Characterization of reactive ion etching of polysilicon over gate oxide for failure mode analysis deprocessing

There is not much work reported for RIE of polysilicon for FMA and moreover, there are still many challenging issues for RIE of poly silicon including etch selectivity, surface roughness, poly residues and the optimization of the process parameters. In this work, we have studied the poly silicon etching characteristics for chlorine and fluorine based RIE systems. We investigated the dependence of poly etch rate and etch selectivity on the process parameters including O₂ flow, chamber pressure, ICP power and RIE power. The goal of this work was to characterize the effects of process parameters on etch rate, etch selectivity and surface roughness for the etching of poly silicon over gate oxide in FMA de-processing.