JP7675533B2 - Workpiece processing sheet - Google Patents

Description

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

Semiconductor wafers such as silicon and gallium arsenide and various packages are manufactured in a large diameter state, cut (diced) into chips, peeled off (picked up), and then moved to the next process, the mounting process. At this time, the workpieces such as semiconductor wafers are stacked on an adhesive sheet (hereinafter sometimes referred to as the "workpiece processing sheet") that has a base material and an adhesive layer, and are then processed, such as backgrinding, dicing, cleaning, drying, expanding, picking up, and mounting.

In the above-mentioned pick-up process, the chips obtained by dicing are usually individually separated from the workpiece processing sheet by a suction collet or the like. At this time, to facilitate this separation, the chips are pushed up by a pin or needle from the side of the workpiece processing sheet opposite the side on which the chips are stacked.

In some cases, the collection of chips obtained by dicing on the workpiece processing sheet is transferred to another workpiece processing sheet (pickup sheet), and then the pick-up process is carried out on the pick-up sheet.

During the above pickup or transfer, the adhesive layer may peel off from the base material constituting the workpiece processing sheet, causing the adhesive constituting the adhesive layer to adhere to the chip (residual adhesive). This type of residual adhesive tends to occur particularly easily when the base material is primarily made of vinyl chloride resin. If the chip is incorporated into a product with the adhesive still attached, this has a significant adverse effect on the performance of the product, so there is a demand to suppress the occurrence of residual adhesive.

With the aim of suppressing the occurrence of the above-mentioned adhesive residue, Patent Document 1 discloses an adhesive tape for semiconductor processing that has a specified adhesive layer on a polyvinyl chloride film. In addition, Patent Document 2 discloses an adhesive tape for semiconductor wafer processing that has a specified adhesive applied to a specified soft polyvinyl chloride resin film substrate.

JP 2018-137376 A JP 2006-36834 A

However, even if conventional workpiece processing sheets such as those disclosed in Patent Documents 1 and 2 are used, the problem of glue residue cannot be fully solved. Therefore, there is a need to develop a workpiece processing sheet that can further suppress the occurrence of glue residue.

The present invention was made in consideration of these circumstances, and aims to provide a work processing sheet that effectively prevents glue residue from occurring.

In order to achieve the above object, first, the present invention provides a work processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, the substrate comprising a resin layer formed from a resin composition containing a vinyl chloride resin and a stabilizer, the stabilizer comprising at least one of a saturated fatty acid metal salt having 12 or more and less than 18 carbon atoms and an unsaturated fatty acid metal salt having 12 or more and less than 20 carbon atoms (Invention 1).

The work processing sheet according to the above invention (Invention 1) contains a resin composition for forming the base material that contains a saturated fatty acid metal salt or an unsaturated fatty acid metal salt having the above-mentioned carbon number as a stabilizer, so that even though the base material is mainly made of vinyl chloride resin, the occurrence of residual glue can be effectively suppressed.

In the above invention (Invention 1), the content of the stabilizer in the resin composition is preferably 0.01 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the vinyl chloride resin (Invention 2).

In the above inventions (Inventions 1 and 2), it is preferable that the resin composition contains a plasticizer (Invention 3).

In the above inventions (Inventions 1 to 3), it is preferable that the substrate consists of a single resin layer (Invention 4).

In the above inventions (Inventions 1 to 3), it is preferable that the substrate is made of multiple layers, at least one of which is the resin layer (Invention 5).

In the above inventions (Inventions 1 to 5), it is preferable that the adhesive layer is composed of an active energy ray-curable adhesive (Invention 6).

In the above inventions (Inventions 1 to 6), it is preferable that the sheet is a dicing sheet (Invention 7).

The workpiece processing sheet of the present invention can effectively prevent glue residue from occurring.

Hereinafter, an embodiment of the present invention will be described.
The workpiece processing sheet according to the present embodiment includes a substrate and a pressure-sensitive adhesive layer laminated on one side of the substrate. The substrate includes a resin layer formed from a resin composition containing a vinyl chloride resin and a stabilizer.

Here, the substrate in this embodiment may be composed of a single layer of the resin layer, or may be composed of multiple layers, at least one of which is the resin layer.

In the workpiece processing sheet according to this embodiment, the stabilizer includes at least one of a saturated fatty acid metal salt having a carbon number of 12 or more and less than 18 and an unsaturated fatty acid metal salt having a carbon number of 12 or more and less than 20. In the workpiece processing sheet according to this embodiment, by using these saturated fatty acid metal salts and unsaturated fatty acid metal salts as stabilizers, the occurrence of glue residue during pick-up can be effectively suppressed.

The reasons why the occurrence of adhesive residue can be suppressed in this way are thought to be, but are not limited to, the following. In a substrate made mainly of vinyl chloride resin, the heat treatment required for film formation can cause chlorine to be liberated from the vinyl chloride resin. Stabilizers are generally used to capture this free chlorine and suppress deterioration of the substrate. However, the inventors have discovered that conventional stabilizers tend to migrate (bleed out) from the inside of the substrate to the surface, and this bled-out stabilizer reduces the adhesion between the substrate and the adhesive layer, causing adhesive residue. On the other hand, the above-mentioned saturated fatty acid metal salt and unsaturated fatty acid metal salt in this embodiment are difficult to bleed out, and therefore, while fully exerting their function as stabilizers, they do not reduce the adhesion between the substrate and the adhesive layer, and can effectively suppress the occurrence of adhesive residue.

1. Configuration of the Workpiece Processing Sheet (1) Substrate As described above, the substrate in this embodiment includes a resin layer formed from a resin composition containing a vinyl chloride resin and a stabilizer.

As described above, the substrate in this embodiment may be a single layer of the resin layer, or may be a multi-layer substrate having at least one of the resin layers. A substrate made of a single resin layer is preferable in terms of reducing manufacturing costs. On the other hand, a substrate made of multiple layers is preferable in terms of achieving both the adhesive transfer suppression effect mainly due to the resin layer and the desired effect due to layers other than the resin layer.

When the substrate has a layer other than the resin layer, the material of the layer is not particularly limited as long as it allows the formation of the layer and the substrate.

(1-1) Vinyl chloride resin In the present embodiment, the vinyl chloride resin means all polymers having a repeating unit represented by -CH ₂ -CHCl-, and includes homopolymers of vinyl chloride, copolymers of vinyl chloride and polymerizable monomers such as ethylene-vinyl chloride copolymers, modified homopolymers or copolymers such as chlorinated vinyl chloride copolymers, and chlorinated polyolefins structurally similar to vinyl chloride resins such as chlorinated polyethylene. The vinyl chloride resin contained in the resin composition for forming the resin layer in the present embodiment is not particularly limited, and any of the above-mentioned resins may be used. The above-mentioned vinyl chloride resins may be used alone or in combination of two or more.

The vinyl chloride resin preferably has a lower limit of an average degree of polymerization of 300 or more, more preferably 800 or more. The vinyl chloride resin preferably has an upper limit of an average degree of polymerization of 2500 or less, more preferably 2000 or less. When the average degree of polymerization is within the above range, the resin has excellent moldability and processability, and can be easily processed into a uniform thin film. Here, the average degree of polymerization of the vinyl chloride resin is a value measured in accordance with JIS K6720-2:1999.

(1-2) Stabilizer As described above, the stabilizer in this embodiment includes at least one of a saturated fatty acid metal salt having 12 or more and less than 18 carbon atoms and an unsaturated fatty acid metal salt having 12 or more and less than 20 carbon atoms.

Examples of saturated fatty acids that make up saturated fatty acid metal salts with 12 or more and less than 18 carbon atoms include lauric acid (12 carbon atoms), myristic acid (14 carbon atoms), palmitic acid (16 carbon atoms), etc.

Examples of unsaturated fatty acids that make up unsaturated fatty acid metal salts having 12 or more and less than 20 carbon atoms include myristoleic acid (14 carbon atoms), palmitoleic acid (16 carbon atoms), oleic acid (18 carbon atoms), and elaidic acid (18 carbon atoms).

Examples of metals constituting the above-mentioned saturated fatty acid metal salts and the above-mentioned unsaturated fatty acid metal salts include zinc, barium, sodium, potassium, magnesium, calcium, aluminum, lead, chromium, molybdenum, tungsten, manganese, iron, cobalt, etc.

In particular, preferred examples of the saturated fatty acid metal salt in this embodiment include zinc laurate and zinc palmitate. In addition, preferred examples of the unsaturated fatty acid metal salt in this embodiment include zinc oleate.

In this embodiment, the saturated fatty acid metal salt and the unsaturated fatty acid metal salt may be used alone or in combination of two or more.

In addition, in this embodiment, other stabilizers may be used in addition to the saturated fatty acid metal salt and the unsaturated fatty acid metal salt.

The content of the stabilizer in the resin composition for forming the resin layer is preferably 0.01 parts by mass or more, and more preferably 0.5 parts by mass or more, per 100 parts by mass of the vinyl chloride resin. The content of the stabilizer in the resin composition is preferably 8 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the vinyl chloride resin. By keeping the content of the stabilizer within the above range, it is possible to effectively suppress the occurrence of adhesive residue while sufficiently suppressing deterioration of the substrate.

Whether or not the base material constituting a certain work processing sheet contains the above-mentioned saturated fatty acid metal salt or unsaturated fatty acid metal salt can be confirmed from the mass spectrum obtained by analyzing the base material using time-of-flight secondary ion mass spectrometry (TOF-SIMS) as described in the test example below. In particular, this analysis makes it possible to clearly determine whether the number of carbon atoms is 16 or 18, and whether the fatty acid is saturated or unsaturated.

(1-3) Other Components The resin composition for forming the resin layer may contain other components in addition to the vinyl chloride resin and stabilizer described above. In particular, the resin composition may contain components used in the base material of general workpiece processing sheets.

Examples of such components include various additives such as plasticizers, auxiliaries, pigments, antistatic agents, flame retardants, lubricants, antioxidants, infrared absorbers, and ultraviolet absorbers. The content of these additives is not particularly limited, but is preferably within a range in which the substrate exhibits the desired function.

In particular, the resin composition for forming the resin layer preferably contains a plasticizer. By containing a plasticizer, the substrate is more likely to have good flexibility. Examples of plasticizers include phthalic acid, adipic acid, polyester, etc.

When the resin composition for forming the resin layer contains a plasticizer, the content of the plasticizer in the resin composition is preferably 18 parts by mass or more, and more preferably 25 parts by mass or more, per 100 parts by mass of the vinyl chloride resin. The content of the plasticizer in the resin composition is preferably 60 parts by mass or less, and more preferably 55 parts by mass or less, per 100 parts by mass of the vinyl chloride resin. By having the plasticizer content in the above range, the substrate tends to have good flexibility.

(1-4) Surface Treatment of Substrate The surface of the substrate on which the pressure-sensitive adhesive layer is laminated may be subjected to a surface treatment such as a primer treatment, a corona treatment, a plasma treatment, a roughening treatment (matt processing), etc., in order to enhance adhesion to the pressure-sensitive adhesive layer. Examples of the roughening treatment include an embossing method and a sandblasting method. Among these, embossing is preferred.

(1-5) Method for Producing Substrate The method for producing the substrate in this embodiment is not particularly limited as long as the above-mentioned resin composition is used, and for example, melt extrusion methods such as the T-die method and the round die method, calendar method, solution method such as the dry method and the wet method, etc. can be used. Among these, from the viewpoint of efficiently producing the substrate, it is preferable to adopt the melt extrusion method, and it is particularly preferable to adopt the T-die method.

When a substrate consisting of only a single resin layer is manufactured by melt extrusion, the resin composition is kneaded, and the resulting kneaded product is either directly produced or pelletized and then formed into a film using a known extruder. In this case, it is preferable to immediately cool the film to room temperature using a cooling roll or the like immediately after extrusion using the extruder, from the viewpoint of making it easier to achieve the above-mentioned degree of crystallinity.

When a multi-layer substrate is manufactured by melt extrusion, the components constituting each layer are mixed and then the resulting mixture is extruded directly or after pellets are first produced, using a known extruder to simultaneously extrude the layers to form a film. In this case, too, it is preferable to immediately cool the extrusion to room temperature from the viewpoint of making it easier to achieve the above-mentioned degree of crystallinity.

(1-6) Thickness of the substrate In this embodiment, the thickness of the substrate is preferably 25 μm or more, particularly preferably 50 μm or more. The thickness of the substrate is preferably 200 μm or less, particularly preferably 150 μm or less. By making the thickness of the substrate 25 μm or more, the workpiece processing sheet is likely to have a moderate strength, and the workpiece fixed on the workpiece processing sheet is likely to be well supported. In addition, by making the thickness of the substrate 11 200 μm or less, the thickness of the workpiece processing sheet is likely to have good flexibility, and for example, it is likely to be easily expanded.

(2) Adhesive Layer The adhesive constituting the adhesive layer in this embodiment is not particularly limited as long as it can exert sufficient adhesive strength to the adherend (particularly, sufficient adhesive strength to the workpiece for processing the workpiece). Examples of adhesives constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, etc. Among these, it is preferable to use acrylic adhesives from the viewpoint of easily exerting the desired adhesive strength.

The adhesive constituting the adhesive layer in this embodiment may be an adhesive that does not have active energy ray curing properties, but is preferably an adhesive that has active energy ray curing properties (hereinafter, may be referred to as an "active energy ray curable adhesive"). Since the adhesive layer is composed of an active energy ray curable adhesive, the adhesive layer can be cured by irradiation with active energy rays, and the adhesive strength of the workpiece processing sheet to the adherend can be easily reduced. In particular, irradiation with active energy rays makes it possible to easily separate the processed workpiece from the workpiece processing sheet.

The active energy ray curable adhesive constituting the adhesive layer may be one whose main component is a polymer having active energy ray curability, or may be one whose main component is a mixture of a non-active energy ray curable polymer (a polymer not having active energy ray curability) and a monomer and/or oligomer having at least one active energy ray curable group. The active energy ray curable adhesive may also be a mixture of a polymer having active energy ray curability and a monomer and/or oligomer having at least one active energy ray curable group.

The active energy ray curable polymer is preferably a (meth)acrylic acid ester polymer (hereinafter sometimes referred to as an "active energy ray curable polymer") having a functional group (active energy ray curable group) having active energy ray curability introduced into the side chain. This active energy ray curable polymer is preferably obtained by reacting an acrylic polymer having a functional group-containing monomer unit with an unsaturated group-containing compound having a functional group bonded to the functional group. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the concept of "copolymer" is also included in "polymer".

The acrylic polymer having the functional group-containing monomer unit described above may be obtained by polymerizing other monomers together with the functional group-containing monomer. As such functional group-containing monomers and other monomers, as well as the unsaturated group-containing compounds described above, known compounds can be used, and for example, those disclosed in WO 2018/084021 can be used.

The weight average molecular weight of the active energy radiation curable polymer is preferably 10,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more. The weight average molecular weight is preferably 1,500,000 or less, and even more preferably 1,000,000 or less. In this specification, the weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

As the above-mentioned active energy ray non-curable polymer component, for example, the above-mentioned acrylic polymer before reacting with the unsaturated group-containing compound can be used.

The weight average molecular weight of the acrylic polymer as the non-curable polymer component is preferably 10,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more. The weight average molecular weight is preferably 1,500,000 or less, and even more preferably 1,000,000 or less.

As the monomer and/or oligomer having at least one active energy ray-curable group, for example, an ester of a polyhydric alcohol and (meth)acrylic acid can be used.

When ultraviolet light is used as the active energy ray for curing the active energy ray-curable adhesive, it is preferable to add a photopolymerization initiator to the adhesive. In addition, the adhesive may be added with an active energy ray non-curable polymer component or oligomer component, a crosslinking agent, etc.

In this embodiment, the thickness of the adhesive layer is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. In addition, the thickness of the adhesive layer is preferably 70 μm or less, more preferably 30 μm or less, and even more preferably 10 μm or less. By having the thickness of the adhesive layer within the above-mentioned range, the work processing sheet according to this embodiment is more likely to exhibit the desired adhesiveness.

(3) Release sheet In the workpiece processing sheet according to this embodiment, a release sheet may be laminated to the side of the adhesive layer opposite the substrate (hereinafter sometimes referred to as the "adhesive side") in order to protect said side until it is attached to the workpiece.

The release sheet may have any configuration, and may be, for example, a plastic film that has been subjected to a release treatment using a release agent or the like. Specific examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. The release agent may be silicone-based, fluorine-based, or long-chain alkyl-based, and among these, silicone-based agents are preferred because they are inexpensive and provide stable performance.

There are no particular limitations on the thickness of the release sheet, and it may be, for example, 20 μm or more and 250 μm or less.

(4) Others In the workpiece processing sheet according to this embodiment, an adhesive layer may be laminated on the surface of the adhesive layer opposite to the substrate. In this case, the workpiece processing sheet according to this embodiment can be used as a dicing/die bonding sheet. In this sheet, a workpiece is attached to the surface of the adhesive layer opposite to the adhesive layer, and the adhesive layer is diced together with the workpiece to obtain a chip on which the individualized adhesive layer is laminated. The individualized adhesive layer makes it possible for the chip to be easily fixed to the object on which the chip is mounted. As the material constituting the above-mentioned adhesive layer, it is preferable to use one containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, one containing a B-stage (semi-cured) thermosetting adhesive component, or the like.

In addition, in the workpiece processing sheet according to this embodiment, a protective film forming layer may be laminated on the adhesive surface of the adhesive layer. In this case, the workpiece processing sheet according to this embodiment can be used as a sheet for forming a protective film and dicing. In such a sheet, a workpiece is attached to the surface of the protective film forming layer opposite to the adhesive layer, and the protective film forming layer is diced together with the workpiece to obtain a chip on which an individualized protective film forming layer is laminated. As the workpiece, it is preferable to use one having a circuit formed on one side, and in this case, the protective film forming layer is usually laminated on the surface opposite to the surface on which the circuit is formed. The individualized protective film forming layer can be cured at a predetermined timing to form a protective film having sufficient durability on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

2. Manufacturing method of the workpiece processing sheet The manufacturing method of the workpiece processing sheet according to the present embodiment is not particularly limited. For example, it is preferable to obtain the workpiece processing sheet by forming an adhesive layer on a release sheet, and then laminating one side of a substrate on the side of the adhesive layer opposite to the release sheet.

The above-mentioned adhesive layer can be formed by a known method. For example, a coating liquid containing an adhesive composition for forming the adhesive layer and, if desired, a solvent or dispersion medium is prepared. Then, the coating liquid is applied to the releasable surface of the release sheet (hereinafter, sometimes referred to as the "release surface"). The resulting coating film is then dried to form the adhesive layer.

The coating of the coating liquid described above can be carried out by a known method, such as bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, etc. The properties of the coating liquid are not particularly limited as long as it can be applied, and the liquid may contain the components for forming the adhesive layer as a solute or as a dispersoid. The release sheet may be peeled off as a processing material, or may protect the adhesive layer until it is applied to the adherend.

When the adhesive composition for forming the adhesive layer contains the above-mentioned crosslinking agent, it is preferable to advance the crosslinking reaction between the polymer component in the coating film and the crosslinking agent by changing the above-mentioned drying conditions (temperature, time, etc.) or by separately providing a heat treatment, and form a crosslinked structure with the desired density in the adhesive layer. Furthermore, in order to advance the above-mentioned crosslinking reaction sufficiently, after laminating the adhesive layer and the substrate, curing may be performed, for example by leaving the adhesive layer to stand for several days in an environment of 23°C and a relative humidity of 50%.

3. Method of using the workpiece processing sheet The workpiece processing sheet according to this embodiment can be used for processing a workpiece such as a semiconductor wafer. That is, after the adhesive surface of the workpiece processing sheet according to this embodiment is attached to the workpiece, the workpiece can be processed on the workpiece processing sheet. Depending on the processing, the workpiece processing sheet according to this embodiment can be used as a back grinding sheet, a dicing sheet, an expanding sheet, a pick-up sheet, or the like. Here, examples of the workpiece include semiconductor members such as semiconductor wafers and semiconductor packages, and glass members such as glass plates.

As described above, the workpiece processing sheet according to this embodiment can effectively prevent glue residue from occurring when picking up workpieces (chips, etc.) that have been diced into individual pieces. Therefore, the workpiece processing sheet according to this embodiment is particularly suitable for use as a dicing sheet, expand sheet, and pick-up sheet among the above-mentioned workpiece processing sheets.

When the workpiece processing sheet according to this embodiment has the adhesive layer described above, the workpiece processing sheet can be used as a dicing/die bonding sheet. Furthermore, when the workpiece processing sheet according to this embodiment has the protective film forming layer described above, the workpiece processing sheet can be used as a protective film forming/dicing sheet.

In addition, when the adhesive layer in the workpiece processing sheet according to this embodiment is composed of the above-mentioned active energy ray curable adhesive, it is also preferable to irradiate the adhesive layer with active energy rays during use as follows. That is, when the processing of the workpiece is completed on the workpiece processing sheet and the processed workpiece is to be separated from the workpiece processing sheet, it is preferable to irradiate the adhesive layer with active energy rays before the separation. This hardens the adhesive layer, effectively reducing the adhesive force of the adhesive sheet to the processed workpiece, making it easier to separate the processed workpiece.

The above-described embodiments are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

For example, another layer may be laminated between the substrate and the adhesive layer in the workpiece processing sheet according to this embodiment, or on the surface of the substrate opposite the adhesive layer.

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

Example 1
(1) Preparation of substrate 100 parts by mass (solid content equivalent, hereinafter the same) of vinyl chloride resin (manufactured by Taiyo Vinyl, product name "TH-1000", average polymerization degree: 1000), 30 parts by mass of di(2-ethylhexyl) terephthalate (terephthalic acid ester plasticizer, manufactured by ADEKA, product name "Adeka Cizer D-810", molecular weight: 391) as a plasticizer, 2.5 parts by mass of zinc laurate (saturated fatty acid metal salt having 12 carbon atoms, manufactured by Nitto Kasei Kogyo, product name "zinc laurate") as a stabilizer, and 0.3 parts by mass of barium stabilizer as other stabilizers were kneaded using a Banbury mixer at 180 ° C. The obtained kneaded product was rolled with a calendar roll to obtain a sheet-like substrate having a thickness of 80 μm.

(2) Preparation of adhesive composition 19 parts by mass of 2-ethylhexyl acrylate, 75 parts by mass of vinyl acetate, 1 part by mass of acrylic acid, 5 parts by mass of methyl methacrylate, and 19 parts by mass of 2-hydroxyethyl acrylate were polymerized by solution polymerization to obtain a (meth)acrylic acid ester polymer (a polymer not curable with active energy rays). The weight average molecular weight (Mw) of this (meth)acrylic acid ester polymer was measured by the method described below and was found to be 170,000.

100 parts by mass of the above (meth)acrylic acid ester polymer, 3 parts by mass of a composition containing trimethylolpropane-modified tolylene diisocyanate (TDI-TMP) as a crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L"), 5.1 parts by mass of 2,2-dimethoxy-1,2-diphenylethan-1-one (manufactured by BASF, product name "Omnirad 651") as a photopolymerization initiator, and 63.4 parts by mass of a mixture (mixed mass ratio 1:1) of a bifunctional urethane acrylate (weight average molecular weight: 11,000) and a hexafunctional urethane acrylate (weight average molecular weight: 1,500) as monomers having active energy ray-curable groups were mixed in toluene as a solvent to obtain a coating solution of an adhesive composition (solid concentration: 37% by mass).

(3) Formation of Adhesive Layer The coating solution of the adhesive composition obtained in the above step (2) was applied to the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031") consisting of a 38 μm-thick polyethylene terephthalate film having a silicone-based release agent layer formed on one side thereof, and the resulting mixture was dried by heating to obtain a laminate consisting of a 10 μm-thick adhesive layer formed on the release sheet.

(4) Preparation of workpiece processing sheet One side of the substrate obtained in the above step (1) was subjected to corona treatment. Then, the corona-treated side of the substrate and the side of the adhesive layer of the laminate obtained in the above step (3) were bonded together to obtain a workpiece processing sheet.

(5) Calculation method for measuring weight average molecular weight The weight average molecular weight (Mw) described above is a weight average molecular weight calculated in terms of standard polystyrene, measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).
<Measurement conditions>
Measuring device: Tosoh Corporation, HLC-8320
GPC columns (passed in the following order): TSK gel super H-H manufactured by Tosoh Corporation
TSK gel superHM-H
TSK gel superH2000
Measurement solvent: tetrahydrofuran Measurement temperature: 40°C

[Examples 2 to 3, Comparative Examples 1 to 3]
A workpiece processing sheet was obtained in the same manner as in Example 1, except that the types and contents of the plasticizer and stabilizer used in preparing the substrate were changed as shown in Table 1.

[Test Example 1] (TOF-SIMS evaluation of substrate)
For the substrates produced in the examples and comparative examples, mass spectra were obtained by time-of-flight secondary ion mass spectrometry (TOF-SIMS) to confirm the types of fatty acid metal salts contained therein.

Specifically, the analysis was performed using a measuring device manufactured by ION-TOF, product name "TOF.SIMS5", using _Bi3 ⁺⁺ as the primary ion, a primary ion acceleration voltage of 30 kV, a raster size of 300 μm, and positive and negative secondary ion polarities. It was confirmed whether any peaks of a saturated fatty acid metal salt with 16 carbon atoms, a saturated fatty acid metal salt with 18 carbon atoms, an unsaturated fatty acid metal salt with 16 carbon atoms, or an unsaturated fatty acid metal salt with 18 carbon atoms were detected from the obtained mass spectrum. The results are shown in Table 2.

[Test Example 2] (Evaluation of Cutting Chip Suppression)
After peeling off the release sheet from the workpiece processing sheet produced in the examples and comparative examples, the exposed surface of the exposed adhesive layer was attached to one side of an 8-inch silicon wafer using a tape mounter (manufactured by Lintec Corporation, product name "RAD2500m/12"). Next, a dicing ring frame was attached to the periphery of the exposed surface of the workpiece processing sheet (at a position that does not overlap with the silicon wafer). Furthermore, the workpiece processing sheet was cut to fit the outer diameter of the ring frame.

Thereafter, the silicon wafer was diced into individual chips having a size of 1.0 mm×1.0 mm by dicing under the following dicing conditions using a dicing device (manufactured by Disco Corporation, product name “DFD6362”).
Dicing conditions Wafer thickness: 350 μm
Dicing device: Disco Corporation, product name "DFD-6362"
Blade: Disco, product name "ZH05-SD2000-N1-90CC"
Blade rotation speed: 30,000 rpm
Cutting speed: 100mm/sec
Blade height: 0.060 mm
Cutting water amount: 1.0L/min
Cutting water temperature: 20℃

After dicing, the substrate side surface of the workpiece processing sheet was irradiated with ultraviolet light (UV) (illuminance: 230 mW/cm ² , light quantity: 190 mJ/cm ² ) using an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2000m12") to harden the adhesive layer.

Next, using a pickup device, the workpiece processing sheet was expanded at room temperature with an expansion amount of 3 mm, while the chip was pushed up using a needle at a push-up height of 300 μm and a push-up speed of 20 mm/sec. Then, simultaneously with the push-up, the chip was separated from the workpiece processing sheet with a collet of 10 mm x 10 mm in size. These operations were repeated 10 times, and the presence or absence of adhesive adhesion was visually confirmed for the surfaces of the separated 10 chips to which the workpiece processing sheet was attached, and the adhesive residue was evaluated according to the following criteria. The results are shown in Table 2.
A: No adhesive was attached to any of the 10 chips.
x: Adhesive was found to be attached to at least one chip.

The details of the compounds shown in Table 1 are as follows.
[Plasticizer]
Di(2-ethylhexyl) terephthalate: manufactured by ADEKA Corporation, product name "ADEKA Cizer D-810", molecular weight: 391
Adipic acid polyester: manufactured by ADEKA Corporation, product name "ADEKA Cizer PN-7160", average molecular weight: 800, plasticization efficiency value: 1.00
Isononyl adipate: manufactured by Shin-Nippon Rika Co., Ltd., product name "Sanso Cizer DINA", molecular weight: 398
[Stabilizer]
Zinc laurate: Metal salt of saturated fatty acid with 12 carbon atoms, manufactured by Nitto Kasei Kogyo Co., Ltd., product name "Zinc laurate"
Zinc oleate: Metal salt of unsaturated fatty acid with 18 carbon atoms, manufactured by Mitsuwa Chemical Co., Ltd., product name "Zinc oleate"
Zinc palmitate: Metal salt of saturated fatty acid with 16 carbon atoms, manufactured by Mitsuwa Chemical Co., Ltd., product name "Zinc palmitate"
Zinc stearate: Saturated fatty acid metal salt with 18 carbon atoms, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "Zinc stearate"
Zinc behenate: Metal salt of saturated fatty acid with 22 carbon atoms, manufactured by Nitto Kasei Kogyo Co., Ltd., product name "Zinc behenate"

As is clear from Table 2, the workpiece processing sheet produced in the embodiment was able to effectively suppress the occurrence of glue residue.

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

Claims (6)

A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate,
The pressure-sensitive adhesive layer is made of an active energy ray-curable pressure-sensitive adhesive, and the adhesive strength of the pressure-sensitive adhesive sheet to the workpiece is reduced by irradiation with active energy rays,
the substrate is provided with a resin layer formed from a resin composition containing a vinyl chloride resin and a stabilizer,
A workpiece processing sheet, characterized in that the stabilizer contains at least one of a saturated fatty acid metal salt having 12 or more and less than 18 carbon atoms and an unsaturated fatty acid metal salt having 12 or more and less than 20 carbon atoms. The workpiece processing sheet according to claim 1, characterized in that the content of the stabilizer in the resin composition is 0.01 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the vinyl chloride resin. The workpiece processing sheet according to claim 1 or 2, characterized in that the resin composition contains a plasticizer. The workpiece processing sheet according to any one of claims 1 to 3, characterized in that the base material is made of a single layer of the resin layer. The workpiece processing sheet according to any one of claims 1 to 3, characterized in that the base material is made up of multiple layers, at least one of which is the resin layer. The workpiece processing sheet according to any one of claims 1 to 5 , characterized in that it is a dicing sheet.