JP2009058267A - Silver deposition film thickness measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring inexpensively and continuously silver deposition having a film thickness more similar to a metal plate, by solving the problems wherein the film thickness is required to be controlled because silver is expensive and thereby increase of thickness cannot be adopted as the only target, whereas the deposition film thickness for a reflection film is required to have the film thickness of 100 nm or more which is a film thickness more similar to a metal plate differently from a translucent metal deposition film thickness of about 30-60 nm for raising moisture impermeability of the film, and especially for a reflection film for liquid crystal display, a reflection efficiency is required to be heightened as much as possible, and it is known that silver deposition can acquire the highest reflectivity in a visible light domain. <P>SOLUTION: A silver deposition film formed on a transparent substrate is irradiated with an ultraviolet ray in the range of 310-340 nm, and film thickness measurement of the silver deposition film in the range of 100-400 nm is performed based on correlation between the transmittance and the silver deposition film thickness. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for measuring a deposited film thickness of silver. In particular, the present invention relates to a method for measuring a deposited silver film thickness for a reflective film.

  Examples of the method for measuring the film thickness of a deposited film continuously deposited on a polymer film running in a vacuum chamber include, for example, a visible light transmission method, a resistance value measurement method, an eddy current method, or a crystal resonator method. and so on.

The visible light transmission method measures from the amount of light that has passed through the measurement object, and the measurement object in this case is a vapor deposition film and a polymer film (Patent Document 1). In the eddy current method, a high-frequency current is passed through a measuring element to generate an eddy current in a deposited film, and an eddy current that varies depending on the thickness is measured. In this case, the conductivity of the deposited film is measured. The resistance value measurement method measures an electrical resistance value between contacts, and in this case, the resistance of the deposited film between two conductive rollers is measured. In the crystal oscillator method, the film thickness is obtained by measuring a change in vibration frequency caused by the deposition film adhering to the crystal oscillator. In this method, the film thickness deposited on the quartz resonator in the vicinity of the vapor deposition region is measured.
JP-A-6-82220

The vapor deposition film thickness for the reflective film is closer to the metal plate than the vapor deposition film thickness of about 1000 mm or more, unlike the translucent metal film thickness of about 300 mm (angstrom) to 600 mm for increasing the moisture permeability of the film. The film thickness is required. Particularly for reflective films such as liquid crystal displays, it is required to increase the reflection efficiency as much as possible, and it is known that silver deposition has the highest reflectance in the visible light region. However, since silver is expensive, the thicker the film, the better. The film thickness must be controlled.
However, any of the visible light transmission method, resistance measurement method, and eddy current method has a drawback that the sensitivity is high in the semi-transparent metal vapor deposition film thickness portion, and the sensitivity decreases when the film thickness is close to the metal plate. In addition, the crystal resonator method has a drawback that an expensive crystal resonator must be frequently replaced.
The problem to be solved is to provide a method for continuously and inexpensively measuring silver deposition having a film thickness closer to that of a metal plate.

The present invention irradiates a silver vapor deposition film formed on a transparent substrate with ultraviolet light in the range of 310 nm to 340 nm, and the silver vapor deposition film of 100 nm to 400 nm depending on the correlation between the light transmittance and the silver vapor deposition film thickness. It is intended to provide a method for measuring the thickness of a silver deposited film characterized by measuring the thickness of the film.
In addition, the silver vapor deposition film formed on the transparent substrate is irradiated with ultraviolet light in the range of 310 nm to 340 nm, and the silver vapor deposition of 100 nm to 400 nm is performed according to the linear relationship between the logarithmic value of the light transmittance and the silver vapor deposition film thickness. The present invention provides a silver vapor deposition film thickness measuring method characterized by measuring the film thickness of a film.

The method for measuring the thickness of a silver deposited film according to the present invention can irradiate ultraviolet light in the range of 310 nm to 340 nm, and can measure the film thickness of the thick film of silver deposited by the correlation between the light transmittance and the silver deposited film thickness. There is an advantage that silver deposition suitable for a reflective film is easily and inexpensively manufactured.

The transparent substrate described in the present invention refers to a transparent plastic film excellent in continuous film-forming properties such as polyolefin, polyester, polyamide, polycarbonate, acrylic resin, etc., but plastic substrate, soda lime silica composition glass or borosilicate glass (non-alkali) It can also be applied to known glass substrates such as glass.
In particular, the biaxially oriented polyester film is preferable because it has excellent properties such as dimensional stability, mechanical properties, heat resistance, transparency, and electrical properties.
Moreover, in order to improve the vapor deposition adhesion of the transparent substrate, for example, a surface activation method for performing surface corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, etc., a surface etching method with a chemical such as acid, alkali, aqueous amine solution, Alternatively, various resins such as an acrylic resin, a polyester resin, a urethane resin, and a polyolefin resin having adhesiveness may be provided on the film surface as a primer layer.
Further, if necessary, other particles such as kaolin, talc, silicon dioxide, calcium carbonate, titanium dioxide, zeolite, aluminum oxide and the like may be blended in a small amount without departing from the spirit of the present invention. In addition, a weathering agent, an antistatic agent, a lubricant, an antioxidant and the like may be blended.

The silver deposited film described in the present invention can be formed by a normal metal thin film forming method such as vacuum deposition, sputtering, or ion plating, and includes an alloy or a mixture of silver, silver and other metals. Includes all of the silver deposited film. Discoloration can be prevented by including, for example, copper, platinum, palladium, iridium, zinc, tin and the like in silver.
In the present invention, the transparent substrate is left in a space with a vacuum degree of 10 ⁻² Torr or less and dried in a vacuum to sufficiently remove volatile substances such as water, oxygen, nitrogen, hydrocarbon gas, etc. present in the flat film. It is preferable to keep it. As a result, there is little change in the degree of vacuum during the vapor deposition operation, and vapor deposition under stable conditions becomes possible.
On the silver vapor-deposited film, as a protective film, a vapor-deposited film such as aluminum oxide, zirconium oxide, titanium oxide, tin-indium-zinc alloy, polyester-based resin, silicon alkyd resin, retil-type titanium oxide and carbon black are contained. A coating film such as a thermosetting moisture-proof paint and a corrosion inhibitor mainly composed of a vaporizable rust preventive agent is provided, and the environmental resistance can be improved while maintaining a good reflectance by this protective film.

In the present invention, a silver vapor deposition film formed on a transparent substrate is irradiated with ultraviolet light in the range of 310 nm to 340 nm, and the film thickness of silver vapor deposition is measured by the correlation between the light transmittance and the silver vapor deposition film thickness. . The light transmittance can also be determined by (light intensity through a transparent substrate with a silver vapor deposition film) / (light intensity through a transparent substrate).
The light transmittance can be measured by a general spectral transmittance measuring device. The spectral transmittance measuring device applies light emitted from a light source to a diffraction grating or a prism, and extracts an arbitrary monochromatic light depending on an angle based on the principle of Bragg scattering. At this time, (1 / integer) light of the target wavelength also comes out together, so the light emitted from the light source is applied to the grating through the filter.
A general spectral transmittance measuring instrument has a wavelength range of about 100 nm to 1000 nm, and measures the transmittance over a wide range of ultraviolet light, visible light, and infrared light. However, in the case of the present invention, since one deuterium lamp capable of setting the wavelength from 160 nm to 400 nm is prepared, the measuring instrument can be downsized. Easy management of consumable lamps.

  Alternatively, the film may be irradiated with a lamp that emits ultraviolet light, for example, a deuterium lamp without spectroscopy, and the film thickness of silver vapor deposition may be measured by the correlation between the light transmittance at that time and the film thickness of silver vapor deposition. Absent. In order to narrow the wavelength in the range from 310 nm to 340 nm, a filter may be used. In any case, by eliminating a spectroscopic device such as a diffraction grating or a prism, the measuring device can be reduced in size and cost.

Hereinafter, the silver vapor deposition film thickness measuring method described in the present invention will be described.
First, a transparent plastic film for a reflective film, and a film with a silver vapor deposited film on the film before and after the silver vapor deposited film that provides the desired reflectance. With the apparatus, the transparent substrate material, the degree of vacuum, and the film forming conditions such as film forming speed are made the same.
Next, ultraviolet rays in the range of 310 nm to 340 nm are dispersed and irradiated, and a graph is created in which the light transmittance with respect to the wavelength at that time is plotted for each film thickness of silver.
Next, within the range of wavelengths, one or a range of wavelengths that can be measured for the light transmittance of the deposited film thickness of each silver is set, and the light transmittance for that wavelength with respect to the thickness of the deposited film of each silver Seeking the relationship.
Thereby, the film thickness of a silver vapor deposition film can be measured.
In addition, it is confirmed that the film thickness of the silver vapor deposition film can be measured with high accuracy by using a logarithmic display of the light transmittance with respect to the film thickness to find out that the linear regression is performed.

As a transparent substrate, a biaxially oriented polyester film having a film thickness of 50 μm is used, and as a film formation method for silver, the film thickness is determined by a vacuum deposition method with a vacuum degree of 5 × 10 ⁻² Pa and a film formation rate of 40 m / min. Prepare around 1000cm. FIG. 1 is a graph showing the relationship between the silver deposited film thickness and the reflectance, and it can be seen that the reflectance is saturated when the silver deposited film thickness is about 1000 mm or more.
Next, a graph in which ultraviolet light in the range of 310 nm to 340 nm is scattered and irradiated before and after the silver vapor deposition film thickness at which the reflectance is saturated, and the light transmittance with respect to the wavelength at that time is plotted for each silver film thickness. Create
FIG. 2 is a graph showing the relationship between the silver deposited film thickness and the light transmittance. It can be seen that the peak of the light transmittance value is in the range of 310 nm to 340 nm. Therefore, it can be seen that the silver deposited film thickness can be substantially measured from the value of light transmittance in this wavelength range. FIG. 3 is a graph showing the relationship between the silver deposited film thickness and the light transmittance at a wavelength of 314 nm, for example, and the silver deposited film thickness can be specified along this line.
FIG. 4 shows the result of logarithmic display of the light transmittance with respect to the film thickness in FIG.
The logarithmic value of the light transmittance is almost linear with respect to the film thickness value, and the equation of the regression line is obtained as the following mathematical formula 1 (M: light transmittance%, N: film thickness Å). Moreover, the correlation coefficient of Formula 1 is −0.999938, indicating a strong negative correlation.

Therefore, by linearly displaying the light transmittance with respect to the film thickness, it is possible to perform a linear regression, and thus the film thickness of the silver deposited film can be measured with high accuracy.
FIG. 5 is a plot of the correlation coefficient between the film thickness value and the logarithmic value of the light transmittance. The correlation coefficient between wavelengths of 310 nm and 334 nm is 0.83 or more, and silver deposition is accurately performed in this wavelength range. It shows that the film thickness of the film can be measured. Further, from this result, the film thickness can be accurately measured in a wide wavelength range of about 310 nm to 334 nm even if the specific wavelength is not limited.

The relationship between a silver vapor deposition film thickness and a reflectance is shown. The relationship between silver vapor deposition film thickness and light transmittance is shown. The relationship between the silver vapor deposition film thickness and light transmittance at 314 nm is shown. The relationship of the silver vapor deposition film thickness in 314 nm and the light transmittance logarithm display is shown. The relationship between each wavelength and the correlation coefficient is shown.

Claims (2)

  Irradiation of the silver vapor deposition film formed on the transparent substrate with ultraviolet light in the range of 310 nm to 340 nm, and measurement of the film thickness of the silver vapor deposition film of 100 nm to 400 nm based on the correlation between the light transmittance and the silver vapor deposition film thickness. A method for measuring a deposited film thickness of silver, characterized in that:   The silver vapor deposition film formed on the transparent substrate is irradiated with ultraviolet light in the range of 310 nm to 340 nm, and the silver vapor deposition film of 100 nm to 400 nm has a linear relationship between the logarithmic value of the light transmittance and the silver vapor deposition film thickness. A method for measuring the thickness of a deposited silver film, comprising measuring the film thickness.

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