In this work we assess the effect of low-energy nitrogen implantation for dual-gate oxide thickness formation. A comparison of transistor performance, I If noise and oxide reliability is made between 3.5 nm thick oxides fabricated by nitrogen ion implantation followed by dry oxidation and a reference oxide grown by dry oxidation followed by annealing in nitric oxide (NO oxide). The results show that the ion-implanted samples have lower oxide charges, lower 1/f noise, good reliability and sufficient boron penetration immunity. (C) 2004 Elsevier Ltd. All rights reserved.