High-rate etching of single oriented AlN films by chlorine-based inductive coupled plasma for vibrational energy harvesters

This paper presents our development of a high-rate etching process for fully (0002)-oriented AlN films by using a chlorine-based inductively coupled plasma (ICP) and Ni thin films as hard masks. The influences of etching characteristics (etching rate, selectivity) on various parameters (etching power, pressure and gases mixture) were systematically investigated. We achieved etching rate of 723 nm/min, the highest value that has been developed for single-oriented AlN. Etching selectivity was optimized and reached ∼ 11, in this report. X-ray photoelectron spectroscopy measurements (XPS) offered a deep understanding of the etching processes and revealed the etching mechanism of AlN by chlorine for the first time.