The present disclosure provides a semiconductor device and a manufacturing method thereof, and an electronic device including the semiconductor device. The semiconductor device includes: a substrate; an active region including a first source/drain region, a channel region and a second source/drain region stacked sequentially on the substrate and adjacent to each other; a gate stack formed around an outer periphery of the channel region; and spacers formed around the outer periphery of the channel region, respectively between the gate stack and the first source/drain region and between the gate stack and the second source/drain region; wherein the spacers each have a thickness varying in a direction parallel to a top surface of the substrate.