Evaluation of Different Cut Approaches on Advanced Beol Self-Aligned Double Patterning Scheme

Self-aligned double patterning (SADP) has been evaluated and employed as a back-end-of-line (BEOL) patterning solution for 10/7 -nm logic technology and beyond. In this paper, we study metal line end shapes created by both cut-first and cut-last approaches in a SADP BEOL flow, and investigate their impacts on capacitance and dielectric leakage. Very different line end shapes were obtained from the two approaches investigated, due to post 1 st patterning silicon surface oxidation differences. The cut-first approach results in a horn-shaped line end shape, while the cut-last approach yields a bowl-shaped line end shape. By using virtual fabrication on Coventor Inc.'s SEMulator3D®, a systemic investigation was performed to understand the impact of metal line end shapes on electrical performance. Our results indicate that capacitance and dielectric leakage performance of metal line to metal line and metal tip to metal tip, cut-first approach is reverse to cut-last approach. This study demonstrates that capacitance and dielectric leakage performance must be considered during selection of a BEOL SADP approach.