Significance of MicroLEDs in Display Technologies

From LiDAR for autonomous vehicles to Mini and MicroLED displays, to the number of cameras increasing exponentially around us, to massive data centers requiring faster optical communications—optoelectronic devices are the future. Just as electrical technology eclipsed mechanical in impact and importance in the 20^thcentury, we will see optical eclipse electrical technology over the next 100 years. This continued progress brings new test challenges to ensure that optoelectronic devices are tested accurately, affordably, and quickly so that the latest display, car, camera, and data center enables new advances across our world.

One of the most notable test challenges occurs in testing optoelectronic devices at the semiconductor wafer and package level. Correlating and synchronizing both optical and electrical inputs and outputs is critical to producing high-quality optoelectronics quickly. At NI, we work with customers to test a variety of optoelectronic devices every day. While there are many differences in testing LEDs, optical transceivers, and laser diodes, these devices share a similar test challenge: how do we test both optical and electrical signals as quickly and efficiently as possible?

One prominent example of this test challenge is apparent in the emerging MicroLED technology for next-generation displays. MicroLEDs could be the next hot thing in display technology because they are so small that they can be used as individual pixels rather than the backlights that are common in LED displays today—MicroLEDs will provide better resolution and color depth over their traditional and MiniLED predecessors. While MiniLED backlit displays are only recently releasing into more mass-market consumer electronics, MicroLEDs are still extremely expensive—hundreds of thousands of dollars for a single display. To fully realize the benefits of MicroLED, costs across the entire supply chain (including test) must be lower.

We must test more LEDs at a time and test them faster. Hawk Lai, the CTO at FitTech (the leading LED wafer test machine builder), understands this challenge of reducing test time to reduce cost: “Mass testing of MicroLEDs is the critical challenge. To reduce test time and raise test efficiency, FitTech is building parallelized multi-site testing solutions. The goal is to test both optical and electrical characteristics of many MicroLEDs at the same time. This will reduce our test time while still getting reliable test data for every chip.” While efficiency improvements must be made across the entire supply chain, test is still important because MicroLEDs are so small (on the order of 10-50 um). If defective MicroLEDs are assembled into a display, the cost and complexity to repair or replace those LEDs are even greater.

To take advantage of MicroLEDs, our test methods must adapt to the technology. Increased parallelism with synchronized optical and electrical measurements is necessary to get the right insight into the health of optoelectronic devices. This means that optoelectronics manufacturers must consider not just the technology that they are creating but also how they will test that technology. They need to consider what test instruments and instrumentation platforms will help them scale to large channel counts for a MicroLED test, quickly acquire, and then synchronize optical and electrical measurements across all types of devices. If we can do this—test more affordably and faster— then not only will the future be optical, but we can start that future now.