Locating defects in solid material
First Claim
1. A method for locating defects and non-uniformities in a solid material that is otherwise substantially transparent to infrared (IR) light comprising,a) placing an IR focal plane array camera before a source of IR radiation and spaced therefrom,b) placing said material between said camera and said source,c) activating said source to emit an IR beam that is transmitted through said material to said camera, said camera obtaining an image of said material and said defects without scanning,d) processing said image ande) outputting said image in a desired form.
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Abstract
The invention provides method and apparatus for fast, accurate, and nondestructive imaging of defects and determining defect densities in solid materials including a semiconductor wafer. A wafer is illuminated on one side by an infrared (IR) source and a camera is placed on the other side of the wafer, to detect IR radiation that is transmitted through such wafer. The inventive method employs an imaging camera, e.g. a focal plane array camera, to image the so illuminated wafer. The wafer material must be substantially transparent in the camera bandwidth but can contain defects that absorb or scatter radiation in such bandwidth. Camera filters are used, for example, to select specific wavelengths or bands of wavelengths, to detect and image precipitates, subsurface defects, residual damage from polishing and other defects.
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Citations
16 Claims
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1. A method for locating defects and non-uniformities in a solid material that is otherwise substantially transparent to infrared (IR) light comprising,
a) placing an IR focal plane array camera before a source of IR radiation and spaced therefrom, b) placing said material between said camera and said source, c) activating said source to emit an IR beam that is transmitted through said material to said camera, said camera obtaining an image of said material and said defects without scanning, d) processing said image and e) outputting said image in a desired form.
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7. An apparatus for locating defects and non-uniformities in a solid material that is otherwise substantially transparent to infrared (IR) light comprising:
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a) a source of IR radiation, b) an IR focal plane array camera mounted before said source and spaced therefrom, c) means for placing said material between said camera and said source, d) means for activating said source to transmit an IR beam through said material to said camera, which obtains an image of said material and said defects without scanning, e) means for processing said image and f) means for outputting said image in a desired form. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification