15 October 1984 Moire Technique For Overlay Metrology
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Proceedings Volume 0480, Integrated Circuit Metrology II; (1984) https://doi.org/10.1117/12.943061
Event: 1984 Technical Symposium East, 1984, Arlington, United States
Overlay performance is usually determined by exposing wafers twice, processing the wafer, and then using vernier or electrical probe techniques to measure the overlay error. In this paper, we describe a very different technique where the overlay error is evaluated in situ on the lithographic exposure tool. The basis of this approach is the examination of moire fringes between the projected image of a grating test mask and a grating test wafer. This is a particularly attractive approach to lithographic metrology because the moire fringes contain information about both resolution and overlay error. A measurement instrument has been constructed which attaches to a MicralignTM projection printer. The fringe intensity is measured by a solid state detector array positioned on an image of the illuminated arc-shaped field. Since the overlay measurement can be done many times per second, we can directly observe vibrations between mask and wafer.
© (1984) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
T. A. Brunner, T. A. Brunner, S. D. Smith, S. D. Smith, "Moire Technique For Overlay Metrology", Proc. SPIE 0480, Integrated Circuit Metrology II, (15 October 1984); doi: 10.1117/12.943061; https://doi.org/10.1117/12.943061

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