JP3505913B2 - Method for manufacturing semiconductor light emitting device - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] [Technical Field of the Invention The present invention relates to a <br/> method for manufacturing the semiconductor light emitting equipment. 2. Description of the Related Art A semiconductor light emitting device, for example, 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 thereon. Normally, both end faces of a Fabry-Perot resonator for causing laser oscillation of this semiconductor laser, that is, side faces on which light emitting end faces are formed, have required optical characteristics and are protected by, for example, SiN to protect them. A protective coating is applied. In other aspects, the above-mentioned insulating protective film is simultaneously deposited, but is eventually removed during the manufacturing process of 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 less. Since the thickness is about tens of μm, the die bonding performed by soldering this semiconductor laser to a header or a heat sink by soldering in consideration of the heat radiation effect from the laser oscillation part is performed on the electrode layer side on the above-described laminated semiconductor layer. Made in. However, in this case, since the position of the active layer is close to the die bond portion, the solder crawls along the side surface of the semiconductor laser to easily reach the active layer, causing a leak to occur and deteriorating characteristics. Or the occurrence of defective products. 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 buffer layer 2 made of n-type GaAs is formed on a substrate 1 such as an n-type GaAs substrate.
Layer 3 of Al _x Ga _1-x As type, 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 cladding layer 5 of a _{1 -X} As and a cap layer 6 of p-type GaAs, and a mask layer 7 for selective epitaxial growth, for example, an SiO ₂ layer is deposited thereon. As shown in FIG. 3, the mask layer 7 is subjected to pattern etching by, for example, photolithography,
This mask layer 7 has a width corresponding to the finally obtained resonator width, is formed in a stripe pattern arranged in parallel while maintaining a required interval, and further, the cap layer 6 exposed to the outside other than the stripe pattern A current constriction groove 9 is formed by etching, for example, to a depth reaching the cladding layer 5 across the substrate, and a stripe-shaped ridge 10 is formed between each adjacent current confinement groove 9. [0007] As shown in FIG. 4, the current confining groove 9 which is not covered by the stripe-shaped mask layer 7 and is exposed to the outside.
Inside, a current confinement layer 9 of n-type GaAs is formed by a selective CVD (Chemical Vapor Deposition) method. As shown in FIG. 5, the mask layer 7 is removed by etching back the entire surface from the side where the mask layer 7 is formed, and the surface is flattened. As shown in FIG. 10, one electrode layer 11 which is in ohmic contact with the entire surface of the cap layer 6 is formed on the cap layer 6, and the electrode layer 1 is interposed between the stripe-shaped ridges 10.
1 and a stacked semiconductor layer 8 are separated for each semiconductor light emitting device to form a separation groove 13 to form a stripe-shaped mesa 14. Then, as shown by chain lines a ₁ , a _2, ... In FIG. 10, the substrate 1 having the laminated semiconductor layer 8 is placed on a plane crossing the stripe-shaped mesa 14 so as to have a width corresponding to the resonator length to be finally formed. Then, as shown in FIG. 11, a plurality of target semiconductor light emitting devices are arranged in parallel to obtain a semiconductor bar 12. [0010] Thereafter, as shown in FIG. An insulating protective film 15 made of, for example, SiN for protecting the light emitting end face is formed on the entire surface covering the light emitting end face of the semiconductor light emitting device obtained by the CVD method. Formation of the coercive Mamorumaku 15 is made and the time the inner surface or no side 13s and the bottom surface of the light emitting end surface of the separation groove 13. Next, as shown in FIG. 13, the protective film 15 on the stripe-shaped mesa 14 is anisotropically showing an etching property in a direction perpendicular to the substrate surface, that is, in the thickness direction of the substrate 1 and the laminated semiconductor layer 8. The electrode layer 1 is removed by etching.
1 is exposed to the outside. In this way, the quality of each mesa 14, that is, each semiconductor light emitting device formed on each mesa, for example, a semiconductor laser is measured, and the quality of each is inspected. 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 the semiconductor light emitting device, which is shown in a schematic sectional view in FIG. Then, on the side of the electrode layer 11, the solder 17 is soldered to a mounting portion 16 such as a header or a heat sink. As described above, when a semiconductor light emitting device, for example, a semiconductor laser is manufactured, each semiconductor laser is inspected for its quality. However, this inspection cannot be performed in a state where each semiconductor laser is chipped. Since the handling becomes 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 form a Fabry-Perot resonator having excellent resonator characteristics required for laser oscillation, the end face of the resonator, that is, the emission end face of the laser beam, is required to have a mirror surface. It is necessary to configure. Therefore, usually, the cavity end face, that is, the light emission end face is constituted by a cleavage plane of a crystal having excellent surface properties. That is, in the case of the above-described manufacturing method, when the semiconductor bar 12 is obtained by being divided, the planes a ₁ , a _2, ... In FIG. Therefore, in FIG.
0) When the crystal plane is used, the direction of the stripe, that is, the direction of the stripe-shaped current confinement groove 9 and the separation groove 13 is set so that the above-mentioned divided planes a ₁ , a ₂ .
As shown in FIG. 11, for example, H ₂ S is formed by photolithography so as to extend in the <0-11> axis direction.
When chemically etched using an etchant formed by mixing O ₄ , H ₂ O ₂ and H ₂ O, the cross section of the separation groove 13 becomes
It becomes a so-called forward mesa shape in which the width decreases toward the bottom. When such a separation groove 13 is formed, FIG.
In the step of forming the insulating protective film 15 by the CVD method described in the above section, 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 extending 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 upper surface 4, the insulating protective film 15 on the side surface 13 s of the separation groove 13 extending upward, that is, inclined upward, is also etched and removed at the same time. The end face 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 with the solder 17 as shown in FIG. 14, when the solder 17 rises along the side surface of the semiconductor chip, Active layer 4
, A leak is generated at the side surface 13s, and the characteristics are degraded. According to the present invention, in a semiconductor light emitting device, solder creeps up in the above-described die bonding by soldering to a mounting portion without increasing the number of manufacturing steps. the semiconductor light emitting equipment which was also to be able to effectively avoid the occurrence of leak
And a method for producing the same. [0017] According to an aspect of the present onset Akira, on a semiconductor substrate, at least a first conductivity type cladding layer, an active layer, the laminated semiconductor layer is formed having a second conductivity type cladding layer An insulating protective film is formed over the side surface of the laminated semiconductor layer having the light emitting end surface and the side surface having no light emitting end surface, and the side surfaces having no light emitting end surface face toward the semiconductor substrate. Semiconductor light emitting device with inverted mesa-shaped inclined surface
To manufacture . That is, the method of manufacturing a semiconductor light emitting device of the present invention is directed to an epitaxial growth method for epitaxially growing a laminated semiconductor layer having at least a first conductive type clad layer, an active layer, and a second conductive type clad layer on a semiconductor substrate. A step of forming an electrode layer on the laminated semiconductor layer in an ohmic manner, and an inverse mesa-shaped separation in which the cross-sectional shape becomes wider toward the bottom across the electrode layer and the laminated semiconductor layer in the thickness direction. A groove is formed at a predetermined interval, and a reverse mesa groove forming step of forming a stripe mesa between adjacent reverse mesa-shaped separation grooves and a width of the stripe mesa having a predetermined length are cut, for example, by cleavage. A dividing step of obtaining a semiconductor bar in which a plurality of stripe mesas having the divided section as a light emitting end face are arranged in parallel, and setting the light emitting end face of the semiconductor bar to The step of depositing and forming an insulating protective film over the entire surface of the divided cross section and the reverse mesa-shaped separation groove; and removing the insulating protective film on the electrode layer by anisotropic etching. A target semiconductor light emitting device is manufactured through a step and a step of forming a semiconductor chip having a semiconductor light emitting portion by cutting the semiconductor bar in the separation groove. According to the above-described method of the present invention, the separation groove in the semiconductor bar is formed in an inverted mesa shape, that is, the separation groove is formed in a stripe shape in which the cross section becomes wider toward the opening side. Is an inclined surface toward the bottom of the separation groove. Therefore, the insulating protective film formed 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 finally formed semiconductor chip is not removed. To remain. Therefore, when the 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. An embodiment of a semiconductor light emitting device according to the present invention and a method of manufacturing the same will be described. In this example,
This is a case where the present invention is applied to a double heterojunction type semiconductor laser using an AlGaAs III-V compound semiconductor. In this case, as described above, as shown in a perspective view of a part of FIG. 2, a substrate 1, for example, a semiconductor substrate of the first conductivity type, for example, an n-type GaAs substrate, is provided with the first conductivity type. for example the buffer layer 2 by n-type GaAs, Al, for example, n-type first conductivity type _X Ga _1-X As cladding layer 3 _{by, Al y Ga 1-y As} (x> y) active layer 4 by,
A stacked semiconductor layer 8 is formed by sequentially epitaxially growing a cladding 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. A mask layer 7 for selective epitaxial growth, for example, an SiO ₂ layer is deposited. As shown in a partial perspective view in FIG. 3, the mask layer 7 is subjected to pattern etching by, for example, photolithography, and has a width corresponding to the resonator width in which the mask layer 7 is finally obtained. It was formed in a stripe pattern in parallel arranged in a spaced relationship by a required distance, further by etching the current blocking layer 9 G of this stripe across the cap layer 6 which is exposed to the outside other than the pattern leading to for example the cladding layer 5 depth Formed, each adjacent current constriction groove 9
A stripe ridge is formed between G. In this case, the plane orientation of the semiconductor substrate 1 is ｛10
A crystal plane is defined as 0 °, and the stripe direction is selected in the <011> axis direction as shown in FIG. As shown in a partial perspective view in FIG. 4, a first conductivity type, eg, n-type, is formed in a current confinement groove 9 G in which a stripe-shaped mask layer 7 is not covered and a semiconductor layer made of AlGaAs is exposed to the outside. GaAs current confinement layer 9 is selectively C
It is formed by VD. As shown in a partial perspective view of 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 which is in ohmic contact with the cap layer 7 is entirely formed. Before or after the formation of the semiconductor bar 12, the electrode layer 1 is interposed between the stripe-shaped ridges 10.
1 and the stacked semiconductor layer 8 are formed along the stripe direction of the ridge 10, that is, along the <011> axis direction. The depth of the separation groove 13 is a depth crossing the active layer 4,
For example, a stripe-shaped mesa 14 is formed at a depth crossing the stacked semiconductor layer 8 by the separation groove 13. Although not shown, an etching resist such as a photoresist is applied to the entire surface of the electrode layer 11 and the separation groove 13 is formed along the <011> axis direction on the separation groove forming portion of the resist by photolithography. A stripe-shaped opening is formed, and through this opening, 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, a so-called inverted mesa-shaped separation groove 13 whose cross section becomes wider toward the bottom can be formed by selecting an etching solution. That is, the separation groove 13 can be formed as a reverse-tapered inclined surface that is inclined such that the side surface 13s faces the substrate 1 side. Then, as shown by chain lines a ₁ , a _2, ... In FIG. 6, the substrate 1 having the laminated semiconductor layer 8 is placed on a plane crossing the stripe-shaped mesas 14 with a width corresponding to the finally formed resonator length. Next, as shown in FIG. 7, cleavage is performed to obtain a semiconductor bar 12 in which a plurality of target semiconductor light emitting devices are arranged in parallel. Thereafter, as shown in FIG. 8 which is a cross-sectional view of the main part, the surface of the semiconductor bar 12 is covered with, for example, SiN.
Is formed by the CVD method. As described above, when the CVD method is used, even if the inner side surface 13s of the separation groove 13 is inclined in a reverse taper, the protection film 15 can be formed well on the side surface 13s and the bottom surface of the separation groove 13. Next, as shown in the sectional view of FIG. 9, the protective film 15 on the stripe-shaped mesas 14 is subjected to anisotropic etching exhibiting high etching properties in the thickness direction of the substrate 1 and the laminated semiconductor layer. Go to the insulating protective film 15 on the electrode layer 11
Is removed. When this anisotropic etching is performed, the insulating protective film 15 formed on the side surface 13s of the reverse taper is formed.
Is reliably left without being blocked by the mesa portion and etched. That is, the end face of the active layer 4 is not exposed to the outside also on the side surface 13s. 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. Thereafter, the semiconductor bar 12 is divided for each mesa 14, that is, for 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 a mounting part 16 such as a heat sink by solder 17. In the semiconductor light emitting device obtained by the manufacturing method of the present invention, the insulating protective film 15 is formed on the side surface 13 s. It is possible to avoid the occurrence of a leak and deterioration of characteristics and occurrence of a defective product. According to the present invention described above, the side surface 13s
Despite the configuration in which the insulating protective film 15 is applied to the side surface, a process of forming a special protective film on the side surface 13s is not adopted, and the insulating protection for the light emitting end face that should be originally formed is not performed. Since it is formed in the step of forming the film 15, the number of steps is not increased, and thus the production is not complicated. Further, according to the present invention, by selecting the crystal direction of the stripe direction, that is, by selecting the crystal direction of the separation groove, the light emitting end face, that is, the division of the semiconductor bar 12 can be divided.
It is formed as an excellent surface in the cleavage plane of the crystal.
The third side surface 13s can be formed as a reverse tapered surface, that is, a reverse mesa groove, so that a semiconductor light emitting device having good characteristics can be configured. The above-mentioned example is based on the AlGaAs II
Although a semiconductor light emitting device using an IV group compound semiconductor has been described, the present invention can be applied to a semiconductor light emitting device using an AlGaInP-based compound semiconductor and various other compound semiconductors. In the above-described example, the double hetero junction type is used. However, the present invention is not limited to the above-described configuration, and a guide layer is provided between the active layer 4 and the first and second conductive type cladding layers 3 and 5. Interposed SCH (Separate
Confinement Heterostructure
The present invention can be applied to semiconductor light emitting devices including re) type semiconductor lasers and semiconductor lasers having various configurations. In the above-described example, the first conductivity type is n-type and the second conductivity type is p-type. However, these may be of the opposite conductivity type. [0036] [Effect of the Invention] As described above, according to this onset bright, active layer, i.e. the side end face of the light-emitting operation unit faces, a structure covered by an insulating protective film deposited on the light emitting end face According to the method of the present invention, it is possible to form the above-mentioned insulating protective film without increasing the number of manufacturing steps, so that it is possible to manufacture a semiconductor light emitting device having excellent characteristics and mass productivity. Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view of an example of a semiconductor light emitting device obtained by a manufacturing method of the present invention. FIG. 2 is a partial perspective view in which a part in one step of an example of the manufacturing method of the present invention is a cross-sectional view. FIG. 3 is a partial perspective view in which a part in one step of an example of the manufacturing method of the present invention is a cross-sectional view. FIG. 4 is a partial perspective view in which a part of one step of an example of the manufacturing method of the present invention is a cross-sectional view. FIG. 5 is a partial perspective view in which a part in one step of an example of the production method of the present invention is a cross-sectional view. FIG. 6 is a partial perspective view in which a part in one step of an example of the manufacturing method of the present invention is a cross-sectional view. FIG. 7 is a partial perspective view in which a part in one step of an example of the manufacturing method of the present invention is a cross-sectional view. FIG. 8 is a sectional view of one step of an example of the manufacturing method of the present invention. FIG. 9 is a sectional view of one step of an example of the manufacturing method of the present invention. FIG. 10 is a partial perspective view in which a part of one step of a conventional manufacturing method is a cross-sectional view. FIG. 11 is a partial perspective view in which a part of one step of a conventional manufacturing method is a cross-sectional view. FIG. 12 is a partial perspective view in which a part in one step of a conventional manufacturing method is a cross-sectional view. FIG. 13 is a partial perspective view in which a part in one step of a conventional manufacturing method is a cross-sectional view. FIG. 14 is a schematic sectional view of a conventional semiconductor light emitting device. [Description of Signs] 1 semiconductor substrate, 2 buffer layer, 3rd conductive type clad layer, 4 active layer, 5 second conductive type clad layer, 6
Cap layer, 7 mask layer, 8 laminated semiconductor layer, 9 electrodes
Flow constriction layer, 9 G current confinement groove, 10 ridge, 11 electrode layer, 12 semiconductor bar, 13 separation groove, 13 s side
Surface, 14 stripe-shaped grooves, 15 insulating protective film, 16
Mounting part, 17 solder

Claims (1)

(57) Claims 1. 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. Forming an electrode layer on the laminated semiconductor layer in an ohmic manner, and forming an inverted mesa-shaped separation groove having a cross-section that becomes wider toward the bottom across the electrode layer and the laminated semiconductor layer in the thickness direction. An inverse mesa groove forming step of forming a stripe mesa between adjacent inverse mesa-shaped separation grooves formed at a predetermined interval, and dividing the stripe mesa into a width having a predetermined length, and dividing the divided section into a light emitting end face. A dividing step of obtaining a semiconductor bar in which a plurality of stripe mesas are arranged in parallel; and a dividing section of the semiconductor bar, the light emitting end face being formed.
A step of depositing and forming an insulating protective film over the entire surface of the reverse mesa-shaped separation groove; a step of removing the insulating protective film on the electrode layer by anisotropic etching; Forming a semiconductor chip having a semiconductor light emitting portion by cutting the bar at the separation groove.