JPH0667044A - Optical circuit and electric circuit mixed substrate - Google Patents

Abstract

PURPOSE:To obtain the optical circuit and electric circuit mixed substrate which facilitates size reduction, high-speed processing of light signals, and variation in light signal wavelength and is superior in economy by mounting respective functional elements on the substrate in a bare chip state. CONSTITUTION:An electric circuit 2 and an optical circuit 3 are formed on the surface of a semiconductor substrate 1 such as an Si substrate and a light emitting element such as an LED (or light receiving element such as a PD) and a communication control element 5 are mounted in a bare chip state. The electric circuit 2 is formed of aluminum wiring, etc., formed in specific pattern by, for example, a lift-off. The optical circuit 3, on the other hand, is formed by forming grooves in, for example, the substrate 1 by etching, etc., and embedding an organic material such as polyimide in the grooves by spin coating, etc. Further, the light emitting element 3 and communication control element 5 are fixed in a recessed part 7 formed at a specific position on the substrate 1 and the electrodes of the light emitting element 4 and communication control element 5 and the electric circuit 2 are connected with a bonding wire (or TAB lead) 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication system such as an optical CATV in which a signal sent to the subscriber side (TV image information etc.) or a signal sent from the subscriber side (channel selection signal etc.) is electrically transmitted on the way. The present invention relates to an optical circuit / electric circuit mixed board used for a device for converting into a signal and amplifying the signal.

[0002]

2. Description of the Related Art Conventionally, the following modules have been used in this type of apparatus. (A) A module in which an O / E or E / O conversion unit, an electric signal amplification unit, and an optical branching / merging unit are each composed of components, and these components are mounted on a substrate together with a packaged communication control element. (B) A module in which an optical waveguide formed of an inorganic material such as LiNbO ₃ and a light emitting element or a light receiving element are connected to each other to form a unit, and this unit is mounted on a substrate together with a communication control element. (C) A monolithic LSI module in which a light emitting element or a light receiving element, a communication control element, and an optical waveguide are formed on a semiconductor substrate such as GaAs.

[0003]

As for (a) and (b), it is difficult to miniaturize because various parts are combined, and the signal line length connecting each part becomes long in order to increase the speed of the optical signal. Speed limits. Since (c) is a monolithic LSI, the product yield is multiplied by the yield of each functional element (light emitting element or light receiving element, communication control element) and optical waveguide, which is not economical, and it is not easy to change the optical signal wavelength. Absent.

[0004]

In view of the above problems, the present invention provides a compact optical circuit, a high-speed optical signal processing, an easy change of the optical signal wavelength, and an economical mixed optical circuit / electric circuit mounting. The first configuration is to provide a substrate, in which an optical circuit is formed of an organic material on a substrate on which an electric circuit is formed, and functional elements such as a light emitting element, a light receiving element and a communication control element are placed at predetermined positions in a bare chip state. It is characterized by being installed in.

In the second structure, a coating layer made of an organic material having a low dielectric constant and a refractive index lower than that of the material of the optical circuit is formed on the substrate having the optical circuit formed of the organic material. It is characterized in that an electric circuit is formed on it, and functional elements such as a light emitting element, a light receiving element and a communication control element are mounted in a bare chip state at predetermined positions.

[0006]

In the present invention, since each functional element (light emitting element or light receiving element, communication control element) is mounted on the substrate in a bare chip state, the signal line length can be shortened and miniaturization can be achieved. The upper limit of communication speed is expanded. Particularly in the second configuration, the electric circuit is formed on the coating layer having a low dielectric constant, so that the signal delay is significantly improved. The change of the optical signal wavelength can be easily dealt with by replacing the light emitting element or the light receiving element. Furthermore, since each functional element can be selected in advance,
The product yield is high and the economy is excellent.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 3 show an embodiment of the present invention corresponding to claim 1. In the figure, reference numeral 1 is a semiconductor substrate such as a Si substrate, on which an electric circuit 2 and an optical circuit 3 are formed, and a light emitting element (or a light receiving element such as PD) 4 such as an LED and a communication control element 5 are bare chips. It is installed in the state of.

The electric circuit 2 is made of, for example, aluminum wiring formed in a predetermined pattern by lift-off. The optical circuit 3 is formed, for example, by forming a groove 6 (see FIG. 3) in the substrate 1 by etching or the like and filling the groove 6 with an organic material such as polyimide by means such as spin coating. Further, the light emitting element 4 and the communication control element 5 are fixed in a recess 7 formed at a predetermined position of the substrate 1, and the electrodes of these elements 4 and 5 and the electric circuit 2 are connected by a bonding wire (or TAB lead) 8. .

Although the optical circuit 3 is formed in the groove 3 of the substrate 1 in the above embodiment, the optical circuit 3 is formed in the substrate 1 as shown in FIG.
It can also be formed so as to project from the surface of the. In this case, it is desirable to provide a coating layer 9 made of an organic material (polyimide or the like) having a lower refractive index than the material of the optical circuit 3 so as to cover the optical circuit 3.

If the light emitting element (or the light receiving element) or the communication control element generates a large amount of heat, as shown in FIG.
A heat sink 1 for making a hole 11 in the hole and fixing and supporting a light emitting element 4 and a communication control element (not shown) in the hole 11.
2 should be provided. The heat sink 12 is fixed to the back surface of the substrate 1 with an adhesive or solder 13.

Next, FIGS. 6 to 8 show another embodiment of the present invention corresponding to the second aspect. This optical circuit / electrical circuit mixed substrate is a semiconductor substrate 1 such as a Si substrate on which an optical circuit 3 made of an organic material such as polyimide is formed by a photolithography technique, and a low dielectric constant and an optical circuit 3 of the optical circuit 3 are formed thereon. A coating layer 9 made of an organic material (such as polyimide) having a refractive index lower than that of the material is formed, an electric circuit 2 is formed on the coating layer 9, and a light emitting element (or a light receiving element) 4 is provided at a predetermined position on the substrate 1. Also, the communication control element 5 is mounted in a bare chip state.

The electric circuit 2 is made of aluminum wiring or the like formed in a predetermined pattern by lift-off, for example, as in the above embodiment. Further, the light emitting element 4 and the light receiving element 5 are also fixed in the concave portion 7 formed at a predetermined position of the substrate 1 as in the above embodiment, and the electrodes of these elements 4 and 5 and the electric circuit 2 are connected by the bonding wire 8. .

If the light emitting element (or the light receiving element) or the communication control element generates a large amount of heat, as shown in FIG.
A heat sink 1 for making a hole 11 in the hole and fixing and supporting a light emitting element 4 and a communication control element (not shown) in the hole 11.
2 should be provided. The heat sink 12 is fixed to the back surface of the substrate 1 with an adhesive or solder 13.

[0014]

As described above, in the optical circuit / electrical circuit mixed board according to the present invention, since each functional element is mounted on the board in a bare chip state, the signal line length can be shortened and the optical circuit can be miniaturized. The upper limit of the signal transmission speed can be expanded. Further, the change of the optical signal wavelength can be easily dealt with by replacing the light emitting element or the light receiving element. Furthermore, since each functional element can be selected in advance, the yield as a product is high,
The cost is low.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an optical circuit / electrical circuit mixed board according to the present invention.

FIG. 2 is a vertical sectional view taken along the line AA of FIG.

3 is a cross-sectional view taken along the line BB of FIG.

FIG. 4 is a cross-sectional view showing another embodiment of the present invention.

FIG. 5 is a vertical sectional view showing still another embodiment of the present invention.

FIG. 6 is a plan view showing still another embodiment of the present invention.

7 is a vertical sectional view taken along the line CC of FIG.

8 is a cross-sectional view taken along the line DD of FIG.

FIG. 9 is a vertical sectional view showing still another embodiment of the present invention.

[Selection diagram]

 1: Semiconductor substrate 2: Electric circuit 3: Optical circuit 4: Light emitting element (or light receiving element) 5: Communication control element 6: Groove 7: Recessed portion 8: Bonding wire 9: Coating layer 11: Hole 12: Heat sink 13: Adhesive Or solder

Claims (2)

[Claims] 1. An optical circuit is formed of an organic material on a substrate on which an electric circuit is formed, and functional elements such as a light emitting element, a light receiving element and a communication control element are mounted in a bare chip state at predetermined positions. Optical circuit / electric circuit mixed board. 2. A coating layer made of an organic material having a low dielectric constant and a refractive index lower than that of the material of the optical circuit is formed on a substrate having an optical circuit formed of the organic material, and the electric circuit is formed on the coating layer. An optical circuit / electrical circuit mixed board, which is formed and mounted with functional elements such as a light emitting element, a light receiving element and a communication control element in a bare chip state at predetermined positions.