CN115148667A

CN115148667A - Sheet for processing workpiece

Info

Publication number: CN115148667A
Application number: CN202111544998.8A
Authority: CN
Inventors: 梅本夏树; 山口征太郎; 渡边周平
Original assignee: Lintec Corp
Current assignee: Lintec Corp
Priority date: 2021-03-31
Filing date: 2021-12-16
Publication date: 2022-10-04
Also published as: JP2022156391A; TW202239919A; KR20220136045A

Abstract

The invention provides a sheet for processing work, which has excellent pickup property and antistatic property even though an adhesive agent curable by non-active energy rays is used in an adhesive agent layer. The sheet for processing a workpiece is a sheet (1) for processing a workpiece, which is provided with a substrate (11) and an adhesive layer (12), wherein the substrate (11) is provided with a surface layer (111) that is close to the adhesive layer (12), a back surface layer (113) that is far from the adhesive layer (12), and an intermediate layer (112) that is positioned between the surface layer (111) and the back surface layer (113), the adhesive layer (12) is formed from an inactive energy ray-curable adhesive, the surface layer (111) and the back surface layer (113) contain an antistatic agent, and when the substrate (11) is subjected to a tensile test in an environment in which the temperature is 23 ℃ and the relative humidity is 50 RH, the tensile stress at tensile elongations of 20% and 50% is 8MPa or more and 30MPa or less.

Description

Sheet for processing workpiece

Technical Field

The present invention relates to a workpiece processing sheet used for processing a workpiece such as a semiconductor wafer.

Background

Semiconductor wafers such as silicon and gallium arsenide, and various packages (packages) are manufactured in a large-diameter state, cut (diced) into chips, and then peeled (picked up), and then transferred to a mounting (mount) step which is a next step. In this case, a work such as a semiconductor wafer is subjected to processing such as back grinding, dicing, cleaning, drying, spreading, picking up, and mounting in a state of being laminated on an adhesive sheet (hereinafter, sometimes referred to as a "work processing sheet") provided with a base material and an adhesive layer.

For example, the semiconductor wafer after completion of back grinding is attached to a sheet, and dicing is performed on the sheet. By dicing, the semiconductor wafer is singulated (singulated) into a plurality of semiconductor chips. Then, the plurality of semiconductor chips are picked up one by one from the chip.

In another method, after the dicing, the plurality of semiconductor chips supported on the sheet are transferred to another sheet, and the plurality of semiconductor chips are picked up one by one from the other sheet.

The pickup of the semiconductor chip from the chip as described above is performed using a device such as a die ejector. The device lifts the semiconductor chips one by one from the surface of the sheet opposite to the surface to which the semiconductor chips are attached, and separates the semiconductor chips from other semiconductor chips. By thus jacking up 1 semiconductor chip, pickup by the suction nozzle is easily performed. In addition, in this case, the sheet is expanded as necessary to create a gap between the semiconductor chips, so that the lifting and picking up can be facilitated.

As a jack-up method, there is a method using 1 or more pins or needles. In this manner, the tip of the pin or needle comes into point contact with the sheet and lifts the semiconductor chip up at a point. However, in recent years, as thinning of semiconductor chips has progressed, and use of a material which is hard and more easily broken as a semiconductor material has advanced, the semiconductor chips have become further fragile. When such a semiconductor chip is handled, if the amount of the pin or the needle pushed up is large, the semiconductor chip may be damaged.

On the other hand, as an adhesive of the adhesive layer of the work processing sheet, an ultraviolet curable adhesive is often used. In the case of an ultraviolet-curable adhesive, the adhesive layer is irradiated with ultraviolet rays before the semiconductor chip is picked up, and the adhesive is cured, whereby the adhesive strength can be reduced. 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, a non-ultraviolet-curable adhesive is sometimes desired instead of the ultraviolet-curable adhesive. In this case, it is more difficult to obtain good pickup properties than in the case of using an ultraviolet-curable adhesive.

Patent document 1 discloses a dicing film in which a base material is defined to contain a specific random polypropylene (a) and a specific olefin-based elastomer (B), and the 100% tensile stress of the olefin-based elastomer (B) is defined so as to obtain suitable extensibility and excellent pickup properties.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5494132

Disclosure of Invention

Technical problem to be solved by the invention

However, the work processing sheet is peeled from the adherend after completion of the predetermined treatment step, and in this case, static electricity called peeling electrification may be generated between the work processing sheet and the adherend. Such static electricity is a cause of dust or the like adhering to a workpiece or a device, and also a cause of breakage of the workpiece or the like. Therefore, the work processing sheet is also required to be provided with antistatic properties.

After the dicing process of the semiconductor wafer, the obtained chips are usually cleaned. Specifically, a workpiece processing sheet on which a plurality of chips are mounted is sucked and fixed to a rotary table, and the chips are cleaned with ultrapure water and then dried (air-dried) on the workpiece processing sheet. After these treatments, the workpiece processing sheet on which a plurality of chips are mounted is separated from the rotary table, and the inventors of the present application have confirmed that peeling electrification occurs even when this separation is performed.

However, the conventional sheet for processing a workpiece as in patent document 1 cannot cope with antistatic property, and the above-described problem of peeling electrification occurs.

The present invention has been made in view of such circumstances, and an object thereof is to provide a sheet for processing a workpiece, which has excellent pickup properties and excellent antistatic properties, even when an inactive energy ray-curable adhesive is used for an adhesive layer.

Means for solving the problems

In order to achieve the above object, the present invention provides a sheet for processing a workpiece, comprising a substrate and an adhesive layer laminated on one surface side of the substrate, wherein the substrate comprises a surface layer close to the adhesive layer, a back surface layer distant from the adhesive layer, and an intermediate layer located between the surface layer and the back surface layer, the adhesive layer is formed of an active energy ray-curable adhesive, the surface layer and the back surface layer contain an antistatic agent, and tensile stress is 8MPa or more and 30MPa or less when tensile elongation is 20% and 50% when the substrate is subjected to a tensile test in an environment in which a temperature is 23 ℃ and a relative humidity is 50 rh (invention 1).

In the above invention (invention 1), the surface layer and the back layer contain an antistatic agent, and thus have excellent antistatic properties. Further, by containing an antistatic agent in the surface layer and imparting the above-described tensile properties to the base material, even when an adhesive agent curable with an inactive energy ray is used in the adhesive agent layer, the pickup property when picking up a chip from the work processing sheet is excellent.

In the above invention (invention 1), the non-active energy ray-curable adhesive is preferably an acrylic adhesive (invention 2).

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

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

In the above inventions (inventions 1 to 4), the antistatic agent is preferably a polymer type antistatic agent (invention 5).

In the above inventions (inventions 1 to 5), the surface resistivity of the surface of the adhesive agent layer opposite to the substrate is preferably 1.0 × 10 ¹³ Omega/□ or less (invention 6).

In the above inventions (inventions 1 to 6), the work processing sheet is preferably a dicing sheet (invention 7).

Effects of the invention

The sheet for processing a workpiece of the present invention has excellent pickup properties and excellent antistatic properties, although an adhesive curable with actinic energy rays is used for the adhesive layer.

Drawings

Fig. 1 is a sectional view of a workpiece processing sheet according to an embodiment of the present invention.

Description of the reference numerals

1: a workpiece processing sheet; 11: a substrate; 111: a surface layer; 112: an intermediate layer; 113: a back layer; 12: an adhesive layer.

Detailed Description

Hereinafter, embodiments of the present invention will be described.

Fig. 1 shows a cross-sectional view of a workpiece-processing sheet according to an embodiment of the present invention. The work processing sheet 1 shown in fig. 1 includes a base material 11 and an adhesive layer 12 laminated on one surface of the base material 11.

As shown in fig. 1, the substrate 11 includes a surface layer 111 close to the adhesive layer 12, a back layer 113 distant from the adhesive layer 12, and an intermediate layer 112 located between the surface layer 111 and the back layer 113.

In the work processing sheet 1 of the present embodiment, the adhesive layer 12 is formed of an inactive energy ray-curable adhesive, and the surface layer 111 and the back surface layer 113 contain an antistatic agent. And, when the tensile test is performed on the base material 11 in an environment in which the temperature is 23 ℃ and the relative humidity is 50% rh, the tensile stress is 8MPa or more and 30MPa or less when the tensile elongation is 20% and 50%. Hereinafter, physical properties related to tensile stress may be referred to as "tensile physical properties". The specific measurement method of the tensile test in the present specification is shown in test examples described later.

By containing the antistatic agent in the surface layer 111 and the back surface layer 113, the sheet 1 for processing a work of the present embodiment has excellent antistatic properties. Therefore, peeling electrification at the time of separating the peeling sheet or the workpiece from the workpiece processing sheet 1 can be favorably suppressed. Further, even after the cleaning and drying of the workpiece on the workpiece processing sheet 1, peeling electrification at the time of separating the workpiece processing sheet 1 from the rotary table can be prevented favorably.

In addition, in the work processing sheet 1 of the present embodiment, by containing an antistatic agent in the surface layer 111 and imparting the tensile physical properties to the substrate 11, even when an active energy ray-curable adhesive is used in the adhesive layer 12, the pickup property when picking up a chip from the work processing sheet 1 is excellent. Specifically, the amount of pin or needle to be pushed up for pushing up the chip at the time of pickup can be suppressed to be small. As a result, the chip can be effectively prevented from being damaged due to the lifting. The reason why the substrate 11 has the above-described tensile physical properties and thus has excellent pickup properties is considered to be that the substrate 11 is relatively hard and is less likely to follow a picked-up chip, and a chance that the chip peels off from the adhesive layer is generated. The reason why excellent pickup properties are obtained by including an antistatic agent in the surface layer 111 is not necessarily determined, but it is considered that the adhesive force of the adhesive agent layer 12 is lowered by some action.

The tensile stress of the substrate 11 of the present embodiment is 8MPa or more, preferably 8.5MPa or more, when the tensile elongation is 20% and 50% in the tensile test, from the viewpoint of obtaining excellent pickup properties. Also, from the viewpoint of obtaining excellent pickup properties as well, the tensile stress is 30MPa or less, preferably 20MPa or less, and particularly preferably 15MPa or less.

The tensile stress at a tensile elongation of 10% in the tensile test is preferably 7.5MPa or more, and particularly preferably 8MPa or more, for the substrate 11 of the present embodiment, from the viewpoint of obtaining excellent pickup properties. Also, from the viewpoint of obtaining excellent pickup properties as well, the tensile stress at a tensile elongation of 10% is preferably 20MPa or less, and particularly preferably 15MPa or less.

1. Structure of sheet for working workpiece

1-1. Base material

As described above, the substrate 11 of the present embodiment includes the surface layer 111, the intermediate layer 112, and the back layer 113.

(1) Surface layer

In the sheet for workpiece processing 1 of the present embodiment, the surface layer 111 contains an antistatic agent. Thus, excellent antistatic properties can be obtained, and also excellent pickup properties can be obtained.

The antistatic agent of the present embodiment is not particularly limited, and a known antistatic agent can be used. Examples of the antistatic agent include a low-molecular antistatic agent and a high-molecular antistatic agent, and a high-molecular antistatic agent is preferable from the viewpoint of obtaining excellent pickup properties and from the viewpoint of being less likely to bleed out (bleedout) from a layer formed.

Examples of the polymer type antistatic agent include copolymers having polyether units such as polyether ester amides and polyether polyolefin block copolymers, and these copolymers may contain metal salts such as alkali metal salts and alkaline earth metal salts, or ionic liquids.

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. This further improves the antistatic property and the pickup property. The content is preferably 40% by mass or less, particularly preferably 35% by mass or less, and further preferably 30% by mass or less. This makes it easy to satisfy the tensile properties.

The material constituting the surface layer 111 other than the antistatic agent is not particularly limited as long as it satisfies the above tensile properties, and in order to satisfy the above tensile properties, it preferably contains at least one of a polyolefin resin and an olefinic thermoplastic elastomer (hereinafter, may be referred to as "olefinic elastomer"), and particularly preferably contains at least a polyolefin resin and further contains an olefinic elastomer or another thermoplastic elastomer as necessary. These components tend to satisfy the tensile properties described above, and the pickup property is further improved.

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

The polyolefin resin is not particularly limited as long as the above-mentioned tensile properties are not impaired and the desired effects can be obtained. The polymer constituting the polyolefin resin may be linear or have a side chain. Further, the aromatic ring or the aliphatic ring may be present.

Examples of the olefin monomer constituting the polyolefin-based resin include an olefin monomer having 2 to 8 carbon atoms, an α -olefin monomer having 3 to 18 carbon atoms, an olefin monomer having a cyclic structure, and the like. Examples of the olefin monomer having 2 to 8 carbon atoms include ethylene, propylene, 2-butene, octene, and the like. 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, tetracyclododecene, and derivatives thereof.

The polyolefin-based resin may be used singly or in combination of two or more.

In the specific example of the polyolefin-based resin, at least one of polyethylene containing ethylene as a main polymerization unit and polypropylene containing propylene as a main polymerization unit is preferably used.

Examples of the polypropylene include homopolypropylene, atactic polypropylene and block polypropylene. These polypropylenes may be used singly or in combination of two or more. In the present embodiment, random polypropylene is preferably used from the viewpoint that the expansion can be easily performed well.

When the polyolefin-based 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 thereof.

The content of the polyolefin-based resin in the surface layer 111 is preferably 20 mass% or more, particularly preferably 23 mass% or more, and more preferably 25 mass% or more. The content is preferably 60% by mass or less, particularly preferably 58% by mass or less, and further preferably 56% by mass or less. When the content of the polyolefin resin is within the above range, the above tensile properties can be more easily achieved, and the pickup property is more excellent.

As examples of the olefin-based elastomer, elastomers 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 can be cited. Among them, an ethylene-propylene copolymer is preferable.

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. 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 olefinic elastomer in the surface layer 111 is in the above range, the above tensile properties can be more easily achieved, and the pickup property is more excellent.

The surface layer 111 preferably contains a thermoplastic elastomer other than the olefinic elastomer, particularly a styrenic thermoplastic elastomer (hereinafter, sometimes referred to as "styrenic elastomer"). The styrene-based elastomer is a copolymer containing a structural unit derived from styrene or a derivative thereof (styrene-based compound), and is a material having rubber-like elasticity and simultaneously having thermoplasticity in a temperature region including normal temperature. By including the styrene-based elastomer in the surface layer 111, the occurrence of chips during dicing can be reduced.

Examples of the styrene-based elastomer include a styrene-conjugated diene copolymer and a styrene-olefin copolymer, and among them, a styrene-conjugated diene copolymer is preferable. 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-styrene copolymer (SIS), and styrene-ethylene-isoprene-styrene copolymer; styrene-ethylene/propylene-styrene copolymer (SEPS: hydrogenated styrene-conjugated diene copolymers such as styrene-isoprene-styrene copolymer, styrene-ethylene-butylene-styrene copolymer (SEBS: hydrogenated product of styrene-butadiene copolymer), styrene-ethylene/(ethylene-propylene) -styrene copolymer (SEEPS), and the like. The styrenic thermoplastic elastomer may be a hydrogenated product (hydride) or an unhydrogenated product, but is preferably a hydrogenated product. Among the above-mentioned styrene-conjugated diene copolymers, hydrogenated styrene-conjugated diene copolymers are preferred from the viewpoint of easy achievement of the above-mentioned tensile properties, and styrene-ethylene/(ethylene-propylene) -styrene copolymers (SEEPS) are particularly preferred.

The content of the structural units derived from styrene or styrene compound in the styrene-based elastomer is preferably 5% by mass or more, particularly preferably 7% by mass or more, and more preferably 10% by mass or more. The content of the structural unit is preferably 50% by mass or less, particularly preferably 45% by mass or less, and further preferably 40% by mass or less. When the content of the structural unit is within the above range, the tensile properties can be more easily achieved.

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, and particularly preferably 10% by mass or more. The content is preferably 40% by mass or less, particularly preferably 30% by mass or less, and further preferably 20% by mass or less. When the content of the styrene-based elastomer in the surface layer 111 is within the above range, the tensile properties described above can be easily satisfied, and the occurrence of chips during dicing can be reduced.

The surface layer 111 may contain other components than the above components, for example, components generally used for a base material of a sheet for workpiece processing. Examples of such components include various additives such as flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers. The content of these additives is not particularly limited, but is preferably within a range in which the surface layer 111 performs a desired function.

(2) Intermediate layer

In the present embodiment, the material constituting the intermediate layer 112 is not particularly limited as long as it satisfies the above-mentioned tensile properties, and in order to satisfy the above-mentioned tensile properties, it preferably contains at least one of a polyolefin resin and an olefin elastomer, and particularly preferably contains at least a polyolefin resin and further contains an olefin elastomer or another thermoplastic elastomer as necessary. These components can easily satisfy the tensile properties described above, and the pickup property is further excellent.

The preferred polyolefin resin, olefin elastomer, and styrene elastomer are the same as those exemplified for the surface layer 111.

The content of the polyolefin-based resin in the intermediate layer 112 is preferably 5% by mass or more, and particularly preferably 7% by mass or more. The content is preferably 95% by mass or less, and particularly preferably 90% by mass or less. When the content of the polyolefin resin in the intermediate layer 112 is within the above range, the above tensile properties can be more easily achieved, and the pickup property is more excellent.

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. 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 tensile properties can be more easily achieved, and the pickup properties are more excellent.

When the intermediate layer 112 contains a styrene-based elastomer, the content of the styrene-based elastomer in the intermediate layer 112 is preferably 5% by mass or more, and particularly preferably 10% by mass or more. The content is preferably 30% by mass or less, and particularly preferably 20% by mass or less. When the content of the styrene-based elastomer in the intermediate layer 112 is within the above range, the above tensile properties can be more easily achieved, and the pickup property is more excellent.

Here, although the intermediate layer 112 may contain an antistatic agent, it is preferable that the intermediate layer 112 does not contain an antistatic agent from the viewpoint of pickup property because the antistatic agent may soften the formed layer. When the intermediate layer 112 contains an antistatic agent, the intermediate layer 112 preferably contains the antistatic agent in a smaller content (unit: mass%) than the surface layer 111 and the back surface layer 113. Specifically, in the intermediate layer 112, the content of the antistatic agent 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. When the intermediate layer 112 contains an antistatic agent, the lower limit of the content thereof is, for example, 0.01 mass% or more.

As with the surface layer 111, the intermediate layer 112 may contain other components than the above components, for example, components commonly used for a base material of a sheet for workpiece processing.

(3) Back layer

In the present embodiment, the back surface layer 113 contains an antistatic agent. Thereby, excellent antistatic properties can be obtained.

As the antistatic agent in the back surface layer 113, the same antistatic agent as that in the surface layer 111 can be used.

The content of the antistatic agent in the back surface layer 113 is preferably 3% by mass or more, particularly preferably 20% by mass or more, and more preferably 30% by mass or more. This facilitates the development of good antistatic properties. The content is preferably 50% by mass or less, particularly preferably 45% by mass or less, and further preferably 40% by mass or less. This makes it easier to achieve the tensile properties.

The material other than the antistatic agent constituting the back layer 113 is not particularly limited as long as it satisfies the above tensile properties, and in order to satisfy the above tensile properties, it preferably contains at least one of a polyolefin resin and an olefin elastomer, and particularly preferably contains an olefin elastomer, or contains a polyolefin resin and an olefin elastomer or other thermoplastic elastomer, particularly a styrene elastomer. These components can easily satisfy the tensile properties described above, and the pickup property is further excellent.

When the back surface layer 113 contains a polyolefin resin, the content of the polyolefin resin in the back surface layer 113 is preferably 20 mass% or more, particularly preferably 25 mass% or more, and more preferably 30 mass% or more. The content is preferably 85% by mass or less, particularly preferably 80% by mass or less, and more preferably 75% by mass or less. When the content of the polyolefin resin in the back layer 113 is within the above range, the above tensile properties can be more easily achieved, and the pickup property is more excellent.

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 more preferably 50% by mass or more. The content is preferably 85% by mass or less, particularly preferably 80% by mass or less, and more preferably 75% by mass or less. When the content of the olefin-based elastomer in the back layer 113 is in the above range, the above tensile properties can be more easily achieved, and the pickup property is more excellent.

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, and particularly preferably 10% by mass or more. The content is preferably 40% by mass or less, particularly preferably 30% by mass or less, and more preferably 20% by mass or less. When the content of the styrene-based elastomer in the back layer 113 is within the above range, the above tensile properties can be more easily achieved, and the pickup property is more excellent.

The back surface layer 113 may contain other components than the above components, for example, components generally used for a substrate of a workpiece processing sheet, as in the case of the surface layer 111 and the intermediate layer 112.

(4) Surface treatment of substrates

In order to improve the adhesion between the surface of the substrate 11 on which the adhesive layer 12 is laminated and the adhesive layer 12, the surface may be subjected to surface treatment such as primer treatment (primer treatment), corona treatment, plasma treatment, or roughening treatment (frosting treatment). Examples of the roughening treatment include embossing and sand blasting. Among them, corona treatment is preferably performed.

(5) Method for producing base material

The method for producing the substrate 11 of the present embodiment is not particularly limited, and for example, a melt extrusion method such as a T-die method or a circular die method (pellet ダイ method); a rolling method; solution methods such as dry method and wet method. Among them, from the viewpoint of efficiently producing the base material, the melt extrusion method is preferably used, and the T-die method is particularly preferably used.

In the case of producing the substrate 11 by the melt extrusion method, the components constituting each layer may be kneaded separately, and the obtained kneaded product may be directly formed into a film, or the obtained kneaded product may be first formed into pellets (pellets), and then a plurality of layers may be simultaneously extruded (co-extruded) by a known extruder to form a film.

(6) Physical properties of the base material, etc

(6-1) thickness

The thickness of the surface layer 111 of the present embodiment is preferably 10 μm or less, particularly preferably 8 μm or less, and further preferably 4 μm or less. By making the thickness of the surface layer 111 close to the adhesive layer 12 thin in this way, the desired antistatic properties can be exhibited, and the above-described tensile physical properties can be easily satisfied.

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. This facilitates satisfactory antistatic performance and further improves the pickup property.

The thickness of the intermediate layer 112 in the present embodiment is preferably 40 μm or more, particularly preferably 50 μm or more, and more preferably 60 μm or more. This makes it easy to satisfy the tensile properties and further improves the pickup property. Further, the workpiece processing sheet 1 is likely to have appropriate strength, and the workpiece fixed to the workpiece processing sheet 1 is likely to be supported well. The thickness of the intermediate layer 112 is preferably 100 μm or less, particularly preferably 90 μm or less, and further preferably 80 μm or less. This makes it easy to satisfy the tensile properties.

The thickness of the back surface layer 113 of the present embodiment is preferably 2 μm or more, particularly preferably 4 μm or more, and more preferably 8 μm or more. This provides the work processing sheet 1 with more excellent antistatic properties. The thickness of the back surface layer 113 is preferably 40 μm or less, particularly preferably 30 μm or less, and further preferably 25 μm or less. This makes it easy to satisfy the tensile properties.

The thickness of the entire substrate 11 of the present embodiment is preferably 50 μm or more, particularly preferably 60 μm or more, and more preferably 70 μm or more. The thickness is preferably 140 μm or less, particularly preferably 120 μm or less, and more preferably 100 μm or less. When the thickness of the entire base material 11 is within the above range, the tensile properties described above are easily satisfied, and the workpiece fixed to the workpiece processing sheet 1 is easily supported satisfactorily.

(6-2) surface resistivity

The surface resistivity of the surface 111 side of the substrate 11 is preferably 1.0 × 10 ¹³ Omega/□ or less, particularly 1.0X 10 ¹² Omega/□ or less, more preferably 1.0X 10 ¹¹ Omega/□ or less. Thus, the sheet 1 for processing a workpiece of the present embodiment can exhibit excellent antistatic properties. The lower limit of the surface resistivity is not particularly limited, and may be, for example, 1.0 × 10 ⁸ Omega/□ or more, particularly 1.0 × 10 ⁹ Omega/□ or higher. The details of the method for measuring the surface resistivity in the present specification are shown in the test examples described later.

1-2. Adhesive layer

The adhesive constituting the adhesive layer 12 of the present embodiment is a non-active energy ray-curable adhesive. The non-active energy ray-curable adhesive is not particularly limited as long as it can exhibit sufficient adhesive force to an adherend (in particular, sufficient adhesive force to a work for work processing). As examples of the non-active energy ray-curable adhesive, examples of the adhesive include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives. Among them, acrylic adhesives are preferably used because they easily exert a desired adhesive force.

The acrylic adhesive, which is preferably an actinic-energy-ray-curable adhesive, is composed of an acrylic copolymer (a) and a crosslinking agent (B). Preferably, the acrylic copolymer (a) comprises a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth) acrylate monomer or a derivative thereof. In the present specification, (meth) acrylic acid refers to both acrylic acid and methacrylic acid. Other similar terms are also the same.

The functional group-containing monomer as a constituent unit of the acrylic copolymer (a) is preferably a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, an epoxy group, or the like in the molecule. Among them, a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer) which is excellent in reactivity with the crosslinking agent (B), particularly with an isocyanate-based crosslinking agent described later is preferably used.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate, and these hydroxyl group-containing monomers may be used alone or in combination of two or more.

The acrylic copolymer (a) preferably contains 3% by mass or more, particularly preferably contains 7% by mass or more of the structural unit derived from the functional group-containing monomer. The acrylic copolymer (a) preferably contains 20% by mass or less, particularly preferably 15% by mass or less of the structural unit derived from the functional group-containing monomer. By setting the content of the structural unit derived from the functional group-containing monomer within the above range, an adhesive having a predetermined adhesive force and a crosslinking density suitable for pickup properties can be obtained.

The (meth) acrylate monomer constituting the acrylic copolymer (a) is preferably an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms from the viewpoint of tackiness. Examples of the alkyl (meth) acrylate in which the alkyl group has 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, and stearyl (meth) acrylate.

Among the above-mentioned alkyl (meth) acrylates, the alkyl (meth) acrylate having an alkyl group with 1 to 12 carbon atoms is more preferable, and the alkyl acrylate having an alkyl group with 1 to 10 carbon atoms is particularly preferable, from the viewpoint of effectively imparting the adhesive force. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are preferably listed. The alkyl (meth) acrylates may be used alone or in combination of two or more.

Of the above-mentioned alkyl (meth) acrylates, it is preferable to use methyl (meth) acrylate and 2-ethylhexyl (meth) acrylate, particularly methyl methacrylate and 2-ethylhexyl acrylate, simultaneously. This makes it easy to obtain an adhesive having an excellent balance between adhesive force and pickup property. Preferably, the mass ratio is 5.

The acrylic copolymer (a) preferably contains 70% by mass or more, particularly preferably 75% by mass or more of the structural unit derived from the (meth) acrylate monomer. The acrylic copolymer (a) preferably contains not more than 97% by mass, particularly preferably not more than 90% by mass, of a structural unit derived from the (meth) acrylate monomer.

The acrylic copolymer (a) can be obtained by copolymerizing the functional group-containing monomer described above with a (meth) acrylic acid ester monomer or a derivative thereof by a conventional method, but dimethylacrylamide, vinyl acetate, styrene, and the like can be copolymerized in addition to these monomers.

The weight average molecular weight (Mw) of the acrylic copolymer (a) is preferably 30 ten thousand or more, particularly preferably 40 ten thousand or more, and more preferably 50 ten thousand or more. The weight average molecular weight (Mw) is preferably 150 ten thousand or less, particularly preferably 120 ten thousand or less, and further preferably 100 ten thousand or less. This makes it easy to obtain an adhesive having an excellent balance between adhesive force and pickup property. The weight average molecular weight (Mw) in the present specification is a value in terms of standard polystyrene measured by Gel Permeation Chromatography (GPC).

The crosslinking agent (B) may be reacted with a functional group of the acrylic copolymer (a), and examples thereof include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, hydrazine crosslinking agents, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, and ammonium salt crosslinking agents. The crosslinking agent (B) may be used singly or in combination of two or more.

When the acrylic copolymer (a) contains a hydroxyl group-containing monomer as a structural monomer unit, an isocyanate-based crosslinking agent having excellent reactivity with a hydroxyl group is preferably used as the crosslinking agent (B).

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound (polyisocynate). Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and biuret and isocyanurate derivatives thereof, and adducts thereof as reactants with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane and castor oil. Among them, trimethylolpropane-modified aromatic polyisocyanates are preferable from the viewpoint of reactivity with hydroxyl groups, and trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are particularly preferable.

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 further preferably 3 parts by mass or more, relative to 100 parts by mass of the acrylic copolymer (a). 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 further preferably 10 parts by mass or less, relative to 100 parts by mass of the acrylic copolymer (a). When the amount of the crosslinking agent (B) is in the above range, an adhesive having a predetermined adhesive force and a crosslinking density suitable for pickup properties can be obtained.

The thickness of the adhesive agent layer 12 of the present embodiment is preferably 1 μm or more, particularly preferably 3 μm or more, and more preferably 5 μm or more. The thickness of the adhesive layer 12 is preferably 50 μm or less, particularly preferably 30 μm or less, and more preferably 15 μm or less. By setting the thickness of the adhesive layer 12 in the above range, the balance between the adhesive force and the pickup property can be favorably achieved.

1-3. Release sheet

In the work processing sheet 1 of the present embodiment, for the purpose of protecting the surface of the adhesive agent layer 12 on the opposite side to the base material 11 (hereinafter, may be referred to as "adhesive surface"), a release sheet may be laminated on the surface before attaching the surface to the work.

The above-mentioned release sheet may be of any configuration, and examples thereof include a release sheet 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, silicones, fluorine-based ones, long-chain alkyl-based ones, and the like can be used, and among them, silicones which are inexpensive and can obtain stable performance are preferable.

The thickness of the release sheet is not particularly limited, and may be, for example, 16 μm or more and 250 μm or less.

1-4. Others

In the work processing sheet 1 of the present embodiment, a pressure-sensitive adhesive layer may be laminated on the surface of the pressure-sensitive adhesive layer 12 opposite to the substrate 11. In this case, the work processing sheet 1 of the present embodiment can be used as a dicing die bonding sheet. A work is attached to the surface of the adhesive layer of the sheet opposite to the adhesive layer 12, and the adhesive layer is cut together with the work, whereby a chip in which the singulated adhesive layers are stacked can be obtained. The singulated adhesive layer can be used to easily fix the chip to an object on which the chip is mounted. As a material constituting the pressure-sensitive adhesive layer, a material containing a thermoplastic resin and a low-molecular-weight thermosetting pressure-sensitive adhesive component, a material containing a B-stage (semi-cured) thermosetting pressure-sensitive adhesive component, or the like is preferably used.

In the work processing sheet 1 of 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 of the present embodiment can be used as a protective film forming and cutting sheet. A work is attached to the surface of the protective film forming layer of such a sheet opposite to the adhesive layer 12, and the protective film forming layer is cut together with the work, whereby a chip in which the protective film forming layers are individually stacked can be obtained. In this case, a protective film forming layer is generally laminated on the surface opposite to the surface on which the circuit is formed. By curing the singulated protective film forming layer at a predetermined time, a protective film having sufficient durability can be formed on the chip. Preferably, the protective film forming layer is formed of an uncured curable adhesive.

2. Method for manufacturing sheet for processing workpiece

The method for producing the workpiece-processing sheet 1 of the present embodiment is not particularly limited. For example, it is preferable to obtain the work processing sheet 1 by forming the adhesive layer 12 on the release sheet and then laminating the surface of the surface layer 111 side of the substrate 11 on the surface of the adhesive layer 12 opposite to the release sheet.

The adhesive layer 12 can be formed by a known method. For example, a coating liquid is prepared which contains an adhesive composition for forming the adhesive layer 12 and further contains a solvent or a dispersion medium as necessary. Then, the coating liquid is applied to a surface having releasability (hereinafter, sometimes referred to as "release surface") of the release sheet. Next, the obtained coating film is dried, whereby the adhesive layer 12 can be formed.

The coating liquid can be applied by a known method, for example, by a bar coating method, a doctor coating method (knife coating method), a roll coating method, a blade coating method (blade coating method), a die coating method (die coating method), a gravure coating method, or the like. The properties of the coating liquid are not particularly limited as long as the coating liquid can be applied, and a component for forming the adhesive agent layer 12 may be contained as a solute, or a component for forming the adhesive agent layer 12 may be contained as a dispersion. The release sheet can be released as a process material, and can protect the adhesive layer 12 until it is attached to an adherend.

When the adhesive composition for forming the adhesive agent layer 12 contains the crosslinking agent, it is preferable to form a crosslinked structure in the adhesive agent layer 12 at a desired existing density by causing a crosslinking reaction between the polymer component in the coating film and the crosslinking agent by changing the drying conditions (temperature, time, etc.) described above or by separately providing a heat treatment. Further, in order to sufficiently progress the crosslinking reaction, after the adhesive agent layer 12 and the substrate 11 are bonded, for example, aging may be performed by leaving them to stand for several days in an environment of 23 ℃ and a relative humidity of 50%.

3. Method for using sheet for processing workpiece

The workpiece processing sheet 1 of the present embodiment can be used for processing a workpiece such as a semiconductor wafer. That is, the adhesive surface of the workpiece processing sheet 1 of the present embodiment can be attached to a workpiece, and then the workpiece can be processed on the workpiece processing sheet 1. The work processing sheet 1 of the present embodiment can be used as a back grinding sheet, a dicing sheet, an expanding sheet, a picking sheet, and the like according to this processing. Here, as examples of the work, semiconductor members such as a semiconductor wafer and a semiconductor package; glass members such as glass plates.

As described above, the work processing sheet 1 of the present embodiment is excellent in the pickup property, and therefore is preferably a sheet used in a step including at least a pickup step. For example, the transfer sheet may be a dicing sheet used in the process from dicing to pickup, or may be a transfer sheet for pickup to which chips obtained by dicing are transferred.

Further, as described above, the sheet for processing a workpiece 1 of the present embodiment has excellent antistatic properties. The sheet 1 for processing a workpiece according to the present embodiment can suppress electrification upon separation of a release sheet or upon separation of a workpiece. Further, the work piece processing sheet 1 of the present embodiment can effectively suppress peeling electrification at the time of separating the work piece processing sheet from the rotary table after the chip is cleaned and dried in a state where the work piece processing sheet is fixed to the rotary table. Therefore, the work processing sheet 1 of the present embodiment can be suitably used for the above-described cleaning and drying.

When the work piece processing sheet 1 of the present embodiment includes the adhesive layer, the work piece processing sheet 1 can be used as a dicing/bonding sheet. In addition, when the work processing sheet 1 of the present embodiment includes the above-described protective film forming layer, the work processing sheet 1 can be used as a protective film forming and cutting sheet.

The embodiments described above are described for easy understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiments also covers all design changes and equivalents that fall within the technical scope of the present invention.

For example, another layer may be laminated between the base material 11 and the adhesive agent layer 12 of the work processing sheet 1 of the present embodiment, or on the surface of the base material 11 opposite to the adhesive agent layer 12. Further, other layers may be laminated on the surface of the front surface layer 111 opposite to the intermediate layer 112, between the front 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.

Examples

The present invention will be described in more detail with reference to examples and the like, but the scope of the present invention is not limited to these examples and the like.

[ example 1]

(1) Production of the substrate

28 parts by mass of a random Polypropylene resin (manufactured by Japan Polypropylene Corporation, product name "NOVATEC FX 3B"), 42 parts by mass of an olefin-based elastomer (manufactured by Japan Polypropylene Corporation, product name "WELNEX RFX 4V"), and 30 parts by mass of a polymer-based antistatic agent (SANYO CHEMICAL INDUSTRIES, manufactured by LTD., product name "PELECTRON PVH") were dried and kneaded by a biaxial kneader, thereby obtaining particles for a surface layer.

In addition, 38 parts by mass of an atactic Polypropylene resin (Japan Polypropylene resin)

Manufactured by Corporation, under the product name "novatex FX 3B"), and 62 parts by mass of an olefin-based elastomer (manufactured by Japan Polypropylene Corporation, under the product name "WELNEX RFX 4V"), were dried and then kneaded using a biaxial kneader, thereby obtaining particles for an intermediate layer.

65 parts by mass of an olefin elastomer (product name "WELNEX RFX4V" manufactured by Japan Polypropylene Corporation) and 35 parts by mass of a polymer type antistatic agent were added

(SANYO CHEMICAL INDUSTRIES, LTD., product name "PELECTRON PVH") was dried and kneaded with a two-shaft kneader, thereby obtaining pellets for the back surface layer.

Using the 3 kinds of pellets obtained as described above, a three-layer structured substrate was obtained by coextrusion molding using a small-sized T-die extruder (manufactured by Toyo Seiki Seisaku-sho, ltd., product name "LABO PLASTOMILL") to obtain a surface layer having a thickness of 4 μm, a middle layer having a thickness of 68 μm, and a back layer having a thickness of 4 μm, which were laminated in this order.

(2) Preparation of adhesive composition

A (meth) acrylate polymer was obtained by copolymerizing 78 parts by mass of 2-ethylhexyl acrylate, 12 parts by mass of methyl methacrylate, and 10 parts by mass of 2-hydroxyethyl acrylate by a solution polymerization method. The weight average molecular weight of the (meth) acrylate polymer was measured by the method described below, and found to be 80 ten thousand.

A coating solution of an adhesive composition was obtained by mixing 100 parts by mass (in terms of solid content, the same applies hereinafter) of the (meth) acrylate polymer obtained above and 4.7 parts by mass of trimethylolpropane-modified toluene diisocyanate (product name "CORONATE L", manufactured by TOSOH CORPORATION) as a crosslinking agent in a solvent.

(3) Formation of adhesive layer

Applying the coating liquid of the adhesive composition obtained in the step (2) to a coating film having a thickness of

The release surface of a release sheet (manufactured by linetec Corporation, product name "SP-PET 381031") having a silicone-based release agent layer formed on one surface of a 38 μm polyethylene terephthalate film was dried at 90 ℃ for 1 minute, thereby obtaining a laminate having an adhesive agent layer (a) formed on the release sheet to a thickness of 5 μm.

(4) Production of adhesive sheet

The surface of the substrate obtained in the step (1) on the surface layer side is subjected to corona treatment, and is bonded to the surface of the laminate obtained in the step (3) on the adhesive layer side, thereby obtaining a sheet for processing a workpiece.

Here, the weight average molecular weight (Mw) is a weight average molecular weight in terms of standard polystyrene measured by Gel Permeation Chromatography (GPC) under the following conditions (GPC measurement).

< measurement Condition >

The measurement device: HLC-8320, manufactured by TOSOH CORPORATION

GPC column (passage in the following order): TOSOH CORPORATION, inc

TSK gel superH-H

TSK gel superHM-H

TSK gel superH2000

Determination of the solvent: tetrahydrofuran (THF)

Measurement temperature: 40 deg.C

Examples 2 to 4 and comparative example 1

A sheet for workpiece processing was produced in the same manner as in example 1, except that the composition of particles for each layer forming the base material and the thickness of each layer were changed as described in table 1.

In example 2, 15 parts by mass of a styrene-based elastomer, styrene-ethylene/(ethylene-propylene) -styrene block copolymer (SEEPS) (KURARAY co., ltd., "HYBRAR 7311F", styrene ratio: 12 mass%) was blended in each of the surface layer, the intermediate layer, and the back layer.

In comparative example 1, 15 parts by mass of a maleic anhydride adduct of an ethylene-ethyl acrylate copolymer (SK Functional) as an acid-modified resin was further blended in the surface layer

Manufactured by Polymer company, product name "BONDINE LX4110", ethyl acrylate content: 5 mass%, acid component amount: 3% by mass).

[ example 5]

A substrate (same substrate as example 4) was produced in the same manner as in example 1, except that the composition of particles for forming each layer of the substrate 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 having an adhesive layer (b) with a thickness of 5 μm formed on a release sheet was obtained. Using the above-described base material and the laminate, a sheet for workpiece processing was produced in the same manner as in example 1.

[ example 6]

A substrate (same as the substrate of example 4) was produced in the same manner as in example 1, except that the composition of particles for forming each layer of the substrate 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) having a thickness of 5 μm was formed on a release sheet was obtained. Using the above-described base material and the laminate, a sheet for workpiece processing was produced in the same manner as in example 1.

Comparative example 2

Using the same apparatus as in example 1, a film formed of a single layer of ethylene-methacrylic acid copolymer (Dow-Mitsui Polychemicals co., ltd., product name "NUCREL N0903 HC") was produced. The surface of the obtained film on the side where the adhesive agent layer was laminated was irradiated once with an electron beam of 10kGy for 2.2 seconds to obtain a substrate. Using this base material, a sheet for workpiece processing was produced in the same manner as in example 1.

Comparative example 3

Using the same apparatus as in example 1, a film formed of a single layer of ethylene-methacrylic acid copolymer (manufactured by Dow-Mitsui polychemics co., ltd., product name "NUCREL N0903 HC") was produced. The surface of the obtained film on the adhesive layer-laminated side was irradiated with 10kGy of electron beam twice for 2.2 seconds each time, and the substrate was obtained. Using this base material, a sheet for workpiece processing was produced in the same manner as in example 1.

[ test example 1] (tensile test)

The substrates produced in examples and comparative examples were cut into test pieces of 10mm × 120mm, and the tensile stress at a temperature of 23 ℃ and a relative humidity of 50% RH was measured in accordance with JIS K7161: 2014. Specifically, the tensile stress (MPa) at 10%, 20% and 50% tensile elongation was measured by performing a tensile test on the test piece at a rate of 200 mm/min after setting the collet spacing to 100mm using a tensile tester (manufactured by Shimadzu Corporation, product name "AUTOGRAPH"). The extrusion direction (MD direction) of the base material during molding was measured. The results are shown in Table 2.

[ test example 2] (evaluation of pickup Property)

A silicon wafer ground to 150 μm with a grinder (product name "DFG8540" manufactured by DISCO Corporation) at #2000 was prepared.

After the release sheet was peeled from the work processing sheets manufactured in examples and comparative examples, the release sheet was peeled off, and the resultant was laminated on a film laminating machine (manufactured by linetec Corporation, product name "advill RAD2500 m/12"), the exposed surface of the exposed adhesive layer was attached to the polished surface of the silicon wafer. Next, a dicing ring frame is attached to a peripheral portion (a position not overlapping with a silicon wafer) of the exposed surface of the workpiece processing sheet. Further, the work processing sheet is cut according to the outer diameter of the ring frame.

Next, a cutting device (manufactured by DISCO Corporation, product name) was used

"DFD 6362"), silicon wafers were singulated into chips of 10mm × 10mm in size by dicing under the following dicing conditions.

< cutting Condition >

Thickness of the wafer: 150 μm

A blade: manufactured by DISCO Corporation, product name "ZH05-SD2000-N1-50 CC"

The rotating speed of the blade is as follows: 30000rpm

Cutting speed: 60 mm/sec

The depth of feed: 0.060mm

Cutting water amount: 1.0L/min

Cutting water temperature: 20 deg.C

A workpiece processing sheet was attached to a silicon wafer, and after 4 hours and 24 hours of attachment, chips were picked up from the workpiece processing sheet under the following pickup conditions using a pickup device (product name "beam D02" manufactured by Canon Machinery inc.). Then, the pin lift amount required for the pickup of the chip was measured. The results are shown in Table 2.

< pick-up Condition >

Picking mode: 4 pin

Pickup speed: 5mm/s

Pin jack-up amount: 550 to 800 mu m

Based on the pin lift amount measured above, the pickup was evaluated according to the following criteria.

The evaluation results are shown in table 2.

Good: the pin jacking amount is less than 600mm

X: the jacking amount of the pin exceeds 600mm

[ test example 3] (measurement of surface resistivity)

The work pieces produced in examples and comparative examples were cut into pieces of 100mm × 100mm, and the pieces were used as samples for measuring surface resistivity. The surface resistivity measurement sample was conditioned at a temperature of 23 ℃ and a relative humidity of 50% RH for 24 hours, and then the surface resistivity of the surface layer side (Ω/□) was measured at an applied voltage of 100V using a DIGITAL ELECTROMETER (ADVANTEST CORPORATION). The results are shown in Table 2.

[ test example 4] (evaluation of antistatic Property)

The work processing sheets produced in examples and comparative examples were cut into a B4 size, and the cut pieces were used as samples. The release sheet was peeled from the sample at a speed of 10 cm/s. The electrostatic voltage (V) of the sample just after completion of peeling was measured from the substrate side using an electrostatic Field tester (manufactured by Prostat Corporation, product name "Field Meter PFM-711A"). Then, the antistatic property was evaluated based on the following criteria. The electrostatic voltage and the evaluation results are shown in table 2.

O: static voltage of 1V or less

X: static voltage over 1V

As is clear from table 2, the sheets for processing workpieces produced in the examples were excellent in both the pickup property and the antistatic property.

Industrial applicability

The work processing sheet of the present invention can be suitably used for processing a work such as a semiconductor wafer.

Claims

1. A sheet for processing a workpiece, comprising a base material and an adhesive layer laminated on one surface side of the base material,

the substrate comprises a surface layer close to the adhesive layer, a back layer far from the adhesive layer, and an intermediate layer between the surface layer and the back layer,

the adhesive layer is formed of an adhesive curable with an inactive energy ray,

the surface layer and the back layer contain an antistatic agent,

a tensile stress of 8MPa or more and 30MPa or less when the substrate is subjected to a tensile test in an environment in which the relative humidity is 50% RH at a temperature of 23 ℃ and a tensile elongation of 20% and 50%.

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

3. The sheet for processing a workpiece according to claim 1, wherein the surface layer, the intermediate layer and the back layer each contain at least one of a polyolefin-based resin and an olefin-based thermoplastic elastomer.

4. The sheet for processing a workpiece according to claim 1,

the intermediate layer does not contain an antistatic agent, or

The intermediate layer contains an antistatic agent and is less than the respective contents of the antistatic agent in the surface layer and the back layer, the unit of the contents being mass%.

5. The sheet for processing a workpiece according to claim 1, wherein the antistatic agent is a polymer type antistatic agent.

6. The sheet for processing a workpiece according to claim 1, wherein the surface resistivity of the surface of the adhesive layer opposite to the base material is 1.0 x 10 ¹³ Omega/□ or less.

7. The sheet for processing a workpiece according to any of claims 1 to 6, which is a dicing sheet.