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LEDinside: 2017 Micro LED Next Generation Display Industry Trend

Following LCD and OLED, micro-LED is now one of the next-generation display technologies that are in the spotlight. Besides companies working in the global display supply chain, major technology brands including Apple and Sony are increasingly involved in the development of micro-LED as they are drawn to its possibilities. Currently, those that are engaged in this field aim to bring down the production cost. LEDinside finds that the potential scale of the future micro-LED market – one that would replace the entire current LCD display chain including BLU, polarizer and other components – could reach US$30~40 billion.
At LEDforum 2017, LEDinside will address that Micro LED key technology development cover four sectors, including epi wafer and chip, transfer, bonding, and color conversion. Besides, LEDinside will share Micro LED display market trend at LEDforum 2017.

Tackling the Key Challenges of Micro LED MOCVD Processing

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Micro LED is gaining high attraction as an emerging display technology for both wearables and TV displays due to its unique advantage in terms of color and brightness control as well as low power consumption. To displace LCD or OLED technology for these market segments, the technology will have to both fulfill technical and cost requirements. Looking throughout the value chain, both technical and commercial challenges stem from the very MOCVD processing of the wafers.
AIXTRON is presenting how the micro LED displays differ from traditional SSL application and highlights the key challenges which needs to be tackled to enable a successful MOCVD processing. Due to its sub-millimeter dimensions, micro LED’s require an advanced transfer technology and an improved wafer uniformity level. For the epitaxy processing this translates into tightened specifications in regards to wafer uniformity and defect levels. AIXTRON is presenting an unique system solution which is exactly tailored to meet this new level of challenges.

Break

Volume Manufacturing of Micro LED: Where Optics meets Semiconductor Standards

With our evaporation and sputtering equipment Evatec already delivers mass production solutions to the worlds leading LED manufacturers . Our broad process portfolio stretches from metal “lift off” solutions, through TCO-ITO processes, all the way to complex optical mirror stacks like full DBR layers.
Evatec ITO process know how also includes different solutions for damage-free ITO processing for green and blue Micro LED. Our new FTC (Facing-Target-Cathode) sputter source can be integrated on all Evatec cluster platforms including CLUSTERLINE® 200 and enables the combination of damage-free contact films and a highly transmissive bulk layer e.g. hot ITO.
Leveraging our long experience in optical and semiconductor process technologies, our RADIANCE sputter cluster is optimized for complex interference stacks using features like “closed-loop optical monitoring” for thickness control and “plasma emission monitoring” for perfect stoichiometry . Here we show outstanding film results up to 8” for typical low/high refractive index metal oxides.
Transferring these optical processes and know how onto semiconductor type cluster platforms enables new levels of particle performance and introduction of semiconductor.

Growth Substrate Backside Finish and Wafer-Level Laser Lift-Off Unit Processes for micro-LED Fabrications

Blue and green micro-LED fabrications usually require wafer-level laser lift-off of the epi layer from the sapphire growth substrate. The presenter will review recent process and equipment advancements in sapphire backside preparations and subsequent wafer-level lift-off processes. The discussions will focus on employing lasers using DPSS source for lift-off operations. For red colored, GaAs based mirco-LEDs, usually wafer thinning is required. The presenter will showcase recent results in GaAs wafer thinning and target thickness control for bonded wafer stacks. The technologies presented here evolved from mature processing technology platforms, hence, are ready for HVM adaptations.

Lunch Break

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Monolithic LED Micro-display: LEDoS Technologies and Applications

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Large area LED displays and general lighting are now commonplaces. The use of LED in micro-display is rare but is recently attracting more attention. LEDs have advantages in terms of efficiency, brightness, lifetime, temperature stability and robustness, compared with other existing micro-display technologies.
Although LED micro-displays have been investigated, high resolution monolithic micro-display with decent visual quality is challenging. Non-optimized bumping technology and bowing of micro-LED array causing difficulty in flip-chip bonding are the major issues. We have developed two different approaches to illustrate high resolution micro-displays with much better bonding yield. A 1700 pixel per inch (PPI) passive-matrix and a 400 × 240 active-matrix micro-LED arrays bonded on ASIC have been demonstrated.
Realization of full color LED micro-display is also a big challenge because it is not practical to selectively grow three different epi-layers emitting at different wavelengths on a single substrate for three primary colors. Dedicated for projection display application, we demonstrated a novel 3LED light engine that can project full color video on screen. 3LED consists of a trichroic prism that combines RGB images generated from three LED micro-displays based on AlGaInP (Red) and GaN (Green and Blue) materials. For near-to-eye display application, RGB quantum dots were printed on micro-LED array by aerosol jet printing, achieving full color LED micro-display with high image quality.

Color Conversion Solution for Full Color Micro LED Display

Micro-LED display has been getting a lot of attention in the last couple years due to its potential to deliver high peak brightness while consuming significantly less power than any of the existing display solutions. Combined with its fast response time, micro-LED display is considered to be a perfect solution for wearables, smartwatches, augmented reality (AR), virtual reality (VR) and mixed reality (MR). There are basically two ways of implementing micro-LED display, 1) monolithic integration and 2) heterogeneous integration. The monolithic integration approach is an obvious one, however it usually associates with a higher cost than the other approach. The heterogeneous approach has potential to deliver significantly lower cost but faces huge challenges in manufacturing yield and output. For either approach, it is possible to use red, green and blue (RGB) LED chips together or blue chips only with a color converter such as quantum dots to convert blue into red and green. The latter becomes very attractive due to significant simplification of driving circuitry and manufacturing process. This talk will discuss in detail on the requirements for quantum dot color converters for micro-LED display and the current development status of quantum dots for this application.

Fully-Integrated Active Matrix Programmable Micro-LED Display System-on-Panel (SoP)

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High pixel per inch (PPI) and high resolution micro-LED (µLED) displays are attracting more and more attentions. The increasing pixel number requires a large amount of bonding pads and brings huge difficulties to micro-LED system design and lowers power efficiency as well. It is urgent to integrate row and column driving circuits onto the micro-LED panel. Here we report a fully integrated active matrix programmable micro-LED system on panel (SoP) with ultraviolent (UV) and blue emission wavelengths. The micro-LED SoP was achieved by integrating micro-LED arrays with silicon-based PMOS driving panel using fine-toned flip-chip bonding technology. With fully integrated scan and data circuits, the number of bonding pads was greatly reduced and large amount of metal interconnection lines were saved. The micro-LED SoP panel was mounted on a periphery driving board and representative characters were displayed successfully.

Break

Micro LED on Silicon in Pico-projector Application

We want to introduce the active matrix Micro LED based on high resolution and digital modulation silicon backplane and use this kind of backplane to drive Micro LED ( Micro LED on Slicon). Currently, micro display cannot be used widely in various applications because of these weaknesses of lack brightness, too much power consumption and short life time. Compared to other micro display, Micro LED on Silicon have a lot of advantages such as high-brightness, long life time and power-saving features etc. Because of these benefit Micro LED on Silicon will be a very important component in AR/VR and pico-projector application.

Monolithic Integration of Micro-LEDs with Thin Film Silicon Transistors for High-Brightness Microdisplays

Emissive micro-LED microdisplays have been a topic of interest due to the need for high luminance levels in emerging applications, like Augmented Reality. Lumiode's technology uses III-V LED and directly integrates thin film silicon transistors to combine both efficient light emitters with active matrix circuits. We will present an overview of our technology and the need for micro-LEDs in new emerging markets.