Etch Damage of Ge2Sb2Te5 for Different Halogen Gases

Abstract

Etch damage of Ge2Sb2Te5 (GST) has been investigated after etching in halogen inductively coupled plasmas (ICPs) such as CF4, Cl-2, and HBr. X-ray photoelectron spectra of Ge, Sb, and Te on the etched surfaces showed different depths of etch damage depending on the halogen-based plasmas. The blank GST etched by CF4 showed a lower total-halogen-percentage remaining on the etched surface than that etched by Cl-2 even though the depth of halogenations was the deepest for the GST etched by CF4 owing to the highest reactivity. However, when a GST feature masked by SiO2/Ti/TiN was etched, owing to the reaction of O from the SiO2 mask and C from CF4, a thinner/or no C-F polymer appeared to be formed on the etched sidewall; therefore, the highest halogenation was observed on the GST etched by CF4. Among the halogen-gases investigated, HBr showed the lowest damage due to the lowest reactivity. (C) 2011 The Japan Society of Applied Physics