Polar Light Technologies, a leader in the development of microLED, is excited to announce a partnership with Finetech, a globally recognized supplier for sub-micron and high-accuracy die bonding solutions. The collaboration has already yielded significant advancements in micro-LED technologies for next generation AR, HUD and HMD applications.

Polar Light Technologies has introduced a major breakthrough in display technology by creating novel GaN pyramidal microLEDs that are directly bonded to Indium pads on a silicon chip. This new method, where LEDs are built from the bottom up, avoids the surface damage seen in traditional top-down methods, resulting in much better optical performance.

The special pyramidal shape of these LEDs allows for the creation of very small LEDs that are brighter and more efficient at emitting light by reducing energy losses and increasing their energy efficiency.

To connect these pyramidal microLEDs to silicon substrates, Polar Light Technologies teamed up with Finetech to develop a cold bonding technique that ensures accurate alignment with the electronics. In early trials, this method showed an impressive 85% success rate, proving its potential for large-scale manufacturing.

Pyramidal microLED to enable smaller, brighter and more efficient light emitters

Polar Light’s approach to making display front panels involves a bottom-up fabrication method using atomic layer regrowth. They grow GaN (Gallium Nitride) microLEDs in the shape of pyramids on a SiC (Silicon Carbide) substrate. This method produces high-quality microLEDs as small as 300 nm, without the damage caused by traditional top-down methods. As a result, the devices have near-perfect surfaces, which is crucial for optical properties.

These MicroLED displays can fit the resolution of a full TV screen into an area smaller than 5 mm², with about 1,000 by 1,000 connection points spaced just 5 µm apart. Polar Light’s design also significantly reduces energy use, making these microLEDs highly efficient for next-gen micro displays.

Compared to regular LEDs, the pyramidal microLEDs improve AR system efficiency by 50 to 200 times thanks to better internal and external quantum efficiencies and enhanced light utilization. By minimizing internal electric field interference and optimizing the interaction between charge carriers in the quantum wells, these microLEDs produce more light with sharper, more narrow emission. This makes them ideal for applications like augmented reality (AR) and micro-projectors, where precise light control is important.

Finetech develops cold compression bonding process for pyramidal microLEDs

A complete microLED display consists of three main parts: the front panel (the actual display), the back panel (which includes all the electronics), and the connection between the two. For the process of connecting the front panel to the back panel made of silicon, a modified flip-chip bonding method was used. In this process, the metallized GaN pyramids are precisely aligned and bonded to the Indium pads on the silicon back panel.

Because of differences in how silicon carbide and silicon expand with heat, no heat could be used during the bonding process. Finetech and Polar Light Technologies developed a cold compression bonding method for aligning and bonding MicroLED arrays using an automated FINEPLACER® femto 2 sub-micron die bonder. This machine ensures excellent process control, with high accuracy in flatness, alignment, and bonding force, which is crucial for connecting the fine-pitch Indium bumps for high-performance displays.

In addition to its precision, the FINEPLACER® die bonder is flexible enough to scale up production and adapt to new MicroLED technologies. Finetech also provides solutions for handling materials and cleaning with chemical or atmospheric plasma to avoid damage or contamination. This system allows for easy flipping of delicate Indium bump arrays without tweezers, and it ensures the materials are treated before bonding to improve overall quality.

Meet Polar Light Technologies and Finetech at MicroLEDConnect 2024

At MicroLEDConnect 2024 in Eindhoven on September 25-26, both companies present their latest innovations aimed at advancing microLED display technology.

Meet Finetech on booth #4, showcasing solutions that improve accuracy, reduce costs, and enable smooth scaling from research and development to large-scale microLED production.

Be sure to catch Finetech’s live session on Indium Bump Interconnect Flip Chip Bonding on Sep 26, 11:20 a.m. Learn how Finetech’s Indium Bump Interconnect technology is particularly beneficial for high-density flip-chip applications and can significantly enhance the reliability and efficiency of microLED devices.

TrendForce 2024 Micro LED Market Trend and Technology Cost Analysis
Release: 31 May / 30 November 2024
Language: Traditional Chinese / English
Format: PDF
Page: 160-180