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 60 nm/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 0.7 nm. 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 mechanism of KMnO₄ and TST film surface.