Method and apparatus for locating/sizing contaminants on a polished planar surface of a dielectric or semiconductor material
First Claim
1. A method for locating/sizing contaminants on a bare, highly polished, and planar surface of a dielectric or semiconductor material, comprising the steps of:
- focusing a coherent beam of diffraction limited monochromatic P-polarized light from a solid-state (no gas plasma involved) light source and directed specifically at Brewster'"'"'s angle (principal angle) to form a quasi-elliptical illuminated spot on the material surface which specularly reflects a circular minimal power beam from the surface of the material the cross-section of which has a dark (no-light) central band and two outer low light lobes;
causing a contaminant on the material surface to pass multiple times through the quasi-elliptical illuminated spot incident on the material surface so that the contaminant, on each pass through the illuminated spot, scatters the light in a quasi-hemispherical pattern; and
disposing a high numerical aperture light collector, focused on the center of the quasi-elliptical illuminated spot, above and in close proximity to the material surface so as to redirect essentially all the light scattered (with effectively no secondary redirection) from the contaminant to a detector capable of converting the light collected to an electrical signal proportional to the light intensity.
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Accused Products
Abstract
To locate/size contaminants at the surface of a dielectric or semiconductor material, a P-polarized beam of light from a monochromatic solid-state source is disposed specifically at Brewster'"'"'s angle and focused to form an illuminated quasi-elliptical spot on the surface that produces effectively no reflected or scattered light from the surface. The spot is scanned over the entire surface so as to assure multiple passes of any contaminant through the spot. On each pass through the spot a contaminant will produce scattered light. A novel high numerical aperture reflective or refractive system is disposed above the surface to always view the spot and to collect/redirect the bulk of the contaminant scattered light to a detector. Illumination at Brewster'"'"'s angle combined with the high numerical aperture scattered light collector/redirector maximizes the signal-to-noise ratio from the detector. These core components are packaged with support subsystems as a uniquely compact and portable apparatus.
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Citations
83 Claims
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1. A method for locating/sizing contaminants on a bare, highly polished, and planar surface of a dielectric or semiconductor material, comprising the steps of:
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focusing a coherent beam of diffraction limited monochromatic P-polarized light from a solid-state (no gas plasma involved) light source and directed specifically at Brewster'"'"'s angle (principal angle) to form a quasi-elliptical illuminated spot on the material surface which specularly reflects a circular minimal power beam from the surface of the material the cross-section of which has a dark (no-light) central band and two outer low light lobes; causing a contaminant on the material surface to pass multiple times through the quasi-elliptical illuminated spot incident on the material surface so that the contaminant, on each pass through the illuminated spot, scatters the light in a quasi-hemispherical pattern; and disposing a high numerical aperture light collector, focused on the center of the quasi-elliptical illuminated spot, above and in close proximity to the material surface so as to redirect essentially all the light scattered (with effectively no secondary redirection) from the contaminant to a detector capable of converting the light collected to an electrical signal proportional to the light intensity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. An apparatus for locating/sizing contaminants on a bare, highly polished, and planar surface of a dielectric or semiconductor material comprising:
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means for directing a focused coherent diffraction limited beam of monochromatic P-polarized light from a solid-state (no gas plasma involved) light source and specifically disposed at Brewster'"'"'s angle (principal angle) to form a quasi-elliptical illuminated spot on the material surface that specularly reflects a circular minimal power beam from the material surface the cross-section of which has a dark (no-light) central band and two outer low light lobes;
the center of said illuminated spot coincident with the focal point of the beam on the beam optical axis and on the material surface;a high numerical aperture light collector disposed above and in close proximity with the material surface and focused on the center of the quasi-elliptical illuminated spot on the material surface to maximize capture of quasi-hemispherically scattered light from a contaminant illuminated by the light beam incident on the material surface; and a detector disposed near the exit aperture of the light collector opposite the material surface for generating a signal indicative of the intensity of the scattered light captured by and redirected through the light collector to the detector. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83)
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Specification