The Effect of Nitrogen Concentration at Oxynitride Gate Insulators Formed by 28N2 + Implantation into Silicon with Additional Conventional or Rapid Thermal Oxidation

Abstract

Silicon oxynitride (SiOxNy) insulators have been obtained by nitrogen ion implantation into Si substrates prior to conventional or rapid thermal oxidation. These films have been used as gate insulators in nMOSFETs and MOS capacitors. nMOSFET electrical characteristics, such as field effect mobility between 390 cm2/Vs and 530 cm2/Vs, and sub-threshold slope between 70 mV/decade and 150 mV/decade, were obtained. MOS capacitors were used to obtain capacitance-voltage (C-V) and current-voltage (I-V) measurements. The Equivalent Oxide Thickness (EOT) of the films were obtained from C-V curves, resulting in values between 2.9 nm and 12 nm. SiOxNy gate insulators with EOT between 2.9 nm and 4.3 nm have presented gate leakage current densities between 3 mA/cm2 and 50 nA/cm2. The electrical characteristics were compared and correlated with the nitrogen concentration profiles at SiOxNy/Si of the structures, obtained by Secondary Ion Mass Spectrometry (SIMS).