JPH07110401A - Optical member and production thereof - Google Patents

Abstract

PURPOSE:To form an optical film layer on a substrate by sputtering by using aluminum fluoride (AlF3) as a target and using gas containing oxygen atom as a process gas. CONSTITUTION:A single layer antireflection film comprising a mixture film of AlF3 and Al2O3 is formed on a glass substrate. A glass substrate having 1.52 refractive index is set in a vacuum chamber, which is evacuated to 1X10<-5>Torr. Then Ar gas and O2 gas of 2X10<-3>Torr and 1X10<-3>Torr partial pressure, respectively, are introduced into the chamber. AlF3 is used as a target to form a film on the glass substrate by high frequency sputtering. The obtd. antireflection film has 1.4 refractive index and the compsn. of AlF3 and Al2O3 by 80atm.% and 20atm.%, respectively, analyzed by X-ray photoelectron spectroscopy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optical member having an optical film having a low refractive index of 1.45 or less and an optical film including an optical film layer having a low refractive index of 1.45 or less. The present invention relates to an optical member formed with the optical film.

[0002]

2. Description of the Related Art Conventionally, when an optical thin film such as an antireflection film or a half mirror is formed on an optical component, a vacuum evaporation method has been mainly used in which a film forming material is heated by an electron beam or the like and attached to a substrate. . In this case, magnesium fluoride (MgF
₂ ) or other low refractive index material, zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), titanium oxide (TiO ₂ ) or other high refractive index material, or a combination thereof. It is composed of a multilayer film.

However, in recent years, there has been a demand for more efficient production. Therefore, even in the case of these optical thin films, mass productivity and labor saving of processes are improved as compared with the vacuum deposition method.
The demand for coating by the sputtering method, which is advantageous in terms of quality stability and low cost, has increased.

Among them, as a method of forming an optical thin film having a low refractive index of 1.45 by a sputtering method, for example, a method disclosed in Japanese Patent Laid-Open No. 4-289165 is known. That is, an alkaline earth metal fluoride film such as MgF ₂ and an inert gas such as Ar and C
This is a method of sputtering using a mixed gas with a fluorine-based gas such as F ₄ .

[0005]

However, in the vacuum deposition method, MgF ₂ most commonly used as a low refractive index material is used.
When a film is formed by a sputtering method, the composition of the film deviates from the stoichiometric ratio and becomes a Mg-rich film, so absorption occurs in the film, and in order to solve this, JP-A-4-28 is known.
Absorption does not completely disappear even when the method using a fluorine-based gas is used as in Japanese Patent No. 9165, and furthermore, there is a drawback that exhaust equipment becomes complicated and expensive due to the use of a fluorine-based gas that is dangerous to the human body. It was

The present invention has been made in view of the above problems of the prior art. A film having a low refractive index of 1.45 or less and no absorption in the visible region is provided with a toxic gas such as a fluorine-based gas. An object of the present invention is to provide a method for manufacturing an optical member formed by a sputtering method without using it and an optical member.

[0007]

In order to solve the above-mentioned problems, the optical member manufacturing method of the present invention uses aluminum fluoride (AlF ₃ ) as a target for film formation, and uses argon or the like as a process gas. An optical film layer was formed on the substrate by a sputtering method using a gas containing at least an inert gas and a gas having an oxygen atom such as O ₂ or CO ₂ . Further, the optical member of the present invention is formed by providing an optical film including an optical film layer formed by the method described in claim 1 or an optical film including at least one optical film layer.

[0008]

According to the above construction, as the substance having a refractive index of 1.45 or less, AlF ₃ having a relatively small deviation from the stoichiometric ratio of the film formed by sputtering is used as the target, and further, by sputtering. The Al-rich film is promoted to oxidize by oxygen plasma and Al
By using a mixed film of F ₃ and Al ₂ O ₃ , it is possible to obtain a low refractive index film that does not absorb light.

[0009]

Example 1 The optical member of Example 1 was prepared by applying A on a glass substrate.
A single-layer antireflection film made of a mixed film of IF ₃ and Al ₂ O ₃ was provided. The optical thickness nd of the antireflection film is 13
It was set to 0 nm.

The above antireflection film was formed as follows. First, a glass substrate having a refractive index of 1.52 was set in a vacuum chamber, and the interior of the vacuum chamber was evacuated to 1 × 10 ⁻⁵ Torr. Then, Ar gas with a partial pressure of 2 × 10 ⁻³ Torr and 1 respectively. O ₂ gas of × 10 ^-3 Torr was introduced into the vacuum chamber. The substrate is not heated and the target is AlF ₃
Was used to form a film on a glass substrate by a high frequency sputtering method with an input power of 100 W. Observation of the plasma during the film formation with a plasma monitor revealed that fluorine and oxygen plasmas were present.

The reflectance of the antireflection film according to this embodiment is shown in FIG.
Shown in. When the refractive index of this antireflection film was examined, it was 1.4. In addition, X-ray photoelectron spectroscopy (X-Ray
Composition analysis using Photoelctron Spectroscopy) showed that AlF ₃ and Al ₂ O ₃ each contained 80%
And 20% (atomic percent).

As described above, according to this example, the antireflection film had good optical characteristics, and all the antireflection films were transparent and no absorption was observed in the visible region.

[0013]

Example 2 The optical member of this example was constructed by forming an antireflection film consisting of five layers on a polycarbonate substrate.
The film composition is AlF ₃ (0.09λ) / ZrO from the substrate side.
₂ (0.06λ) / AlF ₃ (0.09λ) / ZrO ₂
(0.49λ) / AlF ₃ (0.23λ). Here, the optical thickness is in parentheses, but the design wavelength λ = 550n
m.

The antireflection film was formed as follows. First, a polycarbonate substrate was set in a vacuum chamber, and the interior of the vacuum chamber was evacuated to 1 × 10 ⁻⁵ Torr. Then, Ar gas with a partial pressure of 2 × 10 ⁻³ Torr and 1 × 10 ⁻³ Torr, respectively. It was introduced into the vacuum chamber of the CO ₂ gas. The substrate is not heated and the target is AlF ₃
And ZrO ₂ were used to form an antireflection film having the above film structure on a glass substrate by a high frequency sputtering method with an input power of 100 W.

The reflectance of the antireflection film according to this embodiment is shown in FIG.
Shown in. Further, when the compositional analysis was performed in the same manner as in Example 1, each AlF ₃ layer contained AlF ₃ and Al ₂ O _{3 in} a proportion of 90% and 10% (atomic percent), respectively.

As described above, according to this example, the antireflection film had good optical characteristics, and all the antireflection films were transparent and no absorption in the visible region was observed.

[0017]

Example 3 The optical member of this example was constructed by providing a half mirror film consisting of 7 layers on an amorphous polyolefin resin substrate. The film composition is WO ₃ (0.
61λ) / AlF ₃ (0.34λ) / WO ₃ (0.27
λ) / AlF ₃ (0.36λ) / WO ₃ (0.27λ)
/ AlF ₃ (0.38λ) / WO ₃ (0.49λ). Here, the film thickness in parentheses is the design wavelength λ =
550 nm.

The antireflection film was formed as follows. First, an amorphous polyolefin resin substrate was set in a vacuum chamber, and the interior of the vacuum chamber was evacuated to 1 × 10 ⁻⁵ Torr. Then, the partial pressure was 2 × 10 ⁻³ Torr.
And Ne gas and 1 × 10 ⁻³ Torr O ₂ gas were introduced into the vacuum chamber. The substrate is not heated, and AlF ₃ and WO ₃ are used as targets to input power of 10
The half mirror film having the above film structure was formed on the substrate by a 0 W high frequency sputtering method.

FIG. 3 shows the reflectance when the half mirror film in this embodiment is formed on a prism and then the prism is attached to form a cube prism, which is incident at an incident angle of 45 °. Further, when the composition analysis was performed in the same manner as in Example 1 above, it was found that each AlF ₃ layer had AlF ₃
And Al ₂ O ₃ were contained in the proportions of 80% and 20% (atomic percentage), respectively.

As described above, according to this example, the half mirror film had good optical characteristics, and the antireflection films were all transparent and no absorption was observed in the visible region.

[0021]

As described above, according to the present invention, AlF
_{By using 3} (aluminum fluoride) as a target and using a gas containing oxygen atoms as at least a process gas, oxidation is promoted by oxygen plasma and AlF
_{By using} a mixed film of ₃ and Al ₂ O ₃ , a low-refractive-index film without absorption can be formed on a substrate by a highly productive sputtering method without using a toxic gas such as a fluorine-based gas as a process gas. It is possible to obtain an optical member having a film formed thereon.

[Brief description of drawings]

FIG. 1 is a diagram showing the reflectance of an antireflection film in Example 1 of the present invention.

FIG. 2 is a diagram showing the reflectance of an antireflection film in Example 2 of the present invention.

FIG. 3 is a diagram showing the reflectance of a half mirror film in Example 3 of the present invention.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Ken Kawamata 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Inventor Nobuaki Mitamura 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Yoshiki Nitta 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Toshiaki Ikumizu 2-43 Hatagaya, Shibuya-ku, Tokyo No. 2 Olympus Optical Co., Ltd. (72) Inventor Nobuyoshi Toyohara 2-34-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (2)

[Claims] 1. A method for manufacturing an optical member, which comprises forming an optical film layer on a substrate by sputtering using aluminum fluoride as a target and using a gas containing an inert gas and an oxygen atom as at least a process gas. . 2. An optical member comprising an optical film comprising an optical film layer formed by the method according to claim 1 or an optical film including at least one optical film layer.