For several years mass transfer of microLED’s has been amed as one of the most challenging process steps in microLED display manufacturing. Throughput, yield, flexibility, and small microLED handling must significantly improve to establish microLED’s in the display industry. The first attempts have been made and some pilot production lines and microLED displays are available today.

The key to industrial mass transfer is to provide a holistic solution that covers the fast and precise handling of donor wafers and receiver panels that could be backplanes or temporary carriers. Further, a package of diagnostics and software is required to enable and guarantee a high precise and high throughout transfer while using e.g. different levels of binning’s to compensate inhomogeneities from the EPI-wafer.

We will present our new turn-key system that is a breakthrough in industrial microLED display manufacturing with all the features nd benefits mentioned before.

We have developed an innovative and proprietary release stack that enables the rapid release of microcomponents with adaptive pitch and high selectivity using a low-cost laser source. Our technology demonstrates exceptional scalability and flexibility, allowing for the transfer of both mini- and microLEDs. In our R&D environment at Holst Centre, we achieved submicron transfer precision with a yield exceeding 99.9% on a sample set of over ten thousand microLEDs. This advancement is compatible with die-on-demand release from ultrahigh-density wafers, achieving edge-to-edge die spacing as small as just a few micrometers.

In addition to ultrasmall microcomponents, we have also applied our release concept to thin sub-mm components, such as Indium Phosphide (InP) coupons for integrated photonics. In our R&D environment, we demonstrated a transfer precision of less than 0.5 microns for InP coupons that are only a few micrometers thick, with aspect ratios of up to 10.

Ultrahigh-density and high accuracy integration of inorganic nano LEDs on a silicon represents great potential for realizing augmented and virtual reality (AR/VR) displays. High-accuracy electrofluidic assembly of InGaN-based blue-emitting nano-LEDs will be presented and discussed to address the technical limitations of OLEDoS and LEDoS technologies.

Fabrication of micro-LED displays with high yield and a minimal requirement for re-work is an important pre-condition for successful commercialisation of the technology. Economic production of micro-LED displays also requires the die size to be reduced to dimensions much smaller than has been used for mini-LED displays. This size reduction presents challenges in the attachment of the microscopic dies to active matrix driving systems.

Eutectic bonding of micro-LEDs to pads on the backplane commonly requires low melting point metals to be used such as indium or tin, with processing of these materials by difficult to scale processes of thermal evaporation and lift-off.

An alternative to eutectic bonding is presented here which reverses the fabrication process, starting with the micro-LED chip first where the anode/cathode pads of the flip-chip device are facing upwards. A planarization layer of organic polymer is formulated and coated on top of the die to provide a level surface and then patterned to form via holes over the pads. Metallization down the vias by sputtering then create ohmic contacts to the anode/cathode pads.

This process has been shown to have extremely high die light on yields due to the conventional via process used to make the connection. Active matrix driving of chip-first connected displays requires the use of TFT with low processing temperatures. This is due to the micro-LED sensitivity to elevated temperatures potentially caused by migration of metal atoms into the quantum well structures. Organic Thin-Film Transistors (OTFT) can be processed at 150°C and has been shown to be a suitable TFT technology for driving micro-LED. This presentation describes the potential for micro-LED device manufacturing using the chip-first approach and the types of display that OTFT may be suitable for in first-generation products.

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The choice of system architecture in AR glasses plays a pivotal role in shaping user experience, device form factor, power consumption, and overall performance. Most current designs rely on diffractive waveguide optics, which, despite their compactness, suffer from low optical efficiency. This inefficiency demands extremely high luminance from the microdisplay, often leading to the selection of technologies like LCoS (Liquid Crystal on Silicon) and microOLED. While these displays offer good image quality, they come with the drawback of high power consumption, necessitating larger batteries and thus increasing the overall size and weight of the device.
This creates a classic chicken-and-egg dilemma: efforts to reduce the size of the optical system inadvertently lead to bulkier and heavier overall designs. So far, many AR glasses have been developed through a technology-driven approach, aiming to integrate as many advanced features as possible. However, eyewear is subject to strict constraints in terms of weight and ergonomics. To truly optimize AR glasses, the design process must prioritize user experience and content delivery, placing these considerations at the core of the technical architecture to minimize system size and enhance wearability.
Ultimately, the ideal display technology for AR glasses depends heavily on the intended use case—whether for enterprise, consumer, or industrial applications. As the field evolves, we may see hybrid systems emerge that combine the strengths of multiple display types, enabling more seamless, efficient, and high-quality AR experiences.

In this presentation the challenges and current limitations within AR technology are discussed, particularly focusing on the challenges posed by display engines, such as lack of miniaturization and efficiency. We explore how Photonic Integration technology provides routes and solutions here. A platform is show that makes uses of flip-chipped bare laser diodes into a silicon-nitride based Photonic IC.

We describe the requirements for AR displays and describe how a laser illuminated holographic display technology can meet them. We present the basic operating principles of such a display realized by Swave’s HXR Nano-pixel SLM.

Designing OLED microdisplays for AR/VR applications presents a unique set of challenges, as each use case demands specific performance characteristics—ranging from low power consumption and high refresh rates to advanced eye-care features and consistent brightness stability. In this talk, we will showcase the latest achievements of our current micro-OLED products, highlighting how they address these diverse requirements. Additionally, we will offer a preview of our roadmap for next-generation VR micro-OLED displays, outlining the innovations and improvements we are pursuing to further enhance user experience in immersive environments.

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One of the intriguing yet largely unexplored technological approaches to fabricating microLED displays involves utilizing UV micro LEDs alongside colloidal quantum dots as light-converting materials. A main difference from traditional blue LEDs backlighting lies in the necessity of integrating hard-to-make and hard-to-get blue QDs in addition to red and green QDs. Despite this challenge, this approach offers several significant advantages, such as the lack of blue light leakage or better absorption efficiency of red and green QDs in the UV range as to name the most important ones.

In this presentation, we will show the properties of our UV curable inks, which are based on heavy metal-free, blue light-emitting QDs known as PureBlue.dots, which can be used for UV light conversion to high quality 455 nm blue light which can be used in microLED displays.
Furthermore, we will showcase our recent findings obtained from electroluminescent devices utilizing PureBlue.dots as the active material.

The miniaturization of LEDs has enabled their application in displays of various sizes, with Micro-LEDs emerging as a transformative technology in the field of micro-displays. Known for their high brightness, low power consumption, and exceptional reliability, Micro-LEDs are widely regarded as the optimal solution for AR/XR terminal devices. Early development of Micro-LED micro-displays built upon traditional LED manufacturing processes, utilizing sapphire and flip-chip solutions for low-resolution displays. However, these approaches faced significant limitations in meeting the stringent requirements of AR/XR applications, particularly due to challenges in GaN material growth and integration processes, which hindered the realization of single-chip full-color displays. Recent advancements in single-chip integration technology have paved the way for wafer-level full-color Micro-LED micro-display chips, positioning this technology as a leading candidate for future AR/XR systems.

A notable breakthrough in this field is the development of a 0.13-inch micro-display with a full-color resolution of 320×240 (Micro-LED resolution of 640×480) and color performance exceeding 100% of the DCI-P3 standard. This technology achieves a peak full-color brightness of 500,000 nits while maintaining low power consumption, with a single-chip full-color light engine volume of just 0.18cc, the smallest in its class. The architecture also demonstrates significant potential for further performance enhancements. Beyond display capabilities, this innovation represents a critical step toward mass production, leveraging quantum dot lithography as a highly feasible approach for full-color Micro-LED micro-display fabrication. The integration of versatile interfaces, such as MIPI and QSPI, ensures broad compatibility with diverse hardware systems, reducing development costs and accelerating adoption in AR/XR applications. These advancements underscore the potential of Micro-LED technology to redefine micro-displays for next-generation AR/XR devices.

This paper reports on the development of a specialized inkjet printing head and equipment for high resolution printing of QD dispersed inks. First, to achieve a robust process, we proposed an inkjet head design compatible with higher ink viscosity and with an ink circulation system to avoid particle aggregation. Further, we introduce a multi restrictor inside the head to minimize ink fluid pumping pulsations on the print head, and a drive-per-nozzle technology with individual nozzle waveform control. Results include down to 0.8pL+/-1.8% droplet variation across all nozzles, with 3sigama accuracy of 1.0um for droplet landing position. By combining optimized ink, inkjet head and equipment technology, we successfully fabricated color converter-type Micro LEDs display panels.

Hidehiro Yoshida's research interests include MEMS and NEMS technology, precision inkjet head, and precision stage for high-definition display panels. He received his M.E. and Ph.D. degrees in mechanical engineering from Nagoya and Tohoku Universities in 1995 and 1999, respectively. He joined Panasonic in 1995 and developed a power-assisted bicycle and an HD-DVD mastering system. From 2003 to 2004, he moved to the California Institute of Technology to understand the physics of nanotechnology. He received the Distinguished Paper Award in 2023 and 2024 at the SID International Symposium. And also received the Ichimura Industrial Prize in 2024. He is now expanding inkjet technology into various industries.

In the field of display repair, particularly for MicroLED technologies, there is a growing need for precise and scalable solutions to restore high-resolution defects without compromising performance. While several repair methods exist, they often fall short in resolution, versatility, or ease of integration. High Precision Capillary Printing (HPCaP) overcomes these limitations by leveraging capillary forces and mechanical resonance to deposit inks with micron and sub-micron precision, enabling accurate, reliable, and non-destructive repair of critical display components.

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