Method for fabricating a blazed grating

Abstract

This disclosure relates to a method () for fabricating a blazed grating. The method () comprises providing a substrate and a patterned mask layer () on the substrate, performing primary dry etching () of the substrate such that primary ions are accelerated towards a primary etch direction to impinge on the substrate, and performing secondary dry etching () of the substrate such that secondary ions are accelerated towards a secondary etch direction to impinge on the substrate. A primary projection of the primary etch direction and a secondary projection of the secondary etch direction onto the grating cross-sectional plane extend perpendicular to one and the other of a blaze facet direction and an anti-blaze facet direction, respectively, and ions accelerated towards a direction with a projection onto a grating cross-sectional plane perpendicular to the blaze facet direction are collimated to form a collimated ion beam for etching the substrate.