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16 September 1994 Scatterometric sensor for lithography
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Abstract
Scatterometry, the analysis of light scattered by diffraction from periodic structures, is shown to be a versatile process control and metrology technique for use in microelectronics manufacturing. Contemporary inspection technologies, such as scanning force microscopy (SFM) and scanning electron microscopy (SEM), in general cannot be performed in-situ and are slow for real-time process control. Scatterometry, on the other hand, is rapid, nondestructive, inexpensive and might be used on-line. This paper will discuss applications of 2 - (Theta) scatterometry to developed photoresist focus/exposure matrices, often related to the manufacture of microelectronic devices. To test this technique we obtained and measured five identically processed wafers with nominal 0.5 micrometers line/0.5 micrometers space grating patterns. Each wafer is comprised of gratings created in Shipley 89131 negative photoresist and arranged in a matrix of incremental exposure doses and focus settings. The scatterometric CD measurements are consistent in comparison to cross- section and top-down SEM measurements of the same structures. The average deviation of 11 linewidth measurements from top down SEM measurements, over a broad exposure range, is 14.5 nm. In addition, the repeatability (1 - (sigma) ) of the 2 - (Theta) scatterometer is shown to be excellent: 0.5 nm for consecutive measurements and 0.8 nm for day to day measurements.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Christopher J. Raymond, Michael R. Murnane, S. Sohail H. Naqvi, and John Robert McNeil "Scatterometric sensor for lithography", Proc. SPIE 2336, Manufacturing Process Control for Microelectronic Devices and Circuits, (16 September 1994); https://doi.org/10.1117/12.186798
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