considered.

<peel sheet>

Examples of the peeling sheet used in the present invention include a peeling sheet that is peeled on both sides, a peeling sheet that is peeled on one side, and the like, and a peeling agent is applied to the surface of the substrate for peeling sheets.

The substrate for the release sheet is preferably a resin film. Examples of the resin constituting the resin film include polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate. Polyester resin film such as polyester resin, polypropylene resin, polyethylene resin, etc. Wait.

Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins Wait.

Although the thickness of the peeling sheet is not particularly limited, it is preferably 10 to 200 μm, and more preferably 20 to 150 μm.

[Manufacturing method of adhesive sheet]

The manufacturing method of the adhesive sheet of the present invention is not particularly limited, and can be manufactured by a well-known method.

For example, if the buffer layer provided on the release sheet and the adhesive layer provided on the release sheet can be bonded to the surface of the rigid substrate, the adhesive sheet 1b shown in FIG. 1(b) can be manufactured.

Moreover, if two peeling sheets can be removed from the adhesive sheet 1b shown in FIG. 1(b), the adhesive sheet 1a shown in FIG. 1(a) can be obtained.

Furthermore, after forming an easy-adhesion layer on the surface of the rigid substrate used in advance, if the buffer layer provided on the release sheet and the adhesive layer provided on the release sheet can be bonded together, it can be manufactured as shown in FIG. 1(a)示的粘片1c。 The adhesive sheet 1c.

As a buffer layer or adhesive layer formed on the release sheet It is possible to form a buffer layer or an adhesive by directly applying a composition for forming a buffer layer or an adhesive using a well-known coating method to form a coating film, drying the coating film and/or irradiating energy rays Layer on the peeling sheet.

Examples of the coating method 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.

In addition, in order to improve the applicability, the buffer layer forming group The finished product or adhesive, blended with organic solvents, can be applied to the release sheet as a solution.

Examples of the organic solvent used include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. Wait.

Still, these organic solvents may directly use the organic solvents used in the synthesis of the components contained in the composition, or may add one or more organic solvents other than these.

The composition for forming a buffer layer for forming a coating film contains The energy ray polymerizable compound can form a buffer layer by irradiating the energy film with the energy ray to harden it.

The hardening treatment can completely harden it once, or it can be divided into multiple times to harden it. That is, after the coating film on the peeling sheet is completely cured to form a buffer layer, it is attached to a rigid substrate, the coating film is not completely cured, and a semi-hardened buffer layer forming film is formed, and the buffer layer can be formed After the film is attached to the rigid substrate, the energy beam is irradiated again to completely harden it to form a buffer layer.

As the energy ray irradiated by the hardening treatment, purple is preferred Outside.

The irradiation amount of energy rays can be appropriately changed according to the type of energy rays. For example, when using ultraviolet rays, the illuminance of the irradiated ultraviolet rays is preferably 50 to 500 mW/cm ² , more preferably 100 to 340 mW/cm ² , and the irradiation amount of ultraviolet rays is preferably 80 to 2500 mJ/cm ² , more preferably 100 to 2000mJ/cm ² .

The adhesive sheet of the present invention is used in grinding to complete the manufacture of wafers In this case, it is suitable as a BG sheet for protecting the surface side of the wafer.

As a method of manufacturing a ground-finished wafer using the adhesive sheet of the present invention, for example, a method of manufacturing a ground-finished wafer having the following steps (1A) to (3A) is preferable.

Step (1A): the step of attaching the adhesive layer of the adhesive sheet of the present invention to the surface side of the wafer to obtain a wafer with a buffer layer

Step (2A): the step of placing the buffer layer of the wafer with buffer layer obtained in step (1A) on the chuck base of the grinder

Step (3A): grinding the inside of the wafer without the buffer layer of the wafer with the buffer layer, and obtaining the step of grinding the completed wafer

The adhesive sheet of the present invention is excellent in foreign substance adsorption. Therefore, in the step (2A) of the wafer manufacturing method of the above grinding, even if a foreign object is attached to the chuck base, the buffer layer absorbs the thickness of the foreign object, which can suppress the swelling of the inner surface of the wafer that causes the presence of the foreign object .

As a result, according to the above-described manufacturing method, it is possible to prevent the cracking of the wafer due to the cutting process due to the presence of the foreign substance, and it is possible to manufacture a wafer with a high yield and a thin film after grinding.

In addition, the adhesive sheet of the present invention is also suitable for use The BG sheet of the semiconductor wafer manufacturing method by the first dicing method.

As a method of manufacturing a semiconductor wafer using the adhesive sheet of the present invention, for example, a method of manufacturing a semiconductor wafer having the following steps (1B) to (3B) is preferable.

Step (1B): On the surface, the adhesive layer of the adhesive sheet of the present invention is attached to the surface side of the wafer provided with a specific configuration in a groove of a specific depth And the steps to get the wafer with buffer layer

Step (2B): the step of placing the buffer layer of the wafer with buffer layer obtained in step (1B) on the chuck base of the grinder

Step (3B): The step of grinding the inside of the wafer without the buffer layer to a specific thickness and dividing it into individual wafers

As described above, the buffer layer included in the adhesive sheet of the present invention is excellent in foreign matter adsorption, and can prevent the foreign matter adhering to the chuck base from being broken due to cutting due to cutting. As a result, according to the above-mentioned manufacturing method, a semiconductor wafer with a high yield and a thin film can be manufactured.

[Example]

The mass average molecular weight (Mw) of each component used in the following examples and comparative examples, and the Young's modulus of the rigid substrate are the values measured by the methods described below.

<Mass average molecular weight (Mw)>

Using a gel permeation chromatography apparatus (manufactured by Tosoh Corporation, product name "HLC-8020"), the measurement was performed under the following conditions, and the value measured in standard polystyrene conversion was used.

(Measurement conditions)

. Column: "TSK guard column HXL-H" "TSK gel GMHXL (×2)" "TSK gel G2000HXL" (all made by Tosoh Corporation)

. Column temperature: 40℃

. Expand solvent: Tetrahydrofuran

. Flow rate: 1.0mL/min

<Young's modulus of rigid substrate>

The Young's modulus of the rigid substrate is subjected to a tensile test using a tensile tester, and is calculated from the obtained graph of tensile strength and elongation. Specifically, the PET film with an easy-adhesive layer on both sides produced in Manufacturing Example 3 was cut into a size of 15 mm in width × 150 mm in length, and stretched so that the stretchable portion became 100 mm. Compression testing machine (manufactured by A & D, product name "Tensilon"). The measurement was performed at a test speed of 200 mm/min, and the Young's modulus was calculated from the slope at the origin of the obtained graph.

Manufacturing Example 1 (Synthesis of urethane acrylate oligomer (UA-1))

The terminal isocyanate urethane prepolymer obtained by reacting polyester diol and isophorone diisocyanate is reacted with 2-hydroxyethyl acrylate to obtain a mass average molecular weight (Mw) of 5000 2-functional urethane acrylate oligomer (UA-1).

Manufacturing Example 2 (Preparation of peeling sheet with adhesive layer)

Blending 100 parts by mass has a composition derived from n-butyl acrylate (BA), methyl methacrylate (MMA) and 2-hydroxyethyl acrylate (2HEA) Unit of acrylic copolymer (BA/MMA/2HEA=52/20/28 (mass %), Mw=500,000), 6 parts by mass of multifunctional urethane acrylate ultraviolet curable resin, 1 part by mass Diisocyanate hardener, and 1 part by mass of bis(2,4,6-trimethylbenzyl)phenylphosphine oxide as photopolymerization initiator, diluted with methyl ethyl ketone to adjust the solid content concentration 32% by mass solution of adhesive.

And the peeling sheet (made by Lintec, trade name "SP-PET381031", silicone peeling polyethylene terephthalate (PET) film, thickness: 38 μm) on the peeled surface, apply the above The solution of the adhesive composition was dried to prepare a peeling sheet with an adhesive layer and an adhesive layer having a thickness of 20 μm.

Manufacturing Example 3 (Production of PET film with easy adhesion layer on both sides)

Contrary to the first easy bonding layer of a PET film (made by Toyobo Co., Ltd., trade name "PET50 A-4100") with a thickness of 50 μm and an easy bonding layer (the first easy bonding layer) provided on one side On the side surface, polyester anchor coating agent (Arakawa Chemical Co., Ltd.) was applied and dried, and a second easy adhesion layer with a thickness of 2 μm was provided to obtain an easy adhesion on both sides with a thickness of 52 μm. PET film. The Young's modulus of the PET film with an adhesive layer on both sides is 2500 MPa.

Examples 1-2, Comparative Examples 1-4 (1) Preparation of the composition for buffer layer formation

As energy ray polymerizable compounds, ethyl urethane acrylate oligomer (UA-1), isobornyl acrylate (IBXA), phenyl hydroxypropyl acrylate (HPPA) synthesized in Production Example 1 , Blended at the blending amount described in Table 1, and further blended 2.0 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure184") as a photopolymerization initiator, 0.2 parts by mass of phthalide A cyanine pigment is used to prepare a composition for forming a buffer layer.

(2) Production of adhesive sheet

Apply the above to the peeled sheet (polyethylene terephthalate (PET) film made by Lintec, trade name "SP-PET381031", silicone peeled polyethylene terephthalate (PET) film, thickness: 38 μm) The composition for buffer layer formation forms a coating film. The coating film was irradiated with ultraviolet rays to semi-harden the coating film to form a buffer layer forming film with a thickness of 43 μm.

Still, the aforementioned ultraviolet irradiation uses a belt conveyor type ultraviolet irradiation device (product name "ECS-401GX", manufactured by Eye Graphics) and a high-pressure mercury lamp (H04-L41 manufactured by Eye Graphics: H04-L41), with a lamp height of 150 mm and a lamp The output was performed under irradiation conditions of 3 kW (converted output 120 mW/cm), illuminance of light wavelength 365 nm, 120 mW/cm ² , and irradiation amount of 100 mJ/cm ² .

Then, the surface of the buffer layer forming film formed by bonding and the first easy bonding layer of the PET film with an easy bonding layer on both sides produced in Manufacturing Example 3 were irradiated with ultraviolet rays again from the peeling sheet side on the buffer layer forming film, so that buffer The layer-forming film was completely cured to form a buffer layer with a thickness of 43 μm.

Still, the above-mentioned ultraviolet irradiation uses the above-mentioned ultraviolet irradiation device and high-pressure mercury lamp, with a lamp height of 150 mm, a lamp output of 3 kW (converted output of 120 mW/cm), an illumination of 160 mW/cm ² with a light wavelength of 365 nm, and an irradiation amount of 500 mJ/cm ² Under conditions.

Next, on the second easy-adhesive layer of the PET film with the easy-adhesive layer on both sides, stick the adhesive layer of the peeling sheet with the adhesive layer prepared in Manufacturing Example 2 to produce an adhesive layer with FIG. 1(d) The sheet 1d is an adhesive sheet of the same composition.

For the adhesive sheet made as above, various physical properties The measurement and evaluation of the characteristics were carried out by the method described below. The results are shown in Table 1.

<Determination of Extrusion Depth (X)>

Use a dynamic microhardness tester (manufactured by Shimadzu Corporation, product name "DUH-W201S") and a triangular cone-shaped indenter with a tip radius of curvature of 100 nm and an inter-angle of 115° as the indenter at 23°C, 50 Measured in %RH (relative humidity) environment.

Specifically, on the glass plate of the dynamic microhardness tester, the peeling sheet on the buffer layer of the prepared adhesive sheet is removed, the buffer layer is arranged as shown, and for the buffer layer, the above-mentioned triangular cone-shaped indenter is pressed The tip is squeezed in at a rate of 10 μm/minute, and the squeeze depth (X) is measured when the compression load reaches 2 mN.

<Measurement of the maximum value of tan δ of the buffer layer>

In the same manner as above, a buffer layer forming film with a thickness of 500 μm composed of the buffer layer forming compositions used in the individual examples and comparative examples was formed on the first release sheet, and then on the buffer layer forming film Attach the second peeling sheet. It is to be noted that the first and second peeling sheets used are the same as those used in the above examples and comparative examples.

Furthermore, ultraviolet rays were irradiated from the side of the first peeling sheet again to completely harden the buffer layer-forming film to form a test buffer layer having a thickness of 500 μm. Still, the above-mentioned ultraviolet irradiation uses the above-mentioned ultraviolet irradiation device and high-pressure mercury lamp, with a lamp height of 150 mm, a lamp output of 3 kW (converted output of 120 mW/cm), an illumination of 160 mW/cm ² with a light wavelength of 365 nm, and an irradiation amount of 500 mJ/cm ² Under conditions.

After removing the peeling sheet on both sides of the prepared test buffer layer, using a test piece cut into a specific size, a dynamic viscoelastic device (manufactured by Orientec, product name "Rheovibron DDV-II-EP1"), measured at the frequency 11Hz, loss elasticity and storage elasticity in temperature range -20~150℃.

Calculate the value of "loss elasticity/storage elasticity" at each temperature as the tanδ at that temperature, and record the maximum value of tanδ in the range of -5 to 120°C as the "maximum value of tan δ of the buffer layer" in Table 1. .

<Evaluation of Absorbency of Foreign Matter (Whether Wafer Was Cracked)

On the surface of the silicone wafer with a thickness of 700 μm, remove the adhesive layer from the peeled sheet on the adhesive layer of the manufactured adhesive sheet, so that Use BG tape with a plastic sealing machine (made by Lintec, product name "Plastic Packaging Machine RAD-3500m/12") for bonding.

After attaching the adhesive sheet to the silicone wafer, remove the peeling sheet on the buffer layer, on the surface of the exposed buffer layer, as a pseudo foreign body, attach the tape at 5 places (on a PET film with a thickness of 6 μm, set by a thickness of 3 μm Adhesive layer composed of acrylic adhesive, vertical: 1cm, horizontal: 2cm, thickness: 9μm).

Furthermore, using a wafer inner surface grinding machine (manufactured by DISCO, product name "DFG-8540"), the inner surface of the adhesive sheet to which the silicone wafer was never attached was ground until the thickness became 100 μm.

After grinding, visually observe whether the silicone wafer is cracked or not, and evaluate the foreign matter adsorption of the adhesive sheet based on the following criteria.

A: No cracking of the wafer is observed, and the foreign matter of the adhesive sheet is well adsorbed.

F: Cracking of the wafer was observed, and the foreign matter of the adhesive sheet was poorly adsorbed.

From Table 1, it is understood that the adhesive sheets produced in Examples 1 to 2 are excellent in foreign substance adsorption.

In addition, the adhesive sheets produced in Comparative Examples 1 to 4 are used in the grinding process of wafers, and the foreign substance adsorption is poor, which results in the cracking of the wafers after cutting.

[Industry availability]

The adhesive sheet of the present invention is excellent in foreign substance adsorption.

Therefore, the adhesive sheet of the present invention can be suitably used as a BG sheet for protecting the surface side of a semiconductor wafer, for example, in the grinding process of a semiconductor wafer. When used in this application, it can effectively prevent the semiconductor wafer from cracking.

1a, 1b, 1c, 1d

11‧‧‧Rigid substrate

12‧‧‧buffer layer

13‧‧‧Adhesive layer

14a, 14b ‧‧‧ peel sheet

15a, 15b‧‧‧easy adhesion layer

Claims (8)

An adhesive sheet having a rigid substrate with a Young's modulus of 1000 MPa or more, a buffer layer provided on one side of the rigid substrate, and an adhesive layer provided on the other side of the rigid substrate, and The adhesive sheet used in the manufacture of semiconductor wafers by the first dicing method is characterized in that the aforementioned buffer layer is a layer formed of a composition for forming a buffer layer containing an energy ray polymerizable compound, and the tip curvature radius is 100 nm and The tip of the triangular hammer-shaped indenter with an inter-angle of 115° is pressed at a speed of 10 μm/minute at the speed of 10 μm/minute, and the compression depth (X) necessary for the compression load to reach 2 mN is 2.5 μm or more. The composition used as the aforementioned energy ray polymerizable compound is a polymerizable compound (a2) containing urethane (meth)acrylate (a1), an alicyclic group or heterocyclic group having 6 to 20 ring forming atoms ), and the polymerizable compound (a3) having a functional group, the content ratio of the component (a2) to the component (a3) in the aforementioned buffer layer forming composition [(a2)/(a3)] is 1.3 to 3.0, The maximum value of the dynamic viscoelastic tan δ of the aforementioned buffer layer at -5 to 120°C is 1.2 or more. The adhesive sheet according to claim 1, wherein the content ratio of the component (a2) to the component (a3) in the aforementioned buffer layer forming composition [(a2)/(a3)] is 1.5 to 2.8. The adhesive sheet according to claim 1 or 2, wherein the component (a2) is an alicyclic group-containing (meth)acrylate. The adhesive sheet according to claim 1 or 2, wherein the component (a3) is a hydroxyl-containing (meth)acrylate. The adhesive sheet according to claim 1 or 2, wherein the thickness of the aforementioned buffer layer is 5 to 100 μm. The adhesive sheet according to claim 1 or 2, wherein at least one of the rigid substrate and the buffer layer and the rigid substrate and the adhesive layer have an easy-adhesion layer. The adhesive sheet of claim 1 or 2 is used as a back grinding sheet to protect the surface side of the semiconductor wafer during the cutting process of the semiconductor wafer. A method for manufacturing a semiconductor wafer, comprising the following steps (1B) to (3B), step (1B): attaching the adhesive layer of the adhesive sheet according to any one of claims 1 to 7 to the surface Steps of obtaining a wafer with a buffer layer in a groove of a specific depth with a specific configuration of the surface side of a wafer provided with a specific configuration Step (2B): placing the buffer with a wafer with a buffer layer obtained in step (1B) Step of layering on the chuck base of the grinder (3B): a step of grinding the inside of the wafer of the buffer layer without the wafer with the buffer layer until it becomes a specific thickness and dividing it into individual wafers.

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