Basic Wet-Etching Solutions for Ge2Sb2Te5Phase Change Material

We report on basic wet-etching solutions for Ge2Sb2Te5(GST) phase change material. A scanning electronic microscope was used to observe the surface morphology and measure the etching rate. On the basis of the etching results, it was found that the aqueous solutions of 10 vol % H2O2plus 25 wt % bases, such as KOH, NH3⋅H2O, and tetramethylammonium hydroxide, resulted in lower etching rates but a much smoother surface than that of common acid solutions. In addition, the etching process could be well controlled. Further X-ray photoelectron spectroscopy study of the etched samples showed that GST, etched by KOH, possessed higher oxidized states than that by HNO3, which revealed that the etching process was milder in basic solutions, while the dissolution of GST was more favored in acid environments due to the protonation effect.