TW201945492A - Adhesive tape and production method for semiconductor device - Google Patents

Abstract

An object of the present invention is to provide an adhesive tape capable of stably holding a wafer or the like even when dry polishing is performed after a so-called pre-dicing method.
The solution of the present invention is to provide an adhesive tape for grinding the back surface of a semiconductor wafer having grooves formed on the surface of the semiconductor wafer, and singulating the semiconductor wafer into semiconductor wafers by the grinding. Then, in the step of performing dry polishing, the adhesive tape to be used on the surface of the semiconductor wafer includes a substrate and an adhesive layer provided on one side thereof, and a tensile storage mold of the aforementioned substrate at 60 ° C. The number is above 250 Mpa.

Description

Adhesive tape and manufacturing method of semiconductor device

The present invention relates to an adhesive tape. More specifically, the present invention relates to a method for manufacturing a semiconductor device when a semiconductor wafer is manufactured by dry polishing after wafering the semiconductor wafer by a so-called predicing method. A temporarily fixed adhesive tape such as a wafer or a wafer, and a method for manufacturing a semiconductor device using the adhesive tape.

In the progress of miniaturization and multifunctionalization of various electronic devices, the semiconductor chips mounted thereon are also required to be miniaturized and thinned. In order to reduce the thickness of a wafer, the back surface of a semiconductor wafer is usually ground to adjust the thickness. In addition, there is also a technique called a pre-cut method, in which a groove having a predetermined depth is formed from a surface side of a wafer, and then is ground from the back side of the wafer. The wafer is singulated and a wafer is obtained. Since the back surface grinding of the wafer and the singulation of the wafer can be performed simultaneously by the pre-cutting method, a thin wafer can be manufactured efficiently.

Previously, when the back surface of a semiconductor wafer was ground and wafers were manufactured using a pre-cut method, an adhesive tape called a back-side abrasive sheet was usually attached to the surface of the wafer to protect circuits on the surface of the wafer. The semiconductor wafer and the semiconductor wafer are fixed.

Examples of the back-side polishing sheet used in the pre-cut method include an adhesive tape including a substrate and an adhesive layer provided on one surface of the substrate. As an example of such an adhesive tape, Japanese Patent Application Laid-Open No. 2015-185691 (Patent Document 1) proposes an adhesive tape for semiconductor wafer processing in which a radiation-curable adhesive layer is provided on a base film. Patent Document 1 discloses, as a base film, a base material obtained by laminating two different materials selected from at least two types of polyethylene terephthalate, polypropylene, and an ethylene-vinyl acetate copolymer. As a specific example of the film, a substrate film composed of three layers of polyethylene / polyethylene terephthalate / polyethylene is disclosed.

When the wafer is singulated using the pre-cut method as described above, in order to remove the heat generated during grinding, grinding debris, and the like during back grinding, it is performed while supplying water to the grinding surface. Back grinding. However, in such conventional back surface grinding, grinding marks remain on the back surface of the wafer, and it is known that this is the main reason for damaging the bending strength of the wafer. In particular, as a result of the thinness and miniaturization of the wafer, it is considered that the wafer is easily damaged and the flexural strength is low.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2015-185691

[Questions to be Solved by the Invention]

In order to remove the above-mentioned grinding marks (hereinafter referred to as "damaged parts"), it has been studied to grind the back surface using water, and finally dry the surface by dry polishing without using water. The damaged portion is removed, and the bending strength of the wafer is improved. The dry polishing refers to a step of polishing with a polishing buff without using slurry such as water and abrasive particles.

However, unlike the back-grinding step, water is not used during dry polishing, so the heat generated during polishing cannot be removed by water, causing the wafer to contain heat. The heat of the wafer is transferred to the adhesive tape attached to the wafer. As a result, the temperature of the adhesive tape may be 60 ° C or higher during dry polishing.

Since the base material of the adhesive tape is made of a resin component, it is easily deformed by heat. During dry polishing, if the base material of the adhesive tape is deformed by heat, the fixing of the adhesive tape at the ends becomes insufficient, and the wafer on the adhesive tape cannot be held sufficiently, causing the wafer to peel off and scatter. Such scattering of the wafers not only causes a decrease in yield, but also causes the scattered wafers to contact other wafers to damage other wafers or cause damage to the grinding device, and therefore causes a poor handling in the next step.

The present invention has been made in view of such a situation, and an object thereof is to provide an adhesive tape capable of stably holding a wafer or the like even when dry polishing is performed after a so-called pre-cut method.
[Means to solve the problem]

The aspect of the present invention is,
[1] An adhesive tape for grinding a back surface of a semiconductor wafer having grooves formed on a surface of the semiconductor wafer, and singulating the semiconductor wafer into semiconductor wafers by the grinding, and then performing In the step of dry polishing, the adhesive tape used on the surface of the semiconductor wafer includes a substrate and an adhesive layer provided on one side thereof, and the tensile storage modulus of the substrate at 60 ° C is 250 MPa the above.

[2] A method for manufacturing a semiconductor device, comprising the steps of: forming a trench from a surface side of a semiconductor wafer; and including a substrate and an adhesive layer provided on one side thereof at a temperature of 60 ° C of the substrate. The step of stretching an adhesive tape with a storage modulus of 250 MPa or more and attaching it to the surface of the semiconductor wafer; grinding the semiconductor wafer with the adhesive tape and grooves formed on the surface from the back side, and A step of removing the bottom of the trench to form a wafer into a plurality of wafers; a step of drying a semiconductor wafer after the wafer is sliced into a semiconductor wafer; and a step of peeling the wafer from the adhesive tape.
[Inventive effect]

The adhesive tape of the present invention can stably hold a semiconductor wafer even when the temperature of the adhesive tape rises due to heat during dry polishing. Therefore, even if a pre-cut method including a dry polishing step is performed, a semiconductor wafer can be manufactured with a high yield.

Forms used to implement the invention

Hereinafter, the adhesive tape of this invention is demonstrated concretely. First, the main terms used in this specification will be described.

In the present specification, for example, the term "(meth) acrylate" is used to mean both "acrylate" and "methacrylate", and the same applies to other similar terms.

The so-called adhesive tape means a laminated body including a base material and an adhesive layer provided on one side thereof, and may include other constituent layers other than these. For example, a primer layer may be formed on the surface of the substrate on the side of the adhesive layer for the purpose of improving the adhesion between the surface of the substrate and the adhesive layer and preventing the migration of low molecular weight components. In addition, in order to protect the adhesive layer until use, a release sheet may be laminated on the surface of the adhesive layer. The base material may be a single layer or a plurality of layers including a functional layer such as a buffer layer. The same applies to the adhesive layer.

The "surface" of a semiconductor wafer refers to a surface on which a circuit is formed, and the "back surface" refers to a surface on which a circuit is not formed.
The so-called singulation of a semiconductor wafer refers to dividing the semiconductor wafer according to each circuit to obtain a semiconductor wafer.

The so-called dry polishing refers to a step of grinding without using a slurry containing water, abrasive particles, and the like, and using a polishing wheel. In addition, in this specification, it may be described as a "dry polishing step."

As the grinding and polishing wheels used for dry polishing, various general-purpose grinding and polishing wheels can be used. As commercially available products, the grinding wheels "Gettering DP" and "DP08 SERIES" from DISCO Corporation can be used, but they are not limited to these. . The damaged portion of the wafer, that is, the grinding mark is removed by dry polishing.

The so-called pre-cut method refers to a method in which a groove having a predetermined depth is formed from a surface side of a wafer, and then the wafer is ground from the back side of the wafer, and the wafer is singulated by grinding.

The so-called back-grinding tape refers to an adhesive tape used to protect the circuit surface of a wafer when the back surface of a semiconductor wafer is ground. In particular, in this specification, it refers to an adhesive tape that can be suitably used in a pre-cut method.

(1. Adhesive tape)
The adhesive tape of the present invention can be used as the above-mentioned back-grinding tape in the dry polishing step. The adhesive tape of the present invention includes a substrate and an adhesive layer provided on one side thereof. Hereinafter, constituent elements of the adhesive tape will be described in detail.

(1.1. Substrate)
As a base material of the adhesive tape of this embodiment, various resin films used as a base material of a back-grinding tape can be used.

Hereinafter, an example of the base material used in the present invention will be described in detail, but these are described only for easily obtaining the base material, and should not be interpreted in any limiting manner.

(1.2. Physical properties of the substrate)
In this embodiment, the tensile storage modulus (E ′ ₆₀ ) of the substrate at 60 ° C. is preferably 250 MPa or more. The tensile storage modulus (E ') is one of the indicators of the ease of deformation (hardness) of the substrate. When the tensile storage modulus (E _'60 ) of the substrate at 60 ° C is within the above-mentioned range, it is possible to prevent the wafer caused by thermal deformation of the substrate from peeling from the adhesive tape, and it is possible to prevent the processing step, especially Deformation of the substrate due to stress during dry polishing. In addition, it is possible to appropriately maintain the cushioning performance against stress during back surface grinding and dry polishing.

In addition, the semiconductor wafer to which the adhesive tape is attached is placed on the adsorption machine through the adhesive tape during back grinding and dry polishing, and the tensile storage modulus (E _'60 ) of the substrate is set at In the above range, the adhesion between the adhesive tape and the suction table is improved, and vibrations during back surface grinding and dry polishing can be suppressed. In addition, it is easy to peel the adhesive tape from the adsorption machine after the back surface is ground and after the dry polishing.

E _'60 to preferably 270 MPa or more, more preferably of at least 300 MPa. On the other hand, E _'60 to 4000 MPa or less is preferable, and is more preferably 110 0MPa less.

Therefore, in this embodiment, by controlling the tensile storage modulus of the substrate at 60 ° C within the above-mentioned range, even when the adhesive layer is heated during dry polishing, the wafer can be effectively suppressed. Flying away.

The tensile storage modulus of the substrate is the same as the loss tangent of the adhesive layer and the shear storage modulus, and can be measured by a known method. For example, a sample of a predetermined size can be made of a material composed of the same material as the sheet or film constituting the substrate, and a dynamic viscoelasticity measuring device can be used to apply strain to the sample at a predetermined temperature in a predetermined temperature range to measure the mold. The tensile storage modulus was calculated from the measured modulus.

From the viewpoints of material, physical properties, thickness, and the like, the tensile storage modulus E ′ of the substrate can be controlled by appropriately selecting a film constituting the substrate. For example, as a constituent film, it is possible to control the tensile storage modulus to a predetermined range by selecting a film having a relatively high Tg, and performing an annealing treatment during film formation of the substrate.

(1.3. Specific examples of substrates)
Hereinafter, specific examples of the substrate will be described, but these are described only for easily obtaining the substrate, and should not be interpreted in any limiting manner.

The substrate of the present invention may be, for example, a relatively hard resin film. The base material of the present invention may be a laminate formed by laminating a buffer layer made of a relatively soft resin film on one or both sides of a relatively hard resin film.

The thickness of the substrate is not particularly limited, but is preferably 500 μm or less, more preferably 15 to 350 μm, and even more preferably 20 to 160 μm. By setting the thickness of the substrate to 500 μm or less, it is easy to control the peeling force of the adhesive tape. Moreover, by setting it as 15 micrometers or more, a base material will become easy to function as a support body of an adhesive tape.

As the material of the substrate, various resin films can be used. Here, examples of the substrate having a tensile storage modulus of 250 MPa or more include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and Polyesters such as aromatic polyesters, polyamines, polycarbonates, polyacetals, modified polyphenylene ethers, polyphenylene sulfide, polyfluorene, polyetherketone, biaxially-stretched polypropylene and other resins membrane.

Among these resin films, it is preferable to include one or more films selected from a polyester film, a polyamide film, and a biaxially stretched polypropylene film, and it is more preferable to include a polyester film to include polyterephthalic acid. An ethylene glycol film is further preferred.

Moreover, as long as the effect of this invention is not impaired, a base material may contain a plasticizer, a slip agent, an infrared absorber, an ultraviolet absorber, a filler, a coloring agent, an antistatic agent, an antioxidant, a catalyst, etc. In addition, the substrate is transmissive to the energy ray irradiated when the adhesive layer is cured.

Further, in order to improve the adhesion with at least one of the buffer layer and the adhesive layer, a subsequent treatment such as a corona treatment may be performed on at least one surface of the substrate. In addition, the substrate may include the above-mentioned resin film and an easy-adhesive layer (primer layer) covering at least one surface of the resin film.

The composition for forming an easy-adhesive layer for forming an easy-adhesive layer is not particularly limited, and examples thereof include polyester resins, urethane-based resins, polyester urethane-based resins, and acrylic resins. The composition. The composition for forming an easy-to-adhesive layer may contain a cross-linking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, a rust inhibitor, a pigment, a dye, and the like, as necessary.

The thickness of the easy-adhesion layer is preferably 0.01 to 10 μm, and more preferably 0.03 to 5 μm. In addition, the thickness of the easy-adhesion layer is smaller than the thickness of the base material, and the easy-adhesion layer is a softer material, so the influence on the tensile storage modulus is small. The tensile storage modulus is substantially the same as the tensile storage modulus of the resin film.

(1.4.Buffer layer)
A buffer layer may be provided on one or both sides of the substrate. The buffer layer is made of a relatively soft resin film, which can mitigate vibrations caused by grinding of the semiconductor wafer, and prevent cracks and defects from being generated in the semiconductor wafer. In addition, the semiconductor wafer attached to the adhesive tape is disposed on the adsorption machine when the back surface is ground. By providing a buffer layer, the adhesive tape can be easily and appropriately held on the adsorption machine.

The thickness of the buffer layer is preferably 8 to 80 μm, and more preferably 10 to 60 μm.

Buffer layer: polypropylene film, ethylene-vinyl acetate copolymer film, ionic polymer resin film, ethylene‧ (meth) acrylic copolymer film, ethylene‧ (meth) acrylate copolymer film, LDPE film, LLDPE The film is better. It may also be a layer formed of a composition for forming a buffer layer containing an energy ray polymerizable compound. The substrate can be bonded to the film to obtain a substrate having a buffer layer.

(1.5. Adhesive layer)
Hereinafter, an example of the adhesive layer used in the present invention will be described in detail in the order of physical properties and composition. However, these are only described for the ease of manufacturing or obtaining the adhesive layer, and should not be interpreted in any limiting manner.

(1.6. Physical properties of the adhesive layer)
The adhesive layer is not particularly limited as long as it is configured so as to exhibit the performance of the adhesive tape. In this embodiment, as described above, the temperature of the adhesive tape may be 60 ° C or higher during dry polishing.

Accordingly, in the present embodiment, it is preferably in the loss of the adhesive layer 60 ℃ tangent (tanδ ₆₀₎ is 0.40 or less, and preferably a shear storage modulus of the adhesive layer of 60 deg.] C (G _'60 ) Is 3.0 × 10 ⁴ pa or more.

The loss tangent (tanδ) is defined by "loss modulus / storage modulus", and is a value measured by using a dynamic viscoelasticity measuring device and responding to stresses such as tensile stress and torsional stress applied to an object. . With the loss tangent (tan δ ₆₀ ) of the adhesive layer at 60 ° C within the above range, even in the processing step, especially the dry polishing step, when the adhesive layer is stressed, the adhesive layer deformation can be suppressed, and the wafer Since the alignment property can be maintained, there is a tendency that wafer scattering can be suppressed.

The tan δ _{60 is} more preferably 0.05 or more, and still more preferably 0.10 or more. On the other hand, tan δ ₆₀ is more preferably 0.37 or less.

The shear storage modulus (G ') is one of the indicators of the ease of deformation (hardness) of the adhesive layer. With the shear storage modulus (G _'60 ) of the adhesive layer at 60 ° C within the above range, even in the processing step, especially the dry polishing step, when the adhesive layer is stressed, the wafer and the adhesive layer The adhesiveness is also good, and the holding force of the adhesive layer on the wafer can be maintained, so there is a tendency that the scattering of the wafer can be suppressed.

And, G _'60, at least 3.5 × 10 ⁴ pa is more preferably, 3.7 × 10 ⁴ pa above are further preferred. On the other hand G _'60, at 5.0 × 10 ⁵ pa or less is more preferred, at 1.0 × 10 ⁵ pa or less is further preferred.

Therefore, in this embodiment, by controlling both the loss tangent and the shear storage modulus of the adhesive layer at 60 ° C within the above-mentioned range, even if the adhesive layer is heated during dry polishing, it can be further improved. The effect of effectively suppressing the scattering of the wafer is improved.

The loss tangent of the adhesive layer and the shear storage modulus can be measured by a conventional method. For example, the adhesive layer can be made into a sample of a predetermined size, and a dynamic viscoelasticity measuring device can be used to apply strain to the sample at a predetermined temperature in a predetermined temperature range, thereby measuring the modulus, and calculating the loss tangent and Shear storage modulus.

The above-mentioned loss tangent and shear storage modulus mean the physical properties of the uncured adhesive layer before being attached to the semiconductor wafer or the semiconductor wafer at 60 ° C. When the adhesive layer is formed of an energy ray-curable adhesive, it refers to the physical properties of the adhesive layer before energy ray curing at 60 ° C.

The loss tangent and shear storage modulus can be changed by, for example, adjusting the composition of the adhesive composition constituting the adhesive layer.

The thickness of the adhesive layer is preferably less than 200 μm, more preferably 5 to 80 μm, and even more preferably 10 to 70 μm. When the adhesive layer is thinned in this way, the proportion of the portion with low rigidity can be reduced in the adhesive tape, so it is easy to further prevent the semiconductor wafer from being damaged during the back surface grinding.

(1.7. Composition of Adhesive Layer)
The composition of the adhesive layer is not particularly limited. In order to achieve the above-mentioned physical properties, the adhesive layer in this embodiment includes, for example, an acrylic adhesive, a urethane adhesive, a rubber adhesive, and a silicone adhesive. It is preferable that it is composed of an acrylic adhesive.

The adhesive layer is preferably formed of an energy ray-curable adhesive. Since the adhesive layer is formed of an energy ray-curable adhesive, the energy loss tangent and the shear storage modulus are set to the above ranges before curing with energy ray irradiation, and the peeling force can be easily changed after curing. 1000mN / 50mm or less.

Hereinafter, specific examples of the adhesive are described in detail, but these are non-limiting examples, and the adhesive layer of the present invention should not be construed as being limited to these.

As the energy ray-curable adhesive, for example, energy ray-curable properties of an adhesive resin containing non-energy-ray-curable adhesive (also referred to as "adhesive resin I") and an energy-ray-curable compound other than the adhesive resin Adhesive composition (hereinafter also referred to as "X-type adhesive composition"). In addition, as the energy-ray-curable adhesive, an energy-ray-curable adhesive resin (hereinafter also referred to as "adhesion") containing an unsaturated group introduced into a side chain of a non-energy-ray-curable adhesive resin may be used. Adhesive composition ("Resin II") as a main component and containing no energy ray-curable compound other than an adhesive resin (hereinafter also referred to as "Y-type adhesive composition").

In addition, as the energy ray-curable adhesive, it is also possible to use a combination of X-type and Y-type, that is, in addition to energy-ray-curable adhesive resin II, energy-ray-curable compounds other than adhesive resins are also included. Energy ray-curable adhesive composition (hereinafter also referred to as "XY-type adhesive composition").

Among these, it is preferable to use an XY-type adhesive composition. By using an XY type material, it has sufficient adhesive properties before curing, and on the other hand, it is possible to sufficiently reduce the peeling force to the semiconductor wafer after curing.

However, the adhesive may be formed of a non-energy-ray-curable adhesive composition that does not harden even when irradiated with energy rays. The non-energy-ray-curable adhesive composition is an adhesive composition containing at least non-energy-ray-curable adhesive resin I and not containing the above-mentioned energy-ray-curable adhesive resin II and energy-ray-curable compound.

In the following description, "adhesive resin" is used as a term meaning one or both of the above-mentioned adhesive resin I and adhesive resin II. Specific examples of the adhesive resin include acrylic resins, urethane resins, rubber resins, and silicone resins, and acrylic resins are preferred.

(1.7.1. Acrylic resin)
Hereinafter, as the adhesive resin, an acrylic adhesive using an acrylic resin will be described in more detail.

As the acrylic resin, an acrylic polymer (a) can be used. The acrylic polymer (a) is obtained by polymerizing a monomer containing at least an alkyl (meth) acrylate, and contains a structural unit derived from the alkyl (meth) acrylate. Examples of the alkyl (meth) acrylate include those having 1 to 20 carbon atoms in the alkyl group, and the alkyl group may be linear or branched. Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, N-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, (meth) ) Decyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, and the like. The alkyl (meth) acrylate can be used alone or in combination of two or more.

From the viewpoint of improving the adhesive force of the adhesive layer, the acrylic polymer (a) preferably has a structural unit containing an alkyl (meth) acrylate having 4 or more carbon atoms derived from an alkyl group. The carbon number of the alkyl (meth) acrylate is preferably 4 to 12, and more preferably 4 to 6. The alkyl (meth) acrylate having 4 or more carbon atoms is preferably an alkyl acrylate.

In the acrylic polymer (a), the content ratio of the (meth) acrylic acid alkyl ester having 4 or more carbon atoms in the alkyl group is relative to the total amount of monomers constituting the acrylic polymer (a) (hereinafter also simply referred to as " The total amount of monomers ") is preferably 40 to 98% by mass, more preferably 45 to 95% by mass, and even more preferably 50 to 90% by mass.

The acrylic polymer (a) contains an alkyl group-derived alkyl group in order to adjust the modulus and adhesion characteristics of the adhesive layer in addition to the structural unit derived from an alkyl (meth) acrylate having 4 or more carbon atoms derived from the alkyl group. The copolymer of the structural unit of the alkyl (meth) acrylate having 1 to 3 carbon atoms is preferred; and the alkyl (meth) acrylate having the carbon number of 1 or 2 is Preferably, methyl (meth) acrylate is more preferred, and methyl methacrylate is most preferred. In the acrylic polymer (a), the (meth) acrylic acid alkyl ester having 1 to 3 carbon atoms in the alkyl group is preferably 1 to 30% by mass and more preferably 3 to 26% by mass relative to the total amount of monomers. %, More preferably 6 to 22% by mass.

The acrylic polymer (a) preferably has a structural unit derived from a functional group-containing monomer in addition to the structural unit derived from the alkyl (meth) acrylate. Examples of the functional group of the functional group-containing monomer include a hydroxyl group, a carboxyl group, an amine group, and an epoxy group. The functional group-containing monomer can react with a cross-linking agent to be described later and become a starting point for crosslinking, or react with an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the acrylic polymer (a).

Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amine group-containing monomer, and an epoxy group-containing monomer. These monomers can be used individually or in combination of 2 or more types. Among these, a hydroxyl-containing monomer and a carboxyl-containing monomer are preferred, and a hydroxyl-containing monomer is more preferred.

Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like; hydroxyalkyl (meth) acrylate; vinyl alcohol, allyl alcohol Unsaturated alcohols and so on.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; fumaric acid, itaconic acid, maleic acid, and citraconic acid. And other ethylenically unsaturated dicarboxylic acids and their anhydrides, 2-carboxyethyl methacrylate, and the like.

The content ratio of the functional group monomer is preferably 1 to 35% by mass, more preferably 3 to 32% by mass, and still more preferably 6 to 30% by mass relative to the total amount of monomers constituting the acrylic polymer (a). %.

In addition, the acrylic polymer (a) may contain, in addition to the above, polymers derived from styrene, α-methylstyrene, vinyl toluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide. A structural unit of a monomer copolymerized with the acrylic monomer.

The acrylic polymer (a) can be used as a non-energy-ray-curable adhesive resin I (acrylic resin). Examples of the energy ray-curable acrylic resin include a compound having a photopolymerizable unsaturated group (also referred to as an unsaturated group-containing compound) and a functional group of the acrylic polymer (a). Into something.

The unsaturated group-containing compound is a compound having both a substituent capable of bonding to a functional group of the acrylic polymer (a) and a photopolymerizable unsaturated group. Examples of the photopolymerizable unsaturated group include a (meth) acrylfluorenyl group, a vinyl group, an allyl group, and a vinyl benzyl group, and a (meth) acrylfluorenyl group is preferred.

Moreover, as a substituent which an unsaturated group containing compound can bond with a functional group, an isocyanate group, a glycidyl group, etc. are mentioned. Therefore, examples of the unsaturated group-containing compound include (meth) acrylfluorenyl ethyl isocyanate, (meth) acrylfluorenyl isocyanate, and propylene oxide (meth) acrylate.

The unsaturated group-containing compound is preferably reacted with a part of the functional group of the acrylic polymer (a). Specifically, the unsaturated group-containing compound and the acrylic polymer (a) are preferably reacted. The reaction is performed at 50 to 98 mole% of the functional group, and more preferably, it is reacted at 55 to 93 mole%. As described above, in the energy ray-curable acrylic resin, a part of the functional groups does not react with the unsaturated group-containing compound and remains, and therefore is easily crosslinked by a crosslinking agent.

The weight average molecular weight (Mw) of the acrylic resin is preferably 300,000 to 1.6 million, more preferably 400,000 to 1.4 million, and even more preferably 500,000 to 1.2 million.

(1.7.2. Energy ray hardening compound)
The energy ray-curable compound contained in the X-type or XY-type adhesive composition is preferably a monomer or oligomer having an unsaturated group in the molecule and capable of polymerizing and hardening by energy ray irradiation.

Examples of such an energy ray-curable compound include trimethylolpropane tri (meth) acrylate, neopentyltetraol (meth) acrylate, neopentyltetraol tetra (meth) acrylate, and Polypentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol (meth) acrylate, etc. Polymers, oligomers such as urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, epoxy (meth) acrylate, and the like.

Among these, a urethane (meth) acrylate oligomer is preferable from the viewpoint that the molecular weight is high and the modulus of the adhesive layer is not easily reduced. The molecular weight (weight average molecular weight in the case of an oligomer) of the energy ray-curable compound is preferably 100 to 12,000, more preferably 200 to 10,000, still more preferably 400 to 8000, and particularly preferably 600 to 6000.

The content of the energy ray-curable compound in the X-type adhesive composition is preferably 40 to 200 parts by mass, more preferably 50 to 150 parts by mass, and still more preferably 60 to 100 parts by mass of the adhesive resin. 90 parts by mass.

On the other hand, the content of the energy ray-curable compound in the XY-type adhesive composition is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and more preferably 100 parts by mass of the adhesive resin. It is preferably 3 to 15 parts by mass. In the XY-type adhesive composition, since the adhesive resin is energy ray-curable, even if the content of the energy ray-curable compound is small, the peeling force can be sufficiently reduced after the energy ray irradiation.

(1.7.3. Crosslinking agent)
The adhesive composition preferably further contains a crosslinking agent. The cross-linking agent is, for example, a product that reacts a functional group derived from a functional group monomer that the adhesive resin has to cross-link the adhesive resins. Examples of the cross-linking agent include, for example, isocyanate-based cross-linking agents such as toluene diisocyanate, hexamethylene diisocyanate, and the like, and ethylene glycol glycidyl ether) and other epoxy-based crosslinking agents; nitrogen such as hexa [1- (2-methyl) -aziridinyl] triphosphotriazine (hexa [1- (2-methyl) -aziridinyl] triphosphatriazine) Aziridine-based cross-linking agents; chelate-based cross-linking agents such as aluminum chelates and the like. These crosslinking agents may be used alone or in combination of two or more.

Among these, an isocyanate-based crosslinking agent is preferred from the viewpoints of improving cohesion and adhesion, and from the viewpoint of easiness of acquisition.

From the viewpoint of promoting the crosslinking reaction, the blending amount of the crosslinking agent is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and still more preferably 0.05 to 100 parts by mass of the adhesive resin. 4 parts by mass.

(1.7.4. Photopolymerization initiator)
When the adhesive composition is energy ray-curable, the adhesive composition preferably further contains a photopolymerization initiator. By containing a photopolymerization initiator, even if it is a low energy energy ray, such as an ultraviolet-ray, the hardening reaction of an adhesive composition can fully advance.

Examples of the photopolymerization initiator include a benzoin compound, an acetophenone compound, an acylphosphine oxide compound, a titanocene compound, and 9-oxygen. sulfur (thioxanthone) compounds, peroxide compounds, and photosensitizers such as amines and quinones. More specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2 -Methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, Tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis (2, 4,6-trimethylbenzyl) phenylphosphine oxide (bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide) and the like.

These photopolymerization initiators may be used alone or in combination of two or more. The blending amount of the photopolymerization initiator relative to 100 parts by mass of the adhesive resin is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and still more preferably 0.05 to 5 parts by mass.

(1.7.5. Other additives)
The adhesive composition may contain other additives as long as the effect of the present invention is not impaired. Examples of the other additives include antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, and dyes. When blending these additives, the blending amount of the additives is preferably 0.01 to 6 parts by mass relative to 100 parts by mass of the adhesive resin.

In addition, from the viewpoint of improving the applicability to a substrate, a buffer layer, a release sheet, and the like, the adhesive composition may be further diluted with an organic solvent to obtain a solution of the adhesive composition.

Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. Wait.

In addition, as the organic solvent, an organic solvent used in the synthesis of the adhesive resin may be directly used, or a solution of the adhesive composition may be uniformly applied, and other than the organic solvent used in the synthesis may be added. One or more organic solvents.

(1.8. Release sheet)
A release sheet may be attached to the surface of the adhesive tape. Specifically, a release sheet is stuck on the surface of the adhesive layer of an adhesive tape. When the release sheet is attached to the surface of the adhesive layer and transported, the adhesive layer can be protected during storage. The release sheet is attached to the adhesive tape in a peelable manner, and is removed from the adhesive tape before the adhesive tape is used (that is, before the wafer back surface is ground).

The release sheet is a release sheet that has been subjected to a release treatment on at least one side, and specifically includes a release sheet obtained by applying a release agent to the surface of a substrate for a release sheet.

As the base material for the release sheet, a resin film is preferable. Examples of the resin constituting the resin film include polyethylene terephthalate resin, polybutylene terephthalate resin, and polynaphthalene. Polyester resin films such as ethylene formate resin, polyolefin resins such as polypropylene resin, polyethylene resin, and the like. Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, and alkyd. Resin, fluorine resin, etc.

The thickness of the release sheet is not particularly limited, but is preferably 10 to 200 μm, and more preferably 20 to 150 μm.

(2. Manufacturing method of adhesive tape)
There is no restriction | limiting in particular as a manufacturing method of the adhesive tape of this invention, It can manufacture using a well-known method.

For example, a pressure-sensitive adhesive layer provided on a release sheet can be bonded to one side of a substrate, and an adhesive tape having a release sheet attached to the surface of the pressure-sensitive adhesive layer can be manufactured. In addition, by laminating the buffer layer provided on the release sheet to the substrate and removing the release sheet, a laminated body of the buffer layer and the substrate can be obtained. In addition, the adhesive layer provided on the release sheet is bonded to the base material side of the laminate, and an adhesive tape having a release sheet attached to the surface of the adhesive layer can be manufactured. When the buffer layer is provided on both sides of the substrate, an adhesive layer can be formed on the buffer layer. The release sheet attached to the surface of the adhesive layer may be appropriately peeled off and removed before use of the adhesive tape.

As a method for forming an adhesive layer on a release sheet, an adhesive composition can be directly applied to the release sheet using a known coating method, and the coating film can be heated and dried to volatilize the solvent to form an adhesive layer. . Examples of the coating method include a spin coating method, a spray coating method, a bar coating method, a doctor blade coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method. Similarly, the adhesive composition may be directly coated on one side of the substrate or on the buffer layer to form an adhesive layer.

(3. Manufacturing method of semiconductor device)
The adhesive tape of the present invention can be particularly suitably used when the pre-cutting method is applied to the surface of a semiconductor wafer, the back surface of the wafer is ground, and then dry polishing is performed. As a non-limiting use example of the adhesive tape, a method for manufacturing a semiconductor device will be described in more detail below.

Specifically, the method for manufacturing a semiconductor device includes at least the following steps 1 to 4.
Step 1: a step of forming a trench from the surface side of the semiconductor wafer;
Step 2: the step of attaching the above-mentioned adhesive tape to the surface of the semiconductor wafer;
Step 3: The semiconductor wafer with the adhesive tape on the surface and the groove formed is ground from the back side, and the bottom of the groove is removed to form a wafer into a plurality of wafers. A step of dry polishing the wafer; and step 4: a step of peeling the adhesive tape from the singulated semiconductor wafer (ie, a plurality of semiconductor wafers).

Hereinafter, each step of the manufacturing method of the said semiconductor device is demonstrated in detail.

(3.1. Step 1)
In step 1, a trench is formed from the semiconductor wafer surface side. The trench formed in this step is a trench having a depth shallower than the thickness of the semiconductor wafer. The trench can be formed by dicing using a conventional wafer dicing device or the like. In addition, the semiconductor wafer is divided into a plurality of semiconductor wafers along the trench by removing the bottom of the trench in step 3 described later.

The semiconductor wafer used in this manufacturing method may be a silicon wafer, but may also be a wafer such as gallium arsenic, a glass wafer, or a sapphire wafer. The thickness before grinding of the semiconductor wafer is not particularly limited, but is usually about 500 to 1000 μm. Moreover, a semiconductor wafer usually has a circuit formed on its surface. Forming a circuit on a wafer surface can be performed using various methods including a conventionally widely used method such as an etching method, a lift-off method, and a blade method.

(3.2. Step 2)
In step 2, the adhesive tape of the present invention is adhered to the surface of the semiconductor wafer having the groove formed through the adhesive layer.

The semiconductor wafer to which the adhesive tape is attached and the grooves are formed is placed on the adsorption machine and held by the adsorption machine. At this time, the semiconductor wafer is attracted by placing the surface side on the machine side.

(3.3. Step 3)
After step 1 and step 2, the back surface of the semiconductor wafer on the adsorption machine is ground and the semiconductor wafer is singulated into a plurality of semiconductor wafers.

Here, since the semiconductor wafer is formed with trenches having a depth shallower than the thickness of the semiconductor wafer, the back surface grinding is performed until the semiconductor wafer is thinned to at least the bottom of the trench. By this back surface grinding, the trench becomes a cut through the wafer, and the semiconductor wafer is divided by the cut, and the individual wafers are formed into individual wafers.

The shape of the sliced semiconductor wafer may be a square, or an elongated shape such as a rectangle. The thickness of the individualized semiconductor wafer is not particularly limited, but is preferably about 5 to 100 μm, and more preferably 10 to 45 μm. Further, by the size of a sheet of semiconductor wafer is not particularly limited, wafer size preferably less than 50mm ^2, more preferably less than 30mm ^2, further more preferably less than 10mm ^2.

After the back grinding is completed, dry polishing is performed.

Grinding on the backside is because the grinding marks remain on the backside of the wafer, which is the main reason for damaging the bending strength of the wafer. As a result of the thinness and miniaturization of the wafer, it is considered that the wafer is easily damaged and the flexural strength is low. In order to remove the grinding marks (damaged portions) as described above, it is preferable to further remove the damaged portions and improve the bending strength of the wafer by dry polishing without using water after the back surface grinding.

However, unlike backside grinding, because water is not used during dry polishing, the heat generated during grinding cannot be removed by water, causing the wafer to contain heat. The heat of the wafer is transferred to the adhesive tape to which the wafer is attached. As a result, during the dry polishing, the temperature of the adhesive tape becomes 60 ° C. or higher, and the holding force of the adhesive tape on the wafer becomes insufficient, and the wafer may peel and scatter. However, by using the adhesive tape of the present invention, deformation of the adhesive tape can be suppressed, and wafer scattering can be reduced. Therefore, in the pre-cut method including the dry polishing step, in order to hold a semiconductor wafer, a wafer, etc., the adhesive tape of the present invention can be particularly suitably used.

That is, by using the adhesive tape of the present invention, even such a thin and / or small semiconductor wafer can be prevented during back grinding and dry polishing (step 3) and peeling of the adhesive tape (step 4). The semiconductor wafer is defective.

(3.4. Step 4)
Next, the adhesive tape is peeled from the singulated semiconductor wafer (ie, the plurality of semiconductor wafers). For example, this step is performed using the following method.

First, when the adhesive layer of the adhesive tape is formed of an energy-ray-curable adhesive, the energy layer is irradiated to harden the adhesive layer. Next, a pickup tape is affixed to the back surface side of the individualized semiconductor wafer, and the position and direction are aligned so that it can be picked up. At this time, the ring frame arranged on the outer peripheral side of the wafer is also bonded to the pickup tape, and the outer peripheral edge portion of the pickup tape is fixed to the ring frame. The wafer and the ring frame can be attached to the pickup tape at the same time, or they can be attached at different time points. Next, the adhesive tape is peeled from the plurality of semiconductor wafers fixed to the pickup tape.

Subsequently, a plurality of semiconductor wafers on the pickup tape are picked up and fixed on a substrate or the like to manufacture a semiconductor device.

The pick-up tape is not particularly limited, and may be, for example, an adhesive sheet including a base material and an adhesive layer provided on one surface of the base material.

Furthermore, it is also possible to use an adhesive tape instead of a pickup tape. The adhesive tape includes a laminate of a film-shaped adhesive and a release sheet, a laminate of a dicing tape and a film-shaped adhesive, an adhesive layer having a function of both a dicing tape and a die-bonding tape, and a release sheet. Cutting and die bonding tape. In addition, before attaching the pickup tape, a film-shaped adhesive may be bonded to the back surface side of the individual semiconductor wafer. When a film-shaped adhesive is used, the film-shaped adhesive may have the same shape as a wafer.

In the case of using an adhesive tape, the case where a film-shaped adhesive is adhered to the back side of a singulated semiconductor wafer before attaching the pickup tape, etc. Each semiconductor wafer is picked up together with an adhesive layer that is divided into the same shape. Then, the semiconductor wafer is fixed on the substrate or the like through the adhesive layer to manufacture a semiconductor device. Next, the agent layer can be divided using laser, expansion, or the like.

In the foregoing, the method for singulating a semiconductor wafer by a pre-cut method and performing dry polishing has been described mainly using an example of the adhesive tape of the present invention.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment at all, It can change and adopt various aspects within the scope of this invention.
[Example]

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples.

The measurement method and evaluation method in this example are as follows.

(Tensile storage modulus)
A 15 mm width × 2310 mm (length) measurement film made of the same material as the film or sheet constituting the substrate was prepared. Using a dynamic viscoelastic device (manufactured by ORIENTEC, trade name "Rheovibron DDV-II-EP1"), the tensile die at a frequency of 11 Hz and a temperature range of -20 to 150 ° C was measured for 10 samples of the measurement film. number. The average value of the tensile modulus of 10 samples at 60 ° C. was set to E ′ ₆₀ .

(Evaluation of wafer scattering)
The pressure-sensitive adhesive tapes with peeling sheets obtained in the examples and comparative examples were attached to a tape laminating machine (produced by LINTEC Corporation, trade name "RAD-3510") while peeling off the peeling sheets, and attached under the following conditions A 12-inch silicon wafer (thickness: 760 μm) with grooves formed on the wafer surface using a pre-cut method.
Roller height: 0mm
Roller temperature: 23 ° C (room temperature)
Machine temperature: 23 ° C (room temperature)

The obtained silicon wafer with an adhesive tape was singulated into pieces each having a thickness of 30 μm and a wafer size of 1 mm using back surface grinding (pre-cut method).

After the back surface grinding was completed, the ground surface was dry polished using DPG8760 manufactured by DISCO. As the polishing wheel, "Gettering DP" manufactured by DISCO Corporation was used. The dry polishing removes the damaged portion (grinding trace) of the wafer.

After the dry polishing was completed, the state of the wafer held at the end of the adhesive tape was visually observed, and it was confirmed whether the wafer was scattered. The wafer was judged to be "good" when there was no scattering, and the wafer was judged to be "bad" when it was scattered. In addition, since the wafer existing in the outermost region of the silicon wafer has a different shape (usually a triangular shape) from a wafer having a desired shape (usually a square shape), the above evaluation does not consider the Flying away. That is, the above-mentioned evaluation is only performed to evaluate the presence or absence of scattering of the tetragonal wafer.

In addition, all the mass parts of the following examples and comparative examples are solid content values.

(Multilayer substrate)
A polyethylene terephthalate film (tensile storage modulus: 2500 MPa) having a thickness of 25.0 μm and 75.0 μm was used as a substrate. A multi-layered substrate having a buffer layer (LDPE, low-density polyethylene) having a thickness of 27.5 μm provided on both sides of the substrates was prepared. Therefore, the structure of the multilayer substrate is as follows.
Multilayer substrate 1: LDPE (27.5μm) / PET (25.0μm) / LDPE (27.5μm)
Multilayer substrate 2: LDPE (27.5μm) / PET (75.0μm) / LDPE (27.5μm)

(Preparation of Adhesive Composition A)
Acrylic polymer (a) obtained by copolymerizing 65 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 15 parts by mass of 2-hydroxyethyl acrylate (HEA), followed by 80 mol% of the total hydroxyl groups of the acrylic polymer (a) were added to react a 2-methacryloyloxyethyl isocyanate (MOI) to obtain an energy ray-curable acrylic Resin (Mw: 500,000).

With respect to 100 parts by mass of the obtained energy ray-curable acrylic polymer, 6 parts by mass of urethane acrylate oligomer (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., UT-4220) as an energy ray-curable compound is mixed, Toluene diisocyanate cross-linking agent (manufactured by TOSOH, product name "CORONATE L") 0.375 parts by mass (solid content), and photopolymerization initiator (manufactured by Ciba Specia1ty Chemica1s Co., Ltd., product name "IRGACURE 184") 1.00 mass Parts (solid ratio) to obtain energy ray-curable adhesive composition A.

(Preparation of Adhesive Composition B)
An acrylic polymer (a) obtained by copolymerizing 52 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (HEA) was prepared by A 90 mol% hydroxyl group was added to the total hydroxyl groups of the acrylic polymer (a), and 2-methacryloxyethyl isocyanate (MOI) was reacted to obtain an energy ray-curable acrylic resin (Mw :600000).

With respect to 100 parts by mass of the obtained energy ray-curable acrylic polymer, 0.50 parts by mass (solid content) of toluene diisocyanate-based crosslinking agent (manufactured by TOSOH Corporation, product name "CORONATE L"), and photopolymerization initiation 3.70 parts by mass (solid ratio) of an agent (manufactured by Ciba Specia1ty Chemica1s Co., Ltd., product name "IRGACURE 184") to obtain an energy ray-curable adhesive composition B.

(Example 1)
On the release-treated surface of a release sheet (manufactured by LINTEC Co., Ltd., trade name: SP-PET381031), the coating solution of the energy ray-curable adhesive composition A obtained above was applied and dried at 100 ° C. For 20 minutes, an adhesive layer having a thickness of 20 μm was formed on the release sheet.

The formed adhesive layer is adhered to one side of the multi-layered substrate 1 to produce an adhesive tape. With respect to the obtained adhesive tape, the tensile storage modulus E ′ ₆₀ of the substrate at 60 ° C. was measured, and the scattering of the wafer was evaluated. The results are shown in Table 1.

(Example 2)
An adhesive tape was produced in the same manner as in Example 1 except that the multi-layer substrate 2 was used as the substrate. For the obtained adhesive tape was measured at 60 deg.] C of the substrate a tensile storage modulus E _'60, and evaluated for scattering the wafer. The results are shown in Table 1.

(Comparative example 1)
An adhesive tape was produced in the same manner as in Example 1 except that a polyvinyl chloride having a thickness of 80 μm was used as the base material and the adhesive composition B was used as the adhesive layer. For the obtained adhesive tape was measured at 60 deg.] C of the substrate a tensile storage modulus E _'60, and evaluated for scattering the wafer. The results are shown in Table 1.

(Comparative example 2)
An adhesive tape was produced in the same manner as in Example 1 except that a polyolefin having a thickness of 80 μm was used as the base material and the adhesive composition B was used as the adhesive layer. For the obtained adhesive tape was measured at 60 deg.] C of the substrate a tensile storage modulus E _'60, and evaluated for scattering the wafer. The results are shown in Table 1.

[Table 1]
In the table, "aE + b" means a × 10 ^b

From Table 1, it can be confirmed that when the tensile storage modulus E ′ ₆₀ of the substrate at 60 ° C. falls within the above range, scattering of the wafer can be suppressed.

no.

no.

Claims (2)

An adhesive tape is used for grinding the back surface of a semiconductor wafer having grooves formed on the surface of the semiconductor wafer, and singulating the semiconductor wafer into semiconductor wafers by the grinding, and then performing dry polishing. In the step, the adhesive tape used on the surface of the semiconductor wafer is used. Including a substrate and an adhesive layer provided on one side thereof; and The tensile storage modulus of the aforementioned substrate at 60 ° C is 250 MPa or more. A method for manufacturing a semiconductor device includes the following steps: A step of forming a trench from a surface side of a semiconductor wafer; A step of attaching an adhesive tape including a substrate and an adhesive layer provided on one side thereof and a tensile storage modulus of the substrate at 60 ° C. of 250 MPa or more, to the surface of the semiconductor wafer; A step of grinding the semiconductor wafer with the aforementioned adhesive tape on its surface and forming the aforementioned groove from the back side, and removing the bottom of the aforementioned groove to form a single wafer into a plurality of wafers; After the aforementioned semiconductor wafer is singulated into a semiconductor wafer, a step of dry polishing is performed; and The step of peeling the wafer from the aforementioned adhesive tape.