Enhanced low dose rate sensitivity (ELDRS) in a voltage comparator which only utilizes complementary vertical NPN and PNP transistors

For the first time, enhanced low dose rate sensitivity (ELDRS) is reported in a vertical bipolar process. A radiation hardness assurance (RHA) test method was successfully demonstrated on a linear circuit, the HS139RH quad comparator, and its discrete transistor elements. This circuit only uses vertical NPN and PNP transistors. Radiation tests on the HS139RH were performed at 25/spl deg/C using dose rates of 50 rd(Si)/s, 100 mrd(Si)/s and 10 mrd(Si)/s, and at 100/spl deg/C using a dose rate of 10 rd(Si)/s. Tests at dose rates of 50 rd(Si)/s at 25/spl deg/C and 10 rd(Si)/s at 100/spl deg/C were performed on discrete vertical NPN and PNP transistor elements which comprise the HS139RH. Transistor and circuit responses were evaluated. The die's passivation overcoat layers were varied to examine the effect of removing a nitride layer and thinning a deposited SiO/sub 2/ (silox) layer.