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Proceedings Paper

Calibration Of Optical Systems For Linewidth Measurements On Wafers
Author(s): D. Nyyssonen
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Paper Abstract

In contrast to earlier work with nearly opaque photomasks, optical linewidth measurements on wafers encompass materials with a much wider variation in optical parameters and material profiles. Accurate optical edge detection requires corrections for both the relative reflectance and phase at the line edge because of the partial coherence present in optical microscopes. However, measurement systems which cannot provide the appropriate corrections and cannot detect edge location accurately can be calibrated. Since the correction curve is material dependent, calibrated standards are theoretically required for each step in the wafer fabrication process where linewidths are measured. In the proposed approach for thin layers (less than 200 nm), a small number of etched silicon-dioxide-on-silicon wafers can be used for calibration of a large class of wafer materials. Examples of wafer calibration data for filar, image-splitting and image-scanning systems are given. The problems associated with accurate linewidth measurement and calibration for thick layers are also discussed.

Paper Details

Date Published: 5 September 1980
PDF: 8 pages
Proc. SPIE 0221, Developments in Semiconductor Microlithography V, (5 September 1980); doi: 10.1117/12.958632
Show Author Affiliations
D. Nyyssonen, Electron Devices Division/National Bureau of Standards (United States)

Published in SPIE Proceedings Vol. 0221:
Developments in Semiconductor Microlithography V
James W. Dey, Editor(s)

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