Development of electron cyclotron resonance and inductively coupled plasma high density plasma etching for patterning of NiFe and NiFeCo

Two different kinds of high density plasma reactors are found to be effective for dry etching of Ni0.8Fe0.2 and Ni0.8Fe0.13Co0.07. Using a Cl2/Ar plasma chemistry, electron cyclotron resonance and inductively coupled plasma system produce a factor of 2 higher etch rates than for pure Ar sputtering under the same conditions. The etch rates are a strong function of ion flux, ion energy, and plasma gas composition, all of which may be interpreted in terms of balancing formation of chloride etch products with efficient ion-assisted desorption of these products. Typical peak etch selectivities of ∼5 and ∼4, respectively, were obtained for NiFe over SiO2 and SiNx masks. Post-etch corrosion was also studied, and found to be strongly dependent on the conditioning of the reactor walls.