TWI889669B - Adhesive composition, film-shaped adhesive, adhesive sheet, and method for manufacturing semiconductor device - Google Patents

Abstract

The present invention discloses an adhesive composition comprising a thermosetting resin, a hardener, an elastomer, and an inorganic filler. The hardener comprises a phenolic resin having an alicyclic ring, and the elastomer content is 10 to 80 parts by mass per 100 parts by mass of the thermosetting resin. Also disclosed is a film-like adhesive using the adhesive composition. Furthermore, disclosed are methods for manufacturing an adhesive sheet and a semiconductor device using the film-like adhesive.

Description

Adhesive composition, film-shaped adhesive, adhesive sheet, and method for manufacturing semiconductor device

The present invention relates to an adhesive composition, a film-shaped adhesive, an adhesive sheet, and a method for manufacturing a semiconductor device.

Silver paste has traditionally been used to bond semiconductor chips to supporting members. However, with the recent miniaturization and integration of semiconductor chips, demands for smaller and denser supporting members have also emerged. However, the use of silver paste can sometimes lead to problems during wire bonding due to paste exposure or the tilt of the semiconductor chip, resulting in difficulties controlling film thickness and the formation of voids.

Therefore, in recent years, film adhesives have been used to bond semiconductor chips to supporting members (see, for example, Patent Document 1). When using a bonding sheet comprising a dicing tape and a film adhesive laminated on the dicing tape, the film adhesive is applied to the backside of a semiconductor wafer and then singulated by dicing, resulting in semiconductor chips coated with the film adhesive. The resulting semiconductor chips coated with the film adhesive are then attached to a supporting member via the film adhesive and bonded by thermal compression.

[Prior Art Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Publication No. 2007-053240

However, as semiconductor chips become smaller, the force applied per unit area during thermal compression bonding increases, sometimes causing a phenomenon called bleed where the film adhesive protrudes from the semiconductor chip.

Furthermore, when film adhesives are used as film-over-wire (FOW) for embedding wires or film-over-die (FOD) for embedding semiconductor chips, high fluidity is required during thermal compression bonding to improve embedding properties. Consequently, the frequency and amount of oozing tend to increase. In some cases, oozing may even reach the top surface of the semiconductor chip, potentially causing electrical failure or wire bonding defects.

This invention was developed in light of this practical situation. Its main purpose is to provide an adhesive composition that has good embedding properties during hot pressing and can suppress seepage.

One aspect of the present invention provides an adhesive composition. The adhesive composition comprises a thermosetting resin, a hardener, an elastomer, and an inorganic filler. The hardener comprises a phenolic resin having an alicyclic ring. The elastomer content is 10 to 80 parts by mass per 100 parts by mass of the thermosetting resin. This adhesive composition exhibits excellent embedding properties during hot pressing and suppresses bleeding.

The thermosetting resin may be an epoxy resin. The epoxy resin may include a bisphenol F type epoxy resin.

The elastomer may be an acrylic resin.

The inorganic filler may be silicon dioxide. The content of the inorganic filler may be 25% by mass or more based on the total amount of the adhesive composition.

Based on the total amount of the adhesive composition, the combined content of the thermosetting resin, hardener, elastomer, and inorganic filler may be 95% by mass or more.

The adhesive composition may further contain a hardening accelerator.

The adhesive composition can be used in a semiconductor device in which a first semiconductor element is connected to a substrate via a first wire by wire bonding, and a second semiconductor element is press-bonded onto the first semiconductor element. The adhesive composition can be used to press-bond the second semiconductor element and embed at least a portion of the first wire.

Furthermore, the present invention may relate to the use of a composition comprising a thermosetting resin, a hardener, and an elastomer, wherein the hardener comprises a phenolic resin having an alicyclic ring, as an adhesive or for manufacturing an adhesive. In a semiconductor device in which a first semiconductor element is wire-bonded to a substrate via a first wire, and a second semiconductor element is press-bonded onto the first semiconductor element, the composition is used to press-bond the second semiconductor element and embed at least a portion of the first wire.

Another aspect of the present invention provides a film-shaped adhesive, which is formed by forming the adhesive composition into a film.

Another aspect of the present invention provides an adhesive sheet comprising a substrate and the film-like adhesive disposed on the substrate.

The substrate may be a dicing tape. Furthermore, in this specification, a bonding sheet whose substrate is a dicing tape is sometimes referred to as a "dicing and die-bonding integrated bonding sheet."

The adhesive sheet may further include a protective film laminated on the surface of the film-like adhesive opposite to the substrate.

Another aspect of the present invention provides a method for manufacturing a semiconductor device, comprising: a wire bonding step of electrically connecting a first semiconductor element on a substrate via a first wire; a lamination step of applying the film adhesive to one side of a second semiconductor element; and a die bonding step of press-bonding the second semiconductor element to which the film adhesive is applied via the film adhesive, thereby embedding at least a portion of the first wire in the film adhesive.

Furthermore, the semiconductor device may be a wire-embedded semiconductor device in which a first semiconductor chip is connected to a semiconductor substrate via a first wire by wire bonding, and a second semiconductor chip is press-bonded onto the first semiconductor chip via an adhesive film, thereby burying at least a portion of the first wire in the adhesive film. Alternatively, the semiconductor device may be a chip-embedded semiconductor device in which the first wire and the first semiconductor chip are buried in the adhesive film.

The present invention provides an adhesive composition that exhibits excellent embedding properties during thermal compression bonding and suppresses oozing. Consequently, a film-shaped adhesive formed from this adhesive composition can be effectively used as a film-over-die (FOD) film adhesive for embedding semiconductor chips or as a film-over-wire (FOW) film adhesive for embedding wires. Furthermore, the present invention provides a method for manufacturing an adhesive sheet and a semiconductor device using this film-shaped adhesive.

10: Film adhesive

14:Substrate

20: Base material

30: Protective film

41: Follow-up agent

42: Sealing material

84, 94: Circuit diagram

88: First Conductor

90:Organic substrate

98: Second wire

100, 110: Next film

200: Semiconductor devices

Wa: First semiconductor element

Waa: Second semiconductor device

Figure 1 is a schematic cross-sectional view of a film-shaped adhesive according to one embodiment.

Figure 2 is a schematic cross-sectional view of a bonding sheet according to one embodiment.

Figure 3 is a schematic cross-sectional view of another embodiment of a bonding sheet.

FIG4 is a schematic cross-sectional view showing a semiconductor device according to one embodiment.

FIG5 is a schematic cross-sectional view showing a series of steps in a method for manufacturing a semiconductor device according to one embodiment.

FIG6 is a schematic cross-sectional view showing a series of steps in a method for manufacturing a semiconductor device according to one embodiment.

FIG7 is a schematic cross-sectional view showing a series of steps in a method for manufacturing a semiconductor device according to one embodiment.

FIG8 is a schematic cross-sectional view showing a series of steps in a method for manufacturing a semiconductor device according to one embodiment.

FIG9 is a schematic cross-sectional view showing a series of steps in a method for manufacturing a semiconductor device according to one embodiment.

The following describes embodiments of the present invention with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

In this specification, (meth)acrylic acid refers to acrylic acid or its corresponding methacrylic acid. The same applies to other similar expressions such as (meth)acryloyl.

[Adhesive composition]

The adhesive composition of this embodiment comprises: (A) a thermosetting resin, (B) a hardener, (C) an elastomer, and (D) an inorganic filler. The adhesive composition is thermosetting, undergoes a semi-cured (B-stage) state, and can reach a fully cured (C-stage) state after a curing process.

<(A) Ingredient: Thermosetting resin>

From the viewpoint of adhesion, component (A) may be an epoxy resin. Epoxy resins can be used without particular limitation as long as they are compounds having an epoxy group in the molecule. Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, bisphenol F novolac type epoxy resins, diphenol Styrene-based epoxy resins, epoxy resins containing a triazine skeleton, epoxy resins containing a fluorene skeleton, trisphenolmethane-based epoxy resins, biphenyl-based epoxy resins, xylylene-based epoxy resins, biphenylaralkyl-based epoxy resins, naphthalene-based epoxy resins, and epoxy resins having an alicyclic ring structure can be used. These epoxy resins can be used alone or in combination. Among these, the epoxy resin can also include bisphenol F-based epoxy resin. The inclusion of bisphenol F-based epoxy resin tends to improve embeddability. Furthermore, from the perspective of fluidity, the epoxy resin may also include an epoxy resin having an alicyclic ring, and the epoxy resin having an alicyclic ring may be a dicyclopentadiene-type epoxy resin (an epoxy resin having a dicyclopentadiene structure).

The epoxy equivalent weight of component (A) is not particularly limited and may be 90 g/eq to 600 g/eq, 100 g/eq to 500 g/eq, or 120 g/eq to 450 g/eq. Component (A) having an epoxy equivalent weight within this range tends to achieve good reactivity and fluidity. When component (A) includes a bisphenol F-type epoxy resin, the epoxy equivalent weight of the bisphenol F-type epoxy resin may be less than 180 g/eq, and may be 170 g/eq or less, or 160 g/eq or less, from the perspective of embedding properties. The epoxy equivalent weight of the bisphenol F-type epoxy resin may be 90 g/eq or greater, 100 g/eq or greater, or 120 g/eq or greater.

<(B) Component: Hardener>

Component (B) contains a phenolic resin (B-1) having an alicyclic ring.

Component (B-1) is a compound containing an alicyclic ring and a hydroxyl group within the molecule. The hydroxyl group may be bonded to the alicyclic ring or a portion outside the alicyclic ring of the compound via a single bond or a linking group (e.g., an alkylene group, an oxyalkylene group, etc.). The inclusion of component (B-1) as a hardener provides excellent embedding properties during hot pressing and suppresses bleeding.

The component (B-1) may be, for example, a phenolic resin represented by the following general formula (1).

In formula (1), E represents an alicyclic ring, G represents a single bond or an alkylene group, and R1 each independently represents a hydrogen atom or a monovalent hydrocarbon group. ⁿ¹ represents an integer from 1 to 10, and m represents an integer from 1 to 3.

E may have 4-12, 5-11, or 6-10 carbon atoms. E may be monocyclic or polycyclic, preferably polycyclic, and more preferably a dicyclopentadiene ring. The alkylene group in G may be an alkylene group having 1-5 carbon atoms, such as methylene, ethylene, propylene, butylene, or pentylene. G is preferably a single bond. The monovalent alkyl group in ^R1 may be, for example, an alkyl group such as methyl, ethyl, propyl, butyl, or pentyl; an aryl group such as phenyl or naphthyl; or a heteroaryl group such as pyridyl. ^R1 is preferably a hydrogen atom.

The phenolic resin represented by the general formula (1) may be a phenolic resin represented by the following general formula (1a).

In formula (1a), n1 has the same meaning as described above.

Examples of commercially available phenolic resins represented by general formula (1a) include J-DPP-85, J-DPP-95, and J-DPP-115 (all manufactured by JFE Chemical Co., Ltd.).

The hydroxyl equivalent weight of component (B-1) is not particularly limited and can be 80 g/eq to 400 g/eq, 90 g/eq to 350 g/eq, or 100 g/eq to 300 g/eq. A hydroxyl equivalent weight of component (B-1) within this range tends to provide good reactivity and fluidity.

The content of component (B-1) can be 5% by mass or more, 10% by mass or more, or 15% by mass or more, based on the total weight of the adhesive composition. A content of 5% by mass or more, based on the total weight of the adhesive composition, provides better embedding properties during hot pressing and effectively suppresses the tendency for bleeding. The content of component (B-1) can be 50% by mass or less, 40% by mass or less, or 30% by mass or less, based on the total weight of the adhesive composition.

In addition to the component (B-1), the component (B) may further contain a phenolic resin (B-2) having no alicyclic ring. Examples of component (B-2) include novolac-type phenolic resins obtained by condensing or co-condensing phenols such as phenol, cresol, resorcin, o-catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol, and/or naphthols such as α-naphthol, β-naphthol, and dihydroxynaphthalene with a compound having an aldehyde group such as formaldehyde under an acidic catalyst; and phenol aralkyl resins, naphthol aralkyl resins, biphenyl aralkyl-type phenolic resins, and phenyl aralkyl-type phenolic resins synthesized from phenols such as allylated bisphenol A, allylated bisphenol F, allylated naphthenediol, phenol novolac, phenol, and/or naphthols with dimethoxy-p-xylene or bis(methoxymethyl)biphenyl. These can be used alone or in combination of two or more.

The hydroxyl equivalent weight of component (B-2) is not particularly limited and can be 80 g/eq to 400 g/eq, 90 g/eq to 350 g/eq, or 100 g/eq to 300 g/eq. When the hydroxyl equivalent weight of component (B-2) is within this range, good reactivity and fluidity tend to be achieved.

The content of component (B-1) can be 50% to 100% by mass based on the total amount of component (B). The content of component (B-1) can be 60% or more, or 70% or more, based on the total amount of component (B). The content of component (B-2) can be 0% to 50% by mass based on the total amount of component (B). The content of component (B-2) can be 40% or less, or 30% or less, based on the total amount of component (B).

From the perspective of curability, when component (A) is an epoxy resin, the ratio of the epoxy equivalent of the epoxy resin to the hydroxy equivalent of component (B) (epoxy equivalent of the epoxy resin/hydroxy equivalent of the phenolic resin) can be 0.30/0.70 to 0.70/0.30, 0.35/0.65 to 0.65/0.35, 0.40/0.60 to 0.60/0.40, or 0.45/0.55 to 0.55/0.45. An equivalent ratio of 0.30/0.70 or greater tends to achieve more adequate curability. An equivalent ratio of 0.70/0.30 or less prevents excessive viscosity increases, resulting in more adequate fluidity.

The combined content of components (A) and (B) can be 30% to 70% by mass based on the total weight of the adhesive composition. The combined content of components (A) and (B) can be 33% by mass or greater, 36% by mass or greater, or 40% by mass or greater, and can be 65% by mass or less, 60% by mass or less, or 55% by mass or less. When the combined content of components (A) and (B) is 30% by mass or greater, based on the total weight of the adhesive composition, adhesion tends to be improved. When the combined content of components (A) and (B) is 70% by mass or less, the viscosity can be prevented from becoming excessively low, and bleeding tends to be further suppressed.

<(C) Component: Elastomer>

The adhesive composition of this embodiment contains (C) an elastomer. Component (C) preferably comprises a polymer having a glass transition temperature (Tg) of 50°C or less.

Examples of component (C) include acrylic resins, polyester resins, polyamide resins, polyimide resins, silicone resins, butadiene resins, acrylonitrile resins, and modified forms thereof.

From the perspective of solubility and fluidity in solvents, component (C) may include an acrylic resin. Here, the term "acrylic resin" refers to a polymer containing structural units derived from (meth)acrylate esters. The acrylic resin preferably contains structural units derived from (meth)acrylate esters having crosslinking functional groups such as epoxy groups, alcoholic or phenolic hydroxyl groups, or carboxyl groups. Alternatively, the acrylic resin may be an acrylic rubber, such as a copolymer of (meth)acrylate and acrylonitrile.

The glass transition temperature (Tg) of acrylic resin can be -50°C to 50°C or -30°C to 30°C. If the Tg of acrylic resin is above -50°C, the flexibility of the adhesive composition tends to be prevented from becoming too high. This makes it easier to cut the film adhesive during wafer dicing, preventing the formation of burrs. If the Tg of acrylic resin is below 50°C, the flexibility of the adhesive composition tends to be suppressed. This makes it easier to fully fill the gaps when the film adhesive is attached to the wafer. In addition, chipping during dicing, which is caused by a decrease in the adhesion of the wafer, can be prevented. Here, the glass transition temperature (Tg) refers to the value measured using a thermomechanical analysis (TMA) tester (TA Instruments, TMA400Q).

The weight-average molecular weight (Mw) of acrylic resins can be between 100,000 and 3,000,000, or between 500,000 and 2,000,000. Acrylic resins with Mw within this range can appropriately control film-forming properties, film strength, flexibility, and viscosity, while also providing excellent reflow properties and enhancing embeddability. Here, Mw refers to the value measured by gel permeation chromatography (GPC) and converted using a calibration curve based on standard polystyrene.

Commercially available acrylic resins include, for example, SG-70L, SG-708-6, WS-023 EK30, SG-280 EK23, and SG-P3 solvent-modified product (all manufactured by Nagase ChemteX Co., Ltd.).

The content of component (C) is 10 to 80 parts by mass per 100 parts by mass of component (A). The content of component (C) can be 20 parts by mass or greater, 30 parts by mass or greater, 35 parts by mass or greater, 40 parts by mass or greater, or 42 parts by mass or greater, and can be 75 parts by mass or less, 72 parts by mass or less, 70 parts by mass or less, or 68 parts by mass or less. When the content of component (C) is 10 parts by mass or greater per 100 parts by mass of component (A), the workability (e.g., bendability) of the film-forming adhesive tends to be improved. When the content of component (C) is 80 parts by mass or less per 100 parts by mass of component (A), the flexibility of the adhesive composition tends to be prevented from becoming excessively high. This facilitates cutting of the film adhesive during wafer dicing, preventing the formation of burrs. Furthermore, if the content of component (C) is 80 parts by mass or less per 100 parts by mass of component (A), embedding properties of conductive wires or semiconductor chips tend to improve.

The content of component (C) can be 10 parts by mass or more, 20 parts by mass or more, or 30 parts by mass or more per 100 parts by mass of the total amount of components (A) and (B), and can be 80 parts by mass or less, 75 parts by mass or less, 60 parts by mass or less, or 55 parts by mass or less. A content of 10 parts by mass or more of component (C) per 100 parts by mass of the total amount of components (A) and (B) tends to improve the workability (e.g., bendability) of the film-forming adhesive. A content of 80 parts by mass or less of component (C) per 100 parts by mass of the total amount of components (A) and (B) tends to further prevent the adhesive composition from becoming excessively soft. This makes it easier to cut the film adhesive during wafer dicing, and is more likely to prevent the formation of burrs.

<(D) Ingredient: Inorganic Filler>

Examples of inorganic fillers 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, crystalline silica, and amorphous silica. These can be used alone or in combination. To further enhance the thermal conductivity of the resulting film-like adhesive, the inorganic filler may include aluminum oxide, aluminum nitride, boron nitride, crystalline silica, or amorphous silica. In addition, from the perspective of adjusting the melt viscosity of the adhesive composition and imparting tactile properties to the adhesive composition, the inorganic filler may be aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, crystalline silica, or amorphous silica, or may be silica (crystalline silica or amorphous silica).

To further improve adhesion, the average particle size of component (D) can be 0.005μm to 0.5μm or 0.05μm to 0.3μm. The average particle size here refers to the value calculated based on the Brunauer-Emmett-Teller (BET) specific surface area.

From the perspective of surface compatibility with solvents and other components, as well as bonding strength, component (D) can be surface treated with a surface treatment agent. Examples of surface treatment agents include silane coupling agents. Examples of functional groups in silane coupling agents include vinyl, (meth)acryl, epoxy, hydroxyl, amino, diamine, alkoxy, and ethoxy groups.

Based on the total amount of the adhesive composition, the content of component (D) may be 25% by mass or more, or 28% by mass or more, or 30% by mass or more. If the content of component (D) is 25% by mass or more, based on the total amount of the adhesive composition, the cutting properties of the adhesive layer before curing tend to be improved, and the bonding strength of the adhesive layer after curing tends to be improved. In this way, sufficient cutting properties can be ensured even in thicker film adhesives (e.g., 20 μm or more, preferably 30 μm or more) for FOD/FOW applications. There is no particular upper limit to the content of component (D), and it may be 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total amount of the adhesive composition. If the content of component (D) is 60% by mass or less based on the total amount of the adhesive composition, a decrease in fluidity can be suppressed, preventing the elastic modulus of the cured film adhesive from becoming excessively high.

In the adhesive composition of this embodiment, component (A), component (B), component (C), and component (D) are the main components. Based on the total weight of the adhesive composition, the total content of component (A), component (B), component (C), and component (D) can be 95% by mass or more, or 97% by mass or more, and can be 100% by mass or less, or 99% by mass or less.

<(E) Component: Hardening Accelerator>

The adhesive composition of this embodiment may contain (E) a hardening accelerator. The hardening accelerator is not particularly limited, and commonly used ones can be used. Examples of component (E) include imidazoles and their derivatives, organophosphorus compounds, diamines, tertiary amines, and quaternary ammonium salts. These may be used alone or in combination of two or more. Among these, imidazoles and their derivatives are preferred for better reactivity.

Examples of imidazoles include 2-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-cyanoethyl-2-methylimidazole. These can be used alone or in combination of two or more.

The content of component (E) can be 0.01 to 3 parts by mass or 0.03 to 1 part by mass per 100 parts by mass of the total of components (A), (B), and (C). A content of component (E) within this range tends to achieve both hardening properties and reliability.

<Other ingredients>

The adhesive composition of this embodiment may further contain antioxidants, silane coupling agents, rheology control agents, and other ingredients as other components. These ingredients may be present in an amount of 0.01 to 3 parts by mass relative to 100 parts by mass of the total amount of components (A), (B), and (C).

The adhesive composition of this embodiment can be used as an adhesive varnish diluted with a solvent. The solvent is not particularly limited as long as it can dissolve the components other than component (D). Examples of solvents include aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene, and p-isopropyltoluene; aliphatic hydrocarbons such as hexane and heptane; cyclic alkanes such as methylcyclohexane; cyclic ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and 4-hydroxy-4-methyl-2-pentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, and γ-butyrolactone; carbonates such as ethyl carbonate and propyl carbonate; and amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. These solvents may be used alone or in combination. Among these, from the viewpoint of solubility and boiling point, the solvent may be toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone.

Based on the total mass of the adhesive varnish, the solid content concentration in the adhesive varnish can be 10% to 80% by mass.

The adhesive varnish can be prepared by mixing and kneading components (A), (B), (C), (D), and a solvent, and optionally, component (E) and other components. Mixing and kneading can be performed using a suitable combination of conventional dispersing machines, such as a stirrer, pestle, three-roll mill, ball mill, or bead mill. When mixing component (D), mixing time can be shortened by pre-mixing component (D) with low-molecular-weight components before blending the high-molecular-weight components. Furthermore, after preparing the adhesive varnish, air bubbles can be removed from the varnish by vacuum degassing or other methods.

[Film Adhesive]

Figure 1 is a schematic cross-sectional view of a film-like adhesive according to one embodiment. Film-like adhesive 10 is formed by forming the adhesive composition described above into a film. Film-like adhesive 10 may be in a semi-cured (B-stage) state. This film-like adhesive 10 can be formed by applying the adhesive composition to a support film. When using an adhesive varnish, the adhesive varnish can be applied to the support film and then heated and dried to remove the solvent, thereby forming film-like adhesive 10.

The supporting membrane is not particularly limited. Examples include membranes made of polytetrafluoroethylene, polyethylene, polypropylene, polymethylpentene, polyethylene terephthalate, and polyimide. The thickness of the supporting membrane can be, for example, 10 μm to 200 μm or 20 μm to 170 μm.

The adhesive varnish can be applied to the support film using any known method, including blade coating, roll coating, spray coating, gravure coating, rod coating, and curtain coating. Heat drying conditions are not particularly limited as long as they allow the solvent to fully volatilize. For example, drying can be performed at 50°C to 200°C for 0.1 to 90 minutes.

The thickness of the film adhesive can be adjusted appropriately depending on the application. To ensure sufficient embedding of uneven surfaces such as semiconductor chips, wires, and substrate wiring circuits, the thickness of the film adhesive can be 20μm to 200μm, 30μm to 200μm, or 40μm to 150μm.

[Continuation]

Figure 2 is a schematic cross-sectional view of an adhesive sheet according to one embodiment. The adhesive sheet 100 includes a substrate 20 and the aforementioned film-shaped adhesive 10 disposed on the substrate.

The substrate 20 is not particularly limited and may be a substrate film. The substrate film may be the same as the supporting film.

The substrate 20 may be a dicing tape. This type of adhesive sheet can be used as a dicing and die-bonding integrated adhesive sheet. In this case, since the lamination step for the semiconductor wafer is performed in one step, the operation can be efficient.

Examples of dicing tape include plastic films such as polytetrafluoroethylene film, polyethylene terephthalate film, polyethylene film, polypropylene film, polymethylpentene film, and polyimide film. Furthermore, the dicing tape may be subjected to surface treatments such as primer coating, UV treatment, corona discharge treatment, polishing, and etching, as needed. Dicing tape is preferably adhesive. Such dicing tape may be adhesive to the plastic film or may have an adhesive layer applied to one side of the plastic film.

Adhesive sheet 100 can be formed by applying an adhesive composition to a substrate film, similar to the method for forming the film-like adhesive described above. The method for applying the adhesive composition to substrate 20 can be the same as the method for applying the adhesive composition to a support film described above.

The adhesive sheet 100 can be formed using a pre-made film-like adhesive. In this case, the adhesive sheet 100 can be formed by laminating using a roll press, vacuum laminating press, or the like under specified conditions (e.g., room temperature (20°C) or heated). While the adhesive sheet 100 can be manufactured continuously, for efficiency, it is preferably formed using a roll press under heated conditions.

From the perspective of embedding semiconductor chips, wires, and substrate wiring, the thickness of the film adhesive 10 can be 20μm to 200μm, 30μm to 200μm, or 40μm to 150μm. A thickness of 20μm or greater tends to provide more sufficient bonding strength, while a thickness of 200μm or less is economical and can meet the demand for miniaturization of semiconductor devices.

Figure 3 is a schematic cross-sectional view of another embodiment of an adhesive sheet. Adhesive sheet 110 further includes a protective film 30 laminated on the surface of film-like adhesive 10 opposite substrate 20. Protective film 30 can be the same as the supporting film described above. The thickness of the protective film can be, for example, 15 μm to 200 μm or 70 μm to 170 μm.

[Semiconductor device]

FIG4 is a schematic cross-sectional view of a semiconductor device according to one embodiment. Semiconductor device 200 is formed by connecting a first semiconductor element Wa in the first stage to a substrate 14 via a first wire 88 by wire bonding. A second semiconductor element Waa is then press-bonded onto the first semiconductor element Wa via a film adhesive 10, thereby embedding at least a portion of the first wire 88 in the film adhesive 10. The semiconductor device may be a wire-embedded semiconductor device in which at least a portion of the first wire 88 is embedded, or a semiconductor device in which both the first wire 88 and the first semiconductor element Wa are embedded. Furthermore, in the semiconductor device 200, the substrate 14 is electrically connected to the second semiconductor element Waa via the second wire 98, and the second semiconductor element Waa is sealed by the sealing material 42.

The thickness of the first semiconductor element Wa can be between 10μm and 170μm, and the thickness of the second semiconductor element Waa can be between 20μm and 400μm. The first semiconductor element Wa embedded in the film adhesive 10 is a controller chip used to drive the semiconductor device 200.

Substrate 14 includes an organic substrate 90 with circuit patterns 84 and 94 formed two locations on its surface. A first semiconductor element Wa is press-bonded to circuit pattern 94 via adhesive 41. A second semiconductor element Waa is press-bonded to substrate 14 via adhesive film 10, covering the portion of circuit pattern 94 not bonded to it, the first semiconductor element Wa, and a portion of circuit pattern 84. Adhesive film 10 fills the unevenness created by circuit patterns 84 and 94 on substrate 14. Furthermore, a resin sealant 42 seals the second semiconductor element Waa, circuit pattern 84, and second wire 98.

[Method for manufacturing semiconductor device]

The semiconductor device manufacturing method of this embodiment includes: a first wire bonding step of electrically connecting a first semiconductor element on a substrate via a first conductive wire; a lamination step of applying the aforementioned film adhesive to one side of a second semiconductor element; and a die attach step of laminating the second semiconductor element, to which the film adhesive is applied, via the film adhesive, thereby embedding at least a portion of the first conductive wire in the film adhesive.

Figures 5 to 9 are schematic cross-sectional views illustrating a series of steps in a method for manufacturing a semiconductor device according to one embodiment. The semiconductor device 200 of this embodiment is a semiconductor device in which a first conductive wire 88 and a first semiconductor element Wa are embedded. It can be manufactured using the following process. First, as shown in Figure 5 , the first semiconductor element Wa, having a bonding agent 41, is press-bonded onto the circuit pattern 94 on the substrate 14. The circuit pattern 84 on the substrate 14 and the first semiconductor element Wa are electrically bonded via the first conductive wire 88 (a first wire bonding step).

Next, a laminating sheet 100 is laminated on one side of a semiconductor wafer (e.g., 100μm thick, 8-inch size), and the substrate 20 is removed. A film adhesive 10 (e.g., 110μm thick) is then attached to the single side of the semiconductor wafer. A dicing tape is then attached to the film adhesive 10, and the film is cut into a predetermined size (e.g., 7.5mm square). As shown in FIG6 , a second semiconductor device Waa with the film adhesive 10 attached is obtained (laminating step).

The temperature conditions for the lamination step can be 50°C to 100°C or 60°C to 80°C. If the lamination step temperature is 50°C or higher, good adhesion to the semiconductor wafer can be achieved. If the lamination step temperature is 100°C or lower, excessive flow of the film adhesive 10 during the lamination step can be suppressed, thereby preventing variations in thickness.

Examples of dicing methods include: dicing with a rotating blade, and cutting with a laser to separate the adhesive film or both the wafer and the adhesive film.

The second semiconductor element Waa, with the film adhesive 10 attached, is then press-bonded to the substrate 14, to which the first semiconductor element Wa is bonded via the first wire 88. Specifically, as shown in FIG7 , the second semiconductor element Waa, with the film adhesive 10 attached, is positioned so that the film adhesive 10 covers the first wire 88 and the first semiconductor element Wa. Subsequently, as shown in FIG8 , the second semiconductor element Waa is press-bonded to the substrate 14 to secure it (die bonding step). The die bonding step preferably involves pressing the film adhesive 10 at 80°C to 180°C and 0.01 MPa to 0.50 MPa for 0.5 to 3.0 seconds. After the die bonding step, the film adhesive 10 is pressurized and heated at 60°C to 175°C and 0.3MPa to 0.7MPa for more than 5 minutes.

Next, as shown in FIG9 , after the substrate 14 and the second semiconductor element Waa are electrically connected via the second wires 98 (a second wire bonding step), the circuit pattern 84, the second wires 98, and the second semiconductor element Waa are sealed with a sealing material 42. By completing these steps, a semiconductor device 200 is manufactured.

As another embodiment, the semiconductor device may be a wire-embedded semiconductor device in which at least a portion of the first wire 88 is embedded.

[Example]

The following examples are given to illustrate the present invention in more detail. However, the present invention is not limited to these examples.

(Examples 1 to 8 and Comparative Examples 1 to 4)

<Production of the follow-up film>

The following components were mixed in the proportions (parts by mass) shown in Tables 1 and 2, and cyclohexanone was used as a solvent to prepare a varnish containing a 40% solids adhesive composition. The resulting varnish was then filtered through a 100-mesh filter and vacuum defoamed. The defoamed varnish was then applied to a 38μm thick, release-treated polyethylene terephthalate (PET) film as a substrate. The applied varnish was then heat-dried in two stages: at 90°C for 5 minutes, then at 140°C for 5 minutes. In this way, a 110 μm thick adhesive film with a semi-cured (B-stage) adhesive film was obtained on the substrate film.

The components in Tables 1 and 2 are as follows.

(A) Thermosetting resin

A-1: Epoxy resin with a dicyclopentadiene structure, manufactured by DIC Corporation, trade name: HP-7200L, epoxy equivalent weight: 250g/eq~280g/eq

A-2: Epoxy resin with a dicyclopentadiene structure, manufactured by Nippon Kayaku Co., Ltd., trade name: XD-1000, epoxy equivalent weight: 254 g/eq

A-3: Resin epoxy resin, manufactured by Daicell Co., Ltd., trade name: EHPE3150, epoxy equivalent weight: 170g/eq~190g/eq

A-4: Multifunctional aromatic epoxy resin, manufactured by Printec Co., Ltd., trade name: VG3101L, epoxy equivalent weight: 210 g/eq

A-5: Cresol novolac-type epoxy resin, manufactured by Nippon Steel & Sumitomo Chemicals Co., Ltd., trade name: YDCN-700-10, epoxy equivalent weight: 209 g/eq

A-6: Bisphenol F epoxy resin (liquid at 25°C), manufactured by DIC Corporation, trade name: EXA-830CRP, epoxy equivalent: 159 g/eq

(B) Hardener

(B-1) Phenolic resin with an alicyclic ring

B-1-1: Phenolic resin with a dicyclopentadiene structure represented by general formula (1a), manufactured by JFE Chemical Co., Ltd., trade name: J-DPP-85, hydroxyl equivalent: 164g/eq~167g/eq, softening point: 85°C~89°C

B-1-2: Phenolic resin with a dicyclopentadiene structure represented by general formula (1a), manufactured by JFE Chemical Co., Ltd., trade name: J-DPP-115, hydroxyl equivalent: 177g/eq~181g/eq, softening point 107℃~116℃

(B-2) Phenolic resins without alicyclic rings

B-2-1: Bisphenol A novolac-type phenolic resin, manufactured by DIC Corporation, trade name: LF-4871, hydroxyl equivalent: 118 g/eq

B-2-2: Phenyl aralkyl phenol resin, manufactured by Mitsui Chemicals, Co., Ltd., trade name: XLC-LL, hydroxyl equivalent weight: 175g/eq

B-2-3: Phenyl aralkyl phenol resin, manufactured by Air Water Co., Ltd., trade name: HE100C-30, hydroxyl equivalent weight: 170g/eq

(C) Elastomer

C-1: Epoxy-containing acrylic resin (acrylic rubber), manufactured by Nagase Chemicals Co., Ltd., trade name: SG-P3 solvent-modified product, weight-average molecular weight: 800,000, glycidyl functional group monomer ratio: 3%, Tg: -7°C

C-2: Acrylic resin (acrylic rubber), manufactured by Nagase Chemical Co., Ltd., trade name: SG-70L, weight-average molecular weight: 900,000, acid value: 5 mgKOH/g, Tg: -13°C

C-3: Carboxyl-containing acrylic resin (acrylic rubber), manufactured by Nagase Chemicals Co., Ltd., trade name: SG-708-6, weight-average molecular weight: 700,000, acid value: 9 mgKOH/g, Tg: 4°C

(D) Inorganic fillers

D-1: Silica filler dispersion, fused silica, manufactured by Admatechs Co., Ltd., trade name: SC2050-HLG, average particle size: 0.50 μm

(E) Hardening accelerator

E-1: 1-Cyanoethyl-2-phenylimidazole, manufactured by Shikoku Chemical Industries, Ltd., trade name: Curezol 2PZ-CN

<Evaluation of various physical properties>

The obtained adhesive sheets were evaluated for embedding properties and seepage.

[Embedded Evaluation]

The following evaluation samples were prepared to evaluate the embedding properties of the die-bonding adhesive. The base film of the film-like adhesive (110 μm thick) obtained above was peeled off and attached to a dicing tape to create a dicing-and-bonding die-bonding die-bonding die. Next, a 100 μm-thick semiconductor wafer (8 inches) was prepared, heated to 70°C, and attached to the adhesive side of the dicing-and-bonding die-bonding die. This semiconductor wafer was then diced into 7.5 mm squares to obtain semiconductor chips A. Next, a 50μm-thick semiconductor wafer (8-inch) and a different dicing and die-bonding integrated adhesive sheet (Hitachi Chemical Co., Ltd., trade name: HR9004-10) (10μm thick) were prepared. The semiconductor wafer was heated to 70°C and attached to the adhesive side of the dicing and die-bonding integrated adhesive sheet. The semiconductor wafer was then cut into 4.5mm squares, yielding semiconductor wafers B with die-bonding films. Next, a 260μm-thick evaluation substrate coated with solder resist (Taiyo Nippon Sanso Co., Ltd., trade name: AUS308) was prepared. Press bonding was performed at 120°C, 0.20 MPa, and 2 seconds, with the die-bonding film of semiconductor wafer B in contact with the solder resist of the evaluation substrate. Subsequently, the film adhesive of semiconductor chip A was brought into contact with the semiconductor wafer of semiconductor chip B under conditions of 120°C, 0.20 MPa, and 1.5 seconds to obtain evaluation samples. At this time, alignment was performed so that the previously pressed semiconductor chip B was centered on semiconductor chip A. The evaluation samples obtained in this manner were observed for the presence of voids using an ultrasonic digital imaging diagnostic device (manufactured by Insight Co., Ltd., probe: 75 MHz). If voids were observed, the ratio of void area per unit area was calculated, and these analysis results were used to evaluate embeddability. The evaluation criteria are as follows. The results are shown in Tables 1 and 2.

A: No gaps were observed.

B: Although voids were observed, their proportion was less than 5% by area.

C: Voids are observed, and the proportion is 5% or more by area.

[Percolation Evaluation]

For samples rated "A" or "B" in the embeddability evaluation, the amount of permeation was evaluated. Samples for the permeation evaluation were prepared in the same manner as the samples used for the embeddability evaluation. Using a microscope, the amount of film adhesive permeation was measured from the center of each of the four sides of the sample, and the maximum value was defined as the permeation amount. The results are shown in Tables 1 and 2.

As shown in Tables 1 and 2, Examples 1 to 6, which contain phenolic resins containing alicyclic rings, maintain good embedding properties and suppress bleed-out, compared to Comparative Examples 1 to 4, which do not contain phenolic resins containing alicyclic rings. These results confirm that the adhesive composition of the present invention has good embedding properties and suppresses bleed-out during hot press bonding.

[Industrial Availability]

As demonstrated by the above results, the adhesive composition of the present invention exhibits excellent embedding properties and reduced bleeding during hot pressing. Therefore, a film-shaped adhesive formed from the adhesive composition can be effectively used as a film-over-die (FOD) film adhesive for embedding a die or as a film-over-wire (FOW) film adhesive for embedding a wire.

Claims (9)

An adhesive composition comprising a thermosetting resin, a hardener, an elastomer, and an inorganic filler, wherein the thermosetting resin is an epoxy resin, the epoxy resin comprising a bisphenol F-type epoxy resin, the hardener comprising a phenolic resin having an alicyclic ring, and the elastomer content is 10 to 80 parts by mass relative to 100 parts by mass of the thermosetting resin, based on the total weight of the adhesive composition, and the inorganic filler content is 25% by mass or more, based on the total weight of the adhesive composition. The combined content of the thermosetting resin, the hardener, the elastomer, and the inorganic filler is 95% by mass or greater. In a semiconductor device in which a first semiconductor element is wire-bonded to a substrate via a first wire, and a second semiconductor element is press-bonded onto the first semiconductor element, the adhesive composition is used to press-bond the second semiconductor element and embed at least a portion of the first wire, or to embed both the first wire and the first semiconductor element. The adhesive composition according to claim 1, wherein the elastomer is an acrylic resin. The adhesive composition as described in claim 1 or claim 2, wherein the inorganic filler is silicon dioxide. The adhesive composition according to claim 1 or claim 2 further comprises a hardening accelerator. A film-like adhesive, wherein the adhesive composition according to any one of claims 1 to 4 is formed into a film. A bonding sheet comprising: a substrate; and the film-shaped bonding agent according to claim 5 disposed on the substrate. The splice sheet as described in claim 6, wherein the substrate is a dicing tape. The adhesive sheet according to claim 6 or claim 7 further comprises a protective film laminated on the surface of the film-like adhesive opposite to the substrate. A method for manufacturing a semiconductor device comprises: a wire bonding step of electrically connecting a first semiconductor element on a substrate via a first wire; a lamination step of applying the film adhesive described in claim 5 to one side of a second semiconductor element; and a die bonding step of press-bonding the second semiconductor element to which the film adhesive is applied via the film adhesive, thereby embedding at least a portion of the first wire in the film adhesive.