Growth Mechanism for Germanium Deposition near a SiO[sub 2]-Ge Boundary

Enhanced growth (ridge growth) of germanium on germanium near an oxide‐germanium boundary has been studied in the Ge ‒ H ‒ Cl system as a function of temperature and oxide pad width. A model is presented assuming that surface diffusion of some germanium‐containing species occurs along the SiO 2 pads, thereby feeding additional material to the germanium at the pad edge to form the ridge. It is shown that volume diffusion effects alone cannot explain the data. It appears that the reaction at the oxide‐germanium boundary is much faster than surface diffusion and that adsorption of germanium‐bearing species on the oxide mask constitutes a rate‐limiting step.