Patent ID: 8441278

Claim:
A stacked semiconductor device, comprising: a first semiconductor device including a signal line, a power supply line, a ground line, and a first semiconductor chip having a transistor circuit connected to the signal line, a first protection diode connected between the signal line and the power supply line, and a second protection diode connected between the signal line and the ground line; and a second semiconductor device including a signal line, a power supply line, a ground line, and a second semiconductor chip having a transistor circuit connected to the signal line, a first protection diode connected between the signal line and the power supply line, and a second protection diode connected between the signal line and the ground line, wherein the second semiconductor device is stacked on the first semiconductor device via a connection portion such that each of the signal line, the power supply line, and the ground line is connected respectively, wherein the power supply line connected to the first and second semiconductor chips is used in common, and a forward ON voltage of the first and second protection diodes of the first semiconductor chip is set higher than a forward ON voltage of the first and second protection diodes of the second semiconductor chip.