近年來，奈米點的應用發展與基礎研究受到相當大的矚目，尤其當奈米點運用於非揮發性記憶體時，可以解決傳統上利用複晶矽浮停閘做為載子儲存單元的非揮發性記憶體(例如，快閃記憶體)之元件微縮問題，例如:在經過多次資料讀取與寫入過程中所造成的穿隧氧化層漏電路徑，將使得儲存單元中的電荷全部流失，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，這些問題也深深影響著非揮發性記憶體的應用性。但若以奈米點取代浮停閘結構可以解決上述問題，因為電荷僅儲存於分離的奈米點中，若穿隧氧化層存在局部的漏電路徑，並不會導致電荷的全部流失，仍能維持記憶元件之功能。
金屬奈米點的特色主要有高狀態密度、強通道耦合能力、可調變金屬功函數以及不易受載子侷限效應所引起的能階擾動。在元件設計上金屬奈米點不但可減少操作電壓、增加抹除寫入速度與電子保存時間。本論文主要以金屬鈷以及鈷的矽化物作為記憶體儲存元件材料來作研究，利用高溫爐管氧化、快速退火等各項條件形成奈米點，並用材料分析與電性分析來研究奈米點的電荷儲存效應。

In recent years, the fundamental researches on nanocrystals have been received increasing attentions for the novel applications, especially the nonvolatile memory technology. Adoption of nanocrystals technology could solve the serious limitation suffered by the conventional nonvolatile memory, flash, while scaling down. Once the thin tunneling oxide of flash device has been created a leaky path, all the stored charge in the floating gate will be lost after numerous counts of data reading and writing. Hence, the thinning of tunneling oxide will become one of important keys to the scaling limitation. Furthermore, if the tunneling oxide can not be thinned any more, both the operation voltage and speed of memory can not be improved. These drawbacks will restrict the development of nonvolatile memory.
Replacement of floating gate structure with nanocrystals could effectively avoid the data losing due to the leaky path in the thin tunneling oxide. All stored charges can’t be lost through the few leaky paths since the charges are stored in distributed nanocrystals. The charges stored nearby the leaky path will be lost, but others are still kept in the distributed and independent nanocrystals.
The advantages of metal nanocrystals has have higher density of states around Fermi level, stronger coupling with conduction channel, wide range of available work functions and smaller energy perturbation due to carrier confinement. So metal nanocrystals can reduce operate voltage, and increase write/erase speed and endurance.
In this thesis, we will study of cobalt and cobalt-silicide as the memory storage element. The nanocrystals were formed by high temperature oxidation or metal rapid thermal annealing with all kinds of conditions. And we analyze the effect of electron storage at metal nanocrystals by means of material and electrical analysis.

Acknowledgment………………………………………………………i
Chinese Abstract……………………………………………ii
English Abstract……………………………………………………iv
Contents………………………………………………………………vi
Table Captions………………………………………………………ix
Figure Captions………………………………………………………x

Chapter 1 Introduction
1.1 General Background……………………………………………1
1.1.1 SONOS nonvolatile memory devices……………………3
1.1.2 Nanocrystal nonvolatile memory devices
(semiconductor nanocrystals)……………………………5
1.1.3 Nanocrystal nonvolatile memory devices
(metal nanocrystals)……………………………………10
1.2 Motivation……………………………………………………12
1.3 Organization of the dissertation…………………………13

Chapter 2 Characteristic of Cobalt-Silicide Nanocrystals
Memories Structures with Different Fabrication
processes
2.1 Introduction…………………………………………………15
2.2 Experimental procedures………………………………………17
2.2.1 The Oxidation of the Dry Oxide/Cobalt/amorphous
Silicon Structure……………………………………………17
2.2.2 The Oxidation of the Dry Oxide/Cobalt/amorphous
Silicon/Silicon Dioxide/amorphous Silicon
Structure……………………………………………………18
2.2.3 The Oxidation of the Dry Oxide/Cobalt/amorphous
Silicon/TEOS Oxide Structure…………………………20
2.3 Results and discussions………………………………………22
2.3.1 The Material Characteristic and Electrical
Characteristics of the Dry Oxide/Cobalt/amorphous
Silicon Structure……………………………………………22
2.3.2 The Material Characteristic and Electrical
Characteristics of the Dry Oxide/Cobalt/amorphous
Silicon/Silicon Dioxide/amorphous Silicon
Structure………………………………………………………23
2.3.3 The Electrical Characteristics of the Dry
Oxide/Cobalt/amorphous Silicon/TEOS Oxide
Structure………………………………………………25
2.4 Summary……………………………………………………26

Chapter 3 A Novel Approach of Fabricating Cobalt
Nanocrystals for Nonvolatile Memory Application
3.1 Introduction…………………………………………………28
3.2 Experimental procedures……………………………………29
3.2.1 The Annealing of the Dry Oxide/Cobalt/ TEOS Oxide
Structure…………………………………………………29
3.2.2 The Oxidation of the Dry Oxide/Cobalt/ TEOS Oxide
Structure…………………………………………………31
3.3 Results and discussions……………………………………33
3.3.1 The Electrical Characteristics of the Annealing of
the Dry Oxide/Cobalt/ TEOS Oxide Structure…………33
3.3.2 The Electrical Characteristics of the Oxidation of
the Dry Oxide/Cobalt/ TEOS Oxide Structure…………34
3.4 Summary……………………………………………………34

Chapter 4 Novel design of Cobalt -Silicide Nanocrystals
Structures with Nanosphere Template Technology
4.1 Introduction…………………………………………………35
4.2 Experimental procedures……………………………………35
4.3 Results and discussions……………………………………37
4.4 Summary……………………………………………………38

Chapter 5 Conclusions and Suggestion for Future Work
5.1 Conclusions…………………………………………………39
5.2 Suggestion for Future Work…………………………………40

Reference……………………………………………………………42
Note…………………………………………………………………47

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