Metal Organic Chemical Vapor Deposition Characteristics of Germanium Precursors

Abstract

Polycrystalline germanium (Ge) thin films were grown by metal organic chemical vapor deposition (MOCVD) using tetra-allyl germanium [<TEX>$Ge(allyl)_4$</TEX>], and germane (<TEX>$GeH_4$</TEX>) as precursors. Ge thin films were grown on a <TEX>$TiN(50nm)/SiO_2/Si$</TEX> substrate by varying the growth conditions of the reactive gas (<TEX>$H_2$</TEX>), temperature (<TEX>$300-700^{\circ}C$</TEX>) and pressure (1-760Torr). <TEX>$H_2$</TEX> gas helps to remove carbon from Ge film for a <TEX>$Ge(allyl)_4$</TEX> precursor but not for a <TEX>$GeH_4$</TEX> precursor. <TEX>$Ge(allyl)_4$</TEX> exhibits island growth (VW mode) characteristics under conditions of 760Torr at <TEX>$400-700^{\circ}C$</TEX>, whereas <TEX>$GeH_4$</TEX> shows a layer growth pattern (FM mode) under conditions of 5Torr at <TEX>$400-700^{\circ}C$</TEX>. The activation energies of the two precursors under optimized deposition conditions were 13.4 KJ/mol and 31.0 KJ/mol, respectively.