CN1847816A - Optical anisotropy parameter measurement method and measurement device - Google Patents

Abstract

This invention provides an approach and a device which can measure the direction and magnitude of the optical axis of an optical anisotropic membrane and thickness of the membrane with a high speed and a high precision, and furthermore capable of distribution measurement by 2-D light receiving elements. The P-polarized monochromatic light is made to irradiate from a plurality of incident directions with a specific angular intervals while centering the normal line (Z) provided on the measurement point (M), the S-polarized light in the reflected light is detected corresponding to the incident directions, among the incident directions showing minimal values in the intensity of the reflection light, the azimuth direction ([Phi]<SB>A</SB>) of the optical axis (OX) is determined based on the incident direction (v<SB>1</SB>) in which the minimal value (V<SB>1</SB>) held between the maximal values ([Lambda]<SB>1</SB>) and ([Lambda]<SB>2</SB>), and the polar angle direction ([theta]) is determined based on the incident direction in which the minimal value (V<SB>3</SB>) held between maximal ([Lambda]<SB>1</SB>) of maximum peak and its adjacent maximal ([Lambda]<SB>3</SB>) of medium peak is measured.

Description

Optical anisotropy parameter measurement method and measurement device

technical field

The invention relates to an optical anisotropy parameter measuring method and a measuring device capable of measuring the optical axis anisotropy of a film test piece, and is particularly suitable for inspection of liquid crystal alignment films and the like.

Background technique

In liquid crystal displays, the rear glass substrate on which transparent electrodes and alignment films are laminated on the surface and the front side glass substrate on which color filters, transparent electrodes, and alignment films are laminated on the surface face the alignment films through a spacer. It is a structure in which polarizing filters are stacked on both the front and back sides of the alignment film while liquid crystal is sealed in the gap.

Here, in order to make the liquid crystal display operate normally, it is necessary to arrange the liquid crystal molecules uniformly in the same direction, and the alignment film determines the directionality of the liquid crystal molecules.

The reason why this alignment film can align liquid crystal molecules is that it has uniaxial optical anisotropy. If the alignment film has uniform uniaxial optical anisotropy over the entire surface, the liquid crystal display is less prone to defects, and if there is a portion with non-uniform optical anisotropy, the direction of the liquid crystal molecules is disordered, so the liquid crystal display becomes defective product.

That is, the quality of the alignment film itself will affect the quality of the liquid crystal display. Defects in the alignment film make the directionality of the liquid crystal molecules disordered, resulting in defects in the liquid crystal display.

Therefore, if only an alignment film with stable quality is used by pre-checking whether there is a defect in the alignment film when assembling the liquid crystal display, the yield of the liquid crystal display can be improved and the production efficiency can be improved.

Therefore, it has been proposed to measure the azimuth direction of the optical axis, the polar angle direction, the film thickness, etc. as an anisotropy parameter for the alignment film, and to check whether there is a defect by evaluating the optical anisotropy of the alignment film. .

The most general method is to use the method of ellipsometer, which can be measured quite accurately, but the measurement time of each measurement point needs about 2 minutes. When evaluating the anisotropy of an alignment film, it is necessary to measure A total of 10,000 points of 100×100 will take about 2 weeks for calculation alone, so it is ultimately impossible to load and inspect all of them on the production line.

Another method is to use the normal line upward from the measuring point of the film specimen as the center, and from a plurality of incident directions set at predetermined angular intervals, make the P polarized light or the S polarized light at a predetermined incident angle relative to the above measuring point. Irradiate, measure the reflected light intensity of the polarized light component included in the polarized light component in the reflected light, and the polarized light component perpendicular to the polarization direction of the irradiated light, thereby detect the reflected light intensity change corresponding to the incident direction, and thus can The azimuthal direction, the polar direction and the film thickness were calculated as parameters of the optically anisotropic thin film.

Patent Document 1 Japanese Patent Laid-Open No. 2001-272308

However, according to this method, when obtaining the parameters of an optically anisotropic thin film, it is necessary to perform measurements in all directions, and thus there is a problem that it takes time.

Furthermore, since it is necessary to measure the absolute amount of reflected light intensity, the measurement accuracy is affected by external factors such as the linearity of the sensitivity of the light receiving element and the dynamic range, and the possibility of large errors is high, making it difficult to improve the measurement accuracy.

In addition, since it is necessary to simultaneously calculate not less than 6 parameters such as the axial direction and size of the principal permittivity, the thickness of the film, and the normalization constant based on the nonlinear least square method, there is not only the calculation of the parameters that converge to the local minimum The possibility of solution, and there is a problem that requires huge computing time.

Contents of the invention

Here, the technical subject of the present invention is to provide a method and an apparatus capable of measuring the direction and inclination of the optical axis of an optically anisotropic film at high speed and with high precision, as well as measuring distribution from a two-dimensional light receiving element.

In order to solve this problem, the present invention is a method for measuring optical anisotropy parameters, which measures the azimuth direction and polar angle direction of the optical axis as the anisotropy parameter of the thin film specimen, and is characterized in that the The upward normal line of the measuring point is taken as the center, from a plurality of incident directions set at predetermined angular intervals, the monochromatic light of P polarized light or S polarized light is irradiated at a predetermined incident angle with respect to the above measuring point, and corresponding to the incident direction, detection The reflected light intensity of the polarized light component included in the polarized light component of the reflected light, which is perpendicular to the polarization direction of the irradiated light, in the incident direction where the reflected light intensity shows a minimum value, based on the measured Determine the incident direction of the minimum value sandwiched between the two maximum values of the largest peak or the minimum value sandwiched between the two maximum values of the middle peak, and determine the azimuth direction of the optical axis in the measurement point, based on the measured The incident direction that is the minimum value sandwiched between the maximum value of the maximum peak of the reflected light intensity and the maximum value of the adjacent intermediate peak, or the incident direction that is measured as the maximum value of the maximum peak , to determine the polar angle direction of the optical axis in its measurement point.

According to the present invention, first, by taking the normal line upward from the measurement point on the film test piece as the center, from a plurality of incident directions set at predetermined angular intervals, a single unit of P-polarized light or S-polarized light is directed to the above-mentioned measurement point. The colored light is irradiated at a predetermined incident angle, and the reflected light intensity of the polarized light component included in the reflected light and perpendicular to the polarization direction of the irradiated light is measured to detect the reflected light intensity corresponding to the incident direction.

When the incident direction changes between 0-360°, the measured value of the reflected light intensity of the thin film specimen with optical anisotropy is adjacent to the two maximum values as the maximum peak, and at the same time it is adjacent to the two poles as the middle peak. Contiguous large values, a waveform with four minima between each maximum.

Here, the angle of the azimuth direction of the optical axis of the thin film specimen, that is, the orientation of the optical axis in the measurement plane is equal to the direction in which the minimum value sandwiched between the two maximum values as the maximum peak is measured, so The direction is determined as the azimuth direction, and the angle is placed at the measurement point where the azimuth direction Φ _A =0.

In addition, since this direction deviates by 180° from the direction in which the minimum value sandwiched between the two maximum values as the middle peak was measured, it can also be measured from the direction of the two maximum values sandwiched as the middle peak. Determine the direction of the minimum value of .

Thereafter, the angle in the polar direction of the optical axis of the film sample, that is, the inclination angle of the optical axis with respect to the plane of the substrate can be calculated by Equation (2) or Equation (3).

Here, in formulas (2) and (3), all variables other than the angle θ in the polar angle direction are known or are measured values. Therefore, when according to formula (2), by detecting such an angle, it is The angle of the minimum value sandwiched between the maximum value of the largest peak and the maximum value of the intermediate peak is measured, or when according to formula (3), the angle of the maximum value of the maximum peak is measured by detection Angles can be calculated.

Formula 1

sinΦ _A = 0 (1)

$\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}\frac{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="A20061008403100181.png,A20061008403100191.png"\; state="\{\{state\}\}">N</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

$\frac{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; D.</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&mu;</span>}\frac{\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="N"\; filenames="A20061008403100181.png,A20061008403100191.png"\; state="\{\{state\}\}">N</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Φ _A : The incident direction where the minimum value sandwiched between the two maximum values as the maximum peak was measured (= azimuth angle direction = 0)

Φ _B : The direction of incidence where the maximum value as the maximum peak and the minimum value sandwiched between the maximum value as the middle peak are measured

Φ _C : The direction of incidence where the maximum value was measured as the maximum peak

Φ _D : The direction of incidence where the maximum value was measured as the maximum peak

θ: Angle in the polar direction of the optical axis from the substrate plane (tilt angle)

μ: +/- (The reflection intensity of P-polarized light incident on S-polarized light is "+", and the reflection intensity of S-polarized light incident on P-polarized light is "-")

Φ ₀ : Incident angle to the film

Φ ₂ : Angle of light leaving the substrate

N ₂ : Refractive index of the substrate

ε ₀ : Ordinary photopermittivity of the film specimen

Further, by irradiating the monochromatic light of P polarized light or S polarized light at a predetermined incident angle with respect to any measurement area on the film sample, the polarized light component contained in the reflected light and the irradiated light are detected. Two-dimensional distribution of the reflected light intensity of the polarized light component perpendicular to the polarization direction of the light. By detecting the reflected light intensity corresponding to the incident direction for each measurement point existing in the measurement area, the individual azimuth angles for multiple measurement points can be calculated. direction and polar direction.

In addition, when a liquid crystal aligning film is used as a thin film sample, the optical axes are aligned by rubbing, and the reflected light intensity has a minimum extreme value when incident near the rubbing direction and near the direction perpendicular thereto.

In addition, the angle (direction) of the maximum value of the reflected light intensity, which is the largest peak or the middle peak, depends on the direction of the polar angle. In the case of manufacturing a liquid crystal alignment film, the approximate polar angle is empirically controlled by the rubbing intensity (pressure) direction, based on the polar angle direction can be determined by formula (3).

Therefore, by centering on the rubbing direction and the direction perpendicular to it, the light is incident within a predetermined angle range, or the angle expected when the rubbing direction and the reflected light intensity have a maximum value as the maximum peak (direction ) as the center, so that the light is incident within a predetermined angle range, and the measurement range can be narrowed.

However, this angle range is based on the statistical deviation of the azimuth direction measured empirically in the production line of the liquid crystal alignment film. If the deviation is small, it is sufficient to limit it to about ±20°. If the deviation is large, it can be extended to ± within the range of about 45°.

Therefore, as long as the incident direction of the minimum value and maximum value of the reflected light is used, the azimuth direction and polar angle direction of the optical axis can be determined, and for the measurement point where these values are known, the direction of the film specimen can be measured. When the film thickness t, ordinary optical permittivity ε ₀ , and extraordinary optical permittivity ε _e of the anisotropic layer are measured, it is sufficient to use an ellipsometer or a reflector measuring instrument from two or three directions, and an extremely short time and accurately determine these optical anisotropy parameters.

Description of drawings

Fig. 1 is an explanatory diagram showing an example of an optical anisotropy parameter measuring device of the present invention.

FIG. 2 is a schematic diagram showing the relationship between the azimuth direction of the optical axis and the polar angle direction.

Fig. 3 is a graph showing the measurement results thereof.

Fig. 4 is an explanatory view showing another optical anisotropy parameter measuring device.

Fig. 5 is an explanatory view showing the transition of the position of each measurement point according to the rotation of the thin film sample.

Fig. 6 is an explanatory diagram showing polar angle distribution.

Fig. 7 is an explanatory diagram further showing another optical anisotropy parameter measuring device.

Fig. 8 is a graph showing the measurement results.

Fig. 9 is a graph showing the measurement results.

Detailed ways

In order to achieve the purpose of measuring the direction and inclination angle of the optical axis of an optically anisotropic film at high speed and with high precision, the present invention takes the normal line upward from the measuring point on the film sample as the center, and measures the direction and inclination angle from multiple points set at predetermined angular intervals. For each incident direction, the monochromatic light of P polarized light or S polarized light is irradiated at a predetermined incident angle with respect to the above-mentioned measurement point, and the difference between the polarized light component contained in the reflected light and the irradiated light is detected corresponding to the incident direction. The reflected light intensity of the polarized light components whose polarization directions are perpendicular to each other is based on the measured minimum value sandwiched between two maximum values as the maximum peak in the incident direction in which the reflected light intensity shows a minimum value. The direction of incidence is to determine the azimuth direction of the optical axis at the measurement point, based on the incident direction of the minimum value sandwiched between the maximum value of the maximum peak of the reflected light intensity and the minimum value of the adjacent maximum value of the intermediate peak. Direction, which determines the polar angle direction of the optical axis at its measurement point.

Fig. 1 is an explanatory diagram showing an example of an optical anisotropy parameter measuring device of the present invention, and Fig. 2 is a graph showing the incident direction in which the intensity of reflected light shows a minimum value, and the relationship between the azimuth direction of the optical axis and the direction of the polar angle Schematic diagram, Fig. 3 is a graph showing the measurement results of reflected light intensity, Fig. 4 is an explanatory diagram showing other optical anisotropy parameter measurement devices, and Fig. 5 is a graph showing the transition of each measurement point position along with the rotation of the film sample Explanatory diagrams, FIG. 6 is an explanatory diagram showing the measurement results of the inclination angle distribution, FIG. 7 is an explanatory diagram further showing other optical anisotropy parameter measurement devices, and FIGS. 8 and 9 are graphs showing the measurement results.

Example 1

The optical anisotropy parameter measuring device 1 shown in Fig. 1 and Fig. 2 is for measuring the azimuth direction Φ _A and A measuring device for the polar angle direction θ, which has a normal line Z upward from the measuring point M on the thin film test piece 3 as the center, from a plurality of incident directions set at predetermined angular intervals, and relative to the above-mentioned measuring point M. A light-emitting optical system 4 for irradiating polarized light or monochromatic light of S-polarized light at a predetermined incident angle; corresponding to the incident direction, detects the polarized light component included in its reflected light, which is orthogonal to the polarization direction of the irradiated light A light-receiving optical system 5 for the reflected light intensity of the polarized light component; and an arithmetic processing unit 6 for determining the polar angle direction of the optical axis at the measurement point M based on the measurement result.

The stage 2 has an elevating table 12 on the base 11 for moving the stage 2 up and down, a turntable 13 for rotating the stage 2, and an XY stage 14 for moving the stage 2 horizontally in the XY direction with respect to the rotation center Z of the turntable 13 , and the swing adjustment table 15 that adjusts the swing of the stage 2 when the turntable 13 rotates.

Further, above the stage 2, an autocollimator 7 for optically measuring the amount of wobble of the stage 2 is arranged, and based on the measurement result, the amount of wobble is adjusted.

The light-emitting optical system 4 is constructed in such a way that the He-Ne laser 21 with a wavelength of 632.8 nm and a light intensity of 25 mW faces the rotation center Z of the turntable 13 to configure an incident angle near the Brewster angle with better measurement accuracy (at In this example, it is 60°), and along its irradiation optical axis L _IR , polarizers 22, 22 are arranged, and the polarizers are composed of two Glan-Thomson prisms (extinction ratio 10 ^{− 6} ) Formation, thereby forming a structure in which only pure P-polarized light is irradiated.

The light-receiving optical system 5 is formed by disposing a pinhole slit for canceling light reflected from the back surface of the test piece 3 along the reflection optical axis L _RF irradiated from the above-mentioned laser 21 and reflected by the thin film test piece 3. 23; detection photons 24 and 24 formed by two Glan-Thomson prisms (extinction ratio 10 ⁻⁶ ) that transmit S-polarized light; wavelength selection filter 25 and photomultiplier tube 26, and photomultiplier tube 26 The detection signal is output to the arithmetic processing device 6 .

In addition, by using two detection photons 24 , only pure S-polarized light can be detected using the photomultiplier tube 26 .

In the arithmetic processing device 6, the detection signal output from the photomultiplier tube 26 is input every time the turntable 13 rotates by a predetermined angle, and the relationship between the rotation angle (incident direction) and the reflected light intensity is stored.

For a film sample 3 with optical anisotropy, when the incident direction is changed from 0 to 360°, the detected reflected light intensity changes generally as shown in the graph _G1 of FIG. 2 maxima ∧ ₁ , ∧ ₂ form a waveform of 2 maxima ∧ ₃ , ∧ ₄ of the middle peak, and four minima V ₁ -V ₄ between them.

In this way, as shown in Figure 2, from a plan view, the minimum values _V1 and _V2 are measured when incident from the longitudinal direction of the optical axis OX. , measure the minimum value V ₃ , V ₄ .

Therefore, in the incident directions v ₁ -v ₄ where the intensity of reflected light shows a minimum value, the minimum value V sandwiched between the two maximum values ∧ ₁ and ∧ ₂ forming the maximum peak is measured. The incident direction v ₁ of ₁ determines the azimuth direction Φ _A of the optical axis at the measuring point. That is, the incident direction v ₁ is set as the azimuth direction Φ _A =0.

In addition, based on the incident direction v3 of the minimum value V3 sandwiched between the maximum value ∧ ₁ forming the maximum peak of the reflected light intensity and the minimum value V ₃ forming the adjacent intermediate peak ∧ ₃ , the incident direction v ₃ is determined. The incident direction v 4 of the minimum value V 4 sandwiched by the maximum value ∧ ₂ forming _the maximum peak of the reflected light intensity and the minimum value V ₄ sandwiched by the adjacent maximum value ∧ ₄ forming the intermediate peak, or measured The incident direction λ _{1 or λ 2 forming the maximum peak maximum value Λ 1 or Λ 2 determines the} polar angle direction θ of the optical axis at the measurement point.

In this case, it is better to use the formula (2) to calculate

Φ _B ＝v ₃ -v ₁ ＝v ₄ -v ₁

In the case of calculation based on formula (3), it is better to use

|Φ _C |＝|Φ _D |＝|λ ₁ -λ ₂ |/2＝|λ ₃ -λ ₄ |/2

The above is an example of the configuration of the device of the present invention, and the method of the present invention will be described below.

Since then, since the azimuth direction Φ _A and the polar angle direction θ of the optical axis OX of the thin film specimen 3 are known, if the ellipsometer or reflector measuring instrument is used to measure from any two directions, the thin film specimen can be obtained The size and thickness of the main dielectric constant of the part.

The film sample 3 was prepared by spin-coating polyamic acid (PI-C manufactured by Nissan Chemical) on a glass substrate 8 with a spin coater, firing at 260° C., and rubbing with a polishing cloth.

The film thickness T of the thin film before rubbing was 80nm, and the dielectric constant ε=3.00.

After the rubbed test piece 3 is measured in advance by existing known methods, when the rubbing direction is 0°, the azimuth direction v ₁ of the optical axis OX=0.7°, the polar angle direction θ=24.2°, the ordinary light dielectric constant ε ₀ =2.83, the extraordinary optical permittivity ε _e =3.43, and the film thickness t of the anisotropic layer = 12 nm. The measurement time at this time is 60 seconds for one measurement point.

The film test piece 3 is loaded on the stage 2, the swing amount of the test piece is detected by the autocollimator 7, and the test piece 3 is adjusted to be horizontal by the swing adjustment table 15. Further, the height of the test piece 3 is adjusted to be optimized by the lifting table 12, so that the reflected light from the test piece 3 enters the light receiving element.

After the swing and height adjustment of the test piece 3 were completed, the turntable 13 was rotated to measure the reflected light intensity of the S-polarized light with respect to the incident direction.

The azimuth direction Φ _A of the rubbed thin film test piece 3 can be expected to be approximately parallel to the rubbing direction (X direction), and the polar angle direction θ can be expected to be at a position approximately orthogonal to it. Therefore, in this example, in The reflected light intensity was measured at intervals of 2° within a range of ±20° from the rubbing direction and a direction (Y direction) perpendicular to the rubbing direction to the center of ±20°.

The measurement range is preferably set within an arbitrary angle range such as ±45°, ±30°, etc., by surveying the deviation between the expected azimuth direction of the optical axis and the actual azimuth direction measured empirically.

The enlarged graphs G ₂ and G ₃ in FIG. 3 represent changes in reflected light intensity in respective measurement ranges centered on the X direction and the Y direction.

From the measurement data, the azimuth direction Φ _A and the polar angle direction θ of the optical axis OX can be obtained.

When calculating the inclination angle θ, the ordinary optical dielectric constant in the formula (2) is set to the dielectric constant ε ₀ =3.00 of the polyimide film before rubbing.

Fitting calculation is performed on the measurement results of graph G ₂ , and v ₁ =0.4° when calculating the orientation v ₁ where the received light intensity is extremely small. Therefore, it can be seen that the azimuth direction Φ _A of the optical axis OX is inclined by 0.4° from the Y axis.

In addition, when fitting calculations were carried out with respect to the measurement results of graph G ₃ , when calculating the orientation v ₃ where the received light intensity becomes extremely small, as Φ _B =v ₃ -v ₁ , the ordinary light permittivity ε ₀ =3.00( Dielectric constant of the polyimide film before rubbing), when the inclination angle θ is calculated based on the formula (2), θ=22.5°.

In this case, the measurement time for one measurement point is about 2 seconds.

Based on this result, in the two directions of the azimuth direction of the optical axis of the test piece and the direction perpendicular to it, when using an ellipsometer to measure, it can be known that the ordinary light permittivity ε ₀ = 2.79, and the extraordinary light permittivity ε _e = 3.44, and the film thickness t of the anisotropic layer = 11 nm. When the inclination angle θ is recalculated from the value of the ordinary optical permittivity ε ₀ , the value of θ is 24.5°.

In this case, even if the measurement time of the ellipsometer is added, the measurement time is about 4 seconds per measurement point, and the same result as the conventional method can be measured at high speed.

Example 2

FIG. 4 shows another embodiment of the optical anisotropy parameter measuring device, and the same parts as in FIG. 1 are denoted by the same reference numerals, so detailed description thereof will be omitted.

In the optical anisotropy parameter measuring device 31 of this example, the light-emitting optical system 4 is provided with a xenon lamp 32, and along its irradiation optical axis L _IR , a pinhole slit 34 is provided at the focal point of the reflecting mirror 33 so that A collimator lens 35 for parallelizing transmitted light, an interference filter 36, and a polarizer 22 for transmitting P-polarized light.

At this time, the interference filter 35 is set in such a way that its central wavelength is selected as 450nm, the full width at half maximum is selected as 2nm, the beam diameter irradiated on the film sample 3 is set as 10mm ² , and the incident angle is set as as 60° around Brewster's angle.

In addition, the light-receiving optical system 5 is provided with a detection photon 24 for transmitting S-polarized light, a wavelength selection filter 37 , and a two-dimensional CCD camera 38 along its reflection optical axis L _RF .

Thus, the intensity of reflected light from a plurality of measurement points Mij in the measurement area A of 10 mm ² irradiated on the test piece 3 can be measured simultaneously.

Sample 3 was prepared by spin-coating polyamic acid (PI-C manufactured by Nissan Chemical) on a Si substrate, firing at 260° C., and rubbing with a polishing cloth. When rubbing, rub from the left side to the right side of the test piece 3 with greater friction intensity.

When using the existing method to measure the inclination angle θ of the test piece 3 with 10×10=100 points, the distribution on the right side is 30-34°, and the distribution on the left side is 27-29°.

In addition, the measurement time is about 100 minutes for 100 points.

Set the test piece 3 on the stage 2, adjust the swing angle and height, rotate the turntable 13, and measure the binary distribution of the reflected light intensity with respect to the incident direction.

Fig. 5(a) shows measurement points Mij (i, j=1-10) in measurement area A before rotation.

Fig. 5(b) shows the rotation image as the turntable 13 rotates. If each measurement point Mij is represented by polar coordinates Mij=( _rn , α _m ), when the turntable 13 rotates at an angle γ, the position of Mij is represented by Mij =(r _n , α _m+γ ) represents.

Therefore, the reflected light intensity can be measured in the pixel area of the CCD camera 39 corresponding to Mij=( _rn , _αm +γ).

Thus, for each measuring point Mij of a total of 100 points, as in Example 1, ±20° centered on the rubbing direction (X direction) and ±20° centered on the direction perpendicular thereto (Y direction) In the range of 2°, the reflected light intensity was measured at intervals of 2°, and the distribution of the inclination angle θ was obtained using the formula (7). At this time, the measurement time for 100 measurement points was 2 seconds.

Based on this result, for each measuring point Mij of the test piece, in two directions of the azimuth angle direction Φ _A of the optical axis OX and the direction perpendicular to it, the measurement is carried out using an ellipsometer, and the ordinary optical permittivity ε ₀ , Abnormal photopermittivity ε _e , film thickness t of the anisotropic layer.

FIG. 6 shows the distribution of the inclination angle θ recalculated from the measured value of the ordinary optical permittivity ε ₀ .

Thus, the right side is a distribution of 30-34°, and the left side is a distribution of 27-29°, and the same results as those measured by the conventional method are obtained.

In this case, even if the measurement time of the ellipsometer is added, the measurement time for 100 measurement points is about 6 seconds, and the same result as the conventional method can be measured at an extremely high speed.

Example 3

Fig. 7 shows another embodiment of the optical anisotropy parameter measuring device, the same parts as in Fig. 1 are denoted by the same symbols, and the detailed description thereof is omitted.

The optical anisotropy parameter measuring device 41 of this example measures the optical anisotropy parameter without rotating the sample 3 .

The light emitting optical system 4 sets a plurality of illumination optical axes L _IR at intervals of 5° in the range of ±20° centered on the rubbing direction (X direction) and ±20° centered on the Y direction perpendicular thereto , the optical axis is such that light is irradiated to the measurement point M at an incident angle (60° in this example) near the Brewster's angle.

A semiconductor laser 42 with a wavelength of 780 nm and a light intensity of 20 mW and a polarizer 22 for transmitting P-polarized light are installed at each irradiation optical axis _LIR .

The light-receiving optical system 5 is formed by disposing a pinhole slit for canceling light reflected from the back surface of the test piece 3 along each reflection optical axis L _RF irradiated from the laser 42 and reflected by the thin film test piece 3 . slit 23; detection photon 24 for transmitting S polarized light; wavelength selection filter 25 and photomultiplier tube 26, and the detection signal of each photomultiplier tube 26 is output to the arithmetic processing device 6.

Sample 3 was prepared by spin-coating polyamic acid (PI-C manufactured by Nissan Chemical) on a glass substrate (whiteboard glass) with a spin coater, firing at 260° C., and rubbing with a polishing cloth.

The film thickness T of the thin film before rubbing was 93nm, and the dielectric constant ε=2.98.

When the rubbed test piece 3 is measured in advance by existing known methods, when the rubbing direction is 0°, the azimuth direction v ₁ of the optical axis OX=1.5°, the polar angle direction θ=20.4°, the ordinary light dielectric constant ε ₀ =2.78, the extraordinary optical permittivity ε _e =3.32, and the film thickness t of the anisotropic layer = 12 nm. The measurement time at this time is 60 seconds for one measurement point.

After adjusting the swing angle and height of the film sample 3, the reflected light intensity of the light output from each laser 42 was measured.

Fig. 8 and Fig. 9 are the measured data in the angle range of ±20° centered on the X direction (180°) and the Y direction (90°) respectively.

Fitting calculation was performed with respect to the measurement results in FIG. 8 , and v ₁ =1.8° when calculating the orientation v ₁ where the received light intensity is extremely small. Therefore, it can be seen that the azimuth direction Φ _A of the optical axis OX is inclined by 1.8° from the Y axis.

In addition, when performing fitting calculations with respect to the measurement results in FIG. 9 , the orientation v ₃ where the received light intensity is extremely small is calculated as Φ _B =v ₃ -v ₁ , ordinary photopermittivity ε ₀ =2.98 (polyamide before rubbing) imine film dielectric constant), when calculating the inclination angle θ based on formula (2), θ=19.0°.

In this case, the measurement time for one measurement point is about 0.5 seconds.

Based on this result, after using the ellipsometer to measure the azimuth direction of the optical axis of the specimen and the direction perpendicular to it, the ordinary light permittivity ε ₀ =2.76, the extraordinary light permittivity ε _e = 3.38. The film thickness of the anisotropic layer is t=16nm. When the inclination angle θ is recalculated from the value of the ordinary optical permittivity ε ₀ , θ=20.5°.

In this case, even if the measurement time of the ellipsometer is added, the measurement time is about 2 seconds per measurement point, and the same result as the conventional method can be measured at high speed.

Industrial availability

The present invention is applicable to film products with optical anisotropy, and is especially suitable for quality inspection of liquid crystal alignment films and the like.

Claims (13)

1. A method for measuring optical anisotropy parameters, which measures the azimuth direction and polar angle direction of the optical axis as the anisotropy parameter of the film specimen, With the normal line upward from the measurement point on the film specimen as the center, from a plurality of incident directions set at predetermined angular intervals, the monochromatic light of P-polarized light or S-polarized light is irradiated at a predetermined incident angle with respect to the above-mentioned measurement point , Corresponding to the incident direction, the reflected light intensity of the polarized light component perpendicular to the polarization direction of the irradiated light included in the polarized light component of the reflected light is detected, Based on the fact that, in the incident direction where the reflected light intensity shows a minimum value, a minimum value sandwiched between two maximum values as a maximum peak or a pole sandwiched between two maximum values as an intermediate peak is measured. The direction of incidence for small values determines the azimuthal direction of the optical axis in the measuring point, Based on the incident direction where the minimum value sandwiched between the maximum value as the maximum peak of the reflected light intensity and the maximum value as the adjacent intermediate peak is measured, or based on the maximum value that is measured as the maximum peak The direction of incidence of the value determines the polar angle direction of the optical axis in the point of its measurement. 2. The method for measuring optical anisotropy parameters according to claim 1, wherein by rotating the test piece around the normal line, irradiating P polarized light or S Polarized monochromatic light. 3. The method for measuring an optical anisotropy parameter according to claim 1, wherein said P-polarized light or S-polarized light is irradiated with said normal line as a center from a plurality of light emitting parts arranged at predetermined angular intervals around it. Monochromatic light. 4. The optical anisotropy parameter measuring method according to any one of claims 1 to 3, wherein the anisotropy of the optical axis is measured for a plurality of measuring points by moving the thin film test piece. 5. The method for measuring optical anisotropy parameters as claimed in claim 1, wherein the incident direction of the monochromatic light of P polarized light or S polarized light incident at predetermined angle intervals with the normal line as the center is the first angle and the second angle as the center, respectively set a plurality of predetermined angle intervals within a predetermined angle range, wherein the first angle is expected when there is a minimum value sandwiched between two maximum values as the maximum peak, The second angle is expected when there is a minimum value sandwiched between the maximum peak maximum value and the intermediate peak maximum value, the maximum peak maximum value, or the intermediate peak maximum value. 6. A method for measuring optical anisotropy parameters, which measures the azimuth direction and polar angle direction of the optical axis as the anisotropy parameter of the film specimen, The monochromatic light of P-polarized light or S-polarized light is incident at a predetermined angle on the above-mentioned measurement area from a plurality of incident directions set at predetermined angular intervals with the normal line upward from the center of the measurement area on the film specimen as the center. angled exposure, By detecting the reflected light intensity distribution of the polarized light component included in the polarized light component of the reflected light and perpendicular to the polarization direction of the irradiated light, each measurement point existing in the measurement area is detected two-dimensionally corresponding to the incident direction. the respective reflected light intensities, For each measurement point, based on the fact that in the incident direction where the reflected light intensity shows a minimum value, a minimum value sandwiched between two maximum values as the maximum peak or two maximum values as an intermediate peak is measured. The incident direction of the minimum value sandwiched by the value determines the azimuth direction of the optical axis in the measurement point, Based on the incident direction where the minimum value sandwiched between the maximum value as the maximum peak of the reflected light intensity and the maximum value as the adjacent intermediate peak is measured, or based on the maximum value that is measured as the maximum peak The direction of incidence of the value determines the polar angle direction of the optical axis in the measurement point. 7. The method for measuring optical anisotropy parameters as claimed in claim 1, wherein based on the determined azimuth direction, at least two arbitrary directions are measured using an ellipsometer or a reflector measuring instrument to obtain the optical anisotropy as The principal dielectric constant and film thickness of anisotropic thin films with anisotropic parameters. 8. An optical anisotropy parameter measuring device, which measures the azimuth direction and polar angle direction of the optical axis as the anisotropy parameter of the thin film specimen, having: With the normal line upward from the measurement point on the film specimen as the center, from a plurality of incident directions set at predetermined angular intervals, the monochromatic light of P-polarized light or S-polarized light is irradiated at a predetermined incident angle with respect to the above-mentioned measurement point luminescent optical system; a light-receiving optical system that detects the intensity of reflected light of a polarized light component included in the reflected light that is perpendicular to the polarization direction of the irradiated light, corresponding to the incident direction; and An arithmetic processing device based on the measurement of a minimum value sandwiched between two maximum values as a maximum peak or two maximum values as an intermediate peak in an incident direction in which the reflected light intensity shows a minimum value. The incident direction of the minimum value sandwiched by the value, determine the azimuth direction of the optical axis in the measurement point, and at the same time, based on the maximum value that is the maximum peak of the reflected light intensity and the pole that is the intermediate peak adjacent to it. The polar angle direction of the optical axis at the measurement point is determined based on the incident direction of the minimum value sandwiched between the large values, or the incident direction of the maximum value measured as the maximum peak. 9. The optical anisotropy parameter measurement device according to claim 8, wherein said test piece is arranged to be rotatable about said normal line. 10. The optical anisotropy parameter measurement device according to claim 8, wherein said light-emitting optical system and light-receiving optical system are arranged in plural groups at predetermined angular intervals around said normal line. 11. The optical anisotropy parameter measurement device according to claim 8, comprising a stage for moving the thin film sample in order to measure the anisotropy of the optical axis at a plurality of measurement points. 12. The optical anisotropy parameter measuring device according to claim 8, wherein the incident direction of the monochromatic light of P polarized light or S polarized light incident at predetermined angle intervals with the normal line as the center is the first angle and the second angle as the center, respectively set a plurality of predetermined angle intervals within a predetermined angle range, wherein the first angle is expected when there is a minimum value sandwiched between two maximum values as the maximum peak, The second angle is when there is any one of the minimum value sandwiched between the maximum value as the largest peak and the maximum value as the intermediate peak, the maximum value as the maximum peak, or the maximum value as the intermediate peak expected. 13. A device for measuring optical anisotropy parameters, which measures the azimuth direction and polar angle direction of the optical axis as an anisotropy parameter of a thin film specimen, having: The monochromatic light of P-polarized light or S-polarized light is incident at a predetermined angle on the above-mentioned measurement area from a plurality of incident directions set at predetermined angular intervals with the normal line upward from the center of the measurement area on the film specimen as the center. Light-emitting optical system for angled illumination; A light-receiving optical system having a two-dimensional light-receiving element, which measures the reflected light intensity distribution of the polarized light component included in the reflected light and the polarized light component perpendicular to the polarization direction of the irradiated light. Each measurement point detects the respective reflected light intensity corresponding to the incident direction; and An arithmetic processing device for measuring a minimum value sandwiched between two maximum values as a maximum peak or an intermediate peak in an incident direction in which the reflected light intensity exhibits a minimum value for each measurement point. The incident direction of the minimum value sandwiched between the two maximum values of , determine the azimuth direction of the optical axis in the measurement point, and at the same time, based on the maximum value measured as the maximum peak of the reflected light intensity and the The polar angle direction of the optical axis at the measurement point is determined based on the incident direction of the minimum value sandwiched between the maximum value of the middle peak, or based on the incident direction in which the maximum value of the maximum peak was measured.

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