Trimming of Silicon Nitride Hard Mask Using Cyclic Deposition and Etch Process

Silicon nitride (SiN) hard mask (HM) has been investigated to achieve sub-100nm of high aspect ratio (HAR) pattern. In this study, SiN HM trimming technique is developed by mean of cyclic reactive ion etching (RIE) for the vertical profile required in advanced DRAM memory fabrication. Furthermore, the SiN CD trim rate is revealed as ~ 2 nm per cycle.