A method of manufacturing a stacked semiconductor device having two or more wafers may include forming a conductor on an upper wafer, the conductor configured to electrically connect input terminals together that have no input protection circuit against ESD; forming front side micro-bumps on a front side of the upper wafer, the front side micro-bumps configured to electrically connect to back side micro-bumps on the upper wafer; forming a TSV structure, the TSV structure configured to facilitate electrical connections between the front and the back side of the upper wafer; forming back side micro-bumps on the back side of the upper wafer, the back side micro-bumps configured to electrically connect with front side micro-bumps on the lower wafer; stacking the upper wafer on the lower wafer; and separating the conductor such that each of the input terminals are electrically independent from other ones of the input terminals.