Body-tied-to-source MOSFETs with asymmetrical source and drain regions and methods of fabricating the same

A method of fabricating MOSFET, the method comprising:

• forming a first semiconductor region of a first conductivity type on a substrate;
• forming a gate electrode on the first semiconductor region;
• doping the first semiconductor region with impurity ions of the first conductivity type to form an impurity-doped region of the first conductivity type on a first side of the gate electrode;
• removing a portion of the impurity-doped region of the first conductivity type and a portion of the first semiconductor region on a second side of the gate electrode to form respective trenches on the first and second sides of the insulated gate electrode;
• forming second and third semiconductor regions in the trenches;
• doping the second and third semiconductor regions with impurity ions of a second conductivity type to form a source region on the first side of the gate electrode, a drain region on the second side of the gate electrode and a body pattern underlying the gate electrode and having a first sidewall contacting the source region and the impurity-doped region of the first conductivity type and a second sidewall contacting the drain region;
• and
• forming a contact plug that extends through the source region to contact the impurity-doped region of the first conductivity type.