Solid-phase epitaxial growth of Si mesas from Al metallization

Si epitaxial growth from solution in solid Al onto crystal Si substrates was studied by scanning electron microscopy. Growth in reentrant corners of the substrate was found to be favored over growth onto a flat surface. For this reason, the smaller-diameter oxide cuts used in integrated-circuit fabrication, in which no portion of the exposed substrate Si is far from a reentrant corner, are favored sites for growth. Si growth readily fills in such oxide cuts forming mesa structures potentially useful in device construction. The probable cause for such preferential growth was indicated in pressure experiments which show that regions in the solid Al under relatively less compression are favored locations for growth.