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US 7,348,556 B2Granted
Method of measuring three-dimensional surface roughness of a structure
AssigneeFEI Company
InventorsPrasanna Chitturi, Liang Hong, Craig Henry, John Notte
Life of this patent
Estimating the term…
Abstract
An improved method of measuring the three-dimensional surface roughness of a structure. A focused ion beam is used to mill a succession of cross-sections or “slices” of the feature of interest at pre-selected intervals over a pre-selected measurement distance. As each cross-section is exposed, a scanning electron microscope is used to measure the relevant dimensions of the feature. Data from these successive “slices” is then used to determine the three-dimensional surface roughness for the feature.
Claims24
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.
12 more elements
A method for measuring the roughness of at least a portion of a surface of a feature on a workpiece, the method comprising:
- locating the feature on the workpiece;
- imaging the workpiece using a first charged particle beam column having a first field of view which includes the surface to be measured;
- selecting an identifiable fiducial within the field of view;
- directing a first charged particle beam at a first location on the feature at a known offset from the fiducial;
- milling the feature in order to expose a planar first cross-section of the surface to be measured, said first cross-section being substantially perpendicular to the surface to be measured;
- directing a second charged particle beam at the first location on the feature, said second charged particle beam having a second field of view that includes the fiducial and at least a portion of the first cross-section;
- determining the distance between the fiducial and the edge position of the surface to be measured at one or more data points on the first cross-section;
- imaging the first field of view with the first charged particle beam;
- directing the first charged particle beam at a second location on the feature at a known offset from the fiducial;
- milling the feature in order to expose a planar second cross-section of the surface to be measured, said second cross-section being substantially perpendicular to the surface to be measured;
- directing the second charged particle beam at the second location on the feature, said second charged particle beam having a second field of view that includes the fiducial and at least a portion of the second cross-section;
- determining the distance between the fiducial and the edge position of the surface to be measured at one or more data points on the second cross-section;
- and
- generating a three-dimensional characterization of the surface to be measured based upon the relative locations of the data points with respect to the fiducial.
11 more elements
A system for measuring the surface roughness of a feature, the system comprising:
- an ion beam for exposing at least two cross-sections of the feature;
- an electron beam for imaging the cross-sections and determining the distance between at least one edge of the feature and a fiducial;
- and
- a processing device adapted to determine the location and number of cross-sections required based upon operator input, direct the ion beam to the specified locations in order to mill the cross-sections, determine at least one edge position for the feature on each cross-section, measure the distance between each edge position and the fiducial for each cross-section, and calculate an edge roughness value for the feature surface based upon said distance and the location of each cross-section.
1 more element
Dependencies are inferred from the claim text.