Laser imaging system for inspection and analysis of sub-micron particles
First Claim
1. An imaging system comprising:
- means for inspecting a semiconductor die to determine the efficacy of a process previously performed on the semiconductor die, the means for inspecting comprisinga multiline laser light source that emits laser light of a plurality of wavelengths,means for directing the laser light toward the semiconductor die, andmeans for measuring a first intensity of laser light reflected from the semiconductor die; and
means for analyzing a defect on the semiconductor die to determine the nature and origin of the defect.
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Accused Products
Abstract
A laser imaging system is used to analyze defects on semiconductor wafers that have been detected by patterned wafer defect detecting systems (wafer scanners). The laser imaging system replaces optical microscope review stations now utilized in the semiconductor fab environment to examine detected optical anomalies that may represent wafer defects. In addition to analyzing defects, the laser imaging system can perform a variety of microscopic inspection functions including defect detection and metrology. The laser imaging system uses confocal laser scanning microscopy techniques, and operates under class 1 cleanroom conditions and without exposure of the wafers to operator contamination or airflow. Unlike scanning electron microscopes (SEMs) that have previously been used for defect analysis, the laser imaging system will not damage samples or slow processing, costs significantly less to implement than an SEM, can produce a three dimensional image which provides quantitative dimensional information, and allows sub-surface viewing of defects lying beneath dielectric layers. The laser imaging system is adaptable to cluster or in-situ applications, where examination of defects or structures during on-line processing can be performed.
349 Citations
29 Claims
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1. An imaging system comprising:
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means for inspecting a semiconductor die to determine the efficacy of a process previously performed on the semiconductor die, the means for inspecting comprising a multiline laser light source that emits laser light of a plurality of wavelengths, means for directing the laser light toward the semiconductor die, and means for measuring a first intensity of laser light reflected from the semiconductor die; and means for analyzing a defect on the semiconductor die to determine the nature and origin of the defect. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An imaging system comprising:
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a laser imaging means for imaging a surface of an object using laser light, the laser imaging means comprising a laser light source that emits a beam of laser light; a spatial filter for focusing the beam on a pinhole aperture; a lens arranged between the pinhole aperture and the surface, the lens having a focal plane; means for scanning the beam and directing the scanned beam toward the object through the lens; and means for measuring the intensity of laser light reflected from the object and back through the lens and the pinhole aperture, wherein the measured intensity of laser light reflected from the object is at a maximum intensity when the surface lies in the focal plane of the lens; and a white-light imaging means for imaging a surface of an object using white light, the white-light imaging means comprising a white light source that emits white light; means for directing the white light toward the object; means for measuring the intensity of white light reflected from the object; and a filter that prevents laser light from impinging upon the means for measuring the intensity of white light and allows white light to impinge upon the means for measuring the intensity of white light; wherein the laser light imaging is performed at the same time as the white light imaging. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An imaging system for detection or analysis of defects in or on an object, the system comprising:
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means for producing light of a first polarity; means for directing the light of a first polarity through a pinhole aperture and toward the object such that a portion of the light of a first polarity is reflected by a surface of the object; a lens mounted between the pinhole aperture and the surface, the lens for focusing the light of a first polarity to a focal point on or within the object; means for measuring the intensity of the light reflected from the object and back through the pinhole aperture, wherein the intensity of light reflected from the object is at a maximum intensity when the surface and the focal point of the lens are coincident; means for changing the polarization of the light reflected by the object so that the polarization of the light reflected by the object is of a second polarity different than the first polarity; means for filtering the reflected light so that the reflected light passing through the means for filtering has an intensity directly proportional to the distance between the focal point of the lens and the surface; and means for analyzing the intensity of to create an image of the object.
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22. A laser imaging system for imaging a surface of an object, the system comprising:
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a laser light source that emits a beam of laser light, the beam focussed on a pinhole aperture; a beam scanner configured to receive the beam from the pinhole aperture and output a scanned beam toward the surface; a lens arranged between the beam scanner and the surface, the lens having a focal plane; and a sensor generating an output signal proportional to the intensity of laser light reflected from the object and back through the lens, the beam scanner, and the pinhole aperture to impinge on the sensor, wherein the output signal of the sensor indicates a maximum intensity of reflected laser light when the surface lies in the focal plane of the lens. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
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Specification