Ultra-thin ZrO2/SrO/ZrO2 insulating stacks for future dynamic random access memory capacitor applications

Aiming for improvement of the ZrO 2-based insulator properties as compared to the state-of-the-art ZrO 2/Al 2O 3/ZrO 2 stacks beyond 20 nm dynamic random access memory (DRAM) technology applications, ultra-thin (5 nm) ZrO 2/SrO/ZrO 2 stacks with TiN electrodes deposited by physical vapor deposition are addressed. By replacing the Al 2O 3 interlayer with SrO, the effective dielectric permittivity of the stack can be increased as indicated by electrical analysis. At the same time, no degradation of the insulating properties of the SrO-containing stacks and minor changes in the reliability, compared to an Al 2O 3 interlayer, are found. These results are indicating the possibility of further reducing the effective oxide thickness of the ZrO 2-based stacks to come close to 0.5 nm for future DRAM capacitors.