Silicon oxide films formed using two different chemical vapor deposition (CVD) techniques have been characterized by selected etching properties, both in dry (plasma) etching and in wet (chemical) etching. Dry etching was accomplished using CHF3+O2in a reactive ion etching (RIE) system. The films investigated are undoped silicon oxide, phosphorus‐doped silicon oxide at 4 mol % P2O5, and phosphorus‐doped silicon oxide at 9.5 mol % P2O5. The effects of densification, i.e., thermal treatments carried out at 900 °C in an inert atmosphere (N2) and at 920 °C in steam, are discussed in detail. A decrease in etch rate is observed and considered to be an indication of the structural changes that lead to less porous and more stable films.