Measurement of SEU Thresholds and Cross Sections at Fixed Incidence Angles

Current SEU testing and analysis techniques have as basic assumptions that the charge deposited at a junction depends linearly on the linear energy transfer (LET) of the ion and the pathlength of the ion through an imagined parallelepiped that represents the depletion region. This study tests these assumptions for two bipolar parts, AMD 27LSOO and Fairchild 93L422, by irradiating at fixed angles while varying the LET of two ion species. It was found that the 27LSOO shows a pronounced ion species dependence, and may show a deviation of deposited charge from the usual inverse-cosine times a fixed depletion depth, while the 93L422 exhibited the expected inverse-cosine dependence and no ion species dependence.