JP2001085706A - Optical semiconductor device module - Google Patents

Abstract

(57) [Problem] To eliminate reverse current larger than dark current in an optical semiconductor element and suppress deterioration of response speed of an output electric signal of the optical semiconductor element, suitable for high-speed communication. Things to do. An optical semiconductor element for receiving an optical signal and converting the optical signal into an electrical signal is mounted, and a first conductor pattern for inputting the optical semiconductor element and a second conductor pattern for outputting the optical semiconductor element. An insulating substrate 20 having a substantially rectangular parallelepiped shape having a conductor pattern was provided, and a capacitive coupling portion 15 was provided on the second conductor pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device module used in an optical fiber communication system or the like, which receives light from an optical fiber or the like and converts the light into an electric signal.

[0002]

2. Description of the Related Art A conventional optical semiconductor device module (hereinafter, referred to as "optical semiconductor device module")
An optical module is shown in FIG. FIG. 2A is a plan view of the optical semiconductor element module without a cover, and FIG. 2B is a cross-sectional view taken along line AA in FIG. In FIG. 1, reference numeral 1 denotes a substantially rectangular parallelepiped optical semiconductor element storage package (hereinafter referred to as an optical package), 2 denotes an optical fiber having a light emitting end drawn into the optical package 1, 3 denotes a ceramic or the like, and A substantially rectangular parallelepiped insulating substrate for mounting an optical semiconductor element as a carrier for mounting the element 4 includes a light receiving element (photoelectric conversion element) such as a photodiode, and the light emitting end of the optical fiber 2 faces the light receiving section. 5 is a bonding wire for inputting a drive signal such as a bias voltage to the optical semiconductor element 4 and extracting an output signal, and 6 is a bonding wire formed on the surface of the insulating base 3. A metallizing layer 7 for connection is an electrode pad 9 for extracting an output signal to the outside.
Reference numeral 8 denotes an optical fiber mounting table on which an optical fiber is mounted and fixed in the optical package 1.

FIG. 3 shows another conventional example. FIG. 3A is a plan view of an optical semiconductor device module without a cover, and FIG. 3B is a cross-sectional view taken along line BB of FIG. is there.
As shown in the figure, a via hole 10 is formed inside an insulating substrate 3 for mounting an optical semiconductor element, and the via hole 10 is formed.
Through which the input of the drive signal and the extraction of the output signal are performed. The electrode pad 9 is formed on the inner side surface of the optical package 1, and an output signal is taken out to the outside by a pin connected to the electrode pad 9, a metallization layer (not shown), or the like. One end of the bonding wire 5 is connected to a signal output portion near the light receiving surface of the optical semiconductor element 4, and the other end is connected to the via hole 10. The other configuration is the same as that of FIG. 2, and a configuration similar to that of FIG. 3 is publicly known (see Japanese Patent No. 2638542).

[0004]

However, the above-mentioned conventional optical module has the following problems. The light emitted from the optical fiber 2 is converted into an electric signal by the optical semiconductor element 4, and the electric signal is transmitted to a signal processing circuit or the like outside the optical package 1 through the insulating base 3 for mounting the optical semiconductor element. However, since a reverse bias voltage is applied to the optical semiconductor element 4 even when no optical signal is input, a reverse current due to a minute dark current flows,
This dark current is generated by generating free charges such as free electrons and holes due to heat in the optical semiconductor element 4. This dark current affects the current flowing outside the optical semiconductor element 4,
For example, a part of a bias current and a power supply current of an external signal processing circuit or the like is drawn into the optical semiconductor element 4, and a reverse current larger than a dark current is generated.

[0005] The electric signal converted from the optical signal is first amplified by an amplifier (amplifier) in a signal processing circuit outside the optical package 1. Response speed), and the higher the transmission speed, the greater the effect of minute reverse current. This has been a problem for optical modules for high-speed communication.

Therefore, the present invention has been completed in view of the above circumstances, and an object of the present invention is to eliminate only a dark current by eliminating a reverse current generated in an optical semiconductor device, and to reduce the electric current output from the optical semiconductor device. An object of the present invention is to provide an optical module suitable for high-speed communication by suppressing deterioration of signal response speed.

[0007]

An optical semiconductor element module according to the present invention has an optical semiconductor element mounted thereon and a first conductor pattern for inputting the optical semiconductor element and a second conductor pattern for outputting the optical semiconductor element. An optical semiconductor element module comprising a substantially rectangular parallelepiped insulating base on which a second conductor pattern is formed, wherein a capacitive coupling portion is provided on the second conductor pattern.

According to the present invention, by providing a capacitive coupling portion in the signal transmission path of the second conductor pattern for outputting an electric signal, a part of an external bias current, a power supply current and the like can be partly provided in the optical semiconductor element. To prevent reverse current greater than dark current from being drawn into the optical semiconductor device, and there is only a dark current component in the optical semiconductor device when no light is received. As a result, deterioration of the response speed of the output electric signal of the optical semiconductor device is suppressed. Thus, an optical module optimal for high-speed communication can be obtained.

In the present invention, preferably, an input electrode and an output electrode are formed on a mounting surface of the insulating substrate on which the optical semiconductor element is mounted, and the first conductor pattern is formed on the input electrode and the opposite surface of the mounting surface from the input electrode. And a via conductor connected to the input electrode pad and the input electrode pad, and the second conductor pattern is formed on the output electrode and the opposite surface, and is opposed to the output electrode and has a capacitance. A ground electrode formed of an output electrode pad constituting a coupling portion, and formed so as to surround the input electrode and the output electrode; and an internal ground electrode formed inside the insulating base so as to face the ground electrode. And a second via conductor that connects the second via conductor and the second via conductor.

According to the present invention, electromagnetic shielding (electromagnetic shielding) is achieved by forming a ground potential portion around a capacitive coupling portion and a via conductor for an input electrode, and an external bias current, power supply current, etc. , The occurrence of a reverse current can be further prevented, and only the dark current component can be obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical module according to the present invention will be described below. FIG. 1A is a partial cross-sectional view of an optical semiconductor element and an insulating base part of an optical module according to the present invention, and FIG. 1B is a front view of the insulating base on the side where the optical semiconductor element is mounted. In FIG. 1, reference numeral 1 denotes a substantially rectangular parallelepiped optical package, 2 denotes an optical fiber whose light emitting end is drawn into the optical package 1, 4 denotes a light receiving element (photoelectric conversion element) such as a photodiode, and the like. An optical semiconductor element 5 in which a light emitting end and a light receiving section are opposed to each other, 5 is a bonding wire for extracting an electric signal output from the optical semiconductor element 4, and 8 is an optical fiber mounted in the optical package 1. It is an optical fiber mounting table for mounting and fixing.

An input electrode pad 9a is provided on the surface of the insulating substrate 20 opposite to the surface on which the optical semiconductor element 4 is mounted, and an input electrode pad 9b is formed on the opposite surface to face the output electrode 9b. The output electrode pad 10 which forms a capacitive coupling portion is a via conductor connecting the input electrode 13 and the input electrode pad 9a, and 11 is an internal ground formed inside the insulating base 20 so as to face the ground electrode 12. Electrodes 13 are input electrodes for inputting drive signals such as bias voltage and formed on the mounting surface of the optical semiconductor element 4, 14 are output electrodes for outputting an electric signal from the optical semiconductor element 4, and 15 are outputs The capacitive coupling portion 20 formed by the electrode 14 and the output electrode pad 9b opposed thereto is made of a ceramic substrate or the like laminated in multiple layers, and is a substantially rectangular parallelepiped insulating base.

[0013] insulating substrate of the present invention 20, the transmission information amount of the optical signal is in a high-speed transmission speed range gigabit (10 ⁹ bit) order, it is preferable to be small dielectric loss materials, ceramics, glass ceramics, glasses organic Resin-based composite materials are preferred. Specifically, alumina (A
l ₂ O ₃ ) ceramics, aluminum nitride (AlN)
Ceramics, silicon nitride (Si ₃ N ₄ ) ceramics and the like. To reduce the high-frequency transmission loss, the bonding wire 5, the input electrode pad 9a, the output electrode pad 9b, the internal ground electrode 11, the ground electrode 12, the input electrode 13, the output electrode 14, the via conductor 10, the second As conductors for signal transmission lines, such as via conductors 10a, Ag, Cu,
Those having a low electric resistance such as Au, Al and alloys containing these as a main component are preferable.

In the present embodiment, the first conductor pattern forming the drive signal input path includes the input electrode 13 and the via conductors 10 penetrating therethrough and connected to the input electrode pad 9a through the surface opposite to the mounting surface. The second conductor pattern, which is composed of the input electrode pad 9a and forms an electric signal output path, is formed on the opposite surface to the output electrode 14 and the output electrode 1
4 and an output electrode pad 9b that constitutes the capacitive coupling portion 15 in opposition.

The input electrode 1 on the mounting surface of the insulating substrate 20
A ground electrode 12 is formed so as to surround the periphery of the third electrode 3 and the output electrode 14, and a plurality of second via conductors 10 a connecting the ground electrode 12 and the internal ground electrode 11 inside the insulating base 20 are parallel to the via conductor 10. Formed. In this case, as shown in FIG. 1A, the second via conductor 10a is formed around the via conductor 10 and the capacitive coupling portion 15 along a cylindrical surface around the via conductor 10 and the capacitive coupling portion 15 as a central axis. Preferably, they are provided symmetrically. In addition, the length of the second via conductor 10a is preferably １ ／ ± 0.1 mm of the thickness of the insulating base 20 (the distance between the mounting surface of the optical semiconductor element 4 and the opposite surface). If the distance is out of the range, the electromagnetic field is disturbed and coupling loss of the capacitive coupling portion 15 occurs.

The interior ground electrode 11 inside the insulating base 20 is
A gap 11a is formed so as not to obstruct the via conductor 10 and the capacitive coupling portion 15. The size of the gap 11a is suitable for high-speed transmission while not obstructing capacitive coupling (electromagnetic coupling) of the capacitive coupling portion 15. It depends on the bit rate of the high transmission rate, but one side in the vertical and horizontal directions is 1.0 to 3.0.
It is preferable that the hole be a square hole of mm. If it is less than 1.0 mm, disturbance of the electromagnetic field occurs and coupling loss of the capacitive coupling portion 15 occurs. If it exceeds 3.0 mm, the coupling loss similarly occurs.

The height of the gap 11a from the bottom surface of the optical package is preferably 0.3 mm or more. If it is less than 0.3 mm, disturbance of the electromagnetic field occurs and coupling loss of the capacitive coupling portion 15 occurs.

The insulating substrate 20 according to the present invention comprises an input electrode pad 9a and an output electrode pad 9 provided on the insulating substrate 20.
b is connected to an electrode pad (not shown) corresponding to the input electrode pad 9a and the output electrode pad 9b provided on the inner side surface of the optical package by soldering or the like, thereby being installed in the optical package.

In the above embodiment, the light emitting end of the optical fiber 2 is drawn into the optical package. However, the present invention is not limited to such a structure. And a cap provided with a condenser lens such as a spherical lens is brazed on the metallizing layer for sealing, and a metal terminal is provided on each of the input electrode pad 9a and the output electrode pad 9b opposite to the mounting surface. It can be brazed and can be a can type package. In this case, there is no need to mount the optical fiber 2 in the package.

Thus, the present invention eliminates a part of an external bias current, a power supply current, or the like flowing into the optical semiconductor element to generate a reverse current larger than the dark current. Since only the dark current component exists in the optical module, deterioration of the response speed of the output electric signal of the optical semiconductor element can be suppressed, and an optical module optimal for high-speed communication can be obtained.

It should be noted that the present invention is not limited to the above embodiment, and various changes may be made without departing from the scope of the present invention.

[0022]

According to the present invention, the provision of the capacitive coupling portion in the second conductor pattern for the electric signal output path allows a part of the external bias current, power supply current, etc. to flow into the optical semiconductor device and cause darkness. This eliminates the occurrence of a reverse current larger than the current, and as a result, when no light is received, only a dark current component exists in the optical semiconductor element, thereby suppressing the deterioration of the response speed of the output electric signal of the optical semiconductor element. Thus, the optical module suitable for high-speed communication can be configured.

[Brief description of the drawings]

1A and 1B show an optical module of the present invention, wherein FIG. 1A is a partial cross-sectional view of an optical semiconductor element and an insulating base, and FIG. 1B is a front view of a mounting surface side of the insulating base.

2A and 2B show a conventional optical module, wherein FIG. 2A is a plan view of the optical module without a cover, and FIG. 2B is a cross-sectional view taken along line AA of FIG.

3A and 3B show another conventional optical module, in which FIG. 3A is a plan view of the optical module without a cover, and FIG.
It is sectional drawing in the B line.

[Explanation of symbols]

 1: optical package 2: optical fiber 4: optical semiconductor element 5: bonding wire 9a: input electrode pad 9b: output electrode pad 10: via conductor 10a: second via conductor 11, 12: ground electrode 13: input electrode 14: output electrode 15: capacitive coupling part 20: insulating base

Claims (2)

[Claims] 1. A substantially rectangular parallelepiped insulating base on which an optical semiconductor element is mounted and on which a first conductor pattern for inputting the optical semiconductor element and a second conductor pattern for outputting the optical semiconductor element are formed. An optical semiconductor element module comprising: the second conductor pattern provided with a capacitive coupling portion. 2. An input electrode and an output electrode are formed on a surface of the insulating substrate on which the optical semiconductor element is mounted, and the first conductor pattern penetrates the input electrode and an opposite side of the mounting surface from the input electrode so that an input is formed. The second conductor pattern is formed on the opposite surface to the output electrode and faces the output electrode to form a capacitive coupling portion. A second electrode connecting the ground electrode formed of the output electrode pad and surrounding the input electrode and the output electrode, and an internal ground electrode formed inside the insulating base so as to face the ground electrode. 2. The optical semiconductor element module according to claim 1, wherein said via conductor is provided.