Tantalum oxide (Ta2O5) thin film capacitors for multichip module (MCM) applications were investigated. Through the capacitor characterization and RBS compositional analysis, it was found that when the sputtering power and Ar flow rate is 200 W and 60 seem, respectively, the stoichiometric Ta2O5 film can be obtained at the O2 gas flow rate of 50 seem. The low temperature annealing (150°C) is useful to increase the capacitor yield, but the annelaing in oxygen atmosphere causes the leakage current to increase. When the Ta-oxide capacitors were fabricated on the polymer-laminated substrate, leakage current increased and breakdown field strength decreased. These are due to the surface roughness effects of the polymer films and also the Al bottom electrode layer. It was demonstrated that the Ta2O5 capacitors fabricated on the Upilex-S polymer film can meet the requirements of integrated capacitors for MCM applications. ？ 1999 Elsevier Science S.A. All rights reserved.