DEVICE AND METHOD FOR MOIRe MEASUREMENT OF AN OPTICAL TEST SPECIMEN

Abstract

The invention relates to a device for Moire measurement of an optical test specimen, comprising a grating arrangement composed of a first grating (25, 25', 35, 35'), which is positionable in the optical beam path upstream of the test specimen, and a second grating (11, 11', 11", 41, 51, 61, 71, 81, 91, 101, 111, 121, 131, 141), which is positionable in the optical beam path downstream of the testspecimen, an evaluation unit having at least one detector (12, 12', 12", 22, 22', 32, 32', 42, 52, 62, 72, 82, 92, 102, 112, 122, 132, 142) for evaluating Moire structures produced by superimpositionof the two gratings in a detection plane situated in the optical beam path downstream of the second grating, and at least one aperture stop (14, 14', 14", 24, 24', 34, 34'), by which the light distribution produced after emergence of light from the second grating can be shaded regionally in such a way that only light of a subset of all field points on the second grating reaches the detection plane.

Description

[0001] Cross References to Related Applications [0002] This application claims priority from German patent application DE 10 2016 202 198.2 of February 12, 2016. The content of this DE application is incorporated by reference into the text of the present application. technical field [0003] The present invention relates to apparatus and methods for moiré measurements of optical test samples. Background technique [0004] Microlithography is used to manufacture microstructural components such as integrated circuits or LCDs. The microlithographic process is performed in a so-called lithographic exposure apparatus that includes an illumination device and a projection lens. The image of the mask (= reticle) illuminated by the illumination device, in this case projected by a projection lens onto a substrate (e.g. silicon wafer) in order to transfer the mask structure to the photosensitive coating of the substrate. [0005] In practice, there is a need to determine imaging ...

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Problems solved by technology

[0008] However, a problem that actually occurs here is that, due to the angular distribution of the light emitted from the test object or the projection lens 6 or the moiré mask 8, things like Figure 16 The overlap of corresponding light cones assigned to different field points is shown ( Figure 16 denoted in "9a" and "9b"), the result is that in each case the light used to evaluate different field points partially coincides in the corresponding detection plane

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