JP6733394B2 - Adhesive sheet and method for manufacturing semiconductor device. - Google Patents

Description

The present invention relates to an adhesive sheet and a method for manufacturing a semiconductor device.

Conventionally, a silver paste is mainly used for joining a semiconductor element and a semiconductor element mounting wiring board. However, with the recent miniaturization and high performance of semiconductor elements, miniaturization and miniaturization of wiring boards used have also been required. In the case of joining using a silver paste, the above-mentioned requirements are caused by the occurrence of defects during wire bonding due to the protrusion of the silver paste and the inclination of the semiconductor element, the difficulty in controlling the thickness of the adhesive layer, the occurrence of voids in the adhesive layer, etc. Can't cope with. Therefore, in recent years, a film adhesive (adhesive film) has been used for joining the semiconductor element and the semiconductor element mounting wiring board (see, for example, Patent Documents 1 and 2).

Generally, the mounting substrate manufacturing process is performed as follows. First, one surface of the adhesive film is attached to the dicing tape, and the other surface of the adhesive film is attached to the back surface of the semiconductor wafer. Then, in a dicing step, the semiconductor wafer to which the adhesive film is attached is separated into semiconductor elements with an adhesive film. Next, in a die bonding step (also referred to as a die attach step), the individual semiconductor elements with an adhesive film are picked up and bonded to a wiring board. Then, in order to prevent the semiconductor element bonded to the wiring board from being peeled off or removed during transportation, curing is performed in an oven for a short time. After that, a mounting substrate is manufactured by undergoing a wire bonding step, a sealing step, a sealing material curing step, and a reflow step for solder ball attachment.

Reliability is one of the most important characteristics of a mounting board on which various electronic components such as semiconductor elements are mounted. In order to improve the reliability of the manufactured semiconductor device, development of a film adhesive in which heat resistance, moisture resistance and reflow resistance are taken into consideration is under development. As such a film adhesive, for example, Patent Document 3 proposes an adhesive film containing an epoxy resin, a phenol resin, and an acrylic copolymer.

JP-A-3-192178 JP-A-4-234472 JP, 2002-220576, A

In recent years, miniaturization and high integration of semiconductor packages have been advanced. In order to stack semiconductor elements in multiple stages, it is necessary to repeatedly perform a die bonding process and a wire bonding process in manufacturing a mounting board. The conventional adhesive sheet is repeatedly heated in these steps, so that curing progresses and the elastic modulus is increased. If the elastic modulus of the adhesive sheet is increased, it becomes difficult to fill the irregularities on the substrate in the sealing step. Therefore, if a mounting board is manufactured using a conventional adhesive sheet, the reliability of the mounting board obtained may be lowered. Therefore, even if it is repeatedly heated in the die bonding process and the wire bonding process, it is possible to fill the unevenness on the substrate in the encapsulation process with excellent heat history and to obtain an adhesive sheet with a low elastic modulus and a high adhesive strength. Development is in progress.

On the other hand, as the degree of integration of semiconductor packages increases, it is expected that not only the thinning of the semiconductor element used but also the thinning of the adhesive sheet will be required. When a thin adhesive sheet having a low elastic modulus is used for manufacturing the mounting substrate, physical stress is concentrated on the chip (semiconductor chip) in the wire bonding process, and the chip may be cracked.

Furthermore, in recent years, in the above-described mounting board manufacturing process, further improvement in throughput is desired in order to reduce the production cost. In order to improve the throughput in manufacturing the mounting substrate, it is desirable to shorten the curing process after the die bonding process. However, when the conventional adhesive sheet is used, if the curing step is shortened, the adhesive strength to the substrate becomes insufficient, and in the sealing step, the encapsulant may penetrate between the substrate and the adhesive layer. ..

The present invention has been made in view of the above problems of the prior art. Even when the curing step is shortened or omitted, the encapsulating material penetrates between the chip and the substrate (or between the chip and the chip) in the encapsulating step. Sufficient adhesive strength that can suppress the, even when formed into a thin film, has a sufficient storage elastic modulus that can suppress the cracking of the chip in the wire bonding process, further, by having an excellent heat history, sealing An object of the present invention is to provide an adhesive sheet capable of exhibiting excellent irregularity embedding property with respect to irregularities on a substrate in a process, and a semiconductor device manufacturing method using the same.

In order to achieve the above object, the present invention provides an adhesive composition containing an epoxy resin, an epoxy resin curing agent, an epoxy group-containing (meth)acrylic copolymer, and an imine silane coupling agent. Provided is an adhesive sheet including a sheet-shaped adhesive layer.

An adhesive sheet according to one aspect of the present invention is a sheet-like adhesive composition containing an epoxy resin, an epoxy resin curing agent, an epoxy group-containing (meth)acrylic copolymer, and an imine-based silane coupling agent. By providing the adhesive layer formed in, the adhesion to the substrate is improved, and immediately after the die bonding step, with the heat and pressure in the die bonding step, the adhesive strength capable of withstanding the encapsulation of the sealing material in the sealing step is provided. It is possible. Further, the adhesive sheet has a sufficient storage elastic modulus that can suppress cracking of the chip in the wire bonding process even when it is formed into a thin film. Furthermore, the adhesive sheet does not excessively accelerate the curing reaction of the adhesive layer due to the heat generated in the die bonding step and the wire bonding step, and the adhesive sheet is bonded even if it is repeatedly heated in the die bonding step and the wire bonding step. It is possible to prevent the storage elastic modulus of the agent layer from rising excessively. As described above, since the adhesive sheet has excellent heat resistance history, it can exhibit excellent unevenness embedding property with respect to unevenness on the substrate in the sealing step performed after the die bonding step and the wire bonding step. it can.

The imine-based silane coupling agent preferably contains an imine-based silane coupling agent represented by the following general formula (3).

［式中、Ｒ^１は２価の炭化水素基を示し、Ｒ^２及びＲ^３はそれぞれ独立に水素原子又は１価の炭化水素基を示し、Ｒ^４はアルキル基を示す。］

[In the formula, R ¹ represents a divalent hydrocarbon group, R ² and R ³ each independently represent a hydrogen atom or a monovalent hydrocarbon group, and R ⁴ represents an alkyl group. ]

By using the imine-based silane coupling agent represented by the general formula (3), it is possible to further improve the adhesive strength between the chip and the substrate or between the chip and the chip, and when the adhesive layer is a thin film. However, cracking of the chip in the wire bonding process can be suppressed more sufficiently.

The content of the imine-based silane coupling agent in the adhesive composition is preferably 0.5 to 5 mass% based on the total solid content of the adhesive composition.

When the content of the imine-based silane coupling agent is 0.5% by mass or more, the effect of suppressing penetration of the encapsulant in the encapsulation step and the effect of suppressing chip cracks (die cracks) in the wire bonding step are further improved. .. When the content of the imine-based silane coupling agent is 5% by mass or less, the embedding property of irregularities on the substrate in the sealing step becomes better.

The epoxy group-containing (meth)acrylic copolymer is preferably a copolymer having a glass transition temperature of −50 to 30° C. and a weight average molecular weight of 100,000 or more.

When the glass transition temperature of the epoxy group-containing (meth)acrylic copolymer is -50°C or higher, the dicing property is better maintained. When the glass transition temperature is 30° C. or lower, voids can be better filled in when the adhesive layer is attached to the wafer and in the sealing step. Further, when the glass transition temperature is 30° C. or lower, chipping during dicing is further reduced. When the weight average molecular weight is within the above range, the strength, flexibility and tackiness of the adhesive layer can be controlled appropriately. Further, when the weight average molecular weight is within the above range, the reflow property of the adhesive layer and the embeddability of irregularities on the substrate are further improved.

In the adhesive composition, the ratio of the total mass of the epoxy resin and the epoxy resin curing agent to the mass of the epoxy group-containing (meth)acrylic copolymer is 0.05 to 0.50. preferable.

When the ratio of the total mass of the epoxy resin and the epoxy resin curing agent to the mass of the epoxy group-containing (meth)acrylic copolymer is within the above range, control of fluidity during molding of the adhesive layer and handling at high temperature Also, the embeddability of the irregularities on the substrate can be further improved.

The adhesive composition further comprises an inorganic filler having an average particle size of 0.005 to 0.5 μm in an amount of 1 to 100 parts by mass based on the total solid content of the adhesive composition excluding the inorganic filler. It is preferable to contain 50 parts by mass.

The adhesive sheet according to one embodiment of the present invention, in which the adhesive composition further contains an inorganic filler, is sufficiently excellent in adhesive strength, embedding of irregularities on a substrate, and insulating properties, and reliability of a semiconductor device to be manufactured. Can be further improved.

The thickness of the adhesive layer may be 3 to 30 μm. When the thickness is in the above range, the embedding property of the irregularities on the substrate is sufficiently exhibited. Further, when the thickness is in the above range, it is advantageous for high integration of the semiconductor package.

The storage elastic modulus of the adhesive layer at a temperature of 150° C. may be 3 to 20 MPa. When the storage elastic modulus is in the above range, the effect of suppressing chip cracks in the wire bonding process is further improved, and the embedding property of irregularities on the substrate in the sealing process is more improved.

A method for manufacturing a semiconductor device according to an aspect of the present invention, a semiconductor element and a supporting member, a die bonding step of thermocompression bonding through the adhesive layer in an adhesive sheet, the semiconductor element and the supporting member, The method includes a wire bonding step of electrically connecting with a wire while heating, and a sealing step of sealing the semiconductor element with a resin.

According to the present invention, even when the curing step is shortened or omitted, the thin film has sufficient adhesive strength capable of suppressing the infiltration of the encapsulating material between the chip and the substrate (or between the chip and the chip) in the encapsulating step. Even if it is set to, even if it has a sufficient storage elastic modulus that can suppress the cracking of the chip in the wire bonding process, and also has an excellent heat resistance history, excellent embedding property for the unevenness on the substrate in the sealing process It is possible to provide an adhesive sheet capable of exhibiting the above and a method for manufacturing a semiconductor device using the same.

It is a schematic cross section which shows one suitable embodiment of the adhesive sheet of this invention. It is a schematic cross section which shows one suitable embodiment of the semiconductor device of this invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings in some cases. In the drawings, the same or corresponding parts will be denoted by the same reference symbols, without redundant description. Note that the dimensional ratios in the drawings are exaggerated for the sake of explanation, and do not necessarily match the actual dimensional ratios.

An adhesive sheet according to an embodiment of the present invention is a sheet-like adhesive composition containing an epoxy resin, an epoxy resin curing agent, an epoxy group-containing (meth)acrylic copolymer, and an imine-based silane coupling agent. An adhesive sheet comprising the adhesive layer formed in 1.

First, each component which comprises the adhesive composition which concerns on this embodiment is demonstrated in detail. In addition, in this specification, (meth)acryl means acryl or methacryl.

(Epoxy resin)
The epoxy resin according to this embodiment is not particularly limited as long as it has at least two epoxy groups in the molecule. Examples of the epoxy resin include bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin and other novolac type epoxy resins, and many Functional epoxy resins and cycloaliphatic epoxy resins may be mentioned. These may be used alone or in combination of two or more.

Since the epoxy resin, which is a thermosetting resin, is cured by heat during the die bonding process and the wire bonding process, the epoxy resin acts to further improve the adhesive strength and the storage elastic modulus of the adhesive layer.

(Epoxy resin curing agent)
As the epoxy resin curing agent according to this embodiment, a phenolic epoxy resin curing agent can be used. The epoxy resin curing agent may be used alone or in combination of two or more.

From the viewpoint of the curability of the adhesive layer, the mixing ratio of the epoxy resin and the phenol-based epoxy resin curing agent is such that the ratio of the epoxy equivalent of the epoxy resin and the hydroxyl equivalent of the phenol-based epoxy resin curing agent is 0.70/0. It is preferably set in the range of 0.30 to 0.30/0.70, more preferably 0.65/0.35 to 0.35/0.65, and further preferably 0.60/0.40. ˜0.40/0.60, particularly preferably 0.55/0.45 to 0.45/0.55.

(Epoxy group-containing (meth)acrylic copolymer)
The epoxy group-containing (meth)acrylic copolymer according to the present embodiment can be obtained by polymerizing a monomer containing a functional monomer such as glycidyl acrylate or glycidyl methacrylate. Since the functional monomer is incompatible with the epoxy resin, the epoxy resin and the (meth)acrylic copolymer are separated from each other after curing, and the reflow crack resistance and heat resistance of the adhesive layer can be improved. ..

As the (meth)acrylic copolymer, for example, (meth)acrylic acid ester copolymer, acrylic rubber and the like can be used, and acrylic rubber is more preferable. Acrylic rubber is a rubber mainly composed of an acrylic ester and mainly composed of a copolymer such as butyl acrylate and acrylonitrile, or a copolymer such as ethyl acrylate and acrylonitrile.

That is, as the epoxy group-containing (meth)acrylic copolymer, a copolymer of a functional monomer such as glycidyl acrylate or glycidyl methacrylate and butyl acrylate, ethyl acrylate, acrylonitrile or the like can be used. The method for polymerizing the epoxy group-containing (meth)acrylic copolymer is not particularly limited, and pearl polymerization, solution polymerization and the like can be used.

From the viewpoint of ensuring both adhesive strength and gelation prevention of the adhesive layer, the structural unit derived from the epoxy group-containing monomer in the epoxy group-containing (meth)acrylic copolymer is 0.5 to 3 The content is preferably 0.0% by mass, more preferably 2.0 to 3.0% by mass, and further preferably 2.0 to 2.7% by mass.

The epoxy group-containing (meth)acrylic copolymer is available as a commercial product, and for example, the trade name “HTR-860P-3CSP” manufactured by Nagase Chemtech Co., Ltd. can be used.

The glass transition temperature (Tg) of the epoxy group-containing (meth)acrylic copolymer is preferably -50 to 30°C, more preferably -30 to 30°C. When the Tg of the epoxy group-containing (meth)acrylic copolymer is -50°C or higher, the flexibility of the adhesive layer does not become too high, so that the adhesive layer can be more easily cut during wafer dicing. As a result, the occurrence of burrs is reduced and the dicing property is better maintained. Moreover, when Tg is +30° C. or less, the flexibility of the adhesive layer tends to increase. As a result, voids can be better filled in when the adhesive layer is attached to the wafer and during the sealing process. Further, when Tg is +30° C. or less, the adhesion to the wafer is increased, and chipping during dicing is further reduced.

In the present specification, the glass transition temperature Tg is measured using a differential scanning calorimeter (DSC).

The weight average molecular weight (Mw) of the epoxy group-containing (meth)acrylic copolymer is preferably 100,000 or more, more preferably 100,000 to 3,000,000, and further preferably 500,000 to 2,000,000. preferable. When the Mw of the epoxy group-containing (meth)acrylic copolymer is within this range, the film, the strength in the film, the flexibility, and the tackiness can be appropriately controlled, and the reflow property is excellent, and the substrate It is possible to improve the embeddability of the upper irregularities. Here, Mw means a value measured by gel permeation chromatography (GPC) and converted using a calibration curve based on standard polystyrene.

The compounding amount of the epoxy group-containing (meth)acrylic copolymer is preferably 250 to 2000 parts by mass, and preferably 300 to 1500 parts by mass, based on 100 parts by mass of the total of the epoxy resin and the epoxy resin curing agent. More preferable. The ratio A/B of the total mass A of the epoxy resin and the epoxy resin curing agent to the mass B of the epoxy group-containing (meth)acrylic copolymer is preferably 0.05 to 0.50, and 0.07 to It is more preferably 0.40, and even more preferably 0.10 to 0.30. When the ratio A/B of the total mass A of the epoxy resin and the epoxy resin curing agent to the mass B of the epoxy group-containing (meth)acrylic copolymer is within this range, control of fluidity during molding of the adhesive layer, It is possible to further improve the handling property at high temperature and the embedding property of irregularities on the substrate.

Since the epoxy group-containing (meth)acrylic copolymer is thermoplastic and has a glass transition temperature sufficiently lower than the temperature in the sealing step, it acts to improve the embeddability of irregularities on the substrate. To do. Further, by including the epoxy group-containing (meth)acrylic copolymer, it is possible to prevent the storage elastic modulus of the adhesive layer from becoming excessively high due to thermal history.

The content of the epoxy group-containing (meth)acrylic copolymer in the total solid content of the adhesive composition is preferably 45 to 70% by mass, more preferably 55 to 60% by mass. When the content of the epoxy group-containing (meth)acrylic copolymer is at least the above lower limit, the embeddability of irregularities on the substrate in the sealing step will be further improved. When the content of the epoxy group-containing (meth)acrylic copolymer is less than or equal to the above upper limit, the adhesive strength of the adhesive layer is more favorably maintained, and the effect of suppressing penetration of the encapsulant in the encapsulation process is further improved. To do. When the content of the epoxy group-containing (meth)acrylic copolymer is less than or equal to the above upper limit, the storage elastic modulus of the adhesive layer is appropriately improved, and chip cracking in the wire bonding step is further reduced.

In the present specification, the solid content means a non-volatile component at room temperature and atmospheric pressure, and includes liquid, starch syrup and wax at room temperature and atmospheric pressure. Therefore, the total solid content of the adhesive composition means the amount obtained by subtracting the amount of the volatile component (solvent) from the total amount of the adhesive composition.

(Imine silane coupling agent)
The adhesive composition according to this embodiment contains an imine-based silane coupling agent. In the present specification, the imine-based silane coupling agent means a silane coupling agent having a partial structure represented by the following general formula (1).

In formula (1), R ¹ represents a divalent hydrocarbon group, and R ² and R ³ each independently represent a hydrogen atom or a monovalent hydrocarbon group.

As the imine-based silane coupling agent, for example, an imine-based silane coupling agent represented by the following general formula (2) can be used.

In the formula (2), x is 2 or 3. R ¹ represents a divalent hydrocarbon group, and is preferably a methylene group. When R ¹ has a small number of carbon atoms, —Si(OR ⁴ ) _x (R ⁵ ) _3-x is closer to the nitrogen atom, and thus the reactivity of the nitrogen atom is further suppressed by steric hindrance. R ² and R ³ each independently represent a hydrogen atom or a monovalent hydrocarbon group, and preferably a monovalent hydrocarbon group. Among the monovalent hydrocarbon groups, an allyl group, a tertiary alkyl group, or a secondary alkyl group is more preferable, an allyl group or a tertiary alkyl group is more preferable, and an allyl group. Is particularly preferable. When R ² or R ³ is a high substituent, the reactivity of the nitrogen atom is further suppressed due to steric hindrance. When R ² or R ³ is an allyl group, the unshared electron pair on the nitrogen atom is resonance-stabilized, so that the reactivity of the nitrogen atom is further suppressed. R ⁴ and R ⁵ each independently represent an alkyl group. By suppressing the reactivity of the nitrogen atom, the excessive curing of the epoxy resin by the imine-based silane coupling agent can be further suppressed. By suppressing the excessive curing of the epoxy resin, the embedding property for the irregularities on the substrate in the sealing step can be better maintained. The imine-based silane coupling agent may be used alone or in combination of two or more.

As the imine-based silane coupling agent, more specifically, an imine-based silane coupling agent represented by the following general formula (3) can be used.

In formula (3), R ¹ , R ² , R ³ , and R ⁴ have the same meanings as in formula (2).

Specific examples of the imine-based silane coupling agent include 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine represented by the following formula (4) and N-3-(isomaleimide)- Examples include propyltriethoxysilane, and 3-(triethoxysilyl)-1-propylamino-N-styrene.

The imine-based silane coupling agent is commercially available, and for example, the trade name “KBE-9103” manufactured by Shin-Etsu Chemical Co., Ltd. can be preferably used.

The content of the imine-based silane coupling agent in the adhesive composition is preferably 0.1 to 10% by mass, and is 0.5 to 5% by mass, based on the total solid content of the adhesive composition. It is more preferable that the amount is 1 to 2.5% by mass. When the content of the imine-based silane coupling agent is at least the above lower limit value, the adhesive strength of the adhesive layer is further improved, and the effect of suppressing the penetration of the sealing material in the sealing step is further improved. Further, when the content of the imine-based silane coupling agent is at least the above lower limit value, the storage elastic modulus of the adhesive layer is improved, and the effect of suppressing chip cracking in the wire bonding step is further improved. When the content of the imine-based silane coupling agent is at most the above upper limit value, the heat resistance history will be better maintained, and the embedding property of the irregularities on the substrate in the sealing step will be better.

Since the imine-based silane coupling agent has a reactive nitrogen atom, it acts to cure the epoxy resin and further improve the adhesive strength and storage elastic modulus of the adhesive layer. Therefore, even if the curing process is shortened or omitted, sufficient bonding strength can be obtained by heat and pressure in the die bonding process, and chip cracking in the wire bonding process can be suppressed. On the other hand, the imine-based silane coupling agent has a lower reactivity of nitrogen atom than many other amine-based silane coupling agents, and thus does not excessively proceed the curing reaction of the epoxy resin and is stored. It is possible to suppress an excessive increase in elastic modulus.

The adhesive composition may further contain a silane coupling agent other than the imine silane coupling agent, a titanate coupling agent or an aluminum coupling agent. Examples of other silane coupling agents include vinyl-based, epoxy-based, stilyl-based, methacrylic-based, acrylic-based, amino-based, ureido-based, mercapto-based, sulfide-based, or isocyanate-based silane coupling agents. As the other silane coupling agent, one having higher reactivity than the silane coupling agent having the structure of an aromatic amine and lower reactivity than the silane coupling agent having the structure of the secondary amine is used. May be used. However, from the viewpoint of maintaining the heat resistance history of the adhesive layer, the content of the silane coupling agent other than the imine silane coupling agent is 200 with respect to 100 parts by mass of the total of the imine silane coupling agent. The amount is preferably not more than 100 parts by mass, more preferably not more than 100 parts by mass. The silane coupling agent contained in the adhesive composition may be only the imine-based silane coupling agent. When only the imine-based silane coupling agent is contained, even if the curing step is shortened or omitted, more excellent adhesive strength can be obtained, and the storage stability of the adhesive composition is more excellent.

(Inorganic filler)
The adhesive composition of this embodiment can further contain an inorganic filler. Examples of the inorganic filler include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whiskers, boron nitride, and crystals. Examples of the silica include amorphous silica and amorphous silica. These can be used alone or in combination of two or more. From the viewpoint of improving the thermal conductivity of the adhesive layer, it is preferable to contain aluminum oxide, aluminum nitride, boron nitride, crystalline silica or amorphous silica as the inorganic filler. From the viewpoint of adjusting the melt viscosity of the adhesive layer and imparting thixotropic properties to the adhesive composition, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, oxidation It is preferable to contain magnesium, aluminum oxide, crystalline silica or amorphous silica.

From the viewpoint of improving the adhesiveness of the adhesive layer, the average particle size of the inorganic filler is preferably 0.005 to 0.5 μm, more preferably 0.05 to 0.3 μm. In the present specification, the average particle size is measured by a laser diffraction method or the like.

The surface of the inorganic filler is preferably chemically modified from the viewpoint of compatibility with a solvent or a resin component and adhesive strength. Suitable materials for chemically modifying the surface include silane coupling agents. Examples of the functional group of the silane coupling agent include vinyl group, methacryloyl group, cyclic epoxy group, epoxy group, mercapto group, amino group, diamino group, alkoxy group, ethoxy group and the like. Since the surface of the inorganic filler is chemically modified, the adhesive strength of the adhesive layer, the embeddability of irregularities on the substrate, and the insulating property are more sufficiently improved, and the reliability of the semiconductor device to be manufactured is further improved. be able to.

The compounding amount of the inorganic filler is preferably 1 to 50 parts by mass, and more preferably 10 to 45 parts by mass, based on 100 parts by mass of the total solid content of the adhesive composition excluding the inorganic filler. When the blending amount of the inorganic filler is within this range, it is possible to secure more sufficient storage elastic modulus, adhesiveness and electrical characteristics of the adhesive layer.

A curing accelerator can also be added to the adhesive composition of this embodiment. The curing accelerator is not particularly limited, and various imidazoles can be used. Examples of the imidazoles include 2-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole and the like, and these may be used alone or in combination of two or more. Can be used together.

The content of the curing accelerator is preferably 0.04 to 5 parts by mass, more preferably 0.04 to 0.2 parts by mass, based on 100 parts by mass of the total of the epoxy resin and the epoxy resin curing agent. When the amount of the curing accelerator added is within this range, both the curability and the reliability of the adhesive layer can be achieved.

Heretofore, each component in the adhesive composition according to the present embodiment has been described. Hereinafter, the adhesive sheet according to the present embodiment will be described in detail.

The adhesive sheet according to the present embodiment may be composed only of an adhesive layer formed from the above-mentioned adhesive composition in a sheet form, a base film, and an adhesive laminated on the base film. And a layer.

FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the adhesive sheet of the present invention. The adhesive sheet 100 shown in FIG. 1 includes a base film 3 and an adhesive layer 1 provided on the base film 3. The adhesive layer 1 is made of an adhesive composition according to an embodiment of the present invention. In the adhesive sheet 100 according to the present embodiment, the surface of the adhesive layer 1 that is not the base film 3 side may be covered with a protective film.

The base film 3 is not particularly limited, and for example, polytetrafluoroethylene, polyethylene film, polypropylene film, polymethylpentene film, polyethylene terephthalate film, polyimide film, etc. are used.

These films may be subjected to surface treatment such as primer coating, UV treatment, corona discharge treatment, polishing treatment and etching treatment, if necessary. The thickness of the base film 3 is not particularly limited and is appropriately selected depending on the thickness of the adhesive layer 1 and the use of the adhesive sheet 100.

The thickness of the adhesive layer 1 is not particularly limited, but is preferably 3 to 30 μm, more preferably 3 μm or more and less than 25 μm. When the thickness of the adhesive layer is within this range, the embedding property of the irregularities on the wiring board can be sufficiently exhibited and it is economical. The adhesive sheet 100 according to the present embodiment can prevent chip cracking in the wire bonding process even with the thin film having the above thickness. Also, two or more adhesive layers 1 can be attached to each other to obtain a desired thickness.

The storage elastic modulus at a temperature of 150° C. of the adhesive layer 1 may be 1 to 20 MPa or 3 to 20 MPa.

The adhesive sheet 100 according to this embodiment can be manufactured, for example, as follows. First, each component constituting the above-mentioned adhesive composition is mixed or kneaded in a solvent to prepare a varnish, a layer of this varnish is formed on the base material film 3, and dried by heating to produce the adhesive sheet 100. Can be obtained. Alternatively, the base material film 3 may be removed after the varnish layer is dried to obtain an adhesive sheet composed only of the adhesive layer 1.

The solvent used for preparing the varnish is not particularly limited, but considering the volatility at the time of film production, methanol, ethanol, 2-methoxyethanol, 2-butoxyethanol, methyl ethyl ketone, acetone, methyl isobutyl ketone, 2- It is preferable to use a solvent having a relatively low boiling point such as ethoxyethanol, toluene or xylene. Further, a solvent having a relatively high boiling point such as dimethylacetamide, dimethylformamide, N-methylpyrrolidone or cyclohexanone may be added to improve the coating property.

The above-mentioned mixing or kneading can be carried out by appropriately combining an ordinary stirrer, a raker, a three-roller, a ball mill, a bead mill and other dispersing machines. For the production of the varnish when the inorganic filler is added, it is preferable to use a raider, a three-roll mill, a ball mill or a bead mill in consideration of the dispersibility of the inorganic filler. Further, it is possible to shorten the mixing time by mixing the slurry of the inorganic filler and the low molecular weight component in advance and then mixing the high molecular weight component. Furthermore, after forming the varnish, it is possible to remove air bubbles in the varnish by vacuum deaeration or the like. It is desirable to perform vacuum deaeration when manufacturing the thin film adhesive sheet 100.

The adhesive sheet 100 is obtained by applying the prepared varnish on the base material film 3 and heating and drying to form the adhesive layer 1. As a method for applying the varnish to the base film 3, a known method can be used, and examples thereof include a knife coating method, a roll coating method, a spray coating method, a gravure coating method, a bar coating method and a curtain coating method. To be The heating and drying conditions are not particularly limited as long as the solvent used is sufficiently volatilized, but are usually 50 to 200° C. and 0.1 to 90 minutes.

The adhesive sheet 100 of the present embodiment may be used by itself, but is used as a dicing tape-integrated adhesive sheet in which the adhesive layer 1 of the adhesive sheet 100 of the present embodiment is laminated on a conventionally known dicing tape. Can also Examples of the method of laminating the adhesive layer 1 on the dicing tape include printing, and a method of pressing or hot-roll laminating the adhesive sheet 100 prepared in advance on the dicing tape. The hot roll laminating method is preferable in that the dicing tape-integrated adhesive sheet can be continuously produced and the efficiency is high. The film thickness of the dicing tape is not particularly limited and may be appropriately determined based on the knowledge of those skilled in the art depending on the film thickness of the adhesive layer 1 and the application of the dicing tape-integrated adhesive sheet. From the viewpoints of economy and handleability of the sheet, the film thickness of the dicing tape is preferably 60 to 200 μm, more preferably 70 to 170 μm.

The adhesive sheet 100 of the present embodiment has a bonding strength to a substrate capable of withstanding the intrusion of a sealing material during the sealing step and does not require a curing step and is only thermocompression-bonded in the die bonding step. The adhesive layer 1 having a heat history that allows sufficient embedding of irregularities on the substrate is provided, and further has a storage elastic modulus capable of preventing die crack due to physical stress in the wire bonding process. Therefore, by using the adhesive sheet 100 of the present invention, it is possible to manufacture a semiconductor device having improved throughput and sufficiently excellent connection reliability.

Next, the manufacturing method of the semiconductor device according to the embodiment of the present invention will be described by taking the manufacturing method of the semiconductor device 210 shown in FIG. 2 as an example. The method for manufacturing a semiconductor device according to this embodiment includes a die bonding step, a wire bonding step, and a sealing step.

In the die bonding step, the semiconductor element 12 a (first semiconductor element) and the support member 13 are thermocompression bonded via the adhesive layer 1. As the adhesive layer 1, a material obtained by peeling the base film 3 from the adhesive sheet 100 in advance may be used. The support member may be, for example, a substrate having unevenness such as a wiring pattern on the surface. The thermocompression bonding can be performed, for example, at 80 to 140° C. and 0.01 to 0.50 MPa for 1 to 5 seconds. The adhesive layer 1 and the semiconductor element 12a may be attached in advance before thermocompression bonding.

In the conventional method, in order to increase the adhesive strength of the adhesive layer 1, a curing step of heating the adhesive layer 1 at 120 to 150° C. for about 15 to 60 minutes was provided after the die bonding step. The semiconductor device manufacturing method according to the second aspect does not require the above curing step. In addition, in the manufacturing method of this embodiment, you may perform the said hardening process and can make heating time shorter (for example, 5 to 15 minutes).

In the wire bonding step, the semiconductor element 12a and the supporting member 13 are electrically connected by the wire 14 while being heated. The heating can be performed, for example, at 150° C. or lower for 1 hour or less.

When the adhesive layer 1 is a thin film, physical stress is likely to be concentrated on the semiconductor elements 12a and 12b in the wire bonding process, and the semiconductor elements 12a and 12b may be cracked.

Here, when a plurality of semiconductor elements are stacked like the semiconductor device 210, the die bonding step and the wire bonding step can be performed multiple times depending on the number of stacked layers. In the case of the semiconductor device 210, for example, the second wire bonding step can be performed after the first wire bonding step, and then the second wire bonding step can be performed. In the second die bonding step, the semiconductor element 12b (second semiconductor element) and the semiconductor element 12a as the supporting member are thermocompression bonded via the adhesive layer 1. In the second wire bonding step, the semiconductor element 12b and the supporting member 13 are electrically connected by the wire 14 while being heated.

Further, instead of repeating the die bonding step and the wire bonding step, only the die bonding step may be repeated to stack the semiconductor elements, and after all the semiconductor elements have been stacked, the wire bonding step may be collectively performed. it can. In the case of the semiconductor device 210, for example, after the first die bonding step, the second die bonding step is performed without performing the wire bonding step to separate the semiconductor element 12b (second semiconductor element) and the semiconductor element 12a. Then, thermocompression bonding is performed via the adhesive layer 1. After that, a wire bonding process is performed to electrically connect the semiconductor elements 12a and 12b to the support member 13.

After all the semiconductor elements (semiconductor elements 12a and 12b) are stacked and electrically connected to the support member 13, the sealing step can be performed. In the sealing step, the semiconductor elements 12 a, 12 b, the wires 14, and the adhesive layer 1 are sealed with the sealing material 15. The sealing can be performed at 170 to 185° C. and 4.5 to 8 MPa for 60 to 180 seconds.

In general, when the adhesive strength of the adhesive layer is low in the sealing step, the sealing material 15 may penetrate between the support member 13 and the semiconductor element 12a or between the semiconductor elements 12a and 12b. is there. When the heat resistance history of the adhesive layer is low, the adhesive layer is excessively hardened due to the heat of the die bonding step and the wire bonding step that are repeatedly performed, and the storage elastic modulus of the adhesive layer excessively increases. .. If the storage elastic modulus of the adhesive layer is high in the sealing step, the irregularities on the surfaces of the support member 13 and the semiconductor element 12b may not be sufficiently filled with the adhesive layer.

Since the method for manufacturing a semiconductor device according to the present embodiment uses the adhesive layer 1 described above, the adhesive strength of the adhesive layer 1 is improved even when the curing step is not performed after the die bonding step, and It is possible to suppress the intrusion of the sealing material 15 between the semiconductor element 12a and the support member 13 or between the semiconductor element 12a and the semiconductor element 12b. Further, since the storage elastic modulus of the adhesive layer 1 is improved, even if the adhesive layer 1 is a thin film, it is possible to prevent the semiconductor elements 12a and 12b from cracking in the wire bonding process. On the other hand, since the heat resistance history of the adhesive layer 1 is also improved, the storage elastic modulus of the adhesive layer 1 does not rise excessively, and the embedding property of irregularities on the surfaces of the support member 13 and the semiconductor element 12b in the sealing step is improved. Also improves.

Hereinafter, the present invention will be specifically described based on Examples, but the present invention is not limited to the following Examples.

(Example 1)
Each component in the compounding ratio (parts by mass) shown in Table 1 was compounded together with cyclohexanone as a solvent to prepare an adhesive composition. First, as an epoxy group-containing (meth)acrylic copolymer, acrylic rubber (manufactured by Hitachi Chemical Co., Ltd., trade name: KS800H, Mw: 1,000,000, mass ratio of butyl acrylate/ethyl acrylate/acrylonitrile/glycidyl methacrylate: 39.4). /29.3/30.3/3) 100.0 parts by mass, acrylic rubber (manufactured by Nagase Chemtech Co., Ltd., trade name: HTR-860P-3, Mw: 800,000, Tg: 15°C, butyl acrylate/ethyl). Mass ratio of acrylate/acrylonitrile/glycidyl methacrylate: 39.4/29.3/30.3/3) 100.0 parts by mass, cresol novolac type epoxy resin (manufactured by Toto Kasei Co., Ltd., trade name: YDCN) as epoxy resin -700-10, epoxy equivalent: 210) 18.0 parts by mass, as an epoxy resin curing agent, phenol resin (manufactured by Mitsui Chemicals, Inc., trade name: XLC-LL, hydroxyl equivalent: 174) 15.0 parts by mass, imine As a silane coupling agent, 8.5 parts by mass of 3-triethoxysilyl-N-(1,3 dimethyl-butylidene)propylamine (Shin-Etsu Chemical Co., Ltd., trade name: KBE-9103), as an inorganic filler, 100.0 parts by mass of spherical silica (manufactured by Admatechs Co., Ltd., trade name: Admanano, average particle size: about 0.300 μm) and 550 parts by mass of cyclohexanone were mixed with stirring. After mixing these, vacuum deaeration was performed to obtain a varnish of the adhesive composition.

Then, the above varnish is applied on a release-treated polyethylene terephthalate film having a thickness of 38 μm, which is a base film, and dried by heating at 90° C. for 5 minutes and 130° C. for 5 minutes to obtain an adhesive layer in a B stage state. An adhesive sheet having a thickness of 20 μm formed on a substrate film was produced.

(Comparative Example 1)
Example 1 except that the imine silane coupling agent was changed to 3-ureidopropyltriethoxysilane (manufactured by Momentive Performance Materials Japan LLC, trade name: A-1160) which is a ureido silane coupling agent. An adhesive sheet was produced in the same manner as in.

<Adhesive strength measurement>
The adhesive strength of the adhesive sheet to the substrate was measured using a universal bond tester (trade name: series-4000, manufactured by Daiji Japan Co., Ltd.).

A dicing sheet (dicing tape) was attached to the adhesive layer surface of the adhesive sheet, the base film was peeled off, and then a semiconductor wafer having a thickness of 400 μm was laminated on the other adhesive layer surface on a hot plate. Then, the semiconductor wafer was divided into individual pieces through a dicing process to obtain semiconductor chips with an adhesive layer of 5 mm×5 mm.

The semiconductor chip with the adhesive layer is pressure-bonded to a glass epoxy substrate coated with a solder resist (Taiyo Nissan Corporation, product name: AUS308) under the conditions of 120° C., 0.1 MPa, and 5 seconds, and the adhesive is applied. The stress was examined when the bond failure between the layer and the substrate or chip occurred. At this time, no curing process was performed between the pressure bonding and the measurement. Table 2 shows the measurement results of the adhesive strength at the measurement temperature of 175°C. The term "destruction of adhesion" as used herein includes both cohesive failure in which the adhesive layer itself is destroyed and interfacial failure in which failure occurs at the interface between the adhesive layer and the substrate or chip. That is, in the present specification, “adhesive strength” includes “bulk strength”. The measurement temperature of 175° C. is a general temperature in the sealing process. At this time, in order to prevent the encapsulant from invading between the chips or between the chips and the substrate, it is said that an adhesive strength of 0.5 MPa or more between the chips and the substrate and 0.3 MPa or more between the chips and the substrate are required. ing.

<Measurement of storage elastic modulus>
The storage elastic modulus of the adhesive layer of the adhesive sheet was measured using a dynamic viscoelasticity measuring device (Rheology Co., Ltd., trade name: DVE Rheospectra).

After peeling the substrate film from the adhesive sheet, a plurality of adhesive layers were laminated at 70° C. to form a film having a film thickness of 100 to 300 μm, and cut into a strip shape having a length of 50 mm and a width of 4 mm. The produced strip-shaped film was measured for storage elastic modulus from room temperature to 270° C. at a chuck distance of 10 mm and a temperature rising rate of 10° C./min. The storage elastic modulus at 150° C. is shown in Table 2 as a result.

The set temperature of 150° C. is a general temperature in the wire bonding process. By measuring the storage elastic modulus of the film at this temperature, it becomes a criterion for determining whether die cracks occur during wire bonding. It is believed that if the adhesive layer has a storage elastic modulus of 5 MPa or more at a measurement temperature of 150° C., chip cracking can be prevented even if the thickness is 3 μm.

<Evaluation of embedding of irregularities on the substrate>
A dicing sheet was attached to the adhesive layer of the adhesive sheet, the substrate film was peeled off, and a semiconductor wafer having a thickness of 75 μm was laminated on the hot plate in the other surface of the adhesive layer. Then, the semiconductor wafer was divided into individual pieces through a dicing process to obtain 7.5 mm×7.5 mm semiconductor chips with an adhesive layer.

A sample in which the semiconductor chip with the adhesive layer is attached to a substrate having irregularities with a width of 30 μm and a depth of 50 μm under the conditions of 120° C., 0.1 MPa, and 1 second is prepared, and the sample is placed on a hot plate at 150° C. for 2 hours. Heat treated. After that, using a molding encapsulating material (Hitachi Chemical Co., Ltd., trade name: CEL-9700HF), encapsulation was performed under the conditions of 175° C., 6.9 MPa, and 120 seconds to produce an evaluation package. The cross section of the package was observed with an ultrasonic microscope to evaluate the filling property of the adhesive layer on the irregularities (width 30 μm, depth 50 μm) on the substrate. If there were no voids in the uneven portion, it was designated as "A", and if there were voids it was designated as "B". The results are shown in Table 2.

When the adhesive layer of the present invention is used, the curing step can be omitted and sufficient adhesive strength can be obtained only by pressure bonding, and high storage elasticity can be obtained while maintaining the embedding property of the irregularities on the wiring board. It was confirmed that rationalization could be achieved. That is, the adhesive layer according to the present invention can improve the throughput by shortening or omitting the curing step, and while maintaining the heat resistance history, it is sufficient that stress is not concentrated on the semiconductor chip when thinned. It has a high storage elastic modulus. According to the adhesive layer of the present invention, it is possible to improve the reliability of the semiconductor device and to improve the processing speed and the yield of the semiconductor device.

DESCRIPTION OF SYMBOLS 1... Adhesive layer, 3... Base film, 12a, 12b... Semiconductor element, 13... Support member, 14... Wire, 15... Sealing material, 100... Adhesive sheet, 210... Semiconductor device.

Claims (7)

Epoxy resin, an epoxy resin curing agent, an epoxy group-containing (meth) acrylic copolymer, and an adhesive composition containing an imine-based silane coupling agent, the adhesive layer formed into a sheet ,
In the adhesive composition, relative to the weight of the epoxy group-containing (meth) acrylic copolymer, the ratio of the total weight of said epoxy resin and said epoxy resin curing agent, Ru der 0.05-0.50, Adhesive sheet. The adhesive sheet according to claim 1, wherein the imine-based silane coupling agent contains an imine-based silane coupling agent represented by the following general formula (3).

[In the formula, R ¹ represents a divalent hydrocarbon group, R ² and R ³ each independently represent a hydrogen atom or a monovalent hydrocarbon group, and R ⁴ represents an alkyl group. ] The adhesive sheet according to claim 1 or 2, wherein the content of the imine-based silane coupling agent in the adhesive composition is 0.5 to 5 mass% based on the total solid content of the adhesive composition. .. 4. The epoxy group-containing (meth)acrylic copolymer is a copolymer having a glass transition temperature of −50 to 30° C. and a weight average molecular weight of 100,000 or more. Adhesive sheet. The adhesive composition further contains an inorganic filler having an average particle size of 0.005 to 0.5 μm in an amount of 1 to 50 with respect to 100 parts by mass of the total solid content of the adhesive composition excluding the inorganic filler. The adhesive sheet according to any one of claims 1 to 5 , which comprises a mass part. Wherein the thickness of the adhesive layer is 3 to 30 .mu.m, the adhesive sheet according to any one of claims 1-5. The semiconductor element and the supporting member, the die bonding step of thermocompression bonding through the adhesive layer in the adhesive sheet according to any one of claims 1 to 6
A wire bonding step of electrically connecting the semiconductor element and the supporting member with a wire while heating,
A sealing step of sealing the semiconductor element with a resin,
And a method for manufacturing a semiconductor device having.

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