TW201510163A - Composite sheet for forming protective film, chip having protective film, and production method for chip having protective film - Google Patents

Abstract

A composite sheet for forming a protective film, having: an adhesive sheet having a base material and an adhesive layer and including a cured area inside the adhesive layer; and a film for forming a protective film, which is directly laminated upon the cured area inside the adhesive layer. The adhesive layer comprises an adhesive composition including an energy ray-curable acrylic copolymer having an energy ray-polymerizable group introduced to an acrylic polymer (X) including a vinyl acetate-derived constituent unit (x1). The composite sheet for forming a protective film is capable of producing a chip having a protective film and having: a high suppression effect on the incursion of cutting fluid between the film for forming a protective film (protective film) and the adhesive layer when dicing a workpiece such as a wafer, etc.; excellent aptitude for pick up during chip production; and excellent visibility of a laser printing section on the protective film surface.

Description

Composite sheet for forming protective film, wafer with protective film, and method for manufacturing wafer with protective film

The present invention relates to a composite sheet for forming a protective film which can form a protective film on the back surface of a workpiece such as a semiconductor wafer or a semiconductor wafer and can improve the production efficiency of the semiconductor wafer, and has a protective film for forming the composite sheet on the back surface of the semiconductor wafer. A wafer with a protective film for a protective film obtained by hardening a film, and a method for producing a wafer with a protective film.

In recent years, the manufacture of a semiconductor device using an assembly method called a face down method has been carried out. In the face-down method, a semiconductor wafer (hereinafter also referred to simply as "wafer") having electrodes such as bumps on a circuit surface is used, and the electrodes and the substrate are bonded. Therefore, the surface of the wafer opposite to the circuit surface (hereinafter also referred to as "the back surface of the wafer") is exposed.

The back surface of the exposed wafer is protected by a protective film made of an organic material, and is mounted as a protective film on the semiconductor device. In general, the wafer with the protective film can be coated with a liquid resin on the back surface of the wafer by spin coating or the like, dried, and cured to form a protective film on the back surface of the wafer, and the resulting film is attached. The wafer of the protective film is cut.

However, the above-described method for manufacturing a wafer with a protective film is a large number of steps, resulting in an increase in the cost of the product.

Moreover, the protective film formed of the liquid resin as described above has a problem that the yield of the obtained protective film-containing wafer is lowered due to insufficient thickness accuracy.

As a means for solving the above problems, Patent Document 1 discloses a film for protecting a wafer having a release sheet and a protective film forming layer composed of an energy ray-curable component and a binder polymer component formed on the release sheet. .

Nowadays, semiconductor wafers have been thinned and densified. Even when exposed to severe temperature conditions, semiconductor devices incorporating wafers with protective films are required to have higher reliability.

According to the review by the present inventors, the protective film for a wafer described in Patent Document 1 has a problem that shrinkage or warpage of the semiconductor wafer occurs when the protective film forming layer is cured. In particular, when an extremely thin semiconductor wafer is used, the above problems tend to occur remarkably. If the semiconductor wafer is warped, the wafer may be damaged or the printing accuracy of the protective film may be lowered.

In order to solve the above problem, the present applicant has proposed a film for forming and cutting a protective film as Patent Document 2, which comprises a slightly circular region formed of a protective film forming layer thereon, and a re-peeling adhesion surrounding the aforementioned region. The annular region formed by the agent.

When the semiconductor wafer is placed on the protective film forming layer of the protective film forming and cutting sheet, and the laser marking is performed in the state of the peripheral portion of the ring frame fixing sheet, the warpage of the wafer can be corrected. The state of the printing, and the accuracy of the printing is increased.

Moreover, since the sheet also serves as a dicing sheet, it is not necessary to separately prepare a dicing sheet, and productivity is remarkably improved.

Patent Document 2 discloses a purpose of fixing a wafer on a protective film forming and dicing sheet, and heat-hardening the protective film forming layer while the wafer is fixed, thereby forming a protective film on the wafer.

Prior technical literature Patent literature

Patent Document 1 JP-A-2009-138026

Patent Document 2, JP-A-2006-140348

However, the protective film forming and cutting sheet having the configuration described in Patent Document 2 is formed by heat-hardening the protective film forming layer, and when the protective film is subjected to laser printing, the printed portion is poor in visibility. There is room for improvement. It is also required that the wafer attachability and the pick-up adaptability after the heat hardening further coexist.

Further, in the dicing sheet in which the film for forming a protective film is laminated on the adhesive layer of a general adhesive sheet, the film for protective film formation or the protective film is also used for dicing the wafer to which the sheet is attached. Between the adhesive layers, the cutting water is infiltrated, which contaminates the manufactured wafer with the protective film.

An object of the present invention is to provide a composite sheet for forming a protective film which is capable of suppressing penetration of cutting water into a film for forming a protective film or a film between a protective film and an adhesive layer when cutting a workpiece such as a wafer. It is high in pick-up property at the time of wafer manufacturing, and it is possible to manufacture a wafer with a protective film which is excellent in visibility of a laser printed portion on a surface of a protective film.

In addition, it is an object of the present invention to provide a wafer with a protective film and a protective film-attached wafer having a protective film formed by curing the protective film for forming a protective film.

The present inventors have found that a composite sheet for forming a protective film having an adhesive layer can solve the above problems and complete the present invention. The pressure-sensitive adhesive layer is formed of an adhesive composition containing an energy ray-curable acrylic polymer having a specific constituent unit and an energy ray-polymerizable group, and a hardened region is provided at a position where the film for forming a protective film is laminated.

That is, the present invention provides the following [1] to [13].

[1] A composite sheet for forming a protective film, comprising a composite sheet for forming a protective film for forming an adhesive sheet and a film for forming a protective film, the adhesive sheet having a substrate and an adhesive layer and containing a hardened region in the adhesive layer. The film for forming a protective film is directly laminated on a hardened region in the adhesive layer; the adhesive layer is a layer formed of an adhesive composition containing an energy ray-curable acrylic copolymer, and the energy ray-curable type The acrylic copolymer is obtained by introducing an energy ray polymerizable group to an acrylic polymer (X) containing a constituent unit (x1) derived from vinyl acetate.

[2] The composite sheet for forming a protective film according to the above [1], wherein the content ratio of the constituent unit (x1) derived from vinyl acetate is 10 based on the total constituent unit of the acrylic polymer (X). ~75% by mass.

[3] The composite sheet for forming a protective film according to the above [1], wherein the energy ray polymerizable group is a (meth) acrylonitrile group.

The composite sheet for forming a protective film according to any one of the above aspects, wherein the energy ray-curable acrylic copolymer contains a constituent unit (x1) derived from vinyl acetate and contains An acrylic polymer (X) which is a structural unit (x2) of a functional group monomer, and an acrylic copolymer obtained by reacting a polymerizable compound (Y) having an energy ray-polymerizable group.

[5] The composite sheet for forming a protective film according to the above [4], wherein the value of α calculated by the following formula (2) is 20 or less; and the formula (2): α = [P] × [Q] × [R]/100

[In the formula (2), [P] represents the content ratio of the constituent unit (x2) derived from the monomer having a functional group with respect to 100% by mass of the total constituent unit of the acrylic polymer (X); 100 equivalents of the functional group of the functional group-containing monomer which the acrylic polymer (X) has, [Q] represents the equivalent of the polymerizable compound (Y); [R] represents the polymerizable compound (Y) The cardinality of the energy ray polymerizable group].

[6] The composite sheet for forming a protective film according to any one of the above [1], wherein the (A) polymer component and the (B) curable component are contained.

[7] The composite sheet for forming a protective film according to the above [6], wherein the film for forming a protective film contains a thermosetting component (B1) as a (B) curable component.

[8] The composite sheet for forming a protective film according to the above [7], wherein the protective film forming film is attached to the workpiece after the protective film forming film is attached to the workpiece, and the protective film forming composite sheet is not peeled off. The aforementioned adhesive sheet has the above protection at 130 ° C for 2 hours. The protective film obtained by curing the film for film formation has a gloss value of 40 or more.

[9] The composite sheet for forming a protective film according to any one of the above [1], wherein the substrate is a substrate containing a polypropylene film.

[10] A protective film-forming wafer which is provided with a protective film for forming a protective film for forming a composite sheet for forming a protective film according to any one of the above [1] to [9]. membrane.

[11] The wafer with a protective film according to [10] above, wherein the protective film has a gloss value of 40 or more as measured from the side opposite to the side having the wafer.

[12] A method for producing a wafer with a protective film, comprising the following steps (1) to (4): Step (1): attaching on the back surface of the workpiece, as described in any of [1] to [9] above. The step of forming a composite sheet for forming a protective film; the step (2): a step of cutting the workpiece; and the step (3): forming the film for forming a protective film without peeling off the adhesive sheet of the composite sheet for forming a protective film a step of hardening to form a protective film; and step (4): a step of picking up the processed film with the protective film obtained by the steps (1) to (3) to obtain a wafer with a protective film.

[13] A wafer with a protective film obtained by the manufacturing method as described in [12] above, wherein the wafer from the protective film is opposite to the side having the wafer The measured protective film has a gloss value of 40 or more.

When the composite sheet for forming a protective film of the present invention is used for cutting a workpiece such as a wafer, the effect of preventing the penetration of cutting water into the film for forming a protective film or the film between the protective film and the adhesive layer is high, and the pick-up during wafer manufacturing is adapted. The composite sheet for protective film formation of a wafer with a protective film excellent in visibility of a laser printed portion on the surface of a protective film is excellent.

1a, 1b, 1c, 2a, 2b, 2c‧‧‧ Composite film for forming a protective film (composite sheet)

10, 10a‧‧‧Adhesive tablets

11‧‧‧Substrate

12‧‧‧Adhesive layer

12a‧‧‧ hardened area

13‧‧‧Energy line shielding

20‧‧‧film for protective film formation

31‧‧‧

41‧‧‧The frame is followed by an adhesive layer

1 is a cross-sectional view showing a configuration of a composite sheet for forming a protective film of the present invention, which is a composite sheet for forming a protective film according to the first to third embodiments.

Fig. 2 is a cross-sectional view showing a configuration of a composite sheet for forming a protective film according to a fourth to sixth embodiment of the present invention.

Form of implementing the invention

In the description of the present specification, the weight average molecular weight (Mw) of the resin component such as the acrylic polymer or the energy ray-curable acrylic copolymer is a standard polyphenylene measured by a gel permeation chromatography (GPC) method. The value converted from ethylene is specifically a value measured based on the method described in the examples.

In addition, the glass transition temperature (Tg) of the resin component such as an acrylic polymer is converted into a Celsius by the glass transition temperature (Tg _K ) expressed by the absolute temperature (unit: K) calculated by the following formula (1). The value of temperature (unit: °C).

[In the above formula (1), W ₁ , W ₂ , W ₃ , W ₄ ... represent the mass fraction (% by mass) of the monomer component constituting the resin component, and Tg ₁ , Tg ₂ , Tg ₃ , Tg ₄ ... represent The glass transition temperature (unit: K) of the homopolymer of each monomer component constituting the resin component.

In the present specification, for example, the term "(meth)acrylate" is used as a term indicating both "acrylate" and "methacrylate", and the same applies to other similar terms.

Moreover, the "energy line" means, for example, an ultraviolet ray or an electron beam, and is preferably ultraviolet ray.

[Composite sheet for forming a protective film]

The composite sheet for forming a protective film of the present invention (hereinafter also referred to simply as "composite sheet") has a film for forming an adhesive sheet and a protective film, and the adhesive sheet has a substrate and an adhesive layer and contains hardening in the adhesive layer. In the region, the film for forming a protective film is directly laminated on the hardened region in the adhesive layer.

Fig. 1 and Fig. 2 are views showing an example of the configuration of the composite sheet of the present invention, and a cross-sectional view of the composite sheet of the present embodiment.

As shown in Fig. 1 and Fig. 2, the composite sheet of the present invention has a film for forming a protective film 20 directly laminated in the adhesive layer 12 from the viewpoint of improving the gloss value of the protective film and improving the mark adaptability. The structure on the hardened region 12a.

Furthermore, the composite sheet of the present invention may be in the form of a long strip or a single leaf label.

In the present invention, the hardened region 12a in the adhesive layer 12 is a region where the surface of the adhesive layer 12 is hardened by irradiation with an energy ray or the like when the adhesive layer 12 is viewed in plan.

In the composite sheet of the present invention, the hardened region 12a can be formed on the surface of the adhesive layer 12 at least at the position where the film for forming the protective film 20 is laminated. Therefore, the surface of the adhesive layer 12 on which the protective film forming film 20 is not laminated is also included, and the hardened region 12a may be formed on the entire surface of the adhesive layer 12.

The hardened region 12a can be formed by hardening a part or all of the adhesive layer 12 by irradiating an energy ray to the surface of the adhesive layer 12 in the vertical direction. By irradiating the energy ray in this manner, the hardened region 12a is formed not only from the surface of the adhesive layer 12 but also from the surface to the inside of the adhesive layer 12 in the thickness direction.

Further, in the composite sheets 1a and 1b shown in Fig. 1, the hardened region 12a indicates the designated surface of the adhesive layer 12 and the entire surface of the adhesive layer 12 in the thickness direction from the surface. The composition.

However, in an embodiment of the composite sheet of the present invention, in the thickness direction of the adhesive layer 12, a cured region and an uncured region may be combined. That is, in the inner region of the adhesive layer 12 in the thickness direction from the designated surface of the adhesive layer 12, a portion close to the surface is hardened to form a hardened region, which is located below the hardened region and close to the substrate. The area is not hardened.

By forming a hardened region in the adhesive layer, the obtained composite sheet-forming wafer for forming a protective film is excellent in pick-up property at the time of manufacture, and the glossiness of the protective film is high, and the laser printing portion on the surface of the protective film can be visually recognized. Excellent wafer with protective film.

Further, the hardened region 12a preferably has the same shape as the film for forming a protective film 20, but may have a shape larger than that of the film 20 for forming a protective film, and completely includes the shape of the film 20 for forming a protective film.

The irradiation of the energy ray may be performed from the side of the substrate 11 or from the side of the film 20 for forming a protective film, or may be performed from both sides. In addition, when the energy ray irradiation is performed before bonding the film 20 for forming a protective film and the adhesive sheet 10, it may be performed from the surface side to which the film 20 for protective film formation is bonded.

As an embodiment of the composite sheet of the present invention, the adhesive sheet 10 including the substrate 11 and the adhesive layer 12 and the film for forming a protective film are provided as shown in the first (a) to (c) drawings. 20 composite sheets 1a, 1b, 1c.

The composite sheet 1a of the first embodiment (a) has a configuration in which a part of the adhesive layer 12 is cured to form a cured region 12a, and the protective film forming film 20 is directly laminated on the cured region 12a.

The adhesive layer 12 on the exposed surface other than the hardened region 12a of the composite sheet 1a can be fixed to a frame such as a ring frame in order to maintain high adhesion.

Further, as in the composite sheet 1b of Fig. 1(b), the entire region of the adhesive layer 12 may be cured to form the cured region 12a, and the protective film forming film 20 may be directly laminated on the entire surface of the adhesive layer 12. Composition. In the composite sheet 1b, the film 20 for forming a protective film has the same shape as the adhesive sheet 10.

The composite sheet of the present invention may be configured as a composite sheet 1b in which the film 20 for forming a protective film is adjusted to have a shape substantially the same as that of a workpiece such as a semiconductor wafer or may completely include the shape of the workpiece. Further, the composite sheet of the present invention may be a composite sheet 1a in which an adhesive sheet 10 larger than the protective film forming film 20 is provided.

Further, as in the composite sheet 1c of the first (c), the energy ray shielding layer 13 is provided by printing on one of the boundaries of the substrate 11 and the adhesive layer 12, and the energy ray is irradiated from the substrate 11 side. The inside of the adhesive layer 12 can be formed by dividing the hardened region 12a into an uncured region.

Furthermore, as an embodiment of the composite sheet of the present invention, it is intended to improve the adhesion of the frame when it is attached to a frame such as a ring frame, as shown in Figures 2(a) to (b). It is to be noted that a configuration in which the post-layer 31 is provided on the outer peripheral portion of the composite sheet can be employed.

The composite sheet 2a of Fig. 2(a) has a structure in which a pattern subsequent layer 31 is provided on the surface of the adhesive film layer 12 on which the protective film forming film 20 is not laminated.

In addition, the composite sheet 2b of the second embodiment (b) has the same shape as the adhesive film 10, and has an outer peripheral portion on the surface of the protective film forming film 20, and is provided with a post-layer 31. Composition.

The carrier back layer 31 can be formed of a double-sided adhesive sheet or an adhesive having a substrate (core material).

The base material (core material) which is a double-sided adhesive sheet which can be used as a material for forming the squeegee layer 31 can be the same as the base material 11 of the adhesive sheet 10, and for example, a polyester film or a poly A propylene film, a polycarbonate film, a polyimide film, a fluororesin film, a liquid crystal polymer film or the like is preferably a polypropylene film.

As an adhesive which can form a material for forming the subsequent layer 31 of the form, the energy ray-curable adhesive can be classified according to the function of the adhesive. An adhesive having a surface unevenness, a heat-expandable adhesive, and the like are classified according to the main resin in the adhesive, and examples thereof include an acrylic adhesive, a rubber adhesive, a polyoxygen adhesive, and an urethane adhesive. Adhesive, vinyl ether adhesive, etc.

The thickness of the pattern subsequent layer 31 is preferably from 1 to 80 μm, more preferably from 5 to 60 μm, still more preferably from 10 to 40 μm.

Further, as an embodiment of the composite sheet of the present invention, as shown in Fig. 2(c), a composite sheet 2c having an adhesive layer in which a plurality of layers are laminated may be used.

In other words, the composite sheet 2c of the second (c) has a pressure-sensitive adhesive layer 12 directly formed on the cured film-containing film 12a in addition to the protective film-forming film 20, and a frame is provided between the substrate 11 and the adhesive layer 12. Next, the adhesive layer 41 is used.

By arranging the profiler and then using the adhesive layer 41, in the region in which the profiler is followed by the adhesive layer 41 in a plan view, when the region where the adhesive layer 12 does not exist is followed by the frame of the ring frame or the like, The adhesion of the frame and the adhesion of the interface between the film 20 for forming a protective film and the adhesive layer 12 can be controlled. As a result, when the wafer is manufactured using the composite sheet 2c, the pick-up workability can be improved.

As the adhesive which can be used as the material for forming the adhesive layer 41 and the adhesive layer 41, the same adhesive as the above-mentioned material for forming the adhesive layer 31 can be used, and it is preferable to exhibit the specific adhesive layer 12. Adhesive adhesive with high adhesion.

The thickness of the adhesive layer 41 for the frame is preferably 1 to 50 μm, more preferably 3 to 40 μm, and particularly preferably 3 to 30 μm.

Further, in the composite sheet of the present invention, the surface of the protective film forming film 20, the surface of the adhesive layer 12 on which the protective film forming film 20 is not laminated to expose the surface, the surface of the post-layer layer 31, and The pattern in which the adhesive layer 12 is not laminated to expose the surface is followed by the surface of the adhesive layer 41, and a release sheet may be further provided.

The release sheet may be one in which a release agent is applied to at least one surface of the base material for a release sheet, and a release treatment is applied.

The base material for a release sheet is the same as the resin film which comprises the base material mentioned later.

Examples of the release agent include an alkyd release agent, a polyoxymethylene release agent, a fluorine release agent, an unsaturated polyester release agent, a polyolefin release agent, and a wax release agent. Among these, from the viewpoint of heat resistance, an alkyd-based release agent, a polyoxymethylene-based release agent, and a fluorine-based release agent are preferable.

The thickness of the release sheet is not particularly limited, and is preferably from 10 to 500 μm, more preferably from 15 to 300 μm, still more preferably from 20 to 200 μm.

Hereinafter, the details of the substrate, the adhesive layer, and the film for forming a protective film which constitute the composite sheet of the present invention will be described.

<Substrate>

Examples of the substrate of the adhesive sheet used in the present invention include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride copolymer. Film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionic polymer Resin film, ethylene a resin film such as a (meth)acrylic copolymer film, an ethylene-(meth)acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, or a fluororesin film.

Furthermore, these resin films may also be crosslinked films.

Moreover, the base material used in the present invention may be a single-layer film composed of one type of resin film, or a laminated film in which two or more kinds of resin films are laminated. Further, as the substrate, a colored film can also be used.

Among these, a base material containing a polypropylene film is preferable because it is excellent in heat resistance, has flexibility in expansion for appropriate flexibility, and is easy to maintain pick-up property.

Further, the structure of the substrate including the polypropylene film may be a single layer structure composed only of a polypropylene film, or may be a multiple layer structure composed of a polypropylene film and another resin film.

The film for forming a protective film is thermosetting, and when the film for forming a protective film is thermally cured before being peeled off from the adhesive sheet, the substrate has heat resistance, and the damage of the substrate due to heat is suppressed, thereby suppressing the semiconductor. The occurrence of a bad condition in the process of the device.

The thickness of the substrate is preferably from 10 to 500 μm, more preferably from 15 to 300 μm, still more preferably from 20 to 200 μm.

<Adhesive layer>

As shown in Figs. 1 and 2, the adhesive layer 12 of the adhesive sheet 10 used in the present invention contains a hardened region 12a in the adhesive layer.

In the present invention, the hardened region 12a in the adhesive layer means a region which is hardened by irradiating the adhesive layer with an energy ray.

Further, the degree of progress of the hardening reaction of the adhesive layer in the hardened region 12a is preferably 50% or more, preferably 70% or more, more preferably 90% or more, and still more preferably completely cured.

By forming a hardened region in the adhesive layer, the obtained composite sheet for forming a protective film is excellent in pick-up property at the time of wafer production. Further, the protective film formed of the composite sheet has a high gloss value, and by using the composite sheet, a wafer with a protective film excellent in visibility of a laser printed portion on the surface of the protective film can be produced.

The reason why the pick-up property at the time of wafer production is improved by using the composite sheet of the present invention is judged to be that the fluidity of the hardened region in the adhesive layer is lowered.

Moreover, the reason why the glossiness value of the protective film formed by the composite sheet of the present invention is increased is determined because the cured region in the adhesive layer is kept low in fluidity during heating, so that the film for forming a protective film is used. The surface smoothness of the hardened region in the adhesive layer can also be maintained during the heat curing to form the protective film.

The thickness of the adhesive layer is preferably from 1 to 100 μm, more preferably from 3 to 50 μm, still more preferably from 5 to 25 μm.

The adhesive layer is a layer formed of an adhesive composition containing an energy ray-curable acrylic copolymer which is an acrylic polymer containing a constituent unit (x1) derived from vinyl acetate ( X) The energy ray polymerizable group is introduced.

In addition to the above-mentioned energy ray-curable acrylic copolymer, the adhesive composition preferably contains a photopolymerization initiator from the viewpoint of efficiently performing a curing reaction in a short period of time, and improves the formed adhesive layer. From the viewpoint of cohesive force and adhesion, it is preferred to further contain a crosslinking agent.

Hereinafter, each component contained in the adhesive composition forming the adhesive layer will be described in detail.

[Energy curing type acrylic copolymer]

The energy ray-curable acrylic copolymer used in the present invention is an acrylic copolymer in which an energy ray-polymerizable group is introduced to an acrylic polymer (X) containing a constituent unit (x1) derived from vinyl acetate.

Since the energy ray-curable acrylic copolymer is contained in the adhesive composition constituting the adhesive layer, the hardened region can be formed in the adhesive layer by irradiation of the energy ray.

The energy ray-polymerizable group-based energy-polymerizable carbon-carbon double bond-containing group may, for example, be a (meth) acrylonitrile group or a vinyl group. Among these, from the viewpoint of easy introduction of the energy ray polymerizable group, a (meth) acrylonitrile group is preferred.

The energy ray polymerizable group may be introduced into the main chain of the acrylic polymer (X) or may be introduced into the side chain.

Further, the energy ray polymerizable group may be bonded to the acrylic polymer (X) via an alkylene group, an alkoxy group, a polyalkylene group or the like.

The weight average molecular weight (Mw) of the energy ray-hardening type acrylic copolymer is preferably from 100,000 to 1.5 million, more preferably from 200,000 to 1,200,000, particularly preferably from 300,000 to 1,000,000, and more preferably from 400,000 to 800,000. .

When the Mw is 100,000 or more, a protective film having a high gloss value can be formed. Further, it is possible to suppress the phenomenon that the adhesive layer is transferred to the surface of the film for forming a protective film to contaminate the surface of the film for forming a protective film.

On the other hand, when the Mw is 1.5 million or less, the adhesion between the adhesive layer and the film for forming a protective film is good, and the phenomenon that the cutting water penetrates into the adhesive layer and the protective film forming film or the protective film during cutting can be suppressed. .

The content of the energy ray-curable acrylic copolymer is preferably from 60 to 100% by mass, more preferably from 70 to 99.9% by mass, based on the total amount of the adhesive composition (100% by mass of the active ingredient (solid content)). It is 80 to 99% by mass, and more preferably 90 to 98% by mass.

The energy ray-curable acrylic copolymer is preferably an acrylic copolymer obtained by reacting an acrylic polymer (X) with a polymerizable compound (Y) having an energy ray-polymerizable group, and more preferably contains a vinyl acetate. The constituent unit (x1) and an acrylic polymer (X) derived from the functional group-containing monomer (x2) and an acrylic copolymer obtained by reacting the polymerizable compound (Y) having an energy ray-polymerizable group.

The acrylic polymer (X) reacts with a substituent in the polymerizable compound (Y), and the energy ray polymerizable group of the polymerizable compound (Y) is introduced into the main chain and the side chain of the acrylic polymer (X). At least one of them becomes an energy ray-hardening acrylic copolymer.

Hereinafter, the acrylic polymer (X) and the polymerizable compound (Y) will be described.

(acrylic polymer (X))

The acrylic polymer (X) contains a constituent unit (x1) derived from vinyl acetate.

By using the acrylic polymer (X) containing the structural unit (x1) derived from vinyl acetate, the adhesion between the formed adhesive layer and the film for forming a protective film can be kept good, and the penetration of cutting water during cutting can be suppressed. A phenomenon between a film for film formation or a protective film and an adhesive layer. Further, the formed adhesive layer containing the hardened region maintains low fluidity during heating, and when the film for forming a protective film is heat-cured, the surface smoothness of the adhesive layer can be maintained, and the protective film can be improved. Gloss value. In addition, the pick-up property can be made good.

The content ratio of the constituent unit (x1) is preferably from 10 to 75% by mass, more preferably from 15 to 70% by mass, even more preferably from 25 to 70% by mass based on the total constituent unit (100% by mass) of the acrylic polymer (X). 65% by mass, and more preferably 30 to 60% by mass.

When the content ratio of the constituent unit (x1) is 10% by mass or more, the adhesion between the formed adhesive layer and the film for forming a protective film can be kept good. Further, the formed adhesive layer containing the hardened region maintains low fluidity during heating, and when the film for forming a protective film is heat-cured, the surface smoothness of the adhesive layer can be maintained, and the protective film can be improved. Gloss value. In addition, the pick-up property can be made good.

On the other hand, when the content ratio is 75% by mass or less, the adhesion between the pressure-sensitive adhesive layer and the protective film forming film or the protective film can be suppressed from being lowered, and the cutting water can be prevented from penetrating into the protective film forming film or the protective film during cutting. The phenomenon between the layers of adhesive.

The acrylic polymer (X) preferably contains both the constituent unit (x1) and the constituent unit (x2) derived from the functional group-containing monomer.

The functional group which the structural unit (x2) has is preferably a group which reacts with a substituent which the polymerizable compound (Y) has.

Examples of the functional group include a hydroxyl group, a carboxyl group, an epoxy group, an amine group, a cyano group, a ketone group, a ring group containing a nitrogen atom, and an alkoxyalkyl group.

Examples of the functional group-containing monomer constituting the structural unit (x2) include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an epoxy group-containing monomer, an amine group-containing monomer, and a cyano group-containing monomer. A monomer, a ketone group-containing monomer, a monomer having a ring containing a nitrogen atom, a monomer containing an alkoxyalkyl group, or the like.

These single system containing a functional group may be used alone or in combination of two or more.

Among these, a monomer having a hydroxyl group is preferred.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and (meth)acrylic acid 2. - Hydroxybutyl (meth)acrylates such as hydroxybutyl ester, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol Wait.

Among these, 2-hydroxyethyl (meth)acrylate is preferred.

Examples of the carboxyl group-containing monomer include (meth)acrylic acid, maleic acid, fumaric acid, and itaconic acid.

Examples of the epoxy group-containing monomer include an epoxy group-containing (meth) acrylate and a non-acrylic epoxy group-containing monomer.

Examples of the epoxy group-containing (meth) acrylate include glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, and (meth)acrylic acid (3, 4). -Epoxycyclohexyl)methyl ester, 3-epoxycyclo-2-hydroxypropyl (meth)acrylate, and the like.

Moreover, examples of the non-acrylic epoxy group-containing monomer include butyl crotonate and allyl epoxypropyl ether.

These single system containing a functional group may be used alone or in combination of two or more.

The content ratio of the constituent unit (x2) is preferably from 1 to 35% by mass, more preferably from 5 to 30% by mass, even more preferably from 7 to 7% by mass based on the total constituent unit (100% by mass) of the acrylic polymer (X). 27% by mass, particularly preferably 10 to 25% by mass.

When the content ratio of the structural unit (x2) is 1% by mass or more, the reaction point with the polymerizable compound (Y) increases, and the amount of the polymerizable compound (Y) can be increased. As a result, an adhesive layer having a higher hardenability can be formed.

On the other hand, when the content ratio of the constituent unit (x2) is 35% by mass or less, a sufficient application period can be ensured in the step of applying a solution of the adhesive composition as a coating liquid to form an adhesive layer. Further, it is possible to suppress the degree of hydrophilicity of the formed adhesive layer from becoming excessive, and to prevent the cutting water from infiltrating into the film between the adhesive layer and the protective film or the protective film.

The acrylic polymer (X) preferably further contains a constituent unit derived from an alkyl (meth)acrylate from the viewpoint of improving the adhesion of the adhesive layer and improving the adhesion between the adhesive layer and the film for forming a protective film. (x3).

The (meth)acrylic acid alkyl ester constituting the structural unit (x3) is not particularly limited as long as it is a monomer copolymerizable with the functional group-containing monomer and vinyl acetate, but the adhesive layer is improved. From the viewpoint of improving the adhesion between the adhesive layer and the film for forming a protective film, it is preferably an alkyl (meth)acrylate having an alkyl group having 1 to 18 carbon atoms or a cyclic skeleton. The acrylate is preferably an alkyl (meth) acrylate having an alkyl group having 1 to 18 carbon atoms.

Further, the number of carbon atoms of the alkyl group of the (meth)acrylic acid alkyl ester is preferably from 1 to 18, more preferably from 1 to 12, still more preferably from 4 to 10.

Examples of the alkyl (meth)acrylate having an alkyl group having 1 to 18 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (methyl). Butyl acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, octadecyl (meth)acrylate, and the like.

Examples of the (meth) acrylate having a cyclic skeleton include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, and acrylic acid. Ester, dicyclopentanyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, decyl acrylate, and the like.

These single systems may be used alone or in combination of two or more.

Among these, from the viewpoint of improving the adhesion of the pressure-sensitive adhesive layer and improving the adhesion between the pressure-sensitive adhesive layer and the film for forming a protective film, butyl (meth)acrylate or (meth)acrylic acid 2 is preferred. Ethylhexyl ester, more preferably 2-ethylhexyl (meth)acrylate.

The content ratio of the constituent unit (x3) is preferably from 10 to 75% by mass, more preferably from 15 to 70% by mass, even more preferably from 20 to 70% by mass based on the total constituent unit (100% by mass) of the acrylic polymer (X). 65% by mass, and more preferably 25 to 60% by mass.

Further, the acrylic polymer (X) may contain other constituent units other than the above constituent units (x1) to (x3).

Examples of the monomer derived from another constituent unit include monomers such as acrylonitrile and styrene.

The total content of the constituent units other than the constituent units (x1) to (x3) is preferably 0 to 25% by mass, more preferably 0 to 25% by mass based on the total constituent unit (100% by mass) of the acrylic polymer (X). It is 0 to 15% by mass, particularly preferably 0 to 10% by mass, and more preferably 0 to 2% by mass.

Further, the copolymerization form of the acrylic polymer (X) is not particularly limited, and may be any of a block copolymer, a random copolymer, and a graft copolymer.

The weight average molecular weight (Mw) of the acrylic polymer (X) is preferably from 100,000 to 1,500,000, more preferably from 200,000 to 1,200,000, and particularly preferably from 300,000 to 1,000,000.

Further, acrylic polymerization is carried out from the viewpoint of adjusting the adhesion of the pressure-sensitive adhesive layer to an appropriate range and maintaining the adhesion between the formed adhesive layer containing the hardened region and the film for forming a protective film, and the balance of the pick-up property. The glass transition temperature (Tg) of the substance (X) is preferably -50 to 0 ° C, more preferably -40 to -10 ° C.

The method for synthesizing the acrylic polymer (X) is not particularly limited, and for example, a solution polymerization method in the presence of a solvent, a polymerization initiator, a chain transfer agent, or the like, or an emulsifier or a polymerization initiator can be used. It is produced by a method of performing emulsion polymerization in an aqueous system in the presence of a chain transfer agent or a dispersant. Further, in the polymerization method, additives such as a tackifier, a wetting agent, a leveling agent, and an antifoaming agent may be added as needed.

The polymerization reaction is preferably carried out at a temperature of 60 to 100 ° C for 2 to 8 hours.

The concentration of the raw material monomers during the polymerization is usually from 30 to 70% by mass, preferably from 40 to 60% by mass.

Examples of the polymerization initiator to be used in the polymerization include persulfate such as potassium persulfate or ammonium persulfate, 2,2'-azobisisobutyronitrile, and 2,2'-azobis (2, a combination of an azo compound such as 4-dimethylvaleronitrile or a peroxide such as hydrogen peroxide, benzamidine peroxide or lauryl peroxide, ammonium persulfate, sodium sulfite or sodium sulfite; A redox polymerization initiator or the like.

The amount of the polymerization initiator added is preferably 0.2 to 2 parts by mass, more preferably 0.3 to 1 part by mass, per 100 parts by mass of the total amount of the raw material monomers.

Examples of the chain transfer agent used in the polymerization include alkyl mercaptans such as octyl mercaptan, mercapto mercaptan, mercapto mercaptan, and dodecyl mercaptan; octyl mercaptoacetate; Mercaptoacetate such as ester, thioglycolic acid-2-ethylhexyl ester, β-mercaptopropionic acid-2-ethylhexyl ester, 2,4-diphenyl-4-methyl-1-pentene, 1 -Methyl-4-isopropylidene-1-cyclohexene, and the like.

Among these, thioglycolate, 2,4-diphenyl-4-methyl-1-pentene, and 1-methyl-4-isopropylidene-1-cyclohexene are preferred.

The amount of the chain transfer agent added is preferably 0.001 to 3 parts by mass based on 100 parts by mass of the total amount of the raw material monomers.

(Polymerizable compound (Y))

The polymerizable compound (Y) is a compound having a polymerizable group containing an energy ray-polymerizable carbon-carbon double bond, and is reactive with the acrylic polymer (X), and is mainly composed of the main chain and side of the acrylic polymer (X). A compound of the polymerizable group is introduced into at least one of the chains.

The polymerizable compound (Y) preferably has a substituent reactive with a functional group of the structural unit (x2) of the acrylic polymer (X), and has 1 to 5 energy ray polymerization per molecule. A compound having a polymerizable group containing a carbon-carbon double bond.

The substituent to be reacted with the functional group of the acrylic polymer (X) may, for example, be an isocyanate group, a carboxyl group or an epoxy group, and is preferably an isocyanate group.

In addition, examples of the polymerizable group of the energy ray-polymerizable carbon-carbon double bond include a (meth) acrylonitrile group and a vinyl group, and a (meth) acryl fluorenyl group is preferred.

Specific examples of the polymerizable compound (Y) include (meth) propylene methoxyethyl isocyanate, m-isopropenyl-α, α-dimethylbenzyl isocyanate, and (meth) propylene decyl isocyanate. , allyl isocyanate, glycidyl (meth)acrylate, (meth)acrylic acid, and the like.

These polymerizable compounds (Y) may be used alone or in combination of two or more.

Among these, the acrylic polymer (X) and the polymerizable group are used from a substituent having a preferred isocyanate group as a functional group reactive with a constituent unit (x2) of the acrylic polymer (X). From the viewpoint of a suitable compound, (meth)acryloxyethyl isocyanate is preferred.

In the method of synthesizing the energy ray-curable acrylic copolymer, for example, when the polymerizable compound (Y) having an isocyanate group is introduced into the acrylic polymer (X) having a hydroxyl group, an organic solution such as ethyl acetate may be used. In the case of using a catalyst such as dibutyltin laurate, the reaction is carried out at a temperature of about room temperature for about 24 hours under normal pressure.

The blending amount of the polymerizable compound (Y) relative to the number of functional groups of the 100 equivalents of the acrylic polymer (X) is higher from the viewpoint of improving the adaptability of the laser marking of the formed protective film. Preferably, it is 20 to 100 equivalents, more preferably 30 to 95 equivalents, and particularly preferably 40 to 90 equivalents, and more preferably 55 to 85 equivalents.

In addition, the blending amount of the polymerizable compound (Y) with respect to 100 parts by mass of the acrylic polymer (X), the laser marking suitability from the formed protective film, and the formation of the adhesive layer and the protective film are improved. From the viewpoint of the adhesion of the film or the protective film, it is preferably from 1 to 40 parts by mass, more preferably from 5 to 35 parts by mass, particularly preferably from 10 to 30 parts by mass, particularly preferably from 14 to 25 parts by mass.

In addition, the relationship between the amount of the blend of the acrylic polymer (X) and the polymerizable compound (Y) is preferably 20 or less by the following formula (2); and the formula (2): α =[P]×[Q]×[R]/100

In the above formula (2), [P] represents the content ratio of the constituent unit (x2) derived from the functional group-containing monomer with respect to 100% by mass of the total constituent unit of the acrylic polymer (X); 100 equivalents of the functional group of the functional group-containing monomer which the acrylic polymer (X) has, [Q] represents the equivalent of the polymerizable compound (Y); [R] represents the polymerizable compound (Y) The cardinality of the energy ray polymerizable group.

The value of α calculated by the formula (2) is an index of the adhesion between the formed adhesive layer containing the cured region and the protective film forming film or the protective film, and the smaller the value, the higher the adhesion, and the crystal When cutting a workpiece such as a circle, the effect of inhibiting the penetration of cutting water into the film for forming a protective film or the phenomenon between the protective film and the adhesive layer is high.

The value of α is preferably 20 or less, more preferably 18 or less, still more preferably 17 or less, still more preferably 16 or less. Moreover, from the viewpoint of improving the pick-up property, it is preferably 1 or more, and more preferably 5 or more.

On the other hand, in general, when the adhesion between the pressure-sensitive adhesive layer and the film for forming a protective film or the protective film is to be improved, the pick-up property tends to be lowered.

However, in the present invention, as the material for forming the adhesive layer, since the energy ray-curable acrylic copolymer containing the constituent unit (x1) derived from vinyl acetate is used, even if the value of α is low, the pickup is excellent. Adaptability.

Further, in the present invention, by using an energy ray-curable acrylic copolymer containing a constituent unit (x1) derived from vinyl acetate, the fluidity at the time of heating of the formed adhesive layer containing the hardened region can be kept low. On the other hand, when the film for forming a protective film is heat-cured, the surface smoothness of the adhesive layer can be maintained, and as a result, the gloss value of the formed protective film can be improved.

[Photopolymerization initiator]

The adhesive composition used in the present invention preferably further contains a photopolymerization initiator.

By containing a photopolymerization initiator, when the adhesive layer is irradiated with an energy ray to harden the adhesive layer, the polymerization hardening time can be shortened, and even if the amount of light irradiation is small, the adhesive layer can be hardened to form a hardened region. .

Examples of the photopolymerization initiator include a benzoin compound, an acetophenone compound, a mercaptophosphine oxide compound, and ferroceneation. A photoinitiator such as a compound, a thioxanthone compound or a peroxide compound, or a photo sensitizer such as an amine or a hydrazine.

Specific examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzyl group II. Phenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, bibenzyl, hydrazine, β-chloropurine, 2,4,6-trimethylbenzhydrylbiphenyl Phosphine oxide and the like.

These photopolymerization initiators can be used alone or in combination of two or more.

The content of the photopolymerization initiator is preferably 0.1 to 10 with respect to 100 parts by mass of the energy ray-curable acrylic copolymer from the viewpoint of sufficiently improving the curing reaction, improving the pick-up property, and suppressing the formation of the residue. The mass portion is more preferably 1 to 7 parts by mass, particularly preferably 2 to 5 parts by mass.

[crosslinking agent]

The adhesive composition used in the present invention preferably further contains a crosslinking agent.

By including the crosslinking agent, the network structure is formed by crosslinking reaction with the functional group of the acrylic polymer (X), whereby the cohesive force of the formed adhesive layer can be improved, and the adhesion can be controlled.

Examples of the crosslinking agent include an organic polyvalent isocyanate compound, an organic polyvalent epoxy compound, and an organic polyvalent imine compound.

Examples of the organic polyvalent isocyanate compound include an aromatic polyvalent isocyanate compound, an aliphatic polyvalent isocyanate compound, an alicyclic polyvalent isocyanate compound, and organic polyvalents thereof. a terpolymer of an isocyanate compound, a terminal isocyanate urethane prepolymer obtained by reacting the organic polyvalent isocyanate compound with a polyol compound, and the like.

Specific examples of the organic polyvalent isocyanate compound include a toluene diisocyanate compound such as 2,4-toluene diisocyanate or 2,6-toluene diisocyanate, and 1,3-benzenedimethyl diisocyanate and 1,4. a xylene diisocyanate compound such as xylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate , hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, isocyanate isocyanate, and the like Polyol adducts and the like.

Examples of the organic polyvalent epoxy compound include 1,3-bis(N,N'-diepoxypropylaminomethyl)cyclohexane, N,N,N',N'-tetraepoxy. Propyl-m-phthaldimethyldiamine, ethylene glycol diepoxypropyl ether, 1,6-hexanediol diepoxypropyl ether, trimethylolpropane diepoxypropyl ether, bicyclo Oxypropyl aniline, diepoxypropylamine, and the like.

Examples of the organic polyvalent imine compound include N,N'-diphenylmethane-4,4'-bis(1-azitidinecarboxamide), and trimethylolpropane-tri-β-oxime. Propidyl propionate, tetramethylolmethane-tri-β-aziridinyl propionate and N,N'-toluene-2,4-bis(1-aziridinium carboxamide) triethylene melamine Wait.

The content of the crosslinking agent is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, even more preferably 0.3 to 5 parts by mass, per 100 parts by mass of the energy ray-curable acrylic copolymer.

[Other additives]

Further, the adhesive composition used in the present invention may further contain other additives such as a tackifier resin, an antioxidant, a stabilizer, a softener, a filler, a pigment, and a dye.

Examples of the tackifier resin include a rosin-based resin, a hydrogenated rosin-based resin, a terpene-based resin, a hydrogenated terpene-based resin, a C5-based petroleum resin obtained by copolymerizing a C5 fraction, and a hydrogenated petroleum resin of a C5-based petroleum resin. A C9-based petroleum resin obtained by copolymerizing a C9 fraction, a hydrogenated petroleum resin of a C9-based petroleum resin, or the like.

The respective contents of the other additives are preferably 0 to 30% by mass, more preferably 0 to 20% by mass, even more preferably 0 to 20% by mass, based on the total amount of the adhesive composition (100% by mass of the active ingredient (solid content)). ~10% by mass, and more preferably 0 to 4% by mass.

Further, the adhesive composition used in the present invention may contain other resin components (polymers) other than the energy ray-curable acrylic copolymer.

The total content of the other resin components is preferably 0 to 40 parts by mass, more preferably 0 to 20 parts by mass, even more preferably 0 to 10 parts by mass, per 100 parts by mass of the energy ray-curable acrylic copolymer. More preferably, it is 0 to 4 parts by mass.

<Method of Manufacturing Adhesive Sheet>

The method for producing the pressure-sensitive adhesive sheet is not particularly limited. For example, a solution of the pressure-sensitive adhesive composition can be prepared by adding an organic solvent to each of the above components. Then, a solution of the adhesive composition is applied onto a substrate by a known method to form a coating film, and the coating film is dried to form an adhesive layer.

Further, a solution of the adhesive composition is applied onto the release sheet, an adhesive layer is formed on the release sheet, and a substrate is laminated on the adhesive layer, and may be an adhesive sheet with a release sheet. Further, when the adhesive sheet is used, the release sheet is removed, and a film for forming a protective film is laminated on the adhesive layer on the exposed surface.

Examples of the organic solvent include toluene, ethyl acetate, and methyl ethyl ketone. Further, the solid content concentration of the solution of the adhesive composition is preferably from 10 to 80% by mass, more preferably from 25 to 70% by mass, even more preferably from 45 to 65% by mass.

Examples of the coating method of the solution of the adhesive composition include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method.

Further, the method of forming the hardened region in the formed adhesive layer is not particularly limited. For example, in the method for producing an adhesive sheet, an energy line such as ultraviolet rays may be irradiated from the side of the release sheet or the side of the substrate to cure the adhesive layer.

The illuminance of the ultraviolet ray to be irradiated is preferably from 100 to 250 mW/cm ² , and the amount of ultraviolet light is preferably from 350 to 700 mJ/cm ² .

By forming a hardened region in the adhesive layer as described above, it is possible to manufacture a composite sheet excellent in pick-up property at the time of wafer production. Moreover, the protective film formed using the composite sheet has a high gloss value, and the wafer with the protective film produced by using the composite sheet is excellent in visibility of the laser printed portion on the surface of the protective film.

<film for forming protective film>

The film for forming a protective film is not particularly limited, but preferably contains (A) a polymer component and (B) a curable component, and may further contain (C) a colorant, (D) a coupling agent, (E). ) Inorganic filler, (F) general purpose additive.

Hereinafter, the components (A) to (F) contained in the film for forming a protective film will be described.

[(A) Polymer component]

The term "polymer component" means a compound having a weight average molecular weight of 20,000 or more and having at least one repeating unit. When the (A) polymerizable component is contained in the film for forming a protective film, the film for forming a protective film is imparted with flexibility and film-forming property, and the sheet property shape maintainability is improved.

The weight average molecular weight (Mw) of the polymer component (A) is preferably 20,000 or more, more preferably 20,000 to 3,000,000, particularly preferably 50,000 to 2,000,000, and more preferably 100,000 to 1,500,000.

The content of the component (A) is preferably from 5 to 50% by mass, more preferably from 8 to 40% by mass, even more preferably from 10 to 30% by mass, based on the total amount (100% by mass) of the film for forming a protective film. Good is 12~25% by mass.

The (A) polymer component is preferably an (A1) acrylic polymer, and a polyester other than the component (A1), a phenoxy resin, a polycarbonate, a polyether, a polyurethane, or a poly (A2) non-acrylic polymer such as a siloxane or a rubber-based polymer.

These polymer components may be used alone or in combination of two or more.

((A1) acrylic polymer)

(A1) The weight average molecular weight (Mw) of the acrylic polymer is preferably from 20,000 to 3,000,000, more preferably from 100%, from the viewpoint of imparting flexibility and film-forming properties to the film for forming a protective film. 1.5 million, especially good for 150,000 to 1.2 million, and even better for 250,000 to 1 million.

(A1) The glass transition temperature (Tg) of the acrylic polymer is obtained from the viewpoint of the adhesion of the film for forming a protective film or the adherend of the protective film obtained by curing the film, and the use of the composite sheet. The reliability of the wafer with the protective film is preferably -60 to 50 ° C, more preferably -50 to 40 ° C, particularly preferably -40 to 30 ° C, and more preferably -35 to 20 ° C. .

The (A1) acrylic polymer may, for example, be a polymer having a (meth)acrylic acid alkyl ester as a main component, and specifically, preferably contains a (meth) group derived from an alkyl group having 1 to 18 carbon atoms. The acrylic polymer of the structural unit (a1) of the alkyl acrylate is more preferably an acrylic copolymer containing both the constituent unit (a1) and the constituent unit (a2) derived from the functional group-containing monomer.

The component (A1) may be used alone or in combination of two or more.

Further, when the component (A1) is a copolymer, the form of the copolymer may be any of a block copolymer, a random copolymer, an alternating copolymer, and a graft copolymer.

(constituting unit (a1))

The carbon number of the alkyl group of the alkyl (meth)acrylate constituting the unit (a1) is preferably from 1 to 18, more preferably from the viewpoint of imparting flexibility and film-forming properties to the film for forming a protective film. It is 1~12, especially 1~8.

Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylic acid. Amyl ester, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate And (meth) methacrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, and the like.

Further, these (meth)acrylic acid alkyl esters may be used alone or in combination of two or more.

Among these, from the viewpoint of increasing the glossiness value of the protective film formed of the film for forming a protective film and improving the laser mark adaptability of the protective film, it is preferred to have an alkyl group having 4 or more carbon atoms. The alkyl (meth)acrylate is more preferably an alkyl (meth)acrylate having an alkyl group having 4 to 6 carbon atoms, particularly preferably butyl (meth)acrylate.

In view of the above, the content ratio of the constituent unit derived from the alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms is preferably the total structural unit (100% by mass) of the (A1) acrylic polymer. 1 to 70% by mass, more preferably 5 to 65% by mass, and particularly preferably 10 to 60% by mass.

Moreover, from the viewpoint of improving the reliability of the wafer with the protective film produced by using the composite sheet, an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms is preferable, and more preferably (methyl group). )Methyl acrylate.

In view of the above, the content ratio of the constituent unit derived from the alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms is preferably based on the total structural unit (100% by mass) of the (A1) acrylic polymer. It is 1 to 60% by mass, more preferably 3 to 50% by mass, and particularly preferably 5 to 40% by mass.

The content ratio of the constituent unit (a1) is preferably 50% by mass or more, more preferably 50 to 99% by mass, and particularly preferably 55 to 90%, based on the total structural unit (100% by mass) of the (A1) acrylic polymer. The mass% is particularly preferably 60 to 80% by mass.

(constituting unit (a2))

Examples of the functional group-containing monomer constituting the structural unit (a2) include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an epoxy group-containing monomer, an amine group-containing monomer, and a cyano group-containing monomer. A monomer, a ketone group-containing monomer, a monomer having a ring containing a nitrogen atom, a monomer containing an alkoxyalkyl group, or the like.

These single system containing a functional group may be used alone or in combination of two or more.

Among these, a monomer having a hydroxyl group is preferred.

The hydroxyl group-containing monomer is exemplified as the monomer having a functional group constituting the structural unit (x2), and is preferably 2-hydroxyethyl (meth)acrylate.

The monomer having a carboxyl group is exemplified as a monomer having a functional group constituting the structural unit (x2).

When a carboxyl group-containing monomer is used, a carboxyl group is introduced into the (A1) acrylic polymer, and when the energy ray-curable component is contained in the raw material composition of the film for forming a protective film as the (B) curable component, the component (B) The compatibility with the component (A) is increased.

In addition, when an epoxy-based thermosetting component is used as the curable component (B) to be described later, since the carboxyl group reacts with the epoxy group in the epoxy-based thermosetting component, it is preferably derived from a carboxyl group-containing group. The content of the structural unit of the monomer is small.

When an epoxy-based thermosetting component is used as the curable component (B), the content of the structural unit derived from the carboxyl group-containing monomer is higher than the total constituent unit (100% by mass) constituting the acrylic polymer (A1). Preferably, it is 0 to 10% by mass, more preferably 0 to 5% by mass, particularly preferably 0 to 2% by mass, and even more preferably 0% by mass.

The epoxy group-containing monomer is exemplified as the monomer having a functional group constituting the structural unit (x1), and is preferably an epoxy group-containing (meth) acrylate, more preferably ( Glycidyl methacrylate.

When the constituent unit of the monomer containing the epoxy group is contained in the constituent unit of the (A1) acrylic polymer, the glossiness of the protective film formed of the film for forming a protective film can be increased, and the thickness can be improved. Laser marking adaptability of the protective film.

The content ratio of the constituent unit derived from the epoxy group-containing monomer is from the viewpoint of increasing the glossiness value of the protective film formed of the film for forming a protective film, and the wafer with the protective film produced by using the composite sheet. The total structural unit (100% by mass) of the (A1) acrylic polymer is preferably from 1 to 30% by mass, more preferably from 5 to 27% by mass, particularly preferably from the viewpoint of good reliability. 10~24% by mass.

The content of the constituent unit (a2) is preferably from 1 to 50% by mass, more preferably from 5 to 45% by mass, even more preferably from 10 to 40%, based on the total structural unit (100% by mass) of the (A1) acrylic polymer. The mass% is more preferably 20 to 40% by mass.

(composed from other monomers)

Further, the acrylic polymer (A1) may have a constituent unit (a3) derived from another monomer other than the above constituent units (a1) and (a2), within a range not impairing the effects of the present invention.

Examples of the other monomer include vinyl acetate, styrene, ethylene, and an α-olefin.

The total content of the constituent units (a3) derived from the other monomers is preferably 0 to 20% by mass, more preferably 0 to 15% based on the total constituent unit (100% by mass) of the (A1) acrylic polymer. The mass% is particularly preferably 0 to 10% by mass, and more preferably 0 to 2% by mass.

((A2) non-acrylic resin)

The film for forming a protective film used in the present invention may further contain (A2) a non-acrylic resin as a resin component other than the above (A1) acrylic polymer, as needed.

Examples of the (A2) non-acrylic resin include polyester, phenoxy resin, polycarbonate, polyether, polyurethane, polyoxyalkylene, and rubber-based polymer.

These resins may be used alone or in combination of two or more.

The weight average molecular weight of the non-acrylic resin (A2) is preferably 20,000 or more, more preferably 20,000 to 100,000, and particularly preferably 20,000 to 80,000.

(A2) The non-acrylic resin may be used alone. However, by using the above-mentioned (A1) acrylic polymer in combination, the interlayer peeling of the adhesive sheet and the protective film forming film can be easily performed, and the occurrence of voids or the like can be suppressed.

When the (A2) non-acrylic resin and the above (A1) acrylic polymer are used in combination, the mass ratio of (A2) non-acrylic resin to (A1) acrylic polymer [(A2)/(A1)], from the above From the viewpoint, it is preferably 1/99 to 60/40, more preferably 1/99 to 30/70.

Further, in the constituent unit of the (A1) acrylic polymer, the (A1) acrylic polymer or the epoxy group-containing phenoxy resin is used when the constituent unit of the epoxy group-containing monomer is contained. It has thermosetting properties, but these are not (B) hardenable components, but are included in the concept of (A) polymer components.

[(B) hardenable ingredients]

(B) The curable component is a compound which hardens a film for forming a protective film to form a hard protective film, and has a weight average molecular weight of less than 20,000.

The film for forming a protective film to be used in the present invention preferably contains at least one of a thermosetting component (B1) and an energy ray-curable component (B2) as a (B) curable component, and suppresses formation of a protective film. From the viewpoint of the coloring of the protective film formed by the film, and the viewpoint of cost reduction, it is more preferable to contain at least the thermosetting component (B1).

The thermosetting component (B1) preferably contains a compound having a functional group which is at least reacted by heating.

Further, the energy ray-curable component (B2) contains a compound (B21) having a functional group which is reacted by irradiation with an energy ray, and is polymerized and cured by irradiation with an ultraviolet ray or an energy ray of an electron beam.

The functional groups of these hardenable components are hardened by reacting each other to form a three-dimensional network structure.

(B) The weight average molecular weight (Mw) of the curable component is preferably used in combination with the component (A) to suppress the viscosity of the composition for forming the film for forming a protective film, thereby improving workability and the like. It is less than 20,000, more preferably 10,000 or less, and particularly preferably 100 to 10,000.

(thermosetting component (B1))

The thermosetting component (B1) is preferably an epoxy thermosetting component.

The epoxy-based thermosetting component is preferably a compound (B11) having an epoxy group and a thermosetting agent (B12).

Examples of the epoxy group-containing compound (B11) (hereinafter also referred to as "epoxy compound (B11)") include a polyfunctional epoxy resin, bisphenol A diglycidyl ether, and a hydrogenated product thereof. O-cresol novolac epoxy resin, dicyclopentadiene epoxy resin, biphenyl epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin, phenyl skeleton epoxy resin An epoxy compound or the like having two or more functional groups in the molecule.

These epoxy compounds (B11) may be used alone or in combination of two or more.

The content of the epoxy compound (B11) is preferably from 1 to 500 parts by mass, more preferably from 3 to 300 parts by mass, even more preferably from 10 to 150 parts by mass, even more preferably 100 parts by mass of the component (A). 20 to 120 parts by mass.

(thermal hardener (B12))

The heat hardener (B12) is a function of a hardener for the epoxy compound (B11).

The thermosetting agent is preferably a compound having two or more functional groups capable of reacting with an epoxy group in one molecule.

Examples of the functional group include a phenolic hydroxyl group, an alcoholic hydroxyl group, an amine group, a carboxyl group, and an acid anhydride. Among these, a phenolic hydroxyl group, an amine group or an acid anhydride is preferred, and a phenolic hydroxyl group or an amine group is more preferred, and an amine group is particularly preferred.

Examples of the phenolic thermosetting agent having a phenol group include a polyfunctional phenol resin, a biphenol, a novolak type phenol resin, a dicyclopentadiene type phenol resin, a xylok type phenol resin, and a phenol resin. Alkyl phenol resin and the like.

Examples of the amine-based thermosetting agent having an amine group include dicyandiamide (DICY) and the like.

These heat hardeners (B12) can be used individually or in combination of 2 or more types.

The content of the thermosetting agent (B12) is preferably from 0.1 to 500 parts by mass, more preferably from 1 to 200 parts by mass, per 100 parts by mass of the epoxy compound (B11).

(hardening accelerator (B13))

In order to adjust the heat hardening rate of the film for forming a protective film, a hardening accelerator (B13) can be used. The hardening accelerator (B13) is preferably used in combination with the epoxy compound (B11) as the thermosetting component (B1).

Examples of the curing accelerator (B13) include tertiary derivatives such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol. Amines; 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl -5-hydroxymethylimidazole and the like imidazoles; tributylphosphine, An organic phosphine such as diphenylphosphine or triphenylphosphine; a tetraphenylboron salt such as tetraphenylphosphonium tetraphenylborate or triphenylphosphine tetraphenylborate; and the like.

These hardening accelerators (B13) can be used individually or in combination of 2 or more types.

The content of the curing accelerator (B13) is improved from the viewpoint of improving the adhesion of the protective film formed of the film for forming a protective film and improving the reliability of the wafer with the protective film produced by using the composite sheet. The total amount of 100 parts by mass of the epoxy compound (B11) and the thermosetting agent (B12) is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 6 parts by mass, still more preferably 0.3 to 4 parts by mass.

(energy line hardening component (B2))

As the energy ray-curable component (B2), a compound (B21) having a functional group which is reacted by irradiation with an energy ray can be used alone, but it is preferred to use a photopolymerization initiator (B22) in combination with the compound (B21). .

(Compound (B21) having a functional group reactive by irradiation with an energy ray)

The compound (B21) having a functional group which is reacted by the irradiation of the energy ray (hereinafter also referred to as "energy ray-reactive compound (B21)") may, for example, be trimethylolpropane triacrylate or pentaerythritol triacrylate. Pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, oligoester acrylate, amine group A An acid ester acrylate oligomer, an epoxy acrylate, a polyether acrylate, an itaconic acid oligomer, or the like.

These energy ray-reactive compounds (B21) may be used alone or in combination of two or more.

Further, the mass average molecular weight (Mw) of the energy ray-reactive compound (B21) is preferably from 100 to 30,000, more preferably from 300 to 10,000.

The content of the energy ray-reactive compound (B21) is preferably from 1 to 1,500 parts by mass, more preferably from 3 to 1200 parts by mass, per 100 parts by mass of the component (A).

(Photopolymerization initiator (B22))

By using the photopolymerization initiator (B22) in combination with the above-mentioned energy ray-reactive compound (B22), the polymerization hardening time can be shortened, and even if the amount of light irradiation is reduced, the film for forming a protective film can be cured.

The photopolymerization initiator (B22) is exemplified above.

The content of the photopolymerization initiator (B22) is more than 100 parts by mass of the energy ray-reactive compound (B21) from the viewpoint of suppressing the formation of the residue by the curing reaction of the film for forming a protective film. Preferably, it is 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass.

The content of the component (B) is preferably from 5 to 50% by mass, more preferably from 8 to 40% by mass, even more preferably from 10 to 30% by mass, based on the total amount (100% by mass) of the composition for forming a protective film. More preferably, it is 12 to 25% by mass.

Further, the content of the component (B) is a thermosetting component (B1) containing the epoxy compound (B11), a thermosetting agent (B12), and a curing accelerator (B13), and an energy ray-reactive compound (B21). And the total content of the energy ray hardening component (B2) of the photoinitiator (B22).

[(C) colorant]

In the film for forming a protective film, it is preferred to further contain (C) a colorant.

When a semiconductor wafer having a protective film formed of a film for forming a protective film is placed in a device by containing a coloring agent (C) in the film for forming a protective film, infrared rays generated by the surrounding device can be shielded. Prevent malfunction of the semiconductor wafer.

As the (C) colorant, organic or inorganic pigments and dyes can be used.

As the dye, for example, any one of an acid dye, a reactive dye, a direct dye, a disperse dye, a cationic dye, and the like can be used.

Further, the pigment is not particularly limited, and can be appropriately selected from known pigments.

Among these, a black pigment is preferred from the viewpoint of good shielding properties by electromagnetic waves or infrared rays and further improving the visibility of the laser marking method.

Examples of the black pigment include carbon black, iron oxide, manganese dioxide, aniline black, and activated carbon. From the viewpoint of improving the reliability of the semiconductor wafer, carbon black is preferred.

In addition, these (C) coloring agents can be used individually or in combination of 2 or more types.

The content of the component (C) is preferably 0.1 to 30% by mass, more preferably 0.5 to 25% by mass, even more preferably 1.0 to 15% by mass, even more preferably the total amount (100% by mass) of the film for forming a protective film. Good is 1.2~5 mass%.

[(D) coupling agent]

In the film for forming a protective film, it is preferred to further contain (D) a coupling agent.

By containing the (D) coupling agent, the (A) polymer component and the surface of the semiconductor wafer or the surface of the filler in the film for protective film formation can be bonded to improve adhesion or cohesiveness. Moreover, the water resistance can be improved without impairing the heat resistance of the protective film formed of the film for forming a protective film.

The (D) coupling agent is preferably a compound which reacts with a functional group of the component (A) or the component (B), and more preferably a decane coupling agent.

Examples of the decane coupling agent include γ-glycidoxypropyltrimethoxydecane, γ-glycidoxypropylmethyldiethoxydecane, and β-(3,4-epoxy group. Cyclohexyl)ethyltrimethoxydecane, γ-(methacryloxypropyl)trimethoxydecane, γ-aminopropyltrimethoxydecane, N-6-(aminoethyl)-γ -Aminopropyltrimethoxydecane, N-6-(aminoethyl)-γ-aminopropylmethyldiethoxydecane, N-phenyl-γ-aminopropyltrimethoxydecane , γ-ureidopropyltriethoxydecane, γ-mercaptopropyltrimethoxydecane, γ-mercaptopropylmethyldimethoxydecane, bis(3-triethoxydecylpropyl)tetra Sultan, methyltrimethoxydecane, methyltriethoxydecane, vinyltrimethoxydecane, vinyltriethoxydecane, imidazolium, and the like.

These (D) coupling agents may be used alone or in combination of two or more.

As the (D) coupling agent, an oligomer type coupling agent is preferred.

The molecular weight of the (D) coupling agent which also contains the oligomer-type coupling agent is preferably from 100 to 15,000, more preferably from 150 to 10,000, still more preferably from 200 to 5,000, still more preferably from 250 to 3,000, and even more preferably. It is 350~2000.

The content of the component (D) is preferably 0.01 to 10% by mass, more preferably 0.05 to 7% by mass, even more preferably 0.10 to 4% by mass, even more preferably the total amount (100% by mass) of the film for forming a protective film. Good is 0.15~2% by mass.

[(E) Inorganic filler]

In the film for forming a protective film, it is preferred to further contain (E) an inorganic filler.

By including the (E) inorganic filler, the thermal expansion coefficient of the protective film formed of the film for forming a protective film can be adjusted to an appropriate range, and the thermal expansion coefficient of the wafer with the protective film can be optimized, so that the assembly can be improved. The reliability of the semiconductor device of the wafer. Further, the moisture absorption rate of the protective film formed of the film for forming a protective film can be reduced.

Examples of the (E) inorganic filler include powders of vermiculite, alumina, talc, calcium carbonate, titanium oxide, iron oxide, tantalum carbide, boron nitride, and the like, such spheroidized beads and single crystal fibers. And glass fiber and so on.

These (E) inorganic fillers can be used alone or in combination of two or more.

Among these, vermiculite or alumina is preferred.

The average particle diameter of the (E) inorganic filler is preferably from 0.3 to 50 μm, more preferably from 0.5 to 30 μm, even more preferably from 0.7 to 10 μm, from the viewpoint of improving the gloss value of the formed protective film.

Further, in the present invention, the average particle diameter of the (E) inorganic filler refers to a value measured by a laser diffraction scattering type particle size distribution measuring apparatus.

The content of the component (E) is preferably from 25 to 80% by mass, more preferably from 30 to 70% by mass, even more preferably from 40 to 65% by mass, even more preferably the total amount (100% by mass) of the film for forming a protective film. Good is 45~60% by mass.

[(F) Universal Additives]

In addition to the above, in the film for forming a protective film, various additives may be blended as needed.

Examples of the various additives include a crosslinking agent, a leveling agent, a plasticizer, an antistatic agent, an antioxidant, an ion scavenger, a getter, and a chain transfer agent.

The content of each of the components (F) is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, even more preferably 0 to 5 by mass based on the total amount (100% by mass) of the film for forming a protective film. %, more preferably 0 to 2% by mass.

<Method for Producing Film for Forming Protective Film>

The method for producing the film for forming a protective film is not particularly limited, and it can be produced by a known method. For example, an organic solvent may be added to the raw material composition containing the above components to form a solution of the raw material composition, and the solution may be applied onto the release sheet by a known coating method to form a coating film. It is dried and formed on the release sheet to form a film for forming a protective film.

Examples of the organic solvent to be used include toluene, ethyl acetate, and methyl ethyl ketone.

The solid content concentration of the solution of the protective film-forming composition in the case of blending the organic solvent is preferably from 10 to 80% by mass, more preferably from 20 to 70% by mass, even more preferably from 30 to 65% by mass.

Examples of the coating method include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method.

The film for forming a protective film of the composite sheet of the present invention may be a single layer or a multilayer structure of two or more types.

The thickness of the film for forming a protective film is not particularly limited, but is preferably 3 to 300 μm, more preferably 5 to 250 μm, and particularly preferably 7 to 200 μm. When the film for forming a protective film has a multilayer structure, the total thickness is Jia is also in the range.

[Physical properties and use of composite sheets for forming protective film]

The composite sheet of the present invention can be produced by laminating an adhesive layer of the above-mentioned pressure-sensitive adhesive sheet and a film for forming a protective film.

The film for forming a protective film of the composite sheet of the present invention is a protective film which can be adhered by curing. The film for forming a protective film is attached to the back surface of a workpiece such as a wafer-oriented semiconductor wafer or a semiconductor wafer, and is cured by an appropriate means to serve as a sealing resin instead of a workpiece such as a semiconductor wafer or a semiconductor wafer. The function of the back. For example, when attached to a semiconductor wafer, since the protective film has a function of reinforcing the wafer, damage of the wafer or the like can be prevented.

Further, the composite sheet of the present invention can be used as a sheet for fixing a workpiece such as a semiconductor wafer during blade cutting, and it is not necessary to separately bond the dicing sheet for dicing, and the process of the semiconductor device can be simplified.

In addition, the composite sheet of the present invention can also be used in a so-called pre-cut method (on a semiconductor wafer, from the side of the circuit surface, a trench deeper than the thickness of the desired wafer is formed, from the back side of the semiconductor wafer The thinning process is performed until at least the groove is reached, and the method of obtaining the wafer group can be attached to the singulated wafer group for use.

In the composite sheet for forming a protective film of the present invention, after the film for forming a protective film which is provided in the composite sheet for forming a protective film is attached to a workpiece, the adhesive sheet of the composite sheet for forming a protective film is not peeled off. The glossiness value of the protective film obtained by hardening the film for forming a protective film at a temperature of 130 ° C for 2 hours showed a high value.

The gloss value of the protective film is preferably 40 or more, more preferably 44 or more.

[wafer with protective film]

The wafer with a protective film of the present invention has a protective film obtained by attaching a composite sheet of the present invention to a back surface of a wafer such as a semiconductor wafer, and curing the film for forming a protective film of the composite sheet.

Further, the protective film of the wafer with a protective film of the present invention may be completely cured, or may be partially cured, but is preferably completely cured.

In the protective film of the wafer with a protective film of the present invention, the gloss value of the protective film measured from the side opposite to the side of the wafer is preferably 40 or more, and more preferably 44 or more. When the gloss value is 40 or more, it is possible to provide a wafer with a protective film excellent in laser mark adaptability.

Further, the gloss value of the protective film of the wafer with the protective film can be subjected to a curing treatment to form a protective film, and the workpiece is attached using a protective film before cutting, as will be described later.

The gloss value of the protective film of the wafer with the protective film measured on the side opposite to the wafer side, and the gloss value of the protective film of the wafer with the protective film measured on the side opposite to the side of the workpiece I think the system is roughly the same.

A wafer with a protective film can be fabricated by mounting it on a substrate or the like in a face-down manner. Further, the wafer with the protective film may be fabricated by following the die pad portion or another member such as a semiconductor wafer (on the wafer mounting portion).

[Method of Manufacturing Wafer with Protective Film]

The method for producing a wafer with a protective film of the present invention is not particularly limited, but for example, the following method of blade cutting having the following steps (1) to (4) is preferred, and step (1): on the back side of the workpiece a step of attaching the composite sheet for forming a protective film of the present invention; a step (2): a step of cutting the workpiece; and a step (3): removing the adhesive sheet of the composite sheet for forming a protective film, thereby forming a protective film The step of forming a protective film by hardening the film; and the step (4): picking up the workpiece with the cut protective film obtained by the steps (1) to (3) to obtain a wafer with a protective film.

Further, in the method for producing a wafer with a protective film according to the present invention, the order of steps (1), (2), (3), and (4) may be performed without being in the order of steps (2) and (3). It is also possible to manufacture a wafer with a protective film in the order of steps (1), (3), (2), and (4).

<Step (1)>

In the step (1), a step of attaching a film for forming a protective film of the composite sheet of the present invention to a back surface of a workpiece such as a semiconductor wafer to obtain a film having a film for forming a protective film.

Here, the semiconductor wafer may be a germanium wafer, and may also be a compound semiconductor wafer such as gallium/arsenic. Further, the semiconductor wafer may have a circuit formed on the surface thereof, and the back surface may be appropriately ground or the like to have a thickness of about 50 to 500 μm.

<Step (2)>

In the step (2), the workpiece selected from the workpiece with the film for forming a protective film and the workpiece with the protective film is cut and processed into a wafer in accordance with each circuit formed on the surface of the workpiece.

In addition, the workpiece to be cut in the step may be a workpiece having a film for forming a protective film obtained in the step (1), or may be subjected to the step (3) after the step (1). A workpiece with a protective film.

Moreover, the cutting of the workpiece can be carried out by a well-known method.

In the present step, the adhesive sheet of the present invention is excellent in adhesion between the adhesive layer and the protective film forming film or the protective film, and can effectively suppress the phenomenon that the cutting water penetrates between the adhesive layer and the protective film forming film or the protective film. . Therefore, according to the method for producing a wafer with a protective film of the present invention, it is possible to manufacture a wafer with a protective film which is not contaminated by cutting water while improving productivity.

Here, after the step (1), the workpiece having the cut film for forming a protective film is obtained through this step, and in the next step (3), the film for forming a protective film is cured to obtain a cut film. A workpiece with a protective film.

On the other hand, after the step (1), when the step (3) is passed, in this step, the workpiece with the protective film obtained in the step (3) is cut to obtain a workpiece with the cut protective film.

<Step (3)>

In the step (3), the adhesive sheet having the protective film forming composite sheet is not peeled off, and the protective film forming film is cured to form a protective film.

The adhesive layer of the adhesive sheet of the composite film for forming a protective film attached to the workpiece maintains low fluidity during heating.

Therefore, in the production method of the present invention, since the adhesive sheet for forming a protective film is not peeled off, the film for forming a protective film is cured, so that the surface of the adhesive layer of the adhesive sheet is maintained even if heated. The smoothness can form a protective film having a gloss value of 40 or more.

The curing of the film for forming a protective film can be carried out by any of the types of the curable component contained in the film for forming a protective film by heat hardening and irradiation with an energy ray. The viewpoint of the coloration of the formed protective film is preferably at least thermally cured from the viewpoint of sufficiently proceeding the curing reaction and from the viewpoint of cost reduction.

As a condition for performing thermal curing, the curing temperature is preferably from 100 to 150 ° C, and the curing time is preferably from 1 to 3 hours.

Moreover, the conditions at the time of hardening by irradiation of an energy ray can be suitably set according to the kind of the energy line used. For example, when ultraviolet rays are used, the illuminance is preferably from 170 to 250 mW/cm ² , and the amount of light is preferably from 600 to 1000 mJ/cm ² .

<Step (4)>

In the step (4), the workpiece having the protective film obtained by the steps (1) to (3) is picked up by a general means such as a collet to obtain a wafer with a protective film.

By this step, a semiconductor wafer (a wafer with a protective film) having a protective film on the back side which is singulated is obtained.

Further, in the conventional production method, after the protective film is formed by thermal curing, the picking up step of this step tends to be difficult to pick up.

With respect to the method for producing a wafer with a protective film of the present invention, an adhesive layer having an adhesive composition containing a specific energy ray-curable acrylic copolymer is used, and the adhesive layer is used. The composite sheet of the present invention having the hardened region therein has good pick-up property and can improve the productivity of the wafer with the protective film.

The protective film-coated wafer obtained by the production method of the present invention has a high gloss value of the protective film and is excellent in laser mark adaptability, and can be used as a protective film excellent in visibility of a laser printed portion on the surface of the protective film. Wafer.

The gloss value of the protective film measured on the opposite side to the wafer side of the wafer with the protective film obtained by the production method of the present invention is preferably 40 or more, more preferably 44 or more.

[Examples]

In the following description, the weight average molecular weight (Mw) and the glass transition temperature (Tg) of each component are values measured or calculated by the methods described below.

<weight average molecular weight (Mw)>

Using a gel permeation chromatography apparatus (product name "HLC-8220GPC" manufactured by Tosoh Co., Ltd.), the measurement was carried out under the following conditions, and the values measured in terms of standard polystyrene were used.

(measurement conditions)

. Pipe column: "TSK guard column HXL-H" "TSK gel GMHXL (×2)" "TSK gel G2000HXL" (both manufactured by Tosoh Co., Ltd.)

. Column temperature: 40 ° C

. Developing solvent: tetrahydrofuran

. Flow rate: 1.0mL/min

<glass transition temperature (Tg)>

The value calculated by the above formula (1) is used.

Production Example 1 (Production of Film for Forming Protective Film) (1) Modification of a solution of a raw material composition of a film for forming a protective film

The following components (A) to (F) were added to the blending amounts shown below, and diluted with methyl ethyl ketone to prepare a solution of a raw material composition of a film for forming a protective film having a solid concentration of 61% by mass.

<(A) Polymer component>

. Acrylic copolymer composed of n-butyl acrylate (BA), methyl methacrylate (MMA), glycidyl methacrylate (GMA) and 2-hydroxyethyl acrylate (HEA) (BA/MMA/GMA /HEA=55/10/20/15 (% by mass), Mw: 900,000, Tg: -28 ° C): 100 parts by mass (solid content ratio).

<(B) hardenable component>

. Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name "jER828", epoxy equivalent: 180 to 200, molecular weight: 370, equivalent to the compound of the above (B11) component): 50 parts by mass (solid content) ratio).

. Dicyclopentadiene type epoxy resin (manufactured by Dainippon Ink Chemical Industry Co., Ltd., trade name "Epiclon HP-7200HH", compound having a weight average molecular weight of less than 20,000, and compound of the above (B11) component): 50 Parts by mass (solid content ratio).

. Dicyanamide (manufactured by ADEKA Co., Ltd., trade name "Adeka Hardener 3636AS", amine-based curing agent, a compound corresponding to the above (B12) component): 2.8 parts by mass (solid content ratio).

. 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Chemicals Co., Ltd., trade name "Curezol 2PHZ", hardening accelerator, compound corresponding to the above (B13) component): 2.8 parts by mass (solid content) ratio).

<(C) colorant>

. Carbon black: 10 parts by mass (solid content ratio).

<(D) decane coupling agent>

. A-1110 (trade name, manufactured by Japan UNICAR Co., Ltd.): 1 part by mass (solid content ratio).

<(E) Inorganic filler>

. Molten vermiculite (average particle diameter: 8 μm): 300 parts by mass (solid content ratio).

(2) Production of a film for forming a protective film

A solution of the prepared raw material composition was applied to a release-treated surface of a release sheet (manufactured by LINTEC Co., Ltd., trade name "SP-PET3811", thickness: 38 μm), and the thickness was 25 μm, and the solution was applied at 120 ° C. A film for forming a protective film was formed on the release sheet by a drying treatment for 2 minutes.

Then, on the film for forming a protective film formed on the film, a release-treated surface of another release sheet (trade name "SP-PET381031", thickness: 38 μm, manufactured by LINTEC Co., Ltd.) was bonded to each other to form a release sheet of two sheets. A film for forming a protective film having a thickness of 25 μm.

Examples 1 to 5 and Comparative Examples 1 to 6 (1) Modulation of the solution of the adhesive composition

Each component of the type and the blending amount shown in Table 2 was added, and diluted with ethyl acetate to prepare a solution of the adhesive composition having a solid concentration of 24% by mass. The details of each component are as follows.

<acrylic copolymer>

The acrylic copolymers A1 to A10 obtained as follows were used: for the acrylic polymer of the raw material monomers of the types and ratios shown in Table 1, the methacrylic acid methacrylate was added in the amount shown in Table 1. The ester was synthesized by reacting dibutyltin laurate as a catalyst under an ethyl acetate solution at 25 ° C under normal pressure for 24 hours.

Further, the glass transition temperature of the Tg-based acrylic polymer in Table 1 and Mw represent the weight average molecular weight of the acrylic copolymer obtained by reacting with methacrylic acid methoxyethyl acrylate. Further, the acrylic copolymers A1 to A9 are energy ray-curable acrylic copolymers having a methacryl fluorenyl group.

<Photopolymerization initiator>

. Irgacure 184: trade name ("Irgacure" is a registered trademark), manufactured by BASF Corporation, 1-hydroxycyclohexyl phenyl ketone.

<crosslinker>

. BHS-8515: trade name, toluene diisocyanate compound, manufactured by Toyo Ink Manufacturing Co., Ltd.

<Polymerizable composition>

. UV-5806: a polymerizable product of a 10-functional urethane acrylate (Mw: 1740) and a photopolymerization initiator, manufactured by Nippon Synthetic Chemical Co., Ltd.

(2) Making of adhesive sheets

A solution of the prepared adhesive composition was applied to a release-treated surface of a release sheet (manufactured by LINTEC Co., Ltd., trade name "SP-PET3811", thickness: 38 μm) so that the coating amount after drying was 10 g/m ² . After drying at 100 ° C for 1 minute, an adhesive layer was formed on the release sheet, and a polypropylene film (manufactured by Mitsubishi Resin Co., Ltd., trade name "CT265") having a thickness of 100 μm was laminated on the adhesive layer. .

Then, in Examples 1 to 5 and Comparative Examples 1 to 5, an ultraviolet irradiation device (product name "RAD-2000 m/12" manufactured by LINTEC Co., Ltd., irradiated with ultraviolet rays (illuminance 140 mW/cm ² , light amount 510 mJ) was used from the side of the release sheet. /cm ² ), the adhesive layer is fully cured to form an adhesive sheet having an adhesive layer containing a hardened region.

On the other hand, in Comparative Example 6, an adhesive sheet having an adhesive layer containing no hardened region was produced in the same manner as in Example 1 except that the above-described ultraviolet irradiation was not performed.

(3) Production of composite sheet for forming a protective film

On the hardened region of the adhesive layer from which the release sheet of the adhesive sheet was removed to expose the surface of the adhesive sheet, the peeling of one side of the film for forming a protective film sandwiched between the two release sheets produced in Production Example 1 was directly laminated. After the sheet is removed to expose the film for forming a protective film on the surface, the remaining release sheet is also removed, and the film for forming a protective film is exposed on the surface.

Then, on the surface of the film for forming a protective film on the exposed surface, a double-sided adhesive tape (manufactured by LINTEC Co., Ltd., manufactured by LINTEC Co., Ltd.) having a release sheet on both sides of a member for forming a post-attach layer attached to the ring frame portion is provided. Adwill G-01DF"), the release sheet of one side of the double-sided adhesive sheet sampled into a circular shape of 245 mm in diameter was removed, and the adhesive layer of the double-sided adhesive sheet and the protective film forming layer were laminated. Next, the outer diameter (diameter 270 mm) of the adhesive portion conforming to the ring frame is made, and the removed circle with the double-sided adhesive tape is made. The portion in which the shape is formed into a concentric circle is molded into a circular shape to produce a composite sheet for forming a protective film having the structure shown in Fig. 2(b).

The composite sheet for forming a protective film produced as described above was evaluated by the following method. The evaluation results are shown in Table 2.

(1) Whether the cutting water is infiltrated during cutting

Using an adhesive sheet attaching device (manufactured by LINTEC Co., Ltd., product name "Adwill RAD2700"), the surface of the tantalum wafer which has been subjected to #2000 polishing with a thickness of 200 μm and a diameter of 8 Å is attached to a temperature of 70 ° C. The film for forming a protective film of the composite sheet for forming a protective film produced in the examples and the comparative examples. Also, the ring frame is attached at the same time.

Then, the wafer to which the composite sheet for protective film formation was attached was placed in an oven heated to 130 ° C for 2 hours to cure the film for forming a protective film to form a protective film.

Then, using a cutter (manufactured by DISCO, product name "DFD651"), a groove of a depth of 15 μm was introduced into the base material of the composite sheet for forming a protective film at a blade speed of 40 mm/sec to cut the wafer. It became a wafer of 3 mm × 3 mm size.

Thereafter, the cut water was visually observed between the infiltration of the protective film and the adhesive layer.

Table 2 shows the number of wafers in which the cutting water was infiltrated due to insufficient adhesion to the wafer after the above operations were performed on 30 wafers.

(2) Picking adaptability

The 3mm × 3mm wafer fabricated in the above evaluation of "(1) There is no water infiltration during cutting" is used as the cut wafer. After the expansion of the sample was carried out by a draw of 3 mm, a wafer bonding machine (product name "Bestem-D02" manufactured by Canon Machinery Co., Ltd.) was used to pick up 50 wafers.

In addition, in the sample of the 3 mm × 3 mm wafer which was produced by the above-mentioned "(1) There is no water infiltration at the time of cutting", the ultraviolet irradiation device (manufactured by LINTEC Co., Ltd.) was used. product name "RAD-2000m / 12 ', after irradiated with ultraviolet rays (illuminance of 220mW / cm ^2, light quantity of 190mJ / cm ^2), using the wafer bonding machine, picked up 50 of the wafer.

Table 2 shows the number of pickables for 50 wafers.

(3) Gloss value

Using an adhesive sheet attaching device (manufactured by LINTEC Co., Ltd., product name "Adwill RAD2700"), the surface of the tantalum wafer (200 mm in diameter and 280 μm in thickness) which had been subjected to #2000 polishing was attached while being heated to 70 °C. The film for forming a protective film of the composite sheet for forming a protective film produced in the examples and the comparative examples.

Then, the wafer to which the composite sheet for protective film formation was attached was placed in an oven heated to 130 ° C for 2 hours to cure the film for forming a protective film to form a protective film.

Further, only 6 In Comparative Examples, after forming the protective film, an ultraviolet irradiation device (of LINTEC Corporation, product name "RAD-2000m / 12", irradiated with ultraviolet rays (illuminance 220mW / cm ^2, light quantity of 190mJ / cm ²⁾ .

Next, the adhesive sheet on the formed protective film was removed to prepare a test sample.

Then, using a gloss meter (product name "VG2000" manufactured by Nippon Denshoku Industries Co., Ltd.), according to JIS Z 8741, the surface of the test film was measured at 60 degrees from the side opposite to the side of the test wafer. Specular gloss, the measured value is taken as the gloss value of the protective film.

(4) Laser marking adaptability

Using an adhesive sheet attaching device (manufactured by LINTEC Co., Ltd., product name "Adwill RAD2700"), the surface of the tantalum wafer which has been subjected to #2000 polishing with a thickness of 200 μm and a diameter of 8 Å is attached to a temperature of 70 ° C. The film for forming a protective film of the composite sheet for forming a protective film produced in the examples and the comparative examples. Also, the ring frame is attached at the same time.

Then, the wafer to which the composite sheet for protective film formation was attached was placed in an oven heated to 130 ° C for 2 hours to cure the film for forming a protective film to form a protective film.

Next, using a laser marking machine (Hitachi Construction Machinery Precision Technology Co., Ltd., product name "YAG Laser Marking Machine LM5000"), on the substrate side of the adhesive sheet, printing text of 400 μm in length and 200 μm in width on the protective film. .

In the comparative example 6, the wafer to which the composite film for forming a protective film was attached was irradiated with ultraviolet rays (illuminance of 220 mW/cm, manufactured by LINTEC Co., Ltd., product name "RAD-2000m/12"). ² , the amount of light is 190mJ/cm ² ).

Then, after the adhesive sheet of the composite sheet for forming a protective film was removed, the characters printed on the protective film were visually observed and evaluated by the following criteria.

A: The text is clear.

F: The text is not clear.

In the composite sheet for forming a protective film of Examples 1 to 5, no cutting water was observed to penetrate between the protective film and the adhesive layer at the time of cutting, and the pick-up property was also good. In addition, the protective film formed of the composite sheet for forming a protective film has a high gloss value and excellent laser marking suitability.

On the other hand, the composite sheets for forming protective films of Comparative Examples 1, 2, 5, and 6 exhibited poor pickup adaptability. Further, in comparison with the examples, the protective film formed by the composite sheet for forming a protective film has a low gloss value and poor laser mark adaptability.

Further, in Comparative Examples 3 and 4, it was observed that the cutting water penetrated between the protective film and the adhesive layer at the time of cutting. In particular, in Comparative Example 4, since the wafer in which the cutting water was not immersed could not be produced, the evaluation of the pick-up adaptability, the gloss value, and the laser mark adaptability could not be completed, and the evaluation was terminated without performing such evaluation.

Industrial utilization possibility

The composite sheet for forming a protective film of the present invention is suitable as a protective film forming material for protecting the back surface of a semiconductor wafer.

Claims (13)

A composite sheet for forming a protective film, comprising a composite sheet for forming a protective film for forming an adhesive sheet and a film for forming a protective film, the adhesive sheet having a substrate and an adhesive layer and containing a hardened region in the adhesive layer, the protection The film for film formation is directly laminated on a hardened region in the adhesive layer; the adhesive layer is a layer formed of an adhesive composition containing an energy ray-curable acrylic copolymer, the energy ray-curable acrylic copolymer The energy-polymerizable group is introduced into the acrylic polymer (X) containing the structural unit (x1) derived from vinyl acetate. The composite sheet for forming a protective film according to claim 1, wherein the content of the constituent unit (x1) derived from vinyl acetate is from 10 to 75% by mass based on the total constituent unit of the acrylic polymer (X). The composite sheet for forming a protective film according to claim 1 or 2, wherein the energy ray polymerizable group is a (meth) acrylonitrile group. The composite sheet for forming a protective film according to claim 1 or 2, wherein the energy ray-curable acrylic copolymer contains a constituent unit (x1) derived from vinyl acetate and a constituent unit (x2) derived from a monomer having a functional group. The acrylic polymer (X) and an acrylic copolymer obtained by reacting a polymerizable compound (Y) having an energy ray-polymerizable group. The composite sheet for forming a protective film according to claim 4, wherein the value of α calculated by the following formula (2) is 20 or less; and the formula (2): α = [P] × [Q] × [R] / 100 In the formula (2), [P] represents a monomer derived from a functional group with respect to 100% by mass of the total constituent unit of the acrylic polymer (X). The content ratio of the structural unit (x2); [Q] represents the equivalent of the polymerizable compound (Y) with respect to 100 equivalents of the functional group of the functional group-containing monomer which the acrylic polymer (X) has ; [R] represents the base of the energy ray polymerizable group of the polymerizable compound (Y). The composite sheet for forming a protective film according to claim 1 or 2, wherein the film for forming a protective film contains (A) a polymer component and (B) a curable component. The composite sheet for forming a protective film according to claim 6, wherein the film for forming a protective film contains a thermosetting component (B1) as a (B) curable component. The composite sheet for forming a protective film according to claim 7, wherein the protective film forming film of the protective film forming film is attached to the workpiece, and the adhesive layer of the protective film forming composite sheet is not peeled off. In the sheet, the protective film obtained by curing the film for forming a protective film at a temperature of 130 ° C for 2 hours had a gloss value of 40 or more. The composite sheet for forming a protective film according to claim 1 or 2, wherein the substrate is a substrate containing a polypropylene film. A protective film-forming wafer having a protective film formed by curing a film for forming a protective film of the composite sheet for forming a protective film according to any one of claims 1 to 9 on the back surface of the wafer. The wafer of the protective film of claim 10, wherein the protective film has a gloss value of 40 or more as measured from the side opposite to the side having the wafer. A method for producing a wafer with a protective film, comprising the following steps (1) to (4): step (1): attaching a composite film for forming a protective film according to any one of claims 1 to 9 on the back surface of the workpiece Step of filming; Step (2): a step of cutting the workpiece; and (3): a step of curing the film for forming a protective film to form a protective film without peeling off the adhesive sheet of the composite sheet for forming a protective film; : a step of picking up the processed film with the protective film obtained by the steps (1) to (3) to obtain a wafer with a protective film. A protective film-containing wafer which is obtained by the manufacturing method of claim 12, wherein the protective film is protected from the side opposite to the side having the wafer. The film has a gloss value of 40 or more.