JPH0862442A - Method for manufacturing glass waveguide - Google Patents

Abstract

(57) [Abstract] [Objective] Even if there is a defect on the surface of the core glass film, a low loss glass waveguide is obtained by making it uniform by a thin quartz glass film. [Structure] A core glass film 2 is formed on a quartz glass substrate 1 by an electron beam evaporation method, and in order to make the surface of the core glass film 2 uniform, a quartz glass film (a quartz glass film) is formed by a plasma CVD method or the like. ) 6 is formed. Therefore, the application of the resist film in the photolithography process becomes uniform, and unnecessary portions are removed from the quartz glass film 6 and the core glass film 2 by photolithography and reactive ion etching, so that a uniform core conductor without chipping or the like is formed. The waveguide 3 can be formed. Next, porous glass is deposited on the substrate 1, and this porous glass layer is made into a transparent glass to form a clad layer 4, thereby producing a low-loss glass waveguide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a glass waveguide, and more particularly to a method for manufacturing a glass waveguide in which unevenness of the surface of a core glass film is improved to reduce the loss of the glass waveguide. It is a thing.

[0002]

2. Description of the Related Art A conventional method for manufacturing a glass waveguide will be described with reference to FIG. First, a thick core glass film 2 is formed on a quartz glass substrate 1 forming a waveguide by an electron beam evaporation method (FIG. 3 (a)). Next, unnecessary portions of the core glass film 2 are removed by photolithography and dry etching to form the core waveguide 3 (FIG. 3 (b)). Further, a porous glass layer is deposited and formed on the core waveguide 3 of the substrate 1 by a flame deposition method, and then the porous glass layer is transparentized in an electric furnace to form a clad layer 4, and the glass waveguide is formed. (Fig. 3 (c)). After that, the quartz glass substrate 1 on which the waveguide is formed is cut into a predetermined size by a dicing device to prepare a glass waveguide element.

[0003]

However, in the glass waveguide element obtained by the above-described manufacturing process, as shown in FIG. 4, a part of the core waveguide 3 on the quartz glass substrate 1 has a chip 5. It was easy to occur.

This is because when the core glass film 2 is formed thick by the electron beam evaporation method, and also when the core glass film is formed by the flame deposition method, it adheres to the chamber of the apparatus. It is considered that excess glass or porous glass peels off and adheres to the core glass film. Due to this deposit, the surface of the core glass film 2 becomes non-uniform, and the resist in the photolithography process is not applied around the deposit. Therefore, when the core glass film 2 is dry-etched, the chip 5 is partially formed in the core waveguide 3, which causes a problem that the loss of the core waveguide increases.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a glass waveguide manufacturing method capable of manufacturing a low-loss glass waveguide even if the surface of the core glass film has a defect. To provide.

[0006]

The method of manufacturing a glass waveguide according to the present invention comprises forming a core glass film on a quartz glass substrate and forming a core glass film on the core glass film in order to make the surface of the core glass film uniform. A thin silica glass film is formed, unnecessary portions are removed from the silica glass film and the core glass film to form a core waveguide, and a clad layer is formed on the silica glass substrate on which the core waveguide is formed. It is designed to be formed.

In the present invention, the quartz glass film is
It is preferable that it is made of quartz glass or quartz glass having a refractive index equivalent to that of quartz glass, and the thickness thereof is 3 μm or less.

[0008]

[Function] Since the thin quartz glass film is formed on the core glass film, the surface of the core glass film can be smoothed and made uniform, and the resist film can be applied uniformly in the core glass film processing step. Therefore, it is possible to form a core waveguide having no defects such as chips.

When the silica glass film is made of silica glass having a film thickness of 3 μm or less or a silica glass having a refractive index equivalent to that of the silica glass film, no glass-like foreign matter is generated on the film surface and the surface of the core glass film is made uniform. In addition, the etching in the core glass film processing step can be performed in a short time, and anisotropic etching can be performed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a manufacturing process of a glass waveguide according to an embodiment of the present invention.

First, a quartz core glass film 2 having a thickness of 8 μm was formed on a quartz glass substrate 1 having a thickness of 1 mm and a diameter of 3 inches by an electron beam evaporation method (FIG. 1 (a)). On the surface of the obtained core glass film 2 on the substrate 1, glass-like foreign matters of about 2 μm were observed.

It is considered that this is because the excessive glass fine particles adhering to the inside of the chamber of the electron beam evaporator were deposited on the core glass film 2 during evaporation. Therefore, in order to make the surface of the core glass film 2 uniform, a quartz glass film 6 of quartz glass having a thickness of 2.5 μm was formed on the core glass film 2 by the plasma CVD method (FIG. 1 (b)).

Then, a WSi film having a thickness of 1 μm is formed on the quartz glass film 6 by a sputtering method, and further, 1 μm.
After applying the resist film of No. 3, unnecessary portions were removed from the quartz glass film 6 and the core glass film 2 by photolithography and reactive ion etching to form a core waveguide 3 (FIG. 1 (c)).

After that, 360 μm of porous glass was deposited on the quartz glass substrate 1, and this was made into a transparent glass in an electric furnace to form a clad layer 4 to manufacture a glass waveguide (FIG. 1 (d). )). Further, the quartz glass substrate 1 on which this waveguide is formed is cut out by a dicing device,
A glass waveguide device was produced. No defects such as chipping were found in the core waveguide 3 of the obtained glass waveguide device.

Although the quartz glass film (quartz glass film) 6 is formed by the plasma CVD method in the above embodiment, the electron beam evaporation method may be used. Even with the electron beam evaporation method, in a thin film of 3 μm or less, no glassy foreign matter is recognized on the surface of the film, and uniformization can be achieved. Similarly, the silica-based glass film may be formed by the flame deposition method. In order to obtain the same refractive index as the quartz glass substrate 1 by the flame deposition method,
A porous glass layer containing phosphorus and boron was formed and made into a transparent glass, but when the thickness of this quartz glass film was 3 μm or less, excess porous glass was small and glassy foreign matter was recognized. However, the film surface was uniform.

On the other hand, when the quartz glass film 6 is formed to a thickness of 3 μm or more, the core waveguide 3 is formed by reactive ion etching.
It took a long time to form the film, and the isotropic etching progressed, resulting in the core waveguide 3 having the shape shown in FIG. For this reason, a Mach-Cendar type optical circuit was formed as a glass waveguide element, but the intended multiplexing / demultiplexing characteristics could not be obtained.

[0017]

Since a thin quartz glass film is formed on the core glass film, the surface of the core glass film can be smoothed and made uniform, and the resist film is evenly applied in the core glass film processing step. As a result, it is possible to form a core waveguide having a predetermined shape and size without defects such as chipping, and it is possible to manufacture a low-loss glass waveguide.

When the thickness of the quartz glass film is 3 μm or less, anisotropic etching can be performed in a short time. Further, when the silica glass film is formed of the same silica glass as the silica glass substrate or silica glass having the same refractive index, the core waveguide is not adversely affected by transmission loss and the film need not be removed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state of a core waveguide after etching when a quartz glass film having a thickness of 3 μm or more is formed.

FIG. 3 is a cross-sectional view showing a manufacturing process of a conventional glass waveguide.

FIG. 4 is a plan view of a glass waveguide device obtained by a conventional method for manufacturing a glass waveguide.

[Explanation of symbols]

 1 quartz glass substrate 2 core glass film 3 core waveguide 4 clad layer 5 lack 6 quartz glass film (quartz glass film)

Claims (2)

[Claims] 1. A core glass film is formed on a quartz glass substrate, and a thin silica glass film is formed on the core glass film in order to make the surface of the core glass film uniform. And a glass waveguide, characterized in that an unnecessary portion is removed from the core glass film to form a core waveguide, and a clad layer is formed on a quartz glass substrate on which the core waveguide is formed. Method. 2. The glass conductor according to claim 1, wherein the silica glass film is made of silica glass or silica glass having a refractive index equivalent to that of silica glass, and the film thickness is 3 μm or less. Waveguide manufacturing method.