HYDROGEN DESORPTION FROM SI - HOW DOES THIS RELATE TO FILM GROWTH

The desorption of hydrogen from the Si(100) surface is investigated. The hydrogen coverage is generated by the adsorption of atomic hydrogen, by the thermal decomposition of disilane, or during silicon epitaxy using silane in a rapid thermal chemical vapor deposition reactor. Temperature programmed desorption studies are then used to help yield information about the hydrogen surface coverage and the desorption kinetics of hydrogen. The desorption order of hydrogen is first order, consistent with previously reported single crystal studies. However, the activation energy for desorption of hydrogen from surfaces generated during Si epitaxy with SiH4 is considerably different. The activation energy for hydrogen desorption from these epitaxially grown layers is 49+/-3 kcal/mol. The presence of monatomic steps on the surface, which are created during the temperature quench, is believed to play a role in this difference of activation energies. Single crystal, ultra-high vacuum based studies using atomic hydrogen and disilane adsorption and desorption are used to gain further insight into this phenomena. (C) 1995 American Vacuum Society.