Discrepancies between charge-pumping, dual-transistor, and midgap measurements of D(sub it)

摘要

Several different techniques are used to electrically characterize defects at or near the Si/SiO(sub 2) interface. Three common methods are the charge-pumping, midgap, and dual-transistor techniques. Each of these techniques offer advantages and disadvantages compared to the others. For instance, charge-pumping measurements are not significantly affected by charge lateral non-uniformities and can provide high-sensitivity measurements of the average density of interface traps. However, charge-pumping measurements cannot provide accurate measurements of the number of charged oxide traps. In contrast both the dual-tranistor and midgap techniques can provide good estimates for threshold-voltage shifts due to oxide traps and interface traps, but these estimates can break down when significant charge lateral non-uniformities are present in the oxide. Considering the widespread use of these, techniques, it is of practical and theoretical importance to quantitatively compare them. At the SISC, we will present a detailed comparison of the charge-pumping, midgap, and dual-transistor techniques. Values for the density of interface traps measured using the three techniques will be compared for n- and P-channel transistors fabricated using several different process technologies, and under different process technologies, and under different irradiation and anneal conditions. Discrepancies between the different techniques are observed. Causes for the discrepancies will be explored at the SISC.