JPH08330240A - Preparation of semiconductor epitaxial growth layer - Google Patents

Abstract

PURPOSE: To obtain a preparation of a semiconductor epitaxial growth layer which can realize easily a semiconductor device which has a long-lifetime element and high reliability. CONSTITUTION: In regard to a semiconductor epitaxial growth layer for a heterojunction bipolar transistor formed by a growth according to an MOCVD method, growth temperatures of a base layer 3 and an emitter layer 4 are made to be 600-650 deg.C and from the growth temperature of the base layer to 700 deg.C respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor epitaxial growth layer for a heterojunction bipolar transistor grown by MOCVD.

[0002]

2. Description of the Related Art When a semiconductor device such as an AlGaAs / GaAs heterojunction bipolar transistor (HBT) is formed, the semiconductor epitaxial growth layer has conventionally been
A semiconductor epitaxial growth layer having a multi-layer structure grown mainly by the MOCVD method has been used. MOCVD
Carbon-doped base AlGaAs / GaA
When growing an epitaxial growth layer for sHBT, a collector buffer layer and a collector layer are first grown on a GaAs substrate, and then a base layer and an emitter layer are sequentially grown. At this time, in order to dope the base layer with a high concentration of carbon without drastically changing the normal growth conditions such as the V / III ratio, which is the composition ratio of the group V element and the group III element,
It is common to grow at a relatively low temperature of about 550 to 590 ° C. and to grow the emitter layer at a relatively low temperature of about 550 to 590 ° C. in order to realize a device having a high current amplification factor of 100 or more. It was

[0003]

However, in the case of the semiconductor device epitaxially grown by the above-mentioned conventional technique, although the HBT current amplification factor in the initial stage is relatively high, the device characteristics are relatively short. There was a problem of deterioration.

It is an object of the present invention to obtain a method for manufacturing a semiconductor epitaxial growth layer, which can easily realize a semiconductor device having a long device life and high reliability.

[0005]

The above-mentioned object is to achieve MOCVD.
In the method for manufacturing a semiconductor epitaxial growth layer for a heterojunction bipolar transistor grown by the method, the growth temperature of the base layer is 600 ° C. or higher and 650 ° C. or lower,
In addition, the growth temperature of the emitter layer is achieved by setting the growth temperature of the base layer to 700 ° C. or higher.

[0006]

In the HBT using the semiconductor epitaxial growth layer grown at a relatively low temperature as described above, the device characteristics deteriorate in a short time even though the initial current amplification factor is relatively high. In order to prevent this, when the growth temperature of the semiconductor epitaxial growth layer is changed in the range of 500 ° C. to 700 ° C. and the epitaxial layer is grown, a positive correlation is found between the growth temperature of the base layer and the emitter layer and the device life. It became clear that there exist. That is, it was revealed that the semiconductor device manufactured using the semiconductor epitaxial growth layer in which the growth temperature of the base layer and the emitter layer is high has a longer element life. It is considered that this is because the semiconductor layer grown at a higher temperature has less recombination centers and has better crystal quality.

The growth temperature of the base layer is 600 ° C.
If it is less than 600 ° C., the device life is shorter than that at 600 ° C. or more, and if it exceeds 650 ° C., it is difficult to dope the desired high-concentration carbon, and practical initial characteristics cannot be obtained. Further, when the growth temperature of the emitter layer is lower than the growth temperature of the base layer, the device life is shorter than when the growth temperature of the base layer is higher than the growth temperature of the base layer, and the growth temperature of the emitter is 70%.
When the temperature exceeds 0 ° C, the initial value of the current amplification factor is low and the initial characteristics are not practical.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a diagram showing a change in current amplification factor of a semiconductor device formed by using a semiconductor epitaxial growth layer manufactured according to the present invention, and FIG. 2 is a cross section showing an embodiment of a heterojunction bipolar transistor using the semiconductor epitaxial growth layer according to the present invention. It is a figure.

An HBT as shown in FIG. 2, for example, was manufactured using a semiconductor epitaxial growth layer formed according to the present invention with the growth temperatures of the base layer and the emitter layer being 600 ° C. and 650 ° C., respectively. In FIG. 2, an n (+) GaAs collector.
Buffer layer 1, i-GaAs collector layer 2, p-GaA
s base layer 3, n-AlGaAs emitter layer 4 and n
The (+) GaAs emitter cap layer 5 is grown.
The growth temperatures of the base layer 3 and the emitter layer 4 at this time are 600 ° C. and 650 ° C., respectively. The semiconductor crystal layer surface of the above growth is selectively etched to form an emitter mesa, a base mesa, and a collector mesa.
At this time, the recombination current is suppressed by leaving a part of the emitter layer 4 in the external base region. A collector electrode 6, a base electrode 7 and an emitter electrode 8 are formed on the collector / buffer layer 1, the base layer 3 and the emitter cap layer 5, respectively. The portions other than the above-mentioned electrode portions are covered with the SiN film 9.

FIG. 1 is a diagram showing the change over time in the current amplification factor of the HBT. For reference, FIG. 1 also shows, for comparison, the case of an HBT manufactured using a semiconductor epitaxial growth layer grown by a conventional method, in which the growth temperature of the base layer is 500 ° C. and the growth temperature of the emitter layer is 590 ° C. Is shown. In the case of the HBT using the semiconductor epitaxial growth layer grown by the manufacturing method of the present invention, the HBT using the conventional semiconductor epitaxial growth layer is used.
It is clear from the figure that it has a life of 10 times or more as compared with. According to the present invention, as described above, a semiconductor device having much higher reliability than that of the conventional element can be easily realized without changing the manufacturing process after crystal growth in the production of the conventional element. The advantage is that It should be noted that when the growth temperature of the base layer is increased as in the above-mentioned embodiment, the carrier concentration in the base layer tends to decrease slightly, but this is devised for other growth conditions such as V / III ratio. There is no particular problem because it can be compensated for. Further, when the growth temperature of the emitter layer is increased, the initial value of the current amplification factor in the HBT tends to be slightly lower than that in the case of low temperature growth, but the value of about 40 or more required for normal circuit operation is There is no practical problem because it can be secured.

Experiments similar to those in the above-described examples were conducted on semiconductor devices formed by using various semiconductor crystal deposited films, and the growth temperature of the base layer was 600 ° C. or more and 650 ° C.
In the following, in the semiconductor device formed by using the semiconductor epitaxial growth layer in which the growth temperature of the emitter layer is higher than the growth temperature of the base layer and lower than 700 ° C., it is possible to confirm the same effect as that of the above embodiment. did it.

In this embodiment, AlGaAs / GaA is used.
The s-based HBT was explained, but Al as the base layer was used.
The present invention is effective and the same effect can be obtained even when AlGaAs having a relatively small composition of about 10% is used.

[0013]

As described above, the method for manufacturing a semiconductor epitaxial growth layer according to the present invention is the same as the method for manufacturing a semiconductor epitaxial growth layer for a heterojunction bipolar transistor grown by MOCVD, and the growth temperature of the base layer is 600 ° C. or more and 650 ° C. And the growth temperature of the emitter layer is equal to or higher than the growth temperature of the base layer.
When the temperature is 0 ° C. or less, the semiconductor epitaxial growth layer produced under the above growth temperature condition has an effect that a semiconductor device having a long device life and high reliability can be easily realized.

[Brief description of drawings]

FIG. 1 is a diagram showing changes in current amplification factor of a semiconductor device formed using a semiconductor epitaxial growth layer manufactured according to the present invention.

FIG. 2 is a diagram showing an example of a heterojunction bipolar transistor using semiconductor epitaxial growth of the present invention.

[Explanation of symbols]

 2 i-GaAs collector layer 3 p-GaAs base layer 4 n-AlGaAs emitter layer

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor epitaxial growth layer for a heterojunction bipolar transistor grown by MOCVD, wherein the growth temperature of the base layer is 600 ° C. or higher and 650 ° C. or lower, and the growth temperature of the emitter layer is the base. A method for producing a semiconductor epitaxial growth layer, characterized in that the temperature is 700 ° C. or lower at a layer growth temperature or higher.