Ion beam assisted organic chemical vapor etch of magnetic thin films

An ion beam-assisted organic vapor etch process is demonstrated for patterning magnetic metal elements for potential applications in magnetoresistive random access memory devices. A thermodynamic analysis was performed to evaluate the feasibility of a chemical etch process, leading to the selection of acetylacetone (acac) and hexafluoroacetylacetone (hfac) chemistries. First, etching of cobalt and iron in acac and hfac solutions was studied, and it was determined that acac etches Co preferentially over Fe with a Co: Fe selectivity of similar to 4, while hfac etches Fe preferentially over Co with an Fe: Co selectivity of similar to 40. This motivates the use of acac and hfac to etch Co and Fe, respectively, but the etch rate was, in the gas phase, too small to be considered a viable process. An argon ion beam was employed in between organic vapor exposures and resulted in significant enhancement in the etch rates, suggesting an ion-enhanced chemical etching process is viable for the patterning of these magnetic metal elements. (C) 2017 American Vacuum Society.