Imaging overlay targets using moiré elements and rotational symmetry arrangements

    公开(公告)号:US12105433B2

    公开(公告)日:2024-10-01

    申请号:US17675912

    申请日:2022-02-18

    CPC classification number: G03F7/70633

    Abstract: A metrology target may include a first rotationally symmetric working zone with one or more instances of a first pattern and a second rotationally-symmetric working zone with one or more instances of a second pattern, where at least one of the first pattern or the second pattern is a Moiré pattern formed from a first grating structure with a first pitch along a measurement direction on a first sample layer and a second grating structure with a second pitch different than the first pitch along the measurement direction on a second sample layer. Centers of rotational symmetry of the first and second working zones may overlap by design when an overlay error between the first sample layer and the second layer is zero. A difference between the centers of rotational symmetry of the first and second working zones may indicate an overlay error between the first and second sample layers.

    OBLIQUE ILLUMINATION FOR OVERLAY METROLOGY

    公开(公告)号:US20220357674A1

    公开(公告)日:2022-11-10

    申请号:US17684179

    申请日:2022-03-01

    Abstract: An overlay metrology system may include an overlay metrology tool suitable for measurement of an overlay target on a sample, the overlay target including one or more grating structures with patterned features distributed along one or more measurement directions. The overlay metrology tool may include an objective lens and an illumination pathway to illuminate the overlay target with two or more oblique illumination lobes distributed among one or more illumination distributions such that, for each of the measurement directions, diffraction orders of the one or more illumination distributions by the overlay target that are collected by the objective lens exclusively include a 0-order diffraction lobe and a single first-order diffraction lobe from at least one of the two or more illumination lobes. The overlay metrology tool may further include at least one detector to image the sample and a controller to generate overlay measurements based on the images.

    METROLOGY TARGET FOR SCANNING METROLOGY

    公开(公告)号:US20210311401A1

    公开(公告)日:2021-10-07

    申请号:US17354307

    申请日:2021-06-22

    Abstract: A metrology system may include a controller coupled to a scanning metrology tool that images a sample in motion along a scan direction. The controller may receive an image of a metrology target on the sample from the scanning metrology tool, where the metrology target comprises a first measurement group including cells distributed along a transverse direction orthogonal to the scan direction, and a second measurement group separated from the first measurement group along the scan direction including cells distributed along the transverse direction. The controller may further generate at least a first metrology measurement based on at least one of the cells in the first measurement group, and generate at least a second metrology measurement based on at least one of the cells in the second measurement group.

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