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Quantitative risk assessments are presented for two radiation-hardened MOSFETs (Harris FSL11A0 and FRL11A0) using an extracted expression, integral flux curves representing different conditions, and experimentally-determined signature curves taken at different ion impact angles. The effectiveness of certain parameters including the selected orbit, spacecraft shielding thickness, drain and gate biases, device hardness, and time of exposure are discussed. Failures are studied using normalized Monte Carlo simulations validated by statistical methods. These validated Monte Carlo simulations are then used to extract and present an extracted expression. The concept of a lethal ion rate is discussed. Single event gate rupture (SEGR) failure thresholds at different ion impact angles are measured and reported on the Harris FSL11A0 and FRL11A0 (radiation-hardened vertical MOSFETs having similar layouts but with different SEGR sensitivities). Integral flux curves are presented for various orbits and conditions. Predictions of very early failures are performed using the extracted expression, the integral flux curves, and the new signature curves. Based upon these predictions, the influence of selected parameters are evaluated.
Date of Publication: Dec. 1999