High speed laser scanning inspection system
AssigneeApplied Materials Israel Ltd.
InventorDaniel Some
Life of this patent
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Abstract
An optical inspection system rapidly evaluates a substrate by illumination of an area of a substrate larger than a diffraction-limited spot using a coherent laser beam by breaking temporal or spatial coherence. Picosecond or femtosecond pulses from a modelocked laser source are split into a plurality of spatially separated beamlets that are temporally and/or frequency dispersed, and then focused onto a plurality of spots on the substrate. Adjacent spots, which can overlap by up to about 60-70 percent, are illuminated at different times, or at different frequencies, and do not produce mutually interfering coherence effects. Bright-field and dark-field detection schemes are used in various combinations in different embodiments of the system.
Claims14
An apparatus for optical inspection, comprising a beam manipulator for converting a pulsed beam into a plurality of spatially separated beamlets that are incident on a substrate to be inspected, wherein at least some of said beamlets are directed towards different spots on said substrate, wherein centers of at least two of said different spots are spaced apart by no more than about 3 spot diameters, and wherein there is substantially no mutual interference between said beamlets.
An apparatus for optical inspection, comprising:
- a coherent light source producing a pulsed beam;
- a beam manipulator for converting said pulsed beam into a plurality of spatially separated beamlets that are incident on a substrate to be inspected, wherein at least some of said beamlets are directed towards different spots on said substrate, wherein there is substantially no mutual interference between said beamlets;
- a scanner for displacing said beamlets across said substrate;
- and at least one detector that is positioned such as to detect at least two of said beamlets that are reflected from said substrate.
A method of optical inspection, comprising:
- emitting a pulsed beam of coherent light;
- converting said beam into a plurality of spatially separated beamlets;
- impinging said beamlets onto a substrate to be inspected, wherein each of said beamlets responsively to said step of converting illuminates a different spot on said substrate, wherein centers of at least two instances of said different spot are spaced apart by no more than about 3 spot diameters, and there is substantially no mutual interference between said beamlets that illuminate adjacent instances of said different spot on said substrate;
- displacing said beamlets across said substrate;
- and detecting reflected light of said beamlets that is reflected from said substrate.
An Apparatus for optical inspection, comprising;
- a coherent light source producing a pulsed beam;
- a wavelength beam converter for dividing said beam into a plurality of spatially separated beamlets that are incident on a substrate to be inspected, each of said beamlets having a different waveband and illuminating a different spot on said substrate, wherein centers of at least two instances of said different spot are spaced apart by no more than about 3 spot diameters;
- a scanner for displacing said beamlets across said substrates;
- and
- a detector disposed in a path of reflected light from said substrate of said beamlets, wherein said wavelength beam converter comprises a plurality of reflective edge filters.
An Apparatus for optical inspection, comprising;
- a coherent light source producing a pulsed beam;
- a wavelength beam converter for dividing said beam into a plurality of spatially separated beamlets that are incident on a substrate to be inspected, each of said beamlets having a different waveband and illuminating a different spot on said substrate, wherein centers of at least two instances of said different spot are spaced apart by no more than about 3 spot diameters;
- a scanner for displacing said beamlets across said substrates;
- and
- a detector disposed in a path of reflected light from said substrate of said beamlets, wherein said wavelength beam converter comprises a prism.
Dependencies are inferred from the claim text.