Backside illuminated CMOS image sensors for extreme ultraviolet applications

In this work, we report the performance of 4-transistor backside-illuminated CMOS image sensors (4T BSI-CIS) in the extreme ultraviolet (EUV) range. Both, bulk thinned as well as silicon-on-insulator (SOI) image sensors have been characterized. The sensors have been backside passivated by ion-implantation and laser annealing. It is found that the sensors exhibit sensitivity that is close to the theoretical maximum in the targeted EUV range, with a peak quantum yield at 13.5 nm of more than 20 electrons per photon. The sensitivity degradation of these sensors to a total exposure level of 0.96 J/cm² is found to be minimal: in the 1 % - 6 % range.