A high quality ultra-thin plasma nitrided oxide (EOT~12.5Å) is fabricated by the clustering of gate dielectric process in a production-worthy tool. Compared to conventional plasma nitrided oxide process, cluster process shows 1.2 Å reduction in inversion oxide thickness (Tox_inv) due to less moisture induced-oxide re-growth and nitrogen out diffusion. In addition to significant Tox_inv reduction, cluster process offers devices that exhibit better device performance and superior reliability characteristics in terms of SCE, Vt roll-off, DIBL and 2X lifetime improvement in NBTI, thus making it very promising for sub-90nm CMOS.