Sheet material for workpiece processing

Abstract

This invention provides an adhesive sheet comprising a substrate and an adhesive layer laminated on one side of the substrate. The substrate is formed of a material containing a polyester resin having an alicyclic structure. Furthermore, the heat of fusion measured by differential scanning calorimetry at a heating rate of 20°C / min is 2 J / g or higher. This adhesive sheet can be manufactured with reduced manufacturing costs and can suppress the generation of cutting chips.

Description

[Technical Field]

[0001] The present invention relates to an adhesive sheet suitable for use as a workpiece processing sheet in the processing of workpieces such as semiconductor wafers. [Previous Technology]

[0002] Semiconductor wafers such as silicon and gallium arsenide, as well as various packages, are manufactured in a large-diameter state. After the wafers are diced and picked up, they are moved to the mounting step as the next step. At this time, the workpieces such as semiconductor wafers are attached to an adhesive sheet (hereinafter sometimes referred to as "workpiece processing sheet") having a substrate and an adhesive layer, and are processed by back grinding, dicing, cleaning, drying, expanding, picking up, and mounting.

[0003] As one of the aforementioned cutting methods, there is a method of cutting a workpiece by means of a rotating disc cutter (cutting edge). In this method, in order to reliably cut the workpiece, the workpiece processing sheet to which it is attached is usually also partially cut off along with the workpiece.

[0004] In this way, when the workpiece and the workpiece processing sheet are cut, cutting chips formed from the materials constituting the adhesive layer and the substrate will be generated from the workpiece processing sheet. In particular, such cutting chips usually occur near the path (kerf line) of the disc cutter in the wafer or workpiece processing sheet obtained by cutting.

[0005] When wafers are packaged with a large amount of cutting shavings adhering to them, the shavings decompose due to the heat of the packaging process. These thermal decomposition products damage the package and become a cause of failure in the resulting components. Since these cutting shavings are difficult to remove by washing, their occurrence significantly reduces the yield of the cutting process. Therefore, it is necessary to prevent the generation of cutting shavings when cutting with a rotating disc cutter.

[0006] Patent Document 1 discloses an invention for using a polyolefin film irradiated with electron beams or gamma rays at 1-80 Mrads as a substrate film for cutting sheets, with the aim of suppressing the generation of such cutting chips. This invention presumably suppresses the generation of cutting chips by forming crosslinks through covalent bonds in the resin constituting the substrate film through irradiation with electron beams or gamma rays. [Prior Art Documents] [Patent Documents]

[0007] Patent Document 1: Japanese Patent Application Publication No. 5-211234 [Summary of the Invention]

[0008] [The problem the invention aims to solve]

[0009] However, in the invention of Patent Document 1, since the irradiation is carried out after the resin has been formed into a film, as described above, an additional manufacturing step is added, and the manufacturing cost tends to be higher than that of a general substrate film.

[0010] This invention was made in view of this situation, and its object is to provide an adhesive sheet that can suppress manufacturing costs while further suppressing the generation of cutting chips. [Means of the Problem]

[0011] In order to achieve the above objective, firstly, the present invention provides an adhesive sheet having a substrate and an adhesive layer laminated on one side of the substrate, characterized in that: the substrate is formed of a material containing polyester resin, the polyester resin having an alicyclic structure, and the heat of fusion measured by differential scanning calorimetry at a heating rate of 20°C / min is 2 J / g or more (Invention 1).

[0012] The adhesive sheet related to the above invention (Invention 1) is formed by a substrate made of a material containing polyester resin, and the polyester resin has an alicyclic structure. Furthermore, by exhibiting the above-mentioned melting heat, the generation of cutting chips can be well suppressed even when used for cutting with a rotating disc cutter.

[0013] In the above invention (Invention 1), the polyester resin, as the monomer unit constituting the polyester resin, preferably contains a dicarboxylic acid having the above-mentioned alicyclic structure (Invention 2).

[0014] In the above inventions (Inventions 1 and 2), the polyester resin, as a monomer unit constituting the polyester resin, preferably contains a diol having the above-mentioned alicyclic structure (Invention 3).

[0015] In the above inventions (Inventions 1 to 3), the above-mentioned alicyclic structure is one in which the number of carbon atoms constituting the ring is 6 or more and 14 or less (Invention 4).

[0016] In the above inventions (Inventions 1 to 4), the polyester resin, as the monomer unit constituting the polyester resin, preferably contains a dimer acid formed by dimerizing an unsaturated fatty acid, and the unsaturated fatty acid has 10 or more carbon atoms and 30 or less (Invention 5).

[0017] In the above invention (Invention 5), the ratio of the dimer acid constituting the monomer unit of the polyester resin to all dicarboxylic acids constituting the monomer unit of the polyester resin is preferably 2 mol% or more and 25 mol% or less (Invention 6).

[0018] In the above inventions (Inventions 1 to 6), the tensile elastic modulus of the substrate at 23°C is 100 MPa or more and 800 MPa or less (Invention 7).

[0019] In the above inventions (Inventions 1 to 7), the fracture ductility of the above-mentioned substrate at 23°C is preferably 200% or more and 800% or less (Invention 8).

[0020] In the above inventions (Inventions 1 to 8), the thickness of the substrate is preferably 20 μm or more and 600 μm or less (Invention 9).

[0021] In the above inventions (Inventions 1 to 9), the adhesive layer is preferably composed of an acrylic adhesive (Invention 10).

[0022] In the above inventions (Inventions 1 to 10), it is preferable to use it as a sheet material for workpiece processing (Invention 11).

[0023] In the above-described invention (Invention 11), the sheet material for processing the workpiece is preferably used as a cutting sheet material (Invention 12). [Effects of the Invention]

[0024] The adhesive sheet related to the present invention can be manufactured locally with reduced manufacturing costs, and the generation of cutting chips can be suppressed.

Implementation Method

[0025] Hereinafter, embodiments of the present invention will be described. The adhesive sheet related to this embodiment has a substrate and an adhesive layer laminated on one side of the substrate. Although this adhesive sheet can be used for various applications like a general adhesive sheet, it is particularly suitable as a workpiece processing sheet for processing workpieces such as semiconductor wafers, and especially suitable as a cutting sheet for cutting workpieces.

[0026] 1. Composition of the adhesive sheet (1) Substrate The substrate in this embodiment is composed of a material containing polyester resin. The polyester resin has an alicyclic structure, and the heat of fusion measured by differential scanning calorimetry at a heating rate of 20°C / min is 2 J / g or more. Since the substrate is composed of a material containing a polyester resin having an alicyclic structure and exhibiting the above-mentioned heat of fusion, when the adhesive sheet related to this embodiment is used to cut a workpiece using a rotating disc cutter, the generation of cutting chips can be well suppressed.

[0027] The reasons for obtaining such chip suppression effect are speculated as follows. However, it is not excluded that the above effect can also be obtained by multiplying the following reasons with other reasons, and it is also not excluded that the above effect can be obtained based on reasons other than those listed below.

[0028] First, it is presumed that when a cutting force is applied to a substrate made using this polyester resin, the polyester resin becomes easily cut at the ester bond positions. Furthermore, the polyester resin in this embodiment, by having the alicyclic structure described above and exhibiting the aforementioned heat of fusion, has a portion of its polymer chain forming a moderately regularly folded structure (lamellar structure). Therefore, it is presumed that when a cutting force is applied, the polyester resin becomes easily cut at the lamellar structure positions. In this way, the polyester resin in this embodiment, compared to resins used in conventional substrates, becomes more easily cut at specific locations when a cutting force is applied.

[0029] Here, as a mechanism for generating cutting chips from a substrate of a general cutting sheet, it is speculated that the substrate softens due to the frictional heat generated during cutting, and furthermore, the cutting portion of the substrate is stretched and planed off due to the tensile force applied to the cut portion of the substrate by the rotating disc cutter. In particular, most of the cutting chips generated in this way become filamentous.

[0030] On the other hand, it is speculated that the substrate in this embodiment is effectively cut near the ester bonds and lamellar structure before being stretched as described above, and the generation of cutting chips is suppressed.

[0031] This chip suppression effect can still be achieved even if the substrate in this embodiment is not irradiated with radiation such as electron beams or gamma rays. Therefore, the adhesive sheet having this substrate can reduce manufacturing costs compared to conventional cutting sheets manufactured by methods including radiation irradiation steps.

[0032] Furthermore, the aforementioned polyester resin, as the substrate material, also exhibits good flexibility. Therefore, the adhesive sheet related to this embodiment becomes easier to stretch during the stretching step (elongation), and easier to lift from the back of the wafer during the wafer picking step, thereby making the wafer easier to pick up (pickup quality). Moreover, since the aforementioned polyester resin, as the substrate material, has good transparency, it becomes easier to visually identify and inspect the workpiece through the adhesive sheet.

[0033] Furthermore, from the viewpoint of more easily achieving the aforementioned chip suppression effect, for the aforementioned polyester resin, the heat of fusion measured by differential scanning calorimetry at a heating rate of 20°C / min is preferably 5 J / g or more, particularly 10 J / g or more, and even more preferably 15 J / g or more. On the other hand, there is no particular limitation on the upper limit of this heat of fusion; for example, it can be 150 J / g or less, or 100 J / g or less, particularly 70 J / g or less, even more preferably 50 J / g or less, and especially preferably 30 J / g or less. The details of the method for measuring the heat of fusion are as described in the section on the following embodiments.

[0034] (1-1) Polyester resin The specific composition of the above-mentioned polyester resin is not particularly limited as long as it has an alicyclic structure and the polyester resin exhibits the above-mentioned melting heat and other conditions.

[0035] From the viewpoint of more easily obtaining a good chip suppression effect, the alicyclic structure of the above-mentioned polyester resin preferably has 6 or more carbon atoms constituting the rings. Furthermore, it is preferable that the number of carbon atoms is 14 or less, particularly 10 or less. Especially, 6 carbon atoms are preferred. Moreover, the alicyclic structure can be a monocyclic structure formed by one ring, a bicyclic structure formed by two rings, or a structure composed of three or more rings.

[0036] Furthermore, from the viewpoint of easily satisfying the above two conditions, it is preferable that the polyester resin contains a dicarboxylic acid having an alicyclic structure as a monomer unit constituting the polyester resin. Similarly, from the same viewpoint, it is preferable that the polyester resin contains a diol having an alicyclic structure as a monomer unit constituting the polyester resin. Although the polyester resin may contain only one of these dicarboxylic acids and diols, from the viewpoint of more easily satisfying the above conditions, it is preferable that the polyester resin contains both of these dicarboxylic acids and diols.

[0037] The structure of the above-mentioned dicarboxylic acid is not particularly limited as long as it has an alicyclic structure and two carboxyl groups. For example, the dicarboxylic acid can be a structure formed by bonding two carboxyl groups to an alicyclic structure, or it can be a structure formed by further inserting an alkyl group or the like between such an alicyclic structure and the carboxyl group. Preferred examples of such dicarboxylic acids include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-decahydronaphthalenedicarboxylic acid, 1,5-decahydronaphthalenedicarboxylic acid, 2,6-decahydronaphthalenedicarboxylic acid, and 2,7-decahydronaphthalenedicarboxylic acid, among which 1,4-cyclohexanedicarboxylic acid is preferred. This dicarboxylic acid can be a derivative of an alkyl ester or the like. For example, such an alkyl ester derivative can be an alkyl ester with 1 or more but less than 10 carbon atoms. More specific examples include dimethyl esters and diethyl esters, with dimethyl esters being particularly preferred.

[0038] In this embodiment, when the polyester resin, as a constituent monomer unit, includes a dicarboxylic acid having an alicyclic structure, the proportion of the dicarboxylic acid monomer relative to all monomer units constituting the polyester resin is preferably 20 mol% or more, more preferably 25 mol% or more, particularly preferably 30 mol% or more, and further preferably 35 mol% or more. Furthermore, this proportion is preferably 60 mol% or less, more preferably 55 mol% or less, particularly preferably 50 mol% or less, and further preferably 45 mol% or less. Within these ranges, the polyester resin readily exhibits the aforementioned heat of melting, and as a result, the adhesive sheet associated with this embodiment readily achieves a better chip suppression effect.

[0039] Furthermore, in this embodiment, the polyester resin, as a constituent monomer unit, includes dicarboxylic acids having an alicyclic structure. The proportion of dicarboxylic acids having an alicyclic structure relative to the total number of dicarboxylic acids having a cyclic structure constituting the polyester resin is preferably 60% or more, more preferably 70% or more, particularly preferably 80% or more, and further preferably 90% or more. By achieving a proportion of 60% or more, the adhesive sheet related to this embodiment easily achieves a better chip suppression effect. Moreover, there is no particular limitation on the upper limit of this proportion; for example, it can be 100% or less. Furthermore, in addition to dicarboxylic acids having an alicyclic structure, the aforementioned dicarboxylic acids having a cyclic structure also include dicarboxylic acids having an aromatic ring structure.

[0040] The structure of the aforementioned diol is not particularly limited as long as it has an alicyclic structure and two hydroxyl groups. For example, the diol can be formed by bonding two hydroxyl groups to an alicyclic structure, or it can be formed by further inserting an alkyl group between such an alicyclic structure and the hydroxyl group. Preferred examples of such diols include 1,2-cyclohexanediol (especially 1,2-cyclohexanediethanol), 1,3-cyclohexanediol (especially 1,3-cyclohexanediethanol), 1,4-cyclohexanediol (especially 1,4-cyclohexanediethanol), and 2,2-bis-(4-hydroxycyclohexyl)-propane, among which 1,4-cyclohexanediethanol is preferred.

[0041] In this embodiment, when the polyester resin, as a constituent monomer unit, includes a diol having an alicyclic structure, the proportion of the diol monomer relative to all the monomer units constituting the polyester resin is preferably 35 mol% or more, particularly 40 mol% or more, and further preferably 45 mol% or more. Furthermore, this proportion is preferably 65 mol% or less, particularly 60 mol% or less, and further preferably 55 mol% or less. Within these ranges, the polyester resin readily exhibits the aforementioned heat of melting, and as a result, the adhesive sheet associated with this embodiment readily achieves a better chip suppression effect.

[0042] From the viewpoint that the substrate in this embodiment has the desired flexibility, it is preferable that the monomer unit constituting the polyester resin includes a dimer acid obtained by dimerizing unsaturated fatty acids. Here, the number of carbon atoms in the unsaturated fatty acid is preferably 10 or more, particularly 15 or more. Furthermore, the number of carbon atoms is preferably 30 or less, particularly 25 or less. Examples of such dimer acids include a 36-carbon dicarboxylic acid obtained by dimerizing 18-carbon unsaturated fatty acids such as oleic acid and linolenic acid, and a 44-carbon dicarboxylic acid obtained by dimerizing 22-carbon unsaturated fatty acids such as erucic acid. Moreover, in obtaining the above-mentioned dimer acid, a small amount of a trimer acid obtained by trimerizing the above-mentioned unsaturated fatty acids may also be produced. The polyester resin in this embodiment includes the above-mentioned dimer acid, and may also include such a trimer acid.

[0043] In this embodiment, when the polyester resin, as a constituent monomer unit, includes the aforementioned dimer acid, the proportion of the dimer acid relative to all dicarboxylic acid units constituting the polyester resin is preferably 2 mol% or more, particularly 5 mol% or more, and further preferably 10 mol% or more. Furthermore, this proportion is preferably 25 mol% or less, particularly 23 mol% or less, and further preferably 20 mol% or less. Within these ranges, the polyester resin readily acquires the desired softness, and as a result, the adhesive sheet associated with this embodiment achieves excellent extensibility and pick-up properties.

[0044] The polyester resin in this embodiment may also contain monomers other than the dicarboxylic acids, diols, and dimer acids mentioned above as constituent monomer units. Examples of such monomers include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, and sebacic acid; and aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. In addition, it may also contain diol components other than diols having an alicyclic structure. For example, it may also contain ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, decanediol; ethylene oxide adducts of bisphenol A, bisphenol S, etc.; and trimethylolpropane, etc.

[0045] However, in the polyester resin of this embodiment, from the viewpoint of easily achieving excellent chip suppression effect, it is preferable that the monomers having alicyclic structures (as mentioned above, dicarboxylic acids having alicyclic structures and diols having aliphatic structures) are more numerous than monomers having aromatic ring structures. In particular, among the monomer units constituting the polyester resin of this embodiment, the molar ratio of monomer units having aromatic ring structures to monomer units having alicyclic structures is preferably less than 1, more preferably 0.5 or less, more preferably 0.2 or less, more preferably 0.1 or less, more preferably 0.05 or less, more preferably 0.03 or less, more preferably 0.01 or less, especially less than 0.005, further preferably less than 0.001, and most preferably 0.

[0046] The method for manufacturing the polyester resin in this embodiment is not particularly limited. A conventional catalyst can be used to polymerize the above-mentioned monomer components to obtain the polyester resin.

[0047] Relative to all components constituting the substrate of this embodiment, the proportion of polyester resin is preferably 50% or more, particularly 60% or more, and further preferably 70% or more. With the above proportion of 50% or more, the adhesive sheet related to this embodiment becomes more likely to achieve excellent chip suppression effects. Furthermore, there is no particular limitation on the upper limit of the above proportion; for example, it can be 100% or less.

[0048] (1-2) Other components used to make the substrate in this embodiment may also contain other components besides the aforementioned polyester resin. In particular, the material may also contain components that are used in substrates of general adhesive sheets (especially substrates of sheets for general workpiece processing).

[0049] Examples of such components include various additives such as flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers. While there is no particular limitation on the content of such additives, it is preferable to maintain the desired function in the substrate.

[0050] (1-3) Substrate Composition As the layer composition of the substrate in this embodiment, it can be a single layer or multiple layers, as long as it has a layer formed of a material containing the above-mentioned polyester resin (hereinafter, sometimes referred to as "polyester resin layer"). From the viewpoint of reducing manufacturing costs, the substrate in this embodiment is preferably a single layer (polyester resin layer only).

[0051] On the other hand, when there are multiple layers, multiple polyester resin layers can be laminated, or the polyester resin layer can be laminated with other layers. In the latter case, it is preferable that the layer formed by laminating the polyester resin layer as the adhesive layer in the layer structure of the substrate. In this case, it becomes possible to have both the chip suppression effect brought by the polyester resin layer and the desired effect brought by the other layers.

[0052] Furthermore, in order to improve the adhesion to the adhesive layer, surface treatments such as primer treatment, corona treatment, and plasma treatment may be performed on the surface of the substrate where the adhesive layer is deposited.

[0053] (1-4) Method for manufacturing the substrate The method for manufacturing the substrate in this embodiment is not particularly limited as long as a material containing polyester resin is used. For example, melt extrusion methods such as T-die method and circular die method can be used; calendering method; solution method such as dry method and wet method. Among these, melt extrusion method or calendering method is preferred from the viewpoint of manufacturing substrate efficiently.

[0054] When the substrate formed from a single layer is manufactured by melt extrusion, the material of the compound substrate (the material containing the above-mentioned polyester resin) is directly or temporarily made into pellets from the obtained compound and then film-formed using a conventional extruder.

[0055] In addition, when the substrate formed by multiple layers is manufactured by melt extrusion, the components constituting each layer are mixed separately, and the obtained mixture is directly or temporarily made into pellets, and then the multiple layers are extruded simultaneously using a conventional extruder to form a film.

[0056] (1-5) Substrate Properties, etc. The tensile elastic modulus of the substrate in this embodiment at 23°C is preferably 800 MPa or less, particularly 600 MPa or less, and further preferably 500 MPa or less. Furthermore, the tensile elastic modulus is preferably 100 MPa or more, particularly 200 MPa or more, and further preferably 300 MPa or more. With a tensile elastic modulus of 800 MPa or less, the substrate in this embodiment readily possesses the desired softness, and the adhesive sheet associated with this embodiment readily achieves excellent ductility and pick-up properties. Furthermore, with a tensile elastic modulus of 100 MPa or more, the substrate in this embodiment readily possesses moderate strength, and the adhesive sheet becomes readily operable, while also readily allowing for the desired workpiece processing. Details of the method for measuring the tensile elastic modulus are described in the following test examples.

[0057] In this embodiment, the fracture point stress of the substrate at 23°C is preferably 60 MPa or less, particularly 50 MPa or less, and further preferably 40 MPa or less. Furthermore, the fracture point stress is preferably 15 MPa or more, particularly 20 MPa or more, and further preferably 25 MPa or more. With a fracture point stress of 60 MPa or less, the substrate film of this embodiment exhibits better processability. Furthermore, with a fracture point stress of 15 MPa or more, the substrate of this embodiment readily possesses moderate strength, the adhesive sheet exhibits good operability, and it becomes easier to perform desired workpiece processing. Moreover, with a fracture point stress of 15 MPa or more, the substrate film of this embodiment exhibits good ductility. Details of the method for measuring the fracture point stress are described in the following test examples.

[0058] The ductility at break of the substrate in this embodiment at 23°C is preferably 200% or more, more preferably 250% or more, particularly preferably 300% or more, and further preferably 350% or more. With a ductility at break of 200% or more, the substrate in this embodiment readily exhibits the desired elongation, and the adhesive sheet associated with this embodiment readily achieves excellent ductility and pick-up properties. Furthermore, the ductility at break is preferably 800% or less, more preferably 700% or less, particularly preferably 600% or less, and further preferably 500% or less. With a ductility at break of 800% or less, the processability of the substrate is improved, making it easier to manufacture sheets for processing desired workpieces. Details of the method for measuring the ductility at break are described in the following test examples.

[0059] In this embodiment, the thickness of the substrate is preferably 20 μm or more, particularly 40 μm or more, and further preferably 60 μm or more. Furthermore, the thickness of the substrate is preferably 600 μm or less, particularly 300 μm or less, and further preferably 200 μm or less. With a substrate thickness of 20 μm or more, the adhesive sheet easily possesses moderate strength, making it easier to properly support the workpiece fixed to the adhesive sheet. As a result, the occurrence of chipping during cutting can be effectively suppressed. Furthermore, with a substrate thickness of 600 μm or less, the aforementioned fracture ductility is more easily achieved. Moreover, with a substrate film thickness of 600 μm or less, the substrate film exhibits better processability.

[0060] (2) The adhesive layer, as the adhesive constituting the adhesive layer in this embodiment, is not particularly limited as long as it can exert sufficient adhesion to the adhered object (especially for processing workpieces, where the adhesion to the workpiece is sufficient). Examples of adhesives constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives. Among these, from the viewpoint of easily exerting the desired adhesion, acrylic adhesives are preferred.

[0061] The adhesive constituting the adhesive layer in this embodiment may be an adhesive that does not have active energy line curing properties, but it is preferable to use an adhesive that has active energy line curing properties (hereinafter, sometimes referred to as "active energy line curing adhesive"). By making the adhesive layer composed of an active energy line curing adhesive, the adhesive layer is hardened by irradiation with active energy lines, which makes it easier to reduce the adhesion of the adhesive sheet to the adhered object. In particular, when the adhesive sheet related to this embodiment is used as a sheet material for workpiece processing, the processed workpiece becomes easier to separate from the adhesive sheet by irradiation with active energy lines.

[0062] The active energy line curing adhesive constituting the adhesive layer may be a polymer with active energy line curing properties as the main component, or a mixture of an active energy line non-curing polymer (polymer without active energy line curing properties) and a monomer and / or oligomer having at least one active energy line curing group as the main component.

[0063] The polymer with active energy line hardening properties is preferably a (meth)acrylate polymer (hereinafter, sometimes referred to as "active energy line hardening polymer") having an active energy line hardening functional group (active energy line hardening group) introduced into its side chain. This active energy line hardening polymer is preferably obtainable by reacting an acrylic copolymer having a functional group-containing monomer unit with a compound containing an unsaturated group having a functional group bonded to its functional group. Furthermore, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. Other similar terms are also used in the same way. Moreover, "polymer" also includes the concept of "copolymer".

[0064] The weight-average molecular weight of the above-mentioned active energy line-curable polymer is preferably 10,000 or more, particularly 150,000 or more, and further preferably 200,000 or more. Furthermore, the weight-average molecular weight is preferably 2.5 million or less, particularly 2 million or less, and further preferably 1.5 million or less. Moreover, the weight-average molecular weight (Mw) in this specification is the converted value of standard polystyrene determined by gel permeation chromatography (GPC method).

[0065] On the other hand, when the active energy line curable adhesive is a mixture of an active energy line non-curable polymer component and a monomer and / or oligomer having at least one active energy line curable group as the main component, the aforementioned acrylic copolymer can be used as the active energy line non-curable polymer component, for example, before the reaction of the compound containing the unsaturated group. Furthermore, the active energy line curable monomer and / or oligomer can be, for example, an ester of polyol and (meth)acrylic acid.

[0066] The weight average molecular weight of the acrylic polymer, which is the non-hardening polymer component of the above-mentioned active energy line, is preferably 10,000 or more, particularly 150,000 or more, and even more preferably 200,000 or more. In addition, the weight average molecular weight is preferably 2.5 million or less, particularly 2 million or more, and even more preferably 1.5 million or less.

[0067] Furthermore, when ultraviolet light is used as the active energy line for curing the active energy line hardening adhesive, it is preferable to add a photopolymerization initiator to the adhesive. In addition, the active energy line non-hardening polymer component or oligomer component, crosslinking agent, etc., may also be added to the adhesive.

[0068] In this embodiment, the thickness of the adhesive layer is preferably 1 μm or more, particularly 2 μm or more, and further preferably 3 μm or more. Furthermore, the thickness of the adhesive layer is preferably 50 μm or less, particularly 40 μm or less, and further preferably 30 μm or less. With an adhesive layer thickness of 1 μm or more, the adhesive sheet associated with this embodiment easily exhibits the desired adhesive properties. Furthermore, with an adhesive layer thickness of 50 μm or less, the cured adhesive layer can be easily separated from the adhered object.

[0069] (3) The adhesive sheet related to the peeling sheet in this embodiment can also be peeled off on the area layer for the purpose of protecting the surface during the period when the side opposite to the substrate in the adhesive layer (hereinafter, sometimes referred to as the "adhesive surface") is attached to the object.

[0070] The composition of the aforementioned release sheet is arbitrary. For example, a plastic film may be peeled off using a release agent or the like. Specific examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene. As the release agent, silicone-based, fluorine-based, and long-chain alkane-based agents may be used. Among these, silicone-based agents, which are inexpensive and provide stable performance, are preferred.

[0071] There are no particular restrictions on the thickness of the above-mentioned release sheet. For example, it can be above 20μm and below 250μm.

[0072] (4) In other adhesive sheets related to this embodiment, an adhesive layer may also be laminated on the side of the adhesive layer opposite to the substrate. In this case, the adhesive sheet related to this embodiment can be used as a die-grain bonding sheet. The workpiece is attached to the side of the adhesive layer opposite to the adhesive layer of the sheet, and by cutting the workpiece together with the adhesive layer, a wafer with a laminated individual adhesive layer can be obtained. The wafer can be easily fixed to the object on which the wafer is mounted by this individual adhesive layer. As for the material constituting the adhesive layer, it is preferable to use a material containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, or a material containing a B-stage (semi-cured) thermosetting adhesive component.

[0073] Furthermore, in the adhesive sheet of this embodiment, a protective film forming layer can also be deposited on the adhesive surface of the adhesive layer. In this case, the adhesive sheet of this embodiment can be used as a sheet for both protective film formation and cutting. A workpiece is attached to the side of the protective film forming layer opposite to the adhesive layer, and by cutting the workpiece along with the protective film forming layer, a wafer with a laminated, individually laminated protective film forming layer can be obtained. It is preferable to use a workpiece on which a circuit is formed on one side. In this case, typically, the protective film forming layer is deposited on the side opposite to the side where the circuit is formed. The individually laminated protective film forming layer, by curing it at a specific time, can form a sufficiently durable protective film on the wafer. It is preferable that the protective film forming layer is formed from an uncured curable adhesive.

[0074] 2. Method for manufacturing adhesive sheet There is no particular limitation on the method for manufacturing adhesive sheet related to this embodiment. For example, it is preferable to obtain adhesive sheet by forming an adhesive layer on a release sheet and then laminating a single side of a substrate on the side of the adhesive layer opposite to the release sheet.

[0075] The formation of the adhesive layer described above can be carried out by conventional methods. For example, a coating liquid containing an adhesive composition for forming the adhesive layer, and further containing a solvent or dispersant as needed, is prepared. Then, the coating liquid is applied to the peelable surface of the release sheet (hereinafter, sometimes referred to as the "release surface"). Next, the adhesive layer is formed by drying the resulting coating film.

[0076] The coating of the above-mentioned coating liquid can be carried out by conventional methods, such as bar coating, blade coating, roller coating, flap coating, die coating, gravure coating, etc. Furthermore, as long as the coating liquid is suitable for coating, its state is not particularly limited; it may contain components used to form the adhesive layer as a solute, or it may contain components used as a dispersion. In addition, the release sheet can also be used as a process material for release, and can also protect the adhesive layer during the period until it is adhered to the substrate.

[0077] When the adhesive component used to form the adhesive layer contains the aforementioned crosslinking agent, it is preferable to change the aforementioned drying conditions (temperature, time, etc.) or to additionally perform a heat treatment to allow the polymer component in the coating film to undergo a crosslinking reaction with the crosslinking agent, thereby forming a crosslinked structure in the adhesive layer at a desired density. Furthermore, in order to ensure that the aforementioned crosslinking reaction proceeds sufficiently, after the adhesive layer and the substrate are bonded together, a curing process may be carried out, for example, by allowing the mixture to stand at 23°C and 50% relative humidity for several days.

[0078] 3. Method of Using the Adhesive Sheet While the adhesive sheet of this embodiment can be used for various purposes similar to general adhesive sheets, it is particularly suitable for use as a workpiece processing sheet in the processing of workpieces such as semiconductor wafers. In this case, after the adhesive surface of the adhesive sheet of this embodiment is attached to the workpiece, the workpiece can be processed on the adhesive sheet. For this processing, the adhesive sheet of this embodiment can be used as a workpiece processing sheet for back-grinding, cutting, stretching, and wafer picking. Examples of workpieces include semiconductor wafers, semiconductor components such as semiconductor packages, and glass components such as glass plates.

[0079] As described above, the adhesive sheet of this embodiment can effectively suppress the generation of cutting chips when used for cutting with a rotating disc cutter. Therefore, the adhesive sheet of this embodiment is particularly suitable as a cutting sheet among the workpiece machining sheets described above.

[0080] Furthermore, when the adhesive sheet related to this embodiment has the above-mentioned adhesive layer, the adhesive sheet can be used as a cutting-grain bonding sheet. Moreover, when the adhesive sheet related to this embodiment has the above-mentioned protective film forming layer, the adhesive sheet can be used as a sheet for both protective film formation and cutting.

[0081] Furthermore, when the adhesive layer in the adhesive sheet related to this embodiment is composed of the aforementioned active energy line hardening adhesive, it is preferable to irradiate it with the active energy line as described above during use. In other words, when processing a workpiece on the adhesive sheet and separating the processed workpiece from the adhesive sheet, it is preferable to irradiate the adhesive layer with the active energy line before separation. In this way, the adhesive layer hardens, the adhesion of the adhesive sheet to the processed workpiece is significantly reduced, and the separation of the processed workpiece becomes easier.

[0082] The embodiments described above are for ease of understanding of the present invention and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments encompass all design changes and equivalents to the scope of the present invention. [Examples]

[0083] Hereinafter, although the present invention will be further described in detail by way of examples, the scope of the present invention is not limited to these examples.

[0084] [Example 1] (1) Preparation of the substrate In a reactor equipped with a stirrer, distillation tube and a vacuum device, 12.90 kg of dimethyl 1,4-cyclohexanedicarboxylate (98% trans) , 11.47 kg of 1,4-cyclohexanediethanol , 0.3 kg of ethylene glycol and 0.11 kg of ethylene glycol solution containing 10% manganese acetate tetrahydrate were poured in. The mixture was heated to 200°C under a nitrogen flow and then heated to 230°C over 1 hour. After maintaining this temperature for 2 hours to carry out the transesterification reaction, 10.30 kg of dimer acid from erucic acid (carbon number 44, manufactured by Croda, product name "PRIPOL1004") and 0.11 kg of ethylene glycol solution containing 10% trimethyl phosphate were added to the reaction system, and then the esterification reaction was carried out at 230°C for 1 hour. Next, after adding 300 ppm of germanium dioxide as a polymerization catalyst, the pressure was reduced to below 133 Pa for 1 hour. During this period, the internal temperature was increased from 230°C to 270°C, and the mixture was stirred under a high vacuum below 133 Pa until a specific viscosity was achieved, thus initiating the polymerization reaction. The resulting polymer was extruded into strips in water, cut into pellets, and then...

[0085] The polyester resin pellets obtained thereby are dried at 85°C for at least 4 hours and then fed into the feed hopper of a single-shaft extruder equipped with a T-die. Then, the resin is extruded from the T-die in a melt-mixed state under conditions of a roller temperature of 220°C and a die temperature of 220°C, and cooled by a cooling roller to obtain a sheet-like substrate with a thickness of 80 μm.

[0086] Furthermore, as a monomer constituting the resin, the aforementioned polyester resin comprises approximately 50 mol% of 1,4-cyclohexanediethanol, approximately 40.5 mol% of dimethyl 1,4-cyclohexanedicarboxylate, and 9.5 mol% of a dimer acid derived from erucic acid. In addition, the proportion of the dimer acid relative to all dicarboxylic acid units constituting the aforementioned polyester resin is 19.1 mol%. Furthermore, the heat of fusion of the aforementioned polyester resin, measured by the following method, is 20 J / g.

[0087] (2) The adhesive component was prepared by polymerizing 95 parts by mass of n-butyl acrylate and 5 parts by mass of acrylic acid by solution polymerization to obtain a (meth)acrylate polymer. The weight average molecular weight (Mw) of this acrylic polymer was determined by the following method and was 500,000.

[0088] Mix 100 parts by weight (converted to solids, the same below) of the (meth)acrylate polymer obtained as described above, 120 parts by weight of the urethane acrylate oligomer (Mw: 8,000), 5 parts by weight of the isocyanate crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L"), and 4 parts by weight of the photopolymerization initiator (manufactured by IGM Resins B.V., product name "Omnirad 184") to obtain an energy-ray curable adhesive composition.

[0089] (3) Formation of the adhesive layer: The adhesive composition obtained in step (2) above is coated on one side of a 38 μm thick polyethylene terephthalate film, which is the release treatment side of a release sheet (manufactured by LINTEC Corporation, product name "SP-PET381031") that has been released by a silicone-based release agent. The resulting coating is dried at 100°C for 1 minute. In this way, a laminate with an adhesive layer of 10 μm thickness is obtained on the release surface of the release sheet.

[0090] (4) The adhesive sheet is made by bonding the side of the substrate obtained in step (1) above with the side of the adhesive layer in the laminate obtained in step (3) above.

[0091] Here, the heat of fusion of the above-mentioned polyester resin was measured using a differential scanning calorimeter (DSC, manufactured by TA Instruments, product name "DSC Q2000") based on JIS K 7121:2012.

[0092] Specifically, firstly, the temperature is increased from room temperature to 250°C at a heating rate of 20°C / min, maintained at 250°C for 10 minutes, and then decreased to -60°C at a cooling rate of 20°C / min, maintained at -60°C for 10 minutes. Afterward, the temperature is increased again to 250°C at a heating rate of 20°C / min, a DSC curve is obtained, and the melting point is determined.

[0093] Furthermore, the above-mentioned weight-average molecular weight (Mw) is the converted standard polystyrene weight-average molecular weight determined using a gel permeation chromatography (GPC) apparatus under the following conditions (GPC determination). <Determination Conditions> • Measuring apparatus: Tosoh Corporation, HLC-8320 • GPC column (passing in the following order): Tosoh Corporation, TSK gel superH-H, TSK gel superHM-H, TSK gel superH2000 • Measuring solvent: tetrahydrofuran • Measuring temperature: 40°C

[0094] [Comparative Example 1] Except for using a polyvinyl chloride resin sheet with a thickness of 80 μm as the substrate, the adhesive sheet was obtained in the same manner as in Example 1. Furthermore, the heat of fusion of the polyvinyl chloride resin, measured by the above method, was 0 J / g.

[0095] [Comparative Example 2] Except for using a substrate (80 μm thick) composed of ethylene-methacrylic acid copolymer (EMAA) with one side surface treated by electron beam irradiation as the substrate, and laminating an adhesive layer on the electron beam irradiated surface of the substrate, the adhesive sheet was obtained in the same manner as in Example 1. Furthermore, the heat of fusion of the aforementioned ethylene-methacrylic acid copolymer, measured by the above method, was 81 J / g.

[0096] [Comparative Example 3] Except for using a substrate (80 μm thick) made of EMAA with one side surface treated by electron beam irradiation as the substrate, and laminating an adhesive layer on the electron beam irradiated surface of the substrate, the adhesive sheet was obtained in the same manner as in Example 1. Furthermore, the electron beam irradiation dose of the substrate used in Comparative Example 3 was twice that of the substrate used in Comparative Example 2. In addition, the heat of fusion of the above-mentioned ethylene-methacrylic acid copolymer, measured by the above method, was 79 J / g.

[0097] [Comparative Example 4] Except for using a resin sheet with a thickness of 80 μm made of a glycol-modified polyester resin having the structure represented by the following general formula (1) as a substrate, the adhesive sheet was obtained in the same manner as in Example 1. Furthermore, the heat of fusion of the above-mentioned glycol-modified polyester resin, measured by the above method, was 0 J / g. [Chemical 1]

[0098] [Comparative Example 5] Except for using a resin sheet with a thickness of 80 μm made of an amorphous polyester resin having the structure represented by the following general formula (2) as a substrate, the adhesive sheet was obtained in the same manner as in Example 1. Furthermore, the heat of fusion of the aforementioned amorphous polyester resin, measured by the above method, was 0 J / g. [Chemical 2]

[0099] [Test Example 1] (Determination of Tensile Properties of Substrate) The substrates prepared in the Examples and Comparative Examples were cut into test pieces of 15mm × 150mm. The 150mm edge was parallel to the MD direction (the flow direction during substrate manufacturing), and the 15mm edge was parallel to the TD direction (perpendicular to the MD direction) of the substrate film. Then, the tensile elastic modulus, elongation at break, and stress at the point of break were measured for this test piece according to JIS K7127:1999.

[0100] Specifically, the test piece was subjected to a tensile test in a tensile testing machine (manufactured by Shimadzu Corporation, product name "AUTOGRAPH AG-Xplus 100N"), with the distance between the clamps set to 100 mm. The test piece was stretched in the MD direction of the substrate film at a speed of 200 mm / min in an environment of 23°C. The tensile elastic modulus (MPa), elongation at break (%), and stress at the point of break (MPa) were measured. The results are shown in Table 1.

[0101] [Experimental Example 2] (Determination of the number of cutting chips) The release sheet was peeled off from the adhesive sheet manufactured in the Examples and Comparative Examples. The exposed adhesive layer was then attached to one side of a 40 μm thick silicon wafer. A cutting ring frame was then attached to the edge of the exposed surface of the adhesive sheet (the position not overlapping with the silicon wafer). Next, the silicon wafer was cut using a cutting machine (manufactured by Disco Corporation, product name "DFD6362") under the following conditions: • Workpiece (attached object): Silicon wafer • Workpiece size: 6 inches in diameter, 40 μm thick • Cutting blade: Manufactured by Disco Corporation, product name "27HECC", diamond blade • Blade rotation speed: 50,000 rpm • Cutting speed: 100 mm / sec • Cutting depth: 20 μm from the substrate surface • Cutting size: 8 mm × 8 mm.

[0102] After dicing, the silicon wafers, individually waferized, are attached to the bonding pad. The number of chips generated on the kerf (the cutting path created by the cutting edge) is counted using an electron microscope (manufactured by Keyence Corporation, product name "VHX-5000", magnification: 500x). At this time, there are multiple kerfs in both the vertical and horizontal directions. The number of chips on the three paths near the center in the vertical direction and the three paths near the center in the horizontal direction are counted. The counting results are shown in Table 1.

[0103] [Table 1] Substrate Tensile properties of the substrate Number of cutting chips (pieces) resin Electron beam irradiation Tensile elastic modulus (MPa) Fracture ductility (%) Failure point stress (MPa) type Heat of fusion (J / g) Example 1 Polyester resin 20 none 400 390 32 72 Comparative Example 1 Polyvinyl chloride resin 0 none 328 290 28 202 Comparative Example 2 Ethylene-methacrylic acid copolymer 81 have 115 353 26 272 Comparative Example 3 Ethylene-methacrylic acid copolymer 79 Yes (twice that of Comparative Example 2) 138 223 26 188 Comparative Example 4 Diol-modified polyester resin 0 none 1570 380 59 241 Comparative Example 5 Amorphous polyester resin 0 none 1465 280 69 153

[0104] As can be clearly seen from Table 1, the adhesive sheet manufactured in the examples effectively suppresses the generation of cutting chips during cutting. [Industry Applicability]

[0105] The adhesive sheet of the present invention is suitable for use as a workpiece processing sheet for processing workpieces such as semiconductor wafers. [Simplified Explanation of the Diagram]

[0107] None.

Claims

1. A sheet material for workpiece processing, comprising a substrate and an adhesive layer laminated on one side of the substrate, characterized in that: the substrate is formed of a material containing polyester resin, the polyester resin has an alicyclic structure, and the heat of fusion measured by differential scanning calorimetry at a heating rate of 20°C / min is 2 J / g or more; the polyester resin, as a monomer unit constituting the polyester resin, comprises a dimer acid formed by dimerizing an unsaturated fatty acid, the unsaturated fatty acid having 10 or more carbon atoms and 30 or less; the sheet material for workpiece processing is a cutting sheet for cutting using a rotating disc cutter.

2. The sheet material for processing the workpiece as described in claim 1, wherein, The aforementioned polyester resin, as a monomer unit constituting the polyester resin, comprises a dicarboxylic acid having the aforementioned alicyclic structure.

3. The sheet material for processing the workpiece as described in claim 1, wherein, The aforementioned polyester resin, as a monomer unit constituting the polyester resin, is a diol containing the aforementioned alicyclic structure.

4. The sheet material for processing the workpiece as described in claim 1, wherein, The above-mentioned alicyclic structures are those in which the number of carbon atoms constituting the ring is 6 or more but less than 14.

5. The sheet material for processing the workpiece as described in claim 1, wherein, The proportion of the dimer acid, which is a monomer unit constituting the polyester resin, is 2 mol% or more and 25 mol% or less, relative to all dicarboxylic acids that constitute the monomer unit constituting the polyester resin.

6. The sheet material for processing the workpiece as described in claim 1, wherein, The tensile elastic modulus of the above-mentioned substrate at 23°C is above 100MPa and below 800MPa.

7. The sheet material for processing the workpiece as described in claim 1, wherein, The above-mentioned substrate has a fracture ductility of more than 200% and less than 800% at 23°C.

8. The sheet material for processing the workpiece as described in claim 1, wherein, The thickness of the aforementioned substrate is 20 μm or more and 600 μm or less.

9. The sheet material for processing the workpiece as described in claim 1, wherein, The adhesive layer described above is composed of an acrylic adhesive.