Challenges of Ultra low-k integration in BEOL interconnect for 45nm and beyond

This paper presents some major integration challenges in Ultra low-k (ULK) Back-End-Of-Line (BEOL) interconnects for 45nm and beyond. The discussions mainly address the challenges that arise from ultra violet (UV) curing that cause changes in the composition of Nitrogen doped Silicon Carbide (SiCN), poor mechanical strength of ULK, Reactive Ion Etching (RIE) and barrier deposition plasma induced damage at the sidewall and the bottom of the trench, and gap-fill limitation of the copper (Cu) process. The physical characterization and Resistance-Capacitance (RC) results of the ULK integration are also presented.