Wet-etching characteristics of Ge2Sb2Te5 thin films for phase-change memory

Etching of phase-change memory thin films is essential in the -processing for the manufacture of devices. The Ge2Sb2Te5 thin film as a typical material for such purposes can be control-etched by an aqueous solution of 20% nitric acids (HNO3). It was found that the Ge2Sb2Te5 films in amorphous state could be etched more uniformly than that in crystalline state. The etch rate can be well controlled to be 4.6 nm/s using such a solution, resulting in macroscopic and microscopic uniformity on amorphous films. It is therefore suggested that the crystallization annealing of Ge2Sb2Te5 thin films should be done after a wet etching process in the manufacture of phase-change random access memories.