Optics: measuring and testing – By configuration comparison – With photosensitive film or plate
Patent
1989-05-04
1991-03-12
Evans, F. L.
Optics: measuring and testing
By configuration comparison
With photosensitive film or plate
356369, G01B 1106, G01J 400
Patent
active
049990144
ABSTRACT:
An apparatus (20) for measuring the thickness of a thin film layer (32) on substrate (28) includes a probe beam of radiation (24) focused substantially normal to the surface of the sample using a high numerical aperture lens (30). The high numerical aperture lens (30) provides a large spread of angles of incidence of the rays within the incident focused beam. A detector (50) measures the intensity across the reflected probe beam as a function of the angle of incidence with respect to the surface of the substrate (28) of various rays within the focused incident probe beam. A processor (52) functions to derive the thickness of the thin film layer based on these angular dependent intensity measurements. This result is achieved by using the angular dependent intensity measurements to solve the layer thickness using variations of the Fresnel equations. The invention is particularly suitable for measuring thin films, such as oxide layers, on silicon semiconductor samples.
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Gold Nathan
Opsal Jon
Rosencwaig Allan
Willenborg David L.
Evans F. L.
Hantis K. P.
Therma-Wave, Inc.
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