Wafer processing tape and wafer processing method

Abstract

The invention relates to a belt for wafer processing and a wafer processing method. The purpose of the present invention is to provide a wafer processing tape that does not easily cause edge breakage, and a wafer processing method using the wafer processing tape. The wafer processing tape has a following layer and a back surface layer disposed on the back surface of the following layer, a test piece of 297 mm * 210 mm is cut, and the average value of the warpage amounts of four corners from a stage is 30 mm or less in a state in which the back surface layer is positioned below and placed on a flat stage.

Description

Technical Field

[0001] The present invention relates to a wafer processing belt and a wafer processing method. Background Art

[0002] When processing semiconductor wafers, adhesive sheets are applied to protect them from damage. For example, during the backgrinding process, adhesive sheets are applied to protect the patterned surface of the semiconductor wafer. To ensure adhesion to uneven patterned surfaces such as protruding electrodes (bumps) and to ensure reliable protection of the patterned surface, adhesive sheets are required to conform to the unevenness of the patterned surface (high-low contrast tracking).

[0003] In order to make the adhesive sheet more conformable, the common method on the market is to increase the thickness of the adhesive and provide a soft resin layer with cushioning properties between the base film and the adhesive. However, if the pattern surface has large unevenness, the conformability is insufficient and the risk of adhesive residue increases.

[0004] Furthermore, for the purpose of improving the adhesion between the substrate and the stage during semiconductor wafer processing, a substrate for an adhesive sheet for semiconductor wafer processing is known that has a heat shrinkage rate of 0% or more in both MD and TD after heating at 130°C for 10 minutes (Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: WO2023 / 068088 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] However, conventional substrates have a problem in that chips are easily broken (hereinafter also referred to as "chipping") when dicing a wafer with a rotary blade. If chipping occurs, the bending strength of the semiconductor chip decreases, and the yield rate also decreases.

[0010] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a wafer processing tape that is less likely to cause edge chipping and a wafer processing method using the wafer processing tape.

[0011] Means for solving problems

[0012] The inventors of the present invention have conducted intensive research to solve the above-mentioned problems and have found that providing a back surface layer on the opposite side of the surface in contact with the wafer, that is, on the back surface of the following layer, can solve the above-mentioned problems, thereby completing the present invention.

[0013] That is, the present invention is as follows.

[0014] [1]

[0015] A wafer processing tape comprising a following layer and a back layer disposed on the back side of the following layer.

[0016] A test piece of 297 mm x 210 mm was cut out and placed on a flat stage with the back surface layer facing downward. The average warpage of the four corners from the stage was 30 mm or less.

[0017] [2]

[0018] The wafer processing tape according to [1] further comprises a release layer disposed on the surface of the following layer.

[0019] 〔3〕

[0020] The wafer processing tape according to [1] or [2] further comprises an adhesive layer between the following layer and the back surface layer.

[0021] [4]

[0022] The wafer processing tape according to any one of [1] to [3], wherein the back surface layer has a thickness of 3 to 50 μm.

[0023] 〔5〕

[0024] The wafer processing tape according to any one of [1] to [4], wherein the back surface layer has a tensile elastic modulus of 2.0 to 5.0 GPa.

[0025] [6]

[0026] The wafer processing tape according to any one of [1] to [5], wherein the back surface layer has a heat shrinkage rate of 3.0% or less at 150° C. for 30 minutes.

[0027] [7]

[0028] The wafer processing tape according to any one of [1] to [6], wherein the following layer has a thickness of 50 to 500 μm.

[0029] 〔8〕

[0030] The wafer processing tape according to [2], wherein the release layer has a thickness of 0.5 to 10 μm.

[0031] 〔9〕

[0032] A wafer processing method comprising:

[0033] a laminating step of laminating the wafer processing tape described in any one of [1] to [8] to the element forming surface of the wafer; and

[0034] The dicing step dices the wafer bonded to the wafer processing tape.

[0035]

[10]

[0036] The wafer processing method as described in [9] further includes a back grinding step of grinding the non-element forming surface of the wafer.

[0037]

[11]

[0038] The wafer processing method described in [9] or

[10] further comprises a peeling step of peeling off the wafer processing tape after the back surface grinding step.

[0039] Effects of the Invention

[0040] According to the present invention, a wafer processing tape and a wafer processing method in which edge chipping is unlikely to occur can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] [ Figure 1 ] is a schematic cross-sectional view showing the wafer processing belt of this embodiment.

[0042] [ Figure 2 ] is a flow chart showing the chip processing method of this embodiment.

[0043] Description of Reference Numerals

[0044] 10…wafer processing tape, 11…release layer, 11a…surface, 12…following layer, 12a…surface, 13…adhesive layer, back layer, 20…wafer, 20a…element forming surface, 20b…non-element forming surface, 22…convex portion, 30…semiconductor chip, S1…bonding step, S2…back grinding step, S3…dicing step, S4…peeling step. DETAILED DESCRIPTION

[0045] Hereinafter, an embodiment of the present invention (hereinafter referred to as “this embodiment”) will be described in detail, but the present invention is not limited thereto and various modifications are possible without departing from the gist of the invention.

[0046] 1. Wafer processing tape

[0047] The wafer processing tape of this embodiment has a following layer and a back layer arranged on the back side of the following layer. A 297mm×210mm test piece is cut out, and when the back layer is placed at the bottom and the tape is placed on a flat platform, the average warping amount of the four corners from the platform is less than 30mm.

[0048] Figure 1 A schematic cross-sectional view of the wafer processing tape of this embodiment is shown in FIG. Figure 1As shown, the wafer processing tape 10 of this embodiment includes a following layer 12 and a back layer 14 disposed on the back surface 12b side of the following layer 12. The following layer 12 and the back layer 14 may be directly laminated, or an adhesive layer 13 may be interposed between the following layer 12 and the back layer 14, and the back layer 14 may be bonded to the following layer 12 via the adhesive layer 13.

[0049] In addition, the wafer processing tape of this embodiment may also have a release layer 11 on the surface 12a of the following layer 12 opposite to the back surface 12b on which the back surface layer 14 is laminated, as needed. Figure 2 As shown, the surface 11a (exposed surface) of the release layer 11 is in close contact with the semiconductor element forming surface 20a of the wafer 20, thereby protecting the semiconductor element forming surface 20a of the wafer 20. Alternatively, in the absence of the release layer 11, the surface 12a of the following layer 12 may also serve as the exposed surface in contact with the semiconductor element forming surface 20a. It should be noted that in this embodiment, in the wafer processing tape and its various layers, the surface in contact with the wafer is referred to as the front surface, and the surface on the opposite side is referred to as the back surface.

[0050] Furthermore, the wafer processing tape 10 of this embodiment preferably does not have an adhesive layer on the surface of the release layer 11. This prevents tape residue from the adhesive layer from contaminating the main surface of the wafer. Furthermore, semiconductor devices can be formed across the entire wafer surface, extending to near the wafer edge, without concern for contamination from tape residue, thereby increasing production yields.

[0051] The warping of the wafer processing tape is 30 mm or less, preferably 25 mm or less, 20 mm or less, 15 mm or less, 10 mm or less, or 5 mm or less. The lower limit of the warping is not particularly limited, but is preferably 0 mm, but may be 1 mm or more. By setting the warping to 30 mm or less, the wafer processing tape and the semiconductor element are less likely to interfere with each other, and adjacent semiconductor elements are less likely to come into contact with each other during peeling due to the warping of the wafer processing tape, thereby further suppressing semiconductor element fragmentation (hereinafter also referred to as "chipping").

[0052] The warpage of this embodiment can be calculated by cutting a 297 mm x 210 mm test piece and placing it on a flat platform with the back layer facing downward. The warpage is then averaged from the platform at the four corners. This warpage can be adjusted by adjusting the thickness and composition of the following layer and back layer, as well as the presence, thickness, and composition of the release layer.

[0053] 1.1. Back layer

[0054] The back layer 14 is positioned on the back side 12b of the following layer 12, imparting rigidity to the relatively flexible following layer 12, which has conformability. This provides support from the back side of the following layer 12, reducing warping and preventing edge chipping. Furthermore, during the process of peeling the wafer 20 or semiconductor chip 30 from the wafer processing tape, the back layer 14 imparts rigidity to the following layer 12 and the release layer 11, providing backside support and preventing the following layer 12 and the release layer 11 from following the wafer 20 or semiconductor chip 30 being peeled. This further enhances the release properties of the following layer 12 and the release layer 11.

[0055] Examples of the back surface layer include polyester films such as polyethylene terephthalate, polyimide films, and polyamide films such as nylon.

[0056] The thickness of the back layer is preferably 3 to 50 μm, 4 to 40 μm, 5 to 30 μm, 6 to 25 μm, 7 to 20 μm, or 8 to 15 μm. When the thickness of the back layer is 3 μm or greater, the amount of concave lateral warping of the surface 12a of the following layer is further reduced, and edge chipping tends to be suppressed. Furthermore, when the thickness of the back layer is 50 μm or less, the amount of convex lateral warping of the surface 12a of the following layer is further reduced, and edge chipping tends to be suppressed.

[0057] The tensile modulus of the back layer is preferably 2.0 to 5.0 GPa, 2.5 to 4.5 GPa, or 3.0 to 4.0 GPa. By adjusting the tensile modulus of the back layer within this range, the rigidity is further improved, and the following layer 12 is supported by the back side, which tends to reduce warping and suppress edge chipping. The tensile modulus can be measured according to JIS K 7127. Furthermore, the tensile modulus can be adjusted by adjusting the material of the back layer.

[0058] The heat shrinkage rate of the back layer at 150°C for 30 minutes is preferably 3.0% or less, 2.5% or less, 2.0% or less, or 1.5% or less. The lower limit of the heat shrinkage rate is not particularly limited, and for example, it is preferably 0%, but may also be 0.1% or more. The heat shrinkage rate can be measured according to JIS C 2318. It should be noted that when the heat shrinkage rate differs depending on the measurement direction, it refers to the maximum heat shrinkage rate when measured in any direction. Therefore, when the heat shrinkage rate in the TD direction is 3.5% and the heat shrinkage rate in the MD direction is 0.1%, the above-mentioned shrinkage rates are not met. In addition, the heat shrinkage rate can be adjusted by the material of the back layer, the stretching ratio, etc.

[0059] 1.2. Adhesive layer

[0060] The adhesive layer 13 can bond the following layer 12 to the back layer 14. The adhesive layer can be made of an acrylic adhesive or an epoxy adhesive. As an example, the adhesive layer can contain a base polymer, an epoxy resin, and a curing agent.

[0061] 1.2.1. Base polymer

[0062] The base polymer is a component that constitutes the main component of the adhesive layer. There are no particular restrictions on the base polymer, and examples thereof include (meth)acrylate copolymers. There are no particular restrictions on the shape of the (meth)acrylate copolymer, and examples thereof include linear, branched, or cross-linked shapes. Among them, a cross-linked shape is preferred. By using such a base polymer, the physical properties of the adhesive layer can be adjusted. The base polymer having a cross-linked or branched shape may also be a polymer formed by bonding an epoxy group of a base polymer having a linear or branched shape via a curing agent described later.

[0063] The monomers constituting the (meth)acrylate copolymer are not particularly limited, and examples thereof include alkyl (meth)acrylates having an alkyl group with 1 to 3 carbon atoms, (meth)acrylates having a glycidyl group, (meth)acrylates having a hydroxyl group, and monomers having an aromatic group. Furthermore, the (meth)acrylate copolymer may contain copolymerizable vinyl monomers other than the acrylic monomer.

[0064] The alkyl (meth)acrylate having an alkyl group with 1 to 3 carbon atoms is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate.

[0065] The content of the structural unit derived from an alkyl (meth)acrylate having an alkyl group with 1 to 3 carbon atoms is preferably 75 to 98% by mass, 80 to 97% by mass, 85 to 96% by mass, or 90 to 95% by mass relative to the total amount of the (meth)acrylate copolymer. When the content of the structural unit derived from an alkyl (meth)acrylate having an alkyl group is within the above range, there is a tendency for the adhesiveness to be further improved and the amount of warping to be further reduced.

[0066] The glycidyl group-containing (meth)acrylate is not particularly limited, and examples thereof include glycidyl (meth)acrylate and allyl glycidyl ether. Structural units derived from glycidyl group-containing (meth)acrylates can be used to introduce epoxy groups into a base polymer. The epoxy groups introduced into the base polymer react with a curing agent (described below), thereby bonding the base polymers to each other and forming three-dimensional crosslinks.

[0067] The content of the structural unit derived from the glycidyl group-containing (meth)acrylate is preferably 0.5-9.0 mass%, 1.0-7.0 mass%, or 2.0-6.0 mass% relative to the total amount of the (meth)acrylate copolymer. By adjusting the content of the structural unit derived from the glycidyl group-containing (meth)acrylate within the above range, the crosslinking density of the base polymer is controlled, the adhesiveness tends to be further improved, and the amount of warping tends to be further reduced.

[0068] The (meth)acrylate having a hydroxyl group is not particularly limited, and examples thereof include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, pentaerythritol triacrylate, glycidyl di(meth)acrylate, and dipentaerythritol pentaacrylate. Structural units derived from a (meth)acrylate having a hydroxyl group can be used to introduce epoxy groups into a base polymer. The hydroxyl groups introduced into the base polymer react with a curing agent described below, thereby bonding the base polymers to each other and forming a three-dimensional crosslink.

[0069] The content of the structural unit derived from the (meth)acrylate having a hydroxyl group is preferably 1.0 to 12.5% ​​by mass, 2.0 to 10% by mass, or 3.0 to 7.0% by mass relative to the total amount of the (meth)acrylate copolymer. By adjusting the content of the structural unit derived from the (meth)acrylate having a hydroxyl group within the above ranges, the crosslinking density of the base polymer is controlled, the adhesiveness tends to be further improved, and the amount of warping tends to be further reduced.

[0070] The monomer having an aromatic group is not particularly limited, and examples thereof include styrene, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate.

[0071] When the structural units of the base polymer have the above-described composition, the adhesiveness tends to be further improved and the amount of warping tends to be further reduced.

[0072] The content of the base polymer is preferably 75-94 mass%, 80-92 mass%, or 82-88 mass% relative to the total amount of the adhesive layer. When the base polymer content is within the above range, the adhesiveness tends to be further improved and the amount of warping tends to be further reduced.

[0073] 1.2.2. Multifunctional Epoxides

[0074] The polyfunctional epoxy compound is not particularly limited, and examples thereof include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol Novolac epoxy resin, cresol Novolac epoxy resin, triphenylmethane epoxy resin, naphthol Novolac epoxy resin, dihydroxybenzene epoxy resin, and tetramethylbiphenol epoxy resin.

[0075] The epoxy equivalent of the polyfunctional epoxy compound is preferably 400 to 700 g / eq, 450 to 650 g / eq, or 500 to 600 g / eq. When the epoxy equivalent is within the above range, the adhesiveness tends to be further improved and the amount of warping tends to be further reduced.

[0076] The content of the polyfunctional epoxy compound is preferably 5 to 20 parts by mass, 7 to 18 parts by mass, or 10 to 15 parts by mass relative to 100 parts by mass of the base polymer.

[0077] 1.2.3. Curing agent

[0078] Examples of curing agents include amine compounds, acid anhydride compounds, amide compounds, and phenol compounds. Examples of such curing agents include, but are not particularly limited to, diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, polyamide resins synthesized from a dimer of linolenic acid and ethylenediamine, phthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol Novolac, modified products thereof, and imidazole-based compounds, such as guanidine derivatives.

[0079] The amine value of the amine compound is preferably 250 to 400 mg / KOH, 275 to 375 mg / KOH, or 300 to 350 mg / KOH. When the amine value of the amine compound is within the above range, the adhesiveness tends to be further improved and the amount of warping tends to be further reduced.

[0080] The content of the curing agent is preferably 1 to 12 parts by mass, 3 to 10 parts by mass, or 5 to 8 parts by mass relative to 100 parts by mass of the base polymer.

[0081] 1.3. Following layer

[0082] The following layer 12 follows the irregularities 22 of the wafer 20, protecting them from damage during wafer processing. It also exhibits high conformability, thereby preventing gaps between the release layer and the semiconductor element forming surface 20a, thereby improving adhesion. On the other hand, due to the high adhesion of the following layer 12, when directly in contact with the wafer 20, there is a tendency for adhesive residue to form. However, the inclusion of the release layer 11, described later, further reduces contamination from residue from the tape.

[0083] The following layer preferably comprises a resin. The resin is not particularly limited, and examples thereof include ionomer resins, polyvinyl chloride, polyethylene terephthalate, ethylene-vinyl acetate copolymers, ethylene-acrylic acid-acrylate films, ethylene-ethyl acrylate copolymers, polyethylene, polypropylene, propylene-based copolymers, and ethylene-acrylic acid copolymers. These resins may be used alone or in combination of two or more. More specifically, the following layer may be a mixture, copolymer, or laminate of one of these resins with another resin.

[0084] Since ionomer resins have a cross-linked structure based on metal ions, they can maintain shape stability even when exposed to temporary or local high temperatures, such as in semiconductor processing.

[0085] The ionomer resin is not particularly limited as long as it is a resin that allows a predetermined polymer to undergo intermolecular bonding with metal ions. Examples thereof include polyolefin ionomers, (meth)acrylic acid ionomers, polystyrene ionomers, and polyester ionomers. These ionomer resins may be used alone or in combination of two or more. Among them, polyolefin ionomers and (meth)acrylic acid ionomers are preferred, and (meth)acrylic acid ionomers are more preferred.

[0086] The polyolefin-based ionomer is not particularly limited, and examples thereof include ethylene-methacrylate copolymers, ethylene-acrylate copolymers, and ethylene-methacrylate-acrylate copolymers.

[0087] The (meth)acrylic acid-based ionomer is not particularly limited, and examples thereof include acrylate-acrylate copolymers, acrylate-methacrylate copolymers, methacrylate-acrylate copolymers, and methacrylate-methacrylate copolymers.

[0088] The polystyrene-based ionomer is not particularly limited, and examples thereof include styrene-styrene sulfonate copolymers, styrene-acrylate copolymers, styrene-methacrylate copolymers, styrene-styrene carboxylate copolymers, and styrene-N-methyl-4-vinylpyridinium copolymers.

[0089] The polyester ionomer is not particularly limited, and examples thereof include sulfoterephthalate-copolymerized polyethylene terephthalate, sulfoisophthalate-copolymerized polyethylene terephthalate, sulfoterephthalic acid-copolymerized polybutylene terephthalate, and sulfoisophthalic acid-copolymerized polybutylene terephthalate.

[0090] The metal ions constituting the salt of the ionomer resin are not particularly limited. Examples include monovalent metal ions such as sodium and lithium ions; divalent metal ions such as zinc, calcium, and magnesium ions; and trivalent metal ions such as aluminum ions, with zinc ions being preferred. The polymer and metal ions in the ionomer resin can be used in any combination based on the ionic functional groups in the polymer and the valence of the metal ions.

[0091] The resin may include an elastomer. As the elastomer, there is no particular limitation, and examples thereof include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, silicone rubber, ethylene-vinyl acetate copolymer, ethylene-(meth) acrylic acid copolymer, ethylene-(meth) acrylate copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resins such as 6-nylon and 6,6-nylon, (meth) acrylic resin, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide-imide resin, fluororesin, and phenoxy resin. These elastomers may be used alone or in combination of two or more.

[0092] The content of the resin is preferably 80 to 100% by mass, 85 to 100% by mass, or 90 to 100% by mass relative to the total amount of the following layer.

[0093] The following layer may contain additives other than the resin, as needed. These additives are not particularly limited, and examples include plasticizers, heat stabilizers, colorants, organic lubricants, inorganic lubricants, surfactants, processing aids, and antistatic agents. These additives may be used alone or in combination of two or more.

[0094] The thickness of the following layer is preferably 50-500 μm, 75-400 μm, 70-300 μm, or 100-250 μm. When the thickness of the following layer is within this range, warping tends to be further reduced and edge chipping is suppressed. Furthermore, when the thickness of the following layer is within this range, conformability to wafer irregularities is further improved, and voids are less likely to enter between the wafer processing tape and the surface on which the semiconductor element is formed, resulting in improved adhesion.

[0095] 1.4. Release layer

[0096] The release layer 11 is a layer laminated on the following layer 12. During the semiconductor processing, the release layer 11 can adhere closely to the wafer 20 to protect the semiconductor element forming surface 20a, and can be peeled off after the process without generating residual adhesive.

[0097] The release layer can contain a base polymer, a monomer, a photopolymerization initiator, and a curing agent. The inclusion of the monomer and photopolymerization initiator allows the wafer processing tape to adhere to the wafer. After the specified semiconductor processing step is performed, the release layer is exposed to light, causing a polymerization reaction to proceed within the release layer, reducing the release layer's adhesion to the semiconductor device formation surface of the wafer. By controlling adhesion in this way, contamination caused by water spread can be suppressed during semiconductor processing steps requiring adhesion, such as the back grinding step S2 and the scribing step S3 described later. Furthermore, by reducing adhesion during the stripping step S4, contamination caused by tape residue can be further suppressed.

[0098] The thickness of the release layer is preferably 0.2 to 15 μm, 0.5 to 10 μm, 0.7 to 7.0 μm, or 1.0 to 5.0 μm. When the release layer thickness is 0.2 μm or greater, the amount of lateral convex warping of the surface 12a of the following layer tends to be further reduced, and edge chipping is suppressed. Furthermore, when the release layer thickness is 0.2 μm or greater, the releasability tends to be further improved. Furthermore, when the release layer thickness is 15 μm or less, the amount of lateral concave warping of the surface 12a of the following layer tends to be further reduced, and edge chipping is suppressed.

[0099] The ratio of the thickness of the back layer to the thickness of the release layer (back layer / release layer) is preferably 1 to 40, 2 to 20, 3 to 15, or 4 to 10. By setting the thickness ratio (back layer / release layer) within the above range, the convex warping on the surface 12a side of the following layer and the concave warping on the surface 12a side of the following layer are balanced, the amount of warping is further reduced, and edge chipping tends to be suppressed.

[0100] 1.4.1. Base polymer

[0101] The base polymer is a component that constitutes the main component of the release layer. There are no particular restrictions on the base polymer, and examples thereof include (meth)acrylate copolymers. There are no particular restrictions on the shape of the (meth)acrylate copolymer, and examples thereof include linear, branched, or cross-linked shapes. Among them, a cross-linked shape is preferred. By using such a base polymer, the physical properties of the release layer can be adjusted. The base polymer having a cross-linked or branched shape can be a polymer formed by bonding an epoxy group of a base polymer having a linear or branched shape via a curing agent described later.

[0102] The monomers constituting the (meth)acrylate copolymer are not particularly limited, and examples thereof include alkyl (meth)acrylates having an alkyl group with 1 to 3 carbon atoms, (meth)acrylates having a glycidyl group, (meth)acrylates having a hydroxyl group, and monomers having an aromatic group. Furthermore, the (meth)acrylate copolymer may contain copolymerizable vinyl monomers other than the acrylic monomer.

[0103] The alkyl (meth)acrylate having an alkyl group with 1 to 3 carbon atoms is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate.

[0104] The content of the structural unit derived from an alkyl (meth)acrylate having an alkyl group with 1 to 3 carbon atoms is preferably 75 to 98% by mass, 80 to 97% by mass, 85 to 96% by mass, or 90 to 95% by mass relative to the total amount of the (meth)acrylate copolymer. By adjusting the content of the structural unit derived from an alkyl (meth)acrylate having an alkyl group within the above range, the dynamic viscoelasticity of the release layer tends to facilitate achieving the above-mentioned physical properties, and contamination due to water seepage and contamination from tape residue tend to be further reduced.

[0105] The glycidyl group-containing (meth)acrylate is not particularly limited, and examples thereof include glycidyl (meth)acrylate and allyl glycidyl ether. Structural units derived from glycidyl group-containing (meth)acrylates can be used to introduce epoxy groups into a base polymer. The epoxy groups introduced into the base polymer react with a curing agent (described below), thereby bonding the base polymers to each other and forming three-dimensional crosslinks.

[0106] The content of the structural unit derived from the glycidyl group-containing (meth)acrylate is preferably 0.5 to 9.0 mass%, 1.0 to 7.0 mass%, or 2.0 to 5.0 mass% relative to the total amount of the (meth)acrylate copolymer. By adjusting the content of the structural unit derived from the glycidyl group-containing (meth)acrylate within the above range, the crosslinking density of the base polymer is controlled, and the dynamic viscoelasticity of the release layer tends to achieve the above-mentioned physical properties.

[0107] The (meth)acrylate having a hydroxyl group is not particularly limited, and examples thereof include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, pentaerythritol triacrylate, glycidyl di(meth)acrylate, and dipentaerythritol pentaacrylate. Structural units derived from a (meth)acrylate having a hydroxyl group can be used to introduce epoxy groups into a base polymer. The hydroxyl groups introduced into the base polymer react with a curing agent described below, thereby bonding the base polymers to each other and forming a three-dimensional crosslink.

[0108] The content of the structural unit derived from the (meth)acrylate having a hydroxyl group is preferably 1.0 to 12.5% ​​by mass, 2.0 to 10% by mass, or 3.0 to 7.0% by mass relative to the total amount of the (meth)acrylate copolymer. By adjusting the content of the structural unit derived from the (meth)acrylate having a hydroxyl group within the above ranges, the crosslinking density of the base polymer is controlled, and the dynamic viscoelasticity of the release layer tends to achieve the above-mentioned physical properties.

[0109] The monomer having an aromatic group is not particularly limited, and examples thereof include styrene, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate.

[0110] The content of the structural unit derived from the monomer having an aromatic group is preferably 0.01 to 1.0 mass %, 0.05 to 0.5 mass %, or 0.1 to 0.3 mass % based on the total amount of the (meth)acrylate copolymer.

[0111] When the structural units of the base polymer have the above-mentioned composition, the dynamic viscoelasticity of the release layer tends to be adjusted to fall within the above-mentioned value range.

[0112] In addition, the weight average molecular weight of the base polymer is preferably 1.0×10 4 ~2.0×10 6 , 5.0×10 4 ~1.5×10 6 , 1.0×10 5 ~1.0×10 6 By setting the weight average molecular weight of the base polymer within the above range, the dynamic viscoelasticity of the release layer can achieve the above physical properties. 4 On the other hand, by setting the weight average molecular weight of the base polymer to 2.0×10 6 As a result, the adhesiveness tends to be further improved, and contamination by water spread tends to be further suppressed.

[0113] The “weight average molecular weight” described in this specification is a molecular weight measured using a gel permeation chromatography analyzer on a sample prepared by dissolving a base polymer in tetrahydrofuran.

[0114] The base polymer preferably has a glass transition temperature of -25 to 15°C, -20 to 10°C, -15 to 5°C, or -10 to 0°C. A base polymer having a glass transition temperature of -25°C or higher tends to further improve releasability and further suppress contamination by tape residue. Furthermore, a base polymer having a glass transition temperature of 15°C or lower tends to further improve adhesion and further suppress contamination by water penetration.

[0115] The base polymer content is preferably 85-98 mass%, 90-97 mass%, or 92-96 mass% relative to the total amount of the release layer. By adjusting the base polymer content within the above range, the dynamic viscoelasticity of the release layer tends to be adjusted within the above range. Furthermore, contamination by residue from the belt and contamination by water seepage tends to be further suppressed.

[0116] 1.4.2. Monomer

[0117] The release layer may contain a polymerizable compound (monomer). As described above, the monomer can be polymerized using a photopolymerization initiator to change the physical properties of the release layer. In addition, the dynamic viscoelasticity of the release layer tends to be adjustable within the above-mentioned range depending on the type and amount of the monomer.

[0118] Such monomers are not particularly limited, and examples thereof include polyfunctional acrylates such as dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, 1,3-butanediol diacrylate, 1,6-hexanediol diacrylate, tricyclodecanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, neopentyl glycol diacrylate, 1,9-nonanediol diacrylate, 2-methyl-1,8-octanediol diacrylate, and 1,10-decanediol diacrylate.

[0119] By using a multifunctional acrylate, the monomer undergoes three-dimensional crosslinking through polymerization, thereby preferentially changing the physical properties of the release layer, and there is a tendency to further suppress contamination by residues from the tape.

[0120] The monomer content is preferably 1 to 12 parts by mass, 1 to 10 parts by mass, or 2 to 8 parts by mass relative to 100 parts by mass of the base polymer. When the monomer content is within the above range, contamination by residue from the belt tends to be further suppressed.

[0121] 1.4.3. Photopolymerization initiator

[0122] The photopolymerization initiator is not particularly limited, and examples thereof include alkylphenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, aromatic ketones, aromatic onium salt compounds, organic peroxides, thio compounds (compounds containing a phenylthio group, etc.), α-aminoalkylphenone compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds. Among them, alkylphenone-based photopolymerization initiators are preferred. These photopolymerization initiators may be used alone or in combination of two or more.

[0123] The content of the photopolymerization initiator is preferably 0.1 to 2.0 parts by mass, 0.2 to 1.5 parts by mass, or 0.3 to 1.0 parts by mass relative to 100 parts by mass of the base polymer. When the content of the photopolymerization initiator is within the above range, contamination tends to be further suppressed.

[0124] 1.4.4. Curing agent

[0125] The curing agent is not particularly limited, and examples thereof include isocyanate compounds, epoxy compounds, and amine compounds. Among them, isocyanate compounds are preferred. The use of such a curing agent tends to crosslink the base polymer and adjust the dynamic viscoelasticity of the release layer to the aforementioned range.

[0126] The isocyanate compound is not particularly limited. Examples thereof include compounds having a group reactive with a hydroxyl group, a carboxyl group, or the like of the base polymer. More specifically, examples include toluene diisocyanates such as trimethylolpropane-added toluene diisocyanate, aromatic diisocyanates such as 4,4-diphenylmethane diisocyanate, and xylylenediisocyanate; alicyclic diisocyanates such as isophorone diisocyanate and methylenebis(4-cyclohexylisocyanate); and aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate. These isocyanate compounds may be used alone or in combination of two or more.

[0127] Among them, the curing agent is preferably a polyfunctional isocyanate compound having two or more functional groups. By using such a curing agent, a plurality of base polymers can also be cross-linked by the curing agent.

[0128] The curing agent content is preferably 0.1 to 7.5 parts by mass, 0.2 to 5.0 parts by mass, or 0.3 to 3.0 parts by mass relative to 100 parts by mass of the base polymer. By adjusting the curing agent content within the above range, the dynamic viscoelasticity of the release layer can be adjusted to the above value range, further suppressing the tendency of contamination by residue from the tape and contamination by water seepage.

[0129] 2. Method for manufacturing wafer processing tape

[0130] The manufacturing method of the wafer processing tape of this embodiment is not particularly limited. For example, as long as there is a process of forming a release layer 11 on the surface 12a of the following layer 12, there is no particular restriction. If necessary, there may also be a process of forming a back layer 14 on the back side 12b of the following layer 12.

[0131] The method for forming the release layer 11 and the back layer 14 is not particularly limited. For example, films may be dry-laminated, or a composition may be applied to the surface of the following layer 12 and dried or photocured to form the release layer 11 and the back layer 14. Alternatively, the release layer 11 and the back layer 14 may be bonded to the following layer 12 via the adhesive layer 13.

[0132] 2. Wafer processing method

[0133] The chip processing method of this embodiment includes: a bonding process of bonding the above-mentioned chip processing tape to the element forming surface of the chip; and a back grinding process of grinding the non-element forming surface of the chip bonded to the chip processing tape. According to needs, it can also include a slicing process of slicing the chip and a peeling process of heating and peeling the chip processing tape.

[0134] Figure 2 FIG. 1 is a flow chart showing a wafer processing method according to the present embodiment by means of a schematic cross-sectional view. Figure 2 In the example shown, a mode is shown in which a release layer is provided in contact with the device forming surface of the wafer. However, when no release layer is provided, the following layer is in contact with the device forming surface of the wafer.

[0135] 2.1. Lamination process

[0136] The bonding step S1 is a step of bonding the wafer processing tape 10 to the element forming surface 20a of the wafer 20. The surface of the wafer 20 to which the wafer processing tape 10 is bonded may be the non-element forming surface 20b.

[0137] In the laminating step, the wafer processing tape 10 may be preheated and laminated to the wafer main surface 20a, or the wafer processing tape 10 may be laminated to the wafer main surface 20a and then heated. By laminating the surface 11a of the release layer 11 to the element forming surface 20a of the wafer in the heated state, the surface 11a of the release layer 11 can follow the element forming surface 20a of the wafer and laminate (see Figure 2 In this manner, by sinking the protrusions 22 into the wafer processing tape 10, the element forming surface 20a of the wafer having the protrusions 22 can be protected.

[0138] The heating temperature is preferably 60 to 150°C, more preferably 70 to 140°C, and even more preferably 80 to 130°C. Furthermore, the heating time for the wafer processing tape 10 is preferably 3 to 120 seconds, more preferably 5 to 90 seconds. By setting the heating conditions within this range, the followability of the wafer processing tape 10 tends to be further improved.

[0139] 2.2. Processing procedures

[0140] The processing steps for processing the wafer 20 while the wafer processing tape 10 and the wafer 20 are bonded together are not particularly limited, and any wafer processing technique can be appropriately applied. For example, the processing steps include back grinding, in which the back surface 20b of the wafer not bonded to the wafer processing tape 10 is ground to obtain a thinned wafer, and dicing, in which the wafer 20 is diced to obtain semiconductor chips.

[0141] In addition, as a processing technology to combine them, such as Figure 2 As shown, a method can be exemplified in which, after the back grinding step S2, a dicing step S3 is performed to diced the thinned wafer by blade dicing, etc. The following describes a process in which the dicing step S3 is performed after the back grinding step S2, but the present embodiment is not limited thereto.

[0142] 2.2.1. Back grinding process

[0143] The back grinding step S2 is a step of grinding the non-element-forming surface 20b of the wafer 20 attached to the wafer processing tape 10. Specifically, from the perspective of protecting the element-forming surface 20a, the non-element-forming surface 20b of the wafer 20 is ground (back grinding) to a desired thickness while the wafer processing tape 10 serving as a back grinding tape is attached to the element-forming surface 20a.

[0144] The specific method for back grinding is not particularly limited, and known methods can be used. For example, a method of grinding while supplying a slurry containing an abrasive to the back surface 20b of the wafer 20 can be used. The thickness of the resulting thinned wafer is not particularly limited as long as it meets the processing objectives. As an example, it is preferably 300 μm or less, 150 μm or less, or 50 μm or less.

[0145] During back grinding, a load is applied in the thickness direction of the wafer 20, which can damage the protrusions 22 and the like, leading to a decrease in yield. In contrast, by using the wafer processing tape 10 of this embodiment, processing can be performed with at least a portion of the protrusions 22 embedded in the wafer processing tape 10, thereby preventing damage to the protrusions 22 and the like.

[0146] In the wafer processing method of this embodiment, when back grinding is performed on a wafer 20 having modified portions and grooves previously formed on its surface for singulation to thin the wafer 20 from its back side 20b, the wafer 20 can be thinned to the same depth as the modified portions and grooves. Thus, thinning by back grinding and singulation can be performed simultaneously.

[0147] 2.2.2. Slicing process

[0148] The dicing step S3 is a step of dicing the wafer 20. The dicing method is not particularly limited, and an example thereof includes blade dicing in which a dicing blade is used to cut the wafer into the semiconductor chips 30.

[0149] 2.3. Peeling process

[0150] The peeling step S4 is a step of peeling the wafer processing tape 10 from the wafer 20 or the semiconductor chip 30. The peeling step of taking out the semiconductor chip 30 from the wafer processing tape is also referred to as a pickup step.

[0151] In the peeling step S4, the wafer processing tape 10 may be peeled at room temperature or under heating. Furthermore, in the peeling step S4, if the release layer 11 contains a monomer and a photopolymerization initiator, the release layer 11 may be cured by irradiation with ultraviolet light before peeling to reduce its adhesion to the wafer 20. This tends to further improve the releasability and further suppress contamination caused by residue from the tape.

[0152] Furthermore, there is no particular limitation on the method for picking up the semiconductor chip 30 from the wafer processing tape. For example, the semiconductor chip 30 may be lifted up by a pin and picked up by suction using a suction collet.

[0153] Furthermore, during pickup, the wafer processing tape 10 may be stretched in the surface direction using an expanding device, and the semiconductor chips 30 may be separated and then picked up by a pickup device.

[0154] Example

[0155] Hereinafter, the present invention will be described in more detail using Examples and Comparative Examples. However, the present invention is not limited to the following Examples.

[0156] [Example 1]

[0157] (Preparation of Release Layer Composition)

[0158] Into a polymerization vessel were placed 62 parts by mass of ethyl acrylate, 30 parts by mass of methyl methacrylate, 5 parts by mass of 2-hydroxyethyl methacrylate, 3 parts by mass of glycidyl methacrylate, 0.2 parts by mass of styrene, and azobisisobutyronitrile as a polymerization initiator, and polymerization was carried out at 60°C for 4 hours. This yielded an acrylic polymer 1 having a glass transition temperature of -5°C and a weight-average molecular weight of 600,000.

[0159] 100 parts by mass of acrylic polymer 1, 4 parts by mass of acrylic monomer 1 (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Light Acrylate DPE-6A", dipentaerythritol hexaacrylate), 0.4 parts by mass of photopolymerization initiator (manufactured by IGM, trade name "Omnirad-184", α-hydroxyalkyl phenone), and 0.5 parts by mass of isocyanate curing agent (manufactured by Mitsui Chemicals, Inc., trade name "Takenate D-101E", toluene diisocyanate) were mixed to prepare a release layer composition.

[0160] (Preparation of Adhesive Layer Composition)

[0161] Into a polymerization vessel were placed 70 parts by mass of butyl acrylate, 22 parts by mass of methyl methacrylate, 5 parts by mass of 2-hydroxyethyl methacrylate, 3 parts by mass of glycidyl methacrylate, and azobisisobutyronitrile as a polymerization initiator, and polymerization was carried out at 60° C. for 4 hours.

[0162] 100 parts by mass of the acrylic polymer 2 and 4 parts by mass of an isocyanate crosslinking agent (CORONATE L-45E manufactured by Nippon Polyurethane Co., Ltd.) were mixed to prepare a composition for an adhesive layer.

[0163] (Formation of Back Layer)

[0164] A polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., model: Toyobo Ester Film E5102, thickness 12 μm, tensile elastic modulus 4.0 GPa, heat shrinkage rate 1.5% when heated at 150°C for 30 minutes) as a back layer and an ionomer film (manufactured by GUNZE Co., Ltd., trade name "FUNCRARE HMD", thickness 150 μm, storage elastic modulus 5.0×10- 6 Pa) The adhesive layer was laminated via the adhesive layer composition, and then heated at a drying temperature of 90° C. under a tension of 120 N to form an adhesive layer.

[0165] (Formation of Release Layer)

[0166] Next, the release layer composition prepared as described above was applied to the surface of the ionomer film opposite to the back layer. Using a UV irradiation device (UVC-4800-4, manufactured by USHIO INC.), high-pressure mercury was used, an illuminance of 160 W, and a cumulative irradiation dose of 1280 mJ. The adhesive layer composition and the release layer composition were irradiated with ultraviolet light to allow a curing reaction to proceed, thereby forming a release layer and an adhesive layer having a thickness of 2 μm. Thus, the wafer processing tape of Example 1 was produced.

[0167] [Example 2]

[0168] A wafer processing tape of Example 2 was produced by the same operation as in Example 1 except that the thickness of the following layer was set to 60 μm.

[0169] [Example 3]

[0170] A wafer processing tape of Example 3 was produced by the same operation as in Example 1 except that the thickness of the following layer was set to 320 μm.

[0171] [Example 4]

[0172] A wafer processing tape of Example 4 was produced by the same operation as in Example 1 except that the thickness of the release layer was set to 0.3 μm.

[0173] [Example 5]

[0174] A wafer processing tape of Example 5 was produced by the same operation as in Example 1 except that the thickness of the release layer was set to 12 μm.

[0175] [Example 6]

[0176] By using a polyethylene terephthalate film (manufactured by Toray Industries, Ltd., model: Lumirror S10, thickness 38 μm, tensile elastic modulus 4.9 GPa) instead of a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., model: Toyobo ester film E5102, thickness 12 μm, tensile elastic modulus 4.0 GPa), the thickness of the back layer was made 38 μm. Except for this, the wafer processing tape of Example 6 was produced by the same operation as Example 1.

[0177] [Comparative Example 1]

[0178] A wafer processing tape of Comparative Example 1 was produced in the same manner as in Example 1 except that the drying temperature during heat curing of the adhesive layer was 120° C. and the tension was 200 N.

[0179] 〔Film warping amount〕

[0180] A 297 mm x 210 mm test piece was cut out from the wafer processing tape obtained as described above, and placed on a flat stage with the back layer facing downward. The warpage from the stage was measured at the four corners, and the average value was determined as the film warpage.

[0181] [Evaluation of chipping resistance]

[0182] Using a tape mounter (DFM-M150, manufactured by DISCO) and an 8-inch ring frame, the wafer processing tape of the embodiment and comparative example was bonded to a Si mirror wafer having a diameter of 5 inches and a thickness of 300 μm. Then, a double-head dicing machine (AW-D-300TX, manufactured by Tokyo Seimitsu) and a blade (ZH05-SD2000-N1-50DC, manufactured by DISCO) were used to dicing under the conditions of a spindle rotation of 20,000 rpm, a dicing speed of 40 mm / sec, and a chip size of 2.2 mm × 2.5 mm. Finally, after peeling the tape, the chip was observed using a digital microscope (VHX-900, manufactured by KEYENCE), and the chips with broken corners were counted as corner crack products. Then, the chipping resistance was evaluated according to the following evaluation criteria.

[0183] (Evaluation Criteria)

[0184] A: The number of semiconductor chips in which corner cracks occurred was 0.

[0185] B: The number of semiconductor chips in which corner cracks occurred was 1 to 10.

[0186] C: The number of semiconductor chips in which corner cracks occurred was 11 to 100.

[0187] D: The number of semiconductor chips in which corner cracks occurred was 101 or more.

[0188] [Table 1]

[0189]

[0190] Industrial applicability

[0191] The wafer processing tape of the present invention has industrial applicability as a tape used in processing processes such as backside grinding and dicing of wafers.

Claims

1. A wafer processing tape comprising a following layer and a back layer disposed on the back side of the following layer. A test piece of 297 mm x 210 mm was cut out and placed on a flat stage with the back surface layer facing downward. The average warpage of the four corners from the stage was 30 mm or less. 2 . The wafer processing tape according to claim 1 , further comprising a release layer disposed on a surface of the following layer. 3 . The wafer processing tape according to claim 1 , further comprising an adhesive layer between the following layer and the back surface layer.

4. The wafer processing tape according to claim 1, wherein The thickness of the back layer is 3 to 50 μm.

5. The wafer processing tape according to claim 1, wherein The tensile elastic modulus of the back layer is 2.0 to 5.0 GPa.

6. The wafer processing tape according to claim 1, wherein The back surface layer has a heat shrinkage of 3.0% or less under the conditions of 150° C. and 30 minutes.

7. The wafer processing tape according to claim 1, wherein The following layer has a thickness of 50 to 500 μm.

8. The wafer processing tape according to claim 2, wherein: The thickness of the release layer is 0.5 to 10 μm.

9. A wafer processing method comprising: a laminating step of laminating the wafer processing tape according to any one of claims 1 to 8 to the element forming surface of the wafer; and The dicing step dices the wafer attached to the wafer processing tape.

10. The wafer processing method according to claim 9, further comprising a back grinding step of grinding a non-element forming surface of the wafer.

11. The wafer processing method according to claim 9, wherein: After the backside grinding step, a peeling step of peeling the wafer processing tape is performed.

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