Effect of surface temperature on GeSbTe damage formation during plasma processing

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.