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 how the calibration is transferred to workhorse instruments.
Proceedings Title: Proceedings of SPIE, Metrology, Inspection, and Process Control for Microlithography XXII
Conference Dates: February 22-29, 2008
Conference Location: San Jose, CA
Pub Type: Conferences
sidewall angle, critical dimension atomic force microscope, uncertainty