Single die stitch bonding

An integrated circuit device comprising an integrated circuit die mounted on a leadframe having a plurality of inner leads. The integrated circuit die has a plurality of bond pads that are electrically connected to the inner leads of the leadframe, wherein at least two bond pads are connected to a one of the plurality of inner leads and/or at least two inner leads are connected to one or more bond pads with a single bond wire. A single bond wire is connected to a first bond pad or inner lead and subsequently wedge or stitch bonded to a second bond pad or inner lead, then it is connected to a third bond pad or inner lead. The single bond wire requires only one connection area at each of the bond pad(s) and inner lead(s). The bond pad(s) of the die and inner lead(s) of the leadframe are thereby electrically connected together by the single bond wire.

RELATED PATENT APPLICATION

This application is related to commonly owned U.S. patent application Ser. No. 09/832,287, entitled “Arrangement and Method of Arrangement of Stacked Dice in an Integrated Electronic Device” by Joseph Fernandez, filed Apr. 10, 2001, and is hereby incorporated by reference herein for all purposes.

FIELD OF THE INVENTION

The present invention is related to connecting to integrated circuit bond pads, and more particularly to connecting related bond pads by stitch bonding a continuous bond wire thereto.

BACKGROUND OF THE INVENTION TECHNOLOGY

An Integrated circuit device may comprise an semiconductor integrated circuit die mounted on a leadframe. The semiconductor integrated circuit die comprises a plurality of bond pads that are electrically connected to inner leads of the leadframe, e.g., using bond wires. The semiconductor integrated circuit die, the inner portion of the leadframe (inner leads) and the bond wires may be encapsulated into an integrated circuit package. After encapsulation, a border or frame on the outer portion of the leadframe is cut to separate outer leads of the leadframe into connecting pins or surface mount contacts which are used to electrically connect the electronic circuitry in the semiconductor integrated circuit die with other externally arranged electronic components mounted on a substrate or printed circuit board.

Integrated circuit devices are becoming more and more sophisticated while integrated circuit package size and the number of available package connections are being reduced. Limiting the number of package connections available for connecting to device circuits is necessary for both size and cost constraints. However, this may create a problem for the integrated circuit device manufacturer who must offer integrated circuit devices for many different types of configurations and applications. Integrated circuit device cost is reduced when a large quantity of the same device is produced. It is relatively easy to fabricate an integrated circuit device capable of many different configurations and uses than to have to perform various different metal mask operations so as to fabricate differently configured integrated circuit devices. A specific device configuration may then be selected during fabrication of the integrated circuit device with the leadframe by appropriate jumper connections between the die bond pads and inner lead fingers of the leadframe. Typically, various combinations of die bond pads are connected together through common connections to an inner lead(s) of the leadframe. However selecting a specific configuration in this fashion for configuration of the integrated circuit device becomes problematic when the reduced die, package and leadframe areas available for interconnecting option selection pads of the integrated circuit die are reduced. Making more than one wire bond connection to a die bond pad and/or inner lead of a leadframe may not be practical or even possible in the smaller and more densely packaged integrated circuits.

Therefore, there is a need for connecting a plurality of integrated circuit bond pads and/or inner leads of a leadframe together without requiring multiple connections thereto.

SUMMARY OF THE INVENTION

The present invention overcomes the above-identified problems as well as other shortcomings and deficiencies of existing technologies by providing multiple common connections in an integrated device while requiring only a single connection point at each of the commonly connected integrated circuit die bond pads and/or inner leads of a leadframe. A single wire is stitch or wedge bonded between one or more die bond pads and one or more inner leads of a leadframe to create a common connection therebetween.

According to an exemplary embodiment of the invention, an integrated device comprising an integrated circuit die having bond pads and a leadframe having a plurality of inner leads may have multiple common connections between one or more of the die bond pads and one or more of the inner leads of the leadframe. A single bond wire is wedge or stitch bonded to each of the one or more die bond pads and one or more inner leads of a leadframe that are desired to be commonly connected while requiring only a single attachment point at each of these one or more die bond pads and these one or more inner leads.

A technical advantage of the present invention is using a single wire stitch bond to create a common interconnection between one or more die bond pads and/or one or more inner leads of a leadframe. Another technical advantage is requiring only a single stitch bond wire to set device configuration. Still another technical advantage is a needing only a single point of connection to a die bond pad and/or inner lead of a leadframe for multiple common interconnections of one or more die bond pads and/or one or more inner leads of a leadframe. Yet another technical advantage is reducing the number of different metal mask configurations required for selecting device operating modes.

A feature of the present invention is the ability to add options to the integrated circuit package after wafer fabrication. Another feature is setting device mode options after wafer fabrication. Yet another feature is using only one connection point at each bond pad and inner lead of a leadframe.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The present invention provides multiple common connections in an integrated device while requiring only a single connection point at each of the commonly connected integrated circuit die bond pads and/or inner leads of a leadframe. A multiple common connection is provided by using a single bond wire which is stitch or wedge bonded to a single point at each die bond pad and inner lead of the leadframe that are commonly connected together.

Referring now to the drawings, the details of exemplary embodiments of the present invention are schematically illustrated. Like elements in the drawings will be represented by like numbers, and similar elements will be represented by like numbers with a different lower case letter suffix.

The term “wirebonding” is generally accepted to mean the interconnection (via wire) of components, contact pads and conducting tracks. There are two basic wirebonding techniques that may be used in thermocompression (T/C), thermosonic (T/S) or ultrasonic (U/S) bonding processes, they are ball bonding and wedge bonding. Referring toFIG. 1, in ball bonding a wire, e.g., bond wire110, is passed through a hollow capillary tool (not shown) and a small portion of the end of this wire is heated to a molten condition wherein the surface tension of the molten metal forms a spherical shape, or ball, as the bond wire material solidifies. The ball at the end of the wire is pressed onto a bond pad104of the semiconductor die102with sufficient force to cause plastic deformation and atomic interdiffusion of the ball and the underlying metallization of the bond pad104. This creates a low resistance connection between the bond pad104and the ball at the end of the wire.

The capillary tool containing the wire is then raised and repositioned over the next connection point, e.g., inner lead106of the leadframe. A precisely shaped wire connection called a wire loop is thus created. Deforming the wire against the inner lead106makes the second bond (e.g., wedge bond or stitch bond). The deformation of the wire against the inner lead106may have a crescent or fishtail shape made by the imprint of the capillary tool's outer geometry. After this second connection is made, the wire is clamped and then broken off after the bond connection.

Wedge bonding derives its name from the shape of the bonding capillary tool. In wedge bonding, the wire is fed at an angle from about 30–60 degrees from the horizontal bonding surface through a hole in the back of a bonding wedge of the capillary tool. Normally, forward bonding is preferred, i.e., the first bond is made to the die bond pad104and the second bond is made to the inner lead106of the leadframe. After the first bond operation, the wedge bonding capillary tool rises and executes a motion to create a desired wire loop shape (bond wire). At the second bond location, the wedge bonding capillary tool descends and makes the second bond connection. The movement of the axis of the wedge bonding capillary tool allows the wire to freely feed through the hole in the wedge bonding capillary tool. The bonded wire may be separated from the wire remaining in the wedge bonding capillary tool by using clamps to break the wire while machine bonding force is maintained on the second bond (clamp tear), or the clamp remains stationary and the wedge bonding capillary tool raises off the second bond area to tear the wire apart (table tear).

The wire is made of a conductive material such as metal, e.g., gold, copper, aluminum, combinations of these metals (alloys), or alloys of these metals in combination with other metals, e.g., Silicon (Si) and/or magnesium (Mg). The bonding surfaces may be coated or plated with a compatible conductive material, e.g., gold, aluminum, gold, or nickel, etc. It is contemplated and within the scope of the present invention that any type of conductive material, e.g., metal or metal alloy is within the scope of the present invention.

FIG. 1depicts is a plan view of a prior art integrated circuit die having bond pads thereon connected with bond wires to respective ones of inner leads of a leadframe. The integrated circuit die is represented by the numeral102and has a plurality of bond pads104thereon. The bond pads104are connected to the electronic circuits (not shown) comprising the die102. A leadframe (not entirely shown, but well known to those skilled in the art of integrated circuits) comprises a plurality of inner leads106, a plurality of outer leads108and a support structure or “die paddle” (not shown). The die102is initially supported by the leadframe die paddle. The outer leads108may be formed into connecting pins or surface mount contacts as desired. Bond wires110electrically connect the bond pads104to respective ones of the inner leads106. The die102and supporting die paddle, bond pads104, inner leads106and bond wires110may be encapsulated in an integrated circuit package, schematically depicted by the outline referenced by the numeral112.

Referring toFIG. 2, depicted is a plan view of a prior art integrated circuit die having two bond pads thereon connected with two bond wires to a common inner lead of a leadframe. Two bond wires110aand110bare attached to the inner lead106aand thereby electrically interconnect bond pad104a, bond pad104band the inner lead106atogether. A problem exists however in that the inner lead106amust have sufficient free bonding area to accommodate two bond wire connections. When more than two interconnections are required, this bonding area problem is further exasperated. As semiconductor integrated circuit devices become smaller and more complex, there may not be sufficient bonding area on an inner lead or bond pad to accommodate more than one bond wire connection.

Referring toFIG. 3, depicted is a plan view of a prior art integrated circuit die having two bond pads thereon connected with an internal metal mask jumper. During fabrication of the semiconductor integrated circuit die102a, a conductive jumper310may be created during a metallization step in the die fabrication process so as to interconnect, for example, bond pads104aand104b. The jumper310may be used to configure or set options within the die102a, however, different metallization masks and batch runs must be performed during the integrated circuit die fabrication process to achieve these different integrated circuit options. Thus, a using mask jumper(s)310is not cost effective for a small quantity of semiconductor devices. In addition, a greater parts inventory is required when using mask jumpers since larger quantities of each semiconductor die configuration must be fabricated in order to be cost effective.

Referring now toFIG. 4, depicted is a plan view of an integrated circuit die having two bond pads and an inner lead of a leadframe connected together with a single stitch bond connected bond wire, and two other inner leads of the leadframe connected to another bond pad with another single stitch bond connected bond wire, according to exemplary embodiments of the present invention. A single bond wire410aconnects bond pad104a, inner lead106aand inner lead106btogether and requires only one bond point a each connection area of the bond pad104a, inner lead106aand inner lead106b. A ball or wedge bond connection may be used at the first connection point of the bond wire410a, and subsequent connection points may use wedge (stitch) bonding. The bond wire410aremains unbroken (continuous) until the last connection has been made. The first connection of the bond wire410amay begin at either bond pad104aor inner lead106b. Preferably, the first connection will be at the bond pad104a. The intermediate connection at the inner lead106awill be a wedge (stitch) bond wherein the bond wire410aremains unbroken. For example, a simple interconnection operation may be performed as follows. First, the capillary tool bonds the bond wire410ato the bond pad104aof the die102, then the capillary tool moves to the inner lead106a. A wedge (stitch) bond is made to the inner lead106a, and then the capillary tool moves to the inner lead106band bonds the bond wire410athereto. In a similar fashion, bond wire410bmay interconnect bond pad104b, bond pad104cand inner lead106ctogether.

Referring now toFIG. 5, depicted is a plan view of the integrated circuit die illustrated inFIG. 4with the addition of a device mode selection jumper commonly connecting mode option selection bond pads on the die, according to another exemplary embodiment of the present invention. Bond pads404a,404band404care exemplary and may be greater or fewer in number depending upon the application and number of operational modes that may be selected for the semiconductor integrated circuit die102b. A stitch bonded jumper bond wire510may connect bond pads404a,404band404ctogether. When a different option or die configuration is desired, the bond pads404a,404band404cmay be interconnected or left unconnected as required.

FIG. 6is an elevational view of a single stitch bond connected bond wire, according to the exemplary embodiments of the present invention. The first connection of the bond wire410bmay begin at either bond pad104aor inner lead106. Preferably, the first connection will be at the bond pad104a. A connection to bond pad104bis made by stitch bonding the bond wire410bwhich remains unbroken or continuous until bonded to the inner lead106. After the bond wire410bhas been bonded to the inner lead106, it is separated from the wire at the tip of the capillary tool, thus completing the stitch bond.

The invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While the invention has been depicted, described, and is defined by reference to exemplary embodiments of the invention, such references do not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alternation, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts and having the benefit of this disclosure. The depicted and described embodiments of the invention are exemplary only, and are not exhaustive of the scope of the invention Consequently, the invention is intended to be limited only by the spirit and scope of the appended claims, giving fill cognizance to equivalents in all respects.