Abstract: A lithographic substrate provided with an alignment mark, the alignment mark having a plurality of features spaced apart from one another, each feature being spaced apart from adjacent features by a different distance is disclosed. Further, there is disclosed a method of aligning a lithographic substrate provided with an alignment mark which has a plurality of features spaced apart from one another, each feature being spaced apart from adjacent features by a different distance, the method including measuring a distance between two of the features on the substrate, comparing the distance with a recorded set of distances, and determining from the comparison the position of the substrate.

Abstract: A method of calculating an angle of an alignment beam of an alignment system in, for example, a lithographic projection apparatus includes measuring the position of at least two alignment marks. These two alignment marks are manufactured on a measurement substrate or they can be arranged on a reference on a substrate table of the lithographic apparatus itself. The second mark is covered by a transparent plate. Then, the position of the two marks is measured using the alignment system. Due to refraction of the alignment beam in the transparent plate, the alignment beam is shifted when returning to the alignment system. The shift of the alignment beam results in a deviated measured position of the second mark. This shift can be calculated because the distance between the two marks is known. The shift is used to calculate the angle of the alignment beam. The angle can be used to improve a FTBA error verification method.

Abstract: An optical position assessment apparatus and method has an illumination system that supplies an alignment beam of radiation, and positional data is derived from reflections of the alignment beam. A substrate is supported on a substrate table and a projection system is used to project the alignment beam onto a target portion of the substrate. A positioning system causes relative movement between the substrate and the projection system. An array of lenses is arranged such that each lens in the array focuses a respective portion of the alignment beam onto a respective part of the target portion. An array of detectors is arranged such that each detector in the array detects light reflected from the substrate through a respective lens in the array and provides an output representative of the intensity of light reflected to it from the substrate through the respective lens.