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Wire Bonding to Copper Bond Pads Without Using an Intervening Metallic Layer

IP.com Disclosure Number: IPCOM000100635D
Publication Date: 2005-Mar-16
Document File: 3 page(s) / 39K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for wire bonding gold wires directly to copper bond pads without using an intervening layer of non-corrosive metal. Benefits include reducing fabrication steps and process costs.

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Wire Bonding to Copper Bond Pads Without Using an Intervening Metallic Layer

Disclosed is a method for wire bonding gold wires directly to copper bond pads without using an intervening layer of non-corrosive metal. Benefits include reducing fabrication steps and process costs.

Background

Currently, an intervening conductive non-corrosive metal layer is used as a cap for copper bond pads for wire bonding. Electrical connections are formed along the exterior of an integrated circuit die to permit access to the logic circuitry contained within the die. Wire bonds, typically formed from gold wire, are used to connect the last layer of metal on the integrated circuit die to the exterior environment. Typically, the last layer of metal within a high-performance integrated circuit is copper. However, copper is not a self-passivating metal, and easily corrodes when exposed to ambient. The copper bond pads need to be protected from the ambient for wire bonding.

Copper bond pads require protective caps (or other permanent conductive materials) over them to prevent corrosion of the exposed copper. These caps are typically made of a less corrosion-susceptible or self-passivating material, such as tungsten, titanium, tantalum, or aluminum. Aluminum is one of the more common cap materials used. However, using protective caps is undesirable because they introduce additional materials, processing steps, and manufacturing complexity which can decrease die yields and increases costs.

General Description

The disclosed method wire bonds gold wires directly to copper without using an intervening layer of non-corrosive metal; this eliminates the corrosion of exposed copper bonds on the die. During the wire bond process, a U...