Method for manufacturing workpiece processing sheets and semiconductor devices

Abstract

We provide a workpiece processing sheet that can significantly contribute to reducing carbon dioxide emissions and the use of plastic materials. [Solution] A workpiece processing sheet comprising a release sheet having glassine paper, a clay coat layer laminated on one side of the glassine paper, a release agent layer laminated on the side of the clay coat layer opposite to the glassine paper, and a workpiece attachment layer laminated on the side of the release agent layer opposite to the clay coat layer, wherein the release sheet does not have a polyethylene laminate layer.

Description

[Technical Field]

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

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

[0003] The workpiece processing sheet described above generally comprises a base material and a workpiece attachment layer laminated on one side of the base material. Depending on the application of the workpiece processing sheet, the workpiece attachment layer may include an adhesive layer, a bonding layer, or a protective film-forming layer.

[0004] In workpiece processing sheets, a release sheet is usually laminated on the side facing the workpiece attachment layer to protect that side until it is attached to the workpiece. For example, Patent Document 1 discloses an adhesive sheet in which a release sheet is laminated on the side facing the adhesive layer in a laminate of a substrate and an adhesive layer.

[0005] A release sheet generally consists of a release agent layer formed on one side of a release substrate. Conventionally, 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. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2010-168541 [Overview of the project] [Problems that the invention aims to solve]

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

[0008] From this perspective, there is consideration to replacing plastic release substrates with paper ones. However, even when using paper release substrates, a resin layer (for example, a polyethylene laminate layer) is usually formed between the release substrate and the release agent layer to prevent the components of the release agent layer formed on its surface from penetrating the release substrate. Such a resin layer naturally increases carbon dioxide emissions.

[0009] This invention has been made in view of the above circumstances, and aims to provide a workpiece processing sheet that can make a significant contribution to reducing carbon dioxide emissions and the use of plastic materials. [Means for solving the problem]

[0010] To achieve the above objective, firstly, the present invention provides a workpiece processing sheet comprising a release sheet comprising glassine paper, a clay coat layer laminated on one side of the glassine paper, a release agent layer laminated on the side of the clay coat layer opposite to the glassine paper, and a workpiece attachment layer laminated on the side of the release agent layer opposite to the clay coat layer, wherein the release sheet does not have a polyethylene laminate layer (Invention 1).

[0011] The workpiece processing sheet according to the above-mentioned invention (Invention 1) uses glassine paper as the release base material of the release sheet, and is provided with a clay coat layer between the release base material and the release agent layer, whereby carbon dioxide emissions can be reduced and the amount of plastic material used can be lowered while sufficiently ensuring the function as a release sheet.

[0012] In the above-mentioned invention (Invention 1), the clay coat layer preferably contains kaolin (Invention 2).

[0013] In the above-mentioned inventions (Inventions 1 and 2), the workpiece adhesion layer is preferably at least one selected from a pressure-sensitive adhesive layer, an adhesive layer, and a protective film-forming layer (Invention 3).

[0014] In the above-mentioned inventions (Inventions 1 to 3), the workpiece processing sheet is preferably at least one selected from a dicing sheet, a back grind sheet, an expanding sheet, a die bond sheet, a back surface protection sheet, and a bump surface protection sheet (Invention 4).

[0015] Secondly, the present invention provides a method for manufacturing a semiconductor device, characterized by comprising: a step of attaching one or a plurality of workpieces to the exposed surface of the workpiece adhesion layer exposed by peeling the release sheet from the workpiece processing sheet (Inventions 1 to 4); and a step of separating at least one of the workpieces from the workpiece adhesion layer and placing the separated workpiece on a predetermined target (Invention 5). [Effects of the Invention]

[0016] The workpiece processing sheet according to the present invention can greatly contribute to the reduction of carbon dioxide emissions and the reduction of the use of plastic materials. [Mode for Carrying Out the Invention]

[0017] Embodiments of the present invention will be described below. The workpiece processing sheet according to this embodiment comprises a release sheet and a workpiece adhesion layer. The release sheet comprises glassine paper, a clay coat layer laminated on one side of the glassine paper, and a release agent layer laminated on the side of the clay coat layer opposite to the glassine paper. The workpiece adhesion layer is laminated on the side of the release agent layer opposite to the clay coat layer. Furthermore, the release sheet does not have a polyethylene laminate layer.

[0018] In this embodiment, the release sheet uses glassine paper as the release substrate, allowing it to perform at the same level as a typical release sheet using a resin-based release substrate. In particular, glassine paper generates significantly less dust and debris compared to ordinary paper, thus suppressing contamination of the workpiece processing sheet, the workpiece itself, and the equipment handling the workpiece processing sheet by dust and debris.

[0019] Furthermore, the workpiece processing sheet according to this embodiment uses glassine paper as a release substrate, which significantly reduces the amount of carbon dioxide emitted when the release sheet is discarded and also reduces the amount of plastic material used. In particular, glassine paper emits less carbon dioxide when burned compared to general resin films. Moreover, glassine paper is basically made from biomass, and the amount of carbon dioxide absorbed by the raw material plants can be offset from the amount of carbon dioxide emitted when burned. As a result, the actual carbon dioxide emissions from glassine paper are significantly lower than those from general resin films.

[0020] Furthermore, the release sheet in this embodiment includes a clay coat layer between the release substrate and the release agent layer, and does not include a polyethylene laminate layer. The clay coat layer is mainly formed from clay components and contains no organic compounds, or only a small amount, so there is almost no carbon dioxide emission from the clay coat layer when the release sheet is discarded. On the other hand, the clay coat layer can sufficiently prevent the components of the release agent layer from penetrating into the release substrate. As a result, the release sheet in this embodiment, despite not having a polyethylene laminate layer, achieves sufficient prevention of release agent component penetration while significantly reducing carbon dioxide emissions.

[0021] Based on the above, by using the workpiece processing sheet according to this embodiment as a substitute 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 impairing the function of the workpiece processing sheet.

[0022] Furthermore, while the use of paper substrates has been considered as the release substrate for release sheets in the past, the glassine paper used in the workpiece processing sheet according to this embodiment has several advantages compared to ordinary paper used as such a paper substrate. Advantages over ordinary paper include, as mentioned above, that it is less prone to generating dust and dirt, as well as its high smoothness. This makes it easier to improve the smoothness of the release sheet itself, and consequently, the smoothness of the surface of the workpiece attachment layer attached to the release sheet is also improved. As a result, using the workpiece processing sheet according to this embodiment enables highly accurate workpiece processing.

[0023] Furthermore, glassine paper has higher strength than ordinary paper, making it possible to produce longer lengths of workpiece processing sheets, thus reducing production costs. In addition, glassine paper has superior water and oil resistance compared to ordinary paper, making it less susceptible to external environmental factors such as humidity, and thus easier to stabilize quality. Moreover, glassine paper has higher transparency than ordinary paper, which offers the advantage of better recognition by sensors in equipment that handles glassine paper and workpiece processing sheets.

[0024] 1. Release sheet (1) Glassine paper The glassine paper in this embodiment is not particularly limited, and known types can be used. The pulp constituting the glassine paper can be known, and for example, wood pulps such as softwood kraft pulp (N material), hardwood kraft pulp (L material), softwood sulfite pulp, hardwood sulfite pulp, dissolved pulp, and mercerized pulp, as well as non-wood pulps such as flax pulp, Manila hemp pulp, and kenaf pulp can be used. 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.

[0025] When using a combination of softwood kraft pulp and hardwood kraft pulp, it is preferable to use them in a ratio of softwood kraft pulp to hardwood kraft pulp of 5:95 to 50:50, and particularly preferable to use them in a ratio of 15:85 to 40:60.

[0026] Furthermore, the glassine paper in this embodiment may have various additives added to the pulp, examples of which include fillers, wet strength enhancers, dry strength enhancers, sizing agents, aluminum sulfate, various yield enhancers of anionic, cationic, nonionic, and amphoteric types, water drainage enhancers, color dyes, color pigments, fluorescent whitening agents, pH adjusters, defoamers, pitch control agents, slime control agents, and the like.

[0027] The method for beating the pulp as described above is not particularly limited, and it can be beating using a known refiner or the like. Then, by processing the beating pulp under high pressure using a smooth roller such as a supercalender, the glassine paper of this embodiment can be obtained.

[0028] The basis weight of the glassine paper in this embodiment is 30 g / m². 2 It is preferable that the amount be greater than or equal to 40 g / m², and particularly 40 g / m². 2 Preferably, it is 45 g / m² or more, and more preferably 45 g / m² 2 It is preferable that the basis weight is 150 g / m². 2 Preferably, it is 120 g / m² or less, and especially 120 g / m². 2 Preferably the following, and moreover 100g / m 2 The following is preferable: When the basis weight of the glassine paper is within the above range, the release sheet will have sufficient strength while also being easy to handle.

[0029] 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. When the thickness of the glassine paper is within the above range, the release sheet has sufficient strength while also being easy to handle.

[0030] (2) Clay coat layer As described above, the clay coat layer in this embodiment is composed of clay components. Examples of clay components that can be used include kaolin, talc, bentonite, smectite, vermiculite, mica, chlorite, kibushi clay, gailome clay, halloysite, etc. Among these, kaolin is preferred because it is easier to produce a smoother film as a coat layer.

[0031] The shape of the clay component is not particularly limited, but from the viewpoint of smoothness, it is preferably flat and plate-like. The average particle size of the clay component is also not particularly limited, but is preferably, for example, 0.1 to 10 μm. This average particle size is volume-based and can be measured using a laser diffraction particle size distribution analyzer.

[0032] When the clay component has a flattened plate-like shape, the ratio of the average particle size to the average thickness, i.e., the aspect ratio, is preferably 3.0 or higher, more preferably 5.0 or higher, and even more preferably 7.0 or higher. The upper limit of the aspect ratio of the clay component may be 10.0 or lower.

[0033] The clay content in the clay coat layer is preferably, for example, 60 to 85% by mass, and particularly preferably 70 to 80% by mass.

[0034] The clay coat layer may contain components other than clay. Examples of such components include oxidized starch, resin components, pigments, pigment dispersants, defoamers, anti-foaming agents, viscosity modifiers, lubricants, water-resistant agents, water-retaining agents, and colorants.

[0035] The above resin components are preferred because they facilitate the achievement of excellent film-forming properties. Examples of resin components include copolymers such as styrene-butadiene copolymer, styrene-acrylic copolymer, ethylene-vinyl chloride copolymer, methyl methacrylate-butadiene copolymer, ethylene-vinyl acetate copolymer, and (meth)acrylic acid ester copolymer; and water-soluble resins such as casein, dextrin, starch, oxidized starch, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, and polyvinyl alcohol. These binder resins may be used alone or in combination of two or more.

[0036] Among the resin components mentioned above, it is preferable that the resin contains a styrene-butadiene copolymer in terms of film-forming properties. Furthermore, the styrene-butadiene resin (styrene-butadiene copolymer) is preferably of the latex type (styrene-butadiene rubber latex) due to its high solids content, low viscosity, and excellent productivity. The glass transition temperature of the styrene-butadiene resin is preferably between -50°C and 50°C, and more preferably between -20°C and 20°C, in terms of ease of smoothing by pressurization in the supercalendering process. The minimum film-forming temperature of the latex type (styrene-butadiene rubber latex) is preferably in the range of 10 to 150°C. The minimum film-forming temperature is the lowest temperature required for a continuous film to be formed when the moisture in the styrene-butadiene rubber latex evaporates and dries, and is obtained by the temperature gradient plate method. Commercially available latex types of styrene-butadiene copolymers may be used, such as Smartex® SN-309R (styrene-butadiene rubber latex, manufactured by A&L Japan, glass transition temperature 4°C), Smartex® SN-307R (styrene-butadiene rubber latex, manufactured by A&L Japan, glass transition temperature 10°C), and JSR0693 (styrene-butadiene rubber latex, manufactured by JSR Corporation, glass transition temperature 20°C).

[0037] The clay coat layer preferably contains, among the above-mentioned components, oxidized starch, polyvinyl alcohol, and styrene-butadiene resin as components other than clay. Using these components makes it easier to achieve excellent film-forming properties, improves the adhesion between the clay coat layer and the release agent layer, and also improves processability.

[0038] As a method for forming the clay coat layer, for example, a composition containing the clay component or other components mentioned above can be prepared and applied to one side of the release substrate. If necessary, the composition may be dissolved and dispersed in a solvent such as water to prepare a coating solution, and the clay coat layer may be formed by applying this coating solution.

[0039] In the present embodiment, the thickness of the clay coat layer is preferably 2 µm or more, particularly preferably 3 µm or more, and further preferably 4 µm or more. Also, the thickness is preferably 20 µm or less, particularly preferably 15 µm or less. The coating amount of the composition for forming the clay coat layer is 2 g / m 2 or more, preferably 3 g / m 2 or more, more preferably 4 g / m 2 or more. Also, the coating amount is 20 g / m 2 or less, preferably 16 g / m 2 or less. When the thickness of the clay coat layer and the coating amount of the composition fall within the above ranges, it becomes easier to more effectively suppress the penetration of the release agent component into the release base material, and the smoothness of the release surface of the release sheet is further improved. Furthermore, an excessive increase in the total thickness of the entire workpiece processing sheet is suppressed, making it easy to maintain handling properties similar to those of conventional plastic film release films.

[0040] (3) Release Agent Layer The release agent constituting the release agent layer in the present embodiment is not particularly limited, and any general release agent used for release sheets can be used. As the above release agent, silicone-based release agents, fluorine-based release agents, long-chain alkyl release agents, rubber-based release agents and the like can be appropriately used, and among these, silicone-based release agents are preferable because they can provide inexpensive and stable performance.

[0041] The release agent layer in the present embodiment can be formed by a general method. For example, when forming a release agent layer using a silicone-based release agent, a release agent composition serving as a material of the silicone-based release agent is applied to the surface of the clay coat layer opposite to glassine paper, and the obtained coating film is subjected to treatment such as heating to be cured, whereby the release agent layer can be obtained.

[0042] The basis weight of the release agent layer in the present embodiment is 0.1 g / m2 Preferably, the value is 0.3 g / m² or higher, and especially 0.3 g / m². 2 It is preferable that the above is true. Furthermore, the basis weight is 1.5 g / m². 2 Preferably, it is 1.0 g / m² or less, and especially 1.0 g / m². 2 The following is preferable: When the basis weight of the release agent layer is within the above range, it becomes easier to form a release agent layer that exhibits good release properties.

[0043] 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 200 nm or more. Furthermore, the thickness is preferably 1000 nm or less, particularly preferably 800 nm or less, and even more preferably 700 nm or less. Having the thickness of the release agent layer within the above range makes it easier to form a release agent layer that exhibits good release properties.

[0044] (4) PVA coating layer In this embodiment, it is also preferable that the release sheet includes a PVA coating layer between the release substrate and the clay coating layer. The presence of the PVA coating layer makes it easier to more effectively suppress the penetration of release components into the release substrate and further improves the adhesion between the release substrate and the clay coating layer.

[0045] The composition of the PVA coating layer is not particularly limited as long as it contains polyvinyl alcohol (PVA). The degree of saponification of the polyvinyl alcohol is preferably 80 to 100 mol%, and particularly preferably 85 to 100 mol%. The weight-average molecular weight of the polyvinyl alcohol is preferably 5,000 to 150,000, and particularly preferably 10,000 to 100,000. In this specification, the weight-average molecular weight (Mw) is the value on a standard polystyrene basis measured by gel permeation chromatography (GPC).

[0046] In addition to polyvinyl alcohol, other components that can be used in the PVA coating layer include fillers such as clay, silica, calcium carbonate, titanium dioxide, and zinc oxide, as well as dispersants, thickeners, defoamers, anti-foaming agents, viscosity modifiers, lubricants, water-resistant agents, water-retaining agents, and colorants.

[0047] One method for forming the PVA coating layer is to prepare a composition containing the polyvinyl alcohol and other components mentioned above, and apply the composition to one side of the release substrate. If necessary, the composition may be dissolved and dispersed in a solvent such as water to prepare a coating solution, and the PVA coating layer may be formed by applying this coating solution.

[0048] In this embodiment, the amount of the above composition applied to the PVA coating layer is 0.2 to 4.0 g / m². 2 Preferably, it is 0.5 to 3.0 g / m². 2 It is preferable that the thickness of the PVA coating layer is within the above range, which makes it easier to more effectively suppress the penetration of the release agent component into the release substrate and to further improve the adhesion between the release substrate and the clay coating layer.

[0049] (5) Surface roughness In this embodiment, the release sheet preferably exhibits the following surface roughness on its release surface. Specifically, the arithmetic mean roughness 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 roughness Ra of the release surface is within the above range, the release surface becomes smoother, and the smoothness of the workpiece adhesive layer laminated on the release surface becomes even better. As a result, it becomes easier to perform high-precision workpiece processing using the workpiece processing sheet according to this embodiment. The lower limit of the arithmetic mean roughness Ra is not particularly limited, and may be, for example, 0.01 μm or more, particularly 0.05 μm or more, and even more preferably 0.1 μm or more.

[0050] The details of the measurement method for the arithmetic mean roughness Ra described above are as follows. First, the release sheet is peeled off from the workpiece processing sheet in this embodiment, separating the release sheet from the adhesive sheet. Then, the arithmetic mean roughness Ra (μm) of the peeled surface of the release sheet can be measured using a contact-type surface roughness meter in accordance with JIS B0601:2013. The measurement conditions for this measurement are as follows. <Measurement conditions> Test specimen size: 5cm x 5cm release sheet Reference length of roughness curve: 0.25 mm Measurement speed: 0.5mm / s N: 3 (calculate the average value from 3 measurements)

[0051] 2. Workpiece bonding layer The workpiece attachment layer in this embodiment 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 an adhesive layer, a bonding layer, and a protective film forming layer. These layers can be appropriately selected depending on the application of the workpiece processing sheet.

[0052] In this embodiment, the workpiece processing sheet is preferably used as at least one of the following: a dicing sheet, a back grind sheet, an expanded sheet, a die bond sheet, a back surface protection sheet, and a bump surface protection sheet. Of these, if the workpiece processing sheet is a dicing sheet, a back grind sheet, or an expanded sheet, the workpiece attachment layer is preferably an adhesive layer. If the workpiece processing sheet is a die bond sheet, the workpiece attachment layer is preferably an adhesive layer. Furthermore, if 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.

[0053] (1) Adhesive layer As the adhesive layer mentioned above, a common adhesive layer used for dicing sheets, backgrind sheets, expanded sheets, etc., can be used. As the adhesive constituting the adhesive layer, for example, acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, etc., can be used. Among these, acrylic adhesives are preferred from the viewpoint of easily exhibiting the desired adhesive strength.

[0054] Furthermore, the adhesive constituting the adhesive layer may be one that does not have active energy ray curability, one that has active energy ray curability, one that is heat-foaming, or one that has the property of foaming when exposed to active energy rays. Among these, one that has active energy ray curability is preferred. By using an active energy ray curable adhesive, the adhesive layer can be cured by irradiation with active energy rays, making it possible to easily separate the workpiece from the adhesive layer.

[0055] The above-mentioned active energy ray curable adhesive may be mainly composed of a polymer having active energy ray curability, or it may be mainly composed of a mixture of an active energy ray non-curable polymer (a polymer that does not have active energy ray curability) and a monomer and / or oligomer having at least one active energy ray curable group. Alternatively, 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.

[0056] The polymer having active energy ray curability described above is preferably a (meth)acrylic acid ester polymer (hereinafter sometimes referred to as "active energy ray curable polymer") in which a functional group having active energy ray curability (active energy ray curable group) is introduced into the 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 that functional group. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the concept of "polymer" is also included in the concept of "copolymer".

[0057] The acrylic polymer having the functional group-containing monomer units described above may be obtained by polymerizing the functional group-containing monomer together with other monomers. Known functional group-containing monomers and other monomers, as well as the unsaturated group-containing compounds described above, can be used, for example, those disclosed in International Publication No. 2018 / 084021.

[0058] 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 even more preferably 200,000 or more. Furthermore, the weight-average molecular weight is preferably 1,500,000 or less, and particularly preferably 1,000,000 or less.

[0059] As the above-mentioned active energy ray non-curable polymer, for example, the (meth)acrylic acid ester polymer before reacting with the unsaturated group-containing compound can be used.

[0060] The weight-average molecular weight of the (meth)acrylic acid ester polymer, which is the above-mentioned active energy ray noncurable polymer, is preferably 10,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more. Furthermore, the weight-average molecular weight is preferably 1,500,000 or less, and particularly preferably 1,000,000 or less.

[0061] Furthermore, as monomers and / or oligomers having at least one active energy ray curable group as described above, for example, esters of polyhydric alcohols and (meth)acrylic acid can be used.

[0062] It is also preferable to add a crosslinking agent to the above-mentioned active energy ray-curable adhesive. By using a crosslinking agent, the active energy ray-curable adhesive is more likely to have the desired cohesive force. As the crosslinking agent, a polyfunctional compound that has reactivity with the functional groups of the active energy ray-curable adhesive 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 can be appropriately determined, for example, in the range of 1 to 15 parts by mass per 100 parts by mass of the active energy ray-curable adhesive.

[0063] Furthermore, when ultraviolet light is used as the active energy ray for curing an active energy ray-curable adhesive, it is preferable to add a photopolymerization initiator to the adhesive. By using a photopolymerization initiator, it is possible to effectively reduce the polymerization curing time and the amount of light irradiation required for the adhesive, especially when ultraviolet light is used as the active energy ray.

[0064] In this embodiment, when the workpiece attachment layer is an adhesive layer, the thickness of the adhesive layer is preferably 3 to 50 μm, particularly preferably 5 to 40 μm, and even more preferably 10 to 20 μm. Having the adhesive layer thickness within this range makes it easier for the workpiece attachment layer to exhibit the desired adhesive strength.

[0065] (2) Adhesive layer When the workpiece attachment layer in this embodiment is an adhesive layer, as described above, the workpiece processing sheet according to this embodiment is typically used as a die bond sheet. Therefore, there are no particular restrictions on the material that constitutes the adhesive layer, as long as it can form an adhesive layer on the workpiece.

[0066] Materials used to constitute such adhesive layers include those consisting of a thermoplastic resin and a low molecular weight thermosetting adhesive component, or those consisting of a B-stage (semi-cured) thermosetting adhesive component. Among these, it is preferable that the materials constituting the adhesive layer include 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 tackiness and film-forming properties (sheet processability). Examples of thermosetting adhesive components include epoxy resins, polyimide resins, phenolic resins, silicone resins, cyanate resins, bismaleimidotriazine resins, allylated polyphenylene ether resins (thermosetting PPE), formaldehyde resins, unsaturated polyesters, or copolymers thereof. Among these, epoxy resins are preferred from the viewpoint of adhesion.

[0067] In this embodiment, when the workpiece attachment layer is an adhesive layer, the thickness of the adhesive layer can be appropriately selected depending on the purpose, and for example, it is preferably 1 to 50 μm, particularly preferably 3 to 25 μm, and even more preferably 5 to 20 μm.

[0068] (3) Protective film forming layer In this embodiment, if the workpiece attachment layer is a protective film forming layer, it is preferable that the protective film forming layer is made of an uncured curable adhesive. In this case, after stacking a workpiece such as a semiconductor wafer or semiconductor chip 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.

[0069] The protective film-forming layer is preferably adhesive at room temperature or exhibits adhesiveness upon heating. This allows the workpiece to be bonded to the protective film-forming layer when it is placed on top of it, 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. As the curable component, a thermosetting component, an energy ray curable component, or a mixture thereof can be used. From the viewpoint of the curing method of the protective film-forming layer and the heat resistance after curing, the use of a thermosetting component is particularly preferred, and from the viewpoint of curing time, the use of an energy ray curable component is preferred.

[0070] In this embodiment, when the workpiece attachment layer is a protective film forming layer, the thickness of the protective film forming layer can be appropriately selected depending on the purpose. For example, it is preferably 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. Moreover, when used in a process to fill grooves in a workpiece having grooves on its surface with a protective film forming layer, 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.

[0071] (4) Layer composition The workpiece processing sheet according to this embodiment may include other components as appropriate, depending on the application of the workpiece processing sheet and the specific type of workpiece adhesive layer.

[0072] For example, when a workpiece processing sheet is used as a dicing sheet, backgrinding sheet, or expandable sheet, and the workpiece attachment layer is an adhesive layer, it is preferable that a base material is laminated on the side of the workpiece attachment layer (adhesive layer) opposite to the release sheet. By providing a base material, when the release sheet is peeled off from the workpiece processing sheet, the workpiece attachment layer is supported by the base material, making it easier to process the workpiece on the workpiece attachment layer.

[0073] Furthermore, even when a workpiece processing sheet is used as a die bond sheet and the workpiece attachment layer is an adhesive layer, it is preferable that the base material is laminated on the side of the workpiece attachment layer (adhesive layer) opposite to the release sheet. By providing a base material, the workpiece attachment layer is supported by the base material, making it easier to laminate the adhesive layer onto the workpiece smoothly.

[0074] Furthermore, in the case where the workpiece processing sheet is a back-side protective sheet and the workpiece attachment layer is a protective film forming layer, in the first embodiment, it is preferable that an adhesive layer is laminated on the side of the workpiece attachment layer (protective film forming layer) opposite to the release sheet, and a base material is laminated on the side of the adhesive layer opposite to the workpiece attachment layer. In this configuration, the workpiece attachment layer, adhesive layer, and base material are laminated in order to the release sheet, making it easier to transfer the workpiece attachment layer (protective film forming layer) to the target workpiece. In the second embodiment, it is also preferable that another release sheet is laminated on the side of the workpiece attachment layer (protective film forming layer) opposite to the release sheet. In such a case, the workpiece processing sheet can transfer the protective film forming layer to the workpiece without a base material.

[0075] Furthermore, 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 is laminated on the side of the workpiece attachment layer (protective film forming layer) opposite to the release sheet, a buffer layer is laminated on the side of the intermediate release agent layer opposite to the workpiece attachment layer, and a base material is laminated on the side of the buffer layer opposite to the intermediate release layer. With this configuration, it becomes easier to transfer the workpiece attachment layer (protective film forming layer) to the target bumped workpiece.

[0076] The aforementioned substrates may be any known materials, depending on the purpose, and for example, it is preferable to use a resin film.

[0077] 3. Method for manufacturing workpiece processing sheets The method for manufacturing the workpiece processing sheet according to this embodiment is not particularly limited. For example, a workpiece adhesive layer can be formed on the release surface of the release sheet manufactured as described above, and then, if necessary, a base material or the like can be laminated on the side of the workpiece adhesive layer opposite to the release sheet to obtain the desired workpiece processing sheet.

[0078] The workpiece adhesion layer on the release surface of the release sheet can be formed by known methods. For example, when forming an adhesive layer as the workpiece adhesion layer, a coating liquid containing an adhesive composition constituting the adhesive layer, and optionally a solvent or dispersion medium, can be prepared. This coating liquid can then be 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 can be dried to form the adhesive layer. The properties of the coating liquid are not particularly limited as long as it can be applied, and it may contain components for forming the adhesive layer as a solute or as a dispersed phase.

[0079] If the coating liquid for forming the adhesive layer contains a crosslinking agent, the crosslinking reaction between the active energy ray-curable polymer and the crosslinking agent in the coating film can be promoted by changing the drying conditions (temperature, time, etc.) or by providing a separate heat treatment, thereby forming a crosslinked structure with a desired density in the adhesive layer. To ensure this crosslinking reaction progresses sufficiently, after laminating the adhesive layer onto the substrate by the method described above, the resulting workpiece processing sheet may be cured by, for example, leaving it undisturbed in an environment of 23°C and 50% relative humidity for several days.

[0080] 4. How to use the workpiece processing sheet The workpiece processing sheet according to this embodiment can be used for processing workpieces. That is, the release sheet can be peeled off from the workpiece processing sheet according to this embodiment, and the exposed surface of the workpiece adhesive layer that is thus exposed can be attached to one side of the workpiece, and then the workpiece can be processed on the workpiece processing sheet.

[0081] Examples of the above processing include dicing, back grinding, expanding, picking, die bonding, back surface protection, bump surface protection, etc.

[0082] The workpiece processed using the workpiece processing sheet according to this embodiment is not particularly limited and includes, for example, semiconductor wafers, semiconductor packages and other semiconductor components, and glass plates and other glass components.

[0083] When the semiconductor material described above is used as the workpiece, the workpiece processing sheet according to this embodiment is also preferably used in a method for manufacturing a semiconductor device. This manufacturing method includes, for example, the steps of peeling off the release sheet from the workpiece processing sheet according to this embodiment and attaching 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. The above-described attachment and separation can be carried out using known methods.

[0084] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Accordingly, 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. [Examples]

[0085] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0086] [Example 1] 1. Making glassine paper Bleached hardwood kraft pulp (LBKP) was beaten in water using the Schoper-Rigler method to achieve a beat degree of 42°SR, and this was dispersed in water to obtain a pulp dispersion with a concentration of approximately 1.0% by mass. To 100 parts by mass of pulp in this dispersion, 0.4 parts by mass of rosin sizing agent and 0.2 parts by mass of aluminum sulfate as a fixing agent were added to obtain a pulp slurry. Next, this pulp slurry was used to make paper using a long-wire multi-cylinder paper machine to obtain a release substrate with a basis weight of 62 g / m². 2 Glassine paper was obtained. The thickness of the glassine paper was 49 μm.

[0087] 2. Formation of the clay coat layer On one side of the glassine paper obtained in step 1 above, a composition containing polyvinyl alcohol (PVA, saponification degree 98 mol%, molecular weight 75,000) and water, each in a predetermined ratio, is applied at a rate of 1.0 g / m². 2 A PVA coating layer was formed by applying the material in this manner and allowing it to dry. The thickness of the formed PVA coating layer was 1 μm.

[0088] Next, a coating solution was prepared containing flattened kaolin (average particle size: 4.3 μm) and polyvinyl alcohol (saponification degree: 98 mol, molecular weight: 75,000) in an 8:2 ratio (by solid content mass), with water as the solvent in a predetermined proportion.

[0089] Next, the above coating liquid is applied at a rate of 17.5 g / m². 2 The clay coat layer was formed by applying it to a PVA coating layer, drying it, and then passing it through a supercalender roll. The thickness of the formed clay coat layer was 5 μm.

[0090] 3. Preparation of the release sheet On the clay coat layer formed in step 2 above, apply a silicone-based release agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KNS-3051") at a rate of 1.7 g / m². 2 The material was applied in this manner and then heated at 150°C for 30 seconds to cure it, thereby forming a release agent layer. This resulted in a release sheet in which a PVA coating layer, a clay coating layer, and a release agent layer were sequentially laminated on glassine paper.

[0091] 4. Preparation of workpiece processing sheets 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) in an amount equivalent to 80 mol% of the 2-hydroxyethyl acrylate constituting the (meth)acrylic acid ester polymer was reacted to obtain a (meth)acrylic acid ester polymer (active energy ray curable polymer) in which active energy ray curable groups were introduced into the side chains. The weight-average molecular weight of this active energy ray curable polymer was measured by the method described later and was found to be 600,000.

[0092] The above-mentioned active energy ray-curable polymer (100 parts by mass, on a solid content basis, the same applies hereafter) was mixed with 0.6 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyo Chem Co., Ltd., product name "BHS8515") as a crosslinking agent and 3 parts by mass of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, product name "Irgacure 184") in a solvent to obtain a coating solution of an adhesive composition with a solid content concentration of 20%.

[0093] The adhesive composition solution obtained as described above was applied to the release surface of the release sheet prepared in step 3 above, and the resulting coating film was dried by heating. This resulted in a laminate in which the 5 μm thick adhesive layer formed by the dried coating film and the release sheet were laminated together.

[0094] By bonding one side of an ethylene-methacrylic acid copolymer (EMAA) sheet (thickness: 80 μm) as a base material to the adhesive layer side of the laminate, a workpiece processing sheet was obtained in which the release surface of the release sheet prepared in step 3 above was laminated onto the adhesive surface of the adhesive sheet consisting of the base material and the adhesive layer.

[0095] 5. Measurement of weight-average molecular weight The weight-average molecular weight (Mw) mentioned above is the weight-average molecular weight on a standard polystyrene basis, measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> • Measuring device: Tosoh Corporation, HLC-8320 • GPC column (passes through in the following order): Manufactured by Tosoh Corporation TSK Gel Super H-H TSK gel superHM-H TSK Gel Super H2000 • Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0096] [Examples 2-4] A release sheet was prepared in the same manner as in Example 1, except that the ratio of kaolin to polyvinyl alcohol in the coating solution for forming the clay coat layer was changed as shown in Table 1, and the amount of the coating solution applied was also changed as shown in Table 1, and a sheet for workpiece processing was obtained.

[0097] [Comparative Example 1] A workpiece processing sheet was obtained in the same manner as in Example 1, except that a release agent layer was formed on one side of a 38 μm thick polyethylene terephthalate film in the same manner as in step 3 of Example 1, and the resulting release sheet was used.

[0098] [Comparative Example 2] Molten polyethylene was laminated to one side of the glassine paper obtained in the same manner as in Step 1 of Example 1, using a two-roll size press coater having an ultra-high smooth (ultra-mirror) roll surface. As a result, one side of the glassine paper was coated with 17.5 g / m². 2 A polyethylene laminate layer was formed. Furthermore, a release agent layer was formed on the polyethylene laminate layer in the same manner as in step 3 of Example 1. A workpiece processing sheet was obtained in the same manner as in Example 1, except that the release sheet obtained in this way was used.

[0099] [Test Example 1] (Calculation of carbon dioxide emissions) Based on the density of the glassine paper, PET film, PVA coating layer, clay coating layer, and polyethylene laminate layer used in the release sheets prepared in the examples and comparative examples, the density of these materials per 1 m 2 The weight per unit was calculated. Furthermore, based on the combustion reaction equations of these components, the amount of carbon dioxide emitted when these components are burned was calculated for each component. Then, for these emissions, the coefficients listed in the list of greenhouse gas emission factors published by the Ministry of the Environment were used to calculate the amount per cubic meter. 2 The amount of carbon dioxide emissions generated when the product is discarded was identified for each component. Furthermore, by obtaining the sum of the carbon dioxide emissions of the components that make up each release sheet, the total carbon dioxide emissions of the release sheet (g-CO2) were determined. 2e / m 2 The result was obtained. The results are shown in Table 1.

[0100] Although the release sheet has a release agent layer, the mass of the release agent layer is very small compared to other components, and the carbon dioxide emissions from the release agent layer are very small compared to other components. Therefore, carbon dioxide emissions from the release agent layer were not considered.

[0101] [Test Example 2] (Evaluation of Dicing Performance) Using a grinder (Disco Corporation, product name "DFG8540"), one side of a silicon wafer was ground to a thickness of 150 μm. The exposed adhesive layer, obtained by peeling the release sheet from the workpiece processing sheets manufactured in the examples and comparative examples, was then applied to the ground surface using a laminator.

[0102] Twenty minutes after application, the silicon wafer was diced into individual chips using a dicing device (DISCO Corporation, product name "DFD6362") under the following dicing conditions. The number of chip fragments that occurred after dicing was then counted. Dicing conditions Tip size: 2mm x 2mm Cutting height: 60 μm Blade rotation speed: 35,000 rpm Cutting speed: 50 mm / sec Blade: Manufactured by Disco, product name "NBC-2H 2050 27HECC"

[0103] The dicing performance was evaluated by comparing the number of chips that skipped against the following criteria. The results are shown in Table 1. ○: The number of chips that were dropped was 0. ×: The number of chips was one or more.

[0104] [Table 1]

[0105] As can be seen from Table 1, the workpiece processing sheets obtained in the examples significantly reduced the amount of carbon dioxide emitted when the release sheet was discarded compared to the comparative example using a resin-based release substrate. Furthermore, the workpiece processing sheets obtained in the examples exhibited good dicing performance. [Industrial applicability]

[0106] The workpiece processing sheet of the present invention can be suitably used for processing workpieces such as semiconductor wafers.

Claims

1. A release sheet comprising glassine paper, a clay coat layer laminated on one side of the glassine paper, and a release agent layer laminated on the side of the clay coat layer opposite to the glassine paper, A workpiece adhesive layer laminated on the side of the release agent layer opposite to the clay coat layer and A workpiece processing sheet equipped with, The aforementioned release sheet does not have a polyethylene laminate layer. A workpiece processing sheet characterized by the following features.

2. The workpiece processing sheet according to claim 1, characterized in that the clay coat layer contains kaolin.

3. The workpiece processing sheet according to claim 1, characterized in that the workpiece attachment layer is at least one of an adhesive layer, a bonding layer, and a protective film forming layer.

4. 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 expandable sheet, a die bond sheet, a back surface protection sheet, and a bump surface protection sheet.

5. A step of peeling off the release sheet from the workpiece processing sheet according to any one of claims 1 to 4 and attaching one or more workpieces to the exposed surface of the workpiece attachment layer that has been exposed, A step of separating at least one of the workpieces from the workpiece attachment layer and placing it on a predetermined object. A method for manufacturing a semiconductor device, characterized by comprising the above.

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