Novel electrochemical approach to study corrosion mechanism of Al–Au wire–bond pad interconnections

Abstract

A gold-aluminium material combination is typically employed as an interconnection for microelectronic devices. One of the reliability risks of such devices is that of corrosion of aluminium bond pads resulting from the galvanic coupling between an aluminium bond pad and a gold wire. The research presented in this manuscript focuses on studying bond pad corrosion by selecting an appropriate model system and a dedicated set of electrochemical and analytical experimental tools. Taking into account the complex three-dimensional structure and the small dimensions of Au-Al interconnections (around 50-100 mm), a dedicated and novel experimental approach was developed. Au-Al covered silicon chips were developed under clean room conditions. Three-dimensional electrodes were mimicked as flat, two-dimensional bond pad model systems, allowing the use of microelectrochemical local probe techniques. Thin gold films were applied on Ti-Al covered silicon surfaces, and their morphology and electrochemical behaviour were analysed using the localised electrochemical cell, scanning vibrating electrode technique, scanning electron microscopy-energy dispersive X-ray spectroscopy, scanning electron microscopy-focused ion beam and Auger electron spectroscopy. The results revealed that the electrochemical behaviour of thin gold films was influenced by the underlying metal layers and the microstructural changes during heat treatment. The effect of the underlying layers on the electrochemical properties of the top gold layer was attributed to a mixed potential behaviour and microgalvanic interactions, which was more pronounced after heat treatment. Overall, the current experimental approach can be employed to study the mechanism of electrochemical events that are occurring on metallic interconnections in different electronic devices.

Green Corrosion Inhibitor for Electronics

“…Furthermore, a galvanic couple is formed when electric contact is established between two dissimilar metals in the humid environment, which is termed as bimetallic corrosion or galvanic corrosion. An aluminum bond pads coupled to gold wire is common form of integrated circuit galvanic corrosion [15].…”

Influence of HCl Concentration on Corrosion Behavior between Au or Cu Bonding Wires and the Bond Pad for Semiconductor Packaging

“…In corrosive environments, galvanic corrosion occurs in bonding wires and Al bond pads bonded together due to the potential differences [8,13,17]. The bonding wire with a high potential has corrosion resistance, while the Al bond pad with a low potential corrodes, causing the formation of cracks [6,17,[30][31][32][33]. As these cracks propagate to the center of the bond, they accelerate the crack growth due to crevice corrosion, causing the separation of the wire and pad [8,13,26].…”

Exploring water and ion transport process at silicone/copper interfaces using in-situ electrochemical and Kelvin probe approaches

“…Upon diffusion through the polymer, the contaminants will reach the packaging/metallic circuitry interface and initiate an interfacial corrosion process. Reports devoted to the basic understanding of the transport phenomena involved are limited [3][4][5][6][7]. Two main transport pathways are identified in the microelectronics and LED packaging systems.…”