Effect of nitrogen doping on the performance of Ge₂Sb ₂Te₅ films in chemical mechanical polishing

The effects of nitrogen doping on Ge₂Sb₂Te ₅ (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 20 sccm at 300 °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 (I-V) 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.