The setting sun's afterglow bathes the Xiamen Sea World, adjacent to the Xiamen Cruise Home Port, which looks like a commercial "giant ship".

"Micro-LED is the first time China has truly taken the lead in the field of display technology," said Zeng Yu, CEO of Xiamen Sitan Semiconductor, to the reporter of The Paper. In the field of optoelectronic display industry, China used to learn more from others in the past, but now, imperceptibly, it has reached the top of the global industry, transforming from a follower to a leader.

In 2022, the main research and design links of Sitan Technology were settled in Huli District, Xiamen. As the birthplace of Xiamen's special economic zone, Huli District has a cluster of optoelectronic industries, especially the new display industry with Micro-LED as the future direction, which is quite eye-catching. Xiamen City is the birthplace and industrial stronghold of China's LED industry, and it is also the only pilot city for the optoelectronic display industry cluster in the country. There are representative enterprises in epitaxial growth, chip manufacturing, and Micro-LED display panels.

Advertisement

As a new generation of display technology, Micro-LED uses micrometer-sized LEDs as light-emitting pixel units, featuring small chip size, high integration, and self-luminous characteristics. Compared with traditional display technologies such as LCD and OLED, it has obvious advantages in brightness, resolution, contrast, energy consumption, service life, response speed, and thermal stability, and is even considered the ultimate solution for future displays. As one of the earliest teams to conduct research on Micro-LED technology in the world, Liu Zhaojun, the founder of Sitan Technology, is one of the earliest researchers in the field of gallium nitride Micro-LED technology.

The difficulty of commercialization of Micro-LED lies in the high difficulty of mass production, and the yield rate determines the cost. In 2019, Sitan Technology built the first pilot line in the country, and achieved mass production at the end of June this year, becoming one of the few enterprises in the world capable of mass-producing Micro-LED.

Before the establishment of the special economic zone, Huli, located in the northwest of Xiamen, Fujian, was just a fishing village with a population of about 2,300. In October 1980, the State Council approved the establishment of the Xiamen Special Economic Zone on a 2.5 square kilometer plot of land in the Huli Agricultural Brigade of Xiamen City. Huli thus became the birthplace of Xiamen's special economic zone. In May 1984, the State Council decided to expand the scope of Xiamen's special economic zone to the entire island (including Gulangyu). Over the past 40 years, Huli has transformed from a small fishing village into a modern urban area, becoming a true portrayal of the rapid development of Xiamen's special economic zone and a vivid epitome of China's reform and opening up.

In 2023, the output value of the electronic information industry in Huli District approached 130 billion yuan, of which the output value of flat panel displays was about 73 billion yuan. As an important bearing area for Xiamen's optoelectronic display industry, the degree of industrial agglomeration is gradually increasing, with representative enterprises in the field of optoelectronic display such as Lingyang Huaxin, Xinying Display, Sitan Technology, and Chenghong, involving key links in the industry chain such as driver chip design, Micro-LED semiconductor display technology research and development, and touch screen and module manufacturing.

From LED lighting

The history of Xiamen's optoelectronic industry is long-standing. It can be traced back to Xiamen Bulb Factory, founded in 1958, which is also the predecessor of Xiamen Tongshida Co., Ltd. On July 1, 1958, Tongshida produced its first incandescent bulb, making Fujian Province have its own bulb production enterprise. Since then, enterprises such as Hualian Electronics and San'an Optoelectronics have gradually grown in Xiamen.

The foundation of the optoelectronic industry in Xiamen itself allowed the founder of Lida Xin to come into contact with this industry during international trade in the 1990s. In 2000, Lida Xin Import and Export Company was established. Just one year later, the first energy-saving lamp factory of Lida Xin came into being.In 2003, Xiamen City proactively cultivated three emerging industries: optoelectronics, software, biology and new medicine. In July 2003, the Semiconductor Lighting Research Group of the Ministry of Science and Technology came to Xiamen, which opened the curtain for the development of Xiamen's LED industry. This year, Xiamen began to pay a lot of attention and support to the LED industry. In June 2003, the "National Semiconductor Lighting Project" was launched. Three months later, Xiamen established the Xiamen Semiconductor Lighting Industrialization Base Coordination Group, led by the deputy mayor in charge of the municipal government. At that time, Xiamen was recognized as the city with the "earliest response, fastest response and most practical organization" in the national LED industry. The city formed a craze and atmosphere of "everyone knows optoelectronics and talks about LED everywhere". Xiamen attaches importance to and strongly supports the development of LED, which has become a consensus in the industry at home and abroad. Overseas companies and Taiwanese companies have come to Xiamen for inspection and cooperation. In 1993, Nobel Prize winner Nakamura Shuji and three other Japanese scientists invented blue light LED, making LED possible as ordinary lighting. The complete set of GaN LED processing technology developed by Shuji Nakamura and others at Nichia not only obtained blue LEDs based on wide bandgap materials that were previously difficult to obtain with other materials, but also opened the door to a series of direct bandgap semiconductor high-brightness LEDs. LED lighting has the advantages of energy saving, long life, strong color reproduction, and no flicker. As the technology gradually matures, Xiamen's lighting companies are gradually moving towards LED lighting. A breakthrough in technology and a reduction in costs have truly made LED semiconductor light emission usable as ordinary lighting. By stepping on these technical breakthroughs, a group of optoelectronic companies in Huli District, Xiamen, such as Lidaxin, have developed rapidly. However, achieving mass production is not easy. In 2008, Lidaxin entered the semiconductor lighting industry and achieved large-scale quantitative production in 2012. Since August 2011, with the approval of the Ministry of Commerce of the People's Republic of China, the Xiamen National Energy-Saving Lamps Foreign Trade Transformation and Upgrading Demonstration Base has been established with the energy-saving lamps industry in Huli District, Xiamen as the center, radiating the entire city. The base was later upgraded to the Xiamen National Foreign Trade Transformation and Upgrading Base (Energy-Saving Lamps). Xiamen was an early energy-saving lamp production base in China's lighting industry. After the emergence of LED, Xiamen became one of the regions with the fastest LED transformation. Data shows that from 2009 to 2016, the total number of optoelectronic enterprises in Xiamen increased from more than 150 to more than 300, and the total industrial output value increased from 40.6 billion yuan to 120 billion yuan, an increase of nearly 3 times; among them, the direct output value of LED lighting reached 32.3 billion, a year-on-year increase of 20%. Xiamen's LED epitaxial chip output and LED lighting exports have ranked first in China for many consecutive years. The total output of LED epitaxial chips accounts for more than 60% of the total domestic output; Xiamen occupies five seats in the top ten LED lighting export companies in the country. It is one of the world's largest high-end LED bulb manufacturing and export bases. For every 100 LED bulbs in the world, 30 are manufactured and exported by Xiamen. Compared with previous lighting equipment, the threshold for semiconductor production equipment is higher. From front-end chips to packaging and applications, the industrial chain is also more complex. How to produce efficient and reliable products involves multiple disciplines such as optics, electronics, structure, and engineering. Although it has paid a lot of price for exploration and running-in, Lidaxin finally mastered the core technology. Xu Jianxing, deputy general manager of Lidaxin Digital Education, told the reporter of The Paper that the company quickly became the "leader" in the LED lighting industry from an unknown small OEM factory of energy-saving lamps. This is related to the fact that the company has core technologies in its own hands and is more sensitive to environmental trends. Among LED lighting companies, Lidaxin is also one of the earliest companies to transform and deeply deploy the Internet of Things. Around 2015, Lidaxin continued to invest in research in the field of the Internet of Things, independently developed software in conjunction with production processes, and upgraded from a pure hardware manufacturer to a company with both hardware and software. Today, the product structure has expanded from lighting to security, control, home appliances and other fields. In terms of application scenarios, since 2014, it has extended from home lighting to campus eye protection lighting, and has taken the lead in the field of campus eye protection lighting. Make a good screen As LED lighting enters thousands of households, the market size continues to expand, giving rise to new applications, extending the display industry, and continuously extending to the high end of the value chain.Huang Kai, the Deputy Dean of the School of Physical Science and Technology at Xiamen University, told reporters from The Paper that at the end of the last century to the early 2000s, before the domestication, the price of an LED was 6 US dollars, and now the price of an LED is less than a cent. "Chinese people are particularly good at making something as cheap as cabbage." The characteristic of the semiconductor industry is that while costs are reduced, performance is generally steadily improved.

The opening of the general lighting market has driven the growth of the entire LED industry chain. At the beginning of the emergence of LED full-color display screens, due to the large spacing between the packaged light beads, the screen resolution was low, only suitable for large screen display and suitable for viewing from a distance, so it started to penetrate from outdoor large screen displays. With the reduction of LED costs and the continuous maturity of packaging technology, the volume of packaging devices has gradually decreased, and the spacing between pixel points has gradually decreased, and LED small pitch display screens have moved from outdoors to indoors.

The size of the LED chip is getting smaller and smaller, and the pixel density is getting higher and higher. In addition to the optoelectronic lighting industry, the optoelectronic display industry chain in Huli District of Xiamen is also continuously extending. Since 2000, companies such as TPK Technology, AU Optronics, and Qisda Display Technology have successively landed in Xiamen, gradually establishing an optoelectronic display industry cluster in Xiamen. Among them, TPK Technology, a leader in touch technology, landed in Xiamen Huli Information Optoelectronics Park in 2004, officially mass-produced multi-point projection capacitive touch screens in 2007, and applied them to the first generation of smartphones of internationally famous brands. Since then, it has started the touch revolution of human-computer interaction in the consumer electronics industry, and capacitive touch technology has gradually extended from mobile phones to more fields.

As a pioneer of capacitive touch technology, TPK has established R&D centers in Taiwan and Xiamen, giving full play to the advantages of industrial talents on both sides of the strait. TPK's vertically integrated production process has established a touch display module production line of 1-110 inches, and the core technology includes touch sensor technology, material design and development capabilities, high-precision full fitting technology, glass surface treatment technology, display open cell process and downstream system integration capabilities.

"We invest a lot of money in the development of touch technology every year, and we have more than 4,000 patents worldwide, covering touch panels, sensing electrodes, control circuits, protective covers, sensing electrode materials and their manufacturing methods, equipment and machinery, etc. These patents can not only keep us in the industry leader, but also well protect the rights and interests of customers and partners. Therefore, we have also won the honor of the national intellectual property demonstration unit." Dai Haichang, the senior manager of TPK's board office, told reporters from The Paper.

In order to meet the strict requirements for product quality, TPK has invested more than 100 million yuan to establish an advanced quality assurance laboratory, which was rated as "Xiamen City Touch Key Laboratory", including physical analysis laboratory, material laboratory, electrical laboratory, optical laboratory, environmental simulation laboratory, etc.

"We have obtained national laboratory certification in 2009 to ensure that we provide reliable and high-quality touch products to customers and end users. TPK has also actively shared the testing and analysis capabilities of the laboratory with the industry in recent years, promoting the high-quality development of the optoelectronic industry in Xiamen and even the South China region." Dai Haichang said.

With more than 20 years of accumulated manufacturing experience, TPK is also accelerating transformation, providing customers in the fields of electronic paper, additive manufacturing, automotive electronics, etc. with product development verification, production manufacturing and mass production solutions. In the field of electronic paper, TPK cooperates with the industry leader in cholesterol color liquid crystal electronic paper technology, and the product application covers electronic book readers, electronic tags, commercial displayers, electronic signs, etc. In the field of automotive electronics, it has launched a vehicle display assembly system; it has cooperated with the world's leading lidar technology company, becoming its exclusive mass production supplier for the next generation of vehicle lidar sensors.

"TPK's accumulated mass production manufacturing, product engineering design, and automation capabilities in touch can be expanded to more fields. In the future, TPK will not only be a professional touch technology manufacturer, but also an advanced manufacturing partner." Dai Haichang said.

Towards Micro-LEDRecently, the 0.13-inch microdisplay chip from Sitan Technology made its debut at the CES 2024 exhibition, becoming the highest PPI Micro-LED microdisplay released globally to date, and won the 2024 International Consumer Electronics Show (CES) Innovation Award.

In the industry, displays smaller than one inch are commonly referred to as microdisplays. Currently, Sitan Technology is the first in the world to achieve the research and development, pilot production, and mass production of microdisplays. Due to the high demand in the market, the production line operates 24 hours a day without interruption.

In 2022, the production capacity of display panels on the Chinese mainland accounted for about 60% of the global capacity, ranking first in the world in terms of production scale. In terms of scale, China has an advantage in the LCD market. In the OLED (AMOLED) field, the gap between China and South Korea is gradually narrowing. China has already had preliminary industrialization capabilities in Mini-LED, and the industrialization of Micro-LED is the next direction for breakthrough.

As the core of the next generation of display technology, Mini/Micro-LED has opened a new chapter in the development of the LED industry, with industry giants such as Huawei, Apple, Samsung, BOE, and TCL competing for layout. Optoelectronic semiconductor companies such as Shenzhen Tianma, Sanan Optoelectronics, and Qian Zhao Optoelectronics in Xiamen are also accelerating the transformation and upgrading to the new display industry and developing in the direction of Mini/Micro-LED.

In the era of LCD and OLED, many technologies were based on the industrial technology of Japan and Taiwan, China. In the field of Micro-LED, there is an opportunity to lead. The three founders of Sitan Technology all graduated from the Hong Kong University of Science and Technology, one of the "three major birthplaces of Micro-LED" in the world, and later engaged in display-related research at the Southern University of Science and Technology.

"Xiamen, as an international port city and one of the earliest special economic zones, attaches great importance to the construction and development of high-tech and hard technology. Entrepreneurs have a broad vision and are committed to creating a new industry chain with high barriers." said Zeng Yu.

After landing in Xiamen, Sitan Technology placed the design and research and development team of the driving chip and process route in the Huli District, and the mass production manufacturing in the Tong'an District. "Xiamen has an industrial chain advantage and determination in the layout of new display and semiconductors, which fits perfectly with the development vision of Sitan." said Zeng Yu.

The Sitan Technology mass production base located in Tong'an, Xiamen, has an annual production capacity of nearly ten million sets of Micro-LED display chips. (The picture is provided by the interviewee)

Since Apple acquired the Micro-LED technology company Luxvue in 2014, the pace of global innovative companies in the layout of Micro-LED has been accelerating. Sitan Technology has been focusing on this technology direction since 2006 and has been deeply involved for nearly 20 years. Years of technical accumulation have given it a first-mover advantage in this field of Micro-LED globally. "A leader is to bear the uncertainty of the future and the current situation without any reference cases."

Sitan cooperates with equipment manufacturers to jointly develop photolithography machines in the field of optoelectronic semiconductors, and produces optoelectronic chips and driving chips by itself. "We are using semiconductor processes to make displays, and the core is definitely our high-precision bonding integration, monolithic full-color and other core process technologies." Unlike the direction of continuously improving precision required by integrated circuit photolithography machines, the difficulty of Micro-LED photolithography machines lies in improving the optoelectronic conversion efficiency and durability during the production process. Because from the perspective of components, optoelectronic chips do not need to be so small, but they also have their unique needs. Optoelectronic chips are heteroepitaxial gallium nitride, while integrated circuits are homoepitaxial gallium nitride, and the epitaxial growth is also different, requiring quantum wells for energy conversion to emit light instead of storing computing power.To ensure the yield rate in mass production, it is essential to ensure the yield rates of both the optoelectronic chips and the driving chips, and the bonding process between the two is also a key factor in the yield rate. At present, Sitan Technology has accumulated nearly 800 intellectual property rights in the field of Micro-LED related technology. In terms of the massive transfer technology required for large-sized screens, they have also reserved patents.

The formation of new productive forces requires focus and accumulation. "Dr. Liu Zhaojun, as the founder and chairman of Sitan Technology, still serves as our technical director and has been engaged in technical research and development on the front line." The core team of scientists at Sitan is also a doctoral supervisor at universities. Through the connection between universities and enterprises, they have provided the enterprise with "seamless docking" talents who can directly commercialize scientific and technological achievements, and have established their own talent training mechanism.

Laying out the future

The optoelectronic display industry chain is relatively complex. It is difficult for a region to cover all links of the chain, and there is often a low matching degree between upstream and downstream enterprises in the industry chain, which relies more on collaborative cooperation between regions and even between countries.

From the perspective of the upstream, the structural materials include substrates, liquid crystal materials, organic luminescent materials, polarizing films, cover plates, etc., and the coating equipment includes vapor deposition machines, PVD, CVD, etc. Mini/Micro-LED requires massive transfer equipment and die bonding machines, etc. Production consumables include target materials, etching solutions, PI orientation solutions, special gases, photomasks, etc., and patterning equipment requires photolithography machines, dry etching machines, wet process equipment, etc. In addition, driving ICs, display chips, cell spacers, etc., are also very critical.

At present, the market for Micro-LED still needs to be cultivated. Industry insiders believe that many cutting-edge technologies in the display industry may take five to ten years from outbreak to truly mass civilian application.

As a leading company in the upstream driving chip design field, Lingyang Huaxin was established in 2017 and settled in Huli District, Xiamen City, continuing the R&D capabilities and experience from Taiwan Lingyang, focusing on driving chips for Mini/Micro-LED display and high-density dot matrix lighting applications.

Micro-LED has almost become a must-fight place for the future layout of various optoelectronic display companies. Xiamen Xinying Display Technology Co., Ltd., established in December 2020, is a company dedicated to the research and development of Micro-LED display technology, jointly created by TCL Huaxing Optoelectronics and Quanzhou San'an.

Different from Sitan Technology, which focuses on small and medium sizes, Xinying Display focuses more on the massive transfer, bonding, detection, and repair technologies required for Micro-LED based on TFT driving backplanes. The total investment of the project is 300 million yuan, committed to the research and development of new semiconductor display technology and the industrialization of Micro-LED display projects.

"The main purpose is to solve the intermediate links from chips to displays." Xie Xiangwei, deputy general manager of Xinying Display, told the reporter of The Paper that although the two shareholder companies have their own advantages in panels and chips, the massive transfer of Micro-LED is a new technology that neither of the two shareholder companies has, and the technology needs to be optimized, the yield rate needs to be improved, and the cost also needs to be reduced, which is not as easy as imagined.Micro-LED chips are small in size and high in precision. Each process, from chip supply to bonding, must undergo inspection and repair. Key parameters such as the uniformity and consistency of photoelectric parameters like chip brightness and wavelength, as well as the presence of any appearance defects, all need to be judged through inspection and determine what corresponding technical means to adopt for subsequent repair. Inspection and repair are another key technology to be conquered in Micro-LED display.

There has been a significant difference from the past use of LEDs for lighting to the current use of LEDs for display. Due to the extremely small size of Micro-LED chips, they cannot be transferred through traditional process technologies. In the past, there were many transfer technologies, but in the past two years, they have basically converged on using stamp transfer and laser transfer. The engineering process and the development of key node technologies in the laboratory are also very different.

"The goal is very clear, to aim for mass production. It is relatively easy to achieve research and development or pilot testing, but the issue of mass production engineering still needs some time to verify," said Xie Xiangwei. Reducing costs is very key, and each link must be carefully accounted for. Material costs, manufacturing costs, and professional management all need to be optimized. Efficiency and scale are also key to the success of engineering.

At present, the pilot verification line of Xinying Display has been basically completed, and it is planned to start pilot production at the end of this year, with the hope of expanding production to achieve mass production in the next 2 years.

"Every step is not easy, but it represents the future and is worth trying," said Xie Xiangwei.