Forward Bias Enhanced Channel Hot Electron Injection for Low-Level Programming Improvement in Multilevel Flash Memory(Integrated Electronics)

概要

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Low-voltage programmed levels are hard to achieve in multilevel Flash memory using staircase CHEI (channel hot electron injection) programming. The reasons are that low-level programming marginally deviates from the linear relation between threshold voltage V_<TH> and control gate voltage V_<CG>. Forward bias enhancement of CHEI is proposed to overcome this drawback. It is demonstrated that the new technique creates a linear relation between V_<TH> and V_<CG>, validated down to a critical V_<CG> that is at least 1 V lower than traditional CHEI. Through extensive measurements, it is further argued that the most suitable magnitude of forward bias is 0.5 V since (i) it produces the lowest program level of 1.4 V; and (ii) higher biases cause not only large current consumption but also worsened drain disturb performance in NOR array configuration. The corresponding linear relation with the unity slope is maintained after 10^5 program/erase cycling.
社団法人電子情報通信学会の論文
2004-07-01