Thin SiO sub 2 Films Grown for Brief Oxidation Times

Bulk p-type wafers prepared with HF and RCA cleaning were oxidized in an atmospheric pressure 0 sub 2 ambient with incandescent lamp heating. Minimal effective oxidation times of several seconds were obtained by rapidly heating wafers at rates up to 150C/sec and then turning off lamp power just as the desired peak temperature is approached. Cooling rates vary up to about 80C/sec. Film thicknesses obtained by this "spike" method increase from 1.5 nm for peak temperature of 1000C to 3.5 nm for peak temperature of 1200C. Oxidation kinetics was studied by varying processing time from a spike to a 20-s plateau. The activation energy is 2.5 eV for 1.5 nm to 5.0 nm films. Film thickness uniformity under 1% at one standard deviation over 150mm wafers, equivalent to 2.5C temperature variation, was obtained for spike oxidation by optimizing relative power ratios to the lamps. Measurements on blanket oxidized wafers by ellipsometry and corona-change Kelvin surface photovoltage techniques indicate equivalent physical properties over the range of oxidation times.