Hot carrier and radiation effects in metal-oxide-semiconductor devices

Effects of hot-carrier and ionizing radiation on MOS (Metal-Oxide-Semiconductor) interfaces are the foci of this thesis work. The primary objective of this work is to achieve a better understanding of these two different but closely related damage mechanisms and their effects on device operation.; A newly developed modified charge pumping technique that allows direct measurement of localized oxide charge is particularly useful for channel hot-carrier (CHC) damage studies. Many important aspects of CHC-induced damage, including oxide charge build-up, its various dependencies, and the effects of alternating stressing, have been studied. The new charge pumping technique can also be extended for measurements of lateral distributions of localized interface trap and oxide charge density. It is found that the lateral distribution of the CHC-induced damage roughly follows the electric field profile during stressing. This technique also helps us understand the nonuniformity of radiation-induced damage in MOS field-effect transistors (MOSFET's).; A single frequency AC conductance technique, which is a significant improvement over the conventional technique, has been developed and used to study the time evolution of interface-trap capture cross sections during the interfacial defect transformation process which was recently discovered in the Yale laboratory. A new implementation of the charge pumping technique, which can be used for rapid determination of interface-trap parameters, has also been used to study the time evolution of interface-trap capture cross sections in MOSFET's. Both studies show similar results: the interface-trap capture cross sections decrease significantly after x-ray or hot-carrier induced damage, and gradually recover with time towards their pre-damage values. The time scale of such recovery is consistent with that of the defect transformation process.; Surface generation and recombination through interface traps have been studied with the emphasis on the respective cross sections. An equivalence between the generation and recombination cross sections has been established experimentally. One surprising but very important finding is that the capture cross sections measured by the charge pumping technique are very different from those obtained by the recombination current measurement. Physical explanations are given to account for the differences and similarities between the various capture cross sections as revealed by these different techniques.