The reactive ion etching (RIE) of silicon in CF2Cl2 plasma was considered. A different kinetics of the etching process at energies of bombarding ions 100 and 400 eV were observed. The compositions of polymeric layers were measured by X-ray photoelectron spectroscopy (XPS) to explain the kinetics of the etching. Significant variations of the composition of polymeric layers were observed. The variations of concentrations of free and reacted carbon and alternation of bond types on the surface influence the etching rate. XPS measurements showed that C-CF and CF-M species form a Teflon-like polymer in later stages of etching process. The polymer formed suppresses the etching process at low ion energy. Energy of bombarding ions of 400 eV is sufficient to destroy partially the polymer and produce etching. A theoretical model was proposed to explain the kinetics of composition of polymeric layers. (C) 2002 Elsevier Science B.V. All rights reserved.