Tape for wafer processing and wafer processing method

Abstract

To provide a tape for wafer processing which minimizes contamination from water-related sources in a processing and contamination from tape residue 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 release layer laminated onto the following layer. The storage elastic modulus G20 of the release layer at 20°C is 1.0×107 to 1.0×1010 Pa.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 that 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] Existing wafer processing tapes generally use adhesive to secure the wafer, but the problem of adhesive residue when peeled off is a problem. A completely adhesive-free wafer processing tape would allow semiconductor elements to be formed all over the wafer, right up to the very edge, without having to worry about contamination from tape residue. This would also be expected to increase the yield of semiconductor elements per wafer.

[0007] However, it is not easy to ensure sufficient adhesion using only a release layer on the surface of the wafer processing tape without providing an adhesive layer. If adhesion is poor, liquid components used in the processing process will seep into the gap between the semiconductor element surface of the wafer and the wafer processing tape, causing contamination and actually reducing yield. This type of contamination caused by seepage of liquid components in the processing process is also called "water contamination."

[0008] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a wafer processing tape that is less susceptible to contamination due to water contamination in the processing process and contamination due to tape residue, and a wafer processing method using the wafer processing tape. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above problems, and as a result have found that adhesion can be improved without providing a pressure-sensitive adhesive layer by providing a release layer laminated on a follow-up layer with a predetermined storage modulus, thereby completing the present invention.

[0010] That is, the present invention is as follows. [1] A follow-up layer and a release layer laminated on the follow-up layer, The storage modulus E of the release layer at 23°C 23 But 5.0×10 5 ~2.3×10 8 Pa, Tape for wafer processing. [2] The storage modulus E of the release layer at 120°C 120 But 2.0×10 5 ~3.0×10 6 Pa, The wafer processing tape according to [1]. [3] The storage modulus E of the release layer at 120°C 120 The storage modulus E 23 The ratio (E 23 / E 120 ) is 1.0×10 to 1.0×10 3 That is, The wafer processing tape according to [1] or [2]. [4] The release layer has a peak value of tan δ of 0.9 to 1.3. The tape for wafer processing according to any one of [1] to [3]. [5] Ugh The thickness of the release layer is 0.5 to 10 μm. The tape for wafer processing according to any one of [1] to [4]. [6] a bonding step of bonding the wafer processing tape according to any one of [1] to [5] to the element-forming surface of the wafer; a back grinding step of grinding a non-element forming surface of the wafer bonded to the wafer processing tape, Wafer processing method. [7] The method further includes a dicing step of dicing the wafer. The wafer processing method according to [6]. [8] a peeling step of peeling off the wafer processing tape after the back grinding step; The wafer processing method according to [7] or [8]. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a wafer processing tape that is less susceptible to contamination due to water contamination in the processing process and contamination due to tape residue. [Brief explanation of the drawings]

[0012] [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

[0013] 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.

[0014] 1. Wafer processing tape The wafer processing tape of this embodiment has a follower layer and a release layer laminated on the follower layer, and the storage modulus E at 23° C. of the release layer is 23 But 5.0×10 5 ~2.3×10 8 It is Pa.

[0015] FIG. 1 shows a schematic cross-sectional view of the wafer processing tape of this embodiment. As shown in FIG. 1, the wafer processing tape 10 of this embodiment has a follower layer 12 and a release layer 11 laminated on the follower layer 12. The wafer processing tape of this embodiment may also have a backside layer 13, if necessary, on the surface 12b of the follower layer 12 opposite the surface 12a on which the release layer 11 is laminated. As shown in FIG. 2, the front side 11a (exposed surface) of the release layer 11 adheres closely to the semiconductor element forming surface 20a of the wafer 20, thereby protecting the semiconductor element forming surface 20a of the wafer 20. In this embodiment, the surface of the wafer processing tape and each layer thereof that contacts the wafer is referred to as the front side, and the opposite surface is referred to as the back side.

[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] 1.1.Release layer The release layer 11 is a layer laminated on the surface 12a of the follow-up layer 12. During the semiconductor processing, 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.

[0018] Physical Properties In this embodiment, from the viewpoint of providing adhesiveness to the release layer, the storage modulus E 23 Since the temperature during semiconductor processing is mainly room temperature, the storage modulus E at 23°C is 23 is an index of adhesion during semiconductor processing.

[0019] Storage modulus E of release layer at 23°C 23 is 5.0 x 10 5 ~2.3×10 8 Pa, preferably 1.0 x 10 6 ~2.0×10 8 Pa, 5.0 x 10 6 ~1.5×10 8 Pa, 1.0 x 10 7 ~1.0×10 8 Pa. Storage modulus E 23 is 5.0×10 5 By having a storage modulus E 23 is 2.3 × 10 8 By ensuring that the viscosity is equal to or less than Pa, adhesion is improved and contamination due to wet areas tends to be further suppressed.

[0020] Storage modulus E 23 can be adjusted by the components constituting the release layer, such as the type of base polymer, the type and amount of monomer used, the type and amount of photoinitiator used, and the type and amount of curing agent used, which will be described later.

[0021] In this embodiment, from the viewpoint of providing adhesiveness to the release layer, the storage modulus E 23 Since the bonding temperature is approximately 120°C, the storage modulus E at 120°C is 120 is an index showing the conformability of the release layer to the semiconductor element forming surface. If the conformability of the release layer to the semiconductor element forming surface is high, voids are less likely to be formed between the wafer processing tape and the semiconductor element forming surface, and adhesion is improved. That is, the storage modulus E at 120°C 120 is also an index of adhesion.

[0022] Storage modulus E of release layer at 120℃ 120 is preferably 1.0 x 10 4 ~2.0×10 7 Pa, 5.0 x 10 4 ~1.0×10 7 Pa, 7.5 x 10 4 ~7.5×10 6 Pa, 1.0 x 10 5 ~5.0×10 6 Pa, 2.0 x 10 5 ~3.0×10 6 Pa. Storage modulus E 120 is 1.0×10 4 By having a storage modulus E 120 is 2.0×10 7 By ensuring that the pressure is not more than 100 Pa, the conformability during bonding is improved, which improves the adhesion of the release layer to the wafer and tends to further suppress contamination due to water.

[0023] In addition, the storage modulus E 120 Storage modulus E23 The ratio (E 23 / E 120 ) is preferably 1.0 to 10,000, 5.0 to 5,000, 10 to 1,000, 20 to 500, 30 to 250, or 40 to 100. 23 / E 120 ) is 1.0 or more, the releasability is improved and contamination due to residues from the tape tends to be suppressed. 23 / E 120 ) is 10,000 or less, the adhesion of the release layer to the wafer in the wafer processing process is improved, and contamination due to water areas tends to be further suppressed.

[0024] The peak value of tan δ of the release layer is preferably 0.3 to 2.0, 0.5 to 1.8, 0.7 to 1.5, or 0.9 to 1.3. Here, tan δ is the ratio of the loss modulus to the storage modulus. A larger tan δ indicates that the viscosity of the material is more dominant than the elasticity, while a smaller tan δ indicates that the elasticity of the material is more dominant than the viscosity. Therefore, when the peak value of tan δ is 0.3 or more, viscosity becomes relatively dominant, which tends to improve the adhesion of the release layer to the wafer during the wafer processing and to further suppress contamination due to water. Furthermore, when the peak value of tan δ is 2.0 or less, elasticity becomes relatively dominant, which tends to further improve releasability and further suppress contamination due to tape residue.

[0025] The storage modulus is measured in accordance with the storage modulus in a tensile mode described in JIS K7244-1:1998, except that the temperature conditions are 23°C and 120°C.

[0026] 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. A thickness of 0.2 μm or more tends to further improve releasability and further suppress contamination due to tape residue. Furthermore, a thickness of 15 μm or less tends to further suppress contamination due to water contamination. The reason for this is not particularly limited, but it is thought that a thin release layer excessively conforms to the irregularities of the semiconductor element formation surface, which tends to increase peel strength due to the anchor effect, resulting in cohesive failure of the release layer and the generation of tape residue. On the other hand, a thick release layer is thought to have insufficient conformability to the irregularities of the semiconductor element formation surface, resulting in reduced adhesion and tape lift (peeling), which causes water contamination.

[0027] 1.1.2.Composition The release layer may contain a base polymer, a monomer, a photopolymerization initiator, and a curing agent. By containing the monomer and the photopolymerization initiator, crosslinking is formed in the release layer by a polymerization reaction when the release layer formed on the follower layer is irradiated with light in advance. The release layer obtained in this manner has improved releasability from the semiconductor element forming surface of the wafer and tends to further suppress contamination by tape residue.

[0028] 1.1.2.1. 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The monomer having an aromatic group is not particularly limited, but examples thereof include styrene, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 1.1.2.3. Photopolymerization initiator 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.

[0048] 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.

[0049] 1.1.2.4. 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.

[0050] 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.

[0051] Among these, the curing agent is preferably a polyfunctional isocyanate compound having two or more functional groups, which allows the curing agent to crosslink the plurality of base polymers.

[0052] 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.

[0053] 1.2. 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 the presence of the release layer 11 makes it less likely for contamination due to tape residue to occur.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] The polyolefin ionomer is not particularly limited, but examples thereof include ethylene-methacrylate copolymer, ethylene-acrylate copolymer, and ethylene-methacrylate-acrylate copolymer.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] The thickness of the conformal layer is preferably 50 to 500 μm, 75 to 400 μm, or 100 to 300 μm. When the thickness of the conformal layer is within the above range, conformability to the irregularities of the wafer is further improved, and voids are less likely to be formed between the wafer processing tape and the semiconductor element forming surface, tending to improve adhesion.

[0066] 1.3.Backing layer The back surface layer 13 is a layer laminated on the back surface 12b of the follower layer 12. In the peeling process of peeling the wafer 20 or the semiconductor chip 30 from the wafer processing tape, the back surface layer 13 provides rigidity to the follower layer 12 or the release layer 11 and supports them from behind, thereby preventing the follower layer 12 or the release layer 11 from following the wafer 20 or the semiconductor chip 30 being peeled off. This tends to further improve peelability.

[0067] Examples of the back layer include polyester films such as polyethylene terephthalate, polyimide films, and polyamide films such as nylon.

[0068] The elastic modulus of the back surface layer is preferably 1.5 to 7.0 GPa, 2.0 to 6.0 GPa, or 3.0 to 5.0 GPa. When the elastic modulus of the back surface layer is within the above range, the releasability tends to be further improved. The elastic modulus can be measured by the method described in ASTM D882.

[0069] The thickness of the back surface layer is preferably 5 to 50 μm, 7.5 to 40 μm, or 10 to 30 μm. When the thickness of the back surface layer is within the above range, the releasability tends to be further improved.

[0070] 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 layer 13 on the back surface 12b of the follower layer 12, if necessary.

[0071] The method for forming the release layer 11 and the back surface layer 13 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 photocured to form the release layer 11 and the back surface layer 13. Alternatively, the release layer 11 and the back surface layer 13 may be attached to the follower layer 12 via an adhesive layer.

[0072] 3. Wafer processing method The wafer processing method of this embodiment includes a laminating step of laminating the wafer processing tape to the device-formed surface of the wafer, a back-grinding step of polishing the non-device-formed surface of the wafer that has been laminated to the wafer processing tape, and may optionally include a dicing step of dicing the wafer and a peeling step of heating and peeling off the wafer processing tape. Figure 2 shows a flowchart illustrating the wafer processing method of this embodiment with schematic cross-sectional views.

[0073] 3.1. 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.

[0074] 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.

[0075] 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.

[0076] 3.2. 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.

[0077] 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.

[0078] 3.2.1.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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 3.2.2.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.

[0083] 3.3. 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.

[0084] 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.

[0085] 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.

[0086] 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]

[0087] 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.

[0088] 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.

[0089] 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).

[0090] (Formation of back surface layer) The back layer was a polyethylene terephthalate film (manufactured by Toray, product number: E5102, thickness 12 μm, elastic modulus 3.9 GPa), and the follow-up layer was an ionomer film, a metal ion crosslinked ethylene-methacrylic acid copolymer (manufactured by Gunze Co., Ltd., product name "Fanclea HMD", thickness 150 μm, storage modulus at 120 °C 5.0 × 10 6 Pa) were laminated by dry lamination.

[0091] (Formation of release layer) The release layer composition prepared as described above was applied to the surface opposite to the surface on which the back layer of the ionomer film was formed, and the release layer composition was irradiated with ultraviolet light using a UV irradiation device (UVC-4800-4, manufactured by Ushio Inc.) at a high-pressure mercury illumination intensity of 160 W and a cumulative irradiation dose of 1280 mJ, causing a curing reaction to proceed and forming a release layer 2 μm thick, thereby producing the wafer processing tape of Example 1.

[0092] 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 release layer was set to 0.3 μm.

[0093] 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 release layer was set to 12 μm.

[0094] Example 4 A tape for wafer processing of Example 4 was produced in the same manner as in Example 1, except that the amount of acrylic monomer 1 used was 10 parts by mass and no isocyanate-based curing agent was used.

[0095] Example 5 A wafer processing tape of Example 4 was produced in the same manner as in Example 1, except that no isocyanate-based curing agent was used.

[0096] Example 6 A tape for wafer processing of Example 6 was produced in the same manner as in Example 1, except that acrylic monomer 1, photopolymerization initiator, and isocyanate-based curing agent were not used and ultraviolet irradiation was not performed.

[0097] Example 7 A tape for wafer processing of Example 7 was produced in the same manner as in Example 1, except that the amount of acrylic monomer 1 used was 10 parts by mass.

[0098] Example 8 The wafer processing tape of Example 8 was produced in the same manner as in Example 1, except that 24 parts by mass of acrylic monomer 2 (manufactured by Kyoeisha Chemical Co., Ltd., product name "Light Acrylate 1.9-ND-A", 1,9-nonanediol diacrylate) was used instead of acrylic monomer 1.

[0099] Example 9 A wafer processing tape of Example 9 was produced in the same manner as in Example 1, except that 100 parts by mass of acrylic polymer 3 (manufactured by Toray Coatex Co., Ltd., product name "S-6522M", glass transition temperature 3°C, weight average molecular weight 400,000) was used instead of acrylic polymer 1, and acrylic monomer 1, photopolymerization initiator, and isocyanate-based curing agent were not used, and ultraviolet irradiation was not performed.

[0100] Comparative Example 1 77 parts by mass of butyl acrylate, 15 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 were placed in a polymerization vessel, and polymerization was carried out for 4 hours at 60° C. As a result, acrylic polymer 2 having a glass transition temperature of −30° C. and a weight average molecular weight of 600,000 was obtained.

[0101] A wafer processing tape of Comparative Example 1 was produced in the same manner as in Example 1, except that 100 parts by mass of acrylic polymer 2 was used instead of acrylic polymer 1, acrylic monomer 1, photopolymerization initiator, and isocyanate-based curing agent were not used, and ultraviolet irradiation was not performed.

[0102] Comparative Example 2 A tape for wafer processing of Comparative Example 2 was produced by the same procedure as in Example 1, except that the amount of acrylic monomer 1 used was 10 parts by mass and the amount of isocyanate-based curing agent used was 10 parts by mass.

[0103] [Storage modulus measurement] A release layer composition was applied to the release-treated surface of a release-treated polyethylene terephthalate film and dried at 100°C for 1 minute to obtain an 80µm release layer. Next, using a UV irradiation device (UVC-4800-4, manufactured by Ushio Inc.), the release layer was irradiated with ultraviolet light using high-pressure mercury at an illuminance of 160W and an accumulated irradiation dose of 1280mJ to cause a curing reaction. After that, the film was cut into a width of 5mm x length of 100mm to prepare a test piece for measuring the storage modulus of the release layer.

[0104] The storage modulus was measured using a dynamic viscoelasticity measuring device (RSA III, manufactured by TA Instruments) in tension mode, with a frequency of 1 Hz, a strain of 0.07%, and a temperature increase rate of 3°C / min from 0 to 150°C. The storage modulus at 23°C and 120°C, as well as the ratio of the 23°C storage modulus to the 120°C storage modulus, and the peak values ​​of tanδ (loss modulus / storage modulus) were obtained.

[0105] [Pollution assessment] 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 at a spindle rotation of 20,000 rpm, a dicing speed of 40 mm / sec, and a chip size of 2.2 mm x 2.5 mm. Finally, after the tape was peeled off, the wafer processing tape-bonded surface of the chip was observed using a digital microscope (VHX-900, manufactured by Keyence). Chips found to be contaminated (tape residue) due to intrusion of grinding water (water area) or residue on the chip of the tape release layer (cohesive failure or interfacial peeling from the substrate) were counted as contaminated chips. The staining caused by water and staining caused by tape residue due to insufficient adhesion were evaluated according to the following evaluation criteria. (Evaluation criteria) A: 0 contaminated chips B: The number of contaminated chips is between 1 and 10 C: The number of contaminated chips is between 11 and 100. D: 101 or more contaminated chips

[0106] [Table 1] [Industrial Applicability]

[0107] 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]

[0108] 10...wafer processing tape, 11...release layer, 11a...surface, 12...following layer, 12a...surface, 12b...back surface, 13...back surface 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 release layer laminated on the follow-up layer, The storage modulus E of the release layer at 23°C 23 But 5.0 x 10 5 ~2.3 x 10 8 Pa, Tape for wafer processing.

2. The storage modulus E of the release layer at 120°C 120 But 2.0 x 10 5 ~3.0 x 10 6 Pa, The wafer processing tape according to claim 1 .

3. The storage modulus E of the release layer at 120°C 120 The storage modulus E 23 The ratio (E 23 / E 120 ) is 10 to 1000, The wafer processing tape according to claim 1 .

4. the release layer has a peak value of tan δ of 0.9 to 1.3; The wafer processing tape according to claim 1 .

5. The thickness of the release layer is 0.5 to 10 μm. The wafer processing tape according to claim 1 .

6. a bonding step of bonding the wafer processing tape according to any one of claims 1 to 6 to an element-forming surface of a wafer; a back grinding step of grinding a non-element forming surface of the wafer bonded to the wafer processing tape, Wafer processing method.

7. The method further includes a dicing step of dicing the wafer. The wafer processing method according to claim 6.

8. a peeling step of peeling off the wafer processing tape after the back grinding step; The wafer processing method according to claim 6.

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