High work-function metal gate and high-κ dielectrics for charge trap flash memory device applications

We report the impact of high work-function ( Phi sub(M)) metal gate and high- Kappa dielectrics on memory properties of NAND-type charge trap Flash (CTF) memory devices. In this paper, theoretical and experimental studies show that high Phi sub(M) gate and high permittivity (high- Kappa ) dielectrics play a key role in eliminating electron back tunneling though the blocking dielectric during the erase operation. Techniques to improve erase efficiency of CTF memory devices with a fixed metal gate by employing various chemicals and structures are introduced and those mechanisms are discussed. Though process optimization of high Phi sub(M) gate and high- Kappa materials, enhanced CTF device characteristics such as high speed, large memory window, and good reliability characteristics of the CTF devices are obtained.