Mapping CMOS radiation tolerance data on a 4-lane chart

An analysis is made of the growth of threshold voltage as a function of radiation dose in a very wide range of CMOS devices, all the way from low (kilorad) to very high (gigarad) doses. It is found that such results can be organized into four LANES OR CORRIDORS on the growth curve diagram. The resulting FOUR-LANE CLASSIFICATION is useful in selecting CMOS technologies and offers a new terminology for describing the radiation tolerance of ICs, namely "Old Soft, New Soft, Tolerant and Very Tolerant". The form of the lanes, though arrived at empirically, is consistent with the current theory of radiation response of MOS structures. The position of a device test result in this framework is a useful indication of the suitability of a device for use in a given radiation environment and could form tile basis of a "league table", used to assess the performance of "hardening laboratories" around the world and as a reference source for the properties of thin-film oxide materials.<
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