Chemically assisted sputter etching of permalloy using CO or CL2

Abstract

Redeposition-free patterns have been etched in 3000 Å thick permalloy films using the technique of chemically assisted sputter etching. This technique involves the simultaneous adsorption of a reactant gas from a molecular beam source and normally incident argon ion bombardment. Experimental conditions with Cl2 adsorption can be maintained to etch the permalloy at 80 Å/min and to etch positive photoresist at 110 Å/min. These etch rates are not significantly different from rates obtained with argon ion milling, even though the permalloy surface is known to incorporate Cl2. Redeposited material observed with Cl2 chemically assisted sputtering has been shown to be water soluble, and can be completely removed from feature sidewalls prior to stripping the resist. Linewidth measurements show that no feature broadening occurs on 2 μ line and space patterns, within the precision of the measurement (±0.2 μ). Chemically assisted sputter etching with the adsorption of CO resulted in reduced etch rates and increased redeposition. Both of these effects are attributed to the formation of carbides on the alloy surface during the process.