| CPC G01N 21/211 (2013.01) [G01B 11/0641 (2013.01)] | 18 Claims |
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1. A device for measuring a profile of an object surface of a flat object comprising unknown materials, comprising:
a beam splitter for splitting a light beam of a light source;
an optical interferometry measuring system and an ellipsometry measuring system for simultaneously measuring a measurement region on the object surface; and
an analysis unit, wherein:
a) the optical interferometry measuring system comprises:
a beam divider for dividing an interferometry light beam of a light source into a reference beam and a measuring beam;
a reference mirror for reflecting the reference beam;
a detector unit for receiving and analyzing an analysis beam of the optical interferometry measuring system, wherein
the measuring beam is directed to a measurement region on the object surface for reflection and, after reflection, is directed as an object beam to the beam divider,
the reference beam is reflected at the mirror and directed as a mirror beam to the beam divider, and
the object beam and the mirror beam interfere after impinging on the beam divider and are fed as an analysis beam to the detector unit for analyzing;
b) the ellipsometry measuring system comprises:
a polarizer for polarizing an ellipsometry light beam and routing the ellipsometry light beam to the measurement region on the object surface; and
an ellipsometry sensor having a polarization filter configured to analyze a polarization state of a receiving sensor beam,
wherein the ellipsometry light beam is directed to the measurement region on the object surface and, after reflection at the measurement region of the object surface, impinges on the ellipsometry sensor as a sensor beam;
c) the beam splitter is designed for splitting a light beam of the light source into the interferometry light beam and the ellipsometry light beam; and
d) the analysis unit is designed to simultaneously process the analysis beam analyzed in the detector unit and the sensor beam received in the ellipsometry sensor and to determine a profile height in the measurement region on the object surface without using material parameters of the unknown materials of the object to be measured, wherein
a correction of measurement results of the detector unit is performed in the analysis unit based on:
(i) an effective refractive index determined with the ellipsometry measuring system of the object to be measured;
(ii) an effective absorption coefficient determined with the ellipsometry measuring system of the object to be measured; and
(iii) an effective layer thickness of a substitute layer which combines an effective optical effect of one or more layers of the object, and
(i), (ii), and (iii) are used to calculate a real reflection coefficient and a phase shift of the object beam.
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