Publications

Detailed Information

Improvement of Low Temperature Solution-processed Oxide Thin Film Transistors by O2 plasma, UV radiation and Biased-H2O annealing : O2 플라즈마, 자외선 조사, Biased-H2O 어닐링을 통한 저온 용액공정을 이용한 산화물 박막트랜지스터의 특성 향상에 대한 연구

DC Field Value Language
dc.contributor.advisor한민구-
dc.contributor.author이정수-
dc.date.accessioned2017-07-13T06:59:39Z-
dc.date.available2017-07-13T06:59:39Z-
dc.date.issued2013-08-
dc.identifier.other000000013275-
dc.identifier.urihttps://hdl.handle.net/10371/118936-
dc.description학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2013. 8. 한민구.-
dc.description.abstractZinc tin oxide (ZTO)나 indium gallium zinc oxide (IGZO)를 이용한 용액공정형 산화물 박막 트랜지스터는 고이동도, 빛 투명성, 플렉서블 적합성, 물질의 광범위함, 분자 구성비에 의한 전기적 특성 조절 용이성 등의 장점 때문에 실리콘 기반의 박막 트랜지스터와 유기물 박막 트랜지스터를 대체하며 능동 매트릭스형 디스플레이의 구동 소자로서 상당한 주목을 받고 있다. 용액공정형 산화물 박막 트랜지스터는 능동 매트릭스형 액정표시장치와 능동 매트릭스형 유기발광다이오드 디스플레이 백플레인으로서 많은 문제점을 가지고 있는 실리콘 기반의 박막 트랜지스터와 유기물 박막 트랜지스터와 비교하여 우수한 특성을 보여주고 있다. 더욱이, 용액공정형 산화물 박막 트랜지스터는 우수한 균일성과 고처리량 덕분에 대면적 공정에 적합하다.
ZnO 기반의 산화물 반도체 중에서, Sn 물질을 이용한 ZTO 박막 트랜지스터는 Sn이 널리 사용되고 있는 In 보다 상당히 저가의 물질이기 때문에 저가 공정을 확립하는데 유망한 소자이다.
추가적인 가격 절감과 플렉서블 디스플레이로의 응용성 확장을 위해서 용액공정형 ZTO 박막 트랜지스터는 저렴하고 플렉서블한 기판에 제작되어야 한다. 플렉서블한 기판은 고온에서 쉽게 손상되기 때문에 플렉서블한 기판에 용액공정형 ZTO 박막 트랜지스터가 제작되기 위해서는 저온 공정이 요구된다. 그러나, 저온에서 제작된 용액공정형 ZTO 박막 트랜지스터는 낮은 on-currnet, 높은 문턱 접압, 낮은 이동도 등의 열등한 특성을 가지므로, 우수한 특성의 용액공정형 ZTO 박막 트랜지스터를 제작하기 위해서는 500도 이상의 고온 공정이 필요하다. 저온에서 제작된 용액공정형 산화물 박막 트랜지스터의 소자 특성을 향상시키기 위해서는, 용액공정형 산화물 박막 트랜지스터에 대한 어닐링 온도의 영향성과 더불어 저온 공정에서 제작되더라도 우수한 소자 특성을 가지도록 하는 연구가 요구된다. 기존에 용액공정형 산화물 박막 트랜지스터에 대한 어닐링 온도의 영향상을 분석하려는 시도가 있었지만, 용액공정형 산화물 박막 트랜지스터에 대한 어닐링 온도 영향성의 전기적, 화학적 메커니즘은 거의 연구되지 않았다.
이 논문의 목적은 용액공정을 이용하여 다양한 어닐링 온도에서 산화물 박막 트랜지스터를 제작하여 문턱 전압, 포화 이동도, 신뢰성 등의 용액공정형 산화물 박막 트랜지스터의 전기적 특성에 대한 어닐링 온도의 영향성을 분석하고, 제안된 O2 플라즈마, 자외선 조사, Biased-H2O 어닐링 등의 방법을 통하여 능동 매트릭스형 디스플레이를 위한 저온 용액공정 산화물 박막 트랜지스터의 전기적 특성을 향상시키는 것이다.
-
dc.description.abstractSolution-processed oxide thin film transistors (TFTs) with zinc-tin-oxide (ZTO) and indium-gallium-zinc-oxide (IGZO) have attracted considerable attention for the driving elements of active matrix display, instead of Si-based TFTs and organic TFTs, because of high mobility, visible light transparency, flexibility, wide range of materials, and controllability of electrical properties by atomic composition. Solution-processed oxide TFTs show superior performance for active matrix liquid crystal display (AMLCD) and active matrix organic light emitting diode (AMOLED) display backplanes, compared with solution-processed Si and organic TFTs which have a number of issues. Furthermore, solution-processed oxide TFTs are compatible with large area due to good uniformity and high throughput, so that could be a method for achieving low cost fabrication contrary to vacuum processes.
Among various ZnO-based oxide semiconductors, ZTO TFTs employing tin (Sn) material maybe promising candidates for achieving low cost processes because Sn is a quite low cost material compared with widely used indium (In).
Solution-processed ZTO TFTs need to be fabricated on inexpensive and flexible substrates such as glass and plastic for additional cost reduction and application extension to a flexible display. For solution-processed ZTO TFTs fabrication with these flexible substrates, low temperature processes are necessary because these substrates are easily damaged at high annealing temperatures. At low annealing temperature, however, solution-processed ZTO TFTs have poor performance such as low on-current, high threshold voltage and low mobility, so a rather high annealing temperature exceeding 500 °C is required in solution-processed ZTO TFTs. To improve the device characteristics of solution-processed oxide TFTs even at low annealing temperature on an active layer, a study of the effects of annealing temperature on the electrical characteristics of solution-processed oxide TFTs and the efforts to achieve high device characteristics of solution-processed oxide TFTs even at low annealing temperature on active layer are desired. There were some efforts to investigate the effects of annealing temperature on solution-processed oxide TFTs, but the electrical and chemical mechanisms of annealing temperature on solution-processed oxide TFTs have been scarcely studied.
The purpose of this thesis is to fabricate oxide TFTs employing solution-process for an oxide semiconductor active layer with various annealing temperatures to investigate the effects of annealing temperature on the electrical characteristics of solution-processed oxide TFTs such as threshold voltage, saturation mobility, and reliability, and to improve the electrical characteristics of low temperature solution-processed oxide TFTs for low cost, stable, and flexible active matrix display backplane.
The effects of annealing temperature on the bonding structure of ZTO active layer in solution-processed ZTO TFTs were investigated and the chemical formation equation of the ZTO active layer with regard to the annealing temperature was established.
To improve the electrical characteristics of low temperature solution-processed oxide TFTs according to the investigation of effects of annealing temperature in regard of the chemical formation of ZTO active layer, O2 plasma treatment, UV radiation treatment, and the biased-H2O annealing were proposed to achieve high device characteristics of solution-processed oxide TFTs even at low annealing temperature. Moreover, the effects on electrical and chemical characteristics of solution-processed oxide TFTs with proposed methods were investigated in detail. These proposed methods to improve the electrical characteristics of low temperature solution-processed oxide TFTs would be suitable for the low cost, stable, and flexible active matrix display backplane.
-
dc.description.tableofcontentsAbstract i
Contents iv
List of Tables vii
List of Figures ix
Chapter 1 Introduction 1
1.1 Recent flat panel display technology 2
1.2 Device parameter extraction 12
1.3 Dissertation organization 14
Chapter 2 Review of solution-processed oxide TFTs 16
2.1 Overview of oxide TFTs 17
2.2 Advantages of solution-process 25
2.3 Solution-processed oxide TFTs 30
Chapter 3 Optimization of the fabrication process of solution-processed oxide TFTs 36
3.1 Overview 37
3.2 Structure of solution-processed oxide TFTs 38
3.3 Stirring time on solution-processed oxide TFTs 47
3.4 Active layer thickness on solution-processed oxide TFTs 56
3.5 Effects of passivation on solution-processed oxide TFTs 60
3.6 Electrical characteristics of solution-processed oxide TFTs 63
3.6.1 Transfer characteristics 63
3.6.2 Reliability characteristics 68
Chapter 4 Effects of Annealing Temperature on Solution-processed oxide TFTs 75
4.1 Motivation 76
4.2 Fabrication of solution-processed ZTO TFTs with various annealing temperature 78
4.3 Electrical characteristics with the increase in annealing temperature 80
4.4 Dechlorination on threshold voltage with the increase in annealing temperature 83
4.5 Dechlorination and crystallization on saturation mobility with the increase in annealing temperature 89
4.6 Reliability characteristics with the increase in annealing temperature 93
4.7 Chemical formation equations with the increase in annealing temperature 95
4.8 Conclusion 99
Chapter 5 Improvement of low temperature solution-processed oxide TFTs 100
5.1 Improvement of low temperature solution-processed oxide TFTs employing O2 plasma treatment 101
5.1.1 Motivation 101
5.1.2 Fabrication of solution-processed ZTO TFTs employing O2 plasma treatment 104
5.1.3 Electrical characteristics with O2 plasma treatment 108
5.1.4 Preferential dissociation of Cl on threshold voltage by O2 plasma treatment 111
5.1.5 Increase of electron concentration on saturation mobility by O2 plasma treatment 116
5.1.6 Reliability characteristics with O2 plasma treatment 119
5.1.7 Conclusion 122
5.2 Improvement of low temperature solution-processed oxide TFTs employing Ultra-Violet radiation treatment 123
5.2.1 Motivation 123
5.2.2 Fabrication of solution-processed ZTO TFTs employing UV radiation treatment 126
5.2.3 Electrical characteristics with UV radiation treatment 130
5.2.4 Effects of UV radiation treatment on oxide active layer semiconductors 133
5.2.5 Generation of hydroxide(-OH) bonding by UV radiation treatment on oxide active layer semiconductors 137
5.2.6 Conclusion 141
5.3 Improvement of low temperature solution-processed oxide TFTs employing biaed-H2O annealing 142
5.3.1 Motivation 142
5.3.2 Effects of various annealing condition 145
5.3.3 Effects of H2O wet annealing according to the annealing temperature 148
5.3.4 Proposed biased-H2O annealing to improve low temperature solution-processed oxide TFTs 154
5.3.5 Conclusion 161
Chapter 6 Summary 162
Bibliography 171
초 록 191
-
dc.formatapplication/pdf-
dc.format.extent6363242 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectOxide thin film transistor-
dc.subjectSolution-process-
dc.subjectAnnealing temperature-
dc.subjectO2 plasma-
dc.subjectUltra-Violet radiation-
dc.subjectBiased-H2O annealing-
dc.subject.ddc621-
dc.titleImprovement of Low Temperature Solution-processed Oxide Thin Film Transistors by O2 plasma, UV radiation and Biased-H2O annealing-
dc.title.alternativeO2 플라즈마, 자외선 조사, Biased-H2O 어닐링을 통한 저온 용액공정을 이용한 산화물 박막트랜지스터의 특성 향상에 대한 연구-
dc.typeThesis-
dc.contributor.AlternativeAuthorJeong-Soo Lee-
dc.description.degreeDoctor-
dc.citation.pagesxvi, 192-
dc.contributor.affiliation공과대학 전기·컴퓨터공학부-
dc.date.awarded2013-08-
Appears in Collections:
Files in This Item:

Altmetrics

Item View & Download Count

  • mendeley

Items in S-Space are protected by copyright, with all rights reserved, unless otherwise indicated.

Share