MicroLED are progressing on all fronts. Investments and intellectual property activity are increasing and many prototypes from large corporations and startups alike have been presented over the last 12 months. But as discussed extensively in Yole Développement’s new MicroLED Displays report, the industry hasn’t yet crossed the finish line and many technology roadblocks remain.
Mikro Mesa Technology (Mikro Mesa) was established in 2014 by display industry veteran Li-Yi Chen, former vice president of LCD panel maker China Star Optoelectronics Technology (CSOT), a subsidiary of TCL. After initially remaining relatively quiet about its progresses, Mikro Mesa recently announced some breakthrough in its transfer and assembly technology as well as a partnership with Chinese panel maker CEC Panda.
Yole Développement (Yole) display analysts, Eric Virey and Zine Bouhamri talked with Stefan Chen, CSO at Mikro Mesa, about the company’s technology, strategy and prospect for microLED displays. Discover below the details of their discussion.
Eric Virey (EV): Could you please introduce yourself, Mikro Mesa and your role at the company?
Stefan Chen (SC): Mikro Mesa is dedicated to μLED tehnology, who offers the design and whole process of micro LED manufacturing. We were established in 2014 by Dr. Li-Yi Chen and our company already developed an effective microLED solution. I am the Chief Strategy Officer of Mikro Mesa offering the industrial insight to our company and searching for opportunities for our partners.
EV: What are Mikro Mesa’s strengths and key elements of differentiation? What are the specificities of your transfer technology and die architecture?
SC: A unique point is that most of our team members came from the display industry. This gives us an advantage to think about how to make a good display and how to construct effective process steps. Our process operates below 200 Celsius degree and without pressure treatment. Those factors make the process easier. I also think we are one of the very few who can provide a solution for transferring 2-5μm chips and capable to produce multi-color display.
EV: You are using fairly large transfer stamps. What are the benefits and what kind of challenges does this create?
SC: Large stamps save a lot of tact time and manufacturing cost. The structure of our stamps is simple and robust. We hope such kind of design can assist the microLED industry in reaching massive production scale of square kilometer area per month. In other words, a scale similar to that of current LCD fabs. When using large stamps, the major challenge is to make full contact with the receiving backplane on such large area when the stamp is putting chips on the substrate. It is not done easily by our handmade machine now, but we believe it can be solved via better design on the transfer equipment in the future. By the way, if we can inspect chips on temporary carrier carefully, large stamps will be very powerful.
Zine Bouhmari (ZB): Which applications are Mikro Mesa targeting?
SC: We may do wearable devices and TV first. If we can make good microLED displays for wearable application and TV, that means it is not far away from making the display for mobile phones.
ZB: The microLED intellectual property landscape is increasingly crowded and complex. What is the status of Mikro-Mesa. Do you think the industry will need to mutualize some IP through cross licensing?
SC: Our company owns 36 granted U.S patents and 18 patents in other countries. There are also more than 100 pending patents worldwide. The major coverage areas of our portfolio are mass-transfer, inspection and driving system. I believe now is too early to talk about IP cross licensing because there is no consensus on which production concept is the best to produce microLED displays. For example, the big difference between flip-chip and vertical structure implies very different approach. Thus the overlap of each company’s IP is not big enough yet.
ZB: Could you elaborate more on your partnership with CEC Panda? What is the history of the relationship? What is each party bringing to the collaboration?
SC: We helped our partner build a laboratory which can verify the feasibility of microLED technology. This laboratory also has the ability to make display samples using 3~5μm chips. Panda contacted us in 2017 and they offered a laboratory space, facilities and equipment. We helped them learn our microLED technology. After constructing the lab, we took another 8 months to verify our process and made the samples. I think this case is a good co-work example to fulfill both parties.
ZB: CEC Panda already has a fairly mature oxide TFT technology (note: the company has long been collaborating on the topic with Sharp, the first company to bring the metal oxide TFT to volume manufacturing). Do you think IGZO will deliver sufficient performance to drive microLED displays? Is power consumption an obstacle?
SC: IGZO is a good candidate for driving microLED, especially in large size TV. However, to convert the conventional IGZO TFT from a switching device to a current regulation device is not so easy. We need to consider the bias stress and threshold voltage shift. It involves some new TFT structure development and design. Even though, I believe that IGZO is still a good backplane for microLED above 10”. Power consumption is another issue because a TFT consumes a lot of energy when it plays a current regulation device. However, the power consumption of microLED TV will be much smaller than white OLED TV which is already in the market. After our evaluation of the current OLED panel, we think the power consumption of microLED will not be an obstacle, but it is worthy to improve it in the future.
EV: What role and positioning in the supply chain are you anticipating for Mikro Mesa? What is your business model? Will you be involved in manufacturing or focus on developing and licensing enabling technologies?
SC: In this stage, we are quite flexible because I believe our potential partners have different purposes. Our rich experience in display industry will help us meet our partners’ needs. For example, we may help our partner build up their own pilot line and co-work to mass production with specific products. Or we can collaborate with our partner to build a factory including TFT and microLED. We of course provide licensing as well. Our integrated display knowledge can make our partner reach their target faster. After that, eventually, we will have our own products which are not in the scope of conventional displays.
EV: What do you see as the major remaining challenges for microLED volume manufacturing? As an industry, do you think most of the major technology blocks have been removed? Is it now mostly about optimizing costs and yields and setting up the supply chain or are there still major technological challenges?
SC: Originally, we though mass transferring the chips below 10μm was the major challenge. Now we have solved it and have confidence in handling 3μm chips. This means the obstacle of material cost is eliminated. Now the red wavelength chip becomes the major remaining challenge for microLED. If we downsize the chip to 2-5μm, the AlGaInP chips will cause an efficiency problem. They are also more brittle than GaN chips. However, there is some good progress on red InGaN material and it will benefit microLED display a lot. Besides the red chips, most of the major technology blocks seems to be removed. The next question is when will the first consumer product adopt microLED display. Once a leading company starts to use microLED, then the all display supply chain will get involved in optimizing cost and yields. I believe it will happen within 2 years.
EV: When can we expect to see the first microLED TV?
SC: Optimistically, consumer grade TV can be realized in 2021.
About the interviewee
Stefan Chen is Chief Strategy Officer of Mikro Mesa. Stefan has 17 years experience in TFT LCD industry including R&D, Product Manager, Business Marketing, and also an executive in this industry. He has developed comprehensive perspective in analyzing the technology and market of μLED, and focus on its commercialization and applications. Stefan got his Master Degree of Engineering in National Taiwan University.
About the interviewers
Eric Virey, PhD serves as Principal Display Market and Technologies Analyst at Yole Développement (Yole), within the Photonic & Sensing & Display division. Eric is a daily contributor to the development of LED, OLED, and Displays activities, with a large collection of market and technology reports as well as multiple custom consulting projects. Thanks to its deep technical knowledge and industrial expertise, Eric has spoken in more than 30 industry conferences worldwide over the last 5 years. He has been interviewed and quoted by leading media over the world. Previously Eric has held various R&D, engineering, manufacturing and business development positions with Fortune 500 Company Saint-Gobain in France and the United States. Eric Virey holds a PhD in Optoelectronics from the National Polytechnic Institute of Grenoble.
As a Technology & Market Analyst, Displays, Zine Bouhamri, PhD is a member of the Photonics, Sensing & Display division at Yole Développement (Yole).
Zine manages the day to day production of technology & market reports, as well as custom consulting projects. He is also deeply involved in the business development of the Displays unit activities at Yole.
Previously, Zine was in charge of numerous R&D programs at Aledia. During more than three years, he developed strong technical expertise as well as a detailed understanding of the display industry.
Zine is author and co-author of several papers and patents.
Zine Bouhamri holds an Electronics Engineering Degree from the National Polytechnic Institute of Grenoble (France), one from the Politecnico di Torino (Italy), and a Ph.D. in RF & Optoelectronics from Grenoble University (France).
Emerging Technologies 2020
January 14-15, 2020 – Shanghai, China
Eric Virey will participate to this powerful event with a dedicated presentation:
“Next generations TV technologies: how could microLED, QD and improved LCD challenge OLED”
Significant progress over the last 18 months, but many challenges remain before ramping up for large volume consumer applications.