JPH08189812A - Optical film structure measuring apparatus and film thickness measuring apparatus and method - Google Patents

Abstract

(57) Abstract: An optical film structure measuring apparatus capable of easily measuring the structural period of a reversible thermosensitive recording material in a reversible thermosensitive recording medium using a mirror-like support that does not transmit laser light. To provide. An apparatus for optically measuring a film structure of a sample 1 having a light-transmitting property, the sample table 2 having a mirror-reflecting surface as a table surface on which the sample 1 is mounted, and the sample. A laser light source 3 which is a light source for irradiating a sample and is spaced apart from the table 2, and a photodetector 4 which is arranged on the same side as the laser light source 3 facing the sample table 2. Membrane structure measuring device. It is preferable that the photodetector 4 is configured by fixedly disposing a plurality of sensors for measuring the scattering intensity of laser light at different detection angles of scattered light.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an apparatus for optically measuring a film structure of a sample having light transmittance. The present invention also relates to an apparatus and method for optically measuring the film thickness of a sample having optical transparency.

[0002]

2. Description of the Related Art A reversible thermosensitive recording medium is generally formed by coating a solution containing an organic low molecular weight substance and a resin matrix on a support,
It is produced by drying and forming a heat-sensitive layer made of a reversible heat-sensitive recording material. When measuring the structural period of such a reversible thermosensitive recording material, an optical film structure measuring device utilizing light scattering is used. A conventional optical film structure measuring device basically comprises a laser light source that irradiates a sample with laser light, and a light receiving unit that receives the intensity of the laser light when the irradiated laser light passes through the sample and is scattered. It is configured.

FIG. 2 schematically shows the structure of a conventional optical film structure measuring apparatus. This apparatus oscillates a laser beam 12 from a laser oscillator 11 which is a laser light source, and a mirror 13
The laser light 12 is passed through the hole 15 of the sample stand 14 and applied to the sample 16 on the sample stand 14, at which time the intensity of the laser light scattered on the surface of the sample is detected by the photodiode 1 which is a photodetector.
The structural period can be obtained by measuring at 7. Further, the photodiode 17 measures the scattered laser light intensity while moving in the range of the angle θ.

By the way, as a reversible thermosensitive recording medium,
In addition to those having a reversible thermosensitive recording layer provided on a transparent support, those having a reversible thermosensitive recording layer provided on a mirror-like support that does not transmit laser light are also used. And also in the latter type of medium, it is required to measure the structural period.

However, in the above-mentioned conventional optical film structure measuring apparatus, since the sample is irradiated with the laser beam and the scattering intensity of the laser beam transmitted through the sample is measured,
A medium that transmits laser light, that is, a medium using a transparent substrate as a support, can easily measure the structural period,
There is a problem that the structure period cannot be measured in the case of using a mirror-like support that does not transmit laser light.

On the other hand, a technique for optically measuring the film thickness of a light-transmitting thin film sample is disclosed in Japanese Patent Application Laid-Open No. 5-231823. The technology described in the publication is such that monochromatic light is incident on a thin film sample, and its wavelength is continuously changed, so that interference fringes of reflected light from the front surface of the thin film sample and reflected light from the back surface of the thin film sample are obtained. Is generated, and the film thickness is measured by automatically detecting the peak position of the interference fringe.

However, according to the technique described in the publication, the film thickness is measured by automatically detecting the interference fringe peak of the reflected light while continuously changing the wavelength. In the method, there is a problem that it takes time to measure the film thickness and the mechanism of the apparatus becomes complicated.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances of the prior art, and provides a reversible thermosensitive recording material in a reversible thermosensitive recording medium using a mirror-like support that does not transmit laser light. An object of the present invention is to provide an optical film structure measuring device capable of easily measuring the structure period. Another object of the present invention is to provide an optical film structure measuring device capable of instantaneously performing the above measurement. Another object of the present invention is to provide a film thickness measuring device capable of instantaneous measurement with a simple device.
Another object of the present invention is to provide a novel distance measuring method using the film thickness measuring device.

[0009]

According to the present invention, in order to solve the above-mentioned problems, there is provided an apparatus for optically measuring a film structure of a sample having a light transmitting property, the surface of a base on which the sample is placed. A sample stage formed on a specular light-reflecting surface, a laser light source that is a light source for irradiating the sample and is spaced apart from the sample stage, and a light detector disposed on the same side as the laser light source facing the sample stage. There is provided an optical film structure measuring device characterized by comprising: Further, according to the present invention, in the above structure, the photodetector comprises a plurality of sensors for measuring scattered intensity of laser light, which are fixedly arranged at different detection angles of scattered light. A structure measuring device is provided. Further, according to the present invention, there is provided a device for optically measuring the film thickness of a sample having a light-transmitting property, wherein the surface of the table on which the sample is mounted is a specular light reflecting surface, A laser light source, which is a light source for irradiating a sample, which is spaced apart from the sample stage, and a laser light source which faces the sample stage, are arranged on the same side to display interference fringes formed by scattered light from the sample. There is provided a film thickness measuring device comprising: Further, according to the present invention, using the film thickness measuring device having the above configuration,
A method for optically measuring the film thickness of a sample having optical transparency, in which laser light is vertically irradiated to the sample placed on the sample table, and interference due to scattered light from the sample A film thickness characterized by forming a fringe on the screen, measuring the diameter of the innermost interference fringe among the interference fringes formed on the screen, and determining the film thickness of the sample based on the measurement result. A measurement method is provided. Furthermore, according to the present invention, with respect to a sample having a predetermined film thickness having light transmittance, which is placed between a laser light source which is a light source for irradiating a sample and a light reflecting surface,
Laser light is vertically irradiated by the laser light source, and interference fringes due to scattered light from the sample are formed on a screen arranged on the same side as the laser light source facing the reflecting surface, and formed on the screen. Among the interference fringes, the diameter of the innermost interference fringe is measured, and the distance between the reflection surface and the sample is obtained based on the measurement result, and a distance measuring method is provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. FIG. 1 is a diagram schematically showing a structural example of an optical film structure measuring apparatus according to the present invention. As shown in the figure, in this apparatus, the surface of the sample table 2 is formed as a specular light reflecting surface, the laser oscillator 3 is arranged on the upper side of the sample table 2, and the laser oscillator 3 and the laser oscillator 3 are arranged on the sample table 2. The photodetector 4 is arranged on the same side. In the figure, 1 is a sample (reversible thermosensitive recording material). The laser oscillator 3 is a He-Ne laser, A
A laser using an r laser, a He-Cd laser, or the like is used. As the sample table 2, for example, a transparent plastic film on which a metal such as Al, Ni, Pt, or Au is deposited, a transparent glass on which a metal such as Al, Ni, Pt, or Au is deposited, or the like can be used. The base (not shown) on which the sample table 2 is installed is preferably a hot plate or the like that can heat the sample 1 to near the color development temperature. The photodetector 4 comprises a plurality of sensors for measuring the intensity of the laser light scattered by the sample 1, which are fixedly arranged at different angles of the scattered light. Examples of the sensor that can be used for the photodetector 4 include a photodiode and a CCD image sensor. The sensor spacing is 0.5
It is desirable to set every 5 to 5 °, preferably 0.5 to 1 °. The measurement time by the sensor is preferably about 1/30 to 1 second.

When the structural period of the reversible thermosensitive recording material is measured by the apparatus of this structural example, the sample table 2 is placed on the base plate made of a hot plate (not shown), and the laser beam is applied to the sample 1 by the laser oscillator 3. The light is applied vertically, and the light scattered at the sample surface at that time is measured by the photodetector 4. This makes it possible to easily measure the structural period of the reversible thermosensitive recording material using a support that does not transmit laser light on the mirror surface. Further, by using as the photodetector 4 a plurality of sensors fixedly arranged at different angles of scattered light, it is possible to measure instantaneously.

Here, the "structural period" of the reversible thermosensitive recording material which is the object of the measurement of the present invention will be explained. The structural period can be considered as an amount representing the size of the phase separation structure. For example, in a phase-separated structure in which substance A forms a spherical domain in substance B as schematically shown in FIG. 3A, consider a cross section taken along the dotted line in FIG. 3A. Then, as shown in FIG. 3B, the compositions of the substance A and the substance B can be grasped in a cyclically changed form. This period A is called a structural period. This structural period cannot be captured in any phase-separated structure, and can be captured when the following factors are comprehensively satisfied, and is a meaningful numerical value. (1) The phase-separated structure has regularity with some order and has a characteristic structural period. (2) The volume ratio of substance A and substance B should not be extremely large or small in the structure. (3) Substance A and substance B are clearly separated to some extent in the structure.

In the case of the reversible thermosensitive recording material to be measured according to the present invention, substance A in FIG. 3 may be replaced by an organic low molecular substance, and substance B may be replaced by a resin matrix, and these substances may be replaced in the thermosensitive layer. When the above-mentioned factors (1), (2) and (3) are comprehensively satisfied, the concept of the structural period is effective. However, it is not clear how much each of the factors (1), (2), and (3) above should be satisfied.

A light scattering measurement method used for structural analysis of organic polymer compounds is effective as a method of capturing such a structural period. Figure 4 shows the method of measuring light scattering.
As schematically shown in (a), the sample light source a irradiates the sample c on the sample table b with light, and the transmitted light is projected onto the projection surface d,
The structure period is calculated based on the scattering angle obtained from the pattern, and the relationship between the scattering angle and the structure period Λ is given by the equation (1) (Equation 1).

[Equation 1] Where λ is the wavelength of the light source [μm], D is the refractive index of the sample
[−] And θ are scattering angles [deg].

Laser light is generally used as a light source used for measurement, and He--Ne laser is most often used. When a sample satisfying the above conditions (1), (2), and (3) is applied to the optical film structure measuring apparatus, the scattered light has a ring-shaped light intensity distribution as shown in FIG. 4 (a). Show. When the scattered light intensity is plotted against the scattering angle, FIG.
A curve having an intensity peak value at a certain angle as shown in (b) is shown. The value obtained by substituting the angle θm at this peak value into the equation (1) becomes the structural period Λm peculiar to the sample.

Next, the optical film structure measuring apparatus of the present invention will be described more specifically. In the device configuration of FIG. 1, a He-Ne laser oscillator is used as the laser oscillator 3,
As the photodetector 4, one in which 42 photodiodes were fixedly arranged over a scattering angle of 10 ° to 26 ° was used, and the scattering intensity output of the following sample was measured. The result is shown in FIG. The measurement time (1 scan) is 1/3
0 seconds. Sample: As the sample table 2, a 50 μm thick transparent film having Al vapor-deposited on its surface was used. A heat-sensitive recording layer having a thickness of 10 μm was provided thereon as Sample 1 according to the following formulation. (Formation Formula of Thermosensitive Recording Layer) Eicosane Diacid 4 parts Lignoceric acid 3 parts Behenic acid 1 part Vinyl chloride-vinyl acetate copolymer 32 parts Tetrahydrofuran 167 parts Toluene 55 parts

Next, as a test sample, a reversible thermosensitive recording layer was provided on a support, which was a 50 μm thick transparent film on which Al was deposited, to prepare a reflection type test sample. About 10 kinds of test samples having different structures of the reversible thermosensitive recording layer were prepared. As a test sample for comparison, a transmissive test sample was prepared by providing a 50 μm thick transparent film as a support and providing a reversible thermosensitive recording layer thereon. This test sample had the same coating conditions as those of the reflection type test sample, and was used as a reversible thermosensitive recording layer having the same structure. In FIG. 6, 2
1 is a hot plate, 22 is a reflective sample, 23 is a screen, 24 is a hole, 25 is a He-Ne laser oscillator, and the hot plate 21 is heated to 100 ° C. The interval was set to 40 mm, and the scattering intensity peak angle of the scattered light was measured by visually observing or photographing the pattern reflected on the screen 23. Further, in FIG. 7, 31 is a hot plate, 32 is a transmission type sample, 33 is a He—Ne laser oscillator, and 34.
Is a mirror, 35 is a hole, 36 is a photodetector, and the hot plate 3
The sample was heated to 100 ° C. in 1 and the photodetector 36 was scanned by a goniometer (not shown) in the direction of the arrow in the figure.

Using the above-mentioned reflection type and transmission type test samples, the scattering intensity output was measured by the optical film structure measuring apparatus having the configurations shown in FIGS. 6 and 7, respectively, and the peak value of the scattering intensity was obtained. Then, the scattering intensity peak angles of both types of test samples were plotted as shown in FIG. 8 to check the correlation. As a result, the correlation shown by the solid line was obtained. The dotted line is the case where the correlation is 1. It can be seen from FIG. 8 that almost the same measurement results are obtained in the transmission type test and the reflection type test. It should be noted that the slight difference in FIG. 8 is considered to be an error caused by visual observation when the reflection type test sample was measured by the apparatus shown in FIG.

From the above, it can be seen that the structural period of a reversible thermosensitive recording material using a support that does not transmit laser light on a mirror surface can be easily measured by using the apparatus configuration as shown in FIG. .

Next, the film thickness measuring apparatus and method according to the present invention will be described. FIG. 9 is a diagram schematically showing a structural example of the film thickness measuring device according to the present invention. As shown in the figure,
In this apparatus, the surface of the sample table 42 on which the sample 41 is placed is formed as a specular light reflecting surface, a laser oscillator 43 is arranged above the sample table 42, and the same as the laser oscillator 43 with respect to the sample table 42. The screen 44 is arranged on the side. Reference numeral 45 denotes a hole formed in the screen, through which the laser light from the laser oscillator 43 passes. The sample 41 to be measured is in the form of a thin film having optical transparency. He-N as the laser oscillator 43
A laser using an e laser, an Ar laser, a He-Cd laser, or the like is used. Examples of the sample table 42 include a transparent plastic film on which a metal such as Al, Ni, Pt, and Au is deposited, and a transparent glass on which Al, Ni, and P are formed.
It is possible to use a material obtained by vapor-depositing a metal such as t or Au. As the screen 44, for example, frosted glass, semitransparent plastic, flattened trace paper, or the like can be used. The position of the screen 44 with respect to the surface of the sample table 42 is arbitrarily set on a surface perpendicular to the optical axis of the reflected light. However, in order to downsize the device and accurately capture the scattered light intensity, the position where the first interference fringes are strongest is preferable.

In the film thickness measuring apparatus of the present invention, the laser light from the laser oscillator 43 is vertically irradiated to the sample 41 through the hole 45 of the screen 44. Then, when the scattered light generated when the laser light passes through the sample 41 and the light that passes through the sample 41 and is reflected by the surface (reflection surface) of the sample table 42 passes from the back surface to the front surface of the sample 41. The generated scattered light interferes with each other to form an interference fringe on the screen 44. Here, as shown below, the diameter d of the innermost interference fringe (hereinafter also referred to as the first interference fringe) of the interference fringe and the sample 41.
It is known that there is a correlation with the film thickness of. Therefore, if the correlation (calibration curve) between the first interference fringes and the sample film thickness is obtained in advance, the sample film thickness can be obtained by measuring the diameter d of the first interference fringes. Incidentally, here, it is not necessary to change the wavelength as in the case of the above-mentioned Japanese Patent Laid-Open No. 5-231823.

Next, the relationship between the interference fringes and the sample film thickness will be described with reference to FIG. The laser light from the laser oscillator 43 is vertically incident on the sample (41) and is reflected by the reflection surface (the surface of the sample table 42), so that the scattered light causes interference fringes of radius r at the point C ′ on the screen 44. Are formed. This is formed by the scattered lights A and B at the points A ′ and B ′. In this case, the optical path
N times wavelength λ (n is an integer) between [A] and optical path [B]
Since the optical path difference of is considered necessary, the following equation holds. [B] − [A] = nλ (1) Here, from FIG. 10, [B] = √ {r ² + (h + l) ² }, [A]
= √ {r ² + (h-1) ² }, so substituting them into the equation (1), √ {r ² + (h + l) ² } -√ {r ² + (h-1) ² } = Nλ (2) Then, the following relational expression can be obtained by modifying the expression (2). r = √ {4 h ² l ² / n ² λ ² + n ² λ ² / 4- (h ² + l ² )} (3) where nλ is almost the same as the distance 2l of the scattering center of the film. Since n is very large, assuming that nλ is smaller than 2l by mλ (m is the stripe number (0,1,2 ...)), the equation (3) becomes the following equation. r = √ {4h ² l ² / (2l-mλ) ² + (2l-mλ) ² / 4- (h ² + l ² )} (4) From the formula (4), the scattering center in the film Position l is sought. l
Although the relationship between the film thickness and the film thickness differs depending on the sample, l has a substantially linear relationship with the film thickness. Therefore, by using this relationship and calibrating the relationship between the r and the film thickness by actual measurement, r (= d / 2)
It is understood that the film thickness of the sample is required when is determined.

Next, a specific example will be described. The same reversible thermosensitive recording material as prescribed above was applied to the aluminum vapor-deposited surface of a PET film (thickness 50 μm) on the surface of which aluminum was vapor-deposited while changing the film thickness to prepare a plurality of samples. Figure 9
The film thickness of these samples was obtained by measuring the diameter of the first interference fringes using a device as shown in FIG. The result is shown in FIG. The distance between the screen and the aluminum vapor deposition surface (reflection surface) is set to 49 mm, and the laser is H
e-Ne (wavelength 632.8 nm) was used.

From the above, it can be seen that the device configuration as shown in FIG. 9 has an advantage that the film thickness of the sample can be instantaneously measured with a simple device.

Next, the distance measuring method according to the present invention will be described. FIG. 12 is an explanatory diagram of the distance measuring method according to the present invention. In the figure, 51 is a thin film sample having optical transparency, 52
Is a movable stage that holds the sample 51 fixedly, and is movable in the direction of the arrow. Reference numeral 53 is a reflector, 54 is a laser oscillator, 55 is a screen, and 56 is a hole formed in the screen 55 so that the laser light from the laser oscillator 54 can pass therethrough. As the laser oscillator 54 and the screen 55, the same ones as those used in the film thickness measuring device described above can be used. The sample 51 can be provided on a transparent support plate made of, for example, plastic. As the reflection plate 53, the same one as that used as the sample table in the film thickness measuring device described above can be used.

According to the distance measuring method of the present invention, the distance between the reflector 53 and the sample 51 can be obtained as follows. That is, when the position of the sample 51 having a certain film thickness and having light transmittance is changed, the diameter of the first interference fringes formed on the screen 55 is also changed due to the scattering of the laser light, and there is a correlation between the two. There is. Therefore, if the correlation between the distance between the sample 51 having a certain film thickness and having the light transmittance and the reflection plate 53 and the diameter of the first interference fringes is checked in advance, The distance between the sample 51 and the reflector 53 can be obtained.

According to the distance measuring method of the present invention, even if the sample 51a is slightly bent as shown in FIG. 13A or the reflector 53b is slightly inclined as shown in FIG. Not affected. However, as shown in (c) of FIG.
When 1c is tilted, measurement becomes impossible. In these figures, 51b is a sample, 53a and 53c are reflectors, and 60
Reference numerals a, 60b, and 60c are laser lights.

Next, a specific example will be described. A sample was prepared by coating the surface of a PET film (film thickness 50 μm) with the same reversible thermosensitive recording material as prescribed above in a film thickness of 10 μm. Using this sample, with a device as shown in FIG.
The diameter of the first interference fringe at each position was measured by changing the position of the sample variously. The result is shown in FIG.
An aluminum vapor deposition mirror was used as the reflector. The distance between the reflection plate and the screen was set to 200 mm, and the laser used was He-Ne (wavelength 632.8 nm).

From the above, according to the distance measuring method of the present invention, there is an advantage that the distance between the sample and the reflector, which is relatively in motion and whose angle changes, can be instantaneously measured with a simple device. I understand.

[0030]

According to the optical film structure measuring apparatus of the first aspect of the present invention, since the sample table surface is made to be a specular light reflecting surface, the laser light is reflected, and the scattering intensity of the laser light is measured. It is possible to easily measure the structural period when the thermal recording material is applied to a base material having a mirror surface. Further, since the laser light is reflected and passes through the sample twice, the detection output is increased as compared with the transmission type device, and a thin film (10 μm or less) sample can be easily measured. According to the optical film structure measuring device of the second aspect, a plurality of sensors for measuring the scattered intensity of the laser light are fixedly arranged at different angles of the scattered light in the device, so that the structural period can be measured instantaneously. Claim 3
According to the film thickness measuring device and method of (4) and (4), the sample table surface is made to be a specular reflection surface and the laser beam is reflected to form the interference fringes on the screen, so that the sample film thickness can be instantly and easily measured. There are advantages. According to the distance measuring method of claim 5, there is an advantage that the distance between the sample and the reflector can be easily measured.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a structural example of an optical film structure measuring device according to the present invention.

FIG. 2 is a diagram schematically showing a structure of a conventional optical film structure measuring device.

FIG. 3 is an explanatory diagram of a structural period of a reversible thermosensitive recording material.

FIG. 4 is an explanatory diagram of a method for measuring light scattering.

FIG. 5 is a diagram showing an example of measurement results of scattering intensity output.

FIG. 6 is a diagram showing a measuring device for a reflective sample.

FIG. 7 is a view showing a measuring device for a transmission sample.

FIG. 8 is a diagram showing a correlation of scattering intensity peak angles of the samples measured in FIGS. 6 and 7.

FIG. 9 is a diagram schematically showing a structural example of a film thickness measuring device according to the present invention.

FIG. 10 is an explanatory diagram of the relationship between interference fringes and sample film thickness.

11 is a diameter of the first interference fringes measured by the device of FIG. 9,
It is a figure which shows the relationship with a sample film thickness.

FIG. 12 is an explanatory diagram of a distance measuring method according to the present invention.

FIG. 13 is a diagram showing a relationship between a reflector and a sample.

14 is a diagram showing the relationship between the diameter of the first interference fringes measured by the device of FIG. 12 and the distance between the sample and the reflector.

[Explanation of symbols]

1 sample 2 sample stage 3 laser oscillator 4 photodetector 41 sample 42 sample stage 43 laser oscillator 44 screen 51 sample 52 movable stage 53 reflector 54 laser oscillator 55 screen

Claims (5)

[Claims] 1. A device for optically measuring a film structure of a sample having optical transparency, comprising: a sample table having a mirror-reflecting surface as a table surface on which the sample is mounted; An optical film structure measuring apparatus comprising: a laser light source, which is a light source for irradiating a sample, which is spaced apart from each other, and a photodetector, which is disposed on the same side as the laser light source facing the sample stage. 2. The optical film structure according to claim 1, wherein the photodetector comprises a plurality of sensors for measuring scattered intensity of laser light, which are fixedly arranged at different detection angles of scattered light. measuring device. 3. An apparatus for optically measuring the film thickness of a sample having optical transparency, comprising a sample table having a mirror-reflecting surface as a table surface on which the sample is placed, and the sample table. A laser light source, which is a light source for irradiating the sample, which is spaced apart from each other, and a screen which is disposed on the same side as the laser light source facing the sample stage and displays an interference fringe formed by scattered light from the sample. A film thickness measuring device comprising. 4. A method for optically measuring the film thickness of a sample having optical transparency using the film thickness measuring device according to claim 3, wherein the sample mounted on the sample table is Laser light is vertically irradiated to form interference fringes due to scattered light from the sample on the screen, and the diameter of the innermost interference fringe among the interference fringes formed on the screen is measured. A film thickness measuring method, wherein the film thickness of the sample is obtained based on 5. A laser light source vertically irradiates a sample having a predetermined film thickness having a light transmitting property, which is placed between a laser light source which is a light source for irradiating a sample and a light reflecting surface, An interference fringe due to scattered light from the sample is formed on a screen arranged on the same side as the laser light source facing the reflecting surface, and the diameter of the innermost interference fringe among the interference fringes formed on the screen is defined as A distance measuring method characterized by measuring and measuring the distance between the reflecting surface and the sample based on the measurement result.