Spectrum-Integral Talbot Effect for UV Photolithography With Extended DOF

A route of spectrum-integral Talbot lithography (SITL) with extended depth-of-focus (DOF) for microfabrication of periodic structures was explored under broadband incoherent illumination in this letter. The transmitted diffraction fields by different spectral components integrate together to generate the successive periodicity since certain distance along the direction of propagation. The mechanism of DOF extension was derived and numerically elucidated using the spectrum of a practical ultraviolet source. Experiments of proximity lithography in term of the numeric results were performed to record the intensity distributions within the DOF area. Finally, the results reveal the validity of SITL and its potentials in high-fidelity lithography of periodic micropatterns with almost unlimited DOF and thus enhanced resolution.