Etch Mechanism of AlN Thin Film in Cl 2 /Ar Inductively Coupled Plasma

The etching characteristics of aluminum nitride (AlN) were investigated with the etch rate of AlN thin film and the selectivity of AlN to SiO 2 in an inductively coupled Cl 2 /Ar plasma. The AlN etch rate was linearly increased with increasing bias power. However, the AlN etch rate appeared a non-monotonic behavior with an increasing Cl 2 ratio in the Cl 2 /Ar plasma and pressure. Since the AlN thin films were of the relatively high melting point and binding energy, the high energetic positive ions were required to break Al-N bonds and to form volatile etch by-products, resulting in a high etch rate. The chemical condition on the surfaces of AlN thin films was investigated with X-ray photoelectron spectroscopy and the volatile etch by-products were observed. As a result, AlN etching mechanisms have been suggested to be an ion-enhanced chemical etching.