Deposition and characterization of undoped and boron and phosphorus doped (SixGe1-xO2) glass films

Glass films of undoped and boron and phosphorus doped GeO2-SiO2 glass films were prepared by plasma enhanced chemical vapor deposition using germane, silane, phosphine, diborane, and oxygen as precursor gas sources with argon as a carrier gas. Film syn thesis was carried our at 200 degrees C using a dual-coil, inductively coupled plasma system. The presence of silane was n ot necessary to catalyze the decomposition of germane in the plasma environ ment as required in a strictly thermal environment. The index of refraction of undoped films changes linearly with SiO2 composition, and deposition ra te was nearly constant across all nlm compositions. Oxide film composition was determined using energy dispersive X-ray spectroscopy and Auger energy spectroscopy. For undoped films, solid-phase SiO2 composition varied linear ly with silane gas-phase composition. For doped compositions, phosphorus mo le fraction in the solid phase was up to a factor of two greater than that present in the gas phase. In contrast to this, the quantity of boron incorp orated into the solid phase was a factor of five to six less than present i n the gas phase. When both dopants were present in the gas phase, the amoun t of each incorporated into the solid phase was similar to that in the gas phase. (C) 2000 The Electrochemical Society. S0013-3651 (99)07-047-0. All r ights reserved.