Gigaphoton Achieves 92W EUV Light Source
EUV has come closer to viability with the announcement by Gigaphoton that it has developed a 92W EUV light source output at 4.2 percent conversion efficiency (CE).
92W is still short of what is needed to enable a volume production EUV lithography machine. 125W is needed for a tool able to produce 60 wafers per hour and 250W is needed to make 120 wafers an hour.
However it is a step forward from the 30W being achieved at the start of the year and will relieve fears that EUV will not happen which would force the industry into the expensive option of multiple patterning.
The other developer of light sources for EUV, Cymer of San Diego which was bought by ASML in 2013, is still on about 20W. So it looks as if Gigaphoton is going to be the best bet – if its claims are to be believed – in this world there are claims which sometimes don’t stand up to inspection.
Gigaphoton says it is committed to continuing its R&D efforts, targeting 150W output by the end of 2014 and ultimately up to 250W output for high-volume manufacturing.
The 92W output was achieved by irradiating an Sn target (tin droplet) with a solid-state pre-pulse laser and a CO2 laser after combining and optimising these lasers.
The prototype LPP light source that has achieved 92W output allows emission of EUV by radiating ultra-small tin (Sn) droplets of less than 20 μm in diameter with the solid-state pre-pulse laser and main pulse CO2 laser. In addition, a combination of a high-output superconducting magnet and Sn etching allows suppression of Sn debris caused by radiation.
To maximise the life of the collector mirror, a high-output superconducting magnet generates a powerful magnetic field to guide unwanted debris caused by thermal expansion of the tin droplets towards the tin catcher.