JPH11201732A - Measuring method and measuring device of gap between substrates with multi-layer films - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accurate measuring method and a measuring device of a gap between multi-layer films provided face to face on both substrates. SOLUTION: When the gap between opposite faces of multi-layer films of both electrode substrates 10, 20 has a large or small gap value, a white light source 60 projects light to both electrode substrates 10, 20. A spectral device 90 measures the interference intensity of the reflected light on each film boundary face of both multi-layer films via the projected light at a large gap value as first spectrometric data in response to the inverse number of the wavelength, and it measures the interference intensity of the reflected light on each film boundary face of both multi-layer films via the projected light at a small gap value as second spectrometrie data in response to the inverse number of the wavelength. An LPF 100 extracts the component other than the interference component of the reflected light on the opposite faces of both multi-layer films in the first spectrometric data, a subtracting device 110 subtracts the extracted component from the second spectrometric data, and a frequency analyzer 120 frequency-analyzes the subtracted data and measures the small gap value as the gap between the opposite faces of both multi-layer films.

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 measuring a gap between two substrates having a multilayer film, such as two electrode substrates of a liquid crystal cell.

[0002]

2. Description of the Related Art Conventionally, for example, in measuring a gap between two glass plates, a wavelength response of light interference caused by an optical path difference between respective reflected lights by the two glass plates is measured as data, and the gap is measured. There is a way to measure

[0003]

Since the gap is measured based on only the two glass plates, the wavelength response data has information on only the gap. Therefore, the analysis of the wavelength response data is easy and the measurement accuracy is good. Specifically, if the gap between the two glass substrates is d, and the wavelength and intensity of the interference light are λ and I,
The variation ΔD of the wavelength response is expressed by the following equation (1).

[0004]

ΔD = Icos (4dπ / λ) Here, since d corresponds only to the gap between the two glass substrates, the peak, frequency and phase of the measured wavelength response data are analyzed to obtain The gap d can be determined with accuracy based on the equation.

However, for example, both electrode substrates of a liquid crystal cell are formed by adding a multilayer film to the inner surface of each glass plate so as to face each other. In this case, the interference phenomenon due to the optical path difference of each reflected light at all the film interfaces of each multilayer film is added to the interference phenomenon due to each reflected light of both glass substrates due to the gap between the opposed film interfaces. Therefore, d in the equation (1)
Is complicated, including the gap between the interfaces of the facing films.
The resulting wavelength response data is complicated as shown in FIG. Therefore, it is difficult to extract and analyze only the gap between the two electrode substrates, that is, the gap between the two multilayer films based on such data, which causes a significant decrease in measurement accuracy.

In view of the above, an object of the present invention is to provide a method and an apparatus for accurately measuring a gap between multilayer films provided on both substrates so as to face each other. And

[0007]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, both substrates are opposed to each other by their respective multilayer films (12 to 14, 21 to 25). When the gap between the opposing surfaces of the respective multilayer films of the two substrates (11, 21) is the first gap value, light is projected from one side to the other of the two substrates, and the light is projected onto the respective films of the both multilayer films. Forming the first spectral measurement data by performing spectral measurement of the interference intensity of light reflected by the interface according to the reciprocal of the wavelength;
When an interference component other than the interference component of the light reflected by the opposing surfaces of both multilayer films in the first spectral measurement data is extracted, and the gap between the opposing surfaces is a second gap value different from the first gap value Light is projected from one of the two substrates to the other, and the interference intensity of the light reflected by the interface between the films of the two multilayer films is spectrally measured according to the reciprocal of the wavelength to form second spectral measurement data. A multilayer in which the extracted interference component is subtracted from the second spectral measurement data to form subtraction data, and the subtraction data is subjected to frequency analysis to measure a second gap value as a gap between opposing surfaces of both multilayer films. A method for measuring a gap between substrates with a film is provided.

According to the present invention, the subtraction data contains information on the gap between the opposing surfaces of the two multilayer films, that is, the interference component of the reflected light at the interface between the two multilayer films based on the opposing surfaces of the two multilayer films. Only the interference component of the reflected light will be included.
As a result, even if both substrates have multilayer films, the second gap value, that is, a desired gap between both substrates can be measured with high accuracy without being affected by these multilayer films.

The magnitude of the first and second gap values is not particularly limited, and it is sufficient that the second gap value is a desired gap between both substrates. According to the second aspect of the present invention, both the substrates and the respective multilayer films (12 to 1) are provided.
4, 21 to 25) when the gap between the opposing surfaces of the multilayer films of the two substrates (11, 21) is the first and second gap values, from one to the other of the two substrates. Light emitting means (60, 70, 8)
0) and the first gap value, the interference intensity of the light reflected by the interface between the respective films of the two multilayer films is spectroscopically measured according to the reciprocal of the wavelength to form first spectral measurement data, Also, spectrometry data for forming second spectrometry data by spectroscopically measuring the interference intensity of light reflected by the interface of each of the two multilayer films by light projection at the second gap value according to the reciprocal of the wavelength. Forming means (90), extracting means (100, 120) for extracting an interference component other than the interference component of the light reflected by the opposing surfaces of the two multilayer films in the first spectral measurement data, and extracting means from the second spectral measurement data Subtracting means (110) for subtracting the extracted interference component to form subtraction data, and frequency-analyzing the subtraction data to measure a second gap value as a gap between the opposing surfaces of both multilayer films according to the analysis result. Frequency analysis means (12 ) And the measuring device between the multilayer film substrate gap provided is provided.

[0010] This makes it possible to provide a measuring device that can achieve the functions and effects of the first aspect of the present invention.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example in which the measuring device according to the present invention is applied to the measurement of the cell gap of the liquid crystal cell S. The measuring device includes a heating and pressing device 50, and the heating and pressing device 50 accommodates the liquid crystal cell S.

Here, as shown in FIGS. 1 and 2, the liquid crystal cell S includes both electrode substrates 10 and 20 having a multilayer film.
And many spacers 40 are interposed. In addition, no liquid crystal is injected between the two electrode substrates 10 and 20, and the liquid crystal cell S is in an empty cell state.

The electrode substrate 10 is formed by sequentially laminating a plurality of stripe-shaped transparent conductive films 12, insulating films 13, and alignment films 14 on the inner surface of a glass substrate 11. On the other hand, the electrode substrate 20 includes a color filter 22, a plurality of stripe-shaped transparent conductive films 23, and an insulating film 2 on an inner surface of a glass substrate 21.
4 and the alignment film 25 are sequentially laminated.

The liquid crystal cell S is accommodated in the heating and pressing device 50 with the electrode substrate 20 below the electrode substrate 10. The measuring device includes a white light source 60, a half mirror 70, and an objective lens 80. White light source 60
Is reflected by the half mirror 70 and enters the objective lens 80.

The objective lens 80 condenses the light from the half mirror 70 and makes it incident on the liquid crystal cell S through the upper surface 51 of the heating and pressing device 50. Further, the objective lens 80 condenses the reflected light from the liquid crystal cell S, passes through the half mirror 70, and enters the light receiving surface of the spectroscopic device 90 as interference light (described later). The spectroscopic device 90 disperses the interference light to the light receiving surface, measures the wavelength response of the intensity of the interference light, and outputs the result to the low-pass filter 100 (hereinafter, referred to as LPF 100) and the subtraction device 110 as wavelength response measurement data. .

The LPF 100 removes high frequency components from the frequency components of the wavelength response measurement data according to the reciprocal (1 / wavelength) of the wavelength of light, and stores the remaining frequency components in the memory 120 as filter signals. This means that the memory 120 stores the intensity of the wavelength response measurement data other than the intensity corresponding to the high frequency component.

The memory 120 outputs the stored data to the subtraction device 110. The subtraction device 110 includes the spectroscopic device 90
Is subtracted from the output data of the memory 120 and output to the frequency analyzer 120 as subtracted data. The frequency analyzer 120 analyzes the frequency of the subtraction data and outputs the result to the heating / pressing device 50 as analysis data. Next, a method of measuring the cell gap of the liquid crystal cell S (the cell gap between the alignment films of the two electrode substrates 10 and 20) using the above-described measuring device will be described with reference to FIGS.

First, in step S1 of FIG. 3, the gap between the two electrode substrates 10 and 20 of the liquid crystal cell S is temporarily set by the heating and pressing device 50. At this time, both electrode substrates 1
The gap between 0 and 20 (hereinafter referred to as a temporary setting gap) is set to be larger than the cell gap of the liquid crystal cell S (the gap between the two electrode substrates 10 and 20 finally required) (FIG. 4). (A)).

The provisionally set gap is set to be sufficiently larger than the thickness of each film of the electrode substrates 10 and 20 and the detection sensitivity to the reflected light from the inner surface of the glass substrate 21 of the electrode substrate 20 is set. Objective lens 8
The depth of focus is set smaller than 0. Thereafter, in step S2, the white light of the white light source 60 is
0 and the liquid crystal cell S through the objective lens 80.

At this time, the white light incident on the liquid crystal cell S is reflected at the interface between the films of the electrode substrates 10 and 20.
Then, the respective reflected lights interfere with each other based on the optical path difference therebetween, and enter the objective lens 80 as interference light. Then, the objective lens 80 condenses the incident interference light, passes through the half mirror 70, and enters the light receiving surface of the spectroscopic device 90.
Along with this, the spectroscopic device 90 separates the incident interference light, measures the wavelength response of the incident interference light, and outputs it to the LPF 100 as first spectral measurement data (see FIG. 5A).

FIG. 5 shows the first spectroscopic measurement data.
When the horizontal axis in (a) is (1 / wavelength), the gap d is large, so that each of the alignment films 1 on both electrode substrates 10 and 20 can be obtained.
The intensity change due to the interference component of the reflected light at each film interface other than 4 and 25 is included as a high-frequency component in (4dπ / λ) in the equation (1). Therefore, in the LPF 100,
A cutoff frequency is set in advance between the interference component of the reflected light at each film interface and the interference component of the reflected light at both alignment films.

Then, in step S3, the first spectral measurement data is passed through the LPF 100. As a result, LPF1
At the output of 00, an interference component generated due to the relationship between the light reflected by each film other than the both alignment films is extracted (see FIG. 5B). Therefore, the extracted output of the LPF 100 is stored in the memory 120 in step S4.

Next, in step S5, the heating and pressurizing device 50 heats and presses the two electrode substrates 10 and 20 with the gap between the two electrode substrates 10 and 20 toward the original cell gap (FIG. b)). At this time, the gap between the two electrode substrates 10 and 20 has a value near the cell gap. In step S6, the light from the white light source 60 passes through the half mirror 70 and the objective lens 80 to enter the liquid crystal cell S in the same manner as described above, and the interference reflected light from the liquid crystal cell S is transmitted through the objective lens 80 and the half mirror 70. The light enters the light-receiving surface of the through-spectrometer 90.

Accordingly, the spectroscopic device 90 performs step S
At 6, the wavelength response is measured again at the same position as the measurement position of the first spectral measurement data stored in the memory 120 in step S4, and the second spectral measurement data (FIG. 5C)
(See Reference) to the subtraction device 110. Here, in the second spectral measurement data, distortion occurs because the interference component related to the cell gap and the interference component related to the other film overlap at a close frequency.

Even if the second spectral measurement data is subjected to frequency analysis, no clear peak corresponding to the gap appears due to the distortion (see FIG. 5D). Next, in step S7, the first spectral measurement data stored in the memory 120 is subtracted from the second spectral measurement data by the subtraction device 110. Thereby, interference components other than the interference component caused by the gap between the two electrode substrates 10 and 20 can be removed from the second spectral measurement data.

In other words, the waveform component of the subtraction output of the subtraction device 110 is mainly composed of the interference component caused by the gap between the two electrode substrates 10 and 20 (FIG. 5E).
reference). This means that the subtraction output of the subtraction device 110 is improved to have a waveform close to cos (4dπ / λ) in the equation (1).

In step S8, as a result of frequency analysis of the subtraction output of the subtraction device 110 by the frequency analyzer 120, an extra peak is removed, and the two electrode substrates 1 are removed.
The peak of the interference component due to the cell gap between 0 and 20 appears (see FIG. 5 (f)). Then, based on the frequency analysis result, the frequency analyzer 120 calculates a peak wavelength,
The frequency and the phase are detected and converted into a gap between the two electrode substrates 10 and 20 (a gap between the two alignment films 14 and 25) to adjust the degree of pressurization by the heating and pressurizing device 50. The feedback to the pressure device 50 is provided.

Thus, the gap between the two electrode substrates 10 and 20 is accurately controlled toward the cell gap. As a result, the gap between the two electrode substrates 10 and 20 can be controlled with high accuracy in real time. As described above, according to the present embodiment, based on the first and second spectral measurement data, the interference components of each reflected light other than the reflected light by both alignment films in the multilayer structure of both electrode substrates 10 and 20. Is properly removed. Therefore, the cell gap between the two electrode substrates 10 and 20 can be accurately measured.

In the embodiment of the present invention, when the gap between the two electrode substrates 10 and 20 described in the above embodiment changes in a tapered shape, the conventional method and the above-described method can be used by the equation (1). The gap was measured by the method described in the embodiment (see FIG. 6). As a result, the measurement data by the method described in the above embodiment (see FIG. 6A) is more accurate in measuring the gap than the measurement data by the conventional method (see FIG. 6B). It was found to be significantly improved.

Further, in the above embodiment, the first and second spectroscopic measurement data are obtained at the same position of the liquid crystal cell. However, if the thicknesses of the multilayer films of the liquid crystal cell are stable. The measurement position of the spectral measurement data may be only one representative point in the liquid crystal cell. Here, if the thickness of each multilayer film is stable in the production lot of the liquid crystal cell, the measurement of the spectroscopic measurement data may be performed for each lot.

In practicing the present invention, the white light source 60 described in the above embodiment may be a wavelength sweep light source, and the spectrometer 90 may be a light intensity detector. Further, in the practice of the present invention, not only when measuring the cell gap of a liquid crystal cell having a multilayer film, but also in a state where substrates such as both glass substrates each having a multilayer film are arranged to face each other via each multilayer film. Therefore, even when the present invention is applied to the case where the gap between the opposing surfaces of both multilayer films is measured, substantially the same operation and effect as the above embodiment can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a liquid crystal cell gap measuring apparatus according to the present invention.

FIG. 2 is a schematic sectional view of the liquid crystal cell of FIG.

FIG. 3 is a process chart showing a method for measuring a gap of a liquid crystal cell by the gap measuring device.

4A is a schematic partial cross-sectional view showing a temporarily set gap state of a gap of a liquid crystal cell, and FIG. 4B is a schematic partial view showing a state where the gap of the liquid crystal cell is set to a value near the cell gap; It is sectional drawing.

FIGS. 5A to 5C are graphs each showing a relationship between the reflection intensity of the interference light and the reciprocal of the wavelength, and FIGS.
Is a graph showing the relationship between the power of the interference light and the frequency of the light, (e) is a graph showing the relationship between the reflection intensity of the interference light and the reciprocal of the wavelength, and (f) is the graph showing the relationship between the power of the interference light and the light. It is a graph which shows the relationship with a frequency.

FIG. 6A is a graph showing a relationship between a gap and a measurement position according to a modification of the embodiment, and FIG.
Is a graph showing the relationship between the modified example and the measurement position of the same gap when measured by a conventional measurement method.

FIG. 7 is a graph showing the relationship between the light reflectance of a conventional multilayer film and the reciprocal of the wavelength.

[Explanation of symbols]

S: liquid crystal cell, 10, 20: electrode substrate, 11, 21: glass substrate, 12, 23: transparent conductive film, 13, 24: insulating film, 14, 25: alignment film, 50: heating and pressing device, 60:
White light source 70: half mirror, 80: objective lens, 90
... Spectroscope, 100 ... LPF, 120 ... Memory, 110
... subtraction device, 120 ... frequency analyzer.

Claims (2)

[Claims] 1. A substrate between two substrates (11, 21) which are arranged so as to be opposed to each other in each of the multilayer films (12 to 14, 21 to 25). When the gap is the first gap value, light is projected from one side of the two substrates to the other, and the interference intensity of the light reflected by the interface between the respective films of the two multilayer films by the projected light is spectrally measured according to the reciprocal of the wavelength. The first spectral measurement data is formed, and an interference component other than the interference component of the light reflected by the facing surfaces of the two multilayer films is extracted from the first spectral measurement data. When the second gap value is different from the gap value, the light is projected from one of the two substrates to the other, and by this light, the interference intensity of the light reflected by the interface between the films of the multilayer films is reciprocal of the wavelength. Spectroscopic measurement and form second spectroscopic measurement data The extracted interference component is subtracted from the second spectral measurement data to form subtraction data. The subtraction data is subjected to frequency analysis to measure the second gap value as a gap between the facing surfaces of the two multilayer films. The method for measuring the gap between substrates with a multilayer film as described above. 2. The two substrates (12, 14, 21 to 25), which are arranged so as to face each other, between the opposing surfaces of the respective multilayer films of the two substrates (11, 21). When the gap has the first and second gap values, light projecting means (60, 60) for projecting light from one of the substrates to the other thereof.
70, 80), and first spectral measurement data obtained by spectrally measuring the interference intensity of light reflected by the interface between the two multilayer films by the light projection at the first gap value according to the reciprocal of the wavelength. And the second spectroscopic measurement data obtained by spectrally measuring the interference intensity of light reflected by the interface between the two multilayer films by the light projection at the second gap value according to the reciprocal of the wavelength. A spectrometry data forming means (90) for forming an image; an extraction means (100, 120) for extracting an interference component other than an interference component of light reflected by the opposing surfaces of the multilayer films in the first spectrometry data; Subtraction means (11) for subtracting the interference component extracted by the extraction means from the second spectral measurement data to form subtraction data
0), and a frequency analysis means (120) for frequency-analyzing the subtraction data and measuring the second gap value as a gap between the opposing surfaces of the multilayer films according to the analysis result. Measuring device for gap.