JPH01228181A - Semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To improve an element of this design in a yield and a light takeout efficiency by a method wherein a spherical lens, whose top position in a direction perpendicular to a semiconductor substrate is made flush with an electrode plane or positioned downward toward an active layer side, is formed on a light takeout face of the semiconductor substrate. CONSTITUTION:An n-electrode 19 is formed on a substrate 11 except a light takeout window by a lift-off method, and a dielectric film 20 of SiO2, TiO2, or the like is also formed thereon except the window. Next, a resist 21 is made to cover the light takeout section making it spherical and the dielectric film 20, which is heated till the resist is fluid. And, when an etching is performed until the resist 21 is completely removed, a spherical lens whose top is lower than the n-electrode can be obtained. By these processes, not only the formation of electrodes and the bonding can be improved in an operating efficiency to improve a yield but also a light takeout efficiency can be improved by shortening the distance between a light emitting section 7 and the lens as an element retains a mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a monosilicon lens type light emitting diode for optical communication.

(Prior Art) Surface-emitting diodes for optical communication have the characteristics of lower cost and higher multiplication characteristics than semiconductor lasers, and are used as light sources for near- and medium-range optical communication. Light from light emitting diodes is emitted almost isotropically.

Various coupling methods have been devised to efficiently guide this spread light into the thin core of an optical fiber. For example, as shown in Fig. 3, there is a method of increasing the coupling efficiency by bonding a glass bulb lens (3) to the light emitting surface of a surface emitting diode with resin (4), and a method of increasing the coupling efficiency by bonding a glass bulb lens (3) to the light emitting surface of a surface emitting diode with resin (4); )
As shown in Figure 2, a spherical processed surface (6) is created on a semiconductor substrate (1) using a method such as ion etching to form a monocylindrical lens, and the tip of the optical fiber is melted to form a spherical fiber (5). There are ways to do this.

The spherical processed surface has, for example, a circular shape with a diameter of approximately 90 mm, and the apex is approximately 7 microns higher than the substrate.

(Problems to be Solved by the Invention) However, in conventional monolithic lens type light emitting diodes, the apex of the lens is higher than the electric bridge surface, which makes it difficult to form electrodes after lens processing, and also makes it difficult to form electrodes on the lens part during bonding. There was a risk of damaging the surface. Furthermore, since the lens apex is above the electrode surface,! ! It is necessary to strengthen the physical strength. Therefore, if the substrate is made thicker, the distance between the light emitting section (7) and the lens surface becomes longer, which poses a problem in that the light extraction efficiency is structurally restricted.

[Means to solve the problem]

The present invention has been made in view of the above points.
The purpose of this is to improve the shape of the lens side of monosilicon lens type light emitting diodes, increase the work efficiency of electrode formation and bonding, improve the yield of device manufacturing, and maintain the mechanical strength of the device. Mama,
By providing a semiconductor light-emitting element in which the distance between the light-emitting part and the lens is shortened to improve light extraction efficiency, the gist of the device is that one surface of the semiconductor substrate is formed with an electrode thereon and becomes a light-extraction surface, and the semiconductor In a surface-emitting light emitting diode on which the other surface of the substrate has an active layer, a spherical lens shape is formed on the light extraction surface, and the position of the apex of the lens in the direction perpendicular to the semiconductor substrate is on the light extraction surface. This is a semiconductor light emitting device characterized by being located at the same position as the formed electrode or closer to the active layer side.

[Function] Since the electrode surface of the light extraction surface is located above the spherical lens surface, electrode formation and bonding operations are easily performed. Furthermore, since the spherical lens surface is located inside the semiconductor substrate and closer to the light emitting section where the active layer is located than the electrode surface, light extraction efficiency is improved.

〔Example〕

The present invention will be described below based on embodiments shown in the open view.

FIGS. 1(a) and 1Cb) are cross-sectional views of essential parts of an embodiment according to the present invention, in which an n-1nP cladding layer Q7J is formed on an n-1nP substrate (11), a p-1nGaAs P active layer side,
After a p-InP cladding layer 04) and a P''-1nGaAsP cap layer 0ω are epitaxially grown in sequence, a SiO□ film 06) is formed for current confinement, and a window for current injection is formed by photolithography.

Next, a p-electrode 0η is formed on the entire surface, and A u -P H308) is laminated for bonding.

Figure 2 is an explanatory diagram of the process of forming a spherical lens.
As shown in Figure (a), on the light extraction surface side, an n-electrode θ9) is formed on the n-1nP substrate θ1) by a lift-off method except for a window portion for light extraction. Next, a dielectric film r20 such as 5ift or TiO 230°
The resist is heated to a temperature higher than C to form a sagging shape as shown in Fig. 2b).Next, etching is performed by ion beam etching until the resist disappears, as shown in Fig. 2(C). ) as shown in n-1nPjJ plate 01)
Above, we obtain a spherical lens shape whose apex is no higher than the n-electrode 09). A spherical lens has a circular shape with a diameter of approximately 120 mm.
The height of the apex is approximately 161M, and the apex is approximately 30 m above the substrate surface.
-It's getting lower. Finally, the dielectric film QI is removed.

[Effects of the Invention] As explained above, according to the present invention, the position of the apex in the vertical direction of the semiconductor substrate in the shape of a spherical lens formed on the light extraction surface of the semiconductor substrate is the same as the electrode surface, or is more active than the electrode surface. Because it is located on the layer side, it does not damage the lens surface in the next process, making handling easier and improving yield.
Even if the substrate is made thick enough to maintain the mechanical strength of the element, the distance between the light emitting part and the lens can be kept close, which has the excellent effect of increasing light extraction efficiency.

[Brief explanation of the drawing]

1(a) and 1(b) are sectional views of essential parts of an embodiment according to the present invention, FIGS. 2(a) to 4(C) are explanatory diagrams of the manufacturing process of the embodiment, Figures (a) and (g) are sectional views of main parts of a conventional example. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... Electrode, 3... Glass bulb lens, 4... Resin, 5... Spherical fiber, 6... Spherical processed surface, 7... Light emitting part, 8...
・Epitaxial layer, 1l-n-1nP substrate, 12
-n-1nP ground layer, 13-p-1nGa
AsP active layer, 14...p-1nP cladding layer,
15...P21nGaAs P+tube layer, 16
- SiOz film, 17...p electrode, 18-Au
-PH3,19・n-electrode, 20... dielectric film,
21...Resist.

Claims (2)

[Claims] (1) One surface of the semiconductor substrate has an electrode formed thereon and serves as a light extraction surface, and the other surface of the semiconductor substrate has a spherical lens shape on the light extraction surface in a semiconductor light emitting device having an active layer thereon. 1. A semiconductor light emitting device, wherein a vertex of the lens in a direction perpendicular to a semiconductor substrate is located at the same position as an electrode formed on a light extraction surface or closer to an active layer side. (2) The semiconductor light emitting device according to claim 1, wherein the semiconductor substrate is made of InP.