JP2956688B1 - Anisotropic thin film evaluation method and evaluation apparatus - Google Patents

Abstract

A method and apparatus for measuring a dielectric constant and a film thickness of a thin film having optical anisotropy by orienting molecules constituting the thin film are realized. SOLUTION: Parallel light of linearly polarized light is condensed by a lens so as to be focused on the surface of a sample to be incident light on a thin film formed on a substrate, and the generated reflected light is passed through the lens to re-enter. After the light is expanded and passed through the polarizer, the intensity of each of the S-polarized light component and the P-polarized light component is measured by changing the incident direction to the sample, and the reflected light depends on the incident angle of the light incident on the thin film. By measuring the intensity or the anisotropy of the polarization state of the reflected light, the molecular orientation of the thin film,
The dielectric constant, the direction and thickness of the main dielectric constant coordinate, and the dielectric constant and thickness of the non-oriented portion are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for evaluating an anisotropic thin film, and more particularly to an optical anisotropic film used for a liquid crystal display device, in which molecules such as a liquid crystal alignment film for giving initial alignment to liquid crystal molecules are aligned. The present invention relates to a method and an apparatus for evaluating an anisotropic thin film having anisotropy.

[0002]

2. Description of the Related Art Various methods described below have been proposed as methods for evaluating anisotropic thin films.

Japanese Patent Application Laid-Open No. 05-005699 and Japanese Patent Application Laid-Open No. 04-329333 measure the incident angle dependence of the intensity of reflected light generated when a plurality of wavelengths are incident.

Japanese Patent Application Laid-Open No. 03-065637: Dependence of reflected light intensity on incident angle and incident direction is measured.

Japanese Patent Application Laid-Open No. 08-152307: Linearly polarized incident light is condensed using a lens, and the incident angle and the incident angle of the reflected light intensity due to the incident light having only the S-polarized component and the P-polarized component. Measure orientation dependence.

Japanese Patent Application Laid-Open No. 09-218133: A sample is rotated in a plane, and from the dependency of the polarization state of reflected light on the incident azimuth, the dielectric constant, the film thickness, and the direction of the main dielectric constant coordinate of the oriented part are determined.
Determine the dielectric constant and film thickness of the non-oriented part.

[0007] Of these, Japanese Patent Application Laid-Open No. 08-15 / 08
No. 2307, linearly polarized incident light is condensed using a lens, and S-polarized light component and the incident angle of the reflected light intensity when the incident light having only the P-polarized light component is condensed by the lens; In addition, it has an excellent feature that it can be efficiently measured by measuring the incident azimuth dependency and has high spatial resolution.

In the method of condensing incident light with a lens, FIG.
As shown in FIG. 1A, since light passing through a portion near the periphery of the lens 101 has a larger incident angle with respect to the sample 102, a lens having a large numerical aperture and a short focal length is used. A large angle dispersion can be realized for the incident angle.

Further, the reflected light is converted into parallel rays by the same lens as used for condensing the incident light, and is measured by a one-dimensional or two-dimensional photodetector. To show the dependence of the light intensity on the incident angle,
By using a detector having a high positional resolution, it is possible to measure the dependency of the reflected light intensity on the incident angle with high accuracy even in a minute area, and a high spatial resolution is realized.

According to the method disclosed in the above publication, the S-wave component of incident light and P
Utilizing that the incident angle dependence of the reflection intensity of the wave component depends on the refractive index and the film thickness of the film, linearly polarized light is incident on the condenser lens. At this time, the light incident on the lens in the radial direction parallel to the polarization direction has only the P-polarized component when entering the sample, and the light incident on the sample from the radial direction perpendicular to this is the S-polarized component. Has only Therefore, by measuring the reflected light intensity in these two directions, the incident angle dependence of the reflected light intensity of the S-polarized light component and the P-polarized light component is measured. When the thin film has anisotropy, by rotating the polarization direction of the linearly polarized light of the incident light, the direction of the S-polarized light and the P-polarized light incident on the sample is changed to measure the incident direction dependence. Do.

When the thin film is isotropic, or even when the thin film is anisotropic, two of the three principal permittivity coordinate axes are parallel to the film surface, that is, one axis is on the film surface. When perpendicular, the reflected light becomes only the S-polarized component when the S-polarized component is incident, and becomes only the P-polarized component when the P-polarized component is incident. Therefore, the function to measure the polarization state of the reflected light is necessary. And not. However, when the main dielectric constant coordinate system is inclined with respect to the film surface, the reflected light is
Since it has both polarization components, it is not possible to accurately measure the state of the thin film only by measuring the reflected light intensity.

Further, in the invention disclosed in Japanese Patent Application Laid-Open No. 08-152307, light is incident on a lens via a half mirror. In this case, only an S-polarized component or a P-polarized component is applied to the half mirror. Except when the reflected light is incident only, the reflected light does not preserve the polarization state of the incident light, so that the azimuthal anisotropy cannot be measured accurately.

On the other hand, the anisotropic dielectric constant and the film thickness are determined by rotating the sample in a plane and measuring the incident azimuth dependence of the polarization state of the reflected light as disclosed in JP-A-09-218133. In the method, the anisotropic dielectric constant and thickness of the anisotropic film whose main dielectric constant coordinate is inclined with respect to the film surface, and the inclination of the main dielectric constant with respect to the film surface can be determined. It is difficult to improve the spatial resolution. Also,
In the case of uniaxial anisotropy and the optical axis is perpendicular to the sample surface, the anisotropic dielectric constant and the film thickness cannot be determined because the incident azimuth anisotropy is not observed.

As a method for measuring an anisotropic film having a high spatial resolution, there is an invention proposed in Japanese Patent Application No. 09-100330. In the present invention, monochromatic light of a certain polarization state is condensed by a lens, reflected light from the sample surface is converted into parallel rays by the same lens, and reflected using a position detector and a polarizer or a polarizer and a phase plate. The incident angle and the incident azimuth dependence of the polarization state of light are measured. However, in this method, the measurement light is passed through a lens to be condensed and converted into a parallel light beam. At this time, the polarization state of the incident light and the reflected light changes. In particular, since the amplitude ratio between the S-polarized light and the P-polarized light changes, the measurement accuracy is reduced. Therefore, in order to perform accurate measurement, a plurality of standard samples having clear optical characteristics such as optical glass are required. Since it is necessary to carefully calibrate the measurement result of the polarization state by using the same substrate as the standard sample and without the film, simple measurement cannot be performed.

[0015]

Generally, since the complex permittivity of a substance has wavelength dependence, the anisotropic refractive index (dielectric constant) is determined from the measurement of the incident angle dependence of the reflected light intensity at a plurality of wavelengths.
Is difficult to apply except for a sample whose wavelength dispersion characteristic of dielectric constant is known.

A method proposed to obtain an anisotropic dielectric constant and a film thickness of a sample from measurement of the incident angle of reflected light intensity and the incident azimuth, which has been proposed so far, is disclosed in Japanese Patent Application Laid-Open No. 08-15230.
In the method of collecting incident light using a lens disclosed in Japanese Patent Application Laid-Open No. 7-107, when the dielectric constant coordinate is inclined with respect to the film surface, the reflected light contains both the S-polarized component and the P-polarized component. In addition, when light is incident on the lens via the half mirror, the reflected light from the half mirror does not preserve the polarization state of the incident light, so that the azimuthal anisotropy cannot be measured accurately, and the thin film has a different shape. There is a problem that the anisotropic dielectric constant cannot be determined accurately.

Further, it is known that a rubbed polyimide film, which is widely used as an alignment film in a liquid crystal display element, is not oriented in the entire film, but is oriented only in the vicinity of the surface (see Sawa et al., Japanese Journal). Japanese Journal of Applied Physic
s 33, 6273, 1994). For samples with a two-layer structure of anisotropic and isotropic parts with unknown thickness, such as a rubbed liquid crystal alignment film, the anisotropic dielectric constant must be determined by the conventional method. Can not.

On the other hand, in the method disclosed in Japanese Patent Application Laid-Open No. 08-152307, in which the anisotropic dielectric constant is determined from the incident azimuth dependence of the polarization state of reflected light, the thickness of the liquid crystal alignment film is reduced as in a rubbed liquid crystal alignment film. It is possible to measure the anisotropic dielectric constant of a sample having a two-layer structure of an unknown anisotropic part and an isotropic part, the thickness of each part, and the inclination of the main dielectric constant coordinate with respect to the surface. However, when the incident light is condensed, a minute portion cannot be evaluated because a distribution occurs at the incident angle.
Further, in the case of a film whose optical axis is perpendicular to the surface, there is no incident azimuth dependency, so that anisotropic dielectric constant of the film cannot be determined. In the method proposed in Japanese Patent Application No. 09-100330 for evaluating a minute portion using light condensed by a lens, there is a change in the polarization state due to the lens, and the calibration operation is carefully performed to improve the accuracy. Since it is necessary, there is a problem that the measurement is troublesome.

The present invention has been made in view of the above-mentioned problems of the prior art, and is directed to a sample whose main dielectric constant is inclined with respect to the sample surface and a sample whose main dielectric constant is perpendicular to the sample surface. However, it is an object of the present invention to realize a method and an apparatus capable of quickly evaluating the anisotropic dielectric constant and film thickness of a minute portion and the inclination of a main dielectric constant coordinate.

[0020]

The method of evaluating anisotropic thin film according to the present invention is directed to a method of converging linearly polarized parallel light with a lens so as to focus on a sample surface, and then inputting the light to a thin film formed on a substrate. After passing through the lens and expanding the reflected light again by passing the generated reflected light through the polarizer, measuring the intensity of each of the S-polarized component and the P-polarized component is performed by changing the incident direction to the sample. Then, by measuring the reflected light intensity or the anisotropy of the polarization state of the reflected light depending on the incident angle of light incident on the thin film, the molecular orientation of the thin film, the dielectric constant, the orientation of the main dielectric constant coordinate , And thickness, and the dielectric constant and thickness of the non-oriented portion are obtained.

In this case, the incident light may be bent by a half mirror and made incident on the thin film, and the respective intensities of the S-polarized light component and the P-polarized light component of the reflected light from the thin film passing through the half mirror may be measured. .

The anisotropy of the reflected light intensity may be measured by rotating the half mirror.

Also, a half distance between the half mirror and the lens is used.
A wave plate may be inserted, and the anisotropy of the polarization state of the reflected light may be measured by rotating the half-wave plate. In any of the above cases, an analyzer is inserted between the detector and the lens for measuring the intensities of the S-polarized light component and the P-polarized light component, and the analyzer is rotated. The observation may be used to measure the polarization state of the reflected light.

The anisotropic thin film evaluation apparatus of the present invention comprises a light source for generating measurement light that is parallel light of linearly polarized light, a stage on which a sample to be measured is mounted, and the measurement light in a direction toward the sample on the stage. A half mirror to be bent; a lens provided between the half mirror and the sample;
Wave plate, a photodetector that measures the intensity distribution of the reflected light reflected by the sample and passing through the half mirror, and an analyzer provided between the half mirror and the photodetector. An arithmetic unit for determining the dielectric constant and the orientation of the main dielectric constant coordinate, and the thickness of the molecular orientation portion of the thin film according to the detection content of the photodetector, and the dielectric constant and thickness of the non-orientation portion, The lens focuses the measurement light on the surface of the sample, converts the reflected light into parallel rays again, and causes the reflected light to enter the half mirror.

In this case, the stage is configured to be rotatable about the optical axis of the measurement light incident on the sample, and the arithmetic unit determines the reflected light based on the detection content of the photodetector when the stage is rotated. By measuring the anisotropy of the strength, according to the result, the molecular orientation of the thin film, the dielectric constant, the direction of the main dielectric constant coordinate, and the thickness, as to determine the dielectric constant and thickness of the non-oriented portion Is also good.

The half mirror is configured to be rotatable around the optical axis of the measurement light incident on the sample, and the arithmetic unit reflects the light based on the detection content of the photodetector when the half mirror rotates. The light intensity anisotropy is measured, and the dielectric constant, the direction of the main dielectric constant coordinate, and the thickness of the molecular orientation part of the thin film, and the dielectric constant and the thickness of the non-oriented part are determined according to the result. It may be.

The half-wave plate is rotatable about the optical axis of the measurement light incident on the sample, and the arithmetic unit detects the light when the half-wave plate rotates. The anisotropy of the reflected light intensity is measured according to the detection content of the detector, and according to the result, the dielectric constant of the molecular orientation part of the thin film, the direction of the main dielectric constant coordinate, and the thickness, and the dielectric constant of the non-orientation part And the thickness may be determined.

In any of the above cases, the analyzer is configured to be rotatable about the optical axis of the measurement light incident on the sample, and the arithmetic unit is configured to detect the light when the analyzer rotates. The polarization state of the reflected light may be measured by observing the correlation between the rotation angle and the detected intensity according to the detection content of the detector.

[Operation] In the present invention, a part of the light having a fixed polarization state of only the S-polarized component or only the P-polarized component is bent by a half mirror, and passes through a lens in which the polarization state does not change due to passage. To focus on the sample surface. Then, of the reflected light magnified by the same lens, the polarization state of the reflected light generated by the incident light on the sample is changed to a polarizer or a polarizer and a quarter-wave plate, or a one-dimensional or two-dimensional position. Using a detector, measure the incident azimuth and incident angle dependence of the polarization state by rotating the azimuth-variable half-wave plate provided between the lens and the half mirror, or by rotating the azimuth of the half mirror. In this way, the measurement is performed.

In the present invention configured as described above, the anisotropic dielectric constant of the minute part is obtained even for a sample whose main dielectric constant is inclined with respect to the sample surface or a sample whose main dielectric constant is perpendicular to the sample surface. And the inclination of the film thickness and the main dielectric constant coordinate can be evaluated. The principle is described below.

The polarization state of the reflected light is 4 × 4 matrix (Bellman et al., Physical Review Letters, Vol. 25, p. 577, 1970: DW Berrman and TJ Scheffer, Ph.
yscal Review Letters, 25, 577 (1970)). According to this method, when light is incident on the sample at an incident angle β, the states of incident light, reflected light, and transmitted light to the substrate are represented by Φ _I , Φ _r , Φ _t , respectively. The relationship between the 4 × 4 matrix of the alignment layer, the film thickness L ₂ , d ₂ and the 4
Using the × 4 matrix and the film thicknesses L ₁ and d ₁ , Φt = exp (id ₁ L ₁ ) exp (id ₂ L ₂ ) (Φ _I + Φ _r ). Delta ₁₄ in _{L 1, Δ 24, Δ 31} , Δ 32, Δ 33, Δ
_41, delta ₄₂ ,, and, delta _{4 4} is 0, the _{remainder, Δ 11 = - (ε e} - ε o) sinβsinθ cosθ sinΦ / (ε e cos 2 q +
ε _o sin ² q) Δ ₁₂ = 1- sin ² β / (ε _e cos ² θ + ε _o sin ² θ) Δ ₁₃ = (ε _e −ε _o ) sin β sin θ cosθ cosΦ / (ε _e cos ² θ +
ε _o sin ² θ) Δ ₂₁ = ε _o [ε _e- (ε _e -ε _o ) sin ² θ cos ² Φ] / (ε _e cos ² θ +
ε _o sin ² θ) Δ ₂₂ = -ε _e (ε _e -ε _o ) sin ² θ cos ² f / (ε _e cos ² θ + ε _o s
in ² θ) Δ ₂₃ = -ε _o (ε _e -ε _o ) sinθ cosΦsinΦ / (ε _e cos ² θ +
ε _o sin ² θ) Δ ₃₄ = 1 Δ ₄₃ = ε _o [ε _e- (ε _e -ε _o ) sin ² θ sin ² f] / (ε _e cos ² θ +
ε _o sin ² θ) -sin ² β. In this equation, ε _e ε _o is the permittivity expressed in the main permittivity coordinate system, θ is the inclination angle of the main permittivity coordinate with respect to the film surface,
Φ is the in-plane azimuth of the incident light. Since L ₂ is ε _e = ε _o , by replacing them with the dielectric constant ε, Δ ₁₁ ,
Δ _22, Δ _13, Δ ₂₃ becomes 0, Δ ₁₂ = 1- obtain _{^{sin 2 β / ε Δ 21 =}} ε Δ 34 = 1 Δ 43 = ε-sin 2 β. By solving the above equation, the polarization state of the reflected light can be obtained. According to this equation, the phase difference and amplitude of the S-wave component parallel to the sample surface and the P-wave component perpendicular to the traveling direction of the light and orthogonal to the S-wave component are both found for the light incident on the sample. Changes before and after reflection, S
The polarization state and intensity of the reflected light represented by the amplitude of the wave component and the P-wave component and the phase difference between each other are:
It can be seen that it depends on the thickness and the refractive index of the substrate.
Therefore, by measuring the polarization state and the angle dependence of the intensity of the reflected light, the film thickness and the refractive index of the sample can be determined.

In the measurement of the film thickness and the refractive index of a spatially minute portion, the incident light is condensed by a lens to reduce the area of the sample surface where the incident light hits, and the reflected light is again reflected by the lens. This can be achieved by a BPR (Beam Profile Reflectometry) method in which the intensity profile is measured by a position detector after being converted into parallel rays, the incident angle dependence of the reflected light intensity is determined, and the film thickness and the refractive index are calculated.

In the conventional BPR method, an optically isotropic thin film is measured, but only an analyzer (a quarter-wave plate and a polarizer, or a polarizer) is inserted in front of the detector. By measuring the intensities of the S-wave component and the P-wave component of the reflected light, an optically anisotropic film that produces reflected light in which the S-polarized component and the P-polarized component are mixed can be measured.

As an example, the S component and the P component of the reflected light generated when light having only the S-polarized component is incident on the anisotropic film at a specific incident angle are respectively Rss = cos (ωt) Rps = cos ( ωt + Δs), the incident angle dependence of Rss can be measured by setting the vibration direction of the analyzer placed upstream of the detector to the same direction as the incident light, and the vibration direction of the analyzer is perpendicular to the incident light. , The dependency of Rps on the incident angle can be measured.

In the present invention, as shown in FIG. 11, linearly polarized light is condensed by a lens to become incident light.
The incident direction for providing the S-polarized component and the incident direction for providing the P-polarized component are orthogonal, and if the direction of the analyzer is adjusted to measure Rss, a change in the polarization state due to passing through the lens will not occur. Instead, the P-polarized component R of the reflected light generated by the incident light of the P-polarized component using the two-dimensional detector
pp can also be measured at the same time.

Similarly, it is possible to measure Rps and Rsp simultaneously. Rss, Rs measured in such an arrangement
The dielectric constants ε _e and ε _{o of} the anisotropic layer, the inclination angle θ of the main dielectric constant with respect to the sample surface, the film thickness d ₁ , etc., so that the incident angle dependence of p, Rps, and Rpp agree with the calculated value. Although the structure of the sample can be determined by optimizing the dielectric constant ε and the film thickness d ₂ of the phase, it is difficult to uniquely determine each parameter in consideration of the existence of a measurement error. Therefore, Rss, Rsp, Rps,
By measuring the dependence of Rpp on the incident azimuth, the reliability of the parameter determined by increasing the measured value for optimization is improved.

For the measurement of the incident azimuth dependence, a half-wave plate is inserted upstream of the lens used for focusing, and the optic axis is rotated so that the light of the S-polarized component incident on the sample and P
The incident direction of the polarized light component is changed. At this time, 1/2
The direction of the one-dimensional detector is also changed in synchronization with the rotation of the wave plate. However, as for Rsp and Rps, when the reflected light passes through the lens, the amplitude component of the polarized light changes due to the difference between the transmittances of the S component and the P component of the glass. Therefore, the phase differences Δs and Δp between the components Rss and Rsp and between the components Rpp and Rps are correctly measured. Thus obtained, the incident angle of the phase difference Δs or Δp, and the dielectric constants ε _e and ε _{o of} the anisotropic layer and the sample surface of the main dielectric constant coordinates so that the calculated values match the incident azimuth dependency. inclination angle theta, by optimizing the thickness d ₁ determining the structure of the sample to.

The incident direction of the S-polarized light and the P-polarized light to the sample can be realized by changing the direction of the half mirror.

[0039]

Next, an embodiment of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 is a diagram showing the configuration of an embodiment according to the present invention.

This embodiment is an apparatus provided with a stage 11, which is a light source 1 which is a 5 mW He-Ne laser, a polarizer 2, a half-wave plate 3, a method for condensing incident light and a method for parallelizing reflected light. 4, a half mirror 5, an analyzer 6, a CCD element 7 serving as a photodetector, a storage device 8 for temporarily storing measurement data, and numerically outputting a detection intensity of each element of the detector, an arithmetic unit 9 and a sample 10.

The measurement light emitted from the light source 1 is a polarizer 2,
The light enters the sample 10 on the stage 11 via the half mirror 5, the half-wave plate 3, and the lens 4. The reflected light from the sample 10 is transmitted through a lens 4, a half-wave plate 3, a half mirror 5,
The light enters the CCD device 7 via the analyzer 6.

Two one-dimensional CCD elements 7 were used, and the CCD elements were arranged so that their detection directions were orthogonal so that the P-polarized light component and the S-polarized light component could be detected by each CCD element.

As the lens 4, a 100 × objective lens of an Olympus microscope having a numerical aperture Na of 0.9 was used.
The size (diameter) of the observation area at the focal point is about 1 μm, and it is possible to measure an area at an incident angle of 0 ° to ± 66 °.

The measurement in this embodiment will be described.
First, a thin film formed on a substrate constituting the sample 10 by condensing parallel light of linearly polarized light generated by the light source 1 and passing through the polarizer 2 with the lens 4 so as to focus on the surface of the sample 10. Light incident on the The reflected light generated by this light is expanded again by passing through the lens 4 used to collect the incident light. Thereafter, after passing through the analyzer 6, C
The intensity of the S-polarized light component and the P-polarized light component of the reflected light is measured by the CD element 7. At this time, in particular, S
Attention is paid to the reflected light of the azimuth which is incident in the polarization state and the P polarization state.

In the measurement in this embodiment, the half mirror 5 is used because the light incident on the lens 4 and the reflected light from the sample 10 follow the same path. Incident light using the half mirror 5 to change the incident direction to the sample 10;
Alternatively, the traveling direction of the reflected light can be changed.

When measuring the polarization state of the reflected light, the analyzer 6 provided between the lens 4 and the CCD element 7 is rotated, and the polarization state is observed by observing the correlation between the rotation angle and the detected intensity. I do. Further, the rotation of the half mirror 5 and the half-wave plate 3 inserted between the half mirror 5 and the lens 4
Is rotated to rotate the polarization direction of the incident light and the direction detected by the CCD element 7, thereby measuring the reflected light intensity or the anisotropy of the polarization state of the reflected light.

The apparatus of this embodiment is based on a microscope manufactured by Olympus Corporation, and includes a polarizer 2, a half mirror 5, an analyzer 6, a CC
It is manufactured by adding a modification to add a D element 7, an arithmetic unit, and the like 8, 9. Stage 11 on which sample 10 is mounted
In order to make the center of rotation coincide with the focal point of the incident light and to make the axis of rotation parallel to the axis of symmetry of the incident light, a glass substrate on which aluminum having a diameter of about 2 μm was deposited was used.

The reflected light from the aluminum film placed on the stage 11 is measured by each element of the CCD element 7 as a detector, and the adjustment is completed in a state where the sum of these intensities does not change with respect to the rotation. The stage was fixed. In addition, each time the adjustment of each component is performed prior to the measurement of the sample 10,
Each time, the intensity of the reflected light from the aluminum deposition plate used here was measured to confirm the state of the apparatus.

A sample A prepared as described below was measured using the above apparatus. Sample A is a LB film of alkylamine acid PC2, which is a polyimide raw material for vertical alignment manufactured by Nippon Synthetic Rubber Co., Ltd., on a 1.1 mm-thick glass substrate (7059 manufactured by Corning Incorporated) in order to realize vertical alignment of liquid crystal. Langmuir-Blodgett film) was deposited. This LB
After the PC2 was spread on the water surface, the film was accumulated twice by moving the glass substrate up and down at 4 cm / s in a direction perpendicular to the water surface.
Thereafter, the resultant was heated in an oven at 200 ° C. for 3 hours to form a polyimide film.

The film thickness of the above polyimide film was adjusted to an incident angle of 70 using an ellipsometer MARY-102 manufactured by FIBRABO.
° and 50 ° were measured. 70 incident angle
In both cases of ° and 50 °, a significant difference between the measured polarization state of the reflected light (Δ, ψ) and the polarization state of the reflected light from the glass substrate surface was measured. Without
The thickness of the polyimide film could not be determined. This is presumably because the number of accumulations is small and the film thickness is small, and the refractive index of the polyimide film is close to that of the glass substrate.

On the above substrate, a cyanobiphenyl liquid crystal 5
CB (manufactured by Merck) was deposited. The vapor deposition at this time was performed by placing the container containing the substrate and the liquid crystal in a vacuum container and heating the liquid crystal container placed at the bottom of the vacuum container to evaporate the liquid crystal. The substrate was held near the ceiling in the container, and the evaporated surface (surface on which the polyimide film was formed) was directed downward, and the evaporated liquid crystal molecules were attached to form a liquid crystal layer. The distance between the liquid crystal container and the substrate was about 10 cm. At the time of sample preparation, the inside of the vacuum container was 1.2 × 10 ⁻² with a rotary pump.
After evacuation to mTorr, the inlet was closed. The temperature of the substrate was controlled by flowing hot water of 27 ° C. (300 K) through the substrate holder. The temperature of the liquid crystal container was increased from room temperature to about 70 ° C. by resistance heating, and this state was maintained for about 2 hours.

The incident azimuth and incident angle dependence of the phase difference of the reflected light from the sample were measured.
No dependence of the incident azimuth and the incident angle was observed for the P-polarized light incident component, and it became clear that the optical axis was perpendicular to the substrate.

The sample B was further measured using the apparatus of this example. Sample B was prepared on a 1.1 mm-thick glass substrate (7059 by Corning Incorporated) on a vertical alignment polyimide raw material PC2 and a horizontal alignment polyimide raw material PC1 by Nippon Synthetic Rubber Co., Ltd.
Was mixed at a ratio of 9: 1 to deposit an LB film.
After the mixed solution was spread on the water surface, the film was accumulated twice by moving the glass substrate up and down at 4 cm / s in a direction perpendicular to the water surface.
Thereafter, the resultant was heated in an oven at 200 ° C. for 3 hours to form a polyimide film.

When an attempt was made to measure the thickness of the above polyimide film using an ellipsometer MARY-102 manufactured by Five Bravo Co., the incidence angles were 70 ° and 50 ° similarly to Sample A.
In any case, the value indicating the polarization state of the reflected light (Δ, ψ) was not significantly different from the polarization state of the reflected light from the glass substrate surface, and the thickness of the polyimide film was determined. I couldn't do it. That is, it is concluded that this film has almost the same refractive index as the glass substrate and a small film thickness. Cyanobiphenyl-based liquid crystal 5CB (manufactured by Merck) was deposited on the substrate. Vapor deposition was performed by placing a container containing a substrate and liquid crystal in a vacuum container, and heating the liquid crystal container placed at the bottom of the vacuum container to evaporate the liquid crystal. The substrate was held near the ceiling in the container, and the liquid crystal layer was produced by attaching the evaporated liquid crystal molecules with the deposition surface (the surface on which polyimide was formed) facing downward. The distance between the liquid crystal container and the substrate was about 10 cm. In preparing the sample, the inside of the vacuum vessel was evacuated to 1.2 × 10 ⁻² mTorr by a rotary pump, and then the inlet was closed. The temperature of the substrate was controlled by flowing hot water of 27 ° C. (300 K) through the substrate holder. The liquid crystal container was heated from room temperature to about 70 ° C. by resistance heating and held for about 1 hour.

In performing the measurement according to the present example, the temperature of the room where the measurement was performed was set to 28 ° C. so that the deposited film became a liquid crystal phase (25 ° C. to 35 ° C.).

FIGS. 2 and 3 show the incident azimuth dependence of the polarization state of the reflected light from the sample measured when the incident angle was 70 ° and 50 °, and the S-polarized component was incident. FIGS. 4 and 5 show incident angles of 70 ° and 50 °, respectively, and depend on the incident direction of the polarization state of reflected light from the sample measured when a P-polarized component is incident. It is a figure which shows the property and the calculated value by the optimized parameter. The parameters describing the film structure were determined by the nonlinear least squares method so that the calculated values were closest to the measured values. In each figure, white circles indicate measured values, and solid lines indicate calculated values.

As a result, the anisotropic dielectric constant ε _e ε _o becomes 2.8.
It was found that the film was a uniaxial anisotropic film having a thickness of 5, 2.30, a thickness of 58 nm, and an inclination angle of 35 °. The orientation of the liquid crystal molecules in the plane of the sample was parallel to the moving direction of the substrate when the LB film was accumulated.

As described above, the optical axis of the film (axis of anisotropy)
When is not perpendicular to the substrate surface, the anisotropic dielectric constant of the film, the inclination angle of the optical axis, and the film thickness can be determined.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 6 is a diagram showing the configuration of the second embodiment of the present invention.

In this embodiment, a light source 24 using a 5 mW He-Ne laser, a polarizer 12, a lens 13 used for condensing incident light and collimating reflected light, a half mirror 14, an analyzer 15, and a one-dimensional light source are used. CCD device 16, which is a photodetector, storage device 17, which temporarily stores measurement data, and numerically outputs the detected intensity of each device of CCD device 16, arithmetic device 18, sample 1
9. Mirrors 20 to 2 for bending light emitted from light source 24
2. Mirrors 20-22, and
The polarizer 12 is configured to be rotatable about the same axis as the half mirror 14 as a rotation axis so that the incident direction of light can be changed while the position of the laser light source 24 is fixed.

The operation of the optical element and the folding operation in this embodiment are the same as those in the first embodiment.

As the CCD element 16, one-dimensional one is used.
In order to detect the P-polarized light component and the S-polarized light component in each CCD element, they are arranged so that their detection directions are orthogonal to each other. As the lens 13, a 100 × objective lens of an Olympus microscope having a numerical aperture Na of 0.9 was used. The size (diameter) of the observation area at the focal point is about 1 μm, and the incident angle is 0 °.
An area of ~ 66 ° can be measured.

A sample C prepared as described below was measured using the above-described apparatus. Glass substrate (Corning 7
059) is spin-coated with polyimide PI-C manufactured by Nissan Chemical Industries, and heated at 90 ° C. for 30 minutes, and then heated at 250 ° C. for 60 minutes.
Sample C was heated for a minute. In this state, an incident angle of 70 was obtained using an ellipsometer MARY-102 manufactured by Fibravo.
When the film thickness was measured in °, it was 72 nm. Then, using a cloth roller having a diameter of 50 mm, the indentation length is 0.05 mm, the rotation speed is 800 rpm, and the substrate movement speed is 3 mm.
Rubbing was performed twice at 0 mm / s.

FIGS. 7 and 8 show the incident angle dependence of the polarization state of the reflected light from the sample measured when the S-polarized component was incident, with the incident angles of 70 ° and 50 °, respectively. FIGS. 9 and 10 show incident angles of 70 ° and 50 °, respectively, and the incident state dependence of the polarization state of the reflected light from the sample measured when the P-polarized component was incident. It is a figure which shows the property and the calculated value by the optimized parameter. In each figure, white circles indicate measured values, and solid lines indicate calculated values. The parameters describing the film structure were determined by the nonlinear least squares method so that the calculated values were closest to the measured values.

As a result, the anisotropic dielectric constant ε _e ε _{o of the} alignment portion is obtained.
Were determined to be 3.17 and 2.58, the thickness was 33 nm, and the inclination angle of the main dielectric constant coordinate was 25 °.

Also in the above-described apparatus configuration, the anisotropic dielectric constant, the direction of the optical axis, and the thickness of the portion where the polyimide molecules are oriented and have optical anisotropy could be determined. The film thickness obtained by this measurement is 33 nm, but the film thickness measured before rubbing is 72 nm. It is considered that the difference between the two is due to the fact that the rubbing treatment does not orient the polyimide molecules over the entire film, but instead orients the surface at 33 nm. The phase difference obtained by the measurement in the present embodiment is the phase difference between the P-polarized component or the S-polarized component and the S-polarized component or the P-polarized component that appears in the reflected light when the S-polarized component or the P-polarized component enters. When there is no optical anisotropy, no phase difference occurs in the reflected light. That is, since the phase difference detected in the reflected light in the measurement according to the present embodiment is caused only by the portion having optical anisotropy, only the information of the portion having optical anisotropy can be extracted.

In the conventional method proposed in Japanese Patent Application No. 09-100330, an anisotropic layer is formed on a sample comprising an optically anisotropic layer such as a rubbed polyimide film and an isotropic layer. And the film thickness of both isotropic layers could be determined. However, since the film thickness is determined by the parameter optimization method by the least square method, the method according to the present invention having a small number of optimization parameters can obtain a more reliable value with the same measurement accuracy. . In each of the above-described embodiments, two one-dimensional CCD elements are used as photodetectors, and are arranged so that their detection directions are orthogonal so that each CCD element can detect a P-polarized component and an S-polarized component. It was explained that you do. This is an option for shortening the measurement time because a two-dimensional CCD element that also detects an unnecessary area requires a long detection time. Of course, a two-dimensional CCD element may be used, and in this case, the device configuration can be simplified.

[0070]

Since the present invention is configured as described above, it has the following effects.

Light in a linearly polarized state is incident on the sample using a lens, and the reflected light from the sample is converted into parallel rays using the same lens, and corresponds to the direction in which the incident light on the sample has only the S component or the P component. The incident angle and incident azimuth dependence of the phase difference of the reflected light can be measured with a spatial resolution of about 1 μm. From the measured values, the dielectric constant of the anisotropic film, the inclination angle of the main dielectric constant coordinate, and the anisotropic portion Became evaluable.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of a measuring apparatus according to the present invention.

FIG. 2 is a diagram illustrating the incident azimuth dependence of the phase difference of light corresponding to an incident angle of 50 ° among reflected light generated when an S-polarized component is incident on a sample B. Open circles indicate measured values, and lines indicate calculated values.

FIG. 3 is a diagram illustrating the incident azimuth dependence of the phase difference of light corresponding to an incident angle of 70 ° among reflected light generated when an S-polarized component is incident on a sample B. Open circles indicate measured values, and lines indicate calculated values.

FIG. 4 is a diagram illustrating the incident azimuth dependence of the phase difference of light corresponding to an incident angle of 50 ° among reflected light generated when a P-polarized component is incident on a sample B. Open circles indicate measured values, and lines indicate calculated values.

FIG. 5 is a diagram showing the incident azimuth dependence of the phase difference of light corresponding to an incident angle of 70 ° among reflected light generated when a P-polarized component is incident on a sample B. Open circles indicate measured values, and lines indicate calculated values.

FIG. 6 is a diagram showing the configuration of a second embodiment of the measuring device according to the present invention.

FIG. 7 is a diagram illustrating the incident azimuth dependence of the phase difference of light corresponding to an incident angle of 50 ° among reflected light generated when an S-polarized component is incident on a sample C. Open circles indicate measured values, and lines indicate calculated values.

FIG. 8 is a diagram illustrating the incident azimuth dependence of the phase difference of light corresponding to an incident angle of 70 ° among reflected light generated when an S-polarized component enters the sample C. Open circles indicate measured values, and lines indicate calculated values.

FIG. 9 is a diagram illustrating the incident azimuth dependence of the phase difference of light corresponding to an incident angle of 50 ° among reflected light generated when a P-polarized component enters the sample C. Open circles indicate measured values, and lines indicate calculated values.

FIG. 10 is a diagram illustrating the incident azimuth dependence of the phase difference of light corresponding to an incident angle of 70 ° among reflected light generated when a P-polarized component is incident on the sample C. Open circles indicate measured values, and lines indicate calculated values.

FIG. 11 is a diagram illustrating a relationship between a position of light entering a lens and an incident angle. Numerals 1 and 2 denote lenses, and the left side is a diagram showing the vibration direction of the electric field vector on a plane including the traveling direction of the incident light. It is the figure projected on the orthogonal surface.

[Explanation of symbols]

 1,24 light source 2,12 polarizer 3 1/2 wavelength plate 4,13 lens 5,14 half mirror 6,15 analyzer 7,16 CCD device 8,17 storage device 9,18 arithmetic unit 10,19 sample 11, 23 stage 21-23 mirror

Claims (10)

(57) [Claims] 1. A method in which parallel light of linearly polarized light is condensed by a lens so as to be focused on the surface of a sample to be incident light on a thin film formed on a substrate, and the generated reflected light passes through the lens. After the light is expanded again and passed through the polarizer, the intensity of each of the S-polarized light component and the P-polarized light component is measured by changing the incident direction to the sample, and the reflection depending on the incident angle of the light incident on the thin film is performed. By measuring the anisotropy of the light intensity or the polarization state of the reflected light, of the molecular orientation portion of the thin film,
A method for evaluating an anisotropic thin film, comprising determining a dielectric constant, a direction and a thickness of a main dielectric constant coordinate, and a dielectric constant and a thickness of a non-oriented portion. 2. The method for evaluating an anisotropic thin film according to claim 1, wherein the incident light is bent by a half mirror and is incident on the thin film. A method for evaluating an anisotropic thin film, comprising measuring each intensity of a polarized light component. 3. The anisotropic thin film evaluation method according to claim 2, wherein the anisotropy of reflected light intensity is measured by rotating a half mirror. 4. The method for evaluating an anisotropic thin film according to claim 2, wherein a half-wave plate is inserted between the half mirror and the lens, and the half-wave plate is rotated to change the polarization state of the reflected light. A method for evaluating an anisotropic thin film, comprising measuring anisotropy of a thin film. 5. The method for evaluating an anisotropic thin film according to claim 1, wherein an analyzer is provided between the lens and a detector for measuring the intensities of the S-polarized light component and the P-polarized light component. A method for evaluating an anisotropic thin film, comprising: inserting an analyzer, rotating the analyzer, and observing a correlation between a rotation angle and a detection intensity to measure a polarization state of reflected light. 6. A light source that generates measurement light that is parallel light of linearly polarized light, a stage on which a sample to be measured is mounted, a half mirror that folds the measurement light toward the sample on the stage, and the half mirror. A lens and a half-wave plate provided between the sample and the half mirror; a photodetector measuring an intensity distribution of reflected light reflected by the sample and passing through the half mirror; An analyzer provided between the photodetector, and a molecular orientation part of the thin film according to the detection content of the photodetector, a dielectric constant, a direction of a main dielectric constant coordinate, and a thickness, and a non-orientation part. A calculating device for calculating the dielectric constant and thickness of the sample, wherein the lens focuses the measurement light on the surface of the sample, makes the reflected light parallel again, and makes the reflected light incident on the half mirror. Anisotropic thin film evaluation Location. 7. The anisotropic thin-film evaluation device according to claim 6, wherein the stage is configured to be rotatable around an optical axis of the measurement light incident on the sample, and the arithmetic unit rotates the stage. The anisotropy of the reflected light intensity is measured by the detection content of the photodetector at the time,
An anisotropic thin film evaluation apparatus characterized in that a dielectric constant, a direction and a coordinate of a main dielectric constant of a molecular orientation part of the thin film, and a dielectric constant and a thickness of a non-orientation part are determined according to the result. 8. The anisotropic thin-film evaluation device according to claim 6, wherein the half mirror is configured to be rotatable about an optical axis of the measurement light incident on the sample, and the arithmetic unit is configured to include a half mirror. The anisotropy of the reflected light intensity is measured based on the detection content of the photodetector when rotated, and according to the result, the molecular orientation of the thin film, the dielectric constant, the direction of the main dielectric constant coordinate, and the thickness. Anisotropic thin film evaluation apparatus for determining a dielectric constant and a thickness of a non-oriented portion. 9. The anisotropic thin film evaluation apparatus according to claim 6, wherein the half-wave plate is configured to be rotatable around an optical axis of the measurement light incident on the sample, and the arithmetic unit is The anisotropy of the reflected light intensity is measured based on the detection content of the photodetector when the half-wave plate is rotated, and the dielectric constant and the main dielectric constant of the molecular orientation portion of the thin film are determined according to the result. An anisotropic thin film evaluation apparatus characterized in that the orientation and thickness of the non-oriented portion and the dielectric constant and thickness of the non-oriented portion are obtained. 10. The anisotropic thin-film evaluation device according to claim 6, further comprising an analyzer inserted between a detector and a lens, wherein the arithmetic unit is an analyzer. An anisotropic thin film evaluation apparatus characterized in that a correlation between a rotation angle and a detected intensity is observed based on the detection content of the photodetector when the light is rotated, and the polarization state of reflected light is measured.