Characterization of ITO etching by spontaneously evaporated fume of hydrogen chloride

A simple etching process for indium tin oxide (ITO) film was investigated with atmospheric fume of hydrochloric acid (HCl), which was spontaneously evaporated from HCl solution. The fume etching provided many advantages including simpler process, less extents of undercut, and smaller defects on ITO surface than wet etching. A high etching rate of 50–70 nm/min for ITO film on thermal oxide, glass, and flexible polyethyleneterephthalate substrate was obtained. Surface analyses including X-ray photoelectron spectroscopy and Fourier transform infrared (FTIR) spectroscopy suggested that the spontaneously evaporated HCl molecules chemically reacted with ITO and formed water dissolvable etch products. Since the chemical reaction was postulated as a sole source for the etching mechanism, the fume etching would be a suitable process for next-generation flexible electronic applications without any physical damages on substrate.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Fume of hydrogen chloride (HCl) was introduced for a simple ITO etching process. ► HCl fume was spontaneously formed and its ITO etching resulted in less isotropic etching performance than wet etching. ► SEM and XPS analyses provided that mechanism of fume etching was solely chemical reaction-driven.