Measurement of the top surface of an object with/without transparent thin films in white light interferometry
AssigneePhase Shift Technology, Inc.
InventorShouhong Tang
Life of this patent
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Abstract
White light interferometry is used to obtain the height information of the topmost surface of an object having a transparent thin film on it. N frames of data are acquired from an interferometer while a white light fringe pattern is scanning through a field of view. The modulation fringe envelope R(n) is calculated for every pixel; and the topmost surface position at every pixel is determined as an offset of R(n).
Claims8
A method for obtaining the height information of the top surface of an object having a transparent thin film on it using white light phase-shifting interferometry including:
- acquiring a set of N frames of data from an interferometer while the optical path difference (OPD) between a reference and the object is changing, with each of the frames having a plurality of pixels;
- and calculating a modulation fringe envelope R(n) for each pixel;
- determining the topmost surface calculating position nc at each pixel as an offset of R(n).
A method for obtaining the height information of the topmost surface of an object having multiple transparent thin films on it using white light phase-shifting interferometry including:
- acquiring a set of N frames of data from an interferometer while the optical path difference (OPD) between a reference and the object is changing, with each of the frames having a plurality of pixels;
- calculating modulation fringe envelopes R(n) for each pixel;
- and determining the topmost surface calculating position nc at each pixel as an offset of R(n).
A method for obtaining the height information of the top surface of an object having a transparent thin film on it using white light phase-shifting interferometry including:
- acquiring a set of N frames of data from an interferometer while the optical path difference (OPD) between a reference and the object is changing, with each of the frames having a plurality of pixels;
- calculating a modulation fringe envelope R(n) for each pixel;
- obtaining a fringe modulation (M) for each surface at each pixel;
- and establishing the topmost surface calculating position Nc from the fringe modulation M1 for the top surface where the fringe modulations (M2 . . . i) are equal to zero.
Dependencies are inferred from the claim text.