JP2003249471A - Protection sheet for semiconductor wafer processing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protection sheet for semiconductor wafer processing which has basic performance as a semiconductor wafer processing protection sheet such as a back grind sheet and further has heat resistance which resists heating process, and also can restrain warp of a wafer in cooling after heating process. <P>SOLUTION: In a protection sheet for semiconductor wafer processing wherein an adhesive layer is laminated on a base material sheet, a base material sheet has at least one layer of a porous base material sheet. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a protective sheet for semiconductor wafer processing. The protective sheet for processing a semiconductor wafer according to the present invention cuts a protective sheet used for protecting a wafer and semiconductor components such as a wafer and a semiconductor package into individual sizes in a wafer grinding process in various semiconductor manufacturing processes ( It is useful as a protective sheet used for fixing these during dicing).

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor wafer, the back surface of a patterned wafer is generally subjected to a back grinding step of grinding the wafer to a predetermined thickness with a grinding machine such as a back grinder. that time,
For the purpose of protecting the wafer, a back grind sheet is attached to the front surface of the wafer, and back surface grinding is generally performed. Further, a die attach film is used as a protective sheet when mounting a chip obtained by dividing a wafer on a substrate or another chip. Recently, many methods have been adopted in which a die attach film is attached to the back surface of the wafer before the wafer is divided, and then the wafer is divided into chips by dicing. As such a semiconductor wafer protective sheet, an adhesive sheet in which an adhesive layer is laminated on a base material sheet is used.

In recent years, wafers such as 8-inch and 12-inch wafers have become larger, and wafers have become thinner for IC card applications and the like. As wafers are becoming thinner, the processing system itself after the backside grinding of the wafer is changing. For example, conventionally, the back grind sheet, which has protected the wafer surface during the back surface grinding of the wafer, is usually peeled off immediately after the back surface grinding, and then the die attach film is usually attached. However, the thinning of the wafer has made it difficult to handle the back-ground wafer. Therefore, even when the die attach film is attached in consideration of damage to the wafer, a method of attaching the die attach film while protecting the wafer surface with the back grind sheet and then peeling the back grind sheet is spreading.

After the die attach film is stuck in the above-mentioned method, a heating step of pre-curing the die attach film at a high temperature of about 120 ° C. to 200 ° C. is usually performed. However, the heat resistance of the conventionally known back grind sheet is insufficient. Further, when the wafer is cooled to room temperature after the heating step, there is a problem that the wafer largely warps due to the difference in linear expansion coefficient between the wafer and the back grind sheet.

[0005]

DISCLOSURE OF THE INVENTION The present invention has basic performance as a protective sheet for processing a semiconductor wafer such as a back grind sheet and the like, and has heat resistance capable of withstanding a heating process, and at the time of cooling after the heating process. It is an object of the present invention to provide a protective sheet for processing a semiconductor wafer in which the warp of the wafer can be suppressed. Another object of the present invention is to provide a method for manufacturing a semiconductor wafer using the protective sheet for processing a semiconductor wafer, and further a semiconductor element obtained by the manufacturing method.

[0006]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned object can be achieved by the protective sheet for processing a semiconductor wafer described below, and have completed the present invention. Came to do.

That is, according to the present invention, in a protective sheet for processing a semiconductor wafer in which an adhesive layer is laminated on a base material sheet, the base material sheet has at least one layer of a porous base material sheet. A protective sheet for wafer processing.

The protective sheet for semiconductor wafer processing of the present invention uses a porous base material sheet as the base material sheet, and has heat resistance capable of withstanding the heating step. Further, the semiconductor wafer processing protective sheet of the present invention has basic performance such as a back grinding sheet, and can suppress the warp of a large wafer when it is thinned by a back grinding process,
Even when the wafer is cooled to room temperature after the heating process, the warp of the wafer can be suppressed. Therefore, even a thinned wafer can be efficiently transported in each process.

In the semiconductor wafer processing protective sheet, it is preferable that a soft resin layer is provided between the base sheet and the pressure-sensitive adhesive layer. Warping of the wafer can be further suppressed by the soft resin layer.

The present invention also includes a method of manufacturing a semiconductor wafer, which comprises a step of protecting and processing a semiconductor wafer using the semiconductor wafer processing protection sheet.
Regarding When the processing step is a back grinding step, the protective sheet for processing a semiconductor wafer of the present invention is preferably used. In particular, during or after the processing step, 80
It is preferably used when it has a heating step at a temperature of ℃ or higher.

Further, the present invention relates to a semiconductor device manufactured by the above manufacturing method. According to the manufacturing method of the present invention, it is possible to obtain a semiconductor element in which the wafer is not warped or is suppressed to be small.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The semiconductor wafer processing protective sheet of the present invention will be described in detail below with reference to FIG. Figure 1
As shown in FIG. 1, the protective sheet for processing a semiconductor wafer of the present invention comprises a base sheet 1 made of a porous base sheet 1a,
The adhesive layer 2 is provided. Moreover, the separator 3 is provided on the pressure-sensitive adhesive layer 2 as needed. In FIG. 1, the pressure-sensitive adhesive layer 2 is provided on one side of the base sheet 1, but the base sheet 1
It is also possible to form the pressure-sensitive adhesive layer 2 on both surfaces of. The protective sheet for semiconductor wafer processing may be rolled into a tape shape.

FIG. 1 illustrates the case where the base sheet 1 has one layer of the porous base sheet 1a, but the base sheet 1 has at least the porous base sheet 1a. The porous substrate sheet 1a may have a single-layer structure or a multi-layer structure. Also, the base sheet 1
May have a multi-layer structure of a porous base material sheet 1a and another base material sheet 1b as shown in FIGS. Further, as shown in FIG. 4, a soft resin layer 4 can be provided between the base material sheet 1 and the pressure-sensitive adhesive layer 2.

Various polymers can be used as a material for forming the porous substrate sheet. For example, polyimide, polyamide, polyamideimide, polyetherimide, polysulfone, polyethersulfone, polyetherketone or a derivative obtained by introducing a sulfonic acid group, a carboxyl group, a quaternary amino group or the like into these is preferably used. These polymers may be used alone or as a mixture. Of these polymers, when high heat resistance is required, heat resistant resins such as polyimide and polyamide are preferably used.

The method for producing the porous substrate sheet is not particularly limited, and includes wet coagulation method, dry coagulation method, stretching method, supercritical extraction method,
Various film forming methods such as a phase inversion method, a melting method and a sintering method can be adopted. Among these, the wet coagulation method is preferably used to obtain a thin porous substrate sheet. In the wet coagulation method, generally, a film-forming stock solution (dope) in which a polymer and additives are dissolved in a solvent is prepared and applied (cast) to a constant thickness on a supporting base material such as a glass plate. Porous by soaking in water to coagulate, or leaving in water vapor atmosphere to coagulate, then soaking in water to coagulate (gelate) the polymer, and then dry and remove coagulation liquid etc. Get a quality membrane. As the supporting base material, an inorganic material such as a stainless steel plate or a polymer film such as a polyethylene sheet can be used in addition to the glass plate.

The solvent for dissolving the polymer is not particularly limited as long as it dissolves the polymer and is soluble in the coagulating solvent. For example, an aprotic polar solvent can be preferably used in view of the solubility of the polymer and the speed of solvent substitution with the coagulating solvent. As the aprotic polar solvent, N-methyl-2-pyrrolidone, N, N-dimethylacetamide,
N, N-dimethylformamide, dimethyl sulfoxide, etc. can be illustrated. N-methyl-2-pyrrolidone is preferred as the aprotic polar solvent. Further, as the aprotic polar solvent, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, 1,2-dimethoxyethane,
A solvent such as 1,2-diethoxyethane or 1,2-dibutoxyethane may be mixed to adjust the rate of solvent substitution.

The dope is preferably -20 to 80 ° C.
It is applied in the temperature range of. Further, the coagulation solvent is not limited as long as it does not dissolve the resin used and is compatible with the above solvent, but for example, water, methanol, ethanol, alcohols such as isopropyl alcohol, and mixed solutions thereof are used. Especially, water is preferably used. The temperature of the coagulating solvent at the time of immersion is not particularly limited, but it is preferably 0 to 80 ° C.

The polymer concentration of the dope is preferably in the range of 5 to 25% by weight, more preferably 7 to 20% by weight. This is because if the concentration is too high, the viscosity becomes too high and handling becomes difficult, and if the concentration is too low, the porous film cannot be formed. An inorganic substance such as lithium nitrate or an organic substance such as polyvinylpyrrolidone can be added to the dope for controlling the shape and diameter of the pores. The concentration of the additive is preferably 1 to 10% by weight in the solution. When lithium nitrate is added, the rate of substitution between the solvent and the coagulating solvent is high, and a finger void structure (a structure having finger-like voids) can be formed in the sponge structure. By adding an additive such as polyvinylpyrrolidone that slows the coagulation speed, a porous substrate having a sponge structure uniformly spread can be obtained.

The pore size and porosity of the porous substrate sheet are not particularly limited, but an average pore size of 0.05 μm or more is preferable from the viewpoint of balance between stress relaxation and strength. More preferably 0.1
10 to 10 μm. Moreover, the porosity is 20 to 95%.
Is preferred. It is more preferably 30 to 80%.

The thickness of the porous substrate sheet is 1 to 200 μm
Is preferred. When the base material sheet is formed of the porous base material sheet alone, the thickness is more preferably 50 to 150 μm. When it is formed of a composite layer with another substrate sheet, the thickness is more preferably 30 to 150 μm.

As the other base material sheet, various materials used for the protective sheet for semiconductor wafer processing can be used without particular limitation. As the material, low density polyethylene, linear polyethylene, medium density polyethylene,
High density polyethylene, ultra low density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolyprolene, polybutene, polyolefin such as polymethylpentene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene- (meth) acrylic acid Copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer,
Ethylene-hexene copolymer, polyurethane, polyester such as polyethylene terephthalate, polyimide,
Examples thereof include polymers such as polyether ether ketone, polyvinyl chloride, polyvinylidene chloride, fluororesins, cellulosic resins, and crosslinked products thereof. These materials may be used by blending several kinds as necessary.

These other base sheets may be used without stretching, or may be subjected to uniaxial or biaxial stretching treatment as needed. If necessary, the surface thereof may be subjected to a conventional physical or chemical treatment such as a mat treatment, a corona discharge treatment, a primer treatment, a crosslinking treatment (chemical crosslinking (silane)). These other substrate sheets are used so that the total thickness with the porous substrate sheet is usually 400 μm or less, preferably about 250 μm.

As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer,
For example, a commonly used pressure sensitive adhesive can be used, and an appropriate adhesive such as an acrylic adhesive or a rubber adhesive can be used. Among them, acrylic adhesives having an acrylic polymer as a base polymer are preferable from the viewpoints of adhesiveness to a semiconductor wafer and cleanliness / cleanability of the semiconductor wafer after peeling with ultrapure water or an organic solvent such as alcohol.

Examples of the acrylic polymer include (meth) acrylic acid alkyl ester (for example, methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, Pentyl ester, isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester, tridecyl ester,
C1-C30 alkyl groups such as tetradecyl ester, hexadecyl ester, octadecyl ester, eicosyl ester, etc., especially straight-chain or branched alkyl ester having 4-18 carbon atoms) and (meth) acrylic acid Examples thereof include acrylic polymers using one or more cycloalkyl esters (eg, cyclopentyl ester, cyclohexyl ester) as a monomer component. In addition, (meth) acrylic acid ester means acrylic acid ester and / or methacrylic acid ester, and (meth) of the present invention has the same meaning.

The acrylic polymer is a unit corresponding to another monomer component copolymerizable with the (meth) acrylic acid alkyl ester or cycloalkyl ester, if necessary, for the purpose of modifying cohesive strength, heat resistance and the like. May be included. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; maleic anhydride. , Acid anhydride monomers such as itaconic anhydride; (meth)
2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate,
10-hydroxydecyl (meth) acrylate, (meth)
Hydroxyl group-containing monomers such as 12-hydroxylauryl acrylate and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate; styrenesulfonic acid, allylsulfonic acid, 2- (meth) acrylamide-
Sulfonic acid group-containing monomer such as 2-methylpropanesulfonic acid, (meth) acrylamidepropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalenesulfonic acid; Phosphoric acid group such as 2-hydroxyethylacryloyl phosphate Monomers: acrylamide, acrylonitrile and the like. These copolymerizable monomer components may be used alone or in combination of two or more. The amount of these copolymerizable monomers used is preferably 40% by weight or less based on the total monomer components.

Further, since the acrylic polymer is crosslinked, a polyfunctional monomer or the like can be contained as a monomer component for copolymerization, if necessary. Examples of such polyfunctional monomers include hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, Pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate
Acrylate, dipentaerythritol hexa (meth)
Examples thereof include acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, urethane (meth) acrylate and the like. These polyfunctional monomers may be used alone or in combination of two or more. The amount of the polyfunctional monomer used is preferably 30% by weight or less of the total monomer components from the viewpoint of adhesive properties and the like.

The acrylic polymer can be obtained by polymerizing a single monomer or a mixture of two or more kinds of monomers. The polymerization can be carried out by any method such as solution polymerization, emulsion polymerization, bulk polymerization and suspension polymerization. From the viewpoint of preventing contamination of semiconductor wafers and the like, the adhesive layer preferably has a low content of low molecular weight substances. From this point, the number average molecular weight of the acrylic polymer is preferably 300,000 or more, and more preferably about 400,000 to 3,000,000.

An external cross-linking agent may be appropriately used in the pressure-sensitive adhesive in order to increase the number average molecular weight of the acrylic polymer as the base polymer. As a specific means of the external crosslinking method, there is a method of adding a so-called crosslinking agent such as a polyisocyanate compound, an epoxy compound, an aziridine compound, a melamine-based crosslinking agent and reacting. When using an external crosslinking agent, the amount used is
It is appropriately determined depending on the balance with the base polymer to be crosslinked, and further according to the intended use as an adhesive.
Generally, it is preferable to add about 1 to 5 parts by weight to 100 parts by weight of the base polymer. further,
If necessary, in addition to the above-mentioned components, various conventionally known additives such as tackifiers and antioxidants may be used in the pressure-sensitive adhesive.

A radiation-curable pressure-sensitive adhesive can be used as the pressure-sensitive adhesive. As the radiation-curable pressure-sensitive adhesive, those having a radiation-curable functional group such as a carbon-carbon double bond and exhibiting adhesiveness can be used without particular limitation. The radiation-curable pressure-sensitive adhesive is preferably one whose adhesive force is lowered by irradiation with radiation (especially ultraviolet rays). According to such a pressure-sensitive adhesive layer, the protective sheet can be easily peeled off by irradiation of ultraviolet rays after the back grinding step.

Examples of radiation-curable pressure-sensitive adhesives include
An addition type radiation-curable pressure-sensitive adhesive obtained by blending a general pressure-sensitive adhesive with a radiation-curable monomer component or oligomer component can be exemplified. Examples of general pressure-sensitive adhesives include those similar to the pressure-sensitive pressure-sensitive adhesives such as the acrylic pressure-sensitive adhesives and the rubber-based pressure-sensitive adhesives.

Examples of the radiation-curable monomer component to be blended include urethane oligomer, urethane (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate.
Examples thereof include acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 1,4-butanediol di (meth) acrylate. The radiation-curable oligomer component includes various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers having a molecular weight of 100 to 100.
Those in the range of about 30,000 are suitable. The amount of the radiation-curable monomer component or oligomer component blended is such that the base polymer 10 such as an acrylic polymer that constitutes the adhesive is used.
It is, for example, 5 to 500 parts by weight, preferably 40 to 150 parts by weight, relative to 0 parts by weight.

As the radiation-curable pressure-sensitive adhesive, in addition to the addition-type radiation-curable pressure-sensitive adhesive described above, a carbon-carbon double bond may be used as a base polymer in the side chain of the polymer or in the main chain or in the main chain. There is an internal radiation curable pressure-sensitive adhesive having a terminal end. The internal radiation-curable pressure-sensitive adhesive does not need to contain a low-molecular weight component such as an oligomer component, or does not contain a large amount, so that the oligomer component does not move in the pressure-sensitive adhesive over time and is stable. It is preferable because the pressure-sensitive adhesive layer having the above layer structure can be formed.

As the base polymer having a carbon-carbon double bond, those having a carbon-carbon double bond and having tackiness can be used without particular limitation. As such a base polymer, one having an acrylic polymer as a basic skeleton is preferable. Examples of the basic skeleton of the acrylic polymer include the acrylic polymers exemplified above.

The method for introducing the carbon-carbon double bond into the acrylic polymer is not particularly limited and various methods can be adopted. However, the molecular design is to introduce the carbon-carbon double bond into the side chain of the polymer. It's easy. For example, after previously copolymerizing a monomer having a functional group with an acrylic polymer,
Examples thereof include a method of subjecting a compound having a functional group capable of reacting with this functional group and a carbon-carbon double bond to a condensation or addition reaction while maintaining the radiation-curability of the carbon-carbon double bond.

Examples of the combination of these functional groups include a carboxylic acid group and an epoxy group, a carboxylic acid group and an aziridyl group,
Examples thereof include a hydroxyl group and an isocyanate group.
Among these combinations of functional groups, the combination of a hydroxyl group and an isocyanate group is preferable because the reaction can be easily traced. In addition, the functional group may be on either side of the acrylic polymer and the compound, as long as the combination of these functional groups is a combination that produces the acrylic polymer having the carbon-carbon double bond. In the above preferable combination, it is preferable that the acrylic polymer has a hydroxyl group and the compound has an isocyanate group. In this case, as the isocyanate compound having a carbon-carbon double bond, for example, methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, m-isopropenyl-α, α
-Dimethylbenzyl isocyanate and the like.
As the acrylic polymer, those obtained by copolymerizing the above-exemplified hydroxy group-containing monomer, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, ether compound of diethylene glycol monovinyl ether, and the like are used.

The above-mentioned intrinsic type radiation curable pressure-sensitive adhesive can use the above-mentioned base polymer having a carbon-carbon double bond (particularly an acrylic polymer) alone, but the above radiation curable to the extent that the characteristics are not deteriorated. It is also possible to add a monomeric component or an oligomeric component having a volatile property. The radiation-curable oligomer component is usually the base polymer 100.
It is in the range of 30 parts by weight, preferably in the range of 0 to 10 parts by weight with respect to parts by weight.

The radiation-curable pressure-sensitive adhesive contains a photopolymerization initiator when it is cured by ultraviolet rays or the like.
Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl)
Α-Ketol compounds such as ketones, α-hydroxy-α, α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, 1-hydroxycyclohexylphenyl ketone; methoxyacetophenone,
2,2-dimethoxy-2-phenylacetophenone,
2,2-diethoxyacetophenone, 2-methyl-1-
Acetophenone compounds such as [4- (methylthio) -phenyl] -2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether and anisoin methyl ether; ketals such as benzyl dimethyl ketal Compounds; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2- (o-ethoxycarbonyl) oxime; benzophenone, benzoylbenzoic acid , 3,3′-Dimethyl-4-methoxybenzophenone and other benzophenone compounds; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxane Compounds such as benzene, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; acylphosphonates And so on. The blending amount of the photopolymerization initiator is, for example, 1 to 10 parts by weight, preferably 3 to 5 parts by weight, based on 100 parts by weight of the base polymer such as an acrylic polymer that constitutes the pressure-sensitive adhesive.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is usually 3 to 100 μm, preferably 10 to 30 μm.
The pressure-sensitive adhesive layer may be a single layer or a plurality of two or more layers.

The adhesive force used for forming the pressure-sensitive adhesive layer is appropriately determined according to the purpose of use, from the adhesion maintaining property for fixing and protecting the wafer and the peeling property from the wafer. For example, the adhesive layer has a 180 ° peel adhesive strength of 0.01 N / 2.
0mm-0.7N / 20mm, and further 0.01N / 2
It is desirable that the range is 0 mm to 0.5 N / 20 mm.

The soft resin layer can be provided as a layer that does not come into contact with the wafer in addition to the pressure-sensitive adhesive layer exemplified above. Examples of the material for forming the soft resin layer include ethylene-ethyl acrylate copolymer (EEA) and ethylene-
Examples thereof include acrylic acid copolymer (EAA) and ethylene-methyl methacrylate copolymer (EMMA). The thickness of the soft resin layer is not particularly limited, but 300 μ
m or less, preferably 40 to 200 μm.

The production of the protective sheet for processing a semiconductor wafer of the present invention can be carried out, for example, by directly forming the pressure-sensitive adhesive layer 2 on the base film 1, or after separately forming the pressure-sensitive adhesive layer 2 on the separator 3. Alternatively, a method of bonding them to the base film 1 can be adopted. When the soft resin layer 4 is also provided, the adhesive layer 2 is formed on the base film 1 after forming the soft resin layer 4.

The separator 3 is provided as needed. Examples of the constituent material of the separator 3 include paper, synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate. The surface of the separator 3 may be subjected to release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment, if necessary, in order to enhance the peelability from the pressure-sensitive adhesive layer 2. The thickness of the separator 3 is usually 10 to 200 μm, preferably 25 to 100 μm.
It is about m.

The protective sheet for processing a semiconductor wafer of the present invention is used according to a conventional method to protect and process a semiconductor wafer. Examples of the processing process include a thin processing process such as a back grinding process.

To attach the protective sheet to the pattern surface of the semiconductor wafer, the semiconductor wafer is placed on the table so that the pattern surface faces upward, and the adhesive layer of the protective sheet is superposed on the pattern surface, It is attached while being pressed by a pressing means such as a pressure roll. It is also possible to stack the semiconductor wafer and the protective sheet as described above in a pressurizable container (for example, an autoclave) and press the inside of the container to attach the semiconductor wafer to the wafer. At this time, it may be attached while being pressed by the pressing means. Further, it can be attached in the same manner as above in the vacuum chamber. The pasting method is not limited to these, and heating can be performed at the time of pasting. For thin processing, a conventional method can be adopted. Examples of thin processing machines include grinding machines and CMP pads. Thin processing is performed until the semiconductor wafer has a desired thickness.

After the thin processing, the protective sheet is peeled off.
As the pressure-sensitive adhesive layer of the protective sheet, when a radiation-curable pressure-sensitive adhesive whose adhesive strength is reduced by irradiation with radiation is used,
The protective sheet is irradiated with radiation to reduce the adhesive strength and then peeled off. The means of irradiation is not particularly limited,
For example, it is performed by ultraviolet irradiation.

When the protective sheet is peeled off after the die attach film is attached, a heating step of precuring the die attach film is performed. The protective sheet of the present invention has good heat resistance even under a high temperature heating environment,
Even when pre-cured at about 120 ° C to 200 ° C, the wafer is unlikely to warp.

[0047]

EXAMPLES Examples and the like specifically showing the constitution and effects of the present invention will be described below. The average pore diameter and porosity of the porous base material sheet were measured as follows.

(1) Average Pore Size of Porous Substrate Sheet Regarding the porous substrate sheet, a scanning electron microscope (SE
Photographing was carried out using M), and the average pore size was determined from the image analysis of the photograph by a computer.

(2) Porosity of Porous Substrate Sheet Porosity (%) = {(weight / density) / volume} × 100 The volume and weight of the porous substrate sheet were measured to obtain the porous substrate. The porosity was calculated by the above equation using the density of the sheet material.

Example 1 Aromatic polyamide (Conex, Teijin Ltd.) was used as N.
-Dissolved in methyl-2-pyrrolidone (NMP), and further added polyvinylpyrrolidone (PVP) and water, 100 parts by weight of aromatic polyamide, 900 parts by weight of NMP, PV
A polymer solution containing 40 parts by weight of P and 40 parts by weight of water was obtained. This polymer solution was applied on a glass plate so that the thickness was 350 μm, and then immersed in a water bath at 60 ° C. to form a porous base material sheet. Then, it was stored in water for 24 hours to remove the solvent.

The obtained porous substrate sheet has a thickness of 70 μm.
It had a sponge structure in which m continuous holes were formed. The average pore diameter was 3 μm and the porosity was 46%. A 40 μm-thick pressure-sensitive adhesive layer formed of an acrylic pressure-sensitive adhesive is bonded to the 70 μm-thick porous substrate sheet thus prepared,
A protective sheet for semiconductor wafer processing was produced.

Example 2 The aromatic polyamide of Example 1 was dissolved in NMP to obtain a polymer solution containing 100 parts by weight of aromatic polyamide and 900 parts by weight of NMP. This polymer solution has a thickness of 19
After coating on a polypropylene film so as to have a thickness of 0 μm, it was immersed in a water bath at 60 ° C. to form a porous substrate sheet. Then, it was stored in water for 24 hours to remove the solvent.

The obtained porous substrate sheet has a thickness of 35 μm.
It had a sponge structure in which m continuous holes were formed. The average pore diameter was 2 μm and the porosity was 45%. The thickness of 80 μm was added to the 35 μm porous substrate sheet thus prepared.
After laminating the ethylene-ethyl acrylate copolymer (soft resin layer) of Example 1, a 40 μm-thick adhesive layer formed of the same acrylic adhesive as in Example 1 was laminated to form a protective sheet for semiconductor wafer processing. It was made.

Comparative Example 1 A protective sheet for semiconductor wafer processing was prepared by laminating a 40 μm thick adhesive layer formed of the same acrylic adhesive as in Example 1 on a 75 μm thick polyethylene terephthalate film.

The protective sheet for semiconductor wafer processing obtained in the above Examples and Comparative Examples was attached to an 8-inch silicon mirror wafer (thickness: 750 μm). Then DIS
After the wafer was ground by a CO back grinder DFG-840 until the thickness of the wafer became 100 μm, the amount of warp (mm) of the wafer was evaluated. After that, the wafer was left on a hot plate at 180 ° C. for 2 minutes and then left at room temperature for 2 minutes, and the amount of warp (mm) of the wafer after heating was measured. The results are shown in Table 1.

(Amount of Warp) A wafer with a semiconductor wafer processing protection sheet attached to a flat plate is placed with the protection sheet facing upward, and the height (mm) of the wafer edge most floating above the flat plate. Was measured.

[0057]

[Table 1]

[Brief description of drawings]

FIG. 1 is an example of a cross-sectional view of a semiconductor wafer processing protection sheet.

FIG. 2 is an example of a cross-sectional view of a semiconductor wafer processing protection sheet.

FIG. 3 is an example of a cross-sectional view of a semiconductor wafer processing protection sheet.

FIG. 4 is an example of a cross-sectional view of a semiconductor wafer processing protection sheet.

[Explanation of symbols]

1 Base sheet 1a Porous substrate sheet 2 Adhesive layer 3 separator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuyuki Kiuchi             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor Tomokazu Takahashi             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor Toshiyuki Kawashima             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor Shinji Tahara             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 4J004 AA01 AA05 AA10 AA17 AB06                       AB07 CA03 CA04 CA05 CA06                       CB04 CC03 CC07 CD02 CD08                       FA04 FA05                 4J040 CA001 DF001 DF041 DF051                       EB132 EF282 FA141 HB14                       JA09 JB07 JB08 KA13 LA06                       NA20 PA23 PA42

Claims (6)

[Claims] 1. A semiconductor wafer processing protective sheet having a pressure-sensitive adhesive layer laminated on a base sheet, wherein the base sheet has at least one layer of a porous base sheet. Protective sheet. 2. The protective sheet for semiconductor wafer processing according to claim 1, further comprising a soft resin layer between the base sheet and the adhesive layer. 3. A method of manufacturing a semiconductor wafer, comprising the step of protecting and processing a semiconductor wafer with the protective sheet for processing a semiconductor wafer according to claim 1. 4. The method of manufacturing a semiconductor wafer according to claim 3, wherein the processing step is a back grinding step. 5. A temperature of 80 ° C. during or after the processing step.
The method of manufacturing a semiconductor wafer according to claim 3, comprising the above heating step. 6. A semiconductor device manufactured by the manufacturing method according to claim 3.