X-ray photoemission study of CoFeB∕MgO thin film bilayers

Abstract

The authors present results from an x-ray photoemission spectroscopy study of CoFeB∕MgO bilayers where they observe process-dependent formation of B, Fe, and Co oxides at the CoFeB∕MgO interface due to oxidation of CoFeB during MgO deposition. Vacuum annealing reduces the Co and Fe oxides but further incorporates B into the MgO forming a composite MgBxOy layer. Inserting an Mg layer between CoFeB and MgO introduces an oxygen sink, providing increased control over B content in the barrier.