The present invention provides an ellipsometry device and an ellipsometry method whereby measurement efficiency can be enhanced. In this method, an object is illuminated by spherical-wave-like illumination light Q linearly polarized at 45° (S1), and an object light O, being a reflected light, is acq
The present invention provides an ellipsometry device and an ellipsometry method whereby measurement efficiency can be enhanced. In this method, an object is illuminated by spherical-wave-like illumination light Q linearly polarized at 45° (S1), and an object light O, being a reflected light, is acquired in a hologram IOR using a spherical-wave-like reference light R having a condensing point near the condensing point of the illumination light Q, and a hologram ILR of the reference light R is furthermore acquired using a spherical-wave reference light L having the same condensing point as that of the illumination light Q (S2). The holograms are separated into p- and s-polarized light holograms IKOR, IKLR, κ=p, s and processed to extract object light waves, and object light spatial frequency spectra GK(u, v), κ=p, s are generated (S3) (S4). Ellipsometric angles ψ(θ), Δ(θ) are obtained for each incident angle θ from the amplitude reflection coefficient ratio ρ=Gp/Gs=tan ψ·exp(iΔ). Through use of numerous lights having different incident angles θ included in the illumination light Q, data of numerous reflection lights can be acquired collectively in a hologram and can be processed.
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1. An ellipsometry device used for polarization analysis of a light emitted from an object, comprising: a data acquisition unit which acquires data of an object light (O) emitted from the object illuminated by a non-parallel illumination light (Q) of known polarization state containing p- and s-pola
1. An ellipsometry device used for polarization analysis of a light emitted from an object, comprising: a data acquisition unit which acquires data of an object light (O) emitted from the object illuminated by a non-parallel illumination light (Q) of known polarization state containing p- and s-polarized lights as an object light hologram (IOR) using an off-axis reference light (R) so that the object light hologram (IOR) is separable into p- and s-polarization holograms, and acquires data of the off-axis reference light (R) as a reference light hologram (ILR) using an in-line spherical-wave reference light (L) so that the reference light hologram (ILR) is separable into p- and s-polarization holograms; anda data analysis unit which performs polarization analysis of the object light (O), whereinthe data analysis unit comprises:a light wave reconstruction unit which generates light wave holograms (gK(x, y), κ=p, s) expressing each light wave of p- and s-polarized lights in the object light (O), respectively, on a hologram plane using the data of the object light hologram (IOR) and the reference light hologram (ILR) acquired by the data acquisition unit;an object light plane wave expansion unit which generates object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization by performing plane wave expansion on each of the light wave holograms (gK(x, y), κ=p, s) of p- and s-polarization, respectively;a polarization coefficient generation unit which generates an illumination light polarization coefficient (ξQ=Ss(u, v)/Sp(u, v)) being a ratio of an illumination light spatial frequency spectrum (Ss(u, v)) of an s-polarized light in the illumination light (Q) to an illumination light spatial frequency spectrum (Sp(u, v)) of a p-polarized light in the illumination light (Q) on the hologram plane using known information of the illumination light (Q); andan operation unit which derives, using the object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization and the illumination light polarization coefficient (ξQ), an amplitude reflection coefficient ratio (ρ=rp/rs=ξQGp(u, v)/Gs(u, v)) being a ratio of an amplitude reflection coefficient (rp=Gp(u, v)/Sp(u, v)) of p-polarization to an amplitude reflection coefficient (rs=Gs(u, v)/Ss(u, v)) of s-polarization, for each spatial frequency (u, v). 2. The ellipsometry device according to claim 1, wherein the data acquisition unit comprises:an optical system which generates the illumination light (Q) in a spherical-wave-like state, the off-axis reference light (R) in a spherical-wave-like state, and the in-line spherical-wave reference light (L), with a coherent light emitted by a laser, and propagates the generated lights;a photo-detector which changes a light intensity into an electric signal and outputs it;a storage unit which stores the object light hologram (IOR) being an off-axis hologram of interference fringes between the object light (O) and the off-axis reference light (R), and the reference light hologram (ILR) being an off-axis hologram of interference fringes between the in-line spherical-wave reference light (L) and the off-axis reference light (R), in a memory by acquiring them through the photo-detector; anda polarization setting unit which is provided on a light path from the laser to the photo-detector and sets the polarization state of light propagating on the light path so that each of the object light hologram (IOR) and the reference light hologram (ILR) can be acquired and stored in the storage unit as a hologram separable into p- and s-polarization holograms, whereinthe data analysis unit comprises:a polarization separation unit which generates object light holograms (IKOR, κ=p, s) of p- and s-polarization separated from the object light hologram (IOR) for each polarization, respectively, and reference light holograms (IKLR, κ=p, s) of p- and s-polarization separated from the reference light hologram (ILR) for each polarization, respectively; anda make-in-line unit which generates object light complex amplitude in-line holograms (JKOL, κ=p, s) of p- and s-polarization, respectively, by eliminating the component of the off-axis reference light (R) from the object light holograms (IKOR, κ=p, s) of p- and s-polarization and the reference light holograms (IKLR, κ=p, s) of p- and s-polarization, whereinthe light wave reconstruction unit generates the light wave holograms (gK(x, y), κ=p, s) of p- and s-polarization, respectively, by eliminating the component of the in-line spherical-wave reference light (L) from the object light complex amplitude in-line holograms (JKOL, κ=p, s) of p- and s-polarization generated by the polarization separation unit and the make-in-line unit, using the characteristics as spherical-wave light of the in-line spherical-wave reference light (L). 3. The ellipsometry device according to claim 2, wherein the polarization setting unit comprises a reference light dividing unit which divides the off-axis reference light (R) into a p-polarized off-axis reference light (Rp) and an s-polarized off-axis reference light (Rs) so that they are mutually off-axis, whereinthe data acquisition unit acquires the object light hologram (IOR) and the reference light hologram (ILR), so that each of the holograms is separable into p- and s-polarization holograms, using and superposing the p- and s-polarized off-axis reference lights (RK, κ=p, s) obtained by the reference light dividing unit. 4. The ellipsometry device according to claim 3, wherein the reference light dividing unit divides the off-axis reference light (R) into the p- and s-polarized lights using a Wollaston prism. 5. The ellipsometry device according to claim 2, wherein the photo-detector is a CCD, andthe polarization setting unit comprises a polarizer array for setting the polarization state of the light received by the photo-detector for every pixel of the CCD. 6. An ellipsometry method used for polarization analysis of a light emitted from an object, comprising the steps of: acquiring data of an object light (O) emitted from the object illuminated by a non-parallel illumination light (Q) of known polarization state containing a p-polarized light and an s-polarized light as an object light hologram (IOR) using an off-axis reference light (R) so that the object light hologram (IOR) is separable into p- and s-polarization holograms, and acquiring data of the off-axis reference light (R) as a reference light hologram (ILR) using an in-line spherical-wave reference light (L) so that the reference light hologram (ILR) is separable into p- and s-polarization holograms;generating light wave holograms (gK(x, y), κ=p, s) expressing each light wave of p- and s-polarized lights in the object light (O), respectively, on a hologram plane using the data of the object light hologram (IOR) and the reference light hologram (ILR);generating object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization by performing plane wave expansion on each of the light wave holograms (gK(x, y), κ=p, s) of the p- and s-polarization lights, respectively;generating an illumination light polarization coefficient (ξQ=Ss(u, v)/Sp(u, v)) being a ratio of an illumination light spatial frequency spectrum (Ss(u, v)) of an s-polarized light in the illumination light (Q) to an illumination light spatial frequency spectrum (Sp(u, v)) of a p-polarized light in the illumination light (Q) on the hologram plane using known information of the illumination light (Q); andderiving, using the object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization and the illumination light polarization coefficient (ξQ), an amplitude reflection coefficient ratio (ρ=rp/rs=ξQGp(u, v)/Gs(u, v)) being a ratio of an amplitude reflection coefficient (rp=Gp(u, v)/Sp(u, v)) of p-polarized light to an amplitude reflection coefficient (rs=Gs(u, v)/Ss(u, v)) of s-polarized light, for each spatial frequency (u, v). 7. The ellipsometry method according to claim 6, wherein generating the illumination light (Q) in a spherical-wave-like state, the off-axis reference light (R) in a spherical-wave-like state, and the in-line spherical-wave reference light (L) with a coherent light emitted by a laser, and propagating the generated lights;acquiring and storing the object light hologram (IOR) being an off-axis hologram of interference fringes between the object light (O) and the off-axis reference light (R), and the reference light hologram (ILR) being an off-axis hologram of interference fringes between the in-line spherical-wave reference light (L) and the off-axis reference light (R);generating object light holograms (IKOR, κ=p, s) of p- and s-polarization and reference light holograms (IKLR, κ=p, s) of p- and s-polarization separated for each polarization from the object light hologram (IOR) and the reference light hologram (ILR), respectively;generating object light complex amplitude in-line holograms (JKOL, κ=p, s) of p- and s-polarization, respectively, by eliminating the component of the off-axis reference light (R) from the object light holograms (IKOR, κ=p, s) of p- and s-polarization and the reference light holograms (IKLR, κ=p, s) of p- and s-polarization; andgenerating the light wave holograms (gK(x, y), κ=p, s) of p- and s-polarization, respectively, by eliminating the component of the in-line spherical-wave reference light (L) from the object light complex amplitude in-line holograms (JKOL, κ=p, s) of p- and s-polarization, using the characteristics as spherical-wave light of the in-line spherical-wave reference light (L). 8. The ellipsometry method according to claim 7, wherein the acquisition of each of the object light hologram (IOR) and the reference light hologram (ILR) is performed by dividing the off-axis reference light (R) in the spherical-wave-like state into a p-polarized off-axis reference light (Rp) and an s-polarized off-axis reference light (Rs) so that they are mutually off-axis and by superimposing the p- and s-polarized off-axis reference lights (RK, κ=p, s) mutually,the separation of each of the object light hologram (IOR) and the reference light hologram (ILR) into p- and s-polarization holograms is performed by a filtering based on the fact that the off-axis reference lights (RK, κ=p, s) of p- and s-polarization are mutually off-axis. 9. The ellipsometry method according to claim 7, wherein the acquisition of each of the object light hologram (IOR) and the reference light hologram (ILR) is performed by using a CCD, being a photo detector, alternately equipped with a polarizer for s-polarization and a polarizer for p-polarization for every pixel of the CCD, andthe separation of each of the object light hologram (IOR) and the reference light hologram (ILR) into p- and s-polarization holograms is performed by separating data for every pixel of the CCD into data of p- and s-polarization. 10. The ellipsometry method according to claim 6, wherein the object light hologram (IOR) and the reference light hologram (ILR) are acquired by using two or more coherent lights of different wavelength overlapped mutually, andthe amplitude reflection coefficient ratio (ρ=rp/rs) is derived for each of the different wavelengths. 11. The ellipsometry method according to claim 6, wherein the amplitude reflection coefficient ratio (ρ=rp/rs) is derived after transforming each of the object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization and the illumination light spatial frequency spectra (SK(u, v), κ=p, s) of p- and s-polarization into an expression, respectively, on a plane parallel to a surface of the object by a coordinate rotation transform. 12. The ellipsometry method according to claim 7, wherein the object light hologram (IOR) is acquired using a spherical-wave light as the illumination light (Q), andthe reference light hologram (ILR) is acquired using the illumination light (Q) as the in-line spherical-wave reference light (L) by reflecting the illumination light (Q) of spherical-wave light onto the hologram plane using a reflector of known reflective characteristic for polarized light. 13. The ellipsometry method according to claim 6, wherein the acquisition of the object light hologram (IOR) is performed by setting a size of illuminated spot with the illumination light (Q) on a surface of the object as a size for microscopic observation, andthe processing for generating the object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization comprises the steps of:substantially increasing a sampling point number for each of the light wave holograms (gK(x, y), κ=p, s) of p- and s-polarization by subdividing a spatial sampling interval and performing a data interpolation to a new sampling point produced by the subdividing;dividing each of the light wave holograms of p- and s-polarization having the increased sampling point number into a plurality of minute holograms (gKi(x, y), κ=p, s), respectively;generating each of synthetic minute holograms (ΣK(x, y), κ=p, s) of p- and s-polarization by mutually superimposing each of the minute holograms (gKi(x, y), κ=p, s) generated by the dividing, for p- and s-polarization respectively; andgenerating each of the object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization by performing a plane wave expansion on each of the synthetic minute holograms (ΣK(x, y), κ=p, s) of p- and s-polarization, whereineach of reconstructed light waves (hK(x, y), κ=p, s) of p- and s-polarization of the object light (O) at a position where the optical axis of the object light (O) intersects the surface of the object is generated using spatial frequencies (u, v, w) satisfying the dispersion relation of a plane wave and the object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization generated through the increasing of the sampling point number,each of rotated reconstructed light waves (bK(x′, y′), κ=p, s) of p- and s-polarization of the object light (O) is generated by transforming each of the reconstructed light waves (hK(x, y), κ=p, s) of p- and s-polarization into an expression on a plane parallel to the surface of the object by a coordinate rotation transform, respectively, andthe amplitude reflection coefficient ratio (ρ=ξQbp(x′, y′)/bs(x′, y′)) at each of the points (x′, y′) in the illuminated spot or an image (|bK|2, κ=p, s) of the surface of the object for the microscopic observation is derived using the illumination light polarization coefficient (ξQ), and the rotated reconstructed light waves (bK(x′, y′), κ=p, s) of p- and s-polarization. 14. The ellipsometry method according to claim 6, comprising the steps of: acquiring an angle (α) between a surface of the object and the hologram plane;acquiring the object light hologram (IOR) by illuminating the object with an incident angle of the illumination light (Q) involving the Brewster angle (θB) of the object;deriving the amplitude reflection coefficient ratio (ρ) after transforming each of the object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization and the illumination light spatial frequency spectra (SK(u, v), κ=p, s) of p- and s-polarization into an expression, respectively, on a plane parallel to the surface of the object by a coordinate rotation transform using the angle (α) between the surface of the object and the hologram plane;deriving ellipsometric angles (ψ, Δ) for the polarization analysis from the amplitude reflection coefficient ratio (ρ) on a plurality of incident angles involved in the illumination light (Q);deriving a value of a refractive index (n) of the object reflecting the illumination light (Q) by fitting the ellipsometric angles (ψ, Δ) with model curves having the incident angle (θ) as a variable and the refractive index (n) as a parameter. 15. The ellipsometry method according to claim 6, wherein the acquisition of the object light hologram (IOR) is performed by using the illumination light (Q) being made spherical-wave-like and by illuminating large surface of the object including a plurality of measurement points with the illumination light (Q), wherein the condensing point of the illumination light (Q) is arranged at the front or rear of the large surface, andthe derivation of the amplitude reflection coefficient ratio (ρ) is performed on each point of the plurality of the measurement points. 16. The ellipsometry method according to claim 6, wherein the acquisition of the object light hologram (IOR) is performed by using the illumination light (Q) being made spherical-wave-like and by arranging the condensing point of the illumination light (Q) on the surface of the object. 17. The ellipsometry method according to claim 7, wherein the object light hologram (IOR) and the reference light hologram (ILR) are acquired by using two or more coherent lights of different wavelength overlapped mutually, andthe amplitude reflection coefficient ratio (ρ=rp/rs) is derived for each of the different wavelengths. 18. The ellipsometry method according to claim 8, wherein the object light hologram (IOR) and the reference light hologram (ILR) are acquired by using two or more coherent lights of different wavelength overlapped mutually, andthe amplitude reflection coefficient ratio (ρ=rp/rs) is derived for each of the different wavelengths. 19. The ellipsometry method according to claim 7, wherein the amplitude reflection coefficient ratio (ρ=rp/rs) is derived after transforming each of the object light spatial frequency spectra (GK(u, v), κ=p, s) of p- and s-polarization and the illumination light spatial frequency spectra (SK(u, v), κ=p, s) of p- and s-polarization into an expression, respectively, on a plane parallel to a surface of the object by a coordinate rotation transform. 20. The ellipsometry method according to claim 8, wherein the object light hologram (IOR) is acquired using a spherical-wave light as the illumination light (Q), andthe reference light hologram (ILR) is acquired using the illumination light (Q) as the in-line spherical-wave reference light (L) by reflecting the illumination light (Q) of spherical-wave light onto the hologram plane using a reflector of known reflective characteristic for polarized light.
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