Spectroscopic ellipsometer and ellipsometry
View Patent ↗A spectroscopic ellipsometer has a polarized light generating part for generating elliptically polarized lights of a plurality of wavelengths included in a predetermined measurement wavelength band from white light and directing the elliptically polarized lights to a measurement surface of a substrate, a rotating analyzer where reflected light reflected on the measurement surface enters, and a spectrometer for acquiring spectral intensity of light from the rotating analyzer. A polarization state acquiring part in a control part acquires a polarization state at each wavelength in the measurement wavelength band of the reflected light. The optical characteristic calculation part obtains a film thickness on the measurement surface with high accuracy on the basis of differences between measurement values and theoretical values, the measurement values representing change of a complex amplitude ratio between a p-polarized component and an s-polarized component and a phase difference between a p-polarized component and an s-polarized component.
1. A spectroscopic ellipsometer, comprising:
a light source;
a polarized light generating part for generating a multiple wavelength polarized light directed to an object by acquiring elliptically polarized lights from lights of a plurality of wavelengths, said lights being emitted from said light source, or by acquiring a circularly polarized light from a light of a specific wavelength included in said plurality of wavelengths and acquiring an elliptically polarized light from a light of another wavelength included in said plurality of wavelengths;
a rotating analyzer where a reflected light of said multiple wavelength polarized light enters, said rotating analyzer rotating around a central axis parallel to an optical axis;
a spectrometer for receiving a light directed from said rotating analyzer to acquire spectral intensity; and
a polarization state acquiring part for acquiring a polarization state at each of said plurality of wavelengths of said reflected light on the basis of output of said spectrometer.
2. The spectroscopic ellipsometer according to claim 1 , wherein
said polarized light generating part comprises:
a polarizer for acquiring linearly polarized lights from said lights of said plurality of wavelengths; and
a wave retardation plate for acquiring an elliptically polarized light or a circularly polarized light from each of said linearly polarized lights.
3. The spectroscopic ellipsometer according to claim 2 , further comprising
a calculation part for obtaining a value of at least one optical characteristic of said object on the basis of differences between measurement values in said plurality of wavelengths and theoretical values where said at least one optical characteristic is a variable, said measurement values representing a phase difference between a p-polarized component and an s-polarized component and a complex amplitude ratio between a p-polarized component and an s-polarized component or representing said phase difference between said p-polarized component and said s-polarized component and change of a complex amplitude ratio between a p-polarized component and an s-polarized component in reflection on said object.
4. The spectroscopic ellipsometer according to claim 3 , wherein
said at least one optical characteristic includes a thickness of a film formed on said object or a refractive index of said film.
5. The spectroscopic ellipsometer according to claim 2 , wherein
said polarized light generating part acquires a circularly polarized light from a light of a specific wavelength included in said plurality of wavelengths.
6. The spectroscopic ellipsometer according to claim 2 , wherein
said light source is a white light source, and
said lights of said plurality of wavelengths are included in a predetermined wavelength band out of white light which is emitted from said light source.
7. The spectroscopic ellipsometer according to claim 6 , wherein
a minimum wavelength of said predetermined wavelength band is equal to or larger than 300 nm.
8. The spectroscopic ellipsometer according to claim 1 , wherein
a calculation part for obtaining a value of at least one optical characteristic of said object on the basis of differences between measurement values in said plurality of wavelengths and theoretical values where said at least one optical characteristic is a variable, said measurement values representing a phase difference between a p-polarized component and an s-polarized component and a complex amplitude ratio between a p-polarized component and an s-polarized component or representing said phase difference between said p-polarized component and said s-polarized component and change of a complex amplitude ratio between a p-polarized component and an s-polarized component in reflection on said object.
9. The spectroscopic ellipsometer according to claim 8 , wherein
said at least one optical characteristic includes a thickness of a film formed on said object or a refractive index of said film.
10. The spectroscopic ellipsometer according to claim 8 , wherein
said polarized light generating part acquires a circularly polarized light from a light of a specific wavelength included in said plurality of wavelengths.
11. The spectroscopic ellipsometer according to claim 8 , wherein
said light source is a white light source, and
said lights of said plurality of wavelengths are included in a predetermined wavelength band out of white light which is emitted from said light source.
12. The spectroscopic ellipsometer according to claim 11 , wherein
a minimum wavelength of said predetermined wavelength band is equal to or larger than 300 nm.
13. The spectroscopic ellipsometer according to claim 1 , wherein
said polarized light generating part acquires a circularly polarized light from a light of a specific wavelength included in said plurality of wavelengths.
14. The spectroscopic ellipsometer according to claim 13 , wherein
said light source is a white light source, and
said lights of said plurality of wavelengths are included in a predetermined wavelength band out of white light which is emitted from said light source.
15. The spectroscopic ellipsometer according to claim 14 , wherein
a minimum wavelength of said predetermined wavelength band is equal to or larger than 300 nm.
16. The spectroscopic ellipsometer according to claim 1 , wherein
said light source is a white light source, and
said lights of said plurality of wavelengths are included in a predetermined wavelength band out of white light which is emitted from said light source.
17. The spectroscopic ellipsometer according to claim 16 , wherein
a minimum wavelength of said predetermined wavelength band is equal to or larger than 300 nm.