JP3204437B2 - Fabrication method of mounting substrate for hybrid optical integration - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention applies to a method for manufacturing a hybrid optical integrated for mounting board, in particular, in the hybrid optical integrated circuits used in optical communication and optical information processing, in the production of mounting board serving as its platform And effective technology.

[0002]

2. Description of the Related Art With the advancement of optical communication and optical information processing in recent years, the realization of a hybrid optical integrated circuit in which optical elements made of different materials are integrated on the same substrate is expected. In particular, the mounting substrate for hybrid optical integration using silicon (Si) as the material of the substrate and glass as the material of the optical waveguide has an optical bench function utilizing the high workability of Si and an excellent waveguide of the glass optical waveguide. It is very promising as having both wave characteristics.

FIG. 13 shows a quartz-based optical waveguide 2 ′ in a concave portion on a Si substrate 1 ′ having irregularities, which has been studied recently.
Is referred to as “an optical waveguide substrate with a terrace” in which an optical element mounting portion is formed on a convex terrace portion 4 ′ (Yamada et al., 1993 IEICE Spring Conference C-234, “S for Hybrid Optical Integration”
Formation of iO ₂ / Si Substrate ”) in which a semiconductor laser diode (LD) 3 ′ is integrated. An electric wiring 9 ′ is formed on the convex terrace 4 ′ of the Si substrate 1 ′, and a quartz optical waveguide 2 ′ is formed from the upper surface of the electric wiring 9 ′.
Is set to be equal to the height from the element surface of the LD 3 'to the active layer.
By simply mounting the 3 ′ on the convex Si terrace portion 4 ′ of the Si substrate 1 ′, alignment of the optical axis in height can be realized without adjustment.
At the same time, the convex terrace portion 4 'also functions as a heat sink for the LD 3'. Thus, the hybrid integration of the optical waveguide and the optical element can be easily realized by using the “optical waveguide substrate with a terrace”.

FIG. 14 is a sectional view of each part in each step for explaining a method of manufacturing such a mounting board.
First, as shown in FIG. 14A, a convex Si terrace portion 4 'is formed on a portion of the Si substrate 1' where an optical element mounting portion is to be formed. Next, as shown in FIG. 14B, an under cladding layer 5 ′ is deposited so as to completely bury the convex Si terrace portion 4 ′, and then as shown in FIG. In order to form a reference surface for positioning the optical element (LD3 ') in the height direction, the substrate surface is flattened and polished to expose the terrace surface. And FIG.
As shown in FIG. 2D, when the optical element is mounted, the buffer layer 6 'for adjusting the height and the core so that the center of the core 7' of the quartz optical waveguide 2 'and that of the optical element (LD3') coincide with each other. 7 '
Are sequentially deposited. Subsequently, as shown in FIG. 14E, the patterning of the core 7 'and the over cladding layer 8'
Is deposited to produce a quartz optical waveguide 2 ′. Finally, as shown in FIG. 4 (f), the glass removal of the mounting portion and the formation of the electrical wiring 9 'are performed to produce the optical element mounting portion, and the production of the mounting substrate is completed.

[0005]

The present inventor has found the following problems as a result of studying the conventional terraced optical waveguide substrate.

In the structure of the conventional optical waveguide substrate having a terrace, the inclined side wall 40 'of the convex Si terrace portion 4' is provided.
The quartz optical waveguide 4 'also exists on the upper side, but this causes a problem that stress concentrates on the interface between the Si recess and the inclined side wall 40'. In general, when stress concentration occurs in a specific portion of the Si substrate 1 ', there is a concern that the mechanical strength of that portion is deteriorated.

[0007] In the above-described method of manufacturing a mounting board, a polishing step is used, but this step causes some problems. First, the surface of the substrate is deteriorated by polishing, which leads to deterioration of the waveguide characteristics such as an increase in the waveguide loss in the quartz optical waveguide 2 ′, and a convex Si in the optical element mounting portion. There is a problem that the workability of the surface of the terrace portion 4 'is deteriorated and the optical bench function is impaired.

[0008] Second, in the case of Si and glass materials, particularly, silica glass, due to the difference in their thermal expansion coefficients,
When a glass film having a thickness of several tens of μm is formed on the Si substrate 1 ′, the Si substrate 1 ′ is largely warped, the thickness distribution of the glass layer to be left is uniform, and the convex terrace portion 4 ′ is formed. In order to uniformly polish two different materials in order to eliminate a surface step at a boundary, a complicated process such as flattening is required. Further, when the polishing becomes non-uniform, the stress distribution in the quartz optical waveguide 2 ′ becomes non-uniform, and there is a problem that the waveguide characteristics may be deteriorated.

Third, the reference plane for alignment of the optical element is always the upper surface of the under cladding layer 5 'and the upper surface of the convex Si terrace 4', and the structure of the mounted optical element (from the center of the active layer). It is necessary to adjust the height such as the formation of the buffer layer 6 'according to the distance to the upper electrode surface), and
For mounting a plurality of elements having different structures, there is a problem that it is necessary to form a plurality of buffer layers 6 'in a plurality of optical waveguide manufacturing steps.

Fourth, when polishing is performed, the polishing amount is set to 1
It is very difficult to control with an accuracy within μm,
It is impossible to previously form a structure requiring high precision, such as a guide groove for an optical fiber, a marker for positioning an optical element, or a marker for aligning a photomask.

An object of the present invention is to provide a high performance hybrid optical
Fabrication of integrated mounting substrate in a simple process without using a polishing process
It is an object of the present invention to provide a method for manufacturing a mounting substrate for optical integration, which can be performed .

[0012]

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0014]

The outline of a typical invention among the inventions disclosed in the present application will be briefly described as follows.

That is, the present invention provides a substrate having a concave portion and a convex portion.
An under cladding layer, a core pattern,
And providing an optical waveguide consisting of an over cladding layer,
The region including the convex portion is defined as an optical element mounting portion, and
Of mounting substrate for hybrid optical integration with electrical wiring
Manufacturing method, wherein the substrate is recessed by wet etching.
And a substrate processing step of forming a convex portion having an inclined side wall
And an under clad of a predetermined thickness on the entire surface of the substrate
After forming the layer, a predetermined shape is formed on the under cladding layer.
Core pattern is formed, and then the entire substrate is
Forming an optical waveguide for forming a bar clad layer;
The convex portion having the inclined side wall of the plate and the concave portion near the convex portion are provided.
Removing the optical waveguide to expose the surface
And an electric wiring pattern for forming an electric wiring pattern on the exposure
And a forming step .

In a preferred embodiment of the present invention, the above group
The plate is a silicon substrate .

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

According to the above-mentioned means, the optical waveguide is removed from the convex and concave portions of the substrate, and the optical waveguide is arranged so as not to contact the convex portion of the substrate. The occurrence of stress concentration at the bottom of the substrate protrusion can be suppressed.

Further, by providing optical element mounting portions on a plurality of types of substrate protrusions having different heights, a plurality of types of optical elements having different structures can be mounted on the same optical mounting substrate.

Further, according to the manufacturing method of the present invention, a convex portion having a height set from the structure of the optical waveguide, the optical element and the mounting portion thereof is formed in advance at the mounting portion forming position, and is formed in the height direction. Since the optical element is mounted as a reference plane for alignment, the polishing step for the preparation of the reference plane in the conventional method is unnecessary, and various problems such as poor waveguide characteristics caused by this are eliminated. Can be solved.

According to the manufacturing method of the present invention, when removing the unnecessary portion of the optical waveguide for forming the optical element mounting portion, the thickness of the optical waveguide existing on the convex portion and the concave portion of the substrate is the same. For this reason, when the removal of the optical waveguide on the substrate convex portion is completed, the removal of the optical waveguide on the surface of the substrate concave portion can be completed at the same time. This facilitates realization of the above-described mounting substrate for hybrid optical integration of the present invention.

Further, in the present invention, since it is not necessary to polish the substrate, there is no deformation of the substrate shape due to the substrate polishing in a later step. For this reason, by forming an optical waveguide after forming a plurality of types of substrate projections having different steps in advance, it becomes possible to mount a plurality of types of optical elements having different configurations.

For the same reason, the structure formed on the substrate with high precision in the first step can be used as it is, and the guide groove and various markers can be formed.
In particular, when Si is used as the material of the substrate, various functions can be added to the mounting substrate by making full use of current excellent micromachine technology. For example, guide grooves (V grooves) for optical fibers and markers for alignment of optical elements can be formed.

Further, since it is not necessary to polish the substrate, an organic polymer material can be used as the material of the optical waveguide. Thus, an economical mounting substrate can be manufactured.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

In all the drawings for describing the embodiments, parts having identical functions are given same symbols and their repeated explanation is omitted.

(Embodiment 1) FIG. 1 is a view showing a schematic configuration of a mounting substrate for hybrid optical integration according to Embodiment 1 of the present invention, wherein 1 is a substrate, 2 is an optical waveguide, 3 is an optical element, and 3a is The under cladding layer of the optical element 3 and the core 3b of the optical element 3
c is an over cladding layer of the optical element 3, 4 is a convex portion (terrace portion) having an optical element mounting portion, 5 is an under cladding layer,
7 is a core, 8 is an over cladding layer, and 40 is an inclined side wall.

As shown in FIG. 1, the mounting substrate for hybrid optical integration of the first embodiment is, for example,
The optical waveguide 2 uses, for example, a quartz-based waveguide, and the optical element 3 uses, for example, a semiconductor laser diode (LD). The optical waveguide 2
Is formed in a concave region of the substrate 1 and includes an under cladding layer 5, a core pattern 7, and an over cladding layer 8. The optical waveguide 2 is made of, for example, quartz glass. That is, the under cladding layer 5, the core pattern 7, and the over cladding layer 8 are each made of quartz glass.

On the upper surface of the convex portion (Si convex portion) 4, a region for an optical element mounting portion is formed. The optical waveguides 2 made of silica glass are all removed from above the convex portions and concave portions of the substrate, and both the convex portions (Si convex portions) 4 and the concave portions (Si concave portions) have an exposed structure. .

The upper surface of the projection 4 serves as a reference plane for alignment in the height direction when the optical element is mounted, and the height of the projection 4 depends on the optical waveguide 2 and each layer in the element mounting portion on the projection 4. And the structure of the optical element 3. In the optical waveguide portion, the thickness du of the under cladding layer 5 was reduced from 20 to 30 μm in a normal case to 10 μm so as not to affect the waveguide loss in order to increase the accuracy in the height direction.

The thickness dc of the core pattern layer 7 is set to 6 μm.
m, its width was set to 6 μm, the relative refractive index difference △ was set to 0.75%, and the thickness of the over cladding layer 8 was set to 20 μm. Therefore, the height (du + dc / 2) from the bottom surface of the under cladding layer 5 to the center of the core 7 of the optical waveguide 2 is 1
3 μm.

On the other hand, in the optical element mounting portion, the height L (distance between the center of the active layer of the optical element 3 and the upper electrode surface) L of the core 3b of the optical element (LD) 3 is 3 μm, The electrical wiring 9 formed on the mounting portion is composed of an insulating SiO ₂ film 9a, a conductive pattern 9b, and a solder film 9c. The thicknesses are set to 1 μm, 1 μm, and 3 μm, respectively. The height g from the surface of the mounting portion to the surface of the electric wiring 9 is 5 μm. The height (L + g) from the center of the core of the optical element (LD) 3 to the upper surface of the projection 4 when the optical element (LD) 3 is mounted upside down is 8 μm.
Therefore, the difference between the heights of the two ｛(du + dc / 2) −
From (L + g)｝, the height h of the projection 4 is set to 5 μm. With such a setting, in FIG. 1, the convex portion 4 functions as a height reference plane.

The most characteristic feature of the first embodiment is, as described above, that the entire optical waveguide layer is removed from the optical element mounting portion on the convex portion 4. In particular, in the vicinity of the convex portion 4, the quartz optical waveguide 2 is also provided on the inclined side wall 40 on the side surface of the convex portion 4.
Is not formed. Such a structure is shown in FIG.
, Ie, a structure in which the optical waveguide 2 ′ is formed on the inclined side wall 40 of the convex terrace portion 4 ′.
There is an effect that stress concentration on the substrate 1 and the optical waveguide 2 can be prevented.

That is, if a quartz optical waveguide having a different coefficient of thermal expansion is formed on the inclined surface, a stress in a direction different from that of the other flat region is generated in this region. In this case, stress concentration tends to occur on the substrate 1. With the structure of the first embodiment, this stress concentration can be prevented.

FIG. 2 is a cross-sectional view of each part in each step for explaining a method of manufacturing the hybrid optical integrated mounting substrate of the first embodiment (FIG. 1). FIG. Sectional views, (b) and (c) are cross-sectional views during the optical waveguide forming step, (d) are cross-sectional views during the optical element mounting section forming step, and (e) are cross-sectional views during the electrical wiring forming step. FIG. FIG. 3 is an enlarged view of the electric wiring section in FIG.

As shown in FIG. 2A, the mounting substrate for hybrid optical integration according to the first embodiment is manufactured by forming the convex portion 4 having the optical element mounting portion on the Si substrate 1. The convex portion 4 having the optical element mounting portion is formed by anisotropic etching of a potassium hydroxide (KOH) aqueous solution using a mask 10 made of gold (Au). The height h of the projection 4 is 5 μm
Set to.

Next, as shown in FIG. 5B, the under cladding layer 5 and the core layer 7 were continuously deposited by a flame deposition method (FHD method), and a fluorine-based gas was used. The core layer 7 is patterned by reactive ion etching (RIE). After that, as shown in FIG. 1C, the optical waveguide 2 is formed by depositing the over cladding layer 8. In this optical waveguide forming step, the thickness du of the under cladding layer 5 is 10 μm, and the thickness dc of the core layer is 6 μm.
m, the width is 6 μm, and the thickness of the over cladding layer 8 is 2
It was set to 0 μm.

In the step of forming the optical waveguide, the surface of the optical waveguide 2 is slightly uneven due to the step of the convex portion 4. If this level is severe, the pattern accuracy will be significantly deteriorated in the core patterning step shown in FIG.

However, as in the first embodiment, the thickness of the under cladding layer 5 is made as small as possible, and the height of the projection 4 having the optical element mounting portion is set low accordingly. As a result, this problem has been solved, and the conventional substrate polishing is no longer required.

Next, as shown in FIG. 4D, the optical waveguide (quartz optical waveguide) 2 is etched by reactive ion etching (RIE) to expose the surface of the convex portion 4 and the concave portion. Thereafter, as shown in FIG. 3E and FIG. 3, an electric wiring 9 composed of an insulating layer 9a having a thickness of 1 μm, a conductor pattern 9b having a thickness of 1 μm, and a solder film 9c having a thickness of 3 μm was formed on the surface of the convex portion 4 and the concave portion. . Therefore, the height g from the surface of the projection 4 having the optical element mounting portion to the surface of the electric wiring 9 is 5
μm.

As a result, the height from the surface of the electric wiring 9 to the center of the core 7 of the optical waveguide (quartz optical waveguide) 2 is 3 μm according to the following equation (Equation 2).

[0050]

(Du + dc / 2)-(h + g) = 3 Therefore, as shown in FIG. 3, an optical element (LD) in which the height L from the element surface to the active layer is set to 3 μm on the convex portion 4 ) 3, the optical waveguide (quartz optical waveguide)
2 is completed without any alignment in the height direction.

In the first embodiment, the convex portions 4 are formed by wet etching using KOH and the waveguide is formed by the FHD method. However, the present invention is not limited to this method. RIE using a fluorine-based gas may be used for the unevenness processing of the substrate 1, and a chemical vapor deposition method (CVD method) may be used for manufacturing the optical waveguide. In this case, the shape of the convex portion of the Si substrate is
It does not have the inclined side wall 40 as in the first embodiment, but has a vertical side wall. Further, Si is used as the material of the substrate 1 and quartz glass is used as the glass material for the optical waveguide. However, there is no particular limitation on these materials. It is also possible to use various dielectric materials such as multi-component glass and polymer thin film as the material of the optical waveguide 2 on the alumina substrate on which the optical waveguide 4 is formed.

(Embodiment 2) FIG. 4 is a view showing a schematic configuration of an embodiment 2 of a mounting substrate for hybrid optical integration according to the present invention. As shown in FIG. 4, the mounting substrate for hybrid optical integration of the second embodiment uses Si as the material of the substrate 1 and manufactures the mounting substrate using the quartz-based waveguide as the optical waveguide 2. In correspondence with hybrid optical integration of a plurality of optical elements having different core heights, a plurality of projections 4 having different heights are provided.
In the second embodiment, two elements of a semiconductor laser diode (LD) and a photodiode (PD) 11 are integrated as the plurality of optical elements 3.

FIG. 5 is a cross-sectional view of each part in each step for explaining the method of manufacturing the hybrid optical integrated mounting substrate of the second embodiment. As shown in FIG. 5, the manufacturing method of the mounting substrate for hybrid optical integration according to the second embodiment is as follows.
On the substrate 1, projections 4a and 4b having different heights corresponding to the LD (optical element) 3 and the PD 11 are formed. Here, the structures of the optical waveguide 2 and the LD 3 are the same as those in the first embodiment. If the height of the core 3a of the PD 11 is set to 5 μm, the heights of the protrusions 4a and 4b correspond to the LD 3 and the PD 11. They are 5 μm and 3 μm, respectively. The plurality of projections 4a,
The formation of 4b is performed from the one with the large convex part height,
First, as shown in FIG. 3A, a mask 10a made of gold (Au) is formed on a portion where the LD convex portion 4a is to be formed, and etching is performed by 2 μm, which is the difference in height between the two convex portions. next,
(B) As shown in the figure, after a mask 10b made of gold (Au) is also formed on a portion where the PD convex portion 4b is to be formed, 3
Etching of μm is performed, and both convex portions 4a and 4b are set to a predetermined height. Thereafter, a mounting substrate is manufactured in the same process as in the first embodiment (FIG. 5C).

In the second embodiment, two convex portions 4a,
4b is shown, but it is possible to mount a plurality of optical elements 3 without adjusting the height in a later step as long as a protrusion having a plurality of heights is formed first. Yes, this structure can be easily manufactured by applying existing micromachine technology.

(Embodiment 3) FIGS. 6A and 6B are diagrams showing a schematic configuration of an embodiment 3 of a mounting substrate for hybrid optical integration according to the present invention, wherein FIG. 6A is a plan view seen from above, and FIG. Is a cross-sectional view taken along line CC in FIG. 7A, and FIG.
It is sectional drawing cut | disconnected by the B line.

As shown in FIG. 6, the mounting substrate for hybrid optical integration according to the third embodiment uses Si as a material of the substrate 1,
This is an example in which an optical fiber guide groove 13 for guiding the optical fiber 12 is formed on the convex portion 4 when manufacturing a mounting substrate using a silica-based waveguide as the optical waveguide 2.

FIG. 7 is a cross-sectional view of each part in each step for explaining a method of manufacturing the hybrid optical integrated mounting substrate of the third embodiment. First, as shown in FIG. 7A, the method of manufacturing the mounting substrate for hybrid optical integration according to the third embodiment includes the steps of forming the projection having the optical element mounting portion and the guide groove 13 for the optical fiber. Covering with a mask 10 made of gold (Au), a projection 4 having a height of 10 μm is formed.

Next, as shown in FIG. 7 (b), the V-shape as shown in FIG. 6 (b) is formed on the covered convex portion 4 by anisotropic etching of KOH. An optical fiber guide groove 13 is formed. Here, the distance from the upper surface of the projection 4 to the center of the core 7 of the optical waveguide 2 is 8 μm, and the outer diameter of the optical fiber 12 is 125 μm.
An anisotropic etching is performed by opening a window having a width of 56 μm.

Subsequently, as shown in FIG. 7C, the steps from the formation of the optical waveguide 2 to the formation of the electric wiring 9 are performed by the same steps as those in the first embodiment, and finally, as shown in FIG. (D) As shown in the figure, an optical fiber connection end face 14 of the optical waveguide 2 is formed by a dicing saw.

In the third embodiment, an optical fiber guide groove 13 is formed on the substrate 1 in advance, and then the same glass film is deposited and etched as in the first embodiment. When etching is performed using a base gas, S is selected due to a large etching selectivity between Si and glass.
Since i acts as an etching stop surface, a highly accurate guide groove can be produced without deformation of the shape, and connection with an excess loss of 0.3 dB or less was realized in the third embodiment as well.

(Embodiment 4) FIGS. 8A and 8B are diagrams showing a schematic configuration of an embodiment 4 of a mounting substrate for hybrid optical integration according to the present invention, wherein FIG. 8A is an integrated structure diagram, and FIG. (C) is a diagram showing an alignment marker formed on the convex portion.

In the mounting substrate for hybrid optical integration according to the fourth embodiment shown in FIG. 8, when an optical device mounting portion is used for manufacturing a mounting substrate using Si as the material of the substrate 1 and using a quartz-based waveguide as the optical waveguide 2, This is an example in which hybrid optical integration is performed by a passive alignment method by combining an optical element alignment marker 15 formed on the surface of the convex portion 4 and an electrode pattern 16 formed on the LD 3.

FIG. 9 is a cross-sectional view showing a cross section of each part in each step for explaining the method of manufacturing the mounting substrate for hybrid optical integration according to the fourth embodiment. In the method of manufacturing the mounting substrate for hybrid optical integration according to the fourth embodiment, first, the alignment marker 15 is formed on the Si substrate 1 as shown in FIG. Next, as shown in FIG. 9B, the convex portion 4 is formed at the position where the optical element is mounted while the portion where the marker is formed is covered with a mask 10 made of gold (Au). Thereafter, as shown in FIG. 9C, a mounting substrate is manufactured by the same steps as in the first embodiment.

In the fourth embodiment, the first substrate 1
Since the alignment marker 15 is formed at the flat stage, the processing can be performed with high accuracy in both dimensions and shape, and no deformation is observed in the subsequent process as in the third embodiment. Positioning of the optical element 3 and the mounting substrate in microns was achieved.

(Embodiment 5) FIGS. 10A and 10B are diagrams showing a schematic configuration of an embodiment 5 of a mounting substrate for hybrid optical integration according to the present invention, wherein FIG. 10A is a diagram showing an integrated structure, and FIG. FIG. 3 is a view showing an electrode structure.

In the mounting substrate for hybrid optical integration according to the fifth embodiment shown in FIG. 10, when the mounting substrate using Si as the material of the substrate 1 and the quartz-based waveguide as the optical waveguide 2 is manufactured, the optical element mounting portion is used. A dielectric layer 17 near the protrusion 4
And forming the electric wiring 9 thereon,
This is an example in which high-frequency electrical characteristics are improved.

FIG. 11 is a cross-sectional view of each part in each step for explaining the method of manufacturing the hybrid optical integrated mounting substrate of the fifth embodiment. As shown in FIG. 11A, the manufacturing method of the hybrid optical integration mounting substrate of the fifth embodiment is the same as that of the first embodiment up to the removal of the glass film of the optical element mounting portion. Next, as shown in FIG. 11B, a polyimide layer 18 having a thickness of 20 μm is formed on the side of the Si convex portion of the optical element mounting portion 4, and as shown in FIG. After forming the coplanar electric wiring 9 on the polyimide layer 18, the LD 3a was finally mounted. As a result, the high-frequency characteristics are greatly improved as compared with the case where the electric wiring 9 is formed directly on the Si substrate 1 via a thin insulating film, and 1 gigabit / second (Gbit /
s) Driving in the above is possible.

(Embodiment 6) FIG. 12 is a view showing a schematic configuration of an embodiment 6 of a mounting substrate for hybrid optical integration according to the present invention, wherein Si is used as a material of a substrate 1 and a polymer is used as an optical waveguide 2. This is an example in which the hybrid optical integration mounting substrate of the sixth embodiment using the waveguide 19 is manufactured, and the hybrid optical integration of the LD 3 is performed. Here, the manufacturing process of the substrate according to the present embodiment includes the FHD
A polymer waveguide film is formed by a spin coating method instead of the deposition of a silica-based glass by the RIE method, and is manufactured in a similar process by changing a gas used for the RIE method from a fluorine-based gas to oxygen.

In the conventional manufacturing method using polishing,
Although it was difficult to use an organic material as the material of the optical waveguide 2, in the present invention, since the substrate is not polished, it is possible to use an organic material as the material of the optical waveguide 2. For film formation, a spin coating method can be used. As a result, it is possible to greatly improve economical efficiency in manufacturing a mounting substrate.

Although the present invention has been specifically described based on the above embodiments, the present invention is not limited to the above embodiments, but may be variously modified without departing from the gist thereof. Of course.

[0071]

The effects obtained by typical ones of the inventions disclosed by the present application will be briefly described below.

(1) Since the optical waveguides are removed from the projections and recesses of the substrate, and the optical waveguides are arranged so as not to come into contact with the projections on the substrate, the bottom of the projections on the substrate, which is a concern in the conventional structure, is considered. The occurrence of stress concentration can be suppressed.

(2) By providing a plurality of types of protrusions having different heights at the optical element mounting positions on the substrate, it becomes possible to mount a plurality of types of optical elements having different structures on the same optical mounting substrate. .

(3) At the position where the optical element mounting portion of the substrate is formed, when the optical element is arranged, a convex portion whose height is set so that the position of the center of the core coincides with that of the optical waveguide is set in advance. After that, the formation / processing of the waveguide film and the processing of the mounting portion are sequentially performed, and the optical element is disposed thereon by using the exposed upper surface of the projection as a reference surface, thereby achieving high precision. Since the alignment in the height direction is performed, the mounting substrate can be easily manufactured without using a polishing step which is indispensable for manufacturing a conventional mounting substrate.

(4) Since a polishing step is unnecessary, problems such as surface deterioration due to polishing itself can be solved. Furthermore, in the conventional mounting board fabrication, when polishing is used, since the polishing amount cannot be precisely controlled, a structure requiring precision, such as a fiber guide groove or an alignment marker for mounting an optical element, is preliminarily mounted on the substrate. However, in the present invention, since a polishing step is not required, a structure requiring precision, such as a fiber guide groove or an alignment marker for mounting an optical element, is previously formed on a substrate. In particular, when Si is used as a substrate material, a high-precision structure can be manufactured by making full use of existing micromachine technology.

(5) In the production of a mounting substrate using conventional polishing, an organic material, which has been difficult to use as an optical waveguide material, can be used because a polishing step is not required.

(6) By the above-mentioned effects, polishing which requires a complicated process can be omitted, so that a great improvement in economic efficiency can be expected.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a mounting substrate for hybrid optical integration according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of each part in each step for explaining the method for manufacturing the mounting substrate for hybrid optical integration of the first embodiment.

FIG. 3 is an enlarged view near the electric wiring in FIG. 2 (e).

FIG. 4 is a diagram showing a schematic configuration of a mounting substrate for hybrid optical integration according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of each part in each step for explaining the method for manufacturing the mounting substrate for hybrid optical integration of the second embodiment.

FIG. 6 is a view showing a schematic configuration of a third embodiment of the mounting substrate for hybrid optical integration of the present invention.

FIG. 7 is a cross-sectional view of each part in each step for explaining the method for manufacturing the mounting substrate for hybrid optical integration of the third embodiment.

FIG. 8 is a diagram showing a schematic configuration of a fourth embodiment of the mounting substrate for hybrid optical integration of the present invention.

FIG. 9 is a cross-sectional view showing a cross section of each part in each step for explaining the method for manufacturing the hybrid optical integration mounting substrate of the fourth embodiment.

FIG. 10 is a diagram showing a schematic configuration of a fifth embodiment of the mounting substrate for hybrid optical integration of the present invention.

FIG. 11 is a cross-sectional view showing a cross section of each part in each step for explaining the method for manufacturing the hybrid optical integration mounting substrate of the fifth embodiment.

FIG. 12 is a diagram showing a schematic configuration of a sixth embodiment of the mounting substrate for hybrid optical integration of the present invention.

FIG. 13 is a view for explaining a problem of a conventional mounting substrate for hybrid optical integration.

FIG. 14 is a view for explaining a problem of a conventional method for manufacturing a mounting substrate for hybrid optical integration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Optical waveguide, 3 ... Optical element (LD), 11 ...
Optical element (PD), 4, 4a, 4b ... convex part (terrace part),
3a, 5: under cladding layer, 3b, 7: core, 3
c, 8: over cladding layer, 9: electric wiring, 9a: insulating SiO ₂ film, 9b: conductive pattern, 9c: solder film,
Reference numerals 10, 10a, 10b: gold mask, 12: optical fiber, 13: optical fiber guide groove, 14: optical fiber connection end face, 15: convex optical element alignment marker, 16: optical element electrode marker, 17 ... dielectric layer, 1
8: polyimide layer, 19: polymer waveguide, 40: slope side wall.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Anmitsuho 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Yoshinori Hibino 1-16-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Within Nippon Telegraph and Telephone Corporation (72) Inventor Ota Suzuki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-63-131104 (JP, A) JP-A Sho 60-49304 (JP, A) Lasers and Electro-Optics Society Annual Meeting, 1994. LEOS '94 Conference Proceedings. IEEE, Vol. 2, P. 271-272 (1994) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 6/12-6/14 G02B 6/26-6/27 G02B 6/30-6/35 G02B 6/42 -6/43 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A method according to claim 1, wherein the substrate has a concave portion and a convex portion.
Undercladding layer, core pattern,
A region including an optical waveguide formed of a lad layer and including the convex portion;
Is the optical element mounting section, and electrical wiring is provided on the optical element mounting section.
Method for fabricating a mounting substrate for hybrid optical integration
The substrate has concave portions and inclined side walls by wet etching.
A substrate processing step of forming a convex portion to be formed, and an undercladding layer having a predetermined thickness on the entire surface of the substrate.
After the formation, a core having a predetermined shape is formed on the undercladding layer.
Pattern and then over the entire surface of the substrate
An optical waveguide forming step of forming a clad layer, a convex portion having the inclined side wall of the substrate, and a concave portion near the convex portion;
Removing the optical waveguide to expose the surface
Process and an electric wiring forming process for forming an electric wiring pattern on the exposure
For hybrid optical integration, comprising:
How to make a mounting board . 2. The method according to claim 1, wherein the substrate is a silicon substrate.
The hybrid optical integration package according to claim 1, wherein:
How to make a substrate.