MBE in MOS technology applied to speed increases in VHSICS

Silicon molecular beam epitaxy (MBE) was used to grow submicron undoped epitaxial Si layers on 2 inch Si substrates. The films had low defect densities. Radiative wafer heating was used, and no temperatures above 900 C were necessary. In addition, the single crystal silicon suboxides Si2O and Si2O3 were grown by MBE for the first time on (111) and (100) Si substrates, with Si2O growing primarily on the (111) wafers. Undoped Si films were characterized for defects with a Wright etch, and for doping and thickness with spreading resistance. The single crystal suboxides were identified by interpreting reflection electron diffraction (RED) patterns and by comparing Auger spectra with published data for amorphous SIPOS (semi-insulating polysilicon) films containing the same compounds. Capacitance-voltage results show MOS-type behavior, although with charge injection and some conductivity of the suboxide. The Si2O crystalline structure on (111) Si may be thought of as oxygen planes between double (111) planes of Si, with a 180 deg Si-O-Si bond. Crystalline Si2O3 is an assembly in a Si-like lattice of Si4O6 molecules, each of which has one tetrahedral bond per silicon atom. All other Si bonds are satisfied by 109.5 deg Si-O-Si bonds.