JPS6329274A - Testing method for semiconductor element - Google Patents

Abstract

PURPOSE:To remove an ineffective component flowing to stray capacity at the time of voltage application and to measure element characteristics at a high speed by finding the difference between a voltage corresponding to a current flowing through an element and its differentiated voltage and using a current value corresponding to the difference voltage as the real positive current value of an element to be tested. CONSTITUTION:A voltage V generated by a circuit 1 is switched by a circuit 31 or 32 and supplied to the element 4 to be tested and a circuit 22 measures the current I. The circuit 31 or 32 is switched at time T1 to apply the voltage V. The current I at this time is the sum of a charging current i1 and a leak current i2. The V is divided by resistances and passed through a differential amplifier 22l, whose output V2 has a waveform similar to the charging current i1. The output V3 of an insulating amplifier 22k, on the other hand, has the same waveform as that of the current I. It is inputted to a differential amplifier 22m to obtain an output V4=V3-V2. The V3 corresponds to i1+i2, so the V4 has a waveform nearly equal to that of the i2. For the purpose, the V4 is measured and converted to obtain the i2. Consequently, element characteristics can be measured at a high speed without any decrease in measurement sensitivity.

Description

[Detailed Description of the Invention] , 3. [Field of Industrial Application] ゛~' The present invention relates to a method for testing semiconductor devices, and in particular to a method for measuring the electrical characteristics of semiconductor devices at high speed. .

[Conventional technology]

Conventionally, as a typical test method for measuring the characteristics of this type of semiconductor element, a method as shown in FIG. 4 is known.

That is, a voltage generating circuit 1, a current measuring circuit 21 that measures the current flowing from the voltage generating circuit 1, and a semiconductor device under test 4.
The voltage generating circuit 1 is configured by a switching circuit 3 that connects the voltage generating circuit 1 to the measuring terminal of the voltage generating circuit 1. A voltage generated from the voltage generation circuit 1 is applied to the semiconductor device under test 4, and the current measurement circuit 21 measures, for example, leakage current. Generally, the electrical characteristics of a semiconductor device are measured several to dozens of times on a single semiconductor device, such as by applying a voltage and measuring the current, and by applying a current and measuring the voltage. It is something. As an example of such a conventional example, Japanese Patent Laid-Open No. 51-8347
There is Publication No. 6.

[Problem that the invention seeks to solve]

FIG. 5 shows the voltage and current waveforms for one measurement. After switching the switching circuit 3 at time T1, a voltage ■ is applied from the voltage generating circuit 1, and the current is measured. At this time, the reason why the current increases immediately after applying the voltage ■ is that the charging current 11 flows through the capacitance from the voltage generation circuit 1 to the measurement terminal of the semiconductor device under test 4 and the capacitance inside the semiconductor device under test 4. Responsible. Therefore, only the leakage current 2 is measured after the time T2 during which the charging current 11 has been discharged to some extent. The switching element of the switching circuit 3 is configured with either an element with mechanical contacts or an element with electrical contacts, but the former has the disadvantage of a long operating time, and the latter has the disadvantage that there is some resistance between the contacts. Yes When the resistance between the measurement terminals of the semiconductor device under test 4 is small, the measurement accuracy decreases.

As mentioned above, in the conventional method, when measuring leakage current, the waiting time T2 until the charging current is discharged is 20 to 10
There was a drawback that it took 0ms. Furthermore, when a switching circuit using mechanical contacts is used, the switching time becomes long, and when using a switching circuit using electrical contacts, measurement accuracy is poor when the internal resistance between the measurement terminals of the semiconductor device under test is small.

Therefore, an object of the present invention is to provide a method for testing semiconductor devices that allows high-speed measurement.

[Means for solving the problem] The present invention calculates the difference between the voltage corresponding to the current flowing through the semiconductor device under test and the voltage obtained by differentiating the applied voltage, and calculates the current value corresponding to the difference voltage in the true test sample. It is characterized in that it is a current flowing through a semiconductor element.

[Effect]

In the present invention, by utilizing the fact that the voltage obtained by differentiating the voltage applied to the semiconductor device under test approximates the waveform of the charging current that flows when the voltage is applied, the reactive portion of the current flowing through the stray capacitance etc. when the voltage is applied is calculated. Remove.

〔Example〕

The present invention will be described in detail below using Examples.

FIG. 1 shows a test circuit used for measuring the characteristics of a semiconductor device according to the present invention, and parts having the same symbols as those in FIG. 4 correspond to the same parts. This circuit is voltage generating circuit 1. The current measuring circuit 221 is composed of a mechanical contact switching circuit 31, an electrical contact switching circuit 32, and a semiconductor device under test 4. In the current measuring circuit 22, 22a to 22h are fixed resistors, 22i is a variable resistor, 22j is a capacitor, 22 is a common-edge amplifier, and 22fl and 22m are amplifiers.

The voltage ■ generated by the voltage generating circuit 1 is connected to the measurement terminal of the semiconductor device under test 4 by the switching circuit 31 or the switching circuit 32, and the current ■ is measured by the current measuring circuit 22. FIG. 2 shows voltage and current waveforms at each part in FIG. 1 for measurement of one item. After switching the switching circuit 31 or the switching circuit 32 at the switching time T1, the voltage generation circuit 1 applies the voltage V. The current ■ at this time is the main charging current 1+the leakage current 12. The voltage v1 at the input end of the differential amplifier 22Q is a voltage divided by the fixed resistors 22b and 22c.

The output voltage (2) of the differential amplifier has a waveform obtained by differentiating the input voltage Vz. This voltage v2 has a waveform similar to the charging current 11. The output voltage ■8 to the isolation amplifier 22 has the same waveform as the current ■. The amplifier 22m is a differential amplifier, and its output voltage v4 is V4 = Va - V2.

Here, voltage v8 corresponds to charging current ix+leakage current 12, so 4 has a waveform approximately equal to leakage current i2.

Therefore, the leakage current 12 can be determined by measuring the differential voltage No. 7 and converting it into electric charge. It is clear that the differential voltage (4) stabilizes more quickly than the current voltage, so the waiting time T2 from applying the voltage V to measuring the voltage v4 becomes shorter. In this test method, the voltage V is several hundred seven
As described above, when the leakage current 12 is several tens of microamperes or less, the waiting time T2 can be reduced to ⅓ to 115 times compared to FIG. 5.

FIG. 3 shows an equivalent circuit for measuring the current by applying the voltage (■) to the semiconductor device under test. Assuming that the output voltage of the voltage generating circuit is V, the internal resistance of the switching circuit is R1, and the internal resistance between the measurement terminals of the semiconductor device under test is Rt, the current to be measured is
becomes I = V (Rh+2 R). Here, the internal resistance 2R of the switching circuit becomes a measurement error when measuring current/power. Therefore, in FIG. 1, when the internal resistance R between the measurement terminals of the semiconductor device under test 4 is small, a mechanical contact switching circuit 31 having a small internal resistance is used. When the internal resistance RL between the measurement terminals of the semiconductor device under test 4 is large, the internal resistance of the switching circuit is large, but the switching time is fast.
use. In this case, since the resistance RL between the measurement terminals of the semiconductor device under test is much larger than the internal resistance 2R of the switching circuit, the measurement error becomes very small. In this way, when the internal resistance between the measurement terminals of the semiconductor device under test is small, the mechanical contact switching circuit 31 is used, and when the internal resistance between the measurement terminals of the semiconductor device under test is large, the electrical contact switching circuit 31 is used. By using this method, when measuring several dozen items on one semiconductor device, the total switching time is shortened.

〔Effect of the invention〕

As described above, according to the test method of the present invention, the total time required to measure the characteristics of a semiconductor element can be shortened without reducing measurement accuracy.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the test circuit used in the test method of the present invention, Fig. 2 is a voltage/current waveform diagram of each part of the circuit, and Fig. 3 is a circuit diagram showing the test circuit used in the test method of the present invention.
FIG. 4 is a circuit diagram for current measurement, FIG. 4 is a circuit diagram showing an example of a conventional semiconductor device testing method, and FIG. 5 is a waveform diagram of each part of the circuit. 1... Voltage generation circuit, 21.22... Current measurement circuit, 3.31.32... Switching circuit, 4... Semiconductor to be measured.

Claims (1)

[Claims] 1. In a semiconductor device testing method in which a voltage is applied to the semiconductor device under test and the current flowing at that time is measured to measure the characteristics of the semiconductor device under test, a voltage equivalent to the current flowing through the semiconductor device under test is applied. Find the difference in voltage by differentiating the voltage,
A test method for semiconductor devices in which the current value corresponding to the voltage difference is the true current flowing through the semiconductor device under test.