臺灣博碩士論文加值系統

近年來，透明非晶態導電膜因具備高透光性與高電流驅動特性而受到矚目，其中銦基金屬氧化物是最被廣泛使用作為通道層的材料之一。
然而，由於銦的高成本和稀有的數量，使得我們勢必要研究出其他能替代的材料。在此，我們通過引入SnO2-ZnO雙通道層實現了高性能無銦金屬氧化物薄膜電晶體。在之前的文獻裡，發現SnO2-ZnO雙通道層會形成一種由三個區域組成的特殊結構，其中包含Zn-only、Zn-Sn-mixed以及Sn-rich區域，能使元件有更好的特性。
在本論文中，我們首先研究了ZnO厚度以及製程中O2:Ar的比例，試著探討對SnO2-ZnO雙主動層薄膜電晶體的影響。發現當在10 sccm O2通量下沉積3.6奈米厚的ZnO層時，該元件有最佳特性，最高的載子遷移率可達73 cm2 / V-s。我們還觀察到可以通過改變背通道層（ZnO）的厚度以及濺鍍時O2的通量來調變雙通道層薄膜電晶體的閾值電壓和載子遷移率。此外，我們發現HfLaO鈍化層的吸水特性對ZnO電晶體特性的保護起到很大的作用。

Transparent amorphous oxides are starting to emerge as a class of appealing semiconductor materials for application in electronics. Indium-based metal oxides are one of the most widely used materials as channel layers of metal oxide TFTs.
However, the need for developing indium-free metal oxide materials has grown urgent because of the high cost and limited supply of indium. Herein, we report high-performance indium-free metal oxide TFTs by introducing SnO2-ZnO dual active layer. From previous studies, the SnO2-ZnO bilayer channel structure form a unique nanostructure composed of three zones: Zn-only, Zn-Sn-mixed, and Sn-rich zones. The special combinational efforts in this structure resulted a high performance device.
In this thesis, we first investigated the effect of the ZnO thickness and the O2 flow in ZnO layer. The device exhibited the best characteristics when a 3.6nm ZnO layer under 10 sccm O2 flow was deposited. The resulting SnO2-ZnO TFTs exhibit outstanding mobility values as high as 73 cm2/V-s. We also observed that we could modulate the threshold voltage and mobility of bilayer channel TFTs by changing the thickness and O2 flow of the back channel layer (ZnO). Finally, we investigated that the HfLaO passivation can help maintain the performance of the ZnO TFTs because of its moisture absorption characteristic.

摘要.....................................................i
ABSTRACT................................................ii
致謝....................................................iv
Contents.................................................v
Table Captions.........................................vii
Figure Captions.......................................viii
Chapter 1 Introduction...................................1
1.1 General Background of Thin-Film Transistor (TFT).....1
1.2 Overview of Metal Oxide Semiconductor Thin Film Transistors..............................................3
1.3 Material properties of zinc oxide (ZnO)..............3
1.4 Material properties of tin oxide (SnO2)..............4
1.5 Overview of high-κ gate dielectrics..................5
1.6 Overview of HfLaO passivation layer on ZnO...........6
1.7 Motivation...........................................7
Chapter 2 Experimental Details..........................15
2.1 Device Fabrication of TFT...........................15
2.2 Process Flow of SnO2-ZnO active layer TFTs..........16
2.3 Methods of Device Parameter Extraction..............16
2.3.1 Determination of Threshold Voltage................16
2.3.2 Determination of Field-Effect Mobility............17
2.3.3 Determination of sub-threshold Swing..............18
2.4 Measurement Setup...................................18
Chapter 3 Experimental Results and Discussion...........23
3.1 Different thickness ZnO in bilayer channel TFTs.....23
3.2 Different O2 flow ZnO in bilayer channel TFTs.......32
3.3 The effect of HfLaO passivation layer on ZnO........41
Chapter 4 Conclusion....................................43
References..............................................44

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