TOTAL DOSE RADIATION HARDNESS OF MOS DEVICES IN HERMETIC CERAMIC PACKAGES.

The total dose radiation hardness of hardened MOS transistors is experimentally shown to be degraded by hydrogen gas commonly trapped in hermetic ceramic package cavities. This introduces another variable to be considered in the manufacture and hardness assurance of total dose hardened integrated circuits. The observation also strengthens the link between hydrogen and interface state formation and adds to our understanding of hydrogen's role in ionizing radiation effects. We conclude from experiments in which hydrogen is diffused into irradiated oxides after Co(60) exposure that the diffusing hydrogen interacts with radiation induced damage to form interface states. Most models of hydrogen in radiation effects do not predict this. However, some previously proposed hydrogen mechanisms can be modified to explain our observations.