Effect of nitrogen passivation on the interfacial property and band offset of HfLaO/SiGe

Abstract

The effect of NH3 plasma treatment on the interfacial and dielectric property between ultrathin HfLaO and strained Si0.65Ge0.35 substrate is investigated by high-resolution cross-sectional transmission electron micrographs (HR-TEM), Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), near edge x-ray absorption fine structure (NEXAFS), valence-band spectra and current density–voltage (J–V). TEM, AES and XPS results confirm that the interfacial layer with N–Hf, La–N and Si–N/Si–O–N bonds acts as a barrier layer against interdiffusions during annealing to some degree. In addition, the signals of N 1s core-level and N K-edge NEXAFS spectra are seen to disappear completely after post-deposition annealing (PDA) at 900°C due to the dissociation of unstable N chemical states during high-temperature annealing. The valence-band offsets ΔEV of HfLaO/SiGe interfaces with and without nitridation are determined to be 3.38 ± 0.01 eV and 3.20 ± 0.01 eV, respectively. While the corresponding conduction-band offsets ΔEC are found to be 1.10 ± 0.01 eV and 1.28 ± 0.05 eV, respectively. Moreover, the nitrided capacitor after PDA shows a low leakage current density (J) of ∼9.15 × 10−8 A cm−2 at a gate bias of Vg = −2.0 V.