Effect of microwave radiation on the properties of Ta2O5-Si microstructures

The paper presents results of the effect of microwave irradiation at room temperature on the properties of thin layers of tantalum pentoxide deposited on Si by rf sputtering. Electrical characterization is performed in conjunction with Auger electron spectroscopy and atomic force microscopy. Among exposure times used (1; 5; 10 s), treatment of about 5 s shows the best promise as an annealing step--an improvement of number of parameters of the system Ta2O5-Si is established (dielectric constant and surface morphology; stoichiometry and microstructure of both the bulk oxide and the interfacial transition region; electrical characteristics in terms of oxide charge density, leakage current and breakdown fields). At the same time the microwave irradiation is not accompanied by crystalization effects in Ta2O5 and/or additional oxidation of Si substrate. It is concluded that the short-time microwave irradiation can be used as an annealing process for Ta2O5-Si microstructures and it has a potential to replace the high-temperature annealing processes for high-k insulators.