Deposition of silicon oxide films on silicon using HelixJet – an atmospheric-pressure plasma jet process below 100 °C

• Silicon oxide deposition by an atmospheric-pressure plasma jet process at 70 °C. • Excellent interface to silicon right after deposition. • Post-annealing transforms the silicon oxide bulk into silicon dioxide. Silicon oxide films are widely applied for their superior dielectric, chemical and mechanic properties as well as for their resistance against reactive chemicals. Simultaneously, there is an increasing number of applications which demand a low deposition temperature. In this work, we compare the material properties of SiO x layers deposited on silicon at ca. 70 °C by HelixJet, an atmospheric-pressure plasma jet deposition (PA) using double helix electrodes, with those of SiO 2 layers thermally grown or deposited by plasma-enhanced chemical vapour deposition. According to cross-sectional transmission electron microscopy, the interface between the PA oxide and the Si substrate is, similar to the case of thermal oxide, smooth with no apparent defects. In addition, the electrically active interface defect density is only one order of magnitude higher than that of the interface between thermal oxide and Si. In contrast, the bulk of the PA oxide significantly differs from that of thermal oxide. Right after deposition, the PA oxide contains carbon and hydrogen in a concentration of several at%, and the SiO 2 network comprises several active centres. After furnace annealing, the formation of the SiO 2 network is completed and the optical and electrical properties of the PA oxide converge to that of thermal oxide.