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UBI Research、最新AMOLED工程を取り上げた「AMOLED Manufacturing Process」レポート発刊

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最近のスマートフォン市場ではフルスクリーンOLEDを採用したスマートフォン、プレミアムTV市場ではOLED TVが主流になっている。フルスクリーンOLEDとUHD解像度の大面積OLEDを実現するために以前とは異なる構造と工程が取り入れられたが、ディスプレイ関連メーカーがこのような情報を詳しく把握することは難しかった。

 

これに対し、今回UBI Researchは中小型と大面積AMOLEDの最新工程を分析した「AMOLED Manufacturing Process」レポートを発刊した。

 

本レポートではAMOLEDを中小型と大面積に分けて構造と工程を分析し、さらに中小型AMOLEDの検査工程も図表化したため、各メーカーはAMOLEDの構造全般と主要工程を把握できると期待される。

 

第1章では、中小型と大面積AMOLEDの基板からモジュールまでの全構造を取り上げた。第2章では、フレキシブルOLED用基板である二重PI（Polyimide）、TFT（LTPS方式とOxide方式）、OLED画素（蒸着方式とソリューションプロセス）、封止製造工程とセル、モジュール工程を順次分析した。第3章では、中小型AMOLEDの検査測定工程装置と主要装置について説明した。

 

また、第4章からはSamsung Displayにおける、9枚のマスクを用いたLTPS TFTのPad bending工程と13枚のマスクを用いたLTPS TFTのPad bending工程、LG Displayの大面積OLED用Oxide TFT工程を扱った。各工程に使用される装置と材料を分かりやすく分析し、最新TFT工程をより良く理解することができると期待される。

<アドオンタイプのリジッドOLED構造>

In-byeong Kang, CTO of LG Display, Discusses the Past, Present, and Future of Large Area OLED Panel

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On January 28, Korea Display Industry Association organized the 1st OLED Frontier Forum in JW Marriott Hotel Seoul.

 

Under the title ‘OLED, Yesterday, Today, and Tomorrow’, the forum attendees could review Korean OLED research results of the past 20 odd years, and discussed regarding future OLED industry growth strategy.

 

LG Display’s CTO In-byeong Kang gave a presentation on Large Area OLED Status and Future and talked about the current status and forecast of large area OLED which is expected to become the key area of future display.

 

Since the mass production of first 55 inch OLED panel that utilized WRGB method and oxide TFT, 3 years went past. During those 3 years, Kang revealed that many innovations were carried out in terms of TFT device, compensation algorithm, OLED device, OLED materials, and processes.

 

First, the oxide TFT structure changed to coplanar method from etch stopper method, and for compensation wiring, the internal compensation was changed to external compensation. Also, he revealed that through much effort, the existing OLED device and materials were changed to new structure and high efficiency and high color gamut OLED emitting materials. Kang added that the uniformity, which becomes the most crucial point in large area OLED panel mass production, was greatly improved in Gen8 manufacturing equipment.

 

In 2013, there was only 1 LG Electronics’ OLED TV, 55 inch FHD, but recently 77 inch and 65 inch were added, and the resolution increased to UHD. Kang emphasized that although the 2013 product was priced at 11 million KRW with 100/400 nit of brightness but recent products have brightness of 150/450 nit at the reduced price of 4.2 million KRW.

 

LG Display is going through many changes recently. OLED business department began operation from last year. Large area OLED panel, which started with 8K monthly mass production at Gen8, is now being produced at 26K in full operation. Also, additional investment of 10 trillion KRW to large area panel has been decided, and new factory is being built in Paju. Kang told the audience that he heard many positive views on large area OLED at CES, and that there was a huge response regarding the 77 inch HDR video. Kang revealed confidence in the technology reporting that rather than replacing LCD, OLED could succeed as a totally different display.

 

Regarding the next 20 years, Kang forecast that the flat will move toward transparent and flexible, and OLED is the most suitable for this. He explained that the Korean government estimated this and is carrying out national project titled ‘≥60 inch UHD level transparent flexible display and applicable IT fused infotainment system development’ for the past 4 years. LG Display is responsible for this project’s overall consortium, and is planning to reveal UHD level 60 inch transparent flexible OLED panel in 2017 summer when the project is complete.

 

At the end of the presentation, Kang summarized 3 innovation factors for large area OLED. First, the substrate materials at Gen8 has to change to PI and transparent PI. Second, even for flexible substrate, the structure has to change to top emission from bottom emission, and lastly, Kang added that much more diverse applications have to be considered for flexible panel.

 

엘지기사

[2015 OLED Evaluation Seminar] Oxide TFT Technology that 2015 should Spotlight

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By Hyun Jun Jang

 

During the 2015 OLED Evaluation Seminar (December 4) hosted by UBI Research, Professor Jin-Seong Park of Hanyang University gave a presentation titled OLED Oxide TFT Technology Trend, discussing oxide TFT, related industry, and technological issues as well as TFT technology that should receive the spotlight in 2016.

 

Oxide TFT has an advantage of high mobility and large area uniformity compared to a-Si TFT. As such, it is being more applied to large area OLED panel and used in LG Display’s OLED TV.

 

Park revealed that there are mainly 4 issues regarding oxide TFT and led with the reliability issue. Oxide TFT is essentially in amorphous state but when crystalized, the density and crystallizability increase; as oxygen does not move away and stay in place, defects occur less and reliability is high. Japan’s SEL and Sharp published CAAC (C-Axis Aligned Crystal) structure related oxide TFT paper, and Cornell University produced CAAC oxide TFT by increasing the substrate temperature and adjusting oxygen’s partial pressure.

 

The second issue is composition ratio. Park reported that composition ratio is the most closely related characteristic to TFT’s mobility. He revealed that recently research is being carried out centering around IGZO (indium gallium zinc oxide), but also oxide TFT research with different composition ratio is continually published. For example, ITZO (indium tin zinc oxide)’s mobility has been reported to reach 30cm/Vsec, and BOE is working on the related research. Research results, which showed increased mobility and reliability for IGZTO, which is IZTO with G added, was published, as well as ZnON (zinc oxide nitride) TFT’s 100cm/Vsec mobility. BOE demonstrated ZnO TFT applied 14.1inch AMOLED.

 

The third issue is the device structure. Park explained that efficiency can increase when top gate structure is used to oxide TFT as parasitic capacitor is not needed, but that the process is difficult. However, Park reported that JOLED revealed when self-alignment is used the number of masks used can be reduced and increases performance. This structure is applied to OLED TV by LG Display.

 

Lastly, Park gave the safety of device as the last issue. Oxide TFT can exhibit degradation effects from light, oxygen, hydrogen, and moisture. Park reported that hydrogen particularly has great effect on the safety. He explained that although the current prevailing OLED TFT is LTPS, as the panel becomes larger there will be technological competition between oxide and LTPS. Reporting that TFT which is cost efficient and shows high performance in diverse factors such as resolution will dominate the market, Park concluded his presentation.

 

 

 

박진성교수

[IMID 2015] LG Display Reveals Detailed OLED Plans

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During the keynote session of IMID 2015 (August 18 – 21), LG Display’s Sang Deog Yeo, the head of OLED division revealed LG Display’s intention to change the world with OLED together with everyone and strength in OLED industry expansion. Yeo explained that the most important factor in the success of large area OLED is strong conviction in OLED’s success and courage; he also announced further investment for OLED as future growth stimulus.

 

Yeo reported that TV’s first revolution was a change from black and white TV to color. The second revolution was the appearance of flat panel display and that the third revolution will be OLED. He explained that the key factors in TV panels are design and picture quality. He evaluated that these factors are advancing separately in other display while OLED is improving these issues together.

 

Explaining in more detail, Yeo reported that OLED has high design freedom as OLED structure is simple, a self-emitting light without BLU. Additionally, each pixel of OLED can operate independently and actualize true black, leading to differentiated picture quality.

 

In the beginning, LG Display struggled in applying WRGB technology and oxide TFT to OLED TV, which resulted in almost 0% of yield. Even within the company, there were opinions that oxide TFT application to Gen8 panel or larger will be almost impossible. However, the effort including introduction of external compensation circuit and coplanar structure, and compensation algorithm application to brightness and color brought LG Display’s current success of OLED TV mass production.

 

Yeo announced that much like how LG Display solved OLED TV’s technological problems of the past, they will improve the oxide TFT mobility to 50. He also revealed that LG Display is searching for a method of applying top-emission technology to mass production in order to improve transparent and flexible OLED technology, and researching light shutter technology and improved plastic substrate application technology.

 

LG Display recently announced their decision to invest approximately US$ 9,300 million centering around OLED. During the keynote session, Yeo reported that LG Display will increase the large area OLED panel’s production rate through investment, specifically from current 600 thousand units to 2 million units in 2017. He also announced that they will expand Gumi Gen6 line which will be used to increase production rate of small to medium-sized OLED panels and plastic OLED panels.

 

Although there has been speculation regarding this investment, through this keynote speech, it can be forecast the investment will be used in specific roadmap of large and small to medium-sized OLED. For the progress of OLED industry, which is growth stimulus of the future, Yeo emphasized the need for closer cooperation between materials, components, manufacturing equipment, and set companies, and laboratories and universities.

LG Display’s Sang Deog Yeo, IMID 2015

LG Display’s Sang Deog Yeo, IMID 2015