Stress-induced voiding under vias connected to "narrow" copper lines

Abstract

Stress-induced voiding under vias connected to "narrow" Copper (Cu) lines (SIV-N) was observed, for the first time, using newly prepared test structures which consisted of isolated vias between narrow (0.14 mum-wide) and very long (200 mum-long) 2-level Cu wires. Mechanism of SIV-N is different from that of well-known stress-induced voiding under vias connected to "wide" Cu lines (SIV-W), because SIV-N cannot occur during actual time according to the model that explains SIV-W. In addition, we found the effect of plasma pretreatment of cap dielectrics and cap dielectrics themselves on SIV-N and the other reliability issues, and succeeded in obtaining the condition which satisfied SIV-N, SIV-W and EM