Wear-out, ESD, and radiation
Reliability and Radiation Effects on Advanced CMOS Technologies



We investigate synergetic effects between radiation and other reliability issues:

Total ionizing dose and wear-out

We are studying synergic effects between radiation-induced and stress-induced defects in deep sub-micron devices employed in harsh radiation environment.
We explore these interactions combining accelerated electrical stress and irradiation with X-ray, protons, and heavy ions. Fowler-Nordheim (FN), Channel Hot Carrier (CHC), and Negative Bias Temperature Instability (NBTI) measurements are performed on advanced CMOS technologies in order to study the response of gate-oxides. We found that irradiation bias plays an important role in CHC degradation after total dose accumulation in 130-nm technology, due to a strong interaction between hot electrons and radiation induced defects generated in the lateral isolation (STI).
The influence of device geometry on stress outcome after irradiation is under investigation in order to understand and clarify the physics of hydrogen release. We irradiated and CHC-stressed CMOS transistors with enclosed layout (ELT), founding a different behavior compared to conventional samples with open layout. Moreover the hydrogen released during radiation exposure, may interact with subsequent accelerated electrical stress bringing to different and unexpected results.

ESD effects in irradiated CMOS devices

We study, in collaboration with Prof. G. Meneghesso's group, two different aspects concerning the interaction between electrostatic discharges (ESD) and ionizing radiations: on one hand on the ionizing radiation effects in ESD protection structures and on the other hand the ESD effects in irradiated CMOS devices.

The ESD sensitivity of irradiated input/output buffer pins of advanced CMOS circuits, for example based on planar SOI and multi-gate FinFET technologies, is a reliability issue taken in consideration in our group.
We demonstrated that heavy-ion strikes on floating MOSFETs produce only modest changes in the device electrical characteristics, but may decrease the ESD breakdown voltage for events at the gate. In addition, after irradiation the probability of filament formation after gate ESD strongly increases. Our results indicate that the combination of ESD and radiation damage may have a non-marginal impact on the reliability of advanced CMOS devices in space electronics



Previous X-ray irradiation can worsen the degradation under hot carrier injection.