JP2006133097A - Testing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a fine resistance value with simple configuration, concerning a testing device applied to measurement of a fine resistance related to, for example, an integrated circuit. <P>SOLUTION: A resistance value of a measuring object 5 is measured based on a both terminal potential difference V2 of the measuring object acquired by supplying an alternating current S1, and the resistance value is detected based on an integrated value determined by integrating measurement data D1 acquired by performing analog/digital conversion processing of the both terminal potential difference V2 in a positive period and/or a negative period of the alternating current S1. Otherwise, the resistance value is detected based on an amplitude value of a fundamental frequency component acquired by performing Fourier transform of the measurement data D1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a test apparatus and can be applied to, for example, measurement of a minute resistance related to an integrated circuit. In the present invention, the resistance value of the measurement object is measured based on the potential difference between both ends of the measurement object obtained by supplying an alternating current, and the measurement data obtained by performing the analog-digital conversion process on the potential difference between both ends is converted into a positive AC current. By detecting the resistance value based on the integral value integrated in the period and / or the negative period, or by detecting the resistance value based on the amplitude value of the fundamental frequency component obtained by Fourier transforming this measurement data A small resistance value can be measured with a simple configuration.

  2. Description of the Related Art Conventionally, a test apparatus for an integrated circuit is provided with a function of measuring a resistance value. In such a resistance value measurement, a so-called current-voltage method is generally applied. Here, the current-voltage method is a method in which a direct current is passed through a resistance to be measured and a resistance value is obtained from a voltage drop in the resistance.

  Various measures have been proposed for measuring the resistance value by such a current-voltage method, for example, in JP-A-7-55857.

  However, in the measurement of the resistance value by such a current-voltage method, when the resistance value of the measurement target is small and a large current cannot be passed through the measurement target, the voltage drop in the resistance is also small, and the measurement accuracy is remarkably deteriorated. Specifically, when the current supplied to the measurement target is 50 [μA] and the resistance value of the measurement target is 20 [mΩ], the voltage drop across the resistance is 1 [μV], and amplification that amplifies the potential difference due to this voltage drop It becomes the same level as the noise level generated in the circuit.

  For this reason, in such a case, in a conventional test apparatus, an alternating current is supplied to a measurement target, and the potential difference between both ends of the measurement target generated by the supply of the alternating current is AC amplified, and then synchronously rectified using a lock-in amplifier. By doing so, the influence of noise is avoided. Note that the measurement of the minute resistance value in such a test apparatus is, for example, the measurement of the on-resistance in a semiconductor switch incorporated in an integrated circuit.

However, in the configuration in which the resistance value is measured while avoiding the influence of noise in this way, it is necessary to provide the test device with a configuration for synchronous rectification, and accordingly, there is a problem that the configuration of the test device becomes complicated. is there.
JP-A-7-55857

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose a test apparatus capable of measuring a minute resistance value with a simple configuration.

  In order to solve such a problem, in the invention of claim 1, a power supply for supplying an alternating current to a measurement object, an alternating current amplification circuit for amplifying a potential difference between both ends of the measurement object, and the alternating current amplification circuit are applied to a test apparatus. An analog-to-digital conversion circuit that performs analog-digital conversion processing on the output signal and outputs measurement data; and a data processing circuit that processes the measurement data, wherein the alternating current is a current from a rectangular wave signal, and the data processing The circuit integrates the measurement data in a positive period and / or a negative period of the alternating current, and detects the resistance value of the measurement object based on the integration result.

  According to a second aspect of the present invention, a power supply for supplying an alternating current to a measurement target, an AC amplification circuit for amplifying a potential difference between both ends of the measurement target, and an output signal of the AC amplification circuit are applied to a test apparatus. An analog-to-digital conversion circuit that performs digital conversion processing and outputs measurement data; and a data processing circuit that processes the measurement data. The data processing circuit performs a Fourier transform on the measurement data to generate a fundamental frequency of the alternating current The amplitude value of the component is detected, and the resistance value of the measurement object is detected based on the amplitude value.

  According to a third aspect of the present invention, in the configuration of the second aspect, the AC amplifier circuit has a band-pass characteristic that allows the fundamental frequency component to selectively pass therethrough.

  The configuration according to claim 1 is applied to a test apparatus, a power source for supplying an alternating current to a measurement target, an AC amplification circuit for amplifying a potential difference between both ends of the measurement target, and an analog-digital conversion of an output signal of the AC amplification circuit An analog-to-digital conversion circuit that processes and outputs measurement data; and a data processing circuit that processes the measurement data, wherein the alternating current is a current from a rectangular wave signal, and the data processing circuit If the measurement data is integrated during a positive period and / or a negative period, and the resistance value of the measurement object is detected from the integration result, the resistance value can be measured by reducing the influence of noise by the integration process. Thus, the minute resistance value can be measured with a simple configuration.

  According to a second aspect of the present invention, a power supply for supplying an alternating current to a measurement target, an AC amplification circuit for amplifying a potential difference between both ends of the measurement target, and an output signal of the AC amplification circuit are applied to a test apparatus. An analog-to-digital conversion circuit that performs digital conversion processing and outputs measurement data; and a data processing circuit that processes the measurement data. The data processing circuit performs a Fourier transform on the measurement data to generate a fundamental frequency of the alternating current By detecting the amplitude value of the component and detecting the resistance value of the measurement object based on the amplitude value, it is possible to reduce the influence of noise by Fourier transform and measure the resistance value. Thus, it is possible to measure a minute resistance value.

  According to the configuration of claim 3, in the configuration of claim 2, the AC amplifier circuit has a band-pass characteristic that selectively allows the fundamental frequency component to pass therethrough, thereby further reducing the influence of noise. it can.

  According to the present invention, a minute resistance value can be measured with a simple configuration.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

(1) Configuration of Example FIG. 1 is a block diagram showing a configuration related to resistance value measurement of a test apparatus according to an example of the present invention. The test apparatus 1 sets an integrated circuit in a wafer state or a packaged integrated circuit as a test target, and measures input / output characteristics, resistance values, and the like.

  Here, in the test apparatus 1, the signal generator 2 is a digital audio signal generator used for measurement of input / output characteristics, and outputs a rectangular wave signal S 1 having a period P and an amplitude V 1 under the control of the central processing unit 3. The test apparatus 1 connects a reference resistor 4 in series to a resistance 5 to be measured, and supplies a rectangular wave signal S1 to a series circuit including these resistors 4 and 5. Further, the divided signal S2 divided by the series circuit of the resistors 4 and 5 is input to the amplifier circuit 6. Thus, the signal generator 2 and the resistor 4 constitute a power source that supplies an alternating current to the measurement target.

  Here, the amplifier circuit 6 is an AC amplifier circuit having a sufficient frequency band with respect to the rectangular wave signal S1, and amplifies the divided signal S2 with a sufficient gain A and outputs the amplified signal. As a result, the amplifier circuit 6 constitutes an AC amplifier circuit that amplifies a voltage drop generated in the measurement object 5 by the alternating current supplied from the power supply by the potential difference between both ends of the measurement object 5.

  The analog-to-digital conversion circuit (A / D) 7 is a so-called digitizer, which performs analog-to-digital conversion processing on the output signal of the amplifier circuit 6 and outputs the measurement data D1 as the processing result to the central processing unit 3. In this process, the analog-digital conversion circuit 7 samples the output signal of the amplifier circuit 6 by a predetermined sampling number N in the positive period and the negative period of the rectangular wave signal S1, and performs an analog-digital conversion process.

  The central processing unit 3 constitutes a controller that controls the overall operation of the test apparatus 1, switches the connection to the test object in accordance with a preset test procedure, and controls each part in response to the switching of the connection. Thus, various tests are executed according to a preset procedure. In this series of processing, when measuring the resistance value, the central processing unit 3 switches the internal connection to the configuration shown in FIG. 1 and integrates the measurement circuit so that the measurement point of the integrated circuit is the resistance 5. Set up the connection to the circuit. Further, the rectangular wave signal S1 is output from the signal generator 2 during a predetermined resistance value measurement time, and the measurement data output from the analog-digital conversion circuit 7 is input and held during this period. Further, the resistance value R5 of the resistor 5 is calculated by processing the stored measurement data.

  That is, FIG. 2 is a flowchart showing a processing procedure when measuring the resistance value of the central processing unit 3. When the central processing unit 3 starts this processing procedure, the process proceeds from step SP1 to step SP2, and the analog-digital conversion circuit 7 The measurement data D1 output from is acquired. In the subsequent step SP3, the measurement data D1 acquired in this way is averaged by measurement data sampled during the positive period of the rectangular wave signal S1 and measurement data sampled during the negative period. Integration processing is performed, thereby removing the influence of noise.

  In the subsequent step SP4, the average value of the measurement data D1 in the positive period and the average value of the measurement data D1 in the negative period are subtracted, thereby calculating the amplitude value V0 using these average values.

  Here, the amplitude value V0 is obtained by amplifying the amplitude value V2 of the divided signal S2 with the gain A of the amplifier circuit 6, so that a relationship of V2 = V0 / A is obtained. Further, assuming that the resistance values of the resistors 4 and 5 are R4 and RX, respectively, the current I flowing through the resistor 5 can be expressed by I = V1 / (R4 + RX). By solving these problems, the resistance value RX of the resistor 5 can be obtained by RX = R4 · V0 / (A · V1−V0).

  As a result, the central processing unit 3 calculates the resistance value using the amplitude value V0 calculated in step SP4 in the subsequent step SP5, and proceeds to step SP6 to end the processing procedure.

(2) Operation of Example In the above configuration, in the test apparatus 1, when measuring the resistance value, a series circuit of the reference resistor 4 and the resistance 5 to be measured is formed, and the signal is measured during the resistance value measurement time. A rectangular wave signal S1 having a period P and an amplitude V1 output from the generator 2 is supplied to this series circuit. In addition, after the potential difference between both ends of the resistor 5 in these series circuits is amplified by the AC amplifier circuit 6 with a predetermined gain A, the analog / digital conversion circuit 7 performs sampling for a predetermined number of times N in the positive and negative periods of the rectangular wave signal S1. Then, measurement data D1 is generated, and this measurement data D1 is processed by the central processing unit 3 to obtain the resistance value RX of the resistor 5.

  Therefore, in measuring the resistance value RX, the resistance value R4 of the reference resistor 4 is appropriately set with respect to the resistance value RX of the resistance 5 to be measured, and a sufficient gain is set in the amplifier circuit 6. Thus, even when the resistance value RX of the measurement target is small and a large current cannot be passed through the measurement target, the measurement data D1 can be changed with sufficient resolution in accordance with the resistance value RX. It is considered that the resistance value can be measured with accuracy.

  However, when the resistance value RX is extremely small, the influence of noise on the measurement data D1 cannot be avoided. Thus, in this embodiment, the measurement data D1 sampled during the positive period of the rectangular wave signal S1 and the measurement data D1 sampled during the negative period of the rectangular wave signal S1 are each integrated by averaging processing. Thereafter, a subtraction process is performed, whereby the influence of noise is avoided and the voltage V2 = V0 / A across the resistance 5 to be measured is detected. Further, the resistance value RX is calculated from the both-end voltage V2. As a result, in this embodiment, it is possible to measure the minute resistance by avoiding the influence of noise by the arithmetic processing of the central processing unit, and thereby the minute resistance value can be measured with a simple configuration. ing.

Thus, when removing the influence of noise by averaging in this way, noise components are randomly superimposed on the measurement data D1, and if the number of samplings used for averaging is M, the average The noise component in the value is reduced to 1 / M ^1/2 . On the other hand, in the measurement data D1, since the voltage of the signal component is constant, the measurement result does not change depending on the sampling number M used for averaging.

  Accordingly, for example, the resistance value measurement time is set to 100 [msec], the period P of the rectangular wave signal S1 is set to 1 [msec], and each sample is measured by sampling 400 samples within each positive and negative period. When creating the data D1, the number of samplings in this resistance value measurement time is 40000 samplings in the positive and negative periods, respectively. Thereby, in this case, in the measurement data D1 in the positive and negative periods, the noise signal level can be reduced to 1/200.

  In addition, in the case of calculating the resistance value by averaging the measurement data related to the terminal voltage to be measured in the positive period and the negative period, the resistance value measurement time depends on the degree of the influence of noise. The resistance measurement time can be set to the optimum value compared to the required measurement accuracy by changing the number of samplings used for averaging to various values. The value can be measured.

(3) Effects of the embodiment According to the above configuration, the rectangular wave signal is applied to the power supply for measurement, and the measurement data indicating the terminal voltage to be measured is averaged in the positive period and the negative period, respectively. By calculating the resistance value, it is possible to measure the minute resistance without providing a special configuration such as a lock-in amplifier, and thus the minute resistance value can be measured with a simple configuration.

  The test apparatus according to this embodiment processes the measurement data D1 by Fourier transform and measures the resistance value. The test apparatus according to this embodiment is configured in the same manner as the test apparatus 1 described above with respect to the first embodiment except that the processing of the measurement data D1 is different. This will be explained.

  That is, in the embodiment, the central processing unit 3 measures the resistance value RX by processing the measurement data D1 by executing the processing procedure shown in FIG. That is, when starting this processing procedure, the central processing unit 3 moves from step SP11 to step SP12, where it acquires measurement data D1 for a plurality of periods of the rectangular wave signal S1. In the subsequent step SP13, the acquired measurement data D1 is subjected to Fourier transform, and the measurement data D1 is subjected to frequency analysis. In the subsequent step SP14, the amplitude value of the fundamental frequency component corresponding to the period P of the rectangular wave signal S1 is detected from the frequency analysis result, and the detected amplitude value is converted into the amplitude value V0 of the rectangular wave signal.

  In this processing, the central processing unit 3 performs Fourier transform on the measurement data D1 by using a Fourier transform function used for measuring the input / output characteristics of the test object. In the measurement of the input / output characteristics, the signal generator 2 supplies a sine wave signal to the test object, and the response is subjected to frequency analysis to measure the distortion rate and the like.

  In the subsequent step SP15, the central processing unit 3 processes the amplitude value V0 and calculates the resistance value RX in the same manner as described above with respect to the first embodiment, and then proceeds to step SP16 to end the processing procedure.

  According to this embodiment, it is possible to effectively avoid the influence of noise by detecting the resistance value based on the amplitude value of the fundamental frequency component obtained by Fourier transform of the measurement data. The resistance value can be measured.

  In this embodiment, in the configuration of the second embodiment, a sine wave signal is output from the signal generator 2 instead of the rectangular wave signal and supplied to a series circuit of resistors 4 and 5. Thereby, the central processing unit 3 omits the process of converting the amplitude value of the fundamental frequency component detected by the Fourier transform described in the second embodiment, and measures the resistance value. In this embodiment, the configuration is the same as that of the second embodiment except that the configuration related to the sine wave signal is different.

  Even if an alternating current by a sine wave signal is supplied as in this embodiment, the same effect as in the second embodiment can be obtained.

  In this embodiment, an AC amplifier circuit having a band-pass characteristic that selectively passes a fundamental frequency component detected by Fourier transform of the measurement data D1 in the configuration of the second embodiment is applied to the amplifier circuit 6. The configuration of the amplifier circuit 6 is the same as that of the second embodiment except that the configuration of the amplifier circuit 6 is different.

  By applying an amplifying circuit having a band pass characteristic that selectively passes the fundamental frequency component as in this embodiment, it is possible to further reduce the influence of noise by this amplifying circuit, thereby more reliably, A small resistance value can be measured with a simple configuration.

  In the first embodiment, the case where the measurement data is integrated in the positive period and the negative period of the alternating current has been described. However, the present invention is not limited to this, and any of the positive period or the negative period is used. The resistance value may be detected from the integration result.

  In the first embodiment, the case where the measurement data is integrated by averaging is described. However, the present invention is not limited to this, and various integration processes such as the case where the measurement data is integrated by addition processing are widely applied. can do.

  In the above-described embodiments, the case where the present invention is applied to an integrated circuit test apparatus has been described. However, the present invention is not limited to this, and can be widely applied to various test apparatuses that measure minute resistance values. .

  The present invention relates to a test apparatus and can be applied to, for example, measurement of a minute resistance related to an integrated circuit.

1 is a block diagram illustrating a test apparatus according to an embodiment of the present invention. It is a flowchart which shows the process sequence of the central processing unit in the test apparatus of FIG. 10 is a flowchart illustrating a processing procedure of a central processing unit in a test apparatus according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Test apparatus, 2 ... Signal generator, 3 ... Central processing unit, 4, 5 ... Resistance, 6 ... Amplification circuit, 7 ... Analog-digital conversion circuit

Claims (3)

A power supply for supplying an alternating current to the object to be measured;
An AC amplifier circuit that amplifies the potential difference between both ends of the measurement object;
An analog-to-digital conversion circuit that performs analog-to-digital conversion processing on the output signal of the AC amplifier circuit and outputs measurement data; and
A data processing circuit for processing the measurement data,
The alternating current is a current by a rectangular wave signal;
The data processing circuit includes:
A test apparatus that integrates the measurement data during a positive period and / or a negative period of the alternating current, and detects a resistance value of the measurement object based on the integration result. A power supply for supplying an alternating current to the object to be measured;
An AC amplifier circuit that amplifies the potential difference between both ends of the measurement object;
An analog-to-digital conversion circuit that performs analog-to-digital conversion processing on the output signal of the AC amplifier circuit and outputs measurement data; and
A data processing circuit for processing the measurement data,
The data processing circuit includes:
A test apparatus, wherein the measurement data is subjected to Fourier transform to detect an amplitude value of a fundamental frequency component of the alternating current, and a resistance value of the measurement object is detected based on the amplitude value. The AC amplifier circuit is
The test apparatus according to claim 2, wherein the test apparatus has a band pass characteristic for selectively passing the fundamental frequency component.

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