Provided are a semiconductor device and a method for manufacturing the semiconductor device. The semiconductor device includes an isolation insulating film, an epitaxial silicon layer, a junction blocking insulating film, a gate stack, and source and drain junctions. The isolation insulating film is formed on a semiconductor substrate to define an active area. The epitaxial silicon layer is formed in the active area of the semiconductor substrate and surrounded by the isolation insulating film. The junction blocking insulating film is formed in the epitaxial silicon layer. The gate stack is formed over the epitaxial silicon layer so that the junction blocking insulating film is buried under approximately the center of the gate stack. The source and drain junctions are formed adjacent the sidewalls of the gate stack. Accordingly, a short circuit between source/drain junctions in a bulk area caused by the unwanted diffusion of the junctions can be prevented.