JP5242830B1 - Adhesive tape for protecting semiconductor wafer surface and method for producing semiconductor wafer - Google Patents

Abstract

Provided are a semiconductor wafer surface protecting pressure-sensitive adhesive tape and a method for producing a semiconductor wafer that can be firmly adhered to a semiconductor wafer during processing of the semiconductor wafer, and can be removed without damaging the semiconductor wafer or leaving no adhesive residue at the time of peeling.
The substrate film has at least one radiation-curable pressure-sensitive adhesive layer, has the following curing shrinkage value S of 2.0 or less, and has an adhesive force A before irradiation to a polished surface of stainless steel. Is 1.5 to 20 N / 25 mm, and the adhesive strength B after radiation irradiation is 0.01 to 1.5 N / 25 mm, and a method for producing a semiconductor wafer surface protecting adhesive tape and a semiconductor wafer .
Curing shrinkage value S = {(B / A) / (D / C)}
A represents the adhesive strength before radiation irradiation to the polished surface of stainless steel, B represents the adhesive strength after radiation irradiation to the polished surface of stainless steel, C represents the tack force before radiation irradiation on the adhesive tape surface, and D represents It represents the tack force after irradiation on the adhesive tape surface.
[Selection figure] None

Description

  The present invention relates to an adhesive tape for protecting a semiconductor wafer surface and a method for producing a semiconductor wafer. More specifically, the present invention relates to a semiconductor wafer surface protecting adhesive tape that can be applied to a back grinding process of a semiconductor wafer having irregularities on its surface, and a method for manufacturing a semiconductor wafer.

  In the manufacturing process of a semiconductor wafer, a wafer after pattern formation is usually subjected to processing such as back grinding and etching in order to reduce its thickness. At this time, for the purpose of protecting the pattern on the surface of the semiconductor wafer, an adhesive tape for protecting the surface of the semiconductor wafer is attached to the pattern surface. Generally, a pressure-sensitive adhesive tape for protecting a semiconductor wafer surface is formed by laminating a pressure-sensitive adhesive layer on a base film, and the pressure-sensitive adhesive layer is attached to the surface of a semiconductor wafer.

  In recent years, with the miniaturization and high functionality of mobile phones and personal computers, flip chip mounting that can be mounted in a smaller space than wire bonding has been developed. In the flip chip mounting, when the chip surface and the substrate are electrically connected, they are connected by ball-shaped or cylindrical bumps formed on the surface of the semiconductor wafer. In the back-grinding process of the semiconductor wafer with the bumps formed in this way, there is a risk that a seapage will occur that the cutting water enters between the semiconductor wafer and the adhesive tape and contaminates the semiconductor wafer due to the shape of the semiconductor wafer. Therefore, stronger adhesion between the semiconductor wafer and the pressure-sensitive adhesive tape is required. However, when the adhesion is increased, the peelability of the pressure-sensitive adhesive tape is deteriorated. In particular, the thickness of the semiconductor wafer tends to be thinner, and it is not uncommon to process the semiconductor wafer to a thickness of 100 μm or less.

  In order to solve this problem, it has been proposed to use a radiation curable pressure-sensitive adhesive to reduce the adhesive strength when peeling the semiconductor wafer surface protecting pressure-sensitive adhesive tape (see, for example, Patent Document 1).

JP 2010-215769 A

  However, with conventional radiation-curing adhesive tape, when radiation-cured, the adhesive bites into the bumps and other irregularities on the surface of the semiconductor wafer, the anchor effect becomes stronger, and it may be difficult to peel off. There has been a problem that the adhesive is left on the surface of the semiconductor wafer after the part is broken or peeled off. This problem becomes more conspicuous as the bumps become higher and the pitch between bumps becomes narrower for the purpose of improving the reliability of the semiconductor.

  Accordingly, the present invention provides an adhesive tape for protecting a semiconductor wafer surface and a semiconductor using the same, which can be firmly adhered to a semiconductor wafer during processing of the semiconductor wafer and can be peeled off without being damaged or having adhesive residue at the time of peeling. It is an object to provide a method for manufacturing a wafer.

In view of the above problems, the present inventors have conducted intensive studies and found that the adhesive strength and curing shrinkage value before and after radiation irradiation are important, and further studies have been made to complete the present invention. is there.
That is, the said subject was achieved by the following means.
(1) An adhesive tape for surface protection used when being bonded to a semiconductor wafer and ground on the back surface,
It has at least one radiation-curable pressure-sensitive adhesive layer on the base film, has the following curing shrinkage value S of 0.3 to 1.8 , and has an adhesive force A before irradiation of radiation on the polished surface of stainless steel. a 1.5~20N / 25mm, and the adhesive strength B after radiation irradiation 0.01~1.5N / 25mm der is, the lamination surface side of the semiconductor wafer surface protecting adhesive tape of the semiconductor wafer maximum difference in height between the bottom of the top portion of the irregularities present on the surface is a 10 to 300 [mu] m, the semiconductor wafer surface thickness of the radiation curable adhesive layer is characterized 1~30μm der Rukoto Protective adhesive tape.

          Curing shrinkage value S = {(B / A) / (D / C)}

(In the above, A represents the adhesive strength before irradiation with respect to the polished surface of stainless steel, B represents the adhesive strength after irradiation with respect to the polished surface of stainless steel, and C represents the tack force before irradiation on the adhesive tape surface ( Peak value), and D represents the post-irradiation tack force (peak value) on the adhesive tape surface.)
(2) A radiation non-curable adhesive having a storage elastic modulus of 1 × 10 ⁴ to 1 × 10 ⁶ Pa at 25 ° C. or 60 ° C. in a laminator between the base film and the radiation-irradiating pressure-sensitive adhesive layer. The adhesive tape for protecting a semiconductor wafer surface according to (1), comprising an intermediate layer composed of an agent layer or a resin.
(3) total thickness of layers present in the radiation-curable pressure-sensitive adhesive layer side of the substrate film having found the maximum difference in height between the bottom of the top portion of the irregularities present on the semiconductor wafer surface It is the above, The adhesive tape for surface protection of a semiconductor wafer as described in (1) or (2) characterized by the above-mentioned.
(4) A method for producing a semiconductor wafer, comprising the steps of: protecting a wafer surface of a semiconductor wafer with a surface protecting adhesive tape having an adhesive layer on a base film; and grinding the back surface of the wafer to process the semiconductor wafer. Because
The pressure-sensitive adhesive tape for surface protection has at least one radiation-curing pressure-sensitive adhesive layer on the base film, has the following curing shrinkage value S of 0.3 to 1.8 , and radiation on the polished surface of stainless steel adhesion a before irradiation a 1.5~20N / 25mm, and the adhesive strength B is 0.01~1.5N / 25mm der after irradiation is, the semiconductor wafer the semiconductor wafer surface protecting adhesive tape a maximum difference in height between the bottom of the top portion of the irregularities present on the surface of the lamination surface side 10 to 300 [mu] m, the thickness of the radiation-curable pressure-sensitive adhesive layer, wherein 1~30μm der Rukoto A method for manufacturing a semiconductor wafer.

          Curing shrinkage value S = {(B / A) / (D / C)}

(In the above, A represents the adhesive force before irradiation with respect to the polished surface of stainless steel, B represents the adhesive force after irradiation with respect to the polished surface of stainless steel, and C represents the tack force before irradiation on the surface of the adhesive tape. And D represents the tack force after radiation irradiation on the adhesive tape surface.)
(5) The surface-protective pressure-sensitive adhesive tape has a storage elastic modulus at 25 ° C. or 60 ° C. of 1 × 10 ⁴ to 1 × 10 ⁶ Pa in a laminator between the base film and the radiation-irradiating pressure-sensitive adhesive layer. The method for producing a semiconductor wafer according to (4), comprising an intermediate layer composed of a radiation non-curing pressure-sensitive adhesive layer or a resin.
(6) the total thickness of the layers present in said radiation-curable pressure-sensitive adhesive layer side of the substrate film having found the maximum difference in height between the bottom of the top portion of the irregularities present on the semiconductor wafer surface The method for producing a semiconductor wafer according to (4) or (5), which is as described above.

  According to the present invention, when a semiconductor wafer is processed, the adhesive tape and the semiconductor for protecting the surface of the semiconductor wafer, which can be peeled off without causing breakage of the semiconductor wafer or leaving adhesive residue, can be significantly reduced by firmly adhering to the semiconductor wafer. A method for manufacturing a wafer can be provided.

  Hereinafter, embodiments of the present invention will be described in detail.

<< Semiconductor wafer surface protective adhesive tape >>
In the pressure-sensitive adhesive tape for protecting a semiconductor wafer surface of the present invention, a radiation curable pressure-sensitive adhesive layer is formed on at least one surface of a base film.
Here, the radiation curable pressure-sensitive adhesive layer is cured by irradiation with radiation [for example, ionizing radiation such as ultraviolet rays (including laser rays) and electron beams], and the irradiation radiation is preferably ultraviolet rays.

<Curing shrinkage value>
The adhesive tape for protecting a semiconductor wafer surface of the present invention has a curing shrinkage value S of 0.3 to 1.8 . By setting the curing shrinkage value S to 0.3 to 1.8 , the generation of the anchor effect due to the biting of the adhesive into the semiconductor wafer surface is suppressed, and the adverse effect on the peelability is suppressed.
Here, the curing shrinkage value S is obtained by the following formula.

          Curing shrinkage value S = {(B / A) / (D / C)}

  In the formula, A represents the adhesive strength before irradiation with respect to the polished surface of stainless steel (Steel Use Stainless, SUS), B represents the adhesive strength after irradiation with respect to the polished surface of stainless steel, and C represents the adhesive tape surface. The tack force before radiation irradiation is represented, and D represents the tack force after radiation irradiation on the adhesive tape surface.

In the present invention, the curing shrinkage value S is 1 . 5 or less is more preferable, and 1.0 or less is more preferable.

Adhesive strength and tack strength can be obtained by the following measurements.
In addition, stainless steel (Steel Use Stainless, SUS) is a SUS304 steel plate prescribed | regulated to JISG4305, and is a thing of a mirror surface finish, or what was polished with the abrasive paper. The polishing method is finished in accordance with JIS Z 0237, and the abrasive paper having a roughness of 280 is used.

[Measurement of adhesive strength]
A test piece having a width of 25 mm and a length of 300 mm is cut out from the adhesive tape for processing a semiconductor wafer. The test piece is reciprocated three times on a 2 kg rubber roller on a 1.5 mm-thick stainless steel (Steel Use Stainless, SUS) plate specified in JIS G 4305 finished with 280 No. 280 water-resistant abrasive paper specified in JIS R 6253. Tensile tester conforming to JIS B 7721 whose measured value falls within the range of 15 to 85% of its capacity after being subjected to crimping and standing for 1 hour [for example, tensile tester manufactured by Instron (twin column desktop model 5567) ] Is used to measure the adhesive strength A before irradiation. Similarly, after 1 hour has passed after the pressure-sensitive adhesive tape has been pressure-bonded, 1000 mJ / cm ² (illuminance: 40 mW / cm ² ) is irradiated from the back surface of the base film of the pressure-sensitive adhesive tape, left for 1 hour, and then irradiated with radiation. The adhesive strength B of is measured. The measurement is performed by a 180 ° peeling method under the conditions of a pulling speed of 300 mm / min, 25 ° C., and a relative humidity of 50%. The measurement is performed three times for each adhesive tape, and the arithmetic average value is obtained. And

[Measurement of tack force]
A test piece having a width of 25 mm and a length of 150 mm is cut out from the semiconductor wafer processing adhesive tape. Using a tacking tester (for example, trade name: TACII, manufactured by Resca), a 3 mmφ cylindrical probe is pushed into the adhesive layer side to be bonded to the surface of the semiconductor wafer at a speed of 30 mm / min, and a stop load of 100 gf is applied for 1 second. The peak load when pulling up at a speed of 600 mm / min after holding is defined as tack force C before radiation irradiation. After cutting out the test piece, 1000 mJ / cm ² of ultraviolet light (illuminance: 40 mW / cm ² ) is irradiated from the back of the base film, and the test piece is left for 1 hour, and the tack force D after irradiation is obtained in the same manner. . The measurement is performed under the conditions of 25 ° C. and relative humidity of 50%, and five different points are measured in each test piece of each adhesive tape, the arithmetic average value is obtained, and this is taken as the tack force.

The adhesion between the SUS steel plate and the adhesive tape is mainly contributed by physical action (Van der Waals force, etc.), chemical action (chemical bond between interfaces) and mechanical action (anchor effect).
When the pressure-sensitive adhesive tape is cured with radiation, the radiation-curable pressure-sensitive adhesive becomes highly elastic and low-polarized, and the above-mentioned action is reduced, so that the pressure-sensitive adhesive tape can be peeled smoothly. However, since the adhesive tape shrinks during radiation curing, the anchor effect may increase when the adhesive bites into the fine irregularities of the polished SUS steel sheet.
On the other hand, the tack force represents the ease of instantaneous bonding and is not easily affected by the anchor effect.
Therefore, when the curing shrinkage value S is 0.3 to 1.8 , it is possible to peel more smoothly even on a surface having irregularities such as bumps.

<Adhesive strength>
In the adhesive tape for protecting a semiconductor wafer surface of the present invention, the adhesive strength B after radiation curing measured above is 0.01 to 1.5 N / 25 mm at 25 ° C.
In addition, it is preferable for the objective of hardening that the adhesive force B after radiation curing is lower than the adhesive force A before the radiation curing mentioned later.
The adhesive strength B after radiation curing is preferably 0.01 to 1.0 N / 25 mm.
Here, in recent years, at the time of peeling of the pressure-sensitive adhesive tape, for example, heating at about 50 ° C. is sometimes performed. In such a case, it is desirable that the temperature at the time of peeling satisfies the above range.

By setting the adhesive force B after radiation curing to 0.01 to 1.5 N / 25 mm, it is possible to reduce the risk that the adhesive remains on the surface of the semiconductor wafer or peels off the bumps on the surface of the semiconductor wafer. If the adhesive strength B after radiation curing exceeds 1.5 N / 25 mm, such an effect cannot be obtained. On the other hand, if it is less than 0.01 N / 25 mm, the tape floats before peeling, and in some cases, the tape may curl and a peeling error may occur.
Thus, by setting the adhesive force B after radiation curing to 0.01 to 1.5 N / 25 mm, there is an effect of suppressing breakage of the semiconductor wafer and adhesive residue when the semiconductor wafer is peeled off.

In the adhesive tape for protecting a semiconductor wafer surface of the present invention, the adhesive strength A before radiation curing measured above is 1.5 to 20 N / 25 mm at 25 ° C.
If the adhesive strength A before radiation curing is less than 1.5 N / 25 mm, the adhesion to the surface irregularities of the semiconductor wafer will be reduced, causing dust intrusion during semiconductor wafer grinding and lifting of the adhesive tape from the semiconductor wafer surface. Conversely, if it exceeds 20 N / 25 mm, the adhesiveness is too strong, so it is difficult to reduce the adhesive force even in radiation curing. If the radiation curing is strengthened, the anchor effect will be increased by the curing shrinkage. .

  In the present invention, the adhesive strength A before radiation curing is preferably 1.5 to 15 N / 25 mm, more preferably 2 to 15 N / 25 mm, and further preferably 2 to 10 N / 25 mm. The adhesive strength B after radiation curing is preferably 0.01 to 1.0 N / 25 mm, more preferably 0.05 to 1.0 N / 25 mm, and still more preferably 0.1 to 1.0 N / 25 mm.

<Tacking power>
In the present invention, the tack force C before radiation curing is preferably 50 to 600 kPa, more preferably 100 to 300 kPa, because of workability at the time of bonding to a semiconductor wafer. Moreover, the tack force D after radiation curing is preferably 3 to 100 kPa.

  The curing shrinkage value S can be within the scope of the present invention by appropriately adjusting the molecular weight of the pressure-sensitive adhesive composition, the type and amount of the additive, the thickness of the radiation-curable pressure-sensitive adhesive layer, and the like, as will be described later.

  Below, each component of the adhesive tape for semiconductor wafer surface protection which satisfy | fills the said hardening shrinkage value, adhesive force, and tack force is demonstrated in detail.

<Base film>
The base film is preferably made of a resin film, and known plastics, rubbers and the like can be used. For example, polyolefin resin (polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid Α-olefin homopolymers or copolymers such as methyl copolymers, ethylene-acrylic acid copolymers, ionomers, or mixtures thereof), polyester resins (polyethylene terephthalate, polyethylene naphthalate), polycarbonate resins, polyurethane resins Engineering plastics (polymethyl methacrylate, etc.), synthetic rubbers (styrene-ethylene-butene or pentene copolymers), thermoplastic elastomers (polyamide-polyol copolymers, etc.), and mixtures thereof Thing, and the like. Moreover, you may use what made these two or more layers.
In the present invention, the base film is preferably a polyolefin resin, and more preferably an ethylene-vinyl acetate copolymer film.

The thickness of the base film is 50 to 300 μm if it is a base material having flexibility such as polyethylene, and has rigidity such as polyester, from the viewpoints of high elongation characteristics, peelability of the surface protection tape, and cutability in the bonding machine. If it is a base material, 10-100 micrometers is suitable.
In this invention, 50-300 micrometers is preferable.

<Intermediate layer>
As a method of preventing grinding dust intrusion when performing backgrinding of a semiconductor wafer having irregularities on the surface, a method of causing the adhesive tape to follow the irregularities on the entire surface of the wafer and a method of adhering the adhesive tape only to the periphery of the semiconductor wafer Can be considered. In the former method, if the radiation curing type adhesive is to have a function to follow the unevenness, the thickness of the adhesive should be equal to or greater than the unevenness on the surface of the semiconductor wafer, resulting in increased curing shrinkage and poor peeling. It becomes the cause of. On the other hand, when the thickness of the pressure-sensitive adhesive layer is reduced, and it is attempted to follow the unevenness with a single-layer base film, it is necessary to make a low-elastic base film whose storage elastic modulus is less than 1 × 10 ⁶ Pa. When such a low-elasticity film is used, there is a concern that the flat holding power of the thinned semiconductor wafer after backgrinding is inferior and the productivity of the adhesive tape is deteriorated.
In this invention, in order to solve such a problem, it is desirable to have an intermediate | middle layer with an uneven | corrugated followable | trackability between a base film and a radiation curable adhesive layer.
Here, the intermediate layer is a layer between the base film and the radiation curable pressure-sensitive adhesive layer, and this intermediate layer may be a simple resin layer or resin film (non-adhesive resin layer or resin film). It may be a radiation non-curing pressure-sensitive adhesive layer. Further, a plurality of intermediate layers may be provided.
When the intermediate layer is a resin layer or a resin film, a known resin film can be used. When the intermediate layer is a radiation non-curable pressure-sensitive adhesive layer, a conventional radiation non-curable pressure-sensitive adhesive layer may be used.

In the present invention, the storage elastic modulus of the intermediate layer is preferably 1 × 10 ⁴ to 1 × 10 ⁶ Pa, more preferably 3 × 10 ^{4 to} 5 × 10 ⁵ Pa, in order to realize the unevenness followability. . Since the rigidity is too low at 1 × 10 ⁴ Pa or less, there is a possibility that the outer layer UV curable adhesive is easily contracted by the curing shrinkage of the outer layer, or the cohesive force is insufficient and may cause adhesive residue. Yes, at 1 × 10 ⁶ Pa or more, the unevenness followability to the semiconductor wafer is insufficient. In order to improve the adhesion between the semiconductor wafer and the adhesive tape, it may be heated when the adhesive tape is bonded. In such a case, it is preferable that the storage elastic modulus is obtained at a heating temperature such as 60 ° C.

(Intermediate layer of radiation non-curable adhesive)
As the radiation non-curable adhesive (adhesive resin, base resin) used as the intermediate layer, for example, an acrylic adhesive can be used. Examples of the acrylic pressure-sensitive adhesive include (meth) acrylic acid ester monomers or (meth) acrylic acid ester copolymers composed of (meth) acrylic acid ester monomers and structural units derived from (meth) acrylic acid. Here, as the (meth) acrylic acid ester monomer, for example, (meth) acrylic acid cycloalkyl ester, (meth) acrylic acid benzyl ester, (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl group, (Meth) acrylic acid ester (for example, hydroxyethyl acrylate) which has a hydroxyl group in an alcohol part is mentioned.

As other components other than the adhesive component, those having good compatibility with the adhesive component are preferable, and as long as there is no problem in tackiness, a tackifier, a tackifier, a surfactant, or other components are used as necessary. A modifier etc. can be mix | blended. Moreover, you may add an inorganic compound filler suitably. In the present invention, the intermediate layer needs to be a radiation non-curable type, but within a range that does not affect the curing shrinkage, the peelability is improved, the cohesive force is improved, and the interlayer between the intermediate layer and the radiation curable pressure-sensitive adhesive layer For the purpose of improving adhesion or the like, a small amount of radiation curable oligomer or the like (for example, 1 to 50 parts by mass with respect to 100 parts by mass of the adhesive resin (base resin) of the intermediate layer) may be added.
Since the main purpose of making the intermediate layer non-radiation-curable is to suppress curing shrinkage, even if the intermediate layer is radiation-curable, it is cured by radiation before being bonded to a semiconductor wafer, and its elastic modulus and adhesive properties. You may adjust and use.

  The pressure-sensitive adhesive composition can contain a crosslinking agent as required. The crosslinking agent is a compound selected from polyisocyanates, melamine-formaldehyde resins, and epoxy resins, and can be used alone or in combination of two or more. The cohesive force of the pressure-sensitive adhesive can be improved after application of the pressure-sensitive adhesive by the cross-linked structure resulting from the reaction with the (meth) acrylic copolymer. Polyisocyanates are not particularly limited, and examples thereof include hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and 2,4′-dicyclohexylmethane diisocyanate. Lysine diisocyanate, lysine triisocyanate, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenyl ether diisocyanate, 4,4 ′-[2,2-bis (4-phenoxyphenyl) propane ] Diisocyanate etc. can be mentioned, Specifically, Coronate L (made by Nippon Polyurethane Co., Ltd.) etc. can be used as a commercial item. Further, as the melamine / formaldehyde resin, specifically, Nicalac MX-45 (manufactured by Sanwa Chemical Co., Ltd.), Melan (manufactured by Hitachi Chemical Co., Ltd.), etc. can be used as commercial products. Furthermore, TETRAD-X (made by Mitsubishi Chemical Corporation) etc. can be used as an epoxy resin.

  The addition amount of the crosslinking agent is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the pressure-sensitive adhesive resin (base resin), and the functional group capable of reacting with the crosslinking agent of the pressure-sensitive adhesive resin (base resin). In accordance with the number of groups (for example, hydroxyl group, carboxyl group, amino group, mercapto group), the amount thereof is appropriately adjusted in order to obtain desired adhesive properties and elastic modulus. If the addition amount is less than 0.1 parts by mass, the effect of improving the cohesive force tends to be insufficient. If the addition amount exceeds 20 parts by mass, the curing reaction proceeds rapidly during the formulation and application of the adhesive, and a crosslinked structure is formed. Since there is a tendency, workability may be impaired. The addition amount of the crosslinking agent is preferably 0.1 to 5 parts by mass in order to obtain the above storage elastic modulus.

  An intermediate | middle layer can be formed by apply | coating said adhesive composition on a base film, and drying, or apply | coating and drying on the below-mentioned peeling film, and transferring to a base film. Alternatively, the radiation curable pressure-sensitive adhesive layer provided on the intermediate layer may be laminated at one time, and may be formed by a method of applying and drying, and this method improves interlayer adhesion between the intermediate layer and the radiation curable pressure-sensitive adhesive layer. This is useful in terms of work efficiency.

(Interlayer of resin layer or resin film)
The intermediate layer may be a resin layer or a resin film. The resin layer or resin film is simply a resin layer or resin film and is not intended for adhesion, and therefore non-adhesiveness is preferred.
Such a resin layer or resin film is, for example, polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, ionomer, etc. And a homopolymer or copolymer of α-olefins or a mixture thereof. You may have two or more of these resin layers or resin films.
The resin layer or resin film used for the intermediate layer is preferably an ethylene-vinyl acetate copolymer from the viewpoint of ease of adjustment of manufacturability and elastic modulus, and the vinyl acetate content in the ethylene-vinyl acetate copolymer is 20 to When it is 50% by mass, it is suitable in terms of storage elastic modulus, heat resistance, and production handling.
The method of laminating the resin layer or the resin film is not particularly limited as long as the accuracy of the thickness of the resin layer or the resin film is within a range that does not affect the resin layer or the resin film, for example, Examples include film formation by coextrusion and bonding with an adhesive.

  On the surface of the resin layer or resin film on the side where the radiation curable pressure-sensitive adhesive layer (or radiation non-curable pressure-sensitive adhesive layer in the case of having a plurality of intermediate layers) is provided, the radiation curable pressure-sensitive adhesive layer (or a plurality of intermediate layers) In the case of having a layer, in order to improve the adhesion to the radiation non-curable pressure-sensitive adhesive layer), a treatment such as a corona treatment or a primer layer may be appropriately performed.

  The thickness of the intermediate layer is preferably 30 to 500 μm, more preferably 80 to 300 μm.

<Ray-curing adhesive layer>
The present invention has at least one ray-curable pressure-sensitive adhesive layer that is cured by irradiation with radiation and has a reduced adhesive strength on a base film, preferably an intermediate layer. Here, at least one ray-curing pressure-sensitive adhesive layer is in contact with the semiconductor wafer surface during bonding.

  The pressure-sensitive adhesive composition constituting the ray curable pressure-sensitive adhesive layer follows the irregularities when the pressure-sensitive adhesive layer is bonded to a wafer having irregularities on the surface, and has a small curing shrinkage value. Although not particularly limited, the main component polymer (adhesive base resin) is preferably a (meth) acrylic resin. By using (meth) acrylic resin as the main component polymer, it becomes easy to control the adhesive force and control the elastic modulus, etc., so that the semiconductor wafer is contaminated with organic matter, and the semiconductor wafer surface protective adhesive tape It is possible to reduce the adhesive remaining on the semiconductor wafer after the peeling.

  The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer is not particularly limited, but does not cause wafer cracking during the backgrinding process, and has adhesiveness to the extent that the pattern surface is not contaminated by dust penetration during grinding. Is preferred. Since there is a risk of wafer cracking due to radiation curing shrinkage of the adhesive as the semiconductor wafer is thinned, the shrinkage after radiation curing is small, the gas generated by the heating process is small, even after passing through the heating process It is preferable that the adhesive strength is sufficiently reduced by irradiation.

In order to cure by irradiation, the resin such as the adhesive base resin has an ethylenically unsaturated group (non-aromatic carbon-carbon double bond), or an ethylenically unsaturated group is added to the adhesive base resin. The compound which has is used together.
In the present invention, it is preferable that a resin such as an adhesive base resin having an ethylenically unsaturated group uses a resin having an ethylenically unsaturated group in the side chain. By fixing the ethylenically unsaturated group to the side chain of the adhesive base resin or the like, it becomes easy to suppress curing shrinkage due to the shrinkage of the distance between the radiation crosslinking points of the ethylenically unsaturated group.
In the case where a compound having an ethylenically unsaturated group is used in combination with the adhesive base resin, in order to suppress curing shrinkage, the number of functional groups of the ethylenically unsaturated group is, for example, 5 or less as shown in the Examples. For example, it is possible to reduce the amount to be added, not to an excessive amount, but to add moderately (for example, 50 to 100 parts by mass with respect to 100 parts by mass of the adhesive base resin).
Moreover, it is preferable to contain a photoinitiator in an adhesive composition, and it is preferable to contain a crosslinking agent in order to adjust the shrinkage | contraction after radiation hardening.

(Resin having an ethylenically unsaturated group)
Any resin having an ethylenically unsaturated group may be used, but a (meth) acrylic resin is preferred.
The iodine value that is an index of the amount of double bonds contained in the resin is preferably 0.5 to 20. The iodine value is more preferably 0.8 to 10. If the iodine value is 0.5 or more, an effect of reducing the adhesive strength after irradiation can be obtained. If the iodine value is 20 or less, excessive radiation curing can be prevented, and curing shrinkage can be suppressed. . By adjusting the amount of double bonds, it is possible in particular to adjust the adhesive strength after radiation curing.
In addition, the resin having an ethylenically unsaturated group preferably has a glass transition temperature (Tg) of −70 ° C. to 0 ° C. When the glass transition temperature (Tg) is −70 ° C. or higher, the heat resistance against heat accompanying radiation irradiation or the like increases.

  The resin having an ethylenically unsaturated group may be produced in any way, but the (meth) acrylic resin having a functional group (α) in the side chain is combined with the ethylenically unsaturated group and the functional group in the resin. A method of reacting a compound having a functional group (β) that reacts with (α) and introducing an ethylenically unsaturated group into the side chain of the (meth) acrylic resin is preferred.

The ethylenically unsaturated group may be a group such as (meth) acryloyl group, (meth) acryloyloxy group, (meth) acryloylamino group, allyl group, 1-propenyl group, vinyl group (styrene). Or a substituted styrene) is preferable, and a (meth) acryloyl group and a (meth) acryloyloxy group are more preferable.
Examples of the functional group (β) that reacts with the functional group (α) include a carboxyl group, a hydroxyl group, an amino group, a mercapto group, a cyclic acid anhydride group, an epoxy group, and an isocyanate group.

  Here, when one functional group of the functional group (α) and the functional group (β) is a carboxyl group, a hydroxyl group, an amino group, a mercapto group, or a cyclic acid anhydride group, the other functional group is , An epoxy group, and an isocyanate group. When one functional group is a cyclic acid anhydride group, the other functional group includes a carboxyl group, a hydroxyl group, an amino group, and a mercapto group. In addition, when one functional group is an epoxy group, the other functional group may be an epoxy group.

The (meth) acrylic resin having a functional group (α) in the side chain is obtained by polymerizing a (meth) acrylic acid ester, acrylic acid or (meth) acrylamide having a functional group (α).
Examples of the functional group (α) include a carboxyl group, a hydroxyl group, an amino group, a mercapto group, a cyclic acid anhydride group, an epoxy group, and an isocyanate group. A carboxyl group and a hydroxyl group are preferable, and a hydroxyl group is particularly preferable.

Such monomers include acrylic acid, methacrylic acid, cinnamic acid, itaconic acid, fumaric acid, phthalic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, glycol monoacrylates, glycol monomethacrylates, N-methylolacrylamide, N-methylolmethacrylamide, allyl alcohol, N-alkylaminoethyl acrylates, N-alkylaminoethyl methacrylates, acrylamides, methacrylamides, maleic anhydride, itaconic anhydride, fumaric anhydride, anhydrous Phthalic acid, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, some isocyanate groups of polyisocyanate compounds are hydroxyl or carboxyl groups and radiation curable Containing - like a like those urethanization a monomer having a carbon-carbon double bond.
Among these, acrylic acid, methacrylic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, glycidyl acrylate, glycidyl methacrylate are preferable, and acrylic acid, methacrylic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylate Are more preferable, and 2-hydroxyalkyl acrylates and 2-hydroxyalkyl methacrylates are more preferable.

The resin having a tylene unsaturated group, particularly a resin having an ethylenically unsaturated group, is preferably a copolymer with other monomers such as a (meth) acrylic acid ester together with the above-mentioned monomers.
As (meth) acrylic acid ester, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl Acrylate, dodecyl acrylate, decyl acrylate hexyl acrylate, and the corresponding methacrylates.
Although the (meth) acrylic acid ester may be one type or two or more types, it is preferable to use those having an alcohol part having 5 or less carbon atoms and those having 6 to 12 carbon atoms.
The resin having an ethylenically unsaturated group is preferably a resin obtained by further copolymerizing (meth) acrylic acid in addition to (meth) acrylic acid ester.

  The (meth) acrylic resin includes, for example, a monomer mixture mainly composed of (meth) acrylic acid alkyl ester as described in JP-A-2003-82307, and an average addition of ethylene or propylene oxide containing a radical polymerizable functional group. An acrylic emulsion polymer obtained by emulsion polymerization using a nonionic anionic emulsifier having a mole number of 15 or less and a redox polymerization initiator can be a main component.

  In addition, it is mainly composed of an acrylic emulsion polymer and is obtained by emulsion polymerization of (meth) acrylic acid alkyl ester as the main monomer and, if necessary, other monomers copolymerizable with these main monomers. Can be used.

The polymerization reaction of a resin having an ethylenically unsaturated group, particularly a resin having an ethylenically unsaturated group, may be any of solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization.
When the (meth) acrylic resin having a functional group (α) in the side chain is reacted with a compound having an ethylenically unsaturated group and a functional group (β) that reacts with the functional group (α) in the resin, By making it react excessively and leaving an unreacted functional group, it is possible to adjust to desired adhesive properties and elastic modulus.

  As the organic solvent in the case of solution polymerization, ketone, ester, alcohol and aromatic solvents can be used, among which toluene, ethyl acetate, isopropyl alcohol, benzene methyl cellosolve, ethyl cellosolve, acetone In general, a good solvent for an acrylic polymer such as methyl ethyl ketone, preferably a solvent having a boiling point of 60 to 120 ° C. If emulsion polymerization is used, water or a water-soluble solvent mixed with water is used, and a surfactant is used. Is preferred.

  As the polymerization initiator, a radical generator such as an azobis type such as α, α'-azobisisobutylnitrile or an organic peroxide type such as benzoyl peroxide is usually used. At this time, if necessary, a catalyst and a polymerization inhibitor can be used in combination, and a resin having a desired molecular weight can be obtained by adjusting the polymerization temperature and the polymerization time. In terms of adjusting the molecular weight, it is preferable to use a mercaptan or carbon tetrachloride solvent.

  The mass average molecular weight of the resin having an ethylenically unsaturated group is preferably about 200,000 to 1,500,000, more preferably 700,000 to 1,200,000. By using a polymer, the cohesive force can be maintained without excessively increasing the crosslinking density due to radiation curing, which is advantageous in suppressing curing shrinkage. Further, by reducing the low molecular weight component, it is possible to suppress the surface contamination of the semiconductor wafer. For example, it is preferable that the number of molecules having a molecular weight of 100,000 or less is 10% or less. If the molecular weight exceeds 1,500,000, there is a possibility of gelation during synthesis and coating. If the resin having an ethylenically unsaturated group has an OH group having a hydroxyl value of 5 to 100 mgKOH / g, the risk of tape peeling failure can be further reduced by reducing the adhesive strength after radiation irradiation. It is preferable because it is possible.

A compound having a functional group (β) that reacts with an ethylenically unsaturated group and a functional group (α) will be described.
The ethylenically unsaturated group is preferably the group described above, and the preferred range is also the same.
Examples of the functional group (β) that reacts with the functional group (α) include the groups described above. As the functional group (β), an isocyanate group is preferable.

  Examples of the compound having a functional group (β) that reacts with the ethylenically unsaturated group and the functional group (α) include a monomer compound having a functional group (α), and a (meth) acrylate having an isocyanate group in the alcohol part. A (meth) acrylate having an isocyanate group in the alcohol part is preferred. As the (meth) acrylate having an isocyanate group in the alcohol part, those having an isocyanate group at the terminal of the alcohol part are preferable, and the number of carbons other than the isocyanate group in the alcohol part is preferably 2 to 8, and the alcohol part is a linear alkyl. Those are preferred. Preferred examples of the (meth) acrylate having an isocyanate group in the alcohol part include 2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate.

(Crosslinking agent)
As the crosslinking agent, polyisocyanates, melamine / formaldehyde resins or epoxy compounds having two or more epoxy groups are preferable, and polyisocyanates are particularly preferable.
A crosslinking agent can be used individually or in combination of 2 or more types. By crosslinking the resin polymer, the crosslinking agent can improve the cohesive strength of the adhesive after application of the adhesive. Moreover, the adhesive force before radiation crosslinking can be adjusted by adjusting the addition amount.

  Examples of polyisocyanates include hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 2,4′-dicyclohexylmethane diisocyanate, lysine diisocyanate, and lysine. Examples include triisocyanate, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenyl ether diisocyanate, 4,4 ′-[2,2-bis (4-phenoxyphenyl) propane] diisocyanate, and the like. Specifically, Coronate L (made by Nippon Polyurethane Co., Ltd.) etc. can be used as a commercial item.

  As the melamine / formaldehyde resin, Nicalac MX-45 (manufactured by Sanwa Chemical Co., Ltd.), Melan (manufactured by Hitachi Chemical Co., Ltd.) and the like can be used as commercial products. Furthermore, TETRAD-X (made by Mitsubishi Chemical Corporation) etc. can be used as an epoxy resin.

  The addition amount of the crosslinking agent is preferably 0.1 to 20 parts by mass, more preferably 1.0 to 10 parts by mass with respect to 100 parts by mass of the resin having an ethylenically unsaturated group, In accordance with the number of functional groups of the resin having an unsaturated group, the amount is appropriately adjusted in order to obtain desired adhesive properties and elastic modulus. When the amount of the crosslinking agent is less than 0.1 parts by mass, the cohesive force improving effect tends to be insufficient. When the amount exceeds 20 parts by mass, the curing reaction proceeds rapidly during the blending and application of the adhesive, and a crosslinked structure is formed. Therefore, workability may be impaired. By crosslinking with a crosslinking agent, rapid crosslinking due to radiation curing can be prevented and curing shrinkage can be suppressed.

(Photopolymerization initiator)
The radiation curable pressure-sensitive adhesive layer can contain a photopolymerization initiator as necessary. As long as it reacts with the radiation which permeate | transmits a base material as a photoinitiator, there will be no restriction | limiting in particular, A conventionally well-known thing can be used. For example, benzophenones such as benzophenone, 4,4′-dimethylaminobenzophenone, 4,4′-diethylaminobenzophenone and 4,4′-dichlorobenzophenone, acetophenones such as acetophenone and diethoxyacetophenone, 2-ethylanthraquinone, t- Anthraquinones such as butylanthraquinone, 2-chlorothioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzyl, 2,4,5-triallylimidazole dimer (rophine dimer), acridine compound, acylphosphine oxide These may be used alone or in combination of two or more.
The addition amount of the photopolymerization initiator is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the resin having an ethylenically unsaturated group. More preferably, it is 0.5 to 3 parts by mass. When the amount of photopolymerization initiator added is large, radiation curing occurs at multiple points and suddenly occurs, resulting in increased curing shrinkage. Therefore, photopolymerization starts compared to conventional radiation-curing surface protection adhesive tapes. Reducing the amount of the agent is also useful from the viewpoint of suppressing curing shrinkage.

(Other additives)
If necessary, the radiation curable pressure-sensitive adhesive layer may contain a tackifier, a tackifier, a surfactant, or other modifiers. Moreover, you may add an inorganic compound filler suitably.

The radiation curable pressure-sensitive adhesive layer is formed by applying the radiation curable pressure-sensitive adhesive composition on a substrate film (on the intermediate layer when an intermediate layer is provided) and drying, or applying on a release film described later, It can be formed by drying and transferring to a base film (on the intermediate layer when an intermediate layer is provided).
Peeling from the semiconductor wafer is lightened by the presence of the radiation curable pressure-sensitive adhesive layer, but it is necessary to have a certain thickness or more to exert its effect. Absent. Specifically, Ri thickness 1~30μm der, it is more preferable and 5 to 20 [mu] m. The radiation curable pressure-sensitive adhesive layer may have a structure in which a plurality of radiation curable pressure-sensitive adhesive layers are laminated.
In the present invention, the total thickness of the layers on the base film on the side having the radiation curable pressure-sensitive adhesive layer of the adhesive tape for protecting the semiconductor wafer surface is the unevenness present on the surface of the semiconductor wafer to be protected. It is preferably at least the maximum difference between the height at the top and the height at the bottom, and more preferably at least 120% of the maximum difference.

That is, when it has an intermediate layer, the total thickness of the intermediate layer and the radiation curable pressure-sensitive adhesive layer is not less than the maximum difference between the height of the top and bottom of the unevenness present on the semiconductor wafer surface to be processed. Is preferable, and more preferably 120% or more of the maximum difference.
In addition, the adhesive tape for semiconductor wafer surface protection of this invention is a semiconductor wafer whose maximum difference of the height of the top part of the unevenness | corrugation which exists in the surface by the side of the bonding surface of the semiconductor wafer to bond is 10-300 micrometers. More preferably, it is used for a semiconductor wafer having a thickness of 80 to 200 μm.

(Peeling film)
The release film is also called a separator, a release layer, or a release liner, and is provided as necessary for the purpose of protecting the radiation curable pressure-sensitive adhesive layer and for the purpose of smoothing the radiation curable pressure-sensitive adhesive. Examples of the constituent material of the release film include synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate, and paper. The surface of the release film may be subjected to release treatment such as silicone treatment, long-chain alkyl treatment, fluorine treatment, etc. as necessary in order to enhance the peelability from the radiation curable pressure-sensitive adhesive layer. Further, if necessary, an ultraviolet ray prevention treatment may be performed so that the pressure-sensitive adhesive layer does not react with environmental ultraviolet rays. The thickness of the release film is usually about 10 to 100 μm, preferably about 25 to 50 μm.

<< Semiconductor Wafer Manufacturing Method >>
The method for manufacturing a semiconductor wafer according to the present invention includes the steps of protecting the wafer surface of the semiconductor wafer with the adhesive tape for protecting the surface of the semiconductor wafer, grinding the back surface of the wafer, and processing the semiconductor wafer.
The semiconductor wafer of the present invention is a semiconductor in which the maximum difference between the height of the top and bottom of the unevenness present on the surface on the bonding surface side of the semiconductor wafer to which the adhesive tape for protecting the surface of the semiconductor wafer is bonded is 10 to 300 μm. It is preferably used for a wafer.
The total thickness of the layers on the base film on the side having the radiation curable pressure-sensitive adhesive layer of the semiconductor wafer surface protecting adhesive tape used for protecting the wafer surface of the semiconductor wafer is the surface roughness of the semiconductor wafer to be protected. It is preferable to use adhesive tape for semiconductor wafer surface protection according to the height, for surface protection more than the maximum difference between the height of the top and bottom of the unevenness present on the surface of the bonding surface of the semiconductor wafer Use adhesive tape.

Thus, the surface unevenness of the semiconductor wafer to be protected is investigated in advance, and the total thickness of the layers on the base film on the side having the radiation curable pressure-sensitive adhesive layer of the adhesive tape for surface protection is adjusted, or A plurality of different thickness adhesive tapes for surface protection can be prepared and used by selecting from them.
A normal semiconductor wafer manufacturing process can be applied except that the semiconductor wafer surface protecting adhesive tape is used in consideration of the relationship between the semiconductor wafer surface protecting adhesive tape and the surface irregularities of the semiconductor wafer to be protected.

  Specifically, first, the adhesive tape for protecting a semiconductor wafer surface of the present invention is bonded to the circuit pattern surface (front surface) of the semiconductor wafer so that the radiation curable pressure-sensitive adhesive layer becomes the bonding surface. Next, the surface side of the semiconductor wafer having no circuit pattern is ground until the thickness of the semiconductor wafer reaches a predetermined thickness, for example, 10 to 200 μm. After that, the surface of the adhesive tape for protecting the surface of the semiconductor wafer is placed on the heating adsorption table, and in that state, a dicing die bonding film is applied to the ground surface without the circuit pattern of the semiconductor wafer. You may paste. Thereafter, a heat seal type (thermal fusion type) or adhesive type release tape is adhered to the back surface of the base film of the semiconductor wafer surface protective adhesive tape to peel the semiconductor wafer surface protective adhesive tape from the semiconductor wafer.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

  A pressure-sensitive adhesive composition was prepared as described below, a pressure-sensitive adhesive tape for protecting a semiconductor wafer surface was prepared by the following method, and its performance was evaluated.

(Preparation of pressure-sensitive adhesive composition)
[Adhesive composition 2A]
To 100 parts by mass of a copolymer consisting of 80 parts by mass of 2-ethylhexyl acrylate, 19 parts by mass of 2-hydroxyacrylate, and 1 part by mass of methacrylic acid, 0.5 part by mass of Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) is added as polyisocyanate. And mixed to obtain an adhesive composition 2A. The storage elastic modulus was measured and found to be 4 × 10 ⁴ Pa.

[Adhesive composition 2B]
To 100 parts by mass of a copolymer consisting of 85 parts by mass of 2-ethylhexyl acrylate, 14 parts by mass of 2-hydroxy acrylate, and 1 part by mass of methacrylic acid, 10 parts by mass of methacryloyloxyethyl isocyanate as a radiation reactive group is reacted. As a photopolymerization initiator, 0.3 parts by mass of Coronate L and 5.0 parts by mass of SPEEDCURE BKL were added and mixed to obtain an adhesive composition 2A. The storage elastic modulus was measured and found to be 3 × 10 ⁴ Pa.

[Adhesive composition 2C]
A pressure-sensitive adhesive composition 2C was obtained in the same manner as 2A except that the amount of Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) was changed to 0.3 parts by mass. The storage elastic modulus was measured and found to be 3 × 10 ⁴ Pa.

[Adhesive composition 2D]
A pressure-sensitive adhesive composition 2D was obtained in the same manner as 2B except that 1.0 part by mass of Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) and SPEEDCURE BKL2.0 were changed to part by mass. The storage elastic modulus was measured and found to be 6 × 10 ⁴ Pa.

[Adhesive composition 2E]
With respect to 100 parts by mass of a copolymer consisting of 69 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of 2-hydroxyacrylate, 10 parts by mass of methyl methacrylate, and 1 part by mass of methacrylic acid, 10 parts by mass of methacryloyloxyethyl isocyanate as a radiation reactive group. Parts were reacted, 1.0 part by mass of Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) as a polyisocyanate, and 3.0 parts by mass of SPEDCURE BKL as a photopolymerization initiator were added and mixed to obtain an adhesive composition 2E. The storage elastic modulus was measured and found to be 4 × 10 ⁴ Pa.

[Adhesive composition 2F]
To 100 parts by mass of a copolymer consisting of 80 parts by mass of 2-ethylhexyl acrylate, 19 parts by mass of 2-hydroxyacrylate, and 1 part by mass of methacrylic acid, 70 parts by mass of a pentafunctional urethane acrylate oligomer, and Coronate L (Japan) Polyurethane Co., Ltd.) 3.0 parts by mass and SPEDCURE BKL 3.0 parts by mass as a photopolymerization initiator were added and mixed to obtain an adhesive composition 2F. The storage elastic modulus was measured and found to be 5 × 10 ⁴ Pa.

[Adhesive composition 2G]
100 parts by mass of a pentafunctional urethane acrylate oligomer and 100 parts by mass of a copolymer consisting of 85 parts by mass of 2-ethylhexyl acrylate, 14 parts by mass of 2-hydroxyacrylate and 1 part by mass of methacrylic acid, and Coronate L (Japan) Polyurethane Co., Ltd.) 2.0 parts by mass and SPEDCURE BKL 3.0 parts by mass as a photopolymerization initiator were added and mixed to obtain an adhesive composition 2G. The storage elastic modulus was measured and found to be 4 × 10 ⁴ Pa.

[Adhesive composition 2H]
60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of 2-hydroxyacrylate, 17 parts by mass of butyl acrylate, 100 parts by mass of methacrylic acid, 100 parts by mass of hexafunctional urethane acrylate oligomer, poly As an isocyanate, 3.0 parts by mass of Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) and 5.0 parts by mass of SPEEDCURE BKL as a photopolymerization initiator were added and mixed to obtain an adhesive composition 2H. The storage elastic modulus was measured and found to be 4 × 10 ⁴ Pa.

[Adhesive composition 2I]
60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of 2-hydroxy acrylate, 15 parts by mass of butyl acrylate, 100 parts by mass of methacrylic acid, 70 parts by mass of hexafunctional urethane acrylate oligomer, poly 2.0 parts by mass of Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) as isocyanate and 5.0 parts by mass of SPEEDCURE BKL as a photopolymerization initiator were added and mixed to obtain an adhesive composition 2I. The storage elastic modulus was measured and found to be 4 × 10 ⁴ Pa.

[Adhesive composition 2J]
Except having changed the compounding quantity of Coronate L (made by Nippon Polyurethane Co., Ltd.) into 2.0 mass parts, adhesive composition 2J was obtained by the method similar to 2B. The storage elastic modulus was measured and found to be 8 × 10 ⁴ Pa.

Here, the storage elastic modulus was measured as follows.
[Storage modulus]
The storage elastic modulus was measured at a frequency of 0.6 rad / sec using a dynamic viscoelasticity measuring device (for example, ARES manufactured by TA Instruments). About temperature, it heated up to 0-100 degreeC and the value of the storage elastic modulus of 25 degreeC and 60 degreeC was confirmed. In addition, about the Example, the value of 60 degreeC is shown.
When the sample was a pressure-sensitive adhesive composition, a pressure-sensitive adhesive that had been applied and dried on a release-treated separator was stacked and punched into a pellet shape having a thickness of about 2 mm. When the sample is a resin layer, a resin layer is formed on a PET film that has been subjected to a release treatment, and the PET film is peeled off from a piece cut out to 50 mm × 50 mm, and stacked until it has a thickness of about 2 mm. After heating at 150 ° C. for 3 hours, the sample was punched into pellets.

[Preparation of radiation-curable semiconductor wafer surface protection adhesive tape]
<Example 1>
On the 38 μm thick polyethylene terephthalate (PET) separator, the adhesive composition 2A was applied as an intermediate layer so that the film thickness after drying was 95 μm, and after drying, the 200 μm thick ethylene-vinyl acetate copolymer was coated. The film was bonded to a base film made of a polymer (EVA) film. Furthermore, on the 38 μm thick polyethylene terephthalate (PET) separator, the pressure-sensitive adhesive composition 2D was applied so that the film thickness after drying was 5 μm, dried, and then bonded to the intermediate layer surface from which the separator was peeled off, An adhesive tape for protecting the surface of a semiconductor wafer having a thickness of 300 μm was obtained.

<Example 2>
On a 38 μm thick polyethylene terephthalate (PET) separator, the pressure-sensitive adhesive composition 2A was applied as an intermediate layer so that the film thickness after drying was 90 μm, and after drying, a 200 μm thick ethylene-vinyl acetate copolymer was coated. The film was bonded to a base film made of a polymer (EVA) film. Further, the pressure-sensitive adhesive composition 2E was applied on a 38 μm thick polyethylene terephthalate (PET) separator so that the film thickness after drying was 30 μm, dried, and then bonded to the intermediate layer surface from which the separator was peeled off. An adhesive tape for protecting the surface of a semiconductor wafer having a thickness of 320 μm was obtained.

<Example 3>
A laminated substrate film (total thickness 200 μm) of polypropylene resin (PP) 50 μm and an ethylene-vinyl acetate copolymer (EVA) 150 μm of a storage elastic modulus 9 × 10 ⁴ Pa at 60 ° C. was prepared by coextrusion film formation. The pressure-sensitive adhesive composition 2F was applied on a 38 μm thick polyethylene terephthalate (PET) separator so that the film thickness after drying was 20 μm, dried, and then bonded to the EVA film surface of the laminated base film. A pressure-sensitive adhesive tape for protecting the surface of a semiconductor wafer having a thickness of 220 μm was obtained.

<Example 4>
A laminated substrate film (total thickness 250 μm) of low-density polyethylene (LDPE) 50 μm and ethylene-vinyl acetate copolymer (EVA) 200 μm with a storage elastic modulus 1 × 10 ⁵ Pa at 60 ° C. was prepared by coextrusion film formation. . The pressure-sensitive adhesive composition 2D was applied on a 38 μm thick polyethylene terephthalate (PET) separator so that the film thickness after drying was 10 μm, dried, and then bonded to the EVA film surface of the laminated base film. A pressure-sensitive adhesive tape for protecting the surface of a semiconductor wafer having a thickness of 260 μm was obtained.

<Example 5>
From the low-density polyethylene (LDPE) film having a thickness of 100 μm, the pressure-sensitive adhesive composition 2G was applied on a 38 μm-thick polyethylene terephthalate (PET) separator so that the film thickness after drying was 30 μm and dried. The resulting substrate film was laminated to obtain a semiconductor wafer surface protecting adhesive tape having a thickness of 130 μm.

<Comparative Example 1>
A semiconductor wafer protecting adhesive tape was obtained in the same manner as in Example 1 except that 2B was used instead of the adhesive composition 2A as an intermediate layer.

<Comparative example 2>
The pressure-sensitive adhesive composition 2H was applied onto a polyethylene terephthalate (PET) separator having a thickness of 38 μm so that the film thickness after drying was 60 μm, dried, and then an ethylene-vinyl acetate copolymer having a thickness of 200 μm ( It was bonded to a base film made of EVA) film. Further, the pressure-sensitive adhesive composition 2H was applied on a polyethylene terephthalate (PET) separator having a thickness of 38 μm so that the film thickness after drying was 60 μm, and after drying, the separator was peeled off. An adhesive tape for protecting the surface of a semiconductor wafer having a thickness of 320 μm and a dried 2H surface was obtained.

<Comparative Example 3>
The adhesive composition 2C was applied as an intermediate layer on a 38 μm thick polyethylene terephthalate (PET) separator so that the film thickness after drying was 90 μm, dried, and then 100 μm thick polyethylene terephthalate (PET). The film was bonded to a base film made of a film. Further, the pressure-sensitive adhesive composition 2I was applied onto a 38 μm thick polyethylene terephthalate (PET) separator so that the film thickness after drying was 30 μm, dried, and then bonded to the intermediate layer surface from which the separator was peeled off. An adhesive tape for protecting the surface of a semiconductor wafer having a thickness of 220 μm was obtained.

<Comparative example 4>
The pressure-sensitive adhesive composition 2J was applied on a polyethylene terephthalate (PET) separator having a thickness of 38 μm so that the film thickness after drying was 30 μm, dried, and then an ethylene-vinyl acetate copolymer having a thickness of 100 μm ( An adhesive tape for protecting the surface of a semiconductor wafer having a thickness of 130 μm was obtained by laminating with a base film made of an EVA) film.

  The adhesive force and tack force of each of the semiconductor wafer processing adhesive tapes thus produced were measured.

[Adhesive force]
A test piece having a width of 25 mm and a length of 300 mm was cut out from the adhesive tape for semiconductor wafer processing. The test piece is reciprocated three times on a 2 kg rubber roller on a 1.5 mm-thick stainless steel (Steel Use Stainless, SUS) plate specified in JIS G 4305 finished with 280 No. 280 water-resistant abrasive paper specified in JIS R 6253. After crimping and allowing to stand for 1 hour, before irradiation with an Instron tensile tester (Twin Column Tabletop Model 5567) conforming to JIS B 7721 whose measured value falls within the range of 15 to 85% of its capacity. The adhesive strength A was measured. Similarly, after 1 hour has passed after the pressure-sensitive adhesive tape has been pressure-bonded, 1000 mJ / cm ² (illuminance: 40 mW / cm ² ) is irradiated from the back surface of the base film of the pressure-sensitive adhesive tape, left for 1 hour, and then irradiated with radiation. The adhesive strength B of was measured. The measurement is performed by a 180 ° peeling method under the conditions of a pulling speed of 300 mm / min, 25 ° C., and a relative humidity of 50%. The measurement is performed three times for each adhesive tape, and an average value thereof is obtained. did.

[Tacking power]
A test piece having a width of 25 mm and a length of 150 mm was cut out from the adhesive tape for processing a semiconductor wafer. Using a tacking tester (trade name: TACII, manufactured by Resca), a 3 mmφ cylindrical probe was pushed at a speed of 30 mm / min into the pressure-sensitive adhesive layer to be bonded to the surface of the semiconductor wafer, and held at a stop load of 100 gf for 1 second. The peak load when pulling up later at a speed of 600 mm / min was defined as tack force C before radiation irradiation. After the test piece was cut out, 1000 mJ / cm ² of ultraviolet light (illuminance: 40 mW / cm ² ) was irradiated from the back of the base film, and the test piece was left for 1 hour to obtain a tack force D after irradiation by the same method. It was. The measurement was performed under the conditions of 25 ° C. and 50% relative humidity, and five different points were measured in each test piece of each adhesive tape, and the arithmetic average value thereof was obtained, which was used as the tack force.

[Performance evaluation]
The following evaluation was performed on each of the adhesive wafers for processing semiconductor wafers of Examples 1 to 5 and Comparative Examples 1 to 4.

(Wafer backside state after wafer grinding)
A pressure-sensitive adhesive tape for semiconductor wafer processing was bonded to an 8-inch semiconductor wafer having bumps of 100 μm in height on the surface at a bonding temperature of 60 ° C. Then, using DFG8760 (trade name) manufactured by DISCO Corporation, two bumped semiconductor wafers were ground to a thickness of 75 μm, and the back surface of the semiconductor wafer was visually observed. The evaluation of the semiconductor wafer back surface state is as follows: a semiconductor wafer with no damage or dimples occurring on two semiconductor wafers as a non-defective product, a product with no damage and a partial dimple generated as a good product, In all of the two semiconductor wafers, those in which breakage or dimples occurred on the entire surface of the semiconductor wafers are indicated by x as defective products. In addition, cutting water intrusion from the outer periphery of the wafer after grinding was investigated. The case where no intrusion was observed was indicated by ○, and the case where infiltration was observed was indicated by ×.

(Adhesive residue evaluation)
The ground semiconductor wafer was irradiated with 1000 mJ / cm ² of ultraviolet light and peeled off at a peeling temperature of 25 ° C. using RAD2700 (trade name) manufactured by Lintec Corporation. After peeling, the semiconductor wafer was visually observed for damage and adhesive residue. A product in which no damage or adhesive residue occurred on all two semiconductor wafers was indicated as a non-defective product. A single product in which one or more damages or adhesive residue was generated was indicated as x. .

As shown in Table 1, the curing shrinkage value S is 0.3 to 1.8 , the adhesive strength A before irradiation is 1.5 to 20 N / 25 mm, and the adhesive strength B after irradiation is 0. In Examples 1 to 5 satisfying .01 to 1.5 N / 25 mm, it adheres well to the semiconductor wafer at the time of grinding, prevents infiltration of grinding water, and is applied to the surface of the semiconductor wafer after peeling the adhesive tape for processing the semiconductor wafer. No adhesive residue or damage to the semiconductor wafer occurred. On the other hand, as shown in Table 1, in Comparative Examples 1, 2, and 3 having a large curing shrinkage value S, the adhesive residue was mainly confirmed at the joint portion of the bump because the curing shrinkage S was large. Further, in Comparative Example 4 in which the adhesive strength A before irradiation was low, no adhesive residue was generated, but contamination on the surface of the semiconductor wafer due to infiltration of grinding water was confirmed due to insufficient adhesion.

  As described above, the adhesive tape for protecting the surface of a semiconductor wafer of the present invention has a small curing shrinkage due to radiation curing even when the semiconductor wafer has an uneven surface, and the semiconductor wafer is not damaged or the adhesive remains after peeling.

Claims (6)

It is an adhesive tape for surface protection used when it is bonded to a semiconductor wafer and subjected to back grinding,
It has at least one radiation-curable pressure-sensitive adhesive layer on the base film, has the following curing shrinkage value S of 0.3 to 1.8 , and has an adhesive force A before irradiation of radiation on the polished surface of stainless steel. a 1.5~20N / 25mm, and Ri adhesive force B is 0.01~1.5N / 25mm der after irradiation,
The maximum difference between the height of the top and bottom of the unevenness present on the surface of the semiconductor wafer surface protecting adhesive tape of the semiconductor wafer is 10 to 300 μm, and the radiation curable pressure-sensitive adhesive layer semiconductor wafer surface protecting adhesive tape having a thickness and wherein 1~30μm der Rukoto.
Curing shrinkage value S = {(B / A) / (D / C)}
(In the above, A represents the adhesive force before irradiation with respect to the polished surface of stainless steel, B represents the adhesive force after irradiation with respect to the polished surface of stainless steel, and C represents the tack force before irradiation on the surface of the adhesive tape. And D represents the tack force after radiation irradiation on the adhesive tape surface.) A radiation non-curing pressure-sensitive adhesive layer having a storage elastic modulus at 25 ° C. or 60 ° C. in a laminator of 1 × 10 ⁴ to 1 × 10 ⁶ Pa between the base film and the radiation-irradiating pressure-sensitive adhesive layer or The adhesive tape for protecting a semiconductor wafer surface according to claim 1, further comprising an intermediate layer made of a resin. The total thickness of the layers present on the side of the base film having the radiation-curable pressure-sensitive adhesive layer, wherein is the maximum difference over the height of the height and the bottom of the top of the irregularities present on the semiconductor wafer surface The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to claim 1 or 2. A method for manufacturing a semiconductor wafer, comprising: protecting a wafer surface of a semiconductor wafer with an adhesive tape for surface protection having an adhesive layer on a base film; and grinding the back surface of the wafer to process the semiconductor wafer. ,
The pressure-sensitive adhesive tape for surface protection has at least one radiation-curing pressure-sensitive adhesive layer on the base film, has the following curing shrinkage value S of 0.3 to 1.8 , and radiation on the polished surface of stainless steel a pressure-sensitive adhesive force a is 1.5~20N / 25mm prior to irradiation, and Ri adhesive force B is 0.01~1.5N / 25mm der after irradiation,
The maximum difference between the height of the top and bottom of the unevenness present on the surface of the semiconductor wafer surface protecting adhesive tape of the semiconductor wafer is 10 to 300 μm, and the radiation curable pressure-sensitive adhesive layer the method of manufacturing a semiconductor wafer having a thickness and wherein 1~30μm der Rukoto.
Curing shrinkage value S = {(B / A) / (D / C)}
(In the above, A represents the adhesive force before irradiation with respect to the polished surface of stainless steel, B represents the adhesive force after irradiation with respect to the polished surface of stainless steel, and C represents the tack force before irradiation on the surface of the adhesive tape. And D represents the tack force after radiation irradiation on the adhesive tape surface.) The surface protective adhesive tape has a storage elastic modulus at 25 ° C. or 60 ° C. of 1 × 10 ⁴ to 1 × 10 ⁶ Pa in a laminator between the base film and the radiation-irradiating adhesive layer. The method for producing a semiconductor wafer according to claim 4, further comprising an intermediate layer composed of a radiation non-curable adhesive layer or a resin. The total thickness of the layers present on the side of the base film having the radiation-curable pressure-sensitive adhesive layer, wherein is the maximum difference over the height of the height and the bottom of the top of the irregularities present on the semiconductor wafer surface 6. The method for producing a semiconductor wafer according to claim 4, wherein the method is a semiconductor wafer.