Apparatus for optical inspection of a working surface having a dynamic reflective spatial attenuator
OwnerTuan Leinventor
Life of this patent
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Abstract
A dynamic reflective spatial attenuator for use in an optical inspection apparatus. The attenuator takes the form of a two-dimensional micro-mechanical reflective array that, in the first operative position of a mirror element, reflects the desired scattered light toward a detector and, in the second operative position of a mirror element, reflects undesired scattered light into a light dump. The mirror array's fast response and flexibility allows for changes during mid-scan to increase the defect's or contaminant's signal relative to the substrate surface's signal.
Claims25
An optical surface inspection apparatus for determining the presence of unknown surface conditions on a target surface, comprising:
- illumination means for generating an incidence light beam;
- scanning means for scanning the light beam across the target surface, whereby the target surface scatters light in the presence of the light beam;
- light collection means for collecting scattered light, said light collection means comprises:
- (a) detector means for detecting light;
- (b) a dynamic reflective spatial attenuator receiving scattered light from the target surface;
- (c) control means for controlling the dynamic reflective spatial attenuator to obtain an attenuation pattern that selectively diverts light to the detector means;
- discriminating means for determining the presence of unknown surface conditions based on the light detected by the detector means.
A process of inspecting a specimen to determine the presence of unknown surface conditions on a target surface, comprising the steps:
- scanning an incidence light beam across the target surface, whereby the target surface scatters light in the presence of the light beam;
- collecting scattered light by applying a dynamic reflective spatial attenuator to obtain an attenuation pattern that selectively diverts light to a detector;
- determining the presence of unknown surface conditions based on the light detected by the detector means.
Dependencies are inferred from the claim text.