Impact of radical oxynitridation on characteristics and reliability of sub-1.5 nm-thick gate-dielectric FETs with narrow channel and shallow-trench isolation

We have demonstrated that oxynitridation using radical-O and -N improves reverse narrow channel effects (RNCE) and reliability in a sub-1.5 nm-thick gate-SiO/sub 2/ FETs with narrow channel and shallow-trench isolation (STI), which is suitable for high-density SRAM and logic devices. The STI structure needs a uniform gate-dielectric on the Si surface with various orientations. Oxidation using radical-O forms the uniform SiO/sub 2/ on the Si<100> and Si<111> surfaces and suppresses RNCE in a sub-1.5 nm-thick gate-SiO/sub 2/ FET with STI. Nitrifying the SiO/sub 2/ using radical-N increases the physical thickness while maintaining the oxide equivalent thickness on the Si<111> surface as well as the Si<100> one and, thus, producing a low-leakage and highly reliable sub-1.5 nm-thick gate-SiON.