臺灣博碩士論文加值系統

此論文的研究主題之ㄧ，為針對含鉑之鎳矽化物(Ni silicides)形成在矽碳磊晶層(epi-SiC)上之生成反應進行研究，我們發現，碳原子的存在將使得矽化鎳(NiSi)的成長動力學受到延遲，且將有效的改善矽化鎳薄膜之熱穩定性。此外，值得注意的是，在鎳矽化物形成的過程當中，我們還觀察到了不尋常的碳分布形況，實驗結果顯示，在金屬矽化(silicidation)過程，碳原子將聚集並累積在試片的中心位置，並使得矽化鎳被分成上下兩層。我們提出一個機制以解釋上述現象，並說明碳原子在鎳矽化物相變化過程中所扮演的角色，在金屬矽化過程，碳原子將會填充並占據在矽化鎳與矽化二鎳(Ni2Si)介面間，及矽化鎳晶粒邊界，並扮演一個擴散障礙(diffusion barrier)的角色，進而限制矽化鎳的晶粒成長與結塊(agglomeration)現象，並使得低電阻矽化鎳相的製程溫度範圍變得更加寬廣。
除了上述實驗，我們也針對不含鉑之鎳矽化物形成在矽碳磊晶層上之過程進行研究。此系統與含鉑系統最主要的差別在於，我們發現矽化鎳剛形成時，會在矽化二鎳層與矽基板介面處產生如金字塔狀的區域，這將使得矽化鎳完全生成時，碳原子的分布較不集中，而在含鉑的系統，矽化鎳的生成經由單一個非常平整的介面，這將使得碳原子被從矽化鎳排出時，集中的在一個平整的介面區域。另外，此實驗亦證實矽碳磊晶層在金屬矽化的過程，不但不會使應變(strain)被釋放，還會使應變進一步被增加，此結果證實，為了元件上的應用，將鎳矽化物形成於矽碳磊晶層之上是非常可行的。
最後一項實驗，我們有系統的研究鋁對於鎳矽化物形成於矽基板之影響。我們發現，鋁原子的加入將使得矽化二鎳轉換成矽化鎳的退火溫度變高，而使矽化鎳轉換成二矽化鎳(NiSi2)的退火溫度變低，並且將有效的改善矽化鎳之高溫結塊現象。我們利用了擴散障礙與晶格匹配度的角度，來解釋鋁如何使得矽化二鎳轉換成矽化鎳的退火溫度變高，而使矽化鎳轉換成二矽化鎳的退火溫度變低。此外，我們也提出一些說法以解釋鋁原子如何改善矽化鎳之高溫結塊現象。

One of this study investigates the formation of Ni(Pt) silicides on Si1-yCy (0.008≦ y≦ 0.02) epilayers grown on Si(001). The presence of C atoms retards the growth kinetics of NiSi and significantly enhances the thermal stability of NiSi thin films. In particular, an abnormal redistribution of C atoms in the NiSi thin films was observed during Ni silicidation. The NiSi layer was split into two sublayers by an obvious pile-up of C atoms. This study proposes a mechanism to elucidate this phenomenon in terms of the C solubility. C atoms accumulated at the NiSi/Si1-yCy interfaces and NiSi grain boundaries may act as diffusion barriers, effectively hindering the grain growth and agglomeration of NiSi and extending the process window of low-resistivity NiSi silicides.
In addition, the formation of Ni silicides on Si1-yCy epilayers grown on Si(001) was also investigated. It should be noted that, in our previous study, the Ni(Pt)Si layer was split into two sublayers by an obvious and narrow piles-up of C atoms. It is because the initial Ni(Pt)Si phase started with a planar structure (NiSi pyramids in this work), which effectively expelled C atoms to the planar Ni2Si/NiSi interface. In addition, HRXRD analysis shows an additional strain introduced into the Si1-yCy layers during Ni silicidation. This work demonstrates the potential of Ni silicidation on Si1-yCy epilayers for device applications.
On the other hand, the formation of Ni-Al alloy silicides on (001)Si has been systematically investigated in this study. The presence of Al atoms was found to significantly slow down the Ni2Si-NiSi phase transformation and speed up the NiSi-NiSi2 phase transformation during annealing. The addition of Al atoms also suppresses the suddenly increase in sheet resistance. We propose some explanations to depict this phenomenon and elucidate the role of Al atoms in the phase transformations.

CHAPTER 1 Introduction 1
1.1 An Overview 1
1.2 Salicide Process for CMOS Devices 3
1.3 Introduction to Silicides 5
1.4 Advantages of Nickel Silicides 12
1.5 High Temperature Limitations of Nickel Silicides 15
1.6 Channel Strain Engineering for CMOS Technology 17
1.7 Effects of Third Element on Ni Silicide Formation 23
References 25
CHAPTER 2 Experimental 33
2.1 Sheet Resistance Measurement 33
2.2 High Resolution X-ray Diffraction Analysis 34
2.3 Transmission Electron Microscope Observation 36
2.4 Scanning Electron Microscope Observation 37
CHAPTER 3 C Redistribution during Ni(Pt) Silicide Formation on Si1−yCy Epitaxial Layers 38
3.1 Motivation 38
3.2 Experimental Details 39
3.3 Results and Discussion 40
3.4 Conclusions 50
References 51
CHAPTER 4 The Effects of C on the Solid-Phase Reaction of NiSi1-yCy Systems 55
4.1 Motivation 55
4.2 Experimental Details 56
4.3 Results and Discussion 57
4.4 Conclusions 67
References 68
CHAPTER 5 Study of Ni/Si(001) solid-state reaction with Al addition 71
5.1 Motivation 71
5.2 Experimental Details 72
5.3 Results and Discussion 73
5.4 Conclusions 84
References 85
CHAPTER 6 Conclusions 89
6.1 C Redistribution during Ni(Pt) Silicide Formation on Si1−yCy Epitaxial Layers 89
6.2 The Effects of C on the Solid-Phase Reaction of NiSi1-yCy Systems 89
6.3 Study of Ni/Si(001) solid-state reaction with Al addition 90

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