Patterning of N:Ge2Sb2Te5 Films and the Characterization of Etch Induced Modification for Non-Volatile Phase Change Memory Applications

In this paper, a detailed study on the etching characteristics of nitrogen doped Ge₂Sb₂Te₅ (N:GST) thin films is performed to elucidate the relationship between pattern fidelity and material modification. Multiple methodologies ranging from physical sputtering to chemically driven reactive etching are shown to successfully pattern highly anisotropic features in N:GST films while the advantages and limitations of each are discussed. Subsequently, the presence of material modification during patterning has been identified using a combination of depth profiled X-ray photoelectron spectroscopy (XPS), transmission electron microscopy and electron energy loss spectroscopy (TEM-EELS). Results indicate the selective removal of antimony and nitrogen along with an increased amount of oxidized tellurium. Lastly, a novel method to selectively remove damaged N:GST material is presented.