Patent
Optical system and method for angle-dependent reflection or transmission measurement
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TLDR
In this article, a high numerical aperture objective lens is used to focus a set of light bundles to a common point on a sample surface, and the individual light bundles are then focused to the common spot by a high-NAP objective lens so as to provide a range of incidence angles on a surface.Abstract:
An angle-dependent reflectometer or transmissometer includes an optical imaging array in the incident and reflected or transmitted light path that breaks up an incident light beam into mutually spatially incoherent light bundles. The individual light bundles are then focused to a common spot by a high numerical aperture objective lens so as to provide a range of incidence angles on a sample surface. In a reflectometer, reflected light returns through the objective lens and imaging array and is imaged onto a detector array where different incidence and reflection angles are received by different groups of detection elements. In the angle-dependent transmissometer, the imaging array and high numerical aperture focusing objective lens are used for illuminating a spot on the sample, with a second high numerical aperture collection objective lens and detector array used for receiving transmitted light over a wide range of collection angles. The angle-dependent reflectance or transmittance measurement provided by the detector array can be analyzed to determine a desired characteristic parameter of the illuminated area of the sample surface. For example, a periodic text pattern on a wafer or mask surface can be illuminated to obtain a linewidth measurement. The break up of the light by the imaging array into light bundles allows the spot size to be controlled independently of the range of illumination angles so that areas much larger than the diffraction limit can be illuminated.read more
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References
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Patent
Method and apparatus for measuring thickness of thin films
TL;DR: In this paper, the angular dependent intensity measurements were used to solve the layer thickness using variations of the Fresnel equations, which is particularly suitable for measuring thin films, such as oxide layers, on silicon semiconductor samples.
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Masato Shibuya,Makoto Uehara +1 more
TL;DR: In this article, an illumination optical arrangement comprises light source means emitting a coherent light beam, and means for forming a substantially incoherent light source from the coherent light beacon, and optical means for form a plurality of optical paths for directing the coherent beam passed through the predetermined scanning area to different secondary scanning areas.
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Two-phase optical inspection method and apparatus for defect detection
TL;DR: In this paper, a method and apparatus for inspecting the surface of articles, such as chips and wafers, for defects, includes a first phase of optically examining the complete surface of the article inspected by scanning its complete surface at a relatively high speed and with an optical beam of relatively small diameter.
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Optical scatterometer having improved sensitivity and bandwidth
TL;DR: In this paper, an improved optical scatterometer includes a multiple detector array that enables the measurement of sample microstructure over an increased range of spatial frequency, where one array of optical detectors is positioned in a plane perpendicular to the plane containing an incident laser beam and a specularly reflected beam.
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TL;DR: In this article, a chrome-on-glass diffraction grating is illuminated with a laser and a photodetector mounted behind the photomask measures the scattered power in each diffracted order.