> Multi-patterning: A method where multiple exposures are used to create smaller features. (Would like to know more) It might be better to start by considering

> Multi-patterning: A method where multiple exposures are used to create smaller features. (Would like to know more) It might be better to start by considering ways to play with shadows cast by a single photolithography mask... The Wikipedia article on "Computational Lithography" is a good place to start: https://en.m.wikipedia.org/wiki/Computational_lithography https://en.m.wikipedia.org/wiki/Computational_lithography A particularly fascinating technique, linked in that article, is the use of "Phase-Shifting Photo Masks": https://en.m.wikipedia.org/wiki/Phase-shift_mask https://en.m.wikipedia.org/wiki/Phase-shift_mask And then there are ways to play with diffraction effects, at the edges of the opaque shapes of the mask: https://en.wikipedia.org/wiki/Optical_proximity_correction https://en.wikipedia.org/wiki/Optical_proximity_correction In addition to diffraction and phase shift patterns, you can create shapes by illuminating the mask and wafer with more than one light source. It may be helpful to consider this "multiple illumination" of a single photo mask in the context of a "double slit" interference pattern: https://en.m.wikipedia.org/wiki/Diffraction_from_slits#Multiple_slits https://en.m.wikipedia.org/wiki/Diffraction_from_slits#Multi... After you've run out of tricks, you have write over the shapes laid down by a single mask, running the wafer through the process with a different mask. I find the current Wikipedia article for multi-patterning to be a bit more difficult to understand, but it's certainly worth the effort. After studying this article a bit, I think it might help to start in the middle of the article, at "Pitch Splitting". A second read of the article, starting at the top, may then provide more context: https://en.wikipedia.org/wiki/Multiple_patterning#Pitch_splitting https://en.wikipedia.org/wiki/Multiple_patterning#Pitch_spli... . (Ironic: the article on Multiple Patterning requires multiple passes!)