8 June 1998 Sampling requirements for the analysis of misregistration
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With the adoption of increasingly tight design rules (less than 100 nm) for overlay, it is critical that the sample used to quantify wafer misregistration be as representative as possible. In this paper, we look at misregistration after two layers, both chosen as most critical to overlay design rules for a logic technology process. Several wafers at each layer were patterned, after which they were mapped on a KLA overlay tool. The mapping was done on all sites with 5 measurement points on each site in an X pattern. The wafers also had been subject to chemical-mechanical polish and its associated mechanical stresses. We identify representative extreme sites using a statistical technique called archetypal analysis. We describe how many sample points are required to adequately describe the distribution of overlay across a wafer.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ramkumar Subramanian, Ramkumar Subramanian, William D. Heavlin, William D. Heavlin, Eileen M. Coons, Eileen M. Coons, Bharath Rangarajan, Bharath Rangarajan, } "Sampling requirements for the analysis of misregistration", Proc. SPIE 3332, Metrology, Inspection, and Process Control for Microlithography XII, (8 June 1998); doi: 10.1117/12.308781; https://doi.org/10.1117/12.308781

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