CHLORINE INCORPORATION IN HCL OXIDES

As much as 1016 Cl/cm2 has been incorporated into SiO2 thin films by thermal oxidation of Si in mixture of O2 and HCI gases. The chlorine concentration and location in the oxide film were determined by Rutherford back-scattering of a particles. The oxide preparation conditions included the growth temperature range from 1150° to 1300 C, the growth time range of 15-60 min, and gas phase HCI/O2 concentrations in the range of 0-10 volume percent (v/o). The total chlorine concentration in the oxide film increased monotonically with the HCI content of the growth ambient. The increase was linear at first, rose abruptly over a limited range of HCl/02 concentration (above the so-called “threshold”), and then again increased linearly at higher HCI/O2 concentrations. The threshold moved to lower HCI/O2 concentrations as either growth time or growth temperature was increased. The CI concentration in the oxide film increased monotonically with growth time and growth temperature. For all growth conditions investigated, chlorine was found to be concentrated at or near the Si/SiO2 interface. Direct scanning electron microscopy and replication studies indicated that the oxide surface was uneven for oxides grown in HCI/O2 concentrations above threshold. The size of the surface features increased at higher HCl/O2 concentrations. This lateral nonuniformity did not appear in samples prepared in HCI/O2 concentrations below threshold. © 1979, The Electrochemical Society, Inc. All rights reserved.