Wet-Etch Method for Patterning Metal Electrodes Directly on Amorphous Oxide Semiconductor Films

Abstract

Hydrogen peroxide (H2O2) was used as the etchant for patterning Mo source/drain (S/D) electrodes directly on the indium zinc oxide (IZO) semiconductor films. It was found that the edges of the Mo pattern were oxidized during etching, which was ascribed to the lateral penetration of the H2O2 etchant from the edges of the overlying photoresist. By adding alkali to the H2O2 etchant, the etch rate of Mo could be accelerated with an etch rate selectivity of Mo to IZO of as high as 4 × 104, and the edge-oxidization effect could be greatly reduced. Thin-film transistor (TFT) fabricated with this method exhibited an electron mobility of 11.5 cm2V−1s−1. The device also showed good electrical stability under positive or negative gate bias stress.