AMOLED 디스플레이의 박막트랜지스터 제작을 위한 결정화 기술 동향 및 대형화 연구

Trend of Crystallization Technology and Large Scale Research for Fabricating Thin Film Transistors of AMOLED Displays

Abstract

본 논문에서는 AMOLED 디스플레이 구동회로로 사용되는 박막트랜지스터의 구성요소 중에서 반도제 물질 제조의 최근 동향에 대해 논한다. 트랜지스터에 적용을 위해 특성이 좋은 반도체 막을 얻는 방법으로 비정질 실리콘을 다결정 실리콘으로 변화시켜야 하는데 레이저와 열처리 방법이 있으며, 레이저를 이용한 기술에는 SLS(Sequential Lateral Solidification), ELA(Excimer Laser Annealing), TDX(Thin-beam Directional Crystallization), 열처리 기술에는 SPC(Solid Phase Crystallization), SGS(Super Grain Silicon), MIC(Metal Induced Crystallization), FALC(Field Aided Lateral Crystallization)가 대표적이며, 이들에 대해 상세히 설명한다. 본 연구실에서 연구중인 레이저 결정화 기술의 대형 AMOLED 디스플레이 제작을 위한 연구 내용도 다룬다.

This paper discusses recent trends in the fabrication of semiconducting materials among the components of thin film transistors used in AMOLED display. In order to obtain a good semiconductor film, it is necessary to change the amorphous silicon into polycrystalline silicon. There are two ways to use laser and heat. Laser-based methods include sequential lateral solidification (SLS), excimer laser annealing (ELA), and thin-beam directional crystallization (TDX). Solid phase crystallization (SPC), super grain silicon (SGS), metal induced crystallization (MIC) and field aided lateral crystallization (FALC) were crystallized using heat. We will also study research for manufacturing large AMOLED displays.

Fig. 1. Images of (a) black and white, and (b) color CRT televisions.

Fig. 3. Structure of AMOLED displays composed of polariser, encap, organic layer, and TFT.

Fig. 5. Schematic diagrams of (a) amorphous and (b) polycrystalline silicon.

Fig. 6. Processes’ diagram for fabrication of poly-Si TFTs.

Fig. 7. Surface images of poly-Si layers after (a) SLS, (b) ELA, and (c) TDX processing.

Fig. 8. Surface images of poly-Si layers after (a) SPC, (b) MIC, (c) SGS, and (c) FALC processing.

Fig. 9. A schematic diagram showing scanning system and substrate holder inside the process chamber of nickel-sputtering system. Ions are discharged from the plasma which dislodges particles from the metal sputter target. The particles condense on the surface of the glass. The weight of the deposited nickel atom depend on the scanning speed and scanning time of nickel-target on the cathode.

Fig. 2. (a) LCD and (b) PDP televisions.

Fig. 4. (a) Loyol's FlexFai and (b) Samsung's Galaxy Fold.

Fig. 10. (a) Microscope image of long-lateral grains and (b) Brightness non-uniformity induced by oblique lines on SLS poly-Si AMOLED panel.

Fig. 11. (a) Full-color 5-inch AMOLED display shows a nonuniformity due to the different performance of TFT in the double scanned region. (b) Full-color 2.8-inch AMOLED display fabricated on the single and double scanned area for the excimer laser energy densities of 230 mJ/cm² on solid phase crystallized silicon films.

Fig. 12. (a) Basic concept of the RPL design and diagram of the pixel circuit (2 TFTs + 1 capacitor) connection of a simple one line RPL design. (b) The RPL designed panel (b) shows a uniform green image..