Systematic investigation of monolithic bipolar transistors irradiated with neutrons, heavy ions and electrons for space applications

In this paper, experimental results of radiation effects on a BiCMOS high speed commercial technology, manufactured by ST-Microelectronics, are reported after irradiation with 9.1 MeV electrons. The data are compared with those previously obtained by irradiations with fast-neutrons, 12C-, 13C-, Ar- and Kr-ions. Fast-neutrons, as well as other types of particles, produce defects, mainly by displacing silicon atoms from their lattice positions to interstitial locations, i.e. generating vacancy–interstitial pairs, the so-called Frenkel pairs, which results in creating recombination centers. As a consequence, the lifetime of the minority-carriers in the base is decreased and the common-emitter current gain (β) is degraded. The gain degradation was investigated for collector current Ic between 1 μA and 1 mA. The linear dependence of Δ(1/β) = 1/βirr − 1/β (where βirr and β are the gain after and before the irradiation) as a function of the concentration of Frenkel pairs was confirmed. The bipolar transistors made on this technology have shown to be particularly radiation resistant. Base and collector currents were systematically investigated, as well as, the effect of self-annealing.