最近幾年來，次世代非揮發性記憶體的發展備受關注，由於快閃記憶體在微縮尺寸的過程中，遇到物理理論的瓶頸，所以次世代非揮發性記憶體的研究與開發正蓬勃地展開。其中，又以電阻式非揮發性記憶體元件具有結構簡單、耗損能量低、操作電壓低、製作密度高、操作速度快、耐久度高、儲存時間長和非破壞性存取等優點，使其成為取代快閃記憶體的大熱門。
在本研究中，將焦點著重於以金屬鎢的相關氧化物製作成具有電阻式記憶體特性的元件。由於，金屬鎢已經廣泛應用在CMOS 的製程中，所以它在CMOS 製程上有相當好的相容性。第一部分的實驗，主要是用氧化鎢當成電阻式記憶體元件的轉換特性層，我們也成功的製作出具轉態特性的元件。然而，它的元件特性卻極不穩定，也就是說高阻態跟低阻態的不穩定性。再經過操作100 次後，元件的記憶窗口明顯的縮小了一個數量級，這樣不穩定的元件是不能大量生產的。與鎢氧化物相比，我們就將以鎢矽氧化物當做電阻式記憶體元件的轉態特性層，當然也成功的製作出具轉態特性的元件。從實驗結果來看，再經過100 次的操作後，它的元件仍保持相當好的記憶特性，且經過AC 模式的十萬次操作後，並在高溫下可以持續保有其記憶特性。並且藉由材料分析的方法來分析薄膜成分、建立機制。
第二部分，更進一步想要藉由控制金屬鎢在薄膜中的含量，使得金屬絲的產生跟斷裂可以選擇的路徑更少去得到穩定的操作特性；另一方向想要藉由雙層結構中，氮原子的孤電子對來侷限氧離子的移動，使得RRAM 的切換特性可以得到更有效的改善，並在可靠度的測試上達到10000000 次的切換。兩者在高溫的穩定性都可以維持得很好。
在第三部分的實驗，最後我們藉由I-V 曲線來探討其電流機制，並在高阻態的高電場部分發現了不對稱的電流機制，並藉此提出了一個尖端電場的產生，使得元件在正負偏壓下的高電場有不同的載子傳輸機制。另外，結合示波器跟脈衝產生器去設計出一個等效電路，並且進行變溫量測。實驗結果顯示，RRAM 在轉換的過程中是需要一個臨界電壓跟能量。變溫的結果發現，低溫的時候氧離子的移動是跟電場有關；在高溫之下則是與氧離子的熱擴散有關。

In recent years, the conventional Flash memory with floating structure is expected to reach physical limits as devices scaling down in near future. In order to overcome this problem, alternative memory technologies have been widely investigated. And the
resistance random access memory (RRAM) has attracted extensive attention for the application in next generation nonvolatile memory, due to the excellent memory property including lower consumption of energy, lower operating voltage, higher density, fast operating speed, simple structure, higher endurance, retention and process compatibility with CMOS.
In this study, the tungsten-based oxide is chosen as RRAM switching layer because the tungsten is compatible with the present complementary metal oxide semiconductor (CMOS) process. The Pt/WOX/TiN structure device cells had the resistance switching property successfully. However, the experiment result revealed the inferior resistance
switching property. The resistance switching characteristic of the WOX thin film is extremely unstable, it is impossible to become the products. Compared with WOX, the resistance switching property of WSiOX RRAM device is improved substantially such as stability of resistance states and reliability of device.
In second parts, we purposed two methods to enhance the device switching characteristic, including controlling the filament formation/ interruption in the W doped SiOX layer and restricting oxygen movement in the WSiON layer.
Finally, the transport mechanisms of carrier is analyzed and researched from the current-voltage (I-V) switching characteristic of the device. A designed circuit was used in this study to accurately observe the resistance switching process with a pulse generator and oscilloscope, which reveals that the switching process is related to both time and voltage. The oxygen movement will drift in the low temperature due to the electrical field and restricted the crystal lattice vibration. But, it will diffuse through thermal dynamics in the high temperature.

Contents
Acknowledgement………...................................................ii
Abstract (Chinese) ……………………………………………………………....iii
Abstract (English) …………………………………. v
Contents…………………………………………………...vii
Figure captions……….........................................................x
Table captions……...........................................................xvii
Chapter1 Introduction
1-1.The evolution of memory 1
1-2.Motivation 2
Chapter2 Literature
2-1.The introduction of memory 3
2-1-1.MRAM (Magnetic RAM) 4
2-1-2.FeRAM (Ferroelectric RAM) 6
2-1-3.PCRAM (Phase Change RAM) 7
2-1-4.RRAM (Resistance RAM) 8
2-2.The materials of Resistance RAM 9
2-2-1.Perovskite 9
2-2-1-1.Pr0.7Ca0.3MnO3 10
2-2-1-2.SrTiO3 and SrZrO3 11
2-2-2.Transition metal oxides 12
2-2-3.Organic materials 13
2-3.The switching mechanism of Resistance RAM 14
2-3-1.Filamentary model 14
2-3-1-1.Joule heating effect 15
2-3-1-2.Redox reaction with cation migration 16
2-3-1-3.Redox reaction with anion migration 17
2-3-2.Modified Schottky barrier model 18
2-4.The mechanism of current conduction 19
2-4-1.Ohmic conduction 20
2-4-2.Schottky emission 20
2-4-3.Poole-Frenkel emission 21
2-4-4.Tunneling conduction 22
2-4-5.Space charge limited current 22
2-5.Material Analyses 23
2-5-1.X-ray Photoelectron Spectroscopy (XPS) 23
2-5-2.Fourier Transform Infrared Spectroscopy (FTIR) 24
Chapter3 Resistance RAM characteristics of WOX and WSiOX
3-1.Results for Pt/WOX/TiN 39
3-1-1.Experimental procedures 39
3-1-2.Basic characteristic of WOX 40
3-2.Material Analyze for Pt/WOX/TiN 41
3-2-1.Fourier Transform Infrared Spectroscopy (FTIR) 41
3-2-2.X-ray Photoelectron Spectroscopy (XPS) 42
3-3.Results for Pt/WSiOX/TiN 43
3-3-1.Experimental procedures 43
3-3-2.Basic characteristic of WSiOX 44
3-3-3.Endurance and retention 45
3-4.Material Analyze for Pt/WSiOX/TiN 47
3-4-1.Fourier Transform Infrared Spectroscopy (FTIR)
47
3-4-2.X-ray Photoelectron Spectroscopy (XPS) 48
3-5.Discussion 49
Chapter4 Resistance RAM characteristics of W:SiOX and WSiON/WSiO double layer films
4-1.Results for Pt/W:SiOX/TiN 67
4-1-1.Experimental procedures 67
4-1-2.Basic characteristic of W:SiOX 68
4-1-3.Endurance and retention 69
4-2.Material Analyze for Pt/W:SiOX/TiN 71
4-2-1.Fourier Transform Infrared Spectroscopy (FTIR) 71
4-2-2.X-ray Photoelectron Spectroscopy (XPS) 72
4-3.Results for Pt/WSiO/WSiON/TiN (bilayer structure) 4-3-1.Experimental procedures 74
4-3-2.Basic characteristic of bilayer structure 75
4-3-3.Endurance and retention 76
4-4.Material Analyses 78
4-4-1.Fourier Transform Infrared Spectroscopy (FTIR) 78
4-4-2.X-ray Photoelectron Spectroscopy (XPS) 79
4-5.Discussion 80
Chapter5 Research of Resistance RAM mechanism
5-1. Analyses of carrier transport mechanism 100
5-2. Discusion for carrier transport mechanism 101
5-3. Energy model of Resistance Switching 102
5-4. Discusion for Energy model of Resistance Switching 105
Chapter6 Conclusion 124
References 129

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