Extended x-ray absorption fine structure analysis of the difference in local structure of tantalum oxide capacitor films produced by various annealing methods
Extended x-ray absorption fine structure (EXAFS) above the Ta L3 edge on tantalum oxide capacitor films has been measured. Tantalum oxide films were prepared by low-pressure chemical vapor deposition (CVD) using a Ta(OC2H5)5 and O2 gas mixture. Four kinds of tantalum oxide films were studied: as-deposited (amorphous), N2 annealed (crystalline), dry O2 annealed (crystalline), and O2-plasma annealed (amorphous). From EXAFS analysis, differences in the local structures of tantalum oxide capacitor films, in terms of oxygen deficiency around Ta, were observed in the various annealed films. The leakage current characteristics of tantalum oxide capacitors correspond to the differences in the local structures around Ta.