Curing of polyimide and the effect of the TEOS SiO2 barrier layer on the electromigration of sputtered Cu with polyimide passivation

Abstract

The curing process of polyimide and the electromigration of copper films with polyimide (PI) passivation are studied. Thermal analysis of polyimide suggests that imidization completes at similar to200degreesC with an endothermic reaction associated with the breaking of the C-OH and N-H bonds as revealed by Fourier transformation infrared spectroscopy (FTIR). Although there is 89.8% weight loss when PI is heated from 20 degreesC to 200 degreesC, outgassing of PI passivation is still observed at higher temperatures. Carbon, nitrogen, and oxygen atoms diffuse into Cu during thermal processing of PI/Cu films. The tetraethyl orthosilicate (TEOS) SiO2 films are used as the barrier layer between PI and Cu to retard the poisoning of Cu. The effect of TEOS SiO2 film on electromigration of Cu is investigated.