Impact of Forming Gas Annealing and Firing on the Al2O3/p-Si Interface State Spectrum

The interface-state spectrum at the Al 2 O 3 /p-Si interface is investigated by Deep-Level Transient Spectroscopy on Metal-Oxide-Semiconductor (MOS) capacitors. It is shown that a Forming Gas Anneal or firing step leads to a significant reduction of the density of interface states (D it ). At the same time, it is found that the peak activation energy of the D it distribution lowers towards the valence band of Si. From a comparison with the DLTS data on 5 nm SiO 2 MOS capacitors, it is concluded that the same type of states is observed for both dielectrics, implying that the interface properties are determined by the thin interfacial SiO 2 layer.