The Response of MOS Devices to Dose-Enhanced Low-Energy Radiation

A series of experiments has been performed to investigate the response of MOS structures to low-energy radiation. A 10-keV x-ray source was used to irradiate MOS capacitors through a gold/aluminum bilaminate. As expected, the device response when the gold side of the bilaminate faces the device is enhanced strongly with respect to its response when the aluminum side of the bilaminate faces the device. The degree to which the enhanced radiation affects the device response, as determined by the buildup of oxidetrapped charge, depends on the thickness of the gate insulator and the thickness of the capacitor gate in ways similar to those expected from previous work. In addition, striking dependences of the enhanced device response on the energy of the incident radiation, and on the magnitude and direction of the electric field across the gate insulator during the irradiation were observed. These results may provide new insights into the details of the interaction of low-energy radiation with MOS devices.