A method of fabricating a semiconductor device is provided. First, a semiconductor structure is provided, and the semiconductor structure includes a buried dielectric layer, a first gate structure disposed on a front-side of the buried dielectric layer, and a first source/drain region and a second source/drain region disposed between the buried dielectric layer and the first gate structure. Then, a trench is formed in the buried dielectric layer. Afterwards, a conductive layer is formed on the buried dielectric layer and in the trench. Finally, the conductive layer is patterned.