JPS6155780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an electrode of a semiconductor device, and particularly to a method of forming an electrode containing gold as a main component in a - group compound semiconductor device.

In this field, metal electrodes formed on the surface of - group compound semiconductor substrates are generally made of metal electrodes such as AuBe,
It is constructed using a gold alloy layer such as AuSi.

Incidentally, heat treatment is sometimes performed to further enhance the ohmic properties, but in this case, on the other hand, the bonding strength between the gold alloy layer and the bonding wire is reduced.

In addition, in an attempt to improve this bonding strength, a gold layer of the same quality as the bonding wire is sometimes further laminated on the alloy layer, and the bonding wire is bonded to this gold layer, but the bonding strength is still not sufficiently improved. do not have.

Under the circumstances described above, the present inventor investigated the cause of such problems and found that although the ohmic properties between the gold alloy layer and the semiconductor substrate were improved in the above heat treatment, the constituent components of the semiconductor substrate, Or, in the former case, bonding properties at the interface between the wire and the gold alloy layer are inhibited due to the ohmic components of the gold alloy layer diffusing to the surface of the electrode film and forming a thin oxide layer on the surface layer. It was found that in the latter case, bonding properties at the interface between the gold layer and the gold alloy layer were inhibited.

An object of the present invention is to improve the ohmic properties due to heat treatment, and also to improve the bonding properties by avoiding the inhibition of bonding properties caused by this heat treatment.

The present invention provides a step of forming an ohmic electrode in ohmic contact with the substrate by depositing a gold alloy layer on a - group compound semiconductor single crystal substrate and performing heat treatment, and a step of forming an ohmic electrode in ohmic contact with the substrate, and removing the ohmic electrode produced during the heat treatment. A method for forming an electrode for a semiconductor device, which comprises a step of etching away the exposed surface layer of the electrode, and a step of forming a bonding electrode by laminating and depositing a gold layer on the ohmic electrode. and bonding properties can be improved.

An embodiment of the present invention will be described below with reference to the drawings.

In manufacturing an example of a GaP light emitting diode, as shown in FIG. 1, a GaP substrate 1 has an N-type region 1n exposed on one main surface and a P-type region 1p on the other main surface, and a PN junction 1pn is formed in the substrate. and its P
An AuBe alloy layer and an AuSi alloy layer 2 as ohmic electrodes are vacuum-deposited on each exposed surface of the type crystal and the N-type crystal. Next, heat treatment was performed at 520°C for 5 minutes in _N2 gas to obtain ohmic contact between the ohmic electrode and the exposed surface of the substrate. In order to remove the Be and Ga oxide layers 3, this GaP substrate is heated to boiling level in hydrochloric acid for 10 minutes, then thoroughly washed with pure water and dried (Figure 3). Next, an Au layer 4 is vacuum deposited on the P-type ohmic electrode and formed into a predetermined electrode pattern using photolithography (FIG. 4).

According to the method of the present invention described above, it is possible to improve the ohmic properties between the surface layer of the ohmic electrode and the substrate, and the oxide layer formed on the surface layer of the ohmic electrode is removed to form a bonding electrode. The electrode and the bonding electrode are formed with high adhesiveness.

This significantly improves bonding efficiency and yield, for example when using a fully automatic bonder.
In the past, the yield not only varied widely, such as 95-99%, but also had a low average yield, but with the present invention, a yield of 99.99% is always ensured, improving product manufacturing efficiency. This showed a remarkable improvement in yield.

It goes without saying that the etchant for the ohmic electrode in the present invention is not limited to hydrochloric acid, but may also be other mineral acids, surfactants, etc.

[Brief explanation of the drawing]

FIGS. 1 to 4 are cross-sectional views of a part of a GaP light emitting diode, showing a part of the manufacturing process of the device. 1 ...GaP substrate, 1p...P region of GaP substrate,
2'... Ohmic electrode, 3... Oxide layer on the surface of the Ohmic electrode, 4... Bonding electrode.

Claims (1)

[Claims] A step of forming an ohmic electrode in ohmic contact with the substrate by depositing a gold alloy layer on a 1- group compound semiconductor single crystal substrate and performing heat treatment, and an exposed surface layer of the ohmic electrode that occurs during the heat treatment. 1. A method for forming an electrode for a semiconductor device, comprising the steps of etching away the oxide layer of the oxide layer, and then forming a bonding electrode by laminating the ohmic electrode with a gold layer.