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US 6,665,112 B2Granted
Optical reticle substrate inspection apparatus and beam scanning method of the same
AssigneeNEC Corporation
InventorMotonari Tateno
Life of this patent
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AssigneeNEC Corporation
InventorMotonari Tateno
Estimating the term…
An optical reticle substrate inspection apparatus is provided with a laser, a first acoustooptical element which scans a laser beam output from the laser, an a second acoustooptical element which generates a virtual image with a concave lens effect to the laser beam output from the first acoustooptical element. The optical reticle substrate inspection apparatus is further provided with a concave lens arranged on the output side of the laser beam of the second acoustooptical element and an optical system which images the virtual image on a reticle substrate being an object to be inspected. The concave lens magnifies the laser beam in a perpendicular direction to the scanning direction by the first acoustooptical element.
A beam scanning method of an optical reticle substrate inspection apparatus, comprising the steps of:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
From the US filing history. Foreign family members aren’t listed.
Inspecting patterns on the surface of objects: patterns showing hole parts, e.g. honeycomb filtering structures
Characterised by the material or shape of the object to be examined: inspecting patterns on the surface of objects
Inspecting patterns on the surface of objects: masks, reticles, shadow masks
Illumination; Optics: electro-optic, magneto-optic, acousto-optic elements
Term ended 29 Nov 2021 (estimated)
1. Field of the Invention
The present invention relates to an optical reticle substrate inspection apparatus that inspects a defect and a line width of a reticle substrate and a beam scanning method thereof, particularly, to an optical reticle substrate inspection apparatus for improving stability when a laser light source having a short wavelength is used and a beam scanning method thereof.
2. Description of the Related Art
FIG. 1 is a schematic view showing a conventional optical reticle substrate inspection apparatus.
FIG. 2 is a schematic view showing a structure of an optical reticle substrate inspection apparatus according to a first embodiment of the present invention.
FIG. 3 is a schematic view showing a beam scanning method of the optical reticle substrate inspection apparatus according to the first embodiment of the present invention.
Preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings as follows. FIG. 2 is a schematic view showing a structure of an optical reticle substrate inspection apparatus according to a first embodiment of the present invention.
In the optical reticle substrate inspection apparatus according to the first embodiment, similarly to the conventional apparatus, the laser light source 1, the acoustooptical element 2 and the group of cylindrical lenses 3 are arranged in this order in the rectilinear direction of the laser beam output from the laser light source 1. A laser wavelength of the laser light source 1 is 300 nm or less, for example. The acoustooptical element 2 is made of quartz, for example, and is arranged so as to scan the laser beam output from the laser light source 1 in a vertical direction to the straight line by the frequency modulation. The group of cylindrical lenses 3 is arranged so as to magnify the laser beam output form the acoustooptical element 2 only in the scanning direction by the acoustooptical element 2. Note that the scanning direction by the acoustooptical element 2 corresponds to the Y-axis direction.
In this embodiment, an acoustooptical element 4 showing the lens effect is further provided for the laser beam output from the group of cylindrical lenses 3. The transducer 19 is attached to one end portion of the acoustooptical element 4. The acoustooptical element 4 is arranged such that a side where the transducer 19 is attached, that is, a side where the ultrasonic is input, is closer to the group of cylindrical lenses 3. Furthermore, in this embodiment, a group of cylindrical concave lenses 5, which magnifies the laser beam output form the acoustooptical element 4 only in a perpendicular direction to the scanning direction and outputs it, is provided. A numerical aperture of the group of cylindrical concave lenses 5 equals a numerical aperture of the acoustooptical element 4 when it functions as the cylindrical concave lens. Therefore, the shape of the virtual image formed by the acoustooptical element 4 and the group of cylindrical concave lenses 5 is the circle.