JP7326248B2 - Adhesive tape and method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to an adhesive tape, and more specifically, an adhesive tape preferably used for temporarily fixing a semiconductor wafer or chip when manufacturing a semiconductor device by a so-called pre-dicing method, and a semiconductor using the adhesive tape. It relates to a method of manufacturing an apparatus.

As various electronic devices are becoming smaller and more multifunctional, semiconductor chips mounted on them are also required to be smaller and thinner. In order to make the chip thinner, it is common to grind the back surface of the semiconductor wafer to adjust the thickness. In addition, after forming grooves of a predetermined depth from the front side of the wafer, grinding is performed from the back side of the wafer, the bottom of the grooves is removed by grinding, the wafer is singulated, and chips are obtained by a method called a pre-dicing method. may also be used. In the pre-dicing method, since the back surface of the wafer can be ground and the wafer can be singulated at the same time, thin chips can be manufactured efficiently.

Conventionally, when grinding the back surface of a semiconductor wafer or manufacturing chips by the pre-dicing method, in order to protect the circuits on the wafer surface and to fix the semiconductor wafer and semiconductor chips, a back grind sheet is placed on the wafer surface. Adhesive tape is commonly applied.

As the back grind sheet used in the pre-dicing method, an adhesive tape comprising a substrate and an adhesive layer provided on one surface of the substrate is used. As an example of such an adhesive tape, Japanese Patent Application Laid-Open No. 2008-251934 (Patent Document 1) proposes an adhesive tape for semiconductor wafer processing, in which a radiation-curable adhesive layer is provided on a base film.

When the wafer is singulated by the pre-dicing method as described above, the back surface is ground while supplying water to the grinding surface in order to remove heat and grinding dust generated during grinding. However, it has been found that this conventional back-grinding leaves a grinding mark on the back surface of the chip and causes minute chipping at the edge of the chip, which impairs the chip's bending strength. did. In particular, as a result of the thinning of the chip, the chip becomes more susceptible to breakage, and a decrease in the bending strength is regarded as a problem.

JP 2008-251934 A

In order to remove the above-mentioned grinding marks and small chips of chips (hereinafter collectively referred to as "damaged parts"), after back grinding using water, water is finally used. It is being considered to remove the damaged portion by dry polishing to improve the die strength of the chip. However, since no water is used during dry polishing, the chips get hot. The heat of the chip propagates to the adhesive tape. As a result, the substrate temperature of the adhesive tape may reach 60° C. or higher during dry polishing.

Since the base material of the adhesive tape is formed from a resin film, it is easily deformed by heat. During back grinding, the adhesive tape is fixed by suction from the side of the base material of the adhesive tape, but the suction force may be insufficient at the ends of the adhesive tape. At this time, if the base material of the adhesive tape is deformed even slightly by heat, the adhesive tape may not be sufficiently fixed at the edge, and the edge of the adhesive tape may curl. As a result, the chips on the adhesive tape are peeled off. Chip detachment not only lowers the yield, but the detached chip may come into contact with other chips, damage other chips, damage the grinding equipment, and cause transport failures to the next process. .

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an adhesive tape capable of stably holding wafers, chips, and the like during processing of semiconductor wafers and the like. In particular, it is an object of the present invention to provide an adhesive tape capable of stably holding chips even when dry polishing is performed in the so-called pre-dicing method.

The gist of the present invention for the purpose of solving such problems is as follows.
(1) An adhesive tape comprising a substrate and an adhesive layer provided on one side thereof,
The pressure-sensitive adhesive tape, wherein the substrate has an absolute value of 60° C. TMA value of 30 μm or less.
(2) The pressure-sensitive adhesive tape according to (1), wherein the absolute value of the dimensional change after holding the substrate at 60° C. for 3 minutes is 0.8% or less.
(3) The tensile modulus of elasticity of the substrate at 23°C (E ₂₃ ) and the tensile modulus of elasticity at 60°C (
E ₆₀ ) and the elastic modulus change rate E _(23-60) of 30% or less.
(4) Grinding the back surface of the semiconductor wafer with grooves formed on the surface of the semiconductor wafer, and in the process of singulating the semiconductor wafer into semiconductor chips by grinding, it is attached to the surface of the semiconductor wafer and used. The pressure-sensitive adhesive tape according to any one of 1) to (3).
(5) The pressure-sensitive adhesive tape according to (4), including a step of performing dry polishing after singulating the semiconductor wafer into semiconductor chips.
(6) forming grooves from the surface side of the semiconductor wafer;
A step of attaching the adhesive tape according to any one of (1) to (4) above to the surface of the semiconductor wafer;
a step of grinding the semiconductor wafer having the adhesive tape attached to the front surface and having the grooves formed therein from the rear surface side to remove the bottoms of the grooves and singulate into a plurality of chips;
peeling off the adhesive tape from the plurality of chips;
A method of manufacturing a semiconductor device comprising:
(7) The method of manufacturing a semiconductor device according to (6), including a step of performing dry polishing after singulating the semiconductor wafer into semiconductor chips.

The pressure-sensitive adhesive tape according to the present invention can prevent curling during dry polishing by suppressing deformation of the base material due to heat to an extremely low level. Therefore, semiconductor chips can be manufactured with a high yield even by a pre-dicing method including a dry polishing process.
Moreover, since the adhesive tape of the present invention is suppressed in thermal deformation to an extremely low level, it can be used even in a normal back grinding process.

The adhesive tape according to the present invention will be specifically described below. First, major terms used in this specification will be explained.
In this specification, for example, "(meth)acrylate" is used as a term indicating both "acrylate" and "methacrylate", and the same applies to other similar terms.

The adhesive tape means a laminate including a base material and an adhesive layer provided on one side thereof, and may include other constituent layers. For example, a primer layer may be formed on the substrate surface on the adhesive layer side for the purpose of improving adhesion at the interface between the substrate surface and the adhesive layer and preventing migration of low-molecular-weight components. A release sheet may be laminated on the surface to protect the pressure-sensitive adhesive layer until use. Moreover, the base material may be a single layer or may be a multilayer. The same applies to the adhesive layer.
The "front surface" of a semiconductor wafer refers to the surface on which circuits are formed, and the "back surface" refers to the surface on which no circuits are formed.
Separation of a semiconductor wafer means dividing the semiconductor wafer into individual circuits to obtain semiconductor chips.

Dry polishing refers to a process of polishing with a polishing puff without using water or slurry of abrasive grains. As the polishing puff, various general-purpose polishing puffs are used, and commercially available polishing wheels such as Disco's "Gettering DP" and "DP08 SERIES" are used, but are not limited to these. Dry polishing removes the damaged portion of the chip, that is, the grinding marks and minute chips (chipping) of the chip.
The pre-dicing method refers to a method of forming grooves of a predetermined depth from the front surface of the wafer, grinding the back surface of the wafer, and dividing the wafer into individual pieces by grinding.

Next, the configuration of each member of the pressure-sensitive adhesive tape of the present invention will be described in more detail.
[Base material]
(Base material properties)
A film or sheet having an absolute value of 60° C. TMA value of 30 μm or less is used as the substrate of the adhesive tape.
The absolute value of the 60°C TMA value was measured using a measuring film of 15 mm (width) x 10 mm (length) made of the same material as the film or sheet composing the base material, using a BRUKER 4000SA, with a load of 2 g. The elongation or shrinkage of the film for measurement is measured at a temperature rate of 5°C/min (TMA value), and the absolute value at 60°C is referred to. Measurement conditions other than the above are set according to the operation manual of the measurement device. The TMA value is positive if the measuring film stretches and negative if it shrinks. In this specification, 10 or more samples are measured, the obtained TMA values are averaged, and evaluated as an absolute value.

The absolute value of the 60° C. TMA value is one index of the deformability of the base material at 60° C., and the lower the value, the more suppressed the deformation. Therefore, a base material having an absolute value of 60°C TMA value of 30 µm or less undergoes very little thermal deformation at 60°C. Polyvinyl chloride, which is widely used as a base material for adhesive tapes, has a thickness of about 40 μm, and ethylene/methacrylic acid copolymer has a thickness of about 220 μm.

When the absolute value of the 60° C. TMA value is 30 μm or less, deformation is suppressed even if the adhesive tape is heated to around 60° C. during dry polishing, and peeling of chips at the edge of the adhesive tape is reduced. Although not bound by any theory, the mechanism of manifestation of such effects is presumed as follows. The diameter of semiconductor wafers is increasing to 6 inches, 8 inches, and even 12 inches. A surplus region in which no circuit is formed is formed in the outer peripheral portion of the wafer. The adhesive tape attached to the circuit surface of the wafer during back grinding or pre-dicing has approximately the same size as the semiconductor wafer. If the absolute value of the 60° C. TMA value is within the above range and the adhesive tape has a relatively large area, the effect of thermal deformation of the base material is slight overall, so the edges of the adhesive tape curl slightly. However, the influence is limited to the surplus area and does not cause peeling or falling off of the product chip. In addition, deformation of the adhesive tape in the surplus area is small, and drop-off of discarded chips in the surplus area is reduced. On the other hand, when the absolute value of the 60° C. TMA value exceeds 30 μm, the curling of the adhesive tape due to thermal deformation of the base material extends to the circuit forming area, so many product chips and chips in the surplus area peel off and fall off, resulting in a decrease in yield. In addition, the peeled chips may come into contact with other chips and damage the other chips, damage the grinding machine, or cause defective transportation to the next process.

The absolute value of the 60° C. TMA value of the substrate is preferably between 5 and 25 μm. More preferably, it is 10 to 20 μm.

Although the absolute value of the 60° C. TMA value is preferably as low as possible, substrates with too low a TMA value tend to lack flexibility, so the above range is preferred. If the base material is excessively hard, the adhesiveness is poor, and pressure is applied to the circuit surface during back grinding, which may cause chipping or damage to the circuit or bump electrodes. However, if the film is sufficiently flexible, the absolute value of the 60° C. TMA value may be 5 μm or less, or may be 7 μm or less.

Also, the absolute value of the dimensional change rate after holding the substrate at 60° C. for 3 minutes is preferably 0.8% or less. The dimensional change rate is measured according to JIS C2151 and ASTM D1204, and the measurement temperature is 60° C. and the holding time is 3 minutes.

The dimensional change rate is measured using a measuring film of 10 cm×10 cm made of the same material as the film or sheet constituting the substrate. The dimensions of the measuring film are measured at 23°C. A sample for measurement is placed in a hot air circulating constant temperature bath at a predetermined temperature for a predetermined period of time. Then, after cooling to room temperature (23 ° C.), the following formula is obtained from the length of one side at 23 ° C. before heating (10 cm: L ₀ ) and the length of the same side at 23 ° C. after heating (L ₁ ) Calculate the dimensional change rate. In this specification, 10 or more samples are measured, the resulting dimensional change rates are averaged, and evaluated as an absolute value. In addition, the measured value uses the measured value of MD direction.
Dimensional change rate (%) = 100 x (L ₀ - L ₁ )/L ₀

The absolute value of the dimensional change rate at 60°C for 3 minutes is one index of the deformability of the base material at 60°C, and the lower the value, the more suppressed the deformation. Therefore, a base material having an absolute value of 0.8% or less of a dimensional change rate at 60°C for 3 minutes has very little thermal deformation at 60°C. Polyvinyl chloride, which is widely used as a base material for adhesive tapes, has a content of about 0.9%, and ethylene/methacrylic acid copolymer has a content of about 1%.

When the absolute value of the dimensional change rate at 60° C. for 3 minutes is 0.8% or less, deformation is suppressed even when the adhesive tape is heated to around 60° C. during dry polishing, and the chip peels off at the end of the adhesive tape. is reduced. Although not bound by any theory, the mechanism of manifestation of such an effect is similar to the above TMA value, because the effect of thermal deformation of the base material is generally slight, so that the end of the adhesive tape is slightly It is considered that even if the curling is to 100 degrees, the influence is limited to the surplus area, and the peeling and dropping of the product chip are not caused. In addition, deformation of the adhesive tape in the surplus area is small, and falling off of chips in the surplus area is reduced. On the other hand, when the absolute value of the dimensional change rate at 60°C for 3 minutes exceeds 0.8%, the curling of the adhesive tape due to thermal deformation of the base material extends to the circuit forming area, so the product chips and chips in the surplus area Not only do many chips peel off and fall off, which not only causes a decrease in yield, but also the peeled chips may come into contact with other chips and damage other chips, damage the grinding equipment, or transfer to the next process. It may cause defects.

The lower the absolute value of the dimensional change rate at 60° C. for 3 minutes, the better the results, and more preferably 0 to 0.5%. In another aspect of the invention, it may be 0.5 to 0.8%. The absolute value of the dimensional change rate of the substrate at 60° C. for 3 minutes is more preferably 0 to 0.2%, most preferably 0%.

Also, the thermal deformability of the base material can be evaluated by the change rate of the tensile elastic modulus at a predetermined temperature with respect to the tensile elastic modulus at room temperature. _{E ( 23- n)} (%) is obtained by 100×(E ₂₃ −E _n )/E ₂₃ .

The tensile modulus is measured by Rheovibron DDV-II-EP1 manufactured by Orientec using a measuring film of 15 mm (width) x 10 mm (length) made of the same material as the film or sheet constituting the base material. A value measured at a frequency of 11 Hz. In this specification, measurements are made on 10 or more samples, and the average value of the obtained tensile elastic moduli is used for evaluation.

In the substrate of the present invention, the elastic modulus change rate E _(23-60) obtained from the tensile elastic modulus (E ₂₃ ) at 23° C. and the tensile elastic modulus (E ₆₀ ) at 60° C. is preferably 30% or less. .

The elastic modulus change rate E _(23-60) is one of the indicators of the deformability of the base material at 60° C., and the lower the value, the more suppressed the deformation. Therefore, a substrate having a rate of change in elastic modulus E _(23-60) of 30% or less undergoes very little thermal deformation at 60°C. Polyvinyl chloride, which is widely used as a base material for adhesive tapes, has an elastic modulus change E _(23-60) of about 95%, and ethylene/methacrylic acid copolymer has about 70%.

When the elastic modulus change rate E _(23-60) is 30% or less, deformation is suppressed even when the adhesive tape is heated to around 60 ° C. during dry polishing, and peeling of chips at the end of the adhesive tape is reduced. . Although not bound by any theory, the mechanism of manifestation of such effects is presumed as follows. Heating of the substrate during dry polishing and shearing force applied to the tip during polishing may deform the substrate. In particular, when the elastic modulus of the base material is lowered by heating, it becomes susceptible to deformation, which may cause unpredictable deformation. However, if the rate of change in elastic modulus E _(23-60) is 30% or less, the characteristics at room temperature are substantially maintained, so it is considered that deformation due to temperature change is suppressed. On the other hand, if the rate of change in elastic modulus E _(23-60) exceeds 30%, the heating of the base material may significantly change the properties from those at room temperature, resulting in unpredictable deformation. As a result, the adhesive tape curls due to thermal deformation, and many product chips and chips in the surplus area are peeled off and dropped off. or damage the grinding equipment, or cause a failure in transportation to the next process.

The lower the elastic modulus change rate E _(23-60) , the better the results, and it is more preferably 25% or less, more preferably 20% or less. Although the lower limit is not particularly limited, it is 3% or more from the viewpoint of availability of materials.

Furthermore, the tensile modulus (E ₂₃ ) of the substrate at 23° C. is preferably 200-2000 MPa, more preferably 350-1500 MPa. Polyvinyl chloride, which is widely used as a base material for adhesive tapes, has a tensile modulus (E ₂₃ ) of about 450 MPa, and ethylene/methacrylic acid copolymer has a tensile modulus of about 110 MPa.

Furthermore, the tensile modulus (E ₆₀ ) of the substrate at 60° C. is preferably 150-1400 MPa, more preferably 300-1200 MPa. Polyvinyl chloride, which is widely used as a base material for adhesive tapes, has a tensile modulus (E ₆₀ ) of about 22 MPa, and ethylene/methacrylic acid copolymer has a tensile modulus of about 34 MPa.

(Non-limiting specific example)
The substrate of the present invention is not particularly limited as long as it satisfies the physical properties described above, and may be a resin film or sheet made of various materials. As for such a base material, a sheet having desired properties can be easily selected by subjecting various resin sheets to TMA measurement and, if necessary, dimensional change rate and elastic modulus measurement. Although one example of the base material of the present invention is described in detail below, these are merely descriptions for facilitating the availability of the base material and should not be construed as being limited in any way.

The substrate of the present invention may be, for example, a laminate of a first substrate made of a relatively hard resin film and a second substrate made of a relatively soft resin film. By forming a laminate of resin films having different properties, the properties can be easily controlled, and a substrate having desired properties can be easily obtained. Further, the substrate of the present invention may be a laminate composed of two layers of a first substrate and a second substrate, and further, the same or different second substrates are provided on both sides of the first substrate. A laminated body having a laminated three-layer structure may also be used.

(First base material)
The first substrate is preferably a rigid film having a Young's modulus of 1000 MPa or more, more preferably 1800 to 30000 MPa, still more preferably 2500 to 6000 MPa.
When a rigid film with a high Young's modulus is used as a constituent layer of the base material, the holding performance of the adhesive tape on the semiconductor wafer or semiconductor chip is enhanced, and by suppressing vibration during back grinding, chipping and damage to the semiconductor chip is prevented. easier to do. In addition, when the Young's modulus is within the above range, it is possible to reduce the stress when the adhesive tape is peeled off from the semiconductor chip, making it easier to prevent chip chipping and breakage that occur when the tape is peeled off. Furthermore, it is possible to improve the workability when attaching the adhesive tape to the semiconductor wafer.

Examples of rigid films having a Young's modulus of 1000 MPa or more include polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyesters, polyimides, polyamides, polycarbonates, polyacetals, modified polyphenylene oxides, polyphenylene sulfides, and polysulfones. , polyether ketone, and biaxially oriented polypropylene.
Among these resin films, a film containing one or more selected from a polyester film, a polyamide film, a polyimide film, and a biaxially stretched polypropylene film is preferable, more preferably a polyester film, and further preferably a polyethylene terephthalate film. .

The thickness (D1) of the first base material is preferably 500 μm or less, more preferably 15 to 350 μm, even more preferably 20 to 160 μm. By setting the thickness of the first base material to 500 μm or less, it becomes easier to adjust the peel force of the adhesive tape to the predetermined value described above. In addition, when the thickness is 15 μm or more, the base material can easily function as a support for the adhesive tape.

In addition, the first base material contains a plasticizer, a lubricant, an infrared absorbent, an ultraviolet absorbent, a filler, a coloring agent, an antistatic agent, an antioxidant, a catalyst, etc. within a range that does not impair the effects of the present invention. may Moreover, the first base material may be transparent or opaque, and may be colored or vapor-deposited as desired.
At least one surface of the first substrate may be subjected to an adhesion treatment such as corona treatment in order to improve adhesion to at least one of the second substrate and the pressure-sensitive adhesive layer. Further, the first substrate may have the resin film described above and an easy-adhesion layer coated on at least one surface of the resin film.

The easy-adhesion layer-forming composition for forming the easy-adhesion layer is not particularly limited, but examples thereof include compositions containing polyester-based resins, urethane-based resins, polyester-urethane-based resins, acrylic-based resins, and the like. The easily adhesive layer-forming composition may optionally contain a cross-linking agent, a photopolymerization initiator, an antioxidant, a softening agent (plasticizer), a filler, an antirust agent, a pigment, a dye, and the like. good.
The thickness of the easy-adhesion layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm. In addition, since the thickness of the easy-adhesion layer is smaller than the thickness of the first base material and the material is soft, the effect on Young's modulus is small, and the Young's modulus of the first base material is However, it is substantially the same as the Young's modulus of the resin film.

(Second base material)
The second base material is made of a relatively soft resin film, which reduces the vibration caused by grinding the semiconductor wafer and prevents the semiconductor wafer from cracking and chipping. In addition, the semiconductor wafer to which the adhesive tape is attached is placed on the suction table during backgrinding. of the adsorption table.
The second base material preferably has a storage modulus at 23° C. of 100 to 1500 MPa, more preferably 200 to 1200 MPa. Moreover, the stress relaxation rate of the second base material is preferably 70 to 100%, more preferably 78 to 98%.

The second base material has an elastic modulus and a stress relaxation rate within the above ranges, so that unevenness of fine foreign matter caught between the adhesive tape and the suction table and vibration and impact of the grindstone generated during back grinding are reduced. The effect of absorption by the second base material is enhanced.
The ratio (D2/D1) of the thickness (D2) of the second substrate to the thickness (D1) of the first substrate is preferably 0.7 or less. If the thickness ratio (D2/D1) is greater than 0.7, the proportion of the highly rigid portion of the adhesive tape decreases, making it difficult for the semiconductor wafer or semiconductor chip to be properly held by the base material. It becomes difficult to reduce time vibration. Therefore, when singulating into small and thin semiconductor chips by the pre-dicing method, even if an appropriate material for the second base material is selected, the semiconductor chips generated when singulating by back grinding It becomes difficult to prevent chips from chipping.
The thickness ratio (D2/D1) is preferably 0.10 to 0.70 in order to reduce chip chipping and make the second base material have an appropriate thickness to improve the cushioning performance of the adhesive tape. preferable.

The maximum value of tan δ of the dynamic viscoelasticity of the second base material at −5 to 120° C. (hereinafter also simply referred to as “maximum value of tan δ”) is preferably 0.7 or more, more preferably 0.8 or more, It is more preferably 1.0 or more. Although the upper limit of the maximum value of tan δ is not particularly limited, it is usually 2.0.
If the maximum value of tan δ of the second base material is 0.7 or more, the second base material is more effective in absorbing the vibration and impact of the grindstone that occur during back grinding. Therefore, in the pre-dicing method, even if a semiconductor wafer or individualized semiconductor chips are ground to an extremely thin thickness, chipping at the corners of the chips can be easily prevented.
Note that tan δ is called the loss tangent, defined as "loss modulus/storage modulus", and is a value measured by the response to stress such as tensile stress and torsional stress applied to the object by a dynamic viscoelasticity measuring device. is.

The thickness (D2) of the second substrate is preferably 8-80 μm, more preferably 10-60 μm. By setting the thickness of the second base material to 8 μm or more, the second base material can appropriately absorb vibrations during back grinding. Further, when the thickness is 80 μm or less, it becomes easier to adjust the thickness ratio (D2/D1) to the above value. Further, when the base material is a laminate having a three-layer structure in which the same or different second base material is laminated on both sides of the first base material, the thickness (D2) of the second base material is preferably 35 μm. or less, more preferably 30 μm or less. In the three-layer structure laminate, the physical properties of the relatively soft second substrate may be dominant, but by setting the thickness of the second substrate in the above range, the desired 60 ° C. TMA value, It becomes easier to adjust the dimensional change rate.

The second substrate may be formed from a soft film such as low-density polyethylene, but is preferably a layer formed from a second substrate-forming composition containing an energy ray-polymerizable compound. Since the second base material contains the energy ray polymerizable compound, it can be cured by being irradiated with the energy ray. The term "energy ray" refers to ultraviolet rays, electron beams, etc., and preferably ultraviolet rays are used.
Further, more specifically, the composition for forming the second base material includes a urethane (meth)acrylate (a1) and a polymerizable compound (a2) having an alicyclic or heterocyclic group having 6 to 20 ring atoms. is preferably included. By containing these two components, the composition for forming the second base material can easily set the elastic modulus of the second base material, the stress relaxation rate of the second base material, and the maximum value of tan δ within the ranges described above. From these points of view, the second base material-forming composition more preferably contains a polymerizable compound (a3) having a functional group in addition to the components (a1) and (a2).
In addition, the composition for forming the second base material further preferably contains a photopolymerization initiator in addition to the above components (a1) and (a2) or (a1) to (a3), and the effect of the present invention is obtained. Other additives and resin components may be contained as long as they do not impair the composition.
Each component contained in the composition for forming the second base material will be described in detail below.

(Urethane (meth)acrylate (a1))
The urethane (meth)acrylate (a1) is a compound having at least a (meth)acryloyl group and a urethane bond, and has the property of being polymerized and cured by energy ray irradiation. Urethane (meth)acrylates (a1) are oligomers or polymers.

The weight average molecular weight (Mw) of component (a1) is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, still more preferably 3,000 to 20,000. The mass average molecular weight (Mw) is a polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method, and specifically measured under the following conditions.
(Measurement condition)
・ Column: "TSK guard column HXL-H""TSK gel GMHXL (x 2)""TSK gel G2000HXL" (both manufactured by Tosoh Corporation)
・Column temperature: 40°C
・Developing solvent: tetrahydrofuran ・Flow rate: 1.0 mL/min
The number of (meth)acryloyl groups (hereinafter also referred to as "number of functional groups") in component (a1) may be monofunctional, difunctional, or trifunctional or more, but monofunctional or difunctional is preferred. .
Component (a1) can be obtained, for example, by reacting a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound and a polyvalent isocyanate compound with a (meth)acrylate having a hydroxyl group. In addition, you may use a component (a1) individually or in combination of 2 or more types.

The polyol compound used as the raw material of component (a1) is not particularly limited as long as it is a compound having two or more hydroxy groups. Specific polyol compounds include, for example, alkylene diols, polyether polyols, polyester polyols, and polycarbonate polyols. Among these, polyester type polyols are preferred.
The polyol compound may be a bifunctional diol, a trifunctional triol, or a tetrafunctional or higher polyol, preferably a bifunctional diol, and more preferably a polyester type diol.

Examples of polyvalent isocyanate compounds include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; Alicyclic diisocyanates such as ,4'-diisocyanate, ω,ω'-diisocyanatedimethylcyclohexane;4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, naphthalene- aromatic diisocyanates such as 1,5-diisocyanate;
Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferred.

A urethane (meth)acrylate (a1) can be obtained by reacting a terminal isocyanate urethane prepolymer obtained by reacting the above polyol compound with a polyvalent isocyanate compound with a (meth)acrylate having a hydroxyl group. The (meth)acrylate having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group and a (meth)acryloyl group in at least one molecule.

Specific (meth)acrylates having a hydroxy group include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth) Acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, etc. hydroxyalkyl (meth)acrylate; hydroxy group-containing (meth)acrylamide such as N-methylol (meth)acrylamide; vinyl alcohol, vinylphenol, reaction obtained by reacting diglycidyl ester of bisphenol A with (meth)acrylic acid things, etc.
Among these, hydroxyalkyl (meth)acrylates are preferred, and 2-hydroxyethyl (meth)acrylate is more preferred.

The conditions for reacting the isocyanate-terminated urethane prepolymer and the (meth)acrylate having a hydroxy group are preferably conditions for reacting at 60 to 100° C. for 1 to 4 hours in the presence of a solvent and a catalyst added as necessary. .
The content of the component (a1) in the composition for forming the second substrate is preferably 10 to 70% by mass, more preferably 20% by mass, based on the total amount (100% by mass) of the composition for forming the second substrate. ~60% by mass, more preferably 25 to 55% by mass, even more preferably 30 to 50% by mass.

(Polymerizable compound (a2) having an alicyclic or heterocyclic group having 6 to 20 ring atoms)
Component (a2) is a polymerizable compound having an alicyclic or heterocyclic group with 6 to 20 ring atoms, preferably a compound having at least one (meth)acryloyl group. By using this component (a2), the film formability of the obtained composition for forming the second substrate can be improved.

The number of ring-forming atoms in the alicyclic group or heterocyclic group of component (a2) is preferably 6 to 20, more preferably 6 to 18, still more preferably 6 to 16, and particularly preferably 7 to 12. be. Atoms forming the ring structure of the heterocyclic group include, for example, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom and the like.
The number of ring-forming atoms refers to the number of atoms constituting the ring itself of a compound having a structure in which atoms are cyclically bonded, and atoms that do not constitute a ring (for example, hydrogen atoms bonded to atoms that constitute a ring). Also, when the ring is substituted with a substituent, the atoms included in the substituent are not included in the number of ring-forming atoms.

Examples of specific component (a2) include isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, alicyclic group-containing (meth)acrylates such as adamantane (meth)acrylate; heterocyclic group-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and morpholine (meth)acrylate; and the like.
In addition, you may use a component (a2) individually or in combination of 2 or more types.
Among these, alicyclic group-containing (meth)acrylates are preferred, and isobornyl (meth)acrylates are more preferred.

The content of the component (a2) in the composition for forming the second substrate is preferably 10 to 70% by mass, more preferably 20% by mass, based on the total amount (100% by mass) of the composition for forming the second substrate. to 60% by mass, more preferably 25 to 55% by mass, particularly preferably 30 to 50% by mass.

(Polymerizable compound (a3) having a functional group)
Component (a3) is a polymerizable compound containing a functional group such as a hydroxyl group, an epoxy group, an amide group, or an amino group, and further preferably a compound having at least one (meth)acryloyl group.
Component (a3) has good compatibility with component (a1), and facilitates adjustment of the viscosity of the composition for forming the second base material within an appropriate range. In addition, when the component (a3) is contained, the elastic modulus and tan δ values of the second substrate formed from the composition can be easily set within the above ranges, and the cushioning performance can be maintained even if the second substrate is relatively thin. get better.
Examples of component (a3) include hydroxyl group-containing (meth)acrylates, epoxy group-containing compounds, amide group-containing compounds, and amino group-containing (meth)acrylates.

Examples of hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxy Butyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenylhydroxypropyl (meth)acrylate and the like.
Examples of epoxy group-containing compounds include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, allyl glycidyl ether, and the like. Among these, epoxy groups such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate Group-containing (meth)acrylates are preferred.
Examples of amide group-containing compounds include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N -Methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide and the like.
Examples of amino group-containing (meth)acrylates include primary amino group-containing (meth)acrylates, secondary amino group-containing (meth)acrylates, and tertiary amino group-containing (meth)acrylates.

Among these, hydroxyl group-containing (meth)acrylates are preferable, and hydroxyl group-containing (meth)acrylates having an aromatic ring such as phenylhydroxypropyl (meth)acrylate are more preferable.
In addition, you may use a component (a3) individually or in combination of 2 or more types.

The content of the component (a3) in the composition for forming the second base material makes it easy to set the elastic modulus and the stress relaxation rate of the second base material within the ranges described above, and the content of the composition for forming the second base material is In order to improve film properties, it is preferably 5 to 40% by mass, more preferably 7 to 35% by mass, still more preferably 10 to 30% by mass, based on the total amount (100% by mass) of the composition for forming the second substrate. % by weight, particularly preferably 13 to 25% by weight.
In addition, the content ratio [(a2)/(a3)] of the component (a2) and the component (a3) in the composition for forming the second base material is preferably 0.5 to 3.0, more preferably 1.0 to 3.0, more preferably 1.3 to 3.0, particularly preferably 1.5 to 2.8.

(Polymerizable compounds other than components (a1) to (a3))
The composition for forming the second substrate may contain polymerizable compounds other than the components (a1) to (a3) as long as the effects of the present invention are not impaired.
Other polymerizable compounds include, for example, alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms; styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, N-vinylcaprolactam Vinyl compounds such as: and the like. In addition, you may use these other polymerizable compounds individually or in combination of 2 or more types.

The content of the other polymerizable compound in the composition for forming the second substrate is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, particularly preferably 0 ~2% by mass.

(Photoinitiator)
The composition for forming the second base material may further contain a photopolymerization initiator from the viewpoint of shortening the polymerization time by light irradiation and reducing the amount of light irradiation when forming the second base material. preferable.
Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. Specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyrolnitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and the like.
These photopolymerization initiators can be used alone or in combination of two or more.
The content of the photopolymerization initiator in the composition for forming the second base material is preferably 0.05 to 15 parts by mass, more preferably 0.1, with respect to 100 parts by mass of the total amount of the energy ray-polymerizable compounds. to 10 parts by mass, more preferably 0.3 to 5 parts by mass.

(Other additives)
The composition for forming the second base material may contain other additives as long as the effects of the present invention are not impaired. Other additives include, for example, antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, and the like. When these additives are blended, the content of each additive in the composition for forming the second base material is preferably 0.01 to 6 mass parts with respect to 100 mass parts of the total amount of the energy ray-polymerizable compounds. parts, more preferably 0.1 to 3 parts by mass.

(resin component)
The composition for forming the second base material may contain a resin component as long as the effects of the present invention are not impaired. Examples of the resin component include polyene-thiol resins, polyolefin resins such as polybutene, polybutadiene and polymethylpentene, and thermoplastic resins such as styrene copolymers.
The content of these resin components in the composition for forming the second substrate is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, even more preferably 0 to 5% by mass, and particularly preferably 0 to 5% by mass. It is 2% by mass.
(Preparation of base material)
A non-limiting example of the base material of the pressure-sensitive adhesive tape of the present invention is a laminate of the first base material and the second base material. The production method is not particularly limited and can be produced by a known method.
For example, the second base material provided by coating and curing the composition for forming the second base material on the release sheet is directly bonded to the first base material, and the release sheet is removed to obtain the laminated base material. is obtained.
As a method for forming the second substrate on the release sheet, the composition for forming the second substrate is directly applied on the release sheet by a known coating method to form a coating film, and the coating film is coated with The second base material can be formed by irradiating the energy beam. Alternatively, the second base material may be formed by directly applying the composition for forming the second base material on one side of the first base material, and drying it by heating or irradiating the coating film with energy rays.

Examples of the method of applying the composition for forming the second substrate include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating. . Moreover, in order to improve coating properties, an organic solvent may be added to the composition for forming the second base material, and the composition may be applied in the form of a solution onto the release sheet.

When the composition for forming the second base material contains an energy ray-polymerizable compound, the coating film of the composition for forming the second base material is cured by irradiation with an energy ray to form the second base material. is preferred. Curing of the second base material may be performed in a single curing process, or may be performed in a plurality of times. For example, the coating film on the release sheet may be completely cured to form the second base material, and then the second base material may be attached to the first base material. After forming a base material forming film and bonding the second base material forming film to the first base material, the second base material may be formed by irradiating energy rays again to completely cure the film. Ultraviolet rays are preferable as the energy rays to be irradiated in the curing treatment. When curing, the coating film of the composition for forming the second substrate may be exposed, but the coating film is covered with a release sheet or the first substrate, and the energy beam is applied in a state where the coating film is not exposed. It is preferable to irradiate and cure.

Furthermore, the base material can be obtained by laminating the second base material on one side or both sides of the first base material. In addition to the first and second base materials, the base material of the present invention may have other constituent layers as long as the predetermined 60° C. TMA value is satisfied.

The total thickness of the base material is the total thickness of the first base material, the second base material and other constituent layers that may be used as necessary, and is preferably 23 to 150 μm, more preferably 30 to 140 μm.
The laminated base material, which is an example of the base material of the present invention, is a laminate of a first base material and a second base material, and its physical properties are controlled by the materials and thicknesses of the first base material and the second base material. can. Therefore, in order to obtain a base material with desired properties, it is important to balance the properties of the first base material and the second base material according to the following guidelines.

The 60° C. TMA value, dimensional change rate, and elastic modulus change rate of the substrate can be controlled by appropriately selecting the film constituting the substrate. For example, these values can be lowered by using a film having a relatively high Tg as the constituent film or by performing an annealing treatment during film formation of the substrate. Similarly, when the base material is a laminated base material of the first base material and the second base material, the first base material or the second base material, or both of them may be a high Tg film or an annealed film. By configuring with, the 60° C. TMA value, the dimensional change rate, and the elastic modulus change rate can be controlled within a low range. Furthermore, in the case of a laminated substrate, by increasing the relative thickness of the high Tg film or the annealed film, the 60 ° C. TMA value, the dimensional change rate, and the elastic modulus change rate can be controlled within a low range. . When other constituent layers are used, the 60° C. TMA value, dimensional change rate, and elastic modulus change rate can be controlled within a low range by using a film with relatively high rigidity.

[Adhesive layer]
The pressure-sensitive adhesive is not particularly limited as long as it has appropriate pressure-sensitive adhesiveness at room temperature, but preferably has a storage modulus of 0.05 to 0.50 MPa at 23°C. Circuits and the like are formed on the surface of a semiconductor wafer, and the surface is usually uneven. When the adhesive tape has a storage elastic modulus within the above range, when it is attached to an uneven wafer surface, the unevenness of the wafer surface and the adhesive layer are sufficiently contacted, and the adhesiveness of the adhesive layer is improved. It is possible to make it work properly. Therefore, it is possible to reliably fix the adhesive tape to the semiconductor wafer and to appropriately protect the wafer surface during back grinding. From these points of view, the storage elastic modulus of the adhesive is more preferably 0.10 to 0.35 MPa. The storage elastic modulus of the adhesive means the storage elastic modulus before curing by energy ray irradiation when the adhesive layer is formed from an energy ray-curable adhesive.

The thickness (D3) of the pressure-sensitive adhesive layer is preferably less than 200 μm, more preferably 5-55 μm, even more preferably 10-50 μm. When the pressure-sensitive adhesive layer is made thin in this way, the proportion of the low-rigidity portion of the pressure-sensitive adhesive tape can be reduced, so chipping of the semiconductor chip that occurs during back-grinding can be more easily prevented.

The adhesive layer is formed of, for example, an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, or the like, with the acrylic adhesive being preferred.
Moreover, the adhesive layer is preferably formed from an energy ray-curable adhesive. By forming the pressure-sensitive adhesive layer from an energy ray-curable pressure-sensitive adhesive, the elastic modulus at 23° C. is set within the above range before curing by energy ray irradiation, while the peel force after curing is 1000 mN/50 mm. You can easily set the following.

Specific examples of the adhesive are described in detail below, but these are non-limiting examples, and the adhesive layer in the present invention should not be construed as being limited to these.
As the energy ray-curable adhesive, for example, in addition to a non-energy ray-curable adhesive resin (also referred to as "adhesive resin I"), an energy ray-curable adhesive containing an energy ray-curable compound other than the adhesive resin agent composition (hereinafter also referred to as "X-type adhesive composition") can be used. As the energy ray-curable adhesive, an energy ray-curable adhesive resin (hereinafter also referred to as "adhesive resin II") obtained by introducing an unsaturated group into the side chain of a non-energy ray-curable adhesive resin is used. A pressure-sensitive adhesive composition (hereinafter, also referred to as "Y-type pressure-sensitive adhesive composition") containing as a main component and not containing an energy ray-curable compound other than the pressure-sensitive adhesive resin may also be used.

Furthermore, as the energy ray-curable adhesive, a combined type of X-type and Y-type, that is, in addition to the energy ray-curable adhesive resin II, an energy ray-curable adhesive containing an energy ray-curable compound other than the adhesive resin is used. An adhesive composition (hereinafter also referred to as "XY type adhesive composition") may be used.
Among these, it is preferable to use the XY type adhesive composition. By using the XY type, it is possible to have sufficient adhesive properties before curing, while sufficiently reducing the peeling force to the semiconductor wafer after curing.

However, the adhesive may be formed from a non-energy ray-curable adhesive composition that does not cure even when irradiated with energy. The non-energy ray-curable adhesive composition contains at least the non-energy ray-curable adhesive resin I, but does not contain the energy ray-curable adhesive resin II and the energy ray-curable compound. be.

In the following description, the term "adhesive resin" is used as a term indicating one or both of the above-described adhesive resin I and adhesive resin II. Examples of specific adhesive resins include acrylic resins, urethane resins, rubber resins, and silicone resins, with acrylic resins being preferred.
The acrylic pressure-sensitive adhesive in which an acrylic resin is used as the pressure-sensitive adhesive resin will be described in more detail below.

An acrylic polymer (b) is used as the acrylic resin. The acrylic polymer (b) is obtained by polymerizing a monomer containing at least an alkyl (meth)acrylate, and contains structural units derived from the alkyl (meth)acrylate. Alkyl (meth)acrylates include those having 1 to 20 carbon atoms in the alkyl group, and the alkyl group may be linear or branched. Specific examples of alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) methacrylate, 2-ethylhexyl (meth) ) acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate and the like. You may use an alkyl (meth)acrylate individually or in combination of 2 or more types.

Moreover, from the viewpoint of improving the adhesive strength of the pressure-sensitive adhesive layer, the acrylic polymer (b) preferably contains structural units derived from alkyl (meth)acrylates in which the alkyl group has 4 or more carbon atoms. The number of carbon atoms in the alkyl (meth)acrylate is preferably 4-12, more preferably 4-6. In addition, the alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms is preferably an alkyl acrylate.

In the acrylic polymer (b), the alkyl (meth)acrylate whose alkyl group has 4 or more carbon atoms is the total amount of the monomers constituting the acrylic polymer (b) (hereinafter simply referred to as "monomer total amount"). , preferably 40 to 98% by mass, more preferably 45 to 95% by mass, still more preferably 50 to 90% by mass.

In the acrylic polymer (b), in addition to structural units derived from an alkyl (meth)acrylate in which the alkyl group has 4 or more carbon atoms, an alkyl group is added to adjust the elastic modulus and adhesive properties of the pressure-sensitive adhesive layer. A copolymer containing a structural unit derived from an alkyl (meth)acrylate having 1 to 3 carbon atoms is preferred. The alkyl (meth)acrylate is preferably an alkyl (meth)acrylate having 1 or 2 carbon atoms, more preferably methyl (meth)acrylate, and most preferably methyl methacrylate. In the acrylic polymer (b), the alkyl (meth)acrylate having 1 to 3 carbon atoms in the alkyl group is preferably 1 to 30% by mass, more preferably 3 to 26% by mass, based on the total amount of the monomer, More preferably, it is 6 to 22% by mass.

The acrylic polymer (b) preferably has structural units derived from a functional group-containing monomer in addition to the structural units derived from the alkyl (meth)acrylate described above. The functional group of the functional group-containing monomer includes a hydroxyl group, a carboxyl group, an amino group, an epoxy group and the like. The functional group-containing monomer reacts with a cross-linking agent described later to become a cross-linking starting point, or reacts with an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the acrylic polymer (b). is possible.

Functional group-containing monomers include hydroxyl group-containing monomers, carboxy group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, and the like. These monomers may be used alone or in combination of two or more. Among these, hydroxyl group-containing monomers and carboxy group-containing monomers are preferable, and hydroxyl group-containing monomers are more preferable.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, ) hydroxyalkyl (meth)acrylates such as acrylate and 4-hydroxybutyl (meth)acrylate; and unsaturated alcohols such as vinyl alcohol and allyl alcohol.

Carboxy group-containing monomers include, for example, ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and citraconic acid, and their anhydrides. , 2-carboxyethyl methacrylate and the like.

The functional group monomer is preferably 1 to 35% by mass, more preferably 3 to 32% by mass, still more preferably 6 to 30% by mass, based on the total amount of monomers constituting the acrylic polymer (b).
In addition to the above, the acrylic polymer (b) may be derived from monomers copolymerizable with the above acrylic monomers, such as styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide. It may contain structural units.

The acrylic polymer (b) can be used as a non-energy ray-curable adhesive resin I (acrylic resin). The energy ray-curable acrylic resin is obtained by reacting the functional group of the acrylic polymer (b) with a compound having a photopolymerizable unsaturated group (also referred to as an unsaturated group-containing compound). mentioned.

The unsaturated group-containing compound is a compound having both a substituent bondable to the functional group of the acrylic polymer (b) and a photopolymerizable unsaturated group. Examples of the photopolymerizable unsaturated group include a (meth)acryloyl group, a vinyl group, and an allyl group, with the (meth)acryloyl group being preferred.
Moreover, an isocyanate group, a glycidyl group, etc. are mentioned as a functional group and a bondable substituent which the unsaturated group containing compound has. Accordingly, examples of unsaturated group-containing compounds include (meth)acryloyloxyethyl isocyanate, (meth)acryloylisocyanate, glycidyl (meth)acrylate, and the like.

Further, the unsaturated group-containing compound preferably reacts with a part of the functional groups of the acrylic polymer (b). %, more preferably 55 to 93 mol %, of the unsaturated group-containing compound. Thus, in the energy ray-curable acrylic resin, part of the functional groups remain without reacting with the unsaturated group-containing compound, thereby facilitating cross-linking with a cross-linking agent.
The weight average molecular weight (Mw) of the acrylic resin is preferably 300,000 to 1,600,000, more preferably 400,000 to 1,400,000, and still more preferably 500,000 to 1,200,000.

(Energy ray-curable compound)
As the energy ray-curable compound contained in the X-type or XY-type pressure-sensitive adhesive composition, a monomer or oligomer having an unsaturated group in the molecule and capable of being polymerized and cured by energy ray irradiation is preferable.
Examples of such energy ray-curable compounds include trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4- Polyvalent (meth)acrylate monomers such as butylene glycol di(meth)acrylate, 1,6-hexanediol (meth)acrylate, urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, epoxy ( Oligomers such as meth)acrylates can be mentioned.

Among these, urethane (meth)acrylate oligomers are preferable because they have relatively high molecular weights and are less likely to lower the elastic modulus of the pressure-sensitive adhesive layer.
The energy ray-curable compound has a molecular weight (weight average molecular weight in the case of an oligomer) of preferably 100 to 12,000, more preferably 200 to 10,000, even more preferably 400 to 8,000, and particularly preferably 600 to 6,000.

The content of the energy ray-curable compound in the X-type adhesive composition is preferably 40 to 200 parts by mass, more preferably 50 to 150 parts by mass, still more preferably 60 to 100 parts by mass with respect to 100 parts by mass of the adhesive resin. 90 parts by mass.
On the other hand, the content of the energy ray-curable compound in the XY-type adhesive composition is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 100 parts by mass of the adhesive resin. is 3 to 15 parts by mass. In the XY-type adhesive composition, since the adhesive resin is energy ray-curable, even if the content of the energy ray-curable compound is small, it is possible to sufficiently reduce the peel strength after energy ray irradiation. is.

(crosslinking agent)
The pressure-sensitive adhesive composition preferably further contains a cross-linking agent. The cross-linking agent cross-links the adhesive resins by reacting, for example, with the functional groups derived from the functional group monomers of the adhesive resins. Examples of cross-linking agents include isocyanate-based cross-linking agents such as tolylene diisocyanate, hexamethylene diisocyanate, and adducts thereof; ethylene glycol glycidyl ether, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane. epoxy-based cross-linking agents such as hexa[1-(2-methyl)-aziridinyl]triphosphatriazine; aziridine-based cross-linking agents such as hexa[1-(2-methyl)-aziridinyl]triphosphatriazine; These cross-linking agents may be used alone or in combination of two or more.

Among these, isocyanate-based cross-linking agents are preferable from the viewpoints of increasing cohesive strength and improving adhesive strength, and from the viewpoints of availability and the like.
From the viewpoint of promoting the cross-linking reaction, the amount of the cross-linking agent is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and still more preferably 0 parts by mass with respect to 100 parts by mass of the adhesive resin. 0.05 to 4 parts by mass.

(Photoinitiator)
Moreover, when the pressure-sensitive adhesive composition is energy ray-curable, the pressure-sensitive adhesive composition preferably further contains a photopolymerization initiator. By including a photopolymerization initiator, the curing reaction of the pressure-sensitive adhesive composition can sufficiently proceed even with relatively low-energy energy rays such as ultraviolet rays.

Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. Specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyrolnitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and the like.

You may use these photoinitiators individually or in combination of 2 or more types.
The amount of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and still more preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the adhesive resin. is.

(Other additives)
The pressure-sensitive adhesive composition may contain other additives as long as the effects of the present invention are not impaired. Other additives include, for example, antistatic agents, antioxidants, tackifiers, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, and the like. When these additives are blended, the blending amount of the additives is preferably 0.01 to 6 parts by mass with respect to 100 parts by mass of the adhesive resin.

In addition, from the viewpoint of improving the applicability to the base material or the release sheet, the pressure-sensitive adhesive composition may be further diluted with an organic solvent to form a solution of the pressure-sensitive adhesive composition.
Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol and isopropanol.
As these organic solvents, the organic solvent used in the synthesis of the adhesive resin may be used as it is, or the organic solvent other than the organic solvent used in the synthesis may be used so that the solution of the adhesive composition can be uniformly applied. may be added with one or more organic solvents.

[Release sheet]
A release sheet may be attached to the surface of the adhesive tape. Specifically, the release sheet is attached to the surface of the adhesive layer of the adhesive tape. The release sheet is attached to the surface of the adhesive layer to protect the adhesive layer during transportation and storage. The release sheet is releasably attached to the adhesive tape, and is peeled off and removed from the adhesive tape before the adhesive tape is used (that is, before wafer backgrinding).
As the release sheet, a release sheet having at least one surface subjected to a release treatment is used, and specific examples include a release sheet base material coated with a release agent on the surface thereof.

As the substrate for the release sheet, a resin film is preferable, and as the resin constituting the resin film, for example, polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polypropylene resin, polyethylene resin, etc. and the like polyolefin resins. Examples of release agents include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, fluorine-based resins, and the like.
The thickness of the release sheet is not particularly limited, but is preferably 10-200 μm, more preferably 20-150 μm.

(Method for producing adhesive tape)
The method for producing the pressure-sensitive adhesive tape of the present invention is not particularly limited, and it can be produced by a known method.
For example, a pressure-sensitive adhesive layer provided on a release sheet can be adhered to one side of a substrate to produce an adhesive tape in which the release sheet is adhered to the surface of the pressure-sensitive adhesive layer. The release sheet attached to the surface of the pressure-sensitive adhesive layer may be peeled off and removed before use of the pressure-sensitive adhesive tape.
As a method for forming the adhesive layer on the release sheet, the adhesive composition is directly coated on the release sheet by a known coating method, and then heated and dried to volatilize the solvent from the coating film. agent layer can be formed.

Alternatively, the pressure-sensitive adhesive layer may be formed by directly applying the pressure-sensitive adhesive (pressure-sensitive adhesive composition) to one side of the substrate. As the method of applying the adhesive, the spin coating method, the spray coating method, the bar coating method, the knife coating method, the roll coating method, the blade coating method, the die coating method, the gravure coating method, etc. shown in the manufacturing method of the second base material. is mentioned.

The pressure-sensitive adhesive layer may be provided on the surface of the first base material constituting the base material, or may be provided on the surface of the second base material. It is preferably provided on the surface of the first base material. When the pressure-sensitive adhesive layer is provided on the surface of the first base material, the second base material side is placed on a suction table used during back grinding. Since the second base material is relatively soft, it can easily adhere to the suction table and prevent the adhesive tape from curling.

[Method for manufacturing a semiconductor device]
The pressure-sensitive adhesive tape of the present invention is particularly preferably used in the pre-dicing method, when it is attached to the front surface of a semiconductor wafer and the back surface of the wafer is ground. As a non-limiting example of use of the adhesive tape, a method for manufacturing a semiconductor device will be described in more detail below.

Specifically, the method for manufacturing a semiconductor device includes at least steps 1 to 4 below.
Step 1: Step of forming grooves from the surface side of the semiconductor wafer Step 2: Step of sticking the adhesive tape to the surface of the semiconductor wafer Step 3: The semiconductor with the adhesive tape stuck on the surface and the grooves formed above The wafer is ground from the back side to remove the bottom of the groove and singulated into a plurality of chips Step 4: From the singulated semiconductor wafer (that is, a plurality of semiconductor chips), the adhesive tape is removed. peeling process

Hereinafter, each step of the method for manufacturing the semiconductor device will be described in detail.
(Step 1)
In step 1, grooves are formed from the surface side of the semiconductor wafer.
The grooves formed in this process are shallower than the thickness of the semiconductor wafer. The grooves can be formed by dicing using a conventionally known wafer dicing device or the like. The semiconductor wafer is divided into a plurality of semiconductor chips along the grooves by removing the bottoms of the grooves in step 3, which will be described later.
(Step 2)
In step 2, the pressure-sensitive adhesive tape of the present invention is attached via the pressure-sensitive adhesive layer to the surface of the semiconductor wafer on which the grooves are formed.

The semiconductor wafer used in this manufacturing method may be a silicon wafer, a gallium/arsenic wafer, a glass wafer, or a sapphire wafer. Although the thickness of the semiconductor wafer before grinding is not particularly limited, it is usually about 500 to 1000 μm. A semiconductor wafer usually has a circuit formed on its surface. Formation of circuits on the wafer surface can be carried out by various methods including conventionally used methods such as etching, lift-off and blade methods.

The semiconductor wafer to which the adhesive tape is applied and the grooves are formed is placed on the suction table, and is held by the suction table by suction. At this time, the semiconductor wafer is sucked with its surface side arranged on the table side.

(Step 3)
After steps 1 and 2, the back surface of the semiconductor wafer on the suction table is ground to singulate the semiconductor wafer into a plurality of semiconductor chips.
Here, when grooves are formed in the semiconductor wafer, the back surface grinding is performed so as to thin the semiconductor wafer at least to the position reaching the bottom of the groove. By this back-grinding, the grooves become cuts penetrating the wafer, and the semiconductor wafer is divided by the cuts into individual semiconductor chips.

The shape of the individualized semiconductor chips may be a square or an elongated shape such as a rectangle. Although the thickness of the individualized semiconductor chips is not particularly limited, it is preferably about 5 to 100 μm, more preferably 10 to 45 μm. The size of the individualized semiconductor chips is not particularly limited, but the chip size is preferably less than 50 mm ² , more preferably less than 30 mm ² , and even more preferably less than 10 mm ² .

When the adhesive tape of the present invention is used, even with such a thin and/or small semiconductor chip, chipping occurs in the semiconductor chip during back grinding (step 3) and during peeling of the adhesive tape (step 4). is prevented.
After the backside grinding is finished, dry polishing is preferably performed prior to picking up the chip.

Grinding the back surface of the chip leaves a grinding mark on the back surface of the chip, and small chips (chipping) occur at the edge of the chip. As a result of thinning and miniaturization of the chip, the chip is easily damaged, and a decrease in the bending strength is regarded as a problem. In order to remove the above-mentioned grinding marks and minute chips (damaged parts) of the chip, after back grinding, the damaged parts are finally removed by dry polishing without using water to improve the chip's bending strength. is preferred. Since no water is used during dry polishing, the chips get hot. The heat of the chip propagates to the adhesive tape. As a result, during dry polishing, the temperature of the substrate reaches 60° C. or higher, and the end of the adhesive tape may curl and the chip may peel off. However, by using the adhesive tape of the present invention, the deformation of the adhesive tape can be suppressed and the peeling of the chip can be reduced. Therefore, the adhesive tape of the present invention is particularly suitable for holding semiconductor wafers and chips in a pre-dicing method including a dry polishing process.

(Step 4)
Next, the adhesive tape for semiconductor processing is peeled off from the individualized semiconductor wafer (that is, a plurality of semiconductor chips). This step is performed, for example, by the following method.
First, when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape is formed from an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive layer is cured by irradiation with energy rays. Next, a pick-up tape is attached to the rear surface side of the separated semiconductor wafer, and the position and direction are aligned so that pick-up is possible. At this time, the ring frame arranged on the outer peripheral side of the wafer is also adhered to the pick-up tape, and the outer peripheral edge of the pick-up tape is fixed to the ring frame. The wafer and the ring frame may be attached to the pickup tape at the same time, or may be attached at separate timings. Next, the adhesive tape is peeled off from the plurality of semiconductor chips fixed on the pickup tape.

After that, a plurality of semiconductor chips on the pickup tape are picked up and fixed on a substrate or the like to manufacture a semiconductor device.
The pickup tape is not particularly limited, but is composed of, for example, a base material and an adhesive sheet having an adhesive layer provided on one surface of the base material.

Adhesive tape can also be used instead of the pickup tape. The adhesive tape includes a laminate of a film-like adhesive and a release sheet, a laminate of a dicing tape and a film-like adhesive, and an adhesive layer and a release sheet that function as both a dicing tape and a die bonding tape. A dicing die bonding tape and the like can be mentioned. Also, before applying the pickup tape, a film-like adhesive may be applied to the back side of the semiconductor wafer that has been divided into individual pieces. When a film adhesive is used, the film adhesive may have the same shape as the wafer.

In the case of using an adhesive tape or in the case of attaching a film adhesive to the back side of the semiconductor wafer that has been singulated before attaching the pick-up tape, the plurality of semiconductor chips on the adhesive tape or the pick-up tape is a semiconductor. It is picked up together with the adhesive layer divided into the same shape as the chip. Then, the semiconductor chip is fixed on a substrate or the like via an adhesive layer to manufacture a semiconductor device. The division of the adhesive layer is performed by laser or expansion.

As described above, the adhesive tape of the present invention is mainly used in a method for singulating semiconductor wafers by the pre-dicing method, but the adhesive tape of the present invention can also be used for normal back grinding. It can also be used to temporarily fix a workpiece during processing of glass, ceramics, etc. It can also be used as various removable adhesive tapes.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

The measuring method and evaluation method in the present invention are as follows.
[TMA value]
A measuring film of 15 mm (width)×10 mm (length) made of the same material as the film or sheet constituting the substrate is prepared. Measure the elongation or shrinkage of the film for measurement (TMA value) with a BRUKER 4000SA under a load of 2 g and a heating rate of 5°C/min. Measurement conditions other than the above are set according to the operation manual of the measurement device. Ten samples are measured, and the average value of the obtained TMA values is calculated.
[Dimensional change rate]
A 10 cm×10 cm measurement film made of the same material as the film or sheet constituting the substrate is prepared. The dimensions of the measuring film are measured at 23°C. A sample for measurement is placed on a heating table at 60° C. for 3 minutes. Then, after cooling to room temperature (23 ° C.), the following formula is obtained from the length of one side at 23 ° C. before heating (10 cm: L ₀ ) and the length of the same side at 23 ° C. after heating (L ₁ ) Calculate the dimensional change rate. The average value of the dimensional change rate obtained by measuring 10 samples is calculated. In addition, the measured value uses the measured value of MD direction.
Dimensional change rate (%) = 100 x (L ₀ - L ₁ )/L ₀

[Tensile modulus]
A measuring film of 15 mm (width)×10 mm (length) made of the same material as the film or sheet constituting the substrate is prepared. Using a dynamic viscoelasticity device (manufactured by Orientec, trade name "Rheovibron DDV-II-EP1"), the tensile modulus of the film for measurement was measured at a frequency of 11 Hz and in a temperature range of -20 to 150 ° C. for 10 samples. It was measured.
The average value of the tensile elastic modulus at 23 ° C. is E ₂₃ , the average value of the tensile elastic modulus at 60 ° C. is E ₆₀ , and the change rate of the tensile elastic modulus from 23 ° C. to 60 ° C. E _(23-60) (% ).

[Young's modulus of first base material]
The Young's modulus of the first substrate was measured according to JISK-7127 (1999) at a test speed of 200 mm/min.

[Elastic modulus of second base material and maximum value of tan δ]
Instead of the first substrate, a release sheet (manufactured by Lintec Corporation, trade name “SP-PET381031”, thickness: 38 μm) was used, and the thickness of the second substrate obtained was 200 μm. A second substrate for testing was produced in the same manner as the second substrates of Examples and Comparative Examples, which will be described later. After removing the release sheet on the second substrate for testing, using a test piece cut into a predetermined size, a dynamic viscoelasticity device (manufactured by Orientec, trade name "Rheovibron DDV-II-EP1") At a frequency of 11 Hz, the loss modulus and storage modulus were measured in a temperature range of -20 to 150°C. The value of "loss modulus/storage modulus" at each temperature is calculated as tan δ at that temperature, and the maximum value of tan δ in the range of -5 to 120°C is referred to as the "maximum value of tan δ of the second substrate". did.

[Stress relaxation rate of the second base material]
A second substrate for testing was prepared on a release sheet in the same manner as described above, and cut into a size of 15 mm×140 mm to form a sample. Using a universal tensile tester (Autograph AG-10kNIS manufactured by SHIMADZU), both ends of this sample were grabbed at 20 mm and pulled at a speed of 200 mm per minute, and the stress A (N/m ² ) when stretched 10%, The stress B (N/m ² ) was measured one minute after the tape stopped stretching. From the values of these stresses A and B, (AB)/A×100 (%) was calculated as the stress relaxation rate.

[Peeling evaluation]
The adhesive tapes with release sheets obtained in Examples and Comparative Examples are set in a tape laminator (manufactured by Lintec Co., Ltd., trade name "RAD-3510") while peeling off the release sheet, and grooves are formed on the wafer surface by a pre-dicing method. It was attached to the formed 12-inch silicon wafer (thickness: 760 μm) under the following conditions.
Roll height: 0 mm Roll temperature: 23°C (room temperature)
Table temperature: 23°C (room temperature)
The obtained silicon wafer with the adhesive tape was cut into pieces having a thickness of 30 μm and a chip size of 1 mm square by back grinding (pre-dicing method).
After finishing the back grinding, the ground surface was polished with DPG8760 manufactured by Disco. As the polishing wheel, "Gettering DP" manufactured by Disco was used. Damaged portions (grinding marks, chipping) of the chips were removed by this polishing.
After completion of dry polishing, the presence or absence of deformation at the end of the adhesive tape and the number of chips held at the end of the adhesive tape were checked. Deformation of the adhesive tape end was evaluated based on the distance between the adhesive tape and the suction table. If there was a gap between the adhesive tape and the suction table, it was judged as defective. In addition, the group of chips held on the adhesive tape was observed, and if a peeled chip was found, it was regarded as defective.

All parts by mass in the following examples and comparative examples are solid content values.

[Example 1]
(1) First Substrate A 50 μm-thick polyethylene terephthalate film (Young's modulus: 2500 MPa) was prepared as the first substrate.

(2) Second substrate (synthesis of urethane acrylate oligomer)
A terminal isocyanate urethane prepolymer obtained by reacting a polyester diol and isophorone diisocyanate is reacted with 2-hydroxyethyl acrylate to obtain a bifunctional urethane acrylate oligomer (UA-1) having a mass average molecular weight (Mw) of 5000. got

(Preparation of composition for forming second base material)
40 parts by mass of the urethane acrylate oligomer (UA-1) synthesized above, 40 parts by mass of isobornyl acrylate (IBXA), and 20 parts by mass of phenylhydroxypropyl acrylate (HPPA) are blended, and further a photopolymerization initiator. 2.0 parts by mass of 1-hydroxycyclohexylphenyl ketone (manufactured by BASF, product name “Irgacure 184”) and 0.2 parts by mass of a phthalocyanine pigment were blended to prepare a composition for forming the second substrate.

(3) Laminated base material The composition for forming the second base material obtained above is applied to one surface of the first base material, and ultraviolet light is applied under the conditions of an illuminance of 160 mW/cm ² and a dose of 500 mJ/cm ² . The composition for forming the second substrate was cured by irradiation to obtain a laminated substrate having a second substrate having a thickness of 30 μm on the first substrate.

(4) Preparation of adhesive composition Acrylic polymer obtained by copolymerizing 65 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 15 parts by mass of 2-hydroxyethyl acrylate (2HEA) (b) is reacted with 2-methacryloyloxyethyl isocyanate (MOI) so as to be added to 80 mol% of all hydroxyl groups of the acrylic polymer (b) to obtain an energy ray-curable acrylic resin. (Mw: 500,000).

To 100 parts by mass of this energy ray-curable acrylic resin, 6 parts by weight of polyfunctional urethane acrylate (trade name: Shikoh UT-4332, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), which is an energy ray-curable compound, and an isocyanate-based cross-linking agent. (manufactured by Tosoh Corporation, product name: Coronate L) was added in an amount of 0.375 parts by mass based on the solid content, and 1 part by weight of a photopolymerization initiator composed of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide was added. , to prepare a coating solution of the pressure-sensitive adhesive composition by diluting with a solvent.

(5) Preparation of adhesive tape On the release-treated surface of a release sheet (manufactured by Lintec Corporation, trade name: SP-PET381031), the coating liquid of the adhesive composition obtained above is dried to a thickness of 20 μm. and dried by heating to form an adhesive layer on the release sheet. This pressure-sensitive adhesive layer was attached to the surface of the first base material of the laminated base material to obtain a pressure-sensitive adhesive tape with a release sheet.
The storage elastic modulus of the pressure-sensitive adhesive layer at 23°C was 0.15 MPa. The second substrate had a storage modulus of 250 MPa at 23° C., a stress relaxation rate of 90%, and a maximum value of tan δ of 1.24.

[Example 2]
A pressure-sensitive adhesive tape was prepared in the same manner as in Example 1, except that a composite film (thickness: 80 μm) of 27.5 μm low-density polyethylene/25 μm polyethylene terephthalate/27.5 μm low-density polyethylene was used as the substrate instead of the laminated substrate. got

[Comparative Example 1]
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1, except that a commercially available polyvinyl chloride film (thickness: 80 µm) was used as the base material instead of the laminated base material.

[Comparative Example 2]
In the same manner as in Example 1, except that an ethylene/methacrylic acid copolymer film (thickness: 80 μm), Nucrel (registered trademark: Mitsui DuPont Polychemical), was used as the base material instead of the laminated base material. Got the sticky tape.

The properties of the substrates used in Examples and Comparative Examples were evaluated, and the respective adhesive tapes were used to evaluate peeling. Table 1 shows the results.

From the above results, it can be seen that when the absolute value of the 60° C. TMA value is 30 μm or less, the adhesive tape does not deform even when dry polishing is performed, and the chip can be held well. In addition, in addition to the adhesive tapes described in detail in the examples and comparative examples, tests using various adhesive tapes confirmed that good results can be obtained if the absolute value of the 60 ° C. TMA value is 30 μm or less. . Similarly, the absolute value of the dimensional change rate at 60 ° C. for 3 minutes and the elastic modulus change rate E _(23-60) (%) were 0.8% or less and 30% or less, respectively, by tests using various adhesive tapes. It was confirmed that better results could be obtained if

Claims (6)

An adhesive tape used by being attached to the surface of a semiconductor wafer in a process of grinding the back surface of a semiconductor wafer having grooves formed on the surface of the semiconductor wafer and singulating the semiconductor wafer into semiconductor chips by grinding. ,
Including a base material and an adhesive layer provided on one side thereof,
The base material is a laminate composed of two layers of a first base material and a second base material,
The first base material has a Young's modulus of 1000 MPa or more,
The pressure-sensitive adhesive tape, wherein the substrate has an absolute value of 60° C. TMA value of 30 μm or less. 2. The pressure-sensitive adhesive tape according to claim 1, wherein the absolute value of the dimensional change after holding the substrate at 60[deg.] C. for 3 minutes is 0.8% or less. 3. The elastic modulus change rate E _(23-60) obtained from the tensile elastic modulus (E ₂₃ ) at 23° C. and the tensile elastic modulus (E ₆₀ ) at 60° C. of the base material is 30% or less. The adhesive tape described in . 2. The pressure-sensitive adhesive tape according to claim 1 , further comprising a step of performing dry polishing after singulating the semiconductor wafer into semiconductor chips. a step of forming grooves from the surface side of the semiconductor wafer;
A step of attaching the adhesive tape according to any one of claims 1 to 3 to the surface of the semiconductor wafer;
a step of grinding the semiconductor wafer having the adhesive tape attached to the surface and having the grooves formed thereon from the rear surface side to remove the bottoms of the grooves and singulate into a plurality of chips;
peeling off the adhesive tape from the plurality of chips;
A method of manufacturing a semiconductor device comprising: 6. The method of manufacturing a semiconductor device according to claim 5 , further comprising the step of performing dry polishing after singulating said semiconductor wafer into semiconductor chips.