Micro LED offers advantages in brightness, contrast, refresh rate, power consumption, and form factor, and is well matched to optical waveguide technology. It is regarded as the ultimate solution for AR near-eye display applications. Micro LED not only inherits Micro OLED’s strengths—high resolution, high PPI, high refresh rate, and high contrast—but also retains the characteristics of inorganic LEDs, enabling further improvements in response time, power consumption, and color gamut, while effectively addressing Micro OLED’s shortcomings in brightness and lifetime.
Technical Challenge: Full-Color Rendering as the Core Bottleneck Requiring Industry Breakthroughs
Overall, the primary challenges in fabricating Micro LED microdisplays lie in substrate preparation, chip architecture, bonding processes, and full-color display. Among these, full-color rendering is the core difficulty and urgently requires industry-wide breakthroughs. Current full-color Micro LED approaches include color-combining optics, quantum-dot (QD) color conversion, three-color vertical stacking, and monolithic direct epitaxy.
Display architectures must be matched with optical systems, with Micro LED emerging as the ultimate partner for waveguides. Current microdisplay options include LCOS, DLP, LBS, Micro OLED, and Micro LED. Because different optical paths impose different brightness requirements, pairing a suitable optical solution with a suitable microdisplay can yield synergistic performance (>1+1). At present, the “Micro OLED + BirdBath” configuration has become a rapid, pragmatic option balancing cost and image quality, accelerating adoption of consumer-grade AR glasses.
However, because the likely mainstream optical path—optical waveguides—exhibits very low optical efficiency, Micro OLED struggles to deliver sufficient in-eye brightness. By contrast, Micro LED offers advantages across brightness, contrast, refresh rate, power consumption, and volume, making it well suited to waveguides and widely regarded as the ultimate solution for AR near-eye displays. In recent years, the number of AR glasses adopting a “waveguide + Micro LED” configuration has increased year by year.
1. Micro LED: A “Hexagonal Warrior” in Display Technology with Advantages Across Dimensions
Micro LED refers to LED miniaturization and matrixing. It thins, miniaturizes, and arrays the LED structure so that pixel units are reduced below 100 μm (P0.1) while enabling per-pixel addressing and emission control. Micro LED shares Micro OLED’s attributes—high resolution, high PPI, high refresh rate, and high contrast—while leveraging inorganic LED traits to further improve response time, power consumption, and color gamut, effectively mitigating Micro OLED’s low brightness and short lifetime. Despite these strengths, Micro LED still faces challenges in yield, process complexity, and manufacturing cost.
Micro LED product forms are evolving along two major trajectories: (1) medium- to large-format displays with low pixel density (low PPI), for wearables, large TVs, or signage; and (2) microdisplays with high pixel density (high PPI) for AR/VR/MR. This document focuses on high-PPI Micro LED for AR glasses.
2.Technical Challenges: Full-Color Rendering as the Core Difficulty Requiring Industry Breakthroughs
High-PPI Micro LED microdisplays typically adopt a monolithic semiconductor integration route: the display wafer is directly bonded to a CMOS backplane, the epitaxial substrate is subsequently removed, and a Micro LED array is fabricated on the CMOS backplane using semiconductor processes before being diced to the required display size.
This route uses semiconductor processing end-to-end, with critical pixel dimensions defined by photolithography, enabling smaller pixel sizes and tighter pixel pitch. It also eliminates secondary mass transfer, achieving ultra-high pixel counts and ultra-high resolution in a single step. The main challenges lie in substrate preparation, chip architecture, bonding, and full-color display.
2.1 Substrate Preparation: Miniaturization Imposes Higher Demands on Epitaxial Substrates
Key issues include wavelength uniformity, defect control, and sidewall damage.
• Wavelength uniformity: Micro LED is self-emissive. In high-resolution applications, nonuniform emission wavelength leads to significant color shift and degraded image quality. To ensure display performance, the within-wafer wavelength standard deviation must be ≤0.8 nm. As substrate size increases, wavelength uniformity becomes harder to control during epitaxy, making gas-flow and temperature uniformity in MOCVD growth especially critical.
• Defect control: At miniature scales, Micro LEDs are more sensitive to defects. Substrate defects can include particles, contaminants, scratches, and pits introduced by epitaxy, processing environment, or equipment. For example, a ~2×2 μm defect on a 250×250 μm LED chip leaves the usable emission area largely unaffected; the same ~2×2 μm defect on a 5×5 μm Micro LED greatly reduces usable area to only 84%. To maintain yield, defect density should be controlled below 0.1/cm².
• Sidewall damage: Etch-induced sidewall damage reduces the usable emission area. A ~2 μm sidewall-damage region on a 250×250 μm LED chip still leaves ~97% usable area; on a 5×5 μm Micro LED, usable area drops dramatically to ~4%.
Common Micro LED substrates include sapphire, silicon, and SiC. Sapphire is lower cost; silicon offers low cost, large area, high quality, and good electrical/thermal conductivity with improved uniformity. However, GaN on these substrates is heteroepitaxial, introducing lattice and thermal mismatch with the GaN epilayer, which increases dislocation density and degrades optical efficiency.
Using GaN as a native substrate can markedly improve epilayer crystalline quality, reduce dislocation density, extend device lifetime, and support higher operating current densities. However, GaN single-crystal substrates are extremely difficult and costly to fabricate, and are limited to ≤4-inch diameter, constraining commercial scalability.
2.2 Chip Architecture: Vertical Structure Enables Further Pixel Shrink
Micro LED chip structures include flip-chip and vertical:
• Flip-chip: Anode and cathode are on the same side, on mesas of p-GaN and n-GaN. With no electrode shading of the emission aperture, the emitting area is large. However, same-side electrodes can induce mesa-level current crowding, affecting uniformity.
• Vertical: The native sapphire substrate is typically removed, and the device is transferred to a higher-thermal-conductivity substrate, improving heat dissipation and device stability. After laser lift-off of sapphire exposes the n-GaN, the n-electrode is formed. With electrodes on opposite faces, current distribution is more uniform, supporting higher peak current density and higher optical power density. The architecture also enables further size reduction, favoring high-PPI microdisplays. Vertical Micro LED chips are widely regarded as the development trend, but their processing is more complex, costs remain high, and mass-production capability still needs improvement.
2.3 Bonding Process: Wafer-Level Monolithic Hybrid Integration Enables Scalable Production
Die to Die
Traditional chip-level (flip-chip) bonding fabricates the Micro LED array and the silicon driver IC on separate substrates with matching geometries, then singulates the Micro LED wafer, deposits indium bumps on the driver wafer, and uses high-precision alignment to flip-chip bond individual Micro LED dies onto the CMOS driver. Challenges include: (1) Alignment accuracy—chip-level processes require very high bonding precision, impeding mass production and cost reduction; (2) Wafer bowing—thermal mismatch between heterogeneous substrates and epilayers causes wafer curvature, impacting yield and reliability; (3) Indium recess/voids—at reflow temperatures, indium can alloy with gold, diffusing into the underlying Au electrode and forming recesses/voids.
Wafer to Wafer
Wafer-level hybrid integration follows standard semiconductor processing: the entire epitaxial wafer is bonded to the CMOS backplane at wafer scale, then the epitaxial substrate is removed (e.g., by laser lift-off or wet etch), and the Micro LED array is fabricated on the CMOS backplane. Pixel size is set by photolithographic precision and can be reduced to the nanometer regime. This approach relaxes alignment requirements, eliminates indium pillars or solder for interconnect, allows vertical chip structures, further shrinks pixel dimensions, and increases pixel density. Leveraging semiconductor processes enables lower-cost, high-throughput production and economies of scale.
2.4 Full-Color Display: Color-Combining Is Relatively Mature; Monolithic Full Color Is Accelerating
Current full-color routes include color-combining optics, quantum-dot (QD) color conversion, three-color vertical stacking, and monolithic direct epitaxy. Color-combining is comparatively mature, though module volume still needs further reduction. Three-color stacking and monolithic epitaxy are more challenging and largely at the laboratory stage.
Color-combining optics
A trichroic prism (X-cube) optically combines RGB Micro LED into full color (often termed a “light-engine” approach). Red, green, and blue Micro LED arrays are packaged on three submounts, connected to a control board and trichroic prism. By prism refraction and per-channel brightness control, color mixing and imaging are achieved. Advantages include high image quality, saturated color, high brightness, and low power. Challenges include red-emitter efficiency, wavelength uniformity, optical path control, thermal management, and device lifetime. JBD currently supports mass production of full-color Micro LED via color-combining.
Quantum-dot color conversion
Two structures are typical: (1) blue Micro LED excitation with red and green QDs; (2) UV Micro LED excitation with integrated red/green/blue QDs. QD layers are patterned into high-PPI arrays via photolithography or inkjet printing. Challenges include QD coating precision, conversion efficiency, optical crosstalk, and QD stability, with conversion efficiency being the most difficult. Nonetheless, QD conversion is the simplest laboratory route to monolithic full-color Micro LED. Vendors pursuing QD color conversion for Micro LED microdisplays include Leiyu Technology and Sitan Technology, with current outputs mainly demos or small-batch samples.
Three-color vertical stacking
Three vertically stacked RGB wafers form a single pixel, enabling full color. Compared with lateral RGB sub-pixels, vertical stacking reduces per-pixel footprint, enabling higher pixel density for small-format, high-resolution microdisplays. However, this route imposes very high demands on epitaxy, bonding, electrode design, and color optimization; most devices remain at lab/demo stage.
3.Vendor Landscape: Active Deployment Across the Industry, with JBD Leading in Technical Capability
3.1 JBD
Founded in 2015, Shanghai Jade Bird Display (JBD) focuses on Micro LED microdisplay R&D and innovation, spanning backplane design, MOCVD epitaxy, Micro LED panel fabrication and packaging/test, and hardware/software driver design. Its ultra-miniature displays serve AR glasses, automotive HUD, micro-projection, and 3D printing.
Product portfolio: AM-µLED microdisplays, AM-µLED light engines, AM-µLED optical modules and related development kits, and AR near-eye waveguide picture-quality correction (ARTCs).
Technical breakthroughs: diversified full-color solutions with sustained brightness gains. (1) X-cube route: In 2023 JBD released the first consumer-grade full-color AR light engine “Hummingbird I.” In 2024, luminous flux increased from 3 lm to 6 lm; combined with a waveguide module, in-eye brightness improved from 2,000+ nits to 6,000 nits. (2) Vertically stacked monolithic full color: In 2023 JBD unveiled the world’s first 0.22-inch 2K monolithic full-color vertically stacked Micro LED microdisplay prototype, the Phoenix series, with 5 μm RGB composite pixel pitch and <5 μm stack thickness, supporting a 50° field of view. By end-2024, brightness reached 2 million nits, with mass production expected in 25Q3. In addition, Micro LED brightness continues to rise: green has surpassed 10 million nits, while red and blue have reached 1.5 million and 2 million nits, respectively.
Capacity: Phase-1 of JBD’s Hefei Micro LED microdisplay line was completed in October 2023, supporting monthly shipments of several hundred thousand microdisplays. Once fully built out, it targets annual capacity of 120 million Micro LED microdisplays, substantially strengthening JBD’s supply capability.
Adoption: According to JBD’s WeChat posts, by end-2024, more than 30 lightweight AR glasses models based on JBD Micro LED had been announced, including StarV Air2 (Xingji Meizu), Rokid Glasses, INMO GO2, Vuzix Z100, OPPO Air Glass 3, and others.
3.2 Leiyu Optoelectronics
Founded in 2019, Leiyu Optoelectronics focuses on high-performance, mass-producible full-color Micro LED microdisplays. Leveraging a re-architected monolithic integration flow with a proprietary common-anode (CoANODE) ultra-high-brightness Micro LED chip architecture, large-area GaN-on-Si epitaxy, and QD full-color technology, Leiyu is among the first to realize AR-grade monolithic full-color Micro LED microdisplays.
Products: In October 2022, Leiyu successfully lit a 0.39-inch monolithic full-color Micro LED microdisplay; in May 2023 it announced 0.11-inch and 0.22-inch monolithic full-color series. The 0.11-inch device set a then-record for minimum full-color microdisplay size, weighing only 0.23 g with 320×240 resolution. In September 2024, Leiyu released the mass-production-oriented PowerMatch® 1 full-color Micro LED microdisplay series in 0.11″, 0.13″, and 0.22″ sizes.
In February 2025, Leiyu introduced the PowerMatch® 1 full-color Micro LED light engine built around a 0.13-inch microdisplay, achieving 500,000 nits (white balance) and 0.5 lm luminous flux in a volume of only 0.18 cc—about 45% of a three-color color-combining module—and a weight of only 0.5 g, enabling near-invisible integration into eyeglass temples for lightweight designs. Samples have been delivered to multiple downstream customers and prototype collaborations are underway.
Technical breakthroughs: Monolithic full color via QD color conversion, using either inkjet printing or photolithography. In 2014, the team demonstrated the industry’s first full-color Micro LED microdisplay using QD inkjet printing; by 2015, chip diameter was reduced to 15 μm. However, the inkjet route suffers from limited alignment accuracy, line-width control, and contrast, impeding mass production. Since 2016, the team has focused on QD photolithography, embedding QDs in a photoresist via proprietary synthesis and protection chemistry, then patterning high-resolution, high-efficiency QD conversion films by standard lithography on GaN blue Micro LED, using blue excitation for red/green QDs to achieve monolithic full color.
3.3 Sitan Technology
Founded in 2018, Shenzhen Sitan Technology is a national “Little Giant” enterprise specializing in Micro LED semiconductor display R&D, production, and sales, focused on high-performance Micro LED chips and display modules.
Products and capacity: Product lines include 0.13″, 0.2″, and 0.45″ Micro LED, along with driver-IC and emitter-chip design and foundry services. Sitan has established a full chain from product development and pilot verification to mass production. In 2019, it built China’s first Micro LED pilot line in Shenzhen Longhua, completing technology transfer, materials validation, and process optimization. In 2022, it established Xiamen Sitan Integration (Phase-1 production base) and Xiamen Sitan Semiconductor (chip design base). In 2024, its Xiamen mass-production line came online with a designed annual capacity of 6 million display chips, advancing Micro LED from pilot to mass production.
