JPH0318336B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel semiconductor device having a self-overheating protection function.

Transistors or transistors included in integrated circuits have undergone numerous improvements and have made significant progress in terms of ratings and characteristics, but they are susceptible to overheating due to overcurrent and current concentration and require sufficient margin for the rated junction temperature when used. If the device is designed with a temperature sensor, or if overheating is expected to occur due to an unexpected accident, an overheat, overcurrent, or overvoltage protection circuit must be provided with a separate temperature detection element.

In consideration of this point, Japanese Patent Application Laid-Open No. 54-157086 "Semiconductor Device" proposes that a heat-sensitive thyristor coexist within the same substrate on which a transistor is formed to provide overheat protection. However, this device has a problem in that when overheat protection is performed by operating the heat-sensitive thyristor, the transistor stops operating, and the transistor cannot be operated until the heat-sensitive thyristor is stopped from operating by an external circuit.

The present invention has been developed in view of the above-mentioned problem, and uses a self-resetting type temperature sensing element to stop normal operation of the transistor when the temperature of the transistor exceeds a predetermined temperature, and from this point on, the temperature of the transistor drops below the predetermined temperature. Therefore, it is an object of the present invention to provide a semiconductor device that protects the transistor from overheating by restoring normal operation of the transistor and allows the transistor to continue operating even during overheating protection.

The present invention will be described below with reference to embodiments shown in the drawings.

Fig. 1 is an equivalent circuit diagram for explaining the operation of a Darlington transistor with self-overheating protection function showing a first embodiment of the present invention, and Fig. 2 is a schematic cross-sectional diagram of a transistor that realizes the equivalent circuit diagram of Fig. 1. This is an example of a structural diagram. In these figures 1 and 2, 1
is a phosphorus-diffused Darlington transistor.
An n ⁺ type collector layer, 2 is a P type high resistivity P ^- type paste layer formed by vapor phase epitaxial growth on the n ⁺ type collector layer 1, and 5 and 6 are the output side transistors 12 of the Darlington transistor, respectively. For extracting the base electrode of the input side transistor 13
Formed by diffusing boron in a P ⁺ type region. 4 and 9 are the n ⁺ type emitter layer of the output side transistor 12 and the n ⁺ type emitter layer of the input side transistor 13 of the Darlington transistor, both of which are formed by diffusing phosphorus onto the P ^- type base layer 2. . Further, 3 is an n-type isolation layer for electrically isolating the output side, the input side, and the diode 14, and is formed by diffusing phosphorus. 11 is the collector electrode of the Darlington transistor that makes low resistance contact with the n ⁺ type collector layer; 1
1' is the collector terminal, 5a and 6a are the base electrodes of the output side transistor 12 and the input side transistor 13 which are in low resistance contact with the P ⁺ type base electrode layers 5 and 6, respectively, 6a is the base electrode of the Darlington transistor, and 6' is the base Terminals 4a and 9a are emitter electrodes of the output side transistor 12 and input side transistor 13 which are in low resistance contact with the n ⁺ type emitter layers 4 and 9, respectively, and 4' is the emitter terminal. As shown in the figure, the input side transistor 13 and the output side transistor 12 have an emitter electrode 9a and a base electrode 5a electrically connected to form a so-called Darlington connection. A diode 14, which serves as a temperature sensing element whose temperature is detected in the Darlington transistor having such a structure and whose reverse breakdown voltage rapidly decreases at a predetermined temperature, is integrated on the n ⁺ type silicon substrate 1 as shown in the figure.
The diode 14 is obtained by forming an n ⁺ -type region 10 and a P ⁺ -type region 7 for electrode extraction on the P ^- -type base layer 2 . The anode electrode 7a of the diode 14 is the emitter electrode 4a, and the cathode electrode 1 is the emitter electrode 4a.
By connecting 0a to the base electrode 6a, the first
As shown in the figure, a diode 14 inserted in the opposite direction is formed between the base terminal 6' and emitter terminal 4' of the Darlington transistor.

The operation of the Darlington transistor with self-overheating protection function having this configuration will be explained with reference to the equivalent circuit shown in FIG. As is well known, the reverse breakdown voltage of the diode 14 decreases as the temperature increases. When the temperature of the Darlington transistor is low, the reverse breakdown voltage of the diode 14 is sufficient to reduce the base-emitter forward voltage drop V _BED of the Darlington transistor.
taller than. Therefore, even if the diode 14 is connected as shown in Fig. 1, the base current _iB is
Almost no current flows through the transistor, and normal operation as a transistor is performed, and collector current _iC flows. Next, when the power loss of the Darlington transistor increases significantly due to overcurrent or the like and the temperature rises, the reverse breakdown voltage of the diode 14 begins to decrease rapidly. In this example, the diode 14 is 2 mm□, the P ^- type base concentration is 2 × 10 ¹⁴ cm ^-3 , and the temperature (T°C) and the withstand voltage BV _D of the diode 14 at a reverse current of 10 mA are determined.
was as shown in Figure 3. This current value of 10 mA is the base current value when this Darlington transistor is operated normally. On the other hand, as is well known, the base-emitter forward voltage V _BED of a Darlington transistor increases by approximately 4 mV/
Decreases with temperature coefficient of °C. In this example, 10mA
The relationship between V _BED and temperature at the forward current was as shown in Figure 3. As a result, when the temperature rise of the Darlington transistor reaches approximately V _BED BV _D , most of the base current i _B flows to the diode 14, and the base current of the Darlington transistor effectively decreases rapidly. As a result, the collector current decreases, Darlington transistor power dissipation is controlled. At this time, the ratio of the base current flowing through the diode 14 and the Darlington transistor is determined at the point where the temperature due to power loss in the Darlington transistor is a constant temperature that satisfies the above relationship, and this temperature is approximately
The temperature satisfies V _BED BV _D.

FIG. 4 shows the V _CE of the TO-3 can package alone for the Darlington transistor of this embodiment, one without and one with a protection diode 14.
= 10V, collector current 1A is applied, and the application time (t) and TO-3 package temperature (T℃) are measured when heat is generated.The one without protection diode 14 generates heat as shown in A. It was destroyed due to thermal runaway (point X in the figure), but the one with a protection diode was stable at about 200°C as shown in B. The above stable temperature is the allowable junction temperature T _DA of Darlington transistor with overheat protection.
To choose the temperature within the range of V _BED BV _D in Figure 3, T _DA
It should be within the range. This is primarily achieved by controlling BV _D and by varying the effective area of the diode 14 and the impurity concentration of the P ⁺ -P ^- -N ⁺ junction.

The Darlington transistor with self-overheating protection function shown in Figure 2 has the protection diode 14 built into the same silicon board as described above, so the temperature of the Darlington transistor can be detected quickly and overheating caused by short-term overcurrent can be prevented. can also work effectively. Further, in this first embodiment, the protection diode 1
4 can be made together with the Darlington transistor manufacturing process, which has the advantage of reducing the manufacturing effort.

Next, a second embodiment will be explained. FIG. 5 is an equivalent circuit diagram thereof, and FIG. 6 is a schematic cross-sectional structural diagram of a transistor with a self-overheating protection function formed in an integrated circuit that realizes the equivalent circuit of FIG. This fifth
6, the same or corresponding parts as in FIGS. 1 and 2 are denoted by the same reference numerals. The difference in structure from FIG. 1 is that there is no input-side transistor structure because it is not a Darlington transistor type, and the following points.

In place of the diode 14 described in the first embodiment
A P ⁺ emitter layer 19, an n ⁺ base layer 18, and a P ⁺ collector electrode extraction region 17 are formed to form a PNP transistor 16, and an emitter electrode 19a, a base electrode 18a, and a collector electrode 17a are formed to make low resistance contact, respectively. do. Base electrode 18a and emitter electrode 19 of the PNP transistor 16
a and also to the base electrode 5a of the transistor 15. Also, PNP transistor 1
The equivalent circuit shown in FIG. 5 is realized by connecting the collector electrode 17a of No. 6 to the emitter electrode 4a.

Note that the PN junction referred to in the present invention is an n ⁺ type base layer 1
8 and the P ^- type base layer 2.

The operation of the transistor with self-overheating protection function having this configuration has the following characteristics. Since the Darlington transistor described in the first embodiment has an extremely high hFE, the base current required for operation can be used at an extremely small value. Therefore, by utilizing the temperature dependence of the reverse leakage current of the diode 14, self-overheat protection could be easily achieved. However, in order to increase the value of this reverse leakage current, the area of the diode 14 must be increased, which has the disadvantage that it is unsuitable for drawing the base current of, for example, a single transistor used with a large base current. have.
In order to improve this drawback, the leakage current between the base and emitter of the transistor 16 can be amplified by adopting a structure like the transistor 16 shown in FIG. The concentration of P ^- layer is 2 × 10 ¹⁴ cm ^-3 ,
When the transistor 16 of 0.5 mm ² is formed, the V _CE -I _CD characteristic depending on the temperature is as shown in FIG. 7, and a large leakage current I _CD can be obtained. This roughly reduces the base-emitter leakage current of the transistor 16.
This is the result of h _FE multiplied by h _FE . Therefore, even the base current of the transistor 15 used at 100 mA, for example, can be sufficiently drawn into the transistor 16, and the same effect as in the first embodiment can be obtained. Further, the same effect can be obtained even when the base terminal of the transistor 16 shown in FIG. 5 is not connected to the emitter terminal.

Furthermore, in the second embodiment, in order to form the PNP transistor 16, a special process for forming the P ⁺ emitter layer of the PNP transistor must be added. One way to improve this and obtain similar effects without requiring special additional steps is to create a structure in which the lateral NPN transistor 17 is constructed as shown in FIG. FIG. 9 is an equivalent circuit diagram thereof.

In FIG. 8, 20 is a P ⁺ type base layer, 21
is an n ⁺ type emitter layer, 22 is an n ⁺ type collector layer, and the base electrode 20a and the emitter electrode 2 are respectively
1a, and is connected to the collector electrode 22a. still,
The PN junction referred to in the present invention is the n ⁺ type collector layer 22 and
It is formed between the P ^- type base layer 2 and the P-type base layer 2.

The self-overheat protection transistor described above increases the junction temperature detection speed by configuring the diode 14 or the temperature-sensitive transistor 16 on the same substrate, but it is difficult to detect a relatively slow temperature rise. A similar effect can be obtained by arranging a temperature sensing element 31 such as the diode 14 or the temperature sensing transistor 16 on or near the transistor chip 30 as shown in FIG.

In addition, the temperature sensing element is a protected circuit 40 composed of a transistor, as shown in FIGS. 11 and 12.
A similar effect can be obtained by connecting it in parallel with the power supply. In other words, the transistor 41 as a temperature sensing element has a temperature of 13.
The V _CE -I _C characteristic as shown in the figure is obtained, and the circuit drive current is drawn at a predetermined temperature due to the heat from the protected circuit 40, thereby stopping the operation of the circuit at a predetermined temperature or higher. Also, V _CE of this transistor 41
As shown in Fig. 14, when I _C = constant, it has the characteristic of decreasing rapidly as the temperature rises, so even for a circuit driven at a constant voltage as shown in Fig. The operation of the circuit is then stopped.

As described above, the present invention includes a transistor that operates normally within a predetermined temperature of 160°C or higher, is disposed at a position that receives heat conduction from this transistor, and has a PN junction in its configuration.
When a PN junction is electrically connected in parallel between the base electrode and the emitter electrode of the transistor in the forward and reverse directions between the base and emitter of the transistor, and the temperature of the transistor exceeds the predetermined temperature, the PN junction has a characteristic in which the magnitude relationship of the reverse breakdown voltage with respect to the forward voltage between the base and emitter of the transistor is from large to small, and when the temperature of the transistor exceeds the predetermined temperature, the transistor is activated according to the characteristic. and a temperature sensing element that automatically returns to non-operation and returns the transistor to normal operation when the temperature of the transistor drops below the predetermined temperature. It is possible to perform overheat protection by stopping normal operation of the transistor when the temperature exceeds the temperature limit, and with this overheat protection, when the temperature of the transistor decreases, the temperature sensing element is deactivated and the operation of the transistor can be continued. Therefore, even when the transistor continues to generate heat, there is an excellent effect that the temperature of the transistor can be stably maintained around a predetermined temperature by activating or deactivating the temperature sensing element.

[Brief explanation of the drawing]

1, 5, and 9 are equivalent circuit diagrams of each embodiment of the present invention, and FIGS. 2, 6, and 8 are equivalent circuit diagrams of each embodiment of the present invention.
Figures 3 and 4 are schematic cross-sectional structural diagrams of integrated circuits that realize the equivalent circuits of Figures 5 and 9, respectively.
7, 13, and 14 are characteristic diagrams used to explain the operation. FIG. 10 is a perspective view of a temperature-sensitive element mounted on a transistor chip.
FIG. 2 is an electrical wiring diagram showing another embodiment of the present invention. 12, 13...transistor, 14...diode as a temperature sensing element.

Claims (1)

[Scope of Claims] 1. A transistor that operates normally within a predetermined temperature of 160° C. or higher, and is disposed at a position receiving heat conduction from the transistor and has a PN junction in its configuration, and this PN junction The base electrode and the emitter electrode of the transistor are electrically connected in parallel in the forward and reverse directions between the base and emitter of the transistor, and when the temperature of the transistor exceeds the predetermined temperature, the reverse direction of the PN junction The transistor has a characteristic that a magnitude relationship between a breakdown voltage and a forward voltage between the base and emitter of the transistor is from large to small, and operates according to the characteristic to stop the operation of the transistor when the temperature of the transistor exceeds the predetermined temperature. and a temperature sensing element that self-returns to non-operation to return the transistor to normal operation when the temperature of the transistor falls below the predetermined temperature from this point on. 2. The semiconductor device according to claim 1, wherein the transistor and the temperature sensing element are formed on the same semiconductor substrate. 3. The semiconductor device according to claim 1, wherein the temperature sensing element is arranged near the transistor.