A semiconductor device includes a transistor and a memory pickup cell formed over a well in a substrate. The transistor includes a first fin having a first width and two first source/drain features on the first fin. The pickup cell includes a second fin having a second width and two second source/drain features on the second fin. The well, the first fin, the second fin, and the second source/drain feature are of a first conductivity type. The first source/drain features are of a second conductivity type opposite to the first conductivity type. The second width is at least three times of the first width. The pickup cell further includes a stack of semiconductor layers over the second fin and connecting the two second source/drain features.