RADHARD 2019 - Abstract

Radiation Hardness Assurance

Dose Rate Effects in MOS Transistors

Varvara Bezhenova1, Alicja Michalowska-Forsyth1
Graz University of Technology, Institute of Electronics, Inffeldgasse 12/I, Graz 8010




Enhanced low dose rate sensitivity (ELDRS) has been a subject as well as a concern for radiation hardness assurance testing over several decades, in particular because of the underestimation of the effects in the accelerated testing [1]. ELDRS is prominent in bipolar transistors, where more pronounced gain reduction is observed at low dose rate. This phenomenon is related to thick layers of soft oxides [1]. Such oxides are also used in modern CMOS process nodes as shallow trench insulation. Thus the differences in oxide space charge build-up at low and high dose rates are worth considering also for the MOS transistors [2]. In this context, the to-date reported results on dose rate effects in MOS transistors over several CMOS process nodes will be reviewed [2, 3]. Also, our recent experimental results will be presented. The considerations for TID testing of MOS transistors will be discussed on an example of MOS transistor characteristics irradiated under two different dose rates.


[1] Pease, R. L., et al. (2008, September). ELDRS in bipolar linear circuits: A review. In 2008 European Conference on Radiation and Its Effects on Components and Systems (pp. 18-32). IEEE.

[2] Witczak, S. C., et al. (2005). Dose-rate sensitivity of modern nMOSFETs. IEEE transactions on nuclear science52(6), 2602-2608.

[3] Borghello, G., et al. (2018). Dose-rate sensitivity of 65-nm MOSFETs exposed to ultrahigh doses. IEEE Transactions on Nuclear Science65(8), 1482-1487.


This work has been carried out with financial support of Austrian Science Fund (FWF), project number T756 - N20.
We would also like to express our gratitude to MedAustron, Department of Non-Clinical research, for granting access to irradiation facility. Our special thanks go particularly to Thomas Schreiner for organizational support, and to Peter Kuess for his expertise in dosimetry.