Junction capacitance parameter measuring device

Abstract

The utility model relates to a junction capacitance parameter measuring device which comprises a direct-current power supply, an energy storage module, a test loop and an impedance tester. The DC power supply is connected with the energy storage module. The test loop is connected with the energy storage module, the impedance tester and a semiconductor tube to be tested. The DC power supply is used for charging the energy storage module, and the test loop applies voltage to the semiconductor tube according to the voltage after the energy storage module is charged, so that the impedance tester performs junction capacitance parameter measurement on the semiconductor tube through the test loop, a high-performance power supply does not need to be used for power supply, low-cost junction capacitance parameter measurement is realized, and the measurement cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor testing, in particular to a junction capacitance parameter measurement device. BACKGROUND

[0002] Junction capacitance is a property of field effect transistors (FETs) that greatly affects their switching performance and high-frequency characteristics. Taking a common metal-oxide-semiconductor field effect transistor (MOSFET) as an example, its junction capacitance refers to the gate-drain capacitance (Cgd), gate-source capacitance (Cgs), and drain-source capacitance (Cds). The traditional junction capacitance parameter testing scheme mainly uses an independent tester to test the junction capacitance. The drain-source voltage can reach about one kilovolt, so the testing system needs to use a high-voltage, high-performance power supply to provide high-voltage bias to realize the testing environment, and the measurement cost is high. CONTENT OF THE UTILITY MODEL

[0003] Therefore, it is necessary to provide a junction capacitance parameter measurement device that can reduce the measurement cost in view of the above problems.

[0004] A junction capacitance parameter measurement device, comprising a direct current power supply, an energy storage module, a test loop, and an impedance tester; the direct current power supply is connected to the energy storage module, the test loop is connected to the energy storage module, the impedance tester, and a semiconductor tube to be tested; the direct current power supply is used to charge the energy storage module, and the test loop applies a voltage to the semiconductor tube according to the voltage of the energy storage module after charging, so that the impedance tester measures the junction capacitance parameters of the semiconductor tube through the test loop.

[0005] In one of the embodiments, the test loop comprises a switch K11 and a current limiting component, and the switch K11 and the current limiting component are connected in series between the energy storage module and the semiconductor tube.

[0006] In one of the embodiments, the test loop further comprises a bypass conduction component, the bypass conduction component is connected in parallel with the current limiting component, and the conduction resistance of the bypass conduction component is smaller than the conduction resistance of the current limiting component.

[0007] In one of the embodiments, the test circuit further comprises a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a switch K1, a switch K2, a switch K3, a switch K4, a switch K5, a switch K6 and a switch K7, the HCUR port and the HPOT port of the impedance tester are connected to the capacitor C1 and the capacitor C2 respectively, the capacitor C1 is connected to the GF line through the switch K1 and to the DF line through the switch K5, the capacitor C2 is connected to the GS line through the switch K1 and to the DS line through the switch K5; the LCUR port and the LPOT port of the impedance tester are connected to the capacitor C3 and the capacitor C4 respectively, the capacitor C3 is connected to the GF line through the switch K2 and to the SF line through the switch K3, the capacitor C4 is connected to the GS line through the switch K2 and to the SS line through the switch K3; the switch K7 and the capacitor C5 are connected in series and then connected between the DS line and the SS line, the DS line is connected to the first end of the energy storage module through the corresponding current limiting component, bypass conduction component and switch K11, the SS line is connected to the second end of the energy storage module through the corresponding current limiting component, bypass conduction component and switch K11; the GF line is connected to the SF line through the switch K6, and the SF line is connected to the ground through the switch K4; wherein the GF line and the GS line are connected to the control end of the semiconductor tube, the DF line and the DS line are connected to the first end of the semiconductor tube, and the SF line and the SS line are connected to the second end of the semiconductor tube.

[0008] In one of the embodiments, the junction capacitance parameter measurement device further comprises a switch K10, and the DC power supply is connected to the energy storage module through the switch K10; the switch K10 is in an on state during the mass production test, so that the DC power supply continuously charges the energy storage module.

[0009] In one of the embodiments, the energy storage module is a high-voltage capacitor, a patch capacitor or an electrolytic capacitor.

[0010] In one of the embodiments, the junction capacitance parameter measurement device further comprises a voltage detection module connected to the energy storage module, the voltage detection module is used to detect the voltage of the energy storage module and / or the voltage applied to the semiconductor tube.

[0011] In one of the embodiments, the junction capacitance parameter measurement device further comprises a control module, the control module is connected to the switches in the test circuit, the voltage detection module, the DC power supply and the impedance tester.

[0012] In one of the embodiments, the voltage detection module comprises a proportional operational amplifier circuit, a reverse operational amplifier circuit, a summing circuit and an analog-to-digital converter, the proportional operational amplifier circuit is connected to the energy storage module and the summing circuit, the reverse operational amplifier circuit is connected to the energy storage module and the summing circuit, the summing circuit is connected to the analog-to-digital converter, and the analog-to-digital converter is connected to the control module.

[0013] In one of the embodiments, the proportional operational amplifier circuit comprises an operational amplifier U1, a resistor R11 and a resistor R14, the reverse operational amplifier circuit comprises an operational amplifier U2, an operational amplifier U3, a resistor R12, a resistor R13 and a resistor R15, and the summing circuit comprises an operational amplifier U4 and a resistor R16.

[0014] The non-inverting input terminal of the operational amplifier U1 is connected to the first terminal of the energy storage module, the inverting input terminal of the operational amplifier U1 is connected to the output terminal of the operational amplifier U1 through the resistor R11, the output terminal of the operational amplifier U1 is connected to the inverting input terminal of the operational amplifier U4 through the resistor R14, the non-inverting input terminal of the operational amplifier U2 is connected to the second terminal of the energy storage module, the inverting input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2 through the resistor R12, the output terminal of the operational amplifier U2 is connected to the inverting input terminal of the operational amplifier U3, the inverting input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U3 through the resistor R13, the non-inverting input terminal of the operational amplifier U3 is grounded, the output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U4 through the resistor R15, the inverting input terminal of the operational amplifier U4 is connected to the output terminal of the operational amplifier U4 through the resistor R16, the non-inverting input terminal of the operational amplifier U4 is grounded, and the output terminal of the operational amplifier U4 is connected to the analog-to-digital converter.

[0015] In one of the embodiments, the junction capacitance parameter measurement device further comprises a discharge module, the discharge module is connected to the energy storage module, and the discharge module discharges the voltage of the energy storage module when turned on.

[0016] In one of the embodiments, the discharge module comprises a switch tube Q1, a switch tube Q2 and a resistor R17, the control terminals of the switch tube Q1 and the switch tube Q2 are connected to an isolated power supply, the first terminal of the switch tube Q1 is connected to the energy storage module, the second terminal of the switch tube Q1 is connected to the first terminal of the switch tube Q2, and the second terminal of the switch tube Q2 is grounded through the resistor R17.

[0017] The junction capacitance parameter measuring device charges the energy storage module by using a direct current power supply, and the test loop applies voltage to the semiconductor tube according to the voltage of the charged energy storage module, so that the impedance tester measures the junction capacitance parameters of the semiconductor tube through the test loop, without using a high-performance power supply for power supply, realizing low-cost junction capacitance parameter measurement, and reducing the measurement cost. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structural block diagram of the junction capacitance parameter measuring device in one embodiment.

[0019] Figure 2 It is a structural schematic diagram of the junction capacitance parameter measuring device in one embodiment.

[0020] Figure 3 It is a structural schematic diagram of the voltage detection module in one embodiment.

[0021] Figure 4 It is a structural schematic diagram of the discharge module in one embodiment.

[0022] Figure 5 It is a Rg / Ciss test loop schematic diagram in one embodiment.

[0023] Figure 6 It is a Coss test loop schematic diagram in one embodiment.

[0024] Figure 7 It is a Crss test loop schematic diagram in one embodiment.

[0025] Figure 8 It is a Ciss test flowchart in one embodiment. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is only for the purpose of describing specific embodiments of the application and is not intended to limit the application.

[0028] It can be understood that, in the following embodiments, "connection" between the circuits, modules, units, etc. connected to each other should be understood as "electrical connection", "communication connection" and the like if there is transmission of electrical signals or data between them.

[0029] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, operations, components, parts, or combinations thereof.

[0030] In one embodiment, such as Figure 1 As shown, a junction capacitance parameter measurement device is provided, including a DC power supply 110, an energy storage module 120, a test circuit 130, and an impedance meter (LCR). The DC power supply 110 is connected to the energy storage module 120, and the test circuit 130 is connected to the energy storage module 120, the impedance meter (LCR), and the semiconductor transistor under test. The DC power supply 110 is used to charge the energy storage module 120. The test circuit 130 applies a voltage to the semiconductor transistor based on the voltage after the energy storage module 120 is charged, so that the impedance meter (LCR) can measure the junction capacitance parameter of the semiconductor transistor through the test circuit 130. The semiconductor transistor can be a MOSFET, IGBT, PIM packaged transistor, etc. The DC power supply 110 can be a DC regulated power supply. The energy storage module 120 can specifically be an energy storage capacitor, such as a high-voltage capacitor, a surface-mount capacitor, or an electrolytic capacitor. The energy storage module 120 is connected to the first and second terminals of the semiconductor transistor through the test circuit 130 to apply the high voltage required for the test. The impedance meter (LCR) is connected to the control terminal, the first terminal, and the second terminal of the semiconductor transistor through the test circuit 130 to measure the junction capacitance parameter. Taking a MOSFET as an example, the gate (G) can be used as the control terminal, the drain (D) as the first terminal, and the source (S) as the second terminal.

[0031] In one embodiment, such as Figure 1 As shown, the junction capacitance parameter measuring device also includes a control module 140, which is connected to the switch, DC power supply 110, and impedance meter LCR in the test circuit 130. The control module 140 controls the DC power supply 110 to charge the energy storage module 120 and controls the switching on and off in the test circuit 130. The voltage stored in the energy storage module 120 is used to apply a high voltage to the semiconductor tube. The control module 140 also receives the test results returned by the impedance meter LCR. Further, as... Figure 2 As shown, the junction capacitance parameter measuring device also includes a switch K10. The DC power supply 110 is connected to the energy storage module 120 through the switch K10. During mass production testing, the switch K10 is in a conducting state, allowing the DC power supply 110 to continuously charge the energy storage module 120. The number of switches K10 can be one or two, connected between the DC power supply 110 and the first and / or second terminals of the energy storage module 120.

[0032] like Figure 2As shown, the test circuit 130 includes a switch K11 and a current limiting component 132 connected in series between the energy storage module 120 and the semiconductor tube. The number of the switch K11 and the current limiting component 132 can also be one or two. When the number of the switch K11 and the current limiting component 132 is one, the switch K11 and the current limiting component 132 can be connected between the first end of the energy storage module 120 and the first end of the semiconductor tube, or connected between the second end of the energy storage module 120 and the second end of the semiconductor tube. When the number of the switch K11 and the current limiting component 132 is two, one of the switch K11 and the current limiting component 132 is connected in series between the first end of the energy storage module 120 and the first end of the semiconductor tube, and the other of the switch K11 and the current limiting component 132 is connected in series between the second end of the energy storage module 120 and the second end of the semiconductor tube. When the switch K11 is turned on, the voltage stored in the energy storage module 120 is transmitted to the semiconductor tube through the current limiting component 132, and a high voltage is applied to the semiconductor tube, so that the impedance tester LCR can measure the junction capacitance parameters.

[0033] Further, the test circuit 130 further includes a bypass conduction component 134 connected in parallel with the current limiting component 132, and the conduction resistance of the bypass conduction component 134 is smaller than the conduction resistance of the current limiting component 132. When the voltage is applied to the semiconductor tube, the bypass conduction component 134 can be first controlled to be turned on for rapid voltage rise, and then the bypass conduction component 134 is turned off and the current limiting component 132 is turned on to continuously apply a high voltage to the semiconductor tube.

[0034] The specific structure of the current limiting component 132 and the bypass conduction component 134 is not unique, and the specific structure of the current limiting component 132 and the bypass conduction component 134 will be described below with reference to the following embodiments. Figure 2 Taking the test circuit 130 including two current limiting components 132 as an example, the current limiting component 132 arranged between the first end of the energy storage module 120 and the first end of the semiconductor tube, and the current limiting component 132 arranged between the second end of the energy storage module 120 and the second end of the semiconductor tube, are both composed of a resistor R2 and a switch K9 in series, i.e., the number of the resistor R2 and the switch K9 is two, and the resistor R2 and the switch K9 are arranged on the line between the first end / second end of the energy storage module 120 and the first end / second end of the semiconductor tube, respectively. The bypass conduction component 134 connected in parallel with the current limiting component 132 between the first end of the energy storage module 120 and the first end of the semiconductor tube is composed of a resistor R1 and a switch K8 in series, and the bypass conduction component 134 connected in parallel with the current limiting component 132 between the second end of the energy storage module 120 and the second end of the semiconductor tube is composed of a switch K8, so that when the switch K8 is turned on, the second end of the energy storage module 120 is directly connected to the second end of the semiconductor tube.

[0035] In addition, the specific structure of the current limiting component 132 and the bypass conduction component 134 will be described below with reference to the following embodiments. Figure 2, the test loop 130 can further include a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a switch K1, a switch K2, a switch K3, a switch K4, a switch K5, a switch K6 and a switch K7, wherein the switch K1, the switch K2, the switch K3 and the switch K5 are all switch pairs, that is, each of them includes a pair of switches. The HCUR port and the HPOT port of the impedance tester LCR are connected to the capacitor C1 and the capacitor C2 respectively, the capacitor C1 is connected to the GF line through the switch K1 and to the DF line through the switch K5, and the capacitor C2 is connected to the GS line through the switch K1 and to the DS line through the switch K5. The LCUR port and the LPOT port of the impedance tester LCR are connected to the capacitor C3 and the capacitor C4 respectively, the capacitor C3 is connected to the GF line through the switch K2 and to the SF line through the switch K3, and the capacitor C4 is connected to the GS line through the switch K2 and to the SS line through the switch K3. The switch K7 and the capacitor C5 are connected in series between the DS line and the SS line, the DS line is connected to the first end of the energy storage module 120 through the corresponding current limiting component 132, the bypass conduction component 134 and the switch K11, and the SS line is connected to the second end of the energy storage module 120 through the corresponding current limiting component 132, the bypass conduction component 134 and the switch K11. The GF line is connected to the SF line through the switch K6, and the SF line is connected to the ground through the switch K4. Among them, the GF line and the GS line are connected to the control end of the semiconductor tube, the DF line and the DS line are connected to the first end of the semiconductor tube, and the SF line and the SS line are connected to the second end of the semiconductor tube.

[0036] The mass production test needs to measure the four parameters Rg, Ciss, Coss and Crss in turn, so the test circuit needs to be switched, and the test loop model is as shown in Figure 2 Taking a MOS tube as an example, the test loop 130 is connected to the MOS tube through six lines GF, GS, DF, DS, SF and SS, which correspond to the gate G, the drain D and the source S of the MOS tube respectively, and the second letters F and S of the six lines represent output and measurement respectively, that is, GF represents the connection with the G terminal of the DUT and is the output terminal, and GS represents the connection with the G terminal of the DUT and is the measurement terminal. Among them, the switch K10 and the switches involved in the test loop 130 are all thermal switches, in order to be suitable for mass production test, all the switches can be realized by relays, and the control ends of the switches are connected to the control module 140 to switch on and off according to the instructions issued by the control module 140. The switches K1 to K7 are used to build test loops of different parameters, and the switches K1, K3 and K7 are closed for Rg&Ciss test, the switches K3, K5, K6 and K7 are closed for Coss test, and the switches K2, K5 and K7 are closed for Crss test.

[0037] Specifically, the control module 140 is used for issuing control commands, displaying measurement results, saving test data, etc. The control module 140 is composed of a PC, a single-chip microcomputer, or other central processing units, and controls the DC power supply 110, the test circuit 130, and the impedance tester LCR through a communication cable to realize the Rg and distributed capacitance parameter test of the semiconductor tube. The power supply performance of the DC power supply 110 does not need to be forcedly required, and specifically, a 2000V 10mA power supply can be used. The energy storage module 120 can use a high-voltage energy storage capacitor, and the capacitance is much larger than the capacitance C5 and the junction capacitance of the measured semiconductor tube, which can meet the use requirement, and the difficulty is much simpler and lower cost than the development difficulty of the high-voltage programmable source. The first charging time calculation formula of the DC power supply 110 for charging the energy storage module 120 is Q = C(100uF) * U(2000V) = I(10mA)T, and the calculated first charging time is 2S. After one-time charging is completed, the use condition can be met.

[0038] The impedance tester LCR can complete impedance measurement in a vector volt-ampere method, an automatic balance bridge method, or the like, and can also directly select an impedance tester already on sale in the market. In order to improve the test precision, the impedance tester LCR completes measurement in a four-wire method: high-end output (HCUR, HC), high-end measurement (HPOT, HP), low-end output (LCUR, LP), and low-end measurement (LPOT, LP).

[0039] In one embodiment, as shown in Figure 2 The junction capacitance parameter measurement device further includes a voltage detection module 150 connected to the energy storage module 120. The voltage detection module 150 monitors the high-voltage charging and discharging during the test process, and is specifically used for detecting the voltage of the energy storage module 120 and / or the voltage applied to the semiconductor tube. The voltage detection module 150 monitors the high-voltage charging and discharging process at the beginning, during, and after the entire test, which further improves the safety of the test. In addition, the control module 140 is also connected with the voltage detection module 150, and the control module 140 performs test protection according to the voltage monitored by the voltage detection module 150.

[0040] In one embodiment, as shown in Figure 3As shown, the voltage detection module 150 includes an equal proportion operational amplifier circuit 152, a reverse operational amplifier circuit 154, a summing circuit 156, and an analog-to-digital converter ADC, the equal proportion operational amplifier circuit 152 is connected to the energy storage module 120 and the summing circuit 156, the reverse operational amplifier circuit 154 is connected to the energy storage module 120 and the summing circuit 156, the summing circuit 156 is connected to the analog-to-digital converter ADC, and the analog-to-digital converter ADC is connected to the control module 140. The voltage across the energy storage module 120 is processed by the equal proportion operational amplifier circuit 152 and the reverse operational amplifier circuit 154, and then transmitted to the summing circuit 156 to obtain a voltage detection signal, and the analog-to-digital converter ADC converts the voltage detection signal into a digital signal and transmits it to the control module 140.

[0041] Specifically, the equal proportion operational amplifier circuit 152 includes an operational amplifier U1, a resistor R11, and a resistor R14, the reverse operational amplifier circuit 154 includes an operational amplifier U2, an operational amplifier U3, a resistor R12, a resistor R13, and a resistor R15, and the summing circuit 156 includes an operational amplifier U4 and a resistor R16. The non-inverting input terminal of the operational amplifier U1 is connected to the first end of the energy storage module 120, the inverting input terminal of the operational amplifier U1 is connected to the output terminal of the operational amplifier U1 through the resistor R11, the output terminal of the operational amplifier U1 is connected to the inverting input terminal of the operational amplifier U4 through the resistor R14, the non-inverting input terminal of the operational amplifier U2 is connected to the second end of the energy storage module 120, the inverting input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2 through the resistor R12, the output terminal of the operational amplifier U2 is connected to the inverting input terminal of the operational amplifier U3, the inverting input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U3 through the resistor R13, the non-inverting input terminal of the operational amplifier U3 is grounded, the output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U4 through the resistor R15, the inverting input terminal of the operational amplifier U4 is connected to the output terminal of the operational amplifier U4 through the resistor R16, the non-inverting input terminal of the operational amplifier U4 is grounded, and the output terminal of the operational amplifier U4 is connected to the analog-to-digital converter ADC, and the analog-to-digital converter ADC is connected to the control module 140.

[0042] The voltage detection module 150 can further include an isolation power supply, and the H+12 port and the H-12 port of the isolation power supply are connected to the positive and negative power supply terminals of each operational amplifier, and the operational amplifier is powered by the isolation power supply. The in-phase input of the operational amplifier can ensure the high resistance of the acquisition end, and will not cause the actual acquisition voltage precision to decrease due to external partial voltage. The first end voltage (upper end voltage) of the energy storage module 120 is output by the equal-ratio operational amplifier circuit 152 in a 1:1 ratio, the second end voltage (lower end voltage) of the energy storage module 120 is followed by the internal operational amplifier of the reverse operational amplifier circuit 154 and is reversed, and then is summed with the upper end voltage in the summing circuit 156, and the actual acquisition voltage = upper end voltage + (-lower end voltage), so as to achieve the purpose of acquiring the voltage between the two ends of the energy storage module 120. The resistor R14 can be a high-voltage-resistant resistor. In order to ensure the precision index during detection, the voltage precision connected to the analog-to-digital converter ADC can be ensured by adjusting the resistor R16 or increasing a plurality of groups of resistors R16, and finally the voltage between the two ends of the energy storage module 120 is converted from an analog quantity to a digital quantity by the analog-to-digital converter ADC.

[0043] In one embodiment, as shown in FIG. 1, Figure 2 The junction capacitance parameter measurement device further includes a discharge module 160 connected to the energy storage module 120, and the discharge module 160 discharges the voltage of the energy storage module 120 when turned on. The discharge module 160 can also be connected to the control module 140 to discharge the voltage according to the instruction of the control module 140.

[0044] As shown in FIG. 1, Figure 4 The discharge module 160 specifically includes a switch tube Q1, a switch tube Q2 and a resistor R17, the control terminals of the switch tube Q1 and the switch tube Q2 are connected to the isolation power supply, and specifically connected to the H+12 port of the isolation power supply, the first end of the switch tube Q1 is connected to the energy storage module 120, the second end of the switch tube Q1 is connected to the first end of the switch tube Q2 and the isolation power supply, and specifically connected to the H port of the isolation power supply, and the second end of the switch tube Q2 is connected to the ground through the resistor R17. The switch tube Q1 and the switch tube Q2 can be controlled switch tubes such as MOS tubes and triodes, and the discharge module 160 can further include an isolation power supply, and the control module 140 is connected to the isolation power supply. Similarly, taking the energy storage capacitor as an example, the MOS tube is driven to be turned on by the control module 140 to form an RC discharge circuit during the discharge process, so as to ensure that the energy storage capacitor will not be damaged due to hot switching during discharge in a high-voltage state.

[0045] It can be understood that the voltage detection module 150 and the discharge module 160 can use independent isolation power supplies respectively, or can share an isolation power supply.

[0046] Specifically, the test scheme for junction capacitance in the industry has been very mature, Ciss=Cgd+Cgs, Coss=Cgd+Cds, Crss=Cgd. Among them, the test circuit of Figures 5 to 7 can complete the rapid measurement of Ciss, Coss and Crss. Based on the improved circuit structure, the junction capacitance test is carried out in the application, and the test efficiency and safety are improved by charging the energy storage capacitor and controlling the closing sequence of switches K1-K11. As Figure 8 shown, taking Ciss test as an example, the specific test process is as follows:

[0047] Step one: close switches K7, K4, K8.

[0048] Among them, K7 is used to build a junction capacitance test standard circuit. In addition, due to the existence of MΩ level resistance R2, the voltage rising speed between the DS of the measured MOS tube is very slow when high voltage is output, reaching seconds. In order to improve the voltage rising speed, switches K4, K8 and bypass resistance R1 are added. The resistance value of resistance R1 is much smaller than that of resistance R2, for example, 10Ω, etc. Before each output voltage change, switches K4 and K8 are first closed to improve the voltage change speed between the DS of the measured MOS tube; after stabilization, switch K8 is disconnected to avoid the influence of the increased bypass on normal test.

[0049] Step two: detect whether the voltage value of the energy storage capacitor is the set value.

[0050] In this application, the DS of the measured MOS tube is no longer directly charged by the DC power supply 110, but the energy storage capacitor is first charged by the DC power supply 110, and after the voltage across the energy storage capacitor reaches the set value, the energy storage capacitor is used to quickly charge the test circuit 130. Therefore, whether the energy storage capacitor voltage can reach the set voltage is particularly important for the accuracy of the measurement result and the safety of the measurement device. When performing mass production test, switch K10 will not be disconnected again except for the first time charging, and the energy storage capacitor is always charged. The voltage of the energy storage capacitor is monitored during the test process by the voltage detection module 150, and the control module 140 determines the current state of the measurement device according to the detected voltage value, and controls the on-off of the test circuit to perform rapid test and safety guarantee.

[0051] The control module 140 closes the switch K10 to connect the loop between the DC power supply 110 and the energy storage capacitor, and charges the energy storage capacitor for the first time or recharges it. During the charging process, the voltage of the energy storage capacitor is continuously monitored by the voltage detection module 150. If the voltage across the energy storage capacitor is close to 0V, it is determined that there is an abnormality between the DC power supply 110 and the energy storage capacitor. If the energy storage capacitor has a voltage but does not reach the set value, it can be determined that there is an abnormality in the charging loop. Only when the voltage of the energy storage capacitor reaches the set value, it is considered that the energy storage capacitor is fully charged and the next step can be performed. When the detected voltage value is the set value, it is considered that the current measurement device is in normal production test, and no operation is performed, waiting for the next step.

[0052] Step three: close the switch K11.

[0053] After the energy storage capacitor is fully charged, the measurement device has a pressurization condition, and after closing the switch K11, the energy storage capacitor can be used to pressurize the D and S ends of the measured MOS tube. According to the time constant formula τ = R*C, since the resistance R1 is small, the charging speed of the test loop for the shorted capacitor can be greatly improved, so the voltage at the D and S ends of the measured MOS tube will quickly reach the set DC bias voltage value.

[0054] Step four: detect whether VDS reaches the set voltage.

[0055] For safety reasons, when closing the switch K11 to charge the D and S ends of the measured MOS tube, the voltage at the D and S ends of the measured MOS tube is also monitored during the test process by the voltage detection module 150. According to the detected voltage value, the current state of the measurement device is determined. When the voltage reaches the set value, it is considered that the test loop is normal and the pressurization of the measured MOS tube is complete. When the voltage does not reach the set value, it is considered that the test loop is abnormal, and the power output should be immediately disconnected and the test loop should be disconnected to prevent damage to the measurement device caused by abnormally high voltage.

[0056] Step five: close the switches K9, K1, K3; open the switches K4, K8.

[0057] Since the impedance tester LCR, whether purchased as a finished product or self-developed, is very expensive, and the test interface of the impedance tester LCR generally cannot withstand high voltage impact, it is necessary to protect the test port of the impedance tester LCR from high voltage. After the voltage is stabilized, the DC blocking capacitor C1-C4 can play a role in isolating DC to protect the impedance tester LCR from damage, but during the charging process, the large-capacity DC blocking capacitor loses its function. Therefore, this step has two main purposes. The first purpose is to close the switches K1, K3 to connect the impedance tester LCR, and the second purpose is to disconnect the charging resistor R1 and connect the current limiting resistor R2 to provide charging protection.

[0058] In addition, the application is also protected by timing control. The switches K1 and K3 are disconnected during the charging process, and then the switches K1 and K3 are connected after the charging is completed, so as to realize the impedance tester LCR high-voltage protection in time sequence.

[0059] Due to the efficiency requirement in mass production, a small resistance R1 is used in the charging circuit during the charging process, so as to improve the charging speed of the circuit. However, after the voltage boosting is completed, since the charging power is inversely proportional to the resistance value of the circuit, the smaller the resistance value is, the greater the power generated by the circuit is. In order to prevent the components in the test circuit from being damaged by high voltage in a long time of mass production test, the switch K9 is closed, the switches K4 and K8 are disconnected, and the test circuit is switched to the resistance R2 for current limiting after the voltage boosting is completed. The resistance value of the resistance R2 can be 1MΩ.

[0060] Step six: LCR measurement.

[0061] In this step, the complete test circuit is built and the process of direct current bias voltage boosting is completed. Next, the parameters of the junction capacitance are measured by the impedance tester LCR. The impedance tester LCR uses the automatic balance bridge method to complete the measurement. Essentially, the final test result is obtained by measuring the amplitude and phase difference of the voltage before and after the measured MOS tube, and then fitting the model.

[0062] Step seven: disconnect the switches K1 and K3; close the switches K4 and K8; disconnect the switch K9.

[0063] This step is the opposite of step five, which is mainly used to disconnect the impedance tester LCR and switch back to the charging circuit, so as to prepare for discharging the voltage between the D and S terminals of the measured MOS tube.

[0064] Step eight: disconnect the VDS voltage input.

[0065] There are two ways to disconnect the VDS voltage input according to whether it is mass production test. One is single test mode, which only boosts once, disconnects the switch K10 after the measurement is completed, and does not charge the energy storage capacitor. The test is directly ended after the subsequent energy storage capacitor is discharged. The other is mass production test mode. In the mass production test mode, the energy storage capacitor is not charged and discharged frequently. The switch K10 is always closed to charge the energy storage capacitor. The VDS voltage input between the D and S terminals of the measured MOS tube is disconnected by disconnecting the switch K11.

[0066] Step nine: detect whether the VDS voltage is discharged to 0.

[0067] The voltage detection module 150 is also used to monitor the voltage VDS of the MOS tube during the loop discharge voltage process. If the loop does not discharge the voltage to 0 within a specified time, the control module 140 can determine that the loop may have an abnormality. When the voltage VDS is detected as 0V, it is considered that there is no voltage in the test loop, and the relay switching operation can be performed to prevent damage to the relay from heat cutting.

[0068] In addition, during the monitoring of the pressurization and discharge, once the voltage is abnormal, the control module 140 will stop the voltage output by opening the switch K10, and at the same time, all relays will be opened to protect the components of the measurement system.

[0069] Step ten: open switches K1, K3, K4, K7, K8, K9, and K11.

[0070] After a round of testing, all relays except switch K10 are opened, and the measurement device is restored to the initialization state, waiting for the next test.

[0071] The above junction capacitance parameter measurement device increases the energy storage module 120 to ensure that the gate resistance and junction capacitance are quickly tested and randomly switched under high voltage bias. After charging the energy storage module 120 to the set value for the first time, the high voltage is isolated from the loop part by the hot cutting switch, and there is no need to use a high-performance power supply for power supply, which realizes low-cost junction capacitance parameter measurement and reduces the measurement cost.

[0072] The technical features of the above-described embodiments can be combined in any way. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present application.

[0073] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the utility model patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, some modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A junction capacitance parameter measuring device, characterized by, The device comprises a direct current power supply, an energy storage module, a test circuit and an impedance tester; the direct current power supply is connected to the energy storage module, the test circuit is connected to the energy storage module, the impedance tester and a semiconductor tube to be tested; the direct current power supply is used to charge the energy storage module, the test circuit applies voltage to the semiconductor tube according to the voltage of the energy storage module after charging, so that the impedance tester measures the junction capacitance parameters of the semiconductor tube through the test circuit.

2. The apparatus of claim 1, wherein, The test circuit comprises a switch K11, a current limiting component and a bypass conduction component; the switch K11 and the current limiting component are connected in series between the energy storage module and the semiconductor tube; the bypass conduction component is connected in parallel with the current limiting component; and the conduction resistance of the bypass conduction component is smaller than the conduction resistance of the current limiting component.

3. The apparatus of claim 2, wherein, The test circuit further comprises a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a switch K1, a switch K2, a switch K3, a switch K4, a switch K5, a switch K6 and a switch K7; the HCUR port and the HPOT port of the impedance tester are connected to the capacitor C1 and the capacitor C2 respectively; the capacitor C1 is connected to the GF line through the switch K1 and to the DF line through the switch K5; the capacitor C2 is connected to the GS line through the switch K1 and to the DS line through the switch K5; the LCUR port and the LPOT port of the impedance tester are connected to the capacitor C3 and the capacitor C4 respectively; the capacitor C3 is connected to the GF line through the switch K2 and to the SF line through the switch K3; the capacitor C4 is connected to the GS line through the switch K2 and to the SS line through the switch K3; the switch K7 and the capacitor C5 are connected in series between the DS line and the SS line; the DS line is connected to the first end of the energy storage module through the corresponding current limiting component, bypass conduction component and switch K11; the SS line is connected to the second end of the energy storage module through the corresponding current limiting component, bypass conduction component and switch K11; the GF line is connected to the SF line through the switch K6; and the SF line is connected to the ground through the switch K4; wherein the GF line and the GS line are connected to the control end of the semiconductor tube; the DF line and the DS line are connected to the first end of the semiconductor tube; and the SF line and the SS line are connected to the second end of the semiconductor tube.

4. The apparatus of claim 1, wherein, The direct current power supply is connected to the energy storage module through a switch K10; and the switch K10 is in the conduction state during the mass production test, so that the direct current power supply continuously charges the energy storage module.

5. The apparatus of any one of claims 1-4, wherein, A voltage detection module is further connected to the energy storage module; the voltage detection module is used to detect the voltage of the energy storage module and / or the voltage applied to the semiconductor tube.

6. The apparatus of claim 5, wherein, A control module is further connected to the switches in the test circuit, the voltage detection module, the direct current power supply and the impedance tester.

7. The apparatus of claim 6, wherein, The voltage detection module comprises an equal proportion operational amplifier circuit, a reverse operational amplifier circuit, a summing circuit and an analog-to-digital converter, the equal proportion operational amplifier circuit is connected with the energy storage module and the summing circuit, the reverse operational amplifier circuit is connected with the energy storage module and the summing circuit, the summing circuit is connected with the analog-to-digital converter, and the analog-to-digital converter is connected with the control module.

8. The apparatus of claim 7, wherein, The equal proportion operational amplifier circuit comprises an operational amplifier U1, a resistor R11 and a resistor R14, the reverse operational amplifier circuit comprises an operational amplifier U2, an operational amplifier U3, a resistor R12, a resistor R13 and a resistor R15, and the summing circuit comprises an operational amplifier U4 and a resistor R16. The non-inverting input terminal of the operational amplifier U1 is connected with the first end of the energy storage module, the inverting input terminal of the operational amplifier U1 is connected with the output terminal of the operational amplifier U1 through the resistor R11, the output terminal of the operational amplifier U1 is connected with the inverting input terminal of the operational amplifier U4 through the resistor R14, the non-inverting input terminal of the operational amplifier U2 is connected with the second end of the energy storage module, the inverting input terminal of the operational amplifier U2 is connected with the output terminal of the operational amplifier U2 through the resistor R12, the output terminal of the operational amplifier U2 is connected with the inverting input terminal of the operational amplifier U3, the inverting input terminal of the operational amplifier U3 is connected with the output terminal of the operational amplifier U3 through the resistor R13, the non-inverting input terminal of the operational amplifier U3 is grounded, the output terminal of the operational amplifier U3 is connected with the inverting input terminal of the operational amplifier U4 through the resistor R15, the inverting input terminal of the operational amplifier U4 is connected with the output terminal of the operational amplifier U4 through the resistor R16, the non-inverting input terminal of the operational amplifier U4 is grounded, and the output terminal of the operational amplifier U4 is connected with the analog-to-digital converter.

9. The apparatus of any one of claims 1-4, wherein, The voltage detection module further comprises a discharge module, the discharge module is connected with the energy storage module, and the discharge module discharges the voltage of the energy storage module when turned on.

10. The apparatus of claim 9, wherein, The discharge module comprises a switch tube Q1, a switch tube Q2 and a resistor R17, the control end of the switch tube Q1 and the control end of the switch tube Q2 are connected with an isolation power supply, the first end of the switch tube Q1 is connected with the energy storage module, the second end of the switch tube Q1 is connected with the first end of the switch tube Q2, and the second end of the switch tube Q2 is grounded through the resistor R17.

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