透明非晶態氧化銦鎵鋅薄膜電晶體研究與傳導機制建立

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國

立

交

通

大

學

顯示科技研

顯示科技研究所

究所

碩

士

論

文

透明非晶態氧化銦鎵鋅薄膜電晶體研究與傳導機制

建立

The study on channel thickness effects and transportation

mechanism establishment for InGaZnO Thin-Film-Transistors

研

究

生

生：

生

：

：傅治翔

傅治翔

指導教授

指導教授：

：

：劉柏村

劉柏村

教授

中

華

民

國

九

十

九

年

七

月

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透明非晶態氧化銦鎵鋅薄膜電晶體研究與

傳導機制建立

The study on channel thickness effects and transportation

mechanism establishment for InGaZnO Thin-Film-Transistors

研究生：傅治翔 Student：Chur-Shyang Fuh

指導教授：劉柏村 Advisor：Po-Tsun Liu

國立交通大學電機學院

顯示科技研究所

碩士論文

A Thesis

Submitted to the Display Institute

College of Electrical and Computer Engineering

National Chiao Tung University

in partial Fulfillment of the Requirements

for the Degree of Master

in

Display Institute

July 2010

Hsinchu, Taiwan, Republic of China

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透明非晶態氧化銦鎵鋅薄膜電晶體研究與

傳導機制建立

學生：傅治翔

指導教授：劉柏村

國立交通大學顯示科技研究所

摘

要

摘

要

摘

要

藉由探討氧通量，退火，不同製程因素使得氧含量對於銦鎵鋅氧薄膜的

特性影響，以提升非晶系銦鎵鋅氧薄膜電晶體的效能並藉由可靠度分析研

究，推導出非晶系銦鎵鋅氧薄膜電晶體的傳導機制。一開始，先藉由氧通

量的變化，來探討氧通量對薄膜特性的影響，而優化薄膜的半導體特性。

另一方面，藉由退火改善了半導體整層薄膜的膜質，結果隨著退火溫度增

高，臨界電壓會減小，其他電特性也隨之改善。進一步的，藉由引入不同

的退火情境，來探討不同退火氣體對於薄膜修補的影響，找出適合退火氣

體並且推導出銦鎵鋅氧薄膜電晶體傳導通道可分為前、後通道，而前通道

主要受退火溫度的影響而後通道的氧空缺可被退火氣體氧、氮所填補。接

下來，藉由探討真空、常壓環境下的可靠度分析，來探討外界環境對於非

晶系銦鎵鋅氧薄膜電晶體效能的影響，結果發現正、負的可靠度分析分別

受到外界氧氣、水氣的影響

_。

最後藉由改變不同非晶系銦鎵鋅氧薄膜厚度探

討前導通通道的厚度以及驗證可靠度分析的結果。

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The study on channel thickness effects and

transportation mechanism establishment for

InGaZnO Thin-Film-Transistors

Student：

：

：Chur-Shyang Fuh

Advisor：

：

：Dr. Po-Tsun Liu

：

Display Institute

National Chiao Tung University

ABSTRACT

The discussion of oxygen flux, annealing and the regulation factor causes

the different oxygen content in indium gallium zinc oxygen thin film to

promotes the a-IGZO TFT’s quality and because of the research of reliability

analysis, the transport mechanism have been derived in my thesis. In the

beginning, we discuss the affect of oxygen content in the film by changing the

oxygen flux and then optimize the semiconductor characteristic.

On the other

hand, we improved the semiconductor entire level thin film membrane by

annealing, the result advanced along with the annealing temperature, the

threshold voltage could reduce, other electricity characteristic also along with it

improvement.

Further, we discusses the different annealing gas regarding the

thin film patching influence in different annealing situation and discovers

suitable annealing gas to infer the a-IGZO TFT conduction channel to be

possible to divide into the front and back channel. The annealing temperature

mainly influence the front channel and the oxygen vacancy may fill up by the

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vacuum and atmospheric environment to discusses the external affect of the

a-IGZO TFT. The results generalize

the positive and negative reliability analysis

influences by the outside oxygen and moisture separately. Finally, by changing

the difference of indium gallium zinc oxygen film thickness to derive the front

channel thickness and prove the reliability results.

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誌

謝

誌

謝

誌

謝

誌

謝

首先要感謝指導教授劉柏村教授為我們建立了一個資源豐富的研究環

境，兩年的碩班生涯著實令我受益良多。除了設備完善讓我們可以有世界

級的研究成果，高水準的的師資與研究團隊可以隨時與世界頂尖研究成果

爭雄，實驗室注重英文能力等精神也讓我們不忘踏出關門研究的階段，培

養國際化的視野，成為更全方位的人才，可以在未來為校爭光，回饋培育

我們的社會。另一方面也感謝交映樓其他實驗室學長同學們的幫忙。

在實驗的過程中我最感謝我的好夥伴李富海、黃安迪、林敬儒、林俊傑、

鄭光廷。他們與我在無塵室內，量測機台邊共度無數時光。有漫漫長夜，

有破曉時分，擁有得來不易的令人欣慰的成果時，喜悅可以共享。也感謝

學長鄒一德、鄧立峯、竹立煒也不時給關心我們並給予指點並有情有義的

帶

_{著我們畢業。}

最後最重要的，我要感謝的父母傅玉華先生、于美珠小姐，他們的養育

之恩，栽培之情，與不離不棄的陪伴，比任何言語都要深刻而有力的支

持

_{著我，我會用一切的努力來報答。}

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Abstract (Chinese)……….iii

Abstract (English)………...……...iv

Acknowledgements……….………vi

Table of Content………....vii

Figure Captions………..……...x

Table Captions……….………....xiii

Chapter 1 Introduction………...……1

1.1. General Background………..….…..1

1.2. Amorphous Oxide Semiconductors………...……..2

1.2.1. The Introduction to Amorphous Oxide Semiconductors………..…...2

1.2.2. The Carrier Transport Mechanism of AOSs………3

1.2.3. Material about amorphous InGaZnO………..………..5

1.3. Motivation ………...7

1.4. Thesis Organization ………...9

Chapter 2 Experimental Procedures………...10

2.1. Experimental Procedures………...………...10

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2.3. Experimental flow

2.3.1. RF sputtering………...14

2.3.2. DC sputtering………...15

2.4. Electrical Measurement………...16

2.5. Parameter Extraction Method………...16

2.5.1. Determination of the Threshold Voltage………...17

2.5.2. Determination of the Subthreshold Swing………...17

2.5.3. Determination of the Field-Effect Mobility………..18

2.5.4. Determination of the On/Off Current Ratio………...19

Chapter 3 Experimental Results and Discussion………...21

3-1. The Effects of Oxygen Flow Rate and Post-Annealing on a-IGZO TFTs……....21

3.1.1. Introduction………...21

3.1.2. Results and Discussion………...23

3.1.2.1. The Effects of Oxygen Flow Rate on a-IGZO TFTs………...23

3.1.2.2. The temperature Effects of Post-Annealing on a-IGZO TFTs………..…………...28

3.1.2.3. The gas condition of Post-Annealing on a-IGZO TFTs………..30

3.1.3. Conclusion………...32

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3.2.1. Introduction………...33

3.2.2. Result and Discussion ………...35

3.2.2.1. Establish transport model on a-IGZO TFTs………...………..…………...35

3.2.2.2. The reliability analysis for a-IGZO TFTs………36

3.2.3. Conclusion ………...39

3-3. The Effects of IGZO film’s thickness on a-IGZO TFTs………..…...40

3.3.1. Introduction ………...40

3.3.2. Result and Discussion ………...40

3.3.2.1. The Effects of IGZO film thickness in a-IGZO TFTs ………..…………...40

3.3.2.2. The reliability of a-IGZO TFTs with different thickness of……….…...………...42

3.3.3. Conclusion ………...43

Chapter 4 Conclusion………...45

4-1. Conclusion………...45

4-2. Future Work………...46

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Figure Captions

Chapter1 Introduction

Fig.1-1 A photograph of the flexible TIFT sheet. The transparent TFT devices are made

visible by adjusting the angle of the illumination………..……….3

Fig.1-2 The schematic orbital drawing of electron pathway (conduction band bottom) in conventional silicon-base semiconductor and ionic oxide semiconductor……….…4

Fig.1-3 The optical transmission spectrum of the amorphous InGaZnO film……….6

Fig.1-4

LDA-relaxed a-IGZO structure containing………...……….7

Chapter2 Experimental Procedures

Fig.2-1

Experimental conception.……….11

Fig.2-2 (a)The staggered structure of a-InGaZnO TFT……….13

(b)The coplanar structure of a-InGaZnO TFT. ………13

Fig.2-3 Schematic sputtering system..………...14

Fig.2-4 Schematic RF sputtering system..……….15

Fig.2-5 Schematic DC sputtering system..………16

Chapter3 Experimental Results and Discussion

Fig.3-1 The carrier source of Metal oxide.………21

Fig.3-2 The oxygen vacancy(Vo) in IGZO film.………...22

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Fig.3-4 The deposition rate with oxygen flow rate.……...………24 Fig.3-5 The a-IGZO TFT ID-VG curve with different oxygen flow rates in (a) 250℃、(b) 350 ℃、(c) 450℃..……….25

Fig.3-6 Different oxygen flow rate (a) 0.2 sccm、(b) 0.6sccm、(c) 0.8sccm at different

annealing temperature.……….……….……….………...26

Fig.3-7 The (a)threshold voltage and (b) subthreshold swing at different annealing

temperature. .……….……….……….……….……….27

Fig.3-8 The ID-VG curve of a-IGZO TFT with annealing temperature from 250℃to 450 ℃………...28

Fig.3-9 The threshold voltage of a-IGZO TFT with annealing different temperature……..29 Fig.3-10 The Vth variation of a-IGZO TFTs after (a) positive gate bias stress (PGBS) and (b) negative gate bias stress (NGBS) with a electrical field of 1 MV/cm for 180 min………..…30

Fig.3-11 The ID-VG of a-IGZO TFT before and after being annealed in vacuum, oxygen and nitrogen environment at 450℃...……….……….………32

Fig.3-12 (a) Schematic of adsorption of oxygen molecules on a-IZO TFT backchannel

under application of +30 V gate bias stress. (b) Schematic reaction of water molecules on

a-IZO TFT backchannel under -30 V gate bias stress...……….………..34

Fig.3-13 The transportation model of a-IGZO TFT...……….………..36 Fig.3-14 The Vth variation of a-IGZO TFTs after positive gate bias stress (PGBS) and negative gate bias stress (NGBS) with a electrical field of 1 MV/cm for 180 min in atmosphere and vacuum….……….……….……….………37

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Fig.3-15 Schematic of adsorption position of O2 and H2O molecules on a-IGZO TFT

backchannel.……….……….……….……….………..38

Fig.3-15 The ID-VG curve with different IGZO thickness...……….……….41

Fig.3-16 The electrical parameters with different IGZO thickness...………42

Fig.3-17 The (a) PGBS and (b) NGBS with different IGZO thickness..………...43

Chapter4 Conclusion

Fig.4-1 The e-paper using oxide semiconductor TFT fabricated on flexible substrate…….47

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Table Captions

Table.2-1 The experimental flow path.……….……….………...11 Table.3-1 The deposition rate with different O2 flow rate..……….……….…24