The Investigation on Partial Via ETCH of Low-K in MHM AIO Process

Considering better performance of low-k damage, Metal Hard-Mask (MHM) All-In-One (AIO) process is proposed and widely used from sub-65nm CMOS technology node. Via performance post partial via (PV) etch plays a significant role in final yield and reliability test. In this work, via etch performance is investigated from four points of via bottom roughness, via profile and pattern ER, via depth loading and TiN selectivity. Meanwhile, the effects of typical gases used in partial via etch and how they affect those key indexes are analyzed. Both etch mechanism and effective tuning knobs in via etching of low-k are provided in this study. Moreover, CH3F/N2 base shows the best overall performance in our study, deserving to be further investigated for development of advanced technology node.