Dicing die-attach film and method for manufacturing semiconductor package

Abstract

Provided is a dicing die-attach film for use in a cool expansion step. In the dicing die-attach film, a die-attach film contains the following components (a)-(d): (a) an epoxy resin; (b) an epoxy resin curing agent; (c) a phenoxy resin and / or a polyurethane resin having a glass transition temperature of - 15°C to 70°C inclusive; and (d) an inorganic filler.

Description

Dicing Die Attach Film and Method for Manufacturing Semiconductor Package

[0001] The present invention relates to a dicing die attach film and a method for manufacturing a semiconductor package.

[0002] In the manufacturing process of a semiconductor device, a dicing die attach film (which is a film-shaped adhesive and also referred to as a dicing die bond film) having both the function of a dicing film for adhering and holding a semiconductor wafer in a dicing step and the function of a film-shaped adhesive for chip fixation required in a mounting step for a semiconductor chip obtained by dicing is known (see, for example, Patent Documents 1 to 3). This dicing die attach film has a laminated structure in which a die attach film (adhesive layer) is provided on a dicing film including a base film and a pressure-sensitive adhesive layer. A typical method of using the dicing die attach film is as follows. First, the die attach film side of the dicing die attach film is brought into close contact with the semiconductor wafer to hold the semiconductor wafer, and in this state, the semiconductor wafer is diced together with the die attach film with a blade. Next, by expanding (stretching) the dicing film, the semiconductor wafer is divided together with the die attach film into individual pieces. The obtained semiconductor chip is picked up together with the die attach film piece, and the semiconductor chip is fixed to an adherend such as a lead frame via the die attach film piece. A semiconductor package can be obtained through such steps.

[0003] In the above blade dicing, the dicing film and the die attach film may adhere to each other under the influence of heat generated during dicing. In addition, the generated cutting chips may adhere to the semiconductor chips or cause the chips to adhere to each other. Further, with the recent progress in thinning of semiconductor wafers, problems such as chipping have also become apparent. To make these problems less likely to occur, it is necessary to reduce the cutting speed, which imposes a restriction on the improvement of manufacturing efficiency.

[0004] Alternative dicing methods have also been proposed. For example, a method has been proposed in which a laser beam is irradiated onto the planned division lines of a semiconductor wafer fixed with a dicing film or dicing die-attach film to form a modified region, and then the film is expanded to break the semiconductor wafer along the planned division lines and obtain individual semiconductor chips (stealth dicing method) (see, for example, Patent Document 4). Another method has been proposed in which grooves that do not penetrate to the back surface are formed on the surface of the semiconductor wafer, and then the back surface is ground to divide it into individual semiconductor chips (Dicing Before Grinding; DBG) (see, for example, Patent Document 5). When a dicing die-attach film is applied to stealth dicing or DBG, the die-attach film must also be broken along with the semiconductor wafer during the expansion process. To improve the breakability of the die-attach film, expansion at low temperatures (cool expansion) is now being performed. Patent document 6 describes controlling the storage modulus, loss modulus, loss tangent, and glass transition temperature of the die attach film to predetermined levels in order to more reliably break the die attach film together with the semiconductor wafer by cool expand.

[0005] Japanese Patent Publication No. 6989721 Japanese Patent Publication No. 6935605 Japanese Patent Publication No. 6902641 International Publication No. 2019 / 008809 Japanese Patent Publication No. 2003-007649 Japanese Patent Publication No. 6068386

[0006] When performing cool expand using a dicing die attach film, it is necessary to increase the fluidity of the die attach film to some extent in order to achieve sufficient adhesion when bonding the semiconductor wafer and the dicing die attach film. If the glass transition temperature (Tg) of the polymer component (binder component) constituting the die attach film is, for example, 70°C or lower, bonding at a temperature of 70°C or higher can further improve the adhesion between the wafer and the die attach film. Furthermore, cool expand is performed at a sufficiently low temperature to improve the decoupling ability of the die attach film. If the Tg of the above polymer component is, for example, -15°C or higher, expanding at a temperature of -15°C or lower allows for decoupling while ensuring adhesion to the wafer while the polymer component is in the glass region, thereby improving the integrated decoupling ability between the wafer and the die attach film.

[0007] As described above, by using a polymer component in the die attach film with a Tg of -15°C to 70°C, sufficient adhesion can be obtained between the die attach film and the semiconductor wafer even when laminated at a relatively mild high temperature of around 70°C, and excellent separation properties of the die attach film can also be achieved during cool expand at a relatively mild low temperature of around -15°C. In fact, the specific embodiment described in Patent Document 6 uses a die attach film containing an acrylic resin with a Tg of -13°C, 4°C, or 12°C. However, as the inventors continued their investigations, they found that when the polymer component incorporated into the die attach film has a Tg within the range of -15°C to 70°C, and when this Tg is below the temperature at which it is laminated to the semiconductor wafer and above the temperature at which it is cool expanded, although the adhesion to the semiconductor wafer and the separation properties due to cool expand are good, the peel strength between the dicing film and the die attach film tends to increase during the pickup process, resulting in a certain percentage of pickup failures. This is thought to be because the die attach film contains polymer components with a relatively low Tg (temperature range of -15°C to 70°C), which makes it easier for the die attach film to bond firmly to the dicing film when bonding with a semiconductor wafer at temperatures above the Tg.

[0008] The present invention aims to provide a dicing die-attach film for use in a cool-expand process, wherein the die-attach film employs a polymer component with a Tg of -15°C to 70°C, thereby enabling bonding of the die-attach film and the semiconductor wafer in a relatively mild high-temperature range to sufficiently enhance their adhesion, and further enabling sufficiently enhanced integral separation of the semiconductor wafer and the die-attach film in a relatively mild low-temperature range during the subsequent cool-expand process, while also preventing excessive increases in adhesion between the dicing film and the die-attach film during bonding and effectively suppressing pickup defects. The present invention also aims to provide a method for manufacturing a semiconductor package using this dicing die-attach film.

[0009] In view of the above problems, the present inventors conducted extensive research and found that, when using a polymer component with a Tg in the range of -15°C ≤ Tg ≤ 70°C as the polymer component of the die attach film constituting the dicing die attach film, by applying at least one of phenoxy resin and polyurethane resin as the polymer species, adhesion to the semiconductor wafer can be sufficiently enhanced by laminating with the wafer in a relatively mild high-temperature range due to Tg ≤ 70°C, and good discontinuity can be achieved by cool expansion in a relatively mild low-temperature range due to -15°C ≤ Tg. Furthermore, excessive increase in adhesion between the dicing film and the die attach film is less likely to occur during lamination, and pickup defects can be sufficiently suppressed. The present invention was completed after further research based on these findings.

[0010] The above problems of the present invention are solved by the following means: [1] A dicing die attach film for use in a cool-expand process, wherein the die attach film of the dicing die attach film contains the following components (a) to (d): (a) epoxy resin; (b) epoxy resin curing agent; (c) phenoxy resin and / or polyurethane resin having a glass transition temperature of -15°C to 70°C; (d) inorganic filler. [2] The dicing die attach film according to [1], wherein the content of the inorganic filler (d) in the die attach film is 30 to 65 volume percent. [3] The dicing die attach film according to [1] or [2], wherein the linear expansion coefficient based on the expansion rate of the cured product of the die attach film in the range of 240 to 260°C is 140 ppm / K or less. [4] A dicing die attach film according to any one of [1] to [3], wherein when the die attach film is heated from 25°C at a heating rate of 5°C / min, the melt viscosity at 120°C is 10,000 Pa·s or less. [5] A dicing die attach film according to any one of [1] to [4], wherein the die shear adhesive strength of the cured die attach film is 20 MPa or more. [6] A dicing die attach film according to any one of [1] to [5], wherein the thermal conductivity of the cured die attach film is 0.4 W / m·K or more. [7] A method for manufacturing a semiconductor package, comprising the steps of: stealth dicing a semiconductor wafer while the dicing die attach film according to any one of [1] to [6] is bonded to the semiconductor wafer; separating the semiconductor wafer integrally with the die attach film by cool expand; and picking up the separated semiconductor chip together with the die attach film piece and thermocompressing it onto a wiring board.[8] A method for manufacturing a semiconductor package, comprising the steps of: stealth dicing a semiconductor wafer; bonding a dicing die-attach film described in any of [1] to [6] to the semiconductor wafer after stealth dicing; separating the semiconductor wafer integrally with the die-attach film by cool-expanding; and picking up the separated semiconductor chips together with the die-attach film pieces and thermocompressing them onto a wiring substrate. [9] A method for manufacturing a semiconductor package, comprising the steps of: forming grooves on the surface of a semiconductor wafer that do not penetrate to the back surface, and then separating the semiconductor chips by grinding the back surface; bonding a dicing die-attach film described in any of [1] to [6] to the back surface; separating the die-attach film integrally with the semiconductor chips by cool-expanding; and picking up the semiconductor chips together with the die-attach film pieces and thermocompressing them onto a wiring substrate.

[0011] In this invention, a numerical range represented using "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0012] The dicing die attach film for use in the cool-expand process of the present invention employs a polymer component with a Tg of -15°C to 70°C as the die attach film. This makes it possible to bond the die attach film and the semiconductor wafer in a relatively mild high-temperature range to sufficiently enhance their adhesion, and also to sufficiently enhance the integral separation of the semiconductor wafer and the die attach film in a relatively mild low-temperature range during the subsequent cool-expand process. Furthermore, it makes it less likely for the adhesion between the dicing film and the die attach film to increase excessively during the bonding process, effectively suppressing pickup failures. According to the semiconductor chip manufacturing method of the present invention, each of the processes of bonding the semiconductor wafer and the dicing die attach film, separating the semiconductor wafer by cool-expand, and picking up the semiconductor chip obtained by this separation and mounting it on a wiring board can be performed with high precision under relatively mild temperature conditions.

[0013] [Dicing Die Attach Film] The dicing die attach film of the present invention is a dicing die attach film suitable for application in the cool expand process. That is, in one embodiment, when a semiconductor wafer is stealth diced with the dicing die attach film bonded to it, or when the semiconductor wafer is stealth diced and then the dicing die attach film is bonded to the semiconductor wafer, and then the semiconductor wafer is integrally separated from the die attach film by cool expand, and the separated semiconductor chips are picked up together with the die attach film pieces and thermocompressed onto a wiring board to obtain a semiconductor package, the dicing die attach film of the present invention can be used as the dicing die attach film. In another embodiment, a semiconductor package is obtained by forming grooves on the surface of a semiconductor wafer that do not penetrate to the back surface, then grinding the back surface to separate it into individual semiconductor chips, then laminating a dicing die attach film to the back surface, separating the die attach film together with the semiconductor chips by cool expand, and then picking up the semiconductor chips together with the die attach film pieces and thermocompressing them onto a wiring substrate. In this process, the dicing die attach film of the present invention can be used as the dicing die attach film.

[0014] The dicing die-attach film of the present invention is a film having a structure in which a die-attach film (adhesive layer) is provided on the adhesive layer of a dicing film, which is a laminate of a base film and an adhesive layer. The dicing die-attach film of the present invention is characterized by the component composition of the die-attach film (particularly the combination of Tg and type of polymer component that functions as a binder). Due to these characteristics, it is possible to achieve a state in which the semiconductor wafer and the dicing die-attach film of the present invention are firmly adhered in a relatively mild high-temperature range, and in that state, by employing a relatively mild low-temperature cool expand (low-temperature expansion for integrally separating the semiconductor chip and the die-attach film) as the expand process, it is possible to achieve excellent separation and subsequent excellent pick-up performance. The form of the dicing film constituting the dicing die-attach film of the present invention is not particularly limited, and ordinary dicing films applicable to dicing die-attach films can be used. Among the dicing die-attach films of the present invention, preferred forms of the die-attach film characteristic of the present invention are described below.

[0015] <Component Composition of Die Attach Film> The dicing die attach film of the present invention comprises the following components (a) to (d): (a) epoxy resin; (b) epoxy resin curing agent; (c) phenoxy resin and / or polyurethane resin having a glass transition temperature of -15°C or higher and 70°C or lower; (d) inorganic filler. In addition to the following components (a) to (d), the die attach film used in the present invention may also contain other components described later, to the extent that they do not impair the effects of the present invention.

[0016] (a) Epoxy resin: The epoxy resin is a thermosetting resin having epoxy groups, and its epoxy equivalent is 500 g / eq or less. The epoxy resin may be liquid, solid, or semi-solid. In the present invention, liquid means having a softening point of 25°C or less, solid means having a softening point of 60°C or more, and semi-solid means having a softening point between the softening point of the liquid and the softening point of the solid (greater than 25°C and less than 60°C). As for the epoxy resin used in the present invention, it is preferable that the softening point is 100°C or less from the viewpoint of obtaining a die attach film that can reach a low melt viscosity in a suitable temperature range (for example, 60 to 120°C). In the present invention, the softening point is the value measured by the softening point test (ring ball type) method (measurement conditions: in accordance with JIS-K7234:1986).

[0017] In the epoxy resin described above, the epoxy equivalent is preferably 150 to 450 g / eq from the viewpoint of increasing the crosslinking density of the thermosetting body. In this invention, epoxy equivalent refers to the number of grams (g / eq) of resin containing 1 gram equivalent of epoxy groups. The weight-average molecular weight of the epoxy resin is preferably less than 10,000, and more preferably 5,000 or less. There is no particular limit on the lower limit, but 300 or more is practical. The method for measuring the weight-average molecular weight will be described later.

[0018] Examples of epoxy resin skeletons include phenol novolac type, orthocresol novolac type, cresol novolac type, dicyclopentadiene type, biphenyl type, fluorenebisphenol type, triazine type, naphthol type, naphthalenediol type, triphenylmethane type, tetraphenyl type, bisphenol A type, bisphenol F type, bisphenol AD ​​type, bisphenol S type, and trimethylolmethane type. Of these, triphenylmethane type, bisphenol A type, cresol novolac type, and orthocresol novolac type are preferred from the viewpoint of obtaining a die-attach film with low resin crystallinity and a good appearance.

[0019] In the die attach film used in the present invention, the epoxy resin content is preferably 3 to 70% by mass, more preferably 5 to 50% by mass, even more preferably 10 to 40% by mass, and also preferably 12 to 30% by mass.

[0020] (b) Epoxy resin curing agent: Any curing agent such as amines, acid anhydrides, and polyhydric phenols can be used as the epoxy resin curing agent (in this invention, when simply referred to as "epoxy resin curing agent" or "curing agent," it encompasses both the epoxy resin curing agent and the curing accelerator (curing catalyst)). In this invention, it is preferable to use a latent curing agent from the viewpoint of producing a die-attach film with low melt viscosity, curability at high temperatures above a certain temperature, rapid curing properties, and high storage stability that allows for long-term storage at room temperature. Examples of latent curing agents include dicyandiamide compounds, imidazole compounds, curing catalyst complex polyhydric phenol compounds, hydrazide compounds, boron trifluoride-amine complexes, amineimide compounds, polyamine salts, and modified or microencapsulated forms thereof. These may be used individually or in combination of two or more. From the viewpoint of having better latent properties (excellent stability at room temperature and the property of exhibiting curability upon heating) and a faster curing speed, it is more preferable to use imidazole compounds.

[0021] The amount of epoxy resin curing agent in the die attach film can be appropriately set depending on the type of curing agent and the reaction mode. For example, it can be 0.5 to 100 parts by mass per 100 parts by mass of epoxy resin, 1 to 80 parts by mass, 2 to 50 parts by mass, and preferably 4 to 20 parts by mass. Furthermore, when an imidazole compound is used as the epoxy resin curing agent, it is preferable to use 0.5 to 10 parts by mass of the imidazole compound per 100 parts by mass of epoxy resin, and more preferably 2 to 9 parts by mass. By setting the content of the epoxy resin curing agent above the preferred lower limit, the curing time can be shortened, while by setting it below the preferred upper limit, the residue of excess curing agent in the die attach film can be suppressed. As a result, the adsorption of moisture by the residual curing agent is suppressed, and the reliability of the semiconductor device can be further improved.

[0022] (c) Phenoxy resin and / or polyurethane resin having a glass transition temperature of -15°C or higher and 70°C or lower: Component (c) is a so-called polymer component and functions as a binder for the die attach film. The die attach film used in the present invention uses a polymer with a glass transition temperature (Tg) of -15°C or higher and 70°C or lower as this polymer component, and employs at least one of phenoxy resin and polyurethane resin as this polymer type, rather than acrylic resin or the like which are commonly used as polymer components.

[0023] By setting the Tg of the polymer component to -15°C or higher, if cool expansion is performed at, for example, -15°C or lower, the polymer component will be in the glass region rather than the rubber region, allowing for integral separation of the semiconductor wafer and the die attach film while ensuring adhesion between the semiconductor wafer and the die attach film. In order to make the polymer component glassy in this cool expansion, the cool expansion should be performed at or below the Tg of the polymer component. Therefore, in this invention, the temperature of cool expansion is not limited to the low temperature range of -15°C or lower, but can be appropriately set according to the Tg of the polymer component. In this invention, the temperature of cool expansion is preferably "Tg - 2°C" or lower, more preferably "Tg - 4°C" or lower, even more preferably "Tg - 8°C" or lower, and even more preferably "Tg - 16°C" or lower. This temperature depends on the Tg of the polymer component, but is preferably -50 to 20°C, more preferably -40 to 10°C, even more preferably -30 to 5°C, and even more preferably -25 to 0°C. -20 to -5°C is more preferable, and -17 to -8°C is even more preferable. Furthermore, by setting the Tg of the polymer component to 70°C or lower, if the temperature at which the dicing die attach film is bonded to the semiconductor wafer is, for example, 70°C or higher, the die attach film can be bonded to the semiconductor wafer in a fluid state, thereby further improving adhesion. This improvement in adhesion can be achieved by performing the bonding at or above the Tg of the polymer component. Therefore, in the present invention, the bonding temperature is not limited to a high temperature range of 70°C or higher, but can be appropriately set according to the Tg of the polymer component. The bonding temperature is preferably above the Tg of the polymer component, but may also be above Tg + 2°C, above Tg + 4°C, above Tg + 8°C, above Tg + 16°C, or above Tg + 32°C. The bonding temperature depends on the Tg of the polymer component, but a relatively mild high temperature range of 40 to 80°C is preferred, 50 to 75°C is more preferred, 55 to 75°C is even more preferred, and 60 to 72°C is also preferred.The Tg of the above polymer component is preferably -10 to 70°C, more preferably -5 to 70°C, even more preferably 0 to 70°C, even more preferably 5 to 70°C, even more preferably 10 to 70°C, also preferably 11 to 60°C, also preferably 12 to 50°C, and also preferably 12 to 40°C.

[0024] The Tg of the above polymer component is the peak-top temperature of tanδ in dynamic viscoelasticity measurement. Specifically, Tg can be determined as follows: A solution obtained by dissolving the polymer is applied to a release film, heated and dried to form a polymer film on the release film. The release film is peeled off and removed from this polymer film, and this polymer film is measured using a dynamic viscoelasticity measuring device (product name: Rheogel-E4000F, manufactured by UBM) under the conditions of a measurement temperature range of 20 to 300°C, a heating rate of 5°C / min, and a frequency of 1 Hz. The obtained peak-top temperature of tanδ (the temperature at which tanδ shows a maximum) is defined as Tg.

[0025] The weight-average molecular weight of the polymer component is preferably 10,000 or more. There is no particular upper limit, but 5,000,000 or less is practical. In this invention, the weight-average molecular weight is the value obtained by GPC (Gel Permeation Chromatography) on a polystyrene basis.

[0026] The content of component (c), which is the polymer component described above, in the die attach film used in the present invention is preferably 1 to 40 parts by mass, more preferably 5 to 35 parts by mass, even more preferably 10 to 35 parts by mass, even more preferably 15 to 32 parts by mass, and even more preferably 20 to 30 parts by mass, per 100 parts by mass of the epoxy resin.

[0027] The polymer species of the polymer component described above is at least one of phenoxy resin and polyurethane resin. By using at least one of phenoxy resin and polyurethane resin, it is possible to prevent the dicing film and die attach film from becoming too tightly bonded when laminated to the semiconductor wafer, even when the Tg is in the low Tg region. As a result, pickup defects are less likely to occur in the pickup process after cool expansion.

[0028] Phenoxy resins are preferred because they have good compatibility with epoxy resins due to their similar structure. Phenoxy resins can be obtained by conventional methods. For example, they can be obtained by the reaction of bisphenol or a biphenol compound with an epihalohydrin such as epichlorohydrin, or by the reaction of a liquid epoxy resin with bisphenol or a biphenol compound. The amount of epoxy groups remaining in the phenoxy resin is preferably 5000 g / eq or more in terms of epoxy equivalents. In this invention, the epoxy resin, which is component (a), and the phenoxy resin, which is component (c), both have epoxy groups. However, in this invention, resins with an epoxy equivalent of 500 g / eq or less are classified as component (a), and those that do not fall under this category are classified as component (c).

[0029] Polyurethane resin is a polymer having urethane (carbamic acid ester) bonds in its main chain, and is also called urethane resin. Polyurethane resin has structural units derived from polyols and structural units derived from polyisocyanates, and may also have structural units derived from polycarboxylic acids. Polyurethane resin may be used alone or in combination of two or more types. Polyurethane resin can be synthesized by conventional methods and is also available from the market. Examples of commercially available polyurethane resins that can be used include UR-3500 (manufactured by Toyobo MC Co., Ltd.).

[0030] (d) Inorganic filler: The inorganic filler can be any inorganic filler that is commonly used in die attach films, without any particular limitations. Examples include various inorganic powders such as silica, clay, gypsum, calcium carbonate, barium sulfate, alumina (aluminum oxide), beryllium oxide, magnesium oxide, silicon carbide, silicon nitride, aluminum nitride, boron nitride, and other ceramics; metals or alloys such as aluminum, copper, silver, gold, nickel, chromium, lead, tin, zinc, palladium, and solder; and carbons such as carbon nanotubes, carbon nanofibers, and graphene.

[0031] From the viewpoint of more efficiently releasing heat from within the semiconductor package to the outside, the thermal conductivity of the inorganic filler is preferably 12 W / m·K or higher, more preferably 20 W / m·K or higher, and even more preferably 30 W / m·K or higher. This thermal conductivity refers to the thermal conductivity at 25°C, and literature values ​​for each material can be used. Even if there is no literature description, for example, values ​​measured according to JIS R 1611:2010 for ceramics and values ​​measured according to JIS H 7801:2005 for metals can be used as substitutes. For example, alumina particles (thermal conductivity: 36 W / m·K), aluminum nitride particles (thermal conductivity: 150-290 W / m·K), boron nitride particles (thermal conductivity: 60 W / m·K), zinc oxide particles (thermal conductivity: 54 W / m·K), silicon nitride particles (thermal conductivity: 27 W / m·K), silicon carbide particles (thermal conductivity: 200 W / m·K), and magnesium oxide particles (thermal conductivity: 59 W / m·K) are preferred inorganic fillers used in the present invention. Furthermore, metal particles having higher thermal conductivity than ceramics, or particles surface-coated with metal, such as single metal fillers like silver (thermal conductivity: 429 W / m·K), nickel (thermal conductivity: 91 W / m·K), and gold (thermal conductivity: 329 W / m·K), as well as polymer particles such as acrylic and silicone resins surface-coated with these metals, are also preferred inorganic fillers used in the present invention.

[0032] The average particle size (d50) of the inorganic filler described above is not particularly limited, but from the viewpoint of thinning the die attach film, it is preferably 0.01 to 6.0 μm, preferably 0.01 to 5.0 μm, more preferably 0.1 to 3.5 μm, and even more preferably 0.2 to 3.0 μm. In the present invention, the average particle size (d50) is the so-called median diameter, and is the particle size at which the cumulative distribution reaches 50% when the total volume of the particles is taken as 100% in the cumulative distribution, measured by laser diffraction and scattering methods.

[0033] The Mohs hardness of the above inorganic filler is not particularly limited, but is preferably 2 or higher, and more preferably 2 to 9. The Mohs hardness can be measured using a Mohs hardness tester.

[0034] The inorganic fillers described above may be surface-treated or surface-modified. Examples of surface treatment agents used for such surface treatment or modification include silane coupling agents, phosphoric acid or phosphoric acid compounds, and surfactants. For example, one can refer to the descriptions of silane coupling agents, phosphoric acid or phosphoric acid compounds, and surfactants in the section on thermal conductive fillers in International Publication No. 2018 / 203527 or the section on aluminum nitride fillers in International Publication No. 2017 / 158994.

[0035] The inorganic filler can take the form of flakes, needles, filaments, spheres, or scales. Spherical particles are preferred from the viewpoint of high packing capacity and fluidity.

[0036] In the die attach film used in the present invention, the content of the inorganic filler is preferably 20 to 70% by volume, and more preferably 30 to 65% by volume. The content (by volume) of the inorganic filler can be calculated from the mass and specific gravity of each component contained in the die attach film.

[0037] Other components: The die-attach film used in the present invention may also preferably contain a silane coupling agent. This silane coupling agent does not include the silane coupling agent used in the surface treatment of the inorganic filler (the silane coupling agent already bonded or adsorbed on the surface of the inorganic filler to be blended). A silane coupling agent is a silicon atom to which at least one hydrolyzable group such as an alkoxy group or an aryloxy group is bonded, and in addition thereto, alkyl groups, alkenyl groups, aryl groups, etc. are also bonded. The alkyl group is preferably one which has an amino group, alkoxy group, epoxy group or (meth)acryloyloxy group as a substituent, more preferably one which has an amino group (preferably a phenylamino group), an alkoxy group (preferably a glycidyloxy group) or a (meth)acryloyloxy group as a substituent, and particularly preferably one which has an amino group as a substituent. Examples of silane coupling agents include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, vinyltrimethoxysilane, and the like.

[0038] When the die attach film used in the present invention contains a silane coupling agent, the content of the silane coupling agent in the die attach film is preferably 0.2 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, even more preferably 1 to 6 parts by mass, and even more preferably 2 to 4 parts by mass, per 100 parts by mass of the epoxy resin.

[0039] The die attach film used in the present invention may further contain, within a range that does not impair the effects of the present invention, an ion trap agent (ion scavenger), a curing catalyst, a viscosity modifier, an antioxidant, a flame retardant, a colorant, a polymer other than the above component (c), and the like. For example, other additives described in International Publication No. WO 2017 / 158994 may be included.

[0040] The total proportion of the contents of each of the above components (a) to (d) in the die attach film used in the present invention can be, for example, 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and can also be 90% by mass or more. Further, the above proportion may be 100% by mass, and may also be 95% by mass or less.

[0041] The thickness of the die attach film used in the present invention is preferably 1.0 to 50.0 µm, more preferably 2.0 to 40.0 µm, and still more preferably 5.0 to 30.0 µm. This thickness can be measured by a contact linear gauge method (desktop contact-type thickness measuring device). The above die attach film is in a state before curing, that is, in a B-stage state.

[0042] <Characteristics of Die Attach Film> Coefficient of linear expansion: The die attach film preferably has a coefficient of linear expansion based on the expansion rate of its cured product in the range of 240 to 260°C of 140 ppm / K or less. Since the coefficient of linear expansion at a temperature not lower than Tg of the cured product is 140 ppm / K or less, stable adhesive force can be maintained even when the semiconductor package is exposed to high heat. This coefficient of linear expansion is usually 30 to 140 ppm / K, 40 to 140 ppm / K is practical, and 50 to 135 ppm / K is also preferred. The coefficient of linear expansion of the cured product of the die attach film can be determined by the method described in the Examples section of the present specification. In the present invention, when describing the characteristics of the die attach film, the term "cured product" refers to a cured product obtained by subjecting the die attach film to a thermosetting treatment at 180°C for 1 hour, or a cured product in an equivalent cured state.

[0043] Melt viscosity: When the die attach film is heated from 25°C at a heating rate of 5°C / min, the melt viscosity at 120°C is preferably 10000 Pa·s or less. The melt viscosity is more preferably 50 to 10000 Pa·s, still more preferably 100 to 9000 Pa·s, still more preferably 200 to 8000 Pa·s, and is also preferably 250 to 6000 Pa·s. This melt viscosity can be determined by the method described in the examples mentioned later.

[0044] Die shear adhesive strength: The die shear adhesive strength of a cured product of the die attach film is preferably 18 MPa or more, and more preferably 20 MPa or more. Higher die shear adhesive strength enables more stable maintenance of the adhesion state of a semiconductor chip to an adherend. This die shear adhesive strength can be determined by the method described in the examples mentioned later.

[0045] Thermal conductivity: The thermal conductivity of a cured product of the die attach film is preferably 0.3 W / m·K or more, and more preferably 0.4 W / m·K or more. The thermal conductivity is preferably 0.5 to 50 W / m·K, more preferably 0.6 to 40 W / m·K, still more preferably 0.8 to 35 W / m·K, and is also preferably 1.0 to 30 W / m·K. This thermal conductivity is bulk thermal conductivity determined by the method described in the examples mentioned later.

[0046] <Preparation of Die Attach Film> The die attach film can be formed by preparing a varnish containing each component constituting the die attach film, applying the varnish onto a release-treated substrate, and drying as needed. The varnish usually contains an organic solvent. Known methods can be appropriately employed for the application method, for example, application can be performed using a roll knife coater, gravure coater, die coater, reverse coater, or the like. The drying only needs to remove the organic solvent from the varnish to form a film without curing the epoxy resin, and can be performed, for example, by holding at a temperature of 80 to 150°C for 1 to 20 minutes.

[0047] The dicing die-attach film of the present invention can be prepared using the die-attach film described above. That is, the dicing die-attach film of the present invention can be obtained by laminating the die-attach film onto the surface of the adhesive layer of a laminate (dicing film) consisting of a base film and an adhesive layer in a conventional manner. The dicing film and the method for preparing the dicing die-attach film are known, and the dicing die-attach film of the present invention can be obtained by employing general methods, except that the component composition of the die-attach film is specified in the present invention. In addition, the dicing die-attach film can also be formed on the surface of a semiconductor wafer or the like by first laminating the die-attach film onto the surface of the die-attach film and then laminating the adhesive layer side of the dicing film onto the surface of the die-attach film.

[0048] The dicing die attach film of the present invention may be in the form of a film cut to an appropriate size, or it may be in the form of a film wound into a roll.

[0049] The dicing die attach film of the present invention is preferably stored under temperature conditions of 10°C or lower before use (before the curing reaction) from the viewpoint of suppressing the hardening of the epoxy resin in the die attach film before use.

[0050] [Method for Manufacturing Semiconductor Packages] In one embodiment, the method for manufacturing semiconductor packages of the present invention includes the steps of: stealth dicing a semiconductor wafer while the dicing die-attach film of the present invention and the semiconductor wafer are bonded together (step-1A); separating the semiconductor wafer integrally with the die-attach film by cool-expanding (step-2A); and picking up the separated semiconductor chips together with the die-attach film pieces and thermocompressing them onto a wiring substrate (step-3A).

[0051] In step 1A above, the state in which the dicing die attach film of the present invention and the semiconductor wafer are bonded is preferably such that the dicing die attach film of the present invention and the semiconductor wafer are bonded at a relatively mild high temperature range that is above the Tg of the polymer component of component (c) constituting the die attach film. The bonding temperature (bonding temperature) can be above the "Tg" of the polymer component, and may be "Tg + 2°C" or higher, "Tg + 4°C" or higher, "Tg + 8°C" or higher, "Tg + 16°C" or higher, or "Tg + 32°C" or higher. This bonding temperature depends on the Tg of the polymer component, but is preferably 40 to 80°C, more preferably 50 to 75°C, even more preferably 55 to 75°C, and also preferably 60 to 72°C. The stealth dicing method in step 1A above is known, and a conventional method can be applied with appropriate design modifications as needed.

[0052] In step 2A described above, the temperature of the cool expander is preferably lower than the Tg of the polymer component of component (c) constituting the die attach film. The temperature in the cool expander step is preferably "Tg - 2°C" or lower, more preferably "Tg - 4°C" or lower, even more preferably "Tg - 8°C" or lower, and even more preferably "Tg - 16°C" or lower. This temperature depends on the Tg of the polymer component, but is preferably -50 to 20°C, more preferably -40 to 10°C, even more preferably -30 to 5°C, and even more preferably -25 to 0°C. Even more preferably -20 to -5°C, and even more preferably -17 to -8°C. The cool expander method itself is well known, and a conventional method can be applied with appropriate design modifications as needed.

[0053] The semiconductor chip pickup in step 3A above is usually performed at room temperature (15 to 30°C). The pickup method itself is well known, and the usual method can be applied with appropriate design modifications as needed. In the manufacturing method of the present invention, the Tg of the polymer component of component (c) constituting the die attach film is within a predetermined low range (-15°C ≤ Tg ≤ 70°C), but because phenoxy resin or polyurethane resin is used as the polymer type, even if the bonding with the semiconductor wafer is performed at a temperature above the Tg of the polymer component, the adhesion between the semiconductor and the dicing film does not become excessively strong. As a result, pickup defects can be effectively suppressed. In step 3A above, the picked-up semiconductor chip is thermocompressed onto the wiring board via a die attach film piece. The conditions for this thermocompression can be, for example, a temperature of 100 to 150°C and a pressure of 0.2 to 2.0 MPa. A few seconds (for example, 1 to 10 seconds) is sufficient for thermocompression. As the above-mentioned wiring board, a substrate on which a semiconductor circuit is formed on its surface can be used as appropriate. Examples include printed circuit boards (PCBs), various lead frames, and substrates on which electronic components such as resistors and capacitors are mounted on the substrate surface.

[0054] The process from the above-mentioned thermocompression bonding to obtaining the semiconductor package can employ a general method. That is, the semiconductor chip is firmly bonded to the wiring substrate by thermocuring the die attach film piece, and then the substrate and semiconductor chip are connected, for example, via bonding wires, and further sealed with a sealing resin to obtain the semiconductor package. The thermocuring temperature can be, for example, 100 to 180°C, preferably 120 to 160°C, for about 10 to 120 minutes.

[0055] In another embodiment, the method for manufacturing a semiconductor package of the present invention includes the steps of: stealth dicing a semiconductor wafer (step-1B); bonding the dicing die-attach film of the present invention to the semiconductor wafer after stealth dicing (step-2B); integrally separating the semiconductor wafer from the die-attach film by cool-expanding (step-3B); and picking up the separated semiconductor chips together with the die-attach film pieces and thermocompressing them onto a wiring substrate (step-4B).

[0056] The stealth dicing method in step-1B described above is publicly known, and a conventional method can be applied with appropriate design modifications as needed.

[0057] The above step-2B preferably involves laminating the dicing die attach film of the present invention with the semiconductor wafer after stealth dicing at a relatively mild high temperature range that is above the Tg of the polymer component of component (c) constituting the die attach film. The lamination temperature may be above "Tg + 2°C", above "Tg + 4°C", above "Tg + 8°C", above "Tg + 16°C", or above "Tg + 32°C". This lamination temperature depends on the Tg of the polymer component, but is preferably 40 to 80°C, more preferably 50 to 75°C, even more preferably 55 to 75°C, and also preferably 60 to 72°C.

[0058] Step 3B is the same as step 2A, and the preferred configuration is also the same. Step 4B is the same as step 3A, and the preferred configuration is also the same. Furthermore, the process from thermocompression bonding in step 4B to obtaining the semiconductor package can employ a general method as described above.

[0059] In yet another embodiment, the method for manufacturing a semiconductor package of the present invention includes the steps of: forming grooves on the surface of a semiconductor wafer that do not penetrate to the back surface, and then dividing it into individual semiconductor chips by grinding the back surface (step-1C); laminating the dicing die attach film of the present invention to the back surface (step-2C); dividing the die attach film together with the semiconductor chips by cool expanding (step-3C); and picking up the divided semiconductor chips together with the die attach film pieces and thermocompressing them onto a wiring substrate (step-4C).

[0060] Step 1C described above is so-called DBG and subsequent back grinding, and this method itself is well known and can be applied by modifying the design as needed.

[0061] In step 2C described above, it is preferable that the back surface after grinding the back surface is laminated at a relatively mild high temperature range at or above the Tg of the polymer component of component (c) constituting the die attach film of the present invention. The lamination temperature (lamination temperature) may be "Tg + 2°C" or higher, "Tg + 4°C" or higher, "Tg + 8°C" or higher, "Tg + 16°C" or higher, or "Tg + 32°C" or higher. This lamination temperature depends on the Tg of the polymer component, but is preferably 40 to 80°C, more preferably 50 to 75°C, even more preferably 55 to 75°C, and also preferably 60 to 72°C.

[0062] The cool-expand conditions in step 3C are the same as in step 2A, and the preferred configuration is also the same. Step 4C is the same as in step 3A, and the preferred configuration is also the same. Furthermore, the process from thermocompression bonding in step 4C to obtaining the semiconductor package can employ a general method as described above.

[0063] The present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the following examples other than those specified in the present invention. Furthermore, although the present invention relates to a dicing die attach film, the description of the preparation of a die attach film characteristic of the present invention will be referred to as "Examples" below for convenience.

[0064] [Example 1] 56 parts by mass of triphenylmethane type epoxy resin (product name: EPPN-501H, weight-average molecular weight: 1000, softening point: 55°C, solid, epoxy equivalent: 167, manufactured by Nippon Kayaku Co., Ltd.), 49 parts by mass of bisphenol A type epoxy resin (product name: YD-128, weight-average molecular weight: 400, softening point: 25°C or lower, liquid, epoxy equivalent: 190, manufactured by Shin-Nippon Chemical Epoxy Manufacturing Co., Ltd.), 30 parts by mass of phenoxy resin (product name: YX7180, weight-average molecular weight: 30000, Tg: 15°C, manufactured by Mitsubishi Chemical Corporation), and 45 parts by mass of methyl ethyl ketone were heated and stirred in a 1000 ml separable flask at 110°C for 2 hours to obtain a resin varnish. Next, transfer this resin varnish to an 800 ml planetary mixer and add alumina filler (product name: AZ2-75, average particle size (d50): 3.0 μm, specific surface area 1.3 m²). ２ / g, perfectly spherical, manufactured by Nippon Steel Chemical & Material Co., Ltd.) 255 parts by mass, alumina filler (product name: AO502, average particle size (d50): 0.2 μm, specific surface area 7.8 m² ２ 64 parts by mass of (spherical, manufactured by Admatex Co., Ltd.), 8.5 parts by mass of imidazole-based curing agent (product name: 2PHZ-PW, manufactured by Shikoku Chemicals Co., Ltd.), and 3.0 parts by mass of silane coupling agent (product name: KBM-403, 3-glycidoxypropyltrimethoxysilane, manufactured by JNC Corporation) were added and stirred and mixed at room temperature for 1 hour. A mixed varnish was then obtained by vacuum degassing. Next, the obtained mixed varnish was applied to a 38 μm thick release-treated PET film and heated and dried (held at 130°C for 10 minutes) to obtain a 10 μm thick die-attach film on the PET film.

[0065] [Example 2] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 1, except that the amount of alumina filler (product name: AZ2-75) was 383 parts by mass and the amount of alumina filler (product name: AO502) was 96 parts by mass.

[0066] [Example 3] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 1, except that the amount of alumina filler (product name: AZ2-75) was 575 parts by mass and the amount of alumina filler (product name: AO502) was 144 parts by mass.

[0067] [Example 4] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 2, except that 30 parts by mass of phenoxy resin (product name: YP-70, weight-average molecular weight: 55,000, Tg: 70°C, manufactured by Nippon Steel Chemical & Material Co., Ltd.) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) as in Example 2.

[0068] [Example 5] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 2, except that 30 parts by mass of urethane resin (product name: UR-3500, weight-average molecular weight: 13000, Tg: 10℃, manufactured by Toyobo MC Co., Ltd.) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) as in Example 2.

[0069] [Example 6] In Example 1, spherical silica (product name: SO-25R, average particle size (d50): 0.5 μm, specific surface area 8 m²) was used instead of alumina filler. ２ A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 1, except that 267 parts by mass of (per gram, perfectly spherical, manufactured by Admatex Co., Ltd.) were used.

[0070] [Example 7] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 6, except that 30 parts by mass of phenoxy resin (product name: YP-70) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) as in Example 6.

[0071] [Example 8] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 6, except that 30 parts by mass of urethane resin (product name: VA-9310MF) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180).

[0072] [Example 9] In Example 1, spheroidal silver (product name: AG-4-8F, average particle size (d50): 2 μm, specific surface area 0.4 m²) was used instead of alumina filler. ２ A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 1, except that 545 parts by mass of (manufactured by DOWA Electronics Co., Ltd.) were used.

[0073] [Example 10] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 9, except that 30 parts by mass of phenoxy resin (product name: YP-70) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) in Example 9.

[0074] [Example 11] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 9, except that 30 parts by mass of urethane resin (product name: VA-9310MF) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180).

[0075] [Comparative Example 1] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 2, except that 30 parts by mass of phenoxy resin (product name: YP-50, weight-average molecular weight: 80000, Tg: 84℃, manufactured by Nippon Steel Chemical & Material Co., Ltd.) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) as in Example 2.

[0076] [Comparative Example 2] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 2, except that 30 parts by mass of acrylic resin (product name: SG-P3, weight-average molecular weight: 800,000, Tg: 12°C, manufactured by Nagase ChemteX Co., Ltd.) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) as in Example 2.

[0077] [Comparative Example 3] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 6, except that 30 parts by mass of phenoxy resin (product name: YP-50) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) as in Example 6.

[0078] [Comparative Example 4] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 6, except that 30 parts by mass of acrylic resin (product name: SG-P3) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) as in Example 6.

[0079] [Comparative Example 5] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 9, except that 30 parts by mass of phenoxy resin (product name: YP-50, weight-average molecular weight: 80000, Tg: 84℃, manufactured by Nippon Steel Chemical & Material Co., Ltd.) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) in Example 9.

[0080] [Comparative Example 6] A die attach film with a thickness of 10 μm was obtained on a PET film in the same manner as in Example 9, except that 30 parts by mass of acrylic resin (product name: SG-P3) were used instead of 30 parts by mass of phenoxy resin (product name: YX7180) as in Example 9.

[0081] [Test Example] <Melting Viscosity> The 10 μm thick die attach film obtained in each example and comparative example was cut to a size of 5.0 cm x 5.0 cm and stacked. On a hot plate at 70°C, it was bonded together with a hand roller to obtain a test specimen with a thickness of approximately 1.0 mm. Using a rheometer (RS6000, Haake), the change in viscous resistance of this test specimen was measured in a temperature range of 20 to 250°C and a heating rate of 5°C / min. The melt viscosity (Pa·s) at 120°C was calculated from the temperature-viscous resistance curve.

[0082] <Coefficient of Linear Expansion> 5 mm square prisms were fabricated from the 10 μm thick die-attach films obtained in each example and comparative example by molding. These molded products were heated at 180°C for 1 hour to cure, and measurement samples were obtained. The measurement samples were set in the measuring jig of a thermomechanical analyzer [TMA7100, manufactured by Hitachi High-Tech Science Co., Ltd.], and the expansion rate was measured in the temperature range of -50°C to 300°C under the conditions of a pressing load of 0.02 N, a probe diameter of 3 mmφ, and a heating rate of 7°C / min. The coefficient of linear expansion (CTEα2) was calculated based on the expansion rate of the cured product in the range of 240 to 260°C (calculated from the expansion rate in the range of 240 to 260°C).

[0083] <Thermal Conductivity> In each example and comparative example, the 10 μm thick die-attach film was cut into square pieces of 50 mm or more on each side. The cut samples were stacked so that the thickness was 5 mm or more, placed on a disc-shaped mold with a diameter of 50 mm and a thickness of 5 mm, and heated for 10 minutes at a temperature of 150°C and a pressure of 2 MPa using a compression press molding machine. The heated samples were then removed and the die-attach film was further heat-cured by heating in a dryer at a temperature of 180°C for 1 hour to obtain a disc-shaped test piece with a diameter of 50 mm and a thickness of 5 mm. The thermal conductivity (W / (m·K)) of this test piece was measured using a thermal conductivity measuring device (product name: HC-110, manufactured by Eiko Seiki Co., Ltd.) by the heat flow meter method (in accordance with JIS-A1412). The measured thermal conductivity is listed in the table below as "bulk thermal conductivity".

[0084] <Die-Sear Adhesion Strength> First, the 10 μm thick die-attach films with PET films obtained in each example and comparative example were bonded to one side of a dummy silicon wafer (8-inch size, 365 μm thick) using a manual laminator (product name: FM-114, manufactured by Technovision Co., Ltd.) at a temperature of 70°C and a pressure of 0.3 MPa. After peeling the PET film from the die-attach film, a dicing film (product name: K-13, manufactured by Furukawa Electric Co., Ltd.) and a dicing frame (product name: DTF2-8-1H001, manufactured by DISCO Corporation) were bonded to the side of the die-attach film opposite to the dummy silicon wafer using the same manual laminator at room temperature and a pressure of 0.3 MPa. Next, using a dicing apparatus (product name: DFD-6340, manufactured by DISCO) equipped with two-axis dicing blades (Z1: NBC-ZH2050 (27HEDD), manufactured by DISCO / Z2: NBC-ZH127F-SE (BC), manufactured by DISCO), dicing was performed on the wafer and die attach film from the wafer side to obtain chips measuring 2 mm vertically x 2 mm horizontally, thereby obtaining semiconductor chips with die attach film pieces attached to the dicing film. Separately, using a manual laminator, the dicing film (product name: K-8, manufactured by Furukawa Electric Co., Ltd.) and the dicing frame (product name: DTF2-8-1H001, manufactured by DISCO) were bonded to one side of a dummy silicon wafer (8-inch size, 365 μm thick) at room temperature and a pressure of 0.3 MPa. Next, using a dicing apparatus equipped with the same two-axis dicing blades as described above, dicing was performed from the wafer side to obtain a chip measuring 12 mm vertically x 12 mm horizontally, thereby obtaining a silicon chip on the dicing film. Then, using a die bonder (product name: DB-800, manufactured by Hitachi High-Technologies Corporation), the semiconductor chip with the die attach film attached was picked up from the dicing film, and the die attach film on one side of the semiconductor chip with the die attach film attached was heat-pressed to bond the mounting side (the uneven side) of the silicon chip. The heat-pressure bonding conditions were 120°C, pressure 0.5 MPa (load 200 gf), and time 1.0 second.In this process, two semiconductor chips with die-attach film pieces attached were positioned spaced apart on the mounting side of the silicon chip. Thus, a sample was obtained in which two semiconductor chips with die-attach film pieces attached were mounted on one silicon chip. Four of these samples were prepared for each example and comparative example. Next, the die-attach film pieces were heat-cured by heating them in a dryer at a temperature of 120°C for 2 hours. After that, the die-shear adhesion strength of the semiconductor chips bonded to the silicon chip surface via the heat-cured die-attach film pieces was measured using a bond tester (product name: 4000 universal bond tester, Daigi Co., Ltd.). The above measurement was performed on eight semiconductor chips (four silicon chips x 2), and the die-shear adhesion strength was evaluated by applying the eight measured values ​​and their average value to the following criteria. - Die-shear adhesion strength evaluation criteria - AA: The average value is 20 MPa or higher, and all eight measured values ​​are 20 MPa or higher. A: The average value is 20 MPa or higher, and 5 to 7 of the 8 measurements are 20 MPa or higher, while the remaining measurements are less than 20 MPa.

[0085] <Package Assembly Ease> The semiconductor package assembly process was simulated by bonding a semiconductor chip with a die-attach film attached to a silicon chip via the die-attach film, and the package assembly ease was evaluated using voids at the interface between the die-attach film and the silicon chip (substrate) as an indicator. Details are described below. The 10 μm thick die-attach film with PET film obtained in each example and comparative example was first bonded to one side of a dummy silicon wafer (8-inch size, 365 μm thick) using the same manual laminator at a temperature of 70°C and a pressure of 0.3 MPa. After peeling the PET film from the die-attach film, a dicing film (product name: K-13, manufactured by Furukawa Electric Co., Ltd.) and a dicing frame (product name: DTF2-8-1H001, manufactured by DISCO Corporation) were bonded to the side of the die-attach film opposite to the dummy silicon wafer using the same manual laminator at room temperature and a pressure of 0.3 MPa. Next, using a dicing apparatus equipped with the same two-axis dicing blades as described above, dicing was performed on the wafer and the die-attach film from the wafer side to obtain a chip measuring 10 mm in length and 10 mm in width, thereby obtaining a semiconductor chip with a die-attach film piece attached on the dicing film. Separately, using a manual laminator, the dicing film (product name: K-8, manufactured by Furukawa Electric Co., Ltd.) and the dicing frame (product name: DTF2-8-1H001, manufactured by DISCO Corporation) were bonded to one side of a dummy silicon wafer (8-inch size, 365 μm thick) at room temperature and a pressure of 0.3 MPa. Next, using a dicing apparatus equipped with the same two-axis dicing blades as described above, dicing was performed from the wafer side to obtain a chip measuring 12 mm in length and 12 mm in width, thereby obtaining a silicon chip on the dicing film. Next, a die bonder (product name: DB-800, manufactured by Hitachi High-Technologies Corporation) was used to pick up the semiconductor chip with the die attach film attached from the dicing film, and the die attach film on one side of the semiconductor chip with the die attach film attached was heat-pressed to bond it to the mounting side of the silicon chip.The conditions for thermocompression bonding were 120°C, 0.5 MPa pressure (200 gf load), and 1.0 second. During this process, a semiconductor chip with a 10 mm x 10 mm die-attach film piece was positioned in the center of the mounting surface of a 12 mm x 12 mm silicon chip. The die-attach film piece was then heat-cured in a dryer at 120°C for 2 hours. For samples with a semiconductor chip bonded to the silicon chip surface via the heat-cured die-attach film piece, the presence or absence of voids at the interface between the die-attach film piece and the silicon chip mounting surface was observed using an ultrasonic flaw detection system (SAT) (FS300III, Hitachi Power Solutions). The above measurements were performed on five samples, and the package assembly feasibility was evaluated according to the following evaluation criteria. —Package Assembly Feasibility Evaluation Criteria— AA: No voids were observed in any of the five samples using a 100 MHz probe. A: Although it does not fall under AA above, no voids were observed in any of the five semiconductor chips using a 50MHz probe.

[0086] <Thermal Conductivity in Package Form> This test evaluates the thermal conductivity of the die-attach film in a laminate (a simulated semiconductor package form, consisting of a semiconductor chip / die-attach film / silicon chip) where the die-attach film is sandwiched between a semiconductor chip and a silicon chip by bonding a semiconductor chip with a die-attach film attached to a silicon chip via the die-attach film. Using the same mixed varnish composition as in each example and comparative example, die-attach films with thicknesses of 10 μm, 20 μm, and 50 μm were obtained on a PET film, respectively. Using the obtained die-attach films, samples of semiconductor chips bonded to the silicon chip surface via a thermo-cured die-attach film were obtained in the same manner as in the package assembly evaluation described above. The thermal resistance of the die-attach film in these samples was measured using a DynTIM Tester (+T3Ster) manufactured by Mentor Graphics under the following conditions. Atmosphere: Air Measurement direction: Thickness direction Measurement temperature: 23°C (low-temperature base temperature) Temperature rise: 5-15°C (temperature difference between the upper and lower surfaces of the sample) The obtained thermal resistance values ​​were plotted against thickness, and the package-type thermal conductivity was calculated as the reciprocal of the slope. In this way, the thermal resistance due to the equipment used for measurement (including semiconductor chips and silicon chips placed above and below the film adhesive) was canceled out, and the thermal conductivity of the die-attach film piece itself was measured. The calculated package-type thermal conductivity was evaluated according to the evaluation criteria below. -Package-type thermal conductivity evaluation criteria- AAA: Package-type thermal conductivity of 2.5 W / m·K or higher AA: Package-type thermal conductivity of 1.5 W / m·K or higher and less than 2.5 W / m·K A: Package-type thermal conductivity of 1.0 W / m·K or higher and less than 1.5 W / m·K B: Package-type thermal conductivity of 0.5 W / m·K or higher and less than 1.0 W / m·K C: Package-type thermal conductivity of less than 0.5 W / m·K

[0087] <Cool Expand Divide> A protective tape was applied to the surface of a silicon wafer (diameter: 12 inches, thickness: 750 μm). Then, a modified region was formed inside the silicon wafer by irradiating it with laser light from the side opposite to the protective tape, under the following stealth dicing conditions. - Stealth Dicing Conditions - Stealth dicing device: DFL7361 (Disco Corporation) Laser oscillator type: Semiconductor laser-pumped Q-switched solid-state laser Wavelength: 1342 nm Frequency: 60 kHz Output: 0.8 W Number of passes: 2 Chip size defined by the modified region: 2 mm (vertical) x 2 mm (horizontal) Dicing speed: 800 mm / sec Next, the side of the silicon wafer opposite to the protective tape was ground using a grinder polisher device (DGP8761, Disco Corporation) until the thickness of the silicon wafer was 50 μm. The die attach films obtained in each example and comparative example were laminated with a dicing film (product name: K-13, manufactured by Furukawa Electric Co., Ltd.) to form a dicing die attach film. This dicing die attach film was then laminated to the side of the silicon wafer opposite the protective tape using a manual laminator at 70°C and a pressure of 0.3 MPa. Next, it was fixed to a dicing frame (product name: DTF2-8-1H001, manufactured by DISCO Corporation), and the protective tape was peeled off from the silicon wafer. Subsequently, using a die separator (DDS2300, manufactured by DISCO Corporation), the dicing film of the dicing die attach film was stretched under the following cool-expand conditions, thereby integrally separating the die attach film and the silicon wafer. After that, the dicing film was heated and shrunk (heat-shrinked) under the following heating conditions. - Cool Expand Conditions - Cooling temperature: -15°C Cooling time: 90 seconds Push-up amount: 10 mm Push-up speed: 300 mm / second Holding time after push-up: 0 seconds - Heating Conditions - Heater temperature: 220°C Heater rotation speed: 10° / second Push-up amount: 11 mm Tape cooling waiting time: 0 seconds After heat shrinking, the separated wafers (semiconductor chips) were visually inspected and evaluated for cool expandability according to the following evaluation criteria.- Cool Expand Disintegration Evaluation Criteria - A: No die fly (chip flying off) occurs, and no edge lifting occurs on the back surface of the semiconductor chip. B: No die fly occurs, but edge lifting occurs on the back surface of the semiconductor chip.

[0088] <Pickup Properties> The die attach films obtained in each example and comparative example were laminated with a dicing film (product name: K-13, manufactured by Furukawa Electric Co., Ltd.) to form a dicing die attach film. This dicing die attach film was then bonded to one side of a dummy silicon wafer (8-inch size, 50 μm thick) using a manual laminator at 70°C and a pressure of 0.3 MPa, and then fixed to a dicing frame (product name: DTF2-8-1H001, manufactured by DISCO). Next, using a dicing apparatus equipped with the same two-axis dicing blades as above, dicing was performed on the wafer and the die attach film from the wafer side to obtain chips with dimensions of 10 mm in length and 10 mm in width, thereby obtaining semiconductor chips with die attach film pieces attached to the dicing film. Next, using a die bonder (product name: DB-800, manufactured by Hitachi High-Technologies Corporation), the semiconductor chips with the die-attach film attached were attempted to be picked up from the dicing film with a pickup time of 100 msec, a push-up speed of 10 mm / sec, a push-up height of 200 μm, and a pickup force of 2 N. The pick-up performance was evaluated based on the following evaluation criteria: - Pick-up Performance Evaluation Criteria - AA: No pickup failures were observed in 100 pickups. A: Pick-up failures were observed in 1 to 10 out of 100 semiconductor chips. B: Pick-up failures were observed in 11 to 50 out of 100 semiconductor chips. C: Pick-up failures were observed in 51 or more out of 100 semiconductor chips. A pickup failure means that the semiconductor chip could not be peeled off the dicing film, part or all of the die-attach film remained on the dicing film after pickup, or the semiconductor chip was damaged by the pickup. All of these phenomena are caused by excessively high peel strength between the die-attach film and the dicing film.

[0089] The results are shown in the table below.

[0090]

[0091]

[0092] As shown in the table above, the die attach films prepared in each example and comparative example were all considered suitable for use as die attach films in terms of melt viscosity, coefficient of linear expansion, bulk thermal conductivity, die shear adhesion, package assembly properties, and package form thermal conductivity. It should be noted that using silica, which has relatively low thermal conductivity, as an inorganic filler also lowers the thermal conductivity of the die attach film. However, these results merely demonstrate that thermal conductivity can be controlled by the type of filler (that the type of filler can be appropriately selected according to the purpose), and are not directly related to solving the problem of the present invention. On the other hand, considering the viewpoint of sufficiently enhancing the adhesion between the die attach film and the semiconductor wafer by bonding them at a relatively mild high temperature range (70°C), and also sufficiently enhancing the integrated separation of the semiconductor wafer and the die attach film at a relatively mild low temperature range (-15°C) during subsequent cool-expanding, the cool-expand separation characteristics and pickup characteristics were evaluated, and the results are as follows. Comparative Examples 1, 3, and 5 use phenoxy resin as the polymer component of the die attach film, but its Tg is higher than 70°C. In this case, even when the dicing die attach film is bonded to the wafer at 70°C, the adhesion between the wafer and the die attach film cannot be sufficiently increased, and during cool expansion, the edges of the bonding surface between the semiconductor chip and the die attach film lift up from the die attach film. In Comparative Examples 2, 4, and 6, the polymer component of the die attach film is acrylic resin with a Tg within the limits of the present invention. In this case, when the dicing die attach film is bonded to the wafer at 70°C, the adhesion between the dicing film and the die attach film becomes excessively high in some areas, making pickup failures likely. In contrast, Examples 1 to 11 use phenoxy resin or polyurethane resin as the polymer component of the die attach film, and their Tg is within the limits of the present invention.In this case, by laminating the dicing die attach film to the wafer at 70°C, the adhesion between the wafer and the die attach film could be sufficiently enhanced. As a result, die fly and edge lifting did not occur during cool expansion at -15°C, and pickup failures were also less likely to occur. In particular, it was found that pickup failures could be reduced more effectively when phenoxy resin was used.

[0093] Although we have described the present invention along with its embodiments, we do not intend to limit our invention in any detail of the description unless specifically designated, and we believe that it should be interpreted broadly without contradicting the spirit and scope of the invention as set forth in the appended claims.

[0094] This application claims priority based on Japanese Patent Application No. 2025-054962, filed in Japan on 28 March 2025, the contents of which are incorporated herein by reference as part of this specification.

Claims

1. A dicing die attach film for use in a cool-expand process, wherein the die attach film of the dicing die attach film contains the following components (a) to (d): (a) epoxy resin; (b) epoxy resin curing agent; (c) phenoxy resin and / or polyurethane resin having a glass transition temperature of -15°C or higher and 70°C or lower; (d) inorganic filler.

2. The dicing die attach film according to claim 1, wherein the content of the inorganic filler (d) in the die attach film is 30 to 65% by volume.

3. The dicing die attach film according to claim 1, wherein the coefficient of linear thermal expansion based on the expansion rate of the cured die attach film in the range of 240 to 260°C is 140 ppm / K or less.

4. The dicing die attach film according to claim 1, wherein when the die attach film is heated from 25°C at a heating rate of 5°C / min, the melt viscosity at 120°C is 10,000 Pa·s or less.

5. The dicing die attach film according to claim 1, wherein the die shear adhesive strength of the cured die attach film is 20 MPa or more.

6. The dicing die attach film according to claim 1, wherein the thermal conductivity of the cured product of the die attach film is 0.4 W / m·K or higher.

7. A method for manufacturing a semiconductor package, comprising the steps of: stealth dicing a semiconductor wafer while the dicing die attach film described in any one of claims 1 to 6 is bonded to the semiconductor wafer; separating the semiconductor wafer integrally with the die attach film by cool expand; and picking up the separated semiconductor chips together with the die attach film pieces and thermocompressing them onto a wiring substrate.

8. A method for manufacturing a semiconductor package, comprising the steps of: stealth dicing a semiconductor wafer; bonding a dicing die-attach film according to any one of claims 1 to 6 to the semiconductor wafer after stealth dicing; integrally separating the semiconductor wafer from the die-attach film by cool-expanding; and picking up the separated semiconductor chips together with the die-attach film pieces and thermocompressing them onto a wiring substrate.

9. A method for manufacturing a semiconductor package, comprising the steps of: forming grooves on the surface of a semiconductor wafer that do not penetrate to the back surface, and then dividing the wafer into individual semiconductor chips by grinding the back surface; laminating a dicing die attach film according to any one of claims 1 to 6 to the back surface; separating the die attach film together with the semiconductor chips by cool expanding; and picking up the semiconductor chips together with the die attach film pieces and thermocompressing them onto a wiring substrate.

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