Mechanism of chemical mechanical polishing of Ti0.4Sb2Te3 film using KMnO4 as oxidizer in an acidic slurry

In this paper, the CMP behavior of KMnO4 on TST film has been investigated. The material remove rate (MRR) of TST film increases from 80 nm/min to 234 nm/min when the concentration of KMnO4 changes from 50 ppm to 500 ppm (Fig.1). which is much faster than 60nm/min for the 0.1 wt% H2O2-based slurry. The surface morphology of TST film post-CMP was observed by atomic force microscope (AFM) (Fig. 2). From Fig. 2, it can be observed that the roughness of TST films post-CMP were all below 0.7nm. In addition, the chemical mechanism between KMnO4 and TST film surface has been studied by the Open Circuit Potential (OCP), and potentiodynamic measurements such as Ecorrand Icorr. Finally, the X-ray photoelectron spectroscopy was also applied to analyze the chemical reaction mechanismof KMnO4 and TST film surface.