Low-leakage and highly-reliable 1.5 nm SiON gate-dielectric using radical oxynitridation for sub-0.1 μm CMOS

We have developed a low-leakage and highly-reliable 1.5 nm SiON gate-dielectric by using radical oxynitridation. In this development, we introduce a new method for determining ultra-thin SiON gate-dielectric thickness based on the threshold voltage dependence on the substrate bias in MOSFETs. It was found that radical oxidation followed by radical nitridation provides 1.5 nm thick SiON in which leakage current is two orders of magnitude less than that of 1.5 nm thick SiO2 without degrading device performance. The 1.5 nm thick SiON was also found to be ten times more reliable than 1.5 nm thick SiO2.