The Oxidation of Sputtered Tantalum Films and Its Relationship to the Stability of the Electrical Resistance of These Films

A study of the oxidation of sputtered tantalum films was carried out to help explain the changes in electrical resistance of such films when heated in air at 100°C. A microbalance was used to obtain the oxidation data over a range of temperatures from 100-600°C in pure oxygen at a pressure of 7.6 cm of Hg. The electrical resistance of films was measured over a temperature range up to 200°C. Some results were also obtained when heating was carried out in a vacuum of 10^--6mm of Hg. From a consideration of the oxidation data and the electrical resistance data, it appears that oxidative effects based on a simple model of oxide film formation do not play a major role in affecting the stability of the electrical resistance of the films under the test conditions. Oxidative effects at grain boundaries may have more of an influence. However, structural changes, not yet characterized, may be equally important in accounting for the resistance changes.