The critical dimension atomic force microscope (CD-AFM), which is used as a reference instrument in lithography metrology, has been proposed as a supplemental instrument for contour measurement and verification. However, although data from CD-AFM is inherently three dimensional, the planar two-dimensional data required for contour metrology is not easily compared with the top-down CD-AFM data. This is largely due to the limitations of the CD-AFM scanning strategy. We describe scanning techniques and profile extraction methods to obtain contours from CD-AFMs, and some of the limitations. Potential sources for error for this approach are described, and a rigorous uncertainty model is presented. Our objective is to show which data acquisition and analysis methods could yield optimum contour information while preserving some of the strengths of CD AFM metrology. We present comparison of contours extracted using our technique to those obtained from the scanning electron microscope (SEM), and the helium ion microscope.
Proceedings Title: Proc. SPIE Metrology, Inspection, and Process Control for Microlithography XXVI
Conference Dates: February 12-17, 2012
Conference Location: San Jose, CA
Pub Type: Conferences
contour metrology, critical dimension atomic force microscope, scanning electron microscope, helium ion microscope