A memory device including a stack semiconductor device including; an upper substrate vertically stacked on a lower substrate, the upper substrate including N upper through-silicon vias (UTSV) and upper driving circuits, and the lower substrate including N lower through-silicon vias (LTSV) and lower driving circuits, wherein each one of the upper driving circuits is stagger-connected between a Kth UTSV and a (K+1)th LTSV, where ‘N’ is a natural number greater than 1, and ‘K’ is a natural number ranging from 1 to (N−1).