Next to Substrate and XLight, a third contender is looking to develop an alternative to ASML’s EUV light source. In an interview with Timestech, US startup Tau Systems outlines plans to use compact particle accelerators and X-ray free-electron lasers for semiconductor patterning. “Our goal is to replace the EUV light source for modern lithography machines with highly efficient X-ray lasers,” says Tau CEO Jerome Paye.
Tau’s light source architecture employs so-called laser wakefield acceleration, firing ultrashort laser pulses into a plasma to create a strong electric field that accelerates electrons over just a few millimeters. Those electrons then produce coherent X-ray radiation through a compact free-electron laser setup. Tau claims the entire system fits in a standard shipping container.
“Our light sources will have a high wall-plug efficiency from electrical to optical energy. Unused energy will be recaptured to further improve the efficiency and our X-ray laser, combined with the higher reflectivity of wavelength-matched reflective optics, will reduce operating costs by increasing production speed. Using a bright source of X-ray light will speed up production for each lithography step and reduce the need for multi-patterning. This will reduce the associated costs per wafer,” according to Paye.
ASML believes alternative EUV sources aren’t necessary. The firm’s roadmap will take laser-produced plasma sources to beyond 1,000 watts, at which point other aspects will be throughput-limiting, such as stage acceleration or photoresist sensitivity.
