The present invention provides a method for fabricating improved integrated circuit devices. The method of the present invention enables selective hardening of gate oxide layers and includes providing a semiconductor substrate having a gate oxide layer formed thereover. A resist is then formed over the gate oxide layer and patterned to expose one or more areas of the gate oxide layer which are to be hardened. The exposed portions of the gate oxide layer are then hardened using a true remote plasma nitridation (RPN) scheme or a high-density plasma (HDP) RPN scheme. Because the RPN scheme used in the method of the present invention runs at low temperature, the patterned resist remains stable through the RPN process, and those areas of gate oxide layer which are exposed by the patterned resist are selectively hardened by the RPN treatment, while those areas covered by the patterned resist remain unaffected. The method of the present invention is extremely adaptable and may further include additional thermal oxidation steps used to thicken non-hardened portions of the gate oxide layer, as well as additional masking, and hardening steps, which may provide multiple hardened or non-hardened portions of varying thicknesses within a single gate oxide layer. Thus, the method of the present invention may be used to fabricate an IC device having selectively hardened N-channel and P-channel devices having gate oxides of varying thickness.