High quality 4 nm gate dielectrics prepared at low pressure in oxygen and nitrous oxide atmospheres

Thin silicon oxide nitridation in N 2 0 has been demonstrated to improve the dielectric characteristics in terms of charge to breakdown and trapping under current injection. For the first time we report fairly extensive experimental results of the thermal N 2 0 oxidation of silicon at low pressure. The results clearly indicate a higher oxidation rate in N 2 0 atmosphere than in 0 2 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 devices have been fabricated in a N 2 O, O 2 :N 2 O and O 2 atmosphere at reduced pressure and electrically characterized. The low pressure N 2 0 oxides exhibit better oxide homogeneities across the wafer, higher charge to breakdown values and dielectric breakdown fields than atmospheric pressure oxides.