近年來隨著可攜式電子產品的大眾化，非揮發性記憶體(non- volatile memory, NVM)在製程技術、結構、操作機制以及可靠度上都有著快速的進步。尤其是CMOS製程的微縮，使得矽-氧化矽-氮化矽-氧化矽-矽(silicon-oxide-nitride-oxide-silicon，SONOS)記憶體元件逐漸受到矚目。與傳統的浮動閘極(floating gate)記憶體做比較， SONOS記憶體元件與現今的先進CMOS製程有著高度的整合性，較簡單的結構以及低電壓操作的特性。除此之外，由於電荷能夠局部性地儲存在SONOS記憶體元件的氮化矽層中，使得單一元件具有多位元的儲存能力。了解電荷在氮化矽層中的分佈可以去最佳化寫入操作和減少在擦寫過程中電荷對氧化層的損壞。
本篇論文主要在比較P通道與N通道SONOS元件在通道熱電子注入(CHEI) 的寫入下所表現出的儲存電荷差異性，並進一部探討兩者間的可靠度。在實驗上，我們採用順向讀取 (forward read) 和逆向讀取(reverse read) 來量測，並分別利用Tsuprem4 和 MEDICI 這兩套TCAD軟體對SONOS元件做製程及電性上的模擬。利用順向讀取和逆向讀取的差異性，藉由放置負電荷在氮化矽層中，比較量測所得到的電流－電壓曲線圖，模擬出P通道與N通道SONOS元件在寫入過程中的電荷分布。得到的實驗結果顯示出通道熱電子在P通道SONOS元件可以均勻地被注入並儲存到氮化矽層，然而在N通道SONOS元件中，電荷卻是局部地被缺陷所束縛。在可靠度上，P通道與 N通道SONOS元件分別經過耐久性(endurance)和電荷保存能力(retention)的測試與比較，P通道SONOS元件因可對通道兩端做均勻地電荷寫入/抹除操作而有較佳的可靠度。

Recently, with the portable electrical products are popularization, the non-volatile memory (NVM) devices advance fast in fabrication technology, structure, operation condition and reliability. Especially in scaling of CMOS technology, silicon-oxide-nitride-oxide-silicon (SONOS) memory devices become appealing because of their high compatibility with existing advanced CMOS technology, structural simplicity and low-voltage operation as compared to traditional floating gate memory. Besides, due to the charges can be locally trapped in the nitride layer, multi-bit storage in a unit cell can be achieved. Understanding the charge distribution of the nitride layer can help in optimizing the program operation and minimizing the oxide damages in cycling.
This thesis is studying “the different programmed charge distributions in p-channel and n-channel SONOS devices by channel hot electron injection (CHEI)” and further discusses their reliability. In this experiment, we use the forward and reverse reads to measure the location of charges in the channel, and use TCAD simulation (i.e., Medici) for comparison. Considering the difference between the forward and reverse reads in simulation, we place negative charges in the nitride layer of SONOS devices to fit the measured Id-Vd curves of SONOS devices. The programmed charge distributions of both p-channel and n-channel SONOS devices can be obtained. Therefore The result clearly shows that the channel hot electrons should be uniformly injected and stored in the nitride layer of p-channel SONOS devices, which is very different from what we know in n-channel SONOS devices. In n-channel SONOS devices the charges are locally trapped. In the endurance and retention characterizations, better reliability in p-channel SONOS device is observed as a result of the uniformly bipolar directional stresses during program/erase operations.

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