Temperature dependence of chemical-vapor deposition of pure boron layers from diborane

Surface reaction mechanisms are investigated to determine the activation energies of pure boron (PureB) layer deposition at temperatures from 350?°C to 850?°C when using chemical-vapor deposition from diborane in a commercial Si/SiGe epitaxial reactor with either hydrogen or nitrogen as carrier gas. Three distinguishable regions are identified to be related to the dominance of specific chemical reaction mechanisms. Activation energies in H2 are found to be 28?kcal/mol below 400?°C and 6.5?kcal/mol from 400?°C to 700?°C. In N2, the value decreases to 2.1?kcal/mol for all temperatures below 700?°C. The rate of hydrogen desorption is decisive for this behavior.