High-K Materials for Nonvolatile Memories

Nonvolatile memories based on charge storage currently dominate the high density data flash market. Multi-level floating gate in NAND array architecture as well as NROM dual bit feature lowest cost per bit and simplicity of processing and thus are likely to have largest market share. For sub 50nm flash scaling introduction of high K dielectrics will be probable. High-K materials allow for improved coupling of the word line to the floating gate still providing sufficiently large physical thickness for reliable retention properties. In this article we review the opportunities and improvements high-K materials can offer for floating gate type devices as well as for charge trapping devices such as SONOS and NROM.