JP7655362B2 - Semiconductor Device - Google Patents

Description

The present invention relates to a film-like adhesive, an adhesive sheet, a semiconductor device, and a method for manufacturing the same.

In recent years, stacked MCPs (Multi Chip Packages), in which semiconductor elements (semiconductor chips) are stacked in multiple stages, have become widespread and are used as memory semiconductor packages for mobile phones and mobile audio devices. As mobile phones and other devices become more multifunctional, semiconductor packages are being made faster, more dense, and more highly integrated. Accordingly, copper is being used as the wiring material for semiconductor chip circuits to increase speed. Also, from the perspective of improving the reliability of connections to complex mounting boards and promoting heat dissipation from semiconductor packages, lead frames made of copper are beginning to be used.

However, copper is prone to corrosion, and in order to reduce costs, there is a trend toward simplifying the coating materials used to ensure the insulation of the circuit surface, making it difficult to ensure the electrical properties of the semiconductor package. In particular, in semiconductor packages in which semiconductor chips are stacked in multiple stages, copper ions generated by corrosion tend to move inside the adhesive, easily causing loss of electrical signals within the semiconductor chip or between semiconductor chips.

In addition, from the perspective of increasing functionality, semiconductor elements are often connected to complex mounting boards, and there is a tendency to prefer lead frames made of copper to improve connection reliability. Even in such cases, loss of electrical signals due to copper ions generated from the lead frame can become a problem.

Furthermore, in semiconductor packages that use copper-based components, there is a high possibility that copper ions will be generated from the components, causing electrical malfunctions, and sufficient HAST resistance may not be achieved.

From the viewpoint of preventing loss of electrical signals, adhesives that capture copper ions generated within semiconductor packages are being investigated. For example, Patent Document 1 discloses an adhesive sheet for manufacturing semiconductor devices that contains a thermoplastic resin that has an epoxy group and no carboxyl group, and an organic complex-forming compound that has a heterocyclic compound containing a tertiary nitrogen atom as a ring atom and forms a complex with a cation.

However, conventional adhesives are not sufficient in terms of suppressing copper ion permeation through the adhesive and in terms of adhesive strength, and there is still room for improvement.

JP 2013-026566 A

Therefore, the main objective of the present invention is to provide a film-like adhesive that sufficiently suppresses copper ion permeation within the adhesive while also having excellent adhesive strength.

After extensive research, the inventors discovered that by adjusting the inorganic filler content in the film adhesive to a specific range, it is possible to sufficiently suppress copper ion permeation into the adhesive while also achieving superior adhesive strength, leading to the completion of the present invention.

One aspect of the present invention provides a film-like adhesive for bonding a semiconductor element to a support member on which the semiconductor element is mounted, the film-like adhesive containing a thermosetting resin, a curing agent, an acrylic rubber, and an inorganic filler, the content of the inorganic filler being 0.5 to 10 parts by mass per 100 parts by mass of the total mass of the thermosetting resin, the curing agent, the acrylic rubber, and the inorganic filler, and the thickness of the film-like adhesive being 15 μm or less.

The content of inorganic filler is 0.5 to 10 parts by mass per 100 parts by mass of the total mass of the thermosetting resin, curing agent, acrylic rubber, and inorganic filler. When the content of inorganic filler is 0.5 parts by mass or more, the adhesive strength, wafer adhesion, elastic modulus, and bulk strength of the film-like adhesive tend to be excellent. When the content of inorganic filler is 10 parts by mass or less, copper ion permeation in the adhesive is sufficiently suppressed, and the appearance of the coated surface and embeddability also tend to be excellent.

In another aspect, the present invention provides an adhesive sheet comprising a substrate and the above-mentioned film-like adhesive provided on one surface of the substrate. The substrate may be a dicing tape.

In another aspect, the present invention provides a semiconductor device comprising a semiconductor element, a support member on which the semiconductor element is mounted, and an adhesive member provided between the semiconductor element and the support member and for adhering the semiconductor element and the support member, the adhesive member being a cured product of the above-mentioned film-like adhesive. The support member may include a member made of copper.

In another aspect, the present invention provides a method for manufacturing a semiconductor device, comprising a step of bonding a semiconductor element and a support member using the above-mentioned film-like adhesive.

In another aspect, the present invention provides a method for manufacturing a semiconductor device, comprising the steps of: attaching the film-like adhesive of the adhesive sheet to a semiconductor wafer; cutting the semiconductor wafer to which the film-like adhesive has been attached, thereby producing a plurality of individual semiconductor elements with the film-like adhesive; and adhering the semiconductor elements with the film-like adhesive to a support member. The method for manufacturing a semiconductor device may further comprise the step of heating using a reflow furnace.

According to the present invention, a film-like adhesive is provided that has excellent adhesive strength while sufficiently suppressing copper ion permeation through the adhesive. The present invention also provides an adhesive sheet and a semiconductor device that use such a film-like adhesive. Furthermore, the present invention also provides a method for manufacturing a semiconductor device that uses the film-like adhesive or the adhesive sheet.

FIG. 1 is a schematic cross-sectional view showing one embodiment of a film-like adhesive. FIG. 1 is a schematic cross-sectional view showing one embodiment of an adhesive sheet. FIG. 4 is a schematic cross-sectional view showing another embodiment of the adhesive sheet. FIG. 4 is a schematic cross-sectional view showing another embodiment of the adhesive sheet. FIG. 4 is a schematic cross-sectional view showing another embodiment of the adhesive sheet. 1 is a schematic cross-sectional view showing an embodiment of a semiconductor device; FIG. 11 is a schematic cross-sectional view showing another embodiment of a semiconductor device.

Below, an embodiment of the present invention will be described with reference to the drawings as appropriate. However, the present invention is not limited to the following embodiment. In the following embodiment, the components (including steps, etc.) are not essential unless specifically stated. The size of the components in each figure is conceptual, and the relative relationship of the size between the components is not limited to that shown in each figure.

The same applies to the numerical values and their ranges in this specification, and they do not limit the present invention. In this specification, the numerical ranges indicated using "~" indicate ranges that include the numerical values before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in this specification, the upper or lower limit value of the numerical range may be replaced with the value shown in the examples.

In this specification, (meth)acrylate means acrylate or the corresponding methacrylate. The same applies to other similar expressions such as (meth)acryloyl group and (meth)acrylic copolymer.

The film-like adhesive according to one embodiment is a film-like adhesive for bonding a semiconductor element to a support member on which the semiconductor element is mounted, the film-like adhesive containing (A) a thermosetting resin, (B) a curing agent, (C) an acrylic rubber, and (D) an inorganic filler, the content of the inorganic filler being 0.5 to 10 parts by mass per 100 parts by mass of the total mass of the thermosetting resin, the curing agent, the acrylic rubber, and the inorganic filler, and the thickness of the film-like adhesive being 15 μm or less.

The film-like adhesive can be obtained by forming an adhesive composition containing (A) a thermosetting resin, (B) a curing agent, (C) an acrylic rubber, and (D) an inorganic filler into a film. The film-like adhesive and adhesive composition may be capable of passing through a semi-cured (B stage) state and then becoming fully cured (C stage) after a curing process.

Component (A): Thermosetting Resin From the viewpoint of adhesiveness, component (A) may be an epoxy resin. Any epoxy resin having an epoxy group in the molecule may be used without particular limitation. 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, stilbene type epoxy resins, triazine skeleton-containing epoxy resins, fluorene skeleton-containing epoxy resins, triphenol methane type epoxy resins, biphenyl type epoxy resins, xylylene type epoxy resins, biphenyl aralkyl type epoxy resins, naphthalene type epoxy resins, polyfunctional phenols, and diglycidyl ether compounds of polycyclic aromatics such as anthracene. These may be used alone or in combination of two or more. Among these, the component (A) may be a cresol novolac type epoxy resin, a bisphenol F type epoxy resin, or a bisphenol A type epoxy resin from the viewpoint of the tackiness and flexibility of the film.

The epoxy equivalent of the epoxy resin is not particularly limited, but may be 90 to 300 g/eq, 110 to 290 g/eq, or 110 to 290 g/eq. When the epoxy equivalent of the epoxy resin is in such a range, the film adhesive tends to maintain its bulk strength while ensuring its fluidity.

Component (B): Curing Agent Component (B) may be a phenolic resin that can be a curing agent for epoxy resins. Any phenolic resin can be used without particular limitation as long as it has a phenolic hydroxyl group in the molecule. Examples of phenolic resins include novolak-type phenolic resins obtained by condensing or co-condensing phenols such as phenol, cresol, resorcin, catechol, bisphenol A, bisphenol F, phenylphenol, aminophenol, etc. and/or naphthols such as α-naphthol, β-naphthol, dihydroxynaphthalene, etc. with a compound having an aldehyde group such as formaldehyde under an acidic catalyst, allylated bisphenol A, allylated bisphenol F, allylated naphthalenediol, phenol novolak, phenol aralkyl resins synthesized from phenols such as phenol and/or naphthols with dimethoxyparaxylene or bis(methoxymethyl)biphenyl, naphthol aralkyl resins, etc. These may be used alone or in combination of two or more. Among these, the phenol resin may be a phenol aralkyl resin or a naphthol aralkyl resin.

The hydroxyl equivalent of the phenolic resin may be 70 g/eq or more, or 70 to 300 g/eq. If the hydroxyl equivalent of the phenolic resin is 70 g/eq or more, the storage modulus of the film tends to be improved, and if it is 300 g/eq or less, it is possible to prevent defects due to the generation of foaming, outgassing, etc.

From the viewpoint of curability, the ratio of the epoxy equivalent of the epoxy resin to the hydroxyl equivalent of the phenolic resin (epoxy equivalent of the epoxy resin/hydroxyl equivalent of the phenolic resin) may 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. If the equivalent ratio is 0.30/0.70 or more, more sufficient curability tends to be obtained. If the equivalent ratio is 0.70/0.30 or less, it is possible to prevent the viscosity from becoming too high, and more sufficient fluidity can be obtained.

The total content of components (A) and (B) may be 5 to 50 parts by mass, 10 to 40 parts by mass, or 15 to 30 parts by mass, based on 100 parts by mass of the total mass of components (A), (B), (C), and (D). When the total content of components (A) and (B) is 5 parts by mass or more, the elastic modulus tends to improve due to crosslinking. When the total content of components (A) and (B) is 50 parts by mass or less, film handleability tends to be maintained.

(C) component: acrylic rubber The (C) component is a rubber having a structural unit derived from a (meth)acrylic acid ester as a main component. The content of the structural unit derived from a (meth)acrylic acid ester in the (C) component may be, for example, 70% by mass or more, 80% by mass or more, or 90% by mass or more based on the total amount of structural units. The (C) component may contain a structural unit derived from a (meth)acrylic acid ester having a crosslinkable functional group such as an epoxy group, an alcoholic or phenolic hydroxyl group, or a carboxyl group. The (C) component may contain a structural unit derived from acrylonitrile within a range that satisfies the condition of formula (1) described below, but the (C) component may not contain a structural unit derived from acrylonitrile because it is possible to further suppress copper ion permeation in the adhesive and has better embeddability.

In the infrared absorption spectrum of the component (C), when the height of the absorption peak due to the stretching vibration of the carbonyl group is P _CO and the height of the peak due to the stretching vibration of the nitrile group is P _CN , P _CO and P _CN may satisfy the condition of the following formula (1).
P _CN /P _CO <0.070 (1)

Here, the carbonyl group is mainly derived from the (meth)acrylic acid ester structural unit, and the nitrile group is mainly derived from the acrylonitrile structural unit. Note that the height of the absorption peak derived from the stretching vibration of the carbonyl group (P _CO ) and the height of the peak derived from the stretching vibration of the nitrile group (P _CN ) are as defined in the Examples.

A small P _CN /P _CO ratio means that the component (C) contains fewer structural units derived from acrylonitrile. Therefore, a component (C) that does not contain any structural units derived from acrylonitrile can theoretically satisfy the condition of formula (1).

P _CN /P _CO is less than 0.070, and may be 0.065 or less, 0.060 or less, 0.055 or less, 0.050 or less, 0.040 or less, 0.030 or less, 0.020 or less, or 0.010 or less. When P _CN /P _CO is less than 0.070, it may be possible to sufficiently suppress copper ion permeation in the adhesive. In addition, as the value of P _CN /P _CO becomes smaller, copper ion permeation in the adhesive can be more sufficiently suppressed. In addition, as the value of P _CN /P _CO becomes smaller, the cohesive force of the (C) component decreases, so that the embeddability also tends to be more excellent.

The glass transition temperature (Tg) of the (C) component may be -50 to 50°C or -30 to 30°C. When the Tg of the (C) component is -50°C or higher, the flexibility of the adhesive tends to be prevented from becoming too high. This makes it easier to cut the film-like adhesive during wafer dicing, and makes it possible to prevent the occurrence of burrs. When the Tg of the (C) component is 50°C or lower, the flexibility of the adhesive tends to be suppressed from decreasing. This makes it easier to sufficiently fill voids when the film-like adhesive is attached to the wafer. In addition, it makes it possible to prevent chipping during dicing due to a decrease in wafer adhesion. Here, the glass transition temperature (Tg) refers to a value measured using a DSC (differential scanning calorimeter) (for example, Thermo Plus 2, manufactured by Rigaku Corporation).

The weight average molecular weight (Mw) of component (C) may be 100,000 to 3,000,000 or 200,000 to 2,000,000. When the Mw of component (C) is in this range, the film formability, strength in the film state, flexibility, tackiness, etc. can be appropriately controlled, and the reflowability and embeddability can be improved. Here, Mw means a value measured by gel permeation chromatography (GPC) and converted using a calibration curve based on standard polystyrene.

Commercially available products of component (C) include, for example, SG-70L, SG-P3, SG-708-6, WS-023 EK30, and SG-280 EK23 (all manufactured by Nagase ChemteX Corporation). Commercially available products of component (C) that do not contain structural units derived from acrylonitrile include, for example, KH-CT-865 (manufactured by Hitachi Chemical Co., Ltd.).

The content of component (C) may be 50 to 95 parts by mass, 55 to 90 parts by mass, or 60 to 85 parts by mass per 100 parts by mass of the total mass of components (A), (B), (C), and (D). When the content of component (C) is within such a range, copper ion permeation through the adhesive tends to be more sufficiently suppressed.

(D) component: inorganic filler Examples of the (D) component include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whisker, boron nitride, silica, etc. These may be used alone or in combination of two or more. Among these, the (D) component may be silica from the viewpoint of adjusting the melt viscosity.

From the viewpoint of fluidity, the average particle size of component (D) may be 0.01 to 1 μm, 0.01 to 0.8 μm, or 0.03 to 0.5 μm. Here, the average particle size means a value calculated by converting from the BET specific surface area. As the average particle size of component (D) becomes smaller, the appearance of the coating surface tends to be improved and thin film coatability tends to be improved.

The shape of component (D) is not particularly limited, but may be spherical.

The content of the (D) component is 0.5 to 10 parts by mass relative to 100 parts by mass of the total mass of the (A), (B), (C), and (D) components. When the content of the (D) component is 0.5 parts by mass or more, the adhesive strength of the film-like adhesive, wafer adhesion, elastic modulus, and bulk strength tend to be excellent. When the content of the (D) component is 10 parts by mass or less, copper ion permeation in the adhesive is sufficiently suppressed, and the appearance and embeddability of the coated surface tend to be excellent. The content of the (D) component may be 1 part by mass or more, 3 parts by mass or more, or 5 parts by mass or more, or 10 parts by mass or less, 9 parts by mass or less, 8.5 parts by mass or less, or 8 parts by mass or less.

The film-like adhesive (adhesive composition) may further contain (E) a coupling agent, (F) a curing accelerator, etc.

Component (E): Coupling Agent Component (E) may be a silane coupling agent. Examples of the silane coupling agent include γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, etc. These may be used alone or in combination of two or more.

(F) component: curing accelerator The (F) component is not particularly limited, and can be a commonly used one. (F) component includes, for example, imidazoles and their derivatives, organic phosphorus compounds, secondary amines, tertiary amines, quaternary ammonium salts, etc. These may be used alone or in combination of two or more. Among these, the (F) component may be imidazoles and their derivatives from the viewpoint of reactivity.

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

The film-like adhesive (adhesive composition) may further contain other components. Examples of other components include pigments, ion scavengers, antioxidants, etc.

The content of the (E) component, the (F) component, and other components may be 0 to 30 parts by mass per 100 parts by mass of the total mass of the (A) component, the (B) component, the (C) component, and the (D) component.

Figure 1 is a schematic cross-sectional view showing one embodiment of a film-like adhesive. The film-like adhesive 1 (adhesive film) shown in Figure 1 is formed by molding an adhesive composition into a film. The film-like adhesive 1 may be in a semi-cured (B stage) state. Such a film-like adhesive 1 can be formed by applying the adhesive composition to a support film. When using a varnish of the adhesive composition (adhesive varnish), the (A) component, the (B) component, the (C) component, the (D) component, and other components added as necessary are mixed in a solvent, the mixed liquid is mixed or kneaded to prepare an adhesive varnish, the adhesive varnish is applied to a support film, and the solvent is removed by heating and drying, thereby forming the film-like adhesive 1.

The support film is not particularly limited as long as it can withstand the above-mentioned heat drying, and may be, for example, a polyester film, a polypropylene film, a polyethylene terephthalate film, a polyimide film, a polyetherimide film, a polyether naphthalate film, a polymethylpentene film, or the like. The support film may be a multi-layer film combining two or more types of films, and may have a surface treated with a silicone-based, silica-based, or other release agent. The thickness of the support film may be, for example, 10 to 200 μm or 20 to 170 μm.

Mixing or kneading can be carried out using a conventional mixer, a mixing machine, a three-roll mill, a ball mill, or other dispersing machine, in any suitable combination.

The solvent used in preparing the adhesive varnish is not limited as long as it can uniformly dissolve, knead or disperse each component, and any conventionally known solvent can be used. Examples of such solvents include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, toluene, and xylene. In terms of drying speed and cost, the solvent may be methyl ethyl ketone, cyclohexanone, etc.

The adhesive varnish can be applied to the support film by any known method, such as knife coating, roll coating, spray coating, gravure coating, bar coating, curtain coating, etc. There are no particular restrictions on the conditions for heat drying, so long as the solvent used is sufficiently evaporated, but heating can be performed at 50 to 150°C for 1 to 30 minutes.

If the thickness of the film-like adhesive is 15 μm or less, the distance between the semiconductor element and the support member on which the semiconductor element is mounted becomes short, and therefore defects due to copper ions tend to occur more easily. The film-like adhesive according to this embodiment is capable of sufficiently suppressing copper ion permeation within the adhesive, and therefore the thickness can be set to 15 μm or less. The thickness of the film-like adhesive 1 may be 12 μm or less or 10 μm or less. There is no particular lower limit to the thickness of the film-like adhesive 1, but it can be, for example, 1 μm or more.

In one embodiment, the copper ion permeation time of the film-like adhesive 1 in the semi-cured (B stage) state may be more than 260 minutes, and may be 270 minutes or more, 280 minutes or more, 290 minutes or more, or 300 minutes or more. In another embodiment, the copper ion permeation time of the film-like adhesive 1 in the semi-cured (B stage) state may be more than 70 minutes, 75 minutes or more, or 80 minutes or more. By setting the copper ion permeation time in this range, it is expected that defects caused by copper ions will be less likely to occur even if defects such as insufficient curing occur during the production of a semiconductor device.

In one embodiment, the adhesive strength (die shear strength) of the film-like adhesive 1 (i.e., the cured product of the film-like adhesive) in the C-stage state may be greater than 0.5 MPa, or may be 0.8 MPa or more, or 1.0 MPa or more. In other embodiments, the adhesive strength (die shear strength) of the film-like adhesive in the C-stage state may be greater than 1.5 MPa, or may be 1.6 MPa or more, 1.7 MPa or more, or 1.8 MPa or more. If the adhesive strength is in this range, defects due to peeling are unlikely to occur during the production of the semiconductor manufacturing device, and it is predicted that the higher the adhesive strength, the lower the probability of defects due to peeling occurring.

Figure 2 is a schematic cross-sectional view showing one embodiment of an adhesive sheet. The adhesive sheet 100 shown in Figure 2 comprises a substrate 2 and a film-like adhesive 1 provided on the substrate 2. Figure 3 is a schematic cross-sectional view showing another embodiment of an adhesive sheet. The adhesive sheet 110 shown in Figure 3 comprises a substrate 2, a film-like adhesive 1 provided on the substrate 2, and a cover film 3 provided on the surface of the film-like adhesive 1 opposite the substrate 2.

The substrate 2 is not particularly limited, but may be a substrate film. The substrate film may be the same as the support film described above.

The cover film 3 is used to prevent damage or contamination of the film-like adhesive, and may be, for example, a polyethylene film, a polypropylene film, a film treated with a surface release agent, etc. The thickness of the cover film 3 may be, for example, 15 to 200 μm or 70 to 170 μm.

The adhesive sheets 100, 110 can be formed by applying an adhesive composition to a substrate film in the same manner as the method for forming the film-like adhesive described above. The method for applying the adhesive composition to the substrate 2 may be the same as the method for applying the adhesive composition to the support film described above.

The adhesive sheet 110 can be obtained by further laminating a cover film 3 onto the film-like adhesive 1.

The adhesive sheets 100, 110 may be formed using a film-like adhesive prepared in advance. In this case, the adhesive sheet 100 can be formed by laminating under predetermined conditions (e.g., room temperature (20°C) or in a heated state) using a roll laminator, vacuum laminator, or the like. The adhesive sheet 100 may be formed in a heated state using a roll laminator, since this can be produced continuously and is highly efficient.

Another embodiment of the adhesive sheet is a dicing/die bonding integrated adhesive sheet in which the substrate 2 is a dicing tape. When a dicing/die bonding integrated adhesive sheet is used, the lamination process to the semiconductor wafer is performed only once, which can improve work efficiency.

Examples of dicing tapes include plastic films such as polytetrafluoroethylene film, polyethylene terephthalate film, polyethylene film, polypropylene film, polymethylpentene film, and polyimide film. The dicing tape may be subjected to a surface treatment such as primer coating, UV treatment, corona discharge treatment, polishing treatment, and etching treatment, as necessary. The dicing tape may be adhesive. Such a dicing tape may be the above-mentioned plastic film to which adhesiveness has been imparted, or may be the above-mentioned plastic film to which an adhesive layer has been provided on one side. The adhesive layer may be either a pressure-sensitive type or a radiation-curing type, and is not particularly limited as long as it has sufficient adhesive strength to prevent the semiconductor elements from scattering during dicing, and has low adhesive strength to the extent that the semiconductor elements are not damaged in the subsequent semiconductor element pick-up process, and conventionally known adhesives can be used.

The thickness of the dicing tape may be 60 to 150 μm or 70 to 130 μm from the standpoint of economy and ease of handling of the film.

Examples of such integrated dicing and die bonding adhesive sheets include those having the configuration shown in FIG. 4 and those having the configuration shown in FIG. 5. FIG. 4 is a schematic cross-sectional view showing another embodiment of the adhesive sheet. FIG. 5 is a schematic cross-sectional view showing another embodiment of the adhesive sheet. The adhesive sheet 120 shown in FIG. 4 comprises a dicing tape 7, a pressure-sensitive adhesive layer 6, and a film-like adhesive 1, in this order. The adhesive sheet 130 shown in FIG. 5 comprises a dicing tape 7 and a film-like adhesive 1 provided on the dicing tape 7.

The adhesive sheet 120 can be obtained, for example, by providing a pressure-sensitive adhesive layer 6 on a dicing tape 7, and then laminating a film-like adhesive 1 on the pressure-sensitive adhesive layer 6. The adhesive sheet 130 can be obtained, for example, by bonding the dicing tape 7 and the film-like adhesive 1 together.

The film-like adhesive and adhesive sheet may be used in the manufacture of a semiconductor device, which may include a process of laminating a film-like adhesive and dicing tape to a semiconductor wafer or an already diced semiconductor element (semiconductor chip) at 0°C to 90°C, cutting with a rotary blade, laser, or stretching to obtain a semiconductor element with the film-like adhesive, and then adhering the semiconductor element with the film-like adhesive to an organic substrate, a lead frame, or another semiconductor element.

Semiconductor wafers include, for example, single crystal silicon, polycrystalline silicon, various ceramics, and compound semiconductors such as gallium arsenide.

The film-like adhesive and adhesive sheet can be used as a die-bonding adhesive for bonding semiconductor elements such as ICs and LSIs to lead frames such as 42 alloy lead frames and copper lead frames; plastic films such as polyimide resin and epoxy resin; substrates such as glass nonwoven fabrics impregnated and cured with plastics such as polyimide resin and epoxy resin; and support members for mounting semiconductors such as ceramics such as alumina.

The film adhesive and adhesive sheet are also suitable for use as an adhesive for bonding semiconductor elements together in a stacked-PKG, which is a structure in which multiple semiconductor elements are stacked. In this case, one of the semiconductor elements serves as a support member on which the semiconductor element is mounted.

Film-like adhesives and adhesive sheets can also be used, for example, as protective sheets to protect the back surface of a semiconductor element in a flip-chip type semiconductor device, or as sealing sheets to seal the gap between the front surface of a semiconductor element in a flip-chip type semiconductor device and an adherend.

A semiconductor device manufactured using the film-like adhesive will be specifically described with reference to the drawings. Note that in recent years, semiconductor devices with various structures have been proposed, and the use of the film-like adhesive according to this embodiment is not limited to semiconductor devices with the structures described below.

Figure 6 is a schematic cross-sectional view showing one embodiment of a semiconductor device. The semiconductor device 200 shown in Figure 6 includes a semiconductor element 9, a support member 10 on which the semiconductor element 9 is mounted, and an adhesive member (cured film-like adhesive 1c) provided between the semiconductor element 9 and the support member 10 and bonding the semiconductor element 9 and the support member 10. The connection terminals (not shown) of the semiconductor element 9 are electrically connected to external connection terminals (not shown) via wires 11 and are sealed with a sealant 12.

Figure 7 is a schematic cross-sectional view showing another embodiment of a semiconductor device. In the semiconductor device 210 shown in Figure 7, the first-stage semiconductor element 9a is adhered to a support member 10 on which terminals 13 are formed by an adhesive member (cured film-like adhesive 1c), and the second-stage semiconductor element 9b is adhered to the first-stage semiconductor element 9a by an adhesive member (cured film-like adhesive 1c). The connection terminals (not shown) of the first-stage semiconductor element 9a and the second-stage semiconductor element 9b are electrically connected to external connection terminals via wires 11 and sealed by a sealing material 12. In this way, the film-like adhesive of this embodiment can be suitably used in semiconductor devices having a structure in which multiple semiconductor elements are stacked.

The semiconductor device (semiconductor package) shown in Figures 6 and 7 is obtained, for example, by interposing a film-like adhesive between a semiconductor element and a support member or between two semiconductor elements, and then bonding the two together by heating and pressing them, and then, as necessary, going through a wire bonding process, a sealing process using a sealing material, a heating and melting process including solder reflow, etc. The heating temperature in the heating and pressing process is usually 20 to 250°C, the load is usually 0.1 to 200 N, and the heating time is usually 0.1 to 300 seconds.

As a method for interposing a film-like adhesive between a semiconductor element and a support member or between semiconductor elements, as described above, a semiconductor element with a film-like adhesive may be prepared in advance and then attached to the support member or the semiconductor element.

The support member may include a member made of copper. In the semiconductor device according to this embodiment, the semiconductor element and the support member are bonded by the cured film adhesive 1c. Therefore, even if a member made of copper is used as a component of the semiconductor device, the influence of the copper ions generated from the member can be reduced, and the occurrence of electrical defects caused by the copper ions can be sufficiently suppressed.

Here, examples of components made of copper include lead frames, wiring, wires, heat dissipation materials, etc., and no matter which component copper is used in, it is possible to reduce the effects of copper ions.

Next, an embodiment of a method for manufacturing a semiconductor device using the integrated dicing and die bonding adhesive sheet shown in FIG. 4 will be described. Note that the method for manufacturing a semiconductor device using the integrated dicing and die bonding adhesive sheet is not limited to the method for manufacturing a semiconductor device described below.

First, the semiconductor wafer is pressed onto the film-like adhesive 1 in the adhesive sheet 120 (dicing/die bonding integrated adhesive sheet), and is fixed by being adhered (mounting process). This process may be performed while pressing with a pressing means such as a pressing roll.

Next, the semiconductor wafer is diced. This cuts the semiconductor wafer to a predetermined size to produce a plurality of individual semiconductor elements (semiconductor chips) with a film-like adhesive. Dicing can be performed, for example, from the circuit side of the semiconductor wafer in a conventional manner. In this process, for example, a cutting method called a full cut, in which cutting is performed all the way to the dicing tape, a method in which a half cut is made in the semiconductor wafer and then divided by cooling and pulling, a cutting method using a laser, etc. can be used. There are no particular limitations on the dicing device used in this process, and any conventionally known device can be used.

The semiconductor elements are picked up in order to peel off the semiconductor elements bonded and fixed to the dicing/die bonding integrated adhesive sheet. There are no particular limitations on the pick-up method, and various conventionally known methods can be used. For example, there is a method in which individual semiconductor elements are pushed up from the dicing/die bonding integrated adhesive sheet side by a needle, and the pushed-up semiconductor elements are picked up by a pick-up device.

Here, if the adhesive layer is of a radiation (e.g., ultraviolet) curing type, the pickup is performed after irradiating the adhesive layer with radiation. This reduces the adhesive strength of the adhesive layer to the film-like adhesive, making it easier to peel off the semiconductor element. As a result, the semiconductor element can be picked up without being damaged.

Next, the semiconductor element with the film-like adhesive formed by dicing is adhered to a support member for mounting the semiconductor element via the film-like adhesive. The adhesion may be performed by pressure bonding. There are no particular limitations on the die bonding conditions, and they can be set appropriately as necessary. Specifically, for example, the die bonding temperature can be 80 to 160°C, the bonding load can be 5 to 15 N, and the bonding time can be 1 to 10 seconds.

If necessary, a step of thermally curing the film-like adhesive may be provided. By thermally curing the film-like adhesive that bonds the support member and the semiconductor element in the above-mentioned bonding step, it is possible to bond and fix the adhesive more firmly. When performing thermal curing, pressure may be applied at the same time to harden the adhesive. The heating temperature in this step can be appropriately changed depending on the components of the film-like adhesive. The heating temperature may be, for example, 60 to 200°C. The temperature or pressure may be changed in stages.

Next, a wire bonding process is performed in which the tip of the terminal portion (inner lead) of the support member is electrically connected to the electrode pad on the semiconductor element with a bonding wire. For example, gold wire, aluminum wire, copper wire, etc. are used as the bonding wire. The temperature during wire bonding may be within the range of 80 to 250°C or 80 to 220°C. The heating time may be several seconds to several minutes. Wiring may be performed by combining ultrasonic vibration energy and compression energy by applied pressure while heated within the above temperature range.

Next, an encapsulation process is performed to encapsulate the semiconductor element with encapsulating resin. This process is performed to protect the semiconductor element or bonding wires mounted on the support member. This process is performed by molding the encapsulating resin in a mold. The encapsulating resin may be, for example, an epoxy-based resin. The heat and pressure during encapsulation bury the substrate and residue, preventing peeling due to air bubbles at the adhesive interface.

Next, in the post-curing process, any sealing resin that was not sufficiently cured in the sealing process is completely cured. Even if the film-like adhesive is not thermally cured in the sealing process, in this process, the film-like adhesive is thermally cured as the sealing resin hardens, making it possible to bond and fix the parts. The heating temperature in this process can be set appropriately depending on the type of sealing resin, and may be within the range of 165 to 185°C, for example, and the heating time may be approximately 0.5 to 8 hours.

Next, the semiconductor element with the film-like adhesive attached to the support member is heated using a reflow furnace. In this process, a resin-encapsulated semiconductor device may be surface-mounted on the support member. Examples of surface mounting methods include reflow soldering, in which solder is first supplied onto a printed wiring board, then heated and melted by hot air or the like, and soldered. Examples of heating methods include hot air reflow and infrared reflow. The heating method may be to heat the entire surface or to heat localized areas. The heating temperature may be, for example, within the range of 240 to 280°C.

When semiconductor elements are stacked in multiple layers, the heat history during wire bonding and other processes increases, and the impact of air bubbles present at the interface between the film-like adhesive and the semiconductor elements on peeling can be significant. However, the film-like adhesive of this embodiment uses a specific acrylic rubber, which tends to reduce cohesive force and improve embeddability. As a result, air bubbles are less likely to become trapped within the semiconductor device, and the air bubbles can be easily diffused during the sealing process, preventing peeling due to air bubbles at the adhesive interface.

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

[Preparation of film-like adhesive]
Examples and Comparative Examples
<Preparation of adhesive varnish>
Cyclohexanone was added to a composition consisting of (A) epoxy resin as a thermosetting resin, (B) phenolic resin as a curing agent, and (D) inorganic filler, with the product names and composition ratios (unit: parts by mass) shown in Tables 1 and 2, and stirred and mixed. (C) acrylic rubber shown in Tables 1 and 2 was added to this and stirred, and (E) coupling agent and (F) curing accelerator shown in Tables 1 and 2 were further added and stirred until each component was uniform, to prepare an adhesive varnish. The numerical values of (C) component and (D) component shown in Tables 1 and 2 refer to parts by mass of solid content.

(A) Thermosetting Resin (A1) YDCN-700-10 (trade name, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., o-cresol novolac type epoxy resin, epoxy equivalent: 209 g/eq)

(B) Curing agent (B1) HE-100C-30 (trade name, manufactured by Air Water Inc., phenylaralkyl type phenolic resin, hydroxyl group equivalent: 174 g/eq, softening point 77° C.)

(C) Acrylic Rubber (C1) Improved SG-P3 (SG-P3 (product name, manufactured by Nagase ChemteX Corporation) acrylic rubber from which the structural units derived from acrylonitrile have been removed, weight average molecular weight of acrylic rubber: 600,000, theoretical Tg of acrylic rubber: 12° C., P _CN /P _CO =0.001)
(C2) SG-P3 solvent-change product (SG-P3 (product name, Nagase ChemteX Corporation, acrylic rubber methyl ethyl ketone solution) with a changed solvent, acrylic rubber weight average molecular weight: 800,000, acrylic rubber theoretical Tg: 12° C., P _CN /P _CO =0.070)

(Measurement of IR spectrum)
The P _CN /P _CO of (C1) and (C2) was calculated by the following method. First, the solvent was removed from (C1) and (C2), and the transmission IR spectrum of the product was measured by the KBr tablet method, and the vertical axis was the absorbance and the horizontal axis was the wave number (cm ^-1 ). The IR spectrum was measured using an FT-IR6300 (manufactured by JASCO Corporation, light source: high brightness ceramic light source, detector: DLATGS).

(Height of absorption peak due to stretching vibration of carbonyl group P _CO )
The peak with the highest absorbance between the two points of 1670 cm ^-1 and 1860 cm ^-1 was taken as the peak point. The straight line between the two points of 1670 cm ^-1 and 1860 cm ^-1 was taken as the baseline, the point on this baseline with the same wavenumber as the peak point was taken as the baseline point, and the difference in absorbance between the baseline point and the peak point was taken as the height of the absorption peak derived from the stretching vibration of the carbonyl group (P _CO ).

(Peak height P _CN due to the stretching vibration of the nitrile group)
In the same IR spectrum as that used to determine _PCO , the peak with the highest absorbance between 2270 cm ^-1 and 2220 cm ^-1 was taken as the peak point. The straight line between 2270 ^{cm -1} and 2220 cm ^-1 was taken as the baseline, and the point on this baseline that had the same wavenumber as the peak point was taken as the baseline point, and the difference in absorbance between the baseline point and the peak point was taken as the height of the peak derived from the stretching vibration of the nitrile group (P _CN ).

(D) Inorganic filler (D1) SC2050-HLG (product name, manufactured by Admatechs Co., Ltd., silica filler dispersion, average particle size 0.50 μm)

(E) Coupling agent (E1) A-189 (trade name, manufactured by Nippon Unicar Co., Ltd., γ-mercaptopropyltrimethoxysilane)
(E2) A-1160 (product name, manufactured by Nippon Unicar Co., Ltd., γ-ureidopropyltriethoxysilane)

(F) Curing accelerator (F1) 2PZ-CN (trade name, manufactured by Shikoku Chemical Industry Co., Ltd., 1-cyanoethyl-2-phenylimidazole)

<Preparation of film adhesive>
The prepared adhesive varnish was filtered through a 100 mesh filter and vacuum degassed. A polyethylene terephthalate (PET) film with a thickness of 38 μm that had been subjected to a release treatment was prepared as a substrate film, and the adhesive varnish after vacuum degassing was applied onto the PET film. The applied adhesive varnish was heated and dried in two stages at 90° C. for 5 minutes and then at 130° C. for 5 minutes to obtain film-like adhesives of Examples 1-1 and 1-2 and Comparative Examples 1-1 and 1-2, as well as Examples 2-1, 2-2 and Comparative Examples 2-1 and 2-2 in a B-stage state. In the film-like adhesive, the thickness was adjusted to 10 μm depending on the amount of adhesive varnish applied.

[Measurement of copper ion permeation time]
<Preparation of Solution A>
2.0 g of anhydrous copper (II) sulfate was dissolved in 1,020 g of distilled water and stirred until the copper sulfate was completely dissolved, to prepare an aqueous solution of copper sulfate having a copper ion concentration of 500 mg/kg in terms of Cu element. The resulting aqueous solution of copper sulfate was designated as Solution A.

<Preparation of Solution B>
1.0 g of anhydrous sodium sulfate was dissolved in 1000 g of distilled water and stirred until sodium sulfate was completely dissolved. 1000 g of N-methyl-2-pyrrolidone (NMP) was further added to the mixture and stirred. After that, the mixture was air-cooled to room temperature to obtain an aqueous sodium sulfate solution. The resulting solution was designated as Liquid B.

<Measurement of copper ion permeation time>
The film-like adhesives (thickness: 10 μm) of Examples 1-1, 1-2, Comparative Example 1-2, and Examples 2-1, 2-2, and Comparative Example 2-2 prepared above were each cut into a circle with a diameter of about 3 cm. Next, two silicon packing sheets with a thickness of 1.5 mm, an outer diameter of about 3 cm, and an inner diameter of 1.8 cm were prepared. The film-like adhesives cut into circles were sandwiched between two silicon packing sheets, which were then sandwiched between the flanges of two glass cells with a volume of 50 mL and fixed with rubber bands.

Next, 50 g of solution A was poured into one glass cell, and then 50 g of solution B was poured into the other glass cell. A carbon electrode, Mars Carbon (Staedtler LLC, φ2 mm/130 mm), was inserted into each cell. The anode was connected to a DC power source (DC power supply AD-9723D, A&D Co., Ltd.), with the solution A side as the anode and the solution B side as the cathode. The cathode and the DC power source were also connected in series via an ammeter (Digital multimeter PC-720M, Sanwa Electric Instruments Co., Ltd.). A voltage of 24.0 V was applied at room temperature, and measurement of the current value was started after the application. The measurement was continued until the current value exceeded 15 μA, and the time when the current value reached 10 μA was defined as the copper ion permeation time. The results are shown in Tables 3 and 4. In this evaluation, the longer the permeation time, the more the copper ion permeation was suppressed.

[Appearance evaluation of coated surface]
The appearance of the coated surface of the film-like adhesives of Examples 1-1 and 1-2, Comparative Example 1-2, and Examples 2-1, 2-2, and Comparative Example 2-2 was evaluated visually to check for the presence of foreign matter, voids, streaks, etc. Those in which no foreign matter, voids, streaks, etc. were found were rated "A", those in which foreign matter, voids, streaks, etc. were found were rated "B", and those in which a large amount of foreign matter, voids, streaks, etc. were found were rated "C". The results are shown in Tables 3 and 4.

[Evaluation of Adhesion Strength]
<Fabrication of Semiconductor Device>
A dicing tape (manufactured by Hitachi Chemical Co., Ltd., thickness 110 μm) was prepared, and the film-like adhesives (thickness 10 μm) prepared in Examples 1-1, 1-2, and Comparative Example 1-1, as well as Examples 2-1, 2-2, and Comparative Example 2-1 were attached to prepare a dicing-die bonding integrated adhesive sheet comprising a dicing tape and a film-like adhesive. A 400 μm thick semiconductor wafer was laminated on the film-like adhesive side of the dicing-die bonding integrated adhesive sheet at a stage temperature of 70° C. to prepare a dicing sample.

The obtained diced sample was cut using a fully automatic dicer DFD-6361 (manufactured by Disco Corporation). Cutting was performed using a step-cut method with two blades, and dicing blades ZH05-SD3500-N1-xx-DD and ZH05-SD4000-N1-xx-BB (both manufactured by Disco Corporation) were used. The cutting conditions were blade rotation speed 4000 rpm, cutting speed 50 mm/sec, and chip size 7.5 mm x 7.5 mm. The first cutting step was performed so that about 30 μm of the semiconductor wafer remained, and then the second cutting step was performed so that about 20 μm of cut was made in the dicing tape.

Then, the semiconductor chip obtained by cutting was thermocompression bonded onto a solder resist (Taiyo Holdings Co., Ltd., product name: AUS-308). The bonding conditions were a temperature of 120°C, a time of 1 second, and a pressure of 0.1 MPa. The sample obtained by bonding was then placed in a dryer and cured at 170°C for 1 hour. The semiconductor chip bonded to the solder resist was cured, and the die shear strength after curing between the semiconductor chip and the solder resist was measured by hooking and pulling the semiconductor chip with a universal bond tester (manufactured by Nordson Advanced Technology Co., Ltd., product name: Series 4000), and evaluated as the adhesive strength. The measurement conditions were a stage temperature of 250°C. The results are shown in Tables 5 and 6.

As shown in Tables 5 and 6, film adhesives with an inorganic filler content of 0.5 to 10 parts by mass per 100 parts by mass of the total mass of the thermosetting resin, curing agent, acrylic rubber, and inorganic filler had a longer copper ion permeation time and superior adhesive strength compared to film adhesives that did not meet this requirement.

As described above, it has been confirmed that the film-like adhesive of the present invention sufficiently suppresses copper ion permeation within the adhesive while also exhibiting excellent adhesive strength.

1...film-like adhesive, 2...substrate, 3...cover film, 6...adhesive layer, 7...dicing tape, 9, 9a, 9b...semiconductor element, 10...support member, 11...wire, 12...sealant, 13...terminal, 100, 110, 120, 130...adhesive sheet, 200, 210...semiconductor device.

Claims (2)

A support member;
a first semiconductor element adhered onto the support member by a first adhesive member;
a second semiconductor element bonded onto the first semiconductor element by a second adhesive member;
A semiconductor device having a stacked semiconductor element structure,
the first adhesive member and the second adhesive member are cured products of a film-like adhesive,
the film-like adhesive contains a thermosetting resin, a curing agent, an acrylic rubber, and an inorganic filler;
the content of the acrylic rubber is 60 to 85 parts by mass with respect to 100 parts by mass of the total mass of the thermosetting resin, the curing agent, the acrylic rubber, and the inorganic filler;
the content of the inorganic filler is 0.5 to 10 parts by mass with respect to 100 parts by mass of the total mass of the thermosetting resin, the curing agent, the acrylic rubber, and the inorganic filler;
The semiconductor device, wherein the thickness of the film-like adhesive is 15 μm or less. The semiconductor device according to claim 1, wherein the support member includes a member made of copper.

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