(Color online) High precision mapping of surface topography using a noncontact laser probe microscope: (a) The nonplanar substrate is mounted on a special cassette in the location marked “S.” The cassette has four registration marks at the four corners indicated by “1,” “2,” “3,” and “4,” (b) three-dimensional height map of a 6 in. Si wafer that has been tilted to create a height variation of 1 cm. Area mapped = 60 mm × 60 mm, (c) map of a 1 in. diameter planoconvex lens (R = 30.9 mm). Area mapped = 10 mm × 10 mm, and (d) map of a Si wafer that has been wet etched to create 200 μm deep trenches. Area mapped = 60 mm × 60 mm.
(Color online) High resolution gratings on Si wafer with 7.08 mm height variation: (a) The 3 in. Si wafer mounted on a special fixture, which produces a height variation of 10 mm, (b)–(f) gratings at heights of 2.54 mm, 0.78 mm, −1.00 mm, −2.78 mm, and −4.54 mm with respect to the reference plane, respectively, and (g) higher magnification of the gratings.
(Color online) Quantitative analysis of the patterned gratings with a height variation of 7.08 mm. The dots indicate the average line width at 5differentheight locations. Average line width for gratings across 60 mm× 30 mm area = 46.27 ± 8.18 nm.
(Color online) Laser metrology for the evaluation of field stitching accuracy of patterns on a 3 in. Si wafer with a height variation of 5.24 mm: (a) A total of 16 chips were patterned over a 30 mm × 30 mm area of the wafer; (b) each chip is symmetrically divided into four parts that are on four separate fields; (c) the x- and y-direction shifts between neighboring fields are tabulated. Maximum field stitching error was 25.18 nm with an average field stitching error of 1.06 ± 24.62 nm.
(Color online) Gratings patterned on a 1 in. diameter planoconvex lens (R = 30.9 mm) with a 2.2 mm height variation: (a) Side view of the lens, and (b) gratings at the center of the lens which is 2.2 mm above the reference plane. Average line width was measured to be 48.42 ± 10.31 nm.
(Color online) High resolution patterning on top and bottom of etched trenches in Si wafer: (a) The trenches were anisotropically etched in KOH to a depth of 200 μm. The openings measure 5 mm × 5 mm. (b) Patterned vernier marks at the bottom of a trench for the evaluation of field stitching accuracy. The field boundary is shown in the white dotted line. The vernier marks in the neighboring fields are offset by 8 nm. For ideal field stitching, the mark in the middle should line up perfectly at the field boundary (c) Patterned vernier mark at the bottom of a trench for the evaluation of field placement accuracy.
Measurements of field placement accuracy on a 3 in. Si wafer with a height variation of 5.24 mm. A total of 16 chips were patterned over a 30 mm× 30 mm area of the wafer. Four chips across the wafer were used for the evaluation. Nine metrology marks were measured on each chip. The shift between two layers for each chip is tabulated. Maximum field placement error was 40.41 nm with an average field placement error of 20.53 ± 31.92 nm. (unit: nm)
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