Characterization of radiation effects on trench-isolated bipolar analog microcircuit technology

Radiation effects on trench-isolated bipolar analog microcircuits have been characterized through measurement of neutron damage, long-term ionizing radiation damage, transient photoresponse, and pulsed radiation-induced latchup. The characterization was done to provide basic information on the hardness of the technology for potential system application. The principal means of evaluation was through characterization of process-control and custom test chips. Results of the test chip characterization were compared to radiation effects characterization of basic microcircuits of identical process technologies. The goal of the characterization was to determine if there were any surprises in the radiation susceptibility. None was found in the displacement damage, transient photoresponse, or radiation-induced latchup. Displacement damage effects are determined by transistor gain degradation. Transient photoresponse is dominated by the substrate photocurrent. The presence of deep trenches does not prevent latchup but latchup can be mitigated by the process doping profile. There were some questions remaining associated with the long-term ionization radiation damage. Test chip data were not completely consistent and some further investigation is necessary