Semiconductor device and a method of fabricating the same with increased effective width of the channel without increasing the width of the gate active region

A method of fabricating a semiconductor device, comprising:

• forming a plurality of recesses in the substrate;
• forming a gate structure on the substrate, wherein the gate structure covers the plurality of recesses and a surface of the substrate between the plurality of recesses, wherein the gate structure comprises:
• a gate dielectric layer covering bottom surfaces and sidewalls of the plurality of recesses and the surface of the substrate between the plurality of recesses;
• and
• a gate conductive layer formed on the gate dielectric layer, filling in the plurality of recesses and covering the surface of the substrate between the plurality of recesses;
• forming a first doped region and a second doped region at two sides of the gate structure,
• wherein a length of the plurality of recesses in a first direction is greater than a length of the gate structure in the first direction;
• and forming a plurality of spacers on sidewalls of the gate structure, wherein sidewalls of a plurality of ends of each recess in the first direction and a top surface of the substrate are covered by the corresponding spacers.