JP2010122149A - Dc module and semiconductor-testing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein since high resistance is used as a first resistor to assure measurement accuracy in a DC module, in which the output from an output amplifier for outputting constant voltage or constant current is applied via a first switch to an object to be measured, also the voltage of the object is fed back to the output amplifier via a second switch, and the first resistor is provided between an output terminal of the output amplifier and the second switch, it takes time to charge a stray capacitance, and as a result, it takes time to change-over from a non-application mode to a current application mode. <P>SOLUTION: A third switch is connected in parallel with the first resistor, and the third switch is turned on, when change-over to short-circuit the first resistor is made. Since the stray capacitance can be charged rapidly, the time for change-over can be shortened. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a DC module that supplies a DC voltage and current to an object to be measured, and does not apply an overvoltage and an overcurrent to the object to be measured, and shortens the switching time from the non-application mode to the current application mode. The present invention relates to a DC module that can be used and a semiconductor test apparatus using the same.

  The semiconductor test apparatus is an apparatus for applying a predetermined voltage and current to a semiconductor under test using a DC module and testing the semiconductor under test. Such a DC module is required not to apply an overvoltage or overcurrent to the semiconductor under test, and to have a good settling specification for the applied voltage and current.

  FIG. 5 shows the configuration of such a DC module. In FIG. 5, the DC module 10 includes an output amplifier 11, a differential amplifier 12, a buffer amplifier 13, a selection switch 14, switches 15 and 16, and resistors R1 to R3. In order to improve the measurement accuracy, a resistor having a relatively high resistance value is selected as the resistor R2.

  Reference numeral 17 denotes an output terminal of the DC module, to which a measurement object (semiconductor under test) 20 is connected. Note that RL is the resistance of the wiring leading to the inside of the DC module 10 and the measurement object 20, Cs is the off-capacitance of the switch 15 and the stray capacitance of the wiring, and R4 is between the power supply Vdut applied to the measurement object 20 and the output terminal 17. It represents resistance.

  In the voltage application mode in which a constant voltage is applied to the measurement object 20, the switches 15 and 16 are turned on, the selection switch 14 is set to the buffer amplifier 13 side, and the voltage setting value applied to the measurement object 20 is set to the output amplifier 11. Input to the non-inverting input terminal.

  The output of the output amplifier 11 is applied to the measurement object 20 via the resistor R1 and the switch 15. Further, since the voltage applied to the measurement object 20 is fed back to the inverting input terminal of the output amplifier 11 through the resistor R3, the switch 16, the buffer amplifier 13, and the selection switch 14, regardless of the resistance R1 and the wiring resistance RL. The voltage of the voltage setting value is applied to the measurement object 20.

  In the current application mode in which a constant current is applied to the measurement object 20, the switch 15 is turned on, the selection switch 14 is set to the differential amplifier 12 side, and the current set value is input to the non-inverting input terminal of the output amplifier 11. .

  The output current of the output amplifier 11 is applied to the measurement object 20 via the resistor R1 and the switch 15. The voltage across the resistor R1 is input to the differential amplifier 12, and the output of the differential amplifier 12 is fed back to the inverting input terminal of the output amplifier 11 via the selection switch 14. Is applied.

  In order not to apply overvoltage and overcurrent to the measurement object 20, the operation procedure of the selection switch 14, the switches 15 and 16 is determined. FIG. 6 shows a procedure for switching from the non-application mode in which no voltage and current are applied to the measurement object 20 to the current application mode. In the non-application mode, both switches 15 and 16 are off.

  In step (P6-1), the selection switch 14 is set to the buffer amplifier 13 side to enter the voltage application mode. This is because the output amplifier 11 may be saturated when the current application mode is set while the switches 15 and 16 are off.

  Next, in step (P6-2), the switch 16 is turned on. The output of the output amplifier 11 is applied to the measurement object 20 through the resistors R1, R2, and R3. However, since the resistance value of the resistor R2 is high, the flowing current value is small and the measurement object 20 is destroyed. There is no.

  Next, in step (P6-3), the current setting value applied to the non-inverting input terminal of the output amplifier 11 is set to 0, and the selection switch 14 is set to the differential amplifier 12 side to enter the current application mode.

Assuming that the current flowing from the power source Vdut is Izr, the voltage V1 at the connection point between the resistor R1 and the switch 15, and the voltage at the output terminal 17 is V2, these voltages are expressed by the following equations (1) and (2). Note that the resistance values of the resistors R2 to R4 and the voltage of the power source Vdut are represented by the same symbols.
V1 = Vdut−Izr × (R4 + R3 + R2) (1)
V2 = Vdut−Izr × R4 (2)
Although the voltages V1 and V2 are different at the initial stage of the step (P6-3), the capacitor Cs is charged with Izr. Therefore, when a sufficient time elapses, both the voltages V1 and V2 become substantially equal to Vdut.

  When V1 becomes substantially equal to V2, in step (P6-4), the switch 15 is turned on to establish a path for applying a current to the measurement target 20. In the step (P6-3), the voltages V1 and V2 are substantially equal to Vdut, so that noise when the switch 15 is turned on is reduced.

Finally, a current set value is set in step (P6-5). The output current of the output amplifier 11 is applied to the measurement object 20 through the path of the resistor R1 and the switch 15. Since the resistance values of the resistors R1 and RL are small, an accurate current can be applied to the measurement object 20.
JP 2007-315829 A

  However, such a DC module does not apply overvoltage and overcurrent to the measurement target 20, but there is a problem that it takes time to switch from the non-application mode to the current application mode. This will be described with reference to FIG.

  FIG. 7A is a graph showing changes in the voltage V1, where the horizontal axis is time, the vertical axis is voltage, and 30 is a graph of the voltage V1. Step (P6-3) is started at time t1. Although the voltages V1 and V2 are different at this stage, since the switch 16 is turned on, the capacitor Cs is charged through the resistors R4, R3, and R2, and the voltage V1 gradually approaches V2. When the process proceeds to step (P6-4) and the switch 15 is turned on at time t2 when V1 sufficiently matches V2, no noise is generated.

  FIG. 7B is a graph showing changes in the voltages V1 and V2 when the time of the step (P6-3) is shortened, and 30 and 31 are graphs of the voltages V1 and V2, respectively. At time t3, the process proceeds to step (P6-4), and the switch 15 is turned on. Since V2> V1 at time t3, a large current flows through the path of the resistors R4 and RL to charge the capacitor Cs. For this reason, the voltage V2 decreases by ΔV due to the voltage drop of the resistor R4, and the measurement target 20 may be destroyed due to the noise of ΔV.

  For this reason, there is a problem in that it takes time for the step (P6-3) to take a long time and switching from the non-application mode to the current application mode takes time.

  If the resistance value of the resistor R2 is decreased, the charging current of the capacitor Cs is increased, and the time until the voltage V1 matches V2 can be shortened. However, if the resistance value of the resistor R2 is decreased, the measurement accuracy decreases, so it is unnecessarily small. It cannot be a resistance value.

  Accordingly, an object of the present invention is to provide a DC module capable of shortening the switching time from the non-application mode to the current application mode without giving an overvoltage or overcurrent to the measurement object, and a semiconductor test apparatus using the DC module. It is to provide.

In order to solve such a problem, the invention according to claim 1 of the present invention,
An output amplifier to which the set value is input;
A current measuring unit for measuring the output current of the output amplifier;
An output terminal to which an object to be measured is connected and the output of the output amplifier is input;
A first switch disposed in a path between the output amplifier and the output terminal;
A buffer amplifier to which the voltage of the output terminal is input;
A second switch disposed in a path between the output terminal and the input terminal of the buffer amplifier;
A first resistor disposed between the first switch and an input terminal of the buffer amplifier;
A third switch connected in parallel to the first resistor;
A first selection switch for selecting an output of the current measuring unit or the buffer amplifier and feeding back to the output amplifier;
Is provided. Switching time from the non-application mode to the current application mode can be shortened.

The invention according to claim 2 is the invention according to claim 1,
A second resistor is provided between the output terminal and the second switch. The measurement object can be protected.

The invention according to claim 3 is the invention according to claim 1 or claim 2,
A second selection switch that receives the output of the current measurement unit and the output of the buffer amplifier, and selects one of them to output;
A measurement terminal to which a signal selected by the second selection switch is input;
Is provided. The voltage and current applied to the measurement object can be monitored.

The invention according to claim 4
A DC module according to claim 1 is provided, and the semiconductor device under test is tested by selecting and applying a predetermined voltage or current from the DC module to the semiconductor device under test. Is. The test time can be shortened without applying an overvoltage or overcurrent to the semiconductor under test.

As is apparent from the above description, the present invention has the following effects.
According to the first, second, third, and fourth inventions, the output of the output amplifier capable of switching between the constant voltage output and the constant current output is output to the output terminal via the first switch, and the voltage of the output terminal is output. Is fed back to the output amplifier via a second switch and a buffer amplifier, and the first resistor is arranged between the output terminal of the output amplifier and the input terminal of the buffer amplifier. A third switch was placed in parallel with the resistor.

  By turning on the third switch, when switching from the non-application mode to the current application mode, the off-capacitance and wiring capacity of the switch can be rapidly charged, so the waiting time at the time of switching can be reduced. it can. Therefore, there is an effect that the switching time can be shortened without giving an overvoltage and an overcurrent to the measurement object and without deteriorating the settling characteristics.

  In addition, since the switching time can be shortened, when this DC module is used in a semiconductor test apparatus, the test time can be shortened.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a DC module according to the present invention. Note that the same reference numerals are given to the same elements as those in FIG.

  In FIG. 1, reference numeral 40 denotes a DC module, which includes an output amplifier 11, a differential amplifier 12, a buffer amplifier 13, a selection switch 14, switches 15, 16, and 41, and resistors R1 to R3.

  The resistor R1 and the differential amplifier 12 constitute a current measuring unit. The selection switch 14 corresponds to a first selection switch, the switches 15, 16, and 41 correspond to first to third switches, and the resistors R2 and R3 correspond to first and second resistors, respectively.

  The switch 41 is connected in parallel to the resistor R2. In this embodiment, a switch 41 is added to the conventional example of FIG.

  Next, the operation of this embodiment will be described based on the flowchart of FIG. This flowchart shows a procedure for switching from the non-application mode in which voltage and current are not applied to the measurement object 20 to the current application mode. In the non-application mode, the switches 15, 16, and 41 are all off.

  In FIG. 2, in the step (P2-1), the selection switch 14 is set on the buffer amplifier 13 side so as not to saturate the output amplifier 11, and the voltage application mode is set. In step (P2-2), the switch 16 is turned on to connect the output amplifier 11 and the measurement object 20 via the high resistance R2. Since the connection is made through the high resistance R2, only a small current flows. Therefore, the measuring object 20 is not destroyed.

  Next, in step (P2-3), the selection switch 14 is set to the differential amplifier side to enter the current application mode, and the switch 41 is turned on. At this time, the current setting value applied to the non-inverting input terminal of the output amplifier 11 is set to zero. Since the switch 41 is turned on, the resistor R2 is short-circuited.

The voltage V1 at the connection point between the resistor R1 and the switch 15 and the voltage V2 at the output terminal 17 are expressed by the following equations (3) and (4), where Izr is the current flowing from the power supply Vdut.
V1 = Vdut−Izr × (R3 + R4) (3)
V2 = Vdut−Izr × R4 (4)
Since the resistor R2 is short-circuited by the switch 41, the resistance value of the resistor R2 does not appear in the expression (3).

  Since the capacitor Cs is charged by the current flowing through the resistors R4 and R3 and the switches 16 and 41, the difference between the voltages V1 and V2 decreases. Since the resistor R2 having a large resistance value is short-circuited by the switch 41, a charging current larger than that of the conventional example of FIG. 5 flows, and the voltage V1 matches the voltage V2 in a short time.

  When V1 and V2 are substantially equal, in step (P2-4), the switch 41 is turned off and the switch 15 is turned on to establish a current path from the output amplifier 11 to the measurement object 20. In step (P2-5), the current set value is applied to the non-inverting input terminal of the output amplifier 11.

  FIG. 3 shows the effect of the present invention. In addition, the same code | symbol is attached | subjected to the same element as FIG. 7, and description is abbreviate | omitted. FIG. 3 is a diagram showing changes in the voltage V1 in the process (P2-3), where the horizontal axis represents time and the vertical axis represents voltage.

  A solid line 50 is a graph showing a change in the voltage V1. The process (P2-3) is started at time t5, and the switch 41 is turned on. Since the resistor R2 is short-circuited by the switch 41, the capacitor Cs is charged by the power source Vdut via the resistors R4 and R3.

For this reason, the voltage V1 becomes substantially equal to V2 at time t6. The time T1 when (V2-V1) becomes 1/1000 of the initial value is expressed by the following equation (5). Note that the capacitance value of the capacitor Cs and the resistance values of the resistors R3 and R4 are denoted by the same reference numerals.
T1 = 7 × Cs × (R4 + R3) (5)

The alternate long and short dash line 30 is a graph showing a change in the voltage V1 in the DC module of FIG. 5, and V1 becomes substantially equal to V2 at time t7. The time T2 when (V2-V1) becomes 1/1000 of the initial value is expressed by the following equation (6). R2 is the resistance value of the resistor R2.
T2 = 7 × Cs × (R2 + R3 + R4) (6)

  In order to increase the measurement accuracy, the resistance value of the resistor R2 is selected to be considerably larger than that of the resistors R3 and R4. Therefore, T1 << T2, and the switching time to the current application mode can be greatly shortened.

  The resistor R3 is a resistor for protection and may not be in operation.

  Before applying a voltage to the measurement object 20, it may be necessary to check the voltage (V1) applied to the measurement object 20 in the non-application mode. The embodiment in FIG. 1 is effective in such a case because the time until the voltage V1 is stabilized can be shortened.

  In order to confirm the voltage V1, the switch 16 is turned on, and then the switch 41 is turned on. When the voltage V1 is stabilized, this voltage is measured, and the switch 41 may be turned off in order to reduce the leakage current. In this case, the waiting time can be shortened.

  FIG. 4 shows the configuration of a DC module that can monitor the voltage and current applied to the measurement object 20. In addition, the same code | symbol is attached | subjected to the same element as FIG. 1, and description is abbreviate | omitted.

  In FIG. 4, 60 is a DC module, which includes an output amplifier 11, a differential amplifier 12, a buffer amplifier 13, selection switches 14 and 61, resistors R1 to R3, switches 15, 16, and 41, an output terminal 17, and a measurement terminal 62. Composed. In this embodiment, a selection switch 61 and a measurement terminal 62 are added to the embodiment shown in FIG. The selection switch 61 corresponds to a second selection switch.

  When the selection switch 61 is set to the buffer amplifier 13 side, the voltage at the output terminal 17 can be monitored at the measurement terminal. Further, when the selection switch 61 is set to the differential amplifier 12 side, the current value applied to the measurement target 20 can be monitored.

  By setting the selection switch 61 to the buffer amplifier 13 side in the voltage application mode and the selection switch 61 to the differential amplifier 12 side in the current application mode, the voltage and current to be applied to the measurement object 20 at the measurement terminal 62 Can be monitored.

It is a block diagram which shows one Example of this invention. It is a flowchart for demonstrating operation | movement of this invention. It is a characteristic view for demonstrating operation | movement of this invention. It is a block diagram which shows the other Example of this invention. It is a block diagram of the conventional DC module. It is a flowchart for demonstrating operation | movement of the conventional DC module. It is a characteristic view for demonstrating operation | movement of the conventional DC module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Output amplifier 12 Differential amplifier 13 Buffer amplifier 14, 61 Selection switch 15, 16, 41 Switch 17 Output terminal 20 Measuring object 40, 60 DC module 62 Measurement terminal R1-R4 Resistance

Claims (4)

An output amplifier to which the set value is input;
A current measuring unit for measuring the output current of the output amplifier;
An output terminal to which an object to be measured is connected and the output of the output amplifier is input;
A first switch disposed in a path between the output amplifier and the output terminal;
A buffer amplifier to which the voltage of the output terminal is input;
A second switch disposed in a path between the output terminal and the input terminal of the buffer amplifier;
A first resistor disposed between the first switch and an input terminal of the buffer amplifier;
A third switch connected in parallel to the first resistor;
A first selection switch for selecting an output of the current measuring unit or the buffer amplifier and feeding back to the output amplifier;
A DC module comprising:   2. The DC module according to claim 1, further comprising a second resistor disposed between the output terminal and the second switch. A second selection switch that receives the output of the current measurement unit and the output of the buffer amplifier, and selects one of them to output;
A measurement terminal to which a signal selected by the second selection switch is input;
The DC module according to claim 1, further comprising:   A semiconductor test apparatus comprising the DC module according to claim 1 and testing the semiconductor under test by selecting and applying a predetermined voltage or current from the DC module to the semiconductor under test. .

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