Optical measurements of line edge roughness
View Patent ↗A method and system for optical measurements of line edge roughness (LER) of patterned structures based on illuminating the structure with incident radiation and detecting a spectral response of the structure, and further applying software and/or hardware utilities for deriving information representative of said line edge roughness parameter/s from said spectral response of the structure.
1. A method of optical measurements of line edge roughness of patterned structures the method comprising:
illuminating the structure with incident radiation and detecting a spectral response of the structure, applying software and/or hardware utilities for deriving information representative of said line edge roughness from said spectral response of the structure, wherein said hardware utilities comprises a bright field optical arrangement; and
wherein applying of said bright-field optical arrangement further comprises step of blocking more than half of the optical arrangement aperture using a blocking shutter.
2. The method of claim 1 wherein said hardware utilities comprise a dark field optical arrangement.
3. The method of claim 2 wherein said dark field optical arrangement provides said illuminating the structure with normal incident radiation and detecting a scattered spectral response of the structure.
4. The method of claim 2 wherein said dark field optical arrangement provides said illuminating the structure with oblique incident radiation and detecting a normally scattered spectral response of the structure.
5. The method of claim 2 wherein said dark field optical arrangement further comprises a polarizer in an illuminating channel and analyzer in detecting channel, wherein axis of polarization said polarizer and analyzer are substantially mutually perpendicular.
6. The method of claim 1 wherein applying software and/or hardware utilities for deriving information representative of said line edge roughness from said spectral response of the structure comprises a merit function analysis.
7. The method of claim 1 wherein applying software and/or hardware utilities for deriving information representative of said line edge roughnessparameter/s from said spectral response of the structure comprises a spectral error analysis.
8. The method of claim 1 wherein applying softwareand/or hardware utilities for deriving information representative of said line edge roughnessparameter/s from said spectral response of the structure comprises applying a model including an effect of line edge roughness.
9. An optical measurement tool for line edge roughness of patterned structures comprising:
an illuminator for illuminating the structure with incident radiation and a detector for detecting a spectral response of the structure, and software and/or hardware utilities for deriving information representative of said line edge roughness from said spectral response of the structure, wherein said bright field optical arrangement further comprises in optical paths a blocking element for blocking more than half of the optical arrangement aperture.
10. The system of claim 9 wherein said hardware utilities comprises a dark field optical arrangement.
11. The system of claim 9 wherein said hardware utilities comprises a bright field optical arrangement.
12. The system of claim 11 wherein said optical arrangement further comprising in the optical paths a retarding element and a polarizer.
13. The system of claim 9 wherein said blocking element is in the form of an insertable shutter.