Analysis of interface trap density of plasma post-nitrided Al2O3/SiGe MOS interface with high Ge content using high-temperature conductance method

The interface trap density (Dit) of SiGe metal-oxide-semiconductor (MOS) interfaces is analyzed by the conductance method to evaluate the effect of electron cyclotron resonance plasma post-nitridation on SiGe interfaces with various Ge compositions. We find that it is important to evaluate Dit of a high-Ge-content SiGe MOS interface by the conductance method to eliminate the effect of the large series resistance and capacitance due to the SiGe/Si hetero-interface. In conjunction with the high-temperature measurement in the conductance method, an equivalent circuit corresponding to the SiGe/Si hetero-interface enables us to eliminate the effect of the series resistance and capacitance of the hetero-interface. Thus, we successfully evaluated Dit at SiGe MOS interfaces with a Ge composition of up to 0.49 and the impact of plasma post-nitridation on the high-Ge-content SiGe interfaces. Although Dit increases with the Ge composition, plasma post-nitridation is effective even for a high-Ge-content SiGe interface. Dit of the Al2O3/Si0.51Ge0.49 interface was reduced from 7.8 × 1012 cm−2 eV−1 to 2.4 × 1012 cm−2 eV−1 by plasma post-nitridation. Thus, we reveal that plasma post-nitridation is useful to achieve superior Al2O3/SiGe MOS interfaces regardless of the Ge composition.