Dry Etching of Al2O3 Thin Films in O-2/BCl3/Ar Inductively Coupled Plasma

In this study, the etch properties of Al2O3 thin films deposited by atomic layer deposition were investigated as a function of the O-2 content in BCl3/Ar inductively coupled plasma. The experiments were performed by comparing the etch rates and selectivity of Al2O3 over the hard mask materials as functions of the input plasma parameters, such as the gas mixing ratio, DC-bias voltage, ratio-frequency (RF) power and process pressure. The highest obtained etch rate was 477 nm/min at an RF power of 700 W, O-2 to BCl3/Ar gas ratio of 15%, DC-bias voltage of -100 V and process pressure of 15 mTorr. The deposition occurred on the surfaces when the amount of O-2 added to the BCl3/Ar gas was too high at a low DC-bias voltage or high process pressure. X-ray photoelectron spectroscopy was used to investigate the chemical reactions on the etched surface.