Investigations of an Irradiate-Anneal Technique for Neutron Hardness Assurance of Power Transistors

The results of an irradiate-anneal study for screening power transistors for neutron degradation are reported in this paper. The results of this study on 100 RCA TA8007 power devices indicated that very good predictions could be made for the neutron gain degradation, where the gains were measured within the capability of standard probe measurements. The observed neutron degradation of the package transistor gains closely matched that of the same transistors measured at the wafer stage, indicating that "soft" devices would be rejected prior to packaging if screens were imposed at the wafer stage. The optimum annealing condition for an irradiation fluence of 3.62 × 1013 n/cm2 (E > 10 keV) was 350° C for four hours. Failure analyses (MTBF tests) indicated that the reliability of those devices are practically unaffected by the additional stresses required to implement an irradiate-anneal hardness assurance program.