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20 September 1976 Optical Determination Of Semiconductor Device Edge Profiles
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The edge profiles of semiconductor devices and developed resist images are usually determined with a scanning electron microscope. This paper presents a fast, nondestructive optical method by which edge profiles can be taken at any point on a wafer of any size. The edge profile is deduced from the angular distribution of the light scattered by the edge. The angular distribution is a signature of the edge profile, and contains information about such characteristics as double slopes, hooks or lips, rounding of corners, very low-angle slopes, and even step heights of the order of 500 Å. Such complex edge structure can be evaluated by simply calibrating the angular distribution with SEM observations. By applying a simple model of light diffraction from an edge to simple slopes, we are able to deduce edge slope, slope length, and step heights. This analysis can be applied to slope angles from 5° to 80° and step heights from 0.3 to 2.5 μm. The values thus deduced agree well with those obtained with the SEM. The method can be applied routinely at critical steps in production to monitor process variations across a wafer or from wafer to wafer.
© (1976) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
M. A. Habegger "Optical Determination Of Semiconductor Device Edge Profiles", Proc. SPIE 0080, Developments in Semiconductor Microlithography, (20 September 1976);


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