JP2000353848A - Semiconductor laser diode with optical modulator and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable rapid operation by raising separation resistance of an isolation part by forming a high resistance InP layer on a surface of both sides of a mesa part formed lower than a laser oscillation part and an optical modulator part in an isolation part. SOLUTION: A mesa 5 having a vertical side surface to a substrate 1 is formed and a recessed part 201 is formed in an isolation part 102 in a surface wherein a buried layer is formed by making the depth of the mesa 5 deep in the isolation part 102 and shallow in a laser oscillation part 103 and a modulator part 101. That is, if an n-type InP layer 62 is in contact with a mesa top and is set thick enough in the laser oscillation part 103 and the modulator part 101, the n-type InP layer 62 is formed apart from the mesa 5 in an isolation part. Therefore, the n-type InP 62 does not remain in the isolation mesa part 102, separation resistance of an isolation part can be made high, and rapid operation is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser with an optical modulator mainly used for an ultra-high-speed optical communication system.

[0002]

2. Description of the Related Art In order to transmit a large amount of data using a semiconductor laser and an optical fiber, it is necessary to modulate the semiconductor laser at a high speed. However, in the conventional method of directly modulating a single-mode semiconductor laser by changing an injection current,
Since the wavelength fluctuation (wavelength chirping) due to the fluctuation of the injected carrier density is large, it cannot be used for high-speed modulation of, for example, 10 Gbps or more.

Therefore, a method of modulating a semiconductor laser with an optical modulator having small wavelength chirping has been attracting attention instead of the conventional direct modulation method. The “laser with light modulator” is used for such an application. The laser with an optical modulator integrates a single-mode semiconductor laser and a high-speed optical modulator for modulating the semiconductor laser on a single chip, so that there is no need for a circuit between the optical modulator and the laser. It is extremely important as a key device for high-capacity optical communication. By the way, in order to realize high-speed operation of the laser with the optical modulator, it is necessary to reduce the electric capacity of the modulator section and increase the resistance of the isolation section between the laser and the modulator.

A conventional semiconductor laser diode with an optical modulator has the following configuration as shown in FIGS. Here, in FIGS. 48 and 49, (1)
nP substrate, (203) absorption layer (of modulator), (20)
5) is a mesa including an active layer and an absorption layer, (206) is a current blocking layer, (261) is a high-resistance InP layer, (262) is an n-type InP layer, (207) is a p-type InP cladding layer,
(208) is a p-type InGaAs contact layer, and (9) is a process mesa groove.

As shown in FIG. 48, in a semiconductor laser diode with an optical modulator, in order to increase the separation resistance of an isolation section 302 between a laser oscillation section 303 and a modulator section 301, (1) isolation Part 302
Removing the n-type InP layer 262 of (2) p-type InGa
The As contact layer 208 is removed. However, in (1), n-type InP
Since the layer 262 cannot be completely removed, the separation resistance between the laser oscillating unit 303 and the modulator unit 301 is reduced, and high-frequency leakage occurs, which often hinders high-speed operation. Problems of the conventional semiconductor laser diode with an optical modulator will be described in more detail according to a process flow.

In the conventional method of manufacturing a laser diode with an optical modulator, first, as shown in FIG. 39, an active layer 202 of a laser oscillation section 303 and a modulator section 30 are formed on an InP substrate 1.
After a predetermined crystal layer including the first absorption layer 203 is epitaxially grown, the active layer 202 and the active layer 202 are formed by wet etching using an etchant such as HBr using the insulating film 204 such as SiO _{2 having a} width of about 6 μm as a mask. Absorbing layer 2
Then, a mesa 205 including the “03” is formed. At this time, mesa 205
Of about 4 μm, active layer 202 or absorption layer 203
Is about 1.3 μm.

Next, as shown in FIG. 40, using the insulating film 204 such as SiO ₂ used for forming the mesa 205 as a selective growth mask, the current blocking layer 20 is formed on the side surface of the mesa 205.
6, the high-resistance InP layer 261 has a thickness of 2 to 3 μm, the n-type InP layer 262 has a thickness of about 1.0 μm,
The embedded growth is continuously performed by the CVD method. High resistance In
For example, Fe is used as a dopant of the P layer 261, and S is used as a dopant of the n-type InP layer 262, for example.

Here, the reason why the n-type InP layer 262 is provided on the high-resistance InP layer 261 will be described. If the p-type InP cladding layer 207 is grown directly on the high-resistance InP layer 261, Zn as a dopant of the p-type InP cladding layer 207 and Fe as a dopant of the high-resistance InP layer 261 inter-diffuse, resulting in a high resistance. This reduces the resistance of the InP layer 261. However, by providing the n-type InP layer 262 between the p-type InP cladding layer 207 and the high-resistance InP layer 261, Zn that is going to diffuse from the p-type InP cladding layer 207 toward the high-resistance InP layer 261 is n-type.
Since the type InP layer 262 traps, the resistance of the high-resistance InP layer 261 can be prevented from lowering.

A cross section taken along line EE 'of FIG. 40 (a cross section of the isolation portion 302) has the same shape as the modulator-side end face shown in FIG. 40, as shown in FIG. Next, as shown in FIG. 42, a position corresponding to the isolation portion 302 is dry-etched to a predetermined depth, thereby forming n of the isolation portion 302.
The type InP layer 262 is removed. At this time, if the etching amount is too small, the n-type InP layer 262 in a portion where the layer thickness is far away from the mesa 205 remains, and if the etching amount is too large, the active layer 202 of the laser unit 303 or Since the absorption layer 203 of the modulator section 301 is etched, the etching amount is about 0.6 μm as a depth at which the n-type InP layer 262 in a region inside the process mesa groove formed in a later step can be removed. Is set to If the removal of the n-type InP layer 262 is successful,
As shown in FIG. 43, in the cross section of the isolation portion 302, the n-type InP layer 262 is not completely removed.

Next, as shown in FIGS. 44 and 45, a p-type InP cladding layer 207 and a p-type InGaAs
A contact layer 208 is grown. Next, FIGS. 46 and 47
As shown in the figure, the p-type InGaAs
The contact layer 208 is removed by etching using an etching solution such as tartaric acid. Finally, as shown in FIG. 48, parallel process mesa grooves 9 are provided at intervals of about 5 to 7 μm to complete a semiconductor laser diode with an optical modulator. The cross section of the isolation portion 302 of the completed device is as shown in FIG. 49. The isolation resistance is reduced by removing the n-type InP layer 262, removing the p-type InGaAs contact layer 208, and forming the process mesa groove 9. Of high resistance.

As described above, the n-type InP layer 262 and the p-type InP
When the GaAs contact layer 208 is completely removed and the process mesa groove is completed to have a width of 5 to 7 μm, the separation resistance between the laser oscillation section 303 and the modulator section becomes more than ten Ω.

[0012]

However, there is actually a problem that the n-type InP layer 262 of the isolation portion 302 cannot be completely removed as shown in FIG. For example, as shown in FIG.
The nearby n-type InP layer 262 may remain. This is because the n-type InP layer 262 near the mesa 205 is in contact with the selective growth mask SiO _2, and
This is presumed to be due to the fact that P deteriorates and is hardly etched. As another example, the n-type InP layer 262
In order to prevent the active layer 202 and the absorption layer 203 from being etched when the layer is etched, the etching amount is set to a necessary minimum of about 0.6 μm, so that the n-type InP layer 262 grows thicker. In this case, as shown in FIG. 51, n-type InP layer 2 located inside process mesa groove 9 is formed.
62 remains. If even a small amount of the n-type InP layer 262 remains in the isolation section, the separation resistance between the laser oscillation section 303 and the modulator section drops to several Ω. As a result, there is a problem that high-frequency leakage occurs between the laser initial deep part and the modulator part, thereby impairing the high-speed operation of the laser diode with the modulator.

It is an object of the present invention to solve the conventional problems and to provide a semiconductor laser diode with a modulator capable of increasing the isolation resistance of an isolation section and operating at a high speed.

[0014]

To achieve the above object, a first semiconductor laser diode with an optical modulator according to the present invention is formed on an InP substrate in a belt shape from one end to the other end. A mesa portion, a high-resistance InP layer buried on both sides of the mesa portion, and the mesa portion and the high-resistance InP layer.
A p-type cladding layer formed on a p-layer, wherein the laser oscillation section at one end and the optical modulator section at the other end are separated by an isolation section, and the laser oscillation section and the optical modulator are separated from each other. A semiconductor laser diode with an optical modulator in which an n-type InP layer is formed between the high-resistance InP layer and the p-type cladding layer in the portion.
The P layer is grown on surfaces on both sides of the mesa portion formed to be lower than the laser oscillation portion and the optical modulator portion in the isolation portion. With this configuration, it is possible to provide a semiconductor laser diode with an optical modulator in which the n-type InP layer in the isolation portion is extremely small.

The first semiconductor laser diode with an optical modulator according to the present invention is characterized in that n
The mesa portion is formed by forming a semiconductor layer including an active layer on the InP substrate and removing the semiconductor layers on both sides of the mesa portion by dry etching in order to further reduce the remaining of the type InP layer. Is preferred.

Further, a second semiconductor laser diode with an optical modulator according to the present invention is formed by forming a band-shaped mesa portion from one end to the other end on an InP substrate, and burying the mesa portion on both sides of the mesa portion. A high-resistance InP layer, a p-type cladding layer formed on the mesa portion and the high-resistance InP layer, and a laser oscillation portion on one end and an optical modulator portion on the other end by an isolation portion. And the high-resistance InP in the laser oscillation section and the optical modulator section.
In a semiconductor laser diode with an optical modulator in which an n-type InP layer is formed between a layer and a p-type cladding layer, grooves are formed on both sides of the mesa, and the mesa is formed in the isolation. Both side surfaces of the mesa portion are respectively aligned with the side walls of the respective grooves, and both side surfaces of the mesa portion are located inside the side walls of the respective grooves in the laser oscillation portion and the optical modulator portion. It is characterized by being formed. With the above configuration, a semiconductor laser diode with an optical modulator can be manufactured without forming an n-type InP layer in the isolation part in the manufacturing process.

A third semiconductor laser diode with an optical modulator according to the present invention is formed by forming a mesa portion formed in a band shape from one end to the other end on an InP substrate and burying the mesa portion on both sides of the mesa portion. A high-resistance InP layer, a p-type cladding layer formed on the mesa portion and the high-resistance InP layer, and a laser oscillation portion on one end and an optical modulator portion on the other end by an isolation portion. And the high-resistance InP in the laser oscillation section and the optical modulator section.
In a semiconductor laser diode with an optical modulator in which an n-type InP layer is formed between a layer and a p-type cladding layer, the mesa section is substantially the same in the laser oscillation section, the isolation section, and the optical modulator section. And the high-resistance InP layer is grown using a selective growth mask wider than the laser oscillation section and the optical modulator section in the isolation section. With this configuration, it is possible to provide a semiconductor laser diode with an optical modulator in which the n-type InP layer in the isolation portion is extremely small.

Further, a fourth semiconductor laser diode with an optical modulator according to the present invention is formed by forming a band-shaped mesa portion from one end to the other end on an InP substrate and burying the mesa portion on both sides of the mesa portion. A high-resistance InP layer, a p-type cladding layer formed on the mesa portion and the high-resistance InP layer, and a laser oscillation portion on one end and an optical modulator portion on the other end by an isolation portion. And the high resistance In in the laser oscillation section and the optical modulator section.
In a semiconductor laser diode with an optical modulator in which an n-type InP layer is formed between a p-type layer and a p-type cladding layer,
The high-resistance InP layer is grown on both sides of the mesa section formed higher than the laser oscillation section and the optical modulator section in the isolation section. Even with such a configuration, a semiconductor laser diode with an optical modulator can be obtained in which the n-type InP layer in the isolation portion remains very little.

Still further, a fifth semiconductor laser diode with an optical modulator according to the present invention has a mesa portion formed in a band shape from one end to the other end on an InP substrate and buried on both sides of the mesa portion. A high-resistance InP layer, a p-type cladding layer formed on the mesa portion and the high-resistance InP layer, and a laser oscillation portion on one end and an optical modulator on the other end by an isolation portion. And a semiconductor laser diode with an optical modulator in which an n-type InP layer is formed between the p-type cladding layer and the high-resistance InP layer in the laser oscillation section and the optical modulator section. The high-resistance InP layer is grown so as to swell at a position apart from the mesa portion in the isolation portion. Even with such a configuration, a semiconductor laser diode with an optical modulator can be obtained in which the n-type InP layer in the isolation portion remains very little.

Further, in the second to fifth semiconductor laser diodes with an optical modulator according to the present invention, the mesa portion is formed by forming a semiconductor layer including an active layer on the semiconductor substrate, and forming the semiconductor layer on both sides of the mesa portion. Can be formed by removing the semiconductor by wet etching.

According to a first method of manufacturing a semiconductor laser diode with an optical modulator according to the present invention, a mesa portion formed in a band shape from one end to the other end on an InP substrate is provided. A semiconductor layer including the active layer on the InP substrate, wherein the semiconductor layer including the active layer is formed on the InP substrate. An etching step of forming a mesa portion by forming a mask corresponding to the portion and removing the semiconductor layers on both sides of the mask deeper than the laser oscillation portion and the optical modulator portion in the isolation portion; A high-resistance InP layer is grown on both sides of the mesa using the mask as a selective growth mask;
The laser oscillation section and the optical modulator section on the high-resistance InP layer reach the upper end of the mesa section, and the isolation section on the high-resistance InP layer reaches the upper end of the mesa. A growth step of growing an n-type InP layer so that the n-type
and a removing step of removing the nP layer.
By doing so, the above n
The n-type InP layer can be grown so as not to be in contact with the mesa part, and the remaining amount of the n-type InP layer in the isolation part in the removal step can be extremely reduced.

Also, a second method for manufacturing a laser diode with an optical modulator according to the present invention, comprising a mesa portion formed in a band shape from one end to the other end on an InP substrate, wherein the laser oscillation portion on one end side is provided. A semiconductor layer including the active layer on the InP substrate, wherein the semiconductor layer including the active layer is formed on the InP substrate. By forming a mask so as to be wider than the laser oscillation section and the optical modulator section in the isolation section corresponding to the section and removing the semiconductor layers on both sides of the mask, An etching step of forming a mesa portion whose width is larger than the width of the laser oscillation portion and the optical modulator portion; and a high resistance on both sides of the mesa portion using the mask as a selective growth mask. The nP layer is grown, the high-resistance InP
A growing step of growing an n-type InP layer on the layer; and forming the mesa portion at an interval wider than the width of the mesa portion in the laser oscillation portion and the optical modulator portion and smaller than the width of the mesa portion in the isolation portion. Groove forming step of forming two grooves parallel to each other so as to be symmetric with respect to. In this way, a semiconductor laser diode with an optical modulator can be manufactured without forming an n-type InP layer in the manufacturing process.

Further, a third method for manufacturing a semiconductor laser diode with an optical modulator according to the present invention comprises the steps of:
A semiconductor laser diode with an optical modulator, comprising a mesa portion formed in a band shape from one end to the other end, wherein the laser oscillation portion on the one end side and the optical modulator portion on the other end side are separated by an isolation portion; In the manufacturing method, a mask provided on the mesa portion and having a portion wider than the laser oscillation portion and the optical modulator portion in the isolation portion is used as a selective growth mask and high resistance is provided on both sides of the mesa portion. The method is characterized by including a growth step of growing an InP layer and growing an n-type InP layer on the high-resistance InP layer, and a removing step of removing the n-type InP layer in the isolation portion. With this configuration, the n-type InP layer can be grown so as not to be in contact with the mesa portion in the isolation portion, and the amount of the n-type InP layer remaining in the isolation portion in the removal step can be extremely reduced.

In the third method of manufacturing a semiconductor laser diode with an optical modulator according to the present invention, the isolating portion may be formed in the growth step so as to reduce the remaining amount of the n-type InP layer in the isolation portion. A mask provided with a plurality of wide portions in the translation portion may be used as a selective growth mask.

Further, a fourth method for manufacturing a semiconductor laser diode with an optical modulator according to the present invention comprises a mesa portion formed in a band shape from one end to the other end on an InP substrate, wherein the laser on one end side is provided. In a method of manufacturing a semiconductor laser diode with an optical modulator in which an oscillation unit and the optical modulator unit on the other end side are separated by an isolation unit, a semiconductor layer including the active layer is formed on the InP substrate, An etching step of forming a mask corresponding to the mesa portion and forming the mesa portion by removing semiconductor layers on both sides of the mask in the isolation portion to be shallower than the laser oscillation portion and the optical modulator portion; Growing a high-resistance InP layer using the mask as a selective growth mask until the high-resistance InP layer contacts the lower end of the selective growth mask in the isolation portion; A growth step on the resistive InP layer is grown an n-type InP layer, n-type I of the isolation unit
and a removing step of removing the nP layer.
By doing so, the above n
The n-type InP layer can be grown so as not to be in contact with the mesa part, and the remaining amount of the n-type InP layer in the isolation part in the removal step can be extremely reduced.

A fifth method for manufacturing a semiconductor laser diode with an optical modulator according to the present invention comprises a mesa portion formed in a band shape from one end to the other end on an InP substrate, wherein the laser on one end side is provided. In a method for manufacturing a semiconductor laser diode with an optical modulator, wherein an oscillation section and the optical modulator section on the other end side are separated by an isolation section, a selective growth mask provided on the mesa section, A high-resistance InP layer is grown on both sides of the mesa using a growth film thickness increasing mask provided at a predetermined interval on both sides of the selective growth mask.
The method includes a growth step of growing an n-type InP layer on the P layer, and a removing step of removing the n-type InP layer in the isolation part. With this configuration, the n-type InP layer can be grown so as not to be in contact with the mesa portion in the isolation portion, and the amount of the n-type InP layer remaining in the isolation portion in the removal step can be extremely reduced.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 and 2 show a semiconductor laser diode with an optical modulator according to a first embodiment of the present invention. FIG. 1 is a perspective view, and FIG. 2 is a sectional view taken along the line AA ′ in FIG. The semiconductor laser diode with an optical modulator according to the first embodiment is:
As shown in FIG. 1, a mesa 5 having a side surface perpendicular to the substrate 1 is formed, and the depth of the mesa 5 is made deeper in the isolation part 102 and shallower in the laser oscillation part 103 and the modulator part 101. As a result, a concave portion 201 is formed in the isolation portion 102 on the surface on which the buried layer is grown. With this configuration, the isolation mesa unit 10
2 realizes a semiconductor laser diode with an optical modulator in which the n-type InP layer 62 does not remain.

Hereinafter, the semiconductor laser with an optical modulator according to the first embodiment will be described.
The method of manufacturing a laser diode is described in the process shown in FIGS.
This will be described in detail using a process flow. In the figure,
1 and 2 are designated by the same reference numerals.
I have. In this manufacturing method, first, as shown in FIG.
An active layer 2 of a laser oscillation unit 103 and a modulator on a substrate 1
Epitaxial growth of a predetermined crystal layer including a part of the absorption layer 3
After that, a SiO 2 of about 2 μm width_TwoThe insulating film 4 made of
And then CH_Four-H _TwoDry etching using system gas
To form a mesa 5 including the active layer 2 and the absorption layer 3.
You. At this time, the mesa depth in the isolation section 102 is
Height (height) is about 0.5 μm deeper than other areas
The concave portion 201 is formed so as to be formed.

The vertical cross-sectional shape of the mesa 5 formed by dry etching is different from the conventional shape in which the mesa 5 is formed by wet etching, and the shape of the mesa 5 is a rectangle having a side wall substantially perpendicular to the substrate, unlike the shape in which the gentle hem is widened. Become. When the width of the SiO ₂ film 4 is about 2 μm and the depth of the mesa 5 is about 4 μm, the width of the active layer 2 or the absorption layer 3 is about 1.3 μm. Next, as shown in FIG. 4, using the SiO ₂ film 4 used for forming the mesa 5 as a selective growth mask, a high-resistance InP layer 61 and an n-type In
The P layer 62 is continuously buried and grown by MOCVD.

Here, a growth process and a buried shape when a rectangular mesa formed by dry etching is buried and grown by MOCVD using a selective growth mask will be described with reference to FIGS. First, as shown in FIG. 12, there is a growth process 1 until the (110) plane parallel to the mesa side wall disappears from the growth surface, and then, as shown in FIG. A growth process 2 until reaching the top of the mesa 5 follows, followed by a growth process 3 that grows on the (311) plane and the (001) plane as shown in FIG. In order to grow the crystal on the mesa side wall by MOCVD, HCl needs to be added during the growth.
Depending on the HCl flow rate to be added, (11
The growth rate of the 0) plane, and thus the length of the (111) B plane, can be controlled. In other words, by reducing the flow rate of HCl to be added, the relative growth rate on the (110) plane can be made higher than the growth rate directly above the (001) plane in the growth process 1, so that the (111) B plane Can be lengthened.

As described in the conventional example, the n-type InP layer 6
In order for the n-type InP layer 62 to function effectively as a layer for preventing the interdiffusion of Fe, a dopant of the high-resistance InP layer 61, and Zn, a dopant of the p-type InP cladding layer 7, the n-type InP layer 62 Mesa 5 in contact with the top
Even in the vicinity, it is desirable that the n-type InP layer 62 is grown to be as thick as the part away from the mesa 5. For this purpose, it is necessary to grow the high-resistance InP layer 61 in the growth processes 1 and 2, and to set the layer thickness so that the n-type InP layer 62 is grown at the same time as the growth process 3 is started.

According to the experimental results, when the mesa depth is about 4 μm, the high-resistance InP layer 61 has a thickness of 2 to 3 μm and an n-type InP layer.
If layer 62 is in the range of about 1.0 μm, the desired embedded shape,
In other words, the n-type InP layer 62 comes into contact with the top of the mesa 5 and a thick buried shape can be obtained even in the vicinity of the mesa 5. Embodiment 1 thus grown
The cross section of the isolation section 102 in FIG.
As shown in FIG. As described above, when the n-type InP layer 62 is set to have a sufficient thickness in contact with the top of the mesa in the laser oscillation section 103 and the modulator section 101, the isolation section has As shown in FIG. 5, the n-type InP layer 62 is formed apart from the mesa 5.
This is because the mesa depth of the isolation unit 102 is larger than that of the laser oscillation unit 103 or the modulator unit 101.
This is because the n-type InP layer 62 is grown in the growth process 2.

Next, as shown in FIGS. 6 and 7, in the isolation portion 102, dry etching is performed from the surface of the n-type InP layer 62 to a predetermined depth.
The n-type InP layer 62 of the isolation part 102 is removed. At this time, in the present invention, since the n-type InP layer 62 of the isolation part 102 is separated from the mesa 5, the n-type InP layer 62 does not remain near the mesa 5 as in the related art. Further, as described above, the length of the (111) B plane can be increased by reducing the flow rate of HCl added during the burying growth of the block layer 6, and the mesa 5 of the isolation portion 102 and the n-type InP Since the distance from the layer 62 can be increased, the n-type InP layer 6
2 is 5 to 7 μm in width of the process mesa groove 9 formed in a later step.
If it can be separated outside of m, the step of etching and removing the n-type InP layer 62 of the isolation part 102 itself can be eliminated, which can greatly contribute to simplification and stabilization of the step.

The subsequent process flow is basically the same as the conventional example. That is, as shown in FIGS. 8 and 9, the p-type InP cladding layer 7 and the p-type InG
aAs contact layer 8 is grown, and then FIGS.
As shown in FIG.
The aAs contact layer 8 is removed by etching, and finally, as shown in FIG. 1, a process mesa groove 9 having a width of 5 to 7 μm is provided to complete the semiconductor laser diode with an optical modulator according to the first embodiment. Isolation part 10 of completed device
2 has a cross section as shown in FIG.
2 was completely removed.

As described above, according to the first embodiment,
Since the n-type InP layer 62 of the isolation section 102 can be completely removed, a separation resistance of more than ten Ω can be obtained stably, and an element having good high-frequency characteristics and capable of high-speed operation can be manufactured with a high yield. be able to. Also, according to the first embodiment, the n-type I
Since the step of removing the nP layer 62 by etching itself can be eliminated, the steps can be simplified, the process can be stabilized, and the yield can be improved.

Embodiment 2 Next, a semiconductor laser diode with an optical modulator according to a second embodiment of the present invention will be described. FIG. 15 is a perspective view showing a semiconductor laser diode with an optical modulator according to the second embodiment, and FIG. 16 is a sectional view taken along line BB ′ in FIG. In the semiconductor laser diode with an optical modulator according to the second embodiment, the width of the active layer or the absorption layer of the isolation unit 102 is set to the width of the active layer 2 of the laser oscillation unit 103 or the absorption layer 2 of the modulator unit 101.
And the n-type InP layer 62 does not remain in the mesa 5a in the isolation part 102.

Hereinafter, a method of manufacturing the semiconductor laser diode with an optical modulator according to the second embodiment will be described with reference to FIGS. Note that, in the diagram shown in Embodiment 2,
Components similar to those used in the description of the first embodiment are denoted by the same reference numerals.

In this manufacturing method, first, as shown in FIG. 17, a predetermined crystal layer including the active layer 2 of the laser oscillation section 103 and the absorption layer 3 of the modulator section 101 is epitaxially grown on the InP substrate 1. Thereafter, the mesa 5a including the active layer 2 and the absorption layer 3 is formed by wet etching using the insulating film 4a such as SiO ₂ as an etching mask. At this time, the width of the insulating film 4a such as SiO ₂ is set to about 6 μm in the laser oscillation section 103 and the modulator section 101 as in the related art, and in the isolation section 102, the width of the mesa 5a is reduced in a process 1 so that it is larger than the width of the groove.
0 to 12 μm.

The mesa 5a is formed by performing wet etching using HBr or the like with the insulating film 4a such as SiO ₂ as an etching mask. At this time, the shape of the mesa 5a is
As in the conventional case, the shape becomes a gentle skirt spread shape. When etching is performed so that the mesa depth becomes about 4 μm, the width of the active layer 2 of the laser oscillation section 103 and the width of the absorption layer 3 of the modulator section 101 become about 1.3 μm as in the related art, while the isolation becomes smaller. The width of the absorption layer of the portion 102 is 5.5 to 7.5 μm, which is wider than the width of a process mesa formed in a later step.

Next, as shown in FIG. 18, using the SiO ₂ film 4a used for forming the mesa 5a as a selective growth mask, a high-resistance InP layer 61 as a current blocking layer 6 is formed on the side surface of the mesa 5a. The n-type InP layer 62 is continuously buried and grown by MOCVD. Here, FIG. 19 shows a cross section of the isolation section 102 in FIG.
As shown in FIG. 19, in the isolation portion 102, the width of the mesa 5a is about 7.5 μm, and the n-type InP
The layer 62 is formed outside the mesa 5a having a width of about 7.5 μm.

In the conventional semiconductor laser diode with an optical modulator, the isolation section 102 is thereafter set to about 0.6 μm.
It is necessary to perform a step of removing the n-type InP layer 62 of the isolation part 102 by dry etching by about m. However, in the second embodiment, the n-type InP layer 62 of the isolation part 102 exists only outside the mesa 5a having a width of about 7.5 μm. On the other hand, since the subsequent process mesa groove 9 is formed at a distance of 5 to 7 μm, the width of the process mesa formed in the step of forming the groove 9 is 5 to 7 μm, and the width of the mesa 5a of the isolation portion 102 is Therefore, there is no need to perform a step of removing the n-type InP layer 62 in the isolation portion by dry etching.

The subsequent process flow is basically the same as the conventional example. That is, as shown in FIGS. 20 and 21, the p-type InP cladding layer 7 and the p-type InP
The P contact layer 8 is grown, and then the p-type InGaAs contact layer 8 in the isolation part is removed by etching as shown in FIGS. 22 and 23. Finally, as shown in FIG. Thus, two process mesa grooves 9 parallel to each other are provided to complete the semiconductor laser diode with an optical modulator according to the second embodiment. The cross section of the isolation part 102 of the completed element is as shown in FIG.
As a matter of course, the n-type InP layer 62 does not exist in the isolation part.

As described above, according to the second embodiment,
Since a step of etching and removing the n-type InP layer 62 of the isolation part 102 is not required, the wafer process can be simplified, and a separation resistance of more than ten Ω can be stably obtained. An element which can operate at a good speed and can operate at a high yield can be manufactured.

Embodiment 3 FIG. Next, a method for manufacturing the semiconductor laser diode with an optical modulator according to the third embodiment of the present invention will be described with reference to FIGS. In the drawings used to describe the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals.

In this manufacturing method, first, as shown in FIG. 24, a predetermined crystal layer including the active layer 2 of the laser oscillation section and the absorption layer 3 of the modulator section is epitaxially grown on the InP substrate 1. forming an etching mask for forming the mesa 5a in the insulating film 4b of SiO ₂ or the like. At this time, in the third embodiment, the shape of the insulating film 4b such as SiO ₂ is devised. That is, the width of the insulating film 4b in the modulator section and the laser oscillation section is about 6 μm as in the conventional case, but the width of the insulating film 4b in the isolation section is widened to more than ten μm, and its length ( The length in the light traveling direction in the laser oscillation section or the modulator section is referred to, and in this case, the length is referred to as length X), which is set to several μm, which is smaller than the width.

When a mesa is formed by wet etching using the mask thus formed, side etching proceeds in three directions in a portion where the width of the insulating film of the isolation portion is wide. At this time, if the length X of the insulating film in the isolation part is set to [side etch amount × 2], the crystal is etched off (removed by etching) under the insulating film, as shown in FIG. Then, the insulating film becomes elongated eaves. The mesa 5 of the laser oscillation section and the modulator section
As in the conventional case, the shape of “a” is a gently spreading shape. When the depth of the mesa 5a is about 4 μm, the width of the active layer 2 or the absorption layer 3 is about 1.3 μm.

Next, as shown in FIG. 25, using the SiO ₂ film 4b used for forming the mesa 5a as a selective growth mask, a high-resistance InP layer 61 as a current blocking layer 6 is formed on the side surface of the mesa 5a. The n-type InP layer 62 is continuously buried and grown by MOCVD. At this time, the cross-sectional shape of the buried layer of the current blocking layer 6 in the laser oscillation section and the modulator section becomes the same as the conventional shape like the shape shown on the end face of the modulator section in FIG. As shown in FIG. 26, as the temperature rises when growing the current block layer, the elongation of the insulating film 4b hangs down, so that the high-resistance InP layer 61 grows from the InP substrate 1 side and the insulating film When the suspended eaves 4b are reached, no material gas for crystal growth is supplied under the eaves, so that the growth under the eaves is stopped. By growing the n-type InP layer 62 after the growth under the eaves is stopped, the n-type InP layer 62 can be embedded in a shape away from the mesa 5a.

Next, as shown in FIGS. 27 and 28, the n-type InP layer 62 in the isolation portion is removed by dry etching the position corresponding to the isolation portion by about 0.6 μm. At this time, in the third embodiment, since the n-type InP layer 62 of the isolation portion is separated from the mesa 5a, the n-type InP layer 62 does not remain near the mesa 5a as in the related art. If the length of the isolation portion of the insulating film 4b used as the selective growth mask is set to be wider than the process mesa width of 5 to 7 μm formed in the subsequent step, the n-type I
Since the nP layer 62 can exist only outside the process mesa, the step of etching and removing the n-type InP layer 62 in the isolation portion itself can be eliminated, which can greatly contribute to simplification and stabilization of the process. More preferred.

The subsequent process flow is basically the same as the conventional example. That is, p-type InP
Growing a cladding layer and a p-type InGaAs contact layer,
Next, the pInGaAs contact layer in the isolation portion is removed by etching, and finally, a process mesa groove having a width of 5 to 7 μm is provided to complete the semiconductor laser diode with an optical modulator according to the third embodiment.

As described above, according to the third embodiment,
By devising the shape of the selective growth mask of the isolation part as described above, the n-type InP layer can be separated from the mesa by a simple method, and the subsequent step of removing the n-type InP layer of the isolation part And n-type I near the mesa
The nP layer can be eliminated, and a separation resistance of more than ten Ω can be stably obtained. As a result, an element having good high-frequency characteristics and capable of operating at high speed can be obtained with a high yield. In addition, the width of the eaves of the selective growth mask of the isolation portion is made wider than the process mesa width, and the distance between the n-type InP layers on both sides of the mesa is made wider than the process mesa width. Since the step of removing the n-type InP layer 62 by etching can be eliminated, it is possible to greatly contribute to simplification of the step and stabilization of the process.

Embodiment 4 FIG. Next, a method for manufacturing the semiconductor laser diode with an optical modulator according to the fourth embodiment of the present invention will be described with reference to FIGS. 29 to 31, the same components as those described above are denoted by the same reference numerals. The fourth embodiment uses an insulating film 4c in which the number of the elongated eaves of the insulating film 4b in the third embodiment is two. Therefore, the semiconductor laser diode with the optical modulator according to the fourth embodiment has two or more regions in the isolation direction in which the n-type InP layer is removed in the waveguide direction. Hereinafter, a method for manufacturing the semiconductor laser diode with an optical modulator according to the fourth embodiment will be described in detail.

In this method, first, as shown in FIG. 29, a predetermined crystal layer including an active layer 2 of a laser oscillation section and an absorption layer 3 of a modulator section is epitaxially grown on an InP substrate 1 as in the conventional case. After that, an etching mask for forming a mesa is formed with an insulating film 4c such as SiO ₂ , and the mesa is formed by wet etching. As in the third embodiment, the size of the portion of the insulating film 4c corresponding to the elongated eaves is set to not more than [side etch amount × 2] of a width of more than 10 μm and a length X of several μm. In this way, even when the number of the elongated eaves is two or more, the mesa can be formed in the same shape as that of the third embodiment by using the side etching by the wet etching. In this figure, the number of the elongated eaves of the insulating film is two, but may be three or more.

FIGS. 30 and 31 show a high-resistance InP layer 61 and a n-type current blocking layer 6 on the side of the mesa 5a, using the insulating film 4c made of SiO ₂ as a selective growth mask.
The type InP layer 62 has just been continuously buried and grown by MOCVD. As in the fourth embodiment, S
If there are two or more elongated eaves of the insulating film 4c such as iO ₂ , each of the elongated eaves hangs down by the temperature rise during the growth of the block layer.
In the P layer 62, a region apart from the mesa 5a is formed by the number of eaves.

As described above, the fourth embodiment has the same operation and effects as those of the third embodiment, and furthermore, makes the number of elongated eaves of the selective growth mask of the isolation portion plural, thereby increasing the length of the eaves. The present invention can be applied to any isolation width without being limited to X. In addition, by making the width of the eaves of the selective growth mask of the isolation part wider than the width of the process mesa, n
If the distance between the n-type InP layers can be made wider than the process mesa width of 5 to 7 μm, the n-type In
As in the third embodiment, the step of etching and removing the P layer becomes unnecessary.

Embodiment 5 Hereinafter, a semiconductor laser diode with an optical modulator according to a fifth embodiment of the present invention will be described.
This will be described with reference to FIGS. 32 to 3
In 6, 1 is an n-type InP substrate, 2 is InGaAsP
Active layer, 3 an absorption layer, 63 a high resistance InP current blocking layer, 64 an n-type InP layer, 75 a p-type InP cladding layer, 76 a p-type InGaAs contact layer, 77 a Si
An insulating film such as O ₂ is shown. In the fifth embodiment, the width of the mask made of the SiO ₂ insulating film 77 is about 6 μm, and the width of the active layer is about 1.3 μm. Further, as a dopant of the high-resistance InP layer current blocking layer 63, for example, Fe can be used.

Here, in the fifth embodiment, the DFB-laser oscillating section and the modulator section have a depth of 4 as shown in FIG.
36 μm and a depth of 3 μm as shown in FIG.
After forming mesas having different depths, the high-resistance InP current blocking layer 3 is formed to a thickness of 3 μm and the n-type InP layer 64 is formed to a thickness of 1 μm.
And a total thickness of 4 μm, thereby increasing the isolation resistance in the element isolation portion.

That is, in the method of manufacturing a semiconductor laser diode with an optical modulator according to the fifth embodiment, when a mesa is formed, only the DFB-laser oscillation section and the modulator section are etched by 1 μm in advance by dry etching. Then, the entire area including the isolation portion is etched by 3 μm by wet etching to form mesas having different depths. Then, on both sides of the mesa, first, a high-resistance In
The P current blocking layer 3 is grown to a thickness of 3 μm. In this way, as shown in FIG. 35, in the DFB-laser oscillation section and the modulator section, both sides of the insulating film 77 and the high resistance In
While a gap is formed between the surface of the P current block layer 63 and the surface of the P current block layer 63, the high resistance InP current block layer 63 grows in the isolation portion to contact both sides of the insulating film 77 as shown in FIG. .

In this state, the n-type InP layer 64 is
When grown to a thickness of μm, as shown in FIG.
In the B-laser oscillation section and the modulator section, the n-type InP layer 64 is grown so as to be in contact with the mesa, whereas in the isolation section, n-type InP layer 64 is formed outside the insulating film 77 as shown in FIG.
A type InP layer 64 is grown away from the mesa.

Next, in this state, the n-type InP layer 64 on both sides of the SiO ₂ insulating film 77 is removed by etching about 1 μm using the SiO ₂ insulating film 77 as an etching mask. Then, the insulating film 77 is removed with a hydrofluoric acid-based aqueous solution, a p-type InP cladding layer 75 is grown to a thickness of about 1.5 μm on the entire surface, and the p-type InGaAs contact layer 76 is
Grow to a thickness of μm.

In the semiconductor laser diode with modulator configured as described above, the DF to which a forward voltage is applied
In the B-laser oscillating section, injected electrons and holes are blocked by the high-resistance (Fe-doped) InP layer 63 and the n-type InP layer 64, so that high-output operation is possible. On the other hand, since the low-resistance n-type InP 64 is removed in the element isolation section, the isolation resistance between the DFB-laser oscillation section and the modulator section can be increased, and when a high frequency is applied to the modulator section. Current leakage to the DFB-laser oscillation section, which is a problem, can be suppressed. In the fifth embodiment, specifically, an isolation resistance value of 10 kΩ or more can be secured, and the resistance can be increased five times or more as compared with the case where the n-type InP layer is not removed.

In the fifth embodiment, the n-type InP layer is removed only from the element isolation part. However, the n-type InP layer in the modulator part may be removed by the same method. In addition, specific numerical values such as the mesa depth and the thickness of the current blocking layer are shown as examples, and the present invention is not limited to these numerical values.

Embodiment 6 FIG. Hereinafter, a method for manufacturing the semiconductor laser diode with the optical modulator according to the sixth embodiment of the present invention will be described. In the manufacturing method according to the sixth embodiment, as shown in the plan view of FIG. 37, the growth rate is increased on both sides of the stripe-shaped SiO ₂ insulating film 77 also serving as a mask for forming a mesa in the isolation portion. This is characterized in that a high-resistance InP layer current block layer 63 and an n-type InP layer 64 are grown by forming a mask 77a for the formation. The manufacturing method according to the sixth embodiment uses MOCVD, MBE,
In a crystal growth method such as the one described above, the growth rate increases as the crystal growth area becomes smaller (for example, IEEE, JOURNAL).
OF QUANTUM ELECTRONICS. VO
L. 29. N0.6, JUNE 1993).

That is, in the manufacturing method of the sixth embodiment,
And the isolation portion SiO _TwoBoth sides of insulating film 77
Since a mask 77a for increasing the film thickness is formed in FIG.
As shown in the sectional view of FIG._TwoInsulating film 77 and film thickness increase
High-resistance InP current blocking layer
63 is grown thick so as to swell. This high resistance I
The nP current blocking layer is made of SiO_TwoFor insulating film 77 and film thickness increase
The mask 77a was grown so as to be in contact with each side surface.
Thereafter, when the p-type InP layer 64 is grown, as shown in FIG.
A p-type InP layer 64 is formed apart from mesa 5b.

In FIG. 38, a dotted line 80 indicates the shape of the laser oscillation section and the modulator section where the high-resistance InP current block layer 63 is grown without forming the film thickness increasing mask 77a. Therefore, in the laser oscillation section and the modulator section, the high-resistance InP current blocking layer 63 is grown so as to be in contact with the mesa 5b.

Thereafter, the n-type I
The nP layer 64 is removed, and SiO _TwoRemove mask 77
After that, the p-type InP cladding layer and the p-type InGaAs
When the contact layer is grown, n-type InP is formed only in the element isolation portion.
Semiconductor laser diode with optical modulator with removed structure
It is made. Even in the case described above, the same as in the fifth embodiment is performed.
The DFB-isolation between the laser oscillator and modulator
Resistance can be increased, and high frequency
If the voltage is applied to the DFB-laser oscillator,
Flow leakage can be suppressed.

[0066] Further, in the sixth embodiment, the dimension of the mask, for example, SiO ₂ insulating film 77 is about 6μm the center of the stripe portion, 10 [mu] m spacing between the center of the SiO ₂ insulating film 77 and the sides of the mask 77a The width of the mask 77a on both sides is set to 20 to 50 μm.

[0067]

As described in detail above, in the first semiconductor laser diode with an optical modulator according to the present invention, the high-resistance InP layer includes the isolation section and the laser oscillation section and the optical modulation section. Since it is grown on both sides of the mesa portion formed so as to be lower than the optical portion, the semiconductor laser diode with an optical modulator having an extremely small amount of n-type InP layer remaining in the isolation portion can be obtained. The separation resistance of the section can be increased, and high-speed operation can be performed.

In the first semiconductor laser diode with an optical modulator according to the present invention, the mesa portion is formed by forming a semiconductor layer including an active layer on the InP substrate, and the semiconductor layers on both sides of the mesa portion are formed. By forming by removing by dry etching, n
The remaining InP layer can be reduced, the isolation resistance of the isolation portion can be increased, and high-speed operation can be performed.

In the second semiconductor laser diode with an optical modulator according to the present invention, grooves are formed on both sides of the mesa portion, and the mesa portion is formed in the isolation portion.
Both side surfaces of the mesa portion are respectively aligned with the side walls of the respective grooves, and both side surfaces of the mesa portion are located inside the side walls of the respective grooves in the laser oscillation portion and the optical modulator portion. Since it is formed, it can be manufactured without forming any n-type InP layer in the isolation part in the manufacturing process.
A semiconductor laser diode with an optical modulator having no nP layer can be obtained. Therefore, the isolation resistance of the isolation section can be increased, and high-speed operation can be performed.

In a third semiconductor laser diode with an optical modulator according to the present invention, the mesa section has substantially the same width in the laser oscillation section, the isolation section and the optical modulator section, and The resistance InP layer is grown using a selective growth mask wider than the laser oscillation section and the optical modulator section in the isolation section. This makes it possible to obtain a semiconductor laser diode with an optical modulator in which the n-type InP layer remains very little in the isolation section, so that the isolation resistance of the isolation section can be increased and high-speed operation can be performed.

Further, in the fourth semiconductor laser diode with an optical modulator according to the present invention, the high-resistance InP layer is formed so as to be higher in the isolation section than in the laser oscillation section and the optical modulator section. The mesa portion is grown on both sides. This makes it possible to obtain a semiconductor laser diode with an optical modulator in which the n-type InP layer remains very little in the isolation section, so that the isolation resistance of the isolation section can be increased and high-speed operation can be performed.

Further, in the fifth semiconductor laser diode with an optical modulator according to the present invention, the high-resistance InP layer is
Since the isolation portion is grown so as to swell at a position away from the mesa portion, the n-type InP layer remaining in the isolation portion can be extremely reduced, so that the isolation resistance of the isolation portion can be increased and high-speed operation can be achieved. Can be made.

In the semiconductor laser diode with an optical modulator according to the second to fifth aspects of the present invention, the mesa portion is formed by forming a semiconductor layer including an active layer on the semiconductor substrate, and forming the semiconductor layer on both sides of the mesa portion. By forming the semiconductor by removing the semiconductor by wet etching, a mesa can be easily formed, and it can be manufactured at low cost.

Further, in the first method of manufacturing a semiconductor laser diode with an optical modulator according to the present invention, the isolation portion is etched so as to be deeper than the laser oscillation portion and the optical modulator portion, and the mesa portion is etched. Forming a high-resistance InP layer on both sides of the mesa portion, and then reaching the upper surface end of the mesa portion in the laser oscillation portion and the optical modulator portion, and forming the high-resistance IP
The above-mentioned isolation part on the nP layer includes a growth step of growing an n-type InP layer so as not to reach an upper end of the mesa, and a removing step of removing the n-type InP layer of the isolation part. . As a result, the n-type In
Since the residual amount of the P layer can be extremely reduced, the separation resistance of the isolation portion can be increased, and a laser diode with an optical modulator that can operate at high speed can be manufactured.

Further, according to the second method of manufacturing a laser diode with an optical modulator according to the present invention, the width of the mesa portion of the isolation portion is adjusted to the width of the laser oscillation portion and the optical modulator portion corresponding to the mask shape. An etching step for forming a wider mesa portion, and a high-resistance InP layer grown on both sides of the mesa portion using the mask as a selective growth mask.
A growing step of growing an n-type InP layer on the P layer; and forming the mesa at an interval wider than the width of the mesa in the laser oscillation section and the optical modulator and narrower than the width of the mesa in the isolation. Forming two grooves parallel to each other so as to be symmetrical with respect to the portion. Thereby, during the manufacturing process, the n-type InP
Since the laser diode is manufactured without forming a layer, a laser diode with an optical modulator capable of high-speed operation with high isolation resistance and no n-type InP layer in the isolation portion can be manufactured.

Further, in the third method of manufacturing a semiconductor laser diode with an optical modulator according to the present invention, the selective growth mask provided on the mesa portion and having a wide portion in the isolation portion is provided. A high-resistance InP layer is grown on both sides of the portion, and an n-type I
Since the method includes a growth step of growing the nP layer and a removing step of removing the n-type InP layer in the isolation section, the n-type InP layer is removed in the isolation section.
The layer can be grown so as not to be in contact with the mesa portion, and the remaining amount of the n-type InP layer in the isolation portion in the removal step can be extremely reduced. Therefore,
According to this manufacturing method, it is possible to manufacture a laser diode with an optical modulator that has a very small amount of the n-type InP layer remaining in the isolation portion and that can operate at high speed with high separation resistance.

In the third method of manufacturing a semiconductor laser diode with an optical modulator according to the present invention, in the growing step, a mask provided with a plurality of wide portions in the isolation portion is used as a selective growth mask. Thereby, the remaining amount of the n-type InP layer in the isolation portion can be further reduced. Therefore, according to this manufacturing method, it is possible to manufacture a laser diode with an optical modulator having a higher separation resistance and capable of operating at higher speed.

Further, in the fourth method of manufacturing a semiconductor laser diode with an optical modulator according to the present invention, a mask is formed corresponding to the mesa portion, and semiconductor layers on both sides of the mask are formed in the isolation portion. An etching step of forming the mesa portion by removing the laser oscillator portion and the light modulator portion more shallowly, and using the mask as a selective growth mask to make a high-resistance InP layer contact the lower end of the selective growth mask in the isolation portion; After growing to
Further, the method includes a growth step of growing an n-type InP layer on the high-resistance InP layer and a removing step of removing the n-type InP layer in the isolation section. The n-type InP layer can be grown so as not to be in contact with the mesa portion, and the remaining amount of the n-type InP layer in the isolation portion in the removing step can be extremely reduced. Therefore, according to the present manufacturing method, a laser diode with an optical modulator having a high separation resistance and capable of high-speed operation can be manufactured.

Further, according to a fifth method of manufacturing a semiconductor laser diode with an optical modulator according to the present invention, the selective growth mask provided on the mesa portion and the isolation portion are provided on both sides of the selective growth mask. After growing a high-resistance InP layer on both sides of the mesa portion using a growth-thickness increasing mask provided at an interval of, the n-type InP layer is further grown on the high-resistance InP layer, Since the n-type InP layer in the isolation portion is removed, the n-type InP layer can be grown in the isolation portion so as not to be in contact with the mesa portion. The amount of the remaining InP layer can be extremely reduced. Therefore, according to the present manufacturing method, a laser diode with an optical modulator having a high separation resistance and capable of high-speed operation can be manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a semiconductor laser diode with an optical modulator according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line AA ′ in FIG.

FIG. 3 is a perspective view after a mesa portion is formed in the method for manufacturing a semiconductor laser diode with an optical modulator according to the first embodiment.

FIG. 4 is a perspective view after a n-type InP layer is grown in the method for manufacturing a semiconductor laser diode with an optical modulator according to the first embodiment.

FIG. 5 is a cross-sectional view of the isolation section of FIG.

FIG. 6 is a perspective view after removing an n-type InP layer of an isolation portion in the method of manufacturing the semiconductor laser diode with an optical modulator according to the first embodiment.

FIG. 7 is a cross-sectional view of the isolation unit of FIG.

FIG. 8 is a perspective view after a p-type InGaAs contact layer is formed in the method of manufacturing the semiconductor laser diode with an optical modulator according to the first embodiment.

FIG. 9 is a cross-sectional view of the isolation section of FIG.

FIG. 10 is a cross-sectional view illustrating a method of manufacturing a semiconductor laser diode with an optical modulator according to the first embodiment.
FIG. 4 is a perspective view after removing a type InGaAs contact layer.

FIG. 11 is a cross-sectional view of the isolation section of FIG.

FIG. 12 is a drawing for explaining a growth process 1 for explaining the principle of the first embodiment.

FIG. 13 is a drawing for explaining a growth process 2 for explaining the principle of the first embodiment.

FIG. 14 is a drawing for explaining a growth process 3 for explaining the principle of the first embodiment.

FIG. 15 is a perspective view showing a configuration of a semiconductor laser diode with an optical modulator according to a second embodiment of the present invention.

16 is a sectional view taken along line BB ′ in FIG.

FIG. 17 is a perspective view after a mesa is formed in the method for manufacturing a semiconductor laser diode with an optical modulator according to the second embodiment.

FIG. 18 is a perspective view after burying and growing a current blocking layer in the method of manufacturing a semiconductor laser diode with an optical modulator according to the second embodiment.

FIG. 19 is a cross-sectional view of the isolation unit of FIG.

FIG. 20 is a perspective view after a p-type InP contact layer is formed in the method for manufacturing a semiconductor laser diode with an optical modulator according to the second embodiment.

21 is a cross-sectional view of the isolation unit shown in FIG.

FIG. 22 is a cross-sectional view illustrating a method of manufacturing a semiconductor laser diode with an optical modulator according to the second embodiment.
FIG. 4 is a perspective view after forming a type InP contact layer.

FIG. 23 is a cross-sectional view of the isolation unit of FIG.

FIG. 24 is a perspective view after a mesa is formed in the method for manufacturing a semiconductor laser diode with an optical modulator according to the third embodiment.

FIG. 25 is a perspective view after burying and growing a current blocking layer in the method of manufacturing a semiconductor laser diode with an optical modulator according to the third embodiment.

FIG. 26 is a cross-sectional view of the isolation unit of FIG.

FIG. 27 is a cross-sectional view illustrating a method for manufacturing a semiconductor laser diode with an optical modulator according to the third embodiment;
FIG. 4 is a perspective view after removing a mold InP layer.

FIG. 28 is a cross-sectional view of the isolation unit of FIG.

FIG. 29 is a perspective view after a mesa is formed in the method for manufacturing a semiconductor laser diode with an optical modulator according to the fourth embodiment.

FIG. 30 is a perspective view after burying and growing a current blocking layer in the method of manufacturing a semiconductor laser diode with an optical modulator according to the fourth embodiment.

FIG. 31 is a sectional view of the isolation unit of FIG. 30;

FIG. 32 is a perspective view showing a schematic configuration of a semiconductor laser diode with an optical modulator according to a fifth embodiment of the present invention.

FIG. 33 is a sectional view of the modulator section of FIG. 32;

FIG. 34 is a cross-sectional view of the isolation section of FIG.

FIG. 35 is a cross-sectional view of a modulator section after a high-resistance InP layer current block layer and an n-type InP layer are buried and grown in the method of manufacturing the semiconductor laser diode with an optical modulator according to the fifth embodiment.

FIG. 36 is a cross-sectional view of an isolation part after a high-resistance InP layer current block layer and an n-type InP layer are buried and grown in the method of manufacturing the semiconductor laser diode with an optical modulator according to the fifth embodiment.

FIG. 37 is a plan view showing a mask structure according to the sixth embodiment.

FIG. 38 is a cross-sectional view after a p-type InP layer is grown in the method for manufacturing a semiconductor laser diode with an optical modulator according to the sixth embodiment.

FIG. 39 is a perspective view after a mesa is formed in a method of manufacturing a conventional semiconductor laser diode with an optical modulator.

FIG. 40 is a perspective view after a current block layer is buried and grown in a method of manufacturing a conventional semiconductor laser diode with an optical modulator.

FIG. 41 is a sectional view taken along line EE ′ of FIG. 40;

FIG. 42 is a cross-sectional view illustrating a conventional method of manufacturing a semiconductor laser diode with an optical modulator.
It is a perspective view after removing a P layer.

FIG. 43 is a cross-sectional view of the isolation section of FIG. 42.

FIG. 44 is a perspective view after a p-type InP contact layer is formed in a conventional method for manufacturing a semiconductor laser diode with an optical modulator.

FIG. 45 is a cross-sectional view of the isolation unit of FIG. 44.

FIG. 46 is a cross-sectional view illustrating a conventional method for manufacturing a semiconductor laser diode with an optical modulator.
It is a perspective view after forming a P contact layer.

FIG. 47 is a cross-sectional view of the isolation unit of FIG. 46.

FIG. 48 is a perspective view showing the overall configuration of a conventional semiconductor laser diode with an optical modulator.

FIG. 49 is a sectional view taken along line FF ′ of FIG. 48;

FIG. 50 is a cross-sectional view of an example of an isolation unit for explaining a problem of the conventional example.

FIG. 51 is a cross-sectional view of another example of an isolation unit for explaining a problem of the conventional example.

[Explanation of symbols]

1 InP substrate, 2 active layer, 3 absorption layer, 4 insulating film, 5 mesa, 6 current block layer, 7,75 p-type I
nP cladding layer, 8,76 p-type InGaAs contact layer, 61 high-resistance InP layer, 62,64 n-type InP
Layer, 63 high-resistance InP current blocking layer, 77 SiO
₂ Insulating film, 77a Thickness increasing mask, 101 Modulator section, 102 Isolation section, 103 Laser oscillation section, 201 recess.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Takiguchi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Yutaka Mihashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Ryo Denki Co., Ltd. (reference) 2H079 AA02 AA13 BA01 CA05 DA16 DA22 EA07 EB06 JA04 KA18 5F043 AA15 BB08 DD15 DD30 FF05 GG06 GG10 5F073 AA22 AA64 AA89 AB12 AB21 BA01 CA12 CB02 CB11 DA05 DA24 DA24

Claims (13)

[Claims] 1. A mesa portion formed in a band shape from one end to the other end on an InP substrate, a high-resistance InP layer buried and grown on both sides of the mesa portion, the mesa portion and the high-resistance InP layer A laser oscillation section on one end side and an optical modulator section on the other end side are separated by an isolation section, and the p-type cladding layer is formed on the laser oscillation section and the optical modulator section. On the high resistance InP layer and p
In the semiconductor laser diode with an optical modulator having an n-type InP layer formed between the semiconductor laser diode and the mold cladding layer, the high-resistance InP layer is lower in the isolation section than in the laser oscillation section and the optical modulator section. A semiconductor laser diode with an optical modulator, which is grown on both sides of the mesa formed as described above. 2. The mesa portion according to claim 1, wherein a semiconductor layer including an active layer is formed on the InP substrate, and the semiconductor layers on both sides of the mesa portion are removed by dry etching. Semiconductor laser diode with optical modulator. 3. A mesa portion formed in a band shape from one end to the other end on an InP substrate, a high-resistance InP layer buried and grown on both sides of the mesa portion, the mesa portion and the high-resistance InP layer. A laser oscillation section on one end side and an optical modulator section on the other end side are separated by an isolation section, and the p-type cladding layer is formed on the laser oscillation section and the optical modulator section. On the high resistance InP layer and p
A semiconductor laser diode with an optical modulator in which an n-type InP layer is formed between the semiconductor layer and a mold clad layer, wherein a groove is formed on both sides of the mesa section, and the mesa section is formed in the isolation section. Both side surfaces are respectively formed so as to coincide with the side walls of the respective grooves, and both side surfaces of the mesa portion are located inside the side walls of the respective grooves in the laser oscillation portion and the optical modulator portion. A semiconductor laser diode with an optical modulator. 4. A mesa portion formed in a belt shape from one end to the other end on an InP substrate, a high-resistance InP layer buried and grown on both sides of the mesa portion, the mesa portion and the high-resistance InP layer. A laser oscillation section on one end side and an optical modulator section on the other end side are separated by an isolation section, and the p-type cladding layer is formed on the laser oscillation section and the optical modulator section. On the high resistance InP layer and p
A semiconductor laser diode with an optical modulator having an n-type InP layer formed between the semiconductor laser diode and the mold cladding layer, wherein the mesa section has substantially the same width in the laser oscillation section, the isolation section, and the optical modulator section. The semiconductor laser diode with an optical modulator, wherein the high-resistance InP layer is grown in the isolation section using a selective growth mask having a width wider than that of the laser oscillation section and the optical modulator section. 5. A mesa portion formed in a band shape from one end to the other end on an InP substrate, a high-resistance InP layer buried and grown on both sides of the mesa portion, the mesa portion and the high-resistance InP layer. A laser oscillation section on one end side and an optical modulator section on the other end side are separated by an isolation section, and the p-type cladding layer is formed on the laser oscillation section and the optical modulator section. On the high resistance InP layer and p
In the semiconductor laser diode with an optical modulator having an n-type InP layer formed between the semiconductor laser diode and the mold cladding layer, the high-resistance InP layer is higher in the isolation section than in the laser oscillation section and the optical modulator section. A semiconductor laser diode with an optical modulator, which is grown on both sides of the mesa formed as described above. 6. A mesa portion formed in a band shape from one end to the other end on an InP substrate, a high-resistance InP layer buried and grown on both sides of the mesa portion, the mesa portion and the high-resistance InP layer. A laser oscillation section on one end side and an optical modulator section on the other end side are separated by an isolation section, and the p-type cladding layer is formed on the laser oscillation section and the optical modulator section. On the high resistance InP layer and p
In a semiconductor laser diode with an optical modulator in which an n-type InP layer is formed between the high-resistance InP layer and the n-type cladding layer, the high-resistance InP layer is grown so as to swell at a position away from the mesa in the isolation part. A semiconductor laser diode with an optical modulator. 7. The mesa portion is formed by forming a semiconductor layer including an active layer on the semiconductor substrate and removing semiconductors on both sides of the mesa portion by wet etching.
The laser diode with an optical modulator according to claim 3, wherein the pair of grooves are formed by wet etching. 8. An InP substrate, comprising a mesa portion formed in a band shape from one end to the other end, wherein the laser oscillation portion on one end side and the optical modulator portion on the other end side are separated by an isolation portion. A method for manufacturing a semiconductor laser diode with an optical modulator, comprising: forming a semiconductor layer including the active layer on the InP substrate; forming a mask corresponding to the mesa portion; and forming semiconductor layers on both sides of the mask. An etching step of forming the mesa section so as to be removed deeper than the laser oscillation section and the optical modulator section in the isolation section; and a high-resistance InP layer on both sides of the mesa section using the mask as a selective growth mask. In the laser oscillation section and the optical modulator section on the high-resistance InP layer, reaching the upper end of the mesa section, and forming the isolator on the high-resistance InP layer. An optical modulator comprising: a growth step of growing an n-type InP layer so as not to reach an upper end of the mesa in the isolation portion; and a removing step of removing the n-type InP layer in the isolation portion. Of manufacturing a semiconductor laser diode with a semiconductor device. 9. An InP substrate having a mesa portion formed in a band shape from one end to the other end, wherein the laser oscillation portion on one end side and the optical modulator portion on the other end side are separated by an isolation portion. A method of manufacturing a semiconductor laser diode with an optical modulator, comprising: forming a semiconductor layer including the active layer on the InP substrate; and forming the laser oscillation section and the light by the isolation section corresponding to the mesa section. By forming a mask so as to be wider than the modulator section and removing the semiconductor layers on both sides of the mask, the width of the mesa section of the isolation section is reduced by the width of the laser oscillation section and the width of the optical modulator section. An etching step for forming a wider mesa portion; a high-resistance InP layer grown on both sides of the mesa portion using the mask as a selective growth mask; and an n-type InP layer grown on the high-resistance InP layer. And a growth step, which is wider than the width of the mesa section in the laser oscillation section and the optical modulator section and narrower than the width of the mesa section in the isolation section so as to be symmetric with respect to the mesa section. Forming a groove in which two parallel grooves are formed. 10. A mesa section formed in a band shape from one end to the other end on an InP substrate, wherein the laser oscillation section on one end side and the optical modulator section on the other end side are separated by an isolation section. The method of manufacturing a semiconductor laser diode with an optical modulator according to claim 1, further comprising: selectively growing a mask provided on said mesa portion, said mask having a portion wider than said laser oscillation portion and said optical modulator portion in said isolation portion. A high-resistance InP layer is grown on both sides of the mesa portion as a mask,
A method for manufacturing a semiconductor laser diode with an optical modulator, comprising: a growing step of growing an n-type InP layer on a layer; and a removing step of removing the n-type InP layer in the isolation part. 11. The method for manufacturing a semiconductor laser diode with an optical modulator according to claim 10, wherein in said growing step, a mask having a plurality of wide portions in said isolation portion is used as a selective growth mask. 12. A mesa portion formed in a band shape from one end to the other end on an InP substrate, wherein the laser oscillation portion on one end side and the optical modulator portion on the other end side are separated by an isolation portion. A method for manufacturing a semiconductor laser diode with an optical modulator, comprising: forming a semiconductor layer including the active layer on the InP substrate; forming a mask corresponding to the mesa portion; and forming semiconductor layers on both sides of the mask. An etching step of forming the mesa section by removing the shallower than the laser oscillation section and the optical modulator section in the isolation section; and forming a high-resistance InP layer in the isolation section using the mask as a selective growth mask. A growth step of growing an n-type InP layer on the high-resistance InP layer after growing the layer until it contacts the lower end of the selective growth mask; And removing the n-type InP layer in the semiconductor laser diode with the optical modulator. 13. An InP substrate, comprising a mesa portion formed in a band shape from one end to the other end, wherein the laser oscillation portion on one end side and the optical modulator portion on the other end side are separated by an isolation portion. A method of manufacturing a semiconductor laser diode with an optical modulator, comprising: a selective growth mask provided on the mesa portion; and a growth provided on the isolation portion on both sides of the selective growth mask at a predetermined interval. A step of growing a high-resistance InP layer on both sides of the mesa portion using a film thickness increasing mask, and further growing an n-type InP layer on the high-resistance InP layer; A method of manufacturing a semiconductor laser diode with an optical modulator, comprising: a removing step of removing an InP layer.