Process Controls for Radiation-Hardened Aluminum Gate Bulk Silicon CMOS

Optimized dry oxide processes have recently yielded notable improvements in CMOS radiation hardness. For these processes to be manufacturable, controls and screens are required to allow both manufacturer and user to guarantee survival of specific radiation environments. Four aspects of controlling a radiation hardened process are discussed. The electrical characteristics and constraints of a hardened technology are outlined. The statistical relations between radiation survival probability and process hardness capabilities are developed. The process steps which are key to achieving hardness are identified and the required controls on these steps are determined. Finally, the subject of hardness screening is explored to determine necessary actions, prerad and postrad, to insure that radiation requirements are met.