Patent ID: 7348556

Claim:
A method of determining three-dimensional roughness of the surface of a feature, the method comprising: (a) defining the target area encompassing at least a portion of said feature surface; (b) imaging the target area; (c) locating a unique fiducial within the target area but separated from the feature, said fiducial having at least one fiducial axis substantially parallel to the feature surface; (d) determining the number and location of a plurality of feature cross-sections; (e) directing an ion beam at a the location of a first cross-section within the target area; (f) milling the feature in order to expose the cross-section of the feature thereby producing a substantially planar face on said exposed cross-section; (g) directing an electron beam at both the planar cross section and the fiducial; (h) determining the location of said fiducial axis; (i) determining the edge position for the desired feature surface on the exposed cross-section with respect to said fiducial axis; (j) re-imaging the target area; (k) re-locating the unique fiducial; (l) directing an ion beam at the next cross-section location within the target area; (m) repeating steps (f) through (l) until all cross-sections have been exposed and imaged; and (n) calculating an edge roughness value based upon the edge position for the desired feature surface with respect to the fiducial axis for all cross-sections.