Electromigration: a unique tool for microstructure engineering in metal films

Abstract

Electromigration has long been studied in the context of interconnect reliability in integrated circuits. It has also been used to create metal electrodes with nanogaps for molecular electronics. Here we report a new application of electromigration as a tool for locally engineering the microstructure of thin metal films. By controlling the level of disorder in the system, electromigration enables us to modify the electrical and electromechanical properties of the film. We have developed and implemented a feedback control algorithm for high precision control of the electromigration process. We have demonstrated the usefulness of the technique by using it to enhance the strain sensitivity of a metal based piezoresistive transducer. This enhancement can be attributed to the change in microstructure of the film which in turn changes the electronic transport mechanism.