TW201517228A - Semiconductor device - Google Patents

Abstract

A semiconductor device (100) is provided with: a semiconductor chip (10) that is provided with an electrode pad (12); and a wire (30) that is electrically connected to the electrode pad (12). The wire (30) is configured from a first metal material that is mainly composed of Ag and contains Pd. The electrode pad (12) is configured from a second metal material that is mainly composed of Al. An alloy layer that contains Ag, Al and Pd is formed on a joint part (40) of the wire (30) and the electrode pad (12).

Description

Semiconductor device

The present invention relates to a semiconductor device.

The semiconductor wafer is electrically connected to the lead frame or the substrate, for example, using a bonding wire. There have been various studies on the technique of bonding wires, for example, those described in the cited patent documents 1 to 5.

Patent Document 1 describes a wire material in which a nitride of an additive element group is dispersed on a surface of a pure metal such as gold, silver or copper, a gold-silver alloy, a gold-copper alloy or a gold-palladium alloy. Patent Documents 2 and 3 describe a technique for a bonding wire having a silver wire and a gold film covering the silver wire. Patent Document 4 describes an Ag bonding wire containing Au and Bi. Patent Document 5 discloses a bonding wire for a semiconductor having a core material containing one or more elements of Cu, Au, and Ag as a main component, and a core layer having Pd as a main component.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2008-174779

Patent Document 2: Japanese Patent Laid-Open Publication No. 2001-196411

Patent Document 3: Japanese Patent Laid-Open Publication No. 2001-176912

Patent Document 4: Japanese Patent Laid-Open Publication No. 2012-49198

Patent Document 5: International Publication No. 2010/106851

The connection terminals of the electrode pads of the semiconductor wafer and the substrate are electrically connected to each other, for example, via wires. In such a semiconductor device, a lead wire made of a metal material having a main component of Ag may be bonded to an electrode pad provided on a semiconductor wafer and made of a metal material having a main component of Al. In this case, there is a case where good bonding reliability cannot be obtained between the wire and the electrode pad.

According to the invention, there is provided a semiconductor device comprising: a semiconductor wafer including an electrode pad; and a lead electrically connected to the electrode pad, wherein the lead wire is made of a first metal material containing a main component of Ag and containing Pd, and the electrode pad It is composed of a second metal material having a main component of Al, and an alloy layer containing Ag, Al, and Pd is formed at a joint portion between the lead wire and the electrode pad.

According to the present invention, the bonding reliability of the wire and the electrode pad can be improved.

10‧‧‧Semiconductor wafer

12‧‧‧electrode pads

20‧‧‧Substrate

22‧‧‧Connecting terminal

24‧‧‧ Wafer holder

30‧‧‧Wire (bonding wire)

30a‧‧‧ front end

32‧‧‧ alloy layer

34‧‧‧Wire

40‧‧‧ joints

50‧‧‧Protective film

60‧‧‧ sealing resin

62‧‧‧ solder balls

100‧‧‧Semiconductor device

The above and other objects, features and advantages of the present invention will become more apparent from

Fig. 1 is a plan view showing a semiconductor device of a first embodiment.

Fig. 2 is a cross-sectional view showing the semiconductor device shown in Fig. 1;

Fig. 3 is an enlarged view of the joint portion shown in Fig. 2;

4 is a plan view showing a first modification of the semiconductor device shown in FIG. 1.

Fig. 5 is a cross-sectional view showing a second modification of the semiconductor device shown in Fig. 1;

The embodiments will be described below using the drawings. In the drawings, the same components are denoted by the same reference numerals, and the description is omitted as appropriate.

Fig. 1 is a plan view showing a semiconductor device 100 of the present embodiment. FIG. 2 is a cross-sectional view showing the semiconductor device 100 shown in FIG. 1.

The semiconductor device 100 of the present embodiment includes a semiconductor wafer 10 and a wire 30. The semiconductor wafer 10 is provided with an electrode pad 12. The wire 30 is electrically connected to the electrode pad 12. The wire 30 is composed of a first metal material having a main component of Ag and containing Pd. The electrode pad 12 is made of a second metal material whose main component is Al. An alloy layer containing Ag, Al, and Pd or an alloy layer containing Ag, Al, Pd, and Au is formed in the joint portion 40 between the wire 30 and the electrode pad 12.

According to the present embodiment, the bonding portion 40 of the electrode pad 30 made of the first metal material containing the main component of Ag and containing Pd and the electrode pad 12 made of the second metal material having the main component Al is formed to contain Ag, Al. And an alloy layer of Pd or an alloy layer containing Ag, Al, Pd, and Au. The present inventors have found that in such a case, the joint portion 40 excellent in the balance between moisture resistance reliability and high-temperature storage characteristics can be realized. Thereby, the bonding reliability between the wire 30 and the electrode pad 12 can be improved.

The configuration of the semiconductor device 100 of the present embodiment and the method of manufacturing the semiconductor device 100 will be described in detail below.

The semiconductor device 100 of the present embodiment includes a substrate 20 and a semiconductor wafer 10 mounted on the substrate 20. The substrate 20 and the semiconductor wafer 10 are via a wire 30 (bonding wire) And electrically connected to each other. In FIG. 1, the semiconductor device 100 constitutes, for example, a semiconductor package in which a semiconductor wafer 10 is mounted on a substrate 20.

The example shown in FIG. 1 discloses a case where a semiconductor wafer 10 is mounted on a substrate 20. On the other hand, the semiconductor device 100 of the present embodiment may include, for example, a plurality of semiconductor wafers 10 laminated on the substrate 20. In this case, each of the semiconductor wafers 10 is electrically connected to the substrate 20 via, for example, a wire 30.

The substrate 20 is not particularly limited as long as it can be recognized by a manufacturer as a member capable of mounting a semiconductor wafer, and is, for example, a wiring board such as an interposer or a mother board, a lead frame, or another semiconductor wafer.

1 and 2 illustrate the case where the substrate 20 is an interposer. In this case, a plurality of solder balls 62 are provided on the other surface of the substrate 20 opposite to one surface on which the semiconductor wafer 10 is mounted. The semiconductor device 100 including the substrate 20 and the semiconductor wafer 10 is mounted on another wiring substrate via solder balls 62, for example.

The substrate 20 is provided with a connection terminal 22 . One end of the wire 30 is joined to the surface portion of the connection terminal 22.

The connection terminal 22 is provided, for example, on one surface of the semiconductor wafer 10 mounted on the substrate 20. On one surface of the substrate 20, for example, a plurality of connection terminals 22 are provided. In this case, a plurality of connection terminals 22 are provided, for example, along the outer edge of the semiconductor wafer 10. In the example shown in Fig. 1, the connection terminal 22 is provided on an electrode pad on the substrate 20 constituting the interposer.

At least a surface portion of the connection terminal 22 is made of, for example, a material whose main component is Au.

Further, when the substrate 20 is a lead frame, the surface portion of the connection terminal 22 is made of, for example, Ag or a laminated film in which a Ni layer, a Pd layer, and an Au layer are sequentially laminated.

The semiconductor wafer 10 is mounted on the substrate 20. Examples of the semiconductor wafer 10 include an integrated circuit, a large-scale integrated circuit, and a solid-state imaging device. The semiconductor wafer 10 is then attached to one side of the substrate 20, for example, via a film-like or paste-like die attach material.

The semiconductor wafer 10 is provided with an electrode pad 12. The other end of the wire 30 opposite to one end joined to the connection terminal 22 is joined to the surface portion of the electrode pad 12.

The electrode pad 12 is provided, for example, on the other surface of the semiconductor wafer 10 opposite to one side of the substrate 20. On the other side of the semiconductor wafer 10, for example, a plurality of electrode pads 12 are provided. In this case, a plurality of electrode pads 12 are disposed, for example, along the outer edge of the semiconductor wafer 10.

The electrode pad 12 is made of a second metal material whose main component is Al. In this case, the surface portion of the electrode pad 12 that is bonded to the wire 30 is made of a second metal material. In the present embodiment, the second metal material constituting the electrode pad 12 may contain other metal materials such as Ni, Au, Pd, Ag, Cu, Si, or Pt in addition to Al.

In the present embodiment, the Al content in the second metal material constituting the electrode pad 12 is, for example, 90% by weight or more and 100% by weight or less.

The wire 30 is electrically connected to the connection terminal 22 and the electrode pad 12. In the present embodiment, for example, one end of the wire 30 is joined to the connection terminal 22, and the other end opposite to the one end is joined to the electrode pad 12. A joint portion 40 formed by joining the end portion 30a of the lead wire 30 and the electrode pad 12 is formed. In the example shown in FIG. 1, a plurality of electrode pads 12 are provided on the semiconductor wafer 10, and a plurality of connection terminals 22 are provided on the substrate 20. In this case, a plurality of wires 30 for electrically connecting the electrode pads 12 and the respective connection terminals 22 to each other are provided.

In the present embodiment, the diameter of the wire 30 is, for example, 15 μm or more and 25 μm or less, and particularly preferably 18 μm or more and 20 μm or less.

The wire 30 is composed of a first metal material having a main component of Ag and containing Pd. In this case, the end portion 30a is made of the first metal material before the wire 30 is joined to the electrode pad 12. In the present embodiment, the first metal material constituting the lead wire 30 may contain, for example, Au in addition to Ag and Pd. Thereby, the moisture resistance reliability of the joint portion 40 can be more effectively improved.

The content of Ag in the first metal material constituting the wire 30 is preferably 85% by weight or more and 99.5% by weight or less, more preferably 85% by mass or more and 96% by mass or less. Thereby, the manufacturing cost can be reduced, the moisture resistance reliability and the high-temperature storage characteristics of the joint portion 40 can be more effectively improved, and the joint reliability between the wire 30 and the electrode pad 12 can be improved.

Further, the Pd content in the first metal material constituting the wire 30 is preferably 0.5% by weight or more and 15% by weight or less, more preferably 2% by weight or more and 10% by weight or less, still more preferably 3% by weight or more and 6 parts by weight. Below weight%. Thereby, an increase in manufacturing cost can be suppressed and moisture resistance reliability or high temperature storage characteristics can be more effectively improved. When the first metal material contains Au, the Au content in the first metal material is, for example, more than 0% by weight and 10% by weight or less, more preferably 2% by weight or more and 10% by weight or less. Thereby, the bondability of the wires 30 can be improved. However, when the Ag content is 94% by weight or more, Au may not be used.

FIG. 3 is an enlarged view of the joint portion 40 shown in FIG. 2. As shown in FIG. 3, on the other surface of the semiconductor wafer 10, for example, a protective film 50 made of polyimide or the like is formed. The protective film 50 is provided with an opening so that the surface of the electrode pad 12 is exposed.

An alloy layer 32 containing Ag, Al, and Pd is formed on the joint portion 40 of the wire 30 and the electrode pad 12. Thereby, the joint portion 40 excellent in balance between moisture resistance reliability and high-temperature storage characteristics can be achieved. The alloy layer 32 containing Ag, Al, and Pd can be appropriately controlled, for example, by appropriately controlling the composition of the first metal material constituting the wire 30 and the composition of the second metal material constituting the electrode pad 12. And a method of bonding the wire 30 to the electrode pad 12 is formed.

The composition ratio of Ag, Al, and Pd in the alloy layer 32 may be different from each other in, for example, the respective regions included in the alloy layer 32. The alloy layer 32 of the present embodiment is provided, for example, in such a manner that the composition of Ag and Pd at one end of the wire 30 side is relatively high and the composition of Al is relatively lower than that of the other end portion on the side of the electrode pad 12. Further, the alloy layer 32 in the present embodiment may have a region where the other end portion on the electrode pad 12 side does not contain Pd, but it is preferable not to have the region.

In the case where Au is contained in the first metal material constituting the wire 30, the alloy layer 32 in the present embodiment is provided, for example, in such a manner that it is located on the wire 30 as compared with the other end portion on the electrode pad 12 side. The composition of Ag, Pd, and Au at one end is relatively high and the composition of Al is relatively low.

In the present embodiment, the lead wire 30 and the electrode pad 12 are joined to each other via the alloy layer 32 containing Ag, Al, and Pd or Ag, Al, Pd, and Au formed in the joint portion 40.

In the example shown in FIG. 3, the alloy layer 32 is provided in a layered or island shape on the end face of the wire 30 joined to the electrode pad 12. At this time, the end face of the wire 30 joined to the electrode pad 12 coincides with the bottom surface of the front end portion 30a. Further, the shape of the alloy layer 32 is not limited thereto, and may be various shapes.

The semiconductor wafer 10 and the wires 30 are sealed by, for example, a sealing resin 60 made of a cured product of an epoxy resin composition. In this case, the joint portion 40 between the wire 30 and the electrode pad 12 is also sealed by the cured product of the above epoxy resin composition.

The cured product of the epoxy resin composition that seals the semiconductor wafer 10 and the wires 30 may contain, for example, an organic sulfur compound. In this case, the cured product of the epoxy resin composition can be excellent in adhesion to the lead wire 30 composed of the semiconductor wafer 10 and the first metal material having the main component Ag. Therefore, the sealing resin 60 composed of the cured product of the epoxy resin composition can be suppressed Peeling or the like between the semiconductor wafer 10 and the wires 30.

The sulfur content of the organic sulfur compound derived from the cured product of the epoxy resin composition is, for example, preferably 1 ppm or more and 400 ppm or less. Here, the sulfur content in the cured product of the epoxy resin composition is set to be derived from the sulfur content of the organic sulfur compound. The sulfur content is, for example, quantified in the following manner. First, about 5 mg of the cured product of the epoxy resin composition was weighed, and it was burned in a flask filled with oxygen inside, and the combustion gas generated by the 5% potassium hydroxide solution was absorbed. Then, the amount of sulfate ion in the 5% potassium hydroxide solution measured by ion chromatography was converted into the sulfur content in the epoxy resin composition.

By setting the sulfur content to 1 ppm or more, the adhesion of the cured product of the epoxy resin composition to the wire 30 or the semiconductor wafer 10 can be effectively improved. Moreover, by setting the sulfur content to 400 ppm or less, the high-temperature storage characteristics of the joint portion 40 sealed by the cured product of the epoxy resin composition can be improved. Further, the sulfur content in the cured product of the epoxy resin composition can be adjusted by appropriately controlling the components constituting the epoxy resin composition or the preparation method.

The cured product of the epoxy resin composition for sealing the semiconductor wafer 10 and the lead wire 30 has a pH of, for example, preferably 4 or more and 7 or less, more preferably 4.5 or more and 6.5 or less. In this case, it is possible to suppress the joint portion 40 from being corroded by the cured product of the epoxy resin composition. Therefore, the bonding reliability between the wire 30 and the electrode pad 12 can be improved.

Further, the pH of the cured product of the epoxy resin composition is adjusted by appropriately controlling the components constituting the epoxy resin composition or the preparation method.

Hereinafter, the epoxy resin composition constituting the sealing resin 60 will be described in detail. The epoxy resin composition contains (A) an epoxy resin and (B) a hardener.

((A) epoxy resin)

The (A) epoxy resin contained in the epoxy resin composition can be used for all monomers, oligomers, and polymers having two or more epoxy groups in one molecule, and its molecular weight or molecular structure is not particularly limited.

In the present embodiment, examples of the (A) epoxy resin include a biphenyl type epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a tetramethyl bisphenol F type epoxy. Bisphenol type epoxy resin such as resin; bismuth type epoxy resin; phenol novolak type epoxy resin, phenol novolac type epoxy resin and other novolak type epoxy resin; trisphenol methane type epoxy resin, alkyl group modification a polyfunctional epoxy resin such as a trisphenol methane type epoxy resin; a phenol aralkyl type epoxy resin having a phenyl group skeleton; and an aralkyl type such as a phenol aralkyl type epoxy resin having a phenyl group extending; Epoxy resin; dihydroxynaphthalene type epoxy resin; naphthol type epoxy resin such as epoxy resin obtained by etherification of dihydroxynaphthalene dimer glycidyl; triglycidyl isocyanurate, isocyanuric acid Allyl diglycidyl ester, etc. The epoxy resin of the core; the phenolic epoxy resin which is a bridged cyclic hydrocarbon compound, such as a dicyclopentadiene-modified phenol type epoxy resin, may be used alone or in combination of two or more. Among these, a bisphenol type epoxy resin such as a biphenyl type epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a tetramethyl bisphenol F type epoxy resin is preferable. And the bismuth type epoxy resin has crystallinity.

As the epoxy resin (A), a ring containing an epoxy resin represented by the following formula (1), an epoxy resin represented by the following formula (2), and a ring represented by the following formula (3) is preferably used. At least one of the group consisting of oxygen resins.

In the formula (1), Ar ¹ represents a phenylene group or a naphthyl group, and when Ar ¹ is a naphthyl group, the glycidyl ether group may be bonded to any of the α position and the β position. Ar ² represents any of a phenyl group, a biphenyl group or a naphthyl group. R ⁵ and R ⁶ each independently represent a hydrocarbon group having 1 to 10 carbon atoms. g is an integer from 0 to 5, and h is an integer from 0 to 8. n ³ represents the degree of polymerization, and the average value thereof is 1 to 3.

In the formula (2), the plurality of R ⁹ present independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. n ⁵ represents the degree of polymerization, and the average value thereof is 0 to 4.

In the formula (3), the plurality of R ¹⁰ and R ^{11 present} independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. n ⁶ represents the degree of polymerization, and the average value thereof is 0 to 4.

The content of the epoxy resin (A) is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 8% by mass or more based on the total amount of the epoxy resin composition. By this, it can be suppressed The wire is broken due to an increase in the viscosity of the epoxy resin composition. In addition, the content of the epoxy resin (A) is preferably 18% by mass or less, more preferably 13% by mass or less, and still more preferably 11% by mass or less based on the total amount of the epoxy resin composition. Thereby, it is possible to suppress a decrease in moisture resistance reliability due to an increase in water absorption rate and the like.

((B) hardener)

The (B) hardener contained in the epoxy resin composition can be roughly classified into three types, an addition polymerization type hardener, a catalyst type hardener, and a condensation type hardener.

Examples of the addition polymerization type curing agent used for the (B) curing agent include di-ethyltriamine (DETA), tri-ethyltetramine (TETA), m-xylylenediamine (MXDA), and the like. Aromatic polyamines, aromatic polyamines such as diaminodiphenylmethane (DDM), m-phenylenediamine (MPDA), and diaminodiphenyl hydrazine (DDS), in addition to dicyandiamide (DICY), organic a polyamine compound such as diterpene acid; an alicyclic acid anhydride such as hexahydrophthalic anhydride (HHPA) or methyltetrahydrophthalic anhydride (MTHPA), trimellitic anhydride (TMA), ortho-benzene Anhydride such as aromatic acid anhydride such as tetracarboxylic acid dianhydride (PMDA) or benzophenone tetracarboxylic dianhydride (BTDA); phenol resin curing agent such as novolak type phenol resin or polyvinyl phenol; polysulfide and sulfur a polythiol compound such as an ester or a thioether; an isocyanate compound such as an isocyanate prepolymer or a blocked isocyanate; an organic acid such as a carboxylic acid-containing polyester resin.

(B) The catalyst-type hardener used for the hardener, for example, three grades such as dimethylbenzylamine (BDMA) and 2,4,6-tris-dimethylaminomethylphenol (DMP-30) An amine compound; an imidazole compound such as 2-methylimidazole or 2-ethyl-4-methylimidazole (EMI24); a Lewis acid such as a BF3 complex or the like.

(B) A condensing type hardener used for a hardener, for example, a soluble phenol An aldehyde type phenol resin; a urea resin such as a methylol-containing urea resin; a melamine resin such as a hydroxymethyl group-containing melamine resin or the like.

Among these, a phenol resin-based curing agent is preferred from the viewpoint of improving the balance between flame resistance, moisture resistance, electronic properties, curability, and storage stability. The phenol resin-based curing agent can be used for all monomers, oligomers, and polymers having two or more phenolic hydroxyl groups in one molecule, and the molecular weight and molecular structure thereof are not particularly limited.

(B) The phenol resin-based curing agent used for the curing agent, for example, a novolak type resin such as a phenol novolak resin, a cresol novolak resin, or a bisphenol novolak; a polyvinyl phenol; a trisphenol methane type phenol resin; a polyfunctional phenol resin; a modified phenol resin such as a terpene-modified phenol resin or a dicyclopentadiene-modified phenol resin; a phenol aralkyl resin having a phenyl group and/or a phenyl group extending; An aralkyl type resin such as a naphthol aralkyl resin which stretches a phenyl group and/or a biphenyl group; a bisphenol compound such as bisphenol A or bisphenol F, etc., which may be used alone or in combination 2 More than one species.

(B) A curing agent, and at least one curing agent selected from the group consisting of compounds represented by the following formula (4) is preferably used.

In the formula (4), Ar ³ represents a phenyl or a naphthyl group, and when Ar ³ is a naphthyl group, the hydroxy group may be bonded to any of the α-position and the β-position. Ar ⁴ represents any of a phenyl group, a biphenyl group or a naphthyl group. R ⁷ and R ⁸ each independently represent a hydrocarbon group having 1 to 10 carbon atoms. i is an integer from 0 to 5, and j is an integer from 0 to 8. n ⁴ represents the degree of polymerization, and the average value thereof is 1 to 3.

(B) The content of the curing agent is preferably 2% by mass or more, more preferably 3% by mass or more, and still more preferably 6% by mass or more based on the entire epoxy resin composition. Thereby, an epoxy resin composition having sufficient fluidity can be obtained. In addition, the content of the hardener (B) is preferably 15% by mass or less, more preferably 11% by mass or less, and still more preferably 8% by mass or less based on the total amount of the epoxy resin composition. Thereby, it is possible to reduce the deterioration of the moisture resistance reliability caused by the increase in the water absorption rate.

In the case where a phenol resin-based curing agent is used as the (B) hardener, the blend ratio of the (A) epoxy resin to the (B) hardener as the phenol resin-based hardener is preferably all of the epoxy resins. The equivalent ratio (EP)/(OH) of the number of epoxy groups (EP) to the phenolic hydroxyl group (OH) of all the phenol resin-based curing agents is 0.8 or more and 1.3 or less. By setting the equivalent ratio to the above range, it is possible to suppress a decrease in the hardenability of the epoxy resin composition or a decrease in the physical properties of the cured epoxy resin.

The epoxy resin composition may also contain (C) a filler, (D) a neutralizer, (E) a hardening accelerator, or (F) an organic sulfur compound, as needed.

((C) filler material)

(C) The filler material can be generally used for an epoxy resin composition for semiconductor sealing, and examples thereof include: molten spherical cerium oxide, melt-crushed cerium oxide, crystalline cerium oxide, talc, alumina, and titanium white. , inorganic filler materials such as tantalum nitride, organic polyfluorene powder, polyethylene powder and other organic filler materials. Among these, it is particularly preferable to use molten spherical cerium oxide. These fillers may be used alone or in combination of two or more.

As the shape of the (C) filler, it is preferable to have a spherical shape and a particle as much as possible in order to suppress an increase in the melt viscosity of the epoxy resin composition and to increase the content of the filler. The degree of distribution is broad. Further, the (C) filler material may be surface-treated by a coupling agent. Further, if necessary, the (C) filler may be treated in advance using an epoxy resin or a phenol resin. The treatment method at this time may be a method of removing the solvent after mixing with a solvent, or a method of directly adding to a filler and mixing the mixture using a mixer.

The content of the (C) filler is preferably 65 mass% or more, and more preferably 75, based on the entire epoxy resin composition, from the viewpoint of the filling property of the epoxy resin composition and the reliability of the semiconductor device. The mass% or more is more preferably 80% by mass or more. Thereby, low moisture absorption and low thermal expansion property can be improved, and moisture resistance reliability can be improved. In addition, the content of the (C) filler is preferably 93% by mass or less, more preferably 91% by mass or less, even more preferably 86%, based on the entire epoxy resin composition. Below mass%. As a result, it is possible to reduce the decrease in fluidity, cause a filling failure or the like during molding, or cause a problem such as a flow of a wire in a semiconductor device due to high viscosity.

((D) Neutralizer)

(D) Neutralizing agent, which can be used for neutralizing an epoxy resin composition or an acidic corrosive gas generated by heating the sealing resin 60 as a cured product. Thereby, corrosion (oxidation degradation) of the bonding portion 40 of the wire 30 and the electrode pad 12 of the semiconductor wafer 10 can be suppressed. (D) The neutralizing agent can be, for example, an alkali metal salt, in particular, at least one selected from the group consisting of a compound containing a calcium element, a compound containing an aluminum element, and a compound containing a magnesium element.

(D) The calcium-containing compound used in the neutralizing agent may, for example, be calcium carbonate, calcium borate or calcium metasilicate. Among these, calcium carbonate is preferred from the viewpoint of the content of impurities, water resistance and low water absorption, and more preferably precipitated calcium carbonate synthesized by a carbon dioxide reaction method.

(D) The compound containing an aluminum element used for the neutralizing agent may, for example, be aluminum hydroxide or bauxite. Among these, aluminum hydroxide is preferred. Further, the aluminum hydroxide used in the (D) neutralizing agent is more preferably a low-sodium aluminum hydroxide synthesized by a two-stage Bayer process.

(D) The compound containing a magnesium element used for the neutralizing agent may, for example, be hydrotalcite, magnesium oxide or magnesium carbonate. Among these, hydrotalcite represented by the following formula (5) is particularly preferably used from the viewpoint of the impurity content and the low water absorption rate.

M _a Al _b (OH) _2a+3b-2c (CO ₃ ) _c . mH ₂ O (5)

(In the formula (5), M represents a metal element containing at least Mg; a, b, and c are each an integer satisfying 2≦a≦8, 1≦b≦3, 0.5≦c≦2, and m is an integer of 0 or more )

Examples of the hydrotalcite used as the (D) neutralizing agent include Mg ₆ Al ₂ (OH) ₁₆ (CO ₃ ). mH ₂ O, Mg ₃ ZnAl ₂ (OH) ₁₂ (CO ₃ ). mH ₂ O, Mg _4.3 Al ₂ (OH) _12.6 (CO ₃ ). mH ₂ O and the like.

The content of the (D) neutralizing agent is preferably 0.01% by mass or more and 10% by mass or less based on the total amount of the epoxy resin composition. By setting the content of the (D) neutralizing agent to 0.01% by mass or more, the effect of adding the neutralizing agent (D) can be sufficiently exhibited, and the corrosion of the joint portion 40 of the wire 30 and the electrode pad 12 can be more surely prevented (oxidation). Deterioration) improves the high temperature storage characteristics of the semiconductor device 100. In addition, when the content of the (D) neutralizing agent is 10% by mass or less, the moisture absorption rate can be lowered, so that the weld crack resistance tends to be improved. In particular, when calcium carbonate or hydrotalcite is used as the anticorrosive agent, the content thereof is preferably 0.05% by mass or more and 2% by mass or less based on the entire viewpoint of the epoxy resin composition.

((E) hardening accelerator)

(E) The hardening accelerator is used to promote (A) epoxy group epoxy resin and (B) hardener (for example) For example, a crosslinking reaction of a phenolic hydroxyl group of a phenol resin-based curing agent may be used, and those generally used for an epoxy resin composition for semiconductor sealing can be used. (E) The hardening accelerator may, for example, be an organophosphine, a tetrasubstituted phosphonium compound, a phosphobetaine compound, an adduct of a phosphine compound and a hydrazine compound, or a compound containing a phosphorus atom such as an adduct of a hydrazine compound and a decane compound. Illustrated as a quaternary or tertiary amine of 1,8-diazabicyclo(5,4,0)undecene-7, dimethylbenzylamine, 2-methylimidazole or the like, or even a quaternary salt of the above hydrazine or amine The compound containing a nitrogen atom or the like may be used alone or in combination of two or more.

The content of the (E) curing accelerator is preferably 0.05% by mass or more, and more preferably 0.1% by mass or more based on the entire epoxy resin composition. Thereby, the fall of hardenability can be suppressed. In addition, the content of the (E) curing accelerator is preferably 1% by mass or less, and more preferably 0.5% by mass or less based on the total amount of the epoxy resin composition. Thereby, the fluidity can be suppressed from being lowered.

((F) organic sulfur compound)

(F) The organic sulfur compound is a compound containing one or more sulfur atoms in one molecule. By including the (F) organic sulfur compound in the epoxy resin composition, the adhesion of the epoxy resin composition to the semiconductor wafer 10 and the wires 30 can be improved. (F) The organic sulfur compound may, for example, be a mercapto compound such as 3-mercaptopropyltrimethoxydecane or a mercapto compound having a triazole skeleton such as 3-amino-5-mercapto-1,2,4-triazole. a dithiane compound such as trans-4,5-dihydroxy-1,2-dithiane, a 2-(methylthio)-2-thiazoline compound, or a benzothiazole such as 2-mercaptobenzothiazole The thiol-containing alcohol, such as a compound, a 2-mercaptoethanol or a 3-mercapto-1,2-propanediol, may be used alone or in combination of two or more.

Among these, a mercaptodecane compound such as 3-mercaptopropyltrimethoxydecane is preferably used as the (F) organic sulfur compound. Thereby, the adhesion to the semiconductor wafer 10 or the wires 30 can be achieved. An epoxy resin composition excellent in balance of high-temperature storage characteristics. Further, a mercaptodecane compound such as 3-mercaptopropyltrimethoxydecane also has a coupling agent function.

The content of the organic sulfur compound (F) is preferably 0.05% by mass or more and 1% by mass or less, and particularly preferably 0.1% by mass or more and 0.5% by mass or less based on the total amount of the epoxy resin composition. Thereby, the sulfur content in the cured product of the epoxy resin composition can be an epoxy resin composition which is suitable for achieving a balance between adhesion and high-temperature storage characteristics.

The epoxy resin composition constituting the sealing resin 60 may further be appropriately blended with various additives such as anti-aluminum etchant such as zirconium hydroxide; inorganic ion exchanger such as cerium oxide hydrate; γ-glycidoxypropyl group; a coupling agent such as trimethoxydecane, 3-aminopropyltrimethoxydecane or epoxy decane; a coloring agent such as carbon black or red iron powder; a low stress component such as polyoxyxene rubber; a natural wax such as carnauba wax, and a synthetic A high-grade fatty acid such as wax or zinc stearate, a metal salt or a release agent such as paraffin; a flame retardant such as aluminum hydroxide, magnesium hydroxide, zinc borate, zinc molybdate or phosphazene, and an antioxidant.

The epoxy resin composition constituting the sealing resin 60 can be melt-kneaded by, for example, mixing the above components at a temperature of 15 ° C to 28 ° C with a stirrer or the like, or further using a kneading machine such as a roll, a kneader or an extruder. After cooling and pulverization, it is necessary to appropriately adjust the degree of dispersion or fluidity.

4 is a plan view showing a first modification of the semiconductor device 100 shown in FIG. 1.

In the present modification, the substrate 20 includes a lead frame on which the wafer holder 24 of the semiconductor wafer 10 and the internal wires are mounted. In this case, the connection terminal 22 provided on the substrate 20 is constituted by, for example, an inner lead. Therefore, the bonding wire 30 will connect the electrode 12 disposed on the semiconductor wafer 10 and the inner wire. The terminals 22 are connected to each other.

In the present embodiment, the substrate 20 is made of, for example, a Cu alloy or a 42 alloy. Further, the surface portion of the connection terminal 22 is made of, for example, Ag or a laminated film in which a Ni layer, a Pd layer, and an Au layer are sequentially laminated. In this case, high joint reliability can be achieved between the bonding wire 30 and the connection terminal 22.

Fig. 5 is a cross-sectional view showing a second modification of the semiconductor device 100 shown in Fig. 1 .

In the present modification, a plurality of semiconductor wafers 10 are laminated on each other on the substrate 20. Between any two of the plurality of semiconductor wafers 10, the semiconductor wafers 10 are electrically connected to each other, for example, by wires 34. That is, the wire 34 is connected to the electrode pad 12 of the semiconductor wafer 10 and the electrode pad 12 of the other semiconductor wafer 10. The wire 34 may have the same configuration as the wire 30, for example.

An alloy layer containing Ag, Al, and Pd is formed at a joint portion between the wire 34 and the electrode pad 12. The alloy layer provided at the joint portion between the wire 34 and the electrode pad 12 has the same configuration as the alloy layer 32 provided at the joint portion between the wire 30 and the electrode pad 12. In this case, it is also possible to realize a joint portion which is excellent in balance between moisture resistance reliability and high-temperature storage characteristics, such as the connection between the lead wires 34 of the two semiconductor wafers 10 which are laminated to each other and the electrode pads 12 connected to the lead wires 34.

In FIG. 5, a case where two semiconductor wafers 10 are laminated on a substrate 20 is exemplified. In addition, the configuration of the semiconductor device 100 of the present modification is not limited to that shown in FIG. 5. In the present modification, for example, an arbitrary number of semiconductor wafers 10 can be laminated on the substrate 20.

Next, an example of a method of manufacturing the semiconductor device 100 of the present embodiment will be described.

First, the semiconductor wafer 10 including the electrode pads 12 is prepared. The semiconductor wafer 10 can be diced by, for example, forming a multilayer wiring layer on a wafer on which an element such as a transistor is formed. Obtained as each semiconductor wafer 10.

Then, the semiconductor wafer 10 is mounted on the substrate 20 having the connection terminals 22. Here, the semiconductor wafer 10 is disposed on a region of the substrate 20 where the connection terminal 22 is not provided. In the present embodiment, the semiconductor wafer 10 is mounted on the substrate 20 via a die attach material provided on the substrate 20, for example.

Then, the electrode pad 12 of the semiconductor wafer 10 and the connection terminal 22 of the substrate 20 are wire-bonded by the wire 30. Thereby, the electrode pad 12 is electrically connected to the connection terminal 22. The above-described wire bonding is carried out in an inert gas atmosphere such as nitrogen, argon or helium, for example, based on the general conditions for wire bonding of an Au wire. Further, as the bonding device, for example, a bonding device for a Cu wire or the like can be used.

Then, the semiconductor wafer 10 and the wires 30 are sealed with an epoxy resin composition. The epoxy resin composition is hardened and formed by, for example, a molding method such as a transfer mold, a compression mold, or an injection mold.

Then, the epoxy resin composition is post-hardened at a temperature of about 80 ° C to 200 ° C for about 10 minutes to 24 hours. Thereby, the sealing resin 60 which consists of hardened material of an epoxy resin composition is formed. The post-hardening is preferably carried out at 150 ° C to 200 ° C for 2 to 16 hours.

According to the present embodiment, the semiconductor device 100 is formed in this manner, for example.

As described above, according to the present embodiment, the bonding portion 40 of the electrode pad 30 made of the first metal material containing the main component of Ag and containing Pd and the electrode pad 12 made of the second metal material having the main component of Al is formed to contain Ag, Alloy layer of Al and Pd. Thereby, the bonding reliability between the wire and the electrode pad can be improved.

[Examples]

Next, an embodiment of the present invention will be described.

(Adjustment of epoxy resin composition)

For each of Production Examples 1 to 3, the epoxy resin composition was adjusted as follows.

First, the components blended according to Table 1 were mixed at 15 to 28 ° C using a stirrer. Then, the obtained mixture was subjected to rolling kneading at 70 to 100 °C. Then, the kneaded mixture was cooled and pulverized to obtain an epoxy resin composition. Further, the details of each component in Table 1 are as follows. Further, the unit in Table 1 is mass%.

(A) Epoxy resin

EP-BA (phenolic aralkyl type epoxy resin with extended biphenyl skeleton): NC3000P, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 276, Cl ion concentration 280ppm

(B) hardener

HD-BA (phenolic aralkyl resin with extended phenyl skeleton): MEH-7851SS, manufactured by Minghe Chemical Co., Ltd., hydroxyl equivalent 203

(C) filling material

Ceria: FB-820, manufactured by the Electrochemical Industry Co., Ltd., with an average particle size of 26.5 μm and particles of 105 μm or more and 1% or less.

(D) Neutralizer

Hydrotalcite: DHT-4A (registered trademark) (in the above formula (5), a is 4.3, b is 2, c is 1 hydrotalcite) manufactured by Kyowa Chemical Industry Co., Ltd.

(E) hardening accelerator

Triphenylphosphine (TPP), manufactured by Beixing Chemical Industry Co., Ltd.

(F) organic sulfur compounds

Compound 1: 3-mercaptopropyltrimethoxydecane

Compound 2: 3-amino-5-mercapto-1,2,4-triazole

(G) Other ingredients

Coupling agent: epoxy decane

Colorant: carbon black

Release agent: carnauba wax

(spiral flow)

The epoxy resin compositions of Production Examples 1 to 3 were subjected to a mold temperature of 175 ° C, an injection pressure of 6.9 MPa, and a hardening time of 120 seconds using a low pressure transfer molding machine ("KTS-15" manufactured by Kohtaki Precision Machine Co., Ltd.). The flow length was measured by injecting into a metal mold for spiral flow measurement based on EMMI-1-66. The unit in Table 1 is cm.

(gel time)

The epoxy resin compositions of Production Examples 1 to 3 were each melted on a hot plate heated to 175 ° C, and then the time until hardening was measured while kneading by a spatula. The unit in Table 1 is seconds.

(Measurement of pH)

The cured product of the epoxy resin compositions of Production Examples 1 to 3 was applied to a mold temperature of 175 ° C, an injection pressure of 7.5 MPa, and a hardening time of 2 using a low pressure transfer molding machine ("KTS-15" manufactured by Kohtaki Precision Machine Co., Ltd.). Forming under minute conditions to obtain 50mm × 3mm test piece. Then, the obtained test piece was post-hardened at 175 ° C for 4 hours, and then finely pulverized to obtain a pulverized product. Then, 50 ml of distilled water was added to 5 g of the pulverized product, placed in a Teflon (registered trademark)-lined container, and treated at 125 ° C for 20 hours to obtain an extract. The pH of the extract was measured using a pH meter.

(Measurement of sulfur content)

About 5 mg of the cured product of the epoxy resin composition of Production Examples 1 to 3 was weighed and burned in a flask filled with oxygen inside. The 5% potassium hydroxide solution was allowed to absorb the combustion gas generated thereby. The amount of sulfate ion in the 5% potassium hydroxide solution measured by ion chromatography is converted into the sulfur content in the epoxy resin composition. The unit in Table 1 is ppm.

(Production of semiconductor device)

For each of Examples 1 to 7 and Comparative Examples 1 and 2, a semiconductor device was produced as follows.

A TEG (Test Element Group) wafer (3.5 mm × 3.5 mm) having an electrode pad made of a metal material having an Al purity of 95.0% (Cu 5.0%) was mounted on a 352-pin BGA (Ball Grid Array, ball) Grid array) (substrate is 0.56mm thick, double maleamide - three A resin/glass fiber cloth substrate having a package size of 30 mm × 30 mm and a thickness of 1.17 mm). Then, using the wires made of the metal materials of Tables 2 and 3, the electrode pads of the TEG wafer (hereinafter referred to as electrode pads) and the connection terminals of the BGA substrate (hereinafter referred to as connection terminals) were wire-bonded at a wire pitch of 80 μm.

The structure obtained by this was used in a low-pressure transfer molding machine ("Y Series" manufactured by TOWA) under the conditions of a mold temperature of 175 ° C, an injection pressure of 6.9 MPa, and a hardening time of 2 minutes, using the production examples according to Tables 2 and 3. The obtained epoxy resin composition was subjected to sealing molding to prepare 352 Pin BGA package. Thereafter, the obtained BGA was packaged and cured at 175 ° C for 4 hours to obtain a semiconductor device.

(TEM analysis)

In each of Examples 1 to 7 and Comparative Examples 1 and 2, the obtained semiconductor device was heated at 175 ° C for 16 hours in the atmosphere, and then the wire and the electrode pad were analyzed using a transmission electron microscope (TEM). The construction of the joint.

In the semiconductor devices of Examples 1 to 7, an alloy layer containing Ag, Al, and Pd was observed at the joint portion between the wire and the electrode pad. On the other hand, in the semiconductor devices of Comparative Examples 1 and 2, an alloy layer containing Ag, Al, and Pd was not observed in the joint portion between the lead wire and the electrode pad.

(moisture resistance reliability)

In the semiconductor devices of Examples 1 to 7 and Comparative Examples 1 and 2, a HAST (Highly Accelerated Stress Test) was performed. HAST was carried out in accordance with IEC68-2-66 under the test conditions of a temperature of 130 ° C, a humidity of 85% RH, an applied voltage of 20 V, and 96 hours. For the semiconductor device after the test, the resistance value between the wire and the electrode pad was measured, and the resistance value which was less than 110% with respect to the initial resistance value was ◎, and the resistance was 110% or more and 120% or less. The value is set to ○, and the resistance value greater than 120% is displayed as ×.

(high temperature storage characteristics)

For the semiconductor devices of Examples 1 to 7 and Comparative Examples 1 and 2, an HTSL (High Temperature Storage Life Test) was performed. The HTSL was carried out under the test conditions of a temperature of 185 ° C for 1,000 hours. For the semiconductor device after the test, the resistance value between the wire and the electrode pad was measured, and the resistance value which was less than 110% with respect to the initial resistance value was ◎, and the resistance was 110% or more and 120% or less. The value set to ○ will show large The resistance value at 120% is set to ×.

(adhesion)

In each of Examples 1 to 7 and Comparative Examples 1 and 2, four semiconductor devices obtained were treated in an environment of 85 ° C and a relative humidity of 85% for 168 hours, and then subjected to IR (infrared radiation) reflow processing ( 260 ° C). Then, the inside of the semiconductor device after the treatment was observed by the ultrasonic flaw detector, and the peeling area of the sealing resin from the semiconductor wafer or the wire was calculated. For all semiconductor devices, the case where the peeling area is less than 5% is ◎, the case where 5% or more and 10% or less is ○, and the case where more than 10% is used is ×.

As described above, in Examples 1 to 7, an alloy layer containing Ag, Al, and Pd was observed at the joint portion between the wire and the electrode pad. In such embodiments 1 to 7, high temperature storage characteristics and resistance Both wet reliability tests and adhesions gave good results. Among them, in Examples 1, 2, 3, and 7, a semiconductor device having particularly excellent adhesion as compared with the other examples was obtained. Further, in Examples 1 to 6, a semiconductor device having particularly excellent high-temperature storage characteristics as compared with Example 7 was obtained. Further, in Examples 1, 2, 4, 5, and 7, a semiconductor device having particularly excellent moisture resistance reliability as compared with the other examples was obtained.

The present application claims the priority of Japanese Patent Application No. 2013-129375, filed on Jun.

10‧‧‧Semiconductor wafer

12‧‧‧electrode pads

20‧‧‧Substrate

22‧‧‧Connecting terminal

30‧‧‧Wire (bonding wire)

30a‧‧‧ front end

40‧‧‧ joints

100‧‧‧Semiconductor device

Claims (5)

A semiconductor device comprising: a semiconductor wafer including an electrode pad; and a wire electrically connected to the electrode pad, wherein the wire is made of a first metal material containing a main component of Ag and containing Pd, wherein the electrode pad is composed of a main component The second metal material of Al is formed, and an alloy layer containing Ag, Al, and Pd is formed on the joint portion between the wire and the electrode pad. The semiconductor device according to claim 1, wherein the first metal material constituting the wire has an Ag content of 85% by weight or more and 99.5% by weight or less. The semiconductor device according to claim 1 or 2, wherein the semiconductor wafer and the lead wire are sealed by a cured product of an epoxy resin composition, and a sulfur content in the cured product of the epoxy resin composition is 1 ppm or more And 400ppm or less. The semiconductor device of claim 3, wherein the cured product of the epoxy resin composition contains an organic sulfur compound. The semiconductor device according to claim 3, wherein the cured product of the epoxy resin composition has a pH of 4 or more and 7 or less.