Electrical properties of bulk silicon dioxide and SiO2/Si interface formed by tetraethylorthosilicate-ozone chemical vapor deposition

Abstract

Silicon oxide films have been deposited with chemical vapor deposition from TEOS/O-3 at low temperature below 400 degrees C for the gate insulator of thin-film transistors. The electrical properties of the bulk silicon oxide film and the SiO2/Si interface were investigated as a function of process parameters such as deposition temperature and TEOS/O-3 ratio using capacitance-voltage and current-voltage measurements. The breakdown strength increased and the leakage current decreased as the deposition temperature increased, but both were not significantly dependent on the TEOS/O-3 ratio. The breakdown strength of the film deposited at 380 degrees C was about 5 MV/cm. As the deposition temperature increased, the interface trap density (D-it) at Si midgap was almost constant, but D-it near E-v + 0.25 eV and E-v + 0.75 eV, which is the P-b center, decreased. The interface trap density was lowest when the TEOS/O-3 ratio was 0.35. It was confirmed that the deposition temperature influenced the electrical properties of the bulk oxide and the interface, but the TEOS/O-3 ratio affected only the interface properties. (C) 2000 The Electrochemical Society. S0013-4651(99)07-045-7. All rights reserved.