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A well-controlled low-temperature process, demonstrated from 350°C to 500°C, has been developed for epitaxially growing elevated contacts and near-ideal diode junctions of Al-doped Si in contact windows to the Si substrate. A physical-vapor-deposited (PVD) amorphous silicon layer is converted to monocrystalline silicon selectively in the contact windows by using a PVD aluminum layer as a transport medium. This is a solid-phase-epitaxy (SPE) process by which the grown Si is Al-doped to at least 1018 cm-3. Contact resistivity below 10-7 Ω·cm2 is achieved to both p- and p+ bulk-silicon regions. The elevated contacts have also been employed to fabricate p+-n diodes and p+-n-p bipolar transistors, the electrical characterization of which indicates a practically defect-free epitaxy at the interface.
Date of Publication: May 2006