Selective Etching of HfO2 by Using Inductively-Coupled Ar/C4F8 Plasmas and the Removal of Etch Residue on Si by Using an O2 Plasma Treatment

Abstract

HfO2 thin lms were etched using an Ar/C4F8 inductively-coupled plasma (ICP) for high etch selectivity of HfO2/Si and the uorocarbon remaining on the silicon surface after the HfO2 etching was removed by using an oxygen ICP and its e ect was investigated. The etching of HfO2 using Ar/C4F8 magnetically-enhanced ICP (MEICP) improved the etch selectivity of HfO2/Si by more than three times, possibly due to the di erences in the thicknesses of the uorocarbon polymer layers formed on the surfaces of HfO2 and Si. In addition, the oxygen ICP treatment after the HfO2 thin lm etching by using Ar/C4F8 ICP removed the polymer layer on the silicon surface e ectively, so for the HfO2-nMOSFET (n-type metal-oxied-semiconductoreld-e ect-transistors) devices, an improvement in drain current of more than 60 % could be observed after the O2 ICP treatment.