Patent ID: 9036130
Filing Date: 2015-05-19
Classification: G03F

Abstract:
1. A device for transmission image sensing for sensing an aerial image in a lithographic exposure apparatus, the device comprising: a projection system arranged to form, at an image side of the projection system, an aerial image of an object mark, the image side having a numerical aperture larger than 1, the object mark configured to minimize effects of destructive interference at an optimum aligned position, and the object mark having a first mark element in a first direction and a second mark element in a second direction, wherein the first direction and the second direction are orthogonal; and a detector comprising a first slit pattern and a second slit pattern, each having features arranged to correspond to at least a part of the aerial image, the first and second slit patterns being configured to be exposed to the aerial image, and the detector further being configured to detect detection radiation transmitted by the first and second slit patterns, wherein where d represents a dimension of a smallest feature of the first and second slit patterns, λ represents a wavelength of the detection radiation, and NA represents the numerical aperture of the image side.