氫含量在奈米金屬點非揮發性記憶體之影響

Abstract

近年來，使用奈米點(nano-dot)記憶胞當作電荷儲存中心已經被廣泛的研究與發展，尤其當運用於非揮發性記憶體時，可以解決傳統複晶矽浮停閘(floating gate)的非揮發性記憶體之元件微縮問題。在經過多次資料讀取與寫入過程中，會使穿隧氧化層產生漏電路徑，使得儲存單元中的電荷全部流失，而造成記憶體元件功能的失效。因此在元件微縮過程中，穿隧氧化層的厚度將成為限制了元件微縮的重要關鍵之一。再者由於穿隧氧化層的厚度無法薄化，於是操作電壓也無法降低，讀取速度也跟著無法增快，因此這些問題深深影響著非揮發性記憶體的應用性。奈米點(nano-dot)非揮發性記憶體有兩大重要研究方向，深深地影響記憶元件的效能表現，即穿隧氧化層的形成方式和奈米點之氧化成形機制。本篇論文在敘述金屬鎢奈米點記憶體電容元件的製作過程中，加入氫於快速加熱氧化腔體成長出穿隧氧化層，再用低壓化學氣相沉積(LPCVD)成長矽化鎢與非晶矽雙層薄膜，最後再以不同比例之氣體(H2/O2)高溫快速熱氧化回火方式在穿隧氧化層上方氧化形成鎢奈米點以及控制氧化層。最後由電性的量測得知，加入氫的快速氧化回火長出的穿隧氧化層和鎢奈米點，在漏電，記憶窗大小和元件穩定度都有不錯的表現。因此我們認為氫在奈米點記憶體的製作上，不論是形成穿隧氧化層或是奈米點，皆扮演著有益的角色，但是氫與氧的最佳比例還是需要日後配合不同種類的奈米點記憶體，進行實驗與分析。

In recent years, the use of nano-dot as the memory cell charge storage center has been extensive research and development, especially solve the devices shrink problem of traditional poly-crystalline silicon floating gate non-volatile memory.After several data read and write process times, the tunneling oxide layer will produce leakage paths, making the charge storage unit, all the loss of function and caused memory devices failure. Therefore, in the process of miniature components, the tunneling oxide layer thickness will be the limit of the key to one of the miniature components. Moreover, the thickness of the oxide layer due to tunneling can not be thinning, and operating voltage can not lower, speed is also not followed by fast, so these issues deeply affecting the application of non-volatile memory.There are two important research directions, deeply affecting performance on memory components, which were the formation of tunneling oxide layer and the oxidation mechanism of tungsten nano-dots. In this paper, we made a description of critical process on tunnel oxide and tungsten nano-dots. First we would add the hydrogen into process chamber to grow tunnel oxide and fabricate tungsten nano-dots by different hydrogen content (H2/O2). Finally we formed the control oxide on the top of trapping layer by thermal oxidation. After electrical measurements, we would get better performance on tunnel oxide and tungsten nano-dots by adding hydrogen into process. Not only memory window but also reliability on memory devices. Therefore, we believe that hydrogen is playing a useful role on formation of tungsten nano-dots.In order to form the high performance of nano-dots memory, we still need to make more experiment to optimum the ratio of hydrogen and oxygen.