Asymmetric structures formed on a substrate and microlithographic methods for forming such structures. Each of the structures has a first side surface and a second side surface, opposite the first side surface. A profile of the first side surface is asymmetric with respect to a profile of the second side surface. The structures on the substrate are useful as a diffraction pattern for an optical device.

The mark position is measured with a multi-beam with high accuracy. A multi charged particle beam writing method includes forming a multi-beam in which charged particle beams are arranged with a predetermined pitch, irradiating a mark with beams in an on-beam region while shifting irradiation positions of the charged particle beams by sequentially changing the on-beam region in which beams in a partial region of the multi-beam are set to ON, the mark being provided at a predetermined position and having a width greater than the predetermined pitch, detecting a reflected charged particle signal from the mark, and calculating a position of the mark, and adjusting the irradiation positions of the multi-beam based on the calculated position of the mark, and writing a pattern.