Wafer processing method

Abstract

Provided is a method of treating a wafer in the state where the wafer is fixed on a support plate with an adhesive composition. Although the wafer is treated by a chemical, heating, or exothermic treatment, the method achieves sufficient adhesiveness during the step of treating a surface of the wafer and allows detachment of the support plate from the wafer without damaging the wafer or leaving the adhesive on the wafer after the wafer treating step. The method of treating a wafer of the present invention includes the steps of: fixing a wafer on a support plate via an adhesive composition containing a curable adhesive component to be crosslinked and cured by light irradiation or heating; crosslinking and curing the curable adhesive component by light irradiation or heating of the adhesive composition; treating a surface of the wafer fixed on the support plate by a chemical, heating, or exothermic treatment; and detaching the support plate from the treated wafer.

Claims

1. A method of treating a wafer, comprising the steps of: obtaining a double-sided adhesive tape having an adhesive layer formed from an adhesive composition containing a curable adhesive component to be crosslinked and cured by light irradiation or heating; fixing a wafer on a support plate via the double-sided adhesive tape; crosslinking and curing the curable adhesive component by light irradiation at an integrated illuminance of 300 millijoule or more or heating of the adhesive composition; treating a surface of the wafer fixed on the support plate by a chemical, heating, or exothermic treatment after the crosslinking and the curing of the curable adhesive component by light irradiation; and detaching the support plate from the treated wafer, wherein the adhesive composition has a storage shear modulus at 25 C. of 2.010.sup.5 to 10.sup.8 Pa, as measured by dynamic viscoelasticity measurement under shear mode and continuous temperature rise from 50 C. to 300 C., after the step of crosslinking and curing the curable adhesive component, wherein the adhesive composition comprises a gas generating agent that generates a gas by stimulation, and, in the step of detaching the support plate, the support plate is detached from the wafer by stimulating the treated wafer and thereby causing gas generation from the gas generating agent, and wherein the crosslinking and curing of the curable adhesive component does not cause the support plate to detach from the wafer.

Description

DESCRIPTION OF EMBODIMENTS

(1) Some aspects of the present invention are described in more detail below referring to examples which do not intend to limit the present invention.

(2) (Synthesis of Resins A to L)

(3) A reactor equipped with a thermometer, a stirrer, and a condenser tube was prepared and charged with 2-ethylhexyl acrylate (94 parts by weight) as a (meth)acrylic acid alkyl ester, hydroxyethyl methacrylate (6 parts by weight) as a functional group-containing monomer, lauryl mercaptan (0.01 parts by weight), and ethyl acetate (80 parts by weight). The reactor was heated and thereby was refluxed. Then, to the reactor was added 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane (0.01 parts by weight) as a polymerization initiator, whereby the polymerization was started under reflux. At one hour and at two hours from the starting of the polymerization, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane (0.01 parts by weight) was further added to the reactor. At four hours from the starting of the polymerization, t-hexylperoxy pivalate (0.05 parts by weight) was added thereto, and the polymerization reaction was continued. At eight hours from the starting of the polymerization, an ethyl acetate solution of a functional group-containing (meth)acrylic polymer having a solids content of 55% by weight and a weight average molecular weight of 600000 was obtained.

(4) Subsequently, 3.5 parts by weight of 2-isocyanatoethyl methacrylate as a functional group-containing unsaturated compound was added for 100 parts by weight of the resin solids content of the obtained ethyl acetate solution of a functional group-containing (meth)acrylic polymer, whereby the mixture was reacted. Thus, a photocurable adhesive (resin A) was obtained.

(5) Resins B to L were synthesized in the same manner as in the synthesis of the resin A except that the materials shown in Table 1 were used as the (meth)acrylic acid alkyl ester, functional group-containing monomer, and functional group-containing unsaturated compound. In resin I, pentaerythritol triacrylate (5 parts by weight) was also used as a polyfunctional oligomer and the polymerization was initiated.

(6) TABLE-US-00001 TABLE 1 Functional group-containing (meth)acrylic polymer Amont of monomer (parts by weight) Acrylic Amount of functional group-containing acid Poly- unsaturated compound (for 100 parts by weight alkyl Functional group-containing monomer functional Amount of Weight of the resin solids content of the functional ester Hydroxy- Iso- oligomer radical average group-containing (meth)acrylic polymer) 2-Ethyl- ethyl Glycidyl cyanate Penta- polymerizable molecular 2-Isocyanato- hexyl meth- Acrylic meth- ethyl erythritol unsaturated weight ethyl Glycidyl Hydroxyethyl acrylate acrylate acid acrylate acrylate triacrylate bond (meq/g) (10000) methacrylate methacrylate methacrylate Resin A 94 6 0.30 60 3.5 Resin B 90 10 0.30 85 3.5 Resin C 80 20 0.15 85 1.5 Resin D 80 20 0.40 90 5 Resin E 80 20 0.70 82 10 Resin F 80 20 1.10 85 15 Resin G 80 18 2 0.40 72 5 Resin H 80 10 10 0.40 60 5 Resin I 90 5 5 0.30 105 3.5 Resin J 95 5 0.40 75 5 Resin K 90 10 0.30 85 3.5 Resin L 95 5 0.30 80 3.5

Example 1

(1) Production of Adhesive Tape

(7) A photopolymerization initiator (Esacure One, available from DKSH Japan K.K.) in an amount of 1 part by weight was mixed with an ethyl acetate solution of the resin A for 100 parts by weight of the resin solids content of the solution.

(8) The resulting ethyl acetate solution of the adhesive composition was applied with a doctor blade to a 50-m-thick transparent polyethylene naphthalate film having a corona treated surface (to the corona treated surface) such that the resulting dry coating film would have a 30 m thickness. The resulting film coated with the composition was heated at 110 C. for five minutes and thereby the applied liquid was dried. Then, the film was left to stand and cured at 40 C. for three days, whereby an adhesive tape was obtained.

(2) Evaluation of the Modulus of Elasticity of Adhesive Composition after Ultraviolet Light Irradiation

(9) A sample for evaluation was prepared as follows. The ethyl acetate solution of the adhesive composition was applied with a doctor blade to a 50-m-thick transparent polyethylene naphthalate film having a corona treated surface (to the corona treated surface) such that the resulting dry coating film would have a 500 m thickness. The applied liquid was dried by heating at 110 C. for five minutes, and the resulting film was left to stand and cured at 40 C. for three days. The resulting adhesive tape was cut into a rectangle having a length of 0.6 cm and a width of 1.0 cm. This rectangular piece was used as a sample for evaluation. The surface of the sample was irradiated with 365 nm wavelength ultraviolet light at an irradiation intensity on the tape of 80 mW/cm.sup.2 for two minutes using an ultrahigh pressure mercury lamp. Thereby, the adhesive component was crosslinked and cured. The storage modulus at 25 C. of the cured sample for evaluation, as measured by dynamic viscoelasticity measurement under shear mode and continuous temperature rise from 50 C. to 300 C. at an angular frequency of 10 Hz, was determined.

(3) Evaluation for Chemical Resistance and Heat Resistance after Ultraviolet Light Irradiation

(10) The resulting adhesive tape was cut into a 20-cm-diameter circle. The circular adhesive tape was adhered to a silicon wafer having a diameter of 20 cm and a thickness of about 750 m under vacuum. The other side of the adhesive tape (the side without the silicon wafer) was adhered to a quartz glass plate having a diameter of 20 cm and a thickness of 1 mm under vacuum, whereby a laminate was formed.

(11) The wafer side of the resulting laminate was subjected to grind grinding and polishing such that the wafer had a 50 m thickness.

(12) Then, the adhesive component was crosslinked and cured by irradiation with 365 nm wavelength ultraviolet light at an irradiation intensity on the glass plate surface of 80 mW/cm.sup.2 for one minute from the glass plate side using an ultrahigh pressure mercury lamp.

(13) (3-1)

(14) The laminate including the crosslinked and cured adhesive component was evaluated for the chemical resistance to an acid, base, and organic solvent.

(15) Specifically, a solution of Standard Clean 1 (SC 1) was prepared as an acid, and the laminate including the crosslinked and cured adhesive component was immersed in the SC 1 solution at 60 C. for one hour. The laminate was taken out after the immersion, and the bonded surface between the adhesive tape and the silicon wafer was visually observed from the quartz-glass-plate side. The case where no partial detachment was observed on the whole surface was evaluated as good (), and the case where partial detachment was observed or the adhesive tape was detached was evaluated as poor (x).

(16) The same evaluations were conducted using a 2.38% TMAH aqueous solution as a base and acetone as an organic solvent. Table 2 shows the results.

(17) (3-2)

(18) The laminate including the crosslinked and cured adhesive component was evaluated for heat resistance by the following method.

(19) Specifically, a thermal treatment was performed on the laminate including the crosslinked and cured adhesive component at 200 C. for one hour. The thermally treated laminate was taken out and cooled to 25 C. Then, the bonded surface between the adhesive tape and the silicon wafer was visually observed from the quartz-glass-plate side. The case where no partial detachment was observed on the whole surface was evaluated as good (), and the case where partial detachment was observed or the adhesive tape was detached was evaluated as poor (x).

(20) The same evaluations were conducted on a 700-m-thick silicon wafer (circuit wafer) having a circuit with a level difference of about 5 m.

(21) Table 2 shows the results.

(4) Evaluation of Adhesive Residue after Thermal Treatment

(22) The resulting adhesive tape was cut into a 20-cm-diameter circle and was adhered to a silicon wafer having a diameter of 20 cm and a thickness of about 750 m under vacuum. The other side of the adhesive tape (the side without the silicon wafer) was adhered to a quartz glass plate having a diameter of 20 cm and a thickness of 1 mm under vacuum, whereby a laminate was formed.

(23) The wafer side of the resulting laminate was subjected to grind grinding and polishing until the thickness of the wafer was 50 m.

(24) The adhesive component was then crosslinked and cured by irradiation with 365 nm wavelength ultraviolet light at an irradiation intensity on the surface of the glass plate of 80 mW/cm.sup.2 for one minute from the glass-plate side using an ultrahigh pressure mercury lamp.

(25) The laminate including the crosslinked and cured adhesive component was subjected to thermal treatment at 200 C. for two hours. A dicing tape was adhered to the thermally treated silicon wafer on the side without the adhesive tape, and the wafer was fixed by suction. Then, the quartz glass plate and the adhesive tape were detached from the wafer.

(26) The adhesive tape-detached surface of the silicon wafer was visually observed. The case where no adhesive was left was evaluated as excellent (), the case where the area having adhesive residue was less than 5% of the whole area was evaluated as good (), and the case where the area having adhesive residue was 5% or more of the whole area was evaluated as poor (x).

(27) Also, the adhesive tape-detached surface of the silicon wafer was observed with an optical microscope at a magnification of 100 times. The case where no adhesive was found in the field of view was evaluated as excellent (), the case where the area having adhesive residue was less than 5% of the whole field of view was evaluated as good (), and the case where the area having adhesive residue was 5% or more of the whole field of view was evaluated as poor (x).

(28) Table 2 shows the results.

Examples 2 to 25, Comparative Example 1

(29) An adhesive composition and an adhesive tape were obtained in the same manner as in Example 1, except that the kind of the resin was as shown in Table 2, and, in the preparation of the adhesive composition, (meth)acrylic group-containing silicone compound (EBECRYL 350, (acrylic equivalent: 2) or EBECRYL 1360 (acrylic equivalent: 6), available from DAICEL-ALLNEX LTD.), and a plasticizer (UN-2600, UN-5500, or UN-7700, available from Negami Chemical Industrial Co., Ltd.) were further added according to Table 2. The resulting adhesive tape was subjected to the same evaluations as in Example 1.

(30) In Comparative Example 1, the adhesive component was not crosslinked or cured by ultraviolet light irradiation in the evaluation for chemical resistance, heat resistance, and adhesive residue.

(31) Table 2 shows the results.

(32) TABLE-US-00002 TABLE 2 Photopolymerization initiator Silicone compound Plasticizer Modulus of Amount Amount Amount Ultraviolet elasticity after (parts by Trade (parts by Trade (parts by light ultraviolet light Resin weight) name weight) name weight) irradiation irradiation (10.sup.5 Pa) Example 1 Resin A 1 Irradiated 28 Example 2 Resin A 1 Irradiated 43 Example 3 Resin A 1 Irradiated 37 Example 4 Resin A 1 EBECRYL350 0.5 Irradiated 33 Example 5 Resin A 1 EBECRYL350 10 Irradiated 38 Example 6 Resin A 1 EBECRYL350 30 Irradiated 49 Example 7 Resin A 1 EBECRYL1360 15 Irradiated 43 Example 8 Resin A 1 UN5500 5 Irradiated 46 Example 9 Resin A 1 UN5500 20 Irradiated 47 Example 10 Resin A 1 UN5500 50 Irradiated 42 Example 11 Resin A 1 UN2600 20 Irradiated 40 Example 12 Resin A 1 UN7700 20 Irradiated 41 Example 13 Resin A 1 EBECRYL350 5 UN5500 20 Irradiated 42 Example 14 Resin A 0.2 EBECRYL350 5 UN5500 20 Irradiated 31 Example 15 Resin B 1 EBECRYL350 5 UN5500 20 Irradiated 28 Example 16 Resin C 1 EBECRYL350 5 UN5500 20 Irradiated 43 Example 17 Resin D 1 EBECRYL350 5 UN5500 20 Irradiated 51 Example 18 Resin E 1 EBECRYL350 5 UN5500 20 Irradiated 79 Example 19 Resin F 1 EBECRYL350 5 UN5500 20 Irradiated 125 Example 20 Resin G 1 EBECRYL350 5 UN5500 20 Irradiated 49 Example 21 Resin H 1 EBECRYL350 10 UN5500 20 Irradiated 52 Example 22 Resin I 1 EBECRYL350 5 UN5500 20 Irradiated 24 Example 23 Resin J 1 EBECRYL350 5 UN5500 20 Irradiated 47 Example 24 Resin K 1 EBECRYL350 5 UN5500 20 Irradiated 26 Example 25 Resin L 1 EBECRYL350 5 UN5500 20 Irradiated 23 Comparative Resin A 1 Not 0.9 Example 1 irradiated Adhesive residue Adhesive residue Chemical resistance Heat resistance evaluation (visual evaluation evaluation evaluation observation) (microscope) Organic Bare Circuit Bare Circuit Bare Circuit Acid Base solvent wafer wafer wafer wafer wafer wafer Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Example 20 Example 21 Example 22 Example 23 Example 24 Example 25 Comparative X X X X X X X X X Example 1

Example 26

(1) Production of Adhesive Tape

(33) For 100 parts by weight of the resin solids content of the ethyl acetate solution of the resin A, 1 part by weight of a photopolymerization initiator (Esacure One, available from DKSH Japan K.K.), 5 parts by weight of a silicone compound (EBECRYL 350, available from DAICEL-ALLNEX LTD.), 20 parts by weight of a plasticizer (UN-5500, available from Negami Chemical Industrial Co., Ltd.) and 10 parts by weight of 5-phenyl-1H-tetrazole as a gas generating agent were mixed with the ethyl acetate solution of the resin A.

(34) The resulting ethyl acetate solution of the adhesive composition was applied with a doctor blade to a 50-m-thick transparent polyethylene naphthalate film having a corona treated surface (to the corona treated surface) such that the resulting dry coating film would have a 30 m thickness, and the applied solution was heated and dried at 110 C. for five minutes. Subsequently, the film was left to stand and cured at 40 C. for three days, whereby an adhesive tape was obtained.

(2) Evaluation for Modulus of Elasticity of Adhesive Composition after Ultraviolet Light Irradiation

(35) A sample for evaluation was prepared as follows. The ethyl acetate solution of the adhesive composition was applied with a doctor blade to a 50-m-thick transparent polyethylene naphthalate film having a corona treated surface (to the corona treated surface) such that the resulting dry coating film would have a 500 m thickness. The applied solution was heated and dried at 110 C. for five minutes. Then, the film was left to stand and cured at 40 C. for three days. The resulting adhesive tape was cut into a rectangle having a length of 0.6 cm and a width of 1.0 cm. This rectangular piece of the tape was used as a sample for evaluation. Next, the adhesive component of the sample was crosslinked and cured by irradiation with 365 nm wavelength ultraviolet light at an irradiation intensity on the surface of the tape of 80 mW/cm.sup.2 for two minutes using an ultrahigh pressure mercury lamp. The storage modulus at 25 C. of the cured sample for evaluation, as measured by dynamic viscoelasticity measurement under shear mode and continuous temperature rise from 50 C. to 300 C. at an angular frequency of 10 Hz, was determined.

(3) Evaluation for Chemical Resistance and Heat Resistance after Ultraviolet Light Irradiation

(36) The resulting adhesive tape was cut into a 20-cm-diameter circle and was adhered to a silicon wafer having a diameter of 20 cm and a thickness of about 750 m under vacuum. The other side of the adhesive tape (the side without the silicon wafer) was adhered to a quartz glass plate having a diameter of 20 cm and a thickness of 1 mm under vacuum, whereby a laminate was formed.

(37) The wafer-side of the obtained laminate was subjected to grind grinding and polishing until the wafer had a thickness of 50 m.

(38) Subsequently, the adhesive component of the laminate was crosslinked and cured by irradiation with 365 nm wavelength ultraviolet light at an irradiation intensity on the surface of the glass plate of 80 mW/cm.sup.2 for one minute from the glass plate side using an ultrahigh pressure mercury lamp.

(39) (3-1)

(40) The laminate including the crosslinked and cured adhesive component was evaluated for the chemical resistance to an acid, base, and organic solvent by the following method.

(41) Specifically, a Standard Clean 1 (SC 1) solution was prepared as an acid, and the laminate including the crosslinked and cured adhesive component was immersed in the SC 1 solution at 60 C. for one hour. The laminate was taken out after the immersion, and the bonded surface between the adhesive tape and the silicon wafer was visually observed from the quartz glass plate side. The case where no partial detachment was observed on the whole surface was evaluated as good (), and the case where partial detachment was observed or the adhesive tape was detached was evaluated as poor (x).

(42) The same evaluations were conducted using a 2.38% TMAH aqueous solution as a base and acetone as an organic solvent.

(43) Table 3 shows the results.

(44) (3-2)

(45) The laminate including the crosslinked and cured adhesive component was evaluated for heat resistance by the following method.

(46) Specifically, the laminate including the crosslinked and cured adhesive component was subjected to thermal treatment at 200 C. for one hour. The thermally treated laminate was taken out and the temperature thereof was cooled to 25 C. Then, the bonded surface between the adhesive tape and the silicon wafer was visually observed from the quartz glass plate side. The case where no partial detachment was observed on the whole surface was evaluated as good (), and the case where partial detachment was observed or the adhesive tape was detached was evaluated as poor (x).

(47) Table 3 shows the results.

(4) Evaluation of Adhesive Residue after Thermal Treatment

(48) The obtained adhesive tape was cut into a 20-cm-diameter circle and was adhered to a silicon wafer having a diameter of 20 cm and a thickness of about 750 m under vacuum. The other side of the adhesive tape (the side without the silicon wafer) was adhered to a quartz glass plate having a diameter of 20 cm and a thickness of 1 mm under vacuum, whereby a laminate was formed.

(49) The wafer side of the resulting laminate was subjected to grind grinding and polishing until the wafer had a thickness of 50 m.

(50) Subsequently, the adhesive component of the laminate was crosslinked and cured by irradiation with 365 nm wavelength ultraviolet light at an irradiation intensity on the surface of the glass plate of 80 mW/cm.sup.2 for one minute from the glass plate side using an ultrahigh pressure mercury lamp.

(51) The laminate including the crosslinked and cured adhesive component was subjected to thermal treatment at 200 C. for one hour. A dicing tape was adhered to the thermally treated silicon wafer on the side without the adhesive tape, and the silicon wafer was fixed by suction. The silicon wafer was irradiated with light having an illuminance of 254 nm and an intensity of 70 mW/cm.sup.2 for 150 seconds from the Tempax glass side using an ultrahigh pressure mercury lamp. Then, the quartz glass plate and the adhesive tape were detached from the wafer.

(52) The adhesive tape-detached surface of the silicon wafer was visually observed. The case where no adhesive was left was evaluated as excellent (), the case where the area having adhesive residue was less than 5% of the whole area was evaluated as good (), and the case where the area having adhesive residue was 5% or more of the whole area was evaluated as poor (x).

(53) Also, the adhesive tape-detached surface of the silicon wafer was observed with an optical microscope at a magnification of 100 times. The case where no adhesive was left in the field of view was evaluated as excellent (), the case where the area having adhesive residue was less than 5% of the whole field of view was evaluated as good (), and the case where the area having adhesive residue was 5% or more of the whole field of view was evaluated as poor (x).

(54) Table 3 shows the results.

Examples 27 to 45, Comparative Example 2

(55) An adhesive composition and an adhesive tape were obtained in the same manner as in Example 26, except that the kind of the resin and the kind and the amount of the gas generating agent to be blended with the adhesive composition were as shown in Table 3. The obtained adhesive tape was subjected to the same evaluations as in Example 26. In Comparative Example 2, the adhesive component was not crosslinked or cured by ultraviolet light irradiation in the evaluation for chemical resistance, heat resistance, and adhesive residue.

(56) TABLE-US-00003 TABLE 3 Photo- polymerization Silicone initiator compound Plasticizer Gas generating agent Modulus of Amount Amount Amount Amount Ultraviolet elasticity after (parts by (parts by (parts by Compound (parts by light irradiation Resin weight) weight) weight) name weight) irradiation (10.sup.5 Pa) Example 26 Resin A 1 5 20 5-Phenyl-1H-tetrazole 10 Irradiated 44 Example 27 Resin A 1 5 20 4,5 Ditetrazolyl- 10 Irradiated 45 [1,2,3]triazole Example 28 Resin A 1 5 20 1-(p-Ethoxyphenyl)-5- 10 Irradiated 43 mercaptotetrazole Example 29 Resin A 1 5 20 1-(4-Benzamide)-5- 10 Irradiated 43 mercaptotetrazole Example 30 Resin A 1 5 20 5-Tolyltetrazole 10 Irradiated 46 Example 31 Resin A 1 5 20 2-(5-Tetrazoyl)aniline 10 Irradiated 45 Example 32 Resin A 1 5 20 5-(m-Aminophenyl)tetrazole 10 Irradiated 46 Example 33 Resin A 1 5 20 5-Acetamide tetrazole 10 Irradiated 47 Example 34 Resin A 1 5 20 N-(1H tetrazol-5-yl)-n- 10 Irradiated 48 octane amide Example 35 Resin A 1 5 20 1-Cyclohexyl-5-chlorobutyl 10 Irradiated 44 tetrazole Example 36 Resin A 1 5 20 Bistetrazole piperazine salt 10 Irradiated 44 Example 37 Resin A 1 5 20 Bistetrazole diammonium salt 10 Irradiated 45 Example 38 Resin A 1 5 20 Bistetrazole disodium salt 10 Irradiated 48 Example 39 Resin A 1 5 20 Bistetrazole monohydrate 10 Irradiated 42 Example 40 Resin A 1 5 20 Bistetrazole monoammonium 10 Irradiated 43 Example 41 Resin A 1 5 20 5-Aminotetrazole monohydrate 10 Irradiated 42 Example 42 Resin A 1 5 20 1-Methyl-5-mercaptotetrazole 10 Irradiated 43 Example 43 Resin A 1 5 20 Bistetrazole disodium salt 50 Irradiated 43 Example 44 Resin C 1 5 20 Bistetrazole disodium salt 10 Irradiated 42 Example 45 Resin H 1 5 20 Bistetrazole disodium salt 10 Irradiated 44 Comparative Resin A 1 5 20 5-Phenyl-1H-tetrazole 10 Not 0.6 Example 2 irradiated Adhesive residue Adhesive residue Chemical resistance Heat resistance evaluation (visual evaluation evaluation evaluation observation) (microscope) Organic Bare Circuit Bare Circuit Bare Circuit Acid Base solvent wafer wafer wafer wafer wafer wafer Example 26 Example 27 Example 28 Example 29 Example 30 Example 31 Example 32 Example 33 Example 34 Example 35 Example 36 Example 37 Example 38 Example 39 Example 40 Example 41 Example 42 Example 43 Example 44 Example 45 Comparative X X X X X X X X X Example 2

Example 46

(1) Production of Adhesive Tape

(57) For 100 parts by weight of the resin solids content of the ethyl acetate solution of the resin A, 1 part by weight of a thermal polymerization initiator (Perhexyl O, available from NOF Corporation) was mixed with the ethyl acetate solution of the resin A.

(58) The resulting ethyl acetate solution of the adhesive composition was applied with a doctor blade to a 50-m-thick transparent polyethylene naphthalate film having a corona treated surface (to the corona treated surface) such that the resulting dry coating film would have a 30 m thickness, and the applied solution was dried by heating at 80 C. for five minutes. Then, the film was left to stand and cured at 40 C. for three days, whereby an adhesive tape was obtained.

(2) Evaluation of Modulus of Elasticity of Adhesive Composition Crosslinked and Cured by Heating

(59) A sample for evaluation was prepared as follows. The ethyl acetate solution of the adhesive composition was applied with a doctor blade to a 50-m-thick transparent polyethylene naphthalate film having a corona treated surface (to the corona treated surface) such that the resulting dry coating film would have a 500 m thickness. The applied solution was heated and dried at 110 C. for five minutes. The resulting film was left to stand and cured at 40 C. for three days. The resulting adhesive tape was cut into a rectangle having a length of 0.6 cm and a width of 1.0 cm. This rectangular tape was used as a sample for evaluation. The adhesive component of the sample was crosslinked and cured by a thermal treatment at 100 C. for one hour. The storage modulus at 25 C. of the cured sample for evaluation, as measured by dynamic viscoelasticity measurement under shear mode and continuous temperature rise from 50 C. to 300 C. at an angular frequency of 10 Hz, was determined.

(3) Evaluation of Chemical Resistance and Heat Resistance after Heating

(60) The resulting adhesive tape was cut into a 20-cm-diameter circle and was adhered to a silicon wafer having a diameter of 20 cm and a thickness of about 750 m under vacuum. The other side of the adhesive tape (the side without the silicon wafer) was adhered to a quartz glass plate having a diameter of 20 cm diameter and a thickness of 1 mm under vacuum, whereby a laminate was formed.

(61) The wafer side of the resulting laminate was subjected to grind grinding and polishing until the wafer had a 50 m thickness.

(62) Then, the adhesive component of the laminate was crosslinked and cured by a thermal treatment at 100 C. for one hour.

(63) (3-1)

(64) The laminate including the crosslinked and cured adhesive component was evaluated for the chemical resistance to an acid, base, and organic solvent by the following method.

(65) Specifically, a Standard Clean 1 (SC1) solution as an acid was prepared, and the laminate including the crosslinked and cured adhesive component was immersed in the SC 1 solution at 60 C. for one hour. The laminate was taken out after the immersion, and the bonded surface between the adhesive tape and the silicon wafer was visually observed from the quartz glass plate side. The case where no partial detachment was observed on the whole surface was evaluated as good (), and the case where partial detachment was observed or the adhesive tape was detached was evaluated as poor (x).

(66) The same evaluations were conducted using a 2.38% TMAH aqueous solution as a base and acetone as an organic solvent.

(67) Table 4 shows the results.

(68) (3-2)

(69) The laminate including the crosslinked and cured adhesive component was evaluated for heat resistance by the following method.

(70) Specifically, the laminate including the crosslinked and cured adhesive component was subjected to thermal treatment at 200 C. for one hour. The thermally treated laminate was taken out and the temperature thereof was cooled to 25 C., and the bonded surface between the adhesive tape and the silicon wafer was visually observed from the quartz glass plate side. The case where no partial detachment was observed on the whole surface was evaluated as good (), and the case where partial detachment was observed or the adhesive tape was detached was evaluated as poor (x).

(71) The same evaluation was conducted using a 700-m-thick silicon wafer (circuit wafer) having a circuit with an about 5 m level difference.

(72) Table 4 shows the results.

(4) Evaluation of Adhesive Residue after High-Temperature Treatment

(73) The resulting adhesive tape was cut into a 20-cm-diameter circle and was adhered to a silicon wafer having a diameter of 20 cm and a thickness of about 750 m under vacuum. The other side of the adhesive tape (the side without the silicon wafer) was adhered to a quartz glass plate having a diameter of 20 cm and a thickness of 1 mm under vacuum, whereby a laminate was formed.

(74) The wafer side of the resulting laminate was subjected to grind grinding and polishing until the wafer had a 50 m thickness.

(75) Subsequently, the adhesive component of the laminate was crosslinked and cured by a thermal treatment at 100 C. for one hour.

(76) The laminate including the crosslinked and cured adhesive component was subjected to a thermal treatment at 200 C. for two hours. A dicing tape was adhered to the thermally treated silicon wafer on the side without the adhesive tape, and the wafer was fixed by suction. Then, the quartz glass plate and the adhesive tape were detached from the wafer.

(77) The adhesive tape-detached surface of the silicon wafer was visually observed. The case where no adhesive was left was evaluated as excellent (), the case where the area having adhesive residue was less than 5% of the whole area was evaluated as good (), and the case where the area having adhesive residue was 5% or more of the whole area was evaluated as poor (x).

(78) Also, the adhesive tape-detached surface of the silicon wafer was observed with an optical microscope at a magnification of 100 times. The case where no adhesive was left in the field of view was evaluated as excellent (), the case where the area having adhesive residue was less than 5% of the whole field of view was evaluated as good (), and the case where the area having adhesive residue was 5% or more of the whole field of view was evaluated as poor (x).

(79) Table 4 shows the results.

Examples 47 to 70, Comparative Example 3

(80) An adhesive composition and an adhesive tape were obtained in the same manner as in Example 46, except that the kind of the resin was as shown in Table 4 and that, in the preparation of the adhesive composition, a (meth)acrylic group-containing silicone compound (EBECRYL 350 (acrylic equivalent: 2) or EBECRYL 1360 (acrylic equivalent: 6), available from DAICEL-ALLNEX LTD.) and a plasticizer (UN-2600, UN-5500, or UN-7700, available from Negami Chemical Industrial Co., Ltd.) were further added according to Table 4. The resulting adhesive tape was evaluated in the same manner as in Example 46, except that the adhesive component was crosslinked and cured under the conditions shown in Table 4.

(81) In Comparative Example 3, the adhesive component was not crosslinked or cured by heating in the evaluation for chemical resistance, heat resistance, and adhesive residue.

(82) Table 4 shows the results.

(83) TABLE-US-00004 TABLE 4 Thermal polymerization Modulus of initiator Silicone compound Plasticizer elasticity Amount Amount Amount after (parts by Trade (parts by Trade (parts by Crosslinking and heating Resin weight) name weight) name weight) curing by heating (10.sup.5 Pa) Example 46 Resin A 1 100 C. 1 hr. 18 Example 47 Resin A 1 70 C. 1 hr. 33 Example 48 Resin A 1 .sup.150 C. 30 min. 27 Example 49 Resin A 1 EBECRYL350 0.5 100 C. 1 hr. 24 Example 50 Resin A 1 EBECRYL350 10 100 C. 1 hr. 30 Example 51 Resin A 1 EBECRYL350 30 100 C. 1 hr. 41 Example 52 Resin A 1 EBECRYL1360 15 100 C. 1 hr. 35 Example 53 Resin A 1 UN5500 5 100 C. 1 hr. 37 Example 54 Resin A 1 UN5500 20 100 C. 1 hr. 38 Example 55 Resin A 1 UN5500 50 100 C. 1 hr. 34 Example 56 Resin A 1 UN2600 20 100 C. 1 hr. 31 Example 57 Resin A 1 UN7700 20 100 C. 1 hr. 32 Example 58 Resin A 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 33 Example 59 Resin A 0.2 EBECRYL350 5 UN5500 20 100 C. 1 hr. 21 Example 60 Resin B 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 20 Example 61 Resin C 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 35 Example 62 Resin D 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 44 Example 63 Resin E 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 71 Example 64 Resin F 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 110 Example 65 Resin G 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 40 Example 66 Resin H 1 EBECRYL350 10 UN5500 20 100 C. 1 hr. 44 Example 67 Resin I 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 16 Example 68 Resin J 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 40 Example 69 Resin K 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 18 Example 70 Resin L 1 EBECRYL350 5 UN5500 20 100 C. 1 hr. 15 Comparative Resin A 1 N/A 0.7 Example 3 Adhesive residue Adhesive residue Heat resistance evaluation (visual evaluation Chemical resistance evaluation evaluation observation) (microscope) Organic Bare Circuit Bare Circuit Bare Circuit Acid Base solvent wafer wafer wafer wafer wafer wafer Example 46 Example 47 Example 48 Example 49 Example 50 Example 51 Example 52 Example 53 Example 54 Example 55 Example 56 Example 57 Example 58 Example 59 Example 60 Example 61 Example 62 Example 63 Example 64 Example 65 Example 66 Example 67 Example 68 Example 69 Example 70 Comparative X X X X X X X X Example 3

Example 71

(1) Production of Adhesive Tape

(84) For 100 parts by weight of the resin solids content of the ethyl acetate solution of the resin A, 1 part by weight of a thermal polymerization initiator (Perhexyl O, available from NOF Corporation), 5 parts by weight of a silicone compound (EBECRYL 350, available from DAICEL-ALLNEX LTD.), 20 parts by weight of a plasticizer (UN-5500, available from Negami Chemical Industrial Co., Ltd.), and 10 parts by weight of 5-phenyl-1H-tetrazole as a gas generating agent were mixed with the ethyl acetate solution of the resin A.

(85) The resulting ethyl acetate solution of the adhesive composition was applied with a doctor blade to a 50-m-thick transparent polyethylene naphthalate film having a corona treated surface (to the corona treated surface) such that the resulting dry coating film would have a 30 m thickness. The applied solution was heated and dried at 80 C. for five minutes. The film was then left to stand and cured at 40 C. for three days. Thus, an adhesive tape was obtained.

(2) Evaluation of the Modulus of Elasticity of the Adhesive Composition Crosslinked and Cured by Heating

(86) A sample for evaluation was prepared as follows. The ethyl acetate solution of the adhesive composition was applied with a doctor blade to a 50-m-thick transparent polyethylene naphthalate film having a corona treated surface (to the corona treated surface) such that the resulting dry coating film would have a 500 m thickness. The applied solution was heated and dried at 110 C. for five minutes. The resulting film was left to stand and cured at 40 C. for three days. The resulting adhesive tape was cut into a rectangle having a length of 0.6 cm and a width of 1.0 cm. This rectangular piece was used as a sample for evaluation. Then, the adhesive component of the sample was crosslinked and cured by a thermal treatment at 100 C. for one hour. The storage modulus at 25 C. of the cured sample for evaluation, as measured by dynamic viscoelasticity measurement under shear mode and continuous temperature rise from 50 C. to 300 C. at an angular frequency of 10 Hz, was determined.

(3) Evaluation for Chemical Resistance and Heat Resistance after Heating

(87) The resulting adhesive tape was cut into a 20-cm-diameter circle and adhered to a silicon wafer having a diameter of 20 cm and a thickness of about 750 m under vacuum. The other side of the adhesive tape (the side without the silicon wafer) was adhered to a quartz glass plate having a diameter of 20 cm and a thickness of 1 mm under vacuum, whereby a laminate was formed.

(88) The wafer side of the resulting laminate was subjected to grind grinding and polishing until the wafer had a 50 m thickness.

(89) Subsequently, the adhesive component of the laminate was crosslinked and cured by a thermal treatment at 100 C. for one hour.

(90) (3-1)

(91) The laminate including the crosslinked and cured adhesive component was evaluated for the chemical resistance to an acid, base, and organic solvent by the following method.

(92) Specifically, a Standard Clean 1 (SC1) solution was prepared as an acid, and the laminate including the crosslinked and cured adhesive component was immersed in the SC 1 solution at 60 C. for one hour. The laminate was taken out after the immersion, and the bonded surface between the adhesive tape and the silicon wafer was visually observed from the quartz glass plate side. The case where no partial detachment was observed on the whole surface was evaluated as good (), and the case where partial detachment was observed or the adhesive tape was detached was evaluated as poor (x).

(93) The same evaluations were conducted using a 2.38% TMAH aqueous solution as a base and acetone as an organic solvent.

(94) Table 5 shows the results.

(95) (3-2)

(96) The laminate including the crosslinked and cured adhesive component was evaluated for the heat resistance by the following method.

(97) Specifically, the laminate including the crosslinked and cured adhesive component was subjected to thermal treatment at 200 C. for one hour. The thermally treated laminate was taken out and the temperature thereof was cooled to 25 C. The bonded surface between the adhesive tape and the silicon wafer was then visually observed from the quartz glass plate side. The case where no partial detachment was observed on the whole surface was evaluated as good (), and the case where partial detachment was observed or the adhesive tape was detached was evaluated as poor (x).

(98) Table 5 shows the results.

(4) Evaluation of Adhesive Residue after High-Temperature Treatment

(99) The resulting adhesive tape was cut into a 20-cm-diameter circle and adhered to a silicon wafer having a diameter of 20 cm and a thickness of about 750 m under vacuum. The other side of the adhesive tape (the side without the silicon wafer) was adhered to a quartz glass plate having a diameter of 20 cm and a thickness of 1 mm under vacuum, whereby a laminate was formed.

(100) The wafer side of the resulting laminate was subjected to grind grinding and polishing until the wafer had a 50 m thickness.

(101) Subsequently, the adhesive component of the laminate was crosslinked and cured by a thermal treatment at 100 C. for one hour.

(102) The laminate including the crosslinked and cured adhesive component was subjected to a thermal treatment at 200 C. for two hours. A dicing tape was adhered to the thermally treated silicon wafer on the side without the adhesive tape, and the wafer was fixed by suction. Then, the wafer was irradiated with light having an illuminance of 254 nm and an intensity of 70 mW/cm.sup.2 for 150 seconds from the Tempax glass side using an ultrahigh pressure mercury lamp. Then, the quartz glass plate and the adhesive tape were detached from the wafer.

(103) The surface of the adhesive tape-detached surface of the silicon wafer was visually observed. The case where no adhesive was left was evaluated as excellent (), the case where the area having adhesive residue was less than 5% of the whole area was evaluated as good (), and the case where the area having adhesive residue was 5% or more of the whole area was evaluated as poor (x).

(104) Also, the surface of the adhesive tape-detached surface of the silicon wafer was observed with an optical microscope at a magnification of 100 times. The case where no adhesive was left in the field of view was evaluated as excellent (), the case where the area having adhesive residue was less than 5% of the whole field of view was evaluated as good (), and the case where the area having adhesive residue was 5% or more of the whole field of view was evaluated as poor (x).

(105) Table 5 shows the results.

Examples 72 to 90, Comparative Example 4

(106) An adhesive composition and an adhesive tape were obtained in the same manner as in Example 71, except that the kind of the resin and the kind and the amount of the gas generating agents to be blended with the adhesive composition were as shown in Table 5. The resulting adhesive tape was evaluated in the same manner as in Example 71.

(107) In Comparative Example 4, the adhesive component was not crosslinked or cured by heating in the evaluation for chemical resistance, heat resistance, and adhesive residue.

(108) TABLE-US-00005 TABLE 5 Thermal polymerization Silicone Modulus of initiator compound Plasticizer Gas generating agent elasticity Amount Amount Amount Amount Crosslinking and after (parts by (parts by (parts by Compound (parts by curing by heating Resin weight) weight) weight) name weight) heating (10.sup.5 Pa) Example 71 Resin A 1 5 20 5-Phenyl-1H-tetrazole 10 100 C. 1 hr. 37 Example 72 Resin A 1 5 20 4,5 Ditetrazolyl- 10 100 C. 1 hr. 38 [1,2,3]triazole Example 73 Resin A 1 5 20 1-(p-Ethoxyphenyl)-5- 10 100 C. 1 hr. 34 mercaptotetrazole Example 74 Resin A 1 5 20 1-(4-Benzamide)-5- 10 100 C. 1 hr. 35 mercaptotetrazole Example 75 Resin A 1 5 20 5-Tolyltetrazole 10 100 C. 1 hr. 38 Example 76 Resin A 1 5 20 2-(5-Tetrazoyl)aniline 10 100 C. 1 hr. 36 Example 77 Resin A 1 5 20 5-(m- 10 100 C. 1 hr. 38 Aminophenyl)tetrazole Example 78 Resin A 1 5 20 5-Acetamide tetrazole 10 100 C. 1 hr. 39 Example 79 Resin A 1 5 20 N-(1H tetrazol-5-yl)-n- 10 100 C. 1 hr. 40 octane amide Example 80 Resin A 1 5 20 1-Cyclohexyl-5- 10 100 C. 1 hr. 35 chlorobutyl tetrazole Example 81 Resin A 1 5 20 Bistetrazole piperazine salt 10 100 C. 1 hr. 36 Example 82 Resin A 1 5 20 Bistetrazole diammonium 10 100 C. 1 hr. 35 salt Example 83 Resin A 1 5 20 Bistetrazole disodium salt 10 100 C. 1 hr. 39 Example 84 Resin A 1 5 20 Bistetrazole monohydrate 10 100 C. 1 hr. 34 Example 85 Resin A 1 5 20 Bistetrazole 10 100 C. 1 hr. 36 monoammonium Example 86 Resin A 1 5 20 5-Aminotetrazole 10 100 C. 1 hr. 34 monohydrate Example 87 Resin A 1 5 20 1-Methyl-5- 10 100 C. 1 hr. 34 mercaptotetrazole Example 88 Resin A 1 5 20 Bistetrazole disodium salt 50 100 C. 1 hr. 35 Example 89 Resin C 1 5 20 Bistetrazole disodium salt 10 100 C. 1 hr. 33 Example 90 Resin H 1 5 20 Bistetrazole disodium salt 10 100 C. 1 hr. 36 Comparative Resin A 1 5 20 5-Phenyl-1H-tetrazole 10 N/A 0.5 Example 4 Adhesive residue Adhesive residue Heat resistance evaluation (visual evaluation Chemical resistance evaluation evaluation observation) (microscope) Organic Bare Circuit Bare Circuit Bare Circuit Acid Base solvent wafer wafer wafer wafer wafer wafer Example 71 Example 72 Example 73 Example 74 Example 75 Example 76 Example 77 Example 78 Example 79 Example 80 Example 81 Example 82 Example 83 Example 84 Example 85 Example 86 Example 87 Example 88 Example 89 Example 90 Comparative X X X X X X X X X Example 4

Examples 91 to 93, Comparative Example 5

(109) An adhesive composition and an adhesive tape were obtained in the same manner as in Example 1, except that the kind of resin was as shown in Table 6, and, in the preparation of the adhesive composition, a fumed silica dispersed solution (REOLOSIL MT-10, available from Tokuyama Corporation), in which fumed silica was dispersed in methyl ethyl ketone with a homogenizer and the average particle size of the silica was adjusted to be 0.1 m; a (meth)acrylic group-containing silicone compound (EBECRYL 350 (acrylic equivalent: 2), available from DAICEL-ALLNEX LTD.); and a plasticizer (UN-5500, available from Negami Chemical Industrial Co., Ltd.) were added according to Table 6. The resulting adhesive tape was evaluated in the same manner as in Example 1.

(110) In Comparative Example 5, the adhesive component was not crosslinked or cured by ultraviolet light irradiation in the evaluation for chemical resistance, heat resistance, and adhesive residue.

(111) Table 6 shows the results.

(112) TABLE-US-00006 TABLE 6 Photopolymerization Fumed silica (MT10) initiator Silicone compound Plasticizer Average Amount Amount Amount Amount Ultraviolet Trade particle size (parts by (parts by Trade (parts by Trade (parts by light Resin name (m) weight) weight) name weight) name weight) irradiation Example 91 Resin A MT10 0.1 5 1 EBECRYL 5 UN 20 Irradiated 350 5500 Example 92 Resin A MT10 0.1 10 1 EBECRYL 5 UN 20 Irradiated 350 5500 Example 93 Resin A MT10 0.1 15 1 EBECRYL 5 UN 20 Irradiated 350 5500 Comparative Resin A MT10 0.1 5 1 EBECRYL 5 UN 20 Not Example 5 350 5500 irradiated Modulus of Adhesive residue Adhesive residue elasticity after Chemical resistance Heat resistance evaluation (visual evaluation ultraviolet light evaluation evaluation observation) (microscope) irradiation Organic Bare Circuit Bare Circuit Bare Circuit (10.sup.5 Pa) Acid Base solvent wafer wafer wafer wafer wafer wafer Example 91 51 Example 92 53 Example 93 55 Comparative 0.9 X X X X X X X X Example 5

INDUSTRIAL APPLICABILITY

(113) The present invention provides a method of treating a wafer in the state where the wafer is fixed on a support plate via an adhesive composition. Although the wafer is treated by a chemical, heating, or exothermic treatment, the method of treating a wafer achieves sufficient adhesiveness during the step of treating a surface of the wafer and allows detachment of the support plate from the wafer without damaging the wafer or leaving the adhesive on the wafer after the wafer treating step.