| US 7,551,292 B2 | ||
| Interferometric Height Measurement | ||
| Gernot Brasen, Jr., Mainz (Germany); Christian Laue, Mainz (Germany); Matthias Loeffler, Eisenberg (Germany); and Heiko Theuer, Mainz (Germany) | ||
| Assigned to International Business Machines Corporation, Armonk, N.Y. (US) | ||
| Filed on Mar. 31, 2008, as Appl. No. 12/59,017. | ||
| Application 12/059017 is a continuation of application No. 11/481101, filed on Jul. 05, 2006, granted, now 7,397,569, filed on Jul. 08, 2008. | ||
| Claims priority of application No. 03006539 (DE), filed on Mar. 24, 2003. | ||
| Prior Publication US 2008/0180689 A1, Jul. 31, 2008 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. G01B 11/30 (2006.01) | ||
| U.S. Cl. 356—495 [356/516] | 7 Claims |
| 1. An interferometer for measuring height said interferometer comprising:
means for generating a first coherent light beam and a second coherent light beam; means for reflecting at least said first
coherent light beam from a first region into a first return beam and reflecting said second coherent light beam from a second
region into a second return beam;
means for measuring at least a first reflectivity of said first region;
means for determining a topography-dependent phase shift of said first return beam and said second return beam based on said
first reflectivity, wherein said determining means further comprise means for determining said topography-dependent phase
shift with reference to a curve relating said first reflectivity to a material-dependent phase shift; and
means for measuring a height based on said topography-dependent phase shift.
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