Plasma etch method for forming patterned chlorine containing plasma etchable silicon containing layer with enhanced sidewall profile uniformity

摘要

A method for forming a patterned silicon containing layer. There is first provided a substrate. There is then formed over the substrate a blanket silicon containing layer. There is then formed over the blanket silicon containing layer a patterned photoresist layer. There is then etched, while employing a first plasma etch method in conjunction with the patterned photoresist layer as a first etch mask layer, the blanket silicon containing layer to form a partially etched blanket silicon containing layer. The first plasma etch method employs a first etchant gas composition comprising an etchant gas which upon plasma activation forms an active fluorine containing etchant species. There is then etched, while employing a second plasma etch method in conjunction with the patterned photoresist layer as a second etch mask layer the partially etched blanket silicon containing layer to form a fully patterned silicon containing layer. The second plasma etch method employs a second etchant gas composition which upon plasma activation forms an active halogen containing etchant species other than an active fluorine containing etchant species. The present invention also contemplates an embodiment which incorporates a blanket hard mask layer formed interposed between the blanket silicon containing layer and the patterned photoresist layer. The present invention may be employed for forming gate electrodes within field effect transistors (FETs).