Effect of Halogen-Based Neutral Beam on the Etching of Ge2Sb2Te5

Abstract

In this work, the degradation of the GST surface after etching by a neutral beam was investigated and compared with that in the case of inductively coupled plasma etching, using Cl2 and HBr. The XPS (X-ray photoelectron spectroscopy) compositional depth profiling of the blank etched GST shows a shift of the peaks related to Ge, Sb and Te to a higher energy, indicating the degradation of GST in the case of both ICP etching and neutral beam etching. Cl2 showed more severe degradation compared to HBr for both etching systems due to the higher reactivity of Cl2 with GST than HBr. However, the neutral beam etched GST showed less surface halogenation and less change of the surface composition. In addition, when the compositional change on the etched sidewall of the patterned GST feature was investigated after etching using Cl2, the significant degradation of the GST sidewalls by halogenation was observed for the ICP etched GST while no significant degradation was observed for the neutral beam etched GST. The lower degradation of the neutral beam etched GST is believed to be due to the higher ratio of energetic vertical particle flux to random halogen radical flux to the GST compared to the ICP etching.