JP2001085629A - Semiconductor device - Google Patents

Abstract

(57) [Abstract] [Problem] Low cost, fast detection speed, high accuracy,
To provide a semiconductor device with a temperature detection sensor capable of extracting a temperature signal to the outside. An upper arm pn diode (6) is used as a temperature detection center of an upper arm IGBT (1), and a constant current is supplied to the pn diode (6) by a constant current circuit (10).
The on-voltage of the n-diode 6 is used as a temperature signal,
From the outside. This pn diode 6 is an IGB
The cathode 8 of the pn diode 6 is connected to the emitter terminal of the IGBT 1 by setting the thickness of the oxide film on the semiconductor substrate on which the T1 is formed via an oxide film so as not to cause dielectric breakdown at the rated voltage of the IGBT. Without connecting with E,
The temperature signal can be easily taken out to the outside by removing the level down circuit which has been conventionally required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device with a temperature detection sensor.

[0002]

2. Description of the Related Art IGBTs (insulated gate bipolar transistors), power MOSFETs (MOS field effect transistors) and BJTs (bipolar transistors)
Power semiconductor devices such as
The element generates heat due to the generated loss. A diode or a resistor is formed on a semiconductor substrate on which these power semiconductor elements are formed via an oxide film, and the temperature during operation of the power semiconductor element is detected using the diode or the resistor as a temperature detection sensor. . When used as a temperature detection sensor, a diode uses a change in on-voltage due to temperature, and a resistor uses a change in resistance value due to temperature.

In temperature detection, a reference potential (potential corresponding to ground) of an external circuit of an output destination such as a microcomputer.
And a power semiconductor element (for example, IGB)
The case where the reference potential of T) is different will be described.

FIG. 3 is a circuit diagram showing a normal arm, a series arm composed of power semiconductor elements, a load, and a gate control circuit. This circuit includes an upper arm IGBT101 on the high potential side and a lower arm IGBT1 on the low potential side.
11, freewheel diodes 105 and 115 connected in anti-parallel to these IGBTs 101 and 111, upper arm gate control circuit 109, lower arm gate control circuit 11
9 and a load 124. Upper arm IG
The collector 102 of the BT 101 is connected to the high potential side 13 of the main power supply.
1 and the emitter 113 of the lower arm IGBT 111.
Is connected to the ground GND. Also, upper arm IGBT
The emitter 103 of the lower arm 101 and the collector 112 of the lower arm IGBT 111 are connected to each other.
Connect with The other end of the load 124 is connected to the middle point of another series arm (not shown).

In the case of this circuit, the upper arm IGBT 101
The reference potential (potential of the emitter 103) becomes VOUT, and this potential always fluctuates during the switching operation of the upper and lower arm IGBTs 101 and 111 and the state of the load 124. On the other hand, the reference potential (potential of the emitter 113) of the lower arm IGBT 111 becomes the ground (GND) and does not change. Next, a case where the temperatures of the IGBTs 101 and 111 are detected will be described. In addition, 10 in the figure
Reference numerals 4 and 114 denote gates of the upper and lower arm IGBTs.

FIG. 4 shows a conventional inverter circuit having a temperature detecting circuit. The temperature detection circuit is a constant current circuit 11
0, 120 and pn diode 10 serving as temperature detection sensor
6, pn diodes 106, 1
Reference numeral 16 is formed on a semiconductor substrate on which the IGBTs 101 and 111 are formed via an insulating film. This pn diode 10
6, 116 anode 107, 117 and cathode 1
08 and 118 are connected to the upper and lower arm gate control circuits 209 and 219, and the cathodes 108 and 118 of the upper and lower arm pn diodes are connected to the emitters 103 and 113 of the upper and lower arm IGBTs, respectively. The constant current circuit 110 in these gate control circuits 209 and 219,
A constant current is supplied to the pn diodes 106 and 116 from 120 (illustrated outside). IGBT101,
When the temperature increases due to the operation of 111, the forward voltage drop (ON voltage) of pn diodes 106 and 116 decreases.
The potentials of the anodes 107 and 117 of the pn diodes are transmitted to the gate control circuits 209 and 219, and it is detected that the IGBTs 101 and 111 are overheated at the level of this potential, and the gate signals of the IGBTs 101 and 111 are stopped. IGBT1 by reducing the voltage of the gate signal
01 and 111 are prevented from overheating.

However, in this circuit, the upper arm IGBT
The reference potential (cathode potential) of the temperature signal 101 is several hundred volts
Therefore, it is difficult to convert this temperature signal to a GND reference signal as an alarm signal or the like and output it to the outside. The temperature signal is the anode of the pn diode.
Refers to the voltage between the cathodes (ON voltage).

In order to output the temperature signal as an alarm signal to the outside, the reference potential of the temperature signal of the upper arm IGBT 101 is converted to a ground potential, and the upper and lower arm IGBTs are converted.
It is necessary to set the reference potentials of the temperature signals 101 and 111 to a common ground GND. Next, a circuit for extracting the temperature signal to the outside will be described.

FIG. 5 shows another conventional inverter circuit having a temperature detecting circuit. This is the upper arm IGBT10
The potential of the anode 107 of the upper arm pn diode 106 serving as the first temperature sensor is once introduced into the gate control circuit 309, and the gate control circuit 309 and the level down circuit 30
This is a circuit for taking out a temperature signal from the upper arm temperature signal terminal 309 to the outside via the “0”. The level down circuit 300 converts the cathode potential (reference potential) of the upper arm pn diode 106 from several hundred volts to the ground potential, and the ground potential (temperature signal) common to the cathode potential (reference potential) of the lower arm pn diode 116. By setting the potential of the ground terminal 323), each anode 10
7 and 117 can be taken out as a temperature signal to monitor the temperature. This temperature signal is transmitted to the gate control circuits 309 and 319 via an overheat prevention circuit and a level shift circuit (not shown), and
The overheating of the IGBTs 101 and 111 can be prevented by turning off the gates of the 101 and 111 or reducing the gate voltage. Although not shown here, the level down circuit 300 includes two operational amplifiers and a high withstand voltage MOSF as disclosed in Japanese Patent Application Laid-Open No. H10-123184.
This is a complicated circuit composed of ET and resistors. The level down circuit 300 of this circuit may be a photocoupler circuit.

FIG. 6 is a cross-sectional view of a main part when the circuit of FIG. 5 is formed on a semiconductor substrate. Here, the upper arm IGB
FIG. 3 shows a cross-sectional view of a main part of T101 and an upper arm pn diode 106. A p-well region 61 is formed in a surface layer of an n-semiconductor substrate, an n-emitter region 63 is formed in a surface layer of the p-well region 61, and a p-well region sandwiched between the n-emitter region 63 and the n ⁻ base region 61 is formed. A gate oxide film 64 on 62
Is formed to form the gate electrode 65. An emitter electrode 66 is formed on the n emitter region 63. On the other hand, a p collector region 67 is formed in a surface layer on the other main surface of the n semiconductor substrate,
A collector electrode 68 is formed on p collector region 67.
Collector electrode 68, emitter electrode 66 and gate electrode 65 are connected to collector terminal C, emitter terminal E and gate terminal G, respectively. Thus, the upper arm IG
The BT 101 is formed. n away from p-well region 62
A p region 71 is formed in a surface layer of a semiconductor substrate, and the p region 71 is formed.
An upper arm pn diode 10 of a thin film with an insulating film
6 is formed. This upper arm pn diode 106
It is composed of a p anode region 73, an n cathode region 74, an anode electrode 75, and a cathode electrode 76. The upper arm pn diode 106 is a temperature detection sensor for the upper arm. Cathode 10 of upper arm pn diode 106
8 and the emitter terminal E of the upper arm IGBT 101 are connected. Anode 107 of upper arm pn diode 106
Are the constant current circuit 120 and the upper arm gate control circuit 309
The upper arm gate control circuit 309 is connected to the upper arm temperature signal terminal 321 via the level down circuit 300. The emitter terminal E of the upper arm IGBT 101 is connected to the collector terminal of the lower arm IGBT (not shown), and serves as a middle point between the upper and lower arms, and this point also serves as an output point.

[0011]

A few hundred volts from the GND potential
In order to monitor the temperature of the upper arm IGBT or the like having the reference potential fluctuating as described above, the level down circuit 300, which has conventionally been indispensable, includes two operational amplifiers, a high-voltage MOSFET, and a resistor as described above. This is a complicated circuit configured, so that the detection speed is low, the detection accuracy is poor due to the offset voltage and resistance variation of the operational amplifier, and the cost is increased by adding a level down circuit. Further, when a photocoupler circuit is used instead of the level down circuit 300, there is a problem in terms of detection accuracy and cost.

An object of the present invention is to provide a semiconductor device with a temperature detection sensor capable of taking out a temperature signal to the outside at a low cost, at a high detection speed, with high accuracy, by solving the above-mentioned problems.

[0013]

In order to achieve the above object, a temperature detection sensor formed on a main surface of a semiconductor substrate is connected to a circuit system having a reference potential different from a reference potential of a circuit system of the semiconductor substrate. It is configured to be electrically connected.

The temperature detection sensor may be formed on the semiconductor substrate via an insulating film.

[0015] The temperature detection sensor may be a semiconductor element or a resistor.

It is preferable that the semiconductor element is a diode.

Preferably, the insulating film is an oxide film.

The thickness t (μm) of the oxide film is the maximum value V of the potential difference between the semiconductor substrate and the temperature detection sensor.
_MAX (V),

[0019]

It is preferable that the relationship t ≧ V _MAX / 800 is satisfied.

A high-potential upper-arm main semiconductor element connected to the high-potential side of the main power supply, and a lower-arm main semiconductor element connected to the low-potential side of the main power supply. Among the semiconductor elements, it is preferable that the substrate includes the upper arm main semiconductor element.

[0021] The temperature detection sensor may be a first conductivity type first sensor.
It is preferable that the insulating layer is formed via an insulating film in the second region of the second conductivity type selectively formed on the region or on the surface layer of the first region.

As described above, the thickness of the oxide film is optimized,
By separating the emitter of the upper arm IGBT and the cathode of the upper arm pn diode, the reference potential of the temperature signal of the upper and lower arm IGBTs can be adjusted to the common ground without a level down circuit. By setting a common ground potential, the output voltages (pn
Diode voltage) can be extracted as a temperature signal. By eliminating the need for a level down circuit or a photocoupler circuit, it is possible to take out a temperature signal externally at low cost, at a high detection speed, with high accuracy.

[0023]

FIG. 1 is an inverter circuit including a semiconductor device having a temperature detection sensor according to a first embodiment of the present invention and having a circuit for extracting a temperature signal to the outside.

This inverter circuit comprises an upper arm IGBT1 on the high potential side, a lower arm IGBT11 on the low potential side, freewheel diodes 5, 15 connected in antiparallel to these IGBTs, an upper arm gate control circuit 9, a lower arm gate It comprises a control circuit 19 and a load 24.
The collector 2 of the upper arm IGBT 1 is connected to the collector terminal C, and the collector terminal C is connected to the high potential side 31 of the main power supply. The emitter 13 of the lower arm IGBT 11 is connected to the low potential side 32 of the main power supply, and the low potential side 32 is connected to the ground GND.
Connect to The emitter 3 of the upper arm IGBT 1 is connected to the collector 12 of the lower arm IGBT 11 via the emitter terminal E, and this connection point is connected to the middle point 33 of the series arm.
, Becomes the output point of the inverter circuit, and is connected to the load 24. The other end of the load 24 is connected to the midpoint of another series arm (not shown).

The temperature detection circuits of the upper and lower arms are:
The lower arm constant current circuits 10 and 20 and the upper and lower arm pn diodes 6 and 16 serving as upper and lower arm temperature detection sensors are formed. These pn diodes 6 and 16 form an IGBT as shown in FIG. Formed on a semiconductor substrate to be formed via an insulating film. The anodes 7, 17 of these pn diodes 6, 16 are connected to the upper and lower arm constant current circuits 10, 2,
0, and the upper and lower cathodes 8 and 18 are connected to the lower potential side 32 of the main power supply, that is, the ground GND. Further, the lower arm gate control circuit 19 and the upper and lower arm constant current circuits 1
0, 20, and the anodes 7, 17 and the cathodes 8, 18 of the upper and lower arm pn diodes 6, 16, respectively. In addition, the lower arm constant current circuits 10 and 20 may be built in the lower arm gate control circuit 19 in some cases.

Unlike the conventional circuit, the cathode 8 of the upper arm pn diode 6 is connected to the emitter 3 of the upper arm IGBT 1
Do not connect with Therefore, the cathodes 8, 18 of the upper and lower arm pn diodes 6, 16 can be set to a common ground potential.

A constant current flows from the lower arm constant current circuits 10 and 20 to the upper and lower arm pn diodes 6 and 16 which are connected to the lower arm gate control circuit 19. When the upper and lower arm IGBTs 1 and 11 operate and the temperature rises,
The forward voltage drop (ON voltage) of the upper and lower arm pn diodes 6, 16 decreases. The anode of this pn diode
The voltage between the cathodes (ON voltage) is taken out as temperature signals from the upper and lower arm temperature signal terminals 21 and 22 and the temperature signal ground terminal 23 via the lower arm gate control circuit 19.

As described above, since the emitter 3 of the upper arm IGBT 1 and the cathode 8 of the upper arm pn diode 6 are insulated, the emitter 3 of the upper arm pn diode 6 can be connected without a conventionally required level down circuit. Cathode 8
Can be directly connected to the ground GND. Up,
By connecting the cathodes 8, 18 of the lower arm pn diodes 6, 16 to a common ground GND, a temperature signal can be easily taken out to the outside. Further, since the temperature signal does not pass through the level down circuit, the temperature detection speed is high and the temperature signal can be taken out with high accuracy. Further, since a level down circuit and a photocoupler circuit are not required, cost reduction can be achieved.

Incidentally, the temperature signal taken out to the outside is
The IGBT 1 is transmitted to the gate control circuits 9 and 19 via an overheat prevention circuit and a level shift circuit (not shown),
The IGBTs 1 and 11 can be prevented from overheating by turning off the gate of the IGBT 11 or reducing the gate voltage.
In the drawing, VCC-H indicates the high potential side of the power supply for driving the upper arm gate control circuit 9, and VCC-L indicates the high potential side of the power supply for driving the lower arm gate control circuit 19.

Further, the present invention relates to the I
In addition to GBT (main semiconductor element), power MOSFET,
It can be widely applied to power semiconductor elements that generate heat, such as bipolar transistors, thyristors, GTO thyristors, and high-voltage diodes.

FIG. 2 shows a second embodiment of the present invention, showing a cross section of a main part of a semiconductor device with a temperature detecting sensor and a circuit for extracting a temperature signal to the outside. FIG. 2 shows a cross-sectional view of a main part of a portion surrounded by a dotted line 40 and a temperature detection circuit portion when the circuit of FIG. 1 is formed on a semiconductor substrate. Specifically, upper arm IGB
FIG. 2 shows a cross-sectional view of a main part of T1 and an upper arm pn diode 6.
Here, the first conductivity type is shown as n-type and the second conductivity type is shown as p-type, but the conductivity type may be reversed.

A p-well region 42 is formed in a surface layer of an n-semiconductor substrate (the n-semiconductor substrate at the undiffused portion after each diffusion becomes an n ⁻ base region 41).
An n-emitter region 43 is formed in the surface layer of the p-well region 4 between the n-emitter region 43 and the n ⁻ base region 41.
2, a gate oxide film 44 is formed, and a gate electrode 45 is formed on the gate oxide film 44. An emitter electrode 46 is formed on the n emitter region 43. Further, a p collector region 47 is formed on the other surface of the n semiconductor substrate, and a collector electrode 48 is formed on the p collector region 47. The collector electrode 48, the emitter electrode 46, and the gate electrode 45 are connected to the collector terminal C, the emitter terminal E, and the gate terminal G, respectively. Thus, the upper arm IGBT 1 is formed. A p region 51 is formed on the surface layer of the n semiconductor substrate apart from the p well region 42, and a p anode region 53 and an n cathode region 54 are formed on the p region 51 with a thin film of polysilicon or the like via an oxide film 52. An anode electrode 55 and a cathode electrode 56 are formed on these regions to form an upper arm pn diode 6. However, the p region 6 is a p well region 42
It does not matter.

The upper arm pn diode 6 is a temperature detection sensor for the upper arm. The cathode 8 of the upper arm pn diode 6 and the emitter 3 of the upper arm IGBT 1 are not connected. The anode 7 of the upper arm pn diode 6 includes an upper arm constant current circuit 10 and a lower arm gate control circuit 19
To the lower arm gate control circuit 19 and the upper arm temperature signal terminal 21. The emitter electrode 46 of the upper arm IGBT 1 is connected to the emitter terminal E,
Is connected to the collector terminal of the lower arm IGBT, not shown, and also serves as an output point.

Here, since the dielectric breakdown electric field strength of the oxide film 52 is 8 × 10 ⁶ V / cm, in order to prevent the dielectric breakdown of the oxide film, the thickness of the oxide film t (μm) Value V of the potential difference between the semiconductor substrate and the temperature detection sensor
The relationship with _MAX (V) is as follows.

[0035]

T (μm) ≧ V _MAX (V) / 800

If the thickness of the oxide film satisfies this relationship, the dielectric breakdown of the oxide film 52 does not occur, and the cathode 8 of the upper arm pn diode 6 can be connected to the ground GND. When the rated voltage of the semiconductor device is applied to the oxide film, V _MAX is the rated voltage of the IGBT (main semiconductor element).

By forming the upper arm pn diode 6 on the p region 51 via an oxide film 52,
Even at the pn junction between the region 51 and the n ⁻ base region 41, the voltage applied between the emitter E and the ground GND is shared, so that the voltage shared by the oxide film 52 is reduced, and the reliability is improved.

When the thickness t of the oxide film satisfies the above expression, the p region 51 in FIG. 2 may be deleted. However, it is desirable to have the p region 51 from the viewpoint of reliability.

In place of the upper arm pn diode, a thin film resistor made of polysilicon or the like may be formed on the oxide film, and a temperature detecting sensor may be used by utilizing a temperature change of the resistance value.

[0040]

According to the present invention, by forming a temperature detection sensor on a semiconductor substrate on which a main semiconductor element is formed via an oxide film having an optimum thickness, the temperature detection sensor of the upper arm (upper arm pn) is formed. The reference voltage of the temperature signal from the diode can be directly dropped to the ground without going through a level down circuit or a photocoupler circuit, and can be extracted to the outside. As described above, the temperature detection speed is high and the temperature signal can be externally taken out with high accuracy because the temperature signal is not passed through the level down circuit or the photocoupler circuit. In addition, since a level down circuit and a photo coupler circuit become unnecessary,
Cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is an inverter circuit diagram including a circuit for extracting a temperature signal to the outside, including a semiconductor device with a temperature detection sensor according to a first embodiment of the present invention;

FIG. 2 is a diagram showing a cross section of a main part of a semiconductor device with a temperature detection sensor and a circuit for extracting a temperature signal to the outside according to a second embodiment of the present invention;

FIG. 3 is a circuit diagram showing a series arm composed of a power semiconductor element, a load, and a gate control circuit in a normal inverter circuit;

FIG. 4 is an inverter circuit diagram having a conventional temperature detection circuit.

FIG. 5 is an inverter circuit diagram having another conventional temperature detection circuit.

FIG. 6 is a sectional view of a main part when the circuit of FIG. 5 is formed on a semiconductor substrate;

[Explanation of symbols]

Reference Signs List 1 upper arm IGBT 2, 12 collector 3, 13 emitter 4, 14 gate 5, 15 freewheel diode 6 upper arm pn diode 7, 17 anode 8, 18 cathode 9 upper arm gate control circuit 10 upper arm constant current circuit 11 lower arm IGBT 16 Lower arm pn diode 19 Lower arm gate control circuit 20 Lower arm constant current circuit 21 Upper arm temperature signal terminal 22 Lower arm temperature signal terminal 23 Temperature signal ground terminal 24 Load 31 High potential side of main power supply 32 Low potential of main power supply Side 33 Midpoint 40 IGBT with temperature detection sensor 41 n ^- base region 42 p-well region 43 n emitter region 44 gate oxide film 45 gate electrode 46 emitter electrode 47 p collector region 48 collector electrode 51 p region 52 oxide film 53 p anode region 5 n cathode region 55 anode electrode 56 cathode electrode C collector terminals E emitter terminal G gate terminal GND Ground

Claims (8)

[Claims] 1. A semiconductor device, wherein a temperature detection sensor formed on a main surface of a semiconductor substrate is electrically connected to a circuit system having a reference potential different from a reference potential of a circuit system of the semiconductor substrate. 2. The semiconductor device according to claim 1, wherein said temperature detection sensor is formed on said semiconductor substrate via an insulating film. 3. The semiconductor device according to claim 2, wherein said temperature detection sensor is a semiconductor element or a resistor. 4. The semiconductor device according to claim 3, wherein said semiconductor element is a diode. 5. The semiconductor device according to claim 2, wherein said insulating film is an oxide film. 6. The thickness t (μm) of the oxide film is equal to the maximum value V of the potential difference between the semiconductor substrate and the temperature detection sensor.
_6. The semiconductor device according to claim 5, wherein a relationship of _MAX (V) and t ≧ V _MAX / 800 is satisfied. 7. A semiconductor conversion device driven by a main power supply, wherein an upper arm main semiconductor element connected to a high potential side of the main power supply and a lower arm connected to a low potential side of the main power supply. The semiconductor device according to claim 2, wherein, of the arm main semiconductor elements, the substrate includes the upper arm main semiconductor element. 8. The temperature detecting sensor according to claim 1, wherein said temperature detecting sensor is of a first conductivity type.
The semiconductor device according to claim 2, wherein the semiconductor device is formed via an insulating film in a second region of the second conductivity type selectively formed on the region or on a surface layer of the first region.