JPS63192856A - Production of yttrium oxide composition for vapor deposition and antireflection film - Google Patents

Abstract

PURPOSE:To produce a chemically stable durable vapor-deposited film having superior antireflection performance by using yttrium oxide for vapor deposition contg. titanium oxide and zirconium oxide. CONSTITUTION:Yttrium oxide for vapor deposition is mixed with about 0-7.3wt.% titanium oxide and 0-90wt.% zirconium oxide and the mixture is tabletted and sintered. A vapor-deposited film is formed on a substrate of silicon or a III-V compd. semiconductor such as GaAs with the resulting yttrium oxide compsn. The refractive index of the compsn. is closed to 1.87 as the theoretically required value, so the surface reflectance of the substrate can be made nearly zero. Since the vapor-deposited film hardly undergoes change with the lapse of time, the service life can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a yttrium oxide composition for vapor deposition and a method for producing an antireflection film.

[Conventional technology]

Conventionally, for example, AppN, Phys, Lett, VoL, 4
7. No. 5, page 450 and Applied Qpt.
ics, Vol. 23. As shown in No. 1, page 161, ZrOx is used as a vapor deposition material when forming an antireflection film on elements made of St or GaAs.
Ordinarily, Si3N4 is used. The refractive index of these elements is 3.5, and the required value of the refractive index of the antireflection film is theoretically f,5=1.87.

Vapor deposition materials that almost satisfy 1.87 are Zr(h) and Si3N4.The bulk refractive index of these materials is 2.05 and 1.98, respectively, but when forming a thin film, the vapor deposition conditions must be adjusted. Accordingly, the refractive index n=1
．． 87 can be obtained. Regarding this fact, T.
L, Paoli, Appl, Phys, Let
t, 47(5), 450 (1985), p. 450 and G. Eisenstein, AppCOpti.
CS, 23(1), 161 (1984), p. 162.

[Problem that the invention seeks to solve]

When an antireflection film is formed on Si or GaAs using a conventional vapor deposition composition such as ZrO2 or Si3N4, it is possible to reduce the reflectance to zero, but the change characteristics of the reflectance over time are In this way, although the initial properties of conventional compositions satisfy the specifications, they have the drawback of large changes over time.

The present invention was made to solve the above problems, and
An object of the present invention is to provide a yttrium oxide composition for deposition.

Still another object is to provide a method and material for producing a deposited film that is chemically stable, durable, and has excellent antireflection performance.

[Means for solving problems]

The yttrium oxide composition for vapor deposition according to the present invention contains titanium oxide and zirconium oxide. In addition, a method for manufacturing an antireflection film according to another invention includes titanium oxide and zirconium oxide! This method uses yttrium oxide for vapor deposition.

[Effect]

The yttrium oxide composition for vapor deposition according to the present invention has a refractive index close to the theoretically required value of 1.87, and changes over time are also small.

〔Example〕

When considering vapor deposition materials necessary for forming antireflection films on GaAs and Si, Y2 was selected as a material with little change over time.
It turns out that O3 is superior. However, since its refractive index is rather small and not optimal, it was decided to avoid using Y2O3 alone.

Therefore, attempts were made to obtain a desired material by combining it with a substance having a high refractive index. When trying to obtain a mixed film, it is desirable that the vapor pressures of each film be close to each other. This is because the structure of the vapor deposition material changes during vapor deposition.
Since h is approximately equal in the temperature range of 2300° C. to 2600° C., Y2O3 and Zr0z were used as the main mixed substances, and Ti0z was added to roughly correct the refractive index. TiO
2 reduces the heterogeneity of the structure in the film thickness direction, which is specific to ZrO2.

When the surface reflectance R is set to zero, changes in the surface reflectance R due to variations in the refractive index nf of the thin film become minimum.

That is, reducing the surface reflectance to zero is a necessary condition for obtaining an anti-rumination film that shows little change over time.

The surface reflectance R is the refractive index nf of the N film as shown in equation (1).
is a quadratic function of

In the case of air, n is the refractive index of the incident medium.
o=1. It is oo. nS is the refractive index of the substrate, GaAs
, then ns == 3.5.

Equation (1) can be simplified to form (2).

RoC (nf -1,87) −・−・−・−・・
(21) As shown in equation (3), the rate of change of the surface reflectance R of the thin film due to the refractive index nf becomes smaller as nf approaches 1.88.

The surface reflectance R (%) obtained from nf Y2O3 alone is shown in FIG. 1 and Table 1.

Table 1 When designing a mixed film that provides a refractive index that satisfies the surface reflectance R of 0.25% or less, from Figure 1, formula (4) % Formula % From FIG. 2, nf that satisfies % or less is expressed by equation (5).

1.775 < nf < 1.992 −・・・−・
...(s+TiO2 that satisfies equations (4) and (5)
The mixing ratios of ZrO2 and ZrO2 are shown in Table 2 from FIG.

Table 2 Example 1 10% zirconium oxide by weight to yttrium oxide
, 1% titanium oxide was added, thoroughly mixed, and press-molded at a pressure of 5,000 liters, followed by open sintering at about 1,300° C. for about 3 hours to obtain tablets for vapor deposition tests. This reagent was then loaded into an electron gun located in the vapor deposition apparatus. After evacuating to a vacuum level of 5 x 10 Torr,
While paying attention to the glass substrate and the GaAs substrate, increase the output of the electron gun, raise the temperature of the tablet to dissolve it, and further increase the substrate temperature to 30017m until the optical film thickness reaches nd = 12011m. It was deposited with

The deposited film of this reagent deposited on a glass substrate has a refractive index n=
1.84, no absorption, strong adhesion to GaAs substrate, chemically stable and durable,
A very satisfactory thin film was obtained as an anti-reflection material in which the surface reflectance of the aAs substrate was approximately 0% and its initial characteristics were maintained over a long period of time.

Example 2 Zirconium oxide is added to yttrium oxide at a MATE ratio of 2
0% and 1.5% titanium oxide were added, and tablets were obtained in the same manner as in the previous example. When vapor deposition was performed on the end face of a GaAs-GaA7As laser diode at a substrate humidity of 120°C using the same method as in the above example, the reflectance of the laser light emitting surface became almost zero, resulting in a 5LD (Super
Luminescent Diode) Now exhibits characteristics as fg child.

This property lasts for a long time.

Comparative example: 20% zirconium oxide by weight to yttrium oxide
, 8% titanium oxide was added, and tablets were obtained in the same manner as in Example 1 above. GaAs-GaAnA was prepared using the same method as in Example 2 except that the substrate temperature was 120°C.
It was deposited on the end face of an S-based laser diode. As a result, the surface reflectance was approximately 1.2%, and the characteristics as an SLD element were not obtained.

From the above results, the amount of zirconium oxide contained in the yttrium oxide composition for deposition is 0 to 90% by weight, preferably 0 to 80% by weight, and the amount of titanium oxide is 0 to 7.3% by weight, preferably is 0.5 to 4.8% by weight.

As an example of application to other objects to be deposited, it can be used as an anti-reflection film for light emitting diodes, photodiodes, etc. made of Si halftone bodies.

In the above embodiments, the electron gun heating was described, but similar effects are expected as a sputtering target.

〔Effect of the invention〕

As described above, according to the present invention, the vapor deposition material is a mixed composition of yttrium oxide, zirconium oxide, and titanium oxide so that an antireflection film can be formed in accordance with the refractive index of a semiconductor made of Si or GaAs. , the surface reflectance of the object to be deposited can be reduced to almost zero. Furthermore, since there is little change over time, the operating time can be extended.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing the relationship between the refractive index of a thin film and the surface reflectance, and FIG. 3 is an explanatory diagram showing the relationship between the amount of TiQ2 mixed and the refractive index of the thin film.

Claims (5)

[Claims] (1) A yttrium oxide composition for vapor deposition characterized by containing titanium oxide and zirconium oxide. (2) The content of titanium oxide is 0% to 7.3% by weight,
The yttrium oxide composition for vapor deposition according to claim 1, characterized in that the content of zirconium oxide is 0% to 90% by weight. (3) The yttrium oxide composition for vapor deposition according to claim 1 or 2, characterized in that yttrium oxide, titanium oxide, and zirconium oxide are mixed and sintered into a tablet shape. (4) Using a yttrium oxide composition for vapor deposition containing titanium oxide and zirconium oxide, silicon or Ga
A method for producing an antireflection film, comprising producing a thin film of a III-V compound semiconductor such as As. (5) The method for producing an antireflection film according to claim 4, wherein the yttrium oxide composition is heated with an electron gun.