PHABLE™ - enabling photonics

What is PHABLE?

PHABLE (for 'photonics enabler') is a patented technology platform that has been developed by Eulitha for low-cost fabrication of periodic nanostructures that are needed in many photonic applications.

The applications are almost unlimited including:

  • LED light extraction
  • Nanopatterned sapphire substrates (NPSS) for LEDs
  • Wiregrid polarizers for LCD displays
  • Nanopatterned solar (photovoltaic) cells
  • Antireflection layers
  • Color filters
  • Nanowire LEDs
  • Nano-particle production
  • Biosensors

Eulitha offers a unique photolithography system called PhableR 100 as well as a wide collection of standard patterns based on this technology. Patterning projects on customer substrates as well as custom fabrication solutions to address different customer requirements in photonic and other areas are also on offer. Eulitha has an extensive patent portfolio on this new technology with more than 10 patents issued or pending.

PHABLE is a mask based UV photolithography technology that takes full advantage of the existing infrastructure such as photoresists and photo masks. It enables the creation of periodic structures, such as arrays of holes on a hexagonal or square lattice, or linear gratings over large areas with high throughput.

The unique advantage of PHABLE is its ability to generate an optical image that has a very large depth of focus. This is unlike any of the conventional proximity, contact or projection lithography technologies. Therefore printing on non-flat surfaces, such as LED wafers, is accomplished with ease. In contrast to holographic lithography, the image is defined by a pattern on a mask and so printing a different pattern only requires a simple change of the mask. It also enables simultaneous printing of various patterns on a single chip or a wafer in much the same way different circuits are printed on silicon wafers.

Photonic Crystals on LEDs

Improvement of the light extraction efficiency from active regions of GaN- based LEDs has been a major challenge for the LED industry. The high refractive index of the layers in which the light is generated means that a significant portion of the light is trapped inside which is eventually absorbed and lost. Patterning the surface of the LEDs with a photonic crystal pattern can improve the efficiency of these devices by a factor of 2-3. It also gives significant control over the angular distribution of the emitted light. The economic and environmental gains that may be derived from higher-efficiency LED devices are immense.

Similar photonic patterns are also needed for other applications such as nanowire-based LEDs and photovoltaic devices. Heteroepitaxy on patterned Si substrates and epitaxial layer overgrowth (ELO) methods also require periodic patterns. The list of emerging applications in the photonics sector that require nanostructures continues to grow. Currently available lithographic technologies either do not have the necessary performance such as the imaging resolution or the ability to print over non-flat surfaces, or their cost is prohibitively high. PHABLE technology is ideally suited to address these emerging manufacturing problems.

Publications

Sub-wavelength printing in the deep ultra-violet region using Displacement Talbot Lithography
Li Wang, Francis Clube, Christian Dais, Harun H. Solak, Jens Gobrecht, Microelectronic Engineering, Volume 161, 104–108, (2016).

Phase shifting masks in Displacement Talbot Lithography for printing nano-grids and periodic motifs
Harun H. Solak, Christian Dais, Francis Clube, Li Wang, Microelectronic Engineering, Volume 143, 74–80, (2015).

Using photolithography for photonic LEDs
Featured Article in Compound Semiconductor, November/December, Vol. 16, No. 8, p.33 (2010)

Displacement Talbot lithography: a new method for high-resolution patterning of large areas
H. Solak, C. Dais, F. Clube, Optics Express, Vol. 19, p. 10686 (2011)

New Optical Lithography Method for Advanced Light Extraction in LEDs
Review Article in LED Professional, May/June 2013 issue

Diffraction gratings printed using PHABLE technology
High resolution 2D pillar array - 140nm period
Hexagonal array, pitch 520nm - hole diameter 250nm
Linear grating, pitch 300nm - linewidth 140nm
Triangular grid, 3um period
Triangular grid, 3um period, 400nm line-width
4" wafer patterned with PHABLE
4" wafer fully patterned with array of holes on hexagonal lattice (period 600nm)
PhableR 100 Photolithography tool