Effect of surface temperature on GeSbTe damage formation during plasma processing

Abstract

Phase Change Memory (PCM) materials can be damaged during plasma exposure leading to changes in phase transition behavior. Etch-induced damage and crystallization properties of GeSbTe (GST) were evaluated as a function of substrate temperature, plasma chemistry, and plasma exposure time. Enhanced damage formation is related to selective elemental depletion and non-volatilized etch residue retention in the near surface region. These experiments validate literature findings that crystallization time increases with reduction in film thickness for GST samples capped with a thin SiO2 film, indicating the presence of a modified layer which serves as an interface layer material. A direct comparison of passivating properties of hydrofluorocarbon and hydrocarbon on GST can be more conclusive with a fine tuning of film thickness and an evaluation of total residue retention with depth profiling.