The improvement of atomic layer deposited SiO2/4H-SiC interfaces via a high temperature forming gas anneal
Arne Benjamin Renz, Oliver James Vavasour, Peter Michael Gammon, Fan Li, Tian Xiang Dai, Marina Antoniou, G.W.C. Baker, Erfan Bashar, Nicholas E. Grant, John D. Murphy, Philip Mawby, Vishal Ajit Shah
Abstract
This letter reports on the improvement of a SiO2 layer formed by atomic layer deposition on 4H-SiC, using a post-deposition anneal in forming gas ambient. Capacitance–voltage measurements revealed good electrical properties, compared to a thermal oxide which was grown in N2O, with flatband voltage values averaging at -0.29 V and a low positive mobile ion charge density in the order of 1010 cm−2. XPS analysis revealed the FG annealed sample to have the most Si rich interface comparatively to other PDAs, with a C:Si ratio of 0.72, allowing more Si bonds to be terminated. SIMS analysis identified an increase in hydrogen near the interface of the FG-annealed sample with a peak concentration of 2.12 × 1021 cm−3. It is concluded that the improvement in electrical performance is due to the hydrogen passivating trap states at the SiO2/4H-SiC interface.