Characteristics of Thin Hf-Silicate Gate Dielectrics after Remote N-2 and N2O Plasma Post-Treatments

Abstract

We investigated the thermal stability and physical properties of nitrided Hf-silicate after applying N-2 and N2O plasma treatments. The Hf-silicate film was created by remote-plasma atomic layer deposition using Hf[N(CH3)C2H5](4) and Si[N(CH3)](3)H as source gases and O-2 plasma as the oxidant. After rapid thermal annealing in N-2 ambient, the Hf silicate crystallized at 800 degrees C, while Hf-silicate films after the N-2 and N2O plasma treatments remained amorphous after annealing at 800 degrees C. Remote-plasma treatment of Hf-silicate resulted in a shift of the O 1s peaks to a lower binding energy. The increase in peak intensities of the Si-O-N, Si-O-Hf, and Si-O bonds at the interface after annealing was higher after N2O plasma treatment than after N-2 plasma treatment. The accumulation capacitances of an as-grown Hf-silicate metal-oxide-semiconductor structure after N-2 plasma treatment show that it has a better capacitance density (280 pF) than the same structure after N2O plasma treatment (235 pF). The equivalent oxide thickness values for the Hf-silicate films after N-2 and N2O plasma treatments are 3.36 and 3.8 nm, respectively.