A semiconductor memory is formed by stacking a plurality of substrates and memory cells on each substrate are connected by data dump lines. A switch may intervene between the memory cell and the data dump line. When data of each substrate is dumped by the data dump line, a problem of decrease in a speed and an increase in power consumption due to a parasitic component can be minimized. Further, a core circuit including the memory cell may be disposed on one substrate and a peripheral circuit unit may be disposed on the remaining substrates.