Semiconductor device and manufacturing method thereof

The invention discloses a semiconductor device and a manufacturing method thereof. In the technical scheme, the surface of a gate dielectric layer and the surface of a gate electrode are covered witha first dielectric layer, a light doping drain region and a light doping source region can be formed inside a substrate based on the first dielectric layer on the gate electrode and the surface of thegate electrode, the light doping source region and the light doping drain region are avoided from being diffused below the gate electrode, the distance between the light doping source region and thelight doping drain region can be increased, the problem of punch-through breakdown is avoided, the stray capacitance is reduced, and the operation frequency is improved. The source region and the drain region can be formed inside the substrate based on the first dielectric layer and a second dielectric layer on the gate electrode and the side wall of the gate electrode, and when the patterned second dielectric layer is form