Sheet for workpiece processing and method for manufacturing processed workpiece

Abstract

The technical problem of the present invention is to provide a workpiece processing sheet that can well balance operability and expandability even after heating. As a solution, first, the present invention provides a workpiece processing sheet, which comprises a substrate and an adhesive layer laminated on one side of the substrate, the Young's modulus of the substrate at 23°C after heating at 120°C for 4 hours is 2000 MPa or less, and the storage modulus E' of the substrate at 120°C is 33 MPa or more. Second, the present invention provides a workpiece processing sheet, which comprises a substrate and an adhesive layer laminated on one side of the substrate, the elongation at break of the substrate at 23°C after heating at 120°C for 4 hours is 100% or more, and the storage modulus E' of the substrate at 120°C is 33 MPa or more.

Description

Technical Field

[0001] The present invention relates to a workpiece processing sheet that can be suitably used for processing workpieces such as semiconductor wafers, and in particular to a workpiece processing sheet that can be suitably used in a workpiece processing method including a step of heating the workpiece processing sheet in a state where it is stacked with a workpiece before or after processing. Background Art

[0002] The method for manufacturing a semiconductor device generally includes: a dicing step of singulating (cutting) a semiconductor wafer as a workpiece on a workpiece processing sheet to obtain a plurality of semiconductor chips; and a picking step of removing (picking up) the obtained semiconductor chips one by one from the workpiece processing sheet.

[0003] In the above-mentioned picking-up process, in order to facilitate the picking-up of semiconductor chips, the following operation is sometimes performed: the semiconductor chips are pushed up one by one from the surface of the workpiece processing sheet opposite to the surface on which the semiconductor chips are stacked. In particular, in the above-mentioned picking-up process, in order to suppress the collision of semiconductor chips with each other during picking up and to facilitate picking up, the following operation is usually performed: the workpiece processing sheet is stretched (expanded) to separate the semiconductor chips from each other. Therefore, the workpiece processing sheet is required to have excellent flexibility to enable good expansion.

[0004] In recent years, there has been an increasing number of cases where a workpiece processing sheet is heated in a state where individual semiconductor chips are stacked. For example, the semiconductor chips on the workpiece processing sheet are subjected to evaporation, sputtering, baking for dehumidification, etc., or when the semiconductor chips are used in a high temperature environment, a heating test is performed to confirm the reliability in the high temperature environment. In such a treatment accompanied by heating, the workpiece processing sheet may sometimes be fused to the device due to heating, and at this time, there is a problem that the workpiece processing sheet cannot be transported to the next process. Therefore, the workpiece processing sheet provided for the process accompanied by heating is also required to have a specified heat resistance.

[0005] As an example of a sheet for workpiece processing having heat resistance, Patent Document 1 discloses a heat-resistant cutting tape or sheet, which is formed by providing an adhesive layer having a thermal weight loss rate of less than 2% when the temperature is increased from room temperature to 200°C at a heating rate of 2°C / min on at least one surface of a substrate having a glass transition temperature of 70°C or above, wherein the adhesive layer is composed of an energy ray-curable adhesive having a specified composition, and the adhesive strength after a treatment including heating shows a specified value.

[0006] In addition, as another example of a workpiece processing sheet having heat resistance, Patent Document 2 discloses a heat-resistant adhesive sheet comprising: a substrate having a predetermined heat shrinkage rate; and an adhesive layer having a predetermined composition disposed on the substrate. Furthermore, Patent Document 3 discloses a heat-resistant adhesive sheet comprising: a substrate having a predetermined heat shrinkage rate and a linear expansion coefficient; and an adhesive layer having a predetermined composition disposed on the substrate.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent No. 4781185

[0010] Patent Document 2: International Publication No. 2015 / 174381

[0011] Patent Document 3: International Publication No. 2014 / 199993 Summary of the invention

[0012] Technical Problems to be Solved by the Invention

[0013] However, although the workpiece processing sheets disclosed in Patent Documents 1 to 3 have a predetermined heat resistance, they are not sufficiently flexible after being heated. In particular, when the heating time is a long time such as several hours, the flexibility is seriously impaired. Thus, it is difficult for conventional semiconductor processing sheets to have both excellent operability and excellent expansibility after heating. If one characteristic is prioritized, the other characteristic is easily impaired.

[0014] The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide a workpiece processing sheet that can achieve good balance between operability and expandability even after heating.

[0015] Technical means to solve technical problems

[0016] In order to achieve the above-mentioned purpose, first, the present invention provides a workpiece processing sheet, which comprises a substrate and an adhesive layer laminated on one side of the substrate, and the workpiece processing sheet is characterized in that the Young's modulus of the substrate at 23°C after heating at 120°C for 4 hours is less than 2000 MPa, and the storage modulus E' of the substrate at 120°C is greater than 33 MPa (Invention 1).

[0017] Since the workpiece processing sheet of the above invention (Invention 1) satisfies the above Young's modulus and storage elastic modulus E', the workpiece processing sheet has excellent handleability even after heating and also has excellent expandability.

[0018] Second, the present invention provides a sheet for workpiece processing, which comprises a substrate and an adhesive layer laminated on one side of the substrate, wherein the sheet for workpiece processing is characterized in that the elongation at break of the substrate at 23°C after heating at 120°C for 4 hours is 100% or more, and the storage modulus E' of the substrate at 120°C is 33 MPa or more (Invention 2).

[0019] Since the workpiece processing sheet of the above invention (Invention 2) satisfies the above-mentioned elongation at break and storage elastic modulus E', the sheet has excellent handleability even after heating and also excellent expandability.

[0020] In the above inventions (Inventions 1 and 2), it is preferred to simultaneously satisfy the following conditions: the Young's modulus of the substrate at 23°C after heating at 120°C for 4 hours is less than 2000 MPa; and the elongation at break of the substrate at 23°C after heating at 120°C for 4 hours is greater than 100% (Invention 3).

[0021] In the above inventions (Inventions 1 to 3), it is preferred that the thickness of the substrate is 50 μm or more and 200 μm or less (Invention 4).

[0022] In the above inventions (Inventions 1 to 4), it is preferred that the adhesive layer is formed of an active energy ray-curable adhesive (Invention 5).

[0023] In the above inventions (Inventions 1 to 5), it is preferred that the workpiece processing sheet is used in a workpiece processing method having a heating step in a state where the workpiece before or after processing is stacked on the surface of the adhesive layer opposite to the substrate (Invention 6).

[0024] Third, the present invention provides a method for manufacturing a processed workpiece, characterized in that it comprises: a bonding step of bonding the workpiece to the surface of the adhesive layer of the workpiece processing sheet (Inventions 1 to 6) which is opposite to the substrate; a cutting step of obtaining a processed workpiece by singulating the workpiece by cutting the workpiece on the workpiece processing sheet; a heating step of subjecting the processed workpiece to a heating treatment in a state of being bonded to the workpiece processing sheet; and a picking up step of picking up the processed workpiece from the workpiece processing sheet (Invention 7).

[0025] Effects of the Invention

[0026] The workpiece processing sheet of the present invention can achieve good balance between handleability and expandability even after heating. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present invention will be described.

[0028] The workpiece processing sheet according to the present embodiment includes a base material and an adhesive layer laminated on one surface of the base material.

[0029] In the workpiece processing sheet of the present embodiment, the storage modulus E' of the substrate at 120°C is 33 MPa or more. By making the substrate show such a storage modulus E', even when the workpiece processing sheet of the present embodiment is provided to a heating process, it is possible to suppress the substrate from being fused to a device, etc. As a result, the heated workpiece processing sheet can be removed from a device for heat treatment, etc., and can be well conveyed to the next process. That is, the workpiece processing sheet of the present embodiment has excellent operability even when heated. From the perspective of achieving better operability, the above-mentioned storage modulus E' is preferably 100 MPa or more, and particularly preferably 110 MPa or more.

[0030] On the other hand, for the upper limit of the above-mentioned storage modulus E', although not particularly limited, for example, preferably below 500MPa, particularly preferably below 300MPa, more preferably below 200MPa. In addition, the above-mentioned storage modulus E' refers to the average value of the storage modulus E' obtained by measuring the MD direction (transmission direction when manufacturing substrate) and CD direction (direction orthogonal to the MD direction) of the substrate, respectively, and the details of its determination method are shown in the test examples described later. In addition, although the above-mentioned storage modulus E' is the value of the substrate itself, the storage modulus E' of the workpiece processing sheet formed by stacking the adhesive layer on the substrate is also the value almost the same as the storage modulus E' of the substrate itself.

[0031] In addition, in the workpiece processing sheet of the present embodiment, it is preferred that the Young's modulus of the substrate at 23°C after heating at 120°C for 4 hours is 2000MPa or less. By making the substrate show such a Young's modulus, even when the workpiece processing sheet of the present embodiment is supplied to the heating process, good flexibility can be exerted. Thus, after the heat treatment, the workpiece processing sheet can be well expanded. From the perspective of achieving better expansibility, the above-mentioned Young's modulus is more preferably less than 1000MPa, particularly preferably less than 600MPa, and further preferably less than 500MPa.

[0032] On the other hand, for the lower limit of the above-mentioned Young's modulus, from the perspective of realizing more excellent flexibility, especially effectively preventing the tearing of the sheet when expanding, preferably more than 50MPa, particularly preferably more than 300MPa, more preferably more than 400MPa.In addition, the above-mentioned Young's modulus refers to the mean value of the Young's modulus obtained by measuring the MD direction and CD direction of the substrate respectively, and the details of its measuring method are shown in the test examples described later.In addition, although the above-mentioned Young's modulus is the value of the substrate itself, the Young's modulus of the workpiece processing sheet formed by stacking the adhesive layer on the substrate is also the value almost the same as the Young's modulus of the substrate itself.

[0033] In addition, in the workpiece processing sheet of the present embodiment, it is also preferred that the elongation at break of the substrate at 23°C after heating at 120°C for 4 hours is 100% or more. By making the substrate show such an elongation at break, even when the workpiece processing sheet of the present embodiment is provided to a heating process, good flexibility can be exerted. Thus, after the heat treatment, the workpiece processing sheet can be well expanded. From the perspective of achieving better expansibility, the above-mentioned elongation at break is particularly preferably 150% or more, and more preferably 200% or more.

[0034] On the other hand, the upper limit of the elongation at break is preferably 750% or less, particularly preferably 400% or less. In addition, the elongation at break is the average value of the elongation at break obtained by measuring the MD direction and CD direction of the substrate, respectively, and the details of the measuring method are shown in the test examples described later. In addition, although the elongation at break is the value of the substrate itself, the elongation at break of the workpiece processing sheet formed by laminating the adhesive layer on the substrate is usually almost the same as the elongation at break of the substrate itself.

[0035] In the workpiece processing sheet of the present embodiment, by making the substrate satisfy the above-mentioned storage modulus E' and at least one of the above-mentioned Young's modulus and elongation at break, it is possible to take into account both excellent operability and excellent expansibility after heating. However, from the perspective of taking into account excellent operability and excellent expansibility in a higher dimension, it is preferred that the substrate satisfies the above-mentioned storage modulus E' and at the same time satisfies the above-mentioned Young's modulus and elongation at break.

[0036] 1. Composition of workpiece processing sheets

[0037] (1) Base material

[0038] The composition of the substrate of this embodiment is not limited as long as it exhibits the above-mentioned storage modulus E' and at least one of the above-mentioned Young's modulus and elongation at break. From the perspective of facilitating the achievement of these physical properties, the substrate is preferably made of at least one of polybutylene terephthalate and thermoplastic polyester elastomer.

[0039] In addition, examples of materials for the substrate other than the above include polyester films such as polyethylene terephthalate films; polyethylene films such as low-density polyethylene (LDPE) films, linear low-density polyethylene (LLDPE) films, and high-density polyethylene (HDPE) films; polyolefin films such as polypropylene films, polybutylene films, polybutadiene films, polymethylpentene films, ethylene-norbornene copolymer films, and norbornene resin films; ethylene copolymer films such as ethylene-vinyl acetate copolymer films, ethylene-(meth)acrylic acid copolymer films, and ethylene-(meth)acrylic acid ester copolymer films; polyvinyl chloride films such as polyvinyl chloride films and vinyl chloride copolymer films; polystyrene films; polyetherimide films; polyetheretherketone films; fluororesin films, etc. In addition, the substrate may be a modified film such as a crosslinked film or ionomer film of the above films.

[0040] The substrate of the present embodiment may be a film formed of one of the above materials, or may be a laminated film in which two or more of the above materials are combined.

[0041] In order to improve the adhesion with the adhesive layer, the surface of the laminated adhesive layer of the substrate may be subjected to a surface treatment based on an oxidation method or a convexoconcave method, or a primer treatment. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromating treatment (wet), flame treatment, hot air treatment, ozone, ultraviolet irradiation treatment, and the like. In addition, examples of the convexoconcave method include sandblasting, thermal spraying treatment, and the like.

[0042] The substrate of this embodiment may contain various additives such as colorants, flame retardants, plasticizers, antistatic agents, lubricants, fillers, etc. When the adhesive layer contains a material that is cured by active energy rays, the substrate preferably has transparency to the active energy rays.

[0043] As long as the substrate having the above-mentioned physical properties can be manufactured, there is no particular limitation on the method for manufacturing the substrate of the present embodiment. For example, the substrate can be manufactured by a melt extrusion method such as a T-die method, a circular die method, a calendering method, a dry method, a wet method, or other solution method by molding the above-mentioned material into a sheet.

[0044] The thickness of the substrate in this embodiment is preferably 50 μm or more and 200 μm or less. When the thickness of the substrate is within this range, the substrate is likely to satisfy the above-mentioned physical properties, thereby easily achieving excellent handling properties and excellent expandability in a higher dimension.

[0045] (2)Adhesive layer

[0046] As the adhesive constituting the adhesive layer of the present embodiment, there is no particular limitation as long as it can exert sufficient adhesion to the adherend (especially sufficient adhesion to the workpiece for workpiece processing). As examples of the adhesive constituting the adhesive layer, acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, etc. can be cited. Among them, acrylic adhesives are preferably used from the perspective of easily exerting the required adhesion.

[0047] The adhesive constituting the adhesive layer of the present embodiment may be an adhesive that does not have active energy ray curing properties, but is preferably an adhesive that has active energy ray curing properties (hereinafter, sometimes referred to as "active energy ray curing adhesive"). By constituting the adhesive layer with an active energy ray curing adhesive, the adhesive layer can be cured by irradiation with active energy rays, and the adhesion of the workpiece processing sheet to the adherend can be easily reduced. In particular, the processed workpiece can be easily separated from the workpiece processing sheet by irradiation with active energy rays.

[0048] As the active energy ray curable adhesive constituting the adhesive layer, it can be a polymer having active energy ray curability as the main component, or a mixture of a non-active energy ray curable polymer (a polymer not having active energy ray curability) and a monomer and / or oligomer having at least one active energy ray curable group as the main component. In addition, the active energy ray curable adhesive can also be a mixture of a polymer having active energy ray curability and a monomer and / or oligomer having at least one active energy ray curable group.

[0049] Preferably, the above-mentioned active energy ray-curable polymer is a (meth) acrylate polymer (hereinafter sometimes referred to as "active energy ray-curable polymer") having an active energy ray-curable functional group (active energy ray-curable group) introduced into the side chain. The active energy ray-curable polymer is preferably obtained by reacting an acrylic polymer having a functional group-containing monomer unit with an unsaturated group-containing compound, wherein the unsaturated group-containing compound has a functional group bonded to the functional group of the acrylic polymer. In addition, in this specification, (meth) acrylic acid refers to acrylic acid and methacrylic acid. Other similar terms are also the same. Furthermore, the concept of "copolymer" is also included in "polymer".

[0050] The acrylic polymer having a functional group-containing monomer unit may be a polymer obtained by polymerizing other monomers together with the functional group-containing monomer. As such a functional group-containing monomer and other monomers, and the unsaturated group-containing compound, known compounds may be used, for example, compounds disclosed in International Publication No. 2018 / 084021.

[0051] The weight average molecular weight of the above-mentioned active energy ray curable polymer is preferably 10,000 or more, particularly preferably 150,000 or more, and further preferably 200,000 or more. In addition, the weight average molecular weight is preferably 1.5 million or less, particularly preferably 1 million or less. In addition, the weight average molecular weight (Mw) in this specification is a value calculated based on standard polystyrene measured by gel permeation chromatography (GPC method).

[0052] As the inactive energy ray-curable polymer component, for example, the acrylic polymer before being reacted with the unsaturated group-containing compound can be used.

[0053] The weight average molecular weight of the acrylic polymer as the inactive energy ray-curable polymer component is preferably 10,000 or more, particularly preferably 150,000 or more, and further preferably 200,000 or more. Also, the weight average molecular weight is preferably 1.5 million or less, particularly preferably 1 million or less.

[0054] In addition, as the above-mentioned monomer and / or oligomer having at least one active energy ray-curable group, for example, esters of polyols and (meth)acrylic acid can be used.

[0055] When ultraviolet rays are used as the active energy rays for curing the active energy ray-curable adhesive, a photopolymerization initiator is preferably added to the adhesive. In addition, a non-active energy ray-curable polymer component or oligomer component, a crosslinking agent, etc. may be added to the adhesive.

[0056] The thickness of the adhesive layer of the present embodiment is preferably 5 μm or more and 30 μm or less. By making the thickness of the adhesive layer within this range, the workpiece processing sheet of the present embodiment is easy to exert the required adhesion. In addition, when the adhesive layer is formed by an active energy ray curable adhesive, by making the thickness within the above range, the workpiece can be fully fixed before curing, and the processed workpiece can be easily separated from the adhesive layer after curing.

[0057] (3) Peel sheet

[0058] In the workpiece processing sheet of the present embodiment, before attaching the workpiece to the surface of the adhesive layer opposite to the substrate (hereinafter sometimes referred to as “adhesive surface”), a release sheet may be laminated on the surface for the purpose of protecting the surface.

[0059] The release sheet may be of any type, and may be a release sheet obtained by subjecting a plastic film to a release treatment using a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene. As the release agent, silicones, fluorines, and long-chain alkyls may be used, and silicones are preferred because they are inexpensive and can provide stable performance.

[0060] The thickness of the release sheet is not particularly limited, and may be, for example, 20 μm or more and 250 μm or less.

[0061] (4) Others

[0062] In the workpiece processing sheet of the present embodiment, an adhesive layer can also be stacked on the surface of the adhesive layer on the opposite side to the substrate. In this case, the workpiece processing sheet of the present embodiment can be used, for example, as a cutting-die bonding sheet. In the sheet, by attaching the workpiece to the surface of the adhesive layer on the opposite side to the adhesive layer, and cutting the adhesive layer together with the workpiece, a chip stacked with a singulated adhesive layer can be obtained. The singulated adhesive layer can be used to easily fix the chip on the object on which the chip is mounted. As the material constituting the above-mentioned adhesive layer, it is preferred 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.

[0063] In addition, in the workpiece processing sheet of the present embodiment, a protective film forming layer can also be stacked on the adhesive surface of the adhesive layer. In this case, the workpiece processing sheet of the present embodiment can be used, for example, as a protective film forming and cutting sheet. In such a sheet, by attaching the workpiece to the surface of the protective film forming layer opposite to the adhesive layer, and cutting the protective film forming layer together with the workpiece, a chip stacked with a singulated protective film forming layer can be obtained. As the workpiece, it is preferred to use a workpiece with a circuit formed on one side, in which case a protective film forming layer is usually stacked on the surface opposite to the surface with the circuit formed. By curing the singulated protective film forming layer at a specified time point, a protective film with sufficient durability can be formed on the chip. Preferably, the protective film forming layer is formed of an uncured curable adhesive.

[0064] 2. Method for manufacturing sheet for workpiece processing

[0065] The method for producing the workpiece processing sheet of the present embodiment is not particularly limited. For example, it is preferred to form an adhesive layer on a release sheet and then laminate a single surface of the base material on the surface of the adhesive layer opposite to the release sheet to obtain the workpiece processing sheet.

[0066] The formation of the above-mentioned adhesive layer can be carried out by a known method. For example, a coating liquid containing an adhesive composition for forming an adhesive layer and further containing a solvent or a dispersion medium as required is prepared. Then, the above-mentioned coating liquid is applied on the peelable surface (hereinafter, sometimes referred to as the "peeling surface") of the peeling sheet. Then, the obtained coating film is dried to form an adhesive layer.

[0067] The coating of the above-mentioned coating liquid can utilize known methods to carry out, for example, can utilize scraper bar coating method, scraper coating method (knife coating method), roller coating method, scraper coating method (blade coating method), mold coating method (diecoating method), gravure coating method etc. to carry out.In addition, as long as coating liquid can be coated, then its character is not particularly limited, there is the situation that contains the component for forming adhesive layer as solute, and there is also the situation that contains the component for forming adhesive layer as dispersion.In addition, release sheet can be peeled off as process material, and also can protect adhesive layer until it is attached to adherend.

[0068] When the adhesive composition for forming the adhesive layer contains the above-mentioned crosslinking agent, it is preferred to change the above-mentioned drying conditions (temperature, time, etc.) or to separately provide a heat treatment so that the crosslinking reaction between the polymer component in the coating and the crosslinking agent proceeds to form a crosslinked structure in the adhesive layer at a desired density. Furthermore, in order to fully proceed with the above-mentioned crosslinking reaction, after the adhesive layer is attached to the substrate, it can be aged by, for example, standing for several days at 23°C and a relative humidity of 50%.

[0069] 3. How to use the workpiece processing sheet

[0070] The workpiece processing sheet of this embodiment is suitable for use in processing workpieces such as semiconductor wafers. At this time, after the adhesive surface of the workpiece processing sheet of this embodiment is attached to the workpiece, the workpiece can be processed on the workpiece processing sheet. According to the processing, the workpiece processing sheet of this embodiment can be used as a back grinding sheet, a cutting sheet, an expansion sheet, a pick-up sheet, etc. Here, as examples of workpieces, semiconductor components such as semiconductor wafers and semiconductor packages; glass components such as glass plates can be listed.

[0071] As described above, by making the substrate of the workpiece processing sheet of the present embodiment satisfy the above-mentioned storage modulus E' and at the same time satisfy at least one of the above-mentioned Young's modulus and elongation at break, even after heating, it is possible to take into account both excellent operability and excellent expansibility. Therefore, the workpiece processing sheet of the present embodiment is particularly suitable for use in a workpiece processing method having a step of heating the workpiece processing sheet in a state where the workpiece before or after processing is stacked on the adhesive surface side.

[0072] For example, the workpiece processing sheet of the present embodiment can be suitably used in a method for manufacturing a processed workpiece having the following steps: a bonding step of bonding the workpiece to the surface of the adhesive layer of the workpiece processing sheet that is opposite to the substrate; a cutting step of cutting the workpiece on the workpiece processing sheet to obtain a processed workpiece formed by singulating the workpiece; a heating step of subjecting the heated workpiece to a heating treatment in a state bonded to the workpiece processing sheet; and a picking up step of picking up the processed workpiece from the workpiece processing sheet.

[0073] The above-mentioned laminating process, cutting process and picking process can be respectively carried out by known methods. In addition, as the above-mentioned heating process, there is no particular limitation, for example, evaporation, sputtering, baking and other treatments of the workpiece before or after processing can be listed, or heating tests for confirming reliability under high temperature environment, etc.

[0074] The conditions for the above-mentioned heating in the above-mentioned heating process can be appropriately set according to the purpose of heating. For example, as the temperature of the above-mentioned heating, it can be above 80°C, especially above 100°C, and further above 110°C. In addition, the temperature can be, for example, below 300°C, especially below 270°C, and further below 200°C. As the time of the above-mentioned heating, it can be, for example, above 10 minutes, especially above 30 minutes, and further above 120 minutes. In addition, the time can be, for example, below 25 hours, especially below 10 hours, and further below 5 hours. As a device for heating, a device corresponding to the purpose of heating can be used, for example, an oven, a heatable workbench, etc.

[0075] In addition, when the adhesive layer of the workpiece processing sheet of the present embodiment is composed of the above-mentioned active energy ray-curable adhesive, in the above-mentioned method for manufacturing a processed workpiece, it is preferred to provide an active energy ray irradiation step of irradiating the adhesive layer of the workpiece processing sheet with active energy rays and curing the adhesive layer. Thus, the adhesive layer is cured, the adhesion of the workpiece processing sheet to the processed workpiece is well reduced, and the separation of the processed workpiece becomes easy.

[0076] The above-described embodiments are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-described embodiments also includes all design changes and equivalents within the scope of protection of the present invention.

[0077] For example, another layer may be provided on the surface of the substrate opposite to the adhesive layer or between the substrate and the adhesive layer.

[0078] Example

[0079] Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[0080] [Example 1]

[0081] (1) Preparation of adhesive composition

[0082] An acrylic polymer was obtained by polymerizing 50 parts by mass of 2-ethylhexyl acrylate, 40 parts by mass of methacrylic acid, and 10 parts by mass of acrylic acid by a solution polymerization method. The weight average molecular weight (Mw) of the acrylic polymer was measured by the method described below and was 600,000.

[0083] 100 parts by mass of the acrylic polymer obtained as described above (solid content conversion, the same applies hereinafter), 40 parts by mass of a multifunctional ultraviolet curable resin (manufactured by Mitsubishi Chemical Corporation, product name "Ziguang UV-5806", Mw: 2000, 8 to 10 functionalities) as a component having an active energy ray-curable group, 4.0 parts by mass of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE HL") as a crosslinking agent, and 3.0 parts by mass of 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)benzyl]phenyl}-2-methylpropane-1-one (manufactured by BASF, product name "Omnirad 127") as a photopolymerization initiator were mixed in a solvent to obtain a coating liquid of an adhesive composition.

[0084] (2) Formation of Adhesive Layer

[0085] The coating liquid of the adhesive composition obtained in the above step (1) was applied to the release-treated surface of a release sheet (manufactured by LINTEC CORPORATION, product name "SP-PET381031") having a thickness of 38 μm and a single surface of a polyethylene terephthalate film subjected to release treatment using a silicone release agent, and the obtained coating was dried at 100° C. for 1 minute. Thus, a laminate having a 10 μm thick adhesive layer formed on the release surface of the release sheet was obtained.

[0086] (3) Production of workpiece processing sheets

[0087] One surface of a polybutylene terephthalate film (manufactured by OG CORPORATION, product name "PBT-SS80", thickness: 80 μm) as a substrate was bonded to the adhesive layer side surface of the laminate obtained in the above step (2) to obtain a workpiece processing sheet.

[0088] The weight average molecular weight (Mw) is a weight average molecular weight in terms of standard polystyrene measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).

[0089] <Measurement conditions>

[0090] ·Measurement device: HLC-8320 manufactured by TOSOH CORPORATION

[0091] ·GPC columns (passed in the following order): manufactured by TOSOH CORPORATION

[0092] TSK gel superH-H

[0093] TSK gel superHM-H

[0094] TSK gel superH2000

[0095] ·Test solvent: tetrahydrofuran

[0096] ·Measurement temperature: 40℃

[0097] [Example 2]

[0098] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a polybutylene terephthalate film (manufactured by OG CORPORATION, product name "BM-140", thickness: 140 μm) was used as the substrate.

[0099] [Example 3]

[0100] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a 100 μm-thick film obtained by film-forming pellets of a thermoplastic polyester elastomer resin (manufactured by DU PONT-TORAY Co., Ltd., product name “Hytrel 7247”) was used as the substrate.

[0101] [Example 4]

[0102] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a 100 μm-thick film obtained by film-forming pellets of a thermoplastic polyester elastomer resin (manufactured by DU PONT-TORAY Co., Ltd., product name “Hytrel 4767”) was used as the substrate.

[0103] [Comparative Example 1]

[0104] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a homopolybutylene terephthalate film (manufactured by OG CORPORATION, product name "PBT-50", thickness: 50 μm) was used as the substrate.

[0105] [Comparative Example 2]

[0106] A workpiece processing sheet was obtained in the same manner as in Example 1 except that an ethylene-methacrylic acid copolymer film (manufactured by Achilles Corporation, product name "EANU80-AL-ND", thickness: 80 μm) was used as the substrate.

[0107] [Comparative Example 3]

[0108] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a polyethylene terephthalate film having an adhesive layer on one side (manufactured by TOYOBO Co., Ltd., product name "COSMOSHINE A4100", thickness: 100 μm) was used as the substrate and an adhesive layer was laminated on the adhesive layer side of the substrate.

[0109] [Comparative Example 4]

[0110] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a polypropylene film (manufactured by DiaPlus Film Inc., product name "PL108", thickness: 80 μm) was used as the substrate.

[0111] [Test Example 1] (Measurement of Young's modulus and elongation at break of substrate)

[0112] The substrates prepared or used in Examples and Comparative Examples were cut into test pieces of 15 mm x 150 mm so that the long side (150 mm side) of the test piece was parallel to the MD direction of the substrate (the conveying direction when the substrate is manufactured).

[0113] The obtained test piece was heated in an oven at 120°C for 4 hours. Then, the test piece cooled to 23°C was subjected to a tensile test at a speed of 200 mm / min using a tensile tester (manufactured by Shimadzu Corporation, product name "AUTOGRAPH AG-IS 500N") with the distance between the clamps set to 100 mm, to measure the Young's modulus (MPa) and the elongation at break (%). These results are shown in Table 1 as the Young's modulus and elongation at break in the MD direction.

[0114] In addition, a test piece cut in a manner parallel to the CD direction (direction orthogonal to the above-mentioned MD direction) of the substrate is also prepared, and the Young's modulus (MPa) and elongation at break (%) are measured in the same manner as above for the test piece. These results are shown in Table 1 as the Young's modulus and elongation at break in the CD direction.

[0115] In addition, the average value (MPa) of the Young's modulus in the MD direction and the Young's modulus in the CD direction, and the average value (%) of the elongation at break in the MD direction and the elongation at break in the CD direction were calculated. These results are also shown in Table 1 as the average value of the Young's modulus and the average value of the elongation at break.

[0116] In addition, the substrate used in Comparative Example 2 melted due to heating at 120° C. for 4 hours and could not maintain a good sheet shape. Therefore, the Young's modulus and elongation at break of the substrate of Comparative Example 2 could not be measured.

[0117] [Test Example 2] (Measurement of Storage Modulus E' of Base Material)

[0118] The storage modulus E' (MPa) at 120°C was measured for the substrates prepared or used in Examples and Comparative Examples under the following conditions. Here, the measurement was performed in the MD direction and the CD direction of the substrate. The measurement results are shown in Table 1.

[0119] <Measurement conditions>

[0120] Measuring device: Dynamic elastic modulus measuring device, manufactured by ORIENTEC CORPORATION, product name "RHEOVIBRON DDV-II-FP"

[0121] Test start temperature: 0℃

[0122] Test end temperature: 120℃

[0123] Heating rate: 10℃ / min

[0124] Frequency: 11Hz

[0125] Furthermore, the average value (MPa) of the storage modulus E' in the MD direction and the storage modulus E' in the CD direction was calculated. The result is also shown in Table 1 as the average value of the storage modulus E'.

[0126] In addition, the substrate used in Comparative Example 2 melted due to heating at 120° C. for 4 hours and could not maintain a good sheet shape. Therefore, the storage modulus E′ of the substrate of Comparative Example 2 could not be measured.

[0127] [Test Example 3] (Evaluation of transportability)

[0128] The peeling sheet was peeled off from the workpiece processing sheet produced in the examples and comparative examples, and a dicing ring frame (manufactured by DISCO Corporation, product name "2-8-1") was attached to the peripheral edge of the surface on the exposed adhesive layer side using a multiwafer mounter (manufactured by LINTEC CORPORATION, product name "Adwill RAD-2700F / 12").

[0129] Next, the workpiece processing sheet with the ring frame attached thereto was placed on the mounting table of the multi-wafer bonding machine preheated to 120°C and in a vacuum state using a transfer arm so that the surface opposite to the attachment surface of the workpiece processing sheet was in contact with the mounting table. The workpiece processing sheet was then heated at 120°C for 4 hours on the mounting table.

[0130] Then, it was confirmed whether the workpiece processing sheet could be lifted from the mounting table and transported using the transport arm. This confirmation was performed on five sets of workpiece processing sheets in a state where the ring frame was attached.

[0131] Then, the transportability of the workpiece processing sheet was evaluated based on the following criteria.

[0132] ◎: All five groups could be transported without any problems, and the workpiece processing sheets were not welded to the mounting table.

[0133] ○: The number of groups that can be transported and the workpiece processing sheets are not welded to the mounting table is 3 or 4.

[0134] ×: The number of sets that can be transported without the workpiece processing sheet being fused to the mounting table is 2 or less.

[0135] [Test Example 4] (Evaluation of scalability)

[0136] (1) Cutting

[0137] The peeling sheet was peeled off from the workpiece processing sheet prepared in the embodiment and the comparative example, and a silicon wafer (diameter: 8 inches, thickness: 350 μm) was attached to the surface of the exposed adhesive layer side using a multi-wafer bonding machine (manufactured by LINTEC CORPORATION, product name "Adwill RAD-2700F / 12"). Then, a dicing ring frame (manufactured by DISCO Corporation, product name "2-8-1") was attached to the peripheral edge of the surface of the workpiece processing sheet on the adhesive layer side (a position not overlapping with the silicon wafer).

[0138] Next, the silicon wafer was cut on the workpiece processing sheet under the following conditions.

[0139] <Cutting conditions>

[0140] Cutting device: manufactured by DISCO Corporation, product name "DFD-6362"

[0141] Blade: Made by DISCO Corporation, product name "NBC-ZH2050-27HECC"

[0142] Blade speed: 30000rpm

[0143] Cutting speed: 50mm / min

[0144] · Cutting depth: up to a depth of 20 μm in the substrate

[0145] Cutting size: 3mm×3mm

[0146] (2) Heating

[0147] Next, the workpiece processing sheet was heated in an oven at 120° C. for 4 hours in a state where the obtained chips and the ring frame were stacked.

[0148] (3) Extension

[0149] Next, the workpiece processing sheet was expanded using an expansion device (Mitsubishi Electric Corporation., product name "MELSEC-G0T F930G0T"). At this time, the expansion was performed by pulling down the annular frame by 10 mm at a speed of 3 mm / s. Then, the expandability of the workpiece processing sheet was evaluated based on the following benchmarks. The results are shown in Table 1.

[0150] ◯: The sheet can be expanded well, and there is no breakage of the workpiece processing sheet or peeling of the workpiece processing sheet from the ring frame.

[0151] ×: The workpiece processing sheet was broken or peeled off from the ring frame, and expansion could not be performed.

[0152] In addition, in the workpiece processing sheet of Comparative Example 2, the base material melted during heating in the above step (2), and the sheet shape could not be well maintained, resulting in failure to perform the expansion process. Therefore, the expandability of Comparative Example 2 was evaluated as "×".

[0153] [Table 1]

[0154]

[0155] As can be seen from Table 1, the workpiece processing sheet produced in Examples has excellent transportability (handling properties) even after being heated at 120° C. for 4 hours, and also has excellent expandability.

[0156] Industrial Applicability

[0157] The workpiece processing sheet of the present invention can be suitably used for processing a workpiece such as a semiconductor wafer.

Claims

1. A workpiece processing sheet comprising a base material and an adhesive layer laminated on one side of the base material, wherein: The substrate is made of at least one of polybutylene terephthalate and thermoplastic polyester elastomer. The Young's modulus of the substrate at 23° C. after heating at 120° C. for 4 hours is 400 MPa or more and 600 MPa or less, The storage modulus E' of the substrate at 120° C. is 100 MPa to 200 MPa.

2. A workpiece processing sheet comprising a base material and an adhesive layer laminated on one side of the base material, wherein: The substrate is made of at least one of polybutylene terephthalate and thermoplastic polyester elastomer. The elongation at break of the substrate at 23°C after heating at 120°C for 4 hours is 200% or more and 750% or less, The storage modulus E' of the substrate at 120° C. is 100 MPa to 200 MPa.

3. The workpiece processing sheet according to claim 1 or 2, characterized in that: At the same time: The Young's modulus of the substrate at 23°C after heating at 120°C for 4 hours is 400 MPa or more and 600 MPa or less, and The elongation at break of the substrate at 23° C. after heating at 120° C. for 4 hours is 200% or more and 750% or less.

4. The workpiece processing sheet according to claim 1 or 2, characterized in that: The thickness of the substrate is 50 μm or more and 200 μm or less.

5. The workpiece processing sheet according to claim 1 or 2, characterized in that: The adhesive layer is formed of an active energy ray-curable adhesive.

6. The workpiece processing sheet according to claim 1 or 2, characterized in that: The workpiece processing sheet is used in a workpiece processing method including a heating step in a state where the workpiece before or after processing is stacked on the surface of the adhesive layer opposite to the substrate.

7. A method for manufacturing a processed workpiece, characterized in that: It has: A step of laminating a workpiece to a surface of the adhesive layer of the workpiece processing sheet according to claim 1 or 2 that is opposite to the substrate; A cutting step of obtaining processed workpieces obtained by singulating the workpieces by cutting the workpieces on the workpiece processing sheet; subjecting the processed workpiece to a heating step accompanied by heating treatment in a state where the workpiece is bonded to the workpiece processing sheet; and A picking up step of picking up the processed workpiece from the workpiece processing sheet.

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