Radiation-stimulated diffusion in single memory cells

Abstract

A model of radiation-stimulated diffusion (RSD) of phosphorus (P) in Si is proposed to interpret the results of the high-dose γ-irradiation of complementary metal-oxide-semiconductor (CMOS) memory transistors. The devices are irradiated with doses≥1 Mrad. A degradation of the parameters of memory transistors is explained on the basis of a model of RSD of impurities in the n–p junctions and a spreading of the impurity profiles. The RSD of P in Si occurs as a result of the ionization-induced decrease in potential barriers of diffusion hopping. A possible increase in the diffusion coefficient caused by the irradiation is estimated. An approach for the prediction of the exploitation resource of devices in extreme conditions is considered. In this case, the method of the similarity conversion is used. The approach is illustrated by a numerical example.

Keywords:

• memory transistors
• radiation-stimulated diffusion
• degradation

PACS :

• 61.80.-x
• 61.80. Az
• 61.82. Fk

Acknowledgements

This work was supported by the RHESSA program of the Chief Scientist Office at the Israeli Ministry of Industry and Trade. D.F. holds the Stephen and Edith Berger Chair in Physical Metallurgy.