The etching mechanism of (Bi4-xLax)Ti3O12 (BLT) thin films in Ar/Cl-2 inductively coupled-plasma (ICP) was investigated as a function of gas mixing ratios, process pressure, and ICP powers at fixed other conditions. Etch rates were measured by using an a-step surface profiler. The maximum etch rate of BLT thin films was 117 nm at 0.8 Ar/(Ar+Cl-2) gas mixing ratios with following conditions: process pressure of 15 mTorr, gas flow rate of 20 sccm, ICP power of 700 W, and dc bias of -150 V. The etch rate was increased as decreasing the process pressure. For a detailed investigation of etching mechanisms of BLT thin films, the ion energy distributions of each positive species were measured using quadrupole mass spectrometer and analyzed those data. Also the electron energy distribution was measured as a function of Ar/Cl-2 gas mixing ratios. (c) 2006 American Vacuum Society.