Highly reliable ultra-thin SiO/sub 2/ films formed by rapid thermal processing

A reliable method of forming ultrathin SiO/sub 2/ films has been developed by using rapid thermal processing (RTP). In this study, both RTP oxidation (RTO) and RTP cleaning (RTC) are attempted. As a result, the dielectric strength of SiO/sub 2/ film is greatly improved by an RTO-1/RTC/RTO-2 cycle under reduced gas pressure. TDDB (time-dependent dielectric breakdown) measurements show that, with decreasing SiO/sub 2/ film thickness, short-time breakdown (<10/sup -1/ s) decreases drastically below 6 nm. High-resolution TEM (transmission electron microscope) measurements indicate that, by this RTP cycle, an extremely flat SiO/sub 2/-Si interface, ordered within one to two atomic layers, is obtained. Furthermore, in MOS capacitors having ultrathin SiO/sub 2/, the quantum oscillation in the Fowler-Nordheim tunneling current is clearly observed even at 300 K. It is confirmed that the proposed method is very effective in reducing defects such as broken Si-O bonds in bulk SiO/sub 2/ and/or SiO/sub 2/-Si interface.<>