Low-Temperature One-Step Growth of AlON Thin Films with Homogenous Nitrogen-Doping Profile by Plasma-Enhanced Atomic Layer Deposition

The AlON film with homogeneous nitrogen-doping profile was grown by plasma-enhanced atomic layer deposition (PEALD) at low temperature. In this work, the precursors of the NH₃ and the O₂ were simultaneously introduced into the chamber during the PEALD growth at a relatively low temperature of 185 °C. It is found that the composition of the obtained film quickly changes from AlN to Al₂O₃ when a small amount of O₂ is added. Thus, the NH₃:O₂ ratio should be maintained at a relatively high level (>85%) for realizing the AlON growth. Benefited from the growth method, the nitrogen can be doped evenly in the entire film. Moreover, the AlON films exhibit a lower surface roughness than the AlN as well as the Al₂O₃ ones. The Al 2p and N 1s X-ray photoelectron spectra show that the AlON film is composed of Al-N, Al-O, and N-Al-O bonds. Moreover, a three-layer construction of the AlON film is proposed through the Si 2p spectra analysis and reconfirmed by the transmission electron microscopy characterization. At last, the electrical and optical tests indicate that the AlON films prepared in this work can be employed as the gate dielectric in transistor application as well as the antireflection layer in photovoltaic application.