JP6542970B2 - Method of manufacturing antireflective film - Google Patents

Description

  The present invention relates to a method for producing an antireflective film in which a thin film is formed 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, in the case of producing an antireflective film, a plurality of low refractive materials such as SiO ₂ and MgF and high refractive materials such as Nb ₂ O ₅ and TiO ₂ are formed to adjust the film thickness of each layer. The optical film is continuously formed on the base film so as to have a thin film configuration optically designed in advance.

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

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

  The present invention has been proposed in view of such conventional circumstances, and provides a method of manufacturing an antireflective film capable of forming a thin film having a uniform thickness in the width direction.

In order to achieve the above-mentioned object, the method for producing an antireflective film according to the present invention is a method for producing an antireflective film for forming an antireflective film composed of multiple thin films on a polarizing film using a thin film forming apparatus. (A) A predetermined sputtering chamber provided in the thin film forming apparatus is energized to target a thin film of any single layer of the antireflective film consisting of the thin film of the multilayer on the adjustment base film (B) measuring the reflection characteristics of the thin film of the single layer in the width direction to determine that the peak wavelength or bottom wavelength of the reflection spectrum falls within a desired range; And (4) repeating the above-mentioned step (i) and the above-mentioned step (ii) for any other layer, and (iv) all the predetermined sputtering chambers used in the steps (ii) to (iii). Energize, multi-layered on the adjustment base film And forming the anti-reflection film made of film, and a step of confirming that corresponds to (e) the reflective properties of the width direction of the antireflection film was measured, ranging peak wavelength and color of the reflection spectrum of the desired (H) adjusting the gas flow rate and sputtering voltage of the corresponding sputtering chamber when the desired range is not included in the step (E), and (G) adjusting the base film for adjusting the polarizing plate film And the step of carrying out the main film formation.

  In the method for producing an antireflective film according to the present invention, in the steps (i) to (iii), the film speed is decreased to increase the thickness of the formed film, and the optical thickness distribution in the width direction is adjusted. I am afraid.

  Further, in the method for producing an antireflective film according to the present invention, in the step (b), the film speed is set so that the peak wavelength or the bottom wavelength of the reflection spectrum is in the range of 450 nm to 650 nm. In the step (f), the flow rate of the gas and the sputtering voltage may be adjusted so that the peak wavelength or the bottom wavelength of the reflection spectrum in the width direction of the single layer in each layer is within ± 15 nm. You may do it.

  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 uniform thickness in the width direction Thin films 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. FIG. 1 shows an optical measurement system. It is a figure which shows an example of an optical head. It is a figure which shows the other example of an optical head. It is sectional drawing which shows the outline of a sputter | spatter chamber. It is a perspective view of a protection board. It is a disassembled perspective view of a gas nozzle. It is a figure which shows the control system which controls the gas flow rate of a sputter | spatter 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 anti-reflective film in an Example. It is a graph which shows the peak wavelength of the width direction of the 5th SiO ₂ single layer. It is a graph which shows the relationship between the film thickness of 2nd layer, and a reflection spectrum. It is a graph which shows the relationship between the film thickness of 2nd layer, and a hue. It is a graph which shows the relationship between the film thickness of 2nd layer, and Y value. It is a graph which shows the relationship between the film thickness of 3rd layer, and a reflection spectrum. It is a graph which shows the relationship between the film thickness of a 3rd layer, and a hue. It is a graph which shows the relationship between the film thickness of 3rd layer, and Y value. It is a graph which shows the relationship between the film thickness of a 4th layer, and a reflection spectrum. It is a graph which shows the relationship between the film thickness of a 4th layer, and a hue. It is a graph which shows the relationship between the film thickness of 4th layer, and Y value. It is a graph which shows the relationship between the film thickness of a 5th layer, and a reflection spectrum. It is a graph which shows the relationship between the film thickness of a 5th layer, and a hue. It is a graph which shows the relationship between the film thickness of 5th layer, and Y value.

Hereinafter, embodiments of the present invention will be described in detail in the following order with reference to the drawings.
1. Thin film forming apparatus 1.1 Overall outline of thin film forming apparatus 1.2 Measurement section of optical characteristics 1.3 Sputtering chamber 1.4 Reactive gas supply unit 1.5 Control of sputtering chamber 2. Thin film formation method Method of producing optical film Example

<1. Thin film forming device>
In a thin film forming apparatus according to an embodiment of the present invention, a base material film is continuously supplied in the longitudinal direction, and a measurement unit that measures the optical characteristics in the width direction of the thin film formed on the base film A plurality of gas nozzles are provided in the width direction of the film, and the flow rate of reactive gas spouted from each gas nozzle is controlled based on the supply section for supplying reactive gas near the target and the optical characteristics in the width direction in the measurement section. A control unit is provided, and a thin film having a uniform thickness in the longitudinal direction and the width direction can be formed.

  In addition, as a specific configuration, there is provided a film forming unit including a supply unit, a sputter electrode for applying a voltage to the target, and a plasma measuring unit for measuring the emission spectrum of plasma in the width direction of the base film during film formation. It is preferable to have. Thus, 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 in the measurement unit and the emission spectrum in the plasma measurement unit. It becomes possible to form a thin film of more uniform thickness in the direction.

  In addition, as a specific configuration, a thin film is formed by an unwinding unit for unwinding the base film in the longitudinal direction, a film forming unit in which a plurality of film forming units are arranged in the longitudinal direction of the base film, and a film forming unit It is preferable to provide a winding unit that winds the base film. Thereby, a multilayer thin film can be formed from unwinding to winding of a base film. 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, it is possible to measure the optical properties of both a single layer thin film or a multilayer thin film.

  Hereinafter, the specific configuration of the thin film forming apparatus will be described in detail. A thin film forming apparatus shown as a specific example is one that is made to travel while winding a base film which is a base film around a can roll, and forms a thin film on the surface of the base film by sputtering.

<1.1 Overview of thin film deposition system>
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 an unwinding part, and takes up the base film 1 on which the thin film is formed by the winding roll 12 which is a winding part. 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 is adjustable to a predetermined degree of vacuum.

  The first film forming chamber unit and the second film forming chamber unit are provided with the first can roll 21 and the second can roll 22 respectively, and the film forming portion is opposed to the outer peripheral surface of the can rolls 21 and 22 A plurality of sputtering chambers SP1 to SP10 are fixed. In each of the sputtering chambers SP1 to SP10, a supply unit having a plurality of gas nozzles in the width direction of the base film 1 is provided while a predetermined target is mounted on the electrode as described later.

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

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

  The thin film forming apparatus having such a configuration delivers 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 transported, and takes up the film. By winding with the 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 rates of reactive gases from the respective gas nozzles provided in the width direction based on the optical characteristics. By controlling the film thickness, it is possible to form a thin film of uniform thickness in the longitudinal direction and the width direction.

<1.2 Measurement section of optical characteristics>
Next, an optical measurement system for measuring optical characteristics by the optical monitors 31 and 32 will be described. FIG. 2 shows 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. And a measurement control unit 37 for outputting a measurement result of a desired spectrum.

  The optical measurement unit 33 transmits the base film through an optical head 331 having a light projecting unit that emits light to the thin film on the base film, and a light receiving unit that receives reflected light from the thin film on the base film. And a measuring roll 335 having a light absorbing surface for absorbing the light. Measuring the reflection characteristics such as reflectance, reflection hue, peak wavelength and bottom wavelength of reflection spectrum in the width direction of the thin film formed on the base film by moving the optical head 331 in the width direction of the base film Can.

  As a specific configuration, a cam follower 332 is attached to the optical head 331 so as to run in mesh with the cam groove of the traverse cam 333. The traverse cam 333 is connected to the drive unit 34, and a spiral or reverse spiral cam groove is engraved on the longitudinal surface. In addition, a guide rail 334 is provided to ensure stable travel of the cam follower 332. The cam follower 332 reciprocates on the traverse cam 333 by the rotational movement or the one-way rotational movement in which the traverse cam 333 is reversed at a constant interval, and the optical head 331 attached to the cam follower 332 is attached to the guide rail 334 Travel along a round trip. The measurement roll 335 is a so-called black roll with low surface reflection, and absorbs 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 according to an instruction from the measurement control unit 37. The light source 35 guides light to the optical head 331 through an optical fiber. In addition, the spectroscope 36 receives light from the optical head 331 via an optical fiber, and measures the spectrum and 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, reflection hue, and peak wavelength / bottom wavelength of the reflection spectrum. In addition, the optical head 331 is moved to a predetermined position in the width direction of the base film to obtain reflection characteristics at the predetermined position. For example, by measuring 25 points at intervals of 50 mm in the width direction, it is possible to measure the reflection characteristics of the base film of 1300 mm width in the width direction.

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

  FIG. 4 is a view showing another example of the optical head. This optical head is a biaxial optical system having a light projecting portion 39 for irradiating light to the thin film on the base film in an oblique direction, and a light receiving portion 40 for receiving the reflected light of the light irradiated from the oblique direction. is there. In addition, in the optical head of the biaxial optical system, a polarizing plate 39 a that polarizes the light emitted from the light emitting unit 39 is disposed. Thereby, only the AR film characteristic on a polarizing film can be measured to a multilayer substrate in which a polarizing film and an AR film are formed in this order on a transparent substrate.

<1.3 Sputtering chamber>
Next, the sputtering chamber fixed so as to face the outer peripheral surface of the can rolls 21 and 22 will be described. As a sputtering method used in the sputtering chamber, a magnetron sputtering method, a two-pole sputtering method only using plasma generated by direct current glow discharge or high frequency, a three-pole sputtering method adding a hot cathode, or the like can be used.

  In the present embodiment, it is preferable to use a magnetron sputtering method from the viewpoint of increasing the deposition rate. In the magnetron sputtering method, the magnetic field confines the plasma and increases 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 a high density plasma near the target. It is possible to enable speeding up of the membrane speed.

  FIG. 5 is a schematic cross-sectional view of the sputtering chamber. In this sputtering chamber, a pair of targets 41a and 41b can be installed, and magnetic field sources 42a and 42b for forming a magnetic field on the target surface, sputter electrodes 43a and 43b for applying to the target, and gas in the vicinity of the targets It has the supply parts 44a and 44b, and the adhesion prevention plate 45 which prevents the film deposition on the unnecessary part.

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

  The magnetic field sources 42a and 42b consist of permanent magnets or electromagnets, and make it possible to use a magnetron discharge in which the electric field and the magnetic field are orthogonal. For example, on a substantially oval flat plate provided parallel to the sputtering surface of the target, a central magnet disposed on the center line extending in the longitudinal direction, and an annular (endless) disposed so as to surround the periphery of the central magnet And the surrounding magnets are installed with different polarities.

  Sputtering electrodes 43a and 43b each have a pair of cathode / anode arranged with a length substantially the same as the width of the base film. Further, a negative DC voltage or a high frequency voltage can be applied to the target by a known structure.

  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 a 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, or a mixed gas of these or the like is used.

  The adhesion preventing plate 45 is disposed between the base film on the can roll and the target, and is substantially the same as, for example, a rectangle formed of 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. With a window of size. The adhesion preventing plate 45 is electrically floated from the anode / cathode, and the material is not particularly limited as long as it has heat resistance.

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

  According to the sputtering chamber having such a configuration, since the pair of targets 41a and 41b can be installed in one film forming chamber, it is possible to improve the film forming speed and form a dense, stress-resistant film. Can.

  Moreover, the method of applying a voltage for performing sputtering between the cathode and the anode is not particularly limited, and a method of applying an alternating voltage between two targets, a voltage with a DC pulse power supply to one target , And a so-called bipolar DMS method in which voltage application is alternately performed by a DC pulse power supply to two targets. For example, when an alternating 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, and glow discharge is caused between the anode electrode and the cathode electrode to form a plasma atmosphere. Be done. Here, the magnetic field generated by the magnetic field sources 42a and 42b confines the plasma and increases the path length of the electrons moving under the influence of the electric field, thereby increasing the probability of gas atom-electron collision, and in the vicinity of the target. A high density plasma is generated. Then, ions in the plasma atmosphere are accelerated toward one of the targets 41a and 41b which has become cathode electrodes and impacted, and the target atoms are scattered, whereby a thin film is formed on the surface of the base film.

<1.4 Reactive gas supply unit>
Next, in the sputtering chamber, 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 will be described.

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

  The gas pipe 51 for reactive gas includes a connecting portion for introducing the gas and piping branched from the connecting portion in a tournament shape so that the openings 51a of the pipe are equally spaced, and the gas is supplied via the mass flow controller 55 The gas is introduced uniformly from the plurality of openings 51a via the piping branched into a tournament shape. Further, the structure of the carrier gas gas pipe 52 is not particularly limited, but is preferably the same as 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 the separate 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 equal flow rates, and the reactive gas and the carrier gas can be made uniform in the mixing chamber 53. The mixed gas can be ejected from the respective openings 50a at a uniform flow rate. In addition, since the gas is introduced to the connection portion of the gas pipe 51 via the mass flow controller, the flow rate of gas from each gas nozzle installed in the longitudinal direction of the target, that is, the width direction of the base film can be controlled.

<1.5 Control of the sputtering chamber>
FIG. 8 is a diagram showing a control system for controlling the flow rate of gas in the sputtering chamber. This control system includes a supply unit 44a, 44b having a plurality of gas nozzles, a mass flow controller 55 for controlling the mass flow rate of gas introduced to each gas nozzle, and a plasma emission monitor 56 which is a plasma measurement unit for measuring the emission spectrum of plasma. And a controller 57 for controlling 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 across the nozzle width, and the gas nozzle openings in the longitudinal direction of the target, ie, the width direction of the base film It is arranged to be an interval. The number of gas nozzles arranged in the width direction of the base film is preferably equal to or more than the number of measurement windows for measuring the emission spectrum of plasma described later. Further, it is preferable that the gas nozzles located at symmetrical positions sandwiching the target introduce the gas output from the same mass flow controller 55.

  The mass flow controller 55 measures the mass flow rate of the gas introduced to 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 is 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. In the sputtering chamber, a plurality of transparent measurement windows are provided in the longitudinal direction of sputtering, ie, in the width direction of the base film, and light is introduced from this measurement window to an intermediate position between the base film and the target facing the target. Measure the spectral intensity of the emission spectrum of the plasma generated inside.

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 characteristic 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 the control, the flow rate of O ₂ gas and the voltage applied to the Si target are controlled. For example, when Nb ₂ O ₅ is formed by using Nb as a target and O ₂ as a reactive gas, the film thickness distribution based on the optical characteristics in the width direction of Nb ₂ O ₅ and Nb _{2 for} plasma light emission The flow rate of O ₂ gas and the voltage applied to the Nb target are controlled based on the intensity of the main spectrum of O ₅ .

  The control system having such a configuration has a plurality of points for measuring the optical characteristics of the thin film in the width direction of the base film and a plurality of points for measuring the emission spectrum of the plasma, and the width direction of the base film as a means for correcting the film thickness. Since a plurality of gas nozzles capable of controlling the flow rate of the reactive gas are provided, 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 thin film forming apparatus described above will be described.

  The thin film forming method according to the embodiment of the present invention is a measuring process in which a substrate film is continuously supplied in the longitudinal direction and the optical characteristics in the width direction of the thin film formed on the substrate film are measured by a measuring device. And controlling the flow rate of the reactive gas ejected from each of the 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 apparatus, and forming a thin film. Thus, a thin film having a uniform thickness in the width direction can be formed.

  Here, in the measurement step, the emission spectrum of plasma in the width direction of the substrate film during film formation is measured, and in the deposition step, each gas nozzle is based on the optical characteristics of the width direction and the emission spectrum of plasma in the width direction. It is preferable to control the flow rate of the reactive gas spouted from the chamber and the voltage applied to the target. As a result, it is 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. Method of producing optical film>
Next, the manufacturing method of the optical film which manufactures a multilayer optical film using the thin film forming apparatus mentioned above is demonstrated.

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

The film thickness (optical thickness) of each layer to be a target is determined in advance by optical simulation. For example, when an antireflective 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 35 nm, and the fourth layer Nb ₂ O By setting ₅ to 35 nm and the fifth SiO ₂ layer to 100 nm, it can function as an antireflective film.

The specific method of forming the anti-reflective film which consists of a multilayer thin film on a polarizing film using the thin film forming apparatus mentioned above is as follows.
(A) A step of energizing a predetermined sputtering chamber to form an arbitrary single-layer thin film of a multi-layered thin film on a substrate film for adjustment thicker than a target thickness (b) Measuring the reflection characteristics of the thin film of a single layer, and confirming that the peak value (or the bottom value) of the reflection spectrum falls within the desired range (iii) for any other layer B) Repeating step (d): All the predetermined sputtering chambers used in the above (i) to (iii) are energized to form an antireflection film consisting of a multilayer thin film on the substrate film for adjustment (E) Step of measuring the reflection characteristics of the anti-reflection film and confirming that the peak value and the hue of the reflection spectrum fall within the desired range (to) If not applicable, the gas flow rate of the corresponding sputtering chamber, sputtering Step of adjusting voltage (g) Base material for adjusting Step of Irumu, switch to the polarizer film, performs the film

  In the steps (i) to (iii), the film speed is reduced to increase the film thickness and the optical thickness distribution in the width direction is adjusted, whereby the film speed faster than the step (i) in the step (ii) The optical thickness distribution in the width direction when forming a multilayer antireflection film can be made uniform.

  In the step (ii), it is preferable to set the film speed such that the peak wavelength or bottom wavelength of the reflection spectrum is in the range of 450 nm to 650 nm. In addition, it is preferable to adjust the gas flow rate, the 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 in each layer is within ± 15 nm. By adjusting the reflection characteristics in such a range, it is possible to form an antireflective film in which a desired spectrum is 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 antireflective film was formed on the polarizing plate as an optical film. The present invention is not limited to the following examples.

The film thickness (optical thickness) of each layer of the antireflective 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, the third layer SiO ₂ 35 nm, and the fourth layer The Nb ₂ O ₅ of the eye was set to 35 nm, and the SiO ₂ layer of the fifth layer was set to 100 nm.

FIG. 10 is a cross-sectional view showing the configuration of the antireflective film in the example. In the thin film forming apparatus shown in FIG. 1, this anti-reflection film is formed of the first SiO _x sputtering chamber SP1, the second Nb ₂ O ₅ sputtering chamber ₂ , the third SiO ₂ sputtering chamber SP3, SP4,4 layer of _Nb 2 _{O 5} sputter chamber SP5, the SiO ₂ of SP6,5-layer was deposited by sputtering chamber SP7～SP10. The base film used had a width of 1300 mm.

  First, as shown in Table 1, the film speed of each layer was set, and a single layer thin film was formed thicker than the target thickness. Then, the reflection characteristics of the thin film of a single layer 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 becomes the range of the 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 SiO ₂ single layer. This graph is obtained by measuring 25 points of the peak wavelength at regular intervals on a base film having a width of 1300 mm.

  Next, the sputtering chambers SP1 to SP10 were all energized, the film speed was 1.8 m / min, and an antireflection layer consisting 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 adjusted so that the peak value and the hue of the reflection spectrum fall within the desired range.

  12 to 23 are graphs showing the correlation between film thickness fluctuation and hue fluctuation of each layer of the antireflective 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. 15 to 17 are graphs showing the relationship between the film thickness of the third layer and the reflection spectrum, 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 thickness of the fourth layer and the reflection spectrum, the relationship between the thickness and the hue, and the relationship between the thickness and the Y value, respectively. 21 to 23 are graphs showing the relationship between the film thickness and reflection spectrum of the fifth layer, the relationship between film thickness and hue, and the relationship between film thickness and Y value, respectively.

  After adjusting the sputtering chambers SP1 to SP10 based on the simulation results shown in FIG. 12 to FIG. 23, the base film for adjustment was switched to a polarizing plate film, and main film formation was performed. For example, when there is a difference between the spectrum of the main deposition and the desired (best) spectrum at a predetermined position in the width direction, the discharge conditions were finely adjusted using the simulation results of FIGS. Specifically, the reaction gas flow rate at a predetermined position of the cathode corresponding to a wavelength that deviates from the spectrum of the best was adjusted. The adjustment of the reaction gas flow rate was performed by estimating the amount of increase or decrease with reference to the simulation, confirming the spectrum of the changed result with the optical monitor 32, and repeating this adjustment until the spectrum of Best was approximated. As a result, it was possible to obtain the desired antireflection film spectrum 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. In addition, the adjustment of the single layer film and the adjustment of the multilayer film described above made it possible to start main film formation with a desired spectrum within 2 hours.

  DESCRIPTION OF SYMBOLS 1 base film, 11 unwinding roll, 12 take-up 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 adhesion plate, 50 gas nozzle, 51 gas pipe for reactive gas, 52 gas pipe for carrier gas, 55 mass flow controller, 56 plasma light emission monitor, 57 controller

Claims (4)

A method for producing an antireflective film, comprising forming a multi-layered thin film antireflective film on a polarizing film using a thin film forming apparatus,
(A) By energizing a predetermined sputtering chamber provided in the thin film forming apparatus, a target thickness of a thin film of any single layer of the above-mentioned antireflective film consisting of the thin film of the multiple layers is targeted on the adjustment base film Thick forming process,
(B) measuring the reflection characteristics in the width direction of the thin film of the single layer, and confirming that the peak wavelength or bottom wavelength of the reflection spectrum falls within a desired range;
(C) repeating the above step (i) and the above step (ii) for any other layer;
(D) applying electricity to all of the predetermined sputtering chambers used in the steps (i) to (iii) to form the antireflective film composed of a multi-layered thin film on the adjusting base film;
(E) measuring the reflection characteristics in the width direction of the anti-reflection film to confirm that the peak wavelength and hue of the reflection spectrum fall within a desired range;
(F) adjusting the flow rate of gas in the corresponding sputtering chamber and the sputtering voltage when the desired range is not included in the step (e);
(G) A method for producing an antireflective film, comprising the steps of: switching the substrate film for adjustment to a polarizing plate film and performing a main film formation.   The method according to claim 1, wherein in the steps (i) to (iii), the film thickness is increased by decreasing the film speed to adjust the optical thickness distribution in the width direction.   The method according to claim 2, wherein in the step (ii), the film speed is set so that the peak wavelength or the bottom wavelength of the reflection spectrum is in the range of 450 nm to 650 nm.   In the step (f), the flow rate of the gas and the sputtering voltage are adjusted so that the peak wavelength or the bottom wavelength of the reflection spectrum in the width direction of the single layer in each layer is within ± 15 nm. The manufacturing method of the anti-reflective film in any one of 3.

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