Kla Corporation

Chong Shen

Guoheng Zhao

Bret Whiteside

An optical inspection system includes one or more single-material gratings to convert the polarization of light scattered from a target from an elliptical polarization that varies spatially across a collection pupil to a linear polarization that is uniformly oriented across the collection pupil. The one or more single-material gratings have phase retardation that varies spatially across the collection pupil in accordance with the elliptical polarization. The optical inspection system also includes a linear polarizer to filter out the linearly polarized light.

Single-material waveplates for pupil polarization filtering

An optical inspection system includes one or more gratings to convert the polarization of light scattered from a target from an elliptical polarization that varies spatially across a collection pupil to a linear polarization that is uniformly oriented across the collection pupil. The one or more gratings have phase retardation that varies spatially across the collection pupil in accordance with the elliptical polarization. The one or more gratings include at least one grating on a reflective substrate. The optical inspection system also includes a linear polarizer to filter out the linearly polarized light.

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San Jose, CA, United States of America

Chong Shen