22 March 1988 New Technique For Submicron Linewidth Measurement
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Proceedings Volume 0849, Automated Inspection and High-Speed Vision Architectures; (1988); doi: 10.1117/12.942828
Event: Advances in Intelligent Robotics Systems, 1987, Cambridge, CA, United States
Abstract
We propose a novel technique to accurately measure submi-cron linewidths on photomasks and wafers. We do this by translating a phase-shifting mask across the surface containing the line whose width we wish to measure. With a Fourier-transform lens, we detect the intensity of the zero-order spatial component of the light coming from the surface as a function of the mask position. We show that the detected intensity curve varies dramatically and exhibits sharp changes in direction corresponding to the boundaries of the line. From this informa-tion the linewidth is readily apparent. We present a theoretical analysis and several computer simulations, showing that the technique is relatively independent of variations in the optical reflectance and in the height between the patterned feature and any substrate. Unlike other optical imaging methods for measur-ing linewidths, a high-resolution microscope and precise calibration are not needed. Using a laser, lateral resolution of 0.1 μm , well beyond the limit predicted by the Rayleigh criterion, is theoretically achievable. Preliminary experimental results agree well with the theoretical prediction.
© (1988) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yiping Xu, Alan Mar, Glen Wade, Evelyn Hu, John Landry, "New Technique For Submicron Linewidth Measurement", Proc. SPIE 0849, Automated Inspection and High-Speed Vision Architectures, (22 March 1988); doi: 10.1117/12.942828; https://doi.org/10.1117/12.942828
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KEYWORDS
Photomasks

Reflectivity

Semiconducting wafers

Phase shifts

Microscopes

Optical imaging

Computer simulations

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