Effect of nitrogen doping on the performance of Ge2Sb2Te5 films in chemical mechanical polishing

Abstract

The effects of nitrogen doping on Ge2Sb2Te5 (GST) films for chemical mechanical polishing (CMP) and their performance were investigated. Nitrogen doping was controlled using a rapid thermal annealing system with nitrogen gas flow rates that varied from 0 (to) over right arrow 20 sccm at 300 degrees C. The material removal rate, surface characteristics and crystal structure of the nitrogen doped GST films after CMP were examined by X-ray diffraction (XRD), scanning electron microscopy, and atomic force microscopy. XRD patterns revealed that the intensities of crystalline diffraction peaks decreased with increasing nitrogen flow rate. With increasing flow rate, the material removal rate and surface roughness of GST films reduced owing to nitrogen doping effects. Current voltage (IV) characteristics of the nitrogen doped GST films after CMP showed changes in the threshold voltage owing to changes in crystallization and surface roughness. Further, Nitrogen doped GST films in CMP showed a strong correlation with material removal rate, surface roughness, and crystallization. (C) 2014 The Japan Society of Applied Physics