Sub-100 nm lithography with pattern and partial coherence control

This paper describes optical patterning of sub-lithographic wavelength features using only conventional chrome-on-glass binary photomasks without phase-shift features. The sub-100 nm patterns were obtained through manipulation of masks bias designs and partial coherence control of the lithographic radiation. The key factors in the design of experiments are the density and design of masks patterns and the partial coherence of exposure radiation system used. Based on the study, smallest resolution of 36% that of designed value can be obtained for features of 75 nm using a 200 nm designed line width. Besides indication of proposed process' resolution limits for further applications, advantages of the method allows its application to applications requiring sub-100 nm critical dimensions through use of biased pattern designs, especially feasible in devices such as deep sub-micrometer comb drives actuators in nano-microelectromechanical structures; metal-semiconductor-metal photodetectors, and nanophotonic crystal structures, etc.