DocumentCode :
901164
Title :
Generation of Oxide Charge and Interface States by Ionizing Radiation and by Tunnel Injection Experiments
Author :
Knoll, M. ; Braunig, D. ; Fahrner, W.R.
Author_Institution :
Hahn-Meitner-Institute for Nuclear Research Berlin - Department D - Glienicker Strasse 100, 1000 Berlin 39, West Germany
Volume :
29
Issue :
6
fYear :
1982
Firstpage :
1471
Lastpage :
1478
Abstract :
Results of irradiation and high field tunnel injection experiments on MOS capacitors are discussed. The midgap voltage shift as a function of dose is caused by hole trapping only. In the case of tunnel injection, the generation of electron-hole pairs by impact ionization requires a much larger electron density and high fields. Thus a model of charge build-up is established which takes into account the hole trapping in neutral oxide states, the subsequent electron trapping in now positively charged states and detrapping of captured electrons. By means of this model, the prediction of the radiation hardness of MOS devices is feasible, provided that the impact ionization coefficient a is known accurately. If this is not the case, the combined techniques of ionizing irradiation and tunnel injection can be utilized to determine ¿ = ¿o exp(-H¿/F) as a function of the electrical field F. Electron capture and detrapping crosssections ¿n and ßn, resp., can be deduced by fitting the model to the experimental results. An F-3 dependency for ¿n and an exp(-Hß/F) dependency for ßn are found. Only a weak dependence on different processing parameters is observed. The proposed model is verified by a sequence of irradiation and injection steps. The generation of oxide charge is accompanied by an increase in interface state density Dit with a distribution, which peaks at about 0.15 eV above midgap, in both experiments. The results indicate that the generation of interface states is proportional to the amount of trapped holes.
Keywords :
Charge carrier processes; Electron traps; Impact ionization; Interface states; Ionizing radiation; MOS capacitors; MOS devices; Predictive models; Radioactive decay; Voltage;
fLanguage :
English
Journal_Title :
Nuclear Science, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9499
Type :
jour
DOI :
10.1109/TNS.1982.4336389
Filename :
4336389
Link To Document :
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