Impact of heavy-ion strikes on minimum-size MOSFETs with ultra-thin gate oxide

We present new original experimental results on the effects produced by single heavy-ion strikes on minimum-size MOSFETs manufactured in a 0.1-mu m CMOS technology. We show that, whereas large-width samples do not suffer from any particular degradation when struck by a single ion, minimum size devices, which are the real building block of modern digital circuits, display small but significant changes in the electrical characteristics. In particular, we identify and classify the different types of degradation occurring after irradiation with high-LET particles and attribute them to ion strikes occurring in different parts of the MOSFET: gate oxide, LDD spacers, and STI. Even though the observed changes do not compromise the device functionality, they clearly indicate that, as the feature size is scaled into the decananometer range, single heavy-ion strikes will have a growing effect on digital circuits.