Hydrogen diffusion through silicon/silicon dioxide interfaces

In order to improve the electrical properties of semiconductor devices residual defects have to be passivated. In c-Si metal-oxide-semiconductor devices, these defects are located at the Si/SiO2 interface, while in polycrystalline silicon thin-film transistors, in addition to interface defects, grain-boundary defects have to be passivated. In both device structures, H has to diffuse through numerous layers of oxides, silicon, and possible surface barriers. To improve the H passivation efficiency, it is important to understand H transport through Si/SiO2 interfaces. H transport through the oxide was studied by measuring the changes of the flux through the oxide as a function of time, temperature, and oxide thickness. The oxide layer reduces the H flux into the underlying layers by more than four orders of magnitude. The temperature dependence of the H flux was found to be independent of the oxide thickness. This indicates that the striking decrease in Il flux is not due to an increase in barrier height. (C) 2000 American Vacuum Society.