Planarization processes and applications - I. Undoped GeO2-SiO2 glasses

The reflow behavior of undoped GeO2-SiO2 glass films deposited by plasma en hanced chemical vapor deposition using germane, silane, and oxygen has been studied in several annealing ambient atmospheres. Such films offer the pot ential for both trench etch-refill and interlevel dielectric applications. Film synthesis was carried out at 200 degrees C using a dual coil inductive ly coupled plasma system. Oxide film composition was determined using energ y dispersive X-ray spectroscopy and Auger energy spectroscopy. dress-sectio nal scanning electron microscopy has been employed to study the now behavio r of GeO2-SiO2 glass films of varying compositions over silicon trenches. R eflow was studied over the temperature range from 600 to 1050 degrees C. Th e lowest temperature at which complete planarization was observed was 750 a nd 850 degrees C in steam and inert gas ambient atmospheres, respectively, fur films containing approximately 85 mol % GeO2. Surprisingly, it was disc overed that the steam anneals caused a decrease in the Ge composition of as -deposited germanosilicate glasses. This offers the potential for establish ing a reflow hierarchy, which may have application in the planarization of interlevel dielectrics for ultralarge scale integrated circuits. (C) 1999 T he Electrochemical Society. S0013-4651(99)04-035-5. All rights reserved.