JP2002299743A - Board, for mounting optical-component and optical module using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical-component mounting board and an optical module where the transmission of high-frequency signal, having a transmission speed nearly equal to 10 Gbps or not lower than 10 Gbps, is made possible, and its high-frequency transmission characteristic will not become unstable due to its impedance mismatching being generated, in contact with its package. SOLUTION: The optical-component mounting board B has a first wiring board 10 and a second wiring board. With respect to the first wiring board 10, an inclined surface 12a is formed in its end portion for providing therein an optical semiconductor element 5a to form in the inclined surface 12a wirings for thereby applying currents to the optical semiconductor element 5a. With respect to the second wiring board, in the end portion of the second wiring board an inclined surface 12b is formed for joining it to the inclined surface 12a of the first wiring board 10 to form in the inclined surface 12b, and in its rear surface connected with the inclined surface 12b wirings 9c for applying thereby the currents to the optical semiconductor element 5a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical component mounting board used for optical transmission such as optical fiber communication and optical interconnection, and an optical module using the same.

[0002]

2. Description of the Related Art In recent years, there has been a demand for an optical communication system having a large capacity and multifunctionality. And
For the purpose of reducing the cost of assembling an optical module, a technique of mounting optical components of an optical semiconductor element such as an optical fiber, a semiconductor laser, or a photodiode on the same substrate, that is, a so-called optical hybrid mounting technique, has attracted attention. According to this technology, it is possible to obtain a coupling between an optical semiconductor element and a lens or an optical fiber without alignment by simply mounting the optical fiber and the optical semiconductor element on a groove or electrical wiring formed on the same substrate. Becomes

An optical component mounting board, which is a key part for realizing the above technology, is usually provided with a groove for mounting an optical fiber, a ball lens, and the like, and for mounting an optical semiconductor element such as a semiconductor laser and a light receiving element. Electrical wiring and solder are formed with high precision. Note that, in order to realize high precision, generally, a Si substrate is used as an optical component mounting substrate, and grooves are formed by anisotropic etching using KOH or the like.

FIG. 5 shows an example of a conventional optical component mounting board. A groove 1 for mounting a ball lens 6, a solder 2 for mounting a semiconductor laser 5a, a signal line 3a or a ground line 3b formed of a metal thin film, and a light receiving element 5b are mounted on the optical component mounting board A. A groove 4 (hereinafter, referred to as a light-receiving element carrier mounting groove) for mounting the light-receiving element carrier 7 is formed.

Usually, such an optical component mounting board A is mounted in a package as shown in FIG. 6, and electrically connected to the wirings 3c and 3d in the package by wire bonding 8 or tape bonding. Thus, an optical module A1 is configured.

[0006] However, recently, the capacity of optical transmission has been further increased, and 10 Gb
High-frequency signal transmission such as ps and 40 Gbps is required,
Eventually, an optical component mounting board is also required to be suitable for high-frequency signal transmission.

Therefore, in the above-described embodiment, impedance mismatch due to the wire bond 8 occurs in the connection between the electric lines 3a and 3b on the optical component mounting board A and the electric lines 3c and 3d on the package, and the electric Interference due to signal reflection occurs, which causes unstable high frequency characteristics.

Further, a groove 1 for mounting a ball lens 6 and a light receiving element carrier mounting groove 4 are provided in the vicinity of the semiconductor laser 5a, and since there is no space, a coplanar line suitable for high-frequency signal transmission. Is difficult to form.

Also, the signal lines 3a of the optical component mounting board,
It is necessary to make the height of the surface having the ground line 3b and the surface of the package having the signal line 3c and the ground line 3d the same. Conventionally, the package becomes unnecessarily thick by the thickness of the optical component mounting board. I was Normally, the package uses a ceramic multilayer board and has vias connecting the wiring in the vertical direction. However, if the package is thicker, the length of the via becomes longer and impedance mismatch is likely to occur. There is.

As described in JP-A-2000-199831, a groove is formed on the front and back surfaces of the substrate by anisotropic etching of a Si substrate, a metal layer is formed on a slope, and bonding is performed with a solder ball. Also, a configuration that takes a contact has been proposed, but such a configuration has not been put into practical use due to a problem such as occurrence of impedance mismatch in connection using a solder ball.

That is, a high-frequency signal of about 10 Gbps or higher can be transmitted, and a high-frequency signal transmission characteristic is not unstable due to impedance mismatch at the contact with the package. Modules are desired.

[0012]

In order to solve the above-mentioned problems,
An optical component mounting substrate according to the present invention has a first configuration in which an inclined surface is formed at one end of a substrate on which an optical semiconductor element is provided, and a wiring for energizing the optical semiconductor element is formed on the inclined surface. A second wiring board having an inclined surface formed at one end thereof to be joined to the inclined surface of the first wiring substrate, and a wiring for energizing the optical semiconductor element formed on the inclined surface and a lower surface connected to the inclined surface; And a wiring board.

Thus, the electrical contact can be obtained only by arranging the optical component mounting board in the package without connecting the line in the optical component mounting board to the line in the package by wire bonding.

Further, since the electric line is formed on the back surface of the substrate, it is possible to form a coplanar line suitable for high-frequency signal transmission without being affected by the light receiving element carrier mounting groove located behind the semiconductor laser. Become.

Further, since the electric line is formed on the back surface of the substrate, the thickness of the package can be reduced by the thickness of the substrate, and impedance mismatch due to vias can be reduced.

That is, according to the present invention, it is possible to provide an optical component mounting board suitable for high-frequency transmission, and to provide an optical module having excellent high-frequency characteristics.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings schematically shown.

As shown in FIG. 1, a groove 1 for mounting a ball lens 6, a solder 2 for mounting a semiconductor laser 5a on a main surface of a first wiring board 10 made of Si single crystal or the like, It is assumed that a coplanar line 9a and the like are formed. Further, it is assumed that a coplanar line 9c for obtaining a contact with the package is formed on the second wiring substrate 11. The optical component mounting board B has at least these 2
The coplanar line 9a on the front surface of the Si substrate and the coplanar line 9c on the back surface are formed by the slope 12a of the first wiring board 10 and the slope 12a of the second wiring board 11.
It is assumed that they are joined via b.

As described above, the optical component mounting board B is provided with the inclined surface 12
a, and the optical semiconductor element 5 is formed on the inclined surface 12a.
a wiring substrate 1 formed with a wiring for supplying a current to a
0, an inclined surface 12b to be joined to the inclined surface 12a of the first wiring board 10 is formed at one end, and the inclined surface 12b and the inclined surface 1
And a second wiring substrate 11 having a wiring 9c for supplying electricity to the optical semiconductor element 5a formed on the lower surface connected to the second wiring board 2b.

The wiring boards may be joined by any of solder joining, joining using a conductive adhesive, and direct joining. Here, the width and depth of the groove 1 are precisely manufactured, and the groove 1, the electric wiring 9a for mounting the semiconductor laser 5a, and the solder 2 are accurately positioned, and optical coupling by passive alignment is performed. Is possible.

The groove 1 and the slope 12a are formed by anisotropic etching using an aqueous alkali solution such as KOH. The solder 2 and the coplanar lines 9a and 9c are formed by vapor deposition, film formation such as sputtering, lift-off or etching. This enables highly accurate groove and pattern formation.

The first wiring substrate 10 is made of single-crystal Si.
(The main surface is a {100} plane with a Miller index.) For the second wiring board 11, similar single crystal Si or ceramics such as Al 2 O 3 is used. Considering the formation of the slope 12b and the formation of the coplanar line 9c, the single crystal Si is preferable. Thus, the angles and widths of the slope 12a and the slope 12b are exactly the same, so that the coplanar lines 9a and 9c can be easily positioned.

The semiconductor laser 5 is mounted on the optical component mounting board.
When the light receiving element 5b for modulating the optical signal a is mounted, the light receiving element carrier 7 may be mounted, but as shown in the optical component mounting board C of FIG. Function may be provided. Further, also in this case, when the single wiring Si is used for the second wiring substrate 11 and the slope 12c is formed by anisotropic etching, the angle of the slope 12c can be accurately formed, and the coplanar line 9a, In addition to the positioning of 9d, the position of the light receiving element carrier 7 becomes accurate, and thus the light of the semiconductor laser 5a can be easily received.

In FIG. 2, since there is no need for high-speed signal wiring for the light receiving element 5b, wire bonding is applied to the wiring in the package. However, the signal lines and ground lines of the light receiving element are also inclined. It may be electrically connected to the wiring of the package via 12b.

Hereinafter, an optical module using the optical component mounting board of the present invention will be described with reference to FIGS.

The optical module B1 comprises an optical component mounting substrate B made of Si single crystal which can be anisotropically etched, a package 13 made of ceramic having an electric line 9b, an optical isolator 14 for blocking return light, a semiconductor. Laser 5
a light-receiving element carrier 7 having a light-receiving element 5b for modulating a, a driver IC 15 for driving the semiconductor laser 5a, and condensing light on an optical fiber 17.
GRIN Lens (Graded Index Len)
s) It is composed of 16 and the like.

It is assumed that at least optical semiconductor elements and optical components such as the semiconductor laser 5a and the ball lens 6 are mounted on the optical component mounting board B. As shown in FIG. 4, the light receiving element carrier 7 may be mounted on the optical component mounting board C to form an optical module C1.

The optical component mounting boards B and C and the package 1
3 denotes coplanar lines 9c and 9b formed respectively.
Are electrically connected to each other. Note that the bonding may be performed by using any of soldering, bonding using a conductive adhesive, direct bonding, and the like. Thus, electrical bonding can be performed without wire bonding between the optical component mounting boards B and C and the package 13. The coplanar line 9 in the package 13
b is the driving driver I arranged in the package 13
C15.

The collimated light emitted from the ball lenses 6 on the optical component mounting boards B and C passes through the optical isolator 14 and is condensed by the GRIN lens 16 and the like, and is incident on the optical fiber 17.

With the optical component mounting board manufactured in this way, electrical connection can be obtained without causing impedance mismatch in connection between the optical component mounting board and the package. Also, a coplanar line suitable for high-frequency signal transmission can be easily formed. Further, by using such an optical component mounting substrate, it is possible to manufacture an optical module having excellent high-frequency characteristics and emitting stable light.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a first wiring substrate 10, a substrate of a single crystal of Si (main surface is {100} plane) (resistivity of 5000Ω or more) was used. A groove 1 for mounting a ball lens and a slope 12a were formed on the surface of the substrate. Groove 1, slope 12a
Was manufactured by anisotropic etching using a KOH aqueous solution.

Next, after forming an oxide film (SiO 2) to a thickness of 1 μm on the Si substrate by thermal oxidation, a solder 2 for mounting a semiconductor laser and a coplanar line 9 a were prepared.
In the coplanar line 9a, Ti / Pt / Au (lower layer / middle layer / upper layer) was formed to a thickness of 0.8 μm, and for the solder 2, an AuSn alloy solder was formed to a thickness of 3 μm. The pattern was formed using a lift-off technique, through steps of resist coating, vapor deposition, and resist stripping. The resistance of the coplanar line 9a is designed to be 50Ω, and the line width of the ground is 60Ω.
0 μm, signal line width 100 μm, line spacing 50 μm
And

Next, a second wiring board 11 was manufactured. The second wiring wiring substrate 11 has a single crystal Si {100}
A substrate was used. The slope 12b of the second wiring board 11 was formed by anisotropic etching using KOH. After forming an oxide film (SiO2) on the substrate, a coplanar line 9c was formed on the slope 12b. In addition, slope 1
The coplanar line 9c of 2b was formed of Ti / Pt / Au to a thickness of 0.8 μm by a lift-off method, similarly to the first wiring wiring board 10.

Next, after aligning the positions of the coplanar lines of the first wiring wiring board 10 and the second wiring wiring board 11, Au was directly bonded to each other while applying ultrasonic waves.

The optical component mounting board B thus formed
The semiconductor laser 5a and the ball lens 6 were mounted thereon, and the optical component mounting board B, the optical isolator 14, the drive driver IC 15, and the GRIN lens 16 were mounted in the package. Thereafter, the position of the optical fiber 17 was determined by active alignment, and the optical fiber was fixed by YAG.

For this optical module, a signal is input by a pulse pattern generator, and the signal is input by an oscilloscope.
Response characteristics were measured. As a result, a good eye pattern was obtained for a 10 Gbps transmission signal.

[0037]

According to the present invention, there is provided a semiconductor device in which an optical semiconductor element is provided with an inclined surface at one end thereof, and a wiring for supplying a current to the optical semiconductor element is formed on the inclined surface. A first wiring board, and an inclined surface formed at one end portion to be joined to the inclined surface of the first wiring substrate, and a wiring for supplying electricity to the optical semiconductor element is formed on the inclined surface and a lower surface connected to the inclined surface. And two wiring boards.
Thus, an electrical contact can be obtained only by arranging the optical component mounting substrate in the package without connecting the line in the optical component mounting substrate to the line in the package by wire bonding.

Further, since the wiring is formed on the back surface of the second wiring substrate, the coplanar line suitable for high-frequency signal transmission can be provided without concern for the light receiving element carrier mounting groove located behind the optical semiconductor laser. It can be formed.

Further, the thickness of the package can be reduced by the thickness of the substrate, and the impedance mismatch due to vias can be reduced.
It is possible to supply an optical component mounting board excellent in high frequency characteristics such as ps.

Further, by using a single-crystal Si {100} substrate for the first wiring substrate 1 and the second wiring substrate, it is possible to accurately position the coplanar lines formed on both. Further, in this case, even when the light receiving element carrier is mounted on the optical component mounting board, the positioning of the light receiving element carrier can be easily performed, and the optical coupling can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an embodiment of an optical component mounting board according to the present invention, wherein (a) and (b) are perspective views, respectively, and (c) is a plan view.

FIG. 2 is a diagram schematically illustrating another embodiment of the optical component mounting board according to the present invention, and (a) and (b) are perspective views, respectively. 1 shows an example of an optical component mounting board according to the present invention.

FIG. 3 is a perspective view schematically showing one embodiment of the optical module according to the present invention.

FIG. 4 is a perspective view schematically showing another embodiment of the optical module according to the present invention.

FIGS. 5A and 5B are perspective views each showing an example of a conventional optical component mounting board.

FIG. 6 is a perspective view of a conventional optical module.

[Explanation of symbols]

 1: Optical fiber, ball lens mounting groove 2: Solder 3a: Signal line (optical component mounting board side) 3b: Ground wire (optical component mounting board side) 3c: Signal wire (package side) 3d: Ground wire (package side) 4: light receiving element carrier mounting groove 5: optical semiconductor element 5a: semiconductor laser 5b: light receiving element 6: ball lens 7: light receiving element carrier 8: wire bonding 9a: coplanar line (upper surface of optical component mounting substrate) 9b: coplanar line (package) 9c: Coplanar line (lower surface of optical component mounting substrate) 9d: Coplanar line (light receiving element carrier) 10: First wiring substrate 11: Second wiring substrate 12a, 12b, 12c: Slope 13: Package (substrate) 14: Isolator 15: Driver IC 16: GRIN lens 17: Optical fiber

Claims (3)

[Claims] A first wiring board formed by forming an inclined surface at one end of a substrate on which the optical semiconductor element is provided, and forming a wiring for supplying electricity to the optical semiconductor element on the inclined surface; And a second wiring board formed with an inclined surface to be joined to the inclined surface of the first wiring substrate, and a second wiring substrate formed on a lower surface connected to the inclined surface with a wiring for supplying electricity to the optical semiconductor element. An optical component mounting substrate, comprising: 2. The optical semiconductor device according to claim 1, wherein the optical semiconductor device is a light emitting device, and a light receiving device for monitoring light emitted from the light emitting device is provided on the second wiring board.
An optical component mounting substrate according to claim 1. 3. An optical module comprising: a substrate for mounting the optical component according to claim 1; and an optical waveguide to be optically connected to the optical semiconductor element.