Effect of O2 on etch characteristics of Co2MnSi thin films in CH4/O2/Ar gas mixture.

Co₂MnSi thin films masked with TiN films were etched in CH₄/Ar and CH₄/O₂/Ar plasmas by inductively coupled plasma reactive ion etching. The etch rates decreased with increasing CH₄ concentration in CH₄/Ar gas, whereas the etch selectivity increased. The addition of O₂ to CH₄/Ar gas resulted in significant improvement in the etch profile but a decrease in the etch rates. Optical emission spectroscopy showed that a variety of CO_x, OH, and H₂O species were formed in the CH₄/O₂/Ar plasma, acting a role as a passivation layer to protect the pattern sidewalls. X-ray photoelectron spectroscopy also confirmed the formation of metal oxides on the film surface, which could be sputtered off easily by Ar ion bombardment. A high degree of anisotropy of Co₂MnSi films was obtained in the CH₄/O₂/Ar etch gas. [ABSTRACT FROM AUTHOR]