JP7688509B2 - Dicing sheet, dicing sheet manufacturing method, and semiconductor chip manufacturing method - Google Patents

Description

The present invention relates to a dicing sheet , a method for manufacturing a dicing sheet , and a method for manufacturing a semiconductor chip .

A dicing sheet used as a workpiece processing sheet is constructed with an adhesive layer on a base film, and is attached to a workpiece such as a semiconductor wafer using the adhesive layer, and is used in this state for dicing. After dicing, if necessary, the adhesive strength of the adhesive layer is reduced by curing it through exposure to energy rays such as ultraviolet light, and the processed workpiece such as a semiconductor chip is picked up. Dicing sheets with various configurations have been proposed so far depending on the purpose.

The adhesive layer of the dicing sheet typically uses an acrylic resin with energy ray-polymerizable unsaturated groups, and by irradiating the adhesive layer with energy rays such as ultraviolet (UV) rays, the adhesive strength with the adherend is reduced, making it easier to pick up the workpiece.

For example, Patent Document 1 discloses a semiconductor processing adhesive tape having an ultraviolet-curing adhesive layer on a polyvinyl chloride film. This semiconductor processing adhesive tape is capable of suppressing chipping and chipping during the dicing process, and can be easily peeled off during the pick-up process by reducing the adhesive strength to such an extent that no glue remains. It is also said that after the pick-up process is completed, the semiconductor processing adhesive tape can be overlapped and then easily peeled off separately.

Patent Document 2 also discloses a dicing film having an adhesive layer formed on the substrate, the adhesive layer containing an acrylic adhesive material and a photocurable resin. This dicing film has good adhesion between the adhesive layer and the substrate, and is said to be capable of easily picking up semiconductor chips and the like, and to prevent the adhesive layer from peeling off from the substrate and adhering to the back surface of the semiconductor chip during pick-up.

JP 2018-137376 A JP 2014-127609 A

However, the adhesive composition for forming the adhesive layer may not be able to ensure an appropriate pot life. In addition, there may be concerns about residues of the adhesive layer, i.e., particles, that are invisible to the naked eye, on workpieces such as semiconductor chips.

The present invention aims to provide a workpiece processing sheet in which the adhesive composition for forming the adhesive layer has an appropriate pot life and is less likely to contaminate wafers, as well as a method for manufacturing the workpiece processing sheet and a method for manufacturing a processed workpiece.

The present invention has the following aspects.
[1] A pressure-sensitive adhesive sheet comprising a base film and a pressure-sensitive adhesive layer provided on the base film,
The adhesive layer is a workpiece processing sheet formed using an energy ray-curable adhesive composition having as its components an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of acetylacetone zirconium complexes, metal soaps whose metal species is zirconium, and acetylacetone zinc complexes, and a crosslinking agent.
[2] A laminate of the workpiece processing sheet and the silicon wafer is produced by attaching the surface of the adhesive layer in the workpiece processing sheet opposite to the base film side to one surface of a silicon wafer,
The laminate was stored at room temperature and pressure for 24 hours immediately after its preparation.
The pressure-sensitive adhesive layer is irradiated with energy rays from the outside of the base film side of the laminate after the static storage, with the illuminance of the energy rays being 230 mW/ ^cm2 and the amount of light being 190 mJ/ ^cm2 , thereby curing the pressure-sensitive adhesive layer.
The cured product of the pressure-sensitive adhesive layer was peeled off from the silicon wafer together with the base film, and the number of particles adhering to the entire surface of one side of the silicon wafer after the cured product was peeled off was measured.
The workpiece processing sheet according to [1], wherein the number of particles is 1,000 or less.
[3] A method for producing a workpiece processing sheet according to [1] or [2],
reacting an acrylic resin having a hydroxyl group with a compound having an isocyanate group and an energy ray-polymerizable unsaturated group in the presence of the catalyst to form a urethane bond between the isocyanate group and a part of the hydroxyl group, thereby preparing an acrylic resin having the hydroxyl group and the energy ray-polymerizable unsaturated group;
preparing the energy ray-curable pressure-sensitive adhesive composition by blending the acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group with the crosslinking agent;
A method for producing a workpiece processing sheet, comprising providing the adhesive layer on the base film using the energy ray-curable adhesive composition, thereby producing the workpiece processing sheet.
[4] A method for manufacturing a workpiece using the workpiece processing sheet according to [1] or [2],
A step of attaching the surface of the adhesive layer in the work processing sheet opposite to the base film side to one surface of the work, thereby preparing a laminate of the work processing sheet and the work;
A step of processing the work in the laminate to produce a workpiece composite in which the workpiece is held by the adhesive layer in the workpiece processing sheet;
irradiating the pressure-sensitive adhesive layer with energy rays from the outside of the base film side of the workpiece composite to harden the pressure-sensitive adhesive layer;
and a step of separating and picking up the workpiece from the cured product of the adhesive layer.

According to the present invention, there are provided a workpiece processing sheet in which the adhesive composition for forming the adhesive layer has an appropriate pot life and is less likely to contaminate the wafer, a method for manufacturing the workpiece processing sheet, and a method for manufacturing a processed workpiece.

1 is a cross-sectional view showing a schematic diagram of one embodiment of a workpiece processing sheet of the present invention. FIG. 2 is a cross-sectional view showing a schematic diagram of another embodiment of the workpiece processing sheet of the present invention. 1 is a cross-sectional view showing a schematic diagram of one embodiment of a method for manufacturing a workpiece according to the present invention;

<<Work processing sheets>>

The workpiece processing sheet of the present invention will be described with reference to the drawings. Note that the drawings used in the following description may show the main parts enlarged for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

FIG. 1 is a cross-sectional view showing a schematic diagram of one embodiment of the workpiece processing sheet of the present invention.
The workpiece processing sheet 101 shown here comprises a base film 11 and an adhesive layer 12 provided on the base film 11 .

In the workpiece processing sheet 101, an adhesive layer 12 is laminated on one surface 11a (hereinafter sometimes referred to as the "first surface") of the base film 11.

The workpiece processing sheet 101 shown in FIG. 1 is used by attaching the first surface 12a of the adhesive layer 12 opposite the base film 11 to the surface of a workpiece (not shown) such as a semiconductor wafer, opposite the surface on which the circuit is formed.

Here, the term "workpiece" refers to a wafer or a semiconductor device panel.
Examples of the "wafer" include semiconductor wafers made of elemental semiconductors such as silicon, germanium, and selenium, and compound semiconductors such as GaAs, GaP, InP, CdTe, ZnSe, and SiC; and insulator wafers made of insulators such as sapphire and glass.
The term "semiconductor device panel" refers to an assembly of two or more semiconductor devices, each having one or more electronic components sealed with a sealing resin layer, arranged side by side in a plane.
A circuit is formed on one surface of each of these workpieces, and in this specification, the surface of the workpiece on which the circuit is formed is referred to as the "circuit surface," and the surface of the workpiece opposite to the circuit surface is referred to as the "rear surface."
The work is divided by means of dicing or the like to become workpieces. In this specification, as in the case of the work, the surface of the workpiece on which a circuit is formed is referred to as the "circuit side," and the surface of the workpiece opposite to the circuit side is referred to as the "rear side."
Both the circuit surface of the workpiece and the circuit surface of the workpiece are provided with protruding electrodes such as bumps, pillars, etc. The protruding electrodes are preferably made of solder.

In the workpiece processing sheet 101, the adhesive layer is formed using an energy ray curable adhesive composition containing as its components an acrylic resin having a hydroxyl group and an energy ray polymerizable unsaturated group, one or more catalysts selected from the group consisting of acetylacetone zirconium complexes, metal soaps whose metal species is zirconium, and acetylacetone zinc complexes, and a crosslinking agent.

When the workpiece processing sheet 101 is used to manufacture a workpiece such as a semiconductor chip, the adhesive layer in the workpiece processing sheet 101 is formed using an energy ray curable adhesive composition containing the catalyst and a crosslinking agent as blending components, so that when the adhesive layer is formed, the pot life of the adhesive composition can be made good.

The above catalysts are either metal complexes or metal soaps, which have the property of not generating static electricity and do not themselves become residues (i.e., particles), so it is believed that they can reduce contamination of the workpiece (i.e., the number of particles).

The workpiece processing sheet of the present invention preferably has a particle count of 1,000 or less, more preferably 800 or less, even more preferably 600 or less, and particularly preferably 350 or less, measured under the conditions of [Evaluation of wafer contamination] below.

[Evaluation of wafer contamination]
The side of the adhesive layer in the workpiece processing sheet opposite the base film side is attached to one side of a silicon wafer to produce a laminate of the workpiece processing sheet and the silicon wafer.
The laminate is stored at room temperature and pressure for 24 hours immediately after its preparation.
After the static storage, the pressure-sensitive adhesive layer is irradiated with energy rays from the outside of the base film side of the laminate at an illuminance of 230 mW/ ^cm2 and a light quantity of 190 mJ/ ^cm2 to cure the pressure-sensitive adhesive layer.
The cured product of the pressure-sensitive adhesive layer is peeled off from the silicon wafer together with the base film, and the number of particles adhering to the entire surface of one side of the silicon wafer after the cured product is peeled off is measured.

The energy beam can be irradiated using a commercially available ultraviolet ray irradiator, such as RAD2000 manufactured by Lintec Corporation.
The number of particles can be measured using a commercially available wafer surface inspection device, such as the WM-7S manufactured by Topcon Corporation.

Furthermore, the catalyst accelerates the reaction rate when the hydroxyl group of the hydroxyl group-containing compound reacts with the isocyanate group of the isocyanate group-containing compound to form a urethane bond.
Therefore, the catalyst accelerates the reaction rate when a urethane bond is formed by reacting a hydroxyl group of a hydroxyl group-containing copolymer with an isocyanate group of a compound having an isocyanate group and an energy ray-polymerizable unsaturated group, thereby synthesizing an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, and the catalyst accelerates the reaction rate when a urethane bond is formed by reacting a hydroxyl group of an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group with a crosslinker having an isocyanate group in an energy ray-curable pressure-sensitive adhesive composition.

However, the catalyst only has a moderate effect of promoting the reaction rate at room temperature. Therefore, when forming the adhesive layer using the energy ray-curable adhesive composition, the reaction between the hydroxyl groups of the acrylic resin and the crosslinking agent can be allowed to proceed slowly by selecting the catalyst, and the pot life of the energy ray-curable adhesive composition can be improved.

When the workpiece processing sheet 101 is viewed in plan from above the adhesive layer 12 side, the adhesive layer 12 has a shape such as a circle.

The workpiece processing sheet of the present invention is not limited to the workpiece processing sheet 101 shown in FIG. 1, and some of the configuration shown in FIG. 1 may be changed, deleted, or added within the scope that does not impair the effects of the present invention.

For example, the adhesive layer 12 may be one layer (single layer) or two or more layers. FIG. 2 is a cross-sectional view showing a schematic diagram of another embodiment of the work processing sheet of the present invention. The work processing sheet 101' shown here is a dicing sheet having an adhesive layer 12 on a base film 11. In FIG. 2 and subsequent figures, components that are the same as those shown in the figures already described are given the same reference numerals as in the figures already described, and detailed descriptions thereof are omitted.

In the workpiece processing sheet 101', an adhesive layer 12 is laminated on one surface (hereinafter sometimes referred to as the "first surface") 11a of the base film 11, and the adhesive layer 12 is composed of a first adhesive layer 121 on the side opposite the base film 11 and a second adhesive layer 122 on the base film 11 side, and the first adhesive layer 121 is formed using an energy ray curable adhesive composition containing the catalyst and a crosslinking agent as blending components.

The workpiece processing sheet 101' shown in FIG. 2 is used by attaching the first surface 12a of the adhesive layer 12 opposite the base film 11 to the back surface of a workpiece (not shown) such as a semiconductor wafer, opposite the circuit surface.

Below, we will explain each layer that makes up the dicing sheet as the workpiece processing sheet of the present invention.

[Base film]
The constituent material of the base film is preferably various resins, and specifically, for example, polyethylene (sometimes abbreviated as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE, etc.)), polypropylene, polybutene, polybutadiene, polymethylpentene, styrene-ethylenebutylene-styrene block copolymer, polyvinyl chloride, vinyl chloride copolymer, polyethylene terephthalate (sometimes abbreviated as PET), polybutylene terephthalate, polyurethane, polyurethane acrylate, polyimide, ethylene vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, polystyrene, polycarbonate, fluororesin, water additive, modified product, crosslinked product or copolymer of any of these resins, etc. are mentioned. From the viewpoint of cutting chip suppression and expandability, low density polyethylene (LDPE) film, ethylene-methacrylic acid (EMAA) copolymer film, ethylene-(meth)acrylate (EMMA) copolymer film are preferable.

In this specification, "(meth)acrylic acid" is a concept that includes both "acrylic acid" and "methacrylic acid." The same applies to terms similar to (meth)acrylic acid. For example, "(meth)acrylate" is a concept that includes both "acrylate" and "methacrylate," and "(meth)acryloyl group" is a concept that includes both "acryloyl group" and "methacryloyl group."

The resin constituting the base film may be one type or two or more types, and if there are two or more types, the combination and ratio of these can be selected arbitrarily.

The base film may be one layer (i.e., a single layer) or two or more layers. When the base film is made of multiple layers, these layers may be the same or different from each other. That is, all layers may be the same, all layers may be different, or only some layers may be the same. When the layers are different from each other, the combination of these layers is not particularly limited as long as it does not impair the effect of the present invention. Here, the layers being different from each other means that at least one of the material and thickness of each layer is different from each other.
In this specification, not only in the case of a base film, "multiple layers may be the same or different" means "all layers may be the same, all layers may be different, or only some layers may be the same", and further, "multiple layers are different" means "at least one of the constituent materials and thicknesses of each layer is different from each other".

The thickness of the substrate film can be appropriately selected depending on the purpose, but is preferably from 20 μm to 200 μm, more preferably from 25 μm to 150 μm, and particularly preferably from 30 μm to 100 μm.
Here, the "thickness of the base film" means the thickness of the entire base film, and for example, the thickness of a base film consisting of multiple layers means the total thickness of all layers constituting the base film. Note that, as a method for measuring the thickness of the base film, for example, a method of measuring the thickness at any five points using a contact thickness meter and calculating the average of the measured values can be mentioned.

In order to improve adhesion to other layers, such as a pressure-sensitive adhesive layer, provided thereon, the substrate film may be subjected to a surface treatment such as sandblasting, solvent treatment, embossing, or an oxidation treatment such as corona discharge treatment, electron beam irradiation treatment, plasma treatment, ozone/ultraviolet radiation treatment, flame treatment, chromic acid treatment, or hot air treatment.
The surface of the base film may be treated with a primer.
The base film may also have an antistatic coating layer, a layer that prevents the base film from adhering to other sheets or to an adsorption table when the film-like adhesive composite sheet is stacked and stored, and the like.
Of these, it is preferable for the substrate film to have its surface subjected to electron beam irradiation treatment in order to prevent the generation of fragments of the substrate film due to friction of the blade when dicing the workpiece, whereas it is preferable for the substrate film not to have been subjected to electron beam irradiation treatment in order to facilitate pick-up.

[Adhesive layer]
The pressure-sensitive adhesive layer is formed using an energy ray-curable pressure-sensitive adhesive composition containing as blending components an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of acetylacetone zirconium complexes, metal soaps whose metal species is zirconium, and acetylacetone zinc complexes, and a crosslinking agent.

The adhesive layer can be easily adjusted to an appropriate adhesive strength (β1) before UV irradiation, measured by the following measurement method, using an energy ray-curable adhesive composition.

[Method for measuring adhesive strength (β1) before UV irradiation]
After cutting the dicing sheet to a size of 25 mm in width and 150 mm in length, the release film is peeled off, and the exposed surface of the adhesive layer is attached to the mirror surface of a silicon wafer (diameter 6 inches, thickness 600 μm, silicon mirror wafer) at 23° C. and 50% relative humidity by moving a 2 kg roller back and forth once.
After 20 minutes, the 180° peel adhesion is measured in accordance with JIS Z 0237, and the measured value is regarded as the adhesion (β1) (mN/25 mm) before UV irradiation.

The pressure-sensitive adhesive layer preferably has an adhesive strength (β1) before the UV irradiation of 2000 mN/25 mm or more, more preferably 3000 mN/25 mm or more, and even more preferably 4000 mN/25 mm or more.
The pressure-sensitive adhesive layer preferably has an adhesive strength (β1) before the UV irradiation of 10,000 mN/25 mm or less, more preferably 8,000 mN/25 mm or less, and even more preferably 7,000 mN/25 mm or less.
The adhesive layer has an adhesive strength (β1) before UV irradiation that is equal to or greater than the lower limit, thereby preventing defective dicing of the workpiece. The adhesive layer has an adhesive strength (β1) before UV irradiation that is equal to or less than the upper limit, thereby making it easier to adjust the UV irradiation conditions.

The adhesive layer can be easily adjusted to an appropriate adhesive strength (β2) after UV irradiation, measured by the following measurement method, using an energy ray-curable adhesive composition.

[Method for measuring adhesive strength (β2) after UV irradiation]
After cutting the dicing sheet to a size of 25 mm in width and 150 mm in length, the release film is peeled off, and the exposed surface of the adhesive layer is attached to the mirror surface of a silicon wafer (diameter 6 inches, thickness 600 μm, silicon mirror wafer) at 23° C. and 50% relative humidity by moving a 2 kg roller back and forth once.
After 20 minutes, the pressure-sensitive adhesive layer is irradiated with ultraviolet (UV) rays from the outside of the base film side under conditions of an illuminance of 230 mW/ ^cm2 and a light quantity of 190 mJ/ ^cm2 , and then the 180° peel adhesive strength is measured in accordance with JIS Z 0237, and the measured value is regarded as the adhesive strength (β2) (mN/25 mm) after UV irradiation.

A commercially available ultraviolet irradiation device can be used for the ultraviolet (UV) irradiation. An example of a commercially available ultraviolet irradiation device is the RAD2000 manufactured by Lintec Corporation.

The adhesive layer preferably has an adhesive strength (β2) after the UV irradiation of 200 mN/25 mm or less, more preferably 180 mN/25 mm or less, and even more preferably 160 mN/25 mm or less.
The adhesive layer preferably has an adhesive strength (β2) after the UV irradiation of 10 mN/25 mm or more, more preferably 20 mN/25 mm or more, and even more preferably 30 mN/25 mm or more.
The adhesive layer has an adhesive strength (β2) after UV irradiation that is equal to or less than the upper limit, so that the workpiece can be picked up more easily. The adhesive layer has an adhesive strength (β2) after UV irradiation that is equal to or more than the lower limit, so that the workpiece can be prevented from being picked up poorly.

The thickness of the pressure-sensitive adhesive layer can be appropriately selected depending on the purpose, but is preferably 1 to 100 μm, more preferably 1 to 60 μm, and particularly preferably 1 to 30 μm.
Here, the "thickness of the adhesive layer" means the thickness of the entire adhesive layer, and for example, the thickness of an adhesive layer consisting of multiple layers means the total thickness of all layers constituting the adhesive layer. The thickness of the adhesive layer can be measured, for example, by measuring the thickness at any five points using a contact thickness meter and calculating the average of the measured values.

The adhesive layer can be formed using an adhesive composition containing various components for constituting the adhesive layer. The ratio of the contents of the components in the adhesive composition that do not vaporize at room temperature is usually the same as the ratio of the contents of the components in the adhesive layer. In this specification, "room temperature" means a temperature that is not particularly cooled or heated, that is, an ordinary temperature, and examples of such temperatures include temperatures of 15 to 30°C.

The adhesive layer contains an acrylic resin having an energy ray-polymerizable unsaturated group, so that the adhesive layer can be irradiated with energy rays to reduce its adhesiveness, making it easier to pick up the workpiece. The process of irradiating the adhesive layer with energy rays to reduce its adhesiveness may be performed after the workpiece processing sheet is attached to the adherend, or may be performed in advance before attaching the workpiece processing sheet to the adherend.

In the present invention, the term "energy ray" refers to electromagnetic waves or charged particle beams that have an energy quantum, and examples of such beams include ultraviolet rays and electron beams.
The ultraviolet light can be irradiated by using, for example, a UV-LED, a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, etc. as an ultraviolet light source. The electron beam can be generated by an electron beam accelerator or the like.
In the present invention, "energy ray curable" means a property of being cured by irradiation with energy rays, and "non-energy ray curable" means a property of not being cured even when irradiated with energy rays.

[Adhesive composition]
The energy ray-curable adhesive composition is a raw material for producing the adhesive layer, and contains as its components an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of an acetylacetone zirconium complex, a metal soap whose metal species is zirconium, and an acetylacetone zinc complex, and a crosslinking agent.
The acrylic resin in the pressure-sensitive adhesive composition is an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group.
In this specification, the energy ray-curable pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer may be simply referred to as an "adhesive composition." The term "acrylic resin" in the pressure-sensitive adhesive composition means "acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group," unless otherwise specified.

(Acrylic resin)
The acrylic resin having a hydroxyl group and an energy ray polymerizable unsaturated group can be, for example, a resin obtained by copolymerizing a (meth)acrylic acid ester not containing a hydroxyl group, a hydroxyl group-containing monomer, and, if necessary, a non-(meth)acrylic acid ester other than these, and reacting the hydroxyl group of the obtained acrylic resin having a hydroxyl group (hereinafter sometimes referred to as a "precopolymer") with the isocyanate group of a compound having an isocyanate group and an energy ray polymerizable unsaturated group to form a urethane bond. By making the molar amount of the isocyanate group in the compound having an isocyanate group and an energy ray polymerizable unsaturated group less than the molar amount of the hydroxyl group in the hydroxyl group-containing monomer, an acrylic resin having a hydroxyl group and an energy ray polymerizable unsaturated group can be obtained.
The acrylic resin has an energy ray polymerizable unsaturated group in the side chain, which improves the releasability from the adherend due to the reduced adhesiveness of the adhesive layer after the polymerization reaction (hardening), thereby improving the pick-up ability of the workpiece.

The (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (palmityl (meth)acrylate), heptadecyl (meth)acrylate, oct ... Examples include alkyl (meth)acrylates in which the alkyl group constituting the alkyl ester has a chain structure containing 1 to 18 carbon atoms, such as tadecyl (meth)acrylate (stearyl (meth)acrylate) and isooctadecyl (meth)acrylate (isostearyl (meth)acrylate); cycloalkyl (meth)acrylates such as isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; cycloalkenyl (meth)acrylates such as dicyclopentenyl (meth)acrylate; cycloalkenyloxyalkyl (meth)acrylates such as dicyclopentenyloxyethyl (meth)acrylate; imide (meth)acrylates; and glycidyl group-containing (meth)acrylates such as glycidyl (meth)acrylate.

Examples of the hydroxyl group-containing monomer include hydroxyl group-containing (meth)acrylates such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

Preferred examples of the non-(meth)acrylic acid ester include (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-methylolacrylamide.

The (meth)acrylic acid ester, the hydroxyl group-containing monomer, the non-(meth)acrylic acid ester, and other monomers constituting the acrylic resin may each be of one type or two or more types.

Examples of the compound having an isocyanate group and an energy ray-polymerizable unsaturated group include isocyanate group-containing (meth)acrylic acid esters such as 2-methacryloyloxyethyl isocyanate.
The compound having an isocyanate group and an energy ray-polymerizable unsaturated group constituting the acrylic resin may be of only one type or of two or more types.

The adhesive composition may contain only one type of acrylic resin, or two or more types.

The content of the acrylic resin in the adhesive composition is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total amount of all components contained in the adhesive composition other than the solvent. The content of the acrylic resin in the adhesive composition is preferably 99% by mass or less, more preferably 97% by mass or less, based on the total amount of all components contained in the adhesive composition other than the solvent.

(catalyst)
The catalyst is selected from the group consisting of acetylacetone zirconium complexes, metal soaps in which the metal species is zirconium, and acetylacetone zinc complexes.

Acetylacetone Zirconium Complex As the acetylacetone zirconium complex, a commercially available product such as zirconium (IV) acetylacetone can be used.

Metal Soap The metal soap contained in the pressure-sensitive adhesive composition is not limited as long as the metal species is zirconium. Examples of the metal soap include zirconium myristate, zirconium palmitate, zirconium stearate, zirconium oleate, zirconium laurate, zirconium ricinoleate, zirconium octylate, zirconium 2-ethylhexanoate, and fatty acid zirconium salts bonded to fatty acids such as zirconium oxide (2-ethylhexanoate).

The above metal soap may be one or more types. Commercially available metal soaps may be used.

The number of carbon atoms in the fatty acid of the fatty acid zirconium salt is preferably 5 to 20, more preferably 6 to 18, and particularly preferably 7 to 16.

Zinc Acetylacetone Complex As the zinc acetylacetone complex, commercially available zinc acetylacetonate (II) monohydrate can be used.

The content (blending amount) of the catalyst in the pressure-sensitive adhesive composition may be appropriately adjusted depending on the activity of the catalyst, but is preferably 0.001 to 1.5 parts by mass, more preferably 0.005 to 1.0 part by mass, and particularly preferably 0.01 to 0.5 parts by mass, relative to 100 parts by mass of the acrylic resin.
The catalyst content (blended amount) of the pressure-sensitive adhesive composition is preferably 0.001 to 1.5 parts by mass, more preferably 0.005 to 1.0 part by mass, and particularly preferably 0.01 to 0.5 parts by mass, relative to 100 parts by mass of the precopolymer.

(Crosslinking Agent)
The crosslinking agent is not limited as long as it is a crosslinking agent used in a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer, and examples thereof include organic polyvalent isocyanate compounds.

Examples of the organic polyisocyanate compound include aromatic polyisocyanate compounds, aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, and trimers, isocyanurates, and adducts of these compounds, as well as terminal isocyanate urethane prepolymers obtained by reacting the aromatic polyisocyanate compounds, aliphatic polyisocyanate compounds, or alicyclic polyisocyanate compounds with polyol compounds. The adducts refer to the reaction products of the aromatic polyisocyanate compounds, aliphatic polyisocyanate compounds, or alicyclic polyisocyanate compounds with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, or castor oil.

Specific examples of the organic polyisocyanate compound include 2,4-tolylene diisocyanate; 2,6-tolylene diisocyanate; 1,3-xylylene diisocyanate; 1,4-xylylene diisocyanate; diphenylmethane-4,4'-diisocyanate; diphenylmethane-2,4'-diisocyanate; 3-methyldiphenylmethane diisocyanate; hexamethylene diisocyanate; isophorone diisocyanate; dicyclohexylmethane-4,4'-diisocyanate; dicyclohexylmethane-2,4'-diisocyanate; a compound in which either or both of tolylene diisocyanate and hexamethylene diisocyanate are added to all or some of the hydroxyl groups of a polyol such as trimethylolpropane; lysine diisocyanate, etc.

When the crosslinking agent has an isocyanate group, a crosslinked structure can be easily introduced into the adhesive layer by the reaction between the isocyanate group and a hydroxyl group.

The adhesive composition may contain only one type of crosslinking agent, or two or more types.

When a crosslinking agent is used, the content of the crosslinking agent in the pressure-sensitive adhesive composition is preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 16 parts by mass, per 100 parts by mass of the acrylic polymer.

(Photopolymerization initiator)
The pressure-sensitive adhesive composition preferably contains a photopolymerization initiator in addition to the acrylic resin, the catalyst, and the crosslinking agent.
The photopolymerization initiator may be a known one, and specifically, examples of the photopolymerization initiator include α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexyl phenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and ketal compounds such as benzyl dimethyl ketal. aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; and acylphosphonates.

The pressure-sensitive adhesive composition may contain only one type of photopolymerization initiator, or two or more types.

When a photopolymerization initiator is used, the content of the photopolymerization initiator in the adhesive composition is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, relative to 100 parts by mass of the acrylic resin. When the content of the photopolymerization initiator is equal to or greater than the lower limit, the effect of using the photopolymerization initiator can be sufficiently obtained. Furthermore, when the content of the photopolymerization initiator is equal to or less than the upper limit, precipitation of the photopolymerization initiator and the generation of by-products from excess photopolymerization initiator are suppressed, and the curing of the adhesive layer proceeds more smoothly.

(solvent)
The pressure-sensitive adhesive composition preferably further contains a solvent in addition to the acrylic resin, the catalyst, and the crosslinking agent.
The solvent is not particularly limited, but preferred examples include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutyl alcohol (2-methylpropan-1-ol), and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; and amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone.
The pressure-sensitive adhesive composition may contain only one type of solvent, or two or more types of solvents.

When the adhesive composition contains a solvent, the solvent content is preferably 40 to 90% by mass, and more preferably 50 to 80% by mass.

(Other ingredients)
The pressure-sensitive adhesive composition may contain, in addition to the acrylic resin and crosslinking agent, other components that do not fall under the category of a photopolymerization initiator and a solvent, as long as the effects of the present invention are not impaired.
The other components may be known ones and may be arbitrarily selected depending on the purpose, and are not particularly limited. Preferred examples of the other components include various additives such as dyes, pigments, antidegradants, antistatic agents, flame retardants, silicone compounds, and chain transfer agents.
The pressure-sensitive adhesive composition may contain only one type of other component, or two or more types of such other components.

The pressure-sensitive adhesive composition is obtained by blending an acrylic resin with a component other than the acrylic resin.
The order of addition of the components is not particularly limited, and two or more components may be added simultaneously.
For example, the energy ray-curable pressure-sensitive adhesive composition can be obtained by preparing a reaction product containing an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, and blending the reaction product with the crosslinking agent.
The method for mixing the components during blending is not particularly limited, and may be appropriately selected from known methods such as a method of mixing by rotating a stirrer or stirring blade, a method of mixing using a mixer, a method of mixing by applying ultrasound, etc.
The temperature and time during addition and mixing of each component are not particularly limited as long as the components do not deteriorate, and may be adjusted appropriately. The temperature is preferably 15 to 30°C.

The adhesive layer may be formed by adjusting, for example, the number of energy ray polymerizable unsaturated groups such as (meth)acryloyl groups contained in each component such as the acrylic resin blended into the adhesive composition, the type and amount of crosslinking agent, the type of monomer constituting the acrylic resin, the type and amount of catalyst, etc., so that the elastic modulus after curing by energy ray irradiation falls within a predetermined range.

The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive composition to the surface of the base film and drying it.
At this time, if necessary, the applied pressure-sensitive adhesive composition may be heated for crosslinking. The heating conditions may be, for example, but are not limited to, 100 to 130° C. for 1 to 5 minutes.
Alternatively, the adhesive layer can be formed on the base film by applying the adhesive composition to the release-treated surface of a release film, drying the adhesive composition to form an adhesive layer, bonding the resulting adhesive layer to the surface of the base film, and removing the release film as necessary.

The adhesive composition may be applied to the surface of the substrate film or the release layer surface of the release material by a known method, such as a method using various coaters, such as an air knife coater, blade coater, bar coater, gravure coater, roll coater, roll knife coater, curtain coater, die coater, knife coater, screen coater, Mayer bar coater, or kiss coater.

<Release film>
The release film is not particularly limited, and commercially available release films can be used, such as polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate copolymer film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Crosslinked films of these films can also be used. Furthermore, laminated films of these films can also be used.

The surface tension of the release film on the surface in contact with the adhesive layer is preferably 40 mN/m or less, more preferably 37 mN/m or less, and particularly preferably 35 mN/m or less. The lower limit is usually about 25 mN/m. A release film with such a relatively low surface tension can be obtained by appropriately selecting the material, or by applying a release agent to the surface of the release film and carrying out a release treatment.

The release agents used in the peeling process include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, wax-based, and rubber-based agents, but alkyd-based, silicone-based, and fluorine-based release agents are particularly preferred because they are heat resistant.

To use the above release agents to perform a release treatment on the surface of a film or other substrate for the release film, the release agent can be applied directly without solvent, or diluted with a solvent or made into an emulsion, using a gravure coater, Mayer bar coater, air knife coater, roll coater, or the like, and the release film to which the release agent has been applied can be left at room temperature or under heat, or cured with an electron beam to form a release agent layer.

The surface roughness (Ra) of the release film is preferably 10 to 100 nm, more preferably 15 to 60 nm, and even more preferably 20 to 50 nm.

<<Method of manufacturing workpiece processing sheet>>
The method for producing a workpiece processing sheet of the present invention comprises a base film and an adhesive layer provided on the base film,
reacting an acrylic resin having a hydroxyl group with a compound having an isocyanate group and an energy ray-polymerizable unsaturated group in the presence of the catalyst to form a urethane bond between the isocyanate group and a part of the hydroxyl group, thereby preparing an acrylic resin having the hydroxyl group and the energy ray-polymerizable unsaturated group;
preparing the energy ray-curable pressure-sensitive adhesive composition by blending the acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group with the crosslinking agent;
The workpiece processing sheet is produced by providing the adhesive layer on the base film using the energy ray-curable adhesive composition.

For example, the above-mentioned adhesive composition can be applied to the release-treated surface of a release film, and dried as necessary to form an adhesive layer on the release film. The adhesive layer and base film can then be attached to produce a workpiece processing sheet in which the base film, adhesive layer, and release film are laminated in that order. The release film can be removed as necessary when using the workpiece processing sheet.

<<Method of manufacturing workpiece>>
The method for manufacturing a workpiece according to the present invention is a method for manufacturing a workpiece using the workpiece processing sheet,
A step of attaching the surface of the adhesive layer in the work processing sheet opposite to the base film side to one surface of the work, thereby preparing a laminate of the work processing sheet and the work;
A step of processing the work in the laminate to produce a workpiece composite in which the workpiece is held by the adhesive layer in the workpiece processing sheet;
irradiating the pressure-sensitive adhesive layer with energy rays from the outside of the base film side of the workpiece composite to harden the pressure-sensitive adhesive layer;
and a step of picking up the workpiece by separating it from the cured product of the adhesive layer.

For example, Figure 3 is a cross-sectional view showing a schematic embodiment of the method for manufacturing a workpiece of the present invention. In this embodiment of the method for manufacturing a workpiece, a workpiece processing sheet 101 includes a base film 11 and an adhesive layer 12 provided on the base film 11. The method for manufacturing the workpiece of this embodiment includes the steps of: (a) attaching the surface 12a of the adhesive layer 12 in the workpiece processing sheet 101 opposite the base film 11 side to one surface 9b of the workpiece 9 to produce a laminate of the workpiece processing sheet 101 and the workpiece 9; (b) processing the workpiece 9 in the laminate to produce a workpiece processing composite in which the workpiece processing product 9' is held by the adhesive layer 12 in the workpiece processing sheet 101; (c) irradiating the adhesive layer 12 with energy rays from the outside of the base film 11 side of the workpiece processing composite to harden the adhesive layer 12; and (d) using a peeling means 7 to peel off and pick up the workpiece processing product 9' from the hardened adhesive layer 12, as shown in FIG. 3(c).

The workpiece processing sheet of the present invention can also be used as a dicing die bonding sheet combined with a film-like adhesive for bonding a semiconductor element to a lead frame, an organic substrate, etc. It can also be used as a composite sheet for forming a back surface protective film combined with a protective film forming film for protecting the back surface of a workpiece of a semiconductor device.

The present invention will be explained in more detail below using examples of dicing sheets as workpiece processing sheets. However, the present invention is not limited to the examples shown below.

[Example 1]
(Production of acrylic resin)
Under a nitrogen atmosphere, 62 parts by mass of butyl acrylate (BA), 10 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (HEA) were reacted in the presence of 0.25 parts by mass of 0.1% azobisisobutyronitrile (polymerization initiator) in a reaction apparatus equipped with a stirrer, a condenser, a thermometer, and a nitrogen inlet tube at 60°C for 24 hours to obtain an ethyl acetate solution of a precopolymer (250 parts by mass, solid content concentration 40% by mass). Methyl ethyl ketone was added to the precopolymer, and the mixture was stirred with 0.012 parts by mass of Zr(C ₅ H ₇ O ₂ ) ₄ (product name: Nursem (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) at 50°C (MOI addition reaction temperature) for 1 hour to prepare a solution with a solid content concentration of 35% by mass. Thereafter, 30 parts by mass (an amount such that isocyanate groups account for 80 mol % relative to 100 mol % of hydroxyl groups in the HEA) of 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate, hereinafter sometimes abbreviated as "MOI") was added and reacted at 50°C for 48 hours (MOI addition reaction) to obtain a reaction product containing an acrylic resin having hydroxyl groups and energy ray-polymerizable unsaturated groups. The molecular weight of the obtained acrylic resin was measured, and the weight average molecular weight was found to be 500,000.

(Production of Pressure-Sensitive Adhesive Composition)
In 100 parts by mass (solid content) of the obtained acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, 3 parts by mass of "OMNILAD 184 (solid content 100 mass%)" manufactured by BASF as a photopolymerization initiator and 2.85 parts by mass (2.175 parts by mass in dry equivalent) of tolylene diisocyanate-based (TDI-based) polyisocyanate crosslinking agent "product name: CORONATE (registered trademark) L (solid content 75 mass%) manufactured by Tosoh Corporation" were dissolved to adjust the solid content concentration to 30 mass%, thereby preparing an energy ray-curable pressure-sensitive adhesive composition.

(Manufacturing of dicing sheets)
A release film (SP-PET3801, manufactured by Lintec Corporation) was prepared by treating one side of a polyethylene terephthalate (PET) film (thickness: 38 μm) with a light release type silicone resin, and the pressure-sensitive adhesive composition was applied to the release-treated surface using a comma coater. The adhesive composition was then dried at 90° C. for 1 minute to form a pressure-sensitive adhesive layer having a thickness of 5 μm.

After corona irradiation was performed on one side of an 80 μm thick ethylene-methacrylic acid (EMAA) copolymer film, the exposed surface of the adhesive layer was attached and stored at 23°C and 50% relative humidity for one week to obtain a dicing sheet of Example 1, which is composed of a base film, an adhesive layer, and a release film laminated in this order in the thickness direction.

[Example 2]
A dicing sheet of Example 2 was obtained in the same manner as in Example 1, except that 0.012 parts by mass of Zr(C ₅ H ₇ O ₂ ) ₄ (product name: Nursem (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) used in the adhesive composition in Example 1 was changed to 0.12 parts by mass of ZrO(C ₈ H ₁₅ O ₂ ) ₂ (2-ethylhexanoic acid) zirconium oxide (IV), manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), and the MOI addition reaction was changed to 45° C. for 48 hours to prepare a reaction product containing an acrylic resin. When the molecular weight of the acrylic resin in Example 2 was measured, the weight average molecular weight was 500,000.

[Example 3]
In Example 1, 0.012 parts by mass _{of Zr(C5H7O2 ) 4 (} trade name: Nacem (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) used in the adhesive composition was changed to 0.100 parts by mass _of Zn _{(C5H7O2 ) 2.H2O} (trade name: zinc acetylacetonate (II) monohydrate, manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), _and the MOI addition reaction was changed to 60°C for 48 hours to prepare a reaction product containing an acrylic resin. The dicing sheet of Example 3 was obtained in the same manner as in Example 1. When the molecular weight of the acrylic resin in Example 3 was measured, the weight average molecular weight was 500,000.

[Comparative Example 1]
_A dicing sheet of Comparative Example 1 was obtained in the same manner as in Example 1, except that 0.012 parts by mass of Zr(C ₅ H _{7 O 2} ) ₄ (product name: Narcem (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) used in the adhesive composition in Example 1 was changed to 0.140 parts by mass of (C 11 H 23 COO) ₂ Sn(C ₄ H ₉ ) ₂ (di-n-butyltin dilaurate, -) to prepare a reaction product containing an acrylic resin. When the molecular weight of the acrylic resin in Comparative Example 1 was measured, the weight average molecular weight was 500,000.

[Comparative Example 2]
_A dicing sheet of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the amount of _{( C11H23COO} ) _2Sn ( _C4H9 ) ₂ (di-n-butyltin dilaurate, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) used in the pressure-sensitive adhesive composition in Comparative Example 1 was changed from 0.140 parts by mass to 0.30 parts by mass, and the reaction time was changed from 48 hours at 50°C to 48 hours at 45°C, to prepare a reaction product containing an acrylic resin. When the molecular weight of the acrylic resin in Comparative Example 2 was measured, the weight average molecular weight was 500,000.

[Comparative Example 3]
In Example 1, 0.012 parts by mass _of Zr _{( C5H7O2} ) ₄ (trade name: Nacem (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) used in the adhesive composition was changed to 1.900 parts by mass of Zn _{( C8H15O2} ) ₂ (Zinc octoate, manufactured by Kishida Chemical Co., Ltd.), and the MOI addition reaction was changed to 60°C for 48 hours to prepare a reaction product containing an acrylic resin. A dicing sheet _of Comparative Example 3 was obtained in the same manner as in Example 1. When the molecular weight of the acrylic resin in Example 2 was measured, the weight average molecular weight was 500,000.

[Comparative Example 4]
In Example 1, 0.012 parts by mass _of Zr _{( C5H7O2} ) ₄ (trade name: NASEM (registered trademark) zirconium compound, manufactured by Nippon Chemical Industry Co., Ltd.) used in the adhesive composition was changed to 0.050 parts by mass _{of V} ( _C5H7O2 ) ₃ (vanadium acetylacetone (III), manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) to prepare a reaction product containing an acrylic resin. The same procedure as in Example 1 was repeated to obtain 7 dicing sheets of Comparative Example 3. When the molecular weight of the acrylic resin in Example 2 was measured, the weight average molecular weight was 500,000.

[Pot life evaluation]
The viscosity of the adhesive composition immediately after preparation when producing the dicing sheets of Examples 1 to 3 and Comparative Examples 1 to 4 was measured using a B-type viscometer. Thereafter, the adhesive composition was stored in an environment of 23° C., and the viscosity of the adhesive composition was measured every hour up to 12 hours using the B-type viscometer.
The time required for the viscosity to increase to 1.5 times the viscosity immediately after preparation was defined as the pot life of the pressure-sensitive adhesive composition. The evaluation results are shown in Tables 1 and 2.

[Measurement of adhesive strength (β1) before UV irradiation]
The dicing sheets of Examples 1 to 4 and Comparative Examples 1 to 4 were cut to a size of 25 mm wide and 150 mm long, and the release film was peeled off. The exposed surface of the adhesive layer was attached to the mirror surface of a silicon wafer (diameter 6 inches, thickness 600 μm, silicon mirror wafer) at 23° C. and 50% relative humidity, and the sheet was attached by rolling a 2 kg roller back and forth once. After 20 minutes, the 180° peel adhesion was measured according to JIS Z 0237, and the measured value was taken as the adhesion (β1) (mN/25 mm) before UV irradiation. The evaluation results are shown in Tables 1 and 2.

[Measurement of adhesive strength (β2) after UV irradiation]
The dicing sheets of Examples 1 to 4 and Comparative Examples 1 to 4 were cut to a size of 25 mm wide and 150 mm long, and the release film was peeled off. The exposed surface of the adhesive layer was attached to the mirror surface of a silicon wafer (diameter 6 inches, thickness 600 μm, silicon mirror wafer) at 23° C. and 50% relative humidity, and the adhesive layer was attached by moving a 2 kg roller back and forth once. After 20 minutes, the adhesive layer was irradiated with ultraviolet light (UV) from the outside of the base film side using an ultraviolet irradiation device (manufactured by Lintec Corporation, RAD2000) under conditions of an illuminance of 230 mW/cm ² and a light amount of 190 mJ/cm ² , and then the 180° peel adhesive strength was measured according to JIS Z 0237, and the measured value was taken as the adhesive strength (β2) (mN/25 mm) after UV irradiation. The evaluation results are shown in Tables 1 to 2.

[Evaluation of wafer contamination]
The release film was peeled off from the dicing sheets of Examples 1 to 3 and Comparative Examples 1 to 4, and the exposed surface of the adhesive layer was attached to the mirror surface of a silicon wafer (diameter 6 inches, thickness 600 μm, silicon mirror wafer), and a load was applied by moving a 5 kg roller back and forth once to laminate the sheets, thereby producing a laminate of the dicing sheet and the silicon wafer.
Immediately after preparation, the laminate was left to stand at 23° C. and 50% relative humidity for 24 hours.
Using an ultraviolet irradiation device (RAD2000, manufactured by Lintec Corporation), the pressure-sensitive adhesive layer was irradiated with ultraviolet (UV) rays from the outside of the base film side of the laminate after the static storage under conditions of an illuminance of 230 mW/ ^cm2 and a light quantity of 190 mJ/ ^cm2 to harden the pressure-sensitive adhesive layer.
The cured adhesive layer was peeled off and removed from the silicon wafer together with the base film at a peeling speed of 300 mm/min and a peeling angle of 180°. Thereafter, the number of particles with a maximum diameter of 0.27 μm or more and 5 μm or less on the silicon wafer was measured using a wafer surface inspection device (WM-7S, manufactured by Topcon Corporation). The evaluation results are shown in Tables 1 and 2.

As shown in Tables 1 and 2, in the dicing sheets of Examples 1 to 3, the adhesive layer is formed using an energy ray curable adhesive composition containing an acrylic resin having a hydroxyl group and an energy ray polymerizable unsaturated group, one or more catalysts selected from the group consisting of acetylacetone zirconium complex, metal soap whose metal type is zirconium, and acetylacetone zinc complex, and a crosslinking agent as blending components, so that the adhesive composition for forming the adhesive layer has an appropriate pot life and is less likely to contaminate the wafer. Since the adhesive strength (β1) before ultraviolet (UV) irradiation is large, it is excellent in suppressing chip flying during dicing of the semiconductor wafer, and since the adhesive strength (β2) after ultraviolet (UV) irradiation is small, it is easy to pick up the workpiece.

In the dicing sheet of Comparative Example 1, which used a tin-based catalyst, the pot life of the adhesive composition for forming the adhesive layer was short, so an appropriate pot life could not be ensured. In the dicing sheet of Comparative Example 2, an attempt was made to reduce the amount of tin-based catalyst to the amount thought to be the minimum necessary to synthesize an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, but the pot life of the adhesive composition was not sufficient.

The dicing sheet of Comparative Example 3, which used Zn(C ₈ H ₁₅ O ₂ ) ₂ as a catalyst, ensured an appropriate pot life, but the contamination of the wafer with particles was significant.

In the dicing sheet of Comparative Example 4 using V( _C5H7O2 ) ₃ ( _vanadium (III ₎ acetylacetonate) as a catalyst, the pot life of the adhesive composition was short, so an appropriate pot life could not be ensured. The adhesive strength (β1) before ultraviolet (UV) irradiation was insufficient, so there was a risk of chips flying off during dicing of the semiconductor wafer, and the adhesive strength (β2) after ultraviolet (UV) irradiation was also large, so there was a risk of poor pick-up of the workpiece.

The workpiece processing sheet of the present invention can be used to process workpieces such as semiconductor wafers.

101, 101': Workpiece processing sheet (dicing sheet), 11: Base film, 11a: First surface of base film, 12: Adhesive layer, 12a: First surface of adhesive layer, 13: Release film, 7: Peeling means, 9: Workpiece, 9a: Circuit surface of workpiece, 9b: Back surface of workpiece, 9': Workpiece processed product, 9a': Circuit surface of workpiece processed product

Claims (4)

A dicing sheet comprising a base film and an adhesive layer provided on the base film, the dicing sheet being attached to a semiconductor wafer by the adhesive layer and used for dicing in this state,
The dicing sheet, wherein the adhesive layer is formed using an energy ray-curable adhesive composition having as its components an acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group, one or more catalysts selected from the group consisting of acetylacetone zirconium complexes and metal soaps whose metal species is zirconium, and a crosslinking agent . a surface of the pressure-sensitive adhesive layer in the dicing sheet opposite to the base film side is attached to one surface of a silicon wafer, thereby producing a laminate of the dicing sheet and the silicon wafer;
The laminate was stored at room temperature and pressure for 24 hours immediately after its preparation.
The pressure-sensitive adhesive layer is irradiated with energy rays from the outside of the base film side of the laminate after the static storage, with the illuminance of the energy rays being 230 mW/ ^cm2 and the amount of light being 190 mJ/ ^cm2 , thereby curing the pressure-sensitive adhesive layer.
The cured product of the pressure-sensitive adhesive layer was peeled off from the silicon wafer together with the base film, and the number of particles adhering to the entire surface of one side of the silicon wafer after the cured product was peeled off was measured.
The dicing sheet according to claim 1 , wherein the number of the particles is 1000 or less. A method for producing the dicing sheet according to claim 1 or 2,
reacting an acrylic resin having a hydroxyl group with a compound having an isocyanate group and an energy ray-polymerizable unsaturated group in the presence of the catalyst to form a urethane bond between the isocyanate group and a part of the hydroxyl group, thereby preparing an acrylic resin having the hydroxyl group and the energy ray-polymerizable unsaturated group;
preparing the energy ray-curable pressure-sensitive adhesive composition by blending the acrylic resin having a hydroxyl group and an energy ray-polymerizable unsaturated group with the crosslinking agent;
a pressure-sensitive adhesive layer formed on the substrate film using the energy ray-curable pressure-sensitive adhesive composition, thereby producing the dicing sheet ; A method for manufacturing a semiconductor chip using the dicing sheet according to claim 1 or 2,
a step of attaching a surface of the pressure-sensitive adhesive layer in the dicing sheet opposite to the base film side to one surface of a semiconductor wafer , thereby producing a laminate of the dicing sheet and the semiconductor wafer ;
A step of dicing the semiconductor wafer in the laminate to produce a workpiece composite in which the semiconductor chip is held by the adhesive layer in the dicing sheet ;
irradiating the pressure-sensitive adhesive layer with energy rays from the outside of the base film side of the workpiece composite to harden the pressure-sensitive adhesive layer;
and picking up the semiconductor chip by detaching it from the cured product of the pressure-sensitive adhesive layer.

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