Abstract
Modulated beam mass spectrometry has been used to investigate the etch products, surface chemistry and product desorption mechanisms for interaction of Cl2 with Cu(100). The dominant etch product is Cu3Cl3 for T —580 °c and CuCl for T650°c. Exposure of Cu(100) to Cl2 at temperatures below 150 °C leads to the growth of a copper chloride layer whose thickness increases linearly with time for exposures greater than approximately 1000 langmuirs. The rate of growth of the chloride layer decreases with increasing temperature. Temperature programmed desorption experiments indicate that the chloride desorbs as Cu3Cl3 with zero order kinetics and an activation energy for desorption of about 33 kcal/mol. The zero order desorption kinetics suggest that the quantity of chlorine on the immediate surface remains constant until the chlorine in the bulk is depleted. The activation energy for desorption of 3 3 kcal/mol is within experimental error equal to the heat of sublimation of Cu3Cl3 from pure copper chloride. This result suggests that etching is simply a “compound growth”-evaporation reaction. Ion bombardment is shown to suppress the etch rate which is probably a consequence of ion-induced dissociation of Cu3Cl3 and possibly a decreased concentration of chlorine in the surface region. © 1985, American Vacuum Society. All rights reserved.