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

Extensive experimental results are reported about the rapid thermal O-2 and N2O oxidation of silicon at pressures as low as 25 Torr. The decrease of the oxidation rate in N2O is smaller than in O-2 atmosphere with decreasing pressure. Therefore, almost equal oxidation rates for the oxidation in O-2 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. (C) 1998 Elsevier Science Ltd.