New capping technique for zone-melting recrystallization of silicon-on-insulator films

A new capping technique employing high-temperature NH3 annealing has been developed to ensure uniform wetting by the molten Si zone during zone-melting recrystallization of Si-on-insulator films. By using this technique, we have reproducibly prepared 0.5-μm-thick films with 〈100〉 crystalline texture that are greatly improved in smoothness, void density, and thickness uniformity. In addition, recrystallized 1-μm-thick films have been obtained with large areas that are free of subboundaries, containing only threading dislocations at densities of less than 2×106 cm−2.