Improvement in the electrical properties of a (Ba, Sr)TiO3 capacitor by inserting a TiN layer between polycrystalline Si and Pt bottom electrodes

The crystal structure and electrical properties of a (Ba, Sr)TiO3 (BST) film on a polycrystalline Si (poly-Si) Pt electrode were investigated by inserting a Ti or TiN layer between the poly-Si and Pt. On the poly-Si/TiN/Pt bottom electrode, BST has dominantly (111) oriented grains on the (111) oriented Pt electrode and the interface study shows that the TiN prevents effectively the interdiffusion of poly-Si, Pt and BST, resulting in a dielectric constant which is three times the value of 110 for a poly-Si/Ti/Pt/BST/Pt capacitor, and the leakage current behaviour is also significantly improved by the interposition of TiN between the poly-Si and the Pt. These improvements are ascribed to the role of TSI in preventing interfacial defects and oxygen deficiency at the interface of BST and Pt.