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

We report the impact of high work-function (/spl Phi//sub M/) metal gate and high-/spl kappa/ dielectrics on memory properties of NAND-type charge trap Flash (CTF) memory devices. In this paper, theoretical and experimental studies show that high /spl Phi//sub M/ gate and high permittivity (high-/spl 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 /spl Phi//sub M/ gate and high-/spl kappa/ materials, enhanced CTF device characteristics such as high speed, large memory window, and good reliability characteristics of the CTF devices are obtained.