The Use of Secondary Ion Mass Spectrometry to Investigate Wire Bonding Yield Problems on Gold Contacts

Abstract

With ongoing demand for high density wiring and high I/O on VLSI chips, the requirement of high wire bond yield is a challenge to achieve low cost, high performance and reliable products. Secondary Ion Mass Spectrometry (SIMS) was used to investigate the metallurgical contaminants on the gold wire bond pads and their impact on wire bond yields. SIMS depth profile studies showed that copper and nickel in concentrations greater than 1 wt% caused poor wire bondability, while copper concentration at less than 0.1 wt% resulted in good bondability of Al ultrasonic wire bonded to the gold pads.

Proposed ToF‐SIMS/XPS standardization methods for bonding wires in electronic packaging applications

“…Most work has concentrated on bond pad contamination where it has been shown that it results in reduced bond strength and bondability. [1] Surface characterization of the bond pads is relatively straightforward due to their simple geometry. Less studied is contamination on the wire itself.…”