Semiconductor cell and its forming method and operating method are provided. The semiconductor device includes: a substrate with a first region; a first nanopillar, formed on a substrate surface of the first region and perpendicular to the substrate surface; a first source/drain region, formed at a bottom of the first nanopillar and in a portion of the substrate in the first region; a first gate structure, surrounding the first nanopillar and formed on the first source/drain region; and a second source/drain region, formed at a top of the first nanopillar and on the first gate structure.