Semiconductor device with strained channel and method of fabricating the same

A method for fabricating a semiconductor device, the method comprising:

• forming a gate pattern over a substrate;
• etching the substrate at both sides of the gate pattern to form recess patterns each having a side surface extending below the gate pattern;
• forming a source and a drain by respectively filling the recess patterns using epitaxial growth;
• and
• forming a protection layer over a surface of the recess pattern through an epitaxial growth before forming the source and the drain,
• wherein the protection layer comprises a material having a lattice constant equal to that of the substrate.