Reactive ion etching of indium tin oxide by SiCl₄-based plasmas - Substrate temperature effect

Abstract

In this paper, plasma etching of ITO over a large temperature range, i.e., 25°C to 250°C, based on the SiCl4 gas has been studied. CF4 and CH4 have been added into the plasma to examine the gas mixture effect. The result shows that, for each gas stream, there is a threshold temperature in the etch rate vs. temperature curve. Temperature has a drastic effect on the etch rate above the threshold temperature. This is because that the high substrate temperature enhances the etch reaction rate as well as the residue removal rate. Below the threshold temperature, the etch rate is slightly influenced by the temperature. This is probably due to the low residue removal rate. Even when the substrate temperature is higher than the threshold temperature, there exists a threshold power for each gas stream. This demonstrates that ion bombardment effect is not negligible at high temperature. Residue components on the etched surfaces have been identified with electron spectroscope for chemical analysis (ESCA). The residue formation mechanism can be used to explain the etch rate difference among various feed streams. © 1998 Elsevier Science Ltd. All rights reserved.