(BaxSr1-x)Ti1+yO3+z interface contamination and its effect on electrical properties

Surface contamination and cleaning processes of (BaxSr1-x)Ti1+yO3+z(BST) and Pt films were investigated using in situ, real-time mass spectroscopy of recoiled ions (MSRI). MSRI analysis revealed that BST film surfaces exposed to atmospheric ambient are contaminated with carbon and hydrogen containing species, which could be removed by thermal decomposition/desorption in an oxygen ambient. Cleaning of the BST surface was accomplished by annealing at 500 degrees C in greater than or equal to 1 mTorr O-2, resulting in complete elimination of these species. Similar contamination on Pt film surfaces could be eliminated with only 200 degrees C annealing in 5 x 10(-4) Torr of O-2. Annealing of the BST film surface in oxygen prior to deposition of the top Pt electrode results in a clean top Pt/BST interface that yields BST capacitors with much lower and more symmetric leakage current characteristics, and lower dielectric losses compared to BST capacitors with contaminated top Pt electrode/BST interfaces. (C) 2000 American Institute of Physics.[S0003-6951(00)02942-9].