The School of Engineering at the Hong Kong University of Science and Technology (HKUST) has successfully developed the world's first deep ultraviolet microLED display array chip. This high-efficiency chip can be used with maskless ultraviolet lithography technology to improve the accuracy of its light output power density and promote the technological development of semiconductor chip production in a lower cost and faster way.
This research was guided by Professor Guo Haicheng, the founding director of the State Key Laboratory of Advanced Display and Optoelectronic Technology at USTC, and was conducted in collaboration with Southern University of Science and Technology and the Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences.
Photolithography machines are crucial equipment for manufacturing semiconductors. They utilize short-wavelength ultraviolet light to create different patterns, thereby producing various integrated circuit chips. However, this method of manufacturing using traditional mercury lamps and deep ultraviolet LED light sources has drawbacks, such as large device size, low resolution, high energy consumption, low luminous efficacy, and insufficient power density, which are detrimental to chip fabrication.
To address these challenges, the research team created a maskless development prototype platform, using it to fabricate the first microLED display array wafer produced by maskless exposure of deep ultraviolet microLEDs. This process improved ultraviolet light extraction efficiency, enhanced its heat distribution performance, and improved stress release during crystal epitaxy.
Professor Guo specifically mentioned, "The microLED display array chip developed by our team has achieved several key technological breakthroughs, including improved light source power and efficiency, pattern display resolution, enhanced display performance, and rapid exposure capabilities. This microLED display chip effectively integrates the ultraviolet light source and the pattern on the mask, rapidly providing sufficient irradiation dose for optical exposure of the photoresist, thus advancing the development of semiconductor manufacturing technology."
Professor Guo further pointed out: "In recent years, low-cost, high-precision maskless development technology has become an emerging R&D hotspot in the semiconductor industry. Because this technology can adjust the exposure pattern more flexibly, it provides more diverse customization options and saves the cost of manufacturing photomasks. Therefore, short-wavelength microLED technology, which helps improve the sensitivity of photoresist, is particularly crucial for the independent development of semiconductor equipment."
Dr. Feng Feng, a postdoctoral researcher in the Department of Electronic and Computer Engineering at HKUST, summarized: "Compared with other representative studies, we have achieved smaller device size, lower driving voltage, higher external quantum efficiency, higher optical power density, larger array size, and higher display resolution. These are all key performance improvements, and all indicators show that the results of this research are leading the world."
The paper, titled "High-Power AlGaN Deep-Ultraviolet Micro-Light-Emitting Diode Displays for Maskless Photolithography," was published in full in the top journal *Nature Photonics*. Since its publication, this research has gained widespread recognition in the industry and was selected as one of the top ten advances in China's third-generation semiconductor technology in 2024 at the 10th International Forum on Third-Generation Semiconductors.
Looking ahead to the next phase of research, the team plans to continue improving the performance of AlGaN deep ultraviolet microLEDs, refine the prototype, and develop high-resolution deep ultraviolet microLED displays ranging from 2k to 8k.
The first author of this study is Dr. Feng Feng, and the corresponding author is Zhaojun Liu, Visiting Associate Professor of the Department of Electronic and Computer Engineering at HKUST and Associate Professor at Southern University of Science and Technology. Team members also include Dr. Yibo Liu, a postdoctoral researcher in the Department of Electronic and Computer Engineering at HKUST, Dr. Ke Zhang, a PhD graduate, and researchers from various collaborating institutions.
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