Hot-Electron Capture for CHEI Programming in SONOS-Type Flash Memory Using High- $k$ Trapping Layer

In this paper, electron-energy- and lattice- temperature-dependent hot-electron-capture properties have been investigated for polysilicon-oxide-nitride-oxide-silicon-type Flash memories using a Si₃N₄ and high-dielectric-constant (k) ZrO₂/HfO₂ charge trapping layer when channel hot-electron injection is applied for programming. Hot-electron-capture rate is extracted by using an electrical method for various devices, and its lattice-temperature dependence indicates that inelastic phonon scattering may be the dominant mechanism of hot-electron relaxation. Memory device using a ZrO₂ charge trapping layer shows enhanced electron capture from extended Si_xZr_1-xO₂ interface of ~2 nm due to more sufficient scattering, and the programming speed of ZrO₂ device is enhanced as compared to HfO₂ by ~2.2 times and Si₃N₄ by ~3.2 times. Capabilities of low-voltage operation and improved endurance property are also demonstrated for ZrO₂ device as compared to the other contending NOR-type devices.