Abstract: A method of determining a thickness of a residue layer on a substrate includes: (1) taking a first set of optical scatterometry measurements on the substrate after an etching procedure; (2) taking a second set of optical scatterometry measurements on the substrate after a post-etch cleaning procedure; (3) calculating a difference measurement between the first set and second set of optical scatterometry measurements; (4) determining an initial thickness measurement of the residue layer based on the difference measurement by applying a first dispersion model; and (5) adjusting the initial thickness measurement by applying a second dispersion model based on a material composition of the residue layer. Numerous other aspects are provided.

Abstract: A method of determining a thickness of a residue layer on a substrate includes: (1) taking a first set of optical scatterometry measurements on the substrate after an etching procedure; (2) taking a second set of optical scatterometry measurements on the substrate after a post-etch cleaning procedure; (3) calculating a difference measurement between the first set and second set of optical scatterometry measurements; (4) determining an initial thickness measurement of the residue layer based on the difference measurement by applying a first dispersion model; and (5) adjusting the initial thickness measurement by applying a second dispersion model based on a material composition of the residue layer. Numerous other aspects are provided.

Abstract: A method and apparatus for testing and characterizing features formed on a substrate. In one embodiment, a test structure is provided that includes a test element having a first side and an opposing second side. A first set of one or more structures defining a first region having a first local density are disposed adjacent the first side of the test element. A second set of one or more structures defining a second region having a second local density are disposed adjacent the second side of the test element. A third set of one or more structures defining a third region having a first global density are disposed adjacent the first region. A fourth set of one or more structures defining a fourth region having a second global density are disposed adjacent the second region.

Abstract: A method and a test-structure for determining an offset between lithographic masks are described. In one embodiment, an image of a first mask is provided in a patterning layer on a substrate. The image of the first mask comprises a first set of lines, each line separated by a distance D. An image of a second mask is then provided in the patterning layer. The image of the second mask comprises a second set of lines, each line also separated by the distance D. The second set of lines interlays the first set of lines to form a grating with a distance L between each of the lines of the first set of lines and the respective corresponding lines of the second set of lines. The offset between the first and second masks is determined by calculating the difference between the distance L and a predetermined value K, where 0<K<D. In a specific embodiment, K=½D.

Abstract: A method and apparatus for testing and characterizing features formed on a substrate. In one embodiment, a test structure is provided that includes a test element having a first side and an opposing second side. A first set of one or more structures defining a first region having a first local density are disposed adjacent the first side of the test element. A second set of one or more structures defining a second region having a second local density are disposed adjacent the second side of the test element. A third set of one or more structures defining a third region having a first global density are disposed adjacent the first region. A fourth set of one or more structures defining a fourth region having a second global density are disposed adjacent the second region.