The chemical etching of silicon in Br-2 ambient is considered. The desorption activation energy for an SiBr2 molecule is evaluated using experimentally measured dependences of etching rates on concentration of Br-2 molecules. It is found that the desorption activation energy of SiBr2 molecules is equal to E-d = (1.52 +/- 0.18) eV. Desorption of SiBr2 molecules is an etching-rate limiting process at high concentration of Br-2 in the gas phase. (C) 2011 Elsevier B.V. All rights reserved.