Considerations for further scaling of metal–insulator–metal DRAM capacitors

Abstract

Effective electron tunneling mass mtunnel is extracted from trap-assisted leakage in Sr-rich strontium titanate and rutile titanium oxide films in metal–insulator–metal (MIM) capacitors and compared with theoretical values obtained from first principles calculations of the imaginary band structure. Optimum orientations of films and stoichiometry impacting mtunnel are also discussed. Because future vertical DRAM integration schemes also stipulate maximum thickness of the MIM capacitor, mtunnel is shown to be a critical parameter influencing intrinsic leakage and potentially limiting further scaling.