Study for the Reliability of Nano-Scale MOS Devices that Experienced Implantation of Hydrogen or Deuterium at the Back-End of the Process Line

Abstract

This paper is focused on the improvement of MOS device reliability related to hydrogen or deuterium atoms. The injection of these atoms into the gate oxide film was achieved through lowenergy implantation at the back-end of a line for the purpose of passivation of dangling bonds at the SiO2/Si interface. Experimental results are presented for the degradation of the 3-nm-thick gate oxide (SiO2) under both hot-carrier-injection (HCI) and constant voltage stresses using p-and n-MOSFETs. Device parameters, 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. The Si-D bonds (instead of Si-H) in the SiO2 film were found to play a major role in suppressing the generation of oxide traps. However, when the concentration of deuterium is redundant in the gate oxide, excess traps are generated and degrade the performance. Our result suggests a novel method to incorporate deuterium in the MOS structure for reliability.