A novel BST storage capacitor node technology using platinum electrodes for Gbit DRAMs

A new stack capacitor structure using barium strontium titanate (BST) has been developed for Gbit scale DRAMs. The feasibility of fabrication of this structure using Pt as the electrode material is demonstrated through the use of novel processes. An appropriately placed oxidation resistant barrier and adhesion layers enhance the thermal and physical stability of the bottom electrode structure. Electrical results, including AC electrical stress reliability measurements, for 3-D storage nodes with side-wall contribution are presented. Fence-free etching of Pt for bottom electrode formation is shown using a new hardmask based process. Successful back-end integration (ILD and metallization) of BST capacitors is also demonstrated.