RADIATION RESISTANT SEMICONDUCTOR ELEMENT

PURPOSE:To prevent the undesired conduction formation due a parasitic thyristor occurred between elements by forming a protective ring for surrounding one of CMOSFETs in a semiclosed curved surface connected with the same conductive type layer as the ring on the back surface of a semiconductor substrate. CONSTITUTION:P is selectively diffused to connect a protective ring 2 and a layer 3 to form a semiclosed curved surface 4 on both main surfaces of an N type Si substrate 1. Then, P is selectively diffused in an N type layer of the substrate 1 to form a source layer 6' and a drain layer 7', a P-well 5 is selectively formed in a region surrounded by the curved surface 4, N is diffused to form channel stoppers 8 in the layers 6, 7 and the substrate 1. Holes are opened at an SiO2 film 9 on the source and drain, electrode wiring patterns 10 are formed on a gate oxidized film to complete a CMOS device. According to this construction, even if electron and hole pair is generated due to the incident radiation, the low resistance semiclosed curved surface completely shields one FET. Accordingly, undesired conduction due to parasitic thyristor does not entirely occur.