JPS60253285A - Manufacture of semiconductor surface light-emitting element - Google Patents

Abstract

PURPOSE:To manufacture a semiconductor surface light-emitting element having a high output and long life easily without using diffusion and a boring process by forming high reflection multilayer films on the substrate side of a light-emitting element and shaping an internal current constriction layer onto the multilayer films on liquid-phase epitaxial growth. CONSTITUTION:First and second reflecting layers 2a, 2b are laminated alternately onto the substrate surface 1a of a P-GaAs substrate 1 to form high reflection multilayer films 2, and a P type GaAs layer 3 is grown on the multilayer films 2. One part of the P-GaAs layer 3 is etched to shape a columnar projecting section 3b. An N-AlzGa1-zAs layer is grown onto an exposed surface 2c and the projecting section 3b as a current constriction layer 4 while the surface 4a thereof is flattened. The layer 4 is melted back up to approximately the same position as the interface between the multilayer films 2 and the constriction layer 4 to shape a hole 5. A P-AlyGa1-yAs layer is grown onto the substrate with the current constriction layer 4 with the hole as a first clad layer 6. An active layer 7 is formed as an AlxGa1-xAs layer, and a second clad layer 8 consisting of an N-AlyGa1-yAs layer and a contact layer 9 composed of an N-GaAs layer are grown onto the layer 7 in succession, thus obtaining double hetero-structure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a semiconductor surface emitting device for optical communication or information processing.

(Prior Art) Conventionally, AQGaAs semiconductor surface emitting devices having a burr structure are known (for example, C, A, Burrus).
etal rApplied Physics Lett
er J (1870) WOl, 1? , P97). FIG. 3 is a cross-sectional view showing an example of this surface emitting device, and the manufacturing method for this device is to use liquid phase epitaxial growth of 711Q to Ga7-yA on an n-type GaAs substrate 21.
N-type tube consisting of s layer - cladding layer 22゜AQ xGa
P-type active layer 23 consisting of t-yAs layer, AQyGaz-
After sequentially forming a P-type cylindrical rad layer 24 made of a yAs layer and an n-type current confinement layer 25 made of a GaAs layer, a layer is formed from the surface of the current confinement layer 25 through this layer 25 in order to form a current injection region. Circular p+ reaching the n-type cladding layer 24
In order to form the diffusion region 26 and further take out the light,
A circular light extraction hole 27 is dug in the part of the substrate 21 located directly under this p+ diffusion region 26 until it reaches the n-type cladding layer 22, and then the p-side electrode 28 and the n-side electrode 28 are
was forming.

(Problems to be Solved by the Invention) However, in this conventional manufacturing method, as shown in the figure, after liquid phase epitaxial growth and before electrode formation,
Diffusion process for current concentration and light extraction hole 2
7 formation steps are required, and these steps contribute to the deterioration of the characteristics of the device.

Furthermore, it is difficult to align the light extraction hole 27 and the p'' diffusion region 26, and the depth of diffusion determines the characteristics of the element, so it is necessary to precisely control this depth. The manufacturing process was complicated and difficult for several reasons.

Furthermore, since the active layer 23 is mounted using a fusing material such as solder, this reduces the reliability of the device and contributes to shortening the life of the device.

Furthermore, in this conventional structure, the light traveling from the active layer toward the side opposite to the substrate is absorbed by the current confinement layer 25, so that this light cannot be used effectively at all.

The purpose of this invention is to simply and easily produce semiconductor surface emitting devices with high reliability, high output, and long life without using the diffusion process and drilling process that are carried out in the conventional manufacturing process of semiconductor surface emitting devices. An object of the present invention is to provide a method for manufacturing a semiconductor surface emitting device.

(Means for Solving the Problems) In order to achieve this object, the main point of the present invention is to provide a semiconductor surface emitting device with a structure in which light is extracted from the growth crystal surface side opposite to the substrate, and Instead of forming a high-reflection multilayer film on the substrate side of the element and then forming a current confinement region by diffusion on this high-reflection multilayer film, an internal current confinement layer is created during liquid phase epitaxial growth. .

Therefore, according to the method for manufacturing a semiconductor surface emitting device of the present invention, a first cladding layer, an active layer, a second cladding layer constituting a double heterostructure, and a current confinement layer are formed on a semiconductor surface. In manufacturing a light emitting device, a highly reflective multilayer film is formed on a substrate made of GaAs, a GaAs layer is grown on this highly reflective multilayer film, and then this GaAs layer is etched to form cylindrical convex portions. is formed, and then, in -times of liquid phase epitaxial growth steps, sequentially,
An Al) zGa tyAs layer as a current confinement layer is grown by liquid phase epitaxial growth on the above-mentioned high-reflection multilayer film so as to embed the convex portion, and the composition dependence of the meltback rate during liquid phase epitaxial growth is utilized. Then, a circular hole is formed in the current confinement layer, and the MyGa layer as the first cladding layer is formed on the substrate having the current confinement layer with the hole.
l-yAs layer, NJxGat-tAs layer as the active layer, and AQyGaz-yAs layer as the second cladding layer (
The composition ratio is in the relationship of x<y, x<z) and is characterized by liquid phase epitaxial growth.

(Function) According to such a method, GaAs on the high reflection multilayer film
After the formation of the circular convex portion of the layer, each layer of the device up to just before electrode formation can be successively formed in the second liquid phase epitaxial growth process, which eliminates the diffusion process and the formation of light extraction holes. A semiconductor surface emitting device can be manufactured simply and easily without any process, and
Since the characteristics of the manufactured device are not thermally or mechanically damaged, there is no risk of deterioration of the characteristics.

Furthermore, the structure of the obtained device is such that light is extracted from the crystal growth surface side opposite to the substrate, and the substrate side is mounted, so the active layer is not affected by the flux and is highly reliable. It is possible to improve performance and longevity.

Furthermore, since a highly reflective multilayer film is provided on the substrate side with respect to the active layer, light, which has not been used effectively in the past, can be reflected by this multilayer film and used effectively, so that high output can be obtained.

(Example) Hereinafter, an example of the method for manufacturing a semiconductor surface emitting device according to the present invention will be described with reference to FIGS. 1(A) to (H) and FIG. 2.

First, FIG. 1(A) will be explained. A high-reflection multilayer film 2 consisting of alternating layers of first reflective layers 2a and second reflective layers 2b is formed on a substrate surface la of a substrate l made of p-GaAs. This first reflective film 2afep -AQ uGa t-
uAs layer, and the second reflective film 2b is p-AQ vGa
t-vA1z layer (u>v, composition ratio of the active layer described later
For X<U.

For example, organometallic pyrolysis method (Koc
vn method). The thicknesses of these six films 2a and 2b are set so that the optical path length of the emitted light is 1/4 wavelength. If the composition ratios of these reflective films 2a and 2b are u = 0.7 and v = 0.2, the entire high reflective multilayer film 2 has 60 layers, and the reflectance is 85% (Akira Ibaraki, stone material Shin, Ken Iga: 11382 Proceedings of the 43rd Autumn Academic Conference of the Japan Society of Applied Physics, 130). On this high-reflection multilayer film 2, a p-type GaAs film made of the same material as the substrate is coated.
Grow layer 3. This p-GaAs layer 3 is completely removed during meltback described later. In this way, a structure as shown in FIG. 1(A) is obtained.

Next, as shown in FIG. 1B, a portion of the p-GaAs layer 3 is etched from its surface 3a using photolithography to form a cylindrical convex portion 3b. The exposed surface of the high-reflection multilayer film 2 exposed by this etching is designated as 20.

Subsequently, the member on which the convex portion 3b is formed is placed in an epitaxial growth furnace. In this case, a sliding type epitaxial growth furnace is used. Next, as shown in FIG. 1(C), in this growth furnace, the exposed surface 2c and the convex portion 3b are completely buried so that the surface 4a becomes flat. AQ zGa tzAs layer as current confinement layer 4
It is grown by liquid phase epitaxial growth.

Next, slide it in the growth furnace and prepare the G for meltback.
Transfer to aAs solution. Therefore, when meltback is performed using unsaturated melt, as shown in FIG. 1(D), the protrusions 3
The meltback progresses until the surface 3a of b appears.

Since the meltback speed of AQGaAs is much slower than that of GaAs, the meltback of the convex portion 3b of GaAs proceeds quickly. As this selective meltback of the convex portion 3b progresses, the state shown in FIG. When it melts back to the same or almost the same position as (corresponding to the position of the exposed surface 1c), this meltback is stopped and the hole 5 is formed. During this meltback, the side wall 4b of the circular hole 5 in the current confinement layer 4 melts back more on the surface side and less on the substrate side when viewed from the surface side of this layer 4 toward the substrate 1. It has a slope where the diameter becomes larger on the surface side. This meltback forms internal current confinement layer 4 having circular holes 5.

After completion of this meltback, each layer of a double heterostructure as shown in FIG. 1(G) is grown by liquid phase epitaxial growth. For this purpose, the substrate (hereinafter collectively referred to as a wafer) having the holed current confinement layer 4 is slid and transported to the next liquid phase epitaxial growth solution, where p -AQ vG
The first cladding layer 6 is grown by growing the a7-yAs layer. In this case, by controlling the melt supersaturation degree and the growth time of this epitaxial growth, the first cladding layer 6 in the hole 5 portion maintains a concave shape.

Next, slide this wafer in the same way to obtain p −AQ
xGa t-xAs layer (in this case, x<y, x<z
, x<U , so that it becomes a lens shape. By repeating sliding and growing in the same way, n AQy is formed on this active layer 7.
Ga no! Second cladding layer 8 made of As layer and n-G
A wafer having a double heterostructure as shown in FIG. 1(G) is obtained by sequentially growing contact layers 9 made of aAs layers by liquid phase epitaxial growth.

Thereafter, as shown in FIG. 1H, etching is performed from the surface 9a of the contact layer 9 using a photolithography technique to form a columnar light extraction window (or hole) 10. .

According to the manufacturing method of the present invention described in -, after forming the high reflection multilayer film 2 and the GaAs layer 3 on the substrate and forming the convex portions 3b of GaAs, this member was once placed in an epitaxial growth furnace. After that, without putting anything in or out, that is, -
In the second liquid phase epitaxial growth process, a wafer having a structure immediately before electrode formation is obtained, in which an internal current confinement layer and each layer forming a double heterostructure are grown on the substrate.

FIG. 2 shows the n-side electrode 1 on the wafer formed in this way.
1 and the p-side electrode 12 are vapor-deposited to form a surface emitting device, which is shown in a cross-sectional view.

In a surface emitting device having such a structure, a current injected from the p-side electrode 12 as an ohmic electrode passes from the substrate l through the multilayer film 2 and through the center of the hole 5, and then flows from the first cladding layer 6 to the active layer 7 to It flows from the second cladding layer 8 to the contact layer 9 to the n-side electrode 11 as an ohmic electrode. However, the current confinement layer 4 is n-type and the first cladding layer 6 is p-type.
Since there is a reverse bias between the substrate 1 and the n-type current confinement layer 4, no injection current flows from the substrate 1 to the first cladding layer 6 through this n-type current confinement layer 4, and therefore, this n-type current confinement layer functions effectively. However, the first cladding layer 6 and active layer 7 in the central portion of the hole 5 serve as current paths, and current concentration occurs only in that portion.

Therefore, in the case of this surface emitting device, this current confinement layer 4
Since the layer composition ratio is x<y, the light obtained by recombining and emitting light in the region of the active layer 7 directly above the hole 5 is transmitted from the active layer 7 to the second cladding on the side opposite to the substrate 1. The light can be extracted from the light extraction window 10 of the contact layer 9 through the path of the layer 8.

In addition, since the high-reflection multilayer M2 has low light absorption and is an ideal high-reflection mirror, it can reflect most of the light emitted from the active layer 7 toward the substrate, so that most of the emitted light This light can be effectively output from the light extraction hole 10.

Furthermore, since the side wall 4b of the hole 5 in the current confinement layer 4 is inclined, a portion of the light traveling in the direction of the active layer 7 → first cladding layer 6 → current confinement layer 4 is reflected by the inclined surface of the side wall 4b. (because X < Z), it can be extracted as output light, resulting in high output.

Furthermore, the current concentrating effect of the internal current confinement layer 4 and this layer 4
The composition ratio of N in the active layer 7 is larger than the composition ratio of the active layer 7 (X
<Z), there is no possibility of optical switching operation due to absorption of light, and high output can be easily obtained through high current operation.

In addition, since the active layer 7 is lens-shaped, it has a high light collecting ability, and therefore the single emission diameter becomes small, which is advantageous for coupling with an optical fiber.

The invention is not limited to the embodiments described above. For example, the conductivity types of each layer can be made to be opposite conductivity types by using only one substrate. That is, the combination of a p-type substrate and an n-type current confinement layer may be replaced by a combination of an n-type substrate and a p-type current confinement layer.

The conditions for etching and liquid phase epitaxial growth described above can be appropriately set according to the design.

Further, the dimensions, shapes, arrangement relationships, etc. of each part can be appropriately set.

(Effects of the Invention) As is clear from the above explanation, according to the method for manufacturing a semiconductor surface emitting device of the present invention, the G of the high reflective multilayer film is reduced.
After the cylindrical convex portion of the aAs layer is formed, an internal current confinement layer is built up by successive liquid phase epitaxial growth times by utilizing the dependence of the meltback rate on the composition ratio during liquid phase epitaxial growth. , the device of the present invention does not require a diffusion process like the conventional one, and has a structure in which light is extracted from the surface opposite to the substrate, so there is no need for a process to make holes in the substrate. teeth,
It has the advantage of being simple and easy to manufacture.

Furthermore, since a highly reflective multilayer film is provided on the substrate side of the active layer, light that was previously not used effectively can be reflected by this multilayer film and used effectively, making it possible to obtain higher output than before. I can do it.

Furthermore, since the fluxing agent such as the solder material is placed on the substrate side, it has the advantage of high reliability and long life.

Furthermore, since an internal current confinement layer is formed in this method, the element structure is such that current concentration can be performed efficiently, and therefore high current operation is possible.

Further, according to the method of the present invention, since the active layer can be grown in a lens shape, the coupling between the surface emitting device and the optical fiber can be improved.

The semiconductor surface emitting device according to the present invention is suitable for application to the fields of optical information processing and optical communication where long life is required.

[Brief explanation of the drawing]

FIGS. 1A to 1H are manufacturing process diagrams for explaining an embodiment of the method for manufacturing a semiconductor surface emitting device of the present invention. FIG. 2 is a schematic cross-sectional view showing the structure of a semiconductor surface-emitting device manufactured by the method of the present invention. FIG. 3 is a schematic cross-sectional view for explaining a conventional method for manufacturing a semiconductor surface-emitting device. 1...Substrate (or GaAs substrate) la...Substrate surface, 2...Highly reflective multilayer film 2a-"first reflective film (or AQ uGa r-uAs layer) 2 b-
・Second reflective film (or AQvGal-yAs layer) 2C・
...Exposed surface 3 (of the high-reflection multilayer film)...-GaAs layer, 3a=...Surface 3b (of the GaAs layer)...Convex portion 4 (cylindrical of GaAs)...Current confinement layer (or AQ zGa t-zAs layer) 4a...
Surface 4b (of the current confinement layer)... Side wall 5 (of the hole)... Hole 6 (of the current confinement layer)... First cladding layer (or AQyGa or As layer) 7... Active layer (or AQ xGa )-yAs layer)
8... Second cladding layer (or AQ yGa 7- y
As layer) 9... contact layer (or GaAs layer) 8a
... (contact layer) surface 10 ... light extraction window, 11.12 ... electrode L.
··light. To patent applicant Oki Electric Industry Co., Ltd. 1%j. Do\Heku Roichino\NoQguchi-Isata Shiba Power Theory Procedural Amendment August 19, 1985 Director General of the Patent Office Tono Uga Michibe 1 Indication of Case 1989 Patent Application No. 1013253 2 Name of Invention Relationship with the Case of Person Who Amends Manufacturing Method for Semiconductor Surface Emitting Devices 3 Patent Applicant Address (〒-105) 1-7-12 Toranomon, Minato-ku, Tokyo Name (028) Oki Electric Industry Co., Ltd. Representative Nankai Hashimoto 4 Agent Address: 170 tt (988) 55E13
1-20-5 Ikebukuro White House Building, Toshima-ku, Tokyo Detailed explanation column of the invention in the specification, brief (1) of the drawing,
Specification, page 2, line 18 rPhysic Letter
Correct J to rPhysics Letters j. (2), same, page 9, line 14, ``Correct the exposed surface 1cJ of the substrate 1 to be the exposed surface 2cJ of the high-reflection multilayer film 2.'' (3), same, page 13, line 10, rx<z ``y''
By correcting ≠2 to 1, the 11th line "High output can be obtained" can be increased by 1. ” he corrected. (4), page 15, lines 2 and 3, ``There is an advantage.'' There is one advantage. Correct it with J. (5), same, page 16, line 3 “Manufacturing to explain” Tue r
It has been corrected to ``Manufacture 1 for explanation'', and the line 6, ``Route sectional view'' has been corrected to ``R Schematic sectional view'', 1. (8) Correct as shown in the correction diagram attached with Figure 2 of 3 drawings.

Claims (1)

[Claims] (2) In manufacturing a semiconductor surface emitting device by forming a first cladding layer, an active layer, a second cladding layer, and a current confinement layer constituting a double heterostructure on a substrate, A high reflection multilayer film is formed on a GaAs substrate, and a GaAs layer is grown on the high reflection multilayer film. Next, the GaAs layer is etched to form a cylindrical convex portion, and then, in the second liquid phase epitaxial growth step, the convex portion is successively buried on the high reflection multilayer film. An AQ zGa /-2AS layer as a current confinement layer is grown by liquid phase epitaxial growth so as to fill the current confinement layer, and a circular hole is formed in the current confinement layer by utilizing the composition dependence of the meltback rate during liquid phase epitaxial growth. On the substrate having the holed current confinement layer, an AQyGaz-yAs layer as the first cladding layer, an AOxGa/-yAs layer as the active layer, and a TenoAQ yGaz-yAs layer as the second cladding layer (the composition ratio is x<y, x
A method for manufacturing a semiconductor surface emitting device, characterized by performing liquid phase epitaxial growth. 2. The high reflection multilayer film is an AQ uGa/-uAs film and an AQ vGa/-vAs film (composition ratio is v<u,
x<u, x<v), and the film thickness of these six films is such that the optical path length of the emitted light is 1/
2. The method of manufacturing a semiconductor surface emitting device according to claim 1, wherein the wavelength is set to four.