JP2019035100A - Method for manufacturing reflective film - Google Patents

Abstract

To improve both reflectance and gas corrosion resistance.SOLUTION: A method for manufacturing a reflective film including at least a reflective layer includes a reflective layer formation step S2 of vapor-depositing AgBi as a raw material having a Bi composition ratio of 0.01-0.8%.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a reflective film, and more particularly to a technique suitable for improving both reflectance and gas corrosion resistance.

The development of light reflecting films using Ag has been widely performed.
In Patent Document 1, Bi and / or Sb is contained in Ag to suppress a decrease in reflectance over time (paragraphs 0018 to 0022).
In Patent Document 2, an oxide film of a predetermined metal such as Zr is formed as a second layer on an Ag film to improve sulfidation resistance and heat resistance and to suppress a decrease in reflectance (paragraph 0020). ~ 0024).

However, in both Patent Document 1 (paragraphs 0031 to 0038) and Patent Document 2 (paragraphs 0062 to 0065), the reflective film is manufactured using the sputtering method.
When manufacturing a reflective film using a sputtering method, for example, as shown in FIG. 9, when manufacturing a polyhedral reflector 50 such as a polygon mirror, simultaneously forming a reflective film on a plurality of film formation surfaces 52 Therefore, it is necessary to reduce the distance from the target 60 to the film formation surface 52, and unevenness in film thickness occurs between the film formation surfaces 52. In order to avoid this, it is necessary to perform film formation while switching the film formation surfaces 52 one by one, and the productivity is not good.

Patent Document 3 discloses a method for manufacturing a reflective film using a vapor deposition method (paragraph 0058).
In the technique of Patent Document 3, since the film is formed by the vapor deposition method instead of the sputtering method, the distance from the vapor deposition source to the film formation surface is separated even when a polyhedral reflector such as a polygon mirror is manufactured. It is considered that the occurrence of film thickness unevenness can be suppressed, and since it is not necessary to switch the film formation surface, productivity can be improved and the above problem can be solved.

In particular, Patent Document 3 attempts to obtain a corrosion resistance and high spectral reflectance by forming a reflective film 52 of a Bi-containing silver alloy by vapor deposition (paragraphs 0028 and 0058).
In Production Example 1 according to the example of Patent Document 3, an adhesion improving film 51 (Cr film and Cu film) / reflection film 52 (Ag-Bi film) / intermediate film 54 (Al ₂ O ₃ film) is formed on a substrate. ) / Reflection increasing film 53 (ZrO ₂ film, SiO ₂ film, ZrO ₂ film and SiO ₂ film) / Light reflecting mirror on which a water repellent film is formed is manufactured. Is forming. In the formation of the reflective film 52, an Ag—Bi alloy is used as a raw material evaporation material (paragraphs 0071, 0073, and 0078).

JP 2004-126497 A JP 2011-170326 A JP 2010-204380 A

However, in the formation of the reflective film 52 in Production Examples 1 and 2 of Patent Document 3, the composition ratio of Bi is 1 atomic% in the raw material Ag—Bi alloy (paragraph 0071), and the composition ratio of Bi is large. Although corrosion resistance can be improved, the reflectance may decrease on the other hand, and there is still room for improvement in order to improve both reflectance and corrosion resistance. In addition, when the composition ratio of Bi taken into the film increases, Bi itself weakens the film quality and the adhesiveness decreases.
Accordingly, a main object of the present invention is to provide a method for manufacturing a reflective film using a vapor deposition method, and to provide a method for manufacturing a reflective film capable of improving both reflectivity and gas corrosion resistance. .

In order to solve the above problems, according to the present invention,
In a method for producing a reflective film including at least a reflective layer,
In the step of forming the reflective layer, a reflective film manufacturing method is provided, in which AgBi is vapor-deposited as a raw material, and the composition ratio of Bi of the raw material is 0.01 to 0.8 atomic%.

  According to the present invention, the composition ratio of Bi as a raw material is optimized, and it is possible to improve both reflectance and gas corrosion resistance.

It is a perspective view which shows schematic structure of a reflective mirror. It is sectional drawing which shows schematic structure of a reflecting film. It is a schematic flowchart which shows the manufacturing method of a reflecting film over time. It is a figure for demonstrating the formation method of a reflection layer. It is the schematic which shows the state which mounted the laser radar in the vehicle. It is a perspective view which shows schematic structure of the laser radar to which a reflective mirror is applied. It is a figure for demonstrating the relationship between an Ag-Bi layer and Cl suppression. It is a figure which shows the compositional analysis result of the depth direction of the reflecting film of the comparative example 3 and Example 3. FIG. It is a figure for demonstrating the problem of the conventional manufacturing method (sputtering).

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
About "-" which shows a numerical range, the numerical value described as an upper limit and a lower limit is also contained in the said numerical range.

[Reflector]
As shown in FIG. 1, the reflecting mirror 10 is a so-called polygon mirror that is a polyhedral reflecting mirror, and has a form in which two quadrangular pyramids are abutted. In the reflecting mirror 10, four trapezoidal reflecting surfaces 12 and 14 are arranged on the top and bottom, respectively, to form a total of eight reflecting surfaces 12 and 14. A reflective film 30 is formed on each of the reflective surfaces 12 and 14 (see FIG. 2).
As shown in FIG. 2, the reflecting mirror 10 includes a base material 20 and a reflective film 30 that is a thin film, and the reflective film 30 is formed on the surface of the base material 20 (respective reflecting surfaces 12 and 14).

The base material 20 is a member that becomes a base of the reflecting mirror 10, and has a flat optical surface 21 that is covered by the reflective film 30.
The substrate 20 is made of a resin material such as polycarbonate (PC), cycloolefin polymer (COP), acrylic resin (PMMA), polyethylene terephthalate (PET). The substrate 20 is not limited to these resin materials, and may be formed of quartz, glass, ceramics, or other inorganic materials.

The reflective film 30 includes an adhesion layer 31 formed as a base on the base material 20, a reflection layer 32 formed on the adhesion layer 31, and an increased reflection layer 33 formed on the reflection layer 32. . The reflection layer 32 is disposed between the adhesion layer 31 and the increased reflection layer 33.
Here, a description will be given of a mode in which the reflective film 30 has a three-layer structure of the adhesion layer 31, the reflective layer 32, and the increased reflective layer 33, but the reflective film 30 may be configured by only the reflective layer 32.

The adhesion layer 31 may be composed of one layer or may be composed of two or more layers.
Here, the term “two or more layers” means a layer of a material having good adhesion to the upper reflective layer 32 and a layer of a material having good adhesion to the lower substrate 20.
When the adhesion layer 31 has a single-layer configuration, it is necessary to select a material that has good adhesion to both the reflective layer 32 and the substrate 20. Furthermore, in order to improve the environmental resistance of the reflective layer 32, the influence of moisture from the substrate 20 must be taken into account. It is necessary to adjust the film stress of each film to achieve a balance between them in order to suppress film floating and cracks associated with stress on each film caused by high temperature and high humidity environment and high temperature dry environment. .

There are several media for blocking moisture in the adhesion layer 31, but one is preferably a layer mainly composed of aluminum oxide.
As the layer mainly composed of aluminum oxide, “Substance M2” or “Substance M3” manufactured by Merck Co., Ltd. in which La ₂ O ₃ is mixed with aluminum oxide in an amount of about 5 to 10% is used in addition to pure aluminum oxide. Including cases.
When the layer mainly composed of aluminum oxide used in the adhesion layer 31 is formed without performing ion assist, the moisture blocking effect is recognized, but the tensile stress of the material itself is strong, and durability in a high temperature and high humidity environment is improved. Not suitable for holding. Therefore, it is preferable to make the film dense by using an ion assist method to achieve both the moisture blocking effect and the stress adjusting effect.
As a result of various experiments, it was found that the resistance to high temperature and high humidity can be improved by adjusting the film formation conditions such as the ion assist output and the film formation rate in consideration of the correlation with the film stress of the entire layer. . That is, as the layer constituting the lower side of the adhesion layer 31, a layer mainly made of aluminum oxide formed using an ion assist method is preferable. The layer constituting the upper side of the adhesion layer 31 is preferably selected from at least one of LaTiO _3, CeO ₂ , Y ₂ O ₃ and SnO ₂ as a material having good adhesion with silver.

Specifically, the adhesion layer 31 may include a first layer 31a on the base material 20 side and a second layer 31b on the reflective layer 32 side.
Both layers 31a and 31b have a thickness of about 10 to 200 nm, more preferably 20 to 120 nm.
The first layer 31a is a thin film layer that has a role of a buffer layer that directly adheres to the base material 20 and allows some permeation while blocking moisture. The second layer 31b is a thin film layer that is in direct contact with the reflective layer 32 and has a role of reliably blocking moisture.
The first layer 31a on the substrate 20 side is a layer mainly made of aluminum oxide as described above, and is preferably formed using an ion assist method. The second layer 31b on the reflective layer 32 side is a layer of a material selected from at least one of LaTiO ₃ , CeO ₂ , Y ₂ O ₃ and SnO ₂ as described above, and is formed using an ion assist method. Preferably it is done.

In addition, although both layers 31a and 31b have an effect of improving the adhesion even if the film thickness is less than 10 nm as a whole, if the film thickness is less than 10 nm, the growth of the thin film is in progress, and sufficient moisture blocking is achieved due to the continuity of the film. In order to exert the effect, the film thickness is preferably 10 nm or more.
On the other hand, even when the film thickness exceeds 200 nm, there are sufficient adhesion and moisture blocking effects, but there are side effects such as increasing the surface roughness of the substrate 20 and increasing the influence of film stress as the thickness increases. From the viewpoint of the adhesion layer, the film thickness is preferably controlled to 200 nm or less.

The reflective layer 32 is a thin film formed of an alloy of Ag and Bi.
The reflective layer 32 is a layer formed by vapor deposition using AgBi as a raw material. In particular, the composition ratio of Bi as the raw material is 0.01 to 0.8 atomic%, preferably 0.02 to 0.5 atomic%. Is done.
The reflective layer 32 has a thickness of about several tens to 100 nm, more preferably about 50 to 100 nm.

The increased reflection layer 33 is a dielectric multilayer film in which high refractive index material layers 33a and low refractive index material layers 33b are alternately stacked, and the uppermost layer is preferably formed of the low refractive index material layer 33b.
The number of layers of the high refractive index material layer 33a and the low refractive index material layer 33b is appropriately set.
The high refractive index material layer 33a has a refractive index of 1.8 or more, and the low refractive index material layer 33b has a refractive index of 1.55 or less.
The material of the high refractive index material layer 33a is selected from at least one of TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , LaTiO ₃ , ZrO _2, and a mixed material of these materials.
The material of the low refractive index material layer 33b is selected from at least one of SiO ₂ and a mixed material obtained by mixing aluminum oxide with SiO ₂ .

The high-refractive index material layer 33a and the low-refractive index material layer 33b are set to have a film thickness corresponding to the refractive index for each layer depending on the optical design, and even the same low-refractive index material layer 33b may have different thicknesses.
Further, when the increased reflection layer 33 is composed of a plurality of high refractive index material layers 33a and a plurality of low refractive index material layers 33b, for example, the plurality of high refractive index material layers 33a are formed of different materials having different refractive indexes. can do.
Furthermore, the single low refractive index material layer 33b can be composed of a plurality of types of low refractive index material layers, and similarly, the single high refractive index material layer 33a is composed of a plurality of types of high refractive index material layers. You can also

Note that the first reflective layer 33 may be formed with a first layer 33 f that is in direct contact with the reflective layer 32. The first layer 33f is made of a material mainly containing aluminum oxide. In the multilayer film design for increasing the reflectance of the reflective layer 32, when the first layer 33f is interposed between the high refractive index material layer 33a and the reflective layer 32, the reflection performance can be improved.
Note that the first layer 33f has a refractive index of 1.55 or more and less than 1.80. The first layer 33f in contact with the reflective layer 32 can be regarded as a medium refractive index material layer in terms of a higher refractive index than the uppermost low refractive index material layer 33b, but in a broad sense, the high refractive index material layer 33a. Therefore, it is called a low refractive index material layer.

[Manufacturing method of reflection mirror (reflection film)]
Then, the manufacturing method of the reflective mirror 10 (mainly reflective film 30) is demonstrated.

As shown in FIG. 3, the manufacturing method of the reflecting mirror 10 is mainly
(I) Step S1 of preparing the substrate 20;
(Ii) Step S2 of forming the adhesion layer 31,
(Iii) Step S3 of forming the reflective layer 32;
(Iv) Step S4 of forming the increased reflection layer 33;
It has.

  In the preparation step S1 of the base material 20, a base member formed of a resin material such as polycarbonate (PC) is prepared.

  From the formation step S2 of the adhesion layer 31 to the formation step S4 of the enhanced reflection layer 33, a single ion beam assisted vapor deposition apparatus (deposition apparatus using a known ion assist method) is used while switching the presence or absence of an ion beam. Each layer is preferably formed.

In the formation step S2 of the adhesion layer 31, a material mainly composed of aluminum oxide is vapor-deposited on the base material 20 by using an ion assist method to form the first layer 31a.
Thereafter, a material selected from at least one of LaTiO ₃ , CeO ₂ , Y ₂ O ₃ and SnO ₂ is vapor-deposited on the first layer 31a by using an ion assist method to form the second layer 31b.
In the formation step S2 of the adhesion layer 31, the denseness or density of the first layer 31a and the second layer 31b can be adjusted by adjusting the degree of ion beam irradiation.

In the formation process S3 of the reflective layer 32, the reflective layer 32 is formed using a normal vapor deposition method.
Here, as shown in FIG. 4, AgBi having a Bi composition ratio of 0.01 to 0.8 atomic% is used as a raw material to fill the vapor deposition source 40, and the vapor deposition source 40 is heated to form an Ag-Bi alloy base. A reflective film 32 is formed by vapor deposition on the material 20 (second layer 31b of the adhesion layer 31).
The composition ratio of Bi of the raw material is preferably 0.02 to 0.5 atomic%.

In particular, in the formation step S3 of the reflective layer 32, it is preferable to preheat the vapor deposition source 40 including the raw material, and then perform main heating at a temperature higher than the preheating for vapor deposition. Alternatively, in the reflective layer 32 forming step S3, an openable / closable shutter 42 is disposed between the vapor deposition source 40 and the substrate 20, and vapor deposition is performed with the shutter 42 closed, and then the shutter 42 is formed. Vapor deposition is recommended.
That is, the raw material Bi has a lower melting point than Ag and evaporates first. If Ag—Bi alloy is simply deposited as in Production Examples 1 and 2 of Patent Document 3, a large amount of Bi evaporates first, and a large amount of Bi is mixed into the reflective film 32, which may lower the reflectance. There is sex.
In this respect, if the vapor deposition source 40 is preheated, it is possible to suppress a large amount of Bi in the raw material from being vaporized first. Even in a two-stage process including opening and closing of the shutter 42, Bi in the raw material can be shielded by the shutter 42 first, and then Ag and Bi can be evaporated simultaneously. As a result, it is possible to form the reflective layer 32 in which Ag and Bi are balanced, and it is possible to suppress a decrease in reflectance.
In the case of preheating the vapor deposition source 40, the heating temperature of the main heating is set higher than the heating temperature of the preheating in order to increase the film formation rate. If the film formation rate is increased, the kinetic energy increases and the strength of the reflective film 32 can be improved.

Note that, as described above, the reflective film 30 may be configured by only the reflective layer 32.
In such a case, when the base material 20 is prepared in the preparation step S <b> 1 of the base material 20, the reflective layer 32 may be directly formed on the base material 20 and may be used as the reflective mirror 10.

In the formation step S4 of the increased reflection layer 33, a material mainly composed of aluminum oxide is vapor-deposited on the reflection layer 32 by using an ordinary vapor deposition method to form the first layer 33f.
Thereafter, a material selected from at least one of TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , LaTiO ₃ , ZrO _2, and a mixed material of these materials is formed on the first layer 33 f using an ion assist method. To form a high refractive index material layer 33a.
Thereafter, a material selected from at least one of a mixed material obtained by mixing aluminum oxide with SiO ₂ and SiO ₂ is vapor-deposited on the high refractive index material layer 33a using a normal vapor deposition method, and the low refractive index material layer 33b is formed.
Through the above processing, the reflecting mirror 10 can be manufactured.

[Application of reflector]
The reflecting mirror 10 can be applied to, for example, a vehicle laser radar.
That is, as shown in FIG. 5, the laser radar LR is provided behind the front window 1a of the vehicle 1 or behind the front grille 1b.
As shown in FIG. 6, the laser radar LR is mainly composed of a light projecting system LPS, a reflecting mirror 10, and a light receiving system RPS.
The light projecting system LPS includes a pulsed semiconductor laser LD that emits a laser beam, and a collimator lens CL that converts divergent light from the semiconductor laser LD into parallel light. According to the light projecting system LPS, the laser light collimated by the collimator lens CL is reflected by the reflecting surfaces 12 and 14 of the reflecting mirror 10 and scanned and projected toward the object OBJ side (see FIG. 5). Can do. On the other hand, the light receiving system RPS includes a lens LS that collects reflected light reflected by the object OBJ and reflected by the reflecting surfaces 14 and 12 of the reflecting mirror 10, and a photodiode PD that receives the light collected by the lens LS. And has.
The reflecting mirror 10 is held so as to be rotatable around a rotation axis RO that is an axis.

  Next, the distance measuring operation of the laser radar LR will be described.

The divergent light intermittently emitted from the semiconductor laser LD in a pulsed manner is converted into a parallel light beam by the collimating lens CL, enters the point P1 of the reflecting surface 12 of the rotating reflecting mirror 10, is reflected here, and is reflected by the reflecting surface. 14 is further reflected at a point P2 on the reflecting surface 14 and is projected to the object OBJ side.
Thereafter, the laser beam reflected by the object OBJ out of the projected light beam is incident again on the point P3 of the reflecting surface 14 of the reflecting mirror 10, is reflected here, travels along the rotation axis RO, and further The light is reflected at the point P4 on the reflection surface 12, collected by the lens LS, and detected by the light receiving surface of the photodiode PD.
The object OBJ can be detected by the distance measuring operation described above.

(1) Production of sample A reflective film was formed on the substrate as follows using GENER-1300 manufactured by OPTRAN as a vapor deposition apparatus. As the substrate, polycarbonate (PC) H-3000R manufactured by Mitsubishi Engineering Plastics Co., Ltd., which was molded to a thickness of 3 mm with a diameter of 30 mm was used. Since the film formation surface (reflecting surface) of the actual product is located at a deposition incident angle of 45 degrees, the substrate is tilted by 45 degrees with respect to the surface orthogonal to the deposition source or the support surface of the deposition holder. Installed in.
In Comparative Examples 1 to 3 and Examples 1 to 8, the reflective film was composed only of the reflective layer.
In Examples 10 to 12, the reflective film was composed of an adhesion layer, a reflective layer, and an increased reflective layer.
The structure of each layer is shown in Table 2 and Table 3.

(1.1) Comparative Example 1
Ag was loaded into a molybdenum resistance heating boat.
After depressurizing the vacuum tank to 1 × 10 ⁻⁴ Pa, energize and heat the molybdenum resistance heating boat (preliminary heating), and then perform main heating at a temperature higher than the preheating while appropriately adjusting the energization heating conditions of the resistance heating boat. Then, vapor deposition was performed at a formation rate of 16.0 nm / second to form an Ag layer (reflection layer) having a layer thickness of 80 nm.
As preheating (conditions), the temperature was raised to 200 A in 10 seconds and held for 10 seconds, raised to 270 A in 10 seconds, held for 5 seconds, raised to 290 A in 5 seconds, and held for 85 seconds.

(1.2) Comparative Examples 2 and 3
Kobelco KGB5 (Ag-0.005Bi) was loaded into a resistance heating boat made of molybdenum. Otherwise, in the same manner as in Comparative Example 1, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.005 atomic% was formed, and this was designated as Comparative Example 2.
Kobelco KGB1000 (Ag-Bi) was loaded into a resistance heating boat made of molybdenum. Otherwise, in the same manner as in Comparative Example 1, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 1 atomic% was formed, and this was designated as Comparative Example 3.

(1.3) Examples 1 and 2
KOBELCO KGB10 (Ag-0.01Bi) was loaded into a resistance heating boat made of molybdenum. Otherwise, in the same manner as in Comparative Example 1, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.01 atomic% was formed, and this was used as Example 1.
Kobelco KGB800 (Ag-0.8Bi) was loaded into a resistance heating boat made of molybdenum. Otherwise, in the same manner as in Comparative Example 1, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.8 atomic% was formed, and this was used as Example 2.

(1.4) Examples 3 and 4
Kobelco KGB20 (Ag-0.02Bi) was loaded into a resistance heating boat made of molybdenum. Otherwise, in the same manner as in Comparative Example 1, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.02 atomic% was formed, and this was designated as Example 3.
Kobelco KGB500 (Ag-0.5Bi) was loaded into a resistance heating boat made of molybdenum. Otherwise, in the same manner as in Comparative Example 1, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.5 atomic% was formed, and this was designated as Example 4.

(1.5) Examples 5 and 6
In Example 3, no preheating was performed. Otherwise, in the same manner as in Example 3, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.02 atomic% was formed.
In Example 4, no preheating was performed. Otherwise, in the same manner as in Example 4, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.5 atomic% was formed.

(1.6) Examples 7 and 8
In Example 3, the heating time (holding time) of preheating was doubled. Otherwise, in the same manner as in Example 3, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.02 atomic% was formed.
In Example 4, the heating time (holding time) of preheating was doubled. Otherwise, in the same manner as in Example 4, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.5 atomic% was formed.

(1.7) Example 10
Merck Al ₂ O ₃ was loaded into a copper crucible.
The vacuum chamber was depressurized to 1 × 10 ⁻⁴ Pa, and then heated with an electron gun, and the electric heating condition of the electron gun was appropriately adjusted and deposited at a formation rate of 5.0 nm / second. Al ₂ O with a layer thickness of 60 nm _Three layers (the first layer of the adhesion layer) were formed. During vapor deposition, O ₂ was introduced until 1.5 × 10 ⁻² Pa was reached.
Mercury LaTiO ₃ (Substance H4) was loaded into a copper crucible.
The vacuum chamber was depressurized to 1 × 10 ⁻⁴ Pa, then heated with an electron gun, and the current heating conditions of the electron gun were adjusted as appropriate to deposit at a formation rate of 4.0 nm / second, and a LaTiO ₃ layer having a layer thickness of 60 nm (Second layer of the adhesion layer) was formed.
In the formation of the adhesion layer, IAD (Ion Assisted Deposition) was used. The IAD conditions were as shown in Table 1.

  In Table 1, “Voltage [V]” means the beam voltage of the ion gun, and “Current [A]” means the beam current of the ion gun. “ACC [V]” means acceleration voltage. “E / B [%]” means the power ratio between Emission and Beam. Emission is the power of the neutralizer that neutralizes ions, and Beam is the power of ion assist. “Gas1, O2 [SCCM]”, “Gas2, Ar [SCCM]” and “Gas3, Ar [SCCM]” indicate the supply flow rates of oxygen and argon. “Gas2, Ar [SCCM]” indicates the supply amount of the argon gas component to the ion gun, and “Gas3, Ar [SCCM]” indicates the supply amount of the argon gas to the neutralizing gun.

Kobelco KGB250 (Ag-0.25Bi) was loaded into a molybdenum resistance heating boat.
After depressurizing the vacuum tank to 1 × 10 ⁻⁴ Pa, energize and heat the molybdenum resistance heating boat (preliminary heating), and then perform main heating at a temperature higher than the preheating while appropriately adjusting the energization heating conditions of the resistance heating boat. Thus, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.25 atomic% was formed at a deposition rate of 16.0 nm / second.
As preheating (conditions), the temperature was raised to 200 A in 10 seconds and held for 10 seconds, raised to 270 A in 10 seconds, held for 5 seconds, raised to 290 A in 5 seconds, and held for 85 seconds.

In the same manner as the first layer of the adhesion layer, an Al ₂ O ₃ layer having a thickness of 25 nm (first layer of the reflective layer) was formed (here, IAD was not used).
In the same manner as the second layer of the adhesion layer, a LaTiO ₃ layer having a layer thickness of 75 nm (second layer of the increased reflection layer) was formed.
Merck SiO ₂ was loaded into a copper crucible.
The vacuum chamber was depressurized to 1 × 10 ⁻⁴ Pa, then heated with an electron gun, and the electric heating condition of the electron gun was adjusted as appropriate to deposit at a formation rate of 8.0 nm / second, and a SiO ₂ layer having a layer thickness of 15 nm (The third layer of the increased reflection layer) was formed.
Similarly to the second layer of the adhesion layer and the second layer of the increased reflection layer, a LaTiO ₃ layer (fourth layer of the increased reflection layer) having a layer thickness of 75 nm was formed.
A SiO ₂ layer having a thickness of 30 nm (fifth layer of the increased reflection layer) was formed in the same manner as the third layer of the increased reflection layer.

(1.8) Example 11
ZnS was loaded into a molybdenum resistance heating boat.
After depressurizing the vacuum chamber to 1 × 10 ⁻⁴ Pa, the resistance heating boat was energized and heated, the current heating conditions of the resistance heating boat were adjusted as appropriate, and vapor deposition was performed at a formation rate of 4.0 nm / sec. A layer (adhesion layer) was formed.

Kobelco KGB250 (Ag-0.25Bi) was loaded into a molybdenum resistance heating boat.
After depressurizing the vacuum tank to 1 × 10 ⁻⁴ Pa, energize and heat the molybdenum resistance heating boat (preliminary heating), and then perform main heating at a temperature higher than the preheating while appropriately adjusting the energization heating conditions of the resistance heating boat. Thus, an Ag—Bi layer (reflective layer) having a layer thickness of 80 nm and a Bi composition ratio of 0.25 atomic% was formed at a deposition rate of 16.0 nm / second.
As preheating (conditions), the temperature was raised to 200 A in 10 seconds and held for 10 seconds, raised to 270 A in 10 seconds, held for 5 seconds, raised to 290 A in 5 seconds, and held for 85 seconds.

Mercury LaTiO ₃ (Substance H4) was loaded into a copper crucible.
The vacuum chamber was depressurized to 1 × 10 ⁻⁴ Pa, then heated with an electron gun, and the current heating conditions of the electron gun were adjusted as appropriate to deposit at a formation rate of 4.0 nm / second, and a LaTiO ₃ layer with a layer thickness of 1 nm (First layer of an increased reflection layer) was formed. The vapor deposition used IAD (Ion Assisted Deposition). The IAD conditions were as shown in Table 1.

  A ZnS layer having a thickness of 40 nm (second layer of the enhanced reflection layer) was formed in the same manner as the adhesion layer.

(1.9) Example 12
TiO ₂ was loaded into a copper crucible.
The vacuum chamber was depressurized to 1 × 10 ⁻⁴ Pa, then heated with an electron gun, and the electric heating condition of the electron gun was appropriately adjusted and deposited at a formation rate of 5.0 nm / second, and a TiO ₂ layer having a layer thickness of 20 nm (First layer of the adhesion layer) was formed. During vapor deposition, O ₂ was introduced until 1.5 × 10 ⁻² Pa was reached. The vapor deposition used IAD (Ion Assisted Deposition). The IAD conditions were as shown in Table 1.
ZnS was loaded into a molybdenum resistance heating boat.
After depressurizing the vacuum chamber to 1 × 10 ⁻⁴ Pa, the resistance heating boat was energized and heated, the current heating conditions of the resistance heating boat were adjusted as appropriate, and vapor deposition was performed at a formation rate of 4.0 nm / sec. A layer (second layer of the adhesion layer) was formed.

  Thereafter, a reflective layer similar to the reflective layer of Example 10 was formed.

Thereafter, a ZnS layer having a thickness of 40 nm (the first layer of the increased reflection layer) was formed in the same manner as the second layer of the adhesion layer.
In the same manner as the first layer of the adhesion layer, a 20 nm thick TiO ₂ layer ( _second layer of the increased reflection layer) was formed.
Thereafter, a SiO ₂ layer having a layer thickness of 78 nm, a LaTiO ₃ layer having a layer thickness of 110 nm, and a SiO ₂ layer having a layer thickness of 20 nm were formed in the same manner as in the third to fifth layers of the increased reflection layer of Example 10. .

(2) Evaluation of sample (2.1) Measurement of reflectance Using a spectrophotometer MCPD3000 manufactured by Otsuka Electronics Co., Ltd., P-polarized light reflected at 45 degrees was measured in a wavelength range of 870 nm ± 30 nm.
Tables 2 and 3 show the measurement results of the reflectance.
In Tables 2 and 3, the criteria for ◎, ○, and Δ are as follows.
◎; 97% or more ○; more than 95% and less than 97% △; 95%

(2.2) Evaluation of gas corrosion resistance As a gas corrosion test, the interior of the chamber is kept at 40 ° C. (± 1) and 80% RH (± 3) and filled with the following gas, and a sample is placed inside the chamber. Left for 21 days. This is because the atmosphere contains a large amount of the following gas and the metal system is deteriorated by the gas. The appearance after the gas corrosion test was visually observed to evaluate gas corrosion resistance.
Gas type and concentration: H ₂ S (0.01 ppm (± 0.005)), Cl ₂ (0.01 ppm (± 0.005)), NO ₂ (0.2 ppm (± 0.02)), SO ₂ (0.2 ppm (± 0.02))
The evaluation results are shown in Table 2 and Table 3.
In Tables 2 and 3, the criteria for ◎, ○, Δ, and × are as follows.
◎: No abnormality ○: About 1/4 film lift is observed Δ: About 1/2 film lift is observed X: Film lift is observed over the entire surface

(2.3) Evaluation of adhesiveness Nichiban cello tape (registered trademark) CT-18 was attached to the sample, and then the tape was pulled up vertically to confirm whether there was film peeling and to evaluate the adhesiveness.
The evaluation results are shown in Table 2 and Table 3.
In Tables 2 and 3, the criteria for ◎, ○, and X are as follows.
◎: No film peeling ○: Film peeling of about 3 mm is confirmed on the outer periphery of the film ×: Film peeling is confirmed over the entire surface

(3) Summary As shown in Table 2 and Table 3, from the comparison between Comparative Examples 1-3 and Examples 1-8, 10-12, good results were obtained in the latter Examples 1-8, 10-12. It was.
In order to improve both reflectance and gas corrosion resistance, it can be seen that it is useful to deposit AgBi as a raw material and to set the composition ratio of Bi to 0.01 to 0.8 atomic%. From comparison between Examples 1-2 and Examples 3-4 in particular, it can be seen that it is useful to set the composition ratio of Bi to 0.02-0.5 atomic%.
In Comparative Example 1, Cl gas reacted with Ag during the gas corrosion test and agglomerated and was inferior in gas corrosion resistance, whereas Comparative Examples 2-3 and Examples 1-8 had gas corrosion resistance. It has improved. This is because, as shown in FIG. 7, Bi precipitates on the surface layer of the Ag—Bi layer (reflective layer) to form a few Bi ₂ O ₃ films, thereby suppressing Cl formation.

When XPS measurement and Ar sputtering were repeated for Comparative Example 3 and Example 3, and composition analysis in the depth direction of the reflective film was performed, as shown in FIG. Therefore, it was considered that a reflective film in which Ag and Bi were balanced was formed.
For the horizontal axis in FIG. 8, the smaller the number of sputtering, the surface side of the reflective film is shown, and the more the number of sputtering, the substrate side.

From a comparison between Examples 3-4 and Examples 5-6, it can be seen that preheating is more useful in improving both reflectivity and gas corrosion resistance.
However, from a comparison between Examples 3-4 and Examples 7-8, in order to improve both reflectance and gas corrosion resistance, it may be necessary to consider preheating conditions (heating time, etc.) to some extent. Recognize.

When a Cu film or the like is formed as an adhesion layer as in Production Examples 1 and 2 of Patent Document 3, the Cu film may be oxidized in a high-temperature and high-humidity environment, and film peeling may occur.
In this regard, as in Example 10, it can be seen that when an oxide layer is formed as the adhesion layer, the adhesion is excellent. It can be seen that it is useful to form an oxide layer as the adhesion layer in order to improve the adhesion between the substrate and the reflective layer.

DESCRIPTION OF SYMBOLS 10 Reflective mirror 12, 14 Reflecting surface 20 Base material 30 Reflective film 31 Adhesion layer 32 Reflective layer 33 Increasing reflective layer 40 Deposition source 42 Shutter

Claims (6)

In a method for producing a reflective film including at least a reflective layer,
In the step of forming the reflective layer, AgBi is vapor-deposited as a raw material, and the composition ratio of Bi of the raw material is 0.01 to 0.8 atomic%. In the manufacturing method of the reflective film according to claim 1,
The composition ratio of Bi of the raw material is 0.02 to 0.05 atomic%. In the manufacturing method of the reflecting film according to claim 1 or 2,
Preheating a vapor deposition source containing the raw material;
Main heating the vapor deposition source at a temperature higher than the preheating;
A method for producing a reflective film, comprising: In the manufacturing method of the reflecting film according to claim 1 or 2,
In the step of forming the reflective layer,
A first step of vapor deposition with the shutter closed;
A second step of depositing after opening the shutter after the first step;
A method for producing a reflective film, comprising: In the manufacturing method of the reflective film as described in any one of Claims 1-4,
Comprising a step of forming an adhesion layer before the step of forming the reflective layer;
In the step of forming the adhesion layer,
A method of manufacturing a reflective film, comprising forming a layer of a material selected from at least one of LaTiO ₃ , CeO ₂ , Y ₂ O ₃ and SnO ₂ . In the manufacturing method of the reflective film according to any one of claims 1 to 5,
Comprising a step of forming an increased reflection layer after the step of forming the reflection layer,
In the step of forming the increased reflection layer,
A high refractive index material layer of a high refractive index material selected from at least one of TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , LaTiO ₃ , ZrO ₂ and a mixed material of these materials as the high refractive index material. Forming, and
Forming a low refractive index material layer of a low refractive index material selected from at least one of SiO ₂ and a mixed material obtained by mixing aluminum oxide with SiO ₂ as a low refractive index material;
A method for producing a reflective film, comprising:

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