Charge yield for cobalt-60 and 10-keV X-ray irradiations of MOS devices

The radiation response of MOS devices exposed to /sup 60/Co and low-energy ( approximately 10 keV) X-ray irradiation is evaluated as a function of electric field during exposure. Improved charge yield estimates are obtained for /sup 60/Co irradiations at fields below 1 MV/cm by matching voltage shifts due to oxide-trap and interface-trap charge to an E/sup -0.55/ electric field dependence. Combining these improved charge yield estimates and calculated dose enhancement factors, the relative response of X-ray to /sup 60/Co irradiations is accurately predicted for oxide electric fields from 0.03 MV/cm to 5.0 MV/cm. The ability to predict the relative response to X-ray to /sup 60/Co irradiations-should speed acceptance of X-ray testers as a hardness assurance tool. >