The application of nitrogen ion implantation in silicon technology

Abstract

During the past decade numerous studies have dealt with the effects of nitrogen ion implantation in silicon, such as insulating properties, oxidation inhibition, crystal regrowth and doping effects. However, the lack of detailed knowledge of nitrogen concentration profiles in silicon has been an obstacle to elucidating the mechanism of some of these effects and finding the optimum conditions for their applications in semiconductor device technology. Recently we found 15N (p, αγ) 12C resonant nuclear reaction analysis to provide a valuable technique to measure nitrogen concentration profiles. It appears that remarkable redistributions of nitrogen profiles in silicon take place during annealing and oxidation, which result in the formation of extremely thin nitrogen rich layers at the Si-SiO 2 interface. From these observations it is explained that moderate doses of nitrogen ions can induce an oxidation resistance which is sufficient to provide self-aligned contact windows in MOS technology. Finally some of the results on nitrogen ion implantation reported in the past decade will be discussed in view of these new analyses.