According to the article, rule based patterns are already used, but inverse lithography is required in more unique or problematic cases. Ideally they would use

According to the article, rule based patterns are already used, but inverse lithography is required in more unique or problematic cases. Ideally they would use it in all cases, maybe we end up with slightly wobbly but tolerable features for the more generic or less esoteric features that use the heuristics based approach. > Even a change to the thickness of a material can lead to the need for a new set of photomasks You can imagine the light spreading out through the other side of the mask, diffracting and interfering with neighbouring features through some radius. That it's not trivial to compute suggests the number of combinations within this radius is large enough to not be highly cacheable.