JP2009268336A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid interference of a diode element with a gate signal of an IGBT element and prevent an increase in forward loss of a diode in a semiconductor device with a diode built-in IGBT. <P>SOLUTION: A current caused to flow in a main diode element 22a is detected by a current-detecting diode sense element 22b and a sense resistor 30. While a potential difference Vs at both ends of the sense resistor 30 is monitored by a feedback circuit unit 40, whether a current is caused to flow at the diode element 22a is determined based on the potential difference Vs. If it is determined that a current is caused to flow at the diode element 22a, a stop signal, which stops drive of an IGBT element 21a, is entered from the feedback circuit unit 40 into an AND circuit 10, so the drive of the IGBT element 21a is stopped by the AND circuit 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor device including an IGBT element with a built-in diode, and more particularly to an apparatus in which a diode element and an IGBT element are prevented from interfering with each other.

Conventionally, a diode built-in IGBT element in which a diode element and an IGBT element are provided on the same semiconductor substrate has been proposed (see, for example, Patent Document 1). This diode built-in IGBT element has a structure in which the anode electrode of the diode element and the emitter electrode of the IGBT element are used as a common electrode, and the cathode electrode of the diode element and the collector electrode of the IGBT element are used as a common electrode. This diode built-in IGBT element is incorporated in an inverter circuit, for example, and is used for PWM control of a load.
JP-A-6-351226

  However, when the above-mentioned conventional IGBT element with a built-in diode is incorporated in an inverter circuit, the gate signal of the IGBT element is a signal whose phase is inverted to the upper and lower arms in principle. A gate signal is input. That is, the operation of the diode element and the operation of the IGBT element occur simultaneously. More specifically, the operation of the IGBT element indicates that a gate signal is input to the IGBT element.

  As described above, when the operation of the diode element and the operation of the IGBT element occur at the same time, the electrodes are made common as described above. Therefore, when the channel of the IGBT element is turned on, the anode and cathode of the diode element have the same potential. Try to become. This makes it difficult for the body diode to operate in the forward direction due to the gate potential of the IGBT element. As a result, there is a problem that the forward voltage Vf of the diode element increases and the forward loss of the diode element increases.

  As a method of avoiding such a problem in the device structure, for example, as shown in Proceedings of 2004 International Symposium on Power Semiconductor Devices & ICs, pp261-264, a diode dedicated area, that is, a gate is separated from the body diode of the IGBT cell. It is also conceivable to provide a region that does not exist. However, a region that does not operate as an IGBT element, that is, a region that performs only a diode operation increases. For this reason, if the diode exclusive area is provided while maintaining the chip size, the on-voltage of the IGBT element increases. If the on-voltage of the diode element is fixed, the chip size increases.

  On the other hand, in a DC-DC converter or the like, a method for performing synchronous rectification control by incorporating a DMOS element incorporating a diode element into a control circuit as a switching element is well known. When a current flows through the diode element in the diode built-in DMOS element, a forward voltage is generated in the diode element, and a DC loss corresponding to the forward voltage occurs. Therefore, when such synchronous rectification control is performed, a method of detecting the current of the DMOS element using a current transformer is generally used to turn on the gate signal of the freewheeling DMOS element (for example, Japanese Patent Application Laid-Open No. 2004-180386). Publication).

  However, there is a problem that a current transformer is required as a current sensing element, and the circuit scale becomes large. Therefore, as a method for improving this, it is conceivable to employ a method of monitoring the voltage across the switching element (for example, Japanese Patent Application Laid-Open No. 2004-208407). However, this method requires a control IC that has an input terminal that can withstand the power supply voltage when the power supply voltage is high, and the immunity to noise generated during high-voltage switching becomes severe. Design is required. Therefore, there is a problem that the cost of the control IC increases.

  In view of the above points, the present invention provides a semiconductor device including an IGBT element with a built-in diode that prevents an increase in forward loss of the diode by avoiding interference between the operation of the diode element and the operation of the IGBT element. A second object of the present invention is to prevent an increase in the loss of the forward voltage of the diode element by synchronizing the operation of the diode element and the operation of the DMOS element in a semiconductor device including a DMOS element with a built-in diode.

  In order to achieve the above object, according to the present invention, the diode element (22a) and the IGBT element (21a) driven by the drive signal input to the gate are provided on the same semiconductor substrate. The built-in IGBT element (20) and a drive signal input from the outside are passed through and input to the gate of the IGBT element (21a), and a current flowing through the diode element (22a) is detected, and the diode element (22a) When no current is flowing through the diode, the feedback means (10, 30, 40) that permits the passage of the drive signal input from the outside, while stopping the passage of the drive signal when the current is flowing through the diode element (22a). ).

  Thereby, when the electric current is flowing through the diode element (22a), the driving of the IGBT element (21a) can be stopped. That is, when a current flows through the diode element (22a), the gate signal for driving the IGBT element (21a) is not input to the IGBT element (21a). And the operation of the IGBT element (21a) can be avoided.

  Therefore, since the diode element (22a) and the IGBT element (21a) are simultaneously turned on, the diode element (22a) formed on the same semiconductor substrate as the IGBT element (21a) becomes difficult to operate in the forward direction. An increase in the forward voltage of the diode element (22a) can be avoided. Thus, an increase in forward voltage loss of the diode element (22a) can be prevented.

  In the invention according to claim 2, the feedback means (10, 30, 40) includes a sense resistor (30) for detecting a current flowing through the diode element (22a), and the diode element (22a) has a current. Has a first diode current detection threshold value (Vth1) used for determining that the current flows, and the potential difference (Vs) across the sense resistor (30) and the first diode current detection threshold value (Vth1) are In comparison, when the potential difference (Vs) is larger than the first diode current detection threshold (Vth1), the drive signal inputted from the outside is allowed to pass while the potential difference (Vs) is the first diode current detection threshold (Vth1). If smaller, the drive signal is stopped from passing.

  Thus, in order to detect that a current flows through the diode element (22a), a circuit configuration using the sense resistor (30) can be obtained. As a result, the current flowing through the diode element (22a) can be detected using the potential difference between both ends of the sense resistor (30).

  When the current flowing through the diode element (22a) is detected as described above, the diode built-in IGBT element (20) is a diode in which a current proportional to the current flowing through the diode element (22a) flows as in the invention according to claim 3. It has a sense element (22b), and a current flowing through the diode sense element (22b) can flow through the sense resistor (30).

  The invention according to claim 4 further includes a temperature-sensitive diode element (50) that outputs a forward voltage corresponding to the temperature of heat generated by the operation of the IGBT element with built-in diode (20). The means (10, 30, 40) has a second diode current detection threshold value (Vth1 ′) larger than the first diode current detection threshold value (Vth1), and the temperature sensitivity input from the temperature sensitive diode element (50). When the forward voltage of the diode element (50) exceeds the temperature threshold indicating the high temperature state of the diode built-in IGBT element (20), the potential difference (Vs) across the sense resistor (30) and the second diode current detection threshold (Vth1 ′) ) And are characterized by comparison.

  According to this, when the diode built-in IGBT element (20) is in a high temperature state, it is determined that the current flows through the diode element (22a) even if the current flowing through the diode element (22a) is very small. Can do. Accordingly, when the diode-embedded IGBT element (20) is in a high temperature state and a small current flows through the diode element (22a), the driving of the IGBT element (21a) can be stopped, and thus the diode-embedded IGBT element (20 ) Can be prevented from being destroyed by high temperatures.

  In the invention according to claim 5, the feedback means (10, 30, 40) detects the current flowing through the IGBT element (21a), and when the excess current does not flow through the IGBT element (21a), it is input from the outside. On the other hand, when an excessive current flows through the IGBT element (21a), the passage of the drive signal is stopped.

  As described above, even when an excessive current flows through the IGBT element (21a), the driving of the IGBT element (21a) can be stopped, and the element destruction of the IGBT element (21a) can be prevented.

  In the invention described in claim 6, the feedback means (10, 30, 40) has an overcurrent detection threshold value (Vth2) used for determining that an excessive current is flowing in the IGBT element (21a). If the potential difference (Vs) between both ends of the sense resistor (30) is compared with the overcurrent detection threshold value (Vth2), and the potential difference (Vs) is smaller than the overcurrent detection threshold value (Vth2), the drive input from the outside While the passage of the signal is permitted, when the potential difference (Vs) is larger than the overcurrent detection threshold (Vth2), the passage of the drive signal is stopped.

  Thus, like the diode element (22a), the current flowing through the IGBT element (21a) can be detected using the potential difference between both ends of the sense resistor (30).

  As in the invention described in claim 7, the diode built-in IGBT element (20) includes an IGBT sense element (21b) through which a current proportional to a current flowing through the IGBT element (21a) flows, and the IGBT sense element (21b) includes The flowing current can flow to the sense resistor (30).

  In the invention according to claim 8, the diode built-in DMOS element (100) in which the diode element (121) and the DMOS element (111) driven by the drive signal input to the gate are provided on the same semiconductor substrate; When the current flowing through the diode element (121) is detected and no current flows through the diode element (121), the driving of the DMOS element (111) is stopped while the current flows through the diode element (121) in the forward direction. A feedback means (200) for driving the DMOS element (111) to flow a current in the same direction as a forward current to the diode element (121) to the DMOS element (111). Features.

  As a result, when a forward current flows through the diode element (121), it can flow through the DMOS element (111). Therefore, it is possible to prevent an increase in DC loss corresponding to the forward voltage Vf that occurs when a forward current flows through the diode element (121).

  In the invention described in claim 9, the feedback means (200) includes a sense resistor (30) for detecting a current flowing through the diode element (121), and the current is flowing through the diode element (121). It has a first diode current detection threshold (Vth1) used for determination, compares the potential difference (Vs) across the sense resistor (30) with the first diode current detection threshold (Vth1), and compares the potential difference (Vs1). ) Is larger than the first diode current detection threshold (Vth1), the driving of the DMOS element (111) is stopped, and when the potential difference (Vs) is smaller than the first diode current detection threshold (Vth1), the DMOS element (111) ) Is driven.

  As described above, it is possible to detect that a current flows through the diode element (121) using the potential difference (Vs) generated between both ends of the sense resistor (30).

  As in the invention described in claim 10, the diode built-in DMOS element (100) includes a diode sense element (122) through which a current proportional to a current flowing through the diode element (121) flows, and the diode sense element (122). By causing the current flowing through the sense resistor (30) to flow, a potential difference (Vs) can be generated in the sense resistor (30).

  The invention according to claim 11 is provided with a temperature sensitive diode element (50) for outputting a forward voltage corresponding to the temperature of heat generated by the operation of the diode built-in DMOS element (100), and feedback means ( 200) has a second diode current detection threshold value (Vth1 ′) larger than the first diode current detection threshold value (Vth1), and the temperature-sensitive diode element (50) input from the temperature-sensitive diode element (50). When the forward voltage exceeds the temperature threshold indicating the high temperature state of the diode built-in DMOS device (100), the potential difference (Vs) across the sense resistor (30) is compared with the second diode current detection threshold (Vth1 ′). It is characterized by becoming.

  Thereby, it is possible to easily detect the current flowing through the diode element (121) during a high-temperature operation in which the DC loss of the diode element (121) becomes a problem. Therefore, even when a small current flows through the diode element (121), the DMOS element (111) can be turned on to allow a current to flow through the DMOS element (111), thereby preventing an increase in DC loss of the diode element (121). However, the heat generation of the diode element (121) can be further suppressed.

  In the invention described in claim 12, the feedback means (200) has a third diode current detection threshold value (Vth1 '') larger than the first diode current detection threshold value (Vth1), and the potential difference (Vs). When the value changes to the negative side, the first diode current detection threshold value (Vth1) is compared with the potential difference (Vs) to determine whether to drive the DMOS element (111), while the value of the potential difference (Vs) is determined. Is changed to the positive side, the third diode current detection threshold value (Vth1 ″) is compared with the potential difference (Vs) to determine whether or not to drive the DMOS element (111). Features.

  Accordingly, even if the potential difference (Vs) vibrates due to noise in the vicinity of the first diode current detection threshold (Vth1) or the third diode current detection threshold (Vth1 ″), the DMOS element (111) is turned on / off due to the noise. Can be prevented from switching. Therefore, the noise tolerance of the semiconductor device can be improved.

  In the invention described in claim 13, the feedback means (200) includes a sense resistor (30) for detecting a current flowing through the diode element (121), and current is flowing through the diode element (121). A first diode current detection threshold value used for determination and corresponding to a potential difference (Vs) across the sense resistor (30) when the drain current flowing through the DMOS element (111) is the first drain current value (Id1) (Vth1) corresponds to a potential difference (Vs) when the drain current is a second drain current value (Id2) larger than the first drain current value (Id1) and is larger than the first diode current detection threshold (Vth1). The first diode has a large second diode current detection threshold (Vth1 ″) and the potential difference (Vs) changes to the negative side. The current detection threshold value (Vth1) is compared with the potential difference (Vs), and when the potential difference (Vs) is larger than the first diode current detection threshold value (Vth1), the gate driving of the DMOS element (111) is stopped. When the potential difference (Vs) is smaller than the first diode current detection threshold (Vth1), the DMOS element (111) is gate-driven, and when the value of the potential difference (Vs) changes to the positive side, the second diode current detection threshold (Vth1) '') And the potential difference (Vs) are compared. When the potential difference (Vs) is larger than the second diode current detection threshold (Vth1 ″), the gate drive of the DMOS element (111) is stopped while the potential difference (Vs) When D is smaller than the second diode current detection threshold value (Vth1 ″), the DMOS element (111) is left gate-driven. And features.

  According to this, regarding the determination threshold value for turning on / off the gate of the DMOS element (111), the second drain current value (Id2) is larger than the first drain current value (Id1), and the second diode current detection threshold value is set. (Vth1 ″) is larger than the first diode current detection threshold (Vth1). That is, even if the value of the potential difference (Vs) after turning on the gate of the DMOS element (111) increases, the potential difference (Vs) does not increase so as to exceed the second diode current detection threshold (Vth1 ″). The gate will never turn off again. Therefore, oscillation in which the gate of the DMOS element (111) is repeatedly turned on / off can be prevented.

  In the invention according to claim 14, the diode built-in DMOS element (100) includes a diode sense element (122) through which a current proportional to a current flowing through the diode element (121) flows, and the diode sense element (122) includes A characteristic is that a potential difference (Vs) is generated in the sense resistor (30) when the flowing current flows in the sense resistor (30).

  Thus, by using the diode sense element (122), a potential difference (Vs) can be generated in the sense resistor (30).

  The invention according to claim 15 includes a temperature-sensitive diode element (50) for outputting a forward voltage corresponding to the temperature of heat generated by the operation of the diode built-in DMOS element (100), and feedback means ( 200) with respect to the temperature of the element converted from the forward voltage of the temperature-sensitive diode element (50), the first and second diode current detection thresholds (Vth1, Vth1 ″) with the temperature change of the element. The temperature correction map has a value that changes. When comparing the first and second diode current detection threshold values (Vth1, Vth1 ″) and the potential difference (Vs), the first and second values are used using the temperature correction map. The comparison is performed by correcting the diode current detection threshold values (Vth1, Vth1 ″) to values corresponding to the temperature change of the element.

  As described above, by performing temperature correction of the first and second diode current detection threshold values (Vth1, Vth1 ″), synchronous rectification can always be performed with a constant current.

  In the invention described in claim 16, a driving signal for driving the DMOS element (111) is inputted from the feedback means (200), and a switching signal for driving the DMOS element (111) is inputted from the outside. When the switching signal is inputted without the driving signal being inputted, the driving means (400) which causes the DMOS element (111) to function as the switching element by driving the DMOS element (111) according to the switching signal. ).

  Thereby, a semiconductor device having both a rectifying function by the diode element (121) and a switching function by the DMOS element (111) can be provided.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The semiconductor device shown in the present embodiment is used as, for example, a power switching element (hereinafter referred to as a diode built-in IGBT element) used in an EHV inverter module.

  FIG. 1 is a circuit diagram of the semiconductor device according to the present embodiment. As shown in this figure, the semiconductor device includes an AND circuit 10, a diode built-in IGBT element 20, a sense resistor 30, and a feedback circuit 40.

  The AND circuit 10 is a logic circuit that outputs a Hi level signal when all input signals are at the Hi level, and is a so-called AND circuit. The AND circuit 10 receives an external PWM gate signal for driving the diode built-in IGBT element 20 and the output of the feedback circuit 40. The PWM gate signal is generated by an external PWM signal generation circuit or the like and is input to the input terminal of the AND circuit 10. The PWM gate signal corresponds to the drive signal of the present invention.

  The diode built-in IGBT element 20 includes an IGBT part 21 and a diode part 22. Such a diode built-in IGBT element 20 has an IGBT portion 21 and a diode portion 22 formed on the same semiconductor substrate.

  The IGBT unit 21 includes a main IGBT element 21a connected to a load or the like, and a current detection IGBT sense element 21b used for detecting a current flowing through the main IGBT element 21a. The IGBT element 21a and the IGBT sense element 21b are formed in the same structure. A current proportional to the current flowing through the IGBT element 21a flows through the IGBT sense element 21b. The IGBT element 21a and the IGBT sense element 21b are configured by, for example, a trench gate structure, and the gates are shared.

As the IGBT element 21a and the IGBT sense element 21b, for example, a P-type base region for setting a channel region is formed in the surface layer portion of the N− type drift layer, and an N + type source region is formed in the surface layer portion of the P-type base region. A trench is formed so as to penetrate the N + type source region and the P type base region to reach the N − type drift layer, and further, a gate insulating film made of SiO ₂ and PolySi are formed on the inner wall of the trench It is possible to employ a structure in which a trench gate structure including a trench, a gate insulating film, and a gate electrode is formed.

  The gate voltage control in the main IGBT element 21a and the current detection IGBT sense element 21b is performed by the PWM gate signal that has passed through the AND circuit 10. That is, for example, if the PWM gate signal permitted to pass through the AND circuit 10 is a Hi level signal, the IGBT element 21a can be turned on and driven. If the PWM gate signal is a Low level signal, the IGBT element can be driven. The drive can be stopped by turning off 21a. On the other hand, when the PWM gate signal is stopped from passing through the AND circuit 10, the IGBT element 21a and the IGBT sense element 21b are not driven.

  In addition, a load or a power source (not shown) is connected to the collector of the IGBT element 21a, and a main current flows between the collector and emitter of the IGBT element 21a. The collector of the IGBT sense element 21b on the current detection cell side is shared with the collector of the IGBT element 21a on the main cell side, and the emitter of the IGBT sense element 21b on the current detection cell side is connected to one end of the sense resistor 30. Yes. The other end of the sense resistor 30 is connected to the emitter of the IGBT element 21a. As a result, a sense current for current detection flowing from the emitter of the IGBT sense element 21b on the current detection cell side, that is, a current proportional to the current flowing through the main IGBT element 21a flows through the sense resistor 30, and The potential difference Vs is fed back to the feedback circuit 40.

  The diode portion 22 is for commutating the load current flowing through the IGBT element 21a, and for detecting the main diode element 22a connected to the IGBT element 21a and the current flowing through the main diode element 22a. And a diode sensing element 22b for current detection used. The cathodes of the main diode element 22a and the current detection diode sense element 22b are shared.

  In the diode portion 22, the anode of the diode element 22 a is connected to the emitter of the IGBT element 21 a, and the anode of the diode sense element 22 b is connected to one end of the sense resistor 30. The cathodes of the diode element 22a and the diode sense element 22b are connected to the collector of the IGBT element 21a.

  As the diode element 22a and the diode sense element 22b, for example, a number of trench gate structures similar to the IGBT part 21 are formed in the surface layer part of the semiconductor substrate, and an N + type region is provided on the back surface of the N-type silicon substrate. The structure can be adopted. In such a configuration, the P-type base region and the N − -type drift layer constituting the IGBT portion 21 can function as a PN diode.

  The feedback circuit 40 determines whether or not a current is flowing through the diode element 22a and whether or not an excessive current is flowing through the IGBT element 21a, and permits the passage of the PWM gate signal input to the AND circuit 10 according to the determination result. Or stop it. For this reason, the feedback circuit 40 uses the diode current detection threshold Vth1 used to determine that current is flowing in the diode element 22a, and the overcurrent used to determine that excess current is flowing in the IGBT element 21a. And a detection threshold value Vth2. In the present embodiment, the diode current detection threshold Vth1 and the overcurrent detection threshold Vth2 are voltage values.

  When the IGBT element 21a is normally driven, that is, when no current flows through the diode element 22a, a current flows from the IGBT sense element 21b to the sense resistor 30. For this reason, when the potential of the emitter of the IGBT element 21a is used as a reference, the potential difference Vs between both ends of the sense resistor 30 becomes a positive value. Conversely, when a current flows through the diode element 22a, a current flows from the sense resistor 30 to the diode sense element 22b. For this reason, the potential difference Vs across the sense resistor 30 is negative when the emitter of the IGBT element 21a is used as a reference. Therefore, in order to detect that a current flows through the diode element 22a, the diode current detection threshold value Vth1 is set to a negative value.

  On the other hand, when the IGBT element 21a is normally driven, the potential difference Vs across the sense resistor 30 becomes a positive value as described above. However, when an excess current flows through the IGBT element 21a, the value of the sense current flowing from the IGBT sense element 21b to the sense resistor 30 becomes large, so the overcurrent detection threshold Vth2 is set to a positive value.

  Such a feedback circuit 40, when driving the IGBT element 21a, outputs an output that allows passage of the PWM gate signal input to the AND circuit 10, while inputting the potential difference Vs between both ends of the sense resistor 30, and the potential difference. When Vs is smaller than the diode current detection threshold Vth1 or larger than the overcurrent detection threshold Vth2, an output for stopping the passage of the PWM gate signal input to the AND circuit 10 is output. The feedback circuit 40 is configured by combining circuits such as operational amplifiers. The above is the overall configuration of the semiconductor device according to the present embodiment.

  The AND circuit 10, the sense resistor 30, and the feedback circuit 40 described above correspond to feedback means of the present invention.

  Next, the operation of the semiconductor device will be described with reference to FIG. FIG. 2 is a diagram showing the relationship between the potential difference Vs across the sense resistor 30, the diode current detection threshold Vth1, the overcurrent detection threshold Vth2, and the output of the feedback circuit 40. First, the normal operation of the semiconductor device will be described.

  A PWM gate signal is generated as a drive signal for driving the IGBT element 21 a of the semiconductor device by an external circuit such as a PWM signal generation circuit and is input to the AND circuit 10. On the other hand, the diode element 22a is off and no current flows through the diode sense element 22b. For this reason, the potential on one end side connected to the IGBT sense element 21b in the sense resistor 30 is higher than the other end side connected to the emitter of the IGBT element 21a, and the sense resistor 30 with the emitter of the IGBT element 21a as a reference. The potential difference Vs at both ends of the positive value is a positive value.

  Therefore, as shown in FIG. 2, since the potential difference Vs is larger than the negative diode current detection threshold Vth1, the feedback circuit 40 determines that no current flows through the diode element 22a. As a result, the output of the feedback circuit 40 is set to the Hi level as shown in FIG. 2 and is input to the AND circuit 10. When the high-level PWM gate signal and the output of the feedback circuit 40 are input to the AND circuit 10, the PWM gate signal is allowed to pass through the AND circuit 10 and input to the IGBT unit 21, and the IGBT unit 21 is turned on. . In this way, the IGBT element 21a is driven, and a current flows through a load (not shown) connected to the collector or emitter of the IGBT element 21a.

  When a current flows through the diode element 22a, the other end of the sense resistor 30 connected to the emitter of the IGBT element 21a has a higher potential than the one end connected to the emitter of the IGBT sense element 21b, and thus the emitter of the IGBT element 21a. The potential difference Vs across the sense resistor 30 with reference to is negative.

  For this reason, when the potential difference Vs becomes smaller than the diode current detection threshold Vth1, it is determined by the feedback circuit 40 that a current is flowing through the diode element 22a. As a result, the output of the feedback circuit 40 is an output that stops the passage of the PWM gate signal input to the AND circuit 10 and is input to the AND circuit 10.

  Therefore, since the signal for driving the IGBT unit 21 is not input from the AND circuit 10, the driving of the IGBT element 21a is stopped. That is, the IGBT element 21a does not operate during the forward operation of the diode element 22a.

  According to this, since the IGBT element 21a and the diode element 22a are formed on the same semiconductor substrate, the channel of the IGBT element 21a is turned on when the diode element 22a operates in the forward direction, so that the anode of the diode element 22a And the cathode do not tend to be at the same potential, and the gate potential of the IGBT element 21a does not make the diode element 22a difficult to operate in the forward direction. That is, the operation of the diode element 22a and the operation of the IGBT element 21a, more specifically, interference between the diode element 22a and the gate signal of the IGBT element 21a can be avoided. As a result, an increase in the forward voltage of the diode element 22a can be avoided, and an increase in the forward voltage loss of the diode element 22a can be prevented.

  On the other hand, when an excess current flows through the IGBT element 21a, the sense current flowing from the IGBT sense element 21b to the sense resistor 30 also increases in proportion to the excess current. The potential difference Vs is higher than the potential difference Vs when a current flows through the IGBT element 21a when the IGBT element 21a operates normally.

  Therefore, when the potential difference Vs becomes larger than the overcurrent detection threshold Vth2, it is determined by the feedback circuit 40 that excess current is flowing in the IGBT element 21a. Thereby, similarly to the above, the passage of the PWM gate signal input to the AND circuit 10 is stopped by the output of the feedback circuit 40, and the driving of the IGBT element 21a is stopped. In this way, it is possible to prevent the IGBT element 21a from being destroyed by the excessive current flowing through the IGBT element 21a.

  As described above, in this embodiment, the diode current detection threshold Vth1 and the overcurrent detection threshold Vth2 are provided. Thus, when the potential difference Vs across the sense resistor 30 with respect to the emitter of the IGBT element 21a is equal to or higher than the diode current detection threshold Vth1 and equal to or lower than the overcurrent detection threshold Vth2, the output of the feedback circuit 40 is the AND circuit 10 The output permits the passage of the PWM gate signal input to.

  As described above, the present embodiment is characterized in that the current flowing through the diode element 22a is sensed by the diode sense element 22b and the sense resistor 30. That is, by monitoring the potential difference Vs between both ends of the sense resistor 30 connected to the IGBT sense element 21b, it is determined whether a current is flowing through the diode element 22a, and according to the determination result, the output of the feedback circuit 40 determines the AND. The PWM gate signal input to the circuit 10 is permitted or stopped to pass.

  According to this, when a current flows through the diode element 22a, the driving of the IGBT element 21a is stopped, that is, the passage of the PWM gate signal input to the AND circuit 10 is stopped, and the operation of the IGBT element 21a is stopped. For this reason, it is possible to prevent the operation of the IGBT element 21a and the operation of the diode element 22a from interfering with each other. Thereby, it is possible to prevent an increase in the forward voltage Vf of the diode element 22a caused by the operation of the IGBT element 21a when the diode element 22a is operated. As a result, the forward loss due to the increase of the forward voltage Vf of the diode element 22a can be prevented. Can be prevented from increasing.

  Further, the feedback circuit 40 determines whether an excess current is flowing through the IGBT element 21a by sensing a current flowing through the sense resistor 30. When the feedback circuit 40 determines that an excessive current is flowing in the IGBT element 21a, the driving of the IGBT element 21a can be stopped. Thereby, destruction of the IGBT element 21a can be prevented.

  Furthermore, by configuring a semiconductor device employing the AND circuit 10, the sense resistor 30, and the feedback circuit 40, it is not necessary to change the element structure of the diode-embedded IGBT element 20, and it is not necessary to increase the chip size.

(Second Embodiment)
In the present embodiment, only different parts from the first embodiment will be described. The present embodiment is characterized in that the temperature of the semiconductor device is detected and the diode current detection threshold Vth1 is changed according to the temperature detection.

  FIG. 3 is a circuit diagram of the semiconductor device according to the present embodiment. As shown in this figure, the semiconductor device according to the present embodiment has a configuration in which a temperature sensitive diode element 50 is provided in the configuration shown in FIG.

  The temperature sensitive diode element 50 is used to measure the temperature of the semiconductor device, more specifically, the temperature of the diode built-in IGBT element 20. The temperature-sensitive diode element 50 outputs a voltage corresponding to the temperature, that is, the value of the forward voltage changes, and the forward voltage according to the heat generated by the operation of the diode built-in IGBT element 20. Is output.

  Such a temperature sensitive diode element 50 is configured, for example, by forming polycrystalline Si as an N-type layer and a P-type layer on an insulating film formed on a semiconductor substrate. As shown in FIG. 3, in the present embodiment, four temperature sensitive diode elements 50 are connected in series, and the total forward voltage Vm of the temperature sensitive diode element 50 with respect to the ground is input to the feedback circuit 40. It has become.

  A constant current flows from the feedback circuit 40 to the temperature sensitive diode element 50. Then, as described above, the forward voltage Vm of the temperature-sensitive diode element 50 changed according to the temperature is input to the feedback circuit 40.

  In the present embodiment, the feedback circuit 40 has two diode current detection thresholds Vth1 and Vth1 '. Hereinafter, Vth1 is defined as a first diode current detection threshold, and Vth1 'is defined as a second diode current detection threshold. The second diode current detection threshold value Vth1 'is larger than the first diode current detection threshold value Vth1.

  Further, when the feedback circuit 40 determines that the forward voltage Vm input from the temperature-sensitive diode element 50 exceeds the temperature threshold value indicating the high temperature state of the diode-incorporated IGBT element 20, the feedback circuit 40 is not the first diode current detection threshold value Vth1 but the first voltage detection value Vth1. The two-diode current detection threshold Vth1 ′ is compared with the potential difference Vs across the sense resistor 30.

  That is, when the diode built-in IGBT element 20 is in a high temperature state, the feedback circuit 40 makes it easy to determine that the current is flowing through the diode element 22a even if the current flowing through the diode element 22a is very small. Thereby, the feedback circuit 40 stops the driving of the IGBT element 21a even when a minute current flows through the diode element 22a, and suppresses the heat generation of the IGBT element 20 with a built-in diode.

  Next, the operation of the semiconductor device when the diode built-in IGBT element 20 is in a high temperature state will be described with reference to FIG. FIG. 4 is a diagram showing the relationship between the potential difference Vs across the sense resistor 30, the first diode current detection threshold Vth1, the second diode current detection threshold Vth1 ′, the overcurrent detection threshold Vth2, and the output of the feedback circuit 40. .

  Similarly to the first embodiment, when the PWM gate signal and the output of the feedback circuit 40 are input to the AND circuit 10, the passage of the PWM gate signal input to the AND circuit 10 is permitted, and the IGBT element 21a is driven. Is done. In this case, the forward voltage Vm corresponding to the temperature of the diode built-in IGBT element 20 is detected by the temperature-sensitive diode element 50, and the forward voltage Vm is input to the feedback circuit 40.

  Further, in the feedback circuit 40, when it is determined that the forward voltage Vm input from the temperature-sensitive diode element 50 exceeds the temperature threshold, the first diode current detection threshold Vth1 is set to the second diode current as shown in FIG. The detection threshold value is changed to Vth1 ′.

  Accordingly, it can be determined that the current is flowing through the diode element 22a even when the sense current flowing through the sense resistor 30 is smaller than when the potential difference Vs is compared with the first diode current detection threshold Vth1.

  When the potential difference Vs between both ends of the sense resistor 30 becomes smaller than the second diode current detection threshold Vth1 ′, it is determined by the feedback circuit 40 that a current is flowing through the diode element 22a, and the same as in the first embodiment. Then, the driving of the IGBT element 21a is stopped.

  As described above, when the diode built-in IGBT element 20 becomes high temperature, it is easy to determine whether or not the current is flowing through the diode element 22a by changing the determination criterion of the presence or absence of the current flowing through the diode element 22a. be able to. Thereby, even if the current flowing through the diode element 22a is a value in the small current region, potential interference between the gate signal of the IGBT element 21a and the diode element 22a can be prevented, and the driving of the IGBT element 21a is stopped. Thus, the heat generation of the diode built-in IGBT element 20 can be suppressed.

(Third embodiment)
In the present embodiment, only different parts from the second embodiment will be described. In the second embodiment, each component is configured as a separate part, but this embodiment is characterized in that each component shown in the second embodiment is built in one chip.

  FIG. 5A is an overall schematic diagram of the semiconductor chip 60 according to the present embodiment. FIG. 5B is a circuit diagram of a circuit provided in the semiconductor chip 60, which is the same as the circuit diagram shown in FIG. As shown in FIG. 5A, the semiconductor chip 60 includes a diode built-in IGBT element 20, a temperature sensitive diode element 50, a processing circuit unit 70, a current sensing element 61, a gate pad 62, and a guard ring 63. And.

  The processing circuit unit 70 shown in FIG. 5A includes the feedback circuit 40, the AND circuit 10, and the sense resistor 30 shown in FIG. The feedback circuit 40 is configured by, for example, a thin film transistor circuit.

  The current sense element 61 senses a current flowing through the IGBT element 21a and the diode element 22a, and includes the diode sense element 22b and the IGBT sense element 21b. In the present embodiment, the diode built-in IGBT element 20 is not provided with the diode sense element 22b, and the current flowing through the diode element 21a is detected by the current sense element 61. In the present embodiment, the current sense element 61 is configured to be used for sensing both the IGBT element 21a and the diode element 22a. “Combined” means that both the current flowing through the diode element 22a and the current flowing through the IGBT element 21a can be detected.

  The temperature sensitive diode element 50 is disposed, for example, at the center of the semiconductor chip 60. It is known that the heat generated by the operation of the semiconductor chip 60 is the highest when the heat is concentrated on the central portion of the semiconductor chip 60, so that the temperature-sensitive diode element 50 is disposed at the central portion of the semiconductor chip 60. The

  The gate pad 62 is connected to the input terminal of the AND circuit 10 and is an electrode to which a PWM gate signal is input from the outside.

  A guard ring 63 surrounding the diode built-in IGBT element 20, the temperature sensitive diode element 50, the processing circuit unit 70, the current sensing element 61, and the gate pad 62 is provided at the outer edge of the semiconductor chip 60. The guard ring 63 plays a role of ensuring the breakdown voltage of the semiconductor chip 60.

  As described above, by incorporating the semiconductor device in the semiconductor chip 60, a general-purpose circuit can be used as a PWM control circuit for driving the IGBT unit 21.

(Fourth embodiment)
In the present embodiment, only different portions from the above embodiments will be described. FIG. 6A is an overall schematic diagram of the semiconductor chip 60 according to the present embodiment. FIG. 6B is a view showing the back surface structure of the semiconductor chip 60 shown in FIG. Note that the semiconductor chip 60 shown in FIG. 6A is provided with the semiconductor device shown in the circuit diagram of FIG. 5B as in the third embodiment.

  As shown in FIG. 6A, in the present embodiment, unlike the third embodiment, the diode sense element 22b and the IGBT sense element 21b are separately provided on the semiconductor chip 60, respectively.

  As shown in FIG. 6B, the semiconductor chip 60 is formed on the N-type substrate 80, and the P + type region 81 and the diode part 22 constituting the IGBT part 21 are formed on the back surface of the semiconductor chip 60. N + -type regions 82 constituting the structure are alternately and repeatedly arranged.

  Usually, since the IGBT back surface of the IGBT sense element 21b is only the P + type region 81, the current of the IGBT sense element 21b flows, but the current of the diode sense element 22b hardly flows. However, in this embodiment, since the N + type region 82 is arranged together with the P + type region 81 on the back surface of the chip (double-sided alignment), the output of the diode sense element 22b can be increased, and thus the current detection sensitivity can be increased. it can.

(Fifth embodiment)
In the present embodiment, only portions different from the first to fourth embodiments will be described. In the first to fourth embodiments, the diode built-in IGBT element 20 is employed as the switching element. However, the present embodiment is characterized in that a DMOS element is employed.

  That is, the polarity of the current flowing in the diode element is sensed using the sense element built in the DMOS element so that the diode operation is performed by the DMOS element operation, and the gate signal of the DMOS element is turned on for the time during which the diode element operates in the forward direction. As a result, a current having the same direction as that of the current flowing through the diode element is caused to flow through the DMOS element, so that no current flows through the diode element where the forward voltage is generated, thereby preventing an increase in DC loss of the diode element. Is a feature.

  FIG. 7 is a circuit diagram of the semiconductor device according to the present embodiment. As shown in this figure, the semiconductor device includes a diode built-in DMOS element 100, a sense resistor 30, and a feedback circuit 200. The connection form of the diode built-in DMOS element 100 and the sense resistor 30 is the same as that shown in FIG.

  The diode built-in DMOS device 100 includes a DMOS portion 110 and a diode portion 120. In such a diode built-in DMOS device 100, the DMOS portion 110 and the diode portion 120 are formed on the same semiconductor substrate.

  The DMOS unit 110 includes a main DMOS element 111 connected to a load or the like, and a current detection DMOS sense element 112 used to detect a current flowing through the main DMOS element 111. These DMOS element 111 and DMOS sense element 112 are formed in the same structure. A current proportional to the current flowing through the DMOS element 111 flows through the DMOS sense element 112. The feedback circuit 200 controls the gate voltage in the main DMOS element 111 and the current detection DMOS sense element 112.

  The diode section 120 includes a main diode element 121 connected to the DMOS element 111 and a current detection diode sense element 122 used for detecting a current flowing through the main diode element 121.

  The feedback circuit 200 inputs a potential difference Vs generated at both ends of the sense resistor 30 when a current flows through the main DMOS element 111, and determines whether or not a current flows through the diode element 121 based on the potential difference Vs. The driving of the DMOS element 111 is controlled according to the determination result. Therefore, the feedback circuit 200 has a diode current detection threshold value Vth1 that is used to determine that a current is flowing through the diode element 121. The diode current detection threshold Vth1 is, for example, a voltage value. Here, as in the first embodiment, the diode current detection threshold Vth1 is set to a negative value in order to detect that a current flows through the diode element 121. The feedback circuit 200 operates when a voltage is applied from the power supply 300. The feedback circuit 200 and the sense resistor 30 correspond to the feedback means in the claims.

  Next, the operation of the semiconductor device will be described with reference to FIG. FIG. 8 is a diagram showing the relationship between the potential difference Vs across the sense resistor 30, the diode current detection threshold Vth1, and the output of the feedback circuit 200.

  First, at the timing when the diode element 121 operates by synchronous rectification, a current flows through the diode element 121 in the forward direction, that is, from the anode to the cathode of the diode element 121. As a result, a current also flows through the diode sense element 122 and a potential is generated in the sense resistor 30 connected to the diode sense element 122.

  That is, when a forward current flows through the diode element 121, the other end of the sense resistor 30 connected to the source of the DMOS element 111 has a higher potential than the one end connected to the source of the DMOS sense element 112. The potential difference Vs across the sense resistor 30 with respect to the source of the element 111 is a negative value. The negative potential difference Vs is input to the feedback circuit 200, and the negative potential difference Vs is compared with the negative diode current detection threshold Vth1. If the potential difference Vs is a negative value larger than the diode current detection threshold Vth1, the feedback circuit 200 generates a gate signal (Hi) for turning on the DMOS element 111, as shown in FIG. Element 111 is turned on.

  According to this, when a current is passed through the diode element 121, a forward voltage Vf is required, which causes a DC loss in a circuit in which a semiconductor device is incorporated, but if the DMOS element 111 is turned on, the DMOS element 111 is wired ( Therefore, the current flows from the source to the drain of the DMOS element 111, not to the diode element 121. In other words, the feedback circuit 200 turns on the DMOS element 111 to flow a current in the same direction as the direction in which the forward current flows in the diode element 121 to the DMOS element 111. In this way, the current flowing in the forward direction in the diode element 121 flows in the DMOS element 111, and an increase in the loss of the forward voltage Vf necessary for flowing the forward current in the diode element 121 is prevented. Yes.

  On the other hand, at the timing when a rectifying action is applied to the diode element 121 and a reverse current flows through the diode element 121, the potential on one end side of the sense resistor 30 connected to the DMOS sense element 112 is connected to the source of the DMOS element 111. The potential difference Vs across the sense resistor 30 with respect to the source of the DMOS element 111 becomes a positive value. When the feedback circuit 200 determines that the positive potential difference Vs is larger than the negative diode current detection threshold Vth1, the gate signal (Low) for turning off the DMOS element 111 is shown in FIG. Is generated, and the DMOS element 111 is turned off by the feedback circuit 200. Thus, when the rectifying action is applied to the diode element 121, the DMOS element 111 is turned off.

  As described above, in this embodiment, in the semiconductor device using the diode built-in DMOS element 100, when a forward current flows through the diode element 121, the DMOS element 111 is turned on and a current flows through the DMOS element 111. It is characterized by. Thereby, it is possible to prevent the loss of the forward voltage Vf generated in the diode element 121 when the forward current flows through the diode element 121, and to perform a low-loss SW operation.

(Sixth embodiment)
In the present embodiment, the temperature of the semiconductor device is detected in the circuit of FIG. 7 shown in the fifth embodiment, and the diode current detection threshold Vth1 is changed according to the temperature detection as in the second embodiment. It has become.

  FIG. 9 is a plan view of the semiconductor chip 60 according to the present embodiment. As shown in FIG. 9, the semiconductor chip 60 includes a diode built-in DMOS element 100, a temperature sensitive diode element 50, a processing circuit unit 71, a current sensing element 61, a gate pad 62, a guard ring 63, and a source pad. 64 and a power supply pad 65.

  The source pad 64 is an electrode connected to a load. The power pad 65 is an electrode for applying a voltage from the power source to the feedback circuit 200. If the surface shown in FIG. 9 of the semiconductor chip 60 is the front surface, the drain pad is disposed on the back surface of the semiconductor chip 60. FIG. 10 shows an equivalent circuit having such a configuration.

  In FIG. 10, the processing circuit unit 71 includes a feedback circuit 200 and a sense resistor 30. The feedback circuit 200 is connected to the temperature sensitive diode element 50 shown in FIG. According to this, a constant current is supplied from the feedback circuit 200 to the temperature-sensitive diode element 50, and the forward voltage Vm of the temperature-sensitive diode element 50 that changes according to the temperature is input to the feedback circuit 200 as described above. .

  Similar to the second embodiment, the feedback circuit 200 has a first diode current detection threshold Vth1 and a second diode current detection threshold Vth1 'that is larger than the first diode current detection threshold Vth1. When the feedback circuit 200 determines that the forward voltage Vm input from the temperature-sensitive diode element 50 exceeds the temperature threshold value indicating the high temperature state of the diode built-in DMOS element 100, the feedback circuit 200 detects the first diode current detection threshold value Vth1 instead of the first diode current detection threshold value Vth1. The two-diode current detection threshold Vth1 ′ is compared with the potential difference Vs across the sense resistor 30.

  That is, as shown in FIG. 11, when the diode built-in DMOS element 100 is in a high temperature state, the feedback circuit 200 causes a current to flow through the diode element 121 even if the current flowing through the diode element 121 is very small. Make it easier to determine that Thereby, the feedback circuit 200 drives the DMOS element 21 a even when a minute current flows through the diode element 121, so that no forward current flows through the diode element 121.

  As described above, during a high-temperature operation in which the loss of the diode element 121 is a problem, the feedback current circuit 200 lowers the diode current detection threshold value and prevents the diode element 121 from increasing in DC current even in a small current region, thereby generating heat of the diode element 121. Can be further suppressed.

(Seventh embodiment)
In the present embodiment, only parts different from the fifth embodiment will be described. The present embodiment is characterized in that the noise tolerance is improved as compared with the case where the potential difference Vs vibrates due to noise.

  Therefore, the feedback circuit 200 has a diode current detection threshold Vth1 ″ that is larger than the diode current detection threshold Vth1. Here, the diode current detection threshold Vth1 is set as the first diode current detection threshold, and Vth1 ″ is set as the third diode current detection threshold.

  Then, as shown in FIG. 12, when the value of the potential difference Vs changes to the negative side, the feedback circuit 200 determines whether to drive the DMOS element 111 with the first diode current detection threshold value Vth1. On the other hand, when the value of the potential difference Vs changes to the positive side, the feedback circuit 200 determines whether or not to drive the DMOS element 111 based on the third diode current detection threshold Vth1 ″. Thus, the feedback circuit 200 operates like a Schmitt circuit.

  Note that “the value of the potential difference Vs changes to the negative side” refers to a case where the value of the potential difference Vs changes so as to decrease. Similarly, “the value of the potential difference Vs changes to the positive side” indicates a case where the value of the potential difference Vs changes so as to increase.

  As a result, even if the potential difference Vs may vibrate due to noise, a noise margin is provided between the first diode current detection threshold Vth1 and the third diode current detection threshold Vth1 ″. On / off of 111 is not switched, and a semiconductor device resistant to noise can be realized.

(Eighth embodiment)
In the present embodiment, only parts different from the fifth to seventh embodiments will be described. In the fifth to seventh embodiments, the semiconductor device can self-diagnose the current flowing through the diode element 121 and turn on / off the DMOS element 111 to reduce the DC loss of the diode element 121. However, the present embodiment is characterized in that the DMOS element 111 functions as a switching element.

  FIG. 13 is a circuit diagram of the semiconductor device according to the present embodiment. As shown in this figure, the output of the feedback circuit 200 is input to the OR circuit 400. The OR circuit 400 is supplied with a switching signal for switching the DMOS element 111 from an external control circuit.

  Therefore, when a current flows through the diode element 121, the feedback circuit 200 inputs the drive signal for turning on the DMOS element 111 to the OR circuit 400, so that the DMOS element 111 is turned on. Therefore, as described in the fifth embodiment. Furthermore, as indicated by an arrow 500 shown in FIG. 13, a current flows from the source to the drain of the DMOS element 111, and the loss of the forward voltage Vf of the diode element 121 is reduced.

  On the other hand, when the feedback circuit 200 does not detect that the current is flowing through the diode element 121, when the DMOS element 111 functions as a switching element, an external control circuit sends a switching signal for turning on the DMOS element 111 to the OR circuit 400. When input, the OR circuit 400 turns on the DMOS element 111. As a result, a current flows from the drain to the source of the DMOS element 111 as indicated by an arrow 600 shown in FIG. 13, and the DMOS element 111 functions as a switching element.

  As described above, the DMOS element 111 provided in the semiconductor device can be used not only for reducing DC loss of the diode element 121 but also as a switching element. The OR circuit 400 corresponds to the driving means of the present invention.

(Ninth embodiment)
In the present embodiment, only parts different from the fifth embodiment will be described. The present embodiment is characterized in that the feedback circuit 200 has a hysteresis characteristic.

  FIG. 14A shows the relationship between the drain current Id flowing through the drain of the DMOS element 111 and the potential difference Vs generated at both ends of the sense resistor 30. As shown in this figure, when the drain current Id is positive and the DMOS element 111 is on (Vg = ON), the drain current Id and the potential difference Vs have a proportional relationship. On the other hand, when the drain current Id is negative, the potential difference Vs with respect to the drain current Id is different depending on whether the DMOS element 111 is on (Vg = ON) or off (Vg = OFF).

  From the relationship shown in FIG. 14A, the feedback circuit 200 has a first diode current detection threshold value Vth1 corresponding to the potential difference Vs when the drain current flowing through the DMOS element 111 is the first drain current value Id1. is doing. Furthermore, the feedback circuit 200 corresponds to the potential difference Vs when the drain current is the second drain current value Id2 larger than the first drain current value Id1, and the third diode current detection larger than the first diode current detection threshold Vth1. It has a threshold value Vth1 ″. The first diode current detection threshold value Vth1 and the third diode current detection threshold value Vth1 ″ are used to determine that a current is flowing through the diode element 121.

  The first diode current detection threshold value Vth1 and the third diode current detection threshold value Vth1 ″ are set as follows. First, the relationship shown in FIG. 14A is acquired by measurement. Subsequently, in the relationship shown in FIG. 14A, a first drain current value Id1 is determined, and a second drain current value Id2 larger than the first drain current value Id1 is determined. The potential difference Vs at the first drain current value Id1 is set to the first diode current detection threshold Vth1, and the potential difference Vs at the second drain current value Id2 is set to the third diode current detection threshold Vth1 ''. . The feedback circuit 200 includes the first diode current detection threshold value Vth1 and the third diode current detection threshold value Vth1 ″ set as described above.

  Here, since each of the first drain current value Id1 and the second drain current value Id2 is a negative raw value, the magnitude relationship is Id1 <Id2. If this is expressed as an absolute value, | Id1 |> | Id2 |. Further, since the first diode current detection threshold value Vth1 and the third diode current detection threshold value Vth1 ″ are both negative raw values, the magnitude relationship is Vth1 <Vth1 ″. When this is expressed as an absolute value, | Vth1 |> | Vth1 '' |

  Then, the feedback circuit 200 performs the determination using the first diode current detection threshold Vth1 and the third diode current detection threshold Vth1 ″. As described above, the threshold values Vth1 and Vth1 ″ are derived from the first drain current value Id1 and the second drain current value Id2, respectively. Therefore, the feedback circuit 200 performs feedback control on the DMOS element 111 based on the conditions of Vth1 <Vth1 ″ (| Vth1 |> | Vth1 ″ |) and Id1 <Id2 (| Id1 |> | Id2 |). Will be performed.

  Next, control of the feedback circuit 200 having each determination threshold will be described with reference to FIG. FIG. 14B is a diagram showing the relationship among the potential difference Vs across the sense resistor 30, the first diode current detection threshold Vth1, the third diode current detection threshold Vth1 ″, and the output of the feedback circuit 200.

  As shown in FIG. 14B, when the value of the potential difference Vs changes to the negative side, the feedback circuit 200 compares the first diode current detection threshold Vth1 with the potential difference Vs generated at both ends of the sense resistor 30. It is determined whether or not the DMOS element 111 is driven. When the potential difference Vs is larger than the first diode current detection threshold Vth1, the feedback circuit 200 keeps the gate drive of the DMOS element 111 stopped. When the potential difference Vs is smaller than the first diode current detection threshold Vth1, the feedback circuit 200 drives the DMOS element 111 with a gate.

  On the other hand, when the value of the potential difference Vs changes to the positive side, the feedback circuit 200 compares the third diode current detection threshold Vth1 ″ with the potential difference Vs generated at both ends of the sense resistor 30 to drive the DMOS element 111. Determine whether or not. When the potential difference Vs is larger than the third diode current detection threshold Vth1 ″, the feedback circuit 200 stops the gate driving of the DMOS element 111. When the potential difference Vs is smaller than the third diode current detection threshold Vth1 ″, the feedback circuit 200 keeps the DMOS element 111 driven by the gate.

  Note that “the value of the potential difference Vs changes to the negative side” means that the value of the potential difference Vs changes so as to decrease and the value increases to the negative side. Similarly, “the value of the potential difference Vs changes to the positive side” means that the value of the potential difference Vs changes so as to increase, and the value increases to the plus side.

  As described above, the feedback circuit 200 has a hysteresis characteristic, and controls on / off of the DMOS element 111 between the first diode current detection threshold value Vth1 and the third diode current detection threshold value Vth1 ″.

  In the control of the feedback circuit 200 as described above, as shown in FIG. 14B, when the potential difference Vs changes to the negative side and exceeds the first diode current detection threshold Vth1, the DMOS element 111 is turned on. As shown in (a), the potential difference Vs has a characteristic of Vg = ON. Therefore, the value of the potential difference Vs increases as the DMOS element 111 is turned on. Since the potential difference Vs is a negative value, “the potential difference Vs increases” is equivalent to “the absolute value of the potential difference Vs decreases”.

  Thus, even when the DMOS element 111 is turned on and the value of the potential difference Vs increases, the potential difference Vs is equal to the first drain current value Id1 corresponding to the first diode current detection threshold Vth1 and Vg shown in FIG. = A value that intersects the ON waveform. This value is a value between the third diode current detection threshold Vth1 ″ and the first diode current detection threshold Vth1, and does not exceed the third diode current detection threshold Vth1 ″. If exceeded, the output of the feedback circuit 200 becomes Low as shown by the dotted arrow in FIG. 14B, and the state where the DMOS element 111 is on (Vg = ON) is turned off. However, as described above, since the potential difference Vs does not exceed the third diode current detection threshold Vth1 ″, the DMOS element 111 is not turned off and the on state is maintained. That is, the gate does not turn off again.

  In the above description, it has been described that the DMOS element 111 is not turned off again when the DMOS element 111 is switched from off to on. However, the same applies to the case where the DMOS element 111 is switched from on to off. In this case, as shown in FIG. 14A, when the DMOS element 111 is switched from on to off, the value of the potential difference Vs decreases. However, the potential difference Vs does not become smaller than the first diode current detection threshold Vth1. That is, as shown in FIG. 14B, the potential difference Vs does not become smaller than the first diode current detection threshold value Vth1, and the output of the feedback circuit 200 does not become Hi, and the DMOS element 111 is in an off state. Maintained.

  As described above, in the present embodiment, the value of the first diode current detection threshold Vth1 with respect to the first drain current value Id1 is set, and the third diode current with respect to the second drain current value Id2 larger than the first drain current value Id1. A detection threshold Vth1 ″ is set. Thereby, when switching on / off of the DMOS element 111, it is not turned off when it is turned on, and is not turned on when it is turned off. That is, it is possible to prevent oscillation in which the gate of the DMOS element 111 is repeatedly turned on / off.

  For example, Japanese Patent Laid-Open No. 2004-208407 discloses a synchronous rectification method in which a diode current is detected and a gate is turned on by a synchronous rectification circuit using a DMOS element. However, in the present embodiment, in the feedback circuit 200, each drain current value and each threshold value have Vth1 <Vth1 ″ (| Vth1 |> | Vth1 ″ |) and Id1 <Id2 (| Id1 |> | Id2 |) The conditions are set. For this reason, as described above, the oscillation of the DMOS element 111 can be reliably prevented. As described above, by providing the control of the DMOS element 111 of the feedback circuit 200 with a hysteresis characteristic, the problem of oscillation of the DMOS element 111 can be solved.

  As for the correspondence between the description of this embodiment and the description of the claims, the third diode current detection threshold Vth1 ″ corresponds to the second diode current detection threshold of the claims. The feedback circuit 200 and the sense resistor 30 correspond to the feedback means in the claims.

(10th Embodiment)
In the present embodiment, only parts different from the ninth embodiment will be described. In this embodiment, the semiconductor device shown in the ninth embodiment is provided with the temperature-sensitive diode element 50 shown in FIGS. 9 and 10. Thus, a forward voltage corresponding to the temperature of heat generated by the operation of the diode built-in DMOS element 100 is input to the feedback circuit 200.

  The feedback circuit 200 has a temperature correction map for the element temperature T of the temperature sensitive diode element 50 input from the temperature sensitive diode element 50. FIG. 15A shows the temperature correction map. Here, the element temperature T is the temperature of the element converted from the forward voltage of the temperature-sensitive diode element 50. Actually, the temperature correction map is a map in which each threshold is set for the forward voltage.

  As shown in FIG. 15A, the first diode current detection threshold value Vth1 and the third diode current detection threshold value Vth1 ″ are the first and third diode current detection threshold values as the temperature of the temperature sensitive diode element 50 changes. The values of Vth1 and Vth1 ″ have changed.

  Therefore, when the feedback circuit 200 compares the first and third diode current detection thresholds Vth1 and Vth1 ″ with the potential difference Vs, the feedback circuit 200 uses the temperature correction map to determine the first and third diode current detection thresholds Vth1, The comparison is performed by correcting Vth1 ″ to a value corresponding to the forward voltage.

  FIG. 15B shows the output of the feedback circuit 200 with respect to the potential difference Vs. As shown in this figure, when the values of the first and third diode current detection threshold values Vth1 and Vth1 ″ are corrected by the temperature correction map, the widths are changed to the first and third diode current detection threshold values Vth1 and Vth1 ″. Will be provided.

  As described above, by controlling the feedback circuit 200 after correcting the values of the first and third diode current detection thresholds Vth1 and Vth1 ″, synchronous rectification can always be performed with a constant current.

  As for the correspondence between the description of this embodiment and the description of the claims, the third diode current detection threshold Vth1 ″ corresponds to the second diode current detection threshold of the claims.

(Other embodiments)
In each of the above-described embodiments, the case where the IGBT unit 21 is PWM-controlled has been described. However, this shows an example of the control, and for example, the IGBT element 21a may be driven fully on. The same applies to the driving of the DMOS element 111 according to the eighth embodiment.

  In the first to fourth embodiments, the feedback circuit 40 determines both the current flowing through the diode element 22a and the excess current flowing through the IGBT element 21a. However, in the semiconductor device, the feedback circuit 40 is connected to the diode section 22. It may be configured to perform only the determination of the flowing current. In this case, it is not necessary to provide the IGBT sensing element 21b in the IGBT section 21, and the semiconductor device can be configured to include the IGBT element 21a and the diode section 22 as the diode built-in IGBT element 20. In addition, you may use a Hall element as what detects the electric current component which flows into the diode element 21a. The same applies to the fifth to eighth embodiments regarding the use of the Hall element.

  Further, a circuit configuration may be adopted in which the current flowing through the diode element 22a is directly detected without using the diode sense element 22b. In this case, as a semiconductor device, the current flowing in the diode built-in IGBT element 20 and the diode element 22a is detected. When no current flows in the diode element 22a, the PWM gate signal input from the outside is allowed to pass. In the case where a current flows through the diode element 22a, a configuration including means (for example, the AND circuit 10, the sense resistor 30, and the feedback circuit 40) for stopping the passage of the PWM gate signal may be used. In this case, a circuit configuration in which the sense resistor 30 is provided as a means for permitting / stopping the passage of the PWM gate signal may be employed. Further, a circuit configuration in which a current flowing through the diode sense element 22b flows through the sense resistor 30 may be employed. Of course, a circuit configuration in which the temperature-sensitive diode element 50 is provided in such a circuit configuration is also possible. Such a circuit configuration that directly detects the current flowing through the diode element 121 without using the diode sense element 122 can also be adopted in the fifth to eighth embodiments.

  In each of the above embodiments, the diode current detection thresholds Vth1, Vth1 ′, and Vth1 ″ are negative values, and the overcurrent detection threshold Vth2 is a positive value, but this is an example, However, it is not limited to these. The diode current detection thresholds Vth1, Vth1 ′, Vth1 ″ and the overcurrent detection threshold Vth2 are voltage values, but the feedback means constituted by the AND circuit 10, the sense resistor 30, and the feedback circuit 40 is a diode element. In the case where it is detected that a current flows through 22a, each of the threshold values is set as a current value.

  In the second and sixth embodiments, as shown in FIGS. 3 and 10, a circuit form in which four temperature-sensitive diode elements 50 are directly connected is shown, but the number of temperature-sensitive diode elements 50 is as follows. It is an example and may be plural or one.

  The feedback circuit 200 that functions like a Schmitt circuit in the seventh embodiment may be employed in the feedback circuit 200 that performs temperature detection in the sixth embodiment.

  The feedback circuit 200 having hysteresis characteristics according to the ninth and tenth embodiments may be applied to the semiconductor device according to the eighth embodiment.

  The temperature correction map shown in the tenth embodiment may be applied to the sixth embodiment, for example. Thereby, fine temperature control can be performed.

  FIG. 16 is an example of a cross-sectional view of the DMOS element 111. As shown in this figure, a P-type well 710 is formed in the surface layer portion of the N-type substrate 700, and an N + type source layer 720 is formed in the surface layer portion of the P-type well 710. A large number of trench gate structures 730 are formed so as to penetrate the N + type source layer 720 and the P type well 710 and reach the N type substrate 700.

  The trench gate structure 730 is formed through the N + type source layer 720 and the P type well 710 to reach the N type substrate 700, a gate insulating film formed on the wall surface of the trench, and formed on the gate insulating film. And a gate electrode formed.

  In addition, a P + type body region 740 that penetrates the N + type source layer 720 and reaches the P type well 710 is formed between the trench gate structures 730. Further, an N + type layer 750 is formed on the side opposite to the surface on which the P type well 710 is formed in the N type substrate 700. The N + type layer 750 is a layer that becomes a cathode. As described above, the DMOS element 111 shown in FIG. 16 can be employed.

1 is a circuit diagram of a semiconductor device according to a first embodiment of the present invention. In 1st Embodiment, it is the figure which showed the potential difference Vs of the both ends of a sense resistor, the diode current detection threshold Vth1, the overcurrent detection threshold Vth2, and the relationship of the output of a feedback circuit. It is a circuit diagram of a semiconductor device concerning a 2nd embodiment of the present invention. In 2nd Embodiment, it is the figure which showed the potential difference Vs of the both ends of a sense resistor, the 1st diode current detection threshold Vth1, the 2nd diode current detection threshold Vth1 ', the overcurrent detection threshold Vth2, and the relationship of the output of a feedback circuit. . (A) is the whole semiconductor chip schematic diagram concerning 3rd Embodiment, (b) is a circuit diagram of the semiconductor device accommodated in (a). (A) is the whole semiconductor chip schematic diagram concerning 4th Embodiment, (b) is the figure which showed the back surface structure of the semiconductor chip shown by (a). It is a circuit diagram of a semiconductor device concerning a 5th embodiment of the present invention. In 5th Embodiment, it is the figure which showed the potential difference Vs of the both ends of a sense resistance, the diode electric current detection threshold value Vth1, and the relationship of the output of a feedback circuit. It is a top view of the semiconductor chip concerning a 6th embodiment of the present invention. It is a circuit diagram of the semiconductor device which concerns on 6th Embodiment of this invention. In 6th Embodiment, it is the figure which showed the potential difference Vs of the both ends of a sense resistance, the 1st diode current detection threshold value Vth1, the 2nd diode current detection threshold value Vth1 ', and the relationship of the output of a feedback circuit. In the seventh embodiment, it is a diagram showing the relationship between the potential difference Vs across the sense resistor, the first diode current detection threshold Vth1, the third diode current detection threshold Vth1 '', and the output of the feedback circuit. It is a circuit diagram of the semiconductor device which concerns on 8th Embodiment of this invention. (A) is the figure which showed the relationship between the potential difference Vs and the drain current Id of a DMOS element, (b) is the figure which showed the relationship between the potential difference Vs and the output of a feedback circuit. (A) is the figure which showed the temperature correction map, (b) is the figure which showed the relationship between the electric potential difference Vs and the output of a feedback circuit. In other embodiment, it is the figure which showed an example of the cross section of a DMOS element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 AND circuit 20 IGBT element with built-in diode 21 IGBT part 21a IGBT element 21b IGBT sense element 22 Diode part 22a Diode element 22b Diode sense element 30 Sense resistor 40 Feedback circuit part 50 Temperature sensitive diode element 62 Gate pad 63 Guard ring

Claims (16)

A diode built-in IGBT element (20) in which a diode element (22a) and an IGBT element (21a) driven by a drive signal input to a gate are provided on the same semiconductor substrate;
The drive signal input from the outside is passed through and input to the gate of the IGBT element (21a). The current flowing through the diode element (22a) is detected, and the current flows through the diode element (22a). If not, feedback means (10, 30, 40) that permits passage of the drive signal input from the outside and stops passage of the drive signal when current flows through the diode element (22a). A semiconductor device comprising:   The feedback means (10, 30, 40) includes a sense resistor (30) for detecting a current flowing through the diode element (22a), and determines that a current is flowing through the diode element (22a). A first diode current detection threshold value (Vth1) used for the purpose, and the potential difference (Vs) between both ends of the sense resistor (30) is compared with the first diode current detection threshold value (Vth1). When Vs) is larger than the first diode current detection threshold (Vth1), the drive signal input from the outside is allowed to pass, while the potential difference (Vs) is greater than the first diode current detection threshold (Vth1). 2. The semiconductor device according to claim 1, wherein when the value is smaller, the passage of the drive signal is stopped.   The diode built-in IGBT element (20) has a diode sense element (22b) through which a current proportional to a current flowing through the diode element (22a) flows, and the current flowing through the diode sense element (22b) is converted into the sense resistor (22b). 30. The semiconductor device according to claim 2, wherein the semiconductor device flows to 30). A temperature-sensitive diode element (50) for outputting a forward voltage corresponding to the temperature of heat generated by the operation of the diode-embedded IGBT element (20);
The feedback means (10, 30, 40) has a second diode current detection threshold value (Vth1 ′) that is larger than the first diode current detection threshold value (Vth1), and from the temperature sensitive diode element (50). When the forward voltage of the input temperature-sensitive diode element (50) exceeds the temperature threshold value indicating the high temperature state of the diode built-in IGBT element (20), the potential difference (Vs) across the sense resistor (30) and the first 4. The semiconductor device according to claim 2, wherein the two-diode current detection threshold value (Vth1 ′) is compared.   The feedback means (10, 30, 40) detects a current flowing through the IGBT element (21a), and when an excess current does not flow through the IGBT element (21a), it passes the drive signal input from the outside. 5, while an excess current flows through the IGBT element (21 a), the passage of the drive signal is stopped. 5. Semiconductor device.   The feedback means (10, 30, 40) has an overcurrent detection threshold value (Vth2) used to determine that an excess current is flowing in the IGBT element (21a), and the sense resistor (30 ) And the overcurrent detection threshold value (Vth2). If the potential difference (Vs) is smaller than the overcurrent detection threshold value (Vth2), the drive signal input from outside is compared. 6. The semiconductor device according to claim 5, wherein the passage of the drive signal is stopped when the potential difference (Vs) is larger than the overcurrent detection threshold (Vth2) while allowing the passage. apparatus.   The diode built-in IGBT element (20) has an IGBT sense element (21b) through which a current proportional to a current flowing through the IGBT element (21a) flows, and the current flowing through the IGBT sense element (21b) flows into the sense resistor (21b). 30. The semiconductor device according to claim 5, wherein the semiconductor device is configured to flow to 30). A diode built-in DMOS element (100) in which a diode element (121) and a DMOS element (111) driven by a drive signal input to a gate are provided on the same semiconductor substrate;
When the current flowing through the diode element (121) is detected and no current flows through the diode element (121), the driving of the DMOS element (111) is stopped while the diode element (121) is moved forward. Feedback means (200) for driving the DMOS element (111) to flow a current in the same direction as the forward current to the diode element (121) to the DMOS element (111) when a current is flowing A semiconductor device comprising:   The feedback means (200) includes a sense resistor (30) for detecting a current flowing through the diode element (121), and is used for determining that a current is flowing through the diode element (121). 1 diode current detection threshold (Vth1), the potential difference (Vs) across the sense resistor (30) is compared with the first diode current detection threshold (Vth1), and the potential difference (Vs) is When it is larger than the first diode current detection threshold (Vth1), the driving of the DMOS element (111) is stopped, and when the potential difference (Vs) is smaller than the first diode current detection threshold (Vth1), the DMOS element 9. The semiconductor device according to claim 8, wherein (111) is driven.   The diode built-in DMOS element (100) includes a diode sense element (122) through which a current proportional to a current flowing through the diode element (121) flows. The current flowing through the diode sense element (122) is converted into the sense resistor (122). The semiconductor device according to claim 9, wherein a potential difference (Vs) is generated in the sense resistor (30) by flowing to (30). A temperature-sensitive diode element (50) for outputting a forward voltage corresponding to the temperature of heat generated by the operation of the diode built-in DMOS element (100);
The feedback means (200) has a second diode current detection threshold (Vth1 ′) larger than the first diode current detection threshold (Vth1), and the sensitivity input from the temperature-sensitive diode element (50). When the forward voltage of the warm diode element (50) exceeds the temperature threshold indicating the high temperature state of the diode built-in DMOS element (100), the potential difference (Vs) across the sense resistor (30) and the second diode current detection 11. The semiconductor device according to claim 9, wherein the semiconductor device is compared with a threshold value (Vth1 ′). The feedback means (200) has a third diode current detection threshold value (Vth1 '') larger than the first diode current detection threshold value (Vth1),
When the value of the potential difference (Vs) changes to the negative side, the first diode current detection threshold value (Vth1) is compared with the potential difference (Vs) to determine whether to drive the DMOS element (111). On the other hand, when the value of the potential difference (Vs) changes to the positive side, the third diode current detection threshold value (Vth1 ″) is compared with the potential difference (Vs) to drive the DMOS element (111). The semiconductor device according to claim 9, wherein it is determined whether or not. The feedback means (200) includes:
A sense resistor (30) for detecting a current flowing through the diode element (121);
The sense resistor (30) is used to determine that a current flows through the diode element (121), and the drain current flowing through the DMOS element (111) is a first drain current value (Id1). The first diode current detection threshold value (Vth1) corresponding to the potential difference (Vs) at both ends of the first and second drain current values (Id2) larger than the first drain current value (Id1). A second diode current detection threshold (Vth1 ″) corresponding to a potential difference (Vs) and larger than the first diode current detection threshold (Vth1),
When the value of the potential difference (Vs) changes to the negative side, the first diode current detection threshold value (Vth1) is compared with the potential difference (Vs), and the potential difference (Vs) is compared with the first diode current detection threshold value (Vs1). When the potential difference (Vs) is smaller than the first diode current detection threshold value (Vth1), the DMOS element (111) is stopped when the gate driving of the DMOS element (111) is stopped. Gate drive,
When the value of the potential difference (Vs) changes to the positive side, the second diode current detection threshold (Vth1 ″) is compared with the potential difference (Vs), and the potential difference (Vs) is detected by the second diode current detection. When the threshold voltage (Vth1 ″) is greater than the threshold value (Vth1 ″), the gate drive of the DMOS element (111) is stopped, while when the potential difference (Vs) is smaller than the second diode current detection threshold value (Vth1 ″), the DMOS element ( The semiconductor device according to claim 8, wherein 111) is left gate-driven.   The diode built-in DMOS element (100) includes a diode sense element (122) through which a current proportional to a current flowing through the diode element (121) flows. The current flowing through the diode sense element (122) is converted into the sense resistor (122). The semiconductor device according to claim 13, wherein a potential difference (Vs) is generated in the sense resistor (30) by flowing to (30). A temperature-sensitive diode element (50) for outputting a forward voltage corresponding to the temperature of heat generated by the operation of the diode built-in DMOS element (100);
The feedback means (200) is configured to detect the first and second diode current detection thresholds (Vth1) with respect to the temperature of the element converted from the forward voltage of the temperature-sensitive diode element (50) as the temperature of the element changes. , Vth1 ″) has a temperature correction map in which the value changes, and when the first and second diode current detection thresholds (Vth1, Vth1 ″) and the potential difference (Vs) are compared, the temperature correction map is used. 15. The comparison is performed by correcting the first and second diode current detection thresholds (Vth1, Vth1 '') to values according to a temperature change of the element by using a map. Semiconductor device.   A driving signal for driving the DMOS element (111) is inputted from the feedback means (200), and a switching signal for driving the DMOS element (111) is inputted from the outside. Driving means (400) for causing the DMOS element (111) to function as a switching element by driving the DMOS element (111) according to the switching signal when the switching signal is input without being input to the driving signal. 16. The semiconductor device according to claim 8, further comprising:

Images