WSi2/Poly-Si Gate Etching Using a TiON Hard Mask

Abstract

We found that the WSi2 etch selectivity over TiON was high enough in Cl2/O2 plasma to allow the use of TiON as an etching mask for WSi2/polysilicon gate etching. The high content of Ti–O bonds in TiON films is assumed to be the reason why TiON films can serve as etching masks. Anisotropic etching down to a line width of 0.06 µm was achieved using TiON thin films as etching masks. We can also avoid charging damage from the electron shading effect by using thin TiON films as etching masks. In a photolithographic context, we can expect to obtain improved critical dimension controllability by adopting an organic antireflecting coating (ARC)/TiON stacked layer as an antireflecting layer for WSi2/polysilicon gate definition.