Method for manufacturing semiconductor device

Abstract

The present invention relates to a method for manufacturing a semiconductor device, the method comprising the following steps in this order: step 1 including a support grinding process for grinding a support adhered to the double-sided adhesive sheet; step 1: a step for producing a laminate having a support, a double-sided adhesive sheet, and an object to be processed in this order; step 2: a step for grinding the object to be processed in a state in which the support of the laminate is fixed.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a semiconductor device. Background Art

[0002] As information terminal devices are rapidly becoming thinner, smaller, and more multifunctional, semiconductor devices mounted in these devices are also being required to be thinner and more dense.

[0003] In the method for manufacturing a semiconductor device, back grinding of a semiconductor wafer is performed. Back grinding of a semiconductor wafer is usually performed with an adhesive sheet for back grinding attached to the circuit surface of the semiconductor wafer to protect the circuit surface, and after processing, the adhesive sheet is peeled off from the surface of the semiconductor wafer.

[0004] In addition, a double-sided adhesive sheet is sometimes used as an adhesive sheet for back grinding, and back grinding is performed in a state where a support is attached to the surface opposite to the semiconductor wafer. In this way, by fixing the semiconductor wafer to the support via the double-sided adhesive sheet, vibration, misalignment, breakage, etc. can be suppressed when grinding the semiconductor wafer and when transporting the ground semiconductor wafer or the semiconductor chips obtained by singulation.

[0005] As important performance required for back grinding of semiconductor wafers, for example, the thickness accuracy of the ground semiconductor wafer can be cited. In particular, in recent years, due to the high integration achieved by stacking multiple semiconductor chips, even if the thickness deviation of each semiconductor chip is small, the semiconductor device obtained by stacking them may have a large thickness deviation. Therefore, for semiconductor wafers after back grinding, higher thickness uniformity is increasingly required than before.

[0006] Patent document 1 discloses a temporary fixing tape, which is used as a temporary fixing tape for grinding a substrate, and has a supporting base material and an adhesive layer laminated on one side of the supporting base material, wherein the supporting base material has a first layer supporting the above-mentioned base material, and a second layer located between the first layer and the above-mentioned adhesive layer and having a buffering property, and when the above-mentioned substrate having a protrusion on at least one surface is joined to the above-mentioned adhesive layer, the front end of the above-mentioned protrusion penetrates the above-mentioned adhesive layer and is located in the above-mentioned second layer, and when the adhesive strength of the above-mentioned adhesive layer after irradiation with the above-mentioned energy rays is set to F1 [N / 25mm] and the adhesive strength of the above-mentioned second layer is set to F2 [N / 25mm], the relationship F1>F2 is satisfied.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2020-77799 Summary of the invention

[0010] Problems to be solved by the invention

[0011] The temporary fixing tape of Patent Document 1 is an invention that solves the problem of thickness variation after grinding caused by protrusions when grinding a substrate having protrusions on the surface thereof, by using a support base material having a specific layer structure.

[0012] However, the thickness uniformity of the object after grinding is affected by various factors, in addition to the unevenness of the object, such as the thickness deviation of the adhesive sheet attached to the object, the uneven pressure when attaching the object, the support, etc. to the adhesive sheet, etc. With the technology of Patent Document 1, it is difficult to suppress the thickness deviation after grinding caused by factors other than the unevenness of the object.

[0013] The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide a method for manufacturing a semiconductor device in which the thickness uniformity of a grinding object is excellent.

[0014] Solutions to the problem

[0015] The present inventors have conducted intensive studies and have found that the above-mentioned problems can be solved by the following invention, thereby completing the following present invention.

[0016] That is, the present invention relates to the following [1] to

[13] .

[0017] [1] A method for manufacturing a semiconductor device, comprising the following steps 1 and 2 in sequence:

[0018] Step 1: a step of producing a laminate having a support, a double-sided adhesive sheet, and an object to be processed in this order,

[0019] Step 2: a step of grinding the object to be processed while the support of the stack is fixed.

[0020] The step 1 includes a support grinding process of grinding the support adhered to the double-sided adhesive sheet.

[0021] [2] The method for manufacturing a semiconductor device as described in [1] above, wherein the support body grinding process is a process of grinding the support body adhered to the other side of the double-sided adhesive sheet while the processing object adhered to one side of the double-sided adhesive sheet is fixed.

[0022] [3] The method for manufacturing a semiconductor device according to [1] or [2] above, wherein the support is one or more selected from a silicon wafer and a glass wafer.

[0023] [4] The method for manufacturing a semiconductor device according to any one of [1] to [3] above, wherein the thickness of the support body after the support body grinding process is 200 to 1,500 μm.

[0024] [5] The method for manufacturing a semiconductor device according to any one of [1] to [4] above, wherein the support has a laminated structure including a support layer and a peelable sheet laminated on one side of the support layer,

[0025] The support is attached to the double-sided adhesive sheet in such a manner that the removable sheet becomes the outermost surface.

[0026] The support grinding treatment is a step of grinding the releasable sheet.

[0027] [6] The method for manufacturing a semiconductor device according to [5] above, wherein the support layer is one or more selected from a silicon wafer and a glass wafer.

[0028] [7] The method for producing a semiconductor device according to any one of [1] to [6] above, wherein the double-sided adhesive sheet contains particles.

[0029] [8] The method for manufacturing a semiconductor device according to [7] above, wherein the particles are thermally expandable particles.

[0030] [9] A method for manufacturing a semiconductor device as described in [8] above, wherein the double-sided adhesive sheet has an adhesive layer (X1), a substrate layer (Y) and an adhesive layer (X2) in sequence, and the adhesive layer (X1) is a heat-expandable layer containing the heat-expandable particles.

[0031]

[10] A method for manufacturing a semiconductor device as described in [8] above, wherein the double-sided adhesive sheet has an adhesive layer (X1), a substrate layer (Y) and an adhesive layer (X2) in sequence, and the substrate layer (Y) is a heat-expandable layer containing the heat-expandable particles.

[0032]

[11] The method for manufacturing a semiconductor device according to

[10] above, wherein the substrate layer (Y) is a substrate laminate in which a heat-expandable substrate layer (Y1) containing heat-expandable particles and a non-heat-expandable substrate layer (Y2) are laminated.

[0033] The double-sided pressure-sensitive adhesive sheet includes the pressure-sensitive adhesive layer (X1), the heat-expandable substrate layer (Y1), the non-heat-expandable substrate layer (Y2), and the pressure-sensitive adhesive layer (X2) in this order.

[0034]

[12] The method for manufacturing a semiconductor device as described in any one of [1] to

[11] above, wherein the object to be processed is a semiconductor wafer.

[0035]

[13] The method for manufacturing a semiconductor device as described in any one of [1] to

[12] above, wherein, before step 2, at least one step selected from the group consisting of a step of forming a groove on the surface of the object on the double-sided adhesive sheet side and a step of forming a modified region inside the object is included.

[0036] The step 2 is a step of grinding the object to be processed in a state where the support of the stack is fixed, and dividing the object to be processed into individual pieces with the groove or the modified region as a starting point.

[0037] Effects of the Invention

[0038] According to the present invention, a method for manufacturing a semiconductor device in which the thickness uniformity of the object to be processed after grinding is excellent can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a cross-sectional view showing an example of the structure of a double-sided PSA sheet.

[0040] Figure 2 This is a cross-sectional view showing an example of the structure of a double-sided PSA sheet.

[0041] Figure 3 This is a cross-sectional view for explaining an example of the process of the method for manufacturing a semiconductor device of the present invention.

[0042] Figure 4 This is a cross-sectional view for explaining an example of the process of the method for manufacturing a semiconductor device of the present invention.

[0043] Figure 5 This is a cross-sectional view for explaining an example of the process of the method for manufacturing a semiconductor device of the present invention.

[0044] Figure 6 This is a cross-sectional view for explaining an example of the process of the method for manufacturing a semiconductor device of the present invention.

[0045] Figure 7 This is a cross-sectional view for explaining an example of the process of the method for manufacturing a semiconductor device of the present invention.

[0046] Figure 8 This is a cross-sectional view for explaining an example of the process of the method for manufacturing a semiconductor device of the present invention.

[0047] Fig. 9 This is a cross-sectional view for explaining an example of the process of the method for manufacturing a semiconductor device of the present invention.

[0048] Fig.10 This is a cross-sectional view for explaining an example of the process of the method for manufacturing a semiconductor device of the present invention.

[0049] Explanation of symbols

[0050] 1. Grinder

[0051] 2 Laser irradiation device

[0052] 3 Modified area

[0053] 4 Thermosetting film

[0054] 5 Support

[0055] (A), (A1), (A2) Double-sided adhesive sheets

[0056] (X1) Adhesive layer (X1)

[0057] (X2) Adhesive layer (X2)

[0058] (Y) Base material layer (Y)

[0059] (Y1) Heat expandable base material layer (Y1)

[0060] (Y2) Non-heat-expandable base material layer (Y2)

[0061] R Stripping material

[0062] S support

[0063] T fixed table

[0064] W Semiconductor Wafer

[0065] Wα Circuit surface of semiconductor wafer W

[0066] Wβ Back side of semiconductor wafer W

[0067] CP Semiconductor Chip DETAILED DESCRIPTION

[0068] In the present specification, the "active ingredient" refers to the ingredient other than the diluent solvent among the ingredients contained in the subject composition.

[0069] In addition, in this specification, the weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) method in terms of standard polystyrene, and specifically, it is a value measured based on the method described in Examples.

[0070] In this specification, for the preferred numerical range, the lower limit and upper limit described in steps can be combined independently. For example, according to the description of "preferably 10 to 90, more preferably 30 to 60", "preferably the lower limit (10)" and "more preferably the upper limit (60)" can be combined to obtain "10 to 60".

[0071] In this specification, for example, "(meth)acrylic acid" means both "acrylic acid" and "methacrylic acid", and the same applies to other similar terms.

[0072] In this specification, "energy rays" refer to those having energy quanta in electromagnetic waves or charged particle beams, and examples thereof include ultraviolet rays, radiation, electron beams, etc. For example, an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, etc. can be used as an ultraviolet light source to irradiate ultraviolet rays. As for electron beams, electron beams generated by electron beam accelerators, etc. can be irradiated.

[0073] In the present specification, "energy ray polymerizable" means a property of being polymerized by irradiation with energy rays. Also, "energy ray curable" means a property of being cured by irradiation with energy rays.

[0074] In the present specification, whether a “layer” is a “non-heat-expandable layer” or a “heat-expandable layer” can be determined as follows.

[0075] When the layer to be judged contains heat-expandable particles, the layer is subjected to a heat treatment for 3 minutes at the expansion starting temperature (t) of the heat-expandable particles. When the volume change rate calculated by the following formula is less than 5%, the layer is judged to be a "non-heat-expandable layer", and when it is more than 5%, the layer is judged to be a "heat-expandable layer".

[0076] Volume change rate (%) = {(volume of the layer after heat treatment - volume of the layer before heat treatment) / volume of the layer before heat treatment} × 100

[0077] In addition, a layer not containing heat-expandable particles is referred to as a "non-heat-expandable layer".

[0078] In the present specification, when the "layer" is a non-thermally expandable layer, the volume change rate (%) of the non-thermally expandable layer calculated by the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, further preferably less than 0.1%, and further preferably less than 0.01%.

[0079] In addition, in this specification, when the "layer" is a non-thermally expandable layer, the non-thermally expandable layer preferably does not contain heat-expandable particles, but may contain heat-expandable particles within the scope of not violating the purpose of the present invention. When the non-thermally expandable layer contains heat-expandable particles, the less the content, the more preferred, relative to the total mass (100 mass %) of the non-thermally expandable layer, preferably less than 3 mass %, more preferably less than 1 mass %, further preferably less than 0.1 mass %, further preferably less than 0.01 mass %, further preferably less than 0.001 mass %.

[0080] In this specification, the "circuit surface" of a semiconductor wafer refers to a surface on which a circuit is formed, and the "back surface" of a semiconductor wafer refers to a surface on which no circuit is formed.

[0081] In this specification, "semiconductor device" refers to any device that can function by utilizing semiconductor characteristics. For example, a wafer having an integrated circuit, a wafer having an integrated circuit that has been thinned, a chip having an integrated circuit, a chip having an integrated circuit that has been thinned, electronic components including these chips, and electronic devices having the electronic components.

[0082] In this specification, the thickness of each layer refers to the thickness at 23° C. and is a value measured by the method described in the Examples.

[0083] The mechanism of action described in this specification is speculative and does not limit the mechanism by which the effects of the present invention are achieved.

[0084] [Method for manufacturing semiconductor device]

[0085] The method for manufacturing a semiconductor device of this embodiment includes the following steps 1 and 2 in sequence.

[0086] Step 1: a step of producing a laminate having a support, a double-sided adhesive sheet, and an object to be processed in this order,

[0087] Step 2: a step of grinding the object to be processed while the support of the stack is fixed.

[0088] The step 1 includes a support grinding process of grinding the support adhered to the double-sided pressure-sensitive adhesive sheet.

[0089] The reason why the method for manufacturing a semiconductor device of the present embodiment makes the thickness uniformity of the object to be processed after grinding excellent is not clear, but is presumed as follows.

[0090] When grinding the object, the object, double-sided adhesive sheet and support body before grinding are stacked in sequence to form a stacked body for processing, and the support body of the stacked body is fixed to a fixture such as a chuck table, and the object is ground using a grinder etc. At this time, when using the previous method, it can be considered that the uneven pressure when the adhesive sheet of the object to be processed and the object to be processed and the support body are pasted to the adhesive sheet causes the stacked body for processing to produce a deviation in thickness. And by fixing the stacked body having a thickness deviation to a fixture, it can be considered that the surface of the object to be processed before grinding produces unevenness, and the grinding amount of the convex portion becomes relatively more, thereby causing the object to be processed after grinding to produce a deviation in thickness.

[0091] On the other hand, the method for manufacturing a semiconductor device of the present embodiment includes a support body grinding process of grinding a support body attached to the opposite side of the processing object before grinding the processing object. It is estimated that the thickness of the stacked body for processing becomes uniform through the support body grinding process, and the surface of the processing object before grinding becomes flat, thereby making the thickness uniformity of the processing object after grinding excellent.

[0092] Hereinafter, first, a double-sided adhesive sheet used in the method for manufacturing a semiconductor device of the present embodiment will be described, and then each step included in the method for manufacturing a semiconductor device of the present embodiment will be described in detail.

[0093] [Double-sided adhesive sheet]

[0094] The double-sided adhesive sheet used in the semiconductor device manufacturing method of this embodiment has a support body attached to the adhesive layer on one side and an object to be processed attached to the adhesive layer on the other side. The double-sided adhesive sheet is peeled off from the object to be processed after a predetermined process is performed on the object to be processed.

[0095] The PSA layer of the double-sided PSA sheet preferably has a mechanism of action that reduces the adhesive force from the viewpoint of facilitating release from the object to be processed and the support after processing.

[0096] As the adhesive layer having a mechanism of action of reducing adhesive force, for example, there can be mentioned: an adhesive layer that reduces adhesive force by curing the adhesive by irradiating energy rays; an adhesive layer that reduces adhesive force by generating gas by irradiating energy rays; an adhesive layer that reduces adhesive force by changing the crystallinity of the adhesive by heating or cooling; an adhesive layer that reduces adhesive force by thermal expansion, etc. Among these, the adhesive layer on one side of the double-sided adhesive sheet is preferably an adhesive layer that reduces adhesive force by thermal expansion.

[0097] It should be noted that the mechanism of action of the adhesive force reduction of the adhesive layer on one side and the adhesive layer on the other side of the preferred double-sided adhesive sheet is different from each other. Thus, when the process of reducing the adhesive force of the adhesive layer on either side is carried out, it is possible to avoid unexpectedly reducing the adhesive force of the adhesive layer on the other side. From this viewpoint, the adhesive layer on one side of the double-sided adhesive sheet used in the manufacturing method of the semiconductor device of the preferred embodiment is an adhesive layer that utilizes thermal expansion to reduce the adhesive force, and the adhesive layer on the other side is an adhesive layer that reduces the adhesive force by irradiating energy rays to solidify the adhesive.

[0098] In addition, the double-sided adhesive sheet suitable for the method for manufacturing a semiconductor device of the present embodiment preferably contains particles. According to the method for manufacturing a semiconductor device of the present embodiment, the thickness deviation of the double-sided adhesive sheet is not easily expressed as the thickness deviation of the object to be processed after grinding. Therefore, in the method for manufacturing a semiconductor device of the present embodiment, a double-sided adhesive sheet containing particles that may be the cause of thickness deviation is also suitable for use.

[0099] Examples of particles that may be contained in the double-sided pressure-sensitive adhesive sheet include heat-expandable particles and inorganic particles added for the purpose of various modifications.

[0100] Hereinafter, a double-sided PSA sheet in which one PSA layer is a PSA layer whose adhesive strength is reduced by thermal expansion will be described in detail.

[0101] The double-sided adhesive sheet in which the adhesive layer on one side is an adhesive layer whose adhesive strength is reduced by thermal expansion is preferably a double-sided adhesive sheet (A) which comprises an adhesive layer (X1), a substrate layer (Y) and an adhesive layer (X2) in this order, at least one of the adhesive layer (X1) and the substrate layer (Y) being a thermally expandable layer containing thermally expandable particles, and by expanding the thermally expandable layer, projections and depressions are formed on the surface of the adhesive layer (X1).

[0102] The double-sided adhesive sheet (A) is a double-sided adhesive sheet in which the heat-expandable particles contained in the heat-expandable layer as at least one layer of the adhesive layer (X1) and the substrate layer (Y) are heated to a temperature above the expansion starting temperature (t) to expand, thereby forming a concave-convex surface of the adhesive surface of the adhesive layer (X1), thereby greatly reducing the contact area between the adherend attached to the adhesive surface of the adhesive layer (X1) and the adhesive surface. As a result, the adhesion between the adhesive surface of the adhesive layer (X1) and the adherend can be significantly reduced, and the double-sided adhesive sheet (A) can be easily separated from the adherend.

[0103] The adherend of the adhesive layer (X1) attached to the double-sided adhesive sheet (A) is preferably a support. By attaching the support to the adhesive layer (X1) having excellent releasability after heat treatment, even if the support is made of a hard material, it can be heated and peeled without causing the double-sided adhesive sheet (A) and the support to bend.

[0104] The double-sided adhesive sheet (A) only needs to have an adhesive layer (X1), a substrate layer (Y) and an adhesive layer (X2) in this order, and may have only an adhesive layer (X1), a substrate layer (Y) and an adhesive layer (X2), or may have other layers as required. However, one surface of the double-sided adhesive sheet (A) is the adhesive surface of the adhesive layer (X1), and the other surface of the double-sided adhesive sheet (A) is the adhesive surface of the adhesive layer (X2).

[0105] The double-sided pressure-sensitive adhesive sheet (A) may be any layer as long as at least one of the pressure-sensitive adhesive layer (X1) and the substrate layer (Y) is a heat-expandable layer containing heat-expandable particles.

[0106] Examples of the double-sided adhesive sheet (A) in which the substrate layer (Y) is a heat-expandable layer containing heat-expandable particles include a double-sided adhesive sheet having an adhesive layer (X1), a substrate layer (Y), and an adhesive layer (X2) in this order, wherein the substrate layer (Y) is a heat-expandable layer containing the heat-expandable particles (hereinafter also referred to as a "double-sided adhesive sheet (A1)").

[0107] In addition, as a double-sided adhesive sheet (A) in the case where the adhesive layer (X1) is a heat-expandable layer containing heat-expandable particles, there can be mentioned a double-sided adhesive sheet which has an adhesive layer (X1), a base layer (Y), and an adhesive layer (X2) in this order, and the above-mentioned adhesive layer (X1) is a heat-expandable layer containing the above-mentioned heat-expandable particles (hereinafter also referred to as "double-sided adhesive sheet (A2)").

[0108] Among these, as double-sided adhesive sheet (A), preferably, the substrate layer (Y) is a double-sided adhesive sheet of a heat-expandable layer containing heat-expandable particles. By making the substrate layer (Y) contain heat-expandable particles, the thickness of the adhesive layer is adjusted, the adhesive force, the control of the viscoelastic modulus, etc., the degree of freedom of design is improved, and the dislocation of the adherend is easily suppressed. In addition, the residue from the heat-expandable particles and a part of the adhesive layer that is greatly deformed can be suppressed from being attached to the chip, or the concavo-convex shape formed in the adhesive layer is transferred to the adherend, and the cleanliness of the adherend is easily maintained.

[0109] The double-sided adhesive sheet (A1) in which the substrate layer (Y) is a heat-expandable layer containing heat-expandable particles is preferably a substrate laminate in which a heat-expandable substrate layer (Y1) containing heat-expandable particles and a non-heat-expandable substrate layer (Y2) are laminated, and the double-sided adhesive sheet has an adhesive layer (X1), a heat-expandable substrate layer (Y1), a non-heat-expandable substrate layer (Y2) and an adhesive layer (X2) in this order.

[0110] Figure 1 In the figure, as a double-sided PSA sheet (A1), a double-sided PSA sheet having a PSA layer (X1), a heat-expandable substrate layer (Y1), a non-heat-expandable substrate layer (Y2), and a PSA layer (X2) in this order is shown.

[0111] Figure 2 In the figure, as a double-sided PSA sheet (A2), a double-sided PSA sheet having a PSA layer (X1) as a heat expandable layer, a base layer (Y), and a PSA layer (X2) in this order is shown.

[0112] The double-sided adhesive sheet (A) may or may not have another layer between the substrate layer (Y) and the adhesive layer (X1). In addition, the double-sided adhesive sheet (A) may or may not have another layer between the substrate layer (Y) and the adhesive layer (X2).

[0113] However, it should be noted that when the double-sided adhesive sheet (A1) has an adhesive layer (X1), a heat-expandable substrate layer (Y1), a non-heat-expandable substrate layer (Y2) and an adhesive layer (X2) in this order, it is preferred that the non-heat-expandable substrate layer (Y2) is directly laminated on the surface of the heat-expandable substrate layer (Y1) opposite to the adhesive layer (X1) from the viewpoint of suppressing the expansion of the surface.

[0114] In the double-sided PSA sheet (A2), a layer capable of suppressing swelling of the PSA layer (X1) is preferably directly laminated on the surface opposite to the adhesive surface, and more preferably a substrate layer (Y) is directly laminated on the surface.

[0115] <Thermal expansion particles>

[0116] From the viewpoint of suppressing thermal changes in the object to be processed during heat peeling, the expansion starting temperature (t) of the heat-expandable particles is preferably less than 125°C, more preferably 120°C or less, further preferably 115°C or less, further preferably 110°C or less, and further preferably 105°C or less.

[0117] The expansion starting temperature (t) of the heat-expandable particles is preferably 50° C. or higher, more preferably 55° C. or higher, further preferably 60° C. or higher, and further preferably 70° C. or higher.

[0118] When the expansion starting temperature (t) of the heat-expandable particles is not less than the above lower limit, unintended expansion of the heat-expandable particles due to a temperature rise during grinding of an object can be suppressed.

[0119] In addition, in this specification, the expansion starting temperature (t) of the heat-expandable particle means the value measured by the following method.

[0120] (Method for measuring expansion starting temperature (t) of heat-expandable particles)

[0121] 0.5 mg of heat-expandable particles to be measured were placed in an aluminum cup having a diameter of 6.0 mm (inner diameter of 5.65 mm) and a depth of 4.8 mm, and an aluminum cap (diameter of 5.6 mm, thickness of 0.1 mm) was placed on the cup to prepare a sample.

[0122] The height of the sample was measured using a dynamic viscoelasticity measuring device while applying a force of 0.01 N to the sample with an indenter from above the aluminum cover. Thereafter, the sample was heated from 20°C to 300°C at a heating rate of 10°C / min while applying a force of 0.01 N with the indenter, and the displacement of the indenter in the vertical direction was measured, and the temperature at which the displacement in the positive direction started was defined as the expansion starting temperature (t).

[0123] As the heat-expandable particles, preferably, are microencapsulated foaming agents composed of an outer shell formed of a thermoplastic resin and an inner component encapsulated by the outer shell and vaporized when heated to a predetermined temperature.

[0124] Examples of the thermoplastic resin constituting the shell of the microencapsulated foaming agent include polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, and copolymers obtained by polymerizing two or more monomers forming structural units contained in these thermoplastic resins.

[0125] Examples of the component enclosed by the shell of the microencapsulated foaming agent, i.e., the inner component, include low-boiling point liquids such as propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, n-heptane, n-octane, cyclopropane, cyclobutane, and petroleum ether.

[0126] Among these, from the viewpoint of suppressing thermal changes in the object to be processed during heat peeling and suppressing the unintended expansion of the heat-expandable particles caused by the temperature rise during grinding of the object to be processed, when the expansion starting temperature (t) of the heat-expandable particles is 50° C. or higher and lower than 125° C., the inner component is preferably propane, isobutane, n-pentane, and cyclopropane.

[0127] These internal components may be used alone or in combination of two or more.

[0128] The expansion starting temperature (t) of the heat-expandable particles can be adjusted by appropriately selecting the type of the contained components.

[0129] The average particle size of the heat-expandable particles before expansion at 23° C. is preferably 3 to 100 μm, more preferably 4 to 70 μm, further preferably 6 to 60 μm, and further preferably 10 to 50 μm.

[0130] It should be noted that the average particle size of the heat-expandable particles before expansion is the volume median particle size (D 50), represents the particle size distribution of the heat-expandable particles before expansion measured using a laser diffraction particle size distribution measuring apparatus (e.g., manufactured by Malvern, product name "Mastersizer 3000"), in which the cumulative volume frequency calculated from the smaller particle size of the heat-expandable particles before expansion is equivalent to 50% of the particle size.

[0131] The 90% particle size (D 90 ), preferably 10 to 150 μm, more preferably 15 to 100 μm, further preferably 20 to 90 μm, and further preferably 25 to 80 μm.

[0132] In addition, the 90% particle size (D 90 ) represents the particle size distribution of the heat-expandable particles before expansion measured using a laser diffraction particle size distribution measuring apparatus (e.g., manufactured by Malvern, product name "Mastersizer 3000"), in which the cumulative volume frequency calculated from the smaller particle size of the heat-expandable particles before expansion is equivalent to the particle size of 90%.

[0133] The maximum volume expansion ratio of the heat-expandable particles when heated to a temperature not lower than the expansion starting temperature (t) is preferably 1.5 to 200 times, more preferably 2 to 150 times, further preferably 2.5 to 120 times, and further preferably 3 to 100 times.

[0134] The content of the heat-expandable particles in the heat-expandable layer is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 7% by mass or more, and further preferably 10% by mass or more, relative to the total mass (100% by mass) of the heat-expandable layer. In addition, the content of the heat-expandable particles in the heat-expandable layer is preferably 25% by mass or less, more preferably 20% by mass or less, further preferably 16% by mass or less, and further preferably 14% by mass or less, relative to the total mass (100% by mass) of the heat-expandable layer.

[0135] When the content of heat-expandable particles is more than 1% by mass, there is a tendency that the peelability during heat peeling increases. In addition, when the content of heat-expandable particles is less than 25% by mass, there is a tendency that the generation of the concavoconvex caused by the heat-expandable particles before thermal expansion can be suppressed, and good adhesion is obtained.

[0136] <Thickness of thermal expansion layer>

[0137] The thickness of the heat expandable layer before thermal expansion is preferably 10 to 200 μm, more preferably 20 to 150 μm, and even more preferably 25 to 120 μm.

[0138] When the thickness of the heat expandable layer before thermal expansion is 10 μm or more, the formation of irregularities caused by the heat expandable particles before thermal expansion can be suppressed. In addition, when the thickness of the heat expandable layer before thermal expansion is 200 μm or less, the double-sided adhesive sheet tends to be easier to handle.

[0139] Next, double-sided PSA sheet (A1) and double-sided PSA sheet (A2) which are more specific embodiments of the double-sided PSA sheet (A) will be described.

[0140] [Double-sided adhesive sheet (A1)]

[0141] The double-sided PSA sheet (A1) comprises a PSA layer (X1), a substrate layer (Y), and a PSA layer (X2) in this order, wherein the substrate layer (Y) is a heat expandable layer containing the heat expandable particles.

[0142] <Adhesive layer (X1)>

[0143] The pressure-sensitive adhesive layer (X1) of the double-sided pressure-sensitive adhesive sheet (A1) may be a heat-expandable layer or a non-heat-expandable layer, but is preferably a non-heat-expandable layer.

[0144] The PSA layer (X1) of the double-sided PSA sheet (A1) can be formed from a PSA composition (x-1) containing a PSA resin.

[0145] Hereinafter, each component contained in the adhesive composition (x-1) will be described.

[0146] (Adhesive resin)

[0147] Examples of the adhesive resin include polymers having adhesive properties alone and a weight average molecular weight (Mw) of 10,000 or more.

[0148] From the viewpoint of improving the adhesive strength of the adhesive layer (X1), the weight average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and even more preferably 30,000 to 1,000,000.

[0149] Specific examples of adhesive resins include rubber resins such as acrylic resins, urethane resins, and polyisobutylene resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins. Among these, acrylic resins are preferred from the viewpoint of exhibiting excellent adhesive strength.

[0150] These adhesive resins may be used alone or in combination of two or more.

[0151] When the adhesive resin is a copolymer having two or more structural units, the form of the copolymer is not particularly limited, and may be any of a block copolymer, a random copolymer and a graft copolymer.

[0152] The adhesive resin preferably has a functional group. Examples of the functional group include a hydroxyl group, a carboxyl group, an amino group, and an epoxy group. Among them, a hydroxyl group is preferred.

[0153] Relative to the total amount (100 mass%) of the active ingredients of the adhesive composition (x-1), the content of the adhesive resin in the adhesive composition (x-1) is preferably 35 to 100 mass%, more preferably 50 to 100 mass%, further preferably 60 to 100 mass%, and further preferably 70 to 99.5 mass%.

[0154] (Crosslinking agent)

[0155] When the adhesive composition (x-1) contains an adhesive resin having a functional group, it preferably further contains a crosslinking agent.

[0156] The crosslinking agent reacts with the adhesive resin having a functional group, and crosslinks the adhesive resins with each other using the functional group as a crosslinking starting point.

[0157] Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, and metal chelate crosslinking agents.

[0158] These cross-linking agents may be used alone or in combination of two or more.

[0159] Among these crosslinking agents, isocyanate crosslinking agents are preferred from the viewpoints of improving cohesive force and thus adhesive force, and from the viewpoints of easy availability and the like.

[0160] As the isocyanate crosslinking agent, from the viewpoint of suppressing the decrease in the elastic modulus of the adhesive layer (X1) when heated, it is preferred to use an isocyanurate type modified product containing an isocyanurate ring, more preferably an isocyanurate type modified product of acyclic aliphatic polyisocyanate, and still more preferably an isocyanurate type modified product of hexamethylene diisocyanate.

[0161] The content of the crosslinking agent can be appropriately adjusted depending on the number of functional groups of the adhesive resin, and is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass based on 100 parts by mass of the adhesive resin having functional groups.

[0162] (Thickener)

[0163] From the viewpoint of further improving the adhesive strength, the adhesive composition (x-1) may further contain a tackifier.

[0164] In this specification, the term "tackifier" refers to a component that assists in improving the adhesive strength of the adhesive resin and has a weight average molecular weight (Mw) of less than 10,000, and is distinguished from the above-mentioned adhesive resin.

[0165] The weight average molecular weight (Mw) of the tackifier is less than 10,000, preferably 400 to 9,000, more preferably 500 to 8,000, and even more preferably 800 to 5,000.

[0166] Examples of the tackifier include rosin-based resins, terpene-based resins, styrene-based resins, C5-based petroleum resins obtained by copolymerizing C5 fractions such as pentene, isoprene, piperine, and 1,3-pentadiene generated by thermal decomposition of naphtha, C9-based petroleum resins obtained by copolymerizing C9 fractions such as indene and vinyltoluene generated by thermal decomposition of naphtha, and hydrogenated resins obtained by hydrogenating these resins.

[0167] The content of the tackifier is preferably 0.01 to 65 mass %, more preferably 0.1 to 50 mass %, further preferably 1 to 40 mass %, and further preferably 2 to 30 mass % relative to the total amount (100 mass %) of the active ingredients of the adhesive composition (x-1).

[0168] (Additives for adhesives)

[0169] The adhesive composition (x-1) may contain adhesive additives generally used for adhesives in addition to the above-mentioned additives within a range not impairing the effects of the present invention.

[0170] Examples of such adhesive additives include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators (catalysts), ultraviolet absorbers, energy-ray-curable compounds described below, and photopolymerization initiators.

[0171] In addition, these adhesive additives may be used individually or in combination of 2 or more types.

[0172] When these adhesive additives are contained, the content of each adhesive additive is independently preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass, based on 100 parts by mass of the adhesive resin.

[0173] (Thickness of Adhesive Layer (X1))

[0174] The thickness of the adhesive layer (X1) possessed by the double-sided adhesive sheet (A1) is preferably 3 to 10 μm, more preferably 3 to 8 μm, and even more preferably 3 to 7 μm, from the viewpoint of exhibiting good adhesive strength and forming good irregularities on the adhesive surface of the adhesive layer (X1) when the heat-expandable particles are expanded by heating.

[0175] By adjusting the thickness of the pressure-sensitive adhesive layer (X1) to the above range, the pressure-sensitive adhesive layer (X1) can be easily formed, and the unevenness can be easily formed favorably on the adhesive surface of the pressure-sensitive adhesive layer (X1).

[0176] <Base layer (Y)>

[0177] The substrate layer (Y) is preferably a non-adhesive substrate.

[0178] The probe tack value of the surface of the substrate layer (Y) is usually less than 50 mN / 5 mmφ, preferably less than 30 mN / 5 mmφ, more preferably less than 10 mN / 5 mmφ, and further preferably less than 5 mN / 5 mmφ.

[0179] In addition, in this specification, the probe viscosity value of the substrate surface means the value measured by the following method.

[0180] <Probe viscosity value>

[0181] The substrate to be measured can be cut into a square with a side length of 10 mm and then left to stand for 24 hours in an environment of 23°C and 50% RH (relative humidity) as a test sample. In an environment of 23°C and 50% RH (relative humidity), a viscosity tester (manufactured by Japan Tokushoku Instruments Co., Ltd., product name "NTS-4800") is used to measure the probe viscosity value on the surface of the test sample based on JIS Z0237:1991. Specifically, the contact load is 0.98 N / cm 2 A stainless steel probe with a diameter of 5 mm is brought into contact with the surface of the test sample for 1 second, and then the force required to separate the probe from the test sample surface at a speed of 10 mm / sec is measured. The obtained value can be taken as the probe viscosity value of the test sample.

[0182] The substrate layer (Y) is preferably a substrate laminate in which a heat-expandable substrate layer (Y1) containing heat-expandable particles and a non-heat-expandable substrate layer (Y2) are laminated.

[0183] By providing a non-heat-expandable substrate layer (Y2) as a non-heat-expandable layer on the surface of the heat-expandable substrate layer (Y1) opposite to the adhesive layer (X1), it is easy to transfer the stress generated by the expansion of the heat-expandable particles of the heat-expandable substrate layer (Y1) to the adhesive layer (X1) side, and it is easy to form good irregularities on the surface of the adhesive layer (X1).

[0184] Next, the heat-expandable base layer (Y1) and the non-heat-expandable base layer (Y2) constituting the base laminate will be described.

[0185] <Thermal expandable base material layer (Y1)>

[0186] The heat-expandable substrate layer (Y1) is a heat-expandable layer containing heat-expandable particles in a resin material, and is provided between the adhesive layer (X1) and the non-heat-expandable substrate layer (Y2).

[0187] From the viewpoint of increasing interlayer adhesion between the heat expandable base layer (Y1) and other laminated layers, the surface of the heat expandable base layer (Y1) may be subjected to surface treatment such as oxidation or embossing, adhesion-facilitating treatment, or primer treatment.

[0188] Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet method), hot air treatment, ozone, and ultraviolet irradiation treatment. Examples of the roughening method include sandblasting and solvent treatment.

[0189] The heat-expandable base layer (Y1) is preferably formed of a resin composition (y-1) containing a resin and heat-expandable particles.

[0190] Hereinafter, preferred embodiments of the resin composition (y-1) will be described. It should be noted that preferred embodiments of the heat-expandable particles are as described above.

[0191] (resin)

[0192] The resin contained in the resin composition (y-1) may be a non-adhesive resin or an adhesive resin.

[0193] That is, even if the resin contained in the resin composition (y-1) is an adhesive resin, as long as the adhesive resin undergoes a polymerization reaction with a polymerizable compound during the process of forming the heat-expandable substrate layer (Y1) from the resin composition (y-1), the resulting resin becomes a non-adhesive resin, and the heat-expandable substrate layer (Y1) containing the resin becomes non-adhesive.

[0194] The weight average molecular weight (Mw) of the resin contained in the resin composition (y-1) is preferably 1,000 to 1,000,000, more preferably 1,000 to 700,000, and even more preferably 1,000 to 500,000.

[0195] When the resin is a copolymer having two or more structural units, the form of the copolymer is not particularly limited, and may be any of a block copolymer, a random copolymer, and a graft copolymer.

[0196] The content of the resin is preferably 50 to 99 mass %, more preferably 60 to 95 mass %, further preferably 65 to 93 mass %, and further preferably 70 to 90 mass % relative to the total amount (100 mass %) of the active ingredients of the resin composition (y-1).

[0197] The resin contained in the resin composition (y-1) preferably contains one or more selected from acrylic urethane resins and olefin resins from the viewpoint of easily forming unevenness on the adhesive surface of the adhesive layer (X1) and from the viewpoint of good sheet shape retention after thermal expansion. That is, the heat-expandable substrate layer (Y1) preferably contains one or more selected from acrylic urethane resins and olefin resins.

[0198] Moreover, as said acrylic urethane resin, the following resin (U1) is preferable.

[0199] An acrylic urethane resin (U1) formed by polymerizing a urethane prepolymer (UP) and a (meth)acrylate-containing vinyl compound.

[0200] In addition, in this specification, a prepolymer means a compound which is formed by polymerizing a monomer and can constitute a polymer by further polymerization.

[0201] (Additives for base materials)

[0202] The resin composition (y-1) may contain a substrate additive as necessary within a range not impairing the effects of the present invention.

[0203] Examples of the additive for the substrate include ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, and colorants.

[0204] In addition, these additives for substrates may be used alone or in combination of two or more.

[0205] When these additives for base materials are contained, the content of each additive for base materials is independently preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass, based on 100 parts by mass of the resin.

[0206] (Solvent-free resin composition (y-1a))

[0207] As one embodiment of the resin composition (y-1), for example, a solvent-free resin composition (y-1a) is included which is prepared by mixing an oligomer having an ethylenically unsaturated group and a weight average molecular weight (Mw) of 50,000 or less, an energy beam polymerizable monomer, and the above-mentioned thermally expandable particles without mixing with a solvent.

[0208] Although no solvent is added to the solvent-free resin composition (y-1a), the energy-ray polymerizable monomer is a component that contributes to improving the plasticity of the oligomer.

[0209] By irradiating the solvent-free resin composition (y-1a) with energy rays, oligomers having an ethylenically unsaturated group, energy ray-polymerizable monomers, and the like are polymerized to form a heat-expandable base layer (Y1).

[0210] The weight average molecular weight (Mw) of the oligomer contained in the solvent-free resin composition (y-1a) is 50,000 or less, preferably 1,000 to 50,000, more preferably 2,000 to 40,000, further preferably 3,000 to 35,000, and further preferably 4,000 to 30,000.

[0211] The oligomer may be any oligomer having an ethylenically unsaturated group and having a weight average molecular weight of 50,000 or less among the resins contained in the resin composition (y-1), and is preferably the urethane prepolymer (UP), and more preferably a linear urethane prepolymer having ethylenically unsaturated groups at both ends.

[0212] It should be noted that a modified olefin resin having an ethylenically unsaturated group may be used as the oligomer.

[0213] The total content of the above-mentioned oligomers and energy-ray polymerizable monomers in the solvent-free resin composition (y-1a) is preferably 50 to 99 mass %, more preferably 60 to 95 mass %, further preferably 65 to 90 mass %, and further preferably 70 to 85 mass %, relative to the total amount (100 mass %) of the solvent-free resin composition (y-1a).

[0214] Examples of energy-ray polymerizable monomers include alicyclic polymerizable compounds such as isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, adamantane (meth)acrylate, and tricyclodecane acrylate; aromatic polymerizable compounds such as phenylhydroxypropyl acrylate, benzyl acrylate, and phenol ethylene oxide-modified acrylate; and heterocyclic polymerizable compounds such as tetrahydrofurfuryl (meth)acrylate, morpholine acrylate, N-vinyl pyrrolidone, and N-vinyl caprolactam. Among these, isobornyl (meth)acrylate and phenylhydroxypropyl acrylate are preferred.

[0215] These energy ray polymerizable monomers may be used alone or in combination of two or more.

[0216] The content ratio of the oligomer to the energy-ray polymerizable monomer in the solvent-free resin composition (y-1a) [oligomer / energy-ray polymerizable monomer] is preferably 20 / 80 to 90 / 10, more preferably 30 / 70 to 85 / 15, and further preferably 35 / 65 to 80 / 20 in terms of mass ratio.

[0217] It is preferred that a photopolymerization initiator is further blended into the solvent-free resin composition (y-1a).

[0218] By containing a photopolymerization initiator, even when irradiated with energy rays having relatively low energy, the curing reaction can be sufficiently advanced.

[0219] Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, diacetyl, β-chloroanthraquinone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0220] These photopolymerization initiators may be used alone or in combination of two or more.

[0221] The amount of the photopolymerization initiator to be added is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass, and even more preferably 0.02 to 3 parts by mass, based on the total amount (100 parts by mass) of the oligomer and the energy ray polymerizable monomer.

[0222] (Thickness of the Heat-Expandable Base Material Layer (Y1))

[0223] The thickness of the heat-expandable base layer (Y1) before thermal expansion is preferably 10 to 200 μm, more preferably 20 to 150 μm, and even more preferably 25 to 120 μm.

[0224] When the thickness of the heat-expandable substrate layer (Y1) before thermal expansion is 10 μm or more, the formation of concavoconvexity caused by the heat-expandable particles before thermal expansion can be suppressed, and the adhesive force of the adhesive layer (X1) can be improved. When the thickness of the heat-expandable substrate layer (Y1) before thermal expansion is 200 μm or less, there is a tendency that the handling of the double-sided adhesive sheet becomes easy.

[0225] <Non-thermal expansion base material layer (Y2)>

[0226] The non-heat-expandable base layer (Y2) of the double-sided PSA sheet is provided on the surface of the heat-expandable base layer (Y1) opposite to the surface on which the PSA layer (X1) is laminated.

[0227] The non-heat-expandable substrate layer (Y2) is preferably a non-adhesive substrate. The probe viscosity value of the surface of the non-heat-expandable substrate layer (Y2) is usually less than 50 mN / 5 mmφ, preferably less than 30 mN / 5 mmφ, more preferably less than 10 mN / 5 mmφ, and further preferably less than 5 mN / 5 mmφ.

[0228] Examples of the material for forming the non-thermally expandable base material layer (Y2) include resins, metals, and paper materials.

[0229] Examples of the resin include polyolefin resins such as polyethylene and polypropylene; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; urethane resins such as polyurethane and acrylic modified polyurethane; polymethylpentene; polysulfone; polyetheretherketone; polyethersulfone; polyphenylene sulfide; polyimide resins such as polyetherimide and polyimide; polyamide resins; acrylic resins; fluorine resins, etc.

[0230] Examples of the metal include aluminum, tin, chromium, and titanium.

[0231] Examples of the paper material include thin paper, medium-quality paper, premium paper, impregnated paper, coated paper, art paper, sulphate paper, and glass paper.

[0232] Among these, polyester resins such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate are preferred.

[0233] These forming materials may be composed of one kind or two or more kinds may be used in combination.

[0234] Examples of the non-heat-expandable base material layer (Y2) formed by combining two or more materials include a material obtained by laminating a paper material with a thermoplastic resin such as polyethylene, and a material obtained by forming a metal film on the surface of a resin film or sheet containing a resin.

[0235] Examples of the method for forming the metal layer include a method of depositing the metal by PVD such as vacuum deposition, sputtering, or ion plating, and a method of attaching a metal foil made of the metal using a common adhesive.

[0236] It should be noted that, from the viewpoint of increasing the interlayer adhesion between the non-heat-expandable substrate layer (Y2) and other laminated layers, when the non-heat-expandable substrate layer (Y2) contains a resin, the surface of the non-heat-expandable substrate layer (Y2) can also be subjected to surface treatment based on an oxidation method, a convexo-relief method, etc., an easy-adhesion treatment, or a primer treatment in the same manner as the above-mentioned heat-expandable substrate layer (Y1).

[0237] When the non-heat-expandable substrate layer (Y2) contains a resin, the above-mentioned additive for substrates which may be contained in the resin composition (y-1) may be contained together with the resin.

[0238] (Storage modulus E'(23) of non-heat-expandable substrate layer (Y2) at 23°C)

[0239] The storage modulus E'(23) of the non-heat-expandable substrate layer (Y2) at 23°C is preferably 5.0×10 7 ~5.0×10 9 Pa, more preferably 5.0×10 8 ~4.5×10 9 Pa, more preferably 1.0×10 9 ~4.0×10 9 Pa.

[0240] The storage modulus E'(23) of the non-heat-expandable substrate layer (Y2) is 5.0×10 7 Pa or more, the deformation resistance of the double-sided adhesive sheet can be easily improved. On the other hand, the storage modulus E'(23) of the non-heat-expandable substrate layer (Y2) is 5.0×10 9 When the viscosity is not more than Pa, the handleability of the double-sided pressure-sensitive adhesive sheet can be easily improved.

[0241] In addition, in this specification, the storage modulus E'(23) of the non-heat-expandable base material layer (Y2) represents a value measured by the method described in the Examples.

[0242] (Thickness of non-heat-expandable base material layer (Y2))

[0243] The thickness of the non-heat-expandable substrate layer (Y2) is preferably 5 to 500 μm, more preferably 15 to 300 μm, and further preferably 20 to 200 μm. When the thickness of the non-heat-expandable substrate layer (Y2) is 5 μm or more, it is easy to improve the deformation resistance of the double-sided adhesive sheet. On the other hand, when the thickness of the non-heat-expandable substrate layer (Y2) is 500 μm or less, it is easy to improve the operability of the double-sided adhesive sheet.

[0244] <Adhesive layer (X2)>

[0245] The adhesive layer (X2) is a layer provided on the surface of the non-heat-expandable base layer (Y2) opposite to the stacking surface of the heat-expandable base layer (Y1).

[0246] The pressure-sensitive adhesive layer (X2) is preferably an energy-ray-curable pressure-sensitive adhesive layer that is cured by irradiation with energy rays and whose adhesive strength decreases, and more preferably a pressure-sensitive adhesive layer that is cured by irradiation with ultraviolet rays and whose adhesive strength decreases.

[0247] The adhesive layer (X2) is preferably a non-thermally expandable layer.

[0248] The adhesive layer (X2) is preferably formed from an adhesive composition (x-2) containing an adhesive resin. Hereinafter, each component contained in the adhesive composition (x-2) will be described.

[0249] The adhesive composition (x-2) is a composition containing an adhesive resin, and may contain a crosslinking agent, a tackifier, a polymerizable compound, a polymerization initiator, and adhesive additives that can be used in general adhesives in addition to the above components, as required.

[0250] (Adhesive resin)

[0251] The adhesive resin may be any polymer as long as the resin alone has adhesiveness and has a weight average molecular weight (Mw) of 10,000 or more.

[0252] From the viewpoint of further improving the adhesive force of the adhesive layer (X2), the weight average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and even more preferably 30,000 to 1,000,000.

[0253] Examples of the adhesive resin include the same adhesive resins as those contained in the adhesive composition (x-1). Among these, acrylic resins are preferably contained from the viewpoint of exhibiting excellent adhesive strength.

[0254] These adhesive resins may be used alone or in combination of two or more.

[0255] When the adhesive resin is a copolymer having two or more structural units, the copolymer may be in the form of a block copolymer, a random copolymer, or a graft copolymer.

[0256] From the viewpoint of making the obtained adhesive layer (X2) a adhesive layer that is cured by irradiation with energy rays and has reduced adhesive strength, the adhesive resin contained in the adhesive composition (x-2) is preferably an adhesive resin having an energy ray polymerizable functional group in its side chain.

[0257] Examples of the energy beam polymerizable functional group include those having a carbon-carbon double bond, such as a (meth)acryloyl group, a vinyl group, and an allyl group.

[0258] Relative to the total amount (100 mass%) of the active ingredients of the adhesive composition (x-2), the content of the adhesive resin in the adhesive composition (x-2) is preferably 35 to 100 mass%, more preferably 50 to 100 mass%, further preferably 60 to 98 mass%, and further preferably 70 to 95 mass%.

[0259] (Energy ray curable compound)

[0260] The adhesive composition (x-2) may contain, in addition to the adhesive resin, a monomer or oligomer that can be polymerized and cured by irradiation with energy rays as an energy-ray-curable compound.

[0261] Examples of such energy-ray-curable compounds include poly(meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol (meth)acrylate; and oligomers such as polyfunctional urethane (meth)acrylate, polyfunctional polyester (meth)acrylate, polyfunctional polyether (meth)acrylate, and polyfunctional epoxy (meth)acrylate.

[0262] Among these, polyfunctional urethane (meth)acrylate oligomers are preferred because they have a relatively high molecular weight and are less likely to cause a decrease in the elastic modulus of the pressure-sensitive adhesive layer (X2).

[0263] The molecular weight of the energy beam curable compound (in the case of an oligomer, a weight average molecular weight (Mw)) is preferably 100 to 12,000, more preferably 200 to 10,000, further preferably 400 to 8,000, and further preferably 600 to 6,000.

[0264] (Photopolymerization Initiator)

[0265] The pressure-sensitive adhesive composition (x-2) preferably further contains a photopolymerization initiator.

[0266] By containing a photopolymerization initiator, the polymerization of the energy-ray polymerizable component can be more efficiently carried out.

[0267] Examples of the photopolymerization initiator include the same ones as exemplified in the description of the solvent-free resin composition (y-1a). Among these, 1-hydroxycyclohexyl phenyl ketone is preferred.

[0268] The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and even more preferably 0.05 to 3 parts by mass, based on 100 parts by mass of the total amount of the adhesive resin having an energy ray polymerizable functional group.

[0269] (Crosslinking agent)

[0270] When the adhesive composition (x-2) contains an adhesive resin having a functional group, the adhesive composition (x-2) preferably further contains a crosslinking agent.

[0271] The crosslinking agent is a component that reacts with the adhesive resin having a functional group to crosslink the adhesive resins with the functional group serving as a crosslinking starting point.

[0272] As the cross-linking agent that can be contained in the adhesive composition (x-2), those that are the same as or equivalent to the cross-linking agent that can be contained in the adhesive composition (x-1) can be listed. From the viewpoint of improving cohesive force and thus improving adhesive strength, and from the viewpoint of easy availability, isocyanate cross-linking agents are preferred.

[0273] The content of the crosslinking agent can be appropriately adjusted depending on the number of functional groups of the adhesive resin, and is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass based on 100 parts by mass of the adhesive resin having functional groups.

[0274] (Thickener)

[0275] From the viewpoint of further improving the adhesive strength, the adhesive composition (x-2) may further contain a tackifier.

[0276] As the tackifier that may be contained in the pressure-sensitive adhesive composition (x-2), those equivalent to the tackifier that may be contained in the pressure-sensitive adhesive composition (x-1) may be used.

[0277] (Additives for adhesives)

[0278] Examples of the adhesive additive include the same adhesive additives as those which may be contained in the adhesive composition (x-1).

[0279] The adhesive composition (x-2) can be produced by mixing an adhesive resin and, if necessary, a crosslinking agent, a tackifier, an adhesive additive, and the like.

[0280] (Thickness of Adhesive Layer (X2))

[0281] The thickness of the pressure-sensitive adhesive layer (X2) is preferably 5 to 150 μm, more preferably 8 to 100 μm, further preferably 12 to 80 μm, and further preferably 15 to 65 μm.

[0282] When the thickness of the adhesive layer (X2) is 5 μm or more, sufficient adhesive force is easily obtained, and there is a tendency to suppress unintended peeling and displacement of the adherend. On the other hand, when the thickness of the adhesive layer (X2) is 150 μm or less, there is a tendency to facilitate the handling of the double-sided adhesive sheet.

[0283] <Method for producing double-sided adhesive sheet (A1)>

[0284] The method for producing the double-sided adhesive sheet (A1) is not particularly limited. For example, a double-sided adhesive sheet (A1) having an adhesive layer (X1), a heat-expandable substrate layer (Y1), a non-heat-expandable substrate layer (Y2) and an adhesive layer (X2) in this order can be produced by a method having the following steps (1a) to (5a).

[0285] Step (1a): A step of applying the adhesive composition (x-1) onto the release-treated surface of the release material to form the adhesive layer (X1).

[0286] Step (2a): a step of applying the resin composition (y-1) on one side of the non-heat-expandable substrate layer (Y2) to form a substrate laminate in which the non-heat-expandable substrate layer (Y2) and the heat-expandable substrate layer (Y1) are laminated.

[0287] Step (3a): A step of laminating the adhesive surface of the adhesive layer (X1) formed in step (1a) to the surface of the substrate laminate formed in step (2a) on the thermally expandable substrate layer (Y1) side to obtain a single-sided adhesive sheet.

[0288] Step (4a): A step of applying the adhesive composition (x-2) onto the release-treated surface of the release material to form the adhesive layer (X2).

[0289] Step (5a): a step of laminating the adhesive surface of the adhesive layer (X2) formed in step (4a) to the surface of the non-thermally expandable base layer (Y2) of the single-sided adhesive sheet formed in step (3a).

[0290] In the method for producing a double-sided adhesive sheet, the resin composition (y-1), the adhesive composition (x-1), and the adhesive composition (x-2) may be further mixed with a diluent solvent to be in the form of a solution.

[0291] Examples of the coating method include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

[0292] In addition, from the viewpoint of suppressing the expansion of the heat-expandable particles, the step of drying the coating film formed by the resin composition (y-1), the adhesive composition (x-1) and the adhesive composition (x-2) is preferably carried out at a drying temperature lower than the expansion starting temperature (t) of the heat-expandable particles.

[0293] [Double-sided adhesive sheet (A2)]

[0294] The double-sided adhesive sheet (A2) is a double-sided adhesive layer comprising an adhesive layer (X1), a substrate layer (Y), and an adhesive layer (X2) in this order, wherein the adhesive layer (X1) is a heat-expandable layer containing the above-mentioned heat-expandable particles.

[0295] The description of the substrate layer (Y) included in the double-sided PSA sheet (A2) is the same as the description of the non-heat-expandable substrate layer (Y2) in the double-sided PSA sheet (A1), and the preferred embodiments are also the same.

[0296] The description of the PSA layer (X2) included in the double-sided PSA sheet (A2) is the same as the description of the PSA layer (X2) in the double-sided PSA sheet (A1), and the preferred embodiments are also the same.

[0297] The pressure-sensitive adhesive layer (X1) of the double-sided pressure-sensitive adhesive sheet (A2) is a heat-expandable layer containing heat-expandable particles, and preferably contains a pressure-sensitive adhesive resin and heat-expandable particles.

[0298] Examples of the adhesive resin include the same ones as those listed as the adhesive resin that the adhesive composition (x-1) may contain in the description of the double-sided adhesive sheet (A1). Among these, acrylic resins are preferably contained from the viewpoint of exhibiting excellent adhesive strength.

[0299] The thickness of the pressure-sensitive adhesive layer (X1) of the double-sided pressure-sensitive adhesive sheet (A2) before thermal expansion is preferably 10 to 200 μm, more preferably 20 to 150 μm, and even more preferably 25 to 120 μm.

[0300] When the thickness of the adhesive layer (X1) before thermal expansion is 10 μm or more, sufficient adhesive strength is easily obtained, and there is a tendency to suppress unintended peeling and displacement of the adherend. On the other hand, when the thickness of the adhesive layer (X1) before thermal expansion is 200 μm or less, there is a tendency to improve the peelability during thermal peeling.

[0301] <Thickness of the entire double-sided adhesive sheet (A)>

[0302] The overall thickness of the double-sided PSA sheet (A) before thermal expansion is preferably 90 to 300 μm, more preferably 100 to 250 μm, and even more preferably 130 to 200 μm.

[0303] When the overall thickness of the double-sided PSA sheet (A) is 90 μm or more, the mechanical strength of the double-sided PSA sheet becomes good and the handling becomes easy. When the overall thickness of the double-sided PSA sheet (A) is 300 μm or less, the handling of the double-sided PSA sheet tends to become easy.

[0304] [Steps of the method for manufacturing a semiconductor device]

[0305] Next, each step included in the method for manufacturing a semiconductor device according to the present embodiment will be described in sequence with reference to the drawings.

[0306] It should be noted that in the following drawings, a method of using a double-sided adhesive sheet (A) as a double-sided adhesive sheet, pasting a semiconductor wafer as a processing object on the adhesive layer (X2) of the double-sided adhesive sheet (A), and pasting a support body on the adhesive layer (X1) of the double-sided adhesive sheet (A) is used as an example for explanation, but the manufacturing method of the semiconductor device of this embodiment is not limited to this method.

[0307] <Process 1>

[0308] Step 1 is a step of producing a laminate having a support, a double-sided PSA sheet, and an object in this order, and is a step of grinding the support bonded to the double-sided PSA sheet.

[0309] In step 1, a support is attached to the pressure-sensitive adhesive layer on one side of a double-sided pressure-sensitive adhesive sheet, and a processing object is attached to the pressure-sensitive adhesive layer on the other side of the double-sided pressure-sensitive adhesive sheet.

[0310] Examples of the object to be processed include semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, LED elements, sapphire substrates, displays, and panel substrates. Among these, semiconductor wafers are preferred.

[0311] The order of pasting the support and the object to be processed is not particularly limited, and the pasting of the support may be prior to the pasting of the object to be processed, or the pasting of the object to be processed may be prior to the pasting of the support. In addition, the support and the object to be processed may also be pasted on the double-sided adhesive sheet simultaneously.

[0312] (Support)

[0313] Examples of the material of the support include metal materials such as SUS; non-metallic inorganic materials such as glass wafers and silicon wafers; resin materials such as epoxy resins, ABS resins, acrylic resins, engineering plastics, special engineering plastics, polyimide resins, and polyamide-imide resins; and composite materials such as glass epoxy resins.

[0314] Examples of the engineering plastics include nylon, polycarbonate (PC), and polyethylene terephthalate (PET).

[0315] Examples of the special engineering plastics include polyphenylene sulfide (PPS), polyethersulfone (PES), and polyetheretherketone (PEEK).

[0316] Among these, the support is preferably one or more selected from silicon wafers and glass wafers from the viewpoint of being hard and being able to effectively suppress vibration, displacement, breakage, etc. during grinding and conveying of the ground object.

[0317] The shape of the support is not particularly limited, but is preferably a plate shape.

[0318] The thickness of the support after the support grinding treatment is preferably 200 to 1,500 μm, more preferably 250 to 1,200 μm, and even more preferably 300 to 1,000 μm.

[0319] When the thickness of the support body after the support body grinding process is 200 μm or more, it is possible to effectively suppress vibration, displacement, breakage, etc. during grinding and conveying of the object to be processed after grinding. On the other hand, when the thickness of the support body after the support body grinding process is 1,500 μm or less, the weight of the support body does not become too heavy, and the handling property when conveying the object to be processed after grinding is excellent.

[0320] The support may have a laminated structure comprising a support layer and a peelable sheet laminated on one side of the support layer. When using a support having such a laminated structure, the support is attached to the double-sided adhesive sheet in such a way that the peelable sheet becomes the outermost surface, and the support grinding treatment is preferably a treatment for grinding the peelable sheet.

[0321] In the support grinding process, by grinding the releasable sheet of the support having a laminated structure, the support layer after the releasable sheet is peeled off and removed can be reused without grinding the support layer.

[0322] As the peelable sheet, for example, a single-sided adhesive sheet having a substrate layer and an adhesive layer can be used. When a single-sided adhesive sheet is used as the peelable sheet, the adhesive layer of the single-sided adhesive sheet is attached to a support layer as a support, and the substrate layer of the single-sided adhesive sheet is ground.

[0323] As the single-sided adhesive sheet, known ones may be used, or a single-sided adhesive sheet produced by appropriately using the materials listed as the materials of the double-sided adhesive sheet used in the method for manufacturing a semiconductor device of the present embodiment may be used.

[0324] The support layer of the peelable adhesive sheet is preferably at least one selected from a silicon wafer and a glass wafer from the same viewpoint as the suitable material of the support described above.

[0325] From the same viewpoint as the suitable thickness of the support after the support grinding treatment described above, the thickness of the support is preferably 200 to 1,500 μm, more preferably 250 to 1,200 μm, and even more preferably 300 to 1,000 μm.

[0326] (Support grinding process)

[0327] The support grinding treatment is a treatment for grinding the support affixed to the double-sided PSA sheet.

[0328] When the support is attached prior to the attachment of the object to be processed, the support grinding process may be performed before or after the attachment of the object to be processed.

[0329] When the support body grinding process is performed before pasting the processing object, the support body grinding process is preferably a process in which a release material is pasted on the surface of the double-sided adhesive sheet opposite to the surface on which the support body is pasted, and the support body is ground while the release material is fixed. A laminate can be produced by peeling off and removing the release material after the support body grinding process, and pasting the processing object on the exposed adhesive layer.

[0330] On the other hand, when the support grinding process is performed after the object is attached, the support grinding process is preferably performed by grinding the support attached to the other side of the double-sided PSA sheet while the object attached to one side of the double-sided PSA sheet is fixed.

[0331] As the release material, a release sheet subjected to double-sided release treatment, a release sheet subjected to single-sided release treatment, or the like can be used. Examples of the release material include a release material obtained by coating a release agent on a substrate for the release material.

[0332] Examples of the substrate for the release material include plastic films, paper, etc. Examples of the plastic film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; olefin resin films such as polypropylene resin and polyethylene resin; and examples of the paper include high-quality paper, glassine paper, and kraft paper.

[0333] Examples of the release agent include rubber elastomers such as silicone resins, olefin resins, isoprene resins, butadiene resins, long-chain alkane resins, alkyd resins, fluorine resins, etc. The release agent may be used alone or in combination of two or more.

[0334] The thickness of the release material is preferably 10 to 200 μm, more preferably 20 to 150 μm, and even more preferably 35 to 80 μm.

[0335] The grinding amount of the support body in the support body grinding process is not particularly limited, as long as it is adjusted to a range that can achieve a good thickness accuracy when grinding the object. For example, the grinding thickness can be 10 to 600 μm, 20 to 100 μm, or 30 to 70 μm.

[0336] Figure 3 A cross-sectional view illustrating a support body grinding process is shown, wherein a semiconductor chip W adhered to an adhesive layer (X2) possessed by a double-sided adhesive sheet (A) is fixed on a fixed table T, and a support body S adhered to an adhesive layer (X1) is ground using a grinder 1.

[0337] Figure 4 A cross-sectional view is shown to illustrate a support body grinding process, in which a release material R adhered to an adhesive layer (X2) possessed by a double-sided adhesive sheet (A) is fixed on a fixed table T, and a support body S adhered to an adhesive layer (X1) is ground using a grinder 1.

[0338] The semiconductor wafer W is attached so that the circuit surface Wα faces the adhesive layer (X2) side.

[0339] The semiconductor wafer W may be a silicon wafer, or a wafer of gallium arsenide, silicon carbide, sapphire, lithium tantalate, lithium niobate, gallium nitride, indium phosphide, or the like, or a glass wafer.

[0340] The thickness of the semiconductor wafer W before grinding is usually 500 to 1,000 μm.

[0341] The circuits included in the semiconductor wafer W can be formed by conventional methods such as etching and lift-off.

[0342] <Process 2>

[0343] Step 2 is a step of grinding the object to be processed in a state where the support of the laminated body produced by the support grinding treatment in step 1 is fixed.

[0344] The grinding performed on the object to be processed in step 2 may include, for example, grinding using a grinder or the like, grinding and singulation based on a blade first cutting method, a stealth first cutting method, etc. Among these, grinding and singulation based on a blade first cutting method, and grinding and singulation based on a stealth first cutting method are preferred.

[0345] The blade-first dicing method is also called the DBG method (Dicing Before Gring). The blade-first dicing method is a method in which a groove having a depth shallower than the thickness of the semiconductor wafer is formed in advance along the pre-divided line, and then the semiconductor wafer is back-ground to be thinned until the ground surface at least reaches the groove, and the wafer is singulated at the same time. The groove reached by the ground surface becomes a cut that passes through the semiconductor wafer, and the semiconductor wafer is divided by the cut and singulated into semiconductor chips. The pre-formed groove is usually provided on the surface (circuit surface) of the semiconductor wafer, and can be formed, for example, by cutting using a conventionally known wafer cutting device equipped with a dicing blade.

[0346] Stealth Dicing Before Grinding is also called SDBG (Stealth Dicing Before Grinding). Stealth Dicing Before Grinding is a method of forming a modified region inside a semiconductor wafer by laser irradiation, thinning the semiconductor wafer by grinding, and singulating the semiconductor wafer into semiconductor chips with the modified region as the cutting starting point. Specifically, while the semiconductor wafer with the modified region is thinned by back grinding, the pressure applied to the semiconductor wafer at this time is used to extend the crack from the modified region as the starting point toward the bonding surface of the semiconductor wafer with the adhesive layer, and singulate the semiconductor wafer into semiconductor chips.

[0347] It should be noted that the grinding thickness after forming the modified region may be a thickness that reaches the modified region, but even if it does not strictly reach the modified region, it may be ground to a position close to the modified region and cut using the processing pressure of a grinding wheel or the like.

[0348] When the blade pre-cutting method is used, it is preferred that grooves are formed in advance on the surface of the object to be bonded to the double-sided pressure-sensitive adhesive sheet.

[0349] On the other hand, when the stealth pre-cut method is used, the object to be processed may be irradiated with laser to form the modified region in advance before being attached to the double-sided adhesive sheet, or the object to be processed may be irradiated with laser to form the modified region after being attached to the double-sided adhesive sheet.

[0350] That is, from the viewpoint of performing the blade-first cutting method and the stealth-first cutting method, the method for manufacturing a semiconductor device of the present embodiment preferably has at least one step selected from the step of forming a groove on the surface of the double-sided adhesive sheet side of the above-mentioned processing object and the step of forming a modified region inside the above-mentioned processing object before step 2, and the above-mentioned step 2 is a step of grinding the above-mentioned processing object while the support body of the above-mentioned stack is fixed to singulate the above-mentioned processing object with the above-mentioned groove or the above-mentioned modified region as the starting point.

[0351] Figure 5 A cross-sectional view is shown for explaining a step of forming a plurality of reformed regions 3 using a laser irradiation device 2 on a semiconductor wafer W bonded to the pressure-sensitive adhesive layer ( X2 ) of a double-sided pressure-sensitive adhesive sheet (A).

[0352] Laser light is irradiated from the back surface Wβ side of the semiconductor wafer W, so that a plurality of reformed regions 3 are formed inside the semiconductor wafer W at substantially equal intervals.

[0353] Figure 6 (a) and (b) are cross-sectional views for explaining a process of thinning the semiconductor wafer W and singulating it into a plurality of semiconductor chips CP.

[0354] like Figure 6 As shown in (a), the back surface Wβ of the semiconductor wafer W after the modified region 3 is formed is ground by a grinder 1 while the support S after the support grinding process is fixed to the fixed table T. At this time, the pressure applied to the semiconductor wafer W causes the cutting to occur starting from the modified region 3. Figure 6 As shown in (b), a plurality of semiconductor chips CP are obtained after the semiconductor wafer W is thinned and singulated.

[0355] The thickness of the ground semiconductor chip CP is preferably 5 to 100 μm, more preferably 10 to 45 μm. When the grinding and singulation are performed by stealth dicing, the thickness of the ground semiconductor chip CP can be easily reduced to 50 μm or less, preferably 10 to 45 μm.

[0356] The size of the semiconductor chip CP after grinding in a plan view is preferably less than 600 mm. 2 , more preferably less than 400mm 2 , further preferably less than 300mm 2 In addition, the plan view refers to observation in the thickness direction.

[0357] The shape of the semiconductor chip CP after singulation in a plan view may be a square, or may be an elongated shape such as a rectangle.

[0358] <Process 3>

[0359] The method for manufacturing a semiconductor device according to the present embodiment may further include the following step 3.

[0360] Step 3: A step of attaching a thermosetting film to the surface of the object ground in step 2 on the side opposite to the double-sided adhesive sheet.

[0361] Figure 7A cross-sectional view for explaining a step of attaching the thermosetting film 4 having the supporting sheet 5 to the surface of the plurality of semiconductor chips CP opposite to the adhesive layer ( X2 ).

[0362] Thermosetting film 4 is a thermosetting film obtained by film-forming a resin composition containing at least a thermosetting resin, and can be used as an adhesive when mounting the semiconductor chip CP on a substrate. Thermosetting film 4 can contain a curing agent for the thermosetting resin, a thermoplastic resin, an inorganic filler, a curing accelerator, etc. as needed.

[0363] As the thermosetting film 4 , for example, a thermosetting film generally used as a die bonding film, a die attach film, or the like can be used.

[0364] The thickness of the thermosetting film 4 is not particularly limited, but is usually 1 to 200 μm, preferably 3 to 100 μm, and more preferably 5 to 50 μm.

[0365] The support sheet 5 may be made of any material as long as it can support the thermosetting film 4, and examples thereof include resins, metals, and paper materials listed as the non-heat-expandable base material layer (Y2) of the double-sided PSA sheet (A1).

[0366] (Separation process)

[0367] The method for manufacturing a semiconductor device of this embodiment preferably includes, after step 2 or step 3, one or more separation steps selected from a support separation step of separating the double-sided adhesive sheet from the support and an object separation step of separating the double-sided adhesive sheet from the ground object.

[0368] In the separation process, when the adhesive layer to which the adherend is attached has a mechanism of action that reduces the adhesive force, it is preferred to separate the adherend after performing a treatment for reducing the adhesive force. For example, when the adhesive layer is an adhesive layer that reduces the adhesive force by thermal expansion, the adherend can be separated after the adhesive force of the adhesive layer is reduced by heating, and when the adhesive layer is an adhesive layer that reduces the adhesive force by energy ray irradiation, the adherend can be separated after the adhesive force is reduced by energy ray irradiation.

[0369] Figure 8 A cross-sectional view illustrating a support separation step of separating the pressure-sensitive adhesive layer (X1) of the double-sided pressure-sensitive adhesive sheet (A) from the support S by heating the double-sided pressure-sensitive adhesive sheet (A) is shown.

[0370] The heating temperature of the double-sided adhesive sheet (A) is higher than the expansion starting temperature (t) of the heat-expandable particles, preferably "a temperature higher than the expansion starting temperature (t)", more preferably "expansion starting temperature (t) + 2°C" or higher, further preferably "expansion starting temperature (t) + 4°C" or higher, and further preferably "expansion starting temperature (t) + 5°C" or higher. In addition, from the viewpoint of energy saving and suppression of thermal changes in the adherend during heat peeling, the heating temperature of the double-sided adhesive sheet (A) is within a range of less than 125°C, preferably "expansion starting temperature (t) + 50°C" or lower, more preferably "expansion starting temperature (t) + 40°C" or lower, and further preferably "expansion starting temperature (t) + 20°C" or lower.

[0371] From the viewpoint of suppressing thermal changes in the adherend, the heating temperature of the double-sided adhesive sheet (A) is preferably lower than 125°C, more preferably lower than 120°C, further preferably lower than 115°C, further preferably lower than 110°C, and further preferably lower than 105°C, within a range above the expansion starting temperature (t). In particular, when the heating temperature of the double-sided adhesive sheet (A) is lower than 125°C, unintended curing of the thermosetting film can be suppressed when the above step 3 is performed.

[0372] Fig. 9 A cross-sectional view illustrating an object separation step of separating the pressure-sensitive adhesive layer ( X2 ) of the double-sided pressure-sensitive adhesive sheet (A) from a plurality of semiconductor chips CP is shown.

[0373] The method of separating the adhesive layer (X2) from the plurality of semiconductor chips CP can be appropriately selected according to the type of the adhesive layer (X2). For example, when the adhesive layer (X2) is an adhesive layer whose adhesive strength is reduced by irradiation with energy rays, separation can be performed after irradiating the adhesive layer (X2) with energy rays to reduce the adhesive strength.

[0374] Through the above steps, a plurality of semiconductor chips CP bonded to the thermosetting film 4 can be obtained.

[0375] Next, the thermosetting film 4 with the plurality of semiconductor chips CP attached is preferably cut into the same shape as the semiconductor chip CP to obtain semiconductor chips CP with thermosetting film 4. The thermosetting film 4 can be cut by laser cutting, sheet expansion, fusing, or the like.

[0376] Fig.10 The semiconductor chip CP with the thermosetting film 4 divided into the same shape as the semiconductor chip CP is shown.

[0377] The semiconductor chip CP with the thermosetting film 4 is further appropriately subjected to a chip expansion process for expanding the interval between the semiconductor chips CP, a rearrangement process for arranging the plurality of semiconductor chips CP after the interval is expanded, a reversal process for reversing the front and back surfaces of the plurality of semiconductor chips CP, etc. as needed, and then is attached (chip bonding) to the substrate from the thermosetting film 4 side. Thereafter, the thermosetting film 4 can be thermally cured to bond the bonded semiconductor chip to the substrate.

[0378] It should be noted that in Figures 3 to 10 In the description, a method of carrying out each process by pasting a semiconductor chip W on the adhesive layer (X2) of a double-sided adhesive sheet (A) and pasting a support body S on the adhesive layer (X1) is used as an example, but the manufacturing method of the semiconductor device of the present embodiment may also be a method of carrying out each process by pasting a semiconductor chip W on the adhesive layer (X1) of a double-sided adhesive sheet (A) and pasting a support body S on the adhesive layer (X2).

[0379] Example

[0380] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. It should be noted that the physical property values ​​in each example are values ​​measured by the following methods.

[0381] [Weight average molecular weight (Mw)]

[0382] The values ​​measured using a gel permeation chromatography apparatus (manufactured by Tosoh Corporation, product name “HLC-8320GPC”) under the following conditions and converted to standard polystyrene were used.

[0383] (Measurement conditions)

[0384] Column: "TSKgel guardcolumn SuperHzH", "TSKgel SuperHZM-M", "TSKgelSuperHZM-M", "TSKgel SuperHZ2000" connected in sequence (all manufactured by Tosoh Corporation)

[0385] Column temperature: 40℃

[0386] ·Developing solvent: tetrahydrofuran

[0387] Standard product: Polystyrene

[0388] Injection volume: 20μl

[0389] Flow rate: 0.35mL / min

[0390] Detector: Differential refractometer

[0391] [Thickness of each layer]

[0392] The measurement was performed at 23° C. using a constant pressure thickness gauge manufactured by Teclock Co., Ltd. (model number: “PG-02J”, standard specification: in accordance with JIS K6783, Z1702, and Z1709).

[0393] [The average particle size of the heat-expandable particles (D 50 )、90% particle size (D 90 )]

[0394] The particle distribution of the heat-expandable particles before expansion at 23°C is measured using a laser diffraction particle size distribution measuring device (e.g., manufactured by Malvern, product name "Mastersizer 3000"). Then, the particle sizes corresponding to the 50% and 90% cumulative volume frequencies calculated from the smaller particle size of the particle distribution are respectively taken as the "average particle size (D 50 )” and “90% particle size of heat-expandable particles (D 90 )”.

[0395] [Storage modulus E'(23) of non-heat-expandable substrate layer (Y2) at 23°C]

[0396] The non-heat-expandable substrate layer (Y2) cut into 30 mm long × 5 mm wide was used as a test sample, and the storage modulus E' at 23°C was measured using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name "DMAQ800") under the conditions of test start temperature 0°C, test end temperature 200°C, heating rate 3°C / min, vibration frequency 1 Hz, and amplitude 20 μm. As a result, the storage modulus E' (23) of the PET film as the non-heat-expandable substrate layer (Y2) described later at 23°C was 2.27 × 10 9 Pa.

[0397] [Thickness uniformity of workpiece after back grinding (TTV)]

[0398] The thickness of the entire object after back grinding was measured with a measurement pitch of 10 mm using a thickness measuring device (manufactured by Hamamatsu Photonics Co., Ltd., trade name "C8870"). The average value and standard deviation of the thickness were calculated from the thickness of each point obtained, and a data group of thicknesses within the range of [average value - (standard deviation × 3)] or more and [average value + (standard deviation × 3)] or less was extracted, and the difference between the maximum thickness and the minimum thickness in the data group was calculated as TTV (Total Thickness Variation).

[0399] [Manufacturing of Double-Sided PSA Sheet]

[0400] In the following production examples, the details of the materials used in forming each layer are as follows.

[0401] <Adhesive resin>

[0402] Acrylic copolymer (A1): a solution containing an acrylic copolymer with a Mw of 600,000, wherein the acrylic copolymer has structural units derived from raw material monomers consisting of n-butyl acrylate (BA) / methyl methacrylate (MMA) / acrylic acid (AA) / 2-hydroxyethyl acrylate (HEA) = 86 / 8 / 1 / 5 (mass ratio), diluent: ethyl acetate, solid content concentration: 40% by mass

[0403] Acrylic copolymer (A2): a solution comprising an energy-ray-curable acrylic copolymer having a Mw of 500,000 obtained by reacting 2-methacryloyloxyethyl isocyanate (MOI) with an acrylic copolymer in such a manner that the addition rate to all hydroxyl groups in the acrylic copolymer is 90% by mole, the acrylic copolymer being an acrylic copolymer having structural units derived from raw material monomers consisting of n-butyl acrylate (BA) / methyl methacrylate (MMA) / 2-hydroxyethyl acrylate (HEA) = 52 / 20 / 28 (mass ratio), diluent: ethyl acetate, solid content concentration: 35% by mass

[0404] <Cross-linking agent>

[0405] Isocyanate crosslinking agent (i): a solution containing trimethylolpropane-modified toluene diisocyanate (product name: Takenate D-101E, manufactured by Mitsui Chemicals, Inc.), solid content concentration: 75% by mass

[0406] <Energy beam curable compound>

[0407] Energy beam curable compound (i): manufactured by Mitsubishi Chemical Corporation, product name: "SHIKOH UT-4332", multifunctional urethane acrylate

[0408] <Photopolymerization initiator>

[0409] Photopolymerization initiator (i): bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide

[0410] Photopolymerization initiator (ii): 1-hydroxycyclohexyl phenyl ketone

[0411] <Additives>

[0412] Phthalocyanine pigments

[0413] <Thermal expansion particles>

[0414] Heat-expandable particles: manufactured by Nouryon, product name "Expancel (registered trademark) 031-40" (DU type), expansion starting temperature (t) = 88°C, average particle size (D 50 )=12.6μm, 90% particle size (D 90 )=26.2μm

[0415] <Peeling material>

[0416] Heavy release film: A material obtained by providing a release agent layer formed of a silicone release agent on one side of a polyethylene terephthalate (PET) film, product name "SP-PET382150" manufactured by Lintec Corporation, thickness: 38 μm

[0417] Light release film: A material obtained by providing a release agent layer formed of a silicone release agent on one side of a PET film, product name "SP-PET381031" manufactured by Lintec Co., Ltd., thickness: 38 μm

[0418] Production Example 1

[0419] (1) Formation of adhesive layer (X1)

[0420] 0.74 parts by mass of an isocyanate crosslinking agent (i) was added to 100 parts by mass of the solid content of the acrylic copolymer (A1) (solid content ratio), diluted with toluene, and stirred until uniform to prepare an adhesive composition (x-1) having a solid content concentration (active ingredient concentration) of 25% by mass.

[0421] Thereafter, the prepared PSA composition (x-1) was applied onto the release surface of the heavy release film to form a coating film, and the coating film was dried at 100° C. for 60 seconds to form a PSA layer (X1) having a thickness of 5 μm.

[0422] (2) Formation of Adhesive Layer (X2)

[0423] To 100 parts by weight of the solid content of the acrylic copolymer (A2), 12 parts by weight (solid content ratio) of an energy-ray-curable compound (i), 1.1 parts by weight (solid content ratio) of an isocyanate crosslinking agent (i), and 1 part by weight (solid content ratio) of a photopolymerization initiator (i) were added, the mixture was diluted with toluene, and stirred until uniform, to prepare an adhesive composition (x-2) having a solid content concentration (active ingredient concentration) of 30% by weight.

[0424] Thereafter, the prepared PSA composition (x-2) was applied onto the release surface of the light release film to form a coating film, and the coating film was dried at 100° C. for 60 seconds to form a 20 μm thick PSA layer (X2).

[0425] (3) Preparation of solvent-free resin composition (y-1a)

[0426] 2-Hydroxyethyl acrylate was reacted with an isocyanate-terminated urethane prepolymer obtained by reacting an ester diol and isophorone diisocyanate (IPDI) to obtain a linear urethane prepolymer having ethylenically unsaturated groups at both ends as an oligomer having a weight average molecular weight (Mw) of 5,000.

[0427] Subsequently, 40 parts by mass (solid content ratio) of isobornyl acrylate (IBXA) and 20 parts by mass (solid content ratio) of phenylhydroxypropyl acrylate (HPPA) as energy-ray polymerizable monomers were added to 40 parts by mass (solid content ratio) of the above-synthesized urethane prepolymer, and 2.0 parts by mass (solid content ratio) of a photopolymerization initiator (ii) and 0.2 parts by mass (solid content ratio) of a phthalocyanine pigment as an additive and 20 parts by mass (solid content ratio) of cyclohexyl acrylate (CHA) were further added relative to the total amount (100 parts by mass) of the urethane prepolymer and the energy-ray polymerizable monomer to prepare an energy-ray curable composition.

[0428] Then, heat-expandable particles were blended into the energy-ray curable composition so that the content of the heat-expandable particles was 12.5% ​​by mass relative to the total mass (100% by mass) of the obtained heat-expandable substrate layer (Y1), thereby preparing a solvent-free resin composition (y-1a) containing no solvent.

[0429] (4) Formation of a substrate laminate in which a heat-expandable substrate layer (Y1) and a non-heat-expandable substrate layer (Y2) are laminated

[0430] A PET film (manufactured by Toyobo Co., Ltd., product name: "COSMOSHINE A4360", thickness: 50 μm) was prepared as a non-thermally expandable base material layer (Y2).

[0431] Thereafter, a solvent-free resin composition (y-1a) was applied on one side of the PET film so that the thickness of the formed heat-expandable base material layer (Y1) was 100 μm, thereby forming a coating film.

[0432] Then, an ultraviolet irradiation device (manufactured by Eyegraphics Co., Ltd., product name "ECS-401GX") and a high-pressure mercury lamp (manufactured by Eyegraphics Co., Ltd., product name "H04-L41") were used to irradiate the sample at an illumination of 160 mW / cm 2 , light intensity 500mJ / cm 2The coating film was cured by irradiating ultraviolet rays under the conditions of , and a substrate laminated body having a heat-expandable substrate layer (Y1) formed on a PET film as a non-heat-expandable substrate layer (Y2) was obtained. It should be noted that the above-mentioned illuminance and light quantity during ultraviolet irradiation are values ​​measured using an illuminance / light quantity meter (manufactured by Eyegraphics Co., Ltd., product name "UVPF-A2").

[0433] (5) Making double-sided adhesive sheets

[0434] The adhesive surface of the adhesive layer (X1) formed in the above (1) is bonded to the surface of the heat-expandable substrate layer (Y1) of the substrate laminate formed in the above (4). Thereafter, the adhesive surface of the adhesive layer (X2) formed in the above (2) is bonded to the surface of the PET film of the substrate laminate.

[0435] Thus, a double-sided PSA sheet with a release material having the following structure was produced.

[0436] <Heavy release film> / <Adhesive layer (X1), thickness: 5 μm> / <Thermal expandable substrate layer (Y1), thickness: 100 μm> / <Non-thermal expandable substrate layer (Y2), thickness: 50 μm> / <Adhesive layer (X2), thickness: 20 μm> / <Light release film>

[0437] [Manufacturing of semiconductor devices]

[0438] Example 1

[0439] (1) Preparation of laminated body

[0440] The light release film on the adhesive layer (X2) side of the double-sided adhesive sheet with release material produced above was peeled off, and the object to be processed (a double-sided mirror silicon wafer with a diameter of 12 inches and a thickness of 780 μm) was attached to the exposed adhesive layer (X2).

[0441] In addition, the heavy release film on the adhesive layer (X1) side of the double-sided adhesive sheet was peeled off, and a support (a double-sided mirror silicon wafer with a diameter of 12 inches and a thickness of 450 μm) was attached to the exposed adhesive layer (X1) to produce a laminate having a support, a double-sided adhesive sheet and a processing object in this order.

[0442] In addition, for laminating the object to be processed and the support, a tape laminator for back grinding (manufactured by Lintec Corporation, device name “RAD-3510F / 12”) was used.

[0443] (2) Support body grinding

[0444] The laminated object obtained above was fixed to a chuck table, and the support was ground using a grinder (Disco Co., Ltd., trade name "DGP8761"). The support was ground until the thickness of the support, which was originally 450 μm before grinding, reached 400 μm.

[0445] (3) Grinding of workpieces

[0446] The support body ground in the above (2) was fixed to the chuck table, and the object to be processed was ground using a grinder (manufactured by Disco Co., Ltd., trade name "DGP8761"). It should be noted that the grinding of the object to be processed was performed until the thickness of the object to be processed, which was originally 780 μm before grinding, reached 50 μm. The TTV of the object to be processed after grinding was measured by the above method.

[0447] Example 2

[0448] The TTV of the object after grinding obtained by the same method as in Example 1 except that the object was ground until the thickness of the object before grinding, which was originally 780 μm, reached 30 μm, was measured by the above method.

[0449] Comparative Example 1

[0450] “(1) Preparation of a laminated body” was performed in the same procedure as in Example 1, “(2) Support body grinding” was not performed, and “(3) Object grinding” was performed in the same procedure as in Example 1.

[0451] Comparative Example 2

[0452] The TTV of the object after grinding obtained by the same method as in Comparative Example 1 was measured by the above method except that in Comparative Example 1, "(3) grinding of the object" was performed until the thickness of the object before grinding, which was 780 μm, reached 30 μm.

[0453] [Table 1]

[0454]

[0455] According to the results in Table 1, the TTV of the objects after grinding in Examples 1 and 2 in which the support grinding process was performed was smaller than that in Comparative Examples 1 and 2 in which the support grinding process was not performed.

Claims

1. A method for manufacturing a semiconductor device, comprising the following steps 1 and 2 in sequence: Step 1: a step of producing a laminate having a support, a double-sided adhesive sheet, and an object to be processed in this order, Step 2: a step of grinding the object to be processed while the support of the stack is fixed. in, The step 1 includes a support grinding process of grinding the support adhered to the double-sided pressure-sensitive adhesive sheet.

2. The method for manufacturing a semiconductor device according to claim 1, wherein: The support grinding process is a process of grinding the support adhered to the other surface of the double-sided adhesive sheet while the object to be processed adhered to one surface of the double-sided adhesive sheet is fixed.

3. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein: The support is at least one selected from a silicon wafer and a glass wafer.

4. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein: The thickness of the support body after the support body grinding treatment is 200 to 1500 μm.

5. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein: The support has a laminated structure including a support layer and a peelable sheet laminated on one side of the support layer. The support is attached to the double-sided adhesive sheet in such a manner that the removable sheet becomes the outermost surface. The support grinding treatment is a step of grinding the releasable sheet.

6. The method for manufacturing a semiconductor device according to claim 5, wherein: The support layer is at least one selected from a silicon wafer and a glass wafer.

7. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein: The double-sided pressure-sensitive adhesive sheet contains particles.

8. The method for manufacturing a semiconductor device according to claim 7, wherein: The particles are heat-expandable particles.

9. The method for manufacturing a semiconductor device according to claim 8, wherein: The double-sided adhesive sheet comprises an adhesive layer (X1), a substrate layer (Y), and an adhesive layer (X2) in this order, and the adhesive layer (X1) is a heat-expandable layer containing the heat-expandable particles.

10. The method for manufacturing a semiconductor device according to claim 8, wherein: The double-sided adhesive sheet comprises an adhesive layer (X1), a substrate layer (Y), and an adhesive layer (X2) in this order, wherein the substrate layer (Y) is a heat-expandable layer containing the heat-expandable particles.

11. The method for manufacturing a semiconductor device according to claim 10, wherein: The substrate layer (Y) is a substrate laminate formed by laminating a heat-expandable substrate layer (Y1) containing heat-expandable particles and a non-heat-expandable substrate layer (Y2), The double-sided pressure-sensitive adhesive sheet includes the pressure-sensitive adhesive layer (X1), the heat-expandable substrate layer (Y1), the non-heat-expandable substrate layer (Y2), and the pressure-sensitive adhesive layer (X2) in this order.

12. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein: The object to be processed is a semiconductor wafer.

13. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein: Prior to step 2, at least one step selected from the group consisting of a step of forming grooves on the surface of the object on the double-sided adhesive sheet side and a step of forming a modified region inside the object is performed. The step 2 is a step of grinding the object to be processed in a state where the support of the stack is fixed, and dividing the object to be processed into individual pieces with the groove or the modified region as a starting point.

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