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系統識別號 U0026-2807202012022100
論文名稱(中文) 於可撓式基板上研製具有高介電係數介電層之氧化銦錫鋅薄膜電晶體
論文名稱(英文) Investigations of Indium-Tin-Zinc-Oxide Thin-Film Transistors with High-k Dielectrics on Flexible Substrate
校院名稱 成功大學
系所名稱(中) 微電子工程研究所
系所名稱(英) Institute of Microelectronics
學年度 108
學期 2
出版年 109
研究生(中文) 李宜靜
研究生(英文) Yi-Jing Li
學號 Q16074134
學位類別 碩士
語文別 英文
論文頁數 73頁
口試委員 指導教授-許渭州
共同指導教授-劉漢胤
口試委員-王水進
口試委員-江孟學
口試委員-周榮泉
口試委員-李景松
中文關鍵字 超音波噴塗熱裂解  氧化銦錫鋅  可撓式薄膜電晶體  聚亞醯胺基板  氧化鋁  氧化釔  負閘極偏壓測試  負閘極照光偏壓測試 
英文關鍵字 Ultrasonic Spray Pyrolysis Deposition  Indium-Tin-Zinc-Oxide  flexible thin film transistor  polyimide substrate  aluminum oxide  yttrium oxide  negative bias stress  negative bias illumination stress 
學科別分類
中文摘要 本論文以超音波噴塗熱裂解法於可撓式基板上研製具有高介電係數介電層之氧化銦錫鋅薄膜電晶體,論文中探討在可撓式基板上使用氧化鋁跟氧化釔作為閘極介電層製作薄膜電晶體,在不同曲率半徑下彎曲,對於薄膜電晶體之電性影響。介電層與主動層皆使用超音波噴塗熱裂解法進行沉積,具備非真空、低成本、高沉積速率之優勢,並具有良好均勻度及高品質的薄膜。
我們選擇氧化銦錫鋅作為主動層,氧化銦錫鋅比起主流的氧化銦鎵鋅,擁有更高的遷移率和穩定性;由X-射線繞射分析確認,超音波噴塗熱裂解法沉積的氧化銦錫鋅薄膜具有c軸從優取向之結晶型,此結晶型比起多晶結構的晶粒邊界少,因此薄膜當中有較少的缺陷,能夠提升元件電性表現與穩定性,是極具發展潛力的材料。介電層部分選擇使用高介電常數材料,由於在高介電常數材料中,氧化鋁跟氧化釔具有製作成本低和較容易沉積的優點,因此我們選用氧化鋁跟氧化釔作為閘極介電層。
本研究當中,分別使用硬板(玻璃)跟軟板(聚醯亞胺)作為基板,並在同一基板上分別使用不同氧化層製作,並觀察與探討特性之影響。首先在玻璃基板上,各別沉積相同厚度的氧化鋁跟氧化釔做為薄膜電晶體中的氧化層,由於氧化釔比起氧化鋁具有較高的介電係數,並且有較高電容值,因此更容易聚集電子,擁有較高的驅動電流和較陡峭的次臨界擺幅。在線性區轉換特性有著開關電流比>107、次臨界擺幅109.3mV/dec、場效電子遷率28.4cm2/V-s和臨界電壓-0.1V。使用相同製程方式,將元件改製作在可撓式基板上,仍有類似於製作於玻璃基板上的特性表現。氧化釔與氧化銦錫鋅的搭配下,在線性區轉換特性有著開關電流比>107、次臨界擺幅110.7mV/dec、場效電子遷率27.2cm2/V-s和臨界電壓-0.45V的電性表現。並且在可撓式基板彎曲後,仍保有穩定的電性表現。
本實驗成功以超音波噴塗熱裂解法製備出可撓式薄膜電晶體,此沉積薄膜方法在製程時間以及成本皆相當具有優勢。無論是氧化鋁或是氧化釔作為氧化層並搭配氧化銦錫鋅製作成薄膜電晶體,氧化層跟主動層之間皆有良好的介面品質。但由於氧化釔的介電常數較高,使得元件電性表現方面擁有較高電子遷移率及高穩定性等優點,在下個世代平面顯示器產業需要更輕巧,柔軟和靈活的應用中極具潛力,可望在未來市面上被應用。
英文摘要 In this thesis, we fabricated ITZO thin-film transistors (TFTs) with high-k dielectrics on flexible substrate by Ultrasonic Spray Pyrolysis Deposition (USPD). Electrical characteristic of ITZO TFTs with the aluminum oxide and yttrium oxide as gate dielectrics on flexible substrate before and after bending. We deposited the ITZO channel layer and the Al2O3 dielectric layer by USPD. USPD has the advantages of non-vacuum, low cost, high deposition rates, and it also can deposit thin films with good uniformity and good quality.
In this work, ITZO has higher mobility and stability than IGZO. Grazing Incident X-ray Diffraction spectroscopy measurements were carried out and indicated that the ITZO thin film of C-axis-aligned crystalline (CAAC) structure. This structure compared with polycrystalline, there is no clear grain boundary which indicated CAAC-ITZO has lower density of defect states in the gap than polycrystalline. Therefore, TFTs with the CAAC-ITZO as an active layer have good electrical characteristics and reliability. In the dielectric layer, we choose high dielectric constant materials, which can enhance the control ability of devices. Aluminum oxide and yttrium oxide also have the advantages of low fabrication cost and high deposition rates. Therefore, aluminum oxide and yttrium oxide are used as the gate dielectric layer.
In this work, the characteristics of TFTs with different oxide layer were investigated. Furthermore, we did research into the difference of electrical characteristics between the flexible PI substrate and traditional glass substrate. First, the ITZO/Al2O3 TFT and ITZO/Y2O3 TFTs are fabricated with the same thickness on the glass substrate. The Y2O3 gate dielectric material has higher dielectric constant than Al2O3, so ITZO/Y2O3 TFT has higher capacitance at the same thickness. Therefore, ITZO/Y2O3 TFT is easier to accumulate electrons, and it has higher on-current and steeper subthreshold swing values than ITZO/Al2O3 TFT. In the linear region, the device exhibited higher on-current 4.51×10-4 A, higher μFE of 28.4 cm2/V-s, Ion/Ioff of >107, S.S. of 109.3 mV/dec, and Vth of -0.1V. Then, alumina oxide and yttrium oxide were used to fabricate TFTs on the PI substrate. The electrical performance of TFT on the flexible substrate is similar to the TFT on the glass substrate. In the linear region, the flexible ITZO/Y2O3 TFT has higher on-current 4.45×10-4 A, higher μFE of 27.2 cm2/V-s, Ion/Ioff of >107, S.S. of 110.7mV/dec, and Vth of -0.45V and it still has more stable electrical performance after bending.
In this study, the ITZO TFTs were successfully fabricated by USPD. The USPD method has considerable advantages of high deposited rate and low cost. The ITZO TFTs using Al2O3 or Y2O3 as oxide layer have good interface quality. In the electrical performance, flexible ITZO/Y2O3 TFT has the advantages of higher electron mobility and good stability. Therefore, ITZO TFTs become as an alternative choice for IGZO TFTs in the next-generation of the flat panel display industry which requires light-weight, soft, and flexible applications. The flexible ITZO TFT by USPD can exhibit great potential for bendable electronic/display equipment.
論文目次 摘要 i
Abstract iii
誌謝 vi
Content viii
Table Captions x
Figure Captions xii
Chapter 1 Introduction 1
1-1 Background and Motivation of Research 1
1-2 Ultrasonic Spray Pyrolysis Deposition 8
1-3 Organization 9
Chapter 2 Material Growth and Devices Fabrication 11
2-1 Device Structure and Fabrication 11
2-1-1 Pre-Cleaning 12
2-1-2 Gate Dielectric Layer 12
2-1-3 Active Layer 13
2-1-4 Source and Drain Electrodes 13
Chapter 3 Results and Discussion 16
3-1 Material Analysis 16
3-1-1 Grazing Incident X-ray Diffraction 16
3-1-2 Scanning Electron Microscopy 19
3-1-3 Ellipsometry 21
3-1-4 Photoluminescence Spectrometer 23
3-1-5 X-ray Photoelectron Spectroscopy 26
3-1-6 Atomic Force Microscopy 32
3-1-7 UV/VIS/NIR Spectrophotometer 36
3-2 DC Electric Characteristics 37
3-2-1 Capacitance voltage Measurement 39
3-2-2 On Glass Substrate 41
3-2-3 On Polyimide (PI) Substrate 45
3-2-4 Polyimide (PI) Substrate with bending 48
3-3 Stability 53
3-3-1 Negative Bias Stress 53
3-3-2 Negative Bias Illumination Stress 58
Chapter 4 Conclusion and Future work 63
4-1 Conclusion 63
4-2 Suggestion for Future Work 65
References 67
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