臺灣博碩士論文加值系統

砷化銦鎵半導體的高遷移率對於高速互補式金屬氧化物元建中是一極有潛力之通道材料,而在互補式金屬氧化物元件的製成當中,如何有效降低源 極以及汲極的接觸電阻是非常關鍵的一個議題《尤其是在小尺寸的元件當中《 接觸電阻對於元件效能的影響更為重大〈有鑑於此《鈀/鍺/鈦/鉑在砷化銦鎵半導體上的歐姆介面在這篇論文中《達成了對於接觸電組之最佳化以及對於歐姆 介面形成做了完整的材料分析〈
經由分子束磊晶技術《不同比例的砷化銦

InxGa1-xAs semiconductors are now potential candidates for high-speed complementary metal oxide semiconductor (CMOS) devices due to their high electron mobility. One of the key issues of fabricating high performance CMOS is to lower the contact resistance, which is the dominant component in the highly scaled devices. In this work, Pd/Ge/Ti/Pt metal system had been fabricated on n-InxGa1-xAs (x=0, 0.2, 0.53) layers for achieving low contact resistivity with planar metal-semiconductor interface.
A solid-source GaAs-based III-V molecular beam epitaxial (MBE) was used to grow GaAs, In0.2Ga0.8As and In0.53Ga0.47As epilayers. The samples were rapid thermal annealed (RTA) at various temperatures from 300°C to 400°C for 10 to 90 seconds after the deposition of Pd/Ge/Ti/Pt metals. Transmission line method (TLM) was used to extract the specific contact resistivity (ρc) and sheet resistance (Rs).
With the optimized Ge thickness and RTA condition, the lowest ρc attained on n-GaAs and n-In0.2Ga0.8As are 1.2×10-6 ohm-cm2 and 5.4×10-7 ohm-cm2 respectively. For n-In0.53Ga0.47As, ρc could even reach as low as 1×10-7 ohm-cm2. Moreover, X-ray diffraction (XRD), transmission electron microscope (TEM) and energy-dispersive X- ray spectroscopy (EDS) have also been used to analyze the mechanism of forming ohmic contacts on n-InxGa1-xAs. The results have demonstrated that the Pd/Ge/Ti/Pt metal system could to be readily applied to MOSFETs for the ohmic contact on the re- grown source/drain or ion-implanted source/drain with appropriate activation temperature.

中 文 摘 要 ................................................................................................... I Abstract ....................................................................................................II 致 謝 ........................................................................................................ III Table of Contents .................................................................................. IV Table Captions......................................................................................VII Figure Captions .................................................................................. VIII
Chapter 1 Introduction...........................................................................1 1.1 Research background ...................................................................................1 1.2 Motivation......................................................................................................3
Chapter 2 Instrumentation and Theories .............................................6
2.1 Molecular beam epitaxy ...............................................................................6
2.1.1 Multi-Chamber MBE system.............................................................6 2.1.2 Reflection High Energy Electron Diffraction21 ................................7 2.1.3 Residual Gas Analyzer .....................................................................11
2.2 Electrical analysis of Metal-Semiconductor contact................................13
2.2.1 Metal-Semiconductor contact..........................................................13 2.2.2 Contact resistance .............................................................................15 2.2.3 Transmission line model (TLM) ......................................................19
2.3 Etching principles of acid solutions...........................................................24
2.3.1 Native Oxide Removal by Using Hydrochloric Acid .....................24
2.3.2 Etching principles of GaAs with sulfuric acid/hydrogen peroxide/water solution .............................................................................26
2.4 X-ray diffraction .........................................................................................26
2.5 Transmission Electron Microscope (TEM) ..............................................27
2.6 Energy-dispersive X-ray spectroscopy (EDS) ..........................................27
2.7 Hall measurement ....................................................................................... 28

Chapter 3 Experimental Procedure.....................................................30 3.1 Highly Doped III-V Layer Growth Process in MBE System..................30 3.2 Ohmic Contact Metal Deposition on TLM pattern regions....................32 3.3 Measurement of Specific Contact Resistivity ...........................................34 3.4 Micro-structure Analyses...........................................................................34
3.4.1 X-ray Diffraction (XRD) .................................................................34
3.4.2 High Resolution Transmission Electron Microscope (HRTEM).35 Chapter 4 Results and Discussion........................................................36
4.1 The Optimization and Investigation of the Pd/Ge/Ti/Pt Metals on n- GaAs Layer.........................................................................................................36
4.1.1 Optimization of Contact Resistivity with Various Thickness Ratio of Pd/Ge on n-GaAs ...................................................................................36
4.1.1.1 Pd(30nm)/ Ge(15nm)/ Ti(30nm)/ Pt(30nm) deposited on n-GaAs..37
4.1.1.2 Pd(30nm)/ Ge(30nm)/ Ti(30nm)/ Pt(30nm) deposited on n-GaAs..38
4.1.1.3 Pd(30nm)/ Ge(60nm)/ Ti(30nm)/ Pt(30nm) deposited on n-GaAs..41
4.1.1.4 Pd(30nm)/ Ge(30nm) deposited on n-GaAs ....................................43
4.1.1.5 Comparison of specific contact resistivity with different Pd/Ge ratio and RTA conditions on n-GaAs...................................................................45
4.1.2 Phase Identificaiton of the Pd/Ge/Ti/Pt on n-GaAs with different RTA conditions...........................................................................................47
4.2 The Optimization and Investigation of the Pd/Ge/Ti/Pt Metals on n- In0.2Ga0.8As Layer ..............................................................................................50
4.2.1 Optimization of Contact Resistivity with Various Thickness Ratio of Pd/Ge on n-In0.2Ga0.8As.........................................................................50
4.2.1.1 Pd(30nm)/ Ge(15nm)/ Ti(30nm)/ Pt(30nm) deposited on n- In0.2Ga0.8As ..................................................................................................50
4.2.1.2 Pd(30nm)/ Ge(30nm)/ Ti(30nm)/ Pt(30nm) deposited on n- In0.2Ga0.8As ..................................................................................................52
4.2.1.3 Pd(30nm)/ Ge(60nm)/ Ti(30nm)/ Pt(30nm) deposited on n- In0.2Ga0.8As ..................................................................................................54
4.2.1.4 Pd(30nm)/ Ge(30nm) deposited on n-In0.2Ga0.8As ..........................56
...................................................................................................................... 56
4.2.1.5 Comparison of specific contact resistivity with different Pd/Ge ratio and RTA conditions on n-In0.2Ga0.8As.........................................................57
4.2.2 Strucural Investigation of the Relation between Contact Resistivity and Annealing Conditions on n-In0.2Ga0.8As ........................60
4.2.2.1 Phase Identificaiton of the Pd/Ge/Ti/Pt on n-In0.2Ga0.8As with different RTA conditions .............................................................................60
4.2.2.2 Cross-section Structural Investigation of Pd/Ge/Ti/Pt on In0.2Ga0.8As with Various RTA Conditions Using TEM .................................................63
4.2.3 The Migration of Germanium Atoms on In0.2Ga0.8As during Rapid Thermal Annealing.........................................................................66
4.3 Comparison with other results on n-GaAs with short time annealing ...68
4.4 The Optimization and Investigation of the Pd/Ge/Ti/Pt Metals on n- In0.53Ga0.47As Layer............................................................................................70
4.4.1 Optimization of Contact Resistivity with Various Thickness Ratio of Pd/Ge on n-In0.53Ga0.47As ...................................................................... 70
4.4.1.1 Pd(60nm)/ Ge(60nm)/ Ti(30nm)/ Pt(30nm) deposited on n- In0.53Ga0.47As ................................................................................................ 70
4.4.1.2 Comparison of specific contact resistivity with different Pd/Ge ratio and RTA conditions on n-In0.53Ga0.47As ......................................................71
4.4.2 Phase Identificaiton of the Pd/Ge/Ti/Pt on n-In0.53Ga0.47As with different RTA conditions...........................................................................73
4.5 Comparison with other results on n-In0.53Ga0.47As with short time annealing ............................................................................................................. 76
Chapter 5 Conclusion............................................................................78 Reference ................................................................................................. 80

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