Synergistic Effect of Neutron and Gamma Irradiation on CMOS Integrated Circuits

Abstract

To investigate the interaction between the total ionizing dose (TID) effect and displacement damage, this paper presents the experiment results of several CMOS integrated circuits’ radiation effect in a mixed neutron and gamma ray environment. The electrical and functional tests were made in four irradiation environments: 1. neutron (high neutron/gamma ratio); 2. gamma ray; 3. combined irradiation of neutron and gamma ray (low neutron/gamma ratio); 4. TID test after neutron irradiation. All the parameters were tested online. Compared with the single radiation environments, results show that the mixed neutron and gamma irradiation can induce a synergistic effect on the samples. In the neutron and gamma synergistic irradiation, the devices exhibit considerably severer degradation. The synergistic effect occurs while neutron and gamma exist synchronously. Where the percentage of gamma is comparable or larger than neutron at the levels of concern, one can expect synergistic effects will occur in the CMOS devices, and the TID effects should not be decoupled from nonionizing or displacement damage.