<title>Characterization of microstructure of Si films grown by laser-enhanced photo-CVD using Si<formula><inf><roman>2</roman></inf></formula>H<formula><inf><roman>6</roman></inf></formula></title>

Abstract

Defect characterization of epitaxial silicon films grown on lightly boron-doped Si (100) substrates by low temperature photo-enhanced chemical vapor deposition (PCVD) using 193 nm ArF excimer laser dissociation of Si2H6 in an ultra-high-vacuum (3 X 10-9 Torr) chamber is discussed. A factorial design of experiments was used to investigate the dependence of crystallinity and growth rate on laser intensity, Si2H6 partial pressure, substrate temperature, and substrate-to-laser-beam distance. PCVD of Si was achieved in two ways: with the laser passing parallel to the substrate or directly incident on it. For parallel laser incidence, epitaxial films were achieved at temperatures as low as 250 degree(s)C with controllable deposition rates of 0.5 approximately equals 4 angstroms/min. using photon flux densities of 1015 photons/pulse.cm2, and Si2H6 partial pressure of 20 mTorr. The growth rates were observed to be linearly dependent on laser power. For direct laser incidence, single crystal films with a growth rate of approximately equals 20 angstroms/min. were obtained at a photon flux density of 7 X 1014 photons/pulse.cm2 at 300 degree(s)C and 20 mTorr Si2H6 partial pressure. The growth rate were found to be linearly dependent on photon flux density also. The crystallinity was studied by in situ reflection high energy electron diffraction (RHEED), and selected area electron diffraction in a transmission electron microscope (TEM), and defects such as stacking faults and dislocation loops were investigated by TEM and dilute Schimmel etching/Nomarski microscopy.