Correlation between Electrical and Optical Properties of Tantalum Anodic Oxide and Electron Cyclotron Resonance Etching Studies of E-beam Deposited Ta 2 O 5 Films

The anodic tantalum oxide films were grown in 5ml/98% H 2 SO 4 electrolyte saturated with additional H 2 . Discharge currents were collected immediately after growth. The optical properties of these films were studied with an ellipsometer over a wide range of frequencies from the UV to the IR. It was established that films for which the discharge currents followed the known "~ -1" power dependence (specific for films that can sustain large electric fields in the MV/cm range) have different optical properties as compared to films for which the discharge current is not represented by that empirical function. Etching studies of e-beam deposited Ta 2 O 5 films, combined with reflectance measurements after each etch step, resulted in a shift in the reflectance spectrum as a function of film thickness. This empirical f versus d dependence (where f is the frequency corresponding to the reflectance minimum for each film thickness, d) was used to calculate the energies of the 4d doublet of Ta +5 in Ta 2 O 5 . Ta 2 O 5 has been studied for rather a long time (see for example The reflectance data gathered after the dry etch steps resulted in the experimental curves (reflectance versus Ȝ), which allowed us to obtain an empirical function of f versus d shown i