4 nm Gate dielectrics prepared by RTP low pressure oxidation in O2 and N2O atmosphere

Extensive experimental results are reported about the rapid thermal O₂ and N₂O oxidation of silicon at pressures as low as 25 Torr. The decrease of the oxidation rate in N₂O is smaller than in O₂ atmosphere with decreasing pressure. Therefore, almost equal oxidation rates for the oxidation in O₂ and N₂O atmospheres were found at the lowest investigated pressure of 25 Torr. In addition, the low pressure oxides show better oxide homogeneities across the wafer; this is especially true for N₂O oxides. Ultra-thin (down to 4 nm) dielectric films for application in metal-oxide-semiconductor (MOS) devices have been fabricated and electrically characterized. The low pressure oxides exhibit higher charge to breakdown values and dielectric breakdown fields than atmospheric pressure oxides.