Etch Properties of TiN Thin Film in Metal–Insulator–Metal Capacitor Using Inductively Coupled Plasma

In this work, we investigated the etching characteristics of the titanium nitride (TiN) thin film in BCl 3 /Cl 2 plasma and the effect of the gases (O 2 and Ar) added to BCl 3 /Cl 2 plasma. The etch rate was measured under various etching conditions, such as the gas mixing ratio, the process pressure and the substrate temperature. The maximum etch rate of TiN thin film was 343 nm/min in BCl 3 (25%)/Cl 2 (75%) plasma. To enhance the etching characteristics, we added O 2 and Ar gas to BCl 3 (25%)/Cl 2 (75%) plasma. Added O 2 and Ar gas flow rates were 2, 5, 8, and 10 sccm. The etch rates with O 2 addition decrease from 221 to 4 nm/min. The etch rate in Ar/BCl 3 /Cl 2 plasma decreased slightly compared with that in the case of O 2 addition. The nonvolatile etched byproduct was formed on the surface, and was analyzed by X-ray photoelectron spectroscopy (XPS) analysis. O 2 addition without Ar ion bombardment in BCl 3 /Cl 2 plasma leaded to increased morphological surface roughening. The etch rate decreased with increasing O 2 content owing to the O 2 reaction with Ti and TiO 2 layer formation on the surface. A nonvolatile etched byproduct was observed by XPS analysis. It could be estimated to be a Ti–Cl compound.