Printed Electronics

Nanometer sized particle based printing method on flexible substrates is one of the most promising candidates for a mass production using roll-to-roll process with a high patterning resolution and low temperature. This printing method has to overcome the reliability issues including interconnects failure under electrical current stressing conditions because the porous structure which contains abundant of vacant area and voids, is vulnerable to the microstructural changes under the electrical current stressing. This phenomenon generally is considered as the electromigration (EM) failure of interconnects, which is the atomic displacement due to momentum transfer from electron carriers to metal atoms. We are interested in a printing method to fabricate Ag interconnects and their electrical properties. Associated changes of microstructures are measured under current stressing to investigate their EM behavior and verify the underlying mechanisms. Ag interconnects formed necks between Ag particles and densified after annealing process subsequent to the deposition, and metal atoms migrated in the direction of the electron wind force under accelerated current stressing condition resulting in the contributed grain growth and resistance increase simultaneously. The reason of reliability failure is considered as induced joule heat at a neck of particles due to current crowding effect and EM phenomenon is extremely accelerated around a neck and Ag interconnects discontinued accompanied with abnormal grain growth in the end. Therefore, this implies that EM lifetime can be improved by controlling microstructure. We could provide the guideline for the highly-reliable metal interconnects manufactured by printing methods in flexible electronics.