Surface inspection method and apparatus therefor
First Claim
1. A method of inspecting a substrate surface having a known reflectivity to detect the diameters of particles on the substrate surface, comprising the steps of:
- irradiating light on said substrate surface,collecting scattered light from said particles,detecting said scattered light collected, andcompensating for detection sensitivity of said scattered light in accordance with a compensation control signal on the basis of intensity of said scattered light from said particles corresponding to reflectivity of said substrate surface so that the particle diameters on the substrates can be detected correctly even when the reflectivities of the substrate surface differ from a standard.
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Accused Products
Abstract
A novel technique suitable for inspection or examination of the surface condition of a substrate such as a semiconductor wafer. First is one irradiates a light e.g. a laser beam on a substrate surface to focus a scattered light therefrom. Next detects the scattered light focused e.g. with a photomultiplier tube, thus to inspect the substrate surface. When the detection of the scattered light is thus carried out, correction means e.g. a circuit for controlling a voltage applied to the photomultiplier tube, a filter having a variable light-screening factor, a movable iris or an amplification factor adjustment circuit etc. is used to correct the detection sensitivity in accordance with the reflectivity of the substrate surface. Practically, such a corrective operation is carried out on the basis of the intensity of a scattered light or a regularly reflected light from the substrate surface. Further, it may be possible to obtain a signal for control of the corrective operation by averaging signals detected when the substrate surface is subject to scanning of an irradiating light. Thus, this surface inspection technique can detect particles attached on the substrate surface always utilizing the same slice level and the same sensitivity even when substrates having different indices of reflection are employed.
61 Citations
17 Claims
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1. A method of inspecting a substrate surface having a known reflectivity to detect the diameters of particles on the substrate surface, comprising the steps of:
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irradiating light on said substrate surface, collecting scattered light from said particles, detecting said scattered light collected, and compensating for detection sensitivity of said scattered light in accordance with a compensation control signal on the basis of intensity of said scattered light from said particles corresponding to reflectivity of said substrate surface so that the particle diameters on the substrates can be detected correctly even when the reflectivities of the substrate surface differ from a standard. - View Dependent Claims (2)
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3. A method of inspecting a substrate surface having a known reflectivity to detect the diameters of particles on the substrate surface, comprising the steps of:
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irradiating light on said substrate surface; collecting scattered light from said substrate surface, detecting said scattered light collected, and compensating for detection sensitivity of said scattered light in accordance with a compensation control signal on the basis of intensity of regularly reflected light from said substrate surface corresponding to reflectivity of said substrate surface so that the particle diameters on the substrates can be detected correctly even when the reflectivities of the substrate surface differ from each other. - View Dependent Claims (4)
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5. An apparatus for inspecting a substrate surface, having a known reflectivity to detect the diameters of particles on the substrate surface, comprising:
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a light source irradiating light on said substrate surface, means for collecting scattered light from said particles, a photomultiplier tube for detecting said scattered light collected by said collecting means, a detector circuit for detecting an amplitude of said scattered light, means for outputting a compensation control signal corresponding to said reflectivity of said substrate surface on the basis of intensity of said scattered light from said substrate surface, and means for compensating for detection sensitivity of said photomultiplier tube in accordance with reflectivity of said substrate surface, so that the particle diameters on the substrates can be detected correctly even when the reflectivities of the substrate surfaces differ from each other. - View Dependent Claims (6, 7, 8, 9, 10)
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11. An apparatus for inspecting a substrate surface having a known reflectivity to detect the diameters of particles on the substrate surface, comprising:
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a light source irradiating light on said substrate surface, means for collecting scattered light from said substrate surface, a photomultiplier tube for detecting said scattered light collected by said collecting means, and a detector circuit for detecting amplitude of said scattered light, means for outputting a compensation control signal corresponding to said reflectivity of said substrate surface on the basis of intensity of a regularly reflected light from said substrate surface, a detector circuit for detecting amplitude of said scattered light, means for compensating a detection sensitivity of said photomultiplier tube in accordance with a reflectivity of said substrate surface, so that the particle diameters on the substrates can be detected correctly even when the reflectivities of the substrate surfaces differ from each other. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification