Plasma etching of high- k and metal gate materials

Abstract

Etching characteristics of high- k dielectric materials (HfO 2) and metal electrode materials (Pt, TaN) have been studied in high-density chlorine-containing plasmas at pressures around 10 mTorr. The etching of HfO 2 was performed in BCl 3 without rf biasing, giving an etch rate of about 5 nm/min with a high selectivity of >10 over Si and SiO 2. The etching of Pt and TaN was performed in Ar/O 2 with high rf biasing and in Ar/Cl 2 with low rf biasing, respectively, giving a Pt etch rate of about several tens nm/min and a TaN etch rate of about 200 nm/min with a high selectivity of >8 over HfO 2 and SiO 2. The etched profiles were outwardly tapered for Pt, owing to the redeposition of etch or sputter products on feature sidewalls, while the TaN profiles were almost anisotropic, probably owing to the ion-enhanced etching that occurred.