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 degrees C to 850 degrees 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 H-2 are found to be 28 kcal/mol below 400 degrees C and 6.5 kcal/mol from 400 degrees C to 700 degrees C. In N-2, the value decreases to 2.1 kcal/mol for all temperatures below 700 degrees C. The rate of hydrogen desorption is decisive for this behavior. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4752109]