Design of diffractive optical elements for off-axis illumination in lithography system[J]. Optics and precision engineering, 2008, 16(11): 2081-2086.DOI:
Being one of the very important RETs (Resolution Enhancement Technology)
OAI (Off-axis Illumination) is widely applied to optical lithography system. The advantages of adopting DOE (Diffractive optical element) to realized OAI are not only the flexible illumination shape available but also the controllability of the intensity profile in addition to the higher efficiency of light source. In this paper
the four DOEs that have 8 phase level are designed by using the step-iterative algorithm
and the four elements can realize dipole
quadrupole
annular and Bulls-Eye illuminations respectively. The simulation results show that their efficiency of light source are all better than 80% and the RMS (Root-Mean-Square) of intensity profile compared with the ideal ones are all smaller than 7%.