18 September 1996 Deep field reflection mode for high-resolution surface relief exploration by coherence probe microscopy
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Proceedings Volume 2782, Optical Inspection and Micromeasurements; (1996) https://doi.org/10.1117/12.250774
Event: Lasers, Optics, and Vision for Productivity in Manufacturing I, 1996, Besancon, France
Abstract
In high resolution optical reflection microscopy, one of the problems of using large numerical aperture objectives is that the depth of field is very narrow, for example only 0.4 micrometers for a X100 objective (NA equals 0.95). When working on microelectronic structures that may be many microns deep, this is a several imitation for analyzing possible defects or measuring linewidths etc. because many of the features are out of focus. In the case of analyzing deep rough surfaces, the image can become confused due to stray light from out of focus details. Coherence probe microscopy is a new method for automatic measurement of deep surface relief using white light interferometry. The nanometric depth discrimination due to the temporal coherence of the illumination beam makes it possible to profile deep structures while maintaining sub-micron lateral resolution. In this paper we demonstrate a new mode in which the maximum intensity of the fringe packet is noted at each pixel to give a full depth of field reflection image. The aspect of the image is similar to that produced by SEM (though not with as high a lateral resolution) but without the necessity for sample preparation or vacuum conditions. We show results on different materials and structures with a depth of field of up to 48 micrometers and a lateral resolution of less than 0.2 micrometers .
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Paul C. Montgomery, Jean-Marc Lussert, "Deep field reflection mode for high-resolution surface relief exploration by coherence probe microscopy", Proc. SPIE 2782, Optical Inspection and Micromeasurements, (18 September 1996); doi: 10.1117/12.250774; https://doi.org/10.1117/12.250774
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