Disclosed are a semiconductor device and a method for manufacturing the same. The method includes forming a gate layer on a semiconductor substrate; forming a first oxide layer on the semiconductor substrate; forming a second oxide layer on the first oxide layer; exposing the first oxide layer by removing the second oxide layer other than on side surfaces of the gate layer by etching using a photoresist as a mask; and forming junctions in source/drain regions by implanting a high concentration of N-type ions and/or a high concentration of P-type ions using the second oxide layer as a sidewall mask.