Effect of oxide resistance on the characterization of interface trap density in MOS structures

The oxide resistance in a practical MOS capacitor is generally not high enough to be negligible in the evaluation of interface trap density based on the qruasi-static capacitance-voltage (C–V) curve. The importance of the effects of oxide resistance ranging from 10¹³ to 10¹⁶ Ω on the C–V curve and the corresponding interface trap density is theoretically shown. To obtain the oxide resistance in MOS structures the newly reported charge-then-decay method is suggested. From the oxide resistance found, one can compare the distribution curves of interface trap density before and after removing the oxide resistance effect. It is found that the results obtained after removing the oxide resistance effect are more consistent than those without removing it. It addition, the removal of the oxide resistance effect for a sample having a hysteresis C–V behavior is also discussed.