Fabrication of 50 nm period gratings with multilevel interference lithography.
We have developed a multilevel interference lithography process to fabricate 50 nm period gratings using light with a 351.1 nm wavelength. In this process multiple grating levels patterned by interference lithography are overlaid and spatial-phase aligned to a common reference grating using interferometry. Each grating level is patterned with offset phase shifts and etched into a single layer to achieve spatial-frequency multiplication. The effect of the multilayer periodic structure on interference lithography is examined to optimize the fabrication process. This process presents a general scheme for overlaying periodic structures and can be used to fabricate more complex periodic structures.
Chang
Chih-Hao
CH
Space Nanotechnology Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. chichang@mit.edu
Zhao
Y
Y
Heilmann
R K
RK
Schattenburg
M L
ML