9803177 Weaver The proposed program aims to investigate the interactions of fluorine with silicon surfaces, the modifications that are brought about by etching, and the atomic-scale interactions that underlie material removal. The fluorine-silicon (100) system is an ideal model system because problems can be addressed that are of broad importance, namely how ideal surfaces develop "corrosive layers" when exposed to reactants and how multilayer etching competes with layer-by- layer etching. Atomic-resolution scanning tunneling microscopy would be used to investigate fluorine chemisorption and fluorine-fluorine repulsive interactions in the adlayer. Studies have been designed that would determine the atomic sequency of events leading to silicon difloride desorption and the implications vis-a-vis layer-by- layer etching with silicon defluoride. Others would focus on corrosive-layer silicon tetrafluoride eteching, the nucleation of fluorosilyl structures on the surface, and the strucural consequences of material removal from these disordered layers. %%% These studies of fluorine etching of silicon are pertinent to modern technologies based on silicon and other semiconductors. In the $700b microelectronics industry, for example, the majority of the 1018 transistors produced in 1997 were carved into monolithic pieces of silicon using themethods of chemical etching. The shapes, positions, and registry of these structures are controlled with sub-micron accuracy. This project focuses on the underlying chemical and physical processes responsible for this etching. Deeper insights are needed to achieve dfurther miniaturization for tomorrow's circuitry. ***
