22 March 2008 Toward accurate feature shape metrology
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Over the last few years, the need for shape metrology for process control has increased. A key component of shape metrology is sidewall angle (SWA). However, few instruments measure SWA directly. The critical dimension atomic force microscope (CD-AFM) is one such instrument. The lateral scanning capability and the shape of the CD-AFM probe enable direct access to the feature sidewall. This produces profile information that could be used as a process monitor. Due to their relative insensitivity to material properties, CD-AFMs have been used as reference measurement systems (RMS) for measurands such as width. We present a technique for calculating the uncertainty of sidewall angle measurements using a CD-AFM. We outline an overall calibration strategy; address the uncertainty sources for such measurements, including instrument-related and parameter extraction; related; and discuss the way the calibration is transferred to workhorse instruments.
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Ndubuisi G. Orji, Ndubuisi G. Orji, Ronald G. Dixson, Ronald G. Dixson, Benjamin D. Bunday, Benjamin D. Bunday, John A. Allgair, John A. Allgair, "Toward accurate feature shape metrology", Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 692208 (22 March 2008); doi: 10.1117/12.774426; https://doi.org/10.1117/12.774426

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