JP2000171609A - Vapor deposition material for optical thin film having medium refractive index and optical thin film using that vapor deposition material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor deposition material for an optical thin film having a medium refractive index, and to provide the optical thin film having the medium refractive index and good quality by vapor deposition using the above- mentioned vapor deposition material. SOLUTION: Samarium oxide(Sm2O3) and aluminum oxide(Al2O3) are mixed in a desired molar ratio (Sm/Al), preferably >=0.3 molar ratio, and the mixture is sintered or fused and solidified in vacuum or in air at a temp. lower than the melting point to obtain a compd. expressed by the chemical formula of Sm1-xAl1+xO3 (-1<x<1) for the vapor deposition material of an optical thin film having a medium refractive index. By using this vapor deposition material, an optical thin film having a medium refractive index ranging from 1.65 to 1.9 is formed by vapor deposition on a substrate in vacuum. Since the compsn. ratio in the film is stable, continuous vapor deposition by successively replenishing the source material is possible. The obtd. thin film does not show significant absorption or decrease in transmittance due to white turbidity, and the obtd. optical thin film has excellent optical characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor deposition material for forming an optical thin film and an optical thin film formed by vapor deposition using the vapor deposition material, and more particularly to a lens, disk or glass substrate made of resin and glass and resin. The present invention relates to a vapor deposition material suitable for forming an optical thin film having an intermediate refractive index and a multilayer thin film including the optical thin film on an optical element composed of layers, and an optical thin film formed by vapor deposition using the vapor deposition material.

[0002]

2. Description of the Related Art Conventionally, in a camera, video, or other optical equipment, for example, in order to add an optical function to a lens or disk made of resin and glass, or an optical element made of a glass substrate and a resin layer, In order to increase or decrease the reflection of light and to absorb or transmit a specific wavelength, various optical multilayer thin films are provided. In the design of these optical multilayer thin films, materials for optical thin films having various refractive indexes are used, and aluminum oxide (Al) having a refractive index of about 1.65 is used.
₂ O ₃ ) and zirconia (ZrO) having a refractive index of about 2.0.
₂ ) Substances and mixtures that can provide an intermediate refractive index between
Silicon monoxide (SiO), magnesium oxide (MgO),
Lead fluoride (PbF ₂ ) or US Pat.
No. 961 discloses aluminum oxide (Al ₂ O).
₃ ) and zirconium oxide (ZrO ₂ ), a mixture of lanthanum oxide (L) disclosed in JP-A-6-184730.
a ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ).

[0003]

However, the above-mentioned substances and mixtures used to provide an intermediate refractive index (about 1.6 to 1.9) have the following problems as optical thin films. And there was substantially no substance or mixture suitable as an optical thin film having an intermediate refractive index.

[0004] That is, silicon monoxide (SiO) has a problem that absorption is generated in a thin film and the transmittance is lowered. Magnesium oxide (MgO) reacts with water or carbon dioxide in the air. There is a problem that it changes to magnesium hydroxide or magnesium carbonate to cause cloudiness (so-called burn), and lead fluoride (PbF ₂ ) has a problem of environmental pollution due to lead.

Further, a mixture of aluminum oxide (Al ₂ O ₃ ) and zirconium oxide (ZrO ₂ ) has good reproducibility of the refractive index, but causes a composition deviation in the material due to a difference in vapor pressure, resulting in cost reduction. There is a problem that continuous vapor deposition cannot be performed by adding an advantageous material, and a mixture of lanthanum oxide (La ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ) reacts with lanthanum oxide in the mixture with water in the air. There is a problem that lanthanum hydroxide causes expansion and causes the molded body to collapse, and fine particles are generated due to scattering when dissolving the chemical by disintegrating and becoming powdery, Further, there is a problem that a composition shift in the film material occurs during the deposition.

As described above, it can be said that various vapor deposition materials have been conventionally used as a substance or a mixture capable of giving a medium refractive index between alumina (about 1.65) and zirconia (about 2.0). In addition, it had unfavorable characteristics as a vapor deposition material, such as composition deviation and absorption during vapor deposition.

In view of the above, the present invention has been made in view of the above-mentioned various problems in the conventional optical thin film and vapor deposition material having an intermediate refractive index. It is possible to continuously vapor-deposit, and to provide a vapor deposition material for optical thin film of good quality, and to use optical thin film and multilayer thin film of good quality to be formed by vapor deposition using the vapor deposition material, and to use these optical thin films. It is an object to provide an optical element.

[0008]

SUMMARY OF THE INVENTION The present inventors have found that the refractive index between aluminum oxide (Al ₂ O ₃ ) having a refractive index of about 1.65 and zirconia (ZrO ₂ ) having a refractive index of about 2.0. As for the optical thin film having an intermediate refractive index (approximately 1.6 to 1.9) and its vapor deposition material, as a result of intensive studies on various materials in order to solve the above-mentioned problems, samarium oxide (Sm ₂ O ₃ ) is less basic than lanthanum oxide (La ₂ O ₃ ) or praseodymium oxide (Pr ₂ O ₃ ) which has been conventionally used, so that it is less likely to become a hydroxide, and aluminum oxide (Al) _Two
Based on the finding that the hydroxide of hardly occurs when a solid solution with O _3), formed with an optical thin film by a vapor deposition material consisting of samarium oxide (Sm ₂ O ₃₎ and aluminum oxide (Al ₂ O ₃₎ By forming the film, the refractive index of the optical thin film can be selectively set in the range of 1.65 to 1.9 by changing the composition ratio, and the composition ratio in the thin film is stable. The inventors have found that continuous vapor deposition can be performed by replenishment, and furthermore, no decrease in transmittance due to absorption or white turbidity is observed, and the present invention has been completed.

That is, the vapor deposition material for an optical thin film having an intermediate refractive index according to the present invention is characterized in that the composition can be represented by a compound represented by the chemical formula Sm _1-x Al _{1 + x} O ₃ (here, −1 <x <1). Can be formed by sintering a mixture of samarium oxide and aluminum oxide at an arbitrary molar ratio in a vacuum or in the air at a temperature equal to or lower than the melting point, and more preferably, samarium oxide and aluminum oxide are mixed in a molar ratio. The mixture can be formed by sintering a mixture mixed so that the ratio (Sm / Al) becomes 0.3 or more at a temperature equal to or lower than the melting point in a vacuum or the atmosphere.

The optical thin film of the present invention having an intermediate refractive index has a chemical formula of Sm _1-x Al _{1 + x} O ₃ (here, −1
<X <1), characterized in that it can be represented by the compound of <1.
It can be formed on a substrate by vapor deposition in a vacuum using the vapor-deposition material for an optical thin film according to any one of (3) to (3).

Further, the multilayer thin film of the present invention is characterized by comprising at least one optical thin film according to claim 4 or 5, and the optical element of the present invention is characterized in that the optical thin film according to claim 4 or 5 or A multilayer thin film according to claim 6 is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The deposition material for an optical thin film having an intermediate refractive index of 1.65 to 1.9 according to the present invention is a metal oxide containing samarium (Sm) and aluminum (Al) as metal elements. Samarium oxide (Sm ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ) are mixed at an arbitrary composition ratio, more preferably, in a molar ratio of 0 to aluminum oxide in the sense that the film composition is stable. 3. Mix to contain at a ratio of 3 or more, and form by sintering or melting and solidifying. The composition of this vapor deposition material has the chemical formula Sm _1-x Al
_{1 + x} O ₃ (here, −1 <x <1).

The sintered body and the like are manufactured by mixing samarium oxide powder and aluminum oxide powder in the above-mentioned arbitrary composition ratio, press-molding the mixture, and then, in a vacuum or in the air, having a melting point of about 1500 or less. Obtained by sintering at ℃. After sintering, pulverization is performed to produce a granular deposition material of 1 to 3 mm.

The sintered bodies of these vapor deposition materials are melted and evaporated mainly by an electron gun, and formed as an optical thin film on a target substrate. Although the sintered body is mainly melted by an electron gun, a resistance heating method, a high frequency method, or the like can be used.

In the vapor deposition material for an optical thin film of the present invention, by changing the composition ratio of samarium oxide and aluminum oxide, the optical thin film formed by the vapor deposition material can be set to an arbitrary intermediate refractive index. The refractive index can be selectively set in the range of 1.65 to 1.9. Furthermore, the composition ratio in the optical thin film is stable, continuous vapor deposition can be achieved by adding materials, and there is no noticeable absorption or white turbidity, and there is no generation of fine particles due to scattering of chemicals. And it is easier to process and use.

In the present invention, the substrate on which the optical thin film is formed is not particularly limited. In addition to optical glass serving as a substrate for a prism, a filter, and the like,
Examples include display CRTs, glasses, and cameras.

Furthermore, by forming an optical multilayer thin film by laminating an optical thin film having an intermediate refractive index according to the present invention with other optical thin films having various refractive indexes, a multilayer thin film excellent in various optical characteristics can be obtained. It goes without saying that it can be obtained.

[0018]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. Note that the present invention is not limited to these examples.

(Example 1) Samarium oxide (Sm ₂ O)
₃ ) powder and aluminum oxide (Al ₂ O ₃ ) powder,
Sm and Al were mixed at a molar ratio (Sm / Al) of 1 and press-molded. Then, the mixture was sintered in a vacuum of 1 × 10 ⁻⁴ Torr or less for about 4 hours at a melting point of 1500 ° C. or less. This was followed by pulverization to produce a granular deposition material of 1 to 3 mm.

Next, a vacuum evaporation machine (BMC manufactured by SYNCHRON)
850) is filled with the above-mentioned deposition material in an electron beam evaporation hearth, and the inside of the apparatus is evacuated to a pressure of 1 × 10 ⁻⁵ Torr. Then, oxygen gas is introduced into the 1 × 10 ⁻⁴ Torr apparatus. After heating and melting the deposition material by an electron beam having an acceleration voltage of 8 KV and an emission current of 400 mA,
An optical film having an optical film thickness of λ / 4 is set on an object to be deposited made of glass previously set in an apparatus and heated to a temperature of about 300 ° C.
(Λ = 480 nm) is deposited at a deposition rate of about 10 ° / sec. This deposition was continuously performed 10 times on different substrates. FIG. 1 shows the refractive index calculated from the peak value of the spectral characteristics of each optical thin film and the samarium concentration (wt% in terms of oxide) of the film by X-ray fluorescence analysis. The wavelength dispersion of the absorptance at the first and tenth vapor depositions is shown in FIGS. 2A and 2B, respectively. Further, the formed optical thin film was subjected to a weather resistance test (60 ° C., humidity 95%, 100 hours) in a thermo-hygrostat, and it was visually confirmed whether cloudiness or burn was generated.

As a result, the refractive index and the samarium concentration in the film are stable as shown in FIG. 1 and no absorption is observed as shown in FIG. No absorption or clouding was observed after the weather resistance test.

Example 2 Samarium oxide (Sm ₂ O)
₃ ) powder and aluminum oxide (Al ₂ O ₃ ) powder,
The molar ratio of Sm and Al (Sm / Al) were mixed to 0.5, after press forming, 1 × 10 ^-4 Torr or less to about in a vacuum for 4 hours, calcined at 1500 ° C. is lower than the melting point Knotting was performed and then pulverized to produce a granular deposition material of 1 to 3 mm.

Next, the optical thin film was successively vapor-deposited 10 times on different substrates in the same procedure as in Example 1, and the refractive index calculated from the peak value of the spectral characteristic of each optical thin film and the wavelength dispersion of the absorptance Was measured. The results are shown in FIGS. Further, a weather resistance test (60 ° C., humidity 95%, 100
Time), and visually checked whether cloudiness or burnt had occurred.

As a result, also in this embodiment, the refractive index is stable as shown in FIG. 3, and the absorption is not seen as shown in FIG. No absorption or clouding was observed after the weather resistance test.

Example 3 Samarium oxide (Sm ₂ O)
₃ ) powder and aluminum oxide (Al ₂ O ₃ ) powder,
Mixing was performed so that the molar ratio of Sm to Al (Sm / Al) becomes 0.33, press-molded, and then fired in a vacuum of 1 × 10 ⁻⁴ Torr or less for about 4 hours at a melting point of 1500 ° C. or less. Knotting was performed and then pulverized to produce a granular deposition material of 1 to 3 mm.

Next, optical thin films were successively vapor-deposited 10 times on different substrates in the same procedure as in Example 1, and the refractive index calculated from the peak value of the spectral characteristics of each optical thin film and the wavelength dispersion of the absorptivity. Was measured. The results are shown in FIG. 3 and FIG. Further, the formed optical thin film was subjected to a weather resistance test (60 ° C., humidity 95%, 100 hours) in a thermo-hygrostat, and it was visually confirmed whether cloudiness or burns had occurred.

As a result, also in this embodiment, the refractive index is stable as shown in FIG. 3, and the absorption is not seen as shown in FIG. No absorption or clouding was observed after the weather resistance test.

Example 4 Samarium oxide (Sm ₂ O)
₃ ) powder and aluminum oxide (Al ₂ O ₃ ) powder,
After mixing and press-molding the mixture so that the molar ratio of Sm and Al (Sm / Al) becomes 1, sintering is performed at 1500 ° C. for about 4 hours in a vacuum of 1 × 10 ⁻⁴ Torr or less, and then pulverized And a granular deposition material having a thickness of 1 to 3 mm.

Using this vapor deposition material, continuous vapor deposition was performed five times in the same procedure as in Example 1. Thereafter, the vapor deposition material was added to a hearth for electron beam vapor deposition, and the continuous vapor deposition was performed again five times. With respect to the formed optical thin film, the refractive index calculated from the peak value of the spectral characteristics and the samarium concentration (in terms of oxide, wt%) in the film were measured by X-ray fluorescence analysis.

As a result, also in this embodiment, the refractive index before and after the addition of the vapor deposition material was stable, and the samarium concentration in the film was also stable.

Comparative Example 1 Lanthanum Oxide (La ₂ O ₃ )
Powder and aluminum oxide (Al ₂ O ₃ ) powder
And Al were mixed at a molar ratio (La / Al) of 1 and press-molded, sintered at 1500 ° C. for about 4 hours in a vacuum of 1 × 10 ⁻⁴ Torr or less, and then pulverized. 1
A granular deposition material of ３3 mm was produced.

Next, a hearth for electron beam evaporation arranged in a vacuum evaporation machine is filled with the above-mentioned evaporation material, and the inside of the apparatus is 1 ×.
After evacuating to a pressure of 10 ^-5 Torr, oxygen gas was
^-4 Torr Introduced into a Torr apparatus, the deposition material was heated and melted by an electron beam with an accelerating voltage of 8 KV and an emission current of 400 mA, and then set in the apparatus and heated to a temperature of about 300 ° C. An optical thin film having an optical film thickness of λ / 4 (λ = 480 nm) is continuously deposited on a different substrate at a deposition rate of about 10 ° / sec.
Deposited once. FIG. 1 shows the refractive index calculated from the peak value of the spectral characteristic of each optical thin film and the lanthanum concentration (in terms of oxide, wt%) in the film by X-ray fluorescence analysis.

In this comparative example, as shown in FIG. 1, the refractive index was not stable for each number of depositions, the lanthanum concentration in the film tended to decrease, and an optical thin film having a stable refractive index was formed. The result was not suitable to do.

Comparative Example 2 Magnesium oxide (MgO)
Was press-molded, sintered at 1500 ° C. for about 4 hours in the air, and then pulverized to produce a granular deposition material of 1 to 3 mm. Then, an optical thin film was deposited in the same procedure as in Example 1. After that, the weather resistance test (6
(0 ° C., humidity 95%, 100 hours), and it was visually confirmed whether cloudiness or burns had occurred. As a result, the optical thin film in this comparative example became cloudy and was not suitable for optical use.

[0035]

As described above, according to the present invention, a mixture of samarium oxide and aluminum oxide provides:
A vapor deposition material for an optical thin film having an intermediate refractive index in the range of 65 to 1.9 can be obtained. Further, in the optical thin film to be formed, the refractive index changes the composition ratio of samarium oxide and aluminum oxide. From 1.65 to 1.9
In addition, since the composition ratio in the optical thin film is stable, continuous vapor deposition can be performed by adding materials, and the optical thin film to be formed has a remarkable absorption or absorption. No turbidity is observed, no fine particulate matter is generated due to scattering of chemicals, and processing and use are facilitated.

As described above, the vapor deposition material for an optical thin film of the present invention is different from a material which has been conventionally used for forming an optical thin film having a refractive index in the range of 1.65 to 1.9, in that it absorbs or becomes cloudy. The transmittance does not decrease, and there is no effect on environmental pollution.

[Brief description of the drawings]

FIG. 1 is a diagram showing changes in the refractive index and the film composition ratio during continuous deposition of a deposited film of samarium oxide and aluminum oxide according to the present invention, and a deposited film of lanthanum oxide and aluminum oxide as a comparative example.

FIGS. 2 (a) and 2 (b) are diagrams showing the wavelength dispersion of the absorptance at the first and tenth depositions in a deposited film of samarium oxide and aluminum oxide according to the present invention.

FIG. 3 shows that during the continuous deposition of a deposited film of samarium oxide and aluminum oxide according to the present invention, the molar ratio of samarium to aluminum (Sm / Al) is 0.5 and 0.3.
It is a figure which shows the change of the refractive index in the case of being set to 3.

FIG. 4 is a graph showing the wavelength dispersion of the absorptivity when the molar ratio of samarium to aluminum (Sm / Al) is 0.5 in the deposited film of samarium oxide and aluminum oxide according to the present invention.

FIG. 5 is a graph showing wavelength dispersion of absorptivity in a deposited film of samarium oxide and aluminum oxide according to the present invention when the molar ratio (Sm / Al) of samarium to aluminum is 0.33.

Continued on front page F-term (reference) 2K009 AA02 CC03 DD03 4G059 AA01 AC04 EA01 EA07 EB03 4K029 AA09 AA24 AA25 AA27 BA43 BA50 BB01 BB02 BC07 DB05 DB10

Claims (7)

[Claims] 1. A deposition material for an optical thin film having an intermediate refractive index, wherein the composition can be represented by a compound having a chemical formula of Sm _1-x Al _{1 + x} O ₃ (here, −1 <x <1). 2. The method according to claim 1, wherein samarium oxide and aluminum oxide are mixed at an arbitrary molar ratio, and the mixture is formed by sintering the mixture in a vacuum or in the air at a temperature lower than the melting point. Vapor deposition material for optical thin films with intermediate refractive index. 3. Mixing samarium oxide and aluminum oxide so that the molar ratio (Sm / Al) becomes 0.3 or more;
The vapor deposition material for an optical thin film having an intermediate refractive index according to claim 1, wherein the mixture is formed by sintering the mixture in a vacuum or in the air at a temperature equal to or lower than a melting point. 4. An optical thin film having an intermediate refractive index, whose composition can be represented by a compound having a chemical formula of Sm _1-x Al _{1 + x} O ₃ (here, −1 <x <1). 5. An optical thin film having an intermediate refractive index, which is formed by vapor deposition in a vacuum on a substrate using the optical thin film deposition material according to claim 1. 6. A multilayer thin film comprising at least one optical thin film according to claim 4. 7. An optical element comprising the optical thin film according to claim 4 or the multilayer thin film according to claim 6.