workpiece processing sheet

Abstract

This invention provides a workpiece machining sheet that exhibits excellent antistatic properties while effectively suppressing the generation of cutting discs. The workpiece machining sheet comprises: a substrate 11 and an adhesive layer 12 laminated on one side of the substrate 11. The substrate 11 includes: a surface layer 111 located relatively close to the adhesive layer 12, a back layer 113 located relatively far from the adhesive layer 12, and an intermediate layer 112 located between the surface layer 111 and the back layer 113. The surface layer 111 and the back layer 113 each contain an antistatic agent, and the thickness of the surface layer 111 is 10 μm or less.

Description

Technical Field

[0001] This invention relates to a workpiece processing wafer used in the processing of workpieces such as semiconductor wafers. Prior Technology

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

[0003] As a specific cutting technique, full cut dicing involves cutting the workpiece using a rotating circular cutter (cutting edge). In this process, to ensure the workpiece is completely cut from the workpiece sheet, typically not only the workpiece but also the adhesive layer is cut, and further, a portion of the substrate is also cut. At this time, a cutting disc, derived from the materials constituting the adhesive layer and the substrate, is generated from the workpiece sheet, and the wafer obtained by cutting the workpiece may be contaminated by the cutting disc. One typical form of this cutting disc is the presence of fine, filamentous cutting discs along the cutting line or near the cross-section of the wafer separated by the cut.

[0004] When a large number of these filamentous cutting blades adhere to the wafer, wire bonding is hindered. Furthermore, if wafer packaging is performed in this manner, the filamentous cutting blades attached to the wafer will decompose due to the heat of packaging. These thermal decomposition products will damage the package and become a cause of malfunction in the resulting device. Since these filamentous cutting blades are difficult to remove by cleaning, their presence significantly reduces the yield of the cutting step. Therefore, when using workpiece machining blades for cutting, it is necessary to prevent the formation of filamentous cutting blades.

[0005] Furthermore, when a workpiece processing sheet is peeled off from the substrate during a specific processing step, an electrostatic force known as stripping static electricity is generated between the workpiece processing sheet and the substrate. This electrostatic force can cause dust and other contaminants to adhere to the workpiece or device, and can also cause damage to the workpiece. Therefore, antistatic properties are also required for workpiece processing sheets.

[0006] Patent Document 1 discloses a substrate made by blending a specific antistatic agent, a specific polyolefin resin, and a specific rubber elastomer in a specific ratio, with the aim of providing a workpiece processing sheet with excellent cutting disc suppression effect and antistatic properties. [Previous Technical Documents] [Patent Literature]

[0007] Patent Document 1: Japanese Patent No. 5056112 Summary of the Invention

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

[0009] Incidentally, after the semiconductor wafer dicing process, the resulting wafers are generally cleaned. Specifically, a workpiece wafer carrying multiple wafers is fixed on a spinner table, where it is cleaned with ultrapure water and then dried (air-dried). After these processes are completed, the workpiece wafer carrying multiple wafers is pulled away from the spinner table. The inventors confirmed that static electricity is generated during this removal process.

[0010] If we also consider the above-mentioned static electricity removal process, conventional workpiece processing discs such as those in Patent Document 1 have not achieved a high level of cutting disc suppression effect and antistatic properties.

[0011] The present invention was made in view of these circumstances, and its object is to provide a workpiece machining sheet that exhibits excellent antistatic properties while effectively suppressing the generation of cutting discs. [Methods used to solve problems]

[0012] To achieve the above objectives, firstly, the present invention provides a workpiece processing sheet comprising: a substrate, and an adhesive layer laminated on one side of the substrate, characterized in that the substrate comprises: a surface layer located relatively close to the adhesive layer, a back layer located relatively far from the adhesive layer, and an intermediate layer located between the surface layer and the back layer, wherein the surface layer and the back layer each contain an antistatic agent, and the thickness of the surface layer is 10 μm or less (Invention 1).

[0013] The workpiece processing sheet related to the above invention (Invention 1) has a substrate having the above three layers, and the surface layer and the back layer each contain an antistatic agent. Furthermore, the thickness of the surface layer is within the above range, which provides excellent antistatic properties and effectively suppresses the generation of cutting discs.

[0014] In the above invention (Invention 1), it is preferable that the surface resistivity of the adhesive layer on the side opposite to the substrate is 1.0×10 13Ω / □ or less (Invention 2).

[0015] In the above inventions (Inventions 1 and 2), it is preferable that the intermediate layer does not contain the antistatic agent, or that the intermediate layer contains the antistatic agent in a smaller amount (unit: mass%) than the surface layer and the back layer respectively (Invention 3).

[0016] In the above inventions (Inventions 1 to 3), the antistatic agent is preferably a polymeric antistatic agent (Invention 4).

[0017] In the above inventions (Inventions 1 to 4), the thickness of the intermediate layer is preferably 40 μm or more and 75 μm or less (Invention 5).

[0018] In the above invention (Invention 1), the thickness of the back layer is preferably 2 μm or more and 40 μm or less (Invention 6).

[0019] Of the above inventions (Inventions 1 to 6), the cutting blade is preferred (Invention 7). [Invention Benefits]

[0020] The workpiece processing sheet related to this invention exhibits excellent antistatic properties and effectively suppresses the generation of cutting discs. Simple Explanation of the Diagram

[0021] [Figure 1] is a cross-sectional view of a workpiece processing sheet related to an embodiment of the present invention. Implementation

[0022] [The form in which the invention is carried out]

[0023] The following describes embodiments of the present invention. Figure 1 shows a cross-sectional view of a workpiece processing sheet according to an embodiment. The workpiece processing sheet 1 shown in Figure 1 includes: a substrate 11, and an adhesive layer 12 deposited on one side of the substrate 11.

[0024] As shown in FIG1, the substrate 11 comprises: a surface layer 111 located relatively close to the adhesive layer 12, a back layer 113 located relatively far from the adhesive layer 12, and an intermediate layer 112 located between the surface layer 111 and the back layer 113.

[0025] Then, both the surface layer 111 and the back layer 113 contain an antistatic agent. Thus, the workpiece processing sheet 1 of this embodiment has excellent antistatic properties. Therefore, static electricity during the separation of the stripping sheet and the workpiece from the workpiece processing sheet 1 can be effectively suppressed. Furthermore, after cleaning and drying the workpiece on the workpiece processing sheet 1, static electricity during the pulling of the workpiece processing sheet 1 from the cleaning tray is also effectively prevented.

[0026] Furthermore, the thickness of the surface layer 111 in this embodiment is 10 μm or less. As a result, by having a surface layer 111 located relatively close to the adhesive layer 12 with a thickness of 10 μm or less, the generation of cutting flakes can be effectively suppressed when cutting with the workpiece processing sheet related to this embodiment. The inventors have found that layers containing antistatic agents are more prone to generating cutting flakes than layers without antistatic agents. The workpiece processing sheet 1 related to this embodiment, by having a surface layer 111 containing an antistatic agent with a thickness of 10 μm or less, can effectively suppress the generation of cutting flakes while achieving the desired antistatic properties.

[0027] From the viewpoint of more effectively suppressing the occurrence of cutting particles, the thickness of the surface layer 111 is preferably 8 μm or less, and particularly preferably 4 μm or less. Furthermore, from the viewpoint of easily achieving better antistatic properties, the thickness of the surface layer 111 is preferably 1 μm or more, and particularly preferably 2 μm or more.

[0028] 1. Composition of workpiece machining discs (1) Substrate The substrate 11 in this embodiment, as described above, includes a surface layer 111, an intermediate layer 112, and a back layer 113. There are no particular limitations regarding the composition of these layers, as long as the surface layer 111 and the back layer 113 each contain an antistatic agent.

[0029] While the intermediate layer 112 may contain an antistatic agent, from the viewpoint of easily suppressing the generation of cutting fragments, it is preferable that the intermediate layer 112 does not contain an antistatic agent, or that the intermediate layer 112 contains an antistatic agent in a smaller amount (in mass%) than both the surface layer 111 and the back layer 113. In this way, by having an intermediate layer 112 without an antistatic agent, or with a smaller amount, existing between the surface layer 111 and the back layer 113, the generation of cutting fragments from the intermediate layer 112 can be effectively suppressed when the cutting edge reaches the intermediate layer 112 during cutting.

[0030] Other than the antistatic agent, any material capable of forming such layers in the various layers of the substrate 11 is not particularly limited; for example, a resin may be used. From the viewpoint of easily suppressing the generation of cutting fragments, it is preferable to use at least one of a polyolefin resin and a thermoplastic elastomer.

[0031] Furthermore, the surface layer and the back layer can have different compositions or they can have completely identical compositions.

[0032] (1-1) Antistatic agent The antistatic agent used in this embodiment is not particularly limited and can be any known agent. Examples of antistatic agents include low-molecular-weight antistatic agents and high-molecular-weight antistatic agents. However, from the viewpoint that it is easier to suppress the occurrence of cutting discs, or that it is difficult for bleed-out from the surface layer 111 and the back layer 113 to occur, high-molecular-weight antistatic agents are preferred.

[0033] Examples of polymeric antistatic agents include polyether ester amides, polyether polyolefin block copolymers, and copolymers containing polyether units. These copolymers may also contain metal salts such as alkali metal salts and alkaline earth metal salts, as well as ionic liquids.

[0034] The content of the antistatic agent in the surface layer 111 is preferably 3% by mass or more, particularly 5% by mass or more, and further preferably 10% by mass or more. By having an antistatic agent content of 3% by mass or more, it becomes easier to achieve good antistatic properties. Furthermore, the content of the antistatic agent in the surface layer 111 is preferably 40% by mass or less, particularly 35% by mass or less, and further preferably 30% by mass or less. By having an antistatic agent content of 40% by mass or less, it becomes easier to suppress the generation of cutting discs.

[0035] The content of the antistatic agent in the back layer 113 is preferably 10% by mass or more, particularly 20% by mass or more, and further preferably 30% by mass or more. By having an antistatic agent content of 10% by mass or more, it becomes easier to achieve good antistatic properties. Furthermore, the content of the antistatic agent in the back layer 113 is preferably 50% by mass or less, particularly 45% by mass or less, and further preferably 40% by mass or less. By having an antistatic agent content of 50% by mass or less, it becomes easier to control the occurrence of cutting discs.

[0036] Furthermore, as described above, it is preferable that the intermediate layer 112 does not contain an antistatic agent, or that the intermediate layer 112 contains an antistatic agent in a smaller amount (in mass%) than both the surface layer 111 and the back layer 113. When the intermediate layer 112 contains an antistatic agent, its content in the intermediate layer 112 is preferably 10% by mass or less, particularly 5% by mass or less, and further preferably 3% by mass or less. By having an antistatic agent content of 5% by mass or less in the intermediate layer 112, it becomes easier to suppress the occurrence of cutting discs. Moreover, as a lower limit value for the above-mentioned content, it can be, for example, 0.01% by mass or more.

[0037] (1-2) Polyolefin resins The specific examples of the polyolefin resins mentioned above are not particularly limited. Furthermore, in this specification, the term "polyolefin resin" refers to a polymer or copolymer that uses olefins as monomers, or a copolymer that uses olefins and molecules other than olefins as monomers, wherein the mass percentage of the olefin-based portion in the polymerized resin is 1.0% by mass or more.

[0038] The polymer constituting the above-mentioned polyolefin resin can be linear or have side chains. Furthermore, the polymer may also have aromatic rings or aliphatic rings.

[0039] Examples of olefin monomers constituting polyolefin resins include olefin monomers with 2 to 8 carbon atoms, α-olefin monomers with 3 to 18 carbon atoms, and olefin monomers with cyclic structures. Examples of olefin monomers with 2 to 8 carbon atoms include ethylene, propylene, 2-butene, and octene. Examples of α-olefin monomers with 3 to 18 carbon atoms include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, and 1-octadecene. Examples of olefin monomers with cyclic structures include norcamphene, cyclopentadiene, cyclohexadiene, dicyclopentadiene, and tetracyclododecene, as well as their derivatives.

[0040] Polyolefin resins can be used alone or in combination of two or more.

[0041] Among the specific examples of the above-mentioned polyolefin resins, it is preferable to use at least one of polyethylene containing ethylene as the main polymerization unit and polypropylene containing propylene as the main polymerization unit.

[0042] As for the aforementioned polypropylene, homopolymer polypropylene, random polypropylene, and block polypropylene are preferred, for example. These can be used individually or in mixtures of two or more. In particular, a mixture of homopolymer polypropylene and random polypropylene is preferred.

[0043] As for the aforementioned homopolymer polypropylene, random polypropylene, and block polypropylene, commercially available products can be used. Examples of commercially available homopolymer polypropylene include those manufactured by Prime Polymer Co., Ltd., under the trade names "Prime Polypro E111G," "Prime Polypro E-100GV," "Prime Polypro E-100GPL," and "Prime Polypro E-200GP." Examples of commercially available random polypropylene include those manufactured by Prime Polymer Co., Ltd., under the trade names "Prime Polypro B221WA," "Prime Polypro B241," "Prime Polypro E222," and "Prime Polypro E-333GV." Examples of commercially available block polypropylene products include those manufactured by Prime Polymer Co., Ltd., under the trade names "Prime Polypro E701G", "Prime Polypro E702G", and "Prime Polypro E702MG".

[0044] The polyethylene described above can be any of high-density polyethylene, medium-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, and linear low-density polyethylene, or a mixture of two or more of these.

[0045] In particular, low-density polyethylene is preferred as the polyethylene mentioned above. Examples of commercially available products include "Novatec LL" manufactured by Mitsubishi Chemical Corporation, the NEO-ZEX series manufactured by Prime Polymer Co., Ltd., and the ULTZEX series.

[0046] When any of the layers constituting the substrate 11 contains a polyolefin resin, the content of the polyolefin resin in that layer is preferably 10% by mass or more, particularly 15% by mass or more, and further preferably 20% by mass or more. Furthermore, the above content is preferably 100% by mass or less, particularly 95% by mass or less, and further preferably 90% by mass or less. By having the content of the polyolefin resin within the above range, the workpiece machining sheet 1 related to this embodiment can more easily obtain a better cutting edge suppression effect.

[0047] (1-3) Thermoplastic elastomers The thermoplastic elastomer described above can be any material other than the polyolefin resins mentioned above, as long as it can form the substrate 11, there are no particular limitations. Examples of thermoplastic elastomers include, for instance, olefin elastomers, rubber elastomers, urethane elastomers, styrene elastomers, acrylic elastomers, and vinyl chloride elastomers. These can be used alone or in combination of two or more.

[0048] Among the aforementioned elastomers, olefin-based elastomers are preferred from the viewpoint of easily obtaining good cutting edge suppression effects. Furthermore, in this specification, "olefin-based elastomer" refers to a copolymer containing building units derived from olefins or their derivatives (olefin compounds), which exhibits rubber-like elasticity in a temperature range including room temperature, while also possessing thermoplasticity.

[0049] Examples of olefin-based elastomers include resins comprising at least one type selected from the group consisting of ethylene-propylene copolymers, ethylene-α-olefin copolymers, propylene-α-olefin copolymers, butene-α-olefin copolymers, ethylene-propylene-α-olefin copolymers, ethylene-butene-α-olefin copolymers, propylene-butene-α-olefin copolymers, and ethylene-propylene-butene-α-olefin copolymers. Among these, ethylene-propylene copolymers are preferred.

[0050] When any of the layers constituting the substrate 11 contains a thermoplastic elastomer, the content of the thermoplastic elastomer in that layer is preferably 1% by mass or more, particularly 10% by mass or more, and further preferably 15% by mass or more. Furthermore, the above content is preferably 90% by mass or less, particularly 80% by mass or less, and further preferably 70% by mass or less. By having the content of the thermoplastic elastomer within the above range, the workpiece machining sheet 1 related to this embodiment can more easily obtain a better cutting edge suppression effect.

[0051] Furthermore, while the layers constituting the substrate 11 may contain styrene-based elastomers as thermoplastic elastomers, from the viewpoint of easily obtaining better cutting edge suppression effects, their content should be as low as possible. In particular, it is preferable that the layers constituting the substrate 11 do not contain styrene-based elastomers. Moreover, in this specification, "styrene-based elastomer" refers to a copolymer containing building units derived from styrene or its derivatives (styrene compounds), which has rubber-like elasticity and thermoplasticity in a region including room temperature.

[0052] When the layer constituting the substrate 11 contains a styrene-based elastomer, its content is preferably less than 10% by mass, particularly preferably less than 5% by mass, and further preferably less than 1% by mass. Moreover, the aforementioned situation of substantially not containing a styrene-based elastomer specifically refers to the styrene-based elastomer content in the layer constituting the substrate 11 being less than 0.2% by mass.

[0053] (1-4) Other components The layers constituting the substrate 11 may also contain other components besides the aforementioned antistatic agent, polyolefin resin, and thermoplastic elastomer. In particular, the resin composition may also contain components that are commonly used in the substrates of workpiece processing sheets.

[0054] Examples of such ingredients include various additives such as flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers. While there are no particular limitations on the content of these additives, it is preferable to maintain a level within which the base material can perform its desired function.

[0055] (1-5) Surface treatment of substrate On the surface of the substrate 11 where the adhesive layer 12 is deposited, surface treatments such as primer treatment, corona treatment, plasma treatment, and roughening treatment (passivation treatment) can be performed to improve adhesion to the adhesive layer 12. Examples of roughening treatments include embossing and sandblasting. Among these, corona treatment is preferred.

[0056] (1-6) Preparation of substrate The manufacturing method of the substrate 11 in this embodiment is not particularly limited. For example, melt extrusion methods such as T-die method and circular die method can be used; calendering method; solution method such as dry method and wet method can be used. Among these, melt extrusion method is preferred from the viewpoint of manufacturing substrate efficiently, and T-die method is particularly preferred.

[0057] Furthermore, when the substrate 11 is manufactured by melt extrusion, the components constituting each layer are separately mixed, and the resulting mixture is directly or made into temporary granules. Multiple layers are extruded simultaneously using a conventional extruder to form a film.

[0058] (1-7) Physical properties of the substrate, etc. The surface resistivity of the surface layer 111 side of the substrate 11 is preferably 1.0 × 10¹³ Ω / □ or less, particularly 1.0 × 10¹² Ω / □ or less, and even more preferably 1.0 × 10¹¹ Ω / □ or less. With a surface resistivity of 1.0 × 10¹³ Ω / □ or less, the workpiece processing sheet 1 related to this embodiment easily acquires good antistatic properties. Furthermore, the lower limit of the surface resistivity is not particularly limited; for example, it can be 1.0 × 10⁸ Ω / □ or more, particularly 1.0 × 10⁹ Ω / □ or more. Details of the method for measuring the surface resistivity are described in the following test examples.

[0059] In this embodiment, the thickness of the intermediate layer 112 is preferably 40 μm or more, particularly 50 μm or more, and further preferably 60 μm or more. With an intermediate layer 112 thickness of 40 μm or more, it becomes easier to suppress the generation of cutting edges. Furthermore, the workpiece machining sheet 1 readily possesses appropriate strength, making it easier to effectively support the workpiece fixed to the workpiece machining sheet 1. The thickness of the intermediate layer 112 is preferably 100 μm or less, particularly 90 μm or less, and further preferably 80 μm or less. With an intermediate layer 112 thickness of 100 μm or less, the workpiece machining sheet 1 exhibits good flexibility, for example, it becomes easier to stretch effectively.

[0060] In this embodiment, the thickness of the back layer 113 is preferably 2 μm or more, particularly 4 μm or more, and further preferably 8 μm or more. With a back layer 113 thickness of 2 μm or more, the workpiece processing sheet 1 easily acquires good antistatic properties. Furthermore, the thickness of the back layer 113 is preferably 40 μm or less, particularly 30 μm or less, and further preferably 25 μm or less. With a back layer 112 thickness of 40 μm or less, the workpiece processing sheet 1 acquires good flexibility, for example, it becomes easier to stretch effectively.

[0061] (2) Adhesive layer As for the adhesive constituting the adhesive layer 12 in this embodiment, there are no particular limitations as long as it can exert sufficient adhesion to the adhered object (in particular, adhesion to the workpiece sufficient for machining the workpiece). Examples of adhesives constituting the adhesive layer 12 include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives. Among these, acrylic adhesives are preferred from the viewpoint of easily exerting the desired adhesion.

[0062] The adhesive constituting the adhesive layer 12 in this embodiment may be an adhesive without active energy line curing properties, but it is preferable to use an adhesive with active energy line curing properties (hereinafter, sometimes referred to as "active energy line curing adhesive"). Because the adhesive layer 12 is composed of an active energy line curing adhesive, the adhesive layer 12 is hardened by irradiation with active energy lines, which easily reduces the adhesion of the workpiece processing sheet 1 to the adhered object. In particular, by irradiation with active energy lines, it becomes easier to separate the processed workpiece from the workpiece processing sheet 1.

[0063] The active energy line curable adhesive constituting the adhesive layer 12 can be a polymer with active energy line curability as the main component, or a mixture of an active energy line non-curable polymer (a polymer without active energy line curability) and monomers and / or oligomers having at least one active energy line curable group as the main component. Alternatively, the active energy line curable adhesive can also be a mixture of a polymer with active energy line curability and monomers and / or oligomers having at least one active energy line curable group.

[0064] The aforementioned polymers with active energy line hardening properties are preferably (meth)acrylate polymers (hereinafter, sometimes referred to as "active energy line hardening polymers") with active energy line hardening functional groups (active energy line hardening groups) introduced into their side chains. These active energy line hardening polymers are preferably obtained by reacting an acrylic polymer having a monomer unit containing a functional group with a compound containing an unsaturated group having the functional group bonded to that functional group. Furthermore, in this specification, (meth)acrylic acid refers to both acrylic acid and methacrylic acid. Other similar terms are also used in the same way. Moreover, "polymer" also includes the concept of "copolymer".

[0065] The aforementioned acrylic polymers having functionalized monomer units can also be monomers containing functional groups, polymerized with other monomers. As such functionalized monomers and other monomers, the aforementioned unsaturated compounds can also be used, for example, those disclosed in International Publication No. 2018 / 084021.

[0066] The weight-average molecular weight of the aforementioned active energy line-curable polymer is preferably 10,000 or higher, particularly 150,000 or higher, and even more preferably 200,000 or higher. Furthermore, the weight-average molecular weight is preferably 1.5 million or lower, particularly 1 million or lower. Moreover, the weight-average molecular weight (Mw) in this specification is a converted value for standard polystyrene determined by gel permeation chromatography (GPC).

[0067] As a component of the non-hardening polymer of the above-mentioned active energy line, for example, the above-mentioned acrylic polymer containing unsaturated group compounds can be used before the reaction.

[0068] The weight-average molecular weight of the acrylic polymer used as the non-hardening polymer component of the aforementioned active energy line is preferably 10,000 or more, particularly 150,000 or more, and even more preferably 200,000 or more. Furthermore, the weight-average molecular weight is preferably 1.5 million or less, particularly 1 million or less.

[0069] Furthermore, as monomers and / or oligomers having at least one or more active energy line hardening groups, polyols and esters of (meth)acrylic acid can be used, for example.

[0070] Furthermore, when using ultraviolet light as the active energy line to harden the active energy line adhesive, it is preferable to add a photopolymerization initiator to the adhesive. In addition, non-hardening polymer or oligomer components of the active energy line, crosslinking agents, etc., may also be added to the adhesive.

[0071] In this embodiment, the thickness of the adhesive layer 12 is preferably 1 μm or more, particularly 3 μm or more, and further preferably 5 μm or more. Furthermore, the thickness of the adhesive layer 12 is preferably 70 μm or less, particularly 30 μm or less, and further preferably 15 μm or less. With the thickness of the adhesive layer 12 within the above-mentioned range, the workpiece processing sheet 1 related to this embodiment easily achieves the desired adhesion.

[0072] (3) Peeling sheet The workpiece processing sheet 1 related to this embodiment can also be peeled off on the area layer for the purpose of protecting the surface (hereinafter sometimes referred to as the "adhesive surface") opposite to the substrate 11 in the adhesive layer 12 until it is attached to the workpiece.

[0073] The composition of the aforementioned release liner is arbitrary; for example, it involves peeling a plastic film using a release agent. Specific examples of such plastic films include polyester films made of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, as well as polyolefin films made of polypropylene and polyethylene. As the release agent, silicone-based, fluorine-based, and long-chain alkyl-based agents can be used; among these, silicone-based agents, which are inexpensive and offer stable performance, are preferred.

[0074] There are no particular limitations on the thickness of the aforementioned release sheet; for example, it can be above 16 μm and below 250 μm.

[0075] (4) Other The workpiece processing sheet 1 of this embodiment can also have an area layer adhesive layer on the opposite side of the substrate 11 in the adhesive layer 12. In this case, the workpiece processing sheet 1 of this embodiment can be used as a cutting and die bonding sheet. By attaching the workpiece to the side of the adhesive layer opposite to the adhesive layer 12 in the adhesive layer, and cutting the workpiece together with the adhesive layer, a wafer with an adhesive layer laminated in individual wafer form can be obtained. The wafer becomes easier to fix to the object on which the wafer is mounted by the individual wafer adhesive layer. As for the material constituting the adhesive layer, it is preferable to use a material containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, or a material containing a B-stage (semi-cured) thermosetting adhesive component.

[0076] Furthermore, the workpiece processing sheet 1 of this embodiment can also form a protective film layer on the adhesive area of ​​the adhesive layer 12. In this case, the workpiece processing sheet 1 of this embodiment can be used as a protective film forming and cutting sheet. By attaching a workpiece to the surface opposite to the adhesive layer 12 in the protective film forming layer and cutting the workpiece together with the protective film forming layer, a wafer with a laminated protective film forming layer can be obtained. It is preferable to use a workpiece with a circuit formed on one side. In this case, the protective film forming layer is usually laminated on the surface opposite to the surface with the circuit formed. By curing the laminated protective film forming layer at a specific time, a protective film with sufficient durability can be formed on the wafer. It is preferable that the protective film forming layer is formed by an uncured curable adhesive.

[0077] 2. Physical properties of workpiece machining sheets In this embodiment, the surface resistivity of the adhesive layer 12, on the side opposite to the substrate 11 (adhesive surface), of the workpiece processing sheet 1 before ultraviolet irradiation is preferably 1.0 × 10¹³ Ω / □ or less, particularly 1.0 × 10¹² Ω / □ or less, and even more preferably 1.0 × 10¹¹ Ω / □ or less. By achieving a surface resistivity of 1.0 × 10¹³ Ω / □ or less, the workpiece processing sheet 1 of this embodiment readily possesses good antistatic properties. Furthermore, the lower limit of the surface resistivity is not particularly limited; for example, it can be 1.0 × 10⁸ Ω / □ or more, particularly 1.0 × 10⁹ Ω / □ or more. Details of the method for measuring the surface resistivity are described in the following experimental examples.

[0078] 3. Manufacturing method of workpiece machining sheet The manufacturing method of the workpiece processing sheet 1 related to this embodiment is not particularly limited. For example, it is preferable that the workpiece processing sheet 1 can be obtained by forming an adhesive layer 12 on a release sheet, and then using one side of the area layer substrate 11 on the opposite side of the release sheet in the adhesive layer 12.

[0079] The adhesive layer 12 described above can be formed by known methods. For example, an adhesive composition for forming the adhesive layer 12 can be prepared, and a coating liquid further containing a solvent or dispersant as needed. Then, the coating liquid is applied to the peelable side of the release sheet (hereinafter, sometimes referred to as the "peel surface"). Next, the adhesive layer 12 can be formed by drying the resulting coating film.

[0080] The coating of the aforementioned coating liquid can be carried out by known methods, such as bar coating, blade coating, roller coating, flap coating, die coating, gravure coating, etc. Furthermore, as long as the coating liquid is suitable for coating, its characteristics are not particularly limited. The components used to form the adhesive layer 12 are sometimes contained as a solute and sometimes as a dispersed phase. In addition, the release liner can also be used as a process material for release, and can also protect the adhesive layer 12 during the period until it is adhered to the substrate.

[0081] When the adhesive composition used to form the adhesive layer 12 contains the aforementioned crosslinking agent, it is preferable to change the aforementioned drying conditions (temperature, time, etc.) or to additionally perform a heat treatment to allow the polymer components in the coating film to undergo a crosslinking reaction with the crosslinking agent, thereby forming a crosslinked structure within the adhesive layer 12 at a desired density. Furthermore, in order to ensure that the aforementioned crosslinking reaction proceeds sufficiently, after the adhesive layer 12 is bonded to the substrate 11, for example, it can be left to stand for several days in an environment of 23°C and 50% relative humidity for a so-called curing process.

[0082] 4. How to use the workpiece machining disc The workpiece processing sheet 1 of this embodiment can be used for processing workpieces such as semiconductor wafers. In other words, after the adhesive surface of the workpiece processing sheet 1 of this embodiment is attached to the workpiece, workpiece processing can be performed on the workpiece processing sheet 1. For this processing, the workpiece processing sheet 1 of this embodiment can be used as a back-grinding sheet, a dicing sheet, a stretching sheet, a wafer picking sheet, etc. Here, examples of workpieces include semiconductor wafers, semiconductor components such as semiconductor packages, and glass components such as glass plates.

[0083] The workpiece machining disc 1 of this embodiment, as described above, effectively suppresses the generation of cutting discs, especially fine filamentous cutting discs, when used in cutting with a rotating round blade. Therefore, the workpiece machining disc 1 of this embodiment is particularly suitable as a cutting disc among the aforementioned workpiece machining discs.

[0084] Furthermore, the workpiece processing sheet 1 of this embodiment, as described above, possesses excellent antistatic properties. The workpiece processing sheet 1 of this embodiment can suppress static electricity during workpiece separation when separating the release sheet. Furthermore, the workpiece processing sheet 1 of this embodiment can effectively suppress static electricity when pulling the workpiece processing sheet away from the cleaning tray after cleaning and drying the wafer in a fixed state. Therefore, the workpiece processing sheet 1 of this embodiment is also suitable for use in such cleaning and drying processes.

[0085] Furthermore, when the workpiece processing sheet 1 of this embodiment has the aforementioned adhesive layer, the workpiece processing sheet 1 can be used as a cutting and grain bonding sheet. Moreover, when the workpiece processing sheet 1 of this embodiment has the aforementioned protective film forming layer, the workpiece processing sheet 1 can be used as a protective film forming and cutting sheet.

[0086] Furthermore, when the adhesive layer 12 in the workpiece processing sheet 1 of this embodiment is composed of the aforementioned active energy line hardening adhesive, it is preferable to irradiate it with an active energy line at the time of use. In other words, when processing a workpiece on the workpiece processing sheet 1 and separating the processed workpiece from the workpiece processing sheet 1, it is preferable to irradiate the adhesive layer 12 with an active energy line before separation. In this way, the adhesive layer 12 hardens, the adhesion of the adhesive sheet to the processed workpiece is effectively reduced, and the separation of the processed workpiece becomes easier.

[0087] The embodiments described above are for the purpose of understanding the present invention and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments are intended to include all design changes and equivalents to which the present invention falls.

[0088] For example, other layers may be deposited between the substrate 11 and the adhesive layer 12 in the workpiece processing sheet 1 related to this embodiment, or on the side of the substrate 11 opposite to the adhesive layer 12. Furthermore, other layers may also be deposited on the side of the surface layer 111 opposite to the intermediate layer 112, between the surface layer 111 and the intermediate layer 112, between the intermediate layer 112 and the back layer 113, and on the side of the back layer 113 opposite to the intermediate layer 112. [Example]

[0089] The present invention will be further described in detail below by way of examples, etc., but the scope of the present invention is not limited to these examples.

[0090] [Example 1] (1) Fabrication of the substrate 36 parts by weight of random polypropylene resin (manufactured by Japan Polypropylene Corporation, trade name "Novatec FX3B"), 59 parts by weight of olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, trade name "WELNEX RFX4V"), and 5 parts by weight of antistatic agent (manufactured by Sanyo Chemical Co., Ltd., trade name "PELECTRON PVL") were dried separately and then chained together using a biaxial chain mixer to obtain granules for the surface layer and the back layer.

[0091] In addition, 38 parts by weight of random polypropylene resin (manufactured by Japan Polypropylene Corporation, trade name "Novatec FX3B") and 62 parts by weight of olefin-based thermoplastic elastomer (manufactured by Japan Polypropylene Corporation, trade name "WELNEX RFX4V") were dried separately and then mixed by a biaxial mixer to obtain intermediate layer granules.

[0092] Using the two types of granules obtained as described above, a substrate with a three-layer structure was obtained by co-extrusion molding using a small T-die extruder (manufactured by Toyo Seiki Co., Ltd., trade name "LABO PLASTOMILL"). This substrate consisted of a 4μm thick surface layer, a 72μm thick intermediate layer, and a 4μm thick back layer.

[0093] (2) Preparation of adhesive composition 62 parts by mass of n-butyl acrylate, 10 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate were polymerized by solution polymerization to obtain a (meth)acrylate polymer. Next, methacryloyloxyethyl isocyanate (MOI) was added in an amount equivalent to 80 moles of 2-hydroxyethyl acrylate constituting the above (meth)acrylate polymer, while dibutyltin dilaurate (DBTDL), acting as a tin-containing catalyst, was added in an amount of 0.13 parts by mass relative to 100 parts by mass of the above (meth)acrylate polymer. Subsequently, the reaction was carried out at 50°C for 24 hours to obtain a (meth)acrylate polymer with active energy line-curing groups introduced into the side chains. The weight average molecular weight of this active energy line-curing polymer was determined by the following method and was 500,000.

[0094] 100 parts by weight (converted to solids, the same below) of the (meth)acrylate polymer with active energy line hardening groups introduced into the side chain obtained above, 2 parts by weight of 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionic)-phenylmethyl]phenyl}-2-methyl-propane-1-one (manufactured by BASF, trade name "Omnirad 127") as a photopolymerization initiator, and 1 part by weight of trimethylolpropane-modified methylphenyl diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate L") as a crosslinking agent are mixed in a solvent to obtain a coating liquid of adhesive composition.

[0095] (3) Formation of adhesive layer For the release surface of a release sheet (manufactured by LINTEC Corporation, trade name "SP-PET381031") formed by a silicone-based release agent layer on one side of a polyethylene terephthalate film with a thickness of 38 μm, a coating liquid of the adhesive composition obtained in step (2) above is applied, and the film is dried by heating to obtain a laminate formed by an adhesive layer with a thickness of 5 μm on the release sheet.

[0096] (4) Fabrication of adhesive sheet After corona treatment is performed on the surface layer side of the substrate obtained in step (1), the corona-treated surface is bonded to the adhesive layer side of the laminate obtained in step (3) to obtain a workpiece processing sheet.

[0097] Here, the above weight-average molecular weight (Mw) is the converted standard polystyrene weight-average molecular weight determined using gel permeation chromatography (GPC) under the following conditions (GPC determination). <Measurement Conditions> Measuring apparatus: Tosoh Corporation, HLC-8320 GPC tubing (in the following order): Manufactured by Tosoh Corporation TSK gel super HH TSK gel super HM-H TSK gel super H2000 Determination solvent: tetrahydrofuran Measurement temperature: 40℃

[0098] [Examples 2-6, Comparative Examples 1-2] Except for the changes to the composition of the ingots used to form the substrate and the thickness of each layer as described in Table 1, the workpiece processing sheet was obtained in the same manner as in Example 1.

[0099] [Experimental Example 1] (Measurement of Surface Resistivity) The surface resistivity of the substrates manufactured in the examples and comparative examples was measured using a digital electroderter (manufactured by Advanest) at 23°C and 50% relative humidity for 24 hours after humidity control. The results are shown in Table 2.

[0100] Furthermore, the workpiece processing sheet manufactured in the examples and comparative examples was cut into 100mm × 100mm pieces and used as a sample for surface resistivity measurement. This sample for surface resistivity measurement was subjected to humidity control at 23°C and 50% relative humidity for 24 hours. The release sheet was then peeled off, and the surface resistivity of the exposed adhesive layer side (adhesive surface) was measured in the same manner as described above. These results are also shown in Table 2.

[0101] [Experimental Example 2] (Evaluation of the cutting disc suppression effect) After peeling off the release liner from the workpiece processing sheet manufactured in the examples and comparative examples, an adhesive layer is applied to one side of a 6-inch silicon wafer using a laminator (manufactured by LINTEC Corporation, trade name "RAD2500m / 12"). Next, a dicing ring frame is attached to the periphery of the exposed surface of the workpiece processing sheet (the area not overlapping with the silicon wafer). Then, the workpiece processing sheet is cut to the outer diameter of the ring frame.

[0102] Subsequently, the silicon wafer is individually chipped into 5mm x 5mm wafers by using a dicing device (manufactured by Disco Corporation, trade name "DFD6362") under the following dicing conditions. Cutting conditions Wafer thickness: 150μm Blade: Z1 and Z2 below are both manufactured by Disco Corporation. Z1: Product name "ZH05-SD3000-50DD" Z2: Product Name "NBC-SD3000-50BB" Blade rotation speed Z1: 55000rpm Z2: 45000rpm Cutting speed: 20 mm / sec Blade height Z1: 0.135mm Z2: 0.065mm Cutting water flow rate: 1.0L / min Cutting water temperature: 25℃

[0103] After dicing, the surface of the resulting wafer was observed using an electron microscope (KEYENCE, trade name "VHZ-100", magnification: 300x) to count the number of cut wafers. Specifically, the number of cut wafers present on each wafer along the dicing line was counted. Then, the wafer-cutting suppression effect was evaluated according to the following criteria. The number of cut wafers and the evaluation results are shown in Table 2. ◎: The number of cutting blades is 3 or less. ○: The number of cutting blades is more than 3 but less than 10. ×: The number of cutting blades exceeds 10.

[0104] [Experimental Example 3] (Evaluation of Antistatic Properties) Using a grinder (Disco Corporation, trade name "DFG8540"), one side of a 6-inch silicon wafer was ground until the thickness reached 350 μm. For this ground surface, a bonding machine was used to attach the exposed adhesive layer after the release sheet was peeled off using a workpiece processing sheet manufactured from the examples and comparative examples.

[0105] Twenty minutes after self-attachment, the silicon wafer is individually chipped into wafers by using a cutting device (manufactured by Disco Corporation, trade name "DFD6362") under the following cutting conditions. Cutting conditions Chip size: 10mm × 10mm Cutting height: 60μm Blade: Product name "ZH05-SD2000-Z1-90 CC" Blade rotation speed: 35000 rpm Cutting speed: 60 mm / sec Cutting water flow rate: 1.0L / min Cutting water temperature: 20℃

[0106] After cutting, the workpiece wafer is fixed in place by being adsorbed onto a cleaning tray, and then cleaned and dried as described above. Next, the electrostatic voltage (V) of the workpiece wafer is measured immediately after it is lifted from the cleaning tray using a measuring instrument (Prostat, trade name "PFK-100"). The antistatic properties are then evaluated according to the following criteria. The electrostatic voltage and evaluation results are shown in Table 2. ◎: Static voltage is below 100V. ○: Static voltage exceeding 100V is below 500V. ×: Static voltage exceeds 500V.

[0107] [Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Thickness of each layer (surface layer / intermediate layer / back layer) (μm) 4 / 72 / 4 4 / 64 / 12 8 / 60 / 12 4 / 64 / 12 4 / 64 / 12 4 / 64 / 12 12 / 56 / 12 4 / 72 / 4 composition (parts by weight) Surface layer polypropylene NOVATEC FX3B (Manufactured by Japan Polypropylene Corporation) 36 36 36 34 32 32 36 38 olefins Thermoplastic elastomers WELNEX RFX4V (Manufactured by Japan Polypropylene Corporation) 59 59 59 56 53 53 59 62 Antistatic agent PELECTRON PVL (Sanyo Chemical Co., Ltd.) 5 5 5 10 15 - - - Intermediate layer polypropylene NOVATEC FX3B (Manufactured by Japan Polypropylene Corporation) 38 38 38 38 38 38 38 38 olefins Thermoplastic elastomers WELNEX RFX4V (Manufactured by Japan Polypropylene Corporation) 62 62 62 62 62 62 62 62 Back layer polypropylene NOVATEC FX3B (Manufactured by Japan Polypropylene Corporation) 36 36 36 34 32 32 36 38 olefins Thermoplastic elastomers WELNEX RFX4V (Manufactured by Japan Polypropylene Corporation) 59 59 59 56 53 53 59 62 Antistatic agent PELECTRON PVL (Sanyo Chemical Co., Ltd.) 5 5 5 10 15 - - - PELECTRON PVH (Sanyo Chemical Co., Ltd.) - - - - - 15 5 -

[0108] [Table 2] Surface resistivity (Ω / □) Cutting disc suppression effect Antistatic properties substrate Surface side sticky dough Number of items evaluate Static voltage (V) evaluate Example 1 3.7 × 10 11 1.4 × 10 12 0 ◎ 258 ○ Example 2 4.4 × 10 11 5.2 × 10 11 3 ◎ 160 ○ Example 3 2.3 × 10 11 3.0 × 10 11 8 ○ 51 ◎ Example 4 9.6 × 10 10 1.8 × 10 11 1 ◎ 20 ◎ Example 5 4.5 × 10 10 7.3 × 10 10 4 ○ 18 ◎ Example 6 1.3 × 10 11 1.6 × 10 11 1 ◎ 17 ◎ Comparative Example 1 1.9 × 10 11 2.1 × 10 11 twenty three × 18 ◎ Comparative Example 2 >10 15 >10 15 0 ◎ >1000 ×

[0109] As can be clearly seen from Table 2, the workpiece machining sheet manufactured in the embodiment effectively suppresses cutting edges and also exhibits excellent antistatic properties. [Industrial Utilization]

[0110] The workpiece processing wafer of the present invention can be applied to the processing of workpieces such as semiconductor wafers.

[0111] 1: Workpiece machining sheet 11: Substrate 111: Surface layer 112: Intermediate layer 113: Backside layer 12: Adhesive layer

Claims

1. A workpiece processing sheet comprising a substrate and an adhesive layer deposited on one side of the substrate, characterized in that: the substrate comprises: a surface layer located relatively close to the adhesive layer, a back layer located relatively far from the adhesive layer, and an intermediate layer located between the surface layer and the back layer; the surface layer and the back layer are each composed of random polypropylene resin, olefin-based thermoplastic elastomer and antistatic agent, or composed of random polypropylene resin, olefin-based thermoplastic elastomer, antistatic agent and additives; the content of antistatic agent in the surface layer is 15% by mass or less, and the content of antistatic agent in the back layer is 15% by mass or less; the additives are selected from at least one of flame retardant, plasticizer, lubricant, antioxidant, colorant, infrared absorber, ultraviolet absorber and ion trap; the thickness of the surface layer is 10 μm or less; the intermediate layer does not contain the antistatic agent; and the workpiece processing sheet is a cutting sheet.

2. As in request item 1, the sheet for machining the workpiece, wherein, The surface resistivity of the side of the adhesive layer opposite to the substrate is less than 1.0 × 10¹³ Ω / □.

3. As in request item 1, the sheet for machining the workpiece, wherein, The above-mentioned antistatic agent is a polymeric antistatic agent.

4. As in request item 1, the sheet for machining the workpiece, wherein, The thickness of the aforementioned intermediate layer is greater than 40 μm and less than 75 μm.

5. As in request item 1, the sheet for machining the workpiece, wherein, The thickness of the aforementioned back layer is greater than 2μm and less than 40μm.

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