Wyko, Inc.

Chris P Brophy

Donald K Cohen

Paul J Caber

James D Ayres

A method of profiling a rough surface of an object includes moving the object along a z axis so that a highest point of the rough surface is optically aligned with and outside of the focus range of a solid-state imaging array. An interferogram of the rough surface then is produced by means of a two beam interferometer. The solid-state imaging array is operated to scan the rough surface along x and y axes to produce intensity data for each pixel of the solid-state imaging array for a plurality of frames each shifted from the other by a preselected phase difference. The modulation for each pixel is computed from the intensity data. The most recently computed modulation of each pixel is compared with a stored prior value of modulation of that pixel. The prior value is replaced with the most recently computed value if the most recently computed value is greater. The object is incrementally moved a selected distance along the z axis, and the foregoing procedure is repeated until maximum values of modulation and corresponding relative height of the rough surface are obtained and stored for each pixel.

Rough surface profiler and method

A computerized phase shifting interferometer operates interactively with a user to correct surface profile data of a sample containing a film of material which is optically dissimilar to the material of a substrate. Profile data is measured, and optically dissimilar areas of the sample are identified by differences in measured height. The user is prompted to enter optical parameters for each identified area into the computer. Then the user is prompted to enter a best guess of the film thickness. A Newton approximation technique is performed by the computer to produce subsequent guesses of the film thickness until a computed thickness increment is below a predetermined value.

Method for rapid, accurate measurement of step heights between

The relative height variation and the thickness of a film of an object are simultaneously measured. A first interference pattern is produced for a calibration surface at a first wavelength and detected. Intensities of the first interference pattern are measured and used to compute a first group of phase values for each pixel. Intensity values of a point of the calibration samples are measured and used to compute a corresponding phase. A second interference pattern for the calibration surface is produced at a second wavelength and detected. Intensities of the second interference pattern are measured and used to compute a second group of phase values for each pixel. Intensity values of the point of the calibration surface are measured and used to compute a corresponding phase. A value for the surface height change .DELTA.h is computed by obtaining a linear combination of the corresponding phase values of the data groups. A drift value is computer by obtaining the difference between the first and second phase values at the point. A corrected surface height change value is computed for the calibration sample by adding the two. This procedure is repeated for a test surface to obtain its corrected surface height change. A corrected relative surface height change value .thrfore.h' is computed by subtracting the corrected surface height change value of the calibration surface from the corrected surface height change value for the test surface for each pixel. Computed .DELTA.h' values are compared to corresponding values from a mathematical model to obtain a best fit value of film thickness t for each pixel and the height error due to phase change is subtracted.

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White Bear Township, MN, United States of America

Chris P Brophy