Decapsulation of silver-alloy wire-bonded devices

In order to reduce costs and improve the bonding process, silver has been recently introduced as an alternative to common bonding wire metals (gold, aluminum, copper), leading to new failure analysis issues. This study compares the efficiency of wet and dry chemistries for decapsulation on three Ag-based alloy wires. Introduction New developments of silver alloy bonding wire have emphasized specific problems due to silver alloy properties. Whereas this new type of wiring materials seemed to fulfill most challenges, like physical properties and reliability [1,2], it was suggested that epoxy molding compound (EMC) should be adapted in order to ease decapsulation[3]. Indeed, afterthe packaging industry moved from gold to copper wires, the failure analysis community had to come up with new decapsulation techniques [4,5]. Again, a new type of bonding will raise new problems of decapsulation. Furthermore, people facing failure analysis cases do not always have all required information on the type of EMC and the true composition of the bonding wires. Twomajor techniques of decapsulation regarding wirebonded devices are known: wet (acid) and dry etching (plasma). LASER ablation or milling are used for preopening, This study will compare the capabilities of these techniques on three different types of Ag-based wiring integrated circuits(IC).