Magnetically enhanced etching of sub-0.5 μm polysilicon gates

Abstract

We have compared Cl2 and HBr for etching polysilicon lines in a band magnetron cathode reactor. The experiments were designed utilizing response surface methodology. Our study shows a significantly wider operating window with the HBr chemistry. Typical results obtained are a polysilicon etch rate of 1500–2000 Å/min, selectivities 100:1 poly:SiO2 and 10:1 poly:photoresist. Direct-current bias values were under 100 V, and operating pressures were less than 6 mTorr. The results for 0.25 μm lines indicate that etching was free of undercut, oxide trenching, and polysilicon notching over steps. No evidence of polymer formation was observed using scanning electron microscopy and optical emission spectroscopy.