JP4260683B2 - Ellipsometer, polarization state acquisition method and light intensity acquisition method - Google Patents

Description

  The present invention relates to a technique for obtaining a polarization state of light from an object by irradiating the object with polarized light, and a method for obtaining the intensity of light emitted from a rotating rotating polarizing element.

  Conventionally, an ellipsometer has been used to measure the thickness, optical constant, and the like of a film formed on a semiconductor substrate (hereinafter referred to as “substrate”). An ellipsometer performs various measurements by irradiating polarized light onto a substrate to acquire the polarization state of the reflected light and performing polarization analysis. In such an ellipsometer, the effects of the optical elements that make up the ellipsometer on the polarization state of the reflected light, such as an optical system that guides the reflected light from the object and a photodetector that receives the reflected light to acquire the polarization state, are suppressed. Various techniques for doing so have been proposed.

For example, Patent Document 1 discloses a technique for suppressing an influence due to polarization characteristics of a photodetector by providing an optical fiber on an optical path from an object to the photodetector. There is also known a technique in which an element such as a depolarization plate is arranged on the optical path to suppress the influence of the optical element on the polarization state.
Japanese Patent Laid-Open No. Sho 62-266439

  By the way, in the ellipsometer of Patent Document 1, since an optical fiber having a length of about 1 m to 10 m or more is provided, the structure of the apparatus becomes complicated. In addition, the attenuation of the amount of light by the optical fiber is large, and the time required for measurement increases. Furthermore, the reproducibility of measurement values and measurement accuracy may be reduced due to the influence of the ambient temperature on the optical fiber. Similarly, when an element such as a depolarizing plate is used, there are problems such as a complicated configuration of the ellipsometer and a decrease in reproducibility of measurement values and measurement accuracy.

  The present invention has been made in view of the above problems, and an object of the present invention is to obtain information used for polarization analysis with high accuracy while simplifying the configuration of an ellipsometer.

  The invention according to claim 1 is an ellipsometer, and includes an irradiation unit that guides polarized light to an object, and an axis in which reflected light of the polarized light from the object is incident and that faces an optical axis direction. A detection-side rotating polarizer that rotates as a center, a detection optical system that receives light that has passed through the rotating polarizer, a sensor that receives light that has passed through the detection optical system and detects the intensity of the light, An arithmetic unit that corrects the intensity detected by the sensor based on the rotation angle of the rotating polarizer and the reflection amplitude ratio angle of the detection optical system and obtains the intensity of light immediately after passing through the rotating polarizer. With.

According to a second aspect of the present invention, in the ellipsometer according to the first aspect, the calculation unit is configured such that the rotation angle of the rotating polarizer from a predetermined reference posture is θ, and the reflection amplitude ratio angle of the detection optical system. Ψ _det , the intensity detected by the sensor as I (θ), and the intensity I ₀ (θ) of light immediately after passing through the rotating polarizer,

Ask for.

  The invention according to claim 3 is the ellipsometer according to claim 1 or 2, wherein an optical element is disposed only between the rotary polarizer and the sensor on an optical path from the object to the sensor. Is done.

  The invention according to claim 4 is the ellipsometer according to any one of claims 1 to 3, wherein the detection optical system includes a spectroscopic element, and the light immediately after passing through the rotary polarizer by the arithmetic unit. The intensity for each wavelength is required.

  The invention described in claim 5 is the ellipsometer according to claim 4, wherein the spectroscopic element is a diffraction grating type spectroscopic element.

  The invention according to claim 6 is a polarization state acquisition method for irradiating an object with polarized light to acquire the polarization state of the light from the object, and irradiating the object with polarized light. The reflected light of the polarized light from the object and the object is received by a sensor via a rotating polarizer and a detection optical system that rotate about an axis that faces the optical axis direction, and the intensity of the received light is detected. Correcting the intensity detected by the sensor based on the detection step, the rotation angle of the rotary polarizer, and the reflection amplitude ratio angle of the detection optical system, and the light immediately after passing through the rotary polarizer And a calculation step for obtaining the strength.

The invention according to claim 7 is a light intensity acquisition method for obtaining the intensity of light immediately after passing through the rotating rotating polarizer, and the light incident on the rotating polarizer along the rotation axis of the rotating polarizer. , Based on the detection step of detecting the intensity of the light received by the sensor through the detection optical system from the rotary polarizer, the rotation angle of the rotary polarizer, and the reflection amplitude ratio angle of the detection optical system A calculation step of correcting the intensity detected by the sensor and obtaining the intensity of light immediately after passing through the rotary polarizer, wherein in the calculation step, the rotation angle of the rotary polarizer from a predetermined reference posture Is θ, the reflection amplitude ratio angle of the detection optical system is ψ _det , the intensity detected by the sensor is I (θ), and the intensity I ₀ (θ) of light immediately after passing through the rotating polarizer is

Is required.

  In the present invention, information used for polarization analysis can be acquired with high accuracy while simplifying the configuration of the apparatus. In the invention of claim 2, information used for the polarization analysis can be easily obtained, and in the invention of claim 3, the information used for the polarization analysis can be obtained with higher accuracy.

  According to the fourth aspect of the present invention, it is possible to acquire the intensity for each wavelength of the light immediately after passing through the rotating polarization element without being affected by the polarization characteristics of the detection optical system that differs for each wavelength. In the invention of claim 5, even when the detection optical system includes a diffraction grating type spectroscopic element that easily affects the polarization state of light, the polarization state can be detected with high accuracy.

  In the invention of claim 7, the intensity of light immediately after passing through the rotating polarizing element can be obtained with high accuracy.

  FIG. 1 is a diagram showing a configuration of an ellipsometer 1 according to an embodiment of the present invention. The ellipsometer 1 is an apparatus that performs polarization analysis by irradiating polarized light onto a semiconductor substrate 9 (hereinafter referred to as “substrate 9”), and measuring the polarization state of reflected light from the substrate 9.

  The ellipsometer 1 includes a stage 2 that supports a substrate 9, a stage moving mechanism 21 that moves the stage 2 in the X and Y directions in FIG. 1, a stage elevating mechanism 24 that raises and lowers the stage 2 in the Z direction in FIG. Irradiating unit 3 that guides the light (hereinafter referred to as “polarized light”) onto the substrate 9, a light receiving unit 4 that receives reflected light of the polarized light from the substrate 9, and a control unit 5 that controls these configurations. The control unit 5 includes a calculation unit 51 that performs various calculation processes and a storage unit 52 that stores various types of information.

  The stage moving mechanism 21 includes a Y direction moving mechanism 22 that moves the stage 2 in the Y direction, and an X direction moving mechanism 23 that moves in the X direction. The Y-direction moving mechanism 22 is configured such that a ball screw (not shown) is connected to the motor 221, and the X-direction moving mechanism 23 moves along the guide rail 222 in the Y direction in FIG. 1 as the motor 221 rotates. Move to. The X-direction moving mechanism 23 has the same configuration as the Y-direction moving mechanism 22. When the motor 231 rotates, the stage 2 moves in the X direction along the guide rail 232 by a ball screw (not shown).

  The irradiation unit 3 is a light source unit 31 having a high-intensity xenon (Xe) lamp that emits light for polarization analysis, and a polarizer (a so-called polarizer) that is a polarizing element on which light from the light source unit 31 is incident. 32, the light from the light source unit 31 is converted into linearly polarized light by the polarizer 32 and irradiated onto the substrate 9. The light source unit 31 may be composed of other types of lamps.

  The light receiving unit 4 is an analyzer 41 that is a rotating polarizing element (a so-called rotating analyzer) on which reflected light from the substrate 9 is incident, a spherical mirror 421 whose surface is made of aluminum (Al), and a flat mirror. 422, a lens 423, and a spectroscope 43. The analyzer 41 has an optical axis parallel to the principal ray of the reflected light from the substrate 9, and rotates around an axis that faces the optical axis direction. The spectroscope 43 includes a spectroscopic element 432 that is a diffraction grating type optical element that splits incident light for each wavelength (for example, for each wavelength from ultraviolet rays to near infrared rays), and the intensity of light for each light receiving position, that is, And an optical sensor 431 for detecting the intensity for each wavelength of received light (hereinafter referred to as “received light”).

  In the light receiving unit 4, the reflected light from the substrate 9 enters the spherical mirror 421 through the analyzer 41, and is received by the optical sensor 431 through the mirror 422, the lens 423, and the spectroscopic element 432. Hereinafter, the spherical mirror 421, the mirror 422, the lens 423, and the spectroscopic element 432 on which light having passed through the analyzer 41 is incident are collectively referred to as a detection optical system 42.

  In the ellipsometer 1, these components are controlled by the control unit 5, and the intensity of light immediately after being reflected by the substrate 9 and passing through the analyzer 41 (hereinafter referred to as “analyzer passing light”) is obtained. Note that the polarization state of light immediately before entering the analyzer 41 (that is, the amplitude ratio angle and the phase difference between the p-polarized component and the s-polarized component) is obtained by acquiring the intensity of the analyzer-passing light at each rotation angle of the analyzer 41. Will be acquired.

  FIG. 2 is a diagram showing a flow of operation of the ellipsometer 1. When measurement is performed by the ellipsometer 1, first, the position of the substrate 9 supported by the stage 2 is adjusted by the stage moving mechanism 21 and the stage elevating mechanism 24 (step S11). The polarized light is irradiated on the top (step S12). The polarized light is reflected by the substrate 9, and in the light receiving unit 4, the reflected light from the substrate 9 is collected by the lens 423 via the analyzer 41, the spherical mirror 421 and the mirror 422, and guided to the spectroscopic element 432. The light is split by 432 with high wavelength resolution and received by the optical sensor 431. The optical sensor 431 measures the intensity for each wavelength of the received light at each rotation angle of the analyzer 41 with good sensitivity while rotating the analyzer 41, and outputs the measurement result to the control unit 5 (step S13).

  By the way, in the ellipsometer 1, the light that has passed through the analyzer 41 passes through the detection optical system 42 and is received by the optical sensor 431 while being influenced by the polarization characteristics of the detection optical system 42. For this reason, the intensity of the received light detected by the optical sensor 431 for each wavelength (hereinafter referred to as “measurement intensity”) is different from the intensity of the analyzer-passing light at that wavelength.

3 to 7 are diagrams showing the relationship between the reflection characteristic of the substrate 9 (that is, the change in the polarization state when comparing the light incident on the substrate and the light reflected by the substrate) and the wavelength. is there. 3 to 7 show an irradiation part 3 on a substrate 9 on which a single layer film of silicon oxide (SiO ₂ ) having a thickness of 1 nm (nanometer), 10 nm, 50 nm, 100 nm, and 500 nm is formed. It is the figure which calculated | required the reflection characteristic of the board | substrate 9 when light injects with the incident angle of 65 degree | times by simulation.

  The solid lines 811 to 815 and solid lines 821 to 825 in FIGS. 3 to 7 are the theoretical reflection amplitude ratio angle Ψ (degrees) and the theoretical (that is, determined based on the analyzer passing light) of the substrate 9, respectively. The phase difference Δ (degree) is shown, and the broken lines 831 to 835 and the broken lines 841 to 845 indicate the reflection amplitude ratio of the substrate 9 when the light after passing through the detection optical system 42 is obtained as the analyzer passing light. Angle Ψ and phase difference Δ are shown. The broken lines 831 to 835 and the broken lines 841 to 845 are the results of a simulation performed on the assumption that the detection optical system 42 includes only the spherical mirror 421 and the mirror 422, and light is incident on both mirrors. The angle is 30 degrees.

FIG. 8 is a diagram showing the reflection characteristics of aluminum forming the spherical mirror 421 and the mirror 422 used in the simulation. A line 801 in FIG. 8 represents tan (Ψ _mir ), where Ψ _mir is a reflection amplitude ratio angle when light is incident on an aluminum mirror at an incident angle of 30 degrees. As shown in FIG. 8, when the wavelength of the light incident on the mirror is about 800 nm, tan (Ψ _mir ) is about 0.98.

  As described above, in the light passing through the analyzer and the light after passing through the detection optical system 42, the polarization characteristic of the detection optical system 42 (change in the polarization state of the light when passing through the optical element as well as the reflection characteristic of the mirror). As a result, the light intensity is shifted, and as a result, the required reflection characteristics of the substrate 9 are also shifted as shown in FIGS. In particular, a relatively large shift occurs in the vicinity where the phase difference Δ is 180 degrees. In the actual ellipsometer 1, the detection optical system 42 includes the lens 423 and the spectroscopic element 432 in addition to the spherical mirror 421 and the mirror 422, so that the light intensity deviation due to the polarization characteristics of the detection optical system 42 is further increased.

Here, when linearly polarized light having an amplitude of 1 is reflected by a mirror having a complex reflectance of the p-polarized component of r _pmir and a complex reflectance of the s-polarized component of r _smir , the p-polarized component of the reflected light Ex And the s-polarized component Ey, the angle between the vibration direction of linearly polarized light and the incident surface of the mirror is β (degrees), the reflection amplitude ratio angle and the phase difference of the mirror are Ψ _mir (degrees), Δ _mir (degrees), It is expressed by Equation 5. However, r _pmir and r _{smir in the} second and subsequent lines of _Equation 5 indicate coefficients after separating the phase difference.

Therefore, the intensity I _re of the reflected light when the intensity of the linearly polarized light incident on the mirror is I _in can be expressed by Equation 6. Here, the constant α is a constant obtained by Equation 7.

In the ellipsometer 1, in order to accurately determine the polarization state of the light immediately before entering the analyzer 41, the detection optical system 42 is assumed to be a mirror in the description of Equation 5, and based on the relationships shown in Equations 5 to 7, The change in the polarization state by the detection optical system 42 is corrected. In the ellipsometer 1, the rotation angle of the analyzer 41 from a predetermined reference posture is θ (degrees), the reflection amplitude ratio angle for each wavelength of the detection optical system 42 is Ψ _λdet (degrees), and the measured intensity for each wavelength of the received light is I As (θ) _λ , the intensity I ₀ (θ) _{λ for} each wavelength of the analyzer-passing light is obtained by Equation 8.

Here, the reflection amplitude ratio angle Ψ _{λdet for} each wavelength of the detection optical system 42 is the reflection amplitude ratio angle at the wavelength of the spherical mirror 421, mirror 422, lens 423, and spectroscopic element 432 that are components of the detection optical system 42. When the reflection amplitude ratio angles of the spherical mirror 421, the mirror 422, the lens 423, and the spectroscopic element 432 are Ψ _λ1 to Ψ _λ4 , they are obtained by Equation 9 and acquired and controlled in advance by a method described later. It is stored in the storage unit 52 of the unit 5.

  The reference posture of the analyzer 41 (that is, the posture where θ is 0 degree) refers to the direction of the vibration direction of the analyzer passing light that has been linearly polarized by the analyzer 41 and the reference surface of the detection optical system 42 (for example, bent). The posture when the angle formed with the surface including the optical axis) is 0 degree, that is, the analyzer passing light within the virtual incident surface when the detection optical system 42 is regarded as one virtual reflecting surface. This is the attitude of the analyzer 41 when vibrating. In the ellipsometer 1, the posture of the analyzer 41 that passes the p-polarized component of the reflected light from the substrate 9 is set as a reference posture.

More precisely, the right side of _Equation 8 is (1 / α _λ ) times (where the constant α _λ is the reflection amplitude ratio angle of the detection optical system 42 when the reflectance of the s-polarized component of the virtual surface is _{rs λ.} the using [psi _Ramudadet, a constant determined by the number 10.) but is the, since the constant alpha _lambda does not affect the final measurement result, alpha _lambda as shown in Equation 8 in the actual operation Is ignored.

In the control unit 5, the relationship shown in Equation 8 is stored in advance in the storage unit 52, the rotation angle θ of the analyzer 41 acquired by the control unit 5, and the detection optical system 42 stored in the storage unit 52 in advance. Based on the reflection amplitude ratio angle Ψ _λdet for each wavelength, the measurement intensity I (θ) _{λ for} each wavelength of the received light detected by the optical sensor 431 is corrected by the calculation unit 51, and the analyzer 41 at each rotation angle of the analyzer 41. The intensity (hereinafter referred to as “correction intensity”) I ₀ (θ) _{λ of} each wavelength of the passing light is obtained (step S14).

  9 shows the measured intensity of the received light and the corrected intensity of the light passing through the analyzer when polarized light having a wavelength of 600 nm is incident on the substrate 9 on which a single layer film of silicon oxide having a thickness of 58 nm is formed. It is a figure shown in comparison for every rotation angle. A solid line 851 in FIG. 9 represents a value (hereinafter referred to as “relative measurement intensity”) obtained by dividing the measurement intensity of the received light at each rotation angle by the average value of the measurement intensity in the entire range of θ. A broken line 852 indicates a value obtained by dividing the correction intensity of the analyzer passing light obtained by correcting the measurement intensity of the received light by the calculation unit 51 by the average value of the correction intensity in the entire range of θ (hereinafter, “relative correction intensity”). .)

In the ellipsometer 1, the analyzer 41 calculates (for example, by Fourier transform) the analyzer 41 based on the correction intensity I ₀ (θ) _{λ for} each wavelength of the analyzer passing light or the relative correction intensity obtained for each wavelength. The polarization state for each wavelength of light immediately before entering the light is obtained, and the reflection characteristic for each wavelength of the substrate 9 is obtained (step S15).

FIG. 10 shows the reflection characteristic (that is, the corrected reflection characteristic) of the substrate 9 obtained by the calculation unit 51 based on the corrected intensity I ₀ (θ) _λ and the calculated intensity I (θ) _λ. It is a figure which compares and shows the reflection characteristic (namely, reflection characteristic before correction | amendment) of the board | substrate 9 in the case of a case.

  The solid lines 861 and 862 in FIG. 10 indicate the reflection amplitude ratio angle Ψ and the phase difference Δ that represent the reflection characteristics of the substrate 9 before correction, and the broken lines 863 and 864 indicate the reflection characteristics of the substrate 9 after correction. The reflection amplitude ratio angle Ψ and the phase difference Δ are shown. For example, when the wavelength of light is 600 nm, the reflection amplitude ratio angle Ψ and the phase difference Δ before correction are 30.1 degrees and 106.4 degrees, respectively, and the reflection amplitude ratio angle Ψ and the phase difference Δ after correction are They are 27.8 degrees and 106.9 degrees, respectively. In the ellipsometer 1, the change in the polarization state by the detection optical system 42 is corrected by the correction by the calculation unit 51, the reflection characteristic of the substrate 9 is obtained, and the polarization analysis is performed.

Note that the calculation unit 51 of the ellipsometer 1 uses the relative measurement intensity I ₀ (λ _{0 λrel} ) as the relative measurement intensity I ₀ ( _λ ) for each wavelength obtained from the measurement intensity I (θ) _λ for each wavelength of the received light. θ) _λrel may be obtained by _Equation 11, and in this case, the reflection characteristic of the substrate 9 is obtained based on the relative correction intensity I ₀ (θ) _λrel .

Further, in the ellipsometer 1, by making the reflection amplitude ratio angle _Ψλdet of the detection optical system 42 close to 45 degrees, it is possible to reduce the deviation of the polarization state by the detection optical system 42 and to reduce the correction amount by the calculation unit 51. .

FIG. 11 shows an operation of acquiring the reflection amplitude ratio angle Ψ _λdet for each wavelength of the detection optical system 42 used for calculating the correction intensity I ₀ (θ) _λ for each wavelength of the analyzer passing light (step S14). FIG. The operation of obtaining the reflection amplitude ratio angle Ψ _λdet is normally performed when the ellipsometer 1 is manufactured.

In the ellipsometer 1, first, a substrate 9 on which a single-layer film having a known thickness is formed is prepared (step S 21), and a polarizer is provided in front of the analyzer 41 on the optical path between the substrate 9 and the analyzer 41. It is installed in a direction (usually a direction in which the polarization direction of the polarizer is inclined by 45 degrees with respect to the incident surface of the substrate 9) (step S22), and the amplitude ratio angle of the light incident on the analyzer 41 is the same at all wavelengths. Is done. Here, the amplitude ratio angle _ψide of the light incident on the analyzer 41 is obtained by calculation (step S23).

Next, measurement by the ellipsometer 1 is performed, and the measured intensity I (θ) _λ after passing through the detection optical system 42 is acquired by the optical sensor 431, and the amplitude ratio angle ψ of the light after passing through the detection optical system 42 _λmeas is obtained (step S24). Then, the amplitude ratio angle [psi _ide, based on [psi _meas, reflection amplitude ratio angle [psi _Ramudadet optical imaging system 42 is determined by the number 12 (step S25). Thereby, the reflection amplitude ratio angle Ψ _λdet can be easily obtained.

Figure 12 is a diagram showing the reflection amplitude ratio angle [psi _Ramudadet optical imaging system 42, a line 871 in FIG. 12, the light incident on the detection optical system 42 and the reflection amplitude ratio angle [psi _Ramudadet optical imaging system 42 The relationship with wavelength is shown. In the ellipsometer 1, the reflection amplitude ratio angle Ψ _λdet of the detection optical system 42 acquired by the above-described acquisition operation is stored in the storage unit 52 of the control unit 5 to calculate the correction intensity I ₀ (θ) _λ of the analyzer passing light. Used for

In the ellipsometer 1, with respect to a substrate having a known film thickness, the amplitude ratio angle ψ _λmeas obtained from the measured intensity I (θ) _{λ of the} received light, and the amplitude ratio angle ψ of the light immediately before entering the analyzer 41 obtained by calculation. Based on _λies , the reflection amplitude ratio angle _{Ψλdet of the} detection optical system 42 may be obtained by _Expression 12.

  As described above, the ellipsometer 1 does not require a new optical element (for example, an optical fiber or a depolarization plate) for suppressing the influence of the detection optical system 42 on the light reflected from the substrate 9. The configuration of the apparatus can be simplified, the influence on the apparatus configuration due to external factors such as ambient temperature can be reduced, and the reproducibility of the measured intensity detected by the optical sensor 431 can be improved.

In the ellipsometer 1, it is possible to correct the influence of the detection optical system 42 disposed between the analyzer 41 and the optical sensor 431 and to obtain the correction intensity of the analyzer passing light with high accuracy. As a result, the polarization state of the reflected light from the substrate 9, that is, the information used for the polarization analysis of the substrate 9 can be obtained with high accuracy. At this time, the reflection amplitude ratio angle Ψ _λdet of the detection optical system 42 is acquired in advance, and the correction intensity of the analyzer passing light is obtained based on the relationship shown in _Equation 8, so that information used for polarization analysis can be easily obtained. Can be acquired.

  In the ellipsometer 1, an optical element such as the detection optical system 42 is arranged only between the analyzer 41 and the optical sensor 431 on the optical path from the substrate 9 to the optical sensor 431 (that is, between the substrate 9 and the analyzer 41. An optical element is not disposed between them.) The influence of the polarization characteristics of all the optical elements (except the analyzer 41) through which the reflected light from the substrate 9 reaches the optical sensor 431 can be corrected. Information used for ellipsometry can be acquired with higher accuracy.

In the ellipsometer 1, the correction intensity of the analyzer passing light is obtained by the calculation unit 51 based on the reflection amplitude ratio angle Ψ _λdet for each wavelength of the detection optical system 42, and therefore the detection optical system 42 that differs for each wavelength of incident light. The correction intensity for each wavelength of the analyzer passing light can be acquired without being affected by the polarization characteristic. As a result, information used for polarization analysis can be obtained with high accuracy even for a substrate having a multilayer film formed on the surface.

  Further, since the ellipsometer 1 can correct the influence of the detection optical system 42 with high accuracy, even if the detection optical system 42 includes a diffraction grating type spectroscopic element 432 that easily affects the polarization state of light. The polarization state for each wavelength of light immediately before entering the analyzer 41 can be detected with high accuracy.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various change is possible.

  For example, the spectroscopic element 432 need not be limited to a diffraction grating type optical element, and various other types of spectroscopic elements may be used. The light source unit 31 of the irradiation unit 3 may be provided with a semiconductor laser that emits a single-wavelength light beam instead of the xenon (Xe) lamp. In this case, the light receiving unit 4 replaces the spectroscope 43. A photodiode or the like is provided.

  The light receiving unit 4 of the ellipsometer 1 is preferably configured such that no optical element is disposed between the substrate 9 and the analyzer 41 on the optical path from the substrate 9 to the optical sensor 431. Even when an optical element is disposed between them, the reflection characteristic of the substrate 9 can be obtained with higher accuracy by correcting the measurement intensity of the received light as described above as compared with the case where the correction is not performed. .

  The substrate 9 is not limited to a semiconductor substrate, and may be, for example, a glass substrate used for a liquid crystal display device or other flat panel display device. Furthermore, the measurement object by the ellipsometer 1 may be a film formed on an object other than the substrate on which the fine pattern is formed.

  Moreover, the method of calculating | requiring the intensity | strength of the light immediately after passing through the rotating rotating polarizer using the relationship shown in Formula 8 can be utilized for apparatuses other than an ellipsometer.

It is a figure which shows the structure of the ellipsometer which concerns on one embodiment. It is a figure which shows the flow of operation | movement of an ellipsometer. It is a figure which shows the relationship between the reflective characteristic of a board | substrate, and the wavelength of incident light. It is a figure which shows the relationship between the reflective characteristic of a board | substrate, and the wavelength of incident light. It is a figure which shows the relationship between the reflective characteristic of a board | substrate, and the wavelength of incident light. It is a figure which shows the relationship between the reflective characteristic of a board | substrate, and the wavelength of incident light. It is a figure which shows the relationship between the reflective characteristic of a board | substrate, and the wavelength of incident light. It is a figure which shows the reflective characteristic of an aluminum mirror. It is a figure which compares and shows a measurement intensity | strength and correction | amendment intensity | strength. It is a figure which compares and shows the polarization characteristic of the detection optical system before and behind correction | amendment. It is a figure which shows the flow of the acquisition operation | work of the reflection amplitude ratio angle of a detection optical system. It is a figure which shows the relationship between the reflection amplitude ratio angle of a detection optical system, and the wavelength of incident light.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ellipsometer 3 Irradiation part 9 Board | substrate 41 Analyzer 42 Detection optical system 51 Calculation part 431 Optical sensor 432 Spectroscopic element S11-S15, S21-S25 Step

Claims (7)

An ellipsometer,
An irradiator that guides polarized light to the object;
A rotating polarizer on the detection side that rotates around an axis that is reflected by the reflected light of the polarized light from the object and that faces the optical axis direction;
A detection optical system on which light having passed through the rotating polarizer is incident;
A sensor that receives light via the detection optical system and detects the intensity of the light;
An arithmetic unit that corrects the intensity detected by the sensor based on the rotation angle of the rotating polarizer and the reflection amplitude ratio angle of the detection optical system and obtains the intensity of light immediately after passing through the rotating polarizer. When,
An ellipsometer characterized by comprising: The ellipsometer according to claim 1, wherein
The calculation unit sets the rotation angle of the rotating polarizer from a predetermined reference posture as θ, the reflection amplitude ratio angle of the detection optical system as Ψ _det , and the intensity detected by the sensor as I (θ), The light intensity I ₀ (θ) immediately after passing through the rotating polarizer is

An ellipsometer characterized by the following. The ellipsometer according to claim 1 or 2,
An ellipsometer, wherein an optical element is disposed only between the rotary polarizer and the sensor on an optical path from the object to the sensor. The ellipsometer according to any one of claims 1 to 3,
The detection optical system includes a spectroscopic element;
An ellipsometer characterized in that an intensity for each wavelength of light immediately after passing through the rotating polarizer is obtained by the arithmetic unit. The ellipsometer according to claim 4, wherein
An ellipsometer, wherein the spectroscopic element is a diffraction grating type spectroscopic element. A polarization state acquisition method of irradiating a target with polarized light to acquire a polarization state of light from the target,
An irradiation step of irradiating polarized light on the object;
A detection step of detecting the intensity of the received light by receiving the reflected light of the polarized light from the object with a sensor via a rotating polarizer and a detection optical system that rotate about an axis that faces the optical axis direction When,
A calculation step of correcting the intensity detected by the sensor based on the rotation angle of the rotating polarizer and the reflection amplitude ratio angle of the detection optical system to obtain the intensity of light immediately after passing through the rotating polarizer. When,
A polarization state acquisition method comprising: A light intensity acquisition method for determining the intensity of light immediately after passing through a rotating rotating polarizer,
A detection step of detecting the light incident on the rotary polarizer along the rotation axis of the rotary polarizer with a sensor from the rotary polarizer via a detection optical system and detecting the intensity of the light;
An arithmetic step of correcting the intensity detected by the sensor based on the rotation angle of the rotating polarizer and the reflection amplitude ratio angle of the detection optical system to obtain the intensity of light immediately after passing through the rotating polarizer. When,
With
In the calculation step, the rotation angle of the rotating polarizer from a predetermined reference posture is θ, the reflection amplitude ratio angle of the detection optical system is Ψ _det , and the intensity detected by the sensor is I (θ), The light intensity I ₀ (θ) immediately after passing through the rotating polarizer is

The light intensity acquisition method characterized by being calculated | required by.

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