Study on the characteristics of SiO2 films prepared by hydrogen-assisted low-pressure radical oxidation using batch-type equipment with a 100-wafers of 300-mm-diameter capability

Hydrogen-assisted radical oxidation at reduced pressure (less than 200 Pa) was investigated using batch-type furnace equipment with a capability of more than 100 wafers of 300 mm in diameter in a batch. The oxidation behavior revealed that the oxidation was dominated by reactive oxygen radicals, and the Arrhenius plot indicated that the activation energy of the process was around 0.3 eV. The uniformity of the oxide film was improved to less than 2 % by modifying the gas nozzles and by rotating the wafer boat during the process. Radical oxidation showed superior bulk and interfacial properties to conventional oxidation, such as reduced dangling bonds, reduced interfacial transition-layer thickness, and reduced interface roughness. Furthermore, a more diffusion-limited oxidation behavior caused by oxygen radicals suppressed the bird's beak profile at the pattern edge and the crystallographic orientation dependency. An enhancement of the electrical characteristics, including the gate oxide integrity (GOI) in terms of charge-to-breakdown (Q{sub BD}) and a reduction of the threshold voltage variation, was consistent with the interpretation of the physical properties of radical oxidation.