Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF6 based plasmas

摘要

The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 C,plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) andinductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF6 and O2under different etch conditions. During RIE, the film exhibits good mask properties with etch ratesbelow 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in thesubnanometer region with lower platen power. The AlN film’s removal occurred through physicalmechanisms; consequently, rf power and chamber pressure were the most significant parameters inPEALD AlN film removal because the film was inert to the SFþx and Oþ chemistries. The etchexperiments showed the film to be a resilient masking material. This makes it an attractive candidate foruse as an etch mask in demanding SF6 based plasma etch applications, such as through-wafer etching,or when oxide films are not suitable.