JP2003084157A - Method for manufacturing optical waveguide circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing for conveniently manufacturing an optical waveguide circuit furnished with an electric wiring, a pad for mounting and an electrode for light control or the like on the same plane with high accuracy of positions with respect to a core pattern of the optical waveguide. SOLUTION: A metallic pattern 13 composed of a core forming pattern 13a and a conductive part pattern 13b of the optical waveguide are formed on a metallic substrate 11 in a metallic pattern forming process, a clad layer 14 is formed by coating the metallic pattern 13 with a clad material in a clad layer forming process in a way that at least the core forming pattern 13a is partially exposed, a recess 14a having a core form is formed on the clad layer 14 by removing the core forming pattern 13a and the recess 14a is filled with a core material to form a core layer in a core forming process, thus, the optical waveguide circuit furnished with the optical waveguide, an electric wiring, the mounting pad and at least one kind of conductive part pattern for the electrode for light control is manufactured.

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 an optical waveguide circuit, and more particularly to an optical waveguide capable of collectively forming electric wiring, mounting pads, light control electrodes and the like and forming the optical waveguide. The present invention relates to a method for manufacturing a circuit.

[0002]

2. Description of the Related Art With the practical use of optical communication systems in recent years,
Various optical devices have been developed, and in particular, in an optical integrated circuit having an optical waveguide, it is required to establish an optical waveguide manufacturing technique and a high-precision mounting technique for an optoelectronic element such as a photodiode. Among them, the method of mounting an optoelectronic element in an optical integrated circuit requires a method in which the coupling loss of light between the optoelectronic element and the optical waveguide is small. The mounting method called the active alignment method, which is usually used, performs alignment so that the light intensity is actually passed through the optical waveguide and the output intensity is maximized, so it takes time and effort to observe the optical signal output, and the work efficiency is extremely poor. is there. Therefore, there is a demand for a passive alignment method that mounts components only by mechanical alignment, and as one method, a mounting method that uses the self-alignment effect in which components move due to surface tension generated during solder reflow is being studied. ing. In a printed circuit board having electric wiring, a pad for mounting such solder is produced together with the electric wiring by etching. However, on the optical waveguide substrate, a pad is formed by patterning by plating or sputtering in a step different from the step of forming the optical waveguide, which causes a problem such as an increase in the number of steps.

On the other hand, in order to reduce the cost of the optical waveguide forming method, there is a demand for a forming method which does not use the dry etching method such as reactive ion etching (RIE) which is low in manufacturing cost and lacks mass productivity. As a conventional optical waveguide forming method that does not use the dry etching method, for example, as in Japanese Patent Laid-Open No. 9-189818, a mold is prepared by plating using a polyimide uneven master plate, and the mold is used to form an optical waveguide. Have been reported. Further, Japanese Patent Laid-Open No. 8-313747 proposes a forming method using a metal mold.

[0004]

However, in the forming method disclosed in Japanese Patent Application Laid-Open No. 9-189818, RIE is required.
There is a problem that steps such as production of a polyimide original plate and formation of a peeling plating layer are required, and the steps in the die production step are difficult, resulting in low production cost and lack of mass productivity.
Furthermore, when performing multi-sided application on a large-area material during mass production, there is a difference in the film thickness distribution during the polyimide original plate manufacturing process and the film thickness distribution generated during the peeling plating layer formation process. There are problems such as a large difference in the diameter of the optical waveguide.

Further, in the method using a metal mold disclosed in Japanese Patent Laid-Open No. 8-313747, as described above, electric wiring, mounting pads, light control electrodes, etc. are newly formed in the post-process of forming the optical waveguide. Is required. Therefore, the number of steps is increased, and it is required to position the mounting pad extremely accurately with respect to the core pattern of the optical waveguide, which causes a problem that workability is extremely low. The present invention has been made in view of the above circumstances, and easily manufactures an optical waveguide circuit including electrical wiring, a mounting pad, an optical control electrode, and the like with high positional accuracy with respect to the core pattern of the optical waveguide. It aims at providing the manufacturing method for doing.

[0006]

In order to achieve such an object, the present invention comprises an optical waveguide and at least one conductive portion pattern of an electric wiring, a mounting pad and a light control electrode. In a method of manufacturing an optical waveguide circuit, a metal pattern forming step of forming a metal pattern including a core forming pattern of an optical waveguide and a conductive portion pattern on a metal substrate, and a clad so as to expose at least a part of the core forming pattern. A clad layer forming step of forming a clad layer by covering the metal pattern with a material, forming a core forming concave portion in the clad layer by removing the core forming pattern, and filling the concave portion with a core material. And a core layer forming step of forming a core layer.

As another aspect of the present invention, after the core layer forming step, a core layer burying step of further forming a clad layer so as to cover the exposed surface of the core layer is provided. As another aspect of the present invention, the metal substrate is a laminated substrate having different kinds of metal layers on the front surface side and the back surface side, and in the metal pattern forming step, the metal layer is formed on the metal layer on the front surface side of the laminated substrate. A pattern is formed, and in the clad layer forming step, a clad layer is formed so as to expose the metal layer on the back surface side of the laminated substrate, and after the core layer forming step, the metal layer on the back surface side of the laminated substrate is formed. A structure having a removing step of removing a part or all of the structure, and a structure having a core layer burying step of further forming a cladding layer so as to cover the exposed surface of the core layer after the removing step. And

The present invention provides a method of manufacturing an optical waveguide circuit, which comprises an optical waveguide and at least one conductive portion pattern of an electrical wiring, a mounting pad and a light control electrode,
A core layer forming step of forming an opening for forming a core of an optical waveguide on a metal substrate and filling the opening with a core material to form a core layer; and a pattern forming step of forming a conductive portion pattern on the metal substrate, A clad layer forming step of forming a clad layer by covering the core layer and the conductive part pattern with a clad material so as to expose at least a part of the core layer.

As another aspect of the present invention, after the clad layer forming step, a core layer burying step of further forming a clad layer so as to cover the exposed surface of the core layer is provided. As another aspect of the present invention, the metal substrate is a laminated substrate having different kinds of metal layers on a front surface side and a back surface side, and in the core layer forming step, an optical waveguide is formed on the metal layer on the front surface side of the laminated substrate. Forming an opening for forming a core, and filling the opening with a core material to form a core layer,
In the pattern forming step, the conductive portion pattern is formed on the metal layer on the front surface side of the laminated substrate, and in the clad layer forming step, the clad layer is formed so as to expose the metal layer on the back surface side of the laminated substrate. After the clad layer forming step, a configuration is provided that includes a removing step of removing a part or all of the metal layer on the back surface side of the laminated substrate so that at least the core layer is exposed. After that, a core layer burying step of further forming a clad layer so as to cover the exposed surface of the core layer was adopted.

In the present invention as described above, the metal substrate is used for forming the clad layer and core layer of the optical waveguide, and by selectively leaving the metal substrate, electric wiring, mounting pads, light control electrodes, etc. Will be configured.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIGS. 1 and 2 are process drawings showing an embodiment of a method for manufacturing an optical waveguide circuit of the present invention. In the method for manufacturing an optical waveguide circuit according to the present embodiment, first, in a metal pattern forming step, a resist pattern 12 is formed on the metal substrate 11 (FIG. 1A), and the metal substrate 11 is etched using the resist pattern 12 as a mask. Then, the core forming pattern 13a of the optical waveguide, and the conductive portion pattern 13b of at least one kind of the electric wiring, the mounting pad and the light controlling electrode,
A metal pattern 13 made of is formed, and the resist pattern 12 is removed (FIG. 1B). As the metal substrate 11, a plate-shaped or foil-shaped copper, stainless steel, or aluminum material is suitable. The metal pattern 1 including the core forming pattern 13a and the conductive portion pattern 13b
Although the formation of 3 is performed by etching in the illustrated example, it is not limited to this, and patterning may be performed by another method such as die punching.
In addition, after patterning the core forming pattern 13a and the conductive portion pattern 13b as described above, it is possible to perform a flattening process by plating for the purpose of eliminating the roughness (roughness) generated in the metal cross section due to the patterning. . Further, in order to prevent the metal components of the metal substrate 11 from melting into the material of the optical waveguide formed in the subsequent step, it is possible to form a barrier layer made of nickel (Ni) or the like by plating or the like.

Next, in the clad layer forming step, the metal pattern 13 (metal substrate 11) is coated with a clad material so that the back surface side of the metal pattern 13 including the core forming pattern 13a and the conductive portion pattern 13b is exposed. The clad layer 14 is formed (FIG. 1C). As the clad material, polymethyl acrylate (PMMA), polycarbonate (PC), epoxy resin, fluorinated polyimide, or the like can be used. When the clad material is in the form of varnish, it is applied on the metal pattern 13 by a coating means such as spin coating or die coating. When the clad material is in the form of a film, it is laminated on the metal pattern 13 by a laminator and then cured. Then, the clad layer 14 can be formed. The clad material attached to unnecessary portions during application is removed after application or after curing. As a removing method, a method such as dry etching or polishing can be used.

Next, in the core layer forming step, first,
Metal substrate 11 on which the clad layer 14 is formed as described above
A resist pattern 15 is formed on the back surface of the so as to cover the metal pattern 13 except the core forming pattern 13a (FIG. 1D), and the exposed core forming pattern 13 is formed.
The a is removed by etching to form a core forming recess 14a in the cladding layer 14 (FIG. 1E). next,
The resist pattern 15 is removed, and the formed recess 14a is filled with a core material to form a core layer 16 (FIG. 2).
(A)). The core material is polymethyl acrylate (PMM) whose refractive index is optimally adjusted with respect to the clad layer 14 described above.
A), polycarbonate (PC), epoxy resin, fluorinated polyimide, or the like can be used, and the core layer 16 can be formed by filling the recess 14a and then curing the same. The core material protruding from the recess 14a is removed by a method such as dry etching or polishing before or after curing.

The metal substrate 1 is formed by the above-mentioned metal pattern forming step, clad layer forming step, and core layer forming step.
1 is used to form the clad layer 14 and the core layer 16 of the optical waveguide, and the metal substrate 11 is selectively left to leave a conductive portion pattern 1 for electric wiring, mounting pads, light control electrodes, etc.
An optical waveguide circuit is formed by forming 3b. And
When the optical waveguide has a structure in which the core layer is embedded in the cladding layer, the following core layer embedding step is performed. That is, a resist pattern 17 is formed on the back surface of the metal substrate 11 so as to cover the conductive portion pattern 13b, and a clad layer 14 'is formed on a portion where the resist pattern 17 is not formed to expose the back surface side. The existing core layer 16 is covered with the cladding layer 14 '(FIG. 2 (B)). Also in this case, the clad material adhering to unnecessary portions is removed by a method such as dry etching or polishing before or after curing. After that, by removing the resist pattern 17, an optical waveguide having a structure in which the core layer is embedded in the clad layer can be obtained (FIG. 2C).

When the exposed conductive portion pattern 13b is a mounting pad, the metal base layer 18 may be formed of gold or the like and the solder bumps 19 may be formed by screen printing or the like in order to improve the bonding reliability. FIG. 2D). Further, the metal base layer 18 and the solder bumps 19 may be formed on the conductive portion pattern 13b before forming the clad layer 14 '. Further, a protective layer may be formed on the clad layer 14 '. This protective layer can be formed using, for example, photosensitive polyimide.

Second Embodiment FIGS. 3 and 4 are process drawings showing another embodiment of the optical waveguide circuit manufacturing method of the present invention. In this embodiment, as the metal substrate, the front side metal layer 21a and the back side metal layer 2 are used.
A laminated substrate 21 different from 1b is used. First, in a metal pattern forming step, a resist pattern 22 is formed on the front side metal layer 21a of the laminated substrate 21 (see FIG. 3).
(A)), using the resist pattern 22 as a mask, the front-side metal layer 21a is selectively etched, and the core forming pattern 23a of the optical waveguide and at least one kind of conductive material of the electrical wiring, the mounting pad, and the light control electrode are formed. Part pattern 2
A metal pattern 23 composed of 3b and 3b is formed, and the resist pattern 22 is removed (FIG. 3B). Metallic layers 21a and 21b of different types that compose the laminated substrate 21 used
As a combination of various metal materials is possible. For example, the metal layer 21a on the front surface side can be made of a material that functions as an electric wiring, a mounting pad, a light control electrode, or the like. Further, the metal layer 21b on the back surface side functions as a support for the metal layer 21a, functions as a barrier metal when the mounting pad structure is formed on the metal layer 21a, and can be peeled off even after high temperature heating. It can be a material that functions as a metal resist. Considering heat resistance, etching selectivity, reliability in forming mounting pads, and the like, for example, the metal layer 21a is a copper layer and the metal layer 21b is
Can be a copper-nickel laminated substrate in which is a nickel layer. By using such a laminated substrate 21, since the metal pattern 23 formed on the metal layer 21a is supported by the metal layer 21b on the back surface side, the metal pattern 23 is independently located at a position separated from other patterns or the substrate 21. It is possible to form the metal pattern 23 including the pattern.

In the selective etching of the surface side metal layer 21a, an etching solution that dissolves the metal layer 21a but does not dissolve the metal layer 21b, or the etching rate of the metal layer 21b is remarkably higher than that of the metal layer 21a. It can be done using a slow etchant. For example, when the laminated board 21 is a copper-nickel laminated board,
The selective etching of the copper layer as the metal layer 21a can be performed using a commercially available organic ammonia-based alkaline etching solution.

After patterning the core forming pattern 23a and the conductive portion pattern 23b by the selective etching as described above, a plating process is performed for the purpose of eliminating the roughness (roughness) generated on the metal cross section by the patterning. It can also be flattened. Further, a barrier layer made of nickel (Ni) or the like may be formed by plating or the like in order to prevent the metal component of the metal layer 21a of the laminated substrate 21 from melting into the material of the optical waveguide formed in a later step. It is possible.

Next, in the clad layer forming step, the metal pattern 23 consisting of the core forming pattern 23a and the conductive portion pattern 23b formed on the metal layer 21a is covered with a clad material so that the metal layer 21b on the back surface is exposed. A clad layer 24 is formed on the substrate (FIG. 3C). The clad material used for the clad layer 24 and the forming method are
It can be similar to the cladding layer 14 in the above-described embodiment.

Next, in the core layer forming step, first,
A resist pattern 25 is formed in a desired shape on the metal layer 21b on the back surface so as to cover a portion of the metal pattern 23 where the metal pattern 23 is formed except the core forming pattern 23a (FIG. 3D). Next, the exposed metal layer 21
b is removed by etching, and further, the core forming pattern 23a is removed by etching.
4, a core forming recess 24a is formed (see FIG. 3).
(E)). Next, the resist pattern 25 is removed, and the formed recesses 24a are filled with a core material to form a core layer 26 (FIG. 4A). The exposed metal layer 21b and the core forming pattern 23a are removed by etching, for example, when the laminated substrate 21 is a copper-nickel laminated substrate. Can be used to etch away the nickel layer as the metal layer 21b, and then the core forming pattern 23a can be removed by etching using the above-described copper etching solution. Alternatively, the etching removal of the metal layer 21b and the core formation pattern 23a may be continuously performed using an etching solution capable of dissolving both copper and nickel. The core material used for the core layer 26 may be the same as the core layer 16 in the above-described embodiment, for which the refractive index of the cladding layer 24 is optimally adjusted.

Next, in the removing step, the metal layer 21b on the back surface side is removed so that the desired portions of the conductive portion pattern 23b are electrically independent (FIG. 4B). The metal layer 21b left in this way functions as an external connection electrode.

Through the above-mentioned metal pattern forming step, clad layer forming step, core layer forming step, and removing step, the laminated substrate 21 is used to form the clad layer 24 and the core layer 26 of the optical waveguide, and the laminated layers are formed. Front side metal layer 2 of substrate 21
1a and the back surface side metal layer 21b are selectively left, and the conductive portion pattern 2 such as electric wiring, mounting pads, light control electrodes, etc.
By forming 3b, an optical waveguide circuit can be formed.

In the case of an optical waveguide having a structure in which the core layer is embedded in the cladding layer, the core layer is embedded in the next core layer embedding step. That is, the cladding layer 24 ′ is formed so as to cover the exposed back surface side of the core layer 26.
By forming the optical waveguide, it is possible to obtain an optical waveguide having a structure in which the core layer is embedded in the cladding layer (see FIG. 4).
(C)). Also in this case, the clad material adhering to unnecessary portions is removed by a method such as dry etching or polishing before or after curing. If the metal layer 21b is unnecessary, the metal layer 21b may be removed again by etching to expose the conductive portion pattern 23b (metal layer 21a) on the clad layer 24 'side.

Further, when the conductive portion pattern 23b is a mounting pad, the metal base layer 28 may be formed of gold or the like in order to improve the bonding reliability, and the solder bumps 29 may be formed by screen printing or the like (FIG. 4). (D)). In this case, the metal layer 21b left on the conductive portion pattern 23b
Acts as a barrier metal that prevents diffusion of the conductive portion pattern 23b. The metal base layer 28 and the solder bumps 29 may be formed on the conductive portion pattern 23b (metal layer 21b) before forming the clad layer 24 '. Further, a protective layer may be formed on the clad layer 24 '. This protective layer can be formed using, for example, photosensitive polyimide.

Third Embodiment FIGS. 5 and 6 are process diagrams showing another embodiment of the method for manufacturing an optical waveguide circuit according to the present invention. In the present embodiment, first, in the core layer forming step, a resist pattern 32 is formed on the front surface side of the metal substrate 31 (FIG. 5A), and the metal substrate 31 is etched by using this resist pattern 32 as a mask. An opening 33 for forming the core of the waveguide is formed and the resist pattern 32 is removed (FIG. 5 (B)).
As the metal substrate 31, a plate-shaped or foil-shaped copper, stainless steel, or aluminum material is suitable. still,
Although the formation of the opening 33 for forming the core is performed by etching in the illustrated example, the present invention is not limited to this. For example, patterning may be performed by another method such as die punching. In addition, after the core-shaped opening 33 is formed as described above, it is possible to perform a flattening process by plating for the purpose of eliminating the roughness (roughness) generated in the metal cross section. Further, in order to prevent the metal components of the metal substrate 31 from melting into the core layer 34 formed next, it is possible to form a barrier layer made of nickel (Ni) or the like by plating or the like.

Next, the opening 33 is filled with a core material to form a core layer 34 (FIG. 5C). As the core material, polymethyl acrylate (PMMA), polycarbonate (PC), epoxy resin, fluorinated polyimide, or the like can be used. If the core material is varnished,
It is applied on the metal substrate 31 by an application means such as spin coating or die coating, and when the core material is in the form of a film, it is laminated on the metal substrate 31 by a laminator and then cured to form the core layer 34. be able to. In addition, the core material attached to unnecessary parts during application is
It is removed after coating or curing, and as a removing method, a method such as dry etching or polishing can be used.

Next, in a pattern forming step, a resist pattern 35 is formed on the metal substrate 31 on which the core layer 34 is formed.
Is formed (FIG. 5D), the metal substrate 31 is etched using the resist pattern 35 as a mask to form at least one conductive portion pattern 36 of an electric wiring, a mounting pad and a light control electrode, Resist pattern 35
Are removed (FIG. 5 (E)).

Next, in the clad layer forming step, the core layer 34 and the conductive part pattern 36 are covered with the clad material so as to expose the back surface side of the core layer 34 and the back surface side of the conductive part pattern 36, and the clad layer 37. (Fig. 6)
(A)). The clad material is polymethyl acrylate (PMM) whose refractive index is optimally adjusted with respect to the core layer 34.
A), polycarbonate (PC), epoxy resin, fluorinated polyimide, etc. can be used. The clad material attached to unnecessary portions can be removed by a method such as dry etching or polishing before or after curing.

The metal substrate 31 is formed by the core layer forming step, the pattern forming step, and the clad layer forming step described above.
Is used to form the core layer 34 and the cladding layer 37 of the optical waveguide, and the metal substrate 31 is selectively left to leave electrical wiring,
The optical waveguide circuit can be formed by forming the conductive portion pattern 36 such as the mounting pad and the light control electrode. Then, in the case of forming an optical waveguide having a structure in which the core layer is embedded in the cladding layer, the following core layer embedding step is performed. That is, a resist pattern 38 is formed on the back surface of the metal substrate 31 so as to cover the conductive portion pattern 36, and a clad layer 37 ′ is formed on a portion where the resist pattern 38 is not formed, thereby exposing the back surface side. The existing core layer 34 is covered with a clad layer 37 '(FIG. 6 (B)). Also in this case, the clad material adhering to unnecessary portions is removed by a method such as dry etching or polishing before or after curing. After that, by removing the resist pattern 38, an optical waveguide having a structure in which the core layer is embedded in the clad layer can be obtained (FIG. 6C).

When the exposed conductive portion pattern 36 is a mounting pad, the metal base layer 39 may be formed of gold or the like and the solder bump 40 may be formed by screen printing or the like in order to improve the bonding reliability. FIG. 6D). Further, the metal base layer 39 and the solder bumps 40 may be formed on the conductive portion pattern 36 before forming the clad layer 37 ′. Further, a protective layer may be formed on the clad layer 37 '. This protective layer can be formed using, for example, photosensitive polyimide.

Fourth Embodiment FIGS. 7 and 8 are process charts showing another embodiment of the optical waveguide circuit manufacturing method of the present invention. In this embodiment, as the metal substrate, the metal layer 41a on the front surface side and the metal layer 4 on the back surface side are used.
A laminated substrate 41 different from 1b is used. Then, in the core layer forming step, the front side metal layer 41 of the laminated substrate 41
A resist pattern 42 is formed on a (FIG. 5 (A)), and the resist pattern 42 is used as a mask to form the front side metal layer 4
1a is selectively etched to form an opening 43 for forming the core of the optical waveguide, and the resist pattern 42 is removed (FIG. 7B). The laminated substrate 41 used can be the same as the laminated substrate 21 described above. The selective etching of the surface side metal layer 41a is performed by an etching solution that dissolves the metal layer 41a but does not dissolve the metal layer 41b, or
The etching can be performed using an etching solution in which the etching rate of the metal layer 41b is significantly lower than the etching rate of the metal layer 41a. For example, when the laminated substrate 41 is a copper-nickel laminated substrate, selective etching of the copper layer as the metal layer 41a can be performed using a commercially available organic ammonia-based alkaline etching solution.

After the opening 43 for forming the core is formed by the selective etching as described above, it may be flattened by plating for the purpose of eliminating the roughness (roughness) generated in the metal cross section. it can. Further, a barrier layer made of nickel (Ni) or the like may be formed by plating or the like in order to prevent the metal component of the metal layer 41a of the laminated substrate 41 from melting into the core layer 44 formed next. Is.

Next, the opening 43 is filled with a core material to form a core layer 44 (FIG. 7C). The core material used for the core layer 44 and the forming method thereof may be the same as those of the core layer 34 in the above-described embodiment. Next, in a pattern forming step, a resist pattern 45 is formed on the metal layer 41a on the surface side of the laminated substrate 41 on which the core layer 44 is formed (FIG. 7D), and the metal pattern 41a is used as a mask. Etching the
At least one kind of conductive portion pattern 46 of the electric wiring, the mounting pad and the light control electrode is formed, and the resist pattern 45 is removed (FIG. 7E).

Next, in the clad layer forming step, the core layer 44 and the conductive portion pattern 46 formed on the metal layer 41a are formed.
Is covered with a clad material to form a metal layer 41b on the back surface side.
The cladding layer 47 is formed so that the exposed portion is exposed (FIG. 8).
(A)). As the clad material to be used, similar to the clad material of the clad layer 37 in the above-described embodiment, a material with the refractive index optimally adjusted for the core layer 44 can be used. The clad material attached to unnecessary portions can be removed by a method such as dry etching or polishing before or after curing.

Next, in a removing step, a resist pattern having a desired shape is formed on the metal layer 41b on the back surface side, and the unnecessary metal layer 41b is removed by etching using this resist pattern as a mask (FIG. 8B). The metal layer 41b left in this way functions as an external connection electrode.

Through the above-mentioned core layer forming step, pattern forming step, clad layer forming step, and removing step, the laminated substrate 41 is used to form the core layer 44 and the clad layer 47 of the optical waveguide, and the laminated substrate 41 front surface side metal layer 4
1a, electrical wiring with the back side metal layer 41b selectively left,
An optical waveguide circuit is formed by forming a conductive portion pattern 46 such as a mounting pad and a light control electrode.

In the case where the optical waveguide has a structure in which the core layer is embedded in the cladding layer, the core layer is embedded in the next core layer embedding step. That is, the cladding layer 47 'is formed so as to cover the exposed back surface side of the core layer 44.
By forming the optical waveguide, an optical waveguide having a structure in which the core layer is embedded in the cladding layer can be obtained (FIG. 8).
(C)). Also in this case, the clad material adhering to unnecessary portions is removed by a method such as dry etching or polishing before or after curing. If the metal layer 41b is unnecessary, the metal layer 41b can be removed by etching again to expose the conductive portion pattern 46 (metal layer 41a) on the clad layer 47 'side.

When the conductive portion pattern 46 is a mounting pad, a metal base layer 48 is formed of gold or the like to improve the bonding reliability, and the solder bump 4 is formed by screen printing or the like.
9 can be formed (FIG. 8D). in this case,
The metal layer 41b left on the conductive portion pattern 46 acts as a barrier metal that prevents diffusion of the conductive portion pattern 46.

Before forming the clad layer 47 ', the metal base layer 48 and the solder bump 49 may be formed on the conductive portion pattern 46 (metal layer 41b). Also,
To expose the metal layer 41b left on the conductive portion pattern 46 or to expose the solder bump 49,
A protective layer may be formed on the clad layer 47 '. This protective layer can be formed using, for example, photosensitive polyimide.

In the present invention, the conductive substrate pattern is formed by leaving the desired portion of the metal layer 41b on the back surface side, and the laminated substrate 41 described above is used.
Of the conductive portion pattern 46 formed on the metal layer 41a on the front surface side of the
A conductive portion pattern different from that may be used. Such an embodiment will be described with reference to FIG. In this embodiment,
First, the same core layer forming step (FIGS. 7A to 7C) as in the above-described fourth embodiment is completed. Next, in the pattern forming step, the laminated substrate 4 on which the core layer 44 is formed
A resist pattern 45 'on the metal layer 41a on the front surface side
Is formed (FIG. 9A), and this resist pattern 45 'is formed.
The metal layer 41a is etched by using the as a mask to form the electrical wiring and at least one conductive part pattern 46 of the light control electrode. Then, similarly to the fourth embodiment described above, in the clad layer forming step, the clad layer 47 is formed so that the metal layer 41b on the back surface side is exposed (FIG. 9B).

Next, in the removing step, a resist pattern is formed on the back side metal layer 41b so as to form a pattern different from the conductive portion pattern 46 formed on the front side metal layer 41a, and this resist pattern is formed. The metal layer 41b unnecessary as a mask is removed by etching (FIG. 9C).
The metal layer 41b thus left serves as, for example, an external connection electrode (mounting pad) as a conductive portion pattern 46 'different from the conductive portion pattern 46 formed on the front side metal layer 41a.

By the core layer forming step, the pattern forming step, the clad layer forming step and the removing step as described above,
The laminated substrate 41 is used to form the core layer 44 and the clad layer 47 of the optical waveguide, and the front surface side metal layer 41a and the rear surface side metal layer 41b of the laminated substrate 41 are selectively left to leave electrical wiring and mounting pads. , Conductive part pattern 4 such as light control electrode
6, 46 'are formed to form an optical waveguide circuit.

When the optical waveguide has a structure in which the core layer is embedded in the clad layer, the core layer can be embedded in the core layer embedding step as in the fourth embodiment. Further, when the conductive portion pattern 46 'is a mounting pad, the metal base layer 48 can be formed of gold or the like in order to enhance the bonding reliability, and the solder bump 49 can be formed by screen printing or the like (FIG. 9D. )).

[0044]

EXAMPLES Next, the present invention will be described in more detail by showing more specific examples. Example 1 As a metal substrate, a copper layer having a thickness of 50 μm,
A copper-nickel laminated substrate in which a nickel layer having a thickness of 10 μm was provided on the back surface of this copper layer by electrolytic plating was prepared.

Using this copper-nickel laminated substrate, an optical waveguide circuit was prepared as follows according to the steps of the above-mentioned fourth embodiment. First, a dry film resist (Sunfort manufactured by Asahi Kasei Co., Ltd.) is laminated on the copper layer of the copper-nickel laminated substrate, and exposed and developed through a predetermined photomask to form an opening pattern of an optical waveguide core shape. A resist pattern having the same was formed. Next, using an organic ammonia-based alkaline etching solution (A-Process manufactured by Meltex Co., Ltd.), the copper layer on the front surface side is selectively etched without dissolving the nickel layer on the back surface to form an optical waveguide core. Openings were formed in the copper layer. Then, the resist pattern was peeled and removed using an alkaline stripping solution (3% sodium hydroxide aqueous solution).

Then, the opening for core formation formed in the copper layer as described above is filled with fluorinated polyimide as an optical waveguide core material by a spin coating method, and heated at 350 ° C. for hardening treatment. The fluorinated polyimide protruding from the opening was removed by polishing. As a result, a core layer having a cross-sectional dimension of 50 μm × 50 μm was formed.
(The above is the core layer forming step)

Next, the same dry film resist as above is laminated on the copper layer on which the core layer is formed as described above, and exposed and developed through a predetermined photomask to mount the copper layer on the copper layer. A resist pattern was formed on the portion to be left as a pad for use. As shown in FIG. 10, this resist pattern has a square pattern of 0.5 mm on a side of about 0.5 mm from the core layer (the portion shown by the diagonal lines).
And were arranged at a pitch of 2 mm (2 columns and 2 rows) along the axial direction of the core layer. Next, using the organic ammonia-based alkaline etching solution described above, the copper layer on the front surface side is selectively etched without dissolving the nickel layer on the back surface to form a conductive pattern (mounting pad) made of the copper layer. did. After that, the resist pattern was peeled off using the above alkaline stripping solution.
(The above is the pattern forming process)

Next, a fluorinated polyimide having a refractive index optimally adjusted for the above core layer is prepared as a clad material, and this clad material is applied by a spin coating method so as to cover the core layer and the mounting pad. Then, it was heated at 350 ° C. for hardening treatment. As a result, a clad layer having a thickness of 60 μm was formed. (The above is the clad layer forming step)

Next, a dry film resist (Sunfort manufactured by Asahi Kasei Co., Ltd.) is laminated on the nickel layer on the back surface side, and exposed and developed through a predetermined photomask to form a conductive portion made of the above copper layer. A resist pattern was formed on the nickel layer corresponding to the pattern position.
Then, using the above resist pattern as a mask, a nickel layer on the back surface side was formed by using a persulfate-based etching solution (top lip RSII manufactured by Okuno Chemical Industries Co., Ltd.) without dissolving the mounting pad made of a copper layer. Was selectively etched to form a conductive portion pattern (mounting pad) made of a nickel layer on the conductive portion pattern made of a copper layer. After that, the resist pattern was peeled off using the above alkaline stripping solution. (Above, removal process)

Next, the same clad material as described above was applied from the nickel layer side by a spin coating method so as to cover the core layer, and heated at 350 ° C. for hardening treatment. Then, polishing was performed so that the nickel layer (mounting pad) was exposed to form a clad layer having a thickness of 10 μm, and the core layer was embedded. (The above is the core layer embedding process)

Then, a gold plating layer is formed on the nickel layer (mounting pad) by electroless plating, and a photosensitive polyimide (Photo Nice, manufactured by Toray Industries, Inc.) is applied on the back side cladding layer. The protective layer was formed by exposing and developing to expose the nickel layer (mounting pad).
Then, a solder paste was screen-printed on the gold plating layer and melted by reflow to form solder bumps. An optical waveguide circuit was produced by the above steps. This optical waveguide circuit can be mounted on a printed circuit board or the like via solder bumps, and has a nickel layer as a barrier metal between a mounting pad made of a copper layer and a gold plating layer.

Example 2 First, in the same manner as in Example 1, the steps up to the core layer forming step were performed. Next, according to the embodiment shown in FIG. 9 described above, an optical waveguide circuit was manufactured as follows. That is, by laminating the same dry film resist as in Example 1 on the copper layer on which the core layer is formed as described above, and exposing and developing it through a predetermined photomask, the electrode and the electrical property of the copper layer are reduced. A resist pattern was formed on the portions to be left as wiring. A resist pattern was formed. This resist pattern is, as shown in FIG. 11, a pattern having a width of 50 μm and a length of 500 μm for electrodes, which are provided in parallel on both sides of the optical waveguide core layer (the portion shown by the diagonal lines), and a process described later. An L-shaped pattern for electrical wiring with a mounting pad (portion shown by a chain line) formed by leaving the nickel layer is used.

Next, the organic layer-based alkaline etching solution used in Example 1 was used to selectively etch the copper layer on the front surface side without dissolving the nickel layer on the back surface to form a conductive pattern of the copper layer. (Electrodes and electrical wiring)
Was formed. After that, the resist pattern was peeled off using the above alkaline stripping solution. (The above is the pattern forming process)

Next, fluorinated polyimide having a refractive index optimally adjusted for the above core layer is prepared as a clad material, and this clad material is spun so as to cover the core layer and the conductive pattern (electrodes and electrical wiring). It was applied by a coating method and heated at 350 ° C. to be cured. As a result, a clad layer having a thickness of 60 μm was formed. (that's all,
Clad layer forming process)

Next, a dry film resist similar to that of Example 1 is laminated on the nickel layer on the back surface side, and exposed and developed through a predetermined photomask to form a resist on the nickel layer portion to be left as a mounting pad. A pattern was formed. Then, using the above resist pattern as a mask, a perhydrosulfuric acid-based etching solution similar to that used in Example 1 was used to dissolve the conductive pattern (electrodes and electrical wiring) made of a copper layer without dissolving the nickel layer on the back surface side. Was selectively etched to form a conductive portion pattern (mounting pad). The conductive portion pattern (mounting pad) is connected to the electrode through the electric wiring made of the copper layer. After that, the resist pattern was peeled off using the above alkaline stripping solution. (Above, removal process)

Next, the same clad material as that described above was applied from the nickel layer side by a spin coating method so as to cover the core layer, and heated at 350 ° C. for hardening treatment. Then, polishing was performed so that the nickel layer (mounting pad) was exposed to form a clad layer having a thickness of 10 μm, and the core layer was embedded. (The above is the core layer embedding process)

Next, a gold plating layer is formed on the nickel layer (mounting pad) by electroless plating, and a photosensitive polyimide (Photo Nice manufactured by Toray Industries, Inc.) is applied on the back side cladding layer. The protective layer was formed by exposing and developing to expose the nickel layer (mounting pad).
Then, a solder paste was screen-printed on the gold plating layer and melted by reflow to form solder bumps. An optical waveguide circuit was produced by the above steps. In this optical waveguide circuit, the optical waveguide, electrical wiring, and electrodes are mixedly mounted,
It can be mounted on a printed circuit board or the like via solder bumps, and is provided with a gold plating layer for improving joint reliability.

[0058]

As described in detail above, according to the present invention, in the metal pattern forming step, a metal pattern including a core forming pattern of an optical waveguide and a conductive portion pattern is formed on a metal substrate, and then the clad is formed. Layer or core layer, or after forming the core layer on the metal substrate, forming the conductive portion pattern on the metal substrate in the pattern forming step, and then forming the clad layer. Since the substrate is used to form the clad layer and core layer of the optical waveguide, and this is selectively left as the conductive part pattern to form the electrical wiring, mounting pads, light control electrodes, etc. Positional accuracy with wiring, mounting pads, light control electrodes, etc. is extremely high, and the optical waveguide and electrical wiring, mounting pads, light control electrodes, etc. can be formed collectively. In addition, it is possible to prevent an increase in the number of steps, eliminate the need for expensive and low-workability dry etching such as RIE, and reduce the manufacturing cost. It is possible to manufacture an optical waveguide circuit with uniform quality by mass production by multi-face attachment.

[Brief description of drawings]

FIG. 1 is a process chart showing an embodiment of a method for manufacturing an optical waveguide circuit of the present invention.

FIG. 2 is a process drawing showing an embodiment of the optical waveguide circuit manufacturing method of the present invention.

FIG. 3 is a process drawing showing another embodiment of the optical waveguide circuit manufacturing method according to the present invention.

FIG. 4 is a process drawing showing another embodiment of the optical waveguide circuit manufacturing method according to the present invention.

FIG. 5 is a process drawing showing another embodiment of the optical waveguide circuit manufacturing method according to the present invention.

FIG. 6 is a process drawing showing another embodiment of the optical waveguide circuit manufacturing method according to the present invention.

FIG. 7 is a process drawing showing another embodiment of the optical waveguide circuit manufacturing method according to the present invention.

FIG. 8 is a process drawing showing another embodiment of the optical waveguide circuit manufacturing method of the present invention.

FIG. 9 is a process drawing showing another embodiment of the optical waveguide circuit manufacturing method according to the present invention.

FIG. 10 is a drawing for explaining the optical waveguide circuit manufacturing method according to the first embodiment of the present invention.

FIG. 11 is a drawing for explaining the optical waveguide circuit manufacturing method according to the first embodiment of the present invention.

[Explanation of symbols]

11 ... Metal substrate 21 ... laminated substrate 21a ... front side metal layer 21b ... Back side metal layer 13, 23 ... Metal pattern 13a, 23a ... Core forming pattern 13b, 23b ... Conductive part pattern 14, 14 ', 24, 24' ... Cladding layer 14a, 24a ... Recesses 16, 26 ... Core layer 31 ... Metal substrate 41 ... Laminated substrate 41a ... Front side metal layer 41b ... Back side metal layer 33, 43 ... Opening 34, 44 ... Core layer 36, 46, 46 '... Conductive pattern 37, 37 ', 47, 47' ... Cladding layer

Claims (8)

[Claims] 1. A method for manufacturing an optical waveguide circuit, comprising: an optical waveguide; and a conductive portion pattern of at least one kind of an electrical wiring, a mounting pad, and a light control electrode. A metal pattern forming step of forming a metal pattern composed of a pattern and a conductive part pattern; forming a clad layer by covering the metal pattern with a clad material so as to expose at least a part of the core forming pattern A core layer forming step of forming a core forming recess in the clad layer by removing the core forming pattern, and filling the recess with a core material to form a core layer. And a method for manufacturing an optical waveguide circuit. 2. The optical waveguide circuit according to claim 1, further comprising a core layer embedding step of forming a clad layer so as to cover the exposed surface of the core layer after the core layer forming step. Manufacturing method. 3. The metal substrate is a laminated substrate having different kinds of metal layers on the front surface side and the back surface side, and in the metal pattern forming step, the metal pattern is formed on the metal layer on the front surface side of the laminated substrate. Then, in the clad layer forming step, a clad layer is formed so as to expose the metal layer on the back surface side of the laminated substrate, and after the core layer forming step, a part of the metal layer on the back surface side of the laminated substrate or The method for manufacturing an optical waveguide circuit according to claim 1, further comprising a removing step of removing all of the layers. 4. The manufacturing of an optical waveguide circuit according to claim 3, further comprising a core layer embedding step of forming a clad layer so as to cover the exposed surface of the core layer after the removing step. Method. 5. A method of manufacturing an optical waveguide circuit, comprising: an optical waveguide; and a conductive portion pattern of at least one of electrical wiring, a mounting pad, and a light control electrode, which is used for forming a core of the optical waveguide on a metal substrate. Core layer forming step of forming an opening and filling the opening with a core material to form a core layer; pattern forming step of forming a conductive portion pattern on the metal substrate; exposing at least a part of the core layer A clad layer forming step of forming the clad layer by covering the core layer and the conductive part pattern with a clad material as described above. 6. The optical waveguide circuit according to claim 5, further comprising a core layer embedding step of further forming a clad layer so as to cover the exposed surface of the core layer after the clad layer forming step. Manufacturing method. 7. The metal substrate is a laminated substrate having different kinds of metal layers on a front surface side and a back surface side, and for forming an optical waveguide on the metal layer on the front surface side of the laminated substrate in the core layer forming step. Forming an opening and filling the opening with a core material to form a core layer; in the pattern forming step, forming the conductive portion pattern on the metal layer on the front surface side of the laminated substrate; In the forming step, a clad layer is formed so as to expose the metal layer on the back surface side of the laminated substrate, and after the clad layer forming step, at least the core layer is exposed so that the metal layer on the back surface side of the laminated substrate is exposed. The method for manufacturing an optical waveguide circuit according to claim 5, further comprising a removing step of removing a part or all of the above. 8. The manufacturing of an optical waveguide circuit according to claim 7, further comprising a core layer embedding step of forming a clad layer so as to cover the exposed surface of the core layer after the removing step. Method.