Measurement circuit and measurement system using the same

Abstract

To provide a measurement circuit capable of accurately measuring a fine current in a small space even in combination with an inspection device having a lower accuracy in measuring a current and also capable of performing detection of a failure and acquisition of a current correction value by the inspection device.SOLUTION: A measurement circuit 100 includes: an operational amplifier 101 for forming a voltage follower to output a voltage equal to a voltage signal from an inspection device 110 to a measurement terminal 100d; a current sensing resistance 102 between an output terminal of the operational amplifier 101 and the measurement terminal 100d; an instrumentation differential amplifier 103 for amplifying a difference voltage by input terminals connected to both ends of the current sensing resistance 102 so as to output the voltage to the inspection device 110; and an operation confirmation resistance 104 where one end is connected between an input terminal of the operational amplifier 101 forming a feedback loop of the voltage follower and the current sensing resistance 102 and the other end is connected to an operation confirmation terminal 100c to be an opening state or a grounding state by the inspection device 110.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a measurement circuit and a measurement system using the same. [Background technology]

[0002] In recent years, in order to enable battery-driven devices such as wearable devices and mobile devices to operate for a long period of time, the current consumption of electronic components mounted on these devices has been reduced.

[0003] Electrical testing of semiconductor devices, which are electronic components, requires measurement accuracy on the order of nA, and conventional semiconductor testing equipment may not be able to measure the current accurately enough. For this reason, various methods and devices for measuring minute currents have been proposed.

[0004] For example, a method has been proposed in which the leakage current value is measured when the object being measured is not electrically connected, the minute current value flowing through the object being measured when the object is attached, and then the leakage current value is subtracted from the minute current value to obtain the true measured current value (see Patent Document 1).

[0005] However, it is generally difficult for conventional semiconductor inspection equipment to measure minute currents of, for example, 10 nA or less. Adding a high-precision measuring instrument to conventional semiconductor inspection equipment can sometimes make it difficult to secure the space to install the measuring instrument, or can increase the takt time due to complex communication control between the semiconductor inspection equipment and the measuring instrument. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-166950 Summary of the Invention [Problem to be solved by the invention]

[0007] One aspect of the present invention aims to provide a measurement circuit that can accurately measure minute currents in a small space even when combined with an inspection device with low current measurement accuracy, and that can detect faults and obtain current correction values ​​using the inspection device. [Means for solving the problem]

[0008] The measurement circuit in one embodiment of the present invention comprises: An additional measurement circuit that is controlled by the inspection device and performs fault detection, correction value acquisition, and minute current measurement of the device under test, an operational amplifier forming a voltage follower that outputs a voltage equal to a voltage signal input from the inspection device to a measurement terminal connected to the device under test when measuring the minute current; a current sensing resistor connected between the output terminal of the operational amplifier and the measurement terminal; an instrumentation differential amplifier having two input terminals connected to both ends of the current sensing resistor, and amplifying a differential voltage generated across the current sensing resistor and outputting the amplified voltage to the testing device; an operation check resistor having one end connected between the input terminal of the operational amplifier forming a feedback loop of the voltage follower and the current sensing resistor, and the other end connected to an operation check terminal that is set to an open state or a ground state by the inspection device; and The inspection device changes the state of the voltage signal and the operation check terminal, thereby performing the process. [Effects of the Invention]

[0009] According to one aspect of the present invention, an object is to provide a measurement circuit that can accurately measure minute currents in a small space even when combined with an inspection device with low current measurement accuracy, and that can detect faults and obtain current correction values ​​using the inspection device. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a block diagram showing the hardware configuration of a measurement circuit and a measurement system according to this embodiment. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the measurement circuit and measurement system according to this embodiment. [Figure 3] FIG. 3 is a flowchart showing the flow of a series of processes relating to minute current measurement in this embodiment. [Figure 4] FIG. 4 is a flowchart showing the flow of processing for detecting a fault in the measuring circuit in this embodiment. [Figure 5] FIG. 5 is a flowchart showing the flow of processing for obtaining a current correction value in this embodiment. [Figure 6] FIG. 6 is a flowchart showing the flow of processing for measuring minute currents in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0012] FIG. 1 is a block diagram showing the hardware configuration of a measurement circuit and a measurement system according to this embodiment. 1, measurement system 10 in this embodiment is a system that enables measurement of current values ​​on the order of nA by adding measurement circuit 100 to commercially available semiconductor inspection equipment 110, which has difficulty measuring current values ​​on the order of nA. Based on the signals and voltages input from semiconductor inspection equipment 110 to measurement circuit 100, measurement system 10 can not only measure minute currents in a DUT (Device Under Test) of a semiconductor device connected to measurement circuit 100, but also detect faults in measurement circuit 100 and obtain current correction values.

[0013] The measurement circuit 100 is an additional circuit that is controlled by the semiconductor testing equipment 110 and performs processes of fault detection, correction value acquisition, and minute current measurement of the device under test. The measurement circuit 100 includes an operational amplifier 101, a current sensing resistor 102, an instrumentation differential amplifier 103, an operation confirmation resistor 104, and a terminal control device 105. The measurement circuit 100 also includes an input terminal 100a, an output terminal 100b, an operation confirmation terminal 100c, a measurement terminal 100d, and a terminal control terminal 100e as external terminals.

[0014] The operational amplifier 101 forms a voltage follower that outputs a voltage equal to the voltage signal input to the input terminal 100a from the semiconductor testing device 110 to the measurement terminal 100d connected to the DUT when measuring a minute current.

[0015] The current sensing resistor 102 is connected between the output terminal of the operational amplifier 101 and the measurement terminal 100d in order to detect the current flowing from the measurement terminal 100d to the DUT and convert it into a voltage.

[0016] The instrumentation differential amplifier 103 has input terminals connected to both ends of the current sensing resistor 102, amplifies the differential voltage generated across the current sensing resistor 102, and outputs the amplified voltage as a voltage signal to the output terminal 100b.

[0017] The operation confirmation resistor 104 has one end connected between the input terminal of the operational amplifier 101 that forms the feedback loop of the voltage follower and the current sensing resistor 102, and the other end connected to an operation confirmation terminal 100c that is controlled to an open state or a ground state by the semiconductor inspection device 110.

[0018] Based on a terminal control signal input from the semiconductor testing device 110, the terminal control device 105 controls the operation check terminal 100c to an open state or a ground state.

[0019] In this way, the measurement circuit 100 outputs the voltage of the voltage signal input from the semiconductor inspection equipment 110 to the DUT using a voltage follower, converts the current flowing through the DUT to a voltage using the current sensing resistor 102, amplifies it using the instrumentation differential amplifier 103, and outputs it to the semiconductor inspection equipment 110.

[0020] The semiconductor testing equipment 110 includes an SMU (Source Measure Unit) 111 , a communication interface 112 , and a storage device 113 .

[0021] Using various programs stored in the memory device 113, the SMU 111 can input and output voltage signals to the measurement circuit 100 to measure the minute current of the DUT, as well as detect faults in the measurement circuit 100 and obtain correction values. The SMU 111 includes an MCU (Micro Controller Unit) 111a, a voltage / current generator 111b, and a measuring device 111c.

[0022] The MCU (Micro Controller Unit) 111a is an arithmetic and control device for controlling the voltage and current generator 111b, the measuring device 111c, and the measuring circuit 100. The voltage / current generator 111b is formed of a current source, a voltage source, and the like. The measuring device 111c is formed by a digital multimeter or the like.

[0023] The communication interface 112 receives a terminal control signal from the SMU 111 that controls the operation check terminal 100 c of the measuring circuit 100 to an open state or a ground state, and outputs the received terminal control signal to the terminal control device 105 .

[0024] The storage device 113 is, for example, a hard disk drive (HDD) that stores programs, data, and the like.

[0025] FIG. 2 is a block diagram showing the functional configuration of the measurement circuit and measurement system according to this embodiment. As shown in FIG. 2, the measuring circuit 100 has a circuit section 106 and a terminal control section 107 as its functions.

[0026] The circuit section 106 is realized by an operational amplifier 101 , a current sensing resistor 102 , an instrumentation differential amplifier 103 , and an operation confirmation resistor 104 .

[0027] The terminal control unit 107 is realized by the terminal control device 105. This terminal control unit 107 sets the operation check terminal 100c to a grounded state (a potential of 0V) in the fault detection program P1, and sets the operation check terminal 100c to an open state in the correction value acquisition program P2 and the minute current measurement program P3.

[0028] The semiconductor inspection equipment 110 has the following functions: a measurement unit 114, a communication unit 115, and a storage unit .

[0029] The measurement unit 114 is realized by the SMU 111, and includes a control unit 114a, a voltage / current generating unit 114b, and a measuring unit 114c.

[0030] The control unit 114a is realized by the MCU 111a and controls the entire measurement system 10. Using various programs stored in the memory unit 116, the control unit 114a can input and output voltage signals to and from the measurement circuit 100 to measure minute currents in the DUT, detect faults in the measurement circuit 100, and obtain correction values. The operation of these control units 114a will be described later in the description of the processing of the various programs shown in FIGS.

[0031] The voltage / current generating unit 114b is realized by the voltage / current generator 111b. This voltage / current generating unit 114b can change the potential of the operation check terminal 100c and input a voltage signal of a predetermined voltage to the input terminal 100a, according to instructions from the control unit 114a.

[0032] The measuring unit 114c is realized by the measuring device 111c. The measuring unit 114c obtains a current value from a voltage signal output from the output terminal 100b of the circuit unit .

[0033] The communication unit 115 is realized by the communication interface 112 .

[0034] The storage unit 116 stores an automatic measurement program P0, a minute current measurement program P3, a correction value acquisition program P2, and a failure detection program P1.

[0035] In the automatic measurement program P0, the control unit 114a processes the fault detection program P1, the correction value acquisition program P2, and the minute current measurement program P3 in that order, and sequentially measures the currents of multiple DUTs to determine whether each DUT is good or bad.

[0036] In the failure detection program P1, the control unit 114a performs processing to detect a failure in the measuring circuit 100. Specifically, when the fault detection program P1 is executed, the control unit 114a sets the operation check terminal 100c to a potential of 0V, and then inputs a voltage signal to the input terminal 100a to pass a current through the current sensing resistor 102. The measurement circuit 100 outputs a voltage signal obtained by amplifying the differential voltage generated across the current sensing resistor 102 with the instrumentation differential amplifier 103 set to a gain of G to the measurement unit 114c. The control unit 114a instructs the measurement unit 114c to measure the voltage signal from the measurement circuit 100, calculates the current flowing through the current sensing resistor 102, which has a known resistance value, and determines whether the calculated current matches the intended current, thereby detecting a fault in the measurement circuit 100.

[0037] In the correction value acquisition program P2, the control unit 114a performs processing to acquire the correction values. Specifically, when the correction value acquisition program P2 is executed, the control unit 114a inputs a terminal control signal to the terminal control unit 107 to open the operation check terminal 100c, inputs a voltage signal to the input terminal 100a to generate a predetermined voltage at the measurement terminal 100d, and causes a leakage current to flow through the current sensing resistor 102. The measurement circuit 100 outputs a voltage signal generated by amplifying the differential voltage generated across the current sensing resistor 102 using the instrumentation differential amplifier 103, which is set to a gain of G, to the measurement unit 114c. The control unit 114a instructs the measurement unit 114c to measure the voltage signal from the measurement circuit 100, calculates the leakage current flowing through the current sensing resistor 102, whose resistance value is known, and acquires the calculated leakage current as a correction value.

[0038] In the minute current measurement program P3, the control unit 114a performs processing to measure the minute current of the DUT. Specifically, when the minute current measurement program P3 is executed, the control unit 114a connects the measurement terminal 100d to the DUT, inputs a voltage signal to the input terminal 100a to generate a predetermined voltage at the measurement terminal 100d, and causes a current to flow through the current sensing resistor 102. The measurement circuit 100 amplifies the differential voltage generated across the current sensing resistor 102 using the instrumentation differential amplifier 103, which is set to a gain of G, and outputs the amplified voltage signal to the measurement unit 114c. The control unit 114a instructs the measurement unit 114c to measure the voltage signal from the measurement circuit 100, calculates the current flowing through the current sensing resistor 102, whose resistance value is known, and acquires the calculated current as the current value of the DUT. The control unit 114a corrects the acquired current value of the DUT using the correction value acquired by the correction value acquisition program P2 to obtain a "corrected current value."

[0039] Here, a series of processes relating to minute current measurement performed by the measurement system 10 will be described with reference to the flowchart shown in FIG. 3 and FIGS.

[0040] First, in response to a user instruction, the control unit 114a reads the automatic measurement program P0 from the storage unit 116. Then, as shown in Fig. 3, the control unit 114a checks whether the measurement circuit 100 is operating normally using the fault detection program P1 (step S01), and obtains a current correction value using the correction value acquisition program P2 (step S02). The detailed processing of steps S01 and S02 will be described later.

[0041] The control unit 114a measures the current value of the DUT using the minute current measurement program P3, and corrects the current value using the correction value acquired in step S02 (step S03). The detailed process of step S03 will be described later.

[0042] The control unit 114a determines whether the "corrected current value" is within the test standard (step S04), and if it determines that the corrected current value is within the test standard, it determines that the DUT is good (step S05), and if it determines that the corrected current value is not within the test standard, it determines that the DUT is bad (step S06).

[0043] The control unit 114a determines whether or not the next DUT exists (step S07), and if it determines that the next DUT exists, returns the process to step S03, and if it determines that the next DUT does not exist, ends the process.

[0044] In this way, the control unit 114a reads out from the storage unit 123 and executes the automatic measurement program P0 that uses the fault detection program P1, the correction value acquisition program P2, and the minute current measurement program P3, thereby performing a series of processes related to minute current measurement.

[0045] Next, the operation of the failure detection program P1 in step S01 of FIG. 3 will be described with reference to the flowchart shown in FIG. 4 and FIGS.

[0046] First, the control unit 114a instructs the voltage / current generating unit 114b to set the operation check terminal 100c to a potential of 0V (step S11), and then inputs a voltage signal of voltage Vmi to the input terminal 100a to generate a current Im (step S12). The storage unit 116 stores in advance that the resistance value of the operation check resistor 104 is R, and the voltage Vmi is determined by the following equation: current Im=voltage Vmi / resistance value R.

[0047] A current Im, which is the same as the current flowing through the operation confirmation resistor 104 generated in step S12, flows through the current sensing resistor 102 (step S13), and the differential voltage generated across the current sensing resistor 102 is amplified by the instrumentation differential amplifier 103, which has a gain set to G, and outputs a voltage signal of the voltage Vmo from the output terminal 100b. The control unit 114a instructs the measurement unit 114c to measure the voltage Vmo (step S14).

[0048] The control unit 114a calculates the current Is flowing through the current sensing resistor 102 using the following equation: Current Is = (Voltage Vmo / Gain G) / Resistance R (step S15), and determines whether the current Is matches the intended current Im (step S16). If the control unit 114a determines that the current Is matches the current Im, it determines that the measurement circuit 100 can measure the current normally (step S17) and terminates the processing of the fault detection program P1. If the control unit 114a determines that the current Is does not match the current Im, it determines that the measurement circuit 100 is abnormal (step S18), warns the user, and terminates the processing of the fault detection program P1. The criterion for determining whether the current Is matches the current Im can be selected appropriately. For example, it may be determined that the current Is matches the current Im if it is within a predetermined range.

[0049] In this way, the control unit 114a executes the failure detection program P1 to confirm that the measuring circuit 100 can measure current normally.

[0050] Next, the operation of the correction value acquisition program P2 in step S02 of FIG. 3 will be described with reference to the flowchart shown in FIG. 5 and FIGS.

[0051] First, the control unit 114a inputs a terminal control signal to the terminal control unit 107 via the communication unit 115, and sets the operation check terminal 100c to an open state (step S21). Since no DUT is connected to the measurement terminal 100d, the measurement terminal 100d is in an open state.

[0052] The control unit 114a instructs the voltage / current generating unit 114b to input a voltage signal of voltage Vci to the input terminal 100a, causing the voltage follower to generate voltage Vci at the measurement terminal 100d (step S22). Then, a leakage current Ic flows through the current sensing resistor 102 (step S23), and the instrumentation differential amplifier 103 amplifies the differential voltage generated across the current sensing resistor 102 and outputs a voltage signal of voltage Vco from the output terminal 100b. The control unit 114a then causes the measuring unit 114c to measure voltage Vco (step S24).

[0053] The control unit 114a calculates the leakage current Ic flowing through the current sensing resistor 102 using the following equation: leakage current Ic=(voltage Vco / gain G) / resistance value R (step S25). The control unit 114a acquires the calculated leakage current Ic as a correction value (step S26), stores it in the storage unit 116, and ends the processing of the correction value acquisition program P2.

[0054] In this way, the control unit 114a executes the correction value acquisition program P2 to acquire the correction values.

[0055] Next, the operation of the minute current measurement program P3 in step S03 of FIG. 3 will be described with reference to the flowchart shown in FIG. 6 and FIGS.

[0056] First, the control unit 114a inputs a terminal control signal to the terminal control unit 107 via the communication unit 115, opens the operation check terminal 100c, and connects the measurement terminal 100d to the DUT (step S31). The control unit 114a instructs the voltage / current generation unit 114b to input a voltage signal of voltage Vdi to the input terminal 100a, causing voltage Vdi to be applied to the measurement terminal 100d (step S32). Then, the current Id generated in the state of step S32 flows through the current sensing resistor 102 (step S33). The instrumentation differential amplifier 103 amplifies the differential voltage generated across the current sensing resistor 102 and outputs a voltage signal of voltage Vdo from the output terminal 100b. The control unit 114a then causes the measurement unit 114c to measure voltage Vdo (step S34).

[0057] The control unit 114a calculates the current Id flowing through the current sensing resistor 102 using the following equation: current Id=(voltage Vdo / gain G) / resistance value R (step S35). The control unit 114a corrects the calculated current Id with a correction value (leakage current) Ic to obtain a corrected current value (Id+Ic) (step S36), stores it in the storage unit 116, and terminates the processing of the minute current measurement program P3.

[0058] As described above, the measurement circuit according to one embodiment of the present invention is an additional measurement circuit that is controlled by a test device and performs fault detection, correction value acquisition, and minute current measurement of a device under test. This measurement circuit includes an operational amplifier forming a voltage follower that outputs a voltage equal to a voltage signal input from the test device to a measurement terminal connected to the device under test during minute current measurement, a current sensing resistor connected between the output terminal of the operational amplifier and the measurement terminal, an instrumentation differential amplifier having two input terminals connected to both ends of the current sensing resistor, respectively, that amplifies a differential voltage generated across the current sensing resistor and outputs the amplified voltage to the test device, and an operation verification resistor that has one end connected between the input terminal of the operational amplifier and the current sensing resistor, forming a feedback loop of the voltage follower, and the other end connected to an operation verification terminal that is set to an open state or grounded by the test device. As a result, this measurement circuit processes the voltage signal and the state of the operation confirmation terminal by the inspection device, and even when combined with an inspection device with low current measurement accuracy, it can accurately measure minute currents in a small space, and the inspection device can detect faults and obtain current correction values.

[0059] In this embodiment, the operation check terminal is set to an open state by the terminal control unit of the measurement circuit, but this is not limited to this. The voltage / current generating unit may set the connection with the operation check terminal to a high impedance, thereby setting the operation check terminal to an open state. [Explanation of symbols]

[0060] 10 Measurement System 100 measurement circuit 100a input terminal 100b output terminal 100c Operation check terminal 100d measurement terminal 100e terminal control terminal 101 Operational Amplifier 102 Current Sensing Resistor 103 Instrumentation Differential Amplifier 104 Operation check resistor 105 Terminal control device 106 Circuit section 107 Terminal control section 110 Semiconductor inspection equipment (inspection equipment) 111 SMU 112 Communication Interface 113 Storage device 114 Measurement Unit 114a Control unit 114b Voltage and current generating unit 114c Measuring section 115 Communications Department 116 Storage section

Claims

1. An additional measurement circuit that is controlled by the inspection device and performs fault detection, correction value acquisition, and minute current measurement of the device under test, an operational amplifier forming a voltage follower that outputs a voltage equal to a voltage signal input from the inspection device to a measurement terminal connected to the device under test when measuring the minute current; a current sensing resistor connected between the output terminal of the operational amplifier and the measurement terminal; an instrumentation differential amplifier having two input terminals connected to both ends of the current sensing resistor, and amplifying a differential voltage generated across the current sensing resistor and outputting the amplified voltage to the testing device; an operation check resistor having one end connected between the input terminal of the operational amplifier forming a feedback loop of the voltage follower and the current sensing resistor, and the other end connected to an operation check terminal that is set to an open state or a ground state by the inspection device; and The measuring circuit is characterized in that the processing is performed by the inspection device changing the state of the voltage signal and the operation confirmation terminal.

2. 2. The measuring circuit according to claim 1, further comprising a terminal control device that causes the inspection device to ground the operation check terminal when the failure is detected.

3. 3. The measurement circuit according to claim 2, wherein the terminal control device causes the inspection device to open the operation check terminal when the correction value is acquired or the minute current is measured.

4. a measurement circuit according to any one of claims 1 to 3; an inspection device that sets the operation check terminal of the measurement circuit in an open state or a ground state, inputs the voltage signal to the measurement circuit, measures the output from the instrumentation differential amplifier, and performs the processing; A measurement system comprising:

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