Comparison of 40MHz and 60MHz HF Frequencies in Dual-Frequency CCP for Low-K AIO Process

Dual-frequency capacitively coupled plasma (CCP) etching is widely used for dielectric etching in back-end of line (BEOL) processes, such as all-in-one (AIO). In this setup, the higher frequency power primarily controls plasma density, while the lower frequency power influences ion bombardment. This study compares two common frequency combinations, 40/13MHz and 60/13MHz, analyzing etching profiles, depth, HM selectivity uniformity, and defect yield results in low-k dielectric AIO processes. Overall, with process optimization, both combinations achieve similar etching profiles. However, the 60/13MHz combination shows poorer uniformity and defect performance, which proves challenging to mitigate through hardware-based CIP adjustments.