Silicon films on sapphire

Abstract

The physical properties of silicon on sapphire (SOS) thin films and their impact on the operation of integrated devices are systematically reviewed. The preparation of the SOS material is described from the fabrication of the sapphire substrate and the silicon film heteroepitaxy up to the .recently proposed regrowth techniques. The microscopic properties and the relevant methods used for inspection are discussed with emphasis on autodoping, stress, lattice defects and interface behaviour. Following the presentation of average transport and recombination parameters, deduced from measurements involving the contribution of the whole film, the non-homogeneity of the S O S film along the epitaxial direction will be outlined. The electrical properties of the silicon-sapphire interface and of the interfacial transition layer are compared to those of the front Si-SiO, interface. Attempts are made to correlate the data derived by various characterisation techniques in order to reveal a coherent image of the Si film volume sandwiched by two very dissimilar interfaces. Finally, the processing and the performance of SOS devices are discussed and favourably compared to the case of bulk Si technology.

Deep-amorphization and solid-phase epitaxial regrowth processes for hybrid orientation technologies in SOI MOSFETs with thin body

“…For DA of (1 1 0) SOI layers, Si ions were implanted at high dose (61 Â 10 15 cm À2 ) and energy of 80-110 keV. SPER is a well known mechanism, currently used for SOS structures [8]. The optimum annealing temperature was found to be 900°C by investigating the recovery of the electrical characteristics with Pseudo-MOSFET measurements as a function of the annealing temperature.…”

Silicon-on-insulator: materials aspects and applications

“…Because of their composition and transparency, sapphire substrates are not compatible with standard silicon processing. Reviews on SOS technology can be found in [1,6,7] and references therein. Al 2 O 3 single crystals (sapphire) are rhombohedral; for (100) silicon hetero-epitaxy, the (11 -02) orientation has proved most useful [6].…”

“…Reviews on SOS technology can be found in [1,6,7] and references therein. Al 2 O 3 single crystals (sapphire) are rhombohedral; for (100) silicon hetero-epitaxy, the (11 -02) orientation has proved most useful [6]. The silicon layer is grown through pyrolysis of silane (SiH 4 ); deposition temperatures around 900±10008C are chosen to minimise defects in silicon and simultaneously reduce the risk of autodoping with aluminium.…”

LOW THIRD-ORDER INTERMODULATION DISTORTION IN Ba_0.6Sr_0.4TiO₃ THIN FILM INTERDIGITAL CAPACITORS

“…This offers lower power dissipation, higher operating speed and minimum parasitic semiconductor junctions due to the highly insulating sapphire substrate. This technology uses a very thin layer of silicon deposited on an r-plane sapphire substrate, which provides a suitable orientation for the growth of silicon [3]. By depositing the BST film early in the SoS process, the high deposition temperature can be tolerated without affecting the silicon epilayer [4].…”