JP2646971B2 - Semiconductor external modulator chip carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor external modulator, and more particularly, to a chip carrier on which a semiconductor external modulator chip is mounted (semiconductor external modulator chip carrier).

[0002]

2. Description of the Related Art A conventional chip carrier on which a semiconductor external modulator chip is mounted will be described with reference to FIGS. FIG. 4 is a schematic view of a conventional chip carrier, and FIG. 5 is an equivalent circuit diagram of FIG.

In the prior art, a semiconductor external modulator chip 2
Is mounted on the chip carrier 1 as shown in FIG. That is, the semiconductor external modulator chip 2 is mounted on the chip carrier 1 via the heat sink 3.

A thin-film resistor 4 is arranged on the left of the semiconductor external modulator chip 2, and a microstrip line 6 for signal transmission is arranged on the right of the semiconductor external modulator chip 2. As shown in FIG. 4, the microstrip line 6 is connected across the semiconductor external modulator chip 2 by cross bonding (bonding wire 5), while the other of the thin film resistors 4 is grounded, so that the chip carrier 1 itself is grounded. It has a structure bonded to. In FIG. 4, reference numeral 7 denotes a ceramic substrate.

A semiconductor external modulator is a kind of switch for turning on / off the passage of light emitted from a semiconductor laser diode or the like, and is expressed as a diode as shown in FIG. 5 in terms of an equivalent circuit. You. And, from outside,
It has the effect of transmitting and absorbing light in response to the application of a reverse bias signal.

In the case of FIG. 4, the light enters the semiconductor external modulator chip 2 in a direction perpendicular to the plane of FIG. The light is transmitted and absorbed according to the application of the forward / reverse bias of the voltage signal through the right microstrip line 6, whereby the light signal is modulated. That is,
This system does not directly modulate the light emission of the diode or the like, but modulates the emitted light by transmission and absorption outside.

At present, such a semiconductor external modulator has the following features:
It is used in optical communication systems of 5 Gb / s or more (it is difficult to use a laser diode for direct modulation). At this time, the voltage signal that modulates the semiconductor external modulator has a band of 2.
It is a signal in the microwave range of 5 GHz or more (so-called L band or more), and generally requires a transmission system with impedance matching.

When the semiconductor external modulator is turned on and off, the semiconductor external modulator is in a state similar to that of a diode at the time of forward / reverse bias. And is far from the impedance of 50 Ω which is common in microwave signals. Therefore, as shown in FIG. 4, the 50 Ω thin film resistor 4 formed on the ceramic By arranging the modulator in the immediate vicinity of the external modulator chip 2, impedance matching is achieved with respect to the microwave signal.

[0009]

The above-described prior art chip carrier has the following disadvantages. Since the thin film resistor 4 is used for impedance matching, it needs to be close to the semiconductor external modulator. Therefore, as shown in FIG. 4, it is arranged on the left side of the semiconductor external modulator chip 2 and connected by cross bonding (bonding wire 5) across the semiconductor external modulator chip 2 from the microstrip line 6 for signal transmission. ing. (The other of the thin film resistors 4 is bonded to the chip carrier 1 itself for grounding.)

In such cross-bonding, there is a risk that the wire may be bent over time and come into contact with the semiconductor external modulator chip 2 or the chip carrier 1 or the like. (Hereinafter referred to as "defect 1"). In order to avoid this cross bonding, for example, in FIG.
It is conceivable to dispose the thin film resistor 4 on the right side of the semiconductor external modulator chip 2. In this case, the length of the bonding wire 6 from the signal microstrip line 6 to the semiconductor external modulator chip 2 becomes longer, There is a disadvantage that it is disadvantageous in high frequency mounting.

Further, it is necessary to increase the width of the chip carrier 1 and secure an area for disposing the thin film resistor 4 beside the microstrip line 6 (in this case, the microstrip line 6 and the semiconductor external modulator chip 2). However, since the width of the chip carrier 1 is determined by the width of the semiconductor external modulator chip 2 itself, there is a disadvantage that the width of the chip carrier 1 cannot be increased.

This is because, although not shown in FIG. 4, optical systems such as optical fibers and lenses are arranged on both sides of the semiconductor external modulator chip 2 of the chip carrier 1.
In any case, if the thin-film resistor 4 is arranged in the immediate vicinity of the semiconductor external modulator chip 2, there is a disadvantage that cross bonding is inevitable.

The conventional technique shown in FIG. 4 also has another disadvantage as follows. That is, at the time of assembling the semiconductor external modulator, after bonding the microstrip line 6 and the semiconductor external modulator chip 2, the semiconductor external modulator is inspected for electrical damage due to the bonding. It is necessary to check the current / voltage characteristics of the chip 2. At this time, if the thin-film resistors 4 are bonded in parallel, the characteristics of the thin-film resistors 4 can be seen at the same time, so that the above-described check of the semiconductor external modulator chip 2 itself cannot be performed.

In order to solve the above problem, the bonding is actually divided into two stages. First, the semiconductor external modulator chip 2 and the microstrip line 6 are bonded without cross-bonding. The wire bonding process is performed twice, such as checking the voltage characteristics and then performing cross bonding. For this reason, the conventional technology has a drawback that the assembling process is complicated, resulting in an increase in man-hours and an increase in cost (hereinafter referred to as “defect 2”).

The conventional technique shown in FIG. 4 has another disadvantage as follows. That is, in the method of obtaining impedance matching by the immediate arrangement of the thin film resistors 4, there is no other way to expect that "matching is achieved" after actually assembling. If the desired characteristics are not obtained when the actual light modulation operation is performed after the chip carrier is assembled, it is determined whether the cause is in the semiconductor external modulator chip itself or in the way of impedance matching. The disadvantage of not being able to
(Hereinafter referred to as “defect 3”).

The present invention has been made in view of the above-mentioned drawbacks (including Nos. 1 to 3) and problems in the prior art, and an object of the present invention is to provide a semiconductor device which solves these drawbacks and problems. An external modulator chip carrier is provided.

That is, the present invention provides (1) eliminating cross-bonding in a semiconductor external modulator chip carrier, (2) enabling current-voltage characteristics to be checked in one wire bonding step, 3) An object of the present invention is to provide a semiconductor external modulator chip carrier whose main object is to enable monitoring of a signal input waveform.

[0018]

In order to achieve the above object, a chip carrier according to the present invention comprises a microstrip line for signal transmission, and the other end is provided with a characteristic impedance.
It has another microstrip line for impedance matching (terminated with a dance resistance element or an oscilloscope), and the two microstrip lines are bonded to each other at the end on the semiconductor external modulator side. And

With this configuration, the present invention is equivalently equivalent to the case where the resistance is terminated immediately near the semiconductor external modulator, and at the same time as achieving impedance matching for a high frequency signal, An object of the present invention is to provide a semiconductor external modulator chip carrier having a function as a monitor line for observing a signal input waveform.

That is, the present invention provides a semiconductor external modulator chip carrier comprising a microstrip line for transmitting an electric signal and a microstrip line for impedance matching, wherein the two microstrip lines are connected to each other. Having a structure in which the semiconductor external modulator chip is bonded immediately adjacent to the semiconductor external modulator chip. "

[0021]

Next, the present invention will be described in detail with reference to examples of the present invention.

(Embodiment 1) FIG. 1 is a schematic view of a chip carrier according to a first embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of FIG. The chip carrier 1 according to the first embodiment includes:
As shown in FIG. 1, the ceramic substrate 7 has a structure in which two microstrip lines (6a, 6b) are patterned.

One microstrip line (microstrip line 6a) is used for electric signal transmission as in the prior art, and the other microstrip line (microstrip line 6b) is used for impedance matching. The microstrip line 6b is bonded to the strip line 6a for transmitting an electric signal in the immediate vicinity of the semiconductor external modulator chip 2, and the other end is outside the chip carrier 1 as shown by an arrow in FIG. In addition, a chip resistor (50Ω) or an oscilloscope for monitoring (input impedance)
50Ω).

The two microstrip lines (6
Since the characteristic impedances of a and 6b) are selected to be 50Ω, if they are terminated with a chip resistance of 50Ω outside the chip carrier 1 as described above, the microstrip line 6a for transmitting electric signals is At the point of bonding (ie, immediately adjacent to the semiconductor external modulator chip 2),
This is equivalent to adding a 50Ω resistor. For this reason, the microstrip line 6b can take impedance matching with respect to the signal input to the semiconductor external modulator.

At this time, the characteristic impedance of the microstrip lines (6a, 6b) on the ceramic substrate 7 is:
The thickness of the ceramic substrate 7 and the microstrip line (6
a, 6b), the thickness of the ceramic substrate 7 is reduced so that even if two microstrip lines (6a, 6b) are inserted, the chip carrier 1
Can be realized without being changed.

In the first embodiment, since there is no need for cross-bonding, it is possible to eliminate the drawbacks of the prior art associated with the cross-bonding (the above-mentioned drawback 1). In the first embodiment, the end of the microstrip line 6b is connected to a chip resistor (or another resistive element capable of realizing 50Ω).
Can be implemented outside the chip carrier 1 by
Before attaching the chip resistor, there is an advantage that the current / voltage characteristics of the semiconductor external modulator chip 2 can be checked from outside through the microstrip line 6a.

For this reason, in the first embodiment, since a complicated wire bonding process is required only once, the other disadvantages of the prior art (the above-described disadvantage 2) can be solved and improved. It has become. Further, in the first embodiment, instead of the chip resistor, the input impedance can be terminated with an oscilloscope having an impedance of 50Ω. For this reason, it is possible to observe the input signal waveform in the immediate vicinity of the signal transmission path to the semiconductor external modulator, and it is easy to determine whether or not actual impedance matching has been achieved.
(Defect 3) can be solved, and this point can be further improved.

(Embodiment 2) FIG. 3 is a schematic view of a chip carrier according to a second embodiment of the present invention. In the second embodiment, the ceramic substrates 7 forming the microstrip lines (6a, 6b) are formed by lamination. That is, the microstrip line 6a for electric signal transmission is provided on the first-layer ceramic substrate 7a, and the microstrip line 6b for impedance matching is provided on the second-layer ceramic substrate 7a.
b. Note that, in the second embodiment, the structure can be reversed.

In the chip carrier according to the second embodiment, a laminated ceramic substrate (7a, 7b) is provided in a stage immediately adjacent to the semiconductor external modulator chip 2, and two microstrip lines (6a, 6b) are provided. There is. Therefore, if the microstrip lines (6a, 6b) are bonded to each other, the same effect as in the first embodiment can be realized. In this case, in the line of the second layer, since the ceramic substrate 7 is equivalently thick (the ground plane is far away), the line width of the strip line is adjusted to reduce the characteristic impedance of the line to 50Ω. It goes without saying that they are aligned.

[0030]

As described in detail above, the present invention has another microstrip line for impedance matching in addition to a microstrip line for signal transmission, and the above-mentioned two microstrip lines at the end of the semiconductor external modulator. It is characterized by bonding two microstrip lines to each other,
The aforementioned disadvantages of the prior art chip carrier 1
Various disadvantages including (3) can be solved, and the effect that these points can be improved is produced.

That is, according to the present invention, (1) the cross bonding can be eliminated, and the above-mentioned disadvantage 1 of the prior art associated with the cross bonding can be solved. (2) 1
A remarkable effect is obtained that the current / voltage characteristics can be checked in a single wire bonding step, and (3) the signal input waveform can be monitored.

[Brief description of the drawings]

FIG. 1 is a schematic view of a chip carrier showing a first embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram in FIG.

FIG. 3 is a schematic view of a chip carrier according to a second embodiment of the present invention.

FIG. 4 is a schematic view of a conventional chip carrier.

FIG. 5 is an equivalent circuit diagram in FIG.

[Explanation of symbols]

 Reference Signs List 1 chip carrier 2 semiconductor external modulator chip 3 heat sink 4 thin film resistor 5 bonding wire 6, 6a, 6b microstrip line 7, 7a, 7b ceramic substrate

Claims (3)

(57) [Claims] 1. A semiconductor element mounted on a chip carrier.
Light is incident on one end face of the side face of the
Light that enters the semiconductor element by the air signal
Outside semiconductors that modulate optical signals by transmitting and absorbing inside the body
And a semiconductor modulator on the chip carrier.
A plane parallel to the surface of the controller and parallel to the end face where light enters
An insulating substrate extending in various directions, and formed on the insulating substrate.
A first stripline for transmitting an electrical signal,
A first strip line having a strip line;
Is the semiconductor external modulator at the end closest to the semiconductor external modulator.
To the input terminal of the modulator through a bonding wire
And the half of the second stripline
Connect the end near the conductor external modulator and the bonding wire
And the other end of the second strip line is connected to an external terminal.
A semiconductor external transformer connected to a terminal resistor.
Conditioner chip carrier. 2. The first strip line and the first strip line.
And two strip lines are formed in parallel on the same insulating substrate.
The semiconductor device according to claim 1, wherein:
Modulator chip carrier. 3. The method according to claim 2, wherein the first strip line is a first insulation.
A second strip line formed on the substrate,
The first insulating substrate and the second insulating substrate formed on an edge substrate
2. The half according to claim 1, wherein the substrates are laminated.
Conductor external modulator chip carrier.