JPH05121428A - Heterojunction bipolar transistor - Google Patents

Abstract

PURPOSE:To obtain a bipolar transistor using SiC, which excels in its thermal resistance, by constituting it through using an alpha-type SiC layer of unilateral conductivity type as its emitter region, polycrystalline silicon carbide layers of the other conductivity type as its base region, and polycrystalline silicon carbide layers of the unilateral conductivity type as its collector region. CONSTITUTION:A heterojunction bipolar transistor comprises an alpha-type SiC layer 2 of one conductivity type, polycrystalline silicon carbide layers 3 of the other conductivity type, which are laminated on the alpha-type SiC layer 2 of the unilateral conductivity type, and many independent polycrystalline silicon carbide layers 4 of the unilateral conductivity type, which are laminated on the polycrystalline silicon carbide layers 3 of the other conductive type. The heterojunction bipolar transistor is constituted using the alpha-type SiC 2 of the unilateral conductivity type as its emitter region, the polycrystalline silicon carbide layers 3 of the other conductivity type as its base region, and the polycrystalline silicon carbide layers 4 of the unilateral conductivity type as its collector region. Thereby, this bipolar transistor can be used in the place of high temperature, where no conventional device made of silicon and gallium arsenide can be used, as a bipolar transistor which keeps the high-speed quality caused by its heterojunction and excels in its thermal resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to SiC having excellent heat resistance.
And a heterojunction bipolar transistor using.

[0002]

2. Description of the Related Art Bipolar transistors have conventionally been manufactured mainly using silicon and have been widely put into practical use. As a high-speed bipolar transistor, a heterojunction bipolar transistor has been proposed in addition to the silicon bipolar transistor using the Si miniaturization technology, and aluminum gallium arsenide (AlGaAs) / gallium arsenide (GaAs) is proposed.
Research is being conducted mainly. Also, Si and hetero materials
Research on bipolar transistors by bonding with (SiC) is also in progress. However, these bipolar transistors lack heat resistance, and thus cannot be used in a high temperature place.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks and provides a bipolar transistor using SiC having excellent heat resistance.

[0004]

In order to achieve the above-mentioned object, a heterojunction bipolar transistor according to the present invention has a structure in which another conductivity type polycrystalline silicon carbide layer is laminated on one conductivity type α-type SiC layer, and A large number of isolated one-conductivity-type polycrystalline silicon carbide layers are formed on the other-conductivity-type polycrystalline silicon carbide layer,
The one conductivity type α-type SiC layer is formed as an emitter region, the other conductivity type polycrystalline silicon carbide is formed as a base region, and the one conductivity type polycrystalline silicon carbide layer is formed as a collector region.

[0005]

Therefore, the present invention uses polycrystalline silicon carbide in the base region and α-type silicon carbide in the emitter region in order to obtain a bipolar transistor excellent in heat resistance while maintaining high speed due to the heterojunction. , Silicon carbide has a much higher melting point than silicon or gallium arsenide, and
The band gap is 2.8 to 3.3 eV for α-type silicon carbide
Since polycrystalline silicon carbide has a voltage of about 2.2 eV, a heterojunction can be formed. Therefore, it has excellent heat resistance and
It is possible to provide a high speed bipolar transistor.

[0006]

Embodiments of the bipolar transistor of the present invention will be described below with reference to the drawings. The heterojunction bipolar transistor shown in FIG. 1 includes a one-conductivity α-type SiC layer, another conductivity-type polycrystalline silicon carbide layer laminated on the one-conductivity type α-SiC layer, and another conductivity-type polycrystalline silicon carbide layer. And a plurality of isolated one-conductivity-type polycrystalline silicon carbide layers, the one-conductivity-type α-SiC layer being an emitter region, the other-conductivity-type polycrystalline silicon carbide being a base region, and one-conductivity-type polycrystalline carbon carbide. A heterojunction bipolar transistor is formed by using the silicon layer as a collector region.

The procedure for manufacturing the above structure is as follows:
First, P-type polycrystalline silicon carbide is grown on a 6H-type (α-type) silicon carbide substrate by CVD (vapor deposition method). 6 here
H-type silicon carbide is n-type with no addition. Further, in CVD, after the Si substrate is placed in the reaction furnace, disilane (Si ₂
H ₆ ) and acetylene (C ₂ H ₂ ) as source gas, hydrogen (H
₂ ) is flown as a carrier gas to grow a film having a film thickness of about 1000Å by growing at about 1000 ° C. for 20 minutes. B, Al or the like is used as the P-type impurity.

Next, n-type polycrystalline silicon carbide is grown on the same by the same CVD method. P and N are used as the n-type impurities. After that, etching is performed using ordinary photolithography. Further, an oxide film is formed on the entire surface, and a portion to be an electrode is opened by etching using photolithography.

Next, an electrode metal (Al-Si, etc.) is formed in the opening.
Vapor deposition. An npn-type bipolar transistor is formed by using 6H-type silicon carbide as the emitter, P-type polycrystalline silicon carbide as the base, and n-type polycrystalline silicon carbide as the collector.

Further, in the above steps, polycrystalline silicon carbide can be formed by selective growth using a silicon oxide film as a mask. Further, as shown in FIG. 1, a multi-collector bipolar transistor can be formed by providing a plurality of collector portions.

[0011]

As is apparent from the above description, according to the present invention, another conductivity type polycrystalline silicon carbide layer is laminated on one conductivity type α type SiC layer, and a plurality of layers are formed on the surface of the other conductivity type semiconductor layer. One conductivity type polycrystalline silicon carbide region is formed, the conductivity type α-type SiC layer is used as an emitter region, the other conductivity type α-type SiC layer is used as a base region, and one conductivity type polycrystalline silicon carbide layer is used as a collector region. As a bipolar transistor, which maintains high speed due to the heterojunction, and is excellent in heat resistance, it can be used in high temperature places that could not be used with silicon and gallium arsenide devices until now. It has the advantages of high speed and high gain.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a bipolar transistor according to the present invention.

[Explanation of symbols]

 1 n-type 6 HSiC substrate 2 P-type polySiC 3 n-type polySiC 4 insulating film 5 electrode metal

Claims (1)

[Claims] 1. A multi-conductivity polycrystalline silicon carbide layer is laminated on one conductivity type α-type SiC layer, and a large number of isolated one-conductivity type polycrystalline silicon carbide layers are formed on the other conductivity type polycrystalline silicon carbide layer. A heterojunction bipolar transistor having the one conductivity type α-type SiC layer as an emitter region, the other conductivity type polycrystalline silicon carbide as a base region, and the one conductivity type polycrystalline silicon carbide layer as a collector region.