TW202303742A - Protective sheet for semiconductor processing and method for producing semiconductor device - Google Patents

Abstract

To provide a protective sheet for semiconductor processing, the protective sheet being suppressed in the occurrence of a crack in a chip when the protective sheet is removed from the chip even in cases where a wafer is processed thin by DBG or the like, while being sufficiently suppressed in the occurrence of electrification during the processing of the wafer. A protective sheet for semiconductor processing, the protective sheet comprising a base material, an antistatic layer, an energy ray-curable adhesive layer and a buffering layer, wherein the peel strength at the time when the adhesive layer after energy ray curing is peeled off from a silicon wafer at a peeling rate of 600 mm/minute in such a manner that the angle between the adhesive layer and the silicon wafer is 90 DEG is not less than 0.035 N/25 mm but less than 0.15 N/25 mm.

Description

Protective sheet for semiconductor processing and method for manufacturing semiconductor device

The present invention relates to a protective sheet for semiconductor processing and a method for manufacturing a semiconductor device. In particular, it relates to a semiconductor processing protection sheet suitable for use in a method of performing back grinding of a wafer and singulating a wafer by the stress thereof, and a method of manufacturing a semiconductor device using the semiconductor processing protection sheet.

Along with progress in miniaturization and multifunctionalization of various electronic devices, semiconductor chips mounted on these are also being pursued for miniaturization and thinning. In order to reduce the thickness of the wafer, the thickness adjustment is generally performed by grinding the back surface of the semiconductor wafer. In addition, in order to obtain a thinned wafer, a method called DBG (DBG: Dicing Before Grinding) can be used. After forming a groove with a predetermined depth from the surface side of the wafer by a dicing knife, the wafer is cut from the back side of the wafer. Grinding is performed, and the polished surface reaches the groove or the vicinity of the land groove, and the wafer is singulated to obtain a wafer. In DBG, since wafer back grinding and wafer singulation can be performed simultaneously, thin wafers can be manufactured efficiently.

In the past, in the back grinding of semiconductor wafers, when wafers were manufactured by DBG, in order to protect the circuits on the wafer surface, or to maintain the semiconductor wafer and the semiconductor wafer, generally affixed on the wafer surface is called back grinding sheet (back grinding). sheet) of adhesive tape.

As an example of a back grinding sheet, Patent Document 1 and Patent Document 2 disclose a substrate having a high Young's modulus, a buffer layer provided on one surface of the substrate, and an adhesive layer provided on the other surface. Adhesive tape.

In recent years, as a modified example of DBG, a method has been proposed in which a modified region is provided inside the wafer by laser, and the method of singulating the wafer is carried out by utilizing the stress during wafer back grinding, etc. Hereinafter, this method may be described as LDBG (Laser Dicing Before Grinding). In LDBG, since the wafer is cut along the crystallographic direction starting from the modified region, the occurrence of chipping can be reduced more than in DBG using a dicing blade. As a result, further thinning of the wafer can be achieved. In addition, compared to DBG in which a groove of a predetermined depth is formed on the wafer surface by a dicing blade, since there is no region of the wafer cut by the dicing blade, that is, since the width of the kerf is extremely small, the yield of the wafer is excellent. . [Prior Art Literature] [Patent Document]

Patent Document 1: International Publication No. 2015/156389. Patent Document 2: Japanese Patent Laid-Open No. 2015-183008.

[Problem to be solved by the invention]

During the back grinding of the wafer, the back grinding tape strongly adheres to the surface of the wafer and sufficiently protects the circuit, etc., and when the back grinding tape is peeled off from the wafer after back grinding, it needs to be easily peeled off from the wafer. Therefore, the adhesive layer of the back grinding tape attached to the wafer is generally composed of an energy ray curable adhesive. When peeling, the adhesive layer is irradiated with energy rays to harden it, and by reducing the adhesive force, both adhesiveness during back grinding and peelability after back grinding are achieved.

However, if the adhesive is not sufficiently cured by energy ray irradiation, the adhesive remains on the wafer during peeling, or chipping or breakage of the wafer occurs due to poor peeling and contact between the singulated wafers ( Hereinafter, it may also be referred to as a wafer crack). In particular, in LDBG, since the kerf width of the wafer is small, cracking of the wafer may occur even with a slight peeling failure.

In addition, it is known that static electricity is generated during wafer processing (for example, during dicing, during back grinding, during cleaning, and when peeling back grinding tape). When static electricity is generated, cut dust generated during grinding and minute foreign matter in the environment tend to adhere to the wafer or singulated wafers.

For example, if cutting dust and foreign matter adhere to the wafer during backgrinding, the pressure during backgrinding will concentrate on the attached foreign matter, and the wafer may be damaged starting from the foreign matter. In particular, in the case of performing DBG for wafer thinning and grinding, the wafer is likely to be damaged due to slight pressure concentration. Therefore, it is necessary to suppress the static electricity generated during wafer processing.

In DBG, especially LDBG, when the back grinding tapes described in Patent Document 1 and Patent Document 2 are used, cracking of the wafer when the back grinding tape is peeled off and static electricity during wafer processing cannot be sufficiently suppressed.

In view of such actual situation, the present invention aims to provide a protective sheet for semiconductor processing and a method for manufacturing a semiconductor device using the protective sheet for semiconductor processing. Even if the protective sheet for semiconductor processing is thinned by DBG or the like In the case of wafer processing, cracking of the wafer during peeling can be suppressed, and static electricity generated during wafer processing can be sufficiently suppressed. [means used to solve problems]

Aspects of the present invention are as follows. [1] A protective sheet for semiconductor processing, comprising: a base material, an antistatic layer, an energy ray-curable adhesive layer, and a buffer layer, When the adhesive layer hardened by energy rays is peeled off from the silicon wafer at a peeling speed of 600mm/min at an angle of 90ﾟ between the adhesive layer and the silicon wafer, the adhesive force is 0.035N/25mm or more, Less than 0.15N/25mm.

[2] The protective sheet for semiconductor processing as described in [1], wherein the adhesive layer cured by energy rays is peeled from the silicon wafer at an angle formed by the adhesive layer and the silicon wafer at a peeling speed of 600 mm/min. The adhesive force when peeling off in the form of 90ﾟ is relative to the adhesive layer before the energy ray is hardened, at a peeling speed of 600mm/min, from the silicon wafer at an angle of 90ﾟ to the adhesive layer and the silicon wafer The ratio of the adhesive force at the time of mode peeling is 4% or less.

[3] The protective sheet for semiconductor processing according to [1] or [2], wherein the surface resistivity of the adhesive layer after energy ray curing is 5.1×10 ¹² Ω/cm ² or more, 1.0×10 ¹⁵ Ω/cm 2 ^cm2 or less.

[4] The protective sheet for semiconductor processing according to any one of [1] to [3], wherein the Young's modulus of the substrate is 1000 MPa or more.

[5] The protective sheet for semiconductor processing according to any one of [1] to [4], wherein the protective sheet for semiconductor processing has the following configuration: an adhesive layer is provided on one main surface of the substrate, An antistatic layer is provided between the substrate and the adhesive layer, and a buffer layer is provided on the other main surface of the substrate; or, an adhesive layer is provided on one main surface of the substrate, and an adhesive layer is provided between the substrate and the adhesive. An antistatic layer and a buffer layer are arranged between the layers.

[6] The protective sheet for semiconductor processing according to any one of [1] to [5], wherein by grinding the backside of a wafer having a groove formed on the surface or a modified region formed inside, In the step of singulating the wafer into wafers, it is used by being attached to the surface of the wafer.

[7] A method of manufacturing a semiconductor device, comprising the steps of: Attaching the protective sheet for semiconductor processing as described in any one of [1] to [6] on the surface of the wafer; A step of forming a groove from the surface side of the wafer, or forming a modified region inside the wafer from the surface or back of the wafer; Attach a protective sheet for semiconductor processing to the surface, and grind the wafer with the groove or modified region formed on it from the back side, and singulate it into multiple wafers starting from the groove or modified region; From the singulated wafer, the protective sheet for semiconductor processing is peeled off. [Efficacy of the invention]

According to the present invention, it is possible to provide a protective sheet for semiconductor processing and a method of manufacturing a semiconductor device using the protective sheet for semiconductor processing, wherein the protective sheet for semiconductor processing can be used to process wafers even when the wafer is thinned by DBG or the like. The occurrence of cracks in the wafer during peeling is suppressed, and static electricity generated during wafer processing can be sufficiently suppressed.

[Mode for Carrying Out the Invention]

Hereinafter, the present invention will be described in detail based on specific embodiments using the drawings. First, main terms used in this specification will be described.

Wafer singulation refers to dividing the wafer into units of circuits to obtain wafers.

The "surface" of the wafer refers to the surface on which circuits, electrodes, etc. are formed, and the "back surface" of the wafer refers to the surface on which no circuits, etc. are formed.

DBG (Dicing Before Grinding) refers to a method in which a groove of a predetermined depth is formed on the front side of the wafer, and then ground from the back side of the wafer, and the wafer is singulated by grinding. The grooves formed on the surface side of the wafer can be formed by methods such as blade dicing, laser dicing, and plasma dicing.

In addition, LDBG (Laser Dicing Before Grinding), a modification of DBG, refers to a method of singulating wafers by setting modified regions inside the wafer by laser, and by utilizing stress during wafer back grinding.

The "wafer group" means a plurality of wafers held on the protective sheet for semiconductor processing of this embodiment after the wafers are singulated. These wafers have the same shape as the wafer as a whole.

"(Meth)acrylate" is used as a term indicating both "acrylate" and "methacrylate", and other similar terms are also the same.

The "energy ray" refers to ultraviolet rays, electron rays, etc., preferably ultraviolet rays.

Unless otherwise specified, the "weight average molecular weight" is a polystyrene-equivalent value measured by a gel chromatography (gel permeation chromatography, GPC) method. For measurement by such a method, for example, the high-speed GPC apparatus "HLC-8120GPC" manufactured by Tosoh Co., Ltd. is sequentially connected with high-speed columns "TSK guard column H _XL -H", "TSK Gel GMH _XL ", "TSK Gel G2000 H _XL " (the above are all made by Tosoh Co., Ltd.), the column temperature: 40°C, the liquid delivery rate: 1.0mL/min, and the detector was used as a differential refractive index detector.

(1. Protective sheet for semiconductor processing) The protective sheet 1 for semiconductor processing of this embodiment, as shown in FIG. The buffer layer 40 is provided on the other main surface 10b of the . From the viewpoint of antistatic function, it is preferable that the antistatic layer is close to the peeling interface of the protective sheet for semiconductor processing, that is, close to the surface 30a of the adhesive layer. Therefore, as shown in FIG. 1A , the antistatic layer 20 is preferably provided on one main surface 10 a of the substrate 10 than on the other main surface 10 b of the substrate 10 . When the protective sheet 1 for semiconductor processing is used, the surface 30a of the adhesive layer 30 is once attached to the adherend, and then peeled from the adherend.

The protective sheet for semiconductor processing is not limited to the configuration described in FIG. 1A . For example, as shown in FIG. 1B , an antistatic layer 20 , an adhesive layer 30 , and a buffer layer 40 may be provided on one main surface 10 a of a substrate 10 in the protective sheet 1 for semiconductor processing. The antistatic layer 20 and the buffer layer 40 can be disposed between the substrate 10 and the adhesive layer 30 . From the viewpoint of easy manufacture of the protective sheet for semiconductor processing, it is preferable to sequentially dispose the antistatic layer 20 , buffer layer 40 and adhesive layer 30 on the substrate 10 as shown in FIG. 1B . On the other hand, as described above, from the viewpoint of the antistatic function, it is preferable to sequentially arrange the buffer layer 40 , the antistatic layer 20 , and the adhesive layer 30 on the substrate 10 .

In addition, the protective sheet for semiconductor processing may have other layers as long as the effect of the present invention can be obtained. That is, if the protective sheet for semiconductor processing has a substrate, an antistatic layer, a buffer layer, and an adhesive layer, for example, another layer may be formed between the substrate and the buffer layer, or a layer may be formed between the substrate and the antistatic layer. other layers.

Hereinafter, the case where the protective sheet for semiconductor processing has a structure as shown in FIG. 1A is demonstrated.

As shown in FIG. 2 , by the circuit surface of the wafer 100 as the adherend, that is, the surface 30a on which the adhesive layer is attached to the surface 100a of the wafer 100, when the back surface 100b of the wafer 100 is ground, this The protective sheet 1 for semiconductor processing according to the embodiment protects the surface 100a of the wafer 100 .

As described above, when the adhesive force of the adhesive layer after energy ray curing is high, when the protective sheet for semiconductor processing is peeled off from the wafer, etc., there may be occurrence of peeling failure of the adhesive layer, damage to the wafer, or cracks. etc. tendency. Therefore, in the protective sheet for semiconductor processing of the present embodiment, the peeling failure of the adhesive layer is reduced by setting the adhesive force of the adhesive layer after energy ray curing to a predetermined range.

Here, when the amount of energy ray polymerizable carbon-carbon double bonds in the adhesive layer before curing increases, the curing of the adhesive layer tends to progress, and the adhesive force of the adhesive layer after curing tends to decrease easily. Therefore, better. However, when the amount of energy-ray-polymerizable carbon-carbon double bonds in the adhesive layer before curing increases, the crosslinking points in the adhesive layer after curing increase, making it difficult for electric charges to move and static electricity to be easily charged.

In this way, when the wafer including the above-mentioned back grinding is processed, in addition to the static electricity generated by the wafer or the wafer group, there is also static electricity generated from the adhesive layer, so it becomes difficult to alleviate the static electricity. As a result, there is a risk that more foreign matter and the like adhere to the wafer or the like due to static electricity, resulting in more damage to the wafer or the like. Therefore, in this embodiment, in addition to the adhesive force of the cured adhesive layer, the protective sheet for semiconductor processing includes an antistatic layer to relieve static electricity and reduce the static voltage of the wafer or wafer group.

Hereinafter, the constituent elements of the protective sheet for semiconductor processing will be described in detail.

(2. Substrate) The base material is not limited as long as it is made of a material that can support the wafer before the back grinding of the wafer, hold the wafer after the back grinding, and the like. For example, as a base material, various resin films used as a base material of a back grinding tape can be illustrated. The base material may be composed of a single-layer film composed of a single resin film, or may be composed of a multi-layer film composed of a plurality of resin films laminated.

(2.1 Physical properties of base material) In this embodiment, the base material is preferably highly rigid. Due to the high rigidity of the substrate, vibrations during back grinding can be suppressed. As a result, the support and holding performance of wafers, etc. can be improved, and damage, cracks, etc. of wafers, etc. can be reduced. In addition, it is possible to reduce the stress when the protective sheet for semiconductor processing is detached from the wafer or the like, and to reduce damage, cracks, etc. to the wafer or the like during detachment. Furthermore, workability at the time of attaching the protective sheet for semiconductor processing to a wafer becomes favorable. Specifically, the Young's modulus of the substrate at 23° C. is preferably above 1000 MPa, more preferably above 1800 MPa. The upper limit of Young's modulus is not particularly limited, but is about 30000 MPa.

In this embodiment, the thickness of the substrate is preferably not less than 15 μm and not more than 110 μm, more preferably not less than 20 μm and not more than 105 μm.

(2.2 Material of base material) As a material of a base material, a material can be selected so that the Young's modulus of a base material may fall in the said range. In this embodiment, for example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and wholly aromatic polyesters, polyimides, Polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfide, polyether ketone, biaxially stretched polypropylene, etc. Among these, one or more selected from polyester, polyamide, polyimide, and biaxially stretched polypropylene is preferable, polyester is more preferable, and polyethylene terephthalate is still more preferable. .

In addition, the substrate may contain plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, catalysts, etc. within the range that does not impair the effects of the present invention. In addition, the substrate may be transparent or opaque, and may be colored or vapor-deposited as required.

In addition, in order to improve the adhesiveness with other layers, you may apply an adhesive treatment, such as a corona treatment, to at least one main surface of a base material. In addition, the substrate may have a primer layer on at least one of the main surfaces.

The primer layer-forming composition for forming the primer layer is not particularly limited, and examples thereof include polyester-based resins, urethane-based resins, polyester-urethane-based resins, and acrylic resins. combination. The composition for forming a primer layer may optionally contain a crosslinking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, an antirust agent, a pigment, a dye, and the like.

The thickness of the primer layer is preferably 0.01-10 μm, more preferably 0.03-5 μm. Since the material of the primer layer is soft, it has little influence on the Young's modulus. Even with the primer layer, the Young's modulus of the substrate is substantially the same as the Young's modulus of the resin film.

For example, the Young's modulus of the substrate can be controlled by the selection of resin composition, the addition of plasticizer, the stretching conditions during the production of the resin film, and the like.

(3. Adhesive layer) The adhesive layer is attached to the circuit surface of the semiconductor wafer until it is peeled off from the circuit surface to protect the circuit surface and support the semiconductor wafer. In this embodiment, the adhesive layer is energy ray curable. The adhesive layer may be composed of one layer (single layer), or may be composed of two or more layers. When the adhesive layer has plural layers, these plural layers may be the same as or different from each other, and the combination of layers constituting these plural layers is not particularly limited.

The thickness of the adhesive layer is not particularly limited, but is preferably not less than 3 μm and not more than 200 μm, more preferably not less than 5 μm and not more than 100 μm. When the thickness of the adhesive layer is within the above range, cracking of the wafer, movement of the wafer, and the like can be suppressed.

In addition, the thickness of the adhesive layer means the thickness of the entire adhesive layer. For example, the thickness of an adhesive layer composed of a plurality of layers means the total thickness of all the layers constituting the adhesive layer.

In this embodiment, the adhesive layer has the following physical properties.

(3.1 90ﾟ peel adhesion of adhesive layer after energy ray hardening) In this embodiment, the adhesive force when the adhesive layer hardened by energy rays is separated from the silicon wafer in such a manner that the angle formed between the adhesive layer and the silicon wafer is 90° (hereinafter referred to as after energy line hardening) The 90ﾟpeel adhesion of the adhesive layer) is more than 0.035N/25mm and less than 0.15N/25mm. When the 90ﾟpeel adhesive force of the adhesive layer hardened by the energy ray is within the above range, it is possible to sufficiently reduce the adhesive force while suppressing the occurrence of process errors caused by the tape being peeled off at an unexpected point before the predetermined peeling step, Therefore, it is easy to peel off the adhesive layer from the wafer group after back grinding. Therefore, it is possible to reduce paste residue on wafers and the like, cracks on wafers, and the like.

The 90ﾟ peel adhesion of the adhesive layer after energy ray hardening is preferably 0.14N/25mm or less, more preferably 0.13N/25mm or less.

In this embodiment, the 90ﾟ peeling adhesion of the adhesive layer after energy ray curing is based on JIS 0237. The adhesive layer is attached to the silicon wafer, and after the adhesive layer is cured by energy rays, the peeling speed is 600nm/ Under the condition of 10 minutes, the adhesive force when the hardened adhesive layer was peeled off from the silicon wafer at an angle of 90ﾟ was measured. The specific measurement conditions will be described in the following examples.

In addition, the peeling speed of 600 nm/min tends to be faster than the peeling speed at the time of usual adhesion measurement. This condition is assumed to be the peeling speed when the adhesive layer is peeled off from a wafer polished by DBG or LDBG, or the like. As the peeling speed increases, the general adhesive force tends to increase.

(3.2 90ﾟ peel adhesion ratio of the adhesive layer before and after energy ray hardening) In this embodiment, the ratio of the 90ﾟpeel adhesive strength of the adhesive layer before and after energy ray hardening is preferably 4% or less. In other words, the 90ﾟ peeling adhesive force of the adhesive layer after the energy ray hardening is compared to that of the adhesive layer before the energy ray hardening is peeled off from the silicon wafer at an angle of 90ﾟ between the adhesive layer and the silicon wafer. The ratio of the adhesive force (hereinafter referred to as the 90ﾟpeel adhesive force of the adhesive layer before energy ray hardening) (hereinafter referred to as the adhesive force ratio) is preferably 4% or less.

When the adhesive force ratio is within the above range, the adhesive layer can be sufficiently adsorbed on the surface of the wafer to protect the circuit during back grinding, and at the same time, the adhesive layer can be easily peeled off from the wafer after back grinding, and cracks on the wafer can be suppressed. .

The adhesion ratio is more preferably below 3%, and more preferably below 2%. On the other hand, the lower limit of the adhesive force ratio is not particularly limited, but is usually about 0.3%.

The 90ﾟ peel adhesion of the adhesive layer before energy ray hardening can be measured in the same way as the 90ﾟ peel adhesion of the adhesive layer after energy ray hardening, except for measuring the adhesion of the adhesive layer before energy ray hardening . The specific measurement conditions will be described in the following examples.

(3.3 Surface Resistivity) In this embodiment, the surface resistivity of the adhesive layer after energy ray curing is preferably not less than 5.1×10 ¹² Ω/cm ² and not more than 1.0×10 ¹⁵ Ω/cm ² . In addition, this surface resistivity is the surface resistivity of the surface attached to the adherend (in FIG. 1A, the surface 30a of the adhesive layer) among the surfaces of the adhesive layer.

The present inventors found that the amount of carbon-carbon double bonds in the adhesive layer before hardening not only affects the adhesive force of the adhesive layer after hardening, but also affects the electrostatic properties of the adhesive layer. That is, even if the protective sheet for semiconductor processing according to the present embodiment has an antistatic layer, foreign matter or the like adheres to the wafer or the like due to static electricity of the wafer or the wafer group. Therefore, in such a case, for example, by controlling the amount of energy-ray-polymerizable carbon-carbon double bonds in the adhesive layer before hardening, it is preferable to control the surface resistivity of the adhesive layer within the above-mentioned range. .

By setting the surface resistivity within the above range, static electricity can easily escape from the protective sheet for semiconductor processing, and the wafer or wafer group can be suppressed from being charged with static electricity during processing of the wafer to which the protective sheet for semiconductor processing is attached. As a result, in the step of attaching the protective sheet for semiconductor processing to the surface of the wafer, the step of grinding the back surface of the wafer, the step of peeling off the protective sheet for semiconductor processing, and the wafer or wafer group after peeling off the protective sheet for semiconductor processing In the transfer process and the like, it is possible to suppress foreign matter and the like from adhering to the wafer and the like. Therefore, it is possible to suppress breakage and cracking of the wafer or the like due to adhesion of foreign matter.

In addition, when the surface resistivity is smaller than the above-mentioned range, for example, it shows that the curing of the adhesive layer is insufficient. As a result, when the protective sheet for semiconductor processing is peeled off, it cannot be peeled off well from the wafer or the wafer, and a part of the adhesive layer remains attached to the wafer or the wafer (paste remains), causing cracks in the wafer.

The surface resistivity is more preferably not more than 9.5×10 ¹⁴ Ω/cm ² , more preferably not more than 9.0×10 ¹⁴ Ω/cm ² . On the other hand, the surface resistivity is preferably at least 5.2×10 ¹² Ω/cm ² , more preferably at least 5.5×10 ¹² Ω/cm ² .

In the present embodiment, the surface resistivity is measured in accordance with JIS K 7194. That is, it is measured in the same manner as the measurement method prescribed in JIS K 7194, but the measurement conditions may be different. The specific measurement conditions will be described in the following examples.

(3.4 Composition of Adhesive Layer) The composition of the adhesive layer is not particularly limited as long as the adhesive layer before hardening can protect the circuit surface of the wafer and the adhesive force of the adhesive layer after hardening is within the above range. In this embodiment, as the adhesive component (adhesive resin) capable of exhibiting adhesiveness, the adhesive layer is made of, for example, an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, It is preferably composed of a composition such as an adhesive (composition for an adhesive layer).

In addition, the composition for an adhesive layer contains an energy ray-curable adhesive from the viewpoint of easily achieving the above-mentioned adhesive force and adhesive force ratio after energy ray curing.

(3.5 Composition for Adhesive Layer) As mentioned above, since the adhesive layer is energy ray curable, it is formed from the composition (composition for adhesive layer) which has energy ray curability. Hereinafter, the composition for adhesive agent layers is demonstrated.

An energy ray curable composition different from the adhesive resin may be formulated to impart energy ray curability to the adhesive layer composition, but it is preferable that the above adhesive resin itself has energy ray curability. When the adhesive resin itself has energy ray curability, an energy ray polymerizable group is introduced into the adhesive resin, but it is preferable to introduce an energy ray polymerizable group into the main chain or side chain of the adhesive resin.

In addition, when compounding an energy ray-curable compound different from the adhesive resin, a monomer or oligomer having an energy ray polymerizable group is used as the energy ray-curable compound. The oligomer is an oligomer having a weight average molecular weight (Mw) of less than 10,000, and examples thereof include urethane (meth)acrylate.

In the present embodiment, from the viewpoint of controlling the amount of carbon-carbon double bonds of energy ray polymerizability, it is preferably 0.1 to 300 parts by mass, and more preferably It is 0.5-200 mass parts, More preferably, it is 1-150 mass parts.

In the following, the energy ray-curable adhesive resin contained in the composition for an adhesive layer is an energy ray-curable acrylic compound (hereinafter also referred to as "acrylic polymer (A)"). More details.

(3.5.1 Acrylic polymer (A)) The acrylic polymer (A) is an acrylic polymer having an energy ray polymerizable group introduced therein and a structural unit derived from (meth)acrylate. The energy ray polymerizable group is preferably introduced into a side chain of an acrylic polymer.

The acrylic polymer (A) is an acrylic copolymer (A0) having a constituent unit derived from an alkyl (meth)acrylate (a1) and a constituent unit derived from a functional group-containing monomer (a2), The reactant reacting with the polymerizable compound (Xa) having an energy ray polymerizable group is preferable.

As the alkyl (meth)acrylate (a1), an alkyl (meth)acrylate having 1 to 18 carbon atoms in the alkyl group is used. Specifically, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, (meth)acrylate Base) n-hexyl acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, dodecyl (meth)acrylate, ( Tridecyl methacrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, etc.

Among these, the alkyl (meth)acrylate (a1) is preferably an alkyl (meth)acrylate having 4 to 8 carbon atoms in the alkyl group. Specifically, 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate are preferable, and n-butyl (meth)acrylate is more preferable. In addition, these may be used individually by 1 type, and may use it in combination of 2 or more types.

In the acrylic copolymer (A0), from the viewpoint of enhancing the formed adhesive layer, the amount derived from the (meth)acrylic acid alkyl group is The content of the constituent units of the ester (a1) is preferably from 40 to 98% by mass, more preferably from 45 to 95% by mass, and still more preferably from 50 to 90% by mass.

For example, the alkyl (meth)acrylate (a1) may contain ethyl (meth)acrylate in addition to the above-mentioned 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate. , Methyl (meth)acrylate, etc. By containing these monomers, the adhesive performance of an adhesive layer becomes easy to adjust to a desired one.

The functional group-containing monomer (a2) is a monomer having a functional group such as a hydroxyl group, a carboxyl group, an epoxy group, an amino group, a cyano group, a nitrogen atom-containing ring group, or an alkoxysilyl group. As the functional group-containing monomer (a2), among the above, one or more selected from the group consisting of hydroxyl group-containing monomers, carboxyl group-containing monomers, and epoxy group-containing monomers is preferable.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, -Hydroxyalkyl (meth)acrylates such as hydroxybutyl, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol; and the like.

As a carboxyl group-containing monomer, (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid etc. are mentioned, for example.

Examples of the epoxy group-containing monomer include epoxy group-containing (meth)acrylate and non-acrylic epoxy group-containing monomers. Examples of epoxy group-containing (meth)acrylates include glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, (3,4-cyclo Oxycyclohexyl)methyl ester, 3-epoxycyclo-2-hydroxypropyl (meth)acrylate, etc. Moreover, as a non-acrylic-type epoxy group containing monomer, crotonic-acid glycidyl ester, an allyl glycidyl ether, etc. are mentioned, for example.

The functional group-containing monomer (a2) may be used alone or in combination of two or more.

As the functional group-containing monomer (a2), among the above, hydroxyl-containing monomers are more preferred, among which, hydroxyl (meth)acrylate is more preferred, and 2-hydroxyethyl (meth)acrylate is preferred. For better.

As (a2) component, an acrylic-type copolymer (A0) and a polymeric compound (Xa) can be made to react relatively easily by using a hydroxy (meth)acrylic acid alkyl ester.

In the acrylic copolymer (A0), the content of the structural unit derived from the functional group-containing monomer (a2) is preferably 1 to 35% by mass relative to the total structural units (100% by mass) of the acrylic copolymer (A0). %, more preferably 3 to 32% by mass, further preferably 6 to 30% by mass.

When the content is 1% by mass or more, a certain amount of functional groups serving as reaction points with the polymerizable compound (Xa) can be secured. Therefore, by properly curing the adhesive layer by irradiation of energy rays, the adhesive force after irradiation of energy rays can be reduced. In addition, when the content is 30% by mass or less, a sufficient pot life (pot life) can be ensured when the solution of the adhesive layer composition is applied to form the adhesive layer.

The acrylic copolymer (A0) may be a copolymer of an alkyl (meth)acrylate (a1) and a functional group-containing monomer (a2), or may be a component (a1), a component (a2), these (a1) and a copolymer of other monomers (a3) other than the component (a2).

Examples of other monomers (a3) include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, (meth)acrylates having a ring structure such as dicyclopentenyl (meth)acrylate and dicyclopentenyloxyethyl (meth)acrylate, vinyl acetate, styrene, and the like. Other monomers (a3) may be used alone or in combination of two or more.

In the acrylic copolymer (A0), the content of the structural units derived from other monomers (a3) is preferably 0 to 30% by mass relative to the total structural units (100% by mass) of the acrylic copolymer (A0) , more preferably 0 to 10% by mass, more preferably 0 to 5% by mass.

The polymerizable compound (Xa) is a substituent having an energy ray polymerizable group and capable of reacting with a functional group in a structural unit derived from the component (a2) of the acrylic copolymer (A0) (hereinafter also referred to simply as " reactive substituents").

The energy ray polymerizable group may be a group including an energy ray polymerizable carbon-carbon double bond. For example, (meth)acryl group, vinyl group, etc. are mentioned, and (meth)acryl group is preferable. In addition, the polymerizable compound (Xa) is preferably a compound having 1 to 5 energy ray polymerizable groups per molecule.

The reactive substituent in the polymerizable compound (Xa) can be appropriately changed according to the functional group of the functional group-containing monomer (a2), for example, isocyanate group, carboxyl group, epoxy group, etc. From the point of view, the isocyanate group is preferable. When the polymeric compound (Xa) has an isocyanate group, for example, when the functional group of a functional group containing monomer (a2) is a hydroxyl group, it can react easily with an acryl-type copolymer (A0).

Specific polymerizable compounds (Xa) include, for example, (meth)acryloxyethyl isocyanate, methyl-isopropenyl-α,α-dimethylbenzyl isocyanate, (meth)acryl Alkyl isocyanate, allyl isocyanate, glycidyl (meth)acrylate, (meth)acrylic acid, etc. These polymerizable compounds (Xa) can be used alone or in combination of two or more.

Among these, (meth)acryloxyethyl isocyanate is preferable as the above-mentioned reactive substituent from the viewpoint of a compound having a suitable isocyanate group and having an appropriate distance between the main chain and the energy ray polymerizing group. .

From the viewpoint of controlling the amount of carbon-carbon double bonds for energy ray polymerizability, among the total amount (100 equivalents) of functional groups (100 equivalents) derived from the functional group-containing monomer (a2) in the acrylic copolymer (A0), the polymerizability The compound (Xa) is preferably 50 to 98 equivalents, more preferably 55 to 93 equivalents to react with the functional group.

The weight average molecular weight (Mw) of the acrylic polymer (A) is preferably from 300,000 to 1.6 million, more preferably from 400,000 to 1.4 million. By having such Mw, suitable adhesiveness can be imparted to an adhesive layer.

Even when the adhesive resin has energy ray curability, the composition for an adhesive layer preferably contains an energy ray curable compound other than the adhesive resin. Such an energy ray curable compound is preferably a monomer or oligomer which has an unsaturated group in the molecule and is polymerizable and hardenable by energy ray irradiation.

Specifically, for example, trimethylolpropane tri(meth)acrylate, neopentylthritol (meth)acrylate, neopentylthritol tetra(meth)acrylate, dipenteoerythritol hexaacrylate, Polyvalent (meth)acrylate monomers such as (meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol (meth)acrylate, urethane Oligomers of ethyl (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, epoxy (meth)acrylate, etc.

Among these, the urethane (meth)acrylate oligomer is preferable from the viewpoint that the molecular weight is relatively high and the surface resistivity of the adhesive layer is within the above-mentioned range.

From the viewpoint of controlling the amount of carbon-carbon double bonds that can polymerize energy rays, the content of the energy ray-curable compound is preferably 0.1 to 300 parts by mass, more preferably 0.1 to 300 parts by mass, based on 100 parts by mass of the acrylic polymer (A). 0.5 to 200 parts by mass, more preferably 1 to 150 parts by mass.

(3.5.2 Cross-linking agent) The composition for an adhesive layer preferably further contains a crosslinking agent. The composition for an adhesive layer is crosslinked via a crosslinking agent, for example, by heating after coating. The adhesive layer is cross-linked by the acrylic polymer (A) through the cross-linking agent to form a coating film appropriately, and it is easy to exhibit the function as the adhesive layer.

Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, and chelate-based crosslinking agents. Among these, isocyanate-based crosslinking agents are preferred. A crosslinking agent can be used individually or in combination of 2 or more types.

A polyisocyanate compound is mentioned as an isocyanate type crosslinking agent. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; isophorone diisocyanate, hydrogenated Alicyclic polyisocyanate, such as diphenylmethane diisocyanate, etc. In addition, these biuret forms, isocyanurate forms, and low-molecular-weight active hydrogen-containing compounds further mixed with ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. Additives of reactants, etc.

Among the above, polyol (for example, trimethylolpropane, etc.) adducts of aromatic polyisocyanates such as toluene diisocyanate are preferred.

The content of the crosslinking agent is preferably from 0.01 to 10 parts by mass, more preferably from 0.03 to 7 parts by mass, relative to 100 parts by mass of the acrylic polymer (A).

(3.5.3 Photopolymerization initiator) The composition for an adhesive layer preferably further contains a photopolymerization initiator. When the composition for an adhesive layer contains a photopolymerization initiator, it becomes easy to harden the composition for an adhesive layer by energy rays, such as an ultraviolet-ray.

Examples of the polymerization initiator include acetophenone, 2,2-diethoxybenzophenone, 4-methylbenzophenone, and 2,4,6-trimethylbenzophenone. , Michler's ketone (Michler's ketone), benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, benzyl dimethyl ketal, dibenzyl, diacetyl, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-ethylanthraquinone, 2,2-dimethoxy-1,2-diphenylethane- 1-keto, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanol-1,2-benzyl-2-di Methylamino-1-(4-morpholinophenyl)-butanone-1,2-hydroxy-2-methyl-1-phenyl-propan-1-one, diethylthioxanthone, iso Low molecular weight polymerization initiators such as propylthioxanthone, 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide, oligo{2-hydroxy-2-methyl-1-[4 - oligomerized polymerization initiators such as (1-methylvinyl)phenyl]acetone} and the like.

Moreover, a photoinitiator can be used individually or in combination of 2 or more types. In addition, among the above, 2,2-dimethoxy-1,2-diphenylethan-1-one and 1-hydroxycyclohexyl phenyl ketone are preferable.

The content of the photopolymerization initiator is preferably from 0.01 to 10 parts by mass, more preferably from 0.03 to 7 parts by mass, and still more preferably from 0.05 to 5 parts by mass, based on 100 parts by mass of the acrylic polymer (A).

The composition for an adhesive layer may contain other additives in the range which does not impair the effect of this invention. Examples of other additives include thickeners, antioxidants, softeners (plasticizers), fillers, antirust agents, pigments, dyes, and the like. When these additives are contained, the content of each additive is preferably 0.01 to 6 parts by mass, more preferably 0.02 to 2 parts by mass, relative to 100 parts by mass of the acrylic polymer (A).

In addition, the adhesive force of the adhesive layer can be adjusted by, for example, the type and amount of monomers constituting the acrylic polymer (A), the amount of energy ray polymerizable groups introduced into the acrylic polymer (A), and the like. In addition, the surface resistivity of the adhesive layer can also be adjusted to some extent based on these. In the above, the preferred range of the amount of energy ray polymerizable groups introduced into the acrylic polymer (A) is described. For example, if the amount of energy ray polymerizable groups is increased, the adhesive force after curing becomes low, and the surface resistance becomes lower. tendency to increase. However, the adhesive force and surface resistivity of the adhesive layer can also be adjusted based on factors other than the above factors. For example, it can also adjust suitably according to the quantity of the crosslinking agent mix|blended in an adhesive layer, and the quantity of a photopolymerization initiator.

(4. Antistatic layer) The antistatic layer is configured between the substrate and the adhesive layer. In the antistatic layer, the antistatic component suppresses an increase in static voltage due to static electricity during processing of a wafer to which a protective sheet for semiconductor processing is attached. The composition of the antistatic layer may have antistatic properties to the extent that the peeling static voltage when the adhesive layer is peeled from the wafer or the like is equal to or less than a predetermined value. In this embodiment, the peeling electrostatic voltage is preferably set to 500V or less.

The thickness of the antistatic layer is preferably at least 10 nm, more preferably at least 15 nm, more preferably at least 20 nm, and particularly preferably at least 60 nm. In addition, the thickness is preferably not more than 300 nm, more preferably not more than 250 nm, and still more preferably not more than 200 nm.

(4.1 Composition for antistatic layer) In this embodiment, the antistatic layer is preferably composed of a composition containing a polymer compound (composition for an antistatic layer). Examples of such a composition include a composition containing a conductive polymer compound as an antistatic component, a composition containing an antistatic component and a polymer compound, and the like. The composition for the antistatic layer is preferably a composition containing a conductive polymer compound.

Examples of the conductive high molecular compound include polythiophene-based polymers, polypyrrole-based polymers, and polyaniline-based polymers. In this embodiment, polythiophene-based polymers are preferred.

Examples of polythiophene-based polymers include polythiophene, poly(3-alkylthiophene), poly(3-thiophene-β-ethanesulfonic acid), polyalkylenedioxythiophene, and polystyrenesulfonate (PSS) mixtures (including dopers), etc. Among these, a mixture of polyalkylene dioxythiophene and polystyrene sulfonate is preferred. Examples of the aforementioned polyalkylenedioxythiophene include poly(3,4-ethylenedioxythiophene) (PEDOT), polypropylenedioxythiophene, and poly(ethylene/propylene)dioxythiophene, among which poly(3, 4-ethylenedioxythiophene) is preferred. That is, among the above, a mixture of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate (PSS-doped PEDOT) is particularly preferable.

Examples of the polypyrrole-based polymer include polypyrrole, poly-3-methylpyrrole, and poly-3-octylpyrrole.

As a polyaniline polymer, polyaniline, polymethylaniline, polymethoxyaniline etc. are mentioned, for example.

Examples of the composition comprising an antistatic component and a polymer compound include a composition comprising an antistatic component and a binder resin. As the antistatic component, the aforementioned conductive polymer compound, surfactant, ionic liquid, and conductive inorganic compound can be exemplified.

The surfactant may be at least one selected from cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants. For example, a cationic surfactant containing a quaternary ammonium salt can be illustrated. Examples of the conductive inorganic compound include various metals, conductive oxides, and the like.

In addition, the binder resin is not particularly limited. For example, polyester resin, acrylic resin, polyethylene resin, polyurethane resin, melamine resin, epoxy resin, etc. are mentioned. Examples of the crosslinking agent include methylolated or hydroxyalkylated melamine-based compounds, urea-based compounds, glyoxal-based compounds, acrylamide-based compounds, epoxy-based compounds, and isocyanate-based compounds.

The content of the antistatic agent in the composition for an antistatic layer can be appropriately determined according to desired antistatic performance. Specifically, the content of the antistatic agent in the composition for an antistatic layer is preferably 0.1 to 20% by mass.

(5. Buffer layer) As shown in FIG. 1A , a buffer layer is formed on the main surface opposite to the main surface of the substrate on which the adhesive layer is formed. The buffer layer 40 is a soft layer compared with the base material, and relieves stress during back grinding of the wafer, thereby preventing cracking and chipping of the wafer. In addition, the wafer with the protective sheet for semiconductor processing attached is placed on the vacuum table through the protective sheet for semiconductor processing during back grinding, but since it has a buffer layer as a constituent layer of the protective sheet for semiconductor processing, it is easy to be properly held on the wafer. Vacuum table.

Such a buffer layer is useful when processing a wafer with DBG, especially LDBG.

The thickness of the buffer layer is preferably 5-100 μm, more preferably 1-100 μm, and still more preferably 5-80 μm. When the thickness of the buffer layer is within the above-mentioned range, the buffer layer can moderately relax stress during back grinding.

The buffer layer may be a layer formed of a buffer layer composition containing an energy ray polymerizable compound, or may be a polypropylene film, an ethylene-vinyl acetate copolymer film, an ionomer resin film, or an ethylene-(meth)acrylic acid copolymer film. film, ethylene-(meth)acrylate copolymer film, LDPE film, LLDPE film, etc.

(5.1 Composition for Buffer Layer) The composition for a buffer layer containing an energy ray polymerizable compound can be cured by irradiating energy rays.

In addition, the buffer layer composition containing an energy ray polymerizable compound, more specifically, contains urethane (meth)acrylate (b1) and an alicyclic group or hetero group having 6 to 20 ring atoms. A ring-based polymerizable compound (b2) is preferred. In addition, the buffer composition may contain a polymerizable compound (b3) having a functional group in addition to the above-mentioned components (b1) and (b2). In addition, the buffer composition may contain a photopolymerization initiator in addition to the above components. Furthermore, the composition for buffer layers may contain other additives, a resin component, etc. in the range which does not impair the effect of this invention.

Hereinafter, each component contained in the buffer layer composition containing an energy ray polymerizable compound is demonstrated in detail.

(5.1.1 Urethane (meth)acrylate (b1)) Urethane (meth)acrylate (b1) means a compound having at least a (meth)acryl group and a urethane bond, which has a property of being polymerized and cured by energy ray irradiation. Urethane (meth)acrylate (b1) is an oligomer or a polymer.

The weight average molecular weight (Mw) of the component (b1) is preferably from 1,000 to 100,000, more preferably from 2,000 to 60,000, still more preferably from 3,000 to 20,000. In addition, the number of (meth)acryl groups in component (b1) (hereinafter also referred to as "functional group") may be monofunctional, difunctional, or trifunctional or more, but monofunctional or difunctional .

The component (b1) is obtained, for example, by reacting a (meth)acrylate having a hydroxyl group with an isocyanate-terminated urethane prepolymer obtained by reacting a polyol compound and a polyvalent isocyanate compound. Moreover, component (b1) can be used individually or in combination of 2 or more types.

The polyol compound used as a raw material of the component (b1) is not particularly limited as long as it is a compound having two or more hydroxyl groups. It can be any one of 2-functional diols, 3-functional triols, and 4-functional or more polyols, but 2-functional diols are preferred, and polyester diols or polycarbonate diols are preferred. good.

Examples of polyvalent isocyanate compounds include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; isophorone diisocyanate , norbornane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, ω,ω'-diisocyanate dimethylcyclohexane, etc. Family diisocyanates; 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, naphthalene-1, Aromatic diisocyanates such as 5-diisocyanate.

Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylene diisocyanate are preferable.

Urethane (meth)acrylate can be obtained by reacting a (meth)acrylate having a hydroxyl group with an isocyanate-terminated urethane prepolymer obtained by reacting the above polyol compound and a polyvalent isocyanate compound. (b1). It will not specifically limit as a (meth)acrylate which has a hydroxyl group, if it is a compound which has a hydroxyl group and a (meth)acryl group in at least 1 molecule.

Specific (meth)acrylates having a hydroxyl group include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. , 4-Hydroxycyclohexyl (meth)acrylate, 5-Hydroxycyclohexyl (meth)acrylate, 2-Hydroxy-3-phenoxypropyl (meth)acrylate, Neopentylthritol tri(methyl) Hydroxyalkyl (meth)acrylates of acrylates, polyethylene glycol mono(meth)acrylates, polypropylene glycol mono(meth)acrylates, etc.; N-methylol(meth)acrylamide, etc. Hydroxyl-containing (meth)acrylamides; reactants obtained by reacting (meth)acrylic acid with vinyl alcohol, vinylphenol, diglycidyl ester of bisphenol A; etc.

Among these, hydroxyalkyl (meth)acrylate is preferable, and 2-hydroxyethyl (meth)acrylate is more preferable.

The content of the component (b1) in the composition for a buffer layer is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and even more preferably It is 25~55% by mass.

(5.1.2 Polymerizable compound (b2) having an alicyclic or heterocyclic group with 6 to 20 ring atoms) Component (b2) is a polymerizable compound having an alicyclic or heterocyclic group with 6 to 20 ring atoms, preferably a compound having at least one (meth)acryl group, more preferably a compound having A compound of (meth)acryloyl group. By using the component (b2), the film-forming property of the composition for buffer layers obtained can be improved.

As a specific component (b2), for example, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentanyl (meth)acrylate Alicyclic group-containing (meth)acrylates such as alkenyloxy ester, cyclohexyl (meth)acrylate, adamantyl (meth)acrylate; tetrahydrofurfuryl (meth)acrylate, morpholine ( Heterocyclic group-containing (meth)acrylates such as meth)acrylates; and the like. Moreover, component (b2) can be used individually or in combination of 2 or more types. Among the (meth)acrylates containing alicyclic groups, isocamphoryl (meth)acrylate is preferred, and among the (meth)acrylates containing heterocyclic groups, tetrahydrofurfuryl (meth)acrylates are preferred. good.

The content of the component (b2) in the composition for a buffer layer is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and even more preferably It is 25~55% by mass.

(5.1.3 Polymerizable compound (b3) having a functional group) Component (b3) is a polymerizable compound containing a functional group such as a hydroxyl group, an epoxy group, an amido group, an amino group, etc., and is further preferably a compound having at least one (meth)acryl group, more preferably A compound having one (meth)acryloyl group.

Component (b3) has good compatibility with component (b1), and it is easy to adjust the viscosity of the buffer layer composition to an appropriate range. In addition, even if the buffer layer is made relatively thin, the buffer performance is still good.

As a component (b3), a hydroxyl group containing (meth)acrylate, an epoxy group containing compound, an amide group containing compound, an amino group containing (meth)acrylate etc. are mentioned, for example. Among these, hydroxyl group-containing (meth)acrylates are preferable.

As hydroxyl-containing (meth)acrylates, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, ( 2-Hydroxybutyl methacrylate, 3-Hydroxybutyl (meth)acrylate, 4-Hydroxybutyl (meth)acrylate, phenylhydroxypropyl (meth)acrylate, 2-Hydroxy-3-acrylate Phenoxypropyl Etc. Among these, hydroxyl-containing (meth)acrylates having an aromatic ring such as phenylhydroxypropyl (meth)acrylate are more preferable.

Moreover, component (b3) can be used individually or in combination of 2 or more types. In order to improve the film-forming properties of the composition for a buffer layer, the content of the component (b3) in the composition for a buffer layer is preferably 5 to 40% by mass relative to the total amount (100% by mass) of the composition for a buffer layer , more preferably 7 to 35% by mass, more preferably 10 to 30% by mass.

(5.1.4 Polymerizable compounds (b4) other than components (b1) to (b3)) In the range which does not impair the effect of this invention, the composition for buffer layer formation may contain other polymeric compounds (b4) other than the said component (b1)-(b3).

As the component (b4), for example, alkyl (meth)acrylates having an alkyl group having 1 to 20 carbon atoms; styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N- Vinyl compounds such as vinylformamide, N-vinylpyrrolidone, N-vinylcaprolactam, etc.; etc. Moreover, component (b4) can be used individually or in combination of 2 or more types.

The content of the component (b4) in the buffer layer composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, further preferably 0 to 5% by mass, and particularly preferably 0 to 2% by mass.

(5.1.5 Photopolymerization initiator) In the composition for a buffer layer, when forming a buffer layer, it is preferable to further contain a photopolymerization initiator from the viewpoint of shortening the polymerization time by energy ray irradiation or reducing the amount of energy ray irradiation.

As photopolymerization initiators, for example, benzoin compounds, acetophenone compounds, acyl phosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, further photosensitive compounds such as amines and quinones, etc. Agents, etc., more specifically, for example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ether , benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis(2,4, 6-trimethylbenzoyl)phenylphosphine oxide, etc.

These photopolymerization initiators can be used individually or in combination of 2 or more types.

The content of the photopolymerization initiator in the composition for a buffer layer is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3~5 parts by mass.

(5.1.6 Other additives) The buffer layer composition may contain other additives within a range not impairing the effects of the present invention. Examples of other additives include antistatic agents, antioxidants, softeners (plasticizers), fillers, antirust agents, pigments, and dyes. When compounding these additives, the content of each additive in the buffer layer composition is preferably 0.01 to 6 parts by mass, more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the total amount of the energy ray polymerizable compound.

The buffer layer formed from the buffer layer composition containing an energy ray polymerizable compound can be obtained by polymerizing and hardening the buffer layer composition having the above composition by irradiation with energy rays. That is, this buffer layer is a cured product of the composition for buffer layers.

Therefore, the buffer layer preferably contains polymerized units derived from component (b1) and polymerized units derived from component (b2). In addition, the buffer layer may contain a polymerization unit derived from the component (b3), or may contain a polymerization unit derived from the component (b4). The content ratio of each polymer unit in the buffer layer is generally the same as the ratio (feed ratio) of each component constituting the buffer layer composition.

(6. Peeling sheet) A release sheet can be attached to the surface of the protective sheet for semiconductor processing. Specifically, the release sheet is attached to the surface of the adhesive layer of the protective sheet for semiconductor processing. The release sheet is attached to the surface of the adhesive layer to protect the adhesive layer during transportation and storage. The peeling sheet is attached to the peelable protective sheet for semiconductor processing, and is peeled and removed from the protective sheet for semiconductor processing before using the protective sheet for semiconductor processing (ie, before attaching the wafer).

Examples of the release sheet include those that have undergone a release treatment on at least one surface, and specifically, those that have a release agent coated on the surface of a base material for a release sheet, and the like.

As the base material for the release sheet, a resin film is preferable, and as the resin constituting the resin film, for example, polyethylene terephthalate resin, polybutylene terephthalate resin, polynaphthalate resin, Polyester resins such as ethylene glycol resins, polypropylene resins, polyolefin resins such as polyethylene resin films, and the like. Examples of release agents include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, fluorine-based Department of resin, etc.

The thickness of the release sheet is not particularly limited, but is preferably 10-200 μm, more preferably 20-150 μm.

(7. Manufacturing method of protective sheet for semiconductor processing) The method of producing the protective sheet for semiconductor processing of this embodiment is not particularly limited as long as it can form an antistatic layer, buffer layer, and adhesive layer on the main surface of the substrate, and known methods can be used. Hereinafter, a method of manufacturing the protective sheet for semiconductor processing shown in FIG. 1A will be described.

First, as a composition for forming an antistatic layer, for example, a composition for an antistatic layer containing the above components is prepared, or a composition obtained by diluting the composition for an antistatic layer with a solvent or the like. Similarly, as an adhesive layer composition for forming an adhesive layer, for example, a composition for an adhesive layer containing the above-mentioned components is prepared, or a composition obtained by diluting the composition for an adhesive layer with a solvent or the like . Similarly, as the composition for a buffer layer for forming a buffer layer, for example, a composition for a buffer layer containing the above components is prepared, or a composition obtained by diluting the composition for a buffer layer with a solvent or the like.

As the solvent, for example, methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, etc. Organic solvents.

Then, the buffer layer composition on the release treatment surface of the first release sheet is coated by spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, or gravure coating. A known method such as cloth method is applied to form a coating film, and the coating film is semi-hardened to form a buffer layer film on the release sheet. The buffer layer film formed on the release sheet was bonded to one side of the substrate, and the buffer layer film was completely cured to form a buffer layer on the substrate.

In this embodiment, the hardening of the coating film is preferably performed by irradiation of energy rays. In addition, the curing of the coating film may be performed in one curing treatment, or may be performed in plural times.

Next, the antistatic layer composition is applied to the release-treated surface of the second release sheet by a known method, followed by heating and drying to form an antistatic layer on the second release sheet. Thereafter, the second release sheet was bonded to the surface of the base material on which the antistatic layer and buffer layer were not formed, and the second release sheet was removed.

Next, the composition for an adhesive layer is apply|coated by a well-known method to the peeling process surface of a 3rd release sheet, it heat-dries, and an adhesive layer is formed on a 3rd release sheet. Afterwards, by bonding the adhesive layer on the third peeling sheet to the antistatic layer on the base material, an antistatic layer and an adhesive layer are sequentially formed on one main surface of the base material. A protective sheet for semiconductor processing with a buffer layer formed on the other main surface. In addition, the third release sheet can be removed when using the protective sheet for semiconductor processing.

(8. Manufacturing method of semiconductor device) The protective sheet for semiconductor processing of the present invention is preferably used in DBG, when it is attached to the surface of a semiconductor wafer, and the backside grinding of the wafer is performed. In particular, the protective sheet for semiconductor processing of the present invention is preferably used for LDBG in which a wafer group with a small kerf width can be obtained when semiconductor wafers are singulated.

As a non-limiting usage example of the protective sheet for semiconductor processing, a method of manufacturing a semiconductor device will be specifically described below.

Specifically, the method for manufacturing a semiconductor device includes at least the following steps 1 to 4. Step 1: a step of attaching the above-mentioned protective sheet for semiconductor processing to a semiconductor wafer. Step 2: A step of forming a groove from the surface side of the semiconductor wafer, or forming a modified region inside the semiconductor wafer from the surface or back surface of the semiconductor wafer. Step 3: Attach a protective sheet for semiconductor processing to the surface, and grind the semiconductor wafer on which the above-mentioned groove or modified region is formed from the back side, and start from the groove or modified region, and singulate it into a plurality of wafers. step. Step 4: A step of peeling off the aforementioned protective sheet for semiconductor processing from the singulated wafer (that is, wafer group).

Hereinafter, each step of the manufacturing method of the above-mentioned semiconductor device will be described in detail.

(step 1) In step 1, as shown in FIG. 2 , the main surface 30a of the adhesive layer 30 of the protective sheet 1 for semiconductor processing according to this embodiment is attached to the surface 100a of the semiconductor wafer 100 . By attaching the protective sheet for semiconductor processing to the surface of the semiconductor wafer, the surface of the semiconductor wafer can be fully protected.

This step may be performed before step 2 described later, or may be performed after step 2. For example, in the case of forming a modified region on a semiconductor wafer, step 1 is preferably performed before step 2. On the other hand, in the case where grooves are formed on the surface of the semiconductor wafer by dicing or the like, step 1 is performed after step 2 . That is, the surface of the wafer having the grooves formed in step 2 described later is affixed with a protective sheet for semiconductor processing in this step 1 .

The semiconductor wafer used in this manufacturing method may be a silicon wafer, or may be a wafer of gallium arsenide, silicon carbide, lithium tantalate, lithium niobate, gallium nitride, indium phosphorus, etc., a glass wafer, or the like. In this embodiment, the semiconductor wafer is preferably a silicon wafer.

The thickness of the semiconductor wafer before polishing is not particularly limited, but is usually about 500 to 1000 μm. In addition, semiconductor wafers typically have circuits formed on their surfaces. The formation of the circuit on the surface of the wafer can be performed by various conventional methods including etching method and lift-off method (Lift-off method).

(step 2) In step 2, grooves are formed from the surface side of the semiconductor wafer. Alternatively, the modified region is formed inside the semiconductor wafer from the front or back of the semiconductor wafer.

The groove formed in this step is shallower than the thickness of the semiconductor wafer. The grooves can be formed by dicing using a conventionally known wafer dicing device or the like. In addition, the semiconductor wafer is divided into a plurality of semiconductor wafers along the grooves in step 3 described later.

In addition, the modified region is a brittle part of the semiconductor wafer, and the semiconductor wafer is thinned by grinding in the grinding step, and the modified region of the semiconductor wafer is destroyed by the force applied by the grinding, and becomes The region where singulation becomes the starting point of a semiconductor wafer. That is, the grooves and modified regions in step 2 are formed along the dividing lines when the semiconductor wafer is divided into individual semiconductor wafers in step 3 described later.

The modified region is formed by irradiating laser light with the inside of the semiconductor wafer as a focal point, and the modified region is formed inside the semiconductor wafer. Laser irradiation may be performed from the front side of the semiconductor wafer or may be performed from the back side. In addition, in the aspect of forming the modified region, when step 2 is performed after step 1 and laser irradiation is performed from the wafer surface, the semiconductor wafer is irradiated with laser light through the protective sheet for semiconductor processing.

A semiconductor wafer on which a protective sheet for semiconductor processing is attached and on which a groove or a modified region is formed is placed on a chuck table, and is held by being adsorbed on the chuck table. At this time, the surface side of the semiconductor wafer is placed on the side of the chuck table and adsorbed.

(step 3) After Step 1 and Step 2, the back surface of the semiconductor wafer on the chuck table is ground, and the semiconductor wafer is singulated into a plurality of semiconductor wafers to obtain a wafer group.

Here, when the groove is formed on the semiconductor wafer, the back grinding is performed so that the semiconductor wafer is thinned at least to the bottom of the groove. By this back grinding, the groove becomes a notch penetrating the wafer, and the semiconductor wafer is divided by the notch to be singulated into individual semiconductor chips.

On the other hand, when the modified region is formed, the polished surface (wafer back surface) may reach the modified region by grinding, but it does not need to reach the modified region strictly. That is, it is only necessary to polish the semiconductor wafer to a position close to the modified region so that the semiconductor wafer is broken into individual semiconductor wafers starting from the modified region. For example, the actual singulation of the semiconductor wafer can be performed by attaching the pick-up tape described later and extending the pick-up tape.

In addition, after the back grinding is completed, dry polishing may be performed before the wafer is picked up.

The shape of the singulated semiconductor wafer may be square or elongated such as a rectangle. In addition, the thickness of the singulated semiconductor wafer is not particularly limited, but is preferably about 5 to 100 μm, more preferably 10 to 45 μm. According to LDBG in which a modified region is provided inside the wafer by laser, and the wafer is singulated by stress during wafer back grinding, the thickness of the singulated semiconductor wafer is likely to be 50 μm or less, more preferably 10 μm. ~45 μm. Also, the size of the singulated semiconductor wafer is not particularly limited, but the wafer size is preferably less than 600 mm ² , more preferably less than 400 mm ² , and still more preferably less than 120 mm ² .

When the protective sheet for semiconductor processing of this embodiment is used, even if it is a thin and/or small semiconductor wafer, cracks can be prevented from occurring on the semiconductor wafer during back grinding (step 3) and when the protective sheet for semiconductor processing is peeled off (step 4). , and prevent static electricity.

(step 4) Next, the protective sheet for semiconductor processing is peeled off from the singulated semiconductor wafer (that is, a plurality of semiconductor wafers). This step is performed, for example, by the following method.

In this embodiment, the adhesive layer of the protective sheet for semiconductor processing is formed of an energy ray-curable adhesive, so the energy ray is irradiated to harden and shrink the adhesive layer, so that the adherend (singulated semiconductor wafer) ) decreased adhesion. Next, a pick-up tape is attached to the back side of the singulated semiconductor wafer, and the position and direction are adjusted so that pick-up is possible. At this time, the ring frame arranged on the outer peripheral side of the wafer is also attached to the pick tape, and the outer peripheral edge portion of the pick tape is fixed to the ring frame. The pick-up tape can be attached to the wafer and the ring frame at the same time, or it can be attached at different points in time. Next, the protective sheet for semiconductor processing is peeled off from the plurality of semiconductor wafers held on the pick-up tape.

Since the protective sheet for semiconductor processing of this embodiment has the above-mentioned characteristics, even if the peeling speed when peeling the protective sheet for semiconductor processing from the semiconductor wafer is fast, no paste residue will be generated on the semiconductor wafer, etc., and the wafer can be suppressed. They are in contact with each other and can be peeled off while suppressing static electricity.

Thereafter, a plurality of semiconductor wafers on the pick-up tape are picked up, fixed on a substrate or the like, and a semiconductor device is manufactured.

In addition, the pick-up tape is not particularly limited, but is, for example, composed of an adhesive sheet including a base material and an adhesive layer provided on one surface of the base material.

As mentioned above, the protective sheet for semiconductor processing of the present invention has been described for an example using a method of singulating semiconductor wafers by DBG or LDBG. When it is round, it can be preferably used in LDBG to obtain a smaller kerf width and a thinner wafer group.

As mentioned above, although embodiment of this invention was demonstrated, this invention is not limited to any of said embodiment, It can change in various aspects within the range of this invention. [Example]

Hereinafter, the invention will be described in more detail using examples, but the present invention is not limited to these examples.

The measurement methods and evaluation methods in this example are as follows.

(90ﾟPeel adhesion of the adhesive layer before and after energy ray hardening) The protective sheets for semiconductor processing produced in Examples and Comparative Examples were cut to a width of 25 mm and used as test pieces. Attach the adhesive layer of the test piece to the mirror silicon wafer without the circuit surface with a roller with a mass of 2 kg. After standing for 1 hour, according to JIS Z 0237, the test piece was peeled at a peeling speed of 600mm/min so as to become 90ﾟ to the mirror surface silicon wafer, and the adhesion was measured (90ﾟ peeling adhesion of the adhesive layer before energy ray hardening ).

In addition, the adhesive layer of another test piece was attached to the mirror surface silicon wafer with the roller of mass 2kg. The adhesive layer of the test piece was irradiated with ultraviolet rays from the substrate side of the protective sheet for semiconductor processing under the conditions of illuminance 20mW/cm ² and light intensity 380mJ/cm ² to harden the adhesive layer. According to JIS Z 0237, The test piece was peeled off at a peeling speed of 600 mm/min so as to become 90ﾟ to the mirror surface silicon wafer, and the adhesive force (90ﾟ peeling adhesive force of the adhesive layer after energy ray curing) was measured.

(Surface resistivity of adhesive layer after energy ray hardening) The protective sheets for semiconductor processing produced in Examples and Comparative Examples were cut into a size of 10 cm×10 cm, and the adhesive layer of the protective sheet for semiconductor processing was irradiated with ultraviolet rays to be cured. According to JIS K 7194, the surface resistivity of the adhesive layer after hardening was measured with Advantest surface resistivity meter R8252 under the condition of 23 degreeC50%RH, and the applied voltage of 100V.

(Peel static voltage of protective sheet for semiconductor processing) The protective sheets for semiconductor processing made in Examples and Comparative Examples were attached to the surface of silicon wafers, and a wafer mounter (wafer mounter) (product name "RAD-2700F/12", manufactured by Lintec) was used. While peeling off the protective sheet for semiconductor processing from the silicon wafer at a peeling speed of 600mm/min and a temperature of 40°C, use a peeling electrostatic tester PFM-711A made by Prostat, with a distance of 10mm from the peeling surface side of the wafer surface and adhesive layer The voltage was measured at the place where the wafer was placed, and the voltage value on the wafer side was taken as the peeling static voltage value. In this example, it was judged that the sample whose peeling electrostatic voltage was 500 V or less was good.

(crack occurrence rate) The protective sheets for semiconductor processing produced in Examples and Comparative Examples were attached to a 12-inch-diameter, 775-μm-thick protective sheet using a tape laminator for back grinding (manufactured by Lintec Corporation, device name "RAD-3510F/12"). silicon wafer. Using a laser saw (manufactured by DISCO, device name "DFL7361"), a lattice-shaped modified region was formed on the wafer. In addition, the grid size is 10 mm×10 mm.

Next, using a back grinding device (manufactured by DISCO, device name "DGP8761"), grinding (including dry polishing) was performed until the thickness became 30 μm, and the wafer was singulated into a plurality of wafers.

After the polishing step, energy ray (ultraviolet) irradiation was performed, and a dicing tape (manufactured by Lintec, Adwill D-175) was attached to the opposite side of the attached surface of the protective sheet for semiconductor processing, and then the protective sheet for semiconductor processing was peeled off. Thereafter, the singulated wafers were observed with a digital microscope (product name "VHX-1000", manufactured by KEYENCE Co., Ltd.), wafers with cracks were counted, and the size of each crack was classified according to the following criteria. In addition, the size (μm) of the crack is the larger value between the length (μm) of the crack along the longitudinal direction of the wafer and the length (μm) of the crack along the lateral direction of the wafer. (baseline) Large fissures: the size of the fissure exceeds 50 μm. Medium crack: The size of the crack is 20 μm or more and 50 μm or less. Small cracks: the size of cracks is less than 20 μm.

In addition, the crack occurrence rate (%) was calculated based on the following formula. The rate of occurrence of cracks is 2.0% or less, the number of large cracks is 0, the number of medium cracks is 10 or less, and the number of small cracks is 20 or less. ". Crack occurrence rate (%)=(Number of wafers with cracks/Number of total wafers)×100

(Example 1) (1) Adhesive layer (Preparation of composition for adhesive layer) Copolymerize 65 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA) and 2- An acrylic polymer obtained by 15 parts by mass of hydroxyethyl ester (2HEA) was reacted with 2-methacryloxyethyl isocyanate (MOI) to obtain an energy ray-curable acrylic resin (Mw: 500,000). To 100 parts by mass of this energy ray-curable acrylic resin, 6 parts by mass of energy ray-curable compound polyfunctional urethane acrylate (trade name. Unisplendour UT-4332, manufactured by Mitsubishi Chemical Co., Ltd.), An isocyanate-based crosslinking agent (manufactured by TOSOH Co., Ltd., trade name: CORONATE L) is 0.375 parts by mass based on solid content, and is composed of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. The coating liquid of the composition for adhesive agent layers was prepared by diluting 1 mass part of polymerization initiators with a solvent.

(formation of adhesive layer) On the release-treated surface of a release sheet (manufactured by Lintec Corporation, trade name "SP-PET381031", silicone release-treated polyethylene terephthalate (PET) film, thickness: 38 μm), apply The solution of the above-mentioned adhesive composition was dried, and an adhesive layer-attached release sheet having an adhesive layer having a thickness of 20 μm was produced.

(2) Production with antistatic layer As a substrate, a primer-coated PET film (manufactured by Toyobo Co., Ltd., trade name "PET50A-4100") having a thickness of 50 μm provided with a primer layer (first primer layer) on one side was prepared. The Young's modulus of this PET film was 2500 MPa.

On the side opposite to the side where the PET film is provided with the first primer layer, apply a polythiophene-based conductive polymer (manufactured by Nagase Chemtech Co., Ltd., Denatron P-400MP), and dry it to form a thickness on the PET film. 120nm antistatic layer.

(3) buffer layer (Synthesis of urethane acrylate oligomer (UA-1)) The terminal isocyanate urethane prepolymer obtained by reacting polyester diol with isophorone diisocyanate is reacted with 2-hydroxyethyl acrylate to obtain a bifunctional urethane with a weight average molecular weight (Mw) of 5000 Acrylate-based oligomer (UA-1).

(Preparation of buffer layer forming composition) As an energy ray polymerizable compound, 40 parts by mass of the urethane acrylate oligomer (UA-1) synthesized above, 40 parts by mass of isobornyl acrylate (IBXA), and phenylhydroxypropyl acrylate (HPPA ) 20 parts by mass, and further deploy 2.0 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by IGM Resins, product name "OMNIRAD184") as a photopolymerization initiator and 0.2 parts by mass of phthalocyanine pigments to prepare a buffer layer Forming compositions.

(formation of buffer layer) On the release-treated surface of a release sheet (manufactured by Lintec Corporation, trade name "SP-PET381031", silicone release-treated polyethylene terephthalate (PET) film, thickness: 38 μm), apply The above buffer layer forming composition forms a coating film. Then, the coating film was irradiated with ultraviolet rays to semi-harden the coating film to form a buffer layer-forming film with a thickness of 50 μm.

In addition, the above-mentioned ultraviolet irradiation was carried out using a belt conveyor type ultraviolet irradiation device (product name "ECS-401GX", manufactured by EYE GRAPHICS Co., Ltd.) and a high-pressure mercury lamp (H04-L41 manufactured by EYE GRAPHICS Co., Ltd.: H04-L41), with a lamp height of 150 mm, The lamp output was 3 kW (converted output 120 mW/cm), the illuminance of light wavelength 365 nm was 120 mW/cm ² , and the irradiation conditions were 100 mJ/cm ² .

The surface of the formed buffer layer-forming film is bonded to the first primer layer of the base material with an antistatic layer, and ultraviolet rays are irradiated again from the side of the release sheet on the buffer layer-forming film to completely harden the buffer layer-forming film to form a thickness 50 μm buffer layer.

In addition, the above-mentioned ultraviolet radiation was irradiated using the above-mentioned ultraviolet radiation device and high-pressure mercury lamp under the irradiation conditions of lamp height 150 mm, lamp output 3 kW (converted output 120 mW/cm), illuminance of light wavelength 365 nm 160 mW/cm ² , and irradiation dose 500 mJ/cm ² next.

(4) Preparation of protective sheet for semiconductor processing By laminating the antistatic layer and the adhesive layer of the release sheet with an adhesive layer, the antistatic layer and the adhesive layer are sequentially formed on one main surface of the substrate, and the other side of the substrate is formed. A protective sheet for semiconductor processing with a buffer layer formed on the main surface.

(Example 2) A protective sheet for semiconductor processing was obtained by the same method as in Example 1 except that the thickness of the antistatic layer was 150 nm and the thickness of the adhesive layer was 5 μm.

(Example 3) Except having made the thickness of the antistatic layer into 80 nm and the thickness of the adhesive layer into 200 micrometers, the protective sheet for semiconductor processing was obtained by the method similar to Example 1.

(Example 4) Except having formed the adhesive layer using the following composition for adhesive layers, the protective sheet for semiconductor processing was obtained by the method similar to Example 1.

(Preparation of composition for adhesive layer) 89 parts by mass of n-butyl acrylate (BA), 8 parts by mass of methyl methacrylate (MMA) and 3 parts by mass of 2-hydroxyethyl acrylate (2HEA) were copolymerized to obtain an acrylic polymer (Mw: 800,000 ).

With respect to 100 parts by mass of the above-mentioned acrylic polymer, 1 part by mass (solid content) of a toluene diisocyanate-based crosslinking agent (TOSOH, product name "CORONATE L") as a crosslinking agent, an epoxy-based crosslinking agent (1 , 3-bis(N,N-diglycidylaminomethyl)cyclohexane) 2 parts by mass (solid content), energy ray-curing compound (manufactured by Mitsubishi Chemical Corporation, product name "Ultraviolet UV-3210EA" ) 45 parts by mass (solid content) and photopolymerization initiator (manufactured by IGM Resins, product name "OMNIRAD184") 1 mass part (solid content), diluted with a solvent to obtain a coating liquid of a composition for an adhesive layer .

(Example 5) Except for using the following composition for an adhesive layer to form an adhesive layer, the thickness of the antistatic layer is set to 25 nm, and the thickness of the adhesive layer is set to 5 μm, by the same method as in Example 1, a protective film for semiconductor processing was obtained. piece.

(Preparation of composition for adhesive layer) 75 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA) and 2-hydroxyethyl acrylate were added to 90 mole % of all hydroxyl groups in the acrylic polymer. An acrylic polymer obtained by copolymerizing 5 parts by mass of ester (2HEA) was reacted with 2-methacryloxyethyl isocyanate (MOI) to obtain an energy-ray-curable acrylic resin (Mw: 500,000).

Here, 100 parts by mass of an energy-ray-curable acrylic resin was added with an isocyanate-based crosslinking agent (TOSOH, trade name "CORONATE L") at a solid content basis of 0.375 parts by mass, prepared from bis(2,4,6-trimethyl 1 mass part of the photoinitiator which consists of benzoyl) phenyl phosphine oxide was diluted with the solvent, and the coating liquid of the composition for adhesive agent layers was prepared.

(comparative example 1) Except not providing an antistatic layer, by the same method as Example 1, the protective sheet for semiconductor processing was obtained.

(comparative example 2) A protective sheet for semiconductor processing was obtained by the same method as in Example 1, except that the adhesive layer was formed using the following composition for an adhesive layer, and the thickness of the antistatic layer was 50 nm.

(Preparation of composition for adhesive layer) 65 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA) and 2-hydroxyethyl acrylate were added to 90 mole % of all hydroxyl groups in the acrylic polymer. An acrylic polymer obtained by copolymerizing 15 parts by mass of ester (2HEA) was reacted with 2-methacryloxyethyl isocyanate (MOI) to obtain an energy ray-curable acrylic resin (Mw: 500,000).

Here, to 100 parts by mass of energy ray-curable acrylic resin, 20 parts by mass of energy ray-curable compound polyfunctional urethane acrylate (trade name: Unisplendour UT-4332, manufactured by Mitsubishi Chemical Corporation), 20 parts by mass of isocyanate A cross-linking agent (TOSOH, trade name "CORONATE L") based on solid content of 0.375 parts by mass, a photopolymerization initiator formed from bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide 1 part by mass of the agent was diluted with a solvent to prepare a coating liquid of a composition for an adhesive layer.

(comparative example 3) Except having formed the adhesive layer using the following composition for adhesive layers, the protective sheet for semiconductor processing was obtained by the method similar to Example 1.

(Preparation of composition for adhesive layer) 75 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA) and 2-hydroxyethyl acrylate were added to 50 mole % of the hydroxyl groups in the total hydroxyl groups of the acrylic polymer. An acrylic polymer obtained by copolymerizing 5 parts by mass of ester (2HEA) was reacted with 2-methacryloxyethyl isocyanate (MOI) to obtain an energy-ray-curable acrylic resin (Mw: 500,000).

Here, 100 parts by mass of an energy-ray-curable acrylic resin was added with an isocyanate-based crosslinking agent (TOSOH, trade name "CORONATE L") at a solid content basis of 0.375 parts by mass, prepared from bis(2,4,6-trimethyl 1 mass part of the photoinitiator which consists of benzoyl) phenyl phosphine oxide was diluted with the solvent, and the coating liquid of the composition for adhesive agent layers was prepared.

[Table 1] Protective sheet for semiconductor processing evaluate adhesive layer Antistatic layer Peeling electrostatic voltage (wafer side) (V) Crack incidence determination 90°adhesion before UV (N/25mm 90°adhesion after UV (N/25mm) Adhesion ratio after UV/before UV (%) Surface resistance (Ω/cm ² ) Thickness (μm) Thickness (nm) Example 1 10.8 0.06 0.6 2.1×10 ¹³ 20 120 100 good ○ Example 2 5.3 0.05 0.9 6.0×10 ¹² 5 150 50 good ○ Example 3 18.5 0.14 0.8 8.9×10 ¹⁴ 200 80 200 good ○ Example 4 3.3 0.13 3.9 5.6×10 ¹² 20 120 50 good ○ Example 5 6.2 0.22 3.5 9.3×10 ¹⁴ 5 25 450 good ○ Comparative example 1 10.8 0.06 0.6 1.3×10 ¹⁵ 20 0 4300 good x Comparative example 2 11.2 0.03 0.3 1.1×10 ¹⁵ 20 50 3300 good x Comparative example 3 13.0 1.83 14.1 7.5×10 ¹¹ 20 120 40 bad x

The above measurement and evaluation were performed on the obtained samples (Examples 1 to 5 and Comparative Examples 1 to 3). The adhesive force ratio was calculated from the 90ﾟ peel adhesive force of the adhesive layer before and after energy ray hardening. The results are shown in Table 1.

According to Table 1, when the 90ﾟ peeling adhesive force of the adhesive layer of the protective sheet for semiconductor processing is within the above range, and the antistatic layer is included in the protective sheet for semiconductor processing, it is confirmed that the protective sheet for semiconductor processing is accompanied by peeling. The static voltage is low, and further, the occurrence rate of cracks due to wafer shift is low.

1: Protective sheet for semiconductor processing 10: Substrate 10a: main surface 10b: main surface 20: Antistatic layer 30: Adhesive layer 30a: surface 40: buffer layer 100: Wafer 100a: surface 100b: back

FIG. 1A is a schematic cross-sectional view showing an example of a protective sheet for semiconductor processing according to this embodiment. FIG. 1B is a schematic cross-sectional view showing another example of the protective sheet for semiconductor processing according to this embodiment. FIG. 2 is a schematic cross-sectional view showing how the protective sheet for semiconductor processing according to the present embodiment is attached to the circuit surface of the wafer.

1: Protective sheet for semiconductor processing

10: Substrate

10a: main surface

10b: main surface

20: Antistatic layer

30: Adhesive layer

30a: surface

40: buffer layer

Claims (7)

A protective sheet for semiconductor processing, comprising: Base material, antistatic layer, energy ray curable adhesive layer, and buffer layer, Adhesive force of 0.035N/25mm when the adhesive layer cured by energy rays is peeled from the silicon wafer at a peeling speed of 600mm/min at an angle of 90ﾟ between the adhesive layer and the silicon wafer More than, less than 0.15N/25mm. The protective sheet for semiconductor processing according to Claim 1, wherein the adhesive layer hardened by energy rays is peeled at a speed of 600mm/min, from the silicon wafer at an angle formed between the aforementioned adhesive layer and the aforementioned silicon wafer. The adhesive force when peeling off in a 90ﾟ method is 90ﾟ from the silicon wafer at a peeling speed of 600mm/min with respect to the adhesive layer before hardening the adhesive layer and the silicon wafer. The adhesive force ratio when peeled off by the method is 4% or less. The protective sheet for semiconductor processing according to claim 1 or 2, wherein the surface resistivity of the adhesive layer after energy ray curing is 5.1×10 ¹² Ω/cm ² or more and 1.0×10 ¹⁵ Ω/cm ² or less. The protective sheet for semiconductor processing according to any one of claims 1 to 3, wherein the Young's modulus of the base material is 1000 MPa or more. The protective sheet for semiconductor processing according to any one of claims 1 to 4, wherein the protective sheet for semiconductor processing has the following structure: the adhesive layer is provided on one main surface of the substrate, and the adhesive layer is provided on the substrate. The aforementioned antistatic layer is provided between the material and the aforementioned adhesive layer, and the aforementioned buffer layer is disposed on the other main surface of the aforementioned substrate; or, the aforementioned adhesive layer is provided on one main surface of the aforementioned substrate, and the aforementioned The aforementioned antistatic layer and the aforementioned buffer layer are arranged between the substrate and the aforementioned adhesive layer. The protective sheet for semiconductor processing according to any one of Claims 1 to 5, wherein the wafer is single-layered by grinding the back surface of the wafer with the groove formed on the surface or the modified region formed inside. In the step of bulking into a wafer, it is used by sticking to the surface of the wafer. A method of manufacturing a semiconductor device, comprising the steps of: Attaching the protective sheet for semiconductor processing as described in any one of Claims 1 to 6 on the surface of the wafer; A step of forming a groove from the surface side of the aforementioned wafer, or forming a modified region inside the aforementioned wafer from the surface or back surface of the aforementioned wafer; Attaching the aforementioned protective sheet for semiconductor processing to the surface, and grinding the wafer with the aforementioned groove or the aforementioned modified region formed thereon from the back side, and using the aforementioned groove or the aforementioned modified region as a starting point, and singulating it into a plurality of wafers; From the singulated wafer, the aforementioned protective sheet for semiconductor processing was peeled off.

Images