JP2004207588A - Manufacturing method of multi-wavelength semiconductor laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a multi-wavelength semiconductor laser different from the conventional one of such a multi-wavelength semiconductor laser. <P>SOLUTION: On a semiconductor wafer 12, a first semiconductor laser element 18 is first formed, and the laminate structure 22 of a second surface luminescent semiconductor laser element having an oscillation wavelength band different from an oscillation wavelength band of the first semiconductor laser element is next formed and etched to form a second semiconductor laser element 24. The laminate structure 28 of a third surface luminescent semiconductor laser element having an oscillation wavelength band different from the oscillation wavelength bands of the first and second semiconductor laser elements is formed and etched to form a third semiconductor laser element 30. Fourth and fifth surface luminescent semiconductor laser elements or the like are formed as needed. Thus, a multi-wavelength semiconductor laser 10 equipped with a great number of semicoductor laser elements with mutually different oscillation wavelength bands can be produced. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of manufacturing a monolithic multi-wavelength semiconductor laser, and more particularly, to a simple method of manufacturing a monolithic multi-wavelength semiconductor laser including a plurality of semiconductor laser elements having different oscillation wavelength bands on a common semiconductor substrate. The present invention relates to a method that can be easily manufactured by a process.
[0002]
[Prior art]
2. Description of the Related Art In recent years, semiconductor lasers have been required to have various advanced functions with the progress of processing technology. While the function of the semiconductor laser element itself is becoming more sophisticated, a multi-wavelength semiconductor laser, which is not a single laser, such as a two-wavelength laser for CD / DVD reproduction and a multi-beam laser for a high-speed laser beam printer, is attracting attention.
These are packages in which a plurality of semiconductor laser elements are packaged as one package, and a plurality of semiconductor laser elements of the same wavelength or a plurality of semiconductor laser elements of different wavelength bands are independently driven to form a light source. This is for high integration.
[0003]
For example, Japanese Patent Application Laid-Open No. 2001-77457 includes a semiconductor laser device that emits a laser beam having a wavelength of 780 nm and a semiconductor laser device that emits a laser beam having a wavelength of 650 nm to reduce the variation in reflectance. For this purpose, a semiconductor laser in which a dielectric film is provided on an end face of an active layer and a method of manufacturing the same are disclosed.
[0004]
[Patent Document 1]
JP 2001-77457 A (FIG. 1)
[0005]
[Problems to be solved by the invention]
By the way, also in the field of optical communication, there is a demand for a characteristic semiconductor laser device utilizing such a high integration technology in the field of long wavelength lasers for optical communication.
In the field of long-wavelength lasers for next-generation optical communication such as the 1.3 μm band and the 1.55 μm band, wavelength division multiplexing (WDM) technology that enables large-capacity communication is being developed. However, the semiconductor laser devices using the same semiconductor material are exclusively used for arraying and high performance, and most of them are mainly semiconductor laser devices for light sources which are used in a backbone system.
[0006]
Therefore, an object of the present invention is to provide a method of manufacturing a multi-wavelength semiconductor laser that is different from a conventional method of manufacturing a multi-wavelength semiconductor laser, and in particular, is optimal for a long-wavelength laser for next-generation optical communication. .
[0007]
[Means for Solving the Problems]
In order to solve the problem, the inventor of the present invention independently drives a multi-wavelength semiconductor laser using a different material system for an active layer, such as the above-described two-wavelength laser for CD & DVD reproduction and a multi-beam laser for a high-speed laser beam printer. We considered that the high integration technology cultivated in consumer device technology could be further applied to long wavelength lasers for optical communication.
[0008]
That is, the present inventor has studied a method of manufacturing a multi-wavelength semiconductor laser in which a plurality of long-wavelength lasers for optical communication having greatly different oscillation wavelength bands, that is, different material systems are mixedly mounted on the same substrate.
Then, similarly to the two-wavelength laser for an optical disc, the semiconductor laser device having a different wavelength of the multi-wavelength semiconductor laser is selectively operated, or, unlike the two-wavelength laser for the optical disc, a semiconductor laser having a different wavelength of the multi-wavelength semiconductor laser is used. By operating the devices simultaneously, we considered realizing a high-performance optical communication device for consumer use, for example, short-distance communication in homes, which is expected in the future.
The present inventor has developed a method of manufacturing a multi-wavelength semiconductor laser most suitable for such purpose, and has come to invent the method of the present invention.
[0009]
Also, by combining a cleaved edge emitting semiconductor laser device and a vertical cavity surface emitting semiconductor laser device on the same substrate, and further combining it with a light receiving device (PD: PhotoDiode), a new optical communication multi-directional device with different light emitting directions is provided. Task We have developed a method for fabricating multi-wavelength semiconductor lasers that enables fabrication of multi-wavelength devices.
[0010]
In order to achieve the above object, based on the above findings, a method for manufacturing a multi-wavelength semiconductor laser according to the present invention comprises a compound semiconductor layer constituting a first semiconductor laser device having a first oscillation wavelength band. Forming a first stacked structure on a semiconductor substrate;
Etching the first stacked structure to form a first semiconductor laser device on a predetermined region of the semiconductor substrate and exposing the semiconductor substrate in a region other than a region where the first semiconductor laser device is formed;
Forming a second laminated structure made of a compound semiconductor layer constituting a second semiconductor laser device having a second oscillation wavelength band different from the first oscillation wavelength band on the entire surface of the substrate;
The second laminated structure is etched to form a second semiconductor laser device on a predetermined region of the semiconductor substrate other than the region where the first semiconductor laser device is formed, and to form the first semiconductor laser device and the second semiconductor laser device. Exposing the semiconductor substrate in an area other than the laser element formation area,
If necessary, the third, fourth,... Having the third, fourth,... Oscillation wavelength bands different from the first and second oscillation wavelength bands and different from each other in the same manner. Forming a semiconductor laser device on a semiconductor substrate;
It is characterized by having.
[0011]
In the method of the present invention, for example, the MOCVD method can be suitably used without any limitation as a method of forming each compound semiconductor layer constituting the laminated structure.
The method of the present invention is a method of manufacturing a two-wavelength laser having two semiconductor laser elements having completely different wavelength bands mounted on the same substrate and developed for the purpose of enabling reproduction of a CD and a DVD by one optical pickup. It has been further developed and applied to the manufacture of a multi-wavelength semiconductor laser.
According to the method of the present invention, a monolithic multi-wavelength semiconductor laser including a plurality of semiconductor laser elements having different oscillation wavelength bands can be easily manufactured without being limited by the number of semiconductor laser elements to be constituted.
[0012]
In a preferred embodiment of the method of the present invention, when forming a laminated structure of compound semiconductor layers constituting the first, second, third, fourth,... The semiconductor laser devices are formed in order from the semiconductor laser device having the highest optimum growth temperature of the active layer to the semiconductor laser device having the lowest optimum temperature.
Further, when the optimum growth temperature of the active layer is the same, each semiconductor laser element is formed in the order of the semiconductor laser element having the highest optimum growth temperature of the clad layer and the semiconductor laser element having the lowest optimum growth temperature according to the order of the optimum growth temperature of the clad layer. .
[0013]
In a preferred embodiment of the present invention, a substrate whose crystal structure is a zinc blend structure is used. By using a substrate having a zinc blend structure, processes such as cleavage and processing used in the production of a conventional semiconductor laser element or semiconductor device can be applied, and there is an effect that the material substrate can be easily made into a device. Here, the zinc blend structure is a zinc blende (ZnS) type crystal structure, and is a typical crystal present in a III-V group, II-V group, or I-III-VI group semiconductor. Structure.
In addition, as the semiconductor substrate, a semiconductor substrate whose off angle is more than 0 ° with respect to the {100} plane and which is off in the direction of the {0-1-1} plane (A plane) at an angle of 2 ° or less is used. A semiconductor substrate which is turned off in the {0-1-1} plane (A plane) at an angle of 2 ° to 30 ° with respect to the {100} plane is used.
[0014]
In the manufacturing process of multi-wavelength semiconductor lasers, etching and crystal growth using different semiconductor materials are repeated many times, so the surface morphology of the crystal growth film deteriorates and the processing accuracy of subsequent processes decreases due to the deterioration of the surface morphology. Inconveniences related to the quality and yield of the product may easily occur.
Therefore, in the method of the present invention, the growth order of the DH structure of each semiconductor laser device is determined based on the level of the optimum crystal growth temperature of the active layer, thereby preventing the deterioration of the crystallinity and improving the quality. By employing the substrate, it is possible to suppress deterioration of the surface morphology of the crystal growth film.
[0015]
Although the method of the present invention can be applied without limitation to the composition of the semiconductor substrate and without limitation to the composition of the compound semiconductor layer constituting the semiconductor laser device, preferably, the semiconductor substrate is made of a group III-V compound semiconductor. A semiconductor substrate is used. Specifically, a GaAs substrate or an InP substrate is used as a semiconductor substrate. In particular, a GaAs substrate is desirable because it has a high lattice matching with GaInN, AlGaInP, AlGaAs, AlGaInAsP, and AlGaInNPAsSb compound semiconductor layers.
The active layers of the first, second, third, fourth,... Semiconductor laser elements are made of a material obtained by combining at least two elements of Al, Ga, In, N, P, As, and Sb. Let it grow.
Thereby, a multi-wavelength semiconductor laser having an oscillation wavelength band of 400 nm band or more, and further, at least two wavelength bands of 650 nm band, 780 nm band, 850 nm band, 1.0 μm band, 1.3 μm band, and 1.55 μm band. A multi-wavelength semiconductor laser having an oscillation wavelength can be manufactured.
[0016]
In the method of the present invention, a cleaved edge emitting semiconductor laser device can be formed as the first, second, third, fourth,... Semiconductor laser device, and a vertical cavity surface emitting semiconductor laser device can be formed. Can also be formed. Also, at least one cleaved end surface emitting semiconductor laser device and the remaining vertical cavity surface emitting semiconductor laser device are formed as the first, second, third, fourth,... Semiconductor laser devices. You can also.
[0017]
In the field of development of semiconductor laser devices, semiconductor laser devices for optical communication are attracting attention, but at this stage, semiconductor laser devices for optical communication for large-capacity optical communication (main line) are mainly being developed.
It is expected that demand for optical communication lasers for general consumers such as LAN (Local Area Network) and SAN (Storage Area Network) will gradually increase in the future. Recently, commercialization of a vertical cavity surface emitting semiconductor laser device (VCSEL) has been attempted. A feature of the VCSEL is that it has a high coupling efficiency with an optical fiber, and is promising as a device for optical communication between substrates.
By applying the method of the present invention, it is possible not only to diversify the oscillation wavelength band on the same substrate, but also to easily manufacture a monolithic multi-wavelength semiconductor laser in which the light emitting directions are different by 90 °.
[0018]
Further, in addition to the first, second, third, fourth,... Semiconductor laser elements, the oscillation wavelength band of the first, second, third, fourth,. At least one corresponding light receiving element can be formed on a semiconductor substrate. As a result, the method of the present invention not only manufactures a semiconductor laser device having an oscillation wavelength band different from each other, but also realizes a multi-wavelength light receiving and emitting light which is conscious of a multi-wavelength semiconductor laser for the next generation optical communication which is currently attracting attention. A highly integrated device can be realized.
By mounting a light receiving element and a simple wiring pattern by the method of the present invention, a highly integrated multitasking light emitting / receiving IC (Integrated Circuit) can be easily manufactured. In addition, by forming a DH structure of a type suitable for an optical disk, optical wire communication (optical wire transmission), optical wireless communication (optical wireless transmission), or the like on the same substrate, the number of device components and the size of the substrate are increased. Therefore, it is possible to easily manufacture an optical device that satisfies the requirements as a new functional device for an optical set product.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail based on exemplary embodiments with reference to the accompanying drawings. The conductivity type, film type, film thickness, film forming method, other dimensions, and the like shown in the following embodiments are examples for facilitating understanding of the present invention, and the present invention is not limited to these examples. It is not done.
Embodiment 1
The present embodiment is an example of an embodiment of a method for manufacturing a multi-wavelength semiconductor laser according to the present invention. FIGS. 1A to 1C and FIGS. 2D to 2F are cross-sectional views of the substrate in each step when manufacturing a multi-wavelength semiconductor laser according to the method of the present embodiment.
In the present embodiment, the first semiconductor laser element 18, the second semiconductor laser element 24, and the third semiconductor laser element 30 having different oscillation wavelengths from each other, and further the fourth,. A multi-wavelength semiconductor laser including a laser element on a common semiconductor substrate is formed.
[0020]
First, a required compound semiconductor layer is epitaxially grown on a semiconductor substrate 12 by a MOCVD method or the like in the same manner as a conventional method of manufacturing a single semiconductor laser device, and an active layer 14 is formed as shown in FIG. A DH (double heterojunction) structure 16 is formed, which constitutes a first semiconductor laser device that emits laser light in a first oscillation wavelength band.
[0021]
Next, the DH structure 16 on the semiconductor substrate 12 is etched to provide a DH structure 16 having an active layer 14 on a predetermined region of the semiconductor substrate 12 as shown in FIG. A first semiconductor laser element that emits laser light in a wavelength range is formed, and a surface of the semiconductor substrate in a region other than a region where the first semiconductor laser element is formed is exposed.
Next, as shown in FIG. 1C, a required compound semiconductor layer of a material system different from the material system of the first semiconductor laser element 18 is epitaxially grown on the entire surface of the substrate by MOCVD or the like, so that the active layer 20 is formed. Then, a DH structure 22 constituting a second semiconductor laser device that emits a laser beam in a second oscillation wavelength band different from that of the first semiconductor laser device 18 is formed on the semiconductor substrate 12.
[0022]
Next, the DH structure 22 on the semiconductor substrate 12 is etched to form an active layer 20 on a predetermined region of the semiconductor substrate 12 other than the region where the first semiconductor laser element 18 is formed, as shown in FIG. And a second semiconductor laser element 24 that emits laser light in a second oscillation wavelength range. At the same time, the surface of the semiconductor substrate 12 in a region other than the region where the first semiconductor laser element 18 and the second semiconductor laser element 24 are formed is exposed.
Next, as shown in FIG. 2E, a required compound semiconductor layer of a material system different from the material system of the first semiconductor laser device 18 and the second semiconductor laser device 24 is epitaxially grown on the entire surface of the substrate by MOCVD or the like. A DH structure 28 having an active layer 26 and constituting a third semiconductor laser device having a third oscillation wavelength band different from that of the first semiconductor laser device 18 and the second semiconductor laser device 22 is formed by a semiconductor. It is formed on a substrate 12.
[0023]
Subsequently, as shown in FIG. 2F, the DH structure 28 on the semiconductor substrate 12 is etched to remove the DH structure 28 on the semiconductor substrate 12 other than the regions where the first semiconductor laser element 18 and the second semiconductor laser element 24 are formed. A third semiconductor laser element 30 including a DH structure 28 having an active layer 26 on a predetermined region and emitting laser light in a third oscillation wavelength range is formed.
At the same time, the surface of the semiconductor substrate 12 in a region other than the region where the first semiconductor laser device 18, the second semiconductor laser device 22, and the third semiconductor laser device 26 are formed is exposed.
As a result, the multi-wavelength semiconductor laser 10 including the first semiconductor laser device 18, the second semiconductor laser device 24, and the third semiconductor laser device 30 having different oscillation wavelengths on the common semiconductor substrate 12 is formed. be able to.
[0024]
Hereinafter, similarly, if necessary, a multi-wavelength semiconductor laser in which the fourth semiconductor laser device, the fifth semiconductor laser device,... Are formed on the semiconductor substrate 12 can be manufactured.
According to the method of this embodiment, a monolithic multi-wavelength semiconductor laser including a plurality of semiconductor laser elements formed of mutually different material systems and having mutually different oscillation wavelength bands can be easily manufactured.
[0025]
Embodiment 2
This embodiment is another example of the embodiment of the method for manufacturing a multi-wavelength semiconductor laser according to the present invention. FIGS. 3A to 3C and FIGS. 4D to 4F are cross-sectional views of the substrate in each step when manufacturing the multi-wavelength semiconductor laser according to the method of the present embodiment. 3 and FIG. 4 that are the same as those shown in FIG. 1 and FIG.
In the present embodiment, the first semiconductor laser device 18, the second semiconductor laser device 24, and the third semiconductor laser device 30 of the first embodiment have an arrangement different from the arrangement of the first semiconductor laser element Third semiconductor laser elements 18, 24, 30 are formed on the semiconductor substrate 12.
[0026]
As in the first embodiment, first, a required compound semiconductor layer is epitaxially grown on the semiconductor substrate 12 by MOCVD or the like in the same manner as in the conventional method of manufacturing a single semiconductor laser element, and FIG. Thus, a DH (double heterojunction) structure 16 that has the active layer 14 and constitutes a first semiconductor laser device that emits laser light in the first oscillation wavelength band is formed.
Next, the DH structure 16 on the semiconductor substrate 12 is etched to form a DH structure 16 having an active layer 14 on a predetermined region of the same semiconductor substrate 12 as in the first embodiment, as shown in FIG. A first semiconductor laser element 18 that emits laser light in a first oscillation wavelength range is formed. At the same time, the surface of the semiconductor substrate 12 in a region other than the region where the first semiconductor laser element 18 is formed is exposed.
[0027]
Next, as shown in FIG. 3C, a required compound semiconductor layer of a material system different from the material system of the first semiconductor laser element 18 is epitaxially grown on the entire surface of the substrate by MOCVD or the like, so that the active layer 20 is formed. Then, a DH structure 22 constituting a second semiconductor laser device that emits a laser beam in a second oscillation wavelength band different from that of the first semiconductor laser device 18 is formed on the semiconductor substrate 12.
[0028]
Next, in the present embodiment, an etching mask having a mask pattern different from that of the first embodiment is formed on the substrate, and the DH structure 22 on the semiconductor substrate 12 is etched by changing the etching region from the first embodiment. Then, as shown in FIG. 4D, a DH structure 22 having an active layer 20 is provided on a predetermined region of the semiconductor substrate 12 different from that of the first embodiment, and laser light in the second oscillation wavelength range is emitted. A second semiconductor laser element 24 that emits light is formed on the semiconductor substrate 12.
At the same time, the surface of the semiconductor substrate 12 in a region other than the region where the first semiconductor laser device 18 and the second semiconductor laser device 24 are formed is exposed.
[0029]
Next, as shown in FIG. 4E, a required compound semiconductor layer of a material different from the material system of the first semiconductor laser device 18 and the second semiconductor laser device 24 is epitaxially grown on the entire surface of the substrate by MOCVD or the like. A DH structure 28 having an active layer 26 and constituting a third semiconductor laser device having a third oscillation wavelength band different from the first semiconductor laser device 18 and the second semiconductor laser device 24 is formed by a semiconductor. It is formed on a substrate 12.
[0030]
Subsequently, an etching mask having a mask pattern different from that of the first embodiment is formed on the substrate, and the DH structure 28 on the semiconductor substrate 12 is etched by changing the etching region from that of the first embodiment. As shown in (f), a DH structure 28 having an active layer 26 is provided on a predetermined region of the semiconductor substrate 12 other than the region where the first semiconductor laser device 18 and the second semiconductor laser device 24 are formed, and A third semiconductor laser device 30 that emits laser light in an oscillation wavelength range is formed on the semiconductor substrate 12.
At the same time, the surface of the semiconductor substrate 12 in a region other than the region where the first semiconductor laser device 18, the second semiconductor laser device 22, and the third semiconductor laser device 26 are formed is exposed.
[0031]
Through the above steps, the first semiconductor laser device 18, the second semiconductor laser device 24, and the third semiconductor laser device 30 of the first embodiment are arranged in a different manner from the first semiconductor laser device 18 on the semiconductor substrate 12. A multi-wavelength semiconductor laser 31 having the third semiconductor laser element formed on the semiconductor substrate 12 can be manufactured.
[0032]
As can be seen from the examples of the first and second embodiments, according to the method of the present invention, the semiconductor laser device is designed so that the in-plane distribution of the etching rate of the uneven surface of the semiconductor substrate 12 is made uniform according to the material system. The position can be optimized.
[0033]
Formation order of semiconductor laser devices based on optimal growth temperature
By the way, the semiconductor material used for the active layer has its own optimum crystal growth temperature. Therefore, when forming a DH structure that defines the oscillation wavelength of the semiconductor laser device, the temperature is higher than the optimum crystal growth temperature. Epitaxial growth may degrade the crystal of the compound semiconductor layer. Therefore, the order of crystal growth of each DH structure is an important factor that affects device quality.
Therefore, when the optimum crystal growth temperature of the semiconductor material used for the light emitting layer (active layer) of each DH structure formed on the same substrate is different, the optimum growth temperature of the active layer is determined according to the order of the optimum growth temperature of the active layer. It is necessary to form each semiconductor laser element in order from a semiconductor laser element having a high semiconductor laser element to a semiconductor laser element having a low semiconductor laser element.
[0034]
Therefore, in the first and second embodiments, the optimum crystal growth temperature becomes higher in the order of the active layers 26, 20, and 14. Therefore, by growing the active layer 14, the active layer 20, and the active layer 26 in this order, It is possible to minimize the influence of the thermal history of the active layer 14 that has grown on the growth temperature of the next grown active layer 20 and further the active layer 26.
Conversely, when the active layer 20 having an optimum crystal growth temperature lower than the optimum crystal growth temperature of the active layer 14 is first grown, when growing the active layer 14, the active layer 20 has a higher growth temperature of the active layer 14. Under the influence, the probability and extent of desorption of elements constituting the active layer 20, interdiffusion with other compound semiconductor layers, for example, elements constituting the guide layer and the cladding layer, and causing a problem in crystallinity are increased. .
[0035]
The DH structure includes a clad layer, a guide layer, an active layer, and the like. Therefore, when the optimum crystal growth temperature of each layer forming one DH structure is different, the layers other than the active layer, in particular, the DH structures having the same clad layer are put together and the optimum crystal growth temperature of the active layer is compared. It is also possible to determine the growth order of each DH structure such that the influence of the thermal history is most suppressed.
In particular, since the cladding layer has the longest growth time among the compound semiconductor layers constituting the DH structure, the order of the growing DH structures is determined by focusing on the growth temperature and the growth time of the cladding layer. It is desirable to decide.
[0036]
Preferred semiconductor substrate
As a semiconductor substrate material for a multi-wavelength semiconductor laser for various uses including an optical communication light source, a GaAs substrate or an InP substrate is preferable.
Among the semiconductor substrate materials, a GaAs substrate has a high lattice matching with a GaInN-based, AlGaInP-based, AlGaAs-based, AlGaInAsP-based, or AlGaInNPAsSb-based compound semiconductor layer. Accordingly, the GaAs substrate is used as a light source for storage in a 400 nm band (blue: Cubic, GaInN system), a 650 nm band (red: AlGaInP system), and a 780 nm DH structure band (near infrared: AlGaAs system), and optical communication. Of multi-wavelength semiconductor lasers covering a wide wavelength band such as 850 nm to 1.0 μm band (near infrared: AlGaInAsP system) and 1.3 μm to 1.55 μm band (infrared: AlGaInNPAsSb system) used as a light source for semiconductors Ideal as a substrate.
That is, among the crystal growth techniques at this stage, it can be evaluated that the GaAs substrate is the most preferable substrate for the multi-wavelength semiconductor laser.
[0037]
According to the method of the present invention, when forming a multi-wavelength semiconductor laser on a GaAs substrate and an InP substrate, the oscillation wavelength band of each DH structure for the multi-wavelength semiconductor laser, the kind of material required for the same, and the optimum crystal growth of the material FIG. 5 is a table briefly summarizing the relationship with the temperature.
As can be seen from FIG. 5, even with the same oscillation wavelength band, that is, the same active layer material, the longer the wavelength, the higher the growth temperature of the cladding layer becomes higher than the growth temperature of the active layer. Therefore, it is preferable to use growth conditions that make the growth temperature of the cladding layer as close as possible to the growth temperature of the active layer.
[0038]
For this purpose, for example, when the MOCVD method is applied, a semiconductor material gas that decomposes at a lower temperature than before, such as TBAs (tertiary butyl arsine) and TBP (tertiary butyl phosphine), all of which can be introduced as an organometallic gas. The problem can be solved by employing an organometallic material gas having a tertiary butyl group such as the above as a semiconductor material source for group III and group V.
By unifying the crystal growth temperatures of the active layer and the cladding layer to almost the same temperature using the above-mentioned organometallic material gas, it is possible to easily determine each order of the DH structure growth for the multi-wavelength semiconductor laser. Become. Further, by using the above-mentioned organometallic material gas, it becomes possible to grow a high-quality device film in which the thermal history of the already grown DH structure is minimized.
[0039]
Embodiment 3
The present embodiment is still another example of the embodiment of the method of manufacturing a multi-wavelength semiconductor laser according to the present invention. Although not shown, the semiconductor substrate 12 has an off angle of (100) 2 ° A off to (100). It is the same as the first embodiment or the second embodiment except that a 15 ° A off substrate is used.
When applying the method of the present invention, as can be seen from the first and second embodiments, in the process of producing each DH structure having a mutually different configuration, re-etching and re-crystal growth are repeated more often.
Then, the repetition of the etching may damage the substrate surface and deteriorate the surface morphology after crystal growth.
[0040]
In the present embodiment, an off substrate having an off angle of (100) 2 ° A off to (100) 15 ° A off is used as the semiconductor substrate 12. Thereby, as shown in FIG. 6, the deterioration of the surface morphology after the crystal growth, which occurs in the (100) just substrate, can be remarkably improved.
FIGS. 6A to 6E are optical microscope photographs of the surface morphology of the (100) just substrate, the 2 ° A off substrate, the 4 ° A off substrate, the 10 ° A off substrate, and the 15 ° A off substrate, respectively. It is a copy of. The optical micrographs of the surface morphology shown in FIGS. 6A and 6D have been submitted to the JPO together with the present specification as reference photographs.
[0041]
As described above, when crystal growth of the DH structure is performed on the substrate that has been repeatedly etched, the substrate surface morphology after the crystal growth may be deteriorated.
Therefore, in the present embodiment, a semiconductor substrate turned off in the {0-1-1} direction with respect to the {100} plane, for example, an off angle of (100) 2 ° A off to (100) 15 ° A off The substrate is used as the semiconductor substrate 12 to suppress the deterioration of the surface morphology and to form a good crystalline laminated structure.
In particular, when a substrate having a zinc blend type crystal structure is used, an off-substrate is preferable.
[0042]
As an example using a technique similar to this, as disclosed in Japanese Patent Application Laid-Open No. 2002-166524, a so-called SDH (Separated Double Heterostructure) semiconductor laser device is manufactured using a GaAs ridge (concavo-convex) structure substrate. There is a way.
In the manufacture of SDH semiconductor laser devices, the deterioration of surface morphology after laser crystal growth is solved by employing an off-structure substrate. This is because the step growth on the off-substrate promotes a regular atomic arrangement and makes it possible to improve the surface morphology of the semiconductor device, which deteriorates due to complicated processes.
[0043]
As an example of using an off-substrate in a semiconductor laser device other than an SDH laser, Japanese Patent Application Laid-Open No. 2001-77457 discloses a combination of an AlGaInP-based DH structure (red laser) and an AlGaAs-based DH structure (near-infrared laser). Two-wavelength lasers have been reported.
The reason why the off-substrate is used in the invention of the above-mentioned publication is to take into consideration that the atomic arrangement of the AlGaInP-based crystal, which is the material constituting the red laser, has a natural superlattice structure, and to suppress this. .
[0044]
In addition, in the invention of the above-mentioned publication, the surface morphology after crystal growth of a multi-wavelength semiconductor laser is severely deteriorated in the manufacture of a two-wavelength laser, even though a re-etching and re-growth process is repeated a plurality of times. There is no.
As a result of comparing the AlGaInP-based DH structure and the AlGaAs-based DH structure from the viewpoint of the optimum crystal growth temperature, an off-substrate is used for the AlGaAs-based DH structure (near-infrared laser) that needs to grow crystals first. Because it is.
As a result, the off-substrate has been adopted as a base for the two-wavelength laser even for the AlGaAs-based DH structure which does not need to use the off-substrate from the past results.
[0045]
Example of manufacturing an SDH semiconductor laser device with improved surface morphology using an off-substrate, and a two-wavelength laser combining an AlGaInP-based DH structure (red laser) and an AlGaAs-based DH structure (near-infrared laser) Similarly to the case of the above, when a multi-wavelength semiconductor laser is manufactured by the method of the present invention, a substrate having an off angle of (100) 2 ° A off to (100) 15 ° A off is used as the semiconductor substrate 12. The surface morphology after crystal growth can be improved.
[0046]
Embodiment 4
The present embodiment is a further example of the embodiment of the method for manufacturing a semiconductor laser device according to the present invention, and FIG. 7 is a schematic diagram showing the configuration of a multi-wavelength semiconductor laser manufactured by the manufacturing method of the present embodiment. It is sectional drawing.
This embodiment is different from the first to third embodiments in that, instead of the cleaved edge emitting semiconductor laser device, a plurality of mutually different oscillation wavelengths are provided on a common semiconductor substrate 32 as shown in FIG. This is a method for manufacturing a multi-wavelength semiconductor laser 40 including first to third vertical cavity surface emitting semiconductor laser elements 34, 46, 38.
[0047]
In recent years, research and development reports and product announcements of vertical cavity surface emitting semiconductor laser devices have become active with the advancement of communication laser functions.
The method of the present invention is applicable not only to the manufacture of a multi-wavelength semiconductor laser device having a 650 nm band or 780 nm band cleaved edge emitting semiconductor laser device, but also to a multi-wavelength semiconductor laser device having a plurality of vertical cavity surface emitting semiconductor laser devices having different wavelengths. It can also be applied to the manufacture of wavelength semiconductor lasers.
[0048]
In the formation of a DH structure of a vertical cavity surface emitting semiconductor laser device, it is necessary to provide a multilayer reflective layer (DBR mirror: Distributed Bragg Reflector) before and after the active layer. Only different.
In the method of the present invention, basically, the multi-wavelength structuring is performed by changing the mask pattern used in the etching process. Therefore, when forming the vertical cavity surface emitting semiconductor laser device, the mask pattern at the time of etching is required. Is appropriately switched from that for the cleaved end face resonator to that for the vertical resonator, whereby a vertical cavity surface emitting semiconductor laser device can be formed.
[0049]
Therefore, in the present embodiment, as in the first and second embodiments, first, the first surface emitting semiconductor laser element 34 having the DH structure and the DBR mirror is formed on the semiconductor substrate 32, and then the second A DH structure of the surface emitting semiconductor laser element 36 and a compound semiconductor laminated structure forming the DBR mirror are formed and etched to form the second surface emitting semiconductor laser element 36.
Hereinafter, similarly, the third surface emitting semiconductor laser element 38 is formed, and if necessary, the fourth and fifth surface emitting semiconductor laser elements are formed.
Thus, a multi-wavelength semiconductor laser 40 including a plurality of first to third vertical cavity surface emitting semiconductor laser elements 34, 46, and 38 having different oscillation wavelengths on a common semiconductor substrate 32 is manufactured. can do.
[0050]
Embodiment 5
The present embodiment is a further example of the embodiment of the method for manufacturing a semiconductor laser device according to the present invention, and FIG. 8 is a schematic view showing a configuration of a multi-wavelength semiconductor laser manufactured by the manufacturing method of the present embodiment. It is sectional drawing.
In the present embodiment, as shown in FIG. 8, on a common semiconductor substrate 42, a cleaved edge emitting semiconductor laser device 44, a vertical cavity surface emitting device having an oscillation wavelength different from that of the cleaved edge emitting semiconductor laser device 44 are provided. A multi-task optical integrated device 50 including a type semiconductor laser element 46 and a photodiode 48 as a light receiving element is also manufactured for the purpose of optical communication between substrates.
By applying the method of the present invention to form a cleaved edge-emitting semiconductor laser device 44, then forming a vertical cavity surface-emitting semiconductor laser device 46, and then forming a photodiode 48, The optical integrated device 50 can be easily manufactured.
[0051]
【The invention's effect】
According to the method of the present invention, first, a first semiconductor laser device is formed on a semiconductor substrate, and then a second surface emitting semiconductor laser having an oscillation wavelength band different from the oscillation wavelength band of the first semiconductor laser device. A stacked structure of the device is formed and etched to form a second semiconductor laser device. Hereinafter, similarly, a third surface emitting semiconductor laser device is formed, and if necessary, fourth and fifth surface emitting semiconductor laser devices are formed.
As a result, a monolithic multi-wavelength semiconductor laser having a plurality of semiconductor laser elements having different oscillation wavelengths can be easily manufactured by a conventional simple process.
[0052]
Also, in the manufacturing process of a multi-wavelength semiconductor laser, crystal growth and etching using different semiconductor materials are repeatedly performed many times, so that the surface morphology of the crystal growth film is deteriorated, and the processing accuracy of a subsequent process is reduced due to the deterioration of the surface morphology. Inconveniences related to device quality and yield may easily occur.
Therefore, in the method of the present invention, the order of forming the laminated structure of each semiconductor laser element is determined based on the level of the optimum crystal growth temperature of the active layer, thereby preventing the deterioration of the crystallinity of the active layer and improving the quality. By employing an off-substrate, deterioration of the surface morphology of the crystal growth film can be suppressed, and a multi-wavelength semiconductor laser having excellent characteristics can be manufactured.
[Brief description of the drawings]
FIGS. 1A to 1C are cross-sectional views of a substrate in each process when manufacturing a multi-wavelength semiconductor laser according to the method of Embodiment 1. FIGS.
FIGS. 2 (d) to 2 (f) are cross-sectional views of a substrate in each step of manufacturing the multi-wavelength semiconductor laser according to the method of Embodiment 1 following FIG. 1 (c). .
3 (a) to 3 (c) are cross-sectional views of a substrate for each process when manufacturing a multi-wavelength semiconductor laser according to the method of Embodiment 2. FIG.
FIGS. 4D to 4F are cross-sectional views of a substrate in each step of manufacturing the multi-wavelength semiconductor laser according to the method of the second embodiment, following FIG. 3C; .
FIG. 5 is a table showing an optimum crystal growth temperature of a compound semiconductor layer.
FIGS. 6A to 6E are surface morphologies of a (100) just substrate, a 2 ° A off substrate, a 4 ° A off substrate, a 10 ° A off substrate, and a 15 ° A off substrate, respectively. 3 is a copy of an optical microscope photograph of FIG.
FIG. 7 is a schematic cross-sectional view illustrating a configuration of a multi-wavelength semiconductor laser manufactured by a manufacturing method according to a fourth embodiment.
FIG. 8 is a schematic cross-sectional view illustrating a configuration of a multi-wavelength semiconductor laser manufactured by a manufacturing method according to a fifth embodiment.
[Explanation of symbols]
10 multi-wavelength semiconductor laser, 12 semiconductor substrate, 14 active layer, 16 DH structure, 18 first semiconductor laser element, 20 active layer, 22 DH structure, 24 , A second semiconductor laser element, 26, an active layer, 28, a DH structure, 30 a third semiconductor laser element, 31, a multi-wavelength semiconductor laser manufactured by the method of the second embodiment, 32, Semiconductor substrate, 34 first vertical cavity surface emitting semiconductor laser device, 36 second vertical cavity surface emitting semiconductor laser device, 38 vertical cavity surface emitting semiconductor laser device, 40 .. A multi-wavelength semiconductor laser manufactured by the method of the fifth embodiment,..., A semiconductor substrate,..., A cleaved edge emitting semiconductor laser device,... A vertical cavity surface emitting semiconductor laser device,. , 50 ... Multi-tasking optical integrated device.

Claims (13)

Forming a first laminated structure of a compound semiconductor layer constituting a first semiconductor laser device having a first oscillation wavelength band on a semiconductor substrate;
Etching the first stacked structure to form a first semiconductor laser device on a predetermined region of the semiconductor substrate and exposing the semiconductor substrate in a region other than a region where the first semiconductor laser device is formed;
Forming a second laminated structure made of a compound semiconductor layer constituting a second semiconductor laser device having a second oscillation wavelength band different from the first oscillation wavelength band on the entire surface of the substrate;
The second laminated structure is etched to form a second semiconductor laser device on a predetermined region of the semiconductor substrate other than the region where the first semiconductor laser device is formed, and to form the first semiconductor laser device and the second semiconductor laser device. Exposing the semiconductor substrate in an area other than the laser element formation area,
If necessary, the third, fourth,... Having the third, fourth,... Oscillation wavelength bands different from the first and second oscillation wavelength bands and different from each other in the same manner. Forming a semiconductor laser element on a semiconductor substrate. When forming the laminated structure of the compound semiconductor layers constituting the first, second, third, fourth,... Semiconductor laser devices, the optimum growth temperature of the active layer is determined according to the order of the optimum growth temperature of the active layer. 2. The method for manufacturing a multi-wavelength semiconductor laser according to claim 1, wherein each of the semiconductor laser elements is formed in order from a semiconductor laser element having a high level to a semiconductor laser element having a low level. When the optimum growth temperatures of the active layers are the same, it is necessary to form each semiconductor laser device in order from the semiconductor laser device having the highest optimum growth temperature of the cladding layer to the semiconductor laser device according to the order of the optimum growth temperature of the cladding layer. The method for manufacturing a multi-wavelength semiconductor laser according to claim 2, wherein: 2. The method for manufacturing a multi-wavelength semiconductor laser according to claim 1, wherein the substrate has a zinc blend structure. As the semiconductor substrate, a semiconductor substrate having an off angle of more than 0 ° with respect to the {100} plane and not more than 2 ° and turned off in the {0-1-1} plane (A plane) is used. The method for manufacturing a multi-wavelength semiconductor laser according to claim 1. As the semiconductor substrate, a semiconductor substrate which is turned off in the {0-1-1} plane (A plane) at an angle of 2 ° or more and 30 ° or less with respect to the {100} plane is used. A method for manufacturing a multi-wavelength semiconductor laser according to claim 1. The method according to claim 1, wherein a semiconductor substrate made of a group III-V compound semiconductor is used as the semiconductor substrate. 8. The method according to claim 7, wherein a GaAs substrate or an InP substrate is used as the semiconductor substrate. The active layers of the first, second, third, fourth,... Semiconductor laser elements are grown using a material combining at least two elements of Al, Ga, In, N, P, As, and Sb. 2. The method for manufacturing a multi-wavelength semiconductor laser according to claim 1, wherein: 2. The method of manufacturing a multi-wavelength semiconductor laser according to claim 1, wherein a cleaved edge emitting semiconductor laser device is formed as the first, second, third, fourth,... Semiconductor laser device. 2. A multi-wavelength semiconductor laser according to claim 1, wherein vertical cavity surface emitting semiconductor laser elements are formed as the first, second, third, fourth,... Semiconductor laser elements. Method. Forming at least one cleaved end surface emitting semiconductor laser device and the remaining vertical cavity surface emitting semiconductor laser device as the first, second, third, fourth,... Semiconductor laser devices. The method for manufacturing a multi-wavelength semiconductor laser according to claim 1. At least one of the oscillation wavelength bands of the first, second, third, fourth,... Semiconductor laser elements in addition to the first, second, third, fourth,. 2. The method for manufacturing a multi-wavelength semiconductor laser according to claim 1, wherein a light receiving element corresponding to (1) is formed on a semiconductor substrate.

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