TWI595067B - Surface protection sheet - Google Patents

Description

Surface protection sheet

The present invention relates to a surface protection sheet suitable for the grinding step of a work.

In recent years, with the integration of electronic devices, thinning and miniaturization of semiconductor wafers are urgently required. When an extremely thin semiconductor wafer is obtained and is to be mounted on a device, there is a method of thinning a workpiece by polishing a semiconductor wafer or the like before being divided into wafers. However, in this case, there is a risk of (1) damage to the thinned workpiece during work, or (2) risk of breakage of the wafer after the workpiece is divided into wafers.

As a method of dividing a workpiece into wafers by avoiding the risk of the above (1), a workpiece division method called "pre-dicing method" is conventionally known. The "pre-cut method" is a method in which a groove is formed on the surface side of the workpiece along the dividing line, and the wafer is divided into wafers by thinning the workpiece or the like from the back side of the workpiece to at least the groove.

For example, in Patent Document 1, a groove is formed along a predetermined boundary line between the pellets on the surface side of the ruthenium substrate, and a resin film is provided on the inner wall surface of the formed slab, and cutting is performed from the back side of the ruthenium substrate to the groove. A method of dividing a substrate into a plurality of pellets by rubbing a substrate.

Compared with the usual procedure for performing wafer thinning after thinning the workpiece, this method is not required to operate the thinned workpiece, and is excellent in that it can eliminate the risk of damage of the workpiece.

Moreover, regarding the risk of the above (2), the deterioration of the flexural strength of the wafer is the main cause of damage.

As a method of dividing a workpiece for improving the flexural strength of a wafer, a method of "stealth Dicing (registered trademark)" disclosed in Patent Document 2 is known.

The stealth cutting method is a method in which a modified region is formed in a workpiece by laser light, and a modified region is used as a cutting starting point by applying a force to the workpiece, and the workpiece is cut to form a wafer.

More specifically, the surface of the workpiece is stretched on one side of the workpiece, and the surface opposite to the surface on which the film is formed is used as a laser light incident surface, and the laser light is irradiated by aligning the light collecting points to The interior of the workpiece, due to multiphoton absorption, forms a modified region. Then, the cutting target line along the workpiece is formed by the modified region, and a cutting starting point region is formed on the laser light incident surface from the inside of the predetermined distance, and the film can be stretched by stretching the film. The starting point region is used as a starting point, and the wafer is obtained by cutting the workpiece at a plurality of portions of the workpiece so as to be spaced apart from each other.

Since such a method does not involve the process of cutting a workpiece by a rotary blade, it is possible to suppress so-called chipping in which a minute defect occurs at the edge portion of the wafer, and the flexural strength of the wafer can be improved.

Further, as a method of collectively avoiding the risks of the above (1) and (2), there is a method of the patent document 3 proposed.

Patent Document 3 discloses that after the modified region is formed inside the workpiece by the above-described invisible cutting (registered trademark), the workpiece is pressed from the back surface of the workpiece to make the workpiece thinner and easily cut, and then the processing pressure by the grinding stone or the like is used. A method of cutting into individual wafers.

Prior technical literature Patent literature

Patent Document 1 Japanese Patent Publication No. 06-085055

Patent Document 2 Japanese Patent Laid-Open Publication No. 2003-334812

Patent Document 3 Japanese Patent Laid-Open Publication No. 2004-111428

However, the back grinding step of the workpiece is performed while rinsing the grinding debris generated during the polishing to expose one side of the workpiece to the ultrapure water.

In the method disclosed in Patent Document 3, if the modified region is cut by the grinding of the workpiece (cracking), since the gap between the cut portions is extremely narrow, water (sewage) is further caused by capillary phenomenon. Strongly penetrate into the gap that is cut. On the surface opposite to the polishing surface of the workpiece, there is a case where an electric circuit or the like is formed, and an adhesive sheet having an adhesive layer is usually attached to protect the surface.

However, water (sewage) which penetrates into the gap due to vibration during grinding penetrates into the interface between the adhesive layer and the protected surface of the workpiece, and dissolves the water of the adhesive, causing contamination of the protected surface. In Patent Document 3, a method for suppressing contamination of such a protected surface has not been discussed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface protection sheet which is suitable as a surface protection sheet for use in a step of grinding a back side of a workpiece on which a modified region is formed, and which suppresses a gap formed by breakage of water from the workpiece during a back grinding step of the workpiece. Infiltration (sewage infiltration) to the protected surface of the workpiece prevents contamination of the protected surface of the workpiece.

The present inventors have found that a surface protective sheet which forms an adhesive layer conforming to a specific requirement on a substrate conforming to a specific requirement can solve the above problems.

That is, the present invention provides the following [1] to [8]:

[1] A surface protective sheet which is a surface protective sheet having an adhesive layer on a substrate, which conforms to the following requirements (a) to (d): (a) the Young's modulus of the substrate is 450 MPa or more; b) the storage modulus of the adhesive layer at 25 ° C is 0.10 MPa or more; (c) the storage modulus of the adhesive layer at 50 ° C is 0.20 MPa or less; (d) the thickness of the adhesive layer is 30 μm or more.

[2] The surface protection sheet according to [1] above, wherein the adhesive layer comprises an energy ray-curable adhesive composition.

[3] The surface protection sheet according to [1] or [2], wherein the substrate has a thickness of 5 to 250 μm.

[4] The surface protection sheet according to any one of [1] to [3] wherein the substrate comprises a polyester film as a resin film.

[5] The surface protection sheet according to any one of the above [1], wherein the substrate has a resin film, and a non-energy hardening type having a thickness of 10 μm or less laminated on the resin film. The second adhesive layer of the adhesive composition or the easy-adhesion layer having a thickness of 10 μm or less.

[6] The surface protection sheet according to any one of [1] to [5] wherein the surface protection sheet is in a grinding step of a workpiece in which a modified region is formed, and is modified by grinding of the workpiece. When the material region is cracked and a gap is formed in the workpiece, it is attached to the workpiece.

[7] The surface protection sheet according to [6] above, wherein the surface protection sheet is attached to a surface of the workpiece on which irregularities are formed.

[8] The surface protection sheet according to [6] or [7] above, wherein the surface protection sheet is attached to a workpiece heated to 40 to 80 °C.

The surface protection sheet of the present invention prevents penetration of water (infiltration of sewage) into the protected surface of the workpiece from the gap formed by the cutting of the workpiece during the grinding step of the back side of the workpiece, thereby preventing contamination of the protected surface of the workpiece. Therefore, it is suitable as a surface protection sheet which can be used as a back side grinding step of a workpiece which can be used for forming a modified region.

1, 1a, 1b‧‧‧ surface protection film

11‧‧‧Substrate

12‧‧‧Adhesive layer

13‧‧‧ peeling material

50‧‧‧Workpiece

50a‧‧‧ back side surface of the workpiece

51‧‧‧ concave part

52‧‧‧Modified area

53‧‧‧ gap

Fig. 1 (a) and (b) are cross-sectional views showing a surface protective sheet which is an example of the configuration of the surface protective sheet of the present invention.

Fig. 2 (a) and (b) are schematic views showing an example of the use of the surface protective sheet of the present invention.

[Formation of the Invention]

In the following description, the "weight average molecular weight (Mw)" is a value in terms of polystyrene measured by a gel permeation chromatography (GPC) method, specifically, a value measured by the method described in the examples. .

Further, the thickness of the base material (including the resin film constituting the base material, the second adhesive layer, and the easy-adhesive layer), the adhesive layer, and the release material, which are the surface protective sheets, is based on the value measured in accordance with JIS K7130, specifically The values measured according to the methods described in the examples.

Further, for example, "(meth)acrylate" is a word indicating "acrylic ester" and "methacrylic acid ester", and is similar to other similar terms.

[Composition of surface protection sheet]

The surface protection sheet of the present invention is not particularly limited as long as it has an adhesive layer on a substrate, and examples thereof include a surface protection sheet having the structure shown in Fig. 1.

The surface protective sheet 1a of Fig. 1(a) has a structure in which the adhesive layer 12 is provided on the substrate 11, but the surface protective sheet 1b of Fig. 1(b) may further have peeling on the adhesive layer 12. Material 13. Further, the release material 13 is removed when the surface protection sheet is attached to a workpiece or the like.

Further, the surface protection sheet of the present invention may be subjected to a release treatment on the surface opposite to the surface of the adhesive layer 12 of the substrate 11 on which the surface protection sheet 1a is formed, and the surface of the surface protection sheet 1a may be wound into a roll. Protective sheet.

Here, the substrate 11 may be a single layer or a multilayer layer including two or more layers. Further, the substrate 11 may have a structure in which a second adhesive layer or an easy-adhesion layer different from the adhesive layer 12 is laminated on a resin film including a single layer or a plurality of layers. The details of the substrate 11 are described later.

Moreover, the surface protection sheet of the present invention meets the following requirements (a) to (d): (a) the Young's modulus of the substrate is 450 MPa or more; (b) the storage modulus of the adhesive layer at 25 ° C It is 0.10 MPa or more; (c) the storage modulus of the adhesive layer at 50 ° C is 0.20 MPa or less; (d) the thickness of the adhesive layer is 30 μm or more.

Further, the Young's modulus of the substrate is a value measured in accordance with JIS K7127 (1999), specifically, a value measured by the method described in the examples.

Further, the storage modulus of the adhesive layer at 25 ° C and 50 ° C is a value measured by the method described in the examples, and the adhesive layer is composed of an energy ray-curable adhesive composition, meaning that the energy is irradiated. The storage modulus at 25 ° C and 50 ° C before the line.

By conforming to the above requirements (a) and (b), it is possible to suppress the deformation of the surface protection sheet attached to the workpiece due to the vibration at the time of grinding of the workpiece, and to suppress the penetration of the sewage into the protected surface of the workpiece.

Further, by conforming to the above requirement (c), when the workpiece is heated and the surface protection sheet is attached (thermally attached) to the uneven portion of the circuit or the like, the adhesive layer follows the uneven portion of the workpiece, and the uneven portion of the workpiece is reduced. The non-contact area of the adhesive layer. As a result, it is possible to suppress the occurrence of the infiltration of the sewage into the peeled region by the presence of the non-contact region as the opening end of the adhesive layer peeling off from the workpiece.

Further, by conforming to the above requirement (d), irregularities such as electric circuits are formed on the adhering surface of the workpiece, and the non-contact region between the uneven portion of the workpiece and the adhesive layer can be reduced. As a result, as in the above, it is possible to suppress The presence of the non-contact region serves as a phenomenon in which the sewage penetrates into the peeled region as the adhesive layer is peeled off from the workpiece.

<Substrate>

The substrate used in the present invention is not particularly limited as long as it meets the above requirements (a).

The substrate may be a single layer film containing one type of resin film, or may be a multilayer film including a resin film containing a plurality of layers.

Further, when the surface protective sheet is peeled off from the wafer after the wafer is manufactured from the workpiece, the resin film can be formed and formed on the resin film from the viewpoint of exhibiting excellent adhesion of the surface protective sheet to the wafer. The second adhesive layer (hereinafter also referred to simply as "second adhesive layer") of the non-energy-curable adhesive composition or the substrate of the easy-adhesion layer.

The thickness of the substrate used in the present invention is preferably 5 to 250 μm, more preferably 10 to 200 μm, still more preferably 15 to 150 μm, still more preferably 20 to 110 μm. When the thickness of the substrate is 5 μm or more, the deformation resistance (size stability) at a high temperature is excellent. On the other hand, when the thickness of the base material is 250 μm or less, it is easy to adjust the Young's modulus to a predetermined value or more.

In the present invention, the "thickness of the substrate" means the entire thickness of the constituent substrate. For example, for a substrate in which a plurality of resin films are laminated, the total thickness of all the resin films laminated is the thickness of the substrate; and the substrate having the resin film, the second adhesive layer or the easy-adhesion layer described above The total thickness of the resin film and the second adhesive layer or the easy-adhesion layer is the thickness of the substrate.

As defined in the above requirement (a), the Young's modulus of the substrate used in the present invention is 450 MPa or more, preferably 500 MPa or more, more preferably 1,000 MPa or more, still more preferably 1,500 MPa or more.

When the Young's modulus of the substrate is less than 450 MPa, the surface protective sheet attached to the workpiece is easily deformed due to the vibration during polishing of the workpiece, and it is difficult to inhibit the penetration of the sewage into the protected surface of the workpiece, which is not preferable.

Further, the upper limit of the Young's modulus of the substrate used in the present invention is not particularly limited, but the Young's modulus of the substrate is preferably 10,000 MPa or less, more preferably 7,000 MPa or less.

In addition, the Young's modulus of the substrate specified in the above-mentioned requirement (a) can be adjusted, for example, by appropriately setting the type of the resin film used as the substrate, and by forming the resin film as a substrate. The type, thickness, and number of layers of the resin film to be laminated, and the material for forming the layer and the film thickness of the layer in the case where the second adhesive layer or the easy-adhesion layer are provided are adjusted as appropriate.

The adjustment method of the Young's modulus of the substrate can be adjusted, for example, according to the following trends (1) to (3). Further, in the present invention, the Young's modulus adjustment method of the substrate is not limited by the method according to the following tendency, and the following tendency is merely exemplified.

(1) In the case of a substrate containing a resin film containing a resin having a cyclic structure based on a polyester film or a polycarbonate film, it is easy to adjust the Young's modulus of the substrate. The tendency to become a specified value or more.

(2) By forming a substrate containing a low-density polyester film, the Young's modulus of the substrate is lowered.

(3) In a substrate containing a resin film containing a resin having a cyclic structure in a main chain, the shorter the linear structure length of the polymer main chain, the higher the Young's modulus. For example, even if they are the same The polyester film has a Young's modulus of a substrate containing a polyethylene terephthalate having a relatively short linear structure and a polyethylene terephthalate having a relatively long linear structure. The material is high.

(resin film)

The resin film contained in the substrate of the present invention is preferably a film having a high thickness accuracy from the viewpoint of stably holding the workpiece even when the workpiece is extremely thin. For example, a polyester film or a polycarbonate is used. An ester film, a polystyrene film, a polyphenylene sulfide film, a cycloolefin polymer film, or the like.

Among these, from the above viewpoints, and from the viewpoint of easily adjusting the Young's modulus of the substrate to conform to the above-described requirement (a), a polyester film is preferable.

The polyester constituting the polyester-based film may, for example, be a polyester obtained by polycondensation of an aromatic dibasic acid or an ester derivative thereof with a diol or an ester derivative thereof.

Specific examples of the polyester-based film include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalene. A film of a polyester such as a formate. Further, it may be a film containing a copolymer of the above polyester, or a film containing a mixture of the above polyester and a small amount of other resin.

Among these, a polyethylene terephthalate film is preferred from the viewpoints of easy to obtain, high thickness accuracy, and easy adjustment of the Young's modulus of the substrate to conform to the above-described requirement (a). .

Further, a base material containing only a polyester film is used, and an adhesive layer containing an energy ray-curable adhesive is formed on the polyester film. In the case where the adhesive is hardened by the irradiation of the energy ray, the volume shrinkage of the adhesive occurs, and the interface adhesion between the substrate and the adhesive layer is lowered to cause interface damage between the substrate and the adhesive layer. . Therefore, there is a case where the peeling property of the surface protective sheet will be lowered.

In order to avoid such a drawback, it is preferred to form a multi-layer film by laminating a resin film such as a low-density polyethylene film on a polyester film. Further, a second adhesive layer or an easy-adhesion layer to be described later may be provided on the polyester film.

Further, in the resin film, a conventional filler, a colorant, an antistatic agent, an antioxidant, an organic lubricant, a catalyst, or the like may be contained within the range of the substrate satisfying the above requirement (a).

Further, the resin film may be transparent, and may be colored or vapor-deposited as needed.

(2nd adhesive layer / easy adhesion layer)

The substrate to be used in the present invention is preferably a substrate having a resin film, a second adhesive layer containing a non-energetic curing adhesive deposited on the resin film, or an easy-adhesion layer. Further, the second adhesive layer is different from the adhesive layer that satisfies the above requirements (b) to (d).

For the thickness accuracy of the resin film before the formation of the second adhesive layer or the easy-adhesion layer, the thickness of the substrate can be easily avoided because the influence of the second adhesive layer or the easy-adhesion layer is small. Adjustments become difficult forms.

By providing the second adhesive layer or the easy-adhesion layer on the resin film, it is possible to exhibit excellent releasability in which the adhesive of the surface protective sheet does not adhere to the wafer when the surface protective sheet is peeled off from the wafer.

The reason is as follows. That is, when a substrate containing only a polyester film is used and an energy ray-curable adhesive is used for the formation of the adhesive layer, as described above, when the adhesive is hardened by the irradiation of the energy ray, it is generated. The volume shrinkage of the adhesive, the interface adhesion between the substrate and the adhesive layer is lowered, and interface damage occurs between the substrate and the adhesive layer. However, by providing the second adhesive layer or the easy-adhesion layer, such defects can be avoided, and excellent peelability can be exhibited.

The adhesive composition forming the second adhesive layer is preferably an adhesive resin containing an acrylic resin, a rubber resin, or a polyoxyn resin.

Further, the adhesive composition for forming the second adhesive layer may contain a crosslinking agent, a photoinitiator, an antioxidant, a softener (plasticizer), a filler, a rust preventive, and a pigment as necessary. , dyes, etc.

In the case where the adhesive layer is formed by the application of the adhesive composition, it is possible to further add an organic solvent to form an adhesive layer from the viewpoint of improving the coatability of the resin film or the like and facilitating the formation of the adhesive layer. The form of the solution of the agent composition.

The thickness of the second adhesive layer is preferably 10 μm or less, more preferably 0.3 to 8 μm, still more preferably 1 to 6 μm. When the thickness of the second adhesive layer is 10 μm or less, even if unevenness occurs in the thickness of the second adhesive layer, the influence on the thickness accuracy of the entire substrate is small.

The composition for forming an easy-contact layer which forms an easy-adhesion layer is not particularly limited, and for example, a polyester-based resin, an urethane-based resin, a polyester urethane-based resin, an acrylic resin, or the like can be used. Composition.

Among these, the composition for forming an easy-to-adhere layer which forms an easy-adhesion layer preferably contains a compound having an energy ray-polymerizable group.

The energy ray-polymerizable group is a group which is polymerized by irradiation with an energy ray such as an ultraviolet ray or an electron beam, and examples thereof include a group having an ethylenically unsaturated bond such as a (meth) acryl fluorenyl group, a vinyl group or an aryl group. Among these, a compound having a (meth) acrylonitrile group is preferred.

Examples of the compound having a (meth) acrylonitrile group include urethane (meth) acrylate, (meth) acrylate modified polyester, and the like.

The adhesive layer is formed by using a composition containing a compound having such an energy ray-polymerizable group, and after the hardening of the energy ray-curable adhesive, the adhesion between the resin film and the adhesive layer is maintained via the easy-adhesion layer. .

Therefore, even when the polyester film is used as a resin film, the peeling property of the surface protective sheet can be improved.

Further, the composition for forming an easy-adhesion layer may contain a crosslinking agent, a photoinitiator, an antioxidant, a softener (plasticizer), a filler, a rust preventive agent, and the like as necessary. Pigments, dyes, etc.

In addition, in the case where the adhesive layer is formed by the application of the adhesive composition, it is possible to further add an organic solvent from the viewpoint of improving the coatability of the resin film or the like and facilitating the formation of the easy-adhesion layer. The form of the solution of the layer forming composition.

Further, from the same viewpoint as described above, the thickness of the easy-adhesion layer is preferably 10 μm or less, more preferably 0.3 to 7 μm, still more preferably 0.5 to 5 μm.

As a method of forming the second adhesive layer and the easy-adhesion layer, an organic solvent may be added to form the composition as a solution, and then the solution may be applied onto a resin film according to a conventional coating method. Further, it is preferred that the coating film formed after coating is dried at 50 to 120 ° C to form a second adhesive layer or an easy-adhesion layer.

<Adhesive layer>

The protective sheet of the surface protective sheet of the present invention has a storage modulus at 25 ° C of 0.10 MPa or more, preferably 0.12 MPa or more, more preferably 0.14 MPa or more, as specified in the above requirement (b). Good is 0.17MPa or more.

If the storage modulus of the adhesive layer at 25 ° C is less than 0.10 MPa, the surface protection sheet attached to the workpiece is easily deformed due to the vibration during the grinding of the workpiece, and it is difficult to inhibit the penetration of the sewage into the protected surface of the workpiece, which is not preferable. .

Further, although the upper limit of the storage modulus of the adhesive layer at 25 ° C is not particularly limited, the storage modulus of the adhesive layer at 25 ° C is preferably 1.00 MPa or less.

Further, as defined in the above requirement (c), the surface protective sheet of the present invention has a storage modulus at 50 ° C of 0.20 MPa or less, preferably 0.16 MPa or less, more preferably 0.13 MPa or less. More preferably, it is 0.10 MPa or less.

If the storage modulus of the adhesive layer at 50 ° C exceeds 0.20 MPa, when the workpiece is heated and the surface protective sheet is attached (thermally attached) to the uneven portion of the circuit or the like, the uneven portion and the adhesive layer of the workpiece are insufficient. Contact, and there is a tendency for the non-contact area to expand around the concavo-convex portion of the workpiece. Its knot As a result of the presence of the non-contact region as the adhesive layer from the beginning of the peeling of the workpiece, the infiltration of the sewage into the peeled region is not preferable.

Further, the lower limit of the storage modulus at 50 ° C as the adhesive layer is not particularly limited, and the storage modulus of the adhesive layer at 50 ° C is preferably 0.01 MPa or more, more preferably 0.06 MPa or more.

The storage modulus of the adhesive layer specified in the above requirements (b) and (c) at 25 ° C and 50 ° C can be adjusted by appropriately changing the composition of the adhesive composition forming the adhesive layer.

In other words, by appropriately setting the type of the adhesive resin contained in the adhesive composition, the functional group, the weight average molecular weight, the type of the monomer constituting the resin, and the content of the constituent unit derived from the monomer, The storage modulus of the formed adhesive layer is adjusted to be within the above range.

The adjustment method for the storage modulus of the more specific adhesive layer at 25 ° C and 50 ° C can be adjusted, for example, according to the following tendency (1) to (4). Further, in the present invention, the adjustment method of the storage modulus of the adhesive layer at 25 ° C and 50 ° C is not limited by the method according to the following tendency, and the following tendency is merely exemplified.

(1) When an acrylic resin, preferably an acrylic copolymer, is used as the adhesive resin, the storage modulus of the formed adhesive layer can be easily adjusted to fall within the above range.

(2) When a monomer having a high glass transition temperature of a homopolymer such as methyl (meth) acrylate is used as the acrylic copolymer of the constituent unit, the storage modulus of the formed adhesive layer rises. The tendency. Relative to all constituent units of the acrylic copolymer, derived from such The more the content ratio of the constituent units of the monomer increases, the more the storage modulus tends to increase.

(3) In the case where an adhesive layer is formed from the energy ray-curable adhesive composition, there is a tendency as follows. In other words, by using an energy ray-curable adhesive resin (II) to be described later, an adhesive composition containing an adhesive film (I) and an energy ray-curable low molecular compound containing both a non-energetic curing type is used. In contrast, since the energy ray-curable low molecular compound is not contained or the content of the compound can be reduced, it is easy to adjust the storage modulus to fall within the above range.

(4) In the case where the non-energy ray-curable adhesive resin (I) or the energy ray-curable adhesive resin (II) described later is crosslinked, the storage modulus tends to increase. Further, the higher the degree of crosslinking, the higher the storage modulus tends to increase.

Further, as defined in the above requirement (d), the surface protective sheet of the present invention has a thickness of the adhesive layer of 30 μm or more, preferably 32 μm or more, more preferably 35 μm or more, still more preferably 38 μm or more.

If the thickness of the adhesive layer is less than 30 μm, irregularities such as electric circuits are formed on the adhered surface of the workpiece, and the uneven portion of the workpiece is not in sufficient contact with the adhesive layer, and the non-contact region is expanded around the uneven portion of the workpiece. The tendency. As a result, since the presence of the non-contact region is caused by the infiltration of the sewage into the peeled region as the adhesive layer from the beginning of the peeling of the workpiece, it is not preferable.

Further, although the upper limit of the thickness of the adhesive layer is not particularly limited, the thickness of the adhesive layer is preferably 200 μm or less.

The adhesive layer of the surface protective sheet of the present invention is preferably formed of an energy ray-curable adhesive composition. By hardening the energy ray to the adhesive layer, the adhesion of the surface protection sheet can be reduced, so that the wafer on the surface protection sheet that has been polished/divided can be transferred to a pickup sheet, a crystal grain. It is easy to remove the surface protection sheet by adhering to other sheets such as a film.

Further, in the present invention, the "energy line" means ultraviolet rays, electron beams, etc., and is preferably ultraviolet rays.

The energy ray-curable adhesive composition includes a non-energy curing type adhesive resin (I) (hereinafter also referred to as "adhesive resin (I)") and an energy ray-curable low molecular compound. The adhesive composition (I) or an energy ray-curable adhesive resin (II) containing a side chain in which an unsaturated group is introduced into the non-energy ray-curable adhesive resin (I) (hereinafter, also referred to as Adhesive composition (II) of "adhesive resin (II)"). In the present invention, the term "adhesive resin" also includes a resin which exhibits adhesiveness by addition of a plasticizing component, etc., which does not substantially have an adhesive property. The concept.

The weight average molecular weight (Mw) of the non-energy curing type adhesive resin (I) is preferably from 250,000 to 1.5 million, more preferably from 350,000 to 1.3 million, and even more preferably from 450,000 to 1.1 million, and yet more Good for 650,000 ~ 1.05 million.

Moreover, the weight average molecular weight (Mw) of the energy ray-curable adhesive resin (II) which introduces an unsaturated group into a side chain is preferably 300,000 to 1,600,000, more preferably 400,000 to 1,400,000. The best is 500,000 to 1.2 million, and the better is 700,000 to 1.1 million.

Examples of the non-energy ray-curable adhesive resin (I) include an acrylic resin, a rubber-based resin, and a polyfluorene-based resin.

Among these, an acrylic resin is preferred from the viewpoint of easily forming an adhesive layer satisfying the conditions (b) and (c). Hereinafter, the acrylic resin will be described in detail.

(acrylic resin)

The acrylic resin is preferably a resin containing a structural unit (p1) derived from a carbonic acid alkyl (meth)acrylate monomer (hereinafter also referred to as "monomer (p1)").

The acrylic resin may be a homopolymer containing only the constituent unit (p1) derived from the above monomer (p1), but from the viewpoint of obtaining the adhesive layer satisfying the conditions (2) and (3), it is preferred to simultaneously a constituent unit (p2) and/or a source containing a constituent unit (p1) and further containing an alkyl (meth)acrylate monomer (hereinafter also referred to as "monomer (p2)") having a carbon number of 1 to 3 A copolymer of a constituent unit (p3) of a monomer (p3) containing a functional group (hereinafter also referred to as "monomer (p3)").

The carbon number of the alkyl group which the monomer (p1) has is preferably from 4 to 20, more preferably from 4 to 12, still more preferably from 4 to 6, from the viewpoint of improving the adhesion of the adhesive sheet. Further, the alkyl group of the monomer (p1) may be either a straight chain or a branched chain.

Examples of the monomer (p1) include butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Octyl methacrylate, lauryl (meth)acrylate, (meth) acrylate stearate, and the like.

Further, these monomers (p1) may be used singly or in combination of two or more.

Among these, from the viewpoint of improving the adhesion of the adhesive sheet, butyl (meth)acrylate is preferred.

In the case where the acrylic resin is a copolymer, the content of the constituent unit (p1) is preferably 40 to 98% by mass, more preferably 45 to 95% by mass, even more preferably the total constituent unit of the acrylic resin. 50 to 90% by mass.

Examples of the monomer (p2) include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate.

Further, these monomers (p2) may be used singly or in combination of two or more.

Among these, from the viewpoint of obtaining the adhesive layer satisfying the conditions (b) and (c), methyl (meth)acrylate is preferred.

In the case where the acrylic resin is a copolymer, the content of the constituent unit (p2) is preferably from 1 to 30% by mass, more preferably from 3 to 26% by mass, even more preferably the total constituent unit of the acrylic resin. 6~22% by mass.

The monomer (p3) means a monomer having a functional group which can react with a crosslinking agent to be described later and which can serve as a starting point of crosslinking or a functional group having a crosslinking promoting effect.

The functional group of the monomer (p3) may, for example, be a hydroxyl group, a carboxyl group, an amine group or an epoxy group. Among these, a carboxyl group or a hydroxyl group is preferred from the viewpoint of reactivity with a crosslinking agent.

Examples of the monomer (p3) include a monomer having a hydroxyl group, a monomer having a carboxyl group, a monomer having an amine group, and a monomer having an epoxy group.

These monomers (p2) may be used singly or in combination of two or more.

Among these, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and more preferably a hydroxyl group-containing monomer are preferable.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate. Bases of 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth) acrylate, hydroxyalkyl (meth) acrylate such as 4-hydroxybutyl (meth) acrylate; vinyl alcohol, allylic An unsaturated alcohol such as an alcohol.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; fumaric acid, methylene succinic acid, and maleic acid; An ethylenically unsaturated dicarboxylic acid such as methyl maleic acid or an acid anhydride thereof; 2-carboxyethyl methacrylate or the like.

In the case where the acrylic resin is a copolymer, the content of the constituent unit (p3) is preferably from 1 to 35 mass%, more preferably from 3 to 32 mass%, more preferably all of the constituent units of the acrylic resin. 6 to 30% by mass.

Further, the acrylic resin used in the present invention may contain, in addition to the above structural units (p1) to (p3), styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate. A constituent unit of a monomer in which an acrylic monomer such as acrylonitrile or acrylamide is copolymerized.

(Energy hardening type low molecular compound)

The energy ray-curable compound to be blended in the adhesive composition (I) is preferably a monomer or oligomer which has an unsaturated group in the molecule and is polymerizable and hardenable by irradiation with an energy ray.

Examples of such an energy ray-curable compound include trimethylolpropane tri(meth)acrylate, pentaerythritol (meth) acrylate, pentaerythritol tetra(meth) acrylate, and dipentaerythritol hexa(methyl). a poly (meth) acrylate monomer such as acrylate, 1,4-butanediol di(meth) acrylate or 1,6-hexane diol (meth) acrylate; ethyl urethane (A) Acrylate, polyester (meth) acrylate, polyether (meth) acrylate, (meth) acrylate epoxy ester, and the like.

Among these, urethane (meth) acrylate or urethane (meth) acrylate oligomer is preferred from the viewpoints of high molecular weight and difficulty in lowering the storage modulus of the adhesive layer. Things.

The molecular weight of the energy ray-curable compound (the weight average molecular weight in the case of the oligomer) is preferably from 100 to 12,000, more preferably from 200 to 10,000, still more preferably from 400 to 8,000, still more preferably from 600 to 6,000.

The content of the energy ray-curable compound in the adhesive composition (I) is preferably 40 to 200 parts by mass, more preferably 50 to 150 mass, based on 100 parts by mass of the non-energy ray-curable adhesive resin. More preferably, it is 60 to 90 parts by mass.

(Energy curing type adhesive resin (II))

The adhesive resin (II) is an adhesive resin in which an unsaturated group is introduced into the side chain of the non-energy ray-curable adhesive resin (I).

The above-mentioned adhesive resin (I) can be used as the main chain of the adhesive resin (II), but from the viewpoint of easily forming the adhesive layer satisfying the above conditions (b) and (c), an acrylic resin is preferable. It is preferred to have an acrylic copolymer having constituent units (p1), (p2), and (p3).

The unsaturated group which is contained in the side chain of the adhesive resin (II) may, for example, be a (meth)acryl fluorenyl group, a vinyl group or an aryl group, and is preferably a (meth) acrylonitrile group.

In the synthesis method of the adhesive resin (II), for example, a functional group-containing monomer is copolymerized to the adhesive resin (I) to form a functional group, and a substituent having a bond with the functional group is added, and A method of obtaining a compound of a saturated group by bonding a functional group of the copolymer to the substituent.

Examples of the monomer containing a functional group copolymerized with the adhesive resin (I) include the compounds exemplified as the above monomer (p3).

Examples of the substituent bonded to the functional group include an isocyanate group or a glycidyl group.

Therefore, examples of the compound having both a substituent and an unsaturated group which may be bonded to the functional group include (meth)acryloyloxyethyl isocyanate and (meth)acrylonitrile isocyanate. Base) propylene acrylate and the like.

(crosslinking agent)

It is preferred that the adhesive compositions (I) and (II) further contain a crosslinking agent.

The main purpose of adding a crosslinking agent is non-energy hardening adhesion derived from a functional group or the like derived from the monomer (p2) of the above acrylic resin. The functional group on the side chain of the adhesive resin (I) or the energy ray-curable adhesive resin (II) reacts to crosslink the adhesive resin.

Examples of the crosslinking agent include isocyanate-based diisocyanate, hexamethylene diisocyanate, and isocyanate-based crosslinking agents such as these adducts; and epoxy resins such as ethylene glycol epoxypropyl ether. Crosslinking agent; hexa[1-(2-methyl)-aziridinyl]triphosphate (Ethyleneimine-based crosslinking agent such as triphosphatriazine); a chelating agent such as an aluminum chelating agent; These crosslinking agents may be used singly or in combination of two or more.

Among these, an isocyanate crosslinking agent is preferred from the viewpoint of improving the cohesive force and improving the adhesion, and from the viewpoint of ease of availability.

The blending amount of the crosslinking agent is appropriately adjusted depending on the number of functional groups in the structure of the adhesive resin (I) and (II), but from the viewpoint of accelerating the crosslinking reaction, with respect to the adhesive resin (I) and (II) In terms of 100 parts by mass, it is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, still more preferably 0.05 to 4 parts by mass.

(photopolymerization initiator)

Further, in the adhesive resins (I) and (II), it is preferred to further contain a photopolymerization initiator. By containing a photopolymerization initiator, the hardening reaction can be sufficiently performed even with a lower energy energy ray such as ultraviolet rays.

Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyl phenyl sulfide, and monosulfide. Tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, diacetyl, 8-chloropurine, and the like.

These photopolymerization initiators may be used singly or in combination of two or more.

The blending amount of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, even more preferably 0.05, based on 100 parts by mass of the adhesive resins (I) and (II). ~2 parts by mass.

(other additives)

In the adhesive resins (I) and (II), other additives may be contained within a range not impairing the effects of the present invention.

Examples of other additives include an antioxidant, a softener (plasticizer), a filler, a rust preventive, a pigment, a dye, and the like.

In the case of blending the additives, the blending amount of the additive is preferably 0.01 to 6 parts by mass based on 100 parts by mass of the adhesive resin (I) and (II).

In the adhesive resin (I) and (II), from the viewpoint of improving the coating property to the substrate or the release sheet, it may be further diluted with an organic solvent to form a solution of the adhesive composition.

Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, and Alkane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, and the like.

Further, as the organic solvent, the organic solvent used in the formation of the adhesive resins (I) and (II) can be used as it is, and the organic solvent used in the preparation can be added in such a manner that the adhesive composition solution can be uniformly applied. One or more organic solvents other than the above.

The solid content concentration of the solution of the adhesive compositions (I) and (II) is preferably from 5 to 60% by mass, more preferably from 10 to 45% by mass, even more preferably from 15 to 30% by mass. Way to blend organic solvents.

<release material>

Further, the surface protection sheet of the present invention may further have a release material on the adhesive layer.

Examples of the release material include a release sheet which is subjected to double-side peeling treatment, a release sheet which has been subjected to single-side peeling treatment, and the like, and a release agent is applied to a substrate for a release material.

Examples of the substrate for the release material include a polyester resin film such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; and polypropylene. A plastic film such as a polyolefin resin film such as a resin or a polyethylene resin.

Examples of the release agent include a rubber-based elastomer such as a polyfluorene-based resin, an olefin-based resin, an isoprene-based resin, and a butadiene-based resin, a long-chain alkyl-based resin, and an alkyd-based resin. Fluorine resin or the like.

Although the thickness of the release material is not particularly limited, it is preferably from 10 to 200 μm, more preferably from 25 to 150 μm.

(Method of manufacturing surface protection sheet)

The method for producing the surface protective sheet of the present invention is not particularly limited, and can be produced by a conventional method. For example, a method of producing a solution of an adhesive composition containing the above organic solvent by a conventional coating method can be mentioned.

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 sheet coating method, a die coating method, a gravure coating method, and the like. .

As a specific manufacturing method, as shown in Fig. 1(a), the surface protective sheet 1a having the adhesive layer 12 formed on the substrate 11 is manufactured. The production method may, for example, be a method in which the adhesive composition solution is directly applied to one side surface of the substrate 11 and dried to form the adhesive layer 12, or a method in which the adhesive composition solution is directly applied to the release material. The method of drying the surface to form the adhesive layer 12 on the release material, bonding the adhesive layer 12 and the substrate 11, and then removing the release material, and the like.

Moreover, as shown in FIG. 1(b), as a method of producing the adhesive sheet 1c in which the release material 13 is laminated on the adhesive layer 12 formed on the substrate 11, for example, the adhesion described above can be mentioned. A method of manufacturing the surface of the adhesive layer 12 of the sheet 1a and the release material 13; or applying the adhesive composition solution directly to the release-treated surface of the release material 13, and drying it to form an adhesive layer 12 on the release material 13. A method of manufacturing the adhesive layer 12 and the substrate 11 and the like.

The solid content concentration of the adhesive composition solution in the case of blending the organic solvent is preferably from 10 to 60% by mass, more preferably from 12 to 45% by mass, still more preferably from 15 to 30% by mass.

Further, it is preferred that the solution in which the adhesive composition is dissolved in an organic solvent is applied to the peeling layer of the substrate or the release material, and then heated at a temperature of 80 to 150 ° C for 30 seconds to 5 minutes.

[Use of surface protection sheet]

Hereinafter, the use of the surface protective sheet of the present invention will be described.

The surface protection sheet of the present invention is suitable for the surface protection sheet used as the back side polishing step of the workpiece on which the modified region is formed, and can suppress the gap leakage formed by the breakage of water from the workpiece during the back grinding step of the workpiece. Ingress (sewage infiltration) to the protected surface of the workpiece prevents contamination of the protected surface of the workpiece.

Fig. 2 is a schematic view showing an example of the use of the surface protective sheet of the present invention.

As shown in Fig. 2(a), the surface protection sheet of the present invention is suitable as a surface protection sheet for a workpiece 50 such as a semiconductor wafer in which the uneven portion 51 is formed by a circuit or the like. By attaching the surface protection sheet 1 of the present invention to the surface on which the unevenness is formed (the uneven portion 51 side), the step protection circuit can be cut on the back side of the workpiece.

When the surface protection sheet of the present invention is attached to the uneven portion 51 side of the workpiece 50, it is preferable to heat the workpiece. The heating temperature as the workpiece is preferably 40 to 80 ° C, more preferably 45 to 60 ° C.

Further, since the surface protection sheet of the present invention conforms to the above requirements (c) and (d), the adhesive layer 12 follows the uneven portion 51 of the workpiece 50, and the non-contact region of the uneven portion 51 of the workpiece 50 and the adhesive layer 12 can be reduced. As a result, it is possible to suppress the phenomenon in which the presence of the non-contact region is the end portion of the adhesive layer 12 peeled off from the workpiece 50, and the sewage is infiltrated into the peeled region.

Moreover, the modified region 52 is formed in the workpiece 50 by the method of stealth cutting (registered trademark) described in Patent Document 2, for example. The formation of the modified region 52 may be performed before the surface protection sheet 1 is attached to the workpiece 50, or may be performed after attachment.

Then, after the surface protection sheet 1 of the present invention is attached to the uneven portion 51 side of the workpiece 50, it undergoes a cutting step of cutting the workpiece from the back side surface 50a of the workpiece to form a desired thickness.

This cutting step is performed for rinsing the generated chips, and the workpiece 50 is immersed in ultrapure water while being immersed in ultrapure water.

As shown in Fig. 2(b), as the workpiece is cut, the modified region 52 inside the workpiece 50 is cut to form the gap 53.

In the case of using a conventional surface protection sheet, water (sewage) penetrates into the gap 53 by the capillary phenomenon, the interface between the circuit surface which penetrates to the side of the uneven portion 51 and the adhesive layer 12, and the circuit surface of the contaminated workpiece Disadvantages.

However, the surface protection sheet of the present invention can suppress the deformation of the surface protection sheet attached to the workpiece due to the vibration during polishing of the workpiece by conforming to the above requirements (a) and (b), and suppress the penetration of the sewage into the workpiece. Protected surface.

After the cutting step is completed, other sheets such as a pickup sheet, a die attach film, and the like are attached to the back side surface 50a of the workpiece. Here, in the case where the adhesive layer 12 is composed of an energy ray-curable adhesive composition, the energy ray is irradiated to the adhesive layer 12 to be hardened, whereby the adhesion of the surface protective sheet can be reduced, so that it can be easily removed. Surface protection sheet.

Then, after the surface protection sheet is removed, the workpiece can be divided into wafers by applying an external force to other sheets such as a pickup sheet, a die attach film, or the like.

In this case, examples of the energy ray include ultraviolet rays, electron beams, and the like, and ultraviolet rays are preferable.

The exposure amount in the case where the energy ray is ultraviolet ray is preferably from 100 to 1,000 mJ/cm ² , more preferably from 300 to 700 mJ/cm ² .

Further, when the electron beam is used as the energy line, the acceleration voltage is preferably 10 to 1000 kV, and the irradiation amount is preferably selected within the range of 10 to 1000 krad.

[Examples]

The weight average molecular weight (Mw) of the component used in the following production examples and the compound produced is a value measured by the method described below.

<weight average molecular weight (Mw)>

Using a gel permeation chromatography apparatus (manufactured by TOSOH Co., Ltd., product name "HLC-8020"), the measurement was carried out under the following conditions, and the values measured by standard polystyrene conversion were used.

(measurement conditions)

‧ Pipe column: "TSK guard column HXL-H" "TSK gel GMHXL (×2)" "TSK gel G2000HXL" (all of which are manufactured by TOSOH Co., Ltd.)

‧column temperature: 40 ° C

‧Expanding solvent: tetrahydrofuran

‧Flow rate: 1.0mL/min

Manufacturing example 1 [Preparation of Solution of Acrylic Copolymer (1) and Adhesive Composition (1)]

52 parts by mass of butyl acrylate, 20 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate were solution-polymerized in an ethyl acetate solvent to obtain a non-energy-curable acrylic copolymer. Methyl propylene oxide B in an amount such that the number of isocyanate groups is 0.9 equivalents with respect to the total number of hydroxyl groups of the obtained acrylic copolymer The isocyanate is added to a solution containing the acrylic copolymer and reacted to form an energy ray-curable acrylic copolymer (1) (Mw: 1,000,000) having an energy ray-polymerizable group in a side chain.

Then, with respect to 100 parts by mass of the solid content of the acrylic copolymer (1), 0.5 parts by mass of an isocyanate-based crosslinking agent (manufactured by Polyurethane Co., Ltd., trade name "Coronate L") (solid content) And an energy ray-curable adhesive composition prepared by using 0.57 parts by mass (solid content ratio) of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Corporation, trade name "Irgacure 184") as a photopolymerization initiator ( 1) The solution.

Manufacturing Example 2 [Preparation of Solution of Acrylic Copolymer (2) and Adhesive Composition (2)]

In an ethyl acetate solvent, 84 parts by mass of butyl acrylate, 8 parts by mass of methyl methacrylate, 3 parts by mass of acrylic acid, and 5 parts by mass of 2-hydroxyethyl acrylate were solution-polymerized to form a non-energy curing type acrylic acid. Copolymer (2) (Mw: 800,000).

Then, with respect to 100 parts by mass of the solid content of the acrylic copolymer (2), 80 parts by mass of the urethane acrylate oligomer (Mw: 5,000) doped with the energy ray-curable compound (solid content ratio) And an isocyanate-based crosslinking agent (manufactured by Japan Polyurethane Co., Ltd., trade name "Coronate L"), 1.0 part by mass (solid content ratio), and 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator (available from BASF Corporation, trade name "Irgacure 184") 0.57 parts by mass (solid content ratio), and a solution of the energy ray-curable adhesive composition (2) was prepared.

Manufacturing Example 3 [Preparation of Solution of Acrylic Copolymer (3) and Adhesive Composition (3)]

85 parts by mass of 2-ethylhexyl acrylate and 15 parts by mass of 2-hydroxyethyl acrylate were solution-polymerized in an ethyl acetate solvent to obtain a non-energy-curable acrylic copolymer. The methacryloyloxyethyl isocyanate in an amount of 0.9 equivalents based on the total number of hydroxyl groups of the obtained acrylic copolymer is added to a solution containing the acrylic copolymer to cause reaction. An energy ray-curable acrylic copolymer (3) having an energy ray-polymerizable group in the side chain (Mw: 1,000,000).

Then, an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate L") 1.0 part by mass (solid content) is added to the acrylic copolymer (3) in an amount of 100 parts by mass based on the solid content of the acrylic copolymer (3). And an energy ray-curable adhesive composition prepared by using 0.57 parts by mass (solid content ratio) of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Corporation, trade name "Irgacure 184") as a photopolymerization initiator ( 3) The solution.

Manufacturing Example 4 [Preparation of Solution of Acrylic Copolymer (4) and Adhesive Composition (4)]

In an ethyl acetate solvent, 84 parts by mass of butyl acrylate, 8 parts by mass of methyl methacrylate, 3 parts by mass of acrylic acid, and 5 parts by mass of 2-hydroxyethyl acrylate were solution-polymerized to form a non-energy curing type acrylic acid. Copolymer (4) (Mw: 800,000).

Then, an isocyanate crosslinking agent which is a crosslinking agent is blended with respect to 100 parts by mass of the solid content of the acrylic copolymer (4) (Japan) A solution of the adhesive composition (4) was prepared by using 10 parts by mass (solid content ratio) manufactured by Polyurethane Co., Ltd. under the trade name "Coronate L".

Examples 1 to 9 and Comparative Examples 1 to 6

The adhesive composition prepared in any one of Production Examples 1 to 4 shown in Table 1 was applied to a PET film subjected to polyfluorination stripping treatment so that the thickness after drying was the value shown in Table 1. The peeling surface of the product manufactured by Lintec Co., Ltd., trade name "SP-PET381031" was dried at 100 ° C for 1 minute to form an adhesive layer. Then, after bonding the adhesive layer and the substrate shown in Table 1, the PET film was removed to prepare a surface protective sheet.

The base materials used in the examples and comparative examples are as follows.

‧Multilayer substrate A: a multilayer resin film containing only LDPE (low density polyethylene) / PET (polyethylene terephthalate) / LDPE = 27.5 μm / 25.0 μm / 27.5 μm including only a total thickness of 80 μm Substrate.

‧Multilayer substrate B: A multi-layer resin film comprising a total thickness of 105 μm of LDPE/PET/LDPE=27.5 μm/50.0 μm/27.5 μm.

‧ Single-layer base material C: A single-layer resin film containing a 25 μm PET film (manufactured by Mitsubishi Plastics Co., Ltd., trade name "Diafoil T100-25").

‧ Single-layer base material D: A single-layer resin film containing a 75 μm PET film (manufactured by Toray Co., Ltd., trade name "Lumirror # 75T60").

‧ Single layer substrate E: A single layer resin film comprising a 80 μm PBT (polybutylene terephthalate) film.

‧ Substrate F with adhesive layer: Resin with easy-to-attach layer containing PET/PSA (non-energy curing type acrylic adhesive (second adhesive layer)) = 25 μm/5 μm total thickness 30 μm film.

‧ Substrate G with easy-to-adhere layer: Contains PET/Easy-bonding layer (bonding layer added by a polyethylene-based cross-linking agent to a polyester-based resin solution containing acrylate-modified polyester as a main component (Anchor coat) A layer formed of a composition) = 25 μm / 2 μm, a total thickness of 27 μm, and a resin film with an easy-to-attach layer.

‧ Single-layer substrate H: A single-layer resin film comprising a 105 μm urethane acrylate cured film.

The physical properties of the substrate and the adhesive layer constituting the surface protective sheet produced in the examples and the comparative examples were measured by the following methods. The measurement results are shown in Table 1.

<Measurement of Young's Modulus of Substrate>

The test speed was selected to be 200 mm/min, and the Young's modulus of the above substrates A to G was measured in accordance with JIS K-7127 (1999).

<Measurement of storage modulus of adhesive layer>

The adhesive used in the examples and the comparative examples was measured by a torsional shear method using a viscoelasticity measuring apparatus (manufactured by Rheometrics Co., Ltd., device name "DYNAMIC ANALYZER RDAII") at 23 ° C and 50 ° C in an environment of 1 Hz. The storage modulus G' of a sample having a diameter of 8 mm × a thickness of 3 mm obtained by a single layer of the adhesive layer formed by the composition solution.

<Thickness of Substrate and Adhesive Layer>

The thickness of the substrate (including the resin film constituting the substrate, the second adhesive layer, and the easy-adhesion layer) is measured in accordance with JIS K7130 using a constant-pressure thickness measuring device (product name "PG-02" manufactured by Teclock Corporation). .

Further, in the present embodiment, the thickness of the surface protective sheet to which the PET film subjected to the polyfluorene stripping treatment is attached is measured for the thickness of the adhesive layer, and the substrate is subtracted from the thickness thereof and subjected to polyoxylization. The value of the thickness of the peeled PET film.

Further, the thickness of the substrate F with the adhesive layer was measured by measuring the thickness of the PET film subjected to the polyoxynitride stripping treatment on the adhesive layer, and subtracting the polyether oxide stripping treatment. The thickness of the PET film.

Further, the performance evaluation of the case where the surface protective sheets produced in the examples and the comparative examples were used for the semiconductor processing step was carried out in the following manner. The evaluation results are shown in Table 1.

<Evaluation of the presence or absence of sewage infiltration>

The examples and comparative examples were carried out using a tape laminator (manufactured by Lintec Co., Ltd., device name "RAD-3510F/12") at a normal temperature (25 ° C) and a table heated to 50 ° C. The produced surface protective sheet was laminated on a circuit surface of a wafer having a patterned circuit surface having a diameter of 12 Å and a thickness of 730 μm.

After that, a Stealth laser irradiation device (manufactured by Tokyo Seimitsu Co., Ltd., device name "ML300PlusWH") was used, and a hidden laser was irradiated from the back side opposite to the wafer circuit forming surface to form a modified inside the wafer. Quality area. Then, Polish Grinder (manufactured by Tokyo Seimitsu Co., Ltd., device name "PG3000RM") was used to polish the wafer from the back surface of the wafer while being exposed to ultrapure water, and the wafer was diced to obtain a wafer having a thickness of 20 μm.

The evaluation between the circuit surface of the sewage and the surface protection sheet is observed by visual observation of the entire surface of the polished wafer surface, and is evaluated according to the following criteria according to the frequency of infiltration of the sewage.

A: No part of the infiltration of sewage occurred.

B: Although a small portion of the infiltration of the sewage was observed, no part of the sewage was observed to penetrate into the circuit surface.

C: The part in which the sewage penetrated into the circuit surface was observed.

<Evaluation of peelability>

For the singulated wafer obtained in the above-mentioned evaluation of the infiltration of sewage, the mercury circuit lamp embedded in the fully expandable expander MAE300 is used for UV irradiation of the surface of the wafer to which the surface protective sheet is attached, and transferred to the pickup. The sheet is peeled off from the surface protection sheet.

The surface of the wafer after the surface protective sheet was peeled off was observed by using a visual and digital microscope (manufactured by Keyence Corporation, device name "VHX-1000"), and the peeling property was evaluated according to the following criteria.

In addition, this test is only conducted for those who have obtained good results (A or B) for the above-mentioned assessment of the presence or absence of sewage infiltration.

A: No adhesion of the adhesive to the surface of the wafer was observed in any of the visual and digital microscope observations.

B: In the observation of either or both of the visual and digital microscopes, it was observed that the adhesive adhered to the surface of the wafer.

When the surface protection sheets of Examples 1 to 9 were heat-applied to the wafer, the result of suppressing the penetration of the sewage into the circuit surface was obtained.

On the other hand, in the case where the surface protective sheets of Comparative Examples 1 to 6 were heat-applied to the wafer, the portion in which the sewage penetrated into the circuit surface was observed.

[Possibility of industrial use]

The surface protection sheet of the present invention is applied to the back grinding step of the workpiece to prevent the water from penetrating into the protected surface of the workpiece from the gap formed by the cutting of the workpiece, thereby preventing contamination of the protected surface of the workpiece.

Therefore, it is suitable as a surface protection sheet for a workpiece for a wafer manufacturing method in which a wafer is formed by polishing a back surface of a workpiece by forming a modified region in a workpiece such as a semiconductor wafer by a stealth dicing (registered trademark).

1a, 1b‧‧‧ surface protection film

11‧‧‧Substrate

12‧‧‧Adhesive layer

13‧‧‧ peeling material

Claims (7)

A surface protection sheet having an adhesive layer on a substrate and in a grinding step of a workpiece having a modified region formed therein, wherein the modified region is cracked by grinding of the workpiece in the workpiece When the gap is formed, the surface protective sheet attached to the workpiece meets the following requirements (a) to (d): (a) the Young's modulus of the substrate is 450 MPa or more; (b) the adhesive layer is at 25 ° C The storage modulus is 0.10 MPa or more; (c) the storage modulus of the adhesive layer at 50 ° C is 0.20 MPa or less; (d) the thickness of the adhesive layer is 30 μm or more. The surface protection sheet of claim 1, wherein the adhesive layer comprises an energy ray-curable adhesive composition. The surface protection sheet of claim 1 or 2, wherein the substrate has a thickness of 5 to 250 μm. The surface protection sheet of claim 1 or 2, wherein the substrate comprises a polyester film as a resin film. The surface protection sheet according to claim 1 or 2, wherein the substrate has a resin film; and a second adhesive layer comprising a non-energy hardening type adhesive composition having a thickness of 10 μm or less laminated on the resin film or An easy-to-layer layer having a thickness of 10 μm or less. The surface protection sheet of claim 1, wherein the surface protection sheet is attached to a surface of the workpiece on which the unevenness is formed. The surface protection sheet of claim 1 or 6, wherein the surface protection sheet is attached to a workpiece heated to 40 to 80 °C.