JPS59148002A - Zirconium oxide composition for vapor deposition and sputtering and production of optical thin film using said composition - Google Patents

Abstract

PURPOSE:To suppress optical heterogeneity and to improve hardness by using a compsn. consisting of zorconium oxide as well as yttrium oxide and titanium oxide for an evaporating source or sputtering source. CONSTITUTION:A compsn. consisting of zirconium oxide, 0.5-50wt% yttrium oxide by the weight of said zirconium and 0.5-160wt% titanium oxide is used for an evaporating source or sputtering source and a thin film is formed on the surface of a base body by vacuum evaporation or sputtering.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zirconium oxide composition for vapor deposition and sputtering, and a method for producing optical thin films using the same.

Conventionally, zirconium oxide has been used as a main film constituent material for optical multilayer films such as multilayer antireflection films.

That is, as a multilayer antireflection film for a substrate such as glass having a refractive index of about n=1.4 to 1.8, a high refractive index film having a refractive index of around 2.0 is required. Zirconium oxide has been the only suitable starting material for producing films by vapor deposition or sputtering.

However, the deposited film of zirconium oxide exhibits optical inhomogeneity in that the refractive index in the film thickness direction gradually decreases from the substrate side to the surface side, and this phenomenon affects the effectiveness of multilayer antireflection coatings. It had the major drawback of hindering the

Such optical inhomogeneity occurs because crystallization progresses as the film fills up, crystal grains grow larger near the surface, and at the same time, the film density becomes coarser, resulting in n of the film near the surface than near the substrate.
This is thought to be due to a decrease in

Therefore, in order to improve this, we mixed a small amount of a substance with a higher refractive index than zirconium oxide into the starting material.
It has been considered to increase the amount of high refractive index material mixed in as the vapor deposition progresses by utilizing the vapor pressure difference between the two, or to reduce the crystallinity of the zirconium oxide deposited film.

As a result of various studies on contaminants, it was found that the overall effect of incorporating titanium oxide is to reduce the optical heterogeneity of zirconium oxide deposited films, and it has already been put into practical use in some areas. There is.

However, it has become clear that the addition of titanium oxide causes various drawbacks.

That is, the refractive index of the zirconium oxide film becomes lower than that without the addition of titanium oxide, and the strength of the zirconium oxide film added with titanium oxide is lower than that without the addition of titanium oxide.

Therefore, the present invention has been made to eliminate such conventional drawbacks, and by simultaneously mixing yttrium oxide and titanium oxide into zirconium oxide, optical non-uniformity appearing in conventional zirconium oxide films can be suppressed, and It has the advantage that it can have even higher hardness than conventional zirconium oxide films, and can provide a high refractive index optical film for a multilayer antireflection film with extremely excellent properties.

That is, the zirconium oxide composition for vapor deposition and sputtering of the present invention is characterized by comprising zirconium oxide, 0.5 to 50% by weight of yttrium oxide, and 0.5 to 160% by weight of titanium oxide. be.

In the method for producing an optical thin film of the present invention, a composition consisting of zirconium oxide, 0.5 to 50% by weight of yttrium oxide, and 0.5 to 160% by weight of titanium oxide is used as an evaporation source or a sputtering source. It is characterized by forming a thin film on the surface of the substrate by vacuum evaporation or sputtering.

In the zirconium oxide composition for vapor deposition and sputtering of the present invention, yttrium oxide stabilizes the crystalline form of the film;
It also has the effect of reducing the increase in the refractive index of the film due to the addition of titanium oxide, and the amount of titanium oxide mixed is 0.5 to 50% by weight of zirconium oxide.

If the amount is less than 0.5% by weight, the effect of stabilizing the crystals and reducing the refractive index of the resulting film will be almost negligible, and if it exceeds 50% by weight, the refractive index of the resulting film will be significantly reduced. Too much is not preferable because it may even lead to chemical instability.

Titanium oxide has the effect of increasing the refractive index of the deposited film, and its amount is 0.5 to 160% that of zirconium oxide.
Weight%.

If the amount is less than 0.5% by weight, the resulting film will be largely non-uniform, and if it is added by 16060% by weight, the absorption in the visible light range will tend to be poor, which is not preferable.

Note that if zirconium oxide only contains yttrium oxide, the optical heterogeneity is slightly improved, but the improvement effect is insufficient and the strength of the formed film is also lower than that of yttrium oxide. On the contrary, it becomes smaller than in the case of
However, the refractive index of the film is also lower than that of a zirconium oxide film without addition of yttrium oxide.

The zirconium oxide composition of the present invention is usually used by sintering the above-mentioned predetermined amounts of zirconium oxide, yttrium oxide, and titanium oxide.

Next, in the method for producing an optical thin film of the present invention, the above-described zirconium oxide composition is used as an evaporation source or a sputtering source, and a thin film is formed on the surface of a substrate by vacuum evaporation or sputtering. Here, the shape of the base body is not particularly limited, and examples thereof include a glass plate, a lens, and the like.

The optical thin film obtained by this manufacturing method contains zirconium oxide, 0.5 to 50% by weight of yttrium oxide, and 0.5 to 160% by weight of nathane oxide.
Unlike conventional zirconium oxide films, optical non-uniformity such as a decrease in refractive index from the substrate side to the surface side does not occur. Furthermore, it is possible to reduce the increase in refractive index that occurs in a zirconium oxide film to which only acid and hichitanium are added.

Furthermore, the adhesion of the film to the substrate and the hardness of the film can be further increased compared to a film made of zirconium oxide alone, a zirconium oxide film to which only titanium oxide is added, and a zirconium oxide film to which only yttrium oxide is added.

In addition, in the zirconium oxide composition of the present invention, the amount of yttrium oxide mixed is adjusted within the range of 0.5 to 50% by weight, and the amount of titanium oxide mixed is adjusted within the range of 0.5 to 160% by weight. Accordingly, the refractive index of the obtained optical thin film can be changed.

Therefore, when manufacturing a multilayer anti-reflection film, the refractive index of the zirconium oxide film is adjusted to the desired optimum value in response to the change in the refractive index of the glass substrate, for example from 1.5 to 1.8. can do.

Therefore, according to the zirconium oxide composition of the present invention,
A high refractive index optical thin film for a multilayer antireflection film with extremely excellent properties can be obtained.

Hereinafter, the present invention will be explained in detail based on examples.

Example 1 Yttrium oxide powder and titanium oxide powder were added to zirconium oxide powder at a weight ratio of 8 g each, mixed thoroughly, and then press-molded at a pressure of about 300 Kf/d, and then heated at about 1300° C' for 2 hours. Fired to a diameter of 18 mm and a thickness of 7 mm.
A disc-shaped pellet of rhyme was obtained.

This pellet was placed in a crucible of a 2 kW electromagnetic deflection type electron beam evaporation source, and the vacuum level was 1.5 x 10-''f.
After evacuating to orr, a glass substrate (glass refractive index n
= 151) by electron beam heating on the surface
wtm deposition rate, and the optical film thickness nd (n = refractive index, d - film thickness) was λ/4 and λ/2 (λ-52On
Vapor deposition was continued until it reached +n).

When the refractive index of the vapor deposited film deposited on the glass substrate surface is determined from the maximum value of the spectral reflectance curve, n is 2.09 near the center of the visible region (wavelength 520 nm), and the absorption is also non-uniform. was also not recognized.

The adhesion to the substrate and the hardness of the film were also greater than those of the zirconium oxide film alone, the titanium oxide-added zirconium oxide film, and the yttrium oxide-added zirconium oxide film.

Example 2 Yttrium oxide powder and titanium oxide powder were added to zirconium oxide powder in a weight ratio of 18% and 30%, respectively, and pellets were obtained in the same manner as in Example 1.

When this pellet was used for vapor deposition in the same manner as in Example 1, a good film was obtained which similarly had high adhesion and film strength, and had no absorption or non-uniformity in refractive index.

On the other hand, the refractive index of this film was 2.19, which was larger than the M refractive index of Example 1 because the amount of titanium oxide added was greater than that of yttrium oxide.

This film had good properties as a high refractive index film for a multilayer antireflection film.

Furthermore, by repeating vapor deposition using the same composition, it is possible to improve the optical properties, adhesion, strength, etc. of the resulting film.
The percent properties were all stable, and excellent appearance properties were obtained.

Example 3 Indium oxide powder and titanium oxide powder were added to zirconium oxide powder at a weight ratio of 8% each, and after thorough mixing, the mixture was heated to a temperature of 1700°C and a pressure of 150°C using a hot press.
A disc body with a diameter of 17 cm and a thickness of 1 crn was manufactured at Kg/cft.

This disc body was used as a target and attached to a high frequency two-pole flat plate type sputtering device, and the spacing between the electrodes was set to 8c1n, and a glass plate of 5×10''3 Torr was placed on the opposite electrode surface.
Under the Ar gas pressure of r, the pressure was set to 2 KV, and the substrate temperature was set to 300 to 4 oO'C.
Press sputtering was carried out for 1 minute, then the sputter was opened and sputtering was carried out at 1 with nd of λ4 and λh.

As a result, as in Examples 1 and 2, a zirconium oxide film having excellent optical properties of 1# was obtained.

Sub-agent of the Director of the Agency of Industrial Science and Technology qrr Agent of Nippon Metal Chemical Co., Ltd. Patent attorney small river - Ken Teru Noguchi Kazuhiko Yushita

Claims (1)

[Scope of Claims] 1. A zirconium oxide composition for vapor-deposited spruce, comprising zirconium oxide, yttrium oxide in an amount of 15 to 50% by weight of zirconium oxide, and 0.5 to 160% by weight of titanium oxide. 2. Using a composition consisting of zirconium oxide, 0.5 to 50% by weight of yttrium oxide and 0.5 to 160% by weight of titanium oxide as an evaporation source or a sputtering source,
A method for producing an optical thin film, which comprises forming a thin film on the surface of a substrate by vacuum evaporation or sputtering.