JP2014034701A - Thin film deposition device and thin film deposition method - Google Patents

Abstract

A thin film forming apparatus and a thin film forming method capable of forming a thin film having a uniform thickness in the width direction are provided.
Optical monitors 31 and 32 for measuring optical characteristics in the width direction of a thin film formed on a base film 1 and a plurality of gas nozzles in the width direction of the base film are provided to supply a reactive gas in the vicinity of the target. And a sputtering electrode for applying a voltage to the target, and a plurality of sputtering chambers SP1 to SP10 arranged in the longitudinal direction of the base film, and based on the optical characteristics of the optical monitors 31 and 32 in the width direction. Thus, the flow rate of the reactive gas ejected from each gas nozzle is controlled.
[Selection] Figure 1

Description

  The present invention relates to a thin film forming apparatus and a thin film forming apparatus for forming 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 (for example, see Patent Documents 1 and 2). For example, when producing an antireflection 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, and the entire film thickness is adjusted while adjusting the film thickness of each layer. As described above, an optical film is continuously formed on a base film so as to have a thin film structure optically designed in advance.

JP 2000-080185 A JP 2007-224322 A

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

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

  In order to achieve the above-described object, the thin film forming apparatus according to the present invention measures the optical characteristics in the width direction of the thin film formed on the base film by continuously supplying the base film in the longitudinal direction. A measurement unit, a supply unit that is provided with a plurality of gas nozzles in the width direction of the base film, and that supplies reactive gas in the vicinity of the target, and a reaction that is ejected from each gas nozzle based on optical characteristics in the width direction of the measurement unit And a control unit for controlling the flow rate of the sex gas.

  Further, the thin film forming method according to the present invention includes 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 with a measuring device; And forming a thin film by controlling the flow rate of the reactive gas ejected from each gas nozzle provided in the width direction of the base film based on the optical characteristics in the width direction of the measuring device. It is characterized by.

  Moreover, the manufacturing method of the optical film which concerns on this invention is the manufacturing method of the optical film which manufactures a multilayer optical film using the said thin film formation apparatus, A base film is continuously made into a longitudinal direction at 1st speed. Supply, forming a single-layer thin film for each layer, adjusting the optical thickness distribution in the width direction of the base film to a predetermined range, and a second speed higher than the first speed in the longitudinal direction of the base film And an optical film forming step of forming a multilayer thin film continuously.

  According to the present invention, since the flow rate of the reaction gas from each gas nozzle provided in the width direction is controlled 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. The thin film can be formed.

1 is a perspective view showing an outline of a thin film forming apparatus according to an embodiment of the present invention. It is a figure which 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 sputtering chamber. It is a perspective view of an adhesion prevention board. It is a disassembled perspective view of a gas nozzle. It is a figure which shows the control system which controls the flow volume of the gas of 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 anti-reflective film in an Example. 5-layer SiO ₂ is a graph showing a peak wavelength in the width direction of the single layer. It is a graph which shows the relationship between the film thickness of a 2nd layer, and a reflection spectrum. It is a graph which shows the relationship between the film thickness of a 2nd layer, and a hue. It is a graph which shows the relationship between the film thickness of a 2nd layer, and Y value. It is a graph which shows the relationship between the film thickness of a 3rd layer, and a reflection spectrum. It is a graph which shows the relationship between the film thickness of 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 4th layer, and a hue. It is a graph which shows the relationship between the film thickness of the 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 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. 1. Thin Film Forming Apparatus 1.1 Overall Outline of Thin Film Forming Apparatus 1.2 Optical Characteristic Measurement Unit 1.3 Sputter Chamber 1.4 Reactive Gas Supply Unit 1.5 Sputter Chamber Control 2. Thin film formation method 3. Manufacturing method of optical film Example

<1. Thin film forming equipment>
A thin film forming apparatus according to an embodiment of the present invention includes a measuring unit that continuously supplies a base film in the longitudinal direction and measures the optical characteristics in the width direction of the thin film formed on the base film, and the base 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 supply unit that supplies the reactive gas near the target and the optical characteristics in the width direction of the measurement unit. And a control unit, which 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 unit having a supply unit, a sputtering 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 provide. Thereby, 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 having a uniform thickness depending on 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 deposition unit in which a plurality of deposition units are arranged in the longitudinal direction of the base film, and the deposition unit. It is preferable to include a winding unit that winds up the base film that has been formed. Thereby, a multilayer thin film can be formed from unwinding of a base film to winding-up. The measurement 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 multilayer thin film can be measured.

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

<1.1 Outline of Thin Film Forming Apparatus>
FIG. 1 is a perspective view schematically showing a thin film forming apparatus according to an embodiment of the present invention. In this thin film forming apparatus, the base film 1 is supplied from an unwinding roll 11 that is an unwinding part, and the base film 1 on which the thin film is formed is wound by a winding roll 12 that is a winding part. In addition, a first film formation chamber unit and a second film formation chamber unit which are film formation 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.

  Each of the first film forming chamber unit and the second film forming chamber unit includes a first can roll 21 and a second can roll 22, and the film forming unit is disposed so as to face the outer peripheral surfaces of the can rolls 21 and 22. A plurality of sputtering chambers SP1 to SP10 are fixed. As will be described later, each of the sputtering chambers SP <b> 1 to SP <b> 10 is provided with a supply unit having a plurality of gas nozzles in the width direction of the base film 1 while a predetermined target is attached on the electrode.

  In addition, the thin film forming apparatus includes an optical monitor 31 that is a measurement unit that measures optical characteristics between the first film formation chamber unit and the second film formation chamber unit, that is, after film formation by the sputtering chamber SP5. Thereby, the film formation of the intermediate product after the first film formation chamber unit can be controlled, and the adjustment time at the time of adjustment by a single layer to be described later can be reduced. In addition, an optical monitor 32 is provided as a measurement unit that measures optical characteristics after the second film formation chamber unit, that is, after film formation by the sputtering chamber SP10. 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 in the width direction of the thin film formed on the base film 1 using an optical head that can scan in the width direction. By using the optical monitors 31 and 32, for example, the peak wavelength of reflectance is measured as an optical characteristic and converted into an optical thickness, whereby an optical thickness distribution in the width direction can be obtained.

  The thin film forming apparatus having such a configuration feeds 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 film. By winding with the roll 12, a multilayer thin film can be obtained. Here, the optical characteristics in the width direction of the thin film formed on the base film 1 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 based on the optical characteristics. By controlling this, a thin film having a uniform thickness in the longitudinal direction and the width direction can be formed.

<1.2 Optical characteristic measurement unit>
Next, an optical measurement system that measures optical characteristics using the 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 that moves the optical head 331 in the width direction of the base film, a light source 35 that supplies light to the optical head 331, and light reception by the optical head 331. A spectroscope 36 for measuring the spectrum of the light and a measurement control unit 37 for outputting a measurement result of the desired spectrum.

  The optical measuring unit 33 transmits an optical head 331 having a light projecting unit that irradiates light to a thin film on the base film, a light receiving unit that receives reflected light from the thin film on the base film, and the base film. And a measuring roll 335 having a light absorption surface that absorbs the absorbed light. Measuring reflection characteristics such as reflectance, reflection hue, peak wavelength / bottom wavelength of reflection spectrum, etc. 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 do.

  As a specific configuration, a cam follower 332 is attached to the optical head 331 so as to 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 formed on the surface in the longitudinal direction. In addition, a guide rail 334 is provided in order to make the cam follower 332 run stably. Then, the cam follower 332 reciprocates on the traverse cam 333 by a rotational motion in which the traverse cam 333 reverses at a constant interval or a rotational motion in one direction, and the optical head 331 attached to the cam follower 332 moves to the guide rail 334. Travel back and forth along. 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 light measurement control unit 37 and moves the optical head 331 to a predetermined position in the width direction of the base film according to a command from the measurement control unit 37. The light source 35 guides light to the optical head 331 through an optical fiber. The spectroscope 36 receives light from the optical head 331 via an optical fiber and measures a spectrum and the like. The measurement control unit 37 performs arithmetic processing on the spectrum in the spectroscope 36 and outputs reflection characteristics such as reflectance, reflection hue, 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 reflection characteristics at the predetermined position. For example, by measuring 25 points at intervals of 50 mm in the width direction, the reflection characteristics of a base film having a width of 1300 mm can be measured in the width direction.

  FIG. 3 is a diagram illustrating an example of the optical head. This optical head is a coaxial optical system 38 in which a light projecting unit and a light receiving unit are coaxially arranged. The 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) or TAC (Tri Acetyl Cellulose).

  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 light from an oblique direction to a thin film on a base film, and a light receiving unit 40 that receives reflected light of the light irradiated from the oblique direction. is there. The biaxial optical head has a polarizing plate 39 a that polarizes light emitted from the light projecting unit 39. Thereby, only the AR film characteristic 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 base material.

<1.3 Sputtering chamber>
Next, the sputtering chamber fixed so as to face the outer peripheral surfaces 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 using only plasma generated by direct current glow discharge or high frequency, a three-pole sputtering method using 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 magnetron sputtering, the magnetic field confins the plasma and increases the path length of electrons moving under the influence of an 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 schematically showing the sputtering chamber. In this sputtering chamber, a pair of targets 41a and 41b can be installed, magnetic field generating sources 42a and 42b for forming 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. Supplying parts 44a and 44b to be supplied and a deposition preventing plate 45 for preventing deposition of a film on unnecessary portions are provided.

  The targets 41a and 41b are appropriately selected according to 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 a permanent magnet or an electromagnet, and can use a magnetron discharge in which an electric field and a magnetic field are orthogonal to each other. For example, on a substantially oval flat plate provided in parallel to the sputtering surface of the target, a central magnet arranged on the center line extending in the longitudinal direction and an annular (endless) shape surrounding the central magnet Peripheral magnets with different polarity are installed.

  Each of the sputter electrodes 43a and 43b has a pair of cathode / anode arranged with a length substantially the same as the width of the base film. And 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 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 thereof is used.

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

  6 is a perspective view of the adhesion-preventing plate shown in FIG. As shown in FIG. 5, the deposition preventing 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 an opening 45c on the outer upper surface of the window. By providing the opening in the deposition preventing 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 strong film can be formed. Can do.

  The method for applying a voltage for performing sputtering between the cathode and the anode is not particularly limited. A method for applying an AC voltage between two targets, and a DC pulse power supply applied to one target. For example, a so-called bipolar DMS method in which voltage is alternately applied to two targets by a DC pulse power source 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 between an anode electrode and a cathode electrode, and a glow discharge is generated between the anode electrode and the cathode electrode to form a plasma atmosphere. Is done. Here, the magnetic field generated by the magnetic field generation 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 and bombarded toward one of the targets 41a and 41b that have become cathode electrodes, and target atoms are scattered to form a thin film on the surface of the base film.

<1.4 Reactive gas supply unit>
Next, the supply units 44a and 44b including 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 and ejects reactive gas and carrier gas. 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 therein, and the reactive gas and the carrier gas are mixed in the mixing chamber 53, and a plurality of openings are formed. A mixed gas is ejected from the opening 50a. A plurality of the mixing chambers 53 are installed in the longitudinal direction of the target, that is, 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 of the reactive gas includes a connecting part for introducing a gas and a pipe branched in a tournament shape so that the opening 51a of the pipe is equidistant from the connecting part, and the gas is supplied via the mass flow controller 55. Gas is uniformly discharged from the plurality of openings 51a through the pipes introduced from the connecting portion and branched into a tournament shape. 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 discharged from the plurality of openings 51a and the carrier gas discharged 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 are uniformly distributed in the mixing chamber 53. The mixed gas can be ejected at an equal flow rate from each opening 50a. Moreover, since gas is introduced into the connection part of the gas pipe 51 via a mass flow controller, the flow rate of the 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 Sputter chamber control>
FIG. 8 is a diagram showing a control system for controlling the gas flow rate 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 the gas introduced into 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 gas flow rate in the mass flow controller 55 and the voltage applied to the sputtering electrode.

  As described above, the supply units 44a and 44b are gas nozzles having a so-called tournament structure for jetting gas at a uniform flow rate over the entire nozzle width, and the gas nozzle openings in the longitudinal direction of the target, that is, in the width direction of the base film. It arrange | positions so that it may become a space | interval. 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 described later. Moreover, it is preferable that the gas nozzle in a symmetrical position across the target introduces the gas output from the same mass flow controller 55.

  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 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, that is, in the width direction of the base film, and light is introduced into the intermediate position between the measurement film 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 O ₂ gas and the voltage applied to the Si target are controlled. For example, when Nb is used as the target, O ₂ is used as the reactive gas, and Nb ₂ O ₅ is formed, the film thickness distribution based on the optical characteristics in the width direction of Nb ₂ O ₅ and the Nb _{2 of} plasma emission. Based on the intensity of the main spectrum of O ₅ , the flow rate of O ₂ gas and the voltage applied to the Nb target are controlled.

  The 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 the plasma in the width direction of the base film, and the width direction of the base film as a means for correcting the film thickness. Since the plurality of gas nozzles capable of controlling the flow rate of the reactive gas are provided, a thin film having a uniform thickness in the width direction can be formed.

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

  The thin film formation method according to the embodiment of the present invention is a measurement process 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 with a measuring device. And a film forming step of forming a thin film by controlling the flow rate of the reactive gas ejected from each gas nozzle provided in the width direction of the base film based on the optical characteristics in the width direction of the measuring apparatus. Thereby, a thin film having a uniform thickness in the width direction can be formed.

  Here, in the measurement process, the emission spectrum of the plasma in the width direction of the base film during film formation is measured, and in the film formation process, 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 and the voltage applied to the target. As a result, it is possible to form a wide and long optical film with an error that the optical thickness in the width direction is ± 3% or less.

<3. Manufacturing method of optical film>
Next, an optical film manufacturing method for manufacturing a multilayer optical film using the above-described 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 manufacturing an optical film according to the embodiment of the present invention, a base film is continuously supplied at a first speed in the longitudinal direction, a single-layer thin film is formed for each layer, and the width direction of the base film is An adjusting step S1 for adjusting the optical thickness distribution to a predetermined range, and an optical film forming step S2 for 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 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. 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 comprising a multilayer thin film on a polarizing film using the above-described thin film forming apparatus is as follows.
(A) A process of energizing a predetermined sputtering chamber to form an arbitrary single-layer thin film out of a multi-layered antireflection film thicker than a target thickness on a substrate film for adjustment (b) Step (c) for confirming that the peak value (or bottom value) of the reflection spectrum falls within a desired range by measuring the reflection characteristics of the single-layer thin film. Step (b) is repeated (d) All the predetermined sputtering chambers used in (a) to (c) above are energized to form an antireflection film composed of a multilayer thin film on the base film for adjustment. (E) A step of measuring the reflection characteristics of the antireflection film and confirming that the peak value and hue of the reflection spectrum fall within a desired range (f) If not applicable, the gas flow rate of the corresponding sputtering chamber, sputtering Step for adjusting voltage (g) Base material for adjustment The Irumu, instead switch to the polarizer film, the step of performing the film

  In steps (ii) to (iii), by reducing the film speed to increase the film thickness and adjusting the optical thickness distribution in the width direction, the film speed in step (d) is faster than in step (ii). Thus, the optical thickness distribution in the width direction when the multilayer antireflection film is formed can be made uniform.

  In the step (b), the film speed is preferably set so that the peak wavelength or bottom wavelength of the reflection spectrum is in the range of 450 nm to 650 nm. Further, it is preferable to adjust the gas flow rate, sputtering voltage, etc. so that the peak wavelength or 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 within such a range, it is possible to form an antireflection film that can obtain a desired spectrum uniformly in the width direction of the base film.

<4. Example>
Examples of the present invention will be described below. 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 film thickness (optical thickness) of each layer of the antireflection film is obtained by optical simulation. 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. 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 example. In the thin film forming apparatus shown in FIG. 1, this antireflection film is formed by using the first SiO _x as the sputtering chamber SP1, the second Nb ₂ O ₅ as the sputtering chamber SP2, and the third SiO ₂ as the sputtering chamber SP3. SP4, Nb ₂ O ₅ of the fourth layer was deposited in the sputtering chamber SP5, SP6, and SiO ₂ of the fifth layer was deposited 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, and a single-layer thin film was formed 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 a specific wavelength range. 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 peak wavelengths at regular intervals on a 1300 mm wide base film.

  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 to fall within 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 of the second 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. 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 film thickness of the fourth 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. 21 to 23 are graphs showing the relationship between the film thickness of the fifth 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.

  Based on the simulation results shown in FIGS. 12 to 23, after adjusting the sputtering chambers SP <b> 1 to SP <b> 10, the base film for adjustment was switched to a polarizing film to perform main film formation. For example, when there is a difference between the spectrum of the main film formation 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 having a deviation from the best spectrum was adjusted. The reaction gas flow rate was adjusted by estimating the amount of increase / decrease 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 best spectrum. As a result, a desired spectrum of the antireflection film could be obtained with a width of 1100 mm.

  As described 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, the adjustment of the single layer film and the adjustment of the multilayer film described above enabled the start of the main film formation with a desired spectrum within 2 hours.

  DESCRIPTION OF SYMBOLS 1 Base film, 11 unwinding roll, 12 winding roll, 21 1st can roll, 22 2nd can roll, 31 Optical monitor, 32 Optical monitor, 41 Target, 42 Magnetic field generation source, 43 Sputter electrode, 44 Supply 45, deposition prevention plate, 50 gas nozzle, 51 gas pipe for reactive gas, 52 gas pipe for carrier gas, 55 mass flow controller, 56 plasma emission monitor, 57 controller

Claims (14)

A base film is continuously supplied in the longitudinal direction, and a measurement unit that measures 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 base film, and a supply unit that supplies reactive gas in the vicinity of the target;
A thin film forming apparatus comprising: a control unit that controls a flow rate of the reactive gas ejected from each gas nozzle based on optical characteristics in the width direction in the measurement unit. A deposition unit having the supply unit, a sputtering electrode that applies a voltage to the target, and a plasma measurement unit that measures a plasma emission spectrum in the width direction of the base film during deposition;
The said control part controls the flow volume of the reactive gas ejected from each gas nozzle, and the voltage applied to a target based on the optical characteristic of the width direction in the said measurement part, and the emission spectrum in the said plasma measurement part. Thin film forming equipment. An unwinding section for unwinding the base film in the longitudinal direction;
A film forming unit having the supply unit, a sputtering electrode for applying a voltage to the target, and a plasma measuring unit for measuring the emission spectrum of the plasma in the width direction of the base film during film formation is in the longitudinal direction of the base film. A plurality of film forming units;
A winding unit for winding the base film on which the thin film is formed in the film forming unit;
The thin film forming apparatus according to claim 1, wherein the measurement unit is installed at least between the film forming unit and the winding unit.   The measurement unit includes an optical head having a light projecting unit that irradiates light to the thin film on the base film, a light receiving unit that receives reflected light from the thin film on the base film, and the base film is transmitted. The light absorption surface which absorbs the light which was used, The said optical head is moved to the width direction of a base film, The reflection characteristic of the width direction of the thin film formed on this base film is measured. Thin film forming equipment.   The thin film forming apparatus according to claim 4, wherein the light projecting unit and the light receiving unit are arranged coaxially. The light projecting unit irradiates light from an oblique direction to the thin film on the base film,
The thin film forming apparatus according to claim 4, wherein the light receiving unit receives reflected light of light irradiated from the oblique direction.   The thin film forming apparatus according to claim 6, wherein the optical head includes a polarizing plate that polarizes light emitted from the light projecting unit.   The thin film forming apparatus according to claim 1, wherein the gas nozzle mixes and ejects a reactive gas and a carrier gas.   The gas nozzle includes a plurality of openings, a gas pipe for a reactive gas, a gas pipe for a carrier gas, and a mixing chamber, and mixes the reactive gas and the carrier gas in the mixing chamber. The thin film forming apparatus according to claim 8, wherein the mixed gas is ejected. The gas pipe for the reactive gas includes a connecting part for introducing gas, and a pipe branched in a tournament shape so that the openings of the pipe are equidistant from the connecting part,
The thin film forming apparatus according to claim 9, wherein the control unit introduces a gas into the coupling unit via a mass flow controller and controls a flow rate of the gas ejected from each gas nozzle. A measurement process in which the 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 with a measuring device;
Based on the optical characteristics in the width direction of the measuring device, the flow rate of the reactive gas ejected from each gas nozzle provided in the width direction of the base film is controlled to form a thin film. Method. In the measurement step, the emission spectrum of the plasma in the width direction of the base film during film formation is measured,
12. The thin film according to claim 11, wherein in the film forming step, the flow rate of the reactive gas ejected from each gas nozzle and the voltage applied to the target are controlled based on the optical characteristics in the width direction and the emission spectrum of the plasma in the width direction. Forming method. In the manufacturing method of an optical film which manufactures a multilayer optical film using the thin film forming apparatus according to any one of claims 1 to 10,
An adjustment step of continuously supplying the base film in the longitudinal direction at a first speed, forming a single-layer thin film for each layer, and adjusting the optical thickness distribution in the width direction of the base film to a predetermined range;
An optical film forming step of continuously supplying a base film in a longitudinal direction at a second speed higher than the first speed to form a multilayer thin film.   In the adjustment step, the optical thickness distribution in the width direction of the base film is adjusted to a predetermined range by adjusting each layer so that the peak wavelength or bottom wavelength of the reflection spectrum in the width direction of the single layer is within ± 15 nm. The method for producing an optical film according to claim 13.

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