JP2003287641A - Method for manufacturing laminated structure element for optical communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize the quality of products and to reduce a manufacturing cost in a method for manufacturing a laminated structure element for optical communication embedded with cores having fine patterns. <P>SOLUTION: The cores 2 made of quartz glass consisting of the fine patterns are previously formed on a quartz glass plate 1 constituting an under-clad layer. The plate 1 is placed in a lower die 11. A prescribed amount of quartz glass powder 3a is packed onto the plate 1 and the cores 2. An upper die 12 is superposed on the powder 3a and is heated up to a prescribed forming temperature. A load is exerted onto the upper and lower dies 11 and 12 from behind after the stabilization of the temperature and is held for the prescribed time. As a result, the powder 3a is changed to an over-clad layer 3 and simultaneously the plate 1 (the under-clad layer), the cores 2 and the layer 3 are joined to each other. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a laminated structure type device for optical communication in which a core having a fine pattern is sandwiched between an underclad layer and an overclad layer.

[0002]

2. Description of the Related Art A laminated structure type element for optical communication having the above structure includes, for example, a branching coupler for branching a large number of optical signals and an optical multiplexer for multiplexing optical signals.

FIG. 3 shows an outline of a 1 × 8 branch coupler. The optical signal is input from the right end surface of the figure, travels from right to left in the branch coupler, and is output from the left end surface of the figure. That is, by using this branching coupler, one optical signal is branched into eight.

The cross section of the branch coupler is as shown in FIG.
It has a laminated structure and is composed of four elements. That is, the undercladding layer 1 is laminated on the substrate 9, the core 2 on which the fine pattern forming the optical waveguide is formed is bonded onto the undercladding layer 1, and the core 2 is wrapped from above the overcladding layer 1. Layer 3 is coated.

Quartz glass or silicon is usually used for the substrate 9. The substrate 9 has a function of ensuring the mechanical strength of the element and a function of dissipating heat generated when processing an optical signal. When the substrate 9 is made of quartz glass, it can also serve as the under cladding layer 1.

In the sectional view shown in FIG. 4, the optical signal is
It propagates in the core 2 in the direction perpendicular to the paper surface. Functionally,
High transparency is required for the core. The under clad layer 1 and the over clad layer 3 have a function of shutting out light leaking from the core. Usually, the core 2 is made of quartz glass, and a small amount of germanium is added to the quartz glass in order to adjust the refractive index. On the other hand, the under clad layer 1 and the over clad layer 3 are made of undoped silica glass. Since germanium is added to the quartz glass forming the core 2, the refractive index is slightly higher than that of the underclad layer 1 and the overclad layer 3. Therefore, core 2
The optical signal that passes through does not leak to the under clad layer 1 and the over clad layer 3.

Generally, the cross section of the core 2 is 8 to 10 μm.
Each of the under clad layer 1 and the over clad layer 3 has a thickness of about several tens of μm. As the thicknesses of the under-cladding layer 1 and the over-cladding layer 3 increase, the amount of light leakage decreases and the loss also decreases.

Conventionally, the under clad layer 1 and the core 2
The overclad layer 3 and the overclad layer 3 are both formed using a process such as CVD or sputtering that is used in semiconductor manufacturing. The typical manufacturing process will be described below.

When the substrate 9 is a silicon substrate, the underclad layer 1 is deposited on the entire surface of the substrate 9. When the under clad layer 1 is formed by CVD, Si
A mixed gas of H ₄ and O ₂ is decomposed in plasma (or is decomposed by heating) and reacted in a gas phase to deposit SiO ₂ on the substrate 9.

Next, the under layer thus deposited
SiO 2 to be the core 2 on the clad 1 layer_Two5-8 layers
It is deposited with a thickness of about μm. The way to deposit is under
Similar to the clad layer 1, but with a small amount of germanium
A gas for adding a gas is added to the mixed gas. That
Such gas is usually GeH_FourIs used. core
SiO 2_TwoAfter depositing layers, a photo register on it
Stroke is deposited and patterned by photolithography.
And then using this as a mask, SiO _TwoLayers
The core 2 is formed by turning. Then under
Under clad layer from above clad layer 1 and core 2
The overclad layer 3 is deposited in the same manner as in 1.

As described above, the laminated structure type element for optical communication has been manufactured by using a method common to the semiconductor manufacturing process such as CVD.

By the way, the growth rate of the thin film by the CVD process is 0.5 μm / min to 1 μm / m at most.
It is very slow at about in, and for example, deposition of a thin film having a thickness of 50 μm requires a long time of about 50 minutes to 100 minutes.
In addition, the thin film obtained by CVD has a property that is largely different from that of bulk silica glass, which is also a problem.

In addition, the overclad layer must be deposited to fill the patterned core. In particular, such embedding is very difficult in a region where the interval between cores adjacent to each other is narrow. In addition, due to the characteristics of the CVD process, the characteristics of the thin film also differed greatly between the above-mentioned region and the region where the core-to-core spacing was wide. It is generally known that a film deposited in a region where a core is closely spaced has a small density and a refractive index correspondingly small. For example, when wet etching is performed, the film deposited in such a region is immediately dissolved. On the other hand, it is known that the film deposited in the region where the cores are spaced apart from each other is very dense and has a low etching rate.

Furthermore, the equipment used in these semiconductor manufacturing processes is very expensive. Further, in the case of CVD, a special auxiliary equipment such as an exclusion device is usually required because a gas harmful to the human body is used.

For the above reasons, the manufacturing of the above-mentioned laminated structure type element for optical communication requires a high cost, and besides, there is a problem in the uniformity of quality, which greatly affects the manufacturing yield. Was being given.

Further, Japanese Patent No. 2855092 discloses that
A method of manufacturing an optical waveguide using a process to which press molding is applied is described. FIG. 5 shows an outline of the process.

First, as shown in FIG. 5A, a groove in which a core is to be embedded later is formed on the surface of the quartz glass plate 21 by etching. Further, as shown in FIG. 5B, the glass plate 2 having a refractive index usable as a core
After stacking 2a and heating them, a pressing load is applied from above the glass plate 22a. As a result, as shown in FIG. 5C, the glass plate 22a is deformed and a part thereof is embedded in the groove.

After that, as shown in FIG. 5D, the core 22 is formed by removing the excess portion of the glass plate 22a left outside the groove. Next, as shown in FIG. 5 (e), a quartz glass plate 23 of the same kind as the quartz glass plate 21 is placed on the quartz glass plate 21 and the core 22 embedded in the groove and fused, Complete the optical waveguide.

This method is used when the core is formed (see FIG.
(C)) Since the glass plate 22a is heated and deformed by applying a pressing load, it was very difficult to embed the glass plate 22a in the groove. As described in the above-mentioned patent publications, the quartz glass plate 2 constituting the cladding layer 2
If the glass plates 22a constituting the cores 1 and 23 and the core 22 are made of different materials and have different softening points, there is no problem. However, when the clad layer and the core have almost the same softening point, a large pressing force is required to flow the glass, and as a result, the underclad is deformed when the core is formed. There was a problem to say.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems in the conventional method for manufacturing a laminated structure type device for optical communication as described above, and an object of the present invention is to provide a fine pattern. It is an object of the present invention to provide a manufacturing method capable of stabilizing the quality of a laminated structure type element for optical communication in which a core having the above is embedded and reducing the manufacturing cost thereof.

[0021]

A method for manufacturing a laminated structure type device for optical communication according to the present invention is for optical communication in which a core having a fine pattern is sandwiched between an underclad layer and an overclad layer. In the method for manufacturing a laminated structure type device, a core is previously formed on the upper surface, and a plate-shaped member that constitutes an underclad layer is placed in a lower mold, and after the glass powder is filled on the plate-shaped member and the core. , The upper mold is overlaid thereon, the lower mold, the plate-shaped member, the core, the glass powder and the upper mold are heated, and then a press load is applied between the upper mold and the lower mold, whereby The glass powder itself is fused to form an overclad layer, and at the same time, the plate-shaped member, the core and the overclad layer are bonded to each other.

According to the manufacturing method of the present invention, the laminated structure type element is manufactured by press-molding the glass powder under heating, so that the manufacturing process is simple, the productivity is high, and the conventional manufacturing method is used. The manufacturing cost can be reduced as compared with. The particle size of the glass powder used is determined by the size of the embedded fine pattern.

In the case of manufacturing a laminated structure type element in which an optical waveguide is composed of a core, such as a branch coupler or an optical multiplexer, it is preferable to use a quartz glass plate as the plate member. Then, a fine pattern made of quartz glass is used as the core, and quartz glass powder is used as the glass powder.

As a modified version of the above method, if a groove in which a core will be embedded later is formed in advance on the surface of the plate-like member constituting the underclad layer, the core portion can be made of glass powder.

In this case, the method of manufacturing a laminated structure type element for optical communication according to the present invention is a laminated structure type for optical communication in which a core having a fine pattern is sandwiched between an underclad layer and an overclad layer. In the device manufacturing method, a groove in which a core is to be embedded later is formed on the surface of a plate-shaped member forming the under-cladding layer, the plate-shaped member is placed in a lower mold, and glass powder is filled on the plate-shaped member. , The upper mold is overlaid thereon, the lower mold, the plate-shaped member, the glass powder and the upper mold are heated, and then a press load is applied between the upper mold and the lower mold to obtain the glass powder. By fusing, to form a glass layer on the plate-like member, from the plate-like member, by removing the glass layer leaving a portion in the groove, in the groove Forming a core, the plate-shaped member and the front After the material constituting the overclad layer is put on the core, the upper mold is overlaid thereon, and after heating the lower mold, the plate member, the core, the material and the upper mold, the upper mold A pressing load is applied between the mold and the lower mold, whereby the overclad layer is bonded onto the plate-shaped member and the core.

In the case of manufacturing a laminated structure type element in which an optical waveguide is composed of a core, it is preferable to use a quartz glass plate as the plate-shaped member and the material, and use quartz glass as the glass powder. Powder is used.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Example 1) FIG. 1 shows an example of a method for manufacturing a laminated structure type element for optical communication according to the present invention. Here, a case of manufacturing a branch coupler will be described as an example. In the figure, 1 is a quartz glass plate (plate member, underclad layer), 2 is a core, 3 is an overclad layer, 1
1 represents a lower mold and 12 represents an upper mold.

First, a silica glass core 2 having a fine pattern that constitutes an optical waveguide is provided on the upper surface of a quartz glass plate 1 that constitutes an underclad layer. The core 2 is formed by photolithography or the like as in the conventional case.
However, the layers forming the core 2 are formed not by CVD or sputtering, but by press molding using quartz glass powder or a plate as in the case of forming the over cladding layer 3 described later, and then by etching the core 2 May be formed.

Next, as shown in FIG. 1A, the lower mold 11
The quartz glass plate 1 is placed in the inside.

Next, as shown in FIG. 1B, a predetermined amount of silica glass powder 3a is filled on the silica glass plate 1 and the core 2. In this example, the particle size of the quartz glass powder 3a was 2 μm. The particle diameter of the quartz glass powder 3a is set based on the mutual spacing of the embedded cores.
The amount of the quartz glass powder 3a is set according to the thickness of the over cladding layer 3 formed therefrom. In addition, although the cross-sectional size of the core is exaggeratedly drawn large in this figure, it is actually a fraction of the thickness of the quartz glass plate 1 (undercladding layer).

Next, as shown in FIG. 1 (c), the upper mold 12 is placed on the quartz glass powder 3a and heated to a predetermined molding temperature by using an infrared lamp 13. In this example, 14
Heated to 00 ° C.

After the respective molding materials 1, 2, 3a are stabilized at the above temperature, as shown in FIG. 1 (d), the upper and lower molds 11, 1 are formed.
A press load is applied from the back of No. 2 and held for a predetermined time. As a result, the silica glass powder 3a is fused to form the over cladding layer 3, and at the same time, the silica glass plate 1 (under cladding layer), the core 2 and the over cladding layer 3 are bonded to each other. In this example, the temperature: 14
It was held at 00 ° C. and a load of 8 kN for 10 minutes.

This process is important, and the degree of bonding between the silica glass powders changes depending on the length of the holding time. The longer the length, the stronger the degree of bonding, and the smoother, transparent film is obtained. On the contrary, if the length is short, the film becomes opaque and discontinuous. Further, the above holding time differs depending on whether the material used is synthetic quartz or fused quartz. Generally, synthetic quartz has a lower softening point, so that the holding time can be shortened.

It is also important to keep the press load constant in this process. The thickness (dimension e in FIG. 1C) gradually decreases as the quartz glass powder enters the gap between the powders at high temperature. At this time, unless a constant press load is applied, the film quality in the over cladding layer 3 becomes non-uniform, which causes variations in the refractive index and the like.

After completion of the press molding process, the upper and lower molds 11,
12 and the molded product are cooled, and when the temperature reaches a predetermined temperature, the mold is opened and the molded product is collected.

When a branch coupler was manufactured under the above conditions, smooth and transparent quartz glass could be obtained as the overclad layer 3. The thickness (dimension f in FIG. 1D) was 50 μm.

(Example 2) FIG. 2 shows another example of a method for manufacturing a laminated structure type element for optical communication according to the present invention. Here, too, the case of manufacturing a branch coupler will be described as an example.

In advance, a groove in which a core will be embedded later is formed on the surface of the quartz glass plate 1 constituting the underclad layer by etching (or press molding with a mold).

As shown in FIG. 2 (a), the above-mentioned quartz glass plate 1 is placed in the lower mold 11, and a predetermined amount of quartz glass powder 2c is placed thereon as shown in FIG. 2 (b). Fill.
Next, the upper mold 12 is placed on the quartz glass powder 2c and heated to a predetermined molding temperature. After the upper and lower molds 11 and 12 and the molding materials 1 and 2c are stabilized at the above temperature,
As shown in (c), a press load is applied from behind the upper and lower molds 11 and 12 and the mold is held for a predetermined time. by this,
As shown in FIG. 2D, the quartz glass powder 2c is fused and converted into the quartz glass 2, and a part thereof is embedded in the groove.

Next, the core is formed by removing the surplus portion of the quartz glass 2 left outside the groove.
Then, as shown in FIG. 2 (e), a quartz glass plate 5 (material) (or quartz glass powder (material)) is placed on the quartz glass plate 1 and the core 2 embedded in the groove. Place and fuse to complete the branch coupler.

According to this method, the quartz glass plate 1 can be applied with a smaller press load as compared with the conventional method shown in FIG.
The core 2 can be mounted in the groove on the surface of the core.

[0042]

According to the manufacturing method of the present invention, since the laminated structure type element for optical communication is manufactured by press molding the glass powder under heating, the manufacturing process is simple and the productivity is high. This is high, and the manufacturing cost can be reduced as compared with the conventional manufacturing method.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of a method for manufacturing a branch coupler based on the method of the present invention, and FIGS. 1A to 1D are diagrams showing each step.

FIG. 2 is a diagram for explaining another example of a method for manufacturing a branch coupler based on the method of the present invention, and FIGS. 2 (a) to 2 (e) are diagrams showing each step.

FIG. 3 is a plan view showing the structure of a branch coupler for optical communication.

FIG. 4 is a sectional view showing the structure of a branch coupler for optical communication.

FIG. 5 is a diagram illustrating an example of a conventional method of manufacturing an optical waveguide, and (a) to (e) are diagrams showing respective steps.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Quartz glass plate (under clad layer), 2 ... Core, 2c ... Quartz glass powder, 3 ... Over clad layer, 3a ... Quartz glass powder, 5 ... Quartz glass plate Or quartz glass powder (material: overcladding layer), 9 ... substrate, 11 ... lower mold, 12 ... upper mold, 13 ... infrared lamp, 21 ... quartz glass plate, 22 ... -Core, 22a ... glass plate, 23 ... quartz glass plate.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shusaku Matsumura             2068 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd.             In the company F term (reference) 2H047 KA03 KA12 LA12 PA26 QA04                 4G014 AH00

Claims (4)

[Claims] 1. A method for manufacturing a laminated structure type device for optical communication, wherein a core having a fine pattern is sandwiched between an underclad layer and an overclad layer, wherein a core is previously formed on an upper surface of the underclad layer. Placing a plate-shaped member constituting a lower mold, filling the plate-shaped member and the core with glass powder, and then stacking an upper mold thereon, the lower mold, the plate-shaped member, the core After heating the glass powder and the upper mold, a pressing load is applied between the upper mold and the lower mold, whereby the glass powder itself is fused to form an overclad layer, and at the same time, the plate. A method for manufacturing a laminated structure type element for optical communication, comprising bonding a sheet-shaped member, the core, and the overclad layer to each other. 2. The plate member is a plate made of quartz glass, the core is a fine pattern made of quartz glass, and the glass powder is powder of quartz glass,
The method for manufacturing a laminated structure type element for optical communication according to claim 1, wherein an optical waveguide is constituted by the core. 3. A method for manufacturing a laminated structure type device for optical communication in which a core having a fine pattern is sandwiched between an underclad layer and an overclad layer, the surface of a plate-shaped member constituting the underclad layer. Then, a groove in which the core is embedded later is formed, the plate-shaped member is placed in a lower mold, glass powder is filled on the groove, and then the upper mold is stacked thereon, the lower mold, the plate-shaped member. After heating the glass powder and the upper mold, a press load is applied between the upper mold and the lower mold to fuse the glass powder to form a glass layer on the plate-shaped member. Then, a core is formed in the groove by removing the glass layer from the top of the plate-shaped member while leaving the portion in the groove, and the core is formed on the plate-shaped member and the core. Injecting the materials that make up the clad layer After that, the upper mold is overlaid thereon, the lower mold, the plate-shaped member, the core, the material and the upper mold are heated, and then a press load is applied between the upper mold and the lower mold, A method for manufacturing a laminated structure type element for optical communication, comprising: bonding an overclad layer on the plate-shaped member and the core by the method. 4. The plate member and the material are plates made of quartz glass, the glass powder is powder of quartz glass, and the core constitutes an optical waveguide. A method for manufacturing a laminated structure type device for optical communication as described above.