Workpiece processing sheet and method for manufacturing semiconductor device

Abstract

Provided is a workpiece processing sheet comprising: a release sheet having a release agent layer on one surface side of glassine paper; and a work attachment layer laminated on a surface of the release agent layer on the opposite side to the glassine paper. The workpiece processing sheet can greatly contribute to reducing carbon dioxide emissions and decreasing the use of plastic materials.

Description

Workpiece processing sheet and semiconductor device manufacturing method

[0001] The present invention relates to a workpiece processing sheet provided with a release sheet and a method for manufacturing a semiconductor device using the workpiece processing sheet.

[0002] Semiconductor wafers, such as silicon and gallium arsenide, and various packages are manufactured in large diameters, cut and separated (diced) into small element pieces (semiconductor chips), and then individually peeled (picked up) before being transferred to the next process, the mounting process. During this process, the semiconductor wafers and other workpieces are attached to a workpiece processing sheet and undergo processing such as backgrinding, dicing, cleaning, drying, expanding, picking up, and mounting.

[0003] The above-mentioned workpiece processing sheet generally comprises a base material and a workpiece attachment layer laminated on one side of the base material. The workpiece attachment layer may be a pressure-sensitive adhesive layer, an adhesive layer, a protective film-forming layer, or the like, depending on the intended use of the workpiece processing sheet.

[0004] A release sheet is usually laminated on the workpiece attachment layer side of a workpiece processing sheet in order to protect the side until the side is attached to the workpiece. For example, Patent Document 1 discloses a pressure-sensitive adhesive sheet in which a release sheet is laminated on the side of the pressure-sensitive adhesive layer in a laminate of a substrate and a pressure-sensitive adhesive layer.

[0005] A release sheet generally comprises a release substrate and a release agent layer formed on one side thereof. Resin films have been widely used as the release substrate. For example, Patent Document 1 discloses a release sheet manufactured using a polyester film as the release substrate.

[0006] JP 2010-168541 A

[0007] In recent years, the Sustainable Development Goals (SDGs) have been established, calling for the reduction of carbon dioxide emissions and the use of plastic materials. Improvements from the perspective of the SDGs are also required in the technical fields related to workpiece processing sheets and release sheets.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a work processing sheet that can greatly contribute to reducing carbon dioxide emissions and the use of plastic materials.

[0009] In order to achieve the above object, first, the present invention provides a workpiece processing sheet comprising a release sheet having a release agent layer on one side of glassine paper, and a workpiece attachment layer laminated on the side of the release agent layer opposite the glassine paper (Invention 1).

[0010] The workpiece processing sheet according to the above invention (Invention 1) uses glassine paper as the release substrate of the release sheet, thereby reducing carbon dioxide emissions and the amount of plastic material used while still ensuring sufficient functionality as a release sheet.

[0011] In the above invention (Invention 1), the release sheet preferably includes a polyethylene laminate layer laminated between the glassine paper and the release agent layer (Invention 2).

[0012] In the above inventions (Inventions 1 and 2), the arithmetic mean height Ra of the surface of the release sheet facing the release agent layer is preferably 0.01 μm or more and 2.0 μm or less (Invention 3).

[0013] In the above inventions (Inventions 1 to 3), in a clean environment, the release sheet is peeled off from the workpiece processing sheet, and the exposed surface of the workpiece attachment layer is attached to the mirror surface of a silicon wafer. After storing for 24 hours, it is preferable that the number of particles with a particle size of 0.270 μm or less adhering to the mirror surface exposed by peeling off the workpiece attachment layer is 500 or less (Invention 4).

[0014] In the above inventions (Inventions 1 to 4), the work attachment layer is preferably at least one of a pressure-sensitive adhesive layer, an adhesive layer, and a protective film-forming layer (Invention 5).

[0015] In the above inventions (Inventions 1 to 5), the workpiece processing sheet is preferably at least one of a dicing sheet, a back grinding sheet, an expanding sheet, a die bonding sheet, a back surface protection sheet, and a bump surface protection sheet (Invention 6).

[0016] Secondly, the present invention provides a method for manufacturing a semiconductor device, characterized by comprising the steps of peeling the release sheet from the workpiece processing sheet (Inventions 1 to 6) to attach one or more workpieces to the exposed surface of the workpiece attachment layer, and separating at least one of the workpieces from the workpiece attachment layer and placing it on a predetermined object (Invention 7).

[0017] The workpiece processing sheet according to the present invention can greatly contribute to reducing carbon dioxide emissions and the use of plastic materials.

[0018] The following describes an embodiment of the present invention. The workpiece processing sheet according to this embodiment includes a release sheet having a release agent layer on one side of glassine paper, and a workpiece attachment layer laminated on the side of the release agent layer opposite the glassine paper.

[0019] The release sheet in this embodiment uses glassine paper as the release substrate, and therefore can fully exhibit the same functions as general release sheets that use resin release substrates. In particular, glassine paper generates much less dust and dirt than regular paper, which can prevent the workpiece processing sheet, the workpiece, and even the equipment that handles the workpiece processing sheet from being contaminated by dust and dirt.

[0020] Furthermore, the work processing sheet according to this embodiment uses glassine paper as the release base material, which significantly reduces carbon dioxide emissions when the release sheet is discarded and also reduces the amount of plastic material used. In particular, glassine paper generates less carbon dioxide when burned than general resin films. Furthermore, glassine paper is essentially made from biomass, and the amount of carbon dioxide absorbed by the plants used as raw materials can be offset by the amount of carbon dioxide generated during combustion. As a result, the actual carbon dioxide emissions from glassine paper are significantly lower than those from general resin films.

[0021] As described above, by using the workpiece processing sheet of this embodiment as a replacement for conventional workpiece processing sheets that use a resin film as a release substrate, it is possible to make a significant contribution to reducing carbon dioxide emissions and the use of plastic materials without compromising the function of the workpiece processing sheet.

[0022] While the use of paper as a release substrate for release sheets has been considered in the past, the glassine paper used in the workpiece processing sheet according to this embodiment has various advantages over plain paper, including its low dust and dirt generation, as mentioned above, and its high smoothness. This makes it easier to improve the smoothness of the release sheet itself, which in turn improves the surface smoothness of the workpiece attachment layer attached to the release sheet. As a result, the use of the workpiece processing sheet according to this embodiment enables highly accurate workpiece processing.

[0023] Furthermore, glassine paper has higher strength than plain paper, which allows for the production of longer workpiece processing sheets, making it easier to reduce production costs. Glassine paper also has better water and oil resistance than plain paper, making it less susceptible to external environmental factors such as humidity, making it easier to stabilize quality. Furthermore, glassine paper has higher transparency than plain paper, which means it can be easily recognized by sensors in devices that handle glassine paper and workpiece processing sheets.

[0024] 1. Release Sheet As described above, the release sheet in this embodiment comprises a release agent layer on one side of the glassine paper. It is also preferable that the release sheet in this embodiment further comprises a polyethylene laminate layer laminated between the glassine paper and the release agent layer. By providing the polyethylene laminate layer, the smoothness of the surface of the release sheet facing the release agent layer (hereinafter sometimes referred to as the "release surface") can be further improved.

[0025] (1) Glassine Paper The glassine paper used in this embodiment is not particularly limited, and known materials can be used. Known pulps can be used to form the glassine paper, and examples of pulp that can be used include wood pulps such as softwood kraft pulp (N wood), hardwood kraft pulp (L wood), softwood sulfite pulp, hardwood sulfite pulp, dissolving pulp, and mercerized pulp, and non-wood pulps such as flax pulp, Manila hemp pulp, and kenaf pulp. Among these, it is preferable to use at least one of softwood kraft pulp and hardwood kraft pulp, and it is particularly preferable to use a combination of softwood kraft pulp and hardwood kraft pulp.

[0026] When softwood kraft pulp and hardwood kraft pulp are used in combination, the ratio of softwood kraft pulp to hardwood kraft pulp is preferably 5:95 to 50:50, and more preferably 15:85 to 40:60.

[0027] Furthermore, in the glassine paper of this embodiment, various additives may be added to the pulp, and examples thereof include fillers, wet strength agents, dry strength agents, sizing agents, aluminum sulfate, various anionic, cationic, nonionic and amphoteric retention aids, drainage aids, color dyes, color pigments, fluorescent whitening agents, pH adjusters, antifoaming agents, pitch control agents, slime control agents, and the like.

[0028] The method for beating the pulp described above is not particularly limited, and the pulp can be beaten using a known refiner, etc. The beaten pulp is then subjected to high-pressure processing using a smooth roller such as a supercalender, thereby obtaining the glassine paper of the present embodiment.

[0029] The basis weight of the glassine paper in this embodiment is 30 g / m ２ It is preferable that the content is 40 g / m or more, and particularly 40 g / m ２ It is preferable that the density is 45 g / m or more, and more preferably 45 g / m ２ The basis weight is preferably 150 g / m or more. ２ It is preferable that the weight is 120 g / m or less, and particularly 120 g / m ２ It is preferable that the density is 100 g / m or less, and more preferably 100 g / m ２ When the basis weight of the glassine paper is within the above range, the release sheet has sufficient strength and excellent handleability.

[0030] In this embodiment, the thickness of the glassine paper is preferably 20 μm or more, particularly preferably 25 μm or more, and even more preferably 30 μm or more. Furthermore, the thickness is preferably 200 μm or less, particularly preferably 180 μm or less, and even more preferably 160 μm or less. By having the thickness of the glassine paper within the above range, the release sheet has sufficient strength and excellent handleability.

[0031] (2) Polyethylene Laminate Layer As the polyethylene laminate layer in this embodiment, a polyethylene laminate layer generally used for laminating on glassine paper can be used. That is, the polyethylene laminate layer in this embodiment is preferably formed by laminating polyethylene melted by heating onto one side of the glassine paper by applying pressure using a smooth roll.

[0032] As the polyethylene, low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), etc. can be used appropriately depending on the purpose.

[0033] When melting the polyethylene, it is preferably heated to 95 to 160° C., particularly 1000 to 140° C. Furthermore, it is preferable to use an ultra-high smoothness roll as the smooth roll.

[0034] In this embodiment, the thickness of the polyethylene laminate layer is preferably 5 μm or more, particularly preferably 8 μm or more, and even more preferably 10 μm or more. Furthermore, the thickness is preferably 40 μm or less, particularly preferably 30 μm or less. Having the thickness of the polyethylene laminate layer within this range provides the release sheet with superior smoothness on its release surface.

[0035] (3) Release Agent Layer The release agent constituting the release agent layer in this embodiment is not particularly limited, and any release agent commonly used in release sheets can be used. As the release agent, silicone-based release agents, fluorine-based release agents, long-chain alkyl release agents, rubber-based release agents, etc. can be used as appropriate, and among these, silicone-based release agents are preferred because they are inexpensive and provide stable performance.

[0036] The release agent layer in this embodiment can be formed by a general method. For example, when forming the release agent layer using a silicone-based release agent, a release agent composition that is a material for the silicone-based release agent is applied to one side of glassine paper (when a polyethylene laminate layer is provided, the side on the polyethylene laminate layer side), and the resulting coating film is cured by a treatment such as heating, thereby forming the release agent layer.

[0037] The basis weight of the release agent layer in this embodiment is 0.1 g / m ２ It is preferable that the content is 0.3 g / m or more, and particularly 0.3 g / m ２ The basis weight is preferably 1.5 g / m or more. ２ It is preferable that the content is 1.0 g / m or less, and particularly 1.0 g / m ２ When the basis weight of the release agent layer is within the above range, it becomes easy to form a release agent layer that exhibits good releasability.

[0038] In this embodiment, the thickness of the release agent layer is preferably 50 nm or more, particularly preferably 100 nm or more, and even more preferably 20 nm or more. The thickness is also preferably 1000 nm or less, particularly preferably 80 nm or less, and even more preferably 70 nm or less. By ensuring that the thickness of the release agent layer is within the above range, it becomes easier to form a release agent layer that exhibits good releasability.

[0039] (4) Surface Roughness The release sheet of this embodiment preferably exhibits the following surface roughness on its release surface. That is, the arithmetic mean height Ra of the release surface is preferably 2.0 μm or less, particularly preferably 1.5 μm or less, and even more preferably 1.4 μm or less. When the arithmetic mean height Sa of the release surface is within the above range, the release surface has superior smoothness, and the workpiece attachment layer laminated on the release surface has even superior smoothness. As a result, the workpiece processing sheet of this embodiment facilitates high-precision workpiece processing. The lower limit of the arithmetic mean height Ra is not particularly limited and may be, for example, 0.01 μm or more, particularly 0.05 μm or more, or even 0.1 μm or more. Details of the method for measuring the arithmetic mean height Ra are as described in the test examples below.

[0040] 2. Workpiece Adhesion Layer In this embodiment, the workpiece attachment layer is not particularly limited as long as it is a layer to which a workpiece can be attached. Specifically, the workpiece attachment layer is preferably at least one of a pressure-sensitive adhesive layer, an adhesive layer, and a protective film-forming layer. These layers can be selected appropriately depending on the application of the workpiece processing sheet.

[0041] Here, the workpiece processing sheet according to this embodiment is preferably used as at least one of a dicing sheet, a back-grinding sheet, an expanding sheet, a die-bonding sheet, a back surface protection sheet, and a bump surface protection sheet. When the workpiece processing sheet is a dicing sheet, a back-grinding sheet, or an expanding sheet, the workpiece attachment layer is preferably an adhesive layer. When the workpiece processing sheet is a die-bonding sheet, the workpiece attachment layer is preferably an adhesive layer. Furthermore, when the workpiece processing sheet is a back surface protection sheet or a bump surface protection sheet, the workpiece attachment layer is preferably a protective film-forming layer.

[0042] (1) Pressure-sensitive adhesive layer As the pressure-sensitive adhesive layer, a pressure-sensitive adhesive layer commonly used for forming a dicing sheet, a back-grinding sheet, an expanding sheet, etc. can be used. As a pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, for example, an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a polyester pressure-sensitive adhesive, a polyvinyl ether pressure-sensitive adhesive, etc. Among these, it is preferable to use an acrylic pressure-sensitive adhesive, from the viewpoint of easily exerting the desired adhesive strength.

[0043] Furthermore, the adhesive constituting the adhesive layer may not be active energy ray curable, but is preferably active energy ray curable. By using an active energy ray curable adhesive, the adhesive layer can be cured by irradiation with active energy rays, and the workpiece can be easily separated from the adhesive layer.

[0044] The active energy ray-curable adhesive may be one containing an active energy ray-curable polymer as a main component, or one containing a mixture of an active energy ray-non-curable polymer (a polymer not curable with active energy ray) and a monomer and / or oligomer having at least one active energy ray-curable group as a main component. In addition, the active energy ray-curable adhesive may be a mixture of an active energy ray-curable polymer and a monomer and / or oligomer having at least one active energy ray-curable group.

[0045] The active energy ray-curable polymer is preferably a (meth)acrylic acid ester polymer (hereinafter sometimes referred to as an "active energy ray-curable polymer") having an active energy ray-curable functional group (active energy ray-curable group) introduced into its side chain. This 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 having a functional group bonded to the functional group. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the term "polymer" also includes the concept of "copolymer."

[0046] The acrylic polymer having the functional group-containing monomer unit may be obtained by polymerizing the functional group-containing monomer and other monomers. As such functional group-containing monomers and other monomers, and the unsaturated group-containing compounds, known compounds can be used, for example, those disclosed in WO 2018 / 084021.

[0047] The weight-average molecular weight of the active-energy radiation-curable polymer is preferably 10,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more. The weight-average molecular weight is preferably 1,500,000 or less, particularly preferably 1,000,000 or less. The weight-average molecular weight (Mw) in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0048] As the above-mentioned active energy ray non-curable polymer, for example, the above-mentioned (meth)acrylic acid ester polymer before being reacted with the unsaturated group-containing compound can be used.

[0049] The weight-average molecular weight of the (meth)acrylic acid ester polymer as the non-active energy ray-curable polymer is preferably 10,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 1,500,000 or less, particularly preferably 1,000,000 or less.

[0050] Furthermore, as the above-mentioned monomer and / or oligomer having at least one active energy ray-curable group, for example, an ester of a polyhydric alcohol and (meth)acrylic acid can be used.

[0051] It is also preferable to add a crosslinking agent to the active energy ray-curable adhesive. The use of a crosslinking agent makes it easier for the active energy ray-curable adhesive to have the desired cohesive strength. As the crosslinking agent, a polyfunctional compound reactive with the functional groups of the active energy ray-curable adhesive or the like can be used. Examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, and reactive phenolic resins. The amount of crosslinking agent is not particularly limited and may be appropriately determined within the range of 1 to 15 parts by mass per 100 parts by mass of the active energy ray-curable adhesive, for example.

[0052] Furthermore, when ultraviolet rays are used as the active energy rays for curing the active energy ray-curable adhesive, it is preferable to add a photopolymerization initiator to the adhesive. By using the photopolymerization initiator, it is possible to effectively reduce the polymerization and curing time of the adhesive and the amount of light irradiation, particularly when ultraviolet rays are used as the active energy rays.

[0053] In the present embodiment, when the work attachment layer is an adhesive layer, the thickness of the adhesive layer is preferably 3 to 50 μm, more preferably 5 to 40 μm, and even more preferably 10 to 20 μm. By having the thickness of the adhesive layer within the above range, the work attachment layer can easily exhibit the desired adhesive strength.

[0054] (2) Adhesive Layer When the work attachment layer in this embodiment is an adhesive layer, as described above, the workpiece processing sheet according to this embodiment is usually used as a die-bonding sheet. Therefore, there are no particular restrictions on the material constituting the adhesive layer, as long as it can form an adhesive layer on the workpiece.

[0055] Materials for forming such adhesive layers include those composed of a thermoplastic resin and a low-molecular-weight thermosetting adhesive component, and those composed of a B-stage (semi-cured) thermosetting adhesive component. Among these, materials for forming the adhesive layer are preferably those containing a thermoplastic resin and a thermosetting adhesive component. Examples of thermoplastic resins include (meth)acrylic copolymers, polyester resins, urethane resins, phenoxy resins, polybutene, polybutadiene, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, ethylene (meth)acrylic acid copolymers, ethylene (meth)acrylic acid ester copolymers, polystyrene, polycarbonate, and polyimide. Among these, (meth)acrylic copolymers are preferred in terms of adhesion and film-forming properties (sheet processability). Examples of the thermosetting adhesive component include epoxy resins, polyimide resins, phenol resins, silicone resins, cyanate resins, bismaleimide triazine resins, allylated polyphenylene ether resins (thermosetting PPE), formaldehyde resins, unsaturated polyesters, and copolymers thereof. Among these, epoxy resins are preferred from the viewpoint of adhesiveness.

[0056] When the work attachment layer in this embodiment is an adhesive layer, the thickness of the adhesive layer can be selected appropriately depending on the purpose, and is, for example, preferably 1 to 50 μm, particularly preferably 3 to 25 μm, and even more preferably 5 to 20 μm.

[0057] (3) Protective Film Forming Layer When the workpiece attachment layer in this embodiment is a protective film forming layer, the protective film forming layer is preferably made of an uncured curable adhesive. In this case, after a workpiece such as a semiconductor wafer or semiconductor chip is placed on the protective film forming layer, the protective film can be firmly adhered to the workpiece by curing the protective film forming layer. As a result, a protective film with excellent durability can be formed on the workpiece.

[0058] The protective film forming layer preferably has adhesiveness at room temperature or exhibits adhesiveness upon heating. This allows the workpiece to be laminated to the protective film forming layer when superimposed thereon as described above. The curable adhesive constituting the protective film forming layer having such properties preferably contains a curable component and a binder polymer component. The curable component can be a thermosetting component, an energy ray curable component, or a mixture thereof. From the viewpoint of the curing method of the protective film forming layer and the heat resistance after curing, it is particularly preferable to use a thermosetting component, and from the viewpoint of the curing time, it is preferable to use an energy ray curable component.

[0059] When the workpiece attachment layer in this embodiment is a protective film-forming layer, the thickness of the protective film-forming layer can be selected appropriately depending on the purpose, and is preferably, for example, 3 to 50 μm, particularly preferably 5 to 45 μm, and even more preferably 10 to 25 μm. Furthermore, when the object to be attached is the surface of a workpiece having bumps on its surface, the thickness of the protective film-forming layer is preferably 5 to 50 μm, particularly preferably 10 to 30 μm, and even more preferably 15 to 25 μm. Furthermore, when used in a process in which the protective film-forming layer is filled into grooves in a workpiece having grooves on its surface, the thickness of the protective film-forming layer is preferably 20 to 75 μm, particularly preferably 30 to 60 μm, and even more preferably 40 to 55 μm.

[0060] (4) Layer Configuration The workpiece processing sheet according to this embodiment may include other members as appropriate depending on the intended use of the workpiece processing sheet and the specific type of workpiece attachment layer.

[0061] For example, when the workpiece processing sheet is used as a dicing sheet, back-grinding sheet, or expanding sheet and the workpiece attachment layer is an adhesive layer, it is preferable that a substrate be laminated on the surface of the workpiece attachment layer (adhesive layer) opposite the release sheet. By providing a substrate, when the release sheet is peeled off from the workpiece processing sheet, the workpiece attachment layer is supported by the substrate, making it easier to process the workpiece on the workpiece attachment layer.

[0062] Furthermore, even when the workpiece processing sheet is used as a die-bond sheet and the workpiece attachment layer is an adhesive layer, it is preferable that a substrate be laminated on the surface of the workpiece attachment layer (adhesive layer) opposite to the release sheet. By providing a substrate, the workpiece attachment layer is supported by the substrate, making it easier to laminate the adhesive layer on the workpiece.

[0063] Furthermore, when the workpiece processing sheet is a backside protective sheet and the workpiece attachment layer is a protective film-forming layer, in a first embodiment, it is preferable that an adhesive layer is laminated on the surface of the workpiece attachment layer (protective film-forming layer) opposite the release sheet, and a substrate is further laminated on the surface of the adhesive layer opposite the workpiece attachment layer. This configuration, in which the workpiece attachment layer, adhesive layer, and substrate are laminated in this order on the release sheet, makes it easy to transfer the workpiece attachment layer (protective film-forming layer) to the target workpiece. In a second embodiment, it is also preferable that another release sheet is laminated on the surface of the workpiece attachment layer (protective film-forming layer) opposite the release sheet. Such a workpiece processing sheet allows the protective film-forming layer to be transferred to the workpiece without a substrate.

[0064] When the workpiece processing sheet is a bump protection sheet and the workpiece attachment layer is a protective film-forming layer, it is preferable that an intermediate release agent layer be laminated on the surface of the workpiece attachment layer (protective film-forming layer) opposite the release sheet, and that a buffer layer be laminated on the surface of the intermediate release agent layer opposite the workpiece attachment layer, and that a substrate be laminated on the surface of the buffer layer opposite the intermediate release layer. This configuration makes it easy to transfer the workpiece attachment layer (protective film-forming layer) to the target bump-bearing workpiece.

[0065] As the substrate, a known material may be used depending on the purpose, and it is preferable to use, for example, a resin film.

[0066] (5) Surface Roughness In the workpiece processing sheet according to this embodiment, the exposed surface of the workpiece attachment layer exposed by peeling off the release sheet preferably exhibits the following surface roughness. That is, the arithmetic mean height Sa of the exposed surface is preferably 1.5 μm or less, particularly preferably 1.2 μm or less, and even more preferably 0.9 μm or less. By having the arithmetic mean height Sa of the exposed surface within the above range, the exposed surface exhibits superior smoothness, making it easier to perform high-precision workpiece processing. The lower limit of the arithmetic mean height Sa is not particularly limited and may be, for example, 0.1 μm or more, particularly 0.15 μm or more, or even 0.2 μm or more. Details of the method for measuring the arithmetic mean height Sa are as described in the test examples below.

[0067] 3. Physical Properties of the Workpiece Processing Sheet In the workpiece processing sheet according to this embodiment, the release sheet is peeled off in a clean environment, and the exposed surface of the workpiece attachment layer is attached to the mirror surface of a silicon wafer. After storing for 24 hours, the number of particles with a particle size of 0.270 μm or less adhering to the mirror surface exposed by peeling off the workpiece attachment layer is preferably 500 or less, more preferably 100 or less, and even more preferably 50 or less.

[0068] In the work processing sheet according to this embodiment, by using glassine paper as the release substrate, the generation of dust and dirt can be suppressed compared to when ordinary paper or the like is used, and as a result, it is easier to achieve the above-mentioned particle number.

[0069] The lower limit of the number of particles is not particularly limited, and may be, for example, 5 or more, particularly 10 or more. Details of the method for measuring the number of particles are as described in the test examples below.

[0070] 4. Manufacturing Method of Workpiece Processing Sheet The manufacturing method of the workpiece processing sheet according to this embodiment is not particularly limited. For example, a workpiece attachment layer can be formed on the release surface of the release sheet manufactured as described above, and then, if necessary, a substrate or the like can be laminated on the surface of the workpiece attachment layer opposite the release sheet to obtain the desired workpiece processing sheet.

[0071] The formation of a work attachment layer on the release surface of the release sheet can be carried out by a known method. For example, when forming a pressure-sensitive adhesive layer as a work attachment layer, a coating liquid containing a pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer and, if desired, a solvent or dispersion medium is prepared, and the coating liquid is applied to the release surface of the release sheet using a die coater, curtain coater, spray coater, slit coater, knife coater, roll knife coater, applicator, etc. to form a coating film, and the coating film is dried to form a pressure-sensitive adhesive layer. The properties of the coating liquid are not particularly limited as long as it can be applied, and it may contain the components for forming the pressure-sensitive adhesive layer as a solute or as a dispersoid.

[0072] When the coating liquid for forming the adhesive layer contains a crosslinking agent, the crosslinking reaction between the active energy radiation-curable polymer and the crosslinking agent in the coating film can be advanced by changing the drying conditions (temperature, time, etc.) or by separately providing a heat treatment, thereby forming a crosslinked structure at a desired density in the adhesive layer. In order to sufficiently advance this crosslinking reaction, after laminating the adhesive layer on the substrate by the above-mentioned method, the obtained work processing sheet can be cured by, for example, leaving it to stand in an environment of 23°C and a relative humidity of 50% for several days.

[0073] 5. Method of Using the Workpiece Processing Sheet The workpiece processing sheet according to this embodiment can be used for processing a workpiece. That is, the release sheet is peeled off from the workpiece processing sheet according to this embodiment, the exposed surface of the workpiece attachment layer is attached to one side of the workpiece, and then the workpiece can be processed on the workpiece processing sheet.

[0074] Examples of the above processing include dicing, back grinding, expanding, picking up, die bonding, back surface protection, bump surface protection, and the like.

[0075] The workpiece to be processed using the workpiece processing sheet according to this embodiment is not particularly limited, and examples thereof include semiconductor components such as semiconductor wafers and semiconductor packages, and glass components such as glass plates.

[0076] When the workpiece is a semiconductor material, the workpiece processing sheet according to this embodiment can also be used in a method for manufacturing a semiconductor device. This method includes, for example, a step of peeling the release sheet from the workpiece processing sheet according to this embodiment to expose the workpiece attachment layer, attaching one or more workpieces to the exposed surface of the workpiece attachment layer, and a step of separating at least one of the workpieces from the workpiece attachment layer and placing it on a predetermined object. The above-mentioned attachment and separation can be performed using known methods.

[0077] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0078] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0079] [Example 1] (1) Preparation of Release Sheet A pulp slurry was obtained by beating 30 parts by mass of softwood kraft pulp (N wood) and 70 parts by mass of hardwood kraft pulp (L wood) to prepare a release sheet having a basis weight of 62 g / m. ２ of glassine paper was obtained.

[0080] Molten polyethylene was laminated onto one side of the glassine paper using a two-roll press coater with an ultra-smooth (ultra-mirror) roll surface, resulting in a laminate in which a polyethylene laminate layer with a thickness of 19 μm was formed on one side of the glassine paper.

[0081] Furthermore, a silicone-based release agent (manufactured by Shin-Etsu Silicone Co., Ltd., product name "KNS-320A") was applied as a release agent composition to the surface of the polyethylene laminate layer side of the laminate in an amount of 0.50 g / m using a bar coater. ２ The resulting coating film was heated at 100°C for 30 seconds. This caused the coating film to harden and become a release agent layer. As a result, a release sheet was obtained in which the release agent layer, polyethylene laminate layer, and glassine paper were laminated in this order.

[0082] (2) Preparation of Workpiece Processing Sheet 70 parts by mass of n-butyl acrylate, 15 parts by mass of methyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate were polymerized by solution polymerization to obtain a (meth)acrylic acid ester polymer. Subsequently, 2-methacryloyloxyethyl isocyanate (MOI) was reacted in an amount equivalent to 80 mol % of the 2-hydroxyethyl acrylate constituting the (meth)acrylic acid ester polymer to obtain a (meth)acrylic acid ester polymer (active energy radiation curable polymer) having active energy radiation curable groups introduced into its side chains. The weight average molecular weight of this active energy radiation curable polymer was measured using the method described below and found to be 600,000.

[0083] 100 parts by mass (solid content equivalent, the same applies hereinafter) of the active-energy radiation-curable polymer obtained above, 0.6 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem Co., Ltd., product name "BHS8515") as a crosslinking agent, and 3 parts by mass of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals Co., Ltd., product name "Irgacure 184") were mixed in a solvent to obtain a coating liquid of a pressure-sensitive adhesive composition having a solid content concentration of 20%.

[0084] The coating solution of the pressure-sensitive adhesive composition obtained as described above was applied to the release surface of the release sheet prepared in the above step (1), and the resulting coating film was dried by heating to obtain a laminate comprising a pressure-sensitive adhesive layer having a thickness of 5 μm formed by the dried coating film and the release sheet laminated together.

[0085] One side of an ethylene-methyl methacrylate (EMMA) sheet (thickness: 80 μm) serving as a substrate was bonded to the adhesive layer side of the laminate, thereby obtaining a workpiece processing sheet in which the release surface of the release sheet prepared in the above step (1) was laminated to the adhesive surface of the adhesive sheet consisting of the substrate and the adhesive layer.

[0086] (3) Measurement of Weight-Average Molecular Weight The weight-average molecular weight (Mw) is a weight-average molecular weight converted into standard polystyrene, measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement Conditions> Measurement device: HLC-8320, manufactured by Tosoh Corporation GPC columns (passed in the following order): TSK gel super H-H, TSK gel super HM-H, TSK gel super H2000, manufactured by Tosoh Corporation Measurement solvent: tetrahydrofuran Measurement temperature: 40°C

[0087] [Example 2] A workpiece processing sheet was obtained in the same manner as in Example 1, except that a 16 μm thick polyethylene laminate layer was formed on the release sheet using a two-roll size press coater with a smooth (semi-mirror) roll surface.

[0088] Example 3 A workpiece processing sheet was obtained in the same manner as in Example 1, except that the polyethylene laminate layer of the release sheet was not formed.

[0089] Comparative Example 1 A workpiece processing sheet was obtained in the same manner as in Example 1, except that a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031") was used, in which a silicone-based release agent layer was formed on one side of a 38 μm-thick polyethylene terephthalate (PET) film.

[0090] [Comparative Example 2] Instead of glassine paper, a paper with a basis weight of 60 g / m ２ A workpiece processing sheet was obtained in the same manner as in Example 1, except that plain paper of 15 μm thick was used and a 2-roll size press coater with a smooth (semi-mirror) roll surface was used to form a polyethylene laminate layer of 15 μm thick.

[0091] [Test Example 1] (Calculation of carbon dioxide emissions) For the release sheets produced in the Examples and Comparative Examples, the density of the glassine paper, polyethylene laminate layer, PET film, and plain paper used in each was used to calculate the carbon dioxide emissions per 1 m of these components. ２The weight per unit mass was calculated. Based on the combustion reaction formulas of these components, the amount of carbon dioxide emitted when these components are burned was calculated. The amount of carbon dioxide emitted per unit mass was calculated using the coefficients listed in the greenhouse gas emission coefficients published by the Ministry of the Environment. ２ The carbon dioxide emissions generated when each release sheet is discarded were determined for each component. Furthermore, the carbon dioxide emissions of the release sheet (g-CO ２ｅ / m ２ The results are shown in Table 1.

[0092] Although the release sheet has a release agent layer, the mass of the release agent layer is much smaller than that of the other components, and the amount of carbon dioxide emitted from the release agent layer is much smaller than that of the other components, so the amount of carbon dioxide emitted from the release agent layer was not taken into consideration.

[0093] [Test Example 2] (Measurement of adhesive strength) The workpiece processing sheets manufactured in the examples and comparative examples were left to stand for one week in an environment of 23°C temperature and 50% humidity, and then cut into a size of 25 mm width and 300 mm length to prepare test samples.

[0094] The release sheet was peeled off from the test sample, and the exposed surface of the pressure-sensitive adhesive layer was placed on the mirror surface of a 6-inch silicon wafer, and the wafer was laminated by applying a load by moving a 2 kg roller back and forth once, and left for 20 minutes. This was used as a laminate for adhesive strength measurement.

[0095] For the obtained laminate for adhesive strength measurement, the workpiece processing sheet (adhesive sheet consisting of a substrate and an adhesive layer) was peeled from the silicon wafer at a peeling speed of 300 mm / min and a peeling angle of 180° using the 180° peel method in accordance with JIS Z0237: 2009, and the adhesive strength (mN / 25 mm) was measured. The results are shown in Table 1 as adhesive strength before UV irradiation.

[0096] In addition, the laminate for adhesive strength measurement obtained in the same manner as above was irradiated with ultraviolet (UV) light (illuminance: 230 mW / cm) under nitrogen using an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2010") on the substrate side of the work processing sheet.２ , Light amount: 180mJ / cm ２ ) was performed to cure the adhesive layer. Thereafter, the adhesive strength (mN / 25 mm) was measured in the same manner as above. The results are shown in Table 1 as adhesive strength after UV irradiation.

[0097] [Test Example 3] (Measurement of the amount of silicon atoms transferred) The release sheets were peeled off from the workpiece processing sheets produced in the Examples and Comparative Examples, and the amount of silicon atoms (cps) transferred from the release sheet to the adhesive surface of the exposed adhesive layer was measured using an X-ray fluorescence analyzer (manufactured by Rigaku Corporation, product name "Mini-Z"). The results are shown in Table 1.

[0098] [Test Example 4] (Measurement of Surface Roughness) The release sheet was peeled from the workpiece processing sheets produced in the Examples and Comparative Examples, and the release sheet was separated from the adhesive sheet. Then, the arithmetic mean height Ra (μm) of the release surface of the release sheet was measured using a contact surface roughness meter (manufactured by Mitutoyo Corporation, product name "SV-3000") in accordance with JIS B0601:2013 under the following conditions. The results are shown in Table 1. <Measurement Conditions> Test piece size: 5 cm x 5 cm release sheet Reference length of roughness curve: 0.25 mm Measurement speed: 0.5 mm / s N number: 3 (the average value was calculated from three measured values)

[0099] Furthermore, the arithmetic mean height Sa (μm) of the adhesive surface of the adhesive sheet obtained by separation as described above was measured using a non-contact surface measurement system in accordance with ISO 25178. The results are shown in Table 1.

[0100] The non-contact surface measurement system used was a non-contact surface measurement system (manufactured by Hitachi High-Tech Science Corporation, product name "Vertscan") that uses direct phase detection interferometry, or so-called two-beam interferometry utilizing Michelson interference.

[0101] [Test Example 5] (Measurement of particle amount) The release sheets of the workpiece processing sheets according to the Examples and Comparative Examples, which were produced in a clean room, were peeled off 24 hours after production to expose the adhesive layer. The exposed surface of the adhesive layer was then placed on the mirror surface of a 6-inch silicon wafer, which had been confirmed in advance to have 30 or less particles on its surface, and the wafer was bonded to the mirror surface by rolling a 5 kg roller back and forth once to apply a load, thereby preparing a test sample.

[0102] The test sample was stored in a clean room for 24 hours after lamination, and then the surface of the substrate side was irradiated with ultraviolet (UV) light (illuminance: 230 mW / cm) under nitrogen using an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2010"). ２ , Light amount: 180mJ / cm ２ ) was carried out to cure the adhesive layer.

[0103] Next, with the silicon wafer side of the test sample fixed to the suction table, the workpiece processing sheet (an adhesive sheet consisting of a base material and an adhesive layer) was peeled off at a peel angle of 180° at a constant speed without stopping midway.

[0104] Then, after peeling off the workpiece processing sheet, the mirror surface of the silicon wafer was counted for the number of particles with a particle size of 0.270 μm or less using a laser surface inspection device (manufactured by Hitachi High-Tech Corporation, product name "LS6600"). The results are shown in Table 1. All of the above steps were carried out in a clean environment in a clean room.

[0105] [Test Example 6] (Evaluation of chipping) One side of a silicon wafer was ground to a thickness of 150 μm using a grinder (manufactured by Disco Corporation, product name "DFG8540"), and the exposed surface of the adhesive layer exposed by peeling the release sheet from the workpiece processing sheet produced in the Examples and Comparative Examples was attached to the ground surface using a laminator.

[0106] Twenty minutes after application, the silicon wafer was divided into chips by dicing under the following dicing conditions using a dicing device (manufactured by Disco Corporation, product name "DFD6362"). The number of chips that broke off after dicing was then counted. The results are shown in Table 1. Dicing conditions Chip size: 2 mm x 2 mm Cutting height: 60 μm (substrate thickness: 80 μm) Blade rotation speed: 35,000 rpm Cutting speed: 50 mm / sec Blade: manufactured by Disco Corporation, product name "NBC-2H 2050 27HECC"

[0107] [Test Example 7] (Evaluation of Pickup Property) One side of a silicon wafer was ground to a thickness of 150 μm using a grinder (manufactured by Disco Corporation, product name "DFG8540"), and the exposed surface of the pressure-sensitive adhesive layer exposed by peeling the release sheet from the workpiece processing sheet produced in the Examples and Comparative Examples was attached to the ground surface using a laminator to prepare a measurement sample.

[0108] The measurement sample was stored for 7 days under conditions of a temperature of 23°C and a relative humidity of 50%, and then diced using a dicing device (manufactured by Disco Corporation, product name "DFD6362") under the following dicing conditions: Dicing conditions: Chip size: 10 mm x 10 mm Cutting height: 60 μm (substrate thickness: 80 μm) Blade rotation speed: 35,000 rpm Cutting speed: 50 mm / sec Blade: manufactured by Disco Corporation, product name "NBC-2H 2050 27HECC"

[0109] Next, the substrate side of the workpiece processing sheet was irradiated with ultraviolet (UV) light (illuminance: 230 mW / cm) under nitrogen using an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2010"). ２ , Light amount: 180mJ / cm ２ ) was carried out to cure the adhesive layer.

[0110] Next, in an atmospheric environment, a pickup device was used to pick up chips located near the center of the workpiece processing sheet. <Pickup conditions> Collet pressure: 0.8 N Pickup method: 4 pins Pin push-up speed: 5 mm / s Pin push-up height: 100 to 600 μm

[0111] The push-up height was increased by 50 μm from 100 μm. Five chips were picked up at each push-up height. The minimum push-up height (μm) was recorded when all five chips were successfully picked up. The results are shown in Table 1.

[0112]

[0113] As can be seen from Table 1, the workpiece processing sheet obtained in the examples significantly reduced carbon dioxide emissions when the release sheet was discarded compared to Comparative Example 1, which used a resin release substrate. Furthermore, the workpiece processing sheet obtained in the examples was found to reduce the amount of particles adhering to the silicon wafer compared to Comparative Example 2, which used a plain paper release substrate, and to have almost no adverse effects on workpiece processing. With the workpiece processing sheet in Comparative Example 2, dust generated from the plain paper was dispersed into the workpiece processing environment, contaminating the workpiece after tape removal, which is expected to result in an increased amount of particles. Furthermore, the workpiece processing sheet obtained in the examples was able to suppress chip flying during dicing and reduce the minimum lift height during pickup.

[0114] Furthermore, when focusing on the arithmetic mean height Ra of the peeled surface, Example 1, which was produced using the ultra-mirror roll, had the smallest Ra. Furthermore, it was found that Examples 1 and 2, which used glassine paper, had smaller Ra and were smoother than Comparative Example 2, which used plain paper. Furthermore, a tendency for Ra to be smaller was confirmed in Examples 1 and 2, which were provided with a polyethylene laminate layer.

[0115] It was also found that in examples where the release surface was smooth, the arithmetic mean height Sa of the adhesive surface also tended to be smaller. A smooth adhesive surface like this facilitates stable attachment to the workpiece. Regarding the arithmetic mean height Sa of the adhesive surface, differences were observed between examples using plain paper and examples using glassine paper, with smaller Sa in Examples 1 and 2. Similarly, differences were observed depending on whether or not a polyethylene laminate layer was present, with examples with a polyethylene laminate layer tending to have smaller Sa. Meanwhile, regarding the difference between the ultra-mirror and semi-mirror surfaces, while differences were observed in the Ra of the release surface, no significant difference was observed in the Sa of the adhesive surface.

[0116] The workpiece processing sheet of the present invention can be suitably used for processing workpieces such as semiconductor wafers.

Claims

1. A workpiece processing sheet comprising: a release sheet having a release agent layer on one side of glassine paper; and a workpiece attachment layer laminated on the side of the release agent layer opposite the glassine paper.

2. The workpiece processing sheet according to claim 1, characterized in that the release sheet comprises a polyethylene laminate layer laminated between the glassine paper and the release agent layer.

3. A workpiece processing sheet according to claim 1, characterized in that the arithmetic mean height Ra of the surface of the release sheet facing the release agent layer is 0.01 μm or more and 2.0 μm or less.

4. A workpiece processing sheet as described in claim 1, characterized in that, in a clean environment, the release sheet is peeled off from the workpiece processing sheet and the exposed surface of the workpiece attachment layer is attached to the mirror surface of a silicon wafer, and after storing for 24 hours, the number of particles with a particle size of 0.270 μm or less adhering to the mirror surface exposed by peeling off the workpiece attachment layer is 500 or less.

5. The workpiece processing sheet according to claim 1, wherein the workpiece attachment layer is at least one of an adhesive layer, a bonding agent layer, and a protective film forming layer.

6. The workpiece processing sheet according to claim 1, characterized in that the workpiece processing sheet is at least one of a dicing sheet, a back grinding sheet, an expanding sheet, a die bonding sheet, a back surface protection sheet, and a bump surface protection sheet.

7. A method for manufacturing a semiconductor device, comprising the steps of: peeling the release sheet from the workpiece processing sheet according to any one of claims 1 to 6 to attach one or more workpieces to the exposed surface of the workpiece attachment layer; and separating at least one of the workpieces from the workpiece attachment layer and placing it on a predetermined object.

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