| US 7,521,677 B2 | ||
| Method and device for distance measurement | ||
| Gero Walter, Westhausen (Germany); and Rainer Härle, Heidenheim (Germany) | ||
| Assigned to Carl Zeiss NTS GmbH, (Germany) | ||
| Filed on Dec. 20, 2006, as Appl. No. 11/642,249. | ||
| Claims priority of application No. 10 2005 061 687 (DE), filed on Dec. 21, 2005. | ||
| Prior Publication US 2007/0164215 A1, Jul. 19, 2007 | ||
| Int. Cl. H01J 37/26 (2006.01) | ||
| U.S. Cl. 250—310 | 28 Claims |
| 1. A method for determining a distance from a sample to be examined to at least one reference point, comprising:
modulating a signal to a first potential of the sample;
directing a primary particle beam at the sample, a secondary particle beam composed of particles being produced when the primary
particle beam strikes the sample and being directed away from the sample, and its particles having a second potential with
the modulated signal;
detecting the particles of the secondary particle beam and the signal modulated to the second potential of the particles of
the secondary particle beam; and
comparing the detected modulated signal with a reference signal, the distance being determined from a relationship between
the reference signal and the detected modulated signal.
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