JPS62279304A - Production of optical waveguide layer - Google Patents

Abstract

PURPOSE:To improve the uniformity of a film thickness and to decrease transmission loss by preliminarily forming an Si layer on a substrate by a plasma cracking method and oxidizing said layer to form an SiO2 layer. CONSTITUTION:The substrate 2 is imposed on a sample holder 3 in a sample chamber (vacuum chamber) 1 in which the pressure is regulated. The substrate is heated by a heater 4 to a low temp. of about <=500 deg.C, for example, about 300 deg.C. On the other hand, a gas introducing hole piece 5 is connected to a high- frequency source 7. A gas contg. Si such as, for example, SiH4 is introduced through a gas introducing port 6 and the hole piece 5 into the sample chamber 1 to form Si on the substrate 2 while plasma power is kept impressed by the source 7. The Si is thereafter oxidized, by which the SiO2 is formed.

Description

[Detailed Description of the Invention] Detailed Description of the Invention [Industrial Application Field] This invention is an optical coupler that is essential for the diversification and advancement of optical communication systems and optical information processing. Economicalization and miniaturization of optical components such as containers.

The present invention relates to a method of manufacturing an optical waveguide J6 that is advantageous for stabilization.

[Conventional technology]

Conventional optical components consist of microscopic optical components such as prisms.
It was difficult to assemble the optical axis.

Therefore, in order to avoid these complicated operations by creating all four paths of light on a plane, a four-wave path method was proposed.

Examples of materials used for optical waveguides include semiconductor crystals, dielectric crystals, glass, and polymer materials. Can optical waveguides be created using these materials? To create this, a core layer and a cladding layer are formed on the substrate (which may be based on a cladding), and then the entire structure as shown in Fig. 3 is created by etching, exposure, etc., and then exposed to light. Lock it up? conduct. In addition, in Figure 3, 2
is a substrate (cladding), 9 is a cladding layer, and 8 is a core layer.

By the way, conventionally, thermal OVD method or flame direct deposition method has not been used to form the core layer and cladding layer.

The thermal aVD method, as shown in a schematic diagram in FIG.
Ct4. This is a method in which T1C1, O2, etc. are introduced, glass fine particles are combined by an oxidation reaction, and all of the synthetic glass fine particles are deposited on the substrate 2 on the holder 12. has a temperature gradient f
By adding carbon, the thermophoretic effect promotes the deposition of black glass particles. Reference numeral 14 indicates an exhaust system. In the flame direct deposition method, as shown in FIG. ．． Ttaz
4 and the like are introduced into a torch 16 for synthesizing glass fine particles having a concentric solid nozzle, and glass fine particles are synthesized by a flame hydrolysis reaction in an oxyhydrogen flame 17 formed in advance. The synthesized glass particles are deposited on the substrate 2 which is moving directly below the frame 17. In order to make the thickness of the deposited glass particles uniform, the torch 17 is moved to the turntable 15.
reciprocate in the radial direction.

[Problem that the invention seeks to solve]

However, conventional techniques such as the above-mentioned thermal C'ID method and flame direct deposition method have the disadvantage that non-uniformity of the substrate temperature during deposition causes non-uniformity of the film thickness and increases propagation loss. Ta.

The present invention aims to eliminate these two drawbacks of the prior art and provide a new method that can easily produce a low-loss optical waveguide layer.

[Friendly means of solving problems]

Instead of the conventional method of directly depositing SiO2 on a substrate, the present inventors first formed an 81 layer using a plasma decomposition method, and then oxidized this to form an 810° layer.
The present invention has been developed to solve the above-mentioned drawbacks. Namely, in the production of light on a substrate, the present invention provides a solution to the above-mentioned drawbacks. This is a method for producing an optical waveguide layer, characterized in that after forming a layer on a layer to be produced, Si in the layer is oxidized to obtain 5sio.

A particularly preferred embodiment of the present invention is the above method for producing an optical waveguide layer in which the plasma decomposition is microwave plasma decomposition. This is a good thing.

In the present invention, the Si i-containing gas is fully excited 81
In order to activate the gas, a high frequency (R?) i is applied to the gas to decompose it into a plasma state, which is so-called plasma decomposition. After that, 81 in the layer is oxidized to obtain an 8102 layer on the substrate.The reaction mechanism of the present invention at this time is as follows.

SiH → Si + 2Hz In normal plasma decomposition, 1 is considered to be a high frequency and 1μ56.
MHzf is used, but in the present invention preferably 2
．． 45 GHz microwave? A power source is applied to the ion source via a waveguide. In this specification, this is referred to as microwave plasma decomposition to distinguish it from conventional high frequency decomposition. Electrons in the ion source are imaged at high speed by this microwave, but if a magnetic field parallel to the traveling direction of the microwave is applied to the ion source at this time, the electrons are captured by the interaction between the magnetic field and the electric field caused by the microwave. Drift. When the magnetic field strength is 875 Gauss, the conditions for electron cyclotron resonance are satisfied, and the electrons are accelerated in the ion source, so the probability of ionization of neutron particles (gas) due to electron impact in the ion source is high. Become.

Examples of the Sl-containing gas used in the present invention include SiH4,! 312 horses, Si F4.5i
HC4゜SiH2CL, , 81 (including C4, etc.), and other raw material gases added to the Si, 02 layer, such as NHI, GeH4,
N2, 02, N20. B2H6, PH3, etc. may be used in addition to the Si'z gold-containing gas as the main raw material.

The flow rate of these gases is, for example, 10~
The additive raw material gas may be heated at a rate of about 50 cc/min, but there is no particular limitation. The degree of vacuum in the general reaction vessel in the present invention may be at a level that allows plasma to be generated.

The temperature of the substrate in the present invention is preferably 200 to 500.
℃ range, particularly preferably 250 to 350℃ range. Heating to this temperature can be easily controlled using conventional heating means, such as resistance heating. Furthermore, since uniform heating is possible, problems such as uneven film thickness and warping of the substrate do not occur.

Examples of the plasma conditions in the present invention include t'
The conditions were L: 145 GHz, microphone: 10-500W.

According to the present invention, when a layer containing 81 as a main component is deposited on the substrate surface under the above conditions, a good CVD rate (film deposition rate) of 100 to 500 A/min can be obtained.

A layer containing Si as a main component is deposited on the surface of the substrate, and then E3i in the layer is oxidized to form 8102. Specifically, an example! ``['Use a thermal furnace for oxidation, and use H2 as the oxidation gas.
Use O or 02.

In order to manufacture the entire optical waveguide layer by the method of the present invention, both the core and cladding layers may be formed as layers containing 1 (S>'f<main component) and then treated with an acid. A method may be adopted in which each layer is repeatedly formed and cultured on a layer containing 81 as a main component.An optical waveguide layer is obtained using a commonly known technique for pattern formation.

FIG. 1 is a schematic diagram illustrating one embodiment of the process of forming an LSI layer using a low-temperature plasma method according to the present invention. The substrate 2 is placed on the sample holder 6 inside the adjusted sample chamber (vacuum chamber) 1, and heated by the heater 4 to bring the substrate temperature to 5.
The temperature is set at a low temperature of 00°C or lower, for example, about 300°C. On the other hand, the gas introduction hole piece 5 is connected to a high frequency temporary source 7,
While applying 9 plasma power to the high side V source 7,
A gas containing Si, such as SiH4, is introduced into the sample chamber 1 through a gas depth of 6 and a gas hole piece of 5t. This
As a result, Sl is formed on the substrate 2.

〔Example〕

All 81 layers were formed according to the present invention using the apparatus shown in FIG. A quartz substrate of 100 square meters was placed in a constant sample chamber with the degree of vacuum I TorriC adjusted, and SiH425C was heated at a temperature of 300°C.
c/min was introduced to form a 15 μm thick cladding layer. Next, S i H and GeH4 were each added at 25 cc/
The mixture was introduced at a rate of 5 cc/min to form a core layer with a thickness of 4.5 μm. At this time, the plasma high frequency provisional power is 30W
Met.

Next, use a thermal furnace to heat the one-layered material obtained above at a temperature of 12
The substrate was heated to 00° C. and introduced into the entire apparatus at 20 cc/min of H2O to oxidize 81 layers, yielding the substrate shown in FIG. This t
To f2 conversion:,! The cladding layer 9 on the lll substrate 2 has a thickness of about 1μ
m, the core layer 10 has a thickness of 10 μm. After fully patterning this substrate using the conventional method, SiO2 was further deposited as a cladding layer.

The loss of the optical waveguide obtained as described above was α08 dB/α, which was extremely low loss compared to the conventional manufacturing method.

〔Effect of the invention〕

Does the method of the present invention have such effects? play.

(1) Compared to s102, the deposition rate of Sl is determined by the thermal reaction of the S1-containing gas, so the uniformity of the film thickness is 9 higher and the controllability of the film growth rate is better.

(2) Since Si is deposited by low-temperature plasma O'/D method, the temperature uniformity within the substrate surface is increased, and the film thickness is highly controlled.

(3) Formed by oxidation of 31: vaguely SiO2
Since the stoichiometry of Sl:o=1:2 is easy to control, it is possible to control the composition and the desired distribution, and the reproducibility is also extremely high.

(4) Since it is made of 5102 parts from Si, it is a high-strength stone with low loss and high uniformity.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing an embodiment of the present invention. core layer. Figure 3 is a cross-sectional view showing the -fil of the optical waveguide, Figure 4 is a cross-sectional view illustrating the entire conventional thermal CV DE, and Figure 5 is the conventional thermal CV DE. FIG.

Claims (3)

[Claims] (1) In creating an optical waveguide layer on a substrate, a Si-containing gas is plasma decomposed to form an optical waveguide layer on the substrate.
A method for manufacturing an optical waveguide layer, which comprises forming a layer containing i as a main component and then oxidizing Si in the layer to form SiO_2. (2) The method for manufacturing an optical waveguide layer according to claim (1), wherein the plasma decomposition is microwave plasma decomposition. (3) The method for manufacturing an optical waveguide layer according to claim (1) or (2), wherein the substrate is maintained at a temperature of 500° C. or lower.