A CMOS transistor device including a tensile-stressed NMOS transistor and a PMOS transistor is disclosed. The NMOS transistor includes a gate, a gate oxide layer between the gate and semiconductor substrate, a silicon oxide offset spacer on sidewalls of the gate, N type lightly doped source/drain implanted into the semiconductor substrate next to the silicon oxide offset spacer, N type heavily doped source/drain implanted into the semiconductor substrate next to the N type lightly doped source/drain, and tensile-stressed silicon nitride layer covering the gate, the N type lightly doped source/drain, and the N type heavily doped source/drain.