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: 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.

Abstract: A system and method use a substrate with a pattern of individual, indiscrete alignment marks, i.e., the marks are separate and distinct from each other, and each mark is not divided into component parts. The pattern of marks is distributed over an area of the substrate, and the method also comprises the steps of providing a beam of radiation using an illumination system and an array of individually controllable elements to impart the beam with a pattern in its cross-section, providing a projection system to project the patterned beam onto the substrate, and providing a movement system to effect relative movement between the substrate and the projection system.

Abstract: In a method of measuring front to backside alignment error according to one embodiment, a transparent substrate has a plurality of marks on both the front and backside. The relative location of the marks on the front and backside of the substrate is determined to calculate the front to backside alignment error for the whole substrate. In a further embodiment, the substrate is rotated by 180° within the plane of the substrate and the front relative location of the marks is again determined.

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 element is placed in the alignment beam during alignment. The optical element serves to focus the alignment beam onto the substrate alignment mark when it is at a different focal length from the front surface of the substrate.

Abstract: To calibrate a front-to-backside alignment system a transparent calibration substrate with reference markers on opposite sides is used. A plane plate is inserted to displace the focal position of the alignment system from the top to bottom surface of the calibration substrate.

Abstract: An optical element is placed in the alignment beam during alignment. The optical element serves to focus the alignment beam onto the substrate alignment mark when it is at a different focal length from the front surface of the substrate.

Abstract: To calibrate a front-to-backside alignment system a transparent calibration substrate with reference markers on opposite sides is used. A plane plate is inserted to displace the focal position of the alignment system from the top to bottom surface of the calibration substrate.