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.

Semiconductor materials used for LEDs have a relatively high refraction index compared to air. This is the reason why typically only light beams with a small angle to the surface  can exit the device. This effect can be avoided by patterning the surface with feature sizes similar to the wavelength of the LED. The out coupling of the light and therefore the efficiency of the LED is improved significantly. 

EV Group's imprint lithography technology allows for patterning the surface of the substrate with optical components:

  • Gratings
  • Lenses (spherical and aspherical)
  • Photonic crystals

    Imprint lithography is a high-throughput wafer-level process. With Imprint Lithography a dedicated UV sensitive liquid material, which is applied on the wafer, is imprinted by mechanical casting of a stamp, and cured with UV-light. Compared to competing, alternative techniques Imprint Lithography is a low cost solution for structuring the wafer surface from the nanometer to the millimeter scale.
    As wafer level manufacturing processes are anyway favored due to their cost reduction potential,  customers in the LED manufacturing market can benefit from an additional feature offered by Imprint Lithography techniques: the integration of beam shaping optics, which are state-of-the-art in CMOS image sensors.

    Please see our related product IQ Aligner®, EVG®620, EVG®520HE and solution Wafer Level Optics for detailed information.

    Standard stamps for Imprint Lithography are not only quite expensive, they are  consumables too since they have mechanical contact with the mold. In response EV Group developed a working stamp solution with very low total cost of ownership.

    With the new approach, the desired structure is transferred from a master stamp to the working stamp in a first, step and repeat Imprint Lithography process step. While the valuable master stamp will usually be the size of one single die, wafer-size the working stamp - which can consist of far less expensive material - can afterwards be used for the imprint lithography process to structure the wafer surface.

    Please see our related product EVG®770 for detailed information.


    Imprint of a photonic crystal for efficient light coupling. Feature sizes: diameter 350 nm, 700 nm pitch. Source: EVG.

    Single side 300 mm lens wafer fabricated by soft UV Imprint Lithograhpy. Source EVG.