Radiation-hard, high-voltage semiconductive device structure fabricated on SOI substrate
 Highly doped N- and P-type wells (16a, 16b) in a first silicon layer (16) on an insulator layer (14) of a SIMOX substrate (10). Complementary MOSFET devices (52,54,58,62) are formed in lightly doped N- and P-type active areas (22a, 22b) in a second silicon layer (22) formed on the first silicon layer (16). Adjacent active areas (22a, 22b) and underlying wells (16a, 16b) are isolated from each other by trenches (36,78) filled with a radiation-hard insulator material. Field oxide layers (42,64) are formed of a radiation-hard insulator material, preferably boron phosphorous silicon dioxide glass, over the surface of the second silicon layer (22) except in contact areas (68) of the devices (52,54,58,62). The devices (52,54,58,62) are formed in the upper portions of the active areas (22a, 22b), and are insensitive to the interfacial states of the SIMOX substrate (10). The buried wells (16a, 16b ) under the active areas (22a, 22b) have low resistance and enable the devices (52,54,58,62) to have high snap-back voltages. The absence of sharp edges also eliminates edge leakage upon high dosage irradiation, thus producing devices that are more radiation-resistant. 
Hughes Aircraft Company
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Mei F. Chen-Chi P.
Li Chang