Methods for performing plasma etching operations on microelectronic structures

A method for etching a layer of a microelectronic structure wherein said microelectronic structure comprises a layer of polysilicon to be etched on a layer of silicon oxide (SiO.sub.2), said method comprising steps of:

• masking said polysilicon layer to be etched so that portions of said polysilicon layer are exposed;
• supplying an etching gas;
• supplying an additional gas which generates a compound having a carbene structure when exposed to a plasma discharge;
• generating a plasma of said etching gas and said additional gas to thereby etch said exposed portions of said polysilicon layer and to form said compound having said carbene structure;
• supplying oxygen;
• and
• generating a plasma of said oxygen.

A method for etching a metal layer of a microelectronic structure, said method comprising steps of:

• masking said metal layer to be etched so that portions of said metal layer are exposed;
• supplying an etching gas;
• supplying an additional gas which generates a compound having a carbene structure when exposed to a plasma discharge;
• and
• generating a plasma of said etching gas and said additional gas to thereby etch said exposed portions of said metal layer and to form said compound having said carbene structure;
• wherein said etching gas includes chlorine.