A method for etching a desired complex pattern in a first face of a substrate, including: simultaneous etching of at least a first and a second sub-pattern through the first face of the substrate, the etched sub-patterns being separated by at least one separating wall, a width of the first sub-pattern being greater than a width of the second sub-pattern at the first face, and a depth of the first sub-pattern being greater than a depth of the second sub-pattern in a direction perpendicular to the said first face; and removing or eliminating the separating wall to expose the desired complex pattern.