High Brightness LEDs

LEDs (light emitting diodes) are light sources based on semiconductor devices. LEDs are used for a broad range of applications, such as backlight illumination of mobile phones or displays, traffic signals with low maintenance, car head lamps and rear lights, head-up displays, projectors and general illumination. They offer a number of advantages compared to other light sources, including long lifetime, low total lifecycle costs, compact size, easy implementation into end devices, and particularly, very high efficiency. The use of LEDs for illumination can save up to 85 % in energy consumption compared to standard light sources, offering the potential to reduce about 15 % of the total worldwide energy consumption if all standard light sources were substituted.

At epitaxy, the lattice constants of the epitaxial substrate and the active layer have to match very well to avoid lattice defects. Typical epitaxial substrates do not provide the appropriate properties for operation of the LED, such as high heat conductivity, transparency or high electrical conductivity.

Therefore, to produce high power LEDs, manufacturers often perform a layer transfer process step to transfer the active layer from the epitaxial substrate onto the final carrier with the suited properties. This is accomplished by eutectic bonding or by direct bonding on wafer level, depending on the process and LED material, with subsequent lift-off of the epitaxial substrate.

EV Group wafer bonding systems support the required layer transfer techniques.  Using multi-subtrate bond chucks, several LED wafers can be bonded in parallel. In addition to offering the lowest  cost of ownership through an optimized wafer bonding process, EV Group provides all levels of automation from manual to fully automated tools. Moreover various wafer to wafer alignment options, ranging from mechanical to high accuracy optical alignment, are available.

Please see our related products EVG®520IS and GEMINI® for detailed information.



Ostar high power LED 100 - 1000 lm. Courtesy of Osram.