JPH11238710A - Production of semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a semiconductor wafer against crackings, while shortening the working time by polishing the rear surface of the wafer after a protective adhesive tape has been pasted to the surface thereof and then stripping the protective adhesive tape from the surface of the semiconductor wafer through heating. SOLUTION: The surface of the adhesive layer in an adhesive tape for surface protection of a semiconductor wafer is exposed and pasted via the adhesive layer to the side of the semiconductor wafer, where an integrated circuit is built in. The semiconductor wafer is then fixed to the chuck table of a grinder, or the like, via the basic material film layer of the adhesive tape, and the rear side of the semiconductor wafer is polished. Subsequent to the end of the grinding, the adhesive tape is heated in the grinder and stripped off from the surface of the semiconductor wafer. According to the method, the wafer can be protected against crackings, and a series of work steps can be carried out in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing a semiconductor wafer. More specifically, after a heat-shrinkable adhesive tape for protecting the surface of a semiconductor wafer is attached to a surface of a semiconductor wafer such as a silicon wafer on which the integrated circuit is incorporated (hereinafter, referred to as a wafer surface), a semiconductor wafer backside grinding machine is used. To grind the surface of the semiconductor wafer on which the integrated circuit is not incorporated (hereinafter referred to as the wafer back surface), and subsequently, in a grinder, heat the adhesive tape to peel off the adhesive tape from the wafer surface; The present invention relates to a method for manufacturing a semiconductor wafer.

[0002]

2. Description of the Related Art Normally, a semiconductor integrated circuit (hereinafter, referred to as an IC) is formed 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. The wafer is manufactured by a method of grinding the back surface of the wafer by grinding, etching, lapping, or the like, reducing the thickness to about 200 to 400 μm, and then dicing into chips. In summary, after the IC formation is completed, there are four steps: a step of attaching an adhesive tape to the surface of the semiconductor wafer, a step of grinding the back surface of the semiconductor wafer, a step of peeling the adhesive tape, and a step of cleaning the surface of the semiconductor wafer. After that, it is formed into chips in a dicing process. Usually, when a semiconductor wafer is transferred between these manufacturing steps, the semiconductor wafer is stored in a cassette and transferred. That is, in each step, the unit operation of taking out from the cassette and storing in the cassette is repeated. These operations have caused not only a larger cause of damage to the wafer but also a complicated process and a loss of operation time due to the recent tendency of thinning and increasing the diameter.

In recent years, as the size of semiconductor chips has been reduced, the thickness of wafers has become thinner. Conventionally, the thickness of wafers after back grinding was about 200 to 400 μm. Is reduced to about 150 μm. Also, regarding the size, the diameter was conventionally 8 inches at the maximum, but 12 inches, and even 1 inch.
It tends to be up to 6 inches. In such a situation where the thickness of the semiconductor wafer is reduced and the diameter of the semiconductor wafer is increased, the semiconductor wafer after the rear surface is ground is more likely to be warped, and the adhesive tape is stuck on the surface of the wafer. The tendency is further enhanced by the tension of the adhesive tape. Therefore, after the back surface grinding, the thinned semiconductor wafer comes into contact with the cassette accommodating opening when being accommodated in the cassette, and is more easily damaged even when a slight impact is applied.

In the grinding process of the back surface of the semiconductor wafer, an adhesive tape for protecting the wafer surface is adhered to the wafer surface for the purpose of protecting the IC formed on the surface of the semiconductor wafer, preventing the semiconductor wafer from being damaged by grinding stress, and the like. You. Since the adhesive tape becomes unnecessary after the grinding of the back surface of the wafer is completed, the adhesive tape is peeled off from the wafer surface by the adhesive tape peeling device. As a method of peeling, for example, Japanese Unexamined Patent Publication
No. 8950 discloses a method in which a tape having a strong adhesive force called a release tape is adhered to a base film surface of an adhesive tape adhered to a semiconductor wafer surface, and the adhesive tape is peeled off via the release tape. . However, as described above, in a situation where the thickness of the semiconductor wafer is reduced and the diameter of the semiconductor wafer is increased, when the semiconductor wafer having a large warp is attracted to the chuck table of the grinding machine, or when the adhesive tape is separated from the semiconductor wafer. In addition, the semiconductor wafer is easily damaged.

[0005] In order to prevent the wafer from being damaged when the adhesive tape is peeled off from the surface of the semiconductor wafer, there has been proposed a surface protection film having improved peelability. For example, JP
Japanese Patent Application Laid-Open No. 189938 discloses an adhesive comprising a light-transmissive support and a pressure-sensitive adhesive provided on the support and having a property of being hardened by light irradiation and formed into a three-dimensional network when polishing the back surface of a semiconductor wafer. A method is described in which a film is adhered to the surface of a wafer, and after polishing, the adhesive film is irradiated with light to peel off the adhesive film without damaging the wafer. However, the pressure-sensitive adhesive (pressure-sensitive adhesive layer) disclosed in the present invention and having the property of being cured by light irradiation and forming a three-dimensional network is a pressure-sensitive adhesive layer that is polymerized by radical polymerization. If oxygen enters between the layers, the curing reaction does not proceed sufficiently due to the effect of inhibiting polymerization of oxygen, and the uncured adhesive with low cohesion may contaminate the wafer surface during peeling after grinding the back surface of the wafer. Was. There are complicated irregularities on the surface of the wafer in which the integrated circuit is incorporated, and it is extremely difficult to attach the integrated circuit without entering any air (oxygen). In addition, it is necessary to newly install a device to create a system from which oxygen is removed for sticking. In some cases, such contamination due to the adhesive can be removed by washing with a solvent or the like, but in most cases, it cannot be completely removed at present. Furthermore, in this method, no advantage can be found with respect to prevention of breakage of the wafer and shortening of operation time when the wafer is transferred to the adhesive tape peeling step after grinding the back surface of the wafer.

[0006]

As described above, under the circumstances where the diameter and thickness of the semiconductor wafer are to be increased and the thickness of the semiconductor wafer is to be improved, the non-contamination of the wafer surface and the prevention of damage during grinding of the back surface of the wafer are required. It is desired to provide a semiconductor wafer manufacturing method which can maintain the same level of performance and the like as before, do not damage the wafer when peeling the adhesive tape and transport the wafer between processing steps, and can shorten the working time. It is rare.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to prevent a semiconductor wafer from being cracked when the semiconductor wafer is transferred, when the adhesive tape for protecting the semiconductor wafer surface is peeled off, and the like.
It is an object of the present invention to provide a method for manufacturing a semiconductor wafer, which can shorten the operation time.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above-mentioned object, and as a result, have adopted a heat-shrinkable adhesive tape for protecting the surface of a semiconductor wafer and put it on the wafer surface. After bonding, the backside grinding is performed in a semiconductor wafer backside grinding machine, and subsequently, the adhesive tape is heated in the same grinding machine, so that the adhesive tape can be easily peeled without damaging the semiconductor wafer. The present invention has been completed, and it has been found that the conventional next step of peeling off the adhesive tape can be omitted.

That is, the present invention relates to a method for manufacturing a semiconductor wafer, wherein an adhesive tape is adhered to the surface of a semiconductor wafer, the back surface of the semiconductor wafer is ground using a grinder, and then the adhesive tape is peeled off. Using an adhesive tape having heat shrinkability as an adhesive tape, and after grinding the back surface of the semiconductor wafer, subsequently heating the adhesive tape in a grinding machine to peel off the semiconductor wafer from the surface of the semiconductor wafer, It is a manufacturing method.

In the present invention, a preferred method of heating the pressure-sensitive adhesive tape in the grinding machine includes a method using at least one heat medium selected from the group consisting of hot water and hot air. The temperature of the heating medium is in the range of 50 to 99C, preferably in the range of 50 to 80C. Further, after the adhesive tape is peeled off in the grinder, the wafer surface may be subsequently washed with a washing liquid. In this case, it is preferable to use water, warm water, or the like as the cleaning liquid.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. An outline of the present invention is to release a release film from an adhesive layer of an adhesive tape for protecting a surface of a semiconductor wafer (hereinafter, referred to as an adhesive tape), to expose the surface of the adhesive layer, and through the adhesive layer to form a semiconductor wafer. On the surface (wafer surface) on the side where the integrated circuit is incorporated. Next, the semiconductor wafer is fixed to a chuck table or the like of a grinding machine via the base film layer of the adhesive tape, and the back surface of the semiconductor wafer is ground. After the grinding is completed, subsequently in the grinding machine,
The adhesive tape is heated to peel off the adhesive tape. Next, if necessary, the wafer surface is cleaned, and thereafter, the wafer is taken out of the grinder, stored in a cassette or the like, and transported to the next process such as a dicing process.

The pressure-sensitive adhesive tape used in the present invention is obtained by forming a pressure-sensitive adhesive layer on one surface of a heat-shrinkable base film. In order to protect the pressure-sensitive adhesive layer during storage, transportation and the like, it is preferable that a release film usually called a separator is attached to the surface of the pressure-sensitive adhesive layer. In the method for producing the pressure-sensitive adhesive tape, first, a pressure-sensitive adhesive is applied to one surface of a release film, dried to form a pressure-sensitive adhesive layer, and then transferred to the surface of a heat-shrinkable base film. As the substrate film having heat shrinkability, 50 to 99 ° C., preferably 5 to 99 ° C.
It is preferable that the heat shrinkage in the uniaxial direction or the biaxial (longitudinal, horizontal) direction at 0 to 80 ° C. is in the range of 5 to 50%.

The release film is essentially a film having a surface tension lower than that of the base film regardless of the absolute value of the surface tension. In addition, the heat resistance of the release film affects the drying property of the adhesive applied to the surface. If the heat resistance is low, the drying temperature of the pressure-sensitive adhesive must be low, and it takes a long time to dry, and it is not possible to dry efficiently in a short time. Also, for example,
The release film may cause heat shrinkage in the drying oven,
Problems such as generation of wrinkles in the release film may occur, and a pressure-sensitive adhesive layer having a uniform thickness may not be formed. From such a viewpoint, the release film preferably has a predetermined heat resistance. As a criterion for determining heat resistance, it is preferable to have a Vicat softening point of 100 ° C. or higher. The type of the release film is not particularly limited as long as the above conditions are satisfied. It may be a single-layer film or a laminated film, and can be appropriately selected from commercially available products.

Specific examples of the release film include a film produced from high-density polyethylene, polypropylene, polyethylene terephthalate, polyamide resin or the like, or a mixture thereof. Preferably, a high-density polyethylene film, a polypropylene film, a polyethylene terephthalate film, or the like is used. There is no particular limitation on the production method of these films,
It may be manufactured by a known method such as an extrusion molding method or a calendar molding method, and the molding temperature may be any temperature as long as it is higher than the glass transition point or softening point of the raw material resin and lower than the decomposition temperature.

For the purpose of reducing the peeling stress of the pressure-sensitive adhesive layer from the release film, a silicone-based release agent may be applied to the surface of the release film to which the pressure-sensitive adhesive is applied so long as the pressure-sensitive adhesive layer is not contaminated. No problem. The thickness of the release film depends on the drying conditions, the type and thickness of the adhesive layer,
Alternatively, the thickness is usually 10 to 1000 μm, although it varies depending on the processing conditions, processing method, and the like of the adhesive tape. Preferably 20
１００100 μm.

The heat shrinkability of the pressure-sensitive adhesive tape affects the releasability from the semiconductor wafer surface. If the shrinkage is too low, poor peeling may occur during heating, or peeling may take time. On the other hand, if the shrinkage is too high, the adhesive tape is deformed due to a change with time during storage, and the workability when attaching the adhesive tape to the wafer surface is reduced. From this perspective,
The heat shrinkage of the pressure-sensitive adhesive tape at 50 to 99 ° C, preferably 50 to 80 ° C, is preferably 5 to 50%.
In this case, any tape that exhibits the above-described heat shrinkability at at least one point in the above temperature range may be used. The contraction direction may be a uniaxial direction or a biaxial (longitudinal, lateral) direction.
The type of material is not particularly limited. To give a concrete example,
Ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, polybutadiene copolymer, polybutadiene, soft vinyl chloride resin, polyolefin, polyester, polyamide, ionomer and other resins, and copolymer elastomers thereof, and diene-based And nitrile-based and acrylic-based films. 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 obtained by forming a resin having a Shore D-type hardness of 40 or less specified in ASTM-D-2240 into a film shape, For example, an ethylene-vinyl acetate copolymer (hereinafter, referred to as EVA) film, a polybutadiene film, or the like is preferably used. In this case, a film harder than the surface of the base film opposite to the surface on which the pressure-sensitive adhesive layer is provided, specifically,
It is preferable to laminate a heat-shrinkable film obtained by molding a resin having a Shore-D hardness of more than 40 into a film shape. This increases the rigidity of the adhesive tape,
Adhering workability and peeling workability are improved.

The thickness of the substrate film is appropriately determined according to the shape and surface condition of the semiconductor wafer to be protected, the grinding method and grinding conditions, or the workability such as cutting and sticking of the adhesive tape for protecting the wafer surface. , 10 to 1000 μm. Preferably it is 100 to 300 μm.

The method for producing the base 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 adhesive tape is peeled off from the wafer surface after grinding the back surface of the wafer. When the stretching ratio is low, when the film is heated when peeled from the wafer surface, the base film does not sufficiently shrink, and the peelability, workability, and the like are 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 may be either uniaxial stretching in which the film is stretched in the machine direction or transverse direction, or biaxial stretching in which the film is stretched in the machine direction and transverse direction. 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, and there are no specific limitations on the stretching method, such as a roll rolling method, a longitudinal uniaxial stretching method using a roll stretching method, a vertical and horizontal biaxial stretching method using a tenter machine, and a simultaneous vertical and horizontal biaxial stretching method using a tenter machine. 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 subjected to a heat treatment so as not to cause shrinkage over time. The heat treatment temperature is
The temperature is preferably 45 to 80 ° C. Of the base film,
At least the surface tension of the surface where the adhesive is to be laminated is
It is necessary that the surface tension of the release film be higher than the surface tension of the surface on which the pressure-sensitive adhesive layer is formed. As the base film, a film having a surface tension higher than the surface tension of the release film can be generally used regardless of the absolute value of the surface tension. In consideration of the adhesiveness of the pressure-sensitive adhesive layer after transfer from the release film, it is preferable to select the film based on a stretched film having a surface tension of 35 dyne / cm or more. If the surface tension is low, the adhesion between the pressure-sensitive adhesive layer and the substrate film is reduced, and transfer of the pressure-sensitive adhesive layer from the release film cannot be performed well. Examples of a method for increasing the surface tension of the base film include a corona discharge treatment.

The composition of the pressure-sensitive adhesive is not particularly limited and can be appropriately selected from commercially available products. However, an acrylic pressure-sensitive adhesive is preferred from the viewpoints of tackiness, applicability, and non-staining property of the wafer surface.
Such an acrylic pressure-sensitive adhesive is obtained by copolymerizing a monomer mixture containing an alkyl acrylate monomer and a monomer having a carboxyl group. Furthermore,
If necessary, a vinyl monomer, a polyfunctional monomer, an internally crosslinkable monomer, and the like copolymerizable therewith can be copolymerized.

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 carboxyl group include acrylic acid, methacrylic acid, crotonic acid,
Examples include itaconic acid, maleic acid, and fumaric acid. Examples of the vinyl monomer copolymerizable with the alkyl acrylate monomer and the monomer having a carboxyl group include, for example, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, acrylamide, methacrylamide, dimethylaminoacrylate, dimethyl Examples include amino methacrylate, vinyl acetate, styrene, acrylonitrile and the like.

The polymerization reaction mechanism of the pressure-sensitive adhesive polymer includes:
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, as a radical polymerization initiator, benzoyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, dibutyl butyl peroxide,
Organic peroxides such as jitter amyl peroxide,
Inorganic peroxides such as ammonium persulfate, potassium persulfate and sodium persulfate, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 4,4′-azobis- Azo compounds such as 4-cyanovaleric acid; and the like.

When the polymerization is carried out by the emulsion polymerization method, among these radical polymerization initiators, water-soluble inorganic peroxides such as 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 cross-linking agent having two or more cross-linkable functional groups in one molecule used in the present invention is used to react with the functional group of the pressure-sensitive adhesive polymer to adjust the adhesion and cohesion. As the crosslinking agent, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether,
Epoxy compounds such as pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, resorcin diglycidyl ether, tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate of trimethylolpropane 3 Adducts, isocyanate compounds such as polyisocyanates, 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 Down-2,4-bis - aziridine carboxyamide), trimethylolpropane - tri-.beta.-(2-methyl aziridine) aziridine compounds such as propionate, and melamine-based compounds such as hexamethoxymethylolmelamine the like.

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 usually within such a range that the number of functional groups in the cross-linking agent does not become larger than the number of functional groups in the pressure-sensitive adhesive polymer. However, when a new functional group is generated by the crosslinking reaction, when the crosslinking reaction is slow, or the like, an excessive amount may be added as necessary. Usually, the adhesive strength of the adhesive tape for grinding a wafer back surface is 10 to 1000 g / 25 mm, preferably 3 when converted to the adhesive strength to a SUS-BA plate.
It is about 0 to 600 g / 25 mm. The above range is adjusted in consideration of the grinding conditions of the back surface of the wafer, the diameter of the wafer, the thickness of the wafer after grinding, and the like. As a guide, it is adjusted by adding 0.1 to 30 parts by weight of a crosslinking agent to 100 parts by weight of the tackifier polymer. Preferably it is 0.3 to 15 parts by weight.

If necessary, a surfactant or the like can be added to the pressure-sensitive adhesive to such an extent that the surface of the wafer is not contaminated. The nonionic or anionic surfactant can be used as long as it does not contaminate the wafer surface. Examples of the nonionic surfactant include polyoxyethylene octyl phenyl ether, polyoxyethylene ninyl phenyl ether, and polyoxyethylene lauryl ether. As anionic surfactants, alkyl diphenyl ether disulfonates and salts thereof, bisnaphthalene sulphonates and salts thereof, polyoxyalkyl sulfosuccinates and salts thereof, polyoxyethylene phenyl ether sulfates and salts thereof, etc. 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 a pressure-sensitive adhesive coating solution to one surface of a base film or a 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 employed. The drying condition of the applied pressure-sensitive adhesive is not particularly limited, but is generally 80 to 200.
It is preferable to dry in a temperature range of 10C for 10 seconds to 10 minutes. More preferably, drying is performed at 80 to 170 ° C. for 15 seconds to 5 minutes. The thickness of the pressure-sensitive adhesive layer is appropriately determined depending on the surface condition, shape, and back surface grinding method of the semiconductor wafer. Adhesive force when the back surface of the semiconductor wafer is ground, peelability after the grinding is completed, and the like are determined. Considering this, it is usually about 2 to 100 μm. Preferably it is about 5 to 70 μm.

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. To wear. 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 peeling of the release film from the surface of the pressure-sensitive adhesive layer is preferably immediately before use as a pressure-sensitive adhesive tape. The pressure-sensitive adhesive tape obtained in this manner is rolled or cut into a predetermined shape, and then provided for storage, transportation, and the like.

Next, a series of methods for manufacturing a semiconductor wafer from sticking the above-mentioned adhesive tape on the surface of the semiconductor wafer to the dicing step will be described in detail.

In the present invention, the pressure-sensitive adhesive tape is adhered to the surface of the semiconductor wafer via the pressure-sensitive adhesive layer. The operation of adhering the adhesive film to the surface of the semiconductor wafer may be performed manually, but is usually performed by an apparatus called an automatic adhering machine to which a roll-shaped adhesive film is attached. For example, Takatori Co., Ltd.
Model: ATM-1000B, ATM-1100, manufactured by Teikoku Seiki Co., Ltd. Model: STL series, etc.

Then, the semiconductor wafer is fixed to a chuck table or the like of a wafer back surface grinding machine via the base film layer of the adhesive tape. The back surface of the wafer is ground by a grinder until a predetermined thickness is obtained. It is common that cooling water is injected into a grinding surface during grinding. As the back surface grinding method, a known grinding method such as a through feed method and an in-feed method is employed. The thickness of the semiconductor wafer is 500 to 1000 μm before grinding, but is ground to 80 to 400 μm, preferably about 80 to 200 μm after grinding. Usually, the thickness of the semiconductor wafer before grinding is appropriately determined depending on the diameter, type, etc. of the wafer,
The thickness after grinding is appropriately determined depending on the size of the obtained chip, the type of IC, and the like.

After the grinding is completed, grinding chips and the like are removed by, for example, pouring pure water into the grinding surface. Then, the wafer is rotated halfway up and down and fixed to the chuck table via the back surface of the wafer. Next, the adhesive tape is peeled from the wafer surface by heating the adhesive tape to shrink the base film layer. The peeled adhesive tape is removed out of the system by a method such as suctioning a dedicated jig.

Here, the state in which the adhesive tape has peeled off means
The adhesive tape stuck on the wafer surface is
%. In this case, the other part of the heated adhesive tape is deformed by heat shrinkage, and is easily removed. Although the detailed peeling mechanism is not clear, for example, when heating and peeling using warm water, even in a part that is not in a peeled state, a state in which warm water has entered most of the interface between the wafer surface and the adhesive layer. ing. In addition, even in the case of peeling with hot air, partial lifting occurs due to the deformation stress of the base film at the interface between the wafer surface and the adhesive layer.

The heating method is not particularly limited as long as the pressure-sensitive adhesive tape adhered to the wafer surface can be shrunk by heating, but hot water of 50 to 99 ° C., preferably 50 to 80 ° C. is poured onto the surface of the adhesive tape. Method, 50 ~ with wafer
The adhesive tape is immersed in hot water at 99 ° C., preferably 50 to 80 ° C., or the like, for example, at 50 to 99 ° C.,
A method of contacting with hot water of 80 to 80 ° C, a method of blowing hot air of 50 to 99 ° C, preferably 50 to 80 ° C, and the like. In consideration of the thermal conductivity to the adhesive tape for shrinking the base film, a method of contacting hot water at 50 to 99 ° C, preferably 50 to 80 ° C with the adhesive tape is preferable. Further, in consideration of simultaneous cleaning of the wafer surface in the grinder after peeling off the adhesive tape, it is preferable to heat the adhesive tape surface by injecting warm water at the above temperature. In this case, it is preferable to supply the hot water while rotating the wafer at a rotation speed of 5 to 500 rpm, considering that the hot water is supplied evenly to the base film surface of the adhesive tape to further facilitate the peelability. . The method of rotating the wafer may be plane rotation using the center of the wafer as the center of rotation.

In the present invention, a cleaning liquid such as pure water or alcohol is supplied to the wafer surface after the adhesive tape has been peeled off.
Can be washed. It is preferable to use pure water as the cleaning liquid. By adopting these methods,
Usually, a dedicated cleaning process performed after the wafer back surface grinding process can be omitted, and a series of processes from the wafer back surface grinding process to the surface cleaning process can be simplified, and the operation time can be reduced. .

The heating temperature is appropriately selected in the range of 50 to 99 ° C., preferably 50 to 80 ° C. depending on the stretching ratio of the base film, the adhesive strength of the tape for protecting the surface of the semiconductor wafer, and the kind of heating method. obtain. The heating time also affects the peelability from the semiconductor wafer surface. The heating time varies depending on the stretching ratio of the base film and the heating temperature, but is preferably 1 to 60 seconds, preferably 1
0 to 30 seconds.

Conventionally, after grinding of the back surface of a wafer is completed, the wafer is housed in a cassette, transported to an adhesive tape peeling step, the cassette is set in a peeling machine, taken out of the cassette, and the adhesive tape is peeled. Was adopted. Further, a method has been adopted in which after the adhesive tape is peeled off, the wafer is again housed in a cassette, transported to a cleaning step, taken out of the cassette and set in a cleaning machine to clean the wafer surface.
When the wafer is transferred to the cleaning process, it is stored and removed from the cassette with the adhesive tape adhered to the wafer surface. Therefore, the wafer is thinly ground to a thickness of 200 μm or less. In such a case, the wafer is significantly warped, and the wafer often receives an impact and breaks when the wafer comes into contact with the storage port of the cassette. When the diameter was 12 inches or more, even if the thickness after grinding was about 400 μm, significant warpage occurred.

On the other hand, in the method of the present invention, the adhesive tape is peeled off by heating in the back surface grinding machine, and the cleaning process of the wafer surface is carried out. Therefore, there is no need to store the wafer thinned by the back surface grinding in a cassette and transport it to the peeling step and further to the cleaning step. Therefore, the number of operations for storing the wafer in the wafer transfer cassette and the operations for removing the wafer from the cassette are extremely small. In particular, since the transfer from the back surface grinding step to the peeling step can be omitted, it is possible to prevent the wafer from being cracked at the time of being stored in the cassette and at the time of being taken out due to the warpage of the wafer. In addition, the wafer surface cleaning step can be omitted by cleaning the wafer surface with a cleaning liquid such as pure water or alcohol in the grinder after back surface grinding, heating and peeling of the adhesive tape. Finally, the wafer is moved from 1000 to 10000 rpm.
A series of steps is completed by drying by a method such as high-speed rotation. The size of the semiconductor wafer to which the present invention can be applied is 6 to 16 inches in diameter, preferably 6 to 12 inches.
It has a large diameter of inches.

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 tape (%) An arbitrary portion of the adhesive tape is selected, and a length of 10 c
Prepare 15 square m-shaped sample pieces. After peeling the release film from the sample piece, the film is heated in an air oven at 25 ° C., 50 ° C. and 80 ° 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 rate [｛(L ₁ ) − (L) is determined from the length before heating (L ₁ ) and the length after heating (L ₂ ). ₂ )｝ / (L ₁ )] X100
(%). The measurement is performed five times under each condition, and the average value is obtained.

(2) Measurement of Wafer Surface Contamination by ESCA An 8-inch silicon mirror wafer was cut into 1 cm squares using a diamond cutter so as not to contaminate the surface. The surface of the cut wafer was measured using ESCA under the following conditions, and the ratio of carbon to silicon (hereinafter referred to as C / Si ratio) was measured.
And investigate the state of contamination of the silicon wafer with organic matter. <ESCA measurement conditions and C / Si ratio calculation method> X-ray source: M
gKα ray (1253.6 eV), X-ray output: 300 W,
Measurement vacuum degree: 2 × 10 −7 Pa or less, C / Si: (peak area of carbon) / (peak area of silicon) <Evaluation method of C / Si ratio> C of silicon mirror wafer surface before attaching sample The / Si value is 0.10 (blank value). Therefore, a sample having a C / Si value of about 0.10 to 0.12 on the surface of the silicon mirror wafer after attaching the sample is determined as having no contamination, and a sample having a C / Si value exceeding the range is determined as having contamination.

(3) Measurement of Adhesive Strength At 23 ° C., 5 × 20 cm of S
It is stuck on the surface of a US-BA plate and left for 1 hour. Hold one end of the sample, peel angle 180 °, peel speed 300mm
/ Min. Is used to measure the stress when the sample is peeled from the SUS-BA plate, and converted to g / 25 mm.

Example 1 In a polymerization reactor, 148 parts by weight of deionized water and ammonium salt of polyoxyethylene nonyl phenyl 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-41-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. Emulsion polymerization was carried out at 9 ° 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, an aziridine-based crosslinking agent (Nippon Shokubai Chemical Industry Co., Ltd.)
(Trade name: Chemitite PZ-33) (2 parts by weight) and diethylene glycol monobutyl ether (5 parts by weight) as a film-forming aid were added to obtain an adhesive coating solution.

50 μm thick film formed by T-die extrusion
m, Vicat softening point 140 ° C, surface tension on one side is 30
Using a polypropylene film having a dyne / cm 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 100 ° C. for 60 seconds. An acrylic tackifier layer having a thickness of 10 μm was provided on the surface of the release film.

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 is heat-fixed at 60 ° C. A uniaxially stretched EVA film having a thickness of 120 μm was obtained. One surface of the uniaxially stretched EVA film was subjected to a corona discharge treatment to have a surface tension of 50 dyne / cm and used as a base film.

The surface of the acrylic pressure-sensitive adhesive layer provided on the surface of the release film was laminated with the corona-discharge treated surface of the substrate film superimposed thereon, and pressed at a pressure of ² kg / cm ² ,
The pressure-sensitive adhesive layer was transferred to the surface of the base film to obtain a pressure-sensitive adhesive tape having a pressure of 200 g / 25 mm. The results of measuring the heat shrinkage of the pressure-sensitive adhesive tape at each temperature by the above method are shown in Table 1.

The obtained adhesive tape was adhered to the surface of 50 mirror wafers having a diameter of 8 inches and a thickness of 700 μm, and was supplied to a back surface grinding machine. In the grinder, rough grinding was performed first, then finish grinding, and finally back surface cleaning was performed. That is, the mirror wafer is ground at a grinding speed of 300 μm /
Coarse grinding to a thickness of 170 μm in minutes and then 20 μm /
And finish grinding to 120 μm. Finally, after cleaning the back surface, the wafer is further turned halfway so that the front and back are reversed, hot water of 60 ° C. is poured on the adhesive tape stuck on the wafer surface for 10 seconds, and then, while rotating the wafer at 500 rpm, Further, hot water at 60 ° C. was injected for 10 seconds, and the adhesive tape was peeled off. After rotating at 3000 rpm and drying,
The wafer was taken out of the grinding machine and stored in a cassette. 5
All zero wafers could be stored without damage. The time from the start of grinding to the storage was 150 minutes. The results obtained are shown in [Table 1].

Example 2 After grinding the back surface, the semiconductor wafer was ground in the same manner as in Example 1 except that the adhesive tape was heated with hot air at 80 ° C. for 30 seconds, and the tape was peeled off. All 50 wafers were stored without damage. The time from the start of grinding to the storage was 160 minutes. The results obtained are shown in [Table 1].

Example 3 The same procedure as in Example 1 was carried out until the adhesive tape was peeled off. Further, the wafer was washed with pure water for 3 minutes while rotating at a rotation speed of 1000 rpm, and then dried at 3000 rpm to take out the wafer. Was. All 50 wafers were stored without damage. The time from the start of grinding to the storage was 160 minutes. The surface contamination of the stored 8-inch mirror wafer was measured by the above method. The results obtained are shown in [Table 1].

Example 4 A mirror wafer having a diameter of 6 inches and a thickness of 600 μm was used in the same manner as in Example 3 except that the thickness after rough grinding was 150 μm and the thickness after finish grinding was 80 μm. The semiconductor wafer was ground, the tape was separated, and the wafer was cleaned. As a result, all 50 wafers were accommodated without damage. The time from the start of grinding to the accommodation was 160 minutes. The results obtained are shown in [Table 1].

Comparative Example 1 One side of an unstretched EVA film having a thickness of 120 μm was subjected to a corona discharge treatment to have a surface tension of 50 dyne / cm.
An adhesive tape was obtained in the same manner as in Example 1 except that this was used as a substrate film. The obtained pressure-sensitive adhesive tape has a diameter of 8
The wafer was adhered to the surface of 50 mirror wafers having a thickness of 700 μm and supplied to a back surface grinding machine. After performing rough grinding and finish grinding in the same manner as in Example 1 in the back surface grinding machine, the back surface was washed and dried, and then stored in a cassette.

Next, the tape was peeled off by applying to an adhesive tape peeling device. When the wafer was taken out of the back grinding machine and stored in the cassette, the wafer came into contact with the storage opening of the two-sheet cassette and was damaged. In the adhesive tape peeling device,
Before peeling the tape, one sheet was damaged when the wafer was attracted to the chuck table, and four sheets were damaged when the tape was peeled. The time from the start of grinding to the storage after peeling off the tape was 190 minutes. The results obtained are shown in [Table 1].

Comparative Example 2 The same procedure as in Comparative Example 1 was carried out until the tape was peeled off. Thereafter, the wafer was subjected to a cleaning step, and preliminary cleaning and main cleaning were performed in a cassette type overflow cleaning tank for 3 minutes and 5 minutes, respectively.
Minutes. Next, it was dried with a rotary dryer. When the wafer was taken out of the back grinding machine and stored in the cassette, the wafer came into contact with the storage opening of the two-sheet cassette and was damaged. Further, in the adhesive tape peeling device for protecting the semiconductor surface, when the wafer is attracted to the chuck table before the tape is peeled, 1
One sheet and two pieces were damaged when the tape was peeled off. The time from the start of grinding to the storage after tape peeling was 190 minutes. further,
One sheet was damaged during transportation to the cleaning process. It took 220 minutes from the start of grinding to the end of cleaning. The surface contamination of the stored 8-inch mirror wafer was measured. The results obtained are shown in [Table 1].

[0058]

[Table 1]

[0059]

According to the method of the present invention, the diameter is 6 to 16
Inches, preferably 6 to 12 inches of semiconductor wafer with a thickness of 80 to 400 μm, preferably 80 to 20 μm.
Even when grinding to a thickness of about 0 μm, the semiconductor wafer is not damaged when the adhesive tape is peeled off after grinding the back surface. Also, because it is a method of peeling the adhesive tape using the heat shrinkage of the adhesive tape itself in the grinding machine,
For example, when a wafer is taken out of the grinding machine and stored in a cassette, no adhesive tape is attached to the surface of the wafer, and the warpage of the wafer is extremely small. Therefore, when the wafer is stored in the cassette, the wafer does not break due to the wafer coming into contact with the storage port of the cassette. Further, if the wafer surface is cleaned in the grinder, the transfer to the next cleaning step can be omitted.

According to the method of the present invention described above, a diameter of 6
The thickness of the back surface of the semiconductor wafer of up to 16 inches is 80 to 2
Even when grinding to a thickness of about 00 μm, the semiconductor wafer is not damaged when the adhesive tape is peeled off. In addition, since a method of peeling the adhesive tape by utilizing heat shrinkage in the grinder is adopted, for example, when a wafer is taken out from the grinder and stored in a cassette, the warpage of the wafer is extremely small. Therefore, when the wafer is stored in the cassette, the wafer does not break due to the wafer coming into contact with the storage port of the cassette. Furthermore, if the adhesive tape is heated and peeled in a grinding machine using hot water as a heating medium, and further washed with a washing liquid, a dedicated washing step conventionally performed in the next step can be omitted. Therefore, according to the present invention, a series of steps from grinding of the back surface of the semiconductor wafer to cleaning of the wafer surface can be performed in a short time, and the working time can be reduced.

Continuation of front page (72) Inventor Hideki Fukumoto 2-1-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi Mitsui Chemicals, Inc.

Claims (12)

[Claims] An adhesive tape is stuck on the surface of a semiconductor wafer, and the back surface of the semiconductor wafer is ground using a grinder.
A method of manufacturing a semiconductor wafer for peeling an adhesive tape, wherein a heat-shrinkable adhesive tape is used as the adhesive tape, and after the back surface of the semiconductor wafer is ground, the adhesive tape is subsequently heated in the grinding machine. And separating the semiconductor wafer from the surface of the semiconductor wafer. 2. The method according to claim 1, wherein the back surface of the semiconductor wafer having a diameter of 6 to 16 inches is ground to a thickness of 80 to 400 μm. 3. The method according to claim 2, wherein the back surface of the semiconductor wafer having a diameter of 6 to 16 inches is ground to a thickness of 80 to 200 μm. 4. The method according to claim 3, wherein the back surface of the semiconductor wafer having a diameter of 6 to 12 inches is ground to a thickness of 80 to 200 μm. 5. The semiconductor wafer according to claim 1, wherein the semiconductor wafer is heated to a temperature range of 50 to 99 ° C. using at least one heat medium selected from the group consisting of hot water and hot air. Method. 6. The method for manufacturing a semiconductor wafer according to claim 5, wherein the temperature of the heat medium is 50 to 80 ° C. 7. The method for manufacturing a semiconductor wafer according to claim 5, wherein heating is performed to a temperature range of 50 to 99 ° C. using hot water. 8. The method for manufacturing a semiconductor wafer according to claim 7, wherein the semiconductor wafer is heated to a temperature range of 50 to 80 ° C. using hot water. 9. The method according to claim 1, wherein the semiconductor wafer is heated while rotating at a rotation speed of 5 to 500 rpm.
3. The method for manufacturing a semiconductor wafer according to item 1. 10. The adhesive tape has a heat shrinkage of 50 to 99.
2. The method according to claim 1, wherein the temperature is 5% to 50% at a temperature of 10.degree.
3. The method for manufacturing a semiconductor wafer according to item 1. 11. The adhesive tape has a heat shrinkage of 50 to 80.
2. The method according to claim 1, wherein the temperature is 5% to 50% at a temperature of 10.degree.
0. The method for manufacturing a semiconductor wafer according to item 0. 12. The method for manufacturing a semiconductor wafer according to claim 1, wherein the adhesive tape is peeled off from the surface of the semiconductor wafer, and the surface of the semiconductor wafer is cleaned with a cleaning liquid.