CHEMICAL-STRUCTURE AND REACTIVITY OF A SILICON SINGLE-CRYSTAL SURFACEFLUORINATED BY XENON FLUORIDE

A reconstructed Si single crystal surface was fluorinated using xenon fluoride. All dangling bonds on the 2 X 1 reconstructed surface of Si( 100) were terminated by fluorine atoms, and Si-F bonds were generated. However, dimer bonds remained after the treatment. This is different from the situation where dimer bonds are easily terminated by hydrogen atoms in a hydrogenation treatment. A bulky Si-F group is considered to sterically hinder fluorine termination of a dimer bond. Also, only an adatom bond seems to be terminated by a fluorine atom in the fluori nation treatment of a Si(Ill) 7 X 7 reconstructed surface. When the fl uorinated Si(100) surface was exposed to the atmosphere, dimer bonds w ere observed to be oxidized immediately. Also following the reaction, the backbond of the Si-F group is oxidized and the S-F bond itself was hydrolyzed. The fluorinated surface, which is chemically active, diff ers from the hydrogen-passivated surface.