22 May 1995 Effective alignment techniques and their implementation to enhance total overlay accuracy on highly reflective films
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Comparative analysis of the total overlay accuracy on aluminum (Al) and chemical vapor deposition tungsten (CVD-W) was carried out as a function of the available alignment techniques over the various process conditions. In the case of Al films, they were prepared at the various sputtering temperatures, thicknesses, and step heights. The total accuracy was also examined associated with standard and off-axis illumination (OAl). The effect of the sputtering temperature of single and dual Al deposition has been especially investigated in a view of surface roughness, which significantly affects total overlay accuracy. It was observed that CVD-W film can be an alternative of Al film. As the Al film deposition temperature decreases, it was found out that random requisition error with a large distribution was improved by implementing an off-axis alignment (OAA) technique with a visual broadband light source. Meanwhile, Al thickness was not so much critical to overlay accuracy comparing with Al sputtering temperature. And also scaling error determined by asymmetric alignment mark shape was minimized according to the optimization of exposure data file. Minimum detectable step height of alignment mark was down to 300 angstrom using a sensitive alignment techniques over the Al film.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Young-Hong Min, Seung-Chan Moon, Hyeong-Soo Kim, Ki-Ho Baik, Soo-Han Choi, "Effective alignment techniques and their implementation to enhance total overlay accuracy on highly reflective films", Proc. SPIE 2439, Integrated Circuit Metrology, Inspection, and Process Control IX, (22 May 1995); doi: 10.1117/12.209212; https://doi.org/10.1117/12.209212

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