Reactive and anisotropic etching of magnetic tunnel junction films using pulse-time-modulated plasma

Reactive and anisotropic etching of magnetic tunnel junction (MTJ) stacked films has been achieved using pulse-time-modulated (TM) plasma. While corrosion and delamination of MTJs are observed in continuous wave discharge plasma, a chlorine pulse-time-modulated plasma achieved a high MTJ etching rate without corrosion or delamination. The authors think that the negative ions enhance the chemical reactions on the surface of magnetic films. The magnetic characteristics are also significantly improved by using TM plasma because of reduced residues and improved tapered profiles. Accordingly, TM plasma etching is a promising candidate for high-rate and damage-free MTJ etching for magnetoresistive random access memory devices.