Background: As progress on the nanofabrication has made semiconductor developed
rapidly, there is an increasing need in precise pitch standards to calibrate the structure of devices at
nanoscale. Nano-gratings fabricated by atom lithography are unique and suitable to act as precise
pitch standard because its pitch distance is directly traceable to a natural constant. As the scaling
down of nano-devices, it is very challenging to double the spatial frequency of nano-grating while
keeping the self-traceability in atom lithography.
Methods: In this study, the switching-detuning light mask is utilized for Cr atom lithography. During
a single deposition process, the standing wave frequency is switching from positive detuning to negative
Results: Nano-gratings fabricated using switching-detuning light mask is successfully replicated
with double spatial frequency and self-traceability. Non-uniformity between neighboring Cr lines
shows up with a corrected pitch of 107.15±0.35 nm.
Conclusion: Non-uniformity is mainly caused by the dipole force discrepancy between positive and
negative detuning light mask. Therefore, to increase the high uniformity of nano-gratings, the deposition
time of negative detuning should be at least twice as long as positive detuning. On the other
hand, to reduce the pitch uncertainty, it is necessary to reduce the distance between the atom beam
and reflection mirror as close as possible. These two significant optimization designs are promising
to increase the spatial frequency doubling performance with high uniformity and accuracy.
Keywords: Atom lithography, Standard material, Self-traceability, Double spatial frequency, Height uniformity, Pitch accuracy
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