JP6776212B2 - Manufacturing method of optical film - Google Patents

Description

The present invention relates to a process for the production of optical science film that form a thin film by sputtering.

Conventionally, a base film is run while being wound around a can roll, and a thin film is formed on the surface of the base film by sputtering (see, for example, Patent Documents 1 and 2). For example, when producing an antireflection film, a plurality of low-refractive materials such as SiO ₂ , MgF and high-refractive materials such as Nb ₂ O ₅ and TiO ₂ are formed, and the entire thickness of each layer is adjusted. The optical film is continuously formed on the base film so as to have a thin film structure optically designed in advance.

Japanese Unexamined Patent Publication No. 2000-080185 JP-A-2007-224322

However, with the increase in the width of the base film in recent years, it has become difficult to keep the film thickness error in the width direction within an allowable range in the film formation of each layer.

The present invention has such a proposed in view of the conventional circumstances, to provide a manufacturing method of an optical science film that can be formed a thin film of uniform thickness in the width direction.

In order to achieve the above-mentioned object, the method for producing an optical film according to the present invention is a method for producing an optical film containing a multi-layered thin film using a thin film forming apparatus, and the thin film forming apparatus is a method for producing an optical film. , An unwinding portion that unwinds the base film in the longitudinal direction, a film forming chamber unit in which a plurality of film forming portions are arranged in the longitudinal direction of the base film, and a group in which a thin film is formed by the film forming chamber unit. The thin film formed on the base film by being provided after the winding portion for winding the material film and at least one of the film forming chamber units, and the base film is continuously supplied in the longitudinal direction. A measuring unit that measures the spectrum of reflection characteristics among the optical characteristics in the width direction of the above, a supply unit that is provided with a plurality of gas nozzles in the width direction of the base film and supplies reactive gas in the vicinity of the target, and the measuring unit. The measurement unit includes a control unit that controls the flow rate of the reactive gas ejected from the plurality of gas nozzles based on the reflection characteristic in the width direction in the above, and the measurement unit includes the thin film on the base film. light is irradiated from an oblique direction Te and the light projecting unit, with an optical head having a light receiving portion for receiving reflected light from an oblique direction from the thin film on the base film is provided, wherein the optical film, wherein When a polarizing film is formed between the base film and the thin film, the reflected light of only the thin film is measured, and there is a difference between the spectrum measured by the measuring unit and the desired spectrum, the said It is characterized in that the flow rate of the reactive gas supplied to any of the thin film portions is adjusted so that the deviation of the wavelength corresponding to the difference is within a desired range.

According to the present invention, in order to control the flow rate of the reaction gas from each gas nozzle provided in the width direction based on the optical characteristics in the width direction of the thin film formed on the base film, the thickness is uniform in the width direction. Thin film can be formed.

It is a perspective view which shows the outline of the thin film forming apparatus which concerns on one Embodiment of this invention. It is a figure which shows the optical measurement system. It is a figure which shows an example of an optical head. It is a figure which shows another example of an optical head. It is sectional drawing which shows the outline of a sputtering chamber. It is a perspective view of the protection plate. It is an exploded perspective view of a gas nozzle. It is a figure which shows the control system which controls the flow rate of a gas in a sputtering chamber. It is a flowchart which shows the manufacturing method of the optical film which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure of the antireflection film in an Example. It is a graph which shows the peak wavelength in the width direction of the 5th layer SiO ₂ single layer. It is a graph which shows the relationship between the film thickness of the 2nd layer and the reflection spectrum. It is a graph which shows the relationship between the film thickness of the 2nd layer and a hue. It is a graph which shows the relationship between the film thickness of the 2nd layer and the Y value. It is a graph which shows the relationship between the film thickness of the 3rd layer and the reflection spectrum. It is a graph which shows the relationship between the film thickness of the 3rd layer, and the hue. It is a graph which shows the relationship between the film thickness of the 3rd layer, and the Y value. It is a graph which shows the relationship between the film thickness of the 4th layer and the reflection spectrum. It is a graph which shows the relationship between the film thickness of the 4th layer and a hue. It is a graph which shows the relationship between the film thickness of the 4th layer, and the Y value. It is a graph which shows the relationship between the film thickness of the 5th layer and the reflection spectrum. It is a graph which shows the relationship between the film thickness of the 5th layer and a hue. It is a graph which shows the relationship between the film thickness of the 5th layer, and the Y value.

Hereinafter, embodiments of the present invention will be described in detail in the following order with reference to the drawings.
1. 1. Thin film forming device 1.1 Overall overview of thin film forming device 1.2 Optical property measurement unit 1.3 Sputter chamber 1.4 Reactive gas supply unit 1.5 Sputter chamber control 2. Thin film forming method 3. Manufacturing method of optical film 4. Example

<1. Thin film forming device>
The thin film forming apparatus according to the embodiment of the present invention includes a measuring unit in which a base film is continuously supplied in the longitudinal direction and measures the optical characteristics in the width direction of the thin film formed on the base film, and a base material. A plurality of gas nozzles are provided in the width direction of the film, and the flow rate of the reactive gas ejected from each gas nozzle is controlled based on the optical characteristics in the width direction of the supply unit that supplies the reactive gas near the target and the measurement unit. It is equipped with a control unit and can form a thin film having a uniform thickness in the longitudinal direction and the width direction.

Further, as a specific configuration, a film forming section having a supply section, a sputtering electrode for applying a voltage to the target, and a plasma measuring section for measuring the emission spectrum of plasma in the width direction of the base film during film forming is provided. It is preferable to prepare. As a result, the control unit can control the flow rate of the reactive gas ejected from each gas nozzle and the voltage applied to the target based on the optical characteristics in the width direction of the measurement unit and the emission spectrum of the plasma measurement unit. It is possible to form a thin film having a uniform thickness depending on the direction.

Further, as a specific configuration, a thin film is formed by an unwinding portion for unwinding the base film in the longitudinal direction, a film forming unit in which a plurality of film forming portions are arranged in the longitudinal direction of the base film, and a film forming unit. It is preferable to provide a winding portion for winding the formed base film. As a result, a multi-layered thin film can be formed from unwinding to winding of the base film. Further, the measuring unit is preferably installed after the film forming unit, but is preferably installed at least after the last film forming unit, that is, between the film forming unit and the winding unit. Thereby, the optical characteristics of both the single-layer thin film and the multi-layer thin film can be measured.

Hereinafter, the specific configuration of the thin film forming apparatus will be described in detail. In the thin film forming apparatus shown as a specific example, a base film, which is a base film, is run while being wound around a can roll, and a thin film is formed on the surface of the base film by sputtering.

<1.1 Overview of thin film forming equipment>
FIG. 1 is a perspective view showing an outline of a thin film forming apparatus according to an embodiment of the present invention. This thin film forming apparatus supplies the base film 1 from the unwinding roll 11 which is the unwinding portion, and winds the base film 1 on which the thin film is formed by the winding roll 12 which is the winding portion. Further, a first film forming chamber unit and a second film forming chamber unit, which are film forming units, are provided in the vacuum chamber. The vacuum chamber is connected to a vacuum pump that discharges air and can be adjusted to a predetermined degree of vacuum.

The first film forming chamber unit and the second film forming chamber unit are provided with a first can roll 21 and a second can roll 22, respectively, and are formed so as to face the outer peripheral surfaces of the can rolls 21 and 22. A plurality of sputtering chambers SP1 to SP1 to 10 are fixed. As will be described later, each of the sputtering chambers SP1 to 10 is provided with a predetermined target mounted on the electrode and a supply unit having a plurality of gas nozzles in the width direction of the base film 1.

Further, the thin film forming apparatus includes an optical monitor 31 which is a measuring unit for measuring optical characteristics between the first film forming chamber unit and the second film forming chamber unit, that is, after the film is formed by the sputtering chamber SP5. As a result, it is possible to control the film formation of the intermediate product after the first film formation chamber unit, and it is possible to reduce the adjustment time at the time of adjustment by the single layer, which will be described later. Further, an optical monitor 32, which is a measuring unit for measuring optical characteristics after the second film forming chamber unit, that is, after forming a film in the sputtering chamber SP10, is provided. Thereby, the quality of film formation of the final product after the second film formation chamber unit can be confirmed.

As will be described later, the optical monitors 31 and 32 measure the optical characteristics of the thin film formed on the base film 1 in the width direction by an optical head capable of scanning in the width direction. The optical thickness distribution in the width direction can be obtained by measuring the peak wavelength of the reflectance as an optical characteristic with the optical monitors 31 and 32 and converting it into an optical thickness.

A thin film forming apparatus having such a structure unwinds the base film 1 from the unwinding roll 11, forms a thin film on the base film 1 when the first can roll 21 and the second can roll 22 are conveyed, and winds the base film 1. By winding with a roll 12, a multi-layered thin film can be obtained. Here, the optical characteristics of the thin film formed on the base film 1 in the width direction are measured by the optical monitors 31 and 32, and the flow rate of the reactive gas from each gas nozzle provided in the width direction is based on the optical characteristics. By controlling the above, it is possible to form a thin film having a uniform thickness in the longitudinal direction and the width direction.

<1.2 Optical characteristics measurement unit>
Next, an optical measurement system for measuring optical characteristics with optical monitors 31 and 32 will be described. FIG. 2 is a diagram showing an optical measurement system. The optical measurement system includes an optical measurement unit 33 having an optical head 331, a drive unit 34 for moving the optical head 331 in the width direction of the base film, a light source 35 for supplying light to the optical head 331, and light reception by the optical head 331. It includes a spectroscope 36 that measures the spectrum of the light, and a measurement control unit 37 that outputs a measurement result of a desired spectrum.

The optical measurement unit 33 transmits light through an optical head 331 having a light projecting unit that irradiates a thin film on the base film with light and a light receiving unit that receives light reflected from the thin film on the base film, and a base film. It is provided with a measuring roll 335 having a light absorbing surface that absorbs the light. By moving the optical head 331 in the width direction of the base film, the reflection characteristics such as reflectance, reflection hue, peak wavelength and bottom wavelength of the reflection spectrum can be measured in the width direction of the thin film formed on the base film. Can be done.

As a specific configuration, the cam follower 332 is attached to the optical head 331 so as to mesh and travel in the cam groove of the traverse cam 333. The traverse cam 333 is connected to the drive unit 34, and a spiral or inverted spiral cam groove is formed on the surface in the longitudinal direction. Further, a guide rail 334 is provided in order to ensure stable running of the cam follower 332. Then, the cam follower 332 reciprocates on the traverse cam 333 due to the rotary motion or the unidirectional rotary motion in which the traverse cam 333 reverses at regular intervals, and the optical head 331 attached to the cam slave 332 moves to the guide rail 334. Reciprocate along. Further, the measurement roll 335 is a so-called black roll having low surface reflection, and absorbs the light transmitted through the base film.

The drive unit 34 is connected to the measurement control unit 37, and moves the optical head 331 to a predetermined position in the width direction of the base film by a command from the measurement control unit 37. The light source 35 guides light to the optical head 331 via an optical fiber. Further, the spectroscope 36 receives light from the optical head 331 via an optical fiber and measures a spectrum or the like. The measurement control unit 37 performs arithmetic processing on the spectrum and the like in the spectroscope 36, and outputs reflection characteristics such as reflectance, reflected hue, and peak wavelength and bottom wavelength of the reflection spectrum. Further, the optical head 331 is moved to a predetermined position in the width direction of the base film to obtain a reflection characteristic at the predetermined position. For example, by measuring 25 points at intervals of 50 mm in the width direction, the reflection characteristics of the base film having a width of 1300 mm can be measured in the width direction.

FIG. 3 is a diagram showing an example of an optical head. This optical head is a coaxial optical system 38 in which a light emitting unit and a light receiving unit are arranged coaxially. This coaxial optical system 38 is effective for a single-layer base material in which an AR (Anti-Reflection) film is formed on a transparent base material such as PET (polyethylene terephthalate) and TAC (Tri Acetyl Cellulose).

Further, FIG. 4 is a diagram showing another example of the optical head. This optical head is a biaxial optical system having a light projecting unit 39 that irradiates a thin film on a base film with light from an oblique direction and a light receiving unit 40 that receives reflected light of light emitted from an oblique direction. is there. Further, the optical head of the biaxial optical system arranges a polarizing plate 39a that polarizes the light emitted from the light projecting unit 39. Thereby, only the AR film characteristics on the polarizing film can be measured with respect to the multilayer base material in which the polarizing film and the AR film are formed in this order on the transparent substrate.

<1.3 Sputter chamber>
Next, a sputtering chamber fixed so as to face the outer peripheral surfaces of the can rolls 21 and 22 will be described. As the sputtering method used in the sputtering chamber, a magnetron sputtering method, a two-pole sputtering method that only uses plasma generated by DC glow discharge or high frequency, a three-pole sputtering method that adds a hot cathode, and the like can be used.

In the present embodiment, it is preferable to use the magnetron sputtering method from the viewpoint of increasing the film forming speed. In the magnetron sputtering method, the magnetic field confine the plasma and increase the path length of the electrons moving under the influence of the electric field, thereby increasing the probability of gas atom-electron collision and generating high-density plasma near the target. It is possible to increase the film speed.

FIG. 5 is a cross-sectional view showing an outline of the sputtering chamber. A pair of targets 41a and 41b can be installed in this sputtering chamber, and magnetic field generation sources 42a and 42b that form a magnetic field on the target surface, sputtering electrodes 43a and 43b for applying to the target, and gas in the vicinity of the target are applied. The supply units 44a and 44b to be supplied and a protective plate 45 for preventing the film from being deposited on unnecessary portions are provided.

The targets 41a and 41b are appropriately selected depending on the composition of the thin film such as Si, Nb, Al, Ti, Mo, and ITO.

The magnetic field generation sources 42a and 42b are made of permanent magnets or electromagnets, and can utilize magnetron discharge in which the electric field and the magnetic field are orthogonal to each other. For example, a central magnet arranged on a substantially oval flat plate provided parallel to the sputter surface of the target on a center line extending in the longitudinal direction and an annular (endless) arrangement surrounding the central magnet. Peripheral magnets are installed with different polarities.

Each of the sputter electrodes 43a and 43b has a pair of cathodes / anodes arranged with a length substantially equal to the width of the base film. The known structure makes it possible to apply a negative DC voltage or a high frequency voltage to the target.

The supply units 44a and 44b are provided with a plurality of gas nozzles in the longitudinal direction of the target, that is, in the width direction of the base film, and introduce the reactive gas at a predetermined flow rate. The reactive gas is appropriately selected according to the composition of the thin film, and oxygen, nitrogen, carbon, hydrogen, a mixed gas thereof, or the like is used.

The adhesive plate 45 is arranged between the base film on the canroll and the target, and is substantially the same as a rectangle composed of, for example, the length in the width direction of the pair of targets 41a and 41b and the length in the width direction of the base film. Has a size window. The adhesive plate 45 is electrically floated from the anode / cathode, and the material thereof is not particularly limited as long as it has heat resistance.

FIG. 6 is a perspective view of the protective plate shown in FIG. As shown in FIG. 6, the protective plate 45 has openings 45a and 45b on the side surface in the width direction and the side surface in the longitudinal direction, and further has openings 45c on the outer upper surface of the window. By providing the opening in the adhesive plate 45, the exhaust area of the gas can be increased, and the controllability of the gas flow rate can be improved.

According to the sputtering chamber having such a configuration, since a pair of targets 41a and 41b can be installed in one film forming chamber, the film forming speed can be improved and a dense and stressful film can be formed. Can be done.

The method of applying a voltage for performing sputtering between the cathode and the anode is not particularly limited, and the method of applying an AC voltage between two targets is a voltage with a DC pulse power supply for one target. A so-called bipolar DMS method in which a voltage is alternately applied to two targets with a DC pulse power supply can be used. For example, when an AC voltage is applied to a pair of targets 41a and 41b, the targets 41a and 41b are alternately switched to the anode electrode and the cathode electrode, causing a glow discharge between the anode electrode and the cathode electrode to form a plasma atmosphere. Will be done. Here, the magnetic fields generated by the magnetic field generation sources 42a and 42b confine the plasma and increase the path length of the electrons moving under the influence of the electric field, thereby increasing the probability of gas atom-electron collision and near the target. High density plasma is generated. Then, the ions in the plasma atmosphere are accelerated toward one of the targets 41a and 41b that became the cathode electrode and impacted, and the target atoms are scattered, so that a thin film is formed on the surface of the base film.

<1.4 Reactive gas supply section>
Next, the supply units 44a and 44b provided with a plurality of gas nozzles in the longitudinal direction of the target, that is, the width direction of the base film in the sputtering chamber will be described.

FIG. 7 is an exploded perspective view of the gas nozzle. The gas nozzle 50 mixes the reactive gas and the carrier gas and ejects them. Specifically, a plurality of openings 50a, a gas pipe 51 for a reactive gas and a gas pipe 52 for a carrier gas are provided inside, and the reactive gas and the carrier gas are mixed in the mixing chamber 53, and a plurality of openings 50a are provided. The mixed gas is ejected from the opening 50a. A plurality of mixing chambers 53 are installed in the longitudinal direction of the target, that is, in the width direction of the base film, and the flow rate of the mixed gas can be controlled for each mixing chamber 53, that is, for each gas nozzle.

The gas pipe 51 for the reactive gas includes a connecting portion for introducing the gas and a pipe branched in a tournament shape so that the openings 51a of the pipe are evenly spaced from the connecting portion, and the gas is introduced via the mass flow controller 55. The gas is introduced from the connecting portion and the gas is uniformly discharged from the plurality of openings 51a via the pipes branched in a tournament shape. The structure of the gas pipe 52 of the carrier gas is not particularly limited, but is preferably the same as that of the reaction gas. In the mixing chamber 53, the reactive gas released from the plurality of openings 51a and the carrier gas released from the plurality of openings 52a of another pipe are mixed, and the mixed gas is uniformly ejected from the plurality of openings 50a.

According to the gas nozzle 50 having such a configuration, the gas can be ejected from the plurality of openings 51a and 52a of the gas pipes 51 and 52 at an equal flow rate, and the reactive gas and the carrier gas can be uniformly distributed in the mixing chamber 53. The mixed gas can be ejected from each opening 50a at an equal flow rate. Further, since the gas is introduced into the connecting portion of the gas pipe 51 via the mass flow controller, it is possible to control the flow rate of the gas from each gas nozzle installed in the longitudinal direction of the target, that is, in the width direction of the base film.

<1.5 Sputter chamber control>
FIG. 8 is a diagram showing a control system that controls the flow rate of gas in the sputtering chamber. This control system includes supply units 44a and 44b having a plurality of gas nozzles, a mass flow controller 55 that controls the mass flow rate of gas introduced into each gas nozzle, and a plasma emission monitor 56 that is a plasma measurement unit that measures the emission spectrum of plasma. And a controller 57 that controls the flow rate of gas in the mass flow controller 55 and the voltage applied to the sputter electrode.

As described above, the supply units 44a and 44b have a gas nozzle having a so-called tournament structure for ejecting gas at a uniform flow rate over the entire nozzle width, and the opening of the gas nozzle is equal to the longitudinal direction of the target, that is, the width direction of the base film. They are arranged so that they are spaced apart. The number of gas nozzles arranged in the width direction of the base film is preferably equal to or greater than the number of measurement windows for measuring the emission spectrum of plasma, which will be described later. Further, it is preferable to introduce the gas output from the same mass flow controller 55 into the gas nozzles located symmetrically with respect to the target.

The mass flow controller 55 measures the mass flow rate of the gas introduced into each gas nozzle and controls the flow rate. The reactive gas output from the mass flow controller 55 is introduced into the connecting portion of the gas pipe 51 and ejected at a uniform flow rate over the entire nozzle width of the gas nozzle.

The plasma emission monitor 56 measures the emission spectrum of plasma in the width direction of the base film during film formation. The sputter chamber is provided with a plurality of transparent measurement windows in the longitudinal direction of sputtering, that is, in the width direction of the base film, and light is introduced from these measurement windows at an intermediate position between the target and the base film facing the target to form a film. The spectral intensity of the emission spectrum of the plasma generated inside is measured.

The controller 57 controls the flow rate of the reactive gas ejected from each gas nozzle and the voltage applied to the target based on the optical characteristics in the width direction and the emission spectrum of the plasma in the width direction. For example using Si as a target, the _{O 2} is used as reactive gas, when forming the SiO _2, film thickness distribution based on the width direction of the optical properties of SiO _2, and the main spectral intensity of the SiO ₂ of the plasma emission Based on this, the flow rate of the O ₂ gas and the voltage applied to the Si target are controlled. Further, for example, when Nb is used as a target and O ₂ is used as a reactive gas to form Nb ₂ O ₅ , the film thickness distribution based on the optical characteristics in the width direction of Nb ₂ O ₅ and Nb _{2 of} plasma emission are obtained. The flow rate of the O ₂ gas and the voltage applied to the Nb target are controlled based on the intensity of the main spectrum of O ₅ .

A control system having such a configuration has a plurality of points for measuring the optical characteristics of the thin film and a point for measuring the emission spectrum of plasma in the width direction of the base film, and also has a plurality of points in the width direction of the base film as a means for correcting the film thickness. Since it has a plurality of gas nozzles capable of controlling the flow rate of the reactive gas, it is possible to form a thin film having a uniform thickness in the width direction.

<2. Thin film formation method>
Next, a thin film forming method using the above-mentioned thin film forming apparatus will be described.

The thin film forming method according to the embodiment of the present invention is a measuring step in which a base film is continuously supplied in the longitudinal direction and the optical characteristics in the width direction of the thin film formed on the base film are measured by a measuring device. It also has a film forming step of forming a thin film by controlling the flow rate of reactive gas ejected from each of a plurality of gas nozzles provided in the width direction of the base film based on the optical characteristics in the width direction of the measuring device. As a result, a thin film having a uniform thickness in the width direction can be formed.

Here, in the measurement step, the emission spectrum of the plasma in the width direction of the base film during film formation is measured, and in the film formation step, each gas nozzle is based on the optical characteristics in the width direction and the emission spectrum of the plasma in the width direction. It is preferable to control the flow rate of the reactive gas ejected from the target and the voltage applied to the target. This makes it possible to form a wide and long optical film with an error of ± 3% or less in the optical thickness in the width direction.

<3. Optical film manufacturing method>
Next, a method of manufacturing an optical film for manufacturing a multilayer optical film by using the above-mentioned thin film forming apparatus will be described.

FIG. 9 is a flowchart showing a method for manufacturing an optical film according to an embodiment of the present invention. In the method for producing an optical film according to an embodiment of the present invention, a base film is continuously supplied in the longitudinal direction at a first speed, a single thin film is formed for each layer, and the base film is formed in the width direction of the base film. An adjustment step S1 for adjusting the optical thickness distribution within a predetermined range, and an optical film forming step S2 for continuously supplying the base film in the longitudinal direction at a second speed faster than the first speed to form a multilayer thin film. And have.

The target film thickness (optical thickness) of each layer is obtained in advance by optical simulation. For example, when an antireflection film is formed on a polarizing plate, the first layer SiO _x is 5 nm, the second layer Nb ₂ O ₅ is 20 nm, the third layer SiO ₂ is 35 nm, and the fourth layer Nb ₂ O is formed. By setting ₅ to 35 nm and the SiO ₂ of the fifth layer to 100 nm, it can function as an antireflection film.

A specific method for forming an antireflection film composed of a multilayer thin film on a polarizing film by using the thin film forming apparatus described above is as follows.
(B) A step of energizing a predetermined sputtering chamber to form an arbitrary single-layer thin film of an antireflection film composed of multiple layers of thin films thicker than the target thickness on a base film for adjustment (b). Steps of measuring the reflection characteristics of a single-layer thin film and confirming that the peak value (or bottom value) of the reflection spectrum falls within a desired range (c) For any other layer, the above (a) (a) ( B) Repeating step (d) Step of energizing all the predetermined sputtering chambers used in (a) to (c) above to form an antireflection film composed of a multi-layered thin film on the base film for adjustment. (E) Step of measuring the reflection characteristics of the antireflection film and confirming that the peak value and hue of the reflection spectrum correspond to the desired range (f) If not applicable, the flow rate of gas in the corresponding sputtering chamber and sputtering. Step of adjusting voltage (g) Step of switching the base film for adjustment to a polarizing plate film and performing the main film formation

In steps (a) to (c), the film speed is reduced to increase the film thickness and the optical thickness distribution in the width direction is adjusted, so that the film speed in step (d) is faster than that in step (a). It is possible to make the optical thickness distribution in the width direction uniform when a multilayer antireflection film is formed.

Further, in the step (b), it is preferable to set the film speed so that the peak wavelength or the bottom wavelength of the reflection spectrum is in the range of 450 nm or more and 650 nm or less. Further, it is preferable to adjust the gas flow rate, sputtering voltage and the like so that the peak wavelength or the bottom wavelength of the reflection spectrum in the width direction of the single layer is within ± 15 nm for each layer. By adjusting the reflection characteristics in such a range, it is possible to form an antireflection film in which a desired spectrum can be uniformly obtained in the width direction of the base film.

<4. Example>
Hereinafter, examples of the present invention will be described. In this example, an antireflection film was formed on the polarizing plate as an optical film. The present invention is not limited to the following examples.

The thickness (optical thickness) of each layer of the antireflection film is determined by optical simulation, and the first layer SiO _x is 5 nm, the second layer Nb ₂ O ₅ is 20 nm, and the third layer SiO ₂ is 35 nm, 4 layers. The Nb ₂ O ₅ of the eye was set to 35 nm, and the SiO ₂ of the fifth layer was set to 100 nm.

FIG. 10 is a cross-sectional view showing the configuration of the antireflection film in the embodiment. In the thin film forming apparatus shown in FIG. 1, the antireflection film has a first layer of SiO _x as a sputtering chamber SP1, a second layer of Nb ₂ O ₅ as a sputtering chamber SP2, and a third layer of SiO ₂ as a sputtering chamber SP3. SP4, the fourth layer Nb ₂ O ₅ was formed in the sputtering chambers SP5, SP6, and the fifth layer SiO ₂ was formed in the sputtering chambers SP7 to SP10. A base film having a width of 1300 mm was used.

First, as shown in Table 1, the film speed of each layer was set to form a single-layer thin film thicker than the target thickness. Then, the reflection characteristics of the single-layer thin film are measured using the optical monitors 31 and 32, and the flow rate of the reactive gas until the peak value (or bottom value) of the reflection spectrum in the width direction falls within the range of a specific wavelength. And the voltage applied to the sputtering was adjusted.

FIG. 11 is a graph showing the peak wavelength in the width direction of the fifth layer of SiO ₂ single layer. This graph is obtained by measuring 25 peak wavelengths at equal intervals for a base film having a width of 1300 mm.

Next, all the sputtering chambers SP1 to SP10 were energized, the film speed was set to 1.8 m / min, and an antireflection layer composed of a plurality of layers was formed on the base film for adjustment. Then, the reflection characteristics of the antireflection film composed of a plurality of layers were measured using the optical monitors 31 and 32, and the peak value and hue of the reflection spectrum were adjusted so as to correspond to a desired range.

12 to 23 are graphs showing the correlation between the film thickness variation and the hue variation of each layer of the antireflection film by simulation. Here, FIGS. 12 to 14 are graphs showing the relationship between the film thickness and the reflection spectrum of the second layer, the relationship between the film thickness and the hue, and the relationship between the film thickness and the Y value, respectively. 15 to 17 are graphs showing the relationship between the film thickness and the reflection spectrum of the third layer, the relationship between the film thickness and the hue, and the relationship between the film thickness and the Y value, respectively. 18 to 20 are graphs showing the relationship between the film thickness and the reflection spectrum of the fourth layer, the relationship between the film thickness and the hue, and the relationship between the film thickness and the Y value, respectively. 21 to 23 are graphs showing the relationship between the film thickness and the reflection spectrum of the fifth layer, the relationship between the film thickness and the hue, and the relationship between the film thickness and the Y value, respectively.

After adjusting the sputtering chambers SP1 to SP10 based on the simulation results shown in FIGS. 12 to 23, the base film for adjustment was switched to a polarizing plate film to perform the main film formation. For example, when there is a difference between the spectrum of the present film formation and the desired spectrum at a predetermined position in the width direction, the discharge conditions are finely adjusted by utilizing the simulation results of FIGS. 12 to 23. Specifically, to adjust the reaction gas flow rate at a predetermined position of the cathode corresponding to a certain wavelength deviation between the best of the spectrum. For the adjustment of the reaction gas flow rate, the amount of increase or decrease was estimated with reference to the simulation, the spectrum of the changed result was confirmed on the optical monitor 32, and this adjustment was repeated until it approximated the spectrum of Best. As a result, the spectrum of the desired antireflection film could be obtained with a width of 1100 mm.

From the above, it was found that an optical film having a uniform thickness in the width direction can be formed by adjusting the peak wavelength of the reflection spectrum of each layer in the range of ± 15 nm in the width direction. Further, by adjusting the single-layer film and the multi-layer film described above, it is possible to start the main film formation with a desired spectrum within 2 hours.

1 base film, 11 unwinding roll, 12 unwinding roll, 21 1st can roll, 22 2nd can roll, 31 optical monitor, 32 optical monitor, 41 target, 42 magnetic field source, 43 sputter electrode, 44 supply Part, 45 protective plate, 50 gas nozzle, 51 gas tube for reactive gas, 52 gas tube for carrier gas, 55 mass flow controller, 56 plasma emission monitor, 57 controller

Claims (7)

A method for producing an optical film containing a multi-layered thin film using a thin film forming apparatus.
The thin film forming apparatus is
The unwinding part that unwinds the base film in the longitudinal direction,
A film forming chamber unit in which a plurality of film forming portions are arranged in the longitudinal direction of the base film, and
A winding unit for winding a base film on which a thin film is formed in the film forming chamber unit,
Of the optical characteristics in the width direction of the thin film formed on the base film, which is provided after at least one of the film forming chamber units and the base film is continuously supplied in the longitudinal direction, the reflection characteristics. And a measuring unit that measures the spectrum of
A supply unit that is provided with a plurality of gas nozzles in the width direction of the base film and supplies reactive gas in the vicinity of the target.
A control unit that controls the flow rate of the reactive gas ejected from the plurality of gas nozzles based on the reflection characteristic in the width direction in the measurement unit is provided.
Wherein the measuring unit includes a light projecting unit for irradiating light from an oblique direction with respect to the thin film on the base film, light receiving the reflected light from the oblique direction from the thin film on the base film An optical head having a part is provided, and
In the optical film, a polarizing film is formed between the base film and the thin film, and the reflected light of only the thin film is measured.
In the control unit, when there is a difference between the spectrum measured by the measurement unit and the desired spectrum, any of the film forming units is provided so that the wavelength deviation corresponding to the difference is within the desired range. A method for producing an optical film for adjusting the flow rate of the reactive gas supplied to the water. The first aspect of claim 1, wherein the measuring unit is further provided with a measuring roll having a light absorbing surface that absorbs light from the light projecting unit that passes through the base film, the polarizing film, and the thin film. Method of manufacturing an optical film. The method for producing an optical film according to claim 2, wherein the measurement roll is a black roll. The method for manufacturing an optical film according to any one of claims 1 to 3 , wherein the optical head has a polarizing plate that polarizes the light emitted from the light projecting unit. The method for producing an optical film according to claim 1, wherein the gas nozzle is a mixture of the reactive gas and a carrier gas and ejected. The gas nozzle is provided with a plurality of openings, a gas pipe for a reactive gas, a gas pipe for a carrier gas, and a mixing chamber inside, and the reactive gas and the carrier gas are mixed in the mixing chamber, and the plurality of gas nozzles are mixed. The method for producing an optical film according to claim 5 , wherein the mixed gas is ejected from the opening of the above. The gas pipe for the reactive gas includes a connecting portion for introducing gas and a pipe branched in a tournament shape so that the openings of the pipe are evenly spaced from the connecting portion.
The method for manufacturing an optical film according to claim 6 , wherein the control unit introduces gas into the connecting unit via a mass flow controller and controls the flow rate of the gas ejected from the plurality of gas nozzles.

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