JPS5932068B2 - Group 3-5 compound semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ■-V group compound semiconductor device, and specifically relates to a semiconductor device having a stable electrode with low contact resistance with a semiconductor chip.

■-Semiconductor devices using V group compound semiconductors, such as Ga
In manufacturing a P-light emitting diode, it goes without saying that the crystal itself must have excellent characteristics, but the quality of the contact resistance of the electrode material used there, as well as the reliability of the device, etc. This is an element that has a large impact on quality. In other words, variation in electrode contact resistance has a large effect on variation in diode drive voltage, and for diodes with large electrode contact resistance, the Joule heat generated by the resistance increases the temperature of the element, which causes light emission. This will cause a decrease in efficiency and shortened service life. Therefore, it is desirable for the electrode material to be one that can stably obtain a sufficiently low contact resistance and that has as little variation in contact resistance as possible during mass production. By the way, GaP(
7) For n-type crystals, alloys of Au and Si or Au have been used as electrode materials that can almost satisfy these conditions.
An alloy of Ge and Ge is used. However, for example, for a low-concentration n-type crystal with a carrier concentration of 1 to 2 x 1017 (V7!-3), these alloys of Au and Si or alloys of Au and Ge have sufficiently low contact resistance.
It has been difficult to obtain uniform electrodes. Therefore, the present invention provides an n-type electrode material that has sufficiently low contact resistance and less variation even for such n-type GaP crystals with low carrier concentration.

In order to achieve the above object, the present invention uses an electrode material in which 8 to 20 weight percent of Ni is added to an alloy of Au and Si.

An alloy of Au, Si, and Ni (hereinafter abbreviated as Au-Si-Ni).

), an alloy of Au and Si is formed on an n-type crystal substrate by vacuum evaporation, and then a Ni film with a thickness corresponding to a predetermined weight percentage is formed by vacuum evaporation. Alternatively, an alloy in which Au1, 5i and Ni are mixed at a predetermined ratio may be prepared in advance, and the alloy may be formed by a vacuum evaporation method or the like. This Au-Si
- By using a Ni electrode, it is possible to obtain a contact resistance that is lower than that obtained with a conventional electrode made of an alloy of Au and Si over a wide heat treatment temperature range of 420°C to 650°C. Summer.

Examples will be explained below. Example 10 Two filaments for deposition were prepared in the Persian of a vacuum evaporator, the first filament was made of an alloy of Au and Si containing 3.2% by weight of Si, and the second filament was In each case, a predetermined amount of Au is charged.

Thereafter, the first filament and the second filament are deposited on the n-type GaP substrate in this order to form an alloy film of Au and Si having a thickness of 4000 mm and a Si content of about 1% by weight. Next, a Ni film is formed on the substrate to a predetermined thickness by high frequency sputtering. Next, the Au--Si layer and Ni layer on this substrate are processed into a desired shape by photo-etching. Thereafter, this substrate is heat treated at 540° C. for 10 minutes in an N2 gas atmosphere to form an ohmic contact. The solid line in FIG. 1 indicates the Au-S obtained in this way.
12 shows the change in contact resistance of an i-Ni electrode with an n-type GaP substrate with respect to Ni concentration.

Further, the broken line in FIG. 1 shows the change in contact resistance when heat treatment was performed at 440° C. for 10 minutes in the same manner as above. Note that the change in contact resistance referred to here refers to the change in the resistance value between the electrodes when circular electrodes each having a diameter of 100 μm are provided with a distance of 150 μm between the centers. Also, the carrier concentration of the n-type GaP substrate used here is approximately 1.7 x 1017?
-3. From the figure, it is clear that the Ni content is 8.
The Ii contact resistance shows a stable low value in the range of ~20%, and when heat-treated at 540°C, it becomes a value more than 20Ω lower than that of an electrode made only of Au-Si, and
Regarding heat treatment at ℃, electrodes made of only Au-Si do not form ohmic contacts, but they still have high strength.
The same value as in the case of 540°C was obtained.

Figure 2 shows the Au containing 14 weight percent Ni and 1 weight percent Si prepared by the above method.
- It shows the change in contact resistance with respect to the heat treatment temperature of Si-Ni.

As can be clearly seen from the figure, a stable and low contact resistance was obtained at a heat treatment temperature of 420° C. or higher. 65 again
Although ohmic contact can be obtained even with heat treatment at 0° C. or higher, the characteristics of the GaP crystal deteriorate, so it is desirable to perform the heat treatment at 650° C. or lower.
Example 2 Au, S was added to the first filament for deposition in the vacuum evaporator.
A predetermined amount of i and Ni are each charged, and a predetermined amount of Au is charged to the second filament.

After that, the first filament and the second filament were deposited on the n-type GaP substrate in this order, to a film thickness of about 4000.
Xf) Form an Au-Si-Ni film. Next, the Au-Si-Ni film on this substrate was processed into a desired shape by photo-etching, and then etched for 54 hours in a N2 gas atmosphere.
Heat treatment is performed at 0°C to form an ohmic contact. At this time, the content of Si is approximately 1% by weight,
When the Ni content was varied between 3 and 30 weight percent and the change in contact resistance was determined in the same manner as in Example 1, almost the same change as shown in FIG.
, Ni are mixed and deposited, Example 1
It became clear that similar results could be obtained. From the examples described above, it is clear that Au, Si and Ni7
)・By using an electrode made of an alloy, the conventional A
Compared to electrodes made of alloys of u and Si, it has become possible to form electrodes that have much lower contact resistance and provide ohmic contact through heat treatment at a low temperature of 420°C.

Furthermore, the Au-Si-Ni electrode according to the present invention is made of -V group compound semiconductors other than GaP, such as CaAs and GaAsl.
-Applicable to XAlxAs, etc.

[Brief explanation of drawings]

Figure 1 shows Au-Si formed on an n-type GaP semiconductor substrate.
- shows the change in contact resistance with respect to the Ni concentration of the Ni electrode,
Figure 2 is. ．． 2 shows the change in contact resistance between the Au-Si-Ni electrode and the n-type GaP semiconductor substrate with respect to the heat treatment temperature.

Claims (1)

[Claims] 1. In a semiconductor device made of gallium phosphide, the electrode in ohmic contact with the n-type region of the semiconductor substrate is made of a material containing gold, silicon, and nickel, and with a nickel content of 8.
A III-V compound semiconductor device, characterized in that it is formed of an alloy in a range of 20% by weight.