18 June 2007 Proposal on MEMS-based interferometric profiler for in-situ etching depth control
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Abstract
An innovative instrument for fast and accurate surface profiling of three dimensional patterned microstructures and insitu plasma etching depth control is proposed. Several advantages of the design make it promising for in-situ metrology. First, the system constitutes a common-path interferometer with the spatial phase shift between the reference and the object beams, thus the vibration and improper positioning of an object have a minor impact on the system performance. Second, no mechanical translation of either object or sensor is required; instead, a digital micromirror array is used for scanning the surface. It results in a higher processing rate, better measuring reproducibility, and easy adaptation of the method to specifics of the fabrication technology or object under test. Third, recording a full fringe for a particular pair of object's pixels is done within a single frame of a CCD camera. Also, multiple fringes for the whole line of object pixels can be captured at once. Then only 1-D scan is required to recover the depth profile of a 2-D object area. The experimental setup has been constructed to verify major principles of the method and measurement of test samples have been realized and compared to alternative measuring methods.
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Andrei G. Smirnov, Juergen Schreiber, Uwe Richter, Ingo Wullinger, "Proposal on MEMS-based interferometric profiler for in-situ etching depth control", Proc. SPIE 6616, Optical Measurement Systems for Industrial Inspection V, 66161Y (18 June 2007); doi: 10.1117/12.726538; https://doi.org/10.1117/12.726538
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