Transistors and manufacturing methods thereof are disclosed. An example transistor includes a semiconductor substrate divided into device isolation regions and a device active region. The example transistor includes a gate insulating film formed in the active region of the semiconductor substrate, a gate formed on the gate insulating film, a channel region formed in the semiconductor substrate and overlapping the gate, and LDD regions formed in the semiconductor substrate and at both sides of the gate, centering the gate. In addition, the example transistor includes source and drain regions formed under the LDD regions, offset regions formed in the semiconductor substrate and between the channel region and LDD regions, and gate spacers formed at both sidewalls of the gate.