Adhesive sheet for back grinding, method for manufacturing semiconductor wafer, and base sheet

Abstract

Provided is an adhesive sheet for backgrinding that can increase the conformance of a substrate layer to protruding sections of a semiconductor wafer.　The present invention provides an adhesive sheet for backgrinding of a semiconductor wafer that has protruding sections, said adhesive sheet comprising a substrate layer and an adhesive agent layer that is provided on the substrate layer. The adhesive agent layer has an opening with a smaller diameter than the diameter of the semiconductor wafer, is adhered to an outer circumference section of the semiconductor wafer such that the protruding sections of the semiconductor wafer are positioned within the opening, and is configured such that, while the semiconductor wafer is adhered to the adhesive agent layer, the protruding sections are protected by the substrate layer. The substrate layer comprises a cushion layer and a barrier layer, and the oxygen permeability of the substrate layer as measured on the basis of JIS K 7162-2 (isopiestic method) at 25°C and 0% RH is 1000 ml / m2∙24h∙atm) or less.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet for back grinding, a method for manufacturing a semiconductor wafer using the same, and a base sheet.

Background Art

[0002] When processing a semiconductor wafer, an adhesive sheet is attached to protect it from damage. For example, in the back grinding process when processing a semiconductor wafer, an adhesive sheet is attached to protect the pattern surface of the semiconductor wafer. From the viewpoints of adhesiveness to a pattern surface having unevenness such as protruding electrodes (bumps) and reliability of pattern surface protection, followability (step followability) with respect to the unevenness of the pattern surface is required for the adhesive sheet.

[0003] In order to give the adhesive sheet followability, it is common in the market to thicken the adhesive layer or provide a flexible resin layer with cushioning properties between the base film and the adhesive. However, when the unevenness of the pattern surface is large, the risk of insufficient followability and adhesive residue increases.

[0004] In Patent Document 1, the adhesive sheet is configured to include an adhesive layer having an opening with a diameter smaller than the outer diameter of the semiconductor wafer on one side of the base layer, and the adhesive layer is attached to the outer peripheral portion of the semiconductor wafer so that the convex portion of the semiconductor wafer is disposed within the opening of the adhesive layer by vacuum mounting, and the convex portion is embedded in the base layer, thereby preventing adhesive residue and preventing a decrease in the protection function.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When the present inventors conducted intensive studies on the adhesive sheet disclosed in Patent Document 1, they found that the base material layer may not sufficiently follow the convex portions.

[0007] The present invention has been made in view of such circumstances, and provides an adhesive sheet for back grinding that can improve the followability of the base material layer to the convex portions of a semiconductor wafer.

Means for Solving the Problems

[0008] According to the present invention, the following inventions are provided. (1) An adhesive sheet for back grinding of a semiconductor wafer having convex portions, comprising a base material layer and an adhesive layer provided on the base material layer, wherein the adhesive layer has an opening smaller in diameter than the diameter of the semiconductor wafer, and the convex portions of the semiconductor wafer are adhered to the outer peripheral portion of the semiconductor wafer so as to be disposed within the opening, and the convex portions are protected by the base material layer in a state where the semiconductor wafer is adhered to the adhesive layer, the base material layer includes a cushion layer and a barrier layer, and the base material layer has an oxygen permeability measured based on JIS K 71 26 -2 (isobaric method) at 25 ° C and RH 0% of 1000 ml / (m 2 ·24 h·atm) or less, an adhesive sheet. (2) The adhesive sheet according to (1), wherein the barrier layer is provided on the side opposite to the adhesive layer when viewed from the cushion layer. (3) The adhesive sheet according to (1) or (2), wherein the convex portions are protected by being embedded in the base material layer. (4) The adhesive sheet according to any one of (1) to (3), wherein the semiconductor wafer is adhered to the adhesive layer under reduced pressure. (5) A method for manufacturing a semiconductor wafer using the adhesive sheet according to any one of (1) to (4), comprising a frame attaching step, a wafer attaching step, a heating step, a cutting step, a resin curing step, and a grinding step. In the frame attaching step, the adhesive sheet is attached to a ring frame. In the wafer attaching step, the adhesive sheet is attached to the outer peripheral portion of the semiconductor wafer under reduced pressure on the surface of the semiconductor wafer where the convex portions are provided. In the heating step, the base material layer is heated. In the cutting step, the adhesive sheet is cut along the outer periphery of the semiconductor wafer. In the resin curing step, after the wafer attaching step, the base material layer is brought into contact with a curable resin, and in this state, the curable resin is cured. In the grinding step, the back surface of the semiconductor wafer is ground. A method for manufacturing a semiconductor wafer. (6) A base material sheet comprising a cushion layer and a barrier layer, and having an oxygen permeability measured based on JIS K 71 26 -2 (isobaric method) of 1000 ml / (m 2 ·24 h·atm) or less. A base material sheet.

[0009] As a result of intensive studies by the present inventors, it has been found that by providing a barrier layer, the oxygen permeability of the base material layer is reduced, and thus the above problems have been discovered, leading to the completion of the present invention.

Brief Description of the Drawings

[0010]

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Figure 10

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described. Various characteristic matters shown in the following embodiments can be combined with each other. Also, the invention can be established independently for each characteristic matter.

[0012] 1. Adhesive Sheet The adhesive sheet 10 of one embodiment of the present invention will be described with reference to FIGS. 1 to 9. The adhesive sheet 10 of this embodiment includes a base material layer 1 and an adhesive layer 2 provided on the base material layer 1. This adhesive sheet 10 is used when grinding the back surface 4b of the semiconductor wafer 4 having the convex portions 5. Hereinafter, each configuration will be described.

[0013] 1-1. Base Material Layer 1 As shown in FIG. 1, the base material layer 1 includes a cushion layer 1a, a surface treatment layer 1b, and a barrier layer 1c. The surface treatment layer 1b is provided on the cushion layer 1a. The barrier layer 1c is preferably provided on the side opposite to the surface treatment layer 1b (or the adhesive layer 2) as viewed from the cushion layer 1a. The barrier layer 1c is preferably attached to the cushion layer 1a via an adhesive layer (not shown). The surface treatment layer 1b can be omitted.

[0014] The thickness of the entire base material layer 1 is preferably 50 to 400 μm, more preferably 100 to 350 μm, and even more preferably 200 to 300 μm. Specifically, this thickness is, for example, 50, 100, 150, 200, 250, 300, 350, 400 μm, and may also be within the range between any two of the numerical values exemplified herein.

[0015] <Cushion layer 1a> The cushion layer 1a is a layer for protecting the convex portion 5 of the semiconductor wafer 4 shown in FIG. 2. The cushion layer 1a is preferably composed of a thermoplastic resin. The composition of the thermoplastic resin is not particularly limited, but monomers and / or composites such as a ternary copolymer of ethylene-methacrylic acid-acrylic acid ester, an ethylene-methacrylic acid copolymer, an ethylene-acrylic acid copolymer, etc., and an ionomer resin obtained by crosslinking the carboxyl groups with metal ions such as sodium ions, lithium ions, and magnesium ions, a soft polypropylene resin blended with styrene-butadiene copolymer rubber, styrene-butadiene-styrene block copolymer rubber, styrene-isoprene-styrene block copolymer rubber, ethylene-propylene rubber, etc., low-density polyethylene, ethylene-propylene block copolymer, ethylene-propylene random copolymer, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-1-octene copolymer, polybutene, etc. can be used. Among them, ionomer resin is preferred.

[0016] The proportion Ra (mass %) of the (meth)acrylic monomer unit in the resin constituting the cushion layer 1a is preferably lower than the proportion Rb (mass %) of the (meth)acrylic monomer unit in the acrylic resin constituting the surface treatment layer 1b. In this case, since the adhesion between the adhesive layer 2 composed of the acrylic resin composition and the surface treatment layer 1b is higher than the adhesion between the adhesive layer 2 and the cushion layer 1a, the technical significance of providing the surface treatment layer 1b is remarkable. The value of (Rb - Ra) is, for example, 10 to 100 mass %, preferably 30 to 100 mass %. Specifically, this value is, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 mass %, and may also be within the range between any two of the numerical values exemplified herein.

[0017] The storage elastic modulus E'a of the cushion layer 1a at 180°C is preferably lower than the storage elastic modulus E'b of the surface treatment layer 1b at 180°C. When the storage elastic modulus E'a of the cushion layer 1a is low under high-temperature conditions, there is a tendency for the cushion layer 1a to be excessively softened during heating, strongly adhere to the wafer, and be difficult to peel off. By providing the surface treatment layer 1b, the occurrence of such problems is suppressed. Therefore, when the storage elastic modulus E'a is lower than the storage elastic modulus E'b, the technical significance of providing the surface treatment layer 1b is remarkable. When the measurement of the storage elastic modulus E'a is impossible due to the melting of the cushion layer 1a, for convenience, the storage elastic modulus E'a is set to 0.

[0018] The weight average molecular weight (Mw) of the above thermoplastic resin is preferably 10,000 to 1,000,000, more preferably 50,000 to 500,000. The weight average molecular weight (Mw) is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

[0019] The softening temperature (JIS K7206) of the above-mentioned thermoplastic resin is preferably 45 to 200 °C, more preferably 55 to 150 °C. Specifically, this softening temperature is, for example, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 °C, and it may also be within the range between any two of the values exemplified herein.

[0020] The melting point (JIS K7121) of the above-mentioned thermoplastic resin is preferably 60 to 200 °C, more preferably 80 to 150 °C. Specifically, this melting point is, for example, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 °C, and it may also be within the range between any two of the values exemplified herein.

[0021] The melt flow rate (MFR) (JIS K7210, 125 °C / 10.0 kg load) of the above-mentioned thermoplastic resin is preferably 0.2 to 30 g / 10 min, more preferably 0.3 to 20 g / 10 min.

[0022] When the thermoplastic resin has the above physical properties, the cushion layer 1a is appropriately softened as the base material layer 1 is heated, so that the convex portion 5 is easily embedded in the base material layer 1.

[0023] The thickness of the cushion layer 1a is preferably 50 to 400 μm, more preferably 100 to 350 μm, and even more preferably 200 to 300 μm. Specifically, this thickness is, for example, 50, 100, 150, 200, 250, 300, 350, 400 μm, and it may also be within the range between any two of the values exemplified herein.

[0024] <Surface treatment layer 1b> The surface treatment layer 1b is formed of an acrylic resin composition containing an acrylic resin and is crosslinked by light irradiation or heating. When the adhesive layer 2 is formed directly on the cushion layer 1a, peeling of the adhesive layer 2 may occur if the adhesion between the cushion layer 1a and the adhesive layer 2 is not good. However, by forming the surface treatment layer 1b on the cushion layer 1a and then forming the adhesive layer 2 with an acrylic resin composition, peeling of the adhesive layer 2 can be suppressed.

[0025] Also, in order to enhance the adhesion between the cushion layer 1a and the adhesive layer 2, when the cushion layer 1a is subjected to corona discharge treatment and this cushion layer 1a is attached to the semiconductor wafer, the adhesive force between the cushion layer 1a and the semiconductor wafer may become too high, making it difficult to peel the semiconductor wafer from the cushion layer 1a. Therefore, in this embodiment, the surface treatment layer 1b is formed on the cushion layer 1a and the surface treatment layer 1b is attached to the semiconductor wafer. As described above, since the surface treatment layer 1b has excellent adhesion to the adhesive layer 2 without performing corona discharge treatment, there is no need to perform corona discharge treatment on the surface treatment layer 1b. For this reason, by providing the surface treatment layer 1b, it becomes possible to reduce the adhesive force between the base material layer 1 and the semiconductor wafer.

[0026] Specifically, by providing the surface treatment layer 1b, a semiconductor wafer obtained by bonding the base material layer 1 of a test piece cut out from the adhesive sheet 10 can be heated in an atmosphere of 100°C for 1 minute and then cooled to room temperature, and the adhesive force measured in accordance with JIS Z0237 at 23°C between the base material layer 1 and the semiconductor wafer can be made less than 6 N / 200 mm. In this case, it is preferable that the adhesive force between the base material layer 1 and the semiconductor wafer is smaller than the adhesive force between the adhesive layer 2 and the semiconductor wafer. This adhesive force is, for example, 0 to 5.9 N / 200 mm, more preferably 0.1 to 3 N / 200 mm, and even more preferably 0.5 to 2 N / 200 mm. Specifically, this adhesive force is, for example, 0, 0.1, specifically, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 5.9 N / 200 mm, and may also be within the range between any two of the values exemplified herein. Also, the adhesive force under the above measurement conditions before heating is preferably 5 N / 200 mm or less. This adhesive force is, for example, 0 to 5 N / 200 mm, specifically, for example, 0, 0.1, 0.5, 1, 2, 3, 4, 5 N / 200 mm, and may also be within the range between any two of the values exemplified herein.

[0027] The acrylic resin means a resin in which the proportion of (meth)acrylic monomer units contained in the resin is 50% by mass or more. The (meth)acrylic monomer means a compound having a (meth)acryloyl group. The (meth)acrylic monomer is preferably monofunctional.

[0028] Examples of the (meth)acrylic monomer include (meth)acrylic acid and / or (meth)acrylic acid ester. Examples of the (meth)acrylic acid ester include alkyl (meth)acrylate, hydroxyalkyl (meth)acrylate, (meth)acrylate having a cyclic ether skeleton, and the like. These may be used alone or in combination of multiple types.

[0029] As the alkyl (meth)acrylate, the (meth)acrylate represented by the following general formula (A) is preferable.

[0030] (A) Z-O-R (In the formula, Z represents a (meth)acryloyl group, and R represents an alkyl group having 1 to 10 carbon atoms.)

[0031] Examples of such alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, and the like.

[0032] Examples of hydroxyalkyl (meth)acrylates include 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and glycerol mono(meth)acrylate.

[0033] Examples of (meth)acrylates having a cyclic ether skeleton include glycidyl (meth)acrylate, furfuryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 3-ethyl-3-oxetanylmethyl (meth)acrylate, (2-methyl-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, γ-butyrolactone (meth)acrylate, dioxolane (meth)acrylate, dioxane glycol di(meth)acrylate, oxetane (meth)acrylate, and the like. One or more of these can be used. Among the cyclic ether skeletons, a 5- to 6-membered ring is preferred. The cyclic ether skeleton preferably has 1 oxygen atom. The cyclic ether skeleton preferably has 2 to 5 carbon atoms. Among the (meth)acrylates having a cyclic ether skeleton, glycidyl (meth)acrylate is preferred.

[0034] The acrylic resin may contain only (meth)acrylic monomer units, or may contain other monomer units other than (meth)acrylic monomer units. Examples of the other monomer units include olefins such as ethylene and propylene, aliphatic vinyls such as vinyl acetate, and aromatic vinyls such as styrene.

[0035] The proportion of the (meth)acrylic monomer units in the acrylic resin constituting the surface treatment layer 1b is, for example, 50 to 100% by mass, specifically, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% by mass, and may be within the range between any two of the numerical values exemplified herein.

[0036] The acrylic resin can be obtained by polymerizing a monomer mixture containing the above monomers.

[0037] The acrylic resin composition preferably contains a crosslinking agent. By the reaction of the acrylic resin and the crosslinking agent, the acrylic resin is crosslinked. Examples of the crosslinking agent include acrylate-based crosslinking agents, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, etc. These may be used alone or in combination of two or more.

[0038] Examples of the acrylate-based crosslinking agent include compounds having a plurality (e.g., 2) of (meth)acryloyl groups, specifically, 1,9-nonanediol diacrylate, 1,6-hexanediol diacrylate, triethylene glycol diacrylate, polytetramethylene glycol diacrylate, neopentyl glycol diacrylate, 3-methyl-1,5-pentanediol diacrylate, etc.

[0039] Examples of the isocyanate-based crosslinking agent include polyvalent isocyanate compounds such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, lysine isocyanate, and derivatives thereof (adducts, biuret compounds, isocyanurate compounds). These may be used alone or in combination of two or more.

[0040] The compounding amount of the crosslinking agent relative to 100 parts by mass of the acrylic resin is, for example, 0.5 to 30 parts by mass, preferably 4 to 25 parts by mass, and more preferably 7 to 20 parts by mass. Specifically, this compounding amount is, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30 parts by mass, and may also be within the range between any two of the numerical values exemplified herein.

[0041] The acrylic resin is crosslinked by light irradiation or heating.

[0042] In the case of crosslinking by light irradiation, the acrylic resin composition preferably contains a photopolymerization initiator. Specific examples of the photopolymerization initiator are not particularly limited, but benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, etc. can be used, and acetophenone-based photopolymerization initiators are preferred.

[0043] Specific examples of acetophenone-based photoinitiators include 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methoxyacetophenone, and the like.

[0044] The acrylic resin preferably has an Mw of 300,000 to 2,000,000 before crosslinking, more preferably 450,000 to 800,000. If the Mw is too low, the heat resistance may be insufficient. If the Mw is too high, the viscosity becomes too high and coating becomes difficult, which may lead to a decrease in productivity. Specifically, the Mw is, for example, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, 750,000, 800,000, 900,000, 1,000,000, 1,100,000, 1,200,000, 1,300,000, 1,400,000, 1,500,000, 1,600,000, 1,700,000, 1,800,000, 1,900,000, 2,000,000, and may be within the range between any two of the values exemplified here.

[0045] The acrylic resin preferably has a glass transition temperature (Tg) of -15 to 40°C before crosslinking, more preferably -10 to 30°C. Specifically, this Tg is, for example, -15, -10, -5, 0, 5, 10, 15, 20, 25, 30, 35, 40°C, and may be within the range between any two of the values exemplified here. The acrylic resin preferably has a Tg of 10 to 80°C after crosslinking, more preferably 20 to 70°C. Specifically, this Tg is, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80°C, and may be within the range between any two of the values exemplified here.

[0046] In this specification, Tg is measured as follows. Differential scanning calorimetry (DSC) measurement is performed in accordance with JIS K 7121:1987. Then, the intersection of the tangent of the baseline in the DSC curve and the tangent of the steep drop position of the endothermic region due to the glass transition is defined as Tg.

[0047] The surface treatment layer 1b preferably has a storage elastic modulus at 180°C of 1.0×10 4 Pa to 1.0×10 8 Pa. If this storage elastic modulus is too low, when the wafer is attached to the adhesive sheet 10 by heating the adhesive sheet 10, the surface treatment layer 1b becomes too soft. As a result, the surface treatment layer 1b may break along with the melting of the cushion layer 1a, and residues of the surface treatment layer 1b may remain on the wafer or the peelability may be impaired. If this storage elastic modulus is too high, the surface treatment layer 1b may be too hard, and the followability to the convex portion 5 of the base material layer 1 may deteriorate.

[0048] Specifically, for example, this storage elastic modulus is 1.0×10 4 Pa, 1.0×10 5 Pa, 1.0×10 6 Pa, 1.0×10 7 Pa, 1.0×10 8 Pa, and it may also be within the range between any two of the values exemplified here.

[0049] The thickness of the surface treatment layer 1b is, for example, 0.1 to 10 μm, preferably 0.5 to 5 μm, and more preferably 1 to 4 μm. When the surface treatment layer 1b has such a thickness, the effect of providing the surface treatment layer 1b is likely to be appropriately exhibited. Specifically, for example, this thickness is 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0 μm, and it may also be within the range between any two of the values exemplified here.

[0050] <Barrier layer 1c> The barrier layer 1c is a layer for reducing the oxygen permeability of the base material layer 1. When the base material layer 1 easily permeates air, outside air may enter the sealed space 2b through the base material layer 1, making it difficult to reduce the pressure in the sealed space 2b. As a result, there may be a problem that the base material layer 1 becomes difficult to follow the convex portion 5.

[0051] The barrier layer 1c is a layer with low oxygen permeability. When the oxygen permeability is low, usually the air permeability is also low. Therefore, by providing the barrier layer 1c, the intrusion of outside air into the sealed space 2b through the base material layer 1 is suppressed, and as a result, the effect that the base material layer 1 easily follows the convex portion 5 is achieved.

[0052] The barrier layer 1c has an oxygen permeability measured based on JIS K 71 26 -2 (isobaric method) at 25°C and 0% RH of the base material layer 1 of 1000 ml / (m 2 ·24h·atm) or less. In order to make the oxygen permeability of the base material layer 1 within such a range, it is preferable that the oxygen permeability of the barrier layer 1c alone under the same conditions is 1000 ml / (m 2 ·24h·atm) or less. In this case, the above effect is likely to be exhibited. The oxygen permeability of the base material layer 1 or the barrier layer 1c is, for example, 0 to 1000 ml / (m 2 ·24h·atm), preferably 0 to 500 ml / (m 2 ·24h·atm), and specifically, for example, 0, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 ml / (m 2 ·24h·atm), and it may also be within the range between any two of the values exemplified here.

[0053] The oxygen permeability of the barrier layer 1c under the above conditions is preferably lower than the oxygen permeability of the cushion layer 1a. The value of (oxygen permeability of the cushion layer 1a - oxygen permeability of the barrier layer 1c) is preferably 100 ml / (m 2 ·24h·atm) or more. This value is, for example, 100 to 3000 ml / (m 2 ·24h·atm), and specifically, for example, 100, 500, 1000, 1500, 2000, 2500, 3000 ml / (m 2 ·24h·atm), and it may also be within the range between any two of the values exemplified here.

[0054] The barrier layer 1c can be formed of any material capable of achieving the above oxygen permeability. From the viewpoint of being easily reduced in oxygen permeability, polyester (e.g., polyethylene terephthalate), polyimide, and polyamide are preferable.

[0055] The thickness of the barrier layer 1c is, for example, 5 to 50 μm, and preferably 10 to 30 μm. If the barrier layer 1c is too thin, the oxygen permeability of the base material layer 1 may not be sufficiently low. If the barrier layer 1c is too thick, the followability to the convex portion 5 of the base material layer 1 may deteriorate. Specifically, this thickness is, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 μm, and may also be within the range between any two of the values exemplified here.

[0056] 2. Adhesive layer 2 The adhesive layer 2 is a layer for attaching the adhesive sheet 10 to the semiconductor wafer 4 and is formed of an adhesive. The shape of the adhesive layer 2 has an opening 2a with a diameter smaller than that of the semiconductor wafer 4. That is, the adhesive layer 2 is annular. The opening 2a is a portion where no adhesive is provided and has a diameter smaller than that of the semiconductor wafer 4. The diameter of the opening 2a / the diameter of the semiconductor wafer 4 is preferably 0.950 to 0.995, and more preferably 0.960 to 0.990.

[0057] The outer peripheral portion 4a of the semiconductor wafer 4 is attached to the adhesive layer 2 so that the convex portion 5 of the semiconductor wafer 4 is disposed within the opening 2a. Therefore, since the convex portion 5 does not come into contact with the adhesive, adhesive residue on the convex portion 5 is prevented.

[0058] The width of the adhesive layer 2 is preferably 10 to 100 mm, and more preferably 30 to 70 mm. The thickness of the adhesive layer 2 is preferably 1 to 100 μm, and more preferably 5 to 50 μm. Specifically, this thickness is, for example, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 100 μm, and may also be within the range between any two of the values exemplified here.

[0059] The adhesive layer 2 is preferably formed of an acrylic resin composition containing an acrylic resin. The acrylic resin of the adhesive layer 2 may have the same or different composition from the acrylic resin of the surface treatment layer 1b.

[0060] The proportion of the (meth)acrylic monomer units contained in the acrylic resin constituting the adhesive layer 2 is, for example, 50 to 100% by mass, specifically, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100% by mass, and may be within the range between any two of the numerical values exemplified here.

[0061] Examples of the (meth)acrylic monomer include (meth)acrylic monomers such as butyl (meth)acrylate, 2-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, dimethylacrylamide, diethylacrylamide, acryloylmorpholine, isobornyl acrylate, etc., and functional group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate having a hydroxyl group, (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, acrylamide N-glycolic acid, and cinnamic acid having a carboxyl group, allyl glycidyl ether having an epoxy group, and glycidyl (meth)acrylate.

[0062] It is preferable to blend a crosslinking agent into the acrylic resin composition constituting the adhesive layer 2. Examples of the crosslinking agent include polyfunctional isocyanate crosslinking agents and polyfunctional epoxy crosslinking agents. When the crosslinking agent reacts with a functional group, it forms a crosslinked structure based on the functional group, thereby increasing the cohesive force of the adhesive and suppressing adhesive residue. Furthermore, (meth)acrylates obtained by (meth)acryloylating one or more oligomers / polymers such as 1,2-polybutadiene terminal urethane (meth)acrylate, the hydrogenated product, 1,4-polybutadiene terminal urethane (meth)acrylate, polyisoprene terminal (meth)acrylate, polyester-based urethane (meth)acrylate, polyether-based urethane (meth)acrylate, polyester (meth)acrylate, and bis-A type epoxy (meth)acrylate may be used at the terminal or side chain.

[0063] The blending amount of the crosslinking agent with respect to 100 parts by mass of the acrylic resin is, for example, 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass, and more preferably 1 to 6 parts by mass. Specifically, this blending amount is, for example, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0 parts by mass, and it may also be within the range between any two of the values exemplified here.

[0064] The acrylic resin preferably has a glass transition temperature (Tg) of -30 to 5°C after crosslinking, and more preferably -25 to -5°C. Specifically, this Tg is, for example, -30, -25, -20, -15, -10, -5, 0, 5°C, and it may also be within the range between any two of the values exemplified here.

[0065] The adhesive layer 2 can be formed, for example, by applying an adhesive onto the base material layer 1 or applying it onto a release film and transferring it to the base material layer 1 by a coating method such as general comma coating, gravure coating, roll coating, or screen coating.

[0066] The semiconductor wafer laminated with the adhesive layer 2 is heated in an atmosphere of 100°C for 1 minute, and after cooling to room temperature, the adhesive force measured according to JIS Z0237 at 23°C between the adhesive layer 2 and the semiconductor wafer is preferably 6 to 50 N / 200 mm, more preferably 10 to 30 N / 200 mm. Further, the adhesive force under the above measurement conditions before heating is preferably 6 N / 200 mm or more, for example, 6 to 50 N / 200 mm. These adhesive forces are specifically, for example, 6, 10, 15, 20, 25, 30, 35, 40, 45, 50 N / 200 mm, and may be within the range between any two of the numerical values exemplified herein.

[0067] <Semiconductor wafer 4> The semiconductor wafer 4 has a convex portion 5. The convex portion 5 is an arbitrary structure protruding in the out-of-plane direction of the semiconductor wafer 4. Examples of the convex portion 5 include a protruding electrode and a convex portion of a circuit having unevenness.

[0068] Examples of the semiconductor wafer 4 include not only silicon wafers but also germanium wafers, gallium-arsenic wafers, gallium-phosphorus wafers, gallium-arsenic-aluminum wafers, etc. The diameter of the semiconductor wafer 4 is preferably 1 to 16 inches, more preferably 4 to 12 inches. The thickness of the semiconductor wafer 4 is not particularly limited, but is preferably 500 to 800 μm, more preferably 520 to 775 μm.

[0069] The height of the convex portion 5 is preferably 10 to 500 μm, more preferably 100 to 300 μm. This height is specifically, for example, 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500 μm, and may be within the range between any two of the numerical values exemplified herein.

[0070] The semiconductor wafer 4 preferably has an outer peripheral portion 4a where the convex portion 5 is not provided. The width of the outer peripheral portion 4a is preferably 1.0 to 3.0 mm, more preferably 1.5 to 2.5 mm.

[0071] Examples of final products using the semiconductor wafer 4 having the convex portions 5 include electronic components for logic, memory, sensors, power supplies, and the like.

[0072] <Curable resin 8> The curable resin 8 is a resin that cures by stimulation such as energy rays (e.g., ultraviolet rays) or heat. The curable resin 8 is disposed between the base material layer 1 and the support film 7.

[0073] The curable resin 8 preferably has a viscosity before curing of 100 to 3000 mPa·s, more preferably 200 to 1000 mPa·s. When the viscosity is 100 mPa·s or more, the curable resin 8 becomes point contact rather than surface contact, and the inclusion of air bubbles in the pressing process is suppressed, and the grindability is excellent. When the viscosity is 3000 mPa·s or less, the curable resin 8 is less likely to entrap air bubbles when flowing between adjacent convex portions 5, so the grindability is excellent. The viscosity is measured using an E-type viscometer under the conditions of 23°C and 50 rpm.

[0074] The curable resin 8 preferably has a Shore D hardness after curing of 5 to 70, more preferably 10 to 60. When the Shore D hardness is 5 or more, the holding property of the convex portion 5 is high, so the grindability is excellent. When the Shore D hardness is 70 or less, the adhesive sheet 10 is easily curved when peeled from the semiconductor wafer 4. The Shore D hardness is measured under the conditions conforming to JIS K 6253.

[0075] The curable resin 8 is preferably a photocurable resin, more preferably an ultraviolet curable resin.

[0076] The curable resin 8 is preferably based on an acrylic resin, and its composition is not particularly limited, but a curable resin containing 1,2-hydrogenated polybutadiene terminal urethane (meth)acrylate, isobornyl acrylate, and diethylacrylamide is preferable because it can improve the adhesiveness between the base material layer 1 and the support film 7.

[0077] The curing shrinkage rate of the curable resin 8 is preferably 7% or less.

[0078] When the height of the convex portion 5 is Td (μm), the thickness of the curable resin 8 is preferably (Td + 20) to (Td + 200) μm, and more preferably (Td + 50) to (Td + 150) μm.

[0079] <Support film 7> The support film 7 is any film capable of supporting the curable resin 8, and can be formed of polyolefins such as ethylene vinyl acetate, polyethylene, polypropylene, polybutene, polybutadiene, etc., as well as polyvinyl chloride, polyethylene terephthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyimide, etc.

[0080] The thickness of the support film 7 is preferably 10 to 300 μm, and more preferably 30 to 250 μm.

[0081] 2. Method for manufacturing a semiconductor wafer Using FIGS. 1 to 9, a method for manufacturing a semiconductor wafer using the adhesive sheet 10 will be described. This manufacturing method includes a frame attaching step, a heating step, a cutting step, a resin curing step, a grinding step, and a peeling step. The order of performing these steps is not limited to this order, and the order can be appropriately changed. Hereinafter, each step will be described.

[0082] <Frame attaching step> As shown in FIGS. 1 to 2, in the frame attaching step, the adhesive sheet 10 is attached to the ring frame 3. The ring frame 3 has an opening 3a having a diameter larger than that of the opening 2a of the adhesive layer 2, and the ring frame 3 can be attached to the adhesive layer 2. Thereby, the adhesive sheet 10 is stably held on the ring frame 3, and the handling of the adhesive sheet 10 becomes easy.

[0083] <Wafer attaching step · Heating step> As shown in FIGS. 2 to 3, in the wafer bonding process, the adhesive sheet 10 is bonded to the outer peripheral portion 4a of the semiconductor wafer 4 under reduced pressure on the surface of the semiconductor wafer 4 where the convex portions 5 are provided. The width of the bonding surface where the semiconductor wafer 4 is bonded to the adhesive layer 2 is preferably 1.0 to 3.0 mm, more preferably 1.5 to 2.5 mm.

[0084] This process can be performed by bonding the semiconductor wafer 4 to the adhesive sheet 10 in the decompression chamber 16. The pressure in the decompression chamber 16 only needs to be lower than the atmospheric pressure, preferably 1000 Pa or less, more preferably 500 Pa or less, and even more preferably 100 Pa or less. The lower limit of the pressure in the decompression chamber 16 is not particularly defined, but is, for example, 10 Pa.

[0085] By bonding the semiconductor wafer 4 to the adhesive sheet 10 under reduced pressure in this way, the inside of the sealed space 2b surrounded by the semiconductor wafer 4 and the adhesive sheet 10 is in a reduced pressure state.

[0086] When the adhesive sheet 10 to which the semiconductor wafer 4 is bonded in that state is taken out of the decompression chamber 16 and exposed to the atmospheric pressure, the base material layer 1 is pushed by the atmospheric pressure and tries to enter the sealed space 2b. The base material layer 1 has high rigidity when not heated, and the base material layer 1 hardly enters the sealed space 2b. On the other hand, in the heating process, when the base material layer 1 is heated to 60 to 150 ° C, the base material layer 1 is softened, and as shown in FIG. 4, the base material layer 1 enters the sealed space 2b. For this reason, the convex portions 5 are embedded in the base material layer 1, and the convex portions 5 are protected by the base material layer 1. The ratio of the height of the embedded portion of the convex portion 5 to the total height of the convex portion 5 is preferably 0.2 to 1, more preferably 0.5 to 1, and even more preferably 0.8 to 1. The heating temperature of the base material layer 1 is preferably 80 to 120 ° C. The heating time of the base material layer 1 is preferably 3 to 120 seconds, more preferably 5 to 60 seconds.

[0087] The heating of the base material layer 1 may be performed before or after bonding the semiconductor wafer 4 to the adhesive sheet 10. Further, this heating may be performed inside or outside the decompression chamber 16.

[0088] <Cutting process> As shown in FIGS. 4 to 5, in the cutting process, the adhesive sheet 10 is cut along the outer periphery of the semiconductor wafer 4. As a result, the adhesive sheet 10 to which the semiconductor wafer 4 is attached is separated from the ring frame 3. The cutting process may be performed after the resin curing process.

[0089] <Resin curing process> In the resin curing process, after the wafer attaching process, the base material layer 1 is brought into contact with the curable resin 8, and the curable resin 8 is cured in that state. In one example, this process can be implemented by the following method.

[0090] First, as shown in FIGS. 5 to 6, the curable resin 8 is spread by moving the adhesive sheet 10 in a state where the adhesive sheet 10 faces the curable resin 8 supplied on the support film 7.

[0091] In one example, the semiconductor wafer 4 is adsorbed by the decompression unit 6 having the decompression holes 6a, and in that state, the adhesive sheet 10 is pressed against the curable resin 8. In that state, the curable resin 8 is spread by moving the adhesive sheet 10 along the surface of the support film 7.

[0092] Next, as shown in FIGS. 6 to 7, the curable resin 8 is cured in a state where the base material layer 1 is in contact with the curable resin 8.

[0093] In one example, the curable resin 8 can be cured into the cured resin 18 by irradiating the curable resin 8 with energy rays 9 such as ultraviolet rays through the support film 7. As a result, the adhesive sheet 10 is stably held on the support film 7.

[0094] <Grinding process> As shown in FIGS. 7 to 8, in the grinding process, the back surface 4b of the semiconductor wafer 4 is ground.

[0095] The back surface 4b of the semiconductor wafer 4 is the surface opposite to the surface on which the convex portions 5 are provided. There is no particular limitation on the method of grinding the back surface of the wafer, and a known grinding method is adopted. Grinding is preferably performed while cooling by applying water to the wafer and a grindstone (such as diamond). The thickness of the thinned wafer is preferably 300 μm or less, and more preferably 50 μm or less.

[0096] During back grinding, since a load in the in-plane direction of the semiconductor wafer 4 is applied to the convex portions 5, the convex portions 5 are likely to be damaged. However, in this embodiment, since at least a part of the convex portions 5 is embedded in the base material layer 1 and the cured curable resin 8, the convex portions 5 are stably supported by the base material layer 1 and the cured curable resin 8, so that the convex portions 5 are less likely to be damaged.

[0097] <Peeling step> As shown in FIGS. 8 to 9, in the peeling step, the adhesive sheet 10 is peeled from the semiconductor wafer 4. The peeling of the adhesive sheet 10 can be performed by bending the adhesive sheet 10 in a direction away from the semiconductor wafer 4.

[0098] Thereby, the back grinding step of the semiconductor wafer 4 is completed. When back grinding is performed using an adhesive sheet in a form such that the convex portions 5 are in contact with the adhesive, the adhesive may adhere to the convex portions 5. However, in this embodiment, since the convex portions 5 do not contact the adhesive layer 2, adhesion of the adhesive to the convex portions 5 is suppressed.

[0099] Note that a dicing step may be performed before the peeling step. In the dicing step, the semiconductor wafer 4 is diced to divide the semiconductor wafer 4 into a plurality of semiconductor chips. The dicing method is not particularly limited, and any method such as blade dicing, laser dicing, stealth dicing, or plasma dicing may be used.

[0100] When the dicing step is performed, a plurality of semiconductor chips are in a state of being attached to the adhesive sheet 10. Therefore, the peeling step is a step of peeling each of the plurality of semiconductor chips from the adhesive sheet 10.

[0101] 3. Substrate Sheet As shown in Fig. 10, the substrate sheet 11 of an embodiment of the present invention can have the same configuration as the above-described substrate layer 1. That is, the substrate sheet 11 includes a cushion layer 1a and a barrier layer 1c, and the oxygen permeability measured based on JIS K 71 26 -2 (isobaric method) at 25°C and 0% RH is 1000 ml / (m 2 ·24 h·atm) or less. The substrate sheet 11 may include a surface treatment layer 1b. The descriptions of the substrate layer 1, the cushion layer 1a, the surface treatment layer 1b, and the barrier layer 1c are the same as those in "1-1. Substrate layer 1".

[0102] The substrate sheet 11 can be used as the substrate layer 1 of the adhesive sheet 10 for back grinding of the semiconductor wafer 4 having the convex portions 5. Further, the substrate sheet 11 may be used as a sheet for back grinding of the semiconductor wafer 4 having the convex portions 5 without providing the adhesive layer 2. In this case, for example, after reducing the pressure in the sealed space 2b formed by pressing the substrate sheet 11 against the semiconductor wafer 4 in the decompression chamber 16 shown in the <Wafer attachment step · Heating step> of the above-described "2. Method for manufacturing a semiconductor wafer", the substrate sheet 11 and the semiconductor wafer 4 are taken out from the decompression chamber 16, and the substrate sheet 11 can be adhered to the semiconductor wafer 4 by the action of atmospheric pressure. In addition, in order to form the sealed space 2b, for example, an annular packing having the same shape as the adhesive layer 2 may be disposed between the substrate sheet 11 and the semiconductor wafer 4.

Examples

[0103] 1. Manufacture of the Adhesive Sheet 10 <Example 1> In Example 1, the substrate layer 1 was formed by laminating the barrier layer 1c and the cushion layer 1a, and the adhesive sheet 10 was manufactured by forming an annular adhesive layer 2 having the opening 2a on the cushion layer 1a.

[0104] A more detailed description is as follows.

[0105] · Preparation of cushion layer 1a First, a cushion layer 1a composed of a metal ion cross-linked product of an ethylene-methacrylic acid copolymer with a thickness of 150 μm (Funclare HMD manufactured by Gunze Co., Ltd.) was prepared. The ethylene-methacrylic acid copolymer had a methacrylic acid unit ratio of 15% by mass, an MFR (JIS K7210, 125 °C / 10.0 kg load) of 5 g / 10 min, and a melting point (JIS K7121) of 72 °C.

[0106] · Formation of base material layer 1 First, an acrylic copolymer composed of 70 parts by mass of butyl acrylate, 22 parts by mass of methyl methacrylate, 5 parts by mass of 2-hydroxyethyl methacrylate, and 3 parts of glycidyl methacrylate monomer as constituent monomers was polymerized. To 100 parts by mass of this acrylic copolymer, 4 parts by mass of an isocyanate cross-linking agent (Nippon Polyurethane Industry Co., Ltd.: Coronate L-45E) was added to prepare an adhesive.

[0107] Next, the above adhesive was coated on a barrier layer 1c composed of a 25-μm-thick PET film (Toray Industries, Inc. Lumirror S10) and dried at 100 °C for 1 minute to form an adhesive layer with a thickness of 10 μm.

[0108] Next, the cushion layer 1a was laminated on the adhesive layer and aged in an atmosphere at 40 °C for 72 hours to form the base material layer 1.

[0109] · Formation of adhesive layer 2 54.4 parts by mass of hydrogenated polybutadiene diacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name BAC-45), 13.6 parts by mass of isodecyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name IDAA), 32 parts by mass of isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name IBXA), 7 parts by mass of α-aminoalkylphenone (manufactured by BASF, trade name Omnirad 379EG) as a photopolymerization initiator, 3 parts by mass of vinyl ether polymer (manufactured by Kyoeisha Chemical Co., Ltd., Floren AC-903) as an antifoaming agent, and 3 parts by mass of isocyanate (manufactured by Asahi Kasei Corporation, trade name "TPA-100") as a crosslinking agent were added to prepare a liquid composition. This composition was screen-printed onto the substrate layer 1 in a specific shape, and after UV irradiation, aging at 40 °C for 4 days was carried out to form an annular adhesive layer 2 with a thickness of 10 μm.

[0110] <Example 2> An adhesive sheet 10 was produced in the same manner as in Example 1, except that a PA film (Toyobo Harden N1202) with a thickness of 15 μm was used as the barrier layer 1c.

[0111] <Example 3> An adhesive sheet 10 was produced in the same manner as in Example 1, except that a PI film (Toray-Dupont Kapton EN) with a thickness of 12 μm was used as the barrier layer 1c.

[0112] <Comparative Example 1> An adhesive sheet 10 was produced in the same manner as in Example 1, except that the cushion layer 1a was used as the substrate layer 1 directly without forming the barrier layer 1c.

[0113] <Comparative Example 2> An adhesive sheet 10 was produced in the same manner as in Example 1, except that a PC film (International Chemical Lacron AA) with a thickness of 30 μm was used as the barrier layer 1c.

[0114] 2. Back grinding of semiconductor wafer Using the above-prepared adhesive sheet 10, the back surface of the semiconductor wafer 4 was ground by the following method.

[0115] <Frame attachment step> First, the adhesive sheet 10 was attached to the ring frame 3.

[0116] <Wafer Attachment Process and Heating Process> Next, the adhesive sheet 10 was attached to the outer peripheral portion 4a of the semiconductor wafer 4 in the reduced-pressure chamber 16 on the surface of the semiconductor wafer 4 where the convex portions 5 were provided. As the semiconductor wafer 4, one having a diameter of 8 inches, a thickness of 725 μm, and bumps (protruding electrodes) with a height of 90 μm formed in a region other than 3.0 mm from the outer periphery was used. The width of the attachment surface where the semiconductor wafer 4 was adhered to the adhesive layer 2 was 2.0 mm. The pressure in the reduced-pressure chamber 16 was 100 Pa. In the reduced-pressure chamber 16, the base material layer 1 was heated to 100°C.

[0117] Next, the adhesive sheet 10 to which the semiconductor wafer 4 was attached was taken out from the reduced-pressure chamber 16.

[0118] <Cutting Process> Next, the adhesive sheet 10 was cut along the outer periphery of the semiconductor wafer 4 to separate the ring frame 3 from the adhesive sheet 10.

[0119] <Resin Curing Process> Next, with the adhesive sheet 10 facing the curable resin 8 supplied onto the support film 7, the curable resin 8 was spread by moving the adhesive sheet 10 in the in-plane direction of the support film 7. As the curable resin 8, one composed of 1,2-hydrogenated polybutadiene terminal urethane (meth)acrylate, isobornyl acrylate, and diethylacrylamide was used. The viscosity of the curable resin 8 before curing (measured using an E-type viscometer under the conditions of 23°C and 50 rpm) was 470 mPa·s.

[0120] Next, with the base material layer 1 in contact with the curable resin 8, the curable resin 8 was cured to obtain a cured resin 18. The curable resin 8 was irradiated with ultraviolet light so that the integrated light quantity at a wavelength of 365 nm with respect to the curable resin from the support film 7 side became 2000 mJ / cm 2 and cured. The Shore D hardness (JIS K 6253) of the cured resin 18 was 15.

[0121] <Grinding Process> Next, the back surface of the semiconductor wafer 4 was ground until the thickness of the semiconductor wafer 4 reached 100 μm. The back surface grinding was performed using a grinding machine (Back Grinder DFG-841 manufactured by DISCO Corporation).

[0122] <Dicing Process> Next, the semiconductor wafer 4 after back surface grinding was diced to divide it into semiconductor chips of 0.49 mm × 0.3 mm.

[0123] Dicing was performed by rotating a dicing blade containing diamond abrasive grains at high speed using a dicing apparatus. The main settings for dicing are as follows. Dicing apparatus: DAD341 manufactured by DISCO Dicing blade: NBC-ZH205O-27HEEE manufactured by DISCO Dicing blade rotation speed: 40,000 rpm Dicing blade feed rate: 50 mm / second Cutting water temperature: 25°C Cutting water volume: 1.0 liter / minute

[0124] <Peeling Process> Next, the semiconductor chips were peeled from the adhesive sheet 10.

[0125] 3. Evaluation Each evaluation was performed on the manufactured adhesive sheet 10. The results are shown in Table 1.

[0126] As shown in Table 1, in all the examples, good results were obtained in all the evaluation items. In Comparative Examples 1 and 2 where the oxygen permeability of the base material layer 1 was high, the bump followability and chip contamination resistance were insufficient.

[0127]

Table 1

[0128] The details of the evaluation method are as follows. <Bump followability> The bump followability was evaluated by the method shown below.

[0129] For the adhesive sheet 10 to which the semiconductor wafer 4 was attached after performing the cutting process of the above-mentioned "2. Back grinding of the semiconductor wafer", the distance that the base material layer 1 followed between the bumps was measured, and the followability (= the distance that the base material layer 1 followed between the bumps / the height of the bumps) was calculated.

[0130] The bump followability was evaluated from the followability according to the following criteria. 〇 (Excellent): Followability of 95% or more △ (Good): Followability of 71 - 94% × (Poor): Followability of less than 70%

[0131] <Chip contamination resistance> The chip contamination resistance was evaluated by observing the chip surface (the surface with bumps) of the semiconductor chip after the peeling process of the above-mentioned "2. Back grinding of the semiconductor wafer" with an optical microscope, and based on whether there is contamination on the chip surface by water or gas, according to the following criteria. 〇 (Excellent): No contamination × (Poor): Contamination exists

[0132] <Adhesion between the base material layer and the wafer> The adhesion between the base material layer and the wafer was measured by the following method. A test piece with a width of 10 mm and a length of 100 mm was cut out from a part near the center of the adhesive sheet 10 where the adhesive layer 2 was not formed (that is, the part where the base material layer was exposed), and using this test piece, it was measured in accordance with the adhesion measurement method of JIS Z0237 (2009) (Method 1: The test method of peeling the tape and sheet at 180° from the stainless steel test plate). Specifically, after the test piece was pressure-bonded to the adherend (Si wafer) with a cleaned surface using a pressure-bonding device (roller weight 2 kg), it was heated on a hot plate at 100 °C for 1 min. The adhesion when the test piece was peeled off from the adherend at 180° was measured with a universal tensile testing machine (Tensilon, model number: RTG-1210, manufactured by ORIENTEC) under the following conditions in an environment of temperature 23 °C and humidity 50%, and the measurement results were converted to values in a width of 200 mm. Measurement mode: Tension Tensile speed: 300 mm / min Distance between chucks: 50 mm Measured sample width: 10 mm

[0133] <Oxygen permeability> The oxygen permeability of the base material layer 1 at 25 °C RH 0% (DRY) was measured using an oxygen permeability measuring device (GTR-10XFKS, manufactured by GTR Tech) by a gas chromatograph method according to JIS K 7126-2 (isobaric method).

Explanation of symbols

[0134] 1: Base material layer, 1a: Cushion layer, 1b: Surface treatment layer, 1c: Barrier layer, 2: Adhesive layer, 2a: Opening, 2b: Sealed space, 3: Ring frame, 3a: Opening, 4: Semiconductor wafer, 4a: Outer peripheral part, 4b: Back surface, 5: Protrusion, 6: Vacuum unit, 6a: Vacuum hole, 7: Support film, 8: Curable resin, 9: Energy ray, 10: Adhesive sheet, 11: Base material sheet, 16: Vacuum chamber, 18: Cured resin

Claims

1. An adhesive sheet for back grinding of a semiconductor wafer having a convex portion, comprising: a base material layer and an adhesive layer provided on the base material layer, the adhesive layer has an opening smaller in diameter than the diameter of the semiconductor wafer, and is attached to the outer peripheral portion of the semiconductor wafer such that the convex portion of the semiconductor wafer is disposed within the opening, configured such that the convex portion is protected by the base material layer in a state where the semiconductor wafer is attached to the adhesive layer, the base material layer includes a cushion layer and a barrier layer, the cushion layer is composed of a thermoplastic resin having a softening temperature measured based on JIS K7206 of 45 to 200 °C and a melting point measured based on JIS K7121 of 60 to 200 °C, The base material layer has an oxygen permeability of 1000 ml / (m ２ ·24 h·atm) or less as measured based on JIS K 7126-2 (isobaric method) at 25°C and 0% RH, and is an adhesive sheet.

2. The adhesive sheet according to claim 1, wherein the barrier layer is provided on the side opposite to the adhesive layer when viewed from the cushion layer.

3. The adhesive sheet according to claim 1 or claim 2, wherein the convex portion is protected by being embedded in the base material layer.

4. The adhesive sheet according to claim 1 or claim 2, wherein the semiconductor wafer is attached to the adhesive layer under reduced pressure.

5. A method for manufacturing a semiconductor wafer using the adhesive sheet according to claim 1 or claim 2, comprising: a frame attaching step, a wafer attaching step, a heating step, a cutting step, a resin curing step, and a grinding step, in the frame attaching step, the adhesive sheet is attached to a ring frame, in the wafer attaching step, the adhesive sheet is attached to the outer peripheral portion of the semiconductor wafer under reduced pressure on the surface of the semiconductor wafer where the convex portion is provided, in the heating step, the base material layer is heated, in the cutting step, the adhesive sheet is cut along the outer periphery of the semiconductor wafer, in the resin curing step, after the wafer attaching step, the base material layer is brought into contact with a curable resin, and the curable resin is cured in that state, in the grinding step, the back surface of the semiconductor wafer is ground.

6. A base sheet, comprising: a cushion layer and a barrier layer, the cushion layer is composed of a thermoplastic resin having a softening temperature measured based on JIS K7206 of 45 to 200 °C and a melting point measured based on JIS K7121 of 60 to 200 °C. A base sheet having an oxygen permeability of 1000 ml / (m ２ ·24 h·atm) or less as measured based on JIS K 7126-2 (isobaric method) at 25°C and 0% RH.

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