A novel method for the deposition of Si-SiO2 superlattices

A novel procedure is proposed for the deposition of Si/SiO2 multilayers by magnetron sputtering of an SiO2 target under a hydrogen-rich plasma. The ef fect of increasing hydrogen pressure (PH) was investigated For the case of a monolayer. This involved an increased enrichment in the Si of the deposit ed film, because of the incorporation deficit of oxygen that is efficiently "reduced" by hydrogen. This was found to favour the formation of Si crysta llites, together with a significant improvement of the phase segregation be tween Si grains and silica. The increase of the deposition temperature (T-S ) induced similar effects in such a way that the layer obtained with high P -H and T-S behaves as a pure silicon film with a refractive index close to 3.2. Thus, a 40-period Si-rich/silica multilayered system was fabricated by alternating the introduction and the switching off of the hydrogen flux. T he related electron microscopy image showed evidence of good quality multil ayers, which attests the reliability of the new method. (C) 2000 Elsevier S cience Ltd. All rights reserved.