Dielectric multilayer film substrate and method for manufacturing the same, optical multilayer film substrate and method for manufacturing the same

Abstract

This invention provides a dielectric multilayer film substrate that enables the design of films with desired optical properties, even when subjected to alkaline cleaning. [Solution] A dielectric multilayer film substrate 1 comprising a substrate 2, a multilayer film 3 provided on the substrate 2 having a portion in which a high refractive index film 6 with a relatively high refractive index and a low refractive index film 7 with a relatively low refractive index are alternately stacked, a mixed film 4 provided on the multilayer film 3 and containing a high refractive index component with a relatively high refractive index and a low refractive index component with a relatively low refractive index, and a sacrificial film 5 provided on the mixed film 4.

Description

Technical Field

[0001] The present invention relates to a substrate with a dielectric multilayer film, a method for manufacturing the substrate with a dielectric multilayer film, an optical multilayer film substrate using the substrate with a dielectric multilayer film, and a method for manufacturing the optical multilayer film substrate.

Background Art

[0002] Conventionally, a substrate with a dielectric multilayer film, in which a dielectric multilayer film is provided on a glass substrate, has been used. The dielectric multilayer film is used as an optical functional film such as an antireflection film, an infrared reflection film, a bandpass filter, and a mirror. For example, the dielectric multilayer film is used as an antireflection film for a cover glass used in an image sensor.

[0003] Patent Document 1 below discloses an optical multilayer film filter used as a bandpass filter or a mirror. As the optical multilayer film filter, a substrate with a dielectric multilayer film is used, which includes a glass substrate and a dielectric multilayer film formed by alternately laminating a high refractive index material layer and a low refractive index material layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the film formation surface of the substrate with a dielectric multilayer film may be subjected to alkali cleaning for the purpose of removing dirt or the like. In this case, a silicon oxide layer may be formed on the outermost layer of the dielectric multilayer film, which also serves as a protective layer during alkali cleaning. Thus, when a protective layer (sacrificial film) during alkali cleaning is formed on the outermost layer of the dielectric multilayer film, only the sacrificial film is dissolved during alkali cleaning, and the remaining multilayer film can be protected from the alkaline aqueous solution.

[0006] However, there is a problem in that it is difficult to selectively dissolve only the sacrificial film by alkaline cleaning. In particular, when the outermost layer of the multilayer film beneath the sacrificial film is a silicon oxide film, both the sacrificial film and the silicon oxide film beneath it are dissolved, reducing the thickness of the outermost silicon oxide film, which can result in a deterioration of the optical properties of the resulting dielectric multilayer film substrate. On the other hand, if a film resistant to alkaline cleaning is used for the outermost layer of the multilayer film beneath the sacrificial film, it may be difficult to design a film with the desired optical properties.

[0007] The object of the present invention is to provide a dielectric multilayer film substrate, a method for manufacturing the dielectric multilayer film substrate, and an optical multilayer film substrate using the dielectric multilayer film substrate, and a method for manufacturing the optical multilayer film substrate, which enable the design of films having desired optical properties even when subjected to alkaline cleaning. [Means for solving the problem]

[0008] The following describes a dielectric multilayer film substrate that solves the above problems, a method for manufacturing the dielectric multilayer film substrate, and various embodiments of an optical multilayer film substrate using the dielectric multilayer film substrate and a method for manufacturing the optical multilayer film substrate.

[0009] A dielectric multilayer film substrate according to Embodiment 1 of the present invention is characterized by comprising: a substrate; a multilayer film provided on the substrate, having a portion in which a high refractive index film having a relatively high refractive index and a low refractive index film having a relatively low refractive index are alternately stacked; a mixed film provided on the multilayer film, containing a high refractive index component having a relatively high refractive index and a low refractive index component having a relatively low refractive index; and a sacrificial film provided on the mixed film.

[0010] In the dielectric multilayer film substrate according to Embodiment 2, it is preferable that the mixed film of Embodiment 1 contains at least one high refractive index component selected from the group consisting of tantalum oxide, hafnium oxide, titanium oxide, and zirconium oxide.

[0011] In the dielectric multilayer film substrate according to Embodiment 3, it is preferable that the high refractive index component in the mixed film of Embodiment 1 or Embodiment 2 is tantalum oxide.

[0012] In the dielectric multilayer film substrate according to Embodiment 4, it is preferable that the low refractive index component in the mixed film of any one of Embodiments 1 to 3 is silicon oxide.

[0013] In the dielectric multilayer film substrate according to Embodiment 5, it is preferable that in the mixed film of any one Embodiment from Embodiment 1 to Embodiment 4, the ratio of the content of the high refractive index component to the low refractive index component (high refractive index component / low refractive index component) is 0.03 or more and 9.0 or less by mass ratio.

[0014] In the dielectric multilayer film substrate according to Embodiment 6, in any one embodiment from Embodiments 1 to 5, it is preferable that the refractive index of the mixed film at a wavelength of 550 nm is 1.3 or more and 2.1 or less.

[0015] In the dielectric multilayer film substrate according to Embodiment 7, it is preferable that the sacrificial film contains silicon oxide in any one embodiment from Embodiments 1 to 6.

[0016] In the dielectric multilayer film substrate according to embodiment 8, it is preferable that the low refractive index film in the multilayer film of any one embodiment from embodiment 1 to embodiment 7 contains silicon dioxide.

[0017] In the dielectric multilayer film substrate according to Embodiment 9, it is preferable that in the multilayer film of any one Embodiment from Embodiment 1 to Embodiment 8, the high refractive index film includes at least one selected from the group consisting of niobium oxide, titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silicon nitride, aluminum oxide, and aluminum nitride.

[0018] The method for manufacturing a substrate with a dielectric multilayer film according to Aspect 10 of the present invention includes a step of forming a multilayer film having a portion on a substrate where a high refractive index film having a relatively high refractive index and a low refractive index film having a relatively low refractive index are alternately laminated, a step of forming a mixed film including a high refractive index component having a relatively high refractive index and a low refractive index component having a relatively low refractive index on the multilayer film, and a step of forming a sacrificial film on the mixed film.

[0019] The method for manufacturing a substrate with an optical multilayer film according to Aspect 11 of the present invention includes a step of preparing a substrate with a dielectric multilayer film according to any one of Aspects 1 to 9, and a step of subjecting the substrate with the dielectric multilayer film to alkaline cleaning to remove the sacrificial film.

[0020] The substrate with an optical multilayer film according to Aspect 12 of the present invention includes a substrate, a multilayer film provided on the substrate and having a portion where a high refractive index film having a relatively high refractive index and a low refractive index film having a relatively low refractive index are alternately laminated, and a mixed film provided on the multilayer film and including a high refractive index component having a relatively high refractive index and a low refractive index component having a relatively low refractive index.

Effects of the Invention

[0021] According to the present invention, it is possible to provide a substrate with a dielectric multilayer film, a method for manufacturing the substrate with a dielectric multilayer film, a substrate with an optical multilayer film using the substrate with a dielectric multilayer film, and a method for manufacturing the substrate with an optical multilayer film, which enable a film design having desired optical characteristics even when alkaline cleaning is performed.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a substrate with a dielectric multilayer film according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a substrate with an optical multilayer film according to an embodiment of the present invention. [Figure 3]FIG. 3 is a diagram showing the light transmission spectra of the film-coated substrates obtained in each of the examples and comparative examples. [Figure 4] FIG. 4 is a diagram showing the results of the alkali immersion test of the film-coated substrates obtained in each of the reference examples.

Embodiments for Carrying Out the Invention

[0023] Hereinafter, preferred embodiments of the present invention will be described. However, the following embodiments are merely illustrative, and the present invention is not limited to the following embodiments. Also, in each drawing, members having substantially the same function may be referred to by the same reference numerals.

[0024] [Substrate with a dielectric multilayer film] FIG. 1 is a schematic cross-sectional view showing a substrate with a dielectric multilayer film according to an embodiment of the present invention.

[0025] As shown in FIG. 1, the substrate 1 with a dielectric multilayer film includes a substrate 2, a multilayer film 3, a mixed film 4, and a sacrificial film 5.

[0026] In the present embodiment, the substrate 2 has a substantially rectangular plate shape. However, the substrate 2 may have a substantially disc shape, and the shape is not particularly limited.

[0027] In the present embodiment, the substrate 2 is preferably a substrate that is transparent in the wavelength range of use of the substrate 1 with a dielectric multilayer film. For example, when the substrate 1 with a dielectric multilayer film is used as a cover glass for a display, the substrate 2 can have a light transmittance of 80% or more and 92% or less at a thickness of 0.4 mm and a wavelength of 350 nm to 800 nm.

[0028] The substrate 2 has a first main surface 2a and a second main surface 2b facing each other. The multilayer film 3 is provided on the first main surface 2a of the substrate 2.

[0029] In this embodiment, the multilayer film 3 is constructed by alternately stacking a high refractive index film 6, which has a relatively high refractive index, and a low refractive index film 7, which has a relatively low refractive index, in that order. However, the multilayer film 3 only needs to have a portion in which the high refractive index film 6, which has a relatively high refractive index, and the low refractive index film 7, which has a relatively low refractive index, are alternately stacked in that order, and may include other layers. Furthermore, the stacking order of the high refractive index film 6 and the low refractive index film 7 in the multilayer film 3 is not particularly limited. The material of the high refractive index film 6 is not particularly limited as long as it is a material with a relatively high refractive index, but in this embodiment it is niobium oxide. Similarly, the material of the low refractive index film 7 is not particularly limited as long as it is a material with a relatively low refractive index, but in this embodiment it is silicon oxide.

[0030] A mixed film 4 is provided on the multilayer film 3. The mixed film 4 is provided on the main surface 3a of the multilayer film 3 that is opposite to the substrate 2.

[0031] The mixed film 4 contains a high refractive index component with a relatively high refractive index and a low refractive index component with a relatively low refractive index. The material of the high refractive index component is not particularly limited as long as it is a material with a relatively high refractive index, but in this embodiment it is tantalum oxide. The material of the low refractive index component is not particularly limited as long as it is a material with a relatively low refractive index, but in this embodiment it is silicon oxide.

[0032] A sacrificial film 5 is provided on the mixed film 4. The sacrificial film 5 is provided on the main surface 4a of the mixed film 4 that is opposite to the substrate 2.

[0033] The sacrificial film 5 is a film that protects the surfaces of the multilayer film 3 and the mixed film 4 from dirt and other contaminants, and is a film that can be removed by alkaline cleaning or the like. For example, the sacrificial film 5 can be a film that dissolves about 10 nm in 10 minutes when immersed in a 3.0% by mass aqueous sodium hydroxide solution. However, the sacrificial film 5 can be any film that can be removed by alkaline cleaning or the like, and the amount of dissolution can be determined as appropriate and is not particularly limited.

[0034] When using the dielectric multilayer film-coated substrate 1, the sacrificial film 5 is removed, for example, by alkaline cleaning. While complete removal of the sacrificial film 5 is desirable, some of the sacrificial film 5 may remain on the dielectric multilayer film-coated substrate 1. Furthermore, the dielectric multilayer film-coated substrate 1 may be used with the sacrificial film 5 completely intact, and is not particularly limited to this method.

[0035] Since the dielectric multilayer film substrate 1 of this embodiment has the above configuration, it is possible to design a film with desired optical properties even when alkaline cleaning is performed.

[0036] Conventionally, when a sacrificial film is formed on the outermost layer of a dielectric multilayer film during alkaline cleaning, the design was such that only the sacrificial film would dissolve during alkaline cleaning. However, there was a problem in that it was difficult to selectively dissolve only the sacrificial film by alkaline cleaning. In particular, when the outermost layer of the multilayer film beneath the sacrificial film was a silicon oxide film, both the sacrificial film and the silicon oxide film beneath it would dissolve, reducing the thickness of the outermost silicon oxide film, and as a result, the optical properties of the resulting dielectric multilayer film-attached substrate could deteriorate. On the other hand, when a film resistant to alkaline cleaning was used for the outermost layer of the multilayer film beneath the sacrificial film, it was sometimes difficult to design a film with the desired optical properties.

[0037] In response to this, the inventors focused on the outermost layer beneath the sacrificial film 5 and found that by using a mixed film 4 containing a high refractive index component with a relatively high refractive index and a low refractive index component with a relatively low refractive index as the outermost layer beneath the sacrificial film 5, it becomes possible to design a film with desired optical properties while increasing the resistance of the outermost layer beneath the sacrificial film 5 to alkaline cleaning in the dielectric multilayer film substrate 1.

[0038] The following describes in more detail each layer that makes up the dielectric multilayer substrate 1.

[0039] (substrate) Examples of materials for substrate 2 include glass and resin. Alternatively, if the wavelength range used is in the infrared region, the substrate 2 material may also be Si or Ge. Examples of glass include soda-lime glass, borosilicate glass, alkali-free glass, crystallized glass, quartz glass, and fluoride glass. Aluminosilicate glass, used as tempered glass, may also be used.

[0040] The thickness of substrate 2 is not particularly limited. The thickness of substrate 2 can be set appropriately according to the light transmittance, etc. For example, the thickness of substrate 2 can be about 0.05 mm to 1.2 mm.

[0041] (Multilayer film) The multilayer film 3 is a dielectric multilayer film having a high refractive index film 6 and a low refractive index film 7.

[0042] The material of the high refractive index film 6 is not particularly limited as long as it is a material with a relatively high refractive index. Examples of materials for the high refractive index film 6 include niobium oxide, titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silicon nitride, aluminum oxide, or aluminum nitride. The high refractive index film 6 is preferably a film mainly composed of at least one selected from the group consisting of niobium oxide, titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silicon nitride, aluminum oxide, and aluminum nitride, and is more preferably a film mainly composed of niobium oxide, as in this embodiment.

[0043] The material of the low refractive index film 7 is not particularly limited as long as it is a material with a relatively low refractive index. Examples of materials for the low refractive index film 7 include silicon oxide and aluminum oxide. These materials for the low refractive index film 7 may be used individually or in combination of multiple types. The low refractive index film 7 is preferably a film mainly composed of at least one of silicon oxide and aluminum oxide, and more preferably a film mainly composed of silicon oxide.

[0044] In this specification, the term "main component membrane" refers to a membrane containing 50% or more of that component by mass, preferably 80% or more by mass, and more preferably 90% or more by mass. Naturally, it is preferable that the membrane is composed solely of that component, with impurities removed.

[0045] The number of layers of the high refractive index film 6 is not particularly limited, but is preferably 2 or more layers, more preferably 5 or more layers, even more preferably 7 or more layers, preferably 26 or fewer layers, more preferably 23 or fewer layers, and even more preferably 20 or fewer layers.

[0046] The number of layers of the low refractive index film 7 is not particularly limited, but is preferably 2 or more layers, more preferably 5 or more layers, even more preferably 7 or more layers, preferably 26 or fewer layers, more preferably 23 or fewer layers, and even more preferably 20 or fewer layers.

[0047] The total number of layers in the multilayer film 3 is not particularly limited, but is preferably 4 or more layers, more preferably 10 or more layers, even more preferably 20 or more layers, preferably 50 or fewer layers, more preferably 35 or fewer layers, and even more preferably 25 or fewer layers.

[0048] The thickness of each layer of the high refractive index film 6 is not particularly limited, but is preferably 1 nm or more, more preferably 2 nm or more, preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less.

[0049] The thickness of each layer of the low refractive index film 7 is not particularly limited, but is preferably 1 nm or more, more preferably 2 nm or more, preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less.

[0050] The overall thickness of the multilayer film 3 is not particularly limited, but is preferably 100 nm or more, more preferably 300 nm or more, even more preferably 500 nm or more, preferably 2000 nm or less, more preferably 1500 nm or less, and even more preferably 1000 nm or less.

[0051] (mixed membrane) The mixed film 4 contains a high refractive index component with a relatively high refractive index and a low refractive index component with a relatively low refractive index. As the high refractive index component, tantalum oxide, hafnium oxide, titanium oxide, or zirconium oxide can be used. These materials may be used individually or in combination. Among these, tantalum oxide is preferred as the high refractive index component.

[0052] Furthermore, the low refractive index component can be the material described for the low refractive index film 7, and silicon dioxide is preferred. While it is preferable to use the same material for the low refractive index component as for the low refractive index film 7, a different material may also be used.

[0053] The content of the high refractive index component in the mixed film 4 is preferably 3.0% by mass or more, more preferably 6.0% by mass or more, even more preferably 9.0% by mass or more, preferably 90% by mass or less, more preferably 75% by mass or less, even more preferably 50% by mass or less, and most preferably 25% by mass or less. When the content of the high refractive index component is above the lower limit, the resistance of the outermost layer under the sacrificial film 5 to alkaline cleaning can be further improved in the dielectric multilayer film substrate 1. Also, when the content of the high refractive index component is below the upper limit, the optical properties of the dielectric multilayer film substrate 1 can be further improved.

[0054] The content of the low refractive index component in the mixed film 4 is preferably 10% by mass or more, more preferably 25% by mass or more, even more preferably 50% by mass or more, most preferably 75% by mass or more, preferably 97% by mass or less, more preferably 94% by mass or less, and even more preferably 91% by mass or less. When the content of the low refractive index component is above the lower limit, the optical properties of the dielectric multilayer film-coated substrate 1 can be further improved. Also, when the content of the low refractive index component is below the upper limit, the resistance of the outermost layer under the sacrificial film 5 to alkaline cleaning in the dielectric multilayer film-coated substrate 1 can be further improved.

[0055] In the mixed film 4, the ratio of the content of the high refractive index component to the low refractive index component (high refractive index component / low refractive index component) is preferably 0.03 or more, more preferably 0.07 or more, even more preferably 0.11 or more, preferably 9.0 or less, more preferably 3.0 or less, even more preferably 1.0 or less, and most preferably 0.35 or less, in terms of mass ratio. Furthermore, when the mixed film 4 contains silicon oxide and tantalum oxide as in this embodiment, the ratio of the content of tantalum oxide to silicon oxide in the mixed film 4 (tantalum oxide / silicon oxide) is preferably 0.03 or more, more preferably 0.07 or more, even more preferably 0.11 or more, preferably 9.0 or less, more preferably 3.0 or less, even more preferably 1.0 or less, and most preferably 0.35 or less. When the above content ratio (high refractive index component / low refractive index component) is equal to or greater than the above lower limit, the resistance of the outermost layer under the sacrificial film 5 to alkaline cleaning can be further improved in the dielectric multilayer film-attached substrate 1. On the other hand, if the ratio of the above-mentioned content (high refractive index component / low refractive index component) is less than or equal to the above-mentioned upper limit, the optical properties of the dielectric multilayer film-coated substrate 1 can be further improved.

[0056] The proportion of each component in the film can be measured using a scanning transmission electron microscope (STEM-EDX, manufactured by Hitachi High-Tech Corporation, model number "HD-2700").

[0057] The refractive index of the mixed film 4 at a wavelength of 550 nm is preferably 1.3 or higher, more preferably 1.5 or higher, even more preferably 1.7 or higher, preferably 2.1 or lower, more preferably 2.0 or lower, and even more preferably 1.9 or lower. When the refractive index of the mixed film 4 at a wavelength of 550 nm is within the above range, it becomes easier to design the optical properties, such as the light transmittance, of the dielectric multilayer film-coated substrate 1 to the desired optical properties.

[0058] The refractive index can be measured using molecular ellipsometry (for example, the M-2000 from JA Woollam Japan).

[0059] The thickness of the mixed film 4 is not particularly limited, but is preferably 1.0 nm or more, more preferably 3.0 nm or more, even more preferably 5.0 nm or more, preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 15 nm or less. When the thickness of the mixed film 4 is within the above range, the resistance of the outermost layer under the sacrificial film 5 to alkaline cleaning can be further improved in the dielectric multilayer film substrate 1.

[0060] In this embodiment, the concentration of the high refractive index component in the thickness direction of the mixed film 4 is substantially constant, and the concentration of the low refractive index component in the thickness direction of the mixed film 4 is substantially constant. However, the mixed film 4 may contain a relatively large amount of the high refractive index component on the sacrificial film 5 side in the thickness direction, and a relatively large amount of the low refractive index component on the multilayer film 3 side in the thickness direction. Alternatively, the mixed film 4 may contain a relatively large amount of the low refractive index component on the sacrificial film 5 side in the thickness direction, and a relatively large amount of the high refractive index component on the multilayer film 3 side in the thickness direction. In either case, the dielectric multilayer film-attached substrate 1 can be made to further improve the resistance of the outermost layer under the sacrificial film 5 to alkaline cleaning, while further improving the optical properties of the dielectric multilayer film-attached substrate 1.

[0061] Furthermore, in the mixed film 4, the content of high refractive index components may increase from the multilayer film 3 side towards the sacrificial film 5 side in the thickness direction, or the content of low refractive index components may increase from the sacrificial film 5 side towards the multilayer film 3 side in the thickness direction. Alternatively, the content of low refractive index components may increase from the multilayer film 3 side towards the sacrificial film 5 side in the thickness direction, or the content of high refractive index components may increase from the sacrificial film 5 side towards the multilayer film 3 side in the thickness direction. In any case, the dielectric multilayer film-attached substrate 1 can be made to further improve the resistance of the outermost layer under the sacrificial film 5 to alkaline cleaning, while further improving the optical properties of the dielectric multilayer film-attached substrate 1.

[0062] (Sacrificial membrane) The sacrificial film 5 is preferably a film mainly composed of silicon dioxide. The thickness of the sacrificial film 5 can be appropriately set according to the planned degree of alkaline cleaning, and is preferably 1 nm or more, more preferably 3 nm or more, even more preferably 5 nm or more, preferably 19 nm or less, more preferably 17 nm or less, and even more preferably 15 nm or less.

[0063] (Substrate with dielectric multilayer film) The dielectric multilayer film-coated substrate 1 has a thickness of 0.4 mm and a light transmittance at wavelengths of 450 nm to 700 nm is preferably 95% or higher, more preferably 97% or higher, even more preferably 99% or higher, and particularly preferably 99.5% or higher.

[0064] In the dielectric multilayer substrate 1, the multilayer film 3, mixed film 4, and sacrificial film 5 are provided on the entire surface of the first main surface 2a of the substrate 2. However, in the present invention, the multilayer film 3, mixed film 4, and sacrificial film 5 may be partially provided on the first main surface 2a of the substrate 2. In addition, other films may be provided between the first main surface 2a of the substrate 2 and the multilayer film 3, or between the multilayer film 3 and the mixed film 4, etc.

[0065] Furthermore, in the dielectric multilayer substrate 1, the multilayer film 3, mixed film 4, and sacrificial film 5 are provided only on the first main surface 2a of the substrate 2. However, in the present invention, the multilayer film 3, mixed film 4, and sacrificial film 5 may also be provided on the second main surface 2b of the substrate 2.

[0066] The following describes a manufacturing method for a dielectric multilayer film substrate 1 as an example.

[0067] (Manufacturing method for substrates with dielectric multilayer films) First, prepare substrate 2. Next, deposit the multilayer film 3, mixed film 4, and sacrificial film 5 onto substrate 2 in this order. The deposit of the multilayer film 3, mixed film 4, and sacrificial film 5 can be carried out by sputtering, vapor deposition, or pulsed laser deposition (PLD), etc. The following describes how to deposit the multilayer film 3, mixed film 4, and sacrificial film 5 using the sputtering method.

[0068] In the sputtering method, first, the substrate 2 is placed in the sputtering apparatus. Next, a multilayer film 3 is formed on the first main surface 2a of the substrate 2 by alternately stacking a high refractive index film 6 and a low refractive index film 7 in that order.

[0069] The high refractive index film 6 can be deposited, for example, using a target made of the material constituting the high refractive index film 6, and can be carried out using an inert gas such as argon gas and oxygen gas as carrier gases. In this case, the flow rate of argon gas can be, for example, 500 sccm or more and 2000 sccm or less. The flow rate of oxygen gas can be, for example, 150 sccm or more and 600 sccm or less. The power applied during sputtering can be, for example, 5 kW or more and 15 kW or less, and the pressure inside the apparatus can be, for example, 0.1 Pa or more and 0.6 Pa or less. If the high refractive index film 6 is a nitride such as silicon nitride or aluminum nitride, nitrogen gas can be used as the carrier gas instead of oxygen gas. In this case, the flow rate of nitrogen gas can be, for example, 150 sccm or more and 600 sccm or less.

[0070] The low refractive index film 7 can be deposited, for example, using a target made of the material constituting the low refractive index film 7, and can be carried out using an inert gas such as argon gas and oxygen gas as carrier gases. In this case, the flow rate of argon gas can be, for example, 500 sccm or more and 2000 sccm or less. The flow rate of oxygen gas can be, for example, 150 sccm or more and 600 sccm or less. Furthermore, the power applied during sputtering can be, for example, 5 kW or more and 15 kW or less, and the pressure inside the apparatus can be, for example, 0.1 Pa or more and 0.6 Pa or less.

[0071] Next, a mixed film 4 is deposited on the main surface 3a of the multilayer film 3. The deposition of the mixed film 4 can be carried out using both a target made of the material constituting the high refractive index component and a target made of the material constituting the low refractive index component. In this case, an inert gas such as argon gas and oxygen gas can be used as the carrier gas. The flow rate of the argon gas can be, for example, 500 sccm or more and 2000 sccm or less. The flow rate of the oxygen gas can be, for example, 150 sccm or more and 600 sccm or less. The pressure inside the apparatus during sputtering can be, for example, 0.1 Pa or more and 0.6 Pa or less.

[0072] The applied power (film deposition power) to the target of the material constituting the high refractive index component is preferably 0.5 kW or more, more preferably 1.0 kW or more, preferably 3.0 kW or less, and more preferably 2.5 kW or less. The film deposition rate during film deposition of the material constituting the high refractive index component is preferably 0.01 nm / s or more, more preferably 0.015 nm / s or more, preferably 0.20 nm / s or less, and more preferably 0.15 nm / s or less.

[0073] The applied power (deposition power) to the target material constituting the low refractive index component is preferably 1.0 kW or more, more preferably 2.0 kW or more, preferably 4.0 kW or less, and more preferably 3.5 kW or less. The deposition rate during film formation of the material constituting the low refractive index component is preferably 0.01 nm / s or more, more preferably 0.015 nm / s or more, preferably 0.20 nm / s or less, and more preferably 0.15 nm / s or less.

[0074] When depositing the mixed film 4, for example, the applied power when sputtering using a target made of a material constituting the high refractive index component may be kept constant from the start to the end of the deposition of the mixed film 4, or the applied power may be gradually increased, or the applied power may be gradually decreased. When the applied power is kept constant from the start to the end of the deposition of the mixed film 4, the concentration of the high refractive index component in the thickness direction of the mixed film 4 can be kept approximately constant. When the applied power is gradually increased during deposition, the content of the high refractive index component can be increased in the resulting mixed film 4 from the multilayer film 3 side to the sacrificial film 5 side in the thickness direction. When the applied power is gradually decreased during deposition, the content of the high refractive index component can be decreased in the resulting mixed film 4 from the multilayer film 3 side to the sacrificial film 5 side in the thickness direction.

[0075] Furthermore, when sputtering using a target made of a material constituting the low refractive index component, the applied power may be kept constant from the start to the end of film formation of the mixed film 4, or the applied power may be gradually decreased, or the applied power may be gradually increased. When the applied power is kept constant from the start to the end of film formation of the mixed film 4, the concentration of the low refractive index component in the thickness direction of the mixed film 4 can be kept approximately constant. When the applied power is gradually decreased during film formation, the content of the low refractive index component can be increased from the sacrificial film 5 side to the multilayer film 3 side in the thickness direction. When the applied power is gradually increased during film formation, the content of the low refractive index component can be decreased from the sacrificial film 5 side to the multilayer film 3 side in the thickness direction.

[0076] Next, a sacrificial film 5 is deposited on the main surface 4a of the mixed film 4. This allows for the creation of a dielectric multilayer substrate 1. The sacrificial film 5 can be deposited using, for example, a silicon target, and an inert gas such as argon gas and oxygen gas can be used as carrier gases. In this case, the flow rate of the argon gas can be, for example, 500 sccm or more and 2000 sccm or less. The flow rate of the oxygen gas can be, for example, 150 sccm or more and 600 sccm or less. The power applied during sputtering can be, for example, 5 kW or more and 15 kW or less, and the pressure inside the apparatus can be, for example, 0.1 Pa or more and 0.6 Pa or less.

[0077] In the manufacturing method of this embodiment, a mixed film 4 can be formed as the outermost layer beneath the sacrificial film 5, which includes a high refractive index component with a relatively high refractive index and a low refractive index component with a relatively low refractive index. Therefore, even when subjected to alkaline cleaning, a dielectric multilayer film substrate 1 can be obtained that has the desired optical properties.

[0078] [Substrate with optical multilayer film] Figure 2 is a schematic cross-sectional view showing a substrate with an optical multilayer film according to one embodiment of the present invention. As shown in Figure 2, in the substrate 10 with an optical multilayer film, the sacrificial film 5 of the dielectric multilayer film substrate 1 shown in Figure 1 has been removed.

[0079] The optical multilayer film substrate 10 can be manufactured by performing alkaline cleaning on the dielectric multilayer film substrate 1 to remove the sacrificial film 5. Alkaline cleaning can be performed, for example, by immersing the dielectric multilayer film substrate 1 in an aqueous sodium hydroxide solution. The concentration of the aqueous sodium hydroxide solution can be, for example, 2% by mass or more and 5% by mass or less. The temperature of the aqueous sodium hydroxide solution can be, for example, 40°C or more and 80°C or less. The immersion time of the dielectric multilayer film substrate 1 in the aqueous sodium hydroxide solution can be, for example, 5 minutes or more and 60 minutes or less.

[0080] Since the optical multilayer film substrate 10 is obtained by removing the sacrificial film 5 from the dielectric multilayer film substrate 1, the outermost layer is composed of the mixed film 4 described above, and thus the desired optical properties can be obtained. Of course, in the optical multilayer film substrate 10, the structure and materials of the substrate 2 and the multilayer film 3 can also be the same as those of the dielectric multilayer film substrate 1 described above. Furthermore, since the outermost layer of the optical multilayer film substrate 10 is composed of the mixed film 4 described above, it is possible to design a film with the desired optical properties even when the optical multilayer film substrate 10 is subjected to further alkaline cleaning.

[0081] For example, in the optical multilayer film-coated substrate 10, the light transmittance at a thickness of 0.4 mm and a wavelength of 450 nm to 700 nm can be set to 99% or more and 100% or less.

[0082] The present invention will be described in more detail below based on specific examples. The present invention is not limited in any way to the following examples, and can be implemented with appropriate modifications without changing its essence.

[0083] (Examples 1-6 and Comparative Examples) First, a glass substrate (manufactured by Nippon Electric Glass Co., Ltd., OA-10G, 1.1 mm thick) was prepared as the substrate. Next, a multilayer film was deposited on one main surface of the prepared substrate by sputtering. Specifically, first, the substrate was placed in the sputtering apparatus. Next, using argon gas and oxygen gas as carrier gases, a niobium target was sputtered to deposit a niobium oxide film (Nb2O5 film) on one main surface of the substrate. At this time, the flow rate of argon gas was set to 1000 sccm, the flow rate of oxygen gas to 420 sccm, the target applied power (deposition power) to 10 kW, and the pressure inside the apparatus to 0.3 Pa. Next, using argon gas and oxygen gas as carrier gases, a silicon target was sputtered to deposit a silicon oxide film (SiO2 film) on the Nb2O5 film. In this process, the argon gas flow rate was set to 1000 sccm, the oxygen gas flow rate to 420 sccm, the target applied power (film deposition power) to 8 kW, and the pressure inside the apparatus to 0.3 Pa. By repeating this operation, a multilayer film was formed on one main surface of the substrate, in which Nb2O5 films and SiO2 films were alternately stacked one layer at a time.

[0084] Next, a mixed film containing tantalum oxide (Ta2O5), a high refractive index component with a relatively high refractive index, and silicon oxide (SiO2), a low refractive index component with a relatively low refractive index, was deposited on the main surface opposite to the multilayer substrate by sputtering to obtain a film-coated substrate. In this process, argon gas and oxygen gas were used as carrier gases, and the tantalum target and silicon target were sputtered to deposit the mixed film on the main surface of the multilayer. The flow rate of argon gas was set to 1000 sccm, the flow rate of oxygen gas to 420 sccm, and the pressure inside the apparatus was set to 0.3 Pa. In the comparative example, a tantalum oxide (Ta2O5) film was deposited instead of a mixed film.

[0085] When forming the mixed films of Examples 1-6 and the Comparative Examples, the applied power to the tantalum and silicon targets (deposition power), and the deposition rates for tantalum and silicon were set as shown in Table 1 below. Furthermore, the content of tantalum oxide (Ta2O5) (unit: mass%), silicon oxide (SiO2) (unit: mass%), the ratio of tantalum oxide (Ta2O5) content (unit: mass%) to silicon oxide (SiO2) content (Ta2O5 content / SiO2 content (mass ratio)), the refractive index at a wavelength of 550 nm, and the film thickness (thickness) of the mixed films obtained in each example and comparative example are as shown in Table 1 below. The content of SiO2 and Ta2O5 in the mixed films was measured using a scanning transmission electron microscope (STEM-EDX (Scanning Transmission Electron Microscope - Energy Dispersive X-ray Spectroscopy), Hitachi High-Tech Corporation, model number "HD-2700"). Furthermore, the refractive index of the mixed film at a wavelength of 550 nm was measured by molecular ellipsometry (JA Woollam Japan, M-2000).

[0086] Next, a silicon oxide sacrificial film was formed by sputtering to obtain a dielectric multilayer substrate. During this process, the argon gas flow rate was set to 1000 sccm, the oxygen gas flow rate to 420 sccm, the target power (deposition power) to 8 kW, and the pressure inside the apparatus to 0.3 Pa. Tables 2-8 show the film configurations for Examples 1-6 and the comparative example.

[0087] [Table 1]

[0088] [Table 2]

[0089] [Table 3]

[0090] [Table 4]

[0091] [Table 5]

[0092] [Table 6]

[0093] [Table 7]

[0094] [Table 8]

[0095] (Reference examples 1~6) A glass substrate (manufactured by Nippon Electric Glass Co., Ltd., OA-10G, 1.1 mm thick) was prepared as the substrate. A mixed film containing tantalum oxide (Ta2O5), a high refractive index component with a relatively high refractive index, and silicon oxide (SiO2), a low refractive index component with a relatively low refractive index, or a film consisting of either tantalum oxide (Ta2O5) or silicon oxide (SiO2) as a single component, was deposited on the substrate to obtain a film-coated substrate. In this process, argon gas and oxygen gas were used as carrier gases, and the tantalum target and silicon target were sputtered to deposit the mixed film on the substrate. The flow rate of argon gas was set to 1000 sccm, the flow rate of oxygen gas to 420 sccm, and the pressure inside the apparatus was set to 0.3 Pa.

[0096] When depositing the mixed films for each reference example, the applied power to the tantalum and silicon targets (deposition power), as well as the deposition rates for tantalum and silicon, were set as shown in Table 1. Furthermore, the content of tantalum oxide (Ta2O5) (unit: mass%), silicon oxide (SiO2) (unit: mass%), the ratio of tantalum oxide (Ta2O5) content (unit: mass%) to silicon oxide (SiO2) content (Ta2O5 content / SiO2 content), the refractive index at a wavelength of 550 nm, and the film thickness (thickness) of the mixed films obtained in each reference example are shown in Table 1.

[0097] [Rating 1] The dielectric multilayer film substrates obtained in each example and comparative example were evaluated as follows.

[0098] (Alkaline immersion test) Alkaline immersion tests were performed in each example and comparative example. In the alkaline immersion test, the obtained dielectric multilayer film-coated substrates were immersed for 10 minutes in a 3.0% by mass sodium hydroxide aqueous solution at a temperature of 60°C.

[0099] (Measurement of light transmittance) The light transmittance of the film-coated substrates of each example and comparative example was measured after the alkaline immersion test. For the light transmittance measurement, a spectrophotometer (Hitachi High-Tech Corporation, U-4000) was used, with an incident angle of 0°, and the light transmission spectrum of the film-coated substrate in the wavelength range of 350 nm to 850 nm was measured.

[0100] Figure 3 shows the light transmission spectra of the film-coated substrates after the alkali immersion test obtained in each example and comparative example.

[0101] As shown in Figure 3, the film-coated substrates obtained in Examples 1 to 6 exhibit high light transmittance of over 99% in the wavelength range of 450 nm to 700 nm. In contrast, the film-coated substrates in the comparative examples, which used a film consisting only of tantalum oxide (Ta2O5) as the outermost layer, do not exhibit sufficient light transmittance.

[0102] Thus, it was confirmed that the film-coated substrates obtained in Examples 1 to 6 retained high optical properties even after alkaline cleaning.

[0103] Furthermore, when the film-coated substrates obtained in Examples 1 to 6 were subjected to compositional analysis of the outermost layer surface of the multilayer film using a scanning transmission electron microscope (STEM-EDX (Scanning Transmission Electron Microscope - Energy Dispersive X-ray Spectroscopy), Hitachi High-Tech Corporation, part number "HD-2700"), it was confirmed that the outermost layer was a mixed film containing tantalum oxide (Ta2O5) and silicon oxide (SiO2), thus confirming that optical multilayer film-coated substrates were obtained.

[0104] Furthermore, the obtained optical multilayer film-coated substrates were subjected to an additional 5-minute alkaline immersion test. Specifically, in the additional alkaline immersion test, the obtained optical multilayer film-coated substrates were immersed for 5 minutes in a 3.0% by mass sodium hydroxide aqueous solution at 60°C.

[0105] When the optical multilayer film substrates of Examples 1 to 6 were subjected to light transmittance measurements using the same method as described above after the additional alkaline immersion test, it was confirmed that even the optical multilayer film substrates with a mixed film as the outermost layer exhibited high optical properties, similar to those before the additional alkaline immersion test.

[0106] [Rating 2] The following evaluations were performed on the film-coated substrates obtained from each reference example.

[0107] (Alkaline immersion test) Alkaline immersion tests were performed on the film-coated substrates obtained in each reference example. In the alkaline immersion test, the obtained film-coated substrates were immersed in a 3.0% by mass sodium hydroxide aqueous solution at 60°C for a predetermined time, and the amount of dissolved material after immersion was determined. In the alkaline immersion test, the immersion time was set to 10 minutes, 20 minutes, 30 minutes, 40 minutes, and 50 minutes, and the amount of dissolved material after immersion was determined for each immersion time. Furthermore, the amount of dissolved material after immersion was determined from the change in film thickness before and after alkaline immersion.

[0108] Figure 4 shows the results of the alkali immersion test of the film-coated substrates obtained for each reference example. In Figure 4, the vertical axis represents the amount of film dissolved, and the horizontal axis represents the immersion time of the film-coated substrate in alkali.

[0109] As shown in Figure 4, in Reference Example 5, the film-coated substrate, in which the film consists only of a low refractive index component, showed a large amount of solubility in alkali. In contrast, in Reference Examples 1-4, where the film contains both a high refractive index component and a low refractive index component, and in Reference Example 6, where the film consists only of a high refractive index component, the amount of solubility in alkali was significantly reduced. [Explanation of Symbols]

[0110] 1… Dielectric multilayer substrate 2… Circuit board 2a...First main surface 2b...Second main surface 3…Multilayer film 3a…main surface 4…Mixed membrane 4a... Main surface 5…Sacrificial membrane 6…High refractive index film 7... Low refractive index film 10…Substrate with optical multilayer film

Claims

1. circuit board and A multilayer film provided on the substrate, having a portion in which a high refractive index film with a relatively high refractive index and a low refractive index film with a relatively low refractive index are alternately stacked, A mixed film provided on the aforementioned multilayer film, comprising a high refractive index component with a relatively high refractive index and a low refractive index component with a relatively low refractive index, A sacrificial film is provided on the mixed film, A substrate with a dielectric multilayer film, comprising the above features.

2. The dielectric multilayer film substrate according to claim 1, wherein the mixed film comprises at least one selected from the group consisting of tantalum oxide, hafnium oxide, titanium oxide, and zirconium oxide.

3. The dielectric multilayer film substrate according to claim 2, wherein the high refractive index component in the mixed film is tantalum oxide.

4. The dielectric multilayer film substrate according to claim 3, wherein the low refractive index component in the mixed film is silicon oxide.

5. A dielectric multilayer film substrate according to any one of claims 1 to 4, wherein the ratio of the content of the high refractive index component to the low refractive index component (high refractive index component / low refractive index component) in the mixed film is 0.03 or more and 9.0 or less by mass ratio.

6. A dielectric multilayer film substrate according to any one of claims 1 to 4, wherein the refractive index of the mixed film at a wavelength of 550 nm is 1.3 or more and 2.1 or less.

7. A dielectric multilayer film substrate according to any one of claims 1 to 4, wherein the sacrificial film contains silicon oxide.

8. A dielectric multilayer film substrate according to any one of claims 1 to 4, wherein the low refractive index film in the multilayer film contains silicon oxide.

9. A dielectric multilayer film substrate according to any one of claims 1 to 4, wherein the multilayer film comprises at least one selected from the group consisting of niobium oxide, titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silicon nitride, aluminum oxide, and aluminum nitride.

10. A step of forming a multilayer film on a substrate, having a portion in which a high refractive index film with a relatively high refractive index and a low refractive index film with a relatively low refractive index are alternately stacked. A step of forming a mixed film on the multilayer film, which includes a high refractive index component with a relatively high refractive index and a low refractive index component with a relatively low refractive index. The steps include forming a sacrificial film on the mixed film, A method for manufacturing a dielectric multilayer film substrate, comprising the features described above.

11. A step of preparing a dielectric multilayer film substrate according to any one of claims 1 to 4, The process involves alkaline cleaning the dielectric multilayer film-coated substrate to remove the sacrificial film, A method for manufacturing a substrate with an optical multilayer film, comprising the features described above.

12. circuit board and A multilayer film provided on the substrate, having a portion in which a high refractive index film with a relatively high refractive index and a low refractive index film with a relatively low refractive index are alternately stacked, A mixed film provided on the aforementioned multilayer film, comprising a high refractive index component with a relatively high refractive index and a low refractive index component with a relatively low refractive index, A substrate with an optical multilayer film, comprising the above features.

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