Deuterium implantation at the back-end of line for the improvement of gate oxide reliability in nano-scale MOSFETs

This paper is focused on the improvement of MOS device reliability related to deuterium incorporation in gate oxide. The injection of D⁺ ions into the gate oxide film was achieved through low-energy implantation at the back-end of line (BEOL) for the purpose of the passivation of dangling bonds at SiO₂/Si interface and the generation of deuterium bonds in SiO₂ bulk. Device parameter variations, as well as the gate leakage current, depend on the degradation of gate oxide and, compared to corresponding hydrogen incorporation, are improved by deuterium incorporation. However, when the concentration of deuterium is redundant in gate oxide, excess traps are generated and degrade the performance. Our result suggests the novel method to incorporate deuterium in the MOS structure for the reliability.