Method and system for using reflectometry below deep ultra-violet (DUV) wavelengths for measuring properties of diffracting or scattering structures on substrate work pieces
First Claim
1. A reflectometer apparatus for analyzing a scattering or diffracting structure, comprising:
- a below deep ultra-violet (DUV) wavelength referencing reflectometer configured for normal incidence operation and having a light source that provides light at wavelengths below 190 nm, wherein referencing is configured to account for system and environmental changes to adjust reflectance data obtained through use of the reflectometer; and
at least one computer, which is connected to the reflectometer and is configured to run a computer program which causes the at least one computer to extract structural and optical parameters from a theoretical model of the scattering or diffracting structure,wherein the computer program uses a reduced RCW calculation for analyzing 2-D periodic structures of the scattering or diffracting structure.
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Abstract
A method and apparatus is disclosed for using below deep ultra-violet (DUV) wavelength reflectometry for measuring properties of diffracting and/or scattering structures on semiconductor work-pieces is disclosed. The system can use polarized light in any incidence configuration, but one technique disclosed herein advantageously uses un-polarized light in a normal incidence configuration. The system thus provides enhanced optical measurement capabilities using below deep ultra-violet (DUV) radiation, while maintaining a small optical module that is easily integrated into other process tools. A further refinement utilizes an r-θ stage to further reduce the footprint.
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Citations
26 Claims
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1. A reflectometer apparatus for analyzing a scattering or diffracting structure, comprising:
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a below deep ultra-violet (DUV) wavelength referencing reflectometer configured for normal incidence operation and having a light source that provides light at wavelengths below 190 nm, wherein referencing is configured to account for system and environmental changes to adjust reflectance data obtained through use of the reflectometer; and at least one computer, which is connected to the reflectometer and is configured to run a computer program which causes the at least one computer to extract structural and optical parameters from a theoretical model of the scattering or diffracting structure, wherein the computer program uses a reduced RCW calculation for analyzing 2-D periodic structures of the scattering or diffracting structure. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of optically measuring diffracting and scattering features on a sample, comprising:
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providing an optical signal having at least some light at wavelengths below 190 nm; directing the light on the sample in a substantially normally incident configuration, wherein the incident light is un-polarized; utilizing a reduced RCW calculation to analyze 2-D periodic structures; and utilizing a group theoretic approach to analyze 3-D periodic structures. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method of optically measuring diffracting and scattering features on a sample, comprising:
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providing a reflectometer that utilizes at least some light at wavelengths below 190 nm; measuring intensity data from a plurality of sites within an area of the sample; and analyzing a combination of the measured intensity data from the plurality of sites that is independent of incident intensity in order to extract structural and/or optical property information regarding the sample. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A method of optically measuring diffracting and scattering features on a sample, comprising:
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providing a reflectometer that utilizes at least some light at wavelengths below 190 nm; and measuring intensity data from a plurality of sites within an area of the sample;
wherein at least one of the sites represents an un-patterned region of the sample and at least one other site represents a patterned region of the sample. - View Dependent Claims (22, 23)
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24. A reflectometer apparatus for analyzing a scattering or diffracting structure, comprising:
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a below deep ultra-violet (DUV) wavelength referencing reflectometer configured for normal incidence operation and having an unpolarized light source and non-polarizing optical system that provides light at wavelengths below 190 nm, wherein referencing is configured to account for system and environmental changes to adjust reflectance data obtained through use of the reflectometer; at least one computer, which is connected to the reflectometer and is configured to run a computer program which causes the at least one computer to extract structural and optical parameters from a theoretical model of the scattering or diffracting structure; and an r-θ
stage for holding the scattering or diffracting structure, wherein a calculated reflectance is obtained from a relationship that is independent of a sample rotation. - View Dependent Claims (25, 26)
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Specification