WO2014048449A1 - Electronic device and method for forming an electrical connection - Google Patents

Electronic device and method for forming an electrical connection Download PDF

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Publication number
WO2014048449A1
WO2014048449A1 PCT/EP2012/068854 EP2012068854W WO2014048449A1 WO 2014048449 A1 WO2014048449 A1 WO 2014048449A1 EP 2012068854 W EP2012068854 W EP 2012068854W WO 2014048449 A1 WO2014048449 A1 WO 2014048449A1
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WO
WIPO (PCT)
Prior art keywords
bond
contact area
ball
wire
connection
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/EP2012/068854
Other languages
French (fr)
Inventor
Lay Ting CHUA
Wei Chin KHAW
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ams Osram International GmbH
Original Assignee
Osram Opto Semiconductors GmbH
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 Osram Opto Semiconductors GmbH filed Critical Osram Opto Semiconductors GmbH
Priority to PCT/EP2012/068854 priority Critical patent/WO2014048449A1/en
Publication of WO2014048449A1 publication Critical patent/WO2014048449A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/071—Connecting or disconnecting
    • H10W72/075—Connecting or disconnecting of bond wires
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/01—Manufacture or treatment
    • H10W72/015—Manufacture or treatment of bond wires
    • H10W72/01551—Changing the shapes of bond wires
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/071—Connecting or disconnecting
    • H10W72/0711—Apparatus therefor
    • H10W72/07141—Means for applying energy, e.g. ovens or lasers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/071—Connecting or disconnecting
    • H10W72/075—Connecting or disconnecting of bond wires
    • H10W72/07502—Connecting or disconnecting of bond wires using an auxiliary member
    • H10W72/07504—Connecting or disconnecting of bond wires using an auxiliary member the auxiliary member being temporary, e.g. a sacrificial coating
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/071—Connecting or disconnecting
    • H10W72/075—Connecting or disconnecting of bond wires
    • H10W72/07511—Treating the bonding area before connecting, e.g. by applying flux or cleaning
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/071—Connecting or disconnecting
    • H10W72/075—Connecting or disconnecting of bond wires
    • H10W72/07521—Aligning
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/071—Connecting or disconnecting
    • H10W72/075—Connecting or disconnecting of bond wires
    • H10W72/07531—Techniques
    • H10W72/07532—Compression bonding, e.g. thermocompression bonding
    • H10W72/07533—Ultrasonic bonding, e.g. thermosonic bonding
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/071—Connecting or disconnecting
    • H10W72/075—Connecting or disconnecting of bond wires
    • H10W72/07551—Connecting or disconnecting of bond wires characterised by changes in properties of the bond wires during the connecting
    • H10W72/07553—Connecting or disconnecting of bond wires characterised by changes in properties of the bond wires during the connecting changes in shapes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/50—Bond wires
    • H10W72/531—Shapes of wire connectors
    • H10W72/536—Shapes of wire connectors the connected ends being ball-shaped
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/50—Bond wires
    • H10W72/531—Shapes of wire connectors
    • H10W72/5363—Shapes of wire connectors the connected ends being wedge-shaped
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/50—Bond wires
    • H10W72/531—Shapes of wire connectors
    • H10W72/5366—Shapes of wire connectors the bond wires having kinks
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/50—Bond wires
    • H10W72/541—Dispositions of bond wires
    • H10W72/5434—Dispositions of bond wires the connected ends being on auxiliary connecting means on bond pads, e.g. on other bond wires
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/50—Bond wires
    • H10W72/551—Materials of bond wires
    • H10W72/552—Materials of bond wires comprising metals or metalloids, e.g. silver
    • H10W72/5522—Materials of bond wires comprising metals or metalloids, e.g. silver comprising gold [Au]
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/50—Bond wires
    • H10W72/551—Materials of bond wires
    • H10W72/552—Materials of bond wires comprising metals or metalloids, e.g. silver
    • H10W72/5524—Materials of bond wires comprising metals or metalloids, e.g. silver comprising aluminium [Al]
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/50—Bond wires
    • H10W72/551—Materials of bond wires
    • H10W72/552—Materials of bond wires comprising metals or metalloids, e.g. silver
    • H10W72/5525—Materials of bond wires comprising metals or metalloids, e.g. silver comprising copper [Cu]
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/50—Bond wires
    • H10W72/59—Bond pads specially adapted therefor
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00—Interconnections or connectors in packages
    • H10W72/90—Bond pads, in general
    • H10W72/951—Materials of bond pads
    • H10W72/952—Materials of bond pads comprising metals or metalloids, e.g. PbSn, Ag or Cu
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W90/00—Package configurations
    • H10W90/701—Package configurations characterised by the relative positions of pads or connectors relative to package parts
    • H10W90/751—Package configurations characterised by the relative positions of pads or connectors relative to package parts of bond wires
    • H10W90/754—Package configurations characterised by the relative positions of pads or connectors relative to package parts of bond wires between a chip and a stacked insulating package substrate, interposer or RDL
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W90/00—Package configurations
    • H10W90/701—Package configurations characterised by the relative positions of pads or connectors relative to package parts
    • H10W90/751—Package configurations characterised by the relative positions of pads or connectors relative to package parts of bond wires
    • H10W90/756—Package configurations characterised by the relative positions of pads or connectors relative to package parts of bond wires between a chip and a stacked lead frame, conducting package substrate or heat sink

Definitions

  • the present application relates to an electronic device and to a method for forming an electrical connection.
  • Electronic components such as semiconductor chips may be electrically connected by means of wire bonding, for example.
  • Mechanical stress for instance, may result in a breakage of the bond connection, which in turn typically leads to failure of the component.
  • the reliability of a wire bond connection may be reduced if the loop height needs to be reduced due to space constraints.
  • One object to be solved is to specify an electronic device that exhibits a highly reliable connection.
  • a further object is to specify a method that allows for providing a highly reliable electrical connection.
  • the electronic device comprises a first contact area.
  • the first contact area may be an area provided on a first contact area.
  • semiconductor chip said area being intended for external electrical connection of the semiconductor chip.
  • the term “electronic device” includes electronic devices such as diodes or transistors as well as optoelectronic devices.
  • the electronic device may comprise at least one optoelectronic semiconductor chip such as a luminescence diode or a radiation detector.
  • the term “wire bond connections” includes all types of connections that use a bond wire.
  • the wire bond connection may be formed by any kind of wire bonding, for instance by ball bonding. Heat, pressure or ultrasonic energy as well as combinations thereof may be applied during fabrication of the wire bond connection.
  • the electronic device comprises a second contact area.
  • the second contact area may be an area provided on a submount of a semiconductor chip, on a lead frame or on a connection carrier such as a printed circuit board.
  • the second contact area may be provided on a semiconductor chip, said area being intended for external electrical connection of the semiconductor chip.
  • a wire bond connection is formed between the first contact area and the second contact area.
  • the wire bond connection electrically conductively connects the first contact area with the second contact area.
  • the wire bond connection extends between a first end of the wire bond connection and a second end of the wire bond connection.
  • a wire part of the wire bond connection extends between the first end and the second end.
  • a cross section of the wire part is constant along the wire bond connection.
  • the cross section of the wire part is of circular shape .
  • the first end is a bond ball.
  • the second end preferably is a wedge bond.
  • the wedge bond is formed without making a bond ball.
  • the wedge bond is also referred to as tail bond or as second bond.
  • the term wedge bond does not necessarily imply that the shape of the second end is of a geometric wedge shape.
  • an additional bond ball is arranged on top of the wire bond connection.
  • the additional bond ball may be
  • the wire part preferably extends beyond the additional bond ball.
  • a main plane of extension of the first contact area is arranged in an elevated manner with respect to a main plane of extension of the second contact area, so that the wire bond connection extends only on a side of the main plane of extension of the second contact area that faces the first contact area.
  • the first contact area is arranged on a higher level than the second contact area.
  • the first and second contact areas may be arranged on an equal level.
  • the first contact area is a bond pad of a
  • the second contact area may be a bond pad of a semiconductor chip.
  • the additional bond ball is arranged on top of the first contact area.
  • the additional bond ball is formed on top of the wedge bond.
  • the wedge bond is arranged between the additional bond ball and the contact area on which the wedge bond is arranged .
  • the additional bond ball is formed on top of the bond ball.
  • the bond ball is arranged between the additional bond ball and the contact area on which the bond ball is arranged.
  • a maximum extension of the additional bond ball may be smaller than a maximum extension of the bond ball.
  • the diameter of the additional bond ball is smaller than the diameter of the bond ball.
  • the first end is a bond ball, said bond ball being arranged on the first contact area, wherein the first contact area preferably is arranged in an elevated manner with respect to the second contact area and wherein the additional bond ball is arranged on top of the bond ball.
  • the second end is a wedge bond, said wedge bond being arranged on the first contact area, wherein the first contact area preferably is arranged in an elevated manner with respect to the second contact area and wherein the additional bond ball is formed on the wedge bond.
  • an underlying bond ball is arranged between the wedge bond and the contact area on which the wedge bond is
  • the wedge bond may be arranged between the underlying bond ball and the additional bond ball.
  • a wedged part of the wedge bond overlaps a center of the underlying bond ball in top view.
  • a center of the wedge bond is offset with respect to a center of the underlying bond ball.
  • the height of the wire bond connection decreases as seen from the wire part towards the wedge bond.
  • a first contact area and a second contact area are provided.
  • a wire bond connection is formed between the first contact area and the second contact area, wherein the wire bond connection extends between a first end and a second end.
  • an additional bond ball is formed on top of the wire bond connection. By means of the additional bond ball, the wire bond connection formed prior to the formation of the
  • the additional bond ball is thinned or removed after its
  • a kink is formed in the wire bond connection.
  • the kink may overlap the first contact area in top view. This means that the wire part may extend vertically or
  • the additional bond ball may be formed on top of the kink. Using the additional bond ball, the wire extending between the first end and the kink is compressed, so that the vertical extension of the wire bond connection may be reduced.
  • Figures 1A through ID show method steps of an exemplary embodiment of the method for forming an electrical connection in an electronic device, wherein Figure 1C represents an exemplary embodiment of the electronic device.
  • Figure ID a magnified representation of a section of Figure IB is depicted .
  • Figures 2A through 2C show method steps of a further
  • a first contact area 21 and a second contact area 22 are provided.
  • the first contact area is a bond pad of a semiconductor chip 6.
  • the bond pad is provided for an external electrical connection of the semiconductor chip via a wire bonding connection.
  • wire bonding includes all types of bond connections that use a bond wire, for instance ball bonding.
  • other metals such as aluminum, silver, copper or tin, may be used alternatively or in addition.
  • the semiconductor chip 6 is mounted on a further contact area 23.
  • the further contact area 23 and the second contact area 22 are provided on a surface of a carrier 7.
  • the carrier may be a submount or a printed circuit board, for instance.
  • the carrier 7 may be a lead frame which provides the first contact area 21 and the second contact area 22.
  • the first contact area 21 is vertically spaced apart from the second contact area 22.
  • a vertical direction is understood to be a direction running perpendicularly with respect to a main plane 210 of extension of the first contact area 21.
  • the first contact area 21 is arranged in an elevated manner with respect to a main plane of extension 220 of the second contact area 22.
  • a distance between the carrier 5 and the first contact area 21 is larger than a distance between the carrier 5 and the second contact area 22.
  • the wire bond connection 3 extends on only one side of the second contact area 22 that faces the first contact area.
  • the wire bond connection 3 comprises a region that extends away from the second contact area 22 and a region that extends towards the second contact area 21.
  • An underlying ball 5 is formed on the first contact area 21. In particular, the underlying ball is in direct physical contact with the first contact area. In top view, the
  • underlying ball 5 is arranged entirely within the first contact area 21, so that the underlying ball does not extend beyond the first contact area in a lateral direction.
  • a wire bond connection 3 is formed between the first contact area 21 and the second contact area 22.
  • the wire bond connection 3 extends between a first end 31 and a second end 32.
  • the second contact area 22 is connected first. Subsequently, the first contact area 21 is provided with the second end 32 of the wire bond connection.
  • the wire bond connection 3 further comprises a wire part 35 extending between the first end 31 and the second end 32.
  • the wire part 35 comprises a kink 36. By means of the kink 36, the wire part 35 is divided into a region extending
  • the first end 31 is a bond ball and the second end 32 is a wedge bond.
  • the wedge bond is formed by pressing the wire of the wire bond connection 3 against the underlying bond ball 5 so that the first end 31 comprises a flat part 33 and a wedged part 34.
  • ultrasonic energy is applied with a transducer during formation of the wedge bond.
  • the formation of the wedge bond is shown in Figure ID in more detail.
  • the second end 32 is formed such that the wedged part
  • an additional bond ball 4 is formed on top of the wire bond connection 3 ( Figure 1C) .
  • the additional bond ball By means of the additional bond ball, the mechanical strength of the wire bond connection 3 is improved. In particular, the connection between the second end 32 and the underlying bond ball 5 is enhanced.
  • the diameter of the additional bond ball 4 is preferably smaller than the diameter of the underlying bond ball 5. This helps to reduce the overall bump height on top of the first contact area 21. Simulations have shown that the maximum mechanical stress occurs in the wedged part 34 of the wire bond connection 3. As the additional bond ball 4 covers the wedged part 34, the risk of a wire breakage at the position of the wedged part 34 may be avoided or at least significantly reduced.
  • the wire bond connection comprises gold or consists of gold.
  • the wire bond connection may comprise some other metal, for instance aluminum or copper or a metallic alloy comprising at least one of said materials.
  • the underlying bond ball 5 may also be dispensed with.
  • the second end 32 may be in direct physical contact with the first contact area 21.
  • the semiconductor chip 6 may be an electronic chip such as a transistor or a diode or an optoelectronic chip.
  • the optoelectronic semiconductor chip 6 may be a luminescence diode chip, such as a light emitting diode chip, or a laser diode chip.
  • the semiconductor chip 6 may also be a radiation detector, such as a photodiode.
  • the diameter of the wire used for the fabrication of the wire bond connection 3 preferably is between 30 ym, inclusively, and 60 ym, inclusively. Thinner wires may be used as well in order to further reduce the device height. However, the current that may be fed through a thin wire is restricted, so that thin wires are not suitable for high-power applications. Of course, thicker wires may also be used. However, thicker wires may result in an increased vertical extension of the wire bond connection 3.
  • the loop height of the wire bond connection 3 preferably is less than 100 ym.
  • the loop height is the maximum vertical extension of the wire bond connection with respect to the level of the elevated contact area. For instance, with a wire of 38 ym in diameter, a loop height of between 60 ym,
  • FIG. 2A through 2C A further exemplary embodiment for a method for forming an electrical connection is shown in Figures 2A through 2C, wherein Figure 2C shows a finished electronic device according to a further exemplary embodiment.
  • the method and the device essentially correspond to the previously described first embodiments for a method and a device, respectively.
  • the wire bond connection 3 is produced such that the first end 31 is formed on the first contact area 21 and the second end 32 is formed on the second contact area 22.
  • the wire part 35 extends vertically to a kink 36 of the wire bond connection 3.
  • the kink 36 overlaps the first contact area 21 in top view.
  • an additional bond ball 4 is formed on top of the kink 36 so that the wire part extending between the first end and the kink 36 is compressed.
  • Arrow 8 is formed on top of the kink 36 so that the wire part extending between the first end and the kink 36 is compressed.
  • the size of the additional bond ball 4 is smaller than the size of the bond ball of the first end 31, so that the height of the bond bump formed on the first contact area 21 may be kept small.
  • part of the additional bond ball 4 or even the entire additional bond ball 4 may be removed. This may be done mechanically, for instance. It has turned out that, even if the additional bond ball 4 is not present in the finished electronic device, the reliability of the wire bond connection 3 may be improved. However, the additional bond ball 4 may also remain in the finished device. Even with the additional bond ball 4 remaining in the device, the overall bump height formed on the first contact 21 may be smaller than 80 ym, for instance between 40 ym and 70 ym.
  • the methods described allow for producing electronic devices having a wire bond connection that is highly reliable and at the same time of reduced vertical extension. This allows for reducing the overall height of the electronic device.
  • the additional bond ball 4 is formed on the contact area which is elevated with respect to the second contact area. It has turned out that the end of the wire bond connection 3 that is arranged on the elevated contact area, i.e. the first contact area 21 in the exemplary embodiments, may be significantly strengthened by means of the additional bond ball 4, irrespective of whether the end of the wire bond connection is the first end 31 or the second end 32. However, the method is also suitable for making electrical connections between contact areas being arranged on an equal level.
  • a further additional bond ball may be arranged on the second contact area 22, so that both ends of the wire bond connection 3 are provided with an additional bond ball.

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  • Wire Bonding (AREA)

Abstract

An electronic device (1) comprising a first contact area (21), a second contact area (22) and a wire bond connection (3) between the first contact area and the second contact area is specified. The wire bond connection extends between a first end (31) of the wire bond connection and a second end (32) of the wire bond connection, wherein an additional bond ball (4) is arranged on top of the wire bond connection. Furthermore, a method for forming an electrical connection is specified.

Description

Description
Electronic device and method for forming an electrical connection
The present application relates to an electronic device and to a method for forming an electrical connection.
Electronic components such as semiconductor chips may be electrically connected by means of wire bonding, for example. Mechanical stress, for instance, may result in a breakage of the bond connection, which in turn typically leads to failure of the component. In particular, the reliability of a wire bond connection may be reduced if the loop height needs to be reduced due to space constraints.
One object to be solved is to specify an electronic device that exhibits a highly reliable connection. A further object is to specify a method that allows for providing a highly reliable electrical connection.
In accordance with at least one aspect of the electronic device, the electronic device comprises a first contact area. The first contact area may be an area provided on a
semiconductor chip, said area being intended for external electrical connection of the semiconductor chip.
The term "electronic device" includes electronic devices such as diodes or transistors as well as optoelectronic devices. For instance, the electronic device may comprise at least one optoelectronic semiconductor chip such as a luminescence diode or a radiation detector. The term "wire bond connections" includes all types of connections that use a bond wire. The wire bond connection may be formed by any kind of wire bonding, for instance by ball bonding. Heat, pressure or ultrasonic energy as well as combinations thereof may be applied during fabrication of the wire bond connection.
In accordance with at least one aspect of the electronic device, the electronic device comprises a second contact area. The second contact area may be an area provided on a submount of a semiconductor chip, on a lead frame or on a connection carrier such as a printed circuit board.
Alternatively, the second contact area may be provided on a semiconductor chip, said area being intended for external electrical connection of the semiconductor chip.
In accordance with at least one aspect of the electronic device, a wire bond connection is formed between the first contact area and the second contact area. The wire bond connection electrically conductively connects the first contact area with the second contact area. The wire bond connection extends between a first end of the wire bond connection and a second end of the wire bond connection.
A wire part of the wire bond connection extends between the first end and the second end. Preferably, a cross section of the wire part is constant along the wire bond connection. In particular, the cross section of the wire part is of circular shape . Preferably, the first end is a bond ball. The second end preferably is a wedge bond. The wedge bond is formed without making a bond ball. The wedge bond is also referred to as tail bond or as second bond. The term wedge bond does not necessarily imply that the shape of the second end is of a geometric wedge shape. During production of the wedge bond, pressure is applied on the bond wire, so that the wire is compressed. For instance, the wire may be crushed between a capillary the wire is fed in and the surface to be bonded. Compared to the wire part, the height of the wedge bond is decreased and a lateral extension of the wedge bond is increased. It has turned out that the additional bond ball arranged on top of the bond ball or on top of the wedge bond improves the reliability of the wire bond connection.
In accordance with at least one aspect of the electronic device, an additional bond ball is arranged on top of the wire bond connection. The additional bond ball may be
provided on top of the first end or on top of the second end of the wire bond connection. The wire part preferably extends beyond the additional bond ball.
In accordance with at least one aspect of the electronic device, a main plane of extension of the first contact area is arranged in an elevated manner with respect to a main plane of extension of the second contact area, so that the wire bond connection extends only on a side of the main plane of extension of the second contact area that faces the first contact area. In other words, the first contact area is arranged on a higher level than the second contact area.
Alternatively, the first and second contact areas may be arranged on an equal level. In accordance with at least one aspect of the electronic device, the first contact area is a bond pad of a
semiconductor chip. Alternatively or in addition, the second contact area may be a bond pad of a semiconductor chip. In accordance with at least one aspect of the electronic device, the additional bond ball is arranged on top of the first contact area. By means of the additional bond ball, a highly reliable wire bond connection having a low loop height may be obtained in a simplified manner.
In accordance with at least one aspect of the electronic device, the additional bond ball is formed on top of the wedge bond. The wedge bond is arranged between the additional bond ball and the contact area on which the wedge bond is arranged .
In accordance with at least one aspect of the electronic device, the additional bond ball is formed on top of the bond ball. The bond ball is arranged between the additional bond ball and the contact area on which the bond ball is arranged. In particular, a maximum extension of the additional bond ball may be smaller than a maximum extension of the bond ball. During production, the diameter of the additional bond ball is smaller than the diameter of the bond ball. Using an additional bond ball of reduced diameter allows for reducing the overall height of the wire bond connection without negatively affecting the reliability of the wire bond
connection .
In accordance with at least one aspect of the electronic device, the first end is a bond ball, said bond ball being arranged on the first contact area, wherein the first contact area preferably is arranged in an elevated manner with respect to the second contact area and wherein the additional bond ball is arranged on top of the bond ball. In accordance with at least one aspect of the electronic device, the second end is a wedge bond, said wedge bond being arranged on the first contact area, wherein the first contact area preferably is arranged in an elevated manner with respect to the second contact area and wherein the additional bond ball is formed on the wedge bond.
In accordance with at least one aspect of the electronic device, an underlying bond ball is arranged between the wedge bond and the contact area on which the wedge bond is
arranged, for instance on the first contact area. By means of the underlying bond ball, a mechanically stable connection between the contact area and the wedge bond may be obtained in a simplified manner. In particular, the wedge bond may be arranged between the underlying bond ball and the additional bond ball.
In accordance with at least one aspect of the electronic device, a wedged part of the wedge bond overlaps a center of the underlying bond ball in top view. In other words, a center of the wedge bond is offset with respect to a center of the underlying bond ball. In the wedged part, the height of the wire bond connection decreases as seen from the wire part towards the wedge bond. The additional bond ball
preferably covers the center of the underlying bond ball.
In accordance with at least one aspect of the method, a first contact area and a second contact area are provided. A wire bond connection is formed between the first contact area and the second contact area, wherein the wire bond connection extends between a first end and a second end. In accordance with at least one aspect of the method, an additional bond ball is formed on top of the wire bond connection. By means of the additional bond ball, the wire bond connection formed prior to the formation of the
additional bond ball is pressed against the contact area on which the additional bond ball is formed.
In accordance with at least one aspect of the method, the additional bond ball is thinned or removed after its
formation. By means of this step, the overall height of the wire bond connection above the contact area may be reduced. Alternatively, the additional bond ball may entirely remain on the contact area. In accordance with at least one aspect of the method, a kink is formed in the wire bond connection. In particular, the kink may overlap the first contact area in top view. This means that the wire part may extend vertically or
substantially vertically with respect to the first contact area from the first end to the kink. The additional bond ball may be formed on top of the kink. Using the additional bond ball, the wire extending between the first end and the kink is compressed, so that the vertical extension of the wire bond connection may be reduced.
The method described is particularly suited for the
production of the electronic device. Thus, features described in connection with the device may also apply to the method and vice versa.
The device and the method for forming an electrical
connection are described in greater detail below on the basis of exemplary embodiments and the corresponding figures. In the figures:
Figures 1A through ID show method steps of an exemplary embodiment of the method for forming an electrical connection in an electronic device, wherein Figure 1C represents an exemplary embodiment of the electronic device. In Figure ID, a magnified representation of a section of Figure IB is depicted . Figures 2A through 2C show method steps of a further
exemplary embodiment of the method for forming an electrical connection in an electronic device, wherein Figure 2C
represents a further exemplary embodiment of the electronic device .
Elements which are identical, of identical type or act identically are marked with the same reference symbols in the figures . The figures and the proportions of the individual elements illustrated in the figures should not be regarded as drawn to scale. Rather, individual elements - for example layer thicknesses - may be illustrated in an exaggerated size in order to allow for better demonstration and/or a better understanding.
An exemplary embodiment for a method for forming an
electrical connection is shown in Figures 1A through ID in sectional view, wherein Figure 1C shows an exemplary
embodiment of an electronic device.
As shown in Figure 1A, a first contact area 21 and a second contact area 22 are provided. The first contact area is a bond pad of a semiconductor chip 6. The bond pad is provided for an external electrical connection of the semiconductor chip via a wire bonding connection. The term "wire bonding" includes all types of bond connections that use a bond wire, for instance ball bonding.
The first contact area 21 and the second contact area
preferably comprise gold. However, other metals, such as aluminum, silver, copper or tin, may be used alternatively or in addition.
The semiconductor chip 6 is mounted on a further contact area 23. The further contact area 23 and the second contact area 22 are provided on a surface of a carrier 7. The carrier may be a submount or a printed circuit board, for instance. Unlike in the present embodiment, the carrier 7 may be a lead frame which provides the first contact area 21 and the second contact area 22.
The first contact area 21 is vertically spaced apart from the second contact area 22. A vertical direction is understood to be a direction running perpendicularly with respect to a main plane 210 of extension of the first contact area 21. The first contact area 21 is arranged in an elevated manner with respect to a main plane of extension 220 of the second contact area 22. In other words, a distance between the carrier 5 and the first contact area 21 is larger than a distance between the carrier 5 and the second contact area 22. This means that the wire bond connection 3 extends on only one side of the second contact area 22 that faces the first contact area. As seen from the first contact area, the wire bond connection 3 comprises a region that extends away from the second contact area 22 and a region that extends towards the second contact area 21. An underlying ball 5 is formed on the first contact area 21. In particular, the underlying ball is in direct physical contact with the first contact area. In top view, the
underlying ball 5 is arranged entirely within the first contact area 21, so that the underlying ball does not extend beyond the first contact area in a lateral direction.
As shown in Figure IB, a wire bond connection 3 is formed between the first contact area 21 and the second contact area 22. The wire bond connection 3 extends between a first end 31 and a second end 32. The second contact area 22 is connected first. Subsequently, the first contact area 21 is provided with the second end 32 of the wire bond connection.
The wire bond connection 3 further comprises a wire part 35 extending between the first end 31 and the second end 32. The wire part 35 comprises a kink 36. By means of the kink 36, the wire part 35 is divided into a region extending
essentially parallel to the vertical direction between the first end 31 and the kink 36 and a further region running perpendicularly or essentially perpendicularly with respect to the vertical direction. The kink 36 may help to reduce the overall vertical extension of the wire bond connection 3. However, the kink may also be dispensed with. In the embodiment shown, the first end 31 is a bond ball and the second end 32 is a wedge bond. The wedge bond is formed by pressing the wire of the wire bond connection 3 against the underlying bond ball 5 so that the first end 31 comprises a flat part 33 and a wedged part 34. Preferably, ultrasonic energy is applied with a transducer during formation of the wedge bond. The formation of the wedge bond is shown in Figure ID in more detail. The second end 32 is formed such that the wedged part
34 which extends between the flat part 33 and the wire part
35 overlaps a center of the underlying bond ball 5. In Figure ID, a center line 51 running through the center of the underlying bond ball 5 is shown.
Subsequently, an additional bond ball 4 is formed on top of the wire bond connection 3 (Figure 1C) . By means of the additional bond ball, the mechanical strength of the wire bond connection 3 is improved. In particular, the connection between the second end 32 and the underlying bond ball 5 is enhanced. The diameter of the additional bond ball 4 is preferably smaller than the diameter of the underlying bond ball 5. This helps to reduce the overall bump height on top of the first contact area 21. Simulations have shown that the maximum mechanical stress occurs in the wedged part 34 of the wire bond connection 3. As the additional bond ball 4 covers the wedged part 34, the risk of a wire breakage at the position of the wedged part 34 may be avoided or at least significantly reduced.
Preferably, the wire bond connection comprises gold or consists of gold. Alternatively, the wire bond connection may comprise some other metal, for instance aluminum or copper or a metallic alloy comprising at least one of said materials.
Unlike in the exemplary embodiment shown, the underlying bond ball 5 may also be dispensed with. In this case, the second end 32 may be in direct physical contact with the first contact area 21.
A finished electronic device 1 according to a first exemplary embodiment is shown in Figure 1C. The semiconductor chip 6 may be an electronic chip such as a transistor or a diode or an optoelectronic chip. For instance, the optoelectronic semiconductor chip 6 may be a luminescence diode chip, such as a light emitting diode chip, or a laser diode chip. The semiconductor chip 6 may also be a radiation detector, such as a photodiode.
The diameter of the wire used for the fabrication of the wire bond connection 3 preferably is between 30 ym, inclusively, and 60 ym, inclusively. Thinner wires may be used as well in order to further reduce the device height. However, the current that may be fed through a thin wire is restricted, so that thin wires are not suitable for high-power applications. Of course, thicker wires may also be used. However, thicker wires may result in an increased vertical extension of the wire bond connection 3.
The loop height of the wire bond connection 3 preferably is less than 100 ym. The loop height is the maximum vertical extension of the wire bond connection with respect to the level of the elevated contact area. For instance, with a wire of 38 ym in diameter, a loop height of between 60 ym,
inclusively, and 100 ym, inclusively, may be obtained.
A further exemplary embodiment for a method for forming an electrical connection is shown in Figures 2A through 2C, wherein Figure 2C shows a finished electronic device according to a further exemplary embodiment. The method and the device essentially correspond to the previously described first embodiments for a method and a device, respectively. Unlike in the first embodiment, the wire bond connection 3 is produced such that the first end 31 is formed on the first contact area 21 and the second end 32 is formed on the second contact area 22. Starting from the first contact area 21, the wire part 35 extends vertically to a kink 36 of the wire bond connection 3. The kink 36 overlaps the first contact area 21 in top view.
As shown in Figure 2B, an additional bond ball 4 is formed on top of the kink 36 so that the wire part extending between the first end and the kink 36 is compressed. Arrow 8
indicates the direction of movement during fabrication of the additional bond ball 4.
It has turned out that such a wire bond connection with the kink 36 being pressed into the bond ball of the first end 31 has an improved reliability as compared to a wire bond connection having a sharp kink slightly above the bond ball of the first end 31. Furthermore, the overall vertical extension of the wire bond connection 3 may be reduced by means of the additional bond ball 4.
Preferably, the size of the additional bond ball 4 is smaller than the size of the bond ball of the first end 31, so that the height of the bond bump formed on the first contact area 21 may be kept small.
In order to further reduce the overall height, part of the additional bond ball 4 or even the entire additional bond ball 4 may be removed. This may be done mechanically, for instance. It has turned out that, even if the additional bond ball 4 is not present in the finished electronic device, the reliability of the wire bond connection 3 may be improved. However, the additional bond ball 4 may also remain in the finished device. Even with the additional bond ball 4 remaining in the device, the overall bump height formed on the first contact 21 may be smaller than 80 ym, for instance between 40 ym and 70 ym. The methods described allow for producing electronic devices having a wire bond connection that is highly reliable and at the same time of reduced vertical extension. This allows for reducing the overall height of the electronic device. In the embodiments shown, the additional bond ball 4 is formed on the contact area which is elevated with respect to the second contact area. It has turned out that the end of the wire bond connection 3 that is arranged on the elevated contact area, i.e. the first contact area 21 in the exemplary embodiments, may be significantly strengthened by means of the additional bond ball 4, irrespective of whether the end of the wire bond connection is the first end 31 or the second end 32. However, the method is also suitable for making electrical connections between contact areas being arranged on an equal level.
Furthermore, a further additional bond ball may be arranged on the second contact area 22, so that both ends of the wire bond connection 3 are provided with an additional bond ball.
The invention is not restricted to the exemplary embodiments by the description on the basis of said exemplary
embodiments. Rather, the invention encompasses any new feature and also any combination of features which in particular comprises any combination of features in the patent claims and any combination of features in the
exemplary embodiments, even if this feature or this
combination itself is not explicitly specified in the patent claims or exemplary embodiments.

Claims

Claims
1. An electronic device (1) comprising a first contact area (21), a second contact area (22) and a wire bond connection (3) between the first contact area and the second contact area, wherein the wire bond connection extends between a first end (31) of the wire bond connection and a second end (31) of the wire bond connection and wherein an additional bond ball (4) is arranged on top of the wire bond connection.
2. The device as claimed in claim 1,
wherein a main plane (210) of extension of the first contact area is arranged in an elevated manner with respect to a main plane of extension (220) of the second contact area, so that the wire bond connection only extends on a side of the main plane of extension of the second contact area that faces the first contact area.
3. The device as claimed in claim 2,
wherein the first contact area is a bond pad of a
semiconductor chip (6).
4. The device as claimed in claim 2 or 3,
wherein the additional bond ball is arranged on top of the first contact area.
5. The device as claimed in any of the preceding claims, wherein the first end is a bond ball and the second end is a wedge bond.
6. The device as claimed in claim 5,
wherein the additional bond ball is formed on top of the wedge bond.
7. The device as claimed in claim 5,
wherein the additional bond ball is formed on top of the bond ball .
8. The device as claimed in claim 2 or 3,
wherein the first end is a bond ball, said bond ball being arranged on the first contact area, and wherein the
additional bond ball is arranged on top of the bond ball.
9. The device as claimed in claim 8,
wherein a maximum extension of the additional bond ball is smaller than a maximum extension of the bond ball.
10. The device as claimed in claim 2 or 3,
wherein the second end is a wedge bond, said wedge bond being arranged on the first contact area, and wherein the
additional bond ball is formed on the wedge bond.
11. The device as claimed in claim 10,
wherein an underlying bond ball (5) is arranged between the first contact area and the wedge bond.
12. The device as claimed in claim 11,
wherein a wedged part (34) of the wedge bond overlaps a center of the underlying bond ball in top view.
13. A method for forming an electrical connection comprising the steps:
a) providing a first contact area (21) and a second contact area (22 ) ,
b) forming a wire bond connection (3) between the first contact area and the second contact area, said wire bond connection extending between a first end (21) and a second end (22 ) ; and
c) forming an additional bond ball (4) on top of the wire bond connection.
14. The method as claimed in claim 13,
wherein the additional bond ball is thinned or removed subsequent to step c) .
15. The method as claimed in claim 13 or 14,
wherein a kink (36) is formed in the wire bond connection such that the kink overlaps the first contact area in top view and wherein the additional bond ball is formed on top of the kink.
PCT/EP2012/068854 2012-09-25 2012-09-25 Electronic device and method for forming an electrical connection Ceased WO2014048449A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2012/068854 WO2014048449A1 (en) 2012-09-25 2012-09-25 Electronic device and method for forming an electrical connection

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2012/068854 WO2014048449A1 (en) 2012-09-25 2012-09-25 Electronic device and method for forming an electrical connection

Publications (1)

Publication Number Publication Date
WO2014048449A1 true WO2014048449A1 (en) 2014-04-03

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220278060A1 (en) * 2020-12-07 2022-09-01 Infineon Technologies Ag Molded semiconductor package with high voltage isolation

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020079354A1 (en) * 2000-12-22 2002-06-27 Chun-Chi Lee Wire bonding process and wire bond structure
US20050242159A1 (en) * 2004-04-28 2005-11-03 Texas Instruments Incorporated System and method for low loop wire bonding
US20080105459A1 (en) * 2006-11-02 2008-05-08 Rohm Co., Ltd. Electronic component and wire bonding method
US20110070729A1 (en) * 2009-09-01 2011-03-24 Oki Semiconductor Co., Ltd. Method of manufacturing semiconductor device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020079354A1 (en) * 2000-12-22 2002-06-27 Chun-Chi Lee Wire bonding process and wire bond structure
US20050242159A1 (en) * 2004-04-28 2005-11-03 Texas Instruments Incorporated System and method for low loop wire bonding
US20080105459A1 (en) * 2006-11-02 2008-05-08 Rohm Co., Ltd. Electronic component and wire bonding method
US20110070729A1 (en) * 2009-09-01 2011-03-24 Oki Semiconductor Co., Ltd. Method of manufacturing semiconductor device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220278060A1 (en) * 2020-12-07 2022-09-01 Infineon Technologies Ag Molded semiconductor package with high voltage isolation
US11817407B2 (en) * 2020-12-07 2023-11-14 Infineon Technologies Ag Molded semiconductor package with high voltage isolation

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