Title

Breaking the Performance-Stability Trade-off in Dual-Gate a-IGZO TFTs via Single-Step Laser Annealing for Capacitor-less DRAM

Alternative Title

단일 레이저 열처리 공정을 통한 이중 게이트 비정질 인듐-갈륨-아연 산화물 박막 트랜지스터의 성능–안정성 트레이드오프 극복 및 커패시터리스 디램 응용

DGIST Authors

Sihyeon Kwon ; Hyuk-Jun Kwon ; Byeongmoon Lee

Advisor

권혁준

Co-Advisor(s)

Byeongmoon Lee

Issued Date

2026

Awarded Date

2026-02-01

Type

Thesis

Description

DRAM, Dual-gate TFT, laser annealing, IGZO, amorphous oxide semiconductors

Table Of Contents

List of Contents

Abstract i
List of contents iii
List of tables v
List of figures vi

Ⅰ. INTRODUCTION
1.1 DRAM Scaling and Structural Limitations 1
1.2 Amorphous Oxide Semiconductors (AOSs) 3
1.2.1 Defects: Oxygen Vacancies and Hydrogen Impurities 3
1.2.2 Carrier Transport Mechanisms 4
1.3 Characteristics of 2T0C DRAM Cells 6
1.3.1 Operating Principles of 2T0C DRAM 7
1.3.2 Operating Principles of Advanced 2T0C DRAM 10
1.4 Laser Annealing Process 11
1.4.1 Characteristics of Laser Annealing 12
II. EXPERIMENTAL DETAIL
2.1 Fabrication & Electrical Measurements 15
2.2 Laser System Set Up 17
III. RESULT AND DISCUSSION
3.1 Optimization of Dual-gate a-IGZO TFTs 19
3.1.1 Source/Drain materials optimization 20
3.1.2 Top-gate dielectric optimization 21
3.1.3 Effect of Top-Gate Overlap Regions 26
3.2 Laser Annealing Process on Dual-Gate a-IGZO TFTs 28
3.2.1 Film Composition and Chemical States Change 30
3.2.1.1 Channel region 30
3.2.1.2 Contact region 37
3.2.2 Simultaneous Enhancement of Drivability and Vth Stability 44
3.2.2.1 Positive Vth Shift and µFE Improvement 44
3.2.2.2 Contact Resistance Reduction 53
3.2.3 Electrical Stability of DG a-IGZO TFTs 58
3.2.3.1 Positive/Negative Bias Stress (PBS/NBS) Test 58
3.2.3.2 Underlying Mechanisms of Enhanced Stability 61
3.3 Read Operation Reliability for 2T0C DRAM Applications 64
IV. CONCLUSION

URI

https://scholar.dgist.ac.kr/handle/20.500.11750/59699
http://dgist.dcollection.net/common/orgView/200000943562

DOI

10.22677/THESIS.200000943562

Degree

Master

Department

Department of Electrical Engineering and Computer Science

Publisher

DGIST

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