Impact of irradiations performed at liquid helium temperatures on the operation of 0.7 μm CMOS devices and read-out circuits

It has become dear that the effect of total ionizing dose (TID) and displacement damage on device performance strongly depends on its operation temperature. It is the aim of this paper to describe a dedicated set-up for executing biased irradiation testing at low temperatures. As a test vehicle prototype chips for the HERSCHEL mission, fabricated in a standard 0.7 μm CMOS technology, have been used. In order to get a better insight in the fundamental radiation damage mechanisms, also simple test structures (transistors) have been exposed to the same radiation dose of ⁶⁰Co γ's or 60 MeV protons. It is shown that from a viewpoint of TID damage the read-out circuits will survive the mission's estimated total dose. There is a good agreement between the observed circuit performance shift and the parameter shift derived from the n-and pMOSFETs.