氮化矽快閃記憶體中資料儲存模式 對內部電荷橫向傳輸之影響

Abstract

本篇論文中，我們採用量測隨機電報雜訊之實驗方式來分析電洞在氮化矽快閃記憶體中之橫向傳輸機制。此方法之原理如下：利用量測隨機電報雜訊時間常數受到其對應之氧化層中缺陷電位改變造成之變化，藉此探測氮化矽儲存層內部電荷的橫向移動程度。我們經由在元件上施加不同汲極電壓、並在不同溫度下重覆實驗等方法探討電荷橫向傳輸之電場效應及溫度效應。藉由分析實驗結果並與不同橫向傳輸機制之特性相互對照，我們推論在氮化矽層中儲存電荷的橫向移動機制為「熱助穿隧」模型。此外，本文也討論了我們如何利用量測隨機電報雜訊等多種實驗方式探討不同電荷儲存模式對於氮化矽快閃記憶體內部電荷橫向傳輸之影響。根據實驗結果，我們將在單一元件中特定電荷儲存模式所呈現嚴重導通電壓飄移之現象歸因於內部儲存電洞之橫向移動。

In this work, we look into the nitride trapped charge lateral transport in a SONOS cell using a novel random telegraph noise method. The exponential dependence of the random telegraph noise time constant on the local channel potential change is utilized to probe the nitride trapped charge lateral movement. The electric field and temperature dependence of charge lateral transport are analyzed by applying various drain voltages and different bake temperatures to a SONOS cell. We compare our measurement results to different charge transport mechanisms and find thermally assisted trap-to-band tunneling to be the main mechanism of trapped charge lateral transport. Furthermore, the data pattern effect on nitride trapped charge lateral migration in single SONOS cell is investigated using random telegraph noise method and other monitors. The more evident Vth loss in certain stored data pattern is attributed to trapped hole lateral migration in the shared nitride trapping layer.