Patent ID: 7462930

Claim:
A stack chip having an upper semiconductor chip and a lower semiconductor chip stacked face-to-face, each semiconductor chip having: a semiconductor substrate having an active surface and a back surface opposite to the active surface; internal circuits formed in the active surface of the semiconductor substrate; chip pads connected to the internal circuits, the chip pads including input/output pads; input/output buffers connecting the input/output pads to the internal circuits; and connection pads formed on the active surface of the semiconductor substrate and connected to the chip pads, the connection pads including at least one input/output connection pad connected to the input/output buffer and the internal circuit, wherein the connection pads of the lower semiconductor chip are electrically connected to the connection pads of the upper semiconductor chip, and at least one semiconductor chip has first through electrodes connected to the chip pads, each first through electrode having a connection end exposed from the back surface of the at least one semiconductor chip.