Selective epitaxial growth condition in the disilane gas source silicon molecular beam epitaxy was studied as functions of the substrate temperature and the growth rate. At lower substrate temperature or at lower silicon growth rate, perfect selectivity was attained. The selectivity dependence on the temperature and that on the growth rate indicate that the control of the disilane molecule’s dissociation on the SiO2 surface is important for selective growth.

Si/SiO2 interface structures in laser-recrystallized Si on SiO2 were studied with a high-resolution transmission electron microscope. The (001) Si/SiO2 interface with (001) Si substrate as a seed was excellent in flatness, flatter than that of the initial interface before recrystallization. However, the (11̄5) Si/SiO2 interface with (11̄5) Si substrate was saw-toothed with {100}T and {111}T microfacets. After twin boundary generation, the interface was changed to {110}T or {111}T and was flattened considerably. A Si/SiO2 interface reaction occurred during laser recrystallization. Since low-index Si planes are thought to have low interface energies with SiO2 at their interface, atomically flat or saw-toothed interfaces appeared as a result of this interface reaction. Moreover, twin boundaries, rather than saw-toothed interfaces, might have been generated for the reduction of the interface energy.

No abstract

The dependence of the proximity effect, which deforms electron-beam exposed patterns, on the substrate material has been investigated theoretically and experimentally. Substrates examined are Si, SiO2, Cr, Mo, Au and their double layers, which are used in LSI fabrication process with a direct writing technique. The proximity effect is approximated as the sum of absorbed energy distributions in a resist layer, which are calculated separately with respect to electron re-incidence number (Ns) from substrate into resist. A Monte Carlo simulation for electron scattering trajectories was used to obtain the spatial distributions of absorbed energy in a resist. The incident beam extent influence was examined. A new evaluation technique was used to obtain the exposed intensity distributions. The absorbed energy distributions, constituting the modeled proximity effect, are in good agreement with experimental results. The absorbed energy distribution for Ns=0 with a Gaussian incident beam is approximated by the function Coexp(−r/σ0). The distribution for Ns?1, expected in the case of a high atomic weight substrate, is approximated by the function Csubexp(−r/σsub).

Articles you may be interested inMolecular beam epitaxy growth of metamorphic high electron mobility transistors and metamorphic heterojunction bipolar transistors on Ge and Ge-on-insulator/Si substrates J.Lowtemperature CV characteristics of Sidoped Al0.3Ga0.7As and normal nGaAs/NAl0.3Ga0.7As isotype heterojunctions grown via molecular beam epitaxy