WO2002061169A1 - Procede et dispositif pour former un film et procede de fabrication d'un element optique - Google Patents

Procede et dispositif pour former un film et procede de fabrication d'un element optique Download PDF

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Publication number
WO2002061169A1
WO2002061169A1 PCT/JP2002/000817 JP0200817W WO02061169A1 WO 2002061169 A1 WO2002061169 A1 WO 2002061169A1 JP 0200817 W JP0200817 W JP 0200817W WO 02061169 A1 WO02061169 A1 WO 02061169A1
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WO
WIPO (PCT)
Prior art keywords
film
thickness
monitor substrate
multilayer film
film forming
Prior art date
Application number
PCT/JP2002/000817
Other languages
English (en)
Japanese (ja)
Inventor
Takayuki Akiyama
Mayumi Hagiwara
Masayuki Ohtani
Original Assignee
Nikon Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nikon Corporation filed Critical Nikon Corporation
Publication of WO2002061169A1 publication Critical patent/WO2002061169A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/54—Controlling or regulating the coating process
    • C23C14/542—Controlling the film thickness or evaporation rate
    • C23C14/545—Controlling the film thickness or evaporation rate using measurement on deposited material

Definitions

  • the present invention relates to a film forming method, an optical element manufacturing method, and a film forming apparatus.
  • the present invention relates to a film forming method for forming a multilayer film such as an optical multilayer thin film filter for optical communication on the surface of an optical element, a method for manufacturing an optical element, and a film forming apparatus.
  • An optical element for optical communication has a multilayer film formed on its surface in order to make the transmittance and the reflectance for each wavelength have predetermined characteristics and to transmit only light of a specific wavelength.
  • the number of layers of this multilayer film may reach several tens to hundreds of tens of layers. By controlling the thickness of each film constituting the multilayer film, predetermined characteristics can be obtained.
  • FIG. 1 shows an example of a method for forming such a multilayer film.
  • (a) is a view of the substrate holder 1 described below from below, and (b) is an end view of the device at the position AA ′.
  • a substrate holder 2 is provided in the vacuum chamber 11 and rotates around a rotation axis 3.
  • An optical element 4 for forming a film on the surface is concentrically mounted on the lower surface of the substrate holder 12, and a monitor substrate 5 is mounted at one place where the optical element 4 is mounted.
  • a sputtering device 6 is provided below the vacuum chamber 11, from which particles of components constituting the film fly out, and hit the surfaces of the optical element 4 and the monitor substrate 5 to form a film.
  • windows 7 are provided on the upper and lower surfaces of a part of the vacuum chamber 11 so that light emitted from the light emitter 8 is transmitted through the optical element 4 or the monitor substrate 5 and received by the light receiver 9.
  • the spectral transmittance can be measured It has become so. The measurement of the spectral transmittance is performed for measuring the film thickness.
  • the monitor substrate 5 is made of a transparent flat plate, and is a dummy optical element used for measuring a film thickness. That is, by measuring the thickness of the film formed on the monitor substrate, the film thickness on the optical element 4 formed under the same conditions is indirectly measured.
  • the formation of a multilayer film using an apparatus as shown in FIG. 1 is performed as follows. First, the material of the film, the number of layers, and the thickness of each layer are determined by calculation so as to obtain predetermined optical characteristics (reflectance, transmittance, phase characteristics, and the like). When the design is completed in this way, first, the first layer is formed. If the film thickness can be measured without stopping the rotation of the substrate holder 2, the spectral transmittance is measured each time the monitor substrate 5 passes the positions of the projector 8 and the receiver 9, and a method described later is used. Use and measure the film thickness. Of course, since the approximate time required to form the predetermined film thickness is obtained by calculation, the measurement of the film thickness may be performed after a time close to this time has elapsed.
  • the film thickness is measured and film formation is continued, and the measured optical characteristics are the reference optical characteristics (optical characteristics that should be obtained when the target film thickness is obtained, and are often determined by theoretical calculations) )
  • the first layer deposition is completed, and the material used for sputtering is changed to perform the second layer deposition.
  • the final film U is measured and film formation is continued, and the measured optical characteristics are the reference optical characteristics (optical characteristics that should be obtained when the target film thickness is obtained, and are often determined by theoretical calculations)
  • a film forming apparatus having a function of measuring a spectral transmittance characteristic of a monitor substrate and calculating a film thickness by a fitting method from the moment is known, for example, “Vacuum Vol. 151 p.647-654 "and” Optical Design Research Group of the Optical Society of Japan N0.18 p.9-14 ".
  • FIG. 2A shows a state in which the multilayer thin film M is formed on the monitor substrate 5.
  • FIG. The multilayer thin film M has a state in which n layers M1 to Mn are formed, and in this state, the thickness dn of the nth layer thin film Mn is measured.
  • What is measured at this time is the spectral transmittance determined by the entire multilayer thin film M and the monitor substrate 5. That is, if the spectral transmittance at this time is T n, T n is
  • ⁇ ⁇ (E, dl'd2,, d (n.I), dn, al, a2,, a (n-l), an)-(l)
  • dl to d (n-1) and a1 to an in equation (1) are known.
  • dn is the target value of dn.
  • dn in equation (1) To calculate the spectral transmittance. Assume that the result is a curve indicated by A (solid line) in FIG. 2 (b), for example.
  • dn is dn . + ⁇ , dn. Assuming one ⁇ , these values are substituted into equation (1) to calculate the spectral transmittance.
  • ⁇ dashex-dot line
  • d n is the target value d n.
  • the spectral transmittance curve obtained when shifted from ⁇ ⁇ ⁇ (m is an appropriate integer) is calculated in advance, and the one closest to the actually measured spectral transmittance curve is selected and the corresponding curve is selected.
  • FIG. 5 shows the design value and the actual value of the spectral transmittance of an interference filter manufactured by forming a multilayer film having a thickness of 20 m while determining the film thickness using the above-described method.
  • FIGS. 5 and 6 show design values and actual values of the spectral transmittance of an edge filter manufactured by forming a multilayer film having a thickness of 26 m while determining the film thickness using the above-described method.
  • the design values are indicated by broken lines, and the actual values are indicated by solid lines.
  • the present invention has been made to solve such a problem, and a film forming method capable of forming an accurate film thickness even when the total film thickness of a multilayer film formed on an object is increased. It is an object of the present invention to provide a method for manufacturing an optical element and a film forming apparatus.
  • a film is formed on the surface of a monitor substrate under the same conditions as the surface of the object.
  • the thickness of the layer formed on the monitor substrate is measured, and from the thickness, the corresponding layer formed on the surface of the object is measured.
  • a method of estimating the thickness of the monitor substrate comprising a step of replacing the monitor substrate at least once during a series of film formation steps, and at least one of the monitor substrates, This is a film formation method characterized by being used for forming a layer thickness.
  • measuring the thickness of the layer on which the film formation is completed on the monitor substrate does not necessarily mean measuring the thickness every time the film formation of each layer is completed for all the layers. This includes the case where the thickness is measured only for some layers.
  • the total film thickness of a multilayer film that handles light with a long wavelength is large, so when such a multilayer film is formed, the total film thickness on the monitor substrate is also large, and the accuracy of film thickness measurement is significantly reduced. .
  • this means is particularly effective when forming a multilayer film on an optical element that handles light in the near infrared region (900 nm to 2500 nm).
  • the replacement of the monitor substrate which is a characteristic feature of the present invention, is performed by measuring the optical characteristics of the monitor substrate on which the multilayer film is formed and measuring the optical characteristics of the layer formed on the monitor substrate.
  • the method for measuring the thickness is to measure the optical characteristics of the monitor substrate on which the multilayer film is formed over at least three wavelengths, and to determine the relationship between the film thickness and the optical characteristics at the wavelengths obtained in advance by calculation, The effect is particularly remarkable when the thickness of the layer formed on the monitor substrate is measured by fitting calculation with the measured value of the optical property of the monitor substrate.
  • a target is set based on a deviation between a target value and an actual value of the thickness of a multilayer film whose thickness has been measured in a series of film forming steps in the past and whose thickness has been measured. If there is a process to correct the newly formed film thickness so that the optical characteristics of the multilayer film to be obtained can be obtained, the results measured using each monitor substrate can be used It is preferable to modify the film thickness to be formed. By doing so, the continuity of the measurement and the above-described “automatic error correction function” can be maintained even when the monitor board is replaced and used.
  • the total thickness of the monitor substrate is changed when the monitor substrate is replaced depends on the required accuracy of the film thickness measurement and the accuracy of the measuring device. Those skilled in the art can appropriately determine them according to the film conditions.
  • the monitor substrate it is particularly preferable to replace the monitor substrate when the total thickness of the multilayer film formed on the monitor substrate reaches a predetermined thickness between 1 and 10 ⁇ m.
  • the inventors have found that, in the above-described method for measuring the thickness of a multilayer film, when the film thickness to be formed exceeds about lOAm, the accuracy of the film thickness measurement is particularly deteriorated. This is because, as the total film thickness increases, the optical properties used to measure the film thickness, especially the spectral transmittance, change significantly with wavelength, and change significantly even with a very small change in wavelength. It is thought that it is to become.
  • the wavelength resolution of a generally used spectrometer is about 0.5 nm, and if the film thickness is to be measured with an accuracy of about ⁇ 0.1 nm in a region where the film thickness exceeds about 10 m, a wavelength of about 0.5 nm is required. With a spectrometer with a high resolution, the measurement accuracy becomes insufficient.
  • the difference between the design value and the actual value often needs to be about ⁇ 0.02%, and the wavelength resolution of the spectral transmittance meter normally obtained is about 0.5 nm. It is. Considering this, in order to secure the thickness measurement accuracy ⁇ 0.1 ⁇ actually required, According to the experiments by the inventors, it is necessary to reduce the total film thickness formed on the monitor substrate to at least 10 / m or less.
  • the total film thickness for determining the timing of replacing the monitor substrate is l to 10 zm.
  • the total film thickness for determining the timing of replacing the monitor substrate is l to 10 zm.
  • a method for manufacturing an optical element comprising a step of forming a multilayer film on a surface using the film forming method according to the first aspect. It is.
  • the film is formed on the surface of the optical element by the film forming method according to the first aspect of the invention, the film thickness of each layer is accurate, and therefore, an optical element having desired performance is manufactured. can do.
  • the optical element manufactured according to the present invention is particularly suitable for use as an optical multilayer film for optical communication.
  • a film is formed on the surface of a monitor substrate under the same conditions as the surface of the object.
  • the thickness of the layer formed on the monitor substrate is measured, and from the thickness, the thickness of the corresponding layer formed on the surface of the object is measured.
  • a film forming apparatus having a function of estimating a thickness of a layer, the function of exchanging the module substrate during a series of film forming steps. Since this means has a function of replacing the monitor substrate during a series of film forming steps, the first invention can be implemented, and the film thickness can be measured accurately.
  • measuring the thickness of the layer on which the film has been formed on the monitor substrate does not necessarily mean measuring the thickness every time the formation of each layer is completed for all the layers. This also includes the case where the thickness is measured only for some layers.
  • the replacement of the monitor substrate which is a characteristic feature of the present invention, is performed by measuring the optical characteristics of the monitor substrate on which the multilayer film is formed and measuring the optical characteristics of the layer formed on the monitor substrate.
  • the method for measuring the thickness is to measure the optical characteristics of the monitor substrate on which the multilayer film is formed over at least three wavelengths, and to determine the relationship between the film thickness and the optical characteristics at the wavelengths obtained in advance by calculation, The effect is particularly remarkable when the thickness of the layer formed on the monitor substrate is measured by fitting calculation with the measured value of the optical property of the monitor substrate.
  • the optical property of the target multilayer film is determined. If it has a function to correct the newly formed film thickness so that the characteristics can be obtained, the results measured using each monitor substrate can be used as it is to calculate the newly formed film thickness. It is preferable to have a function of correcting. By doing so, it is possible to maintain the continuity of the measurement and the above-described “automatic error correction function” even when the monitor board is replaced and used.
  • FIG. 1 is a diagram showing an example of a method for forming a multilayer film.
  • FIG. 2 is a diagram illustrating the principle of a method for measuring the film thickness based on the spectral transmittance.
  • FIG. 3 is a diagram showing the spectral transmittance of the interference filter manufactured by the method of the present invention.
  • FIG. 4 is a diagram showing the spectral transmittance of edge filters manufactured by the method of the present invention.
  • FIG. 5 is a diagram showing a spectral transmittance of an interference filter manufactured by a conventional method.
  • FIG. 6 is a diagram showing the spectral transmittance of an edge filter manufactured by a conventional method.
  • an interference filter having the same target characteristics as those shown in FIG. 5 was manufactured.
  • the total thickness of the multilayer film formed in the film was set to 20 zm.
  • the monitor board was replaced every time the measured total film thickness on the monitor board exceeded. That is, the film thickness was measured by replacing the monitor substrate four times.
  • the method of measuring the film thickness is the fitting method as described in the method of the prior art.
  • Figure 3 shows the design values (dashed lines) and the actual values (solid lines) of the spectral transmittance characteristics of the manufactured interference filter. As you can see from the results, the two agree very well. This means that at each stage of film formation, This indicates that the target thickness is controlled.
  • an edge filter having the same target characteristics as those shown in FIG. 6 was manufactured.
  • the total film thickness formed in the film was 26 m.
  • the monitor substrate was replaced every time the measured total film thickness on the monitor substrate exceeded 5 zm. That is, the film thickness was measured by changing the monitor substrate five times.
  • the method of measuring the film thickness is a fitting method as described in the method of the prior art.
  • Fig. 4 shows the design values (broken line) and the actual values (solid line) of the spectral transmittance characteristics of the manufactured edge fill. As you can see from the results, they match very well (because they almost completely match, the broken line and the solid line overlap and the broken line is not visible). This indicates that the film thickness is controlled to the target thickness at each stage of the film formation.
  • the film forming method, the optical element manufacturing method, and the film forming apparatus of the present invention can be used for forming a multilayer film on the surface of an optical element or the like.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Physical Vapour Deposition (AREA)

Abstract

Procédé et dispositif pour former un film et procédés de fabrication d'un élément optique. Ce dispositif comprend un support de substrat (2) monté dans une chambre à vide (1) et pivotant autour d'un arbre rotatif (3). Des éléments optiques (4), formés sur ce dernier sous forme de film, sont montés à la surface inférieure du support de substrat (2) en cercles concentriques par rapport à l'arbre rotatif. Un substrat de moniteur (5) est installé dans l'une des positions pour monter les éléments optiques (4). Le procédé consiste à mesurer l'épaisseur du film du substrat (5) pour estimer l'épaisseur du film formé sur les éléments optiques (4). Comme l'épaisseur du film sur le substrat de moniteur (5) augmente et que l'exactitude des mesures baisse à mesure que la formation d'un film avance et que l'épaisseur du film formé sur les éléments optiques (4) augmente, la formation du film est effectuée pendant le remplacement du substrat de moniteur (5) par un nouveau substrat, provenant de l'un des stades de formation de film. On peut empêcher ainsi la détérioration de l'exactitude de mesure du film et fabriquer un élément optique ayant les performances indiquées.
PCT/JP2002/000817 2001-02-01 2002-02-01 Procede et dispositif pour former un film et procede de fabrication d'un element optique WO2002061169A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2001-025052 2001-02-01
JP2001025052 2001-02-01

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103726019A (zh) * 2013-12-13 2014-04-16 中国科学院上海光学精密机械研究所 改善球面光学元件镀膜均匀性的挡板的设计方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS495834B1 (fr) * 1969-03-11 1974-02-09
JPS5521106B2 (fr) * 1975-10-17 1980-06-07
EP0634626A2 (fr) * 1993-07-15 1995-01-18 Matsushita Electric Industrial Co., Ltd. Appareil et méthode pour former des couches multiples
US5425964A (en) * 1994-07-22 1995-06-20 Rockwell International Corporation Deposition of multiple layer thin films using a broadband spectral monitor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS495834B1 (fr) * 1969-03-11 1974-02-09
JPS5521106B2 (fr) * 1975-10-17 1980-06-07
EP0634626A2 (fr) * 1993-07-15 1995-01-18 Matsushita Electric Industrial Co., Ltd. Appareil et méthode pour former des couches multiples
US5425964A (en) * 1994-07-22 1995-06-20 Rockwell International Corporation Deposition of multiple layer thin films using a broadband spectral monitor

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
B.T. SULLIVAN ET AL.: "Manufacture of complex optical multilayer filters using an automated deposition system", VACCUM, vol. 51, no. 4, 1998, pages 647 - 654, XP002951089 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103726019A (zh) * 2013-12-13 2014-04-16 中国科学院上海光学精密机械研究所 改善球面光学元件镀膜均匀性的挡板的设计方法
CN103726019B (zh) * 2013-12-13 2015-10-28 中国科学院上海光学精密机械研究所 改善球面光学元件镀膜均匀性的挡板的设计方法

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