JP3681535B2 - Method for manufacturing optical semiconductor element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical semiconductor element, an optical semiconductor element manufacturing method, an optical semiconductor device, an optical disk system, and a magneto-optical disk system, and more particularly, a high-power semiconductor light-emitting element (semiconductor laser) used in the fields of optical communication and optical information processing. And a technology effective when applied to a manufacturing technology of an optical waveguide such as a slab optical waveguide.
[0002]
[Prior art]
A conventional method for manufacturing a semiconductor laser is described in Document 1 “Publication of Japanese Patent Application Laid-Open No. 5-67835”.
[0003]
In the semiconductor laser described in Document 1, zinc (Zn) is intentionally diffused in the GaAs / AlGaAs superlattice structure in order to reduce light absorption at the light output end face. As a result, the energy band gap of the semiconductor in the vicinity of the light output end face is made larger than the portion where Zn is not diffused.
[0004]
Similarly, in a semiconductor device reported in Reference 2 “Publication Patent Publication; Japanese Patent Laid-Open No. 63-146482 (Japanese Patent Publication No. 63-52480)”, zinc (Zn) is contained in the GaAs / AlGaAs superlattice structure. A part that is intentionally thermally diffused is provided, and the energy band gap of the semiconductor in this part is made larger than the part that does not diffuse Zn.
[0005]
Reference 3 “Journal of Applied Physics, Vol. 64, No. 7, October 1, 1988, pp. 3439-3444” intends Si for a GaAs / AlGaAs superlattice structure. The energy band gap of this portion of the semiconductor is made larger than the portion where Si is not diffused.
[0006]
On the other hand, a semiconductor laser as an optical semiconductor element is used as a light source of an optical disk system. FIG. 19 is a schematic diagram showing the arrangement and optical path of an optical system used in a conventional optical disc system.
[0007]
Light 60 emitted from a semiconductor light emitting device 66 using a semiconductor laser passes through a collimating lens 65, a polarizing beam splitter 64, a quarter wavelength (λ / 4) plate 63, and an objective lens 62, and reaches the optical disc 61. .
[0008]
The light reflected by the information recording unit of the optical disc 61 passes through the objective lens 62, the quarter-wave plate 63, the optical path is bent at a right angle by the polarizing beam splitter 64, and passes through the converging lens 67 and the cylindrical lens 68. The light detector 69 is reached.
[0009]
The optical system of such an optical disk system is described in, for example, “Nikkei Electronics” October 10, 1983 issue, P184 (P173 to P194) issued by Nikkei BP. This document describes a semiconductor laser package to which a high frequency module is added as a laser for a video disk.
[0010]
[Problems to be solved by the invention]
In a method of partially diffusing Zn, Si, or the like in a conventional semiconductor superlattice structure and increasing the energy band gap of the semiconductor in that portion, a substance (diffusion source) to be diffused in the semiconductor is used as follows: A process of newly adhering to the substrate in the manufacturing process (impurity deposition process), (2) a process of processing the diffusion source adhering to the substrate into a desired position and size (pattern formation process), and (3) after thermal diffusion Each requires complex steps (diffusion and post-treatment steps) to remove the residue of the diffusion source.
[0011]
On the other hand, in the optical disk system, the light 60 emitted from the semiconductor light emitting element 66 (semiconductor laser) has a high dispersibility. Therefore, in order to condense the light 60 emitted from the semiconductor light emitting element 66 onto the optical disc 61 and use it effectively, several lenses are arranged in the middle of the optical path.
[0012]
An object of the present invention is to provide a simple technique for forming a part of an optical waveguide in a mixed crystal part.
[0013]
Another object of the present invention is to provide a technique for forming a part of an optical waveguide in a mixed crystal part by local heating.
[0014]
Another object of the present invention is to provide a laser without supplying impurities from the outside as a method of forming a mixed crystal portion between semiconductor thin films constituting a semiconductor multilayer film in a part of an optical waveguide formed in the semiconductor multilayer film. The object is to provide a technique for performing light irradiation.
[0015]
Another object of the present invention is to provide an optical semiconductor element and an optical semiconductor device with high optical output.
[0016]
Another object of the present invention is to provide an optical disk system or a magneto-optical disk system in which only one lens is disposed between a light source and an optical disk.
[0017]
The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.
[0018]
[Means for Solving the Problems]
The following is a brief description of an outline of typical inventions disclosed in the present application.
[0019]
(1) An optical semiconductor element having a substrate having a semiconductor multilayer film formed by laminating a plurality of semiconductor thin films having different crystal compositions, wherein a part of the semiconductor multilayer film constitutes an optical waveguide, A part of the optical waveguide is a mixed crystal part having an intermediate composition by melting of the semiconductor thin films.
[0020]
The semiconductor laminated film constitutes an optical waveguide of a semiconductor light emitting device (semiconductor laser), and the mixed crystal portion is provided at one end or both ends of the optical waveguide. The semiconductor laminated film is a superlattice laminated film. The semiconductor laminated film has a structure including at least a combination of GaInP and AlGaInP, a combination of GaAs and AlGaAs, a combination of InGaAs and GaAs, a combination of InGaAs and InP, a combination of GaN and InGaN, and a combination of AlGaN and GaN.
[0021]
Such an optical semiconductor element is manufactured by the following method.
[0022]
A method of manufacturing an optical semiconductor device, comprising: a substrate having a semiconductor multilayer film configured by laminating a plurality of semiconductor thin films having different crystal compositions; and a part of the semiconductor multilayer film constitutes an optical waveguide, After the semiconductor multilayer film is formed on the substrate, a laser beam is irradiated over the entire width of a part of the optical waveguide formation region of the semiconductor multilayer film to mix each semiconductor thin film constituting the semiconductor multilayer film. To form a mixed crystal part.
[0023]
Further, one or two mixed crystal portions are formed, and cleavage is performed so as to cross the mixed crystal portion, so that a semiconductor light emitting element (semiconductor laser) is produced in which the cleavage surface is used as a light emission surface.
[0024]
(2) In the configuration of the means (1), a mixed crystal portion is provided in a part of the optical waveguide, and an optical waveguide (component) for guiding light such as a slab optical waveguide is configured.
[0025]
(3) In the optical semiconductor element having the constitution of the means (1) or means (2), an element (for example, Zn) that acts to mix the crystal composition through the bonding surface of each semiconductor thin film in the mixed crystal portion. , Si, etc.) is contained in an amount larger than the amount of mixed crystals between the semiconductor thin films constituting the semiconductor laminated film.
[0026]
Such an optical semiconductor element is manufactured by the following method.
[0027]
In the method of manufacturing an optical semiconductor element having the configuration of the means (1), a gas containing an impurity (the element) such as Zn or Si is supplied for a desired time to at least the semiconductor thin film portion irradiated with the laser light during the laser light irradiation. .
[0028]
(4) A package having a sealed structure, an optical semiconductor element incorporated in the package, and an optical transmission unit that is optically connected to an optical waveguide end of the optical semiconductor element and transmits light inside and outside the package. The optical semiconductor device has any one of the means (1) to the means (3).
[0029]
(5) In an optical disk system using light for recording and reading, the light source for emitting the light is constituted by the optical semiconductor element of the means (1) or (3) or the optical semiconductor device of the means (4). In addition, only one light focusing lens is disposed in the middle of the optical path between the light source and the optical disk.
[0030]
(6) A magneto-optical disk system using light for recording and reading, wherein the light source for emitting light is the optical semiconductor element of the means (1) or (3) or the optical semiconductor device of the means (4) In the middle of the optical path between the light source and the optical disc, only one light focusing lens is provided.
[0031]
(7) A method of manufacturing an optical semiconductor device having any one of the means (1) to (3), wherein light is concentrated at the center of the surface of the substrate on the region where the mixed crystal part is formed. A lens-shaped insulating film that generates an effect is formed, and then the lens-shaped insulating film portion is irradiated with laser light to form the mixed crystal portion.
[0032]
(8) In the method of manufacturing an optical semiconductor element having any one of the means (1) to (3), an insulating film is formed on the semiconductor stacked film directly or via a semiconductor layer, The mixed crystal part is formed while irradiating a laser beam on the insulating film to diffuse impurities (the element) contained in the insulating film into the semiconductor laminated film. The semiconductor layer is a ridge extending along the optical waveguide.
[0033]
According to the above (1), (a) the surface of the substrate is irradiated with laser light to locally heat and melt the semiconductor laminated film (superlattice laminated film), and the composition of the superlattice layer has a desired structure (each semiconductor Since the mixed crystal part is formed by changing to an intermediate composition between thin films), the energy band gap of the mixed crystal part becomes larger than the energy band gap of other optical waveguide parts, and the light in the mixed crystal part Loss due to absorption of Therefore, in the structure in which the mixed crystal portion is provided on one surface or both surfaces of the semiconductor laser, the laser light emission surface is hardly deteriorated and the life of the semiconductor laser is extended. This also achieves higher output of the semiconductor laser.
[0034]
(B) The formation of the mixed crystal part can be performed only by laser beam irradiation without supplying an element that acts to mix crystal composition such as Zn and Si as in the prior art, The conventional impurity deposition processing step, pattern formation step, diffusion and post-processing step are not required, and the mixed crystal portion can be formed with high accuracy and high yield at low cost. Therefore, the manufacturing cost of the semiconductor laser can be reduced.
[0035]
According to (2), since the mixed crystal portion having a large energy band gap is provided in a part of the optical waveguide, light absorption does not occur in the mixed crystal portion of the optical waveguide, and the optical waveguide Reduction of optical loss can be achieved.
[0036]
According to (3), the mixed crystallizing unit supplies a substance containing a diffusion source such as Zn or Si to a desired region on the surface of the semiconductor substrate in a gaseous state while locally irradiating the region with laser light irradiation. Since it is formed by heating, it has a feature that a diffusion substance supplying method is easier than a conventional method in which a film containing a diffusion source such as Zn or Si is attached to the surface of a semiconductor substrate.
[0037]
According to the above (4), since the optical semiconductor device incorporates the semiconductor light emitting element (semiconductor laser) having a structure in which the mixed crystal portion is provided on one or both sides of the emission surface, the optical semiconductor device has a long lifetime. Or higher output can be achieved.
[0038]
According to the above (5), since a high-power optical semiconductor element or optical semiconductor device is used as the light source in the optical disk system, a single light convergence that wastes part of the laser light emitted from the semiconductor laser element. Even in the configuration of the optical lens, recording and reading can be reliably performed in the information recording unit of the optical disk. In particular, in the configuration in which the lens is placed close to the optical disc, the diameter of the spot light on the optical disc surface can be reduced, and the capacity of information recording can be increased.
[0039]
According to the above (6), in the magneto-optical disk system, since a high-output optical semiconductor element or optical semiconductor device is used as the light source, a single part of the laser light emitted from the semiconductor laser element is wasted. Even with the configuration of the light converging lens, recording and reading by the information recording unit of the optical disk can be performed reliably. In particular, in the configuration in which the lens is placed close to the optical disc, the diameter of the spot light on the optical disc surface can be reduced, and the capacity of information recording can be increased.
[0040]
According to the above (7), in the formation of the mixed crystal part, the lens-like insulating film that generates the light condensing effect that the center rises on the surface of the substrate on the region where the mixed crystal part is formed is formed. Since the mixed crystal portion is formed by irradiating the lens-like insulating film portion with laser light, the lens-like insulating film can focus the laser light on a predetermined semiconductor laminated film portion, and with high accuracy. A mixed crystal part can be formed.
[0041]
According to (8), in forming the mixed crystal part, after forming an insulating film directly or via a semiconductor layer on the semiconductor laminated film, the insulating film is irradiated with laser light from the insulating film. Since the mixed crystal portion is formed while diffusing impurities (the elements) contained in the semiconductor laminated film, mixed crystallization by laser light and mixed crystallization by impurity diffusion can be performed at the same time, and high-precision mixing is achieved. A crystallization part can be formed. In particular, when the semiconductor layer is a ridge extending along the optical waveguide, the ridge can be used as a guide for laser light irradiation, and high accuracy of the formation position of the mixed crystal portion can be achieved. .
[0042]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments and examples of the invention, and the repetitive description thereof is omitted.
[0043]
(Embodiment 1)
FIGS. 1 to 5 are diagrams relating to an optical semiconductor element (semiconductor laser element) and a method for manufacturing the same according to an embodiment (Embodiment 1) of the present invention.
[0044]
FIG. 1 is a schematic view of forming a mixed crystal part by locally heating and melting a part of a portion that becomes an optical waveguide by laser light irradiation.
[0045]
In FIG. 1, a substrate 1 is a GaAs substrate, for example, and a superlattice laminated film (semiconductor laminated film) 2 made of GaInP / AlGaInP is formed on this substrate by a crystal growth method such as MOCVD or MBE.
[0046]
Here, the GaInP / AlGaInP superlattice layer has a GaInP thickness of about 5 nm and an AlGaInP thickness of about 4 nm, and has a structure in which GaInP and AlGaInP are alternately repeated to form a well layer of three layers. The structure is sandwiched between AlGaInP 3 and 4 having a larger energy gap than the superlattice layer 2. Laser light 15 was irradiated perpendicularly to the substrate surface from the substrate surface including the superlattice layer 2.
[0047]
Here, the spot size of the laser beam 15 was 1 mm linearly at a scanning speed of 1 μm / s at an irradiation power of 100 mW.
[0048]
In FIG. 2, the cross section of the laser beam irradiation part is typically shown. In this figure, the melted part 5 formed by laser irradiation has an intermediate composition between GaInP and AlGaInP, and the energy band gap is increased by about 80 meV compared to the state before melting. Turned out to be.
[0049]
Example 1
Next, an example in which the present invention is applied to a semiconductor laser device manufacturing technique will be described. In the first embodiment, an example in which the front emission surface portion of the semiconductor laser element is a mixed crystal portion will be described.
[0050]
3A and 3B are schematic perspective views showing the structure of the semiconductor laser device. FIG. 4A is a cross-sectional view taken along line BB in FIG. 3, and FIG. 4B appears in a cross section taken along line BB. 5 is a graph showing an energy band gap distribution of the active layer.
[0051]
The semiconductor laser element 20 has a structure as shown in FIG. In FIG. 3, each part includes a GaAs substrate 1, an n-type AlGaInP clad layer 22, an active layer 23, a p-type AlGaInP clad layer 24, an etching stop layer 25, an n-type GaAs block layer 27, a p-type GaAs buried layer 26, and a ridge 8. , And a mixed crystal part 9 at the element end face.
[0052]
The active layer 23 has an MQW structure (superlattice laminated film: semiconductor laminated film) made of GaInP / AlGaInP quantum wells as described above.
[0053]
The ridge 8 is formed by etching both sides of the p-type AlGaInP cladding layer 42.
[0054]
The mixed crystallizing part 9 is a part obtained by partially melting an MQW structure composed of GaInP / AlGaInP quantum wells with laser light and averaging the crystal composition, as will be described later. This is a region in which the energy band gap is larger than the portion that is not.
[0055]
In the mixed crystal part 9, the energy band gap of the active layer is large as shown in FIG. In other words, the crystallized portion 9 has an intermediate composition of GaInP and AlGaInP, and the energy band gap is increased by about 80 meV from 1.907 eV at the portion not melted by laser light irradiation. .980 eV.
[0056]
The semiconductor laser element 20 is transparent to light emitted from the inside of the element due to the presence of the mixed crystal part 9 at the element end face.
[0057]
When a current was passed through the fabricated device and the optical output was tested, the device was continuously operated with an optical output of 50 mW, and a lifetime of 4000 hours could be confirmed. On the other hand, in the element in which the mixed crystal portion is not formed, the element was instantly deteriorated at a light output of 50 mW. Therefore, in an element in which a mixed crystal part is introduced, heat generation due to light absorption at the end face of the mixed crystal part is suppressed during element operation, and deterioration of the element due to heat generation at the end face can be prevented.
[0058]
The semiconductor laser device 20 has a crystal defect density of 10² -10^Three cm ~²During the production, heat treatment is performed at 500 ° C. for 1 hour (hydrogen atmosphere) as follows.
[0059]
Next, a method for manufacturing the semiconductor laser element 20 will be described with reference to FIGS.
[0060]
First, a substrate 1 on which a mixed crystal part 9 as shown in FIG. This substrate 1 is the substrate 1 formed by the method by laser beam irradiation shown in FIG.
[0061]
That is, the substrate 1 is made of a GaAs substrate, and an n-type AlGaInP cladding layer 22, an active layer 23, a p-type AlGaInP cladding layer 24, an etching stop layer 25, and a p-type AlGaInP cladding layer 42 are sequentially formed on the upper surface of the substrate 1. ing. The active layer 23 has an MQW structure composed of GaInP / AlGaInP quantum wells having three well layers as described above.
[0062]
Next, as shown in FIG.₂After the stripe-shaped mask 16 is formed of a film or the like, the p-type AlGaInP cladding layer 42 is partially removed up to the etching stop layer 25 using the mask 16 as an etching mask to form the stripe-shaped ridge 8.
[0063]
Next, as shown in FIG. 5B, an n-type GaAs block layer 27 is buried and formed on the etching stopper layer 25 exposed by etching.
[0064]
Next, the mask 16 is removed, and a p-type GaAs buried layer 26 is formed on the ridge 8 and the n-type GaAs block layer 27 (see FIG. 5C).
[0065]
Since the active layer 23 portion under the ridge 8 becomes an optical waveguide, the mixed crystal portion 9 is formed so as to cross the entire width of a part of the optical waveguide.
[0066]
Next, electrodes 28 and 29 are respectively formed on the front and back surfaces of the substrate 1, and then the substrate 1 is cleaved so as to include the mixed crystal portion 9. The two-dot chain line portion in FIG. 5C is a portion to be cleaved.
[0067]
Next, SiN / SiO having a reflectance of 19% is formed on the front emission surface of the semiconductor laser element 20.₂The protective film 30 and the SiN / SiO protective film 31 having a reflectance of 90% are formed on the rear emission surface, and the semiconductor laser device 20 is manufactured.
[0068]
Further, the crystal defect density of the optical waveguide portion is set to 10² -10^Three cm ~²Heat treatment is performed at 500 ° C. for 1 hour (hydrogen atmosphere) so as to be as follows.
[0069]
According to the semiconductor laser device 20 according to the first embodiment, the optical output becomes 50 to 70 mW when the applied voltage is 2.5 to 3.5 V and the current is 120 to 180 mA. In a conventional product without a mixed crystal part, an optical output is 20 to 30 mW at an applied voltage of 3 to 4 V and a current of 150 to 300 mA. It can be seen that the semiconductor laser device 20 of the first embodiment can obtain an optical output that is twice or more that of the conventional one at an applied voltage and current that is comparable or lower than those of the conventional one.
[0070]
The semiconductor laser device 20 of the first embodiment is used by being incorporated in a sealed container (package) as shown in FIG. 6, for example.
[0071]
FIG. 6 is a perspective view of a semiconductor laser device (optical semiconductor device) with a part cut away.
[0072]
The semiconductor laser device (optical semiconductor device) 35 includes a package main body 36 that is a main component of the assembly, and a lid 37 that is attached to the surface side of the package main body 36. The package is formed by a package body 36 and a lid body 37.
[0073]
The package body 36 is made of a circular metal plate having a thickness of several millimeters, and a copper heat sink 38 is fixed to the part off the center of the surface with a brazing material or the like.
[0074]
A submount 39 made of silicon or the like is fixed to the tip side of the side surface (front surface) facing the center of the package body 36 of the heat sink 38.
[0075]
The semiconductor laser element 20 is fixed to the submount 39 via a conductive bonding material.
[0076]
A light receiving element 40 for monitoring laser light emitted from the rear emission surface of the semiconductor laser element 20 is fixed at the center of the package body 36. The light receiving element 40 is fixed to an inclined surface so that the laser beam does not reach the emission surface of the semiconductor laser element 20.
[0077]
Three leads 41 are fixed to the package body 36. The two leads 41 are fixed to the package body 36 through the insulator 47 in a penetrating manner. The remaining one lead 41 is fixed to the back surface of the package body 36 in a butted manner.
[0078]
The tip of the lead 41 protruding to the surface side of the package body 36 and the electrode on the upper surface of the semiconductor laser element 20 and the electrode on the upper surface of the light receiving element 40 are electrically connected by a conductive wire 43. The electrode on the back surface of the light receiving element 40 is electrically connected to one lead 41 through the package body 36. The electrode on the back surface of the semiconductor laser element 20 is electrically connected to one lead 41 via the submount 39, the heat sink 38 and the package body 36.
[0079]
On the other hand, the lid body 37 has a cap structure and has a light transmission window 45 through which the laser light 44 is transmitted. The light transmission window 45 is formed by overlapping and fixing a transparent glass plate 46 on a hole provided in the lid 37.
[0080]
In such an optical semiconductor device 35, since the semiconductor laser element 20 of the first embodiment is incorporated, the optical output is as high as 50 to 70 mW.
[0081]
According to the first embodiment and the first embodiment, the following effects are obtained.
[0082]
(1) The surface of the substrate 1 is irradiated with a laser beam 15 to locally heat and melt the semiconductor laminated film (superlattice laminated film) 2 to change the composition of the superlattice layer to a desired structure (intermediate between each semiconductor thin film). Therefore, the energy band gap of the mixed crystal portion 9 becomes larger than the energy band gap of the other optical waveguide portions, and the light in the mixed crystal portion 9 is changed. No loss due to absorption occurs. Therefore, in the structure in which the mixed crystal portion 9 is provided on the front emission surface of one surface of the semiconductor laser element 20, the front emission surface is hardly deteriorated and the life of the semiconductor laser (semiconductor laser element 20) is extended. This also achieves higher output of the semiconductor laser.
[0083]
(2) The formation of the mixed crystal portion 9 can be performed only by laser beam irradiation without supplying an element that acts to mix crystal composition such as Zn or Si as in the prior art. Thus, the conventional impurity deposition processing step, pattern formation step, diffusion and post-processing step are not required, and the mixed crystal portion can be formed with high accuracy and high yield at low cost. Therefore, the manufacturing cost of the semiconductor laser (semiconductor laser element 20) can be reduced.
[0084]
(Example 2)
The semiconductor laser device 20 of the second embodiment is an example in which the mixed crystal portion 9 is formed on the emission surface portions before and after the semiconductor laser device 20.
[0085]
By forming the mixed crystal portions 9 on both end faces of the semiconductor laser device 20, the light output level of the device is further increased by 50 to 80% as compared with an element in which the mixed crystal portions are provided only on one end face. I was able to.
[0086]
(Example 3)
In the third embodiment, an example will be described in which a mixed crystal portion is formed by laser beam irradiation after the ridge pattern is formed in the first embodiment.
[0087]
In FIG. 12, a ridge 8 is formed on an epitaxial film for manufacturing a semiconductor laser device by photolithography and etching, and then the surface is covered with an insulating film 85 such as SiO 2 or SiN. Thereafter, the laser beam 15 is irradiated from outside the substrate to a desired location of the ridge 8 and heated. A portion indicated by a two-dot chain line in the figure is a region irradiated with the laser light 15.
[0088]
In the crystal part irradiated with the laser beam 15, an impurity element such as zinc previously doped in the crystal diffuses to cause mixed crystal in the heterojunction portion or is supplied by the laser beam 15. The heat itself is a phenomenon in which the heterojunction portion melts, and the energy band gap of that portion becomes larger than before the laser beam irradiation.
[0089]
This process is characterized in that the laser beam irradiation position on the substrate is accurately aligned by computer control, and is performed after the ridge pattern is formed. That is, as shown in FIGS. 1 and 3, the formation accuracy of the ridge pattern is improved as compared with the case where the ridge 8 is formed after the melted portion 5 and the mixed crystal portion 9 are formed. Therefore, the device manufacturing yield is greatly improved.
[0090]
In this example, Si contained in the insulating film 85 can also be diffused into the mixed crystal part 9.
[0091]
Accordingly, mixed crystallization by the laser beam 15 and mixed crystallization by impurity diffusion can be performed at the same time, and the mixed crystallization portion 9 can be formed with high accuracy.
[0092]
Further, when the laser beam 15 is irradiated, the ridge 8 can be used as a guide for the laser beam irradiation, so that the formation position of the mixed crystal portion can be increased.
[0093]
(Embodiment 2)
FIG. 9 shows a semiconductor laser device according to another embodiment (Embodiment 2) of the present invention, in which a semiconductor superlattice laminated on a substrate is locally mixed using laser light irradiation and impurity diffusion. It is a typical perspective view which shows a state. FIG. 10 is an explanatory view in a cross section taken along the line CC of FIG.
[0094]
In the first embodiment and the first embodiment, only the laser beam 15 is irradiated on the surface of the substrate 1 and the mixed crystal portion 9 is formed by heating and melting the irradiated portion. However, in the second embodiment, the laser beam 15 is irradiated with the laser beam 15. While irradiating, a gaseous diffusion material was supplied to the irradiation part.
[0095]
As shown in FIG. 9, the diffusion material is controlled by using a pipe 7 so as to be supplied locally to the laser beam irradiation unit. The diffusion material to be supplied includes gaseous compounds such as zinc (Zn), beryllium (Be), and silicon (Si), which are elements acting to mix the crystal composition from the heterojunction surface of the GaInP / AlGaInP superlattice laminated film. Was used.
[0096]
In the gaseous compound of Zn, for example, dimethylzinc ((CH3) 2Zn), Be is dimethylberyllium ((CH3) 2Be), and silicon is monosilane (SiH4).
[0097]
According to the method of Embodiment 2, when the supply amount of dimethylzinc is about 1 cc / min and the power of the laser beam 15 to be irradiated is 50 mW, which is half of that in Embodiment 1, the superconductivity of GaInP / AlGaInP is increased. It has been found that the composition of the lattice laminated film 2 is mixed from the heterojunction interface.
[0098]
The diffusion unit 6 shown in FIG. 10 corresponds to this region. In this portion, Zn (an element that acts to mix the crystal composition) supplied from the outside during the laser light diffusion diffuses from the surface of the crystal substrate to the inside, and the crystal composition at the heterojunction interface of the superlattice multilayer film 2 Promote mixing.
[0099]
In the mixed crystallization portion 9 according to the second embodiment, elements (for example, Zn, Si, etc.) that act to mix the crystal composition through the bonding surfaces of the semiconductor thin films are mutually connected to the semiconductor thin films. More than the amount of mixed crystals.
[0100]
When the photoluminescence of the diffusion part 6 (mixed crystal part 9) was examined, it was found that the emission peak energy was shifted to the short wavelength side by about 70 meV compared to the region other than the diffusion part.
[0101]
According to the second embodiment, the mixed crystal unit 9 supplies a substance containing a diffusion source such as Zn or Si to a desired region on the surface of the semiconductor substrate in a gaseous state while locally irradiating the region with laser light irradiation. Therefore, the diffusion material supply method is easier than the conventional method in which a film containing a diffusion source such as Zn or Si is deposited on the surface of the semiconductor substrate.
[0102]
(Embodiment 3)
11 to 13 are diagrams relating to the manufacture of a semiconductor laser device according to another embodiment (Embodiment 3) of the present invention. FIG. 11 is a schematic perspective view showing a state in which a semiconductor superlattice laminated on a substrate is focused on a laser beam by a lens-like insulating film formed on the substrate and locally mixed, and FIG. 12 is a diagram of FIG. FIG. 13 is a schematic sectional view showing a method of forming a lens-like insulating film on a substrate.
[0103]
In the third embodiment, a long lens-like insulating film (lens-like insulating film 81) having an effect of condensing light is formed on the surface of the substrate 1 that is irradiated with the laser light 15. The laser beam 15 irradiated to the substrate surface is narrowed down to increase the energy band gap by local melting of the GaInP / AlGaInP superlattice laminated film 2.
[0104]
FIG. 12 shows SiO 2 in advance.₂On the surface of the AlGaInP film, the laser beam 15 is irradiated onto the surface of the substrate on which the long lens-like insulating film 81 made of an insulating film or the like is formed. Fig. 6 schematically shows the state of irradiation with a large light density. Here, the long lens-like insulating film 81 is formed of, for example, SiO using a shadow mask 82 as shown in FIG.₂The mask opening 83 can be formed at a specific location on the substrate 1 by the CVD method or the like.
[0105]
In FIG. 12, when the dimension of the mask opening 83 is about 10 μm and the distance between the shadow mask and the substrate surface is 10 μm, the base of the long lens-like insulating film pattern formed by CVD becomes about 30 μm. Further, if the thickest portion of the insulating film is about 1 μm, the lens effect can be caused, and the molten portion 5 (mixed crystal portion 9) can be formed with high accuracy.
[0106]
In the third embodiment shown in FIGS. 11 and 12, the AlGaInP crystal portion is protected by an insulating film, and it is also a great feature that phosphorus atoms can be prevented from detaching from the crystal surface, that is, deterioration of the crystal surface can be prevented. .
[0107]
(Embodiment 4)
FIG. 14 is a schematic diagram showing a pickup section of an optical disc system according to another embodiment (Embodiment 4) of the present invention.
[0108]
In the fourth embodiment, an example in which a semiconductor laser device according to the present invention is incorporated as a light source of an optical disk system will be described.
[0109]
FIG. 14 is a schematic diagram showing the arrangement and optical paths of the optical system used in the optical disc system according to the present invention.
[0110]
The light 60 emitted from the light source (semiconductor light emitting element 66) passes through the collimating lens 65, the polarizing beam splitter 64, and the quarter wavelength (λ / 4) plate 63 and reaches the optical disc 61.
[0111]
The light reflected by the information recording unit of the optical disc 61 passes through the quarter-wave plate 63, the optical path is bent at a right angle by the polarizing beam splitter 64, passes through the converging lens 67 and the cylindrical lens 68, and then the photodetector. Reach 69.
[0112]
As the semiconductor light emitting device 66, the high output semiconductor laser device 20 having an optical output of 50 to 70 mW according to each of the embodiments of the present invention is used. The semiconductor laser element 20 is used, for example, as an optical semiconductor device 35 as shown in FIG.
[0113]
According to the optical disk system of the fourth embodiment, since the high-power semiconductor laser device 20 is used as the light source, the configuration of a single light converging lens that wastes part of the laser light emitted from the semiconductor laser device. However, recording and reading can be reliably performed in the information recording unit of the optical disk.
[0114]
That is, by omitting even one lens in the middle of the optical path, the assembly adjustment of the optical system is facilitated, which contributes to shortening the system manufacturing time and manufacturing cost.
[0115]
(Embodiment 5)
FIG. 15 is a schematic diagram showing a pickup section of an optical disc system in another embodiment (Embodiment 5) of the present invention.
[0116]
In the fifth embodiment, the collimating lens 65 is arranged on the optical disc 61 side in the optical disc system of the fourth embodiment. Thus, in the configuration in which the lens (collimator lens 65) is placed close to the optical disc 61, the diameter of the spot light on the optical disc surface can be reduced, and the capacity of information recording can be increased. This also makes it possible to reduce the size of the optical disc 61.
[0117]
(Embodiment 6)
FIG. 16 is a schematic diagram showing a pickup unit of an optical disc system according to another embodiment (sixth embodiment) of the present invention.
[0118]
The optical disk system of the sixth embodiment has a structure in which the lens 70 is bonded to the surface of the quarter wavelength (λ / 4) plate 63 on the optical disk 61 side, so that the assembly adjustment of the optical system is facilitated. Is possible.
[0119]
Further, the assembly space is reduced, and the optical disk system can be miniaturized.
[0120]
(Embodiment 7)
FIG. 17 is a schematic diagram showing a pickup section of a magneto-optical disk system in another embodiment (Embodiment 7) of the present invention.
[0121]
In the fourth to sixth embodiments, the application example to the optical system of the optical disk apparatus having the unevenness on the recording surface has been described. However, the present invention can be similarly applied to a magneto-optical disk using a magnetic substance as a recording medium.
[0122]
The light 60 emitted from the semiconductor light emitting element 66 passes through the polarization beam splitter 64 and the objective lens 62 and reaches the magneto-optical disk recording surface 90 of the magneto-optical disk 93 disk 61.
[0123]
Further, the light reflected by the magneto-optical disk recording surface 90 passes through the objective lens 62, the optical path is bent at a right angle by the polarization beam splitter 64, and is guided to a photodetector (not shown).
[0124]
At the time of writing, high-power light 60 is applied to the magneto-optical disk recording surface 90, and the magneto-optical disk recording surface 90 is heated. In this state, the direction of magnetization changes depending on the direction of the current applied to the coil 91, and information is recorded. At the time of reading, the direction of magnetization (phase change) is detected by the difference in the amount of reflected light on the magneto-optical disk recording surface 90 with low light output.
[0125]
(Embodiment 8)
FIG. 18 is a schematic cross-sectional view showing an optical waveguide which is another embodiment (Embodiment 8) of the present invention.
[0126]
In the eighth embodiment, the present invention is applied to an optical waveguide 95 such as a slab optical waveguide.
[0127]
As shown in FIG. 18, a semiconductor laminated film is formed between InP14 and InP13 on the upper surface of the substrate 1 made of GaAs. In this example, unlike the semiconductor laser device manufacturing, the semiconductor laminated film does not necessarily need to be a superlattice laminated film. For example, GaInPAs / GaInAs12 is formed as the semiconductor laminated film.
[0128]
This GaInPAs / GaInAs12 constitutes a laminated film planar waveguide.
[0129]
Therefore, by the same method as in the first embodiment, the laser beam 15 is irradiated from the upper surface of the substrate 1 to locally heat and melt to form the melted portion 5 (mixed crystal portion 9) mixed crystal portion. To do.
[0130]
In the optical waveguide 95 of the eighth embodiment, in the mixed crystal part 9, a part of the optical waveguide composed of GaInPAs / GaInAs12 has a larger energy band gap than the other optical waveguide parts, so that it is in a transparent region. Thus, since loss of light in this region can be prevented, the optical waveguide 95 with small light loss can be manufactured.
[0131]
For the optical waveguide 95 of the first embodiment, the methods of the respective embodiments and examples in the case of manufacturing the semiconductor laser element can be applied.
[0132]
Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. For example, in the above-described embodiments and examples, the semiconductor crystal (semiconductor laminated film) has been described as being an AlGaInP / GaInP heterojunction, but AlGaAs / GaAs, GaN / AlGaN, GaN / InGaN, and InGaAs / GaAs heterojunction. Needless to say, the present invention can also be applied to systems such as bonding.
[0133]
【The invention's effect】
The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
[0134]
(1) According to the present invention, a mixed crystal part having an increased energy band gap can be formed in a part of the optical waveguide by a simpler manufacturing method than in the prior art.
[0135]
(2) As a result, high output of the semiconductor laser can be easily achieved.
[0136]
(3) It is also possible to provide an optical waveguide with little light loss.
[0137]
(4) Further, by using the semiconductor laser according to the present invention, the optical system of the optical disk system and the magneto-optical disk system can be simplified, and the assembly process of the optical disk system and the magneto-optical disk system can be shortened and the cost can be reduced. Can be achieved.
[Brief description of the drawings]
FIG. 1 shows a state where a semiconductor superlattice stacked on a substrate is locally mixed by laser light irradiation in the manufacture of an optical semiconductor device (semiconductor laser device) according to an embodiment (embodiment 1) of the present invention. It is a typical perspective view which shows.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a schematic perspective view showing the structure of a semiconductor laser device according to Example 1 of the present invention.
4 is a cross-sectional view taken along line BB in FIG. 3 and a graph showing an energy band gap distribution of an active layer appearing in the cross section.
5 is a schematic cross-sectional view showing a substrate and the like in each step in manufacturing a semiconductor laser device of Example 1. FIG.
6 is a perspective view with a part cut away showing a semiconductor laser device incorporating the semiconductor laser element of Example 1. FIG.
7 is a schematic cross-sectional view of a semiconductor laser device according to Example 2. FIG.
8 is a schematic perspective view showing a mixed crystallization method in manufacturing a semiconductor laser device of Example 3. FIG.
FIG. 9 shows a semiconductor laser device according to another embodiment (embodiment 2) of the present invention, in which a semiconductor superlattice laminated on a substrate is locally mixed using laser light irradiation and impurity diffusion. It is a typical perspective view which shows the state to do.
10 is an explanatory diagram in a cross section taken along the line CC of FIG. 9;
FIG. 11 is a diagram illustrating a method of manufacturing a semiconductor laser device according to another embodiment (embodiment 3) of the present invention; condensing laser light with a lens-shaped insulating film formed on a substrate with a semiconductor superlattice laminated on the substrate; FIG. 6 is a schematic perspective view showing a state in which a mixed crystal is locally formed.
12 is an explanatory diagram in a cross section taken along line DD of FIG.
FIG. 13 is a schematic cross-sectional view showing a method for forming a lenticular insulating film on a substrate in the third embodiment.
FIG. 14 is a schematic diagram showing a pickup section of an optical disc system in another embodiment (Embodiment 4) of the present invention.
FIG. 15 is a schematic diagram showing a pickup section of an optical disc system in another embodiment (Embodiment 5) of the present invention.
FIG. 16 is a schematic diagram showing a pickup section of an optical disc system in another embodiment (Embodiment 6) of the present invention.
FIG. 17 is a schematic diagram showing a pickup unit of a magneto-optical disk system in another embodiment (Embodiment 7) of the present invention.
FIG. 18 is a schematic cross-sectional view showing an optical waveguide which is another embodiment (Embodiment 8) of the present invention.
FIG. 19 is a schematic diagram showing a pickup unit of a conventional optical disc system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... GaInP / AlGaInP superlattice laminated film (semiconductor laminated film), 3, 4 ... AlGaInP, 5 ... Melting part, 6 ... Diffusion part, 7 ... Pipe, 8 ... Ridge, 9 ... Mixed crystallizing part, 12 ... GaInPAs / GaInAs, 13, 14 ... InP, 15 ... laser light, 16 ... mask, 20 ... semiconductor laser element, 22 ... n-type AlGaInP clad layer, 23 ... active layer, 24 ... p-type AlGaInP clad layer, 25 ... Etching stop layer, 26 ... p-type GaAs buried layer, 27 ... n-type GaAs block layer, 30 ... SiN / SiO₂Protective film, 31 ... SiN / SiO protective film, 35 ... optical semiconductor device, 36 ... package body, 37 ... lid body, 38 ... heat sink, 39 ... submount, 40 ... light receiving element, 41 ... lead, 42 ... p-type AlGaInP Cladding layer, 43 ... wire, 44 ... laser light, 45 ... light transmission window, 46 ... transparent glass plate, 47 ... insulator, 61 ... optical disc, 62 ... objective lens, 63 ... quarter wavelength plate, 64 ... polarization Beam splitter, 65 ... collimating lens, 66 ... semiconductor light emitting element, 67 ... converging lens, 68 ... cylindrical lens, 69 ... photodetector, 70 ... lens, 81 ... long lens-like insulating film, 82 ... shadow mask, 83 ... mask Opening, 85 ... insulating film, 86 ... buffer layer, 87 ... cap layer, 90 ... magneto-optical disk recording surface, 91 ... coil, 93 ... magneto-optical disk , 95 ... optical waveguide.

Claims (1)

Having a substrate on which a semiconductor thin film crystal composition are different from each other has a semiconductor multilayer film constituted by a plurality of stacked, Ri manufacturing method der of the optical semiconductor element in which a part of the semiconductor multilayer film constituting the optical waveguide, wherein After the semiconductor multilayer film is formed on the substrate, a laser beam is irradiated over the entire width of a part of the optical waveguide formation region of the semiconductor multilayer film to mix each semiconductor thin film constituting the semiconductor multilayer film. a method for manufacturing an optical semiconductor device that form a disordered portion by the lenticular insulating film to generate a light condensing effect of the middle bulges on the surface of the substrate in the region forming the disordered portion formed, the manufacturing method of subsequent said lenticular insulating film portion to the optical semiconductor element you characterized in that by irradiating a laser beam to form the disordered portion.

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