JPH0983083A - Semiconductor module - Google Patents

Abstract

(57) Abstract: In a semiconductor laser module or a semiconductor modulator module in which a laser oscillator and a modulator are integrated on the same chip, a return loss for a modulation signal up to about 10 GHz is reduced and deterioration of an optical waveform is suppressed. An object is to provide a semiconductor module that can be avoided. A semiconductor laser chip 1 and a lead 8a to which a modulated microwave signal is applied from an external driver IC.
A T-type attenuator composed of three resistors is interposed in the strip line 6 provided between the modulation signal input electrode and the modulation signal input electrode. This attenuator improves the electrical matching with the external driver IC and can reduce the return loss.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor module containing at least a modulator and used for optical communication or the like, and particularly suitable for a semiconductor laser module in which a laser oscillator and a modulator are integrated on the same chip. Semiconductor module.

[0002]

2. Description of the Related Art FIG. 12 is a schematic view showing a conventional semiconductor laser module used for optical communication. The semiconductor laser chip 21 is mounted on the carrier 22, and the semiconductor laser chip 21 has a laser oscillator and a modulator integrated therein. As shown in FIG. 13, this chip 21 is provided with a modulation signal input electrode 21a and a laser oscillation power electrode 21b on the upper surface side, and a grounding electrode 21c on the lower surface side of the chip.

Further, the carrier 22 is shown in FIG.
As shown in the sectional view and the top view in (b), a conductive CuW layer 22a, an insulating AlN layer 22b formed on the CuW layer 22a, and a conductive layer formed on the AlN layer 22b. And a layer 22c. As shown in FIG. 14B, the conductive layer 22c has a ground pattern 22f, an intermediate pattern 22g, and an intermediate pattern 22g.
Resistance R of 50Ω connecting between the ground and the ground pattern 22f
Are provided. The broken line S indicates the chip bonding position.

On the other hand, on one side of the carrier 22, CuW is used.
The layer 22a projects laterally beyond the AlN layer 22b to form a step. Via holes 22e are selectively formed in the AlN layer 22b, and the CuW layer 22a and the ground pattern 22f are formed through these via holes 22e.
And are electrically connected. The carrier 22 is mounted on a Peltier cooler 23, and the Peltier cooler 23 is fixed to the bottom of a metal storage case 24. When a predetermined current is passed through the Peltier cooler 23 via a lead (not shown), heat is absorbed on the upper side of the Peltier cooler 23, and the semiconductor laser chip 21 on the carrier 22 can be cooled. Further, at this time, heat corresponding to the absorbed heat is generated on the lower side of the Peltier cooler 23, but this heat is radiated to the outside via the storage case 24.

A grounding plate 27 and a strip line 25 are provided on one side wall of the storage case 24 so as to penetrate the wall of the storage case 24 in a superposed state. FIG.
5A and 5B are a top view and a sectional view showing the strip line 25. The strip line 25 includes a plate-shaped ceramic portion 25a and the ceramic portion 25a.
A strip conductor 25b linearly extending in the widthwise center on the upper surface side, and a conductive grounding portion 25c that covers the vicinity of both end portions on the upper surface side of the ceramic portion 25a, both side surfaces and the bottom surface.
It is composed of The lead 28a is joined to the strip conductor 25b at the outer portion of the storage case 24. The strip line 25 is set to have the same characteristic impedance as the internal impedance of the semiconductor laser chip 21. In addition, an insulating material 29 is provided on a portion of the storage case 24 where the strip line 25 penetrates.
a is provided so that the strip conductor 25b and the storage case 24 are electrically separated from each other. Furthermore,
The ground portion 25c of the strip line 25 is connected to the ground plate 27.
Is electrically connected to the storage case 24 via.

A lead 28b is provided penetrating the other side wall of the storage case 24. This storage case 24
An insulating material 28b is provided in a portion where the lead 28b penetrates so as to electrically separate the lead 28b and the storage case 24. In addition, the strip conductor 25b of the strip line 25 and the electrode 2 on the chip 21
1a, the electrode 21a and the intermediate pattern 22g connected to the resistor R, and the electrode 21b of the chip 21 and the lead 28b are electrically connected by a thin metal wire (bonding wire) 30, respectively. .

In the semiconductor laser module thus constructed, the housing case 24 is set to the ground potential, the laser oscillation power is supplied to the semiconductor laser chip 21 via the lead 28b, and the lead 28a is connected from the external driver IC. When a modulation signal is supplied to the modulator in the chip 21 via the semiconductor laser chip 21, the modulated laser light is output.

[0008]

However, the above-mentioned conventional semiconductor laser module has the following problems. That is, in recent years, as a semiconductor laser module for optical communication, a module that performs high-speed modulation with a bit rate of about 10 Gb / s has been receiving attention. In this case, in the conventional semiconductor laser module, the Sll characteristic (return loss) is improved simply by using the strip line having the same characteristic impedance as the internal impedance of the semiconductor laser chip. When a high frequency signal is input, there is a problem that the return loss is large and the optical waveform is deteriorated.

The present invention has been made in view of the above problems of the conventional example, and provides a semiconductor laser module capable of reducing the return loss for a high frequency signal up to about 10 GHz and avoiding the deterioration of the optical waveform. That is the purpose.

[0010]

SUMMARY OF THE INVENTION The above-mentioned problems are solved by accommodating at least a modulator, a semiconductor chip having a modulation signal input electrode, a carrier on which the semiconductor chip is mounted, and the carrier together with the semiconductor chip. A housing case, a lead to which a modulation signal is applied from the outside, a modulation signal transmission line electrically connecting the lead and the modulation signal input electrode, and an attenuator provided in the modulation signal transmission line. This is solved by a semiconductor module characterized by having.

In the present invention, an attenuator is provided in the modulation signal transmission line that electrically connects the lead and the modulation signal input electrode of the semiconductor chip, and this attenuator allows connection with an external driver IC. Improve electrical matching. Thereby, the return loss can be remarkably reduced, and the return loss can be suppressed to −20 dB or less for a high frequency signal of 10 GHz, for example.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a schematic view showing a first embodiment of a semiconductor laser module according to the present invention.

The semiconductor laser chip 1 is mounted on a carrier 2, and the carrier 2 is mounted on a Peltier cooler 3 and housed in a metal housing case 4. A laser oscillator and a modulator are integrated in the semiconductor laser chip 1, and as shown in FIG. 2, a modulation signal input electrode 1 a to which a high frequency modulation signal is input and a laser oscillation voltage are provided on the upper surface side of the chip 1. An electrode 1b to be applied is provided, and a grounding electrode 1c is provided on the lower surface side of the chip 1.

The carrier 2 has a conductive CuW layer 2a and an insulating Al layer formed on the CuW layer 2a, as shown in the sectional view and the top view of FIGS. 3 (a) and 3 (b), respectively.
N layer 2b and conductive layer 2 formed on this AlN layer 2b
and c. On one side of the carrier 2, the CuW layer 2a projects laterally beyond the AlN layer 2b to form a step. Further, the conductive layer 2c is provided with a ground pattern 2f, an intermediate pattern 2g, and a resistance R of 50Ω that connects the intermediate pattern 2g and the ground pattern 2f. Further, a plurality of via holes 2e are selectively formed in the AlN layer 2b, and the CuW layer 2a and the ground pattern 2f are electrically connected via these via holes 2e. In FIG. 3A, the broken line S indicates the chip bonding position.

The carrier 2 is mounted on a Peltier cooler 3, which is fixed to the bottom of the storage case 4. When a predetermined current is supplied to this Peltier cooler 3 via a lead (not shown), heat is absorbed on the upper side of the Peltier cooler 3, and the carrier 2
The upper semiconductor laser chip 1 can be cooled. At this time, heat corresponding to the absorbed heat is generated on the lower side of the Peltier cooler 3, but this heat is radiated to the outside via the storage case 4.

A first strip line 5 and a ground plate 7 are arranged on one side wall of the storage case 2 so as to pass through the wall of the storage case 4 in a superposed state. As shown in FIG. 4, the first stripline 5 includes a plate-shaped ceramic portion 5a, a strip conductor 5b linearly extending in the widthwise center of the upper surface side of the ceramic portion 5a,
The ceramics portion 5a is constituted by a conductive grounding portion 5c which covers both sides of the upper surface, the side surface and the lower surface.
The strip conductor 5b is connected to the lead 8a at the outer portion of the storage case 4. Further, an insulating material 9a is provided in a portion of the storage case 4 that the first strip line 5 penetrates, so that the strip conductor 5b and the storage case 4 are electrically separated.

The ground plate 7 extends slightly inside the storage case 4 from the strip line 5, and a second strip line 6 is bridged between the ground plate 7 and the stepped portion of the carrier 2. . This second stripline 6
As shown in FIG. 5, a plate-shaped dielectric 6a, a strip conductor 6b linearly extending in the center of the upper surface of the dielectric 6a, an attenuator 6d interposed in the strip conductor 6b, The body 6a is configured by a conductive grounding portion 6c that covers both sides of the upper surface, the side surface, and the lower surface.
The attenuator 6d includes two resistors R11 and R12 connected in series in the middle of the strip conductor 6b.
It is composed of a resistor R13 connected between the resistors R11 and R12 and the ground portion 6c.

A lead 8b is provided on the other side of the storage case 4 so as to penetrate the wall of the storage case 4. An insulating material 9b is provided in a portion of the storage case 4 through which the lead 8b penetrates, so that the lead 8b and the storage case 4 are electrically separated. And the first
Between the strip conductor 5b of the strip line 5 and the strip conductor 6b of the second strip line 6, between the strip conductor 6b of the second strip line 6 and the electrode 1a of the chip 1, and the resistance of the electrode 1a and the carrier 2 Between the intermediate pattern 2g connected to R and between the electrode 1b and the lead 8b
Between and is a thin metal wire (bonding wire) 10
Are electrically connected to each other. Further, the ground portions 5c, 6c of the first and second strip lines 5, 6 are electrically connected to the storage case 4 via the ground plate 7.

In the semiconductor laser module according to this embodiment having such a configuration, the housing case 4 is set to the ground potential, the laser oscillation power is supplied to the semiconductor laser chip 1 via the lead 8b, and the semiconductor laser chip 1 is externally attached to the lead 8a. When a modulated microwave signal is input from the driver IC of
The laser light output from the laser oscillator of the semiconductor laser chip 1 is modulated by the modulator and emitted to the outside. At this time, heat is generated in the semiconductor laser chip 1 due to generation of laser light, but the semiconductor laser chip 1 is cooled by the Peltier cooler 3.

In the present embodiment, the second strip line 6 is provided with the attenuator 6d and the lead 8a.
Since the modulation signal input to is given to the chip 1 through the attenuator 6d, the electrical matching with the external driver IC can be improved, and as a result,
The return loss of the modulated microwave signal can be reduced.

The performance of the semiconductor laser module according to this embodiment will be described below in comparison with a conventional example. The resistors R11 and R12 shown in FIG. 5 are both 16.6Ω and the resistor R13 is 66.7.
When Ω is set, the attenuation rate becomes an attenuator of 6 dB, and the return loss (loss in round trip) can be improved by 12 dB. 6 (a) and 6 (b), the horizontal axis represents frequency,
FIG. 6 is a diagram showing return loss in the conventional semiconductor laser module and the semiconductor laser module of the present embodiment (present invention), with the return loss taken on the vertical axis. This figure 6
As shown in (a) and (b), in the conventional semiconductor laser module, the return loss is about -10 dB when the frequency is about 10 GHz, whereas in the present embodiment, the return loss is -20 dB. It can be: Therefore, in the present embodiment, there is an effect that the deterioration of the optical waveform can be avoided even when the bit rate is high, such as 10 Gb / s.

(Second Embodiment) FIG. 7 is a schematic view showing a second embodiment of the present invention, and FIG. 8 is a strip line 15 thereof.
FIG. In FIG. 7, the same components as those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment, the ground plate 7 and the strip line 15 are arranged so as to pass through the side wall of the storage case 4 in a superposed state, and the tip end of the strip line 15 is arranged on the stepped portion of the carrier 2. ing. As shown in FIG. 8, the strip line 15 has a plate-shaped ceramic portion 1
5a, a strip conductor 15b linearly extending in the widthwise center of the upper surface of the ceramic portion 15a, and an attenuator 15 interposed in the middle of the strip conductor 15b.
d, and a grounding portion 15c made of a conductor that covers the vicinity of both sides of the upper surface of the ceramic portion 15a, the side surface, and the bottom surface. The attenuator 15d includes resistors R21 and R22 that are connected in series between the strip conductors 15a and are interposed between the resistors R21 and R22 and the ground portion 15.
It is composed of a resistor R23 which is connected to c.

Also in this embodiment, the strip line 15
Is provided with an attenuator 15d, and the modulated microwave signal is given to the semiconductor laser chip 1 via this attenuator 15d, so that the electrical matching with the external driver IC can be improved, and the first The same effect as the form can be obtained. (Third Embodiment) FIG. 9 is a schematic view showing a third embodiment of the present invention, and FIG. 10 is a top view showing the carrier 12 thereof. In FIG. 9, the same parts as those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. Further, in FIG. 10, the broken line shows the mounting position of the chip 1.

In the present embodiment, an attenuator 12d is formed on the conductor layer 12c of the carrier 12 together with the ground pattern 12f and the intermediate connection pattern 12g. This attenuator 12d, as shown in FIG.
Three resistors R31, R32, R33 and these resistors R31, R
The resistor R31 and R32 are connected in series, and the resistor R33 is connected between the resistors R31 and R32 and the ground pattern 12f.

On the other hand, the strip line 25 is basically the same as that shown in FIG. Between the strip conductor of the strip line 25 and the input end of the attenuator 12d, between the output end of the attenuator 12d and the chip 1
Of the modulation signal input electrode 1a, between the electrode 1a and the intermediate pattern 2g connected to the resistor R, and between the laser oscillation power input electrode 1b of the chip 1 and the lead 8b. It is electrically connected.

Also in this embodiment, the modulation microwave signal is applied to the modulation signal input electrode of the chip 1 through the attenuator 12d provided on the carrier 12, so that the electrical matching with the external driver IC is improved. You can Thereby, the same effect as that of the first embodiment can be obtained. In each of the above-described embodiments, the case where the attenuator is a T-type attenuator composed of three resistors R1, R2, and R3 as shown in the circuit diagram of FIG. 11A has been described. Therefore, the attenuator usable in the present invention is not limited to the T type, and is composed of three resistors R1, R2 and R3 as shown in the circuit diagram of FIG. Attenuators of other shapes such as a π-type attenuator may be used. Further, in the above-described embodiment, the semiconductor module having the semiconductor chip in which the laser oscillator and the modulator are integrated on the same chip has been described. The present invention is applicable to a semiconductor module having a semiconductor chip including only a modulator. Can also be applied.

[0027]

As described above, according to the present invention,
An attenuator is provided between the lead to which the modulation signal is input and the modulation signal input electrode of the semiconductor chip. This attenuator improves the electrical matching with the external driver IC, thus significantly reducing the return loss. can do. For example, according to the present invention, the return loss is −20 for a high frequency signal having a frequency of 10 GHz.
The effect is that it can be suppressed to dB or less, and deterioration of the optical waveform in high-speed modulation can be avoided.

[Brief description of drawings]

FIG. 1 is a schematic view showing a first mode of a semiconductor laser module of the present invention.

FIG. 2 is a schematic view showing a semiconductor laser chip.

3A and 3B are a cross-sectional view and a top view of a carrier.

4A and 4B are a top view and a cross-sectional view of a first strip line.

5A and 5B are a top view and a cross-sectional view of a second strip line.

6A and 6B are diagrams showing the return loss characteristics of the conventional semiconductor laser module and the semiconductor laser module of the present invention.

FIG. 7 is a schematic view showing a second mode of the semiconductor laser module of the present invention.

FIG. 8 is a view showing the strip line of the same.

FIG. 9 is a schematic view showing a third mode of the semiconductor laser module of the present invention.

FIG. 10 is a view showing the carrier of the same.

FIG. 11A is a circuit diagram showing a T-type attenuator,
(B) is a circuit diagram showing a π-type attenuator.

FIG. 12 is a schematic view showing a conventional semiconductor laser module.

FIG. 13 is a schematic view showing a semiconductor laser chip.

14A and 14B are a cross-sectional view and a top view of a carrier.

15A and 15B are a top view and a cross-sectional view showing a strip line.

[Explanation of symbols]

 1, 21 Semiconductor laser chip 2, 12, 22 Carrier 3, 23 Peltier cooler 4, 24 Storage case 5, 6, 16, 26 Strip line 5d, 16d, 12d Attenuator 7, 27 Ground plate 8a, 8b, 28a, 28b Lead 9a, 9b, 29a, 29b Insulating material 10, 30 Thin metal wire

Claims (4)

[Claims] 1. A semiconductor chip having at least a modulator integrated therein and having a modulation signal input electrode, a carrier on which the semiconductor chip is mounted, a storage case for storing the carrier together with the semiconductor chip, and a modulation signal from the outside. A semiconductor module comprising: a lead provided, a modulation signal transmission line electrically connecting the lead and the modulation signal input electrode, and an attenuator provided in the modulation signal transmission line. 2. The modulation signal transmission path is configured by a strip line that is provided so as to penetrate through a wall portion of the storage case, and the attenuator is provided on the strip line. 1. The semiconductor module according to 1. 3. The modulated signal transmission path is arranged between a first strip line penetrating a wall portion of the housing case and the first strip line and the carrier. The semiconductor module according to claim 1, wherein the semiconductor module is formed of a second strip line, and the attenuator is provided on the second strip line. 4. The semiconductor module according to claim 1, wherein the attenuator is provided on the carrier, and the modulation signal is given to the modulation signal input electrode via the attenuator.