Potassium persulphate based silica slurry for germanium chemical mechanical planarization

Department of Chemical Engineering, Indian Institute of Technology, Guwahati-781 039, Assam, India
Department of Chemical Engineering, National Institute of Technology Raipur, Raipur-492 010, Chhattisgarh, India
E-mail: rmani.che@nitrr.ac.in
Manuscript received online 30 April 2020, accepted 01 June 2020

This study is based on germanium (Ge) chemical mechanical planarization (CMP) by potassium persulphate (KPS) as oxidizer in fumed silica slurry. All experiments were performed at room temperature to acquire Ge etch rate and removal rate. The effect of pH, tablespeed, downpressure and potassium persulphate concentration on germanium removal rate was studied. Higher etch rate and removal rate were obtained in alkaline pH attributable to higher oxidation of germanium surface followed by fast dissolution of germanium hydroxide complexes. The system followed non-Prestonian behavior. A probable reaction mechanism for germanium removal in potassium persulphate based silica slurry is proposed.