Improvements on interface reliability and capacitance dispersion of fluorinated ALD-Al2 O3 gate dielectrics by C F4 plasma treatment

The characteristics of atomic layer deposited (ALD)- Al2 O3 gate dielectrics with C F4 plasma surface treatment have been studied in this paper. Fluorine atoms were observed to be incorporated at bulk Al2 O3 and pile-up at both Al Al2 O3 and Al2 O3 Si interfaces. X-ray photoelectron spectroscopy analysis demonstrated that Al-O bonds were replaced by Al-F and F-Al-O bonds as samples were treated in C F4 plasma. A physical model was proposed to explain the capacitance-equivalent-thickness (CET) degradation and capacitance- frequency-dispersion phenomenon. The C F4 plasma-treatment approach can immunize capacitance dispersion due to its excellent capability of interface trap passivation by fluorine atoms in Al2 O3 dielectrics. Fluorine incorporation was proven to improve the Al2 O3 dielectric characteristics of hysteresis, oxide reliability, and capacitance dispersion.