Liquid helium temperature irradiation effects on the operation of 0.7 μm CMOS devices for cryogenic space applications

This paper describes the impact of ionising irradiation, performed at liquid helium temperatures (LHT) on the characteristics of transistors that have been fabricated in a 0.7 μm CMOS technology. First, a brief description of the cryogenic irradiation set-up and the pre- and post-irradiation characterisation will be given. Next, the behaviour of the input and output characteristics at LHT is described before and after y-exposure to a total dose of 15 to 30 krd(Si), which is the expected total dose range for the Herschel mission, scheduled for launch in the spring of 2007. The observed changes in the static device parameters at LHT will be compared with earlier results, obtained after room temperature irradiations. Overall, it is concluded that the components are sufficiently radiation hard for the considered space mission, from a viewpoint of Total Ionisation Dose damage.