Multilayer optical thin film forming apparatus, method, program, and storage medium

Abstract

To provide a thin film forming apparatus and a thin film forming method capable of automatically selecting an optimum control system from a plurality of control systems in each layer of a multilayer optical thin film, thereby enabling film formation statistically closest to a design while reducing a burden on an operator in the production of the multilayer optical thin film.SOLUTION: The thin film forming apparatus is configured such that when a multilayer optical thin film is formed on a film formation target substrate, a control unit for controlling film formation of a thin film on the film formation target substrate according to a light reception signal obtained by receiving monitor light transmitted through the film formation target substrate performs simulation of film formation of each layer in the multilayer optical thin film before film formation operation of the multilayer optical thin film, the simulation is performed in a plurality of control modes, an optimum control mode is automatically selected from the plurality of control modes for each layer on the basis of the result of the simulation, and the film formation control of each layer of the multilayer optical thin film is executed by the selected optimum control mode.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for forming a multilayer optical thin film, and more particularly to an apparatus and method for forming a thin film, a program, and a storage medium, which employ an optical film thickness control device that can automatically select the optimum control method for each layer. [Background technology]

[0002] BACKGROUND ART Multilayer optical thin films, which have a laminated structure in which a plurality of optical thin films are superimposed on a substrate, are known as optical thin films that are widely used in the field of optical equipment.

[0003] Single wavelength control is known as a method for controlling the deposition of multilayer optical thin films, and several control methods are provided, such as light intensity control, proportional control, TMF control, and TPC control.

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-199084 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-222596 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] However, the multiple control methods described above, such as conventional light intensity control, proportional control, TMF control, and TPC control, have the problem that the optimal control method differs for each layer depending on factors such as the product's film design, monitoring wavelength, the magnitude of optical system noise, and spectrometer resolution.

[0006] That is, when multilayer film formation is controlled using a single control method, such as TMF control, there is a problem in that the average error and standard deviation become large in some layers. As mentioned above, the multiple control methods, such as light intensity control, proportional control, TMF control, and TPC control, have different error averages and standard deviations for each layer depending on complex factors such as the film design, monitoring wavelength, the magnitude of optical system noise, and spectrometer resolution. Therefore, selecting the optimal control method is difficult without skilled knowledge based on extensive experience, and has been difficult for ordinary users of thin film deposition equipment.

[0007] The present invention has been made in consideration of the above-mentioned conventional problems, and aims to provide a thin film forming apparatus, method, program, and storage medium that employs an optical film thickness control device that can reduce the average and standard deviation of errors in each layer when forming a multilayer optical thin film. Another object of the present invention is to provide a thin film forming apparatus, method, program, and storage medium that employs an optical film thickness control device that can reduce the burden on an operator by automatically selecting the optimal control method from multiple control methods for each layer of a multilayer optical thin film. [Means for solving the problem]

[0008] In order to achieve the above object, the thin film forming apparatus of the present invention for forming a multilayer optical thin film on a substrate to be formed has a control unit that controls the formation of a thin film on the substrate to be formed in accordance with a light receiving signal obtained by receiving monitor light that has passed through the substrate to be formed, and is characterized in that the control unit performs a simulation of the formation of each layer in the multilayer optical thin film using a plurality of control modes before the formation operation of the multilayer optical thin film, automatically selects an optimal control mode from the plurality of control modes for each layer based on the results of the simulation, and performs film formation control of each layer of the multilayer optical thin film using the selected optimal control mode.

[0009] Another feature of the present invention is that it comprises a light-projecting unit that projects monitor light onto a substrate to be film-formed, on which a thin multilayer film is formed by depositing a film material supplied from a film-forming material supply unit arranged in a film-forming chamber; a light-receiving unit that receives the monitor light that has passed through the substrate to be film-formed and outputs a light-receiving signal; a temperature measuring unit that measures the substrate temperature during film formation; and a control unit that acquires the light transmittance of the substrate to be film-formed in accordance with the light-receiving signal and controls the formation of the thin film in association with the acquired light transmittance information, wherein the control unit performs a simulation of the formation of each layer of the multilayer optical thin film using a plurality of control modes before the film-forming operation of the multilayer optical thin film, automatically selects an optimal control mode from the plurality of control modes for each layer based on the results of the simulation, and performs film-forming control of each layer of the multilayer optical thin film using the selected optimal control mode.

[0010] Another feature of the present invention is a thin film formation method for forming a multilayer optical thin film on a substrate to be deposited, in a thin film formation apparatus having a control unit that controls the formation of a thin film on the substrate to be deposited in accordance with a received light signal obtained by receiving monitor light that has passed through the substrate to be deposited, the method comprising the steps of: using the control unit to simulate the formation of each layer of the multilayer optical thin film in a plurality of control modes before the deposition operation of the multilayer optical thin film; using the control unit to automatically select an optimal control mode from the plurality of control modes for each layer based on the results of the simulation; and using the control unit to execute deposition control of each layer of the multilayer optical thin film using the selected optimal control mode.

[0011] Another feature of the present invention resides in a thin film forming apparatus for forming a multilayer optical thin film on a substrate to be film-formed, the thin film forming apparatus having a control unit made of a computer that controls the formation of a thin film on the substrate to be film-formed in response to a light-receiving signal obtained by receiving monitor light transmitted through the substrate to be film-formed, the thin film forming apparatus comprising: a program for causing the computer to execute the following steps: a procedure for simulating the formation of each layer of the multilayer optical thin film in a plurality of control modes before the film-forming operation of the multilayer optical thin film; a procedure for automatically selecting an optimum control mode from the plurality of control modes for each layer based on the results of the simulation; and a procedure for controlling the formation of each layer of the multilayer optical thin film by the control unit in the selected optimum control mode. [Effects of the Invention]

[0012] According to the present invention, the optimum control method can be automatically selected from a plurality of control methods for each layer of a multilayer optical thin film, thereby reducing the burden on the operator in the manufacture of a multilayer optical thin film and enabling the formation of a film that is statistically closest to the design. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an ion beam assisted vacuum deposition apparatus, which is a thin film forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram schematically illustrating an example of a film formation target substrate and a multilayer film of thin films formed on the film formation target substrate according to this embodiment. [Figure 3] FIG. 3 is a block diagram of the internal configuration of the control unit 60 shown in FIG. [Figure 4] FIG. 4 is a flow chart of a method for controlling and optimizing the deposition of each layer in a multilayer optical thin film. [Figure 5] FIG. 5 is a diagram showing an example of a control content screen displayed on the display monitor 64 in the method for optimizing film formation control for each layer shown in FIG. [Figure 6]FIG. 6 is a diagram showing an example of a control content screen displayed on the display monitor 64 in the method for optimizing film formation control for each layer shown in FIG. [Figure 7] FIG. 7 is a diagram showing two evaluation function formulas set in the simulation setting in step 103 of FIG. [Figure 8] FIG. 8 is a diagram showing an example of a control content screen displayed on the display monitor 64 in the method for optimizing film formation control for each layer shown in FIG. [Figure 9] FIG. 9 is a diagram showing an example of a control content screen displayed on the display monitor 64 in the method for optimizing film formation control for each layer shown in FIG. [Figure 10] FIG. 10 is a diagram showing an example of a control content screen displayed on the display monitor 64 in the method for optimizing film formation control for each layer shown in FIG. [Figure 11] FIG. 11 is a diagram showing an example of a control content screen displayed on the display monitor 64 in the method for optimizing film formation control for each layer shown in FIG. [Figure 12] FIG. 12 is a diagram showing an example of a control content screen displayed on the display monitor 64 in the method for optimizing film formation control for each layer shown in FIG. [Figure 13] FIG. 13 is a diagram showing an example of film formation control using a fitting function in the film formation process in step 112 of FIG. [Figure 14] FIG. 14 is a diagram showing an example of film formation control using proportional control in the film formation process in step 112 of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] A vacuum film-forming apparatus as a thin film-forming apparatus embodying the present invention and a vacuum film-forming method as a thin film-forming method using the same will be described below with reference to the drawings.

[0015] 1 is a schematic diagram showing the configuration of an ion beam assisted vacuum deposition apparatus, which is a thin film forming apparatus according to the present invention. This vacuum deposition apparatus employs a batch production method. The vacuum deposition apparatus shown in FIG. 1 is merely an example, and any configuration may be used as long as it is a thin film forming apparatus that executes a film formation control program including a film formation control optimization method program for each layer, which will be described later.

[0016] In the vacuum deposition apparatus 1 of this embodiment, for example, an exhaust pipe and a vacuum pump (not shown) are connected to a vacuum chamber 10, which is a film formation chamber, so that the inside can be depressurized to a predetermined pressure. The back pressure in the vacuum chamber 10 during film formation by vacuum deposition is, for example, about 10-2 to 10-5 Pa.

[0017] A first vacuum evaporation source 21 and a second vacuum evaporation source 22 are arranged in the lower interior of the vacuum chamber 10 as a film forming material supply unit 20. A first evaporation material 211 is accommodated inside the first vacuum evaporation source 21, and a second evaporation material 221 is accommodated inside the second vacuum evaporation source 22. The first deposition material 21 is, for example, SiO2, and the second deposition material 23 is, for example, TiO2 or Ta2O5. Each vacuum evaporation source 21, 22 is provided with a heating means such as resistance heating, electron beam heating, laser beam heating, or an electron gun (not shown), and when the evaporation material is heated and vaporized in the vacuum evaporation source, the vapor of the evaporation material is ejected.

[0018] For example, within the vacuum chamber 10, a substrate holder 31 is provided that holds a film-forming target substrate 30, which is an optical substrate such as quartz glass, in the direction in which the vapor of the evaporation material from the first vacuum evaporation source 21 and the second vacuum evaporation source 22 is ejected, with the film-forming surface facing the film-forming material supply section 20. For example, the substrate holder 31 is supported by a holder support 32 from above the vacuum chamber 10 .

[0019] Although Figure 1 shows an example in which two vacuum evaporation sources are provided to form a multilayer film of two types of thin films, various embodiments are possible, such as providing three vacuum evaporation sources to form a multilayer film of three types of thin films. When three vacuum evaporation sources are used, for example, the first evaporation material is SiO2, the second evaporation material is Si3N4, and the third evaporation material is a-SiN:H.

[0020] 2(a) and 2(b) are diagrams schematically illustrating an example of a film-formation target substrate 30 according to this embodiment and a multilayer film of thin films formed on the film-formation target substrate. FIG. 2(a) shows an example in which two substances are used as deposition materials, and FIG. 2(b) shows an example in which three substances are used as deposition materials. Although examples in which two substances are used as deposition materials and examples in which three substances are used as deposition materials are shown here, the present invention is not limited to these examples.

[0021] When two substances are used as deposition materials, as shown in Figure 2(a), when the vapor of the deposition material ejected from each of the two vacuum deposition sources 21 and 22 reaches the surface of the substrate 30 to be deposited and solidifies, a multilayer film 310 of thin films 311 and 312 of the deposition material is formed on the surface of the substrate 30 to be deposited. For example, an NBP filter is fabricated by alternately stacking 66 layers of SiO2 / TiO2 on a film-forming substrate 30 made of an optical glass substrate. For example, the center wavelength of the transmission band is 827 nm, and the bandwidth is 12 nm or less.

[0022] When three substances are used as deposition materials, as shown in Figure 2(b), when the vapor of the deposition material ejected from each of the three vacuum deposition sources reaches the surface of the substrate 30 to be film-formed and solidifies, a multilayer film 320 of thin films 321, 322, and 323 of the deposition material is formed on the surface of the substrate 30 to be film-formed. For example, a BP filter is fabricated by alternately stacking 66 layers of SiO2 / Si3N4 / a-SiN:H on a film-forming target substrate 30 made of an optical glass substrate. For example, the center wavelength of the transmission band is 940 nm. Although examples of two and three layers have been described above, in an example of the method for controlling and optimizing the deposition of each layer in a multilayer optical thin film to be described later, 37 layers are laminated.

[0023] Furthermore, for example, an ion source 23 for irradiating ions such as oxygen ions onto a substrate on which a film is to be formed is provided in the vacuum chamber 10, and ion beam assisted vacuum deposition can be performed. By irradiating ions from the ion source 23 onto the film formation surface of the substrate 30 to be film-formed, a film can be formed while simultaneously carrying out two processes: a process in which a film is formed using the deposition material supplied from the film-forming material supply unit 20, thereby increasing the film thickness, and a process in which a portion of the surface of the already formed film is sputtered by ions irradiated from the ion source 23, thereby decreasing the film thickness. In this case, if a difference in film thickness occurs within the surface of the substrate 30 to be film-formed due to the density distribution of the film-forming substance supplied from the film-forming material supply unit 20, a multilayer film with a uniform in-plane film thickness distribution can be obtained by performing sputtering using ions irradiated from the ion source 23 under conditions that cancel out the difference in film thickness.

[0024] In this embodiment, a light projecting unit 40 that projects monitor light L onto a film-forming target substrate 30 held by a substrate holder 31 is provided. The light projecting unit 40 is installed outside the vacuum chamber 10 and includes a light source 41 as a light projecting head that projects monitor light L onto the film formation target substrate 30. As the light source 40, for example, a halogen lamp can be used.

[0025] A light receiving section 50 is provided which receives monitor light L transmitted through the film-forming target substrate 30 and the thin film and multilayer film being formed, and outputs a light receiving signal SR. The light receiving unit 50 is provided, for example, in the vacuum chamber 10, and is composed of a light receiving lens 51 as a light receiving head of the light receiving unit that receives monitor light L that has passed through the substrate to be film-formed and the thin film and multilayer film being formed, a spectroscopic unit 52 consisting of a spectrophotometer that disperses the monitor light received by the light receiving lens 51, a light detection unit 53 that detects the light dispersed by the spectroscopic unit 52, and a light receiving optical system 54 such as an optical fiber that transmits the monitor light L received by the light receiving lens 51 to the spectroscopic unit 52.

[0026] For example, the light detection unit 53 has a configuration in which light receiving pixels that convert received light into optical signals are arranged in a matrix, and a CCD sensor or the like can be used as the light detection unit 53. The monitor light L transmitted through the film formation target substrate 30 is received by the light receiving lens 51, transmitted to the spectroscopic section 52 by the light receiving optical system 54 and dispersed, and the dispersed monitor light is detected by the light detection section 53. The monitor light L transmitted through the film-forming target substrate 30 is dispersed by the spectroscopic section 52, and the dispersed light is detected by the photodetector section 53, which has light-receiving pixels arranged in a matrix, and outputs a photodetection signal SR. The photodetector section 53 can acquire a continuous spectrum of the monitor light, i.e., can detect the monitor light at multiple wavelengths.

[0027] The light receiving signal SR detected by the light detecting section 53 is supplied to a control section 60 configured by a personal computer (PC) or the like. In addition, a radiation temperature signal detected by a radiation thermometer 70 for measuring the substrate temperature during film formation is also supplied to the control unit 60. The control unit 60 processes the light reception signal SR to obtain the light transmittance of the film formation target substrate 30. Furthermore, by obtaining the continuous spectrum of the monitor light as described above, the control unit 60 obtains the light transmission spectrum of the film formation target substrate 30. The control unit 60 can provide feedback during film formation based on the obtained light transmittance or light transmission spectrum so as to change the film formation conditions so as to obtain desired optical characteristics. In this way, the control unit 60 acquires the light transmittance of the substrate 30 to be film-formed in accordance with the light receiving signal SR, and performs film formation control in which the thin film formation is controlled in an optimal control mode in association with the acquired light transmittance information, as described below.

[0028] FIG. 3 is a block diagram of the internal configuration of the control unit 60 shown in FIG. 3, the control unit 60 is a personal computer (PC) having a configuration in which a RAM 61, a ROM 62, a display monitor 64, a keyboard 65, and a mouse 66 are connected to a CPU 63, and the CPU 63 is configured to perform film formation control (described later) in accordance with a film formation control program stored in the ROM 62, based on instructions input by an operator via the keyboard 65 and the mouse 66. The film formation control by the CPU 63 is performed while the control contents are displayed on the display monitor 64. The film formation control program also includes a program for optimizing film formation control for each layer in a multilayer optical thin film, which will be described later.

[0029] Here, in this embodiment, before actually depositing each layer in the multilayer optical thin film, a simulation of the deposition of each layer in the multilayer optical thin film is performed using a plurality of control modes (in this embodiment, control mode TMA, control mode TMF, control mode TPC, control mode LR, control mode LV, and control mode NPV), and based on the results of the simulation, an optimal control mode is automatically selected for each layer from the plurality of control modes, and each layer is deposited using the selected optimal control mode.

[0030] The above-mentioned control mode TMA is time control using the average value of the deposition rate of each layer that has already been deposited, control mode TMF is time control using the measured deposition rate of the layer currently being deposited, control mode TPC is total phase compensation control, control mode LR is proportional control, control mode LV is light intensity control, and control mode NPV is control that compensates for the peak value predicted for the next layer. In this embodiment, six control modes, namely, control mode TMA, control mode TMF, control mode TPC, control mode LR, control mode LV, and control mode NPV, are used as the multiple control modes, but this is not limited to these, and any number and types of multiple control modes are possible.

[0031] Next, a method for controlling and optimizing the deposition of each layer in a multilayer optical thin film will be described. The method for optimizing control of film formation for each layer is executed by a CPU 63 in accordance with the program for optimizing control of the film formation control program stored in a ROM 62 in the control unit 60 constituted by the personal computer (PC). In this case, the program for the control optimization method is stored in advance in the ROM 62 of the control unit 60 as part of the film formation control program, and the CPU 63 of the control unit 60 reads out the program for the control optimization method and executes the control optimization method. However, this is not limited to this, and a film formation control program having the program for the control optimization method may be stored in a predetermined storage medium, and the CPU 63 of the control unit 60 may access the storage medium to read out the program for the control optimization method from the film formation control program and execute the control optimization method.

[0032] FIG. 4 is a flowchart of a method for optimizing deposition control of each layer in a multilayer optical thin film, and FIGS. 5, 6, and 8 to 14 are diagrams showing examples of control content screens displayed on the display monitor 64 in the method for optimizing deposition control of each layer shown in FIG. In this embodiment, a case where a 37-layer BPF is formed using the six control modes based on the film formation control program is shown.

[0033] First, in step 101 of FIG. 4, in accordance with instruction information input by the operator to the keyboard 65, a program for a control optimization method of the film formation control program stored in the ROM 62 is read out, and the program for the control optimization method is executed by the CPU 63, which then opens a setting display screen for the control optimization method on the display monitor 64. That is, when the control optimization method program is executed under the control of the CPU 63 in accordance with instruction information input by the operator using the keyboard 65 and mouse 66, a setting display screen 80 such as that shown in FIG. 5 is opened on the display monitor 64.

[0034] Next, in step 102, the CPU 63 opens a simulation setting display screen on the display monitor 64 in accordance with the instruction information input by the operator, and in step 103, the simulation setting is performed. In this embodiment, Monte-Carlo simulation is used as the simulation, in which noise in transmittance measurement, refractive index error, spectrometer resolution, deposition rate instability, and the like are set as error factors. That is, when the operator clicks the Optimization button 80a on the setting display screen 80 shown in FIG. 5 using the mouse 66, a multiple batch simulation setting display screen 82 as shown in FIG. 6 is opened.

[0035] 6, the simulation setting display screen 82 has an item 82a for specifying the number of batches of simulation for optimization in a multi-batch simulation, and the operator specifies the number of batches in the batch production method by clicking the item 82a with the mouse 66 and inputting from the keyboard 65. This number of batches is usually set to a value of about 10 to 100 batches, and in this case, 64 batches is set. Furthermore, as shown in Fig. 6, a selection of an evaluation function for optimization (Requirement Type) 82b is performed. Here, for example, one of two types of evaluation function is selected: a Merit Function as shown in Fig. 7(a) or a Shape Function as shown in Fig. 7(b). That is, in this embodiment, the user is allowed to select from the two evaluation functions, the Merit Function or the Shape Function. In the example shown in Fig. 6, the Merit Function is selected. In addition, in this embodiment, two evaluation functions (Merit Function shown in FIG. 7(a) and Shape Function shown in FIG. 7(b)) are selected and used as evaluation functions for simulating each layer of the multilayer optical thin film, but this is not limited to this, and other evaluation functions may be selectively used.

[0036] FIG. 7 is a diagram showing two evaluation function formulas that are selectively set in the simulation setting in step 103 of FIG. The physical parameters in the merit function shown in FIG. 7(a) and the shape function shown in FIG. 7(b) are as follows: The parameter N indicates the number of data points in the domain of the merit function. The parameter i indicates the index representing each data point. 6, a requirement value 82c for a non-defective product is set, where 2 is set as the requirement value for a non-defective product.

[0037] Next, in step 104 of FIG. 4, the various error factors described above are set. That is, when the operator uses the mouse 66 to click on the Set Errors in Simulation button 82d on the simulation setting display screen 82 shown in FIG. 6, simulation error setting display screens 83 and 84 as shown in FIGS. 8 and 9 are opened. 8, the simulation error setting display screen 83 has an item 83a for specifying the trigger rate calculated from the dome rotation speed, and the operator specifies the trigger rate by clicking the item 83a with the mouse 66. In this case, 1.5 seconds is set.

[0038] As shown in FIG. 8, the simulation error setting display screen 83 has a Source Error item 83b for inputting the error for each material, and the operator sets the error for each material by clicking on the item 83b with the mouse 66. As shown in FIG. 8, the simulation error setting display screen 83 has a Detector item 83c for setting the resolution and noise of the spectroscopic unit 52, and the operator can set the resolution and noise of the spectroscopic unit 52 by clicking on the item 83c using the mouse 66. The minimum wavelength, maximum wavelength, and wavelength step in item 83c of FIG. 8 define the wavelengths used to evaluate the characteristics of the final product. Also, do not select too wide a wavelength range, but only select the wavelength range that is of particular interest to the product. After changing the "Detector" settings, click "Update Virtual Detector" at the bottom with the mouse 66 to update the settings of the virtual spectroscopic unit 52.

[0039] Furthermore, as shown in FIG. 9, when the operator uses the mouse 66 to click on the Source Error item 84a on the simulation error setting display screen 84, the "Stop Delay" for each source is set to 0 when control optimization is performed. The "Stop Delay" of each source is set to 0, and the value is reset after control optimization and before actual film formation. When the settings for the various errors are completed, the Machine Form Window shown in FIGS. 8 and 9 is closed.

[0040] Next, in step S105 of Fig. 4, the simulation set as described above is executed from the nth layer. In this case, n = 1, and the simulation is executed from the first layer. In this embodiment, the simulation is executed from the first layer, but it may also be executed from the final layer and terminated at the first layer. That is, when the Machine Form Window as shown in Figures 8 and 9 is closed, a Simulation Execution window 85 as shown in Figure 10 is displayed, and when the operator clicks on the Start Batch item 85a in the Simulation Execution window 85 using the mouse 66, the simulation is executed from the nth layer (first layer). As described above, in the simulation of this embodiment, in the nth layer (first layer), simulation is performed in order in each of the control modes TMA, TMF, TPC, LR, LV, and NPV.

[0041] Next, in step S106 of FIG. 4, as described above, simulations are sequentially performed in the nth layer using each control mode: TMA, TMF, TPC, LR, LV, and NPV. Then, in step S107, the simulations performed in each control mode in the nth layer are evaluated. That is, the residuals at each wavelength point between the design spectrum and the predicted spectrum of the simulation for each control mode are calculated, and the sum of absolute values or sum of squares of the residuals are used for evaluation. Here, the evaluation uses the evaluation function set by the user in step 103 above.

[0042] Next, in step 108, the optimum control mode is selected based on the results of the simulation using each control mode evaluated by the evaluation function. That is, for the results of a large number of film formations performed in the simulation, the average value of the evaluation function selected as described above is calculated for each control mode of the nth layer, and the control mode with the smallest error is selected as the optimal control mode.

[0043] Next, in step 109, it is determined whether the nth layer of the simulated multilayer optical thin film is the final layer, and if the nth layer is the final layer, the process proceeds to the next step 110, and if the nth layer is not the final layer, in step 111, n+1 is set as a new n, and the process returns to step 105. In this display example, the final layer is the 37th layer. When a simulation is performed in each layer using multiple control modes, the progress can be displayed. For example, a simulation result display screen 86 as shown in FIG. 11 can be displayed as the progress. The display screen 86 of the simulation results shown in FIG. 11 shows a state in which the simulation has been completed for the first to tenth layers in the case of a film formation simulation for a 37-layer BPF.

[0044] In the simulation result display screen 86 shown in FIG. 11, the distribution of evaluation values of the expected film formation results (Expected Merit Func Distribution) for each of the plurality of control modes is displayed as a bar graph in a graph display section 86a. The bar graph in the graph display section 86a shown in FIG. 11 shows the distribution of the evaluation values of the predicted film formation results for each control mode for the 10th layer, with the horizontal axis representing the evaluation value and the vertical axis representing the frequency. In this case, the control mode TPC (thick line) 86b shows that it has the smallest average error evaluation value. On the right side of FIG. 11, there is provided a control optimization result display section 86c that displays the results of control optimization for each layer for which calculations have been completed, and the evaluation values of the predicted film formation results for each control mode for this 10th layer are displayed. That is, on the control optimization result display section 86c, for the 10th layer, it is displayed that Layer, L=10, BestCTRL=TPC, EvalMean=0.16990, EvalSTD=0.11821, Defects=0, indicating that the control mode TPC has the smallest average error evaluation value.

[0045] Next, when the simulation is completed up to the final layer, the optimization results are saved in step 110. That is, the optimal control mode for each layer, which is the result of evaluation of a simulation using multiple control modes in each layer (in this embodiment, control mode TMA, control mode TMF, control mode TPC, control mode LR, control mode LV, and control mode NPV), is saved. FIG. 12 is a diagram showing an example of a control content display screen displayed on the display monitor 64, showing the saved state of the optimal control mode for each layer as an evaluation result of a simulation using a plurality of control modes for each layer. For example, as shown in FIG. 12(a), when the Layer Number 87c on the simulation result display screen 87a is 37, indicating that the simulation has been completed up to the final layer, 37, if the operator clicks the Apply and Save the Results for the runsheet button 87d, the optimal control mode for each layer is displayed and saved in RAM 61, as shown on the display screen 87b in FIG. 12(b).

[0046] Next, in step 112, when the operator inputs an instruction to perform deposition of a multilayer optical thin film, the CPU 63 of the control unit 60 reads out a deposition control program from the ROM 62 of the control unit 60, and based on the deposition control program, the CPU 63 of the control unit 60 reads out the optimum control mode for each layer stored in the RAM 61, and performs the deposition process based on the optimum control mode for each layer. That is, the control unit 60 acquires the light transmittance of the film-forming target substrate 30 in response to the light-receiving signal SR, and controls the thin film formation in an optimum control mode in association with the acquired light transmittance information. An example of control in the film forming process based on each of the above control modes is shown in FIGS. Fig. 13 is a diagram showing an example of film formation control using a fitting function in the film formation process of step 112 in Fig. 4, and Fig. 14 is a diagram showing an example of film formation control using proportional control in the film formation process of step 112 in Fig. 4. In Fig. 13 and Fig. 14, the graphs show an example of the time change in transmittance during deposition for a certain layer and a certain monitoring wavelength, and by fitting the transmittance change with a predetermined function, physical variables such as the peak value excluding noise, the current transmittance value, the deposition rate, the reflection amplitude, and the phase are calculated, and from these, different variables are focused on for each control, and control is performed so that they match the design value.

[0047] As described above, according to this embodiment, before each layer of the multilayer optical thin film is actually deposited, a simulation of the deposition of each layer of the multilayer optical thin film is performed using a plurality of control modes consisting of control mode TMA, control mode TMF, control mode TPC, control mode LR, control mode LV, and control mode NPV. For each layer, an optimum control mode is automatically selected from the plurality of control modes, and each layer is deposited using the selected optimum control method. This reduces the burden on the operator while reducing the average and standard deviation of errors in each layer.

[0048] Although the present embodiment has been described above, the description and drawings that form part of this disclosure should not be understood as limiting, and various embodiments not described herein are also included. That is, the vacuum deposition apparatus of this embodiment is merely an example, and any configuration may be used as long as it is a thin film forming apparatus that executes a film formation control program including the film formation control optimization method program for each layer. Furthermore, in this embodiment, six control modes, namely, control mode TMA, control mode TMF, control mode TPC, control mode LR, control mode LV, and control mode NPV, are used as the multiple control modes in the simulation performed before depositing each layer of the multilayer optical thin film, but this is not limited to these, and any number and types of multiple control modes are possible. In addition, in this embodiment, two evaluation functions (Merit Function shown in FIG. 7(a) and Shape Function shown in FIG. 7(b)) are selected and used as evaluation functions for simulating each layer of the multilayer optical thin film, but this is not limited to this, and other evaluation functions may be selectively used. In this embodiment, a control optimization method program for simulating deposition of each layer in a multilayer optical thin film in a plurality of control modes and automatically selecting an optimal control mode from the plurality of control modes for each layer based on the results of the simulation is stored in advance in ROM 62 of control unit 60 as part of the deposition control program, and CPU 63 of control unit 60 reads out the control optimization method program and executes the control optimization method. However, without being limited to this, a deposition control program having the control optimization method program may be stored in a predetermined storage medium, and the storage medium may be accessed to read out the control optimization method program for the deposition control program and execute the control optimization method. [Explanation of symbols]

[0049] 10: Vacuum chamber; 20: Film forming material supply unit; 21: First vacuum evaporation source; 211: First evaporation material; 22: Second vacuum evaporation source; 221: Second evaporation material; 23... Ion source, 30, 310-320... Film formation target substrate, 31 substrate holder, 32 holder support portion, 40 light projecting portion, 41 light source, 50: Light receiving unit, 51: Light receiving lens, 52: Spectroscopic unit, 53: Light detection unit, 54....Light receiving optical system, 60....Control unit, 61....RAM, 62....ROM, 63···CPU, 64···Display monitor, 65···Keyboard, 66···Mouse, 70...Radiation thermometer, 80~87...Display screen, SR...Light reception signal, 101~112...each step

Claims

1. A thin film forming apparatus for forming a multilayer optical thin film on a film formation target substrate, a control unit that controls the deposition of a thin film on the film deposition target substrate in response to a light reception signal obtained by receiving monitor light that has passed through the film deposition target substrate; The control unit Before the deposition operation of the multilayer optical thin film, a simulation of deposition of each layer in the multilayer optical thin film is performed in a plurality of control modes; automatically selecting an optimal control mode from the plurality of control modes for each of the layers based on the results of the simulation; The thin film forming apparatus for a multilayer optical thin film controls the deposition of each layer of the multilayer optical thin film in accordance with the selected optimum control mode.

2. 2. The thin film forming apparatus according to claim 1, wherein the control unit evaluates the simulation performed for each layer, and selects an optimum control mode from among the plurality of control modes depending on the evaluation results.

3. 3. The thin film forming apparatus according to claim 2, wherein the evaluation of the simulation is performed in the control unit using a predetermined evaluation function.

4. 4. The thin film forming apparatus according to claim 3, wherein the evaluation of the simulation is performed using an evaluation function selected from a plurality of types of evaluation functions.

5. 5. The thin film forming apparatus according to claim 3, wherein the optimum control mode is selected by calculating an average value of the evaluation function for each control mode of a predetermined layer, and selecting the control mode with the smallest error.

6. The thin film forming apparatus according to claim 2, wherein the control unit stores the optimal control mode for each layer as a result of evaluation of the simulation when the simulation is completed for the first to final layers in the multilayer optical thin film.

7. The thin film forming apparatus according to claim 6, wherein the control unit executes deposition control of each layer of the multilayer optical thin film using the stored optimal control mode for each layer based on an instruction input for depositing the multilayer optical thin film.

8. A thin film forming apparatus for forming a multilayer optical thin film on a substrate to be formed, comprising: a light projection unit that projects monitor light onto a film formation target substrate on which a thin multilayer film is formed by depositing a film formation material supplied from a film formation material supply unit disposed in the film formation chamber; a light receiving section that receives the monitor light transmitted through the film formation target substrate and outputs a light receiving signal; a temperature measuring unit for measuring the substrate temperature during film formation; a control unit that acquires the light transmittance of the film formation target substrate in response to the light receiving signal and controls the formation of a thin film in association with the acquired light transmittance information, The control unit Before the deposition operation of the multilayer optical thin film, a simulation of deposition of each layer in the multilayer optical thin film is performed in a plurality of control modes; automatically selecting an optimal control mode from the plurality of control modes for each of the layers based on the results of the simulation; The thin film forming apparatus for a multilayer optical thin film controls the deposition of each layer of the multilayer optical thin film in accordance with the selected optimum control mode.

9. 9. The thin film forming apparatus according to claim 8, wherein the control unit evaluates the simulation performed for each layer and selects an optimal control mode from among the plurality of control modes based on the evaluation results.

10. A thin film formation method for forming a multilayer optical thin film on a film formation target substrate, in a thin film formation apparatus for forming a multilayer optical thin film on a film formation target substrate, the method comprising: performing, by the control unit, a simulation of film formation of each layer in the multilayer optical thin film in a plurality of control modes before a film formation operation of the multilayer optical thin film; automatically selecting an optimum control mode from the plurality of control modes for each layer based on a result of the simulation by the control unit; and controlling the control unit to control the deposition of each layer of the multilayer optical thin film in the selected optimum control mode.

11. The thin film forming method according to claim 10, wherein the selection step evaluates the simulation performed for each layer, and selects an optimum control mode from the plurality of control modes according to the evaluation results.

12. 12. The thin film forming method according to claim 11, wherein the evaluation of the simulation is performed in the control unit using a predetermined evaluation function.

13. 13. The thin film forming method according to claim 12, wherein the evaluation of the simulation is performed using an evaluation function selected from a plurality of types of evaluation functions.

14. The thin film formation method according to claim 12 or 13, wherein the control unit calculates the average value of the evaluation function for each control mode of a specified layer, and selects the control mode with the smallest error as the optimal control mode.

15. A thin film forming apparatus for forming a multilayer optical thin film on a film formation target substrate, the apparatus comprising: a control unit made of a computer that controls thin film formation on the film formation target substrate in response to a light reception signal obtained by receiving monitor light transmitted through the film formation target substrate, A program for causing the computer to execute the following steps: a step of performing a simulation of the deposition of each layer in the multilayer optical thin film in a plurality of control modes before the deposition operation of the multilayer optical thin film; a step of automatically selecting an optimum control mode from the plurality of control modes for each of the layers based on a result of the simulation; A procedure in which the control unit controls deposition of each layer of the multilayer optical thin film in the selected optimum control mode.

16. A storage medium storing the program according to claim 15.

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