Differences Between Charge Trapping States in Irradiated Nano-Crystalline HfO and Non-Crystalline Hf Silicates

• Published in: IEEE transactions on nuclear science Vol. 53; no. 6; pp. 3644 - 3648
• Main Authors: Lucovsky, G., Fleetwood, D.M., Lee, S., Seo, H., Schrimpf, R.D., Felix, J.A., Luning, J., Fleming, L.B., Ulrich, M., Aspnes, D.E.
• Format: Journal Article
• Language: English
• Published: IEEE 01-12-2006
• Subjects: Charge carrier processes; Charge measurement; Charge trapping; Current measurement; Dielectric measurements; Electric variables measurement; Electron traps; Grain boundaries; Hafnium oxide; high- kappa dielectrics; hole traps; metal-oxide-semiconductor (MOS) devices; oxide-trap charge; Oxygen; Spectroscopy
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2006.886211

This paper provides an explanation for qualitative differences between radiation-induced charge trapping states in nano-crystalline HfO 2 and non-crystalline Hf silicate alloys in high-kappa gate stacks by combining electrical measurements with spectroscopic studies and theory. Differences in the observed electrical response to X-ray and gamma-ray irradiation are consistent with fundamental differences in electronic structures between high-kappa dielectrics that are nano-crystalline and have a film thickness in excess of 4 nm, and high-kappa dielectrics that are non-crystalline and devoid of grain boundaries. Oxygen vacancy and interstitial defects are shown to be natural candidates for the electron and hole traps in these high-kappa dielectrics