Optimizing signal-to-noise ratio in optical imaging of defects on unpatterned wafers

    公开(公告)号:US11525777B2

    公开(公告)日:2022-12-13

    申请号:US17243548

    申请日:2021-04-28

    Abstract: A system for optical imaging of defects on unpatterned wafers that includes an illumination module, relay optics, a segmented polarizer, and a detector. The illumination module is configured to produce a polarized light beam incident on a selectable area of an unpatterned wafer. The relay optics is configured to collect and guide, radiation scattered off the area, onto the polarizer. The detector is configured to sense scattered radiation passed through the polarizer. The polarizer includes at least four polarizer segments, such that (i) boundary lines, separating the polarizer segments, are curved outwards relative to a plane, perpendicular to the segmented polarizer, unless the boundary line is on the perpendicular plane, and (ii) when the area comprises a typical defect, a signal-to-noise ratio of scattered radiation, passed through the polarizer segments, is increased as compared to when utilizing a linear polarizer.

    OPTIMIZING SIGNAL-TO-NOISE RATIO IN OPTICAL IMAGING OF DEFECTS ON UNPATTERNED WAFERS

    公开(公告)号:US20210349019A1

    公开(公告)日:2021-11-11

    申请号:US17243548

    申请日:2021-04-28

    Abstract: A system for optical imaging of defects on unpatterned wafers that includes an illumination module, relay optics, a segmented polarizer, and a detector. The illumination module is configured to produce a polarized light beam incident on a selectable area of an unpatterned wafer. The relay optics is configured to collect and guide, radiation scattered off the area, onto the polarizer. The detector is configured to sense scattered radiation passed through the polarizer. The polarizer includes at least four polarizer segments, such that (i) boundary lines, separating the polarizer segments, are curved outwards relative to a plane, perpendicular to the segmented polarizer, unless the boundary line is on the perpendicular plane, and (ii) when the area comprises a typical defect, a signal-to-noise ratio of scattered radiation, passed through the polarizer segments, is increased as compared to when utilizing a linear polarizer.

    Increasing signal-to-noise ratio in optical imaging of defects on unpatterned wafers

    公开(公告)号:US11474437B2

    公开(公告)日:2022-10-18

    申请号:US16861094

    申请日:2020-04-28

    Abstract: Disclosed herein is a method for increasing signal-to-noise (SNR) in optical imaging of defects on unpatterned wafers. The method includes: (i) irradiating a region of an unpatterned wafer with a substantially polarized, incident light beam, and (ii) employing relay optics to collect and guide, radiation scattered off the region, onto a segmented polarizer comprising at least four polarizer segments characterized by respective dimensions and polarization directions. The respective dimensions and polarization direction of each of the at least four polarizer segments are such that an overall power of background noise radiation, generated in the scattering of the incident light beam from the region and passed through all of the at least four polarizer segments, is decreased as compared to utilizing a linear polarizer.

    INCREASING SIGNAL-TO-NOISE RATIO IN OPTICAL IMAGING OF DEFECTS ON UNPATTERNED WAFERS

    公开(公告)号:US20210333719A1

    公开(公告)日:2021-10-28

    申请号:US16861094

    申请日:2020-04-28

    Abstract: Disclosed herein is a method for increasing signal-to-noise (SNR) in optical imaging of defects on unpatterned wafers. The method includes: (i) irradiating a region of an unpatterned wafer with a substantially polarized, incident light beam, and (ii) employing relay optics to collect and guide, radiation scattered off the region, onto a segmented polarizer comprising at least four polarizer segments characterized by respective dimensions and polarization directions. The respective dimensions and polarization direction of each of the at least four polarizer segments are such that an overall power of background noise radiation, generated in the scattering of the incident light beam from the region and passed through all of the at least four polarizer segments, is decreased as compared to utilizing a linear polarizer.

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