Thermochemical Stabilities of Cluster Ions SiX3 +(SiX4)1,2 (X = H, F and Cl) and SiCl4 +(SiCl4)1,2 Studied by Pulsed-Electron Beam Mass Spectrometry.

An investigation on the ion/molecule reactions in SiCl4 provides critical insights into the plasma chemistry of silicon-based materials. In this study, ion/molecule reactions in a gas mixture of SiCl4/N2 were investigated using a pulsed-electron beam mass spectrometer. The primary reaction products from the reactions of N2 + and N4 + with SiCl4 were found to be SiCl3 + and SiCl4 +, respectively. The thermochemical stabilities of SiCl3 +(SiCl4)1,2, SiCl3 +(N2), and SiCl4 +(SiCl4)1,2 were determined. The discontinuous decrease in the bond energies of SiCl3 +(SiCl4) n and SiCl4 +(SiCl4) n between n = 1 and 2 indicates the participation of a covalent bond (i.e., charge transfer) in SiCl3 +(SiCl4) and SiCl4 +(SiCl4). In contrast, the bond in SiCl3 +(N2) was found to be mainly electrostatic.