Belgian research lab imec used a 13.5nm wavelength source for interference or holographic lithographic imaging on metal-oxide resist from Inpria under high numerical aperture conditions. Interference between two optical sources can be used to define regular arrays of features – such as lines and spaces – without the use of complex optical systems or photomasks in EUV lithography.
The development is a step forward to the production of circuits using high-NA lithography and a path down to 2nm and 1nm circuit definition.
KMLabs in Boulder, Co, is a manufacturer of ultrafast laser systems and is a partner in the AttoLab initiative with imec. KMLabs provided the laser source in a Lloyd's Mirror configuration on experiments on imec’s spectroscopy beamline. In this arrangement, light reflected from a mirror interferes with light directly emitted by the 13.5nm laser source, generating a finely detailed interference pattern suited for resist imaging.
The next step is to move the research on to 300mm-diameter wafers. It will be used to provide industry with patterned wafers for process development before the first high-NA (0.55) lithography system from ASML becomes available. That is the EXE5000.
"The high-flux laser source of KMLabs was used at a record small wavelength of 13.5nm, emitting a series of attosecond (10^18s) pulses that reaches the photoresist with a pulse duration that is a few femtoseconds (10 15s) in width," said John Petersen, principal scientist at imec and SPIE Fellow.
He added that current generation 0.33NA EUV lithography scanners are now being pushed to single-exposure limits.
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