JP2019163546A - Multilayer optical film thickness control method, multilayer optical film manufacturing method, and multilayer optical film sputtering apparatus - Google Patents

Abstract

To realize a film thickness control method for forming a multilayer optical film, in which the thicknesses of each of optical film in longitudinal direction and width direction of a substance may approach target values.SOLUTION: A regression equation representing relationship between thicknesses of optical films and optical characteristic values of a multilayer optical film is prepared, which is obtained by regression analysis of a theoretical optical characteristic value group of the multilayer optical films to which combinations with respective film thicknesses of optical films are assigned. A model equation representing relationship between change quantities of a manufacturing parameter and change quantities of the film thickness of the optical film is prepared. The optical characteristic values of a formed multilayer optical film at plural sites in a width direction are measured to obtain actually measured values. By applying the actually measured values to the regression equation, estimated film thickness deviations are calculated for the respective sites in the width direction. By applying the estimated film thickness deviations to the model equation, adjustment quantities of the manufacturing parameter at the respective sites in the width direction necessary to bring the film thickness deviation quantities of the respective optical films close to 0 are calculated. The manufacturing parameter is broken down to the plural sites in the width direction, to be changed based on the respective adjustment quantities.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a multilayer optical film thickness control method, a multilayer optical film manufacturing method, and a multilayer optical film sputtering apparatus.

  A multilayer optical film is a film in which a plurality of optical films are laminated. The multilayer optical film is manufactured by sequentially forming a plurality of optical films on a substrate. When forming a multilayer optical film, it is not always possible to form each optical film with a target thickness. Therefore, it is necessary to perform film formation while appropriately adjusting manufacturing parameters of each optical film. Therefore, Patent Document 1 (WO 2011/046050) discloses a method of adjusting manufacturing parameters using optical characteristics of a multilayer optical film that has already been formed.

  In Patent Document 1, three layers of a first transparent layer (high refractive index layer), a second transparent layer (low refractive index layer), and a transparent conductive layer are sequentially formed on a long film. The spectral reflectance of the multilayer optical film that has been formed is measured, and the sputtering conditions of the second transparent layer are controlled so that the difference from the target spectral reflectance is small. Thereby, the film thickness of the second transparent layer is changed, and the change in the spectral reflectance of the multilayer optical film is observed. The reason for changing the film thickness of the second transparent layer is that the adjustment of the film thickness of the second transparent layer is the easiest.

  If the multilayer optical film is about three layers, it may be possible to change the film thickness of only one specific layer to reduce the difference between the actual spectral reflectance and the target spectral reflectance. Even in that case, if the difference between the actual spectral reflectance and the target spectral reflectance is caused by the difference in film thickness between the other two layers from the target film thickness, the layer should not be changed originally. The film thickness will be changed and will not be adjusted properly. Further, when the number of layers of the multilayer optical film is increased, it is not practical to reduce the difference between the actual spectral reflectance and the target spectral reflectance only by changing the film thickness of one specific layer. Therefore, there is a limit to the method of Patent Document 1 in which only the film thickness of a specific layer is changed.

  When the width of the base material on which the multilayer optical film is formed becomes wider, variations in the film thickness in the width direction of each optical film cannot be ignored. However, as far as the inventors of the present application know, there is no document describing in detail how to reduce the variation in film thickness in the width direction. However, in reality, the variation in the film thickness in the width direction of the optical film is a big problem in mass production.

WO 2011/0446050 gazette

  It is an object of the present invention to form a multilayer optical film in the thickness direction of the base material (traveling direction of the base material) and the width direction (direction orthogonal to the traveling direction) for each optical film. Is to realize a film thickness control method capable of bringing the value close to the target value. Furthermore, a multilayer optical film manufacturing method using the control method and a sputtering apparatus using the control method are realized.

  The inventor of the present application considers a method of estimating the film thickness deviation of each optical film by making use of regression analysis, and a method of reducing the film thickness variation in the width direction by applying it, and the multilayer optical film of the present invention A film thickness control method, a multilayer optical film manufacturing method, and a multilayer optical film sputtering apparatus were completed.

[Multilayer optical film thickness control method]
(1) The multilayer optical film thickness control method of the present invention controls the film thickness of each optical film when the multilayer optical film formed by laminating a plurality of optical films is formed using a film forming apparatus. This is a film thickness control method. The multilayer optical film thickness control method of the present invention includes the following steps.
・ The film thickness of each optical film and the multilayer optical film obtained by regression analysis of the theoretical optical characteristic value group of the multilayer optical film in which the combination of film thicknesses of each optical film is comprehensively allocated within a predetermined range. Preparing a regression equation representing a relationship with a theoretical optical characteristic value;
A step of preparing a model equation representing a relationship between a change amount of manufacturing parameters used for forming each optical film and a change amount of the film thickness of the optical film in the film forming apparatus.
A step of measuring optical characteristic values at a plurality of positions in the width direction of the formed multilayer optical film and obtaining actual measurement values thereof.
A step of calculating the estimated film thickness deviation amount from the reference film thickness of each optical film at a plurality of positions in the width direction by applying the actual measurement value to the regression equation.
Apply the estimated film thickness deviation amount to the model formula, and calculate the adjustment amount of the manufacturing parameter at the plurality of positions in the width direction necessary to bring the film thickness deviation amounts at the plurality of positions in the width direction of each optical film close to 0. Step.
A step of changing the manufacturing parameter by dividing it into a plurality of locations in the width direction based on the adjustment amount.

  (2) The multilayer optical film thickness control method of the present invention is an optical film whose thickness changes with a certain time lag by dividing and changing the manufacturing parameters of each optical film at a plurality of locations in the width direction. Increases by one layer, the difference between the predicted value of the characteristic value calculated using the regression equation corresponding to the optical film whose thickness has changed and the actual measurement value is within the assumed range calculated by the regression equation. Including the step of confirming that.

  (3) The method for controlling the film thickness of the multilayer optical film of the present invention uses the lightness and / or color coordinates of the reflected light of the multilayer optical film as the optical characteristic value of the multilayer optical film.

  (4) The multilayer optical film thickness control method of the present invention uses a sputtering method when forming the multilayer optical film.

  (5) The film thickness control method for a multilayer optical film of the present invention uses plasma emission intensity as a manufacturing parameter to be changed when the multilayer optical film is formed.

  (6) In the multilayer optical film thickness control method of the present invention, the multilayer optical film is any one of a transparent conductive film, a photocatalyst film, a gas barrier film, and a light interference film.

[Method for producing multilayer optical film]
(7) The method for producing a multilayer optical film of the present invention is a method for forming a multilayer optical film formed by laminating a plurality of optical films using a film forming apparatus, and includes the following steps.
・ The film thickness of each optical film and the multilayer optical film obtained by regression analysis of the theoretical optical characteristic value group of the multilayer optical film in which the combination of film thicknesses of each optical film is comprehensively allocated within a predetermined range. Preparing a regression equation representing a relationship with a theoretical optical characteristic value;
A step of preparing a model equation representing a relationship between a change amount of manufacturing parameters used for forming each optical film and a change amount of the film thickness of the optical film in the film forming apparatus.
Providing a substrate having a major surface;
A step of sequentially forming a plurality of optical films on the main surface of the substrate to form a multilayer optical film.
A step of measuring optical characteristic values at a plurality of positions in the width direction of the formed multilayer optical film and obtaining actual measurement values thereof.
A step of determining whether or not measured values at a plurality of positions in the width direction are within a predetermined management range based on the target value of the optical characteristic value of the multilayer optical film.
・ If the measured values at multiple locations in the width direction are not within the control range, the measured values at multiple locations in the width direction are applied to the regression equation, and the estimated thickness deviation from the reference thickness for each optical film is calculated in the width direction. Step for calculating a plurality of locations.
-Estimated film thickness deviations at multiple locations in the width direction are applied to the model formula, and manufacturing parameters at multiple locations in the width direction necessary to bring the thickness deviations at multiple locations in the width direction of each optical film close to 0 respectively. Calculating the adjustment amount.
A step of changing the manufacturing parameter by dividing it into a plurality of locations in the width direction based on the adjustment amount.

  (8) In the method for producing a multilayer optical film of the present invention, the production parameter of each optical film is divided into a plurality of positions in the width direction and changed, so that one optical film having a changed thickness with a certain time lag is obtained. In the case of increasing each time, the difference between the predicted value in the width direction of the characteristic value calculated using the regression equation corresponding to the optical film whose thickness has changed and the measured value in the width direction is Including the step of confirming that it is within the calculated expected range.

  (9) In the method for producing a multilayer optical film of the present invention, the substrate is any one of a polymer film, a glass film, a glass plate, a plastic plate, a metal coil, and a metal plate.

  (10) In the method for producing a multilayer optical film of the present invention, the film forming apparatus is any one of a sputtering apparatus, a vapor deposition apparatus, and a CVD apparatus.

  (11) In the method for producing a multilayer optical film of the present invention, the multilayer optical film is any one of a transparent conductive film, a photocatalyst film, a gas barrier film, and a light interference film. Examples of the optical interference film include an antireflection film and an increased reflection film.

[Multi-layer optical film sputtering equipment]
(12) The multilayer optical film sputtering apparatus of the present invention is an apparatus for forming a multilayer optical film on a long film and includes the following.
・ Vacuum tank.
A sputtering gas supply device that supplies sputtering gas to the vacuum chamber.
A film forming roll that is provided in a vacuum chamber and rotates around its central axis.
A plurality of targets facing the film forming roll.
• Multiple power supplies that apply voltage to multiple targets.
A spectral reflectometer that measures the reflection spectrum of a multilayer optical film at multiple locations in the width direction.
An analyzer that estimates the film thickness deviation of each optical film constituting the multilayer optical film using the multilayer optical film thickness control method described above.
A control device that changes manufacturing parameters of each optical film so that film thickness deviations at a plurality of positions in the width direction of each optical film approach zero based on the estimation of the analysis device.

  (13) The multilayer optical film sputtering apparatus of the present invention includes a reactive gas supply device that supplies a reactive gas divided into a plurality of locations in the width direction in a vacuum chamber.

  (14) The multilayer optical film sputtering apparatus of the present invention includes a film supply mechanism for supplying a long film and a film storage mechanism for storing the long film.

  (15) The multilayer optical film sputtering apparatus of the present invention includes a measuring device for plasma emission intensity, and the controller controls the plasma emission intensity by dividing it into a plurality of positions in the width direction.

  When a multilayer optical film is formed according to the present invention, the film thickness in the length direction of the base material (traveling direction of the base material) and the width direction (direction perpendicular to the traveling direction) is set as a target value for each optical film. A film thickness control method that can be brought close to is realized. Furthermore, a multilayer optical film manufacturing method using the control method and a sputtering apparatus using the control method have been realized.

Schematic diagram of multilayer optical film Schematic diagram of multilayer optical film deposition system Flow chart 1 of multilayer optical film thickness control method Example of manufacturing parameters and optical film thickness graph Flowchart 2 of multilayer optical film thickness control method Overall configuration diagram of multilayer optical film sputtering system Diagram of the part related to the division process in the width direction of the multilayer optical film sputtering system

[Multilayer optical film]
FIG. 1 schematically shows an example of a multilayer optical film to which the present invention is applied. Although the number of layers of the multilayer optical film 6 is not limited, FIG. 1 shows a case of five layers. FIG. 1A shows a base material 7 on which a multilayer optical film 6 is laminated. Examples of the material of the substrate 7 include a glass plate, a glass film, a plastic plate, a polymer (plastic) film, a metal coil, and a metal plate. The material, thickness, shape (such as a sheet or a long film) of the substrate 7 are not limited.

  FIG. 1B shows a state in which the first optical film 1 is formed on the base material 7. Examples of the first optical film 1 include a transparent conductive film, a photocatalyst film, a gas barrier film, and a light interference film. Examples of the method for forming the first optical film 1 include sputtering, vapor deposition, and CVD.

  FIG. 1C shows a state in which the second optical film 2 is formed on the first optical film 1. FIG. 1D shows a state in which the third optical film 3 is formed on the second optical film 2. FIG. 1E shows a state in which the fourth optical film 4 is formed on the third optical film 3. FIG. 1F shows a state in which the fifth optical film 5 is formed on the fourth optical film 4. The materials, functions, thicknesses, film forming methods, and the like of the first optical film 1 to the fifth optical film 5 can be appropriately changed according to the use of the multilayer optical film 6 and the like.

  FIG. 1G is a plan view of the multilayer optical film 6 and the substrate 7. The horizontal direction in the figure is the length direction (MD: Machine Direction) (travel direction of the base material 7), and the vertical direction is the width direction (TD: Transverse Direction) (direction orthogonal to the travel direction). The film thicknesses of the optical films 1 to 5 constituting the multilayer optical film 6 vary not only in the length direction but also in the width (TD) direction. According to the multilayer film thickness control method of the present invention, the width Variations in the (TD) direction can also be reduced.

  FIG. 2 is a schematic diagram of an example of a film forming apparatus for the multilayer optical film 6. The base material 7 is sequentially conveyed through the five film forming chambers 41 to 45. The first optical film 1 is formed in the film formation chamber 41, the second optical film 2 is formed in the film formation chamber 42, and the third optical film 3 is formed in the film formation chamber 43. The fourth optical film 4 is formed in the chamber 44, and the fifth optical film 5 is formed in the film formation chamber 45. It is desirable that the film forming chamber 41 to the film forming chamber 45 as a whole be contained in one vacuum chamber 40 so that foreign matter or the like does not enter between the optical films.

  When a multilayer optical film is formed, it is practically difficult to completely match the film thickness of each optical film with the target film thickness (hereinafter referred to as “reference film thickness”). Therefore, it is inevitable that a difference between the actual film thickness and the reference film thickness (hereinafter referred to as “film thickness deviation”) occurs to some extent. Further, the film thickness deviation also occurs in the width direction of each optical film.

  As a result of the actual film thickness being different from the reference film thickness, the optical characteristic value of the actual multilayer optical film is slightly different from the target optical characteristic value (hereinafter referred to as “reference optical characteristic value”). Therefore, a management range is determined for the optical characteristic values of the multilayer optical film. In the multilayer optical film thickness control method of the present invention, the thickness of each optical film may be controlled so as to fall within the allowable range of the film thickness manipulation amount that can be derived from the management range of the optical characteristic values of the multilayer optical film. In addition, it is possible to control the variation of the film thickness of each optical film within the error range as much as possible.

  Here, the “error range” has the following meaning. For example, in the case of a sputtering apparatus described later, the thickness of the optical film is affected by, for example, the gas flow rate. However, even if the setting of the gas flow meter is kept constant, the actual gas flow rate varies in the vicinity of the set value. The film thickness of the optical film varies corresponding to the variation of the gas flow rate. Such film thickness fluctuations include not only the gas flow rate, but also a number of manufacturing parameters such as cathode voltage, target remaining amount, distance between film forming roll and target, film forming roll rotation speed, film substrate running speed, etc. Caused by. The error range means a range of fluctuations in film thickness that cannot be avoided even if the manufacturing parameters are set to be constant. Variations in film thickness due to these causes have been investigated for each film forming apparatus, and are regarded as errors inherent to the film forming apparatus.

[Multilayer optical film thickness control method]
An example of the multilayer optical film thickness control method will be described with reference to the flowchart of FIG. In this example, the multilayer optical film is an n-layer (2 ≦ n) optical film (optical film 1 to optical film n). The control method of the multilayer optical film of this example includes the following steps. The next steps (1) to (4) correspond to the “prepare regression equation” step in the flowchart.

  (1) Theoretical optical characteristic values (reference optical characteristic values) of the multilayer optical film when the optical films 1 to n are the reference film thicknesses ds1 to dsn are calculated.

  (2) Theoretical optical characteristic value groups X1 to Xj of the multilayer optical film when the film thicknesses of the optical films 1 to n are changed from the reference film thickness ds1 to dsn by a predetermined amount Δd1 to Δdn comprehensively. calculate. The magnitudes of the predetermined amounts Δd1 to Δdn are determined in consideration of the magnitude of the influence of the deviation of the film thickness of each optical film on the optical characteristic value. Therefore, the predetermined amounts Δd1 to Δdn are not necessarily the same value, and are not necessarily the same rate of change with respect to the reference film thicknesses ds1 to dsn.

  (3) The regression coefficients and error terms of the predetermined amounts Δd1 to Δdn and the optical characteristic values X1 to Xj are obtained. The optical characteristic values X1 to Xj are arbitrary, but are, for example, brightness Y, color coordinate a *, and color coordinate b *. In this case, the optical characteristic value is j = 3, and X1 = lightness Y, X2 = color coordinate a *, and X3 = color coordinate b *.

(4) Optical characteristic values X1 to Xj
(Δd1), (Δd1) ² ,..., (Δd1) ^k multiplied by a regression coefficient, S1,
(Δd2), (Δd2) ² ,..., (Δd2) ^k multiplied by a regression coefficient, S2,
Similarly,
Sum of terms obtained by multiplying each of (Δdn), (Δdn) ² ,..., (Δdn) ^{k by} a regression coefficient Sn
The k-th order regression equation of the optical characteristic values X1 to Xj is created by expressing the sum of (S1 + S2 +... + Sn) + error term. The order k is set to the minimum necessary order in consideration of the results of regression analysis when k = 1, 2, 3.

  Through the above steps, a regression equation representing the relationship between the film thickness of each optical film and the theoretical optical characteristic value of the multilayer optical film is prepared. The next step (5) corresponds to the “preparation of model formula” step in the flowchart.

  (5) For a predetermined film forming apparatus, a model equation representing the relationship between the change amount of the manufacturing parameter used for forming each optical film and the change amount of the film thickness of the optical film is prepared. FIG. 4 shows an example of a graph of manufacturing parameters and optical film thickness. The X axis is a manufacturing parameter, for example, plasma emission intensity. The Y axis is the film thickness of the optical film. Circles are measured values, and straight lines are straight lines connecting the measured values. The straight line connecting the measured values is obtained by, for example, the least square method. From this graph, the relationship Y = aX + b (a and b are constants) is obtained. This is an example of a model formula that represents the relationship between the change amount of the manufacturing parameter and the change amount of the film thickness of the optical film.

  The relationship between the change amount of the manufacturing parameter and the change amount of the film thickness of the optical film is not necessarily a simple linear expression but may be a complicated polynomial. Alternatively, it is difficult to express by a formula, and the relationship between the change amount of the manufacturing parameter and the change amount of the film thickness of the optical film is expressed by a numerical table, and the relationship may be calculated using an interpolation method if necessary. . In this specification, these are collectively referred to as a “model formula”. In the flowchart, the steps “preparing regression equation” and “preparing model equation” are collectively referred to as “preparation step”. Film formation starts from here.

  (6) Measured values Xr1 to Xrj (r is the meaning of real) of optical characteristic values at a plurality of locations in the width direction of the formed multilayer optical film are obtained.

  (7) It is determined whether or not the actual measurement values Xr1 to Xrj at a plurality of locations in the width direction of the optical characteristic values are within the management range. If the measured values Xr1 to Xrj at a plurality of positions in the width direction are within the control range, the film formation is continued.

  (8) If the measured values Xr1 to Xrj of the optical characteristic values at a plurality of positions in the width direction are out of the management range, the measured values Xr1 to Xrj at the plurality of positions in the width direction are applied to the regression equation, and the optical films 1 to n Estimated film thickness deviation amounts Rd1 to Rdn at a plurality of locations in the width direction are estimated.

  (9) Using a model formula (for example, Y = aX + b), manufacture a plurality of portions in the width direction necessary to bring the film thickness deviation amounts Rd1 to Rdn in the plurality of portions in the width direction of each optical film close to 0, respectively. Calculate the parameter adjustment amount.

  (10) Based on the calculated adjustment amount of the manufacturing parameter, the manufacturing parameter is changed by dividing into a plurality of locations in the width direction. After changing the manufacturing parameter, the process returns to the above (6), and the monitoring of the optical characteristic value is continued.

  When an n-layer multilayer optical film is formed by the film forming method shown in FIG. 2, the following phenomenon may occur. When the manufacturing parameters of the optical film 1 to the optical film n are changed, first, actual measured values Xr1 to Xrj of the multilayer optical film in which only the film thickness of the optical film n is changed are obtained. The film does not change in thickness). Next, measured values Xr1 to Xrj of the optical characteristic values of the multilayer optical film in which the film thicknesses of the optical film n and the optical film n-1 are changed are obtained with a certain time lag (at this time, the optical film n and the optical film n− The film thickness of the optical film other than 1 is not changed). In the same manner, the number of optical films whose film thickness has changed is increased layer by layer, and the corresponding measured values Xr1 to Xrj of the multilayer optical film are obtained. Finally, actual measurement values of the optical characteristic values of the multilayer optical film in which the film thicknesses of the optical film n, the optical film n-1,..., The optical film 1 (all optical films) are changed are obtained.

  In such a case, the multilayer optical film thickness control method of the present invention includes the following steps shown in the flowchart of FIG. The preparation steps in the flowchart in FIG. 5 are the same as the preparation steps in the flowchart in FIG. Each step before changing the manufacturing parameters is the same as that shown in FIG.

  (1) The measured values Xr1 to Xrj at a plurality of positions in the width direction of the optical characteristic value are obtained for the multilayer optical film in which only the film thickness of the optical film n is changed. It is confirmed that the difference between the predicted values X1 to Xj calculated using the sum Sn of the regression equations and the actual measurement values Xr1 to Xrj at a plurality of locations in the width direction is within an assumed range calculated by the regression equation. Thereby, it can be confirmed that the change of the manufacturing parameters of the optical film n was appropriate.

  If the difference between the predicted values X1 to Xj and the measured values Xr1 to Xrj at multiple locations in the width direction is outside the expected range calculated by the regression equation, the estimated film thickness deviations at multiple locations in the width direction are calculated using the regression equation. The estimation is performed, the adjustment amounts of the manufacturing parameters at a plurality of positions in the width direction are calculated using the model formula, and the manufacturing parameters are divided and changed at a plurality of positions in the width direction.

  Here, the “assumed range calculated by the regression equation” is an optical characteristic due to an error that normally occurs in the film forming apparatus used, with the predicted values X1 to Xj calculated using the sum Sn of the regression equation as the central value. This refers to the range of optical characteristic values obtained by adding or subtracting the value variation to the above-mentioned center value. In addition, the following “assumed range calculated by the regression equation” is changed in accordance with “sum of regression equations”. For example, in the following (2), the sum of the regression equations is Sn + S (n-1).

  (2) The measured values Xr1 to Xrj at a plurality of positions in the width direction of the optical characteristic value are obtained for the multilayer optical film in which the film thicknesses of the optical film n and the optical film (n-1) are changed, and the sum of the regression equations Sn + S ( It is confirmed that the difference between the predicted values X1 to Xj calculated using n-1) and the actual measured values Xr1 to Xrj at a plurality of positions in the width direction is within the assumed range calculated by the regression equation. Thereby, it can be confirmed that the change of the manufacturing parameters of the optical film n-1 was appropriate.

  If the difference between the predicted values X1 to Xj and the measured values Xr1 to Xrj at multiple locations in the width direction is outside the expected range calculated by the regression equation, the estimated film thickness deviations at multiple locations in the width direction are calculated using the regression equation. The estimation is performed, the adjustment amounts of the manufacturing parameters at a plurality of positions in the width direction are calculated using the model formula, and the manufacturing parameters are divided and changed at a plurality of positions in the width direction.

  (3) In the same manner, confirm that the change of the manufacturing parameters of the optical film is appropriate for each optical film. Finally, optical film n, optical film (n-1), ..., measured values at multiple locations in the width direction of the optical characteristic values for the multilayer optical film whose optical film 1 (all optical films) has changed thickness Xr1 to Xrj are obtained, and the difference between the predicted values X1 to Xj calculated using the sum of the regression equations Sn + S (n-1) + ... + S1 and the measured values Xr1 to Xrj at multiple locations in the width direction is Confirm that it is within the calculated expected range. Accordingly, it can be confirmed that the manufacturing parameter of the optical film 1 has been appropriately changed. If the manufacturing parameters of all the optical films are appropriately changed, the film formation is continued.

  If the difference between the predicted values X1 to Xj and the measured values Xr1 to Xrj at multiple locations in the width direction is outside the expected range calculated by the regression equation, the estimated film thickness deviations at multiple locations in the width direction are calculated using the regression equation. The amount of adjustment of manufacturing parameters at a plurality of locations in the width direction is calculated using a model formula, and the manufacturing parameters are changed by dividing into a plurality of locations in the width direction.

  According to the multilayer optical film thickness control method of the flowchart of FIG. 5, it is possible to check whether or not the change of the manufacturing parameters at a plurality of positions in the width direction is appropriate every time the optical film changes. The feedback on whether or not the adjustment amount is appropriate becomes faster. This is a great advantage for mass production lines.

  In the multilayer optical film thickness control method of the present invention, the management range used for film formation can be made narrower than the original management range derived from the standard of optical characteristics. In this case, when the actual measured value of the optical characteristic value shows a tendency to move away from the target value even within the original management range, the actual measured value can be controlled to return to the target value.

  In the multilayer optical film thickness control method of the present invention, the optical property value of the multilayer optical film can be set to the reference optical by narrowing the management range used for film formation from the original management range derived from the optical property standard. A multilayer optical film distributed in a narrow range centering on the characteristic value can be obtained. That is, the process capability can be increased by using the multilayer optical film thickness control method of the present invention. As a result, a high-quality multilayer optical film with little variation in characteristics can be obtained.

[Method for producing multilayer optical film]
The multilayer optical film manufacturing method of the present invention was obtained by regression analysis of theoretical optical property value groups of multilayer optical films in which combinations of film thicknesses of a plurality of optical films were comprehensively allocated within a predetermined range. And a step of preparing a regression equation representing the relationship between the film thickness of each optical film and the optical characteristic value of the multilayer optical film. The contents of the step of preparing the above regression equation are not repeated because they are described in [Multilayer Optical Film Thickness Control Method]. This step is a preparatory step before film formation. If the materials of the base material and the multilayer optical film are not changed, they may be performed once before the film formation is started.

  The method for producing a multilayer optical film of the present invention is a step of preparing a model equation representing a relationship between a change amount of a production parameter used for film formation of each optical film and a change amount of the film thickness of the optical film for a predetermined film formation apparatus. including. A model expression of the relationship between the manufacturing parameter change amount and the optical film thickness change amount is obtained experimentally as shown in FIG. For example, in the case of a sputtering apparatus, for example, the relationship between plasma emission intensity and the film thickness of each optical film is experimentally determined. This step is also a preparation step before film formation. If the film forming apparatus, the fixed film forming conditions (for example, the temperature of the film forming roll, the traveling speed of the base material), and the materials of the base material and the multilayer optical film are not changed, It may be performed once before the start of film formation.

  Thereafter, a multilayer optical film is formed. This includes providing a substrate having a major surface. Here, examples of the material of the substrate include a polymer film, a glass film, a glass plate, a plastic plate, a metal coil, and a metal plate. The material, thickness, shape (such as a sheet or a long film) of the substrate is not limited.

  The method for producing a multilayer optical film of the present invention includes a step of sequentially forming a plurality of optical films on the main surface of the substrate to form the multilayer optical film. Here, examples of the multilayer optical film include a transparent conductive film, a photocatalyst film, a gas barrier film, and a light interference film. Examples of film forming methods include sputtering, vapor deposition, and CVD. The material, type, thickness, film forming method, and the like of the multilayer optical film are not limited.

  The method for producing a multilayer optical film of the present invention includes a step of measuring optical characteristic values at a plurality of locations in the width direction of the formed multilayer optical film and obtaining actual measurement values at the plurality of locations in the width direction. Further, the method includes a step of determining whether or not the actual measurement values at a plurality of locations in the width direction are within a predetermined management range based on the target value of the target optical characteristic value of the multilayer optical film. Further, when the measured values at a plurality of positions in the width direction are not within the management range, the measured values are applied to a regression equation to calculate an estimated film thickness deviation amount from the reference film thickness of each optical film for the plurality of positions in the width direction. including.

  Further, the estimated film thickness deviation amounts at a plurality of positions in the width direction are applied to the model formula, and the manufacturing parameters at the plurality of positions in the width direction necessary to bring the film thickness deviation amounts at the plurality of positions in the width direction of each optical film close to 0 respectively. A step of calculating the adjustment amount. Further, the method includes a step of dividing and changing the manufacturing parameter at a plurality of positions in the width direction based on the adjustment amount. Details regarding the film thickness control of the optical film have been described in the section [Method of film thickness control of multilayer optical film] and will not be repeated.

[Multi-layer optical film sputtering equipment]
FIG. 6 is an overall configuration diagram of an example of the sputtering apparatus of the present invention. The sputtering apparatus 10 is an apparatus for forming a multilayer optical film on the long film 11 and is controlled using the multilayer optical film thickness control method of the present invention. In FIG. 6, thin lines indicate electrical wiring or gas piping, and broken lines indicate signal lines such as spectral reflectance (reflection spectrum), plasma emission intensity, cathode voltage, and gas flow rate. FIG. 6 is a diagram in which a multilayer optical film is being formed on the long film 11.

  A sputtering apparatus 10 includes a supply roll 13 for a long film 11, a guide roll 14 for guiding the running of the long film 11, a cylindrical film forming roll 15 for winding the long film 11 slightly less than one turn in a vacuum chamber 12, A storage roll 16 for storing the long film 11 is provided. The film forming roll 15 is also called a can roll. The film forming roll 15 rotates around its central axis. During film formation, the film forming roll 15 rotates, and the long film 11 travels in synchronization with the film forming roll 15 rotating.

  A target 17 is installed around the film forming roll 15 so as to face the film forming roll 15. The target 17 is disposed at a predetermined distance from the film forming roll 15. The central axis of the film forming roll 15 and the target 17 are parallel. Although there are five targets 17 in FIG. 6, the number of targets 17 is not limited. On the outside of the target 17 (on the opposite side of the film forming roll 15), a cathode 18 is installed in close contact with the target 17. The target 17 and the cathode 18 are mechanically and electrically coupled.

  A sputtering power source 20 is connected to each cathode 18. Since the cathode 18 and the target 17 are at the same potential, the sputtering power source 20 is connected to the target 17. It is not necessary when the sputtering power source 20 is direct current (DC, pulse DC) or alternating current (MF-AC) in the MF (Middle Frequency) region, but in the case of alternating current (RF-AC) in the RF (Radio Frequency) region, A matching box (not shown) is inserted between the cathode 18 and the sputter power supply 20 to adjust the impedance of the target 17 viewed from the sputter power supply 20 side, and the reflected power (reactive power) from the target 17 is minimized.

  The type, pressure, and supply amount of sputtering gas or reactive gas required for each target 17 may be different. Therefore, the vacuum chamber 12 is divided by the partition wall 24 to be divided into the division tanks 25 so as to separate the targets 17. A pipe 27 is connected to each division tank 25 from a gas supply device 26 (GAS), and a reactive gas (for example, oxygen) is supplied at a predetermined flow rate. The flow rate of the reactive gas is controlled by a flow meter 28 (mass flow controller: MFC).

  Although not shown, a plurality of targets 17 may be installed in one division tank 25. In this case, different materials can be sputtered in the same gas atmosphere. In addition, when the sputtering speed of the material in the dividing tank 25 is slower than the sputtering speed of the material in the other dividing tank 25, a plurality of targets of the same material are used in the dividing tank 25 in order to maintain the traveling speed of the long film 11. 17 can be used for sputtering.

  A sputtered film adheres to the surface of the long film 11 that travels in synchronization with the rotation of the film forming roll 15 at a position facing the target 17 to form an optical film. In FIG. 6, the number of film forming rolls 15 is one, but there may be two or more film forming rolls 15 (not shown).

  As the long film 11, a transparent film made of a homopolymer or a copolymer such as polyethylene terephthalate, polybutylene terephthalate, polyamide, polyvinyl chloride, polycarbonate, polystyrene, polypropylene, or polyethylene is generally used. The long film 11 may be a single layer film or a laminated film such as a polarizing film having an optical function. Although it does not specifically limit as a laminated | multilayer film, For example, the laminated body which contains a polarizing film further in the polarizing plate which contains a polarizing layer and at least 1 layer of protective layer, and the said polarizing plate is mentioned. Although the thickness of the long film 11 is not limited, Usually, it is about 6 micrometers-250 micrometers.

  In the sputtering apparatus 10, a sputtering voltage is applied between the film-forming roll 15 and the target 17 in a sputtering gas such as argon gas, with the film-forming roll 15 at an anode potential and the target 17 as a cathode potential. As a result, sputtering gas plasma is generated between the long film 11 and the target 17. Sputtering gas ions in the plasma are electrically accelerated and collide with the target 17 to strike out the constituent material of the target 17. The constituent material of the target 17 struck out is deposited on the long film 11 and becomes a sputtered film.

  In the sputtering apparatus 10, the long film 11 before film formation is continuously pulled out from the supply roll 13, wound slightly less than one turn around the film formation roll 15, and the film formation roll 15 is rotated at a constant speed to form the long film 11. The long film 11 is wound around the storage roll 16 by being fed in synchronization with the film roll 15.

  In the sputtering apparatus 10, since there are five targets 17, the first optical film, the second optical film, the third optical film, the fourth optical film, and the fifth optical film are long from the side close to the supply roll 13. Films are sequentially formed on the film 11. Therefore, there is a time lag between the formation of each optical film. The time lag for forming adjacent optical films is about 1/5 of the time required for one rotation of the film forming roll 15.

  The sputtering apparatus 10 includes a spectral reflectometer 29 that measures the reflection spectrum of the multilayer optical film formed on the long film 11. Although not shown, when there are two or more film forming rolls 15, a spectral reflectometer 29 may be installed between the film forming rolls 15.

  The multilayer optical film manufactured by the sputtering apparatus 10 has five layers. From the reflection spectrum of the multilayer optical film measured by the spectral reflectometer 29, the analyzer 30 measures the optical characteristic values, for example, lightness Y, color coordinates a *, and color coordinates b * at a plurality of positions in the width direction. Desired. The lightness Y, the color coordinate a *, and the color coordinate b * are examples, and other color system coordinate systems are also used.

  The analyzer 30 stores regression equations of optical characteristic values Y, a *, and b *. In the analyzer 30, the measured values of the optical characteristic values Y, a *, and b * in the width direction are applied to the regression equation, and the film thickness deviations in the width directions of the first to fifth optical films are calculated. Rd1 to Rd5 are estimated. The estimated film thickness deviations Rd1 to Rd5 at a plurality of locations in the width direction are transferred from the analysis device 30 to the control device 31.

  The control device 31 includes a change amount of manufacturing parameters (for example, plasma emission intensity) of the first optical film to the fifth optical film experimentally obtained for the sputtering apparatus 10, and the first optical film to the fifth optical film. A model formula representing the relationship of the amount of change in film thickness is stored. The control device 31 changes the manufacturing parameters at a plurality of positions in the width direction when forming the first optical film to the fifth optical film so that the film thickness deviations Rd1 to Rd5 at the plurality of positions in the width direction approach zero. The

  As shown in FIG. 7, in the sputtering apparatus 10, a reactive gas is supplied from gas ejection pipes 34 divided into, for example, four pieces (generally, a plurality) in the width direction of the long film 11. There is no limit to the number of gas supply divisions. The gas supply amount of each gas ejection pipe 34 is individually controlled by the flow meter 28 (MFC mass flow controller) for each gas ejection pipe 34.

  The sputtering apparatus 10 includes a spectral reflectometer 29 that measures reflection spectra at four locations (generally a plurality of locations) in the width direction of a multilayer optical film formed on the main surface of the long film 11. The reflection spectrum measured at four locations corresponds to the gas supply being divided into four parts. Thus, it is desirable that the number of gas supply divisions corresponds to the number of measurement points of the reflection spectrum.

  As shown in FIG. 7, the spectral reflectometer 29 may be provided in four units (generally a plurality of units) so as to correspond to four units (generally a plurality of units) in the width direction, although not shown. Alternatively, the reflected light may be taken into one spectral reflectometer 29 from four places (generally a plurality of places) in the width direction by an optical fiber or the like, and sequentially measured in a time division manner.

  Based on the reflection spectrum of the multilayer optical film at four locations (generally a plurality of locations) in the width direction measured by the spectral reflectometer 29, actual measurement at four locations (typically a plurality of locations) in the width direction is performed by the analyzer 30. Characteristic values, for example Y, a *, b *, are calculated. The analyzer 30 stores regression equations of characteristic values Y, a *, and b *. In the analysis device 30, the measured characteristic values at four positions (generally, a plurality of positions) in the width direction of the characteristic values Y, a *, and b * are applied to the regression equation, and the optical films 1 to 5 are measured in the width direction. The film thickness deviation at four locations (generally a plurality of locations) is estimated. The estimated film thickness deviation data at four locations (generally a plurality of locations) in the width direction are transferred from the analysis device 30 to the control device 31.

  The control device 31 has a model equation indicating the relationship between manufacturing parameters (for example, plasma emission intensity of reactive gas) when forming the optical films 1 to 5 and the film thicknesses of the optical films 1 to 5. It is remembered. By the control device 31, four positions in the width direction (general) when the optical films 1 to 5 are formed so that the film thickness deviations at four positions (generally a plurality of positions) in the width direction approach 0 each. In other words, manufacturing parameters at a plurality of locations are changed.

  In the sputtering apparatus 10 of the present invention, a multilayer optical film is formed on the long film 11 as follows. The long film 11 before film formation is continuously pulled out from the supply roll 13, wound slightly around the film formation roll 15, and the film formation roll 15 is rotated at a constant speed to synchronize the long film 11 with the film formation roll 15. The long film 11 is wound around the storage roll 16.

  A sputtered film corresponding to the material of each target 17 is formed on the long film 11 wound around the film forming roll 15 at a position facing each target 17. In the sputtering apparatus 10 of FIG. 6, since there are five targets 17, the optical films 1 to 5 are sequentially formed and stacked on the long film 11 from the side close to the supply roll 13. Therefore, there is a time lag between the formation of each optical film. The time lag for forming adjacent optical films is about 1/5 of the time for which the film forming roll 15 rotates once.

  The plasma emission intensity is measured by the plasma emission intensity measuring device 32 by dividing the target 17 into a plurality of locations in the width direction. By dividing and changing the target value of the plasma emission intensity at a plurality of positions in the width direction, the film thickness of the optical film is divided and changed at a plurality of positions in the width direction. The flow rate of the reactive gas is controlled for each target using a flow meter 28 (MFC) and divided into a plurality of locations in the width direction.

  When a plurality of optical films are successively and sequentially formed on the long film 11 using the sputtering apparatus 10, the following phenomenon occurs. In the sputtering apparatus 10 of FIG. 6, five targets 17 are arranged around the film forming roll 15 in order to laminate the five layers of optical films on the long film 11, and the long film 11 goes around the film forming roll 15. In the meantime, five optical films are sequentially formed.

  In this case, even if the manufacturing parameters for forming the first optical film to the fifth optical film are changed at the same time, the multilayer optical film in which only the thickness of the fifth optical film (the last optical film) is changed. Is obtained. At this time, the film thicknesses of the fourth optical film to the first optical film have not changed yet.

  Next, with a certain time lag (approximately 1/5 of the time required for one rotation of the film forming roll), a multilayer optical film in which the film thicknesses of the fifth optical film and the fourth optical film are changed is obtained. At this time, the film thicknesses of the third optical film to the first optical film have not changed yet.

  Similarly, the optical films whose thickness has changed are increased by one layer, and at the same time, the optical films whose thickness has not changed are decreased by one layer. Finally, after the film-forming roll 15 has rotated approximately once, a multilayer optical film in which the film thicknesses of the fifth optical film to the first optical film (all optical films) have been changed is obtained.

  That is, with a certain time lag (approximately 1/5 of the time for which the film-forming roll 15 makes one rotation), the number of optical films whose thickness changes is increased by one layer, and the number of optical films whose thickness does not change is one layer. Decreases by increments. Therefore, a considerable time lag (time for the film forming roll 15 to rotate approximately once) is required until a multilayer optical film having a film thickness changed in all the optical films is obtained.

  In such a case, according to the film thickness control method shown in the flowchart of FIG. 5, the measured characteristic values at a plurality of positions in the width direction are obtained every time the optical film whose film thickness has changed is increased layer by layer, By using a method for judging the suitability of changes made by dividing into a plurality of locations one layer at a time, it is possible to speed up the feedback of the suitability of the adjustment amounts of the manufacturing parameters at a plurality of locations in the width direction.

  In the sputtering apparatus 10 of the present invention, as described above, the film thickness control method of the present invention is automatically executed without requiring human intervention. Thereby, the automatic operation of the film forming process of the multilayer optical film can be performed in a state where the optical characteristic value is automatically maintained in the management range. If the film thickness control method of the present invention is used, the same automatic operation is not limited to the sputtering apparatus, and various film forming apparatuses such as a vacuum deposition apparatus and a CVD apparatus can be used.

  The multilayer optical film thickness control method of the present invention and the multilayer optical film manufacturing method of the present invention include a multilayer ITO (Indium Tin Oxide Indium Tin Oxide) film, a multilayer photocatalyst film, a multilayer gas barrier (blocking) film, and a multilayer antireflection film. (AR: Anti Reflection) It can be applied to film formation. The multilayer optical film thickness control method of the present invention can be applied to a film forming method using a sputtering method, a vacuum deposition method, a CVD method, or the like. The sputtering apparatus of the present invention is used for forming a multilayer optical film.

DESCRIPTION OF SYMBOLS 1 1st optical film 2 2nd optical film 3 3rd optical film 4 4th optical film 5 5th optical film 6 Multilayer optical film 7 Base material 10 Sputtering device 11 Long film 12 Vacuum tank 13 Supply roll 14 Guide roll 15 Composition Film roll 16 Storage roll 17 Target 18 Cathode 20 Sputtering power source 24 Partition 25 Divided tank 26 Gas supply device 27 Pipe 28 Flow meter 29 Spectral reflectometer 30 Analyzer 31 Control device 32 Plasma emission intensity meter 33 Cathode voltmeter 40 Vacuum chamber 41-45 Deposition chamber

Claims (13)

A film thickness control method for controlling the film thickness of each of the optical films when a multilayer optical film formed by laminating a plurality of optical films is formed using a film forming apparatus,
The film thickness of each optical film and the multilayer obtained by regression analysis of theoretical optical characteristic value groups of the multilayer optical film in which combinations of film thicknesses of the optical films are allotted within a predetermined range. Preparing a regression equation representing the relationship with the theoretical optical property value of the optical film;
For the film forming apparatus, preparing a model equation representing the relationship between the amount of change in manufacturing parameters used for film formation of each of the optical films and the amount of change in film thickness of the optical films;
Measuring optical property values at a plurality of locations in the width direction of the multilayer optical film thus formed, and obtaining the actual measurement values;
Applying the actual measurement value to the regression equation to calculate an estimated film thickness deviation amount from a reference film thickness of each of the optical films for a plurality of locations in the width direction;
Applying the estimated film thickness deviation amount to the model formula, and calculating adjustment amounts of the manufacturing parameters at a plurality of positions in the width direction necessary to bring the film thickness deviation amounts of the optical films close to 0, respectively. ,
A method of controlling the film thickness of the multilayer optical film, comprising: dividing the manufacturing parameter into a plurality of locations in the width direction based on the adjustment amount.   2. The method of controlling a film thickness of a multilayer optical film according to claim 1, wherein the optical characteristic value of the multilayer optical film is the brightness and / or color coordinates of reflected light from the multilayer optical film.   The multilayer optical film thickness control method according to claim 1, wherein a sputtering method is used when forming the multilayer optical film.   The method of controlling a film thickness of a multilayer optical film according to claim 3, wherein the plasma emission intensity is used as a manufacturing parameter to be changed when the multilayer optical film is formed.   The multilayer optical film thickness control method according to claim 1, wherein the multilayer optical film is any one of a transparent conductive film, a photocatalyst film, a gas barrier film, and a light interference film. A method for producing a multilayer optical film, wherein a multilayer optical film formed by laminating a plurality of optical films is formed using a film forming apparatus,
The film thickness of each optical film and the multilayer optics obtained by regression analysis of theoretical optical characteristic value groups of the multilayer optical film in which the combinations of film thicknesses of the respective optical films are comprehensively allocated within a predetermined range Preparing a regression equation representing the relationship with the theoretical optical property value of the film;
For the film forming apparatus, preparing a model equation representing the relationship between the amount of change in manufacturing parameters used for film formation of each of the optical films and the amount of change in film thickness of the optical films;
Providing a substrate having a major surface;
Sequentially forming the plurality of optical films on the main surface of the substrate to form a multilayer optical film;
Measuring optical property values at a plurality of locations in the width direction of the multilayer optical film thus formed, and obtaining the actual measurement values;
Determining whether the measured value is within a predetermined management range based on a target value of an optical characteristic value of the multilayer optical film;
If the measured value is not within the management range, applying the measured value to the regression equation and calculating an estimated film thickness deviation amount from a reference film thickness of each of the optical films for a plurality of locations in the width direction;
Applying the estimated film thickness deviation amount to the model formula, and calculating adjustment amounts of the manufacturing parameters at a plurality of positions in the width direction necessary to bring the film thickness deviation amounts of the optical films close to 0, respectively. ,
Dividing the manufacturing parameter into a plurality of locations in the width direction based on the adjustment amount and changing the manufacturing parameter.   The method for producing a multilayer optical film according to claim 6, wherein the substrate is any one of a polymer film, a glass film, a glass plate, a plastic plate, a metal coil, and a metal plate.   The method for producing a multilayer optical film according to claim 6 or 7, wherein the film forming apparatus is any one of a sputtering apparatus, a vapor deposition apparatus, and a CVD apparatus.   The method for producing a multilayer optical film according to claim 6, wherein the multilayer optical film is any one of a transparent conductive film, a photocatalyst film, a gas barrier film, and a light interference film. A multilayer optical film sputtering apparatus for forming a multilayer optical film on a long film,
A vacuum chamber;
A sputtering gas supply device for supplying a sputtering gas to the vacuum chamber;
A film forming roll provided in the vacuum chamber and rotating around its central axis;
A plurality of targets facing the film forming roll;
A plurality of power supplies for applying a voltage to the plurality of targets;
A spectral reflectometer for measuring the reflection spectrum of the multilayer optical film at a plurality of locations in the width direction;
An analyzer for estimating a film thickness deviation of each optical film constituting the multilayer optical film using the multilayer optical film thickness control method according to any one of claims 1 to 5,
A controller for changing manufacturing parameters at a plurality of positions in the width direction of each of the optical films based on the estimation of the analyzer so that the film thickness deviations at a plurality of positions in the width direction of each of the optical films approach zero; Multi-layer optical film sputtering equipment.   The multilayer optical film sputtering apparatus according to claim 10, further comprising a reactive gas supply device that divides and supplies a reactive gas to the vacuum chamber at a plurality of locations in the width direction.   12. The multilayer optical film sputtering apparatus according to claim 10, further comprising a film supply mechanism for supplying the long film and a film storage mechanism for storing the long film.   The multilayer optical film sputtering apparatus according to claim 10, further comprising a measuring device for plasma emission intensity, wherein the control device controls the plasma emission intensity by dividing the plasma emission intensity into a plurality of locations in the width direction.

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