The effects of thermal stress on the electrical characteristics of metal-oxide-semiconductor diodes with oxides in an ultrathin regime were studied. By centering a quartz ring as a heat sink beneath the silicon wafer, the introduced temperature gradient results in a corresponding hat-like shape thickness distribution for an oxide grown on the wafer with a rapid thermal processing system. The enhanced exterior tensile and compressive thermal stresses due to introduced temperature gradient make the oxides exhibit less and more substrate injection saturation current J sat , respectively, in comparison to control oxides. Their flatband voltage V FB data also clearly show the dependency of effective charge number density N eff on exterior thermal stress. A stress distribution model is proposed to explain the observation. Co-60 irradiation was also performed on the stressed samples to observe this stress extent by examining the variation of electrical characteristics. It was found that an oxide grown on a wafer in exterior compression exhibited better radiation hardness than one in tension.
A methodology to improve the temperature uniformity for the wafer in a rapid thermal processing (RTP) system is presented in this paper. Our work aims at the temperature compensation at the wafer surface by thermal convection. From simulation results of the flow field, it is seen that the cold gas, while flowing from the periphery of the wafer toward the wafer center, causes a lower pressure at and around the center. This lower pressure is due to the flow away gas by the buoyancy and it aggregates thermal nonuniformity. A technique is suggested that consists of suppressing the upward gas flow using a transparent quartz cap above the monitored wafer. Simulation and experimental results show that by implementing this technique, the temperature uniformity of the wafer is improved.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.