Scientists move closer to producing MicroLED displays faster and at lower cost
Scientists in Korea have employed a new technique known as fluidic self-assembly to speed up and reduce the cost of manufacturing MicroLED displays. Courtesy of Seoul National University
By Holly Chik
A team of scientists in Korea said they have developed an efficient method to manufacture MicroLED displays, driving toward cost-effective mass production of the next-generation display.
The researchers from Seoul National University (SNU) and LG Electronics said their new technique is a “strong candidate as an industrial solution” to produce large MicroLED displays, which had been complex and expensive to manufacture.
“Our results represent significant progress towards the ultimate goal of low-cost, high-throughput manufacture of full-color MicroLED displays by (the fluidic self-assembly technique),” they wrote in an article published in the peer-reviewed journal Nature on Thursday.
In 2021, Korea lost its top position in the global display sector to China, which held a 42.5 percent market share last year. In May, the Korean industry ministry said Samsung Display, LG Display and other Korean display companies will jointly invest more than 65 trillion won ($48.77 billion) in total by 2027 to secure innovative technologies and reclaim the leading spot.
The country aims to boost its global market share to more than 50 percent by 2027 from 37 percent last year by expanding organic light-emitting diode (OLED) display production lines and developing new technologies for next-generation display products.
MicroLED displays have gained attention as a future display due to their potential to outperform commonly purchased OLED displays in brightness, color saturation and durability, scientists of the latest study said.
First author Lee Dae-won, who conducted the study as a Ph.D. and postdoctoral research fellow at SNU said their technique could be used to build displays of smartphones, tablets, smartwatches and augmented reality devices as their research progresses.
He told The Korea Times that the product is likely five years away from going to market, depending on advances in manufacturing technology, scalability of the production process and market demand.
MicroLED displays are made up of arrays of microscopic particles, or chiplets, of inorganic light-emitting diodes (LEDs) that function as pixels. A 50-inch ultra-high definition display, for example, has more than 24 million chips, according to the study.
To manufacture them, tens of millions of LED chips with diameters small than a human hair are grown on thin slices of semiconductor material called wafers and then transferred onto a display substrate, or base material, the team said.
But conventional methods are slow. For example, it would take a robotic machine that picks up and places chips one by one 300 days to produce an ultra-high-definition MicroLED display, according to the study.
“Basic pick and place is time-consuming as it involves placing a single chip in a single spot. While placing multiple chips at once can speed up the process, it does not result in a significant reduction in the assembly time,” Lee said.
The fluidic self-assembly technique involves shaking to position and bond LED chips on a substrate. Courtesy of Seoul National University
The team, therefore, employed a technique known as fluidic self-assembly (FSA) to speed up the process. They assembled a two-inch blue light-emitting panel with more than 19,000 chiplets in 60 seconds during the study.
“Imagine you have a box filled with liquid and numerous small puzzle pieces floating around. When you shake the box, these pieces find their way into their designated slots, much like how our tiny LED chips find their spots on a substrate,” Lee said.
“The shaking motion in this case is equivalent to the external force used in FSA to position LED chips at specific locations on the substrate.
“Each spot on the substrate is designed to bond with an LED chip, and by carefully controlling the viscosity (thickness) of the liquid, we're able to accurately locate the LED chips to their spots. This results in a successful assembly rate of up to 99.9 percent,” he said.
Lee said that based on the FSA technology, LG Electronics is developing new transfer technologies that utilize other external forces, such as magnetism.