Method for Producing a Pattern of Features by Lithography and Etching

A method for producing a pattern of features on a substrate may involve performing two exposure steps on a resist layer applied to the substrate, followed by a single etching step. In the two exposures, the same pattern of mask features is used, but with possibly differing dimensions and with the pattern applied in the second exposure being shifted in position relative to the pattern in the first exposure. The shift, lithographic parameters, and/or possibly differing dimensions are configured such that a number of resist areas exposed in the second exposure overlap one or more resist areas exposed in the first exposure. When the pattern of mask features is a regular 2-dimensional array, the method produces of an array of holes or pillars that is denser than the original array. Varying the mask patterns can produce different etched structure shapes, such as a zig-zag pattern.