Selective Rapid Thermal Oxidation of Silicon vs. Tungsten using Oxygen in Hydrogen

Process behavior associated with the selective oxidation of silicon (Si) vs. tungsten (W) by oxygen (O₂) in hydrogen (H₂) has been studied in Applied materials radiancetrade chamber. New data is obtained for SiO₂ growth on Si (100) at sub-atmospheric pressure and 750-950degC, with the H₂ percentage in the range of 80% to 95%. This SelOx process is a novel extension of applied materials proven low pressure RadOxtrade solution for oxidation applications. The selectivity window for oxidizing Si but not W is determined by Reflectivity measurement of the W film to check for any degradation, cross checked with TEM observations. When W films were processed outside the selectivity window, both W loss and W oxidation were observed. Oxide thicknesses suitable for advanced memory & logic sidewall applications (20-40 Aring on Si-100) are achievable, while processing within the W selectivity window.