Tape for wafer processing and wafer processing method

Abstract

To provide a tape for wafer processing which minimizes chipping and to provide a wafer processing method using the tape for wafer processing.SOLUTION: A tape for wafer processing includes a following layer and a backside layer disposed on a rear surface of the following layer. When a test piece measuring 297 mm×210 mm is cut out and placed flat on a stage with the backside layer facing down, the average amount of warpage from the stage of four corners is 30 mm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wafer processing tape and a wafer processing method. [Background technology]

[0002] When semiconductor wafers are processed, adhesive sheets are applied to protect them from damage. For example, in the back grinding process when processing semiconductor wafers, adhesive sheets are applied to protect the patterned surface of the semiconductor wafer. The adhesive sheet is required to have adhesion to patterned surfaces with irregularities such as protruding electrodes (bumps), and to be able to follow the irregularities of the patterned surface (step-following ability) from the standpoint of reliable protection of the patterned surface.

[0003] In order to give adhesive sheets conformability, it is common on the market to increase the thickness of the adhesive or to provide a cushioning, flexible resin layer between the base film and the adhesive, but if the pattern surface is very uneven, there is a higher risk of insufficient conformability or adhesive residue.

[0004] Furthermore, a substrate used in an adhesive sheet for processing semiconductor wafers is known, which has a thermal shrinkage rate of 0% or more in both MD and TD after heating at 130°C for 10 minutes, with the aim of improving the adhesion of the substrate to the stage during the semiconductor wafer processing step (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2023 / 068088 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional substrates have a problem in that chipping occurs easily when the wafer is diced with a rotary blade. Chipping reduces the flexural strength of the semiconductor chip, leading to a decrease in yield.

[0007] The present invention has been made in view of the above problems, and has as its object to provide a wafer processing tape that is less susceptible to chipping, and a wafer processing method using the wafer processing tape. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved by providing a back surface layer on the back surface of the conformal layer, which is the side opposite to the surface that contacts the wafer, and have thus completed the present invention.

[0009] That is, the present invention is as follows. [1] A follow-up layer and a backing layer disposed on the back surface of the follow-up layer, A test piece of 297 mm x 210 mm is cut out and placed on a flat stage with the back surface layer facing downwards. The average amount of warping from the stage at the four corners is 30 mm or less. Tape for wafer processing. [2] Further comprising a release layer disposed on the surface of the follower layer. The wafer processing tape according to [1]. [3] Further, an adhesive layer is provided between the follow-up layer and the back surface layer. The wafer processing tape according to [1] or [2]. [4] The thickness of the back surface layer is 3 to 50 μm. The tape for wafer processing according to any one of [1] to [3]. [5] The back surface layer has a tensile modulus of 2.0 to 5.0 GPa. The tape for wafer processing according to any one of [1] to [4]. [6] The back surface layer has a heat shrinkage rate of 3.0% or less at 150°C for 30 minutes. The tape for wafer processing according to any one of [1] to [5]. [7] The thickness of the follow-up layer is 50 to 500 μm. The tape for wafer processing according to any one of [1] to [6]. [8] The thickness of the release layer is 0.5 to 10 μm. The wafer processing tape according to [2]. [9] a bonding step of bonding the wafer processing tape according to any one of [1] to [8] to the element formation surface of the wafer; a dicing step of dicing the wafer bonded to the wafer processing tape. Wafer processing method.

[10] The method further includes a back-grinding step of polishing a non-element-formed surface of the wafer. The wafer processing method according to [9].

[11] a peeling step of peeling off the wafer processing tape after the back-grinding step; The wafer processing method according to [9] or

[10] . [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a wafer processing tape and a wafer processing method that are less susceptible to chipping. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing a tape for wafer processing according to an embodiment of the present invention. [Figure 2] 3 is a flowchart showing a wafer processing method according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Below, we will explain in detail the embodiment of the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to this and various modifications are possible within the scope of the gist of the present invention.

[0013] 1. Wafer processing tape The wafer processing tape of this embodiment has a follower layer and a back layer disposed on the back side of the follower layer, and when a test piece measuring 297 mm x 210 mm is cut out and placed on a flat stage with the back layer facing downwards, the average amount of warping from the stage at the four corners is 30 mm or less.

[0014] A schematic cross-sectional view of the wafer processing tape of this embodiment is shown in Figure 1. As shown in Figure 1, the wafer processing tape 10 of this embodiment has a following layer 12 and a backing layer 14 disposed on the back surface 12b side of the following layer 12. The following layer 12 and the backing layer 14 may be directly laminated together, or an adhesive layer 13 may be provided between the following layer 12 and the backing layer 14, and the backing layer 14 may be adhered to the following layer 12 via the adhesive layer 13.

[0015] Furthermore, the wafer processing tape of this embodiment may have a release layer 11, if necessary, on the surface 12a of the follower layer 12 opposite to the back surface 12b on which the back surface layer 14 is laminated. As shown in FIG. 2, the surface 11a (exposed surface) of the release layer 11 can protect the semiconductor element forming surface 20a of the wafer 20 by adhering to the semiconductor element forming surface 20a of the wafer 20. Furthermore, if the release layer 11 is not present, the surface 12a of the follower layer 12 may be the exposed surface that contacts the semiconductor element forming surface 20a. In this embodiment, the surface of the wafer processing tape and each layer thereof that contacts the wafer is referred to as the front surface, and the opposite surface is referred to as the back surface.

[0016] 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, it becomes possible to form semiconductor elements all over the wafer, right up to the very edge, without having to worry about contamination from tape residue, thereby increasing yield.

[0017] The amount of warpage 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 amount of warpage is not particularly limited, but is preferably 0 mm, and may be 1 mm or more. By keeping the amount of warpage 30 mm or less, the wafer processing tape and semiconductor elements are less likely to interfere with each other or come into contact with adjacent semiconductor elements during peeling due to warpage of the wafer processing tape, which tends to further suppress chipping of the semiconductor elements (hereinafter also referred to as "chipping").

[0018] In this embodiment, the amount of warpage can be determined by cutting out a test piece of 297 mm × 210 mm, placing the back surface layer face down on a flat stage, and calculating the average amount of warpage from the stage at the four corners. The amount of warpage can be adjusted depending on the thickness and composition of the follow-up layer and back surface layer, and the presence or absence, thickness, and composition of the release layer.

[0019] 1.1.Backing layer The back surface layer 14 is a layer disposed on the back surface 12b side of the conformal layer 12, and provides rigidity from the back surface 12b side to the conformal, relatively soft conformal layer. This provides support to the conformal layer 12, which tends to reduce warpage and suppress chipping. Furthermore, in the peeling process of peeling the wafer 20 or semiconductor chip 30 from the wafer processing tape, the back surface layer 14 provides rigidity to the conformal layer 12 or release layer 11, thereby supporting them from the back, thereby preventing the conformal layer 12 or release layer 11 from following the wafer 20 or semiconductor chip 30 being peeled off. This tends to further improve peelability.

[0020] Examples of the back layer include polyester films such as polyethylene terephthalate, polyimide films, and polyamide films such as nylon.

[0021] The thickness of the back surface 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 surface layer is 3 μm or more, the amount of concave warping on the surface 12a side of the following layer is further reduced, and chipping tends to be suppressed. Furthermore, when the thickness of the back surface layer is 50 μm or less, the amount of convex warping on the surface 12a side of the following layer is further reduced, and chipping tends to be suppressed.

[0022] The tensile modulus of the back surface layer is preferably 2.0 to 5.0 GPa, 2.5 to 4.5 GPa, or 3.0 to 4.0 GPa. When the tensile modulus of the back surface layer is within the above range, rigidity is further improved and the following layer 12 is supported from the back, which tends to reduce warpage and suppress chipping. The tensile modulus can be measured according to JIS K 7127. The tensile modulus can also be adjusted by the material of the back surface layer.

[0023] The heat shrinkage 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 is not particularly limited, but is preferably 0%, and may be 0.1% or more, for example. The heat shrinkage can be measured according to JIS C 2318. When the heat shrinkage varies depending on the measurement direction, the maximum heat shrinkage measured in any direction is meant. Therefore, if the heat shrinkage in the TD direction is 3.5% and the heat shrinkage in the MD direction is 0.1%, the above shrinkage is not satisfied. The heat shrinkage can be adjusted by the material of the back layer, the stretch ratio, etc.

[0024] 1.2.Adhesive layer The adhesive layer 13 may bond the compliant layer 12 to the backing layer 14. The adhesive layer may be an acrylic adhesive or an epoxy adhesive. As an example, the adhesive layer may include a base polymer, an epoxy resin, and a hardener.

[0025] 1.2.1. Base polymer The base polymer is a component that constitutes the main component of the adhesive layer. The base polymer is not particularly limited, but examples thereof include (meth)acrylic acid ester copolymers. The shape of the (meth)acrylic acid ester copolymer is not particularly limited, but examples thereof include linear, branched, or crosslinked shapes. Among these, a crosslinked shape is preferred. By using such a base polymer, the physical properties of the adhesive layer can be adjusted. The crosslinked or branched base polymer may be a base polymer in which epoxy groups or the like of a linear or branched base polymer are bonded via a curing agent, which will be described later.

[0026] The monomer constituting the (meth)acrylic acid ester copolymer is not particularly limited, but examples thereof include (meth)acrylic acid alkyl esters having an alkyl group with 1 to 3 carbon atoms, (meth)acrylic acid esters having a glycidyl group, (meth)acrylic acid esters having a hydroxyl group, and monomers having an aromatic group. The (meth)acrylic acid ester copolymer may also contain a copolymerizable vinyl monomer other than the acrylic monomer.

[0027] The (meth)acrylic acid alkyl ester having an alkyl group having 1 to 3 carbon atoms is not particularly limited, but examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate.

[0028] The content of structural units derived from a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 3 carbon atoms is preferably 75 to 98 mass%, 80 to 97 mass%, 85 to 96 mass%, or 90 to 95 mass% relative to the total amount of the (meth)acrylic acid ester-based copolymer. When the content of structural units derived from a (meth)acrylic acid alkyl ester having an alkyl group is within the above range, adhesion tends to be further improved and the amount of warping tends to be further reduced.

[0029] The (meth)acrylic acid ester having a glycidyl group is not particularly limited, but examples thereof include glycidyl (meth)acrylate and allyl glycidyl ether. A structural unit derived from a (meth)acrylic acid ester having a glycidyl group may be used for the purpose of introducing an epoxy group into a base polymer. When the epoxy group introduced into the base polymer reacts with a curing agent described below, the base polymers bond to each other and are crosslinked three-dimensionally.

[0030] The content of the structural units derived from a (meth)acrylic acid ester having a glycidyl group is preferably 0.5 to 9.0 mass%, 1.0 to 7.0 mass%, or 2.0 to 6.0 mass%, relative to the total amount of the (meth)acrylic acid ester copolymer. When the content of the structural units derived from a (meth)acrylic acid ester having a glycidyl group is within the above range, the crosslink density of the base polymer is controlled, which tends to further improve adhesion and further reduce warpage.

[0031] The (meth)acrylic acid ester having a hydroxyl group is not particularly limited, but examples thereof include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, pentaerythritol triacrylate, glycidol di(meth)acrylate, and dipentaerythritol pentaacrylate. A structural unit derived from a (meth)acrylic acid ester having a hydroxyl group may be used for the purpose of introducing an epoxy group into a base polymer. The hydroxyl group introduced into the base polymer reacts with a curing agent described below, causing the base polymers to bond together and crosslink three-dimensionally.

[0032] The content of the structural units derived from a (meth)acrylic acid ester having a hydroxyl group is preferably 1.0 to 12.5 mass%, 2.0 to 10 mass%, or 3.0 to 7.0 mass%, relative to the total amount of the (meth)acrylic acid ester copolymer. When the content of the structural units derived from a (meth)acrylic acid ester having a hydroxyl group is within the above range, the crosslink density of the base polymer is controlled, which tends to further improve adhesion and further reduce warpage.

[0033] The monomer having an aromatic group is not particularly limited, but examples thereof include styrene, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate.

[0034] When the structural units of the base polymer have the above composition, the adhesiveness is further improved and the amount of warping tends to be further reduced.

[0035] The content of the base polymer is preferably 75 to 94 mass %, 80 to 92 mass %, or 82 to 88 mass % relative to the total amount of the adhesive layer. When the content of the base polymer is within the above range, adhesion is further improved and the amount of warping tends to be further reduced.

[0036] 1.2.2. Multifunctional epoxy compounds The polyfunctional epoxy compound is not particularly limited, but examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, naphthol novolac type epoxy resin, dihydroxybenzene type epoxy resin, and tetramethylbiphenol type epoxy resin.

[0037] 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, adhesion is further improved and the amount of warping tends to be further reduced.

[0038] 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.

[0039] 1.2.3. Hardener The curing agent can be amine-based compounds, acid anhydride-based compounds, amide-based compounds, or phenol-based compounds.These curing agents are not particularly limited, but can be exemplified by diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, polyamide resin synthesized by linolenic acid dimer and ethylenediamine, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol novolak, and their modified products, imidazole-based compounds, guanidine derivatives, etc.

[0040] 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, adhesion is further improved and the amount of warping tends to be further reduced.

[0041] 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.

[0042] 1.3. Follower layer The conforming layer 12 conforms to the irregularities 22 of the wafer 20, protecting the irregularities from damage during the wafer processing, and also contributes to improving adhesion by preventing gaps from forming between the release layer and the semiconductor element forming surface 20a due to its high conforming ability. On the other hand, because such a conforming layer 12 has high adhesion, it tends to leave adhesive residue when in direct contact with the wafer 20, but by providing the release layer 11 described below, contamination by tape residue is less likely to occur.

[0043] The following layer preferably contains a resin. The resin is not particularly limited, but examples thereof include ionomer resin, polyvinyl chloride, polyethylene terephthalate, ethylene-vinyl acetate copolymer, ethylene-acrylic acid-acrylic acid ester film, ethylene-ethyl acrylate copolymer, polyethylene, polypropylene, propylene copolymer, and ethylene-acrylic acid copolymer. These resins may be used alone or in combination of two or more. More specifically, the following resins may be a mixture, copolymer, or laminate of one resin with another.

[0044] Ionomer resins have a cross-linked structure formed by metal ions, and therefore can maintain shape stability even when exposed to temporary or localized high temperatures, such as those encountered during semiconductor processing.

[0045] The ionomer resin is not particularly limited as long as it is a resin in which a predetermined polymer is intermolecularly bonded by a metal ion, and examples thereof include polyolefin-based ionomers, (meth)acrylic ionomers, polystyrene-based ionomers, and polyester-based ionomers. These ionomer resins may be used alone or in combination of two or more. Among these, polyolefin-based ionomers and (meth)acrylic ionomers are preferred, and (meth)acrylic ionomers are more preferred.

[0046] The polyolefin ionomer is not particularly limited, but examples thereof include ethylene-methacrylate copolymer, ethylene-acrylate copolymer, and ethylene-methacrylate-acrylate copolymer.

[0047] The (meth)acrylic ionomer is not particularly limited, but examples thereof include an acrylic acid ester-acrylate copolymer, an acrylic acid ester-methacrylate copolymer, a methacrylic acid ester-acrylate copolymer, and a methacrylic acid ester-methacrylate copolymer.

[0048] The polystyrene ionomer is not particularly limited, but examples thereof include a styrene-styrene sulfonate copolymer, a styrene-acrylate copolymer, a styrene-methacrylate copolymer, a styrene-styrene carboxylate copolymer, and a styrene-N-methyl 4-vinylpyridinium salt copolymer.

[0049] The polyester ionomer is not particularly limited, but examples thereof include sulfoterephthalic acid salt copolymerized polyethylene terephthalate, sulfoisophthalic acid salt copolymerized polyethylene terephthalate, sulfoterephthalic acid copolymerized polybutylene terephthalate, and sulfoisophthalic acid copolymerized polybutylene terephthalate.

[0050] The metal ions constituting the salt of the ionomer resin are not particularly limited, but examples thereof include monovalent metal ions such as sodium ions and lithium ions; divalent metal ions such as zinc ions, calcium ions, 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 group in the polymer and the valence of the metal ions.

[0051] The resin may contain an elastomer. Examples of the elastomer include, but are not limited to, natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, silicone rubber, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resin such as 6-nylon and 6,6-nylon, (meth)acrylic resin, polyester resin such as polyethylene terephthalate and polybutylene terephthalate, polyamideimide resin, fluororesin, and phenoxy resin. These elastomers may be used alone or in combination.

[0052] The content of the resin is preferably 80 to 100 mass %, 85 to 100 mass %, or 90 to 100 mass % relative to the total amount of the follow-up layer.

[0053] The following layer may contain additives other than the resin as needed. Examples of additives include, but are not limited to, plasticizers, heat stabilizers, colorants, organic lubricants, inorganic lubricants, surfactants, processing aids, and antistatic agents. The additives may be used alone or in combination of two or more.

[0054] The thickness of the conformal layer is preferably 50 to 500 μm, 75 to 400 μm, 70 to 300 μm, or 100 to 250 μm. Having a conformal layer thickness within the above range tends to further reduce the amount of warping and suppress chipping. Furthermore, having a conformal layer thickness within the above range tends to further improve conformability to wafer irregularities and also to reduce the likelihood of voids or the like being trapped between the wafer processing tape and the semiconductor element formation surface, thereby tending to improve adhesion.

[0055] 1.4.Release layer The release layer 11 is a layer laminated on the conformal layer 12. During the semiconductor processing process, the release layer 11 adheres to the wafer 20 to protect the semiconductor element forming surface 20a, and can be peeled off after the process without leaving any adhesive residue.

[0056] The release layer may contain a base polymer, a monomer, a photopolymerization initiator, and a curing agent. By including the monomer and the photopolymerization initiator, after the wafer processing tape is attached to the wafer and a predetermined semiconductor processing process is performed, a polymerization reaction occurs in the release layer by irradiating light, and the adhesion of the release layer to the semiconductor element formation surface of the wafer is reduced. By controlling the adhesion in this way, contamination due to water-related contamination can be suppressed in semiconductor processing processes that require adhesion, such as the backgrinding step S2 and the dicing step S3 described below, and contamination due to tape residue can be further suppressed by reducing the adhesion in the peeling step S4.

[0057] 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 thickness of the release layer is 0.2 μm or more, the amount of convex warping on the surface 12a side of the follower layer is further reduced, and chipping tends to be suppressed. Furthermore, when the thickness of the release layer is 0.2 μm or more, the releasability tends to be further improved. Furthermore, when the thickness of the release layer is 15 μm or less, the amount of concave warping on the surface 12a side of the follower layer is further reduced, and chipping tends to be suppressed.

[0058] The ratio of the thickness of the back surface layer to the thickness of the release layer (back surface layer / release layer) is preferably 1 to 40, 2 to 20, 3 to 15, or 4 to 10. When the thickness ratio (back surface layer / release layer) is within the above range, the convex warp on the surface 12a side of the following layer and the concave warp on the surface 12a side of the following layer are balanced, the amount of warp is further reduced, and chipping tends to be suppressed.

[0059] 1.4.1. Base polymer The base polymer is a component that constitutes the main component of the release layer. The base polymer is not particularly limited, but examples thereof include (meth)acrylic acid ester copolymers. The shape of the (meth)acrylic acid ester copolymer is not particularly limited, but examples thereof include linear, branched, or crosslinked shapes. Among these, a crosslinked shape is preferred. By using such a base polymer, the physical properties of the release layer can be adjusted. The base polymer having a crosslinked or branched shape may be a base polymer in which epoxy groups or the like of a linear or branched shape are bonded via a curing agent, which will be described later.

[0060] The monomer constituting the (meth)acrylic acid ester copolymer is not particularly limited, but examples thereof include (meth)acrylic acid alkyl esters having an alkyl group with 1 to 3 carbon atoms, (meth)acrylic acid esters having a glycidyl group, (meth)acrylic acid esters having a hydroxyl group, and monomers having an aromatic group. The (meth)acrylic acid ester copolymer may also contain a copolymerizable vinyl monomer other than the acrylic monomer.

[0061] The (meth)acrylic acid alkyl ester having an alkyl group having 1 to 3 carbon atoms is not particularly limited, but examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate.

[0062] The content of structural units derived from a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 3 carbon atoms is preferably 75 to 98 mass %, 80 to 97 mass %, 85 to 96 mass %, or 90 to 95 mass % relative to the total amount of the (meth)acrylic acid ester-based copolymer. When the content of structural units derived from a (meth)acrylic acid alkyl ester having an alkyl group is within the above range, the dynamic viscoelasticity of the release layer tends to more easily achieve the above physical properties, and staining due to wet areas and staining due to tape residue tends to be further reduced.

[0063] The (meth)acrylic acid ester having a glycidyl group is not particularly limited, but examples thereof include glycidyl (meth)acrylate and allyl glycidyl ether. A structural unit derived from a (meth)acrylic acid ester having a glycidyl group may be used for the purpose of introducing an epoxy group into a base polymer. When the epoxy group introduced into the base polymer reacts with a curing agent described below, the base polymers bond to each other and are crosslinked three-dimensionally.

[0064] The content of the structural units derived from a (meth)acrylic acid ester having a glycidyl group 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)acrylic acid ester copolymer. When the content of the structural units derived from a (meth)acrylic acid ester having a glycidyl group is within the above range, the crosslink density of the base polymer is controlled, and the dynamic viscoelasticity of the release layer tends to achieve the above physical properties.

[0065] The (meth)acrylic acid ester having a hydroxyl group is not particularly limited, but examples thereof include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, pentaerythritol triacrylate, glycidol di(meth)acrylate, and dipentaerythritol pentaacrylate. A structural unit derived from a (meth)acrylic acid ester having a hydroxyl group may be used for the purpose of introducing an epoxy group into a base polymer. The hydroxyl group introduced into the base polymer reacts with a curing agent described below, causing the base polymers to bond together and crosslink three-dimensionally.

[0066] The content of the structural units derived from a (meth)acrylic acid ester having a hydroxyl group is preferably 1.0 to 12.5 mass%, 2.0 to 10 mass%, or 3.0 to 7.0 mass%, relative to the total amount of the (meth)acrylic acid ester copolymer. When the content of the structural units derived from a (meth)acrylic acid ester having a hydroxyl group is within the above range, the crosslink density of the base polymer is controlled, and the dynamic viscoelasticity of the release layer tends to achieve the above physical properties.

[0067] The monomer having an aromatic group is not particularly limited, but examples thereof include styrene, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate.

[0068] The content of the structural unit derived from a 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%, relative to the total amount of the (meth)acrylic acid ester copolymer.

[0069] When the structural units of the base polymer have the above composition, the dynamic viscoelasticity of the release layer tends to be adjusted to fall within the above range.

[0070] The weight average molecular weight of the base polymer is preferably 1.0×10 4 ~2.0×10 6 is 5.0 × 10 4 ~1.5×10 6 is 1.0 × 10 5 ~1.0×10 6 When the weight average molecular weight of the base polymer is within the above range, the dynamic viscoelasticity of the release layer tends to achieve the above physical properties. 4 When the weight average molecular weight of the base polymer is 2.0×10 or more, the releasability is further improved and contamination due to residues from the tape tends to be further suppressed. 6 By satisfying the condition below, adhesion is further improved and contamination due to wet areas tends to be further suppressed.

[0071] The "weight average molecular weight" described in this specification is the molecular weight measured by using a gel permeation chromatograph analyzer for a sample prepared by dissolving the base polymer in tetrahydrofuran.

[0072] The glass transition temperature of the base polymer is preferably −25 to 15° C., −20 to 10° C., −15 to 5° C., or −10 to 0° C. When the glass transition temperature of the base polymer is −25° C. or higher, releasability is improved and contamination due to residue from the tape tends to be more effectively suppressed. When the glass transition temperature of the base polymer is 15° C. or lower, adhesion is improved and contamination due to wet areas tends to be more effectively suppressed.

[0073] The content of the base polymer is preferably 85 to 98 mass %, 90 to 97 mass %, or 92 to 96 mass % relative to the total amount of the release layer. By having the content of the base polymer within the above range, the dynamic viscoelasticity of the release layer tends to be adjusted to the above range. In addition, contamination due to tape residue and contamination due to wet areas tends to be further suppressed.

[0074] Monomers The release layer may contain a polymerizable compound (monomer). The monomer can change the physical properties of the release layer by undergoing a polymerization reaction with a photopolymerization initiator as described above. Furthermore, the dynamic viscoelasticity of the release layer tends to be adjusted to the above-mentioned range depending on the type and amount of the monomer.

[0075] Such monomers are not particularly limited, but examples thereof include polyfunctional acrylates such as dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, tricyclodecane glycol 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.

[0076] By using a multifunctional acrylate, the monomer undergoes three-dimensional cross-linking through polymerization, which can advantageously change the physical properties of the release layer, and tends to further suppress contamination caused by tape residue.

[0077] The content of the monomer 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 content of the monomer is within the above range, contamination by residues derived from the tape tends to be further suppressed.

[0078] 1.4.3. Photoinitiators The photopolymerization initiator is not particularly limited, but 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 (e.g., thiophenyl group-containing compounds), 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 these, alkylphenone-based photopolymerization initiators are preferred. These photopolymerization initiators may be used alone or in combination of two or more.

[0079] 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 part 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.

[0080] 1.4.4. Hardener The curing agent is not particularly limited, but examples thereof include isocyanate compounds, epoxy compounds, and amine compounds. Among these, isocyanate compounds are preferred. By using such a curing agent, the base polymer is crosslinked, and the dynamic viscoelasticity of the release layer tends to be adjusted to the above-mentioned range.

[0081] The isocyanate compound is not particularly limited, and examples thereof include compounds having a group that reacts with the hydroxyl group or carboxyl group of the base polymer. More specific examples include tolylene diisocyanates such as trimethylolpropane-added tolylene diisocyanate, aromatic diisocyanates such as 4,4-diphenylmethane diisocyanate and xylylene diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate and methylene bis(4-cyclohexyl isocyanate), and aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate. These isocyanate compounds may be used alone or in combination of two or more.

[0082] Among these, the curing agent is preferably a polyfunctional isocyanate compound having two or more functional groups. By using such a curing agent, the multiple base polymers can also be crosslinked by the curing agent.

[0083] The content of the curing agent 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 having the content of the curing agent within the above range, the dynamic viscoelasticity of the release layer is adjusted to the above range, and contamination due to residues derived from the tape and contamination due to wet areas tends to be further suppressed.

[0084] 2. Manufacturing method of wafer processing tape The manufacturing method of the wafer processing tape of this embodiment is not particularly limited, but is not particularly limited as long as it includes, for example, a step of forming a release layer 11 on the surface 12a of the follower layer 12, and may also include a step of forming a back surface layer 14 on the back surface 12b of the follower layer 12, if necessary.

[0085] The method for forming the release layer 11 and the back surface layer 14 is not particularly limited, but for example, films may be dry-laminated together, or a composition may be applied to the surface of the follower layer 12 and then dried or photo-cured to form the release layer 11 and the back surface layer 14. Alternatively, the release layer 11 and the back surface layer 14 may be attached to the follower layer 12 via the adhesive layer 13.

[0086] 2. Wafer processing method The wafer processing method of this embodiment includes a bonding process in which the above-mentioned wafer processing tape is bonded to the element-forming surface of the wafer, and a back-grinding process in which the non-element-forming surface of the wafer bonded to the wafer processing tape is polished, and may also include a dicing process in which the wafer is diced, and a peeling process in which the wafer processing tape is heated and peeled off, as necessary.

[0087] Fig. 2 is a flowchart showing the wafer processing method of this embodiment in the form of a schematic cross section. In the example shown in Fig. 2, a release layer is provided in contact with the device-forming surface of the wafer, but in the case where no release layer is provided, the tracking layer is in contact with the device-forming surface of the wafer.

[0088] 2.1. Bonding process 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.

[0089] In the laminating step, the wafer processing tape 10 may be preheated before being 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 device-forming surface 20a of the wafer in a heated state, the surface 11a of the release layer 11 can be laminated to the device-forming surface 20a of the wafer in a state where it conforms to the surface 11a of the release layer 11 (see S2 in FIG. 2). In this way, the protrusions 22 are sunk into the wafer processing tape 10, so that the device-forming surface 20a of the wafer having the protrusions 22 can be protected.

[0090] The heating temperature is preferably 60 to 150° C., more preferably 70 to 140° C., and even more preferably 80 to 130° C. The heating time of the wafer processing tape 10 is preferably 3 to 120 seconds, and more preferably 5 to 90 seconds. By keeping the heating conditions within the above range, the conformability of the wafer processing tape 10 tends to be further improved.

[0091] 2.2. Processing process The processing step for processing the wafer 20 in a state where the wafer processing tape 10 and the wafer 20 are bonded together is not particularly limited, and any wafer processing process can be appropriately applied. For example, the processing step may include back grinding, which grinds the back surface 20b of the wafer to which the wafer processing tape 10 is not bonded, to obtain a thinned wafer, or dicing, which dices the wafer 20 to obtain semiconductor chips.

[0092] Furthermore, as a processing process that combines these, there is a method in which a dicing step S3 is performed in which the thinned wafer is diced by blade dicing or the like after the back-grinding step S2, as shown in Fig. 2. In the following, a process in which the dicing step S3 is performed after the back-grinding step S2 will be described, but the present embodiment is not limited to this.

[0093] 2.2.1.Back grinding process The backgrinding step S2 is a step of polishing the non-element-forming surface 20b of the wafer 20 attached to the wafer processing tape 10. Specifically, from the viewpoint of protecting the element-forming surface 20a, the wafer processing tape 10 is attached to the element-forming surface 20a as a backgrinding tape, and the non-element-forming surface 20b of the wafer 20 is ground (backgrinded) to a desired thickness.

[0094] The specific method of back-grinding is not particularly limited, and known methods can be used. For example, a method of grinding while supplying a slurry containing abrasive grains to the back surface 20b of the wafer 20 can be used. The thickness of the thinned wafer obtained by this method is not particularly limited as long as it is a thickness suitable for the processing purpose, but as an example, it is preferably 300 μm or less, 150 μm or less, or 50 μm or less.

[0095] In backgrinding, a load is applied in the thickness direction of the wafer 20, which can easily damage the protrusions 22 and reduce 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, which makes it possible to avoid damage to the protrusions 22 and the like.

[0096] In the wafer processing method of this embodiment, when a wafer has modified portions and grooves formed in advance on its surface for singulation, and a back-grinding process is performed to thin the wafer 20 from the back surface 20b of the wafer 20, the wafer 20 may be thinned to approximately the same depth as the modified portions and grooves. This allows thinning by back-grinding and singulation to be performed simultaneously.

[0097] 2.2.2.Dicing process The dicing step S3 is a step of dicing the wafer 20. The dicing method is not particularly limited, but examples thereof include blade dicing, in which the wafer is cut into semiconductor chips 30 by a dicing blade.

[0098] 2.3. Peeling process 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 picking up the semiconductor chip 30 from the wafer processing tape is also called a pick-up step.

[0099] In the peeling step S4, the wafer processing tape 10 may be peeled off at room temperature, or may be peeled off 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 irradiating it with ultraviolet light before peeling, thereby reducing its adhesive strength to the wafer 20. This tends to further improve the releasability and further suppress contamination due to residues derived from the tape.

[0100] Furthermore, when picking up the semiconductor chip 30 from the wafer processing tape, although not particularly limited, for example, the semiconductor chip 30 may be pushed up by a push-up needle and then picked up by suction using a suction collet.

[0101] Furthermore, during pick-up, an expanding device may be used to stretch the wafer processing tape 10 in the planar direction, and the semiconductor chips 30 may be picked up by a pick-up device in a state where they are separated from each other. [Example]

[0102] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0103] Example 1 (Preparation of Release Layer Composition) 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 were placed in a polymerization vessel, and polymerization was carried out for 4 hours at 60° C. As a result, acrylic polymer 1 having a glass transition temperature of −5° C. and a weight average molecular weight of 600,000 was obtained.

[0104] A composition for a release layer was prepared by mixing 100 parts by mass of acrylic polymer 1, 4 parts by mass of acrylic monomer 1 (manufactured by Kyoeisha Chemical Co., Ltd., product name "Light Acrylate DPE-6A", dipentaerythritol hexaacrylate), 0.4 parts by mass of a photopolymerization initiator (manufactured by IGM, product name "Omnirad-184", α-hydroxyalkylphenone), and 0.5 parts by mass of an isocyanate-based curing agent (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-101E", tolylene diisocyanate).

[0105] (Preparation of Adhesive Layer Composition) Into a polymerization vessel were charged 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.

[0106] A composition for adhesive layer was prepared by mixing 100 parts by mass of acrylic polymer 2 and 4 parts by mass of an isocyanate crosslinking agent (Coronate L-45E, manufactured by Nippon Polyurethane Co., Ltd.).

[0107] (Formation of back surface layer) The backing layer was a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product number: Toyobo Ester Film E5102, thickness 12 μm, tensile modulus of elasticity 4.0 GPa, heat shrinkage rate of 1.5% when heated at 150°C for 30 minutes), and the following layer was an ionomer film (manufactured by Gunze Co., Ltd., product name "Fanclea HMD", thickness 150 μm, storage modulus at 120°C 5.0 × 10 6 Pa) were laminated together with the adhesive layer composition interposed therebetween, and then heated at a drying temperature of 90° C. under a tension of 120 N to form an adhesive layer.

[0108] (Formation of release layer) Then, the release layer composition prepared as described above was applied to the surface opposite the back layer of the ionomer film, and the adhesive layer composition and the release layer composition were irradiated with ultraviolet light using a UV irradiation device (UVC-4800-4, manufactured by Ushio Inc.) under conditions of an illuminance of 160 W and an accumulated irradiation dose of 1280 mJ using high-pressure mercury, thereby causing a curing reaction to proceed and forming a release layer and adhesive layer with a thickness of 2 μm, thereby producing the wafer processing tape of Example 1.

[0109] Example 2 A tape for wafer processing of Example 2 was produced in the same manner as in Example 1, except that the thickness of the follow-up layer was set to 60 μm.

[0110] Example 3 A tape for wafer processing of Example 3 was produced in the same manner as in Example 1, except that the thickness of the follow-up layer was set to 320 μm.

[0111] Example 4 A tape for wafer processing of Example 4 was produced in the same manner as in Example 1, except that the thickness of the release layer was set to 0.3 μm.

[0112] Example 5 A tape for wafer processing of Example 5 was produced in the same manner as in Example 1, except that the thickness of the release layer was set to 12 μm.

[0113] Example 6 A wafer processing tape of Example 6 was produced in the same manner as in Example 1, except that a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product number: Toyobo Ester Film E5102, thickness 12 μm, tensile modulus 4.0 GPa) was replaced with a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product number: Lumirror S10, thickness 38 μm, tensile modulus 4.9 GPa) to make the thickness of the backside layer 38 μm.

[0114] Comparative Example 1 A wafer processing tape of Comparative Example 6 was produced in the same manner as in Example 1, except that the drying temperature when heat-curing the adhesive layer was set to 120° C. and the tension was set to 200 N.

[0115] [Film warpage] A test piece measuring 297 mm x 210 mm was cut out from the wafer processing tape obtained as described above, and placed on a flat stage with the back surface layer facing downwards. The amount of warpage from the stage at the four corners was measured, and the average value was calculated to be the amount of warpage of the film.

[0116] [Evaluation of chipping resistance] Using a tape mounter (DFM-M150, manufactured by Disco) and an 8-inch ring frame, the wafer processing tapes of the examples and comparative examples were bonded to a 5-inch diameter, 300 μm thick Si mirror wafer. Next, using a dual dicer (AW-D-300TX, manufactured by Tokyo Seimitsu) and a blade (ZH05-SD2000-N1-50DC, manufactured by Disco), dicing was performed under the following conditions: spindle rotation: 20,000 rpm, dicing speed: 40 mm / sec, chip size: 2.2 mm x 2.5 mm. Finally, after peeling the tape, the chips were observed using a digital microscope (VHX-900, manufactured by Keyence), and chips with chipped corners were counted as corner cracked products. Chipping resistance was evaluated according to the following evaluation criteria. (Evaluation criteria) A: The number of semiconductor chips in which corner cracks occurred was 0. B: The number of semiconductor chips in which corner cracks occurred was 1 to 10. C: The number of semiconductor chips in which corner cracks occurred was 11 to 100. D: The number of semiconductor chips in which corner cracks occurred was 101 or more.

[0117] [Table 1] [Industrial Applicability]

[0118] The wafer processing tape of the present invention has industrial applicability as a tape used in processing processes such as wafer back grinding and dicing. [Explanation of symbols]

[0119] 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...protrusion, 30...semiconductor chip, S1...bonding process, S2...back grinding process, S3...dicing process, S4...peeling process.

Claims

1. A follow-up layer and a backing layer disposed on the back surface of the follow-up layer, A test piece of 297 mm x 210 mm is cut out and placed on a flat stage with the back surface layer facing downwards. In this state, the average amount of warping from the stage at the four corners is 30 mm or less. Tape for wafer processing.

2. Further comprising a release layer disposed on the surface of the follower layer.

2. The wafer processing tape according to claim 1.

3. Further, an adhesive layer is provided between the follow-up layer and the back surface layer. The wafer processing tape according to claim 1 .

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

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

6. The back surface layer has a heat shrinkage rate of 3.0% or less at 150°C for 30 minutes. The wafer processing tape according to claim 1 .

7. The thickness of the follow-up layer is 50 to 500 μm. The wafer processing tape according to claim 1 .

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

9. a bonding step of bonding the wafer processing tape according to any one of claims 1 to 8 to the element-forming surface of the wafer; a dicing step of dicing the wafer bonded to the wafer processing tape. Wafer processing method.

10. The method further includes a back-grinding step of polishing a non-element-formed surface of the wafer. The wafer processing method according to claim 9.

11. a peeling step of peeling off the wafer processing tape after the back-grinding step; The wafer processing method according to claim 9.

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