Investigation of stress-induced voiding inside and under VIAS in copper interconnects with “wing” pattern

Stress induce voiding (SIV) inside and under vias in copper interconnects with ldquowingrdquo-pattern were investigated for 90 nm and 65 nm node processes. The difference of two voidings are the resistance change during acceleration test and the diffusion path. However, common features were found between both types of voiding; the interconnect fails fast as the ldquowingrdquo area grows. Both types of voiding have a critical ldquowingrdquo area where failure never occurs. Both of voiding is more affected by diffusion source than by stress gradient.