Villigen, Switzerland--Eulitha AG has developed a photolithography technology for low-cost and high-throughput fabrication of periodic photonic nanostructures. The company says the technology has "practically unlimited depth of focus."
The technology solves an ongoing problem faced in the fabrication of high-resolution photonic structures, says Eulitha, as standard photolithography equipment either lacks the required resolution or its cost is prohibitively high. The approach enables the formation of periodic nanostructures over large areas for such applications as LEDs, solar cells, and flat-screen displays.
One exposure, multiple patterns
Dubbed Phable (for photonics enabler), it is a mask-based UV-lithography system. Due to its large depth of focus, nonflat substrates such as LED wafers can be patterned uniformly and reproducibly, says Eulitha, noting that the technology also allows combinations of different patterns such as linear diffraction gratings and arrays of holes on hexagonal or square grids to be printed using a single exposure. The resolution of the printed features can be as small as one quarter of the illumination wavelength. The masks required by Phable are made using standard chromium-on-quartz mask-writing technology. The technology will be presented at the MNC 2010 conference (November 9 to 12, 2010; Fukuoka, Japan).
Fabricating photonic crystals needed to raise the light-extraction efficiency of LEDs is one application of the new technology. Unlike the nanoimprint method that is now commonly used, Phable avoids contact between the mask and the wafer and does not require consumable soft stamps.
Other uses include the fabrication of nanowire-based LEDs and photovoltaic devices, heteroepitaxy on patterned silicon substrates, and epitaxial lateral overgrowth used in blue-emitting diode lasers. Wire-grid polarizers, as required for both LCD displays and projectors, may also be produced with the Phable technology.
Eulitha offers samples and wafer batch processing services to companies and researchers. It also offers laboratory lithography tools for 2 to 4 in. wafers that are suitable for product development. High-volume production tools with throughput in excess of 100 wafers per hour will be available in the near future.
For more information, go to www.eulitha.com.
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