JP5608329B2 - Surge current generator - Google Patents

Description

  The present invention relates to a surge current generator that controls an output current.

The surge current generator is a device that is used when a current surge test is performed on a device under test by generating an abruptly changing current. Such a current surge test is performed in a reliability confirmation test or the like in the manufacturing process of the semiconductor device. For example, in a reliability confirmation test for a two-terminal thyristor for surge current protection, a current surge test that applies a surge current having a large peak value in milliseconds to guarantee the current surge withstand characteristics during surge protection operation This is done for all products. (For example, refer to Patent Document 1 or 2).
In the conventional surge current generator 1 shown in FIG. 2, the capacitor C4 for charge charging is charged from the high voltage source Vh3 by turning on the switch 2 (SW1), and the device under test 90 (DUT) is charged. A current surge is applied through the limiting resistor Rs5. The application of the current surge is performed by switching the switching elements 61 to 64 (SW2a-SW2b and SW3a-SW3b) provided in the polarity switching unit 60 and inverting the direction of the current.

Japanese Utility Model Publication No. 61-131672 Japanese Utility Model Laid-Open No. 03-039183

  However, the surge current generator 1 having the configuration shown in this figure has a problem that it is difficult to realize when the application time is increased. For example, if the value of the limiting resistor Rs5 that limits the surge current ITSM is increased while securing the necessary surge current ITSM value, it is necessary to increase the power supply voltage to be applied. In order to cope with such a condition, a power supply facility that generates a high voltage is required, and the handling of the high voltage is limited, which makes it difficult to realize. Therefore, as a means for extending the discharge time, it is difficult to increase the value of the limiting resistor Rs5. Therefore, it is necessary to increase the capacitance of the charge charging capacitor C4. When the capacity of the capacitor C4 is increased, charging time is increased and self-heating is increased due to loss in the power supply because charging is performed at a high voltage. In order to cope with such a situation, it is necessary to extend a cycle of repeated tests or secure a sufficient heat radiation amount by introducing a cooling device for cooling the surge current generator. Due to these factors, there is a problem that the test efficiency is lowered and the test apparatus is enlarged.

  In view of the above, an object of the present invention is to provide a surge current generator that ensures the efficiency of a surge current test and has a simplified configuration.

In order to solve the above problems, the present invention provides a surge current generator that outputs a current to an object to be inspected, a power source that outputs the current, and a current that operates as a unit current source by controlling the current A control circuit; a selection control circuit that controls the supply of the current output from the current control circuit; and a polarity switching unit that switches a polarity of the current. The current control circuit is determined based on a reference potential The current is controlled to a predetermined current value according to the voltage, and the current of the current value is allowed to flow to the inspection target, and the voltage applied to both ends of the inspection target with one end grounded. Accordingly, the surge current generator is characterized in that the reference potential varies with respect to the ground potential .

Further, the present invention is a surge current generator for outputting a current to an object to be inspected, wherein a power source unit for outputting the current and a current shunted from the current output by the power source unit are controlled to be unit currents. A plurality of current control circuits that operate as a source, a plurality of selection control circuits that are provided corresponding to the current control circuits and that control the supply and interruption of the current by synchronizing the selected current control circuits; and a current adder for adding a current the current control circuit outputs, respectively, the current control circuit includes a constant the current to a predetermined current value corresponding to a predetermined voltage reference potential as a reference and current control, with flowing the current of the current value the the object to be inspected, according to a voltage applied to the both ends of the object to be inspected which is grounded at one end, said reference potential with respect to the potential of the ground varies Special A surge current generator to.

Further, the present invention is the above invention, wherein the current control circuit receives an active element that controls a current shunted from a current output from the power supply unit and a voltage based on a reference potential of the current control circuit. A first resistor for dividing the input voltage; a second resistor connected in series to the first resistor; and a discharge control capacitor element connected in parallel to the second resistor. A control signal generation unit configured to control the current to flow according to a voltage obtained by dividing the input voltage .

  Moreover, the present invention is characterized in that, in the above invention, a polarity switching unit that switches a polarity of a current supplied to the inspection target is provided.

According to the present invention, the surge current generator is a surge current generator that outputs current to an object to be inspected. In this surge current generator, the current control circuit operates as a unit current source by controlling the current output from the power supply unit. The selection control circuit controls the supply of the current.
Thereby, the current control circuit can be handled as a current source capable of controlling the output current. As a result, the current supplied to the object to be inspected can be easily controlled.

Moreover, according to this invention, a surge current generator is a surge current generator which outputs an electric current to to-be-inspected object. In this surge current generator, a plurality of current control circuits are mainly operated by a power supply unit, and each of the divided currents is controlled to operate as a unit current source. The selection control circuit is provided corresponding to the current control circuit, and controls supply and interruption of the current by synchronizing the selected current control circuit. The current adder adds the currents output from the current control circuit.
Thereby, the current control circuit can be handled as a current source capable of controlling the output current. A plurality of current control circuits can be combined, and the current output unit can add and output the respective currents to be output. Further, since the current control circuit can synchronize the generation timing of the output current, the added current can be concentrated at a specific time. Thereby, it is possible to generate a large current that combines the current capacities output by the individual current control circuits.

According to the invention, in the above invention, the current control circuit is formed of an active element that controls the shunted current and a control signal generation unit. The control signal generation unit includes a first resistor that divides an input voltage, a second resistor connected in series to the first resistor, and a discharge control capacitor element connected in parallel to the second resistor. Consists of including.
As a result, the current generated by each current control circuit can suppress the current value due to the circuit being dispersed. Therefore, it is possible to reduce the capacity of the discharge control capacitive element that is charged in order to cope with the current surge waveform in which the application time becomes long, and the structure can be easily configured.

Further, according to the present invention, in the above invention, the polarity switching unit switches the polarity of the current supplied to the object to be inspected.
As a result, even if the current control circuit has a unipolar configuration, the direction of the output current can be easily reversed by providing the polarity switching unit. For this reason, a bipolar test can be performed without changing the connection of the inspection object.

It is a block diagram which shows the surge current generator by this embodiment. It is a block diagram which shows the surge current generator in the conventional embodiment.

Hereinafter, a surge current generator according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic block diagram showing a surge current generator 100 according to the present embodiment.
The surge current generator 100 shown in this figure is a test apparatus that applies a surge current to a device under test (DUT) 90. As an example of the semiconductor device applied to the device under test (DUT) 90, a two-terminal thyristor used for a surge current protection circuit can be applied. The surge current generator 100 can control the current value of the output current even if it is a device under test (DUT) 90 that performs a switching operation.

The surge current generator 100 includes current control circuits 10-1 to 10-n, selection control circuits 20-1 to 20-n, a power supply unit 30, a control power supply unit 40, a current addition unit 50, and a polarity switching unit 60.
In the surge current generator 100, the current control circuits 10-1 to 10-n (hereinafter, collectively referred to as “current control circuit 10”) shunt the surge current applied to the object 90 to be inspected. Operates as an independent unit current source. Each of the current control circuits 10 is independently controlled, and can switch between supply and interruption of the output surge current. The output surge current is a current determined by a current value corresponding to the control voltage generated by the internal circuit.
Each of the current control circuits 10 includes active elements 11-1 to 11-n (hereinafter referred to as “active elements 11” collectively) and control signal generators 12-1 to 12-n (hereinafter collectively illustrated). And a current limiting resistor 16-1 to 16-n (hereinafter, collectively referred to as a “current limiting resistor 16”).

  The active element 11 controls energization of a current divided for each current control circuit 10. When the energization current is controlled by the current control circuit 10 in the active element 11, the current supplied from the power supply 30 is supplied to the inspection target 90. For example, a current control element such as a transistor (bipolar transistor), a FET (field effect transistor), or an IGBT (insulated gate bipolar transistor) can be applied to the active element 11. When the active element 11 is an FET, the P terminal of the active element 11 corresponds to the drain, the O terminal corresponds to the source, and the C terminal corresponds to the gate. Hereinafter, a case where the active element 11 is an FET will be described as a representative.

The control signal generator 12 includes a resistor 13 (first resistor) that divides an input voltage, a resistor 14 (second resistor) connected in series to the resistor 13, and a resistor 14 (second resistor). And a capacitor 15 (discharge control capacitance element) connected in parallel. When a control voltage is applied to the resistor 13, the control signal generator 12 generates an energization peak current control voltage of the active element 11 based on a voltage division ratio between the resistor 13 and the resistor 14. Further, a discharge current control voltage is generated by a discharge time constant determined by the resistor 14 and the capacitor 15. The generated energization peak current control voltage and the discharge current waveform control voltage are applied to the active element 11 to control the energization current waveform of the active element 11.
The current limiting resistor 16 is provided corresponding to the active element 11, and an output current is controlled in accordance with a voltage drop caused by a current flowing through each active element 11.

  The power supply terminals Tb10p-1 to Tb10p-n (hereinafter, collectively referred to as "power supply terminal Tb10p") of the current control circuit 10 are connected to the P terminal (drain) of the active element 11, and the output terminals Tb10o-1 to Tb10o-1. Tb10o-n (hereinafter, collectively referred to as "output terminal Tb10o") is connected via a current limiting resistor 16 to which an O terminal (source) of the active element 11 is connected in series, and is connected to a control terminal Tb10c-1. To Tb10c-n (hereinafter referred to as "control terminal Tb10c" when collectively shown) are connected to the C terminal (gate) of the active element 11 via the control signal generator 12.

Selection control circuits 20-1 to 20-n (hereinafter, collectively referred to as “selection control circuit 20”) are provided corresponding to each current control circuit 10, and each switch SW1- outputs a selection signal. 1 to SW1-n (hereinafter, collectively referred to as “switch SW1”). The switch SW1 includes control power supply terminals Tb20i-1 to Tb20i-n (hereinafter referred to as “control power supply terminal Tb20i” collectively) and control signal output terminals Tb20o-1 to Tb20o-n (hereinafter collectively). Are connected to the “control signal output terminal Tb20o”) to control the connection between the control power supply terminal Tb20i and the control signal output terminal Tb20o.
The selection control circuit 20 can control the supply and interruption of the surge current output from the selected current control circuit 10. The selection control circuit 20 can control the timing for controlling the current control circuit 10 in synchronization. It is possible to control to generate a current surge that rises sharply by adding and applying output currents so as to be supplied at the same timing. The selection control circuit 20 can be controlled by operating the switch SW1, and the switch SW1 may be controlled by a control signal from a control unit (not shown).

The power supply unit 30 is a current source that supplies a surge current to be applied to the inspection target 90. The power supply unit 30 includes a voltage source 31 (Vp) and a capacitor 32 (Cp) connected in parallel to the voltage source 31. The negative electrode of the voltage source 31 and one end of the capacitor 32 are connected to the reference potential connection terminal, and the positive electrode of the voltage source 31 and the other end of the capacitor 32 are connected to the output terminal. The capacitor 32 is always charged by the power supply 31 in order to cope with an output current that changes abruptly, and compensates for the current at the time of current output. Thus, the capacitor 32 has an effect of reducing the output impedance of the power supply unit 30.
The control power supply unit 40 supplies control power necessary for the operation of the current control circuit 10 and the selection control circuit 20. The voltage waveform is converted by the current control circuit 10 in accordance with the voltage supplied from the control power supply unit 40, and a current corresponding to the converted voltage waveform is output from the current control circuit 10. In the control power supply unit 40, the output terminal Tb40p indicates the positive electrode, the output terminal Tb40c indicates the negative electrode, and outputs the voltage Vref.

The current adder 50 adds the currents output from the current control circuit 10 and outputs a combined current. The current adder 50 includes input terminals Tb50i-1 to Tb50i-n (hereinafter, collectively referred to as “input terminal Tb50i”) provided in correspondence with the current control circuit 10, and an output terminal Tb50o. Between the input terminals Tb50i-2 to Tb50i-n and the output terminal Tb50o, diodes 51-2 to 51-n (hereinafter, collectively referred to as “diode 51”) are provided, and the cathodes are connected in common. Further, only the input terminal Tb50i-1 is directly connected to the output terminal Tb50o.
By combining the current adding unit 50 with the polarity switching unit 60, the direction of the current can be unidirectional. The current adding unit 50 can prevent backflow by providing a switching element such as a diode in connection with the current control circuit 10. The current adder 50 includes a system for adding without using a diode in a system connected to one current control circuit 10. This connection makes it possible to share the control power supply unit 40 that operates the current control circuit 10 and the like.

The polarity switching unit 60 switches the polarity of the current supplied to the inspection target 90. The polarity switching unit 60 constitutes a bridge circuit with four switches 61 to 64. The polarity switching unit 60 sets the opposing switch 61 (SW2a) and switch 63 (SW2b), and the switch 62 (SW3a) and switch 64 (SW3b) as a set, and makes one of each set conductive and the other cut off. Switch the continuity of the bridge circuit. In the polarity switching unit 60, one end of the switch 61 (SW2a) and the switch 62 (SW3a) is connected to the input terminal Tb60i, and one end of the switch 63 (SW2b) and the switch 64 (SW3b) is connected to the ground terminal Tb60g.
The output terminal Tb60o-1 is connected to the other end of the switch 61 (SW2a) and the switch 64 (SW3b), and the output terminal Tb60o-2 is connected to one end of the switch 62 (SW3a) switch 63 (SW2b).
The polarity switching unit 60 can switch the direction of the current by switching the switches 61 to 64.

Next, a connection example of the surge current generator 100 having the above-described configuration will be described.
The Tb 10p of the current control circuit 10 is connected to the output terminal of the power supply unit 30 whose reference potential connection terminal is connected to the reference potential. The output terminal Tb40P of the control power supply unit 40 is connected to the control power supply terminal Tb20i of the selection control circuit 20, and the output terminal Tb40c is connected to the output terminal Tb10o-1 of the current control circuit 10. The control signal output terminal Tb20o of the selection control circuit 20 is connected to the control terminal Tb10c of the corresponding current control circuit 10, respectively. The output terminal Tb10o of the current control circuit 10 is connected to the input terminal Tb50i of the current adder 50, respectively. The output terminal Tb50o of the current adding unit 50 is connected to the input terminal Tb60i of the polarity switching unit 60, and the ground terminal Tb60g is connected to the reference potential terminal. A test target (DUT) 90 is connected between the output terminals Tb60o-1 and Tb60o-2 of the polarity switching unit 60.

Subsequently, the operation of the surge current generator 100 will be described.
First, the mechanism of current control in the surge current generator 100 will be described by taking as an example the case of control by a pair of current control circuit 10-1 and selection control circuit 20-1. Except as otherwise described in this description, the description will be made with reference to the potential of the negative electrode of the control power supply 40.
By setting the switch SW1-1 of the selection control circuit 20-1 to the on (conducting) state, the voltage Vref that changes stepwise is applied to the control input terminal Tb10c-1 of the current control circuit 10-1. The current control circuit 10-1 receives the voltage Vref and controls the output current I1. The current I1 can be regarded as an excessive response due to a step input of the voltage Vref.
The input voltage Vref is divided into the voltage Vc by the resistor 13 and the resistor 14, but the voltage Vc transitions with a first-order lag response characteristic due to the presence of the capacitor C15. That is, the voltage Vc becomes the above-described energization peak current control voltage and the discharge current waveform control voltage. The active element 11 to which the voltage Vc is applied as the control voltage becomes conductive when a voltage equal to or higher than a predetermined threshold is applied to the C terminal, and causes the current I1 to flow into the limiting resistor 16-1. In the limiting resistor 16-1, a voltage drop of (Rs × I1) occurs due to the current I1, and the potential of the O terminal of the active element rises according to the voltage drop. The control voltage applied between the C terminal and the O terminal of the active element 11-1 is lowered by the increase of the voltage of the O terminal of the active element 11-1. That is, when an FET is applied to the active element 11-1, it functions as a circuit configuration of a source follower. The above relationship shows that the current output from the active element 11-1 can be set.

Since the current output from the active element 11-1 circulates through the selection control circuit 20-1, the impedance of the C terminal of the active element 11-1 is high. Will return. The remaining current is a current that flows in a closed circuit connected to the current control circuit 10 via the current adding unit 50, the polarity switching unit 60, the device under test (DUT) 90, and the power supply unit 30. Thereby, the surge current generator 100 can apply the current set as the output current of the active element 11-1 to the inspection target (DUT) 90.
Even if the device under test (DUT) 90 is a semiconductor device that performs a switching operation such as a thyristor, it is possible to follow the current value output according to the voltage Vc that controls the active device 11-1. For example, in order to apply a current surge having a rise time of 10 microseconds and a half width of 1000 microseconds (10 × 1000 microseconds) to the device under test (DUT) 90, a control voltage that satisfies the above time condition for the voltage Vc It is possible to generate a predetermined current surge by controlling by the above.

A mechanism of current addition in the surge current generator 100 is shown.
It is assumed that the current value that can be supplied by each current control circuit 10 and the selection control circuit 20 is set to the same value (for example, 10 A (ampere)). The current that can be applied to the device under test (DUT) 90 is the sum of the currents supplied by the current control circuit 10 and the selection control circuit 20 connected in parallel. That is, in the current control circuit 10 and the selection control circuit 20 set to the same current value I, the current output from the surge current generating device 100 can be changed according to the number n of sets to be operated. Becomes (I × n).

As an example, a combination of the one set of current control circuit 10-1 and selection control circuit 20-1 shown above and the other set of current control circuit 10-2 and selection control circuit 20-2 is used. Will be described in more detail.
The currents output from the power supply unit 30 and shunted into the respective groups and controlled in current value are added by the current addition unit 50 and applied to the device under test (DUT) 90 via the polarity switching unit 60. Return to section 30.

The current control in the current control circuit 10-2 and the selection control circuit 20-2 is controlled similarly to the current control in the current control circuit 10-1 and the selection control circuit 20-1. The difference is that in the circuit using the current control circuit 10-2 and the selection control circuit 20-2, the output terminal Tb10o-2 of the current control circuit 10-2 is connected to the control power supply via the diode 51-2 in the current adder 50. Connected to the negative electrode of the portion 40.
The current output from the active element 11-2 is a weak current required for current control because the impedance of the C terminal of the active element 11-2 is high in the circuit circulating through the selection control circuit 20-2. Will return. The remaining current is a current that flows in a closed circuit connected to the current control circuit 10 via the current adder 50, the polarity switch 60, the device under test (DUT) 90, and the power supply unit 30. Thereby, the current set as the output current of the surge current generator 100 and the active element 11-2 can be applied to the device under test (DUT) 90.

  Although the example of the form which combined 2 sets was shown above, if the several current control circuit 10 and the selection control circuit 20 are used similarly, the electric current which each outputs will be carried out by the diode 51 provided in the current addition part 50. Can be added. When the current is output from the current control circuit 10 and the selection control circuit 20, the diode 51 adds the output currents, and does not operate the current control circuit 10 and the selection control circuit 20 and does not output the current. The current flowing into the current control circuit 10 that does not output current is cut off. Accordingly, the diode 51 can protect the circuit by preventing a large current from flowing into the current control circuit 10.

  As described above, the plurality of selection control circuits 20 control the plurality of current control circuits 10 in the same phase, and thereby have a surge current having a current value obtained by adding the current values output from the individual current control circuits 10. Can be generated.

  The surge current generator of the present invention corresponds to the surge current generator 100. The power supply unit of the present invention corresponds to the power supply unit 30. The current control circuit of the present invention corresponds to the current control circuit 10 (10-1, 10-2 to 10-n). The selection control circuit of the present invention corresponds to the selection control circuit 20 (20-1, 20-2 to 20-n). Further, the current adder of the present invention corresponds to the current adder 50. The active element of the present invention corresponds to the active element 11 (11-1, 11-2 to 11-n). The control signal generation unit of the present invention corresponds to the control signal generation unit 12 (12-1, 12-2 to 12-n). The polarity switching unit of the present invention corresponds to the polarity switching unit 60.

  The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention. In the current control circuit 10 in the surge current generator 100 of the present invention, the peripheral circuit of the active element 11 is changed according to the applied semiconductor device, and the number of components and the current capacity are not specified.

DESCRIPTION OF SYMBOLS 100 Surge current generator 10-1, 10-2, 10-n Current control circuit 11-1, 11-2, 11-n Active element 12-1, 12-2, 12-n
13, 14 Resistor 15 Capacitor 16-1, 16-2, 16-n Current limiting resistor 1-1, 1-2, 1-n
20-1, 20-2, 20-n selection control circuit SW1-1, SW1-2, SW1-n switch 30 power supply unit 31 power supply 32 capacitor 40 control power supply unit 50 current addition unit 51-2, 51-n diode 60 Polarity switching unit 61, 62, 63, 64 Switch SW2a, SW2b, SW3a, SW3b
90 inspection target (DUT)

Claims (4)

A surge current generator that outputs current to an object to be inspected,
A power supply for outputting the current;
A current control circuit that controls the current and operates as a unit current source;
A selection control circuit for controlling supply of the current output from the current control circuit;
A polarity switching section for switching the polarity of the current,
The current control circuit performs constant current control of the current so as to have a predetermined current value according to a voltage determined with reference to a reference potential, and causes the current of the current value to flow through the inspection target. wherein one end is grounded according to a voltage applied to the both ends of the object to be inspected, the surge current generator, wherein the reference potential relative to the potential of the ground varies. A surge current generator that outputs current to an object to be inspected,
A power supply for outputting the current;
A plurality of current control circuits that operate as unit current sources by controlling currents shunted from currents output by the power supply unit;
A plurality of selection control circuits which are provided corresponding to the current control circuits and which control the supply and interruption of the current by synchronizing the selected current control circuits;
A current adder for adding the currents output from the current control circuit;
With
The current control circuit performs constant current control of the current so as to have a predetermined current value according to a voltage determined with reference to a reference potential, and causes the current of the current value to flow through the inspection target. wherein one end is grounded according to a voltage applied to the both ends of the object to be inspected, the surge current generator, wherein the reference potential relative to the potential of the ground varies. The current control circuit is
An active element for controlling a current shunted from a current output by the power supply unit;
A voltage based on a reference potential of the current control circuit is input, a first resistor that divides the input voltage, a second resistor connected in series to the first resistor, and the second A control signal generation unit configured to include a discharge control capacitance element connected in parallel to the resistance of
With
The surge current generator according to claim 1, wherein the active element controls a current that flows according to a voltage obtained by dividing the input voltage. The surge current generator according to claim 2, further comprising: a polarity switching unit that switches a polarity of a current supplied to the inspection target.

Images