A method for fabricating a stressed MOS device in and on a semiconductor substrate is provided. The method comprises the steps of forming a gate electrode overlying the semiconductor substrate and etching a first trench and a second trench in the semiconductor substrate, the first trench and the second trench formed in alignment with the gate electrode. A stress inducing material is selectively grown in the first trench and in the second trench and conductivity determining impurity ions are implanted into the stress inducing material to form a source region in the first trench and a drain region in the second trench. To preserve the stress induced in the substrate, a layer of mechanically hard material is deposited on the stress inducing material after the step of ion implanting.