High quality 4 nm gate dielectrics prepared at low pressure in oxygen oxide atmospheres
Thin silicon oxide nitridation in N20 has been demonstrated to improve the dielectric characteristics in terms of charge to break-down and trapping under current injection. For the first time we report fairly extensive experimental results of the thermal N2O oxidation of silicon at low pressure. The results clearly indicate a higher oxidation rate in N2O atmosphere than in O2 atmosphere at a pressure of 4.5 Torr, in contrast to the rates at atmospheric pressure. Ultrathin (< 5 nm) dielectric films for the application in metal-oxide-semiconductor (MOS) devices have been fabricated in a N2O, O2: N2O and O2 atmosphere at reduced pressure and electrically characterized. The low pressure N2O oxides exhibit better oxide homogenities across the wafer, higher charge to breakdown values and dielectric breakdown fields than atmospheric pressure oxides.