JP2003301151A - Double-coated pressure-sensitive adhesive sheet and its use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-coated pressure-sensitive adhesive sheet for accurately and efficiently processing a workpiece, especially a double-coated pressure-sensitive adhesive sheet which is suitable for a process wherein IC chips with a high thickness accuracy can be subjected to backside grinding and dicing in a high yield in the same state by decreasing the warp in grinding a very thin or large-diameter silicon wafer and decreasing the breakage during transportation; and a method for producing a highly reliable semiconductor using the double-coated pressure-sensitive adhesive sheet. <P>SOLUTION: The double-coated pressure-sensitive adhesive sheet comprises a shrinkable substrate, an energy ray-curable pressure-sensitive adhesive layer formed on one side of the substrate, and a pressure-sensitive adhesive layer having an elastic modulus at 120°C of 5×10<SP>5</SP>Pa or lower and formed on the other side of the substrate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided pressure-sensitive adhesive sheet, and more particularly to a double-sided pressure-sensitive adhesive sheet used for temporarily holding a fragile work piece on a hard plate and processing or protecting it.

[0002]

2. Description of the Related Art In recent years, with the spread of IC cards, further thinning is demanded. Therefore, in the past, the thickness was 35
A semiconductor chip with a thickness of 50 μm
It is necessary to reduce the thickness to μm or less.
It has been conventionally practiced to grind the back surface of a wafer after forming a circuit pattern. At this time, an adhesive sheet is attached to the circuit surface to protect the circuit surface and fix the wafer, and the back surface is ground. Conventionally, a pressure-sensitive adhesive sheet obtained by coating a pressure-sensitive adhesive on a soft base material has been used for this purpose.
However, in a pressure-sensitive adhesive sheet using a soft base material, the tension applied during sticking accumulates as residual stress. When the wafer has a large diameter or is ground extremely thinly, the residual stress of the pressure-sensitive adhesive sheet is superior to the strength of the wafer, and the wafer is warped due to the force for eliminating the residual stress. Further, since the wafer is brittle after grinding, the soft base material sometimes breaks the wafer during transportation. Therefore, a method of fixing a wafer to a hard material such as a quartz plate or an acrylic plate and grinding the wafer is being studied.

To cut hard and brittle materials such as printer heads, glass / epoxy substrates, glass, and ceramics into small chips, these are fixed on a hard material and then cut. At this time, a double-sided adhesive sheet is used to fix the cut object on the hard material. However, it is extremely difficult to separate an object in which hard materials are pasted together with a conventional double-sided pressure-sensitive adhesive sheet, and when a brittle material such as a wafer is used, it is impossible to avoid destruction.

Therefore, there is a demand for the appearance of a double-sided pressure-sensitive adhesive sheet suitable for fixing semiconductor wafers and various above-mentioned objects to be cut on a hard material. Further, when processing a semiconductor wafer, a surface protection sheet is required for back grinding and an adhesive sheet for fixing the wafer is required for dicing, which is complicated in process control. Moreover, since the wafer is fragile, it may be damaged during transportation between such processes.

Therefore, there is a demand for the appearance of a process capable of performing such a series of steps of back surface grinding, dicing and carrying of a wafer in the same form, facilitating process control and preventing damage. The present invention has been made in view of the above conventional techniques, and an object thereof is to provide a double-sided pressure-sensitive adhesive sheet for processing a work piece with high accuracy and efficiency, and particularly, an ultrathin or large diameter. In the grinding of silicon wafers, the double-sided adhesive is suitable for the process in which the warp and the damage during transportation are reduced, so that the IC chips with high thickness accuracy can be produced with high yield and the back surface grinding and dicing can be performed in the same form. It is an object of the present invention to provide a highly reliable semiconductor manufacturing method using a sheet and the double-sided pressure-sensitive adhesive sheet.

[0006]

SUMMARY OF THE INVENTION A double-sided pressure-sensitive adhesive sheet according to the present invention comprises a shrinkable substrate, an energy ray-curable pressure-sensitive adhesive layer on one side of the substrate, and an elastic modulus at 120 ° C. of 5 × 10 ⁵ Pa on the opposite side. It is characterized in that a removable pressure-sensitive adhesive layer made of the following pressure-sensitive adhesive is provided. In the present invention, it is preferable that the adhesive force on the removable pressure-sensitive adhesive layer side is 5000 mN / 25 mm or less and the holding force is 50,000 sec or more. Further, the shrinkable base material is preferably provided with a large number of fine cuts. Such a double-sided pressure-sensitive adhesive sheet of the present invention is preferably used for temporarily holding an object to be processed on a hard plate and fixing or protecting it during the processing.

That is, in the double-sided pressure-sensitive adhesive sheet of the present invention, the work piece is attached to the energy ray-curable pressure-sensitive adhesive layer of the sheet, and the re-peelable pressure-sensitive adhesive layer is attached to the hard plate to be processed. Hold the object on a hard plate, process the work piece, irradiate the energy ray-curable pressure-sensitive adhesive layer with energy rays, shrink the shrinkable base material, and cure the resulting workpiece with energy rays. It is used in a series of steps of peeling from the mold adhesive layer.

Also in the above-mentioned method of use, the shrinkable substrate is preferably provided with a large number of fine cuts. In the above method of use, it is preferable that the object to be processed is a semiconductor wafer having a circuit pattern formed on its surface, and the processing is backside grinding of the wafer. Further, the object to be processed may be a semiconductor wafer having a circuit pattern formed on its surface, and the processing may be dicing into element pieces of the wafer.

Further, the workpiece is a semiconductor wafer having a circuit pattern formed on its surface, the processing is back grinding of the wafer and dicing of the wafer into element pieces, and the back grinding and dicing are performed in any order. May be performed in. According to such a double-sided pressure-sensitive adhesive sheet of the present invention, various kinds of workpieces can be temporarily held on a hard plate and fixed or protected during the processing, or required processing / protection. After performing, the work piece can be easily peeled off by a simple operation. Therefore, even when it is used for grinding the back surface of a semiconductor wafer having an extremely thin or large diameter, the accuracy of the thickness of the wafer is improved and the warp can be reduced. Further, damage during transportation can be prevented. Therefore, various electronic components, semiconductor chips, etc. can be manufactured with high yield.

Further, according to the present invention, since a series of steps such as processing and transportation can be performed in the same form, the step management becomes easy.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described more specifically with reference to the drawings. As shown in FIG. 1, the double-sided pressure-sensitive adhesive sheet 10 according to the present invention has a shrinkable base material 1, an energy ray-curable pressure-sensitive adhesive layer 2a provided on one surface of the base material, and an opposite surface of the base material. The removable pressure-sensitive adhesive layer 2b made of a pressure-sensitive adhesive having an elastic modulus at 120 ° C. of 5 × 10 ⁵ Pa or less is provided.

The shrinkable base material 1 is not particularly limited, but a heat shrinkable film is mainly used. The shrinkage rate of the shrinkable film used in the present invention is 10
˜90% is preferred, and more preferably 20-80%. Here, the shrinkage rate of the film is calculated from the dimension before shrinkage and the dimension after shrinkage based on the following mathematical formula.

[0013]

[Equation 1]

The shrinkage ratio is calculated based on the dimensions before and after heating the film to 120 ° C. As the shrinkable film as described above, various types are conventionally known, but in the present invention, any film can be used as long as it does not adversely affect the work piece such as ion contamination. it can. Specific examples thereof include uniaxially or biaxially stretched films such as polyethylene terephthalate, polyethylene, polystyrene, polypropylene, nylon, urethane, polyvinylidene chloride, and polyvinyl chloride.

The thickness of the shrinkable film as described above is usually 5 to 300 μm, preferably 10 to 200 μm.
Is. As the shrinkable film, it is particularly preferable to use a film of heat shrinkable polyethylene, polypropylene, polyethylene terephthalate or the like. The shrinkable film may be a single-layer product or a laminated product of the various shrinkable films described above. When it is a laminate, it is preferably a laminate of films having different shrinkage rates. When a laminate of films having different shrinkage rates is used as the base material 1, as shown in FIG. 5 and FIG. 10, it tends to be deformed into a convex shape on the side with a small shrinkage rate, and the work piece only attaches by point contact. Therefore, peeling becomes extremely easy.

Further, the shrinkable film used as the substrate 1 may be provided with a large number of fine cuts. The interval between the cuts (cut pitch) is determined according to the size of the individual workpiece, and is preferably 0.01 to 2 times the maximum length of the bottom surface of the workpiece, more preferably 0.1 to 1.
It is provided with a double pitch. Or the pitch is 0.
It may be 1 to 20 mm, more preferably 1 to 10 mm.

The shape of the cut is not particularly limited, and may be, for example, a lattice shape, a concentric circle shape, a radial shape, or a pattern shape in which these are combined, or may be randomly formed. The cut may be formed over the entire surface of the base material 1. When the double-sided pressure-sensitive adhesive sheet 10 of the present invention is used, as will be described later, the energy ray-curable pressure-sensitive adhesive layer is irradiated with energy rays after the required steps are completed, but when ultraviolet rays are used as energy rays. In order for all of the films constituting the substrate 1 to be transparent to ultraviolet rays.

The double-sided pressure-sensitive adhesive sheet 10 of the present invention is provided with an energy ray-curable pressure-sensitive adhesive layer 2a provided on one surface of the substrate 1. Energy ray curable adhesive
Generally, an acrylic pressure-sensitive adhesive and an energy ray-polymerizable compound are main components. Examples of the energy ray-polymerizable compound used in the energy ray-curable pressure-sensitive adhesive include tertiary irradiation by light irradiation as disclosed in JP-A-60-196,956 and JP-A-60-223,139. A low molecular weight compound having at least two photopolymerizable carbon-carbon double bonds in a molecule capable of forming a reticulated material is widely used. Acrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate,
Dipentaerythritol hexaacrylate or 1,4-butylene glycol diacrylate, 1,6-
Hexanediol diacrylate, polyethylene glycol diacrylate, commercially available oligoester acrylate, etc. are used.

Further, as the energy ray-polymerizable compound,
In addition to the acrylate compound as described above, a urethane acrylate oligomer can also be used. The urethane acrylate oligomer is a polyol compound such as polyester type or polyether type, and a polyvalent isocyanate compound such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-
A terminal isocyanate urethane prepolymer obtained by reacting xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc., with an acrylate or methacrylate having a hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl It is obtained by reacting methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate and the like.

The compounding ratio of the acrylic adhesive and the energy ray-polymerizable compound in the energy ray-curable adhesive is such that the energy ray-polymerizable compound is 50 to 200 parts by weight based on 100 parts by weight of the acrylic adhesive. It is desirable to be used in. In this case, the pressure-sensitive adhesive sheet obtained has a large initial adhesive strength, and the adhesive strength is greatly reduced after irradiation with energy rays. Therefore, peeling at the interface between the workpiece and the acrylic energy ray-curable pressure-sensitive adhesive layer is facilitated, and the workpiece can be picked up.

Further, the energy ray-curable pressure-sensitive adhesive layer 2a
May be formed from an energy ray-curable copolymer having an energy ray-polymerizable group in its side chain. Such an energy ray-curable copolymer has the property of having both tackiness and energy ray-curability. The energy ray-curable copolymer having an energy ray-polymerizable group in its side chain is disclosed in, for example, JP-A-5-32946 and JP-A-8-27.
The details are described in Japanese Patent No. 239, etc.

The acrylic energy ray-curable pressure-sensitive adhesive as described above has a sufficient adhesive force to the object to be processed before the energy ray irradiation, and the adhesive force remarkably decreases after the energy ray irradiation. That is, before irradiation with energy rays,
The work piece is held with a sufficient adhesive force, but the obtained work piece can be easily peeled off after irradiation with energy rays.

Further, the pressure-sensitive adhesive layer 2b on the other side, that is, the removable pressure-sensitive adhesive layer on the side to be attached to the hard plate is 120 ° C.
Can be formed by a removable pressure-sensitive adhesive layer made of a pressure-sensitive adhesive having an elastic modulus of 5 × 10 ⁵ Pa or less. When the value of the elastic modulus at 120 ° C. of the removable pressure-sensitive adhesive layer 2b is in such a range, the fluidity of the removable pressure-sensitive adhesive layer 2b is increased when the substrate 1 shrinks by heating, and the substrate 1 Does not impede the deformation of the energy ray-curable pressure-sensitive adhesive layer 2a due to the contraction of. Therefore, the surface of the energy ray-curable pressure-sensitive adhesive layer 2a is sufficiently deformed due to the shrinkage of the base material 1, and the contact with the work piece becomes a point contact to facilitate the peeling. Conversely, 120 ° C
When the value of the elastic modulus in is above this range, the removable pressure-sensitive adhesive layer 2b is hard to flow even when heated, and the deformation of the energy ray-curable pressure-sensitive adhesive layer 2a due to the shrinkage of the substrate 1 becomes small, It comes into surface contact with the work piece, making peeling difficult.

When it is desired to impart removability to the pressure-sensitive adhesive, it is customary that the pressure-sensitive adhesive has a high cohesive property and its elastic modulus is 10 ⁶ Pa or more even at 120 ° C. Further, in the case of an energy ray-curable pressure-sensitive adhesive, the elastic modulus after curing is further increased to 10 ⁷ Pa or more. On the other hand, the elastic modulus of the removable pressure-sensitive adhesive layer 2b in the present invention at 120 ° C. is 5 × 10 ⁵ Pa or less, preferably 5 × 10 ⁴ Pa to ³ × 10 ⁵ Pa.

Further, the removable pressure-sensitive adhesive layer 2 in the present invention
The adhesive strength of b is preferably 5000 mN / 25 mm or less, more preferably 500 to 4000 mN / 25 mm. The holding force is preferably 50,000 sec or more, more preferably 70,000 sec or more, and particularly preferably 70,000 sec in a non-creep (NC) state. Having such an adhesive property improves the removability of the double-sided adhesive sheet at room temperature. Therefore, when the double-sided pressure-sensitive adhesive sheet is peeled from the hard plate, the work can be performed without any problem, and since the pressure-sensitive adhesive does not remain on the hard plate, the number of times the hard plate is washed can be reduced.

As the adhesive having removability and having an elastic modulus at 120 ° C. of 5 × 10 ⁵ Pa or less, for example, an adhesive mainly composed of the following non-crosslinked or low-crosslinked acrylic copolymer is used. Agent. (1) A non-crosslinked or low-crosslinked acrylic copolymer having a large molecular weight (2) A narrow molecular weight distribution (in particular, a low molecular weight component is small)
Acrylic copolymer (3) Blend of non-crosslinked or low-crosslinked acrylic copolymer and crosslinked acrylic copolymer (4) Metal crosslinked acrylic copolymer As in the above (1) and (2) Since such a copolymer has a small proportion of low molecular weight components, it is easy to increase the holding power at room temperature, and by making it non-crosslinked or low crosslinked, the elastic modulus at high temperature can be lowered. Such a copolymer can be obtained by a polymerization method such as emulsion polymerization or suspension polymerization, which partially provides a high-concentration monomer composition. Further, in such a copolymer, the non-crosslinked or low-crosslinked acrylic copolymer as described above can be obtained by suppressing the generation of internal crosslinking or external crosslinking.

Since the double-sided pressure-sensitive adhesive sheet of the present invention is used in a semiconductor manufacturing process, it is preferable to use a nonionic type as an emulsifier in emulsion polymerization or a stabilizer in suspension polymerization. Further , the polymers obtained by these polymerization methods are generally said to have an ultra-high molecular weight, but the method for measuring the molecular weight in this region has not been established, so the value of the molecular weight may not be determined in some cases.

Further, in the blend as described in (3) above,
In a low temperature state, a non-crosslinked or low crosslinked acrylic copolymer component is incorporated into the crosslinked structure of the crosslinked acrylic copolymer, and the holding power at room temperature can be increased. In a high temperature state, the non-crosslinked or low-crosslinked acrylic copolymer component causes molecular motion beyond the suppression of the crosslinked structure, and the elastic modulus can be lowered.

Such a blend of copolymers is prepared by, for example, crosslinking a blend of an acrylic copolymer having a functional group involved in crosslinking and an acrylic copolymer having no functional group involved in crosslinking. It is obtained by doing. This cross-linking may be a cross-linking by an energy ray irradiation in which the functional group is an energy ray-polymerizable group. Further, the metal-crosslinked acrylic copolymer such as (4) has the weak binding force at high temperature, and thus the above physical properties can be obtained.

As the removable pressure-sensitive adhesive layer 2b of the double-sided pressure-sensitive adhesive sheet of the present invention, there may be a case where a pressure-sensitive adhesive which usually does not easily exhibit removability can be used. That is, if the pressure-sensitive adhesive has a removability with respect to the adherend of a specific material, the function of the re-peeling pressure-sensitive adhesive can be substantially achieved by using the plate of the material as the hard plate. The polymer component used in such a pressure-sensitive adhesive is not particularly limited, but for example, a rubber-based, acrylic-based, silicone-based, polyurethane-based, polyvinyl ether, or other polymer component is used.

The thickness of each of the pressure-sensitive adhesive layers 2a and 2b depends on the material thereof, but is usually about 3 to 100 μm,
It is preferably about 10 to 50 μm. The double-sided pressure-sensitive adhesive sheet 10 according to the present invention as described above is preferably used for protecting the surface of the semiconductor wafer during backside grinding and fixing the wafer. Further, the double-sided pressure-sensitive adhesive sheet 10 temporarily fixes a hard / brittle work piece such as a glass / epoxy base material, glass, or ceramics on the hard plate when processing (cutting) the work piece. Can also be used for As the hard plate, for example, a glass plate, a quartz plate, a plastic plate such as an acrylic plate, a polyvinyl chloride plate, a polyethylene terephthalate plate, a polypropylene plate, or a polycarbonate plate can be used. The hardness of the hard plate defined by ASTM D 883 is preferably 70 MPa or more. The thickness of the hard plate depends on its material, but normally,
It is about 0.1 to 10 mm. When ultraviolet rays are used as the energy rays, the hard plate is made of an ultraviolet-transparent material.

The method of using the double-sided pressure-sensitive adhesive sheet of the present invention will be described more specifically with reference to the drawings. First, as shown in FIG. 2, the work piece 3 is attached to the energy ray-curable pressure-sensitive adhesive layer 2 a of the double-sided pressure-sensitive adhesive sheet 10. The workpiece 3 is a semiconductor wafer as described above, a hard / brittle material such as a glass / epoxy base material, glass, or ceramics, various unprocessed electronic components, optical components, and the like, but is not limited thereto.

Then, as shown in FIG. 3, the removable pressure-sensitive adhesive layer 2b is attached to the hard plate 4 to hold the work piece 3 on the hard plate 4. The removable pressure-sensitive adhesive layer 2b may be attached to the hard plate, and then the work piece 3 may be attached to the energy ray-curable pressure-sensitive adhesive layer 2a. At this time, in order to prevent bubbles from entering between the removable pressure-sensitive adhesive layer 2b and the hard plate 4, it is preferable to attach the removable pressure-sensitive adhesive layer 2b and the hard plate 4 in a vacuum.

Next, required processing is performed on the workpiece 3. For semiconductor wafers, for example, backside grinding or dicing into small element pieces, and for glass / epoxy base materials, circuit formation and dicing into chips for each circuit. For glass, ceramics, etc., cutting or cutting. Perform processing such as etching. Further, at this time, the surfaces of the workpieces 3 on the side in contact with the pressure-sensitive adhesive layer 2a are simultaneously protected.

FIG. 4 shows, for example, a semiconductor wafer or a glass / epoxy substrate as the workpiece 3.
This is a state in which circuits are formed and dicing into chips for each circuit is performed. The dicing conditions are not particularly limited, but it is preferable to completely cut and separate the heat-shrinkable substrate 1. By being cut, the peeling area is reduced and the peeling time can be shortened. Further, the cut amount is preferably stopped at the removable pressure-sensitive adhesive layer 2b on the hard plate 4 side. If the hard plate 4 is not cut, the hard plate 4 can be reused many times.

Then, energy rays are irradiated from the hard plate 4 side to reduce the adhesive force of the energy ray-curable pressure-sensitive adhesive layer 2a, and the shrinkable base material 1 is shrunk by required means. For example, in the case of a heat-shrinkable base material, the base material 1 is shrunk by appropriate heating. As a result, as shown in FIG. 5, the contraction of the substrate 1 causes the shearing force generated between the obtained processed product 3 ′ and the energy ray-curable pressure-sensitive adhesive layer 2a to start peeling. The peeling of the processed product 3 ′ and the energy ray-curable pressure-sensitive adhesive layer 2a propagates from the periphery of the bonded portion to the central portion, and then the entire surface peels.

Further, as the releasable pressure-sensitive adhesive layer 2b is deformed as the substrate 1 shrinks, the double-sided pressure-sensitive adhesive sheet 10 is
It can also be easily removed from the hard plate 4. As described above, in the double-sided pressure-sensitive adhesive sheet of the present invention, the shrinkable base material 1 may be provided with a large number of fine cuts 6.
In this case, when the shrinkable base material 1 is shrunk by heating or the like after performing the required processing on the work piece 3, the energy ray-curable pressure-sensitive adhesive layer 2a is deformed in association with the shrinkable base material 1, and the work piece is processed. The contact area with 3'is reduced and the adhesive force is reduced (see FIG. 6). As a result, the double-sided pressure-sensitive adhesive sheet 10 can be more easily removed from the workpiece 3 '.

The double-sided pressure-sensitive adhesive sheet 10 of the present invention is particularly preferably used in the method for grinding the back surface of a semiconductor wafer, which comprises the following steps. That is, first, as shown in FIG. 7, the circuit surface of the semiconductor wafer 5 having a circuit pattern formed on the surface is attached to the energy ray-curable adhesive layer 2a of the double-sided adhesive sheet 10 of the present invention, and then the As shown in FIG. 8, the removable pressure-sensitive adhesive layer 2 b is attached to the hard plate 4 to hold the semiconductor wafer 5 on the hard plate 4.

In this state, the back surface of the semiconductor wafer 5 is ground to a predetermined thickness (see FIG. 9). Then, in the same manner as described above, irradiation with energy rays and contraction of the base material are performed, and the semiconductor wafer 5 is subjected to the energy ray-curable adhesive layer 2a.
From the surface (see FIG. 10). Further, the semiconductor wafer 5
After the back surface grinding, the wafer may be diced as shown in FIG. 4, and then the substrate may be shrunk by irradiation with energy rays. As a result, the back surface grinding and the dicing can be performed in the same form, which facilitates the process control, and since the wafers can be transferred between the processes while being held on the hard plate, the damage to the wafer can be prevented.

Further, in the present invention, contrary to the above,
After dicing the wafer, it is possible to grind the back surface of the element small piece while holding the element small piece on the hard plate.

[0041]

As described above, according to such a double-sided pressure-sensitive adhesive sheet of the present invention, various work pieces are temporarily held on a hard plate and fixed or protected during the processing. Or, after performing necessary processing and protection, the work piece can be easily peeled off by a simple operation. Therefore, even when it is used for grinding the back surface of a semiconductor wafer having an extremely thin or large diameter, the accuracy of the thickness of the wafer is improved and the warp can be reduced. Further, damage during transportation can be prevented. Therefore, various electronic components, semiconductor chips, etc. can be manufactured with high yield. Further, according to the present invention, a series of processes such as processing and transportation can be performed in the same form, so that process management becomes easy.

[0042]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0043]

Example 1 1-1 As an energy ray-curable adhesive layer, 100 parts by weight of an acrylic adhesive (copolymer of n-butyl acrylate and acrylic acid) and 200 parts by weight of a urethane acrylate oligomer having a molecular weight of 7,000. , An isocyanate cross-linking agent (addition product of trimethylolpropane and toluylene diisocyanate, hereinafter "TM-TD
I)) and an energy ray curing reaction initiator (1-hydroxycyclohexylbenzophenone)
Adhesive composition mixed with 10 parts by weight (modulus of elasticity at 25 ° C. after irradiation of ultraviolet rays of 1.5 × 10 ⁸ Pa, modulus of elasticity at 120 ° C. after curing of ultraviolet rays of 3.6 × 10 ⁷ Pa)
It was created. 1-2 Polyethylene terephthalate (PE) having a thickness of 25 μm, which is obtained by peeling the pressure-sensitive adhesive composition obtained in 1-1 above.
T) It was applied on the film so that the coating thickness after drying was 10 μm, and heated at 100 ° C. for 1 minute to form an energy ray-curable pressure-sensitive adhesive layer. Next, a heat-shrinkable polyethylene film (thickness: 35 μm, shrinkage ratio at 120 ° C .: 65
%) To obtain a single-sided pressure-sensitive adhesive sheet having an energy ray-curable pressure-sensitive adhesive layer. 1-3 Also, as a removable adhesive, 99 parts by weight of 2-ethylhexyl acrylate, 0.5 parts by weight of acrylic acid, 0.5 parts by weight of methacrylic acid and 3 parts by weight of a nonionic emulsifier made of nonylphenyl polyoxyethylene ether. A pressure-sensitive adhesive composition obtained by mixing 1.0 part by weight of an epoxy cross-linking agent with a removable pressure-sensitive adhesive that has been emulsion-polymerized in (a modulus of elasticity at 25 ° C. of 2.2 × 10 ⁵ Pa and a modulus of elasticity at 120 ° C. of 8 × 1).
0 ⁴ Pa) was prepared. 1-4 The coating composition after drying the pressure-sensitive adhesive composition of the above 1-3 on another PET film having a thickness of 25 μm that has been subjected to peeling treatment is 10
It was applied so as to have a thickness of μm, and heated at 100 ° C. for 1 minute to form a removable pressure-sensitive adhesive layer. 1-5 Laminate the heat-shrinkable polyethylene film side of the single-sided PSA sheet obtained in 1-2 to the removable adhesive layer on the PET film formed in 1-4 above to make a double-sided PSA sheet did.

The adhesive strength of this double-sided pressure-sensitive adhesive sheet on the removable pressure-sensitive adhesive layer side is 520 mN / 25 mm (measured according to JIS Z0237 with a glass plate used as a hard plate as an adherend), and the holding power is , 54000 seconds (JIS Z0237).

[0045]

[Example 2] An acrylic copolymer (weight average molecular weight: about 800,000) of 70 parts by weight of n-butyl acrylate and 30 parts by weight of 2-hydroxyethyl acrylate was used as the adhesive composition on the removable adhesive side. 100 parts by weight and an oligomer which is a homopolymer of n-butyl acrylate (weight average molecular weight:
About 3000) 50 parts by weight and cross-linking agent (TM-TDI)
The same operation as in Example 1 was performed except that 10 parts by weight of the formulation was used.

The elastic modulus of the removable adhesive is 25 ° C.
At 1.2 × 10 ⁶ Pa and 120 ° C. at 3.8
It was × 10 ⁵ Pa. The adhesive strength of the double-sided PSA sheet on the removable adhesive side is 2200 mN / 25 mm, and the holding force is 70000 sec / NC.
Met.

[0047]

Example 3 3-1 A pressure-sensitive adhesive composition on the removable pressure-sensitive adhesive side was prepared by using an acrylic copolymer (weight-average molecular weight: about 70 parts by weight of n-butyl acrylate and 30 parts by weight of 2-hydroxyethyl acrylate). 800,000) 100 parts by weight, n-butyl acrylate 70 parts by weight and 2-hydroxyethyl acrylate 30 parts by weight acrylic copolymer (weight average molecular weight: about 800,000) to 80 equivalents of mecryloyloxyethyl isocyanate. % Of 20% by weight of the energy ray-curable acrylic polymer and 1 part by weight of the energy ray-curing reaction initiator (1-hydroxycyclohexylbenzophenone) were mixed to prepare an adhesive composition. 3-2 The pressure-sensitive adhesive composition obtained in 3-1 above is applied to a 25 μm-thick PET film that has been subjected to a release treatment so as to have a thickness of 10 μm, heated at 100 ° C. for 1 minute, and then heat-shrinked. A polyethylene film (thickness: 30 μm, shrinkage at 120 ° C .: 40%) was attached. Then, from the heat-shrinkable polyethylene film side, a high pressure mercury lamp (120 W2 lamp,
Irradiation with ultraviolet rays at a line speed of 5 m / min) allows the removable pressure-sensitive adhesive layer (the elastic modulus at 25 ° C. to be 7.2 × 10 ⁶
Pa, elastic modulus at 120 ° C. is 1.8 × 10 ⁵ Pa)
A single-sided pressure-sensitive adhesive sheet having 3-3 The energy ray-curable pressure-sensitive adhesive composition obtained in the above 1-1 was applied onto a peel-treated PET film having a thickness of 25 μm so that the coating thickness after drying would be 10 μm.
It heated at 0 degreeC for 1 minute, and formed the energy-ray-curing type adhesive layer. 3-4 PET formed with the heat-shrinkable polyethylene film side of the single-sided pressure-sensitive adhesive sheet obtained in 3-2 above in 3-3 above
A double-sided pressure-sensitive adhesive sheet was prepared by bonding the film to the energy ray-curable pressure-sensitive adhesive layer on the film.

The adhesive strength of the double-sided pressure-sensitive adhesive sheet on the removable pressure-sensitive adhesive side was 1500 mN / 25 mm, and the holding force was 70,000 sec / NC.

[0049]

[Comparative Example 1] The energy ray-curable pressure-sensitive adhesive obtained in 1-1 was used in place of the pressure-sensitive adhesive composition of the removable pressure-sensitive adhesive, and the same operation as in Example 1 was carried out. A double-sided pressure-sensitive adhesive sheet provided with a line-curable pressure-sensitive adhesive layer was prepared. The adhesive strength of the double-sided adhesive sheet after UV curing is 120 mN /
It was 25 mm, and the holding power after UV curing could not be measured.

[0050]

Comparative Example 2 80 parts by weight of n-butyl acrylate and 2-hydroxyethyl acrylate 2 were prepared by using the removable pressure-sensitive adhesive composition.
100 parts by weight of an acrylic copolymer (weight average molecular weight: about 800,000) with 0 parts by weight, and a crosslinking agent (TM-TDI) 10
The same operation as in Example 1 except that the re-peelable pressure-sensitive adhesive composed of 10 parts by weight (the elastic modulus at 25 ° C. was 1.1 × 10 ⁶ Pa and the elastic modulus at 120 ° C. was 8.0 × 10 ⁵ Pa). I went.

The double-sided pressure-sensitive adhesive sheet had a removable pressure-sensitive adhesive side adhesive force of 2100 mN / 25 mm and a holding force of 70,000 sec / NC.
The double-sided PSA sheet obtained above was evaluated as follows. Evaluation Method The double-sided pressure-sensitive adhesive sheet was evaluated by taking as an example the case of applying it to a usage method of carrying after wafer grinding and dicing as described below.

With respect to a silicon wafer having a diameter of 6 inches and a thickness of 700 μm, the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples were peeled off the release film on only one side, and were stuck to the circuit forming surface of the silicon wafer. At this time, the energy ray-curable pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet is attached to the silicon wafer. Then, the other release film was peeled off, and the glass (20
It was attached to 0 mm × 200 mm, 1.15 mm thick).

After sticking, the wafer thickness is 100 μm, 50
The wafer was ground to a thickness of 30 μm. After grinding, it was conveyed to the dicing process as it was. The wafer ground above is a dicing machine (AWD-4000 manufactured by Tokyo Seimitsu Co., Ltd.)
Using B), the uncut amount from the bottom of the glass is 1.16 mm
Was cut and separated into 10 mm □ and 12 mm □. After cutting and separating, UV irradiation device from the glass side (Adwill manufactured by Lintec Co., Ltd.
RAD2000m / 8) was used to irradiate the sample with ultraviolet rays at a light intensity of 245 mJ / cm ² , and the sample was left for 1 minute on a hot plate heated to a surface temperature of 120 ° C. Suction pen from the top of the tip (made by Fluoromechanic, nib: 1.8 mm
φ) was used to pick up while changing the suction pressure, and the suction pressure at which pickup was possible was measured.

The results are shown in Table 1.

[0055]

[Table 1]

[Brief description of drawings]

FIG. 1 shows a cross-sectional view of a double-sided pressure-sensitive adhesive sheet according to the present invention.

FIG. 2 shows a state in which a work piece is attached to the double-sided pressure-sensitive adhesive sheet according to the present invention.

FIG. 3 shows a state in which a double-sided pressure-sensitive adhesive sheet to which a workpiece is attached is fixed on a hard plate.

FIG. 4 shows a state in which a work piece is processed.

FIG. 5 shows a state after energy ray irradiation and substrate contraction.

FIG. 6 shows an example of using a double-sided pressure-sensitive adhesive sheet in which a base material has cuts.

FIG. 7 shows a state in which a semiconductor wafer is attached to the double-sided pressure-sensitive adhesive sheet according to the present invention.

FIG. 8 shows a state in which a double-sided pressure-sensitive adhesive sheet having a semiconductor wafer attached thereto is fixed on a hard plate.

FIG. 9 shows a state in which the back surface of a semiconductor wafer is ground.

FIG. 10 shows a state after irradiation with energy rays and contraction of the substrate.

[Explanation of symbols]

1 ... Shrinkable substrate 2a ... Energy ray curable adhesive layer 2b ... Removable adhesive layer 3 ... Workpiece 3 '... processed product 4 ... Hard plate 5 ... Semiconductor wafer 10 ... Double-sided adhesive sheet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuyoshi Ebe             1375-19 Shimonoda, Shiraoka Town, Minami Saitama District, Saitama Prefecture (72) Inventor Katsuhiko Horimai             7-7-3 Tsuji, Saitama City, Saitama Prefecture             Ku Daini Urawa Dormitory 401 F-term (reference) 4J004 AA01 AA05 AA08 AA10 AA11                       AA14 AA17 AB01 AB06 CA04                       CA05 CA06 CC06 FA05 FA08                 4J040 CA001 DD051 DF001 EF001                       EF301 EK031 FA141 FA291                       JA09 JB07 JB09 NA20 PA23                       PA42

Claims (10)

[Claims] 1. A removability comprising a shrinkable substrate, an energy ray-curable pressure-sensitive adhesive layer on one surface of the substrate, and an adhesive having an elastic modulus at 120 ° C. of 5 × 10 ⁵ Pa or less on the opposite surface. A double-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer. 2. The adhesive force on the removable pressure-sensitive adhesive layer side is 5000 mN / 2.
The double-sided pressure-sensitive adhesive sheet according to claim 1, which has a holding power of 5 mm or less and a holding force of 50,000 sec or more. 3. The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the shrinkable substrate is provided with a large number of fine cuts. 4. The double-sided pressure-sensitive adhesive sheet according to claim 1, which is used for temporarily holding a work piece on a hard plate and fixing or protecting it during the work. 5. An energy ray-curable pressure-sensitive adhesive layer on one surface of the base material, and an elastic modulus at 120 ° C. of 5 × 10 5 on the opposite surface.
^While sticking the work piece to the energy ray-curable pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet provided with a removable pressure-sensitive adhesive layer made of a pressure-sensitive adhesive of ⁵ Pa or less, the removable pressure-sensitive adhesive layer on the hard plate. By sticking, holding the work piece on a hard plate, processing the work piece, irradiating the energy ray-curable pressure-sensitive adhesive layer with energy rays and shrinking the shrinkable substrate, A method for using a double-sided pressure-sensitive adhesive sheet, which comprises peeling the processed product from the energy ray-curable pressure-sensitive adhesive layer. 6. The adhesive force on the removable pressure-sensitive adhesive layer side is 5000 mN / 2.
The use of the double-sided pressure-sensitive adhesive sheet according to claim 5, wherein the double-sided pressure-sensitive adhesive sheet has a holding force of 5 mm or less and a holding force of 50,000 sec or more. 7. The method of using the double-sided pressure-sensitive adhesive sheet according to claim 5, wherein the shrinkable substrate is provided with a large number of fine cuts. 8. The double-sided product according to claim 5, wherein the object to be processed is a semiconductor wafer having a circuit pattern formed on its surface, and the processing is backside grinding of the wafer. How to use adhesive sheet. 9. The processing object is a semiconductor wafer having a circuit pattern formed on its surface, and the processing is dicing into element pieces of the wafer.
A method of using the double-sided PSA sheet according to any one of 1 to 7. 10. The object to be processed is a semiconductor wafer having a circuit pattern formed on the surface, the processing is back grinding of the wafer and dicing of the wafer into element pieces, and the back grinding and dicing are performed in an arbitrary order. The method for using the double-sided pressure-sensitive adhesive sheet according to claim 5, wherein the double-sided pressure-sensitive adhesive sheet is used.