JP2001181850A - Method of continuous film deposition using atmospheric pressure plasma - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform inline measurement of a thin film deposited on a substrate. SOLUTION: The inline measurement of the thickness of a thin film deposited on a substrate S is performed by providing a light source 2 for irradiating a substrate S having a deposited film with light, a spectrometer 3 for spectrally diffracting the reflected light reflected by the substrate S, an optical multichannel analyzer 4 for detecting the spectrally diffracted light, and a computer 5 for computing the thickness of the thin film on the basis of the output of the analyzer 4. Further, the film thickness can be held constant by performing feedback control on the basis of the resultant measured value of the film thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a continuous film formation method using normal pressure plasma, and more particularly, to a continuous film formation method using normal pressure plasma in which a discharge plasma treatment is performed in a mixed gas atmosphere capable of forming a thin film such as silicon dioxide or titanium dioxide. Related to the membrane method.

[0002]

[Prior art]

Conventionally, continuous deposition of thin films such as silicon dioxide and titanium dioxide using atmospheric pressure plasma has been devised from the viewpoint of economy and production operability of production equipment as compared with vapor deposition and sputtering. is there. FIG. 1 shows an example of a discharge plasma processing apparatus for performing such a continuous film forming method.

In the discharge plasma processing apparatus shown in FIG. 1, a roll electrode 10 and a curved electrode 20 having a coaxial cylindrical surface (concave surface) opposed to the surface of the roll electrode 10 at a predetermined interval are arranged to face each other. A counter electrode in which a discharge space 30 curved at substantially equal intervals is formed between the roll electrode 10 and the curved electrode 20, and a mixed gas containing a reaction gas is supplied from one end of the discharge space 30 and from the other end. The roll electrode 10 and the curved electrode 20 are evacuated by an exhaust device using a flow control valve 40 and a vacuum pump 50, and the suction and exhaust amount is adjusted so that the mixed gas flow rate in the discharge space 30 becomes constant. Is applied to generate a plasma discharge to form a thin film on a base material (not shown) running along the roll electrode 10 (for example, Japanese Unexamined Patent Application Publication No. 11-241165).

[0004]

[Problems to be solved by the invention]

By the way, when the purpose of forming a thin film is to improve the wettability of the surface of a base material, the uniformity of the treatment does not pose a particularly serious problem as long as the effect is exerted on the entire treated surface. On the other hand, when forming an anti-reflective film, a high-reflection film, or an optical thin film such as a filter, there is a serious problem that processing unevenness affects the overall performance. That is, when the purpose is to form an optical thin film, unevenness in the thickness of the thin film appears to human eyes as uneven color. The deviation of the reflection wavelength at which this color unevenness can be ignored is 20
It is said to be about nm.
It is necessary to suppress film thickness unevenness within ± 10% corresponding to a film thickness of about 100 to 200 nm.

However, in the continuous film forming method using the apparatus shown in FIG. 1, unreacted powder of a reaction gas such as a metal oxide or an organometallic compound generated in the discharge space 30 is supplied to the exhaust-side pipe, It adheres and accumulates in the suction flow paths of the control valve 40 and the vacuum pump 50 and the like.
May fluctuate. In addition, by depositing unreacted powder of a reactive gas such as a metal oxide or an organometallic compound on the surface of the curved electrode 20 on the opposite side of the substrate,
The dielectric constant of the curved electrode 20 side may fluctuate, and there is a problem that the discharge state changes and the film thickness of the continuously formed thin film fluctuates due to these factors.

In order to solve such a problem, the film thickness may be controlled by measuring the film thickness of the thin film. However, the conventional device cannot measure the film thickness in-line, and after the film formation, , It is necessary to measure the reflectance spectrum with a spectrophotometer or the like to calculate the film thickness. Therefore, the film thickness cannot be controlled in-line.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a continuous film forming method using normal pressure plasma, which can measure a thin film formed on a substrate in-line. And

[0008]

[Means for Solving the Problems]

The present invention, under a pressure near the atmospheric pressure, in a mixed gas atmosphere,
In a continuous film forming method for forming a thin film on a substrate by performing a discharge plasma treatment, a light source that irradiates light on the formed substrate and a spectroscope that disperses light reflected by the substrate. , An optical multi-channel analyzer that detects the separated light, and a computer that calculates the thickness of the thin film based on the output of the analyzer, and measures the thickness of the thin film formed on the base material in-line. It is characterized by doing.

In the continuous film forming method of the present invention, the film thickness is controlled by feeding back a difference between the film thickness of the thin film calculated by a computer and a preset film thickness to a thin film generation control system. It may be.

According to the continuous film forming method of the present invention, a reflection spectrum from a substrate on which a film is formed can be obtained instantaneously, so that the thickness of a thin film can be calculated in-line. In addition, by performing feedback control on the difference between the calculated value of the film thickness and the target value (the film thickness set value), the film thickness can be precisely controlled in-line.

Here, in the continuous film forming method using normal pressure plasma of the present invention, the pressure near the atmospheric pressure means 13300 to 10640
It means a pressure of 0 Pa, and particularly preferably a pressure range of 93100 to 103740 Pa which facilitates pressure adjustment and facilitates device configuration.

As the mixed gas used in the present invention, a mixed gas composed of a source gas, a reaction gas and a diluent gas is suitable. The content ratio of the source gas in the mixed gas is preferably 0.01 to 5% by volume.

The source gas is a source gas for a thin film to be formed on a base material, for example, a reactive organic silicon compound such as tetramethoxysilane, tetraethoxysilane, methyltriethoxysilane, tetramethylsilane, tetraethylsilane, or the like; Reactive organic titanium compounds such as titanium isopropoxide and titanium butoxide, carbon tetrafluoride (CF4), carbon hexafluoride (C2 F6), propylene hexafluoride (CF3 CFCF)
2), fluorine such as octafluorocyclobutane (C4 F8)
Reactive fluorine compounds such as carbon compounds, halogen-carbon compounds such as monochlorocarbon trifluoride (CCIF3), and fluorine-sulfur compounds such as sulfur hexafluoride (SF6).

In the present invention, a hydrophilic polymer film can also be deposited by performing discharge plasma treatment in an atmosphere of a monomer having a hydrophilic group and a polymerizable unsaturated bond in the molecule. Examples of the hydrophilic group include a hydroxyl group, a sulfonic group, a sulfonic group, a primary or secondary or tertiary amino group, an amide group, a quaternary ammonium group, a carboxylic group, and a hydrophilic group such as a carboxylic group. No. Further, even when a monomer having a polyethylene glycol chain is used, a hydrophilic polymer film can be similarly deposited.

The above-mentioned monomers include acrylic acid, methacrylic acid, acrylamide, methacrylamide, N, N-dimethylacrylamide, sodium acrylate, sodium methacrylate, potassium acrylate, potassium methacrylate, sodium styrenesulfonate, allyl alcohol, Allylamine, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate and the like can be mentioned. These monomers may be used alone or as a mixture of two or more.

Since the above-mentioned hydrophilic monomer is generally a solid, it is used after being dissolved in a solvent and vaporized by means such as reduced pressure.
Examples of the solvent include organic solvents such as methanol, ethanol, and acetone, water, and mixtures thereof.

The source gas used in the present invention may include a metal-containing gas. As the metal, the aforementioned S
In addition to i and Ti, for example, Al, As, Bi, B, Ca,
Cd, Cr, Co, Cu, Ga, Ge, Au, In, I
r, Hf, Fe, Pb, Li, Na, Mg, Mn, H
g, Mo, Ni, P, Pt, Po, Rh, Sb, Se,
Examples include metals such as Sn, Ta, Te, V, W, Y, Zn, and Zr. Examples of the gas containing these metals include metal organic compounds, metal-halogen compounds, metal-hydrogen compounds,
Processing gases such as metal-halogen compounds and metal alkoxides are exemplified. These may be used alone or 2
More than one kind may be used in combination.

The source gas used in the present invention is appropriately selected and used according to the intended thin film, and is not limited to those listed above.

The reaction gas generates a compound constituting a target thin film by reacting with a raw material gas or facilitates the generation thereof. For example, oxygen gas, ozone, water (steam), Organic compounds containing elemental oxygen, such as carbon monoxide, carbon dioxide, nitric oxide, nitrogen dioxide, alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, and aldehydes such as methanal and ethanal, nitrogen Gas, ammonia, sulfur dioxide, sulfur trioxide and the like. The content ratio of the reaction gas in the mixed gas is preferably from 0 to 99.99% by volume.

The diluent gas is used to control the degree of reaction between the source gas and the reaction gas and the properties of the formed inorganic thin film. For example, helium, argon, neon, and nitrogen gas having low activity are used. And the like. These may be used alone or in combination of two or more. The content ratio of the dilution gas in the mixed gas is preferably from 0 to 99.99% by volume.

The discharge plasma processing apparatus for performing the continuous film forming method of the present invention is not particularly limited as long as it can generate uniform discharge plasma in the above-mentioned mixed gas atmosphere under a pressure near atmospheric pressure. Although not limited thereto, for example, a discharge plasma generator having a counter electrode of a parallel plate type, a cylindrical opposed plate type, a spherical opposed plate type, a hyperboloid opposed plate type, a coaxial cylindrical type or the like can be used. Among them, as shown in FIG. 1, a roll electrode 10 and a curved electrode 20 having a coaxial cylindrical surface (concave surface) opposed to the surface of the roll electrode 10 at a constant interval.
And the roll electrode 10 and the curved electrode 2
A discharge plasma generator provided with a counter electrode in which a discharge space 30 curved at substantially equal intervals between 0 and 0 is particularly preferable. The counter electrode includes a roll electrode 10 and a curved electrode 20.
Is a film forming space.

The above-mentioned roll electrode is a columnar or cylindrical electrode, and the conductive material forming the electrode body is preferably a metal such as copper or aluminum, or an alloy or intermetallic compound such as stainless steel or brass. And the like.

The distance between the roll electrode and the curved electrode is not particularly limited as long as it is equal to or greater than the thickness of the support or base material of the thin film formed by the discharge plasma treatment. And the uniformity of the discharge is easily impaired. Further, it is preferable that the thickness be 5 mm or less because there is a possibility that the damage of the support material or the base material may increase. Also, (interval between roll electrode and curved electrode) / (radius of roll electrode)
Is preferably 1/100 or less because the smaller the value, the better the uniformity of discharge.

It is preferable that at least one surface of the roll electrode and the curved electrode, particularly the surface of the curved electrode, is coated with a solid dielectric. When at least one of the roll electrode and the curved electrode is coated with the solid dielectric as described above, the film formation space is defined as a space between the exposed electrode surface and the solid dielectric coated surface or a space between the solid dielectric coated surfaces. Become.

Examples of the solid dielectric include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass,
Silicon dioxide, aluminum oxide, zirconium dioxide,
Examples thereof include metal oxides such as titanium dioxide and double oxides such as barium titanate.

The relative permittivity of the solid dielectric is preferably 10 or more. When the relative dielectric constant is 10 or more, high-density discharge plasma can be generated at a low voltage, and a short-time surface treatment or high-speed front / back treatment can be performed. It becomes difficult to perform a proper surface treatment. The upper limit of the relative permittivity is not particularly limited, but about 18500 realized materials are known.

The relative permittivity of the solid dielectric is particularly preferably in the range of 10 to 100. Examples of such a solid dielectric include zirconium dioxide (ZrO2) and titanium dioxide (TiO2).
Metal oxides such as barium titanate (Ba2 TiO4)
And the like.

Titanate compounds are known as ferroelectrics,
2 In the case of a single substance, the relative permittivity differs depending on the crystal structure, and the relative permittivity is about 80 in the rutile type crystal structure.

In the case of a compound of TiO 2 and at least one selected from oxides of metals such as Ba, Sr, Pb, Ca, Mg, and Zr, the relative dielectric constant is about 2000 to 18500, The dielectric constant can be changed depending on purity and crystallinity.

On the other hand, when TiO 2 alone is used, the composition changes drastically under a heating environment. For example, when heating is performed in a reducing atmosphere, the use environment is limited due to the occurrence of oxygen deficiency and the like. Since a thin film of about 10 ⁴ Ω · cm is formed, it is easy to shift to arc discharge by applying a voltage, and care must be taken. Therefore, it is better to use TiO2 containing aluminum oxide (Al2 O3) than to use it alone. In particular, TiO2: 5 to 50% by weight, Al2 O3: 50 to 9
5% by weight mixed metal oxide thin film, or ZrO2
Comprising a metal oxide thin film having a thickness of 10 to 10
A solid dielectric of 00 μm is more preferable because it is thermally stable, has a relative dielectric constant of about 10 to 14 and a specific resistance of about 10 ¹⁰ Ω · cm, and does not generate arc discharge.

The shape of the solid dielectric may be sheet-like or film-like, but preferably has a thickness of 0.05 to 4 mm. If it is too thick, high voltage is required to generate discharge plasma,
If it is too thin, dielectric breakdown occurs when a voltage is applied, and arc discharge occurs.

In the discharge plasma processing apparatus embodying the present invention, the roll electrode may be configured to rotate in synchronization with the transport speed of the substrate on which the inorganic thin film is formed. The method of rotating the roll electrode may be a method of rotating in conjunction with the base material by free driving, or a method of rotating by a driving device such as a motor.

In the discharge plasma processing apparatus embodying the present invention, the gas introduction port is provided on the substrate carrying side of the plasma space, and extends from the curved electrode toward the roll electrode and along the transport direction of the substrate. It is preferable that the gas be introduced into the chamber.

The material of the gas inlet is not particularly limited,
In the case of a conductive material such as a metal, it is preferable to provide an insulator between the counter electrode and the gas inlet in order to prevent discharge between the counter electrode and the gas inlet.

Although the structure of the gas inlet is not particularly limited,
For example, a jet nozzle system using a pressure pump may be used. Also, a swash plate facing the gas introduction direction is provided,
The gas supply passage is gradually narrowed to provide a constriction near the gas inlet, and after passing through the constriction, the mixed gas is diffused and, at the same time, the mixed gas flow is changed substantially parallel to the substrate transport direction. A method may be used in which a shape or a large number of small holes are blown out toward the plasma space from a blowout port arranged in a line.

Further, the side surface of the plasma space formed between the roll electrode and the curved electrode (side surface in the rotation direction of the roll electrode)
Is preferably used because the mixed gas is efficiently consumed.

In the discharge plasma processing apparatus embodying the present invention, the base material is brought into close contact with the roll electrode, and the roll electrode is rotated in accordance with the transport speed of the base material to introduce the base material into the plasma space, and the gas inlet is provided. In a mixed gas atmosphere introduced from
By generating a discharge plasma by applying a voltage (electric field) between the roll electrode and the curved electrode, an inorganic thin film or the like can be continuously formed on the base material.

The electric field applied between the roll electrode and the curved electrode is not particularly limited as long as it can generate discharge plasma uniformly, but is preferably a pulsed electric field. . In other words, under a pressure near the atmospheric pressure, except for a gas component that takes a long time from the plasma discharge state to the arc discharge state, the plasma discharge state is not stably maintained, and the state immediately shifts to the arc discharge state. By applying the applied electric field, the discharge between the electrodes can be stopped before the transition from the glow discharge to the arc discharge, and by forming such a periodic pulsed electric field between the opposing electrodes, As a result, pulsed glow discharge is repeatedly generated, and as a result, discharge plasma can be generated for a long time in a stable glow discharge state.

The pulse voltage waveform is not particularly limited, and examples thereof include an impulse type and a modulation type. A pulse of a type in which a voltage is applied to either the positive or negative polarity side may be used. Good. The shorter the rise time of the pulse, the more efficiently the gas is ionized during the generation of plasma. Since the rise time of the pulse is determined by the power supply used, it is preferable to select a power supply that makes the rise time as short as possible.

Further, modulation may be performed using pulses having different voltage waveforms, rise times, and frequencies. Such modulation is effective in performing high-speed continuous surface treatment. A higher pulse frequency and a shorter pulse width are suitable for high-speed continuous surface treatment.

The magnitude of the pulse voltage is determined as appropriate, but is preferably in a range where the electric field intensity is 1 to 40 kV / cm when applied to the counter electrode. If it is less than 1 kV / cm, it takes too much time for the treatment, and if it exceeds 40 kV / cm, an arc discharge occurs. Note that a direct current may be superimposed on the electric field applied to the counter electrode.

Then, a plurality of sets of counter electrodes (roll electrodes and curved electrodes) having the above-described structure are arranged adjacent to each other, and the base material is placed in a state where the base material is in close contact with one of the facing surfaces of the counter electrodes. By continuously supplying and passing through the plasma space of each counter electrode, thin films of the same type or different types can be successively formed for each set.

In this case, the area in which each set of the counter electrodes is accommodated constitutes an independent small-unit discharge plasma processing apparatus, and the processing gas is applied to each apparatus so that the processing gas has a pressure near the atmospheric pressure. Supplied. Further, the base material is made to continuously travel in the space between the counter electrodes by a known method, and is successively introduced into the next small unit of the discharge plasma processing apparatus.

Further, it is preferable that a solid dielectric is provided on at least one of the opposed surfaces of each of the opposed electrodes of the discharge plasma processing apparatus in small units. However, the arrangement of the solid dielectric does not need to be the same for all the counter electrodes of the discharge plasma processing apparatus for each small unit.

Next, the configuration of an in-line film thickness measurement system applied to the continuous film formation method using normal pressure plasma of the present invention will be described with reference to the conceptual diagram of FIG.

The in-line film thickness measuring system 1 shown in FIG. 2 includes a light source 2 for irradiating light on the formed substrate S, a spectroscope 3 for dispersing light reflected by the substrate S, and Optical multi-channel analyzer 4 to detect (hereinafter referred to as OMA4)
And a microcomputer 5 for calculating the thickness of the thin film based on the output of the OMA 4.

The light source 2 used in the in-line film thickness measuring system 1 is 200
It is preferable to cover the wavelength range of ８００800 nm, particularly the wavelength range of 220 to 780 nm. Such a wavelength range is selected depending on the purpose, but generally ranges from 10 to 200 nm. If the thickness is 40 nm or more, only visible light is sufficient. However, measuring a film thickness of less than 40 nm requires light in the ultraviolet region of 200 to 380 nm.

It is difficult to cover such a wavelength range with one type of light source, and actually, it is necessary to use two types of light sources. Examples of the two types of light sources include a halogen lamp and a deuterium lamp.

Light from these light sources has a diffusive property unlike laser light, so that light is irradiated from the light source to the sample (substrate on which the film is formed), and reflected light from the sample is transmitted to the spectroscope. It is preferable to use an optical fiber for transmission.

Since the wavelength range of the light used for the measurement is in the ultraviolet to visible range, it is preferable to use non-fluorescent and low-loss quartz as the core of the optical fiber. Further, in order to increase the amount of transmitted light in order to increase the sensitivity, it is preferable to use a bundle of elementary fibers.

In the in-line film thickness measurement system of FIG. 2, it is preferable to use specular reflection in order to pick up reflected light from the sample, and the incident angle is preferably within 10 degrees. Further, the distance between the sample and the optical fiber is preferably 2 mm or less. Under these conditions,
Since it is physically impossible to arrange two optical fibers for incidence and reflection, it is preferable to use a Y-shaped optical fiber by fusing the two fibers and to vertically enter the sample. . In addition, by using a multi-branch fiber obtained by expanding a Y-shaped fiber and a fiber switching device, measurement at multiple points becomes possible, and the spatial distribution of the film thickness can be obtained.

In the in-line film thickness measurement system shown in FIG.
Is to separate the reflected light from the base material into spectral components, for example, a diffraction grating is used. The light split by the spectroscope 3 is detected by the OMA 4.

The OMA 4 includes a one-dimensional or two-dimensional image sensor (CCD) 4a, a readout circuit 4b, and a signal processing circuit 4c.
And outputs the spectrum data of the light from the spectroscope 3 to the microcomputer 5.

The microcomputer 5 can calculate the reflection characteristics of the multilayer film in consideration of the reflection on the back surface of the base material and the wavelength dispersion of the optical constants (refractive index and absorption coefficient) of each layer as software for calculating the film thickness, and Software having a curve fitting function is set. With this software, the optical constant and thickness of each layer below the thin film to be deposited and the optical constant of the thin film layer to be deposited are input and fixed in advance, so that a single layer In addition, it is possible to calculate the thickness of the multilayer film having a plurality of layers.

Here, in the above-described in-line film thickness measurement system, when the distance between the substrate and the optical fiber changes due to the running of the substrate, the signal level of the reflected light changes and adversely affects the film thickness measurement. The installation location of the optical fiber is preferably within 2 mm on a traveling roll or when the substrate and the roll are separated. When an optical fiber is installed on a traveling roll, if the roll surface is a mirror surface, the reflected light on the roll surface will be added as noise and accurate film thickness measurement values will not be obtained. Need to be coarse.

In the continuous film forming method using normal pressure plasma of the present invention, the thin film is formed based on the difference between the film thickness (actually measured value) measured by the above-described in-line film thickness measuring system and the set film thickness. By applying feedback control to the generation control system, the film thickness can be kept uniform. Note that a general system can be used for such feedback control. The control factor is preferably a power supply voltage for plasma discharge, a frequency, or a flow rate of a mixed gas. However, when controlling the voltage, care must be taken because if the voltage is too low, discharge does not occur, and if the voltage is too high, arc discharge occurs and the electrode is damaged.

[0057]

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a diagram schematically showing a configuration of a film forming apparatus for performing a continuous film forming method using normal-pressure plasma according to the present invention.

The film forming apparatus shown in FIG. 3 mainly includes high-voltage pulse power supplies 110 and 111 and discharge plasma processing apparatuses 120 and 12.
1, an unwinding roll 180, a take-up roll 181 and the like.

The discharge plasma processing apparatuses 120 and 121 respectively include counter electrodes including roll electrodes 130 and 131 and curved electrodes 140 and 141, processing gas supply units 150 and 151,
There are provided seal mechanisms 152, 153 and 154, 155, and processing gas discharge sections 170, 171. Processing gas supply units 190 and 191 are connected to the processing gas supply units 150 and 151, respectively. In addition, each of the processing gas discharge units 170 and 171 has an exhaust pump P1.
, P2 are connected. Note that each curved electrode 140,
The surface of 141 is covered with solid dielectrics 160 and 161.

Heating / cooling devices 182 and 183 are provided adjacent to the discharge plasma processing devices 120 and 121, respectively, so that the substrate S can be maintained at a temperature suitable for film formation. The discharge plasma processing apparatuses 120 and 121 are sealed by seal mechanisms 152, 153 and 154 and 155 and further sealed by a seal mechanism (not shown), and are reduced to a substantially vacuum state by vacuum pumps P10 and P20. .

The discharge plasma processing apparatus 12 having such a configuration
At 0 and 121, the vacuum pumps P10 and P20 are used to reduce the pressure in the discharge plasma processing apparatuses 120 and 121 (inside the processing vessel) to a substantially vacuum state, and then, between the roll electrodes 130 and 131 and the curved electrodes 140 and 141 ( The processing gas is blown out from the processing gas supply units 150 and 151 into the discharge space, and the processing gas is exhausted by the processing gas discharge units 170 and 171 and the exhaust pumps P1 and P2. The roll electrodes 130 and 131 and the curved electrodes 140 and 14 are introduced at a pressure near atmospheric pressure and at a constant flow rate.
By applying a pulsed electric field from the high-voltage pulse power supply units 110 and 111 between the electrodes 1 and 2, discharge plasma corresponding to the type of the processing gas can be generated between the opposed electrodes, and the generated plasma can be generated. Accordingly, a thin film can be formed on the base material S traveling along the roll electrodes 130 and 131.

In the film forming apparatus shown in FIG. 3, separate high-voltage pulse power sources 1
Although 10 and 111 are provided, a common high voltage pulse power supply may be used as long as the conditions for generating discharge plasma can be satisfied in the continuous film forming method of the present invention.

In FIG. 3, the discharge plasma processing apparatuses 120 and 12
Although the example in which only the inside of 1 is decompressed and replaced with the processing gas is shown, all of the unwinding roll 180, the take-up roll 181, and the heating / cooling devices 182 and 183 are depressurized and replaced with the processing gas. Is also good.

Here, in the discharge plasma processing apparatuses 120 and 121 described above, the processing gas introduced into the discharge space of each counter electrode from the processing gas supply units 150 and 151 forms a laminar flow on the substrate S. However, the flow velocity is required to be substantially uniform in the width direction (processing width) of the substrate S. FIG. 4 shows an example of the processing gas supply unit satisfying such conditions. FIG. 4A is a cross-sectional view of the processing gas supply unit, and FIG.
(B) is an AA cross-sectional view of FIG.

The processing gas supply unit shown in FIG. 4 is provided with a gas inlet 56 to which a gas supply pipe G is connected at one longitudinal end of a rectangular processing gas supply unit 50 and two chambers. 5
7 and 58, and the first chamber 57 is provided with the swash plate 14 on a diagonal line of the first chamber 57 so as to face the gas introduction direction, thereby forming a section that becomes narrower as the distance from the gas introduction port 56 increases. The processing gas introduced from the gas inlet 56 was turbulent, the density in the section was made substantially uniform, the flow velocity was made substantially uniform, and the direction of the processing gas was deflected. Thereafter, the gas is rectified from a large number of uniform small hole groups 15 provided near the edge of the first chamber 57 and blown out to the second chamber 58. In the second chamber 58, a partition plate 24 having a uniform gap 23 at one end is arranged, and a slit 25 having a uniform width is formed near the edge. The gas coming out of the group 15 is the partition 2
4 and flows out from the slit 25 into the discharge space as a laminar flow.

A point to be noted in this embodiment is that the in-line film thickness measuring system 1 is installed at the terminal end of the film forming apparatus shown in FIG.

The in-line film thickness measuring system 1 includes a light source 2, a spectroscope 3,
An MA 4, a microcomputer 5 and a Y-shaped optical fiber 6 are provided.

The tip of the Y-shaped optical fiber 6 is located in front of a roll 156 disposed downstream of the outlet seal 155 of the discharge plasma processing apparatus 121 (for example, at a position of 1.5 mm immediately before the base material S comes into contact with the roll 156). The light emitting surface 6a is opposed to the base material S at an interval (for example, 1 mm). One branch fiber 6 of the Y-shaped optical fiber 6
The light source 2 is connected to 1, and the spectroscope 3 is connected to the other branch fiber 62.

The light source 2 includes, for example, a deuterium lamp and a halogen lamp, and outputs light having a wavelength of 220 to 800 nm. The spectroscope 3 is, for example, a spectroscope using a blazed holographic concave diffraction grating.

The OMA 4 is composed of, for example, a one-dimensional area image sensor using a CCD, a readout circuit, a signal processing circuit, an AD converter, and the like (see FIG. 2), and outputs spectrum data of detected light.

In the in-line film thickness measuring system 1 having the above configuration, the light from the light source 2 is applied to the thin film forming surface of the base material S through the Y-shaped optical fiber 6, and the light reflected by the base material S is converted to Y light. An optical system is formed through which the light separated by the spectroscope 3 is incident on the OMA 4 through the U-shaped optical fiber 6, and the output signal of the OMA 4, that is, the reflected light from the base material S forms the spectroscope 3. Is input to the microcomputer 5.

The microcomputer 5 can calculate the reflection characteristics of the multilayer film in consideration of the reflection on the back surface of the base material and the wavelength dispersion of the optical constants (refractive index and absorption coefficient) of each layer as software for calculating the film thickness. Software having a curve fitting function is set. With this software, the optical constant and thickness of each layer below the thin film to be deposited and the optical constant of the thin film layer to be deposited are input and fixed in advance, so that a single layer In addition, it is possible to calculate the thickness of the multilayer film having a plurality of layers.

The present embodiment is characterized in that the film thickness data calculated by the microcomputer 5 is fed back to the film formation generation control system 7 to control the film thickness of the thin film formed on the substrate S. .

Specifically, the film formation control system 7 calculates a difference between the film thickness data calculated by the microcomputer 5 and a preset film thickness set value, and sets the difference to 0. To
The thickness of the thin film formed on the base material S is kept constant by performing feedback control of controlling the oscillation frequency or voltage of the high voltage pulse power supply units 110 and 111.

The control factors used for such feedback control include the above-described power supply voltage and frequency for plasma discharge, and various conditions of the processing gas supply system such as the flow rate of the processing gas. Is mentioned. Further, the film thickness control may be performed by using the plasma discharge conditions in which all of them are combined as a control factor.

[0077]

【Example】

First, in the film forming apparatus shown in FIG. 3, the roll electrodes 130, 1 arranged in the discharge plasma processing apparatuses 120, 121 are used.
31 was used having a size of 810 mm in width × 400 mm in diameter and coated with aluminum oxide having a thickness of 15 mm as a solid dielectric on the electrode facing surface by a thermal spraying method. Each of the curved electrodes 140 and 141 has a projected area of 810 mm in width × 100 mm in length and a radius of curvature of 202 mm, and has a wall thickness of 15 m as a solid dielectric on the electrode facing surface.
m was coated with aluminum oxide by thermal spraying.

As the processing gas supply units 150 and 151 and the processing gas discharge units 170 and 171, those having the gas blowing slits 25 shown in FIG. 4 were used.

The high-voltage pulse power supplies 110 and 111 are manufactured by Heiden Laboratories (semiconductor element: IXYS, model number IXBH40N).
160-627G), and the roll electrode 13
A pulse electric field having a pulse voltage waveform shown in FIG. 5 and a rise time of 5 μs and a pulse width of 70 μs was applied between 0 and 131 and the curved electrodes 140 and 141.

Then, the substrate S is caused to run while applying a tensile stress of 9.8 N / m ² by the unwinding roll 180 and the winding roll 181, and the discharge plasma processing apparatuses 120,
After introducing into the discharge plasma processing apparatus 120 and 121 to about 133 Pa with the vacuum pumps P10 and P20, the pressure is returned to the atmospheric pressure with the carrier gas, and the processing gas excited by the discharge plasma under the processing conditions of each embodiment. Was brought into contact with the surface of the substrate S to form a thin film on the substrate S.

On the other hand, in the in-line film thickness measuring system 1 shown in FIG. 3, the light source 2 used was MC-2530 manufactured by Otsuka Electronics Co., Ltd. The light source 2 includes a deuterium lamp and a halogen lamp, and has a spectral distribution in a wavelength range of 220 to 800 nm.

The Y-shaped optical fiber 8 was manufactured by Otsuka Electronics Co., Ltd. (no model number). This Y-shaped optical fiber is φ25
It is a bundle of 0 μm quartz elementary fiber. One of the branched Y-shaped optical fibers is used as a light source 2.
The other end is connected to the spectroscope 3, and the fused fiber end is placed at a position of 1.5 mm immediately before the base material S coming out of the outlet seal 155 of the discharge plasma processing apparatus 121 comes into contact with the roll 156. It was installed at an interval of 1 mm from the surface.

For spectroscopic / measurement of the reflected light from the substrate S, the spectroscope 3 and the O
Apparatus incorporating both MA4: Otsuka Electronics Co., Ltd., MC
PD-7000 was used. This apparatus includes a spectroscope using a blazed holographic concave diffraction grating and an OMA using a one-dimensional area image sensor using a CCD, and has a wavelength accuracy of 1 nm for measurement.

Then, the output of the MCPD-7000 was processed by a microcomputer 5 (software manufactured by Otsuka Electronics Co., Ltd., no model number) via an interface, thereby obtaining a reflectance spectrum of the substrate S on which the film was formed. However, the measurement conditions were one minute intervals, and one measurement was performed ten times with a sampling time of 20 ms. Example 1 In the film forming apparatus shown in FIG.
A 5 μm PET (OLF175, manufactured by Teijin Limited) substrate was brought into close contact with the roll electrode 130, and the substrate was run at a running speed of 0.5 / min. 1 cc / min of tetraisopropoxytitanate as a raw material and 60 SLM of argon as a carrier gas are introduced into a discharge plasma processing apparatus 120, and a pulse voltage of a repetition frequency of 4 kHz and a voltage of 2 kVp-p is applied to cause a plasma discharge to be performed on a PET substrate. TiO2 was deposited. At this time, the TiO2 film thickness was measured by the in-line film thickness measuring system 1. FIG. 6 shows the measurement results. <Example 2> In the film forming apparatus shown in FIG. 3, the same PET substrate as in Example 1 was brought into close contact with the roll electrode 131, and the traveling speed was 0.5 m /
The substrate was run in minutes. Discharge plasma processing apparatus 121
Then, 1 cc / min of tetraethoxysilane as a raw material, 34 SLM of argon, 8 SLM of nitrogen, and 8 SLM of oxygen are introduced as a carrier gas, and a repetition frequency of 4 kHz and a voltage of 6
A pulse voltage of 5 Vp-p is applied to cause a plasma discharge and P
SiO2 was formed on the ET substrate. At this time, the measurement film thickness value obtained by the in-line film thickness measurement system 1 is input, and the microcomputer (software made by Otsuka Electronics Co., Ltd .: no model number) on the film formation control system 7 side oscillates the high-voltage pulse power supply 111. The frequency was fed back to control the thickness of the SiO2 film to 130 nm. FIG. 7 shows the results. As is clear from FIG. 7, the thickness of the thin film formed on the PET base material is equal to the set value ±
It can be seen that it is within 2 nm. <Comparative Example 1> The center part in the width direction of the base material formed in Example 1 was cut out at intervals of 50 cm in 5 cm squares in the flow direction, and the back surface was # 40.
0 with sandpaper and black magic with diameter 2
It was painted to a size of about cm. The reflectance spectrum of this back-treated sample at a wavelength of 200 to 800 nm was measured with a spectrophotometer (manufactured by Hitachi, Ltd .: Model “U-3000”), and the reflectance spectrum was measured by optical property calculation software (JA Woollam). Manufactured by: WASEfo
r Windows) to calculate the TiO2 film thickness. FIG. 6 shows the calculation results. From FIG. 6, it can be seen that the measurement result (Example 1) by the in-line film thickness measurement system 1 steadily captures the fluctuation immediately after the start of the raw material supply. <Comparative Example 2> SiO2 was laminated on a PET substrate in the same manner as in Example 2 except that feedback control was not performed. FIG. 7 shows the SiO2 film thickness distribution in the flow direction of the substrate in that case. From the results of FIG. 7, when the feedback control is not performed, the mixed gas flow rate decreases,
Due to factors such as SiO2 adhering to the curved electrode,
It can be seen that the thickness of the SiO2 film formed on the PET substrate has decreased.

[0085]

【The invention's effect】

As described above, according to the continuous film forming method using normal pressure plasma of the present invention, the thickness of a thin film formed on a substrate can be measured nondestructively and in-line. Further, since the fluctuation of the film thickness can be measured, the film thickness can be kept constant by performing the feedback control based on the measured value of the film thickness. As a result, on a continuously supplied substrate, various thin films such as an anti-reflection film, a high-reflection film, or an optical thin film requiring high accuracy such as a filter are formed with high film thickness accuracy and stably. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a conventional discharge plasma processing apparatus.

FIG. 2 is a conceptual diagram of an in-line film thickness measurement system.

FIG. 3 is an explanatory view showing an example of an apparatus for performing a continuous film forming method using normal pressure plasma of the present invention.

FIG. 4 is a cross-sectional view illustrating a configuration of a processing gas supply unit applied to the embodiment of the present invention.

FIG. 5 is a waveform diagram of a pulse voltage applied between opposed electrodes of the discharge plasma processing apparatus.

FIG. 6 is a graph showing both the film thickness measurement result of Example 1 and the film thickness calculation result of Comparative Example 1.

FIG. 7 is a graph showing the thickness measurement results of Example 2 and Comparative Example 2 together.

[Explanation of symbols]

1 In-line film thickness measurement system 2 Light source 3 Spectroscope 4 Optical multi-channel analyzer (OM
A) 5 microcomputer 6 Y-shaped optical fiber 110, 111 high-voltage pulse power supply unit 120, 121 discharge plasma processing unit 130, 131 roll electrode 140, 141 curved surface electrode 150, 151 processing gas supply unit 160, 161 solid dielectric 170 , 171 Processing gas discharge unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA30 BB13 BB15 BB17 CC02 CC31 DD06 FF00 GG02 GG03 HH13 JJ02 JJ09 JJ25 LL02 LL42 LL67 NN20 PP16 QQ01 QQ03 QQ23 QQ25 QQ27 4F006 AA11 BA67A18 BA09A09 BA09A09 CA17 FA03 GA14 KA39 KA41 LA24

Claims (2)

[Claims] In a continuous film forming method for forming a thin film on a substrate by performing a discharge plasma treatment in a mixed gas atmosphere under a pressure near the atmospheric pressure, light is applied to the formed substrate. A light source, a spectroscope that splits the light reflected by the substrate, an optical multi-channel analyzer that detects the split light, and a computer that calculates the thickness of the thin film based on the output of the analyzer. Provided,
A continuous film forming method using normal pressure plasma, wherein the film thickness of a thin film formed on a substrate is measured in-line. 2. The film thickness is controlled by feeding back a difference between a film thickness of a thin film calculated by a computer and a preset film thickness to a thin film generation control system. 2. A continuous film forming method using the normal pressure plasma according to 1.