| 摘要 |
PURPOSE:To lower the probability of defects to the extent that practically there is no problem by setting the specific resistance of a wafer to a specific value to increase a breakdown resistance against cosmic rays. CONSTITUTION:A design for the direction of the thickness of a wafer is at first to determine a rated voltage and to determine the specific resistance and the thickness of a wafer to satisfy the rated voltage in the whole range of a guaranteed temperature. The thickness of a wafer is determined by adding a margin according to each device to the width of a depletion layer. A semiconductor device is a wafer W3 including a PN junction, and the specific resistance of the wafer W3 is set to a rated voltage/17 <= the specific resistance rho of the wafer W3 W3 a rated voltage/12, and the thickness of the wafer W3 is set to be nearly equal to the width of a depletion layer of a PN junction in the vicinity of the rated voltage so as to punch through in the vicinity of the rated voltage. Further, a shield member for shielding the incidence of cosmic rays upon a semiconductor element is provided at least in the direction of the zenith of the semiconductor element, so that the breakdown resistance against cosmic rays may be increased. |
