JP6767698B2 - Acrylic resin composition for encapsulation, semiconductor device and method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a sealing acrylic resin composition, a semiconductor device, and a method for manufacturing a semiconductor device. Specifically, the present invention is suitable for sealing a gap between a base material and a semiconductor chip by a pre-supply method underfilling. Acrylic resin composition for sealing, a semiconductor device sealed by underfilling using this acrylic resin composition for sealing, and a substrate and a semiconductor chip by underfilling in a pre-supply method using this acrylic resin composition for sealing. The present invention relates to a method for manufacturing a semiconductor device that seals a gap between the two.

When a flip-chip type semiconductor chip 3 is mounted face-down on a base material, for example, FC-BGA (flip chip-ball grid array) has been conventionally used as the semiconductor chip 3. The distance between the bump electrodes 33 in FC-BGA is 150 μm or more (see FIG. 3B). An underfilling technique in which a semiconductor chip 3 is mounted on a base material and then the gap between the base material and the semiconductor chip 3 is filled with a resin composition to seal the gap is also widely adopted.

In recent years, in order to increase the integration of electronic components, it has been required to narrow the pitch between bump electrodes 33 in the semiconductor chip 3. Therefore, as the semiconductor chip 3, FC-CSP (flip chip-chip size package) as shown in FIG. 3A has been proposed. The bump electrode 33 in the semiconductor chip 3 shown in FIG. 3A is composed of a copper pillar 31 and a solder bump 32 provided at the tip thereof. This makes it possible to reduce the pitch between the bump electrodes 33 to 100 μm or less. Further, when the pillar 31 is made of copper, it is possible to increase the amount of energization in the bump electrode 33 and improve the thermal conductivity of the bump electrode 33. Further, since the bump electrode 33 includes the pillar 31, the amount of solder in the bump electrode 33 can be suppressed. Further, since the pillar 31 does not melt during the reflow process, a short circuit due to the spread of the solder can be suppressed.

With the narrowing of the pitch of the bump electrode, the pre-supply method is attracting attention as an underfilling technique. In this pre-supply method, for example, a base material provided with conductor wiring, a semiconductor chip provided with bump electrodes, and a thermosetting acrylic resin composition liquid at room temperature are prepared. The sealing acrylic resin composition is arranged on the base material, the semiconductor chip is arranged at the position where the sealing acrylic resin composition is arranged on the base material, and the bump electrode is arranged on the conductor wiring. In this state, by heating the sealing acrylic resin composition and the bump electrode, the sealing acrylic resin composition is cured to form a sealing material, and the bump electrode and the conductor wiring are electrically connected. .. As a result, the mounting of the semiconductor chip on the base material and the sealing of the gap between the semiconductor chip and the base material can be performed at the same time. Moreover, even if the pitch between the bump electrodes is narrow, the gap between the semiconductor chip and the base material is unlikely to be unfilled with the sealing material.

When sealing by the pre-supply method, an activator (flux) containing an organic acid or the like is added to the sealing acrylic resin composition in order to remove the oxide film on the solder bumps and ensure the connection reliability with the conductor wiring. It is contained (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-243786

However, when the semiconductor chip provided with the bump electrode and the base material are sealed with an acrylic resin composition containing an organic acid, the organic acid in the sealing material formed from the acrylic resin composition moves. This may cause a short circuit between the bump electrodes. In particular, when the pitch between the bump electrodes becomes narrow as in recent years, the potential gradient between the bump electrodes becomes large and the organic acid easily moves, so that the risk of short circuit increases.

The present invention has been made in view of the above reasons, and when the gap between the semiconductor chip and the base material is sealed with the sealing acrylic resin composition containing an organic acid, the sealing acrylic resin composition is used. Acrylic resin composition for sealing capable of suppressing short circuit due to movement of organic acid in a sealing material formed from an object, a semiconductor device sealed using this acrylic resin composition for sealing, and the present invention. An object of the present invention is to provide a method for manufacturing a semiconductor device using an acrylic resin composition for encapsulation.

The sealing acrylic resin composition according to the present invention contains a compound having a (meth) acryloyl group, a thermal radical polymerization initiator, an organic acid, and a compound having a function of capturing an organic acid.

The semiconductor device according to the present invention includes a base material, a semiconductor chip mounted face-down on the base material, and a sealing material for sealing a gap between the base material and the semiconductor chip. The sealing material comprises a cured product of the sealing acrylic resin composition.

In the method for manufacturing a semiconductor device according to the present invention, a base material provided with conductor wiring and a semiconductor chip provided with a bump electrode are prepared, the sealing acrylic resin composition is arranged on the base material, and the base material is provided. The semiconductor chip is arranged at a position where the sealing acrylic resin composition is arranged, and the bump electrode is arranged on the conductor wiring, so that the sealing acrylic resin composition and the bump electrode are placed. By heating, the sealing acrylic resin composition is cured to form a sealing material, and the bump electrode and the conductor wiring are electrically connected.

According to the present invention, when the gap between the semiconductor chip and the base material is sealed with the sealing acrylic resin composition containing an organic acid, the sealing material formed from the sealing acrylic resin composition. It is possible to suppress a short circuit due to the movement of the organic acid inside.

Each of FIGS. 1A to 1D is a schematic cross-sectional view showing a process of manufacturing a semiconductor device according to an embodiment of the present invention. 2A to 2C are conceptual diagrams showing the mechanism of suppressing the movement of organic acids in the encapsulant estimated in the present embodiment. Each of FIGS. 3A and 3B is a perspective view showing an example of a semiconductor chip.

The sealing acrylic resin composition according to this embodiment will be described.

The sealing acrylic resin composition according to the present embodiment is particularly suitable for sealing the gap between the base material 2 and the semiconductor chip 3 by the pre-supply method underfilling (see FIGS. 1A to 1D). ).

The sealing acrylic resin composition according to the present embodiment is preferably liquid at room temperature. The sealing acrylic resin composition according to the present embodiment does not have to be liquid at room temperature. "Liquid at room temperature" means having fluidity at 18 ° C. under atmospheric pressure. In particular, the acrylic resin composition for sealing preferably has fluidity under atmospheric pressure at any temperature in the range of 5 to 28 ° C.

The sealing acrylic resin composition contains an acrylic resin, a thermal radical polymerization initiator, an organic acid, and a compound having a function of capturing an organic acid (hereinafter, referred to as an organic acid scavenger). The sealing acrylic resin composition preferably further contains an inorganic filler.

The acrylic resin has thermosetting property and is preferably liquid at room temperature. In particular, the acrylic resin set preferably has fluidity under atmospheric pressure at any temperature within the range of 5 to 28 ° C. When the sealing acrylic resin composition contains an acrylic resin, voids are less likely to occur in the sealing material 42 formed from the sealing acrylic resin composition. It is considered that this is because the sealing acrylic resin composition thickens in the initial stage when the acrylic resin is cured by the radical polymerization reaction.

In order to ensure the heat resistance of the encapsulant 42, the acrylic resin preferably contains a compound having two or more (meth) acryloyl groups per molecule, and 2 to 6 (meth) per molecule. It is more preferable to contain a compound having an acryloyl group, and further preferably to contain a compound having two (meth) acryloyl groups per molecule.

Examples of the compound having two (meth) acryloyl groups per molecule include ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate. , 1,9-Nonandiol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dimerdiol di (meth) acrylate, dimethylol tricyclodecandi (meth) ) Acrylate, Diethylene glycol di (meth) acrylate, Triethylene glycol di (meth) acrylate, Tetraethylene glycol di (meth) acrylate, Polyethylene glycol di (meth) acrylate, Tripropylene glycol di (meth) acrylate, Polypropylene glycol di (meth) ) Acrylate, glycerin di (meth) acrylate, trimethyl propandi (meth) acrylate, pentaerythritol di (meth) acrylate, zinc di (meth) acrylate, cyclohexanediol di (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, Included are cyclohexanediethanol di (meth) acrylates, cyclohexanedialkyl alcohol di (meth) acrylates, and dimethanol tricyclodecanedi (meth) acrylates.

As a compound having two (meth) acryloyl groups per molecule, 1 mol of bisphenol A, bisphenol F or bisphenol AD and 2 mol of glycidyl acrylate, 1 mol of bisphenol A, bisphenol F or bisphenol AD and 2 mol of glycidyl methacrylate The reactants of

Examples of the compound having two or more (meth) acryloyl groups per molecule include (meth) acrylate having a crosslinked polycyclic structure. Specifically, examples of the compound having two or more (meth) acryloyl groups per molecule include a compound represented by the following formula (I) and a compound represented by the following formula (II). In this case, the heat resistance of the sealing material 42 is particularly improved.

In formula (I), each of R ¹ and R ² represents a hydrogen atom or a methyl group, where a is 1 or 2 and b is 0 or 1.

In formula (II), each of R ³ and R ⁴ represents a hydrogen atom or a methyl group, X represents a hydrogen atom, a methyl group, a methylol group, an amino group, or a (meth) acryloyloxymethyl group, and c is 0. Or 1.

More specific examples of the (meth) acrylate having a crosslinked polycyclic structure include, for example, a (meth) acrylate having a dicyclopentadiene skeleton in which a is 1 and b is 0 in the formula (I), the formula (II). A (meth) acrylate having a perhydro-1,4: 5,8-dimethanonaphthalene skeleton in which c is 1, a (meth) acrylate having a norbornane skeleton in which c is 0 in formula (II), formula (I). R ¹ and R ² are hydrogen atoms in), a = 1, b = 0 and a dicyclopentadienyl diacrylate (tricyclodecane diacrylate), X in formula (II) acryloyloxy methyl radical, R Perhydro-1,4: 5,8-dimethanonaphthalene-2,3,7-trimethylol triacrylate in which ³ and R ⁴ are hydrogen atoms and c is 1, X, R ³ and R ⁴ in formula (II). Is a hydrogen atom, c is 0, norbornane dimethylol diacrylate, and X, R ³ and R ⁴ in formula (II) are hydrogen atoms, c is 1 perhydro-1,4: 5,8-dimethanonaphthalene. −2,3-Dimethylol diacrylate can be mentioned. In particular, the (meth) acrylate having a crosslinked polycyclic structure preferably contains at least one of dicyclopentadienyl diacrylate and norbornane dimethylol diacrylate.

Examples of the compound having two or more (meth) acryloyl groups include di (meth) acrylate having a structure in which an alkylene oxide is added to a bisphenol skeleton. Specifically, examples of the compound having two or more (meth) acryloyl groups include a compound represented by the formula (III) and a compound represented by the formula (IV). In this case, the adhesion between the sealing material 42 and the semiconductor chip 3 and the base material 2 is improved.

In formula (III), R ⁵ represents a hydrogen, methyl group, or ethyl group, R ⁶ represents a divalent organic group, and each of m and n represents an integer of 1 to 20.

In formula (IV), R ⁵ represents a hydrogen, methyl group, or ethyl group, R ⁶ represents a divalent organic group, and each of m and n represents an integer of 1 to 20.

More specific examples of di (meth) acrylate having a structure in which an alkylene oxide is added to a bisphenol skeleton include Aronix M-210, M-221B (manufactured by Toa Synthetic), NK ester ABE-300, and A-BPE. -4, A-BPE-6, A-BPE-10, A-BPE-20, A-BPE-30, BPE-100, BPE-200, BPE-500, BPE-900, BPE-1300N (New Nakamura Chemical) EO-modified bisphenol A-type di (meth) acrylate (n = 2-20); EO-modified bisphenol F-type di (meth) acrylate (n = 2-20) such as Aronix M-208 (manufactured by Toa Synthetic) PO-modified bisphenol A type di (meth) acrylate (n = 2-20) such as Denacol acrylate DA-250 (manufactured by Nagase Kasei), Viscoat 540 (manufactured by Osaka Organic Chemical Industry); and Denacol acrylate DA-721 (manufactured by Osaka Organic Chemical Industry). (Nagase Kasei) and other PO-modified phthalic acid diacrylates can be mentioned.

Epoxy (meth) acrylate is preferable as the compound having two or more (meth) acryloyl groups. In this case, especially when the sealing acrylic resin composition contains an epoxy resin, the reactivity of the sealing acrylic resin composition is improved, and the heat resistance and adhesion of the sealing material 42 are improved.

Epoxy (meth) acrylate is an oligomer which is an addition reaction product of, for example, an epoxy resin and an unsaturated monobasic acid such as acrylic acid and methacrylic acid.

The epoxy resin which is a raw material of epoxy (meth) acrylate includes, for example, a diglycidyl compound (bisphenol type epoxy resin) obtained by condensing bisphenols typified by bisphenols such as bisphenol A and bisphenol F with epihalohydrin. The epoxy resin may include an epoxy resin having a phenol skeleton. As the epoxy resin having a phenol skeleton, a polyvalent glycidyl ether (phenol novolac type epoxy resin, cresol novolac type) obtained by condensing phenol novolacs, which is a condensate of phenol or cresol and an aldehyde typified by formalin, with epihalohydrin. Epoxy resin). The epoxy resin may include an epoxy resin having a cyclohexyl ring.

The epoxy (meth) acrylate preferably contains, for example, a bisphenol A type epoxy acrylate which is a solid at 25 ° C. or a liquid having a viscosity of 10 Pa · s or more. The bisphenol A type epoxy acrylate is represented by, for example, the following formula (V).

In equation (V), n represents a positive integer.

Commercially available products of bisphenol A type epoxy acrylate include Denacol acrylate DA-250 (Nagase Kasei, 60 Pa · s at 25 ° C), Denacol acrylate DA-721 (Nagase Kasei, 100 Pa · s at 25 ° C), Lipoxy VR- Examples thereof include 60 (Showa High Polymer, solid at room temperature) and Lipoxy VR-77 (Showa High Polymer, 100 Pa · s at 25 ° C.).

When the acrylic resin contains a compound having three or more (meth) acryloyl groups, examples of the compound having three or more (meth) acryloyl groups include pentaerythritol triacrylate, pentaerythritol tetraacrylate, and pentaerythritol pentaacrylate. , Ethoxylated (3) trimethylol propanetriacrylate, ethoxylated (6) trimethylol propanetriacrylate, ethoxylated (9) trimethylol propanetriacrylate, propoxydated (6) trimethylol propanetriacrylate, propoxylated (3) Glyceryl triacrylate, hyperpropoxylated (55) glyceryl triacrylate, ethoxylated (15) trimethyl propanetriacrylate, trimethyl propanetrimethacrylate, tetraethylene glycol diacrylate, dimethylol propanetetraacrylate, tripropylene glycol diacrylate, penta Examples thereof include acrylate ester, 1,3-adamantan diol dimethacrylate, 1,3-adamantan diol diacrylate, 1,3-adamantan dimethanol dimethacrylate, and 1,3-adamantan dimethanol diacrylate.

Acrylic resins include, for example, (meth) acrylate having a crosslinked polycyclic structure of 10 to 50% by mass, di (meth) acrylate having a structure in which an alkylene oxide is added to a bisphenol skeleton of 3 to 20% by mass, and 5 to 30. It can contain mass% epoxy (meth) acrylate.

The acrylic resin may contain various vinyl monomers other than the above-mentioned components, for example, monofunctional vinyl monomers.

The sealing acrylic resin composition may further contain a thermosetting resin other than the acrylic resin. Examples of such a thermosetting resin include a resin that causes a thermosetting reaction with an acrylic resin. Specific examples of such thermosetting resins include bismaleimide resins.

The sealing acrylic resin composition may contain an elastomer. Examples of the elastomer include maleic anhydride adducts of isoprene polymers.

The thermal radical polymerization initiator contains, for example, an organic peroxide. The 1-minute half-life temperature of the organic peroxide is preferably in the range of 120 to 195 ° C, more preferably in the range of 150 to 190 ° C. In this case, the sealing acrylic resin composition thickens quickly to the extent that the wettability between the bump electrode 33 and the conductor wiring 21 is not impaired at the initial stage in the step of heat-curing the sealing acrylic resin composition. , Void formation is suppressed. Further, when the curing reaction proceeds sufficiently fast, peeling between the semiconductor chip 3 and the sealing material 42 can be suppressed.

Specific examples of the organic peroxide include t-butylperoxy-2-ethylhexyl monocarbonate (1 minute half-life temperature 161.4 ° C.), t-butylperoxybenzoate (1 minute half-life temperature 166.8 ° C.), and the like. t-butylcumyl peroxide (1 minute half-life temperature 173.3 ° C), dicumyl peroxide (1 minute half-life temperature 175.2 ° C), α, α'-di (t-butylperoxy) diisopropylbenzene (1 minute half-life temperature 175.2 ° C.) 1 minute half-life temperature 175.4 ° C.), 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (1 minute half-life temperature 179.8 ° C.), di-t-butyl peroxide (1 minute half-life temperature 179.8 ° C.) 1 minute half-life temperature 185.9 ° C.) and 2,5-dimethyl-2,5-bis (t-butylperoxy) hexin (1 minute half-life temperature 194.3 ° C.).

The amount of the organic peroxide is preferably in the range of 0.2 to 2 parts by mass with respect to 100 parts by mass of the acrylic resin. In this case, the viscosity stability of the sealing acrylic resin composition is good, and the decrease in adhesion can be suppressed.

The organic acid is contained as an activator in the sealing acrylic resin composition. In this case, the oxide film on the surface of the bump electrode is removed by the action of the organic acid during reflow, and good connection reliability between the semiconductor chip 3 and the base material 2 is ensured.

Organic acids include, for example, avietic acid, glutaric acid, succinic acid, malonic acid, oxalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, diglycolic acid, thiodiglycolic acid, phthalic acid, isophthalic acid, terephthalic acid. , Propantricarboxylic acid, citric acid, benzoic acid and tartaric acid can contain one or more compounds selected from the group. In particular, in order to particularly improve the wettability between the bump electrode 33 and the conductor wiring 21, the organic acid may contain one or more compounds selected from the group consisting of abietic acid, glutaric acid, oxalic acid and benzoic acid. preferable.

The organic acid is preferably in the range of 0.1 to 20% by mass, more preferably in the range of 0.1 to 10% by mass with respect to the entire sealing acrylic resin composition. In this case, the organic acid particularly exerts the flux activity, and the wettability between the bump electrode and the conductor wiring 21 becomes particularly high. Further, it is possible to suppress the organic acid from making the sealing material 42 brittle and impairing the insulation reliability of the sealing material 42, and it is also possible to suppress the bleeding of the organic acid from the sealing material 42. ..

The organic acid scavenger preferably has a function of capturing at least one of an ionized organic acid and a charged organic acid. In this case, the short circuit due to the movement of the ionized organic acid or the charged organic acid in the sealing material 42 is effectively suppressed.

The organic acid scavenger can contain, for example, an ion scavenger. In this case, the organic acid scavenger can effectively capture the ionized organic acid or the charged organic acid, whereby the short circuit due to the movement of the organic acid in the encapsulant 42 is more effectively suppressed. To. The ion scavenger is also called an ion catcher and consists of, for example, an ion exchanger. More specifically, the organic acid scavengers include Zr-based ion scavengers (for example, IXE-100 and IXE-800 manufactured by Toa Synthetic Co., Ltd.) and Sb-based ion scavengers (for example, IXE-300 manufactured by Toa Synthetic Co., Ltd.). ), Bi-based scavenger (for example, IXE-500 manufactured by Toa Synthetic Co., Ltd.), Mg-Al-based scavenger (for example, IXE-700F and IXE-770D manufactured by Toa Synthetic Co., Ltd.), Sb-Bi-based scavenger Agent (for example, IXE-600 manufactured by Toa Synthetic Co., Ltd.), Zr-Bi scavenger (for example, IXE-6107 and IXE PLAS-B1 manufactured by Toa Synthetic Co., Ltd.), Zr-Mg-Al scavenger (for example) IXE PLAS-A1 and IXE PLAS-A2) manufactured by Toa Synthetic Co., Ltd., bismuth oxide scavenger, antimony oxide scavenger, titanium phosphate scavenger, zirconium phosphate scavenger and hydrotalcite It can contain one or more components selected from the group consisting of system ion scavengers. In particular, the organic acid scavengers are Mg-Al ion scavenger, Zr-Bi ion scavenger, Zr-Mg-Al ion scavenger, Bi ion scavenger, Mg-Al ion scavenger and Zr ion. It preferably contains one or more components selected from the group consisting of scavengers. In this case, the short circuit due to the movement of the organic acid in the sealing material 42 is more effectively suppressed.

The organic acid scavenger is preferably in the range of 0.01 to 15% by mass with respect to the entire sealing acrylic resin composition. When the organic acid scavenger is 0.01% by mass or more, the short circuit due to the movement of the organic acid in the encapsulant 42 is more effectively suppressed. When the organic acid scavenger is 15% by mass or less, the organic acid is suppressed from being excessively trapped by the organic acid scavenger in the sealing acrylic resin composition, and the flux action by the organic acid is stable. Secured. It is more preferable that the organic acid scavenger is in the range of 0.5 to 2.0% by mass.

The sealing acrylic resin composition preferably contains an inorganic filler. In this case, the coefficient of thermal expansion of the sealing material 42 can be adjusted. In addition, the inorganic filler can improve the thermal conductivity of the sealing material 42, whereby the heat generated from the semiconductor chip 3 can be efficiently dissipated through the sealing material 42.

Inorganic fillers include, for example, silica powders such as molten silica, synthetic silica, crystalline silica; oxides such as alumina and titanium oxide; silicates such as talc, calcined clay, unfired clay, mica and glass; calcium carbonate, carbonates. Carbonates such as magnesium and hydrotalcite; hydroxides such as aluminum hydroxide, magnesium hydroxide and calcium hydroxide; sulfates or sulfites such as barium sulfate, calcium sulfate and calcium sulfite; zinc borate, barium metaborate , Borates such as aluminum borate, calcium borate, sodium borate; and one or more materials selected from the group consisting of nitrides such as aluminum nitride, boron nitride, silicon nitride and the like. The molten silica may be either fused spherical silica or fused crushed silica. In particular, it is preferable that the inorganic filler contains at least one of silica and alumina.

The shape of the inorganic filler is not particularly limited, such as crushed, needle-shaped, scaly, and spherical, but the dispersibility of the inorganic filler in the sealing acrylic resin composition is improved, and the viscosity of the sealing acrylic resin composition is controlled. For this purpose, the inorganic filler is preferably spherical.

The inorganic filler preferably has an average particle size smaller than the dimension between the base material 2 and the semiconductor chip 3 mounted therein.

Further, in order to improve the filling density of the inorganic filler in the sealing acrylic resin composition and the sealing material 42 and to adjust the viscosity of the sealing acrylic resin composition, the average particle size of the inorganic filler is 10 μm or less. It is preferably 5 μm or less, more preferably 3 μm or less, and particularly preferably within the range of 0.5 to 2 μm.

The average particle size in this embodiment is a median diameter calculated from the result of particle size distribution measurement by the laser light diffraction method.

In order to adjust the viscosity of the sealing acrylic resin composition or the physical properties of the sealing material 42, the inorganic fillers may contain two or more kinds of components having different average particle sizes.

The amount of the inorganic filler is, for example, in the range of 25 to 70% by mass with respect to the entire sealing acrylic resin composition. In order to improve the heat dissipation of the semiconductor chip 3 by the sealing material 42, the amount of the inorganic filler is preferably in the range of 60 to 80% by mass with respect to the entire sealing acrylic resin composition.

The acrylic resin composition for encapsulation may contain additives other than the above components as long as the effects of the present invention are not impaired. Additives include, for example, silane coupling agents, antifoaming agents, leveling agents, low stress agents, and pigments. However, it is preferable that the acrylic resin composition for sealing does not contain a solvent.

The sealing acrylic resin composition is prepared, for example, by the following method.

First, a mixture is obtained by blending components other than the inorganic filler of the sealing acrylic resin composition at the same time or separately. This mixture is stirred and mixed while performing heat treatment and cooling treatment as necessary. Inorganic filler is then added to this mixture. Next, this mixture is stirred and mixed again while performing heat treatment and cooling treatment as necessary. Thereby, the acrylic resin composition for sealing can be obtained. For stirring the mixture, for example, a dispenser, a planetary mixer, a ball mill, a three-roll or the like can be used in combination.

The sealing acrylic resin composition is suitable as an underfill. 1A to 1D show an example of a method of obtaining a semiconductor device 1 by sealing a gap between a base material 2 and a semiconductor chip 3 by a pre-supply method underfilling using an acrylic resin composition for sealing. Will be described with reference to.

The base material 2 is, for example, a mother substrate, a package substrate, or an interposer substrate. For example, the base material 2 includes an insulating substrate made of glass epoxy, polyimide, polyester, ceramic, or the like, and a conductor wiring 21 made of a conductor such as copper formed on the surface of the insulating substrate. The conductor wiring 21 includes, for example, an electrode pad 22.

The semiconductor chip 3 is a flip chip type chip such as a BGA (ball grid array), an LGA (land grid array), or a CSP (chip size package). Further, the semiconductor chip 3 may be a PoP (package on package) type chip.

The semiconductor chip 3 includes a plurality of bump electrodes 33. The bump electrode 33 includes, for example, as shown in FIG. 3A, a pillar 31 and a solder bump 32 provided at the tip of the pillar 31. In this case, it is easy to narrow the pitch between the adjacent bump electrodes 33. The pillar 31 is made of copper, for example. The copper pillar 31 is also called a copper pillar. The height of the pillar 31 is, for example, in the range of 15 to 50 μm. The solder bumps 32 are, for example, Sn-3.5Ag (melting point 221 ° C.), Sn-2.5Ag-0.5Cu-1Bi (melting point 214 ° C.), Sn-0.7Cu (melting point 227 ° C.), Sn-3Ag-0. It is made of lead-free solder having a melting point of 210 ° C. or higher, such as .5 Cu (melting point 217 ° C.).

In the present embodiment, the pitch between adjacent bump electrodes 33 is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less. In this case, it is possible to cope with high integration of electronic components. Further, the pitch between the adjacent bump electrodes 33 is, for example, 30 μm or more, but is not limited to this.

In this embodiment, the semiconductor chip 3 may include a bump electrode 33 made of a solder ball as shown in FIG. 3B.

In this method, the semiconductor chip 3 can be mounted face-down on the base material 2 by using the flip chip bonder 50 including the bonding head 51 and the stage 52.

In this method, first, as shown in FIG. 1A, the sealing acrylic resin composition is arranged as the underfill 41 on the surface of the base material 2 provided with the conductor wiring 21. Examples of the method for arranging the acrylic resin composition for sealing include a method using a dispenser, a screen printing method, and an inkjet method.

Next, the base material 2 is supported by the stage 52, and the semiconductor chip 3 is held by the bonding head 51. In this state, the bonding head 51 is moved toward the stage 52 as shown in FIG. 1B. As a result, the semiconductor chip 3 is arranged at the position on the base material 2 where the sealing acrylic resin composition is arranged. At this time, the semiconductor chip 3 is arranged in a state where the semiconductor chip 3 and the base material 2 are aligned so that the bump electrode 33 in the semiconductor chip 3 and the electrode pad 22 in the conductor wiring 21 of the base material 2 overlap.

In this state, the bump electrode 33 and the sealing acrylic resin composition are heated by heating the semiconductor chip 3 and the base material 2 through the bonding head 51 and the stage 52. Then, the solder bumps 32 are melted, so that the bump electrodes 33 and the electrode pads 22 are electrically connected. Further, the sealing acrylic resin composition is heat-cured to form a sealing material 42 as shown in FIG. 1C, whereby the semiconductor chip 3 and the base material 2 are sealed with the sealing material 42. Will be done. Subsequently, as shown in FIG. 1D, the bonding head 51 is moved upward and separated from the semiconductor chip 3. As described above, the semiconductor chip 3 is mounted on the base material 2, the semiconductor chip 3 is mounted face-down on the base material 2, and the gap between the base material 2 and the semiconductor chip 3 is formed. A semiconductor device 1 including a sealing material 42 for sealing is obtained.

The heating temperature of the bump electrode 33 and the sealing acrylic resin composition is appropriately set according to the composition of the solder bump 32 and the composition of the sealing acrylic resin composition. For example, the maximum heating temperature is 180 to 300 ° C. It is within the range.

When the semiconductor chip 3 is mounted on the base material 2 and the space between the base material 2 and the semiconductor chip 3 is sealed in this way, the organic acid is contained in the sealing acrylic resin composition. The oxide film on the solder bump 32 is removed by the action of the organic acid, whereby the connection reliability between the semiconductor chip 3 and the base material 2 is ensured.

Excess organic acid that was not consumed for removing the oxide film remains in the sealing material 42. However, since the encapsulant 42 contains an organic acid scavenger, the movement of the organic acid is suppressed even if a potential gradient is generated in the encapsulant 42. Therefore, the short circuit caused by the movement of the organic acid is suppressed.

The mechanism of suppressing the movement of organic acids estimated in the present embodiment is shown in FIGS. 2A to 2C. FIG. 2A shows a state in which the space between the adjacent bump electrodes 33 is filled with the sealing material 42, and the organic acid 220 and the organic acid scavenger 190 are dispersed in the sealing material 42. When a potential gradient is generated between the adjacent bump electrodes 33, the organic acid 200 moves as shown by the arrow in FIG. 2B. At this time, for example, the organic acid 200 that has a negative charge due to being ionized or charged moves. If the organic acid 200 continues to move as it is, a short circuit will occur between the adjacent bump electrodes 33. However, in the present embodiment, as shown in FIG. 2C, the organic acid trapping agent 190 in the encapsulant 42 traps the organic acid 200, thereby inhibiting the movement of the organic acid 200, thereby suppressing a short circuit. It is estimated to be.

In the present embodiment, the organic acid scavenger is preferably solid at 300 ° C. or lower. It is also preferable that the organic acid scavenger does not dissolve in the sealing acrylic resin composition. When the organic acid scavenger is liquid at less than 300 ° C., or volatilizes or gasifies at less than 300 ° C., the organic acid scavenger may be easily affected by heat such as reflow treatment. If the organic acid scavenger does not dissolve in the sealing acrylic resin composition, the position of the organic acid scavenger is fixed in the sealing material 42 to capture the organic acid by the organic acid scavenger. The function can be maintained for a long period of time. Further, if the organic acid scavenger is not dissolved, the organic acid scavenger after capturing the organic acid does not easily move in the encapsulant 42, so that excellent reliability is exhibited.

When the number of bump electrodes 33 in one semiconductor chip 3 is as large as several thousand, the semiconductor chip 3 is mounted on the base material 2 and then the base material 2 and the semiconductor chip 3 are combined with a sealing composition. Sealing the gaps between them may cause problems due to flux cleanability and fillability. This is a case where it is difficult to completely remove the flux component remaining around the thousands of bump electrodes 33 and then evenly fill the sealing composition between the base material 2 and the semiconductor chip 3. Because there is.

On the other hand, when the semiconductor chip 3 is mounted on the base material 2 and the gap between the base material 2 and the semiconductor chip 3 is sealed by using the sealing acrylic resin composition according to the present embodiment, bumps in the semiconductor chip 3 are formed. Even when the number of electrodes 33 is as large as several thousand, the stress generated in the bump electrodes 33 can be relaxed.

When the sealing composition contains an epoxy resin, the halogen component tends to remain in the epoxy resin during the production of the epoxy resin, and therefore, there is a problem that the halogen component is mixed in the sealing composition. become. However, in the embodiment of the present application, since the sealing acrylic resin composition contains an acrylic resin in which no halogen component remains at the time of production, it is difficult for the halogen component to be mixed in the sealing acrylic resin composition. Therefore, it is suppressed that the halogen component in the sealing material 42 inhibits the function of the organic acid scavenger to capture the organic acid. The sealing acrylic resin composition preferably does not contain a halogen component other than the residual halogen component in the resin. In order to maintain the function of the organic acid scavenger in the encapsulant 42 well, the content of halogen atoms in the entire encapsulating acrylic resin composition is preferably 50 mass ppm or less, preferably 10 mass ppm or less. If it is, it is more preferable.

In the present embodiment, the sealing acrylic resin composition contains an organic acid scavenger such as an ion scavenger, but the ion scavenger has conventionally been used to capture halogen ions in a solder resist or the like containing an epoxy resin. It is used. Halogen ions are inevitably mixed with the epoxy resin in the manufacturing process. On the other hand, since the sealing acrylic resin composition according to the present embodiment contains a thermosetting acrylic resin instead of an epoxy resin as the thermosetting resin, it is not necessary to capture halogen ions derived from the epoxy resin. However, in the present embodiment, a new problem of suppressing a short circuit due to the movement of the organic acid in the sealing material formed from the sealing acrylic resin composition containing the organic acid caused by the organic acid is solved. Therefore, the acrylic resin composition for sealing contains an organic acid scavenger such as an ion scavenger. Such an idea cannot be easily obtained from the conventionally known ion scavengers.

Further, in the present embodiment, as described above, the organic acid ionized or negatively charged in the encapsulant 42 is captured by the organic acid scavenger when moving in the presence of the potential gradient. The action of capturing an organic acid by such an organic acid scavenger is difficult to work in the sealing acrylic resin composition before curing. Therefore, the organic acid scavenger does not easily impair the storage stability of the sealing acrylic resin composition.

[Preparation of composition]
For each Example and Comparative Example, the components shown in Tables 1 to 3 are dissolved and mixed by stirring with a homodisper, and further kneaded with a planetary mixer and three rolls to form a liquid. An acrylic resin composition for sealing was obtained. In Examples 17 and 22, kneading using three rolls was performed twice, and in other cases, kneading was performed once.
-Acrylic resin 1: Bisphenol F type epoxy acrylate, manufactured by KSM, product number BFEA-50.
-Acrylic resin 2: Tricyclodecanedimethanol diacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., product number A-DCP.
-Acrylic resin 3: Bisphenol A type epoxy acrylate, manufactured by Showa High Polymer Co., Ltd., product number VR-77.
-Acrylic resin 4: Ethoxylated bisphenol A diacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., product number ABE300.
-Bismaleimide resin: BMI1500.
-Elastomer: Maleic anhydride adduct of isoprene polymer, manufactured by Kuraray Co., Ltd., product number LIR403.
-Organic peroxide: manufactured by NOF Corporation, product name Perbutyl Z.
-Synthetic silica: Made by Fuso Chemical Co., Ltd., product number SP4B.
-Fused silica: manufactured by Tokuyama Corporation, product number SS10, average particle size 1.0 μm.
-Alumina: manufactured by Admatex Co., Ltd., product number AO-502, average particle size 0.6 μm.
-Organic acid 1: Benzoic acid.
-Organic acid 2: Oxalic acid.
-Organic acid 3: Glutaric acid.
-Organic acid 4: Abietic acid.
-Organic acid scavenger A: Zr-Bi-based ion scavenger, both ion exchange type, median diameter 1.5 μm, manufactured by Toagosei Co., Ltd., product number IXE-6107.
-Organic acid scavenger B: Mg-Al ion scavenger, median diameter 6.0 μm, manufactured by Toagosei Co., Ltd., product number IXE-770D.
-Organic acid scavenger C: Zr-Bi scavenger, median diameter 0.4 μm, manufactured by Toagosei Co., Ltd., product number IXE PLAS-B1.
-Organic acid scavenger D: Zr-Mg-Al ion scavenger, median diameter 0.2 μm, manufactured by Toagosei Co., Ltd., product number IXE PLAS A2.
-Organic acid scavenger E: Bi-based ion scavenger, median diameter 1.5 μm, manufactured by Toagosei Co., Ltd., product number IXE-500.
-Organic acid scavenger F: Mg-Al ion scavenger, median diameter 1.5 μm, manufactured by Toagosei Co., Ltd., product number IXE-700F.
-Organic acid scavenger G: Zr-based ion scavenger, median diameter 2.0 μm, manufactured by Toagosei Co., Ltd., product number IXE-800.

[Evaluation test]
The following evaluation tests were carried out on the sealing acrylic resin compositions obtained in each Example and Comparative Example. The results of these evaluation tests are shown in Tables 1 to 3.

(1) Void evaluation A test chip (TEG chip manufactured by Walts, CC80 (model I), chip size 7.3 mm × 7.3 mm, number of bumps 1048) was prepared as a semiconductor device. As a base material, a printed wiring board provided with a copper conductor wiring was prepared. As the flip chip bonder, model number FC3000S manufactured by Toray Engineering Co., Ltd. was used.

The base material was fixed on the stage of the flip chip bonder while being heated to the range of 60 to 100 ° C. On this base material, 3.0 to 4.0 mg of the sealing acrylic resin composition of each Example and Comparative Example was applied with a dispenser. The position where the semiconductor chip is held by the bonding head of the flip chip bonder, the bonding head is brought close to the stage while the bonding head is heated to 130 ° C., and the semiconductor chip is coated with the acrylic resin composition for sealing on the base material. The bump electrode of the semiconductor chip and the electrode pad of the base material were arranged while aligning with each other. The semiconductor chip was pressed against the substrate for 0.5 seconds. Subsequently, while applying a load of 60 N from the bonding head to the semiconductor chip, the temperature of the bonding head was raised to the maximum temperature of 260 ° C. over 1.5 seconds. Subsequently, the temperature of the bonding head was held at the maximum temperature reached for 2 seconds, the holding of the semiconductor chip by the bonding head was released, and the bonding head was separated from the stage. The time from placing the semiconductor chip on the substrate until the bonding head was separated from the stage was set to about 4 seconds. As a result, a semiconductor device for testing was obtained.

The presence or absence of voids in the cured product in this semiconductor device was investigated using an ultrasonic flaw detector (SAT). The results were evaluated as follows.
A: 0 voids.
B: 1 to 5 voids.

(2) Solder wetness evaluation As a semiconductor device, a test chip (TEG chip manufactured by Walts, MB50 (Type-B), chip size 7.3 mm × 7.3 mm, number of bumps) having a smaller number of bumps than in the case of the above void evaluation. A semiconductor device for testing was obtained by the same method as in the case of void evaluation, except that the load at the time of mounting was changed to 30 N according to the number of bumps of the semiconductor device using 544). This semiconductor device was cut at a surface including a connecting portion between the bump electrode of the semiconductor chip and the electrode pad of the base material, and then the cross section was polished. This cross section was observed by SEM, and the result was evaluated as follows.
A: There is a gap of 5 μm or less between the tip of the pillar in the bump electrode and the electrode pad, and this gap is filled with solder bumps. The sides of the electrode pads are wet with solder bumps. No particles of the inorganic filler are found between the electrode pad and the solder bump. B: There is a gap of 5 μm or less between the tip of the pillar in the bump electrode and the electrode pad, and this gap is filled with solder bumps. The sides of the electrode pads are not wet with solder bumps. No particles of the inorganic filler are found between the electrode pad and the solder bump.
C: There is a gap of 5 μm or less between the tip of the pillar in the bump electrode and the electrode pad, and this gap is filled with solder bumps. Particles of the inorganic filler are found to be caught between the electrode pad and the solder bump.
C to B: There is a gap of more than 5 μm between the tip of the pillar in the bump electrode and the electrode pad, and this gap is filled with solder bumps. The sides of the electrode pads are not wet with solder bumps. No particles of the inorganic filler are found between the electrode pad and the solder bump.

(3) Adhesion Evaluation Acrylic resin composition for sealing obtained in each Example and Comparative Example was applied on a ceramic substrate, and a 2 mm square silicon chip coated with a silicon nitride film was placed on the coating. In this state, the sealing acrylic resin composition was cured by heating at 150 ° C. for 2 hours. For the sample obtained in this way, the bond strength between the silicon chip and the ceramic substrate at 260 ° C. was measured using the Bond Tester Series 4000 manufactured by Arctech, and the fracture mode when the silicon chip was peeled off from the ceramic substrate. It was confirmed. The results were evaluated as follows.
A: Bond strength of 20 MPa or more, fracture mode is cohesive fracture.
B: Bond strength 10 MPa or more and 20 MPa, fracture mode is cohesive fracture.
C: Bond strength less than 10 MPa.

When the bonding strength was 10 MPa or more and less than 20 MPa and the fracture mode was fracture at the interface of the silicon nitride film, it was evaluated as C to B.

(4) Reliability Evaluation Using the sealing acrylic resin compositions of each Example and Comparative Example, a semiconductor device for testing was obtained by the same method as in the case of void evaluation. This semiconductor device was treated under the moisture absorption treatment conditions of MSL Lv2aA (60 ° C., 60% RH, 120 hours), and then passed through a reflow furnace having a peak temperature of 260 ° C. three times. Subsequently, the presence or absence of peeling of the interface between the cured product and the semiconductor chip and the base material in the semiconductor device was investigated using an ultrasonic flaw detector (SAT). The same test was performed four times for each example and comparative example. The results were evaluated as follows.
A: No peeling was observed in all four tests.
B: Peeling was observed only in one test.
C: Peeling was observed in two or more tests.

(5) Migration resistance evaluation An acrylic resin composition for encapsulation of each Example and Comparative Example was applied to an evaluation substrate provided with a copper comb electrode having a line width of 50 μm and a line spacing of 50 μm so as to cover the comb electrode. , A film having a thickness of 500 μm was formed. The film was cured by heating at 125 ° C. for 2 hours. Subsequently, while applying a voltage of 50 V to the comb-shaped electrode of the evaluation substrate with an insulation resistance measuring device (ETAC, model number SIR13), the evaluation substrate was subjected to an advanced accelerated life test device (ESPEC, model number EHS-221M). ) Was exposed to an atmosphere of 85 ° C. and 85% RH. It was confirmed whether or not migration occurred in this evaluation substrate when it was treated with the advanced accelerated life test apparatus for 500 hours and when it was treated for 1000 hours. The same test was performed three times for each example and comparative example. The results were evaluated as follows.
A: No significant migration was observed in either the case of treatment for 500 hours or the case of treatment for 1000 hours.
B: No migration was observed after 500 hours of treatment, but migration occurred at many locations throughout the comb electrode after 1000 hours of treatment.
C: After 500 hours of treatment, migration occurred at many locations over the entire comb electrode.

No migration was observed after 500 hours of treatment, and B to A was evaluated when migration was observed only in a part of the comb electrode after 1000 hours of treatment.

(5) Evaluation of Insulation Resistance Deterioration Resistance To an evaluation substrate provided with a copper comb electrode having a wire width of 100 μm and a line spacing of 100 μm, an acrylic resin composition for encapsulation of each Example and Comparative Example was applied so as to cover the comb electrode. Then, a film having a thickness of 500 μm was formed. The film was cured by heating at 125 ° C. for 2 hours. Subsequently, while applying a voltage of 100 V to the comb-shaped electrode of the evaluation substrate with an insulation resistance measuring device (ETAC, model number SIR13), the evaluation substrate was subjected to a high acceleration life test device (ESPEC, model number EHS-221M). ) Was exposed to an atmosphere of 130 ° C. and 85% RH. During this time, monitoring the electrical resistance value measured by the insulation resistance tester, the electric resistance was confirmed processing time at high accelerated life test apparatus takes to drop to 10 ⁶ Omega. The same test was performed three times for each Example and Comparative Example, and the average value of the obtained processing times was calculated. The results were evaluated as follows.
A: The average processing time is 200 hours or more.
B: The average processing time is 100 hours or more and less than 200 hours.
C: The average processing time is less than 100 hours.

Even if the average value of the processing time was 200 hours or more, when the difference between the maximum value and the minimum value of the processing time was 50 hours or more, it was evaluated as B to A.

(6) Evaluation of the presence or absence of agglomerates Using a 50 μm grind gauge, the presence, number, and size of agglomerates in the sealing acrylic resin composition of each Example and Comparative Example were confirmed. The same test was performed three times in each example and comparative example. The results were evaluated as follows.
A: In the three tests, no agglomerates of 10 μm or more were observed.
B: Only aggregates of 10 μm or more and less than 30 μm were observed, and the average number of these aggregates in the three tests was less than 5.

When one or more agglomerates of 30 μm or more are observed in average number, or when only agglomerates of 10 μm or more and less than 30 μm are observed and the average number is 5 or more and less than 10 pieces, B to A I evaluated it.

1 Semiconductor device 2 Base material 21 Conductor wiring 3 Semiconductor chip 33 Bump electrode 42 Encapsulant

Claims (8)

Contains a compound having a (meth) acryloyl group, a thermal radical polymerization initiator, an organic acid, and a compound having a function of capturing an organic acid.
The compound having a function of capturing an organic acid contains one or more components selected from the group consisting of a Zr-Bi-based ion scavenger, a Zr-Mg-Al-based ion scavenger, and a Zr-based ion scavenger. Acrylic resin composition for sealing. The acrylic resin composition for sealing according to claim 1, wherein the compound having a function of capturing the organic acid has a function of capturing the ionized organic acid. The acrylic resin composition for sealing according to claim 1 or 2, which contains an inorganic filler containing at least one of silica and alumina. The seal according to any one of claims 1 to 3, wherein the compound having a function of capturing the organic acid is in the range of 0.01 to 15% by mass with respect to the entire sealing acrylic resin composition. Acrylic resin composition for stopping. The sealing acrylic resin composition according to any one of claims 1 to 4, wherein the organic acid is in the range of 0.1 to 10% by mass with respect to the entire sealing acrylic resin composition. The acrylic resin composition for sealing according to any one of claims 1 to 5, which is liquid at room temperature. A base material, a semiconductor chip mounted face-down on the base material, and a sealing material for sealing a gap between the base material and the semiconductor chip are provided, and the sealing material is claimed 1. A semiconductor device comprising a cured product of the acrylic resin composition for sealing according to any one of 6 to 6. Prepare a base material with conductor wiring and a semiconductor chip with bump electrodes.
The sealing acrylic resin composition according to any one of claims 1 to 6 is arranged on the base material.
The semiconductor chip is arranged at a position on the base material where the sealing acrylic resin composition is arranged, and the bump electrode is arranged on the conductor wiring.
By heating the sealing acrylic resin composition and the bump electrode, the sealing acrylic resin composition is cured to form a sealing material, and the bump electrode and the conductor wiring are electrically connected. A method of manufacturing a semiconductor device including