JPS5952552B2 - Manufacturing method of light emitting device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a light emitting device.

Conventionally, for example, in the manufacturing process of GaAsP light emitting devices,
After forming a P-N junction by diffusion, the surface is lightly etched to reduce the reduction in absorption of light emitted by a high concentration layer of diffusion, and after forming a front electrode, the back surface is polished and used as a pretreatment for forming a back electrode. Cover the surface with adhesive wax or a protective film.

The back surface was etched to improve the adhesion between the electrode and the back crystal. However, since the above method requires a step of covering the surface with adhesive wax or a protective film, it has the disadvantage that the surface is easily contaminated by them and that it takes a considerable amount of man-hours to apply and remove the adhesive. . SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a light emitting device that eliminates the above-mentioned drawbacks, prevents contamination of the device surface, and shortens the manufacturing process.

The method for manufacturing a light emitting device of the present invention includes a step of selectively diffusing impurities into the surface of a semiconductor substrate to form a PN junction, a step of forming an electrode on a part of the substrate surface in the diffused region, and This method is characterized by comprising the steps of polishing the back surface of the substrate, and etching and simultaneously removing the high concentration impurity layer on the surface of the diffused region and the layer destroyed by the polishing on the back surface of the substrate. According to the present invention, protection by adhesive or the like is not required during etching, so that the element surface is not contaminated.

Furthermore, the number of etching steps can be reduced by one step, and the steps of applying and removing adhesives are also unnecessary, so that the number of manufacturing steps can be significantly reduced. Hereinafter, the present invention will be described in detail based on examples and with reference to the drawings.

As shown in FIG. 1, after selectively diffusing P-type impurities onto the surface of an N-type GaAs wafer 1 using a silicon nitride film 2 as a mask to form a PN junction 3, the surface of the diffused region is An electrode 4 made of metal such as aluminum is formed at the center of the electrode.

The back side of the wafer is then polished to reduce the thickness of the wafer from 500μ to about 200μ.

Thereafter, by immersing it in a sulfuric acid-based etching solution for a certain period of time and etching it, the highly concentrated impurity layer 5 on the surface of the diffused region and the layer 6 destroyed by the polishing are removed at the same time. As a result, the high concentration impurity layer on the front surface is removed, and the light generated by the junction is no longer absorbed near the surface, improving the brightness of the light emitting device. On the other hand, the destructive layer on the back surface is removed. , it becomes easy to obtain an ohmic contact for the electrode formed on the back surface in the next step. The above etching process is performed, for example, as follows.

To process a large number of wafers in one etching process, place the semiconductor wafers against a wafer holder.
Separately, an etching solution is prepared, a semiconductor wafer is immersed in the etching solution under predetermined conditions, and the semiconductor wafer is transferred to clean water such as pure water to stop the etching.

In this example, as shown in FIG. 2, first, a pretreated GaAsP wafer 1 is placed against a Teflon wafer holder 7, and a glass etching container 8 is filled with sulfuric acid:hydrogen peroxide:pure water (=4 :1:1) etching solution 9
Prepare and control the temperature to 40°C using a heater, etc.

Next, hold the handle 10 of the wafer holder while the GaAsP wafer is standing upright, and gently shake it up and down for a predetermined period of time while gently immersing it in the etching solution. After that, immediately immerse it in pure water to stop the etching reaction. Approximately 1
After soaking in running pure water for about 0 minutes to replace the etching solution with water, proceed to the drying process. A centrifugal dehydration method was used as the drying method in this example. The wafer holder with the GaAsP wafer propped up is set in a predetermined position in a centrifugal dehydrator and dried for 30 seconds at a rotation speed of about 1000 rpm.
The etching process is completed by taking out the wafer holder 1 from the dehydrator and then taking out the GaAsP wafer from the wafer holder 1. With this method, it is possible to simultaneously satisfy different effects required for each of the front and back sides of the wafer without protecting either side of the wafer. Next, electrodes are formed on the back surface of the wafer and the wafer is separated into individual elements, followed by an assembly process to complete the light emitting element.

Although GaAsP wafers were used in the above embodiments, the present invention can of course be applied to materials such as GaAs, GaP, GaAlAs, etc. by changing the type of etching solution, etching conditions, etc.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a light emitting device for explaining the manufacturing method of the present invention, and FIGS. 2a and 2b are a front view and a side view, respectively, for explaining the etching method. 1...GaAsP wafer, 2...Silicon nitride film, 3...PN junction, 4...Electrode, 5...High concentration impurity layer, 6 ... Destruction layer by polishing, 7 ... Wafer holder 1
8...Etching container, 9...Etching liquid, 10...Wafer holder handle.

Claims (1)

[Claims] 1. PN by selectively diffusing impurities on the surface of the semiconductor substrate.
forming a bond on a part of the surface of the substrate in the diffused region; polishing the back surface of the substrate; and polishing the high concentration impurity layer on the surface of the diffused region and the back surface of the substrate. A method for manufacturing a light emitting device, comprising the step of etching and simultaneously removing the layer destroyed by the polishing.