Sheet for workpiece processing

Abstract

To provide a workpiece processing sheet which is excellent in pick-up property and antistatic property while using an active energy ray non-curable adhesive for an adhesive layer.SOLUTION: In a workpiece processing sheet 1 including a base material 11 and an adhesive layer 12, the base material 11 includes a front surface layer 111 located to be proximal to the adhesive layer 12, a back surface layer 113 located to be distal to the adhesive layer, and an intermediate layer 112 located between the front surface layer 111 and the back surface layer 113. The adhesive layer 12 is made of an active energy ray non-curable adhesive, and the front surface layer 111 and the back surface layer 113 contain an antistatic agent. Tensile stresses at tensile elongations of 20% and 50% are 8 MPa or more and 30 MPa or less when a tensile test is performed on the base material 11 under an environment of a temperature of 23°C and a relative humidity of 50%RH.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a work processing sheet used for processing a work such as a semiconductor wafer.

Background Art

[0002] Semiconductor wafers such as silicon and gallium arsenide, and various packages are manufactured in a large-diameter state, cut (diced) into chips, peeled off (picked up), and then transferred to the next mounting process. At this time, a work such as a semiconductor wafer is laminated on an adhesive sheet having a base material and an adhesive layer (hereinafter sometimes referred to as a "work processing sheet"), and processing such as back grinding, dicing, cleaning, drying, expanding, picking up, and mounting is performed.

[0003] For example, a semiconductor wafer that has completed back grinding is attached to a sheet, and dicing is performed on the sheet. By dicing, the semiconductor wafer is separated into a plurality of semiconductor chips. Thereafter, the plurality of semiconductor chips are individually picked up from the sheet.

[0004] As another method, after the above dicing, the plurality of semiconductor chips supported on the sheet are transferred to another sheet, and the plurality of semiconductor chips are individually picked up from the other sheet.

[0005] The pickup of semiconductor chips from the sheet as described above is performed using a device such as a die ejector. This device individually pushes up the semiconductor chips from the surface opposite to the surface of the sheet to which the semiconductor chips are attached, and separates them from the other semiconductor chips. By pushing up one semiconductor chip in this way, it becomes easier to perform pickup by a collet. Also, at this time, if necessary, the sheet can be expanded to create a gap between the semiconductor chips, making it easier to push up and pick up.

[0006] As a pushing-up method, there is a method using one or more pins or needles. In this method, the tip of the pin or needle touches the sheet at a point, and the semiconductor chip is pushed up at the point. However, in recent years, as the semiconductor chip has become thinner and the use of harder and more brittle materials as semiconductor materials has advanced, the semiconductor chip has become more brittle. When handling such a semiconductor chip, if the pushing-up amount of the pin or needle is large, the semiconductor chip may be damaged.

[0007] On the other hand, as the adhesive for the adhesive layer in the above-mentioned work processing sheet, an ultraviolet curable adhesive is often used. In the case of an ultraviolet curable adhesive, the adhesive force can be reduced by irradiating the adhesive layer with ultraviolet rays to cure the adhesive before picking up the semiconductor chip. Therefore, the semiconductor chip can be easily picked up from the adhesive layer. However, from the viewpoint of the process or the type of semiconductor chip, there may be cases where it is desirable to use an ultraviolet non-curable adhesive rather than an ultraviolet curable adhesive. In this case, obtaining good pick-up properties is more difficult than when using an ultraviolet curable adhesive.

[0008] Patent Document 1 discloses a dicing film in which a base material contains a specific random polypropylene (A) and a specific olefin-based elastomer (B) in order to obtain excellent pick-up properties together with suitable expandability, and the 100% tensile stress of the olefin-based elastomer (B) is defined.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] Incidentally, the work processing sheet is peeled off from the adherend when a predetermined processing step is completed. At this time, static electricity called peeling electrification may be generated between the work processing sheet and the adherend. Such static electricity causes dust and the like to adhere to the work or the device, and also causes damage to the work and the like. Therefore, the work processing sheet is also required to have antistatic properties.

[0011] Also, after the dicing process of the semiconductor wafer, generally, the obtained chips may be washed. Specifically, the work processing sheet on which a plurality of chips are placed is adsorbed and fixed on a spinner table, and the chips are washed with ultrapure water and then dried (air-dried) on the work processing sheet. After these processes are completed, the work processing sheet on which a plurality of chips are placed is separated from the spinner table. However, the inventors have confirmed that peeling electrification also occurs during this separation.

[0012] However, the conventional work processing sheet such as that in Patent Document 1 does not correspond to antistatic properties, and the problem of peeling electrification as described above has occurred.

[0013] The present invention has been made in view of such a situation, and an object thereof is to provide a work processing sheet that is excellent in pick-up properties while using an active energy ray non-curable adhesive in the adhesive layer and is also excellent in antistatic properties.

Means for Solving the Problems

[0014] In order to achieve the above object, firstly, the present invention provides a sheet for workpiece processing, comprising a base material and an adhesive layer laminated on one side of the base material, wherein the base material includes a surface layer located proximal to the adhesive layer, a back surface layer located distal to the adhesive layer, and an intermediate layer located between the surface layer and the back surface layer; the adhesive layer is made of an active energy ray non-curable adhesive; the surface layer and the back surface layer contain an antistatic agent; and when a tensile test is performed on the base material in an environment of a temperature of 23 °C and a relative humidity of 50% RH, the tensile stress at a tensile elongation of 20% and 50% is 8 MPa or more and 30 MPa or less. (Invention 1)

[0015] In the above invention (Invention 1), since the surface layer and the back surface layer contain an antistatic agent, it has excellent antistatic properties. Further, since the surface layer contains an antistatic agent and the base material has the above tensile physical properties, even when an active energy ray non-curable adhesive is used for the adhesive layer, the pick-up property when picking up a chip from the sheet for workpiece processing is excellent.

[0016] In the above invention (Invention 1), it is preferable that the active energy ray non-curable adhesive is an acrylic adhesive. (Invention 2)

[0017] In the above inventions (Inventions 1 and 2), it is preferable that each of the surface layer, the intermediate layer, and the back surface layer contains at least one of a polyolefin resin and an olefinic thermoplastic elastomer. (Invention 3)

[0018] In the above inventions (Inventions 1 to 3), it is preferable that the intermediate layer does not contain an antistatic agent or contains an antistatic agent in a content (unit: mass%) less than that of each of the surface layer and the back surface layer. (Invention 4)

[0019] In the above inventions (Inventions 1 to 4), it is preferable that the antistatic agent is a polymer type antistatic agent. (Invention 5)

[0020] In the above inventions (Inventions 1 to 5), the surface resistivity of the surface of the adhesive layer on the side opposite to the base material is preferably 1.0×10 13 Ω / square or less (Invention 6).

[0021] In the above inventions (Inventions 1 to 6), it is preferably a dicing sheet (Invention 7).

Advantages of the Invention

[0022] The sheet for work processing according to the present invention is excellent in pick-up property while using an active energy ray non-curable adhesive in the adhesive layer, and is also excellent in antistatic property.

Brief Description of the Drawings

[0023]

Figure 1

Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present invention will be described. FIG. 1 shows a cross-sectional view of a sheet for work processing according to an embodiment of the present invention. The sheet for work processing 1 shown in FIG. 1 includes a base material 11 and an adhesive layer 12 laminated on one side of the base material 11.

[0025] As shown in FIG. 1, the base material 11 includes a surface layer 111 located proximal to the adhesive layer 12, a back surface layer 113 located distal to the adhesive layer 12, and an intermediate layer 112 located between the surface layer 111 and the back surface layer 113.

[0026] In the workpiece processing sheet 1 according to this embodiment, the adhesive layer 12 is made of an active energy ray non-curable adhesive, and the surface layer 111 and the back surface layer 113 contain an antistatic agent. When a tensile test is performed on the base material 11 in an environment of a temperature of 23°C and a relative humidity of 50%RH, the tensile stress at a tensile elongation of 20% and 50% is 8 MPa or more and 30 MPa or less. Hereinafter, the physical properties related to the tensile stress may be referred to as "tensile physical properties". The specific measurement method of the tensile test in this specification is as shown in the test example described later.

[0027] In the workpiece processing sheet 1 according to this embodiment, since the surface layer 111 and the back surface layer 113 contain an antistatic agent, it has excellent antistatic properties. Therefore, it is possible to favorably suppress the peeling charge when separating the release sheet or the workpiece from the workpiece processing sheet 1. Furthermore, after cleaning and drying the workpiece on the workpiece processing sheet 1, it is also possible to favorably prevent the peeling charge when separating the workpiece processing sheet 1 from the spinner table.

[0028] Also, in the workpiece processing sheet 1 according to this embodiment, since the surface layer 111 contains an antistatic agent and the base material 11 has the above-described tensile physical properties, even when an active energy ray non-curable adhesive is used for the adhesive layer 12, it is excellent in pick-up property when picking up a chip from the workpiece processing sheet 1. Specifically, the amount of pushing up of the pin or needle used to push up the chip at the time of pick-up can be suppressed to be small. As a result, it is possible to effectively suppress damage such as the chip being damaged due to the pushing up. The reason why excellent pick-up property is obtained because the base material 11 has the above-described tensile physical properties is considered that the base material 11 becomes relatively hard and is difficult to follow the chip to be picked up, and a trigger for the chip to peel off from the adhesive layer can be created. Also, the reason why excellent pick-up property is obtained because the surface layer 111 contains an antistatic agent is not necessarily clear, but it is considered that the adhesive force of the adhesive layer 12 is reduced by some action.

[0029] From the perspective of obtaining excellent pick-up properties, in the base material 11 of the present embodiment, the tensile stress at 20% and 50% of the tensile elongation in the above tensile test is preferably 8 MPa or more, and more preferably 8.5 MPa or more. Also, from the same perspective of obtaining excellent pick-up properties, the tensile stress is preferably 30 MPa or less, more preferably 20 MPa or less, and particularly preferably 15 MPa or less.

[0030] From the perspective of obtaining excellent pick-up properties, in the base material 11 of the present embodiment, the tensile stress at 10% of the tensile elongation in the above tensile test is preferably 7.5 MPa or more, and particularly preferably 8 MPa or more. Also, from the same perspective of obtaining excellent pick-up properties, the tensile stress at 10% of the tensile elongation is preferably 20 MPa or less, and particularly preferably 15 MPa or less.

[0031] 1. Configuration of the sheet for workpiece processing 1-1. Base material As described above, the base material 11 in the present embodiment includes a surface layer 111, an intermediate layer 112, and a back surface layer 113.

[0032] (1) Surface layer In the sheet 1 for workpiece processing according to the present embodiment, the surface layer 111 contains an antistatic agent. Thereby, excellent antistatic properties can be obtained, and the pick-up properties are also excellent.

[0033] The antistatic agent in the present embodiment is not particularly limited, and known ones can be used. Examples of the antistatic agent include low molecular weight antistatic agents and high molecular weight antistatic agents. From the perspective of obtaining excellent pick-up properties and the perspective that bleed-out is less likely to occur from the formed layer, a high molecular weight antistatic agent is preferred.

[0034] Examples of the polymer antistatic agent include copolymers having a polyether unit, such as polyether ester amide and polyether polyolefin block copolymer. These copolymers may contain metal salts such as alkali metal salts and alkaline earth metal salts, and ionic liquids.

[0035] The content of the antistatic agent in the surface layer 111 is preferably 3% by mass or more, particularly preferably 5% by mass or more, and more preferably 10% by mass or more. Thereby, the antistatic property and the pick-up property become more excellent. Further, the content is preferably 40% by mass or less, particularly preferably 35% by mass or less, and more preferably 30% by mass or less. Thereby, it becomes easier to satisfy the above-described tensile physical properties.

[0036] The material other than the antistatic agent constituting the surface layer 111 is not particularly limited as long as the above-described tensile physical properties are satisfied. However, in order to satisfy the above-described tensile physical properties, it is preferable to contain at least one of a polyolefin resin and an olefin thermoplastic elastomer (hereinafter sometimes referred to as "olefin elastomer"). In particular, it preferably contains at least a polyolefin resin, and further preferably contains an olefin elastomer or another thermoplastic elastomer as desired. According to these components, it becomes easier to satisfy the above-described tensile physical properties, and the pick-up property becomes more excellent.

[0037] In this specification, the polyolefin resin refers to a homopolymer or copolymer having an olefin as a monomer, or a copolymer having an olefin and a molecule other than an olefin as monomers, and the mass ratio of the portion based on the olefin unit in the resin after polymerization is 1.0% by mass or more. The "olefin elastomer" is a copolymer containing a structural unit derived from an olefin or a derivative thereof (olefin compound), and has rubber-like elasticity in a temperature range including room temperature and has thermoplasticity.

[0038] The polyolefin resin is not particularly limited as long as it does not inhibit the above-described tensile physical properties and can achieve the desired effects. The polymer constituting the polyolefin resin may be linear or may have side chains. It may also have an aromatic ring or an aliphatic ring.

[0039] Examples of the olefin monomer constituting the polyolefin resin include olefin monomers having 2 to 8 carbon atoms, α-olefin monomers having 3 to 18 carbon atoms, and olefin monomers having a cyclic structure. Examples of the olefin monomer having 2 to 8 carbon atoms include ethylene, propylene, 2-butene, and octene. Examples of the α-olefin monomer having 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 the olefin monomer having a cyclic structure include norbornene, cyclopentadiene, cyclohexadiene, dicyclopentadiene, and tetracyclododecene and their derivatives.

[0040] The polyolefin resin can be used alone or in combination of two or more.

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

[0042] Examples of the above polypropylene generally include homopolypropylene, random polypropylene, and block polypropylene. These can be used alone or in combination of two or more. In this embodiment, from the viewpoint of facilitating good expansion, it is preferable to use random polypropylene.

[0043] When the polyolefin resin contains polyethylene, the polyethylene may be any one 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.

[0044] The content of the polyolefin resin in the surface layer 111 is preferably 20% by mass or more, particularly preferably 23% by mass or more, and more preferably 25% by mass or more. Also, the content is preferably 60% by mass or less, particularly preferably 58% by mass or less, and more preferably 56% by mass or less. When the content of the polyolefin resin is within the above range, it becomes easier to achieve the above-described tensile physical properties, and the pick-up property becomes more excellent.

[0045] Examples of the olefin-based elastomer include those containing at least one resin 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.

[0046] When the surface layer 111 contains an olefin-based elastomer, the content of the olefin-based elastomer in the surface layer 111 is preferably 25% by mass or more, particularly preferably 30% by mass or more, and more preferably 35% by mass or more. Also, the content is preferably 75% by mass or less, particularly preferably 70% by mass or less, and more preferably 65% by mass or less. When the content of the olefin-based elastomer in the surface layer 111 is within the above range, it becomes easier to achieve the above-described tensile physical properties, and the pick-up property becomes more excellent.

[0047] The surface layer 111 preferably contains a thermoplastic elastomer other than an olefin-based elastomer, particularly a styrene-based thermoplastic elastomer (hereinafter sometimes referred to as a "styrene-based elastomer"). A styrene-based elastomer is a copolymer containing a structural unit derived from styrene or its derivative (styrene-based compound), and has rubber-like elasticity in a temperature range including room temperature and also has thermoplasticity. By containing a styrene-based elastomer in the surface layer 111, the generation of cutting pieces during dicing can be reduced.

[0048] Examples of the styrene-based elastomer include styrene-conjugated diene copolymers and styrene-olefin copolymers, among which styrene-conjugated diene copolymers are preferred. Specific examples of the styrene-conjugated diene copolymer include unhydrogenated styrene-conjugated diene copolymers such as styrene-butadiene copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-butadiene-butylene-styrene copolymer, styrene-isoprene copolymer, styrene-isoprene-styrene copolymer (SIS), styrene-ethylene-isoprene-styrene copolymer; hydrogenated styrene-conjugated diene copolymers such as styrene-ethylene / propylene-styrene copolymer (SEPS: a hydrogenated product of styrene-isoprene-styrene copolymer), styrene-ethylene-butylene-styrene copolymer (SEBS: a hydrogenated product of styrene-butadiene copolymer), styrene-ethylene / ethylene·propylene-styrene copolymer (SEEPS), etc. The styrene-based thermoplastic elastomer may be a hydrogenated product (hydrogenated material) or an unhydrogenated material, but a hydrogenated product is preferred. Among the above, from the viewpoint of easily achieving the above-described tensile physical properties, a hydrogenated styrene-conjugated diene copolymer is preferred, and particularly styrene-ethylene / ethylene·propylene-styrene copolymer (SEEPS) is preferred.

[0049] The content of the structural unit derived from styrene or a styrene-based compound in the styrene-based elastomer is preferably 5% by mass or more, particularly preferably 7% by mass or more, and even more preferably 10% by mass or more. Also, the content of the above structural unit is preferably 50% by mass or less, particularly preferably 45% by mass or less, and even more preferably 40% by mass or less. When the content of the above structural unit is within the above range, it becomes easier to achieve the above-described tensile physical properties.

[0050] When the surface layer 111 contains a styrene-based elastomer, the content of the styrene-based elastomer in the surface layer 111 is preferably 5% by mass or more, particularly preferably 10% by mass or more. Also, the content is preferably 40% by mass or less, particularly preferably 30% by mass or less, and even more preferably 20% by mass or less. When the content of the styrene-based elastomer in the surface layer 111 is within the above range, it becomes easier to satisfy the above-described tensile physical properties and to reduce the generation of cutting pieces during dicing.

[0051] The surface layer 111 may contain other components other than the above-described components, for example, components used for the base material of a general work processing sheet. Examples of such components include various additives such as flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers. Although the content of these additives is not particularly limited, it is preferably within a range in which the surface layer 111 exhibits a desired function.

[0052] (2) Intermediate layer In the present embodiment, the material constituting the intermediate layer 112 is not particularly limited as long as the above-described tensile physical properties are satisfied. However, in order to satisfy the above-described tensile physical properties, it is preferable to contain at least one of a polyolefin-based resin and an olefin-based elastomer. In particular, it preferably contains at least a polyolefin-based resin, and if desired, it is more preferable to further contain an olefin-based elastomer or other thermoplastic elastomers. According to these components, the above-described tensile physical properties are more easily satisfied, and the pick-up property becomes more excellent.

[0053] Preferred polyolefin-based resins, olefin-based elastomers, and styrene-based elastomers are the same as those exemplified in the surface layer 111, respectively.

[0054] The content of the polyolefin-based resin in the intermediate layer 112 is preferably 5% by mass or more, particularly preferably 7% by mass or more. Also, the content is preferably 95% by mass or less, particularly preferably 90% by mass or less. When the content of the polyolefin-based resin in the intermediate layer 112 is within the above range, the above-described tensile physical properties are more easily achieved, and the pick-up property becomes more excellent.

[0055] When the intermediate layer 112 contains an olefin-based elastomer, the content of the olefin-based elastomer in the intermediate layer 112 is preferably 10% by mass or more, particularly preferably 30% by mass or more, and more preferably 50% by mass or more. Also, the content is preferably 90% by mass or less, particularly preferably 80% by mass or less, and more preferably 70% by mass or less. When the content of the olefin-based elastomer in the intermediate layer 112 is within the above range, the above-described tensile physical properties are more easily achieved, and the pick-up property becomes more excellent.

[0056] When the intermediate layer 112 contains a styrenic elastomer, the content of the styrenic elastomer in the intermediate layer 112 is preferably 5% by mass or more, particularly preferably 10% by mass or more. Also, the content is preferably 30% by mass or less, particularly preferably 20% by mass or less. When the content of the styrenic elastomer in the intermediate layer 112 is within the above range, it becomes easier to achieve the above-described tensile physical properties, and the pick-up property becomes more excellent.

[0057] Here, although the intermediate layer 112 may also contain an antistatic agent, since the antistatic agent may soften the layer to be formed, from the viewpoint of pick-up property, it is preferable that the intermediate layer 112 does not contain an antistatic agent. When the intermediate layer 112 contains an antistatic agent, the intermediate layer 112 preferably contains the antistatic agent in a content (unit: mass%) less than that of the surface layer 111 and the back surface layer 113. Specifically, the content is preferably less than 5% by mass, more preferably less than 3% by mass, particularly preferably less than 1% by mass, and most preferably 0% by mass in the intermediate layer 112. When the intermediate layer 112 contains an antistatic agent, the lower limit value of the content is, for example, 0.01% by mass or more.

[0058] Similar to the surface layer 111, the intermediate layer 112 may contain other components other than the above-described components, for example, components used for the base material of a general work processing sheet.

[0059] (3) Back surface layer In the present embodiment, the back surface layer 113 contains an antistatic agent. Thereby, excellent antistatic property can be obtained.

[0060] As the antistatic agent in the back surface layer 113, the same one as the antistatic agent in the surface layer 111 can be used.

[0061] The content of the antistatic agent in the inner layer 113 is preferably 3% by mass or more, particularly preferably 20% by mass or more, and even more preferably 30% by mass or more. Thereby, it becomes easy to exhibit good antistatic properties. Further, the content is preferably 50% by mass or less, particularly preferably 45% by mass or less, and even more preferably 40% by mass or less. Thereby, it becomes easier to achieve the above-described tensile physical properties.

[0062] The material other than the antistatic agent constituting the inner layer 113 is not particularly limited as long as the above-described tensile physical properties are satisfied. However, in order to satisfy the above-described tensile physical properties, it is preferable to contain at least one of a polyolefin-based resin and an olefin-based elastomer. In particular, it is preferable to contain an olefin-based elastomer, or to contain a polyolefin-based resin and an olefin-based elastomer or another thermoplastic elastomer, particularly a styrene-based elastomer. According to these components, it becomes easy to satisfy the above-described tensile physical properties, and the pick-up property becomes more excellent.

[0063] The preferable polyolefin-based resin, olefin-based elastomer, and styrene-based elastomer are the same as those exemplified in the surface layer 111.

[0064] When the inner layer 113 contains a polyolefin-based resin, the content of the polyolefin-based resin in the inner layer 113 is preferably 20% by mass or more, particularly preferably 25% by mass or more, and even more preferably 30% by mass or more. Further, the content is preferably 85% by mass or less, particularly preferably 80% by mass or less, and even more preferably 75% by mass or less. When the content of the polyolefin-based resin in the inner layer 113 is within the above range, it becomes easier to achieve the above-described tensile physical properties, and the pick-up property becomes more excellent.

[0065] When the back surface layer 113 contains an olefin-based elastomer, the content of the olefin-based elastomer in the back surface layer 113 is preferably 30% by mass or more, particularly preferably 40% by mass or more, and still more preferably 50% by mass or more. Also, the content is preferably 85% by mass or less, particularly preferably 80% by mass or less, and still more preferably 75% by mass or less. When the content of the olefin-based elastomer in the back surface layer 113 is within the above range, it becomes easier to achieve the above-described tensile physical properties, and the pick-up property becomes more excellent.

[0066] When the back surface layer 113 contains a styrene-based elastomer, the content of the styrene-based elastomer in the back surface layer 113 is preferably 5% by mass or more, particularly preferably 10% by mass or more. Also, the content is preferably 40% by mass or less, particularly preferably 30% by mass or less, and still more preferably 20% by mass or less. When the content of the styrene-based elastomer in the back surface layer 113 is within the above range, it becomes easier to achieve the above-described tensile physical properties, and the pick-up property becomes more excellent.

[0067] Similar to the surface layer 111 and the intermediate layer 112, the back surface layer 113 may contain other components other than the above-described components, for example, components used for the base material of a general work processing sheet.

[0068] (4) Surface treatment of the base material On the surface of the base material 11 where the adhesive layer 12 is laminated, in order to enhance the adhesion with the adhesive layer 12, surface treatments such as primer treatment, corona treatment, plasma treatment, roughening treatment (mat processing), etc. may be performed. Examples of the roughening treatment include an embossing method, a sandblasting method, etc. Among these, it is preferable to perform corona treatment.

[0069] (5) Manufacturing method of the base material The manufacturing method of the base material 11 in the present embodiment is not particularly limited. For example, melt extrusion methods such as the T-die method and the round-die method; the calendar method; solution methods such as the dry method and the wet method can be used. Among these, from the perspective of efficiently manufacturing the base material, it is preferable to adopt the melt extrusion method, and particularly preferable to adopt the T-die method.

[0070] Further, when the base material 11 is manufactured by the melt extrusion method, the components constituting each layer are kneaded respectively, and from the obtained kneaded product directly or after once manufacturing pellets, a known extruder can be used to simultaneously extrude (co-extrude) a plurality of layers to form a film.

[0071] (6) Physical properties of the base material, etc. (6-1) Thickness In the present embodiment, the thickness of the surface layer 111 is preferably 10 μm or less, particularly preferably 8 μm or less, and more preferably 4 μm or less. Thus, since the thickness of the surface layer 111 located proximal to the adhesive layer 12 is thin, while exhibiting the desired antistatic property, it becomes easier to satisfy the above-described tensile physical properties.

[0072] Also, the thickness of the surface layer 111 is preferably 1 μm or more, particularly preferably 2 μm or more, and more preferably 3 μm or more. Thereby, it becomes easier to exhibit good antistatic property, and the pick-up property becomes more excellent.

[0073] In the present embodiment, the thickness of the intermediate layer 112 is preferably 40 μm or more, particularly preferably 50 μm or more, and more preferably 60 μm or more. Thereby, it becomes easier to satisfy the above-described tensile physical properties, and the pick-up property becomes more excellent. Also, the work processing sheet 1 is likely to have appropriate strength, and it becomes easier to favorably support the work fixed on the work processing sheet 1. The thickness of the intermediate layer 112 is preferably 100 μm or less, particularly preferably 90 μm or less, and more preferably 80 μm or less. Thereby, it becomes easier to satisfy the above-described tensile physical properties.

[0074] In the present embodiment, the thickness of the back surface layer 113 is preferably 2 μm or more, particularly preferably 4 μm or more, and even more preferably 8 μm or more. Thereby, the antistatic property of the work processing sheet 1 becomes more excellent. Further, the thickness of the back surface layer 113 is preferably 40 μm or less, particularly preferably 30 μm or less, and even more preferably 25 μm or less. Thereby, it becomes easier to satisfy the above-described tensile physical properties.

[0075] In the present embodiment, the thickness of the entire base material 11 is preferably 50 μm or more, particularly preferably 60 μm or more, and even more preferably 70 μm or more. Also, the thickness is preferably 140 μm or less, particularly preferably 120 μm or less, and even more preferably 100 μm or less. When the thickness of the entire base material 11 is within the above range, it becomes easier to satisfy the above-described tensile physical properties, and it also becomes easier to favorably support the work fixed on the work processing sheet 1.

[0076] (6-2) Surface Resistivity The surface resistivity of the surface on the surface layer 111 side of the base material 11 is preferably 1.0×10 13 Ω / square or less, particularly preferably 1.0×10 12 Ω / square or less, and even more preferably 1.0×10 11 Ω / square or less. Thereby, the work processing sheet 1 according to the present embodiment can exhibit excellent antistatic property. Note that the lower limit value of the above surface resistivity is not particularly limited, and for example, it may be 1.0×10 8 Ω / square or more, particularly preferably 1.0×10 9 Ω / square or more. Details of the method for measuring the surface resistivity in this specification are as described in the test examples described later.

[0077] 1-2. Adhesive Layer The pressure-sensitive adhesive that constitutes the pressure-sensitive adhesive layer 12 in the present embodiment is a non-curable pressure-sensitive adhesive for active energy rays. The non-curable pressure-sensitive adhesive for active energy rays is not particularly limited as long as it can exhibit sufficient adhesive force to the adherend (particularly, the adhesive force to the workpiece sufficient for processing the workpiece). Examples of the non-curable pressure-sensitive adhesive for active energy rays include acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, polyvinyl ether-based pressure-sensitive adhesives, and the like. Among these, from the viewpoint of easily exhibiting a desired adhesive force, it is preferable to use an acrylic pressure-sensitive adhesive.

[0078] The acrylic pressure-sensitive adhesive as the non-curable pressure-sensitive adhesive for active energy rays is preferably composed of an acrylic copolymer (A) and a crosslinking agent (B). The acrylic copolymer (A) preferably contains a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth)acrylic acid ester monomer or a derivative thereof. In the present specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.

[0079] The functional group-containing monomer as the structural unit of the acrylic copolymer (A) is preferably a monomer having a polymerizable double bond and a functional group such as a hydroxy group, a carboxy group, an amino group, a substituted amino group, and an epoxy group in the molecule. Among these, it is preferable to use a monomer having a hydroxy group in the molecule (hydroxy group-containing monomer) that is excellent in reactivity with the crosslinking agent (B), particularly the isocyanate-based crosslinking agent described later.

[0080] Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like. These may be used alone or in combination of two or more.

[0081] The acrylic copolymer (A) preferably contains, by 3% by mass or more, particularly preferably 7% by mass or more, of the structural unit derived from the functional group-containing monomer. Further, the acrylic copolymer (A) preferably contains, by 20% by mass or less, particularly preferably 15% by mass or less, of the structural unit derived from the functional group-containing monomer. By the content of the structural unit derived from the functional group-containing monomer being within the above range, an adhesive having a predetermined adhesive force and a crosslink density suitable for pick-up property can be obtained.

[0082] As the (meth)acrylic acid ester monomer constituting the acrylic copolymer (A), from the viewpoint of adhesiveness, a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 20 carbon atoms is preferable. Examples of the (meth)acrylic acid alkyl ester having an alkyl group with 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, and the like.

[0083] Among these, from the viewpoint of efficiently imparting adhesive force, a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 12 carbon atoms is more preferable, and an acrylic acid alkyl ester having an alkyl group with 1 to 10 carbon atoms is particularly preferable. Specifically, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferably mentioned. These may be used alone or in combination of two or more.

[0084] Among these, it is preferable to use methyl (meth)acrylate and 2-ethylhexyl (meth)acrylate, particularly methyl methacrylate and 2-ethylhexyl acrylate, in combination. Thereby, it is easy to obtain an adhesive having an excellent balance between adhesiveness and pick-up property. Their mass ratio is preferably from 5:95 to 25:75.

[0085] The acrylic copolymer (A) preferably contains 70% by mass or more, particularly preferably 75% by mass or more, of structural units derived from the above (meth)acrylate monomer. Further, the acrylic copolymer (A) preferably contains the structural units derived from the above (meth)acrylate monomer at 97% by mass or less, particularly preferably 90% by mass or less.

[0086] The acrylic copolymer (A) can be obtained by copolymerizing the functional group-containing monomer as described above and a (meth)acrylate monomer or its derivative by a conventional method. In addition to these monomers, dimethylacrylamide, vinyl acetate, styrene, etc. may be copolymerized.

[0087] The weight average molecular weight (Mw) of the acrylic copolymer (A) is preferably 300,000 or more, particularly preferably 400,000 or more, and more preferably 500,000 or more. Further, the weight average molecular weight (Mw) is preferably 1,500,000 or less, particularly preferably 1,200,000 or less, and more preferably 1,000,000 or less. Thereby, it is easy to obtain an adhesive having an excellent balance between adhesiveness and pick-up property. The weight average molecular weight (Mw) in this specification is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC method).

[0088] The crosslinking agent (B) may be any one that reacts with the functional groups of the acrylic copolymer (A). For example, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, ammonium salt-based crosslinking agents, etc. may be mentioned. The crosslinking agent (B) can be used alone or in combination of two or more kinds.

[0089] Here, when the acrylic copolymer (A) contains a hydroxyl group-containing monomer as a constituent monomer unit, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with hydroxyl groups as the crosslinking agent (B).

[0090] The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, etc., and their biuret bodies, isocyanurate bodies, and further adduct bodies which are reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. Among them, from the viewpoint of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable.

[0091] The blending amount of the crosslinking agent (B) is preferably 0.1 part by mass or more, particularly preferably 1 part by mass or more, and even more preferably 3 parts by mass or more with respect to 100 parts by mass of the acrylic copolymer (A). Further, the blending amount of the crosslinking agent (B) is preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less with respect to 100 parts by mass of the acrylic copolymer (A). When the blending amount of the crosslinking agent (B) is within the above range, an adhesive having a predetermined adhesive strength and a crosslinking density suitable for pick-up property can be obtained.

[0092] The thickness of the adhesive layer 12 in the present embodiment is preferably 1 μm or more, particularly preferably 3 μm or more, and even more preferably 5 μm or more. Further, the thickness of the adhesive layer 12 is preferably 50 μm or less, particularly preferably 30 μm or less, and even more preferably 15 μm or less. When the thickness of the adhesive layer 12 is within the above range, a good balance between the adhesive strength and the pick-up property can be achieved.

[0093] 1-3. Release sheet In the sheet 1 for workpiece processing according to the present embodiment, a release sheet may be laminated on the surface of the adhesive layer 12 on the side opposite to the base material 11 (hereinafter sometimes referred to as the "adhesive surface") for the purpose of protecting the surface until it is attached to the workpiece.

[0094] The structure of the release sheet is arbitrary, and examples include those obtained by subjecting a plastic film to a release treatment with a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, silicone-based, fluorine-based, long-chain alkyl-based, etc. can be used, and among these, silicone-based which can obtain inexpensive and stable performance is preferable.

[0095] There is no particular limitation on the thickness of the release sheet, and for example, it may be 16 μm or more and 250 μm or less.

[0096] 1-4. Others In the work processing sheet 1 according to the present embodiment, an adhesive layer may be laminated on the surface of the adhesive layer 12 opposite to the base material 11. In this case, the work processing sheet 1 according to the present embodiment can be used as a dicing / die bonding sheet. In the sheet, a work is attached to the surface of the adhesive layer opposite to the adhesive layer 12, and the adhesive layer is diced together with the work, whereby a chip with the fragmented adhesive layers laminated thereon can be obtained. The chip can be easily fixed to the object on which the chip is mounted by the fragmented adhesive layers. As the material constituting the above-described adhesive layer, it is preferable to use those containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, those containing a B-stage (semi-cured state) thermosetting adhesive component, and the like.

[0097] Further, in the work processing sheet 1 according to the present embodiment, a protective film forming layer may be laminated on the adhesive surface of the adhesive layer 12. In this case, the work processing sheet 1 according to the present embodiment can be used as a protective film forming and dicing sheet. In such a sheet, a work is attached to the surface of the protective film forming layer opposite to the adhesive layer 12, and the protective film forming layer is diced together with the work, whereby a chip with the fragmented protective film forming layers laminated thereon can be obtained. As the work, it is preferable to use one having a circuit formed on one side, and in this case, usually, the protective film forming layer is laminated on the surface opposite to the surface on which the circuit is formed. The fragmented protective film forming layer can be cured at a predetermined timing to form a protective film having sufficient durability on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

[0098] 2. Manufacturing method of work processing sheet The manufacturing method of the sheet 1 for work processing according to this embodiment is not particularly limited. For example, after forming the adhesive layer 12 on the release sheet, it is preferable to obtain the sheet 1 for work processing by laminating the surface of the base material 11 on the side of the surface layer 111 on the surface of the adhesive layer 12 opposite to the release sheet.

[0099] The formation of the above-mentioned adhesive layer 12 can be carried out by a known method. For example, an adhesive composition for forming the adhesive layer 12 and, if desired, a coating solution further containing a solvent or a dispersion medium are prepared. Then, the coating solution is applied to the surface of the release sheet having releasability (hereinafter sometimes referred to as the "release surface"). Subsequently, the obtained coating film is dried to form the adhesive layer 12.

[0100] The application of the above-mentioned coating solution can be carried out by a known method, for example, by a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc. The properties of the coating solution are not particularly limited as long as it can be applied. It may contain the components for forming the adhesive layer 12 as a solute or as a disperse phase. Further, the release sheet may be peeled off as a process material, or may protect the adhesive layer 12 until it is attached to the adherend.

[0101] When the adhesive composition for forming the adhesive layer 12 contains the above-mentioned cross-linking agent, by changing the above drying conditions (temperature, time, etc.) or by providing a separate heat treatment, the cross-linking reaction between the polymer component and the cross-linking agent in the coating film is allowed to proceed, and it is preferable to form a cross-linked structure with a desired density of existence in the adhesive layer 12. Further, in order to allow the above-mentioned cross-linking reaction to proceed sufficiently, after laminating the adhesive layer 12 and the base material 11, curing may be carried out, for example, by leaving it standing in an environment of 23°C and a relative humidity of 50% for several days.

[0102] 3. Method of using the sheet for work processing The work processing sheet 1 according to this embodiment can be used for processing works such as semiconductor wafers. That is, after attaching the adhesive surface of the work processing sheet 1 according to this embodiment to the work, the work can be processed on the work processing sheet 1. Depending on the processing, the work processing sheet 1 according to this embodiment will be used as a back grinding sheet, a dicing sheet, an expand sheet, a pickup sheet, or the like. Here, examples of the work include semiconductor members such as semiconductor wafers and semiconductor packages, and glass members such as glass plates.

[0103] As described above, the work processing sheet 1 according to this embodiment is excellent in pick-up property, and thus is preferably a sheet used in a process including at least a pick-up process. For example, it may be a dicing sheet used from dicing to pick-up, or a transfer sheet to which chips obtained by dicing are transferred and used for pick-up.

[0104] Also, as described above, the work processing sheet 1 according to this embodiment has excellent antistatic properties. The work processing sheet 1 according to this embodiment can suppress peeling electrification when separating the release sheet or separating the work. Further, the work processing sheet 1 according to this embodiment can also effectively suppress peeling electrification when pulling the work processing sheet from the spinner table after cleaning and drying the chips with the work processing sheet fixed to the spinner table. Therefore, the work processing sheet 1 according to this embodiment can also be suitably used for such cleaning and drying.

[0105] When the work processing sheet 1 according to this embodiment includes the adhesive layer described above, the work processing sheet 1 can be used as a dicing / die bonding sheet. Further, when the work processing sheet 1 according to this embodiment includes the protective film forming layer described above, the work processing sheet 1 can be used as a protective film forming and dicing sheet.

[0106] The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[0107] For example, another layer may be laminated between the base material 11 and the adhesive layer 12 in the sheet 1 for workpiece processing according to the present embodiment, or on the surface of the base material 11 opposite to the adhesive layer 12. Further, other layers may be laminated on the surface 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 surface layer 113, and on the surface of the back surface layer 113 opposite to the intermediate layer 112, respectively.

Example

[0108] Hereinafter, the present invention will be described more specifically by way of examples and the like, but the scope of the present invention is not limited to these examples and the like.

[0109] 〔Example 1〕 (1) Preparation of base material 28 parts by mass of random polypropylene resin (manufactured by Japan Polypropylene Co., Ltd., product name "Novatec FX3B"), 42 parts by mass of olefin-based elastomer (manufactured by Japan Polypropylene Co., Ltd., product name "Wellnex RFX4V"), and 30 parts by mass of polymer type antistatic agent (manufactured by Sanyo Chemical Industries, Ltd., product name "Perektron PVH") were each dried and then kneaded in a twin-screw kneader to obtain pellets for the surface layer.

[0110] Also, 38 parts by mass of random polypropylene resin (manufactured by Japan Polypropylene Co., Ltd., product name "Novatec FX3B") and 62 parts by mass of olefin-based elastomer (manufactured by Japan Polypropylene Co., Ltd., product name "Wellnex RFX4V") were each dried and then kneaded in a twin-screw kneader to obtain pellets for the intermediate layer.

[0111] 65 parts by mass of an olefin-based elastomer (manufactured by Nippon Polypropylene Co., Ltd., product name "Wellnex RFX4V") and 35 parts by mass of a polymer type antistatic agent (manufactured by Sanyo Chemical Industries, Ltd., product name "Perektron PVH") were each dried and then kneaded in a twin-screw kneader to obtain pellets for the back layer.

[0112] Using the three types of pellets obtained as described above, coextrusion molding was performed with a small T-die extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name "Laboplastmill") to obtain a base material having a three-layer structure in which a surface layer with a thickness of 4 μm, an intermediate layer with a thickness of 68 μm, and a back layer with a thickness of 4 μm were laminated in that order.

[0113] (2) Preparation of the adhesive composition 78 parts by mass of 2-ethylhexyl acrylate, 12 parts by mass of methyl methacrylate, and 10 parts by mass of 2-hydroxyethyl acrylate were polymerized by solution polymerization to obtain a (meth)acrylate polymer. When the weight average molecular weight of this (meth)acrylate polymer was measured by the method described below, it was 800,000.

[0114] 100 parts by mass of the (meth)acrylate polymer obtained above (in terms of solid content, the same applies hereinafter) and 4.7 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate L") as a crosslinking agent were mixed in a solvent to obtain a coating solution of the adhesive composition.

[0115] (3) Formation of the adhesive layer The coating solution of the adhesive composition obtained in the above step (2) was applied to the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031") in which a silicone-based release agent layer was formed on one side of a polyethylene terephthalate film with a thickness of 38 μm, and dried at 90°C for 1 minute to obtain a laminate in which an adhesive layer (a) with a thickness of 5 μm was formed on the release sheet.

[0116] (4) Production of the adhesive sheet The surface layer side of the surface of the base material obtained in the above step (1) was subjected to corona treatment, and the surface on the adhesive layer side of the laminate obtained in the above step (3) was bonded to obtain a sheet for workpiece processing.

[0117] Here, the weight average molecular weight (Mw) described above is the weight average molecular weight in terms of standard polystyrene measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC). <Measurement conditions> · Measuring device: HLC-8320 manufactured by Tosoh Corporation · GPC column (passing in the following order): manufactured by Tosoh Corporation TSK gel superH-H TSK gel superHM-H TSK gel superH2000 · Measuring solvent: Tetrahydrofuran · Measuring temperature: 40 °C

[0118] 〔Examples 2 to 4, Comparative Example 1〕 A sheet for workpiece processing was produced in the same manner as in Example 1, except that the composition of the pellets for forming each layer of the base material and the thickness of each layer were changed as shown in Table 1.

[0119] In Example 2, 15 parts by mass of styrene-ethylene / ethylene·propylene-styrene block copolymer (SEEPS) (manufactured by Kuraray Co., Ltd., "Hybrar 7311F", styrene ratio: 12% by mass) was blended as a styrene-based elastomer in the surface layer, the intermediate layer, and the back surface layer, respectively.

[0120] In Comparative Example 1, 15 parts by mass of maleic anhydride adduct of ethylene-ethyl acrylate copolymer (manufactured by SK Functional polymer Co., Ltd., product name "BONDINE LX4110", ethyl acrylate content: 5% by mass, acid component amount: 3% by mass) as an acid-modified resin was further blended in the surface layer.

[0121] 〔Example 5〕 A base material (the same as the base material of Example 4) was produced in the same manner as in Example 1, except that the composition of the pellets for forming each layer of the base material and the thickness of each layer were changed as described in Table 1. On the other hand, an adhesive layer was formed in the same manner as in Example 1, except that the blending amount of the crosslinking agent was changed to 4.2 parts by mass, and a laminate in which an adhesive layer (b) with a thickness of 5 μm was formed on a release sheet was obtained. Using the above base material and the laminate, a work processing sheet was produced in the same manner as in Example 1.

[0122] [Example 6] A base material (the same as the base material of Example 4) was produced in the same manner as in Example 1, except that the composition of the pellets for forming each layer of the base material and the thickness of each layer were changed as described in Table 1. On the other hand, an adhesive layer was formed in the same manner as in Example 1, except that the blending amount of the crosslinking agent was changed to 3.8 parts by mass, and a laminate in which an adhesive layer (c) with a thickness of 5 μm was formed on a release sheet was obtained. Using the above base material and the laminate, a work processing sheet was produced in the same manner as in Example 1.

[0123] [Comparative Example 2] Using the same apparatus as in Example 1, a film made of a single-layer ethylene-methacrylic acid copolymer (manufactured by Mitsui Dow Chemical Co., Ltd., product name "Nuclel N0903HC") was produced. A film obtained by irradiating the surface on the adhesive layer lamination side with an electron beam of 10 kGy for 2.2 seconds once was used as the base material. Using this base material, a work processing sheet was produced in the same manner as in Example 1.

[0124] [Comparative Example 3] Using the same apparatus as in Example 1, a film made of a single-layer ethylene-methacrylic acid copolymer (manufactured by Mitsui Dow Chemical Co., Ltd., product name "Nuclel N0903HC") was produced. A film obtained by irradiating the surface on the adhesive layer lamination side with an electron beam of 10 kGy for 2.2 seconds twice was used as the base material. Using this base material, a work processing sheet was produced in the same manner as in Example 1.

[0125] [Test Example 1] (Tensile Test) The base materials produced in the examples and comparative examples were cut into test pieces measuring 10 mm × 120 mm, and the tensile stress at a temperature of 23°C and a relative humidity of 50% RH was measured in accordance with JIS K7161:2014. Specifically, after setting the above test pieces at a chuck distance of 100 mm using a tensile testing machine (manufactured by Shimadzu Corporation, product name "Autograph"), a tensile test was conducted at a speed of 200 mm / min, and the tensile stress (MPa) at tensile elongations of 10%, 20%, and 50% was measured. The measurement was performed in the extrusion direction (MD direction) during the molding of the base material. The results are shown in Table 2.

[0126] 〔Test Example 2〕(Evaluation of Pick-up Property) A silicon wafer ground to 150 μm with #2000 using a grinder (manufactured by DISCO Corporation, product name "DFG8540") was prepared.

[0127] After peeling off the release sheet from the work processing sheets produced in the examples and comparative examples, the exposed surface of the exposed adhesive layer was attached to the ground surface of the above silicon wafer using a tape mounter (manufactured by Lintec Corporation, product name "Adwill RAD2500m / 12"). Subsequently, a dicing ring frame was attached to the peripheral edge of the exposed surface in the work processing sheet (a position that does not overlap with the silicon wafer). Further, the work processing sheet was cut according to the outer diameter of the ring frame.

[0128] Next, using a dicing device (manufactured by DISCO Corporation, product name "DFD6362"), dicing was performed under the following dicing conditions to singulate the silicon wafer into chips with a size of 10 mm × 10 mm. <Dicing Conditions> Wafer thickness: 150 μm Blade: Manufactured by DISCO Corporation, product name "ZH05-SD2000-N1-50 CC" Blade rotation speed: 30000 rpm Cutting speed: 60 mm / sec Blade height: 0.060 mm Cutting water volume: 1.0 L / min Cutting water temperature: 20°C

[0129] After 4 hours and 24 hours from the attachment of the work processing sheet to the silicon wafer, using a pick-up device (manufactured by Canon Machinery, product name "BESTEM D02"), chips were picked up from the work processing sheet under the following pick-up conditions. Then, the amount of pin pushing-up required for chip pick-up was measured. The results are shown in Table 2. <Pick-up conditions> · Pick-up method: 4 pins · Pick-up speed: 5 mm / s · Amount of pin pushing-up: 550 - 800 μm

[0130] Based on the amount of pin pushing-up measured above, the pick-up property was evaluated according to the following criteria. The evaluation results are shown in Table 2. 〇: Amount of pin pushing-up is 600 mm or less ×: Amount of pin pushing-up exceeds 600 mm

[0131] 〔Test Example 3〕(Measurement of surface resistivity) The work processing sheets manufactured in the examples and comparative examples were cut into 100 mm × 100 mm, and these were used as samples for surface resistivity measurement. After conditioning the surface resistivity measurement samples at a temperature of 23°C and a relative humidity of 50% RH for 24 hours, the surface resistivity (Ω / □) of the surface layer side surface was measured at an applied voltage of 100 V using a DIGITAL ELECTROMETER (manufactured by Advantest). The results are shown in Table 2.

[0132] 〔Test Example 4〕(Evaluation of antistatic property) The work processing sheets manufactured in the examples and comparative examples were cut into B4 size, and these were used as samples. From the said samples, the release sheet was peeled at a speed of 10 cm / s. The charging voltage (V) of the sample immediately after peeling was measured from the substrate side using a charge voltage meter (manufactured by Prostat, product name "Fold Meter PFM - 711A"). Then, based on the following criteria, the antistatic property was evaluated. The charging voltage and evaluation results are shown in Table 2. ○: Charging voltage is 1 V or less ×: Charging voltage exceeds 1 V

[0133]

Table 1

[0134]

Table 2

[0135] As is clear from Table 2, the sheet for workpiece processing manufactured in the examples was excellent in both pick-up property and antistatic property.

Industrial Applicability

[0136] The sheet for workpiece processing of the present invention can be suitably used for processing workpieces such as semiconductor wafers.

Explanation of Signs

[0137] 1... Sheet for workpiece processing 11... Base material 111... Surface layer 112... Intermediate layer 113... Back layer 12... Adhesive layer

Claims

1. A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, The substrate comprises a surface layer located proximal to the pressure-sensitive adhesive layer, a back layer located distal to the pressure-sensitive adhesive layer, and an intermediate layer located between the surface layer and the back layer; the pressure-sensitive adhesive layer is made of an active energy ray non-curable pressure-sensitive adhesive, the front surface layer and the back surface layer contain an antistatic agent, When a tensile test is performed on the substrate under an environment of a temperature of 23° C. and a relative humidity of 50% RH, the tensile stress at a tensile elongation of 20% and 50% is 8 MPa or more and 30 MPa or less. A workpiece processing sheet characterized by the above.

2. 2. The workpiece processing sheet according to claim 1, wherein the non-curable active energy ray adhesive is an acrylic adhesive.

3. The workpiece processing sheet according to claim 1 or 2, characterized in that each of the surface layer, the intermediate layer and the back layer contains at least one of a polyolefin resin and an olefin thermoplastic elastomer.

4. The intermediate layer does not contain an antistatic agent, or The intermediate layer contains an antistatic agent in a content (unit: mass %) smaller than that of each of the front surface layer and the back surface layer. The workpiece processing sheet according to any one of claims 1 to 3.

5. The workpiece processing sheet according to any one of claims 1 to 4, characterized in that the antistatic agent is a polymer-type antistatic agent.

6. The surface resistivity of the surface of the pressure-sensitive adhesive layer opposite to the substrate is 1.0×10 １３ The workpiece processing sheet according to any one of claims 1 to 5, characterized in that it has a hardness of Ω / □ or less.

7. The workpiece processing sheet according to any one of claims 1 to 6, characterized in that it is a dicing sheet.

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