JPWO2018181240A1 - Adhesive tape for protecting semiconductor wafer surface and method for processing semiconductor wafer - Google Patents

Abstract

A pressure-sensitive adhesive tape for protecting a semiconductor wafer surface, which is used by heating and bonding at a temperature of 40 ° C. to 90 ° C. on a surface of a semiconductor wafer having an unevenness of 20 μm or more, wherein the pressure-sensitive adhesive tape for protecting a semiconductor wafer surface comprises a substrate A film, a pressure-sensitive adhesive layer, and an intermediate resin layer between the base film and the pressure-sensitive adhesive layer, wherein the thickness of the intermediate resin layer is equal to or greater than the unevenness difference, and constitutes the intermediate resin layer. Adhesive for protecting the surface of a semiconductor wafer, wherein the melting point or the Vicat softening point of the resin to be formed is 40 ° C. to 90 ° C., and the melt mass flow rate of the resin constituting the intermediate resin layer is 10 g / min to 100 g / min. Of processing a semiconductor wafer using the method.

Description

  The present invention relates to an adhesive tape for protecting a semiconductor wafer surface and a method for processing a semiconductor wafer.

A semiconductor package is manufactured by slicing a high-purity silicon single crystal or the like into a semiconductor wafer and then forming an integrated circuit on the wafer surface by ion implantation, etching, or the like. By grinding and polishing the back surface of the semiconductor wafer on which the integrated circuit is formed, the semiconductor wafer is processed to a desired thickness. At this time, in order to protect the integrated circuit formed on the surface of the semiconductor wafer, an adhesive tape for protecting the surface of the semiconductor wafer (hereinafter, also simply referred to as “surface protection tape”) is used.
After the backside grinding is completed, the backside ground semiconductor wafer is stored in a wafer cassette, transported to a dicing process, and processed into semiconductor chips.

Conventionally, it has been required to reduce the thickness of the semiconductor wafer to about 200 to 400 μm by back grinding or the like. However, with recent advances in high-density mounting technology, it has become necessary to reduce the size of semiconductor chips, and accordingly, semiconductor wafers have become thinner. Depending on the type of semiconductor chip, it is necessary to reduce the thickness of the semiconductor wafer to about 100 μm. On the other hand, in order to increase the number of semiconductor chips that can be manufactured by one processing, the diameter of the original semiconductor wafer tends to be increased. Until now, semiconductor wafers having a diameter of 5 inches or 6 inches have been the mainstream, but in recent years, processing of converting semiconductor wafers having a diameter of 8 to 12 inches into semiconductor chips has become the mainstream.
The trend of increasing the diameter of a semiconductor wafer at the same time as the thinning is remarkable particularly in the field of flash memories in which a NAND type or NOR type exists, and in the field of a volatile memory such as a DRAM. For example, it is not uncommon to grind a semiconductor wafer having a diameter of 12 inches to a thickness of 150 μm or less.

  In addition, wafers used for flip-chip mounting using semiconductor wafers with electrodes in consideration of impact resistance, etc., especially with the recent spread of smartphones and the improvement of mobile phone performance and miniaturization and performance improvement of music players Also, the demand for thinning is increasing. Also for semiconductor wafers with bumps, it has become necessary to grind the semiconductor wafer portion to a thickness of 100 μm or less. The bumps for flip-chip connection have been increased in density to improve transfer speed, and the height of the bumps (projection height from the surface of the semiconductor wafer) has been reduced. Is getting shorter. In recent years, flip-chip connection has also been implemented for DRAMs, and therefore, thinning of wafers has been accelerated.

  Flip-chip mounting has attracted attention as a method for mounting a semiconductor element with a minimum area in recent years for miniaturization and higher density of electronic devices. A bump is formed on an electrode of a semiconductor element used for flip-chip mounting, and electrically connects the bump to a wiring on a circuit board. As the composition of these bumps, solder or gold is mainly used. These solder bumps and gold bumps are formed on exposed aluminum terminals connected to the internal wiring of the chip by vapor deposition or plating.

  However, semiconductor wafers with bumps have large irregularities on the surface, making it difficult to process thin films. Grinding the back surface using a normal surface protection tape can cause cracks in the semiconductor wafer or increase the thickness accuracy of the semiconductor wafer. Or worse. Therefore, the grinding of the semiconductor wafer with bumps is performed using a specially designed surface protection tape (for example, see Patent Document 1).

  However, since these surface protection tapes sufficiently absorb the bumps to ensure the grinding property, it is very difficult to achieve compatibility with the peelability. The finished thickness of the chip mounted by the flip chip has a thickness of 200 μm or more and has a certain thickness, and since the rigidity is maintained, the chip can be peeled off. However, recently, since the finished thickness of the semiconductor wafer has become thinner and the bump density has been increased, the surface protective tape has caused problems such as difficulty in peeling and adhesive residue. Conversely, if the releasability is ensured, the adhesion becomes insufficient, causing seapage (for example, intrusion of dust or grinding water) during backside grinding.

  On the other hand, the bump height of the bumped semiconductor wafer used for the wafer level package is still high, and bumps having a height of 250 μm or more are also mounted. The wafer level package does not require chips to be stacked, so it is not extremely thin, such as 50 μm or less, unlike memory-based semiconductor wafers. The problem of cracking of the semiconductor wafer easily occurs with the ground thickness.

  A surface protection tape dedicated to such a semiconductor wafer has been proposed (see Patent Documents 2 to 4). Patent Document 2 describes an adhesive tape for protecting the surface of a semiconductor wafer that can be firmly adhered to a semiconductor wafer when processing the semiconductor wafer and that can be peeled at the time of peeling without breakage of the semiconductor wafer or adhesive residue. This surface protection tape has a radiation-curable pressure-sensitive adhesive layer having a layer thickness and a shrinkage value within specific ranges on a base film. Further, Patent Document 3 discloses a surface protection adhesive tape used for grinding the back surface of a bump wafer having a high bump height, which prevents wafer breakage and does not cause seapage even when the wafer is ground. The remaining suppressed adhesive tape for semiconductor wafer surface protection is disclosed. This surface protection tape has a specific tack force and layer thickness. Further, Patent Document 4 discloses that when grinding the back surface of a wafer to a height difference of not more than the height of the unevenness formed on the wafer surface, protection of the unevenness of the wafer surface and prevention of intrusion of grinding debris and grinding water into the wafer surface. And a method of bonding a pressure-sensitive adhesive sheet for protecting a semiconductor wafer, which can prevent breakage of a wafer after grinding. The surface protective sheet used in this method has an intermediate layer and a pressure-sensitive adhesive layer in which the loss tangent at 50 ° C to 100 ° C is within a specific range.

JP 2001-203255 A Japanese Patent No. 5242830 Japanese Patent No. 5117630 JP 2010-258426 A

  With the surface protection tape described in Patent Document 2, breakage of the semiconductor wafer and adhesive residue can be suppressed to a certain extent. Further, the surface protective tape described in Patent Document 3 has good releasability. However, in order to apply a higher bump to a semiconductor wafer having a narrower pitch, the surface protection tape described in Patent Literature 2 has room for further improving peelability or adhesive residue. Further, the surface protective tape described in Patent Document 3 has room for further improving adhesion, suppressing seapage, and improving adhesive residue.

  Since the surface protection tape used in the method described in Patent Document 4 has very good followability, when the surface protection tape follows a bump having a height of 250 μm or more, the tape is deformed into an uneven shape, and the tape is sucked and conveyed. In some cases, a semiconductor wafer being transported in a processing apparatus falls and is damaged.

  The present invention has been made in view of the above-described problems, and when firmly bonded to a semiconductor wafer during semiconductor wafer processing, suppresses seapage, transport errors in a processing apparatus, and damage to the semiconductor wafer. An object of the present invention is to provide a pressure-sensitive adhesive tape for protecting a semiconductor wafer surface and a method for processing a semiconductor wafer using the same.

  The present inventors have conducted intensive studies in order to solve the above-described problems, and as a result, in a base film, an adhesive tape for protecting a semiconductor wafer surface having an intermediate resin layer and an adhesive layer, a resin constituting the intermediate resin layer. The melting point or the Vicat softening point and the melt mass flow rate (MFR) of each are within a specific range, and the surface protection tape is heated and bonded at a specific temperature to the surface of a semiconductor wafer having a specific unevenness. The tape can be firmly adhered to the circuit surface of the semiconductor wafer, seapage during semiconductor wafer processing, transport errors in processing equipment, and semiconductor wafer damage can be suppressed. And furthermore, it has been found that warpage in a state of being bonded to the surface of the semiconductor wafer can be suppressed. The present invention has been made based on this finding.

That is, the above problem was solved by the following means.
<1>
An adhesive tape for protecting a semiconductor wafer surface, which is used by heating and bonding at a temperature of 40 ° C. to 90 ° C. on a surface of a semiconductor wafer having an unevenness of 20 μm or more,
The semiconductor wafer surface protection adhesive tape has a base film, an adhesive layer, and an intermediate resin layer between the base film and the adhesive layer,
The thickness of the intermediate resin layer is equal to or greater than the unevenness difference, the melting point or the Vicat softening point of the resin constituting the intermediate resin layer is 40 ° C. to 90 ° C., and the melt mass flow rate of the resin constituting the intermediate resin layer Is 10 g / min to 100 g / min.
<2>
The adhesive strength of the pressure-sensitive adhesive layer after irradiating ultraviolet rays to the SUS280 polished surface at 23 ° C. is 0.5 N / 25 mm or more and 5.0 N / 25 mm or less, and the adhesive force to the SUS280 polished surface at 50 ° C. is 0.3 N. The pressure-sensitive adhesive tape for protecting the surface of a semiconductor wafer according to <1>, which is not less than / 25 mm and not more than 7.0 N / 25 mm.

<3>
<1> or <2>, wherein the ratio of the thickness of the base film to the thickness of the intermediate resin layer is such that the thickness of the base film: the thickness of the intermediate resin layer = 0.5: 9.5 to 7: 3. 4. The adhesive tape for protecting a semiconductor wafer surface according to item 1.
<4>
Any of <1> to <3>, wherein the resin constituting the intermediate resin layer is at least one of an ethylene-methyl acrylate copolymer resin, an ethylene-ethyl acrylate copolymer resin, and an ethylene-butyl acrylate copolymer resin. Item 2. The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to Item 1.
<5>
The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to any one of <1> to <4>, wherein the constituent material of the base film has a melting point of 90 ° C to 150 ° C.
<6>
The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to any one of <1> to <5>, wherein the thickness of the intermediate resin layer is 100 μm to 400 μm.
<7>
The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to any one of <1> to <6>, wherein the pressure-sensitive adhesive layer has a thickness of 5 μm to 40 μm.
<8>
The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to any one of <1> to <7>, wherein the thickness of the base film is 25 µm to 100 µm.

<9>
A semiconductor wafer processing method that includes bonding a semiconductor wafer surface protection adhesive tape to a surface of a semiconductor wafer having an unevenness of 20 μm or more under heating at 40 ° C. to 90 ° C. and grinding the back surface of the semiconductor wafer. So,
The semiconductor wafer surface protection adhesive tape has a base film, an adhesive layer, and an intermediate resin layer between the base film and the adhesive layer,
The thickness of the intermediate resin layer is equal to or greater than the unevenness difference, the melting point or the Vicat softening point of the resin constituting the intermediate resin layer is 40 ° C. to 90 ° C., and the melt mass flow rate of the resin constituting the intermediate resin layer is Is from 10 g / min to 100 g / min.

In the description of the present invention, the surface of the semiconductor wafer means a surface of the semiconductor wafer having irregularities, that is, a surface on which an integrated circuit is formed. The surface opposite to the front surface is referred to as a back surface.
In the description of the present invention, the unevenness difference means a distance from the highest part of the convex parts to the wafer surface or a distance from the deepest part of the concave parts to the semiconductor wafer surface. For example, in the case where a metal electrode (bump) is formed on a semiconductor wafer, the highest part is the top of the highest bump, and the distance from that to the semiconductor wafer surface, that is, the height of the bump is different from the unevenness. It is. Alternatively, when a scribe line (dicing line) is formed on a semiconductor wafer, the deepest part is the deepest position of the scribe line, and the distance from the scribe line to the surface of the semiconductor wafer is referred to as an unevenness difference.
In the description of the present invention, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit and an upper limit.

  ADVANTAGE OF THE INVENTION The adhesive tape for semiconductor wafer surface protection of this invention reduces generation | occurrence | production of a seapage by firmly adhering to a semiconductor wafer at the time of semiconductor wafer processing, and also suppresses the transport error in a processing apparatus or a semiconductor wafer damage. When peeled, adhesive residue is less likely to occur. Furthermore, the adhesive tape for protecting a semiconductor wafer surface of the present invention can suppress warpage in a state of being bonded to the semiconductor wafer surface. Further, according to the method for processing a semiconductor wafer of the present invention, it is possible to obtain a thin-film semiconductor wafer having high bumps at a narrow pitch by using the pressure-sensitive adhesive tape for protecting the surface of the semiconductor wafer.

It is a schematic outline sectional view of the pressure sensitive adhesive tape for wafer surface protection of the present invention.

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

[Adhesive tape for semiconductor wafer surface protection]
The adhesive tape for protecting a semiconductor wafer surface according to the present invention is a pressure-sensitive adhesive tape for protecting a semiconductor wafer surface which is heated and bonded to a surface of a semiconductor wafer having an unevenness of 20 μm or more at 40 ° C. to 90 ° C. The pressure-sensitive adhesive tape for protecting a wafer surface has a base film and a pressure-sensitive adhesive layer, and further has at least an intermediate resin layer between the base film and the pressure-sensitive adhesive layer. The thickness of the intermediate resin layer is equal to or greater than the difference between the irregularities. Further, the melting point or the Vicat softening point of the resin constituting the intermediate resin layer is from 40 ° C. to 90 ° C., and the melt mass flow rate of the intermediate resin layer is from 10 g / min to 100 g / min.
The pressure-sensitive adhesive layer is not particularly limited, but is preferably a radiation-curable pressure-sensitive adhesive layer. The term “radiation-curable pressure-sensitive adhesive layer” refers to radiation [for example, light rays such as ultraviolet rays (including laser beams), and electron beams. [Ionizing radiation]]. Irradiation radiation is preferably ultraviolet light.

<Base film>
The substrate film used for the pressure-sensitive adhesive tape for protecting a semiconductor wafer surface of the present invention is not particularly limited. In the pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to the present invention, the melting point of the material constituting the base film is preferably in the range of 90 ° C to 150 ° C, more preferably in the range of 100 ° C to 140 ° C, and in the range of 110 ° C to 130 ° C. Is more preferred. When the melting point of the base film is in the above range, it is possible to prevent fusion to a bonding roller or a chuck table in a step of bonding the surface protection tape, and to sufficiently bond the semiconductor wafer having irregularities of 20 μm or more. Can be. Also, when laminating a dicing die bonding integrated film (DDF), the DDF can be laminated while preventing fusion to the chuck table. The adhesive tape for protecting the surface of a semiconductor wafer of the present invention improves the fluidity of the intermediate resin layer by applying heat to the intermediate resin layer, and secures sufficient adhesion to a semiconductor wafer having an unevenness of 20 μm or more. Therefore, the heating and bonding are performed under a sufficiently high temperature of 40 ° C to 90 ° C. Therefore, if the melting point of the material constituting the base film is too low, the back surface of the base film may be melted and fused with the bonding roller or the chuck table. When the base film is made of a non-crystalline resin such as styrene, the Vicat softening point serves as an index because there is no melting point. That is, the Vicat softening point is preferably in the range of the above melting point. If the Vicat softening point is too high, fluidity appears on the back surface of the base material (the surface opposite to the surface in contact with the intermediate resin layer), and there is a possibility of entering the porous portion of the chuck table.

The base film used for the pressure-sensitive adhesive tape for protecting a semiconductor wafer surface of the present invention is preferably made of a resin. As such a resin, plastic, rubber, and the like that are generally used in the technical field to which the present invention belongs can be used. . For example, polyolefin resins (for example, polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene A resin comprising a homopolymer or a copolymer of a monomer containing an ethylenically unsaturated group such as a methyl acrylate copolymer, an ethylene-acrylic acid copolymer or an ionomer), a polyester resin (for example, polyethylene terephthalate or polyethylene naphthalene); Phthalate resin), polycarbonate resin, polyurethane resin, engineering plastic (for example, polymethyl methacrylate), synthetic rubbers (for example, styrene-ethylene-butene or pentene copolymer), thermoplastic elastomer (E.g., a polyamide - polyol copolymer). The substrate film used for the surface protection tape of the present invention may be a film composed of one of the above resins alone or a film combining two or more types. Further, the substrate film used for the surface protection tape of the present invention may be a single layer or a multilayer film. In addition, it is preferable that the melting point of the material constituting the outermost layer on the opposite side of the intermediate resin layer be in the above range in the multilayer substrate film.
In the surface protection tape of the present invention, the base film is preferably a film made of a polyester resin or a polyolefin resin.

  The thickness of the base film is preferably 25 μm or more, and more preferably 50 μm or more, in consideration of the balance between the warp correcting power of the semiconductor wafer and the releasability of the surface protective tape, cost and manufacturing suitability. The upper limit is preferably 200 μm or less, more preferably 150 μm or less, and particularly preferably 100 μm or less. When the thickness of the base film is in the above range, even when the semiconductor wafer is thinned to a thickness of 50 μm or less, the grinding can be performed while suppressing the transport error, and the peelability of the surface protection tape can be improved. In addition, “when the semiconductor wafer is thin-film ground to 50 μm or less” means that, in the case of a semiconductor wafer having bumps, the back surface is ground until the thickness of the semiconductor wafer itself, excluding bumps, becomes 50 μm or less. In the case of a semiconductor wafer on which scribe lines are formed, it means the distance from the above-described deepest portion to the back surface.

<Intermediate resin layer>
The adhesive tape for protecting a semiconductor wafer surface according to the present invention requires an intermediate resin layer. The intermediate resin layer is melted by heating and bonding the surface protection tape to the semiconductor wafer surface at a temperature of 40 to 90 ° C., and the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer are applied to the surface shape of the semiconductor wafer having the unevenness of 20 μm or more. The shape of the intermediate resin layer follows. Further, since cooling is performed after the bonding, the surface protection tape is fixed in a state where the pressure-sensitive adhesive layer is in close contact with the surface of the semiconductor wafer, so that dust intrusion and the like can be suppressed. The melting point or the Vicat softening point of the resin constituting the intermediate resin layer used in the surface protection tape of the present invention is in the range of 40 ° C to 90 ° C, and more preferably in the range of 60 ° C to 80 ° C. Since it is necessary to heat-bond the surface protection tape in the range of 40 ° C. to 90 ° C. and adhere the pressure-sensitive adhesive layer to the surface of the semiconductor wafer, it is necessary that the tensile elastic modulus of the intermediate resin layer greatly changes in this temperature range. is there. That is, the temperature is normal when grinding the semiconductor wafer, and if the resin flows at this temperature, the thickness accuracy at the time of grinding is extremely deteriorated, so that high elasticity is preferable. On the other hand, in order to sufficiently follow the surface of the semiconductor wafer at the time of heating and bonding, the intermediate resin layer is required to have contradictory performances since it must have low elasticity. In order to realize the contradictory performance, the melting point or the Vicat softening point, which greatly affects the tensile modulus and the fluidity, needs to be 40 to 90 ° C. The melting point and the Vicat softening point are measured by the methods described in the examples. In the present invention, it is also preferable that both the melting point and the Vicat softening point of the intermediate resin layer are 40 to 90 ° C.
When the melting point and the Vicat softening point of the resin constituting the intermediate resin layer are less than 40 ° C., it is difficult to mold, and the thickness accuracy is deteriorated. That is, the thickness of the intermediate resin layer becomes uneven. On the other hand, when the melting point and the Vicat softening point of the resin constituting the intermediate resin layer exceed 90 ° C., even if they are heated and bonded under the conditions of 40 to 90 ° C., they do not sufficiently follow the shape of the surface of the semiconductor wafer, Dust penetration and wafer cracking are likely to occur.

The resin constituting the intermediate resin layer used in the surface protective tape of the present invention has a melting point or Vicat softening point of 40 to 90 ° C, and a melt mass flow rate (MFR) of 10 g / min to 100 g / min. The intermediate resin layer having a melting point or a Vicat softening point within the above range, as described above, when the surface protection tape is bonded to a semiconductor wafer under the conditions of 40 to 90 ° C., the intermediate resin layer has a shape relative to the surface shape of the semiconductor wafer. And the shape of the pressure-sensitive adhesive layer follows. As a result, the pressure-sensitive adhesive layer sufficiently adheres to the semiconductor wafer surface. However, if the melting point or the Vicat softening point of the resin constituting the intermediate resin layer is only within the above range, if the unevenness of the semiconductor wafer becomes 250 μm or more, the surface protection tape itself is deformed into an uneven shape, which causes a transport error. . By setting the MFR in the range of 10 g / min to 100 g / min, an appropriate fluidity is generated in the intermediate resin layer at the time of heating and bonding, and the surface protection tape deformed by following irregularities can be returned to a flat state. As a result, it is possible to prevent a transport error and damage due to falling of the semiconductor wafer. If the melt mass flow rate (MFR) of the intermediate resin layer is less than 10 g / min, the fluidity is insufficient and the surface protection tape itself is processed in a deformed state, so that a transport error or breakage of the semiconductor wafer occurs. Resulting in. On the other hand, when the melt mass flow rate (MFR) of the resin constituting the intermediate resin layer exceeds 100 g / min, it becomes difficult to form a film while maintaining the thickness accuracy (thickness uniformity) as a substrate. Further, the thickness accuracy of the semiconductor wafer after the grinding is also deteriorated. The surface protection tape of the present invention has the melting point or the Vicat softening point of the resin constituting the intermediate resin layer within the above range, and further, the MFR in the range of 10 g / min to 100 g / min. The present invention can be applied to processing of a semiconductor wafer having a difference of 250 μm or more. It is practical that the upper limit of the unevenness difference of the semiconductor wafer to which the surface protection tape of the present invention can be applied is 300 μm or less.
The MFR is measured by the method described in the examples.

Since the intermediate resin layer is not intended to adhere, it is preferably non-adhesive. Non-tacky refers to a state where there is no stickiness at room temperature.
As a resin constituting such a resin layer or resin film, for example, at least one comonomer selected from a radical polymerizable acid comonomer, an acrylate ester comonomer, a methacrylate ester comonomer and a vinyl carboxylate comonomer, and ethylene Resins consisting of an ethylene-based copolymer that is a copolymer of a resin, a resin consisting of a homopolymer or a copolymer of a monomer containing an ethylenically unsaturated group such as an ionomer, a resin consisting of polyethylene (for example, low-density polyethylene). No. These resins may be used alone or in combination of two or more in the intermediate resin layer used in the surface protection tape of the present invention. Further, the intermediate resin layer may have two or more layers.

Specific examples of the radical polymerizable acid comonomer include α, β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, and itaconic acid or anhydrides thereof, acrylic acid, methacrylic acid, crotonic acid, Examples thereof include unsaturated monocarboxylic acids such as vinyl acetic acid and pentenoic acid, and among them, maleic anhydride, acrylic acid, and methacrylic acid are preferable.
Specific examples of the acrylate comonomer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and the like, and among them, methyl acrylate, ethyl acrylate and butyl acrylate are preferable.

Specific examples of the methacrylate ester comonomer include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate, and among them, methyl methacrylate and ethyl methacrylate are preferred.
Specific examples of the carboxylic acid vinyl ester comonomer include vinyl formate, vinyl acetate, vinyl propionate, and vinyl butyrate, with vinyl acetate being preferred.

Specific examples of the ethylene-based copolymer include binary copolymers such as ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-maleic anhydride copolymer, and ethylene-acrylic acid. Examples include a methyl copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-methyl methacrylate copolymer, an ethylene-ethyl methacrylate copolymer, and an ethylene-vinyl acetate copolymer.
As the ternary copolymer, for example, ethylene-acrylic acid-methyl acrylate copolymer, ethylene-acrylic acid-ethyl acrylate copolymer, ethylene-acrylic acid-vinyl acetate copolymer, ethylene-methacrylic acid- Methyl methacrylate copolymer, ethylene-methacrylic acid-ethyl methacrylate copolymer, ethylene-methacrylic acid-vinyl acetate copolymer, ethylene-maleic anhydride-methyl acrylate copolymer, ethylene-maleic anhydride-acryl Ethyl acrylate copolymer, ethylene-maleic anhydride-methyl methacrylate copolymer, ethylene-maleic anhydride-ethyl methacrylate copolymer, ethylene-maleic anhydride-vinyl acetate copolymer are exemplified.
Further, a multi-component copolymer obtained by combining the above-mentioned comonomers may also be used.
Among the above copolymers, particularly, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer Copolymer, ethylene-maleic anhydride-methyl acrylate copolymer, ethylene-maleic anhydride-ethyl acrylate copolymer, ethylene-maleic anhydride-methyl methacrylate copolymer and ethylene-maleic anhydride-ethyl methacrylate Copolymers are preferred, and ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer and ethylene-butyl acrylate copolymer are preferred.

The proportion of the comonomer is preferably from 10% by mass to 50% by mass, more preferably from 15% by mass to 40% by mass, based on the total mass of ethylene and the comonomer used for the synthesis of the ethylene copolymer.
The intermediate resin layer may be a single layer as described above, or may be a multiple layer. From the viewpoint of manufacturability, a multilayer film is easier to form a film than a single layer. In the case of forming a multilayer, the layer on the substrate film side is preferably a resin layer or a resin film composed of low-density polyethylene or ethylene-vinyl acetate copolymer, and when forming a multilayer intermediate resin layer by extrusion. In addition, the defective rate can be reduced, and the device can be manufactured at low cost. The melting point or Vicat softening point in the case where the intermediate resin layer is a multilayer indicates the melting point or Vicat softening point of the resin constituting the layer or film in contact with the pressure-sensitive adhesive layer.
The method of laminating the resin layer or the resin film is not particularly limited as long as the accuracy of the thickness of the resin layer or the resin film or the defect that does not affect the resin layer or the resin film is affected. For example, film formation by co-extrusion or bonding with an adhesive may be mentioned.

  The ratio of the thickness of the base film to the thickness of the intermediate resin layer is such that the thickness of the base film: the thickness of the intermediate resin layer = 0.5: 9.5 to 3: 7, It is preferable from the viewpoint of the ability of the intermediate resin layer to follow the surface shape of the semiconductor wafer. The method of laminating the base film and the intermediate resin layer is not particularly limited as long as it does not affect the defects of the integrated film, and film formation by co-extrusion or bonding by an adhesive is possible.

  The thickness of the intermediate resin layer used in the surface protection tape of the present invention needs to be not less than the unevenness of the semiconductor wafer, but is preferably 100 μm to 400 μm from the viewpoint of productivity and thickness accuracy. If the thickness is smaller than the unevenness of the semiconductor wafer, the pressure-sensitive adhesive layer does not sufficiently adhere to the semiconductor wafer, so that dust intrusion and wafer cracking occur. The thickness of the intermediate resin layer used for the surface protection tape of the present invention is preferably 10 μm to 30 μm thicker than the unevenness of the semiconductor wafer. If the intermediate resin layer is too thick, the thickness accuracy of the semiconductor wafer may be deteriorated, and the manufacturing cost will increase. Further, when a bump portion of a bumped semiconductor wafer is manufactured, an error of about 10 μm occurs. Therefore, if the thickness is 10 μm in addition to the average bump height, it is possible to follow up with a margin.

<Adhesive layer>
The pressure-sensitive adhesive used in the pressure-sensitive adhesive layer of the surface protection tape of the present invention is not particularly limited, but a radiation-curable pressure-sensitive adhesive is preferable.
The radiation-curable pressure-sensitive adhesive only needs to have the property of being cured by radiation to form a three-dimensional network, and is broadly divided into 1) an ethylenically unsaturated group (an ethylenically unsaturated carbon-carbon double bond at the side chain); A pressure-sensitive adhesive comprising a base resin (polymer) having a double bond) and 2) at least two ethylene atoms per molecule with respect to a normal rubber-based or (meth) acryl-based base resin (polymer). It is classified into a low molecular weight compound having an unsaturated group (hereinafter, referred to as a radiation polymerizable low molecular weight compound) and a pressure-sensitive adhesive containing a photopolymerization initiator.
In the surface protective tape of the present invention, the above 2) is preferable.

1) Adhesive consisting of a base resin having an ethylenically unsaturated group in the side chain The adhesive having an ethylenically unsaturated group in the side chain is preferably a (meth) acrylic adhesive, and the base resin is preferably a (meth) acrylic resin. Those containing a coalesced or (meth) acrylic polymer as a main component are more preferred.
Here, “containing a (meth) acrylic polymer as a main component” means that the content of the (meth) acrylic polymer is at least 50% by mass or more in the polymer or the resin constituting the base resin, Preferably, it means 80% by mass or more (100% by mass or less).

  The (meth) acrylic polymer has an ethylenically unsaturated group in at least a side chain, and thus can be cured by irradiation with radiation. The (meth) acrylic polymer may further have a functional group such as an epoxy group or a carboxy group.

The (meth) acrylic polymer having an ethylenically unsaturated group in the side chain may be produced by any method, for example, a (meth) acrylic polymer having a functional group (α) in the side chain, It has a group having an ethylenically unsaturated group such as a (meth) acryloyl group or a (meth) acryloyloxy group, and can react with the functional group (α) in the side chain of the (meth) acrylic polymer. Those obtained by reacting with a compound having a functional group (β) are preferred.
The group having an ethylenically unsaturated group may be any group as long as it has a non-aromatic ethylenic double bond, and may be a (meth) acryloyl group, a (meth) acryloyloxy group, a (meth) acryloyl An amino group, an allyl group, a 1-propenyl group, a vinyl group (including styrene or substituted styrene) are preferable, and a (meth) acryloyl group and a (meth) acryloyloxy group are more preferable.
Examples of the functional groups (α) and (β) include a carboxy group, a hydroxyl group, an amino group, a sulfanyl group, a cyclic acid anhydride group, an epoxy group, and an isocyanate group (-N = C = O).

  Here, when one of the functional groups (α) and (β) is a carboxy group, a hydroxyl group, an amino group, a sulfanyl group, or a cyclic acid anhydride group, the other functional group Is an epoxy group or an isocyanate group. When one of the functional groups is a cyclic acid anhydride group, the other functional group includes a carboxy group, a hydroxyl group, an amino group, and a sulfanyl group. When one functional group is an epoxy group, the other functional group may be an epoxy group.

As the functional group (α), a carboxy group and a hydroxyl group are preferable, and a hydroxyl group is particularly preferable.
The (meth) acrylic polymer having a functional group (α) in the side chain is a (meth) acrylic monomer having a functional group (α), preferably a (meth) acrylic acid ester (particularly, a functional group ( having α)] as a monomer component.
The (meth) acrylic polymer having a functional group (α) in the side chain is preferably a copolymer, and the copolymer component is a (meth) acrylic acid alkyl ester, in particular, a functional group ( Preferred are alkyl (meth) acrylates in which α) or a group having an ethylenically unsaturated group is not substituted.

Examples of the (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, and hexyl (meth) acrylate. ) Acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and dodecyl (meth) acrylate, decyl (meth) acrylate hexyl acrylate.
The (meth) acrylic acid ester may be used singly or in combination of two or more kinds. It is possible to use a combination of the alcohol part having 5 or less carbon atoms and the alcohol part having 6 to 12 carbon atoms. preferable.

  In addition, since the glass transition point (Tg) becomes lower as the monomer having a larger number of carbon atoms in the alcohol portion is used, a desired glass transition point can be obtained. In addition to the glass transition point, it is also preferable to blend a low-molecular compound having a carbon-carbon double bond such as vinyl acetate, styrene, and acrylonitrile for the purpose of improving compatibility and various performances. Is preferably in the range of 5% by mass or less.

  Examples of the (meth) acrylic monomer having a functional group (α) include acrylic acid, methacrylic acid, cinnamic acid, itaconic acid, fumaric acid, phthalic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, and glycols Monoacrylates, glycol monomethacrylates, N-methylol acrylamide, N-methylol methacrylamide, allyl alcohol, N-alkylaminoethyl acrylates, N-alkylaminoethyl methacrylates, acrylamides, methacrylamides, maleic anhydride, Itaconic anhydride, fumaric anhydride, phthalic anhydride, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, part of the isocyanate group of the polyisocyanate compound is hydroxyl or Such as those urethanization with monomers like having a carboxy group and an ethylenic unsaturated group.

  Among these, acrylic acid, methacrylic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, glycidyl acrylate, glycidyl methacrylate are preferred, and acrylic acid, methacrylic acid, 2-hydroxyalkyl acrylates, and 2-hydroxyalkyl methacrylate are preferred. Are more preferable, and methacrylic acid, 2-hydroxyalkyl acrylates, and 2-hydroxyalkyl methacrylates are still more preferable.

As the functional group (β) in the compound having an ethylenically unsaturated group and a functional group (β), an isocyanate group is preferable. For example, (meth) acrylic acid having an isocyanate (—N ＝ C ＝ O) group in an alcohol part Esters, and among them, alkyl (meth) acrylate substituted with an isocyanate (-N = C = O) group is preferable. Examples of such a monomer include 2-isocyanatoethyl methacrylate and 2-isocyanatoethyl acrylate.
When the functional group (β) is other than the isocyanate group, preferred compounds include the compounds exemplified as the (meth) acrylic monomer having the functional group (α).

  The compound having an ethylenically unsaturated group and a functional group (β) may have a functional group (α) in the side chain of the polymer in addition to the (meth) acrylic polymer having the functional group (α) in the side chain, preferably By reacting with a hydroxyl group, a polymerizable group can be incorporated into the copolymer, and the adhesive strength after irradiation can be reduced.

  In the synthesis of the (meth) acrylic copolymer, ketone, ester, alcohol and aromatic solvents can be used as the organic solvent when the reaction is carried out by solution polymerization. Ethyl acetate, isopropyl alcohol, benzene methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone and the like are generally good solvents for (meth) acrylic polymers, and are preferably solvents having a boiling point of 60 to 120 ° C. As the polymerization initiator, an azobis-based radical generator such as α, α'-azobisisobutyronitrile and an organic peroxide-based radical generator such as benzoyl peroxide are usually used. At this time, a catalyst and a polymerization inhibitor can be used in combination as needed, and a (meth) acrylic copolymer having a desired molecular weight can be obtained by adjusting the polymerization temperature and the polymerization time. For adjusting the molecular weight, it is preferable to use a solvent such as mercaptan or carbon tetrachloride. This reaction is not limited to solution polymerization, and other methods such as bulk polymerization and suspension polymerization may be used.

The weight average molecular weight of the base resin (preferably (meth) acrylic copolymer) having an ethylenically unsaturated group in the side chain is preferably about 200,000 to 1,000,000.
If the weight average molecular weight is too large, the adhesive after irradiation is inflexible and brittle when irradiated with radiation, so that adhesive residue is left on the semiconductor chip surface during peeling. If the mass average molecular weight is too small, the cohesive strength before irradiation is small and the adhesive strength is weak, so that the semiconductor chip cannot be sufficiently held at the time of dicing, and chip flying may occur. In addition, curing is insufficient even after irradiation, and adhesive residue is left on the semiconductor chip surface during peeling. In order to prevent these as much as possible, the weight average molecular weight is preferably 200,000 or more.
In the description of the present invention, the mass average molecular weight is a polystyrene equivalent mass average molecular weight according to a conventional method.

  The glass transition point of the base resin having an ethylenically unsaturated group in the side chain is preferably from -70 to -10C, more preferably from -50 to -10C. If the glass transition point is too low, the flowability of the pressure-sensitive adhesive will be high, causing adhesive residue. If the glass transition point is too high, the flowability will be insufficient and it will not easily fit into the backside of the semiconductor wafer, and grinding water will be generated during grinding of the semiconductor wafer. This may cause infiltration into the wafer surface.

The acid value of the base resin having an ethylenically unsaturated group in the side chain [mg number of potassium hydroxide required to neutralize the free fatty acid present in 1 g of the base resin] is preferably 0.5 to 30, 1-20 are more preferable.
The hydroxyl value of the base resin having an ethylenically unsaturated group in the side chain [mg of potassium hydroxide required to neutralize acetic acid bonded to the hydroxyl group when 1 g of the base resin is acetylated] is 5 -100 is preferable, and 10-80 is more preferable.
By doing so, the effect of preventing adhesive residue at the time of peeling the adhesive tape for protecting the semiconductor wafer surface is further excellent.

  The acid value and the hydroxyl value are adjusted by preparing a (meth) acrylic polymer having a functional group (α) in a side chain and an ethylenically unsaturated group and having the (meth) acrylic polymer. At the stage of reacting the functional group (α) of the side chain with a compound having a functional group (β) capable of reacting, a desired compound can be prepared by leaving an unreacted functional group.

When the base resin having an ethylenically unsaturated group in the side chain is cured by irradiation, if necessary, a photopolymerization initiator, for example, isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, phenyldimethoxyacetylbenzene, Michler's ketone, Chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, benzyldimethylketal, α-hydroxycyclohexylphenyl ketone, 2-hydroxymethylphenylpropane and the like can be used.
The compounding amount of the photopolymerization initiator is preferably from 0.01 to 10 parts by mass, more preferably from 0.01 to 5 parts by mass, based on 100 parts by mass of the base resin. If the amount is too small, the reaction is insufficient. If the amount is too large, low molecular components increase to affect the contamination.

The pressure-sensitive adhesive comprising a base resin having an ethylenically unsaturated group in a side chain preferably contains a crosslinking agent.
Such a cross-linking agent may be any, but a cross-linking agent selected from the group consisting of polyisocyanates, melamine / formaldehyde resin and epoxy resin is preferable.
Among them, polyisocyanates are preferable in the surface protective tape of the present invention.

  The polyisocyanate is not particularly limited. For example, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenyl ether diisocyanate, 4,4 ′-[2,2-bis (4 -Phenoxyphenyl) propane] aromatic isocyanate such as diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate , Lysine diisocyanate, lysine triisocyanate and the like. Specifically, Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) can be used.

  Specific examples of the melamine / formaldehyde resin include Nikarac MX-45 (trade name, manufactured by Sanwa Chemical Co., Ltd.) and Melan (trade name, manufactured by Hitachi Chemical Co., Ltd.).

  As the epoxy resin, TETRAD-X (trade name, manufactured by Mitsubishi Chemical Corporation) or the like can be used.

The amount of the crosslinking agent is preferably 0.1 to 10 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the base resin.
After the application of the pressure-sensitive adhesive, the cross-linking agent allows the base resin to form a cross-linked structure, thereby improving the cohesion of the pressure-sensitive adhesive.

  If the amount of the crosslinking agent is too small, the effect of improving the cohesive strength is not sufficient, so that the pressure-sensitive adhesive has a high fluidity and causes adhesive residue. If the amount of the crosslinking agent is too large, the elastic modulus of the pressure-sensitive adhesive becomes too high, and the semiconductor wafer surface cannot be protected.

2) Pressure-sensitive adhesive containing radiation-polymerizable low-molecular-weight compound The main component of the pressure-sensitive adhesive containing a radiation-polymerizable low-molecular-weight compound is not particularly limited, and is usually chlorinated polypropylene resin or acrylic used for the pressure-sensitive adhesive. Resins ((meth) acrylic resin), polyester resins, polyurethane resins, epoxy resins, and the like can be used.

In the surface protective tape of the present invention, the base resin of the adhesive is preferably an acrylic resin ((meth) acrylic resin), which is a raw material for synthesizing the above-described base resin having an ethylenically unsaturated group in the side chain. A (meth) acrylic polymer having a functional group (α) in a side chain is particularly preferred.
As the pressure-sensitive adhesive in this case, it is preferable to prepare a pressure-sensitive adhesive by appropriately blending a photopolymerization initiator, a curing agent or a crosslinking agent, in addition to an acrylic resin as a base resin and a radiation-polymerizable low molecular weight compound.

The mass average molecular weight of the base resin of the pressure-sensitive adhesive is preferably about 200,000 to 2,000,000.
The pressure-sensitive adhesive preferably contains at least one oligomer having a mass average molecular weight of 1,000 to 20,000 in addition to the base resin. The mass average molecular weight of the oligomer is more preferably from 1,100 to 20,000, further preferably from 1,300 to 20,000, and particularly preferably from 1,500 to 10,000.

As the radiation-polymerizable low molecular weight compound, a molecule which has at least two ethylenically unsaturated groups (radiation-polymerizable carbon-carbon double bonds) in a molecule and which can be three-dimensionally reticulated by irradiation, has a functional group (β) A low molecular weight compound having at least one of them (preferably a hydroxy group) is used.
In particular, in the surface protective tape of the present invention, it is preferable that the oligomer is a radiation-polymerizable low molecular weight compound having an ethylenically unsaturated group.

  Specific examples of the radiation polymerizable low molecular weight compound include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, Such as dipentaerythritol hexa (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and oligoester (meth) acrylate (Meth) acrylate-based compounds are applicable.

In addition to the above (meth) acrylate-based compounds, urethane (meth) acrylate-based oligomers can be used as the radiation-polymerizable low molecular weight compound. The urethane (meth) acrylate oligomer includes a polyol compound such as a polyester type or a polyether type and a polyvalent isocyanate compound (for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3 -Xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4-diisocyanate, etc.), and reacting a terminal isocyanate urethane prepolymer with a hydroxy group-containing (meth) acrylate (for example, , 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, etc.) It was obtained.
One or more radiation-polymerizable low molecular weight compounds may be used in combination.

  The radiation-curable pressure-sensitive adhesive can contain a photopolymerization initiator as needed. The photopolymerization initiator is not particularly limited as long as it reacts with radiation passing through the substrate, and a usual one can be used. For example, benzophenones such as benzophenone, 4,4′-dimethylaminobenzophenone, 4,4′-diethylaminobenzophenone, and 4,4′-dichlorobenzophenone; acetophenones such as acetophenone, diethoxyacetophenone and phenyldimethoxyacetylbenzene; Anthraquinones such as ethylanthraquinone and t-butylanthraquinone, 2-chlorothioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzyl, 2,4,5-triary-imidazole dimer (rophin dimer), and acridine compounds , Acylphosphine oxides, etc., and these can be used alone or in combination of two or more.

  The addition amount of the photopolymerization initiator is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 7.5 parts by mass, and still more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the base resin. . If the addition amount of the photopolymerization initiator is too large, radiation curing occurs at multiple points and rapidly, and the radiation curing shrinkage increases. Reducing the amount of the polymerization initiator is also useful from the viewpoint of suppressing radiation curing shrinkage.

The pressure-sensitive adhesive preferably contains a curing agent or a crosslinking agent.
Examples of the curing agent or the cross-linking agent include a polyvalent isocyanate compound, a polyvalent epoxy compound, a polyvalent aziridine compound, a chelate compound and the like.

  The polyvalent isocyanate compound is not particularly limited. For example, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenyl ether diisocyanate, 4,4 ′-[2,2-bis ( 4-phenoxyphenyl) propane] aromatic isocyanate such as diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane Diisocyanate, lysine diisocyanate, lysine triisocyanate and the like. Specifically, Coronate L (trade name, manufactured by Nippon Polyurethane Industry Co., Ltd.) or the like can be used.

Examples of the polyvalent epoxy compound include an epoxy resin, and examples thereof include ethylene glycol diglycidyl ether, terephthalic acid diglycidyl ester acrylate, and anilines in which two glycidyl groups are substituted on the N atom. Further, the above-mentioned TETRAD-X can also be used.
In addition, as an aniline, N, N'-tetraglycidyl-m-phenylenediamine is mentioned.

  Polyvalent aziridine compounds include tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, tris [1- (2-methyl) -aziridinyl] phosphine oxide, hexa [1- (2- Methyl) -aziridinyl] triphosphatriazine and the like. Examples of the chelate compound include ethyl acetoacetate aluminum diisopropylate and aluminum tris (ethyl acetoacetate).

  0.1-10 mass parts is preferable with respect to 100 mass parts of base resins, 0.1-5.0 mass parts is more preferable, and the compounding quantity of a hardening | curing agent or a crosslinking agent is 0.5-4.0 mass parts. Is more preferred.

(Thickness of adhesive layer)
The thickness of the pressure-sensitive adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, and still more preferably 20 μm or more from the viewpoint of productivity. The upper limit is preferably 75 μm or less, more preferably 50 μm or less, and particularly preferably 40 μm or less. The pressure-sensitive adhesive layer may be a multilayer, and in that case, it is preferable that at least the outermost pressure-sensitive adhesive in contact with the semiconductor wafer surface is a radiation-curable pressure-sensitive adhesive.

(Characteristics of adhesive layer or adhesive)
(Content of the ethylenically unsaturated group having in the radiation-curable pressure-sensitive adhesive layer)
In the surface protective tape of the present invention, the content of the ethylenically unsaturated group (radiation-polymerizable carbon-carbon double bond) contained in the radiation-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is from 0.2 to 2.0 mmol /. g is preferred.
The content of the ethylenically unsaturated group of the radiation-curable pressure-sensitive adhesive is the sum of all ethylenically unsaturated groups of the compound having an ethylenically unsaturated group contained in the radiation-curable pressure-sensitive adhesive, It is the total number of moles of ethylenically unsaturated groups per unit g of the pressure-sensitive adhesive. The compound having an ethylenically unsaturated group is, for example, a polymer such as a base resin having an ethylenically unsaturated group in a side chain, or a radiation polymerizable low molecular weight compound.

The content of the ethylenically unsaturated group contained in the radiation-curable pressure-sensitive adhesive is preferably from 0.2 to 1.8 mmol / g, more preferably from 0.2 to 1.5 mmol / g, and from 0.5 to 1.5 mmol / g. g is more preferred.
When the pressure-sensitive adhesive layer is a multi-layer, when all the pressure-sensitive adhesive layers are regarded as one layer, the content of the ethylenically unsaturated group contained in the radiation-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is within the above range. Is preferably satisfied, and more preferably each layer satisfies the above range.

  The content of the ethylenically unsaturated group contained in the radiation-curable pressure-sensitive adhesive is determined by the number of the ethylenically unsaturated groups contained in the compound having the functional group (β) and the radiation-polymerizable low-molecular-weight compound and the blending amount of these compounds. Can be adjusted.

The content of the ethylenically unsaturated group contained in the radiation-curable pressure-sensitive adhesive can be determined from the amount of the compound used as described above or the number of the ethylenically unsaturated group contained in these compounds. In addition, the iodine value of the radiation-curable pressure-sensitive adhesive [the number of g of iodine (I ₂ ) added to the total of 100 g of the base resin and the radiation-polymerizable low molecular weight compound] was determined, and the molecular weight of I ₂ was 253.8. Can be obtained by converting this value into mmol / g.

[Adhesion after UV curing to SUS plate]
The adhesive strength of the pressure-sensitive adhesive layer of the surface protective tape of the present invention after ultraviolet irradiation is preferably 0.5 N / 25 mm or more, more preferably 0.7 N / 25 mm or more, with respect to the SUS polished surface at 23 ° C. The upper limit is preferably equal to or less than 5.0 N / 25 mm, more preferably equal to or less than 3.0 N / 25 mm, and still more preferably equal to or less than 1.5 N / 25 mm. The pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer after irradiation with ultraviolet rays is preferably 0.3 N / 25 mm or more, more preferably 0.5 N / 25 mm or more, with respect to the SUS polished surface at 50 ° C. The upper limit is preferably equal to or less than 7.0 N / 25 mm, more preferably equal to or less than 4.0 N / 25 mm, and still more preferably equal to or less than 2.5 N / 25 mm. This adhesive strength is a characteristic of the surface protection tape itself.
Here, “after irradiation with ultraviolet rays” means after the entire pressure-sensitive adhesive layer is irradiated with ultraviolet rays so as to have an integrated irradiation amount of 500 mJ / cm ² and cured.

Specifically, it can be obtained as follows.
Three test pieces each having a width of 25 mm and a length of 150 mm are collected from the surface protection tape before irradiation. A 2 kg rubber roller is reciprocated by three reciprocations on a SUS steel plate having a thickness of 1.5 mm to 2.0 mm specified in JIS G 4305 and finished with a water-resistant abrasive paper of No. 280 specified in JIS R 6253. After leaving at normal temperature (25 ° C.) for 1 hour, the adhesive layer is cured by irradiating ultraviolet rays with an integrated irradiation amount of 500 mJ / cm ² . After the pressure-sensitive adhesive layer is cured, the average value of the three points of adhesive strength is determined using a tensile tester conforming to JIS B 7721, whose measured value falls within the range of 15 to 85% of the capacity. The adhesive strength is measured at a normal temperature and a humidity of 50% by a 90 ° peeling method at a pulling speed of 50 mm / min. In this test, before the test piece is pressed against the SUS steel plate, the SUS steel plate is adjusted to a predetermined temperature (23 ° C., 50 ° C.) using a hot plate or the like. As the tensile tester, for example, a tensile tester: Twin column desktop model 5567 (trade name) manufactured by Instron can be used.

The adhesive strength after ultraviolet curing to the SUS polished surface is preferred in the present invention by appropriately adjusting the type and amount of the compound used for the adhesive, the type and amount of the additive such as a crosslinking agent, the thickness of the adhesive layer, and the like. Range.
If the adhesive strength to the SUS polished surface is too small, the curing shrinkage due to the crosslinking reaction increases, and consequently, the peeling force from an adherend having large surface irregularities such as a bump wafer increases. If the apparent adhesion to the SUS polished surface is too large, the radiation curing is insufficient and poor peeling or adhesive residue occurs.

<Release liner>
The adhesive tape for protecting a semiconductor wafer surface may have a release liner on the adhesive layer. As the release liner, a polyethylene terephthalate film subjected to a silicone release treatment is used. If necessary, a polypropylene film without silicone release treatment may be used.

<< Semiconductor wafer processing method >>
The method for processing a semiconductor wafer according to the present invention is a method for processing a semiconductor wafer using the adhesive tape for protecting a surface of a semiconductor wafer according to the present invention.
The adhesive tape for protecting a semiconductor wafer surface of the present invention may be used in any process of a semiconductor wafer. For example, a semiconductor wafer back surface grinding step, a dicing step, a dicing die bonding step and the like are preferably exemplified.

The adhesive tape for protecting a semiconductor wafer surface according to the present invention is used by being bonded to the surface of a semiconductor wafer having a difference in unevenness of 20 μm or more.
It is more preferable to apply the present invention to a semiconductor wafer having a difference in unevenness [the height of a bump (electrode) or the depth of a scribe line] of 20 to 400 μm, and more preferably to a semiconductor wafer of 50 to 250 μm.

  The arrangement density (high density) of the bumps on the surface of the semiconductor wafer is not particularly limited, but is 0.5 to 3 times or less, preferably 1 to 2 times or less the bump height (bump height). (The distance from the vertex in the vertical direction to the vertex in the height direction of the next placed bump). It is also used for a semiconductor wafer in which bumps are uniformly arranged on the entire surface.

The thickness of the semiconductor wafer is preferably from 20 to 500 μm, more preferably from 50 to 200 μm, even more preferably from 80 to 200 μm, in the thickness of the semiconductor wafer whose back surface has been ground by a processing method using a semiconductor wafer surface protection adhesive tape.
By using the pressure-sensitive adhesive tape for protecting a semiconductor wafer surface of the present invention, a thin-film semiconductor wafer can be obtained with a high yield. This method of processing a semiconductor wafer is suitable as a method of manufacturing a semiconductor wafer with electrodes that has been ground to a thickness of 50 μm or less.

  The method for processing a semiconductor wafer according to the present invention includes a step of bonding the semiconductor wafer surface protecting pressure-sensitive adhesive tape of the present invention to the surface of the semiconductor wafer, and then irradiating with radiation, in particular, ultraviolet light to peel off the semiconductor wafer surface protecting pressure-sensitive adhesive tape. It is preferable to include

Specifically, first, the pressure-sensitive adhesive tape for protecting the surface of a semiconductor wafer of the present invention is bonded to the circuit pattern surface (front surface) of the semiconductor wafer such that the pressure-sensitive adhesive layer becomes a bonding surface. Next, the side of the semiconductor wafer having no circuit pattern is ground until the semiconductor wafer has a predetermined thickness, for example, 10 to 200 μm. Then, the semiconductor wafer surface protection adhesive tape is placed on a heating suction table with the surface to which the adhesive tape is bonded facing downward, and in this state, a dicing die bonding film is applied to the ground surface of the semiconductor wafer having no circuit pattern. You may bond.
A dicing process is performed, and then a heat-sealable (heat-fusion type) or adhesive-type release tape is adhered to the back of the base film of the adhesive tape for protecting the semiconductor wafer surface, and the adhesive for protecting the semiconductor wafer surface from the semiconductor wafer. Peel off the tape.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

(Preparation of adhesive composition)
Pressure-sensitive adhesive compositions 1A to 1C were prepared as follows.

1) Preparation of PSA Composition 1A A copolymer having a weight average molecular weight of 550,000 was obtained from 78 parts by mass of 2-ethylhexyl acrylate, 17 parts by mass of 2-hydroxyethyl acrylate, and 5 parts by mass of methacrylic acid. For 100 parts by mass of this copolymer, 100 parts by mass of a urethane acrylate oligomer having pentafunctional acrylate and having a hydroxyl group as a functional group (β) and having a weight average molecular weight of 3,000, and coronate L of a polyisocyanate [trade name, Japan 5.0 parts by mass of Polyurethane Industry Co., Ltd.] and 5.0 parts by mass of SPEEDCURE BKL [trade name, manufactured by DKSH Japan] as a photopolymerization initiator were added and mixed to obtain pressure-sensitive adhesive composition 1A.

2) Preparation of pressure-sensitive adhesive composition 1B 70 parts by mass of 2-ethylhexyl acrylate, 7 parts by mass of 2-hydroxyethyl acrylate, and 23 parts by mass of methacrylic acid were polymerized in ethyl acetate, and the obtained meta having a mass average molecular weight of 1,000,000 was obtained. An acrylic polymer was obtained. 2.0 parts by mass of an epoxy-based curing agent was mixed with 100 parts by mass of the methacrylic polymer to obtain a pressure-sensitive adhesive composition B.

3) Preparation of PSA Composition 1C A copolymer having a mass average molecular weight of 600,000 was obtained from 78 parts by mass of 2-ethylhexyl acrylate, 13 parts by mass of 2-hydroxyethyl acrylate, and 9 parts by mass of methacrylic acid. Based on 100 parts by mass of this copolymer, 100 parts by mass of a urethane acrylate oligomer having trifunctional acrylate and having a hydroxy group as a functional group (β) and having a mass average molecular weight of 1,500, and 3.0 parts by mass of a polyisocyanate coronate L Then, 0.5 parts by mass of an epoxy resin, TETRAD-X (manufactured by Mitsubishi Gas Chemical Company), and 5.0 parts by mass of SPEEDCURE BKL as a photopolymerization initiator were added and mixed to obtain a pressure-sensitive adhesive composition 1C.

(Formation of base film and intermediate resin layer)
The intermediate resin layer and the base films 2A to 2G were formed as follows.

1) Preparation of Film 2A An ethylene-acrylic acid copolymer (EEA) resin (manufactured by Nippon Polyethylene Corporation, trade name: Lexpearl ET6200) was used as a resin constituting the intermediate resin layer, and a low-density polyethylene was used as a resin constituting the base film. Elene (LDPE) resin (trade name: Petrocene 212, manufactured by Tosoh Corporation) was used. By extruding these resins with an extruder, a base film (film 2A) having an intermediate resin layer was produced. The thickness of the LDPE layer was 12.5 μm, and the thickness of EEA was 237.5 μm.

2) Production of film 2B Ethylene-methyl acrylate copolymer (EMA) resin (manufactured by Nippon Polyethylene Corporation, trade name: Lexpearl EB330H) was used as a resin constituting the intermediate resin layer, and low density was used as a resin constituting the base film. Polyethylene (LDPE) resin (trade name: Petrocene 212, manufactured by Tosoh Corporation) was used. By extruding these resins with an extruder, a base film (film 2B) having an intermediate resin layer was produced. The thickness of the LDPE layer was 140.0 μm, and the thickness of EEA was 210.0 μm.

3) Preparation of Film 2C Ethylene-based special copolymer resin (manufactured by Nippon Polyethylene Corporation, trade name: Lexpearl ET720X) is used as the resin constituting the intermediate resin layer, and low-density polyethylene (LDPE) is used as the resin constituting the base film. Resin (Tosoh Corporation, trade name: Petrocene 212) was used. By extruding these resins with an extruder, a base film (film 2C) having an intermediate resin layer was produced. The thickness of the LDPE layer was 50.0 μm, and the thickness of the ethylene-based special copolymer resin layer was 200.0 μm.

4) Preparation of Film 2D A metallocene plastomer resin (manufactured by Nippon Polyethylene Corporation, trade name: Kernel KJ640T) is used as a resin constituting the intermediate resin layer, and a low density polyethylene (LDPE) resin ( Nippon Polyethylene Corporation, trade name: Novatec LL UJ580) was used. By extruding these resins using an extruder, a base film (film 2D) having an intermediate resin layer was produced. The thickness of the LDPE layer is 90 μ. 0 m, and the thickness of the ethylene-based special copolymer resin layer was 210.0 μm.

5) Production of film 2E Ethylene-based special polymer resin (manufactured by Nippon Polyethylene Corporation, trade name: Lexpearl ET220X) is used as the resin constituting the intermediate resin layer, and low-density polyethylene (LDPE) is used as the resin constituting the base film. Resin (Tosoh Corporation, trade name: Petrocene 212) was used. By extruding these resins with an extruder, a base film (film 2E) having an intermediate resin layer was produced. The thickness of the LDPE layer was 150.0 μm, and the thickness of the ethylene-based special copolymer resin layer was 150.0 μm.

6) Production of Film 2F An ethylene-butyl acrylate copolymer resin (manufactured by Arkema, trade name: Lotrile 28BA175) as a resin constituting the intermediate resin layer, and a low-density polyethylene (LDPE) resin as a resin constituting the base film ( Nippon Polyethylene Corporation, trade name: Novatec LL UJ580) was used. By extruding these resins with an extruder, a base film (film 2F) having an intermediate resin layer was produced. The thickness of the LDPE layer was 90.0 μm, and the thickness of the ethylene-butyl acrylate copolymer resin layer was 210.0 μm.

7) Production of film 2G Ethylene-methyl acrylate copolymer resin (manufactured by Nippon Polyethylene Corporation, trade name: EB240H) as a resin constituting the intermediate resin layer, and low-density polyethylene (LDPE) as a resin constituting the base film Resin (Tosoh Corporation, trade name: Petrocene 212) was used. By extruding these resins with an extruder, a base film (film 2G) having an intermediate resin layer was produced. The thickness of the LDPE layer was 90.0 μm, and the thickness of the ethylene-methyl acrylate copolymer resin layer was 210.0 μm.

8) Film formation of film 2H Low density polyethylene (LDPE) resin (manufactured by Tosoh Corporation, trade name: Petrocene 180) as a resin constituting the intermediate resin layer, and low density polyethylene (LDPE) as a resin constituting the base film Resin (Tosoh Corporation, trade name: Petrocene 212) was used. By extruding these resins with an extruder, a base film (film 2H) having an intermediate resin layer was produced. The thickness of the LDPE layer used as the intermediate resin layer was 90.0 μm, and the thickness of the LDPE layer used as the base film was 210.0 μm.

(Example 1)
The pressure-sensitive adhesive composition 1A was applied on a transparent release liner so that the thickness after drying became 30 μm, and dried. The pressure-sensitive adhesive layer on the release liner and the intermediate resin layer of the film 2A were adhered so as to be in contact with each other. Excluding the release liner, a pressure-sensitive adhesive tape for protecting the surface of a semiconductor wafer having the configuration shown in FIG. 1 was obtained.

(Example 2)
In Example 1, in the same manner as in Example 1 except that the pressure-sensitive adhesive composition 1A was changed to the pressure-sensitive adhesive composition 1B and the film 2A was changed to the film 2B, the pressure-sensitive adhesive tape for protecting the surface of the semiconductor wafer shown in FIG. I got

(Example 3)
In Example 1, in the same manner as in Example 1, except that the pressure-sensitive adhesive composition 1A was changed to the pressure-sensitive adhesive composition 1C and the film 2A was changed to the film 2C, the pressure-sensitive adhesive tape for protecting the semiconductor wafer surface shown in FIG. I got

(Example 4)
In Example 1, in the same manner as in Example 1 except that the pressure-sensitive adhesive composition 1A was changed to the pressure-sensitive adhesive composition 1B and the film 2A was changed to the film 2D, the pressure-sensitive adhesive tape for protecting the semiconductor wafer surface shown in FIG. I got

(Comparative Example 1)
A pressure-sensitive adhesive tape for protecting a semiconductor wafer surface was obtained in the same manner as in Example 1, except that the pressure-sensitive adhesive composition 1A was changed to the pressure-sensitive adhesive composition 1C and the film 2A was changed to the film 2E.

(Comparative Example 2)
A pressure-sensitive adhesive tape for protecting a semiconductor wafer surface was obtained in the same manner as in Example 1, except that the pressure-sensitive adhesive composition 1A was changed to the pressure-sensitive adhesive composition 1B and the film 2A was changed to the film 2F.

(Comparative Example 3)
In Example 1, an adhesive tape for protecting the surface of a semiconductor wafer was obtained in the same manner as in Example 1 except that the film 2A was changed to the film 2G.

(Comparative Example 4)
A pressure-sensitive adhesive tape for protecting the surface of a semiconductor wafer was obtained in the same manner as in Example 1, except that the film 2A was changed to the film 2H.

  The following tests were performed on the pressure-sensitive adhesive tapes for protecting the semiconductor wafer surface produced in the above Examples and Comparative Examples, and the performance was evaluated. The evaluation results are shown in Table 1 below. In addition, about the surface protection tape produced in Examples 2-4 and Comparative Examples 1-3, the test was performed similarly to Example 1.

<Test Example 1> Adhesion test (1) Adhesion to bumps having a height of 50 μm On a surface of an 8-inch diameter silicon wafer with bumps (thickness of the silicon wafer itself: 725 μm) having Cu pillar bumps having a height of 50 μm and a bump pitch of 100 μm. Using Nitto Seiki's DR8500III (trade name) under the conditions of a table temperature of 80 ° C., a roller temperature of 60 ° C., a bonding pressure of 0.35 MPa, and a low bonding speed (9 mm / sec), prepared in Example 1 above. The surface protection tape thus obtained was bonded to the wafer. Thus, 25 wafers with a surface protection tape (bump height: 50 μm) were produced. Under these bonding conditions, the intermediate resin layer of the surface protection tape having the intermediate resin layer made of a resin having a melting point of 80 ° C. or lower as a constituent layer melted (the same applies to Test Example 2 below). At that time, the adhesion was visually confirmed, and the presence or absence of air mixing between the surface protection tape and the wafer was examined.
(2) Adhesion to bumps having a height of 200 μm The surface of a silicon wafer with bumps having a diameter of 8 inches and a solder bump having a height of 200 μm and a pitch of 400 μm (thickness 725 μm excluding the bumps) was provided on a surface of Nitto Seiki DR8500III. Using the (trade name), the surface protective tape prepared in Example 1 above was used under the conditions of a table temperature of 80 ° C., a roller temperature of 60 ° C., a bonding pressure of 0.35 MPa, and a low bonding speed (9 mm / sec). Pasted to wafer. Thus, five wafers with a surface protection tape (bump height: 200 μm) were produced. At that time, the adhesion was visually confirmed, and the presence or absence of air mixing between the surface protection tape and the wafer was examined. The evaluation criteria are shown below. A and B pass.

(Evaluation criteria)
A: After bonding, the mixture was allowed to stand still at room temperature (25 ° C.), and no air mixing was observed in any of the wafers with the surface protection tape even after 72 hours.
B: After bonding, the mixture was allowed to stand at room temperature, and no air mixing was observed in any of the wafers with the surface protection tape over 48 hours to 72 hours.
C: After bonding, the mixture was allowed to stand at room temperature, and air was observed on at least one wafer with a surface protection tape within 48 hours after bonding.

<Test Example 2> Grinding test (1) Dust penetration In the same manner as above, a surface protection tape was attached to the wafer, and five wafers with the surface protection tape of Example 1 (bump height: 50 μm) were used. Five wafers with the surface protection tape of Example 1 (bump height: 200 μm) were produced. After bonding the surface protection tape to the wafer for 48 hours, the back surface was ground. A grinder having an in-line mechanism [DFG8760 (trade name) manufactured by Disco Corporation] was used for the back surface grinding. Thereafter, the wafer with the surface protection tape after the grinding was visually checked for the presence or absence of silicon dust between the wafer and the surface protection tape. The back surface of the wafer with the surface protection tape of Example 1 (bump height: 50 μm) was ground until the final ground thickness of the wafer became 50 μm. On the other hand, the wafer with the surface protection tape of Example 1 (bump height: 200 μm) was ground until the final ground thickness of silicon became 200 μm, and evaluated according to the following evaluation criteria.

(Evaluation criteria)
Pass: No dust penetration was observed for both the wafer with the surface protection tape (bump height: 50 μm) and the wafer with the surface protection tape (bump height: 200 μm).
Fail: Dust intrusion was observed in at least one of the wafer with the surface protection tape (bump height: 50 μm) and the wafer with the surface protection tape (bump height: 200 μm).

(2) Transport error The evaluation criteria are as follows. A and B pass.
A: In the grinding test, no transfer error occurred in the grinding device for all wafers.
B: In the grinding test, one transport error occurred in the grinding device.
C: In the grinding test, two or more transport errors occurred in the grinding device.
The “transport error” means that the base film was deformed and vacuum-adsorbed and the wafer with the surface protection tape could not be transported.

(3) Evaluation of Wafer Damage The entire ground wafer with a surface protection tape was visually checked, and the end of the wafer was observed with an optical microscope to check for wafer damage. The evaluation criteria are shown below. "None (A)" is a pass.

(Evaluation criteria)
None (A): No damage was observed visually and under a microscope.
B: Although there was no damage visually, damage was confirmed by a microscope.
C: Damage was visually confirmed.

(4) Warpage evaluation Five wafers with a surface protection tape (bump height: 50 μm) of Example 1 used in the evaluation of dust intrusion were used. (The height from the surface to the lower surface of the highest point of the wafer). The evaluation criteria are shown below. A passes.
(Evaluation criteria)
A: Average warpage height is less than 5 mm B: Average warpage height is 5 mm or more and less than 10 mm C: Average warpage height is 10 mm or more

(5) Evaluation of Peelability The adhesive tape for protecting the surface of each semiconductor wafer produced above was attached at a bonding temperature of 90 ° C. to the surface of an 8-inch diameter semiconductor wafer having a 75 μm height bump (bump pitch 150 μm) on the surface. I combined. Then, using DFG8760 (trade name, manufactured by Disco Co., Ltd.), the back surfaces of the bumped semiconductor wafers bonded with the adhesive tape for protecting the semiconductor wafer surface were ground two by two to a thickness of 200 μm. The semiconductor wafer with the adhesive tape for protecting the semiconductor wafer surface after the grinding is irradiated with ultraviolet rays of 500 mJ / cm ² , and the semiconductor wafer surface is protected using a tensile tester (Twin Column Desktop Model 5567 (trade name)) manufactured by Instron. The adhesive tape was peeled off, and the peeling force when the width at the time of peeling became the maximum (200 mm) was evaluated according to the following criteria. A and B pass.
In Table 1, it is shown as "peelability".

(Evaluation criteria)
A: 20 N / 200 mm or less B: 20 N / 200 mm or less 50 N / 200 mm or less C: 50 N / 200 mm or less

(6) Adhesive residue evaluation Adhesive residue was observed using an optical microscope (Olympus) on five wafers with a surface protective tape (bump height: 50 μm) of Example 1 used in the peelability evaluation. The evaluation criteria are shown below.
(Evaluation criteria)
Pass: No adhesive residue occurred on all wafers with surface protection tape.
Fail: At least one wafer with a surface protection tape has adhesive residue.

<Test Example 3> Heat resistance test The surface protection tape of Example 1 was bonded to a mirror wafer. The bonding conditions are the same as the conditions in Test Example 2 in which the surface protection tape was bonded to the silicon wafer. Then, the tape surface was turned down on a hot plate heated to 90 ° C., and the base film of the surface protection tape was left in contact with the hot plate for 3 minutes. After that, the tape surface was visually observed. Was.
(Evaluation criteria)
Pass: The base film did not melt.
Fail: The base film was melted.

<Measurement of physical properties>
(Melting point, Vicat softening point, MFR)
The melting point and the Vicat softening point of the resin constituting the intermediate resin layer were measured based on JIS K7206. The melt mass flow rate (MFR) of the resin constituting the intermediate resin layer was measured based on JIS K7210. The melting point of the constituent material of the base film was measured based on JIS K 6977-2.
(Adhesive force)
It was measured by the method described above.

<Notes in the table>
The parentheses in the line of the adhesive strength indicate the type of the adhesive composition used for forming the adhesive layer.

As is clear from Table 1, the surface protective tapes of Examples 1 to 4 satisfying the requirements of the present invention were excellent in adhesiveness, and were able to suppress dust intrusion, transport error, and wafer breakage. Furthermore, the surface protection tapes of Examples 1 to 4 were able to suppress warpage in a state of being bonded to the semiconductor wafer surface, and were excellent in peelability, adhesive residue and heat resistance.
In contrast, the surface protection tapes of Comparative Examples 1 to 3 failed at least two evaluation items.

  Although the present invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified, which is contrary to the spirit and scope of the invention as set forth in the appended claims. I believe that it should be interpreted broadly without.

  This application claims the priority based on Japanese Patent Application No. 2017-71346 filed in Japan on March 31, 2017, which is hereby incorporated herein by reference in its entirety. Capture as part of

DESCRIPTION OF SYMBOLS 10 Adhesive tape for semiconductor wafer surface protection 1 Adhesive layer 2 Intermediate resin layer 3 Base film

Claims (9)

An adhesive tape for protecting a semiconductor wafer surface, which is used by heating and bonding at a temperature of 40 ° C. to 90 ° C. on a surface of a semiconductor wafer having an unevenness of 20 μm or more,
The semiconductor wafer surface protection adhesive tape has a base film, an adhesive layer, and an intermediate resin layer between the base film and the adhesive layer,
The thickness of the intermediate resin layer is equal to or greater than the unevenness difference, the melting point or the Vicat softening point of the resin constituting the intermediate resin layer is 40 ° C. to 90 ° C., and the melt mass flow rate of the resin constituting the intermediate resin layer Is 10 g / min to 100 g / min.   The adhesive strength of the pressure-sensitive adhesive layer after irradiating ultraviolet rays to the SUS280 polished surface at 23 ° C. is 0.5 N / 25 mm or more and 5.0 N / 25 mm or less, and the adhesive force to the SUS280 polished surface at 50 ° C. is 0.3 N. The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to claim 1, wherein the pressure-sensitive adhesive tape has a thickness of not less than / 25 mm and not more than 7.0 N / 25 mm.   3. The ratio of the thickness of the base film to the thickness of the intermediate resin layer, wherein the thickness of the base film: the thickness of the intermediate resin layer = 0.5: 9.5 to 7: 3. 4. Adhesive tape for semiconductor wafer surface protection.   The resin constituting the intermediate resin layer is at least one of an ethylene-methyl acrylate copolymer resin, an ethylene-ethyl acrylate copolymer resin, and an ethylene-butyl acrylate copolymer resin. 4. The adhesive tape for protecting a semiconductor wafer surface according to item 1.   The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to any one of claims 1 to 4, wherein a melting point of a constituent material of the base film is 90C to 150C.   The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to claim 1, wherein the thickness of the intermediate resin layer is 100 μm to 400 μm.   The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 5 μm to 40 μm.   The pressure-sensitive adhesive tape for protecting a semiconductor wafer surface according to any one of claims 1 to 7, wherein the thickness of the base film is 25 µm to 100 µm. A semiconductor wafer processing method that includes bonding a semiconductor wafer surface protection adhesive tape to a surface of a semiconductor wafer having an unevenness of 20 μm or more under heating at 40 ° C. to 90 ° C. and grinding the back surface of the semiconductor wafer. So,
The semiconductor wafer surface protection adhesive tape has a base film, an adhesive layer, and an intermediate resin layer between the base film and the adhesive layer,
The thickness of the intermediate resin layer is equal to or greater than the unevenness difference, the melting point or the Vicat softening point of the resin constituting the intermediate resin layer is 40 ° C. to 90 ° C., and the melt mass flow rate of the resin constituting the intermediate resin layer is Is from 10 g / min to 100 g / min.

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