THE REACTIVE ION ETCHING OF TRANSPARENT ELECTRODES FOR FLAT-PANEL DISPLAYS USING AR CL-2 PLASMAS/

Large area flat panel displays require high resolution patterning of t ransparent and high conductivity metal oxides, but the reliability of standard chemical etch techniques at high resolution is inadequate. Ti n oxide (SnO2) is a viable alternative to standard In2O3:Sn (ITO) over large areas but has been ignored due to the lack of a suitable etch p rocess. We have developed an Ar/Cl-2 reactive ion etch process capable of etching 4 mu m feature sizes and resolutions of 300 lines per inch with rates of up to 90 nm min(-1). Emission spectroscopy showed that atomic chlorine is a strong candidate for the active species and that volatile tin chlorides were generated as etch products. Furthermore, t he presence of impurity species, particularly hydrogen, was found to b e beneficial to the etch rate. Near etch completion, a dramatic decrea se in atomic tin emission was observed along with an increase in Cl em ission intensity. The etch rate for tin oxide using Ar/Cl-2 was higher than those obtained for ITO using alcohol-based plasmas without the p olymer deposition normally associated with organic gas plasmas. Thus t he use Ar/Cl-2 etching of SnO2 can provide high resolution transparent conductive electrodes that are uniform over a large area.