Recently, TIANMA‘s Micro-LED production line has successfully completed its entire process flow.
As the next-generation display technology, Micro-LED is hailed as the “Swiss Army knife” of the display world, offering advantages like high brightness, high contrast ratio, long lifespan, and low power consumption. TIANMA began its focus on Micro-LED technology in 2017, emphasizing areas such as high PPI, high brightness, and high transparency displays. Now, the highly anticipated Micro-LED seems to be on the brink of commercialization.
I. The Evolution of Display Technology: From CRT to Micro-LED
In 1897, German physicist Karl Ferdinand Braun invented the cathode ray tube (CRT), the first electronic display in the world. For this invention, he was awarded the Nobel Prize in Physics in 1909. By 1939, the United States produced the first black-and-white television. As technology matured, CRT was widely adopted in television sets and computer monitors, with increasing screen sizes and improved display quality. However, it had notable drawbacks, including being bulky, size-limited, and not portable.
The invention of liquid crystals opened up a new era in display technology. In 1888, Austrian botanist Friedrich Reinitzer discovered a substance that shifted between solid and liquid states with temperature changes, exhibiting both fluidity and optical anisotropy, which he named “liquid crystal.”
In 1968, G.H. Heilmeier at RCA invented the dynamic scattering mode liquid crystal display (LCD) primarily for devices like watches, calculators, and pagers. By 1971, German scientist Helfrich and Swiss scientist Schadt invented the twisted nematic mode LCD, which was later applied to mobile phones, televisions, and computer screens. To expand the display area, Hungarian scientist Brody invented the active matrix (AM) thin-film transistor (TFT) LCD, opening the door to modern TFT LCDs, which became the most mature and widely used display technology today. The principle behind TFT-LCD involves controlling the alignment of liquid crystal molecules via voltage, thereby altering light polarization to display images and text.
In 1987, Dr. Deng Qingyun invented OLED (Organic Light-Emitting Diode), now known as the “father of OLED.” OLED is a self-lighting device made of multiple organic thin films. Unlike LCD, it does not require a backlight. This feature leads to advantages in color control, viewing angles, energy efficiency, response time, and contrast. The ability to coat OLED circuit boards on flexible films also allows for flexible displays, a feat LCD could not achieve. These benefits have made OLED a fast-growing next-generation display technology.
In recent years, gallium nitride (GaN)-based light-emitting diode (LED) display devices have been widely applied in the development of new-generation display technologies. Among them, Mini-LED refers to LED devices sized between 20 and 200 μm, and Micro-LED refers to those smaller than 50 μm. (Note: Companies may have varying definitions of Mini-LED and Micro-LED sizes.) Mini-LED displays still fundamentally use LCD technology but with smaller backlight units, allowing for more densely packed light sources and achieving higher brightness and finer local dimming. With the Mini-LED backlight, LCD displays benefit from a wider color gamut, higher brightness, and better contrast.
Micro-LED consists of several layers, including a substrate layer, buffer layer, light-emitting structure layer, electrode layer, and encapsulation layer. By epitaxially growing buffer and light-emitting structure layers on the substrate, followed by micro-nano processes to create conductive electrodes and pixel structures, Micro-LED matrices are fabricated. The encapsulation layer ensures isolation from water and oxygen, and can also incorporate materials like phosphors and quantum dots for color conversion, enhancing the display’s accuracy. Micro-LED inherits the advantages of traditional LED displays such as high stability and contrast, while also boasting features like ultra-high resolution, ultra-high brightness, and tiny size, making it a core technology for the next-generation display market.
With technological advancements, semiconductor display technologies are constantly evolving, leading to the emergence of new display technologies. The display industry now sees a vibrant mix of mainstream technologies like LCD, flexible AMOLED displays, and emerging technologies like Mini-LED and Micro-LED. The rise of Micro-LED technology, with its small chip sizes and self-lighting capabilities, combines the advantages of OLED while outperforming in brightness, contrast, response time, power consumption, lifespan, and flexibility. It offers even longer lifespans and better thermal stability.
II. Two Major Routes for Micro-LED
Depending on the application scenario, the manufacturing of Micro-LED devices can be divided into two main routes: mass transfer and monolithic integration.
Mass transfer involves separating microchips from their source substrates and batch-picking them before transferring them individually or in groups onto pixel electrodes of the display substrate. This approach is applicable to various sizes and materials of display substrates. However, industrial production demands a transfer yield of no less than 99.9999%, with chip transfer errors not exceeding ±1.5μm and transfer efficiency greater than 50-100M/h. Traditional chip transfer and packaging techniques cannot meet industrial requirements, making mass transfer technology a key bottleneck in the mass production of Micro-LED displays.
Monolithic integration bonds chips from the source substrate directly onto the driver backplane. While this approach sidesteps the mass transfer challenges, it is currently limited to displaying only one color (with green LED offering the highest efficiency and brightness reaching up to one million nits) and is constrained to small sizes. Solutions like quantum dot colorization have been proposed to enable full-color displays but face challenges like “significant blue light leakage” and “low yield of colored pixel integration.” Because of the small size, this technology is currently used mainly in near-eye displays (such as viewfinders and VR/AR devices) and high-resolution microdisplays like smartwatches.
To meet the need for high-precision and high-efficiency mass transfer of Micro-LED chips, various technologies such as precise pick-and-place transfer, self-aligned roller transfer, self-assembly transfer, and laser-assisted transfer have been developed. Among these, laser-assisted transfer uses energy from light beams to induce physical or chemical changes at the interface, overcoming the adhesion forces between the surface materials and the Micro-LED. With the right process parameters, this technique can achieve high yield, precision, and transfer speed, making it one of the most promising solutions for mass transfer of Micro-LED devices.
III. The Rapid Growth of Domestic Micro-LED Industry and the Dawn of Large-Scale Commercialization
The global display industry has witnessed remarkable progress, with China emerging as a significant player after years of development. In the FPD (Flat Panel Display) market, South Korean companies have gradually stepped back from production and R&D, while Chinese firms have largely won the battle for LCD. Now, the focus of the display industry has shifted to emerging display technologies, aiming for differentiation and higher profits.
Over the past year, Micro-LED technology has made continuous strides, with related terminal applications and capital investments accelerating the commercialization process. With some Micro-LED projects moving into mass production, 2025 is set to be a pivotal year for the commercialization of Micro-LED technology, with even greater breakthroughs in terminal applications. Among these developments, domestic companies are no longer merely following; they have stepped into the lead. Companies such as VISTAR, TIANMA, LEYARD, and SiTan Tech have launched, produced, and mass-produced their Micro-LED projects, including Micro-LED pilot lines and mass production lines.
SiTan Tech: Expanding into Full-Chain Production
In June 2024, SiTan Tech officially launched its mass production factory in Xiamen, covering approximately 20,000 square meters. The company has established a full-chain layout from chip design to mass production processes, with an annual production capacity exceeding 600 million sets between its Shenzhen pilot line and Xiamen mass production line.
TCL CSOT: Progressing Towards Small-Batch Production
In October of this year, TCL CSOT and San’an Optoelectronics‘ joint venture, Xinying Display, completed its Micro-LED pilot line. The company expects to begin small-scale trial production in 2025.
BOE HC SemiTek: The World’s First 6-Inch Micro-LED Production Line
On November 6, 2024, BOE HC SemiTek‘s 6-inch Micro-LED mass production line officially began operations in Zhuhai. This is the world’s first mass production line for 6-inch Micro-LED displays. Upon full production, it will have an annual output of 24,000 wafer groups (6-inch), as well as 45 billion Micro-LED pixel devices.
LEYARD: High-End MIP Production Line for Micro-LED
On November 20, 2024, LEYARD launched the first phase of its next-generation high-end MIP production line at its Wuxi Lijing factory. The line is capable of producing 1.2 billion high-end MIP units per month. The second phase will expand the capacity to 2.4 billion units per month.
VISTAR: Advancing with TFT-Based Micro-LED Production
On December 19, 2024, VISTAR unveiled its TFT-based Micro-LED mass production line in Chengdu, backed by an investment of 3 billion yuan ($420 million USD). The line incorporates transfer process, backplane process, and module process automation. The company also introduced new products such as the 135-inch Micro-LED Splicing Screen and Micro-LED transparent splicing screen.
TIANMA: Full-Process Micro-LED Production Line in Operation
On December 30, 2024, TIANMA successfully completed the full-process integration of its Micro-LED production line at its New Display Technology Research Institute. The company plans to begin small-scale production in 2025. The line’s integration ceremony showcased a PID standard display unit module developed by TIANMA, which uses LTPS-based glass backplane and laser mass transfer technology to break traditional display size limits, allowing for seamless, borderless Micro-LED displays.
Technological Advancements and Collaborations
Alongside the growth of the industry, technology is also advancing. Hubei Optics Valley Laboratory, in collaboration with Huazhong University of Science and Technology, has developed a high-performance quantum dot photolithography material, potentially leading to breakthroughs in Micro-LED full-color display technology. A team from Hunan University, together with Innovision and LatticePower, has developed an ultra-bright Micro-LED microdisplay chip, achieving 10 million nits brightness on silicon-based GaN epitaxial substrates with high uniformity.
In addition, Xiamen University, Nanjing University, San’an Optoelectronics, and LEYARD have signed a strategic partnership agreement to form the China Micro-LED Strategic Alliance. The alliance aims to drive innovation by integrating the elements of industry, academia, research, application, and capital, building a coordinated ecosystem that will accelerate the commercialization of Micro-LED technologies in China.
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