Systems and methods for fabricating semiconductor devices with dual-stress
layers using double-stress oxide/nitride stacks. A method comprises
providing NMOS and PMOS regions, selectively forming a dual-stack tensile
stress layer over the NMOS region by depositing a tensile silicon nitride
layer over the NMOS and PMOS regions, depositing a tensile silicon oxide
layer over the tensile silicon nitride layer, removing a portion of the
tensile silicon oxide layer from the PMOS region, and removing a portion
of the tensile silicon nitride layer from the NMOS region and selectively
forming a dual stack compressive stress layer over the PMOS region by
depositing a compressive silicon nitride layer over the NMOS and PMOS
regions, depositing a compressive silicon oxide layer over the
compressive silicon nitride layer, removing a portion of the compressive
silicon oxide layer from the NMOS region, and removing a portion of the
compressive silicon nitride layer from the NMOS region.