The reflow behavior of undoped GeO2-SiO2 glass films deposited by plasma enhanced chemical vapor deposition using germane, silane, and oxygen has been studied in several annealing ambient atmospheres. Such films offer the potential for both trench etch-refill and interlevel dielectric applications. Film synthesis was carried out at 200 degrees C using a dual coil inductively coupled plasma system. Oxide film composition was determined using energy dispersive X-ray spectroscopy and Auger energy spectroscopy. dress-sectional scanning electron microscopy has been employed to study the now behavior of GeO2-SiO2 glass films of varying compositions over silicon trenches. Reflow was studied over the temperature range from 600 to 1050 degrees C. The lowest temperature at which complete planarization was observed was 750 and 850 degrees C in steam and inert gas ambient atmospheres, respectively, fur films containing approximately 85 mol % GeO2. Surprisingly, it was discovered that the steam anneals caused a decrease in the Ge composition of as-deposited germanosilicate glasses. This offers the potential for establishing a reflow hierarchy, which may have application in the planarization of interlevel dielectrics for ultralarge scale integrated circuits.