Improvement of the quantum efficiency of micro LED by ALD passivation

Micro LED has been interested in the next generation display and been actively developing at many electronics manufactures and institutes for applications of AR/VR, wearable device and extra-large display as a core factor of the forth industry. Also it is evaluated to have superior properties to LED as well as OLED with low power consumption, excellent brightness, greater contrast, flexibility and reliability.

Micro LED of less than 10 µm size is required for displays needed high pixel per inch (PPI) but the quantum efficiency drop would occur by sidewall effect in the manufacturing process. Looking at the reason in detail, micro LED chips require separation of them by dry etching process and the sidewall effect reducing external and internal quantum efficiency happens not to optimize extraction of light by chemical contaminations and structural damages during the etching process.

ALD passivation on the sidewall of Micro LED after dry etching process

The passivation of sidewall by atomic layer deposition recover and remove the plasma damage by dry etching so that the quantum efficiency could be increased and also the ratio of improvement could increase as small as the size of micro LED.

Specially, the interest of productive ALD equipment has been gradually increased because of the excellent dielectric passivation by ALD Al2O3 thin films expecting to improve quantum efficiency.

NCD has been developing wafer based high throughput batch ALD system continuously enable to form high quality oxide passivation to improve the quantum efficiency of micro LED. By introduction of the system in production of micro LED, it could be expected to guarantee the productivity, high quality and performance reliability of high resolution micro LEDs for applications of AR/VR, flexible and wearable devices and extra-large displays.  

NCD Si wafer based batch ALD cluster system

Source: http://www.ncdtech.co.kr/2018/bbs/board.php?bo_table=eng_board_05&wr_id=47

New Liquid phase Atomic Layer Deposition (ALD) — A Breakthrough in ALD

Chemical engineers at Ecole Polytechnique Federale de Lausanne, Switzerland, invented ALD in the liquid phase that can produce materials indistinguishable from those made in the gas phase, with far cheaper equipment and no excess precursors. The researchers achieved this breakthrough by carefully measuring the ratio of the reacting precursors before injecting them onto the surface of a substrate. This way, they used exactly the right amount of precursor, with no leftovers that can cause unwanted reactions or be wasted. 

The new method also reduces costs by requiring only standard lab equipment for chemical synthesis. It can also be easily scaled up to coat more than 150 g of material with the same cheap equipment, without loss of coating quality. The technique can even achieve coatings that are usually not possible using gas-phase ALD, e.g., by using volatile precursors with extremely low volatility.

More information:


A cheaper way to scale up atomic layer deposition, Phys.org (LINK)

Benjamin P. Le Monnier et al. Atomic Layer Deposition on Dispersed Materials in Liquid Phase by Stoichiometrically Limited Injections, Advanced Materials (2019). DOI: 10.1002/adma.201904276

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By Abhishekkumar Thakur

ASM International launches A400(TM) Duo vertical furnace system with dual reactor chambers

New system addresses 200mm applications with high productivity and low cost of ownership

Munich - ASM International N.V. (Euronext Amsterdam: ASM LINK) today introduced the A400™ DUO vertical furnace system with dual reactor chambers for wafer sizes of 200mm and smaller. The system’s DUAL Boat reactors produce high throughput, increasing reactor utilization to a very high percentage, while ensuring low capex.

“The new A400™ DUO reactor ensures that ASM will extend its position as a leader in the market for Power, Analog, RF, and MEMS applications,” said Hichem M’Saad, ASM Executive Vice President, Global Products. “As 200mm manufacturing began its renaissance, driven by growth in for instance IoT devices, it became clear that our existing furnace technology could still achieve industry-leading results. Combining our technology with the latest innovations in robotics and controls has significantly enhanced the system’s manufacturing capabilities to meet today’s production targets.”

The new DUO is compatible with the original A400™, so existing process recipes can be easily transferred, accelerating system ramp. The system has secured production qualification from multiple customers in Europe, the United States and Asia, including several leaders in power, RF, and MEMS device manufacturing. To date over 20 reactors have been shipped, with a healthy outlook for further shipments.

ASM’s original A400™ vertical furnace system has a proven track record of more than 1000 reactors shipped to customers worldwide and over 25 years of maturity in semiconductor manufacturing. The new system has been modernized to support a variety of growing markets including silicon power, wide band gap semiconductor power, analog, RF and MEMS devices. With its updated control system, software with an intuitive graphical user interface, predictive maintenance by advanced control diagnostics, new robot, and plug-and-play installation, customers can count on the A400™ DUO delivering increased reliability with production output that achieves better repeatability, productivity, and time utilization.

Like its predecessor, the A400™ DUO offers a comprehensive portfolio of process applications including low pressure chemical vapor deposition (LPCVD) processes like doped silicon and silicon nitride films, diffusion processes such as wet oxidation and anneal processes.