Sub-500 degrees C solid-phase epitaxy of ultra-abrupt P+-silicon elevated contacts and diodes

Abstract

A well-controlled low-temperature process, demonstrated from 350/spl deg/C to 500/spl deg/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 10/sup 18/ cm/sup -3/. Contact resistivity below 10/sup -7/ /spl Omega//spl middot/cm/sup 2/ is achieved to both p/sup -/ and p/sup +/ bulk-silicon regions. The elevated contacts have also been employed to fabricate p/sup +/-n diodes and p/sup +/-n-p bipolar transistors, the electrical characterization of which indicates a practically defect-free epitaxy at the interface.