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.