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JP-7857006-B2 - Spectroscopic ellipsometer

JP7857006B2JP 7857006 B2JP7857006 B2JP 7857006B2JP-7857006-B2

Inventors

  • 森田 恭平

Assignees

  • 株式会社渋谷光学

Dates

Publication Date
20260512
Application Date
20220228

Claims (8)

  1. A mounting platform on which the sample is placed, Light source and An irradiation means that uses light from the light source to irradiate the sample with inspection light directed towards at least two or more target areas, A photodetector that spectrally analyzes and receives the inspection light reflected from at least two of the aforementioned target regions, Equipped with, The irradiation means is a reflective mask or mirror having multiple reflective surfaces corresponding to each of the at least two target areas. A spectroscopic ellipsometer characterized by the following features.
  2. In the spectroscopic ellipsometer according to claim 1, The reflective mask or mirror is positioned such that the at least two target regions and the reflective surfaces corresponding to each of the at least two target regions are in a conjugate relationship. The projection magnification of the inspection light onto the surface of the sample is equal to 1x. A spectroscopic ellipsometer characterized by the following features.
  3. A mounting platform on which the sample is placed, Light source and An irradiation means that uses light from the light source to irradiate the sample with inspection light directed towards at least two or more target areas, A photodetector that spectrally analyzes and receives the inspection light reflected from at least two of the aforementioned target regions, Equipped with, The irradiation means is a transmissive mask having a transmissive surface corresponding to each of the at least two target regions. A spectroscopic ellipsometer characterized by the following features.
  4. In the spectroscopic ellipsometer according to claim 3, The transparent mask is positioned such that the at least two target regions and the transparent surfaces corresponding to each of the at least two target regions are in a conjugate relationship. The projection magnification of the inspection light onto the surface of the sample is equal to 1x. A spectroscopic ellipsometer characterized by the following features.
  5. In the spectroscopic ellipsometer according to any one of claims 1 to 4, The aforementioned sample is a semiconductor wafer, The spectroscopic ellipsometer is characterized in that the target region is a plurality of test pads provided within a region corresponding to a semiconductor chip on a semiconductor wafer.
  6. A mounting platform on which the sample is placed, Light source and An irradiation means that uses light from the light source to irradiate the sample with inspection light directed towards at least two or more target areas, A photodetector that spectrally analyzes and receives the inspection light reflected from at least two of the aforementioned target regions, Equipped with, The aforementioned photodetector is The collimator lens has an optical axis that passes through the intersection of a conjugate plane, which is conjugate to the surface of the sample, and the optical axis of the inspection light reflected from the sample, and is perpendicular to the conjugate plane, and emits the incident inspection light as parallel light. A spectroscopic ellipsometer characterized by the following features.
  7. A mounting platform on which the sample is placed, Light source and An irradiation means that uses light from the light source to irradiate the sample with inspection light directed towards at least two or more target areas, A photodetector that spectrally analyzes and receives the inspection light reflected from at least two of the aforementioned target regions, Equipped with, The aforementioned photodetector is A collimator lens that emits the aforementioned inspection light as parallel light, A prism for spectrally separating the inspection light from the collimator lens, It has, The collimator lens is positioned such that its image field curvature characteristics align with a conjugate plane that is conjugate to the surface of the sample, and the optical axis of the collimator lens is offset from the optical axis of the inspection light. A spectroscopic ellipsometer characterized by the following features.
  8. A mounting platform on which the sample is placed, Light source and An irradiation means that uses light from the light source to irradiate the sample with inspection light directed towards at least two or more target areas, A photodetector that spectrally analyzes and receives the inspection light reflected from at least two of the aforementioned target regions, Equipped with, The aforementioned photodetector is A concave mirror that emits the aforementioned inspection light as parallel light, A prism for spectrally separating the inspection light from the concave mirror, It has, The concave mirror is positioned such that its image field curvature characteristics align with a conjugate plane that is conjugate to the surface of the sample, with the optical axis of the concave mirror offset from the optical axis of the inspection light. A spectroscopic ellipsometer characterized by the following features.

Description

This invention relates to a spectroscopic ellipsometer for measuring, for example, the thickness and optical properties of a thin film on the surface of a semiconductor wafer. Ellipsometry (polarization analysis technique) has long been known as a technique for measuring the optical properties of materials. Ellipsometry measures the change in polarization state when a test light reflects off a material, and determines the material's optical properties from the measured change in polarization state. The change in polarization state is measured as the ratio ρ of the amplitude reflection coefficient rp for p-polarization to the amplitude reflection coefficient rs for s-polarization (amplitude reflection coefficient ratio). The ratio ρ of the amplitude reflection coefficient rp for p-polarization to the amplitude reflection coefficient rs for s-polarization is expressed as ρ = tan(Ψ)・exp(iΔ) using two ellipsometry angles Ψ and Δ. Note that the two ellipsometry angles Ψ and Δ depend on the optical properties of the individual material. Therefore, ellipsometers using ellipsometry are used, for example, in the semiconductor field to measure the optical properties and film thickness of thin films (see Patent Document 1). Patent No. 3716305 This is a schematic diagram showing an example of the configuration of an ellipsometer in the first embodiment.This is an explanatory diagram showing an example of the arrangement of reflective surfaces provided on a mask.This is a plan view of a semiconductor wafer in which multiple chip regions are formed in a two-dimensional manner.(a) is an example of the arrangement of a chip region and test pads provided on a semiconductor wafer, (b) is an example of a chip region in which one of a plurality of test pads arranged in the X-axis direction is offset in the Y-axis direction, and (c) is an explanatory diagram showing an example of a chip region in which one of a plurality of test pads is positioned offset in both the X-axis and Y-axis directions.This is a schematic diagram showing an example of the configuration of a photodetector.This is an explanatory diagram showing an example of collimator lens arrangement when the optical axis of the collimator lens is perpendicular to the conjugate plane and the optical axis of the collimator lens passes through the intersection of the conjugate plane and the optical axis of the reflected light.This is an explanatory diagram showing an example of collimator lens arrangement when the optical axis of the collimator lens is perpendicular to the conjugate plane and the center of the collimator lens is located at [location].This figure shows an example of a photodetector in which a collimator lens is positioned with its optical axis offset from the optical axis of the inspection light, so that its image field curvature characteristics align with a conjugate plane that is conjugate to the surface of the sample.This figure shows an example of a photodetector in which a concave mirror is positioned with its optical axis offset from the optical axis of the inspection light, so that its image field curvature characteristics align with a conjugate surface that is conjugate to the surface of the sample.This figure shows that the inspection light emitted from the mask 16 is irradiated obliquely onto a 1 x 2 mm area on the surface of the sample S.This figure shows the Strehr ratio when the light beam emitted from point P1 to point P9 is focused onto the light-receiving surface, when the optical axis of the collimator lens is offset from the optical axis of the inspection light, in a case where the image field curvature characteristics of the collimator lens are aligned with the conjugate surface that is conjugate to the surface of the sample, and the irradiation angle θ at which the inspection light is irradiated onto the surface of the sample is θ = 50°, and inspection light with wavelengths λ = 365, 436, 588, 656, 707, and 1014 nm is used.This figure shows the Strehr ratio when the light beam emitted from point P1 to point P9 is focused onto the light-receiving surface, when the optical axis of the collimator lens is offset from the optical axis of the inspection light, in a case where the image field curvature characteristics of the collimator lens are aligned with the conjugate surface that is conjugate to the surface of the sample, and the irradiation angle θ at which the inspection light is irradiated onto the surface of the sample is θ = 55°, and inspection light with wavelengths λ = 365, 436, 588, 656, 707, and 1014 nm is used.This figure shows the Strehr ratio when the light beam emitted from point P1 to point P9 is focused onto the light-receiving surface, when the optical axis of the collimator lens is offset from the optical axis of the inspection light, with the image field curvature characteristics of the collimator lens aligned with the conjugate surface that is conjugate to the surface of the sample, and when the irradiation angle θ at w