A Novel Hot-Electron Programming Method in a Buried Diffusion Bit-Line SONOS Memory by Utilizing Nonequilibrium Charge Transport

We propose a new hot-electron programming method with a low drain-to-source voltage in a buried-diffusion (BD) bit-line SONOS memory array. In this method, channel electrons are preaccelerated in a cell preceding a program cell. For a small bit-line width, some energetic electrons will traverse an n⁺ BD region and enter a program cell with residual energy due to nonequilibrium transport. Our measurement result shows that this residual energy can significantly enhance hot-electron programming efficiency even at a V _ds of 2.5 V. The concept of this method is verified by means of a Monte Carlo analysis. Our study shows that this method is more effective as a bit-line width reduces.