Reliability and Processing Effects of Bandgap Engineered SONOS (BE-SONOS) Flash Memory

The reliability properties of BE-SONOS (Lue et al., 2005) are extensively studied. BE-SONOS employs a multi-layer O1/N1/O2/N2/O3 stack, where O1/N1/O2 serves as a bandgap engineered tunneling barrier that provides an efficient hole tunneling erase but eliminates the direct tunneling leakage. BE-SONOS can overcome the fundamental limitation of the conventional SONOS, for which fast erase speed and good data retention cannot be simultaneously achieved. This work provides a comprehensive understanding of the reliability of BE-SONOS. Various processes to form the critical O1/N1/O2 barrier, the trapping layer (N2), and the top blocking oxide (O3) are investigated. The results of this work provide design and processing guidelines for optimizing the performance and reliability of BE-SONOS flash memory devices.