MOCVD Al Nanocrystals Embedded in AlOxNy Thin Films for Nonvolatile Memory

An Al-based nonvolatile memory of Al2O3/Al-rich AlOxNy/Al0.47O0.16N0.37 layered structure on SiO2/n-Si was fabricated by a simple RTP-MOCVD system without breaking vacuum. A barrier engineering with modulating TMA/NH3 ratio during deposition to form AlN and Al2O3 films for tunnel and control layer is reported. The Al-rich AlOxNy films containing excess Al nanocrystals were utilized for charge storage layer. In order to find optimal condition, the Al-rich AlOxNy films were deposited at various temperatures. From TEM data, the charge storage films deposited at 560 degrees C to 700 degrees C contain Al NCs with size of 2 nm to 20 nm embedded in AlOxNy matrix. In XPS analysis, the metallic Al increases as deposition temperature decreasing, whereas, the AlN increases as deposition temperature increasing. For tunnel layer, mole fraction of (AlN)(0.87)(Al2O3)(0.13) can be estimated from of XPS spectra. For control layer, the atomic concentration of Al and O elements is about 39% and 61% from XPS data. Among these nonvolatile memories, the device with charge storage layer deposited at 600 degrees C has the best performance. The reliability characteristics can also be explained by the above structure and composition analysis. (C) 2012 The Electrochemical Society.