Fabrication of semiconductor stacks with ruthenium-based materials

Abstract

This disclosure provides a method of fabricating a semiconductor stack and associated device such as a capacitor and DRAM cell. In particular, a bottom electrode upon which a dielectric layer is to be grown may have a ruthenium-based surface. Lattice matching of the ruthenium surface with the dielectric layer (e.g., titanium oxide, strontium titanate or barium strontium titanate) helps promote the growth of rutile-phase titanium oxide, thereby leading to higher dielectric constant and lower effective oxide thickness. The ruthenium-based material also provides a high work function material, leading to lower leakage. To mitigate nucleation delay associated with the use of ruthenium, an adherence or glue layer based in titanium may be employed. A pretreatment process may be further employed so as to increase effective capacitor plate area, and thus promote even further improvements in dielectric constant and effective oxide thickness ('EOT').