JPWO2019151431A1 - Manufacturing method of transparent substrate with film - Google Patents

Abstract

The present invention is a transparent substrate with a film capable of producing a transparent substrate with a film having a low light absorption rate, particularly a low visible light absorption rate, even if it is a transparent substrate with a film having a metal layer and a dielectric layer. An object is to provide a manufacturing method. A metal layer forming step of forming a metal layer 2 on a transparent substrate 1 and a protective metal layer forming of the metal layer 2 on the opposite side of the transparent substrate 1 in contact with the metal layer 2 to form a protective metal layer 5. It is characterized by comprising a step and a dielectric layer forming step of forming the dielectric layer 4 in contact with the protective metal layer 5 on the opposite side of the protective metal layer 5 from the transparent substrate 1 by a sputtering method. To do.

Description

The present invention relates to a method for manufacturing a transparent substrate with a film used for a cover member, a half mirror, a bandpass filter, and the like.

Transparent substrates with a film are widely used in various fields.
For example, as in Patent Document 1, there is an observation system (transparent substrate with a film) having a half mirror composed of a metal film and a dielectric film. In recent years, as the optical characteristics of transparent substrates with films have improved, it has become necessary to control the film thickness of the films constituting the transparent substrates with films with higher accuracy.

Japanese Unexamined Patent Publication No. 11-249067

By the way, when a transparent substrate with a film having a metal film and a dielectric film is produced by using a sputtering method, which can control the film thickness with higher accuracy than the vacuum vapor deposition method described in Patent Document 1, the metal film is used. When a dielectric film is formed after the film formation, there is a problem that the metal film is denatured and the light absorption rate changes significantly.

Therefore, according to the present invention, even if it is a transparent substrate with a film having a metal layer and a dielectric layer, it is possible to produce a transparent substrate with a film whose light absorption rate, particularly visible light absorption rate is controlled. An object of the present invention is to provide a method for manufacturing a transparent substrate.

The method for manufacturing a transparent substrate with a film according to the present invention, which was devised to solve the above problems, is such that a metal layer forming step of forming a metal layer on the transparent substrate and the metal layer on the opposite side of the transparent substrate. A dielectric layer is formed in contact with the protective metal layer on the opposite side of the protective metal layer from the transparent substrate by a protective metal layer forming step of forming the protective metal layer in contact with the metal layer and a sputtering method. It is characterized by including a dielectric layer forming step.

According to such a configuration, deterioration of the metal layer can be suppressed by the protective metal layer provided in contact with the metal layer. As a result, the absorption rate of visible light of the transparent substrate with a film can be efficiently controlled.

In the above configuration, the thickness of the protective metal layer is preferably 2 to 15 nm. According to such a configuration, it is possible to suppress the deterioration of the metal layer and reduce the visible light absorption rate of the light of the dielectric layer. As a result, the absorption rate of visible light of the transparent substrate with a film can be efficiently controlled.

In the above configuration, it is preferable that the protective metal layer is made of silicon or aluminum. According to such a configuration, it is possible to suppress the deterioration of the metal layer and reduce the visible light absorption rate of the light of the dielectric layer. As a result, the absorption rate of visible light of the transparent substrate with a film can be efficiently controlled.

In the above configuration, it is preferable that the sputtering method is a reactive sputtering method. According to such a configuration, it is possible to improve the productivity of the dielectric layer and to control the film thickness with high accuracy.

In the above configuration, it is preferable that the protective metal layer is reacted in the dielectric layer forming step to form a protective layer made of any one of a metal oxide, a metal nitride and a metal oxynitride. As a result, the absorption rate of visible light of the transparent substrate with a film can be efficiently controlled.

In the above configuration, it is preferable that the metal layer is made of silver. As a result, the absorption rate of visible light of the transparent substrate with a film can be efficiently reduced.

In the above configuration, it is preferable that the metal layer is made of tin. As a result, the absorption rate of visible light of the transparent substrate with a film can be efficiently increased.

In the above configuration, a protective oxide layer composed of silicon oxide or aluminum oxide is formed on the transparent substrate before the metal layer forming step, and is in contact with the protective oxide layer in the metal layer forming step. It is preferable to form the metal layer. As a result, the visible light absorption rate of the transparent substrate with a film can be efficiently increased, and the wavelength dependence of the visible light absorption rate in the entire visible light range can be reduced.

According to the present invention, it is possible to provide a transparent substrate with a film in which the absorption rate of light, particularly the absorption rate of visible light is controlled.

It is sectional drawing which shows the transparent substrate with a film which concerns on one Embodiment of this invention. It is a flowchart which shows the manufacturing process of the transparent substrate with a film which concerns on one Embodiment of this invention. It is sectional drawing which shows how the transparent substrate with a film which concerns on one Embodiment of this invention is formed. It is a graph which shows the transmission / reflection / absorption spectrum of the transparent substrate with a film which concerns on Example 1. FIG. It is a graph which shows the transmission / reflection / absorption spectrum of the transparent substrate with a film which concerns on Comparative Example 1. It is a graph which shows the transmission / reflection / absorption spectrum of the transparent substrate with a film which concerns on Example 2. FIG. It is a graph which shows the transmission / reflection / absorption spectrum of the transparent substrate with a film which concerns on Example 3. FIG. It is a graph which shows the transmission / reflection / absorption spectrum of the transparent substrate with a film which concerns on Comparative Example 2.

Hereinafter, embodiments for carrying out the present invention will be described, but the present invention is not limited to the following embodiments, and is based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that the following embodiments are also modified or improved as appropriate within the scope of the present invention.

FIG. 1 is a cross-sectional view showing an example of an embodiment of the transparent substrate 10 with a film of the present invention. The transparent substrate 10 with a film shown in FIG. 1 protects the transparent substrate 1, the metal layer 2 arranged on one main surface of the transparent substrate 1, and the protective layer 3 arranged in contact with the metal layer 2. The dielectric layer 4 arranged on the layer 3 is a main component.

The transparent substrate 1 is transparent and has mechanical strength to withstand the load received during the manufacture and use of the transparent substrate 10 with a film. Transparency means that visible light (400 nm to 700 nm) is transmitted by 80% or more on average. A glass or resin material is suitable for the transparent substrate 1. As the glass, for example, known glass such as non-alkali glass, aluminosilicate glass, soda-lime glass, and quartz glass can be used. Further, tempered glass such as chemically strengthened glass and crystallized glass such as LAS-based crystallized glass can also be used. The glass is preferably aluminosilicate glass, and the aluminosilicate glass is SiO ₂ : 50 to 80%, Al ₂ O ₃ : 5 to 25%, B ₂ O ₃ : 0 to 15 in mass%. %, Na ₂ O: 1 to 20%, K ₂ O: 0 to 10%, more preferably. Examples of the resin material include acrylic resins such as polymethyl methacrylate, polycarbonate resins, and epoxy resins. The transparent substrate 1 is preferably made of glass in that the transmittance of visible light does not easily decrease with time.

The transparent substrate 1 has a first main surface 1a and a second main surface 1b facing the first main surface 1a. The thickness of the transparent substrate 1 may be set in consideration of mechanical properties and the like, and is preferably in the range of 0.05 mm or more and 10 mm or less, for example.

A metal layer 2 is arranged on the first main surface 1a of the transparent substrate 1. The metal layer 2 is a layer containing a metal such as silver, tin, indium, nickel, molybdenum, and copper as a main component. Here, the metal layer 2 containing silver, nickel, molybdenum, and copper as main components as materials is a low light absorption metal layer having a low visible light absorption rate, and the metal layer 2 containing tin and indium as main components as materials is , A high light absorbing metal layer with a high visible light absorption rate.

The mass ratio of the metal in the low light absorption metal layer is preferably 95% by mass or more, more preferably 97% by mass or more, and further preferably 99% by mass or more. If the mass ratio of the metal in the low light absorption metal layer is too low, the visible light absorption rate tends to be high. The low light absorbing metal layer 2 may contain, for example, europium, calcium, praseodymium, samarium, magnesium, terbium, gadolinium, neodymium, lanthanum, cerium, etc., in addition to silver, nickel, molybdenum, and copper.

The low light absorption metal layer has a very low visible light absorption rate. Therefore, the absorption rate of visible light of the transparent substrate 10 with a film can be efficiently reduced. Since the low light absorption metal layer contains a large amount of metal oxide such as silver oxide, the absorption rate of visible light in the low light absorption metal layer becomes high. Therefore, it is more preferable that the low light absorption metal layer does not contain a metal oxide.

The mass ratio of the metal in the high light absorption metal layer is preferably 95% by mass or more, more preferably 97% by mass or more, and further preferably 99% by mass or more. If the mass ratio of the metal in the high light absorption metal layer is too high, the visible light absorption rate tends to be high.

The high light absorption metal layer has a very high visible light absorption rate. Therefore, the absorption rate of visible light of the transparent substrate 10 with a film can be efficiently increased. Since the high light absorption metal layer contains a large amount of metal oxides such as tin oxide and indium oxide, the absorption rate of visible light in the high light absorption metal layer is lowered. Therefore, it is more preferable that the high light absorption metal layer does not contain a metal oxide.

The thickness of the metal layer 2 is preferably 1 to 30 nm. When the thickness of the metal layer 2 is 1 nm or more, the effect of reducing or increasing the absorption rate of visible light is efficiently exhibited. When the thickness of the metal layer 2 is 30 nm or less, the reflection of visible light by the metal layer 2 is suppressed. The thickness of the metal layer 2 is more preferably 5 to 10 nm.

The protective layer 3 is composed of a metal oxide, a metal nitride, or a metal oxynitride.

Silicon or aluminum is preferable as the metal constituting the metal oxide, the metal nitride, and the metal oxynitride. By using silicon or aluminum, energy such as plasma is less likely to be transmitted to the metal layer 2, and even after silicon or aluminum is oxidized or nitrided, oxygen or nitrogen bonded to silicon or aluminum is less likely to be transmitted to the metal layer 2. It is possible to suppress an increase in the light absorption rate of the metal layer 2. As the metal constituting the metal oxide, the metal nitride, and the metal oxynitride, silicon, which is easily used as a dielectric multilayer film, is particularly preferable.

The thickness of the protective layer 3 is preferably 1 to 20 nm. When the thickness of the protective layer 3 is 1 nm or more, it is possible to efficiently suppress the direct application of energy such as plasma. When the thickness of the protective layer 3 is 20 nm or less, the protective layer 3 can be formed quickly. The thickness of the protective layer 3 is more preferably 2 to 10 nm.

The dielectric layer 4 is composed of a single-layer dielectric film or a plurality of layers of dielectric multilayer films. Examples of the dielectric layer 4 include a dielectric multilayer film in which high refractive index layers and low refractive index layers are alternately laminated. Examples of the high refractive index layer include titanium oxide, niobium oxide, lanthanum oxide, tantalum oxide, zircon oxide, silicon nitride and the like. Examples of the low refractive index layer include silicon oxide, aluminum oxide, magnesium fluoride and the like. The thickness, number of layers, and material of the dielectric multilayer film may be designed according to the characteristics required for the transparent substrate 10 with a film.

Further, a dielectric layer different from the dielectric layer 4 may be provided between the transparent substrate 1 and the metal layer 2. The thickness, number of layers, and material of the dielectric multilayer film may be designed according to the characteristics required for the transparent substrate 10 with a film.

Applications of the transparent substrate 10 with a film include a cover member, a half mirror, a bandpass filter, and the like.

Hereinafter, a method for manufacturing a transparent substrate with a film according to the present embodiment will be described with reference to FIGS.

As shown in FIG. 2, the method for manufacturing a transparent substrate with a film includes a metal layer forming step S11, a protective metal layer forming step S12, and a dielectric layer forming step S13.

(Metal layer forming process)
In the metal layer forming step S11, the metal layer 2 can be formed by, for example, a physical vapor deposition method such as a sputtering method or a vacuum vapor deposition method, or a plating method. In order to form the metal layer 2 having a film thickness of 1 to 30 nm by controlling the film thickness with high accuracy, the sputtering method is preferable.

Next, an example of a method for forming the metal layer 2 by the sputtering method will be described.
First, the transparent substrate 1 is prepared. Subsequently, the prepared transparent substrate 1 is set in the sputtering apparatus. As the target of the sputtering apparatus, a metal target made of metal or a metal alloy is prepared. When silver is used as the metal layer 2, the silver alloy contains at least one of europium, copper, calcium, praseodymium, samarium, magnesium, terbium, gadorium, neodymium, lantern, and cerium in a total of 2% by mass or less. However, it is preferable that the balance has a composition of silver and unavoidable impurities.

Next, an inert gas is introduced into the sputtering apparatus to sputter the metal target, and a metal layer 2 made of a metal or a metal alloy is formed on the first main surface 1a of the transparent substrate 1 to form a metal layer 2 (FIG. 3). Obtain a substrate with a metal layer as shown in a). Argon gas can be used as the inert gas. It is desirable that the inert gas is introduced after the inside of the sputtering apparatus is exhausted by a vacuum pump or the like.

When tin or indium, which is more easily oxidized or nitrided than silver, is used as the metal target to form a metal layer 2, the metal layer 2 is formed from silicon oxide or aluminum oxide on the first main surface 1a of the transparent substrate 1 in advance. It is preferable to form a protective oxide layer to be formed and to form a metal layer 2 in contact with the protective oxide layer. By forming the protective oxide layer, oxidation and nitriding of the metal layer 2 can be further suppressed.

(Protective metal layer forming process)
In the protective metal layer forming step S12, the protective metal layer 5 can be formed by a physical vapor deposition method such as a sputtering method or a vacuum vapor deposition method. The thickness of the protective metal layer 5 is preferably 2 to 15 nm. In order to form the protective metal layer 5 having a film thickness of 2 to 15 nm accurately and stably, the sputtering method is preferable.

An example of a method for forming the protective metal layer 5 by the sputtering method will be described.
The substrate with the metal layer is set in the sputtering apparatus. As a target of the sputtering apparatus, a metal target such as silicon, aluminum, or zirconium is prepared. It is preferable to use a metal target made of silicon or aluminum, and it is particularly preferable to use a silicon target made of silicon. Metals such as aluminum and boron may be doped in a range not exceeding 10 wt% in order to increase the conductivity of the silicon target.

By introducing an inert gas into the sputtering apparatus and sputtering the silicon target, a protective metal layer 5 made of silicon is formed to obtain a substrate with a protective metal layer as shown in FIG. 3 (b). Argon gas can be used as the inert gas. It is desirable that the inert gas is introduced after the inside of the sputtering apparatus is exhausted by a vacuum pump or the like.

(Dielectric layer forming process)
The dielectric layer 4 is formed by a sputtering method. The dielectric layer 4 can be formed accurately and stably by the sputtering method. Further, among the sputtering methods, the reactive sputtering method such as the RAS (Radical Assisted Sputtering) method is particularly preferable because the film formation rate of the dielectric layer 4 is high and the productivity is excellent.

An example of a method for forming the dielectric layer 4 by the reactive sputtering method will be described.
The substrate with the protective metal layer is set in the sputtering apparatus. As the target of the sputtering apparatus, a metal target such as silicon, aluminum, tantalum, niobium, titanium, hafnium, or zirconium can be used.

A mixed gas of an inert gas and an active gas is introduced into the sputtering apparatus to sputter a predetermined target to form a layer composed of the predetermined target component on a substrate with a protective metal layer, and the layer is plasma. The dielectric layer 4 is formed by reacting with an active gas activated by the above. Argon gas can be used as the inert gas. Further, as the active gas, oxygen gas, nitrogen gas, hydrogen gas, or a mixed gas thereof can be used. It is desirable that the mixed gas of the inert gas and the active gas is introduced after the inside of the sputtering apparatus is exhausted by a vacuum pump or the like. The mixing ratio of the inert gas and the active gas (inert gas: active gas) is not particularly limited, and can be, for example, in the range of 2: 1 to 8: 1.

Here, in the dielectric layer forming step, when a predetermined target component to be the dielectric layer reacts with the active gas activated by plasma or the like, the protective metal layer 5 also becomes the active gas activated by plasma or the like. It reacts and the protective layer 3 is formed. At this time, if the thickness of the protective metal layer 5 is too small, the protective effect of the protective metal layer 5 cannot be obtained, and the metal layer 2 reacts with the active gas to oxidize or nitride the metal layer 2. On the other hand, if the thickness of the protective metal layer 3 is too large, the reaction between the protective metal layer 5 and the active gas becomes insufficient, and the light absorption rate of the protective layer 3 becomes high. Therefore, the thickness of the protective metal layer 5 is preferably 2 to 15 nm.

When a transition metal such as niobium is used as the metal component of the protective metal layer 5, the reaction between the metal layer 2 and the active gas may occur before the reaction between the protective metal layer 5 and the active gas is completed. , Not preferable.

Further, when the protective metal layer 5 is not provided, there is a problem that the metal layer 2 reacts with the active gas to increase the light absorption rate of the metal layer 2.

The transparent substrate 10 with a film is preferably a cover member. The cover member has, for example, a moderately high absorption rate in visible light (for example, an average absorption rate of 15 to 30%) and a small wavelength dependence of the absorption rate in the entire visible light range (for example, absorption). The difference between the maximum and minimum rates is 10% or less). By using a high light absorbing metal layer as the metal layer 2 of the present invention, a cover member satisfying the above requirements can be obtained.

It is more preferable that the cover member is provided with a dielectric layer between the transparent substrate 1 and the metal layer 2 because the optical characteristics can be controlled more strictly.

Further, the transparent substrate 10 with a film is preferably a half mirror. Half mirrors are required to have a low visible light absorption rate. By using a low light absorption metal layer as the metal layer 2 of the present invention, a half mirror satisfying the above requirements can be obtained.

It is more preferable to provide a dielectric layer between the transparent substrate 1 and the metal layer 2 because the optical characteristics of the half mirror can be controlled more strictly.

Further, the transparent substrate 10 with a film is preferably a bandpass filter. The metal layer 2 made of silver has a very low average refractive index of visible light of 0.5 or less as compared with the dielectric layer 4. Therefore, even if the incident angle of the visible light incident from the dielectric layer 4 side is very small, the visible light is totally reflected. That is, it is suitable as a bandpass filter that transmits only visible light having an incident angle other than approximately 0 °.

Next, Examples and Comparative Examples will be described.
(Example 1)
First, as a transparent substrate, a niobium oxide (Nb ₂ O ₅ ) film having a thickness of 24.6 nm and a silicon oxide (SiO ₂ ) having a thickness of 31.2 nm as a dielectric layer are placed on a quartz glass substrate having a thickness of 1.0 mm. A film, an Nb ₂ O ₅ film having a thickness of 53.3 nm, and a SiO ₂ film having a thickness of 10 nm were formed in this order by a sputtering method. A load-lock type reactive sputtering apparatus was used to form each film by the sputtering method.

Subsequently, as a metal layer forming step, a metal layer made of silver having a thickness of 20 nm was formed using a load-lock type reactive sputtering apparatus to obtain a substrate with a metal layer. At this time, the flow rate of argon gas was set to 400 sccm. The film forming pressure of the metal layer was 0.1 Pa.

Next, as a protective metal layer forming step, the silicon target is sputtered while maintaining the same flow rate of argon gas so that the protective metal layer made of silicon has a thickness of 5 nm on the metal layer. Formed. At this time, the film forming pressure of the protective metal layer was set to 0.4 Pa.

Next, as a dielectric layer forming step, a mixed gas of argon gas and oxygen gas is introduced into the sputtering apparatus to sputter the niobium target, and Nb ₂ O ₅ having a thickness of 48.4 nm is placed on the protective metal layer. A film was formed. At this time, the flow rate of argon gas was set to 500 sccm, and the flow rate of oxygen gas was set to 200 sccm. The film formation pressure of the Nb ₂ O ₅ film was 0.4 Pa.

Next, a SiO ₂ film having a thickness of 80.0 nm was formed on the Nb ₂ O ₅ film by sputtering the silicon target while keeping the mixed gas of argon gas and oxygen gas at the same flow rate. , A transparent substrate with a film was obtained. At this time, the film formation pressure of the SiO ₂ film was set to 0.4 Pa.

In the dielectric layer forming step, a protective layer made of SiO ₂ was formed from a protective metal layer made of silicon.

(Comparative Example 1)
A transparent substrate with a film was produced in the same manner as in Example 1 except that the protective metal layer forming step was not performed.

The film configurations of Example 1 and Comparative Example 1 are shown in Table 1.

(Evaluation)
With respect to the transparent substrate with a film obtained in Example 1 and Comparative Example 1, the transmittance and reflectance were measured by Hitachi High-Tech Corporation under the trade name "U-4000". In addition, the absorption rate (Absorptance) was calculated and obtained by the formula (1).
Absorption rate (%) = 100-transmittance (%) -reflectance (%) ... (1)
The transmission, reflection, and absorption spectra of each are shown in FIGS. 4 and 5.

As shown in FIG. 4, the transparent substrate with a film of Example 1 had a low absorption rate of 10% or less in the wavelength range of visible light (400 nm to 700 nm). On the other hand, as shown in FIG. 5, the transparent substrate with a film of Comparative Example 1 had a high absorption rate of 10% or more at a wavelength of 485 nm or less. It is considered that a part of the metal layer made of silver is oxidized or colloidalized.

(Example 2)
First, as a transparent substrate, an Nb ₂ O ₅ film having a thickness of 5.3 nm and a thickness of 57 as a dielectric layer are placed on a chemically strengthened glass substrate (manufactured by Nippon Electric Glass Co., Ltd., T2X-1) having a thickness of 1.3 mm. A 1 nm SiO ₂ film, a 21.8 nm thick Nb ₂ O ₅ film, and a 19.5 nm thick SiO ₂ film were formed in this order by a sputtering method. A load-lock type reactive sputtering apparatus was used to form each film by the sputtering method.

Subsequently, as a metal layer forming step, a metal layer made of tin having a thickness of 6 nm was formed using a load-lock type reactive sputtering apparatus to obtain a substrate with a metal layer. At this time, the flow rate of argon gas was set to 500 sccm. The film forming pressure of the metal layer was 0.3 Pa.

Next, as a protective metal layer forming step, the silicon target is sputtered while maintaining the same flow rate of argon gas so that the protective metal layer made of silicon has a thickness of 2 nm on the metal layer. Formed. At this time, the film forming pressure of the protective metal layer was set to 0.3 Pa.

Next, after introducing a mixed gas of argon gas and oxygen gas into the sputtering apparatus, a silicon target is sputtered as a dielectric layer forming step, and a SiO ₂ film having a thickness of 8.8 nm is formed on the protective metal layer. A film was formed. At this time, the flow rate of argon gas was set to 500 sccm, and the flow rate of oxygen gas was set to 220 sccm. The film formation pressure of the SiO ₂ film was 0.3 Pa.

Next, an Nb ₂ O ₅ film having a thickness of 40.4 nm was formed on the SiO ₂ film by sputtering the niobium target while keeping the mixed gas of argon gas and oxygen gas at the same flow rate. .. At this time, the film forming pressure of the Nb ₂ O ₅ film was set to 0.3 Pa.

Next, a SiO ₂ film having a thickness of 93.2 nm was formed on the Nb ₂ O ₅ film by sputtering the silicon target while keeping the mixed gas of argon gas and oxygen gas at the same flow rate. , A transparent substrate with a film was obtained. At this time, the film formation pressure of the SiO ₂ film was set to 0.3 Pa.

In the dielectric layer forming step, a protective layer made of SiO ₂ was formed from a protective metal layer made of silicon.

(Example 3)
First, as a transparent substrate, an Nb ₂ O ₅ film having a thickness of 8.7 nm and a thickness of 53 as a dielectric layer are placed on a chemically strengthened glass substrate (manufactured by Nippon Electric Glass Co., Ltd., T2X-1) having a thickness of 1.3 mm. A SiO ₂ film having a thickness of .2 nm and an Nb ₂ O ₅ film having a thickness of 25.1 nm were formed in order by a sputtering method. A load-lock type reactive sputtering apparatus was used to form each film by the sputtering method.

Subsequently, as a metal layer forming step, a metal layer made of tin having a thickness of 6 nm was formed using a load-lock type reactive sputtering apparatus to obtain a substrate with a metal layer. At this time, the flow rate of argon gas was set to 500 sccm. The film forming pressure of the metal layer was 0.3 Pa.

Next, as a protective metal layer forming step, the silicon target is sputtered while maintaining the same flow rate of argon gas so that the protective metal layer made of silicon has a thickness of 2 nm on the metal layer. Formed. At this time, the film forming pressure of the protective metal layer was set to 0.3 Pa.

Next, after introducing a mixed gas of argon gas and oxygen gas into the sputtering apparatus, a silicon target is sputtered as a dielectric layer forming step, and a SiO ₂ film having a thickness of 9 nm is formed on the protective metal layer. did. At this time, the flow rate of argon gas was set to 500 sccm, and the flow rate of oxygen gas was set to 220 sccm. The film formation pressure of the SiO ₂ film was 0.3 Pa.

Next, an Nb ₂ O ₅ film having a thickness of 43.2 nm was formed on the SiO ₂ film by sputtering the niobium target while keeping the mixed gas of argon gas and oxygen gas at the same flow rate. .. At this time, the film forming pressure of the Nb ₂ O ₅ film was set to 0.3 Pa.

Next, a SiO ₂ film having a thickness of 99.2 nm was formed on the Nb ₂ O ₅ film by sputtering the silicon target while keeping the mixed gas of argon gas and oxygen gas at the same flow rate. , A transparent substrate with a film was obtained. At this time, the film formation pressure of the SiO ₂ film was set to 0.3 Pa.

In the dielectric layer forming step, a protective layer made of SiO ₂ was formed from a protective metal layer made of silicon.

(Comparative Example 2)
First, as a transparent substrate, an Nb ₂ O ₅ film having a thickness of 13.2 nm and a thickness of 32 as a dielectric layer are placed on a chemically strengthened glass substrate (manufactured by Nippon Electric Glass Co., Ltd., T2X-1) having a thickness of 1.3 mm. A 4.7 nm SiO ₂ film, a 107.3 nm thick Nb ₂ O ₅ film, and a 30.2 nm thick SiO ₂ film were formed in this order by a sputtering method. A load-lock type reactive sputtering apparatus was used to form each film by the sputtering method.

Subsequently, as a metal layer forming step, a metal layer made of tin having a thickness of 6 nm was formed using a load-lock type reactive sputtering apparatus to obtain a substrate with a metal layer. At this time, the flow rate of argon gas was set to 500 sccm. The film forming pressure of the metal layer was 0.3 Pa.

Next, after introducing a mixed gas of argon gas and oxygen gas into the sputtering apparatus without forming a protective metal layer, a silicon target is sputtered as a dielectric layer forming step to obtain a thickness on the metal layer. A 56.3 nm SiO ₂ film was formed to obtain a transparent substrate with a film. At this time, the film formation pressure of the SiO ₂ film was set to 0.3 Pa.

The film configurations of Examples 2, 3 and Comparative Example 2 are shown in Table 2.

As shown in FIG. 6, the transparent substrate with a film of Example 2 has an average absorption rate of 23% in the visible light wavelength range (400 nm to 700 nm), and the maximum and minimum absorption rates at each wavelength. The difference was 6%. Further, as shown in FIG. 7, the transparent substrate with a film of Example 3 has an average absorption rate of 15% in the visible light wavelength range (400 nm to 700 nm), which is the maximum absorption rate at each wavelength. The minimum difference was 10%. On the other hand, as shown in FIG. 8, the transparent substrate with a film of Comparative Example 2 has an average absorption rate of 12% in the visible light wavelength range (400 nm to 700 nm), which is the maximum absorption rate at each wavelength. The minimum difference was 17%. It is considered that this is because a part of the metal layer made of tin was oxidized.

1 ... Transparent substrate 1a ... First main surface 1b ... Second main surface 2 ... Metal layer 3 ... Protective layer 4 ... Dielectric layer 5 ... Protective metal layer 10 ... Transparent substrate with film

Claims (8)

A metal layer forming process for forming a metal layer on a transparent substrate,
A protective metal layer forming step of forming a protective metal layer in contact with the metal layer on the opposite side of the metal layer from the transparent substrate.
A dielectric layer forming step of forming a dielectric layer in contact with the protective metal layer is provided on the side of the protective metal layer opposite to the transparent substrate by a sputtering method.
A method for manufacturing a transparent substrate with a film. The method for producing a transparent substrate with a film according to claim 1, wherein the protective metal layer has a thickness of 2 to 15 nm. The method for producing a transparent substrate with a film according to claim 1 or 2, wherein the protective metal layer is made of silicon or aluminum. The method for producing a transparent substrate with a film according to any one of claims 1 to 3, wherein the sputtering method is a reactive sputtering method. The film according to any one of claims 1 to 4, wherein in the dielectric layer forming step, the protective metal layer is reacted to form a protective layer composed of any of a metal oxide, a metal nitride and a metal oxynitride. Manufacturing method of transparent substrate with. The method for producing a transparent substrate with a film according to claim 1, wherein the metal layer is made of silver. The method for producing a transparent substrate with a film according to claim 1, wherein the metal layer is made of tin. Prior to the metal layer forming step, a protective oxide layer composed of silicon oxide or aluminum oxide is formed on the transparent substrate, and in the metal layer forming step, the metal layer is brought into contact with the protective oxide layer. The method for producing a transparent substrate with a film according to claim 7, which is formed.

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