JPH09321380A - Semiconductor light emitting device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a leak effectively, even if solder creeps up at the time of die bonding to a fitting part by soldering, without increasing the number of manufacturing processes. SOLUTION: On a substrate 1, a laminated semiconductor layer having at least a first conductivity type clad layer 3, an active layer 4, and a second conductivity type clad layer 5 is formed, and an insulating protective film 15 is formed crossing over from the side surface having the light emitting end surface of this laminated semiconductor layer to the side surfaces not having any light emitting end surfaces, and the side surfaces not having any light emitting end surfaces from inverse messa inclined surfaces inclined so as to face reach other toward the substrate 1 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device and a method for manufacturing the same.

[0002]

2. Description of the Related Art A semiconductor light emitting device such as a semiconductor laser has a laminated semiconductor layer in which semiconductor layers such as a first cladding layer, an active layer, and a second cladding layer are epitaxially grown and laminated on a semiconductor substrate. One electrode layer is formed on top.

Usually, the side surfaces on which both end surfaces of the Fabry-Perot resonator for causing the laser oscillation of this semiconductor laser, that is, the light emitting end surface are formed, have required optical characteristics and are protected by, for example, SiN. The protective film is applied. The insulating protective film is also deposited on the other side surface at the same time, but it is finally removed in the process of manufacturing the semiconductor laser.

On the other hand, the thickness of the above-mentioned laminated semiconductor layer in the semiconductor laser is much smaller than that of the semiconductor substrate, and the distance between the active layer and the electrode layer on the laminated semiconductor layer is several or several. Since the thickness is about ten and several μm, the semiconductor laser is die-bonded to the header or the heat sink with solder in consideration of the heat radiation effect from the laser oscillation part. Made in. However, in this case, since the position of the active layer is close to the die bond part, the solder easily reaches the active layer by crawling along the side surface of the semiconductor laser, causing a leak and deteriorating the characteristics. Or, defective products will be generated.

Further, in order to facilitate understanding of the problems in the conventional semiconductor light emitting device, an example of this type of conventional semiconductor laser and a method of manufacturing the same will be described. First, FIG.
As shown in FIG. 1, a substrate 1, for example, a substrate 1 made of an n-type GaAs substrate, is provided with a buffer layer 2, n made of n-type GaAs.
Type Al _x Ga _1-x As clad layer 3, Al _y G
a _1-y As (x> y) active layer 4, p-type Al _X G
A laminated semiconductor layer 8 is formed by sequentially epitaxially growing a clad layer 5 made of a _{1- x} As and a cap layer 6 made of p-type GaAs, and a mask layer 7 for selective epitaxial growth, for example, a SiO ₂ layer is formed on the laminated semiconductor layer 8.

As shown in FIG. 3, the mask layer 7 is subjected to pattern etching by, for example, photolithography,
The mask layer 7 has a width corresponding to the resonator width to be finally obtained, and is formed into a stripe pattern in which the mask layers 7 are arranged in parallel while maintaining a required space, and the cap layer 6 other than the stripe pattern is exposed to the outside. A current confinement groove 9 having a depth reaching the cladding layer 5 is formed by etching, and a stripe-shaped ridge 10 is formed between each adjacent current confinement grooves 9.

As shown in FIG. 4, the current confinement groove 9 which is not covered with the stripe-shaped mask layer 7 and which is exposed to the outside is exposed.
A current confinement layer 9 made of n-type GaAs is formed therein by a selective CVD (Chemical Vapor Deposition) method.

As shown in FIG. 5, the mask layer 7 is entirely removed from the side where the mask layer 7 is formed to remove the mask layer 7, and the surface is planarized.

As shown in FIG. 10, one electrode layer 11 which makes ohmic contact is entirely formed on the cap layer 6, and the electrode layer 1 is provided between the striped ridges 10.
A separation groove 13 for separating the 1 and the laminated semiconductor layer 8 for each semiconductor light emitting device is formed to form a stripe mesa 14. Then, as indicated by chain lines a ₁ , a ₂ ... In FIG. 10, a width corresponding to a resonator length finally formed on the substrate 1 having the laminated semiconductor layer 8 across the stripe-shaped mesas 14. The semiconductor bar 12 in which a plurality of target semiconductor light-emitting devices are arranged in parallel is obtained by cutting into semiconductor chips as shown in FIG.

Thereafter, as shown in FIG. 12, the side surface of the semiconductor bar 12, that is, the light emitting end surface of the finally obtained semiconductor light emitting device is covered and the entire surface is protected by an insulating protective film made of, for example, SiN. 15 is deposited by the CVD method. At this time, the protective film 15 is formed on the inner side surface of the separation groove 13, that is, the side surface 13 s having no light emitting end surface and the bottom surface.
Is formed.

Next, as shown in FIG. 13, the protective film 15 on the stripe-shaped mesa 14 is anisotropy exhibiting etching property in the direction orthogonal to the substrate surface, that is, in the thickness direction of the substrate 1 and the laminated semiconductor layer 8. Electrode layer 1 removed by etching
1 is exposed to the outside. In this way, each mesa 14, that is, each semiconductor light emitting device formed on each mesa, for example, a semiconductor laser, is subjected to characteristic measurement to inspect its quality.

Thereafter, the semiconductor bar 12 is divided for each mesa 14, that is, for each semiconductor light emitting device to obtain a semiconductor chip of each semiconductor light emitting device, which is shown in FIG. On the electrode layer 11 side, solder 17 is used to attach to a mounting portion 16 such as a header or a heat sink.

As described above, when manufacturing a semiconductor light emitting device such as a semiconductor laser, the quality of the characteristics of each semiconductor laser is inspected. However, this inspection is not performed in the state where each semiconductor laser is made into a chip. Since the handling thereof is extremely complicated, the semiconductor bar 12 in which a plurality of semiconductor lasers are arranged is usually used as described above.
It is performed in the state of.

On the other hand, in a semiconductor laser, in order to construct a Fabry-Perot resonator having excellent resonator characteristics required for laser oscillation, the resonator end face, that is, the laser light emitting end face is formed by a surface having excellent specularity. Need to be configured. Therefore, the cavity end face, that is, the light emitting end face is usually constituted by a cleaved surface of a crystal having excellent surface properties. That is, in the case of the above-described manufacturing method, when the semiconductor bar 12 is divided and obtained, the planes a ₁ , a ₂ ... In FIG. Therefore, in FIG.
0) When the surface is a crystal plane, the stripe direction, that is, the direction of the stripe-shaped current confinement groove 9 and the separation groove 13 is such that the above divided planes a ₁ , a ₂ ... Are the (001) planes.
As shown in FIG. 11, it is usually formed by photolithography so as to extend in the <0-11> axis direction, for example, H ₂ S.
When chemical etching is performed using an etchant formed by mixing O ₄ , H ₂ O ₂ and H ₂ O, the cross section of the separation groove 13 is
It becomes a so-called forward mesa shape in which the width decreases toward the bottom. When the separation groove 13 is formed as described above,
In the step of forming the insulating protective film 15 by the CVD method described in 1., the insulating protective film 15 is also formed in the separation groove 13, but the side surface of the separation groove 13 is an inclined surface that spreads above the separation groove 13. Therefore, the mesa 1 shown in FIG.
In the anisotropic etching for removing the insulating protective film 15 on the surface 4, the insulating protective film 15 on the side surface 13s of the separation groove 13 which spreads upward, that is, is inclined upward, is also removed by etching at the same time. The end surface of the active layer 4 is exposed to the outside on the side surface 13s.

Therefore, when the semiconductor light emitting device thus formed is soldered to the mounting portion 16 by the solder 17, as shown in FIG. 14, when the solder 17 rises along the side surface of the semiconductor chip, Active layer 4
When it comes close to or comes into contact with, the side surface 13s leaks, and the characteristics are deteriorated.

[0016]

SUMMARY OF THE INVENTION According to the present invention, in a semiconductor light emitting device, leakage does not occur even if solder creeps up during die bonding by soldering to the above-mentioned mounting portion without increasing the number of manufacturing steps. Provided are a semiconductor light emitting device and a method for manufacturing the same capable of effectively avoiding the occurrence of the above.

[0017]

In a semiconductor light emitting device according to the present invention, a laminated semiconductor layer having at least a first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer is formed on a semiconductor substrate. An insulating protective film is formed over the side surface of the laminated semiconductor layer having a light emitting end surface and the side surface having no light emitting end surface, and the side surface having no light emitting end surface faces the semiconductor substrate side. It is an inverted mesa-shaped inclined surface.

Further, according to the method of manufacturing a semiconductor light emitting device of the present invention, an epitaxial growth for epitaxially growing a laminated semiconductor layer having at least a first conductivity type cladding layer, an active layer and a second conductivity type cladding layer on a semiconductor substrate. Ohmic deposition of an electrode layer on the laminated semiconductor layer, and an inverted mesa separation in which the electrode layer and the laminated semiconductor layer are crossed in the thickness direction and the cross-sectional shape becomes wider toward the bottom. Reverse mesa groove forming step of forming grooves at predetermined intervals and forming stripe mesas between adjacent reverse mesa-shaped separation grooves, and dividing the stripe mesas into predetermined widths by dividing, for example, by cleavage. , A dividing step for obtaining a semiconductor bar in which a plurality of stripe mesas whose light emitting end faces are the divided sections are arranged in parallel, and the light emitting end faces of the semiconductor bar are formed. And a step of depositing an insulating protective film over the entire surface of the separation groove having the inverted mesa shape, and a step of removing the insulating protective film on the electrode layer by anisotropic etching. And a step of cutting the semiconductor bar at the separation groove to form a semiconductor chip having a semiconductor light emitting portion, thereby producing a target semiconductor light emitting device.

According to the above-described method of the present invention, the separation groove in the semiconductor bar has an inverted mesa shape, that is, the cross section of the separation groove has a stripe shape whose width increases toward the opening side. Is an inclined surface toward the bottom of the separation groove. Therefore, the insulating protective film deposited on the side surface of the separation groove is not removed by anisotropic etching for removing the insulating protective film on the electrode layer, and the side surface of the semiconductor chip to be finally formed. Remains in. Therefore, when this semiconductor chip is soldered to the mounting portion, leakage can be avoided even if the solder rises and the solder approaches or contacts the active layer.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a semiconductor light emitting device and a method for manufacturing the same according to the present invention will be described. In this example, it is applied to a double heterojunction type semiconductor laser made of an AlGaAs group III-V group compound semiconductor.

In this case, similarly to the above, as shown in a perspective view of a part thereof in FIG. 2, the first conductivity type is formed on the substrate 1, for example, the first conductivity type semiconductor substrate, for example, the n type GaAs substrate. , A buffer layer 2 made of n-type GaAs, a clad layer 3 made of, for example, n-type Al _x Ga ₁ -x As of the first conductivity type, an active layer 4 made of Al _y Ga _1-y As (x> y),
A clad layer 5 of a second conductivity type, for example, p-type Al _x Ga ₁ -x As, and a cap layer 6 of a second conductivity type, for example, p-type GaAs, are sequentially epitaxially grown to form a laminated semiconductor layer 8, and a cap layer 6 is formed thereon. A mask layer 7 for selective epitaxial growth such as a SiO ₂ layer is deposited.

As shown in a partial perspective view of FIG. 3, the mask layer 7 is subjected to pattern etching by, for example, photolithography to have a width corresponding to a resonator width to finally obtain the mask layer 7. The stripe patterns are arranged in parallel while maintaining a required distance, and a current confinement groove 9 having a depth reaching the cladding layer 5 is formed by etching across the cap layer 6 exposed to the outside except the stripe pattern. Then, a striped ridge is formed between each adjacent current constriction grooves 9.

In this case, the plane orientation of the semiconductor substrate 1 is {10
0} crystal plane, and the stripe direction is selected as the <011> axis direction as shown in FIG.

As shown in a partial perspective view in FIG. 4, the stripe-shaped mask layer 7 is not deposited and the semiconductor layer made of AlGaAs is exposed to the outside in the current confinement groove 9 of the first conductivity type, for example, n-type. Selective CVD of current confinement layer 9 of GaAs
It is formed by a method.

As shown in a partial perspective view in FIG. 5, the mask layer 7 is removed by etching back from the side where the mask layer 7 is formed, and the surface is flattened.

As shown in FIG. 6, one electrode layer 11 in ohmic contact is formed on the entire surface of the cap layer 7 by deposition. The electrode layer 1 is formed between the striped ridges 10 before or after the semiconductor bar 12 is formed.
1 and the laminated semiconductor layer 8 are formed into stripe-shaped separation grooves 13 for separating each semiconductor light-emitting device along the stripe direction of the ridge 10, that is, along the <011> axis direction. The depth of the separation groove 13 is the depth across the active layer 4,
For example, the stripe-shaped mesa 14 is formed by the separation groove 13 by being formed to a depth that traverses the laminated semiconductor layer 8. Although not shown, the separation groove 13 is formed by applying an etching resist, for example, a photoresist on the entire surface of the electrode layer 11, and by photolithography, along the <011> axis direction of the separation groove forming portion of the resist. A stripe-shaped opening is formed, through which, for example, H ₂ SO ₄ and H ₂
It is formed by chemical etching using an etchant of a mixed solution of O ₂ and H ₂ O. In this case, it is possible to form a so-called inverted mesa-shaped separation groove 13 whose cross section becomes wider toward the bottom by selecting an etching solution. That is, the separation groove 13 can be formed as a reverse taper inclined surface whose side surface 13s is inclined so as to face the substrate 1 side. Then, as indicated by chain lines a ₁ , a ₂ ... In FIG. 6, a width corresponding to a resonator length to be finally formed on the substrate 1 having the laminated semiconductor layer 8 across the stripe-shaped mesas 14. Then, as shown in FIG. 7, cleavage is performed to obtain a semiconductor bar 12 in which a plurality of desired semiconductor light emitting devices are arranged in parallel.

After that, as shown in FIG. 8 which is a sectional view of the main part thereof, the surface of the semiconductor bar 12 is covered with, for example, SiN.
The insulating protective film 15 is formed by the CVD method. As described above, when the CVD method is used, even if the inner side surface 13 s of the separation groove 13 is inclined in an inverse taper, the protective film 15 is well formed on the side surface 13 s and the bottom surface of the separation groove 13.

Next, as shown in the sectional view of FIG. 9, anisotropic etching showing a high etching property in the thickness direction of the substrate 1 and the laminated semiconductor layer is performed on the protective film 15 on the stripe-shaped mesa 14. Insulating protective film 15 on electrode layer 11
Is removed. When this anisotropic etching is performed, the insulating protective film 15 adhered and formed on the reverse tapered side surface 13s.
With regard to (2), it is surely left without being blocked by the mesa portion and being etched. That is, the end surface of the active layer 4 is not exposed to the outside even on the side surface 13s.

In this way, the characteristics of each semiconductor laser are measured through each mesa 14, that is, each semiconductor light emitting device formed on each mesa, for example, the electrode layer 11 separated with respect to the semiconductor laser, and the quality of each semiconductor laser is inspected.

After that, the semiconductor bar 12 is divided into each mesa 14, that is, each semiconductor light emitting device to obtain a semiconductor light emitting device according to the present invention whose schematic sectional view is shown in FIG. This semiconductor light emitting device, that is, a semiconductor chip,
As shown in FIG. 1, on the electrode layer 11 side, a header,
It is soldered to the mounting portion 16 such as a heat sink with the solder 17.

The semiconductor light emitting device according to the structure of the present invention is
Since the insulating protective film 15 is formed on the side surface 13s, even if the solder 17 crawls up, a leak occurs at the end face of the active layer, which causes deterioration of characteristics and generation of defective products. You can avoid that.

Further, according to the present invention described above, the side surface 13s
Despite the structure in which the insulating protective film 15 is attached to the above, the step of forming a protective film on the side surface 13s is not specially performed, and the insulating protection for the light emitting end face that should be originally formed is not performed. Since the film 15 is formed in the step of forming the film 15, the number of steps is not increased and therefore the manufacturing complexity is not brought about.

Further, according to the present invention, the light emitting end face, that is, the semiconductor bar 12 is divided by selecting the crystal direction of the stripe direction, that is, the crystal direction of the separation groove.
The cleavage surface of the crystal is formed as an excellent surface, and the separation groove 1
Since the side surface 13s of 3 can be formed as a reverse taper surface, that is, a reverse mesa groove, a semiconductor light emitting device having excellent characteristics can be configured.

The above example is based on the AlGaAs system III.
Although the semiconductor light emitting device made of a group V compound semiconductor has been described, the present invention can be applied to semiconductor light emitting devices made of AlGaInP and other various compound semiconductors. Further, in the above-mentioned example, the double heterojunction type is used. However, the structure is not limited to the above-described configuration, and a guide layer is provided between the active layer 4 and the first and second conductivity type cladding layers 3 and 5. SCH (Separate Confinemen)
The present invention can be applied to light emitting semiconductor devices including semiconductor lasers having various structures.

In the above example, the first conductivity type is n-type and the second conductivity type is p-type, but they may be opposite conductivity types.

[0036]

As described above, according to the structure of the present invention,
The active layer, that is, the side surface facing the end face of the light emitting operation portion is configured to be covered with an insulating protective film adhered to the light emitting end face, and according to the method of the present invention, without increasing the number of manufacturing steps. Since the above-mentioned insulating protective film can be formed, a semiconductor light emitting device having excellent characteristics and mass productivity can be configured.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of a semiconductor light emitting device according to the present invention.

FIG. 2 is a perspective view of a part of the manufacturing method of the present invention, which is a cross-sectional view of a part of the process.

FIG. 3 is a perspective view of a part of the manufacturing method of the present invention, which is a cross-sectional view of a part of the process.

FIG. 4 is a perspective view of a part of the manufacturing method of the present invention, which is a cross-sectional view in a step.

FIG. 5 is a partial perspective view showing a partial cross section in one step of an example of the manufacturing method of the present invention.

FIG. 6 is a partial perspective view in which a part is shown in a step in one step of the manufacturing method of the present invention.

FIG. 7 is a partial perspective view in which a part is shown in a cross-sectional view in one step of an example of the manufacturing method of the present invention.

FIG. 8 is a sectional view of a step of an example of the manufacturing method of the present invention.

FIG. 9 is a sectional view of a step of an example of the manufacturing method of the present invention.

FIG. 10 is a perspective view of a part of a step of a conventional manufacturing method, which is a cross-sectional view.

FIG. 11 is a partial perspective view showing a part of a step of a conventional manufacturing method in a sectional view.

FIG. 12 is a perspective view of a part of a step of a conventional manufacturing method with a cross-sectional view.

FIG. 13 is a partial perspective view showing a part of a step of a conventional manufacturing method in a sectional view.

FIG. 14 is a schematic cross-sectional view of a conventional semiconductor light emitting device.

[Explanation of symbols]

1 semiconductor substrate, 2 buffer layer, 3 first conductivity type clad layer, 4 active layer, 5 second conductivity type clad layer, 6
Cap layer, 7 mask layer, 8 laminated semiconductor layer, 9 current confinement groove, 10 ridge, 11 electrode layer, 12 semiconductor bar, 13 separation groove, 14 striped groove, 15 insulating protective film, 16 mounting portion, 17 solder

Claims (2)

[Claims] 1. A laminated semiconductor layer having at least a first conductivity type clad layer, an active layer, and a second conductivity type clad layer is formed on a semiconductor substrate, and a side surface having a light emitting end face of the laminated semiconductor layer. And an insulating protective film is formed over the side surface having no light emitting end surface, and the side surface having no light emitting end surface is an inverted mesa-shaped inclined surface that is inclined so as to face the semiconductor substrate side. A semiconductor light-emitting device characterized by the above. 2. An epitaxial growth step of epitaxially growing a laminated semiconductor layer having at least a first conductivity type clad layer, an active layer, and a second conductivity type clad layer on a semiconductor substrate, and an electrode layer on the laminated semiconductor layer. Ohmic-depositing step, and forming an inverted mesa-shaped separation groove that crosses the electrode layer and the laminated semiconductor layer in the thickness direction toward the bottom at a predetermined interval, and adjoins each other. An inverted mesa groove forming step of forming a stripe mesa between the inverted mesa-shaped separation grooves, and dividing the stripe mesa into a width having a predetermined length, and arranging a plurality of stripe mesas having the divided cross section as a light emitting end face in a parallel arrangement. A dividing step for obtaining a semiconductor bar, and a sectional surface of the semiconductor bar forming the light emitting end face;
A step of depositing an insulating protective film over the entire surface of the inverted mesa-shaped separation groove; a step of removing the insulating protective film on the electrode layer by anisotropic etching; And a step of cutting the bar in the separation groove to form a semiconductor chip having a semiconductor light emitting portion.