JPS6024592B2 - Manufacturing method of wide-gap emitter transistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Ga ship, Ga... This article relates to the structure of an Nx wide gap emitter transistor and its manufacturing method.

Germanium, especially silicon, is the most common material for making transistors.

On the other hand, gallium silicide (GaAs) has a higher forbidden band energy than silicon or germanium, so the temperature at which it becomes an intrinsic semiconductor is high. Therefore, it is expected that GaAs transistors can be used at high temperatures and provide high output. Also Ga. Since the mobility of electrons in the whistle is high, it can be expected to have good high speed and high frequency characteristics.
Despite these promising features, transistors made from Ga have not been put into practical use because it is difficult to form bases and emitters, which can be easily achieved with silicon. Furthermore, the idea of increasing the injection efficiency of transistors by using wide-gap emitters using heterojunctions was already pointed out soon after the transistor was invented, but it has not yet been fully implemented. .

This is because a good heterojunction could not be obtained. The object of the present invention is to provide a transistor which does not have the drawbacks of the conventional elements mentioned above, that is, has high emitter injection efficiency.
The object of the present invention is to provide a GaAs heterojunction transistor that has excellent high speed performance, can obtain high output, and can be used up to high temperatures.

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1a shows a cross section of an embodiment of the present invention. Figure b shows the surface of this transistor.
To make a transistor with this structure, first, on an n-type Ga pseudo substrate 1, an n-type Ga substrate 2, a p-type Ca pseudo 3, an n-type Gao substrate. 8
A.I.O. 2As4 is grown continuously by liquid phase epitaxial method. The thickness of these layers is the same as that of the initial n-type GaA
s has three peaks, the base p-type Ga pseudo layer has a thickness of 0.2 μm, and the final emitter layer has two peaks. A first n-type approximately aAs layer 2 is grown to improve the reproducibility of the base layer thickness.
This is because if the p-type GaAs layer 3 serving as the base layer is grown directly on the substrate, it becomes difficult to control the thickness. The emitter layer is generally made of n-type Ga, with Nx layers grown, but x was set at 0.2 here. A sufficient effect is expected even if this value is a little smaller. Then, as shown in Figure 1a, p
Layer 5 is formed by selective diffusion of zinc. Diffusion is carried out to a depth sufficient to reach the p-type GaAs layer 3 serving as the base layer. As shown in the figure, we actually performed diffusion to the extent that it slightly passed the base. After completion of the diffusion, contacts 6 and 7 to the emitter and base were made as shown in FIG. 1, and a contact 8 to the collector was made from the n-type Ga substrate to form a transistor. FIG. 1b is a plan view of this transistor, and the same parts as in FIG. 1a are designated by the same reference numerals.

Note that 10 indicates a pad for an emitter electrode. When the ground emitter current amplification factor 3 of this transistor was measured, a high value of B=500 was obtained.

It also has the characteristics of high speed. As in this example,
Since the emitter is formed using the semiconductor 4 which has a higher forbidden band energy than the semiconductor forming the base 3, there is no injection of holes from the base region to the emitter, and as a result, in the current passing through the emitter junction. The proportion occupied by electron current is improved.

That is, emitter efficiency can be increased. Furthermore, in the present invention, since the base region and the base contact region are provided in the same epitaxial layer, the effective series resistance connected to the base is low, which is favorable for the high frequency characteristics of the transistor. .

As described above, the transistor according to the present invention has the characteristics of high current amplification, excellent high speed, high output, and high temperature operation, and has great practical value.

Note that although the embodiment deals with npn transistors, it is of course possible to use pnp transistors as well.

In addition, GaAs in the examples can be replaced with Ga, NA1xAs, and compound semiconductors based on Ga, *AIxAs semiconductors, such as Ga, AlxA
It is also possible to replace it with s, -yPy (0<y<1), etc.

Furthermore, the method of the present invention is extremely practical in that it can be applied to a method for manufacturing Ga-lees ICs, and new functions can be provided by combining it with light-emitting diodes.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is an n-type Ga carrier substrate, 2 is an n-type GaAs growth layer, 3 is a p-type GaAs layer, and 4 is an n-type GaO layer. 8AIO. 2
As, 5 is p-type Gao. &ri is 0.2As. 6, 7, and 8 are emitter, base, and collector electrodes, respectively. 10' is a pad for emitter electrode.

Claims (1)

[Claims] 1 Ga_1_-_xAl_xA on a predetermined semiconductor substrate
A semiconductor comprising an s (0≦x≦1)-based compound semiconductor or a compound semiconductor based on the semiconductor, having a collector layer, a base layer, and a conductivity type opposite to the base layer, and constituting the base layer. A step of laminating and growing a plurality of layers made of a semiconductor having a higher forbidden band energy and including at least an emitter layer forming a heterojunction with the base layer, reaching at least the base layer from a predetermined region on the surface of the grown layer. 1. A method for manufacturing a wide gap emitter transistor, comprising the step of selectively diffusing impurities of the same conductivity type as the base layer to a depth to form a base contact region.