Abstract
在快閃記憶元件應用中，過矽氧化層之薄膜能造成一個可靠、有效的低電壓穿隧通道.然而，迄今並無一個微觀之定量的物理模型被提出來解釋這種強化穿隧的現象，至於過矽氧化層本身的微晶體結構也無完整的研究報告出現.我們的實驗就將從過矽氧化層的微晶體結構及其薄膜特性,基本強化穿隧特性及次微米之過矽氧化層快閃記憶元件之特性及其可靠度作研究,進而提出一新的二維微觀定量的物 然而，迄今並無一個微觀之定量的物理模型被提出來解釋這種強化穿隧的現象，至於過矽氧化層本身的微晶體結構也無完整的研究報告出現.我們的實驗就將從過矽氧化層的微晶體結構及其薄膜特性,基本強化穿隧特性及次微米之過矽氧化層快閃記憶元件之特性及其可靠度作研究,進而提出一新的二維微觀定量的物理模型.首先在微晶體結構這方面來說,於高解析之電子穿隧顯微鏡，我們可以清楚的觀察到有微晶體組成的矽島存在於過矽氧化層中.在一連串雷射光激發的發光光譜中，紅移現象隨著過火的程度增加而增加.這表示微晶體的大概尺度及其結構特性.再者，過矽氧化層之微晶體結構所造成的強化穿隧特性也在金氧半電容的實驗中被探討.而我們所提出之新的二維微觀的物理模型可以定量的來解釋所觀察到的強化穿隧特性並用來了解並預測微晶體對穿隧所造成的影響.最後，一個新的過矽氧化層之NAND記憶陣列操作被提出.針對這陣列所須考慮的特性及可靠度所做的實驗發現:傳統元件所須的22伏特擦拭及寫入電壓可以分別大幅下降為7伏特及12伏特且速度增加100倍.並且經過了100000的循環寫入擦拭後其特性並不會受到影響.因此將過矽氧化層應用在降低快閃記憶元件操作電壓的可行性已被證實.Thin Silicon-Rich-Oxide (SRO) film can be an efficient andreliable tunneling injector for the low voltage application inFlash memory cell. To date, no work has been done on aquantitative and microscopic tunneling model for the SROenhancement behavior. Moreover, no complete investigation on Si-islands of SRO films have been presented. Nanocrystalline siinjector for the low voltage application in Flash memory cell.To date, no work has been done on a quantitative and microscopictunneling model for the SRO enhancement behavior. Moreover, nocomplete investigation on Si-islands of SRO films have beenpresented. Nanocrystalline silicon structure in SRO thin film isobserved from the high resolution TEM, the red-shift ofphotoluminescence (PL) spectra and increasing intensity of PLspectra after subsequent annealing. In addition, enhancedtunneling characteristics of MOS capacitor using SRO thin filmsas injectors due to nanocrystalline silicon (nc-Si) islands inSRO thin films is also observed. A new low voltage SNAND (SRONAND) Flash cell by using SRO as injectors is also proposed andinvestigated, particularly on performance characteristics andreliability issues. Furthermore, a two-dimensional microscopicmodel for SRO tunneling characteristics is also developed toquantitatively explain the tunneling enhancement characteristicsfor SRO Flash memory cell. Results show that the tunneling modelagreed well with the tunneling characteristics of SNAND cell andalso provided a insight of tunnel oxide scaling in SNAND celloperation. The erase and program voltages of Flash cell with SROinjector can be reduced from 22V to 7V and 12V with improvedspeed up to 2 orders, respectively. More than 105 endurancecycles are also achieved. The feasibility of using SRO for lowvoltage and low power Flashmemory is demonstrated .