JPS6094783A - Semiconductor light emitting device and manufacture thereof - Google Patents

Abstract

PURPOSE:To simplify the structure and to reduce the number of manufacturing steps by narrowing the widths of cap layers of lower side from the cap layer as compared with those of the cap layer, and electrically separating adjacent light emitting elements at the groove therebetween. CONSTITUTION:Light emitting element regions (a), (b), (c) are selectively etched through a V-groove 7 formed on a semiconductor light emitting body 11, and the first clad layer 2, an active layer 3 and the second clad layer 4 measured in the direction parallel to the surface of the substrate and vertical to the light emitting direction are narrowed in width than the cap layer 5. An etchant for etching only one of the two materials is used for the selective etching so that the layer 5 is not etched at the GaAs layer, but the second clad layer 4 is etched at the GaAlAs layer. Further, the layer 3 is of GaAs layer but has extremely reduced thickness, and it is etched together with the first layer 2 made of GaAlAs material, and the overhang 14 of the length (d) is projected at the upper side of the groove 13. Eventually, metal electrode layers 9a, 9b, 9c are adhered to the light emitting regions (a), (b), (c).

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a semiconductor light emitting device having a monolithic array structure and a method for manufacturing the same.

(Description of Prior Art) Semiconductor light emitting devices of various structures, such as semiconductor laser devices with a monolithic array structure and light emitting diodes, and methods of manufacturing them have been proposed. In this semiconductor light emitting device, the most important technique when forming a monolithic array of light emitting elements is a technique for electrically isolating adjacent elements. Regarding this point, for convenience of explanation of the present invention, first, this conventional device will be specifically explained.

FIG. 1 is a partial sectional view showing a semiconductor laser device with a monolithic array structure, which is a type of these conventional semiconductor light emitting devices. In FIG. 1, ■ is a semiconductor substrate, in this case, an n-GaAs substrate, and 2 is an n-GaAQA substrate.
s first cladding layer 31; l: n- or p-GaAQ
As active layer 4 is p-GaAQAs second cladding layer 5
is an n-GaAs camp layer, 6 is an electrode region Z
n diffusion region, 7 is a V-type isolation region (V groove),
8 is an insulating film; 9a, 9b, and 9c are metal electrode layers each in ohmic contact with the Zn diffusion region; and 10 is the other metal electrode layer provided on the lower surface of the substrate. In FIG. 1, the laser element region (
a), (b), and (C) are completely electrically isolated by V-grooves 7 that reach the active layer 3, respectively. However, since the depth of this V-groove 7 is usually about 5 gm to 10 km, in the manufacturing process of semiconductor devices, it is difficult to form such a deep V-groove on the wafer surface and perform subsequent processing, as described below. As is clear from the above, this is not desirable, and therefore, this V-groove causes difficulty in the manufacturing process.

2(A) to 2(D) are manufacturing process diagrams of the semiconductor laser device having the conventional structure shown in FIG. 1, in order to explain this problem more specifically. Conventionally, as shown in Fig. 2 (A
), a first cladding layer 2, an active layer 3, a second cladding layer 4 forming a double heterojunction, and a cap layer 5 are formed on a semiconductor substrate 1 by epitaxial growth. A plurality of Zn diffusion regions 6 reaching at least the second cladding layer 4 from the upper surface are formed in a direction perpendicular to the illustrated cross section to provide a planar drive electrode region, thereby forming a semiconductor light emitting body (also known as a wafer). ) forming +1.

Next, as shown in FIG. 2(B), a V-groove 7 is dug in this light emitting body 11. The V-groove 7 is formed, for example, by chemical etching between the Zn diffusion regions 6, which are electrode regions, in a direction parallel to the Zn diffusion regions 6, so that the electrode regions 6 are electrically squared.

Subsequently, as shown in FIG. 2(C), an insulating film 8 such as 5i02 is deposited on the surface of the light emitting body 11 (epitaxial layer surface) including the side surfaces of the V-groove 7, and then,
Only the portion of the insulating film 8 existing on the -1- side of the electrode region 6 is removed to form the window 12.

Next, as shown in FIG. 2(D), striped metal electrode layers 9a, 9b, and 9c are provided on the striped electrode region 6 through this window 12.

However, when forming the window 12 mentioned above,
・The insulating film 8 is removed using lithography technology, but as shown in Figure 2 (C), the resist is applied to the wafer surface with uneven surfaces such as the It is very difficult to apply. Therefore, it is preferable to avoid the process shown in FIG. 2(C).

Also, when forming the metal electrode layers 9a, 9b, and 9c, the semiconductor laser child regions (a) and (b) adjacent to each other are
) and (C) using photolithography technology, which poses the same difficult problems as mentioned above.

As described above, according to the conventional manufacturing method of semiconductor light emitting devices, since photolithography technology is applied to the surface of a wafer having an uneven surface, manufacturing is complicated and the number of manufacturing steps is large, resulting in a decrease in manufacturing yield. However, it has the disadvantage of being expensive to manufacture.

(Objective of the Invention) The present invention has been accomplished in order to eliminate the drawbacks of the above-described conventional device and its manufacturing method regarding a method for separating each semiconductor light emitting element in a semiconductor light emitting device having a monolithic array structure.

Therefore, the first object of the present invention is to provide a semiconductor light-emitting device with a monolithic array structure in which electrical separation is N1 between adjacent light-emitting elements without using a dividing means that combines a trench and an oxide film. 17. It is in the i offer.

Another object of the present invention is that without the need for photorin technology,
An object of the present invention is to provide a method for manufacturing a semiconductor light emitting device having a monolithic array structure in which adjacent light emitting elements can be electrically placed between each other.

(Structure of the Invention) In order to achieve this object, according to the semiconductor light emitting device of the present invention, the first A structure in which the widths of the cladding layer, the active layer, and the second cladding layer are narrower than the width of the cap layer measured in the same direction, and a metal electrode layer is directly deposited on the upper surface of the cap layer. It is characterized by 17 things.

Furthermore, according to the method for manufacturing a semiconductor light emitting device of the present invention,
A first cladding layer, an active layer, a second cladding layer, a cap layer, and an electrode region are formed on a semiconductor substrate, and a semiconductor light emitting body is formed through grooves provided to separate each light emitting element region. Selective etching is performed on each of these light emitting device regions, and the widths of the first cladding layer, active layer, and second cladding layer measured in a direction perpendicular to the light emission direction and parallel to the semiconductor substrate surface are determined by the cap layer. The metal electrode layer is formed narrower than the width of the semiconductor light emitting body, and then a metal electrode layer is formed on the semiconductor light emitting body.

(Explanation of Examples) Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 3(A) to 3([1)] are manufacturing process diagrams showing a method of manufacturing a laser device which is an embodiment of the semiconductor light emitting device of the present invention. Note that this figure is an enlarged sectional view showing the state of the apparatus at each manufacturing stage, taken in an open plane, and is schematically shown within the scope of understanding the present invention. Components similar to those shown in FIGS. 1 and 2 are designated by the same numbers. In addition, in the figure, hatching and the like representing a cross section are partially omitted to avoid complication of the drawing.

First, as shown in FIG. 3(A), a first cladding layer of n-GaAQAs is formed on the surface of an n-GaAs semiconductor substrate 1, an active layer 3 of n- or p-GaAs, and a first cladding layer of n-GaAQAs is formed on the surface of an n-GaAs semiconductor substrate 1.
s second cladding layer and n-GaAs cap layer 5,
For example, by epitaxial growth, Z1 expansion/+([region 6
A semiconductor light emitting body 11 in which a plurality of are formed is prepared. Next, as shown in FIG. 3(B), a plurality of V grooves 7 are dug between each of these electrode regions 6 of the semiconductor light emitting body 11, reaching at least the first cladding layer 2 from the upper surface of the cap layer 5. light emitting device regions (a), (b), (
c) form. For the formation of this V-groove, for example, it is necessary to use Elachan I as an etchant, which has the property that the etching rate does not change depending on the material such as GaAs or GaAQAq, and the etching rate varies markedly depending on the crystal plane orientation. Specifically, %S
o 4 : I(z O□:1lzO=l:1:1 etchant is used, (100) GaAs surface or (
+00) A straight V groove parallel to the (110) direction of the GaAOAs surface can be easily formed.

Next, as shown in FIG. 3(C), the semiconductor light emitting body 11
Each of these light emitting element regions (a
), (b), and (c) were selectively etched to form the first cladding layer 2 and the active layer measured in a direction perpendicular to the light emission direction (perpendicular to the plane of the figure) and parallel to the substrate surface. The widths of the layer 3 and the second cladding layer 4 are formed to be narrower than the width of the cap layer 5 measured in the same direction. This selective etching means etching only one of the two materials, in this case Ga agent As and G
Etching only the GaAOAs layer of aAs
An etchant to be described later that does not etch the s-layer is used. When such an etchant flows into the V-groove 7, the cap layer 5 is not etched because it is a GaAs layer, but the second cladding layer 4 is etched because it is a GaAQAs layer, and this etching also spreads to the underside of the cap layer 5. It is done in a roundabout manner. Furthermore, although the active layer 3 is a GaAs layer, it is extremely thin compared to other epitaxial layers, so it is etched together with the first cladding layer 2, which is made of GaAQAs material barbs, underneath it. ) is shown in the figure. You can. Since the cap layer 5 remains without being etched, the 411' feature of this groove structure is formed by the eaves or eaves 14 of length d.
is located at a point projecting into the upper part of the groove 13.

Next, a metal for an electrode is uniformly deposited over the entire surface of the wafer, that is, the semiconductor light emitting body 11 in which the grooves 13 have been formed in this manner. Therefore, as shown in FIG. 3(D), each cap layer 5'' in each light emitting element region (a), (b), (c) is directly connected to a metal electrode layer! 3a,
13b and 9c, a metal layer is deposited on the semiconductor substrate l within the groove 13 between these light emitting element regions.
The latter metal layer does not have any adverse effect on the operation of the light emitting device. Furthermore, a metal electrode layer IO is provided on the lower surface of the semiconductor substrate.

According to the structure of the semiconductor laser device of the present invention obtained in this way, the electrode metal layers 9a, 9b, and 9c are not limited to the Zn diffusion region 6, which is the electrode region, but also to the upper surface of the cap layer 5. These semiconductor laser element regions (a) are in direct contact without an oxide film and are adjacent to each other.
, (b), (C) as well as electrode metal layers 9a, 9b,
9c are also reliably electrically separated from each other by grooves 13 that are wider than the gaps between the eaves 14 of adjacent cap layers 5. On the other hand, in the conventional semiconductor laser device shown in FIG. It is only in electrical contact with 6.

However, the difference between the two is that in this structure, the region where the bias current substantially flows is the region shown in the figure corresponding to the Zn diffusion region 6, so the magnitude of the threshold current for laser oscillation is There is no problem since almost the same value is obtained for both.

By the way, the etchant used for selective etching is G.
An important factor is that the etching speeds of aAs and GaAQAs are different.
2) There is an etchant developed by researchers at Oki Electric Industry KK published on pages 9 to 17. This etchant is N
This is an etching solution based on H,0H-H,O
The GaAs (+00) plane and GaAQAs (
100) Etching rate for the surface γ-11□o2/
Nl+40H is shown in FIG. In the figure, the horizontal axis plots the mixing volume ratio γ representing the composition of the etching solution, and the vertical axis plots the etching rate l/ff1 in. And curve I is Gao4AQ, )+
Δg (100) and π indicate etching on the GaAs (100) plane. From this figure, γ=H,O2/N
By appropriately changing the values of ll and Oll, GaA
It is clear that QAs can be selectively etched.

(Effects of the Invention) As is clear from the above, according to the semiconductor light-emitting device of the present invention, each layer of the semiconductor substrate below the cap layer, irrespective of the combination of grooves and insulating films. The width of the cap layer is narrower than the width of the cap layer, and the electrical isolation between adjacent light emitting element regions is achieved by a groove between them, resulting in a simpler structure and fewer manufacturing steps than before. Therefore, the manufacturing yield of the device is improved. Furthermore, according to the manufacturing method of the present invention, selective etching is performed through the groove provided in the trench and reaching the first cladding layer from the ``-'' side surface of the cap layer.
A portion of each layer on the substrate is etched to make it narrower than the cap layer, and then an electrode metal layer is directly deposited on the cap layer, so each light emitting element region can be electrically isolated reliably. In addition, it can be manufactured more easily and with fewer steps than in the past without using photolithography technology, which has the advantage of improving the manufacturing yield and lowering the manufacturing cost.

Because of these advantages, the present invention is suitable for application to a semiconductor light emitting device having a monolithic array structure.

It is clear that the present invention is not limited only to the embodiments described above. That is, although GaAQAs laser was explained as a semiconductor laser, InGaAsP
It may also be a laser. Furthermore, the conductivity type can also be the opposite conductivity type to that described above. Furthermore, the light emitting diode is not limited to the laser. Furthermore, for example, a three-dimensional structure can be created by providing an insulator in the electrical isolation grooves and on the metal electrode layer of the obtained one-dimensional array of semiconductor light-emitting devices and growing new crystals on the two sides of the insulator. (You can also go.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining an example of a conventional semiconductor light emitting device, FIGS. 2(A) to (D) are manufacturing process diagrams for explaining a conventional method for manufacturing a semiconductor light emitting device, and FIG. (A) to (D) are manufacturing process diagrams for explaining the semiconductor light emitting device of the present invention and its manufacturing method, and FIG. FIG. l...Semiconductor substrate, 2...First cladding layer 3...
Active layer 4... Second cladding layer 5... Cap layer 6... Electrode region (or diffusion region) 7... V-type isolation region (lit) 8...
Insulating films 9a, 9b, 8c, 10-=metal electrode layer 11...semiconductor light emitting body, 12...(insulating film) window 13...groove,
14... (cap layer) eaves (a), (b)
, (c)...Light emitting element region. 11- He-mouth \11 \, l ^heQ Loichi

Claims (1)

[Claims] 1. A plurality of light-emitting device regions formed by laminating a first cladding layer, an active layer, a second cladding layer, and a cap layer in sequence from the substrate surface side on the substrate surface of a semiconductor substrate. With,
In a semiconductor light emitting device having a monolithic array structure having an electrode region extending from the upper surface of the cap layer to the second cladding layer in each of these light emitting element regions, the electrode region is perpendicular to the light emitting direction and located on the surface of the substrate. The width of the first cladding layer, the active layer, and the second cladding layer measured in a direction parallel to the cap layer is narrower than the width of the cap layer measured in the same direction, and metal is directly applied onto the upper surface of the cap layer. A semiconductor light emitting device characterized in that it has a structure in which an electrode layer is deposited. 2. A first cladding layer on the substrate surface of the semiconductor substrate. Prepare a semiconductor light emitting body in which an active layer, a second cladding layer, and a cap layer are sequentially laminated, and a plurality of electrode regions are formed that reach the second cladding layer from the -1- side surface of the cap layer. Next, trenches are dug between the electrode regions of the semiconductor light emitting body, reaching at least the first cladding layer from the upper surface of the cap layer, and a plurality of light emitting element regions are formed, and then the semiconductor light emitting device is assembled. During manufacturing, selective etching is performed on each of these light emitting device regions through the grooves to form the first cladding layer, active layer, and The method is characterized by comprising the steps of: forming the second cladding layer to be narrower than the width of the cap layer measured in the same direction; and then depositing a metal electrode layer on the semiconductor light emitting body. A method for manufacturing a semiconductor light emitting device.