WO2021065036A1 - Wire joining structure, bonding wire used in same, and semiconductor device - Google Patents

Wire joining structure, bonding wire used in same, and semiconductor device Download PDF

Info

Publication number
WO2021065036A1
WO2021065036A1 PCT/JP2020/010119 JP2020010119W WO2021065036A1 WO 2021065036 A1 WO2021065036 A1 WO 2021065036A1 JP 2020010119 W JP2020010119 W JP 2020010119W WO 2021065036 A1 WO2021065036 A1 WO 2021065036A1
Authority
WO
WIPO (PCT)
Prior art keywords
gold
wire
bonding
silver
electrode
Prior art date
Application number
PCT/JP2020/010119
Other languages
French (fr)
Japanese (ja)
Inventor
優希 安徳
雄祐 ▲崎▼田
将太 川野
▲祐▼佳 平井
Original Assignee
田中電子工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 田中電子工業株式会社 filed Critical 田中電子工業株式会社
Priority to KR1020227008680A priority Critical patent/KR20220047621A/en
Priority to JP2021551112A priority patent/JP7269361B2/en
Priority to DE112020004723.7T priority patent/DE112020004723T5/en
Priority to CN202080064592.7A priority patent/CN114502754B/en
Publication of WO2021065036A1 publication Critical patent/WO2021065036A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
    • H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
    • H01L23/495—Lead-frames or other flat leads
    • H01L23/49517—Additional leads
    • H01L23/4952—Additional leads the additional leads being a bump or a wire
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/42—Wire connectors; Manufacturing methods related thereto
    • H01L24/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • C22C5/06—Alloys based on silver
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
    • H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
    • H01L23/49—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions wire-like arrangements or pins or rods
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/02—Bonding areas ; Manufacturing methods related thereto
    • H01L24/07—Structure, shape, material or disposition of the bonding areas after the connecting process
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/42—Wire connectors; Manufacturing methods related thereto
    • H01L24/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/42—Wire connectors; Manufacturing methods related thereto
    • H01L24/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L24/45—Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/42—Wire connectors; Manufacturing methods related thereto
    • H01L24/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L24/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02—Bonding areas; Manufacturing methods related thereto
    • H01L2224/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/04042—Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02—Bonding areas; Manufacturing methods related thereto
    • H01L2224/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/05—Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H01L2224/0554—External layer
    • H01L2224/05599—Material
    • H01L2224/056—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
    • H01L2224/05617—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof the principal constituent melting at a temperature of greater than or equal to 400°C and less than 950°C
    • H01L2224/05624—Aluminium [Al] as principal constituent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02—Bonding areas; Manufacturing methods related thereto
    • H01L2224/07—Structure, shape, material or disposition of the bonding areas after the connecting process
    • H01L2224/08—Structure, shape, material or disposition of the bonding areas after the connecting process of an individual bonding area
    • H01L2224/081—Disposition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02—Bonding areas; Manufacturing methods related thereto
    • H01L2224/07—Structure, shape, material or disposition of the bonding areas after the connecting process
    • H01L2224/08—Structure, shape, material or disposition of the bonding areas after the connecting process of an individual bonding area
    • H01L2224/085—Material
    • H01L2224/08501—Material at the bonding interface
    • H01L2224/08503—Material at the bonding interface comprising an intermetallic compound
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32135—Disposition the layer connector connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip
    • H01L2224/32145—Disposition the layer connector connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip the bodies being stacked
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L2224/45—Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
    • H01L2224/45001—Core members of the connector
    • H01L2224/45099—Material
    • H01L2224/451—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
    • H01L2224/45138—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof the principal constituent melting at a temperature of greater than or equal to 950°C and less than 1550°C
    • H01L2224/45139—Silver (Ag) as principal constituent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L2224/45—Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
    • H01L2224/4554—Coating
    • H01L2224/45565—Single coating layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L2224/45—Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
    • H01L2224/4554—Coating
    • H01L2224/45599—Material
    • H01L2224/456—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
    • H01L2224/45638—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof the principal constituent melting at a temperature of greater than or equal to 950°C and less than 1550°C
    • H01L2224/45644—Gold (Au) as principal constituent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48095—Kinked
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48135—Connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip
    • H01L2224/48137—Connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip the bodies being arranged next to each other, e.g. on a common substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/48247—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/484—Connecting portions
    • H01L2224/48463—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/484—Connecting portions
    • H01L2224/48463—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
    • H01L2224/48465—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/49—Structure, shape, material or disposition of the wire connectors after the connecting process of a plurality of wire connectors
    • H01L2224/494—Connecting portions
    • H01L2224/4941—Connecting portions the connecting portions being stacked
    • H01L2224/4942—Ball bonds
    • H01L2224/49421—Ball bonds on the semiconductor or solid-state body
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/49—Structure, shape, material or disposition of the wire connectors after the connecting process of a plurality of wire connectors
    • H01L2224/495—Material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73251—Location after the connecting process on different surfaces
    • H01L2224/73265—Layer and wire connectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/02—Bonding areas ; Manufacturing methods related thereto
    • H01L24/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L24/05—Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L24/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L24/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/73—Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/102—Material of the semiconductor or solid state bodies
    • H01L2924/1025—Semiconducting materials
    • H01L2924/10251—Elemental semiconductors, i.e. Group IV
    • H01L2924/10253—Silicon [Si]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/15—Details of package parts other than the semiconductor or other solid state devices to be connected
    • H01L2924/181—Encapsulation

Definitions

  • the present invention relates to a wire bonding structure and a bonding wire and a semiconductor device used therein.
  • the electrodes of the semiconductor chip and the external electrodes of the circuit base material such as the lead frame and the circuit board are connected by, for example, a bonding wire.
  • a bonding wire for example, one end of the bonding wire is bonded to the electrode of the semiconductor chip (first bonding) by a method called ball bonding, and the other end of the bonding wire is bonded to the external electrode of the circuit substrate by a method called wedge bonding (first bonding).
  • Second bonding is common.
  • ball bonding one end of the bonding wire is melted by discharge or the like and solidified into a spherical shape by surface tension or the like to form a ball.
  • the solidified ball is called a free air ball (FREE Air Ball: FAB), and is connected to an electrode of a semiconductor chip by a thermocompression bonding method or the like combined with ultrasonic waves to form a wire bonding structure.
  • FAB free air ball
  • the structure in which the FAB provided on the bonding wire is bonded to the electrode is referred to as a wire bonding structure here.
  • the semiconductor device is configured by resin-sealing the semiconductor chip to which the bonding wire is connected together with the bonding wire and a part of the circuit base material.
  • semiconductor devices have been required to have low power consumption and high signal processing speed, and bonding wires used in such semiconductor devices have low electrical resistance (specific resistance) (for example, purity 99.99). It is required to have a mass% of 4NAu wire or less) and to maintain a low specific resistance for a long time even in a harsh environment, that is, to have high reliability. High reliability means that it is not corroded (sulfurized or oxidized) even in a hot and humid environment, and its electrical resistance does not increase for a long period of time.
  • the gold wire generally used conventionally has a high material cost, and the copper wire and the coated copper wire have a problem that the material is hard and damages the semiconductor chip.
  • silver wire is suitable as a bonding wire because of its low cost and softness
  • sterling silver wire has a problem that its surface is sulfurized when left in the atmosphere for a long period of time. Since the silver alloy bonding wire commercialized as a measure against sulfurization contains metal elements such as palladium and gold to pure silver, the silver content is 90% by mass to 97% by mass. Although the measures against sulfurization have been slightly improved, the silver alloy bonding wire has a drawback that the specific resistance becomes high due to the influence of the content of additive elements, and does not sufficiently meet the demands of recent semiconductor devices.
  • a silver alloy wire that reduces the content of precious metals and has a specific resistance equivalent to that of gold wire has been proposed, but this time there is a problem of corrosion resistance, so the molded resin that constitutes the semiconductor device, that is, high reliability It is difficult to meet the high reliability evaluation criteria because it is necessary to select a resin that does not contain elements that affect the bonding wire and the intermetallic compound generated at the interface between the bonding wire and the electrode. There is also.
  • a coating layer such as platinum group element such as palladium or gold having high corrosion resistance on the surface of the silver wire.
  • a coating layer such as a platinum group element or gold can suppress sulfide on the surface of silver wire if it remains as a solid that does not melt. Therefore, it is effective when bonding without melting as in wedge bonding (second bonding).
  • first joining As described above, the bonding wire is formed by melting one end of the wire by electric discharge or the like and solidifying it into a spherical shape by surface tension or the like to form a ball.
  • the solidified ball is called a free air ball (FAB), and the FAB is connected to the electrodes of the semiconductor chip by a thermocompression bonding method or the like combined with ultrasonic waves to form a wire bonding structure.
  • Wedge joining without forming balls reduces the joining area and weakens the joining strength. Therefore, a method of increasing the joining force by making the joining area into a ball shape and widening the joining area is generally used. Since the entire wire coated with platinum group element or gold is melted during FAB formation, the coated platinum group element or gold is also melted almost at the same time, although there is a time lag due to the difference in melting point, etc. Gold enters and the concentration of platinum group elements and gold on the ball surface becomes relatively low.
  • Patent Document 1 describes a gold-silver alloy wire containing Ag in the range of 11 to 18.5% by mass and the balance being gold and unavoidable impurities, and Cu, Pd, and Pt. At least one kind is 0.01 to 4% by mass in total, at least one kind of Ca, In and rare earth elements is 0.0005 to 0.05% by mass in total, or at least one kind of Mn and Cr is 0. A gold-silver alloy wire contained in the range of 01 to 0.2% by mass is disclosed. Patent Document 1 provides a gold-silver alloy wire in which a specific amount of silver is contained to improve the bonding reliability of silver with an aluminum electrode and to reduce the cost. However, since the main component is still gold, the problem of high material cost is not solved because it is more expensive than silver wire, silver alloy wire, coated silver wire and the like. In addition to cost issues, there is also concern that resistivity will increase.
  • Patent Document 2 describes that one or more of Pd, Au, Zn, Pt, Ni, Sn or one or more of Pd, Au, Zn, Pt, Ni, Sn on the surface of Ag or Ag alloy wire.
  • a bonding wire having a wire coating layer having an alloy or an oxide or nitride of these metals is disclosed.
  • Patent Document 2 uses an Ag or Ag alloy wire having a coating layer for connection in a power semiconductor device, and by using wedge bonding instead of ball bonding, an intermetallic compound at the bonding interface between the Al electrode and Ag wire. It is disclosed that the formation of the metal is suppressed and the joint reliability is enhanced.
  • Patent Document 2 presupposes wedge bonding of Ag wires as described above, it does not form FAB in which the coated wires must be melt-solidified. Therefore, the constituent elements of the coating layer are contained in the Ag wires as the core material. Not considering getting in. Therefore, Patent Document 2 does not consider the constituent elements of the bonding interface when the FAB is bonded to the electrode, and does not consider improving the reliability based on the constituent elements of the bonding interface. Furthermore, the configuration for suppressing the entry of the constituent elements into the Ag wire is not disclosed.
  • Patent Document 3 has an Ag wire and an Au film covering the Ag wire, and the Au film is Na, Se, Ca, Si, Ni, Be, K, C. , Al, Ti, Rb, Cs, Mg, Sr, Ba, La, Y, Ce.
  • the shape of the FAB is not axisymmetric with the Au-coated Ag wire, the above-mentioned element is contained in the Au film to suppress the concentration of the arc discharge at one point, and an arc is generated from the entire surface. It is disclosed that the shape of the FAB is stabilized by allowing the FAB to be formed.
  • Patent Document 3 also does not consider that Au of the coating layer enters the Ag line during FAB formation, and does not disclose a configuration for suppressing the entry of Au into the Ag line. Therefore, Patent Document 3 not only does not suggest that an intermetal compound is formed at the bonding interface between the Al electrode and the Ag wire when the gold-coated silver wire is used, and the bonding reliability is lowered, and further, Al The configuration for enhancing the bonding reliability between the electrode and the Ag wire is also not disclosed. Further, the above-mentioned additive elements may adversely affect the characteristics of the wire itself, the formability of the coating layer, and the like depending on the content thereof. Therefore, there is a demand for a technique for suppressing the entry of Au into the Ag wire and improving the reliability of the wire bonding structure without adversely affecting the characteristics of the wire itself and the formability of the coating layer.
  • the problem to be solved by the present invention is that the bonding wire and the aluminum electrode can be bonded for a long period of time even in a harsh environment while suppressing an increase in the specific resistance even when the bonding wire and the aluminum electrode are bonded at a low material cost. It is an object of the present invention to provide a wire bonding structure capable of maintaining bonding reliability, and a bonding wire and a semiconductor device used for the wire bonding structure.
  • the wire bonding structure of the present invention includes an electrode containing aluminum as a main component, a bonding wire, and a ball compression portion provided at one end of the bonding wire and bonded to the electrode.
  • the bonding wire has a core material containing silver as a main component and a coating layer provided on the surface of the core material and containing gold as a main component, and has sulfur, tellurium, and selenium.
  • a gold-coated silver bonding wire containing at least one Group 15 and 16 element selected from, arsenic, and antimony, having a gold concentration of 2.0% by mass or more and 7.0% by mass or less with respect to the entire wire.
  • the total concentration of the 15th and 16th group elements is 4% by mass or more and 80% by mass or less, and the concentration of gold is the total amount of gold, silver and aluminum in the vicinity of the junction interface between the electrode and the ball compression portion.
  • the problem is solved by providing a gold-enriched bonding region of 5 atomic% or more.
  • the gold-coated silver bonding wire of the present invention is a gold-coated bonding wire used in the wire connection structure of the present invention, and the gold-coated bonding wire is formed on a core material containing silver as a main component and a surface of the core material.
  • the gold-coated silver bonding wire is provided and has a coating layer containing gold as a main component, and the gold-coated silver bonding wire contains at least one Group 15 and 16 element selected from sulfur, tellurium, selenium, arsenic, and antimony.
  • the concentration of gold is 2.0% by mass or more and 7.0% by mass or less, and the concentrations of Group 15 and 16 elements are 4% by mass or more and 80% by mass or less with respect to the entire wire.
  • gold is placed in the vicinity of the bonding interface between the electrode and the ball compression portion.
  • the semiconductor device of the present invention comprises one or more semiconductor chips having at least one electrode, a lead frame or a substrate, between the electrodes of the semiconductor chip and the lead frame, the electrodes of the semiconductor chip and the substrate. At least one selected from between the electrodes and between the electrodes of the plurality of semiconductor chips is provided with a core material containing silver as a main component and a coating layer provided on the surface of the core material and containing gold as a main component.
  • the semiconductor device is connected by a bonding wire, and the connection structure between the electrode and the bonding wire includes a ball compression portion provided to bond one end of the bonding wire to the electrode, and is provided with the electrode.
  • a gold-concentrated bonding region having a gold concentration of 5 atomic% or more with respect to the total amount of gold, silver, and aluminum is provided in the vicinity of the bonding interface with the ball compression portion.
  • the concentration of gold in the vicinity of the bonding interface between the electrode and the ball compression portion is gold, silver, and aluminum while suppressing an increase in the specific resistance of the bonding wire.
  • a gold-concentrated bonding region of 5 atomic% or more can be provided with respect to the total amount.
  • FIG. 1 is a cross-sectional view showing a wire bonding structure of an embodiment.
  • the wire bonding structure 1 of the embodiment includes an electrode 2 containing aluminum (Al) as a main component, and a bonding wire 3 having one end bonded to the electrode 2.
  • the bonding wire 3 has a core material (also referred to as a silver core material) 4 containing silver (Ag) as a main component, and a coating layer 5 provided on the surface of the core material 4 and containing gold (Au) as a main component. It is a gold-coated silver bonding wire.
  • Electrode 2 contains aluminum as a main component.
  • Examples of the configuration of the electrode 2 include, but are not limited to, an electrode provided on the semiconductor chip.
  • the electrode 2 may be made of pure aluminum, or may be made of an aluminum alloy in which an additive element is added to aluminum.
  • the electrode 2 contains aluminum as a main component so as not to impair the function as the aluminum electrode 2.
  • the electrode 2 is composed of Al-0.5% copper (Cu) and Al-1.0% silicon (Si) -copper (Cu), but is not limited thereto.
  • the wire bonding structure 1 of the embodiment includes a ball compression unit 6 provided so as to bond one end of the gold-coated silver bonding wire 3 to the electrode 2.
  • the ball compression unit 6 bonds the wire through a penetrating jig called a capillary when the ball is bonded, but when the wire is pressed against the electrode to be bonded, the ball is deformed into the shape inside the capillary. The part that is processed and shaped.
  • the FAB formed by melting one end of the bonding wire 3 by discharge or the like and solidifying it into a spherical shape by surface tension or the like is formed by pressing the FAB against the electrode 2 by a thermocompression bonding method using ultrasonic waves or the like to bond the bonding wire 3.
  • a gold-enriched bonding region 7 having a gold concentration of 5 atomic% or more with respect to the total amount of gold, silver, and aluminum is provided in the vicinity of the bonding interface between the electrode 2 and the ball compression unit 6.
  • the gold concentration in the vicinity of the bonding interface is increased and the silver concentration is relatively increased. It can be kept low. Therefore, it is possible to improve the joint reliability between the electrode 2 and the ball compression unit 6. That is, when the ball compression portion 6 is formed using a silver alloy bonding wire having a silver purity of 98% by mass or more (hereinafter referred to as a high-purity silver alloy wire), the silver concentration in the vicinity of the bonding interface becomes high and is easily corroded.
  • An intermetallic compound of silver and aluminum (such as Ag 3 Al having a ratio of silver and aluminum of 3: 1) is likely to be formed.
  • the high-purity silver-alloy wire precious metals such as gold and palladium contained 2 wt% at the maximum, since the intermetallic compound of the corrosion resistance of low silver and aluminum, such as Ag 3 Al is produced, the molding resin The metal-metal compound is corroded by the halogen such as chlorine (Cl) contained in the metal and the moisture absorbed by the mold resin, and a poor energization is likely to occur between the electrode 2 and the ball compression unit 6.
  • the Ag 3 Al intermetallic compound is suppressed, so that the ratio of silver to aluminum is 2: 1.
  • Ag 2 Al intermetallic compound is likely to be produced. Since the Ag 2 Al intermetallic compound is superior in corrosion resistance to the Ag 3 Al intermetallic compound, the bonding reliability between the electrode 2 and the ball compression portion 6 can be improved.
  • the gold present in the gold-enriched bonding region 7 acts as a barrier against changes over time in a harsh environment, such as silver migration and diffusion, and provides a corrosion-resistant Ag 2 Al intermetallic compound. Can be maintained.
  • gold produces aluminum and an intermetallic compound of gold and aluminum having better corrosion resistance (for example, an Au 4 Al intermetallic compound), which contributes to further improvement of bonding reliability.
  • an Au 4 Al intermetallic compound for example, an Au 4 Al intermetallic compound
  • the gold concentration is 5 atomic% or more with respect to the total amount of gold, silver, and aluminum. If the concentration of gold in the gold-enriched bonding region 7 is less than 5 atomic% with respect to the total amount of gold, silver and aluminum, the effect of suppressing corrosion (sulfurization and oxidation) by gold cannot be sufficiently obtained. Since the silver concentration is relatively increased, the Ag 3 Al metal-metal compound is likely to be formed, and the bonding reliability between the electrode 2 and the ball compression portion 6 is lowered.
  • the gold concentration in the gold-enriched bonding region 7 with respect to the total amount of gold, silver and aluminum is more preferably 5 atomic% or more, and further preferably 10 atomic% or more. It is determined by the ratio of the thickness of the coating layer 5 to the diameter of the silver core material 4.
  • the gold-concentrated bonding region 7 described above further comprises at least one element selected from palladium (Pd), platinum (Pt), germanium (Ge), indium (In), copper (Cu), and nickel (Ni) (hereinafter,).
  • M element is preferably contained.
  • the M element can be contained in, for example, the silver core material 4.
  • the M element is preferably contained so that its content is 0.2 atomic% or more and 2.0 atomic% or less with respect to the entire wire. If it is less than 0.2 atomic%, the effect of further improving the bonding reliability by the M element cannot be sufficiently obtained, and if it exceeds 2.0 atomic%, the specific resistance of the silver core material 4 may be increased. is there.
  • the analysis method of the gold-enriched bonding region will be described in detail by taking as an example the case where an aluminum electrode is used as the bonding target. The same applies when an electrode containing aluminum and an element other than aluminum is used.
  • Free air balls are formed using gold-coated silver bonding wires and ball-bonded onto aluminum electrodes.
  • the ball compression portion joined to the aluminum electrode is cut so that the surface parallel to the center line in the longitudinal direction of the wire is exposed.
  • This cut surface is line-analyzed from a predetermined position on the wire side in a direction substantially perpendicular to the joint surface (depth direction).
  • FE-SEM / EDX field emission scanning electron microscope / energy dispersive X-ray spectroscopic analysis
  • the cut surface according to the analysis includes the center line in the longitudinal direction of the wire or is formed so as to be as close to the center line as possible.
  • the cut surface of the ball joint can be made as follows.
  • a PBGA32PIN frame is used as the lead frame, and a substantially square semiconductor chip is bonded to the central portion of the frame.
  • the aluminum electrode on the semiconductor chip and the external electrode on the frame are wire-bonded with a gold-coated silver bonding wire to prepare a measurement sample.
  • a gold-coated silver bonding wire is ball-bonded (first bonding) to an aluminum electrode on the semiconductor chip, and wedge-bonded (second bonding) to a lead frame. Since many electrodes are usually arranged in multiple rows on a chip, for example, bonding wires are bonded to one row (4) of electrodes at equal intervals, and the other 3 rows (3 sides) are similarly bonded. Join.
  • a total of 16 aluminum electrodes are ball-bonded. Including wedge bonding to the lead frame, there are a total of 32 sets of wire bonding.
  • the conditions for forming the free air ball are, for example, when the wire diameter of the gold-coated silver bonding wire is 10 to 30 ⁇ m, the discharge current value is 30 to 90 mA, and the free air ball diameter is 1.5 to 2.
  • the bonder device for example, a commercially available product such as a bonder device (fully automatic bonder: IConn ProCu PLUS) manufactured by K & S Co., Ltd. can be used.
  • the bonder device settings are that the discharge time is 50 to 1000 ⁇ s, the EFO-Gap is 25 to 45 mil (about 635 to 1143 ⁇ m), and the tail length is 6 to 12 mil (about 152 to 305 ⁇ m). preferable.
  • the conditions may be the same as above, for example, the free air ball diameter may be the same as the above.
  • the ball joining condition is, for example, for a free air ball having a wire wire diameter of 20 ⁇ m and a ball diameter of 36 ⁇ m, the height from the constricted portion of the ball compression portion to the junction interface side. Can be adjusted by a bonder device so that the maximum width in the direction substantially parallel to the joint surface is approximately 45 ⁇ m, and the ball share strength is approximately 15 gf or more.
  • the conditions for the second joining are, for example, a crimping force of 60 gf, an ultrasonic output of 90 mAmps, and an ultrasonic output time of 15 ms.
  • the loop length from the first joint to the second joint can be set to 2.0 mm.
  • the semiconductor chip containing a total of 16 sets of joints formed above is molded with a sealing resin by a molding machine.
  • the mold has hardened, the molded part is cut from the frame, and further, the vicinity of one row (one side) of the ball joint in the mold part is cut.
  • the cut mold is placed in a cylindrical mold in a direction in which the cross section of the ball joint can be polished, and the embedded resin is poured and a curing agent is added to cure the cut mold.
  • the cured cylindrical resin containing the semiconductor chip is roughly polished with a polishing machine so that the vicinity of the center of the ball joint is exposed as much as possible.
  • the final polishing finish and the surface including the center of the ball (the surface that passes through the center line of the wire and is parallel to the center line) is just exposed and is at the position of the analysis surface.
  • the desired portion is line-analyzed from the ball side to the electrode side by FE-SEM / EDX.
  • the line analysis conditions are, for example, an acceleration voltage of 6 keV, a measurement area of ⁇ 0.18 ⁇ m, and a measurement interval of 0.02 ⁇ m.
  • field emission is performed from the ball compression portion 6 side toward the electrode 2 side via the bonding interface on the analysis surface (polished cross section) of the measurement sample described above.
  • the gold-enriched junction region 7 can be confirmed by line analysis by energy dispersive X-ray analysis (EDX: Energy Dispersive X-ray Samplery) attached to a type scanning electron microscope (FE-SEM: Field Emission-Scanning Electron Microscope).
  • the line analysis conditions are an acceleration voltage of 6 keV, a measurement length of 2 ⁇ m, a measurement interval of 0.03 ⁇ m, and a measurement time of 60 seconds using FE-SEM SU8220 manufactured by Hitachi High-Technologies Corporation and XFlash (R) 5060FQ manufactured by Bruker Corporation. ..
  • concentration profile of the line analysis if the gold concentration is 5 atomic% or more with respect to the total amount of silver, gold and aluminum, it can be determined that the gold-enriched bonding region 7 is formed.
  • the ratio of gold to the total of gold, silver, and aluminum is in the vicinity of the bonding surface where the free air ball and the electrode are contacted and bonded, that is, in the region where aluminum, silver, and gold coexist. It can be evaluated as a predetermined range of 5.0 atomic% or more, preferably 10.0 atomic% or more.
  • the ratio of gold to the total of gold, silver, and aluminum is 5.0 atomic% or more, preferably 10.0 atoms.
  • a predetermined range of% or more can be evaluated as a gold-enriched bonding region.
  • the reason why the aluminum concentration is measured in the range of more than 5.0 atomic% and 95.0 atomic% or less is that the analytical value of the place where aluminum does not exist does not become 0 atomic% due to the influence of noise in the analysis. This is because the analytical value of the aluminum-only portion may not be 100 atomic%.
  • FIG. 2 shows an example of the line analysis result by EDX.
  • the vertical axis represents the concentration (atomic%) of each element
  • the horizontal axis represents the measurement distance ( ⁇ m) in the measurement sample.
  • the region from the measurement distance of about 2.2 ⁇ m to about 2.6 ⁇ m on the horizontal axis of FIG. 2 is the region near the bonding interface, and the region where the gold concentration is 5.0 atomic% or more, that is, gold There is a junction thickening region.
  • the peak concentration of gold shows about 15.0 atomic%. Therefore, in the wire bonding structure 1 having the concentration profile shown in FIG. 2, it can be determined that the gold-concentrated bonding region 7 exists in the vicinity of the bonding interface between the electrode 2 and the ball compression unit 6.
  • FIG. 2 there is a region where the gold concentration is low (around 2.4 ⁇ m on the horizontal axis) near the bonding interface, but an Ag 2 Al intermetallic compound having strong corrosion resistance is generated from the concentration ratio of silver and aluminum in the vicinity. It is presumed.
  • the formation range of the gold-enriched bonding region 7 described above is preferably, but not limited to, the entire area of the bonding interface between the electrode 2 and the ball compression portion 6. That is, as shown in FIG. 3, the gold-enriched bonding region 7 has a gold-enriched bonding region with respect to the maximum width Y of the ball compression unit 6 in order to improve the bonding reliability between the electrode 2 and the ball compression unit 6. 7 may be formed at least between both outer peripheral portions of the ball compression portion 6 and the position of 1/8 (indicated by the line X1 and the line X2).
  • the maximum width Y of the ball compression portion 6 is a cross-sectional view obtained by cutting the joint structure between the electrode 2 and the ball compression portion 6 shown in FIG.
  • the width between both outermost ends (indicated by the line X) of the ball compression portion 6 is shown.
  • the maximum width (line Y) of the ball compression portion 6 is divided into eight equal parts from both outermost ends (line X), and the position is 1/8 from both outermost ends (line X1 and line X2). It suffices that at least the gold-enriched bonding region 7 is formed in the meantime. By forming the gold-enriched bonding region 7 at such a position, it is possible to suppress a decrease in bonding reliability between the electrode 2 and the ball compression portion 6 due to air, moisture, or the like entering the bonding interface.
  • the formation range of the gold-enriched joint region 7 is formed so that the total occupancy rate is 25% or more with respect to the maximum width Y of the ball compression portion 6 described above. It turned out that it is preferable.
  • the occupancy rate of the gold-enriched joint region 7 referred to here is the occupancy rate of the gold-enriched joint region 7 when the formation region of the gold-enriched joint region 7 is analyzed in the cross-sectional view of the joint structure between the electrode 2 and the ball compression portion 6 shown in FIG. This means that the formation region of the gold-concentrated joint region 7 is 25% or more with respect to the maximum width Y of the ball compression portion 6.
  • the electrode 2 is formed by air, moisture, or the like invading the bonding interface. It is possible to suppress a decrease in bonding reliability with the ball compression unit 6.
  • the occupancy rate of the gold-enriched bonding region 7 with respect to the maximum width Y of the ball compression unit 6 may be at least 25%, more preferably 40% or more, and further preferably 50% or more. ..
  • the abundance of an element to be measured is usually measured as the X-ray intensity emitted from the element when the measurement target is irradiated with an electron beam, and the intensity is measured on an EPMA image. It is common to display with color mapping reflected in the color. That is, the points where the element to be measured does not exist are displayed in black, and are displayed in gradations such as "white, red, yellow, green, blue, and black" as an example in descending order of the existence probability of the elements.
  • the point with the lowest gold intensity that is, the darkest point (blue part close to black) among the places on the EPMA image where the strength due to gold is observed although it is not black.
  • the gold concentration is 5.0 atomic% or more
  • the region displayed in a color stronger than the above-mentioned portion displayed other than the above can be specified as the gold-enriched junction region.
  • the gold concentration observed in the line analysis was 5.0 atomic% or more, and the intensity was equal to or higher than the measurement point on the EPMA. Whether the location is set so that it can be identified as an intensity difference (color on the image) is visually determined.
  • the core material (silver core material) 4 containing silver as a main component mainly constitutes the bonding wire 3 and bears the function of the bonding wire 3.
  • a core material 4 is preferably made of sterling silver, but in some cases, it may be made of a silver alloy in which an additive element is added to silver.
  • the core material 4 contains silver as a main component so as not to impair the function as a silver bonding wire.
  • the fact that silver is contained as a main component means that the core material 4 contains at least 50% by mass or more of silver.
  • the core material 4 is composed of a silver alloy
  • a silver alloy containing at least one element selected from rhodium (Rh), germanium (Ge), gallium (Ga) and indium (In) is preferably applied, but is not limited thereto.
  • the additive element in the silver alloy constituting the core material 4 is effective in improving the bondability with the electrode, the bond reliability, the mechanical strength, and the like. However, if the content of the additive element is too large, the specific resistance of the core material 4 may increase and the function as a silver bonding wire may deteriorate. Therefore, the content of the additive element of the gold-coated silver bonding wire 3 is set so as to be within the specific resistance of the gold wire (purity 99.99% by mass (4N)), for example, 2.3 ⁇ ⁇ cm or less. Is preferable.
  • the core material 4 When the core material 4 is made of either sterling silver or a silver alloy, it may contain unavoidable impurities, but the amount of impurities in which the specific resistance of the gold-coated silver bonding wire 3 is in the range of 2.3 ⁇ ⁇ cm or less. Is preferable. By applying such a silver core material 4, the value of specific resistance required for the bonding wire 3 can be satisfied. It is often thought that a silver alloy containing more silver, which has a lower resistivity than gold, has a lower resistivity, but a silver alloy has a higher resistivity due to alloying than pure gold (4N). There are many.
  • the specific resistance of the wire is preferably measured by the four-terminal method, and is measured using, for example, a milliohm meter (Yokogawa Hewlett-Packard Co., Ltd., model number 4328A) or the like.
  • the coating layer 5 contains gold as a main component.
  • the inclusion of gold as a main component means that the coating layer 5 contains 50% by mass or more of gold.
  • the gold content of the coating layer 5 can be measured from the surface of the bonding wire 3 by quantitative analysis of the outermost surface of the wire by Auger electron spectroscopy (AES) or the like.
  • AES Auger electron spectroscopy
  • the gold content referred to here is a value with respect to the total amount of detected metal elements, and does not include carbon, oxygen, etc. existing on the surface due to adsorption or the like.
  • the gold-coated silver bonding wire 3 described above preferably has a wire diameter of 13 ⁇ m or more and 30 ⁇ m or less. If the wire diameter of the wire 3 is less than 13 ⁇ m, when wire bonding is performed using the bonding wire 3 at the time of manufacturing a semiconductor device, the strength, conductivity, etc. may decrease, and the reliability of wire bonding may decrease. There is. If the wire diameter of the wire 3 exceeds 30 ⁇ m, the number of bonding wires cannot be increased and the possibility of contact (short circuit) with the adjacent bonding wire increases.
  • the thickness of the coating layer 5 is preferably 50 nm or more and 260 nm or less depending on the wire diameter.
  • the thickness of the coating layer 5 indicates the thickness in the depth direction from the surface of the wire 3 in the region containing gold as a main component toward the core material 4 in the vertical direction. If the thickness of the coating layer 5 is less than 50 nm, the bonding reliability between the gold-coated silver bonding wire 3 and the electrode 2 may not be sufficiently enhanced by the coating layer 5 containing gold as a main component. If the thickness of the coating layer 5 exceeds 260 nm, the formability of the coating layer 5 may decrease.
  • the thickness of the coating layer 5 is preferably set according to the wire diameter of the gold-coated silver bonding wire 3.
  • the thickness of the coating layer 5 shall be measured as follows. That is, in the gold-coated silver bonding wire 3, the element concentration analysis is performed from the surface of the gold-coated silver bonding wire 3 in the depth direction by AES, and the position is 50% when the maximum value of the gold content existing near the surface is set to 100%. The portion to be formed is defined as a boundary portion, and the region from the boundary portion to the surface is determined as the thickness of the coating layer 5.
  • the element distribution in the depth direction from the surface of the gold-coated silver bonding wire 3 can be measured by AES analysis. For example, concentration measurement by AES analysis is effective as a means for analyzing the concentration of each element of the coating layer 5 from the surface of the wire 1 toward the silver core material 4.
  • an Auger electron spectrometer (trade name: JAMP-9500F) manufactured by JEOL Ltd. is used, the acceleration voltage of the primary electron beam is set to 10 kV, the irradiation current is set to 50 nA, and the beam diameter is set to about 4 ⁇ m ⁇ , and the Ar ion sputtering rate is set to SiO2.
  • the conversion value was about 3.0 nm / min.
  • the method of forming the gold-enriched bonding region 7 in the vicinity of the bonding interface between the electrode 2 and the ball compression portion 6 is not particularly limited.
  • a gold-enriched region for example, when forming the FAB at one end of the gold-coated silver bonding wire 3, a gold-enriched region (surface gold-enriched region) is formed on the surface of the FAB. Can be achieved by.
  • the concentration of gold in the vicinity of the junction interface between the electrode 2 and the ball compression portion 6 is gold, silver, and aluminum.
  • a gold-enriched bonding region 7 of 5 atomic% or more with respect to the total amount can be formed. The detailed forming method will be described later.
  • a method of controlling and forming the bonding wire will be described. That is, a method of joining the FAB having the gold-enriched region formed on the surface to the electrode 2 to form the ball compression portion 6 will be described.
  • a FAB 8 is formed at one end of the gold-coated silver bonding wire 3.
  • the conditions for forming the FAB8 for example, when the wire diameter of the gold-coated silver bonding wire 3 is 13 ⁇ m or more and 30 ⁇ m or less, the discharge current value is 30 mA or more and 120 mA or less according to the wire diameter, and the diameter of the FAB8 is 1 of the wire diameter. .
  • the bonder device for example, a commercially available product such as a bonder device (fully automatic bonder: IConn PLUS) manufactured by Curic and Sopha can be used.
  • the device settings include a discharge time of 50 ⁇ s or more and 1000 ⁇ s or less, an EFO-Gap of 20 mil or more and 40 mil or less (about 635 ⁇ m or more and 1143 ⁇ m or less), and a tail length of 6 mil or more and 12 mil or less (about 152 ⁇ m or more and 305 ⁇ m or less). ) Is preferably applied.
  • the conditions may be the same as those of the bonder device, for example, the condition that the diameter of the FAB 8 is the same as that of the bonder device.
  • the gold coating layer 5 coated on the surface of the silver bonding wire is melt-solidified to produce FAB, the gold on the surface enters the inside of the ball, and as a result, the gold concentration on the ball surface decreases, and the silver concentration is relatively high.
  • the inventors have formed a ball in the same manner as a solid wire. Gold is also fixed on the surface of the ball to reduce the silver concentration relatively, and when bonded to an aluminum electrode, the formation of an Ag 2 Al metal-metal compound that is resistant to corrosion, and is extremely stable against chemical reactions.
  • the gold-enriched bonding region 7 cannot be formed with good reproducibility in the vicinity of the bonding interface between the electrode 2 and the ball compression portion 6.
  • the thickness of the gold layer is simply increased, the ratio of the thickness of the gold layer is small when compared with the diameter of the silver core material, so that it is not possible to prevent gold from entering the silver core material.
  • the gold concentration on the surface after the formation of the FAB is increased based only on the thickness of the gold layer, the state becomes closer to the gold wire rather than the gold-coated silver wire, and the material cost increases significantly.
  • the thickness of the gold layer exceeds 7% by mass in terms of the gold concentration in the entire wire, the ball forming property of FAB, that is, the possibility of eccentricity of the ball increases.
  • the inventors have clarified a solution for suppressing the entry of gold into the silver core material 4 at the time of forming the FAB8.
  • Suppression of gold entering the silver core material 4 is performed by sulfur (S), selenium (Se), tellurium (Te), arsenic (As), and antimony (Sb) in the gold constituting the coating layer 5. It has been found that it is obtained by containing at least one selected Group 15 and 16 elements. Further, it has been found that the total amount of the 15th and 16th group elements is preferably 4% by mass or more and 80% by mass or less with respect to the entire wire.
  • the 15th and 16th elements in the coating layer 5 are melted in the process of forming the FAB8. It is presumed that it acts on the surface tension of the coating layer 5 in the state and contributes to the formation of the gold-enriched region.
  • the surface tension of molten silver is smaller than the surface tension of molten gold, and the flow (marangoni convection) generated by the difference in surface tension is from the smaller surface tension to the larger surface tension, that is, melting.
  • the molten gold moves inside the ball.
  • the surface tension of the molten coating layer 5 is smaller than that of molten silver, and the direction of malangoni convection is reversed from the molten gold to the molten silver. , The molten gold does not get inside the FAB8. Therefore, it was speculated that the surface gold-enriched region 9 could be formed on the surface of FAB8.
  • the timing at which the effects of the 15th and 16th elements in the coating layer 5 described above are exhibited and the process of forming the surface gold-enriched region will be described along with the process of forming the FAB8.
  • a wire having a predetermined length is unwound to generate an arc discharge between the tip of the cut bonding wire 3 and the discharge torch, and the wire. It is formed by melting the tip. Since the bonding wire 3 is deformed by being crushed by the capillary at the time of the second bonding, the coating layer 5 does not exist in the region where the bonding wire 3 and the capillary come into contact with each other, and the core material 4 is exposed.
  • the ball in which only the tip of the wire with the core material 4 exposed is melted has a portion where the coating layer 5 does not exist, so that the gold-concentrated region is not formed.
  • the 15th and 16th elements in the coating layer 5 act on the surface tension at the time of melting and melt.
  • Gold is present in the surface region of the FAB8 without getting inside the FAB8. Eventually, it grows from a small ball to a large ball, but gold is continuously supplied from the bonding wire 3. The molten gold is alloyed with the core material 4 melted by the heat of the arc discharge.
  • gold is preferably contained in the range of 2% by mass or more and 7% by mass or less with respect to the total amount of the wire 3.
  • the gold content with respect to the total amount of the wire 3 is less than 2% by mass, the ball compression portion 6 and the electrode 2 formed by using the FAB 8 formed on the gold-coated silver bonding wire 3 mainly composed of the silver core material 4
  • the joint reliability between the wire and the wire cannot be sufficiently improved.
  • the gold content with respect to the total amount of the wire 3 exceeds 7% by mass, the shape of the ball at the time of melting, and eventually the shape of the FAB8, deteriorates due to eccentricity or the like, and the shape and reliability of the ball compression portion 6 are impaired.
  • the material cost of the gold-coated silver bonding wire 3 increases. Although it depends on the diameter of the wire 3 and the thickness of the coating layer 5, the gold content with respect to the total amount of the wire 3 is more preferably 3.5% by mass or more.
  • the Group 15 and Group 16 elements are contained in the range of 4 mass ppm or more and 80 mass ppm or less with respect to the total amount of the gold-coated silver bonding wire 3 described above. Is preferable.
  • the content of the 15th and 16th elements with respect to the total amount of the wire 3 is less than 4% by mass, the gold enrichment effect at the time of forming the FAB8 and the resulting formability of the surface gold enrichment region can be sufficiently obtained. I can't.
  • the content of the 15th and 16th group elements with respect to the total amount of the wire 3 exceeds 80% by mass ppm, cracks and cracks are likely to occur in the coating layer 5, and the workability and productivity such as disconnection during wire drawing are lowered. However, it becomes difficult to obtain the gold-coated silver bonding wire 3 having a desired wire diameter. Two or more kinds of Group 15 and Group 16 elements may be mixed and applied, and in that case, the total amount of the Group 15 and Group 16 elements is adjusted to be within the above-mentioned content range.
  • the surface region of the FAB8, for example, the FAB8 formed by the Group 15 and 16 elements contained in the coating layer 5 is used.
  • the surface gold-enriched region 9 is formed in a range of 10 ⁇ m or less (or 10% or less with respect to the diameter of FAB8) in the depth direction from the surface, although it depends on the diameter of the surface. Since the surface gold-enriched region 9 is maintained even after the FAB 8 and the electrode 2 are bonded, the gold-enriched bonding region 7 can be formed in the vicinity of the bonding interface between the electrode 2 and the ball compression portion 6. That is, it becomes possible to obtain a wire bonding structure 1 having a gold-enriched bonding region 7.
  • the method and process of forming the gold-enriched bonding region 7 described above are merely examples, and the present invention is not limited thereto.
  • the gold-concentrated bonding region 7 can be formed even under the following conditions. Specifically, the gold-concentrated bonding region 7 can be formed by depositing gold on the surface of the aluminum electrode. However, gold coating on the electrodes is not recommended because it is very costly in terms of material cost and manufacturing cost.
  • the wire bonding structure 1 of the embodiment enhances the bonding reliability between the electrode 2 and the ball compression unit 6 described above by providing a gold-concentrated bonding region 7 in the vicinity of the bonding interface between the electrode 2 and the ball compression unit 6. Therefore, the method of forming the gold-enriched bonding region 7 is not particularly limited.
  • the method of calculating the gold content and the content of the 15th and 16th group elements in the total amount of the gold-coated silver bonding wire 3 will be described below.
  • the gold content is calculated.
  • the bonding wire 3 is put into dilute nitric acid to dissolve the core material 4, and then the solution is collected. Hydrochloric acid is added to this solution, and ultrapure water is used to make a constant volume solution.
  • the coating layer 5 is dissolved in rare aqua regia and made into a constant volume solution with ultrapure water.
  • the gold content is measured by performing quantitative analysis of gold in these constant volumes by ICP-AES (ICP-AES: Inductively Coupled Plasma Atomic Emission Spectroscopy).
  • the contents of the 15th and 16th group elements are calculated.
  • the bonding wire 3 is put into dilute nitric acid, the core material 4 is melted, and then the coating layer 5 is extracted. Further, after the coating layer 5 is thermally decomposed with dilute aqua regia, the measurement is carried out using a solution having a constant volume with ultrapure water. Quantitative analysis of selenium, tellurium, arsenic, and antimony in this constant volume solution is measured using ICP mass spectrometry (ICP-MS: Inductively Coupled Plasma Mass Spectrometry).
  • the content of selenium, tellurium, arsenic, and antimony in the core material 4 is measured by ICP-MS or ICP-AES using a liquid obtained by putting the bonding wire 3 in dilute nitric acid and melting the core material 4. Then, the gold content and the content of selenium, tellurium, arsenic, and antimony in the entire bonding wire 3 are calculated from the gold content of the coating layer 5 and the core material 4 and the contents of selenium, tellurium, arsenic, and antimony. ..
  • a hydride generator is attached to ICP-AES to generate hydrides of selenium, tellurium, arsenic, and antimony for analysis.
  • the sulfur (S) content of the core material 4 and the coating layer 5 is measured with respect to the bonding wire 3 by using a combustion infrared absorption method.
  • the weight of the bonding wire 3 per measurement is preferably 0.5 g or more. If the sample is difficult to dissolve, a combustion improver may be used if necessary.
  • the manufacturing method of the bonding wire will be described.
  • silver is used as the core material 4
  • silver of a predetermined purity is dissolved, and when a silver alloy is used, silver of a predetermined purity is dissolved together with an additive element to form a silver core material or a silver alloy.
  • a core material is obtained.
  • a heating furnace such as an arc heating furnace, a high frequency heating furnace, a resistance heating furnace, or a continuous casting furnace is used.
  • the melted core material is cast and solidified from a heating furnace so that it has a predetermined wire diameter, or the melted core material is cast into a mold to make an ingot, and the ingot is rolled and then a predetermined wire.
  • a silver wire (including a sterling silver wire and a silver alloy wire) is obtained by drawing the wire to a diameter.
  • a plating method (wet method) or a vapor deposition method (dry method) is used.
  • the plating method may be either an electrolytic plating method or an electroless plating method. Electroplating such as strike plating and flash plating is preferable because the plating speed is high, and when applied to gold plating, the adhesion of the gold layer to the silver wire is good.
  • the gold plating solution contains a plating additive containing at least one selected from sulfur, selenium, tellurium, arsenic, and antimony. Use the plated solution.
  • the content of Group 15 and Group 16 elements in the coating layer 5 can be adjusted by adjusting the type and amount of the plating additive, and the content of Group 15 and Group 16 elements in the wire 3 can be adjusted. Can be adjusted.
  • vapor deposition method physical vapor deposition (PVD) such as a sputtering method, an ion plating method, or a vacuum vapor deposition method, or chemical vapor deposition (CVD) such as thermal CVD, plasma CVD, or metalorganic vapor deposition (MOCVD) is used.
  • PVD physical vapor deposition
  • CVD chemical vapor deposition
  • thermal CVD plasma CVD
  • MOCVD metalorganic vapor deposition
  • a gold-coated silver bonding wire 3 having a coating layer 5 on the surface of the silver core material 4 is manufactured by drawing a silver wire material coated with a gold layer to the final wire diameter and heat-treating it if necessary.
  • the wire drawing process may be performed at the stage of the silver wire rod, or the silver wire rod may be wire drawn to a certain diameter to form a gold layer and then drawn to the final wire diameter.
  • the wire drawing process and the heat treatment may be performed step by step.
  • the processing rate of the wire drawing process is determined according to the final wire diameter of the gold-coated silver bonding wire 3 to be manufactured, the application, and the like.
  • the processing rate of wire drawing is preferably 90% or more as the processing rate until the silver wire is processed to the final wire diameter.
  • This processing rate can be calculated as a reduction rate of the wire cross-sectional area. It is preferable that the wire drawing process is performed by using a plurality of diamond dies so as to gradually reduce the wire diameter.
  • the surface reduction rate (processing rate) per diamond die is preferably 5% or more and 15% or less.
  • the final heat treatment is performed in consideration of the strain removing heat treatment for removing the strain of the metal structure remaining inside the wire 3 and the required wire characteristics in the final wire diameter.
  • the strain removing heat treatment it is preferable to determine the temperature and time in consideration of the required wire characteristics.
  • heat treatment may be performed according to the purpose at any stage of wire production. Examples of such a heat treatment include a strain removing heat treatment in the wire drawing process, a diffusion heat treatment for increasing the bonding strength after forming a gold layer, and the like. By performing the diffusion heat treatment, the bonding strength between the core material 4 and the coating layer 5 can be improved.
  • the heat treatment a run-run heat treatment in which a wire is passed through a heating atmosphere heated to a predetermined temperature to perform the heat treatment is preferable because the heat treatment conditions can be easily adjusted.
  • the heat treatment time can be calculated from the passing speed of the wire and the passing distance of the wire in the heating container.
  • An electric furnace or the like is used as the heating container.
  • the FAB 8 is formed at one end of the gold-coated silver bonding wire 3 described above.
  • the FAB 8 is formed by generating an arc discharge between the tip of the wire 3 and the discharge torch and melting the tip of the wire 3.
  • the FAB8 formed at one end of the gold-coated silver bonding wire 3 is bonded to the electrode 2 by a thermocompression bonding method using ultrasonic waves or the like.
  • the ball compression portion 6 joined to the electrode 2 can be formed by joining the FAB 8 in contact with the electrode 2 to the electrode 2 by ultrasonic waves and heat while deforming the FAB 8 in contact with the electrode 2 by the pressure at the time of thermocompression bonding using ultrasonic waves. ..
  • FIGS. 5 to 7 are cross-sectional views showing a stage before resin sealing of the semiconductor device of the embodiment
  • FIG. 6 is a cross-sectional view showing a stage of resin sealing of the semiconductor device of the embodiment
  • FIG. 7 is a semiconductor device of the embodiment. It is a cross-sectional view which shows the junction
  • the semiconductor device 10 of the embodiment is arranged on the circuit board 12 having the external electrode 11 and at least one.
  • a plurality of semiconductor chips 14 (14A, 14B, 14C) each having an electrode (chip electrode) 13 are connected to an external electrode 11 of the circuit board 12, an electrode 13 of the semiconductor chip 14, and an electrode 13 of the plurality of semiconductor chips 14.
  • the bonding wire 15 is provided.
  • the circuit board 12 for example, a printed wiring board or a ceramic circuit board having a wiring network provided on the surface or inside of an insulating base material such as a resin material or a ceramic material is used.
  • FIGS. 5 and 6 show a semiconductor device 10 in which a plurality of semiconductor chips 14 are mounted on a circuit board 12, but the configuration of the semiconductor device 10 is not limited to this.
  • the semiconductor chip may be mounted on a lead frame, in which case the electrodes of the semiconductor chip are connected to an outer lead that functions as an external electrode of the lead frame via a bonding wire 15.
  • the number of semiconductor chips mounted on the circuit board or lead frame may be one or a plurality.
  • the bonding wire 15 is applied to at least one of the external electrode 11 of the circuit board 12 and the electrode 13 of the semiconductor chip 14, the lead frame and the electrode of the semiconductor chip, and the electrodes 13 of the plurality of semiconductor chips 14.
  • the semiconductor chips 14A and 14C are mounted in the chip mounting region of the circuit board 12 via the die bonding material 16.
  • the semiconductor chip 14B is mounted on the semiconductor chip 14A via a die bonding material 16.
  • One electrode 13 of the semiconductor chip 14A is connected to the external electrode 11 of the circuit board 12 via the bonding wire 15, and the other electrode 13 is connected to the electrode 13 of the semiconductor chip 14B via the bonding wire 15.
  • the other electrode 13 is connected to the electrode 13 of the semiconductor chip 14C via a bonding wire 15.
  • the other electrode 13 of the semiconductor chip 14B is connected to the external electrode 11 of the circuit board 12 via the bonding wire 15.
  • the other electrode 13 of the semiconductor chip 14C is connected to the external electrode 11 of the circuit board 12 via the bonding wire 15.
  • the semiconductor chip 14 includes an integrated circuit (IC) made of a silicon (Si) semiconductor, a compound semiconductor, or the like.
  • the chip electrode 13 is made of, for example, an aluminum electrode having an aluminum (Al) layer and an aluminum alloy layer such as AlSiCu or AlCu on the outermost surface.
  • the aluminum electrode is formed by, for example, coating the surface of a silicon (Si) substrate with an electrode material such as Al or an Al alloy so as to electrically connect to the internal wiring.
  • the semiconductor chip 14 communicates data with an external device via the external electrode 11 and the bonding wire 15, and supplies electric power from the external device.
  • the external electrode 11 of the circuit board 12 is electrically connected to the electrode 13 of the semiconductor chip 14 mounted on the circuit board 12 via the bonding wire 15.
  • one end of the bonding wire 15 is ball-bonded (first bonded) to the chip electrode 13, and the other end is wedge-bonded (second bonded) to the external electrode 11.
  • One end of the bonding wire 15 is ball-bonded (first bonded) to the chip electrode 13 of the semiconductor chip 14, and the other end is the other.
  • Wedge bonding (second bonding) is performed on the chip electrode 13 of the semiconductor chip 14 of the above.
  • the electrode 13 of the semiconductor chip 14 includes a form in which a bump is previously bonded to an electrode pad on the semiconductor chip 14 (not shown).
  • the wire bonding structure 1 shown in FIG. 1 is formed. That is, as shown in FIG. 7, a wire bonding structure 1 having a bonding wire 15, a chip electrode 13, and a ball compression portion 6 bonded to the chip electrode 13 is formed.
  • the semiconductor device 10 is manufactured by forming the sealing resin layer 17 on the circuit base material 12 so that the plurality of semiconductor chips 14 and the bonding wires 15 are resin-sealed.
  • Specific examples of the semiconductor device 10 include logic ICs, analog ICs, discrete semiconductors, semiconductor memories, optical semiconductors, and the like.
  • the wire bonding structure 1 of the above-described embodiment is applied to the wire bonding structure 1 in the semiconductor device 10. That is, as shown in FIG. 1, the concentration of gold is relative to the total amount of gold, silver, and aluminum in the vicinity of the bonding interface between the ball compression portion 6 provided at one end of the bonding wire 15 and the chip electrode 13.
  • a gold-enriched bonding region 7 of 5 atomic% or more is provided.
  • Examples 1 to 26 are examples, and examples 27 to 32 are comparative examples.
  • Examples 1 to 26 As a core material, a silver or silver alloy core material produced by continuous casting was prepared, and continuous wire drawing was performed to process an intermediate wire diameter of 0.05 mm to 1.0 mm. Furthermore, a gold electroplating bath in which appropriate amounts of each of sulfur, selenium, tellurium, arsenic, and antimony additives are added to a silver wire having an intermediate wire diameter is used, and the silver wire is immersed while continuously transmitting the wire. Then, a current was passed through the silver wire at a current density of 0.20 A / dm 2 or more and 2.0 A / dm 2 or less to form a gold coating layer. After that, the wire drawn to a final wire diameter of ⁇ 20 ⁇ m was subjected to final heat treatment to prepare gold-coated silver bonding wires of Examples 1 to 26.
  • Gold content in gold-coated silver bonding wire gold is derived from the coating layer and is not contained in the silver core material, and contains palladium, indium, and Group 15 and 16 elements that are additives to the silver core material.
  • the amount is the method described above and the method described above (
  • FAB production conditions FAB was prepared under the above-mentioned conditions and bonded to the electrodes under the above-mentioned bonding conditions (see [0024] and [0040]).
  • the ball formability can be evaluated by the roundness after the ball is crimped. For the 30 first joints, observe the joined balls from above, measure the maximum width of the crimping balls and the width orthogonal to this, and the ratio of the maximum width to the width orthogonal to this (maximum width / orthogonal width). ) was asked. If the average value of the above 30 pieces of this ratio is 1.00 or more and less than 1.15, it is good ( ⁇ ), and if it is 1.15 or more, there is a problem and it is bad (X).
  • the gold analysis value of the gold-enriched joint region in Table 1 the value of the set with the highest gold concentration among the four sets of joint structures was adopted, and the gold concentration at the measurement point of the line analysis near the joint interface of that set was adopted. 3 points were selected from the highest order, and the average value of the 3 points was described.
  • the evaluation of whether or not there is a gold-enriched joint region between both ends of the compression part and the above-mentioned one-eighth part is passed ( ⁇ ) if all four sets of balls are used, and if there is no one set. It was rejected (X).
  • the occupancy rate of the gold-enriched joint region it was described as passing ( ⁇ ) when all four sets of joining structures were 25% or more, and failing (X) when even one set was less than 25%. (Refer to [0027] to [0032] for details of each evaluation method).
  • EFO-Gap Adjusts the current to a predetermined value in the range of 30 to 90 mA and the discharge time in the range of 50 to 1000 ⁇ s, EFO-Gap is 25 to 45 mil (about 635 to 1143 ⁇ m), and the tail length is 6 to 12 mil (about 152 to 152 to). 305 ⁇ m).
  • the conditions for the first joining are, for example, in Example 1 in which the wire wire diameter ⁇ is 20 ⁇ m, a free air ball having a ball diameter of 36 ⁇ m is formed, the height of the ball compression portion is 10 ⁇ m, and the joint surface of the ball compression portion is formed.
  • the bonding conditions were adjusted so that the maximum width in the parallel direction was 45 ⁇ m and the ball share strength was 15 gf or more.
  • the Al-0.5 mass% Cu alloy electrode on the chip only the adjacent bond portions are electrically connected, and two adjacent wires electrically form one circuit. A total of 320 circuits are formed.
  • the Si chip on the BGA substrate was resin-sealed using a commercially available transfur mold machine (Daiichi Seiko Co., Ltd., GPGP-PRO-LAB80) to obtain a test piece.
  • a commercially available halogen-free resin chlorine concentration of 15 ppm or less, ph6 or more and 7 or less
  • the height of the ball compression portion is 7 to 13 ⁇ m, and the maximum width in the direction parallel to the joint surface of the ball compression portion is 1.2 times that of the formed free air ball. did.
  • the gold concentration in the vicinity of the bonding interface between the electrode containing aluminum and the ball compression portion is 5 with respect to the total of aluminum, silver and gold.
  • a gold-enriched bonding region having a content of 0.0 atomic% or more can be formed. With such a bonding structure, the HAST evaluation is good, and it is possible to provide a highly reliable semiconductor device in which the specific resistance of the connection portion does not increase even when exposed to a harsh environment such as high temperature and high humidity for a long time. ..
  • the gold-enriched bonding region is near both ends of the bonding interface, and the gold-concentrated bonding region occupies 25% or more of the width of the ball compression portion at the bonding interface, so that HAST It can be seen that the evaluation is good. Further, adding an additive element of palladium or indium to the core material of the wire is also one of the factors for improving the HAST evaluation. Regarding the gold concentration in the gold-enriched bonding region, the higher the gold concentration, the better the HAST evaluation tends to be. It is considered that a higher gold concentration has a better effect on the HAST evaluation than adding palladium or the like to the core material.
  • the gold layer (concentration-converted value in Table 1) covering the wire is less than 2.0% by mass
  • the gold concentration in the gold-concentrated bonding region becomes less than 5 atomic% and HAST.
  • the evaluation fails, and conversely, if the gold layer covering the wire is too thick (here, if it exceeds 7% by mass in terms of concentration), eccentricity etc. will occur during FAB formation, and ball formation will deteriorate. I understand.
  • the amount of Group 15 and Group 16 elements added is also important. If it is less than 4 mass ppm, the gold concentration in the gold-enriched bonding region becomes less than 5 atomic%, and the HAST evaluation also fails. If it exceeds 80 mass ppm, crack defects occur on the wire surface. Of course, even when the Group 15 and Group 16 elements are not added, the gold-concentrated bonding region becomes less than 5 atomic%, and the HAST evaluation also fails.
  • the concentration of gold is high in the vicinity of the bonding interface between the electrode and the ball compression portion while suppressing an increase in the specific resistance of the bonding wire.
  • the bonding reliability between the electrode and the ball compression portion can be improved.
  • the semiconductor device of the present invention to which such a wire bonding structure is applied it is possible to improve the bonding reliability between the electrode and the ball compression portion by the gold-concentrated bonding region, and eventually the reliability of the semiconductor device itself. become.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Wire Bonding (AREA)

Abstract

In the present invention, the reliability of joining between a bonding wire for which the cost of materials was suppressed and an electrode is maintained over an extended period of time even in a harsh environment while increases in resistivity are suppressed despite joining of the bonding wire and the electrode. This wire joining structure 1 has an aluminum-containing electrode 2, a bonding wire 3, and a ball compression part 6 joined to the electrode 2. The bonding wire 3 has a core material 4 having silver as a main component, and a coating layer 5 having gold as a main component. The bonding wire 3 contains at least one group-15 or -16 element selected from sulfur, tellurium, selenium, arsenic, and antimony. With respect to the entirety of the wire, the gold concentration is 2.0-7.0 mass% inclusive, and the group-15 or -16 element concentration is 4-80 mass ppm inclusive in total. A gold-concentrated joining region in which the gold concentration reaches or exceeds 5.0 at% with respect to the total of aluminum, silver, and gold is present near the joining interface of the electrode 2 and the ball compression part 6.

Description

ワイヤ接合構造とそれに用いられるボンディングワイヤ及び半導体装置Wire bonding structure and bonding wires and semiconductor devices used for it
　本発明は、ワイヤ接合構造とそれに用いられるボンディングワイヤ及び半導体装置に関する。 The present invention relates to a wire bonding structure and a bonding wire and a semiconductor device used therein.
　半導体チップの電極とリードフレームや回路基板等の回路基材の外部電極とは、例えばボンディングワイヤにより接続される。ボンディングワイヤでは、例えばボール接合と呼ばれる方式により半導体チップの電極にボンディングワイヤの一端を接合（第１接合）し、ウェッジ接合と呼ばれる方式によりボンディングワイヤの他端を回路基材の外部電極に接合（第２接合）することが一般的である。ボール接合においては、ボンディングワイヤの一端を放電等により溶融させ、表面張力等により球形状に凝固させてボールを形成する。凝固したボールはフリーエアーボール（Ｆｒｅｅ　Ａｉｒ　Ｂａｌｌ：ＦＡＢ）と呼ばれ、超音波併用熱圧着ボンディング法等により半導体チップの電極に接続されてワイヤ接合構造が形成される。ここで、ボンディングワイヤに設けられたＦＡＢを電極に接合した構造を、ここではワイヤ接合構造と呼び。さらに、ボンディングワイヤが接続された半導体チップを、ボンディングワイヤや回路基材の一部と共に樹脂封止することによって、半導体装置が構成される。 The electrodes of the semiconductor chip and the external electrodes of the circuit base material such as the lead frame and the circuit board are connected by, for example, a bonding wire. In the bonding wire, for example, one end of the bonding wire is bonded to the electrode of the semiconductor chip (first bonding) by a method called ball bonding, and the other end of the bonding wire is bonded to the external electrode of the circuit substrate by a method called wedge bonding (first bonding). Second bonding) is common. In ball bonding, one end of the bonding wire is melted by discharge or the like and solidified into a spherical shape by surface tension or the like to form a ball. The solidified ball is called a free air ball (FREE Air Ball: FAB), and is connected to an electrode of a semiconductor chip by a thermocompression bonding method or the like combined with ultrasonic waves to form a wire bonding structure. Here, the structure in which the FAB provided on the bonding wire is bonded to the electrode is referred to as a wire bonding structure here. Further, the semiconductor device is configured by resin-sealing the semiconductor chip to which the bonding wire is connected together with the bonding wire and a part of the circuit base material.
　近年、半導体装置には低消費電力化及び信号処理速度の高速化が求められており、そのような半導体装置に使用されるボンディングワイヤは電気抵抗（比抵抗）が低く（例えば、純度９９．９９質量％の４ＮＡｕワイヤ以下）、かつ、過酷な環境でも長時間にわたり比抵抗が低いまま保持されること、すなわち、高信頼性であることが求められる。高信頼性とは、高温多湿な環境下においても腐食（硫化や酸化）されず、長期間電気抵抗が上昇しないことを意味する。しかし、従来から一般的に用いられている金ワイヤは材料コストが高く、また銅ワイヤや被覆銅ワイヤは材料が硬く、半導体チップにダメージを与えてしまうという課題がある。また、銀ワイヤはコストが安く、柔らかいため、ボンディングワイヤとして好適であるものの、純銀ワイヤは大気中に長期間放置されると表面が硫化するという課題を有する。硫化対策として製品化されている銀合金ボンディングワイヤは純銀にパラジウムや金等の金属元素を添加しているため、銀の含有量は９０質量％から９７質量％となる。硫化対策はやや改善されたものの、銀合金ボンディングワイヤは、添加元素の含有量の影響で比抵抗が高くなるという難点があり、近年の半導体装置の要求に十分には適合しない。貴金属の含有量を低下させ、金ワイヤと同等の比抵抗を有する銀合金ワイヤが提案されているが、今度は耐腐食性の問題があることから半導体装置を構成するモールド樹脂、すなわち高信頼性に影響を及ぼす元素が入っていない樹脂の選定等が必要になる点やボンディングワイヤと電極の界面で生成される金属間化合物のため高信頼性評価基準を満たすことが困難であるというような課題もある。 In recent years, semiconductor devices have been required to have low power consumption and high signal processing speed, and bonding wires used in such semiconductor devices have low electrical resistance (specific resistance) (for example, purity 99.99). It is required to have a mass% of 4NAu wire or less) and to maintain a low specific resistance for a long time even in a harsh environment, that is, to have high reliability. High reliability means that it is not corroded (sulfurized or oxidized) even in a hot and humid environment, and its electrical resistance does not increase for a long period of time. However, the gold wire generally used conventionally has a high material cost, and the copper wire and the coated copper wire have a problem that the material is hard and damages the semiconductor chip. Further, although silver wire is suitable as a bonding wire because of its low cost and softness, sterling silver wire has a problem that its surface is sulfurized when left in the atmosphere for a long period of time. Since the silver alloy bonding wire commercialized as a measure against sulfurization contains metal elements such as palladium and gold to pure silver, the silver content is 90% by mass to 97% by mass. Although the measures against sulfurization have been slightly improved, the silver alloy bonding wire has a drawback that the specific resistance becomes high due to the influence of the content of additive elements, and does not sufficiently meet the demands of recent semiconductor devices. A silver alloy wire that reduces the content of precious metals and has a specific resistance equivalent to that of gold wire has been proposed, but this time there is a problem of corrosion resistance, so the molded resin that constitutes the semiconductor device, that is, high reliability It is difficult to meet the high reliability evaluation criteria because it is necessary to select a resin that does not contain elements that affect the bonding wire and the intermetallic compound generated at the interface between the bonding wire and the electrode. There is also.
　上記したような課題を解決するために、銀ワイヤの表面に耐腐食性の高いパラジウム等の白金族元素や金等の被覆層を形成することが提案されている。白金族元素や金等の被覆層は、溶融しない固体のままの状態であれば銀ワイヤ表面の硫化を抑制し得る。よって、ウェッジボンディング（第２接合）のように溶融しないで接合する場合には効果を発揮する。ところが、半導体チップ上にある電極と接合する（第１接合）際に問題が生じる。ボンディングワイヤは先に説明した通り、ワイヤの一端を放電等により溶融させ、表面張力等により球形状に凝固させてボールを形成する。凝固したボールはフリーエアーボール（ＦＡＢ）といい、ＦＡＢを超音波併用熱圧着ボンディング法等により半導体チップの電極に接続されてワイヤ接合構造が形成される。ボールを形成しないで接合するウェッジ接合だと接合面積が小さくなり接合強度が弱まるため、一般的にボール状にして接合面積を広くすることで接合力を高める方法が用いられている。ＦＡＢ形成時に白金族元素や金を被覆したワイヤ全体を溶融するため、被覆されている白金族元素や金も融点差等の理由により時間差はあるものの、ほぼ同時に溶かされボール内部に白金族元素や金が入り込み、ボール表面の白金族元素や金の濃度が相対的に低くなる。ＦＡＢ表面の耐腐食性のある白金族元素や金の濃度が低くなり、銀の濃度が相対的に高くなったＦＡＢを半導体チップのアルミニウム電極に接合した場合、ＦＡＢと電極との接合界面近傍に、相対的に多くなった銀と電極を構成するアルミニウムとで銀とアルミニウムの金属間化合物が形成されやすくなる。銀とアルミニウムの金属間化合物はハロゲン元素や水分等に腐食されやすく、比抵抗の上昇を招き通電不良を起こす原因となる。特に、自動車等の高温多湿の環境下で使用する場合、ボンディングワイヤと電極との接合界面に形成された金属間化合物がより腐食されやすくなる。これらの現象は電気抵抗（比抵抗）の上昇を招き、通電不良の原因となる。よって、ボンディングワイヤと電極との界面において高温多湿のような過酷な環境下でも長時間にわたり比抵抗が上昇しない接合構造の形成が求められている。 In order to solve the above-mentioned problems, it has been proposed to form a coating layer such as platinum group element such as palladium or gold having high corrosion resistance on the surface of the silver wire. A coating layer such as a platinum group element or gold can suppress sulfide on the surface of silver wire if it remains as a solid that does not melt. Therefore, it is effective when bonding without melting as in wedge bonding (second bonding). However, a problem arises when joining the electrode on the semiconductor chip (first joining). As described above, the bonding wire is formed by melting one end of the wire by electric discharge or the like and solidifying it into a spherical shape by surface tension or the like to form a ball. The solidified ball is called a free air ball (FAB), and the FAB is connected to the electrodes of the semiconductor chip by a thermocompression bonding method or the like combined with ultrasonic waves to form a wire bonding structure. Wedge joining without forming balls reduces the joining area and weakens the joining strength. Therefore, a method of increasing the joining force by making the joining area into a ball shape and widening the joining area is generally used. Since the entire wire coated with platinum group element or gold is melted during FAB formation, the coated platinum group element or gold is also melted almost at the same time, although there is a time lag due to the difference in melting point, etc. Gold enters and the concentration of platinum group elements and gold on the ball surface becomes relatively low. When a FAB with a low concentration of corrosion-resistant platinum group elements and gold on the surface of the FAB and a relatively high concentration of silver is bonded to the aluminum electrode of a semiconductor chip, it is located near the bonding interface between the FAB and the electrode. , The relatively large amount of silver and the aluminum constituting the electrode facilitates the formation of an intermetallic compound of silver and aluminum. Intermetallic compounds of silver and aluminum are easily corroded by halogen elements, moisture, etc., which causes an increase in specific resistance and causes poor energization. In particular, when used in a hot and humid environment such as an automobile, the intermetallic compound formed at the bonding interface between the bonding wire and the electrode is more likely to be corroded. These phenomena cause an increase in electrical resistance (specific resistance) and cause poor energization. Therefore, it is required to form a bonding structure at the interface between the bonding wire and the electrode so that the specific resistance does not increase for a long time even in a harsh environment such as high temperature and humidity.
　例えば、特開平１０－３２６８０３号公報（特許文献１）は、Ａｇを１１～１８．５質量％の範囲で含有し、残部が金及び不可避不純物からなる金銀合金ワイヤ、さらにＣｕ、Ｐｄ、Ｐｔの少なくとも１種を総計で０．０１～４質量％、Ｃａ、Ｉｎ、希土類元素の少なくとも１種を総計で０．０００５～０．０５質量％、又はＭｎ、Ｃｒの少なくとも１種を総計で０．０１～０．２質量％の範囲で含有させた金銀合金ワイヤを開示している。特許文献１は特定量の銀を含有させることによって、銀によるアルミニウム電極との接合信頼性を改善しつつ低コスト化を図った金銀合金ワイヤを提供している。しかしながら、依然として主成分は金であることから、銀ワイヤ、銀合金ワイヤ、被覆銀ワイヤ等に比べて高価であり、材料コストが高いという課題が解決されていない。また、コストの問題だけではなく比抵抗が上昇するという懸念もある。 For example, Japanese Patent Application Laid-Open No. 10-326803 (Patent Document 1) describes a gold-silver alloy wire containing Ag in the range of 11 to 18.5% by mass and the balance being gold and unavoidable impurities, and Cu, Pd, and Pt. At least one kind is 0.01 to 4% by mass in total, at least one kind of Ca, In and rare earth elements is 0.0005 to 0.05% by mass in total, or at least one kind of Mn and Cr is 0. A gold-silver alloy wire contained in the range of 01 to 0.2% by mass is disclosed. Patent Document 1 provides a gold-silver alloy wire in which a specific amount of silver is contained to improve the bonding reliability of silver with an aluminum electrode and to reduce the cost. However, since the main component is still gold, the problem of high material cost is not solved because it is more expensive than silver wire, silver alloy wire, coated silver wire and the like. In addition to cost issues, there is also concern that resistivity will increase.
　また、従来の被覆銀ボンディングワイヤに関して、例えば国際公開２０１３／１２９２５３号（特許文献２）は、Ａｇ又はＡｇ合金ワイヤの表面にＰｄ、Ａｕ、Ｚｎ、Ｐｔ、Ｎｉ、Ｓｎの１種以上又はこれらの合金もしくはこれら金属の酸化物又は窒化物を有するワイヤ被覆層を有するボンディングワイヤを開示している。特許文献２には、パワー半導体装置内の接続に被覆層を有するＡｇ又はＡｇ合金ワイヤを用いると共に、ボール接合ではなくウェッジ接合を用いることによって、Ａｌ電極とＡｇワイヤとの接合界面における金属間化合物の形成を抑制して接合信頼性を高めることが開示されている。しかしながら、特許文献２は上記したようにＡｇワイヤのウェッジ接合を前提としているため、被覆ワイヤを溶融凝固しなければならないＦＡＢを形成しないため、被覆層の構成元素が芯材であるＡｇワイヤ中に入り込むことを考慮していない。従って、特許文献２はＦＡＢを電極に接合した際の接合界面の構成元素を考慮しておらず、接合界面の構成元素に基づいて信頼性を向上させることを考慮していない。さらになお構成元素のＡｇワイヤ中への入り込みを抑制するための構成も開示していない。 Further, regarding the conventional coated silver bonding wire, for example, International Publication No. 2013/129253 (Patent Document 2) describes that one or more of Pd, Au, Zn, Pt, Ni, Sn or one or more of Pd, Au, Zn, Pt, Ni, Sn on the surface of Ag or Ag alloy wire. A bonding wire having a wire coating layer having an alloy or an oxide or nitride of these metals is disclosed. Patent Document 2 uses an Ag or Ag alloy wire having a coating layer for connection in a power semiconductor device, and by using wedge bonding instead of ball bonding, an intermetallic compound at the bonding interface between the Al electrode and Ag wire. It is disclosed that the formation of the metal is suppressed and the joint reliability is enhanced. However, since Patent Document 2 presupposes wedge bonding of Ag wires as described above, it does not form FAB in which the coated wires must be melt-solidified. Therefore, the constituent elements of the coating layer are contained in the Ag wires as the core material. Not considering getting in. Therefore, Patent Document 2 does not consider the constituent elements of the bonding interface when the FAB is bonded to the electrode, and does not consider improving the reliability based on the constituent elements of the bonding interface. Furthermore, the configuration for suppressing the entry of the constituent elements into the Ag wire is not disclosed.
　さらに、特開２００１－１９６４１１号公報（特許文献３）は、Ａｇ線と、Ａｇ線を被覆するＡｕ膜とを有し、Ａｕ膜はＮａ、Ｓｅ、Ｃａ、Ｓｉ、Ｎｉ、Ｂｅ、Ｋ、Ｃ、Ａｌ、Ｔｉ、Ｒｂ、Ｃｓ、Ｍｇ、Ｓｒ、Ｂａ、Ｌａ、Ｙ、Ｃｅの少なくとも１つの元素を含むボンディングワイヤを開示している。特許文献３は、Ａｕ被覆したＡｇワイヤではＦＡＢの形状が軸対称にならないことから、Ａｕ膜に上記した元素を含有させてアーク放電が一点に集中することを抑制し、表面全体からアークを生じさせてＦＡＢの形状を安定化させることを開示している。しかし、特許文献３もまたＦＡＢ形成時に被覆層のＡｕがＡｇ線中に入り込むことを考慮しておらず、またＡｕのＡｇ線への入り込みを抑制するための構成を開示していない。従って、特許文献３は金被覆銀ワイヤを用いた際にＡｌ電極とＡｇワイヤとの接合界面に金属間化合物が形成されて接合信頼性が低下することを示唆していないだけでなく、さらにＡｌ電極とＡｇワイヤとの接合信頼性を高めるための構成も開示していない。また、上記したような添加元素は、その含有量によってはワイヤ自体の特性や被覆層の形成性等に悪影響を及ぼすおそれがある。このため、ワイヤ自体の特性や被覆層の形成性等に悪影響を及ぼすことなく、ＡｕのＡｇ線への入り込みを抑制してワイヤ接合構造の信頼性を高める技術が求められている。 Further, Japanese Patent Application Laid-Open No. 2001-196411 (Patent Document 3) has an Ag wire and an Au film covering the Ag wire, and the Au film is Na, Se, Ca, Si, Ni, Be, K, C. , Al, Ti, Rb, Cs, Mg, Sr, Ba, La, Y, Ce. In Patent Document 3, since the shape of the FAB is not axisymmetric with the Au-coated Ag wire, the above-mentioned element is contained in the Au film to suppress the concentration of the arc discharge at one point, and an arc is generated from the entire surface. It is disclosed that the shape of the FAB is stabilized by allowing the FAB to be formed. However, Patent Document 3 also does not consider that Au of the coating layer enters the Ag line during FAB formation, and does not disclose a configuration for suppressing the entry of Au into the Ag line. Therefore, Patent Document 3 not only does not suggest that an intermetal compound is formed at the bonding interface between the Al electrode and the Ag wire when the gold-coated silver wire is used, and the bonding reliability is lowered, and further, Al The configuration for enhancing the bonding reliability between the electrode and the Ag wire is also not disclosed. Further, the above-mentioned additive elements may adversely affect the characteristics of the wire itself, the formability of the coating layer, and the like depending on the content thereof. Therefore, there is a demand for a technique for suppressing the entry of Au into the Ag wire and improving the reliability of the wire bonding structure without adversely affecting the characteristics of the wire itself and the formability of the coating layer.
特開平１０－３２６８０３号公報Japanese Unexamined Patent Publication No. 10-326803 国際公開２０１３／１２９２５３号International Publication 2013/129253 特開２００１－１９６４１１号公報Japanese Unexamined Patent Publication No. 2001-196411
　本発明が解決しようとする課題は、材料コストを抑えたボンディングワイヤとアルミニウム電極とを接合しても比抵抗の上昇を抑制しつつ、過酷な環境下においても長期間ボンディングワイヤとアルミニウム電極との接合信頼性を保つことを可能にしたワイヤ接合構造と、それに用いられるボンディングワイヤ及び半導体装置を提供することにある。 The problem to be solved by the present invention is that the bonding wire and the aluminum electrode can be bonded for a long period of time even in a harsh environment while suppressing an increase in the specific resistance even when the bonding wire and the aluminum electrode are bonded at a low material cost. It is an object of the present invention to provide a wire bonding structure capable of maintaining bonding reliability, and a bonding wire and a semiconductor device used for the wire bonding structure.
　本発明のワイヤ接合構造は、アルミニウムを主成分として含む電極と、ボンディングワイヤと、前記ボンディングワイヤの一端に設けられ、前記電極に接合されたボール圧縮部とを具備する。本発明のワイヤ接合構造において、前記ボンディングワイヤは、銀を主成分とする芯材と、前記芯材の表面に設けられ、金を主成分とする被覆層とを有し、硫黄、テルル、セレン、ヒ素、及びアンチモンから選ばれる少なくとも１つの第１５及び１６族元素を含有する金被覆銀ボンディングワイヤであって、ワイヤ全体に対して、金濃度が２．０質量％以上７．０質量％以下であり、第１５及び１６族元素濃度が合計で４質量ｐｐｍ以上８０質量ｐｐｍ以下であり、前記電極と前記ボール圧縮部との接合界面近傍に、金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域を設けることで課題が解決される。 The wire bonding structure of the present invention includes an electrode containing aluminum as a main component, a bonding wire, and a ball compression portion provided at one end of the bonding wire and bonded to the electrode. In the wire bonding structure of the present invention, the bonding wire has a core material containing silver as a main component and a coating layer provided on the surface of the core material and containing gold as a main component, and has sulfur, tellurium, and selenium. A gold-coated silver bonding wire containing at least one Group 15 and 16 element selected from, arsenic, and antimony, having a gold concentration of 2.0% by mass or more and 7.0% by mass or less with respect to the entire wire. The total concentration of the 15th and 16th group elements is 4% by mass or more and 80% by mass or less, and the concentration of gold is the total amount of gold, silver and aluminum in the vicinity of the junction interface between the electrode and the ball compression portion. The problem is solved by providing a gold-enriched bonding region of 5 atomic% or more.
　本発明の金被覆銀ボンディングワイヤは、本発明のワイヤ接続構造に用いられる金被覆ボンディングワイヤであって、前記金被覆ボンディングワイヤは、銀を主成分として含む芯材と、前記芯材の表面に設けられ、金を主成分として含む被覆層とを有し、前記金被覆銀ボンディングワイヤは、硫黄、テルル、セレン、ヒ素、及びアンチモンから選ばれる少なくとも１つの第１５及び１６族元素を含有し、前記金被覆銀ボンディングワイヤにおいて、ワイヤ全体に対して、金の濃度が２．０質量％以上７．０質量％以下であり、第１５及び１６族元素の濃度が４質量ｐｐｍ以上８０質量ｐｐｍ以下であり、前記金被覆銀ボンディングワイヤは、アルミニウムを主成分とする電極にボールボンディングで接合することによりボール圧縮部を形成したとき、前記電極と前記ボール圧縮部との接合界面近傍に、金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域が形成される、金被覆銀ボンディングワイヤである。 The gold-coated silver bonding wire of the present invention is a gold-coated bonding wire used in the wire connection structure of the present invention, and the gold-coated bonding wire is formed on a core material containing silver as a main component and a surface of the core material. The gold-coated silver bonding wire is provided and has a coating layer containing gold as a main component, and the gold-coated silver bonding wire contains at least one Group 15 and 16 element selected from sulfur, tellurium, selenium, arsenic, and antimony. In the gold-coated silver bonding wire, the concentration of gold is 2.0% by mass or more and 7.0% by mass or less, and the concentrations of Group 15 and 16 elements are 4% by mass or more and 80% by mass or less with respect to the entire wire. In the gold-coated silver bonding wire, when a ball compression portion is formed by bonding to an electrode containing aluminum as a main component by ball bonding, gold is placed in the vicinity of the bonding interface between the electrode and the ball compression portion. A gold-coated silver bonding wire having a gold-concentrated bonding region having a concentration of 5 atomic% or more based on the total amount of gold, silver, and aluminum.
　本発明の半導体装置は、少なくとも１つの電極を有する１つ又は複数の半導体チップと、リードフレーム又は基板と、前記半導体チップの電極と前記リードフレームとの間、前記半導体チップの電極と前記基板の電極との間、及び前記複数の半導体チップの電極間から選ばれる少なくとも１つを、銀を主成分として含む芯材と、前記芯材の表面に設けられ、金を主成分として含む被覆層とを有するボンディングワイヤで接続した半導体装置であって、前記電極と前記ボンディングワイヤとの接続構造は、前記電極に前記ボンディングワイヤの一端を接合するように設けられたボール圧縮部を備え、前記電極と前記ボール圧縮部との接合界面近傍に、金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域が設けられている。 The semiconductor device of the present invention comprises one or more semiconductor chips having at least one electrode, a lead frame or a substrate, between the electrodes of the semiconductor chip and the lead frame, the electrodes of the semiconductor chip and the substrate. At least one selected from between the electrodes and between the electrodes of the plurality of semiconductor chips is provided with a core material containing silver as a main component and a coating layer provided on the surface of the core material and containing gold as a main component. The semiconductor device is connected by a bonding wire, and the connection structure between the electrode and the bonding wire includes a ball compression portion provided to bond one end of the bonding wire to the electrode, and is provided with the electrode. A gold-concentrated bonding region having a gold concentration of 5 atomic% or more with respect to the total amount of gold, silver, and aluminum is provided in the vicinity of the bonding interface with the ball compression portion.
　本発明のワイヤ接合構造及びそれに用いられるボンディングワイヤによれば、ボンディングワイヤの比抵抗の上昇を抑えた上で、電極とボール圧縮部との接合界面近傍に金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域を設けることができる。このような金濃化接合領域を設けることによって、電極とボール圧縮部との接合信頼性を高めることができる。また、そのようなワイヤ接合構造を適用した本発明の半導体装置によれば、金濃化接合領域による電極とボール圧縮部との接合信頼性、ひいては半導体装置自体の信頼性を向上させることが可能になる。 According to the wire bonding structure of the present invention and the bonding wire used therein, the concentration of gold in the vicinity of the bonding interface between the electrode and the ball compression portion is gold, silver, and aluminum while suppressing an increase in the specific resistance of the bonding wire. A gold-concentrated bonding region of 5 atomic% or more can be provided with respect to the total amount. By providing such a gold-enriched bonding region, the bonding reliability between the electrode and the ball compression portion can be improved. Further, according to the semiconductor device of the present invention to which such a wire bonding structure is applied, it is possible to improve the bonding reliability between the electrode and the ball compression portion by the gold-concentrated bonding region, and eventually the reliability of the semiconductor device itself. become.
実施形態のワイヤ接合構造を示す断面図である。It is sectional drawing which shows the wire bonding structure of an embodiment. 実施形態のワイヤ接合構造におけるボール圧縮部から電極に向けて実施したライン分析の濃度プロファイルの一例を示す図である。It is a figure which shows an example of the density profile of the line analysis performed from the ball compression part toward the electrode in the wire bonding structure of an embodiment. 実施形態のワイヤ接合構造における金濃化接合領域の形成位置の一例を示す断面図である。It is sectional drawing which shows an example of the formation position of the gold-concentrated bonding region in the wire bonding structure of an embodiment. 実施形態のワイヤ接合構造に用いられる金被覆銀ボンディングワイヤの一端にＦＡＢを形成した状態を示す断面図である。It is sectional drawing which shows the state which FAB was formed at one end of the gold-coated silver bonding wire used for the wire bonding structure of an embodiment. 実施形態の半導体装置の樹脂封止する前の状態を示す断面図である。It is sectional drawing which shows the state before resin sealing of the semiconductor device of embodiment. 実施形態の半導体装置の樹脂封止した状態を示す断面図である。It is sectional drawing which shows the resin-sealed state of the semiconductor device of embodiment. 実施形態の半導体装置における半導体チップの電極とボンディングワイヤとの接合構造を拡大して示す断面図である。It is sectional drawing which enlarges and shows the bonding structure of the electrode of the semiconductor chip and the bonding wire in the semiconductor device of embodiment.
　以下、本発明の実施形態のワイヤ接合構造とそれに用いるボンディングワイヤ及び半導体装置について、図面を参照して説明する。各実施形態において、実質的に同一の構成部位には同一の符号を付し、その説明を一部省略する場合がある。図面は模式的なものであり、厚さと平面寸法との関係、各部の厚さの比率や縮尺、縦寸法と横寸法との比率や縮尺等は現実のものとは異なる場合がある。 Hereinafter, the wire bonding structure of the embodiment of the present invention and the bonding wire and semiconductor device used for the wire bonding structure will be described with reference to the drawings. In each embodiment, substantially the same constituent parts may be designated by the same reference numerals, and the description thereof may be partially omitted. The drawings are schematic, and the relationship between the thickness and the plane dimension, the ratio and scale of the thickness of each part, the ratio and scale of the vertical dimension and the horizontal dimension, etc. may differ from the actual ones.
（ワイヤ接合構造とそれに用いられるボンディングワイヤ）
　図１は実施形態のワイヤ接合構造を示す断面図である。実施形態のワイヤ接合構造１は、アルミニウム（Ａｌ）を主成分として含む電極２と、電極２に一端が接合されたボンディングワイヤ３とを備えている。ボンディングワイヤ３は、銀（Ａｇ）を主成分とする芯材（銀芯材とも記す）４と、芯材４の表面に設けられ、金（Ａｕ）を主成分として含む被覆層５とを有する金被覆銀ボンディングワイヤである。 (Wire bonding structure and bonding wire used for it)
FIG. 1 is a cross-sectional view showing a wire bonding structure of an embodiment. The wire bonding structure 1 of the embodiment includes an electrode 2 containing aluminum (Al) as a main component, and a bonding wire 3 having one end bonded to the electrode 2. The bonding wire 3 has a core material (also referred to as a silver core material) 4 containing silver (Ag) as a main component, and a coating layer 5 provided on the surface of the core material 4 and containing gold (Au) as a main component. It is a gold-coated silver bonding wire.
　電極２は、アルミニウムを主成分として含んでいる。電極２の構成例としては、半導体チップに設けられた電極が挙げられるが、これに限定されるものではない。電極２は、純アルミニウムにより構成してもよいし、またアルミニウムに添加元素を加えたアルミニウム合金により構成してもよい。ただし、アルミニウム電極２としての機能を損なわないように、電極２はアルミニウムを主成分として含むものとする。一般的に、電極２はＡｌ‐０．５％銅（Ｃｕ）、Ａｌ－１．０％シリコン（Ｓｉ）‐銅（Ｃｕ）で構成されているが、これらに限定されるものではない。 Electrode 2 contains aluminum as a main component. Examples of the configuration of the electrode 2 include, but are not limited to, an electrode provided on the semiconductor chip. The electrode 2 may be made of pure aluminum, or may be made of an aluminum alloy in which an additive element is added to aluminum. However, the electrode 2 contains aluminum as a main component so as not to impair the function as the aluminum electrode 2. Generally, the electrode 2 is composed of Al-0.5% copper (Cu) and Al-1.0% silicon (Si) -copper (Cu), but is not limited thereto.
　実施形態のワイヤ接合構造１は、電極２に金被覆銀ボンディングワイヤ３の一端を接合するように設けられたボール圧縮部６を備えている。ボール圧縮部６は、後に詳述するように、ボールボンディングする際にワイヤをキャピラリーと呼ばれる貫通した治具に通してボンディングするが、電極に押し付けて接合する際にキャピラリー内部の形状にボールが変形加工されて形作られる部分を言う。ボンディングワイヤ３の一端を放電等により溶融し、表面張力等により球状に凝固させて形成したＦＡＢを、超音波併用熱圧着ボンディング法等により電極２に押し付けてボンディングすることにより形成される。電極２とボール圧縮部６との接合界面近傍には、金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域７が設けられている。 The wire bonding structure 1 of the embodiment includes a ball compression unit 6 provided so as to bond one end of the gold-coated silver bonding wire 3 to the electrode 2. As will be described in detail later, the ball compression unit 6 bonds the wire through a penetrating jig called a capillary when the ball is bonded, but when the wire is pressed against the electrode to be bonded, the ball is deformed into the shape inside the capillary. The part that is processed and shaped. The FAB formed by melting one end of the bonding wire 3 by discharge or the like and solidifying it into a spherical shape by surface tension or the like is formed by pressing the FAB against the electrode 2 by a thermocompression bonding method using ultrasonic waves or the like to bond the bonding wire 3. A gold-enriched bonding region 7 having a gold concentration of 5 atomic% or more with respect to the total amount of gold, silver, and aluminum is provided in the vicinity of the bonding interface between the electrode 2 and the ball compression unit 6.
　接合界面近傍に金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域７を設けることによって、接合界面近傍における金濃度を高め、相対的に銀濃度を低く抑えることができる。従って、電極２とボール圧縮部６との接合信頼性を向上させることが可能になる。すなわち、銀純度が９８質量％以上となる銀合金ボンディングワイヤ（以下、高純度銀合金ワイヤと記す）を用いてボール圧縮部６を形成すると、接合界面近傍の銀濃度が高くなり、腐食されやすい銀とアルミニウムとの金属間化合物（銀とアルミニウムの比率が３対１となるＡｇ３Ａｌ等）が形成されやすくなる。高純度銀合金ワイヤには金やパラジウムのような貴金属等が最大で２質量％含まれるものの、Ａｇ３Ａｌのような耐食性の低い銀とアルミニウムとの金属間化合物が生成されるため、モールド樹脂に含まれる塩素（Ｃｌ）等のハロゲンやモールド樹脂に吸湿された水分によって金属間化合物が腐食され、電極２とボール圧縮部６との間に通電不良が生じやすくなる。これに対して、接合界面近傍における金濃度を高めて、銀の純度を相対的に低下させることにより、Ａｇ３Ａｌ金属間化合物が抑制されることにより、銀とアルミニウムの比率が２対１となるＡｇ２Ａｌ金属間化合物が生成されやすくなる。Ａｇ２Ａｌ金属間化合物は、Ａｇ３Ａｌ金属間化合物に比べて耐食性に優れていることから、電極２とボール圧縮部６との接合信頼性を向上させることができる。加えて、金濃化接合領域７に存在する金が過酷な環境下における経時変化、例えば、銀のマイグレーションや拡散等に対してバリアー的な役割を果たし、耐食性のあるＡｇ２Ａｌ金属間化合物を維持することができる。さらに、金はアルミニウムと、より耐食性に優れた金とアルミニウムの金属間化合物（例えばＡｕ４Ａｌ金属間化合物）が生成されると考えられ、より一層の接合信頼性の向上に寄与していると推察される。このように、電極２とボール圧縮部６との接合界面近傍に金濃化接合領域７を形成することによって、特に自動車等の高温多湿の過酷な環境下で使用される半導体装置の信頼性を高めことができる。 By providing a gold-enriched bonding region 7 having a gold concentration of 5 atomic% or more with respect to the total amount of gold, silver, and aluminum in the vicinity of the bonding interface, the gold concentration in the vicinity of the bonding interface is increased and the silver concentration is relatively increased. It can be kept low. Therefore, it is possible to improve the joint reliability between the electrode 2 and the ball compression unit 6. That is, when the ball compression portion 6 is formed using a silver alloy bonding wire having a silver purity of 98% by mass or more (hereinafter referred to as a high-purity silver alloy wire), the silver concentration in the vicinity of the bonding interface becomes high and is easily corroded. An intermetallic compound of silver and aluminum (such as Ag 3 Al having a ratio of silver and aluminum of 3: 1) is likely to be formed. Although the high-purity silver-alloy wire precious metals such as gold and palladium contained 2 wt% at the maximum, since the intermetallic compound of the corrosion resistance of low silver and aluminum, such as Ag 3 Al is produced, the molding resin The metal-metal compound is corroded by the halogen such as chlorine (Cl) contained in the metal and the moisture absorbed by the mold resin, and a poor energization is likely to occur between the electrode 2 and the ball compression unit 6. On the other hand, by increasing the gold concentration near the bonding interface and relatively lowering the purity of silver, the Ag 3 Al intermetallic compound is suppressed, so that the ratio of silver to aluminum is 2: 1. Ag 2 Al intermetallic compound is likely to be produced. Since the Ag 2 Al intermetallic compound is superior in corrosion resistance to the Ag 3 Al intermetallic compound, the bonding reliability between the electrode 2 and the ball compression portion 6 can be improved. In addition, the gold present in the gold-enriched bonding region 7 acts as a barrier against changes over time in a harsh environment, such as silver migration and diffusion, and provides a corrosion-resistant Ag 2 Al intermetallic compound. Can be maintained. Furthermore, it is considered that gold produces aluminum and an intermetallic compound of gold and aluminum having better corrosion resistance (for example, an Au 4 Al intermetallic compound), which contributes to further improvement of bonding reliability. Inferred. By forming the gold-enriched bonding region 7 in the vicinity of the bonding interface between the electrode 2 and the ball compression portion 6 in this way, the reliability of the semiconductor device used in a harsh environment of high temperature and humidity such as an automobile can be improved. Can be raised.
　電極２とボール圧縮部６との接合界面近傍に形成される金濃化接合領域７において、金濃度は金と銀とアルミニウムの合計量に対して５原子％以上とする。金濃化接合領域７における金の濃度が金と銀とアルミニウムの合計量に対して５原子％未満であると、金による腐食（硫化や酸化）を抑制する効果を十分に得ることができないと共に、相対的に銀濃度が増加するため、Ａｇ３Ａｌ金属間化合物が形成されやすくなり、電極２とボール圧縮部６との接合信頼性が低下する。金濃化接合領域７における金と銀とアルミニウムの合計量に対する金濃度は５原子％以上がより好ましく、さらに１０原子％以上が望ましい。銀芯材４の直径に対する被覆層５の厚さの比により決定されるものである。 In the gold-enriched bonding region 7 formed near the bonding interface between the electrode 2 and the ball compression portion 6, the gold concentration is 5 atomic% or more with respect to the total amount of gold, silver, and aluminum. If the concentration of gold in the gold-enriched bonding region 7 is less than 5 atomic% with respect to the total amount of gold, silver and aluminum, the effect of suppressing corrosion (sulfurization and oxidation) by gold cannot be sufficiently obtained. Since the silver concentration is relatively increased, the Ag 3 Al metal-metal compound is likely to be formed, and the bonding reliability between the electrode 2 and the ball compression portion 6 is lowered. The gold concentration in the gold-enriched bonding region 7 with respect to the total amount of gold, silver and aluminum is more preferably 5 atomic% or more, and further preferably 10 atomic% or more. It is determined by the ratio of the thickness of the coating layer 5 to the diameter of the silver core material 4.
　上述した金濃化接合領域７は、さらにパラジウム（Ｐｄ）、白金（Ｐｔ）、ゲルマニウム（Ｇｅ）、インジウム（Ｉｎ）、銅（Ｃｕ）、及びニッケル（Ｎｉ）から選ばれる少なくとも１つ元素（以下、Ｍ元素と呼び）を含んでいることが好ましい。金濃化接合領域７が上記したようなＭ元素を含むことによって、電極２とボール圧縮部６との接合信頼性をさらに向上させることができる。Ｍ元素は、例えば銀芯材４に含有させておくことができる。Ｍ元素はその含有量がワイヤ全体に対して０．２原子％以上２．０原子％以下となるように含まれることが好ましい。０．２原子％未満であると、Ｍ元素による接合信頼性のさらなる向上効果を十分に得ることができず、また２．０原子％を超えると銀芯材４の比抵抗を上昇させるおそれがある。 The gold-concentrated bonding region 7 described above further comprises at least one element selected from palladium (Pd), platinum (Pt), germanium (Ge), indium (In), copper (Cu), and nickel (Ni) (hereinafter,). , M element) is preferably contained. By including the M element as described above in the gold-enriched bonding region 7, the bonding reliability between the electrode 2 and the ball compression unit 6 can be further improved. The M element can be contained in, for example, the silver core material 4. The M element is preferably contained so that its content is 0.2 atomic% or more and 2.0 atomic% or less with respect to the entire wire. If it is less than 0.2 atomic%, the effect of further improving the bonding reliability by the M element cannot be sufficiently obtained, and if it exceeds 2.0 atomic%, the specific resistance of the silver core material 4 may be increased. is there.
　金濃化接合領域の分析方法を、接合対象としてアルミニウム電極を採用した場合を例に、詳細に説明する。アルミニウムとアルミニウム以外の元素を含む電極を用いる場合も同様である。金被覆銀ボンディングワイヤを用いてフリーエアーボールを形成し、アルミニウム電極上にボールボンディングする。アルミニウム電極に接合されたボール圧縮部をワイヤ長手方向の中心線に平行な面が露出するように切断する。この切断面を、ワイヤ側の所定箇所から接合面に略垂直方向（深さ方向）にライン分析する。ライン分析としては、電解放出形走査型電子顕微鏡／エネルギー分散型Ｘ線分光分析（ＦＥ－ＳＥＭ／ＥＤＸ）が好適である。なお、当該分析に係る切断面はワイヤ長手方向の中心線を含むか、中心線にできるだけ近づけるように形成することが好ましい。 The analysis method of the gold-enriched bonding region will be described in detail by taking as an example the case where an aluminum electrode is used as the bonding target. The same applies when an electrode containing aluminum and an element other than aluminum is used. Free air balls are formed using gold-coated silver bonding wires and ball-bonded onto aluminum electrodes. The ball compression portion joined to the aluminum electrode is cut so that the surface parallel to the center line in the longitudinal direction of the wire is exposed. This cut surface is line-analyzed from a predetermined position on the wire side in a direction substantially perpendicular to the joint surface (depth direction). As the line analysis, a field emission scanning electron microscope / energy dispersive X-ray spectroscopic analysis (FE-SEM / EDX) is suitable. It is preferable that the cut surface according to the analysis includes the center line in the longitudinal direction of the wire or is formed so as to be as close to the center line as possible.
　ボール接合部の切断面は次のようにして作製することができる。リードフレームとして、例えばＰＢＧＡ３２ＰＩＮフレームを用い、このフレーム中央部に略正方形の半導体チップを接合する。半導体チップ上のアルミニウム電極とフレーム上の外部電極を、金被覆銀ボンディングワイヤによってワイボンディングして測定サンプルを作製する。この半導体チップ上にあるアルミニウム電極に金被覆銀ボンディングワイヤワイヤをボール接合（第１接合）し、リードフレームにウェッジ接合（第２接合）する。通常チップには、多くの電極が複数列に列設されているので、例えばそのうちの一列（４個）の電極にボンディングワイヤを等間隔で接合し、他の３列（３辺）も同様に接合する。合計で１６個のアルミニウム電極にボール接合する。リードフレームへのウェッジ接合を含めると合計で３２組のワイヤボンディングとなる。 The cut surface of the ball joint can be made as follows. For example, a PBGA32PIN frame is used as the lead frame, and a substantially square semiconductor chip is bonded to the central portion of the frame. The aluminum electrode on the semiconductor chip and the external electrode on the frame are wire-bonded with a gold-coated silver bonding wire to prepare a measurement sample. A gold-coated silver bonding wire is ball-bonded (first bonding) to an aluminum electrode on the semiconductor chip, and wedge-bonded (second bonding) to a lead frame. Since many electrodes are usually arranged in multiple rows on a chip, for example, bonding wires are bonded to one row (4) of electrodes at equal intervals, and the other 3 rows (3 sides) are similarly bonded. Join. A total of 16 aluminum electrodes are ball-bonded. Including wedge bonding to the lead frame, there are a total of 32 sets of wire bonding.
　フリーエアーボールの形成条件は、例えば、金被覆銀ボンディングワイヤの線径が１０～３０μｍである場合に、放電電流値が３０～９０ｍＡ、フリーエアーボール径がワイヤ線径の１．５～２．３倍となるようにアーク放電条件を設定する。ボンダー装置は、例えば、ケー・アンド・エス社製のボンダー装置（全自動ボンダー：ＩＣｏｎｎ　ＰｒｏＣｕ　ＰＬＵＳ）等の市販品を使用することができる。当該ボンダー装置を使用する場合、装置の設定として放電時間が５０～１０００μｓ、ＥＦＯ－Ｇａｐが２５～４５ｍｉｌ（約６３５～１１４３μｍ）、テール長さが６～１２ｍｉｌ（約１５２～３０５μｍ）であることが好ましい。当該ボンダー装置以外のその他のボンダー装置を用いる場合、上記と同等の条件、例えばフリーエアーボール径が上記と同等の大きさになる条件であればよい。 The conditions for forming the free air ball are, for example, when the wire diameter of the gold-coated silver bonding wire is 10 to 30 μm, the discharge current value is 30 to 90 mA, and the free air ball diameter is 1.5 to 2. Set the arc discharge conditions so that they are tripled. As the bonder device, for example, a commercially available product such as a bonder device (fully automatic bonder: IConn ProCu PLUS) manufactured by K & S Co., Ltd. can be used. When using the bonder device, the device settings are that the discharge time is 50 to 1000 μs, the EFO-Gap is 25 to 45 mil (about 635 to 1143 μm), and the tail length is 6 to 12 mil (about 152 to 305 μm). preferable. When a bonder device other than the bonder device is used, the conditions may be the same as above, for example, the free air ball diameter may be the same as the above.
　また、ボール接合条件（第１接合の条件）は、例えばワイヤ線径φが２０μｍでボール径が３６μｍのフリーエアーボールを形成したものについては、ボール圧縮部のくびれ部から接合界面側の高さが略１０μｍ、接合面に略平行方向の最大幅が略４５μｍとなるように、また、ボールシェア強度が１５ｇｆ以上となるようにボンダー装置にて調節することができる。また、第２接合の条件は、例えば、圧着力６０ｇｆ、超音波出力９０ｍＡｍｐｓ、超音波出力時間１５ｍｓである。なお、第１接合部から第２接合部までのループ長さは２．０ｍｍにてボンディングすることができる。 The ball joining condition (first joining condition) is, for example, for a free air ball having a wire wire diameter of 20 μm and a ball diameter of 36 μm, the height from the constricted portion of the ball compression portion to the junction interface side. Can be adjusted by a bonder device so that the maximum width in the direction substantially parallel to the joint surface is approximately 45 μm, and the ball share strength is approximately 15 gf or more. The conditions for the second joining are, for example, a crimping force of 60 gf, an ultrasonic output of 90 mAmps, and an ultrasonic output time of 15 ms. The loop length from the first joint to the second joint can be set to 2.0 mm.
　次に、上記で形成された合計１６組の接合部を含む半導体チップを封止樹脂によってモールド機でモールドする。モールドが固まったらモールドした部分をフレームからカットし、さらに、モールド部分の中にあるボール接合部の一列（一辺）の近傍を切断する。切断したモールドは円筒状の型（かた）にボール接合部の断面が研磨できる方向に置き、埋め込み樹脂を流し込み硬化剤を添加して硬化させる。そのあと、この半導体チップ入の硬化させた円筒状の樹脂をなるべくボール接合部の中心付近が露出するように研磨器にて粗研磨する。おおよそボール接合部の中心断面近くまで研磨したら、最終研磨仕上げおよびボール中心部を含む面（ワイヤ部の中心線を通り、中心線に平行な面）がちょうど露出して分析面の位置になるようにイオンミリング装置にて微調整する。ワイヤ部断面のワイヤ幅がワイヤ直径の長さになれば切断面がボール中心部を含む面になっている目安となる。切断面を分析する面として、その所望の箇所を、ＦＥ－ＳＥＭ／ＥＤＸによって、ボール側から電極側に向けてライン分析する。ライン分析条件は、例えば、加速電圧６ｋｅＶ、測定領域φ０．１８μｍ、測定間隔０．０２μｍである。 Next, the semiconductor chip containing a total of 16 sets of joints formed above is molded with a sealing resin by a molding machine. When the mold has hardened, the molded part is cut from the frame, and further, the vicinity of one row (one side) of the ball joint in the mold part is cut. The cut mold is placed in a cylindrical mold in a direction in which the cross section of the ball joint can be polished, and the embedded resin is poured and a curing agent is added to cure the cut mold. After that, the cured cylindrical resin containing the semiconductor chip is roughly polished with a polishing machine so that the vicinity of the center of the ball joint is exposed as much as possible. After polishing to approximately the center cross section of the ball joint, the final polishing finish and the surface including the center of the ball (the surface that passes through the center line of the wire and is parallel to the center line) is just exposed and is at the position of the analysis surface. Make fine adjustments with an ion milling device. If the wire width of the cross section of the wire portion becomes the length of the wire diameter, it is a guide that the cut surface is the surface including the ball center portion. As the surface to be analyzed, the desired portion is line-analyzed from the ball side to the electrode side by FE-SEM / EDX. The line analysis conditions are, for example, an acceleration voltage of 6 keV, a measurement area of φ0.18 μm, and a measurement interval of 0.02 μm.
　金濃化接合領域７の有無を定量的に測定するには、上記した測定試料の分析面（研磨断面）において、ボール圧縮部６側から接合界面を介して電極２側に向けて、電界放出型走査電子顕微鏡（ＦＥ－ＳＥＭ：Ｆｉｅｌｄ　Ｅｍｉｓｓｉｏｎ－Ｓｃａｎｎｉｎｇ　Ｅｌｅｃｔｒｏｎ　Ｍｉｃｒｏｓｃｏｐｅ）付属のエネルギー分散型Ｘ線分析（ＥＤＸ：Ｅｎｅｒｇｙ　Ｄｉｓｐｅｒｓｉｖｅ　Ｘ－ｒａｙ　Ｓｐｅｃｔｒｏｍｅｔｒｙ）によりライン分析することで金濃化接合領域７を確認できる。ライン分析条件は、日立ハイテクノロジーズ社製のＦＥ－ＳＥＭ　ＳＵ８２２０とブルカー社製のＸＦｌａｓｈ（Ｒ）５０６０ＦＱを用いて、加速電圧６ｋｅＶ、測定長さ２μｍ、測定間隔０．０３μｍ、測定時間６０秒とする。ライン分析の濃度プロファイルにて、金濃度が銀と金及びアルミニウムの合計量に対して５原子％以上の箇所が存在していれば、金濃化接合領域７が形成されていると判断できる。 In order to quantitatively measure the presence or absence of the gold-enriched bonding region 7, field emission is performed from the ball compression portion 6 side toward the electrode 2 side via the bonding interface on the analysis surface (polished cross section) of the measurement sample described above. The gold-enriched junction region 7 can be confirmed by line analysis by energy dispersive X-ray analysis (EDX: Energy Dispersive X-ray Samplery) attached to a type scanning electron microscope (FE-SEM: Field Emission-Scanning Electron Microscope). The line analysis conditions are an acceleration voltage of 6 keV, a measurement length of 2 μm, a measurement interval of 0.03 μm, and a measurement time of 60 seconds using FE-SEM SU8220 manufactured by Hitachi High-Technologies Corporation and XFlash (R) 5060FQ manufactured by Bruker Corporation. .. In the concentration profile of the line analysis, if the gold concentration is 5 atomic% or more with respect to the total amount of silver, gold and aluminum, it can be determined that the gold-enriched bonding region 7 is formed.
　金濃化接合領域は、フリーエアーボールと電極とが接触して接合された接合面近傍、すなわち、アルミニウムと銀と金が共存する領域において、金、銀、及びアルミニウムの合計に対する金の割合が５．０原子％以上、好ましくは１０．０原子％以上となる所定の範囲として評価することができる。具体的には、上記ボール接合部の断面の所定の箇所を、ボール接合部の任意の面からアルミニウム電極の面に向けてワイヤ長手方向に平行にＦＥ－ＳＥＭ／ＥＤＸによってライン分析したときに、アルミニウムが５．０原子％を超え９５．０原子％以下の範囲内の各測定点で、金、銀、及びアルミニウムの合計に対する金の割合が５．０原子％以上、好ましくは１０．０原子％以上となる所定の範囲を金濃化接合領域として評価することができる。ここで、アルミニウム濃度が５．０原子％を超え９５．０原子％以下の範囲で測定する理由は、分析におけるノイズ等の影響でアルミニウムが存在しない箇所の分析値が０原子％にならないことや、アルミニウムのみの箇所の分析値が１００原子％にならないことがあるからである。 In the gold-enriched bonding region, the ratio of gold to the total of gold, silver, and aluminum is in the vicinity of the bonding surface where the free air ball and the electrode are contacted and bonded, that is, in the region where aluminum, silver, and gold coexist. It can be evaluated as a predetermined range of 5.0 atomic% or more, preferably 10.0 atomic% or more. Specifically, when a predetermined portion of the cross section of the ball joint is line-analyzed by FE-SEM / EDX parallel to the wire longitudinal direction from an arbitrary surface of the ball joint toward the surface of the aluminum electrode, At each measurement point within the range of more than 5.0 atomic% and 95.0 atomic% or less of aluminum, the ratio of gold to the total of gold, silver, and aluminum is 5.0 atomic% or more, preferably 10.0 atoms. A predetermined range of% or more can be evaluated as a gold-enriched bonding region. Here, the reason why the aluminum concentration is measured in the range of more than 5.0 atomic% and 95.0 atomic% or less is that the analytical value of the place where aluminum does not exist does not become 0 atomic% due to the influence of noise in the analysis. This is because the analytical value of the aluminum-only portion may not be 100 atomic%.
　図２はＥＤＸによるライン分析結果の一例を示している。図２において、縦軸は各元素の濃度（原子％）であり、横軸は測定試料における測定距離（μｍ）である。図２の横軸の測定距離が約２．２μｍの箇所から約２．６μｍの箇所までが接合界面近傍の領域となり、そのような領域に金濃度が５．０原子％以上の領域、すなわち金接合濃化領域が存在している。ここでは金のピーク濃度が約１５．０原子％を示している。従って、図２に示す濃度プロファイルを有するワイヤ接合構造１は、電極２とボール圧縮部６との接合界面近傍に金濃化接合領域７が存在していると判断することができる。また、図２において接合界面近傍に金濃度が低い領域（横軸２．４μｍ付近）があるが、その付近の銀とアルミニウムの濃度比から耐食性の強いＡｇ２Ａｌ金属間化合物が生成されていると推測される。 FIG. 2 shows an example of the line analysis result by EDX. In FIG. 2, the vertical axis represents the concentration (atomic%) of each element, and the horizontal axis represents the measurement distance (μm) in the measurement sample. The region from the measurement distance of about 2.2 μm to about 2.6 μm on the horizontal axis of FIG. 2 is the region near the bonding interface, and the region where the gold concentration is 5.0 atomic% or more, that is, gold There is a junction thickening region. Here, the peak concentration of gold shows about 15.0 atomic%. Therefore, in the wire bonding structure 1 having the concentration profile shown in FIG. 2, it can be determined that the gold-concentrated bonding region 7 exists in the vicinity of the bonding interface between the electrode 2 and the ball compression unit 6. Further, in FIG. 2, there is a region where the gold concentration is low (around 2.4 μm on the horizontal axis) near the bonding interface, but an Ag 2 Al intermetallic compound having strong corrosion resistance is generated from the concentration ratio of silver and aluminum in the vicinity. It is presumed.
　上述した金濃化接合領域７の形成範囲は、電極２とボール圧縮部６との接合界面の全域であることが好ましいが、それに限られるものではない。すなわち、金濃化接合領域７は電極２とボール圧縮部６との接合信頼性を高める上で、図３に示すように、ボール圧縮部６の最大幅Ｙに対して、金濃化接合領域７が少なくともボール圧縮部６の両外周部から１／８の位置（線Ｘ１及び線Ｘ２で示す）までの間にそれぞれ形成されていればよい。ここで、ボール圧縮部６の最大幅Ｙとは、図３に示す電極２とボール圧縮部６との接合構造をワイヤ３の長手方向に切断した断面図において、長手方向に直交する水平方向におけるボール圧縮部６の両最外端部（線Ｘで示す）間の幅を示す。このような両最外端部（線Ｘ）から、ボール圧縮部６の最大幅（線Ｙ）を８等分したうちの両最外端部から１／８の位置（線Ｘ１及び線Ｘ２）までの間に、少なくとも金濃化接合領域７が形成されていればよい。このような位置に金濃化接合領域７を形成することによって、接合界面に侵入する大気や水分等による電極２とボール圧縮部６との接合信頼性の低下を抑制することができる。なぜなら、封止樹脂等からのハロゲン元素や水分は、ボール接合面近傍の両端、すなわち、ボールと電極の接合部の際付近のわずかな隙間等から浸入してくる可能性が高いため、両端付近に耐腐食性の高い金濃化接合領域があることがハロゲン等の浸入を阻止するという意味で非常に重要な役割を果たすからである。 The formation range of the gold-enriched bonding region 7 described above is preferably, but not limited to, the entire area of the bonding interface between the electrode 2 and the ball compression portion 6. That is, as shown in FIG. 3, the gold-enriched bonding region 7 has a gold-enriched bonding region with respect to the maximum width Y of the ball compression unit 6 in order to improve the bonding reliability between the electrode 2 and the ball compression unit 6. 7 may be formed at least between both outer peripheral portions of the ball compression portion 6 and the position of 1/8 (indicated by the line X1 and the line X2). Here, the maximum width Y of the ball compression portion 6 is a cross-sectional view obtained by cutting the joint structure between the electrode 2 and the ball compression portion 6 shown in FIG. 3 in the longitudinal direction of the wire 3 in the horizontal direction orthogonal to the longitudinal direction. The width between both outermost ends (indicated by the line X) of the ball compression portion 6 is shown. The maximum width (line Y) of the ball compression portion 6 is divided into eight equal parts from both outermost ends (line X), and the position is 1/8 from both outermost ends (line X1 and line X2). It suffices that at least the gold-enriched bonding region 7 is formed in the meantime. By forming the gold-enriched bonding region 7 at such a position, it is possible to suppress a decrease in bonding reliability between the electrode 2 and the ball compression portion 6 due to air, moisture, or the like entering the bonding interface. This is because there is a high possibility that halogen elements and moisture from the sealing resin or the like will infiltrate from both ends near the ball joint surface, that is, from a slight gap near the joint between the ball and the electrode. This is because the presence of a gold-concentrated junction region with high corrosion resistance plays a very important role in preventing the infiltration of halogens and the like.
　さらに、発明者らが鋭意研究した結果、金濃化接合領域７の形成範囲は、上記したボール圧縮部６の最大幅Ｙに対して、占有率が合計で２５％以上となるように形成されていることが好ましいことが分かった。ここで言う金濃化接合領域７の占有率とは、図３に示す電極２とボール圧縮部６との接合構造の断面図において、金濃化接合領域７の形成領域を分析した際に、ボール圧縮部６の最大幅Ｙに対して金濃化接合領域７の形成領域が２５％以上であることを意味する。このように、ボール圧縮部６の最大幅Ｙに対して金濃化接合領域７の占有率が少なくとも２５％となるように形成することによって、接合界面に侵入する大気や水分等による電極２とボール圧縮部６との接合信頼性の低下を抑制することができる。なお、ボール圧縮部６の最大幅Ｙに対する金濃化接合領域７の占有率は少なくとも２５％であればよいが、さらに４０％以上であることがより好ましく、５０％以上であることがさらに好ましい。 Further, as a result of diligent research by the inventors, the formation range of the gold-enriched joint region 7 is formed so that the total occupancy rate is 25% or more with respect to the maximum width Y of the ball compression portion 6 described above. It turned out that it is preferable. The occupancy rate of the gold-enriched joint region 7 referred to here is the occupancy rate of the gold-enriched joint region 7 when the formation region of the gold-enriched joint region 7 is analyzed in the cross-sectional view of the joint structure between the electrode 2 and the ball compression portion 6 shown in FIG. This means that the formation region of the gold-concentrated joint region 7 is 25% or more with respect to the maximum width Y of the ball compression portion 6. In this way, by forming the gold-enriched bonding region 7 so that the occupancy rate of the gold-concentrated bonding region 7 is at least 25% with respect to the maximum width Y of the ball compression portion 6, the electrode 2 is formed by air, moisture, or the like invading the bonding interface. It is possible to suppress a decrease in bonding reliability with the ball compression unit 6. The occupancy rate of the gold-enriched bonding region 7 with respect to the maximum width Y of the ball compression unit 6 may be at least 25%, more preferably 40% or more, and further preferably 50% or more. ..
　金濃化接合領域の測定方法について説明する。例えば、ＥＰＭＡ測定（面分析）では、通常、測定対象の元素の存在率を、測定対象に電子線を照射したときに当該元素から発せられるＸ線強度として測定し、その強度をＥＰＭＡ画像上で色彩に反映させたカラーマッピングで表示するのが一般的である。つまり、測定対象の元素が存在しない点は真っ黒に表示され、元素の存在確率が高い順に一例として「白、赤、黄、緑、青、黒」等のグラデーションで表示される。このようなＥＰＭＡ画像の接合面近傍において、最も金強度が小さい点、すなわち、ＥＰＭＡ画像上に真っ黒ではないが金による強度が観測される箇所のなかで一番暗い箇所（黒に近い青色の箇所）において、金濃度が５．０原子％以上あれば、それ以外に表示される上記の箇所よりも強度の強い色彩で表示される領域を金濃化接合領域として特定することができる。また、ライン分析とＥＰＭＡ画像（面分析）の結果を重ね合わせて、ライン分析で金濃度が５．０原子％あるいはこれ以上に観測された、ＥＰＭＡ上の測定点と強度が同等かそれ以上の箇所を、強度差（画像上での色彩）として識別できる設定にするか、目視で判定する。これにより、金濃化接合領域の有無および占有率が算出できる。なお、金濃化接合領域の占有率を算出する場合において、ＥＰＭＡのカラーマッピング画像を用いるが、画像を拡大すればするほど金濃化接合領域が「疎」な状態に見えてしまうことがあるので、少なくともボール圧縮部が１枚の画像（枠）に収まる程度の倍率で占有率を算出するのが好ましい。 The method of measuring the gold-enriched joint region will be explained. For example, in EPMA measurement (plane analysis), the abundance of an element to be measured is usually measured as the X-ray intensity emitted from the element when the measurement target is irradiated with an electron beam, and the intensity is measured on an EPMA image. It is common to display with color mapping reflected in the color. That is, the points where the element to be measured does not exist are displayed in black, and are displayed in gradations such as "white, red, yellow, green, blue, and black" as an example in descending order of the existence probability of the elements. In the vicinity of the joint surface of such an EPMA image, the point with the lowest gold intensity, that is, the darkest point (blue part close to black) among the places on the EPMA image where the strength due to gold is observed although it is not black. ), If the gold concentration is 5.0 atomic% or more, the region displayed in a color stronger than the above-mentioned portion displayed other than the above can be specified as the gold-enriched junction region. In addition, by superimposing the results of the line analysis and the EPMA image (plane analysis), the gold concentration observed in the line analysis was 5.0 atomic% or more, and the intensity was equal to or higher than the measurement point on the EPMA. Whether the location is set so that it can be identified as an intensity difference (color on the image) is visually determined. This makes it possible to calculate the presence / absence and occupancy of the gold-enriched joint region. When calculating the occupancy rate of the gold-enriched joint region, the EPMA color mapping image is used, but the larger the image, the more the gold-enriched joint region may appear to be in a “sparse” state. Therefore, it is preferable to calculate the occupancy rate at a magnification that allows at least the ball compression portion to fit in one image (frame).
　実施形態のワイヤ接合構造１において、銀を主成分とする芯材（銀芯材）４は、ボンディングワイヤ３を主として構成するものであり、ボンディングワイヤ３の機能を担うものである。このような芯材４は、純銀により構成することが好ましいが、場合によっては銀に添加元素を加えた銀合金により構成してもよい。ただし、銀ボンディングワイヤとしての機能を損なわないように、芯材４は銀を主成分として含むものとする。ここで、銀を主成分として含むとは、芯材４が少なくとも５０質量％以上の銀を含むことを意味する。芯材４を銀合金で構成する場合、パラジウム（Ｐｄ）、白金（Ｐｔ）、リン（Ｐ）、金（Ａｕ）、ニッケル（Ｎｉ）、銅（Ｃｕ）、鉄（Ｆｅ）、カルシウム（Ｃａ）、ロジウム（Ｒｈ）、ゲルマニウム（Ｇｅ）、ガリウム（Ｇａ）及びインジウム（Ｉｎ）から選ばれる少なくとも１つ以上の元素を含む銀合金を適用することが好ましいが、これらに限定されるものではない。 In the wire bonding structure 1 of the embodiment, the core material (silver core material) 4 containing silver as a main component mainly constitutes the bonding wire 3 and bears the function of the bonding wire 3. Such a core material 4 is preferably made of sterling silver, but in some cases, it may be made of a silver alloy in which an additive element is added to silver. However, the core material 4 contains silver as a main component so as not to impair the function as a silver bonding wire. Here, the fact that silver is contained as a main component means that the core material 4 contains at least 50% by mass or more of silver. When the core material 4 is composed of a silver alloy, palladium (Pd), platinum (Pt), phosphorus (P), gold (Au), nickel (Ni), copper (Cu), iron (Fe), calcium (Ca). , A silver alloy containing at least one element selected from rhodium (Rh), germanium (Ge), gallium (Ga) and indium (In) is preferably applied, but is not limited thereto.
　芯材４を構成する銀合金における添加元素は、電極との接合性や接合信頼性、機械的強度の向上等に効果を示す。ただし、添加元素の含有量が多すぎると芯材４の比抵抗が増加し、銀ボンディングワイヤとしての機能が低下するおそれがある。このため、金被覆銀ボンディングワイヤ３は金ワイヤ（純度９９．９９質量％（４Ｎ））の比抵抗以下、例えば２．３μΩ・ｃｍ以下の範囲となるように添加元素の含有量を設定することが好ましい。純銀及び銀合金のいずれで芯材４を構成する場合においても、不可避な不純物を含んでいてもよいが、金被覆銀ボンディングワイヤ３の比抵抗が２．３μΩ・ｃｍ以下の範囲となる不純物量であることが好ましい。このような銀芯材４を適用することによって、ボンディングワイヤ３に求められる比抵抗の値を満足させることができる。金よりも比抵抗の低い銀が多く含有している銀合金のほうが比抵抗は低いと考えられがちであるが、純金（４Ｎ）よりも銀合金の方が合金化によって比抵抗が高くなることが多い。なお、ワイヤの比抵抗は四端子法で測定することが好ましく、例えば、ミリオームメーター（横河ヒューレット・パッカード株式会社製　型番４３２８Ａ）等を用いて測定する。 The additive element in the silver alloy constituting the core material 4 is effective in improving the bondability with the electrode, the bond reliability, the mechanical strength, and the like. However, if the content of the additive element is too large, the specific resistance of the core material 4 may increase and the function as a silver bonding wire may deteriorate. Therefore, the content of the additive element of the gold-coated silver bonding wire 3 is set so as to be within the specific resistance of the gold wire (purity 99.99% by mass (4N)), for example, 2.3 μΩ · cm or less. Is preferable. When the core material 4 is made of either sterling silver or a silver alloy, it may contain unavoidable impurities, but the amount of impurities in which the specific resistance of the gold-coated silver bonding wire 3 is in the range of 2.3 μΩ · cm or less. Is preferable. By applying such a silver core material 4, the value of specific resistance required for the bonding wire 3 can be satisfied. It is often thought that a silver alloy containing more silver, which has a lower resistivity than gold, has a lower resistivity, but a silver alloy has a higher resistivity due to alloying than pure gold (4N). There are many. The specific resistance of the wire is preferably measured by the four-terminal method, and is measured using, for example, a milliohm meter (Yokogawa Hewlett-Packard Co., Ltd., model number 4328A) or the like.
　実施形態の金被覆銀ボンディングワイヤ３において、被覆層５は金を主成分として含んでいる。ここで、金を主成分として含むとは、被覆層５が５０質量％以上の金を含むことを意味する。被覆層５における金含有量は、多ければ多いほどよく、少なくとも金が被覆層５中に５０質量％以上含まれていればよく、さらに金含有量は８０％質量以上が好ましく、９９質量％以上がより好ましい。被覆層５の金含有量は、ボンディングワイヤ３の表面からオージェ電子分光（ＡＥＳ：Ａｕｇｅｒ　Ｅｌｅｃｔｒｏｎ　Ｓｐｅｃｔｒｏｓｃｏｐｙ）等によるワイヤ最表面の定量分析にて測定できる。なお、ここでいう金含有量は、検出される金属元素の合計量に対する値であり、表面に吸着等で存在している炭素や酸素等は含めない。 In the gold-coated silver bonding wire 3 of the embodiment, the coating layer 5 contains gold as a main component. Here, the inclusion of gold as a main component means that the coating layer 5 contains 50% by mass or more of gold. The higher the gold content in the coating layer 5, the better, at least 50% by mass or more of gold may be contained in the coating layer 5, and the gold content is preferably 80% by mass or more, preferably 99% by mass or more. Is more preferable. The gold content of the coating layer 5 can be measured from the surface of the bonding wire 3 by quantitative analysis of the outermost surface of the wire by Auger electron spectroscopy (AES) or the like. The gold content referred to here is a value with respect to the total amount of detected metal elements, and does not include carbon, oxygen, etc. existing on the surface due to adsorption or the like.
　上述した金被覆銀ボンディングワイヤ３は、１３μｍ以上３０μｍ以下の線径を有することが好ましい。ワイヤ３の線径が１３μｍ未満であると、半導体装置の製造時にボンディングワイヤ３を用いてワイヤボンディングを行った際に、強度や導電性等が低下してワイヤボンディングの信頼性等が低下するおそれがある。ワイヤ３の線径が３０μｍを超えると、ボンディング本数が稼げないことと、隣接するボンディングワイヤとの接触（ショート）する可能性が高くなる。 The gold-coated silver bonding wire 3 described above preferably has a wire diameter of 13 μm or more and 30 μm or less. If the wire diameter of the wire 3 is less than 13 μm, when wire bonding is performed using the bonding wire 3 at the time of manufacturing a semiconductor device, the strength, conductivity, etc. may decrease, and the reliability of wire bonding may decrease. There is. If the wire diameter of the wire 3 exceeds 30 μm, the number of bonding wires cannot be increased and the possibility of contact (short circuit) with the adjacent bonding wire increases.
　上記した線径を有する金被覆銀ボンディングワイヤ３において、線径に応じて被覆層５の厚さは５０ｎｍ以上２６０ｎｍ以下であることが好ましい。被覆層５の厚さは、金を主成分とする領域のワイヤ３の表面から垂直方向に対して芯材４に向かう深さ方向の厚さを示すものである。被覆層５の厚さが５０ｎｍ未満であると、金被覆銀ボンディングワイヤ３と電極２との接合信頼性を、金を主成分とする被覆層５により十分に高めることができないおそれがある。被覆層５の厚さが２６０ｎｍを超えると、被覆層５の形成性が低下するおそれがある。なお、被覆層５の厚さは金被覆銀ボンディングワイヤ３の線径に応じて設定することが好ましい。 In the gold-coated silver bonding wire 3 having the above-mentioned wire diameter, the thickness of the coating layer 5 is preferably 50 nm or more and 260 nm or less depending on the wire diameter. The thickness of the coating layer 5 indicates the thickness in the depth direction from the surface of the wire 3 in the region containing gold as a main component toward the core material 4 in the vertical direction. If the thickness of the coating layer 5 is less than 50 nm, the bonding reliability between the gold-coated silver bonding wire 3 and the electrode 2 may not be sufficiently enhanced by the coating layer 5 containing gold as a main component. If the thickness of the coating layer 5 exceeds 260 nm, the formability of the coating layer 5 may decrease. The thickness of the coating layer 5 is preferably set according to the wire diameter of the gold-coated silver bonding wire 3.
　被覆層５の厚さは、以下のようにして測定するものとする。すなわち、金被覆銀ボンディングワイヤ３において、その表面からＡＥＳにより深さ方向に元素濃度分析を実施して、表面近傍に存在する金の含有量の最大値を１００％としたときの５０％に位置する箇所を境界部とし、その境界部から表面までの領域を被覆層５の厚さとして求める。金被覆銀ボンディングワイヤ３の表面から深さ方向への元素分布は、ＡＥＳ分析によって測定することができる。例えば、ワイヤ１の表面から銀芯材４に向かって被覆層５の各元素濃度を分析する手段として、ＡＥＳ分析による濃度測定が有効である。ここでは一例として日本電子製のオージェ電子分光装置（商品名：ＪＡＭＰ－９５００Ｆ）を用いて、一次電子線の加速電圧１０ｋＶ、照射電流５０ｎＡ、ビーム径約４μｍφに設定し、Ａｒイオンスパッタ速度をＳｉＯ２換算値で約３．０ｎｍ／ｍｉｎの条件により実施した。 The thickness of the coating layer 5 shall be measured as follows. That is, in the gold-coated silver bonding wire 3, the element concentration analysis is performed from the surface of the gold-coated silver bonding wire 3 in the depth direction by AES, and the position is 50% when the maximum value of the gold content existing near the surface is set to 100%. The portion to be formed is defined as a boundary portion, and the region from the boundary portion to the surface is determined as the thickness of the coating layer 5. The element distribution in the depth direction from the surface of the gold-coated silver bonding wire 3 can be measured by AES analysis. For example, concentration measurement by AES analysis is effective as a means for analyzing the concentration of each element of the coating layer 5 from the surface of the wire 1 toward the silver core material 4. Here, as an example, an Auger electron spectrometer (trade name: JAMP-9500F) manufactured by JEOL Ltd. is used, the acceleration voltage of the primary electron beam is set to 10 kV, the irradiation current is set to 50 nA, and the beam diameter is set to about 4 μmφ, and the Ar ion sputtering rate is set to SiO2. The conversion value was about 3.0 nm / min.
　実施形態のワイヤ接合構造１において、電極２とボール圧縮部６との接合界面近傍における金濃化接合領域７の形成方法は、特に限定されるものではない。金濃化接合領域７の形成方法としては、例えば金被覆銀ボンディングワイヤ３の一端にＦＡＢを形成する際に、ＦＡＢの表面に金が濃化した領域（表面金濃化領域）を形成することによって達成できる。表面に金濃化領域を形成したＦＡＢを電極２に接合してボール圧縮部６を形成することによって、電極２とボール圧縮部６との接合界面近傍に金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域７を形成することができる。詳しい形成方法については後述する。 In the wire bonding structure 1 of the embodiment, the method of forming the gold-enriched bonding region 7 in the vicinity of the bonding interface between the electrode 2 and the ball compression portion 6 is not particularly limited. As a method of forming the gold-enriched bonding region 7, for example, when forming the FAB at one end of the gold-coated silver bonding wire 3, a gold-enriched region (surface gold-enriched region) is formed on the surface of the FAB. Can be achieved by. By joining the FAB having a gold-enriched region formed on the surface to the electrode 2 to form the ball compression portion 6, the concentration of gold in the vicinity of the junction interface between the electrode 2 and the ball compression portion 6 is gold, silver, and aluminum. A gold-enriched bonding region 7 of 5 atomic% or more with respect to the total amount can be formed. The detailed forming method will be described later.
　金濃化接合領域７の形成方法の一例として、ボンディングワイヤを制御して形成する方法について説明する。すなわち、表面に金濃化領域を形成したＦＡＢを電極２に接合してボール圧縮部６を形成する方法について述べる。金被覆銀ボンディングワイヤ３を電極２に接合するにあたって、まず図４に示すように、金被覆銀ボンディングワイヤ３の一端にＦＡＢ８を形成する。ＦＡＢ８の形成条件としては、例えば金被覆銀ボンディングワイヤ３の線径が１３μｍ以上３０μｍ以下である場合に、線径に応じて放電電流値が３０ｍＡ以上１２０ｍＡ以下、ＦＡＢ８の直径がワイヤ線径の１．５倍以上２．０倍以下となるようにアーク放電条件を設定する。ボンダー装置は、例えばキューリック・アンド・ソッファ社製のボンダー装置（全自動ボンダー：ＩＣｏｎｎ　ＰＬＵＳ）などの市販品を使用することができる。当該ボンダー装置を使用する場合、装置の設定として放電時間が５０μｓ以上１０００μｓ以下、ＥＦＯ－Ｇａｐが２０ｍｉｌ以上４０ｍｉｌ以下（約６３５μｍ以上１１４３μｍ以下）、テール長さが６ｍｉｌ以上１２ｍｉｌ以下（約１５２μｍ以上３０５μｍ以下）を適用することが好ましい。また、当該ボンダー装置以外のボンダー装置を用いる場合には、当該ボンダー装置と同等の条件、例えばＦＡＢ８の直径が当該ボンダー装置と同等の大きさになる条件であればよい。 As an example of the method of forming the gold-enriched bonding region 7, a method of controlling and forming the bonding wire will be described. That is, a method of joining the FAB having the gold-enriched region formed on the surface to the electrode 2 to form the ball compression portion 6 will be described. When joining the gold-coated silver bonding wire 3 to the electrode 2, first, as shown in FIG. 4, a FAB 8 is formed at one end of the gold-coated silver bonding wire 3. As the conditions for forming the FAB8, for example, when the wire diameter of the gold-coated silver bonding wire 3 is 13 μm or more and 30 μm or less, the discharge current value is 30 mA or more and 120 mA or less according to the wire diameter, and the diameter of the FAB8 is 1 of the wire diameter. . Set the arc discharge conditions so that it is 5 times or more and 2.0 times or less. As the bonder device, for example, a commercially available product such as a bonder device (fully automatic bonder: IConn PLUS) manufactured by Curic and Sopha can be used. When using the bonder device, the device settings include a discharge time of 50 μs or more and 1000 μs or less, an EFO-Gap of 20 mil or more and 40 mil or less (about 635 μm or more and 1143 μm or less), and a tail length of 6 mil or more and 12 mil or less (about 152 μm or more and 305 μm or less). ) Is preferably applied. Further, when a bonder device other than the bonder device is used, the conditions may be the same as those of the bonder device, for example, the condition that the diameter of the FAB 8 is the same as that of the bonder device.
　このとき、銀ボンディングワイヤ表面に被覆した金被覆層５を溶融凝固してＦＡＢを作製するとき、表面の金がボール内部へ入り込んで結果的にボール表面の金濃度が下がり、相対的に銀濃度が上がり、アルミニウムを主成分とする電極に接合したときに腐食されやすいＡｇ３Ａｌ金属間化合物が生成してしまうという課題に対して、発明者らはボールを形成したときでも、固体ワイヤと同様にボール表面にも金を留めさせて相対的に銀濃度を減らしアルミニウム電極に接合したときに腐食に強いＡｇ２Ａｌ金属間化合物の生成、ならびに、非常に化学反応に対して安定している「貴」な金をワイヤ接合界面近傍に留まらせることができないか鋭意研究を重ねた。特に金被覆層に何らかの元素を添加すれば溶融したときでも金が表面に留まるのではないかと考え、金めっき時に数多くの種類の元素を添加してＦＡＢを作り表面の金濃度を分析するという実験を繰り返し行った。その結果、第１５及び１６族元素を添加するとＦＡＢ表面に金が留まることをついに発見した。 At this time, when the gold coating layer 5 coated on the surface of the silver bonding wire is melt-solidified to produce FAB, the gold on the surface enters the inside of the ball, and as a result, the gold concentration on the ball surface decreases, and the silver concentration is relatively high. In response to the problem that Ag 3 Al metal-metal compounds, which are easily corroded when bonded to an electrode containing aluminum as a main component, are formed, the inventors have formed a ball in the same manner as a solid wire. Gold is also fixed on the surface of the ball to reduce the silver concentration relatively, and when bonded to an aluminum electrode, the formation of an Ag 2 Al metal-metal compound that is resistant to corrosion, and is extremely stable against chemical reactions. We have been diligently researching whether it is possible to keep "precious" gold near the wire bonding interface. In particular, I thought that if some element was added to the gold coating layer, gold would stay on the surface even when it melted, so an experiment in which many kinds of elements were added during gold plating to make FAB and analyze the gold concentration on the surface. Was repeated. As a result, it was finally discovered that gold stayed on the surface of the FAB when the 15th and 16th group elements were added.
　通常、特別な元素を添加しない金で形成した場合、金被覆銀ボンディングワイヤ３の一端を溶融・凝固させてＦＡＢ８を形成する際に、被覆層５を構成する金が銀芯材４中に入り込んでしまう。よって、ＦＡＢ８の表面に金が濃化した領域（表面金濃化領域）を形成することができない。言い換えると、金被覆層はＦＡＢ８の形成前までは効果を発揮するものの、ＦＡＢ８の形成後には表面金濃化領域を存在させることができない。すなわち、ウェッジボンディングでは効果を発揮するが、ボールボンディングでは高信頼性の効果を十分には発揮できない。そのようなＦＡＢ８を電極２に接合しても、電極２とボール圧縮部６との接合界面近傍に金濃化接合領域７を再現性よく形成することができない。ここで、金層の厚さを単に厚くしても、銀芯材の直径と比較した場合、金層の厚さの比率は小さいため、金が銀芯材中に入り込むことを抑制できない。また、金層の厚さのみに基づいて、ＦＡＢの形成後の表面における金濃度を高めた場合、金被覆銀ワイヤというより金ワイヤに近い状態となり、材料コストが大幅に上がってしまう。また、金層の厚さをワイヤ全体における金濃度に換算して７質量％を超えるとＦＡＢのボール形成性、すなわちボールの偏芯等が生じる可能性が高くなる。 Normally, when gold is formed without adding a special element, when one end of the gold-coated silver bonding wire 3 is melted and solidified to form FAB 8, the gold constituting the coating layer 5 enters the silver core material 4. It ends up. Therefore, it is not possible to form a gold-enriched region (surface gold-enriched region) on the surface of the FAB8. In other words, although the gold-coated layer exerts its effect before the formation of FAB8, the surface gold-enriched region cannot exist after the formation of FAB8. That is, although the wedge bonding is effective, the ball bonding cannot sufficiently exhibit the high reliability effect. Even if such FAB 8 is bonded to the electrode 2, the gold-enriched bonding region 7 cannot be formed with good reproducibility in the vicinity of the bonding interface between the electrode 2 and the ball compression portion 6. Here, even if the thickness of the gold layer is simply increased, the ratio of the thickness of the gold layer is small when compared with the diameter of the silver core material, so that it is not possible to prevent gold from entering the silver core material. Further, when the gold concentration on the surface after the formation of the FAB is increased based only on the thickness of the gold layer, the state becomes closer to the gold wire rather than the gold-coated silver wire, and the material cost increases significantly. Further, if the thickness of the gold layer exceeds 7% by mass in terms of the gold concentration in the entire wire, the ball forming property of FAB, that is, the possibility of eccentricity of the ball increases.
　発明者らは前述の通り鋭意研究の結果、ＦＡＢ８の形成時における金の銀芯材４中への入り込みを抑制する解決手段を解明した。金の銀芯材４中への入り込みの抑制は、被覆層５を構成する金中に、硫黄（Ｓ）、セレン（Ｓｅ）、テルル（Ｔｅ）、ヒ素（Ａｓ）、及びアンチモン（Ｓｂ）から選ばれる少なくとも１つ以上の第１５及び１６族元素を含有させることにより得られることを見出した。さらに、量的にはワイヤ全体に対して第１５及び１６族元素の合計量は４質量ｐｐｍ以上８０質量ｐｐｍ以下が好適であることを見出した。 As mentioned above, the inventors have clarified a solution for suppressing the entry of gold into the silver core material 4 at the time of forming the FAB8. Suppression of gold entering the silver core material 4 is performed by sulfur (S), selenium (Se), tellurium (Te), arsenic (As), and antimony (Sb) in the gold constituting the coating layer 5. It has been found that it is obtained by containing at least one selected Group 15 and 16 elements. Further, it has been found that the total amount of the 15th and 16th group elements is preferably 4% by mass or more and 80% by mass or less with respect to the entire wire.
　第１５及び１６族元素による金の銀芯材４中への入り込みの抑制メカニズムは完全に解明されていないが、ＦＡＢ８が形成される過程において、被覆層５中の第１５及び１６族元素は溶融状態の被覆層５の表面張力に作用し、金が濃化した領域の形成に寄与すると推測される。従来の金被覆銀ボンディングワイヤの場合、溶融銀の表面張力は溶融金の表面張力よりも小さく、表面張力の違いにより発生する流れ（マランゴニ対流）が表面張力の小さい方から大きい方へ、つまり溶融銀（溶融ボール）から溶融金（溶融状態の被覆された金）に向かって発生するため、溶融金はボール内部へ移動する。一方、第１５及び１６族元素が被覆層５に存在する場合、溶融した被覆層５の表面張力は溶融銀よりも小さくなり、マランゴニ対流の向きが溶融金から溶融銀の方向へと反転するため、溶融金はＦＡＢ８の内部に入り込まない。従って、ＦＡＢ８の表面に表面金濃化領域９を形成することができると推測した。 Although the mechanism for suppressing the entry of gold into the silver core material 4 by the 15th and 16th elements has not been completely elucidated, the 15th and 16th elements in the coating layer 5 are melted in the process of forming the FAB8. It is presumed that it acts on the surface tension of the coating layer 5 in the state and contributes to the formation of the gold-enriched region. In the case of conventional gold-coated silver bonding wire, the surface tension of molten silver is smaller than the surface tension of molten gold, and the flow (marangoni convection) generated by the difference in surface tension is from the smaller surface tension to the larger surface tension, that is, melting. Since it is generated from silver (molten ball) toward molten gold (coated gold in a molten state), the molten gold moves inside the ball. On the other hand, when the Group 15 and Group 16 elements are present in the coating layer 5, the surface tension of the molten coating layer 5 is smaller than that of molten silver, and the direction of malangoni convection is reversed from the molten gold to the molten silver. , The molten gold does not get inside the FAB8. Therefore, it was speculated that the surface gold-enriched region 9 could be formed on the surface of FAB8.
　上述した被覆層５中の第１５及び１６族元素の効果が発揮されるタイミング及び表面金濃化領域が形成される過程について、ＦＡＢ８の形成過程に沿って説明する。ＦＡＢ８は金被覆銀ボンディングワイヤ３をリード又はバンプ上に第２接合した後、所定長さのワイヤが繰り出され、切断されたボンディングワイヤ３の先端と放電トーチの間にアーク放電を生じさせ、ワイヤ先端を溶融することにより形成される。ボンディングワイヤ３は第２接合の際キャピラリーで押し潰されることにより変形するため、ボンディングワイヤ３とキャピラリーが接触する領域は被覆層５が存在せず、芯材４が露出した状態となる。溶融ボールの形成初期段階では、この芯材４が露出したワイヤ先端のみ溶融されたボールは被覆層５が存在していない箇所が存在するため、金濃化領域は形成されてない。アーク放電により初期溶融ボールの溶融が進むにつれて、芯材４が露出していないワイヤ部分が溶融され始めると、被覆層５中の第１５及び１６族元素が溶融時の表面張力に作用し、溶融金はＦＡＢ８の内部へ入り込むことなくＦＡＢ８の表面領域に存在する。やがて、小さいボールから大きいボールへと成長してゆくが、金はボンディングワイヤ３から連続的に供給される。溶融金はアーク放電の熱により溶融した芯材４と合金化される。 The timing at which the effects of the 15th and 16th elements in the coating layer 5 described above are exhibited and the process of forming the surface gold-enriched region will be described along with the process of forming the FAB8. In the FAB8, after the gold-coated silver bonding wire 3 is second-bonded onto a lead or a bump, a wire having a predetermined length is unwound to generate an arc discharge between the tip of the cut bonding wire 3 and the discharge torch, and the wire. It is formed by melting the tip. Since the bonding wire 3 is deformed by being crushed by the capillary at the time of the second bonding, the coating layer 5 does not exist in the region where the bonding wire 3 and the capillary come into contact with each other, and the core material 4 is exposed. At the initial stage of forming the molten ball, the ball in which only the tip of the wire with the core material 4 exposed is melted has a portion where the coating layer 5 does not exist, so that the gold-concentrated region is not formed. As the initial molten ball melts due to the arc discharge, when the wire portion where the core material 4 is not exposed begins to melt, the 15th and 16th elements in the coating layer 5 act on the surface tension at the time of melting and melt. Gold is present in the surface region of the FAB8 without getting inside the FAB8. Eventually, it grows from a small ball to a large ball, but gold is continuously supplied from the bonding wire 3. The molten gold is alloyed with the core material 4 melted by the heat of the arc discharge.
　被覆層５を有する金被覆銀ボンディングワイヤ３において、金はワイヤ３の全体量に対して、２質量％以上７質量％以下の範囲で含まれることが好ましい。ワイヤ３の全体量に対する金の含有量が２質量％未満であると、銀芯材４を主体とする金被覆銀ボンディングワイヤ３に形成されたＦＡＢ８を用いて形成したボール圧縮部６と電極２との間の接合信頼性を十分に高めることができないおそれがある。ワイヤ３の全体量に対する金の含有量が７質量％を超えると、溶融時のボール形状、ひいてはＦＡＢ８の形状が偏芯等により低下し、ボール圧縮部６の形状や信頼性が損なわれると共に、金被覆銀ボンディングワイヤ３の材料コストが上昇する。ワイヤ３の直径や被覆層５の厚さにもよるが、ワイヤ３の全体量に対する金の含有量は３．５質量％以上がより好ましい。 In the gold-coated silver bonding wire 3 having the coating layer 5, gold is preferably contained in the range of 2% by mass or more and 7% by mass or less with respect to the total amount of the wire 3. When the gold content with respect to the total amount of the wire 3 is less than 2% by mass, the ball compression portion 6 and the electrode 2 formed by using the FAB 8 formed on the gold-coated silver bonding wire 3 mainly composed of the silver core material 4 There is a possibility that the joint reliability between the wire and the wire cannot be sufficiently improved. If the gold content with respect to the total amount of the wire 3 exceeds 7% by mass, the shape of the ball at the time of melting, and eventually the shape of the FAB8, deteriorates due to eccentricity or the like, and the shape and reliability of the ball compression portion 6 are impaired. The material cost of the gold-coated silver bonding wire 3 increases. Although it depends on the diameter of the wire 3 and the thickness of the coating layer 5, the gold content with respect to the total amount of the wire 3 is more preferably 3.5% by mass or more.
　被覆層５中に第１５及び１６族元素を存在させる場合、第１５及び１６族元素は上記した金被覆銀ボンディングワイヤ３の全体量に対して、４質量ｐｐｍ以上８０質量ｐｐｍ以下の範囲で含まれることが好ましい。ワイヤ３の全体量に対する第１５及び１６族元素の含有量が４質量ｐｐｍ未満であると、ＦＡＢ８の形成時における金の濃化効果、それによる表面金濃化領域の形成性を十分に得ることができない。ワイヤ３の全体量に対する第１５及び１６族元素の含有量が８０質量ｐｐｍを超えると、被覆層５にクラックや割れ等が生じやすくなり、伸線加工時に断線等の加工性、生産性が低下し、所望の線径の金被覆銀ボンディングワイヤ３が得られにくくなる。なお、第１５及び１６族元素は２種類以上を混合して適用してもよく、その場合には第１５及び１６族元素の合計量が上記した含有範囲となるように調整する。 When the Group 15 and Group 16 elements are present in the coating layer 5, the Group 15 and Group 16 elements are contained in the range of 4 mass ppm or more and 80 mass ppm or less with respect to the total amount of the gold-coated silver bonding wire 3 described above. Is preferable. When the content of the 15th and 16th elements with respect to the total amount of the wire 3 is less than 4% by mass, the gold enrichment effect at the time of forming the FAB8 and the resulting formability of the surface gold enrichment region can be sufficiently obtained. I can't. If the content of the 15th and 16th group elements with respect to the total amount of the wire 3 exceeds 80% by mass ppm, cracks and cracks are likely to occur in the coating layer 5, and the workability and productivity such as disconnection during wire drawing are lowered. However, it becomes difficult to obtain the gold-coated silver bonding wire 3 having a desired wire diameter. Two or more kinds of Group 15 and Group 16 elements may be mixed and applied, and in that case, the total amount of the Group 15 and Group 16 elements is adjusted to be within the above-mentioned content range.
　上記した第１５及び１６族元素を含む被覆層５を有する被覆銀ボンディングワイヤ１を用いた場合、被覆層５に含有させた第１５及び１６族元素により、ＦＡＢ８の表面領域、例えば形成されるＦＡＢ８の直径にもよるが表面から深さ方向に対して１０μｍ以下（あるいはＦＡＢ８の直径に対して１０％以下）の範囲に表面金濃化領域９が形成される。この表面金濃化領域９はＦＡＢ８と電極２との接合後も維持されるため、電極２とボール圧縮部６との接合界面近傍に金濃化接合領域７を形成することができる。すなわち、金濃化接合領域７を有するワイヤ接合構造１を得ることが可能になる。なお、上記した金濃化接合領域７の形成方法及び形成過程は一例であり、それに限定されるものではない。 When the coated silver bonding wire 1 having the coating layer 5 containing the above-mentioned Group 15 and 16 elements is used, the surface region of the FAB8, for example, the FAB8 formed by the Group 15 and 16 elements contained in the coating layer 5 is used. The surface gold-enriched region 9 is formed in a range of 10 μm or less (or 10% or less with respect to the diameter of FAB8) in the depth direction from the surface, although it depends on the diameter of the surface. Since the surface gold-enriched region 9 is maintained even after the FAB 8 and the electrode 2 are bonded, the gold-enriched bonding region 7 can be formed in the vicinity of the bonding interface between the electrode 2 and the ball compression portion 6. That is, it becomes possible to obtain a wire bonding structure 1 having a gold-enriched bonding region 7. The method and process of forming the gold-enriched bonding region 7 described above are merely examples, and the present invention is not limited thereto.
　例えば、ＦＡＢと電極２との接合条件について、以下のような条件でも金濃化接合領域７を形成することができる。具体的には、アルミニウム電極表面に金を蒸着する等でも金濃化接合領域７を形成するこができる。しかしながら、電極への金被覆は材料コスト、製造コストの面から非常にコスト高になってしまうため推奨しない。実施形態のワイヤ接合構造１は、電極２とボール圧縮部６との接合界面近傍に金濃化接合領域７を設けることによって、上述した電極２とボール圧縮部６との接合信頼性を高めるものであるため、金濃化接合領域７の形成方法は特に限定されるものではない。 For example, regarding the bonding conditions between the FAB and the electrode 2, the gold-concentrated bonding region 7 can be formed even under the following conditions. Specifically, the gold-concentrated bonding region 7 can be formed by depositing gold on the surface of the aluminum electrode. However, gold coating on the electrodes is not recommended because it is very costly in terms of material cost and manufacturing cost. The wire bonding structure 1 of the embodiment enhances the bonding reliability between the electrode 2 and the ball compression unit 6 described above by providing a gold-concentrated bonding region 7 in the vicinity of the bonding interface between the electrode 2 and the ball compression unit 6. Therefore, the method of forming the gold-enriched bonding region 7 is not particularly limited.
　以下に、金被覆銀ボンディングワイヤ３の全体量における金の含有量及び第１５及び１６族元素の含有量の算出方法について述べる。まず、金の含有量を算出する。ボンディングワイヤ３を希硝酸に入れ、芯材４を溶解した後、溶解液を採取する。この溶解液に塩酸を加え、超純水で定容液とする。被覆層５は希王水で溶解し、超純水で定容液とする。これらの定容液中の金の定量分析をＩＣＰ発光分光分析法（ＩＣＰ－ＡＥＳ：Ｉｎｄｕｃｔｉｖｅｌｙ　Ｃｏｕｐｌｅｄ　Ｐｌａｓｍａ　Ａｔｏｍｉｃ　Ｅｍｉｓｓｉｏｎ　Ｓｐｅｃｔｒｏｓｃｏｐｙ）で行うことにより、金含有量を測定する。 The method of calculating the gold content and the content of the 15th and 16th group elements in the total amount of the gold-coated silver bonding wire 3 will be described below. First, the gold content is calculated. The bonding wire 3 is put into dilute nitric acid to dissolve the core material 4, and then the solution is collected. Hydrochloric acid is added to this solution, and ultrapure water is used to make a constant volume solution. The coating layer 5 is dissolved in rare aqua regia and made into a constant volume solution with ultrapure water. The gold content is measured by performing quantitative analysis of gold in these constant volumes by ICP-AES (ICP-AES: Inductively Coupled Plasma Atomic Emission Spectroscopy).
　次に、第１５及び１６族元素の含有量を算出する。被覆層５のセレン及びテルルの含有量は、ボンディングワイヤ３を希硝酸に入れ、芯材４を溶融した後に被覆層５を抽出する。さらに、被覆層５を希王水で加熱分解した後、超純水で定容した溶液を用いて測定する。この定容液中のセレン、テルル、ヒ素、及びアンチモンの定量分析をＩＣＰ質量分析法（ＩＣＰ－ＭＳ：Ｉｎｄｕｃｔｉｖｅｌｙ　Ｃｏｕｐｌｅｄ　Ｐｌａｓｍａ　Ｍａｓｓ　Ｓｐｅｃｔｒｏｍｅｔｒｙ）を用いて測定する。一方、芯材４のセレン、テルル、ヒ素、及びアンチモンの含有量は、ボンディングワイヤ３を希硝酸に入れ、芯材４を溶融した液を用いてＩＣＰ－ＭＳまたはＩＣＰ－ＡＥＳにより測定する。その後、被覆層５及び芯材４の金の含有量とセレン、テルル、ヒ素、及びアンチモンの含有量からボンディングワイヤ３全体における金含有量とセレン、テルル、ヒ素、及びアンチモンの含有量を算出する。また、上記以外にもＩＣＰ－ＡＥＳに水素化物発生装置を取り付けて、セレン、テルル、ヒ素、及びアンチモンの水素化物を生成することによって分析する方法もある。また、芯材４及び被覆層５の硫黄（Ｓ）の含有量は、ボンディングワイヤ３に対して燃焼赤外線吸収法を用いて測定する。測定１回あたりのボンディングワイヤ３の重量は０．５ｇ以上とすることが好ましい。試料が溶けにくい場合、必要に応じて助燃材を使用してもよい。 Next, the contents of the 15th and 16th group elements are calculated. Regarding the content of selenium and tellurium in the coating layer 5, the bonding wire 3 is put into dilute nitric acid, the core material 4 is melted, and then the coating layer 5 is extracted. Further, after the coating layer 5 is thermally decomposed with dilute aqua regia, the measurement is carried out using a solution having a constant volume with ultrapure water. Quantitative analysis of selenium, tellurium, arsenic, and antimony in this constant volume solution is measured using ICP mass spectrometry (ICP-MS: Inductively Coupled Plasma Mass Spectrometry). On the other hand, the content of selenium, tellurium, arsenic, and antimony in the core material 4 is measured by ICP-MS or ICP-AES using a liquid obtained by putting the bonding wire 3 in dilute nitric acid and melting the core material 4. Then, the gold content and the content of selenium, tellurium, arsenic, and antimony in the entire bonding wire 3 are calculated from the gold content of the coating layer 5 and the core material 4 and the contents of selenium, tellurium, arsenic, and antimony. .. In addition to the above, there is also a method in which a hydride generator is attached to ICP-AES to generate hydrides of selenium, tellurium, arsenic, and antimony for analysis. The sulfur (S) content of the core material 4 and the coating layer 5 is measured with respect to the bonding wire 3 by using a combustion infrared absorption method. The weight of the bonding wire 3 per measurement is preferably 0.5 g or more. If the sample is difficult to dissolve, a combustion improver may be used if necessary.
　次に、ボンディングワイヤの製造方法について説明する。芯材４として銀を用いる場合には、所定の純度の銀を溶解させ、また銀合金を用いる場合には、所定の純度の銀を添加元素と共に溶解させることによって、銀芯材材料又は銀合金芯材材料が得られる。溶解には、アーク加熱炉、高周波加熱炉、抵抗加熱炉、連続鋳造炉等の加熱炉が用いられる。大気中からの酸素や水素の混入を防止する目的で、加熱炉の銀溶湯の上部は真空あるいはアルゴン、窒素等の不活性ガス雰囲気に保持することが好ましい。溶解させた芯材材料は、加熱炉から所定の線径となるように鋳造凝固させるか、溶融した芯材材料を鋳型に鋳造してインゴットを作り、そのインゴットをロール圧延した後、所定の線径まで伸線して銀線材（純銀線材及び銀合金線材を含む）が得られる。 Next, the manufacturing method of the bonding wire will be described. When silver is used as the core material 4, silver of a predetermined purity is dissolved, and when a silver alloy is used, silver of a predetermined purity is dissolved together with an additive element to form a silver core material or a silver alloy. A core material is obtained. For melting, a heating furnace such as an arc heating furnace, a high frequency heating furnace, a resistance heating furnace, or a continuous casting furnace is used. For the purpose of preventing the mixing of oxygen and hydrogen from the atmosphere, it is preferable to keep the upper part of the silver molten metal in the heating furnace in a vacuum or an atmosphere of an inert gas such as argon or nitrogen. The melted core material is cast and solidified from a heating furnace so that it has a predetermined wire diameter, or the melted core material is cast into a mold to make an ingot, and the ingot is rolled and then a predetermined wire. A silver wire (including a sterling silver wire and a silver alloy wire) is obtained by drawing the wire to a diameter.
　銀線材の表面に金層を形成する方法としては、例えばめっき法（湿式法）や蒸着法（乾式法）が用いられる。めっき法は電解めっき法と無電解めっき法のいずれの方法であってもよい。ストライクめっきやフラッシュめっき等の電解めっきでは、めっき速度が速く、また金めっきに適用すると、金層の銀線材への密着性が良好であるために好ましい。めっき法で金層内に硫黄族元素を含有させるためには、例えば上記電解めっきにおいて、金めっき液に硫黄、セレン、テルル、ヒ素、及びアンチモンから選ばれる少なくとも１つを含むめっき添加剤を含有させためっき液を使用する。この際、めっき添加剤の種類や量を調整することによって、被覆層５中の第１５及び１６族元素含有量を調整することができ、さらにワイヤ３中の第１５及び１６族元素含有量を調整することができる。 As a method of forming a gold layer on the surface of a silver wire, for example, a plating method (wet method) or a vapor deposition method (dry method) is used. The plating method may be either an electrolytic plating method or an electroless plating method. Electroplating such as strike plating and flash plating is preferable because the plating speed is high, and when applied to gold plating, the adhesion of the gold layer to the silver wire is good. In order to contain a sulfur group element in the gold layer by the plating method, for example, in the above electroplating, the gold plating solution contains a plating additive containing at least one selected from sulfur, selenium, tellurium, arsenic, and antimony. Use the plated solution. At this time, the content of Group 15 and Group 16 elements in the coating layer 5 can be adjusted by adjusting the type and amount of the plating additive, and the content of Group 15 and Group 16 elements in the wire 3 can be adjusted. Can be adjusted.
　蒸着法としては、スパッタ法、イオンプレーティング法、真空蒸着法等の物理蒸着（ＰＶＤ）や、熱ＣＶＤ、プラズマＣＶＤ、有機金属気相成長法（ＭＯＣＶＤ）等の化学蒸着（ＣＶＤ）を利用することができる。これらの方法によれば、形成後の金被覆層の洗浄が不要であり、洗浄時の表面汚染等の懸念がない。蒸着法によって金層内に第１５及び１６族元素を含有させる手法としては、第１５及び１６族元素を含有させた金ターゲットを用いて、マグネトロンスパッタリング等によって金層を形成する手法がある。それ以外の方法を適用する場合も、金材料に第１５及び１６族元素を含有させた原料を用いればよい。 As the vapor deposition method, physical vapor deposition (PVD) such as a sputtering method, an ion plating method, or a vacuum vapor deposition method, or chemical vapor deposition (CVD) such as thermal CVD, plasma CVD, or metalorganic vapor deposition (MOCVD) is used. be able to. According to these methods, it is not necessary to clean the gold coating layer after formation, and there is no concern about surface contamination during cleaning. As a method of containing the 15th and 16th group elements in the gold layer by the vapor deposition method, there is a method of forming the gold layer by magnetron sputtering or the like using a gold target containing the 15th and 16th group elements. When other methods are also applied, a raw material containing Group 15 and Group 16 elements in the gold material may be used.
　金層を形成するタイミングは特に限定されない。金層を被覆した銀線材を最終線径まで伸線し、必要に応じて熱処理することによって、銀芯材４の表面に被覆層５を設けた金被覆銀ボンディングワイヤ３が製造される。伸線加工は銀線材の段階で実施してもよいし、またある程度の線径まで銀線材に伸線加工を施し、金層を形成した後に最終線径まで伸線加工してもよい。伸線加工と熱処理は、段階的に行われてもよい。伸線加工の加工率は、製造される金被覆銀ボンディングワイヤ３の最終線径や用途等に応じて決定される。伸線加工の加工率は、一般的には銀線材を最終線径に加工するまでの加工率として９０％以上であることが好ましい。この加工率は、ワイヤ断面積の減少率として算出することができる。伸線加工は、複数のダイヤモンドダイスを用いて、段階的に線径を縮小するように行うことが好ましい。この場合、ダイヤモンドダイス１つあたりの減面率（加工率）は５％以上１５％以下が好ましい。 The timing of forming the gold layer is not particularly limited. A gold-coated silver bonding wire 3 having a coating layer 5 on the surface of the silver core material 4 is manufactured by drawing a silver wire material coated with a gold layer to the final wire diameter and heat-treating it if necessary. The wire drawing process may be performed at the stage of the silver wire rod, or the silver wire rod may be wire drawn to a certain diameter to form a gold layer and then drawn to the final wire diameter. The wire drawing process and the heat treatment may be performed step by step. The processing rate of the wire drawing process is determined according to the final wire diameter of the gold-coated silver bonding wire 3 to be manufactured, the application, and the like. Generally, the processing rate of wire drawing is preferably 90% or more as the processing rate until the silver wire is processed to the final wire diameter. This processing rate can be calculated as a reduction rate of the wire cross-sectional area. It is preferable that the wire drawing process is performed by using a plurality of diamond dies so as to gradually reduce the wire diameter. In this case, the surface reduction rate (processing rate) per diamond die is preferably 5% or more and 15% or less.
　金層を被覆した銀線材を最終線径まで伸線した後に、最終熱処理を実施することが好ましい。最終熱処理は、最終線径において、ワイヤ３の内部に残留する金属組織の歪みを除去する歪み取り熱処理や必要とされるワイヤ特性を考慮して実行される。歪み取り熱処理は、必要とされるワイヤ特性を考慮して、温度及び時間を決定することが好ましい。その他、ワイヤ製造の任意の段階で、目的に応じた熱処理を施してもよい。このような熱処理としては、ワイヤの伸線過程での歪み取り熱処理、金層を形成した後に接合強度を上げるための拡散熱処理等がある。拡散熱処理を行うことで、芯材４と被覆層５との接合強度を向上させることができる。熱処理は、所定の温度に加熱された加熱雰囲気内にワイヤを通過させて熱処理を行う走間熱処理が、熱処理条件を調節しやすいために好ましい。走間熱処理の場合、熱処理時間はワイヤの通過速度と加熱容器内のワイヤの通過距離によって算出することができる。加熱容器としては電気炉等が使用される。 It is preferable to carry out the final heat treatment after drawing the silver wire material coated with the gold layer to the final wire diameter. The final heat treatment is performed in consideration of the strain removing heat treatment for removing the strain of the metal structure remaining inside the wire 3 and the required wire characteristics in the final wire diameter. For the strain removing heat treatment, it is preferable to determine the temperature and time in consideration of the required wire characteristics. In addition, heat treatment may be performed according to the purpose at any stage of wire production. Examples of such a heat treatment include a strain removing heat treatment in the wire drawing process, a diffusion heat treatment for increasing the bonding strength after forming a gold layer, and the like. By performing the diffusion heat treatment, the bonding strength between the core material 4 and the coating layer 5 can be improved. As the heat treatment, a run-run heat treatment in which a wire is passed through a heating atmosphere heated to a predetermined temperature to perform the heat treatment is preferable because the heat treatment conditions can be easily adjusted. In the case of inter-running heat treatment, the heat treatment time can be calculated from the passing speed of the wire and the passing distance of the wire in the heating container. An electric furnace or the like is used as the heating container.
　次に、上述した金被覆銀ボンディングワイヤ３の一端にＦＡＢ８を形成する。ＦＡＢ８は、ワイヤ３の先端と放電トーチの間にアーク放電を生じさせ、ワイヤ３の先端を溶融することにより形成される。金被覆銀ボンディングワイヤ３の一端に形成されたＦＡＢ８を、超音波併用熱圧着ボンディング法等により電極２に接合する。電極２に接触したＦＡＢ８を、超音波併用熱圧着時の圧力により変形させつつ、超音波及び熱により電極２に接合することによって、電極２に接合されたボール圧縮部６を形成することができる。 Next, the FAB 8 is formed at one end of the gold-coated silver bonding wire 3 described above. The FAB 8 is formed by generating an arc discharge between the tip of the wire 3 and the discharge torch and melting the tip of the wire 3. The FAB8 formed at one end of the gold-coated silver bonding wire 3 is bonded to the electrode 2 by a thermocompression bonding method using ultrasonic waves or the like. The ball compression portion 6 joined to the electrode 2 can be formed by joining the FAB 8 in contact with the electrode 2 to the electrode 2 by ultrasonic waves and heat while deforming the FAB 8 in contact with the electrode 2 by the pressure at the time of thermocompression bonding using ultrasonic waves. ..
（半導体装置）
　次に、実施形態のワイヤ接合構造を適用した半導体装置について、図５ないし図７を参照して説明する。なお、図５は実施形態の半導体装置の樹脂封止する前の段階を示す断面図、図６は実施形態の半導体装置の樹脂封止した段階を示す断面図、図７は実施形態の半導体装置における半導体チップの電極とボンディングワイヤとの接合部を拡大して示す断面図である。 (Semiconductor device)
Next, the semiconductor device to which the wire bonding structure of the embodiment is applied will be described with reference to FIGS. 5 to 7. 5 is a cross-sectional view showing a stage before resin sealing of the semiconductor device of the embodiment, FIG. 6 is a cross-sectional view showing a stage of resin sealing of the semiconductor device of the embodiment, and FIG. 7 is a semiconductor device of the embodiment. It is a cross-sectional view which shows the junction | bonding part of the semiconductor chip electrode and a bonding wire in 1) in an enlarged manner.
　実施形態の半導体装置１０（樹脂封止する前の半導体装置１０Ｘ）は、図５及び図６に示すように、外部電極１１を有する回路基板１２と、回路基板１２上に配置され、少なくとも１つの電極（チップ電極）１３をそれぞれ有する複数の半導体チップ１４（１４Ａ、１４Ｂ、１４Ｃ）と、回路基板１２の外部電極１１と半導体チップ１４の電極１３、及び複数の半導体チップ１４の電極１３間を接続するボンディングワイヤ１５とを備えている。回路基板１２には、例えば樹脂材やセラミックス材等の絶縁基材の表面や内部に配線網を設けたプリント配線板やセラミックス回路基板等が用いられる。 As shown in FIGS. 5 and 6, the semiconductor device 10 of the embodiment (semiconductor device 10X before resin sealing) is arranged on the circuit board 12 having the external electrode 11 and at least one. A plurality of semiconductor chips 14 (14A, 14B, 14C) each having an electrode (chip electrode) 13 are connected to an external electrode 11 of the circuit board 12, an electrode 13 of the semiconductor chip 14, and an electrode 13 of the plurality of semiconductor chips 14. The bonding wire 15 is provided. As the circuit board 12, for example, a printed wiring board or a ceramic circuit board having a wiring network provided on the surface or inside of an insulating base material such as a resin material or a ceramic material is used.
　なお、図５及び図６は回路基板１２上に複数の半導体チップ１４を実装した半導体装置１０を示しているが、半導体装置１０の構成はこれに限られるものではない。例えば、半導体チップはリードフレーム上に実装されていてもよく、その場合には半導体チップの電極はリードフレームの外部電極として機能するアウターリードにボンディングワイヤ１５を介して接続される。半導体チップの回路基板やリードフレームに対する搭載数は、１つ及び複数のいずれであってもよい。ボンディングワイヤ１５は、回路基板１２の外部電極１１と半導体チップ１４の電極１３、リードフレームと半導体チップの電極、及び複数の半導体チップ１４の電極１３間の少なくとも１つに適用される。 Note that FIGS. 5 and 6 show a semiconductor device 10 in which a plurality of semiconductor chips 14 are mounted on a circuit board 12, but the configuration of the semiconductor device 10 is not limited to this. For example, the semiconductor chip may be mounted on a lead frame, in which case the electrodes of the semiconductor chip are connected to an outer lead that functions as an external electrode of the lead frame via a bonding wire 15. The number of semiconductor chips mounted on the circuit board or lead frame may be one or a plurality. The bonding wire 15 is applied to at least one of the external electrode 11 of the circuit board 12 and the electrode 13 of the semiconductor chip 14, the lead frame and the electrode of the semiconductor chip, and the electrodes 13 of the plurality of semiconductor chips 14.
　図５及び図６に示す半導体装置１０の複数の半導体チップ１４のうち、半導体チップ１４Ａ、１４Ｃは回路基板１２のチップ実装領域にダイボンディング材１６を介して実装されている。半導体チップ１４Ｂは半導体チップ１４Ａ上にダイボンディング材１６を介して実装されている。半導体チップ１４Ａの１つの電極１３はボンディングワイヤ１５を介して回路基板１２の外部電極１１と接続されており、他の１つの電極１３はボンディングワイヤ１５を介して半導体チップ１４Ｂの電極１３と接続されており、さらに他の１つの電極１３はボンディングワイヤ１５を介して半導体チップ１４Ｃの電極１３と接続されている。半導体チップ１４Ｂの他の１つの電極１３は、ボンディングワイヤ１５を介して回路基板１２の外部電極１１と接続されている。半導体チップ１４Ｃの他の１つの電極１３は、ボンディングワイヤ１５を介して回路基板１２の外部電極１１と接続されている。 Of the plurality of semiconductor chips 14 of the semiconductor device 10 shown in FIGS. 5 and 6, the semiconductor chips 14A and 14C are mounted in the chip mounting region of the circuit board 12 via the die bonding material 16. The semiconductor chip 14B is mounted on the semiconductor chip 14A via a die bonding material 16. One electrode 13 of the semiconductor chip 14A is connected to the external electrode 11 of the circuit board 12 via the bonding wire 15, and the other electrode 13 is connected to the electrode 13 of the semiconductor chip 14B via the bonding wire 15. The other electrode 13 is connected to the electrode 13 of the semiconductor chip 14C via a bonding wire 15. The other electrode 13 of the semiconductor chip 14B is connected to the external electrode 11 of the circuit board 12 via the bonding wire 15. The other electrode 13 of the semiconductor chip 14C is connected to the external electrode 11 of the circuit board 12 via the bonding wire 15.
　半導体チップ１４は、シリコン（Ｓｉ）半導体や化合物半導体等からなる集積回路（ＩＣ）を備えている。チップ電極１３は、例えば、少なくとも最表面にアルミニウム（Ａｌ）層、ＡｌＳｉＣｕ、ＡｌＣｕ等のアルミニウム合金層を有するアルミニウム電極からなる。アルミニウム電極は、例えばシリコン（Ｓｉ）基板の表面に、内部配線と電気的に接続するようにＡｌやＡｌ合金等の電極材料を被覆することにより形成される。半導体チップ１４は、外部電極１１及びボンディングワイヤ１５を介して、外部デバイスとの間でデータ通信をしたり、また外部デバイスから電力を供給したりする。 The semiconductor chip 14 includes an integrated circuit (IC) made of a silicon (Si) semiconductor, a compound semiconductor, or the like. The chip electrode 13 is made of, for example, an aluminum electrode having an aluminum (Al) layer and an aluminum alloy layer such as AlSiCu or AlCu on the outermost surface. The aluminum electrode is formed by, for example, coating the surface of a silicon (Si) substrate with an electrode material such as Al or an Al alloy so as to electrically connect to the internal wiring. The semiconductor chip 14 communicates data with an external device via the external electrode 11 and the bonding wire 15, and supplies electric power from the external device.
　回路基板１２の外部電極１１は、回路基板１２に実装された半導体チップ１４の電極１３とボンディングワイヤ１５を介して電気的に接続されている。実施形態の半導体装置１０において、ボンディングワイヤ１５の一端は、チップ電極１３にボール接合（第１接合）されており、他端は外部電極１１にウェッジ接合（第２接合）されている。複数の半導体チップ１４の電極１３間をボンディングワイヤ１５で接続する場合も同様であり、ボンディングワイヤ１５の一端は、半導体チップ１４のチップ電極１３にボール接合（第１接合）され、他端は他の半導体チップ１４のチップ電極１３にウェッジ接合（第２接合）される。なお、半導体チップ１４の電極１３とは、半導体チップ１４上にある電極パッドにあらかじめバンプを接合した形態も含むものとする（図示しない）。 The external electrode 11 of the circuit board 12 is electrically connected to the electrode 13 of the semiconductor chip 14 mounted on the circuit board 12 via the bonding wire 15. In the semiconductor device 10 of the embodiment, one end of the bonding wire 15 is ball-bonded (first bonded) to the chip electrode 13, and the other end is wedge-bonded (second bonded) to the external electrode 11. The same applies to the case where the electrodes 13 of the plurality of semiconductor chips 14 are connected by the bonding wire 15. One end of the bonding wire 15 is ball-bonded (first bonded) to the chip electrode 13 of the semiconductor chip 14, and the other end is the other. Wedge bonding (second bonding) is performed on the chip electrode 13 of the semiconductor chip 14 of the above. The electrode 13 of the semiconductor chip 14 includes a form in which a bump is previously bonded to an electrode pad on the semiconductor chip 14 (not shown).
　ボンディングワイヤ１５の一端をチップ電極１３にボール接合するにあたって、ボンディングワイヤ１５の一端を放電等により溶融し、表面張力等により球状に凝固させることによって、図４に示したようなＦＡＢ８を形成する。このようなＦＡＢ８を、超音波併用熱圧着ボンディング法等によりチップ電極１３にボンディングすることによって、図１に示したワイヤ接合構造１が形成される。すなわち、図７に示すように、ボンディングワイヤ１５とチップ電極１３とチップ電極１３に接合されたボール圧縮部６とを有するワイヤ接合構造１が形成される。この後、複数の半導体チップ１４及びボンディングワイヤ１５を樹脂封止するように、回路基材１２上に封止樹脂層１７を形成することによって、半導体装置１０が製造される。半導体装置１０の具体例としては、ロジックＩＣ、アナログＩＣ、ディスクリート半導体、半導体メモリ、光半導体等が挙げられる。 When one end of the bonding wire 15 is ball-bonded to the chip electrode 13, one end of the bonding wire 15 is melted by discharge or the like and solidified into a spherical shape by surface tension or the like to form FAB8 as shown in FIG. By bonding such FAB 8 to the chip electrode 13 by a thermocompression bonding method using ultrasonic waves or the like, the wire bonding structure 1 shown in FIG. 1 is formed. That is, as shown in FIG. 7, a wire bonding structure 1 having a bonding wire 15, a chip electrode 13, and a ball compression portion 6 bonded to the chip electrode 13 is formed. After that, the semiconductor device 10 is manufactured by forming the sealing resin layer 17 on the circuit base material 12 so that the plurality of semiconductor chips 14 and the bonding wires 15 are resin-sealed. Specific examples of the semiconductor device 10 include logic ICs, analog ICs, discrete semiconductors, semiconductor memories, optical semiconductors, and the like.
　半導体装置１０におけるワイヤ接合構造１には、前述した実施形態のワイヤ接合構造１が適用される。すなわち、ボンディングワイヤ１５の一端に設けられたボール圧縮部６とチップ電極１３との接合界面近傍には、図１に示したように、金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域７が設けられている。このような金濃化接合領域７を存在させ、接合界面近傍における金濃度を高めることによって、非常に脆く、腐食されやすいＡｇ３Ａｌ金属間化合物の形成を抑制し、耐食性に優れて安定なＡｇ２Ａｌ金属間化合物を形成することによって、電極２とボール圧縮部６との接合信頼性を向上させることができ、ひいては半導体装置１の信頼性を高めることが可能になる。 The wire bonding structure 1 of the above-described embodiment is applied to the wire bonding structure 1 in the semiconductor device 10. That is, as shown in FIG. 1, the concentration of gold is relative to the total amount of gold, silver, and aluminum in the vicinity of the bonding interface between the ball compression portion 6 provided at one end of the bonding wire 15 and the chip electrode 13. A gold-enriched bonding region 7 of 5 atomic% or more is provided. By presenting such a gold-enriched bonding region 7 and increasing the gold concentration in the vicinity of the bonding interface , the formation of a very brittle and easily corroded Ag 3 Al intermetallic compound is suppressed, and Ag has excellent corrosion resistance and is stable. by forming a 2 Al intermetallic compound, it is possible to improve the bonding reliability between the electrode 2 and the ball compression unit 6, it is possible to enhance the reliability of the semiconductor device 1 therefore.
　次に、本発明の実施例について説明する。本発明は以下の実施例に限定されない。例１～２６は実施例であり、例２７～３２は比較例である。 Next, examples of the present invention will be described. The present invention is not limited to the following examples. Examples 1 to 26 are examples, and examples 27 to 32 are comparative examples.
（実施例１～２６）
　芯材として、連続鋳造で作製した銀もしくは銀合金の芯材を用意し、連続伸線を行って中間線径０．０５ｍｍ～１．０ｍｍまで加工した。さらに、中間線径の銀線材に、硫黄、セレン、テルル、ヒ素、及びアンチモンの各々の添加剤を適量添加した金電解めっき浴を使用し、銀線材を連続的に送線しながら浸漬した状態で、銀線材に電流密度０．２０Ａ／ｄｍ２以上２．０Ａ／ｄｍ２以下で電流を流し、金被覆層を形成した。この後、最終線径のφ２０μｍまで伸線加工したワイヤに最終熱処理を施し、実施例１から実施例２６の金被覆銀ボンディングワイヤを作製した。 (Examples 1 to 26)
As a core material, a silver or silver alloy core material produced by continuous casting was prepared, and continuous wire drawing was performed to process an intermediate wire diameter of 0.05 mm to 1.0 mm. Furthermore, a gold electroplating bath in which appropriate amounts of each of sulfur, selenium, tellurium, arsenic, and antimony additives are added to a silver wire having an intermediate wire diameter is used, and the silver wire is immersed while continuously transmitting the wire. Then, a current was passed through the silver wire at a current density of 0.20 A / dm 2 or more and 2.0 A / dm 2 or less to form a gold coating layer. After that, the wire drawn to a final wire diameter of φ20 μm was subjected to final heat treatment to prepare gold-coated silver bonding wires of Examples 1 to 26.
（比較例２７～３２）
　実施例と同様にして、金被覆銀ボンディングワイヤを作製した。ボンディングワイヤの組成については表１にまとめて示す。 (Comparative Examples 27 to 32)
A gold-coated silver bonding wire was produced in the same manner as in the examples. The composition of the bonding wire is summarized in Table 1.
（含有量測定）
　金被覆銀ボンディングワイヤ中の金含有量（金は被覆層由来であり銀芯材には含まれていない）、銀芯材への添加元素であるパラジウム、インジウム、及び第１５及び１６族元素含有量は、前述した方法前述した方法（ (Content measurement)
Gold content in gold-coated silver bonding wire (gold is derived from the coating layer and is not contained in the silver core material), and contains palladium, indium, and Group 15 and 16 elements that are additives to the silver core material. The amount is the method described above and the method described above (
、 ,
参照）にしたがって測定した。その結果を表１に示す。 Reference). The results are shown in Table 1.
（ワイヤ表面割れ観察）
　中間線径及び最終線径の金被覆銀ボンディングワイヤの外観をキーエンス社製のレーザー顕微鏡（商品名：ＶＫ－Ｘ２００）を用いて、高倍率による金被膜の割れ（亀裂）の有無を確認した。サンプリング本数は合計１０本で、主に伸線加工時に発生する引張応力により、金被膜に亀裂が発生して銀芯材の露出が１本でも見られた場合を不合格（X）、１本も見られなかった場合を合格（○）とした。その結果を表１に示す。なお、表面割れのあったサンプルについては、これ以降のボール形成性やＨＡＳＴ評価等を実施しなかったので表中には未実施（－）と示した。 (Observation of wire surface cracks)
The appearance of the gold-coated silver bonding wires having an intermediate wire diameter and a final wire diameter was confirmed by using a laser microscope (trade name: VK-X200) manufactured by KEYENCE Corporation to confirm the presence or absence of cracks in the gold coating due to high magnification. The total number of samples is 10, and if the gold film is cracked due to the tensile stress generated mainly during wire drawing and even one silver core material is exposed, it is rejected (X), one. The case where was not seen was regarded as a pass (○). The results are shown in Table 1. For samples with surface cracks, ball formation and HAST evaluation were not performed after that, so they are shown as unimplemented (-) in the table.
（ＦＡＢ作製条件）
　上述の条件によりＦＡＢを作製し、上述の接合条件で電極に接合した（［００２４］、［００４０］参照）。 (FAB production conditions)
FAB was prepared under the above-mentioned conditions and bonded to the electrodes under the above-mentioned bonding conditions (see [0024] and [0040]).
（ボール形成性）
　ボール形成性はボール圧着後の真円性にて評価することができる。３０本の第１接合について、接合されたボールを上部から観察し、圧着ボールの最大幅とこれに直交する幅を測定し、最大幅とこれに直交する幅の比（最大幅／直交する幅）を求めた。この比の値の、上記３０本の平均値が１．００以上１．１５未満であれば良好（○）、１．１５以上であれば問題ありで不良（Ｘ）とした (Ball formability)
The ball formability can be evaluated by the roundness after the ball is crimped. For the 30 first joints, observe the joined balls from above, measure the maximum width of the crimping balls and the width orthogonal to this, and the ratio of the maximum width to the width orthogonal to this (maximum width / orthogonal width). ) Was asked. If the average value of the above 30 pieces of this ratio is 1.00 or more and less than 1.15, it is good (◯), and if it is 1.15 or more, there is a problem and it is bad (X).
（金濃化接合領域等の測定）
　次に、上述した方法で作製したサンプルの接合界面近傍について金濃化接合領域の有無（金濃度分析値）、及び、ボール圧縮部の全長に対して８分の１の箇所とボール圧縮部の端との間に金濃化接合領域が存在するか、また、接合界面近傍における占有率が２５％以上あるかを測定した。１サンプルにつき電極とボール接合との接合構造が４組できる。その４組について上記３つの評価を行なった。金濃化接合領域の金濃度についてはパラジウムやインジウム、及び第１５及び１６族元素等の添加元素を考慮せずに求めた。すなわち、分母に入れずに求めた。表１の金濃化接合領域の金の分析値は４組の接合構造のうち１番金濃度が高かった組の値を採用し、その組の接合界面近傍におけるライン分析の測定点で金濃度が高い順から３点選び、その３点の平均値を記載した。圧縮部の両端から上記８分の１の箇所までの間に金濃化接合領域があるかないかの評価は、４組のボールすべてであった場合は合格（○）で、１組でも無ければ不合格（Ｘ）とした。同様に金濃化接合領域の占有率に関しても４組の接合構造すべて２５％以上あった場合には合格（○）、１組でも２５％未満だった場合は不合格（Ｘ）と記載した。（各評価方法の詳細については［００２７］から［００３２］を参照）。 (Measurement of gold-enriched joint region, etc.)
Next, the presence or absence of a gold-enriched bonding region (gold concentration analysis value) in the vicinity of the bonding interface of the sample prepared by the above method, and one-eighth of the total length of the ball compression section and the ball compression section It was measured whether there was a gold-enriched bonding region between the edges and the occupancy rate in the vicinity of the bonding interface was 25% or more. Four sets of bonding structures of electrodes and ball bonding can be formed for each sample. The above three evaluations were performed on the four sets. The gold concentration in the gold-enriched bonding region was determined without considering additive elements such as palladium, indium, and Group 15 and 16 elements. That is, it was calculated without being included in the denominator. For the gold analysis value of the gold-enriched joint region in Table 1, the value of the set with the highest gold concentration among the four sets of joint structures was adopted, and the gold concentration at the measurement point of the line analysis near the joint interface of that set was adopted. 3 points were selected from the highest order, and the average value of the 3 points was described. The evaluation of whether or not there is a gold-enriched joint region between both ends of the compression part and the above-mentioned one-eighth part is passed (○) if all four sets of balls are used, and if there is no one set. It was rejected (X). Similarly, regarding the occupancy rate of the gold-enriched joint region, it was described as passing (◯) when all four sets of joining structures were 25% or more, and failing (X) when even one set was less than 25%. (Refer to [0027] to [0032] for details of each evaluation method).
（ＨＡＳＴ試験用サンプルの作製）
　各例で得られた金被覆銀ボンディングワイヤについて、市販のボンダー装置（Ｋ＆Ｓ　ＩＣＯＮＮ）にて、ＢＧＡ（Ｂａｌｌ　Ｇｒｉｄ　Ａｒｒａｙ）基板上の厚さ３００μｍのＳｉチップ上の厚さ０．８μｍのＡｌ－０．５質量％Ｃｕ合金電極上に、それぞれ上記フリーエアーボール、ボール接合及び第二接合と同様の条件でワイヤボンディングを行なった。つまり、フリーエアーボールの形成は、全自動ボンダーを用いて、ボール径が線径の１．５～２．３倍の範囲の所定の大きさになるように、エレクトロン・フレーム・オフ（ＥＦＯ）電流を３０～９０ｍＡの範囲、放電時間を５０～１０００μｓの範囲でそれぞれ所定の値に調節し、ＥＦＯ－Ｇａｐが２５～４５ｍｉｌ（約６３５～１１４３μｍ）、テール長さが６～１２ｍｉｌ（約１５２～３０５μｍ）で行なった。 (Preparation of sample for HAST test)
For the gold-coated silver bonding wires obtained in each example, a commercially available bonder device (K & S ICONN) was used to obtain an Al-0 having a thickness of 0.8 μm on a Si chip having a thickness of 300 μm on a BGA (Ball Grid Alloy) substrate. Wire bonding was performed on the 5.5 mass% Cu alloy electrodes under the same conditions as the above-mentioned free air balls, ball bonding and second bonding, respectively. That is, the formation of the free air ball is performed by electron frame off (EFO) using a fully automatic bonder so that the ball diameter has a predetermined size in the range of 1.5 to 2.3 times the wire diameter. Adjust the current to a predetermined value in the range of 30 to 90 mA and the discharge time in the range of 50 to 1000 μs, EFO-Gap is 25 to 45 mil (about 635 to 1143 μm), and the tail length is 6 to 12 mil (about 152 to 152 to). 305 μm).
　第１接合の条件は、例えば、ワイヤ線径φが２０μｍの実施例１については、ボール径が３６μｍのフリーエアーボールを形成し、ボール圧縮部の高さが１０μｍ、ボール圧縮部の接合面に平行方向の最大幅が４５μｍ、ボールシェア強度１５ｇｆ以上となるようにボンディング条件を調整した。この際、チップ上のＡｌ－０．５質量％Ｃｕ合金電極は隣り合うボンド部のみが電気的に接続されて、隣り合う２本のワイヤ同士で電気的に１つの回路を形成しており、計３２０回路が形成する。その後、このＢＧＡ基板上のＳｉチップを市販のトランズファーモールド機（第一精工製株式会社、ＧＰＧＰ－ＰＲＯ－ＬＡＢ８０）を使って樹脂封止して試験片を得た。なお、封止した樹脂は市販されているハロゲンフリーの樹脂（塩素濃度１５ｐｐｍ以下、ｐｈ６以上７以下）を使用した。また、実施例の試験片についてはボール圧縮部の高さが７～１３μｍ、ボール圧縮部の接合面に平行方向の最大幅は形成されたフリーエアーボールの１．２倍となるようにボール接合した。 The conditions for the first joining are, for example, in Example 1 in which the wire wire diameter φ is 20 μm, a free air ball having a ball diameter of 36 μm is formed, the height of the ball compression portion is 10 μm, and the joint surface of the ball compression portion is formed. The bonding conditions were adjusted so that the maximum width in the parallel direction was 45 μm and the ball share strength was 15 gf or more. At this time, in the Al-0.5 mass% Cu alloy electrode on the chip, only the adjacent bond portions are electrically connected, and two adjacent wires electrically form one circuit. A total of 320 circuits are formed. Then, the Si chip on the BGA substrate was resin-sealed using a commercially available transfur mold machine (Daiichi Seiko Co., Ltd., GPGP-PRO-LAB80) to obtain a test piece. As the sealed resin, a commercially available halogen-free resin (chlorine concentration of 15 ppm or less, ph6 or more and 7 or less) was used. For the test piece of the example, the height of the ball compression portion is 7 to 13 μm, and the maximum width in the direction parallel to the joint surface of the ball compression portion is 1.2 times that of the formed free air ball. did.
＜ＨＡＳＴ（Ｈｉｇｈｌｙ　Ａｃｃｅｌｅｒａｔｅｄ　Ｔｅｍｐｅｒａｔｕｒｅ　ａｎｄＨｕｍｉｄｉｔｙ　Ｓｔｒｅｓｓ　Ｔｅｓｔ（高温高湿環境暴露試験））＞
　この試験片についてＨＡＳＴ装置（株式会社平山製作所、ＰＣＲ８Ｄ）を用いて、１３０℃、８５．０％ＲＨ（相対湿度）、２．２気圧で２００時間保持した。保持前後に上記３２０回路の電気抵抗値を測定し、保持後の電気抵抗値が保持前の電気抵抗値に比べすべての回路で上昇率が８％以下であった場合を（Ｓ）、１回路でも８％を超えそれ以外の回路が１０％以下である場合を（Ａ）、１回路でも１０％を超えそれ以外の回路が１５％以下である場合を（Ｂ）、１回路でも１５％を超えそれ以外の回路が２０％以下である場合を（Ｃ）、２０％超えた回路が一つでもあった場合を不良（×）とした。２０％以下はＳからＣのランクを付けたが製品上問題ないレベルなので合格とした。 <HAST (Highly Accelerated Temperature and Humidity Stress Test)>
This test piece was held at 130 ° C., 85.0% RH (relative humidity), and 2.2 atm for 200 hours using a HAST apparatus (Hirayama Seisakusho Co., Ltd., PCR8D). The electric resistance value of the 320 circuits is measured before and after holding, and when the electric resistance value after holding is 8% or less in all circuits as compared with the electric resistance value before holding (S), one circuit. But when it exceeds 8% and the other circuits are 10% or less (A), when even one circuit exceeds 10% and the other circuits are 15% or less (B), even one circuit is 15%. The case where the other circuits exceeded 20% was regarded as (C), and the case where even one circuit exceeded 20% was regarded as defective (x). 20% or less were ranked from S to C, but they passed because there was no problem in the product.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示すように、実施例１～２６の金被覆銀ボンディングワイヤによれば、アルミニウムを含む電極とボール圧縮部との接合界面近傍に金濃度がアルミニウムと銀と金の合計に対して５．０原子％以上となる金濃化接合領域が形成できる。そのような接合構造があることにより、ＨＡＳＴ評価が良好となり、高温高湿等の厳しい環境下に長時間さらされても、接続部の比抵抗が上昇しない高い信頼性のある半導体装置を提供できる。表１からの傾向として、金濃化接合領域が接合界面の両端付近にあることが好ましく、また、接合界面において金濃化接合領域がボール圧縮部の幅に対して２５％以上占めることでＨＡＳＴ評価が良好なことが分かる。さらに、ワイヤの芯材にパラジウムやインジウムの添加元素を添加することもＨＡＳＴ評価が良好になる要素のひとつとなる。金濃化接合領域の金濃度に関しても、金濃度が高いほどＨＡＳＴ評価が良くなる傾向にある。どちらかというと金濃度が高いほうが、芯材にパラジウム等を添加するよりもＨＡＳＴ評価に良い影響を与えていると考えられる。 As shown in Table 1, according to the gold-coated silver bonding wires of Examples 1 to 26, the gold concentration in the vicinity of the bonding interface between the electrode containing aluminum and the ball compression portion is 5 with respect to the total of aluminum, silver and gold. A gold-enriched bonding region having a content of 0.0 atomic% or more can be formed. With such a bonding structure, the HAST evaluation is good, and it is possible to provide a highly reliable semiconductor device in which the specific resistance of the connection portion does not increase even when exposed to a harsh environment such as high temperature and high humidity for a long time. .. As a tendency from Table 1, it is preferable that the gold-enriched bonding region is near both ends of the bonding interface, and the gold-concentrated bonding region occupies 25% or more of the width of the ball compression portion at the bonding interface, so that HAST It can be seen that the evaluation is good. Further, adding an additive element of palladium or indium to the core material of the wire is also one of the factors for improving the HAST evaluation. Regarding the gold concentration in the gold-enriched bonding region, the higher the gold concentration, the better the HAST evaluation tends to be. It is considered that a higher gold concentration has a better effect on the HAST evaluation than adding palladium or the like to the core material.
　一方、比較例に示す通り、ワイヤに被覆している金層（表１では濃度換算した値）が２．０質量％未満だと、金濃化接合領域の金濃度が５原子％未満となりＨＡＳＴ評価では不合格となり、反対にワイヤに被覆する金層を厚くしすぎると（ここでは濃度換算して７質量％を超えると）、ＦＡＢ形成時に偏芯等が生じ、ボール形成性が悪くなることが分かる。第１５族元素及び第１６族元素の添加量も重要になる。４質量ｐｐｍ未満だと金濃化接合領域の金濃度が５原子％未満となって、ＨＡＳＴ評価も不合格となり、８０質量ｐｐｍを超えると、今度はワイヤ表面に割れ不良が発生してしまう。もちろん、第１５族及び第１６族元素を添加しない場合も金濃化接合領域が５原子％未満となりＨＡＳＴ評価も不合格となる。 On the other hand, as shown in the comparative example, when the gold layer (concentration-converted value in Table 1) covering the wire is less than 2.0% by mass, the gold concentration in the gold-concentrated bonding region becomes less than 5 atomic% and HAST. The evaluation fails, and conversely, if the gold layer covering the wire is too thick (here, if it exceeds 7% by mass in terms of concentration), eccentricity etc. will occur during FAB formation, and ball formation will deteriorate. I understand. The amount of Group 15 and Group 16 elements added is also important. If it is less than 4 mass ppm, the gold concentration in the gold-enriched bonding region becomes less than 5 atomic%, and the HAST evaluation also fails. If it exceeds 80 mass ppm, crack defects occur on the wire surface. Of course, even when the Group 15 and Group 16 elements are not added, the gold-concentrated bonding region becomes less than 5 atomic%, and the HAST evaluation also fails.
　以上の通り、本発明のワイヤ接合構造及びそれに用いられるボンディングワイヤによれば、ボンディングワイヤの比抵抗の上昇を抑えた上で、電極とボール圧縮部との接合界面近傍に金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域を設けることによって、電極とボール圧縮部との接合信頼性を高めることができる。また、そのようなワイヤ接合構造を適用した本発明の半導体装置によれば、金濃化接合領域による電極とボール圧縮部との接合信頼性、ひいては半導体装置自体の信頼性を向上させることが可能になる。 As described above, according to the wire bonding structure of the present invention and the bonding wire used therein, the concentration of gold is high in the vicinity of the bonding interface between the electrode and the ball compression portion while suppressing an increase in the specific resistance of the bonding wire. By providing a gold-concentrated bonding region of 5 atomic% or more with respect to the total amount of silver and aluminum, the bonding reliability between the electrode and the ball compression portion can be improved. Further, according to the semiconductor device of the present invention to which such a wire bonding structure is applied, it is possible to improve the bonding reliability between the electrode and the ball compression portion by the gold-concentrated bonding region, and eventually the reliability of the semiconductor device itself. become.
　１…ワイヤ接合構造、２…電極、３…金被覆銀ボンディングワイヤ、４…芯材（銀芯材）、５…被覆層、６…ボール圧縮部、７…金濃化接合領域、８…ＦＡＢ（ボール）、９…表面金濃化領域、１０…半導体装置、１１…外部電極、１２…回路基板、１３…チップ電極、１４…半導体チップ、１５…ボンディングワイヤ、１６…ダイボンディング材、１８…封止樹脂層。 1 ... Wire bonding structure, 2 ... Electrode, 3 ... Gold-coated silver bonding wire, 4 ... Core material (silver core material), 5 ... Coating layer, 6 ... Ball compression part, 7 ... Gold-concentrated bonding region, 8 ... FAB (Ball), 9 ... Surface gold-enriched region, 10 ... Semiconductor device, 11 ... External electrode, 12 ... Circuit board, 13 ... Chip electrode, 14 ... Semiconductor chip, 15 ... Bonding wire, 16 ... Die bonding material, 18 ... Encapsulating resin layer.

Claims (7)

  1. 　アルミニウムを含む電極と、ボンディングワイヤと、前記ボンディングワイヤの一端に設けられ、前記電極に接合されたボール圧縮部とを有するワイヤ接合構造であって、
    　前記ボンディングワイヤは、銀を主成分とする芯材と、前記芯材の表面に設けられ、金を主成分とする被覆層とを有し、硫黄、テルル、セレン、ヒ素、及びアンチモンから選ばれる少なくとも１つの第１５及び１６族元素を含有する金被覆銀ボンディングワイヤであって、ワイヤ全体に対して、金濃度が２．０質量％以上７．０質量％以下であり、第１５及び１６族元素濃度が合計で４質量ｐｐｍ以上８０質量ｐｐｍ以下であり、
    　前記電極と前記ボール圧縮部との接合界面近傍に、金濃度が、アルミニウムと銀と金の合計に対して５．０原子％以上となる金濃化接合領域を有する、ワイヤ接合構造。     A wire bonding structure having an electrode containing aluminum, a bonding wire, and a ball compression portion provided at one end of the bonding wire and bonded to the electrode.
    The bonding wire has a core material containing silver as a main component and a coating layer provided on the surface of the core material and containing gold as a main component, and is selected from sulfur, tellurium, selenium, arsenic, and antimony. A gold-coated silver bonding wire containing at least one Group 15 and 16 element, wherein the gold concentration is 2.0% by mass or more and 7.0% by mass or less with respect to the entire wire, and the 15th and 16th groups. The total element concentration is 4% by mass or more and 80% by mass or less.
    A wire bonding structure having a gold-concentrated bonding region in which the gold concentration is 5.0 atomic% or more with respect to the total of aluminum, silver, and gold in the vicinity of the bonding interface between the electrode and the ball compression portion.
  2. 　前記接合界面近傍の金濃化接合領域が、前記ボール圧縮部の最大幅に対して、少なくとも前記ボール圧縮部の両端から１／８の位置の間に各々形成されている、請求項１に記載のワイヤ接合構造。 The first aspect of the present invention, wherein the gold-enriched joint region near the bonding interface is formed at least 1/8 from both ends of the ball compression portion with respect to the maximum width of the ball compression portion. Wire joining structure.
  3. 　前記接合界面近傍の金濃化接合領域の占有率が、前記ボール圧縮部の最大幅に対して、合計で２５％以上である、請求項１又は２に記載のワイヤ接合構造。 The wire bonding structure according to claim 1 or 2, wherein the occupancy rate of the gold-enriched bonding region near the bonding interface is 25% or more in total with respect to the maximum width of the ball compression portion.
  4. 　請求項１ないし請求項３のいずれか１項に記載のワイヤ接続構造に用いられる金被覆銀ボンディングワイヤであって、前記金被覆銀ボンディングワイヤは、銀を主成分として含む芯材と、前記芯材の表面に設けられ、金を主成分として含む被覆層とを有し、
    　前記金被覆銅ボンディングワイヤは、硫黄、テルル、セレン、ヒ素、及びアンチモンから選ばれる少なくとも１つの第１５及び１６族元素を含有し、
    　前記金被覆銅ボンディングワイヤにおいて、ワイヤ全体に対して、金濃度が２．０質量％以上７．０質量％以下であり、第１５及び１６族元素濃度が合計で４質量ｐｐｍ以上８０質量ｐｐｍ以下であり、
    　前記金被覆銀ボンディングワイヤは、アルミニウムを含む電極上にボール接合してボール圧縮部を形成したとき、前記電極と前記ボール圧縮部との接合界面近傍に、金濃度が、アルミニウムと金と銀の合計に対して５．０原子％以上となる金濃化接合領域が形成される、金被覆銅ボンディングワイヤ。     The gold-coated silver bonding wire used in the wire connecting structure according to any one of claims 1 to 3, wherein the gold-coated silver bonding wire includes a core material containing silver as a main component and the core. It is provided on the surface of the material and has a coating layer containing gold as a main component.
    The gold-coated copper bonding wire contains at least one Group 15 and 16 element selected from sulfur, tellurium, selenium, arsenic, and antimony.
    In the gold-coated copper bonding wire, the gold concentration is 2.0% by mass or more and 7.0% by mass or less, and the total concentration of Group 15 and 16 elements is 4% by mass or more and 80% by mass or less with respect to the entire wire. And
    When the gold-coated silver bonding wire is ball-bonded onto an electrode containing aluminum to form a ball compression portion, the gold concentration is as high as that of aluminum, gold, and silver in the vicinity of the bonding interface between the electrode and the ball compression portion. A gold-coated copper bonding wire in which a gold-enriched bonding region having a total of 5.0 atomic% or more is formed.
  5. 　前記金被覆銀ボンディングワイヤの比抵抗が２．３μΩ・ｃｍ以下である、請求項４に記載の金被覆銀ボンディングワイヤ。 The gold-coated silver bonding wire according to claim 4, wherein the specific resistance of the gold-coated silver bonding wire is 2.3 μΩ · cm or less.
  6. 　前記金被覆銀ボンディングワイヤは、パラジウム（Ｐｄ）、白金（Ｐｔ）、金（Ａｕ）、ニッケル（Ｎｉ）、銅（Ｃｕ）、鉄（Ｆｅ）、カルシウム（Ｃａ）、ロジウム（Ｒｈ）、ゲルマニウム（Ｇｅ）、ガリウム（Ｇａ）、及びインジウム（Ｉｎ）から選ばれる少なくとも１つの元素を含む、請求項４又は請求項５に記載の金被覆銀ボンディングワイヤ。 The gold-coated silver bonding wire includes palladium (Pd), platinum (Pt), gold (Au), nickel (Ni), copper (Cu), iron (Fe), calcium (Ca), rhodium (Rh), and germanium (Germanium). The gold-coated silver bonding wire according to claim 4 or 5, which comprises at least one element selected from Ge), gallium (Ga), and indium (In).
  7. 　少なくとも１つのアルミニウムを含む電極を有する１つ又は複数の半導体チップと、
    　リードフレーム又は基板と、
    　前記半導体チップの電極と前記リードフレームとの間、前記半導体チップの電極と前記基板の電極との間、及び前記複数の半導体チップの電極間から選ばれる少なくとも１つを、銀を主成分として含む芯材と、前記芯材の表面に設けられ、金を主成分として含む被覆層とを有するボンディングワイヤで接続した半導体装置であって、
    　前記電極と前記ボンディングワイヤとの接続構造は、前記電極に前記ボンディングワイヤの一端を接合するように設けられたボール圧縮部を備え、前記電極と前記ボール圧縮部との接合界面近傍に、金の濃度が金と銀とアルミニウムの合計量に対して５原子％以上の金濃化接合領域が設けられている、半導体装置。     With one or more semiconductor chips having electrodes containing at least one aluminum
    With the lead frame or board,
    At least one selected from between the electrodes of the semiconductor chip and the lead frame, between the electrodes of the semiconductor chip and the electrodes of the substrate, and between the electrodes of the plurality of semiconductor chips contains silver as a main component. A semiconductor device connected by a bonding wire having a core material and a coating layer provided on the surface of the core material and containing gold as a main component.
    The connection structure between the electrode and the bonding wire includes a ball compression portion provided so as to bond one end of the bonding wire to the electrode, and gold is provided in the vicinity of the bonding interface between the electrode and the ball compression portion. A semiconductor device provided with a gold-concentrated bonding region having a concentration of 5 atomic% or more with respect to the total amount of gold, silver, and aluminum.
PCT/JP2020/010119 2019-10-01 2020-03-09 Wire joining structure, bonding wire used in same, and semiconductor device WO2021065036A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
KR1020227008680A KR20220047621A (en) 2019-10-01 2020-03-09 Wire bonding structure and bonding wire and semiconductor device used therefor
JP2021551112A JP7269361B2 (en) 2019-10-01 2020-03-09 Wire bonding structure, bonding wire and semiconductor device used therefor
DE112020004723.7T DE112020004723T5 (en) 2019-10-01 2020-03-09 Wire bonding structure, bonding wire used therefor and semiconductor device
CN202080064592.7A CN114502754B (en) 2019-10-01 2020-03-09 Wire bonding structure, bonding wire used therein, and semiconductor device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2019181763 2019-10-01
JP2019-181763 2019-10-01

Publications (1)

Publication Number Publication Date
WO2021065036A1 true WO2021065036A1 (en) 2021-04-08

Family

ID=75336861

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2020/010119 WO2021065036A1 (en) 2019-10-01 2020-03-09 Wire joining structure, bonding wire used in same, and semiconductor device

Country Status (6)

Country Link
JP (1) JP7269361B2 (en)
KR (1) KR20220047621A (en)
CN (1) CN114502754B (en)
DE (1) DE112020004723T5 (en)
TW (1) TWI812853B (en)
WO (1) WO2021065036A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023191944A1 (en) * 2022-03-30 2023-10-05 Applied Materials, Inc. Packaging for a sensor and methods of manufacturing thereof
WO2024162232A1 (en) * 2023-01-31 2024-08-08 タツタ電線株式会社 Bonding wire

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
MY197450A (en) 2021-06-25 2023-06-19 Nippon Micrometal Corp Bonding wire for semiconductor devices
WO2022270050A1 (en) * 2021-06-25 2022-12-29 日鉄マイクロメタル株式会社 Bonding wire for semiconductor devices
KR102497492B1 (en) 2021-06-25 2023-02-08 닛데쓰마이크로메탈가부시키가이샤 Bonding wire for semiconductor devices

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6417437A (en) * 1987-07-10 1989-01-20 Kobe Steel Ltd Bonding method for composite bonding wire
JPS6417436A (en) * 1987-07-10 1989-01-20 Kobe Steel Ltd Composite bonding wire
JP2001196411A (en) * 2000-01-11 2001-07-19 Noge Denki Kogyo:Kk Gold-plated silver bonding wire
JP2012169374A (en) * 2011-02-10 2012-09-06 Tanaka Electronics Ind Co Ltd Ag-Au-Pd TERNARY ALLOY BASED BONDING WIRE
JP2014222725A (en) * 2013-05-14 2014-11-27 田中電子工業株式会社 Bonding wire for high-speed signal
JP2016029691A (en) * 2014-07-25 2016-03-03 田中電子工業株式会社 Structure of surface property-modified silver palladium alloy wire
WO2017187653A1 (en) * 2016-04-28 2017-11-02 日鉄住金マイクロメタル株式会社 Bonding wire for semiconductor devices

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3673368B2 (en) 1997-05-23 2005-07-20 新日本製鐵株式会社 Gold-silver alloy fine wire for semiconductor devices
JP2001096411A (en) 1999-09-28 2001-04-10 Hitachi Tool Engineering Ltd Twist drill
US9740442B2 (en) 2010-12-21 2017-08-22 Sato Holdings Kabushiki Kaisha Virtual input/output device for printers
US9059003B2 (en) 2012-02-27 2015-06-16 Nippon Micrometal Corporation Power semiconductor device, method of manufacturing the device and bonding wire
US20130241058A1 (en) * 2012-03-16 2013-09-19 Taiwan Semiconductor Manufacturing Company, Ltd. Wire Bonding Structures for Integrated Circuits
JP5529992B1 (en) * 2013-03-14 2014-06-25 タツタ電線株式会社 Bonding wire
JP2015162617A (en) * 2014-02-28 2015-09-07 サンケン電気株式会社 semiconductor device
WO2016189752A1 (en) * 2015-05-26 2016-12-01 日鉄住金マイクロメタル株式会社 Bonding wire for semiconductor device
MY162048A (en) * 2015-06-15 2017-05-31 Nippon Micrometal Corp Bonding wire for semiconductor device
KR101659254B1 (en) * 2015-07-23 2016-09-22 닛데쓰스미킹 마이크로 메탈 가부시키가이샤 Bonding wire for semiconductor device
KR101812943B1 (en) * 2016-10-20 2017-12-28 엠케이전자 주식회사 Bonding wire
JP6869920B2 (en) 2018-04-02 2021-05-12 田中電子工業株式会社 Precious metal-coated silver wire for ball bonding and its manufacturing method, and semiconductor device using precious metal-coated silver wire for ball bonding and its manufacturing method
JP6869919B2 (en) 2018-04-02 2021-05-12 田中電子工業株式会社 Precious metal-coated silver wire for ball bonding and its manufacturing method, and semiconductor device using precious metal-coated silver wire for ball bonding and its manufacturing method
JP6487108B1 (en) 2018-11-26 2019-03-20 田中電子工業株式会社 Palladium-coated copper bonding wire and manufacturing method thereof
JP6507329B1 (en) 2019-02-08 2019-04-24 田中電子工業株式会社 Palladium-coated copper bonding wire, wire bonding structure, semiconductor device, and method of manufacturing semiconductor device

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6417437A (en) * 1987-07-10 1989-01-20 Kobe Steel Ltd Bonding method for composite bonding wire
JPS6417436A (en) * 1987-07-10 1989-01-20 Kobe Steel Ltd Composite bonding wire
JP2001196411A (en) * 2000-01-11 2001-07-19 Noge Denki Kogyo:Kk Gold-plated silver bonding wire
JP2012169374A (en) * 2011-02-10 2012-09-06 Tanaka Electronics Ind Co Ltd Ag-Au-Pd TERNARY ALLOY BASED BONDING WIRE
JP2014222725A (en) * 2013-05-14 2014-11-27 田中電子工業株式会社 Bonding wire for high-speed signal
JP2016029691A (en) * 2014-07-25 2016-03-03 田中電子工業株式会社 Structure of surface property-modified silver palladium alloy wire
WO2017187653A1 (en) * 2016-04-28 2017-11-02 日鉄住金マイクロメタル株式会社 Bonding wire for semiconductor devices

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023191944A1 (en) * 2022-03-30 2023-10-05 Applied Materials, Inc. Packaging for a sensor and methods of manufacturing thereof
WO2024162232A1 (en) * 2023-01-31 2024-08-08 タツタ電線株式会社 Bonding wire

Also Published As

Publication number Publication date
JPWO2021065036A1 (en) 2021-04-08
DE112020004723T5 (en) 2022-06-15
JP7269361B2 (en) 2023-05-08
KR20220047621A (en) 2022-04-18
TW202115799A (en) 2021-04-16
CN114502754A (en) 2022-05-13
TWI812853B (en) 2023-08-21
CN114502754B (en) 2023-11-17

Similar Documents

Publication Publication Date Title
WO2021065036A1 (en) Wire joining structure, bonding wire used in same, and semiconductor device
KR101280668B1 (en) Bonding structure of bonding wire and method for forming the bonding structure
JP6807426B2 (en) Gold-coated silver bonding wire and its manufacturing method, and semiconductor device and its manufacturing method
JP6507329B1 (en) Palladium-coated copper bonding wire, wire bonding structure, semiconductor device, and method of manufacturing semiconductor device
WO2020246094A1 (en) Palladium-coated copper bonding wire, method for producing palladium-coated copper bonding wire, semiconductor device using same, and method for producing same
TWI761637B (en) Palladium-coated copper bonding wire and method for producing the same
JP7168760B2 (en) Palladium-coated copper bonding wire, method for producing palladium-coated copper bonding wire, wire bonding structure using the same, semiconductor device, and method for producing the same
JP6869920B2 (en) Precious metal-coated silver wire for ball bonding and its manufacturing method, and semiconductor device using precious metal-coated silver wire for ball bonding and its manufacturing method
JP6869919B2 (en) Precious metal-coated silver wire for ball bonding and its manufacturing method, and semiconductor device using precious metal-coated silver wire for ball bonding and its manufacturing method
CN113169077B (en) Palladium-covered copper bonding wire and method for manufacturing same

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20872371

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2021551112

Country of ref document: JP

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 20227008680

Country of ref document: KR

Kind code of ref document: A

122 Ep: pct application non-entry in european phase

Ref document number: 20872371

Country of ref document: EP

Kind code of ref document: A1