JPS59112666A - Manufacture of light emitting element - Google Patents

Abstract

PURPOSE:To decrease the forward voltage and to improve the light emitting efficiency of a light emitting element by attaching an anode electrode after etching the surface of a reverse conductive type epitaxial layer on a semiconductor substrate, and attaching a cathode electrode to the back surface of the substrate. CONSTITUTION:The surface of a P type epitaxial layer 12 on an N type semiconductor substrate 11 is treated with an etchant to form ultrafine uneven surface. Then, a diffused layer 15 of high density is formed to compensate the decrease in the density of the layer 12 due to etching, thereby preventing the increase in the forward voltage drop of a light emitting element. Then, a thin metal film is covered, patterned to form an anode electrode 13, a cathode electrode 14 is provided on the back surface of the substrate, thereby obtaining a light emitting element group. It is diced along a broken line to divide into pellets. According to this structure, since etched before the electrodes are formed, no increase in the forward voltage based on the reduction in the area of the electrodes due to side etching exists, the margin rate of the area of the electrodes can be reduced to decrease the size of the element, light emitting efficiency is high and the forward voltage is low.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a light emitting element that has high luminous efficiency and can be operated with a low pressure and one source.

[Technical Background of the Invention and Point of View] In general, devices that control channel switching signals using infrared light emitting signals, such as those used in remote control devices for EVA TV, operate at low tortoise pressures such as those in dry water ponds. There is a demand for a light-emitting element that is capable of emitting light and has high luminous efficiency. Conventionally, such light emitting elements are shown in Figures 1(,) to (c).
) is formed by the process shown in That is, as shown in the figure (a), a P-type epitaxial layer 12 is formed on an N-type semiconductor substrate 11, and a metal thin film such as aluminum is deposited on this epitaxial layer 12 and patterned to form an anode electrode 13. , l 3°... and depositing a metal thin film on the other surface (back surface) of the substrate 1 to form a cathode polarization 14 to form a light emitting element group as shown in the figure (b). obtain. Next, a phosphoric acid-based etching solution is applied to the anode electrodes 13, 13, . After etching the exposed surface 12' of the epitaxial layer 12 on which... is formed, etching is performed along the broken line in FIG.
Divide into each pellet as shown.

Note that in order to increase the luminous efficiency by setting the impurity concentrations of the N-type substrate 1 and the P-type epitaxial layer 12 to the same level, a layer may be added between the N-type substrate 11 and the P-type epitaxial layer 12 as necessary. An N-type epitaxial layer is formed.

However, in the light-emitting element formed in the above process, in the etching process of the light-emitting surface (the protrusion iz2' of the P-type epitaxial layer 12), the side of the anode electrode 13 is etched as shown as A and A in FIG. Etching liquid also enters the side, causing side etching. This dump, anode electrode 1
3 and the epitaxial layer 12 (ψ1], for example, GaAs).Since the contact area is small, the forward voltage vF of the element is high, so a high power supply voltage is required.

In order to prevent an increase in the forward voltage vF due to such a reduction in contact area, it is possible to form a large anode electrode in advance with side etching in mind. If you try to increase the amount, there is a drawback that the number of chips that can be obtained from one wafer decreases.

In order to prevent side etching, it has been considered to cover the anode electrode 13 and the contact point between this electrode 13 and the epitaxial layer 12 with a protective film made of a material that will not be etched before etching. Not only does this require a coating step, but it is also difficult to peel off this protective film.

[Purpose of the invention]

This invention was made in view of the above circumstances,
The objective is to provide a method for manufacturing a light emitting element that has high luminous efficiency and low head pressure, and can also reduce costs by downsizing the element.

[Summary of the invention]

That is, in this invention, a conductive layer is formed on a semiconductor substrate.
After forming a slope-shaped epitaxial layer and etching the surface of this epitaxial layer, an anode is formed on the etched surface, and a cathode electrode is also formed on the other side (back surface) of the semiconductor substrate.

[The Fruit of Invention 2 If! Example i] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIGS. 3(a) to 3(d) show the manufacturing process. First, as shown in FIG. 3(a), a P-type epitaxial layer 12 is formed on an N-type semiconductor substrate 1.
The surface of the epitaxial layer 12 is etched using a phosphorus-fM2-based etching solution to form fine irregularities on the surface of the epitaxial layer 120 as shown in (b) lxl. Next, as shown in the figure (C), zinc Zn or the like is diffused onto the epitaxial layer 12 to form a high concentration layer 15:f:. This is because when etching is performed in the wafer state, the 51Mt of the P-type epitaxial layer 12 decreases, and when an anodic acid layer 12 is formed in the next step, the contact resistance increases and the forward voltage of the light emitting element increases. It is. Then, as shown in the figure (d), a metal thin film is deposited and patterned on the high concentration layer 15 formed on the evitagital layer 1112 to form good anodic acids i 13 , 13 , . . . on the substrate 1. The cathode electrode 14 is formed by depositing a metal thin film on the surface (back surface) of the curved blade to improve the light emitting element snoring. Next, dice the pellets along the broken lines in Figure Q (d) above to separate them into individual pellets.

Note that, as described above, before forming the P-type epitaxial layer 12 on the N-type semiconductor substrate 1),
A type epitaxial layer may be formed, and a P type epitaxial layer 12 may be laminated on this N type epitaxial layer.

According to the process described above, since the surface of the epitaxial layer 12 is etched in advance before forming the electrodes, the forward voltage (2) of the light emitting element does not decrease due to side etching, and the area of the electrodes is adjusted to accommodate the side etching. Since there is no need to design a large wafer, the number of elements obtained from one sheet of Ueno can be increased and costs can be reduced. Moreover, as the manufacturing process becomes more complex.

According to this invention, in the conventional method, when trying to improve the luminous efficiency by about 1.5 times compared to the one without etching, the forward voltage (1) becomes higher, whereas the forward voltage (1) increases by 1.8 times.
It was possible to improve the voltage by about 2 times, and the forward voltage vF of the element was at the same level as the conventional level.

〔Effect of the invention〕

As described above, according to the present invention, a method for manufacturing a light emitting element can be obtained that has high luminous efficiency and low forward voltage, and can also reduce costs by downsizing the element.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the conventional manufacturing method of a light emitting element, Figure 2 is a diagram for explaining a side etching nog, and Figure 3 is a diagram for explaining a side etch nog.
The figure is a diagram for explaining a method of manufacturing a light emitting device according to one embodiment of the present invention. 11... Semiconductor substrate, 12... Epitaxial layer,
13... Anode electrode, 14... Cathode electrode. Applicant's agent Patent attorney Takeshi Suzue Hikoga 1 picture 3 pictures

Claims (1)

[Claims] A step of forming an epitaxial layer of opposite conductivity type on the surface of the semiconductor substrate, a step of etching the front surface of the epitaxial layer to form unevenness, and a step of forming an uneven layer on the etched epitaxial layer and the back surface of the semiconductor substrate, respectively. 1. A method for manufacturing a light-emitting element, which comprises the steps of forming a poem.