As disclosed herein, a semiconductor device includes a gate and a silicon substrate having a field region and an active region. A gate dielectric layer formed on the upper surface of the active region of the silicon substrate and on a gate dielectric layer. The gate may include first and second sidewall dielectric layers sequentially formed on sidewalls of the gate, epitaxial silicon layers formed at both sides of the gate on the silicon substrate, first LDD regions formed in the silicon substrate below the second sidewall dielectric layers, second LDD regions formed at one sides of the first LDD regions below the epitaxial silicon layers, source/drain regions formed under the second LDD regions, and silicide layers formed on the gate and the source/drain regions.