JP2013199562A - Sheet substrate for workpiece processing and sheet for workpiece processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of dicing debris occurring at the time of dicing a workpiece without applying physical energy such as electron beams and γ rays.SOLUTION: A substrate includes a block copolymer shown by the following formula: (high Tg block)-{(low Tg block)-(high Tg block)}n, wherein: n is an integer of 1 to 3; the high Tg block is a polymer block comprising a monomer unit whose homopolymer has 0°C or higher glass transition temperature; the low Tg block is a polymer block comprising a monomer unit whose homopolymer has lower than 0°C glass transition temperature; the difference between the glass transition temperature of the high Tg block and the glass transition temperature of the low Tg block is 30°C or more; and 25 mass% or more of the high Tg monomer is contained in 100 mass% of whole monomers used for polymerization of the block copolymer.

Description

  The present invention relates to a substrate used for a workpiece processing sheet on which a workpiece is stuck and held when a workpiece such as a semiconductor wafer (hereinafter sometimes referred to as “work”) is processed such as dicing. The present invention relates to a material, and the present invention relates to a workpiece processing sheet provided with such a substrate.

  Various adhesive sheets and film adhesives are used in a series of steps of dicing a workpiece such as a semiconductor wafer and die bonding the obtained chip.

  For example, the pressure-sensitive adhesive sheet used in the dicing process consists of a base material and a pressure-sensitive adhesive layer, and when the work such as a semiconductor wafer is diced, the work is fixed and the chip is held after dicing. Used to do. Further, a chip diced on the pressure-sensitive adhesive sheet may be directly picked up from the pressure-sensitive adhesive sheet, or may be picked up after the chip is transferred to the pressure-sensitive adhesive sheet for pickup.

  A dicing / die-bonding sheet has also been proposed that has both a wafer fixing function during dicing and a die bonding function during die bonding. The dicing / die-bonding sheet is composed of an adhesive resin layer having both a wafer holding function and a die bonding function, and a base material. The adhesive resin layer holds a semiconductor wafer or chip in the dicing process, and functions as an adhesive for fixing the chip during die bonding. At the time of dicing, the adhesive resin layer is cut together with the wafer, and an adhesive resin layer having the same shape as the cut chip is formed. When the chip is picked up after the dicing is completed, the adhesive resin layer is peeled off together with the chip. The chip with the adhesive resin layer is placed on the substrate, heated, etc., and the chip and the substrate are bonded via the adhesive resin layer. Such a dicing / die-bonding sheet is formed by forming an adhesive resin layer having both a wafer fixing function and a die bonding function on a substrate.

  In addition, in order to form a protective film on the surface of the chip, a semiconductor wafer is attached to the curable resin layer, the resin layer is cured, and then the semiconductor wafer and the resin layer are diced, and the cured resin layer (protective film) A process for manufacturing a chip having) has also been proposed. Such a sheet for forming a protective film has an adhesive resin layer serving as a protective film on a peelable substrate.

  Hereinafter, the above-described dicing sheet, pickup adhesive sheet, dicing / die-bonding sheet, and protective film forming sheet are collectively referred to as “work processing sheet”. In addition, the pressure-sensitive adhesive layer having the pressure-sensitive adhesive property as described above, the adhesive resin layer having both the wafer holding function and the die bonding function, and the adhesive resin layer serving as a protective film are simply referred to as “adhesive resin layer”. May be described.

  In such a workpiece processing sheet, a polyolefin film or a polyvinyl chloride film is usually used as a base material.

  In general full-cut dicing as a specific method of the dicing process, the workpiece is cut by a rotating round blade. At this time, not only the workpiece but also the adhesive resin layer may be cut, and a part of the base material may be further cut so that the workpiece to which the workpiece processing sheet is attached is surely cut.

  At this time, the dicing waste which consists of the material which comprises an adhesive resin layer and a base material generate | occur | produces from the sheet | seat for workpiece | work processing, and the chip | tip obtained may be contaminated with the dicing waste. One form of such dicing waste is thread-like dicing waste. The thread-like dicing waste adheres to the chip and may be accompanied by the chip during pickup.

  When sealing the chip with the thread-like dicing waste as described above attached to the chip, the thread-like dicing waste attached to the chip is decomposed by the heat of sealing, and this thermal decomposition product destroys the package, It may cause malfunction in the obtained device. Since this thread-like dicing waste is difficult to remove by washing, the yield of the dicing process is significantly reduced due to the occurrence of thread-like dicing waste. Therefore, when dicing is performed using a workpiece processing sheet, it is required to prevent generation of thread-like dicing waste.

  In addition, when dicing a package in which a plurality of chips are sealed with a cured resin as a workpiece, a dicing blade having a thicker blade width is used than in the case of dicing a semiconductor wafer, and the cutting depth of dicing is also increased. Become deeper. For this reason, since the amount of base material cut and removed during dicing is larger than in the case of a semiconductor wafer, the amount of thread-like dicing waste generated also increases.

  On the other hand, when a film that is difficult to soften, such as a polyester resin, is used as the substrate, the generation of dicing waste is suppressed. However, such films are practically impossible to expand due to high tensile stress. For this reason, after the work is made into chips, the chip interval cannot be separated, and chip pickup becomes difficult.

  For the purpose of suppressing the generation of dicing waste, Patent Document 1 discloses an invention using a polyolefin film irradiated with 1 to 80 Mrad of electron beam or γ (gamma) ray as a base film of a dicing sheet. ing. In the said invention, since resin which comprises a base film bridge | crosslinks by irradiation of an electron beam or a gamma ray, and it becomes difficult to melt | dissolve a base material, it is thought that generation | occurrence | production of a dicing waste is suppressed.

  In Patent Document 1, polyethylene, polypropylene, polymethylpentene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene-methyl are used as polyolefin films irradiated with electron beams or γ rays. Examples include (meth) acrylic acid ester copolymers, ethylene-ethyl (meth) acrylic acid copolymers, ethylene-ionomer copolymers, ethylene-vinyl alcohol copolymers, and polybutenes.

Japanese Patent Laid-Open No. 5-21234

  However, since the electron beam or γ-ray irradiation is performed after the above resin is once formed into a film shape, the number of manufacturing steps is increased, and the manufacturing cost tends to be higher than that of a general base film. It is in.

  The present invention has been made in view of the actual situation as described above, and does not give physical energy such as an electron beam or γ-ray, and generates dicing waste, particularly yarn-like dicing waste, generated when dicing a workpiece. It aims at providing the means which suppresses.

The present invention for solving the above problems includes the following gist.
(1) A base material used for a workpiece processing sheet and including a block copolymer represented by the following formula:
(High Tg block)-{(Low Tg block)-(High Tg block)} n
here,
n is an integer of 1 to 3,
The high Tg block is a polymer block composed of monomer units having a homopolymer glass transition temperature of 0 ° C. or higher.
The low Tg block is a polymer block composed of monomer units having a glass transition temperature of the homopolymer of less than 0 ° C.,
The difference between the glass transition temperature of the high Tg block and the glass transition temperature of the low Tg block is 30 ° C. or more,
In 100% by mass of all monomers used for the polymerization of the block copolymer, 25% by mass or more of high Tg monomer is contained.

(2) The work processing sheet according to (1), wherein the Young's modulus of the film including the block copolymer constituting the substrate is 300 MPa or less.

(3) A workpiece processing sheet having an adhesive resin layer on at least one surface of the substrate according to (1) or (2).

(4) The work processing sheet according to (3), wherein the adhesive resin layer has pressure-sensitive adhesiveness.

(5) The work processing sheet according to (3), wherein the adhesive resin layer is for die bonding.

(6) The workpiece processing sheet according to (3), wherein the adhesive resin layer is for forming a protective film.

  According to the base material and the workpiece processing sheet according to the present invention, it is possible to effectively reduce dicing waste generated during dicing of the workpiece without applying physical energy such as electron beams and γ rays. Since the base material and the workpiece processing sheet do not require electron beam or γ-ray processing, production is easy.

It is sectional drawing of the sheet | seat for workpiece | work processing which concerns on one Embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a base material according to the present invention and a workpiece processing sheet provided with the base material will be described with reference to the accompanying drawings.

  The base material which concerns on this invention is a resin-made sheet | seat used as the base material 2 of the sheet | seat 1 for workpiece | work processing represented by said dicing sheet and the sheet | seat for dicing die-bonding together, and contains a block copolymer. This base material is preferably used as a base material for a workpiece processing sheet used in a process including a step of cutting a part of the base material.

<Base material>
The block copolymer constituting the substrate has a structure represented by the following formula.
(High Tg block)-{(Low Tg block)-(High Tg block)} n
here,
n is an integer of 1 to 3, preferably an integer of 1 to 2, particularly preferably 1. In this case, the block copolymer is a triblock copolymer.

  The high Tg block is a polymer chain composed of monomer units having a glass transition temperature (Tg) of the homopolymer of 0 ° C. or higher, preferably 50 to 300 ° C., more preferably 70 to 200 ° C.

  Specific examples of the monomer having a homopolymer Tg of 0 ° C. or higher include the following high Tg monomers. In addition, in the following, the number in a parenthesis shows Tg (degreeC) of a homopolymer.

  Acrylic acid (103 ° C), methacrylic acid (228 ° C), methyl acrylate (10 ° C), methyl methacrylate (105 ° C), vinyl acetate (32 ° C), acrylamide (109 ° C), styrene (100 ° C) In general, it is called a high Tg monomer. Among these high Tg monomers, methyl methacrylate, methyl acrylate, vinyl acetate, and acrylamide are particularly preferably used. When such a high Tg monomer is used, it is difficult for the high Tg monomers to have an electrostatic interaction in the block copolymer, and the high Tg monomer in the monomer used for the polymerization of the block copolymer is Even if the ratio is increased, the flexibility of the substrate is easily maintained. Further, as the high Tg monomer, methyl methacrylate having low reactivity and high homopolymer Tg is particularly preferable.

  The high Tg block may be a block composed of one polymer chain of the high Tg monomer, or may be a copolymer block obtained by copolymerizing two or more high Tg monomers. The polymerization degree of one high Tg block is preferably 50 to 1000, more preferably 100 to 500. Further, the glass transition temperature of the high Tg block calculated from the Fox formula is preferably 50 to 300 ° C, more preferably 70 to 200 ° C. The formula of Fox is shown by the following formula. Therefore, the glass transition temperature of the high Tg block can be controlled by the type and ratio of the high Tg monomer. Specifically, the glass transition temperature of the high Tg block can be increased by increasing the ratio of the monomer component having a high Tg of the homopolymer.

1 / Tg = w1 / Tg1 + w2 / Tg2 (Fox's formula)
Tg1, Tg2: Tg (K) of homopolymer of monomer components 1 and 2
w1, w2: weight fraction of monomer components 1 and 2

  Further, the plurality of high Tg blocks present in the block copolymer may have the same composition or may be different.

  The low Tg block is a polymer block composed of monomer units having a glass transition temperature (Tg) of a homopolymer of less than 0 ° C, preferably -120 to 0 ° C, more preferably -80 to -10 ° C.

Specific examples of the monomer having a Tg of less than 0 ° C. include the following low Tg monomers. In addition, in the following, the number in a parenthesis shows Tg (degreeC) of a homopolymer.
Ethyl acrylate (-24 ° C), butyl acrylate (-54 ° C), butyl methacrylate (-24 ° C), hexyl acrylate (-57 ° C), hexyl methacrylate (-5) ° C, 2-ethylhexyl acrylate (−70 ° C.), ethylene (−125 ° C.), isoprene (−73 ° C.), butadiene (−7 ° C.), and vinylidene chloride (−18 ° C.) are hereinafter collectively referred to as low Tg monomers. Among these low Tg monomers, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, which are easily block copolymerized with methyl methacrylate, which is preferable as a high Tg monomer, 2-ethylhexyl acrylate is preferably used, and ethyl acrylate, butyl acrylate, and butyl methacrylate, in which the homopolymer Tg is not excessively low, are particularly preferable.

  The low Tg block may be a block composed of a polymer chain of one kind of the low Tg monomer, or may be a copolymer block obtained by copolymerizing two or more kinds of low Tg monomers. The degree of polymerization of the low Tg block is preferably 200 to 2000, more preferably 300 to 1000. The glass transition temperature of the low Tg block calculated from the Fox equation is preferably −120 to 0 ° C., more preferably −80 to −10 ° C. The glass transition temperature of the low Tg block can be controlled by the type and ratio of the low Tg monomer. Specifically, the glass transition temperature of the low Tg block can be lowered by increasing the ratio of the monomer component having a low Tg of the homopolymer.

  When n is 2 or more, the plurality of low Tg blocks present in the block copolymer may have the same composition or may be different.

  The difference between the glass transition temperature of the high Tg block calculated from the Fox equation and the glass transition temperature of the low Tg block is 30 ° C. or higher, preferably 80 to 300 ° C., more preferably 100 to 250 ° C. It is. Here, when a plurality of high Tg blocks having different compositions are present, the value of the high Tg block having the lowest glass transition temperature is adopted, and when a plurality of low Tg blocks having different compositions are present, the highest glass is employed. The value of the high Tg block having a transition temperature is adopted, and these differences are defined as the above glass transition temperature differences.

  In 100% by mass of all monomers used for polymerization of the block copolymer, the proportion of the high Tg monomer is 25% by mass or more, preferably 30 to 60% by mass, more preferably 35 to 60% by mass. It is. When the proportion of the high Tg monomer is too small, the generation of dicing waste cannot be suppressed even if a block copolymer having both ends composed of high Tg blocks is used as the substrate. When the film containing the block copolymer in the substrate contains a plurality of types of block copolymers, the ratio of the high Tg monomer in 100% by mass of all monomers used for the polymerization of the block copolymer is: The average of those things.

  The weight average molecular weight of the block copolymer is preferably 30,000 or more, more preferably 40,000 to 200,000. When the molecular weight of the block copolymer is too high, the viscosity of a solution obtained by dissolving the block copolymer in an organic solvent increases, and film formation may be difficult. On the other hand, if the molecular weight of the block copolymer is too low, the film-forming property may be inferior and the film may not be formed.

  By using the block copolymer as the main component of the base material, sufficient expandability is imparted to the base material, and even if a part of the base material is cut during dicing, the yarn-shaped dicing Waste generation is reduced. Although not limited theoretically, the present inventors presume the mechanism of the above effect as follows.

  That is, due to the presence of the low Tg block, the substrate has flexibility and sufficient expandability can be obtained. However, the low Tg block itself is easy to melt, and if a part of the base material is cut by the dicing blade, it melts by the frictional heat at that time, and is stretched by the rotation of the blade, which may generate thread-like debris There is.

  However, since the high Tg block exists at both ends of the copolymer, the block copolymer itself has a structure that is difficult to melt while being softened. For this reason, although a base material is flexible, it shows the property of being hard to melt | dissolve and it is thought that generation | occurrence | production of a filamentous waste is suppressed.

  Although the manufacturing method of a block copolymer is not specifically limited, A block copolymer is easy to be obtained by using a living polymerization method. When the above-mentioned preferable monomers are selected as the high Tg monomer and the low Tg monomer, it is preferable to use a living radical polymerization method. After polymerizing or copolymerizing a low Tg monomer to produce a low Tg block, by polymerizing or copolymerizing a high Tg monomer in the presence of the low Tg block, both ends are high Tg blocks, and an intermediate block A low Tg block triblock copolymer. In the presence of the triblock copolymer, n in the above formula can be increased by further repeating polymerization or copolymerization of a low Tg monomer and subsequent polymerization or copolymerization of a high Tg monomer. In the final step, by polymerizing or copolymerizing the high Tg monomer, a multi-block copolymer having a high Tg block at both ends can be obtained.

  If the polymerization of the low Tg monomer and the polymerization of the high Tg monomer are performed alternately, unreacted low Tg monomer may also be polymerized when the high Tg monomer is polymerized, and the low Tg monomer unit may be included in the high Tg block. And vice versa. Accordingly, the high Tg block may contain a low Tg monomer unit in a proportion of less than 5% by mass, and the low Tg block contains a high Tg monomer unit in a proportion of less than 5% by mass. Also good.

  The base copolymer of the present invention contains the block copolymer. The substrate may be a single layer film containing a block copolymer, or may be a laminate of a film containing a block copolymer and another resin film. The thickness of the substrate is preferably in the range of 20 to 300 μm, more preferably 60 to 200 μm. If the thickness of the substrate is too thin, when the substrate is cut with a dicing blade, the thickness of the portion becomes extremely thin, and there is a possibility of tearing during expansion. If it is too thick, the force against tension increases, and the expandability may decrease.

  When the substrate is a single layer film, the film may be composed only of the above block copolymer, and other copolymers such as polyolefin and polyvinyl chloride, filler, colorant, antistatic agent, oxidation An inhibitor, an organic lubricant, etc. may be contained. Such other components can be blended in a proportion of, for example, 50% by mass or less in 100% by mass of the solid content constituting the substrate. In order to exert the effect derived from the block copolymer of the present invention, the proportion of the block copolymer in the solid content constituting the base material is preferably as large as possible, and the solid content constituting the base material is 100 mass. %, The block copolymer is preferably contained in a proportion of 50% by mass or more, more preferably 50 to 100% by mass, particularly preferably 90 to 100% by mass. The above block copolymer can relatively increase the proportion of high Tg monomer in the monomer used for polymerization of the block copolymer, and control the properties of the substrate to some extent by the high proportion of the high Tg monomer. can do. Therefore, it is not necessary to control the properties of the base material by adding a copolymer other than the block copolymer, and the production method and formulation can be simplified and the productivity is excellent.

  The method for producing a film containing such a block copolymer is not particularly limited, but the block copolymer, other additives, and an appropriate solvent or dispersion medium are mixed, and the resulting solution or dispersion is appropriately mixed. The film containing a block copolymer is obtained by coating and drying by a coating means. Alternatively, a melt extrusion method or a calendar method generally used for film formation may be used.

  The Young's modulus of the film containing the block copolymer is preferably 300 MPa or less, and preferably 200 to 100 MPa. When the Young's modulus of the film containing the block copolymer is in such a range, when the substrate is a single-layer film of the block copolymer film, it is easy to improve the expandability of the substrate. Become. In addition, when the substrate is a laminate of a film containing a block copolymer and another film, when the workpiece processing sheet is diced, the film containing the block copolymer is completely cut. Even if not, the film containing the remaining block copolymer is unlikely to hinder expansion.

  When the substrate is a laminate, the block copolymer and other resin may be used as a substrate by coextrusion. Alternatively, the film containing the block copolymer and another resin film are integrated by dry lamination or an adhesive, or the block copolymer is softened by heating to about 40 to 90 ° C. A base material can also be obtained by bonding to a resin film. Examples of other resin films include polyethylene films such as low density polyethylene (LDPE) films, linear low density polyethylene (LLDPE) films, and high density polyethylene (HDPE) films, polypropylene films, polybutene films, polybutadiene films, and polymethyl. Penten film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, polyimide film, ethylene vinyl acetate copolymer film, ionomer resin film, ethylene / (meth) acrylic acid copolymer Polymer film, ethylene (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, fluorine resin Films, and films are used consisting of the hydrogenated product or modified product or the like. These crosslinked films and copolymer films are also used. As another resin film, it is preferable to use one or more soft films having a tensile stress at 25% elongation of 100 MPa or less. The tensile stress at 25% elongation of the flexible film is more preferably 50 MPa or less. By making a base material into a laminated body using such a soft film, the expandability of the base material is further improved.

  Moreover, when a base material is a laminated body, the below-mentioned adhesive resin layer is formed on the film containing a block copolymer. The layer constituting the base material immediately below the adhesive resin layer is cut by a dicing blade during dicing, and the layer constituting the base material immediately below the adhesive resin layer is a film containing the block copolymer. Thereby, even if it is a case where a base material is cut at the time of dicing, the generated dicing waste can be reduced effectively. Here, “directly” includes a state in which a layer made of a primer or a release agent, which will be described later, is interposed as long as the effect of reducing dicing waste of the present invention is not impaired.

  The film containing the block copolymer contains 10% by mass of other components such as other copolymers, fillers, colorants, antistatic agents, antioxidants, and organic lubricants as in the case of the single layer substrate. It may be included in the following ratio.

  In the case where the substrate is a laminate, the thickness of the entire substrate is preferably in the range as described above, but the thickness of the film containing the block copolymer is preferably 10 to 100 μm, more preferably 20 to 20 μm. 50 μm.

  In order to improve the adhesiveness with the adhesive resin layer, the surface of the substrate that contacts the adhesive resin layer may be subjected to corona treatment or other layers such as a primer. Furthermore, when peeling the adhesive resin layer from the substrate and transferring the adhesive resin layer to the chip, etc., it is peeled off from the substrate surface to facilitate peeling between the adhesive resin layer and the substrate. Processing may be performed. In this case, the surface tension of the substrate is preferably 40 mN / m or less, more preferably 37 mN / m or less, and particularly preferably 25 to 35 mN / m. As the release agent used for the release treatment, alkyd, silicone, fluorine, unsaturated polyester, polyolefin, wax, and the like are used. In particular, alkyd, silicone, and fluorine release agents are heat resistant. This is preferable.

  In order to release the surface of the substrate using the above release agent, the release agent can be applied as it is without solvent, or after solvent dilution or emulsification, using a gravure coater, Mayer bar coater, air knife coater, roll coater, etc. However, it is preferable to use an ultraviolet curable release agent from the viewpoint of preventing deformation of the film containing the block copolymer due to heat.

<Adhesive resin layer>
The workpiece processing sheet 1 of the present invention has an adhesive resin layer 3 on at least one side of the base material 2 described above. When the base material is a laminate, an adhesive resin layer is formed on the film containing the block copolymer. The adhesive resin layer in the workpiece processing sheet is appropriately selected from resins having various functions depending on the use of the sheet.

(Pressure-sensitive adhesive resin layer)
When the workpiece processing sheet is used as a dicing sheet, the adhesive resin layer is preferably composed of a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) having removability. The above-mentioned base material is relatively soft, has excellent expandability, and the base material contains a specific block copolymer. Therefore, even when the dicing blade cuts the base material, the yarn-like dicing Waste generation is difficult to occur.

  The dicing sheet is used for holding a workpiece and a chip generated by dicing when a workpiece such as a semiconductor wafer is diced into chips. Therefore, it is required to have an appropriate re-peelability that can peel the chip after dicing. Such a pressure-sensitive adhesive layer can be formed by various conventionally known pressure-sensitive adhesives (pressure-sensitive adhesives). The pressure-sensitive adhesive is not limited at all. For example, a rubber-based, acrylic-based, silicone-based, polyvinyl ether, or other pressure-sensitive adhesive is used. Among these, an acrylic pressure-sensitive adhesive that can easily control the adhesive force is particularly preferable.

  The acrylic pressure-sensitive adhesive mainly comprises a (meth) acrylic acid ester polymer. (Meth) acrylic acid ester polymers include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylate-2-ethylhexyl, decyl acrylate, dodecyl acrylate, lauryl acrylate, myristyl acrylate, (Meth) acrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate, aromatic (meth) acrylic esters such as benzyl acrylate, cyclohexyl acrylate, and isobornyl acrylate. Group (meth) acrylic acid ester (hereinafter referred to as (meth) acrylic acid alkyl ester, aromatic (meth) acrylic acid ester, alicyclic (meth) acrylic acid ester, and only hydrocarbon added to the ester structure ( (Meth) acrylic And 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 3-hydroxybutyl acrylate, and acrylate-4 as required. -Hydroxyl-containing (meth) such as hydroxybutyl, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 3-hydroxybutyl methacrylate, and 4-hydroxybutyl methacrylate Acrylic acid alkyl esters; carboxyl group-containing compounds such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid; vinyl esters such as vinyl acetate and vinyl propionate; cyano group-containing compounds such as acrylonitrile and methacrylonitrile; acrylamide, etc. Amide group-containing compounds; styrene, and the like polymerizable homopolymer of one or more monomers selected from the monomers or copolymers of such aromatic compounds such as vinyl pyridine. Moreover, (meth) acryl is used in the meaning containing both acryl and methacryl.

  The content ratio of units derived from the (meth) acrylic acid ester in which only the hydrocarbon is added to the ester structure in the (meth) acrylic acid ester polymer is preferably 10 to 98% by mass, more preferably 20 to 95% by mass, 50-93 mass% is still more preferable. The weight average molecular weight of the (meth) acrylic acid ester polymer is preferably 100,000 to 2,500,000, more preferably 200,000 to 1,500,000, and particularly preferably 300,000 to 1,000,000. In the present specification, the weight average molecular weight is a value in terms of standard polystyrene measured by gel permeation chromatography.

  These pressure-sensitive adhesives can be used alone or in combination of two or more. Of these pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used. In particular, an acrylic polymer obtained by crosslinking the (meth) acrylic acid ester polymer with one or more of a crosslinking agent such as a polyisocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a chelating crosslinking agent. An adhesive is preferred.

  As the epoxy-based crosslinking agent, (1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycyl-m-xylylenediamine, N, N, N ′, N'-tetraglycidylaminophenyl methane, triglycidyl isocyanate, m-N, N-diglycidylaminophenyl glycidyl ether, N, N-diglycidyl toluidine, N, N-diglycidyl aniline, pentaerythritol polyglycidyl ether, 1 , 6-hexanediol diglycidyl ether and the like.

  Examples of polyisocyanate crosslinking agents include tolylene diisocyanate (TDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), hydrogenated tolylene diisocyanate, diphenylmethane diisocyanate and hydrogenated products thereof, poly Examples include methylene polyphenyl polyisocyanate, naphthylene-1,5-diisocyanate, polyisocyanate prepolymer, and polymethylolpropane-modified TDI.

  A crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type. As for the usage-amount of a crosslinking agent, 0.01-20 mass parts is preferable with respect to 100 mass parts of (meth) acrylic acid ester polymers.

  Furthermore, when using the workpiece | work processing sheet | seat as a dicing sheet, the adhesive layer may be an adhesive which can control adhesive force by energy ray hardening, heating foaming, water swelling, etc. The energy ray-curable pressure-sensitive adhesive layer can be formed of various energy ray-curable pressure-sensitive adhesives that are cured by irradiation with energy rays such as gamma rays, electron beams, ultraviolet rays, and visible light that are conventionally known. It is preferable to use an agent.

  Examples of the energy ray curable pressure sensitive adhesive include a pressure sensitive adhesive obtained by mixing a polyfunctional energy ray curable resin with an acrylic pressure sensitive adhesive. Examples of the polyfunctional energy ray curable resin include low molecular weight compounds having a plurality of energy ray polymerizable functional groups, urethane acrylate oligomers, and the like. Moreover, the adhesive containing the polymer which has an energy-beam polymerizable functional group in a side chain can also be used. Such an energy ray polymerizable functional group is preferably a (meth) acryloyl group.

  Such a dicing sheet has been widely used for semiconductor processing, and has an adhesive strength that fixes the wafer during dicing and prevents chips generated by dicing from scattering. After the dicing process is completed, the chip is picked up. At this time, a chip is picked up from the dicing sheet using a push-up pin, a suction collet, or the like. Further, when the pressure-sensitive adhesive layer has energy ray curability, the chip can be more easily picked up by irradiating the pressure-sensitive adhesive layer with energy rays to reduce the adhesive force. Further, when picking up the chips, it is preferable to expand the dicing sheet in a state where the chips are fixed to the dicing sheet in order to separate the intervals between the chips. By expanding, the distance between the chips is increased, the chips can be easily recognized, the damage due to the contact between the chips is reduced, and the yield is improved.

(Film adhesive)

  Furthermore, the work processing sheet of the present invention may be a dicing / die-bonding sheet having both a wafer fixing function during dicing and a die bonding function during die bonding. In this case, the adhesive resin layer has pressure-sensitive adhesiveness, or has a property of being softened by heating and attached to the adherend, whereby the semiconductor wafer or chip can be held in the dicing process. And it functions as an adhesive for fixing the chip during die bonding. At the time of dicing, the adhesive resin layer is cut together with the wafer, and an adhesive resin layer having the same shape as the cut chip is formed. When the chip is picked up after the dicing is completed, the adhesive resin layer is peeled off from the substrate together with the chip. A chip with an adhesive resin layer is placed on the substrate, heated, etc., and the chip and an adherend such as a substrate or another chip are bonded via the adhesive resin layer. In such a dicing / die-bonding sheet, an adhesive resin layer having both a wafer fixing function and a die bonding function is formed on a base material. Such an adhesive resin layer having both a wafer fixing function and a die bonding function includes, for example, a binder resin and an epoxy adhesive, and also includes an energy ray curable compound and a curing aid as necessary. In order to facilitate the transfer of the adhesive resin layer to the chip, it is preferable that the base material in the dicing / die-bonding sheet is subjected to a peeling treatment. In addition, when picking up the chip with the adhesive resin layer, it is preferable to perform the expansion in the same manner as described above.

(Protective film forming sheet)
Further, the workpiece processing sheet may be a protective film forming sheet for forming a protective film on the back surface of the chip. In this case, a semiconductor wafer is attached to the adhesive resin layer, the adhesive resin layer is cured, and then the semiconductor wafer and the resin layer are diced to obtain a chip having a cured resin layer (protective film). Such a sheet for forming a protective film has an adhesive resin layer serving as a protective film on a peelable substrate. The adhesive resin layer serving as a protective film contains, for example, a binder resin, an epoxy adhesive, and a curing aid, and may contain a filler or the like as necessary.

<Work processing sheet>
The thickness of the adhesive resin layer 3 in the workpiece processing sheet 1 of the present invention varies depending on the application, and is about 30 to 200 μm when used as a dicing sheet, and when used as a dicing / die-bonding sheet. 50 to 300 μm.
The adhesive resin layer 3 may be formed by directly coating on one side of the substrate 2, or after forming the adhesive resin layer on the release film, it may be transferred onto the substrate. .

  As described above, the representative composition and application of the adhesive resin layer have been outlined for the workpiece processing sheet of the present invention, but the adhesive resin layer in the workpiece processing sheet of the present invention is not limited to the above. Also, its use is not particularly limited.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The “Young's modulus of the film or substrate containing the block copolymer” was measured as follows, and “Dicing waste” and “Expandability” were evaluated as follows.

(Young's modulus of a film or substrate containing a block copolymer)
The Young's modulus of the film or base material containing the block copolymer is 23 ° C. and 50% humidity in accordance with JIS K7161: 1994 using a universal tensile tester (Tensilon RTA-T-2M manufactured by Orientec Co., Ltd.). The measurement was performed at a tensile speed of 200 mm / min. About Examples 1-4 and Comparative Example 1, it tests about the obtained base material, About Example 5, it tests about the film containing the block copolymer before making it laminate | stack with an ethylene methacrylic acid copolymer film. Went. In addition, the Young's modulus of the substrates used in Comparative Examples 2 and 3 was also measured for reference.

(Dicing waste)
After affixing the adhesive resin layer of the workpiece processing sheet prepared in the examples and comparative examples to a silicon wafer, it was set in a dicing apparatus (manufactured by DISCO, DFD-651) and diced under the following conditions.
・ Work (adherence): Silicon wafer ・ Work size: 6 inches, thickness 350μm
・ Dicing blade: NBC-ZH 2050 27HECC manufactured by DISCO
・ Blade rotation speed: 30,000rpm
・ Dicing speed: 80 mm / second ・ Incision depth: Incision to a depth of 20 μm from the substrate film surface ・ Dicing size: 10 mm × 10 mm

After dicing under the above conditions, ultraviolet rays were irradiated from the base film side (160 mJ / cm ² ), and the cut chips were peeled off. Among vertical and horizontal dicing lines, use a digital microscope (Keyence Corp., VHX-100, magnification: 100 times) to determine the number of filaments generated on one vertical line and one horizontal line near the center of each. And counted. The number of filamentous scraps of 0 to 10 was evaluated as good and 11 or more were evaluated as defective.

(Expandable)
After performing dicing and ultraviolet irradiation under the above-mentioned conditions, using an expanding apparatus (SE-100 manufactured by JCM), it was pulled down and expanded at a speed of 5 mm / s. The expandability was evaluated based on the maximum amount of withdrawal (length) that can be expanded. The longer the maximum withdrawal amount, the better the expandability.

Example 1
(Adhesive resin)
100 parts by mass of a polymer obtained by reacting 33.6 g of methacryloyloxyethyl isocyanate with 100 g of a copolymer comprising 40 parts by mass of 2-ethylhexyl acrylate, 40 parts by mass of vinyl acetate monomer and 20 parts by mass of 2-hydroxyethyl acrylate. And 3 parts by weight of an ultraviolet curable reaction initiator and 1 part by weight of a crosslinking agent (isocyanate) were blended to obtain an adhesive resin composition.

(Base material)
The proportion of methyl methacrylate in 100% by mass of all monomers used for polymerization of the block copolymer is 30% by mass, both ends are polymethyl methacrylate blocks (high Tg block), and the intermediate block is polyacrylic. A triblock copolymer (LA-2250, manufactured by Kuraray Co., Ltd.) having a weight average molecular weight of 50,000 which is an acid butyl block (low Tg block) was dissolved in methyl ethyl ketone to prepare a mixture. In the following experimental examples, similarly, the polymethyl methacrylate block is a high Tg block, and the polybutyl acrylate block is a low Tg block.

  The above mixed solution was applied to the first release film (SP-PET 381031, manufactured by Lintec Corporation, 38 μm thick polyethylene terephthalate film whose surface was peeled) so that the thickness after drying was 80 μm, It heated at 100 degreeC for 3 minute (s), and the base material which consists only of a film containing a block copolymer was formed.

(Work processing sheet)
The adhesive resin composition was applied on the surface of the second release film (SP-PET 381031 manufactured by Lintec Corporation) so as to have a thickness of 10 μm and heated at 100 ° C. for 1 minute. Next, the obtained adhesive resin layer and the substrate film were bonded together, the first and second release films were peeled off, and a workpiece processing sheet having an adhesive resin layer on the substrate was prepared.

  “Dicing waste” and “expandability” were evaluated using the obtained workpiece processing sheet. The results are shown in Table 1.

(Example 2)
As a triblock copolymer constituting the base material, the proportion of methyl methacrylate in 100% by mass of all monomers used for polymerization of the block copolymer is 30% by mass, and both ends are polymethyl methacrylate blocks. Yes, in the same manner as in Example 1 except that a triblock copolymer (LA-2550, manufactured by Kuraray Co., Ltd.) having a weight average molecular weight of 80000, in which the intermediate block is a polybutyl acrylate block, was used. A processing sheet was created. The results are shown in Table 1.

(Example 3)
As a triblock copolymer constituting the base material, the proportion of methyl methacrylate in 100% by mass of all monomers used for polymerization of the block copolymer is 30% by mass, and both ends are polymethyl methacrylate blocks. Yes, a triblock copolymer (LA-2250, manufactured by Kuraray Co., Ltd.) having a weight average molecular weight of 50,000, the intermediate block being a polybutyl acrylate block, and all monomers 100 used for polymerization of the block copolymer A triblock copolymer having a weight average molecular weight of 50000, wherein the ratio of methyl methacrylate in mass% is 50 mass%, both ends are polymethyl methacrylate blocks, and the intermediate block is polybutyl acrylate block ( Equal amount mixture with Kuraray Co., Ltd. (LA-4285) (polymerization of methyl methacrylate block copolymer) Except that the average percentage of the total monomers in 100% by mass there are using 40 wt%), the same procedure as in Example 1 to prepare a workpiece processing sheet. The results are shown in Table 1.

Example 4
As a triblock copolymer constituting the substrate, the proportion of methyl methacrylate in 100% by mass of all monomers used for polymerization of the block copolymer is 50% by mass, and both ends are polymethyl methacrylate blocks. Yes, in the same manner as in Example 1 except that a triblock copolymer having a weight average molecular weight of 50000 (LA-4285, manufactured by Kuraray Co., Ltd.), in which the intermediate block is a polybutyl acrylate block, was used. A processing sheet was created. The results are shown in Table 1.

(Example 5)
(Laminated substrate)
The proportion of methyl tacrylate in 100% by mass of all monomers used for polymerization of the meblock copolymer is 50% by mass, both ends are polymethyl methacrylate blocks, and the intermediate block is a polybutyl acrylate block. A triblock copolymer having a weight average molecular weight of 50,000 (Kuraray Co., Ltd., LA-4285) was dissolved in methyl ethyl ketone to prepare a mixture.

  The above mixed solution is applied onto the first release film (SP-PET 381031 manufactured by Lintec Corporation) so that the thickness after drying is 30 μm, and heated at 100 ° C. for 3 minutes to contain a block copolymer Formed.

  Subsequently, a 60 μm thick ethylene / methacrylic acid copolymer film (tensile stress at 25% elongation: 7.8 MPa) and the block copolymer film were heated to 60 ° C. and laminated to obtain a substrate.

(Work processing sheet)
A workpiece processing sheet was prepared in the same manner as in Example 1 except that an adhesive resin layer was formed on the side of the substrate containing the block copolymer. The results are shown in Table 1.

(Comparative Example 1)
As a triblock copolymer constituting the substrate, the proportion of methyl methacrylate in 100% by mass of all monomers used for polymerization of the block copolymer is 20% by mass, and both ends are polymethyl methacrylate blocks. Yes, in the same manner as in Example 1 except that a triblock copolymer having a weight average molecular weight of 50000 (LA-2140e, manufactured by Kuraray Co., Ltd.), in which the intermediate block is a polybutyl acrylate block, was used. A processing sheet was created. The results are shown in Table 1.

(Comparative Example 2)
A workpiece processing sheet was prepared in the same manner as in Example 1 except that an ethylene / methacrylic acid copolymer film having a thickness of 80 μm was used as the substrate. The results are shown in Table 1.

(Comparative Example 3)
A workpiece processing sheet was prepared in the same manner as in Example 1 except that a polyethylene terephthalate film having a thickness of 100 μm was used as the substrate. The results are shown in Table 1.

1: Work processing sheet 2: Base material 3: Adhesive resin layer

Claims (6)

A base material used for a workpiece processing sheet, comprising a block copolymer represented by the following formula:
(High Tg block)-{(Low Tg block)-(High Tg block)} n
here,
n is an integer of 1 to 3,
The high Tg block is a polymer block composed of monomer units having a homopolymer glass transition temperature of 0 ° C. or higher.
The low Tg block is a polymer block composed of monomer units having a glass transition temperature of the homopolymer of less than 0 ° C.,
The difference between the glass transition temperature of the high Tg block and the glass transition temperature of the low Tg block is 30 ° C. or more,
In 100% by mass of all monomers used for the polymerization of the block copolymer, the high Tg monomer is contained in an amount of 25% by mass or more.   The work processing sheet according to claim 1, wherein the Young's modulus of the film containing the block copolymer constituting the substrate is 300 MPa or less.   A work processing sheet having an adhesive resin layer on at least one surface of the substrate according to claim 1.   The work processing sheet according to claim 3, wherein the adhesive resin layer has pressure-sensitive adhesiveness.   The work processing sheet according to claim 3, wherein the adhesive resin layer is for die bonding.   The work processing sheet according to claim 3, wherein the adhesive resin layer is for forming a protective film.

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