An SRAM cell structure containing a PFET gate dielectric having a thicker
effective oxide thickness (EOT) than an NFET gate dielectric and methods
of manufacturing the same is provided. The PFET gate dielectric and the
NFET gate dielectric may be silicon oxynitride layers, CVD oxide layers,
or high-K dielectric layers having different thicknesses. The PFET gate
dielectric may be a stack of two dielectric layers and the NFET gate
dielectric may be one of the two dielectric layers. The greater EOT of
the PFET gate dielectric produces reduction of the on-current of the
pull-up PFETs for optimal SRAM performance.