JPS6287904A - Optical waveguide device and its manufacturing method - Google Patents

Abstract

PURPOSE:To decrease loss and to improve stability by providing a metal diffused layer down to a desired depth from the boundary of a chalcogenide glass layer in contact with a thin metallic film layer. CONSTITUTION:The chalcogenide glass layer 2 provided on a substrate 1 and the thin metallic film layer 3 formed on the chalcogenide glass layer are provided. This optical waveguide element 6 is provided with the metal diffused layer down to the desired depth from the boundary of the chalcogenide glass layer 2 in contact with the thin metallic film layer 3. Such optical waveguide element is formed by forming the chalcogenide glass layer 2 on the substrate 1, forming the thin metallic film 3 on the chalcogenide glass layer and irradiating an electron beam 4 onto the thin metallic film thereby forming the metal diffused layer 5 down to the desired depth from the boundary of the chalcogenide glass layer 2 in contact with the thin metallic film layer. The optical waveguide 5 having a low loss and good stability is thus easily and inexpensively formed with high accuracy.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an optical waveguide device and a method for manufacturing the same, and particularly relates to an optical waveguide device with good light confinement efficiency and excellent stability and a method for manufacturing the same. .

[Background of the invention]

Conventionally, optical waveguide devices are made by (a) depositing a single crystal thin film of LiNb01 or LiTaO3 on a substrate surface with a refractive index lower than that of these materials by vapor deposition or sputtering (
JP-A-57-85008) and (b) a LiNbO3 substrate in which Ti is diffused to form an optical waveguide (JP-A-57-88411) are known. In particular, the latter is generally widely used.

However, the TI ion diffusion temperature is around 1000℃,
When heat treated at such high temperatures, Li,
O diffuses outside. Then, the refractive index distribution of the optical waveguide widened, the confinement efficiency of the waveguide deteriorated, and propagation loss increased.

Furthermore, forming the optical waveguide described above requires high-temperature operation, and one photolithography step is required to form the Ti pattern. Therefore, many manufacturing steps are required, which poses a problem in productivity.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide an optical waveguide element that has low loss, good stability, and a simple manufacturing process, and a method for manufacturing the same.

[Summary of the invention]

The above purpose is to provide a substrate, a lath layer of chalcogenide formed on this substrate, and a metal thin film formed on this chalcogenide glass layer, and to have a desired depth from the interface of the chalcogenide glass layer in contact with the metal thin film layer. An optical waveguide element is provided with a metal diffusion layer over the entire length, a lath layer of chalcogenide is formed on a substrate of this optical waveguide element, a metal thin film is formed on this chalcogenide 127 layer, and an electron beam is irradiated onto this metal thin film. This is achieved by irradiating the chalcogenide to form a metal diffusion layer over a desired depth from the interface of the lath layer where it contacts the metal thin film layer.

The materials used in the present invention will be explained below. The substrate is (a) silicon such as single crystal silicon or polycrystalline silicon, (b) GaAs, InP, or InAs.
, (c) LiNb0. , LiT
An optical crystal material such as aO3, (d) silica-based glass such as quartz lath or Pyrex glass crown glass is used.

A chalcogenide lath is provided on the substrate.

Chalcogenide glass is a general term for amorphous materials containing at least one of sulfur, selenium, and tellurium. Specifically, Al1 S3, A128113
rAs3Sey, G@s4, A
+lff1 Tag, GoTo,
Go, 6As35Te26SH, CdSe, G
e52, Nurse, etc., the refractive index is 2.1
~3.1.

The chalcogenide lath film provided on the substrate is formed by vacuum evaporation, sputtering, or the like. The conditions for vacuum evaporation are: substrate temperature 5 to 100°C, degree of vacuum 1 x 10''4 to I
10-'wsHg, film-forming rate 10-too X/crown, preferably substrate temperature 40-60°C, vacuum degree I
X 10'' to I X 10-' wa Hg, and the film formation rate was 40 to 60X/concentration.

The conditions for 4-filling are almost the same as those for vacuum evaporation, and the film formation rate is 1 to 20X/Ig, preferably 2 to 20X/Ig.
It is IOX/8.

The metal film formed on the chalcogenide 127 layer formed on the substrate includes kt, Au, Ag, Cu,
T.I.

These include Nl and Cr. Among them, At, Au,
Ag.

Cu is particularly important because it is easy to form a thin film. Specifically, the substrate temperature is 25 to 90°C and the degree of vacuum is I X 10-' to I
0-' mHg.

Film formation rate: 2-100λ/'r Film thickness: 200-5000X, preferably 1, substrate temperature: 40-60'C, degree of vacuum: 5
X 10-' ~ I X 10-' mxHg, adult ML
The speed is 5-501/g, and the thickness is 500-3000.

The electron beam irradiated onto the metal thin film mentioned above has an acceleration voltage of 10
~500 kV, spot diameter O01~1μrrLK
It is focused and scanned into the desired waveguide shape. Or C
It is also possible to uniformly scan an electron beam with an accelerating voltage of 10 to 500 kV using a mask in which r, W, etc. are patterned with a desired waveguide shape. As a result of the above, the metal in the portion irradiated with the electron beam is diffused into the chalcogenide glass layer, and the refractive index of the chalcogenide plus in which the metal is diffused increases, making it possible to form a desired buried three-dimensional optical waveguide element. Note that unnecessary metal after electron beam irradiation is removed by etching.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 As shown in Fig. 1, a silicon single crystal with a thickness of 400 μm was used as the substrate 1, and this was maintained at 40'C and the degree of vacuum was 5X.
10″″’ tmHg, thickness 2μ at film formation rate 5X/8
As of m! A chalconide plus layer 2 manufactured by S1 was formed by sputtering. The refractive index of this chalcogenide glass was 2.41.

In addition, As2S3 chalconide glass has Am and S
The powder was heated to 800° C. in a vacuum to melt it, rapidly cooled to vitrify it, and then molded into a turbid.

Next, the above-mentioned force lucodanide is applied to the metal thin film layer 3 on the lath layer 2.
As a result, At was vacuum-deposited. Conditions are substrate temperature 50℃
, X transformation I X 10-' mHg, film formation rate 50
'L4゜film thickness is 1000 g.

Next, the metal thin film layer 3 was irradiated with an electron beam 4 having an acceleration voltage of 25 kV and a spot diameter of 0.5 μm. After that, as a result of removing unnecessary metal thin film 3 by etching, the second
, 3, a buried three-dimensional optical waveguide 5 having a width and depth of approximately 1 μm was formed. The refractive index of the three-dimensional optical waveguide 5 was 2.43.

The above-mentioned etching was performed by immersing the film for about 1 minute in a mixture of phosphoric acid, nitric acid, acetic acid, and water in a volume ratio of 16:1:2:1.

In order to confirm the waveguide characteristics of the three-dimensional optical waveguide 5, wavelength 1.
Output light from a semiconductor radar with a size of 3 μm and an output of 5 mW was focused by a lens system and coupled to a three-dimensional optical waveguide 5. the result,
Good results were obtained with a propagation loss of 0.1 dB/cm.

The optical waveguide device 6 described above was left at a high temperature of 150° C. for 500 hours and the change in propagation loss was measured. As a result, the increase in propagation loss was 0.05 dB/-Fll, which was a good result.

Example 2 A Cr mask 7 with a Y-branch optical waveguide pattern formed by the reduction projection method shown in FIG. r nide I lath layer 2 and At formed on the layer 2
The metal thin film layer 3 is brought into close contact with the metal thin film layer of the laminate as shown in FIG. Next, an electron beam with an acceleration voltage of 100 kV is uniformly scanned over the Cr mask 8. After that, the Cr[mask 7 was removed and the At metal thin film was etched. As a result, as shown in FIG.
A branched optical waveguide 8 can be formed. The Y-branch optical waveguide device 9 created in this way has a branching ratio of approximately 1:1,
Good results were obtained with a propagation loss of 0.15 dB/crR. Also, as in Example 1, as a result of being left at a high temperature of 150°C, the increase in propagation loss was 0.06 dB/m.
and obtained good results.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to form an optical waveguide that is simple, highly accurate, has low loss, and has good stability at a lower cost than conventional products. Furthermore, the method for producing an optical waveguide disclosed in the present invention will be useful in the formation of optical integrated circuits in the future, including optical multiplexers/demultiplexers for optical communications.

[Brief explanation of drawings]

FIG. 1 is a side view of an optical waveguide device showing an embodiment of the present invention, FIG. 2 is a side view showing how a three-dimensional optical waveguide is formed by an electron beam in the present invention, and FIG. 3 is an embodiment of the present invention. A perspective view of an optical waveguide element showing an example, FIGS. 4 to 6 are views showing other embodiments of the present invention, FIG. 4 is a perspective view showing a Cr mask, and FIG. 5 is a Y-branch optical waveguide. FIG. 6 is a perspective view of a Y-branch optical waveguide element. 1...Substrate, 2...Chalcogenide glass, 3...
- Metal thin film, 4... Electron beam, 5... Three-dimensional optical waveguide, 6... Optical waveguide element, 7... Mask, 8...
Y-branch optical waveguide, 9...Y-branch optical waveguide element. Agent Patent Attorney Tadashi Akimoto Jitsu 1 Figure 5

Claims (1)

[Claims] 1. Consists of a substrate, a chalcogenide glass layer formed on this substrate, and a metal thin film formed on this chalcogenide glass layer, and from the interface of the chalcogenide glass layer in contact with the metal thin film layer. An optical waveguide element characterized in that a metal diffusion layer is provided over a desired depth. 2. Form a chalcogenide glass layer on a substrate, form a metal thin film on this chalcogenide glass layer, and irradiate the metal thin film with an electron beam to form a desired shape from the interface of the chalcogenide glass layer in contact with the metal thin film layer. A method for manufacturing an optical waveguide device, comprising forming a metal diffusion layer over a depth.