Nitridation of Si by N 2 Electron Cyclotron Resonance Plasma and Integration with ScO x Deposition

Nitridation of silicon was achieved by exposure of silicon to N 2 electron cyclotron resonance plasma. The growth rate decreased as the nitridation time increased due to the growth process being limited by the diffusion of nitrogen through the growing SiN x layer. The thickness of the SiN x layer was about 1.5 nm for a nitridation time of 30 s, according to ellipsometry and transmission electron microscopy measurements. Additionally, scandium oxide (ScO x ) films were deposited by high pressure sputtering on top of the nitrided silicon, as well as in reference un-nitrided silicon, to study the influence of the nitridation process on the interface properties. The silicon nitride layer is efficient in preventing the growth of interfacial silicon oxide. The minimum of the density of interface traps (D it,min ) for ScO x /SiN x /Si structures with 30 s nitridation was around 2 × 10 11 cm -2 eV -1 , indicating an improvement with respect to the ScO x deposition on un-nitrided silicon with D it,min of about 1.2 × 10" cm -2 eV -1 . The best interface quality was obtained for the shortest nitridation time of 30 s. Finally, it was observed that the nitridation process greatly inhibits interface reaction during rapid thermal annealing at 1000°C.