Object Inspection Systems and Methods
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Accused Products
Abstract
Methods and systems for inspection of an object include the use of spectroscopic techniques for the detection of unwanted particles on an object'"'"'s surface, based on the different responses of the unwanted particles as compared with the object to be inspected due to their different materials. Time resolved spectroscopy and/or energy resolved spectroscopy of secondary photon emission from the surface of the object can be used to obtain Raman and photoluminescence spectra. The objects to be inspected can for example be a patterning device as used in a lithographic process, for example a reticle, in which case the presence of metal, metal oxide or organic particles can be detected, for example. The methods and apparatus are highly sensitive, for example, being able to detect small particles (sub 100 nm, particularly sub 50 nm) on the patterned side of an EUV reticle.
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Citations
85 Claims
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1-70. -70. (canceled)
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71. A method for inspection of an object, comprising:
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illuminating the object with a radiation beam; analyzing secondary photon emissions from the object with time resolved spectroscopy; and determining that a particle is present if a time resolved spectroscopic signal is detected that is different from a signal that would be emitted by the object in the absence of a particle; wherein said step of illuminating the object with a radiation beam comprises providing off-axis illumination from more than one direction. - View Dependent Claims (72, 73, 74, 75, 76, 77, 78, 79, 80)
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81. Apparatus for inspection of an object, comprising;
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a radiation source configured to emit a radiation beam onto the object; and a spectrometer configured to analyze secondary photon emissions from the object with time resolved spectroscopy and to determine that a particle is present if a time resolved spectroscopic signal is detected that is different from a signal that would be emitted by the object in the absence of a particle; and wherein said apparatus comprises means to direct radiation onto the object from more than one direction. - View Dependent Claims (82, 83)
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84. A lithographic apparatus for inspection of an object, comprising:
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a radiation source configured to emit a radiation beam onto the object; and a spectrometer configured to analyze secondary photon emissions from the object with time resolved spectroscopy and to determine that a particle is present if a time resolved spectroscopic signal is detected which is different from a signal that would be emitted by the object; and wherein said apparatus comprises means to direct radiation onto the object from more than one direction.
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85. A computer program product comprising a non-transitory computer readable medium having control logic stored therein that causes a computer to perform a data analysis method, comprising:
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first computer readable program code that causes the computer to illuminate the object with a radiation beam; second computer readable program code that causes the computer to analyze secondary photon emissions from the object with time resolved spectroscopy; and third computer readable program code that causes the computer to determine that a particle is present if a time resolved spectroscopic signal is detected that is different from a signal that would be emitted by the object in the absence of a particle; wherein the illuminating the object with a radiation beam comprises providing off-axis illumination from more than one direction.
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Specification