Adhesive tape, tape for semiconductor wafer processing

Abstract

An adhesive tape that has a substrate layer and an adhesive layer that is provided on the substrate layer. At 23°C–150°C, the loss modulus G" of the adhesive layer is 1.0×102–1.6×105 Pa, and, at the same temperatures, the minimum value M1 of the difference (G'-G") between the storage modulus G' and the loss modulus G" of the adhesive layer is at least 1.0×105 Pa.

Description

Technical Field

[0001] The present invention relates to an adhesive tape and a tape for semiconductor wafer processing.

Background Art

[0002] As manufacturing processes of semiconductor chips, there are a dicing process of separating a semiconductor wafer into individual chips and a die bonding process of bonding the separated chips to a lead frame, a package substrate, or the like. In a stacked package, in the die bonding process, semiconductor chips may be stacked and bonded to each other.

[0003] In such manufacturing processes of semiconductor chips, in recent years, a multilayer adhesive sheet (dicing / die bonding integrated tape) that combines the function of a die bonding film used for bonding a semiconductor chip to a lead frame or the like with a dicing tape used for fixing a semiconductor wafer in the dicing process has been mainly used. (See Patent Documents 1 to 3)

[0004] In the manufacturing process of semiconductor chips, the dicing / die bonding integrated tape fixes the wafer so that the cut chips do not scatter in the process of dicing the semiconductor wafer. While a high adhesive force for strongly fixing the wafer is required, in the process of picking up the chips, it is required that the adhesive force can be lowered so that the chips can be easily peeled off.

[0005] For example, in Patent Documents 1 and 2, by using a photocurable adhesive for the adhesive tape, the adhesive force of the adhesive layer is reduced by light irradiation after dicing and then used for the pick-up process. Thereby, it has been proposed to achieve both the high adhesive force required during dicing and the low adhesive force required during pick-up. Further, for example, in Patent Document 3, it has been proposed to achieve both the high adhesive force required during dicing and the low adhesive force required during pick-up by adding a (meth)acrylic modified product of a silicone resin.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, those described in Patent Documents 1 and 2 require a sufficient adhesive force to prevent the wafer from peeling during dicing, so the adhesive force is too high and cannot fully meet the requirement of being easily peeled off during pickup. Also, even if the chip could be picked up, the force applied during pickup had to be increased, which risked process defects such as chip chipping.

[0008] Especially in recent years, with the higher density and smaller size of packages, the thickness of the wafer has become thinner and the chip size has become smaller, making the above problems more prominent. In response to this, there is a method of adding a low molecular weight component to the adhesive layer for the purpose of reducing pickup defects. However, the added low molecular weight component may precipitate on the surface of the adhesive, making it easier to cause peeling from the ring frame, and it may not be possible to maintain a sufficient adhesive force to prevent the wafer from peeling during dicing, resulting in chip flying.

[0009] On the other hand, for the adhesive tape described in Patent Document 3, a method of adding a silicone-based release agent has been proposed, but there is a risk that the adhesive layer will be contaminated due to migration to the adhesive.

[0010] In addition, in the case of conventional materials, chips fragmented due to the influence of cutting water or the like during blade dicing may peel off, or the adhesive layer may melt due to frictional heat with the blade, and the picked-up paste may fix the chips, resulting in a possible decrease in pick-up performance. During dicing, a high shear force is generated in the adhesive layer, and the influence of friction between the blade and the adhesive layer becomes more prominent. Therefore, in the case of small chip applications, the characteristics are insufficient.

[0011] The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive tape that can be easily picked up without melting of the adhesive layer during dicing, and can suppress chip flying and peeling from the ring frame during dicing, and a tape for semiconductor wafer processing suitable for a blade dicing method using the same.

Means for Solving the Problems

[0012] The inventors of the present invention have intensively studied the adhesive design of the adhesive tape in order to solve the above problems. As a result, it has been found that the above problems can be solved by using an adhesive layer having a predetermined storage elastic modulus and loss elastic modulus.

[0013] That is, the present invention is as follows. [1] Having a base material layer and an adhesive layer provided on the base material layer, In the temperature range of 23°C to 150°C, The loss elastic modulus G” of the adhesive layer is 1.0×10 2 Pa or more and 1.6×10 5 Pa or less, and The minimum value M of the difference (G’-G”) between the storage elastic modulus G’ and the loss elastic modulus G” of the adhesive layer at the same temperature 1 Is 1.0×10 5 Pa or more, Adhesive tape. [2] The Young's modulus of the adhesive layer is 0.5 MPa or more and 7.0 MPa or less, The adhesive tape according to [1]. [3] The 180° peel strength of the adhesive layer from the silicon wafer under the temperature condition of 23°C is 0.03 N / 20 mm or more and 0.35 N / 20 mm or less. The pressure-sensitive adhesive tape according to [1] or [2]. [4] The tack of the adhesive layer under the temperature condition of 23°C is 0.03 N / 20 mm 2 or more and 0.65 N / 20 mm 2 or less. The pressure-sensitive adhesive tape according to any one of [1] to [3]. [5] In the temperature range of 70°C to 110°C, the minimum value M of the difference (G’ - G”) between the storage modulus G’ and the loss modulus G” at the same temperature 2 is 1.0×10 5 Pa or more. The pressure-sensitive adhesive tape according to any one of [1] to [4]. [6] The adhesive layer contains a (meth)acrylate copolymer, and the (meth)acrylate copolymer has a linear shape, a branched shape, or a crosslinked shape. The pressure-sensitive adhesive tape according to any one of [1] to [5]. [7] In the (meth)acrylate copolymer, the content of the structural unit having a hydroxyl group is 1.0 mol% or more and 30 mol% or less with respect to 100 mol% of all the structural units, and the content of the structural unit having a carboxyl group is 0.1 mol% or more and 10 mol% or less with respect to 100 mol% of all the structural units. The pressure-sensitive adhesive tape according to [6]. [8] The adhesive layer further contains a curing agent. The pressure-sensitive adhesive tape according to any one of [1] to [7]. [9] The curing agent contains an isocyanate compound. The pressure-sensitive adhesive tape according to [8].

[10] The isocyanate compound contains a polyfunctional isocyanate compound having two or more functional groups. The pressure-sensitive adhesive tape described in [9].

[11] The pressure-sensitive adhesive tape according to any one of [1] to

[10] , and a die bonding film laminated on the adhesive layer of the pressure-sensitive adhesive tape. A tape for semiconductor wafer processing. [Advantages of the Invention]

[0014] According to the present invention, it is possible to provide a pressure-sensitive adhesive tape that does not melt the adhesive layer during dicing and can be easily picked up, and that can suppress chip jumping and peeling from the ring frame during dicing, and a tape for semiconductor wafer processing using the same. [Embodiments for Carrying Out the Invention]

[0015] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail, but the present invention is not limited thereto, and various modifications are possible without departing from the gist thereof.

[0016] [Pressure-Sensitive Adhesive Tape] The pressure-sensitive adhesive tape according to the present embodiment has a base material layer and an adhesive layer provided on the base material layer, and in the temperature range of 23°C to 150°C, the loss modulus of the adhesive layer is 1.0×10 2 Pa or more and 1.6×10 5 Pa or less, and the minimum value M of the difference (G'-G") between the storage modulus G' and the loss modulus G" of the adhesive layer at the same temperature 1 is 1.0×10 5 Pa or more.

[0017] In a conventional pressure-sensitive adhesive tape, if the adhesive strength is improved so that the wafer does not peel off during dicing, it becomes difficult to peel off the diced chips during pickup. In particular, the adhesive layer scraped up by the frictional heat of the dicing blade fixes the chip more firmly, resulting in a more significant decrease in pick-up performance. Furthermore, since the force required to peel off the chip also increases, chipping of the chip is likely to occur. Conversely, if the peelability during pickup is improved, chip flying and the like are likely to occur during dicing.

[0018] On the other hand, the adhesive tape of the present embodiment has predetermined viscoelastic properties, so that it has excellent melt resistance of the adhesive layer during dicing, improved chip holding properties and peel resistance from the ring frame, and also has improved pick-up performance during pick-up. Each configuration will be described in detail below.

[0019] (Adhesive layer) The adhesive layer of the adhesive tape of the present embodiment has predetermined dynamic viscoelastic properties, so that the generation of high shear force in the adhesive layer can be suppressed during dicing. As a result, the friction generated between the blade and the adhesive layer is reduced, and the melting of the adhesive can be suppressed. In addition, since the scraping of the paste due to the melting of the adhesive is reduced, the fixing of the chip by the scraped paste can also be suppressed, and the pick-up performance is good.

[0020] (Loss elastic modulus G'') The loss elastic modulus G'' of the adhesive layer in the temperature range of 23°C to 150°C is 1.0×10 2 ~1.6×10 5 Pa, preferably 1.0×10 3 ~9.0×10 3 Pa, more preferably 4.0×10 3 ~8.0×10 3 Pa. When the loss elastic modulus G'' of the adhesive layer at 23°C to 150°C is 1.0×10 2By being Pa or more, peeling of the wafer during dicing can be suppressed, and chip flying can be further suppressed. On the other hand, when the loss elastic modulus G” is less than 1.0×10 2 Pa, the adhesion force to the wafer during dicing is insufficient, and it may not be possible to maintain sufficient chip holding force, resulting in chip flying. Also, when the loss elastic modulus G” is 1.6×10 5 Pa or less, it is possible to suppress the adhesion agent melted by the friction between the dicing blade and the adhesive layer from being scraped up during dicing, and it is possible to suppress the chip from being fixed by the scraped-up adhesion agent. On the other hand, when the loss elastic modulus G” is greater than 1.6×10 5 Pa, the adhesion agent is scraped up, so the chip is likely to be fixed, and there is a risk that the pick-up property will deteriorate.

[0021] (The minimum value M of the difference (G’ - G”) between the storage elastic modulus G’ and the loss elastic modulus G”) 1 ) In the temperature range of 23°C to 150°C, the minimum value M of the difference (G’ - G”) between the storage elastic modulus G’ and the loss elastic modulus G” of the adhesive layer at the same temperature 1 is 1.0×10 5 Pa or more, preferably 5.0×10 5 Pa or more, more preferably 1.0×10 6 Pa or more. Also, the upper limit of the minimum value M 1 is preferably 8.0×10 5 Pa or less, more preferably 7.0×10 5 Pa or less, and even more preferably 6.0×10 5 Pa or less. When the minimum value M 1 is 1.0×10 5 Pa or more, the friction between the dicing blade and the adhesive layer is less likely to occur during dicing, and the melted adhesive is suppressed from being scraped up. Therefore, it is possible to suppress the chip from being fixed by the scraped-up adhesive. On the other hand, when the minimum value M 1 is 1.0×10 5If it is less than Pa, high shear force will be generated in the adhesive layer during dicing, friction is likely to occur between the dicing blade and the adhesive layer, and the adhesive is likely to be melted and scraped up. Therefore, the chip is fixed and the pick-up property deteriorates.

[0022] The minimum value M of the difference (G’ - G”) between the storage elastic modulus G’ and the loss elastic modulus G” of the adhesive layer at the same temperature in the temperature range of 70°C to 110°C 2 is preferably 1.0×10 5 Pa or more, more preferably 1.5×10 5 ~8.0×10 5 Pa, and even more preferably 2.5×10 5 ~7.0×10 5 Pa. During dicing, the frictional heat of the dicing blade is about 80°C. Therefore, when the minimum value M 2 is within the above range, the melt resistance, chip holding property, and peel resistance from the ring frame of the adhesive layer during dicing are improved, and the pick-up property during pick-up tends to be further improved.

[0023] The "loss elastic modulus G”" and "storage elastic modulus G’" described in this specification can be obtained by measuring with an adhesive cut out to a predetermined size under the temperature conditions of a temperature range of 23°C to 150°C, a temperature increase rate of 3°C / min, a frequency of 1 Hz, and a shear mode.

[0024] (Young's modulus) The Young's modulus of the adhesive layer is preferably 0.5 to 7.0 MPa, more preferably 1.0 to 5.5 MPa, and even more preferably 2.0 to 4.0 MPa.

[0025] When the Young's modulus of the adhesive layer is within the above range, it is possible to prevent the shaking of the adhesive due to the vibration during dicing, and the peeling of the adhesive due to the vibration from the ring frame tends to be suppressed. In particular, when the Young's modulus is 0.5 MPa or more, the adhesive tends to become hard, and it is more likely to suppress the occurrence of chip chipping caused by the chip shaking due to the vibration during dicing and colliding with the blade. Also, when the Young's modulus is 7.0 MPa or less, the adhesive tends to become soft, and it is more likely to suppress the peeling of the adhesive from the ring frame due to the vibration or cutting water during dicing without following the ring frame.

[0026] The "Young's modulus" described in this specification is the Young's modulus measured by a universal tensile testing machine at a temperature of 23°C, a tensile speed of 5 mm / min, and a chuck distance of 50 mm using an adhesive cut into a width of 1 cm, a length of 10 cm, and a thickness of 60 to 110 μm.

[0027] (180° peel strength) The 180° peel strength of the adhesive layer against the silicon wafer under the temperature condition of 23°C (hereinafter, also simply referred to as "180° peel strength") is preferably 0.03 to 0.35 N / 20 mm, more preferably 0.05 to 0.20 N / 20 mm, and even more preferably 0.08 to 0.12 N / 20 mm or less.

[0028] When the 180° peel strength of the adhesive layer is within the above range, the fragmented chips can be easily peeled off, so the pick-up property tends to be further improved. In particular, when the 180° peel strength is 0.03 N / 20 mm or more, the adhesive force tends to be stronger, making it difficult to peel off from the ring frame, and the adhesion of the wafer can be maintained during dicing, and chip jumping tends to be more suppressed. Also, when the 180° peel strength is 0.30 N / 20 mm or less, the adhesive force tends to be smaller, and the peelability of the fragmented chips during pick-up tends to be further improved. Furthermore, when the 180° peel strength is 0.30 N / 20 mm or less, pick-up is possible even with a weak force applied to the chip during pick-up, so chip breakage tends to be suppressed.

[0029] The "180° peel strength with respect to a silicon wafer" described in this specification can be measured in accordance with the method for measuring adhesive force in JIS Z0237 (2009). Specifically, the adhesive layer is pressure-bonded to a adherend (silicon wafer) with a cleaned surface using a pressure-bonding device (roller mass: 2 kg), and the adhesive force when peeled at 180° with respect to the adherend is measured with a universal tensile testing machine in an environment of 23°C and 50% humidity.

[0030] In this embodiment, the adhesive layer adheres to a ring frame, a die bonding film, etc., and does not directly contact the adherend (silicon wafer). However, the adhesive characteristics of the adhesive layer may generally be indicated by the 180° peel strength with respect to a silicon wafer as a comparable parameter. Therefore, in this embodiment as well, the 180° peel strength with respect to a silicon wafer is adopted as one criterion for indicating the adhesive force with respect to the base material or die bonding film.

[0031] (Tack) The tack of the adhesive layer under the temperature condition of 23°C (hereinafter simply referred to as "tack") is preferably 0.03 to 0.65 N / 20 mm 2 and more preferably 0.05 to 0.60 N / 20 mm 2and more preferably 0.10 to 0.50 N / 20 mm 2 and more preferably 0.20 to 0.40 N / 20 mm 2 It is.

[0032] When the tack of the adhesive layer is within the above range, the adhesive follows the wafer, and there is a tendency to suppress chip jumping during dicing. In particular, when the tack is 0.05 N / 20 mm 2 or more, peeling from the ring frame is more suppressed, and there is a tendency to more suppress chip jumping during dicing. Also, when the tack is 0.60 N / 20 mm 2 or less, the pick-up property is further improved, and there is a tendency to more suppress glue residue on the picked-up chip.

[0033] The "tack" described in this specification is the tack measured by a probe tack tester under the temperature condition of 23°C for an adhesive tape cut out to a width of 1 cm.

[0034] (Composition) The adhesive layer contains, for example, a polymer and a curing agent, and may contain other components as necessary.

[0035] (Polymer) The polymer contained in the adhesive layer is not particularly limited, and examples thereof include (meth)acrylic acid ester copolymers having a linear shape, a branched shape, or a crosslinked shape. Here, the branches of the branched polymer include short-chain branches that are branches with a length of several carbon atoms and long-chain branches that are branches with a length comparable to the main chain. In addition, the crosslinked polymer may have a three-dimensional network structure. Note that the crosslinked polymer also includes those formed by the reaction of a curing agent and a polymer described later.

[0036] (Meth)acrylate copolymers include structural units having an alkyl group, a hydroxyl group, a carboxyl group, and other structural units. These structural units mainly originate from (meth)acrylic acid monomers or (meth)acrylate monomers, but (meth)acrylate copolymers are not limited to polymers composed only of (meth)acrylic acid and its esters, and may include structural units derived from monomers having polymerizable double bonds other than (meth)acrylic acid, etc.

[0037] (Meth)acrylate copolymers can undergo a crosslinking reaction with a curing agent described later due to structural units having a hydroxyl group or a carboxyl group. Such a crosslinked structure can improve the cohesive force of the adhesive after the adhesive is applied. Also, by adjusting the degree of crosslinking, in addition to the storage elastic modulus and loss elastic modulus, the 180° peel strength and tack with respect to a silicon wafer can also be adjusted.

[0038] Examples of the structural unit having an alkyl group include monomers having no functional group that undergoes a crosslinking reaction with a curing agent described later. The monomers constituting such a structural unit having a hydrocarbon group are not particularly limited, and examples include alkyl (meth)acrylates having a linear, branched, or cyclic alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an isobutyl group, an amyl group, an isoamyl group, a hexyl group, a heptyl group, a cyclohexyl group, a 2-ethylhexyl group, an octyl group, an isooctyl group, a nonyl group, an isononyl group, a decyl group, an isodecyl group, an undecyl group, a lauryl group, a tridecyl group, a tetradecyl group, a stearyl group, an octadecyl group, and a dodecyl group. These may be used alone or in combination of two or more.

[0039] Among these, the number of carbon atoms of the alkyl group is preferably 3 to 12, more preferably 4 to 10, and even more preferably 6 to 8. Further, the alkyl group is preferably branched. More specifically, 2-ethylhexyl acrylate is preferred. By using a structural unit having such an alkyl group, the melt resistance, chip holding property, and peel resistance from the ring frame of the adhesive layer during dicing are improved, and the pick-up property during pick-up also tends to be further improved.

[0040] The content of the structural unit having an alkyl group is preferably 70 to 97 mol%, more preferably 80 to 97 mol%, and even more preferably 90 to 97 mol% with respect to 100 mol% of all the structural units of the (meth)acrylate copolymer. By the content of the structural unit having an alkyl group being within the above range, the melt resistance, chip holding property, and peel resistance from the ring frame of the adhesive layer during dicing are improved, and the pick-up property during pick-up also tends to be further improved.

[0041] The monomer constituting the structural unit having a hydroxyl group is not particularly limited, and examples thereof include hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 1-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. These may be used alone or in combination of two or more.

[0042] Among these, the number of carbon atoms of the structural unit having a hydroxyl group is preferably 4 to 10, more preferably 4 to 8, and even more preferably 4 to 6. More specifically, 2-hydroxyethyl acrylate is preferred. By using such a structural unit having a hydroxyl group, the melt resistance, chip holding property, and peel resistance from the ring frame of the adhesive layer during dicing are improved, and the pick-up property during pick-up tends to be further improved.

[0043] The content of the structural unit having a hydroxyl group is preferably 1.0 to 30 mol%, more preferably 2.0 to 15 mol%, and even more preferably 3.0 to 10 mol% with respect to 100 mol% of all the structural units of the (meth)acrylate copolymer.

[0044] When the content of the structural unit having a hydroxyl group is 1.0 mol% or more, the number of crosslinks increases, the loss elastic modulus is further improved, and the minimum value M of the difference (G’-G”) 1 and M 2 tends to be further improved. Also, when the content of the structural unit having a hydroxyl group is 1.0 mol% or more, the remaining glue on the chip tends to be more suppressed. Further, when the content of the structural unit having a hydroxyl group is 30 mol% or less, the adhesive strength tends to be further improved. This is because an excessive increase in the crosslink density is suppressed, and a decrease in the adhesive strength due to the adhesive layer becoming too hard is suppressed.

[0045] The monomer constituting the structural unit having a carboxyl group is not particularly limited, and examples thereof include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. These may be used alone or in combination of two or more.

[0046] Among these, acrylic acid and methacrylic acid are preferred, and acrylic acid is more preferred. By using such a structural unit having a carboxyl group, the melt resistance, chip holding property, and peel resistance from the ring frame of the adhesive layer during dicing are improved, and the pick-up property during pick-up tends to be further improved.

[0047] The content of the structural unit having a carboxyl group is preferably 0.1 to 10 mol%, preferably 0.15 to 5.0 mol%, and preferably 0.2 to 2.0 mol% with respect to 100 mol% of all the structural units of the (meth)acrylate copolymer.

[0048] When the content of the structural unit having a carboxyl group is 0.1 mol% or more, the storage modulus is further improved, and the minimum value M of the difference (G’ - G”) 1 and M 2 tends to be further improved. Furthermore, the scraping up of the adhesive by the dicing blade is suppressed, the pick-up property is further improved, and the remaining glue on the chip tends to be more suppressed. Also, when the content of the structural unit having a carboxyl group is 10 mol% or less, the adhesive strength tends to be further improved. This is because an excessive increase in the crosslinking density is suppressed, and a decrease in the adhesive strength due to the adhesive layer becoming too hard is suppressed.

[0049] The monomers constituting the other structural units other than the above are not particularly limited. For example, acid anhydride monomers such as maleic anhydride and itaconic anhydride; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate, etc. can be mentioned.

[0050] (Hardener) The curing agent constituting the adhesive layer is not particularly limited, and examples thereof include isocyanate-based curing agents, epoxy-based curing agents, amine-based curing agents, etc., and these may be single substances or mixtures. Among these, an isocyanate compound is preferably used.

[0051] Such isocyanate compounds are not particularly limited, and examples thereof include aromatic diisocyanates such as tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane-modified tolylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, methylene bis(4-cyclohexyl isocyanate); aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate. These may be used alone or in combination of two or more.

[0052] Among these, the curing agent is preferably a polyfunctional isocyanate compound having two or more functional groups. By using such a curing agent, a plurality of (meth)acrylate copolymer can be crosslinked by the curing agent, and an adhesive layer having high cohesive strength can be obtained. In addition, the anchoring property between the substrate and the adhesive layer is further improved, and stable adhesive properties can be obtained. Furthermore, it becomes easier to adjust the loss elastic modulus and the minimum value M 1 and M 2 Young's modulus, etc. to the above range.

[0053] The content of the curing agent is preferably 1 to 20 parts by mass, more preferably 3 to 15 parts by mass, and still more preferably 5 to 10 parts by mass with respect to 100 parts by mass of the polymer. When the content of the curing agent is within the above range, an adhesive layer having high cohesive strength can be obtained. In addition, the anchoring property between the substrate and the adhesive layer is further improved, and stable adhesive properties can be obtained. Furthermore, it becomes easier to adjust the loss elastic modulus and the minimum value M 1 and M 2 Young's modulus, etc. to the above range.

[0054] (Other components) The adhesive layer can be added with an adhesion promoter, a crosslinking retarder, an antioxidant, etc. as needed.

[0055] The adhesion promoter is not particularly limited. For example, it includes petroleum resins, terpene resins, terpene phenol resins, aromatic modified terpene resins, coumarone-indene resins, natural resin rosin, modified rosin, glycerin ester rosin, pentaerythritol ester rosin, phenol resins, xylene resins, alicyclic petroleum resins, styrene resins, dicyclopentadiene resins, etc.

[0056] The crosslinking retarder is not particularly limited. For example, in an adhesive composition containing an isocyanate-based curing agent, it is a compound that can suppress excessive viscosity increase of the adhesive composition by blocking the isocyanate groups of the curing agent. Such crosslinking retarders are not particularly limited. For example, β-diketones such as acetylacetone, hexane-2,4-dione, heptane-2,4-dione, octane-2,4-dione; β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, butyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, stearyl acetoacetate; benzoylacetone, etc.

[0057] The antioxidant is not particularly limited. For example, it includes methylhydroquinone, hydroquinone, 2,2 - methylene - bis(4 - methyl - 6 - tertiary butylphenol), catechol, hydroquinone monomethyl ether, monotertiary butylhydroquinone, 2,5 - ditertiary butylhydroquinone, p - benzoquinone, 2,5 - diphenyl - p - benzoquinone, 2,5 - ditertiary butyl - p - benzoquinone, picric acid, citric acid, phenothiazine, tertiary butylcatechol, 2 - butyl - 4 - hydroxyanisole, 2,6 - ditertiary butyl - p - cresol, and 4 - [[4,6 - bis(octylthio)-1,3,5 - triazin - 2 - yl]amino]-2,6 - ditertiary butylphenol.

[0058] (Thickness) The thickness of the adhesive layer is usually 1 to 100 μm, preferably 2 to 50 μm, and more preferably 5 to 40 μm. By making the thickness of the adhesive layer 1 μm or more, sufficient adhesion to the die bonding film can be ensured, so it becomes easy to suppress the scattering of the semiconductor chips divided by expansion. On the other hand, when the thickness of the adhesive layer is 100 μm or less, the cost tends to be more suppressed.

[0059] (Base material) The material constituting the base material is not particularly limited. For example, polyvinyl chloride, polyethylene terephthalate, ethylene-vinyl acetate copolymer, ethylene-acrylic acid-acrylic acid ester film, ethylene-ethyl acrylate copolymer, polyethylene, polypropylene, propylene-based copolymer, ethylene-acrylic acid copolymer, and ionomer resins obtained by crosslinking ethylene-(meth)acrylic acid copolymer or ethylene-(meth)acrylic acid-(meth)acrylic acid ester copolymer with metal ions can be mentioned. The base material film may be a single one of these resins, a mixture of two or more kinds, a copolymer, or a laminate thereof.

[0060] The thickness of the above base material layer can be appropriately selected within a range that does not impair workability. The thickness of the base material layer is usually 10 to 500 μm, preferably 50 to 200 μm, and more preferably 70 to 150 μm. By adjusting the thickness of the base material layer within the above range, there are no practical problems and it is economically effective. When the base material layer is composed of a plurality of base material films, it is preferable to adjust so that the total thickness of the base material layer is within the above range.

[0061] The base material layer may be chemically or physically surface-treated as necessary to improve the adhesion to the adhesive layer. Examples of the above surface treatment include corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-voltage electric shock exposure, and ionization radiation treatment.

[0062] In one embodiment, it is preferable to adjust the thicknesses of the base material layer and the adhesive layer within the above ranges so that the thickness of the tape for semiconductor wafer processing is in the range of 60 to 250 μm. The thickness of the tape for semiconductor wafer processing is more preferably in the range of 70 to 200 μm, and even more preferably in the range of 70 to 150 μm.

[0063] (Protective film) The adhesive tape of the present embodiment may have a protective film laminated on the adhesive layer in order to protect the adhesive layer. Since the protective film is peeled off when the adhesive tape is used, a film having excellent peelability is preferable. The protective film is not particularly limited, and examples thereof include a film having a low surface energy made of a fluororesin, a film obtained by treating the surface of polyethylene terephthalate with a silicone-based release agent, and the like.

[0064] [Tape for semiconductor wafer processing] The tape for semiconductor wafer processing of the present embodiment includes the above adhesive tape and a die bonding film laminated on the adhesive layer of the adhesive tape. The die bonding film is not particularly limited, and commercially available products or the like can be used.

[0065] [Method for manufacturing adhesive tape] The method for manufacturing the adhesive tape is not particularly limited, and examples thereof include a method of forming an adhesive layer on a base material layer.

[0066] The base material layer of the adhesive tape of the present embodiment can be manufactured in accordance with well-known techniques. The means for forming the base material layer is not particularly limited, but the above various materials are mixed using conventional melt kneading or the like and various mixing devices (single-screw or twin-screw extruder, roll, Banbury mixer, various kneaders, etc.) so that the components are uniformly dispersed, and the mixture is formed into a base material by the T-die method, calendar method, or inflation method. Preferably, it is a method of forming a film using the T-die method with an extruder having good thickness accuracy.

[0067] The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present embodiment can be manufactured in accordance with well-known techniques. The means for forming the pressure-sensitive adhesive layer is not particularly limited. For example, the above various materials are dissolved in a solvent such as an organic solvent to form a varnish, which is then applied onto a protective film by means of a knife coating method, a roll coating method, a spray coating method, a gravure coating method, a bar coating method, a curtain coating method, or the like, and the solvent is removed to form the pressure-sensitive adhesive layer. By laminating this onto the base material layer, a pressure-sensitive adhesive tape is produced.

[0068] In the present embodiment, after forming the pressure-sensitive adhesive layer, an aging treatment may be performed. In the aging treatment, the formed pressure-sensitive adhesive layer is stored at a predetermined temperature. The temperature conditions are not particularly limited, but are preferably 30 to 50°C, more preferably 35 to 45°C. Also, the aging time is not particularly limited, but is preferably 24 to 150 hours, more preferably 48 to 100 hours.

[0069] By performing such an aging treatment, the adhesive strength and the dynamic viscoelastic properties of the pressure-sensitive adhesive layer change. For example, as the aging time progresses, the reaction between the polymer and the curing agent gradually proceeds, the adhesive strength decreases, and tends to stabilize at a predetermined value. Also, the dynamic viscoelastic properties can change with the aging time.

[0070] 〔Processing Method〕 The processing method of the present embodiment is a method having a laminating step of laminating the above pressure-sensitive adhesive tape and an adherend, a dicing step of dicing the adherend in a state where the pressure-sensitive adhesive tape and the adherend are laminated, and a pickup step of picking up the diced chips.

[0071] The method of dicing for the dicing step is not particularly limited, and a conventionally known method can be used. For example, by using a dicing device to rotate a dicing blade containing diamond abrasive grains at high speed, a silicon wafer can be cut into semiconductor chips.

[0072] The picking-up method is not particularly limited, and conventionally known methods can be used. For example, using an expanding device, the adhesive tape after ultraviolet irradiation is stretched in the plane direction, and the chips can be picked up by a picking-up device in a state where each chip is separated.

Example

[0073] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

[0074] (Example 1) 2-Ethylhexyl acrylate (96 mol%), 2-Hydroxyethyl acrylate (3.75 mol%), and Acrylic acid (0.25 mol%) were mixed, and copolymerized in ethyl acetate at 65 °C for 24 hours using an initiator (azobisisobutyronitrile) to obtain a solution containing acrylic polymer A.

[0075] Subsequently, 8.0 parts by mass of trimethylolpropane-modified tolylene diisocyanate curing agent (manufactured by Nippon Polyurethane Industry Co., Ltd.: Coronate L-45E) as curing agent A was added to the solution containing 100 parts by mass of acrylic polymer A obtained as described above to prepare a resin composition which is a general pressure-sensitive adhesive.

[0076] This resin composition was coated on the release-treated surface of a polyethylene terephthalate protective film which had been previously subjected to release treatment so that the thickness of the dried adhesive layer was 5 μm, dried at 100 °C for 1 minute, and then laminated with the corona-treated surface of an ionomer film (base film) of ethylene-methacrylic acid-acrylic acid ester copolymer whose surface to which the adhesive layer was to be laminated in advance had been subjected to corona treatment to transfer the adhesive to the base film. This was aged in an atmosphere at 40 °C for 72 hours to obtain an adhesive tape.

[0077] Further, the polyethylene terephthalate protective film was peeled off, and an epoxy-based die bonding film was laminated on the adhesive layer to obtain a tape for semiconductor wafer processing.

[0078] (Examples 2, 3 and Comparative Examples 1 - 4) A semiconductor wafer processing tape was produced in the same manner as in Example 1, except that the blending amount of trimethylolpropane - modified tolylene diisocyanate, which is Hardener A, was changed as shown in Table 1.

[0079] (Example 4) A solution containing acrylic polymer B obtained by mixing 96 mol% of 2 - ethylhexyl acrylate and 4 mol% of 2 - hydroxyethyl acrylate and copolymerizing them in ethyl acetate at 65°C for 24 hours using an initiator (azobisisobutyronitrile) was used, and a semiconductor wafer processing tape was produced in the same manner as in Example 1.

[0080] (Examples 5 - 6) A semiconductor wafer processing tape was produced in the same manner as in Example 4, except that hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd.: Coronate HX), which is Hardener B, was used instead of trimethylolpropane - modified tolylene diisocyanate.

[0081] For each sample of Examples 1 - 6 and Comparative Examples 1 - 4, evaluation tests were conducted as follows for storage modulus, loss modulus, Young's modulus, 180° peel adhesion to silicon wafer, probe tack, dicing, and pick - up. The obtained results are summarized in Table 1 below.

[0082] <Dynamic viscoelasticity measurement> The resin composition, which is a general pressure - sensitive adhesive prepared as described above, was applied to the release - treated surface of a polyethylene terephthalate film with release treatment, and dried at 100°C for 1 minute to obtain an adhesive layer. Then, the adhesive layers were overlapped so that the obtained adhesive layer had a thickness of 1 mm, and die - cut into a cylindrical shape with a diameter of 8 mm to obtain a sample.

[0083] Then, the sample was held in a thermo-hygrostat at a temperature of 23 °C (±2 °C) and a relative humidity of 50% (±5%) for 40 hours. Using the sample of the adhesive layer thus prepared, dynamic viscoelasticity measurement was performed by the torsional shear method using a viscoelasticity measuring device (MCR-301 manufactured by Anton Paar), and the storage modulus and loss modulus were obtained. The measurement conditions are shown below. (Measurement conditions) Mode: Shear mode Measurement point: 300 Oscillation angle γ: 0.05% Frequency f: 1 Hz Temperature: 23 to 150 °C Heating rate: 3 °C / min

[0084] <Young's modulus> The adhesive layer of the adhesive tape was cut out to a width of 1 cm, a length of 10 cm, and a thickness of 60 to 110 μm and used as a sample. The Young's modulus of the adhesive layer was measured with a universal tensile testing machine (Tensilon model number: RTG-1210 manufactured by ORIENTEC) in an environment of a temperature of 23 °C and a humidity of 50%. (Measurement conditions) Measurement mode: Tension Tensile speed: 5 mm / min Distance between chucks: 50 mm

[0085] <180° peel strength> The adhesive strength of the adhesive tape was measured in accordance with the adhesive strength measurement method of JIS Z0237 (2009) (Method 1: Test method for peeling the tape and sheet at 180° from a stainless steel test plate). Specifically, the 180° peel strength when peeling at 180° from the adherend (silicon wafer) whose surface was cleaned and pressure-bonded using a pressure-bonding device (roller mass: 2 kg) was measured with a universal tensile testing machine (Tensilon model number: RTG-1210 manufactured by ORIENTEC) in an environment of a temperature of 23 °C and a humidity of 50%. (Measurement conditions) Measurement mode: Tension Tensile speed: 300 mm / min Distance between chucks: 50 mm Measured sample width: 10 mm

[0086] <Tack> For the adhesive tape cut into 1 cm widths, measurements were taken at a temperature of 23°C using a probe tack tester (NS Probe Tack Tester, manufactured by Nichiban Co., Ltd., model number: TP-5820A / 24A). (Measurement conditions) Probe diameter: 5 mmφ Probe base material: Made of stainless steel, mirror finish by AA#400 polishing Weight: 19.6 ± 0.2 g (brass) Probe moving speed: 1.0 cm / second Dwell time: 0.1 second

[0087] <Dicing process> On the back surface of a silicon wafer with a diameter of 8 inches and a thickness of 0.1 mm, an adhesive tape was bonded using a tape mounter device equipped with a roller. The silicon wafer was diced into semiconductor chips of 0.49 mm × 0.3 mm using a dicing blade. The main setting conditions for dicing are as follows. (Setting conditions) Dicing device: DAD341 manufactured by DISCO Dicing blade: NBC-ZH205O-27HEEE manufactured by DISCO Dicing blade rotation speed: 40,000 rpm Dicing blade feed speed: 50 mm / second Cutting water temperature: 25°C Cutting water volume: 1.0 liter / minute

[0088] <Pickup process> After the dicing process, the semiconductor chips were picked up and peeled off from the adhesive tape. The main setting conditions for pickup are as follows. (Setting conditions) Pickup device: CAP-300II manufactured by Canon Machinery Needle pin shape: 250 μmR Needle pin lifting height: 0.5 mm Expansion amount: 8 mm Pushing-up speed: 10,000 μm / second

[0089] <Dicing property: Evaluation of the melt resistance of the adhesive layer> After the dicing process, the cutting surface by the dicing blade was confirmed by SEM, and the melt resistance of the adhesive layer was evaluated according to whether the boundary between the adhesive layer and the die bonding film could be confirmed on the cutting surface. Note that when the adhesive layer is melted by the frictional heat of the dicing blade, it becomes difficult to confirm the boundary between the adhesive layer and the die bonding film due to the melted adhesive layer. (Evaluation criteria) 〇 (Excellent): There is no melting in the adhesive layer, and the boundary between the adhesive layer and the die bonding film can be clearly confirmed. △ (Good): Partial melting is observed in the adhesive layer, but the boundary between the adhesive layer and the die bonding film can be confirmed. × (Unacceptable): The adhesive layer is melted, and the boundary between the adhesive layer and the die bonding film cannot be confirmed.

[0090] <During dicing: Evaluation of chip holding property> After the dicing process, among the total number of semiconductor chips after singulation, the ratio of the number of semiconductor chips that are not dropped such as chip skipping and are held by the adhesive tape was calculated, and the chip holding property was evaluated based on the following evaluation criteria. (Evaluation criteria) 〇 (Excellent): The ratio of the held semiconductor chips is 95% or more △ (Good): The ratio of the held semiconductor chips is 90% or more and less than 95% × (Unacceptable): The ratio of the held semiconductor chips is less than 90%

[0091] <Evaluation of peelability from the ring frame> After the dicing process, the peeling of the adhesive tape from the ring frame was visually observed, and the peelability from the ring frame was evaluated based on the following evaluation criteria. (Evaluation criteria) 〇 (Excellent): No peeling △(Good): There is partial peeling, but more than half is retained. ×(Not acceptable): More than half or the whole has peeled off.

[0092] <Pick-up property evaluation> The pick-up property was evaluated by calculating the ratio (pick-up yield) of the semiconductor chips that could actually be picked up among the semiconductor chips for which pick-up was attempted in the pick-up process, and based on the following evaluation criteria. (Evaluation criteria) 〇(Excellent): The pick-up yield is 95% or more. △(Good): The pick-up yield is 80% or more and less than 95%. ×(Not acceptable): The pick-up yield is less than 80%.

[0093]

Table 1

Industrial applicability

[0094] The adhesive tape of the present invention has industrial applicability as a tape for semiconductor wafer processing, particularly as an adhesive tape used in the dicing process.

Claims

1. A pressure-sensitive adhesive layer is provided on a substrate layer, In the temperature range of 23°C to 150°C, The loss modulus G″ of the pressure-sensitive adhesive layer is 1.0×10 2 Pa or more, 1.6×10 5 Pa or less, and The minimum value M of the difference (G'-G") between the storage modulus G' and the loss modulus G" of the pressure-sensitive adhesive layer at the same temperature 1 But 1.0 x 10 5 Pa or more, In the temperature range of 70°C to 110°C, The minimum value M of the difference (G'-G") between the storage modulus G' and the loss modulus G" at the same temperature 2 But 1.0 x 10 5 Pa or more, The 180° peel strength of the pressure-sensitive adhesive layer against a silicon wafer under a temperature condition of 23° C. is 0.03 N / 20 mm or more and 0.35 N / 20 mm or less. Dicing tape.

2. The Young's modulus of the pressure-sensitive adhesive layer is 0.5 MPa or more and 7.0 MPa or less. The dicing tape according to claim 1 .

3. The tack of the pressure-sensitive adhesive layer under a temperature condition of 23° C. is 0.03 N / 20 mm 2 Above 0.65N / 20mm 2 Below is the The dicing tape according to claim 1 or 2.

4. the pressure-sensitive adhesive layer comprises a (meth)acrylic acid ester copolymer, The (meth)acrylic acid ester copolymer has a linear, branched, or crosslinked chain structure. The dicing tape according to any one of claims 1 to 3.

5. In the (meth)acrylic acid ester-based copolymer, the content of structural units having a hydroxyl group is 1.0 mol % or more and 30 mol % or less, relative to 100 mol % of all structural units; The content of the structural unit having a carboxyl group is 0.1 mol % or more and 10 mol % or less with respect to 100 mol % of all structural units. The dicing tape according to claim 4.

6. The pressure-sensitive adhesive layer further comprises a curing agent. The dicing tape according to any one of claims 1 to 5.

7. The curing agent includes an isocyanate compound. The dicing tape according to claim 6.

8. The isocyanate compound includes a polyfunctional isocyanate compound having two or more functionalities. The dicing tape according to claim 7.

9. The dicing tape according to any one of claims 1 to 8, and a die bonding film laminated on the adhesive layer of the dicing tape. Tape for semiconductor wafer processing.

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