THERMAL-REACTIONS OF FLUOROCARBON AND HYDROFLUOROCARBON SPECIES ON SI(100)-(2X1)-CF3I, CF3CH2I, AND C2F4

The thermal reactions of CF3I, CF3CH2I, and C2F4are studied by temperature-programmed reaction/ desorption (TPR/D) on a Si(100) surface. CF3I, CF3CH2I dissociate on the surface, whereas C2F4adsorbs reversibly, without dissociation. Dissociation of the iodine-containing molecules is probably initiated by the cleavage of the relatively weak C-I bonds. In the case of CF3I, the C-I bond dissociation generates 1(a) and CF3(a). 1(a) desorbs as atomic I. CF3(a) dissociates in sequence, producing gas phase SiF2and SiF4and a carbon deposit on the surface. In the case of CF3CH2I, the C-I bond dissociation generates 1(a) and CF3CH2(a). CF3CH2(a) undergoes (3-F elimination to form gas phase CF2CH2as well as further decomposition on the surface. At higher temperatures H2, I, HI, and SiF2desorb and carbon deposits on the surface. © 1995, American Vacuum Society. All rights reserved.