ATE tester VI source kelvin fault detection method

Abstract

The application relates to the technical field of ATE testing, and particularly discloses a VI source Kelvin fault detection method of an ATE tester, which comprises a constant current source module and a voltage measurement module, the output negative pole of the constant current source is connected with the reference end of the voltage measurement module at a node, and the node is connected with the ground potential of the tester; a switch matrix comprises electrically-controlled switches S1, S2, S3, S4 and S5; wherein the output end of the constant current source is connected with an HF line through the electrically-controlled switch S1 and connected with an HS line through the electrically-controlled switch S2; the input end of the voltage measurement module is connected with an LS line through the electrically-controlled switch S3; the HF line is connected with an LF line through the electrically-controlled switch S5, and the HS line is connected with the LF line through the electrically-controlled switch S4; and the LF line is connected with the node to form a current loop. The Kelvin detection of the VI source in the ATE tester industry decouples signals and sensors, prevents overdrive or undervoltage faults caused by line loss voltage drop, and is safer and more reliable.

Description

Technical Field

[0001] This invention relates to the field of ATE testing technology, and specifically to a method for detecting Kelvin faults in the VI source of an ATE testing machine. Background Technology

[0002] In the field of semiconductor ATE testing, the VI source is a core module for testing devices under test (DUTs) such as chips and power devices. It integrates voltage output, current output, and parameter measurement functions, and can flexibly switch between multiple operating modes. To eliminate measurement errors caused by test cables, probes, and contact resistance, the industry generally adopts a Kelvin four-wire connection method. HF and LF form the current drive circuit, and HS and LS form the voltage detection circuit. The two circuits are independent of each other, thus ensuring high-precision test results. This connection method is also the standard for testing high-current, low-impedance devices.

[0003] In actual mass production, testing equipment needs to frequently perform docking and plugging / unplugging operations. Long-term use can easily lead to problems such as probe aging, pin oxidation, and loose wiring, resulting in loose connections or open circuits on the four signal lines. If the Kelvin connection status is not checked beforehand, it will not only cause distorted test data and batch misjudgments, but also cause overdrive and undervoltage problems due to abnormal loop voltage drops, and in severe cases, burn out the device under test and the test hardware. Therefore, conducting Kelvin link fault detection before testing is a critical step in ensuring the normal operation of the production line.

[0004] Currently, mainstream testing solutions in the industry rely on external switches, resistors, and constant current sources to diagnose faults. These solutions can distinguish between fault states in high-end and low-end combined links, meeting basic testing requirements. However, this approach has significant drawbacks. It can only determine the fault area and cannot pinpoint the specific faulty line within the HF, HS, LF, and LS channels. Fault diagnosis relies on manual line-by-line inspection, significantly reducing production efficiency. Furthermore, traditional solutions fail to completely separate the current path from the voltage detection path, which can easily lead to voltage drop interference in high-current testing scenarios, posing safety hazards. Additionally, the external components have complex structures and high hardware costs. Summary of the Invention

[0005] The purpose of this invention is to provide a method for detecting Kelvin faults in the VI source of an ATE tester, so as to solve the above-mentioned technical problems.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for detecting Kelvin faults in the VI source of an ATE tester includes a current / voltage output port HF, a voltage detection and feedback port HS, a voltage detection and feedback reference ground port LS, and a current return port or a voltage reference ground port LF in a four-wire Kelvin circuit. Each wire is connected to the DUT interface through a contact resistor. The method also includes: The constant current source module and the voltage measurement module are connected together at a node, with the negative output terminal of the constant current source and the reference terminal of the voltage measurement module connected to the ground potential of the test machine. A switch matrix containing electronically controlled switches S1, S2, S3, S4, and S5; The output of the constant current source is connected to the HF line via electronic switch S1 and to the HS line via electronic switch S2; the input of the voltage measurement module is connected to the LS line via electronic switch S3; the HF line is connected to the LF line via electronic switch S5, and the HS line is connected to the LF line via electronic switch S4; the LF line is connected to the node to form a current loop.

[0007] As a further aspect of the present invention: HF line detection specifically includes: Close the power control switches S1 and S5 to control the VI source to output a constant current FI, ground the HS line, and detect the voltage difference between the HF line and the HS line; if the voltage difference is 0V, it is determined that the HF line is connected to the DUT normally; if the voltage difference is not 0V, it is determined that the HF line has a loose connection or open circuit fault.

[0008] As a further aspect of the present invention: HS line detection specifically includes: Disconnect the power control switches S1 and S5, close the power control switches S2 and S4, control the VI source to output a constant current FI, ground the HS line, and detect the voltage difference between the HF line and the HS line; if the voltage difference is 0V, it is determined that the HS line is connected normally to the DUT; if the voltage difference is not 0V, it is determined that the HS line has a loose connection or open circuit fault.

[0009] As a further aspect of the present invention: LS line detection specifically includes: Disconnect the power control switches S2 and S4, close the power control switch S3, control the VI source to output a constant current FI, ground the LF line, and detect the voltage difference between the LS line and the LF line; if the voltage difference is 0V, it is determined that the LS line is connected to the DUT normally; if the voltage difference is not 0V, it is determined that the LS line has a loose connection or open circuit fault. Among them, the LF line serves as the current return terminal and voltage reference ground port in the Kelvin four-wire system. When the HF, HS, and LS lines are all detected as normal, the LF line connection is determined to be normal.

[0010] As a further aspect of the present invention: there is a contact resistance Rconnect between the Kelvin four wires and the DUT, and the resistance value of the contact resistance Rconnect is not greater than 1mΩ. The voltage drop caused by the contact resistance is ignored in the voltage difference determination process.

[0011] As a further aspect of the present invention: after all line fault detections are completed, if the four lines HF, HS, LS, and LF are all connected normally, the ATE tester is started to perform formal testing on the DUT; if any line is found to be faulty, the test is immediately terminated and faulty line alarm information is output.

[0012] As a further aspect of the present invention: when a loose connection or open circuit fault is detected in the line, the fault type, fault line number and fault occurrence time are recorded to form a fault log and store it in the local storage unit of the ATE test machine.

[0013] As a further aspect of the present invention: during the detection process, the voltage detection path is a high-resistance path, and no significant current flows through the voltage detection path, thus decoupling the current path from the voltage detection path.

[0014] The beneficial effects of this invention are: it achieves Kelvin detection of the VI source in the ATE tester industry at a lower cost and can locate which line has a connection fault; it decouples the signal (current path) from the sensing (voltage path), and prevents overdrive or undervoltage faults caused by line loss voltage drop in high current scenarios, making it safer and more reliable. Attached Figure Description

[0015] The invention will now be further described with reference to the accompanying drawings.

[0016] Figure 1 This is a schematic diagram of the basic Kelvin four-wire structure connecting the VI source and the DUT in this invention; Figure 2 This is a schematic diagram of the Kelvin connection structure controlled externally by the VI source according to the present invention; Figure 3 This is a schematic diagram of the Kelvin connection structure of the HF / HS link of the present invention without connection to the DUT end; Figure 4 This is a schematic diagram of the Kelvin connection structure of the LF / LS link of the present invention without connection to the DUT end; Figure 5 This is a schematic diagram of the Kelvin connection structure of the HF / HS link and LF / LS link of the present invention without connection to the DUT end; Figure 6 This is a schematic diagram of the HF detection structure of the VI source Kelvin fault detection method for ATE tester according to the present invention; Figure 7 This is a schematic diagram of the HS detection structure of the VI source Kelvin fault detection method for an ATE tester according to the present invention; Figure 8 This is a schematic diagram of the structure of the LS detection method for the VI source Kelvin fault detection of an ATE tester according to the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In ATE testing systems, VI sources are commonly used. Simply put, a VI source can function as both a voltage and current source, measuring both voltage and current. When used as a voltage source, this mode is called FV mode (Force Voltage); when used as a current source, this mode is called FI mode (Force Current); when used to measure voltage, this mode is called MV mode (Measure Voltage); and when used to measure current, this mode is called MI mode (Measure Current). These modes are typically used in combination, namely FVMV, FVMI, FIMV, and FIMI. A VI source generally has four external connection ports: a current / voltage output port HF (High Force), a current return port or voltage reference ground port LF (Low Force), which can also be considered GND; a voltage detection and feedback port HS (High Sense); and a voltage detection and feedback reference ground port LS (Low Sense). In ATE testing, using VI sources for Kelvin testing of the DUT is widely adopted. Its core purpose is to eliminate the influence of test leads, probe cards, and contact resistance on measurement accuracy, obtaining accurate voltage values ​​across the DUT. To ensure the accuracy and repeatability of measurement results, a Kelvin connection is essentially a four-wire measurement method: the HF and LF lines are connected to the DUT to ensure the circuit path functions correctly; the HS and LS lines are connected to the DUT to detect the voltage across the DUT, ensuring accurate output or measured voltage. Before formal testing begins, the Kelvin connection between the VI source and the DUT must be checked. If the connection is good, formal testing can begin; otherwise, it is considered a Kelvin connection fault, which risks damaging the DUT. Figure 1 This is the basic Kelvin four-wire structure for connecting the VI source and the DUT.

[0019] The current detection technology for Kelvin connections uses the following methods: The VI source is controlled externally via switches S1, S2, and S3: FI = 100uA current, switches S1, S2, and S3 are closed, and after closing... Figure 2 The red path in the middle is the current return path, and MV is the voltage. Figure 2The voltage at points A and B is such that when HF / HS and LF / LS are properly connected at the DUT terminals, MV = 0V because S3 short-circuits points A and B.

[0020] Case (1): such as Figure 3 As shown, if the HF / HS link is not properly connected at the DUT end and one end is disconnected, with a current of FI=100uA, and switches S1, S2, and S3 are closed, the current return path becomes as follows, where point A is transferred, and MV is the voltage between points A and B in the diagram, which is 0.25V.

[0021] Case (2): such as Figure 4 As shown, if the LF / LS link is not properly connected at the DUT end and one end is disconnected, with a current of FI=100uA, and switches S1, S2, and S3 are closed, the current return path becomes as follows, where point B is transferred, and MV is the voltage between points A and B in the diagram, which is 0.25V.

[0022] Case (3): such as Figure 5 As shown, if the HF / HS link and LF / LS link are not properly connected at the DUT end, and the current FI = 100uA, and the switches S1, S2, and S3 are closed, then the current return path becomes as follows, where points A and B are both transferred, and MV is the voltage at points A and B in the figure, which is 0.5V.

[0023] The above method has a significant drawback: it can only detect whether the HF / HS or LF / LS is properly connected at the DUT, but it cannot pinpoint which of the four wires is faulty. Technical personnel are required to go to the site for further investigation.

[0024] This invention provides a Kelvin fault detection method for a TE tester VI source. It achieves HF / HS or LF / LS detection in a low-cost manner, pinpointing the specific signal line that is not properly connected. The specific steps are as follows: (1) HF detection, such as Figure 6 As shown, when S1 and S5 are closed, FI = 100uA. The red line represents the current path, and the blue line represents the detection path (high resistance, almost no current flows through it). Rconncet is the contact resistance, which is usually 1mΩ or less (negligible). The voltage drop between HF and HS is detected. Since HS is grounded = 0V, if HF is well connected at the DUT terminal, then the value of MV (voltage difference between points A and B) = 0V. If HF is not connected at the DUT terminal, then MV ≠ 0V. Thus, the connection status of HF can be determined.

[0025] (2) HS testing, such as Figure 7As shown, when S2 and S4 are closed, FI = 100uA. At this time, HS is grounded = 0V. Similarly, the voltage drop between HF and HS is detected. If HS is well connected at the DUT, then the value of MV (voltage difference between points A and B) = 0V. If HS is not connected at the DUT, then MV ≠ 0V. This allows us to determine the connection status of HS.

[0026] (3) LS detection, such as Figure 8 As shown, when S3 is closed, FI = 100uA. At this time, the voltage drop between LS and LF will be detected. LF, i.e. GND, = 0V. If LS is well connected at the DUT, then the value of MV (voltage difference between points A and B) = 0V. If LS is not connected at the DUT, then MV ≠ 0V, thus determining the connection status of LS.

[0027] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for detecting Kelvin faults in a ATE tester VI source, comprising a current / voltage output port HF, a voltage detection and feedback port HS, a voltage detection and feedback reference ground port LS, and a current return port or a voltage reference ground port LF in a four-wire Kelvin circuit, wherein each wire is connected to the DUT interface via a contact resistor, characterized in that, Also includes: The constant current source module and the voltage measurement module are connected together at a node, with the negative output terminal of the constant current source and the reference terminal of the voltage measurement module connected to the ground potential of the test machine. A switch matrix containing electronically controlled switches S1, S2, S3, S4, and S5; The output of the constant current source is connected to the HF line via electronic switch S1 and to the HS line via electronic switch S2; the input of the voltage measurement module is connected to the LS line via electronic switch S3; the HF line is connected to the LF line via electronic switch S4, and the HS line is connected to the LF line via electronic switch S5; the LF line is connected to the node to form a current loop.

2. The method for detecting Kelvin faults in the VI source of an ATE tester according to claim 1, characterized in that, HF line testing specifically includes: Close the power control switches S1 and S5 to control the VI source to output a constant current FI, ground the HS line, and detect the voltage difference between the HF line and the LF line; if the voltage difference is 0V, it is determined that the HF line is connected to the DUT normally; if the voltage difference is not 0V, it is determined that the HF line has a loose connection or open circuit fault.

3. The method for detecting Kelvin faults in the VI source of an ATE tester according to claim 1, characterized in that, HS line testing specifically includes: Disconnect the power control switches S1 and S5, close the power control switches S2 and S4, control the VI source to output a constant current FI, ground the HS line, and detect the voltage difference between the HS line and the LF line; if the voltage difference is 0V, it is determined that the HS line is connected to the DUT normally; if the voltage difference is not 0V, it is determined that the HS line has a loose connection or open circuit fault.

4. The method for detecting Kelvin faults in the VI source of an ATE tester according to claim 1, characterized in that, LS line testing specifically includes: Disconnect the power control switches S2 and S4, close the power control switch S3, control the VI source to output a constant current FI, ground the LF line, and detect the voltage difference between the LS line and the LF line; if the voltage difference is 0V, it is determined that the LS line is connected to the DUT normally; if the voltage difference is not 0V, it is determined that the LS line has a loose connection or open circuit fault. Among them, the LF line serves as the current return terminal and voltage reference ground port in the Kelvin four-wire system. When the HF, HS, and LS lines are all detected as normal, the LF line connection is determined to be normal.

5. The method for detecting Kelvin faults in the VI source of an ATE tester according to claim 1, characterized in that, There is a contact resistance Rconnect between the Kelvin four wires and the DUT. The resistance of the contact resistance Rconnect is not greater than 1mΩ. The voltage drop caused by the contact resistance is ignored in the voltage difference determination process.

6. The method for detecting Kelvin faults in the VI source of an ATE tester according to claim 1, characterized in that, After all line fault detections are completed, if the HF, HS, LS, and LF lines are all connected normally, start the ATE tester to perform formal testing on the DUT; if a fault is detected in any line, immediately terminate the test and output a fault line alarm message.

7. The method for detecting Kelvin faults in the VI source of an ATE tester according to claim 1, characterized in that, When a loose connection or open circuit fault is detected in the line, the fault type, fault line number and fault occurrence time are recorded to form a fault log and store it in the local storage unit of the ATE test machine.

8. The method for detecting Kelvin faults in the VI source of an ATE tester according to claim 1, characterized in that, During the detection process, the voltage detection path is a high-resistance path, and no significant current flows through the voltage detection path. The current path and the voltage detection path are decoupled from each other.

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