Very high resolution etching of magnetic nanostructures in organic gases

Two methods for high resolution dry etching of permalloy (NiFe) and iron (Fe) nanostructures are presented and discussed. The first involves the use of carbon monoxide (CO) and ammonia (NH3) as etching gases, the second uses methane (CH4), hydrogen (H2) and oxygen (O2). In both etching processes volatile metallo-organic compounds are the resulting reaction products. The patterned and dry etched thin films were observed with SEM and TEM to study the quality of each of the two processes. It is found that the CO/NH3 process yields higher etch rates, higher selectively with respect to the SiN mask used, and less redeposition than the CH4/H2/O2 process.