Recently, Tianma’s Micro-LED production line has successfully completed the entire process.
As the next generation display technology, Micro-LED is hailed as the “hexagonal warrior” of the display family, featuring high brightness, high contrast, long lifespan, and low power consumption. Tianma has been focusing on Micro-LED technology since 2017, concentrating on high PPI, high brightness, and high transparency display technologies.
Transformation of Display Technology: From CRT to Micro-LED
In 1897, German physicist Karl Ferdinand Braun invented the cathode ray tube (CRT), which was the world’s first electronic display. For this invention, he received the Nobel Prize in Physics in 1909. In 1939, the first black-and-white television was produced in the United States. As technology matured, CRTs were widely used in televisions and computer monitors, with screens becoming larger and display effects improving, but they had drawbacks such as being bulky, size-limited, and immobile.
The invention of liquid crystal opened up a new field of display technology. In 1888, Austrian botanist Friedrich Reinitzer discovered a substance that changes between solid and liquid states with temperature, exhibiting liquid-like flow while showing optical anisotropy characteristic of crystals, known as “liquid crystal”.
In 1968, G.H. Heilmeier, working at RCA in the United States, invented a liquid crystal display device using a dynamic scattering mode, mainly used in watches, calculators, and pagers. In 1971, German scientist Helfrich and Swiss scientist Schadt invented twisted nematic liquid crystal displays, used in mobile phones, televisions, computers, and tablets. To increase display area, Hungarian scientist Brody later invented active matrix (AM) thin-film transistor (TFT) driven LCDs, opening the door to modern TFT LCD displays. TFT-LCD (thin-film transistor liquid crystal display) is widely used and is currently the most mature and complete mainstream display technology. Its display principle is based on controlling the arrangement of liquid crystal molecules using voltage, thereby altering the polarization of light to display images and text.
In 1987, Dr. Deng Qingyun invented OLED (Organic Light Emitting Diode), known as the “father of OLED”, marking the official debut of OLED technology. This is a self-emissive device with a multilayer organic film structure, and its biggest feature compared to liquid crystal is self-emission, eliminating the need for a backlight source. This characteristic brings many advantages: self-emission allows for better color gamut control and viewing angle control than LCD; due to the lack of polarization requirements for light paths, luminous efficiency is significantly improved, with faster response times, higher color gamut, and higher contrast; removing the backlight source effectively reduces thickness and weight; and current technology allows circuit boards to be coated on flexible films, making the entire OLED display flexible, which LCD cannot achieve. These performance advantages meet many emerging consumer demands, making OLED a rapidly developing next-generation display technology.
In recent years, Gallium Nitride (GaN)-based light-emitting diode display devices have been widely used in the development of next-generation display technologies. Among them, LED devices sized between 20~200μm are commonly referred to as Mini LEDs, while those below 50μm are called Micro-LEDs. (Note: Currently, there are different definitions for Mini LED and Micro LED chip sizes among various companies.) Mini LED displays are essentially still LCD displays but use smaller backlights, allowing for denser backlight arrangements, thus achieving higher brightness and finer local dimming. With the support of Mini LED backlight technology, the color gamut of LCD products is wider, and brightness and contrast are higher.
Micro-LED consists of a substrate layer, buffer layer, light-emitting structure layer, electrode layer, and packaging layer. By epitaxially growing the buffer layer and light-emitting structure layer on the substrate, epitaxial wafers are obtained, and through a series of micro-nano processes, positive and negative conductive electrode structures and light-emitting pixel structures are created to obtain Micro-LED matrix devices. The packaging layer typically serves to isolate electronic devices from water and oxygen environments and can mix phosphors, quantum dots, and other color conversion materials to correct the emitted color of the devices. Micro-LED inherits the high stability and high contrast advantages of traditional LED lighting while also possessing exceptional characteristics such as ultra-high resolution, ultra-high brightness, and tiny size, being hailed as the “key core” technology of the next generation display technology.
With technological advancements, semiconductor display technology is continuously upgraded, and new display technologies are emerging. The display technology landscape is dominated by LCD and flexible AMOLED displays, with emerging technologies like Mini LED and Micro LED flourishing. In recent years, the emerging Micro-LED technology features small chip sizes and self-emission characteristics, offering the advantages of OLED displays while outperforming in brightness, contrast, response speed, power consumption, lifespan, and flexibility, with a longer lifespan and better thermal stability.
Based on different application scenarios, the manufacturing of Micro-LED display devices can be divided into two major routes: mass transfer and single-chip integration.
Mass transfer involves separating microchips from the source substrate and picking them up in bulk, then transferring them individually or in groups to the corresponding pixel electrodes on the display substrate. This can be applied to display substrates of different sizes and materials. Due to industrial production requirements, mass transfer yields must not be less than 99.9999%, chip transfer errors must not exceed ±1.5μm, and transfer efficiency must be greater than 50~100M/h. Traditional chip transfer and packaging techniques cannot meet industrial demands, making mass transfer technology a bottleneck for the mass production of Micro-LED displays.
Single-chip integration refers to the bonding method, where chips from the source substrate are integrated onto the driver backplane at once. Although silicon-based Micro-LEDs based on single-chip integration technology perfectly avoid the problems of mass transfer, they currently can only display one color (currently, green LEDs have the highest luminous efficiency, with brightness reaching millions of nits), and they are only available in small sizes (there are industry proposals for quantum dot coloring solutions to achieve full-color display, but they face issues such as “severe blue backlight leakage” and “low integration yield of color pixels”). Due to their small size, they are currently limited to applications in near-eye displays (electronic viewfinders, VR/AR, etc.), smartwatches, and other high-resolution micro-display fields.
In response to the high precision and high efficiency mass transfer application needs for Micro-LED chips, various mass transfer technologies have been developed, including precise pick-and-transfer technology, self-aligned roller transfer technology, self-assembly transfer technology, and laser-assisted transfer technology. Among these, laser-assisted transfer technology utilizes the absorption of beam energy by material in the interface region to induce rapid physical changes or chemical reactions to generate driving forces to control the interface state. Under suitable process parameters, it can achieve high yield, precision, and transfer rates, becoming one of the most promising technical solutions for mass transfer of Micro-LEDs.
Domestic Micro-LED Industry Advances Towards Large-Scale Commercialization Dawn of Commercialization in Sight
Looking at the global development trend of new display technologies, the Chinese display industry has become a significant player after years of development. In the FPD (Flat Panel Display) market, Korean companies have gradually abandoned production and R&D, while Chinese companies have essentially won the LCD battle. Now, the display industry is shifting its focus to new display technologies to achieve differentiation and high profits.
In the past year, Micro-LED technology has made continuous progress, and related terminal applications and capital investments have accelerated the commercialization of this technology. With some Micro-LED projects gradually entering mass production, 2025 will be a crucial year for the commercialization of Micro-LED technology, with significant changes expected in terminal applications. Among them, domestic companies are no longer just followers; they are also participating in leading roles. Companies like Chenxian Optoelectronics, Tianma, Leyard, and Sitang Technology have successively launched, produced, and mass-produced Micro-LED projects, involving pilot lines and mass production lines for Micro-LEDs.
Sitang Technology: In June 2024, Sitang Technology will officially start production in a 20,000 square meter mass production factory in Xiamen, establishing a full-chain layout from chip design to mass production processes, with an annual production capacity of over 6 million sets for the Shenzhen pilot line and Xiamen mass production line.
TCL Huaxing: In October this year, the Micro-LED pilot line co-invested by TCL Huaxing and San’an has been completed, with small batch trial production expected in 2025.
BOE Huacan: On November 6, 2024, BOE Huacan’s 6-inch Micro-LED production line officially started production in Zhuhai. This project is the world’s first Micro-LED production line to achieve large-scale production, as well as the first 6-inch Micro-LED production line globally, with an annual production capacity of 24,000 6-inch Micro-LED wafers and 45,000,000 Micro-LED pixel devices once fully operational.
Leyard: On November 20, 2024, Leyard’s first fully self-developed new generation high-end MIP production line (Note: High-end MIP uses substrate-less Micro-LED chips smaller than 50μm, smaller than the chips used in previous MIP) officially went into production at the Wuxi Lijing factory. The first phase is expected to reach a production capacity of 1.2 billion units per month (Note: 1.2 billion means that this production line can produce 1.2 billion high-end MIP products each month), and the second phase will expand capacity to 2.4 billion units per month.
Chenxian Optoelectronics: On December 19, 2024, Chenxian Optoelectronics will activate a TFT-based Micro-LED mass production line in Chengdu with an investment of 3 billion yuan, featuring a fully automated intelligent production line covering transfer processes, backplane processes, and module processes, and will launch new products including a 135-inch Micro-LED splicing screen, a Micro-LED transparent splicing screen, and a Micro-LED light field naked-eye 3D screen.
Shenzhen Tianma: On December 30, the “Tianma New Display Technology Research Institute Micro-LED production line” successfully achieved full process connectivity, with plans for small batch production to begin in 2025. The module lit at the full process connectivity ceremony was the PID standard display unit module independently developed and produced by Tianma. This standard module is based on Tianma’s LTPS glass backplane and utilizes Tianma’s self-developed full-laser mass transfer technology, breaking traditional display size limitations, allowing for Micro-LED displays to be spliced together like “LEGO blocks”, achieving seamless splicing displays without size limitations.
As the scale grows, technology is also advancing. The Hubei Optics Valley Laboratory has collaborated with Huazhong University of Science and Technology to develop high-performance quantum dot photoresists, which are expected to bring breakthroughs to Micro-LED full-color display technology; a team from Hunan University, in collaboration with Norsight Technology and Jingneng Optoelectronics, developed an ultra-high brightness Micro-LED micro-display chip, achieving a single pixel brightness of up to 10 million nits on a highly uniform silicon substrate GaN epitaxial wafer.
Additionally, Xiamen University, Nanjing University, San’an Optoelectronics Co., Ltd., and Leyard Optoelectronics Co., Ltd. have signed a strategic cooperation agreement to officially establish the China Micro-LED Strategic Alliance, focusing on technological innovation needs, dedicated to building a shared mechanism for the industry chain, integrating development elements such as “production-research-application-finance”, forming a coordinated and supportive industrial ecosystem, and comprehensively enhancing the R&D and application levels of China’s Micro-LED display technology, accelerating the industrialization process.
(Source: Semiconductor Industry Overview. This article is produced by the Qingdao West Coast International Investment Promotion Center, reprinted for sharing and learning purposes only, not for commercial use. If there is any infringement, please contact for deletion.)
