Pulsed capacitively coupled plasmas for AIO etch process

Pulsed capacitively coupled plasmas (CCP) was applied to self-aligned-via (SAV) based all-in-one (AIO) etching process. Effects of bias and synchronous pulsed plasmas on the AIO etching process were analyzed to improve the reliability and reduce the RC delay in back-end-of-line (BEOL) copper interconnect system. For steps of hard-mask open and partial via etch, synchronous pulsed plasmas were applied. Etch front roughness could be reduced using shorter duty cycle, which might be related to its more uniform deposition of polymer and higher power at the initial active-glow period. For steps of trench and liner removal etch, bias pulsed plasmas were applied. The chamfer profile of via could be improved, and larger bottom critical dimension (BCD) of via could be achieved with shorter duty cycle, which might be related to its higher selectivity between N-doped carbon (NDC, SiCN) and low-k (SiCOH).