Plasma enhanced chemical vapor deposition of boron and phosphorus doped mixed glass films in a horizontal tube reactor using germane , silane , diborane , phosphine , and oxygen has been studied. The glass films offer the potential for both trench refilling and interlevel dielectric applications. Film synthesis was carried out at 200°C using a dual coil inductively coupled plasma system. Oxide film composition was determined using energy dispersive X‐ray spectroscopy and Auger energy spectroscopy. Cross‐sectional scanning electron microscopy was employed for studing the compositional dependency of the reflow behavior of the mixed , , , and glass films over silicon trenches under various ambient atmospheres. Reflow experiments were performed at temperatures ranging from 550 to 800°C in various gas ambient atmospheres. As result of the work, a low temperature (∼600°C) reflow process was developed resulting in fully planar dielectric films. This process may have application for planarization of interlevel dielectrics for ultralarge scale integrated circuits. © 1999 The Electrochemical Society. All rights reserved.