Abstract: A method for creating deep features in a Si-containing substrate for use in fabricating MEMS type devices is provided. The method includes first forming a thin Ni hardmask on a surface of a Si-containing substrate. The Ni hardmask is patterned using conventional photolithography and wet etching so as to expose at least one portion of the underlying Si-containing substrate. The at least one exposed portion of the Si-containing substrate, not containing the patterned hardmask, is then etched in a plasma that includes free radicals generated from a gaseous mixture of chlorine (Cl2), sulfur hexafluoride (SF6) and oxygen (O2). The interaction of the gas species in the plasma yields a rapid silicon etch rate that is highly selective to the Ni hardmask. The etch rate ratio of Si to Ni using the inventive method is greater than 250:1.

Abstract: A method for creating deep features in a Si-containing substrate for use in fabricating MEMS type devices is provided. The method includes first forming a thin Ni hardmask on a surface of a Si-containing substrate. The Ni hardmask is patterned using conventional photolithography and wet etching so as to expose at least one portion of the underlying Si-containing substrate. The at least one exposed portion of the Si-containing substrate, not containing the patterned hardmask, is then etched in a plasma that includes free radicals generated from a gaseous mixture of chlorine (Cl2), sulfur hexafluoride (SF6) and oxygen (O2). The interaction of the gas species in the plasma yields a rapid silicon etch rate that is highly selective to the Ni hardmask. The etch rate ratio of Si to Ni using the inventive method is greater than 250:1.