Plasma Damage during Sputtering of Tantalum Oxide Thin Films on MOS Substrate by Selected Methods

Abstract

Tantalum oxide (Ta₂O₅) thin films were sputtered onto MOS structural diodes and MOS-FETs with Si wafer substrates by a number of methods, including RF reactive sputtering, RF reactive magnetron sputtering and ion beam sputtering, and the plasma-induced damage was evaluated by means of changes in flat-band potential in measurement of the capacitance-voltage (C-V) in the case of MOS diodes, and the change in transistor parameters in the case of MOS-FETs.
(1) The most severe plasma-induced MOS damage occurred under ordinary RF sputtering conditions. The use of ion beam sputtering reduced the plasma-induced MOS damage compared from that in reactive RF sputtering.
(2) The as-sputtered Ta₂O₅ films were all in amorphous structure with crystallization temperatures of about 730°C.