Abstract
電子幫浦方法曾廣泛被用來討論熱電子注入造成的傷害，在本篇論文中則利用電荷幫浦方法來研究快閃式記憶體在不同拭去條件下所造成的拭 去退化。在快閃式記憶體的操作下（寫入及拭去），寫入是利用熱電子注入的方式，拭去則基本上想利用Ｆ－Ｎ穿遂效應。但伴隨著此效應的同時，還有能帶對能帶穿遂發生。此效應的產生，使得在閘極和ｎ＋區域之間有電子電洞對產生。電子由源極流回，電洞則經空乏區流出。但由於空乏區的電場，使電洞在此區之氧化矽－基板介面間造成破壞，甚至電洞會得到足夠能量而衝入氧化矽，這是拭去時所不願見到的。此次實驗是藉著不同源極電壓組合來拭去，利用電荷幫浦方法去觀察在介面間所造成的破壞。同時也做多次反覆寫入拭去實驗，觀察不同拭去條件組和造成拭去退化的不同。結果我們可以看到不同的源極電壓確實造成不同的拭去破壞（由於能帶對能帶穿遂時電洞的產生及流經空乏區所造成），但是它們的電性參數，如Ｇｍｍａｘ 及 Ｖｔ 卻不因此而改變，這可以說明這些破壞是落在 ｎ＋ 及 ｎ－ 區域而非通道上，因此並不會改變電性參數。此外由多次反覆寫入拭去實驗結果顯示，不同拭去條件（源極電壓組合）造成的拭去退化是相同的，雖然它們所造成的拭去破壞是不同的，這說明了拭去破壞和介面間破壞的相關度不大，可能的原因是，拭去退化主因來自氧化矽內的缺陷（ｔｒａｐ）。此外在本實驗中我們亦得到一個結果，就是對同樣電子數流經氧化矽而言，Ｆ－Ｎ的破壞要比熱電子注入的破壞來的大。A charge pumping technique has been used to explore thedegradation of the flash EPROM cell due to the erase. Althoughthe Fowler-Nordheim tunneling is employed for the erase, it isfound that the band-to-band tunneling induced hot holeinjection is the dominant mechanism for the degradation due tothe erase. Three different source bias Vs has been used tostudy the effect of these band-to-band tunneled hot holes. Highlevel of damages is observed for the large Vs bias. Besidesthe charge pumping method, the degradation of the programmingand erasing window and the triode region transconductance Gmmaxdue to cycles of grogramming and erasing has also beenperformed on the flash EPROM used in practice. The resultsshow that damages due to erasing sare greater than those due toprogramming. No discernible extra degradation of theelectrical parameters such as the Gmmax and the thresholdvoltage has been observed although a very large change of thecharge pumping current has been observed. Thus, the chargepumping method is more sensitive as compared to othermeasurement method. The lateral distribution of the damageshas also been studied by applying a reverse bias at the drainterminal. The erase induced damages have been found to belocated mostly in the n- doublely diffused region.