JP2948633B2 - Method for measuring voltage of semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] Regarding a voltage measuring method for a semiconductor device, a semiconductor capable of easily and highly accurately measuring a minute voltage change of an output voltage of a semiconductor device to be measured using an inexpensive and highly versatile semiconductor tester. A first variable power supply capable of changing a value of a voltage supplied to a power supply terminal of a semiconductor device to be measured, and a method of measuring a voltage supplied to a ground terminal of the semiconductor device to be measured. Measurement using a semiconductor tester including a second variable power supply whose value can be changed, an amplifier for amplifying the output voltage of the semiconductor device to be measured based on the input signal, and a voltmeter for measuring the amplification result by the amplifier When measuring the output voltage of the semiconductor device, the voltage value of both variable power supplies is increased or decreased so that the voltage difference between the first and second variable power supplies is maintained at a predetermined value. The output voltage was set near the ground level of the voltmeter.

The present invention relates to a method for measuring a voltage of a semiconductor device.

In recent semiconductor devices, for example, digital-analog converters (hereinafter, referred to as D / A converters) and the like, there is a demand for improved accuracy, and it is necessary to measure a minute voltage change in a voltage measurement test. It is desired that this voltage measurement test can be easily and accurately performed by a low-cost and highly versatile semiconductor tester.

2. Description of the Related Art Conventionally, a semiconductor tester for measuring an output voltage of a semiconductor device includes first and second variable power supplies for supplying a predetermined operating voltage to the semiconductor device to be measured, And a voltmeter for measuring the output voltage. Then, when voltage values of the first and second variable power supplies are set so that an operation voltage required for the semiconductor device to be measured is obtained at the time of voltage measurement, those voltage values are fixed.

Then, in order to measure a minute voltage change of the output voltage of the semiconductor device to be measured, a semiconductor tester provided with a voltmeter having a high resolution, that is, a high measurement accuracy and a wide measurement range may be used. It will be very expensive and customized.

In addition, inexpensive and versatile semiconductor testers use a voltmeter that has a limited resolution, that is, a measurement accuracy, and also has a limited measurement range. It cannot be measured in the following cases. For this reason, when trying to measure a small voltage change of a semiconductor device under test using this inexpensive and highly versatile semiconductor tester, an amplifier that amplifies the output voltage of the semiconductor device under test beyond the resolution of the voltmeter And the voltage amplified by the amplifier is measured by a voltmeter.

[Problems to be Solved by the Invention] However, since the voltage values of the first and second variable power supplies are fixed after setting, the output voltage of the semiconductor device under test and the amplifier However, when the voltage is simply amplified, the amplified voltage exceeds the measurement range of the voltmeter, and there is a problem that the measurement cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a semiconductor device capable of easily and accurately measuring a minute voltage change of an output voltage of a semiconductor device to be measured by using an inexpensive and versatile semiconductor tester. It is an object of the present invention to provide a method for measuring the voltage of a device.

[Means for Solving the Problems] In the present invention, as shown in FIG. 1, a first variable power supply E1 supplies a voltage to a power supply terminal VDD of a semiconductor device under test 1,
The variable power supply E2 supplies a voltage to the ground terminal VSS, and its voltage value can be changed. Then, the voltage values of the variable power supplies E1 and E2 are increased or decreased so that the potential difference between the variable power supplies E1 and E2 is maintained at a predetermined value, and the output voltage of the semiconductor device 1 to be measured is changed to the ground level of the voltmeter 3. In the vicinity, the output voltage is amplified by the amplifier 2 and then measured by the voltmeter 3.

[Operation] Since the output voltage of the semiconductor device under test 1 is near the ground level of the voltmeter 3 by adjusting the voltage values of the first and second variable power supplies E1 and E2, the amplifier 2 amplifies the output voltage. The voltage falls within the measurement range of the voltmeter 3. Then, even if there is a small change in the output voltage while the voltage values of the first and second variable power supplies E1 and E2 are maintained at the adjusted values, the amplified voltage by the amplifier 2 falls within the measurement range of the voltmeter 3.
At this time, even if the minute change of the output voltage is lower than the resolution of the voltmeter 3, the output voltage is amplified by the amplifier 2 to the resolution or higher. Accordingly, a difference between the amplified voltage of the output voltage after the change and the amplified voltage of the output voltage before the change is obtained, and the difference is divided by the amplification factor of the amplifier 2, whereby a minute change equal to or less than the resolution of the voltmeter 3 is obtained.

Example An example of the present invention will be described below with reference to FIGS.

Note that the same components as those in FIG. 1 will be described with the same reference numerals.

FIG. 2 shows an example of a semiconductor tester. A digital-to-analog converter (hereinafter D / A)
The A converter 10 is based on n-bit digital input signals D0 to Dn-1 in an output voltage range VF determined by the voltage applied to the power supply terminal VDD and the voltage applied to the ground terminal VSS. The output voltage VO of the output value is output.

The first variable power supply E1 supplies a voltage to the power supply terminal VDD of the D / A converter 10, and the second variable power supply E2 supplies a voltage to the ground terminal VSS. The voltage values of the first and second variable power supplies E1 and E2 can be arbitrarily changed by manually operating a volume (not shown). The first variable power supply E1 has a level of the ground GND, that is, 0 V or more. The voltage value can be set, and the second variable power supply E2 can set a voltage value of 0 V or less.

The amplifier 11 includes an operational amplifier 12 and a pair of voltage dividing resistors R provided in series between the output terminal of the amplifier 12 and the ground GND.
The non-inverting input terminal of the operational amplifier 12 is connected to the D / A converter 10 to receive the output voltage VO of the converter 10, and the inverting input terminal is connected between the voltage dividing resistors R1 and R2. And a part of the output voltage (amplified voltage) VA is fed back. Therefore, the amplifier 11 changes the output voltage VO to α (=
Outputs amplified voltage VA multiplied by (R1 + R2) / R2).

The voltmeter 3 provided between the amplifier 11 and the ground GND comprises an analog-digital converter, and outputs the amplified voltage VA of the amplifier 11 as a digital signal. The voltmeter 3 uses an inexpensive and general-purpose voltmeter whose minimum resolution, that is, measurement accuracy is larger than the minimum resolution of the D / A converter 10.

Next, the D / A converter 1 using the semiconductor tester having the above configuration
A method of measuring the output voltage VO of 0 will be described.

For convenience of explanation, the voltmeter 3 in this embodiment has a minimum resolution of 2 mV and a measurement range of ± 10 V. D / A converter 1
0 has a resolution of 12 bits precision for inputting the digital input signals D0 to D11, and the width of the output voltage range VF, that is,
The potential difference between the power supply terminal VDD and the ground terminal VSS is assumed to be 5V. Therefore, 1 LSB (minimum resolution) of the D / A converter 10 is 1.2
It becomes 2 mV (V5 V / 2 ¹² ), and the minute voltage change of 1 LSB is less than the minimum resolution of the voltmeter 3. Further, if the resistance values of the voltage dividing resistors R1 and R2 are 9.9 kΩ and 0.1 kΩ, the amplification factor α of the amplifier 11 is
(9.9 + 0.1) /0.1=100.

Now, for example, when the digital input signals D0 to D11 change from #FFE (hexadecimal display) to #FFF (hexadecimal display),
When measuring the change in the output voltage VO of the / A converter 10, when the voltage value of the first variable power supply E1 is 5V and the voltage value of the second variable power supply E2 is 0V, the digital input signals #FFE, #FF The ideal output voltage of D / A converter 10 for FFF is 4997.6mV, 4998.8
mV, and when these are amplified by the amplifier 11, 499.76V and 4
It becomes 99.88 V, which greatly exceeds the measurement range of the voltmeter 3 ± 10 V, and the measurement becomes impossible.

Therefore, the voltage values of the first and second variable power supplies E1 and E2 are increased or decreased by the same value so that the potential difference between the two power supplies E1 and E2 is maintained at 5 V, as shown in FIG. Then, the output voltage VO of the D / A converter 10 is set to a value near the level of the ground GND.

That is, in the above case, the first and second variable power supplies E1, E2
And the variable power supply E1 is set to 0.05 V and the variable power supply E2 is set to −4.95 V so that the output voltage VO of the D / A converter 10 becomes a value near the level of the ground GND. I do. D / A converter for digital input signals #FFE, #FFF at this time
The ideal output voltage of 4 is 47.6mV and 48.8mV. Even if these are amplified by the amplifier 11, they become 4.76V and 4.88V, and the voltmeter 3
Within the measurement range of ± 10V, both output voltages can be measured.

Then, a difference between the two amplified voltages measured as described above is obtained, and the difference is divided by the amplification factor α of the amplifier 11, whereby a change voltage of 1 LSB from the digital input signal #FFE to #FFF can be obtained. That is, the two amplified voltages are 4.88 V and 4.76 V, and the difference between the two is 1.22 V. When this is divided by the amplification factor α = 100, it becomes 1.22 mV.

Thus, in this embodiment, the first and second variable power sources E
1 and E2 so that the potential difference between the two power supplies E1 and E2 becomes a predetermined value, and the output voltage VO of the D / A converter 10
Since it is set to a value near the ND level, even a semiconductor tester equipped with an inexpensive and highly versatile voltmeter 3 that has limitations in resolution and measurement range can easily change a small voltage less than the resolution of the voltmeter 3. And it can measure with high precision.

In the present embodiment, the voltage dividing resistors R1 and R2 in the amplifier 11 are fixed resistors, but one of the voltage dividing resistors R1 and R2 may be a variable resistor, and the amplification factor α may be changed. .

In this embodiment, the voltage values of the first and second variable power supplies E1 and E2 are changed by manually operating a volume control (not shown).
A switching controller for switching and controlling the voltage value of each of the variable power supplies E1 and E2 based on Dn-1 may be provided.

Further, in the present embodiment, the D / A converter 10 was implemented as the semiconductor device to be measured, but the output voltage was output within the voltage range supplied to the power supply terminal and the ground terminal, and the voltage of the power supply terminal and the ground terminal was reduced. The present invention can be applied to all semiconductor devices whose output voltage changes in synchronization with the change.

[Effects of the Invention] As described in detail above, according to the present invention, an inexpensive and highly versatile semiconductor tester can be used to easily and accurately measure a small voltage change in the output voltage of a semiconductor device under test. effective.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a block circuit diagram illustrating a semiconductor tester in one embodiment, and FIG. 3 is a diagram illustrating the operation of the embodiment. In the figure, 1 is a semiconductor device to be measured, 2 is an amplifier, 3 is a voltmeter, E1 is a first variable power supply, E2 is a second variable power supply, VDD is a power supply terminal, and VSS is a ground terminal.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01R 31/26 G01R 31/28 H01L 21/66

Claims (1)

(57) [Claims] A power supply terminal (VD) of a semiconductor device under test (1).
D) a first variable power supply (E
1), a second variable power supply (E2) capable of changing the value of the voltage supplied to the ground terminal (VSS) of the semiconductor device under test (1), and the semiconductor device under test (1) based on the input signal.
The output voltage of the semiconductor device under test (1) is measured using a semiconductor tester having an amplifier (2) for amplifying the output voltage of the semiconductor device and a voltmeter (3) for measuring the amplified voltage of the amplifier (2). At this time, the voltage value of both variable power supplies (E1, E2) is increased or decreased so that the voltage difference between the first and second variable power supplies (E1, E2) is maintained at a predetermined value, and the semiconductor device to be measured ( A method for measuring a voltage of a semiconductor device, wherein the output voltage of 1) is set near a ground level of a voltmeter (3).