JPH08236549A - Semiconductor device - Google Patents

Abstract

PURPOSE: To prevent a surge from intruding into an electronic circuit by a method wherein a first conductive region, which is formed between the circuit and an input/output terminal, and a second conductive region, which is formed between the circuit and a power terminal, are monolithically integrated so that the withstand voltages of the first and second conductive regions to a conductive substrate are made lower than that of the circuit. CONSTITUTION: A semi-insulative crystal layer 2 is grown on a conductive substrate 1, an electronic circuit 3 is formed in the layer 2 and an input/output terminal 4 and a power terminal 5 are provided. Moreover, a conductive region 6 is formed between the terminal 4 and the circuit 3 and a conductive region 7 is formed between an terminal, which is applied a surge through an external terminal, such as the terminal 5, and the circuit 3. The distances (d1 ) and (d2 ) between the substrate 1 and the regions 6 and 7 are selected so that the withstand voltages of the regions 6 and 7 to the substrate 1 are made lower than that of the circuit 3. Thereby, before the circuit 3 is broken or malfunctioned, a current flows between the regions 6 and 7 and the substrate 1 and the surge applied to the terminal can be absorbed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device which operates stably under conditions such as engine / motor control for which surge voltage is generated.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
For example, "Electronic Technology 1991-5.P. 61-67"
Was disclosed in. As shown in this document, in an electronic circuit which is used under conditions where a surge voltage is generated and applied to the circuit, a varistor is inserted between the electrode to which the surge voltage is applied and ground in order to absorb the surge. The method is usually done.

In this case, the varistor has a high resistance up to a certain voltage, but when a voltage exceeding that voltage is applied across the terminals, the varistor has a low resistance and short-circuits the surge voltage to protect the circuit. Further, a Zener diode having similar characteristics may be used instead of the varistor.

[0004]

However, in the conventional method described above, the surge voltage can be stably absorbed, but such an element must be provided externally to the electronic circuit to be protected. It has been difficult to monolithically form an integrated circuit by integrating with a semiconductor circuit.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above problems and to provide a semiconductor device which is monolithically integrated with a semiconductor circuit having a function capable of absorbing a surge voltage.

[0006]

In order to achieve the above object, the present invention provides a semiconductor device comprising: (1) a conductive substrate; a semi-insulating crystal layer grown on the conductive substrate; An electronic circuit formed in the insulating crystal layer, an input / output terminal and a power supply terminal connected to the electronic circuit, a first conductive region formed between the electronic circuit and the input / output terminal, and the electronic circuit A second conductive region formed between power supply terminals is provided, and the breakdown voltage between the first conductive region and the second conductive region and the conductive substrate is monolithically integrated so as to be lower than the breakdown voltage of the electronic circuit. It is something that is done.

(2) A conductive substrate, a semi-insulating crystal layer grown on the conductive substrate, an active element formed on the semi-insulating crystal layer, and at least the first element formed on the active element. And a second terminal, a first conductive region connected to the first terminal of the active element, and a second conductive region formed between the active element and the second terminal, The breakdown voltage between the first and second conductive regions and the conductive substrate is monolithically integrated so as to be lower than the breakdown voltage of the active element.

(3) In the semiconductor device described in (1) or (2) above, the thickness of the semi-insulating crystal layer is adapted to the surge voltage. (4) In the semiconductor device according to (2), the active element is a field effect transistor, the first conductive region is a source or a drain, and the second conductive region is a drain or a source.

(5) In the semiconductor device described in (4) above, the field effect transistor is a Schottky gate field effect transistor.

[0010]

[Action]

(1) According to the semiconductor device of the first aspect, since the surge applied to the electronic circuit is absorbed in the chip and the surge is prevented from entering the electronic circuit, the electronic circuit is not destroyed and operates normally. In addition, it is not necessary to externally attach the surge absorbing circuit to the integrated circuit, and the surge absorbing circuit can be configured as a monolithic integrated circuit.

Further, by only controlling the distance between the conductive region that absorbs the surge and the substrate, it is possible to easily construct a semiconductor device that can cope with various surge voltages. (2) According to the semiconductor device of the second aspect, since the active element itself forming the integrated circuit can be provided with surge resistance, it is not necessary to take a surge countermeasure outside the integrated circuit, and the integrated circuit is monolithically integrated. A semiconductor device having surge resistance can be configured.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a sectional view of a semiconductor device having a surge absorbing function according to a first embodiment of the present invention. As shown in this figure, a semi-insulating crystal layer 2 is grown on a conductive substrate 1, and an electronic circuit 3 is formed on the semi-insulating crystal layer 2. Then, a terminal to which a surge is applied from the outside such as the input terminal or the output terminal 4 and the power supply terminal 5 is provided, and a surge is applied from the outside such as the conductive region 6 and the power supply terminal 5 between the input terminal or the output terminal 4 and the electronic circuit 3. A conductive area 7 is provided between the applied terminal and the electronic circuit 3.
Are formed and electrically connected to each terminal. The conductive region 6 or 7 may be formed of a conductive crystal or a metal.

Then, the conductive region 6 or 7 and the conductive substrate 1
The distance d ₁ or d ₂ between the conductive substrate 1 and the conductive region 6 or 7 is selected so that the withstand voltage value is lower than the withstand voltage of the electronic circuit to which each terminal is connected. Taking GaAs as a semi-insulating crystal and an n-type GaAs substrate as a conductive substrate, for example, the conductive region 6 or 7 for d ₁ and d ₂ is 1 μm.
The breakdown voltage between the conductive substrate 1 and the conductive substrate 1 is about 20V. In this case, the conductive substrate 1 is basically grounded before use.

In this structure, as long as a semi-insulating crystal is obtained, the crystal material does not need to be the same, and the conductive substrate and the crystal above it need not be of the same type. Furthermore, it does not depend on the element that constitutes the electronic circuit. When a surge is applied to the input terminal or output terminal 4, the power supply terminal 5 or the like of the integrated circuit configured as described above, the conductive region 6 or 7 connected to each terminal and the conductive substrate 1 are higher than the withstand voltage of the electronic circuit 3. Since the withstand voltage is lower, a current flows between the conductive region 6 or 7 and the conductive substrate 1 to absorb the surge applied to the terminal before the electronic circuit 3 is destroyed or malfunctions.

The structure of the integrated circuit having a surge absorbing function has been described above. With this structure, an integrated circuit having a high surge withstand voltage can be easily realized.
It is possible to stably operate in a portion where a surge such as motor control occurs or a portion where noise is large. FIG. 2 is a sectional view of a semiconductor device having a surge absorbing function showing a second embodiment of the present invention.

First, a film thickness d is formed on an n-type or p-type conductive substrate (for example, GaAs substrate or Si substrate) 11.
_One semi-insulating crystal layer (eg, GaAs) 12 is grown. A Schottky gate field effect transistor 13 (hereinafter, MESFET) is formed on the semi-insulating crystal layer 12, and an integrated circuit is configured by using this as an active element. Reference numeral 17 is a source electrode, 18 is a gate electrode, and 19 is a drain electrode. At this time, the drain region 16 of the MESFET 13,
When the withstand voltage between the source regions 14 is V ₁ , the film thickness d ₃ of the semi-insulating crystal layer 12 is such that the withstand voltage V ₂ between the drain regions 16 and the conductive substrate 11 is V ₂ <V _1. The depth d ₄ of the drain region 16 is formed. Then, the conductive substrate 11 is grounded. The breakdown voltage V ₂ between the drain region 16 and the conductive substrate 11 varies depending on the crystal material, but when formed by adding Cr, V or the like to GaAs as an example, the breakdown voltage V ₂ becomes a value of d ₃ -d ₄ . On the other hand, about 20V /
μm.

The drain region 1 of the MESFET 13
It goes without saying that the withstand voltage V ₁ between the 6 and source regions 14 is higher than the voltage at which the circuit operates normally. In the case where the integrated circuit is configured as described above, when the surge superimposed on the power supply line is applied to the drain region 16, the voltage between the drain region 16 and the conductive substrate 11 is higher than the drain-source breakdown voltage V _{1 of} the MESFET 13. for towards the breakdown voltage V ₂ is small, a surge voltage is applied, MESFET13 flows through the conductive substrate 11 current before not work properly, to absorb surges, protected from destroy MESFET13 as element . In addition, in FIG. 2, 15 is a channel part.

The element structure having resistance to surge voltage has been described above.
It is possible to configure a monolithically integrated semiconductor device that operates stably in a circuit in a portion where a surge occurs such as motor control or in a circuit used in a portion where noise is large. The present invention is not limited to the above-mentioned embodiment, and various modifications can be made based on the spirit of the present invention.
They are not excluded from the scope of the present invention.

[0019]

As described in detail above, according to the present invention, the following effects can be achieved. (1) According to the invention described in claim 1, in order to absorb the surge applied to the electronic circuit in the chip and prevent the surge from invading the electronic circuit, the electronic circuit is not destroyed and only operates normally. Moreover, it is not necessary to externally attach the surge absorbing circuit to the integrated circuit, and the surge absorbing circuit can be configured as a monolithic integrated circuit.

Further, by only controlling the distance between the conductive region that absorbs the surge and the substrate, it is possible to easily construct a semiconductor device that can cope with various surge voltages. (2) According to the invention as set forth in claim 2, since the active element itself constituting the integrated circuit can be provided with surge resistance, it is not necessary to take a surge countermeasure outside the integrated circuit, and the surge integrated monolithically is provided. A durable semiconductor device can be formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductor device having a surge absorbing function showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a semiconductor device having a surge absorbing function showing a second embodiment of the present invention.

[Explanation of symbols]

 1, 11 conductive substrate 2, 12 semi-insulating crystal layer 3 electronic circuit 4 input terminal or output terminal 5 power supply terminal 6, 7 conductive region 13 Schottky gate field effect transistor 14 source region 15 channel part 16 drain region 17 source electrode 18 Gate electrode 19 Drain electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Ueda 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (5)

[Claims] 1. A conductive substrate, (b) a semi-insulating crystal layer grown on the conductive substrate, (c) an electronic circuit formed on the semi-insulating crystal layer, and (d). ) An input / output terminal and a power supply terminal connected to the electronic circuit, (e) a first conductive region formed between the electronic circuit and the input / output terminal, and (f) formed between the electronic circuit and the power supply terminal. And (g) monolithically integrating such that the breakdown voltage between the first and second conductive regions and the conductive substrate is lower than the breakdown voltage of the electronic circuit. A semiconductor device characterized by: 2. (a) a conductive substrate, (b) a semi-insulating crystal layer grown on the conductive substrate, (c) an active element formed on the semi-insulating crystal layer, and (d) ) At least a first terminal and a second terminal formed in the active element, (e) a first conductive region connected to the first terminal of the active element, (f) the active element and A second conductive region formed between two terminals, and (g) a breakdown voltage between the first conductive region and the second conductive region and the conductive substrate is lower than a breakdown voltage of the active element. A semiconductor device characterized by being monolithically integrated into a semiconductor device. 3. The semiconductor device according to claim 1, wherein the thickness of the semi-insulating crystal layer corresponds to a surge voltage. 4. The semiconductor device according to claim 2, wherein the active element is a field effect transistor, the first conductive region is a source or a drain, and the second conductive region is a drain or a source. 5. The semiconductor device according to claim 4, wherein the field effect transistor is a Schottky gate field effect transistor.