SEMICONDUCTOR DEVICE

PURPOSE:To enable to set the capacity between a collector and an emitter to the optimum value and to improve the power gain and the stability coefficient of a base-grounded high frequency transistor circuit by disposing a shielding impurity region of reverse type to a semiconductor substrate connected to a base electrode through an insulating film under an emitter electrode. CONSTITUTION:P type impurity is diffused in an N type semiconductor substrate 11 to become a collector to form a base region 12, and an N type impurity is diffused in the region 12 to form an emitter region 13. A shielding impurity region 14 of P type is formed on the substrate 11 to becomes a bonding pad forming portion of the emitter electrode. A insulating film I is formed on the substrate 11, patterned to form contacting holes opened at the base region 12, the emitter region 13, and the impurity region 14. Then, aluminum is deposited on the film I , patterned to form an emitter electrode 2E which includes a base electrode 2B connected to the region 12 and a bonding pad 2E' connected to the region 13 through the holes.