JP7079200B2 - Adhesive tape for protecting the surface of semiconductor wafers and processing methods for semiconductor wafers - Google Patents

Description

The present invention relates to an adhesive tape for protecting the surface of a semiconductor wafer 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, polishing, or the like on 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 a semiconductor chip.

Conventionally, it has been required to increase the thickness of a semiconductor wafer to about 200 to 400 μm by backside grinding or the like. However, with the progress of high-density mounting technology in recent years, it has become necessary to reduce the size of semiconductor chips, and along with this, the thinning of semiconductor wafers is also progressing. Depending on the type of semiconductor chip, it is necessary to make the semiconductor wafer as thin as 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 with a diameter of 5 inches or 6 inches have been the mainstream, but in recent years, processing to convert semiconductor wafers with a diameter of 8 to 12 inches into semiconductor chips has become the mainstream.
The trend of increasing the diameter of semiconductor wafers at the same time as thinning them is particularly remarkable in the field of flash memory in which NAND type and NOR type exist, and in the field of DRAM which is volatile memory. For example, it is not uncommon to grind a semiconductor wafer with a diameter of 12 inches to a thickness of 150 μm or less.

In addition to this, especially in recent years, with the spread of smartphones, the improvement of mobile phone performance, the miniaturization of music players, and the improvement of performance, wafers used for flip chip mounting using semiconductor wafers with electrodes in consideration of impact resistance, etc. There is an increasing demand for thin film. Further, with respect to a semiconductor wafer with bumps, it is becoming necessary to grind the semiconductor wafer portion with a thin film of 100 μm or less. The bumps for flip-chip connection have been densified to improve the transfer speed, and the bump height (protruding height from the semiconductor wafer surface) has become lower, and the distance between the bumps has been increased accordingly. Is getting shorter. In recent years, flip-chip connections have also been implemented in DRAMs, so the thinning of wafers is accelerating.

Flip-chip mounting has attracted attention as a method for mounting semiconductor elements in a minimum area in order to reduce the size and density of electronic devices in recent years. A bump is formed on the electrode of the semiconductor element used for mounting the flip chip, and the bump and the wiring on the circuit board are electrically bonded. As the composition of these bumps, solder and gold are 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, the bumped semiconductor wafer has large irregularities on its surface, so it is difficult to process a thin film. Will get worse. Therefore, the bumped semiconductor wafer is ground using a specially designed surface protective tape (see, for example, Patent Document 1).

However, since these surface protective tapes sufficiently absorb bumps to ensure grindability, it is very difficult to achieve both peelability and peelability. The finished thickness of the chips mounted on the flip chips so far is 200 μm or more, which is a certain thickness, and the rigidity is maintained, so that the chips can be peeled off somehow. However, recently, the finishing thickness of the semiconductor wafer has become even thinner and the bump density has also increased, so that the surface protective tape has caused problems such as not being easily peeled off and residual adhesive. On the contrary, if the peelability is ensured, the adhesion becomes insufficient, causing seapage (for example, infiltration of dust and 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. Wafer level packages do not require stacking of chips, so they are not ground as thin as 50 μm or less like memory semiconductor wafers, but because they have high bumps, they are very fragile even in thick film grinding and have a thickness of 150 μm or less. The problem of semiconductor wafer cracking easily occurs due to the grinding thickness of.

Dedicated surface protection tapes for such semiconductor wafers have been proposed (see Patent Documents 2 to 4). Patent Document 2 describes an adhesive tape for protecting the surface of a semiconductor wafer, which can be firmly adhered to the semiconductor wafer during processing of the semiconductor wafer and can be peeled off without damage or adhesive residue of the semiconductor wafer during peeling. This surface protective tape has a radiation-curable pressure-sensitive adhesive layer on a base film having a layer thickness and a shrinkage value within a specific range. Further, Patent Document 3 is an adhesive tape for surface protection used for backside grinding of a bump wafer having a high bump height. Even if the wafer is ground, the wafer is not damaged or seapage is not generated, and the peeling force is reduced and glue is used. The remaining suppressed adhesive tape for surface protection of semiconductor wafers is disclosed. This surface protective tape has a specific tack force and layer thickness. Further, Patent Document 4 protects the unevenness of the wafer surface and prevents grinding debris and grinding water from entering the wafer surface when grinding the back surface of the wafer to the height difference or less of the unevenness formed on the wafer surface. , And a method for bonding a semiconductor wafer protective pressure-sensitive adhesive sheet, which can prevent the wafer from being damaged after grinding, are disclosed. The surface protective sheet used in this method has an intermediate layer and an adhesive layer in which the loss tangent at 50 ° C to 100 ° C is within a specific range.

Japanese Unexamined Patent Publication No. 2001-203255 Japanese Patent No. 5242830 Japanese Patent No. 5117630 Japanese Unexamined Patent Publication No. 2010-258426

The surface protective tape described in Patent Document 2 can suppress damage and adhesive residue of the semiconductor wafer to a certain extent. Further, the surface protective tape described in Patent Document 3 has good peelability. However, in order to apply a higher bump to a semiconductor wafer having a narrower pitch, the surface protective tape described in Patent Document 2 has room for further improvement in peelability or adhesive residue. Further, the surface protective tape described in Patent Document 3 has room for further improving the adhesiveness, suppressing seapage, and improving the adhesive residue.

Since the surface protective tape used in the method described in Patent Document 4 has extremely good followability, the tape is deformed into an uneven shape when following a bump having a height of 250 μm or more, and is sucked and conveyed. The semiconductor wafer being transported may fall and be damaged in the processing equipment.

In view of the above problems, the present invention can firmly adhere to the semiconductor wafer during processing of the semiconductor wafer, suppress seapage, transfer error in the processing apparatus, and damage to the semiconductor wafer, and can be peeled without adhesive residue during peeling. An object of the present invention is to provide an adhesive tape for protecting the surface of a semiconductor wafer and a method for processing a semiconductor wafer using the adhesive tape.

As a result of diligent studies to solve the above problems, the present inventors have made a resin constituting the intermediate resin layer in the adhesive tape for protecting the surface of a semiconductor wafer having a base film, an intermediate resin layer and an adhesive layer. The melting point or the Vicat softening point and the melt mass flow rate (MFR) are each within a specific range, and the surface protection tape is heat-bonded to the surface of a semiconductor wafer having a specific unevenness difference at a specific temperature to protect the surface. The tape can be firmly adhered to the circuit surface of the semiconductor wafer, and seapage, transfer error in the processing equipment, and damage to the semiconductor wafer can be suppressed during semiconductor wafer processing, and when peeled, it is peeled without adhesive residue. Furthermore, it was found that the warp in the 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 the surface of a semiconductor wafer, which is used by heating and bonding to the surface of a semiconductor wafer having an unevenness difference of 20 μm or more under the conditions of 40 ° C to 90 ° C.
The adhesive tape for protecting the surface of a semiconductor wafer 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 vicut 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 an adhesive tape for protecting the surface of a semiconductor wafer, which is 10 g / 10 min to 100 g / 10 min.
<2>
The adhesive force of the adhesive layer after irradiation with ultraviolet rays on 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 on the SUS280 polished surface at 50 ° C. is 0.3 N. The adhesive tape for protecting the surface of a semiconductor wafer according to <1>, which is 25 mm or more and 7.0 N / 25 mm or less.

<3>
The ratio of the thickness of the base film to the thickness of the intermediate resin layer is <1> or <2>, in which the thickness of the base film: the thickness of the intermediate resin layer = 0.5: 9.5 to 7: 3. Adhesive tape for surface protection of semiconductor wafers described in.
<4>
Any one 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. The adhesive tape for protecting the surface of the semiconductor wafer according to item 1.
<5>
The adhesive tape for protecting the surface of a semiconductor wafer 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 adhesive tape for protecting the surface of a semiconductor wafer 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 the surface of a semiconductor wafer 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 adhesive tape for protecting the surface of a semiconductor wafer according to any one of <1> to <7>, wherein the base film has a thickness of 25 μm to 100 μm.

<9>
A semiconductor wafer processing method that includes grinding the back surface of a semiconductor wafer by heating and adhering an adhesive tape for protecting the surface of the semiconductor wafer to the surface of a semiconductor wafer having an unevenness difference of 20 μm or more under the conditions of 40 ° C to 90 ° C. There,
The adhesive tape for protecting the surface of a semiconductor wafer 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 a method for processing a semiconductor wafer, which is 10 g / 10 min to 100 g / 10 min.

In the description of the present invention, the surface of the semiconductor wafer means a surface having irregularities of the semiconductor wafer, that is, a surface on which an integrated circuit is formed. Further, the surface opposite to this front surface is referred to as a back surface.
In the description of the present invention, the unevenness difference means the distance from the highest portion of the convex portion to the wafer surface or the distance from the deepest portion of the concave portion to the semiconductor wafer surface. For example, when a metal electrode (bump) is formed on a semiconductor wafer, the highest part is the top of the highest bump, and the distance from there to the surface of the semiconductor wafer, that is, the height of the bump is the difference in unevenness. Is. Alternatively, when a scribe line (dicing line) is formed on the semiconductor wafer, the deepest portion 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, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.

The adhesive tape for protecting the surface of a semiconductor wafer of the present invention can reduce the occurrence of sea pages by firmly adhering to the semiconductor wafer during semiconductor wafer processing, and can suppress transfer errors or semiconductor wafer damage in the processing equipment. It can be peeled off, and it is difficult for adhesive residue to occur. Further, the adhesive tape for protecting the surface of the semiconductor wafer of the present invention can suppress warpage in a state of being bonded to the surface of the semiconductor wafer. 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 adhesive tape for protecting the surface of the semiconductor wafer.

It is a schematic schematic sectional view of the adhesive tape for protecting a wafer surface of this invention.

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

[Adhesive tape for protecting the surface of semiconductor wafers]
The adhesive tape for protecting the surface of a semiconductor wafer of the present invention is an adhesive tape for protecting the surface of a semiconductor wafer, which is heat-bonded to the surface of a semiconductor wafer having an unevenness difference of 20 μm or more under the conditions of 40 ° C to 90 ° C. The adhesive tape for protecting the surface of the wafer 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 greater than or equal to the unevenness difference. Further, 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 intermediate resin layer is 10 g / 10 min to 100 g / 10 min.
The pressure-sensitive adhesive layer is not particularly limited, but a radiation-curable pressure-sensitive adhesive layer is preferable. Ionizing radiation] refers to an adhesive layer that cures when irradiated. Ultraviolet rays are preferable as the radiation to be irradiated.

<Base film>
The base film used for the adhesive tape for protecting the surface of the semiconductor wafer of the present invention is not particularly limited. In the adhesive tape for protecting the surface of the semiconductor wafer of 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 preferable. When the melting point of the base film is within the above range, fusion to the bonding roller and the chuck table is prevented in the process of bonding the surface protective tape, and sufficient bonding to a semiconductor wafer having an unevenness of 20 μm or more is sufficient. Can be done. Further, when the dicing die bonding integrated film (DDF) is bonded, the DDF can be bonded by 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 difference of 20 μm or more. Therefore, they are heat-bonded under the condition of 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 composed of an amorphous resin such as styrene, the Vicat softening point is an index because there is no melting point. That is, it is preferable that the Vicat softening point is in the range of the above melting point. If the vicut softening point is too high, fluidity will appear on the back surface of the base material (the surface opposite to the surface in contact with the intermediate resin layer), which may enter the porous portion of the chuck table.

The base film used for the adhesive tape for protecting the surface of the semiconductor wafer of the present invention is preferably made of a resin, and as such a resin, plastic, rubber or the like usually used in the technical field to which the present invention belongs can be used. .. For example, polyolefin resins (eg polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene. -Methyl acrylate copolymer, ethylene-acrylic acid copolymer or a resin composed of a homopolymer or copolymer of a monomer containing an ethylenically unsaturated group such as ionomer), a polyester resin (for example, polyethylene terephthalate or polyethylene na). Phtalate resin), polycarbonate resin, polyurethane resin, engineering plastic (eg polymethylmethacrylate), synthetic rubbers (eg styrene-ethylene-butene or penten copolymers), thermoplastic elastomers (eg polyamide-polypolymer) Copolymer). The base film used for the surface protective tape of the present invention may be a film made of the above-mentioned resin type 1 alone, or a film in which two or more types are combined. Further, the base film used for the surface protective tape of the present invention may be a single layer or a multi-layered film. In the multi-layer base film, it is preferable that the melting point of the material constituting the outermost layer on the opposite side of the intermediate resin layer is in the above range.
In the surface protective 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, more preferably 50 μm or more, in consideration of the balance between the warp straightening force of the semiconductor wafer and the peelability of the surface protective tape, cost and manufacturing aptitude. 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 within the above range, even when the semiconductor wafer is thin-film ground to 50 μm or less, it can be ground while suppressing the transfer error, and the peelability of the surface protective tape can be improved. In addition, "when the semiconductor wafer is thin-film ground to 50 μm or less" means that in the semiconductor wafer having bumps, the back surface is ground until the thickness of the semiconductor wafer itself excluding the bumps is 50 μm or less. Further, in the semiconductor wafer on which the scribe line is formed, it means the distance from the deepest part described above to the back surface.

<Intermediate resin layer>
The adhesive tape for protecting the surface of the semiconductor wafer of the present invention requires an intermediate resin layer. The intermediate resin layer is melted by heat-bonding the surface protective tape to the surface of the semiconductor wafer under a temperature condition of 40 to 90 ° C. The shape of the intermediate resin layer follows. Further, since it is cooled after bonding, the surface protective tape is fixed in a state where the 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 protective tape of the present invention is in the range of 40 ° C. to 90 ° C., more preferably in the range of 60 ° C. to 80 ° C. Since it is necessary to heat and bond the surface protective tape in the range of 40 ° C to 90 ° C to bring the pressure-sensitive adhesive layer into close contact with the surface of the semiconductor wafer, the tensile elastic modulus of the intermediate resin layer needs to change significantly in this temperature range. be. That is, it is a normal temperature when grinding a semiconductor wafer, and if the resin flows at this temperature, the thickness accuracy at the time of grinding is extremely deteriorated, so that it is preferable to have high elasticity. On the other hand, since it is necessary to have low elasticity in order to sufficiently follow the surface of the semiconductor wafer during heat bonding, the intermediate resin layer is required to have contradictory performance. In order to realize this contradictory performance, it is necessary that the melting point or the Vicat softening point, which greatly affects the tensile elastic modulus and the fluidity, is 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 the intermediate resin layer has both a melting point and a Vicat softening point of 40 to 90 ° C.
When the melting point and the bicut softening point of the resin constituting the intermediate resin layer are less than 40 ° C., molding is difficult and the thickness accuracy is deteriorated. That is, the thickness of the intermediate resin layer becomes non-uniform. On the other hand, when the melting point and the bicut softening point of the resin constituting the intermediate resin layer exceed 90 ° C., even if they are heat-bonded under the condition of 40 to 90 ° C., they do not sufficiently follow the shape of the surface of the semiconductor wafer. Dust intrusion 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 a Vicat softening point of 40 to 90 ° C., and has a melt mass flow rate (MFR) of 10 g / 10 min to 100 g / 10 min. be. As described above, the intermediate resin layer having the melting point or the Vicat softening point within the above range is an intermediate resin layer with respect to the shape of the surface of the semiconductor wafer when the surface protective tape is attached to the semiconductor wafer under the condition of 40 to 90 ° C. And the shape of the pressure-sensitive adhesive layer follows. As a result, the pressure-sensitive adhesive layer is sufficiently adhered to the surface of the semiconductor wafer. However, if the melting point or the Vicat softening point of the resin constituting the intermediate resin layer is only within the above range, the surface protective tape itself is deformed into an uneven shape when the unevenness difference of the semiconductor wafer is 250 μm or more, which induces a transfer error. .. By setting the MFR in the range of 10 g / 10 min to 100 g / 10 min, appropriate fluidity is created in the intermediate resin layer during heat bonding, and it is possible to return the deformed surface protective tape to a flat state by following the unevenness. can. This makes it possible to prevent damage due to transfer errors and dropping of the semiconductor wafer. If the melt mass flow rate (MFR) of the intermediate resin layer is less than 10 g / 10 min, the fluidity will be insufficient and the surface protection tape itself will be processed in a deformed state, resulting in transfer errors and damage to the semiconductor wafer. It will occur. On the other hand, if the melt mass flow rate (MFR) of the resin constituting the intermediate resin layer exceeds 100 g / 10 min, it becomes difficult to form a film while maintaining the thickness accuracy (thickness uniformity) of the base material. .. In addition, the thickness accuracy of the semiconductor wafer after grinding also deteriorates. The surface protective tape of the present invention has a melting point or a Vicat softening point of the resin constituting the intermediate resin layer within the above range, and further, the MFR is in the range of 10 g / 10 min to 100 g / 10 min, so that the semiconductor wafer It can also be applied to the processing of semiconductor wafers having an unevenness 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 protective tape of the present invention can be applied is 300 μm or less.
The MFR is measured by the method described in Examples.

Since the intermediate resin layer is not intended to be adhesive, non-adhesive is preferable. Non-adhesive refers to a state in which there is no stickiness at room temperature.
Examples of the resin constituting such a resin layer or resin film include at least one comonomer selected from a radically polymerizable acid comonomer, an acrylic acid ester comonomer, a methacrylic acid ester comonomer, and a carboxylic acid vinyl ester comonomer, and ethylene. A resin made of an ethylene-based copolymer which is a copolymer of the above, a homopolymer of a monomer containing an ethylenically unsaturated group such as ionomer, a resin made of a copolymer, and a resin made of polyethylene (for example, low-density polyethylene). Can be mentioned. In the intermediate resin layer used for the surface protective tape of the present invention, these resins may be used alone or in combination of two or more. Further, the intermediate resin layer may have two or more layers.

Specific examples of the radically 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, and crotonic acid. Examples thereof include unsaturated monocarboxylic acids such as vinylacetic acid and pentenic 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, and butyl acrylate, with methyl acrylate, ethyl acrylate, and butyl acrylate being preferred.

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

Specific examples of the ethylene-based copolymer include, as binary copolymers, for example, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ethylene-maleic anhydride copolymer, and an ethylene-acrylic acid. Examples thereof 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.
Examples of the ternary copolymer include ethylene-acrylic acid-methyl acrylate copolymer, ethylene-acrylic acid-ethyl acrylate copolymer, ethylene-acrylic acid-vinyl acetate copolymer, and 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-acrylic anhydride Examples thereof include ethyl acid copolymer, ethylene-maleic anhydride-methyl methacrylate copolymer, ethylene-maleic anhydride-ethyl methacrylate copolymer, and ethylene-maleic anhydride-vinyl acetate copolymer.
Further, a multidimensional copolymer in which the above comonomer is combined can also be mentioned.
Among the above copolymers, in particular, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-butyl acrylate copolymer. Combined, 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 copolymers, ethylene-ethyl acrylate copolymers and ethylene-butyl acrylate copolymers are preferred.

The proportion of the comonomer in the total mass of ethylene and comomomer used for synthesizing the ethylene-based copolymer is preferably 10% by mass to 50% by mass, more preferably 15% by mass to 40% by mass.
The intermediate resin layer may be a single layer or a plurality of layers as described above. From the viewpoint of manufacturability, the multi-layer is easier to form into a film than the single layer. In the case of a multi-layer, the layer on the base film side is preferably a resin layer or a resin film made of low-density polyethylene or an ethylene-vinyl acetate copolymer, and when the intermediate resin layer of the multi-layer is formed by extrusion. The defect rate can be reduced and the product can be manufactured at low cost. The melting point or Vicat softening point when the intermediate resin layer is a plurality of layers 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 for laminating the resin layer or the resin film is not particularly limited as long as it does not affect the accuracy of the thickness of the resin layer or the resin film and the defects in the resin layer or the resin film. For example, film formation by coextrusion and bonding with an adhesive can be mentioned.

The ratio of the thickness of the base film to the thickness of the intermediate resin layer should be in the range of 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 followability to the surface shape of the semiconductor wafer of the intermediate resin layer. 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 coextrusion or bonding by an adhesive is possible.

The thickness of the intermediate resin layer used for the surface protective tape of the present invention needs to be greater than or equal to the unevenness difference of the semiconductor wafer, but is preferably 100 μm to 400 μm from the viewpoint of manufacturability and thickness accuracy. If it is thinner than the unevenness difference of the semiconductor wafer, the 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 protective tape of the present invention is preferably 10 μm to 30 μm thicker than the unevenness difference of the semiconductor wafer. If the intermediate resin layer is too thick, the thickness accuracy of the semiconductor wafer may deteriorate, and the manufacturing cost also increases. Further, when manufacturing the bump portion of the semiconductor wafer with bumps, an error of about 10 μm occurs, so that if there is a thickness of 10 μm in addition to the average bump height, it is possible to follow with a margin.

<Adhesive layer>
The pressure-sensitive adhesive used for the pressure-sensitive adhesive layer of the surface protective tape of the present invention is not particularly limited, but a radiation-curable pressure-sensitive adhesive is preferable.
The radiation-curable pressure-sensitive adhesive may have the property of being cured by radiation to form a three-dimensional network. A pressure-sensitive adhesive made of a base resin (polymer) having a double bond) and 2) at least two ethylenes in the molecule with respect to a normal rubber-based or (meth) acrylic-based base resin (polymer). It is classified into a pressure-sensitive adhesive containing a low molecular weight compound having a sex unsaturated group (hereinafter referred to as a radiopolymerizable low molecular weight compound) and a photopolymerization initiator.
In the surface protection tape of the present invention, the above 2) is preferable.

1) Adhesive made of a base resin having an ethylenically unsaturated group in the side chain The pressure-sensitive adhesive having an ethylenically unsaturated group in the side chain is preferably a (meth) acrylic pressure-sensitive adhesive, and the base resin is a (meth) acrylic weight. It is more preferable to use a combined or (meth) acrylic polymer as a main component.
Here, "containing a (meth) acrylic polymer as a main component" means that the content of the (meth) acrylic polymer among the polymers or resins constituting the base resin is at least 50% by mass or more. It means that it is preferably 80% by mass or more (100% by mass or less).

The (meth) acrylic polymer has an ethylenically unsaturated group at least in the side chain, so that it can be cured by irradiation. 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 in any way, and for example, a (meth) acrylic polymer having a functional group (α) in the side chain may be used. It has a group having an ethylenically unsaturated group such as a (meth) acrylic loyl group and a (meth) acrylic loyloxy group, and can react with the functional group (α) of the side chain of this (meth) acrylic polymer. Those obtained by reacting with a compound having a functional group (β) are preferable.
The group having an ethylenically unsaturated group may be any group as long as it has a non-aromatic ethylenic double bond, but it may be a (meth) acryloyl group, a (meth) acryloyloxy group, or a (meth) acryloyl. Amino group, allyl group, 1-propenyl group and vinyl group (including styrene or substituted styrene) are preferable, and (meth) acryloyl group and (meth) acryloyloxy group are more preferable.
Examples of the functional group (α) and (β) include a carboxy group, a hydroxyl group, an amino group, a sulfanyl group, a cyclic acid anhydride group, an epoxy group, an isocyanate group (—N = C = O) and the like.

Here, when one of the functional group (α) and the functional group (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 used. Examples include an epoxy group and an isocyanate group. When one functional group is a cyclic acid anhydride group, the other functional group may be a carboxy group, a hydroxyl group, an amino group or 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 (particularly, a functional group in the alcohol portion). Those having α)] can be obtained by using the monomer component.
The (meth) acrylic polymer having a functional group (α) in the side chain is preferably a copolymer, and this copolymer component is a (meth) acrylic acid alkyl ester, particularly a functional group (in particular, the alcohol portion). A (meth) acrylic acid alkyl ester in which α) or a group having an ethylenically unsaturated group is not substituted is preferable.

Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, and hexyl (meth). ) 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 alone or in combination of two or more, and the alcohol portion having 5 or less carbon atoms and 6 to 12 carbon atoms may be used in combination. preferable.

Since the glass transition point (Tg) becomes lower as the monomer having a larger carbon number 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 weight compound having a carbon-carbon double bond such as vinyl acetate, styrene, and acrylonitrile for the purpose of improving compatibility and various performances. In this case, these monomer components are also preferable. The content of the above 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, carcinous acid, itaconic acid, fumaric acid, phthalic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, and glycol. Monoacrylates, glycol monomethacrylates, N-methylolacrylamides, N-methylolmethacrylicamides, allyl alcohols, N-alkylaminoethylacrylates, N-alkylaminoethylmethacrylates, acrylamides, methacrylates, maleic anhydride, Urethane of some of the isocyanate groups of itaconic anhydride, fumaric anhydride, phthalic anhydride, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and polyisocyanate compound with a hydroxyl group or a monomer having a carboxy group and an ethylenically unsaturated group. And so on.

Among these, acrylic acid, methacrylic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, glycidyl acrylates and glycidyl methacrylates are preferable, and acrylic acid, methacrylic acid, 2-hydroxyalkyl acrylates and 2-hydroxyalkyl methacrylates are preferable. Classes are more preferable, and methacrylic acid, 2-hydroxyalkyl acrylates, and 2-hydroxyalkyl methacrylates are even 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, and for example, a (meth) acrylic acid having an isocyanate (-N = C = O) group in the alcohol portion. Examples thereof include ester, and among them, (meth) acrylic acid alkyl ester substituted with an isocyanate (-N = C = O) group is preferable. Examples of such a monomer include 2-isocyanatoethyl methacrylate and 2-isocyanatoethyl acrylate.
Moreover, the preferable compound when the functional group (β) is other than the isocyanate group includes the compound exemplified by the (meth) acrylic monomer having a functional group (α).

The compound having an ethylenically unsaturated group and a functional group (β) is a functional group (α) on the side chain of the polymer in addition to the (meth) acrylic polymer having a functional group (α) on the side chain, preferably. By reacting with the 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, a ketone-based, ester-based, alcohol-based, or aromatic-based solvent can be used as the organic solvent when the reaction is carried out by solution polymerization. Among them, toluene and Generally, it is a good solvent for (meth) acrylic polymers such as ethyl acetate, isopropyl alcohol, benzenemethyl cellosolve, ethyl cellosolve, acetone and methyl ethyl ketone, and a solvent having a boiling point of 60 to 120 ° C. is preferable. As the polymerization initiator, radical generators such as azobis-based agents such as α, α'-azobisisobutyronitrile and organic peroxide-based agents 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. Further, regarding the adjustment of the molecular weight, it is preferable to use a solvent such as mercaptan or carbon tetrachloride. Note that this reaction is not limited to solution polymerization, and other methods such as bulk polymerization and suspension polymerization may be used.

The mass 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 mass average molecular weight is too large, the pressure-sensitive adhesive after irradiation is not flexible and becomes brittle when irradiated, so that adhesive residue is generated on the surface of the semiconductor chip during peeling. If the mass average molecular weight is too small, the cohesive force before irradiation is small and the adhesive force is weak, so that the semiconductor chip cannot be sufficiently held during dicing, and chip skipping may occur. In addition, curing is insufficient even after irradiation, and adhesive residue is generated on the surface of the semiconductor chip during peeling. In order to prevent these as much as possible, it is preferable that the mass average molecular weight is 200,000 or more.
In the description of the present invention, the mass average molecular weight is the 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 −70 to −10 ° C., more preferably −50 to −10 ° C. If the glass transition point is too low, the fluidity of the adhesive will be high and it will cause adhesive residue. It causes penetration into the wafer surface.

The acid value of the base resin having an ethylenically unsaturated group in the side chain [the number of mg 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 to 20 are more preferable.
The hydroxyl value of the base resin having an ethylenically unsaturated group in the side chain [the number of 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 when the adhesive tape for protecting the surface of the semiconductor wafer is peeled off is further excellent.

The acid value and hydroxyl value are prepared for the (meth) acrylic polymer having a functional group (α) in the side chain and the (meth) acrylic polymer having an ethylenically unsaturated group. At the stage of reacting the functional group (α) of the side chain with the compound having a functional group (β) capable of reacting, the desired product 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, a photopolymerization initiator such as isopropylbenzoin ether, isobutylbenzoin ether, benzophenone, phenyldimethoxyacetylbenzene, Michler's ketone, etc. Chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, benzyldimethylketal, α-hydroxycyclohexylphenylketone, 2-hydroxymethylphenylpropane and the like can be used.
The blending amount of these photopolymerization initiators is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the base resin. If the blending amount is too small, the reaction will be insufficient, and if the blending amount is too large, the amount of small molecule components will increase, which will affect the pollutability.

The pressure-sensitive adhesive made of a base resin having an ethylenically unsaturated group in the side chain preferably contains a cross-linking agent.
Any such cross-linking agent may be used, but a cross-linking agent selected from the group of polyisocyanates, melamine / formaldehyde resins and epoxy resins is preferable.
Among these, polyisocyanates are preferable in the surface protective tape of the present invention.

The polyisocyanates are not particularly limited, and are, for example, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-[2,2-bis (4). -Phenoxyphenyl) propane] Aromatic isocyanates such as diisocyanates, hexamethylene diisocyanates, 2,2,4-trimethyl-hexamethylene diisocyanates, isophorone diisocyanates, 4,4'-dicyclohexylmethane diisocyanates, 2,4'-dicyclohexylmethane diisocyanates , Lysine diisocyanate, lysine triisocyanate and the like. Specifically, Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name) and the like can be used.

As the melamine / formaldehyde resin, specifically, Nicarac MX-45 (manufactured by Sanwa Chemical Co., Ltd., trade name), Melan (manufactured by Hitachi Kasei Kogyo Co., Ltd., trade name) and the like can be used.

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

The blending amount of the cross-linking agent is preferably 0.1 to 10 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the base resin.
After the pressure-sensitive adhesive is applied, the cross-linking agent allows the base resin to form a cross-linked structure, and the cohesive force of the pressure-sensitive adhesive can be improved.

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

2) Adhesive containing a 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 an ordinary chlorinated polypropylene resin or acrylic used for the pressure-sensitive adhesive. Resin [(meth) acrylic resin], polyester resin, polyurethane resin, epoxy resin and the like can be used.

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

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 1,100 to 20,000, further preferably 1,300 to 20,000, and particularly preferably 1,500 to 10,000.

The radiopolymerizable low molecular weight compound has at least two ethylenically unsaturated groups (radiopolymerizable carbon-carbon double bonds) in the molecule, which can be three-dimensionally networked by irradiation, and is 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 above oligomer is a radiation-polymerizable low molecular weight compound having an ethylenically unsaturated group.

Specific examples of the radiopolymerizable low molecular weight compound include trimethylolpropanetri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol monohydroxypenta (meth) acrylate. Dipentaerythritol hexa (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, oligoester (meth) acrylate, etc. A (meth) acrylate compound can be applied.

Further, in addition to the (meth) acrylate-based compound as described above, a urethane (meth) acrylate-based oligomer can also be used as the radiation-polymerizable low molecular weight compound. Urethane (meth) acrylate-based oligomers include polyol compounds such as polyester type or polyether type and polyvalent isocyanate compounds (for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3). -A (meth) acrylate having a hydroxy group (for example,) is added to a terminal isocyanate urethane prepolymer obtained by reacting with xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4-diisocyanate, etc.). , 2-Hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, etc.).
The radiation-polymerizable low molecular weight compound may be used alone or in combination of two or more.

The radiation-curable pressure-sensitive adhesive may contain a photopolymerization initiator, if necessary. The photopolymerization initiator is not particularly limited as long as it reacts with radiation transmitted through the substrate, and ordinary ones can be used. For example, benzophenones such as benzophenone, 4,4'-dimethylaminobenzophenone, 4,4'-diethylaminobenzophenone, 4,4'-dichlorobenzophenone, acetophenone, diethoxyacetophenone, acetophenone such as phenyldimethoxyacetylbenzene, 2- Anthraquinones such as ethyl anthraquinone and t-butyl anthraquinone, 2-chlorothioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzyl, 2,4,5-triary-luimidazole dimer (lofin dimer), aclysine compound , Acylphosphinoxides, etc., which can be used alone or in combination of two or more.

The amount of the photopolymerization initiator added is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 7.5 parts by mass, still more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the base resin. .. If the amount of the photopolymerization initiator added is too large, radiation curing will occur at multiple points and rapidly, resulting in a large radiation curing shrinkage. 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 cross-linking agent.
Examples of the curing agent or cross-linking agent include a polyvalent isocyanate compound, a polyvalent epoxy compound, a polyvalent aziridine compound, and a chelate compound.

The polyvalent isocyanate compound is not particularly limited, and is, for example, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-[2,2-bis (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 Examples thereof include diisocyanate, lysine diisocyanate, and lysine triisocyanate. Specifically, Coronate L [manufactured by Nippon Polyurethane Industry Co., Ltd., trade name] and the like can be used.

Examples of the polyvalent epoxy compound include epoxy resins, and examples thereof include ethylene glycol diglycidyl ether, terephthalic acid diglycidyl ester acrylate, and anilines in which N atoms are substituted with two glycidyl groups. Further, the above-mentioned TETRAD-X can also be used.
Examples of anilines include N, N'-tetraglycidyl-m-phenylenediamine.

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

The blending amount of the curing agent or the cross-linking agent is preferably 0.1 to 10 parts by mass, more preferably 0.1 to 5.0 parts by mass, and 0.5 to 4.0 parts by mass with respect to 100 parts by mass of the base resin. Is even more preferable.

(Thickness of adhesive layer)
The thickness of the pressure-sensitive adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 20 μm or more from the viewpoint of manufacturability. 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 plurality of layers, and in that case, at least the pressure-sensitive adhesive of the outermost layer in contact with the surface of the semiconductor wafer is preferably a radiation-curable pressure-sensitive adhesive.

(Characteristics of adhesive layer or adhesive)
[Contents of ethylenically unsaturated groups in the radiation-curable pressure-sensitive adhesive layer]
In the surface protective tape of the present invention, the content of ethylenically unsaturated groups (radiopolymerizable carbon-carbon double bonds) contained in the radiation-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is 0.2 to 2.0 mmol /. g is preferable.
The content of the ethylenically unsaturated group contained in the radiation-curable pressure-sensitive adhesive is the sum of all the ethylenically unsaturated groups contained in the compound having the 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 the 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 0.2 to 1.8 mmol / g, more preferably 0.2 to 1.5 mmol / g, and 0.5 to 1.5 mmol / g. g is more preferable.
When the pressure-sensitive adhesive layer is a multi-layer, the content of ethylenically unsaturated groups contained in the radiation-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is within the above range when all the pressure-sensitive adhesive layers are regarded as one layer. It is preferable that the above range is satisfied, and it is more preferable that each layer satisfies the above range.

The content of ethylenically unsaturated groups contained in the radiation-curable pressure-sensitive adhesive depends on the number of ethylenically unsaturated groups contained in the above-mentioned compound having a 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 ethylenically unsaturated groups contained in these compounds. Further, the iodine value of the radiation-curable pressure-sensitive adhesive [the number of g of iodine (I ₂ ) added to a total of 100 g of the base resin and the radiation-polymerizable low molecular weight compound] was obtained, and the molecular weight of I ₂ was 253.8. , This value can be obtained by converting the unit to mmol / g.

[Adhesive strength to SUS plate after UV curing]
The adhesive strength of the pressure-sensitive adhesive layer of the surface protective tape of the present invention after irradiation with ultraviolet rays 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 5.0 N / 25 mm or less, more preferably 3.0 N / 25 mm or less, still more preferably 1.5 N / 25 mm or less. The 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 7.0 N / 25 mm or less, more preferably 4.0 N / 25 mm or less, and even more preferably 2.5 N / 25 mm or less. This adhesive strength is a characteristic of the surface protective tape itself.
The term "after irradiation with ultraviolet rays" means after the entire pressure-sensitive adhesive layer is irradiated and cured so that the cumulative irradiation amount of ultraviolet rays is 500 mJ / cm ² .

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 protective tape before irradiation. The test piece is finished with No. 280 water-resistant abrasive paper specified in JIS R 6253, and a 2 kg rubber roller is crimped on a SUS steel plate having a thickness of 1.5 mm to 2.0 mm specified in JIS G 4305 over three reciprocations. After leaving it at room temperature (25 ° C.) for 1 hour, the pressure-sensitive adhesive layer is cured by irradiating it with ultraviolet rays having a cumulative irradiation amount of 500 mJ / cm ² . After the pressure-sensitive adhesive layer is cured, the average value of the pressure-sensitive adhesive strength at three points is obtained using a tensile tester conforming to JIS B 7721 whose measured value is in the range of 15 to 85% of its capacity. The adhesive strength is measured at a tensile speed of 50 mm / min at room temperature and humidity of 50% by a 90 ° peeling method. In this test, before crimping the test piece to the SUS steel sheet, the SUS steel sheet 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 manufactured by Instron: Twin Column Desktop Model 5567 (trade name) can be used.

The adhesive strength of the SUS polished surface after UV curing is preferably adjusted by appropriately adjusting the type and amount of the compound used for the pressure-sensitive adhesive, the type and amount of additives such as a cross-linking agent, the thickness of the pressure-sensitive adhesive layer, and the like. Can be in the range.
If the adhesive force to the SUS polished surface is made too small, the curing shrinkage due to the cross-linking reaction becomes large, so that the peeling force from an adherend having a large surface unevenness such as a bump wafer becomes large. If the apparent adhesive force to the SUS polished surface is too large, radiation curing will be insufficient, resulting in poor peeling and adhesive residue.

<Peeling liner>
The adhesive tape for protecting the surface of the semiconductor wafer may have a release liner on the adhesive layer. As the release liner, a polyethylene terephthalate film or the like that has been subjected to a silicone mold release treatment is used. Further, if necessary, a polypropylene film or the like that is not subjected to a silicone mold release treatment is also used.

<< Semiconductor wafer processing method >>
The method for processing a semiconductor wafer of the present invention is a method for processing a semiconductor wafer using the adhesive tape for protecting the surface of the semiconductor wafer of the present invention.
The adhesive tape for protecting the surface of a semiconductor wafer of the present invention may be used in any process of processing 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 mentioned.

The adhesive tape for protecting the surface of a semiconductor wafer of the present invention is used by being bonded to the surface of a semiconductor wafer having an unevenness difference of 20 μm or more.
It is more preferable to apply it to a semiconductor wafer having a difference in unevenness [the height of the bump (electrode) and the depth of the scribe line] of 20 to 400 μm, and even more preferably to apply it to a semiconductor wafer having a thickness 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 the pitch is 0.5 to 3 times or less, preferably 1 to 2 times or less the height of the bumps (the height of the bumps). It can be applied to the one (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 semiconductor wafers in which bumps are uniformly arranged on the entire surface.

The thickness of the semiconductor wafer is preferably 20 to 500 μm, more preferably 50 to 200 μm, still more preferably 80 to 200 μm, in terms of the thickness of the semiconductor wafer grounded on the back surface by a processing method using an adhesive tape for protecting the surface of the semiconductor wafer.
By using the adhesive tape for protecting the surface of the semiconductor wafer of the present invention, a thin film semiconductor wafer can be obtained with a high yield. This method for processing a semiconductor wafer is suitable as a method for manufacturing a semiconductor wafer with electrodes which is thin-film ground to a size of 50 μm or less.

The method for processing a semiconductor wafer of the present invention is a step of attaching the semiconductor wafer surface protection adhesive tape of the present invention to the semiconductor wafer surface and then irradiating with radiation, particularly ultraviolet rays, to peel off the semiconductor wafer surface protection adhesive tape. It is preferable to include.

Specifically, first, the adhesive tape for protecting the surface of the semiconductor wafer of the present invention is attached to the circuit pattern surface (surface) of the semiconductor wafer so that the adhesive layer serves as the bonding surface. Next, the surface side of the semiconductor wafer without the circuit pattern is ground until the thickness of the semiconductor wafer becomes a predetermined thickness, for example, 10 to 200 μm. After that, the semiconductor wafer surface protection adhesive tape is placed on the heating adsorption table with the bonded surface facing down, and in that state, a dicing die bonding film is placed on the ground side of the semiconductor wafer without a circuit pattern. You may stick them together.
A dicing step is performed, and then a heat seal type (heat fusion type) or adhesive type release tape is adhered to the back surface of the base film of the adhesive tape for protecting the surface of the semiconductor wafer, and the adhesive for protecting the surface of the semiconductor wafer is adhered from the semiconductor wafer. Peel off the tape.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

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

1) Preparation of Adhesive Composition 1A A copolymer having a mass 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. With respect to 100 parts by mass of this copolymer, 100 parts by mass of a urethane acrylate oligomer having a mass average molecular weight of 3,000 and having a hydroxy group as a functional group (β) and coronate L of polyisocyanate [trade name, Japan]. Polyurethane Industry Co., Ltd.] 5.0 parts by mass and SPEEDCURE BKL [trade name, manufactured by DKSH Japan Co., Ltd.] 5.0 parts by mass as a photopolymerization initiator were added and mixed to obtain a pressure-sensitive adhesive composition 1A.

2) Preparation of 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 to obtain a meta having a mass average molecular weight of 1 million. An acrylic polymer was obtained. 2.0 parts by mass of an epoxy-based curing agent was mixed with 100 parts by mass of this methacrylic polymer to obtain a pressure-sensitive adhesive composition B.

3) Preparation of Adhesive 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. With respect to 100 parts by mass of this copolymer, 100 parts by mass of a urethane acrylate oligomer having a acrylate trifunctionality 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 coronate L of polyisocyanate. , 0.5 part by mass of TETRAD-X [manufactured by Mitsubishi Gas Chemicals Co., Ltd.] of epoxy resin 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.

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

1) Preparation of film 2A A resin constituting a base film using an ethylene- ethyl acrylate copolymer (EEA) resin (manufactured by Nippon Polyethylene Co., Ltd., trade name: Lexpearl EEA A 6200) as a resin constituting the intermediate resin layer. A low-density polyethylene (LDPE) resin (manufactured by Toso Co., Ltd., trade name: Petrosen 212) was used as the resin. 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 the EEA was 237.5 μm.

2) Preparation of film 2B Ethethylene-methyl acrylate copolymer (EMA) resin (manufactured by Nippon Polyethylene, trade name: Lexpearl EB330H) is used as the resin constituting the intermediate resin layer, and the resin having a low density is used as the resin constituting the base film. Polyethylene (LDPE) resin (manufactured by Toso Co., Ltd., trade name: Petrosen 212) 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 the EEA was 210.0 μm.

3) Preparation of film 2C An ethylene-based special copolymer resin (manufactured by Nippon Polyethylene, 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. A resin (manufactured by Toso Co., Ltd., trade name: Petrosen 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 Metallocene plastomer resin (manufactured by Nippon Polyethylene Co., Ltd., trade name: Kernel KJ640T) is used as the resin constituting the intermediate resin layer, and low-density polyethylene (LDPE) resin (LDPE) resin is used as the resin constituting the base film. A product name: Novatec LL UJ580) manufactured by Nippon Polyethylene Co., Ltd. was used. By extruding these resins with an extruder, a base film (film 2D) having an intermediate resin layer was produced. The thickness of the LDPE layer is 90 μ. At 0 m, the thickness of the ethylene-based special copolymer resin layer was 210.0 μm.

5) Preparation of film 2E An ethylene-based special polymer resin (manufactured by Nippon Polyethylene, 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. A resin (manufactured by Toso Co., Ltd., trade name: Petrosen 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) Preparation of film 2F Ethylene-butyl acrylate copolymer resin (manufactured by Alchema, trade name: Rotril 28BA175) as the resin constituting the intermediate resin layer, and low-density polyethylene (LDPE) resin (LDPE) resin as the resin constituting the base film. A product name: Novatec LL UJ580) manufactured by Nippon Polyethylene Co., Ltd. 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) Film formation of film 2G Ethethylene-methyl acrylate copolymer resin (manufactured by Nippon Polyethylene, trade name: EB240H) as the resin constituting the intermediate resin layer, and low-density polyethylene (LDPE) as the resin constituting the base film. A resin (manufactured by Toso Co., Ltd., trade name: Petrosen 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 Toso Co., Ltd., trade name: Petrosen 180) as the resin constituting the intermediate resin layer, and low-density polyethylene (LDPE) as the resin constituting the base film. A resin (manufactured by Toso Co., Ltd., trade name: Petrosen 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 onto a transparent release liner and dried so that the thickness after drying was 30 μm. The pressure-sensitive adhesive layer on the release liner and the intermediate resin layer of the film 2A were bonded to each other so as to be in contact with each other, and the release liner was removed to obtain an adhesive tape for protecting the surface of the semiconductor wafer having the configuration shown in FIG.

( Reference example 2)
In the first embodiment, the adhesive tape for protecting the surface of the semiconductor wafer having the configuration shown in FIG. 1 is the same as that of the first embodiment except that the pressure-sensitive adhesive composition 1A is changed to the pressure-sensitive adhesive composition 1B and the film 2A is changed to the film 2B. Got

( Reference example 3)
In the first embodiment, the adhesive tape for protecting the surface of the semiconductor wafer having the configuration shown in FIG. 1 is the same as that of the first embodiment except that the pressure-sensitive adhesive composition 1A is changed to the pressure-sensitive adhesive composition 1C and the film 2A is changed to the film 2C. Got

(Example 4)
In the first embodiment, the adhesive tape for protecting the surface of the semiconductor wafer having the configuration shown in FIG. 1 is the same as that of the first embodiment except that the pressure-sensitive adhesive composition 1A is changed to the pressure-sensitive adhesive composition 1B and the film 2A is changed to the film 2D. Got

(Comparative 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 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)
An adhesive tape for protecting the surface of a semiconductor wafer 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)
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 in Example 1.

(Comparative Example 4)
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 2H in Example 1.

The following tests were performed on the adhesive tapes for protecting the surface of the semiconductor wafer produced in the above Examples , Reference Examples and Comparative Examples, and their performances were evaluated. The evaluation results are shown in Table 1 below. The surface protective tapes produced in Reference Examples 2 and 3, Example 4 and Comparative Examples 1 to 3 were also tested in the same manner as in Example 1.

<Test Example 1> Adhesion test (1) Adhesion to a bump with a height of 50 μm On the surface of a silicon wafer with a bump (thickness 725 μm of the silicon wafer itself) having a Cu pillar bump with a height of 50 μm and a bump pitch of 100 μm and having a diameter of 8 inches. Made in Example 1 above using DR8500III (trade name) manufactured by Nitto Seiki Co., Ltd. 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 bonding speed of low speed (9 mm / sec). The surface protection tape was attached to the wafer. In this way, 25 wafers with surface protective tape (bump height: 50 μm) were produced. Under these bonding conditions, the intermediate resin layer of the surface protective tape having an intermediate resin layer made of a resin having a melting point of 80 ° C. or lower as a constituent layer was melted (the same was true for Test Example 2 below). The adhesion at that time was visually confirmed, and the presence or absence of air contamination between the surface protective tape and the wafer was examined.
(2) Adhesion to bumps with a height of 200 μm DR8500III manufactured by Nitto Seiki Co., Ltd. on the surface of an 8-inch diameter bumped silicon wafer (thickness 725 μm excluding bumps) having solder bumps with a height of 200 μm and a bump pitch of 400 μm. Using (trade name), the surface protective tape produced 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 bonding speed of low speed (9 mm / sec). It was bonded to the wafer. In this way, five wafers with surface protective tape (bump height: 200 μm) were produced. The adhesion at that time was visually confirmed, and the presence or absence of air contamination between the surface protective tape and the wafer was examined. The evaluation criteria are shown below. A and B pass.

(Evaluation criteria)
A: After bonding, the wafer was allowed to stand at room temperature (25 ° C.), and even after 72 hours, no air contamination was observed in all the wafers with surface protective tape.
B: After bonding, the wafer was allowed to stand at room temperature, and no air contamination was observed in all the wafers with surface protective tape within more than 48 hours and within 72 hours.
C: After bonding, the mixture was allowed to stand at room temperature, and air was observed on at least one wafer with surface protective tape within 48 hours after bonding.

<Test Example 2> Grinding test (1) Dust intrusion In the same manner as above, the surface protection tape was attached to the wafer, and the wafer was carried out with 5 wafers with surface protection tape (bump height: 50 μm) of Example 1. Five wafers with surface protection tape (bump height: 200 μm) of Example 1 were produced. After the surface protective tape was attached to the wafer and allowed to stand for 48 hours, the back surface was ground. For this back surface grinding, a grinder having an in-line mechanism [DFG8760 (trade name) manufactured by Disco Corporation] was used. Then, with respect to the wafer with the surface protection tape after grinding, the presence or absence of silicon dust intrusion between the wafer and the surface protection tape was visually confirmed. For the wafer with surface protection tape (bump height: 50 μm) of Example 1, backside grinding was performed until the final grinding thickness of the wafer reached 50 μm. On the other hand, the wafer with the surface protective tape (bump height: 200 μm) of Example 1 was subjected to backside grinding until the final grinding thickness of silicon reached 200 μm, and evaluated according to the following evaluation criteria.

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

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

(3) Evaluation of Wafer Damage The entire ground wafer with surface protective tape was visually confirmed, and the edge 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): There was no damage by visual inspection and microscopic observation.
B: There was no visual damage, but damage was confirmed by a microscope.
C: Damage was visually confirmed.

(4) Warpage evaluation For the five wafers with surface protection tape (bump height: 50 μm) of Example 1 used in the evaluation of dust intrusion, the warp height (wafer with surface protection tape is placed on a flat plate and the flat plate is placed. The height from the surface to the bottom surface of the highest point of the warped wafer) was measured. The evaluation criteria are shown below. A is a pass.
(Evaluation criteria)
A: The average value of the warp height is less than 5 mm B: The average value of the warp height is 5 mm or more and less than 10 mm C: The average value of the warp height is 10 mm or more

(5) Detachability evaluation Adhesive tape for protecting the surface of each semiconductor wafer manufactured above is attached to the surface of an 8-inch diameter semiconductor wafer having bumps (bump pitch 150 μm) with a height of 75 μm at a bonding temperature of 90 ° C. It fits. Then, using DFG8760 (trade name) manufactured by DISCO Co., Ltd., the back surfaces of the bumped semiconductor wafers bonded with the above-mentioned adhesive tape for protecting the surface of the semiconductor wafer were ground two by two to a thickness of 200 μm. The semiconductor wafer with adhesive tape for protecting the surface of the semiconductor wafer after grinding is irradiated with ultraviolet rays of 500 mJ / cm ² , and the surface of the semiconductor wafer is protected using a tensile tester manufactured by Instron (twin column desktop model 5567 (trade name)). 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 "peeling property".

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

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

<Test Example 3> Heat resistance test The surface protective tape of Example 1 was attached to the mirror wafer. The bonding conditions are the same as the conditions for bonding the surface protective tape to the silicon wafer in Test Example 2. Then, the tape surface was turned downward on the hot plate heated to 90 ° C., the base film of the surface protective tape was in contact with the hot plate, and the mixture was allowed to stand for 3 minutes, and then the tape surface was visually observed. rice field.
(Evaluation criteria)
Pass: The base film did not melt.
Fail: The base film has 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 K 7206. The melt mass flow rate (MFR) of the resin constituting the intermediate resin layer was measured based on JIS K 7210. 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.

<Note to the table>
The brackets in the adhesive strength line indicate the type of adhesive composition used to form the adhesive layer.

As is clear from Table 1 , the surface protective tapes of Examples 1, Reference Examples 2, 3 and 4 have excellent adhesion and can suppress dust intrusion, transfer error, and wafer breakage. Further, the surface protective tapes of Examples 1, Reference Examples 2, 3 and 4 can suppress warpage in a state of being bonded to the surface of the semiconductor wafer, and are excellent in peelability, adhesive residue and heat resistance.
On the other hand, the surface protective tapes of Comparative Examples 1 to 3 failed at least two evaluation items.

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

The present application claims priority based on Japanese Patent Application No. 2017-71346 filed in Japan on March 31, 2017, both of which are described herein with reference to this. Incorporate as part of.

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

Claims (8)

An adhesive tape for protecting the surface of a semiconductor wafer, which is used by heating and bonding to the surface of a semiconductor wafer having an unevenness difference of 20 μm or more under the conditions of 40 ° C to 90 ° C.
The adhesive tape for protecting the surface of a semiconductor wafer 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 resin constituting the intermediate resin layer is a metallocene plastomer resin, and the melting point or the Vicat softening point of the resin constituting the intermediate resin layer is 40 ° C. to 90 ° C. An adhesive tape for protecting the surface of a semiconductor wafer, which is at ° C. and has a melt mass flow rate of 10 g / 10 min to 100 g / 10 min of the resin constituting the intermediate resin layer. The adhesive force of the adhesive layer after irradiation with ultraviolet rays on 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 on the SUS280 polished surface at 50 ° C. is 0.3 N. The adhesive tape for protecting the surface of a semiconductor wafer according to claim 1 , which is 25 mm or more and 7.0 N / 25 mm or less. The first or second aspect of the present invention, wherein the ratio of the thickness of the base film to the thickness of the intermediate resin layer is the thickness of the base film: the thickness of the intermediate resin layer = 0.5: 9.5 to 7: 3. Adhesive tape for surface protection of semiconductor wafers. The adhesive tape for protecting the surface of a semiconductor wafer according to any one of claims 1 to 3 , wherein the constituent material of the base film has a melting point of 90 ° C to 150 ° C. The adhesive tape for protecting the surface of a semiconductor wafer according to any one of claims 1 to 4 , wherein the thickness of the intermediate resin layer is 100 μm to 400 μm. The pressure-sensitive adhesive tape for protecting the surface of a semiconductor wafer according to any one of claims 1 to 5 , wherein the pressure-sensitive adhesive layer has a thickness of 5 μm to 40 μm. The adhesive tape for protecting the surface of a semiconductor wafer according to any one of claims 1 to 6 , wherein the base film has a thickness of 25 μm to 100 μm. A semiconductor wafer processing method that includes grinding the back surface of a semiconductor wafer by heating and adhering an adhesive tape for protecting the surface of the semiconductor wafer to the surface of a semiconductor wafer having an unevenness difference of 20 μm or more under the conditions of 40 ° C to 90 ° C. There,
The adhesive tape for protecting the surface of a semiconductor wafer 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 resin constituting the intermediate resin layer is a metallocene plastomer resin, and the melting point or the Vicat softening point of the resin constituting the intermediate resin layer is 40 ° C. to 90 ° C. A method for processing a semiconductor wafer, wherein the temperature is 1 ° C. and the melt mass flow rate of the resin constituting the intermediate resin layer is 10 g / 10 min to 100 g / 10 min.

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