JPH11224869A - Peeling method for adhesive film for surface protection at manufacturing of semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a peeling method, capable of easily peeling off an adhesive film without breaking a wafer at the time of peeling off the adhesive film for semiconductor wafer surface protection, after grinding a semiconductor wafer back surface. SOLUTION: In this method for sticking an adhesive film 1 for the semiconductor wafer surface protection composed by providing an adhesive material layer 1b on one surface of a base material film 1a provided with a thermal shrinking property to the surface of the semiconductor wafer 2, grinding the back surface of the wafer and then heating, shrinking and peeling the adhesive film 1, after the back surface of the semiconductor wafer 2 is ground, in the state of fixing the wafer 2 to a chuck table 3, the adhesive film 1 is shrunk and peeled off from the wafer surface, while supplying hot water 5 to a boundary 6 of the adhesive material layer 1b of the adhesive film 1 and the wafer surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface of a semiconductor wafer such as silicon, gallium-arsenide or the like on which an integrated circuit is incorporated (referred to as "wafer" in this specification).
The present invention relates to a method of grinding a back surface of a semiconductor wafer, in which an adhesive film is adhered to the other surface, and the other surface of the wafer (hereinafter, referred to as “wafer back surface”) is ground, and then the adhesive film is peeled off.

[0002]

2. Description of the Related Art Generally, a semiconductor integrated circuit (hereinafter, referred to as an IC) is prepared by slicing a high-purity silicon single crystal or the like into a semiconductor wafer, and incorporating the integrated circuit into the surface by etching or the like. Grind the back surface using a grinder to a wafer thickness of about 50 to 500 μm,
It is manufactured by a method of dicing into chips.

[0003] Among these steps, there is a step of grinding the back surface of the semiconductor wafer to reduce the thickness of the wafer to an arbitrary thickness after the circuit is assembled on the front surface of the semiconductor wafer. In this process, an adhesive film for protecting the wafer surface is applied to the surface of the semiconductor wafer through the adhesive layer for the purpose of protecting circuits formed on the surface of the semiconductor wafer, preventing damage to the wafer, and facilitating the grinding of the wafer. A method of grinding the back surface of a semiconductor wafer while attaching and protecting it is used. In this backside grinding step, water called grinding water is applied to the wafer and the grinding wheel in order to remove grinding heat generated when grinding the wafer backside and wash away generated silicon dust. When the adhesive film for protecting the semiconductor surface is no longer required after the backside grinding is completed, an adhesive tape having a strong adhesive force called a peeling tape is applied to the base film side of the semiconductor wafer surface protecting film in an apparatus called a peeling machine. And peeling off via the peeling tape.

However, when the tape is peeled from the wafer using the peeling machine as described above, the wafer may be damaged when the peeling tape is applied, or the peeling failure due to the poor bonding between the peeling tape and the surface protection adhesive film. Sometimes occurred. Further, the device for peeling off the pressure-sensitive adhesive film for surface protection using the above-described peeling tape has a complicated mechanism and is large-scale, which leads to an increase in equipment cost.

As a method for solving the above problem, for example, Japanese Patent Application Laid-Open No. Hei 8-222535 discloses that a surface tension is 35 dy.
An adhesive is applied to one side of a release film having a Necat / cm and a Vicat softening point of 100 ° C. or higher, dried and provided with an adhesive layer, and then the surface of the adhesive layer has a surface tension of 35 dy.
Ne / cm or more, an ethylene-vinyl acetate copolymer stretched film having a shrinkage ratio at 25 ° C of less than 5% and a shrinkage ratio of 5 to 50% when immersed in warm water of 50 to 80 ° C. Pressing, the adhesive film for protecting the semiconductor wafer surface obtained by transferring the pressure-sensitive adhesive layer to one surface of the stretched ethylene-vinyl acetate copolymer film is attached to the semiconductor wafer surface via the pressure-sensitive adhesive layer. Then, after grinding the back surface of the semiconductor wafer, the semiconductor wafer is immersed in warm water at 50 to 80 ° C., and the adhesive film for protecting the semiconductor wafer surface is peeled off from the semiconductor wafer surface. A method of use is disclosed. According to the present invention, when the adhesive film for protecting the surface of a semiconductor wafer is peeled from a semiconductor wafer having a thickness of 200 μm or less and a diameter of about 8 inches after grinding the back surface, the wafer is easily peeled without being damaged. It is stated that it can be.

Japanese Patent Application Laid-Open No. Hei 7-201787 discloses that one surface of a heat-shrinkable plastic film has (i)
A partially crosslinked product of a carboxyl group-containing hydrophilic polymer in which at least a part of carboxyl groups is partially neutralized, (i.
i) A wafer surface protection sheet provided with a pressure-sensitive adhesive layer containing at least one kind of a room temperature liquid surfactant selected from the group consisting of anionic surfactants is disclosed. It describes that the surface protection sheet can be peeled off.

However, even in the case of the above invention, the wafer may be damaged when the adhesive film is peeled off depending on the diameter of the wafer, the thickness after grinding the back surface, and the surface shape. The problem of this damage is that as the diameter of the semiconductor wafer becomes larger,
In addition, as the thickness after the back surface grinding becomes thinner, it tends to occur more easily. Also, even if the wafer has the same diameter and the same thickness after grinding the back surface, the scribing line (also referred to as “street”). Depending on the surface shape of the semiconductor wafer, such as the width and depth of the path through which the wafer passes, some wafers are easily damaged. The greater the unevenness of the wafer surface, such as the depth of the scribe line, the more the damage tends to occur.

In recent years, with the spread of portable mobile computers, portable telephones, cards with built-in ICs, and the like, semiconductor chips have become thinner.
The thickness was about 500 μm, but it was reduced to about 100 μm or less depending on the type of IC chip.
It is considered that the thickness can be reduced to about 0 μm. Also, the wafer diameter has been increased from 12 inches in the past to 12 inches in the future, and it is considered that the diameter will be further increased to 16 inches. Furthermore, several tens of μm
Semiconductor wafers with large irregularities have also appeared.

Accordingly, in grinding the back surface of the semiconductor wafer, the surface of the wafer is protected during the back surface grinding, and the wafer can be easily peeled at the time of peeling without damaging the wafer. It has been desired to develop a peeling method that can be used to perform a peeling operation.

[0010]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to minimize damage to a wafer and to break the wafer when peeling off the adhesive film for protecting the surface of the semiconductor wafer after grinding the back surface of the semiconductor wafer. An object of the present invention is to provide a method for peeling off a surface protecting pressure-sensitive adhesive film at the time of manufacturing a semiconductor wafer, which can easily peel off the pressure-sensitive adhesive film without any problem.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the backing of the wafer is ground using an adhesive film for protecting the surface of a semiconductor wafer whose base film has heat shrinkability. It has been found out that when the adhesive film is peeled off by heat shrinkage, the semiconductor wafer may be damaged for the following reasons. The heating causes the base film to shrink, and this stress is transmitted to the wafer via the adhesive layer. If the interfacial adhesion between the pressure-sensitive adhesive layer and the surface of the semiconductor wafer is smaller than the strength of the wafer, the pressure-sensitive adhesive film is peeled off before the wafer is broken due to shrinkage stress, so that the wafer is not damaged. However, as the diameter of the wafer becomes larger, the thickness of the wafer becomes thinner after grinding, and the surface of the wafer becomes more diversified, the strength of the wafer becomes lower. As a result, when the interfacial adhesive force between the pressure-sensitive adhesive layer and the semiconductor wafer surface becomes larger than the strength of the wafer, the wafer is damaged by the shrinkage stress of the base film. Therefore, in order to prevent breakage at the time of peeling, it is necessary to always make the interfacial adhesive force between the wafer surface and the pressure-sensitive adhesive layer smaller than the strength of the wafer.

The present inventors have found that the adhesive strength when a normal adhesive film is peeled off at a speed of about 300 mm / min in warm water at 50 to 80 ° C. is JIS-Z-0237.
Has been found to be significantly lower (in some cases less than half) than the adhesive strength measured by the method specified in (1). It is presumed that the cause of the decrease in the adhesive force is mainly due to the decrease in the interfacial adhesive force due to the hot water entering the peeling interface due to the capillary phenomenon.

When this phenomenon is attempted to use the heat-shrinkable adhesive film for grinding the back surface of the semiconductor wafer,
If the wafer after grinding is simply immersed in warm water with the adhesive film adhered, shrinkage of the base film occurs all at once, the shrinkage rate of the base film is high, and the infiltration of warm water by capillary action catches up. In some cases, a sufficient decrease in interfacial adhesion cannot be caused, and the wafer may be damaged.

On the other hand, if the wafer is fixed to a fixture such as a chuck table and hot water is positively supplied from the edge of the wafer to the interface between the wafer surface and the adhesive layer, the shrinkage of the base film is reduced. The present invention has found that the adhesive film can be generated relatively selectively, and that the capillary phenomenon can follow the shrinkage speed, the interfacial adhesion decreases, and the adhesive film can be peeled off without damaging the semiconductor wafer. Reached.

That is, according to the present invention, an adhesive film for protecting the surface of a semiconductor wafer in which an adhesive layer is provided on one side of a heat-shrinkable base film is attached to the surface of the semiconductor wafer, and the back surface of the wafer is ground. Then, in a method of heating, shrinking, and peeling the pressure-sensitive adhesive film, after grinding the back surface of the semiconductor wafer, supplying hot water to the interface between the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film and the wafer surface with the wafer fixed to a chuck table. A method for peeling a surface protecting pressure-sensitive adhesive film at the time of manufacturing a semiconductor wafer, wherein the pressure-sensitive adhesive film is shrunk while being peeled off from the wafer surface.

A feature of the present invention is that, when the heat-shrinkable adhesive film for protecting the surface of a semiconductor wafer is peeled off from the semiconductor wafer after the back surface grinding, the adhesive film is removed from the edge of the wafer while the wafer is fixed to a chuck table. By supplying hot water to the interface between the pressure-sensitive adhesive layer and the wafer, it is possible to promote the penetration of the pressure-sensitive adhesive film between the pressure-sensitive adhesive layer and the wafer by capillary action of hot water, and to peel off the pressure-sensitive adhesive film while reducing the pressure-sensitive adhesive strength of the pressure-sensitive adhesive film. In this case, the adhesive film can be easily peeled off without causing a crack or the like of the wafer when the adhesive film for protecting the semiconductor wafer surface is peeled off.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. First, the pressure-sensitive adhesive film for protecting a semiconductor wafer surface used in the present invention (in this specification, it may be simply referred to as “pressure-sensitive adhesive film”) will be described. Such an adhesive film is obtained by forming an adhesive layer on one side of a heat-shrinkable base film. In order to protect the pressure-sensitive adhesive layer from environmental contamination such as during storage and transportation, a release film usually called a separator is attached to the surface of the pressure-sensitive adhesive layer. The adhesive film used in the present invention is usually
An adhesive is applied to one side of a release film, dried to form an adhesive layer, and then the adhesive layer is transferred to one side of a heat-shrinkable substrate film.

The base film constituting the adhesive film is:
When heated at 50-80 ° C, uniaxial or biaxial (longitudinal,
A film having a shrinkage of 5 to 50% in the (transverse) direction is preferable, and the type of the material is not particularly limited. If specifically exemplified, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, polybutadiene copolymer,
Examples include resins such as polybutadiene, soft vinyl chloride resin, polyolefin, polyester, polyamide, and ionomer, and copolymer elastomers thereof, and films of diene, nitrile, acrylic, and the like. The base film may be a single layer or a laminate.

However, in consideration of prevention of damage to the semiconductor wafer during grinding of the back surface of the wafer, an elastic film formed by processing a resin having a Shore D-type hardness of 40 or less specified in ASTM-D-2240 into a film shape, for example, Ethylene-
Vinyl acetate copolymer (hereinafter referred to as EVA) film,
A polybutadiene film or the like is preferably used.

The thickness of the base film is determined by the shape and surface condition of the semiconductor wafer to be protected, the method of grinding the back surface of the wafer, the grinding conditions, or the cutting of the adhesive film for protecting the wafer surface.
It is appropriately determined according to the workability such as sticking, but is usually 10 to
It is 1000 μm, preferably 50 to 300 μm.

The method for producing the substrate film is not particularly limited, and may be a method produced by a known method such as an extrusion molding method and a calendar molding method. The molding temperature may be higher than the glass transition point or softening point of the raw resin and lower than the decomposition temperature. In order to impart heat shrinkage to the base film, it is preferable to stretch in at least one axial direction. The stretching ratio affects the releasability, workability, and the like when the pressure-sensitive adhesive film for protecting the semiconductor wafer surface is peeled off from the wafer surface after the grinding of the back surface of the wafer. If the stretching ratio is low, when the film is peeled off from the wafer surface by the method of the present invention, the base film may not be sufficiently shrunk, and the peelability, workability and the like may be reduced. Considering this point, the stretching ratio is 1.2 times or more, preferably 1.5 times or more. The stretching direction of the base film is to stretch in the machine direction or the transverse direction.
Either axial stretching or biaxial stretching in which the film is stretched in the machine direction and the transverse direction may be used. The upper limit of the stretching ratio is about 10 times in consideration of, for example, tear during stretching.

There are no particular restrictions on the stretching method either. A longitudinal uniaxial stretching method such as a roll rolling method, a roll stretching method, a vertical / horizontal sequential biaxial stretching method using a tenter machine, and a vertical / horizontal simultaneous biaxial stretching method using a tenter machine are used. For example, a known stretching method may be used. The stretching temperature is preferably from 40 to 70 ° C.
The base film stretched as described above is preferably subjected to a heat treatment so as not to cause shrinkage over time. In this case, the heat treatment temperature is preferably 45 to 80C.

Further, in order to increase the adhesive strength between the base film and the pressure-sensitive adhesive layer, the surface of the base film on which the pressure-sensitive adhesive layer is provided is preferably subjected to a corona discharge treatment, a chemical treatment or the like. An undercoat may be used between the base film and the pressure-sensitive adhesive layer.

The heat shrinkage of the base film was determined by selecting an arbitrary portion of the base film, heating a square sample of 10 cm in length and width in an air oven for 1 minute, and then standing at room temperature for 5 minutes. The length of the sample piece is measured, and the length is determined from the length before and after heating.

As the release film, polypropylene,
Synthetic resin films such as polyethylene terephthalate are exemplified. It is preferable that the surface (adhesive layer side) is subjected to easy peeling treatment such as silicone treatment as necessary.
The thickness of the release film is usually about 10 to 300 μm.

As the pressure-sensitive adhesive layer used for the pressure-sensitive adhesive film, any material can be used as long as it is designed according to the conditions such as the surface shape and diameter of the wafer to be ground, the type of surface protective film, and the amount of back surface grinding. Can, adhesive polymer,
It is formed by applying a coating liquid (solution or emulsion liquid) containing a crosslinking agent, an additive and the like to a base film or a release film.

The pressure-sensitive adhesive polymer is not particularly limited and can be appropriately selected from commercial products and the like. However, an acrylic pressure-sensitive adhesive is preferable from the viewpoints of tackiness, applicability, and non-staining property of the wafer surface. Such an acrylic pressure-sensitive adhesive is an acrylic acid alkyl ester monomer, and a carboxyl group,
It is obtained by copolymerizing a monomer mixture containing a monomer having a functional group such as a hydroxyl group. Further, a vinyl monomer, a polyfunctional monomer, an internal crosslinkable monomer, and the like copolymerizable therewith can be copolymerized as necessary. Also, if an emulsion-based adhesive polymer is used,
There is an effect that the wafer surface is cleaned in a heating peeling step using warm water, which will be described later.

Examples of the alkyl acrylate monomer include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, octyl acrylate, octyl methacrylate, and nonyl. Acrylate, nonyl methacrylate, dodecyl acrylate, dodecyl methacrylate and the like can be mentioned. The side chain alkyl group of these monomers may be linear or branched. Further, two or more of the above-mentioned alkyl acrylate monomers may be used in combination depending on the purpose.

Examples of the monomer having a functional group include monomers having a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and the like. Examples thereof include monomers having a hydroxyl group such as hydroxypropyl methacrylate, acrylamide, methacrylamide, dimethylaminoacrylate, dimethylaminomethacrylate, and the like, and other copolymerizable monomers such as vinyl acetate, styrene, and acrylonitrile.

The polymerization reaction mechanism of the pressure-sensitive adhesive polymer is as follows.
Radical polymerization, anionic polymerization, cationic polymerization and the like can be mentioned, but polymerization is preferably performed by radical polymerization in consideration of the production cost of the pressure-sensitive adhesive, the influence of the functional group of the monomer, the influence of ions on the surface of the semiconductor wafer, and the like. When polymerizing by a radical polymerization reaction, examples of a radical polymerization initiator include organic peroxides such as benzoyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, di-tert-butyl peroxide, and di-tert-amyl peroxide. Inorganic peroxides such as ammonium persulfate, potassium persulfate and sodium persulfate, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 4,4'-azobis And azo compounds such as -4-cyanovaleric acid.

When the polymerization is carried out by the emulsion polymerization method, among these radical polymerization initiators, inorganic peroxides such as water-soluble ammonium persulfate, potassium persulfate and sodium persulfate; An azo compound having a carboxyl group in the molecule, such as' -azobis-4-cyanovaleric acid, is preferred. In consideration of the influence of ions on the surface of the semiconductor wafer, an azo compound having a carboxyl group in the molecule, such as 4,4′-azobis-4-cyanovaleric acid, is more preferable.

The pressure-sensitive adhesive polymer obtained as described above is preferably crosslinked by a crosslinking agent having two or more functional groups in one molecule. This cross-linking agent is used to react with the functional group of the pressure-sensitive adhesive polymer to adjust the adhesion and cohesion. Examples of the crosslinking agent include epoxy compounds such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, and resorcin diglycidyl ether. , Tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylolpropane toluene diisocyanate 3 adduct,
Isocyanate compounds such as polyisocyanate, trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β-aziridinylpropionate, N, N′-diphenylmethane-
4,4′-bis (1-aziridinecarboxamide),
N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide), N, N'-toluene-2,4
-Bis-aziridinecarboxamide), aziridine compounds such as trimethylolpropane-tri-β- (2-methylaziridine) propionate, and melamine compounds such as hexamethoxymethylolmelamine.

These may be used alone or in combination of two or more. Among the above cross-linking agents, the epoxy-based cross-linking agent has a low speed of the cross-linking reaction, and when the reaction does not proceed sufficiently, the cohesive force of the pressure-sensitive adhesive layer is reduced, and the unevenness of the semiconductor wafer surface is caused by the pressure-sensitive adhesive layer. Contamination may occur. Therefore, as appropriate, a catalyst such as an amine is added, a monomer having an amine functional group having a catalytic action is copolymerized with the pressure-sensitive adhesive polymer, or an aziridine having an amine property when a crosslinking agent is used. It is preferable to use a system crosslinking agent in combination.

The amount of the cross-linking agent to be added is preferably within a range where the number of functional groups in the cross-linking agent does not exceed the number of functional groups in the pressure-sensitive adhesive polymer. However, when a new functional group is generated by the crosslinking reaction, or when the crosslinking reaction is slow, an excessive amount may be added as necessary. Normally, the adhesive strength of the surface protection adhesive film to be attached to the wafer surface when grinding the wafer back surface is determined by the grinding conditions of the wafer back surface, the diameter of the wafer,
It is set appropriately considering the thickness of the wafer after grinding, etc.
Usually, in accordance with the method specified in JIS-Z0237, the adhesive strength measured using a SUS-304BA plate as an adherend at a peeling speed of 300 mm / min and a peeling angle of 180 ° is 10 to 1000 g / 25 mm. And preferably about 30 to 600 g / 25 mm.

If necessary, the pressure-sensitive adhesive may contain an additive such as a surfactant so as not to contaminate the wafer surface. In particular, by containing a surfactant, there is an effect that the wafer surface is cleaned in a heat-peeling step using warm water described later. The surfactant may be nonionic or anionic as long as it does not contaminate the wafer surface. As a nonionic surfactant,
Examples thereof include polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, and polyoxyethylene lauryl ether. As anionic surfactants, alkyl diphenyl ether disulfonates and salts thereof, bisnaphthalene sulfonates and salts thereof, polyoxyalkyl sulfosuccinates and salts thereof, sulfates of polyoxyethylene alkyl phenyl ether and salts thereof, and the like Is mentioned.

The surfactants exemplified above may be used alone or in combination of two or more. The amount of the surfactant added is 0.1% based on the total weight of the pressure-sensitive adhesive polymer and the crosslinking agent, that is, 100 parts by weight of the crosslinked pressure-sensitive adhesive polymer.
It is preferably from 0.5 to 5 parts by weight. More preferably 0.05 to
3 parts by weight.

As a method of applying the pressure-sensitive adhesive coating solution to one surface of the base film or the release film, a conventionally known coating method, for example, a roll coater method, a gravure roll method, a bar coating method, or the like can be adopted. The drying condition of the applied pressure-sensitive adhesive is not particularly limited, but is generally 80 to 200 ° C.
It is preferable to dry in a temperature range of 10 seconds to 10 minutes. More preferably, at 80 to 170 ° C., 1
Drying for 5 seconds to 5 minutes. The thickness of the adhesive layer is
The surface condition of the semiconductor wafer, the shape, is appropriately determined by the grinding method of the back surface, etc., but in consideration of the adhesive force when grinding the back surface of the semiconductor wafer, the releasability after the grinding is completed, usually 2 to It is about 100 μm. Preferably 5
It is about 70 μm.

The pressure-sensitive adhesive film used in the present invention is obtained by coating a pressure-sensitive adhesive layer on a release film in consideration of the fact that a heat-shrinkable film is used as the base film and the contamination of the wafer surface is taken into consideration. It is preferable to transfer to a base film. After forming the pressure-sensitive adhesive layer on the surface of the release film as described above, the base film is laminated on the surface of the pressure-sensitive adhesive layer, and pressed to transfer the pressure-sensitive adhesive layer to the surface of the base film.

The transfer method may be a known method. For example, there is a method in which a base film is superimposed on the surface of the pressure-sensitive adhesive layer formed on the surface of the release film, and they are drawn through a nip roll and pressed. The release film is preferably peeled off from the surface of the pressure-sensitive adhesive layer immediately before being used as a pressure-sensitive adhesive film for protecting a semiconductor wafer surface.
The thus obtained pressure-sensitive adhesive film for protecting the surface of a semiconductor wafer is formed into a roll or cut into a predetermined shape, and then subjected to storage, transportation and the like.

From the viewpoint of preventing contamination of the semiconductor wafer surface,
The manufacturing environment for all raw materials such as base films, release films, adhesives, and the environment for applying and drying the adhesives must be maintained in a class 1,000 or less cleanliness specified by US Federal Standard 209b. preferable.

Next, the step of grinding the back surface of the semiconductor wafer and the method of peeling the pressure-sensitive adhesive film for surface protection according to the present invention after the step is described. Since a release film is usually attached to the pressure-sensitive adhesive film used in the present invention to protect the pressure-sensitive adhesive layer, first, the release film is peeled off to expose the pressure-sensitive adhesive layer. The adhesive film is adhered to the surface of the semiconductor wafer via the adhesive layer. Then, the semiconductor wafer is fixed to a chuck table or the like of a wafer backside grinding machine via the base film layer of the adhesive film for protecting the semiconductor wafer surface. Next, the back surface of the wafer is ground to a predetermined thickness by a grinding machine. It is common that cooling water is injected into a grinding surface during grinding. After the grinding is completed, grinding water is removed by, for example, pouring pure water into the grinding surface. Next, the wafer is fixed to the chuck table,
By supplying hot water from the wafer end surface to the interface between the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film and the wafer surface, the pressure-sensitive adhesive film for protecting the semiconductor wafer surface is peeled off from the wafer surface. After peeling off the adhesive film, the surface of the semiconductor wafer is subjected to a washing treatment such as washing with water, if necessary.

The adhesive film for protecting the semiconductor wafer surface is peeled off when the adhesive film becomes unnecessary after grinding the back surface of the semiconductor wafer. For semiconductor wafers after back grinding, those that undergo a chemical treatment step such as chemical etching performed for the purpose of removing distortion of the wafer, removing an oxide film, etc., peel the adhesive film according to the present invention after the completion of the step. You may. The back grinding method of the present invention is not particularly limited, and a known grinding method can be applied. For example, a through-feed system, an in-feed system, and the like can be given.

In the method of peeling the adhesive film, hot water is supplied from the wafer end surface to the adhesive layer and the wafer interface,
What is necessary is just to peel off sequentially. When peeling, the semiconductor wafer is fixed to a chuck table. Preferably, the entire back surface of the wafer is fixed to the chuck table in close contact. In this case, since the wafer is reinforced by the chuck table, the wafer is less likely to be damaged. Examples of the chuck table include a vacuum chuck table.

The above-mentioned peeling method according to the present invention will be described in more detail with reference to the accompanying drawings. For example, as shown in FIG. 1, an adhesive film (1a) and an adhesive layer (1b) comprising an adhesive layer (1b) Semiconductor wafer (2) to which 1) is attached
Is fixed with a chuck table (3) on the back surface thereof, and hot water (5) is supplied to the interface between the pressure-sensitive adhesive layer (1b) and the surface of the wafer (2) by the nozzle (4). As the pressure-sensitive adhesive film (1) shrinks and peels off, the pressure-sensitive adhesive film (1) is peeled off while supplying hot water (5) to the peeling interface (6) as shown in FIG.

The temperature of the supplied hot water depends on the base film (1).
There is no particular limitation as long as a) can be shrunk, but it is 50 to 50 depending on the stretching ratio of the base film (1a), the adhesive strength of the pressure-sensitive adhesive layer (1b), and the kind of the peeling method.
It is preferable to appropriately select the temperature in the range of 80 ° C. The supply amount of the hot water may be appropriately selected depending on the size of the semiconductor wafer, the thickness of the wafer after back grinding, the adhesive strength of the adhesive layer of the adhesive film, and the like.

It is preferable to use hot water that does not contaminate the semiconductor wafer surface. Further, by supplying warm water at the time of peeling the adhesive film, there is also an effect of cleaning the wafer surface at the same time. In this case, the cleaning step usually performed after the back surface grinding step can be omitted, and the process can be simplified in some cases. Further, by using an emulsion-based pressure-sensitive adhesive polymer as the pressure-sensitive adhesive polymer constituting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film, or by including a surfactant in the pressure-sensitive adhesive layer, the above-described cleaning effect can be further enhanced.

When peeling the pressure-sensitive adhesive film according to the present invention,
Depending on the method and amount of hot water supplied, the adhesive film may remain in the form of a roll on the wafer. In this case, as a method of removing the adhesive film from the wafer, a method of rotating the wafer and applying a centrifugal force to the roll-shaped adhesive film to remove the adhesive film from the wafer, or a method of turning the wafer surface downward, There is a method of dropping the film.

Further, since the adhesive film peeling method according to the present invention is as simple as described above, the peeling device for carrying out the method may have a very simple mechanism, so that the device is installed in a wafer back surface grinding machine. It is also possible to
By doing so, it is possible to prevent breakage when transferring the wafer to the peeling machine.

The time required for peeling the surface protective adhesive film from the semiconductor wafer is preferably about 1 to 60 seconds in consideration of workability and the like. Further, more preferably, it is about 1 to 30 seconds.

The present invention may be applied to a semiconductor wafer of any size and a wafer having a thickness after grinding the back surface, since stress applied to the semiconductor wafer during peeling and damage to the semiconductor wafer can be minimized. Is a large diameter of 8 to 12 inches, and the wafer thickness after back grinding is 300
It may be used for a wafer having a diameter of about μm or less, and is particularly preferably used for a wafer having a large diameter of 8 inches or more and having a thickness of about 200 μm or less after grinding the back surface. The size of the semiconductor wafer is expected to be further increased in the future, for example, to about 16 inches,
In such a case, the method of the present invention can be suitably used. Semiconductor wafers to which the present invention can be applied include silicon wafers, germanium, gallium-arsenic, and gallium-
Arsenic-aluminum and the like.

[0051]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to only these Examples. The various characteristic values shown in the examples were measured by the following methods.

(1) Shrinkage rate of adhesive film (%) An arbitrary portion of the adhesive film was selected, and the length and width thereof were 10% each.
Make a square cm piece. After peeling the release film from the sample piece, the film is heated in an air oven at a temperature of 70 ° C. for 1 minute, and then left at room temperature for 5 minutes. The length of the sample piece in the longitudinal direction (machine direction) is measured, and the shrinkage ratio is determined from the length before and after heating using the following equation. Shrinkage (%) = {(length of sample before heating−length of sample after heating) / length of sample before heating} × 100

(2) Measurement of Surface Contamination by ESCA The surface of the semiconductor wafer was measured by ESCA (X-ray photoelectron spectroscopy).
To determine the ratio of carbon to silicon (Si) (hereinafter referred to as C / Si ratio), and examined the state of contamination of the silicon wafer with organic substances. <ESCA measurement conditions and C / Si ratio> X-ray source: MgKα ray (1253.6 eV), X-ray output:
240 W, measured vacuum degree: 3 × 10 −7 Pa or less, C / S
i value: (Peak area of carbon) / (Peak area of silicon) Measuring device: ESCA-3200 (manufactured by Shimadzu Corporation) <Evaluation method of C / Si value> C / Si of silicon mirror wafer surface before sticking adhesive film The Si value is usually 0.1.
10 ± 0.01. The C / Si value of the surface of the silicon mirror wafer after the adhesive film was attached and peeled was 0.
The larger the value exceeds 10, the more the surface of the wafer is contaminated by the adhesive film. Usually, when the C / Si value is 0.15 or less, it is determined that the level is practically acceptable.

[Preparation Example] Production of pressure-sensitive adhesive film for semiconductor wafer surface protection In a polymerization reactor, 148 parts by weight of deionized water, ammonium salt of polyoxyethylene nonylphenyl ether sulfate as an anionic surfactant (Nippon Emulsifier Co., Ltd.)
Manufactured and trade name: Newcol-560SF, 50% by weight aqueous solution) 2 parts by weight (1 part by weight as a surfactant alone), 4,4′-azobis-4-cyanovaleric acid (Otsuka Chemical Co., Ltd.) as a polymerization initiator ), Product name: ACVA)
0.5 parts by weight, 74 parts by weight of butyl acrylate, 14 parts by weight of methyl methacrylate, 9 parts by weight of 2-hydroxyethyl methacrylate, 2 parts by weight of methacrylic acid and 1 part by weight of acrylamide are added, and the mixture is stirred at 70 ° C. For 9 hours to obtain an acrylic resin-based water emulsion. This was neutralized with 14% by weight of aqueous ammonia to obtain a pressure-sensitive adhesive polymer (base) emulsion having a solid content of about 40% by weight. 100 parts by weight of the obtained pressure-sensitive adhesive base material emulsion (pressure-sensitive adhesive polymer concentration: about 40% by weight) was collected, and 14
The pH was adjusted to 9.3 by adding aqueous ammonia by weight. Next, 1.7 parts by weight of an aziridine-based crosslinking agent and a film-forming aid were added to obtain a pressure-sensitive adhesive coating solution.

Thickness 50 μm formed by T-die extrusion
Using a polypropylene film as a release film,
The acrylic resin water emulsion type pressure-sensitive adhesive obtained by the above method is applied to one surface of the release film by a roll coater method, and dried at 120 ° C. for 60 seconds, and a 15 μm-thick acrylic viscous adhesive is applied to the surface of the release film. An agent layer was provided.

An unstretched ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) film formed by a T-die extrusion method is stretched 3.0 times in the longitudinal direction at 50 ° C., and further heat-set at 60 ° C. Uniaxially stretched EVA with a thickness of 120 μm
Film. One side of the uniaxially stretched EVA film was subjected to a corona discharge treatment to obtain a base film.

Next, the corona discharge treated surface of the base film was superposed and laminated on the surface of the acrylic pressure-sensitive adhesive layer provided on the surface of the release film, and 2 kg / cm ²
The pressure-sensitive adhesive layer was transferred to the surface of the substrate film to obtain an adhesive film for protecting the surface of a semiconductor wafer having an adhesive force of 270 g / 25 mm and a heat shrinkage at 70 ° C. of 35%.

Example 1 The adhesive film for protecting the surface of a semiconductor wafer obtained above was applied to a silicon mirror wafer (diameter 8) having scribe lines having a width of 100 μm and a depth of 5 μm formed on the surface at an interval of 1 cm to the end face. Inches, thickness of 700 μm) and supplied to a back surface grinding machine. In the grinder, first, rough grinding and then finish grinding were performed to reduce the wafer thickness to 100 μm. As shown in FIG. 1, the back-ground semiconductor wafer (2) to which the adhesive film (1) was attached was placed on the back side of a vacuum chuck table (3). ), And hot water (5) at 70 ° C. is supplied from the nozzle (4) to the interface (6) between the pressure-sensitive adhesive layer (1b) and the wafer at a rate of 5 liters per minute, and as shown in FIG. ) Shrinks and peels off, the peeling interface (6)
The adhesive film (1) for protecting the surface of the semiconductor wafer was peeled off and dropped by continuously supplying hot water to the wafer, and the adhesive film (1) was removed from the wafer. At this time, the wafer was not damaged due to the peeling of the adhesive film. ESCA measurement was performed on a portion of the mirror wafer surface after the back surface grinding that was not subjected to the scribe line processing. As a result, the C / Si value at the center of the wafer was 0.14 on average at three points, and the C / Si value at the end face was 0.14.
The / Si value was 0.13 on average at three points, which was a contamination level that was practically no problem.

COMPARATIVE EXAMPLE 1 As shown in FIG. 3, a semiconductor wafer (2) was fixed to a vacuum chuck table (3) on the back surface of a wafer, as shown in FIG. From the center of the semiconductor wafer on the side of the adhesive film (1), hot water at 70 ° C. was supplied at a rate of 5 liters / minute from the nozzle (7) to peel off the adhesive film (1). At this time, breakage was observed around the wafers for the five wafers. In addition, ESCA measurement was performed on the wafer that had not been damaged in the same manner as in Example 1. As a result, the C / Si value at the center of the wafer was 0.33 on average at three points,
The C / Si value of the end face was 0.32 on average at three points, a level that required further cleaning of the wafer surface after the peeling step.

Comparative Example 2 Adhesive films were peeled off by immersing in a 70 ° C. water bath about 50 semiconductor wafers whose back surfaces were ground in the same manner as in Example 1. At this time, 22 wafers were damaged due to shrinkage and peeling of the adhesive film. Also,
ESCA measurement was performed on the wafer that did not cause damage in the same manner as in Example 1. As a result, C /
The Si value was 0.56 at the average of three points, and the C / Si value of the end face was 0.32 at the average of three points, which was a level that required further cleaning of the wafer surface after the peeling step.

[0061]

According to the present invention, when the heat-shrinkable adhesive film for protecting the surface of a semiconductor wafer is peeled off from the surface of the semiconductor wafer after the back surface grinding, the adhesive is applied while the wafer is fixed to the chuck table as described above. By actively supplying hot water to the interface between the agent layer and the wafer, the shrinkage of the base film is relatively selectively generated from the end face, and the hot water capillary action between the pressure-sensitive adhesive layer and the wafer is caused. The adhesive film is peeled while promoting the penetration and reducing the adhesive strength of the adhesive film. Thereby, in the peeling step of the adhesive film for protecting the surface of the semiconductor wafer, the load on the wafer at the time of peeling is reduced, and the adhesive film can be easily peeled without damaging the wafer. Further, since the process can be performed with a simple device, the peeling device can be provided in the wafer back surface grinding machine, which leads to simplification of the process.
Furthermore, if the composition of the pressure-sensitive adhesive is selected, the peeling operation can also serve as the cleaning of the wafer surface, and the process can be further rationalized.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a state in which hot water is supplied to an interface between a wafer surface and an adhesive layer at an end face position of a semiconductor wafer and an adhesive film when performing a peeling method according to the present invention.

FIG. 2 is an explanatory view showing a state in which hot water is continuously supplied to an interface between the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film and the wafer surface where the pressure-sensitive adhesive film is partially peeled off in the present invention.

FIG. 3 is an explanatory view showing a state in which hot water is supplied to an adhesive film at a central portion of a semiconductor wafer for comparison with the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor wafer surface protection adhesive film 1a Base film 1b Adhesive layer 2 Semiconductor wafer 3 Chuck table 4 Nozzle 5 Hot water 6 Interface between adhesive layer and wafer 7 Nozzle

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kentaro Hirai 2-1-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi Prefecture Inside Mitsui Chemicals, Inc. (72) Inventor Sekitoshi Kumagai 2-1-1, Tango-dori, Minami-ku, Nagoya-shi, Aichi Prefecture Address: Mitsui Chemicals, Inc.

Claims (1)

[Claims] 1. A heat-shrinkable substrate film (1a)
A semiconductor wafer surface protecting adhesive film (1) having an adhesive layer (1b) provided on one surface thereof is adhered to the surface of a semiconductor wafer (2), and the back surface of the wafer (2) is ground. In the method in which (1) is heated and shrunk to be peeled off, after grinding the back surface of the semiconductor wafer (2), the pressure-sensitive adhesive layer (1b) of the adhesive film (1) is fixed while the wafer is fixed to the chuck table (3). ) And a hot water (5) supplied to an interface (6) between the wafer and the wafer surface to shrink the pressure-sensitive adhesive film (1) and peel it off from the wafer surface. .