We have developed single-wafer furnace rapid thermal process (RTP) modules for thermal oxidation of silicon substrates. Dry oxides 20 Angstrom and wet oxides 25 Angstrom thick were grown on both 200 and 300 mm diam Si wafers with excellent thickness uniformity and repeatability. Thermal oxynitridation in nitric oxide (NO) and reoxidation can provide sub-25 Angstrom oxides. The thermal stress within the silicon wafer was maintained at low levels. It is demonstrated that high quality thin gate oxide films, comparable to those grown in a conventional furnace, can be generated without the drawbacks associated with lamp-based RTP systems. (C) 2002 The Electrochemical Society.