JP2006206424A - Ag FILM FORMING METHOD AND LOW-EMISSIVITY GLASS - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a low-emissivity glass which has high visible light transmissivity and high heat-shielding property. <P>SOLUTION: An Ag film is formed by a magnetron sputtering method wherein the discharge voltage is kept at 200-350V and the magnetic field intensity on an Ag-target surface is kept at 700-1,200 oersted during Ag-film formation. In the low-emissivity glass, an oxide film and the Ag film, formed by the film forming method, are alternately stacked to form 2n (n≥1) layers in total on a glass substrate, and an oxide film is further stacked on the Ag film of the uppermost layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an Ag film used for low emission glass, and more particularly to a method for forming an Ag film and low emission glass.

  Low emission glass is known in which 2n + 1 (n ≧ 1) layers of a dielectric film and an Ag film are repeatedly laminated on a glass plate, and the uppermost layer is a dielectric film. As the dielectric film, a metal transparent oxide film is used (Patent Document 1).

  The low emission glass has a high shielding property due to the excellent infrared reflection effect exhibited by the Ag film while preventing the reflection of visible light by the dielectric film laminated before and after the Ag film and ensuring high visible light transmittance. It is well known as a glass with a transparent laminated film that exhibits heat.

  Such low emission glass is often used in a double glazing structure in which an air insulating layer is provided on a window glass of a building in order to sufficiently exhibit heat insulating properties.

  Since this low radiation glass is used for a window, it is usually formed by a sputtering method having a large area and excellent mass productivity. In particular, the magnetron sputtering method is used in which a magnet is disposed behind the target, a plasma is confined in the vicinity of the target surface by a generated magnetic field, and a film is formed by particles sputtered from the target.

A low radiation glass using an Ag film is required to have high heat shielding properties and high permeability. The high infrared reflectance of the Ag film is necessary for the expression of heat shielding properties, and the smaller the resistance of the Ag film, the higher the infrared reflectance. Although the resistance of the Ag film can be lowered by increasing the thickness of the Ag film, the transmittance of the Ag film decreases as the thickness increases, so the low emissivity glass is a balance between the transmittance of the Ag film and the emissivity. The thickness of the Ag film is determined.
JP 2002-173343 A

  In order to produce a low radiation glass having a particularly high heat shielding property while having a high visible light transmission property, the present invention provides an Ag film having a resistance lower than that of a prior art Ag film without increasing the thickness of the Ag film. The object is to produce a low-radiation glass having high heat shielding properties while having the same visible light transmittance as compared with the prior art.

  The method for forming an Ag film according to the present invention is the same as the method for forming an Ag film used for low emission glass. The Ag film is formed by a magnetron sputtering method while the discharge voltage during film formation is maintained at 200 to 350 V. This is a method for forming an Ag film.

  In the Ag film forming method of the present invention, the strength of the magnetic field on the Ag target surface is maintained at 700 to 1200 Oersted when the Ag film is formed. It is the manufacturing method of the Ag film | membrane characterized.

  In the low emission glass of the present invention, the oxide film and the Ag film formed by the film formation method of the Ag film alternately form 2n (n ≧ 1) layers on the glass substrate, and the uppermost Ag film is formed. The low emission glass (1) is characterized in that an oxide film is laminated thereon.

The low emission glass of the present invention is the low emission glass of (1), wherein n = 1, the thickness t1 of the second layer Ag film is in the range of 5 to 30 nm, and the ratio of the laminated films A low emission glass characterized by having a resistance of (35.8 / t1 + 2.3) × 10 ⁻⁶ Ωcm or less.

  The low emission glass of the present invention is the low emission glass, wherein the first layer oxide film is a zinc oxide film having a thickness of 20 to 60 nm and the third layer oxide film is 20 to 60 nm thick. It is a low emission glass comprising a zinc oxide film in the range of 60 nm and having a visible light transmittance of 70% or more.

The low emission glass of the present invention is the low emission glass of (1), where n = 2, the total thickness t2 of the Ag film is in the range of 15 to 35 nm, and the specific resistance of the laminated film is ( 168.6 / t2 + 1.3) × 10 ⁻⁶ Ωcm or less.

  In the low emission glass of the present invention, the first layer oxide film is a zinc oxide film having a thickness of 20 to 60 nm, and the second layer Ag film has a thickness of 7. The third layer oxide film is a zinc oxide film having a thickness of 40 to 120 nm, and the fourth layer Ag film is in a range of 7.5 to 17.5 nm. The low emission glass according to claim 6, wherein the oxide film of the fifth layer is a zinc oxide film having a thickness of 20 to 60 nm and has a visible light transmittance of 70% or more. is there.

  The method for forming an Ag film of the present invention provides an Ag film and a low radiation glass that are excellent in high visible light transmittance and heat shielding properties.

  The method for forming an Ag film according to the present invention can produce a highly transparent and low-resistance Ag film, and is preferably used as an Ag film for low-emission glass for the purpose of heat shielding a building window.

  For example, as shown in FIG. 1, the low emission glass has a film structure in which an Ag film 12 and a transparent oxide film 11 are alternately laminated on a glass substrate 3 to form a 2n layer, and a transparent oxide is the uppermost layer. The film 11 is formed.

  A float plate glass can be suitably used for the glass substrate. In addition, the film-forming of Ag film | membrane by this invention can also be used for a transparent resin board, without being limited to plate glass.

  The transparent oxide film 11 immediately above the glass substrate 3 is used to increase the adhesion and adhesion between the glass substrate and the Ag film, or between the films, thereby increasing the strength and durability of the laminated film of low radiation glass. Furthermore, it is used to increase the transmittance of the low emission glass.

  In the case of n = 1 (Ag film is one layer), the thickness of the Ag film 12 is preferably in the range of 5 to 30 nm. When the thickness is less than 5 nm, the resistance value is large and an effective heat shielding performance cannot be obtained. When the thickness exceeds 30 nm, the transparency is impaired and it is not preferable for use in a building window.

In the case of n = 2 (two Ag films), the total thickness of the Ag film 12 is preferably in the range of 15 to 35 nm. When the thickness of one layer of Ag film is less than 15 nm, the resistance value is large and an effective heat shielding performance cannot be obtained, and when the total thickness exceeds 35 nm, transparency is impaired and it is used for a window of a building. Is not preferred.
The specific resistance of the Ag film is a film having a small specific resistance even when the film thickness is the same as that of the comparative example (prior art), as is clear from FIG. 4 comparing the example and the comparative example.

Using the specific resistance value between the example and the comparative example, an approximate curve of the specific resistance with respect to the film thickness of the Ag film is obtained. When n = 1, the specific resistance with respect to the film thickness t1 of the Ag film. The value of (35.8 / t1 + 2.3) × 10 ⁻⁶ Ωcm is obtained. When n = 2, the thickness of the Ag film is t2 (168.6 / t2 + 1.3) × 10 ^−6. Ωcm.

Therefore, the specific resistance of the low radiation glass of the present invention is (35.8 / t1 + 2.3) × 10 ⁻⁶ Ωcm or less when n = 1, and when n = 2, (168.6) /T2+1.3)×10 ⁻⁶ Ωcm or less is obtained.

  The transparent oxide film 11 is formed by selecting at least one kind of oxides such as Si, Sn, Zn, Al, and Ti, and the selection depends on the optical film thickness and absorption of the oxide film. In addition to the characteristics, it is desirable to take into consideration the mechanical strength of the film itself and the adhesion to the adjacent layer.

  In particular, in order to obtain suitable film strength and durability of low emission glass and high transmittance, zinc oxide is suitable as the transparent oxide film, and the lowermost transparent oxide formed directly on the glass substrate 3 The thickness of the film 11 and the thickness of the uppermost transparent oxide film 11 are preferably 20 nm to 60 nm, and the thickness of the other transparent oxide film 11 is preferably 40 to 120 nm.

  Furthermore, the thickness of the lowermost transparent oxide film 11 formed directly on the glass substrate 3 and the uppermost transparent oxide film 11 of the low emission glass should be the same in order to increase the transparency. Is preferred.

  Furthermore, the lower limit 20 nm of the thickness of the transparent oxide film is a thickness necessary for maintaining the adhesion with the adjacent layer. In addition, the upper limit of the thickness of the transparent oxide film (60 nm for the lowermost transparent oxide film and the uppermost transparent oxide film formed directly on the glass substrate, other transparent oxides) If it exceeds 120 nm in the case of a physical film, a preferable transmittance in the visible range cannot be obtained.

  Instead of the transparent oxide film 11, a nitride film such as Si, Sn, Zn, Al, Ti, or a nitride oxide film may be used.

  Furthermore, in order to prevent oxidation of the Ag film, it is desirable to form a protective metal layer between the Ag film and the transparent oxide film.

  As the zinc metal used for the protective metal layer, Zn, Sn, Ti, Al, NiCr, Cr, Zn, Sn alloy (each metal containing Al or Sb metal in an amount of 0.0 to 10.0% by weight) or the like is used. be able to.

Further, it is preferable to use a zinc alloy (ZnAlO _x ) (hereinafter referred to as an AZO film) containing 2 to 12 atomic% of Al instead of the protective metal layer.

    The Ag film 12 and the transparent oxide film 11 are preferably formed by a sputtering method, and particularly preferably formed by using a magnetron sputtering apparatus as shown in FIG.

In the film forming apparatus shown in FIG. 2, an Ag target is used as the target 1, the glass substrate 3 is held by the substrate holder 2, the inside of the vacuum chamber 8 is evacuated using the vacuum pump 5, and the inside of the vacuum chamber 8 is further evacuated. Ar gas is introduced from the gas introduction pipe 7 by being controlled by a mass flow controller (not shown) to form an Ag film.
It is preferable that the pressure in the vacuum chamber 8 is adjusted by the vacuum pump 5 and the opening / closing valve 6 and the film is formed at 1 Pa or less.

  The discharge voltage when forming the Ag film 12 is preferably set to 350 V or less. When the discharge voltage exceeds 350V, a low resistance Ag film cannot be obtained. When the discharge voltage is less than 200V, the discharge becomes unstable and stable film formation becomes difficult.

  The discharge voltage is controlled by the voltage applied to the target using the DC power source 10 and is a potential difference with respect to the grounded substrate.

  In addition, when the Ag film 12 is formed, the magnetic field on the surface of the Ag target 1 is desirably 700 to 1200 Oersted. When the magnetic field on the surface of the Ag target 1 is less than 700 Oersted, there is a problem that the discharge voltage increases and the surface resistance of Ag increases. On the other hand, even if it exceeds 1200 Oersted, it is difficult to make the discharge voltage lower than 350V. Thus, an Ag film with low resistance cannot be obtained.

  The magnetic field on the surface of the Ag target 1 can be controlled by adjusting the magnetic field of the cathode magnet 4. The magnetic field of the cathode magnet 4 can be changed by exchanging permanent magnets having different magnetic forces, or by winding a coil around the permanent magnets to pass a direct current.

  The transparent oxide film 11 is formed by using a metal target for the target 1 and introducing oxygen gas from a gas introduction pipe, or by using the same oxide target as the oxide to be formed for the target 1. A film can be formed.

  For example, when forming a ZnO film, it is possible to form the film by using a Zn target as the target 1 and introducing Ar gas and oxygen gas in an appropriate mixing ratio from the gas introduction pipe 7. Alternatively, a ZnO film may be formed by introducing only Ar gas from the gas introduction pipe 7 using a ZnO target as the target 1.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

Example 1
A low emission glass in which a transparent oxide film 11, an Ag film 12, and a transparent oxide film 11 were laminated in this order on a glass substrate 3 as shown in FIG.

  The Ag film and the transparent oxide film were formed using a DC magnetron sputtering apparatus shown in FIG.

  A ZnO film was formed as the transparent oxide film 11. A Zn target was used as the target 1 and the glass substrate 3 was held by the substrate holder, and then the inside of the vacuum chamber 8 was evacuated using the vacuum pump 5.

  The atmospheric gas in the vacuum chamber 8 was adjusted by introducing Ar gas and oxygen gas from the gas introduction pipe 7 and controlling each of Ar gas and oxygen gas by a mass flow controller (not shown).

  A turbo molecular pump was used as the vacuum pump 5. The pressure in the vacuum chamber 8 during film formation was adjusted to 0.5 Pa or less by the opening / closing valve 6.

  The ZnO film increases the adhesion between the Ag film and the glass substrate, and was formed with a film thickness of 30 nm. The visible light transmittance of the low emission glass is increased by the ZnO film and the transparent oxide film formed on the upper layer.

  Next, after evacuating the inside of the vacuum chamber 8, Ar gas is controlled by a mass flow controller (not shown) from the gas introduction pipe 7 and introduced into the vacuum chamber 8, and the inside of the vacuum chamber 8 is made into an Ar gas atmosphere. An Ag film 12 was formed on the ZnO film 11 using an Ag target as the target 1.

  The Ag film 12 was formed in five thicknesses of 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, and 30 nm.

  During the formation of the Ag film 12, the pressure in the vacuum chamber was kept at 0.5 Pa or less by the vacuum pump 5 and the opening / closing valve 6. Further, the magnetic field of the cathode magnet 4 was adjusted by replacing a permanent magnet (not shown), and the strength of the magnetic field on the surface of the Ag target 1 was set to 700 Oersted. Furthermore, the input power of the DC power source was adjusted to set the discharge voltage to 320V.

  Next, an AZO (Al 2 wt% -containing ZnO) target was used on the Ag film 12 to form an AZO film having a thickness of 5 nm (not shown in FIG. 3).

  During the formation of the AZO film, the gas atmosphere and pressure in the pressure chamber 8 were the same as in the formation of the Ag film.

  Further, a ZnO film having a thickness of 30 nm was formed on the AZO film. The ZnO film was formed in the same manner as the ZnO film formed on the glass substrate 3.

Comparative Example 1
A low emission glass having the same film thickness was produced by adjusting the strength of the magnetic field on the surface of the Ag target 1 to 300 Oersted and the other conditions in the same manner as in the example. The discharge voltage at the time of forming the Ag film was 400V.

  The specific resistance of the low emission glass of Example 1 and Comparative Example 1 is a value as shown in FIG. 4 with respect to the thickness of the Ag film, and the low emission glass of Example 1 is compared with the low emission glass of Comparative Example 1. When compared with the film thickness of the same Ag film, Example 1 was a low radiation glass having a much smaller specific resistance than Comparative Example 1.

Further, regarding the Ag film of Example 1, the specific resistance of the Ag film was (37.3 / t1 + 2) × 10 ⁻⁶ Ωcm or less when the thickness t1 of the Ag film was in the range of 10 to 20 nm.

  Further, the spectral transmittance and the reflectance on the film surface side of the low emission glass using the Ag layer having a thickness of 10 nm prepared in Example 1 and Comparative Example 1 are as shown in FIGS. 5 and 6, respectively. While the transmittance of visible light is the same in both Example 2 and Comparative Example 2, the low emission glass of Example 2 has a higher reflectance in the infrared region than the low emission glass of Comparative Example 2, The heat shielding property was large.

Example 2
As shown in FIG. 7, two transparent oxide films 11 and an Ag film 12 are alternately formed on a glass substrate 3, and the transparent oxide film 11 is formed on the uppermost film. Was made.
The Ag film and the transparent oxide film were formed using a DC magnetron sputtering apparatus shown in FIG. When the Ag film 12 was produced, the strength of the magnetic field on the surface of the Ag target 1 was adjusted to 700 Oersted, and other conditions were the same as in Example 1.

  The thickness of the transparent oxide film 11 formed on the glass substrate 3 and the thickness of the uppermost transparent oxide film 11 are both 30 nm, and the thickness of the transparent oxide film 11 between the two Ag films is 60 nm. did. All the transparent oxide films were made of ZnO and were formed in the same manner as in Example 1.

Further, before forming a transparent oxide film on the Ag film, an AZO film (not shown in FIG. 7) was formed on the Ag film in the same manner as in Example 1.
The two layers of Ag film 12 had the same thickness, and a low emission glass having a total thickness of 20 nm and 30 nm was produced. At this time, the discharge voltage during the production of the Ag film was 320V.

Comparative Example 2
The intensity of the magnetic field on the surface of the Ag target 1 was adjusted to 300 Oersted, and other conditions were the same as in Example 2 to produce a low emission glass having the same film thickness. The discharge voltage at the time of preparation of the Ag film was 400V.

The specific resistance of the low emission glass of Example 2 and Comparative Example 2 is a value as shown in FIG. 4 with respect to the thickness of the Ag film. In Example 2, the specific film thickness is the same as that of Comparative Example 2 and is a comparative example. A low-radiation glass with lower resistance was obtained. In the low emission glass of Example 2, the total thickness t2 of the Ag film is in the range of 20 to 30 nm, and the specific resistance of the laminated film is (37.3 / (t2-12) +2) × 10 ⁻⁶ Ωcm or less. there were.

  With respect to the low emission glass having a total thickness of 20 nm of the Ag film of Example 2 and Comparative Example 2, measurement results of the spectral transmittance shown in FIG. 8 and the reflectance shown in FIG. 9 were obtained.

  The visible light transmittance shown in FIG. 8 is larger in the example, and the infrared reflection shown in FIG. 9 is also larger in the example.

  Therefore, the embodiment using the method for forming an Ag film according to the present invention is a low radiation glass having a better visible light transmittance and better heat shielding performance than the conventional technique with the same Ag film thickness. It was.

  The production method of the Ag film of the present invention is not limited to a glass substrate, but can be applied to a transparent resin plate or resin film. It is possible to provide a radiation plate, a low radiation film, and a transparent electromagnetic shielding plate and electromagnetic shielding film.

It is sectional drawing which shows the film | membrane structure of low radiation glass. It is the schematic of a film-forming apparatus. It is sectional drawing which shows the film | membrane structure of the low radiation glass of Example 1 and Comparative Example 1. It is a graph which shows the film thickness of Ag film | membrane, and the relationship of specific resistance. It is a graph which shows the transmittance | permeability. It is a graph which shows a reflectance. It is sectional drawing which shows the film | membrane structure of the low radiation glass of Example 2 and Comparative Example 2. It is a graph which shows the transmittance | permeability. It is a graph which shows a reflectance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Target 2 Substrate holder 3 Glass substrate 4 Cathode magnet 5 Vacuum pump 6 On-off valve 7 Gas introduction tube 8 Vacuum chamber 9 Power cord 10 DC power source 11 Oxide film 12 Ag film

Claims (7)

  In a film formation method for an Ag film used for low emission glass, the Ag film is formed by magnetron sputtering while maintaining a discharge voltage of 200 to 350 V during film formation. .   2. The method of forming an Ag film according to claim 1, wherein the strength of the magnetic field on the surface of the Ag target is maintained at 700 to 1200 oersted when the Ag film is formed.   A low emission glass in which an oxide film and an Ag film are alternately formed on a glass substrate to form 2n (n ≧ 1) layers, and an oxide film is laminated on the uppermost Ag film. A low emission glass characterized in that the film is an Ag film of the film forming method according to claim 1 or 2. 4. The low emission glass according to claim 3, wherein n = 1, the thickness t1 of the second layer Ag film is in the range of 5 to 30 nm, and the specific resistance of the laminated film is (35.8 / t1 + 2). .3) × 10 ⁻⁶ Ωcm or less, the low release glass according to claim 3.   The first layer oxide film is a zinc oxide film having a thickness of 20 to 60 nm, the third layer oxide film is a zinc oxide film having a thickness of 20 to 60 nm, and has a visible light transmittance of 70. The low emission glass according to claim 4, wherein the low emission glass is at least%. The low emission glass according to claim 3, wherein n = 2, the total thickness t2 of the Ag film is in the range of 15 to 35 nm, and the specific resistance of the laminated film is (168.6 / t2 + 1.3). The low emission glass according to claim 3, wherein the low emission glass is × 10 ⁻⁶ Ωcm or less.   The thickness of the oxide film of the first layer is a zinc oxide film in the range of 20 to 60 nm, the thickness of the Ag film of the second layer is in the range of 7.5 to 17.5 nm, and the oxide of the third layer The film is a zinc oxide film having a thickness of 40 to 120 nm, the thickness of the fourth Ag film is in the range of 7.5 to 17.5 nm, and the oxide film of the fifth layer is 20 to 60 nm. The low-emission glass according to claim 6, wherein the low-emission glass is a zinc oxide film in the range of 1 to 5 and has a visible light transmittance of 70% or more.

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