Microwave Irradiation Effect on Ti-Doped Ta2O5 Stacked Capacitors

The effect of short time (up to 15 s) microwave irradiation at room temperature on the electrical characteristics of Ti-doped Ta2O5 (8-30 nm) stacks with Al and W gates has been investigated. The irradiation has major impact on the leakage current and can strongly reduce it up to 4 orders of magnitude (current level below ~ 10-7 A/cm2 is easily obtained). The current reduction and a tendency of conduction mechanism changing upon irradiation is considered to be due to irradiation induced annealing of electrically active defects generated during Ta2O5 deposition, during doping and/or by a high damage gate deposition process as rf sputtering. The results are compared with those for pure Ta2O5 and are discussed in terms of relative influence of the initial parameters of the stack, and the role of incorporated Ti on the oxygen-vacancy related defects. The current reduction is not accompanied by either interface layer thickness increase or film crystallization. As easily applicable method microwave irradiation can be used as alternative to high temperature annealing process for leakage current characteristics improving of high-k Ti-doped Ta2O5 capacitors. The review covers important Patents which are useful in this field.