JP2003059871A - Method of manufacturing ic chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an IC chip, by which a semiconductor wafer can be protected from breakage, etc., the handling performance of the semiconductor wafer can be improved, and the semiconductor wafer can be machined into IC chips satisfactorily, even if the thickness of the semiconductor wafer to be machined is about 50 μm. SOLUTION: This method of manufacturing an IC chip is such that, at least in the grinding process or a dicing process, a semiconductor wafer is machined, while a reinforced semiconductor wafer thin film is stuck to a grinding tape of a dicing tape. The reinforced semiconductor wafer thin film is reinforced by a support layer, made of thermosoftening resin whose storage elasticity E' (Pa), measured by a viscoelasticity measuring instrument under the conditions of the frequency being 10 Hz and a distortion is 0.1%, is changed with the changing rate of not less than 5 Pa/ deg.C at a firt-order phase transition temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents damage to a semiconductor wafer even when processing a semiconductor wafer having a thickness of about 50 μm, improves handleability, and favorably processes into an IC chip. The present invention relates to a method of manufacturing an IC chip capable of performing.

[0002]

2. Description of the Related Art A semiconductor integrated circuit (IC chip) is usually obtained by slicing a high-purity semiconductor single crystal or the like into a wafer, forming a predetermined circuit pattern on the wafer surface using a photoresist, and then forming the wafer. It is manufactured by grinding the back surface with a grinder to reduce the thickness of the wafer to about 100 to 600 μm, and finally dicing it into chips.

Here, at the time of the above-mentioned grinding, an adhesive sheet (grinding tape) is attached to the front surface of the wafer to prevent damage to the wafer and facilitate the grinding process. Adhesive sheets (dicing tape) are attached, and the wafer is diced in a state where the wafer is adhered and fixed, and the formed chips are picked up by pushing up with a needle from the film base material side of the dicing tape and fixed on the die pad.

In recent years, as the use of IC chips has expanded, semiconductor wafers having a thickness of about 50 μm which can be used for IC cards or used by laminating have been required. However, the thickness is 50μ
A semiconductor wafer of about m has a conventional thickness of 100 to 600.
Compared to a semiconductor wafer of about μm, it has a large warp and is easily cracked by an impact, so that it is inferior in handleability and may be broken when it is processed like a conventional semiconductor wafer.

Above all, a semiconductor wafer having a thickness of about 50 μm has a high risk of being damaged in a grinding process or a dicing process which is susceptible to an impact. Further, the yield is poor because the bumps are easily damaged when they are formed on the electrodes of the IC chip. For this reason, it has been an important issue to improve the handling of a semiconductor wafer having a thickness of about 50 μm in the process of manufacturing an IC chip.

[0006]

In view of the above situation, the present invention prevents breakage of a semiconductor wafer and improves handleability even when processing a semiconductor wafer having a thickness of about 50 μm. It is an object of the present invention to provide an IC chip manufacturing method capable of favorably processing an IC chip.

[0007]

SUMMARY OF THE INVENTION The present invention is a method for manufacturing an IC chip in which a reinforcing semiconductor wafer thin film is attached to a grinding tape or a dicing tape in at least a grinding step or a dicing step to process a semiconductor wafer. Therefore, the reinforced semiconductor wafer thin film has a storage elastic modulus E ′ (Pa) measured using a viscoelasticity measuring apparatus under the conditions of a frequency of 10 Hz and a strain of 0.1%, and a storage elastic modulus E ′ of 5 Pa / ° C. or more at a first-order phase transition temperature. It is a method for manufacturing an IC chip which is reinforced by a support layer made of a thermosoftening resin that changes in proportion. The present invention is described in detail below.

In the method of manufacturing an IC chip of the present invention, the semiconductor wafer is processed in the state of the reinforcing semiconductor wafer thin film at least in the grinding step or the dicing step. Examples of the semiconductor include silicon and gallium arsenide. The grinding step is performed after slicing a high-purity silicon single crystal, gallium arsenide single crystal, or the like into a semiconductor wafer and forming a predetermined circuit pattern on the wafer surface. The grinding step is a step of reducing the thickness of the wafer by grinding the back surface of the wafer with a grinder.

The dicing step is a step of cutting a wafer having a circuit formed on its surface into chips with a diamond cutter. When the semiconductor wafer is thinned to about 50 μm, there is a high risk that the semiconductor wafer will be damaged in the grinding process or the dicing process among the IC chip manufacturing processes.

The reinforced semiconductor wafer thin film has a storage elastic modulus E '(Pa) measured using a viscoelasticity measuring apparatus under the conditions of a frequency of 10 Hz and a strain of 0.1%, and a storage elastic modulus E' (Pa) of 5 Pa / ° C. or more at the first phase transition temperature. It is reinforced by a support layer made of a thermosoftening resin that changes in proportion. Such a reinforced semiconductor wafer thin film is also one aspect of the present invention.
By using such a support plate, the reinforcing semiconductor wafer thin film is less likely to be damaged even in the grinding process or the dicing process at a predetermined temperature or lower, and the yield can be improved. It softens rapidly and can be easily peeled off from the semiconductor wafer thin film while turning. When a general thermoplastic resin that is hard at room temperature is used, the storage elastic modulus E'at the first phase transition temperature is
The change in (Pa) is small, and it is necessary to give a large temperature change in order to obtain the above-mentioned effect, which may make it difficult to control the process or cause the wafer to be distorted due to the rapid temperature change. . The method of the present invention is excellent in this respect. The more rapidly the storage elastic modulus E ′ of the thermosoftening resin changes, the more preferable, and the storage elastic modulus E ′ (Pa) more preferably changes at a ratio of 10 Pa / ° C. or more at the first phase transition temperature. As used herein, the first-order phase transition temperature means a temperature at which a specific portion of a polymer, which is initially aligned in an ordered arrangement, becomes a disordered state by a certain equilibrium process.

The thickness of the semiconductor wafer applied to the present invention is not particularly limited, but the thinner the semiconductor wafer is, the more easily the effect of preventing damage is exhibited, and the thickness of the semiconductor wafer is about 50 μm, for example, 20 to 80 μm. In this case, an excellent effect of preventing damage is exhibited. In the grinding process,
Since the back surface of the wafer is ground, the surface of the semiconductor wafer which is in contact with the adhesive layer is limited to the front surface of the semiconductor wafer on which the circuit is formed. In the dicing step, the surface of the semiconductor wafer which is in contact with the adhesive layer may be the surface on which the circuit is formed or the surface on which the circuit is not formed.

A crystallizable polymer is preferably used as the thermosoftening resin whose storage elastic modulus E '(Pa) decreases by the heating at a rate of 5 Pa / ° C or more. Examples of the crystallizable polymer include a side chain crystallizable polymer and a main chain crystallizable polymer. The side-chain crystallizable polymer contains a crystallizable side-chain portion, and the main-chain crystallizable polymer can be crystallized due to its skeletal structure.

Examples of the side-chain crystallizable polymer include linear aliphatic acrylates having 14 to 50 carbon atoms, linear aliphatic methacrylates having 14 to 50 carbon atoms, and 1 carbon atom.
4 to 50 linear aliphatic acrylamide and 14 carbon atoms
.About.50 linear aliphatic methacrylamides and the like.
Among them, a linear aliphatic acrylate having 16 to 22 carbon atoms, a linear aliphatic methacrylate having 16 to 22 carbon atoms, a linear aliphatic acrylamide having 16 to 22 carbon atoms, and a linear aliphatic having 16 to 22 carbon atoms Polymers containing methacrylamide as a main component are preferable.

Storage elastic modulus E '(P
The temperature at which a) changes rapidly can be appropriately changed by changing the structure of the polymer, the formulation of the composition and the like. Table 1 shows the temperatures at which the storage elastic modulus E '(Pa) of the side chain crystallizable polymer mainly containing acrylate or methacrylate having a linear alkyl group as a side chain changes rapidly.

[0015]

[Table 1]

As the crystallizable polymer, a main chain crystallizable polymer which can be crystallized by the respective main chain structure may be used. As the main chain crystallizable polymer, for example, water-insoluble polyalkylene oxide, lower alkyl polyester, polyamide, nylon, polytetrahydrofuran, etc. are preferably used. Among them, a poly-α-olefin polymer having a repeating unit represented by the following general formula is preferable. _{[-CH 2 -CH (R) -} ] Formula, R represents hydrogen or a linear or branched alkyl having a carbon number of 1 to 12, more preferably an alkyl linear or branched having 1-8 carbon atoms And specifically includes, for example, hydrogen, methyl, propyl, butyl, pentyl, 4-methylpentyl, hexyl and heptyl.

Preferable examples of the above polymer include, for example,
(1) 20 to 50 parts by weight of stearyl acrylate, 50 to 80 parts by weight of hexadodecyl acrylate, 2 to 10 parts by weight of acrylic acid and 5-1 to dodecyl mercaptan
5 parts by weight of copolymer; (2) docosyl acrylate 40
-70 parts by weight, 30-50 parts by weight of stearyl acrylate, 1-5 parts by weight of acrylic acid and 5-15 parts by weight of dodecyl mercaptan; (3) 70-95 parts by weight of docosyl acrylate, 3-10 parts of acrylic acid. And a copolymer of 5 to 15 parts by weight of dodecyl mercaptan and the like.

In the method for producing an IC chip of the present invention, the temperature at which the storage elastic modulus E '(Pa) of the thermosoftening resin changes rapidly is preferably 40 to 100 ° C. If the temperature is lower than 40 ° C, the temperature of the support plate may rise during the process and the supporting plate may come off, and if the temperature exceeds 100 ° C, the grinding tape or the dicing tape may shrink. More preferably, it is 50 to 80 ° C. When a thermoplastic resin that is hard at ordinary temperature is used, it is necessary to heat it to 100 ° C. or more in order to sufficiently soften it.
Also in this respect, the method of the present invention is excellent. Therefore, as the thermosoftening resin, a side-chain crystallizable resin containing an acrylic acid ester and / or a methacrylic acid ester whose main chain is a linear alkyl group having 14 or more carbon atoms as a main component is preferable. Used. More preferably, it is a side-chain crystallizable resin containing an acrylic acid ester and / or a methacrylic acid ester having a side chain of a linear alkyl group having 20 or more carbon atoms as a main component.

The above-mentioned thermosoftening resin preferably has a molecular weight of 500,000 or more. When it is less than 500,000, the cohesive force of the resin is low, and when the support is peeled from the wafer, it may remain glued.

The above-mentioned thermosoftening resin may be used as a composition in which it is mixed with another resin so as to have tackiness and flexibility as long as its properties are not impaired. The other resin is not particularly limited, and examples thereof include acrylates such as butyl acrylate; natural rubber adhesives; styrene / butadiene latex base adhesives; ABA block copolymer type thermoplastic rubbers (A is a thermoplastic polystyrene terminal). Block, B represents a polyisoprene, polybutadiene or poly (ethylene / butylene) rubber intermediate block); butyl rubber; polyisobutylene; polyacrylate; and acrylic adhesive such as vinyl acetate / acrylic ester copolymer; polyvinyl methyl ether,
Examples thereof include copolymers of polyvinyl ether such as polyvinyl ethyl ether and polyvinyl isobutyl ether.

The above-mentioned thermosoftening resin may be crosslinked as long as its properties are not impaired. By being cross-linked, the cohesive force of the resin is increased and the residue of glue is further reduced. The method for crosslinking the thermosoftening resin is not particularly limited, and a commonly used method can be used.

In addition to the above components, the above-mentioned thermosoftening resin is optionally compounded with a general pressure-sensitive adhesive such as an isocyanate compound, a melamine compound, an epoxy compound or the like for the purpose of adjusting the cohesive force as a pressure-sensitive adhesive. You may mix | blend various polyfunctional compounds suitably. Further, known additives such as a plasticizer, a resin, a surfactant, a wax and a fine particle filler can be added.

The support plate may be formed by laminating the thermosoftening resin on a base material. Due to the presence of the base material, when the support plate is peeled off from the semiconductor wafer thin film, even if the strength of the thermosoftening resin is lost by heating, the support layer can be easily peeled off by pulling the base material portion. The base material is not particularly limited, and examples thereof include acrylic, olefin, polycarbonate, vinyl chloride, ABS, PE.
Examples include sheets made of T, nylon, urethane, polyimide, metal foil, glass fiber, carbon fiber and the like. Further, when the thermosoftening resin layer is thin and cannot be sufficiently reinforced by itself, the reinforcing effect can be obtained by the base material. In this case, it is preferable that the base material has both hardness for achieving a sufficient reinforcing effect and flexibility for peeling off the support plate when peeling the support plate from the semiconductor wafer thin film. Examples of such a base material include a carbon fiber sheet and a sheet prepared by adjusting the above materials to an appropriate thickness.

The adhesion between the support plate and the semiconductor wafer thin film is achieved by the adhesive force of the thermosoftening resin itself. The thermosoftening resin softens once it is heated to a predetermined temperature or higher, and develops an adhesive force, so that it can be bonded to a semiconductor wafer thin film by the adhesive force. Further, when the thermosoftening resin is used as a composition with another resin having adhesiveness, it can be bonded even at room temperature. The above-mentioned heat-softenable resin softens and develops an adhesive force at least when heated, but may have an adhesive force at room temperature.

In the present invention, in the grinding step and / or the dicing step, the reinforcing semiconductor wafer thin film is processed while being attached to the grinding tape or the dicing tape. The state in which the reinforcing semiconductor wafer thin film is attached to the grinding tape or the dicing tape may be a mode in which the support plate is in contact with the grinding tape or the dicing tape, and the semiconductor wafer is the grinding tape or the dicing tape. It may be in contact with each other. However,
It is preferable that the support plate is in contact with the grinding tape when the back surface of the semiconductor wafer is ground. The grinding tape or the dicing tape is not particularly limited, but a known photocurable adhesive tape can be used, for example,
Furukawa Electric Co., Ltd. Adwill (registered trademark) D-series, Nitto Denko Corp., ELEP holder (registered trademark) UE
Examples include tapes from series. Known heat-foamable pressure-sensitive adhesive tapes are also used, and examples thereof include Riva Alpha (registered trademark) manufactured by Nitto Denko Corporation.

In the method of manufacturing an IC chip of the present invention, first, the reinforcing semiconductor wafer thin film is diced to obtain a reinforcing semiconductor wafer small piece having a supporting plate attached to the IC chip. Such a reinforced semiconductor wafer piece is also one aspect of the present invention. The size of the above-mentioned reinforced semiconductor wafer piece is usually 100 μm to several tens of mm on one side.
Is. After the small pieces of the reinforcing semiconductor wafer are fixed on the substrate from the semiconductor wafer side, the supporting plate is rapidly softened by heating, and the IC chip can be easily peeled off.
A conductive connection structure is obtained. A method of manufacturing such a conductive connection structure is also one aspect of the present invention.

Examples of the substrate include a printed wiring board based on paper phenol resin, glass epoxy resin, glass polyimide resin and the like, flexible printed wiring board made of polyimide, saturated polyester resin and the like, a ceramic substrate and the like. The structure of the substrate may be a single-layer structure or a multi-layer structure. It may also be laminated on another chip.

Wirings made of materials such as gold, silver, copper, aluminum and carbon are provided on the substrate.
An electrode portion is formed at a specific position of this wiring. The electrode part is formed at a position corresponding to the electrode part of the electronic component element or another substrate connected to the electrode part.

The method of connecting the substrate and the IC chip is not particularly limited, and examples thereof include bonding, soldering, conductive fine particles, and anisotropic conductive film.

[0030]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

(Example 1) <Preparation of support plate> A viscoelasticity measuring device at a primary phase transition temperature of 60 ° C or higher was obtained by irradiating a mixture obtained by mixing the following compounds while heating at 70 ° C with ultraviolet rays to solidify the mixture. A sheet-like support plate having a thickness of 1 mm and made of a thermosoftening resin whose storage elastic modulus E '(Pa) measured at a frequency of 10 Hz and a strain of 0.1% is reduced at a rate of 10 Pa / ° C. It was Behenyl acrylate 70 parts by weight Butyl acrylate 30 parts by weight Acrylic acid 1 part by weight Hexanediol diacrylate 0.1 parts by weight Photopolymerization initiator 1 part by weight (Ciba Specialty Chemicals, Irgacure 651)

<Production of Reinforced Semiconductor Wafer Thin Film and IC Chip> A support plate is heated to 80 ° C. to soften it to develop an adhesive force, and a silicon wafer having a thickness of 50 μm is attached, and then cooled to room temperature. By doing so, a reinforced semiconductor wafer was produced. The reinforced semiconductor wafer thus obtained could be handled satisfactorily without being damaged even when the back surface was ground in the grinding step or processed into small pieces of the semiconductor wafer in the dicing step. After the grinding process or the dicing process was finished, the support plate was rapidly softened by being heated to 80 ° C. so that the support plate could be easily removed from the semiconductor wafer or the IC chip.

After the small pieces of the reinforced semiconductor wafer are adhered to the circuit board, the support plate is heated to 80 ° C. and then removed, and the IC chip and the circuit board are connected by wiring to produce a conductive connection structure. did. Here, the reinforced semiconductor wafer piece was excellent in handleability without being damaged. (Example 2) <Preparation of support layer> A mixture obtained by mixing the following compounds while heating at 70 ° C was cast on the corona-treated surface of a polyethylene terephthalate (PET) sheet having one surface corona-treated, and then UV rays were applied. By irradiating and solidifying
A thermosoftening resin whose storage elastic modulus E ′ (Pa) measured at a frequency of 10 Hz and a strain of 0.1% at a primary phase transition temperature of 60 ° C. or higher using a viscoelasticity measuring device decreases at a rate of 10 Pa / ° C. A support plate having a thickness of 30 μm and laminated on the PET sheet was obtained. Behenyl acrylate 70 parts by weight Butyl acrylate 30 parts by weight Acrylic acid 1 part by weight Hexanediol diacrylate 0.1 parts by weight Photopolymerization initiator 1 part by weight (Ciba Specialty Chemicals, Irgacure 651)

<Production of Reinforced Semiconductor Wafer Thin Film and IC Chip> A support plate is heated to 80 ° C. to soften the thermosoftening resin layer to develop adhesiveness, and a silicon wafer having a thickness of 50 μm is attached. After that, it was cooled to room temperature to prepare a reinforced semiconductor wafer. The reinforced semiconductor wafer thus obtained could be handled satisfactorily without being damaged even when the back surface was ground in the grinding step or processed into small pieces of the semiconductor wafer in the dicing step. 80 ° C after the grinding process or the dicing process
When heated to a high temperature, the thermosoftening resin layer of the support plate rapidly softens and loses its adhesive strength, and the PET sheet also had sufficient flexibility. The supporting plate could be easily removed from the chip.

After the small pieces of the reinforced semiconductor wafer are adhered to the circuit board, the support plate is heated to 80 ° C. and then removed, and the IC chip and the circuit board are connected by wiring to form a conductive connection structure. did. Here, the reinforced semiconductor wafer piece was excellent in handleability without being damaged.

[0036]

Since the present invention has the above-mentioned structure,
To provide an IC chip manufacturing method capable of preventing breakage of a semiconductor wafer, improving the handling property, and favorably processing into an IC chip even when processing a semiconductor wafer having a thickness of about 0 μm. You can

Claims (8)

[Claims] 1. A method for manufacturing an IC chip, comprising processing a semiconductor wafer with a reinforcing semiconductor wafer thin film adhered to a grinding tape or a dicing tape in at least a grinding step or a dicing step. Uses a viscoelasticity measuring device and has a frequency of 10 Hz,
Storage modulus E '(P
A method of manufacturing an IC chip, wherein a) is reinforced by a support layer made of a thermosoftening resin that changes at a rate of 5 Pa / ° C. or more at the first phase transition temperature. 2. A thermosoftening resin is an acrylic ester having a side chain of a linear alkyl group having 14 or more carbon atoms and /
2. A method of manufacturing an IC chip according to claim 1, wherein the resin is a side chain crystallizable resin containing methacrylic acid ester as a main component. 3. The method of manufacturing an IC chip according to claim 1, wherein the thermosoftening resin has a molecular weight of 500,000 or more. 4. A semiconductor wafer has a storage elastic modulus E ′ (Pa) measured using a viscoelasticity measuring apparatus under the conditions of a frequency of 10 Hz and a strain of 0.1%, and a storage elastic modulus E ′ (Pa) of 5 Pa at a first-order phase transition temperature.
A reinforced semiconductor wafer thin film, which is reinforced by a support plate made of a thermosoftening resin that changes at a rate of / ° C or higher. 5. A thermosoftening resin is an acrylate ester having a linear alkyl group having 14 or more carbon atoms as a side chain, and /
5. A reinforced semiconductor wafer thin film according to claim 4, which is a side-chain crystallizable resin containing methacrylic acid ester as a main component. 6. The reinforced semiconductor wafer thin film according to claim 4 or 5, wherein the thermosoftening resin has a molecular weight of 500,000 or less. 7. A small piece of a reinforced semiconductor wafer obtained by dicing the reinforced semiconductor wafer thin film according to claim 4, 5, or 6. 8. The small piece of the reinforced semiconductor wafer according to claim 7 is fixed on the substrate from the semiconductor wafer side and then heated to soften the thermosoftening resin to separate the IC chip from the support plate. Method for manufacturing a conductive connection structure.