Detection system for nanometer scale topographic measurements of reflective surfaces
First Claim
1. A detector array configured for use with a light source, comprising:
- a plurality of elements configured to detect a reflected beam of light energy provided by the light source and reflected from a component, said reflected beam following a reflection path and having a beam diameter wherein position of the reflected beam relative to the plurality of elements corresponds to contours of the component, and wherein a portion of the reflected beam is a unitary beam diverted from the reflection path and directed toward the plurality of elements; and
a plurality of electrical connections affixed to said plurality of elements, said plurality of electrical connections connectable to at least one inspection device;
wherein said plurality of elements are linearly arranged elements each having width less than approximately one third the beam diameter, and wherein output from said plurality of elements is weighted to skew information based on beam position.
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Abstract
A linear position array detector system is provided which imparts light energy to a surface of a specimen, such as a semiconductor wafer, receives light energy from the specimen surface and monitors deviation of the retro or reflected beam from that expected to map the contours on the specimen surface. The retro beam will, with ideal optical alignment, return along the same path as the incident beam if and only if the surface is normal to the beam. The system has a measurement device or sensor within the path of the retro or reflected beam to measure deviation of the retro beam from expected. The sensor is preferably a multiple element array of detector-diodes aligned in a linear fashion. A unique weighting and summing scheme is provided which increases the mechanical dynamic range while preserving sensitivity. The system further includes a bright field Nomarski Differential Interference Contrast sensor used to split the beam into two beams and for scanning in an orientation orthogonal to the orientation of the optical lever created by the system.
39 Citations
20 Claims
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1. A detector array configured for use with a light source, comprising:
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a plurality of elements configured to detect a reflected beam of light energy provided by the light source and reflected from a component, said reflected beam following a reflection path and having a beam diameter wherein position of the reflected beam relative to the plurality of elements corresponds to contours of the component, and wherein a portion of the reflected beam is a unitary beam diverted from the reflection path and directed toward the plurality of elements; and a plurality of electrical connections affixed to said plurality of elements, said plurality of electrical connections connectable to at least one inspection device; wherein said plurality of elements are linearly arranged elements each having width less than approximately one third the beam diameter, and wherein output from said plurality of elements is weighted to skew information based on beam position. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for inspecting a specimen, comprising:
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providing light energy to said specimen, thereby creating a retro beam reflected from said specimen; providing said retro beam to a multi-element sensing device comprising a plurality of linearly oriented sensing elements such that said retro beam is received by at least three of said sensing elements; and altering a characteristic of said electrical output according to a weighting corresponding to a distance of said plurality of sensing elements from a predetermined point on said multi-element sensing device. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method for inspecting a surface of a specimen, comprising:
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providing at least three linearly arranged elements having electrical connections to an inspection device and predetermined spacing therebetween; imparting a portion of a light beam received from the surface of the specimen onto said linearly arranged elements by diverting the portion of the light beam from a reflection path, wherein position of the portion of the light beam relative to the linearly arranged elements corresponds to contours on the surface of the specimen; and weighting data received by said linearly arranged elements to skew information based on beam position; wherein said portion of the light beam spans at least three of said linearly arranged elements. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification