LumArray’s ZP-150 maskless photolithography system is based on zone-plate-array lithography (ZPAL), a technology invented at MIT’s NanoStructures Lab. The following graphics illustrate ZPAL and
show LumArray’s ZP-150 within its environmental enclosure.
Schematic of the operating principle of zone-plate-array lithography (ZPAL).
Photo of LumArray’s ZP-150 system within its environmental enclosure.
The ZP-150 achieves high throughput for patterns of arbitrary geometry, covering up to a full wafer area, using an array of up to 1000 independently programmed diffractive-optical microlenses.
An example of such arbitrary patterning is the hologram shown under Micro- & Nanofabrication services.
The ZP-150 achieves nanometer-level accuracy in the placement of pattern elements by combining a high-stability mechanical design with correction in software for systematic placement errors.
In brief, placement errors are measured using a proprietary phase-sensitive interferometry that enables the ZP-150 to achieve ~10 nm pattern-placement accuracy over full-wafer fields, rivalling
state-of-the-art e-beam photomask writers. This capability is important in diffractive-optical applications such as precision x-ray spectroscopy. Photonic applications based on preserving temporal
coherence likewise require the long-range spatial-phase coherence the ZP-150 provides.
Currently, the ZP-150 utilizes microlenses with numerical apertures (NA) of 0.55 and a source of 405 nm wavelength, limiting linewidth resolution to ~300 nm. As in any photolithography system,
resolution is improved with higher NA and/or shorter wavelength. Using microlenses of 0.85 NA, linewidths of 122 nm were demonstrated previously. LumArray is currently investigating optimal methods
of fabricating diffractive-optical microlens arrays of higher NA and higher focal efficiency.