A semiconductor device includes a first semiconductor chip including bitlines, wordlines, common source line, first bonding pads, second bonding pads, third bonding pads and memory cells, the memory cells being electrically connected to the bitlines, the wordlines, and the common source line, the first bonding pads being electrically connected to the bitlines, the second bonding pads being electrically connected to the wordlines, and the third bonding pads being electrically connected to the common source line; a second semiconductor chip including fourth bonding pads, fifth bonding pads, sixth bonding pads and an input/output circuit, the fourth bonding pads being electrically connected to the first bonding pads, the fifth bonding pads being electrically connected to the second bonding pads, the sixth bonding pads being electrically connected to the third bonding pads and the input/output circuit being configured to write data to the memory cells via the fourth bonding pads and the fifth bonding pads; a sensing line extending along an edge portion of the first semiconductor chip, an edge portion of the second semiconductor chip, or the edge portion of the first semiconductor chip and the edge portion of the second semiconductor chip; and a detecting circuit in the second semiconductor chip, the detecting circuit being configured to detect defects from the first semiconductor chip, the second semiconductor chip, or both the first semiconductor chip and the second semiconductor chip using the sensing line.