Measurement circuit and measurement system using the same

Abstract

To ensure the reliability of the measurement circuit, we provide a measurement circuit that can detect circuit failures and disconnections with a simple configuration. [Solution] The measurement circuit 100 includes a buffer circuit (operational amplifier 101) that outputs a voltage corresponding to the voltage signal from the inspection device 110, a current sensing resistor 102 between the output side of the buffer circuit and the measurement terminal 100d, a differential amplifier circuit (instrumentation differential amplifier 103) that amplifies the voltage across the current sensing resistor 102 and outputs it to the inspection device 110, and an operation confirmation resistor 104, one end of which is connected to the feedback loop of the buffer circuit and the other end of which is connected to an operation confirmation terminal 100c that is opened or grounded by the inspection device 110.

Description

Technical Field

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

Background Art

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

[0003] Regarding the electrical inspection of semiconductor devices among electronic components, a measurement accuracy of the order of nA is required, and the conventional semiconductor inspection device may have insufficient measurement accuracy of current. For this reason, various proposals have been made for methods and devices for measuring minute currents.

[0004] For example, a method has been proposed in which the leakage current value is measured in a state where the object to be measured is not electrically connected, the minute current value flowing through the object to be measured is measured in a state where the object to be measured is mounted, 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, generally, it is difficult for a conventional semiconductor inspection device to measure a minute current of, for example, 10 nA or less. When trying to further add a high-precision measuring instrument to a conventional semiconductor inspection device, for example, it may be difficult to secure space for installing the measuring instrument, or the tact time may increase due to complicated communication control between the semiconductor inspection device and the measuring instrument.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] One aspect of the present invention is to provide a measurement circuit that can detect failures or disconnections in the circuit itself with a simple configuration, in order to ensure the reliability of the measurement circuit. [Means for solving the problem]

[0008] The measurement circuit in one embodiment of the present invention is An additional measurement circuit controlled by the inspection device, which performs fault detection processing, A buffer circuit that outputs a voltage equal to the voltage signal input from the inspection device to the measurement terminal connected to the device under test during the measurement of the minute current, A current sensing resistor connected between the output terminal of the buffer circuit and the measurement terminal, Two input terminals are connected to each of the current sensing resistors, and a differential amplifier circuit amplifies the differential voltage generated across the current sensing resistors and outputs it to the inspection device. An operation confirmation resistor, one end of which is connected to the feedback loop of the buffer circuit and the other end of which is connected to an operation confirmation terminal that is opened or grounded by the inspection device, It has, The fault detection process is performed when the voltage signal and the state of the operation confirmation terminal change due to the inspection device. [Effects of the Invention]

[0009] According to one aspect of the present invention, in order to ensure the reliability of the measurement circuit, it is possible to provide a measurement circuit that can detect failures or disconnections in the circuit itself with a simple configuration. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a block diagram showing the hardware configuration of the measurement circuit and measurement system in this embodiment. [Figure 2] Figure 2 is a block diagram showing the functional configuration of the measurement circuit and measurement system in this embodiment. [Figure 3]Figure 3 is a flowchart showing the sequence of processes related to minute current measurement in this embodiment. [Figure 4] Figure 4 is a flowchart showing the process flow for detecting a fault in the measurement circuit in this embodiment. [Figure 5] Figure 5 is a flowchart showing the process flow for obtaining the current correction value in this embodiment. [Figure 6] Figure 6 is a flowchart showing the process flow for measuring minute currents in this embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, one embodiment for carrying out the present invention will be described in detail with reference to the drawings. In drawings, identical components are denoted by the same reference numeral, and redundant explanations may be omitted.

[0012] Figure 1 is a block diagram showing the hardware configuration of the measurement circuit and measurement system in this embodiment. As shown in Figure 1, the measurement system 10 in this embodiment is a system that adds a measurement circuit 100 to a commercially available semiconductor inspection device 110, which has difficulty measuring current values ​​on the order of nA, to enable the measurement of current values ​​on the order of nA. Based on the signals and voltages input from the semiconductor inspection device 110 to the measurement circuit 100, this measurement system 10 can not only measure minute currents of semiconductor devices, which are devices under test (DUTs) connected to the measurement circuit 100, but also perform fault detection of the measurement circuit 100 and acquire current correction values.

[0013] The measurement circuit 100 is an additional circuit controlled by the semiconductor inspection device 110 that performs fault detection, correction value acquisition, and measurement of minute currents of the device under test. This measurement circuit 100 includes an operational amplifier 101, a current sensing resistor 102, an instrumentation differential amplifier 103 as a differential amplification circuit, an operation confirmation resistor 104, and a terminal control device 105. Further, the measurement circuit 100 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 from the semiconductor inspection apparatus 110 to the input terminal 100a with respect to the measurement terminal 100d connected to the DUT during minute current measurement. That is, the operational amplifier 101 functions as a buffer circuit.

[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, respectively, and amplifies the differential voltage generated at both ends of the current sensing resistor 102 and outputs it as a voltage signal to the output terminal 100b.

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

[0018] The terminal control device 105 controls the operation confirmation terminal 100c to an open state or a grounded state based on the terminal control signal input from the semiconductor inspection apparatus 110.

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

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

[0021] The SMU111 can input and output voltage signals to the measurement circuit 100 using various programs stored in the memory device 113 to measure minute currents in the DUT, as well as detect faults in the measurement circuit 100 and acquire correction values. This SMU111 comprises an MCU (Micro Controller Unit) 111a, a voltage and current generator 111b, and a measuring device 111c.

[0022] The MCU (Micro Controller Unit) 111a is a control unit for controlling the voltage and current generator 111b, the measuring device 111c, and the measuring circuit 100. The voltage-current generator 111b is formed by 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 to control the operation confirmation terminal 100c of the measurement circuit 100 to an open state or a ground state, and outputs the input terminal control signal to the terminal control device 105.

[0024] The storage device 113 is, for example, an HDD (Hard Disk Drive) that stores programs, data, etc.

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

[0026] The circuit section 106 is implemented 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 implemented by the terminal control device 105. In the fault detection program P1, the terminal control unit 107 sets the operation confirmation terminal 100c to a ground state (potential of 0V), and in the correction value acquisition program P2 and the minute current measurement program P3, it sets the operation confirmation terminal 100c to an open state.

[0028] The semiconductor inspection apparatus 110 includes a measurement unit 114, a communication unit 115, and a storage unit 116.

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

[0030] The control unit 114a is implemented by the MCU 111a and controls the entire measurement system 10. Based on various programs stored in the memory unit 116, the control unit 114a can input and output voltage signals to the measurement circuit 100 to measure minute currents in the DUT, as well as detect faults in the measurement circuit 100 and acquire correction values. The operation of these control units 114a will be described later in the explanation of the processing of the various programs shown in Figures 3 to 6.

[0031] The voltage-current generation unit 114b is implemented by the voltage-current generation device 111b. This voltage-current generation unit 114b can input a voltage signal of a predetermined voltage to the input terminal 100a upon instruction from the control unit 114a.

[0032] The measurement unit 114c is implemented by the measurement device 111c. This measurement unit 114c determines the current value from the voltage signal output from the output terminal 100b of the circuit unit 106.

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

[0034] The memory unit 116 stores the automatic measurement program P0, the minute current measurement program P3, the correction value acquisition program P2, and the fault 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, sequentially measuring the current of multiple DUTs and determining whether each DUT is good or not.

[0036] In the fault detection program P1, the control unit 114a performs a process to detect a fault in the measurement circuit 100. Specifically, when the fault detection program P1 is executed, the control unit 114a sets the operation confirmation terminal 100c to a potential of 0V, inputs a voltage signal to the input terminal 100a, and causes current to flow through the current sensing resistor 102. The measurement circuit 100 outputs a voltage signal to the measurement unit 114c, which is amplified by the instrumentation differential amplifier 103 set to gain G, from the differential voltage generated across the current sensing resistor 102. 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 detects a fault in the measurement circuit 100 by determining whether or not it matches the intended current.

[0037] In the correction value acquisition program P2, the control unit 114a performs the process of acquiring the correction value. 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, opening the operation confirmation terminal 100c, inputting a voltage signal to the input terminal 100a to generate a predetermined voltage at the measurement terminal 100d, and causing a leakage current to flow through the current sensing resistor 102. The measurement circuit 100 outputs a voltage signal to the measurement unit 114c, which is amplified by the instrumentation differential amplifier 103 set to gain G, from the differential voltage generated across the current sensing resistor 102. The control unit 114a instructs the measurement unit 114c to measure the voltage signal from the measurement circuit 100, calculate 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 the process of measuring 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 current to flow through the current sensing resistor 102. The measurement circuit 100 outputs a voltage signal to the measurement unit 114c, which is amplified by the instrumentation differential amplifier 103 set to gain G, from the differential voltage generated across the current sensing resistor 102. The control unit 114a instructs the measurement unit 114c to measure the voltage signal from the measurement circuit 100, calculate 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 with the correction value acquired by the correction value acquisition program P2 to obtain the "corrected current value".

[0039] Here, the series of processes related to minute current measurement performed by the measurement system 10 will be explained following the flowchart shown in Figure 3, with reference to Figures 1 and 2.

[0040] First, the control unit 114a reads the automatic measurement program P0 from the storage unit 116 in response to the user's instruction. Then, as shown in Figure 3, the control unit 114a checks whether the measurement circuit 100 is operating normally using the fault detection program P1 (step S01), and obtains the 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 obtained in step S02 (step S03). The detailed processing 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). If it determines that the corrected current value is within the test standard, it determines that the DUT is a good product (step S05). If it determines that the corrected current value is not within the test standard, it determines that the DUT is a defective product (step S06).

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

[0044] In this way, the control unit 114a reads and executes an automatic measurement program P0 from the storage unit 116, which uses a fault detection program P1, a correction value acquisition program P2, and a minute current measurement program P3, thereby performing a series of processes related to minute current measurement.

[0045] Next, the operation of the fault detection program P1 in step S01 of Figure 3 will be explained following the flowchart shown in Figure 4, with reference to Figures 1 and 2.

[0046] First, the control unit 114a instructs the voltage-current generation unit 114b to set the operation confirmation 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 memory unit 116 has pre-stored that the resistance value of the operation confirmation resistor 104 is R, and the voltage Vmi is determined by the following equation: Current Im = Voltage Vmi / Resistance R.

[0047] A current Im, the same current Im that flows through the operation confirmation resistor 104 generated in step S12, flows through the current sensing resistor 102 (step S13). The differential voltage generated across the current sensing resistor 102 is amplified by the instrumentation differential amplifier 103, which is set to gain G, and a voltage signal of voltage Vmo is output 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 formula: 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 in 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 in the fault detection program P1. The criteria for determining whether current Is matches current Im can be selected as appropriate. For example, it may be determined that they match if current Is is within a predetermined range.

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

[0050] Next, the operation of the correction value acquisition program P2 in step S02 of Figure 3 will be explained following the flowchart shown in Figure 5, with reference to Figures 1 and 2.

[0051] First, the control unit 114a inputs a terminal control signal to the terminal control unit 107 via the communication unit 115, and opens the operation confirmation terminal 100c (step S21). Since the DUT is not connected to measurement terminal 100d, measurement terminal 100d is in an open state.

[0052] The control unit 114a instructs the voltage-current generation unit 114b to input a voltage signal Vci to the input terminal 100a, and the voltage follower generates a 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 Vco from the output terminal 100b. The control unit 114a causes the measurement unit 114c to measure the voltage Vco (step S24).

[0053] The control unit 114a calculates the leakage current Ic flowing through the current sensing resistor 102 using the following formula: 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 terminates the processing in the correction value acquisition program P2.

[0054] In this way, the control unit 114a acquires the correction value by executing the correction value acquisition program P2.

[0055] Next, the operation of the minute current measurement program P3 in step S03 of Figure 3 will be explained following the flowchart shown in Figure 6, with reference to Figures 1 and 2.

[0056] First, the control unit 114a inputs a terminal control signal to the terminal control unit 107 via the communication unit 115, opening the operation confirmation terminal 100c and connecting 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, so that voltage Vdi is applied to the measurement terminal 100d (step S32). As a result, the current Id generated in step S32 flows through the current sensing resistor 102 (step S33), and 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 instructs the measurement unit 114c to measure the voltage Vdo (step S34).

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

[0058] As described above, the measurement circuit in one embodiment of the present invention is an additional measurement circuit controlled by the inspection device that performs fault detection, correction value acquisition, and measurement of minute currents of the device under test. This measurement circuit includes a buffer circuit that outputs a voltage equal to the voltage signal input from the inspection device to a measurement terminal connected to the device under test when measuring minute currents, a current sensing resistor connected between the output terminal of the buffer circuit and the measurement terminal, a differential amplifier circuit with two input terminals connected to both ends of the current sensing resistor that amplifies the differential voltage generated across the current sensing resistor and outputs it to the inspection device, and an operation confirmation resistor, one end of which is connected to the feedback loop of the buffer circuit and the other end of which is connected to an operation confirmation terminal that is left open or grounded by the inspection device. As a result, this measurement circuit processes changes in voltage signals and the state of operation confirmation terminals by the inspection device, allowing for accurate measurement of minute currents in a small space even when combined with inspection devices that have low current measurement accuracy, and enabling fault detection and acquisition of current correction values ​​by the inspection device.

[0059] In this embodiment, the operation confirmation terminal is left open by the terminal control unit of the measurement circuit. However, the invention is not limited to this, and the connection to the operation confirmation terminal may be made high impedance by the voltage and current generation unit, leaving the operation confirmation terminal open. [Explanation of Symbols]

[0060] 10 Measurement Systems 100 measurement circuit 100a Input Terminal 100b output terminal 100c Operation Confirmation Terminal 100d measurement terminal 100e Terminal control terminal 101 Operational Amplifier (Buffer Circuit) 102 Current-sensing resistor 103 Instrumentation Differential Amplifier (Differential Amplifier Circuit) 104 Operation check resistor 105 Terminal control device 106 Circuit section 107 Terminal Control Unit 110 Semiconductor inspection equipment (inspection equipment) 111 SMU 112 Communication Interface 113 Storage device 114 Measurement Unit 114a Control Unit 114b Voltage and current generation section 114c Measuring part 115 Communications Department 116 Memory section

Claims

1. An additional measurement circuit controlled by the inspection device, which performs fault detection processing, A buffer circuit that outputs a voltage equal to the voltage signal input from the inspection device to the measurement terminal connected to the device under test during the measurement of the minute current, A current sensing resistor connected between the output terminal of the buffer circuit and the measurement terminal, Two input terminals are connected to each of the current sensing resistor, and a differential amplifier circuit amplifies the differential voltage generated across the current sensing resistor and outputs it to the inspection device, An operation confirmation resistor, one end of which is connected to the feedback loop of the buffer circuit and the other end of which is connected to an operation confirmation terminal that is opened or grounded by the inspection device, It has, A measurement circuit characterized in that the fault detection process is performed when the voltage signal and the state of the operation confirmation terminal change due to the inspection device.

2. The measurement circuit according to claim 1, further comprising a terminal control device that, in the event of fault detection, uses the inspection device to set the operation confirmation terminal to a ground state.

3. The measurement circuit according to claim 2, wherein when a device to be measured is connected to the measurement terminal and current measurement is performed, the terminal control device opens the operation confirmation terminal using the inspection device.

4. A measurement circuit according to any one of claims 1 to 3, An inspection device that opens the operation confirmation terminal in the measurement circuit or puts it to ground, inputs the voltage signal to the measurement circuit, measures the output from the differential amplifier circuit and performs the fault detection process, A measurement system characterized by having the following features.

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