Application of 100% ozone gas process to rapid low-temperature oxidation

A 100% ozone oxidation process has been applied for the first time to rapid low-temperature oxidation of silicon to fabricate device quality SiO₂ films. A new quartz cold wall-type furnace equipped with a halogen lamp heater was built for safe and efficient handling of 100% ozone gas supplied from a pure ozone generator which we have developed. The working pressure of the furnace was typically 900 Pa, which resulted in the growth of 4 nm SiO₂ film within 4 minutes at 400°C. A very low excitation energy observed for the SiO₂ film growth indicates that the actual reaction species in the process are active oxygen radicals generated from the thermal decomposition of ozone molecules at the sample surface. The electrical properties of ozone-oxidized SiO₂ films were evaluated by measuring the C-V and I-V characteristics of the MIS structure with Al electrodes. The films fabricated at 400-600°C with thickness of 5-11 nm all show properties matching the device quality, i.e. low interface state density (<5×10¹⁰ cm^-2eV^-1) and high breakdown voltage (>13 MVcm^-1).