SURFACE-CHEMISTRY OF DIETHYLSILANE AND DIETHYLGERMANE ON SI(100) - ANATOMIC LAYER EPITAXY APPROACH

The surface chemistry of diethylsilane (DES) and diethylgermane (DEG) on the Si(100) surface was studied using high-resolution electron-ener gy-loss spectroscopy and temperature programmed desorption. High-resol ution electron-energy-loss spectra indicate that the precursors chemis orbed dissociatively as (C2H5)2MHx(ad) and (2-x)H(ad) [x = 0,1; M = Si or Ge] groups at room temperature and that the ethyl groups remain bo nded to the precursor Si or Ge. Thermal annealing of DEG covered surfa ces indicated that the ethyl groups remain attached to Ge at least up to the desorption temperature. Ethyl ligands react to form ethylene vi a a beta-hydride elimination pathway. The ethylene desorption peak tem perature from DEG dosed surfaces was approximately 40 K lower than tha t from DES dosed surfaces (733 K). We propose that ethylene desorbs fr om Ge atoms rather than from Si surface atoms. The hydrogen remaining on the surface after ethylene desorption desorbs from the beta1 state, with peak maxima at 810 and 780 K for DES/Si(100) and DEG/Si(100), re spectively.