Direct evidence of reactive ion etching induced damages in Ge2Sb2Te5 based on different halogen plasmas

The work we did was used to investigate the reactive ion etching (RIE) induced damages in Ge2Sb2Te5 (GST) based on different halogen plasmas (CF4, Cl2 and HBr). The figure showed here revealed the cross-sectional TEM images of the patterned GST samples: (a) Cl2-based plasma, (b) CF4-based plasma, (c) HBr-based plasma. The (b) and (c) show the cross section of TEM images for GST lines etched by CF4 and HBr gases. The etching sidewalls are both vertical and smooth with CF4 and HBr gases. However, it can be founded that an obvious damaged layer was observed near the boundary of sidewall in CF4 etched sample, which can be attributed to the high reactivity of F and its penetrability.