JP4904851B2 - Semiconductor device with overvoltage protection circuit - Google Patents

Description

  The present invention relates to an overvoltage protection circuit that protects a semiconductor integrated circuit when an unexpected overvoltage is applied, and a semiconductor device including the overvoltage protection circuit.

  2. Description of the Related Art Conventionally, an electrical component or an electronic component such as a semiconductor integrated circuit or its control circuit is provided with an overvoltage protection circuit in order to prevent malfunction or damage due to overvoltage or static electricity caused by fluctuations in power supply voltage.

  The prior art of such an overvoltage protection circuit is disclosed in Patent Document 1.

Japanese Patent Laid-Open No. 5-183109 (Description of FIG. 1, FIG. 2 and paragraph (0008))

  In the overvoltage protection circuit of the prior art, an overvoltage within an assumption can be avoided within an allowable voltage range of the overvoltage protection circuit. However, when an unexpected overvoltage is applied, damage inside the integrated circuit and an external circuit It is thought that this leads to secondary damage.

  An object of the present invention is to provide a semiconductor device including an overvoltage protection circuit capable of avoiding damage inside an integrated circuit and secondary damage to an external circuit even when an unexpected overvoltage is applied.

According to the semiconductor device of the present invention, in the overvoltage protection circuit, the first wiring and the second wiring arranged opposite to each other are melted by an overvoltage higher than the element breakdown voltage at the input end , and the first wiring and the second wiring are short-circuited. Thus, damage to the protected circuit and secondary damage inside or outside the integrated circuit are avoided.

  According to the present invention, it is possible to protect from overvoltage, and it is possible to avoid secondary damage of a circuit outside the integrated circuit even when an unexpected overvoltage is applied.

  The details of the present invention will be described with reference to the drawings and examples.

  This embodiment will be described with reference to FIGS. FIG. 2 is an explanatory diagram of a motor drive device using the inverter IC of this embodiment. 2 is an inverter IC, 6 is a motor, 7 is a commercial AC power supply, 8 is a rectifying and smoothing circuit, 9 is a microcomputer as a control unit, 10 is a position detection circuit for detecting the position of the rotor of the motor, and 11 is A drive control circuit unit built in the inverter IC, 12 is an output stage power element unit, Vs is an output stage power element power supply voltage, and Vcc is a drive control circuit power supply voltage.

  In the inverter IC 5 of this embodiment, the output stage power element unit 12 and the drive control circuit unit 11 are arranged on a dielectric isolation substrate having a silicon single crystal portion insulated and separated by an insulation isolation layer formed on a silicon semiconductor substrate. Has been.

  In FIG. 2, the drive control circuit unit 11 includes a drive circuit unit, a protection circuit unit, a level shift circuit unit, and a logic circuit unit (not shown), and receives an output signal from the microcomputer 9 to receive the output stage power element unit 12. For example, a gate drive signal subjected to pulse width modulation (PWM) is transmitted. The protection circuit unit detects overheating, overcurrent, low voltage, and the like, and sends a detection signal to the logic unit of the microcomputer 9 and the drive control circuit unit 11 to limit the output of the output stage power element unit 12.

  The output stage power element section 12 includes three upper and lower arms each having a totem pole connection of IGBTs or power MOSFETs, which are power semiconductor elements of the upper and lower arms, and provides three-phase alternating currents of variable U phase, V phase, and W phase. The power is output and the load motor 6 is driven. The rectifier circuit unit 8 rectifies the commercial AC power supply 7 rated at 100 V to 120 V or 200 V to 240 V, and supplies the output stage power element power supply voltage Vs to the output stage power element unit 12. The drive control circuit power supply voltage Vcc is 15 V in this embodiment, but is not limited to this voltage.

  FIG. 1 is a circuit diagram of an overvoltage protection circuit provided in the protection circuit unit of the drive control circuit unit 11 of the inverter IC 5 of this embodiment. In FIG. 1, reference numeral 2 is a Zener diode, 3 is a resistor, 4 is an NPN transistor, and Vcc is a drive control circuit power supply voltage. The cathode of the Zener diode 2 is connected to the drive control circuit power supply voltage Vcc, and the anode is connected to one end of the resistor 3 and the base of the NPN transistor 4. Further, the collector of the NPN transistor 4 is connected to the drive control circuit power supply voltage Vcc and is at the same potential as the cathode of the Zener diode 2, and the emitter of the NPN transistor 4 is connected to the other end of the resistor 3, and in FIG. It is connected to the potential GL. Reference numeral 1 in FIG. 1 shows an outline of the Al wiring region 1 of a power supply voltage line (abbreviated as a Vcc power supply voltage line) of the drive control circuit power supply voltage Vcc and a line of ground potential GL (abbreviated as ground potential line). FIG. 3 is a plan view of the shape, and FIG. 4 is a cross-sectional view taken along line II ′ of FIG. The hatched portions A and B in FIG. 3 and FIG. 4 are low resistance wirings, and are Al wirings here.

  Hereinafter, the operation of the overvoltage protection circuit shown in FIG. 1 will be described. In this embodiment, the Zener voltage of the Zener diode 2 between the drive control circuit power supply voltage Vcc terminal and the ground potential GL terminal (abbreviated as Vcc-GL) is equal to or higher than the maximum rated voltage between the terminals, and Set the voltage below the element breakdown voltage between terminals. When a voltage equal to or higher than the Zener voltage of the Zener diode 2 is applied between Vcc and GL due to an overvoltage or the like, a current flows through the base of the NPN transistor 4 and the NPN transistor 4 is turned on. At this time, the voltage between Vcc and GL is clamped with a Zener voltage.

  A method for preventing secondary damage to a protected circuit, an integrated circuit, an in-substrate circuit, and the like when an unexpectedly high overvoltage that is equal to or higher than the element breakdown voltage between the terminals is applied between Vcc and GL. As shown in FIG. 1, the Al wiring region 1 is laid out as shown in FIGS. The Al wiring in the Al wiring region 1 is laid out with a wiring width, a thickness, and a distance between the wirings that melt due to overcurrent and short-circuit between the wirings. In this case, the low resistance wiring A and the low resistance wiring B are formed so as to extend opposite to each other on the insulator, and the low resistance wiring A and the low resistance wiring B are insulated by an insulating layer. .

  When an unexpected overvoltage exceeding the preset device breakdown voltage is applied, the bipolar transistor 4 is turned on, and an overcurrent flows between Vcc and GL. At this time, the Al wiring is melted by the overcurrent, and the desired layout structure is formed so that the wiring is short-circuited by the melted Al. Therefore, the Vcc-GL is short-circuited and the voltage between the terminals is lowered. Since the drive control circuit 11 of the present embodiment includes a low voltage protection circuit (not shown), secondary damage to the drive control circuit unit 11 and the output stage power element unit 12 is prevented by lowering the voltage between Vcc and GL. This can prevent damage to external elements and circuits connected to the inverter IC5.

  In this embodiment, a single Zener diode is used. However, the Zener voltage for clamping between terminals may be the number of elements that is not less than the maximum rated voltage between terminals and less than the withstand voltage between terminals. There is no limit. Further, when a plurality of Zener diodes are connected in series, the Zener voltage of each Zener diode may be the same or different. Furthermore, even if the number of elements of the resistor and the NPN transistor is reached, the number is not limited.

  In this embodiment, the inverter IC 5 formed on the dielectric isolation substrate has been described. However, instead of the dielectric isolation substrate, the IC formed on the SOI semiconductor substrate including the silicon single crystal portion insulated and separated by the insulation isolation layer. It may be.

  This embodiment will be described with reference to FIGS. FIG. 5 is a plan view of the Al wiring region 1 of FIG. 1, and FIG. 6 is a cross-sectional view of the II-II ′ portion of FIG. The hatched portions C and D in FIG. 5 and FIG. 6 are low resistance wirings, and here are Al wirings. Example 1 is the same as Example 1 except that the low resistance wiring is a multilayer wiring.

  In this embodiment, the low resistance wiring C and the low resistance wiring D intersect with each other as shown in FIGS. 5 and 6 through an insulating layer. When an unexpected overvoltage is applied, in this embodiment as well as in the first embodiment, the Al wiring is melted by a preset overcurrent, and a desired layout structure is formed so that the wiring is short-circuited by the melted Al. .

  This embodiment will be described with reference to FIG. In the present embodiment, instead of the inverter IC 5 of the first embodiment and the second embodiment, as shown in FIG. 7, a pre-driver IC 13 and an output stage power element 14 are used. Similar to Example 2.

  The pre-driver IC 13 includes a drive control circuit unit 11 formed on a dielectric isolation substrate. The drive control circuit unit 11 includes a drive circuit unit, a protection circuit unit, a level shift circuit unit, and a logic circuit unit (not shown). In response to the control signal generated by the microcomputer 9, for example, a pulse drive modulated (PWM) gate drive signal is sent to the output stage power element 14. The protection circuit unit detects overcurrent, overheat, low voltage, and the like, and sends a detection signal to the microcomputer 9 and the logic unit to limit the output of the output stage power element 14.

  The output stage power element 14 of the present embodiment has three arms in which the upper and lower arms IGBTs or power MOSFETs are connected by totem pole connection, and outputs a three-phase alternating current of U-phase, V-phase, and W-phase with variable frequency. Then, the load motor 6 is driven.

  The rectifier circuit unit 8 of this embodiment rectifies the commercial AC power supply 7 rated at 100 V to 120 V or 200 V to 240 V, and supplies the output stage power element power supply voltage Vs to the output stage power element 14. The drive control circuit power supply voltage Vcc is 15 V in this embodiment, but is not limited to this voltage.

  The pre-driver IC 13 of this embodiment also includes the overvoltage protection circuit shown in FIG. 1 of the first embodiment in the protection circuit section of the drive control circuit section 11, and further includes a low voltage protection circuit (not shown). When an unexpected high overvoltage is applied to the pre-driver IC 13 between Vcc and GL, the Al wiring in the Al wiring region 1 is melted and wiring is performed with the melted Al as in the first and second embodiments. A short circuit occurs between Vcc and GL, and a voltage between terminals decreases.

  In this embodiment, the pre-driver IC 13 formed on the dielectric isolation substrate has been described. However, instead of the dielectric isolation substrate, the pre-driver IC 13 is formed on an SOI semiconductor substrate including a silicon single crystal portion that is insulated and separated by an insulating isolation layer. IC may be sufficient.

1 is a circuit diagram of an overvoltage protection circuit according to Embodiment 1. FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 3 is a plan view of an Al wiring region of the overvoltage protection circuit according to the first embodiment. Sectional drawing of the II 'part of FIG. FIG. 6 is a plan view of an Al wiring region of the overvoltage protection circuit according to the second embodiment. Sectional drawing of the II-II 'part of FIG. FIG. 6 is an explanatory diagram of a motor driving device having a pre-driver IC according to a third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Al wiring area | region, 2 ... Zener diode, 3 ... Resistor, 4 ... NPN transistor, 5 ... Inverter IC, 6 ... Motor, 7 ... Commercial alternating current power supply, 8 ... Rectification smoothing circuit, 9 ... Microcomputer, 10 ... Position detection Reference numeral 11 is a drive control circuit section, 12 is an output stage power element section, 13 is a pre-driver IC, and 14 is an output stage power element.

Claims (8)

In a semiconductor integrated circuit comprising an output stage power element part and a drive control circuit part for driving the output stage power element part,
The output stage power element section includes three arms to which a power semiconductor element is connected to a totem pole,
The drive control circuit unit includes a drive circuit unit, a logic circuit unit, and a protection circuit unit,
In the protection circuit unit, the cathode of the Zener diode is connected to the input terminal of the power supply voltage in the protected circuit by the first wiring, and the anode of the Zener diode and the base of the bipolar transistor are connected to one end of the resistor. , said collector of the bipolar transistor is connected to the cathode of the Zener diode, the other end of the resistor and the emitter of the bipolar transistor is connected to a common potential by a second wire, the maximum rated voltage over and the input end A first overvoltage protection circuit that performs a protection operation when an overvoltage that is equal to or higher than the Zener voltage of the Zener diode set to be equal to or lower than the element breakdown voltage of the input terminal ;
When an overvoltage higher than the device withstand voltage is applied, the first wiring and the second wiring arranged opposite to each other are melted by a current flowing through the bipolar transistor, and the terminals are short-circuited to form an internal circuit of the semiconductor integrated circuit. A semiconductor integrated circuit comprising: a second protection circuit for avoiding element damage. The semiconductor integrated circuit according to claim 1,
The output stage power element portion and the drive control circuit portion are formed on the same silicon semiconductor substrate, and the silicon semiconductor substrate includes a silicon single crystal portion that is insulated and separated by an insulating separation layer,
The semiconductor integrated circuit, wherein the output stage power element portion and the drive control circuit portion are arranged in the silicon single crystal portion. The semiconductor integrated circuit according to claim 1,
A semiconductor integrated circuit, wherein a silicon semiconductor substrate having a silicon single crystal portion insulated and separated by the insulation separation layer is a dielectric separation semiconductor substrate. The semiconductor integrated circuit according to claim 1,
A semiconductor integrated circuit, wherein a silicon semiconductor substrate having a silicon single crystal portion insulated and separated by the insulating separation layer is an SOI semiconductor substrate. In a semiconductor integrated circuit including a drive control circuit unit for driving an output stage power element unit,
The drive control circuit unit includes a drive circuit unit, a logic circuit unit, and a protection circuit unit,
In the protection circuit unit, the cathode of the Zener diode is connected to the input terminal of the power supply voltage in the protected circuit by the first wiring, and the anode of the Zener diode and the base of the bipolar transistor are connected to one end of the resistor. , said collector of the bipolar transistor is connected to the cathode of the Zener diode, the other end of the resistor and the emitter of the bipolar transistor is connected to a common potential by a second wire, the maximum rated voltage over and the input end A first overvoltage protection circuit that performs a protection operation when an overvoltage that is equal to or higher than the Zener voltage of the Zener diode set to be equal to or lower than the element breakdown voltage of the input terminal ;
When an overvoltage higher than the device withstand voltage is applied, the first wiring and the second wiring arranged opposite to each other are melted by a current flowing through the bipolar transistor, and the terminals are short-circuited to form an internal circuit of the semiconductor integrated circuit. A semiconductor integrated circuit comprising: a second protection circuit for avoiding element damage. The semiconductor integrated circuit according to claim 5,
The drive control circuit portion is formed on a silicon semiconductor substrate, and the silicon semiconductor substrate includes a silicon single crystal portion that is insulated and separated by an insulating separation layer;
A semiconductor integrated circuit, wherein a drive control circuit portion is disposed in the silicon single crystal portion. The semiconductor integrated circuit according to claim 6,
A semiconductor integrated circuit, wherein a silicon semiconductor substrate having a silicon single crystal portion insulated and separated by the insulation separation layer is a dielectric separation semiconductor substrate. The semiconductor integrated circuit according to claim 6,
A semiconductor integrated circuit, wherein a silicon semiconductor substrate having a silicon single crystal portion insulated and separated by the insulating separation layer is an SOI semiconductor substrate.

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