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Laterally nonuniform distributions of radiation-induced oxide charge and interface traps near MOSFET junctions have been found in a variety of samples, and such nonuniformities could significantly affect the transistor's transconductance, channel resistance, and effective channel length. The degree of nonuniformity depends strongly on the process technology, as revealed by three independent measurement techniques. Device simulation results have confirmed the impact of such edge effects on transistor parameters.

A charge-pumping-based approach for characterizing the embedded oxide charges andthe spatial distribution of the interface traps bordering the source/drain junctions is reported. Simple to execute, the method facilitates independent measurement of the interface trap and oxide charge constituents. A few examplesare given to demonstrate its utility along with the experimental results and a comparison with other comparable techniques.

Using a rapid charge pumping technique, we found that the mean capture cross-section of interface traps in MOSFETs sharply decreased immediately after irradiation. Further changes of the capture cross-section during subsequent relaxation depended on the gate bias during both irradiation and storage. Radiation dose dependence has also been investigated. Possible mechanisms and correlations between interface-trap density and capture cross-section are discussed.

Enhanced radiation damage near channel edges of n- and p-channel MOS transistors has been observed by the measurements of channel resistance and gate-induced drain leakage (GIDL) current. Good correlation between these two types of measurements has been established. The degree of such edge effects has been found to depend strongly on the process technology. In some cases, the radiation damage near the edges plays a major role in the total device degradation, and it becomes more important as the device size reduces. A comparison has been made among transistors fabricated with standard, fluorinated, and radiation-hardened oxides. The results suggest that it is possible to minimize the radiation-induced edge effects by the use of appropriate process conditions.

Electron trapping occuring in the gate oxide of n-channel metal oxide semiconductors is studied. The mechanism, which is caused by constant-voltage Fowler-Nordheim injection, was analyzed via various measurement techniques and a subdivision of the gate oxide region into three zones. It revealed the presence of stronger charge trapping near the channel edges which lead to a rise in the channel length of up to 0.5 micrometer.