A novel subthreshold slope technique for the extraction of the buried-oxide interface trap density in the fully depleted SOI MOSFET

A novel experimental technique, based on the double-gate operation, is proposed for extracting the back interface trap density of the fully depleted SOI MOSFET. The method relies on simple current-voltage measurements, requires no prior knowledge of the silicon film thickness, and successfully eliminates inaccuracies arising from thickness variations of the accumulation layer, by maintaining both interfaces in depletion. The sensitivity of the technique is shown to depend on the ratio of the interface trap and oxide capacitances of the buried oxide, and is thus limited only by the buried oxide thickness. The technique has been successfully used to monitor the increase in back interface trap density following Fowler-Nordheim stress.