JP3047852B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency device, and more particularly to a structure of a transmitting / receiving amplifier for information communication requiring high output characteristics and low noise characteristics.

[0002]

2. Description of the Related Art In recent years, miniaturized and high-performance mobile phones have been rapidly spreading. Technologies that have greatly contributed to this advance include the development of high-performance batteries and high-performance field-effect transistors, particularly gallium arsenide (GaAs) MES.
There is the development of FET. GaAs MES as device
FETs exhibit excellent performance with respect to high-frequency characteristics such as low-voltage operation, high gain, high efficiency, low noise, and low distortion, and are being used as transmission / reception amplifiers for mobile terminals. Recently, with the advance of technology, an integrated MMIC (Microwave) that forms both a low-noise receiving amplifier section and a high-output transmitting amplifier section on one chip with respect to the conventional hybrid configuration has been developed.
Monolithic IC) has also been developed. The configuration of a conventional transmission / reception amplifier having this structure will be described below with reference to the drawings.

FIG. 3 shows a conventional transmission / reception amplifier integrated MMI.
It is a block diagram showing C. In FIG. 3, reference numeral 30 denotes GaAs.
A high-output amplifier 35 and a low-noise amplifier 36 are formed on the substrate 30. The high output amplifier 35 is a GaAs MESFET having a large gate width.
, And the low-noise amplifier 36 is formed of a GaAs MESFET having a small gate width (for example, K. FUJIMOTO et al., “A high per
performance GaAs MMIC transsc
ever for personal handy
phone system (PHS) ", 25th E
european Microwave Confere
nce, Proceedings, vol. 2, pp.
926-930, 1995).

[0004]

However, in the above-described configuration, when the GaAs substrate 30 has a low thermal conductivity (approximately 0.5 W / cmK), it is necessary to further increase the output of the high-output amplifier. Since the substrate temperature rises and the noise characteristics of the low-noise amplifier part utilizing the high electron mobility (about 6000 cm · cm / Vs) of GaAs deteriorates, a high output type of several W to several hundred W is generated. Integrated MMICs were not feasible with GaAs.

The present invention has been made in view of the above problems, and provides a semiconductor device capable of dramatically increasing the output of a transmission amplifier while minimizing the temperature degradation of the low noise characteristic of the reception amplifier. is there.

[0006]

In order to solve the above problems, the present invention provides a SiC substrate and an AlInGaN or InGaN or AlG substrate formed on the SiC substrate.
an epitaxial film made of aN or GaN;
A semiconductor device includes a power amplifier section formed on an iC substrate and a low noise amplifier section formed on the epitaxial film.

A SiC substrate and an AlInGaN layer formed on the SiC substrate and lattice-matched to SiC.
Or a first epitaxial film made of InGaN or AlGaN or GaN, and AlInGaN or InGaN formed on the first epitaxial film.
Or a second epitaxial film made of AlGaN or GaN , a power amplifier formed on the SiC substrate, and using the first epitaxial film as a Schottky layer of the FET, and a second epitaxial film on the second epitaxial film. A semiconductor device having the formed low-noise amplifier.

According to the present invention, an amplifier section is formed on SiC and a low-noise amplifier section is formed on an epitaxial film (for example, a GaN-based semiconductor material).
High thermal conductivity of C (about 4.9 W / cmK) and high electron mobility of GaN-based material (about 1000 cm · cm / Vs)
, A high-output integrated MMIC is possible.

Further, SiC as a material for high output is G
Since the breakdown electric field is about ten times larger than aAs, the breakdown voltage and the operating voltage of the device can be improved, and the output of several tens of times higher than that of GaAs can be achieved with the effect of the thermal conductivity.

Further, although a GaN-based material is formed on a sapphire substrate or the like because a single crystal substrate does not currently exist, it is possible to form a GaN-based material on a SiC substrate of the present invention. Is obtained. In addition, since the GaN-based material is also a wide-gap semiconductor like SiC, it has a high usable temperature and a small increase in temperature, such as leak current, so that low noise characteristics can be maintained even in a considerably high temperature range.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A field effect transistor according to one embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a transmission / reception integrated MMIC according to a first configuration of the present invention.
FIG. In FIG. 1, reference numeral 10 denotes a SiC substrate. Ga such as AlInGaN on the SiC substrate 10
The epitaxial film 11 is formed using an N-based mixed crystal material. Specifically, an n-type Ga
A channel layer composed of an N layer 11b and undoped Al
A Schottky layer made of a 0.2Ga0.8N layer 11a is formed. The gate electrode 16 is formed on the GaN layer 11a.
s, M having source electrode 16g and drain electrode 16d
An ESFET is formed, and the FET serves as a low-noise amplifier section 16 and has a small gate width.

Reference numeral 15 denotes a high-output amplifier, which is a SiC substrate 10
Inside, an n + source layer, an n + drain layer, and an n-channel layer are formed, and a SiC MESFET having a large gate width is formed.
It is composed of The source layer, the drain layer, and the channel layer are formed by ion implantation of silicon.

As described above, the MESFET for high output is S
By forming on the iC substrate, the high thermal conductivity of SiC can be used, so that an amplifier unit capable of high output can be formed. Further, since a FET can be formed on a GaN-based semiconductor represented by AlInGaN , the high electron mobility (about 1000 cm · cm / Vs) of this material can be utilized.
A low-noise amplifier with good noise characteristics can be formed.

It should be noted that the SiCMEs of the high-output amplifier 15
SiC that can further increase operating voltage instead of FET
It is also possible to use a MOSFET. Also, instead of the GaN-based MESFET in the low noise amplifier section, it is possible to use an AlGaN / InGaN heterostructure FET that can further increase the electron mobility. In this case, the In0.2Ga0.8N layer is used as the channel layer, and the Al0.2G0.8N layer is used.
FIG. 4 shows a structure in which the a0.8N layer is a barrier layer.

FIG. 4 is a structural sectional view of the low noise amplifier section 46 including the heterojunction FET. High output amplifier 15
Is the same as the configuration in FIG. Undoped Al0.2Ga0.8N layer 41, undoped I
n0.1Ga0.9N layer 42, undoped Al0.2G
An a0.8N layer 43 is formed to have a double hetero structure. A Schottky layer composed of an undoped GaN layer 44 including a silicon delta-doped layer is formed on AlGaN 43, and a gate electrode 46g, a source electrode 46s, and a drain electrode 46d are formed on this layer.

According to this structure, electrons can be confined in the well layer.
ET can be used, and the noise characteristics are also improved.

(Embodiment 2) FIG. 2 shows a transmission / reception integrated MMIC according to a second configuration of the present invention.
FIG. In FIG. 2, reference numeral 20 denotes a SiC substrate. On the substrate 20, a first epitaxial film 21 made of an undoped Al0.2Ga0.8N layer is grown.
The AlGaN layer 21 may not be lattice-matched to the SiC substrate, but may be formed using a GaN-based mixed crystal material such as AlInGaN whose composition is selected so as to be lattice-matched to the SiC substrate 20.

A second epitaxial film 22 is formed on the epitaxial film 21 by using a GaN-based mixed crystal material such as AlInGaN . Specifically, an undoped GaN layer 22b, an n-type Al0.2Ga0.8N
The layer 22a is formed.

In the second epitaxial film 22, a low-noise amplifier 26 is formed. The low noise amplifier 26
MESFE using n-type AlGaN layer 22a as a channel layer
T, which has a small gate width.

On the other hand, a heterojunction FET is formed in the high-output amplifier section 25, and the SiC substrate 20 and the AlG
The first epitaxial film 21 is formed in the aN layer 21. Carriers travel on the interface between AlGaN 21 and SiC substrate 20.

In the high-power amplifier section 25, AlInGaN capable of realizing a band gap larger than that of SiC is used.
Since the material is used, the breakdown voltage is improved. The electron mobility is also improved by the GaN-based / SiC heterostructure, and high-frequency power device characteristics such as gain and efficiency are improved as compared with the first embodiment.

Further, similarly to the first embodiment, it is also possible to use a heterostructure FET such as AlGaN / InGaN which can further increase the electron mobility, instead of the GaN-based MESFET in the low noise amplifier.

[0024]

As described above, the semiconductor device according to the present invention has a high power amplifier section formed on a SiC substrate having a thermal conductivity and a dielectric breakdown voltage about 10 times higher than that of GaAs. An ultra-high output type integrated transmission / reception MMI, which was impossible in the past, by integrally forming a low-noise amplifier unit utilizing the high electron mobility of a GaN-based material that can be epitaxially grown on SiC while realizing output.
C is realized. In particular, the realization of a low-noise amplifier using a GaN-based material, which is a wide-gap semiconductor, enables low-noise characteristics to be exhibited even at a high operating temperature. Can carry.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the configuration of a transmission / reception integrated MMIC of the present invention.

FIG. 2 is a sectional view of the configuration of a transmission / reception integrated MMIC of the present invention.

FIG. 3 is a sectional view of the configuration of a conventional MMIC.

FIG. 4 is a cross-sectional view of a configuration of a transmission / reception integrated MMIC of the present invention.

[Explanation of symbols]

 10, 20 SiC substrate 11 Epitaxial film 15, 25, 35 High-power amplifier 16, 26, 36 Low-noise amplifier 21 First epitaxial film 22 Second epitaxial film 30 GaAs substrate

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-9-246471 (JP, A) JP-A-8-264439 (JP, A) JP-A-64-86547 (JP, A) JP-A-9-964 306840 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/337-21/338 H01L 27/095 H01L 27/097 H01L 29/775-29/778 H01L 29/80 -21/812 H01L 21/20 H01L 21/203 H01L 21/205 H01L 23/12 301 H01L 27/04

Claims (3)

(57) [Claims] 1. An SiC substrate, and AlInGaN or I formed on the SiC substrate.
an epitaxial film made of nGaN, AlGaN, or GaN ; a power amplifier formed on the SiC substrate; a low noise amplifier formed on the epitaxial film; the power amplifier and the low noise amplifier Are formed on the same substrate. 2. The semiconductor device according to claim 1, wherein said epitaxial film is a low noise amplifier including an AlGaN barrier layer and an InGaN well layer. 3. An SiC substrate, and AlInGaN or InGaN or AlGaN formed on the SiC substrate and lattice-matched to SiC.
Or a first epitaxial film made of GaN, and AlInG formed on the first epitaxial film.
aN, or InGaN or AlGaN or GaN
A power amplifier section formed on the SiC substrate and using the first epitaxial film as a Schottky layer of a FET; and a low noise formed on the second epitaxial film. A semiconductor device comprising: an amplifier; wherein the power amplifier and the low-noise amplifier are formed on the same substrate.