Aluminum nitride as a masking material for the plasma etching of silicon carbide structures

In this paper is detailed a technique for the plasma etching of silicon carbide (SiC) utilizing aluminum nitride (AlN) as a masking material. The fabrication technique enables the use of non-metallic etch masks to etch SiC which can aid in preventing micromasking defects on the etch surface and degradation in the health of plasma etch tools. This is the first report of this fabrication process. Through the experimental characterization of a high density inductively coupled plasma etch tool operated with SF₆/O₂ chemistries, an etch recipe that yields a SiC etch rate of 0.4 ¿m/min, a selectivity of 16:1 (SiC/AlN), and features with a sidewall angle of approximately 10° was developed. In addition, scanning electron microscopy images revealed that the etch recipe yields smooth etch surfaces that are free of micromasking defects. Further investigations of these preliminary results could lead to advancements in the manufacturability of SiC for the development of harsh environment sensing technology and high-power electronics.